两个层面——风景园林规划设计中的艺术语言研究

在分析风景园林规划设计中艺术语言的两个层面-潜性艺术语言和表性艺术语言后，提出了园林规划设计作为造型艺术作品的一种形式，受到了艺术语言制约的观点，丰富了设计师在造园实践中的艺术语言，强调了营造高格调的优秀园林，依赖于设计师对园林艺术语言的整体表达和娴熟运用。     

Financial optimisation of target diameter harvest of European beech (Fagus sylvatica) considering the risk of decrease of timber quality due to red heartwood

A mature, average stand of European beech was generated based on characteristic data of trial plots. Some 27 different strategies of target diameter harvest, were simulated for up to 80 years with the help of a distance-dependent single-tree growth simulator. The treatments were differing in the size of the target diameter, the beginning and the end of the harvest. Based on a statistical model, the probability of the occurrence of more than 30% of red heartwood at the front-side diameter was calculated for three sections of each log. Using the predicted probability, the decrease of timber quality due to red heartwood for different treatment strategies was assessed. The harvested volume and the predicted timber quality for different harvesting strategies were used to calculate the net revenue achieved in each simulation period with the help of a calculation program. The net present value for variable interest rates of the different harvesting strategies was calculated, assuming free land rent. Using a linear programming approach, optimal areas for different treatment strategies of a modelled forest of 100 ha were calculated under 4 different scenarios. The results of the optimisation showed how the increasing interest rates replaced higher target diameters out of the optimal solution. In contrast to that the treatments with higher target diameter became more important with increasing restrictions concerning budget or ecological constraints.     

基于VB的缆索吊装设计系统

以缆索吊装理论为基础,对缆索在桥梁施工中的吊装作业情况进行分析,建立缆索吊装设计数学模型,利用Visual Basic6．0实现系统设计。系统界面友好,操作简便,改变了繁琐的人工计算过程。实现了给定参数输入,通过计算可以得到主索、起重索、牵引索、风缆索、塔架、地垄及绞盘机功率等精确的设计结果,可为缆索吊装设计提供科学依据。     

Planning optimal economic strategies for agroforestry systems

Design of agroforestry systems requires a land management planning process that clearly specifies wants, needs and objectives along with the land's suitability for potential agroforestry practices. Within this planning process economic analysis can be used to analyze agroforestry alternatives to help determine the proper system to apply. Specifically, production economics coupled with capital theory and valuation techniques can provide measures of economic performance in terms of present net values, benefit-cost ratios and internal rates of return. These economic performance measures can be used to determine the best joint production level for a particular agroforestry practice. Once these best combinations have been defined, linear programming can be applied using these best joint production combinations as decision variables along with considering a wide range of additional constraints and requirements. A hypothetical example is used to illustrate the planning process and how these economic tools can be combined as a package to help determine optimal agroforestry strategies.     

Optimal harvest scheduling in Eucalyptus plantations: A case study in Galicia (Spain)

This paper focuses on strategic management planning of Eucalyptus globulus Labill. plantations in Galicia (northwestern Spain). Several problems associated with the management of these plantations were identified first. Current management plans for plantations of this species consist of the systematic and somewhat arbitrary application of the area control method. Thus, these plans do not take into consideration the optimum length for one full plantation cycle that maximizes the land expectation value, neither do they formulate the area control method through any mathematical programming model for scheduling regeneration harvests. In this paper, we present a modelling approach based on linear and goal programming. The models consider area and volume control regulation strategies, and take into account variations in land productivity among site classes and successive rotation intervals. To illustrate this approach, we applied the models to a neighbourhood community-owned forest currently managed by the Regional Forest Service with a recent management plan. The results showed that the models provided more flexible harvest schedules, and the profitability of eucalypt stands was 64% higher than that under the current management plan. Finally, extensions to this study were identified.     

Agroforestry,attitude towards risk and nutrient availability: a case study of south Indian farming systems

Introduction of two systems of agroforestry to the farmers portfolio is evaluated for their changes in cropping pattern, input use, income generation, farmers attitude towards risk and nutrient availability. Two different types of farmers are studied under both irrigated and dryland farming systems. Farm survey data collected from south Indian villages have been used with a mean-variance framework to identify the risk aversion levels of farmers. The results indicate that the risk-taking preferences of farmers should be given consideration in evaluating the impact of agroforestry systems. Among the two agroforestry systems analyzed, the one with drumstick is shown to increase the risk of crop production while the one with leucaena reduces the risk and enables farmers to invest in more risky cash crops. The impact of agroforestry on crop allocation, input use and income differs due to the differences in resource availability of farmers. The influence of agroforestry on nutrient availability of the farm households also differs based on the components of agroforestry, orientation of farming and the nature of farming systems. It is argued that design of agroforestry systems should consider differences in resource constraints in farming systems and risk attitudes of farmers towards their allocation decisions and that such considerations would largely enhance the successful adoption of agroforestry in developing countries.     

太行山南部片麻岩山地林果生态经济系统工程模式

本文在小流域综合治理试验研究基础上,根据影响林果树木成活和生长发育的主导因素,对河北省片麻岩山地划分了土地类型和小流域类型;采用系统工程的方法,通过微型计算机运算选择最优方案,研究了山地林果的合理布局、科学营造和管护,得出使生态效益和经济效益同步增长的生态经济系统工程模式。     

The potential of agroforestry in the high rainfall areas of Zambia: a peasant programming model approach

Existing cropping systems in Northern Zambia cause deforestation and soil degradation. To reduce the environmental problems, the potential of alley cropping and pigeon peas replacing the existing cropping systems was analyzed by the use of multi-objective programming models of peasant households. The models were formulated based on the theories of Chayanov and Nakajima which are suitable under conditions of imperfect labour markets. Risk was incorporated in the models in relation to weather and fertilizer supply. The models provide an opportunity to relate key characteristics of new technologies to key characteristics of peasants' preferences and resource constrains. The models may also be used to identify minimum performance levels required for new technologies to be found acceptable.Models of a small male-headed household are presented under varying conditions: for high and low population densities, with and without fertilizer subsidies, and for households with and without access to off-farm employment under high population density conditions.The analysis showed that the alley cropping technology is very unlikely to replace thechitemene system where there is still sufficient woodland for its continuation. The technology may have higher potential in more densely populated areas, where more intensive forms of agriculture are practised and where there is access to inputs such as lime and fertilizer. The removal of fertilizer subsides as a result of the Structural Adjustment Programs, may favour alley cropping because this technology may increase the efficiency of fertilizer use and reduce the need for nitrogenous fertilizers. The potential of the technology depends very much on the management level and location-specific performance of the trees.The pigeon pea technology has high potential if it is accepted as food since it has a very favourable yield per unit of labour, requires no monetary inputs, and can grow, in very poor soils. Pigeon pea also has potential as a cheap source of protein for the urban poor.     

浅谈工厂景观中生态理念的应用

湛江“奥里油”发电厂是我国唯一的利用特殊燃料发电的项目,投资巨大,而且地处孤岛之上,环境特殊。厂区地处海边,受海风吹袭,土壤稀薄,又毗邻火力发电厂,受烟尘废气的污染。考虑到厂区形象及周围的特殊环境,工厂景观中应用生态理念,采用电厂特有的景观语言及景观生态规划的手法,将场区废弃物组织到景观中,使得湛江“奥里油”发电厂的景观特色鲜明,生态环保,营建可持续景观。     

德阳市东山片区城市森林规划探讨

针对德阳市东山片区城市森林的现状和存在问题,提出了德阳市东山片区城市森林规划的指导思想,规划原则和目标,阐述了东山片区"二网六区多核"的布局结构,并详细规划了生态休闲区、风景林区、宗教文化区、生态旅游区、水土保持林区、生态农业观光区、庭院经济区、道路林网和农田林网。