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Phosphorus Fertilizer Effect in Sugarcane Red Soil and Its Loss Risk Assessment under Different Phosphorus Application Rates 被引量:1
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作者 朱晓晖 曾艳 +4 位作者 黄金生 区惠平 周柳强 谢如林 谭宏伟 《Agricultural Science & Technology》 CAS 2017年第12期2372-2377,共6页
[Objectives] The soil phosphorus balance and potential risk of phosphorus loss under different phosphorus application rates in sugarcane red soil in Guangxi were evaluated to provide reference for scientific and ratio... [Objectives] The soil phosphorus balance and potential risk of phosphorus loss under different phosphorus application rates in sugarcane red soil in Guangxi were evaluated to provide reference for scientific and rational application of phos- phorus fertilizer and reduction of environmental pollution. [Methods] A field trial and simulated rainfall experiment were carried out. In the field experiment, five phospho- rus levels (0, 75, 150, 300 and 600 kg P2OJhm2) were set, the yield of sugarcane stems and leaves were measured, and their phosphorus content was determined to obtain aboveground P accumulation and P surplus in soil. After sugarcane harvest- ing, calcium magnesium phosphate and potassium dihydrogen phosphate were ap- plied to soil with different levels of phosphorus to conduct the simulated rainfall ex- periment based on monthly rainfall from May to September in Guangxi during 2000-2015. The leachate was collected to analyze the concentration and total amount of phosphorus to obtain the regression equations between available phos- phorus content in soil and the increase of phosphorus concentration in leachate. [Results] Sugarcane yield increased significantly when phosphorus application rate was 150 kg P:~OJhm2. When phosphorus application rate exceeded this value, the yield of sugarcane stems and aboveground part was also significantly higher than the treatment without phosphorus application, but the increase of yield was similar to the treatment with phosphorus application rate of 150 kg P2OJhm2. According to the relationship equation between phosphorus application rate and soil Olsen-P con- tent as well as the relationship equations between the increment of P concentration in leachate and soil Olsen-P content in the treatments with calcium magnesium phosphate and KH2PO4, the increment of P concentration in leachate was 0.02-0.04 mg/L when phosphorus application rate was 75 kg P2OJhm2; the increment of P concentration in leachate was 0.07-0.10 mg/L as phosphorus application rate was 600 kg P2OJhm2. [Conclusions] The reasonable application rate of phosphorus fer- tilizer for sugarcane is 150 kg P2Or/hm2. However, long-term continuous application of phosphorus fertilizer can promote the enhancement of available phosphorus con- tent in soil and increase the risk of phosphorus loss from sugarcane fields. 展开更多
关键词 SUGARCANE Red soil PHOSPHORUS loss risk
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Theory and Application of Loss of Life Risk Analysis for Dam Break 被引量:2
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作者 孙月峰 钟登华 +1 位作者 李明超 李颖 《Transactions of Tianjin University》 EI CAS 2010年第5期383-387,共5页
The loss of life risk evaluation model for dam break is built in this paper.By using an improved Monte Carlo method,the overtopping probability induced by concurrent flood and wind is calculated,and the Latin Hypercub... The loss of life risk evaluation model for dam break is built in this paper.By using an improved Monte Carlo method,the overtopping probability induced by concurrent flood and wind is calculated,and the Latin Hypercube Sampling is used to generate random numbers.The Graham method is used to calculate the loss of life resulting from dam failure.With Dongwushi reservoir located at Hebei Province taken as an example,the overtopping probability induced by concurrent flood and wind is calculated as 4.77×10-6.Los... 展开更多
关键词 overtopping probability loss of life risk risk assessment dam safety management
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Risk of Hearing Loss Caused by Multiple Acoustic Impulses in the Framework of Biovariability 被引量:2
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作者 Hongyun Wang Wesley A. Burgei Hong Zhou 《Health》 2018年第5期604-628,共25页
We consider the hearing loss injury among subjects in a crowd with a wide spectrum of individual intrinsic injury probabilities due to biovariability. For multiple acoustic impulses, the observed injury risk of a crow... We consider the hearing loss injury among subjects in a crowd with a wide spectrum of individual intrinsic injury probabilities due to biovariability. For multiple acoustic impulses, the observed injury risk of a crowd vs the effective combined dose follows the logistic dose-response relation. The injury risk of a crowd is the average fraction of injured. The injury risk was measured in experiments as follows: each subject is individually exposed to a sequence of acoustic impulses of a given intensity and the injury is recorded;results of multiple individual subjects were assembled into data sets to mimic the response of a crowd. The effective combined dose was adjusted by varying the number of impulses in the sequence. The most prominent feature observed in experiments is that the injury risk of the crowd caused by multiple impulses is significantly less than the value predicted based on assumption that all impulses act independently in causing injury and all subjects in the crowd are statistically identical. Previously, in the case where all subjects are statistically identical (i.e., no biovariability), we interpreted the observed injury risk caused by multiple impulses in terms of the immunity effects of preceding impulses on subsequent impulses. In this study, we focus on the case where all sound exposure events act independently in causing injury regardless of whether one is preceded by another (i.e., no immunity effect). Instead, we explore the possibility of interpreting the observed logistic dose-response relation in the framework of biovariability of the crowd. Here biovariability means that subjects in the crowd have their own individual injury probabilities. That is, some subjects are biologically less or more susceptible to hearing loss injury than others. We derive analytically the distribution of individual injury probability that produces the observed logistic dose-response relation. For several parameter values, we prove that the derived distribution is mathematically a proper density function. We further study the asymptotic approximations for the density function and discuss their significance in practical numerical computation with finite precision arithmetic. Our mathematical analysis implies that the observed logistic dose-response relation can be theoretically explained in the framework of biovariability in the absence of immunity effect. 展开更多
关键词 risk of Significant Hearing loss INJURY DOSE-RESPONSE Relation for MULTIPLE ACOUSTIC IMPULSES Biovariability A Crowd With Heterogeneous Individual INJURY Probabilities
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Recognition and Measurement of Losses Caused by Systematic Risk in Damages of False Statements
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作者 杜莹芬 张文珂 《China Economist》 2014年第2期114-125,共12页
Based on the single-factor market model, this paper examines the confirmation basis and measurement of the losses arising from systematic risk in the civil damages of false statements. The paper argues that the system... Based on the single-factor market model, this paper examines the confirmation basis and measurement of the losses arising from systematic risk in the civil damages of false statements. The paper argues that the systematic risk not only affects the investment in securities during times of financial crisis, but also causes losses in daily securities trading. The paper carries out an empirical analysis on the existence of fl coefficient for China's listed companies within a period of one year, and examines the impact of systematic risk on the losses of investors. The civil damages of false statements should take full account of the losses arising from systematic risk. After analysis, the paper uses the correlation coefficient to represent the ratio of losses arising from systematic risk of all the transactions of a particular stock during a certain period of time, and tries to develop two methods to measure the damages after adjusting the losses caused by the systematic risk. The paper has a theoretical foundation for the estimation of losses caused by systematic risk, and matches the risks and returns. The result of the paper has provided an effective method of calculation in the determination of reasonable damages in the case of China Langfang Development Co., Ltd. 展开更多
关键词 losses arising from systematic risk civil damages false statement correlationcoefficient
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Effects of Orlistat - induced Weight Loss on Cardiovascular Risk Factors in Obese Chinese Subjects
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作者 徐明彤 吴木潮 +3 位作者 黎锋 周淑娴 程桦 傅祖植 《South China Journal of Cardiology》 CAS 2003年第1期1-4,共4页
Objectives To observe the influence of weight loss induced by orlistat on several cardiovascular diseases risk factors in obese Chinese subjects. Methods Sixty obese Chinese patients participated in a 24 week clinical... Objectives To observe the influence of weight loss induced by orlistat on several cardiovascular diseases risk factors in obese Chinese subjects. Methods Sixty obese Chinese patients participated in a 24 week clinical trial. Participants were prescribed a slightly hypocaloric diet and exercise, then they were randomly assigned double -blind treatment with either orlistat 120 mg three times a day or placebo. Their body weight, blood pressure, fasting glucose, insulin, HbA1c, and serum lipid profile were performed before and after the weight loss intervention. Results After 24 weeks, orlistat -treated group lost more of their body weight than placebo group (6. 66 ± 0. 52 kg, 8. 44±4.08% and 1. 98 ± 0. 44 kg, 2. 44±1. 74 % , respectively, P < 0. 05) . Moreover, after treatment, orlistat - treated patients showed significant decreases in serum levels of total cholesterol, low density lipoprotein - cholesterol and high density lipoprotein - cholesterol ( P < 0.01), but in placebo group we found no change. Both systolic blood pressure and diastolic blood pressure fell significantly in orlistat - treated group. Fasting glucose and HOMA - IR in orlistat - treated group was distinctly reduced if compared with placebo group. Conclusions Weight loss resulting from orlistat treatment and slightly hypocaloric diet has produced favorable effects on several cardiovascular risk factors in obese Chinese subjects. 展开更多
关键词 Orlistat Weight loss Cardiovascular risk factors
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Smoking increases risk of tooth loss: A meta-analysis of the literature
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作者 Fumihito Sato Masashi Sawamura +4 位作者 Miki Ojima Keiko Tanaka Takashi Hanioka Hideo Tanaka Keitaro Matsuo 《World Journal of Meta-Analysis》 2013年第1期16-26,共11页
AIM: To quantitatively evaluate the impact of smoking on tooth loss.METHODS: We performed a Pub Med search to identify published articles that investigated the risk of tooth loss by smoking, from which RRs and their v... AIM: To quantitatively evaluate the impact of smoking on tooth loss.METHODS: We performed a Pub Med search to identify published articles that investigated the risk of tooth loss by smoking, from which RRs and their variance with characteristics of each study were extracted. The random-effects models were used to derive a pooled effect across studies. Potential sources of heterogeneity on the characteristics of the study and their influence on the pooled effect size were investigated using metaregression models. RESULTS: We identified 24 studies containing a total of 95973 participants for analysis. The pooled RR of ever-smokers compared with never- smokers was 1.73(95%CI: 1.60-1.86, P < 0.001). In meta-regression analysis, only the mean age of participants alone was identified as a statistically significant source of heterogeneity. The effect of smoking on tooth loss was stronger when the mean age of study participants was higher, indicating possible enhancement of tooth loss due to aging by smoking. RR was significantly lower in former smokers(1.49, 95%CI: 1.32-1.69, P < 0.001) than in current smokers(2.10, 95%CI: 1.87-2.35, P < 0.001), indicating the substantial benefit of smoking cessation for reducing the risk of tooth loss.CONCLUSION: Smoking is an independent risk factor for tooth loss regardless of many other confounders. Smoking cessation may attenuate this effect. 展开更多
关键词 META-ANALYSIS Oral health Relative risk SMOKING Tooth loss
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Risk of Hearing Loss Injury Caused by Multiple Flash Bangs on a Crowd
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作者 Hongyun Wang Wesley A. Burgei Hong Zhou 《American Journal of Operations Research》 2018年第4期239-265,共27页
A flash bang is a non-lethal explosive device that delivers intensely loud bangs and bright lights to suppress potentially dangerous targets. It is usually used in crowd control, hostage rescue and numerous other miss... A flash bang is a non-lethal explosive device that delivers intensely loud bangs and bright lights to suppress potentially dangerous targets. It is usually used in crowd control, hostage rescue and numerous other missions. We construct a model for assessing quantitatively the risk of hearing loss injury caused by multiple flash bangs. The model provides a computational framework for incorporating the effects of the key factors defining the situation and for testing various sub-models for these factors. The proposed model includes 1) uncertainty in the burst point of flash bang mortar, 2) randomness in the dispersion of multiple submunitions after the flash bang mortar burst, 3) decay of acoustic impulse from a single submunition to an individual subject along the ground surface, 4) the effective combined sound exposure level on an individual subject caused by multiple submunitions at various distances from the subject, and 5) randomness in the spatial distribution of subjects in the crowd. With the mathematical model formulated, we seek to characterize the overall effect of flash bang mortar in the form of an effective injury area. We carry out simulations to study the effects of uncertainty and randomness on the risk of hearing loss injury of the crowd. The proposed framework serves as a starting point for a comprehensive assessment of hearing loss injury risk, taking into consideration all realistic and relevant features of flash bang mortar. It also provides a platform for testing and updating component models. 展开更多
关键词 risk of SIGNIFICANT HEARING loss Mathematical Framework for Assessing INJURY risk Effective INJURY Area Decay of Acoustic Impulse along Ground Surface DOSE-RESPONSE Relation Fluctuations in Actual INJURY Numbers
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Assessment of Intangible Losses in Earthquake Engineering
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作者 Jaime García-Pérez Orlando Díaz-López Eric García-López 《Open Journal of Civil Engineering》 2024年第3期469-485,共17页
In order to find optimum design parameters in earthquake engineering, an objective function is optimized. This function comprises the initial cost of a structure and the cost due to the damage of earthquakes. Intangib... In order to find optimum design parameters in earthquake engineering, an objective function is optimized. This function comprises the initial cost of a structure and the cost due to the damage of earthquakes. Intangible losses may be included in the latter, such as how much society is willing to invest to preserve a human life. In this paper, the expression of the objective function is developed in terms of the seismic design coefficient, and the aforementioned intangible loss is calculated from both the individual point of view and that of society. The calculation of the intangible is based on utility curves. Finally, optimum seismic design coefficients are calculated for a firm ground site. 展开更多
关键词 Seismic risk Optimum Coefficients Structural Reliability Intangible losses UTILITY
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基于@RISK番茄潜叶蛾对我国番茄产业造成的经济损失评估 被引量:5
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作者 席曼姝 王振霖 +4 位作者 刘孝贤 李志红 张鑫 吕昭智 韩鹏 《生物安全学报》 CSCD 北大核心 2022年第4期300-308,共9页
【目的】新发恶性外来入侵物种番茄潜叶蛾的入侵对我国番茄产业的安全生产造成了极大威胁。本文利用@RISK模型对化学防治、生物防治和理化诱控3种不同防治场景下我国番茄产业的潜在经济损失和投入防治后可挽回的经济损失进行综合评估,... 【目的】新发恶性外来入侵物种番茄潜叶蛾的入侵对我国番茄产业的安全生产造成了极大威胁。本文利用@RISK模型对化学防治、生物防治和理化诱控3种不同防治场景下我国番茄产业的潜在经济损失和投入防治后可挽回的经济损失进行综合评估,结果可为我国番茄潜叶蛾综合防治体系的构建提供参考。【方法】基于国内外文献收集到的番茄潜叶蛾危害数据(危害率、番茄产量损失率、防治成本和防治效果),结合全国农产品商务信息公共服务平台、FAO获得我国番茄的种植面积、产量及价格等相关数据,利用@RISK模型对不防治场景和3种不同防治场景下的番茄产业的经济损失进行评估。【结果】番茄潜叶蛾在不防治场景下每年给我国番茄产业造成的经济损失总量在(8226165.67~41903398.26)万元,在化学防治(使用合成杀虫剂)、生物防治(释放天敌昆虫和微生物制剂)和理化诱控(基于灯光和合成性信息素的诱杀产品)3种不同防治场景下能有效挽回经济损失,分别为89.83%、87.90%和89.19%。【结论】基于不同的防治场景能够有效挽回番茄潜叶蛾造成的经济损失,面对该害虫在我国的严峻扩散形势,建议各级政府和行业部门应高度重视并进一步加强番茄潜叶蛾的防控,保障我国番茄产业的安全生产。 展开更多
关键词 番茄潜叶蛾 番茄 经济损失 @risk
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基于边界自适应SMOTE和Focal Loss函数改进LightGBM的信用风险预测模型 被引量:8
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作者 陈海龙 杨畅 +1 位作者 杜梅 张颖宇 《计算机应用》 CSCD 北大核心 2022年第7期2256-2264,共9页
针对信用风险评估中数据集不平衡影响模型预测效果的问题,提出一种基于边界自适应合成少数类过采样方法(BA-SMOTE)和利用FocalLoss函数改进LightGBM损失函数的算法(FLLightGBM)相结合的信用风险预测模型。首先,在边界合成少数类过采样(B... 针对信用风险评估中数据集不平衡影响模型预测效果的问题,提出一种基于边界自适应合成少数类过采样方法(BA-SMOTE)和利用FocalLoss函数改进LightGBM损失函数的算法(FLLightGBM)相结合的信用风险预测模型。首先,在边界合成少数类过采样(Borderline-SMOTE)的基础上,引入自适应思想和新的插值方式,使每个处于边界的少数类样本生成不同数量的新样本,并且新样本的位置更靠近原少数类样本,以此来平衡数据集;其次,利用FocalLoss函数来改进LightGBM算法的损失函数,并以改进的算法训练新的数据集以得到最终结合BA-SMOTE方法和FLLightGBM算法建立的BA-SMOTE-FLLightGBM模型;最后,在LendingClub数据集上进行信用风险预测。实验结果表明,与其他不平衡分类算法RUSBoost、CUSBoost、KSMOTE-AdaBoost和AK-SMOTE-Catboost相比,所建立的模型在G-mean和AUC两个指标上都有明显的提升,提升了9.0%~31.3%和5.0%~14.1%。以上结果验证了所提出的模型在信用风险评估中具有更好的违约预测效果。 展开更多
关键词 信用风险 不平衡数据 过采样 LightGBM Focalloss
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Effect of Phopshate Fertilizer and Manure on Crop Yield, Soil P Accumulation, and the Environmental Risk Assessment 被引量:14
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作者 LIU Jian-ling LIAO Wen-hua ZHANG Zuo-xin ZHANG Hai-tao WANG Xin-jun MENG Na 《Agricultural Sciences in China》 CAS CSCD 2007年第9期1107-1114,共8页
Phosphorus (P) applied from fertilizer and manure is important in increasing crop yield and soil fertility; however, excessive uses of phosphate fertilizer and manure may also increase P loss from agricultural soils... Phosphorus (P) applied from fertilizer and manure is important in increasing crop yield and soil fertility; however, excessive uses of phosphate fertilizer and manure may also increase P loss from agricultural soils, posing environmental impact. A long term experiment was conducted on a calcareous soil (meadow cinnamon) in Hebei Province, China, from 2003 to 2006 to investigate the effects of phosphate fertilizer and manure on the yield of Chinese cabbage, soil P accumulation, P sorption saturation, soluble P in runoff water, and P leaching. P fertilizer (P2O5) application at a rate of 360 kg ha^-1 or manure of 150 t ha^-1 significantly increased Chinese cabbage yield as compared to the unfertilized control. However, no significant yield response was found with excessive phosphate or manure application. Soil Olsen-P, soluble P, bioavailable P, the degree of phosphorus sorption saturation in top soil layer (0-20 cm), and soluble P in runoff water increased significantly with the increase of phosphate fertilizer and manure application rates, whereas the maximum phosphorus sorption capacity (Qm) decreased with the phosphate fertilizer and manure application rates. Soil Olsen-P and soluble P also increased significantly in the sub soil layer (20-40 cm) with the high P fertilizer and manure rates. It indicates that excessive P application over crop demand can lead to a high environmental risk owing to the enrichment of soil Olsen-P, soluble P, bioavailable P, and the degree of phosphorus sorption saturation in agricultural soils. 展开更多
关键词 phosphate fertilizer MANURE yield response P accumulation in soil environmental risk of P loss
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Modeling Patch Characteristics of Farmland Loss for Site Assessment in Urban Fringe of Beijing, China 被引量:3
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作者 LIU Xiaona ZHANG Weiwei +1 位作者 LI Hong SUN Danfeng 《Chinese Geographical Science》 SCIE CSCD 2013年第3期365-377,共13页
Farmland protection and delimitation in the urban fringe considers not only natural factors but also the spatial characters and site factors. Taking Daxing District, Beijing in China as a case study, this paper used l... Farmland protection and delimitation in the urban fringe considers not only natural factors but also the spatial characters and site factors. Taking Daxing District, Beijing in China as a case study, this paper used landscape ecology and power-law methods to ana- lyze and evaluate farmland loss during the period of 2004~2007 based on the interpretation results of SPOT5 remote sensing images in 2004 and 2007. At the patch level, we selected four landscape indices, namely patch size, shape index, the nearest neighbor distance between farmland and construction land (including residential land and other construction land), and cropping type, to evaluate the risk of farmland loss and establish a farmland site analysis indicator system. The results showed that patch size and shape index have a sig- nificant positive correlation with farmland loss, whereas the distance to construction land has a clear negative correlation with farmland loss. As regards cropping type, fallow farmland is much easier for non-agriculUlral use than cultivated farmland. The relative transition ratio among vegetable land, fallow farmland and cultivated farmland is 1 : 5.6 : 1. The patch size of lost farmland follows a power-law distribution, indicating that not only small parcels but also large parcels can be lost. Patch size less than 4 ha or more than 15 ha is in high loss risk, between 4 ha and 10 ha in medium loss risk, and larger than 10 ha and less than 15 ha in low risk. Farmland with a more regular shape has a higher likelihood of loss. Patch shape index less than 2.0 is in high loss risk, between 2.0 and 3.0 in medium loss risk, and larger than 3.0 in low risk. Construction land has a varying impact on farmland loss, the residential land effeeted distance is 1000 m, and that of the other construction land is 2000 m. This analysis showed the relationships between site factors and farmland loss, and the analysis framework can provide support and reference for farmland protection and delimitation of prime farmland in China. 展开更多
关键词 farmland loss loss risk site analysis logistic regression analysis power-law distribution
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Evolution of seismic risk management for insurance over the past 30 years 被引量:3
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作者 Haresh C.Shah Weimin Dong +1 位作者 Pane Stojanovski Alex Chen 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2018年第1期11-18,共8页
During the past 30 years, there has been spectacular growth in the use of risk analysis and risk management tools developed by engineers in the financial and insurance sectors. The insurance, the reinsurance, and the ... During the past 30 years, there has been spectacular growth in the use of risk analysis and risk management tools developed by engineers in the financial and insurance sectors. The insurance, the reinsurance, and the investment banking sectors have enthusiastically adopted loss estimation tools developed by engineers in developing their business strategies and for managing their financial risks. As a result, insurance/reinsurance strategy has evolved as a major risk mitigation tool in managing catastrophe risk at the individual, corporate, and government level. This is particularly true in developed countries such as US, Western Europe, and Japan. Unfortunately, it has not received the needed attention in developing countries, where such a strategy for risk management is most needed. Fortunately, in the last five years, there has been excellent focus in developing "Insur Tech" tools to address the much needed "Insurance for the Masses", especially for the Asian Markets. In the earlier years of catastrophe model development, risk analysts were mainly concerned with risk reduction options through engineering strategies, and relatively little attention was given to financial and economic strategies. Such state-of-affairs still exists in many developing countries. The new developments in the science and technologies of loss estimation due to natural catastrophes have made it possible for financial sectors to model their business strategies such as peril and geographic diversification, premium calculations, reserve strategies, reinsurance contracts, and other underwriting tools. These developments have not only changed the way in which financial sectors assess and manage their risks, but have also changed the domain of opportunities for engineers and scientists.This paper will address the issues related to developing insurance/reinsurance strategies to mitigate catastrophe risks and describe the role catastrophe risk insurance and reinsurance has played in managing financial risk due to natural catastrophes. Historical losses and the share of those losses covered by insurance will be presented. How such risk sharing can help the nation share the burden of losses between tax paying public, the "at risk" property owners, the insurers and the reinsurers will be discussed. The paper will summarize the tools that are used by the insurance and reinsurance companies for estimating their future losses due to catastrophic natural events. The paper will also show how the results of loss estimation technologies developed by engineers are communicated to the business flow of insurance/reinsurance companies. Finally, to make it possible to grow "Insurance for the Masses - IFM", the role played by parametric insurance products and Insur Tech tools will be discussed. 展开更多
关键词 catastrophe risk management loss estimation risk modeling insurance for the masses
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Assessing field vulnerability to phosphorus loss in Beijing agricultural area using Revised Field Phosphorus Ranking Scheme 被引量:7
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作者 LI Qi CHEN Li-ding +3 位作者 QI Xin ZHANG Xin-yu MA Yan FU Bo-jie 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2007年第8期977-985,共9页
Guanting Reservoir, one of the drinking water supply sources of Beijing, suffers from water eutrophication. It is mainly supplied by Guishui River. Thus, to investigate the reasons of phosphorus (P) loss and improve... Guanting Reservoir, one of the drinking water supply sources of Beijing, suffers from water eutrophication. It is mainly supplied by Guishui River. Thus, to investigate the reasons of phosphorus (P) loss and improve the P management strategies in Guishui River watershed are important for the safety of drinking water in this region. In this study, a Revised Field P Ranking Scheme (PRS) was developed to reflect the field vulnerability of P loss at the field scale based on the Field PRS. In this new scheme, six factors are included, and each one was assigned a relative weight and a determination method. The affecting factors were classified into transport factors and source factors, and, the standards of environmental quality on surface water and soil erosion classification and degradation of the China were used in this scheme. By the new scheme, thirty-four fields in the Guishui River were categorized as "low", "medium" or "high" potential for P loss into the runoff. The results showed that the P loss risks of orchard and vegetable fields were higher than that of corn and soybean fields. The source factors were the main factors to affect P loss from the study area. In the study area, controlling P input and improving P usage efficiency are critical to decrease P loss. Based on the results, it was suggested that more attention should be paid on the fields of vegetable and orchard since they have extremely high usage rate of P and high soil test of P. Compared with P surplus by field measurements, the Revised Field PRS was more suitable for reflecting the characteristics of fields, and had higher potential capacity to identify critical source areas of P loss than PRS. 展开更多
关键词 phosphorus loss risk assessment field scale revised phosphorus ranking scheme management strategy
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Estimator of Scale Parameter in a Subclass of the Exponential Family under Symmetric Entropy Loss 被引量:2
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作者 徐宝 王德辉 王瑞庭 《Northeastern Mathematical Journal》 CSCD 2008年第5期447-457,共11页
In this paper we investigate the estimator for the rth power of the scale parameter in a class of exponential family under symmetric entropy loss L(θ, δ) = v(θ/δ + δ/θ - 2). An exact form of the minimum ris... In this paper we investigate the estimator for the rth power of the scale parameter in a class of exponential family under symmetric entropy loss L(θ, δ) = v(θ/δ + δ/θ - 2). An exact form of the minimum risk equivariant estimator under symmetric entropy loss is given, and the minimaxity of the minimum risk equivariant estimator is proved. The results with regard to admissibility and inadmissibility of a class of linear estimators of the form cT(X) + d are given, where T(X) Gamma(v, θ). 展开更多
关键词 symmetric entropy loss minimum risk equivariant estimator Bayes estimator MINIMAXITY admissible estimator INADMISSIBILITY
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基于FloodArea模型的成都主城区内涝风险评估 被引量:1
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作者 邓国卫 孙俊 +2 位作者 徐沅鑫 徐金霞 彭骏 《气象科技》 2024年第2期265-276,共12页
本文以成都主城区为例,运用气象数据、地理信息数据、社会经济统计数据及内涝灾情资料,通过多种常用分布函数的对比,选出重现期降水估算的最优函数,采用Pilgrim&Cordery法推求研究区的小时雨型,然后结合改进的基于FloodArea内涝模型... 本文以成都主城区为例,运用气象数据、地理信息数据、社会经济统计数据及内涝灾情资料,通过多种常用分布函数的对比,选出重现期降水估算的最优函数,采用Pilgrim&Cordery法推求研究区的小时雨型,然后结合改进的基于FloodArea内涝模型,开展了24 h历时20、30、50、100 a一遇降水情景内涝模拟,并利用修订的内涝公路风险等级标准和财产损失曲线,探讨100 a一遇降水情景下内涝交通风险等级和居民室内财产损失风险。结果表明:①GEV(Generalized Extreme Value Distribution)分布函数是成都主城区重现期降水估算的最优函数;主城区24 h历时小时雨型呈双峰型,且峰值出现在降水过程前部。②基于FloodArea模型,通过对输入数据或参数的改进,能够较好模拟城市内涝空间分布;各降水情景模拟结果显示高新南区、高新西区、青羊区内涝淹没范围占比相较其他地区偏高。③24 h历时100 a一遇降水情景内涝可造成成都主城区86.1%公路长度占比出行困难,其中一级风险公路长度占比为10.5%,二、三级风险公路长度占比分别为27.5%、28.4%,成华区内涝公路风险最高。④24 h历时100 a一遇降水情景内涝可造成居民室内财产潜在损失约占主城区GDP(Gross Domestic Product)的0.8%,其中武侯区财产损失风险最大,潜在损失占其GDP的1.6%。 展开更多
关键词 城市内涝 风险评估 财产损失 FloodArea模型 成都
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Analysis on Landscape Ecological Risk of the Qinghai-Tibet Plateaus:A Case Study on Niyang River Basin 被引量:1
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作者 HE Xiaorong ZHONG Xianghao CHEN Xinwu 《Wuhan University Journal of Natural Sciences》 CAS 2006年第4期977-983,共7页
Taking Niyang River Basin as an example, applying with the indices of landscape pattern, the indices of ecological risk of ecosystems are calculated in this paper, which takes the value of ecological loss of main ecos... Taking Niyang River Basin as an example, applying with the indices of landscape pattern, the indices of ecological risk of ecosystems are calculated in this paper, which takes the value of ecological loss of main ecosystem as the evaluation standard and takes into account the impacts of probability or the velocity of main hazards and event of the ecosystem. And the grades of ecological risk are assessed. According to the results of assessment, the ecological risk grades of the basin are divided into five classes. From the first grade risk to the fifth grade risk, the values of regional risk indices gradually reduce. The first grade risk areas mainly distribute in Niyang river and its branches downstream and the surrounding areas of main towns. And the basin area of non-valley region and the headstream regions of the branches are the fifth grades risk areas. This evaluation results provide the basis to the regional sustainable development. 展开更多
关键词 the Qinghai-Tibet Plateau Niyang River Basin ecological risk indices of ecological risk the value of ecological loss DISASTER
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中国农田磷流失风险评价及其关键驱动因素 被引量:5
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作者 郑博福 刘海燕 +4 位作者 吴汉卿 吴之见 刘忠 朱锦奇 万炜 《农业工程学报》 EI CAS CSCD 北大核心 2024年第2期332-343,共12页
农田面源磷流失是农业面源污染的重要原因之一,识别流域内农田磷流失风险的关键源区及其影响因子是面源污染控制的重要手段。基于磷指数模型开展2000—2020年中国农田磷流失风险评估,选取土壤有效磷含量、磷肥施用量为源因子,土壤侵蚀... 农田面源磷流失是农业面源污染的重要原因之一,识别流域内农田磷流失风险的关键源区及其影响因子是面源污染控制的重要手段。基于磷指数模型开展2000—2020年中国农田磷流失风险评估,选取土壤有效磷含量、磷肥施用量为源因子,土壤侵蚀模数、年径流深、农田和水体间归一化距离指数为迁移因子,结合GIS技术评估了中国农田磷流失的关键源区;在此基础上,利用随机森林法分析影响中国农田磷流失的关键因子,并通过结构方程模型揭示了农田磷流失风险指数与各因子的关系。结果表明:1)2000—2020年中国农田的磷流失的低、中、高、极高风险面积分别占农田总面积的43.8%、40.5%、13.4%、2.4%。2)中国农田磷流失在2000、2005、2010、2015、2020年高风险和极高风险总面积的年平均占比从大到小依次为:淮河流域、长江流域、珠江流域、东南诸河流域、松辽河流域、西南诸河流域、黄河流域、内陆河流域、海河流域。3)影响农田磷流失风险的关键源因子和迁移因子分别为土壤有效磷含量和归一化距离指数,其重要性特征值分别为129.53和65.12,土壤有效磷含量是农田磷流失最主要影响因子。4)磷流失风险指数与源因子指数、迁移因子指数呈极显著正相关,选取的14个指标对磷指数的解释度达0.62,其中源因子和迁移因子对磷指数的贡献率分别为0.77、0.19(P <0.001)。研究结果可为中国农田磷流失风险评估提供科学参考,对中国农业面源污染的宏观防控及战略决策具有重要意义。 展开更多
关键词 农田 面源污染 磷指数模型 磷流失 风险评价 关键因子 随机森林 结构方程模型
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A Note on Quantitative Definition of Risk
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作者 李力 赵联文 杨宁 《Journal of Southwest Jiaotong University(English Edition)》 2004年第1期91-93,共3页
Risk analysis has become more and more important in practical application, but there has not been a widely accepted frame work and model for the research. Motivated by factor analysis method and Kaplan-Garrick's q... Risk analysis has become more and more important in practical application, but there has not been a widely accepted frame work and model for the research. Motivated by factor analysis method and Kaplan-Garrick's quantitative definition of risk, a general risk model was established based on analyzing risk situations and employing information system and evidence theory, and Kaplan-Garrick's result was improved to introduce a frame word for analyzing and managing risk. 展开更多
关键词 risk Uncertainty PROBABILITY DECISION loss Information system
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骨科患者术中下肢深静脉血栓风险增高的血流变化及影响因素 被引量:1
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作者 方敏 高兴莲 +3 位作者 王曾妍 柯稳 肖潇 梁元元 《护理学杂志》 CSCD 北大核心 2024年第10期64-67,共4页
目的探讨骨科患者术中下肢深静脉血栓(DVT)风险增高的血流变化特点并分析其影响因素,为手术室护理干预提供临床指导。方法选取151例骨科择期手术患者为研究对象,术中使用多普勒超声诊断仪观察下肢血流改变特征,并收集患者基本资料、手... 目的探讨骨科患者术中下肢深静脉血栓(DVT)风险增高的血流变化特点并分析其影响因素,为手术室护理干预提供临床指导。方法选取151例骨科择期手术患者为研究对象,术中使用多普勒超声诊断仪观察下肢血流改变特征,并收集患者基本资料、手术相关资料、术前实验室检查指标等,患者手术结束24 h内采血行D-二聚体凝血功能检测。结果D-二聚体检测结果显示,DVT高风险患者70例(46.36%),低风险81例(53.64%)。手术结束后DVT高风险患者下肢平均血流速度、血管内径显著低于或小于低风险患者(均P<0.05)。logistic回归分析显示,手术时间>120 min、凝血酶原时间(PT)>13.1 s、术中发生低体温和术中失血量>100 mL是骨科患者术中DVT风险增高的独立危险因素(均P<0.05)。结论骨科手术患者术中DVT发生风险较高,存在明显血流动力学改变。手术室护理人员需针对性地开展手术效率管理、术中低体温监测和预防、维持术中血容量稳定,有效降低骨科手术患者术中DVT发生风险。 展开更多
关键词 骨科手术 术中 下肢深静脉血栓 血流动力学 低体温 术中失血量 风险管理 手术室护理
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