Examination into Para Rubber Trade between Thailand and China Business Development’s Implications

This article examines the circumstance surrounding the Para rubber commerce between Thailand and China. The focus is on the factors that have had the impacts on the Para rubber commerce between Thailand and China.  The study shows the obstacles of China’s Para rubber imports and the higher quantity of China’s Para rubber, the unstable of the Para rubber’s prices, the causes of Thailand slowly Para rubber production and the interrupted flows of the news on Para rubber between Thailand and China.  The proposal on how to tackle the hurdles from China’s Para rubber import, to promote the cooperatives in Para rubber commerce between Thailand and China is developed. This development recognizes the roles of relevant public agencies on both sides to help business development. Keywords: Para rubber, business development, and international trad

Representation and Outcome of Catheter Ablation for Treatment of Atrial Fibrillation Among Patients with Obesity: A Systematic Review of Randomized Control Studies

https://digitalcommons.unmc.edu/surp2022/1018/thumbnail.jp

Whole -body human -to -humanoid motion transfer with balance manipulability ellipsoid

This thesis aims at generating human-like, whole-body humanoid motion trajectories and introducing a new measure for measuring the ability of a humanoid robot to maintain its balance. The thesis addresses two important issues in the whole-body humanoid trajectory generation. First, we propose the whole-body trajectory generation based on motions captured from a human with trajectory adjustment based on double-layer-prioritized constraints. Several motion-capturing experiments were performed on a human to capture essential body movements, which were used to generate humanoid movements. The aim is to produce whole-body human-like humanoid movements that are compliant with different human-humanoid constraints, which are related to the problem of model and task discrepancies between humans and humanoid robots. Constraint prioritization is applied to eliminate any disagreement among conflicting constraints. Computer simulations based on a HOAP-2 humanoid-robot model were conducted to illustrate the performance and consistency of the proposed whole-body humanoid trajectory generation from the captured human motions. Second, we investigate the ability of a humanoid robot to maintain its balance by proposing the Zero Moment Point (ZMP) manipulability ellipsoid as a graphical representation of the ability of a humanoid robot to manipulate its ZMP. The size and shape of the ZMP manipulability ellipsoid are functions of the actuator limits and the current posture of a humanoid robot. The ZMP manipulability ellipsoid represents an area in which a humanoid robot can instantly move its ZMP based on the available actuating limits and posture to any location inside the area covered by the ellipsoid. We found that the existence of the overlapping area of the ellipsoid and the base of the support area can be used to predict whether the humanoid has an adequate actuating torque to maintain balance through the postural balance control. If the postural balance control is not possible to maintain its balance due to the lack of actuating torque, then it would be necessary to initiate a step to maintain its stability. The ability to predict the necessity of stepping based on actuator limits is the strength of the proposed ZMP manipulability ellipsoid

Real-Time Temperature Measurement Using Infrared Thermography Camera and Effects on Tensile Strength and Microhardness of Hot Wire Plasma Arc Welding

The hot wire plasma arc welding process, a hybrid process between the plasma arc welding (PAW) process and hot wire process, is used to weld 316 stainless steel sheets, in which the temperature generated during welding is recorded in real time with a high-speed infrared thermography camera. Therefore, this research studies the factors in the hot wire process, of which there are two: (1) wire feed rate and (2) wire current; this study investigated the tensile strength, microhardness, and relationship of cooling rate per tensile strength and microhardness. The study found that the hot wire current plays an important role in cooling rates and tensile strength. The temperature results from high-speed infrared thermography camera show that the maximum welding temperature is around 1300 °C. The weld pool has a temperature between 900 and 1300 °C and the temperature profile of the weld pool will look like an “M” shaped, which is caused by the hot wire process. Finally, the appropriate hot wire parameters are 1.5 m/min for wire feed rate and 40A for wire current, which will give the workpiece cooling rate of 800–500 °C as 13.42 °C/s, tensile strength of 610.95 MPa, and the average Vickers microhardness of 195 HV

Finite element analysis of the effect of porosity on residual stress in 2024 aluminium alloy GTAW

Simulations of the welding process for butt joints using finite element analysis (FEA) of the effect of porosity are presented. The metal used was aluminium alloy (grade 2024), and the filler material was alloy ER5356. The simulations were performed using the commercial software ANSYS, considering a double ellipsoid heat source, temperature-dependent material properties, material deposits, mechanical analysis, transient heat transfer, and defects (porosity). In this study, the FEA simulations were constructed for two types of heat source (single- and double-ellipsoid) used in gas tungsten arc welding (GTAW), and the calculated residual stress results were compared with the experimental values. Two double ellipsoid models were constructed for cases with and without porosity. The porosity was measured by three-dimensional (3D) computed tomography (CT), and the size and location of pores were mapped onto the weld bead created by the birth-and-death technique

Experimental Investigation of Additive Manufacturing Using a Hot-Wire Plasma Welding Process on Titanium Parts

In this paper, we propose hot-wire plasma welding, a combination of the plasma welding (PAW) process and the hot-wire process in the additive manufacturing (AM) process. Generally, in plasma welding for AM processes, the deposit grain size increases, and the hardness decreases as the wall height increases. The coarse microstructure, along with the large grain size, corresponds to an increase in deposit temperature, which leads to poorer mechanical properties. At the same time, the hot-wire laser process seems to contain an overly high interstitial amount of oxygen and nitrogen. With an increasing emphasis on sustainability, the hot-wire plasma welding process offers significant advantages: deeper and narrow penetration than the cold-wire plasma welding, improved design flexibility, large deposition rates, and low dilution percentages. Thus, the hot-wire plasma welding process was investigated in this work. The wire used in the welding process was a titanium American Welding Society (AMS) 4951F (Grade 2) welding wire (diameter 1.6 mm), in which the welding was recorded in real time with a charge-coupled device camera (CCD camera). We studied three parameters of the hot-wire plasma welding process: (1) the welding speed, (2) wire current, and (3) wire feeding speed. The mechanical and physical properties (porosity, Vickers hardness, microstructure, and tensile strength) were examined. It was found that the number of layers, the length and width of the molten pool, and the width of the deposited bead increased, while the height of the layer increased, and the hot-wire current played an important role in the deposition. In addition, these results were benchmarked against specimens created by a hot-wire plasma welding/wire-based additive manufacturing process with an intention to develop the hot-wire PAW process as a potential alternative in the additive manufacturing industry

Experimental Investigation of Additive Manufacturing Using a Hot-Wire Plasma Welding Process on Titanium Parts

In this paper, we propose hot-wire plasma welding, a combination of the plasma welding (PAW) process and the hot-wire process in the additive manufacturing (AM) process. Generally, in plasma welding for AM processes, the deposit grain size increases, and the hardness decreases as the wall height increases. The coarse microstructure, along with the large grain size, corresponds to an increase in deposit temperature, which leads to poorer mechanical properties. At the same time, the hot-wire laser process seems to contain an overly high interstitial amount of oxygen and nitrogen. With an increasing emphasis on sustainability, the hot-wire plasma welding process offers significant advantages: deeper and narrow penetration than the cold-wire plasma welding, improved design flexibility, large deposition rates, and low dilution percentages. Thus, the hot-wire plasma welding process was investigated in this work. The wire used in the welding process was a titanium American Welding Society (AMS) 4951F (Grade 2) welding wire (diameter 1.6 mm), in which the welding was recorded in real time with a charge-coupled device camera (CCD camera). We studied three parameters of the hot-wire plasma welding process: (1) the welding speed, (2) wire current, and (3) wire feeding speed. The mechanical and physical properties (porosity, Vickers hardness, microstructure, and tensile strength) were examined. It was found that the number of layers, the length and width of the molten pool, and the width of the deposited bead increased, while the height of the layer increased, and the hot-wire current played an important role in the deposition. In addition, these results were benchmarked against specimens created by a hot-wire plasma welding/wire-based additive manufacturing process with an intention to develop the hot-wire PAW process as a potential alternative in the additive manufacturing industry