Journal articles on the topic 'Make-out coefficient'
To see the other types of publications on this topic, follow the link: Make-out coefficient.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Make-out coefficient.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Li, Ting, Qing Jia, and Zhi Gang Yang. "The Influence of Rotating Wheels on Vehicle Aerodynamics." Applied Mechanics and Materials 246-247 (December 2012): 543–47. http://dx.doi.org/10.4028/www.scientific.net/amm.246-247.543.
Full textAbstract:
Full scaled simplified model and production vehicle were applied to make a research on the local and global flow characteristics. Two different conditions including stationary and rotation were employed in computational simulation by steady RNS Navier-Stokes calculation. Further, detailed analysis on flow, surface pressure coefficient, drag coefficient and lift coefficient affected by rotating wheel figure out that rotating wheel has a significant influence on the flow around wheel and vehicle. Pressure difference, drag coefficient and lift coefficient are decreased by rotation, which improve aerodynamic performance.
2
Susanto, Chyntia, Helen Leonora, and Carmel Meiden. "META ANALISIS: DETERMINAN EARNINGS RESPONSE COEFFICIENT PADA BEBERAPA PENELITIAN SKRIPSI DI INDONESIA." Jurnal Proaksi 9, no. 2 (May 10, 2022): 127–43. http://dx.doi.org/10.32534/jpk.v9i2.2743.
Full textAbstract:
Investors need information, one of which is the company's accounting profit figures shown in its financial statements, to make investment decisions. The information is good or bad news that generates various investor responses, and underlies the earnings response coefficient research. Research on the determinants of earning response coefficients has been widely carried out with different research results. This study aims to organize and find the consistency of the results of previous studies. The object of the research is a thesis on the determinants of earning response coefficient with a research period of 2011-2019. The data collection technique used is the observation technique and the sample selection technique used is the purposive sampling technique, and uses meta-analysis as a research analysis technique. The results of this study indicate that earnings persistence, capital structure, firm size, corporate social responsibility disclosure, profitability, and leverage affect the earning response coefficient.
3
Dong, Xianshan, Qinwen Huang, Junhua Zhu, Wei Xu, and Ping Lai. "Effect of excitation voltage on bias temperature coefficient of MEMS sandwich accelerometer." International Journal of Modern Physics B 33, no. 12 (May 10, 2019): 1950112. http://dx.doi.org/10.1142/s0217979219501121.
Full textAbstract:
In MEMS closed-loop accelerometer, excitation voltage is an important design parameter that is related to many performance indexes, and the bias temperature coefficient is a key point for MEMS accelerometer. But the effect of excitation voltage on bias temperature coefficient is not clear and their relation has not yet been established. This paper studies the effect of excitation voltage on bias temperature coefficient of MEMS sandwich accelerometer. The mechanism of their relation is point out, and experiments of bias temperature drift with different excitation voltages are carried out. The measured results show that the excitation voltage influences the bias temperature coefficient of MEMS sandwich accelerometer greatly, and the frame of sensor structure is the main source of bias temperature drift in MEMS sandwich accelerometer. This paper is also helpful for researchers to further understand the source of bias drift in MEMS sandwich accelerometer and make corresponding improvement.
4
Wang, Liyan, Jiatao Yan, Qi Wang, Binghui Wang, and Aimable Ishimwe. "Study on Permeability of Steel Slag and Steel Slag Modifying Silt Soil as New Geo-Backfill Materials." Advances in Civil Engineering 2019 (July 1, 2019): 1–14. http://dx.doi.org/10.1155/2019/5370748.
Full textAbstract:
To make steel slag being reasonably used in geotechnical backfilling projects or soft foundation treatment projects, three kinds of steel slag such as fine, coarse, and gravel steel slag were studied through particle analysis tests, relative density tests, and specific gravity tests to obtain basic physical parameters. Considering the influence of relative density, gradation, and other factors, constant head permeability tests of pure steel slag and variable head permeability tests of modified silt soil with different mixing contents of steel slag were carried out to test permeability coefficients under various working conditions. Prediction formulas on the permeability coefficients of the three kinds of pure steel slag and steel slag-treated silt soil were, respectively, deduced. It was concluded that the permeability coefficient of pure steel slag was greatly influenced by particle size and relative density, similar to the case of permeability coefficients of fly ash and fine sand in their dense states, and the larger the relative density was, the smaller the permeability coefficient was. The permeability coefficient of steel slag-treated silt soil increased with increasing of mixing content of steel slag, showing that steel slag can obviously improve the permeability performance of silt soil. Research results provide reference for design and construction on the application of steel slag in roadbed backfill, steel slag modifying silt soil, and other projects.
5
Kuznetsov, A. V., A. A. Igolkin, A. I. Safin, and A. O. Pantyushin. "Mathematical model of acoustic characteristics of polyurethane foam used for sound absorption in aerospace engineering." VESTNIK of Samara University. Aerospace and Mechanical Engineering 20, no. 2 (July 9, 2021): 53–62. http://dx.doi.org/10.18287/2541-7533-2021-20-2-53-62.
Full textAbstract:
When solving the problem of reducing the acoustic load on the spacecraft during the launch and flight of the launch vehicle, finite element modeling of acoustic processes under the nose fairing is carried out. To successfully solve this problem, a mathematical model of the acoustic characteristics of the material used for sound insulation is required. The existing mathematical models of the acoustic characteristics of materials are not suitable for the material under consideration that can be used in rocket and space technology to increase the sound insulation of the payload fairing + transfer compartment assembly. To obtain the sound absorption coefficient of the material, an impedance tube measurement method with two microphones is used. Using the method of differential evolution, the coefficients of a mathematical model of acoustic characteristics of the Delany-Bazley type for the specified material are selected. The sound absorption coefficient obtained experimentally and that calculated using the obtained model are compared; the average and maximum values of the error are shown. The resulting model will make it possible to carry out finite element modeling of acoustic and vibroacoustic processes under the nose fairing, taking into account the location of the sound-absorbing material.
6
Xie, Zhuojie, Yuhui Wang, and Qingxian Wu. "Battle damage assessment of surface warship formation based on improved gray relational analysis." Journal of Defense Modeling and Simulation: Applications, Methodology, Technology 15, no. 3 (November 1, 2017): 269–78. http://dx.doi.org/10.1177/1548512917740446.
Full textAbstract:
The paper analyzes the pros and cons of classical gray relational analysis on solving multi-target and multi-attribute problems, and presents an improved gray relational model to assess the battle damage of surface warship formations. First, with an entropy method and analytic hierarchy process, the subjective and objective weights of the index attributes are determined, respectively, and then they are combined with the product method to obtain the combined weight. Second, to make full use of the information carried by the index attributes, a polygon area formed by the adjacent points of the reference sequence curve and alternative sequence curve is used as gray relational coefficient. Third, by combining with the combined weight and the gray relational coefficients, an improved gray relational degree is thus determined. Finally, the numerical results illustrate that the battle damage assessment is generally consistent with the assessment results of experts, and the achieved result will provide important information to make a correct decision for carrying out a next strike.
7
CUMMINGS, PETER, and XIAOBING FENG. "SHARP REGULARITY COEFFICIENT ESTIMATES FOR COMPLEX-VALUED ACOUSTIC AND ELASTIC HELMHOLTZ EQUATIONS." Mathematical Models and Methods in Applied Sciences 16, no. 01 (January 2006): 139–60. http://dx.doi.org/10.1142/s021820250600108x.
Full textAbstract:
We consider complex-valued acoustic and elastic Helmholtz equations with the first order absorbing boundary condition in a star-shaped domain in ℜN for N ≥ 2. It is known that the elliptic regularity coefficients depend on the frequency ω, and have singularities for both zero and infinite frequency. In this paper, we obtain sharp estimates for the coefficients with respect to large frequencies. It is proved that the elliptic regularity coefficients are bounded by first or second order polynomials in ω for large ω. The crux of our analysis is to establish and make use of Rellich identities for the solutions to the acoustic and elastic Helmholtz equations. Our results improve the earlier estimates of Refs. 10 and 11, which were carried out based on layer potential representations of the solutions of the Helmholtz equations.
8
Irawan, Irawan, and Aqli Mursadin. "ANALISIS KINERJA AIR HEATER DI PLTU ASAM-ASAM UNIT 2." JTAM ROTARY 1, no. 1 (April 1, 2019): 17. http://dx.doi.org/10.20527/jtam_rotary.v1i1.1396.
Full textAbstract:
Indonesia as one of the largest coal producers utilizes this advantage by establishing a steam power plant, one of which is Borneo south PLTU power plant PT.PLN (persero) south of Borneo and Central Borneo Asam-Asam generation sector. One important component of PLTU is air heater to raise the combustion air temperature. Initial heating of ljungstrom type lattest regenerative air heater in PLTU Asam-Asam unit 2 is carried out cleaning and maintenance on seal and gas side surfaces to optimize heat transfer coefficient and ratio of air intake ratio exposed by forced draft fan and air heated by flue gas in heater air heater elements and transferred to the combustion chamber to make efficient use of new fuel. Measurements were carried out on August 9, 2017 for 2 hours to find out the average value of heat transfer coefficient and temperature comparison of entry and exit from air heater of Asam-Asam unit 2 steam power plant. This research was conducted to find out the value of heat transfer coefficient and air temperature ratio with measurement on the inlet and outlet for two hours. The results of the air heater performance analysis in in PLTU Asam-Asam unit 2 steam power plant in terms of the highest heat transfer coefficient was 62.75 W/m^2.℃ at 2:04 PM, while the lowest heat transfer coefficient was 62.37 W/m^2.℃ at 3:10 PM, and the average heat transfer coefficient is 62.50 W/m^2.℃ . While the highest water heater ratio 9.70 at 3:44 PM and the lowest ratio 8.32 at minute 3:09 PM, and the average water heater ratio 9.01. Heater water heater elements in good condition and performance in receiving and releasing heat. Keywords: Air Heater, Heat Transfer Coefficient, Temperature Ratio, Heating Elements
9
Гавлина, Ольга Тихоновна, Сергей Игоревич Каргов, and Владимир Александрович Иванов. "The concept of gel diffusion in the kinetics of swelling and shrinking of a polystyrene sulfonic acid ion exchanger in the K+ form." Сорбционные и хроматографические процессы 21, no. 6 (January 8, 2022): 794–804. http://dx.doi.org/10.17308/sorpchrom.2021.21/3824.
Full textAbstract:
The kinetics of swelling and shrinking of polystyrene resins of the sulfonic acid type was investigated. The ion-exchange bead in the K+ form, equilibrated with a 0.1 M, 0.5 M, 1.0 M or 2 M KCl solution was placed into water and its diameter was measured continuously. In the reverse experiments, the bead, which came into equilibrium with water, was transferred into KCl solutions and the kinetics of grain shrinking was studied analogously. The experimental data were processed by using the theory of "gel diffusion", the parameter of which is the so-called gel diffusion coefficient, similar to the molecular diffusion coefficient. In contrast to previously published works, in which only the first term of the series in the corresponding equation was taken into account, in our work the first ten members of the series were taken into account. It turned out that it is necessary to take into account not only the first member of the series (as was done in previously published works), but also the second member of the series. It also turned out that the values of the obtained gel diffusion coefficient, obtained by this method, quite logically increased somewhat during the process of swelling (for example, in experiments with 1 M KCl from 2.1×10−6 to 3.0×10−6 cm2/s) and decreased somewhat during the process of shrinking. It was shown that the average values of the diffusion coefficients of the gel make it possible to adequately describe the main part of the kinetic curve. The concept of gel diffusion allows comparing the swelling kinetics of various polyelectrolyte gels in terms of diffusion coefficients, regardless of the particle shape, systematize data for various materials, and comparing their properties with the molecular diffusion of other substances.
It also turned out that in the very final parts (5-10%) of the kinetic curves a sharp decrease in the diffusion coefficient value was observed both in experiments with the swelling and shrinking of grains. It indicates that during the final stages there was a sharp deceleration of the process due to a change in its mechanism.
10
GUO, SHENG-LI, ZHUN GUO, T. SUSDORF, and TIAN-DE CAO. "ABSORPTION, EMISSION AND NONLINEAR SPECTROSCOPIC CHARACTERIZATION OF REACTIVE DYE." Journal of Nonlinear Optical Physics & Materials 15, no. 04 (December 2006): 481–90. http://dx.doi.org/10.1142/s0218863506003414.
Full textAbstract:
An optical spectroscopic characterization is carried out on a reactive dye (reactive orange 1). This dye is widely applied in textile coloration. It is a potential candidate for photonics applications. Its absorption cross-section spectra are measured. A fluorescence spectroscopic characterization is undertaken by measuring the fluorescence quantum distributions and fluorescence quantum yields. The saturable absorption is studied by nonlinear transmission measurements with intense picosecond laser pulses (second harmonic pulses of a mode-locked Nd :glass laser). The nonlinear optical absorption and refraction coefficients are measured by using the top-hat Z-scan technique at a wavelength of 532 nm with 35 ps duration pulses. Reactive orange 1 has the two-photon absorption coefficient of 1.20 cm/GW and the nonlinear refraction coefficient of -7.33 × 10-6 cm2/GW, respectively. In reactive orange 1, there occurs fast ground-state recovery by internal conversion likely via conical intersections. Low excited-state absorption and fast ground-state absorption recovery make it an ideal candidate for passive mode-locking of picosecond and femtosecond lasers as well as for fast nonlinear optical gating.
11
Paembonan, Solmin, and Hisma Abduh. "Penerapan Metode Silhouette Coefficient untuk Evaluasi Clustering Obat." PENA TEKNIK: Jurnal Ilmiah Ilmu-Ilmu Teknik 6, no. 2 (September 2, 2021): 48. http://dx.doi.org/10.51557/pt_jiit.v6i2.659.
Full textAbstract:
Dalam penelitian ini menggunakan metode k-means, metode ini dapat digunakan untuk menjadikan beberapa obat yang mirip menjadi suatu kelompok data tertentu. Salah satu cara untuk mengetahui tingkat kemiripan data adalah melalui perhitungan jarak antar data. Semakain kecil jarak antar data semakin tinggi tingkat kemiripan data tersebut dan sebaliknya semakin besar jarak antar data maka semakin rendah tingkat kemiripannya. Tujuan akhir clustering adalah untuk menentukan kelompok dalam sekumpulan data yang tidak berlabel, karena clustering merupakan suatu metode unsupervised dan tidak terdapat suatu kondisi awal untuk sejumlah cluster yang mungkin terbentuk dalam sekumpulan data, maka dibutuhkan suatu evaluasi hasil clustering. Berdasarkan evaluasi yang dilakukan terhadap hasil clustering dengan nilai dari silhouette coeficient = 0,4854. In this study using the k-means method, this method can be used to make several similar drugs into a certain data group. One way to determine the level of similarity of the data is through the calculation of the distance between the data. The smaller the distance between the data, the higher the level of similarity between the data and vice versa, the greater the distance between the data, the lower the similarity level. For a number of clusters that may be formed in a data set, an evaluation of the results of clustering is needed. Based on the evaluation carried out on the results of clustering with the value of the silhouette coefficient = 0.4854.
12
Ciobotaru, Ioana Alina, Danut Ionel Vaireanu, Irina Elena Ciobotaru, and Oana Claudia Ciobotea Barb. "The Influence of the Curing Temperature on the Properties of Some Silane Films." Revista de Chimie 68, no. 7 (August 15, 2017): 1413–18. http://dx.doi.org/10.37358/rc.17.7.5686.
Full textAbstract:
This paper discusses the importance of the temperature drying process on some silane films in order to obtain a coating with specific properties (stability in time, resistance to corrosion attack and compactness) that would make them appropriate to be used as anticorrosive protection layers. Electrochemical techniques such as open circuit potential and electrochemical impedance spectroscopy were employed in order to characterize the investigated deposited silane films on aluminium substrate. The validation of the experimental electrochemical impedance spectroscopy data was carried out using the comparison of the validation coefficient versus the Pearson coefficient computed for a a=0.05.
13
Li, Kun, and Ling Yu. "Study on Global Stability of Mono-Overhanging Steel Beam." Advanced Materials Research 186 (January 2011): 151–55. http://dx.doi.org/10.4028/www.scientific.net/amr.186.151.
Full textAbstract:
The primary objective of this paper is to put forward a recommended equivalent calculated length coefficient for global stability analysis of the mono-overhanging steel beam applied widely in the steel building construction. The formulas of the total potential energy of the mono-overhanging beam are deduced firstly. Then the formula of the critical moment of the global stability of the mono-overhanging beam is obtained. By introducing the equivalent calculated length coefficient of the global stability and finding out the major factors which affected it, the formula of the coefficient is deduced. This formula includes two kinds of load acted on different position and it can make the global stability analysis of the mono-overhanging steel beam more convenient.
14
Laukaitis, Antanas, and Vytautas Lasauskas. "AKYTOJO BETONO GARSO ABSORBCIJOS TYRIMAI/POROUS CONCRETE SOUND ABSORPTION INVESTIGATION." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 2, no. 8 (December 31, 1996): 67–72. http://dx.doi.org/10.3846/13921525.1996.10590174.
Full textAbstract:
Low-density porous concrete can be used as a sound absorbing material. This paper generalizes porous concrete sound absorption investigations. Porous concrete relative wave resistance modulus is longer than air wave resistance W=1 and that is why this material can be ascribed to materials with a high resistance to air flows, i.e. materials with a satisfactory sound absorption. Various thickness porous concrete sample sound absorption coefficients can be calculated according to equations (1), (2), (3), when wave parameter values are determinated (Table 1). Normal sound absorption coefficient measurement results (Fig. 1) show that for 35 mm and thicker samples the coefficient does not vary. It means that the samples apparent resistance (impleance) coincides with the materials wave resistance. The sound absorption coefficient increases (Fig. 2) with a decrease in porous concrete density. The asymmetric average dependency is expressed by a rectilinear curve (Fig. 3). The sound absorption coefficient depends not only on porous concrete density, but also on its nature (Fig. 4). The different sound absorption coefficient values for uniform density porous concrete can be explained by the various structure of porous concrete products, i.e. a change in pore dimensions, their amount and distribution (Fig. 5, Table 2). The production of acoustical slabs has shown that 280350 kg/m3 density porous concrete products are not sufficiently strong. It was therefore decided to increase their density to 460 kg/m3, with the purpose of increasing the sound absorption coefficient by using various special form resonators (cavity-type accelerators). The influence of the cuts on sound absorption is given in Fig. 6 (cut step is 22 mm). Measurements in a reverberation chamber have shown that the sound absorption coefficient value in porous concrete slabs with deeper or complex cuts increases, but it is harder to produce slabs with complex form cuts. It is easier to make a simple form resonator. Reverberated sound absorption for regular form resonators is given in Fig. 7. Porous concrete slab surface acoustical resistance decreases due to cuts and that is why there is an increase in sound absorption coefficients (Fig. 7, 2 and 3 curves).Porous concrete slabs with resonator cuts on both sides can be used in spacious constructions, for noise absorption in industrial premises. In this case, the construction sound absorption coefficient depends on the lay-out of these slabs. Three types of special lay-outs were investigated (Fig. 8, Table 3). Most of the investigated constructions have revertible sound absorption coefficients higher than 1. This is explained by sound diffraction phenomena on the slab edges. The most effective of all the investigated constructions are those where porous concrete slabs with two-sided perforations are hung jointly (Fig. 8, curves 6 and 10). They are effective in the entire distance between the slabs. The reverberation absorption coefficient decreases for all types of constructions (Fig. 8, curves 1 and 2, 5 and 6, 7–10). The special construction sound absorption coefficient can be changed by selecting porous concrete slab lay-out.
15
Сидоров, А. В., В. М. Грабов, А. А. Зайцев, and Д. В. Кузнецов. "Термоэлектрические и термоэлектрокинетические явления в коллоидных растворах." Физика и техника полупроводников 53, no. 6 (2019): 765. http://dx.doi.org/10.21883/ftp.2019.06.47724.33.
Full textAbstract:
On the basis of mathematical modeling and exper-iment the analysis of thermoelectric and thermoelectrokineticphenomena in colloidal solutions is carried out. It is shownthatcolloidal particles make a significant contribution to thevalue ofthermoelectric and thermoelectrokinetic emf and in most casesdetermine the sign of the thermoelectric emf coefficient, primarilydue to the high values of the heat transfer of colloidal particlescompared to ions.
16
Yang, Qianqian, Xiaolei Wang, Kaihua Yang, Jinxiang Deng, Ruijuan Nie, Qingsong Deng, Xuegang Chen, Hongwei Yang, Kailin Xu, and Furen Wang. "The Positive Temperature Coefficient of Resistivity in BiFeO3 Films." Nanomaterials 12, no. 6 (March 8, 2022): 892. http://dx.doi.org/10.3390/nano12060892.
Full textAbstract:
The use of lead-free ceramic film materials with positive temperature coefficient of resistivity (PTCR) is widespread in temperature heaters and sensors in micro-electromechanical systems. In this research, the out of plane transport properties of the BiFeO3 (BFO) films have been studied. Surprisingly, PTCR was found in the BFO ceramic films due to the strongly correlated interaction between the multiferroic material BFO and the superconductor YBCO perovskite oxides. To our knowledge, this is the first report on the PTCR effect of BFO films. The BFO/YBCO interface and the bulk conductivity of BFO are important for the PTCR effect, as they make it possible to compare the transport properties of Au/BFO/YBCO- and YBCO/BFO/YBCO-type structures. PTCR was observed in Au/BFO/YBCO at a bias voltage of more than 2 V, but not in the YBCO/BFO/YBCO, even with a 40 V bias voltage. PTCR was found after BFO breakdown of a YBCO/BFO/YBCO capacitor. This indicated that the conductivity of BFO is critical for PTCR. The dependence of PTCR on the superconducting transition temperature illustrates that a cooper-pair can be injected into BFO. Our work presents a method by which to produce a lead-free ceramic film material with PTCR.
17
Babenko, S., and A. Bad'in. "On the Dose Coefficient of Uranium Hexafluoride." Medical Radiology and radiation safety 66, no. 5 (November 2, 2021): 11–17. http://dx.doi.org/10.12737/1024-6177-2021-66-5-11-17.
Full textAbstract:
Introduction: Uranium hexafluoride (UF6, UHF) is a gaseous product containing uranium and fluorine. Once in the air, it interacts with water vapor and produces hydrolysis products that can penetrate the human body and lead to the chemical effects of uranium and fluorine, as well as the radiation effects of uranium on the body. This action can be very strong and therefore serious attention has been paid to its study for a long time.
Purpose: Quantitative calculation of the radiation effects of uranium on humans and their analysis in the conditions of daily work at nuclear power plants, as well as in emergency situations.
Material and methods: We consider uranium hexafluoride that appears under certain conditions in the air of the working rooms of some enterprises and describes methods for describing the distribution of UHF hydrolysis products to objects that can sense their effects. All these methods are combined into a single integrated model. The analytical expressions obtained in the framework of this model at various stages are given, which make it possible to calculate the radiation effect of UHF.
Results: The calculated values of the characteristics of the radiation exposure are given, their analysis is carried out. The conditions are formulated under which there is a danger of serious radiation exposure of uranium hexafluoride to employees of nuclear power plants during everyday work and in emergency situations.
Conclusion: Based on all the material presented, it is concluded that the constructed mathematical model reliably describes the event in question and allows us to calculate the radiation effect of uranium on humans.
18
Chen, Chaoyu, Junli Chen, Fengxin Sun, Huijuan Yang, Zhijun Lv, Qihong Zhou, Zhaoqun Du, and Weidong Yu. "Study of the vibration transmission property of warp-knitted spacer fabrics under forced sinusoidal excitation vibration." Textile Research Journal 88, no. 8 (February 7, 2017): 922–31. http://dx.doi.org/10.1177/0040517517690630.
Full textAbstract:
The main content dealt with in this paper was to make a theoretical analysis of the vibration transmission property of spacer fabric as cushion materials. A forced vibration test with sinusoidal excitation was conducted, and the corresponding model of the vibration transmission coefficient was established based on a single-degree-of-freedom system. Experimental and theoretical vibration indexes, including natural frequency and the vibration transmission coefficient, were obtained from experimental and theoretical vibration transmission coefficient–frequency curves, respectively. After comparing theoretical parameters with experimental parameters, we were pleased to find out that their maximum vibration transmission coefficient and natural frequency showed good accordance with each other. Moreover, the effect of different parameters of spacer fabric on vibration transmission properties, including thickness, filament diameter, area density and inclination angle and arrangement of spacer filaments, were investigated, which is helpful to better design spacer fabrics with good vibration transmission.
19
Ma, Jun. "The Unsteady Dynamic Analysis of Football during Rotation." Applied Mechanics and Materials 246-247 (December 2012): 514–18. http://dx.doi.org/10.4028/www.scientific.net/amm.246-247.514.
Full textAbstract:
This paper uses infrared high-speed camera the QUALISYS-MCU500 infrared monitoring of long-range system, when football players kicked out football, we make the soccer unsteady dynamic analysis of nonlinear algebraic modeling, the modeling accuracy, the adjustment factor number, and then give the coefficient matrix, and finally calculate the law of motion, according to the modeling results, we calculate the curve giving the football spins.
20
Gilmutdinov, Ruslan V., Igor I. Krasnolobov, Nikolay L. Menshikh, and Sergey A. Fedorov. "Methodical errors in measuring the specular reflection coefficient from a planar sample of material for two types of measuring facilities." Izmeritel`naya Tekhnika, no. 6 (2021): 44–50. http://dx.doi.org/10.32446/0368-1025it.2021-6-44-50.
Full textAbstract:
This paper is discussed two methods for measuring the bistatic scattering characteristics of flat samples of the material. The experimental studies and numerical simulations of the dependence of the specular reflection coefficient on the incident angle of wave on a flat material sample carried out in the bistatic scheme of the experiment (rotation of the receiving and transmitting antennas) and in the monostatic scheme using a dihedral corner reflector (rotation of the object). Measurements for the magnetodielectric flat sample were carried out in ITAE RAS on two test facilities with the corresponding scheme of the experiment. To identify the errors of the methods used, we carried out numerical simulations of the measurement of the specular reflection coefficient of the sample under test by the method of integral equations (method of moments) in the FEKO program in the formulation of two experimental schemes. The obtained results were compared with each other and with the results of analytical calculations of the specular reflection coefficient carried out using the Fresnel formulas when considering an infinite flat layer of material. These calculations make it possible to compare the methodical errors in measuring the reflection coefficient in the two considered experimental schemes. It was shown that the results of the measurements using the corner reflector give methodical errors (deviations from the analytical calculation) by 1–2 dB more than the measurements on the bistatic facility. The results of experiments and numerical simulations are in agreement with each other. The conclusions obtained in this work are applicable to any experimental facilities for the study of planar materials.
21
Skowron, Rajmund, and Tomasz Jaworski. "Changes in lake area as a consequence of plant overgrowth in the South Baltic Lakelands (Northern Poland)." Bulletin of Geography. Physical Geography Series 12, no. 1 (June 27, 2017): 19–30. http://dx.doi.org/10.1515/bgeo-2017-0002.
Full textAbstract:
AbstractThe authors carried out the analysis of changes in the plant overgrowth of the lakes based on cartographic materials. Among 6 793 lakes with the area exceeding 1 ha located in the lakelands of Northern Poland, 893 lakes were selected for the analysis. The lakes were selected on the grounds of the existing bathymetric plans and information on their overgrowth and depth relations. Over the last 50 years lake area declined by 1.9% (from 140 975.0 ha do 138 273.7 ha) and so did the lake area covered with emergent plants, i.e. by 0.27% (from 11 219.0 ha down to 10 637.2 ha). Emergent plants cover on average 7.69% of the lake area. In the case of the lakes of smaller areas (below 80 ha) or medium areas (80÷200 ha) the extent of plant overgrowth was 14.3 and 9.6% respectively. The article presents two indicators which determine plant overgrowth of the lakes. These are the coefficient of overgrowing the lakes (%) and the coefficient of overgrowing the shoreline (ha·km-1). These coefficients make it possible to study the extent of lake overgrowing in the South Baltic Lakeland, regardless the direction of these changes.
22
Abd-Elhamid, Hany F., Martina Zeleňáková, Zuzana Vranayová, and Ismail Fathy. "Evaluating the Impact of Urban Growth on the Design of Storm Water Drainage Systems." Water 12, no. 6 (May 31, 2020): 1572. http://dx.doi.org/10.3390/w12061572.
Full textAbstract:
Urban growth is one of the major causes of flooding in urban areas. This affects the runoff coefficients, which is among the most important factors that affect the design of storm water drainage systems. Changing the runoff coefficient will affect the design parameters of the drainage network, including outfall discharge, velocity, lag time and cost of construction. This study aims to assess the effect of changing the runoff coefficient due to urban growth on the design of a storm water drainage system. The hydrological models Hyfran, StormCAD and GIS are used to analyze different runoff coefficients. This study examines three zones in Dammam in the Kingdom of Saudi Arabia (KSA). The data developed from the models for the current case studies are used to develop an empirical equation to predict the max discharge for other catchments. The discharge is a function of the return period, runoff coefficient, drainage density, longest path, rainfall intensity and catchment area. To validate the developed equation, we use it to estimate the discharge in a real case study in South Korea. A comparison between the measured discharge and estimated discharge shows that the empirical equation is capable of predicting the maximum discharge for different catchments with high accuracy. Then, the validation of the models is carried out to determine the effect of the runoff coefficient on the design of a storm water drainage system in a case study in KSA. The results show that an increasing runoff coefficient due to urban growth increases the outfall discharge and velocity of storm water drainage systems, as well as affecting the cost of construction and decreasing the lag time. The cost increases by two to three times with increasing urbanization. This study provides a new perspective on the hydrologic impact of urban growth on the design of storm water drainage systems, which are essential for flood management. Moreover, the relationship between urban growth and the cost of storm drainage networks is explored, which could help decision makers to make appropriate judgements.
23
Wang, Xue Jin, Zhi Hong Zhang, and Zhong Hai Chen. "Dynamic Simulation and Analysis for Thermal Insulation and Heat Preservation of Wall." Applied Mechanics and Materials 361-363 (August 2013): 396–401. http://dx.doi.org/10.4028/www.scientific.net/amm.361-363.396.
Full textAbstract:
Aim at new energy-saving walls used in China buildings, based on thermal instantaneous response factors method, the author compiles programs to calculation and simulation, carries out air conditioning cooling load temperature, thermal response factors, periodic response factors and Z transfer function coefficient of new energy-saving walls in China buildings. On the basis of the data, the author gives the net work analysis about the effect of the heat preservation and insulation material, the heat preservation and insulation layer position and air blanketing thickness and how to make a difference to the heat preservation and insulation performance of walls, According to which, the strategy how to carry out energy saving in buildings under varying climate environmental conditions has been reached, which will pointed out for the designer how to make assort the heat preservation with the insulation in building, and the heat preservation with the insulation are in the service of energy saving in buildings.
24
Wang, Fa Hui, and Ying Liu. "Effect of Composition on the Tribological Behaviors of Ceramic-Matrix Friction Materials." Advanced Materials Research 1061-1062 (December 2014): 645–48. http://dx.doi.org/10.4028/www.scientific.net/amr.1061-1062.645.
Full textAbstract:
The steel fiber reinforced ceramic matrix friction material is prepared by nitrogen protection sintering method. The specimens of the three different friction materials containing different content of alumina, clay and potash feldspar are formulated. The friction and wear characteristics are determined by using the XD-MSM constant speed friction tester. The testing results show that the increase of potash feldspar and the decrease of clay content make friction coefficient become more stable and diminish the sensitivity of friction coefficient to the temperature changes. This study also identify that among the three friction materials investigated, the main wear mechanism converts from grain pull-out and fracture wear to adhesion wear and abrasive wear.
25
Rundo, Massimo, Paolo Casoli, and Antonio Lettini. "Experimental Methods for Measuring the Viscous Friction Coefficient in Hydraulic Spool Valves." Sustainability 13, no. 13 (June 25, 2021): 7174. http://dx.doi.org/10.3390/su13137174.
Full textAbstract:
In hydraulic components, nonlinearities are responsible for critical behaviors that make it difficult to realize a reliable mathematical model for numerical simulation. With particular reference to hydraulic spool valves, the viscous friction coefficient between the sliding and the fixed body is an unknown parameter that is normally set a posteriori in order to obtain a good agreement with the experimental data. In this paper, two different methodologies to characterize experimentally the viscous friction coefficient in a hydraulic component with spool are presented. The two approaches are significantly different and are both based on experimental tests; they were developed in two distinct laboratories in different periods of time and applied to the same flow compensator of a pump displacement control. One of the procedures was carried out at the Fluid Power Research Laboratory of the Politecnico di Torino, while the other approach was developed at the University of Parma. Both the proposed methods reached similar outcomes; moreover, neither method requires the installation of a spool displacement transducer that can significantly affect the results.
26
Fguiri, Ali, Naouel Daouas, M.-Sassi Radhouani, and Habib Ben Aissia. "Inverse analysis for the determination of heat transfer coefficient." Canadian Journal of Physics 91, no. 12 (December 2013): 1034–43. http://dx.doi.org/10.1139/cjp-2012-0520.
Full textAbstract:
The parallel hot wire technique is considered an effective and accurate means of experimental measurement of thermal conductivity. However, the assumptions of infinite medium and ideal infinitely thin and long heat source lead to some restrictions in the applicability of this technique. To make an effective experiment design, a numerical analysis should be carried out a priori, which requires a precise specification of the heating source strength and the heat transfer coefficient on the external surface. In this work, a more accurate physical and mathematical modeling of an experimental setup based on the parallel hot wire method is considered to estimate the two above-mentioned parameters from noisy temperature histories measured inside the material. Based on a sensitivity analysis, the heating source strength is estimated first using early time measurements. With such estimated value, determination of the heat transfer coefficient using temperatures measured at later times is then considered. The Levenberg–Marquardt (LM) method is successfully applied using a single experiment for the inverse solution of the two present parameter estimation problems. Estimates of this gradient-based deterministic method are validated with a stochastic method (Kalman filter). The effects of the measurement location, the heating duration, the measurement time step, and the LM parameter on the estimates and their associated confidence bounds are investigated. Used in the traditional fitting procedure of the parallel hot wire technique, the estimated heating source power provides a reasonable agreement between fitted and exact values of the thermal conductivity and the thermal diffusivity.
27
R. Jothilakshmi, G., P. Mohana Priya, and V. K. Suvithra. "Study of Hardware Implementation on Size of the Microcalcification Detection Using Embedded Systems." International Journal of Engineering & Technology 7, no. 3.27 (August 15, 2018): 415. http://dx.doi.org/10.14419/ijet.v7i3.27.17988.
Full textAbstract:
Detection of microcalcification in glandular breasts is highly critical for early stage cancer detection since, it is very small in size. To detect such smaller microcalcification a hardware device is needed, which is created by the using the digital mammography image from DDSM database the image of malignant breast is acquainted. Two levels of binning is carried out with respect to the RoI to calculate the range of reflection coefficient. Linear mapping of reflection coefficient with mass density is projected as 3D and simultaneously the size of respective second bin is calculated to derive the size if the microcalcification .This process is then implemented on hardware to make it more commercial for the people to detect the cancer at an early stage.
28
Shivashankar, Hiremath, Rajole Sangamesh, and S. M. Kulkarni. "Analysis of Coefficient of Thermal Expansion in Carbon Black Filled PDMS Composite." Materials Science Forum 978 (February 2020): 237–44. http://dx.doi.org/10.4028/www.scientific.net/msf.978.237.
Full textAbstract:
Polymer composites are gaining attention due to their superior thermal properties. Especially carbon black /carbon nanotubes/ graphene filled polymer composites are used in energy harvesting, thermal actuators and MEMS. The coefficient of thermal expansion (CTE) is one of the most important properties in the polymer composite. In the present study, thermal expansion of polydimethylsiloxane (PDMS) matrix is filled with carbon black particle of varied volume fraction is modeled. Two-dimensional finite element (FE) model is computed in order to explain the thermal expansion behavior of the polymer composite and same is carried out for ambient to 70 K temperature. A 2D regular arrangement of circular particle packing model is set up and simulated. The FE model predicts that filler geometry has a little effect on the thermal expansion than the percentage of filler in the composite. Thermal expansion of composite is compared with the theoretical model. It shows that the CTE of composite reduces as the filler percentage increase, also gives good agreement in the both models. Hence, it is found that the addition of carbon black to the polymer composite could make it perform significantly better in thermal expansion.
29
Han, Yi, and Jihong Chen. "Experimental investigation on tribological properties of UHMWPE with the addition of basalt fiber." Advanced Composites Letters 28 (January 1, 2019): 2633366X1989459. http://dx.doi.org/10.1177/2633366x19894596.
Full textAbstract:
To seek the effective and feasible way to enhance the tribological properties of ultrahigh-molecular-weight polyethylene (UHMWPE) materials, a comparative investigation on the tribological behavior of basalt fiber (BF) as filler in UHMWPE composites was carried out. BF/UHMWPE composites were investigated through friction and wear tests to evaluate its frictional and lubricate properties. The results showed that the friction coefficient of the UHMWPE composite decreased significantly under water sliding condition; under water and dry friction conditions, the friction coefficient decreases with the increase in load and rises as the rotational speed growing. When the BF/UHMWPE composites were tested under water-lubricated conditions, the material folding and pieces of debris were reduced obviously and the variation of wear depth was consistent with the results of friction coefficient. To evaluate the tribological properties of UHMWPE under various conditions, the research results make useful reference for UHMWPE manufacture and other relative experiments.
30
Lopez, Michael N., Nancy M. Quan, and Perla M. Carvajal. "A Psychometric Study of the Geriatric Depression Scale." European Journal of Psychological Assessment 26, no. 1 (January 2010): 55–60. http://dx.doi.org/10.1027/1015-5759/a000008.
Full textAbstract:
Criterion-referenced (Livingston’s r) and norm-referenced (Cronbach’s α and Gilmer-Feldt coefficient) techniques were used to calculate the internal consistency reliability of the 30-item Geriatric Depression Scale (GDS) on a sample (N = 417) of elderly medical outpatients. For the widely used cutoff score of 10 for depression, the criterion-referenced reliability (Livingston’s r) of the GDS total score was found to be .896, .883, and .891 for the elderly patients with Mini Mental State Examination (MMSE) scores > 17, ≤ 17, and total sample, respectively, while the norm-referenced reliability Gilmer-Feldt coefficient (and Cronbach’s α) of the GDS total score was found to be .895 (α = .893), .877 (α = .875), and .890 (α = .888), respectively. Tests of significance between the GDS total score means and reliability coefficients for the patients with MMSE scores > 17 and ≤ 17 were found to be nonsignificant. Therefore, the cognitive status of our sample does not seem to have an effect on the GDS total score. Item-total score correlations showed that 29 out of the 30 GDS items were good discriminators. The use of true score confidence intervals around GDS observed scores is recommended when used to make decisions about depression in the elderly.
31
Senthil Nayagam, V., Anamika, D. Gopinath, K. Vetri Velmurugan, Rani Fathima, Mary Joy Kinol, Prasath Alias Surendhar, and David Christopher. "Liquid Crystal Display (LCD) and Organic Light Emitting Diode (OLED) Applications on Natural Fibre Reinforced Polymer Matrix Composites." Advances in Materials Science and Engineering 2021 (November 26, 2021): 1–10. http://dx.doi.org/10.1155/2021/1934490.
Full textAbstract:
Natural materials are the alternative source for the manufacture of products due to environmental requirements. Hot injection moulding techniques make the composite product with fibreglass, granite waste filler, and polylactic acid (PLA). Five samples of each set and sampled with better hardness varied the volumetric percentage of glass fibre and the waste nanogranite particles. This effort is mainly concerned with evaluating the wear of dry sliding and friction of composites. Varying 15, 25, 35, and 45 N load, 750 and 1500 m sliding distance tested the composite materials, respectively. Parametric condition experiments were carried out at the stated process to record answers. Nanogranite composite materials are better than higher concentrations of glass fibre in PLA matrices composites, which are more resistant to wear and friction coefficients. The nanogranite powder is added with the filler element in the PLA matrix to provide a better coefficient of wear and rubbing. A high load of 45 N and a sliding distance of 1500 m were measured at low wear and low friction coefficients.
32
Chen, Zhong Chao, and Ji Min Zhang. "Fatigue Life Analysis of the Bolt." Applied Mechanics and Materials 121-126 (October 2011): 259–62. http://dx.doi.org/10.4028/www.scientific.net/amm.121-126.259.
Full textAbstract:
For the bolts on the experiment table, there are two main kinds of forces, namely, shear force and tensile force. This paper will test these two different forces that the bolts received, verifying their compliance with the service life. Finding out which situation is better by comparing the safety coefficient under the static load and the fatigue life under the fatigue load. And then put forward some reasonable measures for improving to make the bolts meet the fatigue life of the experiment platform.
33
Petacco, Nicola, Danilo Pitardi, Carlo Podenzana Bonvino, and Paola Gualeni. "Application of the IMO Second Generation Intact Stability Criteria to a Ballast-Free Containership." Journal of Marine Science and Engineering 9, no. 12 (December 11, 2021): 1416. http://dx.doi.org/10.3390/jmse9121416.
Full textAbstract:
A methodology is presented to systematically modify the hull shape of a ballast-free container ship, in order to manage the issue of righting lever variation in waves. The IMO second generation intact stability criteria have been identified as a stability performance assessment tool, while the vertical prismatic coefficient has been selected as the leading parameter of hull modifications to carry out the sensitivity analysis. A revised Lackenby procedure has been chosen to make systematic changes at the hull form. The outcomes of this investigation point out that the proposed procedure is suitable to enable the ship to be fully compliant with the IMO vulnerability levels with minor design adjustment.
34
Krupanek, K., A. Staszczyk, J. Sawicki, and P. Byczkowska. "The impact of nozzle configuration on the heat transfer coefficient." Archives of Materials Science and Engineering 1, no. 90 (March 1, 2018): 16–24. http://dx.doi.org/10.5604/01.3001.0012.0609.
Full textAbstract:
Purpose: The purpose of this paper is to elaborate guidelines regarding geometric configurations of a nozzle manifold that have an impact on the effectiveness of the quenching process and occurrence of quenching distortions. Design/methodology/approach: Within the framework of this study there an optimisation of nozzle manifold geometry was carried out with the help of numerical simulations created using Ansys CFX software. In the first stage, a simplification of the nozzle-sample system reduced to a two-dimensional simulation was employed to determine the most optimal location of the coolant stream. In the second stage, several arrangements of nozzle manifolds were tested in a three-dimensional simulation. The parameters that were taken into account included the rate of sample cooling, the uniformity of cooling with a sample volume and heat coefficient takeover read from its surface. Findings: The different active/inactive nozzle arrangements within the manifold and the impact of the specific arrangements on the uniformity of heat transfer from the sample surface were compared. Research limitations/implications: The simulations carried out within the framework of this study are one of the elaboration stages of a new flow heat treatment technology. Practical implications: The application of an efficient cooling chamber in flow treatment makes it possible to limit quenching distortions to a minimum. An optimal adjustment of cooling parameters and cooling nozzle configuration to the shape of the element in order to make the cooling uniform translate directly into a reduction in distortions. Avoiding the necessity to reduce distortions after quenching means there is a significant reduction in detail production costs (grinding). Originality/value: The concept of single-piece flow in the heat treatment for the mass industry is developing rapidly and constitutes a fully automated element of a manufacturing line, adjusted for the purposes of being included in the production process automatic control system. It also makes it possible to conduct comprehensive and integration quality supervision and management at the level of an individual element, which is not possible in the case of batch heat treatment, which is a gap in the production process.
35
Wang, Xing Rui, Ji Kai Jin, and Gang Yang. "Analysis on In-Plane and Out-Plane Instability Coupling of Steel Bowstring Arch Bridge with Box Section Single Rib." Advanced Materials Research 790 (September 2013): 337–40. http://dx.doi.org/10.4028/www.scientific.net/amr.790.337.
Full textAbstract:
Steel single rib box section arch bridge is established on the basis of secondary development using parametric language of large-scale finite element software ANSYS. On the premise of same sectional area A of arch rib,height breadth ratio h/b is changed, and both the spatial instability mode under the condition of arch bridges dead weight and the stability safety coefficient under the condition of the first step instability mode is calculated. With the aim to optimize distribution of stiffness and stability of single rib arch bridge, the target is to find out a height breadth ratio h/b which can make in-plane and out-plane instability mode coupling, that is to say, equivalent stiffness of in-plane and out-plane of the mode.
36
Su, Yan Chang, and Wen Xiang Wu. "Study on Characteristics and Oil Displacement Characteristics of High Concentration Polymer System." Advanced Materials Research 391-392 (December 2011): 255–59. http://dx.doi.org/10.4028/www.scientific.net/amr.391-392.255.
Full textAbstract:
Through laboratory experiments, viscosity stability of high concentration polymer solution was studied. Viscoelasticity of high concentration polymer was measured by HAAKE RS-150 Rheometer. The flow tests of high concentration polymer solution were carried out by utilizing artificial homogeneity cores, while the influence of injection time on displacement characteristics of high concentration polymer were studied on artificial heterogeneous cores. The results showed that high concentration polymer solution had a good stability within 15 days, but decreased significantly after 30 days. Both viscosity and elasticity of high concentration polymer are higher than the lower ones’. Because the high viscoelasticity of high concentration polymer made the flow resistance increase, resistance coefficient and residual resistance coefficient were very high. Therefore viscoelasticity of high concentration polymer could make a large improvement on chemical flooding recovery.
37
Zuev, N. D., A. S. Shunko, and N. V. Shunko. "RESEARCH OF THE REFLECTION COEFFICIENT OF WAVES FROM THROUGH-TYPE HYDRAULIC STRUCTURE WITH SUB-ВERTH SLOPE." Construction economic and environmental management 80, no. 3 (2022): 139–49. http://dx.doi.org/10.37279/2519-4453-2021-3-139-149.
Full textAbstract:
Тhe paper presents the results of experimental studies carried out on the basis of physical modeling using the latest measuring equipment and laboratory equipment from Wallingford (Great Britain). Loads from the force effect of wind waves are decisive when choosing the types and design features of offshore structures designed taking into account the natural and climatic conditions of each specific construction area. For this reason, the lack of accurate methods for calculating wave loads on offshore hydraulic structures does not allow ensuring their reliability during design and operation. The purpose of the presented experimental studies is to clarify and make additions to the section SP 38.13330.2018 [1] «Wave elements in a fenced water area», dedicated to determining the values of the wave reflection coefficient for structures of through hydraulic structures, when exposed to the calculated wind waves. This topic in the regulatory document [1] is not considered broadly and extensively enough. But, at the same time, having information about the exact values of the reflection coefficient of waves, it is possible to reasonably lower the elevation of hydraulic structures and carry out a number of constructive measures, which ultimately lead to a reduction in the cost of construction with a simultaneous increase in its quality.
38
Banerjee, Arindam. "An Empirical Risk and Return Analysis of Select Stocks in NASDAQ 100." Accounting and Finance Research 11, no. 2 (March 13, 2022): 1. http://dx.doi.org/10.5430/afr.v11n2p1.
Full textAbstract:
Stock market indices are considered to be a powerful economic indicator. These indices can be classified based on the methodology of weight allocation for each stock and the rules governing the entry, retention and exit criteria of various stocks in the index. This paper presents a descriptive and an exploratory analysis carried out on the daily returns data of NASDAQ 100 (^NDX) index and shortlist of 20 stocks in the index. Random sampling was conducted at the sector level strata of all stocks that make up the index. This approach was followed to avoid selection bias and that stocks from the varied sectors are represented equally for this analysis. R-squared values and correlation coefficients were used to determine the explain-ability and relationship between the stock returns and the index returns respectively. The paper applied descriptive univariate analysis on daily returns at an individual stock level and at an aggregated sector level. Inter-relationship between stocks and the index returns was carried out by computing Pearson’s correlation coefficient across the different combinations of stocks and index return values. Linear regression was carried out identify the explain ability of the variance in the returns of from the index to the returns from the stocks. All analysis was carried out using the python and the stats-models library. As anticipated, the returns of randomly picked 20 stocks were able to explain ~85 % of the variance of the returns of index. One of the primary focus of the paper was to explore whether NASDAQ-100 index can explain the variability of the technology stocks relatively more than the stocks that belong to other sectors in its portfolio owing to the nature of most stocks that make up the index.
39
Kazansky, Yury, and Yanis Slekenichs. "Power coefficient of reactivity: definition, interconnection with other coefficients of reactivity, evaluation of results of transients in power nuclear reactors." Nuclear Energy and Technology 4, no. 2 (November 26, 2018): 111–18. http://dx.doi.org/10.3897/nucet.4.30663.
Full textAbstract:
It is assumed by the authors of the present paper that with growing contribution of nuclear power in the production of electricity, nuclear power plants will be used to a higher degree in a manoeuvrable mode of operation rather than in the base-load mode. In other words, change of power from the nominal level to that of coverage of auxiliary loads will be becoming quite common and not so rare event as scheduled reactor shutdowns for fuel reloading or preventive works. There exist well-known problems in the use of nuclear reactors in the manoeuvrable operation mode, which include the task shared by all types of nuclear reactors. It is advisable to have a unified indicator weakly power-dependent and fairly easy to measure, which would make it possible to formulate the judgement about the nature of the transient processes within the entire power range and to assess the reactivity required for changing the power level by the preset value. Power reactivity coefficient (PRC) can be used as such indicator. Analysis was made of existing definitions and understanding of PRC in relevant references. It turned out that there is no generally accepted definition of the PRC. Based on the performed study, the following definition was suggested: the PRC is the ratio of the low reactivity introduced into the reactor to the power increment at the end of the transient process. It is assumed here that variation of reactivity is dependent on the energy released in nuclear fission but is not related to the changes of reactivity induced by feedback signals in the automatic reactor power control system. Analysis of the relationship between the PRC and temperature coefficients and technological parameters associated with the steady-state control program was performed taking the above suggested definition into account. PRC calculations were performed using the simplest model of VVER-1000 type power reactor. It was found that PRC is weakly power-dependent. The purpose of the present study is to investigate dependence of PRC on the temperature reactivity effects and on the technological parameters associated with the steady-state control program of the power unit, using the example of VVER-1000. Effects of PRC on the static and dynamic power reactor operation modes are analyzed.
40
Li, Qin, and Kit Newton. "Diffusion Equation-Assisted Markov Chain Monte Carlo Methods for the Inverse Radiative Transfer Equation." Entropy 21, no. 3 (March 18, 2019): 291. http://dx.doi.org/10.3390/e21030291.
Full textAbstract:
Optical tomography is the process of reconstructing the optical properties of biological tissue using measurements of incoming and outgoing light intensity at the tissue boundary. Mathematically, light propagation is modeled by the radiative transfer equation (RTE), and optical tomography amounts to reconstructing the scattering coefficient in the RTE using the boundary measurements. In the strong scattering regime, the RTE is asymptotically equivalent to the diffusion equation (DE), and the inverse problem becomes reconstructing the diffusion coefficient using Dirichlet and Neumann data on the boundary. We study this problem in the Bayesian framework, meaning that we examine the posterior distribution of the scattering coefficient after the measurements have been taken. However, sampling from this distribution is computationally expensive, since to evaluate each Markov Chain Monte Carlo (MCMC) sample, one needs to run the RTE solvers multiple times. We therefore propose the DE-assisted two-level MCMC technique, in which bad samples are filtered out using DE solvers that are significantly cheaper than RTE solvers. This allows us to make sampling from the RTE posterior distribution computationally feasible.
41
Biernacki, Krzysztof. "Selection of the optimum tooth profile for plastic cycloidal gears." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 228, no. 18 (April 14, 2014): 3395–404. http://dx.doi.org/10.1177/0954406214531408.
Full textAbstract:
Cycloidal gears make up the main working unit of hydraulic gerotor machines. In the article, a question of a more efficient application of plastics in building the gears is discussed. The discussion is based on a numerical strain analysis which was done by means of the finite elements method. The stress and deformation values in the operating cycloidal gears were specified. The numerical analysis was carried out in two stages in order to determine the optimum gear tooth profile. The profile depends on the tooth height and on the tooth correction coefficient. At the first stage, the optimum tooth height coefficient λ was calculated. Having determined the optimum value λ, the analysis was continued, and at the second stage, the optimum correction coefficient v for the gears at an earlier selected constant value λ was defined. The analysis results were useful in selecting parameters for determining the geometrical characteristics of the cycloidal gears. The parameters were then used in defining the most suitable tooth profile for the hydraulic machine featuring the cycloidal gears.
42
Greslou, L., and Y. Mahe. "STUDY OF THE REFLECTION COEFFICIENT OF A WAVE ON AN INCLINED PLANE." Coastal Engineering Proceedings 1, no. 5 (January 29, 2011): 7. http://dx.doi.org/10.9753/icce.v5.7.
Full textAbstract:
This paper is intended to make a further contribution, based on laboratory experiments, to the many tests carried out to date on the problems of the reflecting capacity of an obstacle attacked by waves.
Systematic measurements made in a wave flume at the Laboratoire Dauphinois d'Hydraulique, with obstacles formed by plane surfaces inclined between 0 and 90 degrees, have made it possible to plot a graph showing the variation of the reflection coefficient for a wave approaching these obstacles in a normal direction, in relation to the slope of the latter and the shape of the wave.
It has also been possible to ascertain the effect of the wall roughness, because some tests were made with rock-filled breakwaters.
A comparison has been made between the experimental curves obtained in this way and Miche's theoretical curves. This has shown that the latter appear satisfactory, and it has made it possible to investigate some points with Miche himself thought should be clarified by tests in a laboratory.
A graph of this kind can be of great value for estimating the reinforcement of disturbance near sea structures. This disturbance often makes navigation and berthing difficult. But the full understanding of these curves can lead to the knowledge of whether a talus or a beach has a sufficiently gentle slope to efficiently protect a coastline by distributing the energy of waves before they reach the area which must be protected.
43
Li, Tao, Yuan Fang Du, She Liang Wang, and Tao Yang. "Ductility and Strength of Modified Recycled Aggregates Columns with Silica Fume and Hybrid Fiber." Applied Mechanics and Materials 446-447 (November 2013): 1558–65. http://dx.doi.org/10.4028/www.scientific.net/amm.446-447.1558.
Full textAbstract:
In order to make up for the defects of new and old aggregate, making full use of the function of silicon fume and hybrid fiber, cyclic loading tests were carried out on five concrete with recycled aggregate columns and an ordinary concrete frame column under the combined influence with different admixtures and its ratios (silica powder and hybrid fiber) . This text was focused on the properties and failure pattern of specimens, displacement ductility coefficient, ultimate displacement rotation and horizontal bearing capacity. The test results showed that a low content of silica powder could improve ductility performance, while the addition of hybrid fiber made the ductility to be further enhanced and improved the early strength by a larger margin than later stage. With the constitutive relation and adjusting the modification coefficient of concrete stress strain curve using MATLAB, It could be more accurate on the bearing capacity of the columns.
44
Yekta, Ahmad, Zahra Masoumi, and Mitchell A. Winnik. "Luminescence measurements of oxygen permeation and oxygen diffusion in thin polymer films." Canadian Journal of Chemistry 73, no. 11 (November 1, 1995): 2021–29. http://dx.doi.org/10.1139/v95-250.
Full textAbstract:
A new method is developed for analyzing the diffusion of oxygen in thin polymer films via fluorescence quenching measurements. We begin by reviewing previous methods, all of which involve approximations, for the measurement of permeability and diffusion coefficient by luminescence quenching; their shortcomings are clarified. An exact analytic theory is developed that successfully couples Fick's laws of diffusion to the Stern–Volmer equation of intensity quenching. Various modes of experimentation with polymeric films are considered. The equations we derive make the unexpected prediction that the rate of emission intensity decay when O2 diffuses into a polymer film is much faster than the rate of emission intensity enhancement when O2 diffuses out of the same film, even when the molecular diffusivity remains unchanged. Experiments show that this is indeed the observed behaviour. Keywords: diffusion coefficient, oxygen permeability, polymers, quenching, luminescence quenching, Fick's laws. Stern–Volmer equation.
45
Tran, Ngoc Khanh, Van Quang Dao, Phu Khanh Nguyen, Thi Kim Dung Hoang, and Van Khang Nguyen. "Numerical Investigations of Aerodynamics Characteristics of Main Rotors in Helicopter UAV Used for Pesticide Spraying in Agriculture." Applied Mechanics and Materials 889 (March 2019): 425–33. http://dx.doi.org/10.4028/www.scientific.net/amm.889.425.
Full textAbstract:
In the last several decades past, Helicopters UAVs (Unmanned Aerial Vehicles) have quickly developed and day by day, they play an important role in human life. As it is well-known, helicopters UAV make some outstanding characteristics such as light weight, flexibility and particularly automatically controlled. By applying these characteristics, we research and manufacture Helicopter UAV using for spraying pesticide in agriculture. One of the most important components is main rotor because main rotor generated thrust, drag and momentum. Helicopters UAV efficient changed depending on main rotor. The research works focus on aerodynamics characterization of main rotor in helicopter UAV. This work uses CFD tool in ANSYS CFX software to calculate the aerodynamics parameters generated by main rotor using in UAV. The aim is to characterize the aerodynamics characteristics such as thrust, drag, pressure, aerodynamics quality on the different flight modes (hover, vertical and forward flight). Firstly, the simulations are carried out in hover flight mode with different blade pitch angles. The results are compared to experiment date in another research to validate numerical results. Then, the simulations are carried out in vertical flight mode and forward flight mode. The results showed that thrust and drag coefficient creased with increasing blade pitch angle. When blade pitch angle started from 1800, thrust coefficient decreased but drag coefficient increased sharply. The rotor performance was measured by aerodynamics quality and numerical results showed that the best rotor performance was at 900. In the vertical flight mode, the thrust and drag coefficient decreased with increasing vertical velocity but rotor performance increased slightly. The best vertical velocity for vertical flight is around 2 m/s and 3 m/s. Finally, in forward flight mode, the aerodynamics characterizations of rotors depended on azimuthal angular position of blade or time. Our helicopter operates in environment with light gust. The results showed the change of aerodynamics coefficient to time. Both thrust and drag coefficient changed but the rotor performance did not change much.
46
Putra, Dhani Dharmala, Suselo Utoyo, and Sumardi Sumardi. "STUDI KELAYAKAN TEKNIK DAN FINANSIAL PERUMAHAN VILLA BUMI BATARA PONOROGO." Jurnal JOS-MRK 2, no. 3 (September 20, 2021): 110–14. http://dx.doi.org/10.55404/jos-mrk.2021.02.03.110-114.
Full textAbstract:
The purpose of this study is to conduct a research on the feasibility study aimed to find out whether the construction is feasible or not feasible to be built on the Bumi Batara Villa Housing development project in Ponorogo. In marketing market analysis by distributing questionnaires. Technical analysis uses the Building Base Coefficient (KDB), the Building Floor Coefficient (KLB), and the Green Base Coefficient (KDH). While those used in financial analysis are Net Present Value (NPV), Benefit Cost Ratio (BCR), Internal Rate of Return (IRR), and Payback Period (PP) that are used as parameters with home sales are considered 100% during the investment plan year to 4. Land optimization of house type and land is effective by using the simplex method, for financial feasibility declared feasible by getting a profit. With revenues earned over 4 years with 76 units sold in the amount of Rp.41,813,360,829.57 and expenses in the amount of Rp.38,218,442,595.37. Then do the land optimization to make maximum use of the existing land of 10,157 m2 with a community interest of 124 units and a maximum profit of Rp.9,030,171,549.18 was obtained.
47
O’Meara, John, and Ashwin Vaidya. "A Network Theory Approach to Curriculum Design." Entropy 23, no. 10 (October 15, 2021): 1346. http://dx.doi.org/10.3390/e23101346.
Full textAbstract:
In this paper we hypothesize that education, especially at the scale of curriculum, should be treated as a complex system composed of different ideas and concepts which are inherently connected. Therefore, the task of a good teacher lies in elucidating these connections and helping students make their own connections. Such a pedagogy allows students to personalize learning and strive to be ‘creative’ and make meaning out of old ideas. The novel contribution of this work lies in the mathematical approach we undertake to verify our hypothesis. We take the example of a precalculus course curriculum to make our case. We treat textbooks as exemplars of a specific pedagogy and map several texts into networks of isolated (nodes) and interconnected concepts (edges) thereby permitting computations of metrics which have much relevance to the education theorists, teachers and all others involved in the field of education. We contend that network metrics such as average path length, clustering coefficient and degree distribution provide valuable insights to teachers and students about the kind of pedagogy which encourages good teaching and learning.
48
Pranoto, Aji, Septa W, Yudha Orienta, and Wisnu Y. Santika. "REDESAIN BODY MOBIL MATARAM PROTO V5 DENGAN MEMPERTIMBANGKAN ASPEK AERODINAMIS." Jurnal Pendidikan Vokasi Otomotif 3, no. 2 (May 1, 2021): 73–80. http://dx.doi.org/10.21831/jpvo.v3i2.40694.
Full textAbstract:
The Energy Saving Car Contest (KMHE) is a contest organized by the Ministry of Research, Technology and Higher Education (Kemenristekdikti). This is a contest among students to make a national level fuel efficient vehicle. The purpose of designing this design is to produce an energy-efficient car body design "Mataram Proto" and to produce a vehicle that has a good aerodynamic level. This design of the car body is designed elegantly but still has good aerodynamics and does not reduce the safety aspects of the driver. The process of making a car body design uses Autodesk Inventor and the process of aerodynamic analysis of the Mataram Proto car body uses Ansys Mechanical software. Aerodynamic testing was carried out at an air speed of 45 km / h or 12.5 m / s. From the previous Mataram Proto body test results, the drag coefficient was 0.233 and the lift coefficient was 0.1887 and from the Mataram Proto V5 car body test, the drag coefficient was 0.47 and the lift coefficient was 9.95. From the results of this test, it shows that the previous Mataram Proto car body had a better aerodynamic level due to the difference in the input of different airspeed variables, where the air velocity on the previous Mataram Proto car body was 40 (km / h) and the air speed on the Mataram Proto V5 body. amounting to 45 (km / hour).
49
BRAGHIN, FÁBIO L. "ISOVECTOR AND SPIN-ISOVECTOR SYMMETRY ENERGIES FROM POLARIZABILITIES." International Journal of Modern Physics E 19, no. 08n09 (September 2010): 1585–91. http://dx.doi.org/10.1142/s0218301310015990.
Full textAbstract:
The momentum dependence of the nuclear matter isovector symmetry energy coefficient [Formula: see text] is presented in the framework of the nuclear matter polarizability with Skyrme interactions, as worked out in Refs. 1, 2. A slightly more complete account is presented for the spin-isovector symmetry energy [Formula: see text] as function of the temperature and momentum exchange and it is found to have a quite similar behavior to the isovector one [Formula: see text]. The variation of [Formula: see text] with temperature is quite soft and decreasing whereas the dependence on exchanged momentum can make [Formula: see text] to be close to zero, although it does not reach negative values.
50
Hannan Glendoh, Sentot. "INFLUENTIAL FACTORS TO THE WORK PRODUCTIVITY OF THE WIRARAJA UNIVERSITY IN SUMENEP - MADURA." EKUITAS (Jurnal Ekonomi dan Keuangan) 6, no. 1 (December 8, 2016): 69. http://dx.doi.org/10.24034/j25485024.y2002.v6.i1.1946.
Full textAbstract:
This research (1999) entitled "The Influential Factors Toward the Work Force Productivity of The Wiraraja University In Sumenep - Madura", is driven by the heart call as an Indonesian citizen to participate in effort to make the nation 's life cleverer and to increase Indonesian people quality in realizing a developed , just and prosperous society based on Pancasila (The State Ideology) and 1945 Constitution. It is realized that to increase work productivity, human resource factor in developing a University is very important, especially lecturers who are in reality always have direct contact with the student in the learning - teaching process. So, the research to know work productivity in University is very important to carry out. The chosen population for this research in the employees of The Wiraraja University In Sumenep which is located in the eastern tip of the Madura island, with total employees 74, and those whom are used for samples are 54i.e. those who don't occupy a position as the Rector, Assistant Rector, Dean, and Assistant Dean. This research is carried out LO test the hyphotesis by processing data through analysis of data of dependent variable (work productivity) and independent variables (motivation, discipline, work climate, and accupational opportunity). After we have discussed, finally we draw a conclusionThe first hyphotesis test, about influence of independent variable which contains motivation, discipline, work climate, and accupational apportunity variables toward independent variable (work productivity variable) is retained. Work productivity amount to 58%, and the rest amount to -12 % is influenced by other independent variables whict are not included in this research.The most dominant variable from those four independent variable namely motivation, discipline, work climate, and occupational opportunity variable, is the motivation variable (regression coefficient = 0.3488) subsequently by work climate variable (regression coefficient = 0.224 1), discipline variable (regression coefficient= 0.1621), and occupational opportunity variable (regression coefficient = 0.1183).