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1
Shaazizov, farrukh shoakbarovich, and oybek farhodjon ugli Vokhidov. "ASSESSMENT OF DAMAGE DURING THE FORMATION AND PASSAGE OF MUDFLOWS IN THE TASHKENT REGION." Journal of agro processing 4, no. 5 (2022): 4. https://doi.org/10.5281/zenodo.7340588.
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Mountainous and largely foothill areas of the Republic of Uzbekistan are mudflow hazardous. In Tashkent region, there are two mudflow river basins (dangerous in relation to the manifestation of mudflows): the Chirchik river basin and the Akhangaran river basin. Based on the results of long-term observations of the Uzhydromet service, a digital map of the mudflow hazard in the Tashkent region for a century was compiled. The method for determining the damage from the action of mudflows on a specific object consists in determining the equivalent mudflow pressure according to its initial parameters. According to the methodology for assessing damage in the event of a natural emergency, the main parameters of the damaging factors were determined during the passage of a mudflow in the event of intense rainfall. The calculations were performed for two scenarios: 1) with dangerous rainfall with an intensity of 30 mm per day; 2) in case of especially dangerous rainfall with an intensity of 60 mm per day. Based on the calculations performed, the amount of damage to the national economy of the Tashkent region was determined during the passage of a mudflow caused by intense rainfall.
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Shaazizov, Farrukh. "Assessment of damage during the formation and passage of mudflows in the Tashkent region." E3S Web of Conferences 264 (2021): 03042. http://dx.doi.org/10.1051/e3sconf/202126403042.
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Mountainous and largely foothill areas of the Republic of Uzbekistan are mudflow hazardous. In the Tashkent region, there are two mudflow river basins (dangerous concerning the manifestation of mudflows): the Chirchik river basin and the Akhangaran river basin. Based on the results of long-term observations of the Uzhydromet service, a digital map of the mudflow hazard in the Tashkent region for a century was compiled. The method for determining the damage from the action of mudflows on a specific object consists of determining the equivalent mudflow pressure according to its initial parameters. According to the methodology for assessing damage in the event of a natural emergency, the main parameters of the damaging factors were determined during the passage of a mudflow in the event of intense rainfall. The calculations were performed for two scenarios: 1) with dangerous rainfall with an intensity of 30 mm per day; 2) in case of especially dangerous rainfall with an intensity of 60 mm per day. Based on the calculations performed, the amount of damage to the national economy of the Tashkent region was determined during the passage of a mudflow caused by intense rainfall.
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Markarian, A. A., E. Yu Kudelya, I. D. Makitruk, N. Yu Pilyavskaya, D. A. Virki, and A. V. Bulatov. "Assessment of the Equivalence of Methods for the Determination of the Vapor Pressure of Oil and Oil Products." Measurement Standards. Reference Materials 19, no. 5 (2024): 143–53. http://dx.doi.org/10.20915/2077-1177-2023-19-5-143-153.
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Current regulatory documents in Russia establish the need for testing laboratories to determine such parameters as saturated vapor pressure using the Reid method, air saturated vapor pressure, total vapor pressure of crude oil. In analytical practice, appropriate reference materials are used for measurement quality control, method validation, metrological traceability establishment, and other purposes. In addition, the calculation of various vapor pressure equivalents using correlation equations (DVPE – dry vapor pressure equivalent, RVPE – Reid vapor pressure equivalent, etc.) is regulated by appropriate methods for determining vapor pressure. Vapor pressure is a method-dependent parameter; so many producers of reference materials use interlaboratory experiment as a way to establish a certified value. Thus, when conducting an interlaboratory experiment in the process of certification of reference materials, it was revealed that laboratories can incorrectly interpret the obtained experimental data – consider values of the air saturated vapor pressure, total vapor pressure and even calculated vapor pressure equivalents as the Reid vapor pressure. To solve this problem, the authors of this work set the goal of assessing the equivalence of methods for determining the vapor pressure of oil and oil products used in testing laboratories in order to identify the key characteristics of the stated methods and assess their equivalence. The article discusses methods the vapor pressure determination using an automatic vacuum chamber and a Reid bomb. Various matrices of reference materials (hydrocarbons, gasoline, commercial oil, gas condensate) were investigated, and the calculated vapor pressure equivalents were obtained and compared. It was shown that the air saturated vapor pressure, dry vapor pressure equivalent, Reid vapor pressure equivalent, and total vapor pressure cannot be equated to the saturated vapor pressure values determined by the Reid method. A comparative assessment of methods for determining the vapor pressure of oil and oil products used in testing laboratories can be of assistance to developers of regulatory documents for oil, gas condensate, and motor gasoline, revealing the need to separate the requirements for vapor pressure parameters of the considered objects of analysis and providing empirical material.
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Hagen, Anette B., Bård Nyhus, Michael R. Gerhardt, et al. "Experimental determination of equivalent hydrogen gas pressure from electrochemical hydrogen charging." International Journal of Hydrogen Energy 82 (September 2024): 1146–56. http://dx.doi.org/10.1016/j.ijhydene.2024.02.117.
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Jung, Dong Soo, Hyoung Eui Kim, Sung Hun Kim, and E. Sok Kang. "Development of Accelerated Life Test Method of Hydraulic Pump." Key Engineering Materials 326-328 (December 2006): 1861–64. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.1861.
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This paper proposes a new accelerated life test method of hydraulic pump used in vehicles, which have multiple alternating loads. For determination of life time of hydraulic pump for given field conditions with respect to duty cycle, the equivalent load and speed of this unit has to be determined. Equivalent load and speed can be calculated from the given duty cycle using the predominant theory for cumulative fatigue damage. Finally, we can perform accelerated life test on hydraulic pump by determination of test pressure and speed from calculated equivalent cumulative damage per working cycle and weighted average speed.
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Wang, Jian, Tao Wei, Zhuoyang Song, Rui Chen, and Qiu He. "Determination of the Equivalent Length for Evaluating Local Head Losses in Drip Irrigation Laterals." Applied Engineering in Agriculture 38, no. 1 (2022): 49–59. http://dx.doi.org/10.13031/aea.14735.
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HighlightsA hydraulic model was used to determine the value of the equivalent length for evaluating local emitter head losses in drip laterals.Dimensional analysis was used to develop an equation for predicting the equivalent length.The effects of the design variables on the equivalent length were investigated.The accuracy of the equation was validated by a previous experiment and an alternative hydraulic model.Abstract. The equivalent length is widely used in current hydraulic models to estimate local emitter head losses for the analysis and design of drip irrigation laterals. The accurate evaluation of the equivalent length is therefore required in the lateral design procedure. In this study, a finite element model was used to develop an equation to predict the equivalent length. Eight design variables were selected, and 32 lateral cases were generated using the orthogonal design. The total local head loss in the 32 laterals were firstly calculated using the local head loss coefficient multiplied by the kinetic head. The solutions were considered as exact values and being equivalent to friction head losses, and the equivalent length was computed using the Darcy-Weisbach equation. Dimensional analysis and regression procedures were then used to obtain the prediction equation related to the selected variables. The results show that the converted equivalent lengths accurately estimated the local head losses in the 32 laterals. The local head loss coefficient was the most important factor for the equivalent length, followed by the lateral diameter. The effects of the lateral inlet pressure head, flow exponent, nominal flow rate of emitter, number of emitter, emitter spacing and lateral slope were not significant. Two models were developed to predict the equivalent length, and to calculated the total local head losses. The results demonstrated satisfactory agreement with the measured value available in a previous experimental study, with RMSE = 0.202 and 0.162 m for the full and simplified model, respectively. The percent error between the measured and calculated total head losses using simplified model was from -16.5% to 14.8%, and the Camargo and Sentelhas coefficient c was higher than 0.98. The equations were therefore capable for evaluating the local head loss in the hydraulic design of drip irrigation laterals. Keywords: Dimensional analysis, Finite element method, Hydraulic design, Pressure head, Uniformity.
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Lazarescu, Lucian, Ioan Pavel Nicodim, Dan Sorin Comsa, and Dorel Banabic. "A Procedure for the Evaluation of Flow Stress of Sheet Metal by Hydraulic Bulge Test Using Elliptical Dies." Key Engineering Materials 504-506 (February 2012): 107–12. http://dx.doi.org/10.4028/www.scientific.net/kem.504-506.107.
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The paper describes a new experimental procedure for the determination of the curves relating the equivalent stress and equivalent strain of sheet metals by means of the hydraulic bulge tests through elliptical dies. The procedure is based on an analytical model of the bulging process and involves the measurement of only two parameters (pressure acting on the surface of the specimen and polar deflection).
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Zhao, Jie, Zhan Qi Guo, and Gai Fei Peng. "Vapor Pressure Modeling for Fire Damage Assessment of HPC." Key Engineering Materials 417-418 (October 2009): 509–12. http://dx.doi.org/10.4028/www.scientific.net/kem.417-418.509.
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High-performance concrete will undergo severe damage under fire conditions. It is well known that vapor pressure induced by high temperatures plays an important role in the damaging process. This paper presents a method of vapor pressure modeling, called equivalent expansion method, which can be implemented in FEM analysis. The modeling procedure consists of two parts, i.e. vapor pressure determination and vapor pressure modeling incorporated in FEM analysis. In order to make analysis more accurate, steam table is employed instead of ideal gas equation.
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Lazarević, Miloš, Bogdan Nedić, Jovica Bogdanov, and Stefan Đurić. "Determination of the critical distance in the procedure of explosive welding." Vojnotehnicki glasnik 68, no. 4 (2020): 823–44. http://dx.doi.org/10.5937/vojtehg68-26683.
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Introduction/purpose: When performing the explosive welding procedure, for the safety of workers, it is necessary to take into account the minimum distance between the workers and the place of explosion at the time of explosion. Negligence can cause temporary hearing loss, rupture of the eardrum and in some cases even the death of workers. The aim of this paper is to determine the critical distance based on the mass of explosive charge required for explosive welding, provided that the limit pressure is 6.9 kPa in the case of temporary hearing loss and 35 kPa in the case of eardrum rupture. This paper does not take into account other effects of the explosion than those caused by the shock wave. Methods: Depending on the type of explosion, the equivalent explosive mass was calculated. Based on the equivalent explosive mass and the limit pressure, the minimum distances were calculated using the Sadovsky and Kingery-Bulmash equations. Results: The corresponding tables show the results of the calculation of the critical distance of workers from the place of the explosion when there may be temporary hearing loss or rupture of the eardrum. The calculated value of the critical explosion distance by the Kingery-Bulmash method, under the condition of the maximum pressure for temporary hearing loss, is 5.62% lower than the distance value obtained by the Sadovsky method while the value of the critical explosion distance calculated by the Kingery-Bulmash method, under the condition of the maximum pressure for eardrum rupture, is 7.83% lower than the value obtained by the Sadovsky method. Conclusion: The results of the calculation showed that the critical distance from the explosion can be successfully calculated and that the obtained values have small differences depending on the applied calculation method.
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Seshadri, R., та H. Indermohan. "Lower Bound Limit Load Determination: The mβ-Multiplier Method". Journal of Pressure Vessel Technology 126, № 2 (2004): 237–40. http://dx.doi.org/10.1115/1.1688780.
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The existing lower bound limit load determination methods, that are based on linear elastic analysis such as the classical and mα-multiplier methods, have a dependence on the maximum equivalent stress. These methods are therefore sensitive to localized plastic action, which occurs in components with thin or slender construction, or those containing notches and cracks. Sensitivity manifests itself as relatively poor lower bounds during the initial elastic iterations of the elastic modulus adjustment procedures, or oscillatory behavior of the multiplier during successive elastic iterations leading to limited accuracy. The mβ-multiplier method proposed in this paper starts out with Mura’s inequality that relates the upper bound to the exact multiplier by making use of the “integral mean of yield.” The formulation relies on a “reference parameter” that is obtained from considering a distribution of stress rather than a single maximum equivalent stress. As a result, good limit load estimates have been obtained for several pressure component configurations.
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GHISTA, DHANJOO N., LI LIU, LEOK POH CHUA, LIANG ZHONG, RU SAN TAN, and YONG SENG TAN. "MECHANISM OF LEFT VENTRICULAR PRESSURE INCREASE DURING ISOVOLUMIC CONTRACTION, AND DETERMINATION OF ITS EQUIVALENT MYOCARDIAL FIBERS ORIENTATION." Journal of Mechanics in Medicine and Biology 09, no. 02 (2009): 177–98. http://dx.doi.org/10.1142/s0219519409002924.
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The left ventricle (LV) is modelled as a fluid-filled, thick-walled finite-elasticity cylindrical shell, subject to internal pressure increase during isovolumic contraction. Our objective is to elucidate that the tremendous internal pressure build-up during isovolumic contraction is caused by stress development in the spirally-wound myocardial fibers due to their contraction. The LV model data consists of LV chamber pressure, LV dynamic geometry and LV twist angle. In our analysis, the LV chamber pressure increase and LV (radial, longitudinal, and twist) deformations are formatted to be caused by the contractile stresses in the LV myocardial fibers (based on the hyper-elastic constitutive property of the LV myocardial wall, expressed in terms of the strain energy density function). The LV wall stresses are expressed in terms of the strain energy density function, and hence in terms of the measured LV wall strains and the material parameters. Then, by satisfying the stress boundary conditions, from the measured data on LV deformation state and LV pressure, we first determine the LV wall's constitutive properties, and then the instantaneous stress state in the LV. The stress generated in the LV cylindrical model is equivalent to the development of active compression force and torsion within the model, as a mechanism for the high intra-LV cavity pressure build-up during isovolumic contraction. We in turn adopt (i) the principal compressive stress to be the stresses developed in the myocardial fibers (by their contraction), and (ii) the principal stress trajectory to correspond to the orientation of the myocardial fibers. The results show that the myocardial fiber orientation changes during the isovolumic phase, as the LV contracts. Hence, an important determinant of our analysis is the orientation of the myocardial fibers. Conversely, it can be said that the fibers are so optimally oriented, that their contraction causes LV deformation to in turn cause the appropriate increase in intra-LV pressure. Another important outcome of our analysis is the determination of the "LV torque vs twist angle" relationship, which has the potential to be employed as an index of contractility.
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de Freitas, Elis Marina, Thayne Nárgyle Botelho Vital, Gabriel Fernandes Costa Guimarães, Fernando Augusto da Silveira, Carlos Nick Gomes, and Fernando França da Cunha. "Determination of the Permanent Wilting Point of Physalis peruviana L." Horticulturae 9, no. 8 (2023): 873. http://dx.doi.org/10.3390/horticulturae9080873.
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The soil–water potential limit, or permanent wilting point (PWP), of Physalis peruviana L. is not known. Thus, determining the PWP of P. peruviana in different soils is essential to plan crops and manage irrigation in order to optimize the use of water and electricity. The objective of this study was to determine the PWP for P. peruviana in sandy and sandy clay loam soils. In a greenhouse, P. peruviana plants were grown in pots with different types of soil and maintained at 80% of field capacity. At intervals of 10 days, the irrigation of three pots was stopped, and when the plants wilted, they were transferred to a dark chamber without a vapor pressure deficit to verify if they would return to turgidity. When turgidity was not recovered, the PWP was considered, and the soil matric potential was determined by the water retention curve method. In sandy soil, P. peruviana wilted, on average, 1.7 days faster than in sandy clay loam soil. Regardless of the soil, matric potential equivalent to PWP decreased throughout the P. peruviana crop cycle. For sandy soil, the matric potential equivalent to PWP of P. peruviana ranges from −180 kPa (equivalent to 12% of the estimated value with a moisture release curve) to −2266 kPa (151% of the estimated value). In sandy clay loam soil, this matric potential ranges from −665 kPa (44% of the estimated value) to −1611 kPa (107% of the estimated value). The results contribute to water management and calculation of available water for P. peruviana; however, different soil textures do not have a single matric potential equivalent to PWP.
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Šperling, Petr, Rudolf Hela, Adam Hubáček, Tereza Stará, and Richard Dvořák. "Possibilities of K-Value Determination for Active Admixtures with Respect to Durability." Materials 18, no. 10 (2025): 2227. https://doi.org/10.3390/ma18102227.
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This paper discusses the possibility of determining k-values for active admixtures concerning durability factors such as the depth of penetration of water under pressure and the depth of carbonation of cement mortars with fly ash. The k-value considers the use of active admixtures in concrete when calculating the water/cement ratio and the equivalent amount of binder. Currently, only the effect of the active admixture on the compressive strength of concrete and cement mortars is considered when determining the k-value, but not the effect of the active admixture on durability. To account for the influence of durability factors on the determination of the k-value, the mathematical functions of the property, dependent on the water/cement ratio and the age of the cement mortar, were constructed using regression analysis. From the determined functions, it was then possible to use an optimisation problem to determine the k-value so the difference between the actual measurement and calculated depth of pressure water seepage or carbonation was as small as possible. A high coefficient of determination of 0.9855 was achieved for the pressure water seepage depth function, but the coefficient of determination for the carbonation depth was lower.
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Li, Hongjun, Shichun Chi, Gao Lin, and Hong Zhong. "A modified approach for determination of nonlinear properties in seismic response analyses for 200 m high core rock-fill dams." Canadian Geotechnical Journal 45, no. 8 (2008): 1064–72. http://dx.doi.org/10.1139/t08-045.
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Equivalent linear analyses are widely used for estimation of site response and safety status of rock-fill dams subjected to strong earthquakes. However, the average normalized curves incorporated in the equivalent-linear iterative process cannot precisely depict the variations of dynamic parameters with shearing strain for one type of soil material under a wide range of confining pressures. Thus, a modified approach for the determination of nonlinear properties for soil elements confined under a broad range of effective pressures in site response analyses for high rock-fill dams (>200 m) is proposed. In this approach, the normalized confining-pressure-interpolating curves (CPI curves) of each soil element under different effective stress are obtained by linearly interpolating or extrapolating by its in situ stress. By comparing the results obtained by equivalent linear analyses incorporating the average curves and the CPI curves, respectively, the impact of utilizing the recommended curves when determining nonlinear soil properties on site response analyses of high rock-fill dams (>200 m) is discussed. It is shown that the refinement in the determination of nonlinear properties during site response can be utilized in the near future by incorporating the results of this study in practice.
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Dreier, Christian, Xenia Vogt, Wolfgang Schröder, and Michael Vorländer. "Acoustic source characterization of simulated subsonic jet noise using spherical harmonics." Journal of the Acoustical Society of America 154, no. 1 (2023): 167–78. http://dx.doi.org/10.1121/10.0020065.
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As subsonic jets remain one of the major contributions to aircraft noise emissions, near-field flow simulations should be included in aircraft design at an early stage using quantitatively predicted sound pressure levels and the time-domain signal properties of the noise data. In this regard, the interface from the near-field data to the far-field radiation—under consideration of acoustic reflections from objects such as fuselage and wings—remains as bottleneck. This study presents the computation of a spherical equivalent source model of jet noise with minimal complexity by means of spherical harmonic (SH) coefficients. Using spherical Hankel extrapolation of sound pressure data from virtual, concentrical microphone arrays, the results of the determination for the radius, in which all acoustic sources of a flow field are confined, indicate the source radius around the end of the potential core to be equivalent to five times the nozzle diameter. The result of the SH transform shows the dominant energy contribution to be related to nine elementary sources. The resulting equivalent source model of jet noise provides a convenient format for further use in large-scale computational fluid dynamics simulations.
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Bozca, Mehmet. "EFFECTS OF DESIGN PARAMETERS ON STATIC EQUIVALENT STRESS OF RADIAL ROLLING BEARINGS." Acta Polytechnica 61, no. 1 (2021): 163–73. http://dx.doi.org/10.14311/ap.2021.61.0163.
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The aim of this study is to theoretically investigate the effects of design parameters on the static equivalent stress of radial rolling bearings, such as the point contact case for ball bearings and line contact case for roller bearings. The contact pressure, contact area and von Misses stress of bearings are calculated based on geometrical parameters, material parameters and loading parameters by using the developed MATLAB program. To achieve this aim, both the maximum contact pressure pmax and Von Mises effective stress σVM are simulated with respect to design parameters such as varying ball and roller element diameters and varying ball and roller element elasticity modulus. For the point contact case and line contact case, it was concluded that increasing the diameter of ball and roller elements results in reducing the maximum contact pressure pmax Furthermore, increasing the elasticity modulus of the ball and roller elements results in increasing the maximum contact pressure σVM. Furthermore, increasing the elasticity modulus of the ball and roller element results in increasing the maximum contact pressure pmax and Von Mises effective stress σVM because of the decrease of contact area A. The determination of the diameter of the ball and roller elements and the selection of material are crucial and play an effective role during the design process. Therefore, bearing designers and manufacturers should make the bearing geometrical dimensions as large as possible and bearing material as elastic as possible. Furthermore, the stress-based static failure theory can also be used instead of the standard static load carrying capacity calculation. Moreover, Von Mises stress theory is also compatible with the finite element method.
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V.K, Sveshnikov, Bazarkin A.F, and Kurenschikov A.V. "Calculation of Resonant Radiation Power of a Direct Sodium Lamp With Low Pressure." International Journal of Engineering & Technology 7, no. 3.19 (2018): 92. http://dx.doi.org/10.14419/ijet.v7i3.19.16993.
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They consider the calculation technique for the resonance radiation power of a direct low-pressure sodium lamp with a sickle-shaped discharge tube cross-section. The calculation of the sodium discharge radiation power is difficult in such a tube, as compared with the calculation in a cylindrical shape tube. The dependence of the relative output of sodium discharge resonant radiation occurring in equivalent discharge tubes in the form of a parallelepiped and a cylinder is based on the involvement of the theory by M. Cayless. The obtained results were used to determine the power of DNaO-85M lamp resonant radiation. They presented the scheme of the device to study the influence of the tube geometry on sodium discharge power. It is shown that the power of the resonance radiation generated by an equivalent discharge will be the greater, the larger the cross section of the discharge tube. The discrepancy between the calculated and the experimental data for resonant radiation power determination in a crescent-shaped tube is less than 4%.
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Ruth, P. J. van, R. R. Hillis, and R. E. Swarbrick. "DETECTING OVERPRESSURE USING POROSITY-BASED TECHNIQUES IN THE CARNARVON BASIN, AUSTRALIA." APPEA Journal 42, no. 1 (2002): 559. http://dx.doi.org/10.1071/aj01032.
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Overpressure has been encountered in many wells drilled in the Carnarvon Basin. Sonic logs are used to estimate pore pressure in shales in the Carnarvon Basin using the Eaton and equivalent depth methods of estimating pore pressure from velocity data with reference to a normal compaction trend. The crux of pore pressure estimation from the sonic log lies in the determination of the normal compaction trend, i.e. the acoustic travel time (Δt)/depth (z) trend for normally pressured sediments. The normal compaction trend for shales in the Carnarvon Basin was established by fitting an Athy-type exponential relationship to edited sonic log data, and is: Δt = 225 + 391exp(-0.00103z) Vertical stress estimates are also needed for the Eaton and equivalent depth methods used herein. A vertical stress (σv) relationship was obtained by fitting a regression line to vertical stress estimates from the density log, and is: σv = 0.0131 z1.0642 The Eaton and equivalent depth methods yield similar pressure estimates. However, the equivalent depth method can only be applied over a limited range of acoustic travel times, a limitation that does not apply to the Eaton method. The pressure estimates from the Eaton method were compared to pressures measured by direct pressure tests in adjacent permeable units. There is a good correlation between Eaton and test pressures in normally pressured intervals in three wells and overpressured intervals in two wells. Eaton pressure estimates underestimate overpressured direct pressure measurements in four wells by up to 13 MPa. This is consistent with overpressure being generated (at least in part) by a fluid expansion mechanism or lateral transfer of overpressure. The Eaton pressures in one well are, on average, 11 MPa lower than hydrostatic pore pressure recorded in direct pressure measurements below the Muderong Shale. The sediments in this well appear to be overcompacted due to exhumation. Mud weights can be used as a proxy for pore pressure in shales where direct pressure measurements are not available in the adjacent sandstones. The Eaton pressure estimates are consistent with mud weight in the Gearle Siltstone and Muderong Shale in 4 of the 8 wells studied. The Eaton pressures are on average 10 Mpa in excess of mud weight in the Muderong Shale and Gearle Siltstone in three wells. It is unclear whether the predicted Eaton pressures in these three wells accurately reflect pore pressure (i.e. the mud weights do not accurately reflect pore pressure), or whether they are influenced by changes in shale mineralogy (because the gamma ray filter does not differentiate between shale mineralogy).
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Ma, Li, Lu Ju He, and Hai Bo Wang. "Study on Thermal Boundary Condition of Manufacture Process for Composite Pressure Vessel." Key Engineering Materials 474-476 (April 2011): 915–18. http://dx.doi.org/10.4028/www.scientific.net/kem.474-476.915.
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The heat convection was the main heat exchange in the autoclave by which composite pressure vessel was cured. To determine the heat convection coefficient, the combination of theoretical calculation and temperature test is absolutely necessary. In the theoretical calculation, the determination of the heat convection coefficient is considered as an inversion problem of thermal conduction. By adjusting convection coefficient value in the finite element calculation, optimization method was employed to obtain a good agreement between calculated temperature and measured temperature. In the temperature test, the metallic liner of pressure vessel was used as test component to record temperature data which was compared with the calculated temperature. The results present the equivalent thermal boundary condition for the simulation of curing process of pressure vessel.
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Quin, S., and G. E. O. Widera. "Use of Stress-Strength Model in Determination of Safety Factor for Pressure Vessel Design." Journal of Pressure Vessel Technology 118, no. 1 (1996): 27–32. http://dx.doi.org/10.1115/1.2842158.
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In pressure vessel design, the values of safety factor are still determined on the basis of engineering experience. Thus, they cannot properly reflect the influence of the consequences of failure and the variabilities in stress and strength. As a result, designsare often excessively conservative, while on the other hand, the possibility of failure still exists. Two approaches for determining the value of the safety factor, which are based on reliability analysis, are presented in this paper. As a result of a comparison, one approach based on a stress-strength model is found to be appropriate for pressure vessel design practice. By transforming the interference parts of the distributions of stress and strength into equivalent normal distributions, the approach allows stress and strength to have arbitrary distributions. Three examples, one in which a vessel is subjected to internal pressure, one in which a tall vessel is subjected to combined loads, and one in which a vessel is subjected to external pressure, are given in the paper. From threexamples, the principles for determining target reliability and the factors affecting the safety factor are discussed. It is concluded that by using the approach presented in this paper for pressure vessel design, different consequences of failure as well as variabilities in stress and strength can be taken into account. The approach yields a value for the safety factor that leads to a design which will be safer and yet more economical.
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Wang, Xiaoming, Kefei Zhang, Suqin Wu, Changyong He, Yingyan Cheng, and Xingxing Li. "Determination of zenith hydrostatic delay and its impact on GNSS-derived integrated water vapor." Atmospheric Measurement Techniques 10, no. 8 (2017): 2807–20. http://dx.doi.org/10.5194/amt-10-2807-2017.
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Abstract. Surface pressure is a necessary meteorological variable for the accurate determination of integrated water vapor (IWV) using Global Navigation Satellite System (GNSS). The lack of pressure observations is a big issue for the conversion of historical GNSS observations, which is a relatively new area of GNSS applications in climatology. Hence the use of the surface pressure derived from either a blind model (e.g., Global Pressure and Temperature 2 wet, GPT2w) or a global atmospheric reanalysis (e.g., ERA-Interim) becomes an important alternative solution. In this study, pressure derived from these two methods is compared against the pressure observed at 108 global GNSS stations at four epochs (00:00, 06:00, 12:00 and 18:00 UTC) each day for the period 2000–2013. Results show that a good accuracy is achieved from the GPT2w-derived pressure in the latitude band between −30 and 30° and the average value of 6 h root-mean-square errors (RMSEs) across all the stations in this region is 2.5 hPa. Correspondingly, an error of 5.8 mm and 0.9 kg m−2 in its resultant zenith hydrostatic delay (ZHD) and IWV is expected. However, for the stations located in the mid-latitude bands between −30 and −60° and between 30 and 60°, the mean value of the RMSEs is 7.3 hPa, and for the stations located in the high-latitude bands from −60 to −90° and from 60 to 90°, the mean value of the RMSEs is 9.9 hPa. The mean of the RMSEs of the ERA-Interim-derived pressure across at the selected 100 stations is 0.9 hPa, which will lead to an equivalent error of 2.1 mm and 0.3 kg m−2 in the ZHD and IWV, respectively, determined from this ERA-Interim-derived pressure. Results also show that the monthly IWV determined using pressure from ERA-Interim has a good accuracy − with a relative error of better than 3 % on a global scale; thus, the monthly IWV resulting from ERA-Interim-derived pressure has the potential to be used for climate studies, whilst the monthly IWV resulting from GPT2w-derived pressure has a relative error of 6.7 % in the mid-latitude regions and even reaches 20.8 % in the high-latitude regions. The comparison between GPT2w and seasonal models of pressure–ZHD derived from ERA-Interim and pressure observations indicates that GPT2w captures the seasonal variations in pressure–ZHD very well.
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Stirnemann, A., J. Eberl, U. Bolleter, and S. Pace. "Experimental Determination of the Dynamic Transfer Matrix for a Pump." Journal of Fluids Engineering 109, no. 3 (1987): 218–25. http://dx.doi.org/10.1115/1.3242651.
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Dynamic instability in pumping systems can be the cause of a wide variety of difficulties. Analytical investigations of the dynamic behavior of such systems depend on the proper mathematical model of the dynamic performance of the pump. This paper is concerned with the experimental means and analysis procedures for obtaining the transfer matrix representing the pump as a four-pole element. Direct measurement of the pulsating flow is omitted in favor of an indirect determination utilizing multiple pressure measurements in reference pipe sections attached to the pump. The method of parameter extraction from redundant experimental data, as well as the modeling by an equivalent electrical network is shown. Results are presented for noncavitating and slightly cavitating flows. The quality of the results is an indication that the method utilized represents a successful way to determine the dynamic transfer matrix for a pump.
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Wu, Ke Liu, Xiang Fang Li, and Xiao Ting Gou. "Research on Variance Principle of Critical Producing Pressure Drop of Horizontal Well in Gas Reservoir with Bottom Water." Advanced Materials Research 616-618 (December 2012): 674–79. http://dx.doi.org/10.4028/www.scientific.net/amr.616-618.674.
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According to material balance principle, gas/water bearing height in gas reservoir with bottom water could be deduced. Additionally, sweep efficiency could be approximately determined, then based on the equivalent flowing resistance method and critical vertical velocity of bottom water drive, computational model of Critical Producing Pressure Drop during the development of gas reservoir with bottom water could be derived. Therefore, the variance principle of Critical Producing Pressure Drop of horizontal well can be expressed quantitatively, and this paper also analyzes that it is influenced by the ratio of vertical permeability to horizontal permeability, the difference between water and gas density, the ratio of water viscosity to gas viscosity and height for bottom water coning. The results could provide guidelines for the determination of reasonable producing pressure drop and producing rate of horizontal well in gas reservoir with bottom water.
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Williams, Joanne, C. W. Hughes, M. E. Tamisiea, and S. D. P. Williams. "Weighing the ocean with bottom-pressure sensors: robustness of the ocean mass annual cycle estimate." Ocean Science 10, no. 4 (2014): 701–18. http://dx.doi.org/10.5194/os-10-701-2014.
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Abstract. We use ocean bottom-pressure measurements from 17 tropical sites to determine the annual cycle of ocean mass. We show that such a calculation is robust, and use three methods to estimate errors in the mass determination. Our final best estimate, using data from the best sites and two ocean models, is that the annual cycle has an amplitude of 0.85 mbar (equivalent to 8.4 mm of sea level, or 3100 Gt of water), with a 95% chance of lying within the range 0.61–1.17 mbar. The time of the peak in ocean mass is 10 October, with 95% chance of occurring between 21 September and 25 October. The simultaneous fitting of annual ocean mass also improves the fitting of bottom-pressure instrument drift.
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Williams, Joanne, C. W. Hughes, M. E. Tamisiea, and S. D. P. Williams. "Weighing the ocean with bottom-pressure sensors: robustness of the ocean mass annual cycle estimate." Ocean Science Discussions 11, no. 1 (2014): 453–96. http://dx.doi.org/10.5194/osd-11-453-2014.
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Abstract. We use ocean bottom pressure measurements from 17 tropical sites to determine the annual cycle of ocean mass. We show that such a calculation is robust, and use three methods to estimate errors in the mass determination. Our final best estimate, using data from the best sites and two ocean models, is that the annual cycle has an amplitude of 0.85 mbar (equivalent to 8.4 mm of sea level, or 3100 Gt of water), with a 95% chance of lying within the range 0.61–1.17 mbar. The time of the peak in ocean mass is 10 October, with 95% chance of occuring between 21 September and 25 October. The simultaneous fitting of annual ocean mass also improves the fitting of bottom pressure instrument drift.
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Haider, Sara Thaier, Aqeel Al-Adili Al-Adili, and Rafid Kadhim Abbas. "Using a novel approach to determine the pore pressure of West Qurna 15 oil well in South of Iraq." Journal of Engineering 26, no. 10 (2020): 35–49. http://dx.doi.org/10.31026/j.eng.2020.10.03.
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Pore pressure means the pressure of the fluid filling the pore space of formations. When pore pressure is higher than hydrostatic pressure, it is named abnormal pore pressure or overpressure. When abnormal pressure occurred leads to many severe problems such as well kick, blowout during the drilling, then, prediction of this pressure is crucially essential to reduce cost and to avoid drilling problems that happened during drilling when this pressure occurred. The purpose of this paper is the determination of pore pressure in all layers, including the three formations (Yamama, Suliay, and Gotnia) in a deep exploration oil well in West Qurna field specifically well no. WQ-15 in the south of Iraq. In this study, a new approach of mechanical specific energy (MSE) was used to predict the pore pressure of the deep well WQ-15, and compare the results obtained with the previous techniques Magara, Eaton, Equivalent Depth and Sigma log along with the actual pore pressure using a statistical equation of Absolute Average Percentage Error (AAPE). The newly suggested approach obtained is good, and accepted results of pore pressure are encouraging to be applied in other oil wells rather than depending on previous traditional methods, especially when well logs are unavailable.
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Straumal, Boris B., Olga A. Kogtenkova, Ruslan Z. Valiev, Pawel Zięba, and Brigitte Baretzky. "Diffusion and Phase Transitions Accelerated by Severe Plastic Deformation." Diffusion Foundations 5 (July 2015): 95–108. http://dx.doi.org/10.4028/www.scientific.net/df.5.95.
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Severe plastic deformation (SPD) can lead to the phase transformations in the materials. Even the SPD-treatment at ambient temperatureTSPD= 300 K is frequently equivalent to the heat treatment at a certain elevated temperature (effective temperature)Teff> 300 K. However, if the real annealing at effective temperature leads to the grain growth, SPD leads to strong grain refinement. SPD also accelerates the mass transfer in the materials. In this review the methods of determination for effective temperature after high-pressure torsion of metallic alloys are discussed as well as SPD-driven acceleration of diffusion.
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Wang, Lei, Fen Shi, Zheng Wang, and Shuguo Liang. "Blockage Effects in Wind Tunnel Tests for Tall Buildings with Surrounding Buildings." Applied Sciences 12, no. 14 (2022): 7087. http://dx.doi.org/10.3390/app12147087.
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To study the blockage effects in wind tunnel tests for tall buildings with surrounding buildings and establish a reasonable calculation method for the blockage ratio, this paper carried out fifty-one test conditions of pressure model wind tunnel tests with three scale ratios. The tests considered the relative location, relative height, and model number of the surrounding buildings to those of the target building by the rigid pressure models. Based on the wind tunnel tests, the blockage effects on the pressure coefficients and drag coefficients were studied in detail. The results showed that the blockage effects were different when the relative positions of the surrounding models to the target model were different, even if the blockage ratio was the same. The blockage effects caused by the surrounding models with unit blockage ratio were usually more significant than those caused by the target pressure-measuring model itself. The existing correction methods for the blockage effects are mainly derived from the wind tunnel tests of an isolated building model. Using existing calculations to evaluate the blockage effect of wind tunnel tests for tall buildings with surrounding buildings may result in obvious deviations. Finally, the concept of the equivalent blockage ratio was proposed, which can be used to calculate the blockage ratio of wind tunnel tests of tall buildings with surrounding buildings. The proposed calculation method of this equivalent blockage ratio can provide a reference for the determination of scale ratios for wind tunnel test models of tall buildings.
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Kleppe, A. K., M. D. Welch, W. A. Crichton, and A. P. Jephcoat. "Phase transitions in hydroxide perovskites: a Raman spectroscopic study of stottite, FeGe(OH)6, to 21 GPa." Mineralogical Magazine 76, no. 4 (2012): 949–62. http://dx.doi.org/10.1180/minmag.2012.076.4.11.
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AbstractThe effect of pressure on the naturally occurring hydroxide-perovskite stottite, FeGe(OH)6, has been studied in situ by micro-Raman spectroscopy to 21 GPa at 300 K. The ambient spectrum contains six OH-stretching bands in the range 3064 3352 cm–1. The presence of six non-equivalent OH groups is inconsistent with space group P42/n. In view of this inconsistency a new ambient structure determination of stottite from Tsumeb was carried out, but this did not allow the clear rejection of P42/n symmetry. However, a successful refinement was also carried out in space group P2/n, a subgroup of P42/n, which allows for six non-equivalent O atoms. The two refinements are of comparable quality and do not allow a choice to be made based purely on the X-ray data. However, taken with the ambient and 150 K Raman spectra, a good case can be made for stottite having P2/n symmetry at ambient conditions. On this basis, the pressure induced spectroscopic changes are interpreted in terms of a reversible phase transition P2/n ↔ P42/n.
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Zou, Luyao, Xue Qu, Mengyao He, Qi Tang, Chenxuan Song, and Jianguo Wu. "Equivalent coefficient of plate stress of stiffened plates under moving slamming load." Journal of Physics: Conference Series 2964, no. 1 (2025): 012026. https://doi.org/10.1088/1742-6596/2964/1/012026.
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Abstract The slamming load acting on the bow of a large-bow flare ship is equivalent to a moving pulse time history with linear rise and exponential attenuation. The Abaqus finite element software is used to study the elastic dynamics of multiple stiffened plates under the action of the moving slamming load. Response calculations are conducted to analyze the influence of different load parameters on the dynamic response of the stiffened plate. The dynamic stress equivalent coefficient DLFps (Dynamic Load Factor of plate stress) of the plate is introduced, the change pattern and sensitivity between DLFps and the slamming load dimensionless parameters are analyzed, and the DLFps formula regression and verification are performed. A parameter determination method for the simplified slamming pressure model is proposed. Comparison with the results of the wedge-shaped body falling into the water test shows that the slamming stress equivalent formula DLFps of the plate proposed in this article has high accuracy and can be used to determine the slamming load of the ship structure.
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SANO, Masashi. "Pressure pulsations in turbo-pump piping systems (4th report, Effects of turbo-pump geometry on determination of the equivalent pipe length and pressure resonance)." Transactions of the Japan Society of Mechanical Engineers Series B 52, no. 474 (1986): 578–84. http://dx.doi.org/10.1299/kikaib.52.578.
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Li, Cui, Zhanbiao Li, Xingyu Wang, et al. "Using the Equivalent Static Pressure Method to Assess Free Fall Damage of the Korla Fragrant Pear." Horticulturae 9, no. 9 (2023): 993. http://dx.doi.org/10.3390/horticulturae9090993.
Full textAbstract:
In order to explore the equivalent static condition of the impact damage of the Korla fragrant pear under free fall, the Korla fragrant pear was chosen as the research object in this paper, and the height of free fall and rebound were recorded by a high-speed camera to obtain the impact damage energy of the fragrant pear. In addition, a mechanical compression test was conducted on the fragrant pear to obtain its static deformation energy, and the equivalent static condition of the impact damage was calculated based on the mechanical energy conservation formula using the damage volume of the fragrant pear as the evaluation standard. The test verification was carried out on the damaged fragrant pear using a scanning electron microscope test. This study showed that the falling and rebound height of the fragrant pear within the range of the test parameters and under the free fall test conditions conform to linear fitting. The coefficient of determination (R2) was 0.9951, and the impact damage occurred when the corresponding energy reached 205.89 × 10−3 J. When the damage energy was within 203.4 × 10−3 J and 498.23 × 10−3 J, the static damage volume of the fragrant pear was linearly correlated to the impact damage volume, R2 was 0.9944, and the maximum deviation between the predicted damage volume and the actual damage volume of the fragrant pear in the verification test was 4.4%. These data can provide a reference for research on the equivalent method of impact damage of the Korla fragrant pear, and provide theoretical guidance to the fruit industry to reduce damage and increase efficiency.
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Dresner, T. L., and K. W. Buffinton. "Definition of Pressure and Transmission Angles Applicable to Multi-Input Mechanisms." Journal of Mechanical Design 113, no. 4 (1991): 495–99. http://dx.doi.org/10.1115/1.2912810.
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Pressure angle is an important measure of the effectiveness with which a force is transmitted between a cam and follower. A pressure angle of zero degrees indicates that the force is transmitted with maximum effectiveness while a 90 deg pressure angle indicates that the force cannot make the desired contribution to the follower motion. There are a number of definitions available in the literature that can be used to determine pressure angle. These definitions are all consistent with the meaning of pressure angle described above when applied to followers driven by only a single cam. For followers driven by multiple inputs, however, we have found that none of these definitions provides a value of pressure angle that retains this same meaning. The purpose of this paper is to draw attention to this fact and to present a precise definition of pressure angle, as well as a discussion of its mathematical consequences, that property characterizes the performance of either single-input or multi-input cam-follower mechanisms. For single-input systems, this definition is shown to be equivalent to the definitions for pressure angle found in the literature. The applicability of this definition to the determination of transmission angle for linkages with multiple inputs is also discussed.
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Hu, Zhao Hui, Rong Guo Wang, Li Ma, and Shan Yi Du. "The Study of Thermal Boundary Condition for CFRP Pressure Vessel with Metallic Liner during Manufacture Process." Materials Science Forum 575-578 (April 2008): 1483–88. http://dx.doi.org/10.4028/www.scientific.net/msf.575-578.1483.
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The heat convection was considered the main heat exchange type in the autoclave where CFRP pressure vessel was cured in this analysis. To determine the heat convection coefficient, it needed the combination of theoretical calculation and temperature test. In the theoretical calculation, the determination of the heat convection coefficient was considered as an inversion problem of thermal conduction. By adjusting convection coefficient value in the finite element calculation, optimization method was employed to obtain a good agreement between calculated temperature and measured temperature. In the temperature test, the metallic liner of CFRP pressure vessel was used as test component to record temperature data which was compared with the calculated temperature. The calculated results reveal that the maximum value in convection coefficient sequence is 19.87 W/m2/K; the minimum value is 0.16 W/m2/K; the maximum temperature deviation between calculation and test is 1.67 °C. The results present the equivalent thermal boundary condition for the simulation of curing process of CFRP pressure vessel.
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Chung, Charles S., Audrey Strunc, Rachel Oliver, and Sándor J. Kovács. "Diastolic ventricular-vascular stiffness and relaxation relation: elucidation of coupling via pressure phase plane-derived indexes." American Journal of Physiology-Heart and Circulatory Physiology 291, no. 5 (2006): H2415—H2423. http://dx.doi.org/10.1152/ajpheart.00257.2006.
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Because systole and diastole are coupled and systolic ventricular-vascular coupling has been characterized, we hypothesize that diastolic ventricular-vascular coupling (DVVC) exists and can be characterized in terms of relaxation and stiffness. To characterize and elucidate DVVC mechanisms, we introduce time derivative of pressure (dP/d t) vs. time-varying pressure [P( t)] (pressure phase plane, PPP)-derived analogs of ventricular and vascular “stiffness” and relaxation parameters. Although volume change (dV) = 0 during isovolumic periods, and time-varying left ventricular (LV) stiffness, typically expressed as change in pressure per unit change in volume (dP/dV), is undefined, our formulation allows determination of a PPP-derived stiffness analog during isovolumic contraction and relaxation. Similarly, an aortic stiffness analog is also derivable from the PPP. LV relaxation was characterized via τ, the time constant of isovolumic relaxation, and vascular (aortic pressure decay) relaxation was characterized in terms of its equivalent (windkessel) exponential decay time constant κ. The results show that PPP-derived systolic and diastolic ventricular and vascular stiffness are strongly coupled [Formula: see text]. In support of the DVVC hypothesis, a strong linear correlation between relaxation (rate of pressure decay) indexes κ and τ (κ = 9.89τ − 90.3, r = 0.81) was also observed. The correlations observed underscore the role of long-term, steady-state DVVC as a diastolic function determinant. Awareness of the PPP-derived DVVC parameters provides insight into mechanisms and facilitates quantification of arterial stiffening and associated increase in diastolic chamber stiffness. The PPP method provides a tool for quantitative assessment and determination of the functional coupling of the vasculature to diastolic function.
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Romanowicz, Paweł J., and Bogdan Szybiński. "Determination of Optimal Flat-End Head Geometries for Pressure Vessels Based on Numerical and Experimental Approaches." Materials 14, no. 10 (2021): 2520. http://dx.doi.org/10.3390/ma14102520.
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The experimental and numerical analyses of the pressure vessels with different flat ends are presented and discussed in the paper. The main aim of the study is to propose the optimal flat head end geometry. The analyses are focused on the comparison of standardized geometries and with the proposed elliptical cut-out. The experimental tests with the application of strain-gauge measurements and numerical modeling of the pressure vessel are conducted. The behavior under low and high pressures and the influence of the residual welding stresses, material properties, and geometrical tolerances on the level of the plastic deformation in the flat end is discussed. It is presented that the rules given in the recent standard are not sufficient for optimal selection of the optimal geometry. It is observed that in certain geometries the deviations of the pipe thickness may lead to a significant increase of the equivalent stresses. The residual welding stresses have a significant influence on the stress and strain level—particularly in the stress relief groove (SRG). The performed study and comparison of the different geometries allow for the proposal of the optimal shape of the flat end. It appeared that the pressure vessels with SRG are the most optimal choice, particularly when elliptic shapes are in use. In some cases (i.e., pipe with wall-thickness equal to 40 mm and the flat end with circular SRG), the optimal configuration is reached for dimensions beyond the admissible by code range.
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Jiang, Nan, Yuqi Zhang, Tingyao Wu, Yingkang Yao, and Xuedong Luo. "Determination of Blasting Vibration Safety Criterion for HDPE Pipeline Using Vibration and Strain Data in a Coastal Metro Line." Sensors 21, no. 21 (2021): 7252. http://dx.doi.org/10.3390/s21217252.
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A key aspect of urban blasting engineering is evaluating the safety of the blasting dynamic load on the adjacent high-density polyethylene water supply pipeline and controlling the negative impact of the blasting vibration load on the pipeline. According to the special characteristics of the soil layer in Shenzhen coastal city, a field blasting test of a full-scale pre-buried HDPE pipeline was carried out, and the distribution characteristics of the blasting vibration velocity and dynamic strain were analyzed. The finite element model was established by LSDYNA, and the reliability of the calculation model and parameters was verified by comparing with the field test data. At the same time, the dynamic response characteristics of pipelines with different buried depths, operating water conveyance pressures, and diameters under blasting vibration loads were studied. Combined with the circumferential allowable stress control criterion of the pipeline, the safety control standard of the blasting vibration velocity of the HDPE water supply pipeline under different working conditions was proposed. The results show that the circumferential compressive strain of the HDPE pipe is the most affected by blasting vibration, and the pipe with the shortest blasting center distance has the largest response. The vibration velocity and equivalent stress of the pipeline increase with the increase of buried depth, internal pressure, and diameter. The vibration velocity and equivalent stress of the explosion side at the same section of the pipeline are greater than those of the back explosion side. Based on the dimensionless analysis, the vibration velocity prediction model of the buried depth, operating pressure, and diameter of the pipeline is proposed. The safety control velocity of the pipeline is 25 cm/s, and the vibration velocity of the upper surface is 22.5 cm/s according to the Mises yield strength criterion.
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Rusin, Dawid, Janusz Juraszek, and Piotr Woźniczka. "Experimental Determination of the Equivalent Moment of Inertia and Stresses of Aluminium Profiles with Thermal Breaks." Materials 18, no. 1 (2024): 23. https://doi.org/10.3390/ma18010023.
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This paper presents the results of experimental tests and computer simulations on the stiffness of composite aluminium mullions used in unitised façades. The elements analysed were subjected to bending in order to simulate the actual operating conditions of aluminium façades subjected to significant wind pressure or suction loads. The basic mechanical and physical properties of the materials from which the analysed type of aluminium façade is made (Aluminium EN AW-6060 in the T66 temper and polyamide PA66 25GF), the test method, and the results obtained are described. As a result of the tests, equivalent moments of inertia of the composite profile (aluminium profile with the thermal break) were determined, which are strongly dependent on the strength of the connection between the individual elements, the asymmetry of the cross-section, and the properties of the thermal break. Strain measurements carried out using FBG (Fiber Bragg Grating) strain sensors installed in the profiles under tests allowed for determining the actual stress values of the aluminium profiles under consideration. The results obtained were compared to theoretical (numerical) values, indicating discrepancies at higher load values. The methodology presented in this article is to be used to monitor the deformation of the aluminium façade mullions of HRB (High-Rise Buildings).
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Escobar, Freddy Humberto, Aura María López, and José Humberto Cantillo. "EFFECT OF THE PSEUDOTIME FUNCTION ON GAS RESERVOIR DRAINAGE AREA DETERMINATION." CT&F - Ciencia, Tecnología y Futuro 3, no. 3 (2007): 113–24. http://dx.doi.org/10.29047/01225383.480.
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The gas flow equation is normally linearized to allow the liquid solution of the diffusivity equation to satisfy gas behavior when analyzing transient test data of gas reservoirs. When wellbore storage conditions are insignificant, drawdown tests are best analyzed using the pseudopressure function. On the other hand, buildup pressure tests require linearization of both pseudotime and pseudopressure. It is not the case for the TDS technique which is indifferently applied to either drawdown or buildup tests. However, whichever the case, pseudotime has certain effect at very long testing times in formations of moderate to high permeability. In this paper, we implemented the Tiab’s Direct Synthesis (TDS) technique, to include pseudotime effects, and observe its influence on the interpretation results of gas well test data at early and late time periods. New analytical equations to estimate reservoir permeability, wellbore storage coefficient, pseudoskin factor and reservoir drainage area are presented. Then, a comparison of results against rigorous time was carried out for simulated and field cases. We found acceptable results for permeability, pseudoskin factor and wellbore storage coefficient. However, for the case of reservoir drainage area, the deviation error was of 4,1% for a simulated case and 17,9% for a field case. However, the smaller of these deviations may be small if related to pressure transient analysis results. However, this deviation in a gas reservoir with reserves of one tera standard cubic feet is equivalent to a huge difference of 38 gigas of standard cubic feet of gas which may have an economic impact to any oil company.
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Yu, Xiaozhe, Xingqing Yan, Yue Li, Fangchi Zeng, Shouli Kang, and Jianliang Yu. "Determination of the Plastic Stress–Strain Relationship of a Rupture Disc Material with Quasi-Static and Dynamic Pneumatic Bulge Processes." Processes 10, no. 8 (2022): 1463. http://dx.doi.org/10.3390/pr10081463.
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Rupture discs, manufactured using a hydraulic or pneumatic bulge process, are widely used to protect vessels from over-pressuring. The stress–strain relationship of the material in the bulge process plays a major role in understanding the performance of rupture discs. Moreover, both the theoretical analyses and numerical simulations of rupture discs demand a reliable stress–strain relationship of the material in a real bulge process. In this paper, an approach for determining the plastic stress–strain relationship of a rupture disc material in the bulge process is proposed based on plastic membrane theory and force equilibrium equations. Pressures of compressed air and methane/air mixture explosions were used for the bulge pressure to accomplish the quasi-static and dynamic bulge processes of tested discs. Experimental apparatus for the quasi-static bulge test and the dynamic bulge test were built. The stress–strain relations of 316L material during bulge tests were obtained, compared, and discussed. The results indicated that the bulge height at the top of the domed disc increased linearly with an increase in bulge pressure in the quasi-static and dynamic bulge processes, and the effective strain increased exponentially. The rate of pressure rise during the bulge process has a significant effect on the deformation behavior of disc material and hence the stress–strain relationship. At the same bulge pressure, a disc tested with a larger pressure rise rate had smaller bulge height and effective strain. At the same effective stress at the top of the domed disc, discs subjected to a higher pressure rise rate had smaller effective strain, and hence they are more difficult to rupture. Hollomon’s equation is used to represent the relationship between the effective stress and strain during bulge process. For pressure rise rates in the following range of 0 (equivalent to quasi-static condition), 2–10 MPa/s, 10–50 MPa/s, and 50–100 MPa/s, the relation of stress and strain is σe = 1259.4·εe0.4487, σe = 1192.4·εe0.3261, σe = 1381.2·εe0.2910, and σe = 1368.4·εe0.1701, respectively.
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Posmituha, Olexander, Svyatoslav Kravets, Volodymyr Suponyev, and Kazimir Glavatsky. "Determination of equivalent and optimal sizes of wedge tip from flange for the static perforation of soil." MATEC Web of Conferences 230 (2018): 01011. http://dx.doi.org/10.1051/matecconf/201823001011.
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The purpose of the study is to create a new design of the working tip for the perforation of the soil when laying two or more buildings trenchless way and determine its rational parameters. Method. It is known that for static perforation in the formation of cavities in the soil for communication is traditionally used cone-shaped working elements, which is the most common, cheap and reliable. However, the study revealed inefficiency. The design of the working elements of the soil perforation for trenchless laying of two or more buildings simultaneously in the form of a tip, which consists of a wedge-shaped part and a control part in the form of a rectangle with half-cylinders. The basic principles and mathematical dependences of determining the size of the working body are described. Scientific novelty. Regularities of changes in soil pressure on the lateral, conical and wedge surface, flat and cylindrical part of the tip, allowed to obtain an analytical dependence for the calculation of the resistance force depending on the physical and mechanical properties of the soil, the diameter and the number of cases established simultaneously. Also, when comparing the cone-cylindrical and flat tips, it can be argued that the breakdown force of the flat tip decreases from 1.2 to 1.7 times.
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Beyaz, Turgay, and Şeyda Özçelik. "Is There any Effect of Sample Sizes on Laboratory Liquefaction Tests?" Academic Perspective Procedia 2, no. 3 (2019): 750–57. http://dx.doi.org/10.33793/acperpro.02.03.82.
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Determination of liquefaction potential of sands in laboratory; dynamic three axial, hollow cylindrical torsional shear, resonance column, bender elements and cyclic simple shear tests are used. In this study, the effect of sample size on the determination of liquefaction energy of sandy soils in cyclic simple shear test apparatus was investigated. Uniform clean sea sand was used in the study. The cell inner diameter in which the samples to be tested is placed is 50 mm. Samples were prepared three different sizes with a length/diameter (H/D) ratio of 1, 0.5 and 0.25 and four varied relative densities (Dr: 40%, 50%, 60% and 70%). The samples were subjected to 1D cyclic loading at a frequency of 0.1 Hz under 100 kPa vertical stress and 50 kPa pore pressure. Each experiment was repeated 3 times, with equivalent or closer results considered significant. According to the test results, the liquefaction energy values per volume (J/m3) of the samples of different sizes are different from each other.
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Ciulli, E. "A Review of Internal Combustion Engine Losses Part 2: Studies for Global Evaluations." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 207, no. 3 (1993): 229–40. http://dx.doi.org/10.1243/pime_proc_1993_207_184_02.
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The global evaluation of losses is important in providing information about the behaviour of an engine. This may be used, for instance, in design and development of new models, where one with inherently the lowest friction may be chosen with a consequent potential gain in fuel economy. This paper reviews studies on the determination of total engine losses. Experimental works are reported from which, sometimes with theoretical support, empirical formulae are obtained that allow an extension of the results to engines similar to those investigated. Besides formulae in which losses are expressed as an equivalent pressure averaged in the complete cycle, more detailed formulae for the determination of instantaneous loss torques are reported, which are also useful in obtaining a better evaluation of the engine speed trend in fault diagnosis. All formulae can be used in computer programs for the numerical simulation of engine performance, a use that can reduce the time needed for experimental work.
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Saber, Karim, Alyen Abahazem, Nofel Merbahi, and Mohamed Yousfi. "Electrical Equivalent Circuit of Multi-Tips Pulsed Corona Discharge Reactor." MATEC Web of Conferences 348 (2021): 01014. http://dx.doi.org/10.1051/matecconf/202134801014.
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In this work, an electrical model equivalent to the corona discharge reactor has been proposed in a multitips plan configuration, in dry air at atmospheric pressure. The electrical parameters evolution of the circuit are obtained by using the identification method which is based on the least squares recursive (RLS) algorithm, the estimated parameters allow us to describe the corona discharge behavior inside the reactor. The RLS method used during the determination of capacitance and resistance is validated by the comparison between the measured and the calculated currents, the significant forms of capacitance and resistance confirm the validity of the proposed electrical model. The estimated parameters of the electrical circuit allowed us to determine the discharge power, the power delivered to the reactor and thus the energy efficiency during the discharge, this efficiency increases during the propagation of streamers towards the plane, it reaches a maximum value which is equal to 50% in the case of the fourtips- plane configuration. The energy stored in the reactor is also calculated using the electrical circuit, it increases to a maximum value of 2.6 pJ, which is a very low value compared to the energy delivered to the reactor. This work allows us to control the discharge and lost energy during the corona discharge in the case of multi-tips-plane configuration.
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Eminov, Ramiz A., Elmir I. Huseynli, and Saida I. Kerimova. "A method for identifying leaks in water pipes by controlling the pressure gradient." Journal «Izvestiya vuzov. Investitsiyi. Stroyitelstvo. Nedvizhimost» 10, no. 4 (2020): 628–33. http://dx.doi.org/10.21285/2227-2917-2020-4-628-633.
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The objective was to develop a method for determining leaks in a branchless water pipeline section, when a pressure drop in the pipe under the action of friction forces is observed. The problem of detecting leaks can be solved by developing new methods for monitoring the operation of water supply and distribution systems. A well-known method for detecting leaks in branchless pipelines consists in determination of the coordinates of the intersection point of lines that characterize the pressure change in the pipe before and after the leak incident. On this basis, a method is proposed for determining several leak locations in the water supply system with fewer necessary measurements. A well-known method for determining leaking sites in a horizontal water supply section with a constant pipe diameter was analysed. One disadvantage of this method is that determination of a leaking site may require numerous measurements to establish the ratio of the pipeline length to the most likely minimum length of the interval between nearby leak points. The developed method for detecting water leaks by monitoring the pressure gradient eliminates this drawback. A method of equivalent points was proposed, which allows the number of necessary measurements to be significantly reduced. Formulas were obtained for estimating the multiplicity of reducing the number of necessary measurements in the proposed method. It was determined that, upon an excessive increase in the number of leak points, the specified multiplicity decreases to zero. However, this indicates a completely obsolete water supply system, which requires replacement
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Perl, M. "The Change in Overstrain Level Resulting From Machining of an Autofrettaged Thick-Walled Cylinder." Journal of Pressure Vessel Technology 122, no. 1 (1999): 9–14. http://dx.doi.org/10.1115/1.556145.
Full textAbstract:
An analytical model for predicting the level of autofrettage following either inner, outer, or combined machining of a gun barrel is developed based on Hill’s (Hill, R., 1950, The Mathematical Theory of Plasticity, Clarendon Press, Oxford, U.K.) solution for the autofrettage residual stress field. The analysis results in very simple algebraic expressions for the post-machining level of autofrettage in terms of the original level induced in the blank tube. In parallel, a finite element analysis of the machining process is performed in which the residual stress field is simulated by an equivalent thermal load. The numerical results are found to be in excellent agreement with the analytical ones. Thus, as an equivalent thermal load can always be determined, either analytically or numerically, for any other approximations to the residual stress field due to autofrettage (Perl, M., 1988, ASME J. Pressure Vessel Technol., 110, pp. 100–102), the foregoing methodology can be readily applied, enabling the determination of post-machining autofrettage level in these cases. [S0094-9930(00)00501-1]
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Pastor Monteza, Luis, Marco Castro Rivera, Lenin Quiñones Huatangari, and Eli Morales Rojas. "Sound Pressure Level at Terminals through Data Mining." Scientific Programming 2023 (January 13, 2023): 1–8. http://dx.doi.org/10.1155/2023/8776630.
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The land transportation is a cause of noise in cities, thus breaking the natural balance and bringing with it physiological and mental illnesses, as well as occupational accidents. In this sense, the objective of the research was to estimate the sound pressure in land terminals in the city of Jaen, Peru, using data mining algorithms. The methodology consisted in environmentally monitoring six terminals in the city of Jaen, during 2019, using a class 1 sound level meter; the exploratory analysis of the collected variables that influence the noise of the terminals (minimum and maximum sound pressure level, number of light and heavy vehicles, and equivalent sound pressure level) was performed, which were grouped into three groups of variables for the purpose of using data mining algorithms. Three algorithms were used, namely, artificial neural network, linear regression, and M5Rules, using the free software Weka. Considering all variables, the M5Rules method performed the best, because the value of the mean absolute error (0.7462), the root mean square error (1.0575), and uncertainty analysis (0.09) was the smallest compared to the other two methods. However, for the two remaining groups of variables, the linear regression model showed the lowest mean absolute error and mean square root of the error; in addition to presenting coefficients of determination close to one. The algorithms show good behavior when estimating the sound pressure of the terminals in the city of Jaen.
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Rutkowski, M. A., A. S. Shybeka, and K. I. Halynia. "Hydraulic Calculation of Copper Pipelines for Heating and Internal Gas Supply Systems." Science & Technique 17, no. 6 (2018): 508–14. http://dx.doi.org/10.21122/2227-1031-2018-17-6-508-514.
Full textAbstract:
Copper pipelines are widely used while designing modern heating systems, water and gas supply of residential buildings and these pipelines have a number of advantages in comparison with steel and plastic pipelines. The main reason for limited use of copper pipes is their cost which is practically twice as much as cost of steel pipes, and four times higher than the coat of polypropylene pipes. Modern design standards in Belarus do not contain specific requirements for calculation of copper pipelines. Therefore hydraulic calculation of heating systems has been considered and analyzed on the basis of norms of Russian Federation. The drawback of all theoretical calculations presented in Russian standards is their abstraction from general laws of fluid and gas mechanics. For this reason theoretical foundations of hydraulic calculations for all pipelines have been considered and expressions have been given for determination of pressure loss due to friction and in local loss. Main flow regimes have been considered on the basis of I. Nikuradze’s experiments in order to determine linear losses and dependences for determination of friction coefficient in laminar, transient and turbulent modes have been presented in the paper. Values of local loss coefficient for main pipeline elements are given for calculation of pressure loss and the paper also shows determination of value z with due account of equipment capacity. An analysis of nomograms presented in Russian norms and researches has been carried out; shortcomings have been revealed and the ways directed on their perfection have been found. Nomograms for calculation of specific pressure losses in heating systems and internal gas supply have been constructed on the basis of natural gas and propane with due account of dependences presented in the paper. Nomograms for finding equivalent length of a single local loss have been constructed for calculation of internal gas supply systems.
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A. C., Tomiwa,, and Oladele, O. O. "Determination of Noise Pollution Base from Welding and Fabrication Workshop in Akungba-Akoko, South West Nigeria." Advanced Journal of Science, Technology and Engineering 4, no. 4 (2024): 155–69. https://doi.org/10.52589/ajste-jkhuus7d.
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Determination of noise pollution base line of welding and fabrication workshop was carried out at some designated welding and fabrication workshops. These measurements was carried out in 10 different locations using the digital sound level meter of model 40773L. The sound pressure Level (SPL) was measured for every 2 minutes for 2hrs (120mins) and the equivalent noise level (Leq), Percentile (L10, L90) and the Noise Pollution Level (LNP) was also calculated. Fast Fourier Transformation was used to interpolate between minutes to give value in seconds and transformed measured values of time to frequency domain. Graphs were also plotted for noise against time and for power against the transformed measured values which are in frequency domain. The result of the research show that the equivalent continuous noise level in the selected site are SITE A: 94.74Db, SITE B: 89.82dB, SITE C: 92.90dB, SITE D: 90.03dB, SITE E: 87.10dB, SITE F: 87.86dB, SITE G: 91.33dB, SITE H: 92.86dB, SITE I: 89.24dB, and SITE J: 89.02dB, showing that some sites are noisier than others and the sum of the average values of noise data in welding and fabrication workshop in Ondo State metropolis is 90.50dB Results obtained are above the FEPA recommended values 90 dB for 8hrs exposure time, which put limitations to effectiveness of signal transmissions that may lead to the possible health hazard. The noise level highlighted which include Annoyance, Cardiovascular disturbance, and impalement of task performance and induced hearing loss. Appropriate suggestions which include the use of ear muffs have been made in order to prevent these hazards.
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V. I. PETRENKO, V. D. PETRENKO, and O. L. TIUTKIN. "GROUND AND GENERAL METHODOLOGICAL DEVELOPMENTS OF SAFETY PROBLEM BY EXPLOSION OF THE METRO OBJECTS." Bridges and tunnels: Theory, Research, Practice, no. 8 (December 21, 2015): 65–73. http://dx.doi.org/10.15802/bttrp2015/90850.
Full textAbstract:
Purpose. The metro is the transporting system, which is most subject to internal influences negatively influencing on its work. The blast impact is one of such influences, thus the analysed history of explosions in metro testifies to the serious problem of safety. The decision of this problem consists in minimization of reason causing emergency and catastrophic situations. Methodology. For the decision of safety problem by explosion and blast protection of objects of metro bases and methodological developments of dynamic calculation of construction on the first stage are offered. Findings. The basic parameters of impact and blast waves at the explosions which affect internal and bearing constructions of metro are certain. It is found out that in the case of falling pressures and weakening of impulse value it is necessary to conduct a dynamic calculation only on complete pressure in the compression phase. In the case when action of complete pressure and impulse is equivalent, determination of loading is complicated. The however got graph of dependence of pressure impulse of air-blast wave in the phase of compression from the distance and mass of charge allows to get the values of loading for different cases. Using position of dynamic tasks about the analysis of the deformed state (calculation on the second maximum state) on the base of finite elements method it is possible to take power approach for determination of the state of construction at explosive influence. Formulas in a tensor form for practical determination of energy of deformation or destruction in a point, and also formulas of energy for shock and shock and air waves are offered. Originality. The joint decision of the offered equalizations of power approach enables to estimate the degree of deformation or destruction of underground building construction. Practical value. Application of power approach to the decision of dynamic task of explosion and determination of his action on construction of underground building allows the calculations to energy of constructions deformation at dynamic influences.