Head-up displays assist helicopter pilots landing in degraded visual environments

Civilian rotary-wing aircraft pilots typically rely on visual information from the external environment to guide flight, but are increasingly required to operate in degraded visual environments. The current study evaluated the impact of a head-up display (HUD) upon pilot performance, perceived situation awareness and workload. A 2 × 2 repeated measures design required qualified rotary-wing pilots (N = 6) to fly in clear and degraded visual conditions both with and without the HUD. In degraded visual conditions, the HUD significantly improved pilot perceived situation awareness whilst simultaneously reducing workload. Objective flight technical performance data offered preliminary support for a positive change in pilot behaviour when using the HUD in degraded visual conditions.     

Modeling exposure period for solar disinfection (SODIS) under varying turbidity and cloud cover conditions

Solar disinfection (SODIS) is widely practiced all around the world. The process requires variable exposure periods depending upon a number of process parameters (e.g., water turbidity, atmospheric temperature, and cloud cover conditions). This paper describes the development of a mathematical model to estimate required exposure period to achieve Fecal coliforms (FCs) removal for changing process parameters. Daily and hourly solar radiation were estimated and found to be suitable for SODIS application with intensity of 500 W/m² over a period of 3–5 h/day. Randomized SODIS experiments over a period of 3 years were conducted to consider seasonal and weather variations. Six samples each for five levels of turbidity (0, 5, 10, 20, and 30 NTU) were exposed to sunlight under variable cloud cover conditions on different days during the 3-year sampling period. Samples were collected and analyzed for remaining FCs at different intervals in each sampling day. Analysis of variance revealed that turbidity and percent of cloud cover are the most significant process parameters. It was found that FCs die-off in SODIS bottles followed the first-order kinetics. Different data sets were used for the development and calibration of the model. The calibrated model was further verified against the literature. Simple characteristics curves have also been established for practical application at household level to estimate exposure periods. The study revealed a significant difference between the required exposure periods for different turbidity and cloud cover conditions.     

Chemical Characterization of Cobalt Crust from Afanasy-Nikitin Seamount in the Eastern Indian Ocean by Inductively Coupled Plasma Time-of-Flight Mass Spectrometry

Analytical methodology was developed for the chemical characterization of cobalt crust samples collected from the Afanasy-Nikitin seamount in Eastern Equatorial Indian Ocean by inductively coupled plasma time-of-flight mass spectrometry (ICP-TOF-MS). Concentrations of geochemically significant groups of different trace elements such as large-ion-lithophile elements (e.g., Rb, Cs), high field strength elements (e.g., Ta, Nb, Hf and Zr), rare earth elements in addition to a few major and minor elements were determined in these samples. Samples (~50 mg) were digested in closed digestion vessels for 48 h before the expulsion of Si and the residues were taken in 5 % nitric acid. ¹⁰³Rh was used as an internal standard. Matrix matching external calibrations were utilized in order to compensate for the spectroscopic and non-spectroscopic interferences. The detection limits obtained for various elements were in the range 1–0.01 ng/ml for majority of the elements analyzed. Accuracy for the determination of different elements is assessed by measuring them in a few cobalt crust samples, ferromanganese nodules and similar marine sediment reference materials. Also, there is a very good agreement between the data sets obtained by ICP-TOF-MS as well as the well established ICP-quadrupole MS on cobalt crust samples. The precisions obtained in this study are <5 % RSD for majority of the elements with comparable accuracy. The results are in agreement with certified and reference values wherever available for comparison. The geochemical characteristics of these rare marine sediments have been described.     

Green synthesis of zinc oxide nanoparticles using <Emphasis Type="Italic">Citrus sinensis</Emphasis> extract

This work addresses a low cost, non-toxic green synthesis of zinc oxide nanoparticles prepared using different amounts of Citrus sinensis extract. The zinc oxide nanoparticles presented the Zn–O bond at 618 cm^?1, a crystalline growth in a purely hexagonal wurtzite crystal structure, and different size and shape homogeneity depending on the amount of extract used. The band gap of the ZnO was at around 2.91 eV for all samples. The photocatalytic degradation studies were carried out using methylene blue with the zinc oxide nanoparticles under UV light; where sample M2 presented a degradation of around 83% at 120 min. These results presented a better degradation rate than commercially available zinc oxide nanoparticles.     

Monitoring drivers’ mental workload in driving simulators using physiological measures

Many traffic accidents are caused by, or at least related to, inadequate mental workload, when it is either too low (vigilance) or too high (stress). Creating variations in mental workload and accident-prone driving for research purposes is difficult in the real world. In driving simulators the measurement of driver mental workload is relatively easily conducted by means of physiological measures, although good research skills are required and it is time-consuming. The fact that modern driving simulator environments are laboratory-equivalent nowadays allows full control with respect to environmental conditions, scenarios and stimuli, and enables physiological measurement of parameters of mental workload such as heart rate and brain activity. Several examples are presented to illustrate the potential of modern high-standard driving simulator environments regarding the monitoring of drivers’ mental workload during task performance.     

Temperature sensors based on multimode chalcogenide fibre Bragg gratings

In this work, a theoretical study was conducted on temperature sensing in Ge–Sb–Se multimode fibre Bragg grating (MM-FBG). The sensing characteristics of the designed MM-FBGs with different fibre parameters and operating wavelengths were calculated using a coupled model method. The temperature sensitivity of this MM-FBG was found to improve significantly by shifting the operating wavelength from telecom range to mid-infrared (MIR) and utilizing the wide transmission range of Ge–Sb–Se glasses. The temperature sensitivity of the proposed Ge–Sb–Se MM-FBG was calculated to be 0.0758 nm/°C at 1550 nm, which is 7.58 times higher than silica FBGs at 1550 nm, and the temperature sensitivity was calculated to be more than 0.16 nm/°C at 3390 nm, which is 2.2 times higher than that at 1550 nm. In addition, the proposed MM-FBGs provided multi-peak information, and the sensitivity of each peak was calculated to be comparable to the single-mode FBG. The proposed Ge–Sb–Se MM-FBG has great potential for temperature sensing in MIR because of its advantages of simple preparation, high coupling efficiency, multi-peak information and wide working window.     

Usage versus citation behaviours in four subject areas

This study puts an emphasis on the disciplinary differences observed for the behaviour of citations and downloads. This was exemplified by studying citations over the last 10 years in four selected fields, namely, arts and humanities, computer science, economics, econometrics, and finance, and oncology. Differences in obsolescence characteristics were studied using synchronic as well as diachronic counts. Furthermore, differences between document types were taken into consideration and correlations between journal impact and journal usage measures were calculated. The number of downloads per document remains almost constant for all four observed areas within the last four years, varying from approximately 180 (oncology) to 300 (economics). The percentage of downloaded documents is higher than 90 % for all areas. The number of citations per document ranges from one (arts and humanities) to three (oncology). The percentages of cited documents range from 40 to 56 %. According to our study, 50–140 downloads correspond to one citation. A differentiation according to document type reveals further download- and citation-specific characteristics for the observed subject areas. This study points to the fact that citations can only measure the impact in the ‘publish or perish’ community; however, this approach is neither applicable to the whole scientific community nor to society in general. Downloads may not be a perfect proxy to estimate the overall usage. Nevertheless, they measure at least the intention to use the downloaded material, which is invaluable information in order to better understand publication and communication processes. Usage metrics should consider the unique nature of downloads and ought to reflect their intrinsic differences from citations.     

Interfacial study of Crofer 22 APU interconnect-SABS-0 seal glass for solid oxide fuel/electrolyzer cells

In planar solid oxide fuel and electrolyzer cells, compatibility and thermochemical stability of interconnect-seal glass interface is essential in order to avoid mixing and leakage of different gases and degradation of cell performances. In the present work, interfacial compatibility and thermochemical stability are studied for an alkaline earth silicate based glass (SABS-0) and Crofer 22 APU interconnect system with respect to thermal treatment temperature (700–850 °C) and time (0–100 h). The study has been carried out in argon to avoid complications from oxidation. Even though pore and crack-free interface is obtained and maintained for all the thermal treatment conditions, there are simultaneous diffusion of the Crofer 22 APU and the SABS-0 glass elements, chemical reaction at the Crofer 22 APU/SABS-0 interface, and devitrification of the SABS-0 glass itself.     

自动驾驶中基于透明度的人机界面设计研究

目的 选取自动驾驶中后方来车的典型场景,探究基于透明度人机界面（HMI）设计对驾驶员认知的影响。方法 采取文献查阅、场景分析、实验评估等研究方法,使用态势感知的透明度（SAT）理论模型,设计了该场景下的HMI界面,并在驾驶模拟器上进行了设计验证。结果 研究结果表明HMI透明度水平与驾驶员对系统的信任度呈正相关,但感知工作量无显著变化。另外,不同水平的透明度信息会影响驾驶员的态势感知能力,而驾驶员对当前情境的理解与信任度存在显著相关性。结论 HMI的透明度设计会从三个方面影响驾驶员的认知,分别是态势感知、工作负荷和信任度。因此在对人机界面进行透明度设计时,需要重点考虑对这些因素的影响。     

Thermophysical Properties of Five Binary Copper–Nickel Alloys

Thermophysical properties (e.g., specific enthalpy, heat of fusion, electrical resistivity, thermal volume expansion) are measured in the liquid phase up to very high temperatures by an extreme fast pulse-heating method. Heating rates of about 10⁸ K · s^?1 are applied by self-heating of wire-shaped metallic specimens with a current of approximately 10,000 A. Pure elements seem to be still close to thermal equilibrium as the obtained results are in good agreement with those obtained by static methods. However, this situation might be different for alloys. The rapid volume heating can shift diffusion-controlled phase transitions at heating to higher temperatures or even make them not noticeable anymore. The simple binary Cu–Ni system was chosen to test the heating rate dependence; this system is well known and shows complete miscibility in the liquid and solid ranges of interest. This study is a further step to test the performance of the fast pulse-heating method being applied to simple and more complex alloys. Measured results of enthalpy, heat of fusion, heat capacity, and electrical resistivity in the vicinity of the melting range are presented. The results of enthalpy and heat capacity agree with simple mixing rules. The measured electrical resistivity of different compositions is compared to results obtained by electromagnetic levitation measurements.     

Evaluation of performance measures for representing operational objectives of a mixed model assembly line balancing problem

Performance evaluation of a mixed model assembly line is complicated in nature. For some configurations of the mixed model line, operational objectives can directly be evaluated; however, in others some performance measure is required for evaluating the operational objective. This paper reports a comprehensive comparative study of performance measures as to their relevance in representing the operational objectives of a mixed model assembly line balancing problem of type II. Two performance measures are proposed in this work. A genetic algorithm has been developed for comparing the proposed measures with eight others in an effort to investigate their ability to equalize workload along with minimizing cycle time. Through statistical analysis, one of the proposed performance measures has been established to perform better than the others. Application of the performance measures to balance an assembly line taken as part of an industrial case study also corroborates the results obtained by statistical analysis.     

Neumann exterior wave propagation problems: computational aspects of 3D energetic Galerkin BEM

In this work, we consider as model problem an exterior 3D wave propagation Neumann problem reformulated in terms of a space–time hypersingular boundary integral equation with retarded potentials. This latter is set in the so-called energetic weak form, recently proposed in Aimi et al. (Int J Numer Methods Eng 80:1196–1240, 2009; CMES 58:185–219, 2010), regularized as in Frangi (Int J Numer Methods Eng 45:721–740, 1999) and then approximated by the Galerkin boundary element method. Details on the discretization phase and, in particular, on the computation of integrals, double in time and double in space, constituting the elements of the final linear system matrix are given and analyzed. Various numerical results and simulations are presented and discussed.     

The influence of chromium on early high temperature corrosion of ferritic alloys under SO2 atmosphere

Comprehensive insights into the early stages of corrosion mechanisms provide fundamental knowledge to further understand and model long time material behaviour. The present work studies the early stages of combined oxidation and sulphidation of ferritic model alloys for time scales up to 250 h at 650°C to observe the influence of chromium during the corrosion under SO₂. Model alloys were used to focus on the reaction of the intended elements: Fe, Cr, S, and O. Pure iron simultaneously forms magnetite and iron-sulphide in an early stage of corrosion, covered by a pure oxide layer after 100 h. Iron with 13 wt-% Cr shows hematite and mixed Fe–Cr-oxides first, before sulphides nucleate in the inner corrosion zone. With increasing ageing time a magnetite layer is observed below the hematite layer. Quantitative phase fractions of all corrosion products observed were determined from cross section images. Characterisation of the Fe13Cr corrosion scale by FIB revealed a highly porous structure in the inner corrosion zone where Cr-rich (Fe, Cr)-sulphides are present, and caused the scale to spall easily.     

Analytical and experimental study on thermal conductivity of hardened cement pastes

Thermal conductivity of hardened cement pastes (hcps) in a wide range of water–cement ratio (w/c) is quantitatively investigated using a transient plane source measurement technique. Alkyl alkoxysilane and rapeseed oil were also added to determine the effect of internal hydrophobation on thermal conductivity of solid structure of hcps. The measurements were performed after drying at 50 and 105 °C as well as water submersion. A nonlinear relation was observed between thermal conductivity and w/c which is in alignment with Powers’ model. Samples dried at 50 °C still contained some moisture which increased thermal conductivity up to 11 % compared to samples dried at 105 °C. Furthermore, hydrophobic agents reduced thermal conductivity of dried samples up to 9 % which indicates the reduction in thermal conductivity of solid structure and is in line with observations by scanning electron microscope. A three phase model which can predict thermal conductivity of plain and hydrophobed hcps at different moisture states is presented by exploiting composite models and Hashin–Shtrikman bounds.     

情境意识理论在驾驶界面设计中的研究现状与展望

目的 针对列车驾驶自动化和智能化的发展带来驾驶界面信息量大增,司机工作转变为信息监控和决策后,带来的心理负荷明显上升且情境意识下降等问题,梳理情境意识理论在智能驾驶界面设计中的研究现状,并对下一步研究进行展望。方法 进行文献分析,整理情境意识理论的研究现状和进展,从情境意识与自动化驾驶界面设计、显控界面图文信息、工作负荷、自动化下的人机交互四个具有智能化驾驶界面显著特征的相关设计应用的研究入手,对相关研究成果进行了综述。结论 分析了目前的研究现状和发展方向,提出了应加强对智能化背景下司机的驾驶人机交互认知特征、驾驶情境意识的表现特征及视觉策略、基于情境意识增强的智能列车驾驶界面可视化设计方法等方面的研究。     

澳门公务人员工作压力与心理健康的关系研究

本文通过采用自编的澳门公务员工作压力问卷和SCL-90对295名澳门公务员进行调查,探讨澳门公务员工作压力状况及工作压力与心理健康状况之间的关系。结果发现,公务员的工作压力源依次是工作负荷、决策参与度、工作前景和人际关系;公务员的心理健康状况与工作压力呈显著正相关;恐怖和精神病因子对工作压力有负向预测作用,抑郁、偏执和强迫症状因子对工作压力有正向预测作用。     

Thermal and electrical conductivity of binary magnesium alloys

Thermal conductivity is a key parameter for thermal design and management of the electronic components in their passive cooling processes. In this work, thermal and electrical conductivities of six groups of binary Mg alloys (Mg–Al, Mg–Zn, Mg–Sn, Mg–Zr, Mg–Mn, and Mg–Ca) in as-cast, as-solution, and annealed states were measured and the corresponding microstructures were observed. In both as-cast and as-solution states, thermal/electrical conductivities of the six groups of Mg alloys decreased with composition. Effects of solution treatment and annealing on thermal/electrical conductivities of the as-cast samples were also investigated and discussed. Moreover, the specific thermal/electrical resistivity (thermal/electrical resistivity increment of the alloy derived from one atom addition) of the solute elements for Mg alloys was drawn as follows, Zn < Al < Ca < Sn < Mn < Zr. Atomic volume difference of the solute elements with Mg atom (ΔV/V _Mg), valency, and configuration of extra-nuclear electron of the solute were believed as the main reasons for the differences.     

Time integration for spherical acoustic finite–infinite element models

In this paper, we analyse the numerical time integration of models of exterior acoustics. The major challenge lies in the instabilities that may arise from the infinite elements. In this paper we consider the special case of spherical infinite elements formulations, which have shown their relevance for industrial applications. We propose a method that combines Crank–Nicholson's method with a filtering step by the backward Euler method. The paper is illustrated with an example relevant to industry. Copyright © 2005 John Wiley & Sons, Ltd.     

Experiments on two immiscible fluids in spherical Couette flow

This paper deals with the experimental instabilities analysis of spherical Couette flow. We consider the flow of two immiscible fluids superimposed between concentric spheres when the outer sphere is fixed and the inner one rotates. The working fluids have rather different viscosities and thus different Reynolds numbers. The obtained results are compared with a reference case of filled gap using one fluid (Γ _max = 20). Experiments are performed for different aspect ratio values, and Laser photometric technique is used for visualization. Our analysis is mainly focused on the type of instabilities and their relationship with the laminar-turbulent transition regime. We intend to explore the combined effects of the aspect ratio and the interaction between the two superposed fluids on the appearance of different instability evolutions. The evolution of the phase velocity for different aspect ratio of heavy fluid Γ _HF = H _HF/d is presented. The immiscible fluids are separated by a liquid–liquid interface (water–oil). In order to control instability occurrence, Taylor number variation is presented versus aspect ratio. Instability phenomena are found to be the same as for the nominal case for large heavy fluid aspect ratios. The first equatorial symmetry breaking of the flow is observed for a critical value Γ _c  = 13 where the Taylor vortex flow is introduced with three stationary cells. For the same aspect ratio, the interaction of the immiscible fluids leads to the appearance of gravitational waves near the equatorial zone. A surface cell, starting before the appearance of Taylor vortices, is detected in the light fluid for low aspect ratios. This cell of Ekman type has not been observed before, to our best knowledge, in spherical Couette flow.     

Synthesis and characterization of Fe–B nanoparticles for potential magnetic applications

The crystallization and structure of Fe–B nanoparticles (NPs) of different sizes formed in a single process by gas aggregation from Fe₈₀B₂₀ targets were analyzed by transmission electron microscopy. It is concluded that all NPs are covered by an amorphous Fe–B shell while the crystal structure of the NPs core depends on their size. Large NPs with diameters ≥30 nm are monocrystalline tetragonal Fe₃B, small diameter NPs (≤20 nm) are completely amorphous whereas in middle size NPs, with diameters between 20 and 30 nm, difference Fe–B phases (tetragonal Fe₃B and orthorhombic FeB) together with defaulted areas are observed. This work opens new possibilities to produce Fe–B NPs tailoring their magnetic properties by controlling their size and composition.