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Due to dynamic model is the basis of realizing various robot control functions, and it determines the robot control performance to a large extent, this paper aims to improve the accuracy of dynamic model for n-Degree of Freedom (DOF) serial robot.

This paper exploits a combination of the link dynamical system and the friction model to create robot dynamic behaviors. A practical approach to identify the nonlinear joint friction parameters including the slip properties in sliding phase and the stick characteristics in presliding phase is presented. Afterward, an adaptive variable-step moving average method is proposed to effectively reduce the noise impact on the collected data. Furthermore, a radial basis function neural network-based friction estimator for varying loads is trained to compensate the nonlinear effects of load on friction during robot joint moving.

Experiment validations are carried out on all the joints of a 6-DOF industrial robot. The experimental results of joint torque estimation demonstrate that the proposed strategy significantly improves the accuracy of the robot dynamic model, and the prediction effect of the proposed method is better than that of existing methods.

The proposed method extends the robot dynamic model with friction compensation, which includes the nonlinear effects of joint stick motion, joint sliding motion and load attached to the end-effector.

The purpose of this paper is to quickly manufacture full Cu₃Sn-microporous copper composite joints for high-temperature power electronics applications and study the microstructure evolution and the shear strength of Cu₃Sn at different bonding times.

In this paper, a novel structure of Cu/composite solder sheet/Cu was designed. The composite solder sheet was made of microporous copper filled with Sn. The composite joint was bonded by thermo-compression bonding under pressure of 0.6 MPa at 300°C. The microstructure evolution and the growth behavior of Cu₃Sn at different bonding times were observed by electron microscope and metallographic microscope. The shear strength of the joint was measured by shear machine.

At initial bonding stage the copper atoms in the substrate and the copper atoms in the microporous copper dissolved into the liquid Sn. Then the scallop-liked Cu₆Sn₅ phases formed at the interface of liquid Sn/microporous copper and liquid Sn/Cu substrates. During the liquid Sn changing to Cu₆Sn₅ phases, Cu₃Sn phases formed and grew at the interface of Cu₆Sn₅/Cu substrates and Cu₆Sn₅/microporous copper. After that the Cu₃Sn phases continued to grow and the Cu₃Sn-microporous copper composite joint with a thickness of 100 µm was successfully obtained. The growth rule of Cu₃Sn was parabolic growth. The shear strength of the composite joints was about 155 MPa.

This paper presents a novel full Cu₃Sn-microporous copper composite joint with high shear strength for high-temperature applications based on transient liquid phase bonding. The microstructure evolution and the growth behavior of Cu₃Sn in the composite joints were studied. The shear strength and the fracture mechanism of the composite joints were studied.

Human-induced marine environmental noise, such as commercial shipping and seismic exploration, is concentrated in the low-frequency range. Meanwhile, low-frequency sound signals can achieve long-distance propagation in water. To meet the requirements of long-distance underwater detection and communication, this paper aims to propose an micro-electro-mechanical system (MEMS) flexible conformal hydrophone for low-frequency underwater acoustic signals. The substrate of the proposed hydrophone is polyimide, with silicon as the piezoresistive unit.

This paper proposes a MEMS heterojunction integration process for preparing flexible conformal hydrophones. In addition, sensors prepared based on this process are non-contact flexible sensors that can detect weak signals or small deformations.

The experimental results indicate that making devices with this process cannot only achieve heterogeneous integration of silicon film, metal wire and polyimide, but also allow for customized positions of the silicon film as needed. The success rate of silicon film transfer printing is over 95%. When a stress of 1 Pa is applied on the x-axis or y-axis, the maximum stress on Si as a pie-zoresistive material is above, and the average stress on the Si film is around.

The flexible conformal vector hydrophone prepared by heterogeneous integration technology provides ideas for underwater acoustic communication and signal acquisition of biomimetic flexible robotic fish.

This paper aims to develop a resonant accelerometer for structure optimization. The dynamic analysis of the resonator for resonant accelerometer are investigated.

First, the working principle and mechanical model of the resonator are introduced. Moreover, dynamic analysis of the resonator is used for the purpose of investigating the dynamic characteristics of the resonant accelerometer. Finally, to verify the feasibility of the proposed dynamic analysis method, resonant accelerometer 1g static tumbling experiments of resonant accelerometer are built.

It can be seen from the natural frequency and the resonator mode that only when the resonator root stiffness is much greater than the resonant beam stiffness, there will be appear corresponding interference mode, therefore,the resonator root stiffness is avoid too large in design. The stability analysis result of resonant beam under axial force show that the resonant beam parameters should be maintained a constant. At the same time, it is concluded from the vibration mode analysis for resonant beam that the influence of the beam thickness and beam errors on the first and second order modes is great. On the other hand, it is concluded from the test result that the designed resonant accelerometer sensitivity is 98 Hz/g, which shows that the dynamic analysis method is feasible.

The research may be significant in the field of resonant sensors, supporting a variety of practical applications such as phone and game.

This paper seeks to establish a foundation for designing and optimizing resonant accelerometer structure. To this end, the dynamic analytical method of the resonator for resonant accelerometer was discussed. The results of this research have proved that the dynamic analysis based on a resonator is an effective approach and instructional in practical resonant sensor design.

Selective laser sintering (SLS) is an essential technology in the field of additive manufacturing. However, SLS technology is limited by the traditional point-laser sintering method and has reached the bottleneck of efficiency improvement. This study aims to develop an image-shaped laser sintering (ISLS) system based on a digital micromirror device (DMD) to address this problem. The ISLS system uses an image-shaped laser light source with a size of 16 mm × 25.6 mm instead of the traditional SLS point-laser light source.

The ISLS system achieves large-area image-shaped sintering of polymer powder materials by moving the laser light source continuously in the x-direction and updating the sintering pattern synchronously, as well as by overlapping the splicing of adjacent sintering areas in the y-direction. A low-cost composite powder suitable for the ISLS system was prepared using polyether sulfone (PES), pinewood and carbon black (CB) powders as raw materials. Large-sized samples were fabricated using composite powder, and the microstructure, dimensional accuracy, geometric deviation, density, mechanical properties and feasible feature sizes were evaluated.

The experimental results demonstrate that the ISLS system is feasible and can print large-sized parts with good dimensional accuracy, acceptable geometric deviations, specific small-scale features and certain density and mechanical properties.

This study has achieved the transition from traditional point sintering mode to image-shaped surface sintering mode. It has provided a new approach to enhance the system performance of traditional SLS.

Given the scarcity of data during the early stages of the COVID-19 pandemic in China, the decision-making for non-pharmaceutical policies was mostly based on insufficient evidence. The purpose of this study is to assess the effectiveness of these policies, such as lockdown and government subsidies, on rural households and identify policy implications for China and other countries in dealing with pandemics.

The authors survey 2,408 rural households by telephone from 101 counties across 17 provinces in China during the first stage of the pandemic (March 2020). The authors use the ordered probit model and linear regression model to study the overall impact of policies and then use the quantile regression model and sub-sample regression method to study the heterogeneity of the effects of government policies.

The authors find that logistics disruption due to lockdown negatively affected rural households. Obstructed logistics is associated with a more significant loss for high-income households, while its impact on the loss expectation of low-income households is more severe. Breeding and other industries such as transport and sales suffer more from logistics than cultivation. The impact of logistics on intensive agricultural entities is more serious than that on professional farms. The government subsidy is more effective at reducing loss for low-income households. Lockdown and government subsidies have shown heterogeneous impacts on rural households.

The overall economic losses experienced by rural households in the early stages of the pandemic are controllable. The government policies of logistics and subsidies should target specific groups.

The authors evaluate the economic impacts of lockdown and government subsidies on rural households and show their heterogeneity among different groups. The authors further demonstrate the policy effectiveness in supporting rural households during the early stages of the pandemic and provide future policy guidance on major public health event.

The operation of water environment treatment Public-Private Partnership projects (WETP-PPP) is crucial to the project effectiveness. However, there are often problems in projects that attach importance to construction and neglect operation management, which seriously affect the project operation effect. To ensure the good operation effect of the WETP-PPP, an evolutionary game model of the regulation strategy during the operation period of WETP-PPP is constructed.

An evolutionary game model of regulation is established which considers the government, the project company and the public in water environment treatment Public-Private Partnership projects (WETP-PPP). Five scenarios of equilibriums and the game's evolutionary stable strategies are analyzed, and the corresponding stability conditions are then obtained. Finally, through the simulation, the influence of different factors on the choice of the three-party strategy is analyzed.

First, the key factors that affect the evolution game are the regulation costs and performance rewards of the government, the project company's operation costs and penalties for opportunism and the public supervision costs and rewards. Second, in order to ensure the operation effect, the government needs the performance incentive from the superior government. Third, the public's supervision enthusiasm needs to be mobilized by the government. Last, the penalty strength of speculative operation should be strong enough to play a deterrent role.

The theoretical research in this paper has some limitations. Initially, due to the large number of participants in WETP-PPP, in addition to the government department, the project company and the public studied in this paper, it also involves the consulting industry and financial institutions. In the future, more participants can be added to form four-party interest relationships and conduct four-party evolutionary game research. Second, the operation environment of WETP-PPP is complex and changeable, and various influencing factors are intertwined, the number of parameters involved in this paper is limited, and further detailed research is needed in the future.

Based on the evolutionary game theory, this article discusses the evolution law of the tripartite game behavior of the government department, the project company and the public, which is helpful to clarify the strategy evolution path of the tripartite in the WETP-PPP, and the generation condition and evolution mechanism of the equilibrium strategy of the tripartite game. The key parameters affecting the tripartite strategy selection are analyzed through simulation, which can provide reference for the government department to formulate relevant measures. At the same time, it broadens the application field of evolutionary games and supplements the research on the management mechanism of WETP-PPP during the operation period.

Based on the evolutionary game theory, this paper introduces the supervision behavior of the public, which can provide a new perspective for researchers to conduct relevant research. Secondly, for the regulation during the operation of WETP-PPP, this paper can provide reference for the government department to establish a scientific public supervision system, improve the government supervision mechanism and other relevant measures, which can help promote the public supervision willingness, improve the regulation efficiency of the government and guide the project company to reduce speculation, so as to ensure the effect of water environment management.

This paper focuses on the regulation of WETP-PPP during the operation period to research interactions among the government, the project company and the public. Based on the analysis of the evolutionary game, some suggestions are put forward, such as perfecting the government regulation mechanism, optimizing the reward and punishment system for the project company and broadening the channels of public supervision. The research results of this paper can provide support for the government's regulation of WETP-PPP and ensure the project operation effect.

This paper aims to focus on establishing the bond-slip constitutive relation of mortar anchor under high loading rates by the dynamic pull-out test.

Self-made specimens were made for the dynamic pull-out test to explore the bond performance of mortar anchor, and the bond-slip constitutive relation of mortar anchor under high loading rates was established according to the analysis of test data.

During the loading process, the position of the peak bond stress was observed to translate to the free end. The bearing capacity of the mortar anchor was enhanced to some extent due to the increase of the loading rate.

The bond-slip constitutive relation of mortar anchor under high loading rates was established with the introduction of the position function and dynamic-load expanded coefficient.

Human resource practices are transforming at a varying pace for different businesses to meet the increasingly intensified external challenges. The pursuit of innovation while balancing the tensions between flexibility and efficiency has become a core challenge for survival in this globally competitive era. The literature identifies ambidexterity as a realistic choice to manage these tensions during transformation towards diversified and innovative human resource practices. Based on social exchange theory (SET), this study explores the impact of ambidextrous human resource practices (AHRPs) on organization members' innovation performance while examining the mediating effect of psychological safety.

Data were collected for this cross-sectional study in three waves, and the final sample included 788 employees from 32 companies across different industries in China.

The results of data analysis indicate support for all the hypothesized relationships. AHRPs positively affect employee innovation performance; employee psychological safety mediates this relationship; inclusive leadership moderates the direct effect of AHRPs on employee psychological safety and the indirect effect of AHRPs on employee innovative performance through psychological safety. Theoretical and practical implications of the study are also presented.

This study examines AHRPs’ influence on employee innovation performance mediated by psychological safety and the moderating role of inclusive leadership in the above relationship to clarify the boundary conditions of AHRPs' effect on innovation performance.

The Sports Live Streaming Platforms (SLSPs) have taken centre stage in broadcasting sporting events. This study adopts the value creation sphere (VCS) model and the service dominant logic (SDL) to unpack the value co-creation process on SLSPs.

A case study with one of the most representative SLSPs in China, involving the netnographic approach and in-depth interviews, was conducted.

This study redefines the value co-creation spheres in the context of SLSPs and identifies four actors who contribute to viewers' value perceptions. The findings show that viewers' values can be co-created individually and collectively with other actors in both the customer sphere and the joint sphere.

This study extends the theoretical boundary of value co-creation into the context of SLSPs. The study findings help SLSPs managers and decision makers understand the value co-creation process to gain competitive advantages and enhance the sustainability of their services.