二次加压泵站的运行调节及节能分析

加压泵站是现阶段我国供水系统的重要环节,通过分级加压可以实现水泵变频调速恒压变流供水,水泵全速节流供水以及直连变频调整变压变流供水等加压泵站的运行调节。通过研究二次加压泵站的运行调节的原理,可以明确其能耗状况,综合分析调节效果和能源的消耗,可以找出综合利用价值最高的节能供水技术,促进我国自来水管网的完善,减少二次污染的出现。针对于此,本文就二次加压泵站的运行调节方式和节能策略进行分析。     

采用液压变压器原理的液压电梯节能系统设计

介绍了一种新型节能液压电梯泵站系统的设计流程，给出了详细的设计步骤和方法，通过较精确的计算，得出了一种装机功率很小的液压电梯节能泵站系统。     

试论管网叠压供水在丘陵地区乡村供水的实践

叠压供水技术，实际上也被称为无负荷供水技术，该技术是我国市政管网供水体系的设计施工中所常用的一项技术。叠压供水技术相对其他供水技术，具有更好的节能性、经济性等优势，并且有效解决了传统供水技术中所存在的二次污染问题，促使城市居民的用水质量有所提升，叠压供水技术有着良好的发展前景，值得大范围进行推广。东南沿海丘陵地带村庄分散，地形崎岖，供水设施落后，供水安全不稳定。本文介绍了平潭农村供水管网叠压式供水的应用，结合当地的地理环境及特征，探讨了管网叠压式泵站的形式、设计，以期为我国农村供水管网叠压式的应用提供借鉴。     

基于PLC的恒压供水系统设计

介绍了住宅小区供水泵站的恒压控制系统,采用PLC作为控制器,变频器自动调节供水压力。在加泵和减泵过程的设计中采用一种新的切换方法,在实际应用中得到了很好的效果。系统具有压力稳定、结构简单、工作可靠等特点,不仅满足了供水的要求,而且达到了节能的目的。     

混合遗传算法在泵站优化运行中的应用

泵站，特别是连续供水的给水泵站耗能很大．因此提高泵站运行效率、安全供水具有重大的现实意义。本文分析了遗传算法的优缺点，引入与之互补的Rosenbrock算法，构造了混合遗传算法的数学模型．并将其用于泵系统的变速调节优化运行。与传统的优化算法比较，取得了较好的优化结果。     

基于目标电耗的城镇供水泵机组节能技术的研究及应用

针对供水输送系统由于水泵选型不当、工况调节不合理、能耗评估困难等原因造成运行效率低、能耗浪费严重的问题,以某城镇供水泵站为研究对象,通过分析供水系统设备安装情况和生产周期内泵的运行工况,以能耗系数为评估指标,建立一套通过检测管网关键运行工况点,绘制泵的实际运行外特性曲线,来分析泵机组能耗原因,比较改造前后系统总KE—Q方程,得出系统节能空间的方法。实际改造方案以"大小泵阶梯搭配"和"同型号泵+一泵变频"两方案进行节能空间与改造投资成本分析,确定"大小泵阶梯搭配"组合运行为最佳改造方案。改造后测试结果表明,供水泵机组月节电12850 kW·h,系统节电率19.58%,为其它城镇供水泵站节能改造提供借鉴。     

泵站可靠性设计中应注意的几个问题

泵站设计要考虑用户对可靠性的要求程度，同时选择可靠设备，保证泵站供水可靠，满足用户要求。     

高尔夫球场灌溉系统用泵站

高尔夫球场灌溉系统要求泵站恒压供水。该恒压供水泵站包括:泵、电动机、管路、阀门、过滤器和控制系统。变频控制系统是泵站的心脏。高尔夫球场的建造者在选购泵站时需考虑球场供电、供水现状、球场前期投资和后期运行、维护的综合费用。     

泵站绕线式异步电机进相运行研究及应用

根据绕线式异步电机结构，结合排灌泵站的运行特点，论证了转子激磁进相运行节能机理，为泵站节能技术开发提供了理论依据。     

变频器在给水工程中节能降耗的分析

本文在实现莱二级泵站给水系统变频调速控制的基础上,利用离心泵的特性曲线扣供水管网的阻力曲线分析了该给水系统节能降耗的原理,给出了该系统的构成和工作原理,并根据节能降耗原理进行节能效果的分析,说明该系统结构合理,节能降耗效果明显。     

Effects of prebuckling deformations on the elastic flexural-torsional buckling of laterally fixed arches

The effect of the prebuckling in-plane deformations on the elastic flexural-torsional buckling of laterally fixed circular arches is studied in this paper. The finite strains and the energy equation for the flexural-torsional buckling of arches have been derived based on an accurate orthogonal rotation matrix. A closed form solution for the elastic flexural-torsional buckling resistance of laterally fixed arches in uniform bending, including the effects of the prebuckling deformations, is obtained. It is found that the notion that the prebuckling deformations increase the flexural-torsional buckling moment of an arch or of a beam is not necessarily correct for a laterally fixed arch or beam in uniform bending, in deference to a laterally pinned arch. When a laterally fixed arch is subjected to positive uniform bending, the effects of the prebuckling deformations decrease the buckling moment, and the reduction of the buckling moment increases with an increase of the included angle and of the out-of-plane slenderness ratio of the arch. When a laterally fixed arch is subjected to negative uniform bending, the effects of the prebuckling deformations decrease the absolute value of its buckling moment when the included angle is very small, but increase the absolute value of the buckling moment when the included angle exceeds a certain value. The increase in the absolute value of the buckling moment increases with an increase of the included angle and of the out-of-plane slenderness ratio of the arch. When the ratio of the out-of-plane to the in-plane second moments of area of the cross-section is not small, both the reduction of the buckling moment of a laterally fixed arch in positive uniform bending and the increase of the buckling moment of a laterally fixed arch in negative uniform bending, are substantial.     

PHENOMENON OF CARVED DRIVING WHEELS

A newly found phenomenon of carved driving wheels of a rear-wheel-drive tractor used in an airport is discussed. The circum of every driving wheel is damaged at three regions,which distribute regularly and uniformly. Everyday,the tractor tows a trailer which are times heavier than the tractor,and moves on the same road in the airport. The phenomenon is explained by the torsional self-excited vibration system of the powertrain. The simplified torsional vibration system is discribed by a 2-order ordinary differential equation,which has a limit circle. Experiments and numerical simulations show the followings: Because of the heavy trailer,the slip ratio of the tractor’s driving wheels is very large. Therefore,there is severe torsional self-excited vibration in the tractor’s drivetrain,and the self-excited vibration results in severe and regular fluctuations of the rear wheel’s velocity. The severe fluctuations in velocity fastens the damage of the driving wheels. At the same time,the time interval in which an arbitrary point in the circum of the driving wheel contacts with the road twice is two times more than the period of the torsional self-excited vibration,and this times explained the existence of three damaged regions. At last,it points out that the phenomenon can be avoided when the torsional damping is large enough.     

DESIGN AND CAD SYSTEM OF THE FOOL FOR DRILL FLUTE

Based on the principles of differential geometry and kinematics, a mathematical model is developed to describe the grinding wheel axial cross-section with the radial cross-section of the flute in a given drill under the basic engagement condition between the generating flute and the generated grinding wheel (or disk milling tool). The mathematical model is good for the flute in the radial cross-section consisting of three arcs. Furthermore, a CAD system is also developed to represent the axial cross-section of the grinding wheel (or disk milling tool). With the system, the grinding wheel (or disk milling tool) axial cross-section that corresponds to the three-arc flute cross section can be conveniently simulated. Through the grinding experiment of drill flutes, the method and the CAD system are proved to be feasible and reasonable.     

孔隙阀式磁流变阻尼器准静力分析

建立了孔隙阀式磁流变阻尼器的轴对称模型.推导了孔隙阀内磁流变液压力梯度方程.对Herschel-Bulkley模型的磁流变阻尼器压力梯度进行了数值求解.应用代数方程理论,得到了Bingham模型的磁流变阻尼器压力梯度的解析解.最后,结合算例计算了孔隙阀内磁流变液的流速分布及阻尼器的阻尼力.     

车门静态强度的有限元分析模拟

轿车门系统结构设计与优化是整车开发过程中的重要环节。车门的强度直接关系到整车在冲击、碰撞等载荷下的安全问题,车门结构静态强度的计算分析,在车门结构设计进程中非常重要。文中首先简要介绍了静态强度所涉及到的非线性有限元的基本理论,然后以某中高级轿车前车门为例,利用计算机辅助分析车门的静态强度,考虑变形的非线性因素,通过对车门的非线性有限元求解来分析车门强度,由计算所得到的车门强度性能指标来指导车门的结构设计。     

气化炉三维扫描测量与数据处理

以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可.     

OPTIMIZING DESIGN OF MECHANICAL SELF-CENTERING DEVICE FOR SUSPENSION HEIGHT

Firstly, in view of the respective defects of existing self-centering devices for vehicle suspension height, the design scheme of the proposed mechanical self-centering device for suspension height is described. Taking the rear suspension of a certain light bus as a research example, the structures and parameters of the novel device are designed and ascertained. Then, the road excitation models, the performance evaluation indexes and the half-vehicle model are built, the simulation outputs of time and frequency domain are obtained with the road excitations of random and pulse by using MATLAB/Simulink software. So the main characteristics of the self-centering suspension are presented preliminarily. Finally, a multi-objective parameter design optimization model for the self-centering device is built by weighted sum approach, and optimal solution is obtained by adopting complex approach. The relevant choosing-type parameters for self-centering device components are deduced by using discrete variable optimal method, and the optimal results are verified and analyzed. So the performance potentials of the self-centering device are exerted fully in condition of ensuring overall suspension performances.     

IMPROVED METHOD FOR HILBERT INSTANTANEOUS FREQUENCY ESTIMATION

In the mechanical fault detection and diagnosis field, it is more and more important to analyze the instantaneous frequency (IF) character of complex vibration signal. The improved IF estimation method is put forward aiming at the shortage of traditional Hilbert transform. It is based on Hilbert transform in wavelet domain. With the help of relationship between the real part and the imaginary part obtained from the complex coefficient of continuous wavelet transform or the analytical signal reconstructed in wavelet packet decomposition, the instantaneous phase function of the subcomponent is extracted. In order to improve the precise of IF estimated out, some means such as Linear regression, adaptive filtering, resampling are applied into the instantaneous phase obtained, then, the central differencing operator is used to get desired IF. Simulation results with synthetic and gearbox fault signals are included to illustrate the proposed method.     

The effect of basic nitrogen compounds on the tribological performance of sulphurised olefin

The effect of the molecular structure of basic nitrogen compounds on the lubricating properties of sulphurised olefin has been investigated using a Timken tester. X-ray Photoelectron Spectroscopy (XPS) and Energy Dispersive X-ray Analysis (EDAX) were used to study the chemical states of sulphur and nitrogen on the rubbed surfaces and the reaction rates of sulphur and iron separately. It was found that the antiwear and friction reduction properties of sulphurised olefin are greatly influenced by the different molecular structures of the basic nitrogen compounds. A composite additive package containing basic nitrogen compounds with sulphurised olefin can produce either synergistic or antagonistic effects, due to the influence of the different molecular structures of the basic nitrogen compounds. XPS analysis revealed that a tribochemical protective film containing nitrogen and sulphur was formed on the rubbed surface. EDAX analysis indicated that the reaction rates between elemental sulphur and iron were influenced by the different molecular structures of the basic nitrogen compounds. It was found that the apparent reaction rates of elemental sulphur and iron are related to the tribological characteristics of the additive package.     

Adaptive stochastic resonance method for weak signal detection based on particle swarm optimization

In order to solve the parameter adjustment problems of adaptive stochastic resonance system in the areas of weak signal detection,this article presents a new method to enhance the detection efficiency and availability in the system of two-dimensional Duffing based on particle swarm optimization.First,the influence of different parameters on the detection performance is analyzed respectively.The correlation between parameter adjustment and stochastic resonance effect is also discussed and converted to the problem of multi-parameter optimization.Second,the experiments including typical system and sea clutter data are conducted to verify the effect of the proposed method.Results show that the proposed method is highly effective to detect weak signal from chaotic background,and enhance the output SNR greatly.