Redundant Paths Research Articles

Research on Game Strategy of Crossing Desert

This paper analyzes the players in the game of "crossing the desert", and puts forward the optimal customs clearance strategy to help the game players reach the destination within the specified time under the condition that the remaining funds are retained as much as possible. Firstly, the redundant paths are eliminated and the complete subgraph of the game map is drawn to improve the speed of computer optimization. Then, the multiple rules in the game are transformed into the constraints in the planning model, such as load constraint, remaining fund constraint, resource margin constraint and so on. By solving the model based on adjacency matrix and mixed integer programming, the rationality of the optimization strategy is verified by an example. The waiting model is used to decompose the number of players and consider different space and time to maximize the revenue of a mine as much as possible, while reducing the basic consumption of latecomers in a certain area and the consumption of resources purchased in the same village.

Redesign Integrated Control System GTG and HRSG to Reduce Loss of Electrical Production at Combined Cycle Power Plant Muara Karang

Combined Cycle Power Plant (CCPP) Block 1 Muara Karang control system had performance degradation since 2016-2017. Performance degradation comes from the complexity of the design architectures that are serially configured which can cause loss of electrical production. The Re-Design Method is able to simplify the architecture design by replacing hardware devices into modbus-based TCP-IP software that is compatible with the communication technology between GTG and HRSG and has a redundant path that can increase reliability. Based on the Muara Karang PLTGU Block 1 disturbance report data, redesign is able to increase reliability and better financial aspect. It shows that before the redesign there were 9 disruptions, while after the redesign there were no failures and Total saving opportunity loss of electrical production is Rp 10,792,782,094.30. This value is obtained from the unit repair time from operation failure and electricity sales price. On the corporate side, Re-Design can be applied to other generating units that have differences in technology based on open protocol.

Automated test generation for IEC 61131-3 ST programs via dynamic symbolic execution

Programmable logic controllers (PLCs) are essentially domain-specific computers that are widely used in the industrial field. These industrial devices are usually required to be of high reliability, and program bugs can lead to catastrophes. However, there are few automated testing tools for PLC programs. This paper proposes a framework, named STAutoTester, for automatically generating test cases for IEC 61131-3 Structured Text (ST) programs. It adopts Dynamic Symbol Execution (DSE) combined with redundant path pruning to efficiently perform PLC multi-cycle test data generation under different coverage criteria. We have evaluated STAutoTester on 21 programs. The experimental results show that STAutoTester can effectively handle these programs. Compared to S Y M PLC , a previous symbolic execution based tool for automatically testing PLC software, we achieved comparable statement coverage with much fewer test cases. Besides, we have achieved greater branch coverage and stricter MC/DC coverage, which were not implemented by S Y M PLC .

Assessment of playa wetland network connectivity for amphibians of the south-central Great Plains (USA) using graph-theoretical, least-cost path, and landscape resistance modelling

Land-cover changes are likely affecting structural and functional connectivity for wetland-associated wildlife among the > 80,000 playa of the Great Plains (USA). We investigated how patterns of land cover from 2008 to 2016 affected structural and functional connectivity among playas under biologically feasible scenarios and a range of vagilities for amphibians. We compared graph-theoretical, least-cost path (LCP), and landscape resistance models. Using land-cover and irrigation data and literature-based estimates of species-specific dispersal, we developed three alternative scenarios with resistance values that differed by land-cover type. Sensitivity analysis examined effects of altering the numeric range of values within models. From a structural perspective, the playa network was highly fragmented, with coalescence distances greater than amphibian dispersal capabilities (> 15 km). The network was insensitive to assigning different resistance values to different land-cover types: 81% of LCP locations overlapped with at least one other modeled scenario, and 57% of LCPs overlapped among all three scenarios. Our findings partially support previous graph-based assessments of playa structural connectivity that indicated high levels of path redundancy within this ecological network. However, although there was extensive path overlap among scenarios, many modelled linkages were at distances well beyond the individual lifetime dispersal maxima for regional amphibians. Thus, functional connectivity would be achieved in this landscape only by spanning scales from daily movements to inter-generational dispersal.

Selenium bioavailability in soil-wheat system and its dominant influential factors: A field study in Shaanxi province, China

Selenium (Se) content of crops depends on the local soil Se content and/or its bioavailability, and identifying the influence factors of soil Se bioavailability is a significant basis for adopting targeted agronomic measures to improve the Se nutritional status of humans. In this study, the main wheat–producing region in Shaanxi province with similar parent material and climate conditions was selected as the study area. The total Se contents of 602 soil samples and their corresponding wheat grains were determined, and the distribution characteristics of soil Se bioavailability and its dominant influential factors were investigated. Results showed that the total Se content ranged from 0.02 mg/kg to 1.67 mg/kg (average of 0.25 ± 0.25 mg/kg) in soil, which was lower than that content in China (0.29 mg/kg). The Se content of wheat grain was 0.001–1.50 mg/kg (average of 0.11 ± 0.19 mg/kg). The distribution trend of the Se content in wheat grains was different from that of the total soil Se, but it was consistent with the distribution of soil bioavailable Se content. The bioavailable Se accounted for 11.1% of the total soil Se. This could be attributed to relatively high soil Se bioavailability of the study area belonging to alkaline soil (with a pH of approximately 8). Both redundancy analysis and path analysis revealed that soil pH and organic matter were the dominant influential factors of soil Se bioavailability in Shaanxi wheat–producing area, and the soil Se bioavailability increased with these two parameters raising. On this basis, a prediction model was established to predict the Se content in wheat grain. The results show that the various agronomic measures could be used to produce Se-enriched wheat by regulating the soil pH and the organic matter content in Se biofortification practice.

An intelligent fuzzy-based routing scheme for software-defined vehicular networks

Due to the lack of fully considering dynamic traffic information, in Vehicular Ad-hoc Networks (VANETs), existing routing schemes are easily stuck in local optimum, path redundancy, and congestion problems. By combining Software Defined Network (SDN) with VANET, the emerging Software Defined Vehicular Network (SDVN) can provide a global perspective of the traffic network to bridge the gap. In this paper, we introduce an intelligent fuzzy-based routing scheme for urban SDVN. First, a large urban area is divided into multiple sub-areas, in which each area is centered on an intersection. Second, the central controller maintains a routing table that records the priorities of packets be forwarded from an area to another, and all values in the routing table are initialized using Fuzzy Logic. Finally, we propose a hierarchical greedy routing with link stability (GLS) to calculate the routing path with the highest link stability according to the routing table. Meanwhile, considering the dynamic nature of vehicles in an area, Reinforcement Learning is employed to update the routing table during the routing process. Simulation results show that the proposed routing scheme achieved a significant improvement in performance over its counterparts.

A fault-tolerant architecture for internet-of-things based on software-defined networks

One of the most critical challenges of the Internet of Things (IoT) is to provide real-time services. Therefore, to provide a secure, efficient, and stable communication platform in the Internet of Things, emerging architectures such as software-defined networks (SDN) being significant. This paper proposes a comprehensive SDN based fault-tolerant architecture in IoT environments. In the proposed scheme, a mathematical model called Shared Risk Link Group (SRLG) calculates redundant paths as the main and backup non-overlapping paths between network equipment. In addition to the fault tolerance (FT) discussion in the proposed scheme, service quality is considered in the proposed scheme. Putting the percentage of link usage and the rate of link delay in calculating link costs makes it possible to calculate two completely non-overlapping paths. The end-to-end delay and the degree of link congestion are minimal. We compare our proposed scheme with two policies for building routes from source to destination. The simulation results indicate that, while reducing the error recovery time, the proposed method leads to improved services quality parameters such as packet loss, delay, and packet jitter. The results show that in case of a link failure in the network, the recovery time in large scenarios is a maximum of 16 ms, which improved by 20%, compared to the disjoint paths (DP) method. Our Approach can decrease packet loss by approximately 30% compared to the Dijkstra’s algorithm and roughly 24% compared to the DP method. Also, SLRG reduces latency by approximately 36% compared to the Dijkstra’s algorithm and roughly 19% compared to the DP method. Last, the proposed scheme reduces Jitter by approximately 49% compared to the Dijkstra’s algorithm, and roughly 26% compared to the DP method.

Dynamic Network Path Provisioning and Selection for the Detection and Mitigation of Data Tampering Attacks in Networked Control Systems

Networked control systems can help build cost-effective and flexible industrial systems. A system that can function while being immune to cyberattacks is necessary. A method called fixed redundant path selection (FRPS) has been proposed to detect and mitigate data tampering attacks in a networked motion control system. This system contains redundant forward network paths from the controller to the motor sides to detect the attacked path by comparing the values that are received through respective paths. Then, a path selector on the motor side chooses a value on the path that is not attacked based on the majority decision. Increasing the number of redundant paths improves the detection performance of simultaneous attacks against multiple paths. However, it also increases the amount of traffic because the same data are transmitted to all of the redundant paths. This study proposes a dynamic redundant path selection (DRPS) method to balance the detection performance and the amount of traffic. The proposed method initially applies three redundant paths and changes the number of redundant paths to five only when the path selector detects a difference among the received values for the three paths. The experiments confirm that the proposed DRPS outperforms the conventional FRPS. The former can detect and mitigate the data tampering attacks while reducing the number of network paths during tampering detection when the system is exposed to simultaneous attacks against up to two of the redundant paths.

Fault Tolerant List Scheduler for Time-Triggered Communication in Time-Sensitive Networks

The performance and dependability of modern mission-critical systems significantly depends on the communication infrastructure. In this context, the Time-Sensitive Networking (TSN) task group addressed different requirements of cyber-physical systems such as timing and reliability constraints. TSN provides real-time capabilities through sharing a global time reference and employing transmission schedule tables called Gate Control Lists (GCL). On the other hand, TSN masks faulty behaviors within a system through a technique called Frame Replication and Elimination for Reliability (FRER). FRER fulfills the safety requirements of mission-critical systems by message replication and transmission of message replicas over redundant paths. The scheduling problem for the GCL synthesis is NP-complete. For simplification of the scheduling process, several state-of-the-art solutions provide schedulers for fault-free networks. However, this assumption is very optimistic and in practice networks experience different faulty-behaviors over time. This paper extends our heuristic TSN scheduler which was developed for fault-free TSN systems to support the FRER mechanism. Our fault-tolerant TSN scheduler focuses on enhancing the reliability of a mission-critical system while meeting the deadlines of time-critical jobs. To achieve this goal, we introduce a novel reliability analysis approach for a mission-critical system with a TSN communication infrastructure. This approach models and evaluates the reliability of a system based on the reliability of message transmissions between safety-critical jobs. The reliability of message transmissions is computed based on the reliability of the network components that form the forwarding paths. Thereby, our reliability model enables the system designers to plan networks more optimally.

Retrofitted IoT Based Communication Network with Hot Standby Router Protocol and Advanced Features for Smart Buildings

The advent of renewable energy sources brings the concept of building power systems, which are located at the load-centres/buildings. Further, the concept of smart building in the modern energy era increases operational efficiency, safety, and consumer comfort, where, all its operations are monitored and controlled by central monitoring and control unit (CMCU). However, for reliable communication between the components of smart building and the CMCU, a well-established network is essential. This network shall provide advanced features such as user alerts, usage details, remote control options, link failure handling, security, etc. However, the traditional IoT network can’t provide all these features and poses a challenge to use it for smart buildings due to inadequate technology to meet the unremitting user requirements. In this context, this paper proposes a retrofitted IoT based communication network with Hot Standby Router Protocol (HSRP) for remote monitoring and control of smart building devices. Besides, this proposed network possess Adaptive Security Appliance (ASA) firewall, Message Queuing Telemetry Transport (MQTT) protocol, and email alert to facilitate all the advanced features. The HSRP handles the link failures by providing a redundant path, thereby ensures reliable communication in the network. The ASA firewall provides intrusion prevention (blocking unauthorized packets). The MQTT enables the broker for broadcasting messages to all the subscribers of a particular topic. Similarly, the email alert provides communication between different users in the building. Altogether, this proposed communication network establishes a reliable monitoring and control facility in smart buildings, which is simulated and verified using Cisco Packet Tracer 7.3.1.

Dynamic Response Analysis of Composite Tether Structure to Airborne Wind Energy System under Impulsive Load

The tether structure plays the role of transferring the traction force of an airborne wind energy system (AWES) to the fixed or mobile ground system with less motion and maintains the flying airborne system as a critical component. The implementation of a geometrically tailored tether design in an AWES could avoid unwanted snap-through failure, which can be take place in a conventional tether structure under impulsive loading. This concept relies on the redundant load path of the composite structure composed of tailored length and strength. In this study, the dynamic response of this composite tether structure to airborne wind energy systems, such as a kite wind power system, was analytically investigated. Also, for very long tether applications, an approximate model of the tether response was developed, which resulted in a dramatic reduction of computational efforts while preserving the accuracy quite well compared to the exact solution.

Forest management practices of Pinus tabulaeformis plantations alter soil organic carbon stability by adjusting microbial characteristics on the Loess Plateau of China

Sustainable management practices can enhance the capacity and potential for soil carbon (C) sequestration, significantly contributing towards mitigating regional climate change. Here, we investigated how the microbial characteristics of a Pinus tabulaeformis plantation responded to different management practices to identify the role of microbial characteristics in influencing the stability of soil organic carbon (SOC). We chose a Pinus tabulaeformis plantation on the Loess Plateau where forest management practices had been conducted since 1999. Five forest management practices were implemented: two at the forest level (P. tabulaeformis with and without ground litter), and three using different vegetation restoration approaches after clear-cutting (P. tabulaeformis seedlings, abandoned grassland, and natural shrub regeneration). Microbial biomass, soil respiration, microbial community structure, microbial metabolic function, and soil oxidizable organic carbon (OC) fractions were evaluated. Forest management practices changed SOC stability by adjusting the microbial characteristics (e.g. soil microbial community diversity and microbial metabolic function diversity). The result of path analysis was that the direct path coefficient of microbial biomass on soil oxidizable OC fractions was the largest, which was 1.499. Path analysis and redundancy analysis showed that microbial biomass had the largest direct influence on soil oxidizable OC fractions. Compared with other forest management practices, natural shrub regeneration increased the nonlabile carbon fraction by increasing soil microbial characteristics, and contributed the most towards stabilizing SOC, which enhanced the stability of the soil ecosystem on the plateau. In conclusion, microbial biomass was the biggest influence factor of SOC stability. In contrast, the stability of SOC may be most stable in the area of natural shrub regeneration.

A vulnerability-based vehicle routing approach for solving capacitated arc routing problem in urban snow plowing operations.

Vehicle drivers usually perceive a higher risk when driving on snow covered roads. The city cleaning efficiency would directly influence the risk and mitigation of wintertime events, especially for snow covered roads. Under the risk-informed approach background, more attention is paid to the capacitated arc routing problem (CARP) of urban snow plowing operations. Current algorithms mainly relies on the topology of road network without considering snow covered pavement's negative effect on road capacity and traffic flow. This paper proposes a vulnerability-based parallel heuristic algorithms applied for the CARP by implementing risk-informed approach. First, a method is proposed to set service priorities based on the vulnerability evaluation by considering the added cost of travel demands. Second, a sub-process path-scanning approach is developed to avoid redundant path scans. Then verification and comparison between this newly proposed constructive heuristic and existing algorithms of whole-process path-scanning and sequential processing are conducted. Results show that the sub-process path-scanning approach obviously costs less service completion time than the existing algorithms for solving the CARP. However, this improved algorithm would also cause an increase of deadhead time upon dispatch. The balance between service completion time and deadhead time for more routing problems would be discussed in the near future.

A Multifunctional Integrated Circuit Router for Body Area Network Wearable Systems

A multifunctional router IC to be included in the nodes of a wearable body sensor network is described and evaluated. The router targets different application scenarios, especially those including tens of sensors, embedded into textile materials and with high data-rate communication demands. The router IC supports two different functionality sets, one for sensor nodes and another for the base node, both based on the same circuit module. The nodes are connected to each other by means of woven thick conductive yarns forming a mesh topology with the base node at the center. From the standpoint of the network, each sensor node is a four port router capable of handling packets from destination nodes to the base node, with sufficient redundant paths. The adopted hybrid circuit and packet switching scheme significantly improve network performance in terms of end-to-end delay, throughput and power consumption. The IC also implements a highly precise, sub-microsecond one-way time synchronization protocol which is used for time stamping the acquired data. The communication module was implemented in a 4-metal, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.35~\mu \text{m}$ </tex-math></inline-formula> CMOS technology. The maximum data rate of the system is 35 Mbps while supporting up to 250 sensors, which exceeds current BAN applications scenarios.

An improved medial axis path generation algorithm for selective laser melting

PurposeThe principle of the medial axis calculation is complicated and difficult to implement. Moreover, the accuracy is not high. Then, as the generated path has an endpoint at the boundary of the polygon, burrs may appear on the surface of the molded piece. This paper aims to improve the warpage deformation of SLM molded parts and the surface quality of molded parts, an improved mid-axis path generation algorithm is proposed.Design/methodology/approachFirst, the center point is calculated by the seed point growth method based on the distance transform, and the obtained medial axis has high precision and is suitable for simple polygons and complex polygons. Then, based on the extracted medial axis, a preliminary path is generated, the path is trimmed with MATLAB to remove the redundant path. Finally, a scan along the contour of the polygon is performed to improve the surface quality of the molded part.FindingsThe algorithm reduces the internal stress generated during the molding process by continuously changing the scanning direction of the path along the boundary curve of the scanning area, thereby reducing the amount of warpage of the molded part. The result of extraction has a higher precision and wider scope of application than other methods to extract central axis, such as the Voronoi diagram-based method. The path is trimmed to remove redundant paths and the polygon boundaries are scanned to further improve the surface quality of the molded part. The results show that warpage deformation of the proposed algorithm is significantly smaller than the other two methods, thus the forming precision is higher.Originality/valueAn improved medial axis path generation algorithm is proposed in this paper. The proposed method is applied to improve warpage deformation occurring in the SLM process. Seed point growth of distance transformation is used to extracted central axis. The result of extraction has a higher precision and wider scope of application than other methods to extract central axis, such as the Voronoi diagram-based method.

Autonomous Tracking Using a Swarm of UAVs: A Constrained Multi-Agent Reinforcement Learning Approach

In this paper, we aim to design an autonomous tracking system for a swarm of unmanned aerial vehicles (UAVs) to localize a radio frequency (RF) mobile target. In the system, UAVs equipped with omnidirectional received signal strength (RSS) sensors can cooperatively search the target with a specified tracking accuracy. To achieve fast localization and tracking in the highly dynamic channel environment (e.g., time-varying transmit power and intermittent signal), we formulate a flight decision problem as a constrained Markov decision process (CMDP) with the main objective of avoiding redundant UAV flight path. Then, we propose an enhanced multi-agent reinforcement learning to coordinate multiple UAVs performing real-time target tracking. The core of the proposed scheme is a feedback control system that takes into account the uncertainty of the channel estimate. We prove that the proposed algorithm can converge to the optimal decision. Our simulation results show that the proposed scheme outperforms standard Q-learning and multi-agent Q-learning algorithms in terms of searching time and successful localization probability.

Agent-Based Multipath Management for Supporting Sink Mobility in Wireless Sensor Networks

In wireless sensor networks, sink mobility support is one of the essential functionalities in many applications. With continuous advancement, future applications will require not only sink mobility support but also high-performance data delivery service. Multipath routing is one of the promising technologies for improving data delivery performance by collaboratively using alternative or redundant multiple routing paths. However, existing multipath routing protocols had not dealt with sink mobility. As a result, they lead to bad performance in terms of energy efficiency due to the end-to-end path reconstruction. Consequently, a novel multipath management scheme is required thereby supporting sink mobility without performance degradation. In this paper, we propose a multipath management scheme for supporting sink mobility. The proposed scheme dynamically constructs multipath along the moving path of a sink. In addition, the proposed scheme provides the path shortening schemes according to the sink’s movement for reducing energy consumption. Our simulation results show that the proposed scheme is superior to existing path management schemes in terms of reliability and energy efficiency.

An adaptive packets hopping mechanism for transmission line monitoring systems with a long chain topology

To achieve the goals of efficient and safe operation of smart grids, a remote monitoring system for extra-high voltage (EHV) transmission line is required. In Taiwan, most of the towers of EHV transmission systems built by Taiwan Power Company (TPC) are located in remote areas and their line topology resembles a long chain. Therefore, the monitoring network designed for the EHV transmission lines cannot easily gain access to energy sources to power its communication nodes and may become fragmented due to any node failure. In view of the challenge, this study proposes a customized routing scheme for EHV transmission line monitoring, named transmission coverage adjustable multi-hop algorithm (TCAMA). TCAMA not only controls transmission power but also performs route selection to minimize power consumption. This algorithm also creates multiple redundant paths to meet the communication performance requirements. To verify the effectiveness of TCAMA, an Internet of Things-based monitoring system has adopted the proposed TCAMA to monitor an actual TPC EHV transmission system to examine its communication network performance. First, a gateway was developed, and a point-to-point transmission experiment was conducted to evaluate the transmission performance of the gateway with different transmission power and distances. Second, the results of the point-to-point experiment served as the transmission parameters in the network simulation, and 150 simulations were conducted. Then, the simulation results were analyzed to determine whether the data packet transmission performance met the communication requirements of a smart grid. Third, the performance of TCAMA was further examined using the distribution and topology of critical EHV transmission lines in Taiwan. Based on the field test results, TCAMA can prevent packet storms and can perform customized tasks using empirical measurements. In addition, TCAMA is capable of achieving 100% packet delivery while maintaining end-to-end communication delay much less than 2000 ms. The delay and energy consumption during the network transmission can also be reduced when TCAMA is employed.

Research on the Effectiveness Design of Information System Software Test Case Based on Clustering Algorithms

With the rapid development of software industry, the scale of software becomes larger and larger, and the complexity of software becomes higher and higher. The test coverage criterion traverses to get the corresponding test path and deletes the redundant path according to the constraints, then analyses and eliminates the contradictions in each test scenario to get the consistent requirement scenario, and finally generates the test case set of interlocking software. Test cases are the basis of test execution. Effective writing of test cases plays an important role in the whole testing process of information system. There are constraints (such as dependencies and mutual exclusions) between input items or parameter values, and the constraints certainly exist. From the initial frequent pattern mining to closed pattern mining, maximum pattern mining, incremental mining, topic interest measurement, privacy protection, data flow and other types of data mining association rules.

Resilience and technological diversity in smart homes

This article introduces our abstract modeling strategy to represent the general features and topology of the kinds of integrated and technologically diverse networks that feature in IoT systems. We begin with smart home networks. We generate instances of our model and analyze their graph-theoretic properties with an emphasis on the resilience of critical services and connections to the Global Internet. In addition to considering the network connectivity graph of nodes and links in the model, we explain our technology interdependence graph techniques. Technology interdependence graphs allow us to illuminate critical interactions in multi-technology systems such as smart homes. Using relatively simple examples we show how our approach permits the exploration of the resilience properties of various instances of smart systems involving complex technological interdependency. We describe a practical way of approaching the graphs of systems with a wide variety of integrated technologies and we discuss properties such as connectedness and other metrics. This approach can serve as the basis for tackling the challenge of designing resilient IoT-based smart-cities from the point of view of network topologies. We also study smart home resilience through path redundancy and heterogeneity of network technologies with graph centrality metrics.