新围海涂土地利用结构优化模型及其应用

为了进一步探讨数学规划模型在新围海涂土地利用结构优化中的应用,在模型分析与实例应用相结合的基础上,选择浙江沿海新围海涂作为典型研究区,根据当地滩涂开发利用总体规划要求,结合实际开发需要,应用数学规划方法构建土地利用结构优化决策模型,对规划范围内新围海涂的土地利用结构进行优化配置。研究结论:应用数学模型对研究区内土地利用结构优化配置是可行的。但是今后需要进一步研究空间优化配置方法,实现定性、定量和定位三者的统一。     

Protecting Forests Through Farming. A Dynamic Model of Nontimber Forest Extraction

Forest resource extraction by local communities has been cited as a major impediment to the efficient management of protected forests. This paper develops a two sector dynamic model for farming and forest resource extraction by communities living in the forest periphery. The model assumes that land under forestry is constant and households allocate their time to farming and forestry. Comparative dynamic results suggest that higher prices for agriculture output, lower input prices, better knowledge of farming techniques and a lower discount rate may result in a higher equilibrium stock of forest resources. Tobit analysis with primary data collected from the Sinharaja forest in Sri Lanka provides supportive empirical evidence.     

岷江上游退耕还林的思考

岷江上游不仅是长江上游生态屏障障的重要组成部分，更是成都平原的重要生态屏障和水源生命线，该区拥有丰富的水、生物、旅游等可再生资源，但在退耕还林（草）生态建设中表现出退耕面积扩大化、国家补贴政策一刀切、经济林比重过大等问题。文章指出，应在克服上述问题基础上，通过调整农村产业内部结构、加大坡耕地改造、发展旅游业、水电业以及加强变通、通讯设施建设是实现经济可持续发展的最佳选择。     

我国土地征用制度探讨

国家为了公共利益的需要,可以依法对土地实行征用,但是这种征用必须符合公共利益、给予公平补偿、满足正当程序的要求。完善我国土地征用制度应该在这三个方面着手。     

城镇数字化地产评估系统及应用

城镇数字化地产评估系统是以“城市土地定级估价综合模型”作为主要评估方法 ,针对中小城镇地产评估的实际情况 ,基于Map/info平台 ,将多种应用程序集成而开发出来的。经实际使用 ,该系统操作简便 ,经济适用。     

A Semiparametric Method for Valuing Residential Locations: Application to Automated Valuation

This paper is motivated by automated valuation systems, which would benefit from an ability to estimate spatial variation in location value. It develops theory for the local regression model (LRM), a semiparametric approach to estimating a location value surface. There are two parts to the LRM: (1) an ordinary least square (OLS) model to hold constant for interior square footage, land area, bathrooms, and other structural characteristics; and (2) a non-parametric smoother (local polynomial regression, LPR) which calculates location value as a function of latitude and longitude. Several methods are used to consistently estimate both parts of the model. The LRM was fit to geocoded hedonic sales data for six towns in the suburbs of Boston, MA. The estimates yield substantial, significant and plausible spatial patterns in location values. Using the LRM as an exploratory tool, local peaks and valleys in location value identified by the model are close to points identified by the tax assessor, and they are shown to add to the explanatory power of an OLS model. Out-of-sample MSE shows that the LRM with a first-degree polynomial (local linear smoothing) is somewhat better than polynomials of degree zero or degree two. Future applications might use degree zero (the well-known NW estimator) because this is available in popular commercial software. The optimized LRM reduces MSE from the OLS model by between 5 percent and 11 percent while adding information on statistically significant variations in location value.     

我国农村土地制度的产权经济分析

近年来我国农村发生了土地制度的深刻变革,变革的核心是土地产权制度的变迁。这种制度变迁在某种程度上具有帕累托改进的性质,但在某些方面还有待于发展和完善。我国农村土地产权制度建设的思路:以现行产权制度为基础,通过修订和完善,不断发挥现行产权制度的积极作用。     

我国城镇建设有关土地制度创新研究

目前我国土地管理中存在着土地市场不完善．国土基金管理不到位等问题。应完善我国土地市场和加强国土基金使用管理。应加快土地资源的市场配置．完善国有土地有偿使用制度．推进国有土地使用权的招标、拍卖和挂牌出让。建立土地收购储备制度．以促进土地的可持续利用。完善城镇土地的出租制．采取长租、短租或临时出租等方式，以保证土地的长期收益。建立集体土地流转制度。成立国土基金专户．国土基金专款专用．收支两条线．实行国土基金的计划管理制度和监管制度。     

高硫减压渣油加工方案的技术经济比较

对中国石化齐鲁分公司高硫减压渣油两种生产方案,即减压深拔工艺生产重交沥青和VRDS-FCC组合工艺生产轻质油品进行技术经济比较.结果表明:在公司裂解原料不能完全自给的前提下,VRDS-FCC组合工艺的单位利润优于减压深拔工艺,但随着重交沥青价格的上升,VRDS-FCC组合工艺的优势将逐渐减弱.     

Anthropogenic and topographic correlates of natural vegetation cover within agricultural landscape mosaics in Turkey

Natural vegetation enhances the value of agricultural landscapes for people and wildlife. However, the role of anthropogenic versus topographic factors in driving the extent of natural vegetation cover within agricultural lands at large spatial scales remains unexplored. I assessed the influence of anthropogenic and topographic variables on the extent of agricultural mosaics with high natural vegetation cover in the country of Turkey where a large extent of natural and semi-natural vegetation is maintained by traditional agriculture. GIS layers depicting human land use, elevation, slope, roads and population data were obtained and summarized at two spatial scales, within provinces and for 100 km² grid cells covering the country’s entire agricultural land area. Average farm size was also obtained at province level. Hierarchical Partitioning was conducted to determine the independent effect of anthropogenic and topographic variables on the variation in agriculture with high natural vegetation. Slope had the largest independent effect on the variation in the proportion of agricultural mosaic with high natural vegetation cover. The extent of agricultural and settlement area also explained much of the variation in natural vegetation across both grid cells and provinces. The proportion of natural vegetation increased as human population and road density decreased across grid cells and as average farm size decreased across provinces. These results suggest that while topography is the primary driver of natural vegetation cover within agricultural mosaics in Turkey, the pressures associated with urban development and agricultural industrialization may also influence the cultural and wildlife value of agricultural landscapes.