SMART-Reactors: Tailoring Gas Holdup Distribution by Additively Manufactured Lattice Structures

In chemical process engineering, fast gas-liquid reactions often suffer from an inefficient distribution of gas and therefore mixing and mass transfer performance. This study deals with the possibility of influencing the local gas holdup and bubble size distribution in a gas-liquid process using additively manufactured lattice structures (AMLS). The used measuring technique to study bubble size, velocity, and the local gas holdup is a photo-optical needle probe. By using AMLS, a significant radial homogenization of the local gas holdup and the mean bubble size is achieved. Furthermore, it can be demonstrated that the bubble size can be tailored by the geometry of the inserted structure. It is illustrated that the mean bubble velocities are lowered within the lattice resulting in a higher residence time of the dispersed phase with an impact on the mass transfer performance within the AMLS.     

用弦角测量控制法确定型材成形的模拟实验与分析

船用型材冷弯成形常采用端点测量控制法,但采用该方法时,冷弯设备的检测机构庞大、操作不便、造价高、难于制造和安装。为此,提出一种弦角测量控制法代替传统的端点测量控制法实现型材的冷弯成形。为了验证该方法的可行性,采用铜线模拟型材的中性层曲线进行压弯实验,同时对压弯的支点距离、进料步长等进行分析和论证。结果表明,采用该方法获得的铜线形状与型材样条曲线基本吻合。研究结果可为型材冷弯成形提供理论依据。     

全扁平化网络中的分布式用户数据管理

在介绍传统DHT算法自习基础上,总结与探讨了适合未来移动网络的分布式数据管理方案,并针对传统Chord算法提出了几种增强型方案。     

基于Chord的移动对等网络资源路由算法

针对移动P2P云环境下节点由于移动太快导致路由算法失效的问题,提出一种基于Chord资源路由算法。该算法修改基本路由结构,并设置实时机制和检查机制,实时机制在每次查找过程中实时修改路由信息,检查机制是检查路径节点是否为有效节点,并修改路径节点路由信息,提供给下次查询使用。实验结果表明,该算法有效提高查询成功率,同时减少查询延时。     

基于IAPWS-IF97的第3区水和蒸汽密度的迭代计算

目前我国稠油油田开始使用额定工作压力接近临界状态的注汽锅炉。在开发注汽锅炉时,要涉及到接近临界状态的水和蒸汽性质的计算。临界状态在IAPWS-IF97工业标准中被划分为第3区,此区的水和蒸汽性质的计算公式都与水和蒸汽的对比密度有关,而标准中并没有具体给出密度的求解方法。基于IAPWS-IF97公式推导出密度的求根方程,再采用弦截法迭代求出。这种方法运算速度快,收敛性好,算出的密度值与性质表给出值十分接近。     

基于传动系统动力学的NURBS曲线插补算法

对机床传动系统、伺服驱动系统和数控插补模块进行动力学建模和求解.提出一种新的NURBS插补算法,按照进给率自适应轨迹规划算法进行当前插补周期的速度设定,并且根据曲线当前位置的曲率特性,进行基于曲率的最大速度限定,通过求解动力学模型,获得按照这一速度进行插补时系统需要的最大驱动力,若该驱动力超过系统能够提供的最大驱动力,则再次按照用户设定的加速度进行减速,获得的速度作为指令速度,按照一阶泰勒展开近似进行插补点的计算.该算法不仅在NURBS曲率较大的区域自动降低进给速度,保证要求的弦误差,而且使输出的插补速度指令区域平滑,保证不会出现插补输出的位置值系统无法进行位置控制造成更大的加工误差.     

三点透视作图新法──旋转法

根据射影几何的透视变换原理，解决了画三点透视时经常遇到的灭点在板外的实际作图问题，所提出的方法是研究透视作图的快捷方法。     

A multi-level optimization methodology for determining the dextrous workspaces of planar parallel manipulators

A numerical multi-level optimization methodology is proposed for determining dextrous workspaces of 3-degree-of-freedom (3-dof) planar parallel manipulators, in which it is required that at any point within the workspace, the manipulator is able to assume any orientation in a specified range. The method starts by finding a single initial point on the boundary of the dextrous workspace. This first stage requires the successive solution of three separate optimization sub-problems, where the evaluation of the objective function for the second problem and the constraint functions in the third problem are determined by the solution of appropriate optimization problems at a lower level. Once the boundary point is identified, further successive points along the dextrous workspace boundary are traced by the application of the so-called chord method. In the latter procedure, the determination of each successive boundary point is also obtained via a constrained optimization problem, where the constraint functions are again evaluated via the solution of an optimization problem at a lower level. The proposed method is illustrated by its successful application to three different manipulator design geometries, and for various ranges of dexterity. An abbreviated version of this paper was presented at the 5th ASMO UK/ISSMO conference on Engineering Design Optimization, Stratford upon Avon, UK, July 12–13, 2004.     

Y型管节点应力集中系数有限元分析

用有限元计算了位于渤海湾的BZ-28单点停泊系统导管架Y型管节点在轴向力，平面内弯矩以及平面外弯矩作用下的热点应力集中系数以及支管和弦管应力集中系数的分布，并将结果与常用的参数公式进行比较。     

A parametric interpolator with confined chord errors, acceleration and deceleration for NC machining

Parametric interpolation has many advantages over linear interpolation in machining curves. Real time parametric interpolation research so far has addressed achieving a uniform feed rate, confined chord errors and jerk limited trajectory planning. However, simultaneous consideration of confined chord errors that respect the acceleration and deceleration capabilities of the machine has not been attempted. In this paper, the offline detection of feed rate sensitive corners is proposed. The velocity profile in these zones is planned so that chord errors are satisfied while simultaneously accommodating the machine's acceleration and deceleration limits. Outside the zone of the feed rate sensitive corners, the feed rate is planned using the Taylor approximation. Simulation results indicate that the offline detection of feed rate sensitive corners improves parametric interpolation. For real time interpolation, the parametric curve information can be augmented with the detected feed rate sensitive corners that are stored in 2×2 matrices.