近红外光谱分析中建模光谱宽度的选择

为选择生化样品近红外光谱分析中最优的建模光谱宽度,结合样品特征波长与光谱学原理开展研究.收集348份血清样品,以血清中胆固醇、甘油三酯为例进行分析.根据光谱学原理及2 mm厚度血清的光谱吸光度,选择一级倍频区域作为分析波段,考察该区域内不同宽度光谱范围的模型效果.优选出胆固醇与甘油三酯的最优光谱宽度分别为70 nm和1...     

Efficient planar organic solar cells with the high near-infrared response

Efficient planar organic solar cells extending the response into the near-infrared (NIR) were fabricated using the highly ordered Titanyl phthalocyanines (TiOPc) films as the donor layer. This type of films obtained through the weak epitaxy growth (WEG) method presents good continuity and integrity with the low density of grain boundaries. More importantly the films own a strong absorption in the NIR (750–950 nm) and a broad absorption spectrum from 550 to 950 nm. Meanwhile the high external quantum efficiency (EQE) is obtained in the NIR with the peak value over 38% and the EQE is over 18% in the entire response range, which could benefit from the long exciton diffusion length and the high carrier mobility of the highly ordered films. Thereby the fabricated planar solar cells achieve a high short-circuit current density (J_sc) of 9.26 mA cm^?2 and a power conversion efficiency (PCE) of 2.67%.     

近红外光谱比值法测定烟草中六组分含量

以300个烟草样品的近红外光谱为基础,采用比值法和多元二次回归相结合的方法,建立了近红外光谱与烟草六组分(尼古丁、总糖、还原糖、总氮、钾、氯)含量间的一种测量模型,并采用交叉验证和样品实际测量的方法对模型的预测能力进行测试,结果表明该模型具有良好的预测能力,是一种快速高效检测烟草品质的方法,且具有测定波长少、计算简单、实现方便等特点,易于推广和产品化。     

复方樟柳碱联合氪激光早期治疗缺血型视网膜中央静脉阻塞的血流动力学改变

目的:探讨复方樟柳碱联合氪激光早期治疗缺血型视网膜中央静脉阻塞(CRVO)患者血液动力学参数和中心视力的影响。方法:缺血型CRVO患者57例(57眼),随机分为治疗组29例(29眼)和对照组28例(28眼),所有患者均使用PRP治疗,治疗组另加用复方樟柳碱患眼侧颞浅动脉旁注射,14天一个疗程,连续2个疗程,治疗前后通过彩色多普勒超声检测视网膜中央动脉(CRA)的收缩期峰值血流速度(peak systolic velocity,PSV)、舒张末期血流速度(end diastolic velocity,EDV)和阻力指数(resistance index,RI)及视网膜中央静脉(CRV)的最大流速(Vmax)和最小流速(Vmin),并通过比较治疗前后视力恢复的有效率来判断疗效。结果:两组在治疗后,CRA的PSV和EDV都能有效提高(P0.05),而RI仅在复方樟柳碱治疗组有显著改善(P0.05),复方樟柳碱治疗组可以明显改善CRV的Vmax和Vmin(P0.05),对照组在CRV的本次研究涉及的动力学参数没有影响;复方樟柳碱治疗组在治疗后视力改善有效率达96.55%,对照组为86.71%。结论:复方樟柳碱治疗组能有效改善缺血型视网膜中央静脉阻塞的血流动力学,在改善中心视力上也具有优势。     

Mathematical model of the phase-locked loop with a current detector

The mathematical model of the pulses phase-locked loop (PLL) with a frequency-phase detector and a current pump, which is represented as a set of difference and transcendental equations and relies on the dynamics of the given deterministic system (in the general case, an arbitrary-order loop filter) described by an automation with a finite number of components and combined differential equations, is examined. An algorithm describing the operation of the in-lock indicator of the given PLL is proposed. The particular cases of the first- and second-order loop filters are discussed. PLL simulation is performed under transient conditions.     

A model for post-occlusive reactive hyperemia as measured with laser-Doppler perfusion monitoring

To facilitate the quantitative analysis of post-occlusive reactive hyperaemia (PORH), measured with laser-Doppler perfusion monitoring (LDPM) on extremities, we present a flow model for the dynamics of the perfusion of the tissue during PORH, based on three parameters: two time constants (tau1 and tau2) and the ratio of the maximum flux and the resting flux. With these three constants quantitative comparisons between experiments will be possible and, therefore, we propose to adopt this approach as future standard. For this reason, we also developed a computer program to perform the fit of the model to measured data.     

Employing a ground model to accurately characterize electronic devices measured with GSG probes

Traditionally, when measuring an electronic device, the nonideal (non-50 /spl Omega/) electrical behavior of the ground-signal-ground probes is removed through calibration. However, this procedure does not allow for an accurate measurement of devices that exhibit an unbalanced flow of electrical currents through the two ground fingers of the probe. We found that a simple interface circuit can be used by a circuit simulator, such as ADS, to reproduce the measurements of devices in which unbalanced ground currents flow in the return paths. A simple experimental method to determine the interface circuit is given.     

Unsupervised robust nonparametric estimation of the hemodynamic response function for any fMRI experiment

This paper deals with the estimation of the blood oxygen level-dependent response to a stimulus, as measured in functional magnetic resonance imaging (fMRI) data. A precise estimation is essential for a better understanding of cerebral activations. The most recent works have used a nonparametric framework for this estimation, considering each brain region as a system characterized by its impulse response, the so-called hemodynamic response function (HRF). However, the use of these techniques has remained limited since they are not well-adapted to real fMRI data. Here, we develop a threefold extension to previous works. We consider asynchronous event-related paradigms, account for different trial types and integrate several fMRI sessions into the estimation. These generalizations are simultaneously addressed through a badly conditioned observation model. Bayesian formalism is used to model temporal prior information of the underlying physiological process of the brain hemodynamic response. By this way, the HRF estimate results from a tradeoff between information brought by the data and by our prior knowledge. This tradeoff is modeled with hyperparameters that are set to the maximum-likelihood estimate using an expectation conditional maximization algorithm. The proposed unsupervised approach is validated on both synthetic and real fMRI data, the latter originating from a speech perception experiment.     

Mathematical model with minimum number of independent coefficients for transistors for high frequencies

A stepwise procedure is described to select the independent coefficients when forming a mathematical model of transistors for high frequencies. The basic idea is to determine the least-squares estimates of the coefficients from the measured scattering parameters S in a group of transistors of the same type. Examination of the correlation matrix of these estimates enables one to accept, in turn, the independent coefficient that has no linear relationship with the preceding ones already selected as independent.     

A mathematical model for the assessment of hemodynamic parametersusing quantitative contrast echocardiography

A mathematical model for the assessment of hemodynamic parameters using quantitative echocardiography is presented. The method involves the intravenous injection of an ultrasonic echo contrast agent. The relative enhancement of the backscattered ultrasound intensity is measured as a function of time (the time-intensity curve). From this measurement, the volume flow rate (cardiac output) and the mixing volume are calculated. Relevant acoustic properties of the ultrasound contrast agent are discussed. An in vitro experiment is performed to corroborate the theory presented     

用Klippel系统对扬声器频响近场测试的分析

近年出现了一款室内条件下测试扬声器特性的Klippel系统,在普通房间里近场测试频响特性.借助一只普通的圆形扬声器,从理论基础和实际测试两个方面对扬声器进行分析对比,检验了该测试设备获得频响测试结果的可信性,并以此为基础,为选择扬声器的适用频段提供技术支持.     

Mathematical analysis of the multi-server queueing model for dynamic channel reservation in wireless networks

We consider a multi-server queueing model with two types of customers offered in Y. C. Kim et al. (1999) for modeling dynamic channel reservation based on mobility in wireless networks. Mathematical analysis given contains essential errors what makes some results negligible. We provide a correct analysis of the model     

任意形状孔径的干涉图像波面拟合的数学矢量模型

文中利用移相干涉术的特点提出了自动检测任意形状孔径中有干涉条纹区域的方法,测试中,当测试波前相对于参考滤前的光程差是照明波长的整数倍时形成干涉条纹,它此而形成的二维图就是干涉图像。干涉术是一种从干涉图像提取测试波面信息的光学测试技术,它包括对干涉图像的采样、条纹定级次和波面拟合三步。这里提出了一个对干涉图像拟合处理的线性代数矢量模型,应用线性代数矢量矩阵的知识详细地推导出了一种对干涉图像的处理带有一般性的矢量拟合公式,由最小二乘法逼近多项式拟合的相位值数据,用Ｇｒａｎ－Ｓｃｈｍｉｄｔ算法正交化处理多项式组,用反向替代法技术来求解最初多项式组的权因子系数。     

On the use of multivariable piecewise-linear models for predicting human response to anesthesia

The standard modeling paradigm used to describe the relationship between input anesthetic agents and output patient endpoint variables are single-input single-output pharmacokinetic-pharmacodynamic (PK-PD) compartment models. In this paper, we propose the use of multivariable piecewise-linear models to describe the relations between inputs that include anesthesia, surgical stimuli and disturbances to a variety of patient output variables. Subspace identification methods are applied to clinical data to construct the models. A comparison of predicted and measured responses is completed, which includes predictions from PK-PD models, and piecewise-linear time-invariant models.     

Approach to model order reduction for angular response calculationsin periodic structures

A framework for implementing model order techniques for periodic structure analysis is presented. Appropriate choice of the problem formulation, in combination with straightforward Pade approximations, permit the entire angular response to be extrapolated from the solution at a single aspect angle     

MATHEMATICAL MODEL FOR ACCESS MODE OF CONTENTION－COLLISION CANCELLATION IN A STAR LAN

I type system model of CCCAM(Contention-Collision Cancellation Access Mode) is studied through mathematical modelling and simulation.There are two innovations:(1) in the process of mathematical modelling,the instance of ^4serving customers unsuccessfully‘ is taken into account;(2) the time at which customers depart after having been served successfully are chosen to be the embedded point,thereby “free period” is introduced reasonably.So the mathematical modelling and analysis result in this paper are significant for application of wire star LAN and wireless star LAN.     

Physiologic signal acquisition and processing for human hemodynamic research in a clinical cardiac-catheterization laboratory

This paper describes state-of-art-technology in transducer design, signal acquisition, and digital processing of physiologic signals obtained from human patients during clinical cardiac catheterization. Custom-designed multisensor catheters provide multiple simultaneous high-fidelity pressure and flow-velocity signals from the right and left heart in man at rest and during a variety of physiologic and pharmacologic stresses. After processing by an analog system designed with special features for clinical cardiologists and cardiac-catheterization technicians, a dedicated minicomputer enters these signals into a variety of programs designed for human hemodynamic research. The overall capabilities of this system are unique in clinical cardiology and represent a valuable application of the principals of signal acquisition and processing to biologic systems.