Shenyang Institute of Automation,Chinese Academy Of Sciences
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Measuring The Mechanical Properties of Cancerous Cells in Fluidic Environments by Atomic Force Microscopy
No full text目的细胞力学特性在细胞生理病理活动过程中起着重要的调控作用，开展细胞力学特性研究对于揭示生命活动内在规律具有重要意义。原子力显微镜(AFM)的发明为单细胞力学特性表征提供了新的强大工具，基于AFM压痕分析的细胞力学特性探测已成为生命科学领域的重要研究方法，为单细胞行为研究带来了大量新的认识。然而，现有基于AFM的细胞力学特性研究主要集中在静态溶液环境，而癌细胞在体内转移过程中处于脉管系统的动态液流环境下，因此现有的测量结果无法完全反映溶液流动环境下的癌细胞真实生理行为，特别是目前对于肿瘤转移过程中液流环境与癌细胞之间相互作用的力学机制的认知还十分有限。本文通过将AFM与液流控制技术结合建立了溶液流动环境下的细胞力学特性测量方法。方法基于两侧开口培养皿并结合注射泵/抽取泵液流控制搭建细胞培养基动态液流系统，并将其分别与AFM及光学倒置显微镜进行集成。选取MCF-7(人乳腺癌细胞)和HGC-27(人未分化胃癌细胞)两种癌细胞进行实验。利用细胞培养基动态液流系统培养细胞并分析溶液流速以及流动时间对细胞生长及力学特性的影响。在光学显微镜导引下控制AFM对培养基静态/流动环境下生长的细胞进行压痕实验以获取力曲线，并利用Hertz-Sneddon模型对力曲线进行分析得到细胞杨氏模量。利用荧光染色试剂分析溶液流动环境对细胞活性及细胞骨架蛋白的影响。结果首先分析了溶液流动环境对细胞生长的影响。实验结果表明，与静态培养环境相比，培养基动态液流环境可更好地促进细胞生长。随后分别对静态和流动环境下生长的癌细胞的力学特性进行了测量，结果表明当癌细胞生长环境由静态变为动态后细胞的杨氏模量显著减小，且溶液流动环境会导致细胞骨架结构的变化，显示了溶液流动环境对癌细胞力学特性的显著影响。结论将AFM与液流控制技术结合可对溶液流动环境下的单细胞力学特性进行探测，为研究溶液流动环境与癌细胞之间的相互作用提供了新的方法和思路。</p
Research Progress on Acoustic Model of Porous Sound Absorbing Materials and Measurement Method of Its Characteristic Parameters
No full text噪声是载人航天器的重要环境因素之一,航天器环境噪声升高会直接影响航天员工作和休息,进而影响空间科学任务。然而,以往在轨运行的载人航天器存在较多噪声过大的问题,多孔吸声材料已经在国际空间站应用并取得良好的降噪效果,我国空间站预计2022年底建成,了解声学多孔材的声学模型以及吸声机理对我空间站运营阶段的降噪具有重要的意义。基于刚性框架假设,多孔吸声材料声学等效模型分为经验模型和唯像模型,Delany-Bazley是常用的经验模型,采用此模型不能对多孔材料吸声的性能提供精确的预测,唯象模型考虑了声波在材料孔隙和空腔中的传播,可以准确预测吸声性能,因此Johnson-Champoux-Allard唯象模型被众多学者应用。流阻、孔隙率、曲率、粘胶特征长度和热特性长度等多孔材料声学特性参数是准确建立多孔材料Johnson-Champoux-Allard模型的关键,流阻测试方法包括直接气流法、声学阻抗管法、交流法和比较法;孔隙率的测试方法分为直接测试方法和声学阻抗管测试方法;曲率、粘性特征长度和热特性长度可以通过超声波进行直接测试,直接测量通常比较复杂、不太可靠并且具有破坏性,反演优化方法是获得多孔材料曲率、粘性特征长度和热特性长度的常用方法。本文概述了多孔吸声材料在国际空间站的应用情况,综述了多孔吸声材料声学等效模型的研究进展,介绍了多孔吸声材料吸声原理、声学扰动基本方程以及声学属性参数的测试方法,重点介绍了多孔吸声材料声学等效模型中的经验模型和唯像模型,进而对多孔材料声学等效模型中的声学特征参数的测试方法进行详细论述。</p
On a Nonlinear Non-Autonomous Ratio-Dependent Food Chain Model with Delays and Feedback Controls
No full text该文研究了一类具有时滞和反馈控制的三种群非线性非自治比率依赖的食物链模型.首先,基于时滞微分不等式理论,提出了一些新的分析方法,并构造了一个合适的李亚普诺夫函数.其次,得到了系统正解的持久性和全局吸引性的充分条件.第三,利用理论分析和不动点理论,讨论了相应的周期系统,建立了周期系统正周期解的存在性、唯一性和稳定性的充分条件.另外,给出了一些数值模拟,证明了我们的理论分析是正确的.最后,给出了相应的具有乘法噪声源的随机食物链模型的数值例子,并得到该模型一些新的有趣的解的变化过程.</p
An Overview of Underwater Vision Enhancement: From Traditional Methods to Recent Deep Learning
No full textUnderwater video images, as the primary carriers of underwater information, play a vital role in human exploration and development of the ocean. Due to the optical characteristics of water bodies, underwater video images generally have problems such as color bias and unclear image quality, and image quality degradation is severe. Degenerated images have adverse effects on the visual tasks of underwater vehicles, such as recognition and detection. Therefore, it is vital to obtain high-quality underwater video images. Firstly, this paper analyzes the imaging principle of underwater images and the reasons for their decline in quality and briefly classifies various existing methods. Secondly, it focuses on the current popular deep learning technology in underwater image enhancement, and the underwater video enhancement technologies are also mentioned. It also introduces some standard underwater data sets, common video image evaluation indexes and underwater image specific indexes. Finally, this paper discusses possible future developments in this area.</p
Medical image fusion via discrete stationary wavelet transform and an enhanced radial basis function neural network
No full textMedical image fusion of images obtained via different modes can expand the inherent information of original images, whereby the fused image has a superior ability to display details than the original sub-images, to facilitate diagnosis and treatment selection. In medical image fusion, an inherent challenge is to effectively combine the most useful information and image details without information loss. Despite the many methods that have been proposed, the effective retention and presentation of information proves challenging. Therefore, we proposed and evaluated a novel image fusion method based on the discrete stationary wavelet transform (DSWT) and radial basis function neural network (RBFNN). First, we analyze the details or feature information of two images to be processed by DSWT by using two-level decomposition to separate each image into seven parts, comprising both high-frequency and low-frequency sub-bands. Considering the gradient and energy attributes of the target, we substituted the pending parts in the same position in the two images by using the proposed enhanced RBFNN. The input, hidden, and output layers of the neural network comprised 8, 40, and 1 neuron(s), respectively. From the seven neural networks, we obtained seven fused parts. Finally, through inverse wavelet transform, we obtained the final fused image. For the neural network training method, the hybrid adaptive gradient descent algorithm (AGDA) and gravitational search algorithm (GSA) were implemented. The final experimental results revealed that the novel method has significantly better performance than the current state-of-the-art methods.</p
A humanoid robotic hand capable of internal assembly and measurement in spacesuit gloves
No full textPurpose To identify the dexterity of spacesuit gloves, they need to undergo bending tests in the development process. The ideal way is to place a humanoid robotic hand into the spacesuit glove, mimicking the motions of a human hand and measuring the bending angle/force of the spacesuit glove. However, traditional robotic hands are too large to enter the narrow inner space of the spacesuit glove and perform measurements. This paper aims to design a humanoid robot hand that can wear spacesuit gloves and perform measurements. Design/methodology/approach The proposed humanoid robotic hand is composed of five modular fingers and a parallel wrist driven by electrical linear motors. The fingers and wrist can be delivered into the spacesuit glove separately and then assembled inside. A mathematical model of the robotic hand is formulated by using the geometric constraints and principle of virtual work to analyze the kinematics and statics of the robotic hand. This model allows for estimating the bending angle and output force/torque of the robotic hand through the displacement and force of the linear motors. Findings A prototype of the robotic hand, as well as its testing benches, was constructed to validate the presented methods. The experimental results show that the whole robotic hand can be transported to and assembled in a spacesuit glove to measure the motion characteristics of the glove. Originality/value The proposed humanoid robotic hand provides a new method for wearing and measuring the spacesuit glove. It can also be used to other gloves for special protective suits that have highly restricted internal space
Correlative AFM and Scanning Microlens Microscopy for Time-Efficient Multiscale Imaging
No full textWith the rapid evolution of microelectronics and nanofabrication technologies, the feature sizes of large-scale integrated circuits continue to move toward the nanoscale. There is a strong need to improve the quality and efficiency of integrated circuit inspection, but it remains a great challenge to provide both rapid imaging and circuit node-level high-resolution images simultaneously using a conventional microscope. This paper proposes a nondestructive, high-throughput, multiscale correlation imaging method that combines atomic force microscopy (AFM) with microlens-based scanning optical microscopy. In this method, a microlens is coupled to the end of the AFM cantilever and the sample-facing side of the microlens contains a focused ion beam deposited tip which serves as the AFM scanning probe. The introduction of a microlens improves the imaging resolution of the AFM optical system, providing a 3–4× increase in optical imaging magnification while the scanning imaging throughput is improved ≈8×. The proposed method bridges the resolution gap between traditional optical imaging and AFM, achieves cross-scale rapid imaging with micrometer to nanometer resolution, and improves the efficiency of AFM-based large-scale imaging and detection. Simultaneously, nanoscale-level correlation between the acquired optical image and structure information is enabled by the method, providing a powerful tool for semiconductor device inspection.</p
Carbon Black/PDMS Based Flexible Capacitive Tactile Sensor for Multi-Directional Force Sensing
No full textFlexible sensing tends to be widely exploited in the process of human-computer interactions of intelligent robots for its contact compliance and environmental adaptability. A novel flexible capacitive tactile sensor was proposed for multi-directional force sensing, which is based on carbon black/polydimethylsiloxane (PDMS) composite dielectric layer and upper and lower electrodes of carbon nanotubes/polydimethylsiloxane (CNTs/PDMS) composite layer. By changing the ratio of carbon black, the resolution of carbon black/PDMS composite layer increases at 4 wt%, and then decreases, which was explained according to the percolation theory of the conductive particles in the polymer matrix. Mathematical model of force and capacitance variance was established, which can be used to predict the value of the applied force. Then, the prototype with carbon black/PDMS composite dielectric layer was fabricated and characterized. SEM observation was conducted and a ratio was introduced in the composites material design. It was concluded that the resolution of carbon sensor can reach 0.1 N within 50 N in normal direction and 0.2 N in 0-10 N in tangential direction with good stability. Finally, the multi-directional force results were obtained. Compared with the individual directional force results, the output capacitance value of multi-directional force was lower, which indicated the amplitude decrease in capacity change in the normal and tangential direction. This might be caused by the deformation distribution in the normal and tangential direction under multi-directional force
Energy-Based Motion Control for Pneumatic Artificial Muscle Actuated Robots With Experiments
No full textThe pneumatic artificial muscle (PAM) is a kind of flexible actuators used to simulate the characteristics of human muscles. Robots actuated by PAMs possess compliance and safety, which can achieve satisfactory man-machine interaction control. Nevertheless, such robots actuated by PAMs tend to have lots of control problems due to the inherent characteristics, such as hysteresis, creep, high nonlinearities, and so on, which is not conducive to accurate modeling and motion control. Moreover, most existing control methods do not consider constraining overshoots, etc.; however, based on safety requirements and actual physical constraints, systems with unconstrained overshoots may have potential risks. In this article, a new energy-based nonlinear control method is proposed for 2-link PAM-actuated robots to realize accurate positioning control. For this purpose, first, the dynamic model of 2-link PAM-actuated robots is presented. Further, a new energy storage function is constructed. Additionally, the overshoots and the terms coupled with control inputs are also constrained reasonably, which can reduce the unnecessary energy loss while improving the system safety. To the best of our knowledge, the proposed method is the first nonlinear control approach for 2-link PAM-actuated robots which is designed and analyzed based upon the original nonlinear dynamics without any linearization to provide high-performance positioning control with constrained overshoots and eliminated residual oscillations simultaneously. By rigorous analysis, the asymptotic stability of the system is proven. To validate the effectiveness of the proposed method, a series of hardware experimental results are presented based on a self-built 2-link PAM-actuated robot
Study on the Watertight Characteristics of Rubber-Molded Watertight Connector at Full-Ocean Depth
No full text全海深(11 000 m)橡胶体水密连接器是全海深潜水器的重要组成部分，它的水密性能是保证其正常运行的前提。研制了一种全海深橡胶体水密连接器，通过实验室测试与海上试验研究其水密特性。在实验室中127 MPa循环水压下测试其绝缘电阻大于1 000 MΩ,接触电阻约为4 mΩ;并且通过搭载试验装置与“奋斗者”号载人潜水器下潜完成10 909 m试验，搭载过程中性能良好，表明其能满足全海深的应用需求。</p