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Ustunel, Eser Kwon Hyuck M. "Time division duplex-wideband code division multiplex (TDD-WCDMA)." Diss., Click here for available full-text of this thesis, 2006. http://library.wichita.edu/digitallibrary/etd/2006/t029.pdf.
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Thesis (M.S.)--Wichita State University, Electrical and Computer Engineering.<br>"May 2006." Title from PDF title page (viewed on October 19, 2006). Thesis adviser: Hyuck M. Kwon. Includes bibliographic references (leaves 40-42).
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Coey, Tyson Curtis. "Round-trip time-division distributed beamforming." Link to electronic thesis, 2007. http://www.wpi.edu/Pubs/ETD/Available/etd-071007-124515/.
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Cheng, Zhuo. "Hybrid Power Control in Time Division Scheduling Wideband Code Division Multiplex Access." Thesis, KTH, Kommunikationssystem, CoS, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-91097.
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With high date rates using Enhanced Uplink (EUL), a conventional signal to interference ratio (SIR) based power control algorithm may lead to a power rush due to self interference or incompatible SIR target [2]. Time division (TD) scheduling in Wideband Code Division Multiplex Access (WCDMA) is considered to be a key feature in achieving high user data rates. Unfortunately, power oscillation/peak is observed in time division multiplexing (TDM) at the transition between active and inactive transmission time intervals [1]. Therefore there is a need to revisit power control algorithms for different time division scheduling scenarios. The objective of power control in the context of this study is to minimize the required rise over thermal noise (RoT) for a given data rate, subject to the constraint that the physical layer control channel quality is sufficient (assuming that the dedicated physical control channel (DPCCH) SIR should not go below 3dB with a probability of at most 5%). Another goal is to minimize the local oscillation in power (power peaks) that may occur, for example due to transitions between active and inactive transmission time intervals. The considered hybrid power control schemes are: (1) non-parametric Generalized rake receiver SIR (GSIR) Inner Loop Power Control (ILPC) during active transmission time intervals + Received Signal Code Power (RSCP) ILPC during inactive transmission time intervals and (2) RSCP ILPC during active transmission time intervals + GSIR ILPC during inactive transmission time intervals. Both schemes are compared with pure GSIR and pure RSCP ILPC. Link level simulations with multiple users connected to a single cell show that: The power peak problem is obviously observed in GSIR + GSIR transmit power control (TPC), but in general it performs well in all time division scenarios studied. GSIR outperforms other TPC methods in terms of RoT, especially in the TU channel model. This is because it is good in combating instantaneously changed fading and accurately estimates SIR. Among all TPC methods presented, GSIR + GSIR TPC is best in maintaining the quality of the DPCCH channel. No power rush is observed when using GSIR + GSIR TPC. RSCP + RSCP eliminates the power peak problem and outperforms other TPC methods presented under the 3GPP Pedestrial A (pedA) 3km/h channel in terms of RoT. However, in general it is worse in maintaining the control channel’s quality than GSIR + GSIR TPC. GSIR + RSCP ILPC eliminates the power peak problem and out-performs GSIR power control in the scenario of 2 and 4 TDM high data rate (HDR) UE and 2 TDM HDR UE coexistence with 4 Code DivisionMultiplex (CDM) LDR UE, in the pedA 3km/h channel, in terms of RoT. However, the control channel quality is not maintained as well during inactive transmission time intervals. It is not recommended to use RSCP + GSIR TPC since it performs worst among these TPC methods for most of the cases in terms of RoT, even though it is the second best in maintaining the control channel quality. The power peak is visible when using RSCP + GSIR TPC. To maintain the control channel’s quality, a minimum SIR condition is always used on top of all proposed TPC methods. However, when there are several connected TDM HDR UEs in the cell, results indicates that it is challenging to meet the quality requirement on the control channels. So it may become necessary to limit the number of connected terminals in a cell in a time division scenario.<br>Med den höga datahastighet som Enhanced Uplink (EUL) medger kan en konventionell algoritm för effektkontroll baserad på signal to interference ratio (SIR) leda till effekthöjning beroende på självinterferens eller felaktigt SIR mål. Time division (TD) schedulering vid Wideband Code Division Multiple Access (WCDMA) anses vara en nyckelfunktion för att uppnå höga datahastigheter. I övergången mellan aktiv och inaktiv transmissionstidsintervall vid time division multiplexing (TDM) har effektoscillering/effektpeak observerats. Detta gör det nödvändigt att se över algoritmerna för effektkontroll vid olika scenarion av TD schedulering. Målet med effektkontrollen i denna studie är att minimera rise over thermal noise (RoT) för en given datahastighet givet begränsningen att kvaliteten på physical layer control channel är tillräcklig (beaktande att dedicated physical control channel (DPCCH) SIR inte understiger 3dB med en sannolikhet på som mest 5%). Ett annat mål är att minimera den lokala effektoscillationen (effektpeakar) som kan inträffa till exempel vid övergång mellan aktiv och inaktiv transmissionstidsintervall. De undersökta hybrida metoderna för effektkontroll är: (1) icke-parametrisk Generalized rake receiver SIR (GSIR) Inner Loop Power Control (ILPC) vid aktiv transmissionstidsintervall + Received Signal Code Power (RSCP) ILPC vid inaktiv transmissionstidsintervall och (2) RSCP ILPC under aktiv transmissionstidsintervall + GSIR ILPC under inaktiv transmissiontidsintervall. Båda metoderna jämförs med ren GSIR och ren RSCP ILPC. Länk nivå simulering med flera användare anslutna till en enda cell visar att: Problemet med effektpeakar observeras tydligt vid GSIR + GSIR transmit power control (TPC) men generellt sett presterar den bra i alla studerade TD scenarion. GSIR presterar bättre än andra TPC metoder beträffande RoT, speciellt i TU kanal modellen. Detta beror på att metoden är bra på att motverka momentant förändrad fading och med god precision estimerar SIR. Bland alla presenterade TPC metoder är GSIR + GSIR TPC den bästa på att behålla en god kvalitet på DPCCH kanalen. Ingen effekthöjning har observerats vid GSIR + GSIR TPC. RSCP + RSCP eliminerar problemet med effektpeakar och presterar bättre än andra TPC metoder presenterade under 3GPPs Pedestrial A (pedA) 3km/h kanal beträffande RoT. Dock är metoden generellt sett sämre på att behålla kontrollkanalens kvalitet än GSIR + GSIR TPC. GSIR + GSIR ILPC eliminerar problemet med effektpeakar och presterar bättre än GSIR power control i ett scenario med 2 och 4 TDM high data rate (HDR) UE och 2 TDM HDR UE tillsammans med 4 Code Division Multiplex (CDM) LDR UE i pedA 3km/h kanalen beträffande RoT. Dock kan inte kvaliteten på kontrollkanalen behållas i detta fall heller under inaktiv transmissionstidsintervall. Det är inte rekommenderat att använda RSCP + GSIR TPC eftersom den presterar sämst av alla TPC metoder beträffande RoT i de allra flesta fall. Till dess fördel är att den är den näst bästa på att behålla kvaliteten på kontrollkanalen. Effektpeakar har observerats när RSCP + GSIR TPC använts. För att behålla kontrollkanalens kvalitet används alltid en minimum SIR nivå ovanpå alla föreslagna TPC metoder. När det finns flera anslutna TDM HDR UEs i cellen indikerar resultaten att det är en utmaning att behålla kvalitetskraven på kontrollkanalen. På grund av detta kan det bli nödvändigt att begränsa antalet anslutna terminaler i en cell i ett TD scenario.
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Swift, Graham. "Modelling of an optical time division demultiplexer." Thesis, Sheffield Hallam University, 1997. http://shura.shu.ac.uk/20412/.
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The communication Networks of the future will require signal switching in the optical domain to avoid the inherent speed bottleneck of optical-electronic-optical conversions. This has resulted in an intense research effort in this area. Of particular interest are wavelength division multiplexing (WDM) and optical time division multiplexing (OTDM). The latter offers the advantage that it operates over a single wavelength, removing the problems associated with dispersion in fibre systems whilst the former operates over a number of wavelengths. This thesis concentrates on the modelling and simulation of one particular system: the asymmetric semiconductor laser amplifier loop mirror (ASLALOM) for OTDM.Initially, a literature review looks at the theory of laser operation which complements the following chapter on laser amplifiers. A review of current optical switching devices will be examined next with regard to switching speeds, crosstalk and the possibility of integration. Also wavelength division multiplexing and time division multiplexing are reviewed, comparing the different systems in current use. At the present time, no complete models of an asymmetric semiconductor laser amplifier loop mirror have been developed. The intention of this work is to determine the equations necessary for a model to be developed and thus enable the system to be simulated. Computer modelling of a system prior to implementation is advantageous in all aspects of engineering. As this system is still confined to the laboratory a model would complement any practical work and identify critical design parameters. In this work the Travelling Wave Semiconductor Laser Amplifier (TWSLA) is first modelled in a form which is appropriate for the asymmetric semiconductor laser amplifier loop mirror architecture. The simulations are then used to demonstrate the switching speeds for different configurations and identify any areas needing further work, such as crosstalk, birefringence and polarisation, a method for multi-channel output is also presented. A further aim is to lay a foundation for future work to enable the system to be fully characterised with regard to noise, dispersion and integration.
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Brown, Trevor Junior. "Time division multiple access/code division multiple access for the optical local access network." Thesis, Manchester Metropolitan University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243716.
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Muñiz, Rodríguez Marco Antonio [Verfasser], and Andreas [Akademischer Betreuer] Podelski. "Model checking for time division multiple access systems." Freiburg : Universität, 2015. http://d-nb.info/1119327458/34.
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Khan, Adnan Umar. "Distributive time division multiplexed localization technique for WLANs." Thesis, De Montfort University, 2012. http://hdl.handle.net/2086/7102.
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This thesis presents the research work regarding the solution of a localization problem in indoor WLANs by introducing a distributive time division multiplexed localization technique based on the convex semidefinite programming. Convex optimizations have proven to give promising results but have limitations of computational complexity for a larger problem size. In the case of localization problem the size is determined depending on the number of nodes to be localized. Thus a convex localization technique could not be applied to real time tracking of mobile nodes within the WLANs that are already providing computationally intensive real time multimedia services. Here we have developed a distributive technique to circumvent this problem such that we divide a larger network into computationally manageable smaller subnets. The division of a larger network is based on the mobility levels of the nodes. There are two types of nodes in a network; mobile, and stationery. We have placed the mobile nodes into separate subnets which are tagged as mobile whereas the stationary nodes are placed into subnets tagged as stationary. The purpose of this classification of networks into subnets is to achieve a priority-based localization with a higher priority given to mobile subnets. Then the classified subnets are localized by scheduling them in a time division multiplexed way. For this purpose a time-frame is defined consisting of finite number of fixed duration time-slots such that within the slot duration a subnet could be localized. The subnets are scheduled within the frames with a 1:n ratio pattern that is within n number of frames each mobile subnet is localized n times while each stationary subnet consisting of stationary nodes is localized once. By using this priority-based scheduling we have achieved a real time tracking of mobile node positions by using the computationally intensive convex optimization technique. In addition, we present that the resultant distributive technique can be applied to a network having diverse node density that is a network with its nodes varying from very few to large numbers can be localized by increasing frame duration. This results in a scalable technique. In addition to computational complexity, another problem that arises while formulating the distance based localization as a convex optimization problem is the high-rank solution. We have also developed the solution based on virtual nodes to circumvent this problem. Virtual nodes are not real nodes but these are nodes that are only added within the network to achieve low rank realization. Finally, we developed a distributive 3D real-time localization technique that exploited the mobile user behaviour within the multi-storey indoor environments. The estimates of heights by using this technique were found to be coarse. Therefore, it can only be used to identify floors in which a node is located.
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Bouziane, R. "Real-time optical orthogonal frequency division multiplexing transceivers." Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1383794/.
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Optical orthogonal frequency division multiplexing (O-OFDM) is a potential candidate for 100 Gigabit Ethernet (GbE) and beyond due to its high spectral efficiency and strong resilience towards chromatic and polarization mode dispersion. In this thesis, investigations have been performed into the feasibility of O-OFDM in high speed optical fibre communications. First, an overview of OFDM fundamentals and optical fibre communications is given. Numerical simulations which were performed to characterise and optimise real-time OFDM transceivers are then presented. The effects of a variety of design parameters on the performance of the system are studied. Amongst the key parameters included in the study are the quantisation and clipping noise in data converters, and the quantisation errors in the fast Fourier transform and its inverse (FFT/IFFT). Optimum parameters that give the best trade-off between performance and cost in terms of bit precision are determined. It was found that these parameters depend on the modulation format as well as the size of the FFT used in the system. The thesis then presents the design of a multi-gigabit real-time O-OFDM transmitter based on field programmable gate array (FPGA) implementation. The 21.4 GS/s real-time transmitter was built and used to transmit 8.36 Gb/s directly-detected single sideband QPSK-OFDM signals over 1600 km of uncompensated standard single mode fibre. This was one of the first demonstrations of real-time OFDM transmitters operating at such high line rates. It remains the longest transmission distance achieved with a real-time OFDM transmitter. The next step in confirming the feasibility of O-OFDM involves the design and assessment of application-specific integrated circuit (ASIC) implementations. In the final part of the thesis, digital signal processing (DSP) circuits for 21.8 Gb/s and 43.7 Gb/s QPSK- and 16-QAM-encoded O-OFDM transceivers with 50 data subcarriers were designed at the register-transfer-level, and synthesis and simulations were carried out to assess their performance, power consumption, and chip area. The aim of the study is to determine the suitability of OFDM technology for low-cost optical interconnects. Power calculations based on synthesis for a 65nm standard-cell library show that the DSP components of the transceiver consume 18.2 mW/Gb/s and 12.8 mW/Gb/s in the case of QPSK and 16-QAM respectively. The effects of modulation format and FFT size on the area and power consumption of the transceivers are also quantified. Finally, characterisation results showing the trade-offs between energy consumption and chip footprint are presented and analysed to help designers optimise the transceivers according the requirements and specifications.
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Gao, Ruixin. "Optical packet networking using optical time division multiplexing." Thesis, Sheffield Hallam University, 2003. http://shura.shu.ac.uk/19219/.
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Growing demands for capacity have stimulated the development of high-speed optical shared media networks. At present, most research on optical networking has concentrated on wavelength-division multiplexing (WDM). Optical time-division multiplexing (OTDM), which offers advantages over WDM networks, is considered as an alternative to WDM for future networks proving a single stream data rates of 100 Gb/s using a single wavelength. In such systems all optical routers, which overcome the bottleneck of optoelectronic conversion, play an important role. This thesis concentrates on the modelling and simulation of a novel optical router, which uses two terahertz optical asymmetric demultiplexers (TOAD) as the routing element for OTDM systems. In this work, the author has developed a mathematical model of an all optical router based on TOADs. The model architecture is based on a system, which has as its input an OTDM packet containing header and payload information. The model simulates extraction of header information, using one TOAD, from the data stream, which is subsequently used to make a routing decision. The payload information is routed through a second TOAD according to the information contained in the header. A comprehensive theoretical analysis supported by computer simulations has been carried out to study characteristics of crosstalk, noises, signal to noise ratio (SNR), Bit error rate (BER), and power penalty of the router. The results obtained, whenever possible, have been compared with the experimented data. The performance analysis of the all optical router is shown by the simulation results. The proposed router is capable of routing packet containing data in excess of 250 Gb/s all in optical domain. New models of all optical router with multi-input and outputs have been developed i.e. 1x4 router, 2x2 router, which are based on 1x2 TOAD routers. Results show that threshold switching energy is present at 0.2 pJ. Higher values result in a decrease in crosstalk and lower values result in negligible switching. Also shown is crosstalk induced penalty depends on the crosstalk level of individual 1x2 switches as well as on the size and architecture of the switching fabric. Finally, it has been shown that the proposed all-optical router has potentially useful characteristics as a component for high-speed optical TDM networks due to its ultrafast switching capability compared with existing devices. At this stage a simple 8 by 8 Banyan network is presented, however further work will enhance the model to a network with more inputs and outputs.
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Schwartz, Paul D., and Christopher B. Hersman. "A HIGH SPEED REAL TIME SPACE QUALIFIED TIME DIVISION MULTIPLEXED DATA FORMATTER." International Foundation for Telemetering, 1994. http://hdl.handle.net/10150/608564.
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International Telemetering Conference Proceedings / October 17-20, 1994 / Town & Country Hotel and Conference Center, San Diego, California<br>A system to generate a contiguous high speed time division multiplexed (TDM)
spacecraft downlink data stream has been developed. The 25 MBPS downlink data
stream contains high rate real time imager data, intermediate rate subsystem processor
data, and low rate spacecraft housekeeping data. Imager data is transferred directly
into the appropriate TDM downlink data window using control signals and clocks
generated in the central data formatter and distributed to the data sources. Cable and
electronics delays inherent in this process can amount to several clock periods, while
the uncertainty and variations in those delays (e.g. temperature effects) can exceed the
clock period. Unique (patent pending) electronic circuitry has been included in the
data formatter to sense the total data gathering delay for each high speed data source
and use the results to control series programmable delay elements to equalize the
delays from all sources and permit the formation of a contiguous output data stream.
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OLIVIERI, BRUNO SAPHA. "INTERROGATION SYSTEM OF FIBER BRAGG GRATING SENSORS USING TIME DIVISION MULTIPLEXING AND WAVELENGTH DIVISION MULTIPLEXING." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=5905@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR<br>Um sistema de interrogação de sensores a rede de Bragg
utilizando multiplexação no tempo e multiplexação no
comprimento de onda é proposto e demonstrado. O sistema
apresenta uma solução para a medição de grandezas
associadas ao espectro de reflexão de redes de Bragg,
possibilitando o aumento do número de sensores a rede de
Bragg monitorados através de grandes distâncias em uma
mesma fibra óptica, sem um aumento significativo dos
custos. O aspecto inovador deste sistema reside na
particular associação das seguintes características: o uso
de fonte pulsada de banda larga, a disposição, em série, de
um grande número de sensores a rede de Bragg de baixa
refletividade, a técnica de reutilização dos mesmos
comprimentos de onda nominais em grupos contendo vários
sensores com comprimentos de onda nominais distintos e um
processo de filtragem espectral e análise de sinais
pulsados utilizando o filtro DWDM comercial. Aspectos
teóricos e experimentais considerando os princípios de
trabalho desta técnica são discutidos. Comparações entre
resultados simulados e experimentais do sistema implantado
mostram boa concordância. Resultados experimentais apontam
uma faixa dinâmica de 1,7 nm, podendo encontrar aplicações
em medição de temperatura com uma faixa de 150°C.
Incertezas com valores médios abaixo de 20 picometros foram
obtidas. Simulações experimentais apontam a possibilidade
de utilização de um número de aproximadamente 70 sensores
com 0,4% de refletividade, por comprimento de onda.
Considerando a largura de banda do dispositivo DWDM (1539-
1565 nm) utilizado neste sistema, e um espaçamento de 7 nm
por comprimento de onda nominal de sensor, extrapolações
mostram que este número pode chegar a 210 sensores em três
diferentes comprimentos de onda nominais de sensor.
Considerando as bandas C e L este número pode chegar a
aproximadamente 1000 sensores em 14 diferentes comprimentos
de onda nominais de sensor.<br>An interrogation system of fiber Bragg grating sensors
using time division multiplexing and wavelength division
multiplexing is proposed and demonstrated. The system
presents a solution to measure the magnitudes associated to
the reflection spectrum of the fiber Bragg gratings, making
possible to increase the number of the Bragg gratings
sensors monitored through large distances at the same fiber
optic, without a great increase in the costs. The
innovative aspect of this system is the particular
association of the following characteristics: the use of a
pulsed broad band source, the disposition, in series, of a
large number of low reflectivity Bragg gratings sensors,
the reusing technique of the same nominal wavelengths in
groups containing several numbers of sensors with distinct
nominal wavelengths, and a spectral analyzing and filtering
process of pulsed signals using a commercial DWDM filter.
Theoretical and experimental aspects regarding the working
principles of this technique are discussed. Comparisons
between experimental and simulated results show a good
agreement. Experimental results indicate that a dynamic
range of 1,7 nm was obtained. It can be used in temperature
measurement systems, with a 150°C range. Uncertainties
equivalent to approximately 20 picometers was obtained.
Experimental simulations indicate that it would be possible
to use a number of approximately 70 sensors with 0,4%
reflectivity at each nominal sensor wavelength. Considering
the DWDM filter bandwidth (1539-1565 nm) used in this
system, and a spectral separation of 7 nm by nominal sensor
wavelength, extrapolations indicate that a number of 210
sensors can be obtained, in three different nominal sensor
wavelength. Using the C-band and the L-band, a number of
1000 sensors can be obtained, in fourteen different nominal
sensor wavelength.
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Lam, W.-H. "Wideband time-division and spread-spectrum multiple access methods." Thesis, University of Southampton, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383353.
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Lockey, R. A. "Optoelectronic time-division multiplexing for multicomponent laser doppler anemometry." Thesis, Cranfield University, 1996. http://dspace.lib.cranfield.ac.uk/handle/1826/11052.
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This thesis describes the investigation of time-division multiplexing for use in
mUlticomponent laser Doppler anemometry (LDA). To make two- or three-
dimensional velocity measurements of a flow, two or three separate velocity
measurements in different, non-collinear or non-coplanar directions respectively must
be taken from which the flow vector can be calculated. It is necessary to separate each
velocity channel. Conventionally, the separation is carried out by optical techniques,
such as separating the signal from each channel by wavelength or polarisation, with
one detector per channel. In time division multiplexing, each channel is switched On
and off in turn. A single detector records a stream of interleaved pulses, and each
channel is extracted by taking every other or every third pulse. The envelope of the
amplitudes of the pulses varies at the Doppler frequency.
A novel system has been demonstrated which uses a single laser diode source and a
single detector. The distribution of the pulses to each channel and the delay between
each channel is carried out using a optical fibre network with fibre delay lines, with a
consequent reduction in 'electronic complexity. The characteristics of the
optoelectronic components used in the system are tested, and two signal processing
schemes are investigated. A two-dimensional Doppler difference fibre-linked probe
was constructed to demonstrate the technique.
Hybrid instruments using two Doppler difference channels and a reference beam
channel to measure orthogonal velocity components offer the possibility of avoiding
the errors introduced by non-orthogonal systems. A pulsed-diode reference beam
anemometer based on optical fibres and suitable for inclusion in a time-division
multiplexed hybrid instrument was tested.
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Parent, Marc-Antoine. "Third generation mobile communications : capacity of a time-division duplex code-division multiple access cellular system." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29543.
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This thesis describes the work done in evaluating the capacity of a multi-service third generation (3G) wireless communication system based on the Universal Mobile Telecommunication System (UNITS). More specifically, the study presented in these pages examines the Time Division Duplex (TDD) paradigm supported by the 3G Partnership Project (3GPP).<br>The goal is to establish the probability that a new connection attempt be successful as a function of the instantaneous load on the network. The sought capacity is evaluated with the help of an analytical model and a simulation tool. Both tools used a so-called system-level approach. The model and the simulator were developed based on 3GPP's standard and available data from link-level simulations.<br>Some of the significant results presented are: (1) A maximum of around 7 to 9 orthogonal codes can be used per timeslot. (2) A UMTS TDD CDMA system should be used in pico- and micro-cellular environments in order to support efficient data transmissions. (3) The multicode interference is often wrongfully neglected in capacity studies. (4) Capacity is downlink interference-limited, even with a modest MUD efficiency.
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Nisar, Hiral (Hiral Dhiraj), and Joshua Rosenzweig. "Real-time order acceptance in transportation under uncertainty." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92119.
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Thesis: M. Eng. in Logistics, Massachusetts Institute of Technology, Engineering Systems Division, 2014.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (page 56).<br>Without using any order acceptance criteria, retail companies distributing products with private transportation fleets are not able to maximize their profits because they are not adequately utilizing their capacity. The objective of this paper was to create and validate a model to determine if historical demand data can be used by retail firms operating private fleets to make effective real-time order acceptance/rejection decisions with the purpose of eliminating unprofitable orders in a short-haul transportation setting. A Java tool was generated to instantaneously decide whether or not to accept an order depending on the order location and time of receipt. The model was tested against optimal decisions using total demand knowledge and several alternative real-time decision-making strategies. The model was found to significantly outperform the alternative real-time decision making strategies and provided profits approximately eight percent lower than the optimal decisions. We conclude that using historical demand probabilities is useful in informing the decisions of retail firms seeking to utilize private fleets efficiently and increase profitability through cost reduction.<br>by Hiral Nisar and Joshua Rosenzweig.<br>M. Eng. in Logistics
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Jagatheesan, Jay, and Ryan Kilcullen. "Incorporating cycle time uncertainty to improve railcar fleet sizing." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68824.
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Thesis (M. Eng. in Logistics)--Massachusetts Institute of Technology, Engineering Systems Division, 2011.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 78-79).<br>This thesis involves railcar fleet sizing strategies with a specific company in the chemical industry. We note that the identity of the company in this report has been disguised, and some portions of the fleets have been omitted to mask their actual sizes. However, all analysis in this thesis was conducted on actual data. In our research, we evaluate the appropriateness of both deterministic and stochastic fleet sizing models for this company. In addition, we propose an economic model that is adapted from a basic inventory management policy that can be applied to fleet sizing in order to arrive at a cost-driven solution. Through our research, we demonstrate that the fleet sizing strategy of this company can be improved by incorporating transit time variability into the fleet sizing model. Additionally, we show that fleet sizes can be reduced by accurately characterizing the distributions of the underlying transit and customer holding time data. Finally, we show the potential value of considering economic factors to arrive at a fleet sizing decision that balances the cost of over-capacity with the cost of an insufficient supply of railcars.<br>by Jay Jagatheesan and Ryan Kilcullen.<br>M.Eng.in Logistics
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Caldwell, Erik R. (Erik Russell), and Bryan C. Fisher. "The impact of lead time on truckload transportation rates." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45252.
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Thesis (M. Eng. in Logistics)--Massachusetts Institute of Technology, Engineering Systems Division, 2008.<br>Includes bibliographical references (leaves 80-81).<br>The objective of this thesis was to analyze truckload shipment transactions in order to determine if rates are impacted by tender lead time, which is the amount of time between when a carrier is offered a load to when the load needs to be picked up. The research specifically focused on how tender rejections by carriers are the ultimate driver of transportation cost variances since most rates are contractually fixed in advance. The data revealed a strong correlation between tender rejections and increased costs. Many factors affect transportation costs. The transportation model in the paper included three key baseline factors: distance, origin, and destination of the load. The model also included tender and pick up day of week activity, economies of scale, carrier size, and tender lead time to quantify how the factors influence the cost of a load. The research suggests that even though the baseline factors dominate the cost of most loads, shippers can create savings by modifying business policy with regard to tender lead time and other factors included in the model.<br>by Erik R. Caldwell and Bryan C. Fisher.<br>M.Eng.in Logistics
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Cheung, Chin Ying. "Noise and crosstalk analysis of all-optical time division demultiplexers." Thesis, Sheffield Hallam University, 2001. http://shura.shu.ac.uk/19455/.
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Bandwidth limitation of conventional electrical demultiplexer restricts the data capacity of long-haul optical time division multiplexing (OTDM) systems. It is desirable to demultiplex the OTDM signal in optical domain, thereby lifting the bandwidth limitation of the electrical demultiplexer. The general principle of all-optical time division demultiplexing is to effect asymmetric changes to the optical properties of the target and non-target channels. The different optical properties of the target and non-target channels facilitate the separation of the target channel(s) from the aggregate OTDM signal. The change of optical properties of the OTDM signal can be achieved by exploiting various types of nonlinear optics effects, such as cross-phase modulation and four-wave mixing. Although the technical viability of all-optical demultiplexing has been successfully demonstrated in laboratories, there is still a lack of understanding regarding the noise and crosstalk characteristics of all-optical demultiplexers. This PhD study attempts to investigate noise and crosstalk performance of two types of all-optical time division demultiplexers, namely nonlinear optical loop mirror (NOLM) and terahertz optical asymmetric demultiplexer (TOAD). In order to evaluate the noise and crosstalk performance of NOLM and TOAD demultiplexers, mathematical models are developed to simulate the transmission window for demultiplexing the target channel. The shape of the transmission window is dependent on the device parameters of the demultiplexers. Varying input parameters of the mathematical models can simulate the effects of changing device parameters on the transmission window. Nevertheless, it is onerous to calculate transmission windows for infinite combinations of device parameters. To simplify the noise and crosstalk analysis, device parameters of NOLM and TOAD demultiplexers are optimised for maximising the peak of the transmission windows. Noise and crosstalk models are also developed forNOLM and TOAD demultiplexers. The optimised device parameters of NOLM and TOAD demultiplexers are fed into the noise and crosstalk models for analysis. Simulation results show that a tradeoff between noise and crosstalk exists for the two types of demultiplexers. Device parameters can be optimised to minimise either noise or crosstalk, but not both. Finally, the noise and crosstalk models are connected to a receiver model, where the bit-error-rate (BER) performance of OTDM systems is evaluated. The BER performances of the NOLM and TOAD demultiplexing are compared using the optimised device parameters. It is found that TOAD has a slightly better BER performance compared with NOLM for lower baseband bit rate (i.e. a larger number of OTDM channels for an aggregate bit rate).
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Glekas, D. "Time division multiplexing on a star coupled fibre optic network." Thesis, University of Kent, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375965.
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Cheung, Joseph Chung Shing. "Adaptive equalisers for wideband time division multiple access mobile radio." Thesis, University of Southampton, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315319.
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Lu, Chun, Yihong Yan, and Jian Song. "An Application of Sync Time Division Multiplexing in Telemetry System." International Foundation for Telemetering, 2013. http://hdl.handle.net/10150/579685.
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ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NV<br>High speed real-time data transportation is most important for telemetry systems, especially for large-scale distributed systems. This paper introduces a STDM (Sync Time Division Multiplexing) network structure for data transportation between devices in telemetry systems. The data in these systems is transported through virtual channels between devices. In addition, a proper frame format is designed based on PCM format to meet the needs of synchronization and real-time transportation in large-scale distributed telemetry systems.
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Wanfang, Zhang. "THE TIME DIVISION MULTIPLEX MEASURING SYSTEM FOR SINGLE-TRANSIENT SIGNALS." International Foundation for Telemetering, 1993. http://hdl.handle.net/10150/608868.
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International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, Nevada<br>In order to reduce the measuring channels for the single-transient signals, the author
propose the time division multiplex technique and introduce the method of SAW delay
line in this paper.
That used method of SAW tap-delay line in this system is different from previous
methods consists in making traditional method, which is one-path signal input
different delayed multi- path signals output, alter new method, which is simultaneous
multi-path signal inputs that are respectively delayed and one-path signal serial output.
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Buot, Theodore V. "Reservation-time division multiple access protocols for wireless personal communications /." Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09phb944.pdf.
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Walkenhorst, Joseph Sean. "Quantifying the value of reduced lead time and increased delivery frequency." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40355.
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Thesis (M. Eng. in Logistics)--Massachusetts Institute of Technology, Engineering Systems Division, 2007.<br>Includes bibliographical references (leaf 63).<br>A large consumer package goods company would like to know the answer to the following question. What is the value to its customers of increased delivery frequency or reduced lead time? To answer this question, we collected shipment and inventory data for three customers: a mass merchandiser, a grocery store chain, and a drug store chain in the US. We examined the shipment histories to the customers' Distribution Centers (DCs) in the West, the Midwest, and the East for SKUs from three product families. We developed a continuous review QR inventory model to calculate the theoretical inventories for these high volume SKUs. We used this model to assess the theoretical inventory requirements for multiple scenarios entailing some form of increased frequency or decreased lead time. Some companies run heavy promotions during which time the majority of sales occur. If such a company is to benefit from reduced lead time from its supplier to their DCs, shipments from their DCs to stores must be frequent enough to respond to their stores' needs during a promotion.<br>(cont.) If this is not the case, the main opportunity to reduce inventory will be through better promotional planning. The data showed that there was a great amount of variability in the average inventory levels at the customers' DCs, which suggested that some DCs have large excesses of inventory for some SKUs. If customers could simply match their best in class inventory levels across all other products and locations, possibly $120 million could be saved annually in inventory carrying costs across all of this company's customers. The model also suggested that increasing delivery frequency provides a greater value than decreasing lead time. The methodology used to calculate the value of potential savings to customers could be applied to other locations or other industries.<br>by Joseph Sean Walkenhorst.<br>M.Eng.in Logistics
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Macedo, Aleandro Soares. "Antenna sector-time division multiple access system for indoor wireless communications." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0014/NQ35234.pdf.
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Robinson, Bryan S. (Bryan Shawn) 1975. "Semiconductor-based all-optical switching for optical time-division multiplexed networks." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/17590.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.<br>Includes bibliographical references.<br>All-optical switching will likely be required for future optical networks operating at data rates which exceed electronic processing speeds. Switches utilizing nonlinearities in semiconductor optical amplifiers (SOA) are particularly attractive due to their compact size, low required switching energies, and high potential for integration. In this dissertation we investigate the practical application of such semiconductor-based all-optical switches in next-generation optical networks. We present both theoretical and experimental studies of SOA-based interferometric switches. A detailed numerical model for the dynamic response of an SOA to an intensity-modulated optical signal is described. The model is validated using novel pump-probe techniques to measure the time-domain response of an SOA subject to various levels of saturation. The model is then used to evaluate the performance of three common SOA-based interferometric all-optical switches. The use of SOAs in optical transmission systems has been limited due to the deleterious effects of pattern-dependent gain saturation. We develop a statistical model to study the system impact of variations of the SOA optical gain in response to a random intensity-modulated optical signal. We propose the use of pulse-position modulation (PPM) as a means for mitigating gain saturation effects in SOA-based optical processors. We present techniques for modulation and detection of optical PPM signals at data rates in excess of 100 Gbit/s. We demonstrate demultiplexing, wavelength conversion, and format conversion of optical PPM signals at data rates as high as 80 Gbit/s. Finally, we report on experimental demonstrations of an optical interface for slotted OTDM networks.<br>(cont.) We implement head-end and transmitter nodes capable of producing fully loaded optical slots at an aggregate network data rate of 112.5 Gbit/s. We demonstrate a fully functional receiver node which utilizes semiconductor-based all-optical logic for synchronization, address processing, and rate conversion.<br>by Bryan S. Robinson.<br>Ph.D.
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Paulson, Donald H. "Analysis of a proposed third generation (3G) mobile communication standard, time division-synchronous code division multiple access (TD-SCDMA)." Thesis, Monterey, California. Naval Postgraduate School, 2002. http://hdl.handle.net/10945/5860.
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Approved for public release; distribution is unlimited<br>With a growing number of consumers utilizing the Internet, companies have foreseen a consumer demand for high-speed wireless access. Since current mobile cellular systems can transfer at most 115.2 kbps per user, a third generation of mobile cellular service has been under development by various organizations since 1997. This new generation of technology will support data rates up to 2 Mbps for stationary mobiles and up to 144 kbps for vehicular traffic. This thesis focuses mainly on TD-SCDMA, one of many candidates submitted to the International Telecommunications Union for third generation review. The standard, developed in China by the Chinese Academy of Telecommunications Technology, employs both code-division multiple access and time-division duplexing to support both forward and reverse transmissions on one physical layer. This aspect, along with other common features of TD-SCDMA, will be studied and evaluated to determine if this new technology is a viable option for future commercial or military deployment.
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Reifel, Denise. "A comparison of division I and division II student-athletes' backgrounds, time demands and perceptions of academics and athletics /." View online, 1993. http://repository.eiu.edu/theses/docs/32211998881486.pdf.
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Paulson, Donald H. "Analysis of a proposed third generation (3G) mobile communication standard, time division-synchronous code division mulitple access (TD-SCDMA)." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Jun%5FPaulson.pdf.
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McNichols, Sean T. "Reducing intraday patient wait times through just-in-time bed assignment." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99014.
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Thesis: M.B.A., Massachusetts Institute of Technology, Sloan School of Management, 2015. In conjunction with the Leaders for Global Operations Program at MIT.<br>Thesis: S.M., Massachusetts Institute of Technology, Engineering Systems Division, 2015. In conjunction with the Leaders for Global Operations Program at MIT.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 120-121).<br>Massachusetts General Hospital (MGH) is the oldest and largest hospital in New England as well as the original and largest teaching hospital of the Harvard Medical School. The neuroscience units experience patient flow issues similar to those observed throughout MGH, including high bed utilization and long intraday patient wait times. This project focuses on the neuroscience units as a microcosm of the hospital. MGH consistently operates near capacity. Patients from the emergency department, the perioperative environment, intensive care units (ICUs) and other sources compete for beds. The admitting department manages the bed assignment process across MGH. Assignments are often made without access to all relevant information, such as expected admission, surgery and discharge timing. As a result of common procedures, patients are frequently assigned to a bed before they are clinically ready to move. Our analysis reveals that suboptimal bed assignment and patient transfer processes are among the leading root causes of intraday patient delays. The primary objective of the project is to develop a bed assignment policy to reduce intraday patient wait times. The policy consists of a bed assignment algorithm and enabling bed management processes. To account for patient acuity, the algorithm segments patients by movement (e.g., ED-to-ICU). The target maximum wait for each segment is the acceptable wait length (AWL). The algorithm ranks patients based on their ready times and the AWLs, and assigns beds primarily on a just-in-time (JIT) basis. The enabling bed management processes include small-scale early discharge and early transfer interventions to better align the intraday timing of demand for inpatient beds with available capacity. A simulation of neuroscience patient flow is used to evaluate different approaches. The model shows that adoption of the JIT policy would increase the percentage of patients who experience bed waits within the AWL for all movement types. Predicted bed waits for patients who require ICU-level care would be 30 minutes or less for 90% of ED patients and 95% of OR patients (improvements from historical baselines of 44% and 91%, respectively). Predicted bed waits for transfers to floor beds would be two hours or less for 81% of ED patients and 93% of OR patients (improvements from historical baselines of 63% and 84%, respectively). The solution significantly reduces intraday patient wait times without a major increase in hospital capacity.<br>by Sean T. McNichols.<br>M.B.A.<br>S.M.
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Baker, Dirk A. "Space-time block coding with imperfect channel estimates." Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=1843.
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Thesis (M.S.)--West Virginia University, 2001.<br>Title from document title page. Document formatted into pages; contains iv, 74 p. : ill. Includes abstract. Includes bibliographical references (p. 73-74).
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Sudarsanam, Nandan 1981. "Ensembles of Adaptive One-Factor at-a-Time experiments : methods, evaluation, and theory." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/53211.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Engineering Systems Division, 2008.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 81-86).<br>This thesis recommends an experimentation methodology which can be used to improve systems, processes and products. The proposed technique borrows insights from statistical prediction practices referred to as Ensemble Methods, to extend Adaptive One-Factor-at-a-Time (aOFAT) experimentation. The algorithm is developed for an input space where each variable assumes two or more discrete levels. Ensemble methods are common data mining procedures in which a set of similar predictors is created and the overall prediction is achieved through the aggregation of these units. In a methodologically similar way this study proposes to plan and execute multiple aOFAT experiments on the same system with minor differences in experimental setup, such as starting points, or order of variable changes. Experimental conclusions are arrived at by aggregating the multiple, individual aOFATs. Different strategies for selecting starting points, order of variable changes, and aggregation techniques are explored. The proposed algorithm is compared to the performance of a traditional form of experimentation, namely a single orthogonal array (full and fractional factorial designs), which is equally resource intensive. Comparisons between the two experimental algorithms are conducted using a hierarchical probability meta-model (HPM) and an illustrative case study. The case is a wet clutch system with the goal of minimizing drag torque. Across both studies (HPM and case study), it is found that the proposed procedure is superior in performance to the traditional method.<br>(cont.) This is consistent across various levels of experimental error, comparisons at different resource intensities, and through a wide array of response surfaces generated by the meta-model. At best, the proposed algorithm provides an expected value of improvement that is 15% higher than the traditional approach, at worst, the two methods are equally effective, and on average the improvement is about 10% higher. These findings suggest that the ensemble of aOFATs can be an effective and often preferred alternative to the use of orthogonal arrays for experimentation. This thesis also shows that it more effective to apply ensemble procedures to aOFAT versus applying ensemble techniques on multiple, highly-fractioned orthogonal designs (each being as resource intensive as a single aOFAT). A theoretical discussion explaining the reasons for the superior performance of the proposed algorithm supports the empirical findings.<br>by Nandan Sudarsanam.<br>Ph.D.
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Lindström, Magnus. "Resource allocation for asymmetric traffic in time division duplexing mode cellular networks." Licentiate thesis, KTH, Signals, Sensors and Systems, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1576.
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<p>Time Division Duplexing (TDD) mode systems provide greatflexibility that can be used to implement asymmetrical links.Adverse interference conditions easily arise, however.Especially if dicerent asymmetries are required in neighbouringcells.</p><p>This thesis examines the feasibility of supportingasymmetric links in a locally centralised system in a Manhattanenvironment. Methods to avoid inter-mobile and inter-basestation interference are studied and possible performance gainsare assessed. Further, the implications of having differentasymmetries in neighbouring cells and the importance of thebase station placement are investigated.</p><p>The thesis shows that asymmetric traffic can be provided inTDD mode systems with a locally centralised resource allocationscheme. Capacity is increased noticeably when compared to asystem with a fixed global asymmetry. Careful handling ofinter-mobile station interference is of great importancethough, to keep outage reasonably low. Measuring link-gainsbetween mobile stations is considered infeasible. However, itis shown that outage can be reduced significantly by using somesimple allocation rules and link-gain estimates proposed andevaluated in the thesis. Results also show that it is possibleto have different asymmetry ratios in different parts of thesystem, though large asymmetry differences between neighbouringcells will adversely affect capacity. Where base stations areplaced is important for system capacity, but as long as thebase stations are not placed in the intersections, the exactlocations are not critical.</p>
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GETANEH, WORKALEMAHU AGEREKIBRE. "Optical Time Domain Reflectometer based Wavelength Division Multiplexing Passive Optical Network Monitoring." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-105149.
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This project focuses on wavelength division multiplexing passive optical network (WDM-PON) supervision using optical time domain reflectometer (OTDR) for detection and localization of any fault occurred in optical distribution network. The objective is to investigate the impact of OTDR monitoring signal on the data transmission in the WDM-PON based on wavelength re-use system, where the same wavelength is assigned for both upstream and downstream to each end user. Experimental validation has been carried out to measure three different schemes, i.e. back-to-back, WDM-PON with and without OTDR connection by using 1xN and NxN arrayed waveguide gratings. Furthermore, a comprehensive comparison has been made to trace out the effect of the monitoring signal which is transmitted together with the data through the implemented setup. Finally, the result has confirmed that the OTDR supervision signal does not affect the data transmission. The experiment has been carried out at Ericsson AB, Kista.
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Cooper, David J. F. "Time division multiplexing of a serial fibre optic Bragg grating sensor array." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0001/MQ45424.pdf.
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Hoover, Daniel R. Jr. "A Balancing Act: Division III Student-Athletes Time Demands and Life Roles." W&M ScholarWorks, 2012. https://scholarworks.wm.edu/etd/1539618271.
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A majority of the research on student-athletes occurs at the Division I level, acid less is known about Division III student-athletes. The scant research addressing the experiences of Division III students-athletes focused on academics, campus involvement, development, and athletic identity (Griffith & Johnson, 2002; Heuser & Gray, 2009; Richards & Aries, 1993; Schroeder, 2000; Umbach, Palmer, Kuh, & Hannah, 2006). What remains unknown is how they manage life roles as Division III student-athletes.;This case study sought to address the time demands and life roles (e.g. athletics, family, friendship, religion, academic, and romantic interests) of student-athletes. Two private, Division Ill institutions in the Midwest were selected. A total of 21 student-athletes from both men and women's basketball teams were interviewed. The findings suggest student-athletes are strained by time demands, yet have developed strategies to better manage their time. Family serves as a foundation and the most important life role for a majority of student-athletes. Teammates, coaches, and athletic involvement offer additional support as student-athletes transition through college. The life roles of religion and romantic relationships, however, were not seen as important for student-athletes. This research concluded that Division III student-athletes juggle multiple roles but their priorities change over time. of note, participant's integrated roles over time and particular transition phases existed for students. Moreover, instead of border keepers vying to reinforce borders between roles, this study concluded that border bridgers existed instead that sought to aid students in blurring boundaries between their various roles. Male athletes were less able to describe how they managed time, whereas female athletes readily identified organizational strategies and stronger team bonds.
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Sole, Christopher J., Ashley A. Kavanaugh, William A. Sands, Jacob P. Reed, and Michael H. Stone. "Time-Series Analysis of Injury Occurrence in NCAA Division I Women’s Volleyball." Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etsu-works/4558.
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Schlesinger, Adam Ian. "Mitigating container security risk using real-time monitoring with active Radio Frequency Identification and sensors." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33353.
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Thesis (M. Eng. in Logistics)--Massachusetts Institute of Technology, Engineering Systems Division, 2005.<br>Includes bibliographical references (leaves 57-60).<br>The global village in which we live enables increased trade and commerce across regions but also brings a complicated new set of challenges such as terrorist activity, human and drug smuggling and theft in foreign or domestic locations. Containers travel the globe, across all seven continents. In the wake of intensified security concerns since the September 11, 2001 attacks, tracking containers and their contents presents an increasing concern for those institutions and personnel charged with ensuring their security. This thesis analyzes the risks associated with global container transport. The concept of an e-container is set forth as a risk mitigation technology that uses real-time monitoring of a container's physical status acquired from an array of embedded RFID-enabled sensors. A framework is suggested that relates sensor-identified signatures and phenomena to behaviors representing breaches in container security. A theoretical model suggests which sensors are required to identify the individual breaches in order to mitigate container security risk.<br>y Adam Ian Schlesinger.<br>M.Eng.in Logistics
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Blogh, Jonathan S. "Adaptive modulation and adaptive antenna assisted wireless TDMA/CDMA networks." Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341647.
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Thomson, Ty M. (Ty Matthew). "Models and analysis of yeast mating response : tools for model building, from documentation to time-dependent stimulation." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45206.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Biological Engineering Division, 2008.<br>Includes bibliographical references (p. 309-336).<br>Molecular signaling systems allow cells to sense and respond to environmental stimuli. Quantitative modeling can be a valuable tool for evaluating and extending our understanding of signaling systems. In particular, studies of the mating pheromone response system in yeast (Saccharomyces cerevisiae) have revealed many protein families and regulatory motifs also found in higher eukaryotes. This thesis develops several computational and experimental approaches that facilitate characterization of cellular signaling systems, and tests these approaches using yeast mating response as a model. Limitations in the current approach to building models of molecular systems were addressed first. For example, published computational models are often difficult to evaluate and extend because researchers rarely make available the information and assumptions generated throughout model building. I developed tools that facilitate model construction, evaluation, and extension. I used these tools to develop the YeastPheromoneModel (YPM) information repository, in which construction of an exhaustive model of the yeast mating system is documented (http://www.YeastPheromoneModel.org). Next, motivated by an ability to rapidly make many derivative models from the YPM repository and by carefully measured abundances of mating system proteins, I analyzed a model of the mating system mitogen activated protein kinase cascade. I found that varying the abundance of the scaffold protein Ste5, but not the abundances of other proteins, is expected to result in a quantitative tradeoff between total system output and dynamic range. Thus, the abundance of scaffold proteins in signaling systems may generally be under selective pressure to support specific quantitative system behavior.<br>(cont.) Finally, because traditional methods for characterizing signaling systems can be slow and tedious, I postulated that time-dependent stimulation of signaling systems might increase the richness and value of data derived from individual experiments. To do this, I devised a custom microfluidic device to expose yeast cells to pheromone in a time-dependent manner. I also developed computational approaches to investigate the use of time-dependent stimulation to characterize receptor and G protein response dynamics. I found that, at least for the receptor/G protein portion of the mating system, time-dependent stimulation does not appear to offer significant gains for constraining kinetic parameters relative to traditional step-response experiments.<br>by Ty M. Thomson.<br>Ph.D.
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Molins, Jiménez Antonio. "State-space modeling of MEG time series." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62519.
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Thesis (Ph. D. in Electrical and Medical Engineering)--Harvard-MIT Division of Health Sciences and Technology, 2010.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 121-128).<br>Magnetoencephalography (MEG) non-invasively offers information about neural activity in the brain by measuring its magnetic field. Estimating the cerebral sources of neural activity from MEG is an ill-posed inverse problem that presents several challenges. First, this inverse problem is high-dimensional, as the number of possible sources exceeds the number of MEG recording sensors by at least an order of magnitude. Second, even though the neural activity has a strong temporal dynamic and the MEG recordings are made at high-temporal resolution, the temporal dynamic is usually not exploited to enhance the spatial accuracy of the source localization. Third, whereas a dynamic form of the MEG source localization problem can be easily formulated as a state-space model (SSM) problem, the high dimension of the resulting state-space makes this approach computationally impractical. In this thesis we use a SSM to characterize from MEG recordings the spatiotemporal dynamics of underlying neural activity. We use the Kalman fixed-interval smoother (KS) to obtain maximum a posteriori (MAP) estimates of the hidden states, the expectation-maximization (EM) algorithm to obtain maximum-likelihood (ML) estimates of the parameters defining the SSM, and standard model-selection criteria to choose among competing SSMs. Because of the high dimensionality of the SSM, the computational requirements of these algorithms are high, and preclude the use of current frameworks for MEG analysis. We address these computational problems by developing an accelerated, distributed-memory version of the KS+EM algorithm appropriate for the analysis of high-dimensional data sets. Using the accelerated KS+EM algorithm, we introduce two SSM-based algorithms for MEG data analysis: KronEM (Kronecker Product modeling using KS+EM) and StimEM (Stimulus effect estimation using KS+EM). KronEM characterizes the spatiotemporal covariance of MEG recordings using an parameterization that efficiently describes the rhythmicity present in resting state neural activity. KronEM describes the data as a sum of components composed of a time-invariant spatial signature and a temporal second-order autorregresive process. In comparison with previous attempts at modeling resting-state activity, the KronEM algorithm estimates the number of such components using the data, and is able to identify an arbitrary number of them. We illustrate these properties on a simulation study, and then analyze MEG recordings collected from a human subject in resting state. The KronEM algorithm recovered components consistent with well-known physiological rhythmic activity. We then compare the resulting topographic maps of frequency with multi-taper based ones, and show that KronEM-based maps better localize naturally occurring rhythms. These results make the KronEM algorithm a useful single-trial frequency analysis technique. StimEM estimates neural activity using MEG recordings made in evoked-potential studies, in which the subject is repeatedly presented with a stimulus and only the stimulus effect is of interest. In contrast with other dynamic source-localization techniques, StimEM accepts arbitrary description of neural dynamics, parameterized as a weighted sum of user-defined candidates, and finds the MAP estimate of the weights. Using the estimated dynamics, StimEM generates a time-resolved ML estimate of the evoked-potential activity in the cortex. We illustrate the ability of StimEM to identify dynamics in a simulated data set of realistic dimensions, and show that the estimates improve substantially when dynamics are taken into account. We next analyze experimental MEG data from an auditory evoked-potential study and show that StimEM identifies dynamics consistent with neurophysiology and neuroanatomy and improves the localization of the evoked cortical response. In summary, we establish the feasibility of non-approximate SSM-based analysis of high-dimensional state-space models using a distributed-memory implementation of an accelerated KS+EM algorithm. We develop two novel algorithms to analyze MEG data in resting-state and evoked potential studies, and show that SSM analysis improves substantially on previous non-SSM based techniques.<br>by Antonio Molins Jiménez.<br>Ph.D.in Electrical and Medical Engineering
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Gross, Michael Charles. "High-rate, short-pulse sources:jitter and pedestal level in optical time-division multiplexing." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/5405.
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Ulmer, Todd G. "Resonant-cavity-enhanced surface-emitted second-harmonic generation for optical time-division demultiplexing." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/13323.
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Lee, King F. "Space-time and space-frequency coded orthogonal frequency division multiplexing transmitter diversity techniques." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/14981.
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Wong, Kar Lun (Clarence). "Space-time-frequency channel estimation for multiple-antenna orthogonal frequency division multiplexing systems." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=100244.
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We propose a linear mean square error channel estimator that exploits the joint space-time-frequency (STF) correlations of the wireless fading channel for applications in multiple-antenna orthogonal frequency division multiplexing systems. Our work generalizes existing channel estimators to the full dimensions including transmit spatial, receive spatial, time, and frequency. This allows versatile applications of our STF channel estimator to any fading environment, ranging from spatially-uncorrelated slow-varying frequency-flat channels to spatially-correlated fast-varying frequency-selective channels.<br>The proposed STF channel estimator reduces to a time-frequency (TF) channel estimator when no spatial correlations exist. In another perspective, the lower-dimension TF channel estimator can be viewed as an STF channel estimator with spatial correlation mismatch for space-time-frequency selective channels.<br>Computer simulations were performed to study the mean-square-error (MSE) behavior with different pilot parameters. We then evaluate the suitability of our STF channel estimator on a space-frequency block coded OFDM system. Bit error rate (BER) performance degradation, with respect to perfect coherent detection, is limited to less than 2 dB at a BER of 10-5 in the modified 3GPP fast-fading suburban macro environment. Modifications to the 3GPP channel involves reducing the base station angle spread to imitate a high transmit spatial correlation scenario to emphasize the benefit of exploiting spatial correlation in our STF channel estimator.
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Als, Adrian Andrew. "Mathematical modelling of all-optical buffering for ultrafast optical time division multiplexed networks." Thesis, Sheffield Hallam University, 2004. http://shura.shu.ac.uk/19258/.
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The development of a practical solution to all-optical buffer remains a challenge for high-speed (> 20 Gbit/s) optical networks. Most of the research in the field has concentrated on building test-bed solutions, however the literature review shows little evidence in the use of mathematical models to aid in the design process. This PhD study is an attempt to design and develop a mathematical model of an all-optical buffer suitable for use within optical time division multiplexed systems. The emphasis is placed on recirculating fibre loop buffers because of their inherent storage advantages. The most critical of these advantages is that the storage delay time is independent of the fibre length. While there is a precedent of employing large recirculating fibre loop architectures to simulate ultra-long haul transmission lines in research projects, their use in short length (< 500m) buffering architectures is not prevalent in the literature. This work finds a niche in this domain where the physical effects of the buffer components (e.g. optical switches) have not been previously documented. In order to optimise the bit error rate performance and characterise its dependence on the physical buffer characteristics, the buffer models are designed and simulated in MATLAB and VPI. The associated mathematical models, developed in this work, are validated by the results produced using these simulation packages. The benefit of this research is reflected in the fact that varying the parameters of the mathematical model effectively simulates the changing of physical device characteristics. Consequently, the designing process becomes less arduous, as lengthy simulation times are now reduced. Moreover, as physical implementation can now be delayed until the buffer design is optimised, production cost may be reduced.
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Kavanaugh, Ashley A., B. T. Jennings, C. D. Plourd, et al. "Relationship of Various Performance Measures over Time in NCAA Division I Volleyball Players." Digital Commons @ East Tennessee State University, 2009. https://dc.etsu.edu/etsu-works/4112.
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Morrison, Andrew. "Direction-of-arrival algorithms for space-time W-CDMA receiver structures." Thesis, University of Newcastle Upon Tyne, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341786.
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Silvennoinen, Heidi. "Essays on household time allocation decisions in a collective household model /." Helsinki : Helsinki School of Economics, 2008. http://hsepubl.lib.hse.fi/FI/diss/?cmd=show&dissid=369.
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Das, Lita. "The impact of bimodal distribution in ocean transportation transit time on logistics costs : an empirical & theoretical analysis." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/81117.
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Thesis (S.M. in Engineering Systems)--Massachusetts Institute of Technology, Engineering Systems Division, 2013.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 103-104).<br>As ocean shipments have increased alongside globalization, transit time uncertainty has increased as well. This problem was observed to have variable levels of impacts on logistics cost and safety stock levels. This thesis examines the effects of bimodality in transit time distributions -in particular, the cost of ignoring bimodality. One method common in practice is to completely ignore variability. On the other hand, a popular theoretical method to account for transit time variability is to assume that demand over transit time is normally distributed. Which is, in many cases, false. To display the incorrectness of such assumptions, the paper will compare the two approaches to empirical analysis on bimodal transit time distributions.<br>by Lita Das.<br>S.M.in Engineering Systems