精密车床主轴计算机辅助设计

将普通车床主轴运动机构视为由四个轴组成,每个轴视为分别装有齿轮和轴承等零件的一个子结构的装配体,利用Pro/E分别建立各子结构的三维实体模型,通过对各子结构装配实现对整个车床主轴传动的三维建模,利用Pro/E软件的Mechanism模块对整个机构进行运动学分析和运动仿真。既保证了车床主轴传动的准确性,也大大提高了设计效率。利用该方法可以使得设计人员快速、直观的对普通车床主轴运动机构进行优化设计,降低机床的研发成本,提高机床的可靠性。     

Integrated water and economic modelling of the impacts of water market instruments on the South African economy

A static computable general equilibrium model of South Africa is adapted to compare new taxes on water demand by two industries, namely forestry, and irrigated field crops. Comparisons are made with respect to both the short and the long run, in terms of three target variables, namely (i) the environment; (ii) the economy; and (iii) equity. Since the taxes on the two industries do not raise the same amount of revenue, the target variables are calculated per unit of real government revenue raised by the new taxes (also referred to as the marginal excess burdens of the taxes). The model results are robust for moderate values of the water elasticity of demand in the two industries, in both the long and the short run. The tax on irrigated field crops performs better in terms of all three the target variables in the short run. In the long run the tax on irrigated filed crops is better in terms of water saving, but reduces real GDP and the consumption by poor households.     

An empirical study of collaborative partnering among enterprises and government organizations for information system outsourcing

Most researches on information systems (IS) outsourcing indicate that public sector decides to outsource information technology (IT) services due to the belief that private vendors offer more cost advantages. This research explores government sectors of outsourcing and focus on the role of relationship for IS-service providers. Quantitative data of 126 questionnaires and 30 IS demonstrate that trust, mutual dependence, equipment investment and information sharing are contributing factors to successful outsourcing long-term partnerships. Information sharing between the service receiver and provider is also vital in terms of equipment investment in long-term partnerships, and is affected by the level of trust that each party holds for the other within the outsourcing process. Conceptual model is useful in explicating important government-business partnering strategies – the model highlights not only the economic benefits that the IS-outsourcing relationship brings based on social exchange theory characteristics, but also suggests many additional relevant elements.     

How may a carbon tax transform Australian electricity industry? A CGE analysis

The carbon tax policy proposed by Australian government has triggered deep concerns about the high electricity prices facing households and the sustainability of electricity industry. By employing a computable general equilibrium (CGE) model and an environmentally extended Social Accounting Matrix (SAM), this article simulates the effect of Australian carbon tax on the electricity industry. The modelling results show that the wholesale electricity prices indeed increase by about 90%, but the retailer prices only increase by 25%. The coal-fired electricity generators will reduce their output by 8% (for black-coal) to 18% (for brown-coal), but the profitability of the industry will drop dramatically. On the other hand, generators using oil, gas or renewable resources, will increase their output significantly and enjoy a handsome profit. Through the price, cost and profitability mechanisms, the carbon tax will transfer the Australian electricity generation to a low emission industry in the long term.     

Irbesartan and amlodipine in the treatment of patients with microalbuminuria,hypertension and type 2 diabetes in Taiwan: a modelling projection over 25 years

Summary

This modelling study aimed to evaluate the long-term cost effectiveness of four treatment strategies: early irbesartan; late irbesartan; amlodipine; and standard hypertensive treatment in patients with diabetes, hypertension and microalbuminuria in Taiwan. A Markov model was used to project costs and clinical outcomes over lifetimes.

Early irbesartan (initiated in microalbuminuric patients) yielded the largest improvements in life expectancy (0.78 years) compared with standard treatment. Late irbesartan and amlodipine (started in patients with overt nephropathy) also resulted in slight improvements in life expectancy (0.109 and 0.001 years, respectively). Both early and late irbesartan reduced lifetime costs compared with control (US$7,603 and US$3,233, respectively), whereas amlodipine increased lifetime costs by US$300. Improvements were attributed to reductions in the cumulative incidence of end-stage renal disease with early use of irbesartan.

Treating hypertensive diabetic patients with early irbesartan was projected to be life extending and cost saving, and to reduce the incidence of ESRD in Taiwan.     

Data-based mechanistic modelling and forecasting globally averaged surface temperature

The main objective of this paper it to model the dynamic relationship between global averaged measures of Total Radiative Forcing (RTF) and surface temperature, measured by the Global Temperature Anomaly (GTA), and then use this model to forecast the GTA. The analysis utilizes the Data-Based Mechanistic (DBM) approach to the modelling and forecasting where, in this application, the unobserved component model includes a novel hybrid Box-Jenkins stochastic model in which the relationship between RTF and GTA is based on a continuous time transfer function (differential equation) model. This model then provides the basis for short term, inter-annual to decadal, forecasting of the GTA, using a transfer function form of the Kalman Filter, which produces a good prediction of the ‘pause’ or ‘levelling’ in the temperature rise over the period 2000 to 2011. This derives in part from the effects of a quasi-periodic component that is modelled and forecast by a Dynamic Harmonic Regression (DHR) relationship and is shown to be correlated with the Atlantic Multidecadal Oscillation (AMO) index.     

The effect of external supply knowledge acquisition,development activities and organizational status on the supply performance of SMEs

Given the increasingly strategic role of external resources, acquiring knowledge about current suppliers and the broader supply market is an important and demanding task for the purchasing and supply management (PSM) function of a firm. Performance-improvement-oriented application of external supply knowledge present further challenges for the function. To examine this, we draw on the knowledge-based view and develop a hypothesized model in which supply knowledge acquisition drives PSM exploration and exploitation orientations which in turn mediate the organizational status of PSM function in terms of supply performance. We test the model on an SME-focused and survey-based dataset, using structural equation modelling. Our results indicate that an exploitative orientation is associated with knowledge gained from the supply base, whereas an explorative orientation is predominantly associated with supply market knowledge and less with supply base knowledge, suggesting natural pairings. The findings also show how an exploitative development orientation mediates the positive association of the PSM function's organizational status with supply performance. Driven by supply base knowledge, a status-empowered exploitative PSM orientation may suppress supply market based explorative orientation in resource-scarce SMEs, thus appearing to serve as the sole path to supply performance. Our research contributes by pointing out the significance of the knowledge-resource, and the knowledge-based view, in understanding performance in PSM.     

基于主体建模方法及其在宏观经济学中的应用

本文介绍了一种新型宏观经济学研究范式———基于主体建模方法。与主流的动态随机一般均衡模型相比,基于主体建模方法能更好地描述实际生活中经济主体的有限理性和适应性预期的行为,同时它还可以模拟复杂性系统中的异质性主体之间的交互作用,从而研究经济系统的演化过程及其宏观特征的“涌现”过程。此外,本文还介绍了基于主题建模方法在货币政策和经济波动理论中的应用：在政策分析中,基于主题建模方法能大量模拟市场参与者决策的“动物精神”和“羊群效应”,即使没有外部冲击,也可能形成金融危机等非均衡经济现象。随着计算机水平的发展,基于主题建模方法必将成为经济学分析的一个有力的新工具。     

Complexity and the limits to learning

In this paper we look at the manner in which ideas coming from complexity science change our understanding of the cognitive powers of agents that is really necessary to explain the evolution of markets and of firms. The general ideas behind complex systems dynamics and evolution are presented and then two examples are treated in detail. The first in an evolutionary model of a market in which some new product is developed by competing firms and their “task” is to find a strategy in terms of quality and price that will be sustainable. This essentially requires agents/firms to discover mutually compatible strategies, and to create thereby sustainable market niches. The second example considers the internal structure of firms, in terms of their constituent working practices and skills. It demonstrates that it is precisely their ignorance of the consequences of adopting any particular practice that generates diversity in the emergent capabilities of firms, exploring the dimension of potential demand and therefore leading to a successful and sustainable business sector. The work supports the notion that the cognitive abilities that are involved are not about deduction and logic, as a traditional view of rationality might suggest, but are about the development and contraction of interpretive frameworks, which will be different for each player. The paper links these examples to a general recognition of the idea that complex, multi-agent systems evolve through successive “structural attractors”—multi-dimensional dynamical systems—with temporary structural stability. Because real systems contain both the structure and deviations from it, then there is a constant probing of structural stability and the possibility of qualitative change to a new structural attractor. This resembles the ideas in biological evolution related to “punctuated equilibria,” but it also links this to the idea of emergent and evolving networks of interaction, never of course near thermodynamic equilibrium.      

Property rights and information flows: a simulation approach

With the growth of the information economy, the proportion of knowledge-intensive goods to total goods is constantly increasing. Lessig (The future of ideas: the fate of the commons in a connected world. Vintage, New York 2001) has argued that IPRs have now become too favourable to existing producers and that their ‘winner-take-all’ characteristics are constraining the creators of tomorrow. In this paper we look at how variations in IPRs regimes might affect the creation and social cost of new knowledge in economic systems. Drawing on a conceptual framework, the Information Space or I-Space to explore how the uncontrollable diffusibility of knowledge relates to its degree of structure, we deploy an agent-based modelling approach to explore the issue of IPRs. We take the ability to control the diffusibility of knowledge as a proxy measure for an ability to establish property rights in such knowledge. Second, we take the rate of obsolescence of knowledge as a proxy measure for the degree of turbulence induced by different regimes of technical change. Then we simulate the quantity and cost to society of new knowledge under different property right regimes.