为协调港口航道与泊位资源,提高港口船舶调度效率,从单向航道出发,根据先后调度的2艘船舶的进出港方向和所停靠泊位的远近区分两船间的相对关系,建立以总等待时间最少为目标的调度优化数学模型。设计适用于港口船舶调度优化的模拟退火...为协调港口航道与泊位资源,提高港口船舶调度效率,从单向航道出发,根据先后调度的2艘船舶的进出港方向和所停靠泊位的远近区分两船间的相对关系,建立以总等待时间最少为目标的调度优化数学模型。设计适用于港口船舶调度优化的模拟退火多种群遗传算法(Simulated Annealing and Multiple Polulation Genetic Algorithm,SAMPGA),模拟某港口不同调度规模的船舶进行仿真试验,与先到先服务规则(First Come First Served,FCFS)和简单遗传算法(Simple Genetic Algorithm,SGA)进行比较,证明SAMPGA在解决航道和泊位协调调度问题上的适用性。结果表明:在现有的调度规则下对航道和泊位进行协调调度能减少船舶的等待时间和总调度时间,但实际调度规则需要考虑的限制因素更多,需对模型作进一步优化。展开更多
三维片上网络(3D No C)中IP核的测试问题日趋突出,测试规划是提高测试效率的有效方法。基于重用No C作为测试存取机制的并行测试方法,针对IP核测试数据传输带宽与TAM带宽不匹配的问题,提出带分复用方法,对有限带宽的TAM进行动态细分,将...三维片上网络(3D No C)中IP核的测试问题日趋突出,测试规划是提高测试效率的有效方法。基于重用No C作为测试存取机制的并行测试方法,针对IP核测试数据传输带宽与TAM带宽不匹配的问题,提出带分复用方法,对有限带宽的TAM进行动态细分,将多核的测试数据共享同一物理TAM实施并行传输,并结合3D No C结构设计二维编码,建立带宽分配和测试顺序模型,采用多种群遗传模拟退火算法,在总功耗、层功耗双重约束下对IP核的带宽分配和测试顺序进行双重优化,提高并行测试效率以获得最短测试时间。算法中针对测试顺序优化设计移位互换杂交策略,并运用精英配对方法加快种群寻优速度,设计求精操作进一步优化测试时间,通过比较、淘汰、替换机制加强种群间交流,增加种群多样性,避免算法陷入局部最优。以ITC'02标准电路作为测试对象,实验结果表明,该方法通过提高带宽利用率,提升了并行测试效率,降低了资源占用,有效地缩短了测试时间。展开更多
The distribution patterns of mangrove Bruguiera gymnorrhiza population s in southern China are analyzed using the box-counting method of fractal theory. The patterns of B. gymnorrhiza populations could be thought of a...The distribution patterns of mangrove Bruguiera gymnorrhiza population s in southern China are analyzed using the box-counting method of fractal theory. The patterns of B. gymnorrhiza populations could be thought of as fractals as they exhibit self-similarity within the range of scale considered. Their fractal dimensions are not integer but fractional, ranging from 1.04 to 1.51. The unoccupied dimensions change from 0.49 to 0.96. The combined conditions of population density, pattern type and aggregation intensity together influence the values of fractal dimensions of patterns. The box counting is a useful and efficient method to investigate the complexity of patterns. Fractal dimension may be a most desirable and appropriate index for quantifying the horizontal spatial microstructure and fractal behaviors of patterns over a certain range of scales.展开更多
Trawl is a main fishing gear in Chinese fishery,capturing large fish and letting small ones at large.However,long-term use of trawl would result in changes of phenotypic traits of the fish stocks,such as smaller size-...Trawl is a main fishing gear in Chinese fishery,capturing large fish and letting small ones at large.However,long-term use of trawl would result in changes of phenotypic traits of the fish stocks,such as smaller size-at-age and earlier age-at-maturation.In this study,we simulated a fish population with size characteristics of trawl fishing and the population produces one generation of offspring and lives for one year,used trawl to exploit the simulated fish population,and captured individuals by body size.We evaluated the impact of the changes on selectivity parameters,such as selective range and the length at 50% retention.Under fishing pressure,we specified the selectivity parameters,and determined that smaller selection rates and greater length at 50% retention were associated with an increased tendency towards miniaturization.展开更多
The dynamics of a single population with non-overlapping generations can be described deterministically by a scalar difference equation in this study. A discrete-time Beverton- Holt stock recruitment model with Allee ...The dynamics of a single population with non-overlapping generations can be described deterministically by a scalar difference equation in this study. A discrete-time Beverton- Holt stock recruitment model with Allee effect, harvesting and hydra effect is proposed and studied. Model with strong Allee effect results from incorporating mate limitation in the Beverton-Holt model. We show that these simple models exhibit some interesting （and sometimes unexpected） phenomena such as the hydra effect, sudden collapses and essential extinction. Along with this, harvesting is a socio-economie issue to continue any system generation after generation. Different dynamical behaviors for these situations have been illustrated numerically also. The biological implications of our analytical and numerical findings are discussed critically.展开更多
It has been certificated that corridors can help giant pandas to keep their habitat from fragmenting. However there are still losses during the process of moving along corridors. In this study, a mathematical model wi...It has been certificated that corridors can help giant pandas to keep their habitat from fragmenting. However there are still losses during the process of moving along corridors. In this study, a mathematical model with Allee effect is carried out to describe the diffusion of giant pandas between n patches. Some criteria are obtained to keep the system persisting. It is proved that the system has a unique positive w-periodic solution which is globally asymptotically stable. The ecological meanings of these findings are discussed following the results. And some numerical simulations in the Qinling Mountain giant panda nature reservation area are also presented in the end.展开更多
文摘为协调港口航道与泊位资源,提高港口船舶调度效率,从单向航道出发,根据先后调度的2艘船舶的进出港方向和所停靠泊位的远近区分两船间的相对关系,建立以总等待时间最少为目标的调度优化数学模型。设计适用于港口船舶调度优化的模拟退火多种群遗传算法(Simulated Annealing and Multiple Polulation Genetic Algorithm,SAMPGA),模拟某港口不同调度规模的船舶进行仿真试验,与先到先服务规则(First Come First Served,FCFS)和简单遗传算法(Simple Genetic Algorithm,SGA)进行比较,证明SAMPGA在解决航道和泊位协调调度问题上的适用性。结果表明:在现有的调度规则下对航道和泊位进行协调调度能减少船舶的等待时间和总调度时间,但实际调度规则需要考虑的限制因素更多,需对模型作进一步优化。
文摘三维片上网络(3D No C)中IP核的测试问题日趋突出,测试规划是提高测试效率的有效方法。基于重用No C作为测试存取机制的并行测试方法,针对IP核测试数据传输带宽与TAM带宽不匹配的问题,提出带分复用方法,对有限带宽的TAM进行动态细分,将多核的测试数据共享同一物理TAM实施并行传输,并结合3D No C结构设计二维编码,建立带宽分配和测试顺序模型,采用多种群遗传模拟退火算法,在总功耗、层功耗双重约束下对IP核的带宽分配和测试顺序进行双重优化,提高并行测试效率以获得最短测试时间。算法中针对测试顺序优化设计移位互换杂交策略,并运用精英配对方法加快种群寻优速度,设计求精操作进一步优化测试时间,通过比较、淘汰、替换机制加强种群间交流,增加种群多样性,避免算法陷入局部最优。以ITC'02标准电路作为测试对象,实验结果表明,该方法通过提高带宽利用率,提升了并行测试效率,降低了资源占用,有效地缩短了测试时间。
基金The paper is supported by grants from the NSFC (No. 39825106 and 39860023).
文摘The distribution patterns of mangrove Bruguiera gymnorrhiza population s in southern China are analyzed using the box-counting method of fractal theory. The patterns of B. gymnorrhiza populations could be thought of as fractals as they exhibit self-similarity within the range of scale considered. Their fractal dimensions are not integer but fractional, ranging from 1.04 to 1.51. The unoccupied dimensions change from 0.49 to 0.96. The combined conditions of population density, pattern type and aggregation intensity together influence the values of fractal dimensions of patterns. The box counting is a useful and efficient method to investigate the complexity of patterns. Fractal dimension may be a most desirable and appropriate index for quantifying the horizontal spatial microstructure and fractal behaviors of patterns over a certain range of scales.
基金Supported by the Special Fund for Agro-scientific Research in the Public Interest of China(No.201203018)the National Key Technology Research and Development Program of China(No.2006BAD09A05)
文摘Trawl is a main fishing gear in Chinese fishery,capturing large fish and letting small ones at large.However,long-term use of trawl would result in changes of phenotypic traits of the fish stocks,such as smaller size-at-age and earlier age-at-maturation.In this study,we simulated a fish population with size characteristics of trawl fishing and the population produces one generation of offspring and lives for one year,used trawl to exploit the simulated fish population,and captured individuals by body size.We evaluated the impact of the changes on selectivity parameters,such as selective range and the length at 50% retention.Under fishing pressure,we specified the selectivity parameters,and determined that smaller selection rates and greater length at 50% retention were associated with an increased tendency towards miniaturization.
文摘The dynamics of a single population with non-overlapping generations can be described deterministically by a scalar difference equation in this study. A discrete-time Beverton- Holt stock recruitment model with Allee effect, harvesting and hydra effect is proposed and studied. Model with strong Allee effect results from incorporating mate limitation in the Beverton-Holt model. We show that these simple models exhibit some interesting （and sometimes unexpected） phenomena such as the hydra effect, sudden collapses and essential extinction. Along with this, harvesting is a socio-economie issue to continue any system generation after generation. Different dynamical behaviors for these situations have been illustrated numerically also. The biological implications of our analytical and numerical findings are discussed critically.
基金This work is supported by the National Science Foundation of China （No. Z13060）, Beijing Higher Education Young Elite Teacher Project of China （No. YETP1655）, Beijing Talents Fund （No. 2012D005017000003）, Simulation and Evaluation of Indoor Environmental Comfort Improvement （No. 2013BAJ02B0404） and Youth Foundation of Beijing University of Civil Engineering and Architecture （No. Z12082）.
文摘It has been certificated that corridors can help giant pandas to keep their habitat from fragmenting. However there are still losses during the process of moving along corridors. In this study, a mathematical model with Allee effect is carried out to describe the diffusion of giant pandas between n patches. Some criteria are obtained to keep the system persisting. It is proved that the system has a unique positive w-periodic solution which is globally asymptotically stable. The ecological meanings of these findings are discussed following the results. And some numerical simulations in the Qinling Mountain giant panda nature reservation area are also presented in the end.
