Deviation correction strategy for the earth pressure balance shield based on shield–soil interactions

The control system presently used in shield posture rectification is based on driver experience, which is marginally reliable. The study of the related theory is flawed. Therefore, a decision-making approach for the deviation correction trajectory and posture rectification load for an earth pressure balance (EPB) shield is proposed. A calculation model of posture rectification load of an EPB shield is developed by considering the interactions among the cutter head, shield shell, and ground. The additional position change during the shield attitude correction is highlighted. The posture rectification loads and shield behaviors results can be solved by the proposed method. The influences of the stratum distribution (i.e., bedrock height in the upper-soft and lower-hard strata) on shield behaviors and posture rectification loads are analyzed. Results indicated that the increase of pitch angle in the upper-soft and lower-hard strata causes a sharp rise in vertical displacement. The bedrock height increases the magnitudes of the required posture rectification moments when h_r/D > 0.5. For a tunnel with h_r/D ≤ 0.5, the variation of h_r/D has little effect on the posture rectification moments. Finally, the posture rectifying curves based on the theoretical model are compared with the target ones based on the double circular arc interpolation method. The required results can be obtained regardless of the soil–rock compound stratum distribution. The maximum rectification moment in the rock layer is almost 12.6 times that in the soil layer. Overall, this study provides a valuable reference for moment determination and the trajectory prediction of posture rectification in compound strata.     

矿山灾害应急救援生命保障孔钻井工艺研究

近年来国内外开展的救援钻孔实践推动了矿山和地下工程应急救援技术的发展,探索出的“小直径生命保障孔+大直径救生孔”模式是进行矿山和地下工程灾害救援的一种有效途径。本文以矿山灾害救援地面生命保障孔钻井工艺为主线,分析了小直径生命保障孔井身结构设计和套管选用方法;分别介绍了泥浆正循环钻进工艺和空气潜孔锤正循环钻进工艺,并以山东栖霞笏山金矿生命救援孔钻进实例分析了当前生命保障孔钻井工艺难点。依据轨迹设计理论,针对笏山金矿救援3号生命保障孔出现的偏斜问题,创新提出了超短距离螺旋纠偏技术,并取得了良好的应用效果,为后续生命保障孔施工积累了宝贵经验。     

摆辗机新型螺旋线运动轨迹研究

针对双偏心套摆辗机摆头的螺旋线运动轨迹,根据摆头运动原理,建立摆头运动方程,提出并分析摆头新型螺旋线运动轨迹的形成,总结该运动轨迹变化规律,为改进摆头结构、设计新型摆辗机、拓展摆辗成形工艺提供理论指导。     

安塞低渗油田水平多分支井钻井技术

针对安塞油田低渗透油藏地质特征,结合分支井开发方式的适应性及其技术特点,通过对分支井井身结构优化、钻头选型、轨迹控制、分支井眼侧钻、地质导向、摩阻扭矩分析等技术的研究和应用,成功完成了安塞油田第1口水平多分支井-杏平1井。该井完钻井深5068 m,水平位移1574.22 m,主水平段长1203 m,水垂深比1.16。在只能使用常规钻井设备及导向工具等难题下,成功采用低边侧钻技术在主水平段内侧钻了7个分支井眼,分支井眼总长2300m,累计打开目的储层3503 m,并实现了多次重入钻井,初步形成了适合安塞油田地质特点的分支井钻井技术。     

Using a phenomenological computer model to investigate advanced combustion trajectories in a CIDI engine

This paper summarizes results from simulations of conventional, high-dilution, and high-efficiency clean combustion in a diesel engine based on a two-zone phenomenological model. The two-zone combustion model is derived from a previously published multi-zone model, but it has been further simplified to increase computational speed by a factor of over 100. The results demonstrate that this simplified model is still able to track key aspects of the combustion trajectory responsible for NO_x and soot production. In particular, the two-zone model in combination with highly simplified global kinetics correctly predicts the importance of including oxygen mass fraction (in addition to equivalence ratio and temperature) in lowering emissions from high-efficiency clean combustion. The methodology also provides a convenient framework for extracting information directly from in-cylinder pressure measurements. This feature is likely to be useful for on-board combustion diagnostics and controls. Because of the possibility for simulating large numbers of engine cycles in a short time, models of this type can provide insight into multi-cycle and transient combustion behavior not readily accessible to more computationally intensive models. Also the representation of the combustion trajectory in 3D space corresponding to equivalence ratio, flame temperature, and oxygen fraction provides new insight into optimal combustion management.     

Experiment and analysis on microscopic characteristics of pedestrian movement in building bottleneck

In this paper, evacuation experiments are carried out to study pedestrian movement behaviors in building bottleneck. An image processing method based on mean-shift algorithm is used to extract pedestrian movement trajectory. Based on the extracted trajectory, we analyze the microscopic movement characteristics of pedestrians such as lane formation, change of velocity and distance between two sequential pedestrians. A pedestrian lane is a group of pedestrians moving in a column. The lane formation is verifie...     

A Basic Study of User Utility Maximizing Content Retrieval from Information Networks

This paper proposes some basic methods of content search yielding high user utility or user's satisfaction from numerous information sources scattered over large‐scale networks. In these methods, the search policy is decided by the estimated user utility gain and/or current user utility for each search action, and the most favorable combination of information sources and search content items is selected so as to enlarge the total user utility of the entire search activity. In addition, we evaluate the efficiency of the methods by computer simulations, in which we specify the network topology, user utility functions, probabilities of existence of the search content items in each information source, and so on, apply the proposed methods and other methods for comparison, and compare their aggregate utility gains as an estimation index. The proposed methods are found to achieve good performance in general and an index value about 2.45 times that of ordinary search is observed in an extreme simulation scenario. We discuss the pros and cons of the proposed methods for all the simulation scenarios.     

Topological-based bottleneck analysis and improvement strategies for traffic networks

A method is proposed to find key components of traffic networks with homogenous and heterogeneous topologies, in which heavier traffic flow is transported. One component, called the skeleton, is the minimum spanning tree (MST) based on the zero flow cost (ZCMST). The other component is the infinite incipient percolation cluster (IIC) which represents the spine of the traffic network. Then, a new method to analysis the property of the bottleneck in a large scale traffic network is given from a macroscopic an...     

Design and interpretation of cell trajectory assays

Cell trajectory data are often reported in the experimental cell biology literature to distinguish between different types of cell migration. Unfortunately, there is no accepted protocol for designing or interpreting such experiments and this makes it difficult to quantitatively compare different published datasets and to understand how changes in experimental design influence our ability to interpret different experiments. Here, we use an individual-based mathematical model to simulate the key features of a cell trajectory experiment. This shows that our ability to correctly interpret trajectory data is extremely sensitive to the geometry and timing of the experiment, the degree of motility bias and the number of experimental replicates. We show that cell trajectory experiments produce data that are most reliable when the experiment is performed in a quasi-one-dimensional geometry with a large number of identically prepared experiments conducted over a relatively short time-interval rather than a few trajectories recorded over particularly long time-intervals.