The geometry relation and the contact point-pairs detection between two three dimensional(3D) objects with arbitrary shapes are essential problems involved in discontinuous computation and computational geometry. This...The geometry relation and the contact point-pairs detection between two three dimensional(3D) objects with arbitrary shapes are essential problems involved in discontinuous computation and computational geometry. This paper reported a geometry relation judgment and contact searching algorithm based on Contact Theory. A contact cover search algorithm is proposed to find all the possible contact cover between two blocks. Two blocks can come to contact only on these covers. Each contact cover can define a possible contact point-pair between two blocks. Data structure and flow chart are provided, as well as some examples in details.Contact problems involving concave blocks or parallel planes are considered to be very difficult in past and are solved by this algorithm. The proposed algorithm is compacted and applicable to the discontinuous computation, such as robotic control, rock mass stability, dam stability etc. A 3D cutting and block searching algorithm is also proposed in this study and used to search the outer boundary of the 3D entrance block when 3D concave blocks are encountered. The 3D cutting and block searching algorithm can be also used to form the block system for jointed rock.展开更多
Energy consumption of block-cutting machines represents a major cost item in the processing of travertines and other natural stones. Therefore, determining the optimum sawing conditions for a particular stone is of ma...Energy consumption of block-cutting machines represents a major cost item in the processing of travertines and other natural stones. Therefore, determining the optimum sawing conditions for a particular stone is of major importance in the natural stone-processing industry. An experimental study was carried out utilizing a fully instrumented block-cutter to investigate the sawing performances of five different types of travertine blocks during cutting with a circular diamond saw. The sawing tests were performed in the down-cutting mode. Performance measurements were determined by measuring the cutting speed and energy consumption. Then, specific energy was determined. The one main cutting parameter, cutting speed, was varied in the investigation of optimum cutting performance. Furthermore, some physico-mechanical properties of file travertine blocks were determined in the laboratory. As a result, it is found that the energy consumption （specific energy） of block cutting machines is highly affected by cutting speed. It is determined that specific energy value usually decreases when cutting speed increases. When the cutting speed is higher than the determined value, the diamond saw can become stuck in the travertine block; this situation can be a problem for the block-cutting machine. As a result, the optimum cutting speed obtained for the travertine mines examined is approximately 1.5-2.0 m/min.展开更多
针对目前多规格矩形件优化下料算法在生成单板材布局时通常仅将材料利用率作为主优化目标,且在路径优化方面未能充分挖掘共边切割潜力,提出两方面的改进。一方面,提出等高块共边切割策略,并在生成布局图的过程中设置条带优先级,尽可能...针对目前多规格矩形件优化下料算法在生成单板材布局时通常仅将材料利用率作为主优化目标,且在路径优化方面未能充分挖掘共边切割潜力,提出两方面的改进。一方面,提出等高块共边切割策略,并在生成布局图的过程中设置条带优先级,尽可能多地生成等高块。另一方面,在顺序价值校正(Sequential Value Correction,SVC)框架和以生产成本(材料成本和切割成本之和)最小为下料方案优化目标的基础上,提出在生成单板材布局时以综合价值(矩形件总价值与切割成本之差)最大作为优化目标,通过求解有界背包问题,构建同时考虑切割成本的布局图生成算法。实验结果表明,所提算法和切割策略在提高材料利用率、降低切割成本方面具有可行性和有效性。展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 51479001, 41471052)the China Institute of Water Resources and Hydropower Research Research & Development Support Program(Grant Nos. GE0145B462017, GE0145B692017)
文摘The geometry relation and the contact point-pairs detection between two three dimensional(3D) objects with arbitrary shapes are essential problems involved in discontinuous computation and computational geometry. This paper reported a geometry relation judgment and contact searching algorithm based on Contact Theory. A contact cover search algorithm is proposed to find all the possible contact cover between two blocks. Two blocks can come to contact only on these covers. Each contact cover can define a possible contact point-pair between two blocks. Data structure and flow chart are provided, as well as some examples in details.Contact problems involving concave blocks or parallel planes are considered to be very difficult in past and are solved by this algorithm. The proposed algorithm is compacted and applicable to the discontinuous computation, such as robotic control, rock mass stability, dam stability etc. A 3D cutting and block searching algorithm is also proposed in this study and used to search the outer boundary of the 3D entrance block when 3D concave blocks are encountered. The 3D cutting and block searching algorithm can be also used to form the block system for jointed rock.
文摘Energy consumption of block-cutting machines represents a major cost item in the processing of travertines and other natural stones. Therefore, determining the optimum sawing conditions for a particular stone is of major importance in the natural stone-processing industry. An experimental study was carried out utilizing a fully instrumented block-cutter to investigate the sawing performances of five different types of travertine blocks during cutting with a circular diamond saw. The sawing tests were performed in the down-cutting mode. Performance measurements were determined by measuring the cutting speed and energy consumption. Then, specific energy was determined. The one main cutting parameter, cutting speed, was varied in the investigation of optimum cutting performance. Furthermore, some physico-mechanical properties of file travertine blocks were determined in the laboratory. As a result, it is found that the energy consumption （specific energy） of block cutting machines is highly affected by cutting speed. It is determined that specific energy value usually decreases when cutting speed increases. When the cutting speed is higher than the determined value, the diamond saw can become stuck in the travertine block; this situation can be a problem for the block-cutting machine. As a result, the optimum cutting speed obtained for the travertine mines examined is approximately 1.5-2.0 m/min.
文摘针对目前多规格矩形件优化下料算法在生成单板材布局时通常仅将材料利用率作为主优化目标,且在路径优化方面未能充分挖掘共边切割潜力,提出两方面的改进。一方面,提出等高块共边切割策略,并在生成布局图的过程中设置条带优先级,尽可能多地生成等高块。另一方面,在顺序价值校正(Sequential Value Correction,SVC)框架和以生产成本(材料成本和切割成本之和)最小为下料方案优化目标的基础上,提出在生成单板材布局时以综合价值(矩形件总价值与切割成本之差)最大作为优化目标,通过求解有界背包问题,构建同时考虑切割成本的布局图生成算法。实验结果表明,所提算法和切割策略在提高材料利用率、降低切割成本方面具有可行性和有效性。
