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As the basic unit of a city, community is an important carrier of residents' healthy life. With the development of society, the environmental status of old communities has been unable to meet the needs of residents' healthy life, and it is urgent to optimize the community environment. The emergence of novel coronavirus also put forward more strict requirements for the grassroots governance of old communities in China. Taking Fuguoli community in Beijing City as an example, the problems existing in the external environment of old communities were excavated from the perspective of functional requirements, and the distributed green space layout pattern and the dynamic simulation of community microclimate environment was constructed through the method of field survey and numerical simulation. Furthermore, the environmental optimization strategies of old communities with combination of peacetime and epidemic situation were put forward to help the epidemic prevention and control. [ABSTRACT FROM AUTHOR]

Thermal comfort indicates the sensation of humans towards the surrounding environment. This research work proposes a novel method for assessing thermal comfort indices of the Beijing Historical Town Blocks. Motivation. Maintaining a proper thermal comfort is essential for healthy living and promoting the use of low energy strategies; therefore, there is an intense need for research, analysis, and assessment of thermal indices for indoor environments. Objective. The research work intends to present a generalized model for outdoor thermal comfort assessment by investigating thermal comfort evaluation indices of the past ten years through the CiteSpace software and dynamic simulation system. Methodology. Based on a study of 19 streets over 6 blocks in the historical area of Beijing, validity of the four evaluation indices of thermal comfort of the street space is analyzed using real-time data monitoring, questionnaires, regression analysis, and model establishment. Statistical analysis is performed on the basis of the four commonly used thermal comfort evaluation indices along with using universal thermal climate index (UTCI) and the comfort threshold range for evaluation. Findings. Outcomes of the analysis revealed that UTCI thermal neutral value in the historic block was 20.59°C and the comfort range was 16–25°C. It was observed that UTCI indices were inversely related to the street vegetation coverage; therefore, unlike street aspect ratio and building shadow, green planting elements had a significant effect on the thermal comfort of outdoor environment. Implication. As applicability extent of the four indices is fairly broad, the proposed method is adaptable for the assessment of indoor and outdoor environments. Thermal comfort index analysis and evaluation are appropriate for advance research in microclimate environment. Application. The research work suggests improvement strategies of microclimate environment in the historical blocks and, therefore, has significant applications in addressing the challenges of outdoor thermal comfort systems. [ABSTRACT FROM AUTHOR]

In order to design an optimal carbon peak and carbon neutralization pathway for the high-density building sector, a dynamic prediction model is established using system-dynamics coupled building life cycle carbon emission model (SD-BLCA) with consideration of future evolutionary trajectory and time constraints. The model is applied in Beijing using the SD-BLCA combined with scenario analysis and Monte Carlo methods to explore optimal trajectory for its building sector under 30-year timeframe. The results indicate that by increasing the proportion of renewable energy generation by 7% and retrofitting 60 million m2 of existing buildings, these two mature measures can offset the growth of carbon emissions and achieve the peak target by 2025. However, achieving carbon neutrality necessitates a shift from isolated technologies to a comprehensive net-zero emissions strategy. The study proposes a time roadmap that integrates a zero-carbon energy supply system and the carbon reduction measures of the whole life cycle. This strategy primarily relies on renewable sources to provide heat, power, and hydrogen, resulting in estimated reductions of 29.8 Mt, 28.1 Mt, and 0.7 Mt, respectively. Zero energy buildings, green buildings, and renovated buildings can reduce carbon emissions through their own energy-saving measures by 8.4, 18.2, and 11.8 kg/m2, respectively. [Display omitted] • System-dynamics coupled life cycle dynamic prediction model were established. • The major CO 2 emission from building operation stage ranged 52%–73% in megacity. • CO 2 emission reduce 59 and 18 Mt from energy supply and consumption for building neutrality. • Renewable energy includes 51% Heat, 48% Power and 1% hydrogen in building neutrality. • Enhancement of energy efficiency and zero-carbon energy contribute building neutrality. [ABSTRACT FROM AUTHOR]

The constant building drag coefficient was replaced by a mechanical drag coefficient formulation in a multilayer urban canopy system coupled with the Rapid-refresh Multiscale Analysis and Prediction System to improve the wind speed prediction performance in complex urban areas. Although this formulation has been assessed in idealized urban areas by computational fluid dynamic simulations, the applicability of this formulation has not been sufficiently evaluated, especially in complex urban areas with inhomogeneously distributed tall buildings. The main objective of this study is to evaluate the performance of the coupled system in the Beijing urban area. The results show that the average wind speed model performance is improved by 40% in summer and 36% in winter by introducing a drag coefficient into the regional forecast model. [ABSTRACT FROM AUTHOR]

Mine tailings ponds that contain heavy metals are sources of potential risk to human security and ecosystem health. China particularly faces challenge of accidental water pollution risk from more than 8869 mine tailings ponds in serve by 2015, some of which are close to residential areas and other important infrastructures within 1 km downstream. To address watershed-scale risk assessment of accidental water pollution from mine tailings ponds, a Bayesian Network-based Risk Dynamic Simulation (BN-RDS) model was proposed to simulate "sources/stressors-receptors-endpoints" risk routes. An accidental water pollution convection-diffusion simulation was coupled to Bayesian Networks to perform the risk dynamic simulation and risk evolution quantification at watershed-scale. This method was applied to the risk assessment of 23 tailings dams in 12 sub-watersheds covering the Guanting Reservoir basin (the major backup drinking water source for Beijing) in Zhangjiakou City, China. The result indicated that ecosystem health and property security were the endpoints at the highest risk in the overall watershed. Spatially, the combined risk distribution map showed the risk was higher in the downstream of the Guanting Reservoir Watershed and in its two tributary basins (the Qingshui River and the Longyang River). This research highlighted a probabilistic approach to accidental water pollution risk assessment of tailings ponds with verifiable and tangible results for risk managers and stakeholders. • A Bayesian Network-based Risk Dynamic Simulation (BN-RDS) model is developed. • The combined risk distribution of Guanting Reservoir watershed was mapped. • The 2022 Winter Olympics site suffers a minor threat of accidental pollution risk. • BN-RDS model proves to be useful for the incident risk early-warning management. [ABSTRACT FROM AUTHOR]

From the perspectives of "reduction emission" and "congestion releasing", a vehicle pollution reducing management model is established based on the relevant data of 2005-2017 in Beijing. Firstly, the graphical function is constructed by using the approach of integrating system dynamics and grey model theory. It has improved the prediction precision of the parameters and put forward a new method of system dynamics modeling. Secondly, the integrity test (such as qualified verification of the degree of incidence) is used to test the model, in order to overcome some insufficient of the local testing method. Moreover, three kinds (including the low, medium and high policy) of schemes are simulated, and the results show that the low policy has a "double inflection-point effect". In addition, there is a "marginal diminishing effect" between the medium and high policy. Finally, taking the medium policy as an example, mid-long term dynamic simulation is carried out for the major variables (such as CO, HC, NOx, PM, and per vehicle area of roads). In particular, in the short term, the effect of high scheme is quite significant, but from the long-term perspective, the effect will be gradually weakened. Therefore, it can provide decision-making basis for the government. [ABSTRACT FROM AUTHOR]

Abstract The residential building sector consumes a large amount of energy and is recognized as a high potential area where urban energy consumption and carbon emission can be reduced. To reduce the residential energy consumption, relevant policies and measures have been formulated in different places. However, due to the lack of adequate information in the process of policy formulation, the effectiveness of most energy-saving policies for residential buildings seems to be unsatisfactory. Although previous studies have analyzed the energy consumption for a single building or for the whole construction industry at the national level, few of them investigated the life-cycle energy consumption of residential buildings at the city level. Since municipal governments are the key implementers for the reduction of urban energy consumption, a city-level analysis on the energy consumption of residential buildings is highly needed for the policy making. To fill the research gap, this paper develops a life-cycle dynamic simulation model to fully reveal the characteristics of energy consumption of residential buildings at the city level. This easy-to-use model is validated by a case study of Beijing, which demonstrates its applicability and capability to help analyze multiple indicators of residential energy consumption and the dynamic trends of these indicators for municipal governments. Furthermore, the model can be used under the condition of limited input data, and can provide the situation analysis and simulation results of energy consumption of urban residential buildings for facilitating the policy making by municipal governments. Graphical abstract Image 1 Highlights • The proposed model can analyze city-level energy consumption of residential buildings. • The model can be used with relatively limited amounts of input data. • Operation stage accounts for 67% of total residential energy consumption in Beijing. • Heating is the most energy-intensive activity of operation stage in Beijing. • Policy implications for residential energy saving are provided based on the model. [ABSTRACT FROM AUTHOR]

In this paper, three types of green spaces in Xijing Community in Shijingshan District of Beijing were selected for as the measuring points, the HOBO portable weather station was used to monitor the microclimate environmental changes in the same period and summarize the data of microclimate factors. The effectiveness of the simulation was verified by comparing the measured data with the simulated data obtained through ENVI-met. And strategies for microclimate adaptive design in residential areas were proposed according to the microclimate environmental characteristics of several green spaces. [ABSTRACT FROM AUTHOR]

• The paper integrated the flexible wheelset model calculated by the finite element method into the classical vehicle-track coupling dynamic model, and then imported the bearing substructure model into the vehicle-track coupling dynamic model including flexible wheelset to complete the bearing-vehicle-track coupled dynamic simulation model. • In order to solve the contact relationship between raceway and roller, the slice method is used to describe the contact state of bearing substructure, and the contact between inner ring rib and roller is considered. • To verify the correctness of the established bearing-vehicle-track model, field tests were conducted on the high-speed railway line from Beijing to Tianjin. The field tests verify the effectiveness of the simulation model as well as the correctness of the vehicle model under polygonal wheel wear excitation. • The effects of the different orders and amplitudes of wheel-polygonal wear on dynamic performance of the axle-box system are analyzed and discussed in detail. With the increasing speed of high-speed trains and the deteriorating operation environment of axle-box system, the dynamic performance of axle-box bearing directly affects the stability and safety of operation. In this paper, a bearing-vehicle-track coupling dynamic model is established, and its effectiveness is verified by field tests. The simulation results of the coupling dynamic model including wheel-polygonal wear show that the effect of high order polygonal wheel wear (17th ∼ 21st order) on the axle-box system is greater than that of low order wheel wear (1st ∼ 5th order). The frequency domain of axle-box vertical vibration acceleration excited by high order wheel-polygonal wear is mainly distributed in 400 ∼ 600 Hz. The low order polygonal wheel wear amplitude has little effect on the bearing roller-outer raceway contact load. When the wear amplitude of 20th order polygonal wheel is 0.06 mm, the roller-outer raceway contact load is 27.22% higher than that when the wear amplitude is 0.04 mm. In order to avoid bearing failure caused by excessive bearing roller-raceway contact force, the amplitude of 20th order polygonal wheel wear should reduce to less than 0.04 mm. [ABSTRACT FROM AUTHOR]

• This study developed a dynamic copula-based simulation model (DCSM) to single-site seasonal rainfall generation. • The climate-related nonstationarity-based bivariate conditional model would help to predict rainfall for the next season. • Consideration of the nonstationarity would improve the performance of simulation accuracy. In recent years, anthropogenic and climate changes have greatly impacted the probabilistic behavior of hydrometeorological variables, and have challenged the stationarity assumption of marginal distributions of individual characteristics of variables as well as their temporal dependence structure inherent in copula-based modelling. This study developed a dynamic copula-based simulation model (DCSM) for single-site seasonal rainfall generation, observed at Beijing Station in Haihe River basin, China. The model entailed four phases: (1) nonstationary modelling of the margins by the Generalized Additive Models for Location, Scale and Shape (GAMLSS); (2) dynamical copula method to describe the nonstationary temporal dependence structure of rainfall observed at adjacent two seasons; (3) a dynamic copula-based conditional quantile function to generate simulated series; (4) performance assessment of the simulated series by the proposed DCSM model with the preservation of basic statistics of each sequence and simulation accuracy at each data point. Comparison of the nonstationary and stationary models to simulate the seasonal rainfall series shows that the incorporation of nonstationarity in hydrometeorological simulation would improve the performance of simulation accuracy. [ABSTRACT FROM AUTHOR]

• DeST is an effective and accurate tool to predict dynamic thermal load for poultry buildings. • Annual maximum cooling and heating load decreased 11.10% and 4.81% when thermal performances meet standards requirements. • Tightness was adjusted from "loose" to "tight" could lead maximum hourly heating and cooling load declined 19.90% and 5.72%. • Ventilation rate should be decreased according to the actual stocking density/mortality. • The toolkit can be used to suggest relevant energy saving measures for hen houses. Understanding the dynamic heating and cooling load of poultry houses enables more precise environmental housing control; however, there is a lack of efficient tools for evaluating and predicting these loads. The objectives of this study were to develop and validate a toolkit to simulate the hourly building load throughout a year, simulate the base room temperature, and investigate the thermal performance of a commercial poultry house in Beijing. Various infiltrating air volumetric flow rates (0.2, 0.6, 1.0, and 2.0 air changes per hour) and total ventilation rates under three mortality levels (5.0%, 10.0%, and 15.0%) were used for the simulation to compare the annual heating and cooling load (AHL and ACL). The correlations between measured and simulated data were 0.99 for indoor air temperature and 0.90 for relative humidity. Based on the simulation results, the base room temperature was −9.2 to 42.2 °C throughout the year. The recommended temperature was met only 38.80% of the year, indicating that extra energy must be consumed to maintain a suitable temperature all year. Air inlets (windows and doors) were altered to meet Chinese energy efficiency standards, which decreased the maximum AHL and ACL by approximately 11.10% and 4.81%, respectively. When the tightness of envelope construction was adjusted from "loose" to "medium" and from "loose" to "tight", the maximum AHL decreased by 15.45% and 19.86% and the maximum ACL decreased by 4.45% and 5.72%, respectively. Decreasing the ventilation rate reduced the hourly cooling and heating load from 12.51 to 50.04 KW and 3.75–15.01 KW, respectively, due to different mortality rates when the air temperature difference was 5.0 °C and 20.0 °C. The proposed simulation toolkit is an effective and accurate tool for evaluating and predicting dynamic building loads for poultry houses. Hourly dynamic thermal simulations throughout the year can accurately determine potential problems in housing systems and lead to appropriate energy-saving strategies. [ABSTRACT FROM AUTHOR]

In this paper a novel solar combined heat and power (CHP) system incorporating absorption heat pump (AHP) driven by mid-temperature solar heat and exhaust heat is proposed to improve solar energy utilization and electricity power generation. To validate thermodynamic performance of the proposed system, a case study is carried out based on 1 MW solar tower power plant located in Beijing. Depending on the well-developed mathematical model in accordance with actual equipment, the relevant module is coded in TRNSYS application environment. Besides, control and operation strategy is deeply analyzed to efficiently utilize solar energy with principal of cascade utilization. The dynamic simulation effectively predicts thermodynamic performance under the different operation modes in a typical winter day. Results indicate that flexible heating supply of the proposed system can meet well with user-generated heating loads. The AHP system recovers the condensate heat of 914 MJ with the average COP of 1.52. The proposed system generates the additional power of 217 kWh due to the regenerative cycle. Accompanying with power generation of 6214 kWh and useable thermal energy of 14502 MJ of the proposed system, the overall utilization efficiency of solar energy is up to 15.96% with the increase of 4.55 percentages. • Propose a novel CHP system with heat recovery process based on STP tower plant. • Develop mathematical models and simulation modules in TRNSYS application. • Develop control and operation strategy for efficient utilization of solar energy. • Simulate thermodynamic performances of the CHP system at 1 min intervals. [ABSTRACT FROM AUTHOR]