阀笼式调节阀套筒窗口形状设计与流量特性分析

我国的阀笼式调节阀技术起步晚,传统的设计过程常常依赖经验公式,产品的实验结果与设计要求存在较大误差。因此,以阀笼式调节阀套筒为设计对象,基于阀笼式调节阀的孔板流量计原理,推导得到套筒横截面积的通用公式和4种流量特性(直线型流量特性、等百分比型流量特性、抛物线型流量特性和快开型流量特性)不同开度下套筒的横截面积,建立模型并用FLUENT软件进行仿真模拟,将调节阀在不同开度下相对流量的实验值与理想设计值进行对比。结果表明:此设计方法在调节阀开度为30%～80%时具有可靠性,不仅有效满足设计要求,而且该方法设计周期短、成本低、精度高。此外,通过推导的阀笼式调节阀套筒的通用面积公式,可改变套筒进口处和出口处的压力值和不同固有流量特性要求,得到符合特定要求的套筒,故具有一定的工程应用价值。     

机电液系统转速波动分量Vold-Kalman时变滤波提取方法

机电液系统的转速波动信号蕴含着丰富的系统运行状态信息,从该转速波动信号中通常可以观测到多个波动源的耦合现象。针对磁电式转速传感器输出的方波信号中转速波动分量的特征提取问题,提出了基于Vold-Kalman时变滤波的转速波动分量提取方法。首先利用采样点计数测速算法获得变转速泵控液压马达系统的瞬时转速信号;其次,结合短时傅立叶变换和二值细化处理得到的瞬时频率估计曲线作为中心频率,构造了基于转速波动信号特征模型的结构方程和数据方程;最后通过最小二乘滤波和PCG法求解,实现了转速波动分量时域波形的提取。实验结果表明:该方法能有效地提取变转速泵控马达系统中由柱塞马达输出轴转频及减速箱输出轴转频引起的转速波动,为机电液系统的状态监测和运行可靠性分析提供了新方法。     

雷达探测数据野值剔除方法

为提升雷达探测精度评估中雷达探测导弹目标数据的质量,提出基于滑窗的均值和中值剔除法,并将其 与基于滑窗的多项式拟合法和模板卷积法进行对比分析。通过以3 倍的均方误差作为门限,设置合适的窗口长度, 选取基于窗口滑动的均值或中值剔除法。测试结果表明：2 种方法均可更有效地剔除雷达探测导弹目标数据中的野 值,为后续弹道还原和数据评估提供了有效支撑。     

高层建筑如何防止窗扇坠落

窗户是城市中的眼睛,人们在追求建筑质量的同时对窗户的功能性要求也越来越高。但是对于高层而言,有些窗型还是不适合运用的。因此,合理地选择窗型能有效地减免或控制窗扇事故的发生。     

变负荷机组锅炉经济连续排污流量的确定

通过开展变负荷机组的热化学实验，监督不同负荷工况下的汽水品质，确定较为经济的锅炉连续排污流量，对产生的效益进行了分析和计算。     

Lower limit law of welding windows for explosive welding of dissimilar metals

The influence of explosive charge thickness on the quality of explosive welding of dissimilar metals was in-vestigated.The lower limit law should be followed in the course of explosive welding.Three welding ex-periments of stainless steel (410S) and steel (Q345R) were carried out in three different kinds of explo-sive charge thicknesses, namely 15, 25 and 35 mm.Interfaces of morphology and mechanical properties of three samples were observed and tested.It was found that micro and small wavy bonding is mainly formed for charge thickness of 15 mm whose strength is the highest with minor deformation and few defects in the interface; small and middle wavy bonding are mainly formed for charge thickness of 25 mm whose strength is comparatively mediocre; big wavy bonding is mainly formed for charge thickness of 35 mm whose strength is the lowest.The cause of high bonding strength of the micro and small wavy interface was analyzed and verified on the basis of the results of Electron Probe Micro-Analyzer (EPMA) tests of three selected samples.     

A new content-defined chunking algorithm for data deduplication in cloud storage

Chunking is a process to split a file into smaller files called chunks. In some applications, such as remote data compression, data synchronization, and data deduplication, chunking is important because it determines the duplicate detection performance of the system. Content-defined chunking (CDC) is a method to split files into variable length chunks, where the cut points are defined by some internal features of the files. Unlike fixed-length chunks, variable-length chunks are more resistant to byte shifting. Thus, it increases the probability of finding duplicate chunks within a file and between files. However, CDC algorithms require additional computation to find the cut points which might be computationally expensive for some applications. In our previous work (Widodo et al., 2016), the hash-based CDC algorithm used in the system took more process time than other processes in the deduplication system. This paper proposes a high throughput hash-less chunking method called Rapid Asymmetric Maximum (RAM). Instead of using hashes, RAM uses bytes value to declare the cut points. The algorithm utilizes a fix-sized window and a variable-sized window to find a maximum-valued byte which is the cut point. The maximum-valued byte is included in the chunk and located at the boundary of the chunk. This configuration allows RAM to do fewer comparisons while retaining the CDC property. We compared RAM with existing hash-based and hash-less deduplication systems. The experimental results show that our proposed algorithm has higher throughput and bytes saved per second compared to other chunking algorithms.     

Dynamic pricing with stochastic reference effects based on a finite memory window

Inspired by the latest empirical studies, we propose a new updating model for reference prices by assuming that consumers’ memories are limited and their recall of previous prices obeys a first-order Markov stochastic process. We investigate a dynamic pricing model with stochastic reference effects and finite memory. Consistent with the exponential smoothing model, we indicate that reference effects lead to monotonic convergence of the optimal price path to an expected steady-state price. The steady-state range tends to widen as consumers become loss-averse. The results of our numerical experiments differ from findings of certain models under the assumption of stochastic recall memory of consumers. The optimal price path fluctuates consistently around the steady state instead of remaining constant. The effect of the first price on the memory window and long-term profits decreases as the length of memory window increases.     

Limitation of cracking in AAC masonry under the window zone

The article describes the results of tests on the impact of reinforcement on the appearance of cracks and on the manner of damage to masonry under the window zone. Masonry made of Autoclaved Aerated Concrete units with thin layer mortar was tested. Eight unreinforced test specimens (two series) and four series of test specimens (12 specimens) with reinforcement in the bed joints were subject to testing. Two types of reinforcement were used in the tests. It is demonstrated that the reinforcement has a significant impact on the level of cracking stress and propagation of cracks. It was found that when a pillar is correctly designed, cracks should not occur in the masonry under the window zone.     

Two-step sintering behavior of titanium-doped Y2O3 ceramics with monodispersed sub-micrometer powder

Two-step sintering of titanium-doped Y₂O₃ was carried out using monodispersed sub-micrometer powder. The effect of titanium dopant concentration on the sinterability and kinetic window of constant grain-size sintering were examined. The titanium doping improves the sinterability of the Y₂O₃ powder, which broadens the sintering kinetic window and lowers sintering temperature. The Vickers hardness was also enhanced as the doping concentration of titanium was increased, assuming the same grain size.