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921.
Energy requirements of grazing livestock seem to be poorly defined. Requirements generated from measurements in pen-fed animals present both theoretical and practical concerns when they are applied to grazing situations. In mature ruminants a majority of energy used for maintenance seems to be consumed by visceral tissues. Moreover, factors that affect visceral energy use are poorly understood. Energy supplementation to meet requirements and production demands is often practiced during periods of summer dormancy and in winter months. Source of supplemental energy varies widely and includes grains, readily digestible fiber sources, and high-quality forages. Intake and digestibility can be reduced or unaffected by energy supplementation. In some cases, lower levels of energy supplementation have been shown to increase utilization of grazed forage. Reductions in ruminal pH, often cited as the major cause of reduced fiber digestion, may not always explain reductions in intake and digestibility associated with energy supplementation. Livestock production is usually either enhanced or unaffected by energy supplementation. Additional research regarding energy requirements of grazing ruminants, visceral energy use, and mechanisms associated with reductions in intake and digestibility of grazed forage resulting from energy supplementation is warranted. 相似文献
922.
A nonlinear finite element static analysis is used to predict the damage in rectangular/circular plates due to large deformation simulating low-velocity impact. The impact due to the ball impactor is modelled by an equivalent static load and load distribution is taken according to Hertzian law. Tsai-Wu criterion is used to predict the failure of each ply at Gauss points. The failure mode (fibre breakage or matrix cracking) is identified using maximum stress criterion. The material properties at each failed Gauss point is degraded appropriately and the stress analysis is carried out again. This iterative process is repeated until no further damage condition occurs. Numerical examples for both circular and rectangular composite plates are presented. 相似文献
923.
This is the second in a series of two papers generated from a study on probabilistic meshless analysis of cracks. In this
paper, a stochastic meshless method is presented for probabilistic fracture-mechanics analysis of linear-elastic cracked structures.
The method involves an element-free Galerkin method for calculating fracture response characteristics; statistical models
of uncertainties in load, material properties, and crack geometry; and the first-order reliability method for predicting probabilistic
fracture response and reliability of cracked structures. The sensitivity of fracture parameters with respect to crack size,
required for probabilistic analysis, is calculated using a virtual crack extension technique described in the companion paper
[1]. Numerical examples based on mode-I and mixed-mode problems are presented to illustrate the proposed method. The results
show that the predicted probability of fracture initiation based on the proposed formulation of the sensitivity of fracture
parameter is accurate in comparison with the Monte Carlo simulation results. Since all gradients are calculated analytically,
reliability analysis of cracks can be performed efficiently using meshless methods.
Received 20 February 2001 / Accepted 19 December 2001 相似文献
924.
Of the 378 cases of stage 3 carcinoma uterine cervix, only 10 showed vesical invasion, while 19 of 24 cases of stage 4 disease had vesical invasion. Results of this procedure did not alter the management of the disease in any of these cases. From the whole series it was concluded that cysto-urethroscopy is an unnecessary, cost ineffective, invasive procedure which has no role in either diagnosis or in planning the definitive treatment of carcinoma uterine cervix. 相似文献
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927.
McCall J.C. Wipf D.P. Trivedi M.M. Rao B.D. 《Intelligent Transportation Systems, IEEE Transactions on》2007,8(3):431-440
In this paper, we demonstrate a driver intent inference system that is based on lane positional information, vehicle parameters, and driver head motion. We present robust computer vision methods for identifying and tracking freeway lanes and driver head motion. These algorithms are then applied and evaluated on real-world data that are collected in a modular intelligent vehicle test bed. Analysis of the data for lane change intent is performed using a sparse Bayesian learning methodology. Finally, the system as a whole is evaluated using a novel metric and real-world data of vehicle parameters, lane position, and driver head motion. 相似文献
928.
The stability behaviour of columns, subjected to a uniformly distributed axial load and with one end elastically restrained to move axially, is studied in this paper. The elastic axial restraint is represented by means of an axial spring. The finite element formulation, including prebuckling load analysis and stability analysis, is briefly described. Numerical results in terms of stability parameter for various values of axial spring stiffness parameter for four types of boundary conditions are obtained. Stability mode shapes for three specific values of axial spring stiffness parameter are given. 相似文献
929.
Subramani Saravanabhavan Jonnalagadda Raghava Rao Balachandran Unni Nair Thirumalachari Ramasami 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2007,82(11):971-984
BACKGROUND: The leather industry is under pressure to develop environmentally efficient leather‐making processes to comply with modern pollution and discharge legislation. Conventional leather‐processing methods are known to contribute significant pollution loads in tannery wastewaters. The rationalized process described here involves a salt‐free curing, lime and sulfide‐free beamhouse process and post‐tanning followed by tanning employing a reverse leather‐processing technique. RESULTS: Scanning electron microscopy (SEM) analysis substantiated that the grain surface, fibre separation and tight packing of fibres are similar for leathers from conventional and rationalized processes. The functional performance of the leathers is found to be on par with that of conventionally processed leathers. The rationalized leather process reduces the usage and discharge of chemicals by 68% and 82%, respectively. It also enjoys the reduction in biochemical oxygen demand (BOD), chemical oxygen demand, Cl?, SO42? and total solids loads by 58%, 62%, 95%, 66% and 85%, respectively. The rationalized process also results in reduction of water consumption and discharge and energy by 37%, 37% and 38%, respectively. CONCLUSION: The rationalized process utilizes resources efficiently with reduced environmental impact without compromising leather qualities and can be seen as being eco‐efficient compared to the conventional leather process. Copyright © 2007 Society of Chemical Industry 相似文献
930.