Typical Chinese Cities Research Articles

Effects of Different Precious Metal Loads of CDPF on Characteristics of VOCs Emissions from a Diesel Bus

Based on heavy chassis dynamometers, an experimental study was conducted in a diesel bus with proton transfer reaction mass spectrometry (PTR-MS). It investigated the effects of volatile organic compound (VOC) emission characteristics with three different diesel oxidation catalyst (DOC)+catalyzed diesel particulate filter (CDPF) after-treatments for a typical Chinese city bus driving cycle (CCBC). The results reveal that the major compounds from the diesel bus are OVOCs, aromatic hydrocarbons, alkenes, alkanes, nitrogenous organic compounds, and polycyclic aromatic hydrocarbons (PAH), and that the OVOCs account for more than 50%of the total VOCs. With the same precious metal composition and ratio of the proportion in the CDPF catalyst, the emissions of VOCs decrease with an increase in precious metal load. The emission reduction rates of the VOCs are 36.2%, 40.1%, and 41.4%, respectively, when the precious metal loads are 15 g·ft-3 (type A after-treatment device), 25 g·ft-3 (type B), and 35 g·ft-3 (type C). The average emission rates of alkanes for the three kinds of DOC+CDPF after-treatments are all over 59% for the entire CCBC cycle. The type C after-treatment device can reduce the alkane emissions by 70.2%, with a slight advantage for the OVOC reduction compared with type A and type B devices. For unsaturated hydrocarbons, including aromatic hydrocarbons, alkenes, and PAHs, the after-treatment devices have a catalytic effect, but there is no significant difference between them. The emissions of nitrogenous organic compounds are greatly decreased, by 50.5%, with the type A after-treatment, but the reduction rate decreases with an increase in precious metal load. In addition, OVOCs, aromatic hydrocarbons, and alkenes are the most important contributors to ozone formation. The adoption of DOC+CDPF reduces the emissions of VOCs and, therefore, the ozone formation potential. Taking into account the emission reduction rates and costs of the three different after-treatments and for weighting coefficients of 0.8 and 0.2, respectively, the type B after-treatment is the optimal solution.

Study on emission characteristics of hybrid buses under driving cycles in a typical Chinese city

In this study, a hybrid city bus was taken as the research object, and through a vehicle drum test, the hybrid bus emissions, the transient gas pollutant emissions, and the particle size and number...

Concentration, source identification, and exposure risk assessment of PM2.5-bound parent PAHs and nitro-PAHs in atmosphere from typical Chinese cities

Sixteen parent PAHs and twelve nitro-PAHs were measured in PM2.5 samples collected over one year (2013–2014) at nine urban sites in China. During the sampling period, concentrations of individual nitro-PAHs were one or two orders of magnitude lower than their parent PAHs. Typical seasonal variations in parent PAH concentrations, which increased 10- to 80- fold in winter compared to summer, were observed in this study. Conversely, the mean atmospheric concentrations of nitro-PAHs were similar in all four seasons, with the exception of 9-nitroanthracene (9n-Ant). Compared to other nitro-PAHs which were secondary formation products, 9n-Ant had a higher concentration and made up a larger proportion of total nitro-PAHs. Positive matrix factorization results indicated that 9n-Ant sources included biomass burning (20%), vehicle exhaust emissions (43%), and secondary formation (30%). Overall, the elevated concentrations of parent PAHs observed in winter correlated with the contribution from coal combustion at all sites, especially in north China (>80%). The contribution of secondary formation products to total nitro-PAHs was measured during the summer, and was especially high in the larger cities such as Shanghai (84%), Beijing (76%), Guangzhou (60%), and Chengdu (64%), largely due to the summer concentrations of parent PAHs were markedly lower than in winter.

Study on emission characteristics of hybrid bus under driving cycles in typical Chinese city

In this study, hybrid city bus was taken as the research object, through the vehicle drum test, the vehicle emissions of hybrid bus, the transient emissions of gas pollutants, as well as the particle size and number distribution were surveyed. The results of the studies are listed as follows: First, compared to traditional fuel bus, hybrid bus could reduce about 44% of the NOx emissions, 33% of the total hydrocarbon emissions, and 51% of the particles emissions. Furthermore, the distribution of particles number concentration of test vehicle became high in middle and low in both sides. More specifically, the particle number concentration was mainly concentrated in the range from 0.021 to 0.755μm, the maximum was 0.2μm, and particle size of particulate matter (PM) less than 1.2μm accounted for 95% of the total number concentration. Particulate mass concentration was increased with increment of particle size, and the maximum of particulate mass (PM) concentration was 6.2μm. On average, whether traditional fuel bus or hybrid bus, the particle size of particulate matter(PM) less than 2.5μm accounted for more than 98% in the particles emission. It is found that the particles are more likely to deposit to the lung, respiratory bronchioles and alveoli, causing respiratory and lung diseases. Therefore, how to control the PM emissions of hybrid bus is the key factor of the study.

Urban transport carbon dioxide (CO2) emissions by commuters in rapidly developing Cities: The comparative study of Beijing and Xi’an in China

To understand the changing relationships between commuting CO2 emissions (CCE), travel behavior and urban forms, this paper provides a comparative study between the typical Chinese cities of Beijing (more developed) and Xi’an (rapidly developing). Further, the effects of metro services on reducing CCE were explored, and comparative analysis on CCE between the inner sprawling suburbs and outer suburbs was conducted. It was found that: (i) the increases in CCE are several times larger than the increases in urban size, population, and economic developments; (ii) metro services reducing CCE near metro stations is not statistically significant, maybe because the proportions of car users near the metro stations are similar to the two cities’ average levels, which is caused by their higher household income and the longer travel time using the metro; (iii) in Beijing, there are smallest CCE in the outer suburbs due to job-housing balances, short distance and large percentage of non-motorized mode uses while largest CCE in the inner sprawl suburbs due to car trips with long distance. These findings indicate that to cope with the rapidly increasing CCE, more attention should be paid to developing strong industry and real-estate simultaneously; the improvement in the feeder bus and public bicycle systems should also be reinforced to reduce the total travel time of metro users; and satellite cities with job-housing balance are greatly needed. The implications will benefit efforts to reduce CCE and mitigate global climate change, and they also provide empirical evidence and reference values for other global cities.

State Owned Enterprises in China's Housing Boom: A Case Study of Chengdu, Sichuan

China’s property market has been the subject of much media coverage in recent years. Rapid price increases for residential property and the possibility of a price bubble in many cities has led the central government to take a myriad of regulatory measures to cool housing markets. Scholarly attention has focused either on inter-city analyses or case studies of the high-GDP coastal cities like Shanghai and Beijing, and too little is known about the property market dynamics of more typical Chinese cities. Moreover, there is a dearth of research on the role of State Owned Enterprises (SOE), which play an important role in China’s housing boom. This paper uses a comprehensive set of georeferenced housing transactions, joined with remote sensing data and data on neighborhood amenities and transportation infrastructure, to analyze the dynamics of the Chengdu housing market from 2004 to 2011 and assess the differences between housing produced by SOE and other types of developers. The observed reduction in variation in housing prices and sizes, as well as a growing premium for larger units can be plausibly connected to new government regulations. We find that units developed by SOE sell at a discount.

Performance analysis of a tower solar collector‐aided coal‐fired power generation system

AbstractIn this paper, a tower solar collector‐aided coal‐fired power generation (TSCACPG) system is proposed and studied in order to save the fossil energy and protect the environment. The integration scheme of tower solar collector and conventional coal‐fired power plant is proposed. Based on the simulation platform TRNSYS, the TSCACPG system model is established and the dynamic performance of the TSCACPG system with the operating mode of coal saving is studied. The TSCACPG system performances of 1 day and 1 year are all discussed by using the DNI data of typical year in Chinese typical city of Dunhuang. Then, the sensitivity analysis of the TSCACPG system is carried out by changing the heliostat field scale (the size of the molten salt tower also changes accordingly). The annual performance of the TSCACPG system is also acquired. In consideration of the economic costs, the heliostat field area with the maximum annual solar‐to‐electric efficiency is selected as the optimal value. The results show that, for the case studied, the optimal heliostat field area is 101,400 m2, and the maximum annual solar‐to‐electric efficiency is 16.74%. And under the optimal situation, the standard coal consumption rate of the original coal‐fired power plant is reduced from 301.5 g/kWh to 294.5 g/kWh.

Urban expansion in China and its effect on cultivated land before and after initiating “Reform and Open Policy”

Urbanization in China has expanded at an unprecedented speed since the declaration of “Reform and Open Policy” and presented many challenges. Unbalanced regional development, appearance of super megacities and concomitant problems, and conflicts between urbanization and cultivated land protection are three critical problems that Chinese urbanization has to face. To develop new plans for foreseeable future urbanization in China, it is critical to understand the evolving history of cities across China. This study maps urban expansion of 60 typical Chinese cities based on large amount of remote sensing data and the labor-intensive image interpretation method, in order to understand the history of urban expansion from the 1970s to 2013. Results showed that area of cities expanded 5.23 times compared to their area in the 1970s. Urban expansion in China accelerated three times (1988–1996, 1999–2006, and 2009–2011) and decelerated three times (1997–1998, 2007–2008, and 2012–2013) over the 40 years. The urban area of South China expanded most significantly 9.42 times, while the urban area in Northeast China expanded only 2.37 times. The disparity among different administrative ranks of cities was even greater than (3.81 times) the differences among different regions. Super megacities have been continuously expanding at a fast rate (8.60-fold), and have not shown obvious signs of slowing down. The proportion of cultivated land among the land sources for urban expansion decreased to a small extent in the 1990s, but cultivated land continues to be the major land source for urban expansion. Effective future urbanization needs controlling the expansion scale of large cities and reasonably developing medium and small cities, as well as balancing regional development.

The interaction between land subsidence and urban development in China

Abstract. The Yangtze River Delta and North China Plain are experiencing serious land subsidence development and are also the areas that have undergone the fastest urbanization. Rapid urban development inevitably requires more water resources. However, China is a country with small per capita water resources, nonuniform distribution of water resources, and over-exploitation of groundwater – all of which are critical factors contributing to the potential for a land subsidence disaster. In addition, land subsidence has brought about elevation loss, damaged buildings, decreased safety of rail transit projects, lowered land value, and other huge economic losses and potential safety hazards in China. In this paper, Beijing, a typical northern Chinese city deficient in water, is taken as an example to explore (a) the problems of urban development, utilization of water resources, and land subsidence development; (b) the harm and influence of land subsidence hazards on urban construction; and (c) the relationship between urban development and land subsidence. Based on the results, the author has predicted the trend of urban development and land subsidence in Beijing and puts forward her viewpoints and suggestions.

Performance analyses of building energy on phase transition processes of VO2 windows with an improved model

A new model is established to obtain the building energy with a gradual change process of VO2 optical properties. Based on this method, three types of existing VO2 films are employed to simulate the heating and cooling energy consumptions in five typical Chinese cities. The results show that the smart characteristic is not evident in VO2 glasses because these films are almost in the cold state or cold transition state in the entire year. To improve this situation, the concept of an ideal thermochromic intelligent glass is put forward. Unexpectedly, the level of energy consumption increases with the film phase transition temperature decreasing in the heating period. However, the energy-saving effects will be effectivelyimproved both in the cooling and heating periods when the phase transition process interval is shortened. The cooling energy consumptions for the ideal glass decrease by at most 81.7% and 70.5% compared with white glass and Low-E glass, respectively. In the heating period, the level of energy consumption for the ideal glass is better than Low-E glass.

Methodology for Optimal Sizing of Hybrid Power System Usingparticle Swarm Optimization and Dynamic Programming

Abstract A methodology for optimal sizing of hybrid battery-ultracapacitor power system (HPS) is presented. The purpose of the proposed methodology is to locate the optimal voltage levelfor HPS used in a plug-in hybrid electric vehicle (PHEV). A combined optimization framework for a HPS is proposed and the optimization problem is solved in a bi-level manner. The framework contains two nested optimization loops. The outer loop evaluates the selected parameters throughparticle swarm optimization (PSO) algorithm, while the inner loop generates the optimal control strategy and calculates the costs through dynamic programming (DP) algorithm. The Chinese Typical City Bus Drive Cycle (CTCBDC) has beenused to verify and evaluate the performance of the proposed methodology. The optimization result shows that higher voltage degree usually means better performance and the battery tends to provide a constant power for the HPS. It is noted that the constant powercloses to the high efficiency district of the battery and DC/DC convertor. After that the optimal result is further analyzed undervarious optimization goals andbattery charge/discharge current constrains.

An application of system dynamics for evaluating planning alternatives to guide a green industrial transformation in a resource-based city

A number of resource-based cities have suffered from unsustainable industrial pathways and aggravated environmental devastation. For such types of cities, especially in developing countries, it is imperative to launch a green industrial transformation that calls for considering more alternatives that involve environmental concerns in the planning process. This study aims to develop a system dynamics model for evaluating different planning alternatives concerning three prominent factors: industrial scale, structure, and efficiency; the findings are expected to assist decision-makers with a wider perspective in retrofitting the industrial system. Linfen, a typical Chinese resource-based city, is taken as a case. The results showed that compared with structure adjustment and technical progress, scale control should be taken as the foremost transformation measure for some cities with more excessive industrial capacities or in even worse environmental situations. For Linfen, the production capacities of its four main industries, i.e., coking, iron making, steel making and coal-power generation, need to be cut down, respectively, by 18.0%, 8.6%, 12.7% and 64.2% compared to the local industrial department's preferred options. Because of its capability to depict sophisticated interactions of environmental issues and industrial factors under diversified circumstances, alternative evaluation with the SD model is of great potential for delivering more integrated knowledge to decision-makers in industrial planning towards green transformation.

Development of a driving cycle for city bus in Harbin of China

The bus line types of Harbin are regular, bus rapid transit (BRT) and suburban. The actual driving data is collected by GPS devices and divided into kinematics sequences. Eleven characteristic parameters of the kinematics sequences are calculated. The representative driving cycles are constructed by principal component analysis and cluster analysis. The Harbin driving cycle is compared with the common driving cycles of Zhuzhou city and Chinese typical city. The energy consumption simulations of an electric vehicle model are conducted through MATLAB with different common driving cycles. The simulation results show the difference between Harbin driving cycles and common driving cycles and verify the construction significance of Harbin driving cycles.

Factors that influence soundscapes in historical areas

This study is designed to reveal the soundscape characteristics of historical areas of Harbin, China, a typical Chinese city with fast urbanization process, through an intensive questionnaire survey and acoustic measurements. It was found that major sound sources vary considerably in different areas, with business-based historical areas featured by cries from street vendors, leisure-based and tourism-based historical areas by music, and residential historical areas by traffic noise. The average equivalent sound pressure level is between 62 and 70 dBA, and 53.6% of the interviewees are satisfied with the soundscape while 15.1% are not. With a given sound level, the interviewees have different levels of acoustic satisfaction at different sites featured by different sound sources. The acoustic satisfaction is, to a large extent, correlated with the subjective evaluation of temperature, humidity, wind environment as well as cultural identity, vitality, public sanitation, landscaping and green areas. Moreover, the interviewees' age, occupation, duration and purpose have significant effect on their acoustic satisfaction.

Control Strategy of the Dual Motors Coupling Propulsion for Battery Electric Buses

A novel drive system the Dual Motors Coupling Propulsion (DMCP) for battery electric buses was proposed, and its structure and working principle were introduced. For the power and comfort performance of the vehicle, the control method of the motors and the coordinated control strategy of the DMCP were developed. The co-simulation platform of AMESim and Simulink was established, based on which the dynamic model of the vehicle equipped the DMCP was built. The simulation results show that the DMCP runs smoothly in the Chinese typical city bus driving schedule. This indicates that the control strategy can manipulate the DMCP to drive the bus powerfully and smoothly. This has laid the foundation of the further research of the DMCP.

Climate change and corrosion damage risks for reinforced concrete infrastructure in China

A changing climate which leads to increases in atmospheric CO2 concentration, and changes in temperature and relative humidity (RH), especially in the longer term, will accelerate the deterioration processes and consequently decline the safety, serviceability and durability of reinforced concrete (RC) infrastructure. This paper presents an investigation of carbonation-induced deterioration in three typical Chinese cities (Kunming, Xiamen and Jinan) under a changing climate. The changing trends of atmospheric CO2, local temperature and RH of typical Chinese cities are projected based on the latest CO2 emission scenarios. The time-dependent analysis is based on Monte Carlo simulation, and includes the uncertainty of climate projections, deterioration processes, material properties, dimensions and accuracy of predictive models. Deterioration of RC structures is represented by the probabilities of reinforcement corrosion initiation and damage. It was found that the mean carbonation depths by 2100 may increase by up to 45% for RC structures in China due to a changing climate. It was also found that climate change can cause an additional 7–20% of carbonation-induced damage by 2100 for RC buildings in temperate or cold climate areas in China. The findings provide a basis for the development of climate adaptation strategies through the improved design of concrete structures.

Combining Online News Articles and Web Search to Predict the Fluctuation of Real Estate Market in Big Data Context

The real estate price is of paramount importance in both economic and social fields. It is a key indicator of the operation of real estate market and its prediction is essential in the decision-making process of both average people and official governments. Past researchers on this topic have already proposed several prediction methods including linear regression models, nonlinear regression models and machine learning models. Nevertheless, those models have generally neglected the impact of human behavior, which we believe is a significant factor of the real estate price prediction. What’s more, past studies have shown that news sentiments could improve the prediction performance of real estate price. Search engine query data were studied to reflect web users’ behavior by analyzing the frequency of words searched by online users. Researchers have already used the news sentiments and query data for prediction, respectively. But none have combined them together as an integrated model. In this paper, we propose an integrated method that throws new light on the prediction of real estate price in China by integrating these two factors into the forecasting model. In our method, we extract sentiment series from both news data and search engine query data by adding weights to original sentiment series that are produced by news data alone. Then both the weighted series and original ones are used as inputs of several well-acknowledged data mining models, including SVR, RBFNN and BPNN, to produce prediction results. To validate the integrated model, we apply it to four representative cities in China respectively, and compare the results produced by the integrated model using weighted inputs with non-integrated ones using original inputs. The results show that for every one of the four cities, the integrated model generally leads to lower prediction errors than the non-integrated ones. This not only validates the model’s accuracy and universality, but also proves the hypothesis that human searching behavior as a strong impact in typical Chinese cities’ real estate market and can enhance the prediction accuracy of real estate prices.

The trend of natural illuminance levels in 14 Chinese cities in the past 50 years

Maximizing natural illuminance, seeking sustainable ecological development, and saving electricity are very important. The annual total natural light illuminance values of 14 typical Chinese cities in different climate regions were obtained in this study based on solar irradiance data of the cities in the past 50 years (from 1961 to 2010). A luminous efficacy model was integrated in the analysis of data. This study analyzes the overall and inter-annual change trends of total natural light illuminance values in each city. Mann-Kendall test method or nonparametric test method can reveal the changing trend of time series; the method does not require samples to follow a specific distribution and cannot be affected by a few abnormal values. The method is suitable for data with abnormal distribution. In this paper we analyze the trend of natural illuminance levels in 14 Chinese cities by Mann-Kendall trend analysis and Mann-Kendall mutation test. The results show that the overall change trends in the annual total natural light illuminance values in Beijing, Guangzhou, Urumchi, Xian, Xining, Shanghai, Changsha, and Chongqing are extremely obvious; the change trend in Erenhot and Kunming are obvious; and those in Changchun, Yushu, Heihe, and Fuzhou exhibit no change. The inter-annual change trends in the total city illuminance values in Chongqing and Urumchi decreased gradually year by year; those in Beijing, Shanghai, Changsha, Guangzhou, Erenhot, Xian, Xining, and Heihe increased at first and decreased in the later years. The illuminance values in Changchun and Yushu increased initially, decreased, and then increased again; in Kunming, these values decreased initially, increased, and then decreased again. The annual total illuminance values of natural light in some cities significantly decrease, thus affecting the accuracy of architectural daylighting design. The total change trend of natural light illuminance has an insignificant association with Chinese light-climate regions. Many factors influence natural illuminance: the major factors are cloud cover and aerosols from air pollution; the minor factors are water vapor, atmospheric molecular scattering and absorption, and solar activity.

Energy Efficiency and Fuel Economy Analysis of a Series Hybrid Electric Bus in Different Chinese City Driving Cycles

Based on analysis of the configuration and powertrain parameters of the series hybrid electric bus typically operating in certain Chinese city, this paper establishes simulation model of the series hybrid powertrain. The energy efficiency and fuel economy of the series hybrid electric bus are analyzed by energy flow method in the driving cycles of Chinese typical city, Zhuzhou city in Hunan province of China, and Hefei city in Anhui province of China. Simulation results show that, APU parts selection, braking system configuration and control of the series hybrid electric bus can be optimized. The fuel-saving ratios reach nearly 20% in all driving cycles.

Evaluation of excess mortality caused by PM2.5 in four typical Chinese big cities

To evaluate the adverse effects of particulate matter ≤ 2.5 µm in aerodynamic diameter (PM2.5) on public health in four typical cities: Beijing, Shanghai, Guangzhou and Xi'an. Daily health and meteorological data (including ambient temperature and relative humidity) were collected in the past several years. For the relative risk of PM2.5 effects on mortalities, generalized additive model (GAM) was used to obtain the exposure-response coefficients between PM2.5 and non-accidental mortalities after controlling time trend, week effects and meteorological factors. Then excess mortalities were calculated according to coefficients, health data and air pollution level. The relative risks of PM2.5 effects on mortalities were 1.0027(1.0010-1.0044), 1.0020 (1.0007-1.0033) , 1.0056 (1.0022-1.0091), 1.0036 (1.0011-1.0061) for Beijing, Xi'an, Shanghai, Guangzhou respectively. Compared with relative risks in northern cities (Beijing and Xi'an), relative risks in southern cities (Shanghai and Guangzhou) were higher. The numbers of excess mortalities caused by PM2.5 in Beijing, Shanghai, Guangzhou, Xi'an were 2349, 2980, 1715, 726 and accounted for 1.9%, 1.6%, 2.2% and 1.6% of the total death number in 2010 respectively. Although relative health risks caused by PM2.5 vary geographically for urban residents, public health is endangered. More efforts should be devoted to reducing PM2.5 pollution.