scholarly journals Investigation on failure mechanism of electrical connectors under repetitive mechanical insertion and withdrawal operations

2021 ◽  
Vol 1207 (1) ◽  
pp. 012011
Author(s):  
Yuan Meng ◽  
Wanbin Ren
Keyword(s):  
Contact Resistance ◽  
Extraction Process ◽  
Degradation Behavior ◽  
Oxidative Wear ◽  
Physical Mechanisms ◽  
Electrical Connector ◽  
Initial Stage ◽  
Alloy Material ◽  
Fluctuation Phenomenon ◽  
Increasing Trend

Abstract Electrical connector is an essential accessory component for electrical and electronic interconnection circuit. In order to investigate the degradation behavior of electrical connector, a series of repetitive mechanical insertion and withdrawal operations of electrical connector have been carried out. The results indicate that there is an increasing trend in insertion/extraction force in the initial stage. Afterwards, it becomes a gradually decreasing trend attributed to the mechanical wear of the contact components. In addition, the oxidative wear of substrate copper alloy material causes the fluctuation phenomenon of contact resistance. The relevant mathematic models for insertion/extraction force and contact resistance calculation are presented to research the dynamic insertion/extraction process. Finally, the degradation behavior and associated physical mechanisms are proposed by analysing the laser confocal photographs and parameter waveforms comparison.

scholarly journals Kinetics of Extraction of Dioscine from Vegetable Raw Materials in Vibrocavitation Homogenizer

2020 ◽  
Vol 9 (2) ◽  
pp. 77-81 ◽  
Author(s):  
E. V. Flisyuk ◽  
S. S. Belokurov ◽  
I. A. Narkevich ◽  
A. N. Shikov ◽  
O. M. Flisyuk ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Plant Material ◽  
Raw Materials ◽  
Extraction Process ◽  
Rotor Speed ◽  
Plant Materials ◽  
Periodic Action ◽  
Initial Stage ◽  
Working Volume ◽  
Kinetics Of

Introduction. In recent years, substances extracted from plant materials have been widely used in the pharmaceutical, cosmetic and food industries. Such substances are used as solutions, dry extracts for the manufacture of medicines, dietary supplements, cosmetic creams, food additives in various forms – tablets, capsules, solutions, granular powders. The extraction of valuable substances from plant materials is carried out using the extraction process, which is carried out by various methods and in apparatuses of various designs. Earlier, a comparative study of the extraction of dioscin from fenugreek by various methods was carried out: in devices with a stirrer, in an ultrasonic field, supercritical, fluid CO2 extraction, and in a vibro-cavitation homogenizer. It is shown that the most effective method is the extraction carried out in a vibrocavitation homogenizer.Aim.To analyze the kinetics of the extraction of dioscin from fenugreek seeds, to determine the optimal values of the required degree of grinding of the raw materials, working temperature, the concentration of ethyl alcohol in the solution and the rotational speed of the rotor of the vibrocavitation homogenizer. Determine the effective mass transfer coefficient responsible for the intensity of mass transfer inside the particles.Materials and methods. An experimental study of the extraction of valuable components from plant materials was carried out in a laboratory unit with a vibrocavitation homogenizer of periodic action. As raw materials were used seeds of hay fenugreek, ecotype of Morocco, acquired in the company Fitokasa, Casablanca (Morocco), which we used for research. Commodity analysis showed that raw materials comply with the requirements of the State Pharmacopoeia XIVth edition. As extractants, aqueous solutions of ethanol with an alcohol concentration of 40, 50, 60, 70, 80, and 90 %. The analysis of the kinetics of the process was based on the following ideas. Extraction begins with the surface of the particles of plant material. As the extracted component moves into the volume of the solution, the extractant penetrates into the internal pores of the particles, and the surface on which the extractant and the extracted component interact is gradually shifted into the individual particles. In this case, the resistance to mass transfer in the region between the specified surface and the outer surface of the particle increases over time.Results and discussion. An analysis of the results shows that the rotor speed significantly intensifies the process. In addition, the influence of the rotor speed is most pronounced at the initial stage of the process, when the surface layers of particles of plant material are extracted. It was also found that the resistance to mass transfer inside particles increases significantly as it approaches the final stage of the process, and with an increase in the rotor speed, it increases, especially at the initial stage of the process, which is associated with the intensity of cavitation and the weakening of its effect as the process deepens inward particles.Conclusions. The obtained dependences are necessary to determine the duration of the extraction process in a batch mode, or the average residence time of seeds in the working volume when organizing the process in a continuous mode.

scholarly journals Problems of seasonality of sugar production from beets

2020 ◽  
Vol 82 (1) ◽  
pp. 64-69 ◽  
Author(s):  
V. A. Golybin ◽  
V. A. Fedoruk ◽  
N. A. Matvienko
Keyword(s):  
Diffusion Process ◽  
Raw Materials ◽  
Sugar Content ◽  
Extraction Process ◽  
Feed Water ◽  
Negative Consequences ◽  
Root Crops ◽  
Initial Stage ◽  
Beet Pulp ◽  
Physical And Chemical

In recent years, the annual processing of sugar beet in Russia is 45 million tons or more, which allows to produce white sugar in the amount of 6.0 million tons or more. during the production season, the quality of beets does not remain constant – not only its sugar content changes, but also the content of harmful soluble non-sugars, as well as physical and chemical parameters - the mass of root crops decreases due to wilting, reducing turgor, respiration and germination, rotten mass appears as a result of microbiological and enzymatic processes and the formation of foci of mucous bacteriosis. One of the main tasks of improving the diffusion process is to increase the elasticity of beet tissue and reduce the intensity of the transition of pectin substances into the diffusion juice. This goal is achieved by using effective chemical reagents in the composition of the feed water introduced into the diffusion apparatus, as well as processing of beet chips immediately before the sucrose extraction process; reducing the temperature of desugarisation of beet pulp in the diffusion apparatus in the allowable interval. The method of intensification of sucrose extraction using the method of treatment of feed water in an electric field is proposed. Improvement of the dispersed composition of the resulting sediment particles is facilitated by the return to the preliming of the carbonate suspension of juice II saturation, carried out using an activated suspension of filter perlite. The homogeneity of calcium carbonate particles and correspondingly high filtration rates of saturation juice are formed due to the active circuit of the internal circulation of the juice. The use of the proposed recommendations during the implementation of technological processes in their implementation in modern equipment of the diffusion process and purification of the obtained juice allow to minimize the negative consequences of beet processing both at the initial stage of the production season when technically not ripe root crops are received, and during the end of the season when processing raw materials of reduced quality.

The Physical and Chemical Properties Changes of Broth during Phellinus fermentation

2013 ◽  
Vol 295-298 ◽  
pp. 279-282
Author(s):  
Zi Ping Zhu ◽  
Jian Zhong Chen ◽  
Bei Bei Lv ◽  
Xue Ming Tang
Keyword(s):  
Fermentation Process ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Soluble Protein Content ◽  
Physical Chemical ◽  
Initial Stage ◽  
Increasing Trend ◽  
Physical And Chemical ◽  
And Chemical Properties ◽  
Variation Tendency

The physical and chemical properties changes of broth in the fermentation process of Phellinus and its mutant strain were studied. The results showed that the mycelia yield of the two strains of Phellinus increased rapidly in the first 6 days and increased slowly 6 days later, the soluble protein content of broth took on an increasing trend, up to 0.15 mg/mL and 0.13 mg/mL respectively, the variation tendency of the content of polysaccharide and viscosities of broth were semblable, that was declined in the initial stage of fermentation and change little in later stage. The physical, chemical properties and viscosities show similarity in both two strains’ broth, therefore, the physical and chemical properties of broth in the fermentation process of Phellinus changed regularly.

scholarly journals Evolution of contact performance of industry electrical connector based on reliability accelerated testing

2021 ◽  
Vol 13 (2) ◽  
pp. 168781402199882
Author(s):  
Jing Ni ◽  
Lidong Han ◽  
Jianfeng Pan ◽  
Junqiang Zheng ◽  
Yu Shi ◽  
...  
Keyword(s):  
Contact Resistance ◽  
High Speed ◽  
Friction And Wear ◽  
Adhesive Wear ◽  
Accelerated Testing ◽  
Mating Speed ◽  
Electrical Connector ◽  
External Conditions ◽  
Probability Of Fracture ◽  
Electrical Connectors

The evolution of contact performance of electrical connectors, as an expression of service performance, played a significant role in various electronic equipment or system. However, very few methods had been used to detect the evolution of contact performance effectively and accurately. Hence, in this research, reliability accelerated testing was conducted to investigate the evolution of contact performance of electrical connectors. To detect the evolution of contact performance, contact resistance and friction and wear of the connector were measured using a DC resistance tester and an electron microscope respectively. Also, the effect of external conditions such as ambient temperature, mating speed, mating cycles was statistically investigated, and evolution curves were developed for contact resistance and abrasion loss. The obtained results revealed the temperature and mating speed affected the contact performance of electrical connectors. The increment of temperature reduced the shear strength of material and increased the thickness of oxide film. Increased mating speed greatly increased the probability of fracture of micro-protrusion due to collision, the wear form of connector had realized transition from low-speed adhesive wear to high-speed peeling wear. In addition, when the connector was mated about 3000 cycles, the contact performance of the connector would be greatly decreased.

A Model to Predict Contact Resistance During Contact Solidification in Ribbon Growth on Substrate Process

2011 ◽  
Author(s):  
James McFall ◽  
Ronghui Ma
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Contact Resistance ◽  
Unit Cell ◽  
Transfer Model ◽  
Molten Silicon ◽  
Interfacial Heat Transfer ◽  
Transfer Resistance ◽  
Initial Stage ◽  
Ribbon Growth

Ribbon Growth on Substrate (RGS) has emerged as a promising method for growing multicrystalline silicon wafer directly on a substrate for photovoltaic applications. In this method, the wafer forms as a substrate contacts molten silicon for a controlled period of time. Due to the surface roughness, a thin layer of air is trapped at the interface of the substrate and molten silicon, leading to a contact resistance to heat transfer. The interfacial heat transfer plays an important role in determining the subcooling rate and nucleation, which defines the structural characteristics of the wafer. The contact resistance has been identified as an important phenomenon that affects solidification at the interface. It is dependent on many factors such as the roughness and wetting of the substrate as well as the substrate pre-heating temperature. Quantitative knowledge of the interfacial heat transfer resistance is essential for control of the solidification process. A mathematical model is presented for quantification of the interfacial heat transfer resistance during the initial stage of the solidification for RGS process. A three dimensional unit cell is constructed to represent the contact geometry and interface characteristics. The surface roughness, the mean trapped air layer between the substrate and the liquid, the parameters of area density and the radius of contact spots will be included in the geometry of the unit cell. A microscale heat transfer model is developed to describe conduction and radiation across the interface to quantify the contact heat transfer resistance as a function of surface roughness, morphology and preheating temperatures of the substrate. The contact resistance is incorporated into a heat transfer model and predicts the temperature variation with time in the substrate during the initial stage of contact. The presented model provides a valuable tool to predict the effect of various process parameters and substrate surface roughness on wafer growth during the RGS process.

Improving GaAs Chip yield And Enhancing Reliability of GaAs Devices

2001 ◽  
Vol 699 ◽  
Author(s):  
Kanti Prasad
Keyword(s):  
Integrated Circuits ◽  
Contact Resistance ◽  
Driving Force ◽  
Analytical Techniques ◽  
Microwave Integrated Circuits ◽  
Monolithic Microwave Integrated Circuits ◽  
Physical Mechanisms ◽  
Gaas Devices ◽  
Permissible Range

AbstractThe purpose of this research is to improve GaAs yield and enhance the reliability of GaAs MMICs (Monolithic Microwave Integrated Circuits) by first understanding the physical mechanisms of GaAs, Ni,Au-Ge eutectic and Au alloying process. Ohmic ooze has been driving force for this research. Variety of innovative experiments has been designed, so that contact resistance may be guaranteed to be within the permissible range. This resulted into the development of analytical techniques to measure contact resistance to GaAs as a result of alloying process employing Ni,Au-Ge and Au.

Study on Electrical Contact Degradation Behavior of Beryllium Bronze

2013 ◽  
Vol 341-342 ◽  
pp. 109-113
Author(s):  
Ai Ai Zhang ◽  
Wei Fang Zhang ◽  
Yu Long Zhang ◽  
Shi Jun Zhao
Keyword(s):  
Contact Resistance ◽  
Normal Stress ◽  
Electrical Contact ◽  
Degradation Behavior ◽  
Arrhenius Model ◽  
Accelerated Degradation ◽  
Beryllium Bronze ◽  
Degradation Test ◽  
Accelerated Degradation Test ◽  
The Relationship

Aiming at electrical contact degradation behavior of beryllium bronze in storage, electrical contact accelerated degradation test was made. Choosing contact resistance as the performance degradation sensitive parameter, studied its degradation behavior by testing contact resistance of beryllium bronze under different temperature after different oxidized times. The result shows that the relationship between contact resistance and oxidized time is exponential and the lifetime of beryllium bronze samples at normal stress is 24.4 years when failure threshold is 100 mΩ and confidence is 95%, which is predicted by Arrhenius model related to temperature.

scholarly journals Импульсное намагничивание короткозамкнутой катушки из ВТСП

2019 ◽  
Vol 89 (8) ◽  
pp. 1208
Author(s):  
П.А. Бражник ◽  
А.А. Картамышев ◽  
В.С. Коротков ◽  
Е.П. Красноперов ◽  
А.А. Бишаев ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Fold Increase ◽  
Voltage Characteristic ◽  
Copper Coating ◽  
Current Voltage Characteristic ◽  
Trapped Field ◽  
Pulsed Heating ◽  
Initial Stage ◽  
Current Voltage ◽  
2G Tape

In this paper is described the pulsed magnetization of a 20-turn short-circuited coil from a stabilized HTSC-2G tape. The trapped field in the coil is close to the value obtained at the field cooling (FC) process and varies only slightly with a 5-fold increase in the amplitude of the magnetizing pulse. The copper coating of the tape significantly reduces the effects of pulsed heating. The relaxation of the current in the initial stage is determined by the flow of current between the superconducting and normal layer and the type of the current-voltage characteristic. At large times (t> 100 s), attenuation is determined by the contact resistance of the junction.

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