Dissertations / Theses: 'Slot allocation'

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Schmid, Thomas 1969. "Slot allocation at European airports." Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=30326.

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International air transport has grown at a staggering rate over the last 50 years and the industry which supports it, now bears little resemblance to that which existed even twenty-five years ago. As the number of operators and the size of their respective fleets have increased, so too have the pressures on the infrastructure which support them. Particularly affected are the major airports where runway, apron and terminal capacity are limited. Unlike other elements of the aviation infrastructure, airport capacity is physically constrained and therefore capacity increases can only be obtained through further development or through more efficient uses of existing resources. As the first option is politically controversial and the latter only provides for incremental increases, the air transport industry, through IATA, has developed an allocation mechanism to distribute available capacity based on historic precedence. This thesis reviews the main issues surrounding the current regime. (Abstract shortened by UMI.)

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Schmid, Thomas. "Slot allocation at European airports." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ64302.pdf.

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Milner, Joseph M. (Joseph Micah). "Dynamic slot allocation with airline participation." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11882.

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Moessner, Philipp. "Slot allocation in the United States and Europe." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99146.

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The following thesis describes and analyzes the development of the U.S. slot allocation system from 1968 until today, in order to draw relevant conclusions for a new European Slot Regulation. The European Commission is currently drafting a new Slot Regulation purporting to introduce market mechanisms. A similar approach was espoused in the United States from 1986 onward, but was ultimately supplanted by overriding legislation in 2000. The analysis of the U.S. slot allocation system reveals the reasons underlying its abolition and queries whether this experience can be successfully transposed in Europe. The thesis commences by providing general information on the definition of slots, slot allocation, and airport capacity. A brief review of the European Commission's current consultation process on the implementation of market mechanisms for slot allocation follows. The main part of the thesis discusses the U.S. High Density Rule and the Rules for the Allocation and Transfer of High Density Airport Slots in historical order. Some criticisms frequently voiced assert that the Rules artificially limited access to airports, constituted barriers to market entry, restricted airline competition, generated higher fares, and yielded adverse effects on smaller communities which, in turn, lost access to key markets. Through a favorable assessment of the Rules, the thesis analyses these concerns and concludes that the suppression of the Rules was rather prompted by local political motivations than by other rationalities. However, experiences drawn from the U.S. Rules demonstrate that a future European secondary market for slots, if implemented under a grand fathering system, will likely have a positive impact on the efficiency of airport capacity, but not on access to the market and competition.

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Stevens, David Story. "TDMA slot allocation strategies for mobile packet radio networks." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/9190.

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Khan, Eraj, and Khizar Hayat. "GPS based Vehicle Conflict Measurement and Dynamic Slot Allocation." Thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-654.

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7

Park, JinSoo. "Adaptive Asymmetric Slot Allocation for Heterogeneous Traffic in WCDMA/TDD Systems." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/29630.

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Even if 3rd and 4th generation wireless systems aim to achieve multimedia services at high speed, it is rather difficult to have full-fledged multimedia services due to insufficient capacity of the systems. There are many technical challenges placed on us in order to realize the real multimedia services. One of those challenges is how efficiently to allocate resources to traffic as the wireless systems evolve. The review of the literature shows that strategic manipulation of traffic can lead to an efficient use of resources in both wire-line and wireless networks. This aspect brings our attention to the role of link layer protocols, which is to orchestrate the transmission of packets in an efficient way using given resources. Therefore, the Media Access Control (MAC) layer plays a very important role in this context. In this research, we investigate technical challenges involving resource control and management in the design of MAC protocols based on the characteristics of traffic, and provide some strategies to solve those challenges. The first and foremost matter in wireless MAC protocol research is to choose the type of multiple access schemes. Each scheme has advantages and disadvantages. We choose Wireless Code Division Multiple Access/Time Division Duplexing (WCDMA/TDD) systems since they are known to be efficient for bursty traffic. Most existing MAC protocols developed for WCDMA/TDD systems are interested in the performance of a unidirectional link, in particular in the uplink, assuming that the number of slots for each link is fixed a priori. That ignores the dynamic aspect of TDD systems. We believe that adaptive dynamic slot allocation can bring further benefits in terms of efficient resource management. Meanwhile, this adaptive slot allocation issue has been dealt with from a completely different angle. Related research works are focused on the adaptive slot allocation to minimize inter-cell interference under multi-cell environments. We believe that these two issues need to be handled together in order to enhance the performance of MAC protocols, and thus embark upon a study on the adaptive dynamic slot allocation for the MAC protocol. This research starts from the examination of key factors that affect the adaptive allocation strategy. Through the review of the literature, we conclude that traffic characterization can be an essential component for this research to achieve efficient resource control and management. So we identify appropriate traffic characteristics and metrics. The volume and burstiness of traffic are chosen as the characteristics for our adaptive dynamic slot allocation. Based on this examination, we propose four major adaptive dynamic slot allocation strategies: (i) a strategy based on the estimation of burstiness of traffic, (ii) a strategy based on the estimation of volume and burstiness of traffic, (iii) a strategy based on the parameter estimation of a distribution of traffic, and (iv) a strategy based on the exploitation of physical layer information. The first method estimates the burstiness in both links and assigns the number of slots for each link according to a ratio of these two estimates. The second method estimates the burstiness and volume of traffic in both links and assigns the number of slots for each link according to a ratio of weighted volumes in each link, where the weights are driven by the estimated burstiness in each link. For the estimation of burstiness, we propose a new burstiness measure that is based on a ratio between peak and median volume of traffic. This burstiness measure requires the determination of an observation window, with which the median and the peak are measured. We propose a dynamic method for the selection of the observation window, making use of statistical characteristics of traffic: Autocorrelation Function (ACF) and Partial ACF (PACF). For the third method, we develop several estimators to estimate the parameters of a traffic distribution and suggest two new slot allocation methods based on the estimated parameters. The last method exploits physical layer information as another way of allocating slot to enhance the performance of the system. The performance of our proposed strategies is evaluated in various scenarios. Major simulations are categorized as: simulation on data traffic, simulation on combined voice and data traffic, simulation on real trace data. The performance of each strategy is evaluated in terms of throughput and packet drop ratio. In addition, we consider the frequency of slot changes to assess the performance in terms of control overhead. We expect that this research work will add to the state of the knowledge in the field of link-layer protocol research for WCDMA/TDD systems.
Ph. D.

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8

Jenkins, Alexander. "Relational Training Of Contextual Cues And Responses Allocation Towards Slot Machines." OpenSIUC, 2020. https://opensiuc.lib.siu.edu/theses/2778.

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Slot machine gambling is the most addictive form of gambling and it is the most popular type of gambling in America (Abbot, 2001). The United States ranks number 1 in annual gambling losses, which equaled to about 40 million dollars (Ghezzi, Lyons, & Dixon, 2000). The present study sought to expand on previous studies by Zlomske & Dixon (2006) and Hoon et al. (2008) by using of contextual cues to teach conditional discrimination relations, one through exclusion, and evaluated the participants' response allocation across four different colored slot machines. Results demonstrated that all of the participants except for one was able to score one correct response when tested on the exclusionary stimuli. Further analysis showed that only a few of the participants' response allocation on the gambling task was altered towards the slot machines that shared the contextual cues of "best" and "greater than".

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Månsson, Jonas. "Principles for Channel Allocation in GSM." Thesis, Linköping University, Department of Electrical Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-10697.

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In today's GSM system there is a complex resource situation when it comes to the scarce TDMA channels in the air interface, the time slots. There are both voice call services that use one or a half time slot and there are packet data users, that may share time slots with other packet data users, and they can use multiple channels at the same time. Allocating time to users is a crucial part in the system and it may affect the performance for the end user substantially.

In the future there may be more types of services than just voice and packet data and that these services may have specific demands on their channels, time slots. That means they would not be able to use just any of the available channels. The way to "give" services channels is what is called channel allocation. In this thesis four different services and three different principles for channel allocation is implemented in a Matlab simulator and simulated. The thesis goal is to determine which principle is best for which mix of services.

The principles that have been investigated are Flexible Algorithm that lets all services use all channels, Fix Dedication Algorithm where all channels are dedicated to a service and only can be used by that one and finally Soft Dedication Algorithm where all channels are dedicated to a service but may be used by other services when it is not needed by the preferred one.

The conclusion is, simplified, that the Soft Dedication Algorithm generates low blocking rates, high bandwidth and that it is a quite robust principle although the borrowing user may be preempted. It may not always be the best one but over all it is the one to prefer.

Detta examensarbete är utfört på uppdrag av och i samarbete med Ericsson och rör kanal- och resurshantering i GSM-systemet.

Ett ständigt problem vid trådlös och mobil kommunikation är den begränsade mängd frekvenser som finns tillgängliga i radiogränssnittet och hur pass nära två radioresursers frekvenser kan ligga varandra. I GSM används TDMA (Time Division Multiple Access) för att få plats med många användare på ett smalt frekvensband. TDMA innebär förenklat att tiden delas upp i åtta tidsluckor och att varje användare får tillgång till en av radioresurserna under en sådan tidslucka (kanal). Detta gäller både i upp- och nedlänk.

I nuläget finns två tjänster, paketdata och tal, som använder tidsluckorna på olika sätt. En talanvändare använder en eller en halv lucka själv medan paketdataanvändare kan dela på en eller flera luckor. Det finns alltså en mängd olika sätt att allokera, "dela ut", dessa luckor till ett givet antal användare. I nuläget har man en väl fungerande algoritm för detta men man tror att det i framtiden kommer att finnas fler tjänster med mer specifika krav på sina tidsluckor (kanaler) och att man då inte längre kan använda samma princip för kanalallokeringen.

I detta exjobb har tre nya, enkla och renodlade principer för kanalallokering undersökts för fyra fiktiva tjänster. Det tre principerna är Flexible Algorithm, där alla tjänster tillåts använda alla kanaler, Fix Dedication Algorithm, där alla kanaler är dedicerade till någon tjänst och endast kan användas av just denna tjänst; och slutligen Soft Dedication Algorithm som fungerar liknande den föregående men här kan tjänster "låna" kanaler av andra tjänster så längs som de är lediga. I Soft Dedication Algorithm kan en eventuell "låntagare" bli avbruten om en användare av rätt tjänst inte hittar en ledig kanal.

Utvärdering har skett genom att simulera systemet i en, delvis egengjord, Matlabsimulator.

Resultaten visar, förenklat, att Soft Dedication Algorithm är den bästa vad gäller låg blockering, kanalutnyttjande och även bandbredder. Den är även förhållandevis robust mot variationer i last.

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Milic, Dejan. "EXAMINING THE EFFECTS OF CONTEXTUAL STIMULI ON RESPONSE ALLOCATION IN SLOT MACHINE GAMBLING." OpenSIUC, 2020. https://opensiuc.lib.siu.edu/theses/2772.

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The present study sought to identify the effects that derived relational training had on simulated gambling behavior with slot machines. Prior to conducting any relational training procedures, participants' relational responses in each contextual condition was probed. Each of the four backgrounds/conditions (red, blue, green, yellow) were presented with various stimuli from differing stimulus classes. Twenty trials were presented with no feedback for correct responding. Upon completion of the probes, pretest preference assessments were administered with blue and red slot machines being concurrently available for twenty trials then green and yellow slot machines doing the same. Following the pretest preference assessment, relational training began, here stimuli from each of the stimulus classes were presented on screen for three of the contextual conditions with the blue contextual condition left out to assess for possible derived relational responses. After completion, the second set of relational probes and posttest preference assessments began to assess if relational training altered the response allocation of slot machines and accuracy of responding during probes. After relational training, all participants showed an increase in response allocation to the red slot machine and a decrease to the blue. The yellow slot machine was selected increasingly with three participants while green was selected more often with one individual, one staying at the same number, and two selecting it less than in the pretest.

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11

Muckey, Linda M. "Response Allocation as Preference: Examining the Effect of Bonus Features in Slot Machines." OpenSIUC, 2017. https://opensiuc.lib.siu.edu/theses/2168.

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Nearly 2% of the population meets the diagnostic criteria for gambling disorders (American Psychiatric Association, 2013). The convergence of gambling and digital media has introduced new features to slot machines such as bonuses. Little research exists on the inclusion of bonuses in slot machine play, but early evidence suggests that these features may alter response allocation (Belisle, Owens, Dixon, Malkin, & Jordan, 2017). The current investigation examined two different types of bonuses currently available in slot machines: free spins and choice based bonuses. Using response allocation as the dependent variable, the effects of two types across dense and lean schedules were examined. Results of the two-way repeated measures ANOVA suggest a statistically significant effect of type of bonus, F (1,32) =6.031, p = .026, as well as win density, F (1,32) =8.598, p = .010. Limitations and avenues for further research are discussed.

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Iozzi, Alberto. "Essays on regulation : theory and practice." Thesis, University of York, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313959.

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Benlic, Una. "Heuristic search for allocation of slots at network level." Elsevier, 2017. https://publish.fid-move.qucosa.de/id/qucosa%3A72805.

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This paper considers the allocation of slots for a network of coordinated (congested) airports, where the term “slot” refers to a time on a specific day when a carrier is given permission to use the full range of airport infrastructure for the purpose of landing and take-off at a slot-controlled airport. We take into account the existing IATA rules and guidelines: priorities of requests for slots, the capacity limitations at each airport, the minimal turnaround time between arrival and subsequent departure of the same aircraft, and allocation to series of slots rather than to individual slots. Given the complexity of the problem, we propose an approach that consists of (i) a constructive heuristic procedure to generate a feasible and coherent allocation of slots for each airport from the network, and (ii) an iterative heuristic to improve the quality of an initial feasible solution in terms of the schedule delay (time difference between allocated time slots and airline requests). To evaluate whether the approach would be practical in real operation, we perform tests on a set of generated benchmark instances that span an entire scheduling season. The instances differ by the number of airports in the network and by the distribution of requests among airports from a given network - the largest number of airports forming a network is 100, while the maximum total number of aircraft movements considered on a half-yearly basis exceeds . We provide computational comparisons with solutions obtained when each airport from a network is considered independently (the en-route constraint is ignored). These results reveal that the consideration of the en-route constraint, which ensures a coherent allocation of slots at origin and destination airports, introduces only a minor degradation in the schedule delay and in the number of unaccommodated requests. Furthermore, we investigate the heuristic performance for reduced-capacity scenarios.

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Pöschl, Felix. "The Potential Effects of Market-based Slot Allocation Schemes on Airline Networks in the European Union." Institut für Transportwirtschaft und Logistik, WU Vienna University of Economics and Business, 2006. http://epub.wu.ac.at/410/1/document.pdf.

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Kwon, Bongkyoung Kwon. "Adaptive frame structure and OFDMA resource allocation in mobile multi-hop relay networks." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31818.

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Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010.
Committee Chair: Dr. John A. Copeland; Committee Member: Dr. George F. Riley; Committee Member: Dr. Henry L. Owen; Committee Member: Dr. Mary Ann Ingram; Committee Member: Dr. Patrick Traynor. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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Schönemann, René [Verfasser], Jürgen [Akademischer Betreuer] Siegmann, Jürgen [Gutachter] Siegmann, and Thomas [Gutachter] Siefer. "Scheduling rail freight node operations through a slot allocation approach / René Schönemann ; Gutachter: Jürgen Siegmann, Thomas Siefer ; Betreuer: Jürgen Siegmann." Berlin : Technische Universität Berlin, 2016. http://d-nb.info/1156181763/34.

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Hafner, Florian. "IMPROVING AIRLINE SCHEDULE RELIABILITY USING A STRATEGIC MULTI-OBJECTIVE RUNWAY SLOT ASSIGNMENT SEARCH HEURISTIC." Doctoral diss., University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3259.

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Improving the predictability of airline schedules in the National Airspace System (NAS) has been a constant endeavor, particularly as system delays grow with ever-increasing demand. Airline schedules need to be resistant to perturbations in the system including Ground Delay Programs (GDPs) and inclement weather. The strategic search heuristic proposed in this dissertation significantly improves airline schedule reliability by assigning airport departure and arrival slots to each flight in the schedule across a network of airports. This is performed using a multi-objective optimization approach that is primarily based on historical flight and taxi times but also includes certain airline, airport, and FAA priorities. The intent of this algorithm is to produce a more reliable, robust schedule that operates in today's environment as well as tomorrow's 4-Dimensional Trajectory Controlled system as described the FAA's Next Generation ATM system (NextGen). This novel airline schedule optimization approach is implemented using a multi-objective evolutionary algorithm which is capable of incorporating limited airport capacities. The core of the fitness function is an extensive database of historic operating times for flight and ground operations collected over a two year period based on ASDI and BTS data. Empirical distributions based on this data reflect the probability that flights encounter various flight and taxi times. The fitness function also adds the ability to define priorities for certain flights based on aircraft size, flight time, and airline usage. The algorithm is applied to airline schedules for two primary US airports: Chicago O'Hare and Atlanta Hartsfield-Jackson. The effects of this multi-objective schedule optimization are evaluated in a variety of scenarios including periods of high, medium, and low demand. The schedules generated by the optimization algorithm were evaluated using a simple queuing simulation model implemented in AnyLogic. The scenarios were simulated in AnyLogic using two basic setups: (1) using modes of flight and taxi times that reflect highly predictable 4-Dimensional Trajectory Control operations and (2) using full distributions of flight and taxi times reflecting current day operations. The simulation analysis showed significant improvements in reliability as measured by the mean square difference (MSD) of filed versus simulated flight arrival and departure times. Arrivals showed the most consistent improvements of up to 80% in on-time performance (OTP). Departures showed reduced overall improvements, particularly when the optimization was performed without the consideration of airport capacity. The 4-Dimensional Trajectory Control environment more than doubled the on-time performance of departures over the current day, more chaotic scenarios. This research shows that airline schedule reliability can be significantly improved over a network of airports using historical flight and taxi time data. It also provides for a mechanism to prioritize flights based on various airline, airport, and ATC goals. The algorithm is shown to work in today's environment as well as tomorrow's NextGen 4-Dimensional Trajectory Control setup.
Ph.D.
Department of Industrial Engineering and Management Systems
Engineering and Computer Science
Industrial Engineering PhD

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Kim, Sang Hyun. "Airport control through intelligent gate assignment." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50277.

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This dissertation aims at improving the efficiency, robustness, and flexibility of airport operations through intelligent gate assignment. Traditional research on gate assignment focuses on the accommodation of passengers' demands such as walking time of passengers, and the robustness of gate assignment. In spite of its importance on the ramp operations, there is a lack of research to account ramp congestion when gates are assigned. Therefore, this dissertation proposes a new perspective on the gate assignment that accounts for ramp congestion. For that purpose, a ramp operations model based on observations at Atlanta airport is presented to understand the characteristics of aircraft movement on the ramp. The proposed gate assignment problem minimizes passenger-time spent on ramp areas. In addition, this dissertation is conducted to satisfy the needs of passengers, aircraft, and operations from the perspectives of passengers. Using actual passenger data at a major hub airport, the proposed gate assignment is assessed by means of passengers' transit time, passengers' time spent on the ramp, and passengers' waiting time for a gate. Results show that the proposed gate assignment outperforms the current gate assignment in every metric. This dissertation also analyzes the impact of gate assignment on departure metering, which controls the number of pushbacks in order to reduce airport congestion. Then, some of departing flights are held at gates, so it increases the chance of gate conflict, which reduces the efficiency of departure metering as well as ramp operations. In order to analyze the impact of gate assignment on departure metering, this dissertation simulates departure processes at two airports. Results show that the proposed robust gate assignment reduces the occurrence of gate conflicts under departure metering and helps to utilize gate-holding times to some extent.

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Soua, Ridha. "Wireless sensor networks in industrial environment : energy efficiency, delay and scalability." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2014. http://tel.archives-ouvertes.fr/tel-00978887.

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Some industrial applications require deterministic and bounded gathering delays. We focus on the joint time slots and channel assignment that minimizes the time of data collection and provides conflict-free schedules. This assignment allows nodes to sleep in any slot where they are not involved in transmissions. Hence, these schedules save the energy budjet of sensors. We calculate the minimum number of time slots needed to complete raw data convergecast for a sink equipped with multiple radio interfaces and heterogeneous nodes traffic. We also give optimal schedules that achieve the optimal bounds. We then propose MODESA, a centralized joint slots and channels assignment algorithm. We prove the optimality of MODESA in specific topologies. Through simulations, we show that MODESA is better than TMCP, a centralized subtree based scheduling algorithm. We improve MODESA with different strategies for channels allocation. In addition, we show that the use of a multi-path routing reduces the time of data collection .Nevertheless, the joint time slot and channels assignment must be able to adapt to changing traffic demands of the nodes ( alarms, additional requests for temporary traffic ) . We propose AMSA , an adaptive joint time slots and channel assignment based on incremental technical solution. To address the issue of scalability, we propose, WAVE, a distributed scheduling algorithm for convergecat that operates in centralized or distributed mode. We show the equivalence of schedules provided by the two modes.

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Veverka, Jakub. "Vývojové trendy letecké dopravy mezi člůenskými státy EU a severoamerickým kontinentem." Master's thesis, Vysoká škola ekonomická v Praze, 2009. http://www.nusl.cz/ntk/nusl-4885.

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The final thesis analyzes the actual situation of air transport in North America and the EU. New Open skies treaty signed by EU and USA (also EU and Canada) is the objective of the final thesis. An other goal is its influence on transatlantic flights. Moreover the final thesis treats of the allocation of the airport's slots and the actual safety situation as well. Finally there is a small part about alternative jet fuels and the perspectives of air freight transport.

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Fredriksson, Daniel, and Anders Schweitz. "Technical Verification and Validation of TIS-B using VDL Mode 4." Thesis, Linköping University, Department of Science and Technology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2393.

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This report is a technical verification and validation of Traffic Information Service Broadcast (TIS-B) using the data link VDL Mode 4.

The main objective of the report is to examine the usefulness of TIS-B considering the results from tests performed in the Stockholm Terminal Area and for the Advanced Surface Movement Guidance and Control System (A-SMGCS) at Arlanda airport. The results are compared with the requirements that have been set by the standardisation organisations ICAO, RTCA, Eurocontrol and Eurocae. TIS-B is however such a new concept, so most of the operational requirements have not yet been defined.

The process for performing the evaluation of TIS-B involves three stages:

· Study the requirements on TIS-B, ADS-B, radar and A-SMGCS.

· Verify TIS-B by performing tests at Arlanda airport.

· Validate the test results through analysis.

A theoretical study of slot allocation optimisation is performed to decide how the slot allocation is to be implemented.

The report includes a Functional Hazard Analysis (FHA). The FHA is done to see if the applications for TIS-B are ready for implementation or if more hazard preventing actions has to be taken, before any operational actions can be performed.

The report also involves a theoretical introduction to Air Traffic Management (ATM), Surveillance techniques and TIS-B.

All parts included in the report results in conclusions and recommendations regarding the TIS-B service.

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Cholankeril, Eric J. (Eric John) 1981. "Evaluation of an auction mechanism for allocating airport arrival slots." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/87394.

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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.
Includes bibliographical references (p. 89-91).
by Eric J. Cholankeril.
M.Eng.

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Zidi, Chaima. "Energy efficient underwater acoustic sensor networks." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCB003/document.

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Les réseaux de capteurs acoustiques sous-marins (UW-ASN) sont les plus nouveaux achèvements technologiques en termes de communication. Les UW-ASN visent à observer et à explorer les lacs, les rivières, les mers et les océans. Récemment, ils ont été soumis à une attention particulière en raison de leur grand potentiel en termes d'applications prometteuses dans divers domaines (militaires, environnementaux, scientifiques ...) et aux nouvelles questions scientifiques qu'ils suscitent. Un problème majeur dans les UW-ASN est l'épuisement rapide de l'énergie, car une grande puissance est nécessaire pour la communication acoustique, tandis que le budget de la batterie des capteurs est limité. Par conséquent, les protocoles de communication énergétiques revêtent une importance primordiale pour faire usage judiciaire du budget énergétique disponible. Dans ce contexte, cette thèse vise à étudier les principales caractéristiques des capteurs acoustiques sous-marins difficiles afin de concevoir des protocoles de communication énergétiques, plus spécifiquement au niveau routage et MAC. Tout d'abord, nous abordons le problème des trous énergétiques dans UW-ASN. Le problème du « sink-hole » se produit lorsque les capteurs les plus proches du sink épuisent leur énergie plus rapidement en raison de leur charge plus lourde. En effet, ces capteurs, en particulier ceux qui sont à un seul saut du sinkstatique, agissent comme des relais pour tous les autres capteurs, ce qui leur épuise sévèrement l’énergie.A la couche de routage,en particulier, nous proposons de distribuer la charge transmise par chaque capteur parmi plusieurs voisins potentiels, en supposant que les capteurs peuvent ajuster leur gamme de communication entre deux niveaux lorsqu'ils envoient ou transmettent des données. Plus précisément, nous déterminons pour chaque capteur l'ensemble des prochains sauts avec les poids de charge associés qui entraînent un épuisement équitable d'énergie entre tous les capteurs du réseau. Ensuite, nous étendons notre stratégie de routage équilibrée en supposant que chaque capteur n'est pas seulement capable d'ajuster sa puissance d'émission à 2 niveaux mais aussi jusqu'à n niveaux où n> 2. Par conséquent, à la couche de routage, pour chaque valeur possible de n, nous déterminons pour chaque capteur l'ensemble des éventuels sauts avec les poids de charge associés qui mènent à une consommation d'énergie équitable chez tous les capteurs du réseau. En outre, nous obtenons le nombre optimal de puissances de transmission n qui équilibre la consommation d'énergie de tous les capteurs pour chaque configuration de réseau. En plus de cela, il convient de souligner que notre protocole de routage étendu utilise un modèle de canal à variation de temps plus réaliste qui tient compte de la plupart des caractéristiques fondamentales de la propagation acoustique sous-marine. Les résultats analytiques montrent que notre protocole de routage assure une réduction importante de la consommation d’énergie. Deuxièmement, pour atténuer les impacts de collision spectaculaires gaspillant l’énergie, nous concevons un protocole MAC multicanal (MC-UWMAC) évitant les collisions pour les UW-ASNs. MC-UWMAC fonctionne avec un canal de contrôle (décomposé en créneaux de temps) et un ensemble de canaux de données à bande passante égale. Les créneaux du canal de contrôle sont dédiés à l’échange RTS / CTS permettant à une paire de capteurs communicants de s'accorder sur l'heure de début de la communication sur un canal de données pré-alloué. Dans cette thèse, nous proposons deux nouvelles procédures associées d'allocation des créneaux du canal de contrôle et d'attribution des canaux de données sans nécessiter de frais de négociation supplémentaires. En conséquence, chaque capteur peut initier l'échange RTS / CTS uniquement à son créneau assigné, calculé à l'aide d'une procédure d'allocation basée sur une partition virtuelle de grille de la zone de déploiement. (...)
UnderWaterAcoustic Sensor Networks (UW-ASNs) are the newest technological achievement in terms of communication. Composed of a set of communicating underwater sensors, UW-ASNs are intended to observe and explore lakes, rivers, seas and oceans. Recently, they have been subject to a special attention due to their great potential in terms of promising applications in various domains (military, environmental, scientific...) and to the new scientific issues they raise. A great challenging issue in UW-ASNs is the fast energy depletion since high power is needed for acoustic communication while sensors battery budget is limited. Hence, energy-efficient networking protocols are of a paramount importance to make judicious use of the available energy budget while considering the distinguishing underwater environment characteristics. In this context, this thesis aims at studying the main challenging underwater acoustic sensors characteristics to design energy-efficient communication protocols specifically at the routing and MAC layers. First, we address the problem of energy holes in UW-ASNs. The sink-hole problem occurs when the closest nodes to sink drain their energy faster due to their heavier load. Indeed, those sensors especially the ones that are 1-hop away from the static sink act as relays to it on behalf of all other sensors, thus suffering from severe energy depletion. In particular, at the routing layer, we propose to distribute the transmission load at each sensor among several potential neighbors, assuming that sensors can adjust their communication range among two levels when they send or forward data. Specifically, we determine for each sensor the set of next hops with the associated load weights that lead to a fair energy depletion among all sensors in the network. Then, we extend our balanced routing strategy by assuming that each sensor node is not only able to adjust its transmission power to 2 levels but eventually up to n levels where n > 2. Consequently, at the routing layer, for each possible value of n, we determine for each sensor the set of possible next hops with the associated load weights that lead to a fair energy consumption among all sensors in the network. Moreover, we derive the optimal number of transmission powers n that balances the energy consumption among all sensors for each network configuration. In addition to that, it is worth pointing out that our extended routing protocol uses a more realistic time varying channel model that takes into account most of the fundamental characteristics of the underwater acoustic propagation. Analytical results show that further energy saving is achieved by our extended routing scheme. Second, to mitigate the dramatic collision impacts, we design a collision avoidance energy efficient multichannel MAC protocol (MC-UWMAC) for UW-ASNs. MC-UWMAC operates on single slotted control and a set of equal-bandwidth data channels. Control channel slots are dedicated to RTS/CTS handshaking allowing a communicating node pair to agree on the start time of communication on a pre-allocated data channel. In this thesis, we propose two novel coupled slot assignment and data channels allocation procedures without requiring any extra negotiation overhead. Accordingly, each node can initiate RTS/CTS exchange only at its assigned slot calculated using a slot allocation procedure based on a grid virtual partition of the deployment area. Moreover, for each communicating pair of nodes, one data channel is allocated using a channel allocation procedure based on our newly designed concept of singleton- intersecting quorum. Accordingly, each pair of communicating nodes will have at their disposal a unique 2-hop conflict free data channel. Compared with existing MAC protocol, MC-UWMAC reduces experienced collisions and improves network throughput while minimizing energy consumption

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24

Carlson, Paul M. (Paul Myron). "Allocating banks of flights to arrivals slots in reduced-capacity situations." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/42629.

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25

Murta, Ana Elizabeth Cavalcanti. "As agências reguladoras : o caso do transporte aéreo no Brasil." Master's thesis, Instituto Superior de Economia e Gestão, 2018. http://hdl.handle.net/10400.5/16783.

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Mestrado em Economia Internacional e Estudos Europeus
O estudo em questão tem como objetivo principal fazer uma análise, sob o ponto de vista da economia de mercado, das medidas adotadas pela Agência Nacional de Aviação Civil (ANAC), esta que exerce o papel como agência reguladora técnica e econômica responsável pelo setor de transporte aéreo no Brasil. Foi realizado um estudo teórico para justificar a adoção de uma agência reguladora independente no âmbito econômico, com o propósito de equilibrar a intervenção do Estado com medidas econômicas que incentivem a concorrência. Em seguida, foi desenvolvido um estudo histórico sobre a aviação aérea civil brasileira. Foram analisados, de maneira abrangente, os principais problemas do mercado atualmente, incluindo: a tendência das companhias brasileiras em adquirir slots, como forma de ativo em aquisições de empresas da própria concorrência; a falta de infraestrutura dos aeroportos e a grave questão da alocação de slots dos aeroportos coordenados. Por fim, também foram analisadas medidas alternativas que a agência vem buscando instalar, para minimizar as barreiras encontradas por novas entrantes, quando estas expressam interesse em investir no setor. Dentro de todo o contexto estudado, foi possível verificar, de forma crítica, os efeitos positivos (e, em algumas situações, negativos) das medidas adotadas pela agência e a sua efetividade (ou não) em garantir a manutenção do mercado e fomentar a competitividade do setor, que sempre foi dominado por uma quantidade limitada de empresas aéreas.
The main objective of this study is to analyze the measures adopted by the National Civil Aviation Agency (ANAC) from the point of view of the market economy. ANAC exercises the role as the technical and economic regulatory agency responsible for the air transport sector in Brazil. A theoretical study was carried out to justify the adoption of an independent regulatory agency in the economic sphere, with the purpose of balancing the state with more liberal economic measures. Thereafter, a historical study about Brazilian civil aviation was developed. The main problems of the market today have been analyzed comprehensively; including the tendency of Brazilian companies to acquire slots as an asset, in acquisitions of companies of competition itself; the lack of airport infrastructure and serious issue of slot allocation at coordinated airports. Finally, it was also analyzed alternative measures that the agency has been seeking to install to minimize the barriers encountered by new entrants when they express interest in investing in the sector. Within all the studied context, it was possible to critically verify the positive (and in some cases, negative) effects of the measures adopted by the agency, its effectiveness in guaranteeing the maintenance of the market and in fostering the competitiveness of the sector, which has always been dominated by a limited number of companies.
info:eu-repo/semantics/publishedVersion

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26

Akbarzadeh, Sara. "Algorithmes distribués d'allocation de ressources dans les réseaux sans fil." Phd thesis, Télécom ParisTech, 2010. http://pastel.archives-ouvertes.fr/pastel-00549417.

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La connectivité totale offerte par la communication sans fil pose un grand nombre d'avantages et de défis pour les concepteurs de la future génération des réseaux sans fil. Un des principaux défis qui se posent est lié à l'interference au niveau des récepteurs. Il est bien reconnu que ce défi réside dans la conception des systèmes d'allocation des ressources qui offrent le meilleur compromis entre l'efficacité et la complexité. L'exploration de ce compromis nécessite des choix judicieux d'indicateurs de performance et des modèles mathématiques. À cet égard, cette thèse est consacrée à certains aspects techniques et mathématiques d'allocation des ressources dans les réseaux sans fil. En particulier, nous demontrons que l'allocation de ressources efficace dans les réseaux sans fil doit prendre en compte les paramètres suivants: (i) le taux de changement de l'environnement, (ii) le modèle de trafic, et (iii) la quantité d'informations disponibles aux émetteurs. Comme modeles mathématiques dans cet étude, nous utilisons la théorie d'optimisation et la théorie des jeux. Nous sommes particulièrement intéressés à l'allocation distribuée des ressources dans les réseaux avec des canaux à évanouissement lent et avec des informations partielles du canal aux émetteurs. Les émetteurs avec information partielle disposent d'informations exactes de leur propre canal ainsi que la connaissance statistique des autres canaux. Dans un tel contexte, le système est fondamentalement détérioré par une probabilité outage non nul. Nous proposons des algorithmes distribués à faible complexité d'allocation conjointe du débit et de la puissance visant à maximiser le "throughput" individuel.

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Amdouni, Ichrak. "Réseaux sans fil auto-adaptatifs: efficacité énergétique et réutilisation spatiale." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2013. http://tel.archives-ouvertes.fr/tel-00808651.

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La nécessité de maximiser la durée de vie du réseau sans fil dans les réseaux ad hoc et en particulier dans les réseaux de capteurs sans fil nécessite l'utilisation d'algorithmes d'efficacité énergétique. Motivée par le fait qu'un noeud consomme le moins d'énergie lorsqu'il est en veille, nous réalisons l'efficacité énergétique vi des algorithmes d'ordonnancement des activités des noeuds. Les noeuds reçoivent des slots temporels durant lesquels ils peuvent transmettre et ils peuvent éteindre leur radio quand ils ne sont ni en train de transmettre, ni en train de recevoir. Par rapport au TDMA classique, l'utilisation de la bande passante est optimisée: deux noeuds interférents ne partagent pas les mêmes slots. Dans notre travail sur l'ordonnancement, deux cas sont étudiés. Tout d'abord, lorsque les nœuds nécessitent le même temps d'accès au canal, nous utilisons le coloriage des nœuds. Deuxièmement, lorsque les nœuds requièrent des débits hétérogènes, nous utilisons une allocation de slots " traffic aware ". Contrairement à la majorité des travaux antérieurs, nous généralisons la définition du coloriage des noeuds et les problèmes d'attribution des slots. En effet, nous considérons que la distance maximale entre deux nœuds interférents est un paramètre de ces problèmes. Nous prouvons qu'ils sont NP-complets, ce qui rend inévitable l'utilisation des heuristiques dans la pratique. Une directive centrale de cette thèse est de concevoir des solutions auto-adaptatives. Cette adaptabilité concerne de nombreux aspects tels que la mission confiée par l'application, l'hétérogénéité des demandes de trafic de nœuds, la densité du réseau, de la régularité de la topologie du réseau, et la non fiabilité des liens sans fil.

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HUNG, HSU-KUAN, and 洪許寬. "Optimization of GPRS Time Slot Allocation." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/40842257186487983475.

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碩士
國立臺灣大學
資訊管理研究所
89
With the maturity of the wireless networks technology, the demands for the mobile communication become higher and higher. Besides voice communication demands, data transmission applications such as WWW, multimedia are becoming more and more important. The main system of mobile communication is GSM, which is mainly designed for voice and is not suitable for data transmission. In order to satisfy the increasing user requirements, in developing of GSM phase 2+, the ETSI has specified a general packet radio service (GPRS) that accommodates data connections with high bandwidth efficiency. Since GPRS is based on GSM and they use the same physical channels, the allocation of time slot is an academic issue. Different slot allocation policy will cause different revenue, throughput and QoS of the system. In the vendor's point of view, revenue maximization is the main consideration. Thus in this thesis, we want to find a policy to maximize the system revenue according to the users' traffic pattern. We propose two mathematical models to deal with the slot allocation problem in this thesis. The goal of our model is to find a slot allocation policy to maximize the system revenue under the capacity constraint. The main difference between two models is the time type. The first model is continuous-time, and the second model is discrete time. We apply Markovian decision process to solve our problem due to the problem size and the mathematical structure of our model. The computational results are good in our experiments. We can find a slot allocation policy to maximize the system revenue according to users' traffic pattern. Comparison to the policy that the vendors often used, the policy we found has great improvement in system revenue. Thus, our model could provide good decisions for system vendors and network planners.

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Santos, Rafael Filipe dos. "Airport Slot Allocation Processes. A heuristic approach." Master's thesis, 2018. https://hdl.handle.net/10216/111114.

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Lobo, Sofia Sousa. "Airport Slot Allocation - instances and resolution methods." Dissertação, 2021. https://hdl.handle.net/10216/133055.

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Lobo, Sofia Sousa. "Airport Slot Allocation - instances and resolution methods." Master's thesis, 2021. https://hdl.handle.net/10216/133055.

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32

Jyh-Rong, Sheu, and 許致榮. "A study on slot reassemby and buffer allocation for different slot reuse schemes." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/06115906593302211394.

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碩士
國立雲林科技大學
電機工程技術研究所
86
Cyclic-Reservation Multiple-Access(CRMA) is an access scheme for high-speed local and metropolitan area networks based on a unique direction, dual-bus configuration. For this network, the slot reuse problem is an important issue, and there has been many literature on it already, therefore, most literature has dwelt on the issue of decreasing cycle lengths, less to discuss botQtot reassembly and buffer allocation under CRMA. On the other hand, workstation buffers are important yet limited resources; therefe, when workstation buffers are insufficient, it can cause failure in reception or composition on the part of data segments, which will result in data loss and reduction of system efficiency. This thesis is then devoted to a discussion of the management problem of buffers of different slot reuse schemes, especially the problem of calculating the size of workstation buffers and the problem of dealing with the insufficiency of workstation buffers. There are two main kinds of reuse in the thesis. One is named continuous slot reuse scheme, and the other one is named non-continuous slot reuse scheme. When the continuous slot scheme is adopted, both problems of the slot reassembly and the buffer size of the workstation needed are easy to solve, but how to find the optimal cycle length for each cycle is NP-complete. When the non-continuous slot reuse scheme is adopted, not only the optimal cycle length can be found in polynomial time, but also the cycle lgth is shorter than the solution of the continuous slot reuse scheme obtained. However, we have discovered that both problems of the slot reassembly and calculating the buffers of workstation needed are complicated when the non-continuous slot reuse scheme is adopted. In this thesis, we will make a comparison to the two main slot reuse schemes by the viewpoint of slot reassembly and the buffer size ofthe workstation needed. In the slot assembly problem, when the continuous slot reuse scheme is adopted, the slot assembly can be finished by modifying the slot format, not necessary to extend each slot length. On the other hand, because the header length of the original CRMA is not sufficient enough, a two bytes length is increased additionally to help the slots reassembly. In the buffer size problem, it is easy to calculate the size of workstation buffers if the continuous slot reuse scheme is adopted. Therefore, under the case of non-continuous reuse, the size of workstation buffers not only increased, but also complicated to calculate. So for the non-continuous slot reuse scheme, we will first of all present a simple upper bound for the size of workstation buffers; second, several efficient algorithms will be proposed to obtain an accurate calculation of the buffer size need for every workstation. In order to realize the buffer size needed for every workstation under the continuous slot reuse scheme and non-continuous slot reuse scheme, some experiments are made. Due to the buffer size of every workstation needed is large under the non-continuous scheme, the insufficiency of workstation buffers might occur. For this question, we also have designed several strategies to cope with the insufficiency of workstation buffers. These strategies fall into two categories which the reserve vectors are rejected by workstations and the other aren*t, furthermore the latter case can divide into the concentration mode and the distribution mode. For each strategy we construe its advtages and drawbacks, and both throughput and MAC delay experiments are made. At last, a comparison and discussion has been made between our simulation results and the case of continuous slot reuse. We have discovered that, even if the management problem of workstation buffers is taken into evaluation standard, non-continuous slot reuse is still superior to the continuous slot reuse in overall performance.

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33

Yao, Chin-Yi, and 姚勤憶. "Slot Allocation Strategy for Clustered Ad Hoc Networks." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/82409995849668432958.

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碩士
國立中山大學
電機工程學系研究所
94
This work studies the allocation of bandwidth resources in wireless ad hoc networks. The highest-density clustering algorithm is presented to promote reuse of the spatial channel and a new slot allocation algorithm is proposed to achieve conflict-free scheduling for transmissions. Since the location-dependent contention is an important characteristic of ad hoc networks, in this paper we consider this feature of ad hoc networks to present a new cluster formation algorithm, by increasing the number of simultaneous links to enhance spatial channel reuse. Furthermore, because each cluster has its own scheduler and schedulers operate independently of each other, the transmissions may conflict among the clusters. In this paper, we classify the flows by the locations of their endpoints to prevent this problem. Finally, the proposed mechanism is implemented by simulation and the results reveal that the conflicts can be efficiently avoided without global information and the network throughput is improved without violating fairness.

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Che, Pei Yu, and 車沛俞. "Optimized Slot Allocation for A Single Liner Service." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/52035552372580649925.

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碩士
國立臺灣海洋大學
航運管理學系
93
While facing increasingly competitive market on ship enlargement and uncertain cargo demands, most liner companies would increase the usage of container space through Slot Allocation so as to maximize the margins for the company. It is expected that slot allocation would be the major strategic issue for those liner companies. However, the study of slot allocation is less discussed on previous literature and academic research. Therefore, in the beginning of the chapters, Single liner service is used as the foundation, and to evaluate the effects of different container allocation, upon either Joint venture or Self-Operation. Among those chapters, slot allocation will be first discussed under Self-Operation business, and go through changing the freight charge and container demands to observe the effects on slot allocation. Secondly, by way of Joint-Operation mode, a mathematical model is constructed to calculate the ideal number of ship dispatch and space commerce. In terms of past literature review and those un-solved questions, this research is aimed at pursuing the maximum profits based on proposing a suitable mathematical model. Those related generators and algorithm were coded in Visual C++ and this CPLEX software is used to provide an adequate solution. This is expected to verify the accuracy and appropriateness of the whole assumption and preset testing model. By comparing the situation upon estimated results and real slot allocation, it would not only help to testify the reliability of this mathematical model; it would also help to figure out the factors that would affect the slot allocation via detailed analysis of the outcome. Upon the cooperation with real business operation, this research is believed to benefit those liner companies by offering a well-calculated model and targeted to raise the profit margins.

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Laura and 陳優蓉. "Slot Allocation Models for Container Shipping with Demand Uncertainty." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/46050712579028318713.

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碩士
國立交通大學
運輸與物流管理學系
104
Similar to the airline industry, the container shipping industry has a very high fixed cost and is thus a potential candidate for the application of revenue management (RM) or yield management (YM). However, in the effort of better utilizing the limited vessel capacity, booking requests are still usually managed by experienced employees without too much decision support in the container shipping industry. Some slot allocation models have been developed to determine the sales quota for a specific market (origin-destination pair). However, demand uncertainty is rarely considered in these decision models. This study develops a linear mathematical programming (LP) model to generate the booking limit for each origin-destination pair, with an uncertain demand represented by a random variable. In addition, the concept of overbooking is further incorporated to develop a modified LP model with over allocation by taking into account the loss due to unused capacity. An iterative approach is designed to successively estimate the opportunity cost of the capacity and re-solve the modified LP model to generate the inflated booking limits. A simulation experiment is performed by generating the booking requests and applying the booking limits. It is found the revenue obtained by the control decision based on the modified model is significantly higher than the one from the basic model or from the first-come-first-served (FCFS) policy.

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Tsan, Yen-Ching, and 昝延慶. "A Slot Allocation Model with Overbooking Sales for Liner Shipping." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/56584163727079649530.

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碩士
國立東華大學
全球運籌管理研究所
97
Using the concept of revenue management, the liner shipping company can reduce the waste of empty slots. The liner shipping company also get more profit by shipping the container type with higher marginal profit. Slot allocation is a very important operational strategy for the liner shipping company. With the unbalance of international container flow, the liner shipping company has to ship empty container to ease off the impact of international unbalanced container. The liner shipping company also uses the strategy of overbooking which has been used for a long time in the air line industry. Ocean lines have used the slot overbooking strategy to lower the loss due to no-shows. This research discusses slot allocation of ocean industry by considering slot overbooking and empty container transshipment using a mathematic model. To deal with the slot overbooking issue, we use mixed integer programming to model the different scenarios of customer show rates. Meanwhile, we provide a strategy to offload heavy containers when the liner shipping company faces the situation which container transshipment quantity over the vessel capacity. In the end, one example is developed to illustrate the mathematic model. Compare to the mathematic model without considering the overbooking element, our model could get more expected profit. With the higher customer no-show rate, the overbooking strategy will have more noticeable effect.

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Lin, Shao-chen, and 林少珍. "Distributed Mini-slot Allocation Algorithm for OFDMA Wireless Mesh Networks." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/54849180454246441057.

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碩士
國立臺灣科技大學
電機工程系
96
The distinguishing characteristic in wireless mesh network (WMN) enhances network capacity and connectivity which makes it one of the necessary technologies in the next generation networks. In particular, the joint of resource allocation to improve system performance has been intensively studied. Beside, orthogonal frequency division multiple access (OFDMA) has been considered as a solution for radio resource insufficiency because OFDMA has high flexibility in terms of resource management. A proper scheduling algorithm and spatial re-use could effectively enhance the throughput of WMN. Firstly, this paper uses the dedicated channel for three-way handshake signaling messages so the number of control frames in OFDMA frame can be greatly reduced to effectively promote throughput. We study the OFDMA system characteristic where the basic mini-slot allocated resource unit is in two-dimension. Then, we propose the distributed mini-slot allocation algorithm (DMAA) can increase system performance and reduce the access delay. Finally, the results of simulation demonstrate that high throughput and low access delay can be achieved with relatively simple mini-slot mapping algorithm.

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38

Cruz, João de Oliveira. "Solving the airport slot allocation problem trough a constraint programming model." Master's thesis, 2019. http://hdl.handle.net/10316/93526.

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Dissertação de Mestrado Integrado em Engenharia Civil apresentada à Faculdade de Ciências e Tecnologia
A atribuição de slots nos principais aeroportos mundiais é efetuada de acordo com as complexas orientações constantes das World Slot Guidelines (WSG) estabelecidas pela International Air Transport Association (IATA). Nos últimos anos, o aumento da procura por parte dos passageiros tem levado à necessidade de maior quantidade de aeronaves, voos e consequentemente mais espaço nos aeroportos, os quais estão a atingir, se é que já não atingiram, o seu limite de capacidade. A comunidade científica tem investido no desenvolvimento de modelos e algoritmos de otimização para realizar a atribuição de slots de acordo com as orientações referidas. Este desenvolvimento tem sido acompanhado pelo crescimento evidente na área de computação e linguagem de programação que tem assim oferecendo novas ferramentas aplicáveis à resolução deste problema.A presesente dissertação insere-se no esforço de desenvolvimento de novas abordagens de otimização para a atribuição de slots nos aeroportos mais congestionados. Para tal, apoiar-se-á num novo modelo de por restrições. O desenvolvimento e aplicação deste modelo foram efetuados tendo por referência o modelo de otimização (ou programação) inteira-mista PSAM (Priority-based Slot Allocation Model), desenvolvido no Departamento de Engenharia Civil da Universidade de Coimbra. Este trabalho teve como objetivo a comparação, em termos de capacidade e velocidade de processamento, do modelo proposto com o referido acima, modelo esse que foi resolvido por um método de branch-and-cut.O trabalho realizado inseriu-se no projeto ASAP (Airport Slot Allocation Process), atualmente em curso na Universidade de Coimbra. Contou ainda com a colaboração da entidade coordenadora de slots de França, COHOR e com a École Nationale d’Aviation Civile (ENAC) através da realização de um estágio no grupo de investigação em otimização, que se dedica maioritariamente a modelos de otimização aplicados a problemas relacionados com a aviação.
The slot allocation process at major airports worldwide occurs in compliance with the World Slot Guidelines (WSG) established by the International Air Transport Association (IATA). Over the last few years, the general increase of demand from passengers led to the need for more aircraft, more flights and consequently more space at the airports which are reaching or already passing their capacity limit. The scientific community has been working on the development of models and optimization algorithms to perform the slot allocation in compliance with the guidelines referred above. This development has been supplemented by the growth in computing and programming language that has been offering new tools applicable to this problem.This dissertation is part of the effort to develop new approaches to slot allocation in the most congested airports. To do so, it will rely on a new constraint model. The development and application of this model having as a reference the PSAM (Priority-base Slot Allocation Problem) model, developed at the Department of Civil Engineering of the University of Coimbra. The objective was to compare the model now proposed with this other model which was solved by a branch-and-cut method, in terms of processing capacity and speed to obtain optimal slot allocation solutions.The work was carried out as part of the ASAP (Airport Slot Allocation Process) project, currently underway at the University of Coimbra, with the collaboration of the French slot coordinator entity COHOR and the École Nationale d'Aviation Civile (ENAC) which provided an internship with the optimization research group that mainly devote their work to aviation optimization practice.

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CHUANG, HUI-TING, and 莊惠婷. "Optimization of GPRS Time Slot Allocation Considering Call Blocking Probability Constraints." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/54202451602068361393.

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碩士
國立臺灣大學
資訊管理研究所
90
GPRS is a better solution to mobile data transfer before the coming of 3G network. By using packet-switched technique, one to eight time-slot channels can be dynamically assigned to GPRS users on demand. Because GSM and GPRS users share the same channels and resources, the admission control of different type of traffics is needed to optimize the data channel allocation. The methodology of dynamic slot allocation plays an important role on both maximizing the system revenue and satisfying users’ QoS requirements. We try to find out the best methodology to get the maximum system revenue considering the call blocking probability constraints. We propose two mathematical models to deal with the slot allocation problem in this thesis. The goal of our model is to find a slot allocation policy to maximize the system revenue considering the capacity and the call blocking probability constraints. The main difference between two models is the time type. The first model is discrete-time case, and the other is continuous-time case. Markovian decision process can be applied to solve the problem of maximizing system revenue without the call blocking probability constraints. In order to take the call blocking probability constraints into account, we propose three approaches: linear programming in Markovian decision process, Lagrangian relaxation with Markovian decision process, and the expansion of the Markovian decision process. The most significant and contributive part of this thesis is that we combine the Lagrangian relaxation and the Markovian decision process and use it to successfully solve the Markovian decision process with additional constraints. The computational results are good in our experiments. We can find a slot allocation policy to maximize the system revenue under the call blocking probability constraints. Compared to the policy that the vendors often used, the policy we found has great improvement in system revenue. Thus, our model could provide much better decisions for system vendors and network planners.

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Lai, Ching-Jung, and 賴清榮. "Optimized slot allocation analysis for liner services under an alliance agreement." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/99399766634937010608.

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Wang, Jian-Kai, and 王建凱. "A Cluster-based Slot Allocation Adjusting Protocol for Wireless Sensor Networks." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/54461816569032282069.

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碩士
元智大學
資訊工程學系
94
Wireless sensor networks typically consist of a large number of low cost sensor nodes, which can collaborate among each other to enable a wide range of applications such as environmental monitoring, intrusion detection and disaster management … etc. Since the sensor nodes must sense and transmit data for a long period of time, wireless sensing devices are seriously restricted by their limited energy supply. Therefore, many researchers are working on how to manipulate the sensor nodes energies efficiently and extend the whole network lifetime. The issues of fairness and delay time are relatively not so important. In this paper, we will develop a TDMA based Medium Access Control (MAC) mechanism on cluster infrastructure to achieve the maximum power saving. Through adjusting time slot allocation in advance, our mechanism tries to avoid the collisions resulting from the transmissions between clusters as much as possible. Then, we may reduce a lot of energy consumption on retransmitting. Finally, through the MAC protocol coupled with TDMA, each sensor node may wake up at the fixed time slot and turn into the sleep mode for a long time. Therefore, our mechanism will save the energies efficiently and extend the whole network lifetime.

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鄭如吟. "The Study on Slot Allocation Decision Analysis for the Liner Shipping Industry." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/43794136075979612583.

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Shih, Ting-Wen, and 施婷文. "Determinants of Consignment Acceptance and Slot Resource Allocation for Sea Freight Forwarders." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/30589269214139279319.

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碩士
國立臺灣海洋大學
航運管理學系
101
Sea freight forwarders face a keen competition and complicated market, but they are not necessarily inspect the available resources at hand. This study discusses the relationship between consignment acceptance of sea freight forwarders and slot allocation from carriers, expecting to verify those factors and put the results in practical use. Previous studies only focus on how shippers choose carriers, and how carriers’ slot allocation affect shippers’ decisions, but few studies discusses the critical role of sea freight forwarders between shippers and carriers. Namely, we hardly find the studies focusing on how shippers choose forwarders, and how carriers’ slot allocation affects forwarders’ decisions. Hence, this study collects sufficient data from experienced forwarders, using centroid of grey interval and fuzzy cognitive maps, concluding the key factors among forwarders with different operational scale. This study indicates that (1) the top three factors to forwarders’ acceptance are “shippers’ credibility record”, “dangerous cargo or not”, and “the possibility of cargo damage”. (2) the top three factor to choosing carriers are “professional knowledge of carriers’ sales”, “speed to solve problems and complaints”, and “ocean freight”. (3) when choosing shippers, forwarders with operation volume 500 teus and below focuses on “shippers’ credibility record”; forwarders with 501-1000 teus focuses on “slot sufficiency”; forwarders with 1001-1500 teus focuses on “shippers’ credibility record”; forwarders with 1001 teus and above focuses on “dangerous cargo or not”. (4) when choosing carriers, forwarders with operation volume 500 teus and below focuses on “ocean freight”; forwarders with 501-1000 teus focuses on “reliability of shipping schedule”; forwarders with 1001-1500 teus focuses on “ocean freight”; forwarders with 1001 teus and above focuses on “professional knowledge of carriers’ sales”. (5) the determinants of consignment acceptance and slot resource allocation for sea freight forwarders are “dangerous cargo or not”, and “professional knowledge of carriers’ sales”.

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Lu, Po-Hsueh, and 呂柏學. "Time Slot allocation for Improving Energy-Efficiency in Multi-hop Layered WSN." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/25511881499248368048.

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碩士
國立中山大學
電機工程學系研究所
99
Advances in micro-sensor and wireless technology enable small but smart sensors to be developed for wide range environment-monitor applications. Since Sensor nodes only have limited power capacity and are difficult to recharge, how to prolong network lifetime is an important issue in wireless sensor networks design. Several topology control algorithms have been proposed to maintain the connectivity of wireless sensor network and reduce the energy consumption. Multi-hop Infrastructure Network Architecture (MINA) is a kind of Multi-layer Architecture for WSN topology, which utilizes hundred of sensors to transmit data to a sink. This architecture partitions sensor nodes into layers based on their distances (calculated by hop count) to BS. In this way, the node connected to more nodes will relay more data for other nodes. This make the node exhaust its battery power quickly and thus reduces the network lifetime. This study proposes an Efficient Energy Time-Slot Allocation (EETA) scheme which distributes time slots in accordance with the energy of neighbor nodes and the number of neighbor nodes. In addition, this work also devises an adaptive time slot size to reduce data packet drop in case when the node buffer is full. The simulation results show that the EETA performs better than the MINA in terms of network lifetime.

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Ken, Yiu-Ming, and 耿佑銘. "Determinants of Consignment Acceptance and Slot Resource Allocation for Air Freight Forwarder." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/33961011625635974878.

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碩士
國立臺灣海洋大學
航運管理學系
102
Nowadays, international trade liberalization and the rapid development of global supply chains, making the growing demand for air freight cargo transportation. Air Freight cargo typically have high timeliness and high-priced properties, coupled with fierce competition among peers, in this case, air freight forwarders operating services for very high quality requirements. Air freight forwarders who offer services for shippers, while the other hand is also airlines’ consumer, it plays a very important role in the whole process of air cargo market. In this study, a questionnaire survey method to Taiwan air freight forwarders as research subjects, with fuzzy cognitive maps as the basic framework, mainly in the investigation of air freight cargo forwarders whether to accept shippers’ commissions as the key decision factors; and the key decision factors of air freight forwarders consign airlines space. To obtain industry perception of importance of various factors from forwarders, and compiled an index of importance of the different scale of operation, hope to provide the reference for the industry and future researchers. If the key factors could be clarified, it will be able to assist in air freight forwarder in Practice analysis and theoretical studies. The following descriptions obtained by this study and made recommendations based on the results, as the reference for future researches. The major findings in this research include: (1) the top three factors to forwarders’ acceptance are “shippers’ credibility record”, “goods can be brought profit to the company."”, and “shippers’ payment time is too long or not”; (2) the top three factor to choosing airlines are “the ability of emergencies handling for airlines”, “the right time scheduled of airlines”, and “the publicity and image of airlines”.; (3) when choosing shippers, forwarders with operation volume 500 tons and below focuses on “goods can be brought profit to the company”; forwarders with 501-800 tons focuses on “goods can be brought profit to the company”; forwarders with 801-1000 tons focuses on “Whether the destination of the goods have space available for delivery”; forwarders with 1001 tons and above focuses on “The owner has records of bad credit previously or not”; (4) when choosing carriers, forwarders with operation volume 500 tons and below focuses on “the ability of emergencies handling for airlines”; forwarders with 501-800 tons focuses on “Airlines could quickly solve customers’ complain effectively”; forwarders with 801-1000 tons focuses on “the difficult to obtained space for airlines”; forwarders with 1001 tons and above focuses on “the publicity and image of airlines”.; (5) the determinants of consignment acceptance and slot resource allocation for air freight forwarders are “goods can be brought profit to the company”, and “airline transport reliability”.

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Chung, Sung-Hsi, and 鍾松錫. "Interference Analysis and Time Slot Allocation Scheme in the CDMA/TDD System." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/27140087919447145608.

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碩士
國立成功大學
電機工程學系碩博士班
92
The key advantage of CDMA/TDD system is to accommodate asymmetric traffic by allocating number of uplink and downlink channels. Because both uplink and downlink use the same frequency band in each cell, the different time slot allocation between each cell will causes severe multiusers' interference in the TDD system. If we combine cellular system with directional antenna technique, the directivity of directional antennas can provide an additional degree of freedom for allocating radio resource and improve the system capacity. 　　In this thesis, we provide exact analysis of interference (include the MS-MS, BS-BS and MS-BS interference) according to the different traffic patterns between adjacent cells. From the analytic results, we propose a proper time slot allocation scheme to avoid the multiusers' interference between time slots from neighboring cells and increase the utilization of the radio resource. Then the analytic results are verified by simulation.

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Ribeiro, Nuno Antunes. "Airport capacity management: towards a slot allocation modelling approach compliant with IATA rules." Doctoral thesis, 2019. http://hdl.handle.net/10316/87612.

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Tese de Doutoramento em Sistemas de Transporte, apresentada ao Departamento de Engenharia Civil da Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Air traffic demand has grown to exceed available capacity during extended parts of each day at many of the busiest airports in the world. Absent opportunities for capacity expansion, this may require the use of demand management measures to restore the balance between scheduled traffic and available capacity. The main demand management mechanism in use today is the administrative slot allocation process operated by the International Air Transport Association (IATA), which is in place at the great majority of the busiest airports outside the United States. At these airports, airlines need to be assigned slots by a slot coordinator to schedule their flights. Slot allocation is driven by a set of rules and priorities specified in the IATA Worldwide Slot Guidelines (WSG). These rules introduce coupling constraints across the allocation of slots at multiple times of the day and multiple days of the year, resulting in a highly complex combinatorial problem that carries enormous weight for airlines, airports and passengers. In recent years, integer programming models have been proposed to support slot allocation by minimizing deviations from the airlines’ requests. However, due to the problem’s complexity, these models have been only successfully implemented at small size airports (up to 50,000 flights per year). In this thesis, we develop an original modelling approach aimed to advance existing slot allocation tools and procedures at the largest airports in the world. For that purpose, we formulate a novel integer programing model of slot allocation fully compliant with the WSG rules. The model – named Priority-based Slot Allocation Model (PSAM) – develops an original and efficient mathematical formulation that enables its implementation using exact optimization methods at airports at least with twice the size as previously considered. In order to solve the slot allocation problem at the busiest airports in the world, we also develop an algorithmic approach based on large-scale neighborhood search heuristics. The proposed algorithm combines a constructive heuristic to provide an initial feasible solution in short computational times, and an improvement heuristic that iteratively re-optimizes slot allocation by subdividing the slot requests into smaller subsets. Experimental results show that the algorithm proposed can provide optimal, or near-optimal solutions, in a few hours of computation in instances where direct implementation of PSAM with commercial solvers does not terminate after several days of computation. The modelling approach proposed in this dissertation was implemented at three Portuguese airports, a small one (Madeira), a mid-size one (Porto) and a large one (Lisbon), using highly detailed data on airline slot requests and airport capacity constraints. Results suggest that its implementation in support of slot allocation at major slot-coordinated airports worldwide can result in flight schedules that match better airlines’ requests and passenger demand. Equally important, the modelling approach developed in this dissertation can also be used to quantify the sensitivity of slot allocation decisions to the various priorities and requirements specified in the WSG. This allowed us to evaluate the impact of potential changes in the current slot allocation rules and procedures. Results obtained from many sensitivity analyses performed using PSAM show that adding even limited flexibility to the WSG can, on its own, bring considerable benefits in the short term to the slot allocation process.
A procura pelo tráfego aéreo tem aumentado nos aeroportos mais movimentados do mundo, ao ponto de superar a capacidade neles disponível durante longos períodos do dia. Na ausência de possibilidades de expansão, é essencial recorrer a medidas de gestão de procura para restabelecer o equilíbrio entre o número de voos calendarizados e a capacidade disponível no aeroporto. A principal medida de gestão de procura utilizada consiste no processo de atribuição de slots da Associação Internacional de Transportes Aéreos (IATA). De acordo com este processo, qualquer companhia aérea que pretenda operar um voo num aeroporto coordenado terá de obter antecipadamente uma permissão para a hora em que deseja que a aterragem ou descolagem do voo tenha lugar. O processo de atribuição de slots é regido por um conjunto de regras e prioridades que estão definidas nas IATA Worldwide Slot Guidelines (WSG). Estas regras introduzem um conjunto de restrições que tornam o problema de atribuição de slots bastante complexo. Nos últimos anos, vários modelos de programação inteira foram desenvolvidos com o intuito de auxiliar os coordenadores de slots a otimizar as suas decisões. No entanto, devido à complexidade do problema, estes modelos apenas podem ser eficazmente implementados em aeroportos de pequenas dimensões (até 50,000 voos por ano). Nesta tese é desenvolvida uma abordagem de modelação destinada a melhorar os procedimentos utilizados na atribuição de slots em aeroportos de grandes dimensões. Com esse propósito, é formulado um modelo de programação inteira de atribuição de slots totalmente compatível com as regras especificadas nas WSG. O modelo, denominado Priority-based Slot Allocation Model (PSAM), utiliza uma formulação matemática eficiente que permite a respetiva implementação através de métodos exatos de otimização em aeroportos com o dobro (ou mesmo mais) das dimensões previamente consideradas na literatura. No sentido de resolver o problema da atribuição de slots em aeroportos de ainda maiores dimensões é também desenvolvido um algoritmo aproximado que se baseia em heurísticas de large-scale neighborhood search. O algoritmo proposto combina uma heurística construtiva, utilizada para gerar solução iniciais admissíveis, e uma heurística de melhoramento, utilizada para melhorar essas soluções iterativamente. Os resultados experimentais da aplicação destas heurísticas mostram que o algoritmo proposto fornece, em poucas horas de computação, soluções ótimas ou muito próximas das ótimas quando a implementação direta de PSAM utilizando software comercial de otimização não fornece a solução ótima após vários dias de computação. A abordagem de modelação proposta nesta dissertação foi implementada em três aeroportos portugueses, nomeadamente um aeroporto de pequena dimensão (Madeira), um de média dimensão (Porto) e um de grande dimensão (Lisboa). Os estudos de caso analisados foram sustentados por dados detalhados referentes aos pedidos de slots feitos pelas companhias aéreas para esses aeroportos. Os resultados obtidos sugerem que a abordagem de modelação desenvolvida nesta tese pode auxiliar o coordenador de slots a tomar melhores decisões, nomeadamente encontrando soluções que se aproximam mais dos interesses das companhias aéreas e dos passageiros. Igualmente importante, a abordagem de modelação proposta nesta dissertação pode ser utilizada com o intuito de avaliar o impacto de pequenas alterações às regras existentes de atribuição de slots especificadas nas WSG. Resultados obtidos através de várias análises de sensibilidade realizadas usando o PSAM mostram que mesmo pequenas alterações podem, por si só, trazer no curto prazo consideráveis benefícios ao processo de atribuição de slots.

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Tsai, Pei-chi, and 蔡沛圻. "A study on the allocation of the airport time slot for the domestic flight." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/10354108572479691145.

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碩士
國立交通大學
交通運輸研究所
85
Under the limitation of the airport capacity, except expanding the airport facilities we can also reduce the unfavorable effect of flight delay during peak hours by effective management of the time slot. Current domestic allocation rule is mainly according to the "absolute priorities" and it doesn''t consider the requirement and standpoints of the airport, airlines and passengers; therefore, this study compares the merits and defects of some prevailing allocation rules and takes into account the viewpoints of the three major members of air transportation system (airport, airlines and passengers). Basing on the stability of schedule, capacity of airport, rights of passengers, operational performances of airlines, rights of the newcome and existing airlines, we select seven reasonable criteria for the allocation of time slot. They are grandfather rights, demand of each route, seats of the airplane, load factor, safety records of flying , on-time performance, efficiency of using time slot, respectively.In order to satisfy the "justice" and "reasonableness", this study design a new mode for time slot allocation-"two-stage method". In the first stage, the newcomers of time slot will obtain time slots only when they have better operational performances; besides, they will gain better "time point" in the second stage. As for those who have grandfather rights but don''t have good operational performances will not get the better time points in the second stage and their grandfather rights will decrease by season. Those who have grandfather rights and perform well will keep their original grandfather rights; furthermore, they will increase more time slots. Such an allocation mechanism can push airlines to improve their operational performances and consequently promote the service quality of air transportation.

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Hsu, Ching-wen, and 許瀞文. "Optimal decision to containership slot allocation and empty container repositioning for global container carriers." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/56263890745089136208.

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碩士
淡江大學
資訊管理學系碩士在職專班
101
Due to over-supply of capacity and imbalance trades between areas, carriers encounter increasing costs and operational difficulties. Since it is less likely to increase the revenue in the given market, how to efficiently utilize the available slots and decrease operating costs have become the challenges of carriers. The goal of this study is to establish a slot allocation and empty containers reposition model to maximize the carrier’s profit. Factors considered in the model include the lifting of full containers, the routing of full containers, sources of container supply, empty container reposition, etc. To evaluate the performance of the proposed approach. Five performance indicators regarding the operations of a containership are used, including container safety stock, Customer demand satisfaction, Container idle time, Proportion of space and container supply and Vessel Space utilization rate.

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Chang, Chia-Hui, and 張嘉惠. "Optimization of Containership Slot Allocation and Empty Container Reposition for a Short-Sea Container Carrier." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/41533506468113846149.

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博士
國立交通大學
交通運輸研究所
97
Container carriers gain freight revenue by delivering containers from one port to another and depend on shipping agencies to provide cargo. Since a fully loaded carrier brings immediate revenue that is higher than that of a partially loaded carrier, cargo flow and freight revenue management are often ignored. To improve their own revenue, which is supplemented by commissions from ocean freight, shipping agencies typically compete for additional slots on containerships. In booming markets, arguments over slot allocation between shipping agencies occur frequently. These disputes, when coupled with the mismanagement of freight revenue on the part of containerships, often result in a loss of revenue for both shipping agencies and carriers. Container carriers tend to accumulate a large number of unnecessary empty containers at particular ports while other ports face a shortage of empty containers. In practice, carriers often reposition a considerable number of empty containers to others ports with shortage, during a single voyage. However, the operational expenses are substantial when an accumulation of this sort occurs. Empty containers also occupy slots on containerships with the result that carriers are unable to take aboard loaded containers yielding freight revenue. In order to increase their competitive edge, container carriers need to manage revenue and control expenditures. Several studies have been conducted on slot allocation and empty container management. A few of these studies have sought to maximize profits on short-sea, multiple-port service routes by considering the cost of empty container repositioning. Little attention has been paid to the management of such repositioning within the sea transportation network. This study, which focuses on short-sea service intra-Asian routes, focuses on both aspects of repositioning. The main characteristics of intra-Asian service routes include: voyage distance is short, there are multiple-port calls, and loading and unloading is frequent at each port. These observations are factored into this study which is divided into two parts. The first part incorporates the concept of revenue management with expected cost of empty container repositioning, by offsetting cargo imbalance. Here an optimal model has been formulated via linear programming to maximize operational profit, subject to the constraints of vessel capacity, vessel deadweight, and container demand. A Taiwan container carrier has been used as a case study. The analytical results show that by implementing the proposed model, containerships can increase profits and shipping agencies might avoid friction in a booming market. The second part of this study proposes to partition the sea transportation network into several geographical regions and distribute empty containers within a single region, in order to reduce the number of occupied slots over a long distance. There are two challenges to this proposal. The first challenge, which is termed the “upper-problem,” lies in identifying and estimating empty container stock for each port. The second challenge or “lower-problem” concerns incorporating modes of transportation into the model. The empty container reposition model that is deemed optimal has been formulated via linear programming with a view to overcoming the transportation problem and minimizing the total cost of transferences within a single region. Here again, the research uses data obtained from a Taiwan container carrier. When this data is applied for analysis, the results show that the allocation of empty containers can be optimized by repositioning them over the course of several voyages where they can occupy unsold slots. With regard to port characteristics, this study proposes the following strategies to solve empty container problems: charter slots, launching a containership for extra service, or introducing a temporary change in the service route. These are all short-term solutions. In the long-term, sea ports might need to restructure their sea transportation network.

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Dissertations / Theses on the topic 'Slot allocation'

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