Improving multicut in directed trees by upgrading nodes

In this paper, we consider the network improvement problem for multicut by upgrading nodes in a directed tree T = (V, E) with multiple sources and multiple terminals. In a node based upgrading model, a node v can be upgraded at the expense of c(v) and such an upgrade reduces weights on all edges incident to v. The objective is to upgrade a minimum cost subset S ⊆ V of nodes such that the resulting network has a multicut in which no edge has weight larger than a given value D. We first obtain a minimum cardinality node multicut V_c for tree T, then find the minimum cost upgrading set based on the upgrading sets for the subtrees rooted at the nodes in V_c. We show that our algorithm is polynomial when the number of source–terminal pairs is upper bounded by a given value.     

高速列车外形的气动性能数值计算和头部外形的改进

运用流体力学数值计算软件CFX对我国200km／h电动旅客列车的空气动力性能进行了数值模拟计算，针对列车气动外形存在的问题，对列车头部外形进行了改进，并提出了三种列车头部外形改进方案且对其进行了数值模拟研究。计算结果表明，方案三优于其它两种方案，且较改进前列车的空气动力性能有了较大改善。     

极谱法测定地质样品中锡的方法改进

过氧化钠熔融分解样品,热水浸提,试样经铍盐做共沉淀剂,用乙二胺四乙酸(EDTA)消除钙、镁等的影响,在盐酸-氯化铵底液中,用极谱法对锡进行测定,改进并简化了国标方法.对极谱法测定地质样品中锡从熔矿方式、测试温度以及干扰元素的影响及消除等方面进行探讨,并对仪器的工作条件进行优化.锡的方法检出限为10.0μg/g.方法经标准物质验证,测定值与标准值相吻合,并进行不同仪器和方法的对比实验,结果一致,准确度高.方法精密度(RSD,n=12)低于2%.方法效率高、测定结果准确可靠,已应用于大量地质样品的分析中.     

能源节约型技术进步下碳关税对中国经济与环境的影响——基于动态递归可计算一般均衡模型

将动态递归的可计算一般均衡方法应用于碳关税征收影响的研究,建立了测算美国征收碳关税对中国经济与环境影响的动态递归可计算一般均衡模型,并在模型中引入技术进步参数以刻画能源节约型技术进步.模型以2007年作为基年,包含37个生产部门和7个国内国外账户.应用该模型模拟了2020年起美国征收碳关税,在税率从20美元每吨碳排放到80美元每吨碳排放的13种情景下,到2030年期间对我国碳排放和经济发展的不同影响,进而测算在不同的能源节约型技术进步条件下,碳关税对我国经济与环境影响的变动.     

关于城市出租车规划的模型及应用

运用增长率法,建立指数增长的模型,结合规划期的人口规模,预测规划期的居民出行量和居民出行强度,以及乘坐出租车人口,随后利用出租车空载率为主要参数,建立数学模型并预测出租车的最佳数量.利用经济学分析方法,用埃奇沃思盒式图描述交易双方的福利变化,建立均衡时的价格竞争模型,寻求使司机和乘客达到帕累托改进的可能性.分别就油价调整前后的情况,找出调整起租基价和综合单位里程车价能使双方都满意的次优方案.进一步分析了起租基价和里程的合理性,提出了数据采集的建议和方案,并向市公用事业管理部门概括介绍.模型对确定其他类似准公共产品的供应量和定价也具有一定的借鉴意义.     

Numerical aspects of improvement of the unsteady pipe flow equations

The paper presents an analysis of some recently proposed improvements of the water hammer equations, which concern the friction term in the momentum equation. A comparison of the experimental data and numerical results shows that the required damping and smoothing of the pressure wave cannot be obtained by modification of the friction factor only. In order to evaluate the significance of the introduced improvements into the momentum equation, the accuracy of the numerical solution has been analysed using the modified equation approach. The analysis shows why the physical dissipation process observed in the water hammer phenomenon cannot be reproduced with the commonly used source term in Darcy–Weisbach form, representing friction force in the momentum equation. Therefore, regardless of the proposed form of the friction factor for unsteady flow, the model of water hammer improved in such a way keeps its hyperbolic character. Consequently, it cannot ensure the expected effects of damping and smoothing of the calculation head oscillations. Copyright © 2007 John Wiley & Sons, Ltd.     

Optimization of multiweighing packing proceedings

In this paper we study the variability reduction gain that results from the use of multiweighing proceedings in packing processes with the objective of sales at constant nominal weights. According to this, we have proposed a packing algorithm that includes the formation of units with variable number of pieces and we have obtained the value of the percentage variability reduction index. Collaborator in the Catalan Institute of Tecnology (ICT).     

1．5GHz锯材超导腔的研制

介绍铌材超导腔的研制进展，重点讨论了国产铌腔的材料改性，以及相应的超导腔性能的改进．叙述了１．５ＧＨｚ铌腔的腔形设计，分析了铌材的射频性能和机械性能，制定了铌腔制作与后处理的特定工艺．最后给出了１．５ＧＨｚ铌材超导腔的低温实验结果．     

Improvement of lysine production by analog-sensitive and auxotroph mutants of the acetylene-utilizing bacterium gordona bronchialis (Rhodococcus bronchialis)

An acetylene utilizingGordona (Rhodococcus) bronchialis strain, screened for the production of fine chemicals, was found to be capable of producing small amounts of lysine. Attempts to produce amino-acid analogresistant and/or sensitive mutants and auxotrophs of this strain with increased lysine production were made following UV-irradiation orN-methyl-N’-nitro-N-nitrosoguanidine (MNNG) treatment. The bacterium exhibited surprisingly high resistance levels to the aforementioned mutagens which is attributed to highly effective inborn-repair systems. Natural resistance to high levels ofS-(2-aminoethyl)-l-cysteine (AEC) (2%) was observed, in contrast withd, l-aspartic acid hydroxamate (AAH),l-lysine hydroxamate (LHX) and β-fluoropyruvate (FP). A variety of amino-acid analog-resistant (AAH^r, LHX^r) or analog-sensitive (FP^s) mutants were produced following UV-irradiation or MNNG treatment. Similarly, a large number of auxotrophs (68) of different types were also obtained. From these, one FP^s mono-auxotroph and two poly-auxotrophs (with at least one requirement for the aspartic acid family) showed an increased lysine production (~1.8 g/L) comparable (4 g/L) to that found in other bacteria capable of utilizing long-chain hydrocarbons(1).     

Further improvement of weakly nonlinear theory of hydrodynamic stability

The problems of the weakly nonlinear theory of hydrodynamic stability has been re-addressed; namely, (i) why is the radius of convergence of its solution too small? (ii) it is not appropriate to use it to deal with the evolution problem of disturbances; the main reason is that the way of calculating the mean flow distortion is inappropriate, (iii) it cannot be used to deal with the initial value problem. Ways of its improvement were proposed. Its correctness was confirmed by its comparison with the results of numerical simulations.