储气库注采井失效模式与风险评估技术

阐述了国内外关于储气库注采井失效模式概况及主要的几种风险致因类型,讨论了注采井失效的主要风险类别的原因与类型,指出了目前风险分析关键方法的主要技术瓶颈及技术要点并结合相关标准的差异性和侧重点进行了论述。概述了井筒完整性风险评估流程及具体实施技术路线,指出基于大数据分析的失效类型统计与智能化风险识别技术已成为风险评估领域的研究热点。

Investigation and Risk Assessment of Alien Invasive Plants in Riparian Zone of Dongjiang River

[Objective] The aim was to conduct investigation and risk assessment of the alien invasive plants in riparian zone of Dongjiang River.[Method] The field survey was carried out by the combination methods of sampling plots investigation and route survey,and the whole Dongjiang River was covered.52 sampling points were set in the main streams,and 87 sampling points in tributaries streams,624 quadrats were set in total;multi-index comprehensive evaluation method was adopted for the risk assessment with 6 first-level indexes and 25 second-level indexes.[Result] Through the investigation on the riparian zone of Dongjiang River for 2 years,51 species of alien invasive plants were found,belonging to 17 families and 38 genera.The risk level assessment results of these 51 species showed that 18 species,such as Ageratum conyzoides,belonged to high-level risk with over 60 points;26 species,such as Chenopodium ambrosioides,were between 30 and 60 points which belonged to middle-level risk;7 species,such as Paspalum dilatatum,with less than 30 points belonged to low-level risk.[Conclusion] Basic data on the protection,water environmental management and functional zoning of riparian zone of Dongjiang River were provided.

Forecast Method of Multimode System for Debris Flow Risk Assessment in Qingping Town,Sichuan Province,China

The Wenchuan Earthquake of May 12,2008 triggered large numbers of geo-hazards.The heavy rain on 13 August 2010 triggered debris flows with total volume of more than 6 million cubic meters and the debris flows destroyed 500 houses and infrastructure built after the Wenchuan Earthquake.The study area Qingping Town was located in the northwestern part of the Sichuan Basin of China,which needs the second reconstructions and the critical evaluation of debris flow.This study takes basin as the study unit and defines collapse,landslide and debris flow hazard as a geo-hazard system.A multimode system composed of principal series system and secondary parallel system were established to evaluate the hazard grade of debris flow in 138 drainage basins of Qingping Town.The evaluation result shows that 30.43% of study basins(42 basins) and 24.58% of study area,are in extremely high or high hazard grades,and both percentage of basin quantity and percentage of area in different hazard grades decrease with the increase of hazard grade.According to the geo-hazard data from the interpretation of unmanned plane image with a 0.5-m resolution and field investigation after the Wenchuan Earthquake and 8.13 Big Debris Flow,the ratio of landslides and collapses increased after the Wenchuan Earthquake and the ratios of extremely high or high hazard grades were more than moderate or low hazard grades obviously.23 geo-hazards after8.13 Big Debris Flow in Qingping town region all occurred in basins with extremely high or high hazard grades,and 9 debris flows were in basins with extremely high hazard grade.The model of multimode system for critical evaluation could forecast not only the collapse and landslide but also the debris flow precisely when the basin was taken as the study unit.

Coronary heart disease incidence and competing risks： an important issue

The estimation of lifetime morbid events is not a rare presentation of relatively old and of more recent epidemi- ological investigations, accompanied by evaluating rates, risks and predictors （more in general determinants or risk factors）. However, when the follow-up period is very long and Kaplan-Meier survival curves are adopted, or Kaplan- Meier-based more complex models such as Cox＇s analysis are used, clinical （or epidemiological） reality may well be distorted since by these survival methods risks tend to be overestimated, whereas survival tends to be reduced.

Risk Assessment of Highways Affected by Debris Flows in Wenchuan Earthquake Area

Since the Wenchuan earthquake in China on May 12th, 2008, highways in earthquake-affected areas have been frequently interrupted by debris flows. We analyzed the hazard effect modes and damage processes along highways and developed three key indexes, scale of debris flows, deposits on highways and river blockage, to describe quantitatively the highway disasters. By combining the empirical methods and the actual terrain conditions, we proposed new methods to determine the value of hazard indexes. In addition, we used the economic value and resistance of highway as vulnerability assessment indexes, then determined the specific subindexes for the subgrade, bridges and culverts, and developed a way for the quantified vulnerability zoning. Moreover, we proposed the assessment and mapping methods for highway risk. The risk is described into 5 grades： extremely low risk, low risk, middle risk, high risk and extremely high risk. We applied these methods in a case study carried out on provincial highway S3o3 from Yingxiu Town to Wolong Town, in Wenchuan County. Analysis of debris flow risk for the whole highway, showed that the total length of highway in extremely low risk area was 28.26 km, 4.83 km in low risk area, 8.0 km in middle risk area, 3.65 km in high risk area, and 3.06 km in extremely high risk area. The assessment results are consistent with the field survey data which reflected the disaster situation. This risk method can be used objectively to evaluate the debris-flow risk along highways, and is useful for highway reconstruction in mountainous areas suffering from active debris flows.

Risk Assessment of Nitrogen Discharge from a Coastal Watershed

Probabilistic risk assessment （PRA） uses probability theory to quantify the probability of occurrence of an event. In this study, PRA was conducted for the discharge of excess nitrogen （N） from an agricultural （Jiulong River） watershed in Southeast China. Using fault tree analysis, a type of PRA, the probability of occurrence of excess N discharge into the river during a runoff event was evaluated both qualitatively and quantitatively. Land use maps, soil maps, fertilizer use records, and expert opinions were used to determine probabilities of individual events within the fault tree and to calculate the overall probability of excess N discharge during a runoff event. Qualitative analysis showed that the risk of excess N discharge was mainly related to crop and livestock practices in the watershed. Proper management of tillage, fertilizer, and manure was necessary to control N releases. Quantitative assessment results indicated that alternative practices including reduction of fertilization, installation of vegetative strip buffer around the pig farms, and installation of more riparian buffers along the Jiulong River could reduce the likelihood of N discharge through runoff.

Debris Flows Risk Analysis and Direct Loss Estimation:the Case Study of Valtellina di Tirano,Italy

andslide risk analysis is one of the primary studies providing essential instructions to the subsequent risk management process. The quantification of tangible and intangible potential losses is a critical step because it provides essential data upon which judgments can be made and policy can be formulated. This study aims at quantifying direct economic losses from debris flows at a medium scale in the study area in Italian Central Alps. Available hazard maps were the main inputs of this study. These maps were overlaid with information concerning elements at risk and their economic value. Then, a combination of both market and construction values was used to obtain estimates of future economic losses. As a result, two direct economic risk maps were prepared together with risk curves, useful to summarize expected monetary damage against the respective hazard probability. Afterwards, a qualitative risk map derived using a risk matrix officially provided by the set of laws issued by the regional government, was prepared. The results delimit areas of high economic as well as strategic importance which might be affected by debris flows in the future. Aside from limitations and inaccuracies inherently included in risk analysis process, identification of high risk areas allows local authorities to focus their attention on the “hot-spots”, where important consequences may arise and local （large） scale analysis needs to be performed with more precise cost-effectiveness ratio. The risk maps can be also used by the local authorities to increase population’s adaptive capacity in the disaster prevention process.

Call Warrants Impact on Underlying Stocks： The Taiwan Experience

On the basis of the price, volume and volatility of underlying stocks, this article empirically investigates the impact of 273 Taiwan call warrants on underlying stocks. Discussions by the market risk, depth, tightness and liquidity, changes on underlying stocks due to warrants issuance, are investigated. In this study, the CAPM is applied for evaluating the market risk, the Kyle model for the market depth, the averaged best five bid-ask spread for the market tightness and the averaged turnover rate for the market liquidity. The empirical results indicate that the most significant influence is the market liquidity, the market tightness next; the market risk and market depth are non-significant.

Risk assessments of debris flow based on improved analytic hierarchy process and efficacy coefficient method

In order to evaluate the danger of debris flow properly, eight factors were selected as the risk assess- ment indexes of the debris flow, namely the vertical slope, valley relative difference, hillside slope, area of ba- sin, loose solid material reserves, the path length of sediment supply probability, silting and scouring derrieking and vegetation coverage. The improved Analytic Hierarchy Process （ AHP ） method was used to obtain the weights of the factors; and the efficacy coefficient method was adopted to evaluate the risks of six typical debris flow gullies. According to the research, the improved AHP method not only avoids the subjectivity in the indi- vidual factor valuation by comparing two factors of each layer, but also makes the subsequent consistency check unnecessary.

Assessment of Soil Erosion Risk in Albania

Albania results are a country with high quantitative level of soil erosion in Europe and elsewhere based on different studies. The amount of soil eroded from the surface water erosion is from 20-40 t/ha/year and in extreme cases results up to 100 t/ha/year from the deepest erosion. This preliminary study will identify the more specific places in order to do more details analyses in the future to take protection measures in highly sensitive places with high erosion risk. This will be a quantitative assessment of places with different level of erosion risks. Further on these results will be generalized at the level of main water basins of Albania. The following main elements of soil erosion assessment are evaluated in this study which include the land cover, slope and density of the hydrologic net.

Advantages and Disadvantages of Quantitative and Qualitative Information Risk Approaches

Due to rapidly development of information systems, risk and security issues have increased and became a phenomenon that concerns every organization, without considering the size of it. To achieve desired results, managers have to implement methods of evaluating and mitigating risk as part of a process well elaborated. Security risk management helps managers to better control the business practices and improve the business process. An effective risk management process is based on a successful IT security program. This doesn＇t mean that the main goal of an organization＇s risk management process is to protect its IT assets, but to protect the organization and its ability to perform their missions. During this process, managers have to take into consideration risks that can affect the organization and apply the most suitable measures to minimize their impact. The most important task is choosing the best suited method for analyzing the existing risk properly. Several methods have been developed, being classified in quantitative and qualitative approaches of evaluating risk. The purpose of this paper is to present the advantages and disadvantages of each approach taking current needs and opportunities into consideration.

Quantitative Assessment and Spatial Characteristics of Agricultural Drought Risk in the Jinghe Watershed, Northwestern China

Though drought is a recurrent phenomenon in the Jinghe watershed, very little attention has been paid to drought mitigation and preparedness. This article presents a method for the spatial assessment of agricultural drought risk in the Jinghe watershed of western China at a 1-km grid scale. A conceptual framework, which emphasizes the combined roles of hazard and vulnerability in defining risk, is used. The Z index method in a GIS environment is used to map the spatial extent of drought hazards. The key social and physical factors that define agricultural drought in the context of the Jinghe watershed are indentified and corresponding thematic maps are prepared. Risk is calculated by the integration of hazard and vulnerability. Results show that the risk gradient follows a north-south and west-east tendency and that agricultural droughts pose the highest risk to northern and northwestern sections of the Jinghe watershed.

Evaluation of commutation failure risk in single-or multi-infeed LCC-HVDC systems based on equivalent-fault method

In single-or multi-infeed line-commutated converter-based high-voltage direct current(LCC-HVDC) systems, commutation failure(CF) induced by alternating current(AC) faults may lead to serious consequences. Considering the randomness of fault occurrences, an accurate evaluation of the CF risk(CFR) from the system point of view becomes necessary in power system planning and operation. This paper first provides a definition of the CF severity(CFS) index corresponding to an AC fault. Then,on the basis of electromagnetic transient(EMT) simulation, an approach to calculate the CFS index considering the randomness of fault-occurrence time is presented. A novel equivalent-fault method is further put forward to make the EMT simulation scalable to calculate the CFS index in terms of a fault occurring in a large-scale receiving-end grid. Thereafter, the CFR index is introduced, which is defined as the sum of the products of the CFS index of each AC fault and the corresponding fault rate.Finally, the proposed method is verified on the modified IEEE 9-bus and modified IEEE 39-bus systems using PSCAD/EMTDC.