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1.
Nano-manipulation technology is an emerging field in the development of modern science and technology. Atomic force microscope （AFM）, a sharp weapon for nano imaging and nanomanipulation, which is honored as ＂eye＂ and ＂hand＂ of nano-technology. However, due to the hysteresis, creep and other nonlinearity of piezoelectric ceramics tube （PZT） as well as the probe＇s tip deviations caused by cantilever deformation, AFM has larger error of relative displacement between probe and sample, which creates enormous inconvenience to the nano-manipulation and repositioning. As to improve positioning accuracy, this dissertation presents a novel AFM＇s X-Y dimensional nano-positioning control system with large-scale based on H∞ control. Through careful research on variety of influence factors on AFM＇s precise nano-manipulation, a composite control strategy based on feedforward compensation control of cantilever probe tip＇s offset and H∞ control of piezoelectric scanner is presented in this paper. In the end, simulation results can also testify the tracking ability and better nano-positioning performance of the system. 相似文献
2.
辛冬梅 《上海大学学报(英文版)》2010,14(3):211-216
By introducing some parameters and estimating the weight function,we obtain an extension of reverse Hilbert-type inequality with the best constant factor.As applications,we build its equivalent forms and some particular results. 相似文献
3.
β-TCP ceramic scaffolds were fabricated with selective laser sintering(SLS)in this work. Carbon nanotubes(CNTs)were mixed with porous β-TCP matrix to enhance the mechanical performance of the bone tissue engineering scaffolds. Scaffold reconstruction and microstructure analysis were fulfilled based on micro-computed tomography(Micro-CT)scanning data.Results show that the strength of scaffold mixed with 0.2% CNTs reaches 0.819 MPa which has been improved by 85.7% compared with that without CNTs. Micro-CT analysis shows that the scaffold has a good interconnectivity, and pore size mainly distributes in the two regions of 60-340 μm and 500 620 μm. 相似文献
4.
黄昕龙花海燕陈世辉 《福建工程学院学报》2020,(6):524-529
产品的表面质量差严重制约了熔融沉积成型(fused deposition modeling,FDM)工艺的发展,通过粗糙度成型机理构建参数模型是提升FDM 成型件表面质量的重要途径。文章以某FDM 打印设备成型件的水平表面粗糙度为例,通过探讨参数三次曲线与多段直线拟合的丝宽模型,利用粗糙度的几何机理提出了基于3 个主要工艺参数的回归模型,采用样条变换的非线性偏最小二乘回归(partial least squares,PLSR)建立对所选参数的有效预测模型,并对建模中未覆盖的不同打印参数下的实验数据样本进行校验,分析工艺参数对水平表面粗糙度的影响。通过以上研究方法,提高了水平表面粗糙度预测效率,获取了相关的经验知识。 相似文献
5.
In this paper, the design and verification process of an automobile-engine-fan control system on chip （SoC） are introduced. The SoC system, SHU-MV08, reuses four new intellectual property （IP） cores and the design flow is accomplished with 0.35 btm chartered CMOS technology. Some special functions of IP cores, the detailed integration scheme of four IP cores, and the verification method of the entire SoC are presented. To settle the verification problems brought by analog IP cores, NanoSim based chip-level mixed-signal verification method is introduced. The verification time is greatly reduced and the first tape-out achieves success which proves the validity of our design. 相似文献
6.
Establishing an accurate in situ stress field is important for analyzing the rock-mass stability of the underground cavern at the Huangdeng hydropower station in China. Because of the complexity and importance of the in situ stress field, existing back analysis methods do not provide the necessary accuracy or sufficiently recognize nonlinear relations between the distribution of the in situ stress field and its formative factors. Those factors are related to the geological structures of high compressive tectonic stress regimes, including geological faults and tuff interlayers. The new two-stage optimization algorithm proposed in this paper is a combination of stepwise regression (SR), difference evolution (DE), support vector machine (SVM), and numerical analysis techniques. Stepwise regression is used to find the set of unknown parameters that best match the modeling prediction and determine the range of parameters to be recognized. Difference evolution is used to determine the optimum parameters of the SVM. The SVM is used to create the DE-SVM nonlinear reflection model to obtain the optimal values of the parameters from measured stress data. We compare the new two-stage optimization algorithm to other two popular methods, a multiple linear regression (MLR) analysis method and an artificial neural network (ANN) method, to estimate the in situ stress field for the actual underground cavern at the Huangdeng hydropower station. The two-stage optimization algorithm produces a more realistic estimate of the stress distribution within the investigated area. Thus, this technique may have practical applications in realistic scenarios requiring efficient and accurate estimations of the in situ stress in a rock-mass. 相似文献
7.
The coal tar was qualitative and quantitative anMyzed by gas chromatography （GC） method. 74 components were identified exactly by gas chromatographY-mass spectrometry （GC-MS）. 31 components （37%） were quantitatively analyzed by gas chromatography-flame ionization detector （GC-FID）. The linearity, accuracy, precision, limit of detection （LOD） and limit of quantitative （LOQ） determination were inspected. The scope of quantitative analysis by CC was discussed. The experimental results of thermogravimetric analysis （TGA） proved that GC quantitative analysis of the coal tar was reliable. 相似文献
8.
9.
A series of polysulfonamide （PSA）/TiO 2 modifier nano-composite films were successfully prepared by in-situ polymerization at a low temperature based on 4, 4-diaminodiphenylsulfone and terephthaloyl chloride in the common solvent N, N-dimethylacetamide （DMAc）. It was shown that the nano particles were well dispersed in the polymer substrate. Mean-while, PSA/TiO 2 /modifier composites exhibited good UV-resistant properties and mechanical properties. In addition, the composites’ heat stability improved. These prepared composites are promising in preparing spinning solution and might have potential application in heat-resistant fiber. 相似文献
10.
This paper presents a rheology-based approach to animate realistic face model. The dynamic and biorheological
characteristics of the force member (muscles) and stressed member (face) are considered. The stressed face can be modeled
as viscoelastic bodies with the Hooke bodies and Newton bodies connected in a composite series-parallel manner. Then, the
stress-strain relationship is derived, and the constitutive equations established. Using these constitutive equations, the face
model can be animated with the force generated by muscles. Experimental results show that this method can realistically
simulate the mechanical properties and motion characteristics of human face, and performance of this method is satisfactory. 相似文献
characteristics of the force member (muscles) and stressed member (face) are considered. The stressed face can be modeled
as viscoelastic bodies with the Hooke bodies and Newton bodies connected in a composite series-parallel manner. Then, the
stress-strain relationship is derived, and the constitutive equations established. Using these constitutive equations, the face
model can be animated with the force generated by muscles. Experimental results show that this method can realistically
simulate the mechanical properties and motion characteristics of human face, and performance of this method is satisfactory. 相似文献
11.
WANG Yongji WANG Hong Department of Control Science & Engineering Huazhong University of Science &Technology Wuhan Hubei P.R.China Control Systems Centre UMIST PO Box Manchester M QD UK 《重庆大学学报(英文版)》2004,3(1):26-29
~~identificationis7-7-1,where3nm==,andtheRPEalgorithmisusedtoupdatetheweightingofPNN.Thewholetrainingprocessuses800iterations.InordertoovercometheinaccuracyofPNNmodel,thecontrollerstructureisacompositeoneasfbff()()()ututut=+,(37)wherefb()utistheoutputoffeedbackcontroller,ff()utistheoutputofpredictivecontrollerdescribedbyEq.(14),with0.20=,0.40=,andmax5K=.Insimulatedclosedloopcontrol,ufb(t)isaproportionalcontroller,fb()()Putket=and5.0Pk=.Theset-pointofthesystemisd0.15,if040,and120()0.24,if4… 相似文献
12.
Instead of manual polishing work for aluminum wheel hub （hub） surface, a new planetary scroll surface polishing method based on the rotation and revolution of hub in abrasives is presented in this paper. Since conventional barrel rotation polishing mode is unsatisfactory, shorter polishing period and lower energy consumption are expected. The surface polishing mechanism of the proposed method is ghen introduced. The influence of cutting velocity, cutting angle, abrasive on surface polishing quality and efficiency, as well as the correlation of the revolution velocity and the rotation velocity of hub are discussed. Experimental results show that high surface polishing quality and efficiency can be achieved with the new polishing method implying that a dustless clean working environment is realized. 相似文献
13.
In this paper, a 10 GHz radio over fiber system is analyzed. The Brillouin fiber-optic ring laser is used in the
center station (CS) to suppress the optical carrier for the modulation depth enhancement. Simultaneously, the Stockes wave
induced by the Brillouin amplification injects and locks the Fabry-Perot (FP) laser to output a signal-mode optical source,
which works as the uplink optical carrier. 相似文献
center station (CS) to suppress the optical carrier for the modulation depth enhancement. Simultaneously, the Stockes wave
induced by the Brillouin amplification injects and locks the Fabry-Perot (FP) laser to output a signal-mode optical source,
which works as the uplink optical carrier. 相似文献
14.
INTRODUCTION Creep is an internal characteristic of concrete under long-term load. A long time has elapsed since the first discovery of concrete creep in 1907 by Hatt. Many researches have been devoted to this complex problem ever since. However, despite major suc-cesses, the creep phenomenon is still far from being fully understood, even though the phenomenon has occupied some of the best minds in the field, such as Glanville, Dischinger, Troxell, Pickett, Neville, etc. Creep phenome… 相似文献
15.
According to the principles of simultaneous equilibrium and electronic charge neutrality, the thermodynamics of Zn（II）-NaOH-H2O system was studied in this paper. Varying the concentration of sodium hydroxide, in range of 0- 400 g/L, the distribution law of all zinc species and the mathematical model of equilibrium concentration of zinc in the system were obtained. The relative errors between theoretic calculation and the experimental values of total concentration of zinc were analyzed, and the absolute average error is only 0.129 8%. The mathematical model and the thermodynamic data are believable. 相似文献
16.
Internal exposure of university students to polycyclic aromatic hydrocarbons(PAHs)was assessed through urinary PAHs metabolites. Eight monohydroxylated PAHs(OH-PAHs)were detected with high performance liquid chromatography (HPLC). The detectable frequencies were 59%-100% for different analytes. Major components in the subjects‘ urine were 2-hydroxynaphthalene(2-OHNap, 0.60 μg/mmol creatinine), followed by hydroxyphenanthrene(ΣOH-Phe, 0.38 μg/mmol cre-atinine)and 2-hydroxyfluorene(2-OHFlu, 0.25 μg/mmol creatinine). Excretion of 1-hydroxypyrene(1-OHPyr, 0.08 μg/mmol creatinine)was almost one order of magnitude lower than the 2-OHNap level in the urine samples. Phenanthrene can be metabolized to five monohydroxy metabolites in human urine. In the present study, 1-or 9-hydroxyphenanthrene(1-or9-OHPhe)was the dominant component(79%), followed by 2-+3-OHPhe(18%)and 4-OHPhe(3%). The study indicates that 1-OHPyr may not be a good marker for total PAHs exposure, and monitoring of 2-OHNap, 2-OHFlu, 1-or 9-OHPhe and 1-OHPyr as multiple biomarkers are more suitable than only using 1-OHPyr. The levels of OH-PAHs detected in urines of students living in Shanghai are higher those of people in other countries or regions. The concentrations of urine OH-PAHs are directly related to the exposure to PAHs in the environment, indicating that Shanghai residents are at high health risk. 相似文献
17.
This paper presents a novel low-pass filter （LPF） with sharp rejection, wide stopband and compact size, which are realized by the defected ground structure （DGS） and the defected microstrip structure （DMS）. The equivalent circuit model is proposed and the circuit parameters are extracted by the circuit simulation software. The parameters measured are 3 dB cutoff frequency fc of 5.2 GHz, the insertion loss less than 0.5 dB from DC to 4.0 GHz and S21 less than -20 dB within the wide stopband from 6 GHz to 16 GHz. The results of the circuit optimization agree well with those of the full wave simulation and the measured ones, which validate the effectiveness of the equivalent circuit model. The size of the proposed LPF is decreased compared with normal LPF. This LPF can be applied in rectennas to eliminate high order harmonics. 相似文献
18.
基于离散单元法建立了圆柱形颗粒阻尼器的仿真模型,研究了阻尼器内颗粒在不同激振条件下的运动形态及其能量耗散大小。为了获取两者之间的定量关系,应用基于网格搜索法(GS)的支持向量机(SVM)建立了颗粒运动形态的分类预测模型及其能量损耗的回归预测模型,对颗粒运动形态的分布及其能量损耗的大小进行了预测,并通过仿真进行了验证。结果表明:基于GS方法优化的SVM能够建立一个预测准确度很高、推广泛化能力很强的分类和回归预测模型,该预测模型不仅能够很好地揭示颗粒系统在不同运动形态下的能量耗散的变化规律,而且还能在较大的激振条件范围内确定系统能量耗散最大值及对应的运动形态。 相似文献
19.
A Second-Order Conditionally Linear Mixed Effects Model With Observed and Latent Variable Covariates
Jeffrey R. Harring Nidhi Kohli Rebecca D. Silverman Deborah L. Speece 《Structural equation modeling》2013,20(1):118-136
A conditionally linear mixed effects model is an appropriate framework for investigating nonlinear change in a continuous latent variable that is repeatedly measured over time. The efficacy of the model is that it allows parameters that enter the specified nonlinear time-response function to be stochastic, whereas those parameters that enter in a nonlinear manner are common to all subjects. In this article we describe how a variant of the Michaelis–Menten (M–M) function can be fit within this modeling framework using Mplus 6.0. We demonstrate how observed and latent covariates can be incorporated to help explain individual differences in growth characteristics. Features of the model including an explication of key analytic decision points are illustrated using longitudinal reading data. To aid in making this class of models accessible, annotated Mplus code is provided. 相似文献
20.
A novel model of fuzzy clustering using kernel methods is proposed. This model is called kernel modified possibilisticc-means (KMPCM) model. The proposed model is an extension of the modified possibilistic c-means (MPCM) algorithm byusing kernel methods. Different from MPCM and fuzzy c-means (FCM) model which are based on Euclidean distance, theproposed model is based on kernel-induced distance. Furthermore, with kernel methods the input data can be mappedimplicitly into a high-dimensional feature space where the nonlinear pattern now appears linear. It is unnecessary to docalculation in the high-dimensional feature space because the kernel function can do it. Numerical experiments show thatKMPCM outperforms FCM and MPCM. 相似文献