Cylinder pressure based combustion phase optimization and control in spark-ignited engines

Efficiency and emissions of spark-ignited engines are significantly affected by combustion phase which can usually be indicated by crank angle of 50\% mass burnt (CA50). Managing combustion phase at the optimal value at which the maximal efficiency can be achieved is a challenging issue due to the cyclic variations of combustion process. This paper addresses this issue in two loops: CA50 set-point optimization (outer loop) and set-point tracking (inner loop) by controlling spark advance (SA). Extremum seeking approach maximizing thermal efficiency is employed in the CA50 set-point optimization. A proportional-integral (PI) controller is adopted to make the moving average value of CA50 tracking the optimal CA50 set-point determined in the outer loop. Moreover, in order to obtain fast responses at steady and transient operations, feed-forward maps are designed for extremum seeking controller and PI controller, respectively. Finally, experimental validations are conducted on a six-cylinder gasoline at steady and transient operations to show the effectiveness of proposed control scheme.     

雅砻江锦屏一级水电站筒形阀安装工艺研究

锦屏一级水电站单机的装机容量为600 MW,其机组上装设的直径为8 750 mm的筒形阀是目前国内已运行电站中直径大、重量重、水头最高的电液数字液压伺服控制器同步筒形阀。详细介绍了该电站筒形阀的结构特点及其安装工艺,以及在安装过程中的重点和难点。通过锦屏一级水电站筒形阀安装,总结了水电站筒形阀安装工艺及其技术控制措施,以期为后续水电站类似阀的设计、安装以及调试等工序提供借鉴。     

回转窑烧成带镁铬砖的使用与窑衬寿命的关系

根据回转窑烧成带镁铬砖的损坏机理，找出提高窑衬周期的具体措施，阐明水泥生产过程中回转窑烧成带镁铬砖的使用与窑衬寿命的关系。     

合金铸铁缸体的电泳涂装设计

本从生产线设计、设备制造等方面对涪陵柴油机厂的合金铸铁缸涂装工艺进行彻底改造，降低了生产成本，提高了生产效率和产品质量。     

填埋场衬垫系统的评价

城市固体废弃物填埋场是许多国家最终处置固体废弃物的主要方法,其衬垫系统是填埋场整个系统中最关键的部位。主要介绍了填埋场衬垫系统的发展及其3种主要衬垫材料,并对三者进行了互比较,指出使用GCL是未来衬垫系统材料应用的发展方向。但由于经济和效益之间的矛盾,使得能否真正实施符合高标准高要求的衬垫系统成为我国当前填埋技术中的突出问题。结合我国国情,指出在选择和设计衬垫系统时应因地制宜,切合实际,建造有地方特色的垃圾填埋场。最后,对衬垫干裂、衬垫厚度以及衬垫系统中的稳定性等问题进行了讨论。     

Numerical simulation of the current, potential and concentration distributions along the cathode of a rotating cylinder Hull cell

Numerical simulations of the non-uniform current, potential and concentration distributions along the cathode of a rotating cylinder Hull (RCH) cell (RotaHull^® cell) are performed using finite element methods. Copper electrodeposition from an acid sulfate electrolyte is used as a test system. Primary, secondary and tertiary current distributions are examined. The importance of controllable and uniformly accessible hydrodynamics along the length of the RCH cathode is demonstrated. Charge transfer kinetics are described by a Tafel approximation while mass transport is considered using a Nernstian diffusion layer expression. The effects of applied current density and electrode rotation speeds on the distribution of potential and current along the RCH cathode are investigated. An expression of the primary current distribution and a dimensionless mass transport correlation facilitate comparisons with the simulations.     

橡胶衬板在云浮硫铁矿自磨工艺中的应用

橡胶衬板代替传统的磨矿机锰钢衬板的工业性试验表明,橡胶衬板在延长使用寿命、改善磨矿机电机工作状况、减少磨矿机噪音和提高经济效益等方面具有明显的效果     

GENERALIZED FINITE DIFFERENCE SOLUTION FOR HEAT AND MASS TRANSFER FROM A FINITE CYLINDER DURING QUENCH

A generalized nondimensional solution is presented that describes heat or mass transfer from a finite cylinder during quench. The solution is applicable to three important cases:

Conduction with convection heat transfer at the surface during any single step hot or cold quench.

Conduction with radiation heat transfer at the surface during a single step cold quench with negligible background radiation.

Diffusion with surface desorption of a diatomic gas from a metal specimen during a single step quench in a high vacuum with negligible background pressure.

Application of the generalized solution, which utilizes the numerical method of finite differences with forward stepping, is illustrated by determining a cylinder's transient temperature distribution and surface transfer rate (both instantaneous and cumulative) for an example L/D ratio of 2.0. Selected results are graphed and tabulated for the three cases. The results for the conduction/convection case are verified using the familiar analytical product solution as well as the lumped solution. For the conduction/radiation and diffusion/desorption cases, no analytical solutions are available other than the lumped limit which is in agreement.     

Removal of cadmium and production of cadmium powder using a continuous undivided electrochemical reactor with a rotating cylinder electrode

The behaviour of a continuous undivided electrochemical reactor with a rotating cylinder electrode under potentiostatic control is examined for the abatement of cadmium from synthetic sodium sulfate solutions with Cd(II) concentrations lower than 500 mg dm^?3 at a reactor inlet pH ? 7. The process was designed to convert the metal ions in solution to metal powder, which settles to the conical of the reactor and may be removed at intervals as a sludge by opening a drop valve. The effect of applied potential, inlet cadmium concentration, rotation speed and hydrogen evolution as side cathodic reaction on the ‘figures of merit’ of the reactor are analysed. The best results were obtained for cathode potentials in the range from ?0.9 V to ?1.0 V against the saturated calomel electrode. Therefore, when the rotation speed was 1000 rpm the space time yield and the normalized space velocity were 0.64 ×10^?2 mol m^?3 s^?1 and 0.89 h^?1 respectively, while the fractional conversion per pass was 35% with a current efficiency higher than 74%. The surface morphology of the deposits as a function of the process variables is also reported. © 2002 Society of Chemical Industry     

节流阀出口节流调速系统动态特性研究

在节流阀出口节流调速系统中,负载的变化特别是阶跃变化,液压缸两腔压力会发生动态变化,使活塞（杆）的速度产生波动,甚至引起系统中液压元件损坏,影响液压系统的正常工作。以负载作为输入,液压缸有杆腔和无杆腔压力作为输出分别建立系统的数学模型,得到了液压缸两腔压力超调量的变化规律,并利用压力传感器测量了压力超调量的变化,通过试验对理论分析进行了验证,试验数据与理论分析相吻合,利用系统液压缸两腔压力动态变化规律,修正了液压元件主参数（额定压力）选择的计算公式,为系统设计以及元件参数选择提供依据。