scholarly journals THERMOELECTRIC SEMICONDUCTOR DEVICES FOR THERMAL STABILISATION OF REA POWERFUL TRANSISTORS

2020 ◽  
Vol 47 (1) ◽  
pp. 30-38
Author(s):  
T. A. Ismailov ◽  
A. R. Shakhmaeva ◽  
A. M. Ibragimova
Keyword(s):  
Heat Dissipation ◽  
High Efficiency ◽  
Solid Phase ◽  
Electronic Devices ◽  
Experimental Studies ◽  
Thermoelectric Module ◽  
Optimal Designs ◽  
Excess Heat ◽  
Power Transistors ◽  
Low Energy Consumption

Abstract. Aim. The aim of the study is to analyse the problem of heat dissipation in high-power transistors and develop devices for their thermal stabilisation when used in electronic equipment. Method. A method is proposed for testing power transistors using a device to to ensure thermal stabilisation in the stating volume by means of a two-position temperature controller along with a model for the use of these components in electronic devices. The proposed devices support high thermal stabilisation accuracy of power transistors in a radioelectronic device system allowing temperature to be maintained at a given level with high accuracy by means of a thermoelectric battery. Results. Device designs were developed for increasing the accuracy of thermal stabilisation of power transistors with high efficiency, low energy consumption and small size. Conclusion. Based on the results of experimental studies, optimal designs for devices for the thermostabilisation of radioelectronic device components that dissipate significant power during their operation are presented. The devices can be used to increase the accuracy of thermal stabilisation of the radioelectronic device element by means of a working substance whose melting point coincides with its thermal stabilisation temperature. The developed devices have the following functions: the thermoelectric battery sections of the thermoelectric battery will be sequentially disconnected depending on the electrical signals from the temperature sensors to which the solid phase of the working substance has moved. The battery of the thermoelectric module (TEM) removes excess heat from the heat-stabilising substance while maintaining the required temperature of the radioelectronic device element. Excess heat from the heat-generating junctions of the TEM battery is removed by the heat exchanger. During melting of the working substance, the temperature of the thin-walled metal container – and, accordingly, the temperature of the CEA element – can be maintained at a constant value equal to the melting temperature of the working substance. 

A Study on the Control of Residual Stress of Copper Thick-Film Using 2D Nanomaterial

2021 ◽  
Vol 21 (12) ◽  
pp. 5960-5964
Author(s):  
Kwon Jai Lee ◽  
Jee Young Oh ◽  
Kyong Nam Kim
Keyword(s):  
Residual Stress ◽  
Heat Dissipation ◽  
High Efficiency ◽  
Rapid Development ◽  
Electronic Devices ◽  
Copper Film ◽  
Electronics Industry ◽  
Electronic Components ◽  
Graphene Layers ◽  
Electronic Parts

With the rapid development of the electronics industry, high-density electronic devices and component mounting have gained popularity. Because of the heat generated from these devices, efficiency of the electronic parts is significantly lowered and life of various electronic devices is considerably shortened. Therefore, it is essential to efficiently dissipate the heat generated from the device to extend product life and ensure high efficiency of electronic components. This study evaluated how residual stress is impacted by the thickness of the deposited copper film, which is widely used as a heat dissipation material, and the number of graphene layers. The results confirmed that the residual stress decreased with increasing thickness. Moreover, the residual stress changed based on the transfer area of graphene, which had an elastic modulus eight times that of copper, indicating that the residual stress of the deposited copper film can be controlled.

scholarly journals Individual prediction of the reliability of high power transistors for electronic devices of medical purposes

Doklady BGUIR ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. 88-95
Author(s):  
S. M. Borovikov ◽  
V. O. Kaziuchyts
Keyword(s):  
High Power ◽  
Electronic Devices ◽  
Operating Time ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Initial Moment ◽  
Technical Documentation ◽  
Power Transistors ◽  
Informative Parameters ◽  
Predictive Rule

When assembling electronic complexes for medical purposes, it is important to install highly reliable semiconductor devices in electronic equipment. Experimental studies and the example of high-power bipolar transistors in this work show how you can select copies of an increased level of reliability for their subsequent installation in critical electronic devices. To select highly reliable samples, individual forecasting was used according to informative parameters measured for a particular sample at the initial moment in time. Experimental studies (training experiment) included measuring at the initial moment of time for each sample of transistors of electrical parameters, which may contain information on reliability, and then conducting accelerated tests of transistors for reliability for a time corresponding to normal operating conditions specified in the technical documentation. The training experiment is performed once and used to obtain a predictive rule, which is applied to other similar samples that did not participate in the training experiment. To obtain a predictive rule, the method of majority logic was used. Prediction is performed in the form of assigning a specific sample to the class of highly reliable samples for a given future operating time. To perform prediction, the values of the informative parameters are measured at the initial moment of time for a particular sample of interest, they are converted into binary numbers (zero or one) using the threshold values found from the results of the training experiment, and the decision on the correspondence of the sample to the class of highly reliable transistors is made by a set of binary numbers. To classify a sample as a highly reliable one, it is sufficient that the number of ones exceeds the number of zeros in the resulting set of binary numbers.

A Study on the Use of Bipolar-Particles-Electrodes in Decolorization of Dyeing Effluents and Its Principle

1987 ◽  
Vol 19 (3-4) ◽  
pp. 391-400 ◽  
Author(s):  
Zhou Ding ◽  
Cai Wei Min ◽  
Wang Qun Hui
Keyword(s):  
Energy Consumption ◽  
High Efficiency ◽  
Low Energy ◽  
Acid Dyes ◽  
Underlying Principle ◽  
Low Energy Consumption ◽  
Transparent Liquid

This paper studies the use of bipolar-particles-electrodes in the decolorization of dyeing effluents. Treatment of highly colored solutions of various soluble dyes (such as direct, reactive, cationic or acid dyes) and also samples of dyeing effluents gave rise to an almost colorless transparent liquid, with removal of CODcr and BOD5 being as high as over 80%. The method is characterized by its high efficiency, low energy consumption and long performance life. A discussion of the underlying principle is given.

scholarly journals Experimental Investigation and Comparison of the Thermal Performance of Additively and Conventionally Manufactured Heat Exchangers

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 574
Author(s):  
Ana Vafadar ◽  
Ferdinando Guzzomi ◽  
Kevin Hayward
Keyword(s):  
Surface Roughness ◽  
Thermal Performance ◽  
Heat Exchangers ◽  
High Efficiency ◽  
Cooling System ◽  
Fluid Dynamic ◽  
Dynamic Performance ◽  
Experimental Studies ◽  
Manufacturing Method ◽  
Industrial Sectors

Air heat exchangers (HXs) are applicable in many industrial sectors because they offer a simple, reliable, and cost-effective cooling system. Additive manufacturing (AM) systems have significant potential in the construction of high-efficiency, lightweight HXs; however, HXs still mainly rely on conventional manufacturing (CM) systems such as milling, and brazing. This is due to the fact that little is known regarding the effects of AM on the performance of AM fabricated HXs. In this research, three air HXs comprising of a single fin fabricated from stainless steel 316 L using AM and CM methods—i.e., the HXs were fabricated by both direct metal printing and milling. To evaluate the fabricated HXs, microstructure images of the HXs were investigated, and the surface roughness of the samples was measured. Furthermore, an experimental test rig was designed and manufactured to conduct the experimental studies, and the thermal performance was investigated using four characteristics: heat transfer coefficient, Nusselt number, thermal fluid dynamic performance, and friction factor. The results showed that the manufacturing method has a considerable effect on the HX thermal performance. Furthermore, the surface roughness and distribution, and quantity of internal voids, which might be created during and after the printing process, affect the performance of HXs.

scholarly journals Experimental Evaluation of Airlift Performance for Vertical Pumping of Water in Underground Mines

2021 ◽  
Author(s):  
Parviz Enany ◽  
Oleksandr Shevchenko ◽  
Carsten Drebenstedt
Keyword(s):  
Water Flow ◽  
High Efficiency ◽  
Experimental Studies ◽  
Theoretical Models ◽  
Injection System ◽  
Experimental Investigations ◽  
Flow Mode ◽  
New Device ◽  
Riser Pipe ◽  
Airlift Pump

AbstractThis paper presents experimental studies on the optimization of air–water flow in an airlift pump. Airlift pumps use compressed gas to verticall transport liquids and slurries. Due to the lack of theoretical equations for designing and predicting flow regimes, experimental investigations must be carried out to find the best condition to operate an airlift pump at high efficiency. We used a new air injection system and different submergence ratios to evaluate the output of a simple pump for vertical displacement of water in an underground mine. The tests were carried out in a new device with 5.64 m height and 10.2 cm circular riser pipe. Three air-jacket pipes, at different gas flows in the range of 0.002–0.09 m3/s were investigated with eight submergence ratios. It was found that with the same air flow rate, the most efficient flow of water was achieved when an air jacket with 3 mm diameter holes was used with a submergence ratio between 0.6 and 0.75. In addition, a comparison of practical results with two theoretical models proposed by other investigators showed that neither was able to accurately predict airlift performance in air–water flow mode.

scholarly journals Antireflective and Superhydrophilic Structure on Graphite Written by Femtosecond Laser

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 236
Author(s):  
Rui Lou ◽  
Guangying Li ◽  
Xu Wang ◽  
Wenfu Zhang ◽  
Yishan Wang ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Near Infrared ◽  
High Efficiency ◽  
Electronic Devices ◽  
Sample Surface ◽  
Graphite Surface ◽  
Hazardous Substances ◽  
Functional Surface ◽  
Nano Structures ◽  
Average Reflectance

Antireflection and superhydrophilicity performance are desirable for improving the properties of electronic devices. Here, we experimentally provide a strategy of femtosecond laser preparation to create micro-nanostructures on the graphite surface in an air environment. The modified graphite surface is covered with abundant micro-nano structures, and its average reflectance is measured to be 2.7% in the ultraviolet, visible and near-infrared regions (250 to 2250 nm). The wettability transformation of the surface from hydrophilicity to superhydrophilicity is realized. Besides, graphene oxide (GO) and graphene are proved to be formed on the sample surface. This micro-nanostructuring method, which demonstrates features of high efficiency, high controllability, and hazardous substances zero discharge, exhibits the application for functional surface.

Preparation of Poly(Lactic Acid) Acrylate for UV-Curable Coating Applications

2015 ◽  
Vol 659 ◽  
pp. 570-574 ◽  
Author(s):  
Apinya Musidang ◽  
Nantana Jiratumnukul
Keyword(s):  
Lactic Acid ◽  
Physical Properties ◽  
High Efficiency ◽  
Low Energy ◽  
Poly Lactic Acid ◽  
Coating Film ◽  
Pencil Hardness ◽  
Uv Curable ◽  
Low Energy Consumption ◽  
Volatile Organic

UV-curable process is widely used for paints, inks and adhesives due to its rapid curing, low energy consumption, high efficiency and low volatile organic compounds (VOCs). The objective of this research is to prepare poly(lactic acid) (PLA) based UV-curable coating by using glycolyzed PLA. PLA was glycolyzed by ethylene glycol (EG) at 170°C for 90 minutes. The obtained glycolyzed PLA was reacted with methacrylic anhydride (MAAH) to provide PLA acrylate oligomer. The obtained PLA acrylate oligomer was used in coating formulations with various amounts of photoinitiator and cured under UV radiation. Physical properties of cured coating film were investigated such as pencil hardness, gloss and haze. The results showed that poly(lactic acid) (PLA) based UV-curable coating provided good physical properties.

High-Efficiency On-Line Solid-Phase Extraction Coupling to 15−150-μm-i.d. Column Liquid Chromatography for Proteomic Analysis

2003 ◽  
Vol 75 (14) ◽  
pp. 3596-3605 ◽  
Author(s):  
Yufeng Shen ◽  
Ronald J. Moore ◽  
Rui Zhao ◽  
Josip Blonder ◽  
Deanna L. Auberry ◽  
...  
Keyword(s):  
Column Liquid Chromatography ◽  
Liquid Chromatography ◽  
Solid Phase Extraction ◽  
Proteomic Analysis ◽  
High Efficiency ◽  
Solid Phase ◽  
Phase Extraction ◽  
On Line
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