奥-贝球墨铸铁制焊管预弯机下预弯模具的可行性研究

采用球化+二次孕育以及等温淬火工艺制备了球化等级为2级的奥-贝球墨铸铁,比较了奥-贝球墨铸铁、珠光体球墨铸铁和Cr12Mo1V1冷作模具钢的力学性能和摩擦磨损特性。结果表明:奥-贝球墨铸铁具有良好的力学性能和优异的摩擦磨损性能,组织中的贝氏体在摩擦磨损中可以有效地传递应力和起到支撑作用,提高了其抗磨性;较高的硬度和弹性模量以及石墨进入磨损表面润滑,减小了摩擦因数。认为采用奥-贝球墨铸铁制备焊管预弯机的下预弯模具具有可行性。

隔震工程下支墩混凝土及预埋板施工技术分析

建筑隔震工程中下支墩混凝土及隔震支座下预埋板施工,常出现混凝土密实度不足和预埋板安装、定位精度不合格,影响结构安全和隔震结构减震性能。针对下支墩(柱)混凝土施工通常采取的3种浇筑方式进行分析,提出宜采用高强灌浆料后灌浆或者细石混凝土二次浇筑的施工方法,对下预埋钢板制作所涉及的开孔、套筒、螺栓、锚筋等数量及连接方式等进行分析,建议不应采用较薄的定位板代替下预埋板,提出套筒表面应当采用螺纹、锚筋与下预埋板采用螺纹连接、下预埋板应当设置销钉等的要求。

Computational implementation of a GIS developed tool for prediction of dynamic ground movement and deformation due to underground extraction sequence

In the last century, there has been a significant development in the evaluation of methods to predict ground movement due to underground extraction. Some remarkable developments in three-dimensional computational methods have been supported in civil engineering, subsidence engineering and mining engineering practice. However, ground movement problem due to mining extraction sequence is effectively four dimensional （4D）. A rational prediction is getting more and more important for long-term underground mining planning. Hence, computer-based analytical methods that realistically simulate spatially distributed time-dependent ground movement process are needed for the reliable long-term underground mining planning to minimize the surface environmental damages. In this research, a new computational system is developed to simulate four-dimensional （4D） ground movement by combining a stochastic medium theory, Knothe time-delay model and geographic information system （GIS） technology. All the calculations are implemented by a computational program, in which the components of GIS are used to fulfill the spatial-temporal analysis model. In this paper a tight coupling strategy based on component object model of GIS technology is used to overcome the problems of complex three-dimensional extraction model and spatial data integration. Moreover, the implementation of computational of the interfaces of the developed tool is described. The GIS based developed tool is validated by two study cases. The developed computational tool and models are achieved within the GIS system so the effective and efficient calculation methodology can be obtained, so the simulation problems of 4D ground movement due to underground mining extraction sequence can be solved by implementation of the developed tool in GIS.

Groundwater level prediction based on hybrid hierarchy genetic algorithm and RBF neural network

As the traditional non-linear systems generally based on gradient descent optimization method have some shortage in the field of groundwater level prediction, the paper, according to structure, algorithm and shortcoming of the conventional radial basis function neural network （RBF NN）, presented a new improved genetic algorithm （GA）： hybrid hierarchy genetic algorithm （HHGA）. In training RBF NN, the algorithm can automatically determine the structure and parameters of RBF based on the given sample data. Compared with the traditional groundwater level prediction model based on back propagation （BP） or RBF NN, the new prediction model based on HHGA and RBF NN can greatly increase the convergence speed and precision.

Inversion and Prediction of Consolidation Settlement Characteristics of the Fluvial Sediments Based on Void Ratio Variation in the Northern Modern Yellow River Subaqueous Delta, China

The modern Yellow River delta is formed near the estuary of the Yellow River with the characteristics of short formation time, efficient sedimentation rate and loose structure which make sediments prone to be compacted and consolidate under the geostatic stress and overburden stress. It is one of the key areas with land subsidence disasters in China, bringing a series of safety hazards to production and living. Based on the data of massive surface cores and ten drill holes ranging from 12 to 40 m obtained from the northern modern Yellow River subaqueous delta, the inversion method suitable for the calculation of consolidation settlement characteristics of the modern Yellow River subaqueous delta is discussed, and the consolidation settlement characteristics of the delta sediments are inversed and predicted in this paper. The actual void ratio of the delta sediments at the depth from 3 to 15 m shows a significant power function relationship with the depth, while the void ratio of the sediments below 15 m changes little with depth. The pre-consolidation settlement(from deposition to sampling) of the delta sediments is between 0.91 and 1.96 m, while the consolidation settlement of unit depth is between 9.6 and 14.0 cm m^(-1). The post-consolidation settlement(from sampling to stable) of the subaqueous delta sediments is between 0.65 and 1.56 m in the later stage, and the consolidation settlement of unit depth is between 7.6 and 13.1 cm m^(-1) under the overburden stress. The delta sediments with a buried depth of 3 to 7 m contribute the most to the possible consolidation settlement in the later stage.

考虑既有船坞的深基坑工程设计

本工程地处城市中心区复杂环境,既有船坞位于基坑范围内,这种情况的审计工程尚属国内先例。本文针对既有船坞对基坑工程的影响,介绍了基坑支护设计,如既有船坞主体结构及下部桩基障碍物清除、围护墙在既有船坞结构与工程桩重叠时的实施、船坞底板下工程桩拔出及承压水层突涌风险控制、船坞底板下桩基遭遇实际桩位同图纸偏差时的风险控制、既有船坞结构与支护结构衔接等。实践表明,相应的设计技术有效地保证了工程工期、基坑安全及周边环境的安全。

Machine learning strategies for lithostratigraphic classification based on geochemical sampling data: A case study in area of Chahanwusu River, Qinghai Province, China

Based on the complex correlation between the geochemical element distribution patterns at the surface and the types of bedrock and the powerful capabilities in capturing subtle of machine learning algorithms,four machine learning algorithms,namely,decision tree(DT),random forest(RF),XGBoost(XGB),and LightGBM(LGBM),were implemented for the lithostratigraphic classification and lithostratigraphic prediction of a quaternary coverage area based on stream sediment geochemical sampling data in the Chahanwusu River of Dulan County,Qinghai Province,China.The local Moran’s I to represent the features of spatial autocorrelations,and terrain factors to represent the features of surface geological processes,were calculated as additional features.The accuracy,precision,recall,and F1 scores were chosen as the evaluation indices and Voronoi diagrams were applied for visualization.The results indicate that XGB and LGBM models both performed well.They not only obtained relatively satisfactory classification performance but also predicted lithostratigraphic types of the Quaternary coverage area that are essentially consistent with their neighborhoods which have the known types.It is feasible to classify the lithostratigraphic types through the concentrations of geochemical elements in the sediments,and the XGB and LGBM algorithms are recommended for lithostratigraphic classification.

Predictive factors of endoscopic submucosal dissection procedure time for gastric superficial neoplasia

AIM:To identify the determinants of endoscopic submucosal dissection(ESD) operation time.METHODS:This investigation was conducted as a single-center,prospective study in which ESD was performed by the same endoscopist at the Chinese PLA General Hospital.A total of 173 patients underwent ESD operations performed by Dr.Lu from July 2007 to December 2011,and 183 lesions were enrolled.Patient gender,age,tumor location,gross type,tumor size,pathological type and adhesions were recorded prospectively.The order of treatment represented the experience of the operator.Univariate analysis and multivariate analysis were performed to evaluate the relationships between these factors and ESD procedure time.RESULTS:Univariate analysis showed the ESD time was closely related to the gender(P = 0.0210),tumor size(P < 0.0001),location(P < 0.0001),gross type(P < 0.0001) and adhesion(P = 0.0010).The surgical proficiency level was associated with ESD time in unit area(P < 0.0001).Multivariate analysis revealed that the ESD time was positively correlated with tumor size(P < 0.0001),adhesion(P < 0.0001) and location(P < 0.0001),but negatively correlated with surgical proficiency level(P = 0.0046).CONCLUSION:Large tumor size,adjacency to the cardia,and adhesion are predictors of a long ESD time,whereas high surgical proficiency level predicts a short ESD time.

Emotional Costs and Self-efficacy as Predictors of Coping Among the Reemployed and Professional Interns

The main goal of the study was to investigate the emotional costs experienced by the organizational newcomers during the first period of reemployment and its relation to general self-efficacy CGSE} and coping. The study was conducted among 123 previous unemployed, involving 88 reemployed and 35 interns. Questionnaires battery was administered in two waves {T1 and T2~ in the first month of reemployment and after three months. In this article, the data from T2 were analyzed, which allows observing the final results and interactions between research variables. The results showed emotional costs and GSE as significant predictors of coping in the work re-entry phase. Additionally, emotional costs partially mediate the effect of GSE on coping. The differences between both groups, the reemployed and interns were also analyzed.

GAS DETECTING AND FORECASTING VIA TIME SERIES METHOD

The importance and urgency of gas detecting and forecasting in underground coal mining are self-evident. Unfortunately, this problem has not yet been solved thoroughly.In this paper, the author suggests that the time series analysis method be adopted for processing the gas stochastic data. The time series method is superior to the conventional Fourier analysis in some aspects, especially, the time series method possesses forecasting (or prediction) function which is highly valuable for gas monitoring.An example of a set of gas data sampled from a certain foul coal mine is investigated and an AR (3) model is established. The fitting result and the forecasting error are accepted satisfactorily.At the end of this paper several remarks are presented for further discussion.

Effect of discontinuities characteristics on coal mine stability and sustainability： A rock fall prediction approach

Rock fall related accidents continue to occur in coal mines,although artificial support mechanisms have been used extensively. Roof stability is primarily determined in many underground mines by a limited number of methods that often resort to subjective criteria. It is argued in this paper that stability conditions of mine roof strata,as a key factor in sustainability in coal mines,must be determined by a survey which proactively investigates fundamental aspects of said mine. Failure of rock around the opening happens as a result of both high rock stress conditions and the presence of structural discontinuities. The properties of such discontinuities affect the engineering behavior of rock masses causing wedges or blocks to fall from the roof or sliding out of the walls. A practical rule-based approach to assess the risk of a roof fall is proposed in the paper. The method is based on the analysis of structural data and the geometry and stability of wedges in underground coal mines. In this regard,an accident causing a huge collapse in a coal mine leading to 4 fatalities is illustrated by way of a case study. Horizontal and vertical profiles are prepared by geophysical methods to define the falling zone and its boundaries. The collapse is then modeled by the use of sophisticated computer programs in order to identify the causes of the accident.

Wheel slip-sinkage and its prediction model of lunar rover

In order to investigate wheel slip-sinkage problem, which is important for the design, control and simulation of lunar rovers, experiments were carried out with a wheel-soil interaction test system to measure the sinkage of three types of wheels in dimension with wheel lugs of different heights and numbers under a series of slip ratios (0-0.6). The curves of wheel sinkage versus slip ratio were obtained and it was found that the sinkage with slip ratio of 0.6 is 3-7 times of the static sinkage. Based on the experimental results, the slip-sinkage principle of lunar's rover lugged wheels (including the sinkage caused by longitudinal flow and side flow of soil, and soil digging of wheel lugs) was analyzed, and corresponding calculation equations were derived. All the factors that can cause slip sinkage were considered to improve the conventional wheel-soil interaction model, and a formula of changing the sinkage exponent with the slip ratio was established. Mathematical model for calculating the sinkage of wheel according to vertical load and slip ratio was developed. Calculation results show that this model can predict the slip-sinkage of wheel with high precision, making up the deficiency of Wong-Reece model that mainly reflects longitudinal slip-sinkage.

Data Dependent Modeling of New Contamination Cases from Urban Historic Groundwater Records

Groundwater is the water located beneath the earth＇s surface in the soil pore spaces and in the fractures of rock formations. As one of the most important natural resources, groundwater is associated with the environment, public health, welfare, and long-term economic growth, which affects the daily activities of human beings. In modern urban areas, the primary contaminants of groundwater are artificial products, such as gasoline and diesel. To protect this important water resource, a series of efforts have been exerted, including enforcement and remedial actions. Each year, the TGPC （Texas Groundwater Protection Committee） in US publishes a ＂Joint Groundwater Monitoring and Contamination Report＂ to describe historic and new contamination cases in each county, which is an important data source for the design of prevention strategies. In this paper, a DDM （data dependent modeling） approach is proposed to predict county-level NCC （new contamination cases）. A case study with contamination information from Harris County in Texas was conducted to illustrate the modeling and prediction process with promising results. The one-step prediction error is 1.5%, while the two-step error is 12.1%. The established model can be used at the county-level, state-level, and even at the country-level. Besides, the prediction results could be a reference during decision-making processes.

An overview of intelligent selection and prediction method in heterogeneous wireless networks

Heterogeneous wireless access technologies will coexist in next generation wireless networks.These technologies form integrated networks,and these networks support multiple services with high quality level.Various access technologies allow users to select the best available access network to meet the requirements of each type of communication service.Being always best connected anytime and anywhere is a major concern in a heterogeneous wireless networks environment.Always best connected enables network selection mechanisms to keep mobile users always connected to the best network.We present an overview of the network selection and prediction problems and challenges.In addition,we discuss a comprehensive classification of related theoretic approaches,and also study the integration between these methods,finding the best solution of network selection and prediction problems.The optimal solution can fulfill the requirements of the next generation wireless networks.

Development and Construction of 345 kV Power-Optical Fiber Composite XLPE 2,500 mm2 with Prefabricated Joint

Due to the increasing demand of replacing large capacity overhead lines with underground cables in Korea, KEPCO （Korea Electric Power Corporation） and LS Cable （LS Cable ＆ System） have developed 345 kV optical fiber composite XLPE （cross-linked polyethylene） 2,500 mm2 cable system. This system has been installed in Cheongna district of Incheon city. KEPCO and LS Cable are also planning to build the cooling system in a tunnel in order to reduce the ambient temperature caused by currents. In this paper, the process of development, field installation, and final inspection test of the complete system will be described.

Application of phase space reconstruction and v-SVR algorithm in predicting displacement of underground engineering surrounding rock

A new method for predicting the trend of displacement evolution of surroundingrock was presented in this paper.According to the nonlinear characteristics of displace-ment time series of underground engineering surrounding rock,based on phase spacereconstruction theory and the powerful nonlinear mapping ability of support vector ma-chines,the information offered by the time series datum sets was fully exploited and thenon-linearity of the displacement evolution system of surrounding rock was well described.The example suggests that the methods based on phase space reconstruction and modi-fied v-SVR algorithm are very accurate,and the study can help to build the displacementforecast system to analyze the stability of underground engineering surrounding rock.

Study on the trajectory prediction curves of supercavitating vehicle

In order to understand the laws of motion for supercavitating vehicle better, simplified equations for longitudinal motion of supercavitating vehicle were derived. Then the corresponding simulation software for trajectory of supereavitating vehicle was programmed, by which the theoretical predicted trajectories of the supercavitating vehicle at different velocities were obtained. It was found that the predicted trajectories at low speed and without cavitation on the vehicle in theory agreed well with those in experiments, and the theoretical predicted trajectories at high speed and with supercavity on the vehicle correctly reflected the motion laws of the supercavitating vehicle. The influences of various parameters of eavitator and rudder on the underwater trajectory were compared and analyzed, which can provide a guide for the design of hydrodynamic distribution and gross parameters of the supereavitating weapons.

AN IMPACT STUDY OF A NEW TYPE OF DATA OF ADAPTIVE OR TARGETING OBSERVATION ON TYPHOON FORECAST

There was a new concept of ‘adaptive or targeting observation’ in recent years, which is anadditional and targeting observation based on the existing and fixed observing network for the atmosphere on theimpacted region. Dropsonde is one of the important observing instruments in the adaptive or targetingobservation. In this paper, GRAPES, the next generation of numerical weather prediction system of China hasbeen used. The impacts on the typhoon Dujuan (No.200315) forecast in experiments with dropsonde have beenstudied and experiments on sensitivity have also been done. It was found that the forecasts of the elements havebeen improved obviously with the use of dropsonde, such as the path, the center location, and the intensity oftyphoon. It was also found in the sensitivity studies that the setting of deviation structure also has obviousimpacts on the forecast for typhoons. It is not true that the simulation is better when the proportion of the data ofdropsonde is larger in the course to modify the background.

A Study on Simple Prediction Method of Heat Load： A Use of Linear Approximation Indicial Response in Basements

This study was conducted to establish a predictable method for a heat load of an underground structure with sufficient accuracy. As the first step, our previous paper reported the measurement results of field experiments on an underground experimental basement under internal heat generation conditions. Also, it presented the results of numerical analyses on the heat and moisture behavior and the influence of internal heat generation of the experimental basement and ground. However, it is practically impossible to utilize the model of simultaneous heat and moisture transfer at the design phase because the prediction by the model of simultaneous heat and moisture transfer requires a long calculation time. In this paper, the authors present the simple load calculation technique, using a linearized approximation indicial response of the inner surface heat flux in a basement to outdoor air temperature change. In addition, the approximation indicial responses for each part of the single-walled concrete drawn using this technique are arranged. The heat load calculation example of application to the basement of the optional size by this technique is shown.

Finite layer and triangular prism element method to subsidence prediction and stress analysis in underground mining

The application of the finite layer & triangular prism element method to the 3D ground subsidence and stress analysis caused by mining is presented. The layer elements and the triangular prism elements have been alternatively used in the numerical simulation system, the displacement pattern, strain matrix, elastic matrix, stiffness matrix, load matrix and the stress matrix of the layer element and triangular prism element have been presented. By means of the Fortran90 programming language, a numerical simulation system based on finite layer & triangular prism element have been built up, and this system is suitable for subsidence prediction and stress analysis of all mining condition and mining methods. Comparing with the infinite element method, this approach dramatically reduces the size of the set of equations that need to be solved, and greatly reduces the amount of data preparation required. It not only saves the internal storage, and the computation time, but also decreases the cost.