Layer-block tectonics of Cenozoic basements and formation of intra-plate basins in Nansha micro-plate, southern South China Sea

Layer-block tectonics （LBT） concept, with the core of pluralistic geodynamic outlook and multilayer-sliding tectonic outlook, is one of new keys to study 3-dimensional solid and its 4-dimensional evolution history of global tectonic system controlled by global geodynamics system. The LBT concept is applied to study the lithospheric tectonics of the southern South China Sea （SCS）. Based on the analysis of about 30 000 km of geophysical and geological data, some layer-blocks in the Nansha micro-plate can be divided as Nansha ultra-crustal layer-block, Zengmu crustal layer-block, Nanwei （Rifleman bank）-Andu （Ardasier bank） and Liyue （Reed bank） North Palawan crustal layer-blocks, Andu-Bisheng and Liyue-Banyue basemental layer-blocks. The basic characteristics of the basemental layer-blocks have been dicussed, and three intra-plate basin groups are identified. The intra-plate basins within Nansha micro-plate can be divided into three basin groups of Nanwei- Andu, Feixin-Nanhua, and Liyue-North Palawan based on the different geodynamics. In the light of pluralistic geodynamic concept, the upheaving force induced by the mid-crust plastic layer is proposed as the main dynamical force which causes the formation of the intra-plate basins within the Nansha micro-plate. Finally, models of a face-to-face dip-slip detachment of basemental layerblock and a unilateral dip-slip-detachment of basemental layer-block are put forward for the forming mechanisms of the Nanwei Andu and Liyue-North Palawan intra-plate basin groups, respectively.

Optimization of Sound Absorption and Insulation Performances of a Dual-Cavity Resonant Micro-Perforated Plate

This study investigates a dual-cavity resonant composite sound-absorbing structure based on a micro-perforated plate.Using the COMSOL impedance tube model,the effects of various structural parameters on sound absorption and sound insulation performances are analyzed.Results show that the aperture of the micro-perforated plate has the greatest influence on the sound absorption coefficient;the smaller the aperture,the greater is this coefficient.The thickness of the resonance plate has the most significant influence on the sound insulation and resonance frequency;the greater the thickness,the wider the frequency domain in which sound insulation is obtained.In addition,the effect of filling the structural cavity with porous foam ceramics has been studied,and it has been found that the porosity and thickness of the porous material have a significant effect on the sound absorption coefficient and sound insulation,while the pore size exhibits a limited influence.

Size-dependent effect on biaxial and shear nonlinear buckling analysis of nonlocal isotropic and orthotropic micro-plate based on surface stress and modified couple stress theories using differential quadrature method

The size-dependent effect on the biaxial and shear nonlinear buckling analysis of an isotropic and orthotropic micro-plate based on the surface stress, the modified couple stress theory （MCST）, and the nonlocal elasticity theories using the differential quadrature method （DQM） is presented. Main advantages of the MCST over the classical theory （CT） are the inclusion of the asymmetric couple stress tensor and the consideration of only one material length scale parameter. Based on the nonlinear von Karman assumption, the governing equations of equilibrium for the micro-classical plate consid- ering midplane displacements are derived based on the minimum principle of potential energy. Using the DQM, the biaxial and shear critical buckling loads of the micro-plate for various boundary conditions are obtained. Accuracy of the obtained results is validated by comparing the solutions with those reported in the literature. A parametric study is conducted to show the effects of the aspect ratio, the side-to-thickness ratio, Eringen＇s nonlocal parameter, the material length scale parameter, Young＇s modulus of the surface layer, the surface residual stress, the polymer matrix coefficients, and various boundary conditions on the dimensionless uniaxial, biaxial, and shear critical buckling loads. The results indicate that the critical buckling loads are strongly sensitive to Eringen＇s nonlocal parameter, the material length scale parameter, and the surface residual stress effects, while the effect of Young＇s modulus of the surface layer on the critical buckling load is negligible. Also, considering the size dependent effect causes the increase in the stiffness of the orthotropic micro-plate. The results show that the critical biaxial buckling load increases with an increase in G12/E2 and vice versa for E1/E2. It is shown that the nonlinear biaxial buckling ratio decreases as the aspect ratio increases and vice versa for the buckling amplitude. Because of the most lightweight micro-composite materials with high strength/weight and stiffness/weight ratios, it is anticipated that the results of the present work are useful in experimental characterization of the mechanical properties of micro-composite plates in the aircraft industry and other engineering applications.

Discharge characteristics of a needle-to-plate electrode at a micro-scale gap

To understand the discharge characteristics under a gap of micrometers,the breakdown voltage and current–voltage curve are measured experimentally in a needle-to-plate electrode at a microscale gap of 3–50 μm in air.The effect of the needle radius and the gas pressure on the discharge characteristics are tested.The results show that when the gap is larger than 10 μm,the relation between the breakdown voltage and the gap looks like the Paschen curve;while below 10 μm,the breakdown voltage is nearly constant in the range of the tested gap.However,at the same gap distance,the breakdown voltage is still affected by the pressure and shows a trend similar to Paschen＇s law.The current–voltage characteristic in all the gaps is similar and follows the trend of a typical Townsend-to-glow discharge.A simple model is used to explain the non-normality of breakdown in the micro-gaps.The Townsend mechanism is suggested to control the breakdown process in this configuration before the gap reduces much smaller in air.

Nonlinear vibration analysis of laminated composite Mindlin micro/nano-plates resting on orthotropic Pasternak medium using DQM

The nonlocal nonlinear vibration analysis of embedded laminated micro- plates resting on an elastic matrix as an orthotropic Pasternak medium is investigated. The small size effects of micro/nano-plate are considered based on the Eringen nonlocal theory. Based on the orthotropic Mindlin plate theory along with the von Kármán geo- metric nonlinearity and Hamilton＇s principle, the governing equations are derived. The differential quadrature method （DQM） is applied for obtaining the nonlinear frequency of system. The effects of different parameters such as nonlocal parameters, elastic me- dia, aspect ratios, and boundary conditions are considered on the nonlinear vibration of the micro-plate. Results show that considering elastic medium increases the nonlinear frequency of system. F^lrthermore, the effect of boundary conditions becomes lower at higher nonlocal parameters.

A Monolithic, FEM-Based Approach for the Coupled Squeeze Film Problem of an Oscillating Elastic Micro-Plate Using 3D 27-Node Elements

In this study we describe an FEM-based methodology to solve the coupled fluid-structure problem due to squeeze film effects present in vibratory MEMS devices, such as resonators, gyroscopes, and acoustic transducers. The aforementioned devices often consist of a plate-like structure that vibrates normal to a fixed substrate, and is generally not perfectly vacuum packed. This results in a thin film of air being sandwiched between the moving plate and the fixed substrate, which behaves like a squeeze film offering both stiffness and damping. Typically, such structures are actuated electro-statically, necessitating the thin air gap for improving the efficiency of actuation and the sensitivity of detection. To accurately model these devices the squeeze film effect must be incorporated. Extensive literature is present on mod- eling squeeze film effects for rigid motion for both perforated as well as non-perforated plates. Studies which model the plate elasticity often use approximate mode shapes as input to the 2D Reynolds Equation. Recent works which try to solve the coupled fluid elasticity problem, report iterative FEM-based solution strategies for the 2D Reynolds Equation coupled with the 3D elasticity Equation. In this work we present a FEM-based single step solution for the coupled problem at hand, using only one type of element (27 node 3D brick). The structure is modeled with 27 node brick elements of which the lowest layer of nodes is also treated as the fluid domain (2D) and the integrals over fluid domain are evaluated for these nodes only. We also apply an electrostatic loading to our model by considering an equivalent electro-static pressure load on the top surface of the structure. Thus we solve the coupled 2D-fluid-3D-structure problem in a single step, using only one element type. The FEM results show good agreement with both existing analytical solutions and published experimental data.

Analytical Modeling of Vibration of Micropolar Plates

This paper presents an extension of mathematical static model to dynamic problems of micropolar elastic plates, recently developed by the authors. The dynamic model is based on the generalization of Hellinger-Prange-Reissner (HPR) variational principle for the linearized micropolar (Cosserat) elastodynamics. The vibration model incorporates high accuracy assumptions of the micropolar plate deformation. The computations predict additional natural frequencies, related with the material microstructure. These results are consistent with the size-effect principle known from the micropolar plate deformation. The classic Mindlin-Reissner plate resonance frequencies appear as a limiting case for homogeneous materials with no microstructure.

Bending strength degradation of a cantilever plate with surface energy due to partial debonding at the clamped boundary

This paper investigates the bending fracture problem of a micro/nanoscale cantilever thin plate with surface energy,where the clamped boundary is partially debonded along the thickness direction.Some fundamental mechanical equations for the bending problem of micro/nanoscale plates are given by the Kirchhoff theory of thin plates,incorporating the Gurtin-Murdoch surface elasticity theory.For two typical cases of constant bending moment and uniform shear force in the debonded segment,the associated problems are reduced to two mixed boundary value problems.By solving the resulting mixed boundary value problems using the Fourier integral transform,a new type of singular integral equation with two Cauchy kernels is obtained for each case,and the exact solutions in terms of the fundamental functions are determined using the PoincareBertrand formula.Asymptotic elastic fields near the debonded tips including the bending moment,effective shear force,and bulk stress components exhibit the oscillatory singularity.The dependence relations among the singular fields,the material constants,and the plate's thickness are analyzed for partially debonded cantilever micro-plates.If surface energy is neglected,these results reduce the bending fracture of a macroscale partially debonded cantilever plate,which has not been previously reported.

应用Micro CT测量下颌第二磨牙牙根尖到颊侧骨板的距离

目的运用Micro CT技术测量牙根尖到颊侧骨板的解剖距离。方法应用Micro CT(Skyscan 1072,Antwerpen,Belgium)及cutome计算机软件分析三维骨结构。结果下颌第二磨牙,近中根和远中根到颊侧骨板的距离平均为5.18mm和4.09mm。上颌骨的颊根中,上颌第二磨牙近中颊根和远中颊根到颊侧骨板的距离最大,分别是4.63mm和3.61mm。结论Micro CT是一种快速、准确、不损伤样本内部结构有效的评价方法。

Transient electro-osmotic and pressure driven flows of two-layer fluids through a slit microchannel

By method of the Laplace transform, this arti- cle presents semi-analytical solutions for transient electro- osmotic and pressure-driven flows （EOF/PDF） of two-layer fluids between microparallel plates. The linearized Poisson- Boltzmann equation and the Cauchy momentum equation have been solved in this article. At the interface, the Maxwell stress is included as the boundary condition. By numerical computations of the inverse Laplace transform, the effects of dielectric constant ratio e, density ratio p, pressure ratio p, viscosity ratioμ of layer II to layer I, interface zeta potential difference △ψ, interface charge density jump Q, the ratios of maximum electro-osmotic velocity to pressure velocity , and the normalized pressure gradient B on transient veloc- ity amplitude are presented.We find the velocity amplitude becomes large with the interface zeta potential difference and becomes small with the increase of the viscosity. The ve- locity will be large with the increases of dielectric constant ratio; the density ratio almost does not influence the EOF ve- locity. Larger interface charge density jump leads to a strong jump of velocity at the interface. Additionally, the effects of the thickness of fluid layers （hi and h2） and pressure gradient on the velocity are also investigated.

Spectrophotometric Study for the Reaction of Pentoxifylline Hydrochloride with 1,2-Naphthoquinone-4-Sulphonate: Kinetics, Mechanism and Application for Development of High-Throughput Kinetic Microwell Assay for Pentoxifylline in Quality Control Laboratory

Spectrophotometric study was carried out, for the first time, to investigate the reaction between the vasodilator pentoxifylline hydrochloride (POX) and 1,2-naphthoquinone-4-sulphonate (NQS) reagent. The reaction occurs in alkaline medium to activate the nucleophilic substitution reaction producing an orange-colored product measured spectrophometrically at λmax 472 nm. The variables affecting the reaction were carefully studied and the conditions were optimized. The kinetics of the reaction was investigated and its activation energy was found to be 0.262 cal/mol. Owing to its low activation energy, the reaction proceeded easily and was successfully used for simple and rapid assay of POX. The stoichiometry of the reaction was determined (1:1), and the reaction mechanism was suggested. To develop a high-throughput methodology used in quality control laboratory, a comparative study of the reaction using the conventional spectrophotometric versus microwell assay was applied. Under the optimum reaction conditions, the initial rate and fixed time methods were utilized for constructing the calibration graphs for determination of POX concentrations. The linear range was 10 - 120 μg/ml with good correlation coefficients (0.9987 - 0.9998). The LOD was 2.5 and 3.4 μg/ml for initial rate and fixed time methods, respectively. The intra- and inter-day accuracy and precision of the developed methods were satisfactory, where RSD was ≤3.94%. The present methods have been successfully applied to the determination of POX in its pharmaceutical tablets, and the percentage recovery values were 97.9% - 101.9%. Therefore, we strongly recommend the proposed methods for determination of POX in quality control laboratories.

轴向柱塞泵配流副椭圆开口偏置类抛物线微织构多目标优化

为了提高轴向柱塞泵配流副承载性能、抗摩擦磨性能及容积效率,以某型斜盘式轴向柱塞泵配流盘为原型开展研究。首先,依据正交实验理论采用CFD方法研究椭圆开口偏置抛物线微织构(Elliptic opening offset parabola micro texture, EOOPT)形状参数对轴向柱塞泵配流副承载压强、摩擦因数的影响规律,并联合运用神经网络和遗传算法对EOOPT的形状参数进行优化设计。其次,运用响应面分析方法研究EOOPT分布参数对配流副承载压强、摩擦因数和泄漏量的影响规律,并对形状参数进行优化设计。最后对最优特征参数EOOPT织构化的柱塞泵配流副和未织构的相关性能进行对比分析,结果表明,前者的承载压强较后者提高11.23%,摩擦因数和泄漏量分别减低16.67%和2.96%。

表面平齐的并联微穿孔板吸声结构特性仿真研究

针对火箭发动机燃气高温高速射流通道内噪声控制的工程需要,提出了一种表面平齐的并联微穿孔板吸声结构设计方案。基于微穿孔板吸声理论,建立了COMSOL微穿孔板吸声结构吸声性能仿真模型,对该类并联微穿孔板吸声结构的吸声特性进行了仿真研究,分析了并联结构的背腔深度比、周期和单体宽度等多种参数对吸声性能的影响。结果表明,通过合理选择微穿孔板参数,以及并联共振腔深度、周期比、单体宽度等参数,可以得到吸声带宽、吸声系数较优的吸声结构,且加工制造与安装维护简单,研究成果可用于高温高速射流通道内的强噪声辐射环境控制。

经三角肌入路微型锁定钢板内固定治疗肱骨大结节骨折

2019年8月~2021年3月,我科采用经三角肌入路微型锁定钢板内固定治疗16例肱骨大结节骨折患者,效果满意,报道如下。1材料与方法1.1病例资料本组16例,男10例,女6例,年龄19~58岁。均为新鲜闭合损伤。依据Neer分型均为二部分骨折。伤后至手术时间3~8 d。

后外侧入路微型锁定钢板治疗肱骨远端冠状面骨折

2018年6月~2021年9月,山西医科大学第二医院骨科采用后外侧入路微型锁定钢板内固定治疗9例肱骨远端冠状面骨折患者,疗效满意,报道如下。1材料与方法1.1病例资料本组9例,男3例,女6例,年龄26~61岁。左侧6例,右侧3例。骨折Dubberley分型:ⅠA型1例,ⅡA型3例,ⅡB型3例,ⅢB型2例。合并桡骨头骨折2例,外侧副韧带损伤1例,外上髁撕脱骨折1例。受伤至手术时间5~12 d。

轴向柱塞泵摩擦副理论与技术研究现状

轴向柱塞泵是液压系统中的核心动力部件,对液压控制系统有着举足轻重的意义。轴向柱塞泵中的三大摩擦副的润滑和摩擦特性影响着柱塞泵本身的性能和使用寿命。轴向柱塞泵三大摩擦副理论与技术的研究对于提升轴向柱塞泵性能和可靠性具有重要意义。梳理了轴向柱塞本三大摩擦副润滑理论和摩擦特性方面的理论与技术与提高摩擦副性能的表面改性工艺方法。

高阶微穿孔型超材料低频宽带吸声机理

针对现有低频噪声控制的迫切需要,提出了一种高阶微穿孔型超材料结构,解释了其低频宽带吸声机理,并设计了新型的高阶微穿孔型低频宽带吸声超材料,在300~3 000 Hz的频率范围内表现出连续优异的吸声特性。设计了单个单元的吸声结构,通过在传统的微穿孔超材料内部增加穿孔板的方式,激发高阶特性,对比发现,高阶微穿孔型超材料实现了对高阶峰值的灵活调整。使用理论公式和有限元仿真,建立单元结构的计算模型计算单元的吸声系数,对结构进行吸声机理分析,同时分析了典型结构参数对于吸声特性的影响规律;在此基础上,通过单元间的严格耦合,设计了一种9单元宽带吸声结构,并进行实验验证。实验结果表明,该材料总体厚度为106.1 mm,在300~3 000 Hz的频率范围内获得了连续优异的带宽,平均吸声系数达到90%以上。该结构具有亚波长厚度的低频宽带吸声特性,在汽车、飞机、轮船等噪声环境中,具有广阔的减震降噪的工程应用前景。

CMOS红外光源的设计与实现

基于红外气体传感器微型化、低成本和低功耗的发展需要,设计了一种用于非色散红外(NDIR)集成气体传感器的互补金属氧化物半导体(CMOS)红外光源。它以非等间隔的蛇形钨(W)薄膜电阻作为加热丝,以二氧化硅(SiO_(2))和氮化硅(Si_(3)N_(4))多层复合介质薄膜为支撑形成悬空膜片式微热板,以氧化铜(CuO)和二氧化锰(MnO_(2))纳米材料复合薄膜作为辐射增强层。基于COMSOL软件进行了热电耦合仿真,证明结构设计合理性。采用标准CMOS工艺、硅(Si)的深刻蚀工艺以及静电流体动力学打印技术流片制造了该CMOS红外光源芯片。性能测试结果表明:该红外光源从室温升温至469℃的热响应时间约为41 ms,电功耗仅为138 mW,辐射区温度分布均匀,引入辐射增强层使表面比辐射率提高约35%,红外光源的辐射功率和红外光谱辐射强度测试结果表明:该涂层有效地增强了红外辐射。

合成生物学表型测试生物反应器及其装备化研究进展

合成生物学经过多年的发展,形成了典型的细胞工厂创制“设计-构建-测试-学习”(design-build-testlearn,DBTL)循环,成为支撑面向加速生物制造发展的智慧生物育种的重要方法。其中,测试环节是对前期所设计与构建的生物体系进行表型测试,以提供大量数据用于后续的学习和迭代升级。测试阶段的通量主要依赖于细胞自身或其培养测试所使用的生物反应器及其装备,是整个DBTL流程的限速步骤。本文系统综述了合成生物学表型测试所开发的面向不同通量的生物反应器及装备,从单细胞检测和筛选及不同尺度生物反应器包括皮纳升级生物反应器、微升级生物反应器、毫升级生物反应器和升级生物反应器等,系统地介绍了各自的特点和应用场景。同时,指出了现有生物反应器及其装备的应用潜力、面临的挑战与发展趋势,为合成生物学表型测试技术研究提供重要参考。

微型钛板内固定在口腔颌面骨折效果中的应用价值

目的:分析微型钛板内固定在口腔颌面骨折治疗中的应用价值。方法:选取2020年4月至2021年7月于河南科技大学第一附属医院(开元院区)就诊的口腔颌面骨折患者80例,按照随机分组的方法将其分为微型钛板组和不锈钢板组,每组各40例。微型钛板组采用微型钛板内固定法进行治疗,不锈钢板组采用不锈钢板固定法进行治疗。比较两组患者口面部肌功能、骨折愈合情况、并发症发生情况。结果:手术后,两组患者唇姿势评分比较,差异无统计学意义(P> 0.05),微型钛板组患者外观与姿势其余项目评分、运动评分高于不锈钢板组,差异具有统计学意义(P <0.05)。微型钛板组患者张口度高于不锈钢板组,差异具有统计学意义(P <0.05)。两组患者咬合正常率比较,差异无统计学意义(P> 0.05)。微型钛板组患者并发症发生率低于不锈钢板组,差异具有统计学意义(P <0.05)。结论:微型钛板内固定与不锈钢板固定对咬合度均具有较好的临床效果,但微型钛板内固定能更有效地促进患者口面部肌功能的恢复,加快颌面骨折愈合速度,降低并发症发生率,利于患者术后恢复。