Thermoelectric-based cooling system for high-speed motorized spindle I: Design and control mechanism

With the increase of spindle speed, heat generation becomes the crucial problem of high-speed motorized spindle. A new cooling system for motorized spindle is proposed based on the principles of thermoelectric refrigeration and fast heat conduction. The main strategy of the proposed ThermoElectric-based Cooling System (TECS) is using the ThermoElectric Cooler (TEC) to cool the spindle through a Heat Conduction Sleeve (HCS). The TEC is designed according to the heat generation of motorized spindle. The cooling capacity generated by the TEC is controlled by electric current passing through the TEC according to the temperature rise of HCS. The HCS is designed to distribute the cold quickly and is installed around the spindle sleeve working as cooling medium. The simulation results show that the cooling effect of the proposed TECS is better than water water-cooling system. It is meaningful to improve the accuracy of motorized spindle.

Efficient Use of Carbon Fibers as Heating Elements for Curing of Epoxy Matrix Composites

The aim of this study is to achieve a fully cured thermoset matrix that is heated by a direct electric current passing through the reinforcement fibers i.e., the Joule heating effect. Two types of fibers were used as heating elements for curing the epoxy resins. Kanthal resistance fibers were used as reference heating elements and subsequently, they were replaced by a Torayca Carbon Tow of the same radius. The specimens were cured by the heat produced by a direct electric current passing through the fibers and achieving temperatures of 50 °C and 70 °C. Specimens cured in a conventional oven were also manufactured, to compare the resistance heating method to the conventional one. Next, all specimens were mechanically characterized in a quasi-static three-point bending mode of loading and experimental results were compared to derive useful conclusions concerning the applicability of the technique to polymer/composite materials mass production. Finally, a preliminary economical study concerning power consumption needed for the application of both the traditional oven curing and the carbon fibers heating elements use for the manufacturing of the same amounts of materials is presented, showing a maximum financial benefit that can be achieved, on the order of 68%.

Influence of environmental conditions on the earth pit resistance using earth pit simulator

Introduction: Electrocution is the cause of many deaths in the world annually, that electric current passing between the body and earth can be the reason; thus, it is of great importance to construct the ground protection system using earth pit. This study aimed to investigate the effective environmental conditions on the earth's pit resistance using the simulation method. Materials and Methods: In the present study, 192 different experiments were performed and repeated ten times. The parameters evaluated in this study include soil type, reducing agents type, depth, humidity, electrode type, soil density, and electrode placement shape. The resistance value is measured using a three-point ether tester by changing each of them. The obtained data were statistically analyzed, and the results were presented in tables. Results: According to the results of the experiments, soil density and moisture are considered the most effective parameters in determining the resistance of the earth pit; so that the value of resistance is significantly reduced by changing these two parameters separately or simultaneously. Also, as density and depth of placement increase, the value of resistance in all experiments had a decreasing trend. This study showed that sand was determined as the worst soil type among the soil types due to its high resistance. Conclusion: According to the results of this study, soil density and moisture among the seven parameters under study play a more important role in pit resistance and consequently the severity of an electric shock that should be given more attention to it.

Electrical Characteristics of Underwater Human Body Model in Charging Power Facility

In this study, the electrical simulation of electric shock accidents at a voltage of 220 V was investigated using Andrew s body model in water. The constructed circuit consisted of Andrew s body model. The voltages measured on a hand, breast, waist, were compared with the electric currents measured on the hand, breast, and waist considering the safety limit of an electric current passing through the body. From the results, it can be understood that the magnitude and wave of electric current passing through the body affect the heart s control of a signal, which directly affects the ventricle of the heart in detail. It comes from the simulation through the ATP -Draw program. This study could be useful in solving safety issues for the electric angle limit by measuring flooding body resistance, as well as the voltage and current passing through each part.

A study on reinforcement corrosion of concrete structures near coastal areas of Oman

A lot of buildings and structures in coastline areas facing many issues such as huge number of cracks shown on the wall structures. Moreover, this issue is affecting the aesthetic and the beauty of the buildings. Research discover that reasons behind this problem is concrete corrosion or especially corrosion of steel that causes enormous damage to the structure. This issue starts when the chloride is containing in concrete and due to formation of the oxide film. Rapid chloride permeability test according to ASTM C1202 is performed to study the behavior of different concrete mixes such as normal concrete, concrete with fly ash and concrete with Ground Granulated Blast-furnace slag(GGBFS). In this experiment when the concrete blocks are dipped into the solution, the electric current passes through it in order to determine the permeability of the material. In addition, corrosion acceleration test is performed to observe the electric current flow through the different mixes with different time intervals and days when it is merged to sodium chloride (NaCl). From the rapped chloride permeability test results, it is found that the permeability of chloride of all mixes is categorized as a moderate. From the corrosion acceleration test, it is found that all specimen of concrete containing fly ash had an attack at the first days of the test. A little rust appears on the normal concrete mix in the second week as the magnitude of electric current passing through it was not stable.

Design and development of a wedge shaped magnetorheological clutch

This paper presents a novel drum magnetorheological clutch design having a wedge shaped boundary. The converging film formed due to the direction of motion of the magnetorheological clutch and the inclination of the wedge planes helps to produce the pressure generating mechanism in the magnetorheological grease film. The resistance force developed due to this mechanism in the proposed case exceeds that of the conventional drum clutch. The proposed wedge shaped drum magnetorheological clutch consists of bimetallic discs made up of aluminium and mild steel. Mild steel disc has a certain number of inclined sliders shaped like a wedge at its boundary, which is immersed in the magnetorheological grease. The yield stress of the magnetorheological grease varies as a function of the magnetic field created by electric current passing through the electromagnet. Bingham model has been employed in the present study to analyse theoretically the torque generated by wedge-shaped drum magnetorheological clutch. The proposed magnetorheological drum clutch with wedge shaped boundary and conventional drum clutch have been designed and fabricated with similar material parameters and magnetic circuits. The experiment has been performed for the different current values (0 A, 0.25 A and 0.52 A). Torque results are plotted and compared for both cases. Experimental results suggest that the proposed wedge shaped drum magnetorheological clutch produces more torque than the conventional drum magnetorheological clutch, and thus it has better performance.

Development of electrically conductive concrete

The effects of the addition of steel fiber and graphite powder on the electric conductivity of concrete were investigated. The percolation transition zone of the concrete + steel fiber was determined, thus fixing the optimum content of steel fiber at 8.5%. Graphite was added to investigate its influence on the electrical conductivity and mechanical properties of the concrete. The electric current passing through the specimens was measured, setting the electric voltage to 50 V. The surface temperature of the specimens submitted to the electrical current was measured for 20 min. It was observed that the higher the graphite addition, the higher the conductivity was and, therefore, the higher the final temperature, which achieved 58 °C higher than the reference mixture, but the compressive strength decreased from 60 to 30 MPa, although still considered as structural concrete.

Incorporation of Reversible Electroporation Into Electrolysis Accelerates Apoptosis for Rat Liver Tissue

Tissue electrolysis is an alternative modality that uses a low intensity direct electric current passing through at least 2 electrodes within the tissue and resulting electrochemical products including chlorine and hydrogen. These products induce changes in pH around electrodes and cause dehydration resulting from electroosmotic pressure, leading to changes in microenvironment and thus metabolism of the tissues, yielding apoptosis. The procedure requires adequate time for electrochemical reactions to yield products sufficient to induce apoptosis of the tissues. Incorporation of electroporation into electrolysis can decrease the treatment time and enhance the efficiency of electrolytic ablation. Electroporation causes permeabilization in the cell membrane allowing the efflux of potassium ions and extension of the electrochemical area, facilitating the electrolysis process. However, little is known about the combined effects on apoptosis in liver ablation. In this study, we performed an immunohistochemical evaluation of apoptosis for the incorporation of electroporation into electrolysis in liver tissues. To do so, the study was performed with microelectrodes for fixed treatment time while the applied voltage varied to increase the applied total energy for electrolysis. The apoptotic rate for electrolytic ablation increased with enhanced applied energy. The apoptotic rate was 4.31 ± 1.73 times that of control in the synergistic combination compared to 1.49 ± 0.33 times that of the control in electrolytic ablation alone. Additionally, tissue structure was better preserved in synergistic combination ablation compared to electrolysis with an increment of 3.8 mA. Thus, synergistic ablation may accelerate apoptosis and be a promising modality for the treatment of liver tumors.

Enhancing CO2 methanation over a metal foam structured catalyst by electric internal heating

We develop an electric internal heating method based on a Ni-foam structured catalyst for CO2 methanation, in which the Joule heat generated by electric current passing through the catalyst drives the reaction.