An Analytical and Experimental Study of Plasma Spraying of Alumina

1988 ◽  
Vol 121 ◽  
Author(s):  
D. J. Varacalle
Keyword(s):  
Experimental Study ◽  
Plasma Spraying ◽  
Numerical Models ◽  
Power Level ◽  
Hydrogen Gas ◽  
Physical Processes ◽  
Particle Injection ◽  
Alumina Particles ◽  
Temperature And Flow Fields

ABSTRACTAs part of an investigation of the dynamics that occur in the plume of a typical thermal spray torch, an analytical and experimental study of the plasma spraying of alumina is being performed; preliminary results are reported here. Numerical models of the physical processes in the torch column and plume were used to determine the temperature and flow fields. Computer simulations of particle injection (15, 34, and 53 μm alumina particles) are also presented. The alumina experiments were conducted at a 35 kW power level using a 100 scfh argon and 15 scfh hydrogen gas mixture for two alumina powders. The quality of the coatings is discussed with respect to porosity, sample metallography, and microhardness.

Plasma Spraying of Zirconia Coatings

1989 ◽  
Vol 155 ◽  
Author(s):  
D. J. Varacalle ◽  
G. R. Smolik ◽  
G. C. Wilson ◽  
G. Irons ◽  
J. A. Walter
Keyword(s):  
Gas Flow ◽  
Analytical Study ◽  
Numerical Models ◽  
Fractional Factorial ◽  
Spray Parameters ◽  
X Ray Diffraction ◽  
Physical Processes ◽  
Particle Injection ◽  
Carrier Gas Flow ◽  
Temperature And Flow Fields

ABSTRACTAs part of an investigation of the dynamics that occur in the plume of a thermal spray torch, an experimental and analytical study of the deposition of yttria-stabilized zirconia has been accomplished. Experiments were conducted using a Taguchi fractional factorial design. Nominal spray parameters were: 900 A, 36 kW, 100 scfh argon primary gas flow, 47 scfh helium secondary gas flow, 11.5 scfh argon powder carrier gas flow, 3.5 lb/h powder feed rate, 3 in. spray distance, and an automated traverse rate of 20 in./s. The coatings were characterized for thickness, hardness, and microstructural features with optical microscopy, scanning electron microscopy, and x-ray diffraction. Attempts are made to correlate the features of the coatings with the changes in operating parameters. Numerical models of the physical processes in the torch column and plume were used to determine the temperature and flow fields. Computer simulations of particle injection (10 to 75 μm zirconia particles) are presented.

Improvements in General Circulation Model performance in simulating Antarctic climate

1990 ◽  
Vol 2 (4) ◽  
pp. 287-300 ◽  
Author(s):  
Ian Simmonds
Keyword(s):  
Special Reference ◽  
General Circulation Model ◽  
General Circulation ◽  
Numerical Models ◽  
Model Performance ◽  
Circulation Model ◽  
General Circulation Models ◽  
Physical Processes ◽  
Steady Improvement

Increasingly, many aspects of the study of Antarctica and the high southern latitudes are being aided by various types of numerical models. Among these are the General Circulation Models (GCMs), which are powerful tools that can be used to understand the maintenance of present atmospheric climate and determine its sensitivity to imposed changes. The changes in the ability of GCMs used over the last two decades to simulate aspects of atmospheric climate at high southern latitudes are traced and it is concluded there has been a steady improvement in model products. The task of assessing model climates in high southern latitudes is made difficult by the uncertainties in the data used for the climatological statistics. It is suggested that the quality of the climates produced by most modern GCMs in many aspects cannot be said to be poor, especially considering the uncertainties in ‘observed’ climate. There is obviously need for improvements in both modelling and observations. Finally, some topics are highlighted in which the formulation of models could be improved, with special reference to better treatment of physical processes at high southern latitudes.

scholarly journals Influence of Parameterization of Soil Processes on Meteorological Forecasts of Vertical Profiles

2016 ◽  
Vol 23 (3) ◽  
pp. 493-503 ◽  
Author(s):  
Grzegorz Duniec ◽  
Andrzej Mazur
Keyword(s):  
Numerical Models ◽  
Water Flux ◽  
Weather Forecast ◽  
Bare Soil ◽  
Expected Improvement ◽  
Physical Processes ◽  
Meteorological Model ◽  
Numerical Weather ◽  
Numerical Weather Forecast

Abstract Soil and atmosphere boundary layer (ABL) interact with each other and influence physical processes in soil and atmosphere. Quality of numerical weather forecast depends on good mapping of complex soil process (microphysics processes in soil, fluid dynamics in porous media, soil dynamics, water cycle in soil and soil-plant-water relation, thermal processes in the soil etc.) in parameterization soil schemes. Current parameterizations of soil physical processes in TERRA_ML (multilayer soil module of the COSMO meteorological model) were prepared 30 years ago for numerical model with poor resolution. Nowadays operationally numerical models work with much better resolution. So, previous parameterization must have been improved or prepared from the beginning if it is expected improvement quality of numerical weather forecast. The influence of changing parameterization of water flux through the soil for “bare soil” case on vertical meteorological profiles is presented in this paper. This influence can be seen not only in weather forecasts, but also in any areas where the results of meteorological model(s) are used, like decision support systems in emergency situations or modeling of dispersion of air pollutants.

Analisis Soal Matematika Tipe Higher Order Thinking Skills (HOTS) Tingkat SMP

2020 ◽  
Vol 2 (2) ◽  
pp. 112-129
Author(s):  
Lelly Oktafiana ◽  
Iis Holisin ◽  
Himmatul Mursyidah
Keyword(s):  
Power Level ◽  
Thinking Skills ◽  
Higher Order Thinking Skills ◽  
National Examination ◽  
Class Viii ◽  
Valid Test ◽  
Grade Material ◽  
Data Collection Technique ◽  
High Level

This study aims to describe the quality of the 2018 Mathematics National Examination (UN) in the HOTS types at the junior high level in terms of the level of validity, reliability, problem differentiation power, level of difficulty and distractor. This type of research is a descriptive study. The research was conducted at SMP Muhammadiyah 4 Surabaya and SMP Negeri 13 Surabaya for students in class VIII. The data collection technique used is a test. The test was taken from the 2018 math UN questions in odd semester VIII grade material including HOTS type. The number of UN mathematics questions in 2018 in the odd semester VIII class material consisted of 12 questions with 25% including LOTS types and 75% including HOTS types. The results showed: (1) 100% valid test questions, (2) high question reliability, (3) good problem differentiation power, (4) the difficuly level of the question 77,77% categorized as moderate and 2 question 22,23% are categorized as difficult, (5) there are 2 questions with one of the answer options do not work.

A Survey of the Present State of Friction Modelling in the Analytical and Numerical Investigation of Brake Noise Generation

1999 ◽  
Author(s):  
Jörg Wallaschek ◽  
Karl-Heinz Hach ◽  
Ulrich Stolz ◽  
Parimal Mody
Keyword(s):  
Friction And Wear ◽  
Numerical Models ◽  
Engineering Practice ◽  
Noise Generation ◽  
Noise And Vibration ◽  
Levels Of Detail ◽  
Key Issues ◽  
Brake Noise ◽  
Automotive Brake

Abstract Noise and vibration have become key issues in the design of automotive braking systems. Efforts to improve present day braking systems must take noise and vibration behaviour into account. Good knowledge of the mechanisms involved in the generation of brake noise has thus become an important competitive factor in the design of automotive brake systems. The present paper summarizes some facts and hypotheses concerning the generation of brake noise. First the different brake noise phenomena are classified. Then several approaches, including models of various levels of detail which have been suggested to explain the root causes of brake noise generation are discussed in detail. It will be pointed out that friction and wear processes at the interface of brake pad and rotor play an important role in the understanding of brake noise generation. Unfortunately, our present day knowledge on these processes is quite limited. Further research of basic processes is still needed to improve the quality of analytical and numerical models of friction and wear processes, before reliable predictions of brake noise generation become possible. Based on a discussion of simple models frequently used in engineering practice, guidelines for further research in tribological modelling of the interface processes in pad/rotor interaction will be formulated.

The Potential Effect of Mucuna pruriens Seed Extract on Sperm Quality experimental study on mice exposed to cigarette smoke

2021 ◽  
Vol 20 (4) ◽  
pp. 768-773
Author(s):  
Meidona Nurul Milla ◽  
Yani Istadi ◽  
Vania Shaula ◽  
Deastri Anjeas Wari ◽  
Chntyia Dwi Cahyani Puspitasari ◽  
...  
Keyword(s):  
Experimental Study ◽  
Cigarette Smoke ◽  
Sperm Quality ◽  
Medical Science ◽  
Seed Extract ◽  
Reproductive Age ◽  
Testicular Atrophy ◽  
Mucuna Pruriens ◽  
Control Group

Background: Infertility has been more common problems among couple of reproductive age. One of the factors causing this disorder is unhealthy environmental factors including exposure to cigarette smoke. Polynuclear aromatic hydrocarbons (PAHs) in cigarette smoke can cause testicular atrophy, while the free radicals can inhibit the stages of spermatogenesis, and nicotine in cigarettes affects the brain dopamine levels affecting the levels of GnRH, and subsequently affect the levels of FSH and LH needed in spermatogenesis. The use of Mucuna pruriens seed extract containing antioxidants and L-dopa is expected to improve the quality of sperm after exposure to cigarette smoke. Objective: This study aimed to determine the effect of Mucuna pruriens seed extract on the sperm quality in mice exposed to cigarette smoke. Methods: This study was an experimental study with a post test only control group design. A total of 20 mice were divided into 4 groups of five mice each. All groups were exposed to cigarette smoke. Group 1 was the negative control exposed to cigarette smoke. Groups 2, 3, 4 were exposed to cigarettes smoke and given Mucuna pruriens seed extracts at the dose of 250; 300; and 350 mg/Kg BW/day. Parameters of sperm quality included concentration, morphology, motility and viability. Results: Post hoc tests showed there were significant differences among treatment groups. Conclusion: the administration of Mucuna pruriens seed extract affects the sperm quality of BALB/c mice exposed to cigarettes smoke. Bangladesh Journal of Medical Science Vol.20(4) 2021 p.768-773

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