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991.
There are two types of organisms’ grouping in nature: mono-species populations and multi-species communities. Here at during the process of evolution the adaptability of a trait is to be tested both at population and ecocenotic levels. Size of a genome is one of the major adaptive traits, which widely varies in eukaryotic species. By contrast, prokaryotes with their small genomes are considered to have genome reduction evolutionary trend. Domination of this trend is mostly founded on population-level models. In this paper we in silico study interactions of ecocenotic and population levels. The trend of genome and metabolism reduction in prokaryotic communities was shown to be major only in comfortable environmental conditions. In subcomfortable conditions, genome and metabolism reduction leads to community simplification (in extreme case to community death). Pessimum conditions promote metabolism integration of a community and induce reciprocal genes acquiring.  相似文献   
992.
改进的LMS算法在Simulink仿真平台实现   总被引:1,自引:0,他引:1  
目的将改进的变步长LMS算法在Simulink平台上实现。方法对LMS算法进行基础研究,详细地探究变步长算法在信号处理中的收敛速度和失调两个方面的内容,改进变步长算法,并验证算法的有效性。基于S-fuction,对改进的LMS算法建模,通过算法模块调用改进算法程序,达到对信号滤波的目的。结果仿真结果表明,算法模块能够实现算法滤波功能,能有效地抵消干扰。结论算法应用于Simulink建模,算法模块能够适应不同的Simulink平台,提高了对算法的开发与应用的效率。  相似文献   
993.
In this, Part I of a two-part series, a review is presented of some generally appreciated residence time properties of multimedia models. The novel concept of “distant residence time” (DRT) is developed to provide additional insights into the characterization of environmental transport. DRT is the proportionality constant between the rate of emission of a contaminant into one compartment or region and the mass that results at steady-state in a distant compartment. The concept, which can be viewed as an expression of environmental mobility, is illustrated for various configurations of compartments and is shown to be consistent with the concepts of global fractionation and cold condensation. The dynamic responses of chemical quantities at distant locations to changing emission rates are also discussed. It is shown that approximate solutions for DRTs and their time dependence are useful for characterizing the long-range transport of chemicals and for interpreting monitoring data.  相似文献   
994.
    
A method for calculating the source terms including values of leak rate, phase fraction, final velocity, and temperature at the position where the leakage jet has expanded to atmospheric pressure from a CO2 pipeline containing impurities (methane and water) is presented with regard to the time‐dependency of the source terms during the leakage. The thermodynamical properties for the mixture are calculated using the Soave‐Redlich‐Kwong equation of state with modified 1st order Huron‐Vidal mixing rule, which is adjustable in PVTsim. The results for the solubility of water in CO2 have shown that this thermodynamic model provides accurate predictions for the mixture properties. The thermodynamic model has been used along with a robust transient two‐phase flow simulator, OLGA, to simulate the leak from the pipeline. Finally, the predicted time‐dependant source terms (Release Rate, Phase Fraction, Final Velocity, and Temperature in the downstream of the leak) were used as input into the dispersion model (UDM) in form of sequential segments.  相似文献   
995.
    
Industrial trials of membrane separation of CO2 from flue gas generated by a lignite‐fired power station are reported. A hollow fiber Air Products PRISM and a spiral wound Dow Filmtec® NF3838/30FF membrane were separately trialed. The CO2 permeance and selectivity through the PRISM membrane fell significantly in the initial hours of operation, reflecting competitive sorption effects and concentration polarisation. Alternatively, the wet flue gas enabled a facilitated transport mechanism to operate for the NF3838/30FF membrane and the CO2 permeance and selectivity increased significantly compared to the dry membrane. Standard correlations were able to simulate the pressure drops through the modules.© 2015 Society of Chemical Industry and John Wiley & Sons, Ltd  相似文献   
996.
    
The hazardous chemicals maritime transportation system (HCMTS) belongs to a typical complex tech-social system, which is comprised of multiple functions with interactions. To quantitatively assess the risks triggered by failure coupling links (CLs) between upstream and downstream functions, a hybrid method integrating the Functional Resonance Analysis Method (FRAM), fuzzy set theory, and risk matrix is proposed in the present study. A total of 10 essential functions and 16 CLs involved in HCMTS were identified by FRAM. The fuzzy set theory was adopted to aggregate the weights of risk consequence and likelihood for CLs. A risk matrix with a continuous scale was utilized to assess and rank the CLs’ risks. The results have been demonstrated by the comparisons, indicated that the risk indexes (RIs) of the CLs between the functions < Consignment of HCs> and <Undertaking the transportation>, <Consignment of HCs> and <Declaration of HCs>, <Loading HCs in port> and <Ship navigation at sea > are higher in the whole chain of HCMTS.  相似文献   
997.
998.
综合运用多种模型对企业货运事故预测进行了讨论,并根据一组实际数据对模型运用及检验进行了分析。  相似文献   
999.
    
Introduction: The European Union (EU) has developed different strategies to internalize the costs of excessive motor traffic in the road freight transport sector. One of these is a relaxation of restrictions on the size and load capacity of trucks that circulate between member States and a proposal has been made for Longer and Heavier Vehicles (LHVs) to be allowed to circulate across borders. LHVs are the so-called “megatrucks” (i.e., trucks with a length of 25 meters and a weight of 60 tonnes). Megatrucks have allowed to circulate for decades in some European countries such as Norway, Finland, and Sweden, world leaders in traffic accident prevention, although the impact that cross-border traffic would have on road safety is still unknown. Methods: This article provides an econometric analysis of the potential impact on road safety of allowing the circulation of “megatrucks” throughout the EU. Results: The findings show that countries that currently allow megatrucks to circulate present lower traffic accident and fatality levels, on average. Conclusions: The circulation of this type of vehicle is only advisable in countries where there is a certain degree of maturity and demonstrated achievements in the field of road safety. Practical applications: European countries that have allowed megatruck circulation obtaining better road safety outcomes in terms of accidents, although the accident lethality rate seems to be higher. Consequently, introducing megatruck circulation requires a prior proper preparation and examination.  相似文献   
1000.
危险化学品在运输过程中的危险分析及控制   总被引:2,自引:1,他引:2  
分析了危险化学品在运输中发生火灾爆炸的致灾因子及其危害的特点,并采用定量计算的方法给出危害的直观描述,进而提出危险化学品在运输过程中的控制措施.  相似文献   
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