检索结果-内蒙古大学图书馆

PM_(10) dust emission in the Erenhot-Huailai zone of northern China based on model simulation

Journal of Arid Land 2025年第3期17卷 324-336页

作者： WANG Yong YAN Ping WU Wei WANG Yijiao HU Chanjuan LI Shuangquan Institute of Geographical Sciences Henan Academy of SciencesZhengzhou 450052China Faculty of Geographical Science Beijing Normal UniversityBeijing 100875China State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal UniversityBeijing 100875China College of Urban and Environmental Sciences Hubei Normal UniversityHuangshi 435002China

The Erenhot-Huailai zone, as an important dust emission source area in northern China, affects the air quality of Beijing City, Tianjin City, and Hebei Province and human activities in this zone have a profound impact on surface dust emission. In order to explore the main source areas of surface dust emission and quantify the impacts of human activities on surface dust emission, we investigated the surface dust emission of different land types on the Erenhot-Huailai zone by model simulation, field observation, and comparative analysis. The results showed that the average annual inhalable atmospheric particles(PM_(10)) dust emission fluxes in arid grassland, Hunshandake Sandy Land, semi-arid grassland,semi-arid agro-pastoral area, dry sub-humid agro-pastoral area, and semi-humid agro-pastoral area were 4.41, 0.71, 3.64, 1.94, 0.24, and 0.14 t/hm^(2), respectively, and dust emission in these lands occurred mainly from April to May. Due to the influence of human activities on surface dust emission, dust emission fluxes from different land types were 1.66–4.41 times greater than those of their background areas, and dust emission fluxes from the main dust source areas were 1.66–3.89 times greater than those of their background areas. According to calculation, the amount of PM_(10) dust emission influenced by human disturbance accounted for up to 58.00% of the total dust emission in the study area. In addition, the comparative analysis of model simulation and field observation results showed that the simulated and observed dust emission fluxes were relatively close to each other, with differences ranging from 0.01 to 0.21 t/hm^(2) in different months, which indicated that the community land model version 4.5(CLM4.5) had a high accuracy. In conclusion, model simulation results have important reference significance for identifying dust source areas and quantifying the contribution of human activities to surface dust emission.

关键词： northern China classification of land type model simulation dust emission human disturbance

来源：评论

学校读者我要写书评

暂无评论

model simulation of soil carbon dynamics with stand development in Japanese cedar (Cryptomeria japonica) plantations

引用

ECOLOGICAL RESEARCH 2007年第3期22卷 515-526页

作者： Shuto, Katsuyuki Nakane, Kaneyuki Hiroshima Univ Grad Sch Biosphere Sci Div Environm Dynam & Management Higashihiroshima 7398521 Japan

Soil carbon cycling in Japanese cedar plantations after clear-cutting over time was calculated with and without consideration of plantation management (pruning and thinning) using a mathematical model. The model employed a daily time step and used daily air temperature and observed precipitation near the plantations. The results of these calculations of above-ground biomass, carbon flow and accumulation were compared with the field observations reported by Shutou and Nakane (Ecol Res 19:233-244, 2004) observed in the Hiroshima prefecture. For example, the carbon accumulation and total soil respiration rate calculated with the inclusion of plantation management for a 60-year-old stand were 104 and 4.8 t C ha(-1) year(-1), compared with a field observation of 110 and 4.5 t C ha(-1) year(-1), respectively. The results calculated for carbon flow and accumulation were not significantly different from the field observations, assessed using one-way analysis of variance (P > 0.05), and the mean relative errors were very small (e.g., the maximum was 0.05). Consequently, it is suggested that the dynamics of carbon cycling following clear-cutting of a Japanese cedar plantation can be simulated realistically using these calculations with and without consideration of plantation management. Moreover, it is possible that the calculation without consideration of plantation management can yield the change of carbon cycling over time, even if the history of forest management in the plantations is unknown. It is expected that this study will contribute to the development of a more versatile model.

关键词： forest management Japanese cedar plantation model simulation soil carbon dynamics validity of calculation

来源：评论

学校读者我要写书评

暂无评论

model simulation of the patient flow through a screening centre for diabetic retinopathy

引用

ACTA OPHTHALMOLOGICA SCANDINAVICA 2005年第6期83卷 678-686页

作者： Hansen, AB Hansen, RN Colding-Jorgensen, M Borch-Johnsen, K Lund-Andersen, H Univ Copenhagen Dept Ophthalmol Herlev Hosp DK-2730 Herlev Denmark Novo Nordisk AS DK-2880 Bagsvaerd Denmark Steno Diabet Ctr DK-2820 Gentofte Denmark Aarhus Univ Fac Hlth Sci Aarhus Denmark

Purpose: To construct a quantitative, flexible and simplified mathematical model of the patient flow through the Eye Clinic at the Steno Diabetes Centre (SDC) in order to enable rational dimensioning and assess the effects of modifications. Methods: Patient data were drawn from the Eye Care database at the SDC. A simple patient flow model was constructed, allowing simultaneous adjustments of all variables, and the model was tested. Two scenarios were simulated: (1) adjusting the algorithm that assigns the follow-up intervals, and (2) increasing the population size to include all patients with diabetes in Copenhagen County. Results: The model can describe the patient flow under steady state conditions, but is less precise in predicting transient changes with the present set-up. Accordingly all simulations were run for a substantial number of iterations. The two scenarios illustrate the usefulness of the model by calculating the required photographic examination capacity for the specific population, thereby allowing better estimations of future dimensioning of the organization. Conclusion: The study presents a patient flow model that can be used to illustrate the effects of proposed changes prior to their implementation, specifically with respect to the capacity of the system.

关键词： model simulation patient flow diabetic retinopathy screening capacity

来源：评论

学校读者我要写书评

暂无评论

Facilitated Prediction of Micropollutant Degradation via UV-AOPs in Various Waters by Combining model simulation and Portable Measurement

引用

Engineering 2024年第6期37卷 87-95页

作者： Yanyan Huang Mengkai Li Zhe Sun Wentao Li James R.Bolton Zhimin Qiang Key Laboratory of Drinking Water Science and Technology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China Department of Civil and Environmental Engineering University of AlbertaEdmontonAB T6G 1H9Canada State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China

The degradation of micropollutants in water via ultraviolet(UV)-based advanced oxidation processes(AOPs)is strongly dependent on the water *** reactive radicals(RRs)formed in UV-AOPs have different reaction selectivities toward water matrices and degradation efficiencies for target ***,process selection and optimization are *** study developed a facilitated prediction method for the photon fluence-based rate constant for micropollutant degradation(K′_(p,MP))in various UV-AOPs by combining model simulation with portable *** methods for measuring the scavenging capacities of the principal RRs(RRSCs)involved in UV-AOPs(i.e.,HO^(·),SO_(4)^(·-),and Cl^(·))using a mini-fluidic photoreaction system were *** simulation models consisted of photochemical,quantitative structure–activity relationship,and radical concentration steady-state approximation *** RRSCs were determined in eight test waters,and a higher RRSC was found to be associated with a more complex water ***,by taking sulfamethazine,caffeine,and carbamazepine as model micropollutants,the k′_(p,MP) values in various UV-AOPs were predicted and further verified experimentally.A lower k′_(p,MP) was found to be associated with a higher RRSC for a stronger RR competition;for example,k′_(p,MP) values of 130.9 and 332.5 m^(2) einstein^(–1),respectively,were obtained for carbamazepine degradation by UV/H_(2)O_(2) in the raw water(RRSC=9.47×10^(4) s^(-1))and sand-filtered effluent(RRSC=2.87×10^(4) s^(-1))of a drinking water treatment *** developed method facilitates process selection and optimization for UV-AOPs,which is essential for increasing the efficiency and cost-effectiveness of water treatment.

关键词： UV-AOPs Micropollutant degradation Reactive radicals Water matrix model simulation

来源：评论

学校读者我要写书评

暂无评论

Production of Picea abies in south-east Norway in response to climate change:: A case study using process-based model simulation with field validation

引用

SCANDINAVIAN JOURNAL OF FOREST RESEARCH 2002年第1期17卷 35-46页

作者： Zheng, D Freeman, M Bergh, J Rosberg, I Nilsen, P Norwegian Forest Res Inst NO-1432 As Norway Swedish Univ Agr Sci Dept Prod Ecol SE-75007 Uppsala Sweden

A process-based model was used to simulate biomass production of Norway spruce under both current climate and climate change scenarios. The model was parameterized for Nordmoen in south-cast Norway using real climate data for the period 1987-1989. The model was applied to predict the biomass production responses to three climate change scenarios. The results showed that net primary production (NPP) increased by 7% under an elevated annual mean air temperature of 4degreesC from the current 10.1 t dry mass ha (-1) yr (-1). A doubled current ambient CO, concentration significantly increased NPP by 36%. The scenario of both elevated temperature and elevated CO2 concentration led to an increase in the NPP of 49%, higher than the sum of the two effects acting singly. The results also showed that forest production responses to climate change depend on the conditions of climate used for reference.

关键词： biomass production CO2 concentration and temperature elevations model simulation Norway spruce

来源：评论

学校读者我要写书评

暂无评论

Time-Frequency Distribution Characteristic and model simulation of Photovoltaic Series Arc Fault With Power Electronic Equipment

引用

IEEE JOURNAL OF PHOTOVOLTAICS 2019年第4期9卷 1128-1137页

作者： Chen, Silei Li, Xingwen Xie, Zhimin Meng, Yu Xi An Jiao Tong Univ State Key Lab Elect Insulat & Power Equipment Xian 710049 Shaanxi Peoples R China

In the photovoltaic (PV) system, the electrical characterization of series arc faults would he inevitably interfered by power electronic equipment. Existing methods are unable to effectively separate clear arc fault features from these influence factors, forming some unwanted detection barriers. In this paper, series arc fault experiments are conducted in PV systems with different kinds of power electronic equipment first. Having analyzed PV series arc faults through the existing linear transform, arc faults are hard to be identified in the undesired switching frequency band and harmonics because of noise interferences. Through establishment of effectiveness evaluation index, more performance limitations are discovered in low- and high-frequency bands for the bandpass filter effect of the linear transform. Then the arc fault identification in high and switching frequency bands become much easier after the investigation of the bilinear transform with higher time-frequency resolution. However, the performance is not obviously improved in the low-frequency band because of the cross term. Next, arc fault features in low and switching frequency hands would he more obvious through application of the adaptive transform. Besides, performances just have a slight decrease in the high-frequency band. These better time-frequency distributions are of great benefit to improve the detection accuracy and expand the application scope. Finally, the arc fault model is proposed to acquire the simulated data in the PV system with the power electronic equipment. It is found that the power electronic equipment would seriously interfere arc fault behaviors in the low and switching frequency bands.

关键词： Effectiveness evaluation frequency characteristic model simulation power electronic equipment PV series arc fault time-frequency distribution

来源：评论

学校读者我要写书评

暂无评论

The cold ocean warm land pattern: model simulation and relevance to climate change detection

引用

JOURNAL OF CLIMATE 1998年第11期11卷 2743-2763页

作者： Broccoli, AJ Lau, NC Nath, MJ Princeton Univ NOAA Geophys Fluid Dynam Lab Princeton NJ 08542 USA

Surface air temperatures from a 1000-yr integration of a coupled atmosphere-ocean model with constant forcing are analyzed by using a method that decomposes temperature variations into a component associated with a characteristic spatial structure and a residual. The structure function obtained from the coupled model output is almost identical to the so-called cold ocean-warm land (COWL) pattern based on observations, in which above-average spatial mean temperature is associated with anomalously cold oceans and anomalously warm land. This pattern features maxima over the high-latitude interiors of Eurasia and North America. The temperature fluctuations at the two continental centers exhibit almost no temporal correlation with each other. The temperature variations at the individual centers are related to teleconnection patterns in sea level pressure and 500-mb height that are similar to those identified in previous observational and modeling studies. As in observations, variations in the polarity and amplitude of this structure function are an important source of spatially averaged surface air temperature variability. Results from parallel integrations of models with more simplified treatments of the ocean confirm that the contrast in thermal inertia between land and ocean is the primary factor for the existence of the COWL pattern, whereas dynamical air-sea interactions do not play a significant role. The internally generated variability in structure function amplitude in the coupled model integration is used to assess the importance of the upward trend in the amplitude of the observed structure function over the last 25 yr. This trend, which has contributed to the accelerated warming of Northern Hemisphere temperature over recent decades, is unusually large compared with the trends generated internally by the coupled model. If the coupled model adequately estimates the internal variability of the real climate system, this would imply that the recent upturn in the

关键词： .Residual North America coupled model characteristic surface air temperature temperature variations COWL model simulation temperature fluctuations Atmosphere–Ocean Geophysical Fluid spatial mean yr integration structure function

来源：评论

学校读者我要写书评

暂无评论

Dynamic changes in spatial microbial distribution in mixed-population biofilms: Experimental results and model simulation

引用

WATER SCIENCE AND TECHNOLOGY 1995年第8期32卷 67-74页

作者： Okabe, S Hirata, K Watanabe, Y PACIFIC CONSULTANTS CO LTD YODOGAWA KUOSAKA 532JAPAN

Dynamic changes in spatial microbial distribution in mixed-population biofilms were experimentally determined using a microslicer technique and simulated by a biofilm accumulation model (BAM). Experimental results were compared with the model simulation. The biofilms cultured in partially submerged rotating biological contactors (RBC) with synthetic wastewater were used as test materials. Experimental results showed that an increase of substrate loading rate (i.e., organic carbon and NH4-N) resulted In the microbial stratification in the biofilms. Heterotrophs defeated nitrifiers and dominated in the outer biofilm, whereas nitrifiers were diluted out in the outer biofilm and forced into the inner biofilm. At higher organic loading rates, a stronger stratified microbial spatial distribution was observed, which imposed a severe internal oxygen diffusion limitation cn nitrifiers and resulted in the deterioration of nitrification efficiency. model simulations described a general trend of the stratified biofilm structure. However, the actual stratification was stronger than the simulated results. For implication in the reactor design, when the specific carbon loading rate exceeds a certain limit, nitrification will be deteriorated or require a long start-up period due to the interspecies competition resulting in oxygen diffusion limitation. The extend of microbial stratification in the biofilm is especially important for determination of feasibility of nitrification in the presence of organic matters.

关键词： population dynamics nitrifiers heterotrophs interspecies competition biofilms model simulation

来源：评论

学校读者我要写书评

暂无评论

Impact of long-range desert dust transport on coastal East Asia: analysis of urban dust concentration and wet deposition with model simulation

引用

AIR QUALITY ATMOSPHERE AND HEALTH 2017年第3期10卷 325-337页

作者： Zhang, Zhenxi Zhou, Wen Wenig, Mark Yang, Liangui Inner Mongolia Univ Sch Math Sci Res Inst Fluid Dynam Hohhot Peoples R China Inner Mongolia Univ Technol Dept Environm Engn Hohhot Peoples R China City Univ Hong Kong Sch Energy & Environm Tat Chee Ave Kowloon Hong Kong Peoples R China Ludwig Maximilians Univ Munchen Meteorol Inst Munich Germany

Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model simulations for dust in 2007 are applied in this study to investigate the impact of long-range desert dust transport on the dust concentration and wet deposition in coastal cities of East Asia: Shanghai and Hong Kong. The temporal variation of dust concentrations in both Shanghai and Hong Kong exhibits a maximum in spring (May), with a majority of Gobi dust, which accounts for 88 % in Shanghai and 58 % in Hong Kong in the lower troposphere. Correspondingly, the peaks of convective and large-scale wet deposition in May in Shanghai are controlled by Gobi dust, with a contribution of 74-83 %. The wet deposition of dust in summer is affected mainly by strong convective precipitation and dominated by Taklamakan dust, with a contribution of 31-47 % in Shanghai and 19-37 % in Hong Kong, followed by Arabian and Karakum-Kavir dusts. The wet deposition in spring (April) is caused mainly by large-scale precipitation, with a majority of Gobi dust, which accounts for 57 % in Shanghai and 71 % in Hong Kong, followed by Sahara and Taklamakan dusts. The temporal variation of wet deposition of dust in Shanghai is affected mainly by the dust concentration, while the variation in Hong Kong is controlled by both dust concentration and convective precipitation.

关键词： Dust Wet deposition Transport model simulation

来源：评论

学校读者我要写书评

暂无评论

Exploration of chemical composition effects on the autoignition of two commercial diesels: Rapid compression machine experiments and model simulation

引用

COMBUSTION AND FLAME 2019年第Jun.期204卷 204-219页

作者： Yu, Liang Wang, Sixu Wang, Wenyu Qiu, Yue Qian, Yong Mao, Yebing Lu, Xingcai Shanghai Jiao Tong Univ Sch Mech Engn Key Lab Power Machinery & Engn MOE 800 Dongchuan Rd Shanghai 200240 Peoples R China

Chemical composition difference widely exists in real fuels, and the composition difference will affect the fuel autoignition and heat release in HCCI-based advanced engines. This study aims to explore the composition effects on autoignition by comparing the autoignition characteristics of two commercial diesels (China Stage-V and Stage-VI). The main composition difference is that Stage-V diesel has a higher paraffin content and a lower naphthene content than Stage-VI diesel. Ignition delay times (IDTs) of the two diesels were measured in a heated rapid compression machine at equivalence ratios of 0.37-1.25, pressures of 10-20 bar, and temperatures of 687-865 K. It is found that the difference in the total IDTs of the two diesels varies with the temperature range, and the first-stage IDTs of Stage-V diesel are much shorter than those of Stage-VI diesel. The IDT discrepancies were appropriately explained using the composition difference between the two diesels. model simulation was carried out using a ternary and a five-component diesel surrogate coupled with an updated kinetic model. simulation results show that the composition effects on the autoignition of the two diesels can be well captured by the two surrogates, where the ternary and five-component surrogates agree well with Stage-V and Stage-VI diesels, respectively. To further reveal the intrinsic mechanism of the composition effects, low-temperature reactivity difference between the two surrogates was interpreted from a kinetic perspective. Rate of production (ROP) analysis on OH radical confirms that the addition of decalin in the five-component surrogate is primarily responsible for the longer first-stage IDT compared to the ternary surrogate. Since the two surrogates capture the composition difference and autoignition characteristics of the two diesels, the conclusion from the kinetic analysis will help understand the composition effects on the autoignition of the diesels. (C) 2019 The Combustion Institut

关键词： Diesel Autoignition Composition effect Ignition delay time Rapid compression machine model simulation

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：