Opportunistic networks are random networks and do not communicate with each other among respective communication areas.This situation leads to great difficulty in message transfer.This paper proposes a reducing energy...Opportunistic networks are random networks and do not communicate with each other among respective communication areas.This situation leads to great difficulty in message transfer.This paper proposes a reducing energy consumption optimal selection of path transmission(OSPT) routing algorithm in opportunistic networks.This algorithm designs a dynamic random network topology,creates a dynamic link,and realizes an optimized selected path.This algorithm solves a problem that nodes are unable to deliver messages for a long time in opportunistic networks.According to the simulation experiment,OSPT improves deliver ratio,and reduces energy consumption,cache time and transmission delay compared with the Epidemic Algorithm and Spray and Wait Algorithm in opportunistic networks.展开更多
A layered algorithm by bidirectional searching is proposed in this paper to solve the problem that it is difficult and time consuming to reach an optimal solution of the route search with multiple parameter restrictio...A layered algorithm by bidirectional searching is proposed in this paper to solve the problem that it is difficult and time consuming to reach an optimal solution of the route search with multiple parameter restrictions for good quality of service. Firstly, a set of reachable paths to each intermediate node from the source node and the sink node based on adjacent matrix transformation are calculated respectively. Then a temporal optimal path is selected by adopting the proposed heuristic method according to a non-linear cost function. When the total number of the accumulated nodes by bidirectional searching reaches n-2, the paths from two directions to an intermediate node should be combined and several paths via different nodes from the source node to the sink node can be obtained, then an optimal path in the whole set of paths can be taken as the output route. Some simulation examples are included to show the effectiveness and efficiency of the proposed method. In addition, the proposed algorithm can be implemented with parallel computation and thus, the new algorithm has better performance in time complexity than other algorithms. Mathematical analysis indicates that the maximum complexity in time, based on parallel computation, is the same as the polynomial complexity of O(kn2-3kn+k), and some simulation results are shown to support this analysis.展开更多
The methodology of 5-axis cutter selection to avert collision for free-form surface machining by flat-end cutters is presented. The combination of different cutters is adopt aiming at short machining time and high pre...The methodology of 5-axis cutter selection to avert collision for free-form surface machining by flat-end cutters is presented. The combination of different cutters is adopt aiming at short machining time and high precision. The optimal small cutter is determined based on the geometric information of the points where a cutter most probably collide with the machined surface. Several larger cutters are selected to machine the surface in order to find the interference-free area. The difference of machining time for this area between the optimal small cutter and the large cutters is calculated. The functional relationship between the machining time and the radius of a cutter is established, by which the optimal number of cutters is obtained. The combination of cutters, which possesses the minimum overall machining time, is selected as the optimal cutter sizes. A case study has demonstrated the validity of the proposed methodology and algorithms.展开更多
From the view of system theory, modern agriculture in a region embodies elements conformity, structure optimization, multi-functionality and sustainable development. This paper first expounds on the relationship among...From the view of system theory, modern agriculture in a region embodies elements conformity, structure optimization, multi-functionality and sustainable development. This paper first expounds on the relationship among agricultural elements, structure, function and development theoretically, compartmentalizes agriculture types based on human-land elements matching, and depicts the development path of agricultural multi-functionality. it shows that the matching of human-land elements is a key to agricultural types, and the multi-functionality is an indication of agricultural development stages. At last, as a case study of Suzhou in eastern coastal area, the paper analyzes the evolvement situation and developing mechanism and some typical models of modern agriculture which suit to agriculture system evolvement. The results .show that in Suzhou the agriculture productivity, has improved greatly; And along with the agriculture structure optimizing, agriculture function has translated from ＂production ＂ to ＂non- production and production ＂. With simulation of agricultural trend in Suzhou, it is .found that Suzhou has a LP- dependence （labor productivity） on agricultural element, so Suzhou will has much more potential in land productivity. Based on the above analysis on agricultural system, some typical patterns on modern agriculture in Suzhou are brought up, such as export-oriented agriculture, enterprises-leading agriculture, science and technology, parks agriculture, stereoseopic agriculture, and tourism and sightseeing agriculture.展开更多
基金Supported by the National Natural Science Foundation of China(No.61379057,61073186,61309001,61379110,61103202)Doctoral Fund of Ministry of Education of China(No.20120162130008)the National Basic Research Program of China(973 Program)(No.2014CB046305)
文摘Opportunistic networks are random networks and do not communicate with each other among respective communication areas.This situation leads to great difficulty in message transfer.This paper proposes a reducing energy consumption optimal selection of path transmission(OSPT) routing algorithm in opportunistic networks.This algorithm designs a dynamic random network topology,creates a dynamic link,and realizes an optimized selected path.This algorithm solves a problem that nodes are unable to deliver messages for a long time in opportunistic networks.According to the simulation experiment,OSPT improves deliver ratio,and reduces energy consumption,cache time and transmission delay compared with the Epidemic Algorithm and Spray and Wait Algorithm in opportunistic networks.
文摘A layered algorithm by bidirectional searching is proposed in this paper to solve the problem that it is difficult and time consuming to reach an optimal solution of the route search with multiple parameter restrictions for good quality of service. Firstly, a set of reachable paths to each intermediate node from the source node and the sink node based on adjacent matrix transformation are calculated respectively. Then a temporal optimal path is selected by adopting the proposed heuristic method according to a non-linear cost function. When the total number of the accumulated nodes by bidirectional searching reaches n-2, the paths from two directions to an intermediate node should be combined and several paths via different nodes from the source node to the sink node can be obtained, then an optimal path in the whole set of paths can be taken as the output route. Some simulation examples are included to show the effectiveness and efficiency of the proposed method. In addition, the proposed algorithm can be implemented with parallel computation and thus, the new algorithm has better performance in time complexity than other algorithms. Mathematical analysis indicates that the maximum complexity in time, based on parallel computation, is the same as the polynomial complexity of O(kn2-3kn+k), and some simulation results are shown to support this analysis.
基金Funded by the Doctorate Degree Program Foundation of the Ministry of Education (No. 2000061120)
文摘The methodology of 5-axis cutter selection to avert collision for free-form surface machining by flat-end cutters is presented. The combination of different cutters is adopt aiming at short machining time and high precision. The optimal small cutter is determined based on the geometric information of the points where a cutter most probably collide with the machined surface. Several larger cutters are selected to machine the surface in order to find the interference-free area. The difference of machining time for this area between the optimal small cutter and the large cutters is calculated. The functional relationship between the machining time and the radius of a cutter is established, by which the optimal number of cutters is obtained. The combination of cutters, which possesses the minimum overall machining time, is selected as the optimal cutter sizes. A case study has demonstrated the validity of the proposed methodology and algorithms.
基金supported by Major Program of the National Natural Science Foundation of China (Grant No.40771014)
文摘From the view of system theory, modern agriculture in a region embodies elements conformity, structure optimization, multi-functionality and sustainable development. This paper first expounds on the relationship among agricultural elements, structure, function and development theoretically, compartmentalizes agriculture types based on human-land elements matching, and depicts the development path of agricultural multi-functionality. it shows that the matching of human-land elements is a key to agricultural types, and the multi-functionality is an indication of agricultural development stages. At last, as a case study of Suzhou in eastern coastal area, the paper analyzes the evolvement situation and developing mechanism and some typical models of modern agriculture which suit to agriculture system evolvement. The results .show that in Suzhou the agriculture productivity, has improved greatly; And along with the agriculture structure optimizing, agriculture function has translated from ＂production ＂ to ＂non- production and production ＂. With simulation of agricultural trend in Suzhou, it is .found that Suzhou has a LP- dependence （labor productivity） on agricultural element, so Suzhou will has much more potential in land productivity. Based on the above analysis on agricultural system, some typical patterns on modern agriculture in Suzhou are brought up, such as export-oriented agriculture, enterprises-leading agriculture, science and technology, parks agriculture, stereoseopic agriculture, and tourism and sightseeing agriculture.
