Biblio

Both the data science and scientific computing communities are embracing GPU acceleration for their most demanding workloads. For scientific computing applications, the massive volume of code and diversity of hardware platforms at supercomputing centers has motivated a strong effort toward performance portability. This property of a program, denoting its ability to perform well on multiple architectures and varied datasets, is heavily dependent on the choice of parallel programming model and which features of the programming model are used. In this paper, we evaluate performance portability in the context of a data science workload in contrast to a scientific computing workload, evaluating the same sparse matrix kernel on both. Among our implementations of the kernel in different performance-portable programming models, we find that many struggle to consistently achieve performance improvements using the GPU compared to simple one-line OpenMP parallelization on high-end multicore CPUs. We show one that does, and its performance approaches and sometimes even matches that of vendor-provided GPU math libraries.

MANET stands for Mobile ad-hoc network, which is also known as a wireless network. It provides a routable networking environment which does not have a centralized infrastructure. MANET is used in many important sectors like economic sector (corporate field), security sector (military field), education sector (video conferences and lectures), law sector (law enforcement) and many more. Even though it plays a vital role in different sectors and improves its economic growth, security is a major concern in MANET. Due to lack of inbuilt security, several attacks like data traffic attack, control traffic attack. The wormhole is a kind of control traffic attack which forms wormhole link between nodes. In this paper, we have proposed an approach to detect and get rid of the wormhole attack. The proposed approach is based on trust values, which will decide whether nodes are affected by using parameters like receiving time and data rate. On evaluation, we have concluded that the wormhole attack decreases the network's performance while using trusted approach its value increases. Means PDR and throughput return best results for the affected network while in case of end to end delay it returns similar results as of unaffected network.

In emergency situations like recent Australian bushfires, it is crucial for civilians and firefighters to receive critical information such as escape routes and safe sheltering points with guarantees on information quality attributes. Mobile Ad-hoc Networks (MANETs) can provide communications in bushfire when fixed infrastructure is destroyed and not available. Current MANET solutions, however, are mostly tested under static bushfire scenario. In this work, we investigate the impact of a realistic dynamic bushfire in a dry eucalypt forest with a shrubby understory, on the performance of data delivery solutions in a MANET. Simulation results show a significant degradation in the performance of state-of-the-art MANET quality of information solution. Other than frequent source handovers and reduced user usability, packet arrival latency increases by more than double in the 1st quartile with a median drop of 74.5 % in the overall packet delivery ratio. It is therefore crucial for MANET solutions to be thoroughly evaluated under realistic dynamic bushfire scenarios.

Today we live in a hyper-connected world, where a large amount of applications and services are supported by ad hoc networks. They have a decentralized management, are flexible and versatile but their characteristics are in turn their main weaknesses. This work introduces a preliminary analysis of the evolution, trends and the state of the art in the context of the security in ad hoc networks. To this end, two different methodologies are applied: a bibliometric analysis and a Systematic Literature Review. Results show that security in MANETs and VANETs are still an appealing research field. In addition, we realized that there is no clear separation of solutions by line of defense. This is because they are sometimes misclassified by the authors or simply there is no line of defense that totally fit well with the proposed solution. Because of that, new taxonomies including novel definitions of lines of defense are needed. In this work, we propose the use of tolerant or survivable solutions which are the ones that preserve critical system or network services in presence of fault, malfunctions or attacks.

Mobile Ad-hoc Networks (MANET) is an autonomous network consisting of movable devices that can form a network using wireless media. MANET routing protocols can be used for selecting an efficient and shortest path for data transmission between nodes in a smart environment formed by the Internet of Things (IoT). Networking in such MANET-enabled IoT system is based on the routing protocols of MANET, data sensing from things, and data handling and processing using IoT. This paper studies proactive approach-based secure routing protocols for MANET-enabled IoT and analyses these protocols to identify security issues in it. Since this fusion network is resource-constrained in nature, each of the studied protocol is evaluated to check if it is lightweight or not. Also, the solution to defend against active attacks in this network is discussed.

In Mobile Ad-hoc Network based Internet of things (MANET-IoT), nodes are mobile, infrastructure less, managed and organized by themselves that have important role in many areas such as Mobile Computing, Military Sector, Sensor Networks Commercial Sector, medical etc. One major problem in MANET based IoT is security because nodes are mobile, having not any central administrator and are also not reliable. So, MANET-IoT is more defenseless to denial-of-service attacks for-example Blackhole, Wormhole, Gray-hole etc. To compare the performance of network under different attacks for checking which attack is more affecting the performance of network, we implemented Blackhole and Wormhole attack by modifying AODV routing protocol in NS-3. After preprocessing of data that is obtained by using Flow-monitor module, we calculated performance parameters such as Average Throughput, Average Packet Delivery Ratio, Average End to End Delay, Average Jitter-Sum and compared it with no. of nodes in MANET-IoT network. Throughput and goodput performance of each node in the network is also calculated by using Trace metric module and compared with each node in the network. This approach is also very helpful for further research in MANET-IoT Security.

Vehicle Ad-hoc Networks (VANETs) have recently become an active research area. This is because of its important applications in the transportation field in which vehicles have severe position during activities of daily living in persons. In this paper, the basic background of the VANET from the Intelligent Transportation System (ITS), Mobile Ad-hoc Networks (MANETs), VANET standard and VANET characteristics are discussed. Second, the architecture from components and communications of the system are presented. Then, the critical challenges and future perspectives in this field are comprehensively reviewed. This paper could serve as a guide and reference in the design and development of any new techniques for VANETs. Moreover, this paper may help researchers and developers in the selection of the main features of VANET for their goals in one single document.

A main type of Mobile Ad hoc Networks (MANET) and essential infrastructure to provide a wide range of safety applications to passengers in vehicles (VANET) are established. VANETs are more popular today as they connect to a variety of invisible services. VANET protection is crucial as its potential use must not endanger the safety and privacy of its users. The safety of these VANETs is essential to safe and efficient safety systems and facilities and uncertainty continues and research in this field continues to grow rapidly. We will explain the characteristics and problems of VANETs in this paper. Also, all threats and attacks that affect integrity and authentication in VANETs will be defined. Description of researchers' work was consequently addressed as the table with the problems of the suggested method and objective.

Security is the key concern, which allows safe communication between any two mobile nodes in an unfavorable environment. Wireless Ad Hoc can be unsecured against attacks by means of malicious nodes. Hence this study assesses the influence of wormhole attacks on Mobile Ad Hoc network (MANET) system that is evaluated and validated based on the QualNet simulator. The MANET performance is investigated utilizing the wormhole attacks. The simulation is performed on Mobile node's network layer and data link layer in the WANET (wireless Ad Hoc network). The MANET performance was examined using “what-if” analyses too. Results showed that for security purposes, it is indeed necessary to assess the Mobile Ad Hoc node deployment.

Vehicular Ad hoc Networks commonly abbreviated as VANETs, are an important component of MANET. VANET refers to the group of vehicles that are interlinked to one another through wireless network. Along with technology, comes the threats. Like other wireless networks, VANETs also are vulnerable to various security threats. Security in VANETs is a major issue that attracted many researchers and academicians. One small security breach can cause a big damage in case of VANETs as in this case human lives are involved. Intrusion Detection Systems (IDS) are employed in VANETs in order to detect and identify any malicious activity in the network. The IDS works by analysing the network and detecting any intrusions tried or made in the network so that proper steps could be taken timely to prevent damage from such activities. This paper reviews Intrusion Detection systems, classification of IDS based on various factors and then the architecture of IDS. We then reviewed some of the recent and important intrusion detection research works and then compared them with one another.

This advanced research survey aims to perform intrusion detection and routing in ad hoc networks in wireless MANET networks using machine learning techniques. The MANETs are composed of several ad-hoc nodes that are randomly or deterministically distributed for communication and acquisition and to forward the data to the gateway for enhanced communication securely. MANETs are used in many applications such as in health care for communication; in utilities such as industries to monitor equipment and detect any malfunction during regular production activity. In general, MANETs take measurements of the desired application and send this information to a gateway, whereby the user can interpret the information to achieve the desired purpose. The main importance of MANETs in intrusion detection is that they can be trained to detect intrusion and real-time attacks in the CIC-IDS 2019 dataset. MANETs routing protocols are designed to establish routes between the source and destination nodes. What these routing protocols do is that they decompose the network into more manageable pieces and provide ways of sharing information among its neighbors first and then throughout the whole network. The landscape of exciting libraries and techniques is constantly evolving, and so are the possibilities and options for experiments. Implementing the framework in python helps in reducing syntactic complexity, increases performance compared to implementations in scripting languages, and provides memory safety.

The Intrusion Detection System (IDS) is one of the technologies available to protect mobile ad hoc networks. The system monitors the network and detects intrusion from malicious nodes, aiming at passive (eavesdropping) or positive attack to disrupt the network. This paper proposes a new Intrusion detection system using three Machine Learning (ML) techniques. The ML techniques were Random Forest (RF), support vector machines (SVM), and Naïve Bayes(NB) were used to classify nodes in MANET. The data set was generated by the simulator network simulator-2 (NS-2). The routing protocol was used is Dynamic Source Routing (DSR). The type of IDS used is a Network Intrusion Detection System (NIDS). The dataset was pre-processed, then split into two subsets, 67% for training and 33% for testing employing Python Version 3.8.8. Obtaining good results for RF, SVM and NB when applied randomly selected features in the trial and error method from the dataset to improve the performance of the IDS and reduce time spent for training and testing. The system showed promising results, especially with RF, where the accuracy rate reached 100%.

A wireless technology Mobile Ad hoc Network (MANET) that connects a group of mobile devices such as phones, laptops, and tablets suffers from critical security problems, so the traditional defense mechanism Intrusion Detection System (IDS) techniques are not sufficient to safeguard and protect MANET from malicious actions performed by intruders. Due to the MANET dynamic decentralized structure, distributed architecture, and rapid growing of MANET over years, vulnerable MANET does not need to change its infrastructure rather than using intelligent and advance methods to secure them and prevent intrusions. This paper focuses essentially on machine learning methodologies and algorithms to solve the shortage of the first line defense IDS to overcome the security issues MANET experience. Threads such as black hole, routing loops, network partition, selfishness, sleep deprivation, and denial of service (DoS), may be easily classified and recognized using machine learning methodologies and algorithms. Also, machine learning methodologies and algorithms help find ways to reduce and solve mischievous and harmful attacks against intimidation and prying. The paper describes few machine learning algorithms in detail such as Neural Networks, Support vector machine (SVM) algorithm and K-nearest neighbors, and how these methodologies help MANET to resolve their security problems.

Mobile Ad hoc Networks ‘MANETs’ are still defenseless against peripheral threats due to the fact that this network has vulnerable access and also the absence of significant fact of administration. The black hole attack is a kind of some routing attack, in this type of attack the attacker node answers to the Route Requests (RREQs) thru faking and playing itself as an adjacent node of the destination node in order to get through the data packets transported from the source node. To counter this situation, we propose to deploy some nodes (exhibiting some distinctive functionality) in the network called DPS (Detection and Prevention System) nodes that uninterruptedly monitor the RREQs advertised by all other nodes in the networks. DPS nodes target to satisfy the set objectives in which it has to sense the mischievous nodes by detecting the activities of their immediate neighbor. In the case, when a node demonstrates some peculiar manners, which estimates according to the experimental data, DPS node states that particular distrustful node as black hole node by propagation of a threat message to all the remaining nodes in the network. A protocol with a clustering approach in AODV routing protocol is used to sense and avert the black hole attack in the mentioned network. Consequently, empirical evaluation shows that the black hole node is secluded and prohibited from the whole system and is not allowed any data transfer from any node thereafter.

In the recent years, mobile ad hoc wireless networks (MANETs) have experienced a tremendous rise in popularity and usage due to their flexibility and ability to provide connectivity from anywhere at any time. In general, MANETs provide mobile communication to participating nodes in situation where nodes do not need access to an existing network infrastructure. MANETs have a network topology that changes over time due to lack of infrastructure and mobility of nodes. Detection of a malicious node in MANETs is hard to achieve due to the dynamic nature of the relationships between moving node and the nature of the wireless channel. Most traditional Intrusion Detection System (IDS) are designed to operate in a centralized manner; and do not operate properly in MANET because data in MANETs is distributed in different network devices. In this paper, we present an Hierarchical Cooperative Intrusion Detection Method (HCIDM) to secure packets routing in MANETs. HCIDM is a distributed intrusion detection mechanism that uses collaboration between nodes to detect active attacks against the routing table of a mobile ad hoc network. HCIDM reduces the effectiveness of the attack by informing other nodes about the existence of a malicious node to keep the performance of the network within an acceptable level. The novelty of the mechanism lies in the way the responsibility to protect the networks is distributed among nodes, the trust level is computed and the information about the presence of a malicious is communicated to potential victim. HCIDM is coded using the Network Simulator (NS-2) in an ad hoc on demand distance vector enable MANET during a black hole attack. It is found that the HCIDM works efficiently in comparison with an existing Collaborative Clustering Intrusion Detection Mechanism (CCIDM), in terms of delivery ratio, delay and throughput.

Mobile Ad Hoc Network (MANET) is one of the types of Ad-hoc Network which is comprised of wireless in a network. The main problem in this research is the vulnerability of the protocol routing Dymo against jellyfish attack, so it needs detection from a jellyfish attack. This research implements the DELPHI method to detect jellyfish attacks on a DYMO protocol which has better performance because the Delay Per-Hop Indicator (DELPHI) gathers the amount of hop and information delay from the disjoint path and calculates the delays per-hop as an indicator of a jellyfish attack. The evaluation results indicate an increase in the end-to-end delay average, start from 112.59s in 10 nodes increased to 143.732s in 30 nodes but reduced to 84,2142s in 50 nodes. But when the DYMO routing did not experience any jellyfish attacks both the delivery ratio and throughput are decreased. The delivery ratio, where decreased from 10.09% to 8.19% in 10 nodes, decreased from 20.35% to 16.85%, and decreased from 93.5644% to 82.825% in 50 nodes. As for the throughput, for 10 nodes decreased from 76.7677kbps to 68.689kbps, for 30 nodes decreased from 100kbps to 83.5821kbps and for 50 nodes decreased from 18.94kbps to 15.94kbps.

One of the most dynamic network is the Mobile Adhoc (MANET) network. It is a list of numerous mobile nodes. Dynamic topology and lack of centralization are the basic characteristics of MANET. MANETs are prone to many attacks due to these characteristics. One of the attacks carried out on the network layer is the blackhole attack. In a black-hole attack, by sending false routing information, malicious nodes interrupt data transmission. There are two kinds of attacks involving a black-hole, single and co-operative. There is one malicious node in a single black-hole attack that can act as the node with the highest sequence number. The node source would follow the direction of the malicious node by taking the right direction. There is more than one malicious node in the collaborative black-hole attack. One node receives a packet and sends it to another malicious node in this attack. It is very difficult to detect and avoid black-hole attacks. Many researchers have invented black-hole attack detection and prevention systems. In this paper, We find a problem in the existing solution, in which validity bit is used. This paper also provides a comparative study of many scholars. The source node is used to detect and prevent black hole attacks by using a binary partition clustering based algorithm. We compared the performance of the proposed solution with existing solution and shown that our solution outperforms the existing one.

This study focuses on the behavior of magnetic properties and electromagnetic absorption of MgFe2O4 prepared by powder metallurgy. Magnesium ferrite was synthesized using oxide precursors (MgO and Fe2 O3). The samples were calcined at 700 °C for 3 hours and sintered at 1100 °C for 24 hours with varying compaction pressure (80 kg/cm2, 90 kg/cm2, 100 kg/cm2). Magnesium ferrites were characterized using an X-Ray Diffraction (XRD) for their crystal structure analysis, a Scanning Electron Microscope equipped with an Energy Dispersive Spectroscopy (SEM-EDS) for their microstructure and elemental composition studies, a Permagraph for their magnetic properties, and a Vector Network Analysis (VNA) for their microwave absorption characteristics. XRD patterns shows primary phase of MgFe2O4 and secondary phase of Fe2 O3 present in all three samples. The SEM characterization reveal the microstructure of magnesium ferrite and the EDS spectra confirm the presence of Fe, Mg, and O. The hysteresis curves show that the values of remanence magnetic induction (Br) are 17.5 emu/g, 16.5 emu/g, and 14.5 emu/g, respective to the increasing compaction pressure. Saturation magnetization values are increasing whereas the coercivity values are found to have inconsistent change with increasing compaction pressure. According to VNA results, the values of reflection loss are -16.15 dB, -22.45 dB, and -27.55 dB, respectively.

The circulating current in the D-winding may cause primary current waveform distortion, and the reliability of the restraint criterion based on the typical magnetizing inrush current characteristics will be affected. The magnetizing inrush current with typical characteristics is the sum of primary current and circulating current. Using the circulating current to compensate the primary current can improve the reliability of the differential protection. When the phase is not saturated, the magnetizing inrush current is about zero. Therefore, the primary current of unsaturated phase can be replaced by the opposite of the circulating current. Based on this, an engineering practical calculation method for circulating current is proposed. In the method, the segmented primary currents are used to replace the circulating current. Phasor analysis is used to demonstrate the application effect of this method when remanence coefficients are different. The method is simple and practical, and has strong applicability and high reliability. Simulation and recorded waveforms have verified the effectiveness of the method.

Aiming at the fact that the existing feature quantities cannot well identify the magnetizing inrush current during remanence and bias and the huge number of feature quantities, a new identification method using empirical mode decomposition energy index and artificial intelligence algorithm is proposed in 'this paper. Decomposition and denoising are realized through empirical mode decomposition, and then the corresponding energy index is obtained for the waveform of each inherent modal component and simplified by the mean impact value method. Finally, the accuracy of prediction using artificial intelligence algorithm is close to 100%. This reflects the practicality of the method proposed in 'this article.

In recent years, there have been situations in which the zero-sequence protection of the transformer has been incorrectly operated due to the converter transformer energizing or fault recovery. For converter transformers, maloperation may also occur. However, there is almost no theoretical research on the zero-mode inrush currents of converter transformers. This paper studies the characteristics of the zero-mode inrush currents of the converter transformers, including the relationship between the amplitude and attenuation characteristics of the zero-mode inrush currents of converter transformers, and their relationship with the system resistance, remanence, and closing angle. First, based on the T-type equivalent circuit of the transformer, the equivalent circuit of the zero-mode inrush current of each transformer is obtained. On this basis, the amplitude relationship of the zero-mode inrush currents of different converter transformers is obtained: the zero-mode inrush current of the energizing pole YY transformer becomes larger than the YD transformer, the energized pole YD becomes greater than the YY transformer, and the YY transformer zero-mode inrush current rises from 0. It is also analyzed that the sympathetic interaction will make the attenuation of the converter transformer zero-mode inrush current slower. The system resistance mainly affects the initial attenuation speed, and the later attenuation speed is mainly determined by the converter transformer leakage reactance. Finally, PSCAD modeling and simulation are carried out to verify the accuracy of the theoretical analysis.

Magnetic shielding is an important part in atomic clock’s physical system. The demagnetization of the assembled magnetic shielding system plays an important role in improving atomic clock’s performance. In terms of the drawbacks in traditional attenuated alternating-current demagnetizing method, this paper proposes a novel method — automatically attenuated alternating-current demagnetizing method. Which is implemented by controlling the demagnetization current waveform thorough the signal source’s modulation, so that these parameters such as demagnetizing current frequency, amplitude, transformation mode and demagnetizing period are precisely adjustable. At the same time, this demagnetization proceeds automatically, operates easily, and works steadily. We have the pulsed optically pumped (POP) rubidium atomic clock’s magnetic shielding system for the demagnetization experiment, the magnetic field value reached 1nT/7cm. Experiments show that novel method can effectively realize the demagnetization of the magnetic shielding system, and well meets the atomic clock’s working requirements.

This work investigates the impact of mechanical strain on wake-up behavior of planar HfO2 ferroelectric capacitor-based memory. External in-plane strain was applied using a four-point bending tool and strain impact on remanent polarization and coercive voltage of the ferroelectric was monitored. It was established that compressive strain is beneficial for 2Pr improvement, while tensile strain leads to its degradation, with a sensitivity of -8.4 ± 0.5 % per 0.1 % of strain. Strain-induced polarization rotation is considered to be the most likely mechanism affecting 2Pr At the same time, no strain impact on Vcwas observed in the investigated strain range. The results seen here can be utilized to undertake stress engineering of ferroelectric memory in order to improve its performance.

This work examines volatile memory modules as ephemeral key storage for security applications in the context of low temperatures. In particular, we note that such memories exhibit a rising level of data remanence as the temperature decreases, especially for temperatures below 280 Kelvin. Therefore, these memories cannot be used to protect the superconducting modules found in high-speed Magnetic Levitation (MagLev) trains, as such modules most often require extremely low temperatures in order to provide superconducting applications. Thus, a novel secure storage solution is required in this case, especially within the oncoming framework concept of the internet of railway things, which is partially based on the increasing utilisation of commercial off-the-shelf components and potential economies of scale, in order to achieve cost efficiency and, thus, widespread adoption. Nevertheless, we do note that volatile memory modules can be utilised as intrinsic temperature sensors, especially at low temperatures, as the data remanence they exhibit at low temperatures is highly dependent on the ambient temperature, and can, therefore, be used to distinguish between different temperature levels.

The behavior of the Current Transformer (CTs) is of utmost importance for protection engineers to ensure reliable operation of power system. CT magnetic saturation is a well-known phenomenon when analyzing its performance characteristics. Nevertheless, transient conditions in the system might be different every time. A good understanding of the magnetic saturation of different CT designs and the effect of saturation on the protection schemes is imperative for developing a robust and dependable protection system. In this paper, various factors that affect CT saturation like X/R ratio, large current magnitudes, DC offset, burden and magnetization remanence are discussed. Analysis of CT saturation based on changes to burden and remanence is performed. In addition to that, the effect of saturation due to these factors on distance protection are presented with test results and analysis. Saturation conditions are analyzed on mho distance elements during phase to ground and three phase faults. Finally, a practical approach to efficiently test the performance of protection schemes under CT saturation conditions is proposed using COMTRADE play back. COMTRADE play back files for various scenarios of CT saturation conditions are generated and used for testing the performance of the protection scheme.