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This study aims to show the importance of natural convection of supercritical fluid in an inclined cavity. The heat transfer performance of natural convection can be improved.

A model of an inclined cavity was set up to simulate the natural convection of supercritical fluid. The influence of inclined angles (30 to approximately 90°) and pressures (8 to approximately 12 MPa) are analyzed. To ascertain flow and heat transfer of supercritical fluid natural convection, this paper conducts a numerical investigation using the lattice Boltzmann method (LBM), which is proven to be precise and convenient.

The results show that the higher heat transfer performance can be obtained with an inclined angle of 30°. It is also presented that the heat transfer performance under pressure of 10 MPa is the best. In addition, common criterion number correlations of average Nusselt number are also fitted.

These study results can provide a theoretical reference for the study of heat transfer of supercritical fluid natural convection in engineering.

The purpose of this paper is to show that the e‐derivative is of great significance when revealing cryptographic characteristics of Boolean functions and assurance of the safety of the cryptographic system.

A new definition is introduced in this paper.

After introducing the e‐derivative, the authors obtain some relevant cryptographic properties and theorems which can fully reveal the relationships between characteristics and structures of Boolean functions. In logic circuit fields, the authors conduct the test to all the signals with numerical value 1 in the transmission line using the e‐derivative, which improves the ability of the test. In addition, when there is no expression of the transmission line the authors will obtain it through the vector, and then do troubleshooting.

Logic circuit is the main limitation in the fault detection.

A very useful method for assurance of the safety of cryptographic systems.

This paper is the first time, in cryptology fields, that the e‐derivative of Boolean functions as a new definition is introduced to fully reveal the relationships between characteristics and structures of Boolean functions. In addition, they can also be applied to the locating test of the breakdown, which improves the ability of the test.

The purpose of this study is to attempt to explore how host governmental restriction and interfirm trust influence telecommunications operators (telcos) to choose international telecommunications alliance forms among equity alliances, relational alliances and recurrent alliances in three emerging markets: China, Hong Kong and Taiwan.

This study utilizes multiple discriminant analysis to analyze 111 international alliances established in China, Hong Kong and Taiwan during 1993-2004.

This study finds that host governmental restriction exerts greater influence on the choice of alliance form than interfirm trust. Telcos tend to develop non-equity alliances when governmental restriction is strong. In addition, they tend to develop equity and relational alliances when interfirm trust in high.

Two limitations are: this study only explores the impacts of a number of factors (host governmental restriction and interfirm trust) on alliance form choice, and it only focuses on bilateral alliances in telecommunications services industry. This study suggests that future study should explore other strategic factors (e.g. firms' capability, competitors' strategy) and multi-lateral alliances.

This study provides three managerial suggestions. First, when international telcos establish alliances in emerging markets, they should primarily evaluate host governmental restrictions, and second assess interfirm trust. In addition, if local telcos intend to build relational and equity alliances to acquire international telcos' technology and marketing know-how, they should enhance interfirm trust with them. Lastly, when host governments attempt to attract foreign equity investment, they should remove restrictions on foreign ownership and provide support and friendly regulatory institutions.

Most literature about telecommunications service industry focuses on developed markets and uses descriptive or case analysis. To fill these research gaps, this study conducts an empirical research by analyzing the international alliances in three emerging markets: China, Hong Kong and Taiwan. The findings not only provide suggestions to international telcos, local telcos and host governments in these markets but also can be applied to other emerging markets.

This study aims to investigate the relationships between radical innovation, market forces and political/business relationships in China by combining social capital theory and contingent theory. The paper focuses on how two types of managerial ties (i.e. business and political ties) impact firms’ capacity for radical innovation. It also examines the different moderating effects of market forces (i.e. demand uncertainty, technological turbulence and competitive intensity) on the linkage of managerial ties with radical innovation in the Chinese transitional context.

A systematic literature review on managerial ties, radical innovation and market forces in emerging markets provides the theoretical foundation of our conceptual model and hypothesis. Using a survey sample of 119 Chinese firms, the authors conduct a regression analysis on the theoretical model and hypotheses.

The results show that business ties have an inverted U-shape effect on radical innovation, while political ties have a positive impact on radical innovation. Furthermore, the market forces in transitional economies (i.e. demand uncertainty, technological turbulence and competitive intensity) have different moderating effects on the relationships between two types of managerial ties and Chinese firms’ radical innovation.

This study adopts its data set from the Chinese context. It would be necessary to replicate this research in other transitional economies because of specific differences between China and other transitional economies.

Findings from our study indicate that firms which wish to succeed in radical innovation may need to adapt their tie-based strategies according to different market settings.

The paper is original in its comparative investigation of the effect of business ties and political ties on radical innovation in contingent transitional market environments using a combination of social capital and contingent theories.

Scattered parts are laid randomly during the manufacturing process and have difficulty to recognize and manipulate. This study aims to complete the grasp of the scattered parts by a manipulator with a camera and learning method.

In this paper, a cascaded convolutional neural network (CNN) method for robotic grasping based on monocular vision and small data set of scattered parts is proposed. This method can be divided into three steps: object detection, monocular depth estimation and keypoint estimation. In the first stage, an object detection network is improved to effectively locate the candidate parts. Then, it contains a neural network structure and corresponding training method to learn and reason high-resolution input images to obtain depth estimation. The keypoint estimation in the third step is expressed as a cumulative form of multi-scale prediction from a network to use an red green blue depth (RGBD) map that is acquired from the object detection and depth map estimation. Finally, a grasping strategy is studied to achieve successful and continuous grasping. In the experiments, different workpieces are used to validate the proposed method. The best grasping success rate is more than 80%.

By using the CNN-based method to extract the key points of the scattered parts and calculating the possibility of grasp, the successful rate is increased.

This method and robotic systems can be used in picking and placing of most industrial automatic manufacturing or assembly processes.

Unlike standard parts, scattered parts are randomly laid and have difficulty recognizing and grasping for the robot. This study uses a cascaded CNN network to extract the keypoints of the scattered parts, which are also labeled with the possibility of successful grasping. Experiments are conducted to demonstrate the grasping of those scattered parts.

Traditional nondestructive failure localization techniques are increasingly difficult to meet the requirements of high density and integration of system in package (SIP) devices in terms of resolution and accuracy. Time domain reflection (TDR) is recognized as a novel positioning analysis technology gradually being used in the electronics industry because of the good compatibility, high accuracy and high efficiency. However, there are limited reports focus on the application of TDR technology to SiP devices.

In this study, the authors used the TDR technique to locate the failure of SiP devices, and the results showed that the TDR technique can accurately locate the cracking of internal solder joints of SiP devices.

The measured transmission rate of electromagnetic wave signal was 9.56 × 107 m/s in the experimental SiP devices. In addition, the TDR technique successfully located the failure point, which was mainly caused by the cracking of the solder joint at the edge of the SiP device after 1,500 thermal cycles.

TDR technology is creatively applied to SiP device failure location, and quantitative analysis is realized.

This paper aims to propose a soft actuator that combines a sponge-based actuating structure and a layer-jamming-based stiffness-improving structure in a cavity.

The proposed soft actuator consists of film-constrained sponge units (FCSUs) and jamming layers. The FCSUs in the proposed soft actuator bend under vacuum pressure, causing bending deformation of the entire actuator. The jamming layers are strongly coupled through friction under vacuum pressure, increasing the stiffness of the entire actuator. The performance of the proposed soft actuator was examined by measuring its stiffness, bending deformation and response performance. A four-finger soft robotic gripper was proposed based on the proposed soft actuator.

Through experiments, it was shown that the proposed soft actuator exhibited acceptable bending deformation, stiffness and response. Moreover, the proposed four-finger soft gripper could effectively grasp objects in daily life.

In this study, the authors proposed a novel bending actuator (with a volume of approximately 43.2 cm³) based on FCSUs and jamming layers. To the best of the authors’ knowledge, this is the first study to combine a sponge-based actuating structure and a layer-jamming structure in a cavity to achieve simultaneous change in actuation and stiffness. The soft actuator exhibited good bending deformation and high stiffness simultaneously under vacuum pressure. Consequently, it could be used effectively to fabricate soft grippers.

To ensure accurate position and force control of massage robot working on human body with unknown skin characteristics, this study aims to propose a novel intelligent impedance control system.

First, a skin dynamic model (SDM) is introduced to describe force-deformation on the human body as feed-forward for force control. Then a particle swarm optimization (PSO) method combined with graph-based knowledge transfer learning (GKT) is studied, which will effectively identify personalized skin parameters. Finally, a self-tuning impedance control strategy is designed to accommodate uncertainty of skin dynamics, system delay and signal noise exist in practical applications.

Compared with traditional least square method, genetic algorithm and other kinds of PSO methods, combination of PSO and GKT is validated using experimental data to improve the accuracy and convergence of identification results. The force control is effective, although there are contour errors, control delay and noise problems when the robot does massage on human body.

Integrating GKT into PSO identification algorithm, and designing an adaptive impedance control algorithm. As a result, the robot can understand textural and biological attributes of its surroundings and adapt its planning activities to carry out a stable and accurate force tracking control during dynamic contacts between a robot and a human.

This paper aims to investigate the distributed formation control problem for a multi-quadrotor unmanned aerial vehicle system without linear velocity feedbacks.

A nonlinear controller is proposed based on the orthogonal group SE(3) to obviate singularities and ambiguities of the traditional parameterized attitude representations. A cascade structure is applied in the distributed controller design. The inner loop is responsible for attitude control, and the outer loop is responsible for translational dynamics. To ensure a linear-velocity-free characteristic, some auxiliary variables are introduced to construct virtual signals in distributed controller design. The stability analysis of the proposed distributed control method by the Lyapunov function is provided as well.

A group of four quadrotors with constant reference linear velocity and a group of six quadrotors with varying reference linear velocity are adopted to verify the effectiveness of the proposed strategy.

This is a new innovation for multi-robot formation control method to improve assembly automation.