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1
Shugurova, Marina A., Andrey V. Tsyganov, and Yulia V. Tsyganova. "Analysis of methods for modeling human daily thermometry data." Zhurnal Srednevolzhskogo Matematicheskogo Obshchestva 24, no. 4 (December 31, 2022): 469–84. http://dx.doi.org/10.15507/2079-6900.24.202204.469-484.
Повний текст джерелаАнотація:
Abstract. Mathematical and computer modeling of daily thermometry allows to study processes of human thermal homeostasis more deeply. In practice, thermometry data is obtained using a digital thermometer, which autonomously reads the temperature of human skin in certain time intervals. The aim of present work is to analyse the methods of modeling and processing of human daily thermometry data. The first method consists in applying linear discrete stochastic models in the state space with Gaussian noises and known vector of input actions, while the estimation of the state vector is performed by discrete covariance Kalman filter. The second method assumes that the vector of input actions is unknown, and the S. Gillijns and B.D. Moor algorithm is used to process daily thermometry data. An alternative option is to use a model with an extended state vector and a Kalman filtering algorithm. The third method takes into account the presence of anomalous measurements (outliers) in the measurement data, and correntropy filter is proposed for their effective filtering. Numerical experiments for modeling and processing of daily thermometry data in MATLAB were carried out in order to compare the quality of discrete filtering algorithms. Modeling of thermometry data was carried out using a three-dimensional model 3dDRCM (3-dimension Discrete-time Real-valued Canonical Model). The results obtained can be used in the study of human daily thermometry processes, for example, to study the reaction of the athlete’s body to the received load.
2
Zhu, Zhongfan, and Jingshan Yu. "Estimating the Bed-Load Layer Thickness in Open Channels by Tsallis Entropy." Entropy 21, no. 2 (January 29, 2019): 123. http://dx.doi.org/10.3390/e21020123.
Повний текст джерелаАнотація:
In the research field of river dynamics, the thickness of bed-load is an important parameter in determining sediment discharge in open channels. Some studies have estimated the bed-load thickness from theoretical and/or experimental perspectives. This study attempts to propose the mathematical formula for the bed-load thickness by using the Tsallis entropy theory. Assuming the bed-load thickness is a random variable and using the method for the maximization of the entropy function, the present study derives an explicit expression for the thickness of the bed-load layer as a function with non-dimensional shear stress, by adopting a hypothesis regarding the cumulative distribution function of the bed-load thickness. This expression is verified against six experimental datasets and are also compared with existing deterministic models and the Shannon entropy-based expression. It has been found that there is good agreement between the derived expression and the experimental data, and the derived expression has a better fitting accuracy than some existing deterministic models. It has been also found that the derived Tsallis entropy-based expression has a comparable prediction ability for experimental data to the Shannon entropy-based expression. Finally, the impacts of the mass density of the particle and particle diameter on the bed-load thickness in open channels are also discussed based on this derived expression.
3
Suslin, V. P., and M. G. Shooter. "Templates control by mathematical models on updated microscope." Izvestiya MGTU MAMI 1, no. 2 (January 20, 2007): 214–17. http://dx.doi.org/10.17816/2074-0530-69734.
Повний текст джерелаАнотація:
Modernization of the microscope includes: installation of optical scale systems on the coordinates X, Y; reequipment with personal computer and modern measuring program GeoARM-2D; replacement of contact lens with Renishaw scanning probe. Application of the microscope in contact measurement mode has significant advantages: reduced load on the operator, increasing productivity; increasing objectivity of test results. These advantages are especially noticeable in the control template by the mathematical model.
4
Matoušek, Václav, Jan Krupička, Tomáš Picek, and Štěpán Zrostlík. "Conditions at interfaces of layered flow with intense bed load transport." EPJ Web of Conferences 213 (2019): 02056. http://dx.doi.org/10.1051/epjconf/201921302056.
Повний текст джерелаАнотація:
Intense bed load transport in open channel flow is typically associated with a layered structure of the flow, in which individual layers exhibit different mechanisms of support and friction of transported sediment grains. In the lowermost layer adjacent to the channel bed, the grains slide over each other and maintain virtually permanent contact. In the uppermost layer below the water surface, typically no grains are transported. In the central layer, the grains collide with each other producing typical distributions of granular concentration and velocity across the collisional layer. Mathematical models describing the layered flow with intense bed load (as models based on kinetic theory of granular flows) consider flow conditions at interfaces of the individual layers in their flow predictions. Usually, experimental verification of interfacial predictions is lacking. We exploit results of our new experiments with plastic cylindrical sediment to identify a variation of the conditions at the interfaces (local interfacial granular concentrations and velocities) with varying flow discharge, depth and slope in a laboratory tilting flume. The experimental results include local granular concentration using an improved laser stripe method. The experiments are compared with predictions using our kinetic-theory based transport model with the aim to evaluate a match for experimentally-determined and model-predicted interfacial parameters.
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Cai, Jin, Xiangwei Kong, and Mingzhu Yu. "Mathematical Modeling of Sintering Air Leakage through Holes." Energies 15, no. 12 (June 8, 2022): 4224. http://dx.doi.org/10.3390/en15124224.
Повний текст джерелаАнотація:
The air leakage in sintering machines affects the technological and economic indexes of the sintering process. It is of great significance to monitor and estimate the key areas. Mathematical models of sintering air leakage through holes in the steady-state process are given based on the fluid mechanics to predict the flow rate and effect on the key area. It was found that the hole model is the application of constant orifice outflow in the computation of sintering air leakage. The counter-flow bed model is suitable for predicting the flow rate through a complete break in sintering wind boxes. Furthermore, This paper proposes a new hole–bed generalized model to cover all the possible hole diameters for further high-precision application. The model connects the leakage hole diameter with the sintering process for the first time and establishes their coupling relationship. The pressure state in the sintering system depends on the ratio of the leakage hole area to the sintering bed area. The proposed fast estimation models are a step forward in developing more precise and powerful calculation tools to foresee the effects and consequences of sintering air leakage. It has a good prospect for reducing and replacing complex manual measurement and bringing some insight into the state of the art that could be improved in the future.
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Török, Gergely T., János Józsa, and Sándor Baranya. "Validation of a Novel, Shear Reynolds Number Based Bed Load Transport Calculation Method for Mixed Sediments against Field Measurements." Water 11, no. 10 (September 30, 2019): 2051. http://dx.doi.org/10.3390/w11102051.
Повний текст джерелаАнотація:
In this study, the field measurement-based validation of a novel sediment transport calculation method is presented. River sections with complex bed topography and inhomogeneous bed material composition highlight the need for an improved sediment transport calculation method. The complexity of the morphodynamic features (spatially and temporally varied bed material) can result in the simultaneous appearance of the gravel and finer sand dominated sediment transport (e.g., parallel bed armoring and siltation) at different regions within a shorter river reach. For the improvement purpose of sediment transport calculation in such complex river beds, a novel sediment transport method was elaborated. The base concept of it was the combined use of two already existing empirical sediment transport models. The method was already validated against laboratory measurements. The major goal of this study was the verification of the novel method with a real river case study. The combining of the two sediment transport models was based on the implementation of a recently presented classification method of the locally dominant sediment transport nature (gravel or sand transport dominates). The results were compared with measured bed change maps. The verification clearly referred to the meaningful improvement in the sediment transport calculation by the novel manner in the case of spatially varying bed content.
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Zanden, Joep van der, Dominic A. Van der A, Tom O'Donoghue, David Hurther, Ivan Caceres, Peter D. Thorne, Jebbe J. Van der Werf, Suzanne J. M. H. Hulscher, and Jan S. Ribberink. "SUSPENDED AND BEDLOAD TRANSPORT IN THE SURF ZONE: IMPLICATIONS FOR SAND TRANSPORT MODELS." Coastal Engineering Proceedings, no. 35 (June 23, 2017): 30. http://dx.doi.org/10.9753/icce.v35.sediment.30.
Повний текст джерелаАнотація:
This paper presents results obtained during a large-scale wave flume experiment focused at measuring hydrodynamics and sediment transport processes in the wave breaking region. The experiment involved monochromatic plunging breaking waves over a mobile bed barred profile consisting of D50 = 0.24 mm sand. Vertical profiles of velocity, turbulence, sand concentration and sand fluxes were measured at 12 cross-shore locations, covering the shoaling region up to the inner surf zone. Particularly high-resolution profiles were obtained near the bed within the wave bottom boundary layer, using an acoustic sediment concentration and velocity profiler (ACVP). Sheet flow concentration and particle velocities were measured at two locations near the bar crest using two conductivity-based concentration measurement tanks (CCM+). Total transport rates, obtained from the evolving bed profile measurements, were decomposed into suspended and bedload transport contributions across the bar. The present paper presents a summary of the key findings of the experiment, which are used to discuss existing approaches for modeling suspended and bed load transport in the surf zone.
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Huang, Shichun, Liang Yu, and Weikang Jiang. "Measurement of loudspeaker mechanical impedance by changing the sound load at the throat of loudspeaker." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 1 (August 1, 2021): 5457–66. http://dx.doi.org/10.3397/in-2021-3112.
Повний текст джерелаАнотація:
A loudspeaker is a device that converts electrical energy into acoustic energy by coupling between electrical impedance, mechanical impedance, and radiation impedance. The loudspeaker electro-mechanical-acoustic coupling model provides the experimental feasibility to measure the characteristic parameters. In this paper, an economical and practical measurement method of loudspeaker mechanical impedance is proposed. First, the mathematical relationship between loudspeaker electrical impedance and mechanical impedance is obtained based on the loudspeaker electro-mechanical-acoustic coupling model. Second, two electrical impedances with different known radiation impedance are measured by using a developed measurement system. Finally, the real and imaginary parts of the mechanical impedance are obtained according to the mathematical relationship. This method neither assumes that the loudspeaker mechanical impedance is constant in a frequency band nor does it build FEM models based on structural parameters. A loudspeaker is measured by using a developed measurement system. The result shows that the mechanical impedance and the force factor are functions of frequency. Moreover, a radiation impedance measurement is performed to verify the feasibility and accuracy of the proposed method.
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Хамитов, Максим Сергеевич, Владимир Анатольевич Прокофьев, and Наталья Симовна Бакановичус. "Mathematical simulation of river bed evolution with projected growth for ten years." SCIENCE & TECHNOLOGIES OIL AND OIL PRODUCTS PIPELINE TRANSPORTATION, no. 2 (April 30, 2022): 138–48. http://dx.doi.org/10.28999/2541-9595-2022-12-2-138-148.
Повний текст джерелаАнотація:
Известной проблемой при проектировании подводных транспортных магистралей является прогноз русловых процессов на долгосрочную перспективу. Моделирование транспорта наносов и развития донных деформаций в руслах рек и окрестности гидротехнических сооружений как на физических, так и на численных моделях относится к одной из наиболее сложных и спорных областей гидравлики открытых потоков. Авторами предложено решение задачи долгосрочного прогноза развития русловых деформаций на участке реки Амур в районе расположения основной и резервной ниток подводного перехода магистрального трубопровода Восточная Сибирь - Тихий океан на основе математического моделирования задач гидродинамики и литодинамики в трехмерной постановке. Представлено описание используемой численной модели, учитывающей оползание подводных откосов, закрепленные (ремонтные) участки дна, взвешенные и влекомые наносы. Приводится информация о методике проведения калибровки и валидации численной модели на натурных данных. Обоснован выбор формулы расчета удельного транспорта влекомых наносов, которые имеют определяющее влияние на интенсивность и направленность развития русловых процессов. Приведены сведения, обосновывающие необходимое и достаточное количество слоев многослойной численной модели и размер расчетной ячейки. Расчетный алгоритм реализован на графическом акселераторе GPU, что позволяет за приемлемое время выполнять качественный прогноз деформаций русла на перспективу. Forecast of river bed evolution for the long run is a well-known problem when designing underwater major transport arteries. Simulation of sediment transportation and ground strains development in river beds and vicinities of off-shore structures based on both physical and numerical models is referred to one of the most complicated and disputable areas of open-channel hydraulics. The authors offer a solution of the long-term forecast problem for riverbed strains in the Amur River reach in the area, where the main and standby lines of trunk line submerged crossing “Eastern Siberia - Pacific Ocean” are located, based on mathematical simulation of hydrodynamics and litho-dynamics problems in three-dimensional statement. Description of the used numerical model is presented; the model considers sliding of underwater slopes, fastened (repair) riverbed areas, suspended and bed load deposits. Information on the numerical model calibration and validation in full scale data is given. Selection of a formula for calculation of specific bed load sediments transportation, which have controlling influence on intensity and direction of river bed evolutions development, is justified. Information, which justifies necessary and sufficient quantity of layers of the multilayer numerical model and computational cell size, is given. The computational algorithm is realized on a graphical accelerator GPU, which permits to perform high-quality long-term forecast of river bed strains.
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Karolinczak, Beata, and Wojciech Dąbrowski. "Effectiveness of septage pre-treatment in vertical flow constructed wetlands." Water Science and Technology 76, no. 9 (July 20, 2017): 2544–53. http://dx.doi.org/10.2166/wst.2017.398.
Повний текст джерелаАнотація:
Abstract Septage is wastewater stored temporarily in cesspools. A periodic supply of its significant quantities to small municipal wastewater treatment plants (WWTPs) may cause many operational problems. In the frame of the research, it has been proposed to utilize vertical flow constructed wetlands for pre-treatment of septage prior to its input to the biological stage of a WWTP. The aim of the work was to assess the effectiveness of pre-treatment in relation to factors such as: seasonality, hydraulic load, pollutants load of the VF bed and interactions between these factors. The results proved that application of a VF bed to septage pre-treatment can significantly reduce the concentration of pollutants (biochemical oxygen demand (BOD5): 82%, chemical oxygen demand (COD): 82%, total suspended solids (TSS): 91%, total nitrogen (TN): 47%, ammonia nitrogen (NH4-N): 70%), and thus decrease the loading of the biological stage of a WWTP. The mathematical models of mass removal process were created. They indicate that in case of all analysed parameters, removed load goes up with the increase of load in the influent. However, with the increase of hydraulic load, a decrease of the removed BOD5, COD, TSS and total phosphorus, and in vegetation period an increase of TN, can be observed in terms of load. There are no statistically significant effects of seasonality.
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Wang, Qiang, Yunwen Pan, Kejun Yang, and Ruihua Nie. "Structural Properties of the Static Armor during Formation and Reestablishment in Gravel-Bed Rivers." Water 12, no. 7 (June 28, 2020): 1845. http://dx.doi.org/10.3390/w12071845.
Повний текст джерелаАнотація:
The formation and reestablishment of bed structural properties in the static armor layer is an important research subject. To address this issue, we conducted a series of static armor layer experiments in a laboratory flume that focused on formation and reestablishment. Through an automatic measurement system, we obtained a real-time bed load transport rate. The bed surface elevation at different flow intensities was obtained using a PTS (Photo Terrain Scanning) system. The results show that the formation and reestablishment of the bed load transport rate in the static armor layer increased from zero to its peak before decaying. The bed structure response was found to be highly dependent on the unevenness of the bed surface elevation. The bed surface elevation of a static armor layer in a laboratory flume is considered as a two-dimensional random field. In a two-dimensional random field, the changes in bed elevation are characterized using statistical parameters. Statistical parameters are evaluated from precise digital elevation models (DEMs) of bed surfaces. Experimental results provide the change of probability distribution functions (PDFs) and second-order structure functions of bed elevations between formation and reestablishment after breaking the static armor layer. By quantitatively analyzing the changes in these statistical parameters, we quantified the difference between the bed structure in the static armor layer formation and the new static armor layer formed after being broken. Thus, this finding reveals that the bed structure of the static armor layer formed by different flow intensities is different, and this difference can be quantified using statistical methods.
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Buchta, Vojtech. "Experimental Testing the Interaction of Fiber-Concrete Foundation Slab and Subsoil and Compare the Results with Numerical Models." Advanced Materials Research 1020 (October 2014): 227–32. http://dx.doi.org/10.4028/www.scientific.net/amr.1020.227.
Повний текст джерелаАнотація:
We solve interaction between the foundation base and the subsoil in civil engineering quite often. For the determination of stress in foundation structure is needed to determine the influence of the stiffness respectively pliability of subsoil to structural internal forces, and vice versa, how the stiffness of the foundation structure affects the resulting subsidence. It is necessary to compare the mathematical models with the actual behavior of the real structure. In 2013 was realised static load on testing equipment in the campus of Faculty of Civil Engineering, VSB–TU Ostrava. Dimensions of test element was 2000 x 2000 x 170 mm and the concrete slab was reinforced with steel fiber type DRAMIX 3D 65/60B6. During measurements were performed and recorded: tensometrical measurement on the surface of the slab, tensometrical measurement inside the slab, measuring the vertical load, measurement of the vertical deformation, measuring the stress on the interface of the slab and soil. Were also developed numerical models of this test in program Nexis. Comparison the test results with numerical models are presented in this paper. [1,9]
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Rahimi-Ahar, Zohreh, and Mohammad Sadegh Hatamipour. "Hydrodynamics, numerical study and application of spouted bed." Reviews in Chemical Engineering 34, no. 6 (November 27, 2018): 743–66. http://dx.doi.org/10.1515/revce-2017-0036.
Повний текст джерелаАнотація:
Abstract This article reviews the major research and development on spouted beds (SBs). Due to its unique structural and flow characteristics, the SB is a very successful system in most applications. Two-phase and sometimes three-phase interactions generate a large number of variables to be noted in each process. Up-to-date information on the fundamentals and applications of SBs has been briefly presented, based on the published works. Thousands of interesting studies on hydrodynamic characteristics, numerical simulations, and new applications of SBs are reported. In the first step, the present work presents a review of hydrodynamic characteristics (circulation of solids in SB, measurement techniques for particle tracking and empirical hydrodynamics, pressure drop, maximum spoutable height, minimum spouting velocity, and diameter of the spout). In the second step, main mathematical models and computational fluid dynamics (CFD) simulation of the SB to predict and analyze different processes are described. Some main mathematical modeling and the recent advances of two fluid methods and discrete element method approaches in CFD simulation of SBs are summarized. In the last step, some new applications of the SB are presented. As the result of this review, we can observe the importance of further development of hydrodynamics structure, working on modeling and related correlations and improve the applications of SBs.
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Willis, David H., and B. G. Krishnappan. "Numerical modelling of cohesive sediment transport in rivers." Canadian Journal of Civil Engineering 31, no. 5 (October 1, 2004): 749–58. http://dx.doi.org/10.1139/l04-043.
Повний текст джерелаАнотація:
Techniques available to practicing civil engineers for numerically modelling cohesive mud in rivers and estuaries are reviewed. Coupled models, treating water and sediment as a single process, remain research tools but are usually not three-dimensional. The decoupled approach, which separates water and sediment computations at each model time step, allows the three-dimensional representation of at least the bed and the use of well-proven, commercial, numerical, hydrodynamic models. Most hydrodynamic models compute sediment transport in suspension but may require modification of the dispersion coefficients to account for the presence of sediment. The sediment model deals with the sediment exchange between the water column and the bed using existing equations for erosion and deposition. Both equations relate the sediment exchange rates to the shear stress in the bottom boundary layer. In real rivers and estuaries, a depositional bed layer is associated with a period of low flow and shear, at slack tide for example, whereas in numerical models a layer is defined by the model time step. The sediment model keeps track of the uppermost layers at each model grid point, including consolidation and strengthening. Although numerical hydrodynamic models are based strongly on physics, sediment models are only numerical frameworks for interpolating and extrapolating full-scale field or laboratory measurements of "hydraulic sediment parameters," such as threshold shear stresses. Calibration and verification of models against measurement are therefore of prime importance.Key words: cohesive sediment, mathematical modelling, settling velocity, erosion, resuspension, deposition, fluid mud, bed layers.
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Klyapko, V. A., and N. N. Maiorov. "FORMATION OF REQUIREMENTS FOR THE INFORMATION-ANALYTICAL SYSTEM BASED ON THE USE OF MATHEMATICAL MODELS OF PREDICTION AND SIMULATION MODELS OF VIRUS PROPAGATION." System analysis and logistics 4, no. 34 (December 20, 2022): 52–60. http://dx.doi.org/10.31799/2077-5687-2022-4-52-60.
Повний текст джерелаАнотація:
Key trends in the development of a modern megalopolis, in the period of large-scale loads on the health care system, in the period of the spread of viruses, encourage the use of advanced methods and approaches to the organization of work in the field of health care. The object of the research is the city of St. Petersburg, the analysis of the main indicators of the load on the city's health care system has been carried out. The changes in the system processes caused by the long-term influence of coronavirus infection (COVID-19) are substantiated. The scientometric analysis reflecting the necessity of introduction of information systems and services in the health care system was performed. Analysis of models and methods (SIR, ARIMA, Holt-Winters) for the task of forecasting is presented and simulation models of virus spread are presented. The practical task of forecasting the number of hospitalizations of patients to estimate hospital bed capacity is presented. The use of forecasting and simulation modules of virus distribution in the information-analytical system is substantiated to make a decision on the estimation of necessary capacity of the health care system.
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Mlynek, P., J. Misurec, and M. Koutny. "Random Channel Generator for Indoor Power Line Communication." Measurement Science Review 13, no. 4 (August 1, 2013): 206–13. http://dx.doi.org/10.2478/msr-2013-0032.
Повний текст джерелаАнотація:
The paper deals with creating an indoor power line model based on random parameters. This model approximates the real parameters of the power line communication with sufficient precision. A detailed analysis of earlier and current research in power line communication modelling, especially for power line models, is described. Measurement of transmission line parameters and power line model verification follows. Based on model analysis and load impedance measurement, a mathematical description of the model is designed. A reference model for different scenarios is realized too. The last part gives the analysis of this model and simulation results.
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Liffman, Kurt, Ilija D. Šutalo, Anh Bui, Michael M. D. Lawrence-Brown, and James B. Semmens. "Experimental Measurement and Mathematical Modeling of Pulsatile Forces on a Symmetric, Bifurcated Endoluminal Stent Graft Model." Vascular 17, no. 4 (August 1, 2009): 201–9. http://dx.doi.org/10.2310/6670.2009.00036.
Повний текст джерелаАнотація:
The objective of this study was to measure the pulsatile forces acting on a symmetric, bifurcated endoluminal stent graft to validate a computational fluid dynamics (CFD) and analytic model so that they can be used for various graft dimensions. We used a load cell to measure the force owing to the movement of an acrylic model of a bifurcated stent graft under pulsatile flow. This was then simulated with a CFD and analytic model. The main features of the experimental pulsatile force data and the CFD results were consistent. The results showed that the total force was proportional to the inlet pressure cycle. The force rose from 3.32 N at 130 mm Hg systolic to 17.5 N at 250 mm Hg systolic pressure. For the more variable regions of the flow, the experimentally measured forces lagged the computational and analytic results. The CFD and analytic models provide approximate descriptions for the forces acting on a bifurcated stent graft subjected to pulsatile flow. Such models should be of assistance to designers of endoluminal stent grafts.
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Garmendia, Iñaki, and Eva Anglada. "Influence of the Measurements Uncertainties in the Correlation of Spacecraft Thermal Models against Thermal Results." Aerospace 9, no. 12 (December 14, 2022): 821. http://dx.doi.org/10.3390/aerospace9120821.
Повний текст джерелаАнотація:
Ground thermal tests are always mandatory before any space mission is flown into space. The collected results of these tests are mainly temperatures of the different parts of the spacecraft (nodes) for different mission scenarios. The measured temperatures always show differences with the expected values coming from the computer thermal mathematical models. The origin of these differences is partially related to the inherent error coming from physical measurements. The thermal parameters that compose the computer thermal mathematical models must always be correlated with the results coming from tests. This paper studies, through three thermal models, the difficulties that are found in the correlation process when the measured temperatures reach a certain level of error. Thermal parameters become more difficult to be identified when the measurement error level increases. However, the temperature fields obtained with these poor thermal parameters are good enough for the mission thermal analysis. Several error levels, different load cases and correlation for steady-state and transient cases are studied to probe these findings.
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Khasanov, I. R., A. V. Karpov, S. F. Lobova та N. V. Petrova. "Field modeling of the fire dynamics as an answer to the question about the fire alarm performance". Pozharovzryvobezopasnost/Fire and Explosion Safety 29, № 5 (2 грудня 2020): 40–50. http://dx.doi.org/10.22227/pvb.2020.29.05.40-50.
Повний текст джерелаАнотація:
Introduction. The performance of a fire alarm needs to be analyzed to answer the question about its compliance with fire safety requirements. This type of research is frequently performed in the course of a forensic fire investigation. Therefore, it is necessary to identify conditions of fire escalation and safe evacuation of people to assess the fire alarm performance.Purposes and objectives. The purpose of this work is the numerical study of the impact, produced by mathematical models of combustion, characteristics of fire loads and locations of fire beds, on fire alarm performance. Methods. Fire dynamics was field modeled to achieve the goal of this research. The analysis of flame propagation was performed with regard for various fire bed locations to simulate the fire alarm operation.Results and discussion. The fulfillment of safe evacuation conditions for cases of irregular arrangement of smoke detectors was analyzed to develop and test the algorithm for the calculation of the evacuation start time. It is shown that the estimated time of fire detection depends on combustion models employed (their average or complex level), the size of the computational grid, fire load specifications and the location of the fire bed.Conclusions. It is shown that the results of the field modeling of fire propagation and detection time are influenced by combustion models used, fire load specifications and the location of the fire bed in relation to smoke detectors. If the fire alarm fails to perform its functions and, consequently, safe evacuation conditions are not fulfilled, it is necessary either to improve the combustion model or to compare the modeling results obtained for actual and standard smoke detector location patterns.
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Peng, Huiming, G. Maksim Popov, Feng Li, and Zhiyu Lu. "Dynamic Identification of Equivalent Parameters of Mathematical Models of Power Electrical Equipment of Electromechanical Power Systems." Journal of Physics: Conference Series 2166, no. 1 (January 1, 2022): 012024. http://dx.doi.org/10.1088/1742-6596/2166/1/012024.
Повний текст джерелаАнотація:
Abstract The article describes a method for dynamic identification of AC and DC hybrid power network parameters. The inaccuracy of the parameters of the electromechanical transient simulation model of the power system has caused the obvious difference between the simulation results and the actual measurement, which has restricted its online application. Over the years, the dynamic parameter identification technology based on field test and test has made great progress, but it is far from satisfactory and accurate. There is still a long research journey for the requirements of performance. The online identification method based on the actual dynamic parameters of the power system is a way to solve the problem. The article includes the main microprocessor modules for system parametric identification of load (SIP L) and an overhead power transmission line (SIP TL). The article will analyze the active electrical network and passive electrical network
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Jocea, Andreea Florina, E. G. Crăciun, and A. Anton. "Approximation Of Scours Using Terrestrial 3D Laser Scanning." Journal of Applied Engineering Sciences 5, no. 1 (May 1, 2015): 31–36. http://dx.doi.org/10.1515/jaes-2015-0004.
Повний текст джерелаАнотація:
Abstract In designing artwork as bridges, hydraulic calculations have a very important role due to the fact that they are behind their sizing. Bridge designer must therefore possess knowledge of hydrology, hydraulics of bridges and river banks regularization. A problem that arises during the design stage of bridges is the scour phenomenon surrounding bridge pier. Over time, there have been conducted a number of studies which led to the provision of a plurality of mathematical models that are intended scour prediction. In the present article we will present an experimental study to determine the bed profile and measurement of scours products around a pier bridge using 3D terrestrial laser scanner.
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Cho, Seung-Young, Min-Seob Kim, Young-Sik Pyun, and Do-Sik Shim. "Strategy for Surface Post-Processing of AISI 316L Additively Manufactured by Powder Bed Fusion Using Ultrasonic Nanocrystal Surface Modification." Metals 11, no. 5 (May 20, 2021): 843. http://dx.doi.org/10.3390/met11050843.
Повний текст джерелаАнотація:
Ultrasonic nanocrystal surface modification (UNSM) technology was applied to the surfaces of specimens additively manufactured by powder bed fusion (PBF). The changes in roughness and hardness due to the UNSM were set as objective functions, and the optimal conditions for the main parameters were derived through the response surface method (RSM) and Box–Behnken design (BBD). Regression analysis-based mathematical models for predicting the surface hardness and roughness are presented and validated. The RSM results show that the surface roughness is highly dependent on the load and ball tip diameter, and the surface roughness significantly improves as the inter-pass interval and ball tip diameter decrease. Through BBD and ANOVA, the optimal conditions for the improvement of surface characteristics were found to be a load of 40 N, inter-pass interval of 10 μm, and ball tip diameter of 2.38 m. The surface treated under these optimal conditions exhibited a hardness of 497 Hv and surface roughness of 1.32 μm, which were significantly improved compared to the values for an untreated specimen. In addition, it was confirmed that the grains are significantly refined after UNSM, and scratch resistance increases for the top layer of the surface directly affected by the UNSM horn.
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Valentino, Tobias, Marian Höhmann, Kevin Schünemann, Jonas Wentzler, Tim Wünderlich, Tim Radel, and Frank Vollertsen. "Time-Resolved Force Measurements to Determine Positioning Tolerances for Impulse-Based Indentations." Lasers in Manufacturing and Materials Processing 8, no. 2 (May 31, 2021): 216–35. http://dx.doi.org/10.1007/s40516-021-00140-8.
Повний текст джерелаАнотація:
AbstractHigh-throughput experimentation methods determine characteristic values, which are correlated with material properties by means of mathematical models. Here, an indentation method based on laser-induced shock waves is presented, which predicts the material properties, such as hardness and tensile strength, by the induced plastic deformation in the substrate material. The shock wave pushes a spherical indenter inside a substrate material. For reproducible indentations, the applied load is of importance. To compare different processes and process parameters, the measured plastic deformation is normalized by the applied load. However, eccentric irradiation leads to altered beam profiles on the surface of spherical indenters and the angle of incidence is changed. Thus, the influence of eccentric irradiation is studied with an adapted time-resolved force measurement setup to determine the required positioning tolerances. The spherical indenter is placed inside a cylindrical pressure cell to increase the laser-induced shock pressure. From the validated time-resolved force measurement method we derive that deviations from the indentation forces are acceptable, when the lateral deviation of the beam center, which depends only on the alignment of the setup, does not exceed ± 0.4 mm. A vertical displacement from the focus position between -3.0 mm and + 2.0 mm still leads to acceptable deviations from the indentation force.
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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.
Повний текст джерелаАнотація:
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.
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Yohanes, Barep, and Feby Indriana Yusuf. "Intrinsic Cognitive Load in Online Learning Model of School Mathematics 1 in Covid-19 Pandemic Period." JIPM (Jurnal Ilmiah Pendidikan Matematika) 9, no. 2 (February 2, 2021): 59. http://dx.doi.org/10.25273/jipm.v9i2.7292.
Повний текст джерелаАнотація:
<p class="JRPMAbstrakTitle">The study aims at determining the emergence of intrinsic cognitive load in online learning models of School Mathematics 1 in Covid-19 pandemic period. This research is a descriptive qualitative one the data of which are obtained from observation sheets, questionnaires and interview results. Validity checking uses the triangulation method. The results of the study show that the intrinsic cognitive load is caused by the interactivity and isolated/interacting elements contained in the learning process. Elements of interactivity are in the form of terms or concepts in Mathematics learning. These terms or concepts, for examples, are the meaning of Knowledge, Standard Measurement, Mathematical Approach, Intertwined Principles, Content, Context, Competence, PISA Learning Concepts, De-conceptualization, Systems Approach, Conceptual Approach, etc. Isolated/interacting elements are seen from looking for examples of implementation in the real world and actualization of events in Indonesia. An example of implementation in the real world is an element that interacts in real situations in the learning practice of Mathematics.</p>
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Peres, André B., Mário C. Espada, Fernando J. Santos, Ricardo A. M. Robalo, Amândio A. P. Dias, Jesús Muñoz-Jiménez, Andrei Sancassani, Danilo A. Massini, and Dalton M. Pessôa Filho. "Accuracy of Hidden Markov Models in Identifying Alterations in Movement Patterns during Biceps-Curl Weight-Lifting Exercise." Applied Sciences 13, no. 1 (December 31, 2022): 573. http://dx.doi.org/10.3390/app13010573.
Повний текст джерелаАнотація:
This paper presents a comparison of mathematical and cinematic motion analysis regarding the accuracy of the detection of alterations in the patterns of positional sequence during biceps-curl lifting exercise. Two different methods, one with and one without metric data from the environment, were used to identify the changes. Ten volunteers performed a standing biceps-curl exercise with additional loads. A smartphone recorded their movements in the sagittal plane, providing information on joints and barbell sequential position changes during each lift attempt. An analysis of variance revealed significant differences in joint position (p < 0.05) among executions with three different loads. Hidden Markov models were trained with data from the bi-dimensional coordinates of the joint positional sequence to identify meaningful alteration with load increment. Tests of agreement tests between the results provided by the models with the environmental measurements, as well as those from image coordinates, were performed. The results demonstrated that it is possible to efficiently detect changes in the patterns of positional sequence with and without the necessity of measurement and/or environmental control, reaching an agreement of 86% between each other, and 100% and 86% for each respective method to the results of ANOVA. The method developed in this study illustrates the viability of smartphone camera use for identifying positional adjustments due to the inability to control limbs in an adequate range of motion with increasing load during a lifting task.
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Tamás, Enikő Anna, and Johanna Ficsor. "Questions in the quantitative analysis of sediment load - example of three major rivers in Hungary." E3S Web of Conferences 40 (2018): 04023. http://dx.doi.org/10.1051/e3sconf/20184004023.
Повний текст джерелаАнотація:
The importance of the monitoring of sediment processes is unquestionable: sediment balance of regulated rivers suffered substantial alterations in the past century, affecting navigation, energy production, fish habitats and ecosystems alike. The changes in flood characteristics and rating curves of our rivers are being researched and described, involving state-of-the-art measurement methods, modeling tools and traditional statistics. Sediment processes however, are much less known. Sediment-related research is scarce, which is partly due to the outdated methodology and poor database background in the specific field. Regular sediment sampling was developed in the first half of the 20th century, with different station density and monitoring frequencies in different countries. Sampling frequency of suspended load is 3 to 7 per year in Hungary, and even lower for the bed-load, not only on the Danube river but also on large tributaries like the Drava and the Tisza rivers. Data related to sediment quantity are unreliable and often contradictory. It is difficult to produce high quality long-term databases that could enable the calibration of sediment transport models. It is a challenge to compare measurements on international rivers. The authors give an overview of sediment sampling methods, an inventory of the available datasets and data management in Hungary on the rivers Danube, Drava and Tisza, based on field data.
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Mizuguchi, Hiroshi, Mikio Iwakiri, Yutaka Ido, and Hidenori Shinno. "A Real-Time Measuring Method of Spindle Center Transition for NC Lathe." International Journal of Automation Technology 2, no. 6 (November 5, 2008): 486–91. http://dx.doi.org/10.20965/ijat.2008.p0486.
Повний текст джерелаАнотація:
Thermal displacement in the spindle system has great influence on the machining accuracy. Therefore it is very important to evaluate the thermal displacement of the spindle precisely. In the conventional measurement method for thermal displacement of the spindle, the measurements were taken during no-load running with non-contact sensors put close to the outside of a workpiece. However, in fact, it is essential to evaluate thermal displacement of the spindle while a machine tool is machining a workpiece actually. The measurement of the thermal displacement of the spindle during actual machining is generally difficult. In this paper, we propose a new method by which we measure thermal displacement of the spindle while we are actually machining a workpiece with an NC lathe. The experiment was performed with various cutting conditions and the result of the thermal displacement of the spindle corresponding to each condition was observed. Then, by analyzing the experimental result, we obtained mathematical models that show the relation between thermal displacement and spindle motor output.
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Wan, Peng, Jun Jie Guo, and Jin Dong Wang. "Research on the Method of Continuous Scanning Measurement on the Tooth Surface of the Spiral Bevel Gear Based on the Constant Measuring Force." Advanced Materials Research 468-471 (February 2012): 1532–40. http://dx.doi.org/10.4028/www.scientific.net/amr.468-471.1532.
Повний текст джерелаАнотація:
In the measurement process of the large, complex surface, due to the errors of the installation, the errors of the machine bed itself and other factors, the probe can be over pressed. The situation of measuring interruption can be occurred. In the paper, take the measurement of the spiral bevel gear for example, by using of the gear meshing theory and differential geometry, through a series of coordinate transformations, the coordinates of the tooth surface grid nodes are calculated. Through measuring the tooth surface of the spiral bevel gear by using of Gear Measuring Center(GMC) and 3D scanning probe system, the follow-up control strategy of continuous scanning measurement based on the constant measuring force was proposed. The measurement and evaluation of the tooth surface were achieved through continuous scanning motion along the measurement path planned. In the measurement process, the measurement path was planned according to the theoretical models. The offset values of the probe were real-time detected, the constant deformation of the probe was ensured through controlling the motion of X,Y,Z axes. The mathematical model of the relationship between the velocity of each axis and the deformation vector of the probe was established. The continuous scanning measurement along the path planned based on the constant measuring force can be implemented. The requirement of the steady-state errors and real-time were meted by using of PID control strategy of subsection variable parameters. The method was finally simulated and experimented. The results showed that the occurrence of unexpected interruption in the measuring process can be effectively solved. It plays an important role for the highly-efficient and highly-precise measurements of the tooth surface.
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Elaiyarasan, Uthirapathi, Vinaitheerthan Satheeshkumar, and Chinnamuthu Senthilkumar. "Surface modification of a magnesium alloy by electrical discharge coating with a powder metallurgy electrode." Materials Testing 63, no. 4 (April 1, 2021): 360–67. http://dx.doi.org/10.1515/mt-2020-0054.
Повний текст джерелаАнотація:
Abstract The present paper elucidates an experimental study on the surface modification of a ZE41 A magnesium alloy by electrical discharge coating (EDC) process with a tungsten carbide-copper (WC-Cu) powder metallurgy (PM) electrode. Investigated EDC parameters were compaction load, current and pulse on time. Measurement of coating characteristics such as material transfer rate (MTR) and surface roughness (Ra) were undertaken on the coated workpiece. As the design of experiment, response surface methodology was applied and analysis of variance (ANOVA) test was completed to study the influence of process parameters. Mathematical models were developed for coating characteristics to optimize the parameters. In this study, the reliability of the regression model is considered satisfactory with a value larger than 99 %. It was found from the study that the current plays a vital role in increasing the material transfer rate and minimizing the surface roughness of the coated surface followed by compaction load and pulse on time. Various studies such as scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were carried out to determine the characteristics of the coated layer. These analyses confirmed the presence of the electrode materials in the coated surface.
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Bihari, Péter, Gyula Gróf, and Iván Gács. "Efficiency and cost modelling of thermal power plants." Thermal Science 14, no. 3 (2010): 821–34. http://dx.doi.org/10.2298/tsci1003821b.
Повний текст джерелаАнотація:
The proper characterization of energy suppliers is one of the most important components in the modelling of the supply/demand relations of the electricity market. Power generation capacity i. e. power plants constitute the supply side of the relation in the electricity market. The supply of power stations develops as the power stations attempt to achieve the greatest profit possible with the given prices and other limitations. The cost of operation and the cost of load increment are thus the most important characteristics of their behaviour on the market. In most electricity market models, however, it is not taken into account that the efficiency of a power station also depends on the level of the load, on the type and age of the power plant, and on environmental considerations. The trade in electricity on the free market cannot rely on models where these essential parameters are omitted. Such an incomplete model could lead to a situation where a particular power station would be run either only at its full capacity or else be entirely deactivated depending on the prices prevailing on the free market. The reality is rather that the marginal cost of power generation might also be described by a function using the efficiency function. The derived marginal cost function gives the supply curve of the power station. The load level dependent efficiency function can be used not only for market modelling, but also for determining the pollutant and CO2 emissions of the power station, as well as shedding light on the conditions for successfully entering the market. Based on the measurement data our paper presents mathematical models that might be used for the determination of the load dependent efficiency functions of coal, oil, or gas fuelled power stations (steam turbine, gas turbine, combined cycle) and IC engine based combined heat and power stations. These efficiency functions could also contribute to modelling market conditions and determining the environmental impact of power stations.
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Rajinikanth, V., and K. Latha. "Modeling, Analysis, and Intelligent Controller Tuning for a Bioreactor: A Simulation Study." ISRN Chemical Engineering 2012 (December 30, 2012): 1–15. http://dx.doi.org/10.5402/2012/413657.
Повний текст джерелаАнотація:
In this paper, a novel modeling technique has been attempted to develop the mathematical model for a bioreactor functioning at multiple operating regions. The first principle mathematical equations of the reactor are used with the POLYMATH software to generate essential data for the model development. A relative analysis is also carried out with the existing models in the literature. An optimal PID controller is then designed using a multiobjective particle swarm optimization algorithm. The controller tuning procedure is individually discussed for both the stable and unstable steady state regions. The controller tuned for each region is scheduled using a set-point scheduler to achieve a complete control over the bioreactor. The effectiveness of the proposed scheme has been confirmed through a comparative study with the controller tuning methods proposed in the literature. The results show that, the proposed method provides enhanced performance in effective reference tracking and load disturbance rejection with minimal ISE and IAE. Finally the proposed method is validated on the nonlinear bioreactor model in the presence of a measurement noise. The results testify that the PSO tuned PID performs well in tracking the change in biomass concentration at the entire operating region.
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Mullings, Hannah, and Tim Stallard. "Impact of spatially varying flow conditions on the prediction of fatigue loads of a tidal turbine." International Marine Energy Journal 5, no. 1 (June 21, 2022): 103–11. http://dx.doi.org/10.36688/imej.5.103-111.
Повний текст джерелаАнотація:
Site development for tidal turbines relies upon a good understanding of the onset flow conditions, with disk averaged velocity typically used as a reference to define turbine power and mean loading. This work investigates the variation of onset flow conditions which occur for the same disk averaged velocity. Analysis builds upon data previously acquired during the measurement campaign conducted for the ReDAPT project using bed mounted ADCPs \cite{Sellar2018}. These measurements define the turbulence characteristics and vertical shear profiles over the rotor plane which are incorporated into an efficient blade element method for prediction of unsteady blade loads. This method allows efficient calculation of blade loading for multiple onset shear and turbulence profiles, each with the same disk average velocity, to determine the cyclic loading which contributes towards fatigue. Predictions of fatigue loads from measured profiles are compared with predictions from profiles predicted for the same location with a MIKE3 model \cite{Gunn2014}. Within the water depth two vertical positions are analysed, with vertical shear profiles from measurements and a multi-parameter model used to define the onset. For a near-bed location, use of the averaged predicted velocity profiles neglecting variation of turbulence intensity with flow-speed provides fatigue loads to within 1\% of predictions obtained using all measured profiles of velocity and corresponding turbulence intensity. For the near-surface location, the same approach under predicts fatigue loads by 16-19\%. This is partly due to the occurrence of a wider range of turbulence intensities. Since this is nearly constant with flow-speed a scaling factor is applied to load cycles from predicted profiles to estimate the aggregated fatigue load obtained using all measured conditions, providing confidence that accumulated fatigue loads can be predicted efficiently from velocity profiles obtained from shallow water models.
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Belaid, Saloua, Djamila Rekioua, Adel Oubelaid, Djamel Ziane, and Toufik Rekioua. "Proposed Hybrid Power Optimization for Wind Turbine/Battery System." Periodica Polytechnica Electrical Engineering and Computer Science 66, no. 1 (January 17, 2022): 60–71. http://dx.doi.org/10.3311/ppee.18758.
Повний текст джерелаАнотація:
This paper contributes to the feasibility of a wind turbine/battery system with a hybrid power optimization controller. The proposed method is based on a mathematical optimization approach and allows to achieve an efficient operation of the maximum power point tracking (MPPT) algorithms to obtain an optimal performance level of the wind system and a minimal stress on the battery storage. The different powers have been controlled by a power management control (PMC) method. The objectives of the PMC based are, in first part to satisfy the load power demand and in second part to maintain the state of charge of the battery bank to prevent blackout and to extend the batteries life. A measurement of wind speeds was made during a whole day using a data acquisition system at the laboratory. Also, the different wind turbine parameters were identified at the same Laboratory. All these parameters have been used in simulation models in order to obtain the most realistic mathematical models that are close to the experiment. Real time simulation is performed using RT LAB simulator and the obtained results were matching those obtained in numerical simulation using Matlab/Simulink. The obtained results under two different wind speed profile, with the different comparisons are presented to show the feasibility and the improvement of the proposed study in terms of power, efficiency, time response and effect on battery state of charge under two different wind speeds profile.
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Stara, Marie. "Testing of Pre-Stressing Masonry Wall with Using Different Thickness of Anchor Plates." Advanced Materials Research 1082 (December 2014): 211–15. http://dx.doi.org/10.4028/www.scientific.net/amr.1082.211.
Повний текст джерелаАнотація:
Contribution deals with experimental measurements of deformations in the place exposed to local load caused by additional pre-stressing. The measurements are made at the masonry brick corner built in the laboratory equipment. The laboratory equipment was designed at Faculty of Civil Engineering VŠB – TU Ostrava for measurement tri-axial stress-strain conditions in masonry. In this brick corner one pre-stressing bar is placed. And on the pre-stressing bar is anchored to the anchor plate which transfer pre-stressing forces to the masonry. The thickness of brick corner is 440mm and anchor plate will be used about thickness 10, 20 and 30mm. Mathematical modelling of brick corner is based on finite element method using software ANSYS and then the results are compared with results of laboratory tests. On the basis of these results it should be possible to improve the models and to approach closer to the accurate and at the same time simple procedure for design of pre-stressed masonry.
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Ornatskyi, D. P., D. M. Kvashuk, and M. O. Kataieva. "METHODS OF MEASUREMENT OF PERFORMANCE CHARACTERISTICS OF ELECTRIC GENERATORS." Key title: Zbìrnik naukovih pracʹ Odesʹkoï deržavnoï akademìï tehnìčnogo regulûvannâ ta âkostì, no. 2(19) (2021): 37–47. http://dx.doi.org/10.32684/2412-5288-2021-2-19-37-47.
Повний текст джерелаАнотація:
The article investigates the methods and means of measuring the operating characteristics of elec-tric generators, namely the output voltage, resistance, frequency, current and torque. The analysis of literature sources that characterize the structural elements and the principle of operation of synchro-nous generators is carried out. Methods of measuring the operating characteristics of electric genera-tors are studied. Mathematical models that describe the relationships between physical quantities that characterize the parameters of electric generators are considered. The estimation of modern direc-tions of development of means of measurement of torques of electric generators is carried out. Meth-ods of data processing and visualization obtained by primary devices are studied. The dependence of the torque of electric generators and their output parameters is studied. A block diagram of a digital measuring sensor is constructed, which shows the main components of a device for measuring torque using an inductive sensor. Based on research, a method for measuring torque using an inductive sensor has been proposed, which allows increasing the sensitivity of the measurement by improving the metrological characteris-tics of the measuring channel. This improvement is that the coils that change their inductance under the action of torsional load on the motor shaft are not affected by electromagnetic interference created by the generator during operation. Simulation of the electrical circuit using the proposed method al-lowed to obtain the attenuation coefficient of the in-phase signal 80 dB at an input signal frequency of 10 kHz, thus providing high sensitivity. This model was tested, which made it possible to obtain errors in the simulation in the operating mode. The standard deviation and the absolute measurement error are determined. The Matlab / Simulink modeling complex was used to process the measurement results and study the errors, which allowed visualizing the transient characteristics of the measuring signal and obtain a possible error.
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Magomedbekov, Eldar P., Aleksei O. Merkushkin, Veronika S. Pokalchuk, Alexander V. Obruchikov, Ilia Yu Lukiyanchikov, Alexander S. Chepurnov, and Elena A. Vanina. "Calculation of the Henry’s Constant and the Thickness of the Equilibrium Adsorption Layer of Radon in the Layer-by-Layer Measurement of the Sorbent Activity." Energies 15, no. 24 (December 16, 2022): 9569. http://dx.doi.org/10.3390/en15249569.
Повний текст джерелаАнотація:
The radioactive gas radon is ubiquitous in the environment and is a major contributor to the human inhalation dose. It is the second leading cause of lung cancer after smoking. Radon concentrations are particularly high in the air of radon-hazardous facilities—uranium mines and radioactive waste repositories containing radium. To reduce the dose load on the staff, air in these premises should be continuously or periodically purified of radon. Carbon adsorbers can be successfully used for this purpose. The design of sorption systems requires information on both equilibrium and kinetic parameters of radon dynamic adsorption. The traditional way of obtaining such characteristics of the sorbent is to analyze the breakthrough curves. The present paper proposes a simple alternative method for determining parameters of dynamic radon adsorption (Henry’s constant and equilibrium adsorption layer thickness) from the results of a layer-by-layer gamma-spectrometric measurement of the sorbent. The analytical equation for smooth distribution of radon activity in the sorbent layer is obtained based on equilibrium adsorption layer theory for elute chromatography (pulsed injection of radon into the column). Using the dynamic adsorption of 222Rn on AG-3 activated carbon as an example, both equilibrium (Henry’s constant) and kinetic (thickness of the equilibrium adsorption layer) parameters of the adsorption dynamics were calculated. It was shown that the exposure duration of the column bed in the air flow and superficial gas velocity do not affect the result of the Henry’s constant calculation. The dependence of the equilibrium adsorption layer thickness on the superficial gas velocity over a wide range of values (5–220 cm/min) is described by the van Deemter equation. It was shown that the optimum air flow velocity, which corresponds to the maximum effectiveness of the bed, is 15–30 cm/min. This corresponds to the minimum of the equilibrium adsorption layer thickness (about 0.6 cm). The developed mathematical model makes it easy to define both equilibrium and kinetic parameters of dynamic adsorption of radon based on discrete distribution of its activity over the sections of the adsorption column. These parameters can then be used to calculate and design gas delay systems. It can be useful for studying the sorption capacity of various materials relative to radon.
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Fraser, S., M. H. Attia, and M. O. M. Osman. "Modelling, Identification and Control of Thermal Deformation of Machine Tool Structures, Part 1: Concept of Generalized Modelling." Journal of Manufacturing Science and Engineering 120, no. 3 (August 1, 1998): 623–31. http://dx.doi.org/10.1115/1.2830167.
Повний текст джерелаАнотація:
With the increasing demand for improved machining accuracy in recent years, the problem of thermal deformation of machine tool structures is becoming more critical than ever. In spite of the effort for improving the thermal deformation characteristics of machine tools at the design stage, there are always some residual errors that have to be compensated for during machining. The design of a generic multi-axis control system requires the development of two models to estimate the transient thermal load and to estimate the thermal deformation of the structure in real-time. To satisfy the stringent accuracy and stability requirements of these two models, a new concept of “generalized modelling” is introduced. It combines mathematical modelling with empirical calibration, and is based on the existence of a mathematical similarity between the real process and a simplified model, referred to as the fundamental generalized problem FGP. To obtain an analytical description of the heat transfer and thermal deformation processes in machine tool structures, an analytical solution of the FGP, which consists of an infinite plate with a central ring heat source, is derived using Hankel transformation. Computer-simulated test cases are presented to demonstrate the use of generalized modelling for predicting the transient thermal response in a complex machine tool structure. It was also shown how the generalized model can accurately extrapolate limited measurement data to predict the entire temperature field. The results confirmed that the generalized model can reproduce the accuracy of the finite-element solution, but two orders of magnitude faster.
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Pankova, B., T. Koudelka, K. Pavelka, M. Janura, and K. Jelen. "EXPLOITATION OF STEREOPHOTOGRAMMETRIC MEASUREMENT OF A FOOT IN ANALYSIS OF PLANTAR PRESSURE DISTRIBUTION." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences III-5 (June 6, 2016): 153–58. http://dx.doi.org/10.5194/isprsannals-iii-5-153-2016.
Повний текст джерелаАнотація:
Stereophotogrammetry as a method for the surface scanning can be used to capture some properties of the human body parts. The objective of this study is to quantify the foot stress distribution in 3D during its quasi-static stand using a footprint into an imprinting material when knowing its mechanical properties. One foot of a female, having the mass of 65kg, was chosen for the FEM foot model construction. After obtaining her foot imprint to the dental imprinting material, its positive plaster cast was created, whose surface was possible to scan using stereophotogrammetry. The imprint surface digital model was prepared with the help of the Konica-Minolta Vivid 9i triangulation scanner. This procedure provides the measured object models in a high resolution. The resulting surface mesh of the foot imprint involved 9.600 nodes and 14.000 triangles, approximately, after reduction due to the FEM analysis. Simulation of foot imprint was solved as the 3D time dependent nonlinear mechanical problem in the ADINA software. The sum of vertical reactions calculated at the contact area nodes was 320.5 N, which corresponds to the mass of 32.67 kg. This value is in a good agreement with the subject half weight – the load of one foot during its quasi-static stand. The partial pressures resulting from this mathematical model match the real pressures on the interface of the foot and imprinting material quite closely. Principally, these simulations can be used to assess the contact pressures in practical cases, e.g., between a foot and its footwear.
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Pankova, B., T. Koudelka, K. Pavelka, M. Janura, and K. Jelen. "EXPLOITATION OF STEREOPHOTOGRAMMETRIC MEASUREMENT OF A FOOT IN ANALYSIS OF PLANTAR PRESSURE DISTRIBUTION." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences III-5 (June 6, 2016): 153–58. http://dx.doi.org/10.5194/isprs-annals-iii-5-153-2016.
Повний текст джерелаАнотація:
Stereophotogrammetry as a method for the surface scanning can be used to capture some properties of the human body parts. The objective of this study is to quantify the foot stress distribution in 3D during its quasi-static stand using a footprint into an imprinting material when knowing its mechanical properties. One foot of a female, having the mass of 65kg, was chosen for the FEM foot model construction. After obtaining her foot imprint to the dental imprinting material, its positive plaster cast was created, whose surface was possible to scan using stereophotogrammetry. The imprint surface digital model was prepared with the help of the Konica-Minolta Vivid 9i triangulation scanner. This procedure provides the measured object models in a high resolution. The resulting surface mesh of the foot imprint involved 9.600 nodes and 14.000 triangles, approximately, after reduction due to the FEM analysis. Simulation of foot imprint was solved as the 3D time dependent nonlinear mechanical problem in the ADINA software. The sum of vertical reactions calculated at the contact area nodes was 320.5 N, which corresponds to the mass of 32.67 kg. This value is in a good agreement with the subject half weight – the load of one foot during its quasi-static stand. The partial pressures resulting from this mathematical model match the real pressures on the interface of the foot and imprinting material quite closely. Principally, these simulations can be used to assess the contact pressures in practical cases, e.g., between a foot and its footwear.
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Guerrero, M. "The investigation of sediment processes in rivers by means of the Acoustic Doppler Profiler." Proceedings of the International Association of Hydrological Sciences 364 (September 16, 2014): 368–73. http://dx.doi.org/10.5194/piahs-364-368-2014.
Повний текст джерелаАнотація:
Abstract. The measurement of sediment processes at the scale of a river cross-section is desirable for the evaluation of many issues related to river hydro-morphodynamics, such as the calibration and validation of numerical models for predicting the climate change impacts on water resources and efforts of maintenance of the navigation channel and other hydraulic works. Suspended- and bed-load have traditionally been measured by cumbersome techniques that are difficult to apply in large rivers. The acoustics for the investigation of small-scale sedimentological processes gained acceptance in the marine community because of its ability to simultaneously profile sediment concentration and size distribution, non-intrusively, and with high temporal and spatial resolution. The application of these methods in true riverine case studies presents additional difficulties, mainly related to water depths and stream currents that limit sound propagation into water and challenge the instruments deployment, especially during floods. This article introduces the motivations for using the ADCP for sediment processes investigation other than for flow discharge measurement, summarizes the developed methods and indicates future desirable improvements. In addition, an application on the Po River in Italy is presented, focusing on the calibration of the existing software by means of ADCP recordings. The calibrated model will assist in planning the dredging activities to maintain the navigation channel and the intake of a pump station for irrigation that is periodically obstructed with a sandbar.
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Yu, Miao, and Chao Lu. "A New Optimized Method of Excitation Signal for Closed-Loop Identification of Power System Based on Ambient Signals." Applied Mechanics and Materials 157-158 (February 2012): 277–85. http://dx.doi.org/10.4028/www.scientific.net/amm.157-158.277.
Повний текст джерелаАнотація:
Excitation signal optimization is an important part in the power system identification based on ambient signals. An adaptive discrete Kalman filter method is proposed to select an optimal signal for closed-loop identification in this paper. This method is carried out through the use of the measurement innovation sequence as piecewise stationary process inside an estimation window. It also overcomes the shortcomings of relying on the correctness of the mathematical and statistical models excessively. The feature of random load changing in power system is fully considered in this method. Then under the energy constraints of input and output signals, this method can be used to solve the excitation signal which satisfies the performance of power system and the noise covariance estimation matrices are acquired. By using this method, the optimal identification model can be obtained. Simulation results show the effective performance of the proposed method. Compared with other methods, the quality of the closed-loop identification model based on ambient signals is improved by using the excitation signal optimal method proposed in this paper.
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Müller, Eric A., and Anna G. Stefanopoulou. "Analysis, Modeling, and Validation for the Thermal Dynamics of a Polymer Electrolyte Membrane Fuel Cell System." Journal of Fuel Cell Science and Technology 3, no. 2 (September 14, 2005): 99–110. http://dx.doi.org/10.1115/1.2173663.
Повний текст джерелаАнотація:
A control-oriented mathematical model of a polymer electrolyte membrane (PEM) fuel cell stack is developed and experimentally verified. The model predicts the bulk fuel cell transient temperature and voltage as a function of the current drawn and the inlet coolant conditions. The model enables thermal control synthesis and optimization and can be used for estimating the transient system performance. Unlike other existing thermal models, it includes the gas supply system, which is assumed to be capable of controlling perfectly the air and hydrogen flows. The fuel cell voltage is calculated quasistatically. Measurement data of a 1.25kW, 24-cell fuel cell stack with an integrated membrane-type humidification section is used to identify the system parameters and to validate the performance of the simulation model. The predicted thermal response is verified during typical variations in load, coolant flow, and coolant temperature. A first-law control volume analysis is performed to separate the relevant from the negligible contributions to the thermal dynamics and to determine the sensitivity of the energy balance to sensor errors and system parameter deviations.
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Buchhave, Preben, and Clara M. Velte. "A similarity scaling model for the axisymmetric turbulent jet based on first principles." Physics of Fluids 34, no. 9 (September 2022): 095102. http://dx.doi.org/10.1063/5.0102809.
Повний текст джерелаАнотація:
Similarity scaling, when it can be justified, is a powerful tool for predicting properties of fluid flows and reducing the computational load when using mathematical models. Numerous publications describe different applications of this method, using often different scaling laws with one or more scaling parameters. The justification for these laws is often based on some assumptions or references to experimental results. In this paper, we base the scaling law on basic physical principles of classical Newtonian physics (Galilei group) and derive some predictions that we apply to a simple model for the axisymmetric turbulent jet. In a companion paper, we compare these predictions to careful measurements on a free jet in the laboratory and evaluate how far our model predictions are borne out by the experimental results. We have succeeded in obtaining such high-measurement quality that we can compute both second- and third-order statistical functions even far downstream and far-off axis. We can already here reveal that we find very good agreement between a simple one-parameter geometric scaling law derived from the model and numerous first-order and higher-order statistical results computed from the experimental data.
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Monieta, Jan. "The use of thermography in the diagnosis of ship piston internal combustion engines." MATEC Web of Conferences 182 (2018): 01027. http://dx.doi.org/10.1051/matecconf/201818201027.
Повний текст джерелаАнотація:
The intensity of infrared radiation emitted by objects depends mainly on their temperature. One of the diagnostic signals may be the temperature field. In infrared thermography, this quantity is used as an indicator of the technical condition of marine objects. The article presents an overview of the use of infrared thermography for the diagnosis mainly of marine piston floating objects and various types of reciprocating internal combustion engines as well as examples of own research results. A general introduction to infrared thermography and common procedures for temperature measurement and non-destructive testing are presented. Experimental research was carried out both in laboratory conditions and in the operating conditions of sea-going vessels. Experimental studies consisted of the presentation of photographs of the same objects made in visible light and the use of infrared thermography. The same objects were also compared, but for different cylinders of the tested internal combustion engines as well as for the up state and fault state. The characteristics of the temperature values at selected points were taken depending on the engine load along with the approximation mathematical models of these dependencies.
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Šušnjar, Marijan, Zdravko Pandur, Marin Bačić, Kruno Lepoglavec, Hrvoje Nevečerel, and Hrvoje Kopseak. "Possibilities for the Development of an Electric Hybrid Skidder Based on Energy Consumption Measurement in Real Terrain Conditions." Forests 14, no. 1 (December 28, 2022): 58. http://dx.doi.org/10.3390/f14010058.
Повний текст джерелаАнотація:
Growing demand for forest machines that cost less to operate than current compared to traditional hydraulic and mechanical ones, along with regulatory pressures for lower emissions, is increasing manufacturers’ interest in developing electric and hybrid drives. While purely electric drives of forest machines meet a lot of bottlenecks (costs of the electric components, battery durability, duration of charging, access to the electrical grid, size of batteries that can ensure enough energy for 8 h working time), electric hybrid drives offer a favorable solution for the propulsion of forestry machinery in terms of lower fuel consumption and improved efficiency. Among all forest vehicles, specialized forest tractors (skidders), so far, have not been considered for forest vehicles with hybrid drive capabilities. A skidder is a forest-articulated self-propelled vehicle for pulling trees or parts of trees. In most countries in southern Europe, the use of skidders equipped with forest winches is the most common technique for timber extraction. The first goal of the research is to develop methods for measuring the energy consumption of skidders at different operating tasks and under different field conditions. Research was performed on the skidder Ecotrac 140V (from Croatian producer Hittner Ltd.) during timber extraction in mountainous terrains in Lika–Senj County. The skidder was equipped with a measuring device WIGO-E (Telematic Data collector) gateway with an integrated GPS system, which ensured data were collected from sensors and motor and stored in a computer via CANBUS and data transfer with GSM to Web platforms. Additionally, a fuel-flow meter was installed on the skidder. Data on fuel consumption (mL), position (traveling route), detection of winch work, engine rpm (min−1), engine torque (% of max), throttle position (%), and engine temperature were measured with a sampling frequency of 5 s. Furthermore, skidder load volumes per cycles and slopes of tractor paths were constantly measured. The paper shows the skidder’s energy consumption per day, work cycle, and individual work procedure with regard to the size of the load, the slope of the tractor path, and the direction of movement based on overlapping and merging all measurement data. Using mathematical and simulation models of the drive with defined operating cycles obtained by measurement, the possibilities of the hybrid drive and the dimensions of the elements of the hybrid drive (internal combustion engine, electric motor, batteries, control unit) were determined and are presented in this paper.
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Yang, Mengying, Dingding Xiang, Song Wang, and Weiqiang Liu. "The Radial Bulging and Axial Strains of Intervertebral Discs during Creep Obtained with the 3D-DIC System." Biomolecules 12, no. 8 (August 10, 2022): 1097. http://dx.doi.org/10.3390/biom12081097.
Повний текст джерелаАнотація:
Creep-associated changes in disc bulging and axial strains are essential for the research and development of mechano-bionic biomaterials and have been assessed in various ways in ex vivo creep studies. Nonetheless, the reported methods for measurement were limited by location inaccuracy, a lack of synchronousness, and destructiveness. To this end, this study focuses on the accurate, synchronous, and noninvasive assessment of bugling and strains using the 3D digital image correlation (3D-DIC) system and the impact of creep on them. After a preload of 30 min, the porcine cervical discs were loaded with different loads for 4 h of creep. Axial strains and lateral bulging of three locations on the discs were synchronously measured. The three-parameter solid model and the newly proposed horizontal asymptote models were used to fit the acquired data. The results showed that the load application reduced disc strains by 6.39% under 300 N, 11.28% under 400 N, and 12.59% under 500 N. Meanwhile, the largest protrusion occurred in the middle of discs with a bugling of 1.50 mm, 1.67 mm, and 1.87 mm. Comparison of the peer results showed that the 3D-DIC system could be used in ex vivo biomechanical studies with reliability and had potential in the assessment of the mechanical behavior of novel biomaterials. The phenomenon of the largest middle protrusion enlightened further the strength of spinal implants in this area. The mathematical characterizations of bulging and strains under different loads yielded various model parameters, which are prerequisites for developing implanted biomaterials.
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Salinari, Serenella, Alessandro Bertuzzi, Melania Manco та Geltrude Mingrone. "NEFA-glucose comodulation model of β-cell insulin secretion in 24-h multiple-meal test". American Journal of Physiology-Endocrinology and Metabolism 292, № 6 (червень 2007): E1890—E1898. http://dx.doi.org/10.1152/ajpendo.00563.2006.
Повний текст джерелаАнотація:
There is experimental evidence that a source of fatty acids (FAs) that is either exogenous or endogenous is necessary to support normal insulin secretion. Therefore, FAs comodulate the glucose-induced pancreatic insulin secretion. To assess the role of FAs, 16 morbidly obese nondiabetic patients and 6 healthy volunteers were studied. The controls and the obese subjects, before and after diet-induced weight loss, spent 24 h in a calorimetric chamber, where they consumed standardized meals. Hourly blood samples were drawn from a central venous catheter for the measurement of glucose, C-peptide, and nonesterified fatty acid (NEFA) concentrations. Insulin sensitivity was measured (as the M value) by euglycemic hyperinsulinemic clamp. In the present study, we propose a mathematical model in which insulin secretion rate (ISR) is expressed as a function of both plasma glucose and NEFA concentrations. Model parameters, obtained by fitting the individual experimental data of plasma C-peptide concentration, gave an estimated ISR comparable with that obtained by the deconvolution method. To evaluate the performance of the model in an experimental condition in which incretin effect was minimized, previous data on insulin secretion following a butter load and subsequent hyperglycemic clamp were reanalyzed. This model of nutrient-stimulated insulin secretion is the first attempt to represent in a simple way the interaction between glucose and NEFA in the regulation of insulin secretion in the β-cell and explains, at least in part, the “potentiation factor” used in previous models to account for other control factors different from glucose after either an intravenous infusion of glucose or a mixed meal.
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Cozzi, Mauro, Livio Ruvo, Paolo Scaglioni, and Anna Maria Lyne. "Core-Data Preprocessing To Improve Permeability-Log Estimation." SPE Reservoir Evaluation & Engineering 10, no. 05 (October 1, 2007): 563–70. http://dx.doi.org/10.2118/100748-pa.
Повний текст джерелаАнотація:
Summary Two techniques of preprocessing data from core plugs have been investigated to enhance the quality of synthetic permeability estimation from conventional logs by use of artificial neural networks (ANNs). A first technique consists of "cleaning" the core-plug data set by removing the measurements deemed log-incompatible (i.e., those from plugs corresponding to log measurements affected by shoulder-bed effect or layers with thickness below the vertical log resolution). The second technique relies on building high-resolution digital models of cored intervals by use of a process-oriented-modeling (POM) approach—the core model is populated with permeability values from core plugs and then upscaled to a log-equivalent support volume. Synthetic permeability curves estimated with these techniques have been compared to synthetic permeability curves estimated without core-data preprocessing and to permeability estimated directly from core plugs and properly calibrated permeability curves from a nuclear magnetic resonance (NMR) log tool in a turbidite reservoir, the ground truth value being represented by actual dynamic data. Results highlight that core-to-log scale effects play a major role in the permeability estimation from conventional logs and show that the proposed preprocessing techniques can be effective in improving permeability prediction, because they significantly reduce cross-scaling problems related to the differences in support volumes. Strengths and weaknesses of the two preprocessing approaches also have been compared. The first technique is faster, but its application is strongly constrained by the statistical and geological representativeness of the selected data set. This is because some lithologies go under represented so as to question the use of estimation tools like ANNs. Conversely, the POM preprocessing technique is more time-consuming and needs detailed core descriptions, but has the great advantage of supplying—starting from core data only—a reliable permeability curve that retains its validity at the log scale. Introduction Permeability prediction in hydrocarbon reservoirs is probably the most challenging issue that geologists, petrophysicists, and reservoir engineers have to deal with. In particular, the availability of permeability curves in a large number of wells is one of the most desired targets in a reservoir-characterization study. In recent years, logging techniques such as NMR have been developed that allow permeability curves to be generated along reservoir intervals. Nevertheless, the availability of NMR logs is not the rule: In the majority of the wells, especially those from older fields, the only permeability measurement available comes from plugs sparsely sampled from bottomhole cores. On the other hand, bottomhole cores are usually available only in a few reservoir intervals and/or wells, whereas conventional log recordings (natural gamma ray, density, and neutron) are available from nearly every well. Attempts to correlate core permeability to porosity and/or other conventional logs using mathematical/statistical tools date back to the early 1960s. Since then, regression analysis has been the most widely used approach for permeability prediction: This approach assumes that the permeability vs. porosity—or, alternatively, vs. conventional logs—functional relationships can be known in advance. As a matter of fact, functional relationships are unknown.
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Yilmaz, Levent. "Applications in New River-meander Model." Journal of Geographical Research 3, no. 1 (July 2, 2020). http://dx.doi.org/10.30564/jgr.v3i1.1896.
Повний текст джерелаАнотація:
If the sediment transport behaves as bed-load, the sediment surface at meandering channel will deform into transverse waves. This investigation isa new model for prediction of river-meander models in nature. The aim ofthis research is to give a precise method whose bed forms can have a variety of scales ranging from ripples through small dunes to fully developeddunes or sandwaves. Its mathematical model will be investigated.