Design and manufacture of high-filling-efficiency microfluidic devices

In this study, we proposed an efficient method for mass production of high-filling-efficiency microfluidic devices. Precision machining was the main process of device fabrication. The commercially available SolidWorks software was adopted for structure design. Unigraphics software was then used to simulate the machining process. The simulated tooling file was then loaded into a CNC milling machine for mold production. The fabricated metal mold was used for pouring polydimethylsiloxane (PDMS) to obtain high-filling-efficiency microfluidic structures. Finally, plasma-assisted packaging was conducted to tightly bind the PDMS microfluidic structure to the glass substrate. Experimental results showed that the additional semicircular filling structure and expended fill-entry structure can efficiently enhance filling efficiency of the microchannel device. The incubation well array can be completely filled at a relatively short filling time. The proposed highly efficient filling microfluidic device possesses advantages, such as feasibility for mass production and cost effectiveness.     

A Comparative Study on Open Circuit Voltage Models for Lithium-ion Batteries

The current research of state of charge(SoC) online estimation of lithium-ion battery(LiB) in electric vehicles(EVs)mainly focuses on adopting or improving of battery models and estimation filters. However, little attention has been paid to the accuracy of various open circuit voltage(OCV) models for correcting the SoC with aid of the ampere-hour counting method. This paper presents a comprehensive comparison study on eighteen OCV models which cover the majority of models used in literature. The low-current OCV tests are conducted on the typical commercial LiFePO_4/graphite(LFP) and LiNiMnCoO_2/graphite(NMC) cells to obtain the experimental OCV-SoC curves at different ambient temperature and aging stages. With selected OCV and SoC points from experimental OCV-SoC curves, the parameters of each OCV model are determined by curve fitting toolbox of MATLAB 2013. Then the fitting OCV-SoC curves based on diversified OCV models are also obtained. The indicator of root-mean-square error(RMSE) between the experimental data and fitted data is selected to evaluate the adaptabilities of these OCV models for their main features, advantages,and limitations. The sensitivities of OCV models to ambient temperatures, aging stages, numbers of data points,and SoC regions are studied for both NMC and LFP cells. Furthermore, the influences of these models on SoC estimation are discussed. Through a comprehensive comparison and analysis on OCV models, some recommendations in selecting OCV models for both NMC and LFP cells are given.     

Tribological Characteristics of Aqueous Graphene Oxide,Graphitic Carbon Nitride,and Their Mixed Suspensions

The tribological performance of graphene oxide (GO), graphitic carbon nitride (g-C₃N₄), and their mixed (g-C₃N₄/GO) aqueous suspensions was investigated. The 0.06 wt% GO, 0.06 wt% g-C₃N₄, and 0.06 wt% 1:1 g-C₃N₄/GO suspensions reduced the coefficient of friction (COF) by 37, 26 and 37% and wear mark radius by 19.1, 16.0 and 19.6%, respectively, in comparison with water. Pure g-C₃N₄ and GO suspensions showed unstable lubrication in the tests with relatively high loads and speeds, while the g-C₃N₄/GO mixed suspension had superior tribological performance in all tested conditions. This is because in the mixed suspension g-C₃N₄ agglomerates became smaller, and GO nanosheets exhibited fewer wrinkles and less stacking, which enabled the formation of a layer of tribo-composite film. As a result, the friction, wear and tribo-corrosion were reduced during sliding.     

Minireview: Methodology and instrumentation to evaluate critical pressure and temperature parameters

Critical parameters, such as critical temperatures, pressures, and densities, are basic in the development of supercritical fluid technology. However, the number of compounds for which critical parameters has been determined and has been limited by the current technology and the sensitivity of compound information to the external environment in a critical state. This paper provides an overview of the principles, key equipment, and methodologies to measure the critical parameters of compounds. The reliability of various determination methods is discussed, and future research into methods to determine critical compound parameters is suggested.     

Surface and chemical diffusion effects of nanowire electrodes in lithium-ion batteries

Science China Technological Sciences - Nanostructured electrodes with surface effect show a distinct advantage in prolonging the lifetime of lithium-ion (Li-ion) battery. In order to characterize...     

Meta photonic crystal paper devices

Science China Technological Sciences -     

一种基于传感器数据综合处理算法

提出基于知识参量的数据标准化处理方法,介绍了知识参量的构成以及故障征兆的隶属度表示方法.根据功率相等的原则提出了传感器数据中的野值滤波方法.运用神经网络和最小二乘法加权的方法对缺损数据进行填充,并分别与最小二乘法和BP网络的处理结果进行比较.仿真结果表明,运用该方法进行数据处理,可以在保证数据完整准确的情况下,有效地弥补原始数据的缺陷,提高了数据的准确性和可信度.     

COUPLING MODEL OF TWO PHASE FLOW IN A FRACTURE-ROCK MATRIX SYSTEM AND ITS STOCHASTIC FEATURE ANALYSIS

This study is concerned with developing a two-dimensional two-phase model thatsimulate the movement of non-aqueous phase liquid (NAPL) in a fracture-rock matrix system. Theintrinsic permeability and the fracture aperture are represented in the model via its Karhunen-Loeve expansion. Other parameters and the nodal unknowns, water saturations and waterpressures, are represented by their stochastic spectral expanions. The errors resulting fromtruncation of Karhunen - Loeve and polynomial chaos expansions to a finite number of terms areanalyzed. The eigenvalues of stochastic process is found out for any point in the special domain ofthe problem at any instant in time.     

水雷声引信系统海试考核方法探讨

对水雷声引信系统海上试验的考核方法进行了探讨,重点介绍了战技指标的概念和定义,并针对主要指标要求,分别详细介绍了考核评判标准。     

基于等效线性化的悬架力学参数设计

大部分独立悬架导向机构会造成悬架弹性元件的刚度、阻尼元件的阻尼与悬架刚度、阻尼之间产生非线性关系,并且随悬架动挠度的增大而变得更加明显,因此用线性模型在静态位置对悬架参数进行设计计算将造成较大的误差;基于虚位移原理分析了这种非线性关系,并运用等效线性化方法在经典平顺性分析的基础上给出了一种悬架参数设计方法,最后编写了数值求解程序进行计算。