Improved computation of the standard error in the regression coefficient estimates of a multivariate calibration model

A multivariate calibration model consists of regression coefficient estimates whose significance depends on the associated standard errors. A recently introduced leave-one-out (LOO) method for computing these standard errors is modified to achieve consistency with the jack-knife method. The proposed modification amounts to multiplying the LOO standard errors with the factor (n - 1)/n1/2, where n denotes the number of calibration samples. The potential improvement for realistic values of n is illustrated using a practical example.     

基于光谱反射率确定 Y_N 模型公式因数n及有效网点面积率的方法研究

目的基于Y_N模型的打印机正向特征化,考虑到物理网点扩大与光学网点扩大对模型的影响,需要通过单通道墨量限制,以及采用非线性最优化的方法,来确定油墨的有效网点百分比和该模型修正系数n。方法使用ProductionHouse 10.2软件实现单通道的墨量限制,使用非线性最优化的方法计算获得Y_N模型的公式因子n为2.5。结果将此n值带入Y_N模型的反向变换形式,可以获得修正后的有效网点面积率,并获得有效网点百分比与理论网点百分比的一维查找表,进而拟合了理论网点百分比与有效网点百分比,获得网点百分比的传递函数。结论通过单通道墨量限制和引入Y_N模型公式因数n,消除了因物理网点扩大和光学网点扩大对Y_N模型造成的影响,并准确拟合了有效网点百分比与理论网点百分比的传递函数。     

弹体磁屏蔽效能的计算与仿真

根据弹体形状的特点,引入近似法计算其横截面和纵向截面的磁屏蔽效能,并用有限元软件ANSYS进行了仿真验证.结果表明符合程度较好,在钢质弹体材料相对磁导率取其最大值时,弹体对地磁场的屏蔽系数可达99%以上.该结果为地磁探测硬件电路设计和姿态角算法设计提供了重要参考.     

芯棒对铝合金矩形管绕弯回弹作用的数值模拟

为掌握芯棒参数对薄壁矩形管绕弯成形回弹的影响规律,从而为芯棒参数的选取与设计提供依据,基于ABAQUS有限元软件建立了3A21铝合金薄壁矩形管弯曲成形及回弹三维有限元模型,试验验证了所建模型的可靠性.基于所建模型,研究了芯棒参数如芯棒/芯头与管坯摩擦(μm)、芯棒/芯头与管坯间隙(δm)、芯头个数(n)及芯棒伸出量(em)对回弹角的影响.结果表明:抽芯是一个应力预卸载过程,可显著减小回弹;随着芯棒/芯头与管坯摩擦系数(μm)的增加,回弹减小;随着芯棒/芯头与管坯间隙(δm)的增加,回弹增加;随着芯头个数(n)的增加,回弹减小;随着芯棒伸出量(em)的增加,回弹先增大后减小.     

Effects of pressure sensitivity on the η factor and the J integral estimation for compact tension specimens

In this paper, the effects of pressure-sensitive yielding on the factor and the J integral estimation for compact tension specimens are investigated. The analytical expressions for and J for pressure-insensitive von Mises materials are generalized to pressure-sensitive Drucker-Prager materials using a lower bound approach. The factor as a function of the pressure sensitivity and the normalized crack depth for compact tension specimens is derived under plane stress and plane strain conditions. The numerical results indicate that the factor decreases as the pressure sensitivity increases. The effects are more pronounced under plane strain conditions than under plane stress conditions. However, the effects of the pressure sensitivity on are found to be mild in general. For rigid perfectly-plastic materials, the J estimation for pressure-sensitive materials is also reduced to a simple expression of the tensile yield stress times the crack tip opening displacement as for the von Mises materials.     

Discussion on the improvement of opto-RF link properties by using a bipolar cascade laser source

This paper studies the possible improvement in RF link properties that can stem from electrically cascading several laser sources and combining the light from each source into a single information-carrying light beam. The effect of carrier recycling is first studied within a discrete architecture consisting of n individual laser diodes macroscopically connected in series. An RF link gain improvement proportional to n², and a link noise figure improvement proportional to n is found. The model is validated by experimental data. The architecture nonetheless carries some drawbacks, including the need for a zero-loss optical combining device to benefit from the RF link gain improvement, and some bandwidth shortcomings. The effect of carrier recycling within an integrated laser device, a so-called bipolar cascade laser, is then studied. In order to push back the limitations of the discrete architecture, the device consists of n active regions integrated into a single laser cavity. A rate equation model is applied to this promising structure and it is found that, in good agreement with previously published results, the external efficiency is expected to increase by a factor of n, leading to a possible RF link gain improvement by a factor of n². However, because the laser noise is dominated by the photon corpuscular noise, a weak influence of electrically cascading active junctions into a single laser cavity on the laser intensity noise, and thus on the link noise figure, is expected     

A study of neutron radiation quality with a tissue-equivalent proportional counter for a low-energy accelerator-based in vivo neutron activation facility

The accelerator-based in vivo neutron activation facility at McMaster University has been used successfully for the measurement of several minor and trace elements in human hand bones due to their importance to health. Most of these in vivo measurements have been conducted at a proton beam energy (E(p)) of 2.00 MeV to optimise the activation of the selected element of interest with an effective dose of the same order as that received in chest X rays. However, measurement of other elements at the same facility requires beam energies other than 2.00 MeV. The range of energy of neutrons produced at these proton beam energies comes under the region where tissue-equivalent proportional counters (TEPCs) are known to experience difficulty in assessing the quality factor and dose equivalent. In this study, the response of TEPCs was investigated to determine the quality factor of neutron fields generated via the (7)Li(p, n)(7)Be reaction as a function of E(p) in the range 1.884-2.56 MeV at the position of hand irradiation in the facility. An interesting trend has been observed in the quality factor based on ICRP 60, Q(ICRP60), such that the maximum value was observed at E(p)=1.884 MeV (E(n)=33±16 keV) and then continued to decline with increasing E(p) until achieving a minimum value at E(p)=2.0 MeV despite a continuous increase in the mean neutron energy with E(p). This observation is contrary to what has been observed with direct fast neutrons where the quality factor was found to increase continuously with an increase in E(p) (i.e. increasing E(n)). The series of measurements conducted with thermal and fast neutron fields demonstrate that the (14)N(n, p)(14)C produced 580 keV protons in the detector play an important role in the response of the counter under 2.0 MeV proton energy (E(n) ≤ 250 keV). In contrast to the lower response of TEPCs to low-energy neutrons, the quality factor is overestimated in the range 1-2 depending on beam energy <2.0 MeV. This study provides an insight to understanding the response of TEPCs in low-energy neutron fields where the neutrons are moderated using a polyethylene moderator.     

中国城市要素利用质量水平测算与研究:基于要素市场扭曲视角

基于2000-2016年期间中国30个地区260个地级及以上城市的平衡面板数据,将要素市场扭曲划分为资本要素市场扭曲和劳动要素市场扭曲两个部分,采用超越对数生产函数测算中国城市资本要素市场扭曲和劳动力要素市场扭曲水平并进行研究,在此基础上进一步分析城市生产要素扭曲水平与城市规模之间的关系。研究结果发现:2000-2016年期间,中国城市总体的资本要素市场和劳动力要素市场均处于较为严重的扭曲状态,两种要素市场上均出现了负向扭曲,且资本要素市场扭曲比劳动力要素市场扭曲程度更为严重,即城市资本—劳动相对扭曲指数显著大于1;中国260个城市的资本要素市场均出现负向扭曲,劳动力要素市场出现正向扭曲和负向扭曲的城市分别占据全部样本城市的38.5%和61.5%;中国城市要素市场扭曲水平与城市规模均呈现倒“U”型关系,当城市人口规模分别超过475.80万人和379.18万人时,城市人口规模对资本要素市场扭曲和劳动力要素市场扭曲的影响由正向变为负向。     

Diffraction-based solid immersion lens

A solid immersion lens based on diffraction (dSIL) is proposed as an alternative to the conventional design based on refraction. A design analogous to a Fresnel zone plate is derived in accordance with the Huygens-Fresnel principle. Fabrication of a binary dSIL is achieved by electron-beam lithography and reactive-ion etching on LaSF35, with index n = 2.014. Measurement of the point-spread function is performed with near-field optical microscopy. The results are in accord with the expected resolution enhancement of a factor n with respect to the diffraction limit.     

Optimization of a rhomb-type quarter-wave phase retarder

Apreviously reported two-reflection, undeviating-beam total internal reflection (TIR) quarter-wave phase retarder is optimized. The specifications and characteristics of the device are sensitive to the refractive index n of the rhomb material. In particular, the size of the rhomb can be reduced by a factor of 11 for the same aperture size if a glass with n = 1.70 is used instead of one with n = 1.53. Optimal conditions are in the refractive-index interval n = 1.68-1.71. Coated rhombs of this type are mentioned.     

Dynamic stress intensity factor of a functionally graded material under antiplane shear loading

Summary The dynamic response of a finite crack in an unbounded Functionally Graded Material (FGM) subjected to an antiplane shear loading is studied in this paper. The variation of the shear modulus of the functionally graded material is modeled by a quadratic increase along the direction perpendicular to the crack surface. The dynamic stress intensity factor is extracted from the asymptotic expansion of the stresses around the crack tip in the Laplace transform plane and obtained in the time domain by a numerical Laplace inversion technique. The influence of graded material property on the dynamic intensity factor is investigated. It is observed that the magnitude of dynamic stress intensity factor for a finite crack in such a functionally graded material is less than in the homogeneous material with a property identical to that of the FGM crack plane.     

非等温DSC研究超支化聚醚/PEG/IPDI体系的固化反应动力学

采用非等温差示扫描量热法(DSC)研究了超支化聚醚对聚乙二醇/异佛尔酮二异氰酸酯体系(PEG/IPDI)固化反应动力学的影响。结果表明,PEG/IPDI体系的固化反应表观活化能约为53.278 kJ/mol,反应级数为0.914,指前因子为1.500×105min-1;加入6%的超支化聚醚后,体系的固化峰温升高,表观活化能、反应级数和指前因子分别提高至87.577 kJ/mol、0.960、1.201×1010min-1,机理函数仍遵循Avrami-Erofeev方程G(α)=[-ln(1-α)]n,只是方程中的指数n有所变化。超支化聚醚对PEG/IPDI体系的固化反应有一定的延缓作用,但不改变固化机理。浅析了超支化聚醚影响PEG/IPDI体系固化的原因。     

A unified drain current model for nanoscale double-gate and surrounding-gate MOSFETs incorporating velocity saturation

A unified drain current model for undoped or lightly doped symmetric double-gate and surrounding-gate MOSFETs incorporating velocity saturation effect is proposed in this paper. The unified charge-based core model for undoped or lightly doped double-gate and surrounding-gate MOSFETs is presented first based on the previously published separate models. Caughey-Thomas engineering mobility model with its exponent factor n = 2 is then integrated self-consistently into the unified drain current model development of the two device structures. Extensive two dimensional and three dimensional device simulations are performed to validate the proposed model. Good agreements of the output and transfer characteristics between the unified model and the numerical simulations are obtained for both the double-gate and surrounding-gate MOSFETs. Symmetry property of the proposed unified current model is obtained with the exponent factor n = 2 in Cauhey-Thomas Model.     

Stress-dependent thermal relaxation effects in micro-mechanical resonators

Thermal relaxation is a key factor in determining the quality factor of micro and nano resonators, which controls the energy dissipation through the coupling of the mechanical and thermal domains. While the literature contains approximate, exact and computational models for quantitative analysis of thermo-elastic coupling, very few techniques are available to ‘tune’ it without changing the material, geometry or operating conditions. In this paper, we develop an analytical model that considers a pre-stress in a flexural resonator to modify the thermal relaxation time and thus increase the quality factor. The effects of length-scale, pre-stress and geometry on the quality factor have been analyzed. The model predicts that significant improvement in terms of dimensionless quality factors is possible by tuning the pre-stress.     

非规则梁桥的振型重要性指标研究

针对非规则梁桥的振型重要性指标进行研究。首先,通过理论分析,确定在判断振型重要性方面,传统的振型质量参与系数存在缺点,并定义了振型位移贡献、振型位移贡献系数、振型位移贡献比例等新指标。然后,针对一座典型的非规则梁桥,通过振型质量参与系数分析和振型位移贡献系数分析的对比研究,确定采用振型位移贡献比例判断振型重要性,更加合理。最后,通过多座桥梁的参数分析,验证了振型位移贡献比例比质量参与系数更加优越。研究结果表明：振型质量参与系数仅能反映振型对于结构总体动力反应的重要性,而不能明确反映振型对于结构局部动力反应的重要性;振型位移贡献比例能弥补这一缺陷,可以作为振型重要性的指标;当前n阶振型位移贡献比例之和超过80%时,以前n阶振型为基础得到的结构位移可以满足非规则梁桥计算精度的需要。     

幂律型非牛顿流体本构常数的测量精度问题

研究了幂律型非牛顿流体本构常数的测量误差对于计算广义雷诺数、阻力系数以及建立二者实验关系的影响；指出在一定的（ｎ，ｋ）范围内，误差传播系数相当大，以致对本构测量精度要求很高。还分析了传播系数的因次和谐问题，并提出了改进本构测量的建议。     

Method of measuring Bacillus anthracis spores in the presence of copious amounts of Bacillus thuringiensis and Bacillus cereus

A sensitive and reliable method for the detection of Bacillus anthracis (BA; Sterne strain 7702) spores in presence of large amounts of Bacillus thuringiensis (BT) and Bacillus cereus (BC) is presented based on a novel PZT-anchored piezoelectric excited millimeter-sized cantilever (PAPEMC) sensor with a sensing area of 1.5 mm2. Antibody (anti-BA) specific to BA spores was immobilized on the sensing area and exposed to various samples of BA, BT, and BC containing the same concentration of BA at 333 spores/mL, and the concentration of BT + BC was varied in concentration ratios of (BA:BT + BC) 0:1, 1:0, 1:1, 1:10, 1:100, and 1:1000. In each case, the sensor responded with an exponential decrease in resonant frequency and the steady-state frequency changes reached were 14 +/- 31 (n = 11), 2742 +/- 38 (n = 3), 3053 +/- 19 (n = 2), 2777 +/- 26 (n = 2), 2953 +/- 24 (n = 2), and 3105 +/- 27 (n = 2) Hz, respectively, in 0, 27, 45, 63, 154, and 219 min. The bound BA spores were released in each experiment, and the sensor response was nearly identical to the frequency change during attachment. These results suggest that the transport of BA spores to the antibody immobilized surface was hindered by the presence of other Bacillus species. The observed binding rate constant, based on the Langmuir kinetic model, was determined to be 0.15 min-1. A hindrance factor (alpha) is defined to describe the reduced attachment rate in the presence of BT + BC and found to increase exponentially with BT and BC concentration. The hindrance factor increased from 3.52 at 333 BT + BC spores/mL to 11.04 at 3.33 x 105 BT + BC spores/mL, suggesting that alpha is a strong function of BT and BC concentration. The significance of these results is that anti-BA functionalized PEMC sensors are highly selective to Bacillus anthracis spores and the presence of other Bacillus species, in large amounts, does not prevent binding but impedes BA transport to the sensor.     

Evaluation of Schottky barrier diodes fabricated directly on processed 4H-SiC(0001) surfaces

Silicon carbide (SiC) is a suitable substrate for low-power-consumption power devices and high-temperature applications. However, this material is difficult to machine because of its hardness and chemical inertness, and many machining methods have been studied intensively in recent years. In this paper, we present a simple method to evaluate the electrical properties of the processed surface using the ideal factor n of a Schottky barrier diode (SBD) fabricated directly on the processed surface. Upon comparing the values of n for SBDs fabricated on a damaged SiC surface and a non-damaged SiC surface, we found that there is a significant difference in the dispersion and magnitude of n. Furthermore, by combining this technique with slope etching, we were able to estimate the thickness of the damaged sub-surface layer.     

Experimental investigations of ice slurry flows in horizontal pipe based on monopropylene glycol

In this paper, the pressure drop behavior of ice slurry based on MPG-water in a circular horizontal tube is experimentally investigated. The secondary fluid was prepared by mixing MPG and water to obtain initial MPG concentration varying from 5% to 24%. The pressure drop tests were conducted to cover laminar flow with ice mass fraction varying from 5% to 25% depending on test conditions. Results from test reveal that the ice slurry behaves as non-Newtonian: thickening flow (n > 1) or shear thinning flow (n < 1) and sometimes as Newtonian flow (n ≈ 1). The moving bed is observed in particular flow conditions.The experimental results for viscosities were compared to the analytical results. In addition, experimental results of the Darcy friction factor were compared to Poiseuille model who gives good agreement with experimental results.Furthermore, for transport purposes, it has been shown that 11% initial MPG concentration gives the best results.     

Promising thermoelectric properties of commercial PEDOT:PSS materials and their bi2Te3 powder composites

Newly commercialized PEDOT:PSS products CLEVIOS PH1000 and FE-T, among the most conducting of polymers, show unexpectedly higher Seebeck coefficients than older CLEVIOS P products that were studied by other groups in the past, leading to promising thermoelectric (TE) power factors around 47 μW/m K(2) and 30 μW/m K(2) respectively. By incorporating both n and p type Bi(2)Te(3) ball milled powders into these PEDOT:PSS products, power factor enhancements for both p and n polymer composite materials are achieved. The contact resistance between Bi(2)Te(3) and PEDOT is identified as the limiting factor for further TE property improvement. These composites can be used for all-solution-processed TE devices on flexible substrates as a new fabrication option.