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The ability to separate and analyze chemical species with high resolution, sensitivity, and throughput is central to the development of microfluidics systems. Deterministic lateral displacement (DLD) is a continuous separation method based on the transport of species through an array of obstacles. In the case of force-driven DLD (f-DLD), size-based separation can be modelled effectively using a simple particle-obstacle collision model. We use a macroscopic model to study f-DLD and demonstrate, via a simple scaling, that the method is indeed predominantly a size-based phenomenon at low Reynolds numbers. More importantly, we demonstrate that inertia effects provide the additional capability to separate same size particles but of different densities and could enhance separation at high throughput conditions. We also show that a direct conversion of macroscopic results to microfluidic settings is possible with a simple scaling based on the size of the obstacles that results in a universal curve.  相似文献   

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Inertial microfluidics is an emerging class of technologies developed to separate circulating tumor cells (CTCs). However, defining design parameters and flow conditions for optimal operation remains nondeterministic due to incomplete understanding of the mechanics, which has led to challenges in designing efficient systems. Here, we perform a parametric study of the inertial focusing effects observed in low aspect ratio curvilinear microchannels and utilize the results to demonstrate the isolation of CTCs with high purity. First, we systematically vary parameters including the channel height, width, and radius of curvature over a wide range of flow velocities to analyze its effect on size dependent differential focusing and migration behaviors of binary (10 μm and 20 μm) particles. Second, we use these results to identify optimal flow regimes to achieve maximum separation in various channel configurations and establish design guidelines to readily provide information for developing spiral channels tailored to potentially arbitrary flow conditions that yield a desired equilibrium position for optimal size based CTC separation. Finally, we describe a fully integrated, sheath-less cascaded spiral microfluidic device to continuously isolate CTCs. Human breast cancer epithelial cells were successfully extracted from leukocytes, achieving 86.76% recovery, 97.91% depletion rate, and sustaining high viability upon collection to demonstrate the versatility of the device. Importantly, this device was designed without the cumbersome trail-and-error optimization process that has hindered the development of designing such inertial microfluidic systems.  相似文献   

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This study proposes a spectral domain algorithm to remove the deterministic non-periodic trend from a time series using a class of fast, sharp and diffusive filters. These filters are principally the iterative moving least squares methods weighted using Gaussian windows. The responses of the filters expressed in analytic forms are proven to be diffusive. If it is a polynomial of finite degree, the embedded trend can be decoupled by the filters with specific order and iteration steps. The filters’ order, transition zone, error tolerance, iteration number and smoothing factor are subject to two algebraic equations to form a specific class. The operation counts of all filters are slightly larger than twice that applying a Fast Fourier Transform (FFT). It is numerically shown for a given transition zone and tolerance, there is a filter generating the shortest error penetration distance among all the filters. If either the trend or a spectral band is the main concern, there is an optimal strategy to shrink the error penetration distance. The numerical results show the filter has better performance than several existing methods. In addition, four examples successfully show direct applications of the filter’s response.  相似文献   

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In this paper, a novel semi-active variable admittance (VA) concept is proposed, and a seat suspension prototype with a magnetorheological fluid damper based rotary VA device is designed, manufactured, and experimentally validated. The conventional inerter with a single flywheel has a constant inertance, which can effectively improve the suspension performance by being integrated into a mechanical network with springs and dampers. The proposed rotary VA device comprises a gear reducer, two flywheels and a variable damping (VD) device which is used to connect the two flywheels. With carefully designing, the rotary VA device is compacted and is similar with a VD device in size. The rotary VA device is installed in the centre of a seat suspension's scissors structure to form a VA seat suspension. According to the test results, the equivalent inertance of the seat suspension can vary from 11.3 Kg–76.6 Kg with a 3 Hz frequency and 5 mm amplitude sinusoidal movement by changing the current from 0 A–1 A. By analysing the system characteristics, a hybrid controller with two acceleration feedbacks is proposed. Thereafter, the seat suspension and controller are validated in experiments by comparing the performance with a conventional passive seat suspension. The random vibration test shows the excellent performance of the proposed seat suspension; the frequency weighted root mean square acceleration of the seat is reduced by 43.6%, which indicates a great improvement of the ride comfort. The VA device shows great prospect in the suspension application.  相似文献   

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主要介绍了新型溜槽角度测量装置的研制与应用,设计了专用防护装置,并通过PLC编程实现了高炉布料的工艺要求.  相似文献   

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文章通过电镜扫描对广西地区桫椤科植物的7个种的孢子形态和周壁纹饰进行观察。对每个种的孢子形态特征及表面纹饰进行了研究。桫椤科蕨类植物孢子为辐射对称,极面观为三角形,三角形三边直或者向内凹陷,赤道面观为扇形,具有三裂缝,裂缝长度约为孢子长度的3/4或不明显。孢子周壁表面光滑或形成片状纹饰和翅状纹饰。根据桫椤科孢子形态和周壁纹饰,对桫椤科植物的科下分类进行了探讨。  相似文献   

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岑忠彩  刘义强 《大众科技》2011,(12):132-133,108
针对企业常用的笼型异步电机工况,通过分析软起动器的工作原理及常用的几种起动方式,阐述了软起动器的使用、选型时应注意事项。  相似文献   

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细菌觅食算法在求解水库优化调度问题时,以固定的步长进行趋向操作,同时以固定概率对细菌个体进行随机驱散操作,虽然可以一定程度上增加种群多样性,但是在进化后期容易使优秀的个体流失,影响算法的寻优质量。针对该问题,文章提出步长自适应调整和驱散概率自适应调整两项改进策略,根据算法进化程度和细菌个体的能量值动态调整趋向操作的步长和驱散操作的概率,使算法进化过程中尽量保证种群多样性的基础上,提高细菌个体的觅食能力,进一步促进算法达到局部搜索和全局优化之间的平衡。将改进的细菌觅食算法应用于乌江梯级水库群的联合优化调度问题,模拟结果表明:改进细菌觅食算法具有较强的全局寻优能力,适合求解梯级水库联合优化调度问题。  相似文献   

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容斥原理是组合计数的一个重要工具,本文对容斥原理的表现形式作了一些归纳总结,对其在恒等式方面的应用作了简短阐述。  相似文献   

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This paper proposes a robust active-passive decomposition (APD) synchronization scheme. Compared with the original APD scheme, the robust APD scheme can effectively deal with the uncertainty in the master. Further, this scheme can also be applied to secure communication, where the hidden message can be recovered by the concept of equivalent control. Simulation results of Lorenz system verify the effectiveness of the proposed scheme.  相似文献   

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Given the growing importance of online social media platforms (OSM) in brand management, the authors attempt to extend the relationship between e-brand equity and repurchase intention with two mediator variables, namely visual appeal and e-preference in which willingness to pay a price premium (WPPP) serves as a moderator. Drawing on the perspective of digitalized engagement (PDE), the authors confirm the mediating effects on the e-brand equity-repurchase intention link while evidencing both positive and negative effects of WPPP on the linkage of e-brand equity and mediators. Contributions to theory, practice, and future studies are also provided.  相似文献   

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