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.

Can farmers extend their cultivation areas in urban agriculture? A contribution from agronomic analysis of market gardening systems around Mahajanga (Madagascar)

The rapid urbanization in developing countries implies an increasing pressure on urban agriculture for production. As most perishable food products come from this agriculture in close proximity to population concentrations, we analysed from an agronomic point of view how market-garden farmers can meet this increasing urban demand. This work took place in the case of Mahajanga, a secondary city with high increasing demographic rate on the Northwest coast of Madagascar. Based on preliminary surveys to characterize the farming systems (on a sample of 91 farms), 11 market-garden farmers chosen in the three main agricultural zones of the urban area were surveyed during two years. Surveys aimed at understanding their decision rules in crop choices, crop allocation to land and resource management, and to estimate their room for manoeuvre to increase their leafy vegetable areas under cultivation. The wholesalers and retailers who buy the farmers’ produce were also surveyed. A previous model of decision rules regarding crop location on farm territory was used to analyse the on-farm surveys and cartographic methods (GIS and on-farm manual representations) were used to quantify the land use. We highlight the following major points. (1) The leafy vegetable production in the surveyed farms already intensively uses land: farmers have complex decision rules largely depending on the water dynamics in the two main environments (lowlands and lakesides) where leafy vegetables are cultivated during the dry season. (2) The scarcity of farmers’ resources (labour money and water) leads to very little internal room for manoeuvre to increase the leafy vegetable production in the farms. (3) At territorial level however, some land reserve exist in one of the lowlands, but not on lakesides. The water availability for agriculture must be better informed through specialized hydrologic studies, as one of the main constraints nowadays to extend the agricultural area. An extrapolation to other cases of urban agriculture is then discussed as well as the role of agronomy to help urban planners to consider the place of agriculture in the urban development.     

基于球谐变换的无人机蜂群RCS快速分析算法

为了获取目标的雷达截面积(Radar Cross Section,RCS),传统的方法是采用矩量法（Method of Moment,MOM）或多层快速多极子方法(Multi-level Fast Multipole Algorithm,MLFMA),尽管对目标的RCS计算精确,但其要求计算机的存储量大且计算耗时。而对于由上百成千个小型无人机组成的无人机蜂群而言,若采用上述方法来计算其RCS,计算量巨大,甚至无法计算。针对上述问题,提出了采用球面波展开技术与球谐变换相结合的方法来提升对无人机蜂群RCS的仿真效率,其关键技术是通过改变球谐函数中的求和次序,利用快速傅里叶变换来计算偏心球面上离散点的电场分布。数值实例表明,相比于高精度的MLFMA,所提方法获取蜂群无人机RCS的结果与其吻合良好,但对计算机内存的需求远远小于MLFMA,且随着无人机数量的增加,其计算速度可提升几个数量级。     

Do satisfying walking and cycling trips result in more future trips with active travel modes? An exploratory study

Previous studies have indicated that travel satisfaction - the experienced emotions during, and cognitive evaluation of, a trip - can be affected by travel mode choice and other trip characteristics. However, as satisfactory trips might improve a person's attitude towards the used mode, persons may be more likely to use that same mode for future trips of the same kind. Hence, a cyclical process between travel mode choice and travel satisfaction might occur. In this paper we begin to analyse this process—using a structural equation modelling approach on cross-sectional data—for people who engage in walking and cycling for leisure trips in the Belgian city of Ghent. The focus on walking and cycling reflects recent studies indicating that active travel is often associated with the highest levels of travel satisfaction. Results of this exploratory analysis offer tentative support for the idea of a cyclical process: the evaluation of walking and cycling trips positively affects the respondents' attitude towards the respective mode, which in turn has a positive effect on choosing that mode.     

Interpretive structural modeling of quality factors in both medical and hospitality services in the medical tourism industry

This study aims to theoretically integrate quality factors of both medical and hospitality services in medical tourism. Medical tourism comprises both medicine and tourism. Although the core product in medical tourism is medical treatment, attractive hospitality and travel options are also essential. Despite the dual nature of medical tourism, the two aspects of this concept have not been integrated in a unique framework. This study attempts to fill this gap using interpretive structural modeling (ISM). According to ISM, although factors of medical services and hospitality services are independent from each other, these factors have vital impacts on perceived value, satisfaction, and loyalty.     

An integrated approach for ex-ante evaluation of public policies for sustainable agriculture at landscape level

An integrated methodological framework for ex-ante evaluation and planning of public policies for sustainable agriculture at agro-landscape level is proposed. The components of the framework are to: (1) determine the private, i.e. farmers’, and public benefits associated to agro-landscapes, consisting of an agricultural land-use system, according to its performance for several market and non-market functions. Market forces determine the market benefits and preferences of society the non-market benefits; (2) explore and select potential sustainable agro-landscapes based on the private and public benefits associated with possible land-use alternatives; (3) define efficient public policy mechanisms for improving social net benefit of agro-landscapes.The framework is illustrated with a case study in a small dairy farming dominated agro-landscape in The Netherlands, with gross margin, landscape quality, nature value and environmental health as the analysed ecosystem functions. Alternative landscapes consisting of hedgerow configurations and grassland management practices were explored, yielding a set of alternatives representing the solution space in terms of change in private and public benefits. Policy mechanisms were defined to move from the current to a desired landscape based on changes in social net benefits. Moreover, the necessity of a modification in the current agri-environmental support was analysed for each landscape. The analysis considered all farmers in the agro-landscape jointly. The results for the case study showed potential prototypes of landscapes and their performance compared to the current landscape. Extension was the most efficient policy mechanism to promote the change to the socially optimum landscape alternative.     

土地利用变化驱动力多尺度因素的定量影响分析

研究目的:揭示多尺度土地利用变化研究中尺度因素对驱动力的定量影响。研究方法:构建Logistic回归模型和二分类反应变量两水平Logistic回归模型,分别基于面向尺度对比的多尺度回归分析和基于系统观点的多水平模型分析两个角度,探讨多尺度土地利用变化核心驱动力及其定量影响关系,并对两类模型的分析结果进行对比分析。研究结果:面向尺度对比的多尺度回归分析法能够从更为微观的角度揭示各个尺度层级上地类变化的核心驱动因子,而基于系统观点的多水平模型分析方法则能够更好地顾及尺度因素的定量影响。研究结论:多水平模型分析方法揭示的各个地类的核心驱动因子集与多尺度回归分析法推导的对应地类的核心驱动因子集之间呈现子集关系,两者在多尺度土地利用变化驱动力的研究方法上能够形成互补。     

Using stated preference techniques to value four key ecosystem services on New Zealand arable land

Many researchers have noted that not only natural ecosystems but also landscapes actively modified by humans (engineered or designed ecosystems) can significantly impact the level of ecosystem goods and availability of services, thereby impacting human and social welfare. In New Zealand, agricultural lands are the largest area of engineered ecosystems on the national landscape. Study of the welfare effects of ecosystem services delivered by agricultural land can provide important insights into the management of engineered or designed ecosystems. This paper uses the contingent valuation method (CVM) and choice modelling to estimate values of four key ecosystem services: climate regulation, water regulation, soil retention and scenic views, for New Zealand land used for arable farming.     

A Socio‐Psychological Perspective on Team Ambidexterity: The Contingency Role of Supportive Leadership Behaviours

In addressing the notion of team ambidexterity, we propose that socio‐psychological factors (i.e., team cohesion and team efficacy) may help team members to resolve paradoxical challenges and to combine exploratory and exploitative learning efforts. In addition, we theorize that senior executives may play an important role in facilitating the emergence of ambidexterity at lower hierarchical levels. In doing so, we develop a multilevel contingency framework and propose that the effectiveness of teams to achieve ambidexterity is contingent upon supportive leadership behaviours at the organizational‐level. Using multilevel, multisource, and temporally separated data on 87 teams within 37 high‐tech and pharmaceutical firms, we not only reveal how team cohesion and efficacy may matter for the emergence of team ambidexterity but also show that the effectiveness of supportive leadership behaviours from senior executives varies across cohesive and efficacious teams.     

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。