城市轨道交通全断面岩石掘进机的机型分析比选

以岩石地层为主的城市轨道交通修建过程中,为避免传统钻爆法爆破施工造成的粉尘、废气、噪音及振动等污染,并提高施工技术水平,应研究采用全断面岩石掘进机进行施工。全断面岩石掘进机分为敞开式和护盾式两类,其中护盾式又分为单护盾、双护盾等机型。主要从地质适应性、各种机型自身特点等方面出发,对全断面岩石掘进机各种机型进行了分析比选。

几种竹材径向剖篾机型的分析比较

通过选用几种不同机型的竹材径向剖篾机,对竹材的不同切削形式、不同刀头结构,分步与同步剖篾方式,以及剖篾效率与竹篾质量等多方面进行分析比较,认为刨切式多刀分步径向剖篾机具有结构合理、剖篾效率高、径向竹篾厚度精度高、表面粗糙度小的优点,具有较好的推广应用前景。

煮茧机机型浅析

以“煮茧基础理论浅析”为基础,对现有机型的三大过程进行分析,剖析各类机型的优缺点,阐述了真空渗透和触蒸、汤蒸相结合的优越性,以及V型煮茧机如何保护外层丝胶等,目的是探讨一种新型煮茧机的设计。

Application of the Sub-Model Method in the Engine Strength Analysis

On the basis of introducing the fundamental theory and the basic analysis steps of the sub model method, the strength of the new engine complex assembly structure was analyzed according to the properties of the engine structures, some of the key parts of the engine were analyzed with refined mesh by sub model method and the error of the FEM solution was estimated by the extrapolation method. The example showed that the sub model can not only analyze the comlex structures without the restriction of the software and hardware of the computers, but get the more precise analysis result also. This method is more suitable for the strength analysis of the complex assembly structure.

昌马旧总干龙腾电站水轮机选型设计

水轮机作为电站的最重要部件之一,实现了水流由动能到电能的转换,选型的好坏直接关系到水电站的实际运行参数能否与水轮机的主要性能指标参数相匹配,关系到电站能否充分利用水能资源达到最佳的经济效益。本文结合昌马旧总干龙腾电站实际,借助水轮机型谱模型转轮综合特性曲线图分析,进行小型水电站水轮机选择设计。

北京首都国际机场停机位资源研究

航班运行量和机型的变化趋势对机场的停机坪使用率和运行效率起到至关重要的作用。笔者对北京首都国际机场（以下简称首都机场）停机位资源持续紧张的状况及原因进行分析,并运用统计学理论工具对2010—2015年首都机场停机位运行数据进行分析,对重点机型的运行量和种类变化进行趋势预测研究,分析未来一段时间内停机位使用状况和趋势。

情报研究方法在战略决策中的应用

情报研究作为战略决策的一个重要工作环节,已经形成了一系列行之有效的科学分析方法。文章有选择地结合实例,阐述了几种常用于战略决策的情报研究方法。

CAUSALITY DIAGRAM BASED SAFETY ANALYSIS OF MICRO TURBOJET ENGINE

An improved safety analysis based on the causality diagram for the complex system of micro aero-engines is presented.The study is examined by using the causality diagram in analytical failure cases due to rupture or pentration in the receiver of micro turbojet engine casing,and the comparisons are also made with the results from the traditional fault tree analysis.Experimental results show two main advantages：（1）Quantitative analysis which is more reliable for the failure analysis in jet engines can be produced by the causality diagram analysis;（2）Graphical representation of causality diagram is easier to apply in real test cases and more effective for the safety assessment.

Experimental study and numerical analysis on bearing behaviors of super-long rock-socketed bored pile groups

A centrifuge modeling test and a three-dimensional finite element analysis（FEA）of super-long rock-socketed bored pile groups of the Tianxingzhou Bridge are proposed.Based on the similarity theory,different prototypical materials are simulated using different indicators in the centrifuge model.The silver sand,the shaft and the pile cap are simulated according to the natural density,the compressive stiffness and the bending stiffness,respectively.The finite element method（FEM）is implemented and analyzed in ANSYS,in which the stress field during the undisturbed soil stage,the boring stage,the concrete-casting stage and the curing stage are discussed in detail.Comparisons in terms of load-settlement,shaft axial force distribution and lateral friction between the numerical results and the test data are carried out to investigate the bearing behaviors of super-long rock-socketed bored pile groups under loading and unloading conditions.Results show that there is a good agreement between the centrifuge modeling tests and the FEM.In addition,the load distribution at the pile top is complicated,which is related to the stiffness of the cap,the corresponding assumptions and the analysis method.The shaft axial force first increases slightly with depth then decreases sharply,and the rate of decrease in rock is greater than that in sand and soil.

Bayesian analysis for mixed-effects model defined by stochastic differential equations

The nonlinear mixed-effects model with stochastic differential equations （SDEs） is used to model the population pharmacokinetic （PPK） data that are extended from ordinary differential equations （ODEs） by adding a stochastic term to the state equation. Compared with the ODEs, the SDEs can model correlated residuals which are ubiquitous in actual pharmacokinetic problems. The Bayesian estimation is provided for nonlinear mixed-effects models based on stochastic differential equations. Combining the Gibbs and the Metropolis-Hastings algorithms, the population and individual parameter values are given through the parameter posterior predictive distributions. The analysis and simulation results show that the performance of the Bayesian estimation for mixed-effects SDEs model and analysis of population pharmacokinetic data is reliable. The results suggest that the proposed method is feasible for population pharmacokinetic data.

The quantified analysis of China's GM cotton yield capacity by C-D function and stochastic frontier model

Using a modified C D function and stochastic frontier model, the paper analyzed China's cotton yield capacity and found that the yield and technical efficiency of China's cotton planting system can be increased by the use of genetically modified (GM) varieties.

The single-machine scheduling problems with deteriorating jobs and learning effect

In this paper we consider a single-machine scheduling model with deteriorating jobs and simultaneous learning, and we introduce polynomial solutions for single machine makespan minimization, total flow times minimization and maximum lateness minimization corresponding to the first and second special cases of our model under some agreeable conditions. However, corresponding to the third special case of our model, we show that the optimal schedules may be different from those of the classical version for the above objective functions.

Discrimination for minimal hepatic encephalopathy based on Bayesian modeling of default mode network

In order to classify the minimal hepatic encephalopathy （MHE） patients from healthy controls, the independent component analysis （ICA） is used to generate the default mode network （DMN） from resting-state functional magnetic resonance imaging （fMRI）. Then a Bayesian voxel- wised method, graphical-model-based multivariate analysis （GAMMA）, is used to explore the associations between abnormal functional integration within DMN and clinical variable. Without any prior knowledge, five machine learning methods, namely, support vector machines （SVMs）, classification and regression trees （ CART ）, logistic regression, the Bayesian network, and C4.5, are applied to the classification. The functional integration patterns were alternative within DMN, which have the power to predict MHE with an accuracy of 98%. The GAMMA method generating functional integration patterns within DMN can become a simple, objective, and common imaging biomarker for detecting MIIE and can serve as a supplement to the existing diagnostic methods.

Laparoscopic distal pancreatectomy is as safe and feasible as open procedure:A meta-analysis

AIM:To evaluate the feasibility and safety of laparoscopic distal pancreatectomy(LDP) compared with open distal pancreatectomy(ODP).METHODS:Meta-analysis was performed using the databases,including PubMed,the Cochrane Central Register of Controlled Trials,Web of Science and BIOSIS Previews.Articles should contain quantitative data of the comparison of LDP and ODP.Each article was reviewed by two authors.Indices of operative time,spleen-preserving rate,time to fluid intake,ratio of malignant tumors,postoperative hospital stay,incidence rate of pancreatic fistula and overall morbidity rate were analyzed.RESULTS:Nine articles with 1341 patients who underwent pancreatectomy met the inclusion criteria.LDP was performed in 501(37.4%) patients,while ODP was performed in 840(62.6%) patients.There were significant differences in the operative time,time to fluid intake,postoperative hospital stay and spleen-preserving rate between LDP and ODP.There was no difference between the two groups in pancreatic fistula rate [random effects model,risk ratio(RR) 0.996(0.663,1.494),P = 0.983,I2 = 28.4%] and overall morbidity rate [random effects model,RR 0.81(0.596,1.101),P = 0.178,I2 = 55.6%].CONCLUSION:LDP has the advantages of shorter hospital stay and operative time,more rapid recovery and higher spleen-preserving rate as compared with ODP.

Efficiency Pattern and Spatial Strategy of Ports in Yangtze River Delta Region

This paper measures the efficiency of ports in the Yangtze River Delta Region(YRDR) in 2008 and 2013 using port berth quantity, quay length, and human resources as input indicators, using cargo and container throughput as output indicators, and considering traditional(foreign trade dependence and industrialization level) and modern environmental factors(traffic line density, financial development level, and informatization level). To achieve such aim, this study constructs a multi-stage data envelopment analysis model(DEA) that identifies effective port decision-making units(DMUs) and generates a highly accurate conclusion by eliminating the interference from the exogenous environment and random errors. First, the external environment significantly affects port efficiency, with the traditional environmental factors showing huge fluctuations and the modern environmental factors producing great benefits. Second, the efficiency of ports in YRDR has increased from 2008 to 2013 primarily because of their pure technical efficiency. Third, the weighted standard deviation ellipse(SDE) analysis results reveal that the efficiency pattern of ports significantly deviates from their throughput pattern, while the center of SDE of port efficiency moves from the eastern coastal regions to the northwest regions. Based on these findings, this paper proposes spatial development strategies for YRDR, such as creating an unblocked environment where spatial elements can freely circulate, intensifying port-city joint development, implementing differentiated policies, and focusing on the spatial collaboration of port efficiency.

ALTERNATING METHOD STUDY ON STRESS ANALYSIS OF SURROUNDING ROCK FOR TWO RANDOM GEOMETRY TUNNELS

The stress analysis of surrounding rock for two random geometry tunnels is studied in this paper by using Schwarz’s alternating method. The simple and effective alternating algorithm is found, in which the surplus surface force is approximated by Fourier series, thus the iteration derivation can be conducted according to the precision required, finally, the stress results with high precision are obtained.

Dynamic characteristic analysis of whole machine tools based on Kriging model

In order to study the variation of machine tools’dynamic characteristics in the manufacturing space,a Kriging approximate model is proposed.Finite element method(FEM)is employed on the platform of ANSYS to establish finite element(FE)model with the dynamic characteristic of combined interface for a milling machine,which is newly designed for producing aero engine blades by a certain enterprise group in China.The stiffness and damping of combined interfaces are adjusted by using adaptive simulated annealing algorithm with the optimizing software of iSIGHT in the process of FE model update according to experimental modal analysis(EMA)results.The Kriging approximate model is established according to the finite element analysis results utilizing orthogonal design samples by taking into account of the range of configuration parameters.On the basis of the Kriging approximate model,the response surfaces between key response parameter and configuration parameters are obtained.The results indicate that configuration parameters have great effects on dynamic characteristics of machine tools,and the Kriging approximate model is an effective and rapid method for estimating dynamic characteristics of machine tools in the manufacturing space.

Time between failures model and failure analysis of CNC system

To provide basis for the reliability improvement design of CNC system, the failure data of a type of CNC system in one year are collected under field conditions in workshops. The distribution model parameters of time between failures are estimated by least square method and hypothesis testing is done by d-test method. It is proved that the time between failures of the CNC system follows Weibull distribution and the system has entered into the wear-out failure period. The failure positions and failure causes are analyzed further to indicate the weak subsystems of the CNC system. It can be found that servo unit, electrical system, detecting unit and power supply are principal failure positions and the main failure cause is breakage of components. The corresponding improvement measures are put forward. The paper provides a reference to reliability design and analysis of CNC system for the manufacturer and has great guidance to using and maintaining CNC system for the user.

Random Vibration Analysis of Urban Underground Tunnels Under Vertical Earthquake Excitations Based on Mass–Damper–Spring Model

In this paper, the verticalseismic effects on tunnels are studied based on a classic mass–damper–spring model. An analyticaldiscrete modelof urban underground tunnels subjected to verticalearthquake excitations is proposed by considering the first verticalvibration mode. Taking a light railproject in Tianjin as an example, this study uses the proposed discrete modelto analyze the displacements of tunneland soilunder verticalearthquake excitations. The soildisplacement responses at different tunnellocations are analyzed with linear random vibration theory.The computationalcost is greatly reduced using the proposed model. It can be seen that different from the case of horizontalearthquakes, the displacement responses under verticalearthquake excitations keep growing after seismic acceleration reaches its peak for a short duration, and then,they begin to decay. The soils at different positions around the tunnels have large relative displacement under verticalearthquake excitations. Moreover, a finite-element modelis also established for displacement responses using ABAQUS.The comparison with the results of the finite-element modelshows that the results of the proposed discrete modelare available.

TACE combined with liver resection versus liver resection alone in the treatment of resectable HCC:a meta-analysis

Objective: The efficacy of preoperative transarterial chemoembolization(TACE) for hepatectomy on hepatocelluar carcinoma(HCC) is still controversial. This study aims to evaluate the efficacy of preoperative TACE on resectable HCC. Methods: Pubmed, SCI, Medline, EMBASE, Cochrane Datebase, CNKI were searched. The articles that focused on preoperative TACE for resectable HCC, published from 1990 to 2012, were collected by computerized search of literatures and manual search of bibliographies. The relevant clinical trials' data were reviewed by meta-analysis using the random effects model or fixed effect model by heterogeneity. The outcomes were expressed as odds ratio(OR) with 95% confidence intervals(CIs). Results: A total of 1347 patients were included in these 7 studies, the cases were divided into the preoperative TACE group and the non-preoperative TACE group, and there was no difference between the two groups in the 3-year disease-free survival rate, with an odds ratio of 1.14(95% CI = 0.90–1.45, P = 0.27); the 5-year disease-free survival rate in the preoperative TACE group was better than that in the non-TACE group with an odds ratio of 1.35(95% CI = 1.07–1.74, P = 0.02); the 5-year overall survival rate in the preoperative TACE group was higher than that in the non-TACE group with an odds ratio of 0.59(95% CI = 0.46–0.77, P < 0.0001). Conclusion: The present data suggests that preoperative TACE has no different in improving the 3-year disease-free survival rate with non-TACE group for resectable HCC, while it can improve the 5-year disease-free survival rate and the 5-year overall survival rate. More randomized controlled trials using large sample size are needed to provide sufficient evidence to confirm current conclusion.