Forecasting the Ethiopian Coffee Price Using Kalman Filtering Algorithm

Ethiopian coffee price is highly fluctuated and has significant effect on the economy of the country. Conducting a research on forecasting coffee price has theoretical and practical importance.This study aims at forecasting the coffee price in Ethiopia. We used daily closed price data of Ethiopian coffee recorded in the period 25 June 2008 to 5 January 2017 obtained from Ethiopia commodity exchange (ECX) market to analyse coffee prices fluctuation. Here, the nature of coffee price is non-stationary and we apply the Kalman filtering algorithm on a single linear state space model to estimate and forecast an optimal value of coffee price. The performance of the algorithm for estimating and forecasting the coffee price is evaluated by using root mean square error (RMSE). Based on the linear state space model and the Kalman filtering algorithm, the root mean square error (RMSE) is 0.000016375, which is small enough, and it indicates that the algorithm performs well.     

A data model and algorithms for a spatial data marketplace

A data marketplace is a platform that facilitates online data trading. It gives sellers the capabilities of publishing data, defining the price function, the authorization rules and the data contract. It gives customers the capabilities to search for data services, to query for their price, to invoke them and to pay for the usage. As data are more and more emphasized as a payable asset, the need for data marketplaces rises. There is a lack of marketplace proposals for spatial data. This paper contributes to fill-in this gap. We propose a data model for representing the different types of data involved. The logical representation of data is a quadtree, and the physical representation fits into a key-value store. The model is thus logically simple and extensible, and physically scalable and highly available. We discuss price queries in detail and propose evaluation algorithms.     

合肥市商业地价驱动因素的空间非平稳性分析

基于微观因素的视角,对合肥市商业地价的空间格局、空间异质性进行空间插值和回归分析,研究发现： ① 商业地价空间格局呈现多中心的结构,峰值区集中分布在城市中心,低值区分布在二环线以外的地区;② GWR模型能清晰地反映出各因素对地价影响力的空间差异,容积率、交通站点、CBD和公园是研究区商业地价的关键驱动因素;③ 较之外在因素,内在因素对商业地价的边际作用效率较大,其中尤以容积率最为突出;④ 相较于欠发达地区,容积率在高度发达的区域对地价的正向效应更为显著,而交通站点和CBD对地价的作用正好相反。商业开发更愿意为小型公园支付更高的价格。     

Homeownership and housing consumption change in Urban China: Guangzhou under market transition

ABSTRACT

Homeownership attainment is often seen as the first step in climbing the housing ladder and the building of wealth through acquisition of housing equity. While a number of authors have examined the issue of homeownership switch in China under market transition, the present paper is probably the first study on the extent of housing improvement in conjunction with and after the attainment of homeownership. Based on a household survey conducted in 2010, the study shows that ownership attainment in Guangzhou is generally accompanied by marked housing improvements, and subsequent moves bring further but percentage-wise much smaller improvements. While institution-related factors such as nature of work unit and occupational status might continue to be important, their effects on housing improvements are likely to be felt mainly through the income variable. But hukou status remains significant. More specifically, former peasants on the urban–rural fringe with claim to landownership rights have benefited most from the market-oriented land and housing reform.     

The economic value of streets: mix-scale spatio-functional interaction and housing price patterns

Location factors are vital elements for describing housing price variation. However, limited studies have explicitly illustrated the relationship between urban design and the heterogeneity of housing price patterns. This article specifically evaluates how the interactions between the spatial layouts and land-use system at various scales through street network affect the valuation of the residential properties and the segmentation of housing markets in a network-based Mixed-scale Hedonic Model (MHM) where the submarkets pattern are determined and annotated by the spatially varying estimates on streets. The application of the delivered method in the case of Shanghai City, China, confirms the necessity of using the non-Euclidean distance metric and represent the coexistence between the stationarity and the non-stationarity of the introduced street accessibility variables. The results provide evidence that the impacts of street accessibility measures on the local levels showcase significant spatial variation. It is common for all the places that the properties located on the streets with the higher levels of angular closeness, smaller values of angular betweenness and longer angular distance to the nearby land-uses at the larger scales will be bided higher. It is proven that our delineation of submarket performs better in prediction accuracy than the traditional submarket specifications. The detected submarkets pattern yields that reachable land-use diversity at the pedestrian level is not a preferred factor in the housing submarkets located in the developed city centres. The signs of the price effects of the angular distance to local land-uses distinguish the developing submarkets as two main groups with different degrees of geometrical walkability. It is suggestive that continuously developing pedestrian-oriented neighbours in the walkable areas could contribute to decelerating the growth of house price in Chinese cities. The productions of this study can enrich the understanding of the socioeconomic effects of urban design with greater spatial precision across submarkets.     

Estimating flow resistance in steep slope rills

Recent research recognized that the slope of 18% can be used to distinguish between the ‘gentle slope’ case and that of ‘steep slope’ for the detected differences in hydraulic variables (flow depth, velocity, Reynolds number, Froude number) and those representatives of sediment transport (flow transport capacity, actual sediment load). In this paper, using previous measurements carried out in mobile bed rills and flume experiments characterized by steep slopes (i.e., slope greater than or equal to 18%), a theoretical rill flow resistance equation to estimate the Darcy-Weisbach friction factor is tested. The main aim is to deduce a relationship between the velocity profile parameter Γ, the channel slope, the Reynolds number, the Froude number and the textural classes using a data base characterized by a wide range of hydraulic conditions, plot or flume slope (18%–84%) and textural classes (clay ranging from 3% to 71%). The obtained relationship is also tested using 47 experimental runs carried out in the present investigation with mobile bed rills incised in a 18%—sloping plot with a clay loam soil and literature data. The analysis demonstrated that: (1) the soil texture affects the estimate of the Γ parameter and the theoretical flow resistance law (Equation 25), (2) the proposed Equation (25) fits well the independent measurements of the testing data base, (3) the estimate of the Darcy-Weisbach friction factor is affected by the soil particle detachability and transportability and (4) the Darcy-Weisbach friction factor is linearly related to the rill slope.     

浅谈测绘项目招标工作中评标方法择取

根据招投标相关法律法规在测绘项目招投标工作中的实施,结合多年工作经验,介绍测绘项目招投标工作中的三种不同评标方法,讨论评标方法的择取。     

地面序列影像的高陡边坡高精度三维建模方法

本文针对高陡边坡地形特点,介绍一种基于普通数码相机的多基线地面摄影测量方法,重点研究了普通数码相机的量测化方法和高陡边坡序列数码影像的匹配方法。通过对普通数码相机的量测化,提高了高陡边坡地区数据采集的效率,降低了作业对影像控制和算法的要求;采用种子点与多重约束相结合的多基线匹配方式,解决了高陡边坡序列数码影像匹配中存在的遮挡多、左右片变形大、比例尺不一致等匹配难题。上述建模过程快速且能获得很高精度,实验表明三维建模的相对精度达1/8000~1/12000。     

Urban residential land value analysis: Case Danyang,China

The research attempts to find out how the location of the CBD(central business district), the distance to the main roads, the distribution of the public facilities, and the urban land-use pattern influence the urban residential land value variations. The study begins by identifying the influences into two categories: general circumstance and micro/neighboring circumstances. Benchmark price and market land value are tested to be the results influenced by general circumstance and both the influential range and the influential force of individual land-use are investigated and compared. At last explicit case comparisons are also taken for testing the result. The finding of the research is not only useful for understanding the spatial patterns of land values, but also beneficial for the policy-makers concerning land administration and urban planning.     

人工神经网络的基准地价评估方法研究

探讨了人工神经网络应用于基准地价评估的可行性 ,针对基准地价评估提出了相应的人工神经网络模型和算法改进措施 ,以及在采用神经网络的前提下 ,进行土地定级与基准地价评估的新思路。实例表明 ,人工神经网络方法具有客观、准确、通用等优点。