The Experts below are selected from a list of 42 Experts worldwide ranked by ideXlab platform
S.n. Bhatt - One of the best experts on this subject based on the ideXlab platform.
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Experiences with parallel N-body simulation
IEEE Transactions on Parallel and Distributed Systems, 2000Co-Authors: S.n. BhattAbstract:This paper describes our experiences developing high-performance code for astrophysical N-body simulations. Recent N-body methods are based on an adaptive tree structure. The tree must be built and maintained across physically distributed memory; moreover, the communication requirements are irregular and adaptive. Together with the need to balance the computational work-load among processors, these issues pose interesting challenges and tradeoffs for high-performance implementation. Our implementation was guided by the need to keep solutions simple and general. We use a technique for implicitly representing a dynamic global tree across multiple processors which substantially reduces the programming complexity as well as the performance overheads of distributed memory architectures. The contributions include methods to vectorize the computation and minimize communication time which are theoretically and experimentally justified. The code has been tested by varying the number and distribution of bodies on different configurations of the Connection Machine CM-5. The overall performance on instances with 10 million bodies is typically over 48 percent of the peak Machine Rate, which compares favorably with other approaches.
T. Eric Mcconnell - One of the best experts on this subject based on the ideXlab platform.
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Unit Costs and Trends within Louisiana's Logging Contract Rate
Forest Products Journal, 2020Co-Authors: T. Eric McconnellAbstract:Abstract Quarterly unit costs for a hypothetical logging firm were determined from the logging contract Rate for Louisiana spanning the years 1992 to 2018. Machine Rate methods were employed to dis...
Kris Verheyen - One of the best experts on this subject based on the ideXlab platform.
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Logging operations in pine stands in Belgium with additional harvest of woody biomass: yield, economics, and energy balance
Canadian Journal of Forest Research, 2015Co-Authors: Pieter Vangansbeke, Jeroen Osselaere, Miet Van Dael, P. De Frenne, Robert Gruwez, Leen Gorissen, Luc Pelkmans, Kris VerheyenAbstract:Due to the enhanced demands for woody biomass, it is increasingly relevant to assess possibilities to harvest forest residues in addition to logs. Here, eight stRategies for whole-tree harvesting from clearcuts and early thinnings of pine (Pinus nigra Arnold) stands in northern Belgium are evaluated. A detailed cost analysis using the Machine-Rate method was conducted along with scenario and sensitivity analyses of the variables affecting the harvesting cost. On average, we found much higher revenue for logs than for wood chips from forest residues. In clearcuts, a mobile chipper was more profitable than a roadside chipper. On the other hand, the harvesting cost of logs was higher for early thinnings than for clearcuts. However, the revenue remained higher than for chips, making the sepaRate harvesting of logs and chips more cost effective than chipping whole trees. In the latter case, an excavator, a forwarder, and a roadside chipper were more cost effective than a harvester, a tractor with trailer, and ...
William Elliot - One of the best experts on this subject based on the ideXlab platform.
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Productivity and cost of integRated harvesting for fuel reduction thinning in mixed-conifer forest
Forest Products Journal, 2011Co-Authors: Brian Vitorelo, Han-sup Han, William ElliotAbstract:Removing submerchantable size trees and forest residues as well as sawlogs is preferred in fuel reduction thinning because it improves treatment effectiveness and avoids slash burning. Fuel reduction thinning was investigated to describe integRated harvesting Machine processes and productivity and to characterize stump-to-truck costs for sawlogs and biomass for energy production. This system was studied in mixed-conifer forest on land owned by the US Forest Service in northern California and southern Oregon. Detailed time-study methods were paired with standard Machine Rate calculation methods to evaluate productivity and costs for the system. Sensitivity analysis and a standardized comparison were performed to evaluate costs and productivity under varying operation parameters. Treatment costs (stump-to-truck; without mobilization, overhead, or profit) were US$0.42/ft 3 for sawlogs and US$52.41 per bone dry ton (BDT) for biomass. Standardized unit production costs for sawlog skidding varied little, but the smaller skidder was clearly preferable for biomass tree skidding when external skidding distances exceeded 200 feet. The grinder had the highest hourly cost of any Machine in the system and its unit production cost (US$/BDT) was sensitive to changes in utilization Rate. Evaluations on system balance showed that improved utilization of the grinder could be accomplished as the grinder and loader often waited for a chip van. IntegRated harvesting was a cost-effective way of implementing fuel reduction thinning method because of the potential for sawlog revenues to offset some of the biomass extraction cost. © 2011 Forest Products Society.
Pieter Vangansbeke - One of the best experts on this subject based on the ideXlab platform.
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Logging operations in pine stands in Belgium with additional harvest of woody biomass: yield, economics, and energy balance
Canadian Journal of Forest Research, 2015Co-Authors: Pieter Vangansbeke, Jeroen Osselaere, Miet Van Dael, P. De Frenne, Robert Gruwez, Leen Gorissen, Luc Pelkmans, Kris VerheyenAbstract:Due to the enhanced demands for woody biomass, it is increasingly relevant to assess possibilities to harvest forest residues in addition to logs. Here, eight stRategies for whole-tree harvesting from clearcuts and early thinnings of pine (Pinus nigra Arnold) stands in northern Belgium are evaluated. A detailed cost analysis using the Machine-Rate method was conducted along with scenario and sensitivity analyses of the variables affecting the harvesting cost. On average, we found much higher revenue for logs than for wood chips from forest residues. In clearcuts, a mobile chipper was more profitable than a roadside chipper. On the other hand, the harvesting cost of logs was higher for early thinnings than for clearcuts. However, the revenue remained higher than for chips, making the sepaRate harvesting of logs and chips more cost effective than chipping whole trees. In the latter case, an excavator, a forwarder, and a roadside chipper were more cost effective than a harvester, a tractor with trailer, and ...
