Reliability Problems Research Articles

Incremental learning of parameter spaces in machine-learning based reliability analysis

Significant advances in machine-learning based reliability analysis occurred recently. These allowed it to be performed with high effectiveness. However, in most applications the problem of reliability is treated within a closed setup, and if a change in the problem is needed a posteriori, the reliability needs to be re-assessed, which often results in an inefficient usage of resources.In this context, the present work argues that established reliability knowledge can inform the assessment of a similar problem under parameter changes. It uses incremental learning in an augmented space to solve a reliability analysis with dependence on parameter variations. It is shown that only the points that swap their classification are of interest to reassess reliability, which has large synergy with machine learning and classification.A learning approach that uses this synergy is proposed to search for the points that are under a class change. It is tested in four examples and uses adaptive kriging. The results show that with only few additional evaluations of the true function it is possible to accurately (at <1% loss in accuracy) assess the reliability for a relatively complex problem experiencing changes in its parameters.This approach opens a new frontier on the topic and is aligned with the demand for dynamic assessment techniques in engineering decision-making processes.

Fracture behavior and constitutive relations of Sn-3.0Ag-0.5Cu solder alloy at cryogenic temperature

The mechanical behavior, underlying fracture mechanism and constitutive relations of Sn-3.0Ag-0.5Cu (SAC305) solder alloy at cryogenic temperature through in-situ uniaxial tensile experiments were investigated over a wide temperature range of 293 K–77 K. The activation of deformation twin in the solder alloy contributes to improve the tensile strength and quasi-static toughness, and maintains the fracture elongation at 35–45% with the decline of ambient temperature. SAC305 solder alloy with a mixed mode of ductile and brittle fracture achieves the optimal balance of strength, ductility and toughness at 123 K, and the large mismatch between twins thickening rate (∼13 μm/s) and dislocation slip velocity (∼3.6 μm/s) finally leads to the brittle fracture at 77 K. In addition, Anand model as a unified viscoplastic constitutive law has been employed to describe the constitutive relations of SAC305 solder alloy and fails in fitting the stress-strain curves at invalid temperature below 233 K. Hollomon equation is conducted to perfectly characterize the constitutive relations of the alloy at temperatures lower than 233 K. The method for controlling the formation of deformation twins in the solder alloy and solder joints is really beneficial to solve the reliability problems for cryogenic electronics.

귀국 직장인의 민족정체성과 심리사회적 적응의 관계

Objectives The aim of this study was to examine the moderated mediating effect of the acculturation strategy on the relationship with the impact of changed ethnic identity on reverse cultural shock and psychological social adaption to adults who returned to work after living abroad.&#x0D; Methods The survey was conducted between February 22 and March 27, 2020 on 202 adults who returned to Korea and are working after living abroad for at least 3 years, and collected data that did not consent to the collec-tion and use of personal information, excluding those, 199 copies were used as final analysis data. The mediation effect, the moderation effect and the moderated mediating effect were analyzed through SPSS 25.0 and SPSS Macro.&#x0D; Results The results were as follows; The reverse culture shock was significant on the relationship between the ethnic identity and psychological social adaption. Also the moderation effect of assimilation and separation strat-egies was verified on the relationship between reverse cultural shock and psychological social adaption even though there was a limitation in investigating the moderated mediating effect of the integration strategy, which is a sub-strategies of acculturation strategy due to the reliability problem. Lastly, assimilation and separation strategies moderated the mediating effect of reverse cultural shock between internalized ethnic identity and psy-chological social adaption.&#x0D; Conclusions These findings showed the impact of ethnic identity and reverse cultural shock on psychological so-cial adaptation, and high level of assimilation and low level of separation strategies were expected to be risks for psychological social adaptation. Finally, the implications and limitations of this study were discussed.

Study on Cable Tension Characteristics of Shore-Based Constant Tension Mooring Systems Under the Coupling Effect of Wind, Wave, and Current

Abstract This paper proposes a shore-based constant tension mooring system, which improves the cable tension distribution by adjusting the length of the cable to maintain the constant tension of the cable between the ship and the mooring pile in order to solve the problem of poor safety and reliability of the traditional mooring system in the mooring process. First, based on the three-dimensional potential flow theory, this paper uses the hydrodynamic software AQWA to numerically simulate the dynamic response of the traditional mooring system under the coupling of wind, wave, and current in different sea states. Subsequently, a shore-based constant tension mooring system using the principle of volume-varying hydraulic control was studied. On the basis of a comprehensive analysis of the working principle of the constant tension hydraulic control mooring system, a mathematical model of the main working circuit is established. The system was numerically simulated by relying on matlab/Simulink simulation software. Finally, by comparing with traditional mooring systems, the results show that the maximum cable tension of the shore-based constant tension mooring system is significantly reduced so that the tension is controlled within a fixed range, and the safety factor of the mooring cable is significantly improved, thus reducing the risk of mooring system failure and improving the ship's survivability.

RC-LAHR: Road-Side-Unit-Assisted Cloud-Based Location-Aware Hybrid Routing for Software-Defined Vehicular Ad Hoc Networks.

The reliability of the communication link is quite common and challenging to handle as the topology changes frequently in vehicular ad hoc networks (VANETs). Another problem with VANETs is that the vehicles are from different manufacturers. Hence, the heterogeneity of hardware is obvious. These heterogeneity and reliability problems affect the message dissemination in VANETs. This paper aims to address these challenges by proposing a robust routing protocol capable of ensuring reliable, scalable, and heterogeneity-tolerant message dissemination in VANETs. We first introduced a hybrid hierarchical architecture based on software-defined networking (SDN) principles for VANETs, leveraging SDN's inherent scalability and adaptability to heterogeneity. Further, a road-side unit (RSU)-assisted cloud-based location-aware hybrid routing for software-defined VANETs (SD-VANETs) that we call RC-LAHR was proposed. RC-LAHR was rigorously tested and analyzed for its performance in terms of packet delivery ratio (PDR) and end-to-end delay (EED), along with a comprehensive assessment of network traffic and load impacts on cloud infrastructure and RSUs. The routing protocol is compared with state-of-the-art protocols, Greedy Perimeter Stateless Routing (GPSR) and Opportunistic and Position-Based Routing (OPBR). The proposed routing protocol performs well as compared to GPSR and OPBR. The result shows that the EED is reduced to 20% and the PDR is increased to 30%. The network reliability is also increased up to 5% as compared to the OPBR and GPSR.

Displacement Self-Sensing Control of Permanent Magnet Assisted Bearingless Synchronous Reluctance Motor Based on Least Square Support Vector Machine Optimized by Improved NSGA-II

In order to solve the problems of low integration, low reliability, and high cost caused by mechanical sensors used in bearingless synchronous reluctance motor (PMa-BSynRM) control system, a novel displacement self-sensing control method using a least square support vector machine (LSSVM) left inverse system is proposed. Firstly, the working principle of the PMa-BSynRM is introduced and the mathematical model of the PMa-BSynRM is derived. Secondly, the observation principle of the left-inverse system of the PMa-BSynRM is explained and the left-invertibility of the displacement subsystem is proved. Thirdly, the improved NSGA-II algorithm is utilized to optimize the the regularization parameter and the bandwidth of LSSVM, and the displacement self-sensing control system is constructed. The simulations of speed variation and anti-interference are performed, which proves the dynamic tracking performance of the displacement. Finally, the static suspension, speed variation and anti-interference experiments are carried out. The feasibility and reliability of the proposed displacement self-sensing method are verified.

A novel reliability analysis methodology based on IPSO-MCopula model for gears with multiple failure modes

In order to accurately and quickly predict the failure probability of gears with multiple failure modes, a novel reliability analysis methodology based on the mixed Copula (MCopula) function model is proposed to deal with the complex correlation among different failure functions. Firstly, we construct a novel MCopula model based on three famous Copula functions: Gumbel Copula, Clayton Copula, and Frank Copula functions. Secondly, we use and improve the particle swarm optimization (PSO) method to optimally calculate the weight coefficients in the proposed MCopula model. Thirdly, the maximum likelihood estimation (MLE) method is adopted to estimate related parameters in the proposed MCopula model. Finally, we verify the proposed reliability analysis methodology with a standard life-prediction case of a strut system and a practical life-problem case of a gear pair system. Comparison results of both cases show that, by using the proposed methodology, the failure probability of a gear pair system with multiple failure correlations can be quickly calculated through a small number of samples and can be estimated as accurately as that by the Monte Carlo scheme. Consequently, our proposed novel methodology successfully analyzes the reliability problems for a gear pair system with multiple failure modes. The proposed methodology can be further applied to solve the reliability problem for other machine parts.

Research on ecosystem detection based on wireless communication network

Ecosystem monitoring is of great significance in environmental protection and sustainable development. Wireless communication networks provide a broad application prospect for ecosystem monitoring, but there is a lack of further research on the strengths and weaknesses of the existing research results and specific application scenarios, as well as on the reliability of data processing. This paper aims to explore the theoretical basis of the reliability of wireless communication networks in ecosystem monitoring. Firstly, the current status, characteristics and challenges of wireless communication networks in ecosystem monitoring are reviewed, the key elements in ecosystem monitoring and the requirements for data integrity and accuracy are analyzed in detail, and the reliability problems of signal interference, node failure and data loss in data transmission are discussed. Secondly, methods and strategies to improve the reliability of ecosystem monitoring based on wireless communication networks are explored. By reviewing and analyzing the existing research results, the advantages and disadvantages of different methods as well as the applicable scenarios are elaborated. Finally, the paper proposes directions and challenges for future research. The exploration of emerging technologies is emphasized. At the same time, issues that need to be addressed, network security, energy efficiency and cost feasibility are pointed out. The significance of this paper in academic and industry practice can further deepen the exploration of the theoretical basis of reliability and combine it with practical application scenarios for verification and optimization.

Current state and problems of reliability of power supply systems of electrical complexes of industrial enterprises

In accordance with the Energy Strategy of Russia until 2035 and the Decree of the Government of the Russian Federation "Improving the reliability and quality of power supply to consumers of electric energy through the introduction of new technologies and optimization of the activities of territorial grid organizations", the issues of improving the reliability of power supply of electrical complexes of industrial enterprises in a market economy are of particular importance.This article presents the results of a survey of managers and specialists of the services of the chief power engineer of industrial enterprises, representatives of design institutes, equipment manufacturers, university researchers on the existing problems of reliability of power supply systems of industrial enterprises. The expediency of substantiating the identification of the current situation by the main reliability indicators and their relationship in the existing economic conditions for calculating the reliability of power supply systems is substantiated. A comparative analysis of the responses of respondents of energy services is presented, their interpretation is given.The main problems in the following blocks are identified: the quality of the enterprise's energy supply and its reliability; the reliability of energy distribution within the enterprise and control of the influence of installed electrical equipment on the quality of the electrical network; knowledge regarding reliability and interest in carrying out such calculations. Recommendations are given on the identified problems, including the analysis of individual indicators of reliability of power supply to industrial enterprises.

Complementing Hi-C information for 3D chromatin reconstruction by ChromStruct.

A multiscale method proposed elsewhere for reconstructing plausible 3D configurations of the chromatin in cell nuclei is recalled, based on the integration of contact data from Hi-C experiments and additional information coming from ChIP-seq, RNA-seq and ChIA-PET experiments. Provided that the additional data come from independent experiments, this kind of approach is supposed to leverage them to complement possibly noisy, biased or missing Hi-C records. When the different data sources are mutually concurrent, the resulting solutions are corroborated; otherwise, their validity would be weakened. Here, a problem of reliability arises, entailing an appropriate choice of the relative weights to be assigned to the different informational contributions. A series of experiments is presented that help to quantify the advantages and the limitations offered by this strategy. Whereas the advantages in accuracy are not always significant, the case of missing Hi-C data demonstrates the effectiveness of additional information in reconstructing the highly packed segments of the structure.

A novel structure adaptive discrete grey Bernoulli prediction model and its applications in energy consumption and production

It is well known that energy forecasts play an important role in guiding energy policy, economic development and technological progress. Therefore, based on the purpose of energy consumption and production forecasting, this paper proposes a novel structure adaptive discrete grey Bernoulli model, which is innovative in terms of both accumulated generating operator and model structure. In terms of accumulated generating operator, a new fractional order accumulated generating operator is proposed in this paper. The new accumulated generating operator has a different information priority by adjusting the values of the parameters. In terms of model structure, a novel discrete grey Bernoulli model is proposed in this paper. The novel model is well adapted to time series data containing nonlinear information, and can well mine and utilize the information contained in the original data. In addition, the Particle Swarm Optimization (PSO) algorithm was chosen to optimize the model parameters based on algorithm comparison experiments. This enables the model to flexibly adapt to a variety of complex data and has the ability of structure adaptive. Moreover, this paper conducts comparative experiments between the novel model and eight other forecasting algorithms for time series data. The numerical results show that the novel model has better forecasting performance for the data of China’s total energy consumption, China’s total electricity generation and China’s total domestic electricity consumption. In addition, for the model reliability problem caused by the optimization algorithm, the stability and accuracy of the model are verified by Monte Carlo simulation and probability density visualization analysis. Finally, the proposed model predicts the future development trend of energy consumption and production in China.

Dynamic reliability calculation of random structures by conditional probability method

For the composite random reliability problem, based on the Markov hypothesis of the dynamic response spanning action, two procedures of conditional probability explanation are accomplished: to derive the 2nd-order approximate expression for the calculation of the dynamic reliability of the random structure based on Taylor expansion method; secondly is to determine a mathematical sampling technique based on the Kriging model derive from the statistical analysis. Between them, the sampling procedure by the Kriging interpolation model meets the nonlinear correlation among dynamic reliability and structural random boundaries. Consequently, the finite element results can be used instantly to anatomize the significance of random structural parameters on dynamic reliability, avoiding the tedious and cumbersome theoretical derivation. The numerical example outcomes demonstrate that the numerical sampling method established upon the Kriging model is inconsiderate to the ratio to represent the dispersion and has additional benefits in computational verisimilitude and calculation productivity

Power Quality as a Reliability Problem for Electronic Equipment.

Power quality standards introduce the definitions of several power quality disturbances and define limits for their amplitudes, repetition rates and, or maximum number of occurrences in a time period. The definitions of those parameters result from the observation of the disturbance phenomena in the networks and are not related with the consequences of power quality disturbances in the reliability of electronic equipments. In this paper, are described the main reliability effects caused by power quality problems, in electronic equipment. The authors explain the physical limitations of power supplies, concerning power quality problems and developed a simple, low cost power quality analyser, designed for the evaluation of the parameters that are critical to the failure rates of electronic equipment.

A Comparative Study on the Degradation Behaviors of Ferroelectric Gate GaN HEMT with PZT and PZT/Al2O3 Gate Stacks.

In this paper, the degradation behaviors of the ferroelectric gate Gallium nitride (GaN) high electron mobility transistor (HEMT) under positive gate bias stress are discussed. Devices with a gate dielectric that consists of pure Pb(Zr,Ti)O3 (PZT) and a composite PZT/Al2O3 bilayer are studied. Two different mechanisms, charge trapping and generation of traps, both contribute to the degradation. We have observed positive threshold voltage shift in both kinds of devices under positive gate bias stress. In the devices with a PZT gate oxide, we have found the degradation is owing to electron trapping in pre-existing oxide traps. However, the degradation is caused by electron trapping in pre-existing oxide traps and the generation of traps for the devices with a composite PZT/Al2O3 gate oxide. Owing to the large difference in dielectric constants between PZT and Al2O3, the strong electric field in the Al2O3 interlayer makes PZT/Al2O3 GaN HEMT easier to degrade. In addition, the ferroelectricity in PZT enhances the electric field in Al2O3 interlayer and leads to more severe degradation. According to this study, it is worth noting that the reliability problem of the ferroelectric gate GaN HEMT may be more severe than the conventional metal-insulator-semiconductor HEMT (MIS-HEMT).

On assessing the reliability of real-time systems at the operational stage

Information management systems operating in real time are characterized by increased reliability requirements. The problem of reliability is becoming increasingly important due to the constant complication of the systems being developed, the expansion of the range of tasks assigned to them, is complex and relevant in modern conditions. Reliability assessment methods and models are constantly being developed and refined, since reliability is one of the key quality problems of modern distributed real-time systems. The article discusses methods for ensuring the reliability of complex systems at the operational stage. Approaches for evaluating reliability indicators of complex systems at the operational stage are presented. The issues of ensuring the reliability of complex systems at the stage of operation are considered. The basic basic concepts of reliability are defined. Approaches for evaluating reliability indicators of complex systems at the operational stage are presented. The analysis of models and methods for assessing the reliability of complex systems at the operational stage is carried out.

Some problems of reliability of structural health monitoring

Analysis of stress state and strength of piezoelectrical transducer (PET) in-built to structural component which loaded by static or cyclic load is done. All results and conclusions are applicable for thin PET of rectangular shape. The data of the fatigue test of reinforced Al-alloy panel and FEA results were used. The general statistical estimation of fatigue test data was made. The high probability of PET destruction at the cyclic load of typical level is shown for considered conditions. The detailed FEA of in-built PET stress state is performed, and in this base the development of brittle PET destruction at monotonically increasing load was predicted as equi-fragmental crushing (EFC) and its properties were described. The EFC process was adapted to PET destruction at cyclic load and used for construction of likelihood estimation (LHE) of the fatigue strength of PET. Using LHE model, the estimation of parameters of the normal distribution of the fatigue strength was obtained. The general comparison of in-built PET strength and PET at pure tension is given.

Reliability of an automatic fire sprinkler installation in a woodworking shop

The article examines and evaluates in detail the problem of reliability of an automatic fire protection system. Several solutions are proposed to enhance the fire safety of technological processes and the continuous production of combustible materials (wood).

Impact of quality and transparency in scientific writing on the reduction of animal usage in experimental protocols: a review based in pertinent literature.

The irreproducibility in scientific research has become a critical issue. Despite the essential role of rigorous methodology in constructing a scientific article, more than half of publications, on average, are considered non-reproducible. The implications of this irreproducibility extend to reliability problems, hindering progress in technological production and resulting in substantial financial losses. In the context of laboratory animal research, this work emphasizes the importance of choosing an appropriate experimental model within the 3R's principle (Refine, Reduce, Replace). This study specifically addresses a deficiency in data specification in scientific articles, revealing inadequacies in the description of crucial details, such as environmental conditions, diet, and experimental procedures. For this purpose, 124 articles from journals with relevant impact factors were analyzed, conducting a survey of data considered important for the reproducibility of studies. Important flaws in the presentation of data were identified in most of the articles evaluated. The results of this study highlight the need to improve the description of essential information, standardizing studies, and ensuring the reproducibility of experiments in areas such as metabolism, immunity, hormones, stress, among others, to enhance the reliability and reproduction of experimental results, aligning with international guidelines such as ARRIVE and PREPARE.

АНАЛИЗ РАЗВИТИЯ СТАТИСТИЧЕСКИХ МЕТОДОВ ОЦЕНКИ НАДЕЖНОСТИ КАК СВОЙСТВА КАЧЕСТВА ОБЪЕКТОВ И ПРОДУКЦИИ

Reliability is the most important characteristics of any object or product, since it is always important that what the supplier offers and supplies is of high quality not only at the time of purchase, but during the entire period of use. Currently, for the aviation and aerospace industries, for the military-industrial complex, the reliability of products is of particular relevance. This article provides an overview of scientific achievements in the field of reliability of technical facilities and products. Of course, this review is not overall. However, the consideration reflects a significant part of books, monographs and other fundamental materials that have not lost their relevance to the present. The results of the study are a kind of guide to the labyrinth of the most difficult problems of solving reliability problems and methods that can be used to solve them.

Structural reliability analysis based on probability density evolution method and stepwise truncated variance reduction

To address the substantial computational burden associated with probability density evolution method (PDEM) in structural reliability analysis, this study proposes a novel look-ahead learning function named stepwise truncated variance reduction (STVR), integrating polynomial chaos Kriging (PCK) and PDEM. Three key features of STVR are highlighted. First, it enables quantifying the maximum reduction in predictive errors of PCK within the regions of interest (ROI) when adding a new point. Second, closed-form expression for STVR is derived through Kriging update formulas, eliminating the need for computationally intensive Gauss–Hermite quadrature or extensive conditional simulations of PCK. Third, a dynamic adjustment procedure is proposed for the probability level-related parameter in STVR, with the aim of achieving a good balance between the exploitation and exploration of ROI during the sequential experimental design process. The performance of STVR is demonstrated through two benchmark analytical functions and three numerical examples of varying complexity. Results indicate that the dynamic adjustment procedure for the probability level-related parameter in STVR outperforms the empirical setting of a minor value. Then, STVR proves more advantageous than existing pointwise and look-ahead learning functions, particularly in addressing complex dynamic reliability problems.