Due to anthropogenic emission reductions, the mass concentration of fine particulate matter (PM2.5) in China has markedly decreased in recent years. In this study, we selected the Huaihe River Basin (HRB), which is located in the middle of the North-South climatic transition zone of China, to investigate the reasons for the decrease in the PM2.5 concentration. Based on the observed PM2.5 concentration and meteorological data for 2015-2020, the Kolmogorov-Zurbenko (KZ) filter method was employed to decompose the original time series of the PM2.5 concentration. The results demonstrate that the short-term (PM2.5ST), seasonal (PM2.5SN), and long-term (PM2.5LT) components of PM2.5 variations over the HRB accounted for 55.6%, 34.7%, and 4.4% of the total variance, respectively. PM2.5 variations in coastal cities and cities with relatively high latitudes and longitudes were more affected by the short-term component. It was identified that the PM2.5 concentration in the HRB declined at a rate of 2.58-8.12 mu g/m3/year. The meteorological conditions and emission reductions all positively influenced the PM2.5 decrease, which contributed 30.09% and 69.91%, respectively, to the PM2.5LT decrease in the HRB. It is noteworthy that with the PM2.5 decrease, the conversion efficiency of SO2 to sulfate and NO2 to nitrate might be enhanced. The unbalanced emission reductions in SO2 and NO2 are not conducive to the further decline in PM2.5. This study suggests that more efforts should be made to control NO2 emissions in the HRB.

Quantitative evaluation of the uncertainty in spatial topological relations can provide the reliable basis for applications in automatic evaluation of multi-scale topological relation consistency,spatial reasoning,and spatial queries.A geometric measure-based topological distance was defined.A rough set model for uncertainty in topological relation proposed to explore a quantitative method for determining topological distance.Furthermore,this paper presents the measure index for uncertainty in spatial topological relations of multi-scale spatial entities.A case study shows that the model proposed in this paper is reasonable,and suitable for the quantitative evaluation of topological relations found in multi-scale representation processes.

An improved genetic algorithm was proposed to solve the problem of more iterative times and cost more time in traditional genetic algorithm.The algorithm was designed to optimize the task scheduling mainly from two as-pects:the execution time and the cost of the mission.The corresponding fitness function and boundary function were designed by establishing the task scheduling model.The results showed that, in task scheduling using genetic algo-rithm, the average waiting time was shorter and scheduling costs required lower than that of the traditional genetic algo-rithm.

针对Photoshop图像处理课程中存在的课程缺少多样性、开课学时不合理、授课内容与本专业脱节、考核方式单一等问题，提出Photoshop图像处理课程教学改革的方法与思路，以提高教学质量。

In order to improve the purification efficiency of micro-polluted raw water in drinking water plant,polyaluminium Chloride(PAC) was used as coagulants,and the enhanced coagulation were studied using pre-oxidation,activated carbon,coagulant aid and sludge for raw water.The results were as follows:(1) organic matter was broken down into smaller molecular weight,sparse higher hydrophilic organisms by pre-oxidation enhanced coagulation,and the dosages of KMnO4,H2O2 and O3 were 1.5~2,4~6 and 4~6 mg/L,respectively;(2) organic matter with molecular weight in 0.6~3 kD was assorted to improve the removal of CODMn and color by powdered activated carbon enhanced coagulation,and the dosages of powdered activated carbon was 20~30 mg/L;(3) PAM can effectively improve the floc particle size,particle settling velocity to accelerate the CODMn removal efficiency,and the dosages of PAM was 0.2 mg/L;(4) return sludge can provide a condensed core and give full play to the increased role of the adsorption and the volume swept,and the dosages of sludge was 15 mg/L.

In order to resolve the disadvantage that similarity models of space direction relations do not consider the uncertainty of space target,by means of the advantage that rough-set expresses uncertainty problems,rough-set expression method of space direction relations is defined in cone-shaped models of cardinal direction relations.The computation and rough-set expression method of similarity of multi-scale space direction relations based on the positional uncertainty of space target are proposed,this method makes that the value of similarity of multi-scale space direction relations is varied in a interval,which accorded with human cognition of similarity of multi-scale space direction relations.

In the overall land use planning at town level,the symbols in ArcGIS can't satisfy the need,so a special symbol library designed is necessary.The processes and methods were introduced on how to design marker,line and fill symbols using Font Creator 5.6 and the symbol manager of ArcGIS.Then a convenient special symbols library was constructed for the overall land use planning.

本文介绍了一种以可视化开发工具Visual Basic和MapObjects组件为平台的简单高效的电子地图系统的设计和实现方法,开发一个具有特征查找、属性查询、表达式查询等功能的电子地图浏览系统,提供方便、快捷的浏览功能及辅助工具,具有成本低、操作便捷等优点,具有一定的应用价值。

VFAST TCP protocol is researched in detail,its design motivation and algorithm realization are discussed.The round-trip delay estimation problem is emphatically expounded.In NS simulation environment,we conduct the simulation of VFAST and FAST congestion control algorithms,and analyze and summarize the advantages of VFAST TCP performance according to the simulation results.

Assessment of uncertainty for spatial data is an important means to ensure the spatial data quality.Because of the complexity on the multi-scale expression uncertainty for point cluster,the index and model is an essential issue for assessment of multi-scale expression uncertainty on point cluster.Based on the flow of multi-scale expression of point group and spatial analysis,this paper ascertained the assessment content of multi-scale expression uncertainty for point group that includes the uncertainty of position and spatial analysis.The assessment indicator K and the quantitative model of the position uncertainty of point cluster and its multi-scale representation were established.According as the error propagation law,this paper deduced the assessment method of spatial analysis in different scale for point cluster.Finally,the change rule of uncertainty for point cluster in the course of scale-extend and spatial analysis were gained.This study made up for the weakness of existing research,and it also provided theoretical foundation for the quality assessment of geographic point cluster data on multi-scale representation.Meanwhile,it would be the reference standards for quality control and spatial decisions.

A method for urban major road information extraction from QuickBird imagery is proposed.First,the use of histogram equalization for the enhancement of the original remote sensing image processing,outstanding image edge information.With the Otsu automatic thresholding method for image enhancement processing after the initial split,extract urban roads and houses and other buildings.According to the image difference between the morphological characteristics of various elements to build a different tag images with different structural elements to build the road model,with the model of thresholding the image after morphological reconstruction,were extracted from the city roads and buildings.Generated reconstruction of the road shape optimization module,extract the contours of urban roads.Experimental results show that the method can effectively extract images from high resolution remote sensing of urban road network.

查询结果如何组织和存储能够极大的影响查询的效率,从查询结果的缓冲存储方面来进行讨论,并进行实例分析。

The strong and the weak practical capacity of urban and rural planning and resources management student will influent employment rate. Practical capacity of urban and rural planning and resources management student must be strong to society by research. Weak reasons of students’practical capacity are analyzed. Constituting course structure to train practical capacity of student,enhanced the establishment of practice bases and raising teacher specialization are main ways to improve student practical capacity.

FAST TCP是一种针对当前高性能网络的高速、长延迟等特点的TCP拥塞算法.论文首先对传统的TCP Reno进行介绍,讨论其算法与FAST TCP的不同点.然后重点分析FAST TCP体系结构和算法.利用NS2仿真工具测试了传统TCP Reno与FAST TCP在吞吐量方面的性能差异.实验验证了FAST TCP较传统的TCP Reno在吞吐量方面具有很大的性能优势.