QUALITY DESIGN OF TAGUCHI’S DIGITAL DYNAMIC SYSTEMS

Taguchi’s method is a widely employed methodology in many different industries for improving product quality and process performance. Digital dynamic systems denote the problems where both the input and output are digital values in Taguchi’s method. When the signal factor levels are classified into two classes and the output is classified into two or more classes, two or more errors will occur in experiments. The digital dynamic systems are widely applied in the fields of telecommunication, computer operations, chemistry and tests of detection of medicine or environmental pollution. The SN ratio recommended by Taguchi is based on the errors with the same loss coefficient to optimize the problems. However, the losses due to the errors are not equal in practice. This paper proposes a general model for optimizing parameter design and selecting threshold value for the digital dynamic systems where the output is classified into four classes. The implementation and the effectiveness of the proposed approach are illustrated through two case studies

Development of a 3D Parallel Mechanism Robot Arm with Three Vertical-Axial Pneumatic Actuators Combined with a Stereo Vision System

This study aimed to develop a novel 3D parallel mechanism robot driven by three vertical-axial pneumatic actuators with a stereo vision system for path tracking control. The mechanical system and the control system are the primary novel parts for developing a 3D parallel mechanism robot. In the mechanical system, a 3D parallel mechanism robot contains three serial chains, a fixed base, a movable platform and a pneumatic servo system. The parallel mechanism are designed and analyzed first for realizing a 3D motion in the X-Y-Z coordinate system of the robot’s end-effector. The inverse kinematics and the forward kinematics of the parallel mechanism robot are investigated by using the Denavit-Hartenberg notation (D-H notation) coordinate system. The pneumatic actuators in the three vertical motion axes are modeled. In the control system, the Fourier series-based adaptive sliding-mode controller with H∞ tracking performance is used to design the path tracking controllers of the three vertical servo pneumatic actuators for realizing 3D path tracking control of the end-effector. Three optical linear scales are used to measure the position of the three pneumatic actuators. The 3D position of the end-effector is then calculated from the measuring position of the three pneumatic actuators by means of the kinematics. However, the calculated 3D position of the end-effector cannot consider the manufacturing and assembly tolerance of the joints and the parallel mechanism so that errors between the actual position and the calculated 3D position of the end-effector exist. In order to improve this situation, sensor collaboration is developed in this paper. A stereo vision system is used to collaborate with the three position sensors of the pneumatic actuators. The stereo vision system combining two CCD serves to measure the actual 3D position of the end-effector and calibrate the error between the actual and the calculated 3D position of the end-effector. Furthermore, to verify the feasibility of the proposed parallel mechanism robot driven by three vertical pneumatic servo actuators, a full-scale test rig of the proposed parallel mechanism pneumatic robot is set up. Thus, simulations and experiments for different complex 3D motion profiles of the robot end-effector can be successfully achieved. The desired, the actual and the calculated 3D position of the end-effector can be compared in the complex 3D motion control

Aluminum with dispersed nanoparticles by laser additive manufacturing.

While laser-printed metals do not tend to match the mechanical properties and thermal stability of conventionally-processed metals, incorporating and dispersing nanoparticles in them should enhance their performance. However, this remains difficult to do during laser additive manufacturing. Here, we show that aluminum reinforced by nanoparticles can be deposited layer-by-layer via laser melting of nanocomposite powders, which enhance the laser absorption by almost one order of magnitude compared to pure aluminum powders. The laser printed nanocomposite delivers a yield strength of up to 1000 MPa, plasticity over 10%, and Young's modulus of approximately 200 GPa, offering one of the highest specific Young's modulus and specific yield strengths among structural metals, as well as an improved specific strength and thermal stability up to 400 °C compared to other aluminum-based materials. The improved performance is attributed to a high density of well-dispersed nanoparticles, strong interfacial bonding between nanoparticles and Al matrix, and ultrafine grain sizes

How do leaders react when treated unfairly? Leader narcissism and self-interested behavior in response to unfair treatment

In this article we employ a trait activation framework to examine how unfairness perceptions influence narcissistic leaders’ self-interested behavior, and the downstream implications of these effects for employees’ pro-social and voice behaviors. Specifically, we propose that narcissistic leaders are particularly likely to engage in self-interested behavior when they perceive that their organizations treat them unfairly, and that this self-interested behavior in turn decreases followers’ pro-social behavior and voice. Data from a multisource, time-lagged survey of 211 team leaders and 1,205 subordinates provided support for the hypothesized model. Implications for theory and practice are discussed

We have emotions but can’t show them! Authoritarian leadership, emotion suppression climate, and team performance

How do authoritarian leaders in modern organizations influence work team emotional climate and performance? Defining authoritarian leadership as an ambient, demanding, and controlling leadership style, we conducted a survey study of 252 leaders and 765 subordinates matched in 227 work teams in three large public Japanese organizations. The results indicate that authoritarian leaders are more likely to create a team climate of emotion suppression, which induces a higher level of team emotional exhaustion that negatively impacts team performance. Furthermore, we found that authoritarian leaders’ own emotion suppression enhances the above sequential mediation effects, i.e. the more emotion suppression the authoritarian leader him/herself exercises, the stronger the team climate of emotion suppression, the higher the level of team emotional exhaustion, and the lower the team performance. These findings suggest that leadership effectiveness may be improved if leaders can reduce their authoritarian behaviors and identify appropriate channels for employees to release emotions in the workplace