Routing Capacity Research Articles

A Bound on Undirected Multiple-Unicast Network Information Flow

One of the important unsolved problems in information theory is the conjecture that the undirected multiple-unicast network information capacity is the same as the routing capacity. This conjecture is verified only for a handful of networks and network classes. Moreover, only two explicit upper bounds on information capacity are known for general undirected networks: the sparsest cut bound and the linear programming bound. In this paper, we present an information-theoretic upper bound, called the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">partition bound</i> , on the capacity of general undirected multiple-unicast networks. We show that a decision version problem of computing the bound is NP-complete. We present two classes of undirected multiple-unicast networks such that the partition bound is achievable by routing. Thus, the conjecture is proved for these classes of networks. Recently, the conjecture was proved for a new class of networks defined by properties relating to cut-set and source-sink paths. We show the existence of a network outside of this new class of networks such that the partition bound is achievable by routing.

A Location Inventory Routing Optimisation Model and Algorithm for a Remote Island Shipping Network considering Emergency Inventory

This paper studies a hub-and-spoke shipping network of remote islands and integrates a maritime location inventory routing problem for a remote island shipping network considering emergency inventory. By determining a series of decisions, including the location of the hub islands, number of shipping routes, schedule of every route, travelling mode of every route, ship size, wharf scale, and inventory capacity, the objective of this study is to minimise the total cost of the remote island shipping network over the operating period. Subsequently, a mixed-integer programming model to minimise the total cost of the system is developed. To solve the model, we present a genetic algorithm based on a stepwise configuration module (SC-GA). Finally, instances are proposed to evaluate the performance of the algorithm. The results of the instance calculation show that the algorithm has good applicability and effectiveness in solving the problem in this paper. Through algorithm comparison, it is found that the performance of SC-GA is better than the algorithms in the relevant literature. This paper provides practical information for the design, optimisation and sustainability of remote island shipping networks considering emergency inventory.

Crowdshipping: An open VRP variant with stochastic destinations

E-commerce continues to grow throughout the world due to people’s preference to stay at home rather than going to a brick-and-mortar retail store. COVID-19 has exacerbated this trend. Concurrently, crowd-shipping has been gaining in popularity due to both the increase in e-commerce and the current pressures due to COVID-19. We consider a setting where a crowd-shipping platform can fulfill heterogeneous delivery requests from a central depot with a fleet of professionally driven vehicles and a pool of capacitated occasional drivers. We divide delivery requests into sectors to represent different neighborhoods in a city. Occasional drivers have unknown destinations that can be anywhere inside the sectors. Route duration constraints are modeled to motivate participation and increase the probability of route-acceptance by keeping routes short. We assume that occasional drivers will choose routes that are better compensated and that the probability of route-acceptance is dependent on other routes being offered. We propose a two-stage stochastic model to formulate the problem. We use a branch-and-price algorithm capable of solving 50-customer instances, and develop a heuristic that can solve larger 100-customer instances quickly. An upper bound for the total number of occasional drivers is used to reduce the number of constraints in the master problem and reduce the complexity of the pricing problems. We show that occasional drivers with destinations far from the depot reduce the cost by over 30%, while occasional drivers with destinations that are near the depot reduce the cost by 20%. We show that route duration constraints and capacity constraints can restrict the occasional driver routes and both need to simultaneously increase in order to have cost reductions. This setting of crowd-shipping is a viable option for last-mile deliveries.

Congestion-Aware Rectilinear Steiner Tree Construction Using PB-SAT

In this paper, Pseudo-Boolean Satisfiability (PB-SAT)-based congestion reduction and overflow minimization techniques are introduced for constructing congestion-aware rectilinear Steiner trees for global routing in IC design. Since congestion in different routing channels is a big issue in routing nets, various congestion minimization approaches have been proposed by many researchers. However, the increasing complexity of integrated circuits and the reduction of their size make the congestion problem more complicated. The proposed method can produce a congestion-free routing solution by generating a suitable rectilinear Steiner tree for circuit nets. To reduce the complexity of the problem, the nets are solved individually using a Minimum Bounding Box (MBB)-based heuristic technique. The algorithm is validated by utilizing the well-known ISPD 98 global routing benchmarks. Experimental results prove that the methodology is capable of routing most of the nets within the given routing capacity satisfying all the routing parameters. The results also show that the algorithm can produce congestion-aware Steiner trees efficiently within a nominal time-bound.

Optimization for Feeder Bus Route Model Design with Station Transfer

To fully take the advantages of conventional bus and subway, and to maximize the overall feeder efficiency of the public transport system, the topic of feeder bus route optimization is studied in this paper. Considering the origin destination demand of passenger flow between subway stations and bus stations and transfer characteristics, the objective function is established with the minimum sum of bus operation cost and passenger travel cost. Taking into account the integrity of the feeder bus route, the rationality of the route, the route capacity and the station transfer factors, the constraints of the optimization model are constructed. Based on the idea of the genetic algorithm, the solution algorithm of the optimization model is developed. The genetic algorithm and enumeration algorithm are used to solve the optimization of the feeder bus route in this case, and the accuracy and efficiency of the solution are analyzed. The influence of the number of feeder bus routes on the system in the case network is compared and discussed. We compare and analyze the differences between the original bus network and the feeder bus network in terms of bus operation cost, passenger flow demand and total passenger travel cost. The research shows that the model and algorithm can find the approximate optimal solution of the feeder bus network scheme related to the subway through fewer iterations. The number of routes in the model has little impact on the whole feeder system, and the optimization scheme using five routes is effective and reasonable in this paper. Compared with the existing bus network, the optimization scheme has obvious advantages in improving the passenger-carrying rate, reducing the per capita travel cost and improving the overall operation efficiency of the system.

Full-duplex routing with low-complexity sequential-decision for throughput enhancement in dynamic access networks

Integrating the Full-Duplex (FD) communication technology in multi-hop Cognitive Radio Networks (CRNs) can significantly enhance routing decisions such that overall network performance is improved. Unfortunately, when employing the FD technology in multi-hop routing, the channel assignment becomes very challenging due to the possible simultaneous transmissions/reception. Hence, careful low-complexity channel assignment over the various hops along a path is needed to avoid hop-to-hop interference and enhance network performance. In this paper, we propose a low-complexity sequential-decision routing protocol, referred to as Sequential FD (SFD)-aware protocol. The SFD protocol identifies a set of possible routes between any source–destination communicating pair. For each discovered route, SFD successively assigns channels for each hop along the router such that the maximum route capacity is achieved. Then, SFD selects the routes with the highest capacity. Unlike most of existing FD-CRN channel assignment/routing protocols, which require optimization procedures with NP-hard time complexity with the number of channels and hops, the time-complexity of the proposed SFD protocol is polynomial. Compared to the optimal FD-aware routing (obtained using the brute-force search method) and maximum per-hop rate FD-unaware routing protocols, the simulation results confirm the effectiveness of our proposed protocol and its superiority over the existing FD-unaware baseline routing protocol in terms of the end-to-end network throughput. The results also confirm that the SFD protocol provides solutions within 5% of the optimal ones.

A minimal resource high‐speed routing lookup mechanism for servers with NetFPGAs

AbstractThis paper studies how high‐performance computer servers, equipped with Field‐Programmable Gate Arrays (FPGAs), can perform high‐speed routing. In particular, routing table lookup is considered since it is a key packet processing bottleneck for future routers that need to operate at Petabits‐per‐second. The paper defines and evaluates three routing lookup schemes used by routers/switches, using Xilinx NetFPGA SUME programmable data plane hardware boards. Two existing schemes, namely IP address‐based Longest Prefix Matching and Multi‐Protocol Label Switching tag‐based exact matching are implemented. In addition, the paper presents a new routing scheme called No Lookup Forwarding Scheme (NLFS) that does not use conventional lookup tables. The NLFS approach adds a custom routing tag that does not require any form of (forwarding) table lookup, and independent of the Binary/Ternary Content Associate Memory (CAM) capacity in the switch/router. The experimental results show that the NLFS scheme utilizes less FPGA resources, while reducing packet lookup latency by up to 18% against longest prefix match which is the de facto lookup mechanism used in switches. The key contribution of this work is that it enables the use of NetFPGAs to reduce CAM capacity requirements in switches/routers to help reduce memory costs. The proposed scheme has several use cases, including provision of on‐demand increase of packet routing capacity in data center networks and support for Network Function Virtualization‐based systems.

Fast flow algorithm prioritizing the most time-consuming source point by using a multi-source evacuation model

In many public spaces (e.g. colleges and shopping malls), people are frequently distributed discretely, and thus, single-source evacuation, which means there’s only one point of origin, is not always a feasible solution. Hence, this paper discusses a multi-source evacuation model and algorithm, which are intended to evacuate all the people that are trapped within the minimum possible time. This study presents a fast flow algorithm to prioritize the most time-consuming source point under the constraint of route and exit capacity to reduce the evacuation time. This fast flow algorithm overcomes the deficiencies in the existing global optimization fast flow algorithm and capacity constrained route planner (CCRP) algorithm. For the fast flow algorithm, the first step is to determine the optimal solution to single-source evacuation and use the evacuation time of the most time-consuming source and exit gate set as the initial solution. The second step is to determine a multi-source evacuation solution by updating the lower limit of the current evacuation time and the exit gate set continually. The final step is to verify the effectiveness and feasibility of the algorithm through comparison.

Ensuring Secure Routing in Wireless Sensor Network Using Active Trust

Objective: Main objective is to provide a secure router for transferring the valuable data being sensed. One of the major security threats in WSN is the Black hole attack, due to which incoming and outgoing traffic is silently discarded without informing the source that the data did not reach its intended recipient. Overcoming the Black hole attack in WSN is a current research topic. So, the proposed method of trust based secure routing will overcome the black hole attack. Method: The method implemented is integrated as Active Trust to the existing AODV routing protocol to avoid the Black hole attack in WSN. ActiveTrust can relevantly maintain the data route success quality and capacity against black hole attacks and can optimize network lifetime. Findings: Packet delivery ratio and Throughput are measured considering the attack and applying the method implemented. It is noticed that packet delivery ratio is less when there is an attack, and it gets increased when the attack is been rectified by Active trust method. Novelty: Trust based secure routing when compared with existing protocol AODV the attack is reduced and the throughput gets increased by reducing the packet loss. Our approach is efficient in terms of throughput and PDR. As trust factor is so important factor while compared to other factors like Node identity, Node Address etc., our proposed system is efficient. Because node identity can also be spoofed and node address can also be modified by an intruder, but the trust calculation based on the activity of the node cannot be modified by any attacker, because it involves the neighbour node to calculate the trust. Keywords: Black hole attack; AODV; Trust; Secure routing

A hydropedological approach to simulate streamflow and soil water contents with SWAT+

AbstractReflecting internal catchment hydrological processes in hydrological models is important for accurate predictions of the impact of climate and land‐use change on water resources. Characterizing these processes is however difficult and expensive due to their dynamic nature and spatio‐temporal variability. Hydropedology is a relatively new discipline focusing on the synergistic integration of hydrology, soil physics and pedology. Hydropedological interpretations of soils and soil distribution can be used to characterize key hydrological processes, especially in areas with no or limited hydrometric measurements. Here we applied a hydropedological approach to reflect flowpaths through detailed routing in SWAT+ for a 157 ha catchment (Weatherley) in South Africa. We compared the hydropedological approach and a standard (no routing) approach against measured streamflow (two weirs) and soil water contents (13 locations). The catchment was treated as ‘ungauged’ and the model was not calibrated against hydrometric measurements in order to determine the direct contribution of hydropedology on modelling efficiency. Streamflow was predicted well without calibration (NSE &gt; 0.8; R2 &gt; 0.82) for both approaches at both weirs. The standard approach yielded slightly better streamflow predictions. The hydropedological approach resulted in considerable improvements in the simulation of soil water contents (R2 increased from 0.40 to 0.49 and PBIAS decreased from 40% to 20%). The routing capacity of SWAT+ as employed in the hydropedological approach reduced the underestimation of wetland water regimes drastically and resulted in a more accurate representation of the dominant hydrological processes in this catchment. We concluded that hydropedology can be a valuable source of ‘soft data’ to reflect internal catchment structure and processes and, potentially, for realistic calibrations in other studies, especially those conducted in areas with limited hydrometric measurements.

IMPROVED PARTICLE SWAM OPTIMIZATION FOR CROWD SIMULATION USING HYBRID AGENT REINFORCEMENT LEARNING ALGORITHM

In an emergency route planning technique, simulating the dynamic crowd has route capacity constraints and global target of evacuating all crowd evacuees. To stimulate the crowd, the new arena is developed to know the real-time situation to face the crowd evacuation on exit point. The crowd evacuation is done with the process of Hybrid Agent Reinforcement Learning (HARL) algorithm consisting of Improved Multi-Agent Reinforcement Learning (IMARL) and State-Action-Reward-State-Action (SARSA). In the proposed work, the appropriate route selection mechanism focused on finding optimum evacuation route(s) is done in the first phase. Dynamic crowd can also be evacuated to find its way with the support of the HARL process in the second phase. The proposed HARL method can also be implemented with multi-objective improved particle swarm optimization (IPSO) technique for crowd simulation. The experimented results demonstrate the effectiveness of stability in the HARL process, which provides an improved performance for crowd simulation

Potential-based three-dimensional route choice model for pedestrian evacuation on terraced stands

This study proposes a potential-based three-dimensional cellular automata model to describe the route choice behavior of pedestrians while evacuating terraced stands. The model takes into account the pedestrians’ states of sitting, standing, and moving, and the possible transitions on terraced stands. The proposed potential field algorithm reflects the influence on route choice behavior of heterogeneous heights, route distance, pedestrian congestion, and route capacity. Three parameters related to the pedestrians’ behaviors in the spaces with heterogeneous heights are then analyzed to demonstrate the ability of the model to reproduce pedestrian route choice behaviors on terraced stands. Finally, empirical data observed in a terraced stand of a stadium are applied for further validation. The results show that the proposed model performs consistently well with the observed data.

Abstract PO011: Systemic administration of Poly-ICLC promotes T cell tumor infiltration generating antitumor responses

Abstract Background: Recent advances in immunotherapy have revolutionized cancer treatment. Immune checkpoint blockade and adoptive T cell therapy can induce durable responses in some patients. However, the majority of patients fail to respond. Absence of T cell infiltration to the tumor site in solid tumors is considered as one of the major obstacles for effective immunotherapy. Thus, strategies to enhance T cell trafficking and infiltration into the tumor parenchyma is a major research need. Methods: Using a combination of in vivo mouse tumor models and in vitro assays we compared the capacity of various formulations and routes of administration of poly-IC (a dsRNA mimic that functions as a pattern recognition receptor ligand) in enhancing T cell tumor infiltration and generating antitumor responses. Results: Our results showed that poly-ICLC (poly-IC containing poly-lysine and carboxymethylcellulose) enhanced CD8 T cell infiltration into the tumors resulting in the control of tumor growth. These effects relied both on the route of administration as well as on the formulation of poly-IC. Systemic administration (i.v. or i.m.) of poly-ICLC was significantly more effective in inducing CD8 T cell tumor infiltration as compared to intra-tumoral injections. Also, the effects poly-ICLC were substantially more pronounced as compared to unmodified poly-IC. The antitumor effect of poly-ICLC was mediated via MDA-5 and IFN-I, whereas TLR3 stimulation was not required. Interestingly, poly-ICLC stimulated IFN-I responses on tumor vascular endothelial cells (VECs) enhancing the expression of adhesion molecules (VCAM-I), production of IFN-I and T cell recruiting chemokines (CXCL9/CXCL10). Using conditional knockout mice, showed that ablation of IFNab receptors in VECs impaired the antitumor effects of poly-ICLC. IFN-I production upon MDA5 stimulation is required to enhance the secretion of (CXCL9/CXCL10) by VECs indicating that this IFN-I/CXCL9/CXCL10 regulatory axis is crucial for recruiting effector T cells into the tumor parenchyma. The T cell infiltrating effects of poly-ICLC were mainly observed in tumors and not in normal tissues. Conclusions: Systemic administration of poly-ICLC improves T cell infiltration to solid tumors in an MDA5/IFN-I dependent manner. These findings should have a strong impact on improving T cell-based treatments for solid cancers such as adoptive T cell therapy and antitumor vaccines. Citation Format: Hussein Sultan, Juan Wu, Valentyna Fesenkova, Aaron Fan, Diane Addis, Andres Salazar, Esteban Celis. Systemic administration of Poly-ICLC promotes T cell tumor infiltration generating antitumor responses [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PO011.

Planning of coal production taking into account the intensity of shipment and the capacity of transport routes

For effective planning of coal mining at coal mines, it is necessary to take into account the relationship between internal and external processes that occur from the moment of mining the coal to the moment of its sale to consumers. Internal processes are primarily determined by the coordination of operations for drilling and blasting operations, the excavation of mined rock into dumps, the movement of coal to warehouses, its washing and further shipment to railway wagons. External processes are determined by ensuring the delivery of coal to consumers, taking into account the capacity of transport routes, the demand for coal and the price policy in export markets that develops in a certain period of time. Using the example of coal companies that are part of JSC Kuzbassrazrezugol, the article considers a two-level dynamic model for planning coal production, taking into account the intensity of shipment and the capacity of transport routes. At the first level, the volume of coal production intended for export is determined by month, taking into account the intensity of demand for the periods of the year and all restrictions that affect the speed of coal movement to the consumer. At the second level of the system under consideration, the volume of coal sales for export is redistributed over a single time period, taking into account the limitations in the capacity of transport routes, the speed of cargo delivery to the consumer, the level of demand and prices for coal. The use of the dynamic programming method made it possible to solve the problem of redistributing coal sales volumes for export at the second level and, using the results of solving this problem, to determine the optimal volumes of coal production intended for export at the first level.

Organisation of running events – reducing exclusions and improving the quality of life

Physical activity is a basic factor of human development – it brings satisfaction, vitality, energy, has a therapeutic dimension and affects the quality of life. Among the large group of amateur athletes, there are people vulnerable to social exclusions related to disabilities, psychological dysfunctions, sex and social status. For these people sport is a cure for loneliness and lack of self-confidence, as well as it positively affects their motivation to overcome barriers, which is reflected in other spheres of their lives. One sport that in particular integrates different social groups is running, as confirmed by the growing number of amateur runners, training activities dedicated to them and running events organised for them. However, it is important that organisers of such events ensure the safety of participants and take care of their satisfaction and comfort by holistic planning of all organisational activities. The study hypothesised that factors concerning the safety, comfort and satisfaction of participants play a vital role in organising running events. The aim of the article was to identify and assess the risk of organising running competitions for amateurs in the context of ensuring safety and satisfaction for all participants of the event. In particular, the author noted the risk factors of a social nature, conducive to integration, associated with countering exclusions. The paper presents test results for national competitions involving 21 and 42 km runs. The identification of risk factors was performed by 10 experts (the Delphi method) and 27 representatives of 7 running events organised in Poland (2017–2018) (risk estimate, a questionnaire) took part in the risk estimation. Risk estimation was carried out on the basis of average (effect and probability). The results of the study provide unequivocal information about the spheres of organising sporting events which in the highest degree can affect the safety and comfort of their participants and the perception of the competition itself. Among the key risks there were: inadequate financial and organisational resources, route capacity, or technical problems. Moreover, the paper includes an attempt to discuss results of other research.

Evaluation of the return of investments in transport route development

The network of Russian railways provides the movement of goods and passengers both within the country and in the context of international transport, through which goods from different countries go in transit. In Russia the railway lines are double-track and fully electrified on the main directions of the EastWest transport corridor. The modernization of the branches from the Trans-Siberian railway to the state border with China and Mongolia continues. The paper describes the business model of the project, the corresponding calculations for managerial decisions on the launch of a direct train route Novosibirsk – Urumqi and return. During the study, the monitoring of existing routes of passenger traffic was carried out: the capacity of railway routes, frequency, duration and capacity of alternative crossings. The result of the study is a developed model for launching a project of a direct connection between Novosibirsk and Urumqi and return. The paper describes the stations that are of particular importance for the route – the place of customs inspection, rearrangement of wheel sets of cars due to the different wheel gauge of neighboring countries. The result of the study is a multifunctional model of a transport route that allows analyzing the economic parameters of any route of a railway communication. According to the model, it is possible to analyze various parameters of the revenue side of the project, calculate the amount of investments and indicators for the assessment of the effectiveness of real investments.

The Recreational Capacity of the Zones of the Ukrainian National Natural Parks

Purpose. To determine the recreational capacity of the territories of several National Natural Parks (NNPs) of Ukraine, as well as the recreational capacity of the tourist trails of these parks. Methods. The methodological basis of the study is based on a critical analysis of the current approaches to the assessment of a recreational facilities of the Ukrainian NNPs. Various published data sources as well as the data, regarding to the recreational renewal capacity of the territories of the NNPs acquired during own research was used. Results. The area of the reserved core that is larger than a one third of the entire area of the park may be seen in only few parks. Most of the NPPs have an insufficient size of the protected areas. This indicate an unstable and severely disturbed ecological conditions, which threatens the conservation of the biological diversity in these parks. That’s why the increase of the protected areas of these NNPs is highly advisable. In addition to all above, the area of the NNP special use zone should be smaller than the area of the regulated recreational area, which plays a certain environmental role; it can be decreased in a favor of the stationary recreational zone if needed. Unfortunately, these conditions are not met for the most of the studied NPPs. That’s why it is advisable to optimize the functional zoning of the NNPs, which will effectively protect the unique natural complexes and will let use them for the recreational purposes. The capacity, the degree of the resistance to the recreational loads, the level of improvement and the capacity of the tourist routes in each of the spoken NNPs were analyzed. The main criteria for choosing the studied NNPs were their representativeness or representation in terms of a variety of the accommodating regions, the availability of the data based on the physical and geographical characteristics, the length of the tourist routes and the statistcs of the visitors per year. The recreational capacity for the summer season of some NPPs of Ukraine was calculated, while taking into account the standards for each type of the natural complex for the zones of stationary and regulated recreation. Potentially, these zones may be expanded replacing the parts of the reserved special use zone. An assessment of the capacity of some tourist trails of the barely improved NPPs for an unstable and stable category of natural landscape complexes was given. Conclusions. The recreational potential of the researched Ukrainian NPPs is currently underutilized, but with the increase in the flow of the recreants, the recreational areas that are poorly equipped as well as the trails may lead to a deterioration in the state of the natural ecosystems. The functional zones of the stationary and of the regulated parts of the recreational areas of the NNPs may be expanded by migrating some types of the recreational activities to the special use zone of the parks. It is vital to expand the list of the recreational services for recreants, to strive the level of improvement of the tourist trails of the NNPs. If the natural healing resources are present on the territories of the NNPs, it is advisable to organize some centers for the sanatorium treatment, medical and socio-psychological rehabilitation, which will contribute to the creation and an improvement of the medical and the health infrastructure, the activation of recreational activities and the increase in the efficiency of the functioning of the NNP.

Improving the Operational Efficiency of Parcel Delivery Network with a Bi-Level Decision Making Model

This article proposes a mathematical model for integrating terminal operation strategies with shipment scheduling. We are motivated by findings from the literature on the integrated design of logistic systems. The objective of this research is to efficiently utilize the existing hub terminals and transport network by considering the minimization of costs related to terminal congestion, transport, and carbon dioxide (CO2) emissions. Cooperative behaviors of terminal managers and fleet assignment managers are modeled in a bi-level problem framework. The total cost includes a processing cost and transport cost, and CO2 related to the assigned fleets. We introduce a terminal cost function to capture the relationship between unit processing cost with respect to hub delay, which allows us to find the minimum cost path and efficiently distribute shipments to hub terminals. The case study shows that the collaborative logistics outperforms a single routing strategy and capacity expansions in minimization of both total cost and CO2 emissions.

Dam Safety: Sediments and Debris Problems

Sedimentation of reservoirs has its negative impacts on dams, first by reducing useful storage, altering the benefit/cost ratio originally calculated for the dam, and second by reducing the dams’ capacity for flood routing; increasing flooding hazards on the dam itself and for the downstream. More problems can be created by sediments and floating debris during floods on outlet structures by clogging them and thus creating dangerous situations, or damage trash screens leading to even more problems. If these debris and coarse sediments are allowed in, then they may damage dam structures such as gates, spillways intakes in addition to chutes, stilling basins and power penstocks by the mechanical abrasion impacts of such sediments on them. Frequent inspections, especially after floods must be made to ensure proper functioning of such structure and take actions for reducing the damage. In small reservoirs, dredging; although it adds to maintenance cost, may ease the problem, but in very large reservoirs, this may prove unpractical. Designers, therefore, have a duty to consider sedimentation problem seriously in the initial stages of design by: checking the anticipated accumulation of sediments, allowing enough storage free from siltation, foreseeing their negative impacts on intakes and outlet structures and taking design measures to reduce these impacts. At the same time, dam stability calculations shall have to provision for the anticipated new conditions of silting up at the face of the dam. Operators of dams, on the other hand, shall have to keep open eyes for all the negative issues created by sediments and floating debris, repairing damages caused by them and take measures to reduce their impacts in the future.

Quantifying the Impact of Time-Sharing on Route Capacity in Cognitive Radio Networks With Full-Duplex Capability

Recent advances in full-duplex (FD) communications along with the introduction of the concept of device-to-device communications have challenged the applicability of traditional routing and scheduling schemes in multi-hop cognitive radio networks (CRNs). In this letter, we derived a close-form expression to quantify the impact of time-sharing of a given channel assignment along a given path on network performance. Based on the derived expression, we mathematically model the channel-assignment problem that minimizes the number of time-shared hops along a given path as a binary-quadratic optimization problem (BQP). Then, we transfer the BQP into a binary linear programming problem (BLP), which is sub-optimally solvable using a polynomial-time sequential fixing method. Simulation results indicate that routing with assignment that minimizes the needed number of time-shared transmissions along a path can provide significant improvement in network throughput.