Research on cohesive sediment erosion by flow: An overview

Erosion of cohesive sediment by flow is a very complicated phenomenon occurring worldwide. Understanding and modeling of the erosion process are important for many issues such as the breaching of embankments, riverbank stability, siltation of harbors and navigation channels, service life of reservoirs, distribution of (heavy metal) pollutants and water quality problems. In the last few decades, numerous studies have been done on the erosion of cohesive sediment by flow. Nevertheless, the factors affecting the erosion resistance of cohesive sediment are still not fully understood and the knowledge of the physics of cohesive sediment erosion is inadequate, as a result the mathematical modeling of this erosion is far from satisfactory. In this paper an overview of the studies on the erosion resistance, erosion threshold and the erosion rate of cohesive sediment by flow is presented. The outcomes achieved so far from the studies and the existing problems have been analyzed and summarized, based on which recommendations are proposed for future research. Supported by the National Key Technology R&D Program of China (Grant Nos. 2006BAC14B02 and 2006BAB05B03) and the National Basic Research Program (973 Program) of China (Grant No. 2007CB714106)     

The effect of manganese and sulfur contents on the magnetic properties of cold rolled lamination steels

The effect of Mn and S contents on the magnetic properties of cold rolled lamination steel was investigated in eleven low C steels. The results indicated that Mn content was a major factor influencing the magnetic quality of the lamination steels. An optimum range of Mn was a prerequisite for optimum permeability and exciting power. For Mn contents up to 1.25 Pct, the core loss improved nonlinearly with increasing Mn content. At higher Mn contents, the magnetic properties deteriorated for the experimental conditions used as a consequence of poor grain size development after the final decarburizing anneal. Decreasing the S content from 0.018 Pct to 0.010 Pct improved the core loss at all induction levels. The permeability and exciting power were improved at 1 T, but a very slight deterioration in permeability and exciting power was seen at 1.5 and 1.7 T. Estimations of core loss improvement based on regression equations indicated that lowering the S content from 0.018 Pct to 0.010 Pct improved the core loss in w/lb-mil as follows: 0.0041 at 1 T, 0.0079 at 1.5 T, and 0.0093 at 1.7 T (1 w/lb-mil = 86.8 w/kg-mm). The response surface analyses indicated that Mn content in the range of 0.7 Pct to 1 Pct, depending on the S content, should develop optimum magnetic properties. However, Mn content at the low end of this range is preferred for practical applications. This paper is based on a presentation made at the symposium “Physical Metallurgy of Electrical Steels” held at the {dy1985} annual AIME meeting in New York on February 24–28, {dy1985}, under the auspices of the TMS Ferrous Metallurgy Committee.     

集成式液面自动监测系统的研制与应用

常规液面测试不能连续即时测试,也不能长期持续监测油井液面变化情况,不满足海上平台多油井集中统一、大规模应用的需要。研制出了集成式液面自动监测系统。介绍了集成式液面自动监测系统的基本结构和工作原理,并对该系统在CB-B平台的应用进行了分析。现场试验表明,集成式液面自动监测系统达到了安全生产实际要求,能够满足油井静动液面测试的需要,实现了海上平台多井测试系统集成化、模块化。     

Clutter suppression method for heterogeneous environment

Clutter suppression is a key process in ground moving target indication (GMTI). Adaptive filtering is an effective method for clutter suppression but the performance degrades severely in heterogeneous clutter environment. To solve this problem, a new clutter suppression method is proposed. The approach uses subspace tracking technique to update clutter subspace of different clutter patches which may mitigating the heterogeneous effects. Simulation results illustrate that the method performs well when lacking of the independent and identically distributed (i.i.d.) samples.     

模袋混凝土抢险加固水下护坦

本工程位于广东省东江河附城段，是东江河与运河的控制水闸，运河具有灌溉功能，水闸上游正常水位2．8m～3．5m，下游正常水位-0．5m～-1．2m。由于水闸建设在砂层地质上，且具有通航要求，水闸内外水位高差有3．3m～4．7m，水流的冲刷造成原有的水闸护坦底部淘空及左右岸挡墙拉裂，严重影响了水闸安全，对护坦的加固迫在眉捷。护坦已延伸到东江河床边，其顶面高程为-3．8m，水深约3m，如采用常态混凝土加固，势必要封航、做止水围堰。而且在砂层上做止水围堰，施工难度大，经济投入也较大。     

Theory of initially twisted, composite, thin-walled beams

An asymptotically correct theory for initially twisted, thin-walled, composite beams has been constructed by the variational asymptotic method. The strain energy of the original, three-dimensional structure is first rigorously reduced to be a two-dimensional energy expressed in terms of shell strains. Then the two-dimensional strain energy is further reduced to be expressed in terms of the classical beam strain measures. The resulting theory is a classical beam model approximating the three-dimensional energy through the first-order of the initial twist. Consistent use of small parameters that are intrinsic to the problem allows a natural derivation for all thin-walled beams within a common framework, regardless of whether the section is open, closed, or strip-like. Several examples are studied using the present theory and the results are compared with a general cross-sectional analysis, VABS, and other published results.     

间三氟甲基肉桂酸的合成

以间三氟甲基苯胺为起始原料,经重氮化、甲醛肟甲酰化、缩合等三步反应,合成了高纯度的间三氟甲基肉桂酸,总产率为32.0%,并用FT-IR,1HNMR进行了表征。结果表明,最佳反应条件为:在缩合反应中,间三氟甲基苯甲醛/丙二酸/吡啶/无水乙醇(摩尔比)为1:1.11:0.17:3.98,回流6h。     

小长径比药盘钢模压制成型工艺研究

通过对炸药压装成型过程的深入分析，揭示了钢模压制小长径比药盘的技术关键是必须使所装填的散粒体炸药在压件的横断面上全面实现其质量的合理分配，设计定程式双向钢质压模，合理确定垫圈厚度和括药器结构。