水平井完井方式优选

本文详述水平井完井方式选择的一般步骤,包括井壁稳定性及出砂判断的数学模型、考虑了多种因素对完井方式选择的影响。     

比例时滞线性系统的反馈镇定

研究了比例时滞线性系统的反馈镇定问题．利用标准反馈控制与时滞反馈控制实现系统不稳定平衡点的镇定．构造合适的李亚普诺夫泛函，得出了闭环系统稳定的几个充分条件．通过实例说明了方法的有效性．     

现代高校网络解决方案

本文根据高校校园网建设的需求分析,探讨了针对校园网建设所涉及的重要问题,即稳定可靠、管理、安全性、升级等几个重点方面并简要的介绍了其解决方案.     

软岩采场边界失稳原因分析及应对措施

从放矿过程、爆破震动、上覆岩等方面对有底部结构空场法侧壁失稳的原因进行了深入研究，提高了对边界失稳机理的认识；同时，在对大量采场边界失稳观测和分析的基础上，提出了坍塌角经验公式，并以此为依据提出对策。通过生产实践证明，采取的措施行之有效，能避免边界失稳带来的影响，使采切工程和落矿中深孔的布置更具合理性。     

Locking and hourglass phenomena in an element‐free Galerkin context: the B‐bar method with stabilization and an enhanced strain method

The meshless methods, namely the element‐free Galerkin method (EFGM), when they first appeared claimed that volumetric locking and hourglass were avoided. This was not the case and both phenomena occur in the EFGM. In the context of the finite element method (FEM) these phenomena were widely studied. In this work, forms of avoiding the locking phenomenon will be presented; a formulation based on the enhanced strain method will be introduced in the EFGM and the B‐bar method will be implemented under the scope of the EFGM. Secondly, to render this method more robust, a stabilization technique will be implemented avoiding hourglass. Several examples are solved to probe the efficiency of these techniques. Copyright © 2006 John Wiley & Sons, Ltd.     

济钢烧结节能降耗与工艺优化技术应用

结合济钢烧结厂的生产实际，从技术、管理及操作等各个方面，致力于多项节能技术的开发，使烧结生产的各种能源介质单耗明显下降。     

Preliminary Assessment and Rating of Stream Channel Stability near Bridges

The primary cause of bridge failure in the United States is scour and channel instability around the bridge foundations. The ability to assess channel stability in the vicinity of bridges is needed to alert engineers to possible unstable conditions at the bridge foundations, to design stable road crossings, and to mitigate against erosion at those structures. This information is valuable for stream stabilization projects as well, particularly for cases where the reach to be restored includes a bridge. However, a systematic methodology for rapidly assessing channel stability that is applicable at bridges located in the various regions of the country does not currently exist. In this study, an assessment method for the preliminary documentation and rating of channel stability near bridges was developed, based on prior stability assessment methods as well as observations at bridges in 13 physiographic regions of the continental United States. This method provides an assessment of channel stability conditions as they affect bridge foundations. It is intended for a quick assessment of conditions for the purpose of documenting conditions at bridges and for judging whether more extensive geomorphic studies or complete hydraulic and sediment transport analyses are needed to assess the potential for adverse conditions developing at a particular bridge in the future.     

Case Study: River Training and Its Effects on Fluvial Processes in the Lower Yellow River, China

More than 50?years’ river training practices in the Lower Yellow River provide valuable experience in river management for flood control in rivers having rapid flow changes, silting beds, and active channel migrations and are of importance in understanding the fluvial processes in regulated rivers with high sediment loads. Planned channel alignments for river training in the Lower Yellow River usually consist of a series of consecutive moderate bends representing the natural tendency of flows. Flow guide works, namely spur dikes, were constructed on the concave banks of the planned bends to protect the channel against scouring and migration by deflecting the current away from bends and further guiding the main flow from one bend to the next one. As a result, well-planned flow guide works can play a crucial role in limiting channel shifting and migration and in establishing a relatively stable channel. Enough flow guide works, on both sides together reaching about 80% of the channel length, may change the transitional and braided channel patterns to a confined meandering pattern.     

Magnetic Field Stabilization for Magnetically Shielded Volumes by External Field Coils

For highly sensitive magnetic measurements, e.g., a measurement of the neutron electric dipole moment (EDM), the magnetic field has to be stable in time on a level below picoTesla. One of several measures we employ to achieve this uses an external field coil system which can stabilize the ambient external field at a predefined value. Here we report on the construction and characterization of such a system in the magnetic test facility at PSI. The system actively stabilizes the field along the axis of the EDM experiment by means of four coils in a Helmholtz-like configuration. Additional coils serve to compensate for transverse ambient field components. Because of the long integration times in the EDM experiment (about 100 s or more) only slow disturbances have to be corrected for. The performance of the system has been measured using static and moving magnetic sources and suppression factors in excess of 200 have been observed.     

On bounds for the existence of a bistable controller

By we shall denote the set of polynomials nonzero on the closed disk {z: |z|r}. The problem to be studied is given as follows.Avoidance Problem. Given polynomials A and B, nonnegative integers n, m, and positive numbers r₁, r₂, r₃, determine if there exist , with degrees n and m, respectively, such that AP+BQ is in .It is shown that the Avoidance Problem for r₁=r₂=r₃=1 is equivalent to the well-known Bistable Stabilization Problem for a large class of control systems.Also, a general class of optimization problems for solving the Avoidance Problem is introduced. The class of optimization problems includes problems with sets more general than disks . In addition, an algorithm is proposed for solving these optimization problems, and numerical experience is reported.As an application, bistable controllers for the plant are shown to exist for values of β as low as 0.0246, thus improving on previously reported results by Blondel et al. for this difficult case.Furthermore, it is shown how in some cases it is possible to find optimal controllers by using a combination of numerical and algebraic techniques, and a variant of the algorithm already introduced. As an example, a low order controller is found for for the case when .This method could be applied to other problems where the plant depends on a parameter.