Conspicuity, memorability, comprehension, and priming in road hazard warning signs

This study assessed driver reactions to 16 road hazard warning signs of various formats by projecting life-sized video of road scenes to drivers in a driving simulator. A range of measures, including attentional and search conspicuity, implicit and explicit recognition, dynamic and static comprehension, and sign priming were collected. Of the signs tested, road works and school warning signs were most often detected, remembered, and understood. Slippery surface warnings were associated with some of the lowest detection and comprehension rates. The effectiveness of the different formats depended on the type of hazard sign. In the case of road works warnings, a flashing variable message format was only slightly more conspicuous than the large dimension format, equal in comprehensibility, and perhaps somewhat worse in terms of memorability. For the school warnings, however, the flashing variable message format appeared to convey a greater sense of potential hazard, produced superior search conspicuity and priming, and was equal in terms of memorability and comprehensibility. The range of measures worked well as a whole with the two measures of conspicuity and the measure of static comprehension showing the greatest consistency.     

A suggested color scheme for reducing perception-related accidents on construction work sites

Changes in workforce demographics have led to the need for more sophisticated approaches to addressing the safety requirements of the construction industry. Despite extensive research in other industry domains, the construction industry has been passive in exploring the impact of a color scheme; perception-related accidents have been effectively diminished by its implementation. The research demonstrated that the use of appropriate color schemes could improve the actions and psychology of workers on site, thereby increasing their perceptions of potentially dangerous situations. As a preliminary study, the objects selected by rigorous analysis on accident reports were workwear, safety net, gondola, scaffolding, and safety passage. The colors modified on site for temporary facilities were adopted from existing theoretical and empirical research that suggests the use of certain colors and their combinations to improve visibility and conspicuity while minimizing work fatigue. The color schemes were also tested and confirmed through two workshops with workers and managers currently involved in actual projects. The impacts of color schemes suggested in this paper are summarized as follows. First, the color schemes improve the conspicuity of facilities with other on site components, enabling workers to quickly discern and orient themselves in their work environment. Secondly, the color schemes have been selected to minimize the visual work fatigue and monotony that can potentially increase accidents.     

A scheme to randomly generate surface dust points for the 3D complex variable boundary element method (CVBEM)

A scheme to randomly generate dust points on the surface of a three-dimensional (3D) object is proposed. This scheme will potentially eliminate the bias of a density of points which are approximately equally spaced on the surface, as well as eliminate possible weighting requirements for areas of higher density. This method has the potential to reduce computational effort, as fewer points might be required to define the surface area. The global trial function vector can be assigned to these dust points and then entered into the complex variable boundary element method (CVBEM) commercial code. This scheme can be applied to each piece of a system that is comprised of a connected multiple geometry. A noticeable benefit of this approach is that the same problem can be studied several times, using a new random distribution of surface points each time. The smallest error can then be determined and that run selected. The Mathematica code used to generate the scheme is attached as an appendix.     

彩色合成中AOM设计分析

利用铌酸锂晶体为压电换能器,熔石英为声光互作用介质,研制出调制速度为32MHz、工作频率为180MHz、渡越时间为15ns、用于RGB彩色合成中的的声光调制器,文中主要讨论和分析了Q参数与调制器中心工作频率、换能器长度的关系;讨论了R参数对衍射光束形状的影响及与衍射效率的关系,还讨论并确定了换能器最佳尺寸,经测试,高速率声光调制器衍射效率为47％,并测试了调制速度。     

The effect of chevron alignment signs on driver performance on horizontal curves with different roadway geometries

To develop a practicable and clear guideline for implementing Chevrons on China’s highways, it is necessary to understand the effect of Chevrons on driving performance in different roadway geometries.Using a driving simulator, this study tests the effect of China’s Chevrons on vehicle speed and lane position on two-lane rural highway horizontal curves with different roadway geometries.The results showed a significant effect of Chevrons on speed reduction, and this function was not significantly affected by curve radius but was statistically affected by curve direction. The speed reduction caused by Chevrons was also significant at the approach of curve, middle of curve and point of tangent. The 85th percentile speed was also markedly lower when Chevrons were present. We also found a significant effect of Chevrons in encouraging participants to drive the vehicle with a more proper lane position at the first half of curves; and this function was slightly affected by curve radius. Meanwhile, the effect of Chevrons on keeping drivers staying in a more stable lane position was also statistically significant at the second half of curves. In sharp curves, the function of Chevrons to make drivers keep a stable lane position was lost. Besides, the impact of curve direction on the function of Chevrons on lane position was always present, and drivers would drive slightly away from Chevrons.Regardless of the curve radius, China’s Chevrons at horizontal curves provide an advance warning, speed control and lane position guide for traffic on the nearside of Chevrons. Besides, combing with the function of Chevrons on preventing excessive speed and the benefit to make drivers keep a more proper lane position, China’s Chevrons appear to be of great benefit to reduce crashes (e.g., run-off-road) in curves.     

Necessary and sufficient invariance conditions in mismatched uncertain variable structure systems

Abstract

This paper investigates new invariance conditions in mismatched uncertain variable structure systems associated with a new sliding mode control, at the same time, retaining the benefits achieved in conventional variable structure systems design, namely, fast response, good robustness, and stability. Based on new equivalent state idea and two sets of switching surfaces, necessary and sufficient invariance conditions are derived such that matched and mismatched uncertainties completely vanish from the sliding mode dynamics. In terms of linear matrix inequalities, we give explicit formulas of linear switching surfaces to guarantee that the system in the new sliding mode is quadratically stable. Additionally, we give a control law to perform the new sliding mode. Finally, a numerical example is given to illustrate the effectiveness of the proposed approach.     

Natural modes of vibration of variable stiffness composite laminates with curvilinear fibers

In this paper, natural frequencies and vibrational mode shapes of variable stiffness composite laminate (VSCL) plates with curvilinear fibers are studied. In each ply of this rectangular VSCL, the fiber-orientation angle changes linearly with respect to the horizontal coordinate. To define the modes of vibration of the laminates, a new p-version finite element, which follows third-order shear deformation theory (TSDT), is employed. The convergence properties of this new element are investigated. Taking manufacturing restrictions regarding the fiber curvatures into account, maps of natural frequencies as functions of tow-orientation angles are determined in demonstrative examples. It is verified that the use of curvilinear fibers instead of the traditional straight fibers introduces a greater degree of flexibility, which can be used to adjust frequencies and mode shapes.     

Thermal performance of multilayer insulation around a horizontal cylinder

Thermal performance of multiplayer insulation (MLI) is affected by contact pressure between adjacent layers. In order to evaluate the thermal performance of the MLI fabricated in the horizontal cryostats of superconducting magnets, it is important to investigate the contact pressure in the MLI. In case of a horizontal cryostat, the MLI is wound around horizontal cylindrical surface and is compressed at the upper part of the cylinder due to the MLI self-weight. At first, a single thin film wound around the horizontal cylinder was analyzed to evaluate the contact pressure acting on the cylinder. The analysis has been extended to the multiply wound film around horizontal cylinder, in order to investigate the distribution of contact pressure between adjacent layers. By using experimental data obtained with a flat panel calorimeter, the results of this analysis have been applied to evaluate the thermal performance of MLI around a horizontal cylinder. And the non-dimensional contact pressure parameter P^* has been introduced as a useful parameter to evaluate and compare the thermal performance among different kinds of MLI.     

浅谈南京地铁一号线BAS系统的节能效应

南京地铁一号线环境监控BAS系统的设计以“安全、可靠、节能”为原则,采用变频调速实现对车站大空调系统的变风量控制,同时应用后台软件EnCs对车站通风空调系统等的模式进行了优化,起到了节能效应。本文从理论分析与实际应用所得数据测算相结合,对南京地铁一号线BAS系统节能效果进行了分析,同时也指出了应用中存在的不足与矛盾。     

LY12铝合金表面有机-无机杂化膜特性研究

作为-种有机-无机杂化材料,倍半硅氧烷(SSO)近年来被发现其具有良好的防腐性能,并有望成为传统的防腐材料-铬酸盐转化膜的替代物.本文用乙烯基三甲氧基硅烷(VMS)通过溶胶凝胶法制得了SSO,并涂敷于LY12铝合金表面.用(EIS)对不同水解时间下制得的VMS膜层的结构进行了表征.水解3d所获得的VMS在不同固化时间下的EIS谱图上出现了一个新的时间常数,证实了在VMS膜层与铝合金基体之间产生了一个新的中间层.根据实际的可能性,该层包含Al-O-Si,膜层与基体以化学键合;然而,完全水解的VMS膜层的EIS谱图中没有这个新的时间常数.不同水解时间的VMS膜层的EIS谱图表明为获得致密的膜层且与基体间以化学键合,VMS需在本文反应条件下水解3d.     

Variable delays and message losses: Influence on the reliability of a control loop

Today, new technologies (distributed systems, networks communication) are more and more integrated for applications needing to fit real-time and critical constraints. It means that we require more and more to integrate these new technology-based components in systems or sub-systems dedicated to safety or dealing with a high level of criticality.Control systems are generally evaluated as a function of required performances (overshoot, rising time, response time) under the condition to respect a stability condition. Reliability evaluation of such systems is not trivial, because generally classical methods do not take into account time and dynamic properties which are the bases of control systems.The methodology proposed in this paper deals with an approach for the dependability evaluation of control systems, based on Monte-Carlo simulation, giving a contribution to the integration of automatic control and dependability constraints.     

全序时态模式下函数依赖集的成员籍问题研究

时态函数依赖(TFD)约束的全序时态模式下, 成员籍问题是设计有效模式分解算法的关键.定义了全序时态模式下全序时态函数依赖集有效闭包、属性集在给定时态类型上的闭包、属性集的闭包等概念,根据这些概念,结合全序时态模式自身的特点,提出求全序时态模式下属性集在给定时态类型上的闭包以及时态函数依赖(TFD)集成员籍问题的算法,证明了算法的可终止性和正确性,分析算法的时间复杂性,为时态函数依赖环境下全序时态模式的进一步规范化提供了理论基础.     

Thermodynamic analysis on the performance of a variable speed scroll compressor with refrigerant injection

A thermodynamic model for a variable speed scroll compressor with refrigerant injection was developed using continuity, energy conservation and real gas equation. The model included energy balance in the low-pressure shell compressor, suction gas heating, motor efficiency, and volumetric efficiency considering gas leakages as a function of compressor frequency. The developed model was verified by comparing the predicted results for the no injection condition with the experimental data. The deviations of the predicted from the measured values were within 10% for approximately 90% of the experimental data. Based on the model, mass flow rate, suction gas heating, cooling capacity and power consumption of the compressor were estimated and analyzed as a function of frequency. The effects of refrigerant injection on the performance of the compressor were also discussed as a function of frequency, injection conditions, and injection geometry.

Résumé

A thermodynamic model for a variable speed scroll compressor with refrigerant injection was developed using continuity, energy conservation and real gas equation. The model included energy balance in the low-pressure shell compressor, suction gas heating, motor efficiency, and volumetric efficiency considering gas leakages as a function of compressor frequency. The developed model was verified by comparing the predicted results for the no injection condition with the experimental data. The deviations of the predicted from the measured values were within 10% for approximately 90% of the experimental data. Based on the model, mass flow rate, suction gas heating, cooling capacity and power consumption of the compressor were estimated and analyzed as a function of frequency. The effects of refrigerant injection on the performance of the compressor were also discussed as a function of frequency, injection conditions, and injection geometry.     

Framing the performance of induced magnetic field and entropy generation on Cu and TiO2 nanoparticles by using Keller box scheme

Aim of present communication is to inspect the impact of induced magnetic field and entropy generation on water based nanofluid. The thermal characteristic of nanofluids are explored using copper and titanium nanoparticles. The governing physical problem is modelled and by using scaling group of transformations. Obtained system of coupled nonlinear partial differential equations is converted into set of ordinary differential equations. These equations are solved numerically using implicit finite difference scheme. Entropy generation analysis is carried out to measure the disorder within the thermodynamical system. Effect of nanoparticles volume fraction on magnetic field components, skinfriction and local heat flux are computed and discussed in a physical manner. It is examined that magnetic field parameter reduces wall stress while it increases rate of heat transfer at surface. Local heat flux accelerate with increasing nanoparticles volume fraction. ${\text{TiO}}_2$ water based nanofluid showed better results for heat transfer than $\text{Cu}$ water based nanofluid.     

Temporal perspective on individual driver behavior using electronic records of undesirable events

This paper explores In-Vehicle Data Recorders (IVDRs) information about the count of undesirable driving events (such as hard braking, lane changing, and sharp turning) of 148 individuals. The information was logged over three years and included time stamp information about the occurrence of undesirable driving events in each trip (N = 573,238). The objective was to gain deeper understanding about the heterogeneity among drivers with respect to behavior change over time, the effect of trip duration and the distribution of events count. Our findings show that in some respects drivers are similar: for all drivers, the variance of the events count was larger than the mean, indicating that the negative binomial distribution is suitable to model the distribution of events count per trip. Most drivers (95%) had lower events rate during longer trips, suggesting that a ‘simple’ events rate index is problematic when comparing between those driving longer trips and drivers driving short trips. In addition, most drivers (87%) improved their driving behavior throughout the measurement period. However, there are important differences among drivers in terms of the frequency of behavior change and the trends in behavior over time. These findings demonstrate the need for personalized examination of individual drivers. Several tools for such personalized examination were developed and discussed in this study.     

Multi-job production systems: definition,problems, and product-mix performance portrait of serial lines

This paper pursues two goals: (a) Define a class of widely used in practice flexible manufacturing systems, referred to as Multi-Job Production (MJP) and formulate industrially motivated problems related to their performance. (b) Provide initial results concerning some of these problems pertaining to analysis of the throughput and bottlenecks of MJP serial lines as functions of the product-mix. In MJP systems, all job-types are processed by the same sequence of manufacturing operations, but with different processing time at some or all machines. To analyse MJP with unreliable machines, we introduce the work-based model of production systems, which is insensitive to whether single- or multi-job manufacturing takes place. Based on this model, we investigate the performance of MJP lines as a function of the product-mix. We show, in particular, that for the so-called conflicting jobs there exists a range of product-mixes, wherein the throughput of MJP is larger than that of any constituent job-type manufactured in a single-job regime. To characterise the global behaviour of MJP lines, we introduce the Product-Mix Performance Portrait, which represents the system properties for all product-mixes and which can be used for operations management. Finally, we report the results of an application at an automotive assembly plant.     

A variable selection method based on uninformative variable elimination for multivariate calibration of near-infrared spectra

Variable (or wavelength) selection plays an important role in the quantitative analysis of near-infrared (NIR) spectra. A modified method of uninformative variable elimination (UVE) was proposed for variable selection in NIR spectral modeling based on the principle of Monte Carlo (MC) and UVE. The method builds a large number of models with randomly selected calibration samples at first, and then each variable is evaluated with a stability of the corresponding coefficients in these models. Variables with poor stability are known as uninformative variable and eliminated. The performance of the proposed method is compared with UVE-PLS and conventional PLS for modeling the NIR data sets of tobacco samples. Results show that the proposed method is able to select important wavelengths from the NIR spectra, and makes the prediction more robust and accurate in quantitative analysis. Furthermore, if wavelet compression is combined with the method, more parsimonious and efficient model can be obtained.     

A simple spatial integration scheme for solving Cauchy problems of non-linear evolution equations

In this study, we address a new and simple non-iterative method to solve Cauchy problems of non-linear evolution equations without initial data. To start with, these ill-posed problems are analysed by utilizing a semi-discretization numerical scheme. Then, the resulting ordinary differential equations at the discretized times are numerically integrated towards the spatial direction by the group-preserving scheme (GPS). After that, we apply a two-stage GPS to integrate the semi-discretized equations. We reveal that the accuracy and stability of the new approach is very good from several numerical experiments even under a large random noisy effect and a very large time span.     

Effects of vacuum thermal cycling on mechanical and physical properties of high performance carbon/bismaleimide composite

The aim of this article was to investigate the effects of vacuum thermal cycling on mechanical and physical properties of high performance carbon/bismaleimide (BMI) composites used in aerospace. The changes in dynamic mechanical properties and thermal stability were characterized by dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA), respectively. The changes in linear coefficient of thermal expansion (CTE) were measured in directions perpendicular and parallel to the fiber direction, respectively. The outgassing behavior of the composites were examined. The evolution of surface morphology and surface roughness were observed by atomic force microscopy (AFM). Changes in mechanical properties including transverse tensile strength, flexural strength and interlaminar shear strength (ILSS) were measured. The results indicated that the vacuum thermal cycling could improve the crosslinking degree and the thermal stability of resin matrix to a certain extent, and induce matrix outgassing and thermal stress, thereby leading to the mass loss and the interfacial debonding of the composite. The degradation in transverse tensile strength was caused by joint effects of the matrix outgassing and the interfacial debonding, while the changes in flexural strength and ILSS were affected by a competing effect between the crosslinking degree of resin matrix and the fiber-matrix debonding.     

天然纤维粉体对聚偏氟乙烯多孔膜结构与性能的影响

采用溶液相转化法制备了羽绒粉体/聚偏氟乙烯（PVDF）和苎麻粉体/PVDF复合微孔膜,对膜结构和性能进行了分析和测试。结果显示苎麻粉体/PVDF复合膜、羽绒粉体/PVDF复合膜、纯PVDF膜的形态一致,均为致密皮层和多孔亚层,孔隙率和水通量依次降低,结晶度依次增加;但膜的吸水率按照羽绒粉体/PVDF复合膜、苎麻粉体/PVDF复合膜、纯PVDF膜依次下降;这说明复合膜水通量主要受孔隙率的影响,而膜吸水率主要受纤维粉体吸水性大小的影响。膜力学性能测试显示加入粉体之后,PVDF膜的强度增加,断裂伸长率有所下降。