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Smart grids are one of the most important structures based on cyber–physical devices. Therefore, these grids should be more reliable and efficient when increasing consumption. In recent years, however, with the automation of power grids and data transferring in a telecommunications infrastructure, the possibility of planning cyber-attacks has become a significant threat to systems integrity. Well-planned cyber-attacks can have catastrophic effects on the system to the extent that they may lead to a global blackout. It has been proven that, the optimization of the budgets for attack and defense in a power grid through cyber-attack is so essential. The aim of the present paper is investigate and simulate the most vulnerable operating bus using the state estimation technique through a new algorithm. The false data injection is performed on the data sent from the Phasor Measurement Units in such a way that it is not detectable to the grid dispatching operator under the invasion. In other words, when a cyber-attack occurs, the defender does not notice the attack and thus the estimated modes are destroyed. The proposed algorithm is implemented on a 14 IEEE bus network, and the best bus in terms of exposure under attack is identified. The proposed algorithm is based on the results obtained from state estimating of the grid after occur a cyber-attack on different buses. It was found that, the best bus to carry the attack was bus number 5, which causes the most changes in state variables with the least measurement damage. In addition, the most damage to the grid occurs when a cyber-attack causes the most damage in estimating the state of the most grid state variables.

On a transit route, initiating a trip beyond a transit route’s departure terminus and terminating the trip before its arrival is called “short-turn.” This study develops a method to design short-turn services to alleviate crowding on a transit network consisting of multiple overlapping routes. The proposed method consists of two processes: (i) optimizing routes, turn-back points, and fleet sizes of short-turn services by a genetic algorithm to minimize the sum of waiting, in-vehicle, operation, and social costs; (ii) assigning passenger trip demands to short-turn and existing services. These processes are performed iteratively to design multiple short-turn routes. The proposed method is applied to a real-world transit network in Seoul, Republic of Korea, to design 10 short-turn routes. The results are compared with two naïve methods that introduce short-turn services to sections with the maximum occupancy and the maximum demand divided by the section length, respectively. The comparison results show the proposed method is much superior to both of the naïve methods in reducing total costs. The result of the sensitivity analysis suggests that the value of in-vehicle time needs to be estimated accurately and site-specifically. The proposed model contributes to enhancing the convenience of transit users by effectively mitigating the crowding under budget constraints.

This article presents a mathematical model to design a demand-responsive connector (DRC) bus operational network for improving the service quality and accessibility of public transportation systems. The proposed model features an integrated framework that simultaneously guides passengers to reach their nearest bus stops and routes buses to transport passengers at selected bus stops to connected stations of major transit systems. Passengers’ preferred time for pick up is fully considered in the model. For this purpose, this study proposes a multi-objective mixed-integer linear programing model to effectively capture the interactions between users with their predefined service time windows and DRC bus network. This study further develops a three-stage heuristic to yield suboptimal solutions to the model in a reasonable time. Case study results demonstrate the effectiveness of the proposed model.

The Industry 4.0 paradigm conceives a cyber-physical supporting framework for the manufacturing processes in smart factories. In this context, solutions concerning the wired communications at the field-level have been reported which utilize either fieldbuses, which exhibit a huge distance range but a reduced data rate in a bus topology, or Ethernet-based technologies, which provide an increased data rate but reduced distance in a ring topology. To overcome this shortage, we propose the use of orthogonal frequency division multiplexing (OFDM) to significantly increase the achievable data rates over large distances in industrial bus systems. Also, we establish a novel methodology to compute the signal-to-noise ratio between arbitrary pairs of nodes, which in turn allows to compute the communication capacity. Our wideband system was validated by connecting up to 32 nodes in the distance range 100 m–1 km. Compared to fieldbuses, the results of the proposal exhibit an amazing improvement in data rate of about fifty times for 100m distance and more than ten times for 0.5 km. Moreover, with respect to Ethernet-based solutions, the results show a relevant improvement in the data rate of around five times for 100m distance, but Ethernet-based systems cannot go beyond this distance, to which our proposal is not limited. This work was supported in part by the Elektromobilität mit Redundanter Intelligenter Kommunikations-Architektur (ERIKA) Project, in part by the Bundesministerium für Wirtschaft und Energie, Germany, in part by the Spanish National Project Hybrid TERrEstrial/Satellite Air Interface for 5G and Beyond-Areas of Difficult Access (TERESA-ADA) (TEC2017-90093-C3-2-R) through Ministerio de Economía y Competitividad (MINECO)/Agencia Estatal de Investigación (AEI)/Fondo Europeo de Desarrollo Regional (FEDER), Unión Europea (UE), and in part by the CORE project Cognitive Cohesive Networks of Distributed Units for Active and Passive Space Applications (COHESAT) through the Fonds National de la Recherche (FNR), Luxembourg.

Travel demands in remote areas are scattered and unstable. Thus, the integration of different types of transportation can be beneficial for improving the service level of transportation systems in ...

The integration of subway and bus networks has become an effective solution to reduce the growing congestion. This study presents a practical scheme of multiple subway line design to obviate the di...

Intelligent management of the electrical network is the implementation of an integrated system based on a reliable and secure communication architecture for transmitting end-to-end information between the equipment and the management system. The main objective of this work is to develop an intelligent telecontrol solution for the electrical distribution network combining communication techniques and an intelligent reconfiguration strategy. The solution is based on a graphic model and a secure communication architecture using the internet of things to ensure flexibility in terms of management of the intelligent network. This intelligent multi-criteria solution uses a secure communication architecture and the MQTT protocol to ensure system interoperability and security. The tests were carried out on the IEEE 33 bus network and consequently, an optimization of the losses and a clear improvement in the nodal voltage were recorded despite the variation of the electric charge.

Many complex networks exist to facilitate the transport of material or information. In this capacity, the authors are often concerned with the continued flow of material or information when a fraction of the links in the complex network is disrupted. In other words, the authors are interested in the robustness of the complex network. In this paper, the authors survey measures of robustness like the average path length, the average clustering coefficient, the global efficiency, the size of largest cluster and use these to analyze the robustness of the bus network in Hanoi, Vietnam. The authors find that the bus network is robust against random failure but sensitive to targeted attack, in agreement with its scale-free character. By examining sharp drops in the average path length within the largest cluster of the Hanoi bus network under successive targeted attack, the authors identify five nodes whose loss lead to the fragmentation of the network into five or six disconnected clusters. These isolated clusters represent geographically the Central, Western, Southern, and Northwestern districts of Hanoi. Special considerations must therefore be given to these five nodes when planners wish to expand the bus network, or make it more robust. Accepted version

Connecting points of interest through a well-planned, inter-connected network provides manifold benefits to commuters and service providers. In the South African context, traffic congestion has become of great concern. Given how the South Africa community is slowly developing towards the use of multi-modes of mobility, the Gautrain network can be used to promote the use of multi-modes of mobility, as the Gautrain has been identified as the backbone of mobility within the Gauteng province. Currently commuters have the option to board the Gaubus (a form of Bus Rapid Transit) at their origin points which will take them to the Gautrain station to board the Gautrain. The problem to be solved arises when a commuter wishes to traverse from any bus stop to the Gautrain station, currently he/she only has one option and if the bus network has a shutdown at any point in the network the commuter’s journey will not be possible. In solving this problem, we consider the problem of graph robustness (that is creating new alternative routes to increase node/bus stop connectivity). We initial use Strava data, to identify locations were cyclist prefer to cycle and at what time of day. In graph theory, the nodes with most spreading ability are called influential nodes. Identification of most influential nodes and ranking them based on their spreading ability is of vital importance. Closeness centrality and betweenness are one of the most commonly used methods to identify influential nodes in complex networks. Using the Gaubus network we identify the influential nodes/ bus stops, using the betweenness centrality measure. The results reveal the influential nodes with the highest connectivity as these have cross-connections in the network. Identification of the influential nodes presents an important implication for future planning, accessibility, and, more generally, quality of life.

Compared with other spacecrafts, there are many bus networks and many interactive data. Moreover, it has the bus network connection and data management functions among the three space station capsules, and the manned spaceships and cargo spaceships. Aiming at the problem of data management of space station bus network which can be combined and separated dynamically, through the design of multi-level bus networks and docking bus networks in the capsule, the data management solution is given from the system level. The process of telemetry management, telecommand management and interactive data management between subsystems are described in detail. Through the unified protocol design and routing management, the integrated networking and data communication between the spacecrafts are realized, which reduces the complexity and test difficulty of the system. This method has been tested and verified in the space station task, which not only ensures the reliability of docking and separation between the space station capsules, but also takes into account the flexibility and expansibility of data management.

The 1553B bus is widely used in spacecraft avionics system for its high reliability. The single point of failure (SPOF) of bus controller (BC) leads to the bus network paralysis. To improve the service continuity of the bus network, an autonomous inter-device bus control transfer protocol is proposed. The remote terminal (RT) address is used to identify device and initialize it with constant priority and timing parameters. In the situation of start-up and BC failure, the highest priority device autonomously acquires bus control, and the bus communication is self-repaired. After the fault device fixed, the bus control can be transferred under command control. In this paper, the realization scheme, the software implementation and the verification test of proposed protocol is introduced.

The need to guarantee a real-timed reconstruction, modification and repair of unrecoverable request-to-send/clear-to-send (RTS/CTS) sensitive data packets in a typical military standard (MIL-STD-1553) network protocol for an industrial internet of battle things (IIoBT) is a major research concern. A technique to reconstruct unrecoverable data in a military standard MIL-STD-1553 bus network protocol, using Bezier curves is presented in this paper. The proposed approach approximates and reconstructs nearly unrecoverable/damaged data, using the error correction code technique. Reliability of the MIL-STD-1553 bus network is guaranteed for all the distributed systems in use, especially in cases where packet re-transmission is not an optimal solution for packet failure and other related drawbacks. Simulation results presents optimal Bezier curve performance as against other investigated packet re-transmission methodologies.

In Industrial Control Systems, isolated proprietary networks are widely used to prevent cyber attacks from Internet. However, the attack can bypass it by connecting external devices into networks, named as device-connected attack. In field bus networks, this attack is hard to be prevented but easy to be implemented. In this paper, the physical intrusion detection is proposed against the device-connected attack. Rather than the network traffic in network intrusion detection, the impedance of whole system and voltage signals are applied to detect the device-connected attack, which would be slightly changed when the external devices are connected. The demo system is implemented on RS485 bus network to demonstrate the effectiveness of proposed method.

Feeder-bus networks between urban rail transit systems and bus stops are inefficient in terms of the cost incurred by passengers, the time taken to reach the destination, and the number and...

LoRaWAN is one of the leading Low Power Wide Area Network (LPWAN) architectures. It was originally designed for systems consisting of static sensor or Internet of Things (IoT) devices and static gateways. It was recently updated to introduce new features such as nano-second timestamps which open up applications to enable LoRaWAN to be adopted for mobile device tracking and localisation. In such mobile scenarios, devices could temporarily lose communication with the gateways because of interference from obstacles or deep fading, causing throughput reduction and delays in data transmission. To overcome this problem, we propose a new data forwarding scheme. Instead of holding the data until the next contact with gateways, devices can forward their data to nearby devices that have a higher probability of being in contact with gateways. We propose a new network metric called Real-Time Contact-Aware Expected Transmission Count (RCA-ETX) to model this contact probability in real-time. Without making any assumption on mobility models, this metric exploits data transmission delays to model complex device mobility. We also extend RCA-ETX with a throughput-optimal stochastic backpressure routing scheme and propose Real-Time Opportunistic Backpressure Collection (ROBC), a protocol to counter the stochastic behaviours resulting from the dynamics associated with mobility. To apply our approaches seamlessly to LoRaWAN-enabled devices, we further propose two new LaRaWAN classes, namely Modified Class-C and Queue-based Class-A. Both of them are compatible with LoRaWAN Class-A devices. Our data-driven experiments, based on the London bus network, show that our approaches can reduce data transmission delays up to $25\%$ and provide a $53\%$ throughput improvement in data transfer performance., Comment: Accepted for publication at ICDCS 2020

Hub stations and important lines play key roles in transfers between stations. In this paper, a node failure model is proposed to identify hub stations. In the model, we introduce two new indicators called neighborhood degree ratio and transfer index to evaluate the importance of stations, which consider neighborhood stations’ degree of station and the initial transfer times between stations. Moreover, line accessibility is developed to measure the importance of lines in the bus network. Xiamen bus network in 2016 is utilized to test the model. The results show that the two introduced indicators are more effective to identify hub stations compared with traditional complex network indicators such as degree, clustering coefficient and betweenness.

Public transport networks (PTNs) undertake large amount of passenger demand in the urban transport system. Particularly, stations in metro networks with high significance in structure and function are more likely to contribute to passenger transport. Once these stations are under functional failure, it is easy to lead to the collapse of network connectivity. Thus, identifying critical nodes in PTNs is of practical significance for the public transport planning and operation. This study proposes an identification method for the critical nodes in multiplex network by considering the interaction between metro and bus networks. First, metro and bus networks are constructed by L-space and P-space methods, respectively. Then, ridership is extracted to describe the connection between nodes as the weights of links, and the metro-bus multiplex network is then constructed. Furthermore, the identification method in Multiplex Network based on Dempster–Shafer evidence theory (MNDS) is proposed to fuse the significance of nodes in sub-networks, and the critical nodes in the multiplex network are identified. Finally, the PTNs in Shenzhen City, China, is used as a case to demonstrate the feasibility of MNDS. By attacking critical nodes, a comparison is conducted and compared with two traditional identification methods (Weighted Closeness Centrality and Technique for Order Preference by Similarity to Ideal Solution) using two indicators, global efficiency (GE) and the size of the largest connected component (LCC). The results indicate the critical nodes identified by MNDS are of greater significance than those identified by the other two methods. This study provides a feasible method for critical nodes identification in urban public transport system, which can be applied to public transport operation and planning.

Compared to general vehicular systems, bus systems have advantages including wide coverage, fixed routes, and regular service. Inspired by these unique features of the bus systems, we propose to use the bus systems as routing backbones of VANETs. In this work, we present a Community-based Bus System (CBS) which consists of two components: a community-based backbone and a routing scheme over the backbone. The backbone construction is a one-off operation which is done offline while the routing is done online in individual buses. We build a community-based backbone by applying community detection techniques and propose a two-level routing scheme which operates over the backbone. The proposed routing scheme performs sequentially in the inter-community level and the intra-community level, and is able to support message delivery to both buses and specific locations/areas. We develop a probabilistic model to analyze the message delivery latency of CBS. The average error of the analytically-derived latency is shown to be 8.9 percent of the latency derived from the real traces. Extensive experiments are conducted on real-world traces from the Beijing bus system and the Dublin bus system and the results show that CBS can significantly lower the delivery latency and improve the delivery ratio, compared to the existing solutions. CBS is a general solution which is applicable to any bus-based VANETs.

With the recent rapid improvement of wireless communication technology, wireless network gains increasing interest as a train backbone in order to provide the passenger service as well as the original real-time control duties. To use the wireless network as a train backbone, however, the existing standard protocol, IEC Std. 61375 Train Communication Network(TCN), needs to be modified to reflect the wireless-specific characteristics because it was originally designed for the wired network such as switched Ethernet. The train topology discovery protocol(TTDP) that provides automatic network reconfiguration is one of the key TCN protocols to be modified to support a wireless train bus. This paper proposes a modified topology discovery protocol that can be used for a train-wide wireless LAN. Proposed protocol finds the bus topology based on the radio signal strength with maintaining the existing standards and controls the transmit signal power to avoid overhearing problem in wireless network. The time bound to build network topology using the proposed protocol is also estimated by computer simulation.

Traditional network architecture is inflexible and complex. This observation has led to a paradigm shift toward software-defined networks (SDNs), in which the network control level is separated from the data link layer. This change became possible because of the control plane transfer from switching equipment to software modules that run on a dedicated server called a controller (or a network operating system) or to network applications that work with this controller. Methods of presentation, storage, and communication interfaces with network topology elements available to SDN controller users are the most important aspects of network operating systems because the operation of some key controller modules depends heavily on the internal representation of the network topology. Firewall and routing modules can be cited as examples of these modules. This paper considers the methods used to represent and store the network topology, as well as communication interfaces with corresponding modules of the Floodlight controller. An alternative algorithm for exchanging messages on the changes in the network topology between the controller and network applications has been proposed and developed. The algorithm makes it possible to issue notifications based on a subscription to relevant events. An API for the module of interacting with applied programs of the SDN controller has been developed. The Topology Tracker module has been designed based on this algorithm and API. In active mode, this module can inform network applications about the changes in the network topology and store its compact representation for the interaction acceleration.

Transit networks are essentially temporal with their topology evolving over time. While there are several studies on the topological properties of bus transit networks, none of them have captured the temporal network characteristics. We present a temporal analysis of a bus transit network using snapshot representation. We propose a supply-based weight measure, called the service utilization factor (SUF), and define it as the passenger demand per trip between two bus stops. We evaluate the complex network properties in three weighted cases for a bus network in India, using the number of overlapping routes, passenger demand between routes and SUF as weights. The study network is well-connected with 1.48 number of transfers on average to travel between any two stops over the day. The temporal analysis indicated an inadequate number of services in peak periods and route redundancy across the time periods. We identified the existing and potential hubs in the network, which were found to vary across time periods. The network has strongly connected communities that remain constant across the day. Our conclusions exemplify the importance of temporally analyzing transit networks for improving their efficiency.

Currently, TTEthernet supports 2 topologies: Star and Ring. Network components that can be found in TTEthernet network are switches and end systems. In this paper, we discussed about possibilities for using Hub topology in TTEthernet networks. The concept of TTEthernet operation is described, as well as necessary adaptations to be done for Hub topology support. Alongside with that, advantages and lacks of this approach are discussed, whence we can conclude whether this topology is acceptable at all in domain of TTEthernet networks applications. It is shown that reliance of the complete TTEthernet network only to bus topology is not a good option, because of lower fault-tolerant abilities. Possible application could be a mixed-topology, where bus topology will be used for low-critical traffic, while star of ring topology will be used for high-critical traffic.

The technological rise in public transportation is on the horizon, but the bus network structure and intelligent bus tracking system should first be in place. Bus transport service is on the edge of digital revolution, generating real-time tracking information about the bus service using smartphones. In this paper, a cloud-based bus tracking system based on IoT is proposed to reduce human intervention, waiting time and energy. The exact location and arrival time of the bus can be tracked dynamically by using a mobile application to provide better and efficient bus service. Furthermore, passengers can buy tickets without queueing and book the available seats by making online payments. The proposed scheme allows more flexibility and user satisfactory service to the rider in terms of time loss and encourages more people to ride by providing real-time bus tracking information to improve passenger satisfaction. The main objective is to minimize the unnecessary waiting and queueing time uncertainty of passengers. Riders can utilize their waiting time more productively by choosing the nearest route and alternative transportation. The sustainability of public transport service can be maintained by providing noteworthy benefits to the passengers using the proposed IoT-based bus tracking system.

The demand for Internet services that require frequent updates through small messages, also known as microblogging, has tremendously grown in the past few years. Although the use of such applications by domestic users is usually free, their access from mobile devices is subject to fees and consumes energy from limited batteries. If a user activates his mobile device and is in the range of a publisher, an update is received at the expense of monetary and energy costs. Thus, users face a tradeoff between such costs and their messages aging. The goal of this paper is to show how to cope with such a tradeoff, by devising aging control policies. An aging control policy consists of deciding, based on the utility of the owned content, whether to activate the mobile device, and if so, which technology to use (WiFi or cellular). We present a model that yields the optimal aging control policy. Our model is based on a Markov Decision Process (MDP) in which states correspond to content ages. Using our model, we show the existence of an optimal strategy in the class of threshold strategies, wherein users activate their mobile devices if the age of their poadcasts surpasses a given threshold and remain inactive otherwise. The accuracy of our model is validated against traces from the UMass DieselNet bus network.

Modern IoT devices are equipped with media-rich sensors that generate a heavy burden to local access networks. To improve the efficiency of data collection, we introduce the concept of "IoT zones" as geographically-correlated clusters of local IoT devices with well connected wireless networks that may have limited access to the Internet. We develop techniques to create a cost-effective data collection network using existing transportation fleets with predefined schedules to collect sensor data from IoT zones and upload them at locations with better network connectivity. Specifically, we provide solutions to the upload point placement and upload path planning problems given tradeoffs between collection quality, timing needs (QoS), and installation cost. We evaluate our approaches using a real-world bus network in Orange County, CA and study the applicability and efficiency of the proposed method as compared to several other approaches. The trace-driven simulations reveal that our best-performing algorithm: upload point selection (UPS) algorithm significantly outperforms others, e.g., in one of the scenarios with 160 total cost, it achieves sub-21 sec data transfer time (15+ times improvement), sub 3.2% late delivery ratio (about 12 times improvement), and above 96% data delivery ratio (about 50% improvement). In addition, it achieves the above performance without excessive installation cost: even when a cost limit of 640 is given, UPS algorithm opts for a solution with about 160 total cost (versus 640 from others).

In order to promote the integration of automobile network and Internet, Internet of Vehicles gateway plays an important role in connecting vehicle-borne network and Internet. In view of the current developers using traditional development methods to achieve Internet of Vehicles gateway software, a new implementation scheme -- real-time Java technology is introduced. This paper takes the AMD Opteron 1150 processor based on the ARM Cortex-A57 architecture as the core to build the hardware platform of the Internet of Vehicles gateway, and gives the overall structure diagram and hardware connection scheme of the Internet of Vehicles system. The gateway adopts the networking scheme of "4G+ sensor network technology/field bus" and realizes wireless data interaction on the basis of real-time operating system. In addition, the data communication of Internet of Vehicles (three-layer communication structure) is realized on the WebSphere Real Time development platform that is fully compatible with RTSJ, so as to realize data sharing between the automobile bus network and the Internet. Finally, the implementation technology and system verification of the design are given.

Purpose Increase in the speed of processors has led to crucial role of communication in the performance of systems. As a result, routing is taken into consideration as one of the most important subjects of the network-on-chip (NOC) architecture. Routing algorithms to deadlock avoidance prevent packets route completely based on network traffic condition by means of restricting the route of packets. This action leads to less performance especially in non-uniform traffic patterns. On the other hand, true fully adaptive routing algorithm provides routing of packets completely based on traffic conditions. However, deadlock detection and recovery mechanisms are needed to handle deadlocks. Use of a global bus beside NOC as a parallel supportive environment provides a platform to offer advantages of both features of bus and NOC. Design/methodology/approach In this research, the authors use this bus as an escaping path for deadlock recovery technique. Findings According to simulation results, this bus is a suitable platform for a deadlock recovery technique. Originality/value This bus is useful for broadcast and multicast operations, sending delay sensitive signals, system management and other services.

Multi-processor systems need interconnection networks (INs) in order to make the connection among the processors, memory modules, and nodes. Bus interconnection network is the simplest and least expensive one among all the INs. Therefore, bus network is easily understood and preferred by manufactures for implementation. However, a bus network is inherently a non-fault tolerant and blocking network. To cope with these problems, a solution is to use several buses in parallel on a network. Based on this idea, various schemes can be designed for a bus network: (1) Multiple-bus with full bus-memory connection, (2) Multiple-bus with single bus-memory connection, (3) Multiple-bus with partial bus-memory connection, and (4) Multiple-bus with class-based memory connection. On the other hand, a metric for the efficiency of fault-tolerant systems is its reliability. Although, there is no detailed analysis of the reliability of bus-based networks, this paper presents accurate and complete reliability analysis of bus-based networks to achieve these aims: (1) Determining the most efficient design of bus-based networks in terms of reliability, cost-effectiveness, and blocking issues, (2) Providing new methods for evaluating the performance of bus-based networks.

Akin to most infrastructures, intraurban bus networks are large and highly complex. Understanding the composition of such networks requires an intricate decomposition of the network into modules, taking into account the manner in which network links are distributed among the nodes. There exists for each set of highly interlinked nodes little connectivity with the next set of highly interlinked nodes. This inherent property of nodes makes community detection a popular approach for analyzing the structure of complex networks. In this study, we attempt to understand the structure of the intraurban bus network of Ireland’s capital city, Dublin in a two-step approach. We first analyze the modular structure of the network by identifying potential communities. Secondly, we assess the prominence of each network node by examining the module-based topological properties of the nodes. Results of this empirical study reveal a clear pattern of independent communities, indicating thus, an implicit multi-community structure of the intraurban bus network. Examination of the geographic characteristics of the identified communities shows a degree of socio-economic divisions of the Dublin city. Furthermore, a large majority of the important nodes (vital transportation hubs) are located at the city center, implying that most of the bus lines in Dublin city tend to intersect the city’s core.

For higher reliability against a link failure of a control network in railway vehicles, a recovery mechanism is needed. We introduce a problem that, when a link failure occurs in a ring-topology control network, a node may experience a significant increase of transmission delay depending on its relative position within the network. We then propose two mechanisms to solve this problem: (1) differentiating and prioritizing node traffic in forwarding; and (2) switching some nodes to a backup bus-topology network. Our simulation study shows that, while the first mechanism achieves a limited gain by only compensating queuing delay, the second one gets a sufficient gain which is impacted by the number of nodes switched to the bus network.

Software-defined networking (SDN) has emerged as a new network architecture, which decouples both the control and management planes from data plane at forwarding devices. However, SDN deployment is not widely adopted due to the budget constraints of organizations. This is because organizations are always reluctant to invest too much budget to establish a new network infrastructure from scratch. One feasible solution is to deploy a limited number of SDN-enabled devices along with traditional (legacy) network devices in the network of an organization by incrementally replacing traditional network by SDN, which is called hybrid SDN (Hybrid SDN) architecture. Network management and control in Hybrid SDN are vital tasks that require significant effort and resources. Manual handling of these tasks is error prone. Whenever network topology changes, network policies (e.g., access control list) configured at the interfaces of forwarding devices (switches/routers) may be violated. That creates severe security threats for the whole network and degrades the network performance. In this paper, we propose a new approach for Hybrid SDN that auto-detects the interfaces of forwarding devices and network policies that are affected due to change in network topology. In the proposed approach, we model network-wide policy and local policy at forwarding device using a three-tuple and a six-tuple, respectively. We compute graph to represent the topology of the network. By using graph difference technique, we detect a possible change in topology. In the case of topology change, we verify policy for updated topology by traversing tree using six-tuple. If there is any violation in policy implementation, then affected interfaces are indicated and policies that need to be configured are also indicated. Then, policies are configured on the updated topology according to specification in an improved way. Simulation results show that our proposed approach enhances the network efficiency in term of successful packet delivery ratio, the ratio of packets that violated the policy and normalized overhead.

We present a complex weighted network analysis of a bus transport network. We model the network as graphs in L-space and P-space and evaluate the statistical properties in unweighted and weighted cases. The weights considered include number of overlapping routes and passenger demand between two bus stops. We also introduce a new supply-based edge weight called Service Utilization Factor ( S U F ) and define it as the passenger demand per service between two stops. We extract the origin and destination of the passenger trips from bus ticket information. In the bus system under study, the tickets are issued between ’stages’ instead of between bus stops. We propose a points of interest based procedure to map the passenger demand between stages to between bus stops. The network has scale-free behaviour with preferential attachment of nodes and is similar to small-world networks. It is well-connected with an average of 1.4 transfers required to travel between any two points in the network. We identify redundant routes in the network from strength values in the SUF weighted networks. Disassortativity in the demand weighted network indicated that bus stops with higher attractiveness are not necessarily situated contiguously along a route. The SUF weighted network is assortative indicating presence of well-serviced stops along the same the route. We identified the stops with higher betweenness centrality, that can be ideal candidates for being developed as hubs. Our conclusions exemplify the importance of considering route overlaps, passenger demand and service utilization in bus network analysis and for building an efficient bus network.

Graph analysis approach was used to analyze a city bus network. The bus trip data were segregated into 4 smaller bus datasets (weekday-peak-hour, weekday-off-peak-hour, weekend-peak-hour, and weekend-off-peak-hour) with the main goal of studying and identifying the differences between peak hours and off-peak hours, as well as between weekdays and weekends. These differences are identified in terms of global characteristics and network evolution distinctions. Based on the analysis of the simplified network, we identified the relative shape of the networks and the centrality attributes. A comparative analysis is performed between the networks at different times to understand the impact of peak against off-peak and weekday against weekends. Significant differences are found in the analysis. In addition to the above, highly important routes and stops were also identified, where optimization initiative is planned for a more efficient bus transport network. The findings can serve as a starting point for future route optimization of the similar network.

This paper introduces an IoT-based bus location system that can improve the service quality of the bus network and improve the efficiency of operation management. The proposed system provides the bus approach information by utilizing the location and delay information of the bus, and can be realized with low operational cost. The principle of LoRaWAN is used to collect the location information of all buses and deliver the calculated delay information to smart bus stops using electronic paper. A prototype system was implemented, a basic evaluation experiment was conducted and trial calculations for the cost were performed. The corresponding results confirmed that the system can be realized at a lower cost than the bus location system using 3G/LTE.

A proposed Standalone BTS Network for Fire Bureaus in an entire province via Mixed-Mode Digital Radio, the whole system incorporates FDAS clients and Manual Call Points (MCPs) as sensor nodes connected wirelessly in star topology to their nearest Fire Protection Station that is acting as the Base Transceiver Station (BTS) of one or more municipalities and is networked using microwave digital radio to another neighboring BTS of another Fire Protection Station serving several other FDAS Clients and MCPs. The BTSs are connected in bus topology comprising several hops of microwave links. In this manner an alarm status in any client will be relayed to all member Fire Bureaus (BTS) that in turn could respond immediately.

Conventional bus transportation is of great value in urban transportation network, so it is important to master the regularity between bus lines and explore the optimization method to solve the problem of bus. Divided the degree of relation according to the overlapped stops between the two lines, and the relationship between the routes were divided into three types. The method of measuring the degree of relationship between lines and the modeling steps were given. According to the relationship between bus lines, a bus co-opetition network based on relationship degree was constructed. Using the social network analysis method, the network characteristics were found, the construction steps of the clustering method were given and the network was analyzed. The urban bus co-opetition network of Langfang City was built and the important lines were found by UCINET software. The study of the relationship between the bus lines can cluster the bus lines at the beginning of the bus network planning, which can also provide scientific basis for the operation and management of the buses.

This research investigates several problems associated with current multiprocessor interconnection networks, focusing primarily on general-purpose, shared-memory configurations. The project deals with all aspects of the interconnection, from the architectural level to the physical backplane. A multiple-bus based architecture is presented as an alternative to the limitations of current schemes. This dissertation will focus on the logical layer specification. The ActiveBus--a multiple, active bus--interconnection is proposed. Multiple buses increase the bandwidth as well as reliability of the interconnection while the active backplane shows a reduced and uniform capacitive load. A logical layer protocol was designed for each bus to work independently, to achieve fault tolerance. Each bus uses a word-serial approach to keep the total number of bus signal lines manageable. A dual clocking scheme is proposed. The faster clock is used for data transfer. The other clock, refered to as sync clock, is used for arbitration and handshaking. Absence of discontinuities on the bus coupled with a source-synchronous transfer protocol allows data to be streamed at a high rate, thus increasing the pin-efficiency of the bus. The data transmission rate is limited only by clock skew. In addition, the ActiveBus interface unit and the source synchronous protocol move the synchronization penalty from the shared bus to the private buffer in the unit. The protocol uses a new arbitration scheme, termed Previous Priority First. This hybrid control acquisition scheme combines collision detection and priority arbitration to minimize bus access time without requiring additional signal lines. Collision detection provides a quick access in an unsaturated system while priority arbitration guarantees the deterministic election of the master in a saturated system. The scheme also incorporates a fairness mode to minimize starvation and bus access delay in the system. The cache coherence scheme supports both copy-back and write-through policies to reduce the overhead. MOESI protocol with snoopy caches, being the most general, is followed. Message passing and synchronization primitives are provided within the bus protocol to support multiple processor systems. These primitives attempt to minimize the traffic generated by the spin locks or the memory hot spots.

To ensure reliability and availability of IEC 61850 based substation automation systems (SAS), High-availability Seamless Redundancy (HSR) or Parallel Redundancy Protocol (PRP) or both are used. This paper presents the analysis and comparison of the device connection capability and data recovery time performance for HSR and PRP networks. An IEC 61850 based substation with both HSR and PRP bays is designed and modelled using the OPNET. The device connection capabilities, e.g. the maximum number of devices that can be connected to a fixed bandwidth network, under various operating conditions are evaluated and studied. A comparison study between an HSR network and PRP network has also been carried out. The results show that the device connection capability of an HSR network can be reduced by as much as half as each packet is duplicated in the HSR network. The results also show that the Ethernet bandwidth utilization is decreased as the number of devices increases. The work may help utilities to determine the number of devices that can be connected into an HSR/PRP process bus network in order to ensure the network performance.

The Automotive Industry is on the verge of digital transformation. The race building fully connected and autonomous cars has begun and it will redefine the way we have been using transportation systems. The goal of connected cars is to provide personalized and safe driving, but connectivity is opening the doors for cyber-attacks. Control Area Network (CAN)-bus is a serial car bus network that connects Electronic Control Units (ECUs), sensors and actuators in a system or subsystem for control applications. Thousands of signals are recorded on the CAN-Bus which can give almost real-time information about the car, driver and the surroundings. This paper proposes a conceptual approach for intrusion detection and prevention systems (IDPSs) for connected cars and an overview of machine learning algorithms for anomaly detection as part of intrusion detection.

In this paper, we present a framework for building a hybrid network composed of Controller Area Network (CAN) bus and ISA100.11a industrial wireless network. The end-to-end delay of CAN-ISA100.11a hybrid network is evaluated. One scheme is proposed based on time slot configuration in ISA100.11a to ensure the prioritization hierarchy which is suitable for large packet size, namely priority assurance (PA). Moreover, a comparison between shared time slot and short time slot is evaluated to give insight on which one gives the best performance in CAN-ISA100.11a hybrid network. The delay of the proposed framework is further simulated under interference environment. We present a framework for building a hybrid network with CAN and ISA100.11a.We propose schemes to ensure prioritization and reduce end-to-end delay in hybrid network.The delay of the proposed schemes is evaluated by simulation under interference of IEEE 802.11.The delay bottleneck of the hybrid network lies on ISA100.11a network.Proposed schemes enable CAN-ISA100.11a hybrid network as an industrial network.