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排序方式: 共有244条查询结果,搜索用时 18 毫秒
1.
Raw and heat processed peanut flours were found to contain higher in vitro trypsin inhibitor activity and lectin content than similarly processed soy flour. When fed to weanling rats at a level of 10% protein, the response pattern in food consumption, growth, liver function, and serum chemistries was not consistent among or between the groups. It is concluded that the levels of antinutritional factors in legumes do not correlate with their overall biological impact in feeding studies with the rat. 相似文献
2.
Experiment statistical method and genetic algorithms based optimization method are used to obtain the optimum differential gear ratio for heavy truck that provides best fuel consumption when changing the working condition that affects its torque and speed range. The aim of the study is to obtain the optimum differential gear ratio with fast and accurate optimization calculation without affecting drivability characteristics of the vehicle according to certain driving cycles that represent the new working conditions of the truck. The study is carried on a mining dump truck YT3621 with 9 forward shift manual transmission. Two loading conditions,no load and 40 t,and four on road real driving cycles have been discussed. The truck powertrain is modeled using GT-drive,and DOE-post processing tool of the GT-suite is used for DOE analysis and genetic algorithm optimization. 相似文献
3.
SHADAB?DABAGH ALI?A?ATI S?K?GHOSHAL SAMAD?ZARE R?M?ROSNAN AHMED?S?JBARA ZULKAFLI?OTHAMANEmail author 《Bulletin of Materials Science》2016,39(4):1029-1037
Cu–Al substituted Co ferrite nanopowders, Co1?x Cu x Fe2?x Al x O4 (0.0 ≤ x ≤ 0.8) were synthesized by the co-precipitation method. The effect of Cu–Al substitution on the structural and magnetic properties have been investigated. X-ray diffraction (XRD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM) and vibrating sample magnetometer (VSM) are used for studying the effect of variation in the Cu–Al substitution and its impact on particle size, magnetic properties such as M s and H c . Cu–Al substitution occurs and produce a secondary phase, α-Fe 2 O 3. The crystallite size of the powder calcined at 800 °C was in the range of 19–26 nm. The lattice parameter decreases with increasing Cu–Al content. The nanostructural features were examined by FESEM images. Infrared absorption (IR) spectra shows two vibrational bands; at around 600 (v 1) and 400 cm ?1 (v 2). They are attributed to the tetrahedral and octahedral group complexes of the spinel lattice, respectively. It was found that the physical and magnetic properties have changed with Cu–Al contents. The saturation magnetization decreases with the increase in Cu–Al substitution. The reduction of coercive force, saturation magnetization and magnetic moments are may be due to dilution of the magnetic interaction. 相似文献
4.
Tarek Uddin MOHAMMED Aziz Hasan MAHMOOD Mohammad Zunaied-Bin-HARUN Jamil Ahmed JOY Md. Asif AHMED 《Frontiers of Structural and Civil Engineering》2021,15(6):1400
Aggregates are the biggest contributor to concrete volume and are a crucial parameter in dictating its mechanical properties. As such, a detailed experimental investigation was carried out to evaluate the effect of sand-to-aggregate volume ratio (s/a) on the mechanical properties of concrete utilizing both destructive and non-destructive testing (employing UPV (ultrasonic pulse velocity) measurements). For investigation, standard cylindrical concrete samples were made with different s/a (0.36, 0.40, 0.44, 0.48, 0.52, and 0.56), cement content (340 and 450 kg/m3), water-to-cement ratio (0.45 and 0.50), and maximum aggregate size (12 and 19 mm). The effect of these design parameters on the 7, 14, and 28 d compressive strength, tensile strength, elastic modulus, and UPV of concrete were assessed. The careful analysis demonstrates that aggregate proportions and size need to be optimized for formulating mix designs; optimum ratios of s/a were found to be 0.40 and 0.44 for the maximum aggregate size of 12 and 19 mm, respectively, irrespective of the W/C (water-to-cement) and cement content. 相似文献
5.
M. S. AHMED 《International journal of systems science》2013,44(10):1577-1591
A novel approach to decentralized state estimation in a large-scale interconnected system is proposed. The method assumes a known model for the local subsystem only, and therefore is suitable when the other subsystem models and the interaction matrices are partially or totally unknown. An innovation representation suitable for decentralized subsystem state estimation is derived. The state estimation problem is then solved through the parametric identification of the innovation representation. The identification algorithm is based upon a pseudo-linear regression (PLR) principle that attempts minimization of the innovation variances. 相似文献
6.
This paper describes an on-line procedure for estimating the parameters of linear discrete time systems when input and output are subjected to measurement noise of unknown statistics. The algorithm is derived through stochastic approximation, To ensure unbiased parameter estimates, the correlated part of the residuals are first estimated by modelling the residuals as an autoregressive series, and then subtracted from the estimated residuals. The algorithm estimates the system parameters and noise parameters simultaneously. Three gain expressions are derived for the estimation algorithm. They are («) scalar gain, (b) diagonal matrix gain, and (c) square matrix gain. 相似文献
7.
In the present work, a general model of the equations of generalized thermoelasticity for a homogeneous isotropic elastic half-space solid whose surface is subjected to a mode-I crack problem under the effect of rotation is investigated. The normal mode analyses are used to obtain the expressions for the temperature distribution, the displacement component and thermal stresses in the context of the dual-phase-lag theory of thermoelasticity proposed by Tzou. The boundary of the crack is subjected to a prescribed stress distribution and temperature. Some particular cases are also discussed in the context of the problem. The numerical values of the temperature distribution, the displacement components and thermal stresses are also computed for a suitable material and the results are presented graphically. The effects of rotation, reinforcement and the phase lags parameters are discussed in detail in the light of earlier works. 相似文献
8.
AHMED FAROUK KAMAL 《International journal of remote sensing》2013,34(10):2109-2116
Abstract The Pleistocene ridges south-west of Alexandria are of marine origin and represent the ancient shoreline of the former sea levels. Several authors have described the nature, origin and geomorphology of the Pleistocene ridges. The objective is to delineate these ridges using aerial photomosaics at 1:100000 scale and a Landsat image at 1:250000 scale. The area is covered by beach sands in the northern part and consolidated limestone forming coastal ridges southwards. The lowlands between the ridges are occupied by marshes, lagoons or mixtures of clay and lime materials. Plant cover occurs in the central part. The different ridges recognized photogeologically are eight ridges and the foreshore ridges are more distinct than those of the backshore. Owing to the presence of plant cover, some ridges appear as faint lines. The ridges and lowlands appear on photomosaics with tonal contrast where successive light and dark toned areas can be easily identified. The interpreted ridges were correlated with those in the topographic map with the same scale and covering the same area. It was found that a number of these ridges follow the configuration of the relief where they are represented by high peaks. Ridges appear as elongated alignments nearly parallel with the Mediterranean Sea shore with a general trend NE-SW. The presence of some minerals such as augite and the size of their grains indicate that the sea currents and prevailing wind directions were coming mainly from the east or north-east whereas the reverse case occurs nowadays. Photointerpretation indicated the presence of a number of fractures trending NW-SE, dissecting the ridges in the northern part of the area. 相似文献
9.
AHMED S. ABUTALEB 《International journal of control》2013,86(5):1653-1670
This paper presents a modified Sridhar filter which is applied to the problem of the real-time estimation of the trajectory of a manoeuvring re-entry vehicle (MARV) from its radar observations. The Sridhar filter is based on optimal control concepts, specifically the Pontryagin minimum principle and the method of invariant imbedding. In this approach the unknown forces on the MARV are treated as controls that drive the MARV dynamics to track the noisy observed trajectory. This treatment differs from that used with the extended Kalman filter (EKF), where a new state vector of the unknown forces acting on the MARV considered as Wiener processes is augmented to the MARV state vector. The Sridhar filter does not increase the MARV state vector so its computational time, for the cases studied, is about 20% that of the EKF. The performance, as measured by the point error, of the proposed approach is even better than that of the conventional EKF. 相似文献
10.
In this paper the problem of selecting an optimal feedback controller, from a class of linear systems, for a non-linear dynamical system, is reduced to a standard parameter optimization problem given by Boltyanskii. A necessary condition for the selection of the optimal parameters is presented. 相似文献