Simulation of Economic Dynamics under Ecological Balance Conditions

A model of economic dynamics under stable ecological balance conditions is proposed. A methodology of construction of an optimal growth path is constructed for this model.     

多级复合布尔函数性能研究

本文研究了加法复合布尔函数和乘法复合布尔函数,在平衡性、k次项系数、K次扩散准则(PC)、相关免疫 性(CI)、Walsh谱、代数次数、小项分布等方面得到了一批新结果。     

条形荷载下饱和均质地基曼德尔效应研究

本文通过研究biot固结理论,探讨了曼德尔效应产生的原因,并利用大型非线性有限元软件adina进行数值分析,得出条形荷载下饱和均质地基固结的数值解。并通过计算分析,得出了影响曼德尔效应的因素。     

孔型热轧时轧制力的实用计算公式

采用修正系数法,利用板材在带刻槽的冲头进行深冲与平面冲头下深冲时的接触压力的比值确定孔型影响系数,进而推导出孔型热轧时轧制力的实用计算公式.     

适用于稠油开采的游梁式抽油机设计分析

在稠油开采中,抽油杆在液体中运动时,所受到的摩擦阻尼力很大,有时高达几十千牛。上冲程时,该力有加大悬点载荷的作用;下冲程时,该力使抽油杆下行困难,甚至悬点载荷为零。为了开采稠油,必须根据其特点设计适应的游梁式抽油机。文章分析了稠油用抽油机的受力特点,提出了该类抽油机的设计要求。     

结构化P2P网络中基于流言传播的负载均衡

提出了结构化P2P网络中利用结点间周期性的拓扑维护通信来夹带、传播消息进行负载均衡的方法，具体针对Chord系统从消息传播的速度和规模两个方面分析了该方法的性能，并利用仿真进行了验证。讨论了结论在其它形式网络中的推广和实现中的消息管理问题。     

塔里木河流域源流及干流水均衡分析

通过对塔里木河流域源流及干流的径流变化和水均衡分析 ,表明塔里木河源流来水基本稳定 ,由于源流灌区引水以及渗漏蒸发等损失加剧 ,干流水量存在减少趋势 ,并加剧了水量的时间分配不均 ,不利于干流农业的可持续发展和生态环境的维护与改善     

Accurate higher-order analytical approximate solutions to nonconservative nonlinear oscillators and application to van der Pol damped oscillators

In general, this paper deals with general nonlinear oscillations of a nonconservative and single degree-of-freedom system with odd nonlinearity and, in particular, it presents accurate higher-order analytical approximate solutions to van der Pol damped nonlinear oscillators having odd nonlinearity and the Rayleigh equation. By combining the linearization of the governing equation with harmonic balancing and the method of averaging, we establish accurate analytical approximate solutions for the general weakly damped nonlinear systems. Unlike the classical harmonic balance method, simple linear algebraic equations instead of nonlinear algebraic equations are obtained upon linearization prior to harmonic balancing. The combination of these two methods results in very accurate transient response of the periodic solution. In addition and for the first time, this paper also presents a method for deducing fourth-, fifth- and higher-order linearized governing equations from the lower-order equations without the requirement of formulating the problem from the first principle. Three examples including the van der Pol damped nonlinear oscillator are presented to illustrate the excellent agreement with approximate solution using the exact frequency.     

Improved accuracy and convergence of discretized population balance for aggregation: The cell average technique

A new discretization method for aggregation equations is developed. It is compared to the fixed pivot technique proposed by Kumar and Ramkrishna (1996a. On the solution of population balance equations by discretization—I. A fixed pivot technique. Chemical Engineering Science 51, 1311-1332). The numerical results for aggregation problems by discretized population balances are consistently overpredicting and diverge before the gelling point in the case of a gelling kernel. The present work establishes a new technique which assigns the particles within the cells more precisely. This is achieved by taking first the average of the newborn particles within the cell and then assigning them to the neighboring nodes such that pre-chosen properties are exactly preserved. The new technique preserves all the advantages of the conventional discretized methods and provides a significant improvement in predicting the particle size distribution (PSD). In addition, it is found that the technique is a powerful tool for the computation of gelling problems. The effectiveness of the technique is illustrated by application to several aggregation problems for suitably selected aggregation kernels including physically relevant kernels.     

固定式塔吊基础设计与施工技术

潘家园小区工程建筑面积3．6万m^2，地下3层，地上28层。基槽标高-10.750m，地面至屋面女儿墙上口高度为83m，地上标准层层高2．8m。采用土钉墙护坡，坡度1：0．1，该工程的地质条件适宜桩基础的施工。