Three-dimensional pseudo-dynamic reliability analysis of seismic shield tunnel faces combined with sparse polynomial chaos expansion

To address the seismic face stability challenges encountered in urban and subsea tunnel construction,an efficient probabilistic analysis framework for shield tunnel faces under seismic conditions is proposed.Based on the upper-bound theory of limit analysis,an improved three-dimensional discrete deterministic mechanism,accounting for the heterogeneous nature of soil media,is formulated to evaluate seismic face stability.The metamodel of failure probabilistic assessments for seismic tunnel faces is constructed by integrating the sparse polynomial chaos expansion method(SPCE)with the modified pseudo-dynamic approach(MPD).The improved deterministic model is validated by comparing with published literature and numerical simulations results,and the SPCE-MPD metamodel is examined with the traditional MCS method.Based on the SPCE-MPD metamodels,the seismic effects on face failure probability and reliability index are presented and the global sensitivity analysis(GSA)is involved to reflect the influence order of seismic action parameters.Finally,the proposed approach is tested to be effective by a engineering case of the Chengdu outer ring tunnel.The results show that higher uncertainty of seismic response on face stability should be noticed in areas with intense earthquakes and variation of seismic wave velocity has the most profound influence on tunnel face stability.

卫冕2006 四个婚礼和一个葬礼——2005/06赛季五大联赛总结定评

2005/06赛季的欧洲联赛或许很好找出一个"关键词",那就是:卫冕。自1963/64赛季德甲创立迄今,还从未出现过五大卫冕满贯的盛况,人人皆知打江山难、守江山更难的道理,今年尤文图斯、巴萨、切尔西、里昂和拜仁居然同时捍卫了去岁获得的奖杯,这是巧合更是奇迹。本赛季欧洲联赛的"场内秩序"也许是受了世界杯年的"干扰",绝大多数时候显得波澜不惊、个体表演远比整体表现精彩,除了五大联赛之外,埃因霍温、凯尔特人也都卫冕成功,在经历了2003/04赛季冠军联赛出现"海啸级"的冷门刺激之后——欧罗巴赛场出奇的安静和平淡。

学问贵乎疑定评

本期《学问》郑重地向读者推荐王仁富先生《现藏日本皇宫的唐鸿胪井刻石探讨》、梁琴的《心系刻石祭崔新——记中国唐鸿胪井刻石研究学者王仁富教授》和拙文《唐鸿胪井刻石研究的两点质疑》。旅顺黄金山唐鸿胪井刻石是唐鸿胪卿崔訢出使渤海王国返回时留下的珍贵文物。但是在对刻文"鸿胪卿崔忻井两口永为记验"断句时,由于明代《辽东志》编撰者的疏忽,错将"忻"字上断,结果把《旧唐书》上正确的"崔訢"误为"崔忻",造成400年之久的史误。崔訢名字之误,由来已久。《旧唐书》上正确的"崔訢"被搁置一旁,错误的"崔忻"

工程认证背景下实践课程成绩评定方法与应用

随着非标准化考试等教学改革的推进,课程成绩评定成为高校实践类课程的重要考核方式。然而,由于缺乏客观定量的评价方法,主观性考核方式在认定考生成绩时存在较大不确定性。如何有效降低主观评判的随意性和不确定性成为课程成绩核定亟须解决的问题。研究提出基于师生协作的综合成绩评估方法,采用动态权重法综合学生打分和教师打分,形成更加合理的综合成绩分布,并以本科必修课程“环境规划与管理”期末成绩评定为例开展案例研究。结果表明,合理应用学生打分能够改善学生成绩分布,但要注意规避学生打分可能存在的均一化倾向和简单等权评分带来的成绩偏态分布问题。研究成果以期为大学实训类课程成绩评定提供一种新的方法。

拨开历史的迷雾——近年来张资平研究综述

张资平是20世纪20年代有影响的作家,但对他的研究一直处于不景气的状态。造成这种状态的原因主要是观念上囿于历史定评,研究方法单一。文章探讨了张资平研究的现状,认为应该以多样化的方法,尽力还给人们一个真实的张资平。

Screening of Drought Stress Indicators and Analysis of Drought Resistance in Cultivated Rice Germplasm Resources in Guangxi

This study aimed to screen drought stress indicators and analyze the drought resistance in 105 cultivated rice germplasm resources in Guangxi Zhuang Autonomous Region under drought stress in the whole growth period based on D value of seven morphological traits including panicle neck thickness,effective panicle number per plant,1 000-grain weight,filled grain number per panicle,total grain number,seed setting rate and yield per plant.According to the results,under drought stress,yield per plant exhibited significant positive correlation with panicle neck thickness and exhibited extremely significant positive correlation with other five morphological traits.Based on the identification and evaluation of comprehensive drought-resistance index D value,seven highly drought-resistant cultivated rice varieties were screened,accounting for 6.67％.Upland rice germplasm resources in Guangxi Zhuang Autonomous Region possess strong drought-resistance capacity,which could be used to screen highly drought-resistant rice germplasm materials.This study provided material basis and theoretical reference for breeding drought resistant rice cultivars in Guangxi Zhuang Autonomous Region.

On the Identification and Evaluation of Salt Tolerance of Peanut Germplasm

For screening out salt tolerance germplasm and providing materials for ge- netic research of peanut, based on the indexes including relative germination poten- tial, relative germination rate, relative germination index and salt-injury rate, 128 peanut germplasms were selected for salt-tolerant identification and estimation under 2.5% NaCI. We found significant but various depressing levels of germination rate under salt stress among different germplasms, and only 5% of 128 germplasms were highly resistant to salinity. We also found that the relative germination index was a useful evaluation index for salt tolerance besides salt damage rate and rela- tive germination rate. After all, we comprehensively screened out 7 materials （JS011, JS024, JS125, JS491, JS523, JS524 and JS525） as salt tolerance germplasms for further research. Key

Model and method of permeability evaluation based on mud invasion effects

The evaluation of permeability in reservoir assessment is a complex problem. Thus, it is difficult to perform direct evaluation permeability with conventional well-logging methods. Considering that reservoir permeability significantly affects mud invasion during drilling, we derive a mathematical model to assess the reservoir permeability based on mud invasion. A numerical model is first used to simulate the process of mud invasion and mud cake growth. Then, based on Darcy＇s law, an approximation is derived to associate the depth of mud invasion with reservoir permeability. A mathematical model is constructed to evaluate the reservoir permeability as a function of the mud invasion depth in time-lapse logging. Sensitivity analyses of the reservoir porosity, permeability, and water saturation are performed, and the results suggest that the proposed model and method are well suited for oil layers or oil-water layers of low porosity and low permeability. Numerical simulations using field logging and coring data suggest that the evaluated and assumed permeability data agree, validating the proposed model and method.

ON INFORMATION THEORY METHOD FOR RELIABILITY ASSESSMENT OF SYSTEMS CONSISTING OF DIFFERENT SUCCESS FAILURE MODEL UNITS

Using the characteristic of addition of information quantity and the principle of equivalence of information quantity, this paper derives the general conversion formulae of the formation theory method conversion (synthesis) on the systems consisting of different success failure model units. According to the fundamental method of the unit reliability assessment, the general models of system reliability approximate lower limits are given. Finally, this paper analyses the application of the assessment method by examples, the assessment results are neither conservative nor radical and very satisfactory. The assessment method can be popularized to the systems which have fixed reliability structural models.

NOVEL APPROACH TO LOCATOR LAYOUT OPTIMIZATION BASED ON GENETIC ALGORITHM

Proper fixture design is crucial to obtain the better product quality according to the design specification during the workpiece fabrication. Locator layout planning is one of the most important tasks in the fixture design process. However, the design of a fixture relies heavily on the designerts expertise and experience up to now. Therefore, a new approach to loeator layout determination for workpieces with arbitrary complex surfaces is pro- posed for the first time. Firstly, based on the fuzzy judgment method, the proper locating reference and locator - numbers are determined with consideration of surface type, surface area and position tolerance. Secondly, the lo- cator positions are optimized by genetic algorithm（GA）. Finally, a typical example shows that the approach is su- perior to the experiential method and can improve positioning accuracy effectively.

Application of uncertain type of AHP to condition assessment of cable-stayed bridges

In order to guarantee the safety service and life-span of long-span cable-stayed bridges, the uncertain type of analytic hierarchy process （AHP） method is adopted to access the bridge condition. The correlative theory and applied objects of uncertain type of AHP are introduced, and then the optimal transitive matrix method is chosen to calculate the interval number judgment matrix, which makes the weights of indices more reliable and accurate. Finally, with Harbin Songhua River Cable-Stayed Bridge as an example, an index system and an assessment model are proposed for the condition assessment of this bridge, and by using uncertain type of AHP, the weights of assessment indices are fixed and the final assessment results of the bridge are calculated, which proves the feasibility and practicability of this method. The application of this assessment method can provide the scientific basis for maintenance and management of long-span cable-stayed bridges.

长啸满江红 千秋朝天阙——对岳飞的历史评价再认识

中国南宋名将岳飞,是位已有860多年历史定评的民族英雄。 然而近来,海外华人社会针对有人提出岳飞“是否愚忠”的问题,派生出“贬岳”与“挺岳”双方,掀起的一场迄今两个多月大争论,触动了众多炎黄子孙的民族神经。接着而起的是,中国大陆许多人以有一种高中历史教学参考资料中对岳飞、文天祥等“不称之为民族英雄”的问题为发端,展开的又一场大讨论,牵动了广大华夏儿女的民族感情。

Uncertainty Evaluation of Preparation of Organophosphorus Pesticide Mixed Standard Solution

The uncertainty of standard solution plays an important role in detection of pesticide residues. It may affect the accuracy of detection results. In this study, the 14 organophosphorus pesticides mixed standard solution was used as the material to analyze all the influencing factors for the preparation of mixed standard solution with uncertainty as the only judging index. The preparation uncertainty of mixed standard solution was calculated with the top-down calculation method. In the end, the expanded uncertainty was presented. The results showed that the preparation of mixed standard solution from stock solution with precise pipettes had a relatively low uncertainty.

《沧桑》连续7年被评为山西省一级期刊

本刊讯《沧桑》在2006年度山西省期刊质量评估中,再次被评为山西省一级期刊。至此《,沧桑》已连续7年(2000-2006)获此殊荣。

The Study of Using Near-infrared Diffuse Reflectance Spectroscopy Rapid Identify Wheat Drought Resistance-Ⅱ

[Objective] The aim was to build an evaluation method rapidly identifying wheat drought tolerance with near infrared diffuse reflectance spectroscopy. [Method] In the research, 36 wheat varieties in 2007-2009 were chosen and drought-tolerance degrees of wheat were graded and identified according to Winter-wheat Drought Tol- erance Evaluation Technical Standards （GB/T 21127-2007）, and harvest wheat grains underwent spectrum collection, with a full-spectrum analyzer, to establish a database. [Result] Based on qualitative analysis and full-spectrum correlation research, the coef- ficient of determination （RSQ） and cross-validation coefficient of determination （1-VR） were concluded at 0.697 5 and 0.600 2, showing near-infrared diffuse reflectance spectroscopy is of significant differences among wheat varieties and of significant or extremely significant correlation with drought-tolerance indices. [Conclusion] The re- search indicates that to evaluate drought-tolerance of wheat with near-infrared diffuse reflectance spectroscopy is a rapid and feasible way, which is simple, convenient without damages on grains, and of practical values for construction wheat drought-tol- erance evaluation index system and identification of breeding materials.

Bus transit travel time reliability evaluation based on automatic vehicle location data

In order to provide important parameters for schedule designing, decision-making bases for transit operation management and references for passengers traveling by bus, bus transit travel time reliability is analyzed and evaluated based on automatic vehicle location （AVL） data. Based on the statistical analysis of the bus transit travel time, six indices including the coefficient of variance, the width of travel time distribution, the mean commercial speed, the congestion frequency, the planning time index and the buffer time index are proposed. Moreover, a framework for evaluating bus transit travel time reliability is constructed. Finally, a case study on a certain bus route in Suzhou is conducted. Results show that the proposed evaluation index system is simple and intuitive, and it can effectively reflect the efficiency and stability of bus operations. And a distinguishing feature of bus transit travel time reliability is the temporal pattern. It varies across different time periods.

Remote Sensing of Ecosystem Services:An Opportunity for Spatially Explicit Assessment

Ecosystem service is an emerging concept that grows to be a hot research area in ecology.Spatially explicit ecosystem service values are important for ecosystem service management.However,it is difficult to quantify ecosystem services.Remote sensing provides images covering Earth surface,which by nature are spatially explicit.Thus,remote sensing can be useful for quantitative assessment of ecosystem services.This paper reviews spatially explicit ecosystem service studies conducted in ecology and remote sensing in order to find out how remote sensing can be used for ecosystem service assessment.Several important areas considered include land cover,biodiversity,and carbon,water and soil related ecosystem services.We found that remote sensing can be used for ecosystem service assessment in three different ways:direct monitoring,indirect monitoring,and combined use with ecosystem models.Some plant and water related ecosystem services can be directly monitored by remote sensing.Most commonly,remote sensing can provide surrogate information on plant and soil characteristics in an ecosystem.For ecosystem process related ecosystem services,remote sensing can help measure spatially explicit parameters.We conclude that acquiring good in-situ measurements and selecting appropriate remote sensor data in terms of resolution are critical for accurate assessment of ecosystem services.

Short-Term Influence of Herbicide Quinclorac on Enzyme Activities in Flooded Paddy Soils

The influence of quinclorac (3,7-dichloroquinoline-8-carboxylic acid) on enzyme activities in flooded paddy soils was assessed under laboratory conditions. The enzymes differed markedly in their response to quinclorac. Quinclorac inhibited proteinase, hydrogen peroxidase, phosphorylase, and urease activities.The higher the concentration of quinclorac applied, the more significant the inhibition to these observed activities with a longer time required to recover to the level of the control. However, soils supplemented with quinclorac were nonpersistent for proteinase, phosphorylase and urease as opposed to soils without quinclorac. Dehydrogenase activity was also sensitive to quinclorac. Three soil samples with concentrations of quinclorac higher than 1 μg g-1 soil declined to less than 20% of that in the control. However, the highest dehydrogenase activity (up to 3.28-fold) was detected in soils with 2 μg g-1 soil quinclorac on the 25th day after treatment. Quinclorac had a relatively mild effect on saccharase activity at the concentrations used in this experiment and a stimulatory one on soil respiration when added to soil at normal field concentrations.Nonetheless it was inhibited at higher concentrations in paddy soils. Quinclorac is still relatively safe to the soil ecosystem when applied at a normal concentration (0.67 μg g-1 dried soil) but may have some effects on soil enzymes at higher concentrations.

Contrast-enhanced ultrasonography assessment of gastric cancer response to neoadjuvant chemotherapy

AIM:To quantitatively assess the ability of double contrast-enhanced ultrasound(DCUS) to detect tumor early response to pre-operative chemotherapy.METHODS:Forty-three patients with gastric cancer treated with neoadjuvant chemotherapy followed by curative resection between September 2011 and February 2012 were analyzed.Pre-operative chemotherapy regimens of fluorouracil + oxaliplatin or S-1 + oxaliplatin were administered in 2-4 cycles over 6-12 wk periods.All patients underwent contrast-enhanced computed tomography(CT) scan and DCUS before and after two courses of pre-operative chemotherapy.The therapeutic response was assessed by CT using the response evaluation criteria in solid tumors(RECIST 1.1) criteria.Tumor area was assessed by DCUS as enhanced appearance of gastric carcinoma due to tumor vascularity during the contrast phase as compared to the normal gastric wall.Histopathologic analysis was carried out according to the Mandard tumor regression grade criteria and used as the reference standard.Receiver operating characteristic(ROC) analysis was used to evaluate the efficacy of DCUS parameters in differentiating histopathological responders from non-responders.RESULTS:The study population consisted of 32 men and 11 women,with mean age of 59.7 ± 11.4 years.Neither age,sex,histologic type,tumor site,T stage,nor N stage was associated with pathological response.The responders had significantly smaller mean tumor size than the non-responders(15.7 ± 7.4 cm vs 33.3 ± 14.1 cm,P < 0.01).According to Mandard's criteria,27 patients were classified as responders,with 11(40.7%) showing decreased tumor size by DCUS.In contrast,only three(18.8%) of the 16 non-responders showed decreased tumor size by DCUS(P < 0.01).The area under the ROC curve was 0.64,with a 95%CI of 0.46-0.81.The effects of several cut-off points on diagnostic parameters were calculated in the ROC curve analysis.By maximizing Youden's index(sensitivity + specificity-1),the best cut-off point for distinguishing responders from non-responders was determined,which had optimal sensitivity of 62.9% and specificity of 56.3%.Using this cut-off point,the positive and negative predictive values of DCUS for distinguishing responders from non-responders were 70.8% and 47.4%,respectively.The overall accuracy of DCUS for therapeutic response assessment was 60.5%,slightly higher than the 53.5% for CT response assessment with RECIST criteria(P = 0.663).Although the advantage was not statistically significant,likely due to the small number of cases assessed.DCUS was able to identify decreased perfusion in responders who showed no morphological change by CT imaging,which can be occluded by such treatment effects as fibrosis and edema.CONCLUSION:DCUS may represent an innovative tool for more accurately predicting histopathological response to neoadjuvant chemotherapy before surgical resection in patients with locally-advanced gastric cancer.

Three-dimensional analysis of slopes reinforced with piles

Based on the upper bound of limit analysis, the plane-strain analysis of the slopes reinforced with a row of piles to the 3D case was extended. A 3D rotational failure mechanism was adopted to yield the upper bound of the factor of safety. Parametric studies were carried out to explore the end effects of the slope failures and the effects of the pile location and diameter on the safety of the reinforced slopes. The results demonstrate that the end effects nearly have no effects on the most suitable location of the installed piles but have significant influence on the safety of the slopes. For a slope constrained to a narrow width, the slope becomes more stable owing to the contribution of the end effects. When the slope is reinforced with a row of piles in small space between piles, the effects of group piles are significant for evaluating the safety of slopes. The presented method is more appropriate for assessing the stability of slopes reinforced with piles and can be also utilized in the design of plies stabilizing the unstable slopes.