空调器中多翼离心风机的噪声研究及结构优化

采用逐步回归法对大量的多翼离心风机实验数据进行拟合,针对家用空调行业中以噪声为其最重要 的考核标准,得出了噪声与叶轮结构参数及风机性能参数间的近似关系式,并以噪声为目标函数进行了优化计算。     

A Theoretical Framework for Core Material Properties Identification in Cellular Solids using Novelty Detection

Abstract:  This paper presents a novelty detection-based technique to identify core material properties of honeycombs and cellular structures. A numerical model (finite element) representing full scale and/or reduced size of the cellular solid is used to generate transmissibilities between topological homologous points at cells in different locations. In order to make the procedure robust against noise, these transmissibilities are artificially corrupted. This step is representative of a series of experimentally obtained measurements which automatically return information relating to the size and shape of data noise along with the mean measurement. The next stage, both in this paper and in the proposal for the experimental approach, is to generate several further sets of transmissibilities from the finite element model; the only difference being that the core material properties are altered from the original values. A novelty detection framework is then adopted to find a similarity measure between each of these 'test' transmissibilities and the original set thereby identifying the material properties. Although this work is concerned with identifying only one material property, the methodology extends to identifying several properties.     

盐井水平对接钻井技术

钻一口通过主采盐层的水平井与已完成的直井对接，形成连通井(形如“U”字)，一口井注水溶解盐／芒硝矿，另一口井采出卤水，这是盐化工业对钻井提出的要求。针对水平对接盐井井身轨迹设计、着陆段、水平段的轨迹控制和连通技术，介绍了水平段侧钻时的钻井液技术。     

KMLS型立式砂泵的振动噪声产生原因及解决措施

针对KMLS型立式砂泵振动、噪声产生原因及其表现特征,提出了解决措施。通过对这些原因的分析研究,可以提供泵设计者和生产者在减少砂泵振动方面采取相应的措施,使KMLS型立式砂泵能更好的服务于用户。     

Termites live in a material world: exploration of their ability to differentiate between food sources.

Drywood termites are able to assess wood size using vibratory signals, although the exact mechanism behind this assessment ability is not known. Important vibratory characteristics such as the modal frequencies of a wooden block depend on its geometry and boundary conditions; however, they are also dependent on the material characteristics of the block, such as mass, density and internal damping. We report here on choice experiments that tested the ability of the drywood termite Cryptotermes secundus to assess wooden block size using a solid wooden block paired with a composite block, the latter made of either wood and aluminium or wood and rubber. Each composite block was constructed to match mass or low-frequency vibratory modes (i.e. fundamental frequency) of the solid wooden block. The termites always chose the blocks with more wood; they moved to the solid wooden blocks usually within a day and then tunnelled further into the solid wooden block by the end of the experiment. Termites offered composite blocks of wood and rubber matched for mass were the slowest to show a preference for the solid wooden block and this preference was the least definitive of any treatment, which indicated that mass and/or damping may play a role in food assessment. This result clearly shows that the termites were not fooled by composite blocks matched for mass or frequency, which implies that they probably employ more than a single simple measure in their food assessment strategy. This implies a degree of sophistication in their ability to assess their environment hitherto unknown. The potential importance of alternative features in the vibrational signals is discussed.     

钻井液振动筛叠层筛网透筛率的研究

从理论上详细论述了钻井液振动筛叠层筛网对固相颗粒分离的影响 ,首次提出用透筛率的概念定量地描述这一影响 ,并进行了实例计算。研究表明 ,当上下层筛网随机叠加时对透筛率的影响有以下几种情况 :(1)当上下层筛网开孔尺寸相除的余数为零 ,任意组合叠层筛网的透筛率分别为某一常数 ;(2 )上层筛网目数一定时 ,下层筛网目数越大 ,则透筛率越小 ;(3)上下层筛网的目数相差越小 ,透筛率越小 ;(4 )任意目数的上下层筛网随机叠加后 ,其透筛率仅在一个小范围内变化 ,因此任一叠层筛网有其固有的透筛率属性。     

往复式压缩机管道的防振设计

分析了往复式压缩机管道产生振动的原因及影响因素,提出解决管道振动的方法及对策。     

非线性隔振理论初探

本文以线必阻尼，立方刚度非线性系统为例，对非线性隔振理论进行了初步探讨，导出了系统的无量纲运动响应和传递率，并与线性隔振系统进行了比较，着重讨论了非线性对它们的影响，获得了一些有用的结论。     

柔性冗余度机器人残余振动主动控制

研究柔性冗余度机器人的残余振动主动控制问题，设计了具有压电作动器与应变传感器的机敏杆件，建立了受控系统的状态空间表达式，采用独立模态空间控制理论设计LQR状态反馈控制器，并基于对偶原理设计了具有指定收敛特性的Luenberger全维状态观测器，最后，以平面3R柔性冗余度机器人为例进行了计算机仿真，结果表明，采用这种主动控制方法可以显著改善柔性冗余度机器人的动力学品质。     

Response level crossing rate of a linear system excited by a partially specified Gaussian load process

The problem of determining the maximum mean response level crossing rate of a linear system driven by a partially specified Gaussian load process has been considered. The partial specification of the load is given only in terms of its total average energy. The critical input power spectral (PSD) function, which maximizes the mean response level crossing rate, is obtained. The critical input PSD turns out to be highly narrow-banded which fails to capture the erratic nature of the excitation. Consequently, the trade-off curve between the maximum mean response level crossing rate and the maximum disorder in the input process, quantified in terms of its entropy rate, has been generated. The method of Pareto optimization is used to tackle the conflicting objectives of the simultaneous maximization of the mean response level crossing rate and the input entropy rate. The non-linear multi-objective optimization has been carried out using a recently developed multi-criteria genetic algorithm scheme. Illustrative example of determining the critical input of an axially vibrating rod, excited by a partially specified stationary Gaussian load process, has been considered.