1780线除鳞水油站改造及稳定运行研究

承钢1780生产线除鳞水油站设备配置较低,甚至在设计和制造中存在缺陷。问题在设备使用过程中不断暴露出来,对正常生产和设备的稳定运行带来了影响。鉴于以上情况对该油站进行了不断的改造,增加了自力式调压阀;并优化了设备的参数,消除了油站故障和隐患使油站的运行更加稳定。

潮汐电站厂房浮运结构的浮运稳定计算

基于神经网络技术建立了浮运结构的重心知识库和稳性参数知识库 ,用于计算潮汐电站厂房浮运结构在浮运和沉放过程中的稳定性 .该知识库克服了公式计算的局限性 ,无需预知模型的形式 ,建模简单 ,易于程序化 .计算实例表明 。

河流交汇区沉管隧道管节浮运受力特性研究——以广州如意坊沉管隧道工程为例

沉管隧道常被用于城市过江、过河通道工程,明确管节浮运受力特性,对维持沉管隧道稳定性起着至关重要的作用。现有研究多只针对单一内河,其流场较为简单,而对河流交汇区沉管管节浮运受力特性研究较少。文章以广州如意坊沉管隧道工程为依托,采用STAR-CCM+计算流体力学软件构建沉管隧道管节浮运CFD计算模型,计算分析两河交汇区流场特性及管节受力特性。研究结果表明:基槽存在对交汇区流场影响极大;管节左右舷压力分布差距随管节与基槽夹角增大而减小;管节所受阻力随流速增加而增加,横向阻力随夹角增加而减小;管节与基槽夹角越大,管节所受横摇弯矩越小,浮运至河流交汇区时,可以采用与基槽呈大夹角相交的方式浮运。

重力式沉箱码头施工工艺研究应用

为解决重力式沉箱码头在制作、运输和安装施工中的难题,以某新建500 t沉箱重力式客货码头为研究对象,在分析场区地质条件的基础上,研究了重力式沉箱码头各个施工环节的工艺流程,并进行沉降量观测。

全面落实科学发展观，推动公司又好又快发展

当前,贯彻落实党的十七大精神,首要任务就是要用科学发展观来审视我们昕存在的问题,进一步解放思想、改革创新,进一步振奋精神、迎难而上,加快解决制约公司发展的突出矛盾,进一步夯实发展基础、增强发展能力、转变发展模式、提高发展质量,使公司科学发展的步伐更加坚实、道路更加宽广。从公司的现状来看,目前我们工作中存在的差距和不足,突出表现在以下几个方面。

异极式永磁偏置径向磁轴承的建模与实验

为了满足储能飞轮系统、卫星动量轮等对高空间利用率的需求,提出了一种异极式永磁偏置径向磁轴承的拓扑结构。通过在槽口放置平行充磁的永磁体获得紧凑的结构,同时永磁磁路和电励磁磁路耦合距离较短,有利于获取高解耦特性。该文首先采用磁力线法,分别获取考虑齿槽效应、转子偏心的永磁磁场、电励磁磁场的气隙磁通密度分布,建立了磁路模型;然后根据磁路模型求解位移刚度和电流刚度,建立磁轴承的数学模型;与有限元仿真进行对比,证明所建立的磁场模型能够准确计算气隙磁通密度分布。设计、制造一台实验样机并进行相关实验,实验结果验证了磁路模型及有限元仿真的可靠性。

Rigorous back analysis of shear strength parameters of landslide slip

A rigorous back analysis of shear strength parameters of landslide slip was presented. Kinematical element method was adopted to determine factor of safety and critical failure surface, which overcomes the disadvantage of limit equilibrium method. The theoretical relationship between the combination of shear strength parameters and stability state was studied. The results show that the location of critical slip surface, F/tan f and F/c depend only on the value of c/tan f. The failure surface moves towards the inside of slope as c/tan f increases. According to the information involving factor of safety and critical failure surface in a specific cross-section, strength parameters can be back calculated based on the above findings. Three examples were given for demonstrating the validity of the present method. The shear strength parameters obtained by back analysis are almost consistent with their correct solutions or test results.

单壁碳纳米管电子输运特性的稳定性分析

基于变形单壁碳纳米管能量色散关系,计算了碳纳米管最低导带的电子速度及有效质量随形变系数变化的各种曲线,以此推测碳纳米管输运性质的稳定性问题.计算结果表明:对于特定类型的碳纳米管,只当其形变发生在某特定方向、且处于低形变(形变系数ε≤0.02)区时,电子平均速度vmean及平均有效质量mm*ean随形变改变才会很小(相对改变量≤2%),这意味着此时的碳纳米管低偏压电子输运性能是基本稳定的.而其他形变情形,电子平均速度vmean或电子平均有效质量mm*ean或两者随形变变化明显,甚至有跃变,这意味着其低偏压电子输运性能是不稳定的,甚至极不稳定.

Valorization of mining waste and tailings through paste backfilling solution, Imiter operation, Morocco

Mine waste and process tailings storage is one of important challenge for which mining operations are increasingly confronted. Treatment discharges of plants and main part of waste rock development are generally stored on surface areas. The volume and chemical characteristics of these materials generate serious problem for required storage spaces and mainly environmental degradation. Paste backfill(PBF) is one of ingenious solutions to minimize the quantity of tailings to store. PBF is basically defined as a combination of mine processing tailings, binder, and water mixing. The purpose of this paper is to present backfilling components characterization and formula verification for a waste valorization solution through paste backfilling technology in Imiter operation. Obtained results and realized analysis demonstrate PBF conformity and adequacy with assigned underground functions. However the studied recipe can be more ameliorated to obtain an optimal mixture ensuring the required mechanical strength.

A Lifting Line Theory for a Three-dimensional Hydrofoil

Prandtl’s lifting line theory was generalized to the lifting problem of a three-dimensional hydrofoil in the presence of a free surface. Similar to the classical lifting theory, the singularity distribution method was utilized to solve two-dimensional lifting problems for the hydrofoil beneath the free surface at the air-water interface, and a lifting line theory was developed to correct three-dimensional effects of the hydrofoil with a large aspect ratio. Differing from the classical lifting theory, the main focus was on finding the three-dimensional Green function of the free surface induced by the steady motion of a system of horseshoe vortices under the free surface. Finally, numerical examples were given to show the relationship between the lift coefficient and submergence Froude numbers for 2-D and 3-D hydrofoils. If the submergence Froude number is small free surface effect will be significant registered as the increase of lift coefficient. The validity of these approaches was examined in comparison with the results calculated by other methods.

Advances in Technology for Preparation of Acetylene via Partial Oxidation of Natural Gas

This article introduces the latest advances achieved by the Sichuan Vinylon Plant in the fields of maintaining the stable operation of acetylene reactors, extending the operating cycle of production equipment, adaptation to the composition of different natural gas feeds and enlarged scale of production facilities. And a forward-looking idea on next step of technology for manufacture of acetylene from natural gas has been set forth.

Athletes who train on unstable compared to stable surfaces exhibit unique postural control strategies in response to balance perturbations

Background:Athletes have been shown to exhibit better balance compared to non-athletes(NON).However,few studies have investigated how the surface on which athletes train affects the strategies adopted to maintain balance.Two distinct athlete groups who experience different types of sport-specific balance training are stable surface athletes(SSA) such as basketball players and those who train on unstable surfaces(USA) such as surfers.The purpose of this study was to investigate the effects of training surface on dynamic balance in athletes compared to NON.Methods:Eight NON,eight SSA,and eight USA performed five 20-s trials in each of five experimental conditions including a static condition and four dynamic conditions in which the support surface translated in the anteroposterior(AP) or mediolateral(ML) planes using positive or negative feedback paradigms.Approximate entropy(Ap En) and root mean square distance(RMS) of the center of pressure(Co P) were calculated for the AP and ML directions.Four 3 × 5(group × condition) repeated measures ANOVAs were used to determine significant effects of group and condition on variables of interest.Results:USA exhibited smaller Ap En values than SSA in the AP signals while no significant differences were observed in the ML Co P signals.Generally,the negative feedback conditions were associated with significantly greater RMS values than the positive feedback conditions.Conclusion:USA exhibit unique postural strategies compared to SSA.These unique strategies seemingly exhibit a direction-specific attribute and may be associated with divergent motor control strategies.

A Model of Car-Following with Adaptive Headway

The performances of a well-known GHR car-following model was investigated by using numerical simulations in describing the acceleration and deceleration process induced by the motion of a leading car. It is shown that in GHR model vehicle is allowed to run arbitrarily close together if their speed are identical,and it waves aside even though the separation is larger than its desired distance. Based on these investigations, a modified GHR model which features a new nonlinear term which attempts to adjust the inter-vehicle spacing to a certain desired value was proposed accordingly to overcome these deficiencies. In addition, the analysis of the additive nonlinear term and steady-state flow of the new model were studied to prove its rationality.

Chaotic Roll Motions of Ships in Regular Longitudinal Waves

Parametric resonance can lead to dangerously large rolling motions, endangering the ship, cargo and crew. The QR-faetorization method for calculating （LCEs） Lyapunov Characteristic Exponents was introduced; parametric resonance stability of ships in longitudinal waves was then analyzed using LCEs. Then the safe and unsafe regions of target ships were then identified. The results showed that this method can be used to analyze ship stability and to accurately identify safe and unsafe operating conditions for a ship in longitudinal waves.

The design of Three Gorges Hydropower Station

Using physical model and numerical simulation techniques, some technical problems were studied systemati- cally, including layout of power station, measures of sediment and floating debris discharging, types of intake, embed- ded types of spiral ease, layout of underground powerhouse tunnel group and block reinforcement. It was optimal in technique and economy with the arrangement of powerhouse at the dam-toe of both banks ＋ underground powerhouse in the right bank, as well as the intake with a single and small orifice. The sediment and debris problems could be solved with disperse sediment ejection and floating debris discharging holes. With the adoption of techniques for spiral cases such as heat and pressure preservation, cushion layer and combined embedding, the stable operation of generating units can be guaranteed. The arrangement of tailrace tunnel with sloping ceiling was better than that of tailrace surge tank. The technical requirements related to the embedding type of spiral case were proposed. The reinforcement of huge unfavorable blocks was discussed and the new idea for block reinforcement using anti-sliding piles and normal compressive stress of structural plane was put forward.

A pilot study on wastewater treatment by constructed wetlands with high dissolved oxygen vegetated submerged bed

It is necessary to treat wastewater in a more environment-friendly fashion.Vegetated submerge bed constructed wetlands (CWs) has become the focus of the research in this field. In this paper, the overall capacity of vertical subsurface flow CWs in the removal of pollutants from municipal wastewater effluent and the effects of the depth of vegetated submerged bed on the removal efficiency were studied. The results showed that the COD, NH+4-N and TN could be removed effectively in the vertical subsurface flow CWs and the best efficiency was obtained from the 10 cm run. However, the TP removal was not effective in all vertical CWs. A shallow depth of vegetated submerged bed may avoid the risk of substrate plugging effectively, and may keep a stable operation of CWs in long term. Decreasing the depth of vegetated submerged bed could create a sufficient aerobic circumstance in which the concentration of DO (dissolved oxygen) in bed was super saturation.

Automatic HAZOP analysis method for unsteady operation in chemical based on qualitative simulation and inference

Comparing with continuous production process, unsteady operation process, such as startup and shutdown,tends to abnormal situations due to a large number of operations of operators and dynamic state changes involved. To guarantee a safe operation, process hazard analysis(PHA) is very important to proactively identify the potential safety problems. In the chemical process industry, hazard and operability(HAZOP) analysis is the most widely used method. In this paper, based on proposed qualitative simulation and inference method, an automatic HAZOP analysis method for unsteady operation processes is proposed. Mass transfer and relationships among process variables are expressed by Petri net–directed graph model based fuzzy logic. Operating procedure is expressed according to a formal expression. Possible operation deviations from normal operating procedure are identified by using a group of guidewords. Hazards are identified automatically by qualitative simulation and inference when wrong operation process is performed. The method is validated by a rectification column system.

Influences of different diluents on ignition delay of syngas at gas turbine conditions：A numerical study

Ignition delay of syngas is an important factor that affects stable operation of combustor and adding diluents to syngas can reduce NO_x emission.This paper used H_2O,CO_2 and N_2 as diluents and calculated ignition delay of syngas in temperature range of 900-1400 K and at pressures of 10 and 30 atm respectively.In high temperature range,comparing with N_2 dilution,adding H_2O and CO_2 can significantly inhibit autoignition of syngas because they have higher collision efficiencies in reaction H + O_2(+ M) = HO_2(+ M).As for low temperature conditions,adding H_2O can increase reactivity of syngas,especially under high pressure,because of its high collision efficiency in reaction H_2O_2(+ M) = 2OH(+ M).Comparing with different dilution rates shows that for syngas and operating conditions in this paper,adding N_2 mainly influences temperature rising process of syngas combustion,thus inhibiting reactivity of syngas.In addition,this paper calculated ignition delay of syngas at different equivalence ratios(φ= 0.5,1.0).Higher equivalence ratio(φ≤1) means that less air(especially N_2) needs to be heated,thus promoting ignition of syngas,

Stability analysis via the concept of Lyapunov exponents―a case study

The dynamics characteristics of the robotic arm system are usually highly nonlinear and strongly coupling,which will make it difficult to analyze the stability by the methods of solving kinetic equations or constructing Lyapunov function,especially,these methods cannot calculate the quantitative relationship between mechanical structures or control input and dynamics parameters and stability.The theoretical analysis process from symbol dynamics modeling of the robotic arm system to the movement stability is studied by using the concept of Lyapunov exponents method. To verify the algorithm effectiveness,the inner relation between its joint input torque and stability or chaotic and stable motion of the 2-DOF robotic arm system is analyzed quantitatively. As compared with its counterpart of Lyapunov's direct method,the main advantage of the concept of Lyapunov exponents is that the methods for calculating the exponents are constructive to provide an effective analysis tool for analyzing robotic arm system movement stability of nonlinear systems.

Characteristics and stability of slope movement response to underground mining of shallow coal seams away from gullies

Underground pressure is abnormal during mining of shallow coal seams under gullies. We studied gully slope movements, subject to underground mining, with physical simulation and theoretical analysis. The rules disclose that the slope rock slides horizontally in response to mining in the direction of gullies and rotates reversely with the appearance of a polygon block in mining away from gullies. We focused our attention on the case of mining away from a gully. We built a mechanical model in terms of a polygon block hinged structure and investigated the variation of horizontal thrust and shear force at the hinged point in relation to the rotation angle under different fragmentations. The Sliding-Rotation instability conditions of the polygon block hinged structure are presented based on the analyses of sliding instability and rotation instability. These results can serve as a theoretical guide for roof control during mining away from gullies in a coalfield defined by gullies.