The Motion Analysis of Nonrigid Membranes

In this paper we discuss the problem of determining the shape and motion of a nonrigid 2-dimensional membrane, and specific information about the physics of the membrane, from a sequence of monocular perspective images of the membrane in motion, initial and terminal depth information, and generic information about the physics of the membrane. We model a nonrigid 2-dimensional membrane by a surface without thickness, and the motion of a membrane by a second-order partial differential equation (PDE). We fit a family of surfaces to the image data and use initial and terminal depth information—together with the PDE—to determine both the position of the membrane at intermediate times and the constants that characterize membrane physics. The techniques presented have been applied to real membranes, and implementation results are presented.     

一种悬浮石墨烯压力传感器的制造与建模

提出了一种适用于纳机电系统(NEMS)的悬浮石墨烯压力传感器,并结合传统微机械加工工艺提出了压力传感器的制造过程。利用拉曼光谱表征了机械剥离法得到的不同厚度的石墨烯薄膜,验证了石墨烯"G"峰与"2D"峰的强度与薄膜厚度有关。基于薄膜膨胀试验方法,给出了悬浮于矩形、方形与圆形3种空腔的石墨烯薄膜的最大变形与压差的关系,并分别计算了3种形状下薄膜的压力灵敏度,可知矩形情况下单层石墨烯薄膜的压力灵敏度最大,当矩形宽度、方形边长或圆形直径越大,薄膜厚度越小时,压力灵敏度越高,计算表明:这种压力传感器具有高灵敏度。     

Parametric active membrane for segmentation of multiple objects in an image

We propose a topology adaptive active membrane that can segment images of multiple objects present in a scene. The parametric active membrane evolves in image space and splits into multiple membranes. The shape of the membrane can be constrained according to the shape of the objects present in a scene. We have shown that this active membrane model is also suitable for segmenting images of touching objects. The proposed segmentation technique unifies the membrane evolution and membrane splitting process. The methodology is tested for a number of real images from biomedical and machine vision domains that demonstrate the efficacy of the proposed scheme.     

膜生物反应器及其控制系统的应用研究

膜生物反应器是一种由膜分离单元与生物处理单元相结合的新型水处理技术,可靠高效的自动控制系统不仅能保证膜生物反应器的正常运行,还能降低其运行成本,延长膜通量和膜的使用寿命。本文以四川科学城医院膜生物反应器污水处理系统为例,讨论了膜生物反应器在处理医院废水中的应用,并介绍了适用于膜生物反应器的控制策略及控制系统。     

PEMFC电解质膜湿度控制方法研究

质子交换膜燃料电池电解质膜的湿度对其性能有非常大的影响。文章首先分析了影响电解质膜湿度的各种因素,提出了加湿O2控制PEMFC电解质膜湿度的办法;然后,建立了基于人工神经网络的PEMFC电解质膜湿度控制模型,并给出了控制电解质膜湿度的方法;最后,分析了控制方法的可行性。     

Optimal control of active transport across a biological membrane

We propose an optimal control principle for active transport across a biological membrane. The modeling of the membrane is based on Hill and Kedem's thermodynamic model. The performance function used to evaluate the optimality of the transport involved the rate of time-dependent changes in the concentration of particles in all the membrane layers as the state variables, and the number of receptor sites on the membrane as the control input. We decided that the optimal transport state is achieved when this cost function has been minimized under the constraints of the system equations characterizing the membrane modeling. The changes in the number of particles in the membrane layer evoked by changes in the kinetic parameters can be explained by the compensatory action of the optimal control strategy in order to prevent excessive decrease or increase of the molecular particles in all the membrane layers. The changes in the number of receptors in the paths of some physiological states can be explained by the optimal control modeling of the membrane transport. This model will be made available to create and evaluate an artificial membrane. This work was presented, in part, at the International Symposium on Artificial Life and Robotics, Oita, Japan, February 18–20, 1996     

用直接实验设计方法优化聚丙烯腈基膜的制备条件

以聚丙烯腈为聚合物，磷酸或聚乙二醇-600为添加剂，N-甲基吡咯烷酮为溶剂，采用L-S相转换法制备PAN超滤膜。利用计算机直接实验设计方法设计制膜的配方，用Statistic Analytic System(SAS)统计软件对膜的水通量、牛血清蛋白截留率和平均孔径进行回归分析，得出影响PAN基底膜性能的主要因素，并且优化了PAN基膜制备的工艺条件。实验结果表明，PAN浓度、添加剂种类和添加剂浓度是PAN基膜性能的主要影响因素；在一定的浓度范围内，以适当的PAN浓度和添加剂浓度均可制备出渗透性能较好的PAN超滤膜；SAS统计软件对PAN基膜的截留率和平均孔径的预测值与实验值吻合较好。     

明胶作载体的葡萄糖氧化酶电极性能的研究

本文介绍将葡萄糖氧化酶和明胶载体在少量甘油存在下,用戊二醛共聚合在聚丙烯透气膜上制作葡萄糖氧化酶膜.用此酶膜与pO_2传感器组装的酶电极本身含有足够量的氧,能使样品中氧含量对电极响应的依赖关系减小到最小.对该酶电极的最佳测试条件与分析特性作了测定,结果证明该电极可用于葡萄糖的检测.     

Analytical model of electrostatic actuators for micro gas pumps

We analytically predict the performance of electrostatic actuators for diaphragm micro gas pumps by combining energy minimization and the analytical solution for membrane deformation under uniform pressure. The tangential strain of the membrane is considered in the calculation of membrane deflection. Models for both single- and double-cavity pumps are established to define the restriction of the upper cavity on the membrane during actuation. The shape lines of the membrane in a double-cavity structure are demonstrated under different voltages. The influence of dielectric thickness and cavity geometry on pumping consequence is also discussed. In accordance with other simulation results on diaphragm displacement and chamber pressure rise, an electrostatic diaphragm micro gas pump with a relatively thin dielectric layer and a cavity of comparatively small depth and radius suitably generates high pressure rise. Furthermore, a double-cavity structure enhances pressure rise for the restriction of the upper cavity on the membrane during deformation.     

Development of a wrinkling algorithm for orthotropic membrane materials

Membrane constructions are still attractive an many fields of engineering applications. Especially the ongoing development and improvement of membrane materials instigates improved and new applications for membrane constructions. A commonly known problem while investigating membrane structures is the well wrinkling phenomena. In this work, we present and compare robust algorithms to predict wrinkled regions within complex membrane structures. Special focus is set on the application to isotropic and orthotropic membrane material formulations. As reference the solution of a 3-d shear test calculation is used. Special focus is set on the local and global characteristics of wrinkling. Examples demonstrate the potential of the used approaches.     

Insertion of X-ray structures of proteins in membranes

Few structures of membrane proteins are known and their relationships with the membrane are unclear. In a previous report, 20 X-ray structures of transmembrane proteins were analyzed in silico for their orientation in a 36A-thick membrane [J. Mol. Graph. Model. 20 (2001) 235]. In this paper, we use the same approach to analyze how the insertion of the X-ray structures varies with the bilayer thickness. The protein structures are kept constant and, at each membrane thickness, the protein is allowed to tilt and rotate in order to accommodate at their best. The conditions are said to be optimal when the energy of insertion is minimal. The results show that most helix bundles require thicker membranes than porin barrels. Moreover, in a few instances, the ideal membrane thickness is unrealistic with respect to natural membranes supporting that the X-ray structure requires adaptation to stabilize in membrane. For instance, the squalene cyclase could adapt by bending the side chains of its ring of lysine and arginine in order to increase the hydrophobic surface in contact with membranes. We analyzed the distribution of amino acids in the water, interface and acyl chain layers of the membrane and compared with the literature.     

温度敏感型高分子膜特性在线测试新方法的研究

温度溶胀性是温度敏感型高分子膜作为智能感应材料的关键特性。研究提出用压电悬臂梁换能器在溶液中在线测试高分子膜的温度溶胀特性。该测试装置由集成压电元件的悬臂梁和高分子膜探针两部分组装而成。高分子膜可以采用不同的化学处理方法固定在探针上。悬臂梁压电元件将高分子膜微小质量的变化转化为压电元件电气阻抗的变化。首先用有限元分析方法和实验方法校准自制压电悬臂梁的频率特性,从理论上得出压电导抗的频率变化与高分子膜质量变化的关系;然后用此装置在溶液中测试了粘贴膜和涂敷膜的温度溶胀特性;结果清晰地表明了高分子膜的低温亲水性和高温疏水性。压电悬臂结构换能器能具有在线正确地测定高分子膜的温度溶胀特性,具有很好的应用前景。     

ST切型石英膜片的应力分析

通常石英膜片的应力分布是根据弹性力学薄板弯曲理论分析得到的,但所选模型及边界条件相对简单,不能满足实际工程的需要.文中的ST切型石英膜片的边界条件复杂,用弹性力学薄板弯曲理论是很难得出结果的,为此采用了有限元法对ST切型石英膜片进行应力分析,并根据其应力分布规律,得出合理安放SAW(表面波)谐振器的位置.     

Computer simulation studies on significance of lipid polar head orientation

Models of lipid bilayer were extended and dipole structure of polar head in lipid molecules was included. As a result a wavy structure, resembling experimentally observed 'ripple phase', was obtained. The discussion on significance of interactions between dipoles that constitute polar part of the model membrane is presented. Assumptions of the model are closer to the real conditions and reflect the real phenomena much better. Dependence of the model system behaviour on dielectric permeability, ionic strength, and temperature was studied. An influence of reduced number of freedom degrees in the dipole system on the membrane properties was also considered. It was proved that if dielectric permeability of membrane polar part is significantly smaller than water dielectric permeability then the membrane model does not have to take into account changeability of dipole tilt towards membrane surface. This assumption becomes more significant for dielectric permeability epsilon approaching epsilon = 80. Packing degree of hydrocarbon chains in hydrophobic part of the membrane is also responsible for the angle value between dipoles and the membrane surface. The model results are compared to experimental results obtained by means of fluorescence probe fluorescein-PE.     

A multi-objective membrane algorithm guided by the skin membrane

Multi-objective optimization problems exist widely in the field of engineering and science. Many nature-inspired methods, such as genetic algorithms, particle swarm optimization algorithms and membrane computing model based algorithms, were proposed to solve the problems. Among these methods, membrane computing model based algorithms, also termed membrane algorithms, are becoming a current research hotspot because the successful linkage of membrane computing and evolutionary algorithms. In the past years, a lot of effective multi-objective membrane algorithms have been designed, where the skin membrane was often only used as an archive to store good solutions. In this paper, we propose an effective multi-objective membrane algorithm guided by the skin membrane, named SMG-MOMA, where the information of solutions stored in the skin membrane is used to guide the evolution of internal membranes. A skin membrane guiding strategy is suggested by allocating the solutions in skin membrane to internal membranes. Experimental results on ZDT and DTLZ benchmark multi-objective problems show that the proposed algorithm outperforms the-state-of-the-art multi-objective optimization algorithms.     

一种利用膜计算求解高维函数的全局优化算法

鉴于传统优化算法在求解高维多模态优化问题时存在收敛速度慢,求解精度低的缺点,针对上述问题提出了一种基于膜计算的优化算法。算法首先对高维空间进行分割,分割后每个子空间作为一个基本膜,基本膜区域中采用差分局部搜索策略提高算法的局部搜索能力和收敛速度。基本膜区域将局部最优解定时传送给表层膜。表层膜区域中采用全局搜索策略寻找全局最优解。通过对5个benchmark函数仿真验证,实验结果表明,该算法在收敛速度,求解精度和稳定性方面都有较大优势。     

基于特征提取的中药水提液膜分离预测系统

为了找出中药水提液膜过程中影响膜污染的主要因素和预测膜污染的程度以防止膜污染,提出了应用遗传神经网络提取影响中药水提液膜分离过程的特征因素的方法,并以特征因素为输入向量,使用神经网络、支持向量机等建立预测模型,开发并实现了集成化的综合分析和预测系统.介绍了中药水提液膜分离预测系统的体系结构、主要功能、运行情况及开发的关键技术.实验结果表明,该集成化的综合分析系统较单一分析建模预测精度更高.     

BP神经网络在中药水提液膜过滤中的应用

为防治中药水提液在无机陶瓷膜过滤中的膜污染问题,采用MATLAB编程实现了BP神经网络算法,并以反映中药水提液膜过程中的特征实验数据为训练样本建立网络模型.应用模型可预测反映水提液过滤时膜污染程度的指标参数--膜通量和膜污染度,从而为膜污染防治提供理论依据.网络的训练速度及预测结果表明,算法收敛速度较快,预测精度达到要求,为中药水提液膜过滤复杂系统中的膜污染程度预测提供了一种新思路和新方法.     

Analytical model of electrostatic actuators for micro gas pumps

We analytically predict the performance of electrostatic actuators for diaphragm micro gas pumps by combining energy minimization and the analytical solution for membrane deformation under uniform pressure. The tangential strain of the membrane is considered in the calculation of membrane deflection. Models for both single- and double-cavity pumps are established to define the restriction of the upper cavity on the membrane during actuation. The shape lines of the membrane in a double-cavity structure are demonstrated under different voltages. The influence of dielectric thickness and cavity geometry on pumping consequence is also discussed. In accordance with other simulation results on diaphragm displacement and chamber pressure rise, an electrostatic diaphragm micro gas pump with a relatively thin dielectric layer and a cavity of comparatively small depth and radius suitably generates high pressure rise. Furthermore, a double-cavity structure enhances pressure rise for the restriction of the upper cavity on the membrane during deformation.

     

聚合物在pH-ISFET研究中的应用

聚合物具有许多无机物没有的特性,已被越来越多地应用到pH-ISFET中,主要体现在4个方面,即pH敏感膜、pH钝化膜、结构材料及封装材料。在介绍pH-ISFET工作机理的基础上,分析了其对功能薄膜的要求,总结、比较了各种用于pH-ISFET的聚合物的特性、制备方法及其应用。