Coordination between strategic forest management and tactical logistic and production planning in the forestry supply chain

In this paper, we study the coordination mechanism in the forestry supply chain between strategic forest management and tactical production planning. We first formulate an integrated model to establish a theoretical benchmark for performance of the entire supply chain. It is a mixed integer programming model that involves harvesting, bucking, transportation, production, and sales decisions for both tactical and strategic planning levels. We then present two sequential approaches S‐A and S‐B where the coordination is done through internal pricing. S‐A is the approach currently used in practice where harvesting in the forest is the main driver of the supply chain activities and internal pricing is introduced to control bucking decision in a separate stage. In contrast, S‐B takes downstream demand information into consideration and internal pricing directly influences harvesting decision in the first stage. In order to find the appropriate setting of internal pricing that leads to the system optimum, we suggest two heuristics H‐I and H‐II. The internal pricing in H‐I is based on dual values and in H‐II, it is derived from a Lagrangian decomposition. A real‐life case study in the Chilean forestry industry is used to compare the results of different approaches. It is shown that the new sequential approach S‐B generates as good feasible solution as that obtained from the integrated approach but in much less time. Both heuristics H‐I and H‐II bring about near‐optimal feasible solutions. H‐II also provides optimistic bound of the optimal objective function value, which can be used as a measure of the solution quality.     

Modeling of photocatalytic oxidation of VOCs in a packed bed reactor under continuous and discontinuous illuminations

In this paper, a mathematical model is presented to describe the photocatalytic degradation of VOCs in a packed bed reactor. Here, the adsorption of VOCs on the wall of the reactor is taken into account and the diffusion of VOCs in the axial direction is neglected. First-order kinetics is used to describe the photocatalytic oxidation of VOCs. The analytical solution of the present model is obtained by traveling wave method. The solution shows that the reactor performance is totally dependent on the inlet concentration of VOCs when the time is large enough. The present model is validated through the experimental result of the photocatalytic oxidation of trichloroethylene in a packed bed and the predicted results accord well with the experimental data. The influence of flow rate and inlet concentration on the performance of the reactor is discussed in detail. High flow rate offers high reaction rate and low conversion efficiency. The different inlet conditions and different reaction patterns are also investigated. The model would be useful to estimate the rate constant and help to the design of the reactor.     

数据加密技术在计算机安全中的应用

随着计算机网络技术的不断发展,计算机互联网在人们的生活中应用越来越广泛,网络安全问题也随之而来。目前的计算机安全存在着诸多因素的威胁,研究人员也在致力于这方面的研究与发展,应用先进的技术来保证计算机安全,为计算机用户的信息安全提供更高的保障。本文将针对计算机安全问题进行分析,探讨数据加密技术在计算机安全中的应用。     

无线传感器网络的路灯远程控制系统设计

本设计基于TI公司的CC2480/ZigBee开发系统,设计了无线控制平台,论证了网络的组成、软件流程以及节能模式,旨在提供一种基于ZigBee无线技术的城市路灯照明系统解决方案,从而设计出低成本、高效能、全自动化的城市照明系统。     

沥青带水磺化工艺的研究

通过沥青磺化过程的主反应和副反应，进一步讨论了磺化工艺的原理，磺化试剂的选择，溶剂的组成，带水速度，溶剂的回收方式等各种因素对产品质量的影响。     

A novel and versatile method for the synthesis of soluble fullerenated polymers

Summary A new route for the preparation of soluble fullerenated polymer through the reaction of carbanion intermediates of polymers with fullerenes, particularly C₆₀, is demonstrated. Confirmation of the covalent attachment of C₆₀ to the polystyrene backbone is by a variety of techniques such as UV-Vis, FT-IR, TGA, SEM and ¹³C NMR etc. The product, which has a visibly brownish yellow cast when compared with the unreacted polymer, is soluble in some common organic solvents. The thermal stability of pure polystyrene is enhanced by C₆₀-chemical modification, and no bonds within the carbon sphere are broken.     

基于Creator的战场地形仿真研究

如何解决地形模型精细度、逼真度与仿真速度之间的矛盾是军事仿真的难点问题。本文研究了三维地形生成的关键技术,并详细阐述了利用MultiGen Creator建模工具,采用DEM数据和卫星遥感影像数据构建和优化大面积战场地形的原理和方法,最后结合实例生成战场地形。仿真结果表明,该方法生成的模型达到了精细度高、真实感强、实时性好等仿真要求。     

Evaluation of group effect of pile group under dragload embedded in clay

A simple semi-empirical analysis method for predicting the group effect of pile group under dragload embedded in clay was described assuming an effective influence area around various locations of pile group. Various pile and soil parameters such as the array of pile group, spacing of the piles (S), embedment length to diameter ratio of piles (L/D) and the soil properties such as density (γ), angle of internal friction (φ) and pile-soil interface friction coefficient (μ) were considered in the analysis. Model test for dragload of pile group on viscosity soil layer under surface load consolidation conditions was studied. The variations of dragload of pile, resistance of pile tip and the layered settlement of soil with consolidation time were measured. In order to perform comparative analysis, single pile was tested in the same conditions. The predicted group effect values of pile group under dragload were then compared with model test results carried out as a part of the present investigation and also with the values reported in literatures. The predicted values were found to be in good agreement with the measured values, validating the developed analysis method. The model test results show that negative skin friction of pile shaft will reach 80%–90% of its maximum value, when pile-soil relative displacement reaches 2 mm. Foundation item: Project(50679015) supported by the National Natural Science Foundation of China     

Effects of a strong polyelectrolyte on the rheological properties of concentrated cementitious suspensions

Strong polyelectrolytes, referred to as superplasticizers, are known to improve the initial fluidity of concentrated cement suspensions. To quantify how the polyelectrolytes affect the fluidity, we have studied the effect of a strong anionic polyelectrolyte, melamine formaldehyde sulfonate (MFS), on the zeta potential of cement particles and on the steady-shear and low-amplitude rheological properties of cement suspensions. Adsorption of low concentrations of MFS onto the cement particles leads to an inversion in the sign of the surface potential, causing the electrostatically flocculated particles to become electrostatically dispersed and giving rise to a corresponding decrease in the steady-shear viscosity and storage modulus. At an intermediate MFS concentration, the steady-shear viscosity and the storage modulus each display a minimum. This concentration corresponds to that at which the zeta potential becomes constant. Larger concentrations of MFS result in an increase in the viscosity and storage modulus, which is attributed to depletion flocculation. These results thus relate the interaction between particles to the suspension fluidity through the analysis on the surface potential of particles and microstructure of suspension.     

基于VB和AutoCAD的纸盒辅助设计系统

在总结现有盒型特点并对其进行科学分类的基础上,结合Visual Basic语言与AutoCAD各自优势,开发具有盒型结构的参数化设计、材料使用率与消耗量、数据存储采集等功能的包装纸盒设计系统,达到提高绘图效率,简化开发过程,实现优化设计的目的。