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The purpose of this study aims to modify a self-mixing laser mouse as an extremely cost-effective displacement sensor to measure the mechanical oscillation of a commercial shaker and a nano-positioning stage.

This kind of laser mouse, mostly consisting of a pair of vertical cavity surface emitting lasers, two photodiodes and an integrated signal processing unit, is capable of directly giving the x-axis and y-axis components of the measured vibrating displacement. Based on the laser self-mixing interference, the velocity of the object is coded into the Doppler frequency shift of the feedback light, which allows accurate determination of the vibration of the object.

A commercial shaker has been used to provide standard harmonic oscillation to test the displacement sensor. Within a vibrating frequency range of 110 Hz, the experimental results show that the micrometer scale resolution has been achieved at the velocity of up to 2 m/s, which is much improved compared with the image-based optical mouse. Furthermore, the measurements of the two dimensional displacement of a nano-positioning stage are performed as well. The minimum measurable velocity limit for this sensor has been discussed in detail, and the relative measurement error can be greatly reduced by appropriate selection of the modulation frequency of the triangular injection current.

These results demonstrate the feasibility of this device for the industrial vibration sensing applications.

The electrical properties of piezoelectric vibrators have a crucial influence on the operating state of ultrasonic motors. In order to solve the problem that the current piezoelectric vibrator generates a large amount of heat during vibration to degrade its performance, which in turn affects the normal operation of ultrasonic motors, this paper prepares a novel piezoelectric vibrator and tests its maximum vibration velocity under the working condition, which is more than twice as much as that of the current commercial PZT-8.

The crystal structures of the samples were analyzed by using an X-ray diffractometer. For microstructure observation, samples were observed by scanning electron microscope (SEM). The quasi-static piezoelectric coefficient meter (ZJ-3AN) was used for piezoelectric measurement. Dielectric properties were measured by utilizing an impedance analyzer (Agilent 4294A) with a laboratory heating unit. Ferroelectric hysteresis loops were obtained using a ferroelectric analyzer (Radiant, Multiferroic 100). A Doppler laser vibrometer (Polytec PSV-300F, Germany) and a power amplifier were used for piezoelectric vibration measurements, during which the temperature rise was determined by an infrared radiation thermometer (Victor 303, China).

The ceramics exhibit enhanced piezoelectric performance at 0.1–0.4 mol% of Yb doping contents. The ceramic of 0.4 mol% Yb reaches the maximal internal bias field and presents a larger mechanical quality factor of 1,692 compared with that of 0.2 mol% Yb-doped ceramic, in spite of a slightly decreased dielectric constant of 439 pC/N, the unit of the piezoelectric constant, which is the ratio of the local charge (pC) to the frontal force (N) and electromechanical coupling coefficient of 0.63. The vibrator with this large mechanical quality factor ceramic displays a vibration velocity of up to 0.81 m/s under the constraint of 20 °C temperature rising, which is much higher than commercial high-power piezoelectric ceramics PZT-8.

The enhanced high-power properties of the piezoelectric vibrator by Yb doping may provide a potential application for the high-performance USM and offer the possibility of long-term stable operation under high power for special equipment like USM. In the subsequent phase of research, the novel PZT-based high-power piezoelectric vibrator can be utilized in the USM, and the motor's performance will be evaluated under aerospace conditions to objectively assess the reliability of the piezoelectric vibrator.

With the rapid increase in the number of installed wind turbines (WTs) worldwide, requirements and expenses of maintenance have also increased significantly. The condition monitoring (CM) of WT provides a strong “soft guarantee” for preventive maintenance. The supervisory control and data acquisition (SCADA) system records a huge amount of condition data, which has become an effective means of CM. The main objective of the present study is to summarize the application of SCADA data to fault detection in wind turbines, analyze its advantages and disadvantages and predict the potential of future investigations on the use of SCADA data for fault detection.

The authors first review the means of WT CM and summarize the characteristics of CM based on SCADA data. To ensure the quality of SCADA data, data preprocessing methods are analyzed and compared. Then, the failure modes of the key components are discussed and the SCADA data used for fault detection of each component are compared. Moreover, the fault detection methods for WT are classified and a general framework for fault detection is proposed. Finally, the issues in the WT fault detection method based on SCADA data are reviewed.

Based on the performed analyses, it is found that although the fault detection accuracy based on SCADA data is relatively poor, it has low capital expenses and low computational cost. More specifically, when there is scarce fault data, the normal SCADA data can be used to detect the fault time. However, the specific fault type cannot be identified in this way. When a large amount of fault data are accumulated in the SCADA system, it can not only detect the occurrence time of the fault but also identify the specific fault type.

The main contribution of the present study is to summarize the pre-processing methods for SCADA data, the data required for fault detection of key components and the characteristics of the fault detection model. Then we propose a general fault detection framework for wind turbines based on SCADA data, where the maintenance workers can choose the appropriate fault detection method according to different fault detection requirements and data resources. This article is expected to provide guidance for fault detection based on time-series sensor signals and be of interest to researchers, maintenance workers and managers.

This paper aims to present the evolution of Chinese business ethics and CSR policy. China currently has business ethics and corporate social responsibility (CSR) concerns primarily because its economy is in evolution. As the Chinese economy is in transition from the late 1970s from a command–Communist economy to a more hybrid system Beijing model (a system based on a capitalist market controlled through bureaucracy), much has to be understood if one wants to participate in its vast economic potential.

The study is based on the building of a model that depicts the evolution of business ethics in China as a base for further research.

With the rapid development of the Chinese economy, opportunities are opening up to Chinese entrepreneurs and connected officials. This has led to money worship and, in some cases, thorough unethical behavior. The uncertain and ever-changing rules of the game generate opportunity for business ethics and CSR problems. This wealth creates temptation and incentives to cut corners to get rich fast. Much research has tried to explain business ethics in China through the understanding of Guanxi (Chinese social network of reciprocal business relations common in Confucian cultures), but in my view, the evolutionary aspect of it is missing to explain the present and future situation. Whereas considerable research has dealt with the growth of Chinese industries in recent years, the key relationship between changes in its economy and shifts in Chinese business ethics has been neglected. This paper presents the evolution of Chinese business ethics and CSR policy.

The paper illustrates the evolution of Chinese business ethics and how one has to adapt if one wants to succeed in its ever evolving and maturing market. A model is presented that can assist in future research in the area.

Cemented conglomerate accumulation is a weak and heterogeneous medium that occurs in western China. It consists mainly of argillaceous cement that loses strength rapidly upon contact with water, leading to collapse instability failure. Its deformation failure mechanism is complex and poorly understood. In this paper, the erosion failure mechanism of cemented conglomerate accumulation is investigated.

The collapse failure process after erosion of the slope foot for typical cemented conglomerate accumulation is studied based on field investigation using the particle discrete element method. And how the medium composition, slope angle and cementation degree influence the failure mode and process of the cemented conglomerate accumulation is examined.

The foot erosion of slope induces a tensile failure that typically manifests as “erosion at the foot of slope – tensile cracking at the back edge of slope top – integral collapse.” The collapse failure is more likely to occur when the cemented conglomerate accumulation has a higher rock content, a steeper slope angle or a weaker cementation degree.

A model based on rigid blocks and disk particles to simulate the cemented conglomerate accumulation is developed. It shows that the hydraulic erosion at the foot of the slope resulted in a different failure mechanism than that of general slopes. The results can inform the stability management, disaster prevention and mitigation of similar slopes.

Financial technologies, also known as “FinTech,” have brought disruptive changes to virtually every aspect of financial services and are becoming increasingly important in the world economic system. The purpose of this paper is to proffer a bird view of some recent studies in the key research areas of FinTech, such as artificial intelligence, blockchain, crowdfunding and then to summarize the key contributions made by all the six papers in this special issue.

A literature review approach is adopted, and the summary shows that most types of FinTech innovations generate positive value to innovators, financial customers and the society. The current implications and future directions are explored based on theoretical and empirical analyses.

The benefits from and determinants of FinTech applications vary across different financial sectors. Together the summary of this special issue suggests that there is substantial value creation in further exploring the dynamics, mechanisms and social consequences of FinTech.

This study helps to extend knowledge by summarizing the current practices, proffering new insights and watching out emerging trends of financial technologies, and to shed light on a variety of subjects of interest to practitioners, academics and policy makers by suggesting for the future research topics.

The purpose of this paper is to identify the solder joint with optimal mechanical properties among Cu/Sn/Cu, Ni/Sn/Ni and Cu/Sn/Ni solder joints.

Solder joints with the same specimen shape were prepared by reflow. The microstructures were observed and analyzed by scanning electron microscopy and tensile testing was carried out to investigate the mechanical properties.

The mechanical properties of solder joint correlate closely with the intermetallic compounds (IMC) layer structure and the dissociative IMC particles in the solder bulk. Under the influence of the opposite Cu bar, the Cu/Sn/Ni has a duplex IMC layer structure at the Ni side, involving a thin Ni‐Cu‐Sn IMC layer and a faceted (Cu,Ni)₆Sn₅ layer. The mechanical connection of the duplex IMC layers is weak due to the pores in the layers. The Cu/Sn/Ni fractures in the IMC layers in a brittle mode under tensile testing. Comparatively, the Ni/Sn/Ni also has duplex Ni₃Sn₄ layers, and they connect firmly with each other. The tensile fracture of the Ni/Sn/Ni occurs in the solder bulk in a ductile mode, as well as for the Cu/Sn/Cu. Compared with the Cu/Sn/Cu solder bulk, the solder bulk of the Ni/Sn/Ni and the Cu/Sn/Ni have higher ultimate tensile strengths, because the strengthening effect of the dissociative Ni₃Sn₄ and (Cu,Ni)₆Sn₅ particles on the solder bulk is stronger than that of the Cu₆Sn₅ particles. Among Cu/Sn/Cu, Ni/Sn/Ni and Cu/Sn/Ni, Ni/Sn/Ni has the optimal mechanical properties.

The paper offers insights into the significant influence of base material matching on the microstructure and mechanical properties of solder joints.

The purpose of this paper is to adopt rapid prototyping (RP) technology to fabricate self‐hardening calcium phosphate composite (CPC) scaffolds with a controlled internal channel network to facilitate nutrient supplying and cell growth using RP technique and investigate their in vitro performance.

Porous scaffolds should possess branched channels to ensure uniform cell feeding and even flow of culture medium to promote uniform cell attachment and growth. A new three dimensional (3D) flow channel structure has been designed based on conversation of energy and flow. The CPC scaffold possessing such a channel network was made by indirect solid free form fabrication. Negative model of scaffold was designed by Pro/E software and its epoxy resin mold was fabricated on a sterolithography apparatus and the CPC slurry was filled in these molds. After CPC was self hardened, the mold was baked. The mold was removed by pyrolysis and then the designed scaffold was obtained.

The sizes of the fabricated scaffolds were consistent with the designed. The average compressive strength of the scaffold is approximately 6.0 MPa. Computational fluid dynamics and perfusion culture results showed that such a 3D flow channel arrangement would lead to a more uniform distribution of flow and cells and good transportation of nutrients.

The size errors of fabricated scaffolds could not escape and perfusion methods were difficult to control.

The basic design concept presented showed great promise for use in bone tissue engineering and fabrication method enhanced the versatility of scaffold fabrication. The designed scaffold structure made it possible to keep integrality of the scaffold when direct observation cells inside the channel by scanning electron microscopy (SEM).

This paper aims to investigate the effect of Cu content and T6 heat treatment on the mechanical properties and the tribological performance of SiCp/Al-Si-Cu-Ni-Mg hybrid composites at an elevated temperature.

The stir casting method was used to synthesize SiCp/Al-12Si-xCu-1Ni-1Mg (x = 2, 3, 3.5, 4, 4.5, 5 Wt.%) composites containing 20 vol% SiC. The hardness and tensile strength of the aluminum matrix composites (AMCs) at room temperature and elevated temperature were studied, and the wear mechanism was investigated using scanning electron microscopic and energy dispersive spectroscopy.

Results indicate that the hardness and tensile strength of the AMCs are affected significantly by T6 heat treatment and Cu content. The high-temperature friction and wear mechanism of AMCs is the composite wear mechanism of oxidation wear, adhesion wear, abrasive wear, peeling wear, high-temperature softening and partial melting. Among them, adhesion wear, high-temperature matrix softening and local melting are the main wear mechanisms.

The influence mechanism of Cu content on the hardness, tensile strength and high temperature resistance of AMCs was explained by microstructure. And the results further help to explore the application of AMCs in high temperature.