Browsing by Subject "Preconditioning"
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Item Evaluation of High-intensity and Low-intensity Preconditioning Systems(2012-02-14) Orsak, Andrew NathanSteer calves n = 345 (year 1 n = 183; 253 ? 35 kg, year 2 n = 162; 241 ? 36 kg initial BW) were used to evaluate 56-d preconditioning systems in each of two years. Angus- and Charolais-sired calves out of crossbred dams were assigned to systems within breed and BW strata. The systems consisted of ad libitum access to a self-fed milo-based diet in drylot (DL); ad libitum access to the same self-fed diet while grazing dormant warm season pasture (SF); and hand-fed 20 precent CP pellets (2.1 kg 3 times/wk; equivalent to 0.89 kg/steer per d) while grazing dormant warm season pasture (HF). Steers were weighed after overnight shrink on d 0, 28, and 56. The economic analysis was based on current local prices for cattle and inputs. Morbidity and mortality rates were similar among treatments. In year 1, one steer was removed from SF (mechanical) and one from DL (chronic bloat). In year 2, two steers were treated for respiratory disease (DL and HF) and mortalities occurred in DL (1 steer, digestive), HF (1 steer, unknown) and SF (1 steer, mechanical). Shrink from weaning to d 0 averaged 4.45 percent across years and was similar (P = 0.70) among treatments. Across years, ADG was lower in HF vs. SF or DL-fed steers (P < 0.01), which had similar rates of gain (P = 0.29; 0.13, 0.98, and 0.96 ? 0.03 kg/d yr 1; P = 0.13; 0.14, 0.73, 0.79 ? 0.06 kg/d for HF, SF, and DL, respectively). In year 1, daily feed intake was similar (9.03 vs. 10.0 ? 0.96 kg/steer; P = 0.17) among SF and, DL systems. In year 2, intake was greater for DL than SF (10.1 vs. 8.3 ? 0.25; P < 0.01). Feed efficiency (G:F) was greater for HF steers vs. SF or DL steers in year 1 (P < 0.01). (P=0.91; 0.04, 0.11, 0.09, ? 0.04 for year 1 HF, SF, and DL respectively). In year 2, G:F did not differ among treatments (P= 0.50; 0.16, 0.09, 0.08 HF, SF, DL respectively). Forage utilization was not quantified; these values represent gain per unit of purchased feed delivered, a metric favoring groups fed at lower rates. Preconditioning costs were 73.50, 175.12 and 167.20 $/steer (year 1) and 53.58, 152.72, and 141.68 $/steer (year 2; HF, SF, and DL respectively). These systems resulted in losses of -57.89, -67.59, and -58.80 $/steer (SE = 4.99; P= 0.38) in year 1, and -28.35,-80.00, and -64.55 $/steer (SE = 17.39; P = 0.18) in year 2 for HF, SF, and DL. Price premiums of 10.61, 10.51, and 9.18 $/45.4 kg (SE = 0.85; P=0.46) in year 1 and 5.79, 14.01, and 11.31 $/45.4 kg (SE = 3.25; P=0.27) in year 2 would be required for HF, SF, and DL to be par with sale at weaning. Overall preconditioning was unprofitable for both years and would require substantial price premiums. Although a lower intensity pasture system reduced overall input cost, it did not result in profitability. Providing ad libitum access to a diet while on pasture did not result in any advantages over drylot based systems.Item Parallel algorithms for inductance extraction(Texas A&M University, 2007-09-17) Mahawar, HemantIn VLSI circuits, signal delays play an important role in design, timing verification and signal integrity checks. These delays are attributed to the presence of parasitic resistance, capacitance and inductance. With increasing clock speed and reducing feature sizes, these delays will be dominated by parasitic inductance. In the next generation VLSI circuits, with more than millions of components and interconnect segments, fast and accurate inductance estimation becomes a crucial step. A generalized approach for inductance extraction requires the solution of a large, dense, complex linear system that models mutual inductive effects among circuit elements. Iterative methods are used to solve the system without explicit computation of the system matrix itself. Fast hierarchical techniques are used to compute approximate matrix-vector products with the dense system matrix in a matrix-free way. Due to unavailability of system matrix, constructing a preconditioner to accelerate the convergence of the iterative method becomes a challenging task. This work presents a class of parallel algorithms for fast and accurate inductance extraction of VLSI circuits. We use the solenoidal basis approach that converts the linear system into a reduced system. The reduced system of equations is solved by a preconditioned iterative solver that uses fast hierarchical methods to compute products with the dense coefficient matrix. A Green????????????s function based preconditioner is proposed that achieves near-optimal convergence rates in several cases. By formulating the preconditioner as a dense matrix similar to the coefficient matrix, we are able to use fast hierarchical methods for the preconditioning step as well. Experiments on a number of benchmark problems highlight the efficient preconditioning scheme and its advantages over FastHenry. To further reduce the solution time of the software, we have developed a parallel implementation. The parallel software package is capable of analyzing interconnects con- figurations involving several conductors within reasonable time. A two-tier parallelization scheme enables mixed mode parallelization, which uses both OpenMP and MPI directives. The parallel performance of the software is demonstrated through experiments on the IBM p690 and AMD Linux clusters. These experiments highlight the portability and efficiency of the software on multiprocessors with shared, distributed, and distributed-shared memory architectures.Item Support graph preconditioning for elliptic finite element problems(2009-05-15) Wang, MeiqiuA relatively new preconditioning technique called support graph preconditioning has many merits over the traditional incomplete factorization based methods. A major limitation of this technique is that it is applicable to symmetric diagonally dominant matrices only. This work presents a technique that can be used to transform the symmetric positive definite matrices arising from elliptic finite element problems into symmetric diagonally dominant M-matrices. The basic idea is to approximate the element gradient matrix by taking the gradients along chosen edges, whose unit vectors form a new coordinate system. For Lagrangian elements, the rows of the element gradient matrix in this new coordinate system are scaled edge vectors, thus a diagonally dominant symmetric semidefinite M-matrix can be generated to approximate the element stiffness matrix. Depending on the element type, one or more such coordinate systems are required to obtain a global nonsingular M-matrix. Since such approximation takes place at the element level, the degradation in the quality of the preconditioner is only a small constant factor independent of the size of the problem. This technique of element coordinate transformations applies to a variety of first order Lagrangian elements. Combination of this technique and other techniques enables us to construct an M-matrix preconditioner for a wide range of second order elliptic problems even with higher order elements. Another contribution of this work is the proposal of a new variant of Vaidya?s support graph preconditioning technique called modified domain partitioned support graph preconditioners. Numerical experiments are conducted for various second order elliptic finite element problems, along with performance comparison to the incomplete factorization based preconditioners. Results show that these support graph preconditioners are superior when solving ill-conditioned problems. In addition, the domain partition feature provides inherent parallelism, and initial experiments show a good potential of parallelization and scalability of these preconditioners.Item Will super juniper-eating sires produce super juniper-eating offspring?(2011-03-03) Tidwell, Kendall W.; Tidwell, Kendall; Scott, Cody B.; Simpson, Warren K.; Walker, John W.; Salisbury, Micheal W.; Angelo State University. Department of Agriculture.When preconditioned in pens, goats develop a preference for juniper on pasture. The objective of this study was to see if sires selectively bred for high juniper consumption produce offspring that consume more juniper than offspring from sires chosen for production characteristics. Five sires chosen for high juniper consumption and five sires chosen for production characteristics were bred to 7 does each (n= 70). Kids were weaned at 90 days of age and placed in individual pens for feeding trials. Consumption of juniper was measured and compared among sire groups. Body condition scores and weights were taken and compared among sire groups after goats were on feed for 30 days following each feeding trial. There were no differences in juniper consumption, body condition scores, and weights among treatments. Goats increased juniper consumption daily in individual pens.