工作家庭价值观匹配与工作家庭冲突关系研究

在个人-环境匹配理论的基础上,采用工作家庭冲突和个体与组织工作家庭价值观量表对来自不同企业的203名员工进行测量,使用结构方程模型方法验证了个体和组织工作家庭价值观的匹配与工作家庭冲突之间的关系。结果显示,匹配与两个方向的工作家庭冲突都负相关。并在此基础上提出了人力资源管理的建议。     

Fourier-transformation, phase-iteration, and least-square-fit image processing for Young's fringe pattern

The fast Fourier transform, phase iteration, and the least-square fit are combined into an automated processing technique for the analysis of Young's fringe patterns. A Young's fringe pattern is first fast-Fourier-transform filtered to get an initial phase, phase iteration is carried out to improve the phase if necessary, and then the phase is least-square fitted to a phase plane. The magnitude and the direction of the displacement associated with the Young's pattern are determined from the phase plane.     

性别、人格与脑力绩效

本研究目的在于考察性别、人格与若干种基本脑力绩效的关系.共124名(68男,56女)大学本科生参加了实验.使用A型行为问卷和艾森克人格问卷来度量人格;使用6项脑力任务:短时记忆、简单计算、逻辑推理、空间处理、简单反应时和警戒任务来进行实验并考核每个被试的任务绩效,每项任务持续时间约为10～20min.结果表明:男性被试的逻辑推理任务绩效高于女性被试,而女性被试的警戒任务绩效高于男性被试;A型人格被试的逻辑推理和警戒任务绩效高于B型人格被试,而B型人格被试的空间处理任务绩效高于A型人格被试;在艾森克人格的4个维度上,神经质维度得分与逻辑推理任务绩效表现出正相关,与简单反应时和警戒任务绩效表现出负相关,精神质维度得分与短时记忆和空间处理任务的绩效表现出正相关,与警戒任务绩效表现出负相关,外向性维度得分与简单计算、空间处理和警戒任务的绩效表现出负相关,撒谎维度得分分别与简单计算、逻辑推理和简单反应时任务的绩效表现出负相关.     

Comparative impact behavior of four long carbon fiber reinforced concretes

The addition of long carbon fibers (fibers more than 10 mm in length) to traditional reinforced concrete is proposed as a method to improve the impact spalling resistance of concrete. A series of experimental tests were conducted to compare the impact resistance of plain concrete (PC), steel reinforced concrete, and four different types of long carbon fiber reinforced concrete (LCFRC) panels. The plain and conventional steel reinforced concrete panels served as control specimens. Of the four types of long carbon fibers tested in this study, the first fiber type consisted of an epoxy-impregnated, bidirectional weave (Type A), while the remaining types consisted of fiber tow with three different variations of a polypropylene support system (Type B). To determine the properties and performance of the LCFRC, experimental testing included a drop weight impact test of the panels as well as a standard ASTM test method for flexural performance of fiber-reinforced concrete. The results from each test in terms of impact energy, time histories of impact load and deflection, strain energy, failure crack pattern, and flexural properties were then compared to one another. This comparison indicated that adding long carbon fibers to concrete increases the post-cracking behavior of the concrete and decreases fragmentation during an impact test. Of the four fibers tested, Fiber Type B3 exhibited the highest performance, absorbing more energy during impact. This result is most likely related to the unique shape of this type of fiber in comparison to the others, which allowed more extensive wetting of the fiber with cement paste and thus improved bond to the cementitious matrix.     

Tensile Properties of Electrodeposited Nanocrystalline FCC Metals

Bulk nanocrystalline Ni and Ni-15wt%Fe alloy were fabricated via electrodeposition techniques. The nominal grain size of nickel samples was varied from 15 to 200 nm by employing different deposition parameters. The grain size was further reduced to 9 nm by alloying nickel with iron. The tensile properties were evaluated at room temperature using dog-bone shaped samples. The results of this study confirm that strength and strain hardening rate increase with decreasing grain size. The fracture behavior was found to depend on the grain size, presence of large and small defects, and the stress state. The tensile elongation and reduction in area varied significantly among the samples and did not correlate with the fracture behavior. Three categories of behavior were identified. In Type I the samples showed completely ductile fracture but very low tensile elongation. In Type II the samples showed a relatively brittle behavior but impressive tensile elongation. In Type III the samples showed ductile behavior with reasonable tensile elongation. In this article, the tensile elongation and the fracture mode of nanocrystalline face centered cubic (FCC) metals are discussed in terms of deformation behavior and presence of defects.     

Fundamental deformation behavior in high-entropy alloys: An overview

High-entropy alloys (HEAs), as a new class of materials, are nearly equiatomic and multi-element systems, which can crystallize as a single phase or multi-phases. Most of the HEAs described in the literature contain multiple phases (secondary phases, nanoparticles, and so on), rather than a single solid-solution phase. Thus, it is essential to review the typical mechanical properties of both single-phase and multiphase HEAs thoroughly, with emphases on (1) the fundamental physical mechanisms and (2) the difference from conventional alloys. In this paper, mainly based on different mechanical properties, HEAs are classified into four types for the first time, i.e., (a) HEA alloy systems of 3d-transition metals only (Type 1), (b) HEA alloy systems of transition metals with larger atomic-radius elements (Type 2), (c) HEA alloy systems of refractory metals (Type 3), and (4) others (Type 4). Then a number of aspects of mechanical behavior are reviewed and discussed, including the elastic anisotropy, yield strength, high-temperature performance, serration behavior, fracture toughness, and fatigue responses, which may serve as a demonstrative summary for the current progress in the scientific research of HEAs. Several mechanisms that quantitatively explain the mechanical properties of single-phase and multiphase HEAs in terms of basic defects (dislocations, twinning, precipitates, etc.) are discussed. A number of future research activities are suggested, based on the emphasis on developing high-performance structural materials. The review concludes with a brief summary of major mechanical properties and insights into the deformation behavior of single-phase and multiphase HEAs. The comparison and contrast between HEAs and conventional alloys remain the most compelling motivation for future studies. With the integrated experimental and simulation investigations, a clearer picture of the fundamental deformation behavior of single-phase and multiphase HEAs could be explored.     

Theory of curved, clamped, piezoelectric film, air-borne transducers

Differential equations in the cylindrical coordinate system have been solved to calculate vibration mode of a curved, clamped, piezoelectric multilayer film. Type I has two clamps at straight ends with uniform film curvature, and Type II has the same two clamps with nonuniform curvature in which the radii are different for the central region and for side regions. The solutions include a uniform displacement term, flexural waves with sinusoidal terms, and a hyperbolic cosine term. By numerical computations, the vibration modes and frequency response of displacement are shown, as are various transducer performances. Mechanical losses of the layer materials were taken as complex Young's moduli with Q values assumed to be constant with frequency. Numerical calculations for 28-/spl mu/m PVDF with 25-/spl mu/m polyester enforcement have shown that (1) the resonance frequency is not necessarily proportional to the inverse of curvature radius as classical theory describes, and, furthermore, resonance diminishes for a certain range of radii, forming a stop band; (2) a back air cavity thinner than 150 /spl mu/m significantly increases the resonance frequency; (3) Type II generates much higher output pressure than Type I; (4) receiver sensitivities for Type I and Type II are not much different; and (5) the effect of radiation impedance is small leading to /spl sim/7% output reduction.     

Age,gender, mileage and the DBQ: The validity of the Driver Behavior Questionnaire in different driver groups

The Driver Behavior Questionnaire (DBQ) is one of the most widely used instruments for measuring self-reported driving behaviors. Despite the popularity of the DBQ, the applicability of the DBQ in different driver groups has remained mostly unexamined. The present study measured aberrant driving behavior using the original DBQ (Reason, J.T., Manstead, A., Stradling, S.G., Baxter, J., Campbell, K., 1990. Errors and violations on the road – a real distinction. Ergonomics, 33 (10/11), 1315–1332) to test the factorial validity and reliability of the instrument across different subgroups of Danish drivers. The survey was conducted among 11,004 Danish driving license holders of whom 2250 male and 2190 female drivers completed the questionnaire containing background variables and the DBQ. Exploratory and confirmatory factor analysis showed that the original three-factor solution, a four-factor solution and a two-factor solution had acceptable fit when using the whole sample. However, fit indices of these solutions varied across subgroups. The presents study illustrates that both the original DBQ and a Danish four-factor DBQ structure is relatively stable across subgroups, indicating factorial validity and reliability of the DBQ. However, as the Danish DBQ structure has an overall better fit, the present study highlights the importance of performing an explorative analysis when applying the DBQ in order to assess the problem areas within a driving population.     

Mechanical,thermal and fire retardation behaviours of nanoclay/vinylester nanocomposites

The dispersion of montmorillonite (MMT) in vinylester for preparing nanoclay/vinylester gel coat was reported. Two sets of MMT/vinylester specimens, namely Type 1 and Type 2, were prepared for comparative studies. Type 1 specimens were prepared using ultrasonication only, and Type 2 specimens were prepared using both ultrasonication and twin-screw extrusion. According to XRD and TEM results, Type 2 specimens showed lower levels of nanoclay agglomeration and higher levels of exfoliation. DSC results showed that the glass transition temperatures of Type 2 specimens are higher than those of Type 1 specimens. TGA results showed that the residual weight of 4 wt.% MMT/vinylester of Type 1 was 7.38%, while the corresponding value of Type 2 was 13.5%, indicating lower thermal degradation in the latter. MMT/vinylester/glass and MMT/vinylester/carbon specimens were fabricated and tested for mechanical and fire retardation behaviours. Type 2 based nanocomposite laminates showed greater values of ultimate tensile strength, flexural strength, interlaminar shear strength, impact strength, horizontal burning rate, and vertical burning rate than Type 1 based laminates. SEM images of tensile fractured surfaces revealed that Type 2 based laminates have no or less agglomeration of nanoclay than Type 1 based laminates.     

Investigation of the precision in X-ray diffraction analysis of VCSEL structures

In principle, the structural components of a vertical cavity surface emitting laser, such as the alloy compositions, and the layer thicknesses, can be obtained from the exact fit of a simulated X-ray diffraction pattern to a measured diffraction pattern. In practice, because of the number of layer and thickness variables in a typical structure, it is unlikely that an exact fit can be achieved within a reasonable timescale. Rather a near fit is a more practical target along with a measure of the precision that a near fit can provide. This paper considers pragmatic strategies for data collection and simulation along with a realistic appraisal of the current capabilities for precision.     

Mechanical effects,antimicrobial efficacy and cytotoxicity of usnic acid as a biofilm prophylaxis in PMMA

Experiments were performed to test the null hypothesis that the addition of a natural occurring antibiotic would not alter mechanical properties of polymethylmethacrylate (PMMA). Compression and four-point bending tests were used to assess mechanical properties of zirconium dioxide bearing bone cement (Type Zr) and barium sulfate bearing bone cement (Type Ba), mixed with the antibiotic usnic acid (“usnic”), used to create a surface resistant to biofilm formation. Addition of usnic had a statistically significant effect on the material properties. Compressive and bending strengths decreased as usnic was added and Type Zr was stronger than Type Ba although material properties remained above recommended minima. With implications of liver toxicity with large doses of usnic taken as a dietary supplement, cytotoxicity tests using bone cement coupons were performed and showed very little or no toxicity in primary cultures of rabbit skin derived fibroblasts. A simple test of usnic’s efficacy as a biofilm prophylaxis in PMMA was also conducted. Bone cement coupons with usnic were tested for their effectiveness against methicillin resistant Staphylococcus aureus. Diminished biofilm formation on usnic-containing coupons indicated that usnic can be an effective anti-microbial agent.     

Omni-directional guided wave transducer arrays for the rapid inspection of large areas of plate structures

Omni-directional guided wave array transducers contain a circular pattern of elements that individually behave as omni-directional point transmitters or receivers. The data set acquired from such an array contains time-domain signals from each permutation of transmitter and receiver. A phased addition algorithm is developed that allows an omni-directional, B-scan image of the surrounding plate to be synthesized from any geometry of array. Numerically simulated data from a single reflector is used to test the performance of the algorithm. The results from an array containing a fully populated circular area of elements (Type I array) are found to be good, but those from an array containing a single ring of elements (Type II array) contain many large side-lobes. An enhancement to the basic phased addition algorithm is presented that uses deconvolution to suppress these side-lobes. The deconvolution algorithm enables a Type II array to equal the performance of a Type I array of the same overall diameter. The effect of diameter on angular resolution is investigated. Experimental data obtained from a guided wave array containing electromagnetic acoustic transducers (EMAT) elements for exciting and detecting the S/sub 0/ Lamb wave mode in a 5-mm thick aluminium plate are processed with both algorithms and the results are discussed.     

Sky-radiance gradient measurements at narrow bands in the visible

Accurate calibrated measurements of the radiance of the daytime sky were made in narrow bands in the visible portion of the spectrum. These measurements were made over several months and were tabulated in a sun-referenced coordinate system. The radiance as a function of wavelength at angles ranging from 5 to 90 deg was plotted. A best-fit inverse power-law fit shows inversely linear behavior of the radiance versus wavelength near the Sun (5 deg) and a slope approaching inverse fourth power far from the Sun (60 deg). This behavior fits a Mie-scattering interpretation near the Sun and a Rayleigh-scattering interpretation away from the Sun. The results are also compared with LOWTRAN models.     

应县木塔残损特征的分析研究

带昂柱头铺作的抗震性能研究是应县木塔抗震性能研究的重要基础。为揭示不同竖向荷载下该类铺作的变形模式和抗震性能,该研究以应县木塔二层明层外槽带昂柱头铺作为原型,制作了2个1∶3.7的缩尺试件,进行了拟静力抗震性能试验。通过分析该铺作的水平力-位移滞回曲线、骨架曲线和等效粘滞阻尼系数等,明确了竖向荷载对该铺作抗震性能指标的影响。结果表明：竖向荷载的变化基本不影响该铺作的变形特征,但竖向荷载的增大会加剧滞回曲线的不对称性,且会显著提高该类铺作的水平承载力、初始刚度和耗能能力。竖向荷载增大3.7倍,水平承载力在正向和负向分别提高了2.2倍和2.9倍,初始刚度提高了2.4倍,耗散能量增加了3.0倍;增大竖向荷载虽然会改变铺作初始滑移出现的位置,但不改变该试验铺作的滑移累积方式和薄弱位置,最终两个铺作的滑移模式都表现为两跳华栱间的相对滑移。提出了该铺作节点的位移-承载力骨架曲线简化模型,得到了不同竖向荷载对抗侧刚度和水平承载力的影响系数β_k和β_F,用以修正骨架曲线简化模型在不同竖向荷载下的刚度k。

     

Evaluation of sandwich panels with various polyurethane foam-cores and ribs

The objective of this study was to evaluate three potential core alternatives for glass fiber reinforced polymer (GFRP) foam-core sandwich panels. The proposed system could reduce the initial production costs and the manufacturing difficulties while improving the system performance. Three different polyurethane foam configurations were considered for the inner core, and the most suitable system was recommended for further prototyping. These configurations consisted of high-density polyurethane foam (Type 1), a bidirectional gridwork of thin, interconnecting, GFRP webs that is in-filled with low-density polyurethane foam (Type 2), and trapezoidal-shaped, low-density polyurethane foam utilizing GFRP web layers (Type 3). The facings of the three cores consisted of three plies of bidirectional E-glass woven fabric within a compatible polyurethane resin. Several types of small-scale experimental investigations were conducted. The results from this study indicated that the Types 1 and 2 cores were very weak and flexible making their implementation in bridge deck panels less practical. The Type 3 core possessed a higher strength and stiffness than the other two types. Therefore, this type is recommended for the proposed sandwich system to serve as a candidate for further development. Additionally, a finite element model (FEM) was developed using software package ABAQUS for the Type 3 system to further investigate its structural behavior. This model was successfully compared to experimental data indicating its suitability for parametric analysis of panels and their design.     

Model for quantum scattering of rotons. I. Hard-sphere interaction

A new model is proposed for the behavior of rotons. We postulate a linear Schrödinger equation with a hypothetical Hamiltonian fit to the dispersion relation and treat the three-dimensional scattering problem. All calculations are done in closed form. As an example, we study scattering by a hard sphere, which yields the same result as that obtained in the high-energy limit of the usual Schrödinger equation. The calculated mobility gives a reasonable fit to the radii of both positive and negative ions.Research sponsored in part under Contract No. F44620-68-C-0075.     

可展开薄膜结构折叠方式和展开过程研究

薄膜材料广泛运用于太空可展开航天器,薄膜的折叠和展开分析是其中的关键技术。从树叶的仿生学出发,提出薄膜结构的几种折叠方式。建立弹簧-质点系统描述薄膜材料,模拟薄膜结构的展开过程。薄膜展开过程中薄膜不可避免地发生自身的接触碰撞,提出了自接触对的判别准则,采用罚函数法有效地解决薄膜自接触问题。分析了三种折叠方式的薄膜的展开过程,并进行比较,叶外折叠方式和Miura折叠法比较适合平面薄膜的折叠。     

Combining mechanical interlocking,force fit and direct adhesion in polymer–metal-hybrid structures – Evaluation of the deformation and damage behavior

The joint of long fiber reinforced thermoplastic polymer–metal-hybrid structures is evaluated. For this the deformation and damage behavior of joints combining mechanical interlocking, force fit and direct adhesion is determined experimentally. Results show that each joining mechanism results in a specific deformation and damage behavior. Experimental results also show that the behavior of the combination is dependent on the interaction of the single joining mechanisms. With finite element simulations the deformation and damage behavior of joints with combined mechanism has been evaluated beyond the tested configurations. It is demonstrated how the developed simulation tool can be used to support the selection of the best joint configurations.     

Spotlighting: Emergent Gender Bias in Undergraduate Engineering Education

“Spotlighting” is the singling out of women by gender in ways that make them uncomfortable. It has three forms: Type I is singling out with the intention to harm (overt sexism); Type II is doing so with neutral intentions (tacit sexism); and Type III, a new type of gender bias, is singling out women with the intention to help them. In a longitudinal, qualitative study including three types of schools, undergraduate women engineers named Type III spotlighting due to women in engineering (WIE) programs as the direct or indirect cause of their primary gender‐bias difficulties. Two changes to WIE programs are suggested to reduce Type III spotlighting: (1) offer their benefits either to all students or based on academic, not demographic, criteria, and (2) expand WIE programs to “conduct in engineering” programs that would emphasize pre‐emption of non‐professional behavior, and would be more inclusive of other biases.     

Torque transmission capability of composite–metal interference fit joints

In this paper the performance of an interference fit joint between a composite tube and a steel shaft under torsional load was investigated. Some important design parameters on the interference fit joint were presented and addressed based on the results from analytical and numerical models. The stress state of the joint under torsional load with contact elements was calculated by three dimensional finite element analysis. For the long term use of the interference joint the viscoelastic behavior of the composite tube was also considered through the analytical model. Finally the validity of analysis of the interference fit joint was experimentally examined.