Tunable structures of compound droplets formed by collision of immiscible microdroplets

We study the dynamics of a small water droplet colliding with an immiscible large sessile oil droplet in the air. Such a three-phase system forms compound microdroplets with tunable structures, depending on whether the small droplet can penetrate into the large one. A structure of penetrative-engulfing is distinguished from structures which are determined by balancing of the three interfacial tensions among the three phases, i.e., partial-engulfing and complete-engulfing. We develop a three-phase volume-of-fluid method to investigate the collision dynamics numerically, considering the evolution of the triple-line among the three interfaces. Regime maps of the structures for different spreading parameters and heights of the oil droplet are obtained regarding the impact velocity and the viscosity ratio of oil and water. We find that the oil droplet is impenetrable when the viscosity ratio is higher than a critical value. For lower ratio, the structure varies non-monotonically with the impact velocity to cause two transitions. We propose a simple model for the lower transition by incorporating droplet deformation, viscous resistance, and spreading condition. The upper transition boundary is influenced by the spreading of the oil droplet, resulting in an increase in the required penetration length to prevent penetrative-engulfing. Understandings from this work may provide valuable guidelines for generating compound microdroplets with desired structures.     

Droplet-based biochemical assay by magnetic wire manipulation between multiple droplets

Reaction performance of a droplet-based biochemical assay technique that uses magnetic wires as sample carriers is evaluated. Wires 2.0 mm in length, 0.05 mm in width, and 0.02 mm in thickness are fabricated by chemical etching, introduced into a droplet immersed in oil, and manipulated by the magnetic force of a moving magnet. Alkaline-phosphatase as an enzyme is immobilized on the wire surfaces by applying Au and self-assembled monolayer coatings, and the method’s on-chip reaction performance is evaluated. The enzymatic reaction is found to increase linearly as the number of wires and the reaction time increase. Relatively high performance reproducibility for enzymatic reactions is obtained; on average, the reaction absorbance, standard deviation, and coefficient of variance are found to be respectively 1.14, 0.103, and 9.1 %. The conductivity change in a fused droplet is used to evaluate the absolute volume of liquid transferred with the extracted wires and a value of 0.33 μl is obtained.     

基于事件触发机制的双编队车辆换道决策模型

针对由联网自动化车辆(connected and automated vehicle,CAV)组成的双编队车辆换道问题进行了研究,提出了一种基于事件触发的分布式换道决策模型.该模型针对双编队系统设计了一种编队内和编队间的一致性控制协议;同时,为了减少CAV车辆控制器的频繁更新,设计了一种基于组合测量方式的事件触发器,并给出Lyapunov函数证明了算法的稳定性且不存在Zeno行为.仿真结果表明,所设计的控制协议能够使双编队系统收敛一致,有效降低CAV控制器的更新频率,减少系统能耗.通过模型对比,在证明所提决策模型有效性的同时,系统能够更快地收敛.     

Flow of two immiscible liquids with low viscosity in Y shaped microfluidic systems: effect of geometry

This article investigates the formation of albumin droplets in fatty esters by means of a flow focussing geometry where the continuous oil phase is introduced in the two lateral branches of a Y junction. The effect of the geometry is investigated in order to clarify the scales controlling the droplet generation with this type of fluid couple. The transition from regular droplet flow to stratified flow is identified from the experiments. It is found that the droplet size varies linearly with the flow rate ratio between the disperse and continuous phases. This is similar to what is found in T junctions microfluidic systems for low capillary numbers.     

Interactions between two neural populations: A mechanism of chaos and oscillation in neural mass model

Neural mass model developed by Lopes da Silva et al. is able to describe limit cycle behavior in Electroencephalography (EEG) of alpha rhythm and exhibit complex dynamics between cortical areas. In this work, we extend Grimbert and Faugeras's work to study the dynamical behavior caused by interaction of cortical areas. The model is developed with the coupling of two neural populations. We show that various attractors, including equilibrium points, periodic solutions and chaotic strange attractors, could coexist in different ways with different value of the connectivity parameters. The main findings are that: (1) The stable equilibrium points only appear with a small value of the parameter. (2) While the alpha activities always exist for both two populations with proper initial conditions. Interestingly, the coexistence of the multiple alpha-to-epileptic activities implies the multiple coupling ways for these activities in phase. Two neuronal populations with epileptic activities could interact with multiple rhythms depending on their connectivity. (3) For particular interest, chaotic behaviors are identified in four regions divided by the connectivity parameter with the positive maximal Lyapunov exponent. The four types of chaotic attractors have their own structures, but all of them are related to the epileptic activities.     

两轮摩托车变挡机构动力学分析

用Adams建立某两轮摩托车的虚拟样机,对其变挡机构进行动力学仿真计算,找出影响变挡脚踏力的关键因素,提出优化设计思路,解决该车在使用过程中脚踏变挡不顺畅且费力的问题,提高该车型的综合性能.     

Comparison between two theories of plasticity

Among numerous large strain elasto-plasticity theories, Green-Naghdi's theory and E. H. Lee's theory are distinguished and distinctive. In Green-Naghdi's theory, the Green-Lagrange strain tensor is decomposed into the elastic and the plastic parts. On the other hand, E. H. Lee started with a decomposition of the deformation gradient into a product of two parts: elastic and plastic. In the case of simple tension, the essential differences arc found between these two theories. In E. H. Lee's theory, the unloading curves are parallel on the plots of Cauchy stress vs natural strain. However, this parallel relation does not exist on the plots of Piola-Kirchhoff stress vs Green-Lagrange strain. In Green-Naghdi's theory, the results are reversed. The unloading curves are not parallel on the plots of Cauchy stress vs natural strain, but parallel on the plots of Piola-Kirchhoff stress vs Green-Lagrange strain. The significance of this finding is further discussed.     

Asymptotic equivalence between two difference systems

In this paper, we study the asymptotic equivalence between the linear system Δx(n) = A(n)x(n) and its perturbation Δy(n) = A(n)y(n)+g(n, y(n)) by using the comparison principle and supplementary projections. Furthermore, we establish some asymptotic properties for the nonlinear system Δx(n) = f(n, x(n)).     

Shortest path between two simple polygons

Consider a collection of mutually disjoint simple polygons in the plane containing a total of n edges. Two of them are specified as a source polygon S and a target polygon T. We present an efficient algorithm for finding a shortest path between S and T avoiding the other polygons. We show that it runs in O(n²) time, using a linear-time algorithm for computing the visibility polygon of a point. This problem is related to a wire routing design of a certain type of LSI for which terminals are of polygonal shape and larger than a wire segment.     

Minimum distance between two sphere-swept surfaces

We present an efficient and robust approach for computing the minimum distance between two sphere-swept surfaces. As examples of sphere-swept surfaces, we consider canal surfaces and bivariate sphere-swept surfaces. For computing the minimum distance between two parametric surfaces, a simple technique is to find the two closest points from the given surfaces using the normal vector information. We suggest a novel approach that efficiently computes the minimum distance between two sphere-swept surfaces by treating each surface as a family of spheres. Rather than computing the complicated normal vectors for given surfaces, our method solves the problem by computing the minimum distance between two moving spheres. We prove that the minimum distance between two sphere-swept surfaces is identical to that between two moving spheres. Experimental results of minimum distance computation are given. We also reproduce the result of Kim [Kim K-J. Minimum distance between a canal surface and a simple surface. Computer-Aided Design 2003;35:871-9] based on the suggested approach.     

Identifying syntactic differences between two programs

Programmers frequently face the need to identify the differences between two programs, usually two different versions of a program. Text-based tools such as the UNIXr? utility diff often produce unsatisfactory comparisons because they cannot accurately pinpoint the differences and because they sometimes produce irrelevant differences. Since programs have a rigid syntactic structure as described by the grammar of the programming language in which they are written, we develop a comparison algorithm that exploits knowledge of the grammar. The algorithm, which is based on a dynamic programming scheme, can point out the differences between two programs more accurately than previous text comparison tools. Finally, the two programs are pretty-printed ‘synchronously’ with the differences highlighted so that the differences are easily identified.     

Media multitasking between two conversational tasks

Communication multitasking was examined in three conditions: IM conversation with one partner, two IM conversations at the same time, and IM and phone conversation at the same time. Participants in the multitasking conditions reported higher task demand and a small loss in task performance was evident. Single-task partners assigned to a task the required discussion and deliberation preferred to interact with the multitasking participant via phone, rather than IM. But interactions via phone with one partner led to poorer assessment by a second partner who was shortchanged during the interaction. Multitasking participants who were focused on helping both partners seemed blind to these perceived differences by their single-task partners. The results suggest a strategic model of multitasking, with IM being the preferred choice for tasks that require fewer, shorter exchanges and voice being the preferred choice for tasks that required more discussion and deliberation.     

Isomorphism between two BL-general fuzzy automata

In this note first we develop the notion of general fuzzy automata (GFA) to a new one which is called “BL-general fuzzy automata” and for simplicity, we write BL-GFA, instead of BL-general fuzzy automata. Then we focus on derivation, active state set, membership assignment, output mappings, and concept of belonging to an output label according to the entrance input strings \( X \, (X \in \Upsigma^{ * } ) \) for BL-general fuzzy automata. Therefore, we define the concepts of run map and behavior of BL-GFA. After that we present the morphism with threshold \( \tfrac{{\tau_{1} }}{{\tau_{2} }} \) between two BL-general fuzzy automata. Moreover we give some examples, to clarify these notions. Finally, we prove some theorems. In particular, we show that the isomorphic BL-general fuzzy automata have the same behavior.     

基于双向融合机制的建筑目标检测方法

模拟人类视觉中有意识主动寻找与无意识被动受吸引相交互的视觉过程,提出了一种基于双向融合机制的建筑目标检测方法.该方法综合了基于自底向上数据驱动的视觉显著性模式和自顶向下基于环境感知的目标搜索模式检测图像中的建筑目标区域.利用拍摄的自然图像进行实验表明:该方法能较好地检测出图像中的建筑目标,具有处理速度快、准确性高的特点,能够满足处理复杂场景图像的实时性要求.