Failure Path Research Articles

Low-Delay and Energy-Efficient Opportunistic Routing for Maritime Search and Rescue Wireless Sensor Networks

After the occurrence of a maritime disaster, to save human life and search for important property equipment in the first time, it is indispensable to efficiently transmit search and rescue sea area data to the maritime search and rescue command center (MSRCC) in real-time, so that the MSRCC can make timely and accurate decisions. The key to determining the efficiency of data forwarding is the quality of the routing protocol. Due to the high dynamics of the marine environment and the limited energy of the marine node, the coverage hole and routing path failure problems occur frequently when using the existing routing algorithm for marine data forwarding. Based on the above background, in this work, we study a low-latency and energy-efficient opportunistic routing protocol for maritime search and rescue wireless sensor networks (MSR-WSNs). Considering the adverse impact of wave shadowing on signal transmission, an effective link reliability prediction method is first investigated to quantify the link connectivity among nodes. To mitigate the end-to-end time delay, an optimal expected packet advancement is then derived by combining link con-nectivity with geographic progress threshold θ. After that, based on the link connectivity between marine nodes, the optimal expected packet advancement prediction, the distance from the sensing nodes to the sink, and the remaining energy distribution of the nodes, the priority of candidate nodes is calculated and sorted in descending order. Finally, timer-based coordination algorithm is adopted to perform the marine data packet forwarding so as to avoid packet conflict. Computer simulation results demonstrate that compared with benchmark algorithms, the data packet delivery ratio, the delay performance and the average node energy consumption (the average node speed is 20 m/s) of the proposed opportunistic routing protocol are improved by more than 21.4%, 39.2% and 18.1%, respectively.

Fuzzy Logic System Assisted Sensing Resource Allocation for Optical Fiber Sensing and Communication Integrated Network.

With the development of information transmission, there is an increasing demand for state monitoring of fiber-optic communication networks to improve the security and self-healing ability of the network. Distributed optical fiber sensing is one of the most attractive methods because it can achieve real-time detection of the whole network without additional sensing heads. However, when the sensing network is introduced into the communication network, the failure probability should be efficiently suppressed with limited sensing resources. In this paper, the fuzzy logic system is used to evaluate the impact of different sensing resource allocation on optical cable network quality. The link failure probability and path failure probability under the condition of uniform and non-uniform sensing resource allocation are simulated and analyzed, respectively. As shown in the analysis results, the failure probability under non-uniform allocation is significantly lower than under uniform allocation. In this paper, we discussed and addressed the allocation of the optical fiber sensing and communication integrated (OFSCI) network with the limited sensing resource for the first time. The results are helpful to develop an allocation strategy for optical fiber sensing and a communication integrated network with a higher robustness.

Identification of failure modes and paths of reservoir dams under explosion loads

Reservoir dams are large public facilities at risk of being damaged by explosion loads. Explosion accidents may not only affect people's life safety but also lead to property loss and ecological environment damage. This paper presents a method for identifying failure modes and paths of reservoir dams under explosion loads. First, the anti-explosion and failure characteristics of earth-rock dams, concrete gravity dams and concrete arch dams are analyzed through numerical simulations. Second, the failure modes and paths of different dams under explosion loads are given according to simulation results and actual structures of the dam and outbuildings. Finally, an identification method of main failure modes and paths of reservoir dams under explosion loads using the fuzzy analytic hierarchy process (FAHP) is further proposed by constructing the failure hierarchy structures. The case study results show that the proposed method can identify the major failure modes and paths of reservoir dams under explosion loads. This method can provide scientific basis and technical support for the risk analysis and safety protection of reservoir dams under explosion loads.

The Terahertz Channel Modeling in Internet of Multimedia Design In-Body Antenna

In this paper, the authors have emphasized on the perspectives of the Terahertz channel modeling in Internet of multimedia nano things (IoMNT) networks. A modulation technique targeting body-centric network is discussed. An analogy of a real Terahertz antenna is developed within a terahertz multi-layer modelling channel for a human skin tissue. As a result, the investigation of how signals at THz frequency band interact and transmit within the skin biomaterial. The human skin model used to collect data was selected to have four layers: epidermis, dermis, blood, and hypodermis, with the depth of the layers varying between normal human body values. It is revealed from the literature that the frequency and content have a substantial impact on path failure. The estimated path loss could thus differ considerably, but for a human skin model with depths of 0.21 mm, 1.23 mm, 1.38 mm, and 3.76 mm, the frequencies of 0.5-1.5 THz at the end distance resulted in a path loss estimated about 250-350 dB.

Resistance Spot-Welding of Dissimilar Metals, Medium Manganese TRIP Steel and DP590

Resistance spot-welding of dissimilar metals, medium manganese TRIP steel 7Mn and DP590, is carried out. The effects of single-pulse welding parameters and a double-pulse-tempering current on the quality characteristic parameters and mechanical properties of 7Mn/DP590 spot-welded joints are studied. The welding process parameters are optimized using the control variable method. The results show that the optimal process parameters under a single pulse are as follows: electrode pressure: 4.5 kN, welding current: 9 kA and welding time: 300 ms. The failure mode of the welding joint is partial pull-out failure (PF-TT). The welding parameters have great influence on the nugget diameter and thickness reduction. Expulsion, crack and shrinkage are displayed in the joint under high electrode pressure. Softening occurs in the heat-affected zone due to a strong halo effect in the single-pulse weld. The tempering zone on the DP590 side is 202.49 HV, which is the lowest hardness point, while the hardness of the nugget zone is 450 HV. The addition of the tempering current homogenizes the microstructure with different failure paths and eliminates the stress. The tensile shear force of the joint increases by 17.13%. The 7Mn Steel/DP590 resistance spot-welding joint is from the fusion line to the center of the nugget, and the microstructure is composed of plane crystal, cellular crystal, dendritic crystal and columnar crystal, in turn. The nugget zone is composed of lath martensite and a small amount of residual austenite. Fine quasi-spherical and lamellar interbedded cementites are formed in the tempering zone of the DP590-side heat-affected zone.

Research on a Random Route-Planning Method Based on the Fusion of the A* Algorithm and Dynamic Window Method

Path planning is a hot topic at present. Considering the global and local path planning of mobile robot is one of the challenging research topics. The objective of this paper is to create a rasterized environment that optimizes the planning of multiple paths and solves barrier avoidance issues. Combining the A* algorithm with the dynamic window method, a robo-assisted random barrier avoidance method is used to resolve the issues caused by collisions and path failures. Improving the A* algorithm requires analyzing and optimizing its evaluation function to increase search efficiency. The redundant point removal strategy is then presented. The dynamic window method is utilized for local planning between each pair of adjacent nodes. This method guarantees that random obstacles are avoided in real-time based on the globally optimal path. The experiment demonstrates that the enhanced A* algorithm reduces the average path length and computation time when compared to the traditional A* algorithm. After fusing the dynamic window method, the local path is corrected using the global path, and the resolution for random barrier avoidance is visualized.

Fatigue behaviour of re-entrant auxetic structures made of the aluminium alloy AA7075-T651

An investigation of the fatigue behaviour of the re-entrant auxetic structures made of the aluminium alloy AA 7075-T651 is presented in this study. The analysed auxetic structures represent a new class of cellular structures that show anomalous deformation responses such as negative Poisson’s ratio. In the proposed work, the influence of the unit cell orientation on the crack path and fatigue life was studied using experimental and computational approaches. The Low Cycle Fatigue (LCF) tests were performed at load control with the load ratio 0.1 in tension. In the LCF tests five loading levels were selected, and at least two tests were performed at each loading level. The same loading conditions were then applied in the computational model in the framework of the ANSYS software package, where a nonlinear kinematic material model was applied to obtain the stress–strain relationship. The strain-life approach, with consideration of the Morrow mean stress correction, was then used to obtain the fatigue life of the analysed auxetic structures. The experimental and computational results showed that the unit cell’s orientation has a minor influence on the fatigue life of both analysed auxetic structures, but impact on the direction of the fatigue failure path significantly.

Intertwine Connection-Based Routing Path Selection for Data Transmission in Mobile Cellular Networks and Wireless Sensor Networks

In a network setting, a sensor node's round-trip delay time over hostile nodes compromises the node's ability to transmit data from the sender node to the destination node. Minimum distance path discovery causes the path failure, since aggressive nodes are available. Node connectivity is poor which should cause the packet loss; it does not control more energy consumption, since packet broadcasting is repeated for many times using that path. So, the proposed intertwine connection-based routing path selection (ICBRPS) technique allows only energy efficient routing path, path connectivity is important, and routing path is damaged because of the presence of aggressive nodes. It hacks the information from sensor and operates unpredictable manner. The objective of this presented ICBRPS scheme is to improve the routing path in efficient manner. If any damages occur during the transmission of data, then the alternate best node connectivity path is created by energetic route discovery method. The performance metrics of parameters are delay, network overhead, energy consumption, packet loss, packet delivery ratio, and connectivity ratio. It enhances the connectivity rate and reduces the energy consumption.

Failure Mode and Optimization for MSCSS with LRBs Based on IDA Method

The mega-sub controlled structure system with laminate rubber bearings is an emerging seismic control system for high-rise buildings. The system is high-order statically indeterminate with numerous failure modes. To study the failure modes of the structural system and further improve its seismic performance, the dynamic equations and the finite element model of the system were established. Ten different ground motions were selected from the Pacific Earthquake Engineering Research Center ground motion database for the incremental dynamic analysis (IDA). Based on the results of the IDA, the weakest failure mode of the system was identified, and its failure path was found. Two schemes were proposed to optimize the weakest failure mode of the system, and the optimization results were compared. The results show that although the IDA curves from different ground motion inputs are diverse, the plastic hinges are all formed on the sub-structures. Failures of the system are caused by either the excessive floor drift or the excessive shear deformation of rubber bearings. By adjusting the locations and parameters of dampers and rubber bearings, the seismic performance of the system can be improved.

Low velocity impact behavior of sandwich composites with different structural configurations of foam core: An experimental study

In this study, various structural configurations such plain core, two-core, epoxy columns in the core, core stitched, and facesheet stitched were designed in the foam core sandwich composite with the aim to increase the absorbed energy and to decrease core/facesheet debonding area due to low-velocity impact. Glass fiber/epoxy and PVC foam were used as a facesheet material and a core material, respectively. The impact energy values were selected considering to penetration and perforation cases. The core stitching effect on low velocity impact behavior of sandwich composites were compared to facesheet stitching and it has been determined that the core stitching process can be an alternative to the facesheet stitching process in terms of the absorbed energy value. Impacted sandwich composites are investigated for core/facesheet debonding; the modifications through the thickness increased the failure path for core/facesheet debonding initiation and the results show that a significant decrease in the core/facesheet debonding area has been achieved.

Prediction of Failure Path Current for Synchronous Reluctance and Interior Permanent Magnet Synchronous Machines Accounting for Saturation

This article proposes a model for obtaining the failure path current and torque waveforms in synchronous machines with saliency under interturn short circuits (ISC). The variations of the magnetomotive force (MMF) due to an ISC can lead to changes in the inductances, which lead to errors when modeling motors with ISC. A compact approach based on complex numbers is proposed to solve the dynamic ISC equation. The proposed method uses rotor reference frame variables and parameters as inputs. These rotor reference frame quantities are transformed to a stationary frame aligned with the faulted coil, thus extracting the real part of these quantities, allowing to solve the ISC dynamic equation quickly. Look-up tables are implemented to account for the MMF variations due to an ISC and saturation. The proposed model is validated with finite element analysis and experiments.

Optimizing QoS-Based Clustering Using a Multi-Hop with Single Cluster Communication for Efficient Packet Routing

Modern day communication systems have gained a revolutionized growth in long-distance wireless data transmission. High speed packet transfer impacts quality requirements. Critical factors that ruin service quality (Qos) are calculated by the primary factors involving power efficiency, packet delivery ratio, and overall transmission and reception delay. A well-developed routing protocol with unique attributes should be deployed to give improved QoS. The drawback of single path routing in delivering a packet at traffic is challenging since it does not have an alternative path in case of path failure. This problem can be targeted by a properly structured protocol with a multipath mechanism. In this article, Multi-hop with single cluster (SCMC) protocol is designed to increase the overall system efficiency by improving bandwidth, packet delivery ratio (PDR), reducing communication delay, and quality improvement. Adopting a single cluster and several hop protocol achieves power conservation for an additional period and balances the energy level. In multi hopping communications, numerous paths with various members can be produced by a single cluster is an added advantage. The proposed work is tested in NS-2 in comparison with equal cost multipath and protocol SPEED. The outcome of the designed protocol outperforms all other protocols in terms of minimum latency, lower power usage and improved packet delivery ratio

A computational approach for real-time stochastic recovery of electric power networks during a disaster

Disasters are occurring with increasing frequency worldwide, causing significant social hardship and economic losses. Critical infrastructures such as electric power networks are prone to failure under such events, and this significantly impacts the daily lives of people in affected areas. It is hence critical that the restoration planning of these power networks be done proactively. Disaster response in power networks is a well-studied problem, especially for pre-and post-event restoration Similar to pre-event, we consider uncertainty associated with the failure paths, and we look into real-time response while failures are happening. In this regard, at each time step, we move repair teams towards distribution loads based on their current state, their likelihood to fail, and the impact of the damage in case of node failure. We consider large-scale networks (>50 nodes and >20 repair teams) and propose an efficient algorithm to support real-time recovery.In particular, to address the curse of dimensionality, we design a novel approximate dynamic program that (i) evaluates the future impact of current actions using rollout, (ii) reduces the action space relying on aggregate dynamic programming. The proposed approach is applied to the power distribution network in Aguada municipality, Puerto Rico. Our results show that the proposed rollout approach significantly improves the network service level compared to the base heuristic through prepositioning of the repair crew. Moreover, we find that the performance gap grows larger with the concave restoration function (i.e., a decreasing Rate of Increase in the Load Service Level as the recovery progresses) compared to the linear restoration (a constant recovery rate throughout the recovery operation). Finally, the performance gap also grows larger under stronger failure scenarios.

Crowd navigation in an unknown and complex environment based on deep reinforcement learning

AbstractWe propose a virtual crowd navigation approach based on deep reinforcement learning to improve the adaptability of virtual crowds in an unknown and complex environment. To address the problem of local optimum or slow iteration or even failure to converge due to sparse rewards in complex environments, we integrate the curiosity‐driven mechanism, the key navigation points acquisition and the failure path penalty method in addition to combining long short‐term memory networks, dynamic obstacle collision prediction with proximal policy optimization algorithms, which realizes the crowd navigation in a complex environment. The experimental results show that the proposed approach can simulate the motions of virtual crowds in various dynamic and complex scenarios without the environment modeling. The use of continuous action space also ensures that the movement trajectories of the virtual crowds are more realistic and natural. Furthermore, our approach can provide analysis and demonstration tools for a variety of independent collaborations such as competition and cooperation of group intelligence in an open and dynamic environment.

Predictive impact of the Global Limb Anatomic Staging System (GLASS) on perioperative outcomes in patients with chronic limb-threatening ischaemia with isolated below-the-knee lesions.

Although the global vascular guidelines recently proposed the Global Limb Anatomic Staging System (GLASS) as an anatomical classification for chronic limb-threatening ischaemia (CLTI), prediction of perioperative outcomes using the GLASS classification in patients with CLTI due to isolated below-the-knee (BTK) lesions has not been well studied.This retrospective study included 585 patients with CLTI due to isolated BTK lesions who underwent endovascular therapy (EVT). The severity of arterial lesions was graded using the GLASS infrapopliteal (IP) and inframalleolar (IM) classifications and defined as follows: non-severe IP, 0-3; severe IP, 4; non-severe IM, P0-1; and severe IM, P2. The outcome measures were technical failure, defined as recanalisation failure of the target artery path, and perioperative failure, defined as a composite of all-cause death, major amputation, or repeat revascularisation within 30days.Technical and perioperative failures occurred in 9.4% (n = 55) and 9.9% (n = 58) patients, respectively. Compared to patients with non-severe IP and IM, those with both severe IP and IM were significantly associated with technical and perioperative failures (odds ratio [OR]: 13.87 [95% confidence interval (CI) 4.69-41.02, P < 0.001] and OR: 2.18 [95% CI 1.08-4.38, P = 0.041], respectively).The GLASS classification may have predictive value for technical and perioperative failure in patients with CLTI due to isolated BTK lesions after EVT.

Combined Effect of Pore Water Overpressure, Far-Field Stresses, and Strength Parameters in Wellbore Stability

Studying the stability of wellbores drilled to access reservoirs can be a challenging issue in overpressured basins because accurate estimation of the far-field stresses, overpressure, and rock strength parameters can be difficult to achieve. Unexpected overpressures can induce tensile stresses around the wellbore, and the selection of an appropriate strength criterion and rock properties play an important role in determining the limit mud pressures. This study focuses on the stability analysis of wellbores by considering the mutual interaction of far-field stresses, fluid overpressure, and strength parameters of isotropic rock. We performed sensitivity analyses with the Mohr–Coulomb and Hoek–Brown criteria in two overpressured fields (North Sea basin and Browse basin) to highlight the influence of the uncertainties related to the rock strength. We defined an effective stress path (ESP) failure line to analyze the failure limit condition in the tension and compression zone. The analysis results indicated that the Hoek–Brown criterion better describes rock failure conditions, especially in the tension zone. Furthermore, we suggested using two different frictional components of strength for the tension and compression zone because it is a conservative approach, particularly at high overpressures. The mud pressures obtained from the uniaxial radial/tangential (HF) conventional analysis give different failure limits with respect to the ESP approach suggested in this study. These differences are low, and the mud weight margin can be low. In addition, we carried out numerical simulations with FLAC to investigate the extent of failure. The results indicated that the mud weight margin between the onset of local failure and borehole collapse is very low at high overpressures. Finally, the geomechanical analysis of wellbore stability in overpressured basins indicated the need for improving the accuracy in determining the strength parameters of the rock.

Fire risk assessment of battery transportation and storage by combining fault tree analysis and fuzzy logic

Battery transportation and storage is an important part in the whole lifespan of batteries. It's significant to make a way to assess the fire risk of batteries during transportation and storage preventing from fire accident. This study presents a novel fire risk assessment method for lithium-ion batteries during transportation and storage. 8 possible failure paths and 9 basic events are deduced by fault tree analysis method. Likehood, severity, and hazard control number are selected as indexes for assessing the hazard risk number (HRN) of each possible failure path and fire accident. To comprehensively assess the value of these indexes, corrosponding sub-indexes are proposed and analyzed by synthesis through fuzzy logic method. To ensure the safety of batteries, four parameters including the synthesis HRN, HRNs of all possible paths, likelihood and severity of all basic events are suggested to set the limitation. The case study of battery transportation by marine verified the proposed method can accurately assess fire risk and locate the possible problems.

A Study of Fatigue Crack Propagation Paths at U-Rib Welds in Orthotropic Bridge Decks using a Phased-Array Imaging Technique

In this paper, the fatigue failure mode of single- and double-sided welded joints in orthotropic bridge decks is innovatively investigated with the phased-array imaging technique for verifying the fatigue failure path defined using the traction structural stress method. The full-scale fatigue specimen tests are conducted, and the fatigue depth and length are imaged and sized for the completeness of fatigue crack propagation law. It can be concluded that the fatigue failure mode of single- and double-sided welded joints is proven to be the thickness-through mode, which is consistent with the fatigue failure path defined in the traction structural stress method. The analysis method for calculating the main characters is first proposed, and the fatigue crack propagation law of the crack length and depth in the through-thickness mode is determined for completeness.

Engineering the failure path with bird feather inspired novel cellular structures

In this study, novel cellular structures designs are derived from venation patterns found in bird feathers. The designed structures are 3D printed using fused filament fabrication (FFF) method. All the structures are printed with acrylonitrile butadiene styrene (ABS) material. Printed structures are subjected to quasi-static tensile loading condition. In-situ digital image correlation technique (DIC) is used to study the fracture and crack propagation behavior in the cellular structures. Furthermore, finite element method (FEM) is also used to study the crack propagation and strain field contour. Here an attempt has been made to explore the possibility of engineering the crack path by controlling the design of the cellular structures. The novel designs showed local shear bands and based on the design it is possible to change the direction of shear bands. Furthermore, the effect of unit cell size and barbs angles of inclination on the crack propagation and mechanical properties is also studied. The increased length of the shear band can increase the post yielding strain, fracture energy and fracture toughness, which reduces the chances of sudden global failure of the structures. Hence this study opens an avenue for the advanced functional materials with tunable and fail-proof designs.

Maintenance analysis of transportation networks by the traffic transfer principle considering node idle capacity

Traffic congestion is a universal challenge that affects urban transportation networks, which inevitably age and deteriorate. Maintenance is an essential method for alleviating road congestion. Most of the previous studies concentrate on node load and capacity analysis. The capacity of an idle node is also an important element that affects traffic congestion, such as road damage or traffic accident at the crossroads. To explore the effect of the capacity of an idle node on road congestion, this paper introduces a traffic transfer principle to improve road maintenance efficiency. The nodes of a traffic network can be ranked based on their failure severity. The failure paths of a traffic network can be identified through the internal connections between nodes. Using the transfer time as the weight of each edge and the service time as the weight of each node, this paper proposes a maintenance model to find the shortest repair path for minimizing the maintenance time. To evaluate the proposed model, four different types of road networks are adopted by comparing the maintenance time. The experimental results show the proposed model outperforms previous models.