scholarly journals INVESTIGATION OF INFLUENCE OF TECHNOLOGICAL IMPURITIES ON THE I–V CHARACTERISTICS OF THE BIPOLAR n–p–n-TRANSISTOR

2018 ◽  
Vol 63 (2) ◽  
pp. 244-249
Author(s):  
V. B. Odzhaev ◽  
A. K. Panfilenko ◽  
A. N. Pyatlitski ◽  
V. S. Prosolovich ◽  
S. V. Shvedau ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Reverse Current ◽  
Substrate Material ◽  
Physical Characteristics ◽  
Similar Process ◽  
Physical Parameters ◽  
Operational Parameters ◽  
High Concentration ◽  
Collector Junction ◽  
Basic Characteristics

Contamination of the monocrystal silicon with technological impurities in the devices fabrication process exerts a considerable influence on the electro-physical characteristics of the bipolar n–p–n-transistors. Revelation of the causes of the labile reproducibility of the basic characteristics of the bipolar planar n–p–n-transistors is vital for the purpose of establishing the factors, determining reliability and stability of the operational parameters of the integrated circuits. There were investigated I–V characteristics of the various lots of the bipolar n–p–n-transistors, fabricated under the epitaxialplanar technology as per the similar process charts with the identical used technological materials, however, at different times. It is established that the electro-physical characteristics of the bipolar n–p–n-transistors substantially depend on the contents of the technological impurities in the substrate material. Availability of the high concentration of the generation-recombination centers, related to the metallic impurities, results both in increase of the reverse current of the collector – base junction of the transistors and the significant reduction of the breakdown voltage of the collector junction. The most probable cause of deterioration of the electro-physical parameters of the bipolar n–p–n-transistors is the material contamination with the technological impurities (such, as Fe, Cl, Ca, Cu, Zn and others) during the production process of the devices fabrication. The sources of impurity may be both the components and sub-assemblies of the technological units and the materials and reagents under usage.

scholarly journals Astrometry of the solar system: the ground-based observations

2007 ◽  
Vol 3 (S248) ◽  
pp. 66-73
Author(s):  
J.-E. Arlot
Keyword(s):  
Solar System ◽  
Space Missions ◽  
Physical Characteristics ◽  
Physical Parameters ◽  
Dynamical Models ◽  
Long Period ◽  
Solar System Objects ◽  
Different Characteristics

AbstractThe main goal of the astrometry of solar system objects is to build dynamical models of their motions to understand their evolution, to determine physical parameters and to build accurate ephemerides for the preparation and the exploitation of space missions. For many objects, the ground-based observations are still very important because radar or observations from space probes are not available. More, the need of observations on a long period of time makes the ground-based observations necessary. The solar system objects have very different characteristics and the increase of the astrometric accuracy will depend on the objects and on their physical characteristics. The purpose of this communication is to show how to get the best astrometric accuracy.

scholarly journals Gas Permeation Characteristics across Nano-Porous Inorganic Membranes

1970 ◽  
Vol 5 (2) ◽  
Author(s):  
M.R Othman, H. Mukhtar ◽  
A.L. Ahmad
Keyword(s):  
Pore Size ◽  
Membrane Surface ◽  
Porous Ceramic ◽  
Knudsen Diffusion ◽  
Gas Permeation ◽  
Physical Characteristics ◽  
Inorganic Membrane ◽  
Molecular Characteristics ◽  
Inorganic Membranes ◽  
Operational Parameters

An overview of parameters affecting gas permeation in inorganic membranes is presented. These factors include membrane physical characteristics, operational parameters and gas molecular characteristics. The membrane physical characteristics include membrane materials and surface area, porosity, pore size and pore size distribution and membrane morphology. The operational parameters include feed flow rate and concentration, stage cut, temperature and pressure. The gas molecular characteristics include gas molecular weight, diameter, critical temperature, critical pressure, Lennard-Jones parameters and diffusion volumes. The current techniques of material characterization may require complementary method in describing microscopic heterogeneity of the porous ceramic media. The method to be incorporated in the future will be to apply a stochastic model and/or fractal dimension. Keywords: Inorganic membrane, surface adsorption, Knudsen diffusion, Micro-porous membrane, permeation, gas separation.

Ohmic and viscous dissipation effects on micropolar non-Newtonian nanofluid Al2O3 flow through a non-Darcy porous media

2022 ◽  
pp. 1-13
Author(s):  
Nabil T. Eldabe ◽  
Mohamed Y. Abou zeid ◽  
Sami M. El Shabouri ◽  
Tarek N. Salama ◽  
Aya M. Ismael
Keyword(s):  
Magnetic Field ◽  
Heat Source ◽  
Numerical Solutions ◽  
Tangential Velocity ◽  
Darcy Number ◽  
Physical Parameters ◽  
Fluid Temperature ◽  
High Concentration ◽  
Ohmic Dissipation ◽  
Similarity Transformations

Inclined uniform magnetic field and mixed convention effects on micropolar non-Newtonian nanofluid Al2O3 flow with heat transfer are studied. The heat source, both viscous and ohmic dissipation and temperature micropolarity properties are considered. We transformed our system of non-linear partial differential equations into ordinary equations by using suitable similarity transformations. These equations are solved by making use of Rung–Kutta–Merson method in a shooting and matching technique. The numerical solutions of the tangential velocity, microtation velocity, temperature and nanoparticle concentration are obtained as functions of the physical parameters of the problem. Moreover, we discussed the effects of these parameters on the numerical solutions and depicted graphically. It is obvious that these parameters control the fluid flow. It is noticed that the tangential velocity magnifies with an increase in the value of Darcy number. Meanwhile, the value of the tangential velocity reduces with the elevation in the value of the magnetic field parameter. On the other hand, the elevation in the value of Brownian motion parameter leads to a reduction in the value of fluid temperature. Furthermore, increasing in the value of heat source parameter makes an enhancement in the value of nanoparticles concentration. The current study has many accomplishments in several scientific areas like medical industry, medicine, and others. Therefore, it represents the depiction of gas or liquid motion over a surface. When particles are moving from areas of high concentration to areas of low concentration.

On the Formation of Ultrathin Simox Structures by Low Energy Implantation

1992 ◽  
Vol 284 ◽  
Author(s):  
F. Namavar ◽  
B. Buchanan ◽  
N. M. Kalkhoran
Keyword(s):  
Integrated Circuits ◽  
Substrate Material ◽  
Low Energy ◽  
Silicon On Insulator ◽  
Great Promise ◽  
Ultrathin Layers ◽  
Commercial Applications ◽  
Competitive Substrate ◽  
The Cost ◽  
Radiation Hard

ABSTRACTSilicon-on-insulator (SOI) wafers made by standard energy (150–200 keV) Separation by IMplantation of Oxygen (SIMOX) processes have shown great promise for meeting the needs of radiation-hard microelectronics. However, if SIMOX material is to become a competitive substrate material for manufacturing commercial integrated circuits, the cost of the SIMOX wafers must be greatly reduced. The low energy SIMOX (LES) process accomplishes the needed reduction in cost by producing ultrathin layers which require much lower ion doses. These ultrathin layers are necessary for the next generation of commercial ultra high density CMOS integrated circuits, and must be of very high quality to be utilized for commercial applications. In this paper we discuss characterization of ultrathin LES structures.

An Extra Mode of Enhanced Heat Transfer by Oscillating Bubbles in Minichannels and Microchannels

2003 ◽  
Author(s):  
J. J. Schro¨der ◽  
S. Alraun
Keyword(s):  
Heat Transfer ◽  
High Speed ◽  
Bulk Water ◽  
Electrical Heating ◽  
Similar Process ◽  
Experimental Investigations ◽  
Physical Parameters ◽  
Two Phase ◽  
Model Calculations ◽  
Zero Crossing

Experimental investigations on heat transfer in tubular micro- or minichannel arrangements more often report on two-phase flow instabilities, pulsations or oscillations, which result in a remarkable influence on heat transfer efficiency. In order to explain the piston-like oscillations of the steam-plugs and water-slugs (-columns), the authors studied the somehow similar process which occurs in the worldwide known toy steam boat. Experiments have been performed which used a demonstration plant made of glass. By controlled electrical heating, high-speed video, pressure and local temperature measurements, the paths of energy have been disclosed. The results are as surprising as the effect of making gold from sand with respect to an equivalent axial heat-conductivity of the water-filled glass tube. Initiated by these results, an abstracting model is presented that analytically quantifies this new regenerating (oscillating and conducting) heat transfer mode e.g. concerning the combination of a heat recharging tube wall and an oscillating water column in a field of diminishing temperatures between the temperature of the boiler surface and the subcooled bulk water. By introducing these heat transfer details, the steam boat can give an answer, not only on frequency and amplitude of the oscillations, but on the steady state conditions for — or time-dependency of — the location of zero-crossing as well. Experimental results and model calculations are in good agreement and need no fitting factors. This is the base to discuss that process along with its physical parameters and compare it to the above mentioned observations in flow-boilers or pulsating heat pipes etc. which use microchannels or minichannels.

Microthrix parvicella foaming at the Fusina WWTP

2002 ◽  
Vol 46 (1-2) ◽  
pp. 499-502 ◽  
Author(s):  
P. Miana ◽  
L. Grando ◽  
G. Caravello ◽  
M. Fabris
Keyword(s):  
Activated Sludge ◽  
Microscopic Observation ◽  
Industrial Wastewater ◽  
The Other ◽  
Physical Parameters ◽  
High Concentration ◽  
Strong Connection ◽  
Mixed Liquor ◽  
Microthrix Parvicella

The Fusina WWTP receives civil and industrial wastewater from Venice and its hinterland. Its treatment capacity is in the range of 4,000–5,000 m3/h. In winter the Fusina WWTP is subjected to brown and viscous foams developed on the surface of the aeration basins and of the clarifiers. The microscopic observation of biological foams and activated sludge samples showed high concentration of the filamentous organism Microthrix parvicella. This paper investigates the growth of M. parvicella from January 1998 to January 1999 and relates it to foams developed on the aeration basins and clarifiers, to temperature, surfactants, BOD5, NH4, NO3, NO2, DO, PO4 and pH of the wastewater influent, to SVI and the other species of filamentous organisms of mixed liquor. The results demonstrate the strong connection of the foams developed with M. parvicella abundance, the synergic action with surfactants, the dependence of M. parvicella on temperature and no relation to the other chemical and physical parameters investigated.

Computational Analysis of Nanofluid Cooling of High Concentration Photovoltaic Cells

2014 ◽  
Vol 6 (3) ◽  
Author(s):  
Z. Xu ◽  
C. Kleinstreuer
Keyword(s):  
Reynolds Number ◽  
Energy Use ◽  
Volume Fraction ◽  
Cooling System ◽  
Optimal Parameter ◽  
Photovoltaic Cells ◽  
System Efficiency ◽  
Operational Parameters ◽  
High Concentration ◽  
Temperature Range

High concentration photovoltaic devices require effective heat rejection to keep the solar cells within a suitable temperature range and to achieve acceptable system efficiencies. Various techniques have been developed to achieve these goals. For example, nanofluids as coolants have remarkable heat transfer characteristics with broad applications; but, little is known of its performance for concentration photovoltaic cooling. Generally, a cooling system should be designed to keep the system within a tolerable temperature range, to minimize energy waste, and to maximize system efficiency. In this paper, the thermal performance of an Al2O3-water cooling system for densely packed photovoltaic cells under high concentration has been computationally investigated. The model features a representative 2D cooling channel with photovoltaic cells, subject to heat conduction and turbulent nanofluid convection. Considering a semi-empirical nanofluid model for the thermal conductivity, the influence of different system design and operational parameters, including required pumping power, on cooling performance and improved system efficiency has been evaluated. Specifically, the varied system parameters include the nanoparticle volume fraction, the inlet Reynolds number, the inlet nanofluid temperature, and different channel heights. Optimal parameter values were found based on minimizing the system's entropy generation. Considering a typical 200-sun concentration, the best performance can be achieved with a channel of 10 mm height and an inlet Reynolds number of around 30,000, yielding a modest system efficiency of 20%. However, higher nanoparticle volume fractions and lower nanofluid inlet temperatures further improve the cell efficiency. For a more complete solar energy use, a combined concentration photovoltaic and thermal heating system are suggested.

scholarly journals Retorting conditions affect palatability and physical characteristics of canned cat food

2017 ◽  
Vol 6 ◽  
Author(s):  
Esther A. Hagen-Plantinga ◽  
Denmark F. Orlanes ◽  
Guido Bosch ◽  
Wouter H. Hendriks ◽  
Antonius F. B. van der Poel
Keyword(s):  
Particle Size ◽  
Physicochemical Properties ◽  
Physicochemical Characteristics ◽  
Physical Characteristics ◽  
Physical Parameters ◽  
Time Profiles ◽  
Temperature Time

AbstractThe effects of different temperature and time conditions during retorting of canned cat food on physicochemical characteristics and palatability were examined. For this purpose, lacquer cans containing an unprocessed loaf-type commercial cat food were heated in a pressurised retorting system at three specified temperature–time profiles (113°C/232 min, 120°C/103 min and 127°C/60 min) to equal a similar lethality (F0 value = 30). Physicochemical properties (viscosity, texture, particle size, pH) were determined, and a 10 d three-bowl palatability test was performed with ten European shorthair cats. Retorting at 113°C/232 min resulted in differences in all the physical parameters examined (<viscosity, firmness, adhesiveness, and > particle size). Significant pH differences were observed (6·53, 6·63 and 6·66 for T113/232, 120 and 127°C, respectively). Preference ratios were 0·38, 0·31 and 0·31 for T113/232, 120 and 127°C, respectively (P = 0·067). It can be concluded that different retorting temperature–time profiles with equal F0 value significantly affect physical characteristics and tended to affect palatability of moist cat food.

scholarly journals Impacts of Instrument Limitations on Estimated Raindrop Size Distribution, Radar Parameters, and Model Microphysics during Mei-Yu Season in East China

2017 ◽  
Vol 34 (5) ◽  
pp. 1021-1037 ◽  
Author(s):  
Long Wen ◽  
Kun Zhao ◽  
Guifu Zhang ◽  
Su Liu ◽  
Gang Chen
Keyword(s):  
Rain Gauge ◽  
Rainfall Amount ◽  
East China ◽  
Physical Parameters ◽  
High Concentration ◽  
Derived Relations ◽  
Raindrop Size Distribution ◽  
Accretion Rates ◽  
Raindrop Size ◽  
Microphysical Processes

AbstractInstrumentation limitations on measured raindrop size distributions (DSDs) and their derived relations and physical parameters are studied through a comparison of the DSD measurements during mei-yu season in east China by four collocated instruments, that is, a two-dimensional video disdrometer (2DVD), a vertically pointing Micro Rain Radar (MRR), and two laser-optical OTT Particle Size Velocity (PARSIVEL) disdrometers (first generation: OTT-1; second generation: OTT-2). Among the four instruments, the 2DVD provides the most accurate DSD and drop velocity measurements, so its measured rainfall amount has the best agreement with the reference rain gauge. Other instruments tend to miss more small drops (D < 1 mm), leading to inaccurate DSDs and a lower rainfall amount. The low rainfall estimation becomes significant during heavy rainfall. The impacts of instrument limitations on the microphysical processes (e.g., evaporation and accretion rates) and convective storm morphology are evaluated. This is important especially for mei-yu precipitation, which is dominated by a high concentration of small drops. Hence, the instrument limitations need to be taken into account in both QPE and microphysics parameterization.

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