Prediction of the concentration of chlorophyll-α for Liuhai urban lakes in Beijing City

The weekly water quality monitor data of Liuhai lakes between April 2003 and November 2004 in Beijing City were used as an example to build an artificial neural networks （ANN） model and a multi-varieties regression model respectively for predicting the fresh water algae bloom. The different predicted abilities of the two methods in Liuhai lakes were compared. A principle analysis method was first used to select the input variables of the models to avoid the phenomenon of collinearity in the data. The results showed that the input variables for the artificial neural networks were T, TP, transparency（SD）, DO, chlorophyll-a （Chl-a）,pH and the output variable was Chl-a. A three layer Levenberg-Marguardt feed forward leaming algorithm in ANN was used to model the eutrophication process of Liuhai lakes. 20 nodes in hidden layer and 1 node of output for the ANN model had been optimized by trial and error method. A sensitivity analysis of the input variables was performed to evaluate their relative significance in determining the predicted values. The correlation coefficient between predicted value and observed value in all data and in test data were 0.717 and 0.816 respectively in the artificial neural networks. The stepwise regression method was used to simulate the linear relation between Chl-a and temperature, of which the correlation coefficient was 0.213. By comparing the results of the two models, it was found that neural network models were able to simulate non-linear behavior in the water eutrophication process of Liuhai lakes reasonably and could successfully estimate some extreme values from calibration and test data sets.

Calculation of Water Pollution Control Performance Index:A Case Study of Beijing City

To explore water pollution control level in Beijing,performance evaluation index system of water pollution control in Beijing was constructed based on DPSR framework.Taking driving force,pressure,state and response as primary indexes,25 secondary indexes were established.The combined weighting of the index system was conducted by entropy weight method,coefficient of variation method and CRITIC method.The performance index of water pollution control in Beijing from 2010 to 2018 was calculated,and its dynamic change trend was analyzed.The results showed that the performance index of water pollution control in Beijing was low from 2010 to 2014,but increased year by year from 2015 to 2018,with a good trend.

Study on Government Performance Evaluation and Optimal Countermeasures of Sewage Treatment in Beijing City

In this paper,from the three dimensions of development quality,sustainable development and public satisfaction,the index system of government performance evaluation of wastewater treatment in Beijing City was constructed by conversion of critical success factor method.Using comprehensive evaluation method based on entropy weight method and principal component analysis method,the sewage treatment effect of Beijing municipal government from 2010 to 2017 was quantified,and the government s sewage treatment work was comprehensively evaluated.The evaluation results showed that the government has achieved remarkable results in sewage treatment,but it should continue to optimize the countermeasures in promoting the transformation and upgrading of economic structure,strengthening the management of urban sewage treatment and strict management system of water environment.

Study on the Current Situation and Countermeasures of Rural Domestic Sewage Treatment in Beijing City

In recent years,the construction of rural sewage treatment in Beijing City has developed rapidly,but there are still many problems in some rural domestic sewage treatment. In this paper,the current situation of rural domestic sewage in Beijing City is combed,and its characteristics are summarized. Meanwhile,the current situation of rural domestic sewage treatment in Zhejiang Province,Hunan Province and Shandong Province is summarized by consulting relevant data. By comparing with current situation of rural domestic sewage treatment in Beijing City,it is found that there are some problems in the treatment of rural domestic sewage in Beijing City,such as unsuitable treatment mode,unreasonable discharge requirements and inadequate treatment technology. Therefore,some countermeasures and suggestions are proposed,such as strengthening the investigation,research and planning,and differential formulation of the sewage treatment discharge standards,and establishing modular treatment technology system. It is hoped that this paper will be helpful to the treatment of rural domestic sewage in Beijing City.

A Great Across-the-Century Planning to Build Modernized Capital——The Revision of Beijing City Overall Plan

The revision work of the overall plan from 1991 to1992 under the auspices of the Beijing Institute of Planning and Design(BIPD) has been completed in an all-round way.This article sums upthose background conditions,guiding ideology and basic objectives con-cerned,and the four focal points of the revision.

Effectiveness of groundwater extraction in Beijing since the ingauration of the first phase of the South-to-North Water Diversion Project, China

This study assess the effectiveness of groundwater pressure extraction in Beijing since the opening of the first phase of the South-to-North Water Diversion Project,using survey and evaluation methods.Firstly,an analysis of water consumption structure and the usage of diverted river water in Beijing in recent years was conducted.Secondly,the volume of groundwater pressure extraction in Beijing after the 33 project's inauguration was examined,revealing a decrease from 1.96 billion m^(3) in 2014 to 1.35 billion m^(3) in 2020.The proportion of water supply reduced from 52.3%in 2014 to 33.3%in 2020,leading to an optimized water supply structure.By the end of 2020,groundwater pressure extraction in Beijing is estimated at 446 million m3,with a substantial reduction in over-exploitation of groundwater.Groundwater resources have been effectively replenished,and the strategic reserve capacity has been enhanced.Furthermore,this study evaluates the change in groundwater levels as an indicator of the effectiveness of pressure extraction.The declining trend of groundwater levels in Beijing has been effectively mitigated,and there has been a consistent rebound in groundwater levels over the past five years.

Distribution and Source Apportionment of Polycyclic Aromatic Hydrocarbons from Atmospheric Particulate Matter PM2.5 in Beijing

A total of 11 PM2.5 samples were collected from October 2003 to October 2004 at 8 sampling sites in Beijing city. The PM2.5 concentrations are all above the PM2.5 pollution standard （65 μg m^-3） established by Environmental Protection Agency, USA （USEPA） in 1997 except for the Ming Tombs site. PM2.5 concentrations in winter are much higher than in summer. The 16 Polycyclic aromatic hydrocarbons （PAHs） listed as priority pollutants by USEPA in PM2.5 were completely identified and quantified by high performance liquid chromatography （HPLC） with variable wavelength detector （VWD） and fluorescence detector （FLD） employed. The PM2.5 concentrations indicate that the pollution situation is still serious in Beijing. The sum of 16 PAHs concentrations ranged from 22.17 to 5366 ng m^-3. The concentrations of the heavier molecular weight PAHs have a different pollution trend from the lower PAHs. Seasonal variations were mainly attributed to the difference in coal combustion emission and meteorological conditions. The source apportionment analysis suggests that PAHs from PM2.5 in Beijing city mainly come from coal combustion and vehicle exhaust emission. New measures about restricting coal combustion and vehicle exhaust must be established as soon as possible to improve the air pollution situation in Beijing city.

Beijing Marriott Hotel City Wall

Opened on August 4,2008,four days before the Olympics,the grand and majestic Beijing Marriott City Wall is the largest Marriott hotel outside the United States.

老城区是否满足当代女性的需求?北京老城建成环境的女性友好性研究

Women-friendliness is an important content of inclusive city,while it has received rare attention during the regeneration of old cities.This study constructed women-friendliness indicators in three dimensions,i.e.,security,equity,and specialization,and combined the quantitative calculations of coupling coordination with the qualitative analysis of in-depth interview.25 subdistricts in old Beijing city were selected as case studies to analyze the spatial variation pattern of women-friendliness at the subdistrict level,and the characteristics of supply and demand relationships in three scenarios,namely“living,”“working,”and“traveling,”were summarized.It was found that the spatial variation in terms of women’s security and equity indicators among each subdistrict of the old Beijing city was large,while specialized facilities,which are still at an early development stage,were more evenly distributed but fewer in number.And the facilities in old Beijing city were more inclusive for both female residents and female tourists,while less inclusive for female employees.Finally,specific suggestions for the women-friendly development of old Beijing city were proposed in perspectives of mixed use of function,facility optimization,supply and demand adjustment,etc.,hoping to provide references for other cities to increase inclusiveness in the process of urban regeneration.

街道网络视角下北京旧城商业中心的演变过程和作用机制（英文）

The synergistic relationship between urban functions and street networks has al- ways been a focus in the field of urban research and practice. From the perspective of street networks, by adopting space syntax, this study analyzed the deep structural characteristics and potential evolution rules of commercial blocks attached to street networks in different periods, as well as the corresponding economic, political, and cultural characteristics of an- cient Beijing city over the past 800 years. By combining these with changes in the street network, we further explained the function mechanism of layout and level adjustment in commercial blocks, and the influence of the street network on commercial blocks in the process of historical change. The main conclusions included the following： （1） The urban centripetal-centrifugal siphon effect： the layout form, topological structure, and traffic mode changes in the street network had corresponding guidance for the layout and hierarchical system of commercial blocks, while the centripetal development of the street network could guide the agglomeration effect of commercial blocks, although centrifugal development caused commercial blocks to display outward evacuation. （2） Stage transformation from mu- tation node to smooth development： the layout of commercial blocks came to depend on the ability to cross the commuting flow center, which originally relied on the accessibility of transportation nodes as local centers. Changes in traffic modes mainly affected the adjust- ment of the first-level commercial blocks, which easily led to overall layout mutation. Traffic levels have an obvious positive hierarchical relation with the second- and third-level com- mercial blocks. （3） The adaptation of traditional commercial blocks to the needs of a modern city： affected by the different emerging times and unevenness of the original commercial foundation, commercial blocks have formed various developmental models that meet the needs of modernization, and reach a balance between cultural continuity and functional ad- aptation.

A Retrospect and Prospect of Urban Models: Reflections after Interviewing Michael Batty

Based on an interview with Prof. Michael Batty, a leading scholar in urban modeling, this paper reviews the history of urban models, comments on their present developments and pictures their prospects. The first section briefly overviews the family tree of urban models and then looks further into the causes for their failure in planning application in the first upsurge of related research in the 1960 s and 1970 s. The second section summarizes the current development of urban models, which can be counted as the second upsurge of related research. It is estimated that more research attention will be paid to building dynamic, disaggregate, micro and problem-oriented models, with a combination of top-down and bottomup modeling methods. This can be more capable of tackling the growing urban complexity and uncertainty. Meanwhile, the "big data era" also poses more opportunities for the development of urban models. The last section introduces three new trends in the theoretical, educational and research development of urban models, which compose the idea of "new science of cities" from Michael Batty, the start-up of quantitative urban research education and the establishment of Beijing City Lab.