Stabilizing employment in a fluctuating resource economy

We consider a resource management problem in which the management objective is to minimize fluctuations in resource economics. Stabilizing management policies consist of memoryless state feedback control strategies for a class of discrete-time resource models which contain unknown but bounded fluctuations. The underlying theory is based on conditions developed for Lyapunov-type stability of sets. The design of the stabilizing policies is illustrated by a simulation example from resource economics. Specifically, employment of fishermen is stabilized by using a subsidizing and taxing policy in an open-access common-property fishery in which the value of the resource and the resource level fluctuate, and where entry and exit dynamics are determined by fluctuating revenues obtained from the fishery.This work was supported by NSF and AFOSR under Grant No. ECS-86-02524.The support by the Yrjö Jahnsson Foundation is greatly acknowledged.     

微机刚体转动惯量测定系统

本文介绍了微机刚体转动惯量测定系统的原理及实现方案，并指出在现有实验设备的基础上提高实验教学质量的方法和途径。     

SEQUENTIAL FISHING: COOPERATIVE AND NON-COOPERATIVE EQUILIBRIA

Two agents control the areas in which a migrating fish stock is located. The harvesting is sequential. The stock available to Agent 1 depends on the growth of the stock, which in turn depends on the amount left after harvesting by Agent 2. The stock available to Agent 2 is the quantity left after harvesting by Agent 1. Each agent fishes down the stock in each period to an “abandonment level” deemed appropriate. The problem is analyzed as a noncooperative versus cooperative, repeated game with an infinite time horizon. In the noncooperative solution, both agents will harvest the stock if the unit cost of Agent 2 is not too much higher than the unit cost of Agent 1. A cooperative solution supported by a threat to revert to the noncooperative solution if deviation occurs implies greater differences in unit costs at which both agents will harvest the stock. The problem is illustrated by a simple, numerical example.     

Initial basis for a national planning model

Analysis of pending national policy takes on greater importance each day to supply policy makers with much needed data on the overall economic effect such policies will have on total employment, income, output, tax revenues, and the general price level throughout the economy. This short paper examines the potential for integration of existing modeling technology into a meaningful national planning model to provide a sound set of economic indices leading to enhanced market efficiency and resource use. Initial efforts at integrated modeling and analysis are described, together with indications of their levels of success in replicating the existing economic environment. Emphasis is placed on determination of shadow prices in a growing economy and their incorporation into the systematic development of a national planning model.     

Theory of GC2 — an unusual approach

In contrast to traditional theoretical approaches by calculation of (nonexistent) theoretical plates, a unified theory of gas chromatography as given by a definition of the resolution analogue to methods in signal processing or spectroscopy using the well-known Kovacz indices as fundamental scale. A derivation of the thusly defined resolution from basic physical principles yields very practical formulae for peak width, maximum load, substance flow in peak maximum, concentration of substance in the carrier gas and other interesting parameters in dependence of capillary diameter, capillary length, film thickness, carrier gas speed, viscosities etc. Diagrams show favourite conditions for detectors responding on absolute substance flow (e.g. FID) or on concentrations.     

Enhancing profitability of dry mill ethanol plants

An Aspen Plus™ modeling platform was developed to evaluate the performance of the conversion process of degermed defibered corn (DDC) to ethanol in 15- and 40-million gallons per year (MGPY) dry mill ethanol plants. Upstream corn milling equipment in conventional dry mill ethanol plants was replaced with germ and fiber separation equipment. DDC with higher starch content was fed to the existing saccharification and fermentation units, resulting in higher ethanol productivity than with regular corn. The results of the DDC models were compared with those of conventional dry mill ethanol process models. A simple financial analysis that included capital and operating costs, revenues, earnings, and return on investment was created to evaluate each model comparatively. Case studies were performed on 15- and 40-MGPY base case models with two DDC process designs and DDC with a mechanical oil extraction process.     

Extractive fermentation of acetic acid

In this technoeconomic evaluation of the manufacture of acetic acid by fermentation, the use of the bacterium:Acetobacter suboxydans from the old vinegar process was compared with expected performance of the newerClostridium thermoaceticum bacterium. Both systems were projected to operate as immobilized cells in a continuous, fluidized bed bioreactor, using solvent extraction to recover the product. Acetobacter metabolizes ethanol aerobically to produce acid at 100 g/L in a low pH medium. This ensures that the product is in the form of a concentrated extractable free acid, rather than as an unextractable salt. Unfortunately, yields from glucose by way of the ethanol fermentation are poor, but near the biological limits of the organisms involved.     

基于分形动力学过程的腐蚀预测模型

腐蚀是一种复杂随机现象,可以用分形理论更好地描述。本文根据分形动力学过程,以一组基于不同表面条件下的腐蚀发生概率为参数,建立计算机模型来预测大气、土壤环境的金属腐蚀过程。计算结果和实际腐蚀特征吻合一致。此外,本文还讨论了幂函数腐蚀模型中指数n和各种腐蚀概率之间的定量关系,揭示了腐蚀发展规律。     

基于真实情境的化学综合实践活动设计

针对真实情境素材进行分析，提炼实践活动主题，围绕“炼铜厂对环境能否产生污染”这一问题情境设计化学综合实践活动。通过学习炼铜的相关知识，引导学生分析污染产生的原因，了解“三废”的处理方法，培养学生的环保意识；通过学习炼铜的工艺流程，使学生了解实际生产过程的复杂性，培养学生的工程意识。通过角色扮演的职业体验，让学生体会学习化学的重要性，培养学生的参与意识和决策能力。     

Stabilization and Practical Asymptotic Stability of Abstract Differential Equations

This article studies the problem of stabilization of the infinite-dimension time-varying control systems in Hilbert spaces. We consider the problem of practical asymptotic stability with respect to a continuous functional for a class of abstract nonlinear infinite-dimensional processes with multivalued solutions on a metric space when the origin is not an equilibrium point. In the case of the existence of a differentiable Lyapunov functional, we obtain sufficient conditions for the practical stability of continuous semigroups in a Banach space.