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The purpose of this paper is to clarify the method of using RF impedance changes as an early indicator of degradation of solder joint. It proposes the mode of crack propagation in solder joint and outlines why RF impedance analysis can be capable of detecting small cracks. The study aims to show the potential of RF impedance analysis as a prognostic tool that can provide advanced warning of impending failures of solder joint.

In this paper, the mode of crack propagation in solder joint was studied to show why RF impedance analysis could be capable of detecting small cracks. A real simple impedance‐controlled test vehicle was developed to allow RF impedance and DC resistance measurements to monitor solder joint degradation. The influence of crack length on RF impedance was evaluated by high frequency structure simulator (HFSS) simulation for the first time.

The paper demonstrates that RF resistance can respond to an open state of a solder joint as well as DC resistance. Furthermore, RF impedance can monitor partial degradation of solder joints, while the DC resistance cannot do it. In addition, time‐domain reflection coefficient is found to be more useful than RF impedance in detecting solder joint degradation. The HFSS simulation results show that even very slight physical degradation of solder joints can be detected using RF impedance analysis.

In this paper, HFSS simulation is used for the first time to evaluate the influence of crack length on RF impedance.

The purpose of this study is to examine how the quality management of small and medium-sized enterprises (SMEs) impacts their supply chain financing performance (SCFP). This study also investigates the mediating roles of organisational dependence between quality management and the SCFP of SMEs, as well as the moderating role of environmental dynamics.

Questionnaires were administered to 248 financial managers responsible for supply chain finance (SCF) in SMEs in China. Data analysis techniques used include necessary condition analysis and multiple regression analysis.

Research findings show that, in SCF, the quality management of SMEs positively predicts their SCFP through the mediation of the organisational dependence of the focal enterprises in the supply chain network. Environmental dynamics are also found to moderate the relationship between quality management and SCFP through the organisational dependence of capital providers.

To the best of our knowledge, this is the first study to explore the relationships between SMEs' quality management and their SCFP. Also, this study provides a new theoretical lens through which to study SCF by introducing signalling theory.

As wheeled mobile robots find increasing use in outdoor applications, it becomes more important to reduce energy consumption to perform more missions efficiently with limit energy supply. The purpose of this paper is to survey the current state-of-the-art on energy-efficient motion planning (EEMP) for wheeled mobile robots.

The use of wheeled mobile robots has been increased to replace humans in performing risky missions in outdoor applications, and the requirement of motion planning with efficient energy consumption is necessary. This study analyses a lot of motion planning technologies in terms of energy efficiency for wheeled mobile robots from 2000 to present. The dynamic constraints play a key role in EEMP problem, which derive the power model related to energy consumption. The surveyed approaches differ in the used steering mechanisms for wheeled mobile robots, in assumptions on the structure of the environment and in computational requirements. The comparison among different EEMP methods is proposed in optimal, computation time and completeness.

According to lots of literature in EEMP problem, the research results can be roughly divided into online real-time optimization and offline optimization. The energy consumption is considered during online real-time optimization, which is computationally expensive and time-consuming. The energy consumption model is used to evaluate the candidate motions offline and to obtain the optimal energy consumption motion. Sometimes, this optimization method may cause local minimal problem and even fail to track. Therefore, integrating the energy consumption model into the online motion planning will be the research trend of EEMP problem, and more comprehensive approach to EEMP problem is presented.

EEMP is closely related to robot’s dynamic constraints. This paper mainly surveyed in EEMP problem for differential steered, Ackermann-steered, skid-steered and omni-directional steered robots. Other steering mechanisms of wheeled mobile robots are not discussed in this study.

The survey of performance of various EEMP serves as a reference for robots with different steering mechanisms using in special scenarios.

This paper analyses a lot of motion planning technologies in terms of energy efficiency for wheeled mobile robots from 2000 to present.

In this article, the elementary notions and aggregation operations of single-valued neutrosophic parameterized complex fuzzy hypersoft set (sv-NPCFHSS) are characterized initially. Then by using matrix version of sv-NPCFHSS, a decision-support system is constructed for the evaluation of real estate residential projects by observing various risk factors.

Two approaches are utilized in this research: set-theoretic approach and algorithmic approach. The first approach is used to investigate the notions of sv-NPCFHSS and its some aggregations whereas the second approach is used to propose an algorithm for designing its decision-support system by using the aggregation operations like reduced fuzzy matrix, decision matrix, etc. of sv-NPCFHSS. The adopted algorithm is validated in real estate scenario for the selection of residential project by observing various risk factors to avoid any expected investment loss.

The proposed approach is more flexible and reliable as it copes with the shortcomings of literature on sv-neutrosophic set, sv-neutrosophic soft set and other fuzzy soft set-like structures by considering hypersoft setting, complex setting and neutrosophic setting collectively.

It has limitations for complex intuitionistic fuzzy hypersoft set, complex neutrosophic hypersoft set and other complex neutrosophic hypersoft set-like models.

The scope of this research may cover a wide range of applications in several fields of mathematical sciences like artificial intelligence, optimization, MCDM, theoretical computer science, soft computing, mathematical statistics etc.

The proposed model bears the characteristics of most of the relevant existing fuzzy soft set-like models collectively and fulfills their limitations.

The purpose of this paper is to study the preload range of tendon-driven manipulator and the relationship between preload and damping. The flexible joint manipulator (FJM) with joint flexibility is safer than traditional rigid manipulators. A FJM having an elastic tendon is called an elastic tendon-driven manipulator (ETDM) and has the advantages of being driven by a cable and having a more flexible joint. However, the elastic tendon introduces greater residual vibration, which makes the control of the manipulator more difficult. Accurate dynamic modeling is effective in solving this problem.

The present paper derives the relationship between the preload of the ETDM and the friction moment through the analysis of the forces of cables and pulleys. A dynamic model dominated by Coulomb damping is established.

The linear relationship between a decrease in the damping moment of the system and an increase in the ETDM preload is verified by mechanics analysis and experiment, and a curve of the relationship is obtained. This study provides a reference for the selection of ETDM preload.

The method to identify ETDM damping by vibration attenuation experiments is proposed, which is helpful to obtain a more accurate dynamic model of the system and to achieve accurate control and residual vibration suppression of ETDM.

Employing big data analysis tools, this study examines the significance of supply chain integration affecting online financial consumption, analyzes the online financial consumption demand of mobile phone consumers, promotes the optimization of supply chain services with consumers as the focus and proposes full integration of a mobile phone supply chain in terms of product, logistics and marketing, in order to improve the supply and demand relationship between consumers and suppliers; the overall objective is to promote further development of online financial consumption.

In this study, TF-IDF (term frequency–inverse document frequency) and cosine similarity text analysis are used for analyzing online demand for mobile phone products, studying the influence of supply chain services on consumption demand and identifying strategies for promoting overall optimization of the supply chain to meet online financial consumption demands of consumers; the study analyzes online reviews on mobile phone topics from the JingDong (JD) platform and Weibo platform.

Research results show that online demand for mobile phone products is greatly influenced by supply chain links such as product design, logistics transportation and marketing promotion. The consumption demand for different mobile phone products has different emphases, but the differences are not significant. The overall improvement of the supply chain should focus on product research and development, logistics layout optimization and marketing promotion, in order to meet and guide the online financial demand of consumers and improve the effectiveness of supply chain management.

This study only considered data from China's largest online mobile phone sales platform and Weibo text data owing to the data sensitivity involved.

There are few supply chain optimization studies based on online financial consumption reviews from customers. Therefore, this study integrates online consumption trends into a supply chain analysis framework to explore strategies for promoting supply chain optimization according to customer demands, improving the benign interaction of participants in the supply chain and promoting the development of online financial consumption.

This paper aims to propose a boundary element analysis of two-dimensional linear elasticity problems by a new expanding element interpolation method.

The expanding element is made up based on a traditional discontinuous element by adding virtual nodes along the perimeter of the element. The internal nodes of the original discontinuous element are referred to as source nodes and its shape function as raw shape function. The shape functions of the expanding element constructed on both source nodes and virtual nodes are referred as fine shape functions. Boundary variables are interpolated by the fine shape functions, while the boundary integral equations are collocated on source nodes.

The expanding element inherits the advantages of both the continuous and discontinuous elements while overcomes their disadvantages. The polynomial order of fine shape functions of the expanding elements increases by two compared with their corresponding raw shape functions, while the expanding elements still keep independence to each other as the original discontinuous elements. This feature makes the expanding elements able to naturally and accurately interpolate both continuous and discontinuous fields.

Numerical examples are presented to verify the proposed method. Results have demonstrated that the accuracy, efficiency and convergence rate of the expanding element method.

Currently, China’s economy is in the critical phase of transforming economic development patterns and replacing old growth drivers with new ones. Whether it can successfully overcome the “middle-income trap” has become a significant issue attracting wide attention.

Driven by underlying digital technologies such as artificial intelligence, blockchain, cloud computing and big data, the fourth industrial revolution featuring the booming digital economy has provided significant opportunities for China’s economy to “overtake” and overcome the “middle-income trap”. The transformation of economic development pattern, the optimization of industrial structure, and the change of growth drivers, brought by the deep integration of digital and real economies are the keys to leaping over the “middle-income trap”.

From the supply side, the digital economy can improve the quality and efficiency of the supply side and promote the supply-side structural reform and economic growth from the following three aspects: First, promote the quality, efficiency and diversification of the supply system; second, promote networking, opening-up and synergy in the innovation system and third, promote the socialization, modularization and flexibility of production pattern. From the demand side, the digital economy can boost the new drivers of the “troika” of economic growth consisting of consumption, exports and investment by changing the market investment direction, promoting consumption upgrade and fostering export strengths. However, once these two attributes interact with each other, especially when data is combined with capital, the most adhesive factor in the market economy, a series of new social relations will then be produced based on the technical attribute, resulting in significant adjustments in social relations, involving both positive and negative externalities.

To overcome the “middle-income trap”, it is necessary to adapt to the laws of economic evolution and promote a fundamental change in economic growth drivers; boost the high-quality development of the digital economy by strengthening the support role of data in the digital economy; and accelerate digital industrialization and industrial digitalization to realize the integration of digital and real economies.

The purpose of this paper is to present an adaptive binary-tree element subdivision method (BTSM) for the evaluation of nearly singular integrals in three-dimensional boundary element method, which can facilitate automatic and high-quality patch generation.

In this method, the nearly singular element is split into two sub-elements. Each sub-element is then examined to determine if it is to be subdivided based on a specific subdivision criterion. The specific subdivision ensures that those sub-elements far from the source point are sparse. And then those sub-elements in close proximity to the source point are replaced by regular triangular elements.

With the proposed method, the sub-elements obtained are automatically refined as they approach the projection point, and they are “good” in shape and size for standard Gaussian quadrature. Thus, the proposed method can be used to evaluate nearly singular integrals accurately for cases of different element shapes and various locations of the source point.

Numerical examples for surface elements with various relative locations of the source point are presented. The results demonstrate that the proposed method has much better accuracy and robustness than some other methods.

The Convolution Quadrature Method (CQM) has been widely applied to solve transient elastodynamic problems because of its stability and generality. However, the CQM suffers from the problems of huge memory requirement in case of direct implementation in time domain or CPU time in case of its reformulation in Laplace domain. The purpose of this paper is to combine the CQM with the pseudo-initial condition method (PICM) to achieve a good balance between memory requirement and CPU time.

The combined methods first subdivide the whole analysis into a few sub-analyses, which is dealt with the PICM, namely, the results obtained by previous sub-analysis are used as the initial conditions for the next sub-analysis. In each sub-analysis, the time interval is further discretized into a number of sub-steps and dealt with the CQM. For non-zero initial conditions, the pseudo-force method is used to transform them into equivalent body forces. The boundary face method is employed in the numerical implementation. Three examples are analyzed. Results are compared with analytical solutions or FEM results and the results of reformulated CQM.

Results demonstrate that the computation time and the storage requirement can be reduced significantly as compared to the CQM, by using the combined approach.

The combined methods can be successfully applied to the problems of long-time dynamic response, which requires a large amount of computer memory when CQM is applied, while preserving the CQM stability. If the number of time steps is high, then the accuracy of the proposed approach can be deteriorated because of the pseudo-force method.