Broken Links Research Articles

Survey on Various DTN Routing Algorithms for Vehicular ADHOC Network (VANET)

Vehicle Adhoc Network (VANET) permits self-organized infrastructure. Link or Connectivity breakage or long delay (intermittent connection) is an important issue in the VANET which arises due to the dynamic topological changes. Mainly two algorithms Vehicle assisted Data Delivery (VADD) and Opportunistic routing algorithm supports for handling delay/disruption tolerant network (DTN). Intention of DTN is to create dynamic link between the sender and receiver vehicle in the case of link disruption or absence of path between two nodes and forwards the data using store carry and forward. VADD carry and forward the data as much as possible in disconnected network using intersection mode, straightway mode or destination mode. Opportunistic routing can deal the unreliable data and intermittent connectivity in VANET by considering the multiple nodes as a next hop forwarder instead of considering pre-selected single node to be the best forwarder. This paper gives the study about various opportunistic routing algorithms for handling delay/disruption tolerant network.

Q -Learning-Based High Credibility and Stability Routing Algorithm for Internet of Medical Things

With the outbreak of COVID-19, people’s demand for using the Internet of Medical Things (IoMT) for physical health monitoring has increased dramatically. The considerable amount of data requires stable, reliable, and real-time transmission, which has become an urgent problem to be solved. This paper constructs a health monitoring-enabled IoMT network which is composed of several users carrying wearable devices and a coordinator. One of the important problems for the proposed network is the unstable and inefficient transmission of data packets caused by node congestion and link breakage in the routing process. Based on these, we propose a Q -learning-based dynamic routing selection (QDRS) algorithm. First, a mathematical model of path optimization and a solution named Global Routing selection with high Credibility and Stability (GRCS) is proposed to select the optimal path globally. However, during the data transmission through the optimal path, the node and link status may change, causing packet loss or retransmission. This is a problem not considered by standard routing algorithms. Therefore, this paper proposes a local link dynamic adjustment scheme based on GRCS, using the Q -learning algorithm to select the optimal next-hop node for each intermediate forwarding node. If the selected node is not the same as the original path, the chosen node replaces the downstream node in the original path and so corrects the optimal path in time. This paper considers the congestion state, remaining energy, and mobility of the node when selecting the path and considers the network state changes during packet transmission, which is the most significant innovation of this paper. The simulation results show that compared with other similar algorithms, the proposed algorithm can significantly improve the packet forwarding rate without seriously affecting the network energy consumption and delay.

“Light Verse Can Be Serious” in the Songs of W. H. Auden

This study evaluates Auden’s “Twelve Songs” (1935-38), “Five Songs” (1948-53), “Two Don Quixote Lyrics” (1963) representing three different periods in the Auden canon in order to discuss the senses of anxiety and desperateness felt by the poetic personas. As the last major voice of Eliot generation, Auden poeticizes his process of problematic uniformity. In other words, he feels at home after the harassing motion of centring and decentring reflected in his early poems. The songs from the different periods of Auden demonstrate the unchangeable nature of hopelessness in his poems. However, the awareness of a broken link with various defining factors such as love and nature evolves into a humble acknowledgement in Auden’s later works. Thus, the selected poems share a similar attitude towards the basic arguments of love, loneliness, and bourgeoisie values besides the political implications on capitalism and religion. In conclusion, the analysis of “Twelve Songs,” “Five Songs” and “Two Don Quixote Lyrics” from his early, transition and later periods suggests that Auden’s poetry cannot be reduced into any formula and reflects his problematic perception of ‘peace’ as the poems waver between the songs of reunification and those of separation.

Kinetic Model of Moisture Diffusivity in Soursop Leaves (Annona muricata L.) by Convection Drying

Tea is considered to be a product that brings health benefits. The drying process showed high efficiency in processing this product. However, the process of moisture is not qdequately controlled, resulting in wasted energy in the drying process. The dynamics of the drying process of soursop leaves and the effect of temperature on the process speed were assessed in the present study. Five models (Newton, Henderson and Pabis, Page, Logarithmic, and Weibull) were used to determine the suitable drying dynamic at temperatures of 50°C, 55°C, 60°C and 65°C. The mechanism of the processing is based on the principle of dehumidification of the convection drying system with hot air, which caused the moisture inside the material to move outwards. The results showed that the drying temperature is directly proportional to the drying rate of the process, as the increase in drying temperaturefrom 50°C to 65°C produced the link breaking energy and heating thatleads to evaporation. Dehumidification rate depends on the temperature, change in Deff value as 1 x (RTa) -1 from from 9,264 95 × 10−9 m/s2 to 9.76485 × 10−9 m/s2. Page model with determination coefficient R2> 0.99 was found to be the most suitable model for experimental data.

Prediction Algorithm for Mobile Ad Hoc Network Connection Breaks

A Mobile Ad-Hoc Network (MANET) is a decentralized network of mobile node that are connected to an arbitrary topology via wireless connections. The breakdown of the connecting links between adjacent nodes will probably lead to the loss of the transferred data packets. In this research, we proposed an algorithm for link prediction (LP) to enhance the link break provision of the ad hoc on-demand remote protocol (AODV). The proposed algorithm is called the AODV Link Break Prediction (AODVLBP). The AODVLBP prevents link breaks by the use of a predictive measure of the changing signal. The AODVLBP was evaluated using the network simulator version 2.35 (NS2) and compared with the AODV Link prediction (AODVLP) and the AODV routing protocols. The simulation results reveal the effectiveness of AODVLBP in improving network performance in terms of average end-to-end delay, packet delivery ratio, packet overhead ratio, and packet drop-neighbour break.

Tunicate swarm Grey Wolf optimization for multi-path routing protocol in IoT assisted WSN networks

Internet of Things (IoTs) have become popular for connected people as well as objects for collecting and exchanging data based on embedded sensors. In IoT-assisted Wireless sensor Networks (WSN), the nodes are considered as the resource parameters in several ways, like computing resources, energy resources, and storage resources such that the robust multipath routing protocols are needed for maintaining long network lifetime and for achieving higher energy utilization. Hence, this paper presents the multipath routing protocol using the proposed optimization method, named Tunicate swarm Grey Wolf optimization (TSGWO) algorithm in the IoT assisted WSN network. By multipath routing protocol, the multipath is designed by multipath source node to several destinations. The multipath source node forwarding packet to multiple destinations simultaneously. At first, the nodes in IoT-assisted WSN network is simulated together and performs the cluster head selection using Fractional Gravitational Search algorithm (FGSA), and then the multipath routing process is done on the basis of proposed TSGWO in which the routing path is selected by considering the fitness parameters, like QoS parameters and trust factors. The QoS parameters include the delay, energy, link lifetime, as well as distance. The path with the minimum distance is selected as optimal path using fitness parameter. The proposed optimization algorithm effectively performs the multipath routing mechanism by integrating the parametric features from both the optimization algorithm. After that, the route maintenance process is carried out in the simulated IoT network to recover the link breakage based on DRINA. The proposed TSGWO outperformed other methods with maximal average Residual energy of 2.161 J, maximal link lifetime of 0.075 s, maximal PDR of 96.38%, and maximal throughput of429.49 Kbps.

Systems thinking-based risk assessment methods applied to sports performance: A comparison of STPA, EAST-BL, and Net-HARMS in the context of elite women's road cycling

There is increasing interest in applying systems Human Factors and Ergonomics (HFE) methods in sport. Risk assessment (RA) methods can be used identify risks which may impact the performance of individual athletes, teams, and overall sports systems; however, they have not yet been tested in sport. This study sets out to apply and compare three systems thinking-based RA methods in the context of elite sports performance and report on the frequency and types of the risks identified. The Systems-Theoretic Process Analysis (STPA) method, the Event Analysis of Systemic Teamwork Broken Links (EAST-BL) method, and the Networked Hazard Analysis and Risk Management System (Net-HARMS) method were applied to elite women's road cycling to identify all the credible risks that could degrade optimal team performance. The findings demonstrate that all three methods appear to provide useful results in a context other than safety, and that multiple risks threatening the performance of the cycling team were identified. Whilst the frequency and types of risks differed across the methods applied, there are additional theoretical, methodological, and practical implications to be considered prior to the selection and use of systems thinking-based RA approaches. Recommendations and directions for future HFE and sports science research are discussed.

Hierarchical Structure of Active Distribution Network in Power System

The active distribution network (ADN) is an integral component of the smart grid. The ADN improves reliability and resiliency in the power grid integrated with many distributed energy resources (DERs). This is possible that, during outage, the ADN can be isolated from the main grid and it can continue to operate in island mode with indeterminate broken links and scarce generation resources. With the active management of increasing DERs, the distribution network is changed to active distribution network from passive network. This paper reviews the characteristics and challenges of deployment of distributed power plants (DPPs) in hierarchical active distribution network

Efficient Vehicular Ad Hoc Network routing protocol using weighted clustering technique

The Vehicular Ad Hoc Network (VANET) technology is similar to the Mobile Ad Hoc Network (MANET) in operations. But due to high dynamics of vehicles as compare to mobile nodes in MANET, the routing protocols of MANET cannot be applicable for the VANET communications. The high mobility leads the challenges of frequent link breaks and hence poor Quality of Service (QOS) performance. The clustering based routing protocols solves this problems to some extent, however performing the efficient and lightweight clustering and cluster head (CH) selections is still the complex problem for VANETs. The main causes of such problems are related to key parameters such as mobility and geographical distances of vehicles while performing the clustering tasks. In given paper we present a lightweight CH selection and cluster formation by considering mobility and number of neighbors based on geographical distances of the vehicle key parameter at every clustering interval to achieve the stability in network. The superiority of this method is that it is simple and inclusively the part of regular routing operations. For each vehicle the weight is computed to become the CH using mobility and neighbors parameter, hence this method is called as Weight based Clustering for VANET (WCV) routing protocol. The simulation result proves the QOS efficient performance compared to the state-of-art protocols. The WCV protocols improved the overall throughput by 10% as compared to the recent clustering protocol and reduced the delay 7% approximately.

Broken external links on Stack Overflow

Stack Overflow hosts valuable programming-related knowledge with 11,926,354 links that reference to the third-party websites. The links that reference to the resources hosted outside the Stack Overflow websites extend the Stack Overflow knowledge base substantially. However, with the rapid development of programming-related knowledge, many resources hosted on the Internet are not available anymore. Based on our analysis of the Stack Overflow data that was released on Jun. 2, 2019, 14.2% of the links on Stack Overflow are broken links. The broken links on Stack Overflow can obstruct viewers from obtaining desired programming-related knowledge, and potentially damage the reputation of the Stack Overflow as viewers might regard the posts with broken links as obsolete. In this paper, we characterize the broken links on Stack Overflow. 65% of the broken links in our sampled questions are used to show examples, e.g., code examples. 70% of the broken links in our sampled answers are used to provide supporting information, e.g., explaining a certain concept and describing a step to solve a problem. Only 1.67% of the posts with broken links are highlighted as such by viewers in the posts' comments. Only 5.8% of the posts with broken links removed the broken links. Viewers cannot fully rely on the vote scores to detect broken links, as broken links are common across posts with different vote scores. The websites that host resources that can be maintained by their users are referenced by broken links the most on Stack Overflow -- a prominent example of such websites is GitHub. The posts and comments related to the web technologies, i.e., JavaScript, HTML, CSS, and jQuery, are associated with more broken links. Based on our findings, we shed lights for future directions and provide recommendations for practitioners and researchers.

Swarm Relays: Distributed Self-Healing Ground-and-Air Connectivity Chains

The coordination of robot swarms - large decentralized teams of robots - generally relies on robust and efficient inter-robot communication. Maintaining communication between robots is particularly challenging in field deployments. Unstructured environments, limited computational resources, low bandwidth, and robot failures all contribute to the complexity of connectivity maintenance. In this paper, we propose a novel lightweight algorithm to navigate a group of robots in complex environments while maintaining connectivity by building a chain of robots. The algorithm is robust to single robot failures and can heal broken communication links. The algorithm works in 3D environments: when a region is unreachable by wheeled robots, the chain is extended with flying robots. We test the performance of the algorithm using up to 100 robots in a physics-based simulator with three mazes and different robot failure scenarios. We then validate the algorithm with physical platforms: 7 wheeled robots and 6 flying ones, in homogeneous and heterogeneous scenarios.

Penerapan Algoritma Semut pada Protokol Routing AOMDV untuk Optimasi Pencarian Rute di Jaringan VANET

VANET is a wireless network that is a derivative of the MANET network. VANET network is one network that can be used to communicate between one vehicle and another vehicle. With the existence of the VANET network, it is expected to be able to improve the safety of drivers on the highway. One of the uses of the AOMDV routing protocol is that it can be used to help the performance of the VANET network, the AOMDV routing protocol. AOMDV routing protocol in conducting route search there are two working mechanisms namely route discovery and route maintenance. The route selection process in the AOMDV routing protocol is to consider the number of hops contained in the AOMDV routing protocol, so that the possibility of a broken link, therefore the need for the application of the method in conducting this research. The ant algorithm is one method that can optimize the process of finding a route in the AOMDV routing protocol. The ant algorithm in carrying out the route search is by calculating the distance between nodes. In the ant algorithm, the route selection is based on the most powerful pheromones, so the route chosen is no longer based on the number of hops. From the results of trials that have been carried out on the AOMDV routing protocol using the ant algorithm can improve the performance of the test throughput parameters of 9.7649 Kbps and the performance of the Packet Delivery Ratio of 11.2838%. Whereas the average end to end delay parameter can reduce the delay by 13.3093ms

A Medium-Term Disruption Tolerant SDN for Wireless TCP/IP Networks

A novel framework, Medium-Term Disruption Tolerant Software Defined Network (MDT-SDN), is proposed to handle medium-term disruptions of the order 10 seconds to 6 minutes. Such medium-term disruptions are crucial for the next generation wireless networks that use TCP/IP protocol stack, where the existing disruption tolerant approaches may under-perform due to resource constraints. MDT-SDN enables network control with an additional STORE action which exploits the nodes’ memory for buffering packets within the TCP/IP stack during link disruptions and forwards them as the links become alive. First, we model the network with medium-term disruptions using temporal graphs and design an Earliest Arrival Path with Minimal Storage Time (EAPMST) controller algorithm to demonstrate the MDT-SDN framework. The framework is realized in a software defined wireless mesh network testbed, using in-band control, involving mobile nodes with three mobility models: ( ${i}$ ) stationary nodes, ( ii ) group mobility, and ( iii ) random mobility. Experimental results with four application protocols justify the efficacy of MDT-SDN in providing storage control and additional performance benefits. MDT-SDN along with EAPMST improves the throughput beyond 25% with random mobility model and is capable of carrying packets and maintaining sessions during medium-term disruptions using the existing TCP/IP stack. The use of EAPMST reduces packets’ buffering time by 24.45% in group mobility while the buffering time increases in random mobility by 5.82%. However, EAPMST significantly reduces the buffer occupancy by 60.28% and 44.49% for group and random mobility, respectively.

Влияние новых производных бензотиазола на показатели когнитивного статуса лабораторных животных

Исследовано влияние новых сукцинат- и ацетилцистеинат производных бензотиазола, обладающих актопротекторным действием, на структуру индивидуального поведения мышей в обычных условиях и на фоне истощающих физических нагрузок. Установлено, что присутствие в молекуле вещества фрагмента ацетилцистеина способствует увеличению объема паттернов «обнюхивание», «перемещение», «движение на месте» на 25 – 228 % (p < 0,05) в сравнении с контролем как в обычных условиях, так и при воздействии физических нагрузок. Аналогичным эффектом в указанных условиях опыта обладал и препарат сравнения этилтиобензимидазол. Такие изменения в поведении мышей могут указывать на повышение тонуса двигательных центров, что можно рассматривать в качестве одного из ключевых моментов в актопротекторном действии соединений. Сукцинат не проявляет подобного влияния, более того, в структуре производных аминобензотиазола и метиламиногидроксибензотиазола проявляется ярко выраженное депримирующее действие на работу нервных центров вплоть до разрушения нормального поведения в условиях действия истощающих физических нагрузок. На это указывает не только снижение доли паттернов «обнюхивание», «перемещение» и «норка» на 21 – 85 % (p < 0,05) в сравнении с контролем, но и нарушенные связи между ними.

Combining Usability Testing with In-Depth Interview for Online Credit Hour Website Evaluation

The Online Credits Hour (KRS) application is one of the existing systems at the University of Muhammadiyah Magelang where the academic community, including lecturers, students, and education staff, produces a large amount of student academic data. Evaluation is necessary to find out whether the system runs well. This study is an effort to evaluate the system employing a usability test consisting of five indicators, namely learning ability, memory, efficiency, errors, and satisfaction. The five indicators materialized in the form of questionnaires to online KRS users. The survey involved 118 respondents. The method of study includes validity and reliability tests. The validity test employs a correlation test. The reliability test uses a simple linear regression analysis test and the comparison uses the significance value Alpha equals 0.05. The validity test for all five indicators results in value above 0.05. The reliability test of all the answers in the questionnaire has a Cronbach's Alpha value of 0.93, which suggests that the whole has correspondence. The evaluation results show that the KRS Online application has the highest value in the memorability indicator at 3.97, indicating that the KRS Online application is easily accessible with easy procedures to obtain data. The lowest value is on the error indicator at a level of 3, which means that the KRS Online website shows many errors, such as a broken link or poor navigation.

Performance of Mobile Ad-Hoc Network

Recent the researchers very interested to work temporary infrastructure less network called MANET (Mobile Ad-hoc Networks), this one decentralized network with communicated each other via intermediates nodes. In this temporary network based routing is major issue is energy, security and packet drop because of varying network topology due to changing link breakage and node join or leave and mobility of network (source mobility, sink mobility and event mobility with varies three different routing protocols such as table driven and on-demand. In this survey paper discussed performance of various protocols, on-demand such as AODV (ad-hoc on-demand distance vector) and DSR (dynamic source routing) and table driven DSDV (destination sequence distance vector) routing protocols with varying number of nodes and data rate with different environment using various parameters like packet delivery ration, delay and routing congestion using NS2 (network simulator 2, simulation results of packet delivery ratio and congestion best for DSR and AODV then DSDV, results of simulator AODV PDR slightly high then DSR, AODV delay and congestion slightly low then DSR, DSR congestion slightly low then AODV.

Transmission Efficiency of Licklider Transmission Protocol (LTP) and Bundle Protocol (BP) in DTN Architecture

From Near-Earth orbit (NEO) to Earth-Sun Lagrangian points will continue to be a majority of Near Earth missions ranging from Near-Earth orbit (NEO) to Earth-Sun Lagrangian points will continue to be a majority of future space missions. A few works have been done with delay/disruption tolerant networking (DTN) technology for Near-Earth orbit (NEO)-space center and deep space communications and provided feasibility for its adoption in NEO-space and deep space missions. [1] However, no much work has been done to fully evaluate the transmission efficiency of DTN in such an environment, especially in the presence of long link disruption, data corruption and lost rate, and link asymmetry. In this paper, we present an experimental performance evaluation of DTN architecture and protocol stack, with Licklider transmission protocol (LTP) serving as a convergence layer adapter (CLA) underneath bundle protocol (BP), in typical NEO-satellite system and deep space communication infrastructures accompanied by a very long link delay, various packet corruption and lost rates, and channel rate symmetry and asymmetry. In addition, we present an experimental research of the transmission efficiency of DTN custody transfer with long link delay. The experiment was conducted by performing realistic file transfers over a virtual server-based test-bed.

LE-OLSR protocol performance evaluation in various energy conditionsof mobile Ad-hoc and sensor wireless networks

<p>A mobile Ad hoc and sensor wireless network commonly includes various mobile devices and sensors with limited resources. In such network, energy constraint and link stability are the most critical parameters to take into consideration when deploying routing mechanisms, to assure reliable communication between nodes.These requirements are due to the network scalability and the absence of a fixed infrastructure, which may cause a rapid depletion of the nodes batteries and leads onto network link breakages. LE-OLSR (Lifetime Enhancement - Optimized Link State Protocol) is a variant of the existing OLSR. This latter is widely used as routing protocol for mobile ad-hoc and wireless sensor networks. LE-OLSR implements a new load balancing algorithm; it takes into account energy constraints of a node when selecting routers, responsible for forwarding data packets over the entire network. The aim of our work is to study and simulate the LE-OLSR protocol behavior in realistic mobile environments, including scenarios with various residual energy constraints schemes. The performed simulations had shown that LE-OLSR performances decrease compared to the case of ideal mobile network. Nevertheless, LE-OLSR had shown persistence and fair results in the realistic environment.The obtained results show that LE-OLSR protocol is an adequate and a prime solution for dense mobile ad hoc networks.</p>

Estimation of the possibilities of the combined synchronization system with open-link to minimize the dispersion of the phase error when tracking the carrier frequency under the conditions of the influence of additive noise

The object of the article is the process of evaluating the possibilities of a combined synchronization system with open (compensating) connection to minimize the phase error variance under the influence of additive Gaussian noise.The issue of improving the quality of the phase synchronization system is a constant topical scientific task and in a number of studies is solved by including the method of developing mathematical models and creating on their basis the appropriate optimal schemes for building these systems. The final stage of development and implementation of such mathematical models in technical solutions and synchronization schemes based on them is the assessment of the limit possibilities of these schemes to minimize the variance of the phase error in different types of noiseThe paper evaluates the possibilities of a combined synchronization system with open (compensating) connection to minimize the phase error dispersion under the influence of additive Gaussian noise by selecting the parameters of the components of the circuit of this connection.In order to evaluate the work, mathematical dependencies have been developed and refined, which allow to determine the variance of the phase error under the influence of additive Gaussian noise and the corresponding algorithm for its determination is presented.The evaluation results presented in the work showed that the value of the error variance for the combined synchronization system is much smaller than for the closed synchronization system with any choice of the parameters of the latter. The effect of reducing the phase error variance by introducing a broken link at a given level of influence depends on the noise signal level and the phase modulation index of the input signal. When using as a simple broken link a frequency discriminator included in the circuit of the combined synchronization system in parallel, the minimum dispersion of the phase error when the noise level rises to a certain critical limit is limited and this broken link loses its effectiveness.

Suffering in silence: How COVID-19 school closures inhibit the reporting of child maltreatment

To combat the spread of COVID-19, many primary and secondary schools in the United States canceled classes and moved instruction online. This study examines an unexplored consequence of COVID-19 school closures: the broken link between child maltreatment victims and the number one source of reported maltreatment allegations—school personnel. Using current, county-level data from Florida, we estimate a counterfactual distribution of child maltreatment allegations for March and April 2020, the first two months in which Florida schools closed. While one would expect the financial, mental, and physical stress due to COVID-19 to result in additional child maltreatment cases, we find that the actual number of reported allegations was approximately 15,000 lower (27%) than expected for these two months. We leverage a detailed dataset of school district staffing and spending to show that the observed decline in allegations was largely driven by school closures. Finally, we discuss policy implications of our findings for the debate surrounding school reopenings and suggest a number of responses that may mitigate this hidden cost of school closures.