剪式液压升降台相关参数的确定

设计剪式液压升降台要解决的关键问题,是科学、合理地确定液压缸的有效行程及其它结构参数.液压缸的有效行程受各结构参数的影响,而这些参数又影响液压缸的受力,各参数之间的关系错综复杂.要设计出液压缸受力小,而又能满足运动要求的剪式液压升降台,必须明确各参数之间的相互关系,进行综合分析.通过分析剪式液压升降台的运动过程,推导出了满足升降台升降的相关参数的关系式;通过分析和比较升降台在负重上升过程中液压缸推力的变化规律,确定了铰架仰角a的取值范围、液压缸的有效行程及有关结构参数的取值规律,为升降台的系列设计提供了理论依据.     

Model-based design of horizontal subsurface flow constructed treatment wetlands: a review

The increasing application of constructed wetlands for wastewater treatment coupled with increasingly strict water quality standards is an ever growing incentive for the development of better process design tools. This paper reviews design models for horizontal subsurface flow constructed treatment wetlands, ranging from simple rules of thumb and regression equations, to the well-known first-order k-C* models, Monod-type equations and more complex dynamic, compartmental models. Especially highlighted in this review are the model constraints and parameter uncertainty. A case study has been used to demonstrate the model output variability and to unravel whether or not more complex but also less manageable models offer a significant advantage to the designer.     

Seismic response analysis of structures with velocity-dependent dampers

This paper is concerned with seismic response analysis of structures with velocity-dependent passive energy dissipation devices, such as viscous and viscoelastic dampers. The modeling of a damper-brace component composed of a viscous or viscoelastic damper connecting with braces in series is presented. Several key parameters influencing the energy dissipation efficiency of such dampers in the damper-brace component are investigated and the relationships of the parameters and efficiency of the dampers are established. An equivalent model for the passive energy dissipation system is developed, which can significantly simplify the dynamic analysis of structures with the velocity-dependent dampers. The seismic responses of a single-story structure and a multi-story structure with the viscous and viscoelastic dampers are analyzed to verify the effectiveness of the passive energy dissipation devices for suppression of dynamic responses of structures and the reliability of the proposed simplified computational methods.     

Respirometric calibration and validation of a biological nitrite oxidation model including biomass growth and substrate inhibition

The modelling of the nitrification process of high-strength ammonium wastewater must be designed to consider it as a two-step reaction with substrate inhibition. Consequently, kinetic and stoichiometric parameters of both steps are required. In this work, the second step in the nitrification process was studied: a biological nitrite oxidation model was formulated, calibrated and validated using only oxygen uptake rate (OUR) measurements. The model included biomass growth and substrate inhibition. First, the biomass yield coefficient for nitrite-oxidising biomass was determined. Then, a respirometric experiment with one nitrite pulse of 500 mg N-NO₂⁻ L⁻¹ was performed to estimate the rest of the model parameters. The practical identifiability study showed that the parameters were strongly correlated. Hence, a new experimental design consisting of two consecutive pulses and a delayed third one was designed to improve the parameter identifiability. Both experimental designs were compared using contour plots of the objective function and optimal experimental design criteria for parameter estimation. It was concluded that the parameter identifiability was improved with the new experimental design. Finally, the estimated parameters were validated and the pH effect on the inhibition coefficient was evaluated.     

单斗液压挖掘机系列主参数规律的研究

本文应用设计方法学关于系列产品开发的策略，讨论了单液压挖掘机系列型谱的判定依据，研究主参数系列化的规律，以此来确定斗容量范围及发动功率。     

石英音叉陀螺误差分析

从理论上分析了石英音叉陀螺仪的几种主要误差源:电容耦合、机械耦合和驱动力耦合,分别建立了这几种误差源的物理模型,并推导了各种误差源的计算公式.通过实例计算,得到了各项误差的影响强度.将计算结果与样机的实测值进行比较,两者基本吻合,从而证明了石英音叉陀螺误差源模型是合理的.     

基于多新息最小二乘算法的电力线路参数辨识

随着电力系统的建设和发展,电网结构日益复杂,由于线路长期运行、周围环境变化等原因导致原有的线路参数模型与实际线路参数存在偏差,从而影响电力系统的实时监控和优化运行。考虑到电力系统输电线路中的数据采集与监控(SCADA)系统量测充足,提出基于多新息最小二乘(MILS)算法的线路参数辨识模型,实现全网线路的准确辨识和校正。首先,利用实时数字仿真(RTDS)系统搭建IEEE 39节点电力系统仿真模型,获得潮流运行数据;然后,在Matlab中进行参数辨识,将辨识结果与RTDS中的线路参数进行对比。结果表明,基于MILS算法的参数辨识结果具有较高估计精度,可作为电力系统可疑线路判断依据。     

NGB-W广播信道估计实现算法设计

针对下一代广播电视网无线系统(NGB-W)广播接收信道估计,提出了一种基于二次一维维纳滤波的信道估计实用算法.该算法实时估计信道多普勒频偏、时延扩展和噪声方差等参数,并根据参数估计值分别从离线获得的预选集中选择时域和频域的一维维纳滤波系数.通过Cocentric System Studio(CCSS)平台仿真,给出了参数估计对算法性能的影响,以及所提信道估计算法的均方误差和误块率性能.仿真结果表明该算法在不同移动速度下,与采用理想插值系数信道估计相比性能损失不超过0.4 dB,与理想信道估计相比性能损失在1 dB以内.     

电动助力转向系统性能仿真研究

针对电动助力转向研究通常忽略控制策略对转向系统的影响,整车与转向系统之间是相互联系的问题,采用模糊PID控制和Carsim-Simulink联合仿真方法,在建立电动助力转向系统模型的基础上,根据不同工况下不同控制模式的需求,提出了多模式控制策略,应用模糊PID控制设计了电机电流控制器模型,并建立Carsim-Simulink联合仿真模型。仿真结果表明,建立的仿真模型是有效的,且所设计的控制策略能满足系统要求。