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1
Ekström, Magnus. "On the consistency of the maximum spacing method." Journal of Statistical Planning and Inference 70, no. 2 (July 1998): 209–24. http://dx.doi.org/10.1016/s0378-3758(97)00185-7.
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Weissman-Miller, Deborah. "On Predicting Survival in Prostate Cancer: Using an Extended Maximum Spacing Method at the Change Point of the Semiparametric Ratio Estimator (SPRE)." International Journal of Statistics and Probability 5, no. 2 (February 10, 2016): 19. http://dx.doi.org/10.5539/ijsp.v5n2p19.
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<p>Prostate cancer is a condition of public health significance in the United States. A new method for predicting survival is derived for the domain around the change point from a semiparametric ratio estimator (SPRE) to predict survival in response to treatment for prostate cancer. Using an extended maximum spacing estimator, the geometric mean of sample spacings from a uniform distribution <span style="font-family: Times New Roman; font-size: medium;"> is derived </span>with known endpoints given at 0 and at the value of the change point from an ordinary least squares (OLS) regression for SPRE. To determine the maximum interval on the ‘x’ axis between point estimates, the maximum spacing estimation method is derived from a continuous univariate distribution where spacing will be defined as gaps between ordered values of the distribution function. The maximum is defined as a single value in the neighborhood of the change point and spacing defined as a function of time. This maximum spacing defines the gaps between point estimates at each time-dependent predicted outcome from the change point and results in a semiparametric ratio estimator that is reliable and repeatable. Performance is discussed through a simulation of change point values for a real application in clinical medicine and, using SPRE, in personalized medicine for a single prostate cancer patient.</p>
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Wong, Tommy S. W., and Wung-Hee Moh. "Effect of maximum flood width on road drainage inlet spacing." Water Science and Technology 36, no. 8-9 (October 1, 1997): 241–46. http://dx.doi.org/10.2166/wst.1997.0673.
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Based on the kinematic wave theory, a method has been developed for the determination of road drainage inlet spacing under the continuous grade condition. The input data required are the allowable maximum flood with, the physical characteristics of the roadway, the empirical relationship between the maximum discharge and the intercepted flow, and the rainfall intensity-duration curve. By applying the method to a roadway with the standard drainage inlet used in Singapore, the effect of maximum flood width on the inlet spacing has been assessed. The assessment shows that for a given maximum flood width, the inlet spacing is wider for roads with steeper cross and longitudinal slopes. An increase in maximum flood width gives an exponential increase in inlet spacing.
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Almongy, Hisham M., Fatma Y. Alshenawy, Ehab M. Almetwally, and Doaa A. Abdo. "Applying Transformer Insulation Using Weibull Extended Distribution Based on Progressive Censoring Scheme." Axioms 10, no. 2 (May 21, 2021): 100. http://dx.doi.org/10.3390/axioms10020100.
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In this paper, the Weibull extension distribution parameters are estimated under a progressive type-II censoring scheme with random removal. The parameters of the model are estimated using the maximum likelihood method, maximum product spacing, and Bayesian estimation methods. In classical estimation (maximum likelihood method and maximum product spacing), we did use the Newton–Raphson algorithm. The Bayesian estimation is done using the Metropolis–Hastings algorithm based on the square error loss function. The proposed estimation methods are compared using Monte Carlo simulations under a progressive type-II censoring scheme. An empirical study using a real data set of transformer insulation and a simulation study is performed to validate the introduced methods of inference. Based on the result of our study, it can be concluded that the Bayesian method outperforms the maximum likelihood and maximum product-spacing methods for estimating the Weibull extension parameters under a progressive type-II censoring scheme in both simulation and empirical studies.
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Sumner, David. "A Comparison of Data-Reduction Methods for a Seven-Hole Probe." Journal of Fluids Engineering 124, no. 2 (May 28, 2002): 523–27. http://dx.doi.org/10.1115/1.1455033.
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Two data-reduction methods were compared for the calibration of a seven-hole conical pressure probe in incompressible flow. The polynomial curve-fit method of Gallington and the direct-interpolation method of Zilliac were applied to the same set of calibration data, for a range of calibration grid spacings. The results showed that the choice of data-reduction method and the choice of calibration grid spacing each have an influence on the measurement uncertainty. At high flow angles, greater than 30 deg, where flow may separate from the leeward side of the probe, the direct-interpolation method was preferable. At low flow angles, less than 30 deg, where flow remains attached about the probe, neither data-reduction method had any advantage. For both methods, a calibration grid with a maximum interval of 10 deg was recommended. The Reynolds-number sensitivity of the probe began at Re=5000, based on probe diameter, and was independent of the data-reduction method or calibration grid spacing.
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Liu, Yang, Changfu Zong, Xiaojian Han, Dong Zhang, Hongyu Zheng, and Chunmei Shi. "Spacing Allocation Method for Vehicular Platoon: A Cooperative Game Theory Approach." Applied Sciences 10, no. 16 (August 12, 2020): 5589. http://dx.doi.org/10.3390/app10165589.
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Recently, spacing policies of the vehicular platoon have been widely developed to enhance safety, traffic efficiency, and fuel consumption. However, the integrated spacing policies aim to maximum overall benefit, and the distributed spacing policies intense to get optimal monomer benefit. Ignoring the fairness of the benefit allocation of each vehicle will reduce the motivation to constitute the platoon. To fill this critical gap, this study proposes a spacing allocation method by treating spacing decisions as cooperative games. A flock’s model which is used to be the payoff function is introduced based on bionic motion principles. We present a characteristic function of the platoon for the cooperative game model considering the specific structure of the platoon. The τ value, Shapley value, and average lexicographic value are introduced and applied to allocate the spacing fairly. Proposed methods are compared with constant distance policy in some typical situations. The simulation results demonstrate that the spacing policy based on cooperative game theory improved the stable time for consistency control and the convergence of longitudinal following error.
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Alshenawy, R., Ali Al-Alwan, Ehab M. Almetwally, Ahmed Z. Afify, and Hisham M. Almongy. "Progressive Type-II Censoring Schemes of Extended Odd Weibull Exponential Distribution with Applications in Medicine and Engineering." Mathematics 8, no. 10 (October 1, 2020): 1679. http://dx.doi.org/10.3390/math8101679.
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In this paper, the parameters of the extended odd Weibull exponential distribution are estimated under progressive type-II censoring scheme with random removal. The model parameters are estimated using the maximum product spacing and maximum likelihood estimation methods. Further, we explore the asymptotic confidence intervals and bootstrap confidence intervals for the model parameters. Monte Carlo simulations are performed to compare between the proposed estimation methods under progressive type-II censoring scheme. An empirical study using two real datasets form engineering and medicine fields to validate the introduced methods of inference. Based on our study, we can conclude that the maximum product of spacing method outperforms the maximum likelihood method for estimating the extended odd Weibull exponential (EOWE) parameters under a progressive type-II censoring scheme in both numerical and empirical cases.
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Abu El Azm, Wael S., Ehab M. Almetwally, Abdulaziz S. Alghamdi, Hassan M. Aljohani, Abdisalam Hassan Muse, and O. E. Abo-Kasem. "Stress-Strength Reliability for Exponentiated Inverted Weibull Distribution with Application on Breaking of Jute Fiber and Carbon Fibers." Computational Intelligence and Neuroscience 2021 (September 21, 2021): 1–21. http://dx.doi.org/10.1155/2021/4227346.
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For the first time and by using an entire sample, we discussed the estimation of the unknown parameters θ 1 , θ 2 , and β and the system of stress-strength reliability R = P Y < X for exponentiated inverted Weibull (EIW) distributions with an equivalent scale parameter supported eight methods. We will use maximum likelihood method, maximum product of spacing estimation (MPSE), minimum spacing absolute-log distance estimation (MSALDE), least square estimation (LSE), weighted least square estimation (WLSE), method of Cramér-von Mises estimation (CME), and Anderson-Darling estimation (ADE) when X and Y are two independent a scaled exponentiated inverted Weibull (EIW) distribution. Percentile bootstrap and bias-corrected percentile bootstrap confidence intervals are introduced. To pick the better method of estimation, we used the Monte Carlo simulation study for comparing the efficiency of the various estimators suggested using mean square error and interval length criterion. From cases of samples, we discovered that the results of the maximum product of spacing method are more competitive than those of the other methods. A two real‐life data sets are represented demonstrating how the applicability of the methodologies proposed in real phenomena.
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Sheng, Xiaofei, Jianguo Shen, Yongjin Shen, Liufang Zhu, and Defu Zang. "Measurement of formation conductivity through-casing using a TEM method." Journal of Geophysics and Engineering 16, no. 2 (April 1, 2019): 439–50. http://dx.doi.org/10.1093/jge/gxz022.
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Abstract Due to the existence of the metal casing in production wells, it is difficult for a conventional well-logging method to achieve satisfactory results. To study the possibility of measuring the formation conductivity through casing by using a transient electromagnetic (TEM) method, characteristics of the response signals received at different source-receiver spacing are investigated. Based on the advantages of the response signals at long spacing in the separation of the direct and indirect coupled signals, the corresponding differential response signals calculated with different formation conductivities are studied further. Results show that: (1) the differential signals are three orders of magnitude smaller than that of the original response signals; (2) there is a maximum and a minimum in the differential signal; (3) with the increase of the spacing, the profile of differential signal hardly changes, but moves backward on the timeline and the amplitude decreases slowly, which is in sharp contrast to the original response signals and (4) the differential signal is proportional to the difference of corresponding formation conductivities and the maximum and minimum values in the response difference are the most sensitive. The research reveals the characteristics of TEM responses in cased-hole and the distribution of formation conductivity information, which is predicted to provide a new perspective for the design of long-spacing through-casing in the TEM conductivity logging tool and the signal processing method.
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Al Shalaby, N., and S. G. El-Sherbiny. "Mutual Coupling Reduction of DRA for MIMO Applications." Advanced Electromagnetics 8, no. 1 (May 18, 2019): 75–81. http://dx.doi.org/10.7716/aem.v8i1.730.
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In this paper, A multiple input Multiple Output (MIMO) antenna using two Square Dielectric Resonators (SDRs) is introduced. The mutual coupling between the two SDRAs is reduced using two different methods; the first method is based on splitting a spiral slot in the ground plane, then filling the slot with dielectric material, "E.=2.2". The second method is based on inserting a copper parasitic element, having the same shape of the splitted Spiral, between the two SDRAs. The effect of replacing the copper parasitic element with Carbon nanotubes (CNTs) parasitic element "SOC12 doped long-MWCNT BP" is also studied. The antenna system is designed to operate at 6 GHz. The analysis and simulations are carried out using finite element method (FEM). The defected ground plane method gives a maximum isolation of l8dB at element spacing of 30mm (0.6λo), whereas the parasitic element method gives a maximum isolation of 42.5dB at the same element spacing.
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Lian, Y., Z. Xu, H. Pei, C. Liang, Y. Zhang, Z. Wen, and Z. Yue. "Influence of Film-Cooling Hole Arrangement on Mechanical Properties of Cooled Turbine Blade Based on the Crystal Plastic Theory." Journal of Mechanics 35, no. 6 (August 8, 2019): 809–28. http://dx.doi.org/10.1017/jmech.2019.4.
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ABSTRACTThe crystal plastic theory was used to examine the effect of film-cooling hole arrangements on mechanical properties of cooled turbine blade. The finite element method was used to analyze the maximum von Mises stress and resolved shear stress of an octahedral slip system considering the number of rows, diameter, spacing, and tangential-to-longitudinal hole spacing (h/l) ratio. The different arrangements were found to have a significant influence on the maximum von Mises stress and resolved shear stress. For the triangular arrangement, the von Mises stress and resolved shear stress were highest with double rows, followed by a single row and then triple rows. For the quadrilateral arrangement, the stresses were highest with double rows, followed by triple rows and then a single row. Increasing the spacing or decreasing the diameter reduced the maximum von Mises stress and weakened the multi-hole interference effect. Both the maximum von Mises stress and resolved shear stress decreased with the h/l ratio.
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Hamid, Marawan, Ali Joudah, and Alyaa Mohammed. "Reinforcement bars tying types in reinforced concrete." MATEC Web of Conferences 162 (2018): 04023. http://dx.doi.org/10.1051/matecconf/201816204023.
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In huge reinforced concrete structures, it is often difficult to distribute the reinforcing bars, especially at the connection regions, to keep the spacing between bars within the minimum acceptable limits as recommended in the global specifications standard, by using the common methods such as, overlapping or welding, therefore, a new method for bonding was introduced, using mechanical joints and electro fusion bonding method, and comparing these methods with the maximum strength of reinforcing bars without joints and the failure location within maximum strength limits outside the joints.
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Parveen, Sultan, Sanjay Kumar Singh, Umesh Singh, and Dinesh Kumar. "A Comparative Study of Traditional and Kullback-Leibler Divergence of Survival Functions Estimators for the Parameter of Lindley Distribution." Austrian Journal of Statistics 48, no. 5 (July 30, 2019): 45–53. http://dx.doi.org/10.17713/ajs.v48i5.772.
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A new point estimation method based on Kullback-Leibler divergence of survival functions (KLS), measuring the distance between an empirical and prescribed survival functions, has been used to estimate the parameter of Lindley distribution. The simulation studies have been carried out to compare the performance of the proposed estimator with the corresponding Least square (LS), Maximum likelihood (ML) and Maximum product spacing (MPS) methods of estimation.
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Ling, Jingxiu, Long Cheng, Xin Tong, and Zhihong Wu. "Research on rock breaking mechanism and load characteristics of TBM cutter based on discrete element method." Advances in Mechanical Engineering 13, no. 2 (February 2021): 168781402199883. http://dx.doi.org/10.1177/1687814021998831.
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Tunnel boring machine (TBM) is a large-scale tunnel engineering equipment, which has unparalleled advantages in safety and work efficiency. The cutter is subjected to complex and variable random impact loads, resulting in damage to bearings, cutter rings, and cutter shafts. Therefore, based on the discrete element simulation platform and experiment, this paper established the cutter rock simulation model based on the experimental data, and analyzed the rock breaking process, cutter load magnitude, and variation law. The research results show that when the cutter pole diameter decreases from 200 mm, 100 mm, and 0 mm in sequence, the rolling force increases accordingly, and the maximum increase of the rolling force is 56%. Meanwhile the lateral force decreases and the maximum average decrease value is 26%. Moreover, the rolling force showed a downward trend with the increase of the cutter spacing. When the cutter spacing is increased from 80 mm to 120 mm, the average rolling force decreases by 51%, and the maximum value rises slightly, increasing by 2%. And, the lateral force tends to increase, with an increase of 17% and the maximum lateral force value increase was 29%. The results can provide load input reference for TBM cutter layout, cutterhead structure design, and performance evaluation.
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Aritonang, Ririn Vionica, and Nurmaidah Nurmaidah. "Pengaruh Variasi Jarak Tulangan Sengkang Spiral Terhadap Kuat Lentur Balok Beton Bertulang." Jurnal PenSil 9, no. 3 (September 26, 2020): 188–95. http://dx.doi.org/10.21009/jpensil.v9i3.17080.
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This study aimed to determine the flexural strength of rectangular reinforced concrete beams by varying the concrete's spiral spacing. Test objects used dimensional beam 15 × 15 × 60 cm with a total of 20 samples, each variation made from 5 samples. The variation in spiral spacing without reinforcement was 2,5 cm, 5 cm, and 10 cm. The concrete quality plan used FC 30 MPa. Based on the analysis results noted that at a maximum flex load of 47.54 kN and a maximum bending moment of 3.579 kNm, the maximum bending load of 37.8 kN and a maximum bending moment of 2.849 kNm, and a maximum bending moment of 33.26 kN and A maximum of flexible paces of 2.508 kNm for every variation in the distance of the spiral. Based on the hypothesis test using a regression analysis method, the equation obtained was Y = 3,749 -13, 213X. The variation in the spiral spacing of reinforced concrete beams had no significant effect. The crack pattern that occurred on all test objects was generally a bending pattern and subjected to vertical cracks in the 1/3 portion of the beam's pull towards the press area.
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Huang, Qin, and J. Angelier. "Fracture spacing and its relation to bed thickness." Geological Magazine 126, no. 4 (July 1989): 355–62. http://dx.doi.org/10.1017/s0016756800006555.
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AbstractUsing examples from the Gulf of Suez and southeastern France, the distribution of tension tectonic joints as well as shear tectonic joints in continuous profiles is shown to fit a Gamma distribution. The parameters of this distribution are determined using the maximum likelihood method. Apparent fit with negative exponential distribution in photointerpretation analysis results from lack of resolution. The average joint spacing is directly proportional to bed thickness; it decreases when the degree of rock consolidation increases.
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Hu, H. R., C. Zhang, and X. Wang. "Numerical acoustic simulation of flow around circular cylinders based on Lattice Boltzmann method and Ffowcs Williams-Hawkings acoustic equation." International Journal of Computational Materials Science and Engineering 07, no. 01n02 (June 2018): 1850010. http://dx.doi.org/10.1142/s2047684118500100.
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Based on the GPU acceleration technique, Lattice Boltzmann method (LBM) and Ffowcs Williams-Hawkings (FW-H) acoustic equation are adopted to simulate the noise generated by flow around fixed and rotating circular cylinders when Reynolds number (Re) is 200. The results show that the sound pressure level has a peak in the vertical direction and it is higher than that in the streamwise direction. The maximum sound pressure level is significantly reduced when the cylinder rotates due to the suppression of vortex shedding compared to the case of a fixed cylinder. For tandem cylinders, the maximum sound pressure level in the vertical direction increases as the spacing ratio increases, and for parallel cylinders, it decreases as the spacing ratio increases. In addition, when using graphic processing unit (GPU), the computational efficiency is improved greatly and the speed-up reaches nearly 100.
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Mao, Wei, Hong Bing Jia, Dong Xu Yu, and Peng Ju Du. "Application and Study on Nonlinear Percolation Area Distribution Range Calculation Method in the Low Permeability Reservoir." Advanced Materials Research 962-965 (June 2014): 905–9. http://dx.doi.org/10.4028/www.scientific.net/amr.962-965.905.
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Based on the minimum start-up pressure gradient have been obtained from experiment, and the relationship between the minimum starting pressure gradient with maximum starting pressure gradient and the throat radius, first put forward the calculating the limit shear stress, then calculating the maximum starting pressure gradient method. Non-linear seepage corresponding to the pressure gradient range are obtained by regression analysis, nonlinear seepage flow in low permeability reservoir distribution area can be derived. Two well group examples of the Bei301 block of Hailaer oilfield, shows that calculating the method of nonlinear seepage flow area is available, and the results can reflect the symmetry oil well production performance, this method has application value. The On the basis of the formula of pressure gradient between oil wells and injection wells, New method to calculate the limit injection production well spacing is proposed. It is of importance for injection production well spacing in oilfield development plan.
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WANG, Y. B. "ESTIMATION OF THE DISTANCE BETWEEN STATIONS OF OVERTAKING TRAINS WHEN ORGANIZING A MIXED HIGH-SPEED, PASSENGER AND FREIGHT TRAFFIC ON A RAILWAY LINE." Transport systems and transportation technologies, no. 21 (August 15, 2021): 5. http://dx.doi.org/10.15802/tstt2021/237619.
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Purpose. This paper presents the calculation method and result of reasonable station spacing in the organization of mixed high-speed passenger and freight transportation, at different speed combinations and different types of train schedules.
Methodology. By using the principle of the shortest distance between stations, this paper analyzes the possible layout of passenger and freight trains running at different speeds between Brest and Moscow, and work out the optimal distance between overtaking stations. According to the shortest distance between stations, the blocking method with four-digit automatic should be used when the maximum speed of the passenger train is 250 km/h. The crossing scheme for different types of trains is determined, and the train schedule period (TDS) of each scheme is determined. Calculate the appropriate distance between stations that had been passed through with different trip intervals according to the characteristics of the passing passenger and freight trains. By adopting simulation analysis, the influence of different number of trains and their composition on the station spacing is simulated to work out the reasonable railway station spacing for passenger and freight train with a speed of 250 km / h.
Findings. In the case of passenger and freight traffic with the speed of 250 km / h, the optimal distance for stations between Brest and Moscow should be around 35 km. In order to make effective use of the existing infrastructure and achieve maximum transit capacity of the railway, it is recommended to increase the speed of the low priority trains.
Originality. The distance between stations on a line will affect the number of stations on the entire line, as well as the maximum train speed and the number of train pairs. Excessive or insufficient station spacing will affect the transportation capacity and efficiency. Therefore, reasonable station spacing will determine the number of trains and the maximum speed of each train for both passenger and freight.
Practical value. This paper proposes a method to estimate the reasonable spacing between crossing stations, which can ensure the effective utilization of the capacity of railway sections when high speed passenger trains on existing lines are running at speeds of up to 250 km/h.
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Ledezma, G., A. M. Morega, and A. Bejan. "Optimal Spacing Between Pin Fins With Impinging Flow." Journal of Heat Transfer 118, no. 3 (August 1, 1996): 570–77. http://dx.doi.org/10.1115/1.2822670.
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This is an experimental numerical and theoretical study of the heat transfer on a pin-finned plate exposed to an impinging air stream. The pin fins are aligned with the air approach velocity. The base plate and the fin cross section are square. It is demonstrated experimentally that the thermal conductance between the plate and the air stream can be maximized by selecting the fin-to-fin spacing S. Next, a simplified numerical model is used to generate a large number of optimal spacing and maximum heat transfer data for various configurations, which differ with respect to fin length (H), fin thickness (D), base plate size (L), fluid type (Pr), and air velocity (ReL). Finally, the behavior of the optimal spacing data is explained and correlated theoretically based on the intersection of asymptotes method. The recommended correlations for optimal spacing, Sopt/L ≅ 0.81 Pr−0.25 ReL−0.32, and maximum thermal conductance, (q/ΔT)max/kaH ≅ 1.57 Pr0.45 ReL0.69 (L/D)0.31, cover the range D/L = 0.06 − 0.14, H/L = 0.28−0.56, Pr = 0.72−7, ReD = 10−700, and ReL = 90−6000.
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Manzoor, Raheela, Asma Khalid, Ilyas Khan, Shams-Ul-Islam, Dumitru Baleanu, and Kottakkaran Sooppy Nisar. "Numerical Simulation of Drag Reduction on a Square Rod Detached with Two Control Rods at Various Gap Spacing via Lattice Boltzmann Method." Symmetry 12, no. 3 (March 18, 2020): 475. http://dx.doi.org/10.3390/sym12030475.
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Numerical simulations are performed to examine the effect of size of control rods (d1) and spacing ratio (g) on flow around a square rod with upstream and downstream control rods aligned in-line using the lattice Boltzmann method (LBM). The Reynolds number (Re) is fixed at Re = 160, while the spacing between the main rod and control rods is taken in the range 1 ≤ g ≤ 5 and the size of the control rod is varied between 4 and 20. Seven different types of flow mods are observed in this study at different values of g and d1. Variation in force statistics, like mean drag coefficient (Cdmean), Strouhal number (St), root mean square values of drag (Cdrms) and lift coefficients (Clrms), and percentage reduction in mean drag coefficient is discussed in detail. It was examined that vortex shedding completely suppressed at (g, d1) = (1, 12), (2, 12), and (2, 16) where steady flow mode exists. Moreover, it was found that at large gap spacing, where g = 5, the effect of control rods on the main rod vanishes. Due to this strong vortex shedding produced and as a result, maximum value of Cdmean is found at (g, d1) = (5, 8). The negative values of mean drag force are also observed at some gap spacing and size of control rods are due to the effect of thrust. Furthermore, the maximum percentage reduction in Cdmean is 121%, found at (g, d1) = (2, 20).
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Baryła, Anna, and Romuald Żmuda. "Determining the spacing of ridge terraces on arable land in central and south-western Poland." Annals of Warsaw University of Life Sciences – SGGW. Land Reclamation 49, no. 2 (June 1, 2017): 57–68. http://dx.doi.org/10.1515/sggw-2017-0005.
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Abstract The practice of many countries has shown that terraces can significantly prevent land degradation processes such as excessive soil erosion, landslides. Condition is good layout, proper construction, and then proper maintenance. Practical application in many countries showed that terraces can significantly prevent processes leading to the degradation of land, such as the excessive erosion of soils and landslides. The requirement for this is well-planned, adequate construction, and later – proper conservation. In Poland this is a little popular method. In the article, the dorsal spacing terraces were calculated for two catchments – in the central and south-western parts of Poland. Meteorological and soil data were used for Puczniew station (Ner catchment) and Boleścin station (Mielnica catchment). Kolmogorov–Smirnov test was performed to assess the compatibility of a given feature with a normal distribution, then the distribution of the probability distribution was developed. For probability 1, 50 and 90% the spacing of terraces was calculated using Ramser and Morgan method. The results obtained were combined with the results from the USLE model. Hydraulic methods have shown greater spacing for the Mielnica catchment (loess soils) compared to the Ner basin (clay loam). For the USLE model, the larger spacing was calculated for the Ner basin. From the practical application to the acceptance of land user will be the maximum distance calculated by different methods. The highest terrace spacing values were obtained using the Morgan method for the Mielnica catchment, for the Ner catchment model USLE.
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Almetwally, Ehab Mohamed, and Hisham Mohamed Almongy. "Maximum Product Spacing and Bayesian Method for Parameter Estimation for Generalized Power Weibull Distribution Under Censoring Scheme." Journal of Data Science 17, no. 2 (February 24, 2021): 407–44. http://dx.doi.org/10.6339/jds.201904_17(2).0010.
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Ren, Shuo, Jian Xing Wu, and Jian Zhong Li. "Relationship Study between Bolt Shape and Anchor Performance." Applied Mechanics and Materials 670-671 (October 2014): 1050–54. http://dx.doi.org/10.4028/www.scientific.net/amm.670-671.1050.
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Relationship between bolt rib type, rib height, rib spacing and anchor performance have been studied through laboratory drawing test method. Bolt rib type plays a significant impact on the bolt anchor performance. The bigger of the bolt rib height and higher of the drawing force, the better of the anchor performance, but when the rib reach a certain height, drawing force will not increase obvious with the continue increase of rib height. Drawing force will different if the rib spacing is different, and with the increase of rib spacing, drawing force will increase at first and then reduce. When the rib spacing is about 30mm, the drawing force will get the maximum and the best of the anchor performance.
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Jin, D. Y., R. X. Hu, W. R. Zhang, D. Lu, Q. Fu, and Y. J. Zhang. "Novel Emitter-Segmented Power HBT with 2-D Non-Uniform Segment Spacing for High Thermal Stability." Applied Mechanics and Materials 313-314 (March 2013): 737–41. http://dx.doi.org/10.4028/www.scientific.net/amm.313-314.737.
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With the aid of the thermal model, thermal resistance matrix of emitter-segmented power HBT is proposed to represent thermal effects. The effect of 2-dimensional (2-D) inter-segment spacing on thermal stability of device is studied. It is shown that the increase of inter-segment spacing could effectively decrease thermal coupling resistance, lower temperature of center segments, and hence improves the thermal stability. Furthermore, a novel emitter-segmented power HBT with 2-D non-uniform segment spacing is proposed, in which the non-uniformity of segment temperature is improved by 75.26% and the maximum power level difference of emitter segment is improved by 55.84%, when compared with uniform segment spacing HBT. Therefore the technique of 2-D non-uniform segment spacing is a better method for enhancing the thermal stability of power HBTs.
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Saucier, François, Richard Pleau, and Daniel Vézina. "Precision of the air void characteristics measurement by ASTM C 457: results of an interlaboratory test program." Canadian Journal of Civil Engineering 23, no. 5 (October 1, 1996): 1118–28. http://dx.doi.org/10.1139/l96-919.
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Since 1993, the Quebec Department of Transportation requires all its concrete suppliers to demonstrate that their concrete satisfies the requirements of the CSA A23.1 standard as regards the maximum spacing factor of the air void system. This new requirement raises questions about the reproducibility of the ASTM C 457 test method. An interlaboratory study was carried out to verify if the variability of the test method is sufficiently low to allow reliable decisions on the acceptance or rejection of in-place hardened concrete. A total of 18 operators from 13 different laboratories microscopically examined the six concrete slabs used for the study. It is concluded that the average reproducibility coefficient of variation is 14.4% for the total air content measurement and 14.2% for the spacing factor measurement. Considering these results, the probability that the measured value of the spacing factor exceeds the mandatory limit of 230 μm on a concrete production containing an air void system with a spacing factor of 170 μm (the target value proposed in the CSA A23.1 M-94 standard) is less than 0.7% (a probability of error of about 1%, 5%, or 10% is typical of most quality control test methods). Key words: concrete, air content, air void measurement, spacing factor, ASTM C 457 standard, interlaboratory study, freeze–thaw durability.
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Dodson, A., and D. C. Joy. "Fast Fourier Transform Techniques for Measuring SEM Resolution." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 1 (August 12, 1990): 406–7. http://dx.doi.org/10.1017/s0424820100180781.
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Precise knowledge of a particular SEM's resolution is important for at least two reasons to the microscopist operating the instrument. First, accurate interpretation of micrographs obtained in the course of daily operation depends on knowing the performance limits of the instrument. Second, it is important for the microscopist to be able to verify instrumental performance.Spatial resolution is typically determined using micrographs of materials containing structures having a “known” spacing. By showing that two objects in the micrograph are separated by some distance, it is claimed that the instrument is capable of resolving this spacing. This method is passable for instruments whose maximum resolution resolves only features of known spacing. However, for High Resolution SEM's (HRSEM) this method is not adequate. It is difficult to identify specimens with surface structure that can be verified to exist at the ultimate limits of today's HRSEM resolution. The fact that verifying resolution by this method depends on being able to verify the spacing of surface structure on a particular specimen leads to an interesting paradox - the resolution of a given instrument can be verified only after a better instrument is available to characterize the structure spacing.
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Aldahlan, Maha A. D., and Ahmed Z. Afify. "The Odd Exponentiated Half-Logistic Exponential Distribution: Estimation Methods and Application to Engineering Data." Mathematics 8, no. 10 (October 1, 2020): 1684. http://dx.doi.org/10.3390/math8101684.
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In this paper, we studied the problem of estimating the odd exponentiated half-logistic exponential (OEHLE) parameters using several frequentist estimation methods. Parameter estimation provides a guideline for choosing the best method of estimation for the model parameters, which would be very important for reliability engineers and applied statisticians. We considered eight estimation methods, called maximum likelihood, maximum product of spacing, least squares, Cramér–von Mises, weighted least squares, percentiles, Anderson–Darling, and right-tail Anderson–Darling for estimating its parameters. The finite sample properties of the parameter estimates are discussed using Monte Carlo simulations. In order to obtain the ordering performance of these estimators, we considered the partial and overall ranks of different estimation methods for all parameter combinations. The results illustrate that all classical estimators perform very well and their performance ordering, based on overall ranks, from best to worst, is the maximum product of spacing, maximum likelihood, Anderson–Darling, percentiles, weighted least squares, least squares, right-tail Anderson–Darling, and Cramér–von-Mises estimators for all the studied cases. Finally, the practical importance of the OEHLE model was illustrated by analysing a real data set, proving that the OEHLE distribution can perform better than some well known existing extensions of the exponential distribution.
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Basheer Sheeba, Jinshah, and Ajith Krishnan Rohini. "Structural and Thermal Analysis of Asphalt Solar Collector Using Finite Element Method." Journal of Energy 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/602087.
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The collection of solar energy using asphalt pavements has got a wide importance in the present energy scenario. Asphalt pavements subjected to solar radiation can reach temperature up to 70°C because of their excellent heat absorbing property. Many working parameters, such as pipe diameter, pipe spacing, pipe depth, pipe arrangement, and flow rate, influence the performance of asphalt solar collector. Existing literature on thermal energy extraction from asphalt pavements is based on the small scale laboratory samples and numerical simulations. In order to design an efficient asphalt solar collector there should be a payoff between the thermal and structural stability of the pavement, so that maximum heat can be absorbed without structural damage due to external load condition. This paper presents a combined thermal and structural analysis of asphalt solar collector using finite element method. Analysis is carried out in different models so as to obtain optimum pipe spacing, pipe diameter, depth, and pipe arrangement under the specified condition.
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Hashimoto, Hiromu, and Yasuhisa Hattori. "Improvement of the Static and Dynamic Characteristics of Magnetic Head Sliders by Optimum Design." Journal of Tribology 122, no. 1 (July 6, 1999): 280–87. http://dx.doi.org/10.1115/1.555372.
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The aim of this paper is to develop a general methodology for the optimum design of magnetic head sliders in improving the spacing characteristics between a slider and disk surface under static and dynamic operating conditions of hard disk drives and to present an application of the methodology to the IBM 3380-type slider design. To generate the optimal design variables, the objective function is defined as the weighted sum of the minimum spacing, the maximum difference in the spacing due to variation of the radial location of the head, and the maximum amplitude ratio of the slider motion. Slider rail width, taper length, taper angle, suspension position, and preload are selected as the design variables. Before the optimization of the head, the effects of these five design variables on the objective function are examined by a parametric study, and then the optimum design variables are determined by applying the hybrid optimization technique, combining the direct search method and successive quadratic programming. From the obtained results, the effectiveness of optimum design on the spacing characteristics of magnetic heads is clarified. [S0742-4787(00)03701-2]
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Tamoradi, Zeinab, Javad Ahadiyan, Mohsen Najarchi, Houshang Hasounizadeh, and Mohammad Mahdi Najafizadeh. "Reducing bend scour using in-phase and out-of-phase hydraulic jets." Water Supply 19, no. 5 (January 22, 2019): 1446–53. http://dx.doi.org/10.2166/ws.2019.014.
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Abstract This study investigated the effectiveness of a new method of reducing scour in river bends. In this method, a perforated tube was placed along the bend on the bed and water and air were separately injected into the bend flow from both ends of the tube. The goal was to make a water and air screen to block secondary flows and prevent them from reaching the outer bank. The air jet and water jet injection modes changed the location of maximum scour depth from the outer wall to the middle of the bend, which increased the navigable width. Increasing the spacing between tube ports decreased the maximum scour depth. A port spacing of 5 cm was determined to be the optimal amount. At a bend section of 90°, the decrease in maximum scour depth was estimated to be 85% and 91% under air jet injection (qa/Q = 2.74) and water jet injection (qw/Q = 0.17), respectively. At 170°, the decrease in maximum scour depth was 79% and 86% for the air jet and water jet, respectively. The results show that the optimal effect was obtained by water jet injection.
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Lamb, J. F. S., L. D. Johnson, D. K. Barnes, and J. J. Marquez-Ortiz. "A method to characterize root morphology traits in alfalfa." Canadian Journal of Plant Science 80, no. 1 (January 1, 2000): 97–104. http://dx.doi.org/10.4141/p98-124.
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Productivity in alfalfa (Medicago sativa L.) has been shown to be influenced by root morphology. Our objectives were to identify the optimum age, cultural practices, and environmental conditions to characterize taproot diameter (TD), lateral root number (LRN), fibrous root mass (FRM), and determinate taproot percentage (DTP) in alfalfa. No correlations were found between greenhouse-cultured plants and 21-wk-old field-grown plants for LRN or FRM, while TD showed low to moderate correlations between greenhouse and field environments. Fourfold more plants with determinate taproots were identified in transplanted plots compared to seeded plots. All root traits were affected by plant spacing but, no germplasm × plant spacing interactions were found. Solid seeded plants needed more time to show maximum expression of root traits and scored lower for LRN and FRM and had smaller TD than spaced plants. Only TD had a significant germplasm × location interaction. Both TD and LRN increased with N fertilizer and between the seeding and first production years, but no germplasm × N rate or germplasm × year interactions were found. Rankings of alfalfa germplasms were the same at the end of the seeding year (22 wk after planting) and at the end of the first production year (74 wk after planting). Characterization of LRN and FRM in alfalfa should be conducted in seeded field plots with uniform plant spacing at one location, with or without N fertilizer at least 22 wk after planting. A similar protocol with evaluation at more than one location would be more appropriate for characterization of TD. Key words: Medicago sativa L., root morphology, alfalfa
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Loov, Robert E. "Review of A23.3-94 simplified method of shear design and comparison with results using shear friction." Canadian Journal of Civil Engineering 25, no. 3 (June 1, 1998): 437–50. http://dx.doi.org/10.1139/l97-101.
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A review of the so-called simplified method of shear design described in CSA A23.3-94 "Design of concrete structures" shows that the method is not simple. The designer is required to check numerous equations and limits. The resulting relation between stirrup spacing and shear strength is found to be an extremely complex line resulting from the intersection of seven separate surfaces. A shear friction model has been developed which seems to predict the shear strength of beams rather well. Stirrups and longitudinal reinforcement provide a clamping force thereby increasing the friction force which can be transferred across a crack along a potential failure plane. This model is based on the shear strength after cracking so that no diagonal tension strength is included. The shear friction model has been used as the basis for determining approximate equations for maximum stirrup spacing. A comparison of these approximate shear friction predictions with those using the simplified method indicates a high degree of correlation but many important differences. It seems that shear design can be clarified as well as simplified by adoption of the shear friction approach.Key words: reinforced concrete, shear, shear friction, shear tests, stirrup spacing.
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Bantan, Rashad, Amal S. Hassan, Mahmoud Elsehetry, and B. M. Golam Kibria. "Half-Logistic Xgamma Distribution: Properties and Estimation under Censored Samples." Discrete Dynamics in Nature and Society 2020 (June 17, 2020): 1–18. http://dx.doi.org/10.1155/2020/9136513.
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This paper proposed a new probability distribution, namely, the half-logistic xgamma (HLXG) distribution. Various statistical properties, such as, moments, incomplete moments, mean residual life, and stochastic ordering of the proposed distribution, are discussed. Parameter estimation of the half-logistic xgamma distribution is approached by the maximum likelihood method based on complete and censored samples. Asymptotic confidence intervals of model parameters are provided. A simulation study is conducted to illustrate the theoretical results. Moreover, the model parameters of the HLXG distribution are estimated by using the maximum likelihood, least square, maximum product spacing, percentile, and Cramer–von Mises (CVM) methods. Superiority of the new model over some existing distributions is illustrated through three real data sets.
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Almongy, Hisham M., Ehab M. Almetwally, Randa Alharbi, Dalia Alnagar, E. H. Hafez, and Marwa M. Mohie El-Din. "The Weibull Generalized Exponential Distribution with Censored Sample: Estimation and Application on Real Data." Complexity 2021 (February 26, 2021): 1–15. http://dx.doi.org/10.1155/2021/6653534.
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This paper is concerned with the estimation of the Weibull generalized exponential distribution (WGED) parameters based on the adaptive Type-II progressive (ATIIP) censored sample. Maximum likelihood estimation (MLE), maximum product spacing (MPS), and Bayesian estimation based on Markov chain Monte Carlo (MCMC) methods have been determined to find the best estimation method. The Monte Carlo simulation is used to compare the three methods of estimation based on the ATIIP-censored sample, and also, we made a bootstrap confidence interval estimation. We will analyze data related to the distribution about single carbon fiber and electrical data as real data cases to show how the schemes work in practice.
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Badowich, Connor, Jacques Rousseau, and Loïc Markley. "Convex optimization of coil spacing in cascaded multi-coil wireless power transfer." Wireless Power Transfer 7, no. 1 (February 19, 2020): 42–50. http://dx.doi.org/10.1017/wpt.2020.5.
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AbstractIn this paper, we use convex optimization to maximize power efficiency through cascaded multi-coil wireless power transfer systems and investigate the resulting characteristic spacing. We show that although the efficiency is generally a non-convex function of the coil spacing, it can be approximated by a convex function when the effects of higher-order couplings are small. We present a method to optimize the spacing of cascaded coils for maximum efficiency by perturbing the solution of the convex approximation to account for higher-order interactions. The method relies on two consecutive applications of a local optimization algorithm in order to enable fast convergence to the global optimum. We present the optimal configurations of coil systems containing up to 20 identical coils that transfer power over distances up to 4.0 m. We show that when spacing alone is optimized, there exist an optimal number of coils that maximize transfer efficiency across a given distance. We also demonstrate the use of this method in optimizing the placement of a select number of high-Q coils within a system of low-Q relay coils, with the highest efficiencies occurring when the high-Q coils are placed on either side of the largest gaps within the relay coil chain.
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Qiao, Xiaoshi, Shizhang Wang, Craig S. Schwartz, Zhiquan Liu, and Jinzhong Min. "A Method for Probability Matching Based on the Ensemble Maximum for Quantitative Precipitation Forecasts." Monthly Weather Review 148, no. 8 (July 24, 2020): 3379–96. http://dx.doi.org/10.1175/mwr-d-20-0003.1.
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Abstract A probability matching (PM) product using the ensemble maximum (EnMax) as the basis for spatial reassignment was developed. This PM product was called the PM max and its localized version was called the local PM (LPM) max. Both products were generated from a 10-member ensemble with 3-km horizontal grid spacing and evaluated over 364 36-h forecasts in terms of the fractions skill score. Performances of the PM max and LPM max were compared to those of the traditional PM mean and LPM mean, which both used the ensemble mean (EnMean) as the basis for spatial reassignment. Compared to observations, the PM max typically outperformed the PM mean for precipitation rates ≥5 mm h−1; this improvement was related to the EnMax, which had better spatial placement than the EnMean for heavy precipitation. However, the PM mean produced better forecasts than the PM max for lighter precipitation. It appears that the global reassignment used to produce the PM max was responsible for its poorer performance relative to the PM mean at light precipitation rates, as the LPM max was more skillful than the LPM mean at all thresholds. These results suggest promise for PM products based on the EnMax, especially for rare events and ensembles with insufficient spread.
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Zhang, Y. O., T. Zhang, H. Ouyang, and T. Y. Li. "SPH Simulation of Acoustic Waves: Effects of Frequency, Sound Pressure, and Particle Spacing." Mathematical Problems in Engineering 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/348314.
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Acoustic problems consisting of multiphase systems or with deformable boundaries are difficult to describe using mesh-based methods, while the meshfree, Lagrangian smoothed particle hydrodynamics (SPH) method can handle such complicated problems. In this paper, after solving linearized acoustic equations with the standard SPH theory, the feasibility of the SPH method in simulating sound propagation in the time domain is validated. The effects of sound frequency, maximum sound pressure amplitude, and particle spacing on numerical error and time cost are then subsequently discussed based on the sound propagation simulation. The discussion based on a limited range of frequency and sound pressure demonstrates that the rising of sound frequency increases simulation error, and the increase is nonlinear, whereas the rising sound pressure has limited effects on the error. In addition, decreasing the particle spacing reduces the numerical error, while simultaneously increasing the CPU time. The trend of both changes is close to linear on a logarithmic scale.
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Han, Weige, Zhendong Cui, and Zhengguo Zhu. "The Effect of Perforation Spacing on the Variation of Stress Shadow." Energies 14, no. 13 (July 4, 2021): 4040. http://dx.doi.org/10.3390/en14134040.
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When the shale gas reservoir is fractured, stress shadows can cause reorientation of hydraulic fractures and affect the complexity. To reveal the variation of stress shadow with perforation spacing, the numerical model between different perforation spacing was simulated by the extended finite element method (XFEM). The variation of stress shadows was analyzed from the stress of two perforation centers, the fracture path, and the ratio of fracture length to spacing. The simulations showed that the reservoir rock at the two perforation centers is always in a state of compressive stress, and the smaller the perforation spacing, the higher the maximum compressive stress. Moreover, the compressive stress value can directly reflect the size of the stress shadow effect, which changes with the fracture propagation. When the fracture length extends to 2.5 times the perforation spacing, the stress shadow effect is the strongest. In addition, small perforation spacing leads to backward-spreading of hydraulic fractures, and the smaller the perforation spacing, the greater the deflection degree of hydraulic fractures. Additionally, the deflection angle of the fracture decreases with the expansion of the fracture. Furthermore, the perforation spacing has an important influence on the initiation pressure, and the smaller the perforation spacing, the greater the initiation pressure. At the same time, there is also a perforation spacing which minimizes the initiation pressure. However, when the perforation spacing increases to a certain value (the result of this work is about 14 m), the initiation pressure will not change. This study will be useful in guiding the design of programs in simultaneous fracturing.
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Li, Xin-kai, Wei Liu, Ting-jun Zhang, Pei-ming Wang, and Xiao-dong Wang. "Analysis of the Effect of Vortex Generator Spacing on Boundary Layer Flow Separation Control." Applied Sciences 9, no. 24 (December 13, 2019): 5495. http://dx.doi.org/10.3390/app9245495.
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During the operation of wind turbines, flow separation appears at the blade roots, which reduces the aerodynamic efficiency of the wind turbine. In order to effectively apply vortex generators (VGs) to blade flow control, the effect of the VG spacing (λ) on flow control is studied via numerical calculations and wind tunnel experiments. First, the large eddy simulation (LES) method was used to calculate the flow separation in the boundary layer of a flat plate under an adverse pressure gradient. The large-scale coherent structure of the boundary layer separation and its evolution process in the turbulent flow field were analyzed, and the effect of different VG spacings on suppressing the boundary layer separation were compared based on the distance between vortex cores, the fluid kinetic energy in the boundary layer, and the pressure loss coefficient. Then, the DU93-W-210 airfoil was taken as the research object, and wind tunnel experiments were performed to study the effect of the VG spacing on the lift–drag characteristics of the airfoil. It was found that when the VG spacing was λ/H = 5 (H represents the VG’s height), the distance between vortex cores and the vortex core radius were approximately equal, which was more beneficial for flow control. The fluid kinetic energy in the boundary layer was basically inversely proportional to the VG spacing. However, if the spacing was too small, the vortex was further away from the wall, which was not conducive to flow control. The wind tunnel experimental results demonstrated that the stall angle-of-attack (AoA) of the airfoil with the VGs increased by 10° compared to that of the airfoil without VGs. When the VG spacing was λ/H = 5, the maximum lift coefficient of the airfoil with VGs increased by 48.77% compared to that of the airfoil without VGs, the drag coefficient decreased by 83.28%, and the lift-to-drag ratio increased by 821.86%.
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Wang, Shen, Hani Mitri, Huamin Li, Dongyin Li, and Wen Wang. "Study of SCA-Induced Rock Crack Propagation under Different Stress Conditions Using a Modified Cohesive Element Method." Advances in Civil Engineering 2018 (November 1, 2018): 1–16. http://dx.doi.org/10.1155/2018/7936043.
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When inducing cracks, soundless cracking agents (SCAs) do not generate vibration, harmful gas, dust, nor flying rock fragment, making them suitable for hard rock roof breaking, rock burst prevention, oil or gas reservoir stimulation, and building demolition. In this study, SCA-induced crack initiation and propagation in different stress conditions were modelled using a modified cohesive element method. A new traction-separation law for describing rock compressive shear strength was proposed. The crack length and direction in bidirectional isobaric and unequal stress fields were analyzed in detail. The crack initiation pressure and the incremental ratio of crack length to SCA expansion pressure were proposed as two indicators to evaluate the difficulty in rock breaking in deep underground. Results indicate that (1) the modified cohesive element method used in this study is feasible to model crack propagation in deep rocks; (2) the maximum expansion pressure of SCAs depends on rock elastic modulus and geostress field and should be measured under a condition similar to deep underground prior to SCA borehole spacing design; when using the SCAs with a maximum expansion pressure of 100 MPa in 600 m underground, the suggested borehole spacing is less than 220 mm; and (3) σ3 dominates the crack initiation pressure while the principal stress ratio σ3/σ1 and notch direction control the direction of crack propagation.
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Mokhov, E. N., A. D. Roenkov, and A. S. Segal. "SiC Sublimation Growth at Small Spacing between Source and Seed." Materials Science Forum 740-742 (January 2013): 69–72. http://dx.doi.org/10.4028/www.scientific.net/msf.740-742.69.
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The growth kinetics of SiC crystals doped with Al and Ga impurities and grown by the sublimation sandwich method at a small spacing between the source and the seed (<1 mm) has been studied. Dependence of an Al-doped SiC crystals growth rate on the clearance is shown to be non-monotonic and exhibits maximum at the clearance about of 100-300 μm. Such dependence is also observed for growth of pure and Ga-doped SiC crystals but only on (0001)Si face. The derived dependencies suggest that there are some considerable kinetic limitations of the SiC growth rate. High quality SiC crystals with such high concentration of the Al impurity as 2x1021 cm-3 were grown.
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Viana, Anselmo Eloy Silveira, Abel Rebouças São José, Sylvana Naomi Matsumoto, and Sálvio Gusmão Sales-Júnior. "Estimation of optimum plot sizes in field experiments with annatto." Bragantia 61, no. 2 (August 2002): 181–85. http://dx.doi.org/10.1590/s0006-87052002000200011.
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The objective of this study was to estimate the optimum plots size for experiments with annatto. The uniformity assay consisted of 12 rows with 12 plants in each row. The variety Bico de Pato was used, planted in 5 x 4 m spacing and evaluated at 5 years of age. Three methods were used: maximum curvature, modified maximum curvature and the comparison of variances. The plot size estimate varied according to the methodology used and the characteristic analyzed. The adequate plot size was found to be 107.2 m² (5 plants) using the modified maximum curvature method, which resulted in more precise estimates , taking into consideration that the ideal plot should facilitate the efficient evaluation of all characteristics analyzed in this experiment.
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Sahoo, Smrutirekha, Bappaditya Manna, and K. G. Sharma. "Seismic Behaviour of Buried Pipelines: 3D Finite Element Approach." Journal of Earthquakes 2014 (August 5, 2014): 1–9. http://dx.doi.org/10.1155/2014/818923.
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This paper presents a numerical investigation on six pipeline models to study the seismic response of single and double buried pipelines using finite element method. Different depth and spacing of pipes are considered to investigate their prominent role in the seismic response of buried pipelines under an earthquake loading having PGA of 0.2468 g. In case of single pipeline, the maximum magnitude of final displacement as well as the stress at the end of the seismic sequence is found at the burial depth equal to the pipe diameter. In case of double pipeline, the maximum magnitude of final displacement is found when the spacing between pipes is equal to half the pipe diameter and there is an increasing tendency of developed stress with increase in spacing between pipes. In addition to the above results, the response of the buried pipelines with a particular bend angle (artificially induced bend/buckle) to the permanent ground deformation which is assumed to be the result of seismic wave propagation has also been studied. Remarkable differences in these results are obtained and with these results the designers can reduce seismic risk to their buried pipelines by taking proper precautionary measures.
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Chen, Haijun, Ning Wang, and Hongcai He. "Equivalent Circuit Analysis of Photovoltaic-Thermoelectric Hybrid Device with Different TE Module Structure." Advances in Condensed Matter Physics 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/824038.
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Combining two different types of solar cells with different absorption bands into a hybrid cell is a very useful method to improve the utilization efficiency of solar energy. The experimental data of dye-sensitized solar cells (DSSCs) and thermoelectric generators (TEG) was simulated by equivalent circuit method, and some parameters of DSSCs were obtained. Then, the equivalent circuit model with the obtained parameters was used to optimize the structure design of photovoltaic- (PV-) thermoelectric (TE) hybrid devices. The output power(Pout)first increases to a maximum and then decreases by increasing the TE prism size, and a smaller spacing between p-type prism and n-type prism of a TE p-n junction causes a higher output power of TEG and hybrid device. When the spacing between TE prisms is 15 μm and the optimal base side length of TE prism is 40 μm, the maximum theoretical efficiency reaches 24.6% according to the equivalent circuit analysis. This work would give some enlightenment for the development of high-performance PV-TE hybrid devices.
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Chen, Ying, Jing Xie, Shang Yue Shen, and Ping Jin. "Preparation of Epoxy Resin Composites by Chitosan Modified Montmorillonite." Advanced Materials Research 311-313 (August 2011): 113–16. http://dx.doi.org/10.4028/www.scientific.net/amr.311-313.113.
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OMMT was compounded by MMT and 1% (v/v) acetic acid dissolved chitosan via solution intercalate method, and then prepared the composites with epoxy resin. The change about spacing of montmorillonite was tested by XRD, and the molecular structure of OMMT was tested by Fourier infrared spectrum. The tensile strength and impact strength of epoxy resin composites were also tested. The result showed that the spacing of montmorillonite first increased then decreased along with the increasing mass fraction of chitosan. The maximum value (d001=1.983 nm) appeared when mass fraction of chitosan was 30%. And tensile strength and impact strength were improved by 86.8 and 51.2% respectively.
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Gu, Xiao Hua, Shi Wei Li, Bing Zheng, and Jia Liang Zhou. "Preparation and Research of Anionic and Cationic Secondary Modified Organophilic Montmorillonite." Advanced Materials Research 396-398 (November 2011): 417–20. http://dx.doi.org/10.4028/www.scientific.net/amr.396-398.417.
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A novel method is proposed to modify montmorillonite with anionic surfactants, cationic surfactants and halides stearyl cationic surfactants made by our group (Z-surfactant). The structure of organophilic montmorillonite (OMMT) was characterized by XRD and TG. The results of X-ray diffraction show that cationic surfactants and anionic surfactants are all intercalated into the layer of MMT. When modified with cationic surfactants, the interlayer spacing of MMT increases from 1.24 nm to the maximum of 3.76 nm. When it was secondary modified, the insertion order is to insert the cation first and then the anion. The interlayer spacing of montmorillonite increases to 4.80 nm, the modification effect is well.
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Pravdyva, L. A. "Photosynthetic activity of grain sorghum crops depending on the method of sowing seeds." Collected Works of Uman National University of Horticulture 1, no. 97 (December 28, 2020): 61–71. http://dx.doi.org/10.31395/2415-8240-2020-97-1-61-71.
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Grain sorghum is a drought-resistant crop and forms a high grain productivity and biomass as a raw material for the production of bioethanol and solid fuel in difficult soil and climatic conditions. The aim of the research was to establish the influence of sowing seeds method of the grain sorghum varieties on the photosynthetic activity of crops in the conditions of the Right-Bank Forest-Steppe of Ukraine. Methods. Field, laboratory, mathematical and statistical. Results. It has been proved that the leaf surface area of grain sorghum plants reached its maximum during the period of "throwing out panicles - flowering". It was the largest when sowing with a row spacing of 45 cm and at a plant density of 150 thousand units/ha – 34.8 thousand m2/ha for the Dniprovsky 39 variety and 32.7 thousand m2/ha for the Vinets variety. With the standing density of 200 thousand pieces/ha, the Dniprovsky 39 variety has 37.8 thousand m2/ha, the Vinets variety – 35.6 thousand m2/ha and with the density of 250 thousand pieces/ha, respectively 38.2 and 36.9 thousand m2/ha. The photosynthetic potential also changed depending on the size of the assimilation surface during the growing season. It was the highest when sowing seeds with a row spacing of 45 cm and amounted to 1.13–1.29 million m2/ha for the Dniprovsky 39 variety and 1.10–1.22 million m2/ha for the Vinets variety. When sowing with the row spacing of 15 cm, this indicator was 0.86–1.07 million m2/ha for the Dniprovsky 39 variety and 0.84–1.09 million m2/ha for the Vinets variety. When sowing grain sorghum seeds with the row spacing of 70 cm, the photosynthetic potential was 0.83–1.03 million m2/ha and 0.78–0.95 million m2/ha, respectively. An increase in the plant density from 150 to 250 thousand pieces/ha of grain sorghum contributed to an increase not only in the assimilation leaf surface, but also in the photosynthetic potential. The high net productivity of photosynthesis was observed when sowing seeds with the row spacing of 45 cm and for the Dniprovsky 39 variety it was in the range of 3.36–3.94 g/m2 per day, for the Vinets variety — 3.32–3.81 g/m2 in day. Conclusions. It was found that with a change in the feeding area of grain sorghum plants, the assimilation surface of leaves, photosynthetic potential and net productivity of photosynthesis change.
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Mitsuya, Yasunaga, and Yasuji Ohshima. "Error Analysis of Head-Disk Spacing Measurements Made by Using Optical Interferometry." Journal of Tribology 123, no. 2 (June 16, 2000): 358–63. http://dx.doi.org/10.1115/1.1308001.
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An analytical and simplified method was developed for predicting error propagation encountered when optically measuring head-to-medium spacing in magnetic disk drives. Two kinds of optical interferences observed between the flying head and the glass disk were considered. The first is the homodyne interferometry in which the spacing is obtained from light intensity variation due to interference. The second is polarization interferometry in which the spacing is determined from the phase difference between the parallel and perpendicular components of polarized light. To analytically predict the amount of error propagation, the interference intensity must be presented as a function of its maximum and minimum values which determine the calibration curve. For this purpose, two kinds of accurate and useful approximations were introduced; one is for homodyne interferometry and the other is for polarization interferometry. Using these approximations, the calibration curves were presented in terms of the detected signal and its extremum. Calculation examples were demonstrated for typical head-medium interface conditions and the contribution of error components to the error in spacing measurement was clarified.
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Ahmed, A., R. Manzoor, S. U. Islam, and H. Rahman. "Numerical investigation for flow over a square rod through a passive control method at various Reynolds numbers." Canadian Journal of Physics 98, no. 5 (May 2020): 425–32. http://dx.doi.org/10.1139/cjp-2019-0155.
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This work presents a numerical simulation performed to study the effect of Reynolds number (Re = 80–200) on fluid flow over a square rod attached to two small controlling rods using the Lattice Boltzmann method. For this reason, the spacing ratio between the control rods and main rod varies systematically from g = 0.5–5. Flow has been subdivided into three flow regimes based on spacing ratios. The first flow regime is considered at a small gap (g = 0.5, 1, and 1.5), the second flow regime is obtained at a moderate gap (g = 2, 2.5, and 3), and the third flow regime is considered a at large gap (g = 4–5). Five different types of flow modes were noticed in the given flow regimes. The values Re = 200 and g = 5 were found to be critical due to a sudden change in flow characteristics. The maximum value of Cdmean is 0.869 and the largest percent reduction (65.15%) in the mean drag coefficient was found at Re = 200 and g = 2.