Silica particles settling characteristics and removal performances of oxide chemical mechanical polishing wastewater treated by electrocoagulation technology

The purpose of this study was to explore the feasibility of removing silica particles and reducing turbidity from oxide chemical mechanical polishing (oxide-CMP) wastewater. Based on the dynamic characteristics of batch electrocoagulation, three operating stages (lag, reactive, and stabilizing) are proposed to identify the relationships among the zeta potential of the silica particles, solution turbidity, and the corresponding mean particle size of the silica. Experimental results show that the silica particles were destabilized and settled at the critical mean particle size, which was estimated to be above 520 nm after 10 min, and the corresponding turbidity removal mostly occurred during the reactive stage. Furthermore, the corresponding mean particle size varied from 520 to 1900 nm as the treatment time progressed from 10 to 20 min, which also occurred during the reactive stage. Several parameters, including different electrode pairs, electrolyte concentration, applied voltage, and the optimum condition of power input were investigated. Experimental results indicate that a Fe/Al electrode pair is the most efficient choice of the four electrode pair combinations in terms of energy consumption. The optimum electrolyte concentration and applied voltage were found to be 200 ppm NaCl and 30 V, respectively.     

Silica particles settling characteristics and removal performances of oxide chemical mechanical polishing wastewater treated by electrocoagulation technology

This study aimed at investigating the feasibility of using jackfruit peel (JFP), a solid waste, abundantly available in Malaysia, for the adsorption of methylene blue, a cationic dye. Batch adsorption studies were conducted to evaluate the effects of contact time, initial concentration (35-400mg/L), pH (2-11), and adsorbent dose (0.05-1.20g) on the removal of dye at temperature of 30 degrees C. The experimental data were analyzed by the four different types of linearized Langmuir isotherm, the Freundlich isotherm and the Temkin isotherm. The experimental data fitted well with the type 2 Langmuir model with a maximum adsorption capacity of 285.713mg/g. Pseudo-first and pseudo-second-order kinetics models were tested with the experimental data, and pseudo-second-order kinetics was the best for the adsorption of MB by JFP with coefficients of correlation R(2)> or =0.9967 for all initial MB concentrations studied. The results demonstrated that the JFP is very effective for the adsorption of methylene blue (MB) from aqueous solutions.     

Using throughput profit for selecting manufacturing process plan

In a task of process plan selection using workstations, manufacturing process plans have different precedence relationships, unequal operating times, and so on. It is necessary to consider these factors in evaluation models. Due to the use of different machines and tools that would increase the line efficiency with additional cost, a traditional total cost is not a good measure for the selection of manufacturing process plans. Hence, an evaluation model using throughput profit for each manufacturing process plan is proposed. In the first step of the proposed method, the precedence relationships of the manufacturing process for each part are decomposed. Several feasible combinations with different numbers of workstations and different task assignments are generated using a line balancing method. Then, an optimization model with associated throughput profit for process parameters is used for choosing the manufacturing process plans. Implementation examples are presented to illustrate this proposed procedure.     

A Vision-Based Augmented-Reality System For Multiuser Collaborative Environments

This work presented a novel vision-based augmented-reality system for applications in multiuser collaborative environments. The kernel technology of this vision-based system locates the cameras that are utilized to point and simulate the positions of multiple viewers. Camera calibration based on computer vision is employed during the camera's locating process. The applications in multiuser collaborative environments allow the viewers to view various positions and in numerous directions. However, traditional calibration approaches are not suitable for these cases sufficiently. A novel calibration pattern based on pseudo-random arrays is designed for multiuser collaborative applications. The pattern has a simple and regular structure, easily extracts features, achieves robust recognition using local information, and does not limit viewer positions and directions. Experimental results indicate that the proposed system provides a effective platform for applications in multiuser collaborative environments.     

Fatigue Deformation Mechanisms of Zirconia Ceramics

Two distinct fatigue deformation mechanisms, microcracking and transformation plasticity, have been identified in 3Y-TZP and Mg-PSZ. Microcracking is dominant in 3Y-TZP, while transformation plasticity is more evident in Mg-PSZ. However, the proportion of these two mechanisms is dependent on the frequency and stress amplitude, with transformation plasticity favored at low frequency and high stress. Generally, microcracks form in the tensile half-cycle and partly close in the compressive half-cycle, whereas transformation from the tetragonal to the monoclinic phase, as well as the reverse transformation, can occur in both tension and compression. Under stress-controlled cycling, although the initial hysteresis loop is highly asymmetric with respect to the stress, cyclic softening and the development of an internal stress cause it to gradually evolve to yield an essentially symmetric cyclic stress–strain curve.