Academic literature on the topic 'Urban optical network reliability'

This article analyzes the structure of the optical communication network of a small city  and  considers  the  integration  of  traditional  telephone  networks  with  new  generation  converged networks during its modernization. This allows users to meet the needs of modern telecommunications services and create highly reliable communication networks. It involves the use of PON (Passive Optical Network) technology. The structure of PON technology in different topologies has been analyzed and the reliability of the selected topology has been evaluated. 

In order to improve the timeliness of logistics distribution, based on the theory of road network smoothness and reliability, the author conducted a study on the optimization of urban logistics distribution and transportation networks based on smoothness and reliability. The concept of logistics distribution and transportation network smoothness and reliability was proposed, and a logistics distribution and transportation network optimization model was established. The solving process of ant colony algorithm was given, and finally, a comparative analysis of a case was conducted. The results showed that: With a 6% increase in total delivery distance, the reliability of the delivery network has increased by 30%. This indicates that when using the model built by the author for distribution network optimization, effective optimization of network smoothness and reliability can be achieved, while only increasing the distance by a small amount. The optimal reliability of a smooth distribution network means that the probability of delivery delays is minimized, which is the most powerful guarantee for the effective accessibility of delivery. Verified the practicality of the constructed model. The proposed logistics distribution network optimization model has practical significance in guiding decision-making for optimizing urban logistics distribution transportation networks and reducing uncertainty in the process of urban logistics distribution.

This paper discusses some results of research into reliability engineering for urban sewerage networks, and the possibility of parameter estimation for particular reliability functions so as to establish a database which will enable operational control of the network and its renovation programme. A description and classification of the network failures is proposed for the sewers and the mechanism of their effects upon the soil-water environment will be presented. Very serious consequences are indicated for parametric failures of the networks operated without any program of regular technical state supervision, in the first place without network integrity inspection. The paper aims to underpin the theoretical background for optimal coordination of the renovation process, based upon typical technologies applied nowadays.

Abstract Optimizing the design and operation of urban water distribution networks (WDNs) is a complex, nonlinear problem. The optimization of WDNs can be performed for the pumping schedule, the location and elevation of reservoirs, the physical characteristics of pipes, and the placement of pressure-reducing valves, among other objectives. This study applies the anarchic society optimization (ASO) algorithm to find the optimal location and elevation of auxiliary tanks in urban water networks. The ASO is validated with mathematical benchmark functions, and is implemented to determine the location and elevation of auxiliary tanks in two urban water networks. The fuzzy reliability index for urban water network ranges between 74 and 79%, which is close to the global optima. The ASO exhibited better performance optimizing the reliability of WDNs than the genetic algorithm.

The urban transport network involves complex processes, operating 24 h a day and 365 days a year. The sustainable development of the urban transport network using electric buses and trolleybuses that run autonomously is an urgent task since the transport network performs integral social functions and is the transport artery of any urban center. The social and economic life of a city as a whole depends on the reliability of the transportation network. A theory is proposed for the technical and economic evaluation of reliability improvement in electric buses and trolleybuses running autonomously, which enables the determination of the reliability parameters of electric buses and forecasts for the future from the point of view of optimal economic costs for the operation of electric equipment in electric buses. As a result of the application of the proposed theory, it was found that increasing the reliability of the transportation fleet can lead to a decrease in both specific operating costs and capital investments in the development of the fleet. This is achieved as a result of increasing the annual productivity of vehicles by reducing the time they are out of service to eliminate the consequences of failures and carry out maintenance and repair. The conducted experiments confirmed that the theory and methodology of optimal reliability level selection not only enable the rational use of the material resources of the urban transport network but also the release of funds for its scientific and technical development by reducing the number of failures in the electrical equipment of transport systems by 14%.

Road network traffic management and control are the key mechanisms to alleviate urban traffic congestion. With this study, we aimed to characterize the traffic flow state of urban road networks using the Macroscopic Fundamental Diagram (MFD) to support area traffic control. The core property of an MFD is that the network flow is maximized when network traffic stays at an optimal accumulation state. The property can be used to optimize the temporal and spatial distribution of traffic flow with applications such as gating control. MFD construction is the basis of these MFD-based applications. Although many studies have been conducted to construct MFDs, few studies are dedicated to improving the accuracy considering the reliability of different sources of data. To this end, we propose an MFD construction method using multi-source data based on Dempster–Shafer evidence (DS evidence) theory considering the reliability of different data sources. First, the MFD was constructed using VTD and CSD, separately. Then, the fused MFD was derived by quantifying the reliability of different sources of data for each MFD parameter based on DS evidence theory. The results under real data and simulated data show that the accuracy of the constructed MFDs was greatly improved considering the reliability of different data sources (the maximum MFD estimation error was reduced by 22.3%). The proposed method has the potential to support the evaluation of traffic operations and the optimization of signal control schemes for urban traffic networks.

The paper is devoted to the development of a methodology for reducing the cost of cable products during the construction of low-voltage networks of urban micro-districts, as well as minimizing the impact of the human factor during design. To achieve this goal, an optimization mechanism is proposed, which is based on the use of the Cartesian product of sets in combination with the gradient descent algorithm. In the optimization process, the best options for connecting consumers to substations are searched, which consider the optimal load parameters and cable line lengths. The optimal grouping of consumers be-tween substations is also studied, which ensures the effective distribution of energy re-sources. The developed approach includes automated calculation of the obtained options with their subsequent optimization according to the criteria of uniform loading of each substation and the minimum total length of low-voltage cable lines in the micro-district. This allows not only to increase the efficiency of network design, but also to ensure significant savings in material resources and time. The proposed methodology can be used to design new neighborhoods or modernize existing power supply networks, contributing to their greater reliability and cost-effectiveness.

In urban areas of developing countries, due to industrialization and population growth, water demand has been increasing significantly, thereby increasing stress on the existing water distribution systems (WDSs). Under these circumstances, maintaining equity in the allocation of water becomes a significant challenge. When building an intermittent water distribution system, it is important to provide a minimum level of supply that is acceptable as well as water supply equity. A non-dominated sorting genetic algorithm (NSGA-II) is employed for the optimal design of an intermittent water distribution network (WDN). Network resilience is taken as a measure of reliability (In), while the uniformity coefficient (CU) is taken as a measure of equity in the water supply. Maximizing network resilience, uniformity coefficient, and minimization of cost of the network are considered as the objectives in the multi-objective optimization model. Pressure-driven analysis (PDA) is used for the hydraulic simulation of the network. The NSGA-II model is applied and demonstrated over two water distribution networks taken from the literature. The results indicate that reliability and equity in WDNs can be accomplished to a reasonable extent with minimal cost.

Limited financial resources significantly impact the ability of distribution system operators to prioritize maintenance, upgrade infrastructure, and integrate advanced technologies. To optimize resource allocation, a structured and detailed analysis is essential for maximizing reliability improvements within budget constraints. This paper presents a methodology for enhancing the reliability performance of semi-urban and rural distribution networks by identifying optimal investment strategies under financial limitations. Investment options are categorized into three groups: (1) installing new components where none previously existed, (2) replacing aging, higher-failure-rate equipment with new components, and (3) upgrading both network components and operational strategies. To determine the most effective investments, the selection process aims to minimize the System Average Interruption Duration Index (SAIDI) and Energy Not Supplied (ENS), while also considering an economic metric that quantifies reliability in monetary terms. The methodology was tested on networks with diverse consumer types, incorporating Monte Carlo simulation to account for uncertainties in component reliability indices and node loads. An optimization algorithm was developed, implemented, and validated using representative test networks, demonstrating its effectiveness in guiding investment decisions for improved distribution system reliability.

In the rapidly evolving urban advanced mobility (UAM) sphere, Vehicular Ad Hoc Networks (VANETs) are crucial for robust communication and operational efficiency in future urban environments. This paper quantifies VANETs to improve their reliability and availability, essential for integrating UAM into urban infrastructures. It proposes a novel Stochastic Petri Nets (SPN) method for evaluating VANET-based Vehicle Communication and Control (VCC) architectures, crucial given the dynamic demands of UAM. The SPN model, incorporating virtual machine (VM) migration and Edge Computing, addresses VANET integration challenges with Edge Computing. It uses stochastic elements to mirror VANET scenarios, enhancing network robustness and dependability, vital for the operational integrity of UAM. Case studies using this model offer insights into system availability and reliability, guiding VANET optimizations for UAM. The paper also applies a Design of Experiments (DoE) approach for a sensitivity analysis of SPN components, identifying key parameters affecting system availability. This is critical for refining the model for UAM efficiency. This research is significant for monitoring UAM systems in future cities, presenting a cost-effective framework over traditional methods and advancing VANET reliability and availability in urban mobility contexts.

The ever increasing demands of Internet users caused by the introduction of new high bandwidth applications and online services as well as the growing number of users and devices connected to the Internet, bring many challenges for the operators, especially in the last mile section of the network. Next generation access architectures are expected to offer high sustainable bandwidth per user. They also need to support a much larger service areas to decrease number of current central offices and hence potentially save the network expenditures in the future. Obviously, it requires high capacity and low loss transmission and optical fiber technology is the only future proof candidates for broadband access. Although this technology has already been widely deployed in the core networks, it is hard to use the same expensive devices made for core segment to solve the last mile bottlenecks, due to the low number of users sharing the network resources (and deployment cost). Therefore, the next generation optical access (NGOA) networks need to be designed with consideration of cost efficiency in the first place.   Network reliability is also turning to be an important aspect for the NGOA networks as a consequence of long reach, high client count and new services requiring uninterrupted access. Consequently, new architectures not only need to be cost efficient but also they should fulfill the increasing reliability requirements.   Although several NGOA alternatives have been proposed in the literatures, there is not yet an agreement on a single architecture. As described earlier, network expenditure and reliability performance are the two main factors to be considered. Therefore, this thesis concentrates on finding a suitable alternative for future broadband access by evaluating the reliability performance and total cost of ownership for several NGOA candidates. In particular, in this thesis we analyze the tradeoff between the cost needed to deploy backup resources and the reliability performance improvement obtained by the provided survivability mechanism.   First, we identified the suitable NGOA candidates by comparing two main groups of optical access networks, namely passive optical networks (PONs) and active optical networks (AONs), in terms of cost, reliability performance and power consumption. The initial results have shown that wavelength division multiplexing PON (WDM PON) is the most promising alternative for the NGOA networks because of its high potential capacity, low cost and power consumption. So we continued our studies by investigating two WDM-based PON architectures regarding their cost and reliability performance. The study has also included a proposed fiber layout compatible with these two candidates aiming to minimize the required investment needed to offer protection. Our primary results confirmed that hybrid PON (HPON) is the best alternative for the NGOA networks. Therefore we further analyzed this candidate considering several variants of HPON. The most important components and sections of the HPON, which need to be protected to decrease the impact of each failure in the network have been identified. Based on these outcomes, two resilience architectures protecting the shared part of the HPON were proposed and their reliability performance parameters as well as cost of protection were evaluated. According to the results, using our proposed protection schemes a considerable improvement in reliability performance of the HPON variants can be provided at minor extra investment. We also introduced a cost efficient HPON architecture with different levels of protection for users with various reliability requirements, i.e. the protection of shared parts of the access network for all the connected users and end-to-end resilience scheme for some selected ones (e.g., business users). To gain an overall view on the cost efficiency of the proposed architecture, we evaluated the investment required for deploying these schemes considering several network upgrading paths towards a protected network. Moreover, a sensitivity analysis investigating the influence of network deployments time and the density of the users with higher availability requirements was presented.   In summary, we have shown that HPON is able to fulfill the main NGOA requirements such as high bandwidth per-user, large coverage and client count. The work carried out in the thesis has proved that HPON can also offer high reliability performance while keeping the network expenditures at an acceptable level. Moreover, low power consumption and high flexibility in resource allocation of this architecture, makes it a winning candidate for the NGOA networks. Therefore, HPON is a promising architecture to be deployed as NGOA network in the near future considering the fact that components are soon to be available in the market.<br><p>QC 20130530</p><br>FP7 EU project, Optical Access Seamless Evolution(OASE)

Two research topics in next-generation optical networks with wavelength-division multiplexing (WDM) technologies were investigated: (1) scalability of network management and control, and (2) resilience/reliability of networks upon faults and attacks. In scalable network management, the scalability of management information for inter-domain light-path assessment was studied. The light-path assessment was formulated as a decision problem based on decision theory and probabilistic graphical models. It was found that partial information available can provide the desired performance, i.e., a small percentage of erroneous decisions can be traded off to achieve a large saving in the amount of management information. In network resilience under malicious attacks, the resilience of all-optical networks under in-band crosstalk attacks was investigated with probabilistic graphical models. Graphical models provide an explicit view of the spatial dependencies in attack propagation, as well as computationally efficient approaches, e.g., sum-product algorithm, for studying network resilience. With the proposed cross-layer model of attack propagation, key factors that affect the resilience of the network from the physical layer and the network layer were identified. In addition, analytical results on network resilience were obtained for typical topologies including ring, star, and mesh-torus networks. In network performance upon failures, traffic-based network reliability was systematically studied. First a uniform deterministic traffic at the network layer was adopted to analyze the impacts of network topology, failure dependency, and failure protection on network reliability. Then a random network layer traffic model with Poisson arrivals was applied to further investigate the effect of network layer traffic distributions on network reliability. Finally, asymptotic results of network reliability metrics with respect to arrival rate were obtained for typical network topologies under heavy load regime. The main contributions of the thesis include: (1) fundamental understandings of scalable management and resilience of next-generation optical networks with WDM technologies; and (2) the innovative application of probabilistic graphical models, an emerging approach in machine learning, to the research of communication networks.

CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior<br>The problems of urban mobility are related, among others, the spatial distribution of activities, the significant growth of automobile use, associated with a poor public transport system, and the occurrence of negative impacts caused by load handling activities in densely populated areas. The population concentration in cities gives urban centers the role of consumption nuclei, which must be supplied continuously from streams of very different nature and origin. To estimate the reliability, risk and vulnerability associated with the route chosen from several points of origin and destination can represent change in decision making. As the cost incurred on a route to greater risk, greater variability in travel time, or more vulnerable to incidents exceed the projected cost of a route optimized by time (based on the shortest path), such a decision can be reviewed. The general objective of this study was to represent the generalized cost, incorporating the concept of vulnerability, reliability and risk of urban road network for decision making regarding the choice of route for cargo transportation. Thus, we developed a method for modeling the generalized cost that incorporates the three attributes in different supply scenarios. The experiment showed the existence of trade-off (conflicting choice)between the average time variables trip, reliability / risk and the generalized cost. Only the information of time and cost of travel are not sufficient to meet the conditions of delivery of merchandise. For the driver, holds the knowledge of the reliability or the risk of delivery of the goods can be a strategic pillar cost reduction or the medium and long-term market gains.<br>Os problemas de mobilidade urbana estÃo relacionados, dentre outros, à distribuiÃÃo espacial das atividades, ao crescimento expressivo do uso do automÃvel, associado a um sistema deficiente de transporte pÃblico, e à ocorrÃncia de impactos negativos provocados pelas atividades de movimentaÃÃo de cargas nas Ãreas adensadas. A concentraÃÃo populacional nas cidades confere aos centros urbanos papel de nÃcleos de consumo, que devem ser abastecidos continuamente a partir de fluxos de natureza e origem muito diversas. Estimar a confiabilidade, o risco e a vulnerabilidade associados à rota escolhida entre diversos pontos de origem e destino pode representar mudanÃa na tomada de decisÃo. Conforme o custo incorrido em uma rota de maior risco, maior variabilidade no tempo de viagem, ou mais vulnerÃvel à incidentes, supere o custo projetado de uma rota de otimizada pelo tempo (baseada no caminho mÃnimo), tal decisÃo pode ser reavaliada. O objetivo geral do presente trabalho fora representar o custo generalizado, incorporando o conceito da vulnerabilidade, da confiabilidade e do risco de uma rede viÃria urbana para tomada de decisÃo quanto à escolha de rota no transporte de carga. Para isso, desenvolveu-se um mÃtodo para modelagem do custo generalizado que incorpore os trÃs atributos em cenÃrios distintos de abastecimento. O experimento evidenciou a existÃncia de trade-off (escolha conflitante) entre as variÃveis de tempo mÃdio de viagem, confiabilidade/risco e o custo generalizado. Apenas as informaÃÃes de tempo e custo da viagem nÃo sÃo suficientes para suprir as condiÃÃes de entrega da mercadoria. Para o transportador, deter o conhecimento da confiabilidade, ou do risco, da entrega da mercadoria pode ser um pilar estratÃgico de reduÃÃo de custos ou de ganho de mercado à mÃdio e longo prazo.

“Connected society” where everything and everyone are connected at any time and on any location brings new challenges for the network operators. This leads to the need of upgrading the transport networks as the segment of Internet infrastructure connecting the fixed users and mobile base stations to the core/aggregation in order to provide high sustainable bandwidth, as well as supporting a massive number of connected devices. To do this, operators need to change the way that access networks are currently deployed. The future access network technologies will need to support very high capacity and very long distances, which are the inherited characteristics of optical transmission. Hence, optical fiber technology is recognized as the only future proof technology for broadband access. Capacity upgrade in the access networks can lead to a huge capacity demand in the backbone network. One promising solution to address this problem, is to keep the local traffic close to the end users as much as possible, and prevent unnecessary propagation of this type of traffic through the backbone. In this way, operators would be able to expand their access network without the significant capacity upgrade in the higher aggregation layers. Motivated by this need, a comprehensive evaluation of optical access networks is carried out in this thesis regarding ability of accommodating local traffic and amount of possible saving in the backbone by implementing locality awareness schemes. Meanwhile, next generation optical access (NGOA) networks have to provide high capacity at low cost while fulfilling the increasing reliability requirements of future services and customers. Therefore, finding cost-efficient and reliable alternative for future broadband access is one of the most important contributions of this thesis. We analyzed the tradeoff between the cost needed to deploy backup resources and the reliability performance improvement obtained by the proposed protection mechanism. Among different NGOA architectures, hybrid time and wavelength division multiplexing passive optical network (TWDM PON) is considered as a proper candidate providing high capacity and large coverage. Therefore, this approach is further analyzed and several tailored protection schemes with high flexibility are proposed to statisfy different requirements from the residential and business users in the same PON.  The work carried out in the thesis has proved that TWDM PON can also offer high reliability performance while keeping the network expenditures at an acceptable level. Considering some other advantages such as low power consumption and high flexibility in resource allocation of this architecture, it has high potential to be the best candidate for NGOA networks.  Moreover, new deployments of radio access networks supporting the increasing capacity demand of mobile users lead to the upgrade of the backhaul segment as a part of broadband access infrastructure. Hence, this thesis also contributes with a comprehensive techno-economic evaluation methodology for mobile backhaul. Several technologies are investigated in order to find the most cost-efficient solution for backhauling the high capacity mobile networks.  Finally, a PON-based mobile backhaul with high capacity and low latency has been proposed for handling coordinated multipoint transmission systems in order to achieve high quality of experience for mobile users.<br><p>QC 20150320</p>

When designing urban water systems (i.e. water distribution and sewer systems) it is imperative that uncertainty is taken into consideration. However, this is a challenging problem due to the inherent uncertainty associated with both system loading requirements and the potential for physical components failure. It is therefore desirable to improve the reliability of each system in order to account for these uncertainties. Although it is possible to directly evaluate the reliability of a water distribution systems (WDS) (using reliability measures), the calculation processes involved are computationally intensive and therefore unsuitable for some state-of-the-art, iterative design approaches (such as optimisation). Consequently, interest has recently grown in the use of reliability indicators, which are simpler and faster to evaluate than conventional direct reliability methods. In this thesis, a novel measure (the RUF) is developed to quantify reliability in urban water systems with a view to enhance their robustness under a range of future scenarios (Policy Reform, Market Forces, Fortress World and New-Sustainability Paradigm). The considered four future scenarios were synthesized in the EPSRC supported multidisciplinary 4 year project: Urban Futures. Each investigated urban future scenario is characterised by a distinct household water demand and local demand distribution (emerging due to different urban forms evolving in future scenarios). In order to assess the impact of urban futures, RUF has been incorporated into Urban Water System (UWS) dynamic simulations for both WDSs and Foul Sewer Systems (FSSs) using open source codes of EPANET and SWMM. Additionally, in order to overcome extensive computational effort, resulting from the use of traditional reliability measures, a new holistic reliability indicator, the hydraulic power entropy (IHPE) has been developed and compared to existing reliability indicators. Additionally, the relationship between the new reliability indicator and the above mentioned RUF reliability measure is investigated. Results suggest that the magnitude of the IHPE in network solutions provides a holistic indication of the hydraulic performance and reliability for a WDS. However, the performance of optimal solutions under some Urban Futures indicates that additional design interventions are required in order to achieve desired future operation. This thesis also proposes a new holistic foul sewer system (FSS) reliability indicator (the IFSR). The IFSR represents sewer performance as a function of excess pipe capacity (in terms of available increase and also decrease in inflow). The indicator has been tested for two case studies (i.e. different sewer network layouts). Results suggest that the magnitude of IFSR has positive correlations with a number of identified key performance indicators (i.e. relating to capacity, velocity, blockages). Finally, an Integrated Design Approach (IDA) has been developed in order to assess the implications of applying design interventions on both a WDS and downstream FSS. The approach holistically considers present and future operation of each interconnected system. The approach was subsequently demonstrated using two proposed design interventions. Results suggest that, for the considered design interventions, there is trade-off between the simultaneous improvement of both WDS and FSS operation and reliability.

The energy consumption of communication networks is continuously growing. Many energy saving approaches have been proposed at the device, system, and network level. The most promising way to address this problem is to utilize photonic technologies as much as possible thanks to their low energy consumption per bit performance. Moreover, several approaches have been proposed to further reduce the energy consumption in optical networks. One popular technique exploits low power modes (e.g., sleep or doze mode) for devices that are not used. However, sleep mode based approaches may affect the way optical connections (i.e., lightpaths) are routed, or alter the characteristics of some devices. This in turn may have a detrimental impact on crucial network/device performance parameters. In other words a green approach may introduce additional delay, change the level of resource utilization in the network, or even impact the lifetime of a device, resulting in increased network operational cost. This thesis provides a study that carefully assesses, in both access and core networks, the trade-off between the benefits of sleep-based energy-efficient schemes and their possible side-effects. In fiber access networks putting a device into sleep mode and waking it up can introduce a significant energy overhead. Already proposed energy-efficient approaches reduce this overhead by aggregating as much as possible the traffic before a transmission. However, aggregating data may cause an additional delay that in some cases might not be acceptable. This thesis investigates the trade-off between energy saving and additional packet delay in the case of a LTE backhaul network based on wavelength division multiplexing passive optical network (WDM-PON). The thesis proposes a novel energy-efficient approach based on the dozing concept able to precisely control when a transmitter needs to wake up in order to maximize the time spent in sleep mode, while assuring that packet transmissions are completed before a given deadline. The proposed scheme is also able to exploit possibly diverse traffic delay requirements to further improve energy saving performance. In optical core networks, one way to decrease the energy consumption is to minimize the number of used active devices by aggregating the lightpaths on the lowest possible number of active fiber links. Routing strategies based on this intuition are beneficial in terms of energy saving, but on the other hand may impact the network performance (e.g., blocking probability) by affecting length of the lightpaths and link occupancy distribution. This trade-off is evaluated in the thesis with the help of a specially designed routing and wavelength assignment (RWA) strategy referred to as weighted power aware lightpath routing (WPA-LR). The WPA-LR strategy permits the fine tuning between the minimization of two objectives: energy consumption and network resource (i.e., wavelength) utilization. Evaluation results confirm that energy efficiency and network performance are conflicting objectives. However, the proposed WPA-LR strategy offers energy minimization with acceptable impact on the network performance. The thesis also investigates the impact that sleep-based energy-efficient strategies have on the lifetime of a number of optical network devices, in both access and core networks. In fact, utilizing a sleep mode functionality may change the operational conditions of the device which can impact the device lifetime. This is a crucial aspect to consider because it may directly affect the network operational cost related to fault management. The thesis provides a methodology to assess under which conditions and for which devices an energy-efficient scheme may lead to overall cost benefit vs. a (possible) increase of reparation cost. It was found that in access networks and with business customers a small lifetime variation in optical line terminals (OLTs) or in optical network units (ONUs) can lead to significant cost increase that cannot be covered by the profits coming from the energy saving. In core networks erbium doped fiber amplifiers (EDFAs) are the most vulnerable devices in terms of impact on their lifetime. For this reason it was found that the usage of green routing algorithms based on putting EDFAs into sleep mode may not always be economically beneficial. In conclusion this thesis provides a different perspective on sleep mode based energy-efficient algorithms where the potential benefit in terms of energy saving is weighted against the impact of a possible degradation of the network performance and devices lifetime. On the other hand these performance degradations can be controlled and limited by the proposed algorithms.<br>Energikonsumtionen av kommunikationsnätverk, växer kontinuerligt. Många energibesparande åtgärder har föreslagits, såväl på komponentnivå, systemnivå och nätverksnivå. Det mest lovande sättet att hantera energibehov i kommunikationsnätverk är att utnyttja optisk teknologi så mycket som möjligt då denna har potential att ge låg energiförbrukning per bit. Det finns också ett antal föreslagna metoder för att ytterligare reducera energibehovet i optiska nätverk. En av de mest använda teknikerna bygger på att låta enheter som ej används gå ner på låg effekt (”sovläge”). Om detta används i allt för hög utsträckning kan det dock påverka hur optiska förbindelser (sk lightpaths) sätts upp eller ge förändrade egenskaper hos de aktuella komponenterna. Detta kan i sin tur ha en skadlig inverkan på de centrala nätverks- och komponentegenskaper vilket påverkar prestandan. Med andra ord kan en sådan ”grön” ansats baserad på sovläge leda till ökad fördröjning, förändring av resursutnyttjandet i nätet och till och med påverka risken för att det uppstår fel i komponenterna vilket ökar driftskostnaden för nätet. Denna avhandling fokuserar på dessa aspekter och visar upp resultat som belyser avvägningen mellan sovlägesbaserade energieffektiva strategier och deras eventuella bieffekter. Att slå av och väcka upp komponenter i optiska access-nätverk kan vara förknippat med en signifikant extra energikostnad. Tidigare föreslagna energieffektiva strategier försöker reducera denna ökade energikostnad genom att samla så mycket trafik som möjligt innan överföringen sker. Dock kan detta leda till ökad fördröjning som i vissa lägen inte är acceptabel. I avhandlingen undersöker vi avvägningen mellan energibesparingar och ökad paketfördröjning i fallet med LTE distributionsnät baserade på våglängsmultiplexerade passiva optiska nätverk (WDM-PON). Vi föreslår en ny energieffektiv ansats baserad på att enheter försätts i ”slummer-läge”. Detta gör det möjligt att med god precision bestämma när en sändare behöver väckas upp i syfte att maximera tiden i sovläget och att försäkra sig om att paketen kommer fram inom avsedd tid. Strategin är även kapabel att utnyttja differentierad fördröjning för att ytterligare förbättra energibesparingen. Ett sätt att minska energikonsumtionen i optiska distributionsnät är att minimera antalet aktiva enheter genom att exempelvis samla optiska förbindelser till ett minimalt antal aktiva fiberlänkar. Routingstrategier som utgår från denna princip är fördelaktiga ur energisynpunkt men kan å andra sidan skada nätverksprestanda (exempelvis blockeringssannolikhet) genom påverkan på förbindelselängder och annorlunda belastning av länkarna. Denna avvägning utvärderas i avhandlingen med hjälp av en specifikt utformad strategi för routing och våglängstilldelning (RWA) som vi benämner ”viktad effektmedveten optisk förbindelserouting” (WPA-LR). Denna strategi möjliggör noggrann avvägning mellan minimeringen av två kriterier: å ena sidan energikonsumtion, å andra sidan utnyttjandet av nätverksresurser (speciellt väglängdsutnyttjandet). Vår utvärdering bekräftar att energieffektivitet och nätverksprestanda står i motsatsförhållande till varandra. Dock erbjuder WPA-LR strategin minimering av energin med en acceptabel påverkan på nätverksprestanda. Slutligen undersöks i avhandlingen den påverkan som sovlägesbaserade energieffektiva strategier har på livslängden för optiska nätverkskomponenter, både i access- och i distributionsnät. Användning av sovlägesfunktion kan påverka arbetsförhållandena för en komponent, något som i sin tur kan påverka livslängden. Detta är en kritisk aspekt att ta i beaktande då det direkt kan påverka driftskostnaden kopplad till nätunderhållet. En metod ges för att utvärdera under vilka förhållanden och för vilka enheter en energieffektiv strategi kan leda till en total kostnadsfördel jämfört med en (möjlig) ökning av reparationskostnaderna. Ett resultat är att, i accessnät och för företagsanvändare, så kan även en liten variation i feluppkomst i optiska linjeterminaler (OLTs) eller optiska nätverksenheter (ONUs) leda till signifikanta kostnadsförluster vilka inte kan kompenseras genom de vinster som kan åstadkommas med energibesparingar. I distributionsnät är erbium-dopade fiberförstärkare (EDFAs) de mest utsatta enheterna vad gäller inverkan på livslängd. Genom att studera routingstrategier (ex.vis WPA-LR) har vi funnit att användningen av ”gröna” routingalgoritmer baserade på att lägga EDFAs i sovläge inte alltid är ekonomiskt fördelaktigt. Denna avhandling ger ett perspektiv på sovlägesbaserade energieffektiviseringsalgoritmer där de potentiella fördelarna vad gäller minskade driftskostnader ställs mot möjliga försämringar av nätverksprestanda och komponenters livslängd. Å andra sidan kan dessa försämringar hållas under kontroll och begränsas av den föreslagna algoritmen.<br>La consommation d'énergie des réseaux de communication ne cesse de croître. Ce problème fait l’objet de nombreuses approches orientées vers les économies d'énergie (écoénergétiques) au niveau des appareils (équipements) des systèmes et des réseaux. La façon la plus prometteuse de limiter l’augmentation de consommation évoquée est d'utiliser autant que possible des technologies photoniques, vu leur faible consommation d'énergie par bit. Plusieurs autres approches ont été proposées pour réduire davantage encore la consommation d'énergie dans des réseaux optiques. Une technique populaire exploite les modes de faible puissance (par exemple le mode veille) pour les appareils qui ne sont pas utilisés. Cependant, les approches basées sur le mode de veille peuvent affecter la manière dont les liaisons optiques (circuits optiques) sont acheminées, ou modifier les caractéristiques de certains appareils. Cela peut avoir un impact négatif sur les paramètres de performance des réseaux/équipements cruciaux. En d'autres termes, une approche écoénergétique peut introduire un retard supplémentaire, changer le niveau d'utilisation des ressources dans le réseau, ou même avoir un impact sur le taux d'échec d'un équipement, entraînant une augmentation des coûts d'exploitation du réseau. Cette thèse évalue attentivement, à la fois dans le réseau d'accès mais aussi dans le cœur du réseau, le compromis entre les avantages des régimes économes en énergie utilisant le mode veille et leurs effets secondaires possibles. Dans les réseaux d'accès optiques, mettre un équipement en mode veille et le réactiver peut introduire une surcharge d'énergie significative. Les approches d'économie d'énergie déjà proposées réduisent cette surcharge en regroupant autant que possible le trafic avant sa transmission. Toutefois, les données d'agrégation peuvent provoquer un retard supplémentaire qui peut ne pas être acceptable dans certains cas. Cette thèse étudie le compromis entre les économies d'énergie et un retard supplémentaire des paquets dans le cas d'un réseau backhaul LTE basé sur réseau optique passif à multiplexage en longueur d'onde (WDM-PON). La thèse propose une nouvelle approche éco énergétique. Elle développe un concept au travers duquel il est possible de contrôler avec précision quand un émetteur doit se réactiver, afin de maximiser le temps passé en mode veille tout en veillant à ce que les transmissions de paquets soient terminées en temps voulu. Le schéma proposé est également capable d’exploiter les (éventuelles) exigences diverses de retard de trafic pour améliorer encore les économies d'énergie. Dans le cœur des réseaux optiques, on peut diminuer la consommation d'énergie en minimisant le nombre d’équipements actifs utilisés pour l’acheminement des circuits optiques et le nombre de liens actifs à fibres optiques. Les stratégies de routage basées sur ce principe sont bénéfiques en termes d'économie d'énergie, mais peuvent affecter les performances du réseau (par exemple, la probabilité de blocage) en affectant la longueur des circuits optiques et la distribution d’occupation des liens. Ce compromis est évalué dans la thèse avec l'aide d’une stratégie de routage et affectation de longueur d'onde (RWA) appelée routage des circuits optiques conscient de la puissance (WPA-LR). La stratégie WPA-LR permet le réglage fin entre deux objectifs: minimiser la consommation d'énergie et minimiser l’utilisation des ressources réseau (i.e. longueur d'onde). Les résultats de l'évaluation confirment que l'efficacité énergétique et les performances du réseau ont des objectifs contradictoires. Cependant, la stratégie WPA-LR proposée permet la minimisation de l'énergie avec un impact acceptable sur les performances du réseau. La thèse étudie également l'impact que les stratégies d’économie d’énergie basées sur le mode veille ont sur la durée de vie d'un certain nombre d’équipements de réseau optique, dans les deux réseaux d'accès et de base. L'utilisation du mode veille peut en effet modifier les conditions de fonctionnement de l’équipement, ce qui peut influer sur la durée de vie de l'appareil. Ceci est un aspect crucial à considérer, car il peut affecter directement le coût opérationnel du réseau lié à la gestion des pannes. La thèse propose une méthodologie pour évaluer dans quelles conditions et pour quels dispositifs un système économe en énergie peut conduire à des avantages de coûts globaux par rapport à une (possible) augmentation des coûts de maintenance. Dans les réseaux d'accès et auprès de clients commerciaux, il a été constaté qu’une petite variation de taux d'échec dans les terminaux de ligne optique (OLT) ou dans les unités de terminaison de réseau optique (ONUs) peut conduire à des pertes financières importantes qui ne peuvent être compensées par les bénéfices provenant des économies d'énergie. Dans les cœurs de réseaux les amplificateurs à fibre dopée en erbium (EDFA) sont les équipements les plus vulnérables en termes d'impact sur leur durée de vie. Pour cette raison, l'utilisation d'algorithmes de routage écoénergétiques basé sur la mise en mode veille des EDFA peut par conséquent n’être pas toujours économiquement avantageuse. En conclusion, cette thèse fournit une perspective différente sur des algorithmes économes en énergie basés sur l’utilisation du mode veille. Leur bénéfice potentiel en termes d'économie d'énergie est comparé à l'impact d'une éventuelle dégradation d’une part de la performance du réseau et d’autre part de la durée de vie des équipements. Ces dégradations de performances peuvent être contrôlées et limitées par les algorithmes proposés.<br>Zużycie energii elektrycznej w sieciach komunikacyjnych stale rośnie. Do tej pory zostało zaproponowanych wiele metod oszczędzania energii na poziomie urządzeń, systemów i sieci. Najbardziej obiecującym podejściem do tego problemu jest wykorzystanie technologii optycznych, z uwagi na ich niskie zużycie energii „per bit”. Ponadto wiele różnych metod przeznaczonych dla sieci optycznych zostało przedstawionych w literaturze. Jedna z popularnych technik wykorzystuje tryb niskiego poboru energii (uśpienia) w urządzeniach, które nie są używane. Jednakże techniki wykorzystujące tryb uśpienia mogą mieć wpływ na kierowanie optycznych połączeń sieciowych (lightpaths) lub zmieniać właściwości urządzeń. Natomiast to może mieć negatywny wpływ na kluczowe parametry wydajności sieci czy urządzeń sieciowych. Innymi słowy algorytmy oszczędzające energię mogą wprowadzić dodatkowe opóźnienia, zmienić wykorzystanie zasobów sieciowych, a nawet wpływać na awaryjność urządzeń zwiekszając tym samym koszt eksploatacji sieci. Praca ta przedstawia i analizuje kompromis pomiędzy korzyściami płynącymi z energooszczędnych algorytmów opartych na trybie uśpienia, a ich ewentualnymi skutkami ubocznymi, zarówno w sieciach dostępowych, jak i szkieletowych. W przypadku optycznych sieci dostępowych proces wprowadzenia urządzenia w tryb uśpienia i jego wybudzenia może spowodować znaczący narzut energetyczny. Proponowane sposoby zmniejszenia tego narzutu agregują ruch sieciowy przed jego transmisją, Jednakże taka agregacja powoduje dodatkowe opóźnienia transmisji, które w niektórych przypadkach mogą być niedopuszczalne. Praca ta analizuje kompromis pomiędzy oszczędzaniem energii, a dodatkowymi opóźnieniami transmisji w przypadku sieci LTE-backhaul, bazowanej na technologii pasywnych sieci optycznych, opartych na multipleksowaniu z podziałem długości fali WDM-PON (Wavelength Division Multiplexing Passive Optical Network). Niniejsza praca proponuje nowatorską metodę oszczędzania energii, opartą na koncepcji drzemki (dozing), która precyzyjnie kontroluje czas wybudzania nadajnika, tak aby zmaksymalizować czas spędzony w trybie drzemki, przy zapewnieniu, że transmisja danych zostanie zakończona przed upływem wymaganego czasu. Proponowana metoda wykorzystuje również zróżnicowane wymagania maksymalnych opóźnień transmitowanych danych do dalszej poprawy wydajności energetycznej. Jednym ze sposobów zmniejszania zużycia energii w światłowodowych sieciach szkieletowych jest zredukowanie liczby aktywnych urządzeń, poprzez umiejętne kierowanie optycznych połączeń sieciowych przy użyciu już aktywnych łączy światłowodowych. Kierowanie ruchu sieciowego oparte na tym pomyśle jest korzystne z punktu widzenia oszczędzania energii, choć z drugiej strony może mieć wpływ na parametry wydajnościowe sieci (np. zwiększenie prawdopodobieństwa blokady połączeń) poprzez oddziaływanie na długość połączeń, czy zajętość łączy. Przytoczony problem jest analizowany w tej pracy za pomocą specjalnie zaprojektowanego algorytmu routingu i przypisania długości fali RWA (Routing and Wavelength Assignement), nazwanego WPA-LR (Weighted Power Aware Lightpath Routing). Algorytm WPA-LR pozwala na precyzyjną regulację pomiędzy redukcją zużycia energii i optymalizacją wykorzystania zasobów sieciowych. Wyniki wykonanej analizy problemu potwierdzają, że efektywność energetyczna i wydajność sieci to cele ze sobą sprzeczne. Jednakże proponowana strategia (WPA-LR) umożliwia kontrolę i osiągnięcie kompromisu pomiędzy zmniejszeniem zużycia energii, a pogorszeniem wydajności sieci. Praca ta bada również wpływ energooszczędnych strategii, opartych o tryb uśpienia, na trwałość optycznych urządzeń sieciowych, zarówno w sieciach dostępowych, jak i szkieletowych. Używanie trybu uśpienia może zmienić warunki pracy urządzenia, które z kolei mogą mieć wpływ na jego trwałość. Natomiast zmniejszenie trwałości urządzenia może bezpośrednio oddziaływać na koszt eksploatacji sieci związany z zarządzaniem awariami. Niniejsza praca proponuje metodologię oceny, na jakich warunkach i w przypadku których urządzeń, używanie algorytmów oszczędzania energii może prowadzić do ogólnych korzyści finansowych lub strat związanych ze wzrostem kosztu eksploatacji sieci. W pracy stwierdzono, że w sieciach dostępowych, w szczególności obsługujących klientów biznesowych, mały wpływ na awaryjność optycznych terminali ONU (Optical Network Unit) lub optycznych urządzeń dystrybucyjnych OLT (Optical Line Terminal) może prowadzić do znacznego zwiększenia kosztów, które mogą przekroczyć zyski związane z oszczędzaniem energii. W sieciach szkieletowych wzmacniacze światłowodowe EDFA (Erbium Doped Fiber Amplifier) są najbardziej wrażliwymi urządzeniami pod względem wpływu na ich awaryjność. W pracy dowiedziono, że użycie energooszczędnych algorytmów kierowania połączeń światłowodowych, opartych na wprowadzaniu EDFA w tryb uśpienia, nie zawsze jest korzystne ekonomicznie. Niniejsza praca przedstawia nowatorskie spojrzenie na energooszczędne algorytmy oparte na wprowadzaniu urządzeń w tryb uśpienia, gdzie potencjalne korzyści w zakresie oszczędzania energii są porównane ze stratami związanymi z degradacją wydajności sieci lub żywotności urządzeń sieciowych.<br><p>QC 20160509</p>

Due to the tremendous growth of traffic volume caused by both exponential increase of number of Internet users and continual emergence of new bandwidth demanding applications, high capacity networks are required in order to satisfactorily handle the extremely large amount of traffic. Hence, optical fiber communication is the key technology for the network infrastructure. This thesis addresses design, analysis and simulation of access and core networks targeting important research problems, which need to be tackled for the effective realization of next generation optical networks. Among different fiber access architectures, passive optical network (PON) is considered as the most promising alternative for the last mile connection due to its relatively low cost and resource efficiency. The inherent bursty nature of the user generated traffic results in dynamically changing bandwidth demand on per subscriber basis. In addition, access networks are required to support differentiated quality of service and accommodate multiple service providers. To address these problems we proposed three novel scheduling algorithms to efficiently realize dynamic bandwidth allocation in PON, along with guaranteeing both the priority and fairness of the differentiated services among multiple users and/or service providers. Meanwhile, because of the increasing significance of reliable access to network services, an efficient fault management mechanism needs to be provided in PON. In addition, access networks are very cost sensitive and the cost of protection should be kept as low as possible. Therefore, we proposed three novel cost-effective protection architectures keeping in mind that reliability requirement in access networks should be satisfied at the minimal cost. Regarding the optical core networks, replacing electronic routers with all-optical switching nodes can offer significant advantages in realizing high capacity networks. Because of the technological limitations for realizing all-optical nodes, the focus is put on the ingenious architecture design. Therefore, we contributed on novel switching node architectures for optical circuit and packet switching networks. Furthermore, we addressed different aspects of routing and wavelength assignment (RWA) problem, which is an important and hard task to be solved in wavelength routed networks. First, we proposed an approach based on the information summary protocol to reduce the large amount of control overhead needed for dissemination of the link state information in the case of adaptive routing. In addition, transparency in optical networks may cause vulnerability to physical layer attacks. To target this critical security related issue, we proposed an RWA solution to minimize the possible reachability of a jamming attack. Finally, in order to evaluate our ideas we developed two tailor-made simulators based on discrete event driven system for the detailed studies of PON and switched optical networks. Moreover, the proposed tabu search heuristic for our RWA solution was implemented in C++.<br>QC 20100707

A comprehensive framework has been developed for designing a GSN. The focus of this thesis is the capacity planning problem which finds the edge capacities for a given physical topology with specifications of the I/O constraints at the nodes. Two kinds of GSN are studied: (1) For the design of a Wide-Sense Non-Blocking GSN (WSNB-GSN), a rigorous mathematical framework is presented. Duality transformation technique that transforms the initial, infinite and infeasible mathematical formulation into a finite feasible formulation is shown. A procedure for finding the realizable lower bound of the cost of a WSNB-GSN is presented and two different solution approaches are proposed. (2) For the design of a Rearrangeably Non-Blocking GSN (RNB-GSN), a straightforward mathematical formulation is presented first. A procedure using the cut condition to find the lower bound of the cost of a RNB-GSN with a general topology is shown then. The optimal solution in the design of a RNB-GSN with an unlimited-size ring topology is demonstrated with a theorem.<br>Dynamic bandwidth provisioning and full survivability against link failures are two of the most important requirements for future optical networks. Since previous methodologies could not deal with these two issues simultaneously, a new survivable network concept called the "Generalized Survivable Network" (GSN) is proposed. Generalized Survivable Network incorporates the non-blocking network concept into the survivable network design. Here, "generalized" means the generalization of a network from satisfying a single demand matrix to satisfying the set of all allowable demand matrices under the Input and Output (I/O) access capacity constraints at the network nodes.<br>Numerical experiments have been carried out to verify the performance of GSN. It is demonstrated that the deploying cost of a WSNB-GSN is within a factor of 2 compared with that of a random sample of a single-period survivable network. The cost of building a RNB-GSN with a ring topology is shown to be about 14% to 45% less than that of building a WSNB-GSN. The framework for planning a GSN is applicable to network planning for future optical networks and survivable IP networks.<br>Ho Kwok-shing.<br>"September 2006."<br>Adviser: Cheung Kwok Wai.<br>Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1823.<br>Thesis (Ph.D.)--Chinese University of Hong Kong, 2006.<br>Includes bibliographical references (p. 118-124).<br>Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.<br>Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.<br>Abstracts in English and Chinese.<br>School code: 1307.

AbstractOptical networks have become indispensable in the era of 5G-and-beyond communications, supporting applications that require unprecedented capacity, reliability, and high Quality-of-Transmission (QoT) of lightpaths. To meet these requirements, network operators strive to provide innovative solutions while managing network costs effectively. This work summarizes the main findings of my Ph.D. thesis Innovative Cross-Layer Optimization Techniques for the Design of Filterless and Wavelength-Switched Optical Networks, that has been conducted in partnership with an industrial partner, SM-Optics. The main objective of the Ph.D. thesis is to investigate solutions to reduce network costs while enabling network expandability through novel network architectures. To ensure cost savings and scalability, (1) we optimize the deployment of Optical Amplifiers (OA) while accurately modeling physical layer impairments in filterless networks, (2) we propose a modular node architecture relying on pluggable devices and a scalable add/drop section at the node level for traffic grooming and capacity increase, and (3) we investigate the application of Machine Learning (ML)—regression approaches to estimate lightpaths’ QoT as they allow to make informed decisions about how conservative or aggressive a network operator can be when taking network planning choices, i.e., deploying a new lightpath. Numerical evaluations show that our proposed approaches achieve significant cost savings compared to benchmark approaches: (1) $${\sim }50\%$$ ∼ 50 % savings in OA cost, (2) $${\sim }50\%$$ ∼ 50 % savings in node architecture equipment cost, (3) $${\sim }70\%$$ ∼ 70 % in penalty costs for deploying wrong lightpath configurations.

Advanced computational techniques are essential for tackling the issues associated with the integration of Distributed Generation (DG) into power distribution networks, especially in the context of modern smart grids and their role in the development of smart cities. This research establishes an extensive framework that integrates probabilistic modeling, multi-objective optimization, and high-performance computing to assess and improve system reliability and economic efficiency. A probabilistic reliability assessment model is introduced to encapsulate the stochastic properties of distributed generation output and load fluctuations, utilizing Monte Carlo simulation to quantify essential reliability metrics such as Expected Energy Not Supplied (ENS) and System Average Interruption Duration Index (SAIDI). An augmented Particle Swarm Optimization (PSO) algorithm is developed to attain a balance between reliability enhancement and cost reduction, using adaptive strategies for superior convergence and solution quality. Simulations performed on an IEEE 33-bus benchmark network demonstrate that increased distributed generation penetration markedly decreases expected non-supply (ENS) and System Average Interruption Duration Index (SAIDI), but with declining results after specific thresholds. Photovoltaic (PV) systems, which utilize optical energy conversion processes, are highlighted as a key DG technology in this study. This research aligns with the objectives of smart cities by enhancing the efficiency, reliability, and sustainability of intelligent power distribution systems. The interdisciplinary approach, which combines probabilistic modeling, optimization algorithms, and high-performance computing, contributes to advancing the integration of distributed generation into future-ready smart grids, addressing the growing energy demands of interconnected urban infrastructures.

In order to solve the problem of poor accuracy of urban power grid load forecasting, the urban power grid load forecasting model and application research based on big data were proposed. In this paper, the long short memory network (LSTM) model is used for in-depth analysis and mining of historical and real-time power grid operation data to improve the accuracy of load forecasting. In addition, genetic algorithm (GA) is used to solve the power dispatching problem to realize the optimal allocation of resources. The experimental results show that the average absolute error (MAE) and root mean square error (MSE) of the LSTM based power grid load forecasting method proposed in this paper are 356.2 and 66.23 respectively, which can better accurately predict the power grid load in the future to a certain extent, thus providing data support for the subsequent implementation of power grid optimal dispatching. Conclusion: The proposed strategy not only improves the operation efficiency of the power grid, but also improves the reliability, economy and intelligence level of the power system from multiple perspectives.

Recent work on integrating sensing functions into optical communication systems is described. The developed techniques are expected to enhance the reliability of optical networks and enable a range of applications in marine and urban environments.

We review the emerging optical network evolution trends to support ubiquitous AI by providing sufficient capacity, latency, flexibility, scalability and reliability, while maximally reusing modern network architectures such as C-RAN and OXC-based 3D mesh connection.

We report the first real-time 128Tb/s co-frequency co-time full-duplex transmission over the first deployed 20km AR-HCFs in complex urban duct network in China by leveraging extremely low distributed Rayleigh backscattering of AR-HCF.

A novel system for automatically detecting leaks in urban water supply networks is proposed and experimentally demonstrated in a real-world scenario. It leverages the extensive fiber optic access network infrastructure already available.

The digital transformation of the management of the transport complex and the growth of the pace of introduction of intelligent transport systems in the cities of the Russian Federation actualize the issue of finding a universal criterion for optimizing the parameters of traffic light regulation on the urban road network. In this article, as a criterion for optimizing network management, an average value of the travel time in the control area, weighted by the length of the path traveled, is proposed. The value of this criterion lies in the universality, as well as the fundamental technical feasibility of its calculation for a real section of the road network in terms of obtaining initial data. In addition, the article emphasizes the fundamental importance of determining this parameter for various conditions. In order to confirm the effectiveness of using the criterion considered in the article, a model experiment was conducted in the SUMO environment, involving a number of experiments for several control methods on the street network at different intensities of incoming traffic flows. On the basis of experimental data, the dependences of the proposed optimization criterion on control methods and the total volume of incoming traffic flows are obtained. The reliability of the criterion was evaluated. The application of the presented criterion in calculating the parameters of traffic light regulation allows you to select the optimal parameters and in the future provide feedback on the implementation of automatic traffic light control on the street and road networks of cities.

The problems of adaptation of energy infrastructure management systems of urban agglomerations to work in emergency situations and in a special period are analyzed. It is proposed to form secure data centers serving the most important infrastructure systems of urban agglomerations, primarily in the field of energy and housing and communal services. The considered technological solutions make it possible to obtain the most optimal ratio of performance and cost of the system in relation to the problem of ensuring the reliability of power supply to urban consumers, taking into account possible critical impacts of a natural and man-made nature, including possible information network attacks.

The field of application of natural gas is very wide. As an energy source, it can be used for energy production in power plants, heating plants and cogeneration plants or for meeting various heat needs in industry and mass consumption. Gas can also be used as a raw material in the chemical and petrochemical industries, and during the last decades it has also been used in traffic as a propellant in SUS engines. From an environmental point of view, natural gas is the most acceptable source of energy compared to other fossil fuels. Due to its chemical composition, the combustion of natural gas emits significantly less carbon dioxide per unit of heat produced, there is no ash and no particulate emissions, and sulfur dioxide emissions are negligible. Natural gas is often called the "fuel of the 21st century" because, in addition to environmental advantages, it also has pronounced technical and economic advantages over other conventional fuels. From a technical and economic point of view, the advantages of using gas are low investment costs and price, high degree of utilization, reliability and flexibility of use, easier and safer storage compared to other fossil fuels. This fuel is available throughout the year, and its quality is standardized and guaranteed. Although the world's proven reserves are abundant, the rational management and use of natural gas is extremely important, given the fact that it is a non-renewable energy source. As it is a flammable and explosive mixture, careful handling and odorization of gas is a prerequisite for safe operation in all plants that use this type of fuel in their operational processes. The contribution of gas to increasing the greenhouse effect can also be singled out as a disadvantage. The aim of this paper is to find the optimal shape of the route of the primary distribution network of gas pipelines in the municipality of Kučevo, defining locations and positions of MMRS and MRS, adoption of supporting equipment for MMRS, pipe sizing based on norms and regulations for medium and high-pressure distribution networks. in supplying both current and future consumers.

The rapid growth in population and related demand for travel during the past few decades has had a catalytic effect on traffic congestion, air quality, and safety in many urban areas. Transportation managers and planners have planned for new facilities to cater to the needs of users of alternative modes of transportation (e.g., public transportation, walking, and bicycling) over the next decade. However, there are no widely accepted methods, nor there is enough evidence to justify whether such plans are instrumental in improving mobility of the transportation system. Therefore, this project researches the operational performance of urban roads with heterogeneous traffic conditions to improve the mobility and reliability of people and goods. A 4-mile stretch of the Blue Line light rail transit (LRT) extension, which connects Old Concord Rd and the University of North Carolina at Charlotte’s main campus on N Tryon St in Charlotte, North Carolina, was considered for travel time reliability analysis. The influence of crosswalks, sidewalks, trails, greenways, on-street bicycle lanes, bus/LRT routes and stops/stations, and street network characteristics on travel time reliability were comprehensively considered from a multimodal perspective. Likewise, a 2.5-mile-long section of the Blue Line LRT extension, which connects University City Blvd and Mallard Creek Church Rd on N Tryon St in Charlotte, North Carolina, was considered for simulation-based operational analysis. Vissim traffic simulation software was used to compute and compare delay, queue length, and maximum queue length at nine intersections to evaluate the influence of vehicles, LRT, pedestrians, and bicyclists, individually and/or combined. The statistical significance of variations in travel time reliability were particularly less in the case of links on N Tryon St with the Blue Line LRT extension. However, a decrease in travel time reliability on some links was observed on the parallel route (I-85) and cross-streets. While a decrease in vehicle delay on northbound and southbound approaches of N Tryon St was observed in most cases after the LRT is in operation, the cross-streets of N Tryon St incurred a relatively higher increase in delay after the LRT is in operation. The current pedestrian and bicycling activity levels seemed insignificant to have an influence on vehicle delay at intersections. The methodological approaches from this research can be used to assess the performance of a transportation facility and identify remedial solutions from a multimodal perspective.