叶序排布展开结构微混合器混合特性模拟分析

为了提高液体混合的效率,根据生物科学中的叶序理论,设计柱状叶序排布展开结构的微混合器.利用计算机对混合效果进行仿真,获得了叶序系数、微圆柱直径对微混合器混合效果的影响规律,微圆柱的叶序排布、矩阵排布、错位排布的混合效果进行对比.结果表明:微圆柱叶序排布的混合器混合效率最高,混合液体在混合通道中沿着顺时针和逆时针叶列螺旋沟槽流动,液体能更好的交互扩散流动,有利于液体混合.     

Design,manufacture and geometric verification of rapid prototyped microfluidic encapsulations by computed tomography

This paper presents the dimensional verification of encapsulations used to package microfluidic devices manufactured using a 3D printer of photopolymerisable resin. This characterisation has been performed by computed tomography (CT) by comparing newly manufactured encapsulations and samples that have been subjected to test conditions. Thus, it has been possible to draw conclusions both on the deviations of the nominal geometry of the encapsulations and on how this might affect their performance. This paper presents a scheme of dimensional verification from the point clouds obtained by CT. Finally, a combined threshold and scale factor correction technique of the tomography images is shown. This method is based on the simultaneous measurement of objective and master parts with known geometry. The results reveal the improvements achievable in the accuracy, given a particular machine configuration. The conclusions facilitate the improvement of the geometric design of these devices regarding their behaviour under test conditions.     

A simple neuron servo

A simple servo controller built from components having neuronlike features is described. This VLSI servo controller uses pulses for control and is orders of magnitude smaller than a conventional system. The basic circuit elements are described. A key element is a component and neuronlike capability that takes voltages as inputs and generates a pulse train as the output. It is shown how the circuits are combined to a proportional and derivative controller. The advantages of using a pulsed output representation to improve slow-speed operation of a friction-limited system is demonstrated. The utility of exploiting parallelism, aggregation, and redundancy to improve system-level performance given imprecise low-level components is discussed. Experimental results illustrate the properties of the system compared with conventional controllers.     

A simple row-replacement method

Updating a video screen involves row replacement, i.e, the task of updating an existing screen row to produce the desired row. In many environments, screen operations require transmitting characters to the terminal by a process that is painfully slow compared to computing speeds. Thus, it is worth while to compute a minimal set of row updating commands, as long as the time to do so does not outweigh the savings in character transmission time. This paper presents a simple and practical algorithm for optimal row replacement and describes experience with its use in a screen editor.     

A simple reflective interpreter

Procedurally reflective programming languages enable user programs to semantically extend the language itself, by permitting them to run at the level of the language implementation with access to their context. The reflective tower, first introduced by Brian Smith, is the principal architecture for such languages. It is informally described as an infinitely ascending tower of metacircular interpreters, connected by a mechanism that allows programs at one level to run at the next higher level. Various accounts of the reflective tower have been published, including a metacircular definition, operational definitions, and denotational definitions. We present an operational account of the main aspects of the reflective tower, which we claim is simpler than previous accounts. Our approach is to implement a finite tower where each level literally runs the level directly below it. A complete Scheme implementation is included.An earlier version of this paper appeared inProceedings of the International Workshop on New Models for Software Architecture '92: Reflection and Meta-level Architecture, November 1992. This material is based on work supported by the National Science Foundation under Grants NSF CCR 89-01919 and NSF CCR 90-00597.     

A simple interactive graphics facility

This paper describes the incorporation of a graphics facility into an existing interactive system. Emphasis is placed on the importance of an inexpensive system with a simple user interface. Details of some implementation considerations are given.     

A simple bilinear optimization problem

Multilinear optimization problems arise in many contexts, yet already the bilinear case, even for variables restricted to parallelotopes, is intractable in general. As an example of a manageable case, which may also be used to bound other cases, the elementary problem of maximizing the inner product of two vectors, each constrained to a sphere, is solved here.     

A simple contour matching algorithm

Two similarity measures between strings are proposed. This correspondence also describes an experiment performed to illustrate the inadequacy of a commonly used measure.     

A simple quadrilateral shell element

The paper describes a new four-noded quadrilateral shell element, called QUAD4, which is based on isoparametric principles with modifications which relax excessive constraints. The modifications include reduced order integration for shear terms, enforcement of curvature compatibility, and the augmentation of transverse shear flexibility to account for a deficiency in the bending strain energy. Practical features are discussed, including conversion to a nonplanar shape, coupling between bending and stretching, mass properties, and geometric stiffness. Experimental results are described which illustrate the accuracy and economy claimed for the element.     

A simple linear-time algorithm for in situ merging

It is generally believed that the time-cost of solving any size n problem using two-way divide-and-conquer is minimized by balancing—that is, by dividing the problem into subproblems of size $\text{?}\text{n}\text{2}\text{?}$ and $\text{?}\text{n}\text{2}\text{?}$. A counter-example is presented: balanced division, applied to finding the greatest and least elements of a size n set, will in the worst case force 11% more comparisons to be made than an optimal division such as into subsets of sizes 2 and n?2. A necessary condition and a slightly stronger sufficient condition are given for balancing to be cost-optimal. Even if balancing is cost-optimal, it may not be the only cost-optimal division strategy; a necessary and sufficient condition is given for a division strategy to be ‘balanced enough’ to be cost-optimal. As an application, a new iterative merge-sorting algorithm is presented which requires no more comparisons than the balanced one of Erkio and Peltola (1977) but merges subarrays consisting of consecutive elements of the whole array.     

简单新闻发布系统的设计

在ASP.NET教学中,设计了一个新闻发布系统的案例,在设计与教学中,有一些心得,写出来与大家共享,如有不妥之处,望与我联系,我们共同改进.本系统分发布新闻棋模块、新闻管理模块、新闻显示模块来处理的.为了在描述方便,数据库使用access2003,设计平台用vs2005.     

A simple model of evolving ecosystems

We investigate the structural properties of an ecosystem model, and show that the model and the field data share similar characteristics. In particular, our model suggests that the universal scaling of the “spanning tree,” which has been discussed using the field data on fewer than 100 species only, can be valid on a larger scale. This work was presented in part at the 11th International Symposium on Artificial Life and Robotics, Oita, Japan, January 23–25, 2006     

A simple mechanism for curvature detection

This paper presents a simple and biologically plausible algorithm for detecting and discriminating between line features of various curvatures. The algorithm involves filtering the input image with a set of directional filters, and computing the filter response energy (local energy). The curvature information is obtained from analysing the local energy information. The algorithm is insensitive to noise (up to 64 dB) and the orientation of the features present in the input image.     

一种基于DDS的简易便携式扫频仪设计

本设计是以STC89C52单片机作为主控芯片,控制一片高速DDS数字频率合成器AD9850,产生两路相正交的扫频信号并实现闭环稳幅,通过D/A和A/D转换器等接口电路,实现扫频信号频率的步进调整、数字显示等.本设计克服了传统模拟扫频仪的缺点,针对目前中低频段的扫频仪比较少的现状,具有很大的应用前景.     

A simple efficient hidden line algorithm

A simple efficient hidden line algorithm for finite element models is described. The algorithm is general purpose, requires minimal computer storage, and can easily be added to existing plot programs. The routine does not require angle determination, trigonometric functions, or elaborate bookkeeping schemes. Detailed flowcharts and a listing of the computer code are presented.