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.     

Optimal control and operation of drum granulation processes

Process optimisation and optimal control of batch and continuous drum granulation processes are studied in this paper. The main focus of the current research has been: (i) construction of optimisation and control relevant, population balance models through the incorporation of moisture content, drum rotation rate and bed depth into the coalescence kernels; (ii) investigation of optimal operational conditions using constrained optimisation techniques; (iii) development of optimal control algorithms based on discretized population balance equations; and (iv) comprehensive simulation studies on optimal control of both batch and continuous granulation processes. The objective of steady state optimisation is to minimise the recycle rate with minimum cost for continuous processes. It has been identified that the drum rotation-rate, bed depth (material charge), and moisture content of solids are practical decision (design) parameters for system optimisation. The objective for the optimal control of batch granulation processes is to maximize the mass of product-sized particles with minimum time and binder consumption. The objective for the optimal control of the continuous process is to drive the process from one steady state to another in a minimum time with minimum binder consumption, which is also known as the state-driving problem. It has been known for some time that the binder spray-rate is the most effective control (manipulative) variable. Although other possible manipulative variables, such as feed flow-rate and additional powder flow-rate have been investigated in the complete research project, only the single input problem with the binder spray rate as the manipulative variable is addressed in the paper to demonstrate the methodology. It can be shown from simulation results that the proposed models are suitable for control and optimisation studies, and the optimisation algorithms connected with either steady state or dynamic models are successful for the determination of optimal operational conditions and dynamic trajectories with good convergence properties.     

Crack Development in Individually Quick Frozen Cut and Peel Carrots

ABSTRACT:  Crack development during freezing (CDF) is one of the major challenges in individually quick frozen (IQF) cut and peel carrot processing. The effects of processing and freezer storage on crack development were examined on the cut and peel carrot variety, Sugarsnax. Carrot samples were removed from the major processing steps, the trans-slicer, the shaper, the blancher, and the dryer, and examined for crack development by measuring percentage cracked, crack morphology, total soluble solids, moisture levels, and membrane injury index immediately after processing. These parameters were also examined following 20 wk of standard freezer storage for cut and peels. Approximately 2% of nonprocessed carrots were cracked compared to 45% of carrots after the initial trans-slicing stage. As the processing continued, cracking decreased due to the removal of the outer epidermis to 16% of the finished product. This suggests that CDF was initiated at the 1st processing stage. Crack width and depth were 2.3 and 2.6 mm, respectively, at the trans-slicer stage and decreased to 1.1 and 1.8 mm at the end of the line. It was found that CDF was further exacerbated by freezer storage due to inefficient water removal at the dryer stage. Crack width and depth increased to 1.5 and 3.0 mm after 20 wk for freezer storage. Root size also played a role in CDF, suggesting that larger pieces are more susceptible to crack development. Total soluble solid concentrations did not play a role in crack formation during cut and peel processing.     

流量测量准确性的现场验证及其解决方案

流量计示值准确性的现场验证是交工验收的重要内容。介绍了现场校验法，质量平衡法，热量平衡法，设备能力法等流量测量系统的校验方法以及一些技巧。     

降低过滤机滤饼水分和细粒煤脱水浅析

根据对选煤厂细粒煤样的实验室优化脱水试验、工业试验及分析结果 ,对真空系统、气水分离器和分配头实施了技术改造 ,细粒煤脱水系统的运行状况得到显著改善 :圆盘真空过滤机滤饼水分降到 2 0 %左右 ,脱饼率在 95 %以上 ,每年的直接经济效益可达 30 0多万元     

Dynamics of Balancing Space and Time in Memory: Tau and Kappa Effects Revisited.

In 3 experiments, the authors studied the organization of spatiotemporal information in memory. Stimuli consisted of configurations of dots, presented sequentially. The stimuli were either proportional, with interdot distances corresponding to interdot durations, or not proportional, with interdol distances not corresponding to interdot durations. After a learning phase, participants reproduced the spatial (Experiment 1), temporal (Experiment 2), or spatial and temporal (Experiment 3) characteristics of the target 60 times in succession. In the nonproportional conditions, effects of variable interdot durations or distances on the reproduction of, respectively, constant distances (tau effect) or durations (kappa effect) were observed, whereas no such effects were observed when variable distances or durations were to be produced. Tau and kappa effects influenced the accuracy but not the variability of responses. The results are discussed in light of the distinction between properties of the stabilized mental image and the process of stabilization. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

砂岩储层渗透率表征方法探讨

渗透率是反映储层渗流能力的重要参数，目前对于单一储层的渗透率表征方法，通常是在岩心分析渗透率或测井解释渗透率的基础上进行厚度加权算术平均。这种方法对于均质的储层来说是适用的，但对于非均质严重的储层，不能准确反映该储层的实际渗流能力。本文提出一种应用可动流体体积权衡表征渗透率的方法，经实际资料验证，能较好地反映储层的实际渗透能力。