Single-crystal diamond micro-cupped resonators made by laser ablation

This paper presents a novel three-dimensional fabrication process of micro-scale shell resonator made of single-crystal diamond (SCD) called micro-cupped resonator (MCR). The key feature of the process is the application of laser ablation, which can contribute to the shaping process of SCD with higher accuracy, better structural symmetry, greater speed, and lower breakage rate. UV laser high precision processing machine has been employed for the ablation of SCD in the present investigation. This paper describes the principle of laser ablation of SCD and analyses the effects of beam parameters on ablation quality. Then MCR with better structural symmetry and less structural imperfection has been successfully fabricated based on optimum parameters by laser ablation. The MCR is promising for emerging applications such as micro rate-integrating gyroscope.     

基于动捕数据驱动的三维民族舞蹈展示方法

三维模型动画在数字化设计和应用中具有重要意义,受到越来越多研究者关注;但如何通过三维数字化原真再现民族舞蹈表演是极具挑战的问题.本论文通过动捕技术采集舞蹈动作实现舞蹈数字化展示.具体方法是:首先利用动捕设备捕获人体动作数据,然后在Maya中进行人物建模、骨骼绑定、蒙皮和权重调节,再通过MotionBuilder将3D模型与动捕数据结合,最终完成了现实舞蹈动作的虚拟人展演.论文构建了一个面向民族舞蹈展演的虚拟场景,并以13个民族的舞蹈为数字化内容,推广动捕驱动的舞蹈展演方法的应用.     

Multimedia cloud transmission and storage system based on internet of things

For the issues of large space and storage security of multimedia files, we analyzed the impact of access control and cloud storage on multimedia file, and proposed a mixed security cloud storage framework based on Internet of Things. This paper introduced the concept of multimedia protection into the method based on role access control. Moreover, we also adopted a scheme based on the combination of multimedia data state and role access control. At the same time, all input and output devices were connected to this system. Internet of Things is used to judge whether circuits are connected and whether the devices are normally operated, so as to improve the access efficiency. On this basis, we also described in detail the complete process of registration, role assignment, multimedia file owner’s request for data encryption, and user login and access to multimedia file. According to the result, this scheme can be used to resist the known attacks. It guarantees security of multimedia files.     

An effective suggestion method for keyword search of databases

This paper solves the problem of providing high-quality suggestions for user keyword queries over databases. With the assumption that the returned suggestions are independent, existing query suggestion methods over databases score candidate suggestions individually and return the top-k best of them. However, the top-k suggestions have high redundancy with respect to the topics. To provide informative suggestions, the returned k suggestions are expected to be diverse, i.e., maximizing the relevance to the user query and the diversity with respect to topics that the user might be interested in simultaneously. In this paper, an objective function considering both factors is defined for evaluating a suggestion set. We show that maximizing the objective function is a submodular function maximization problem subject to n matroid constraints, which is an NP-hard problem. An greedy approximate algorithm with an approximation ratio O(\(\frac {1}{1+n}\)) is also proposed. Experimental results show that our suggestion outperforms other methods on providing relevant and diverse suggestions.     

Competition in wearable device market: the effect of network externality and product compatibility

The rapid growth in consumer adoption of wearable devices has garnered the attention of both practitioners and academia. Competition in the wearable device market is both substantial and complicated. In this study, we investigate the impact of network externality on wearable device competition in a two-dimensional product differentiation model. We consider a market that has a broad array of products (horizontal differentiation) and various quality levels (vertical differentiation). We study two types of network externalities according to the product compatibility in two types of market structures. Our model indicates that firm profits are decreased by network externalities in horizontal dominance. Network externality also increases (decreases) the higher-quality (lower-quality) firm’s profit in vertical dominance. Moreover, firms should ensure that their products are incompatible with those of rivals when network externality is large, and they should release compatible products when network externality is small in horizontal dominance. Firms should always ensure that their products are compatible with those of competitors in vertical dominance.     

A novel Minkowski-distance-based consensus clustering algorithm

Consensus clustering is the problem of coordinating clustering information about the same data set coming from different runs of the same algorithm. Consensus clustering is becoming a state-of-the-art approach in an increasing number of applications. However, determining the optimal cluster number is still an open problem. In this paper, we propose a novel consensus clustering algorithm that is based on the Minkowski distance. Fusing with the Newman greedy algorithm in complex networks, the proposed clustering algorithm can automatically set the number of clusters. It is less sensitive to noise and can integrate solutions from multiple samples of data or attributes for processing data in the processing industry. A numerical simulation is also given to demonstrate the effectiveness of the proposed algorithm. Finally, this consensus clustering algorithm is applied to a froth flotation process.     

Fabrication of circular microfluidic channels through grayscale dual-projection lithography

Circular microfluidic channels are in great demand since they are more realistic in mimicking physiological flow systems, generating axis-symmetrical flow, and achieving uniform shear stress. A typical microchannel with rectangular cross section can induce non-physiological gradients of shear rate, pressure, and velocity. This paper presents a novel method of fabricating microfluidic channels with circular and elliptical cross sections through grayscale dual-projection lithography. Our method utilizes two projecting systems to expose grayscale image face-to-face and simultaneously polymerize the photocurable material. The cross-sectional profiles of the fabricated microchannels are consistent with mathematical predictions and, therefore, demonstrate the capability of controlling the channel shapes precisely. Customized circular microchannels can be generated with complex features such as junctions, bifurcations, hierarchies, and gradually changed diameters. This method is capable of fabricating circular channels with a wide range of diameters (39 μm–2 mm) as well as elliptical channels with a major-to-minor axis ratio up to 600%. Microfluidic devices with circular cross sections suitable for particle analysis were made as a demonstrative application in nanoparticle binding and distribution within a mimetic blood vessel. A ready-to-use microfluidic device with customized circular channels can be fabricated within 1 h without the need of clean room or expensive photolithography devices.     

基于WiFi通讯的磁浮车间隙传感器测试系统设计

针对磁浮车间隙传感器工作环境恶劣需要频繁地测试与维护的问题,应用无线通讯技术、虚拟仪器技术、数字信号处理技术,设计了一种基于WiFi通讯的磁浮车间隙传感器测试系统,该系统在原有磁浮车间隙传感器的基础上增加WiFi模块使传感器具有无线通讯功能,采用具有WiFi通讯功能的便携式PC机作为系统的监控终端,利用图形化编程语言LabVIEW编写监控终端的人机交互界面。测试结果表明：该系统工作稳定可靠、操作简便,实现了对间隙传感器特性的无线测试、存储、分析和非线性校正,非线性校正后的间隙传感器具有良好的线性特性,其输入输出特性达到了磁浮车悬浮控制系统的要求,可用于悬浮控制系统的闭环控制。     

统计算法选择对统计模型检测效率的影响分析

近年来,统计模型检测技术已经得到了广泛的应用,不同的统计算法对统计模型检测的性能有所影响。主要对比不同统计算法对统计模型检测的时间开销影响,从而分析算法的适用环境。选择的统计算法包括切诺夫算法、序贯算法、智能概率估计算法、智能假设检验算法及蒙特卡罗算法。采用无线局域网协议验证和哲学家就餐问题的状态可达性验证为实例进行分析,使用PLASMA模型检测工具进行验证。实验结果表明,不同的统计算法在不同的环境中对模型检测的效率有不同的影响。序贯算法适用于状态可达性性质的验证,时间性能最优;智能假设检验算法与蒙特卡罗算法适合验证复杂模型。这一结论有助于在模型检测时对统计算法的选择,从而提高模型检测的效率。