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171.
This study investigated the role of age, marital status, gender, nationality, educational background and monthly income in drivers' comprehension of traffic signs. The populations sampled here were from five Arabian Gulf Countries. A total of 28 symbolic warning and regulatory signs were investigated. A questionnaire specially prepared to collect the necessary data was distributed to over 9000 drivers in the five countries; 4774 responded (53%). The results indicated substantial problems with the level of comprehension among the drivers about the traffic signs. The percentages of drivers who correctly identified the regulatory signs and warning signs were around 55 and 56%, respectively. Age, gender, education and income played major roles in determining drivers' comprehension of signs, whereas marital status showed no significant effect. Drivers who are young, female, those with lower levels of education or lower incomes understand the signs significantly worse than drivers who are older, male, with higher levels of education or higher incomes. Drivers from Europe and USA are significantly better than Asian and Arab drivers. These findings are believed to be important for the designers of road signs for international applications. 相似文献
172.
Gap junctions are collections of intercellular membrane channels that allow adjacent cells to share small molecules (< 1 kDa). Gap junction channels are composed of connexins, a homologous family of more than 20 proteins. In developing follicles, gap junctions couple the growing oocyte and its surrounding follicle cells into a functional syncytium. This review summarizes evidence on the expression of various connexins in developing follicles and the likely roles that some of the connexins play, on the basis of findings from gene targeting experiments in mice. Gap junctions between cumulus cells contain predominantly connexin43, and this connexin has also been detected using immunoelectron microscopy in a small minority of gap junctions at the oocyte surface. The importance of connexin43 for granulosa cell function is demonstrated by the fact that follicles lacking this connexin arrest in early preantral stages and produce incompetent oocytes. Connexin37 appears to be the only connexin contributed by oocytes to the gap junctions coupling them with granulosa cells, and loss of this connexin interferes with the development of antral follicles. The expression of multiple connexins in developing follicles is thus likely to reflect the multiple functions served by gap junctional communication in folliculogenesis. 相似文献
173.
S. Abdul Jawad 《Polymer International》1994,33(4):373-376
Dynamic tensile and shear moduli measurements have been carried out on highly oriented thermotropic liquid crystalline copolymers formed by random copolymerization of 2-hydroxy-6-naphthoic acid, terephthalic acid and p-aminophenol. This liquid crystalline copolymer is known as HNATA. Application of the aggregate model of units of structure gives rise to an estimation of the orientation angle θ = 5° and a chain modulus Ec = 230 GPa. The fall in tensile modulus with increasing temperature is related to two factors: a decrease in the intrinsic chain modulus and a reduction in the shear modulus. 相似文献
174.
The influences of pH, potential and C content on the steady-state dissolution of Fe have been examined in H2-saturated sulphate solutions. The Tafel slope, amounting to 60 mV/decade, is independent of pH or C content. The reaction shows a first-order dependence on pH. 相似文献
175.
AC conductivity of consolidated nanoparticles of NiO, having different average particle sizes (2.5 nm–17 nm) was measured in the temperature range 313 K to 413 K and over the frequency range 50 Hz to 3 MHz. The ac conductivity of the samples was found to be enhanced by six to eight orders of magnitude over that of NiO single crystals reported in the literature. This large enhancement in conductivity is attributed to the high density of Ni2+ vacancies in the nanoparticles. The variation of ac conductivity with frequency of the applied signal and temperature is discussed on the basis of the Correlated Barrier Hopping (CBH) Model. The observed spread in activation energy and slope of the log ac Vs log plots is attributed to the distribution of the charge carrier hopping distance and localization energies in the nanoparticle samples. The effect of the interfacial region on the electrical conductivity of the samples is analyzed by taking into account the contributions due to grain boundaries and triple junctions. The observed variation of measured ac conductivity with average particle size is semi-quantitatively explained based on the reasoning that the role of the triple junctions is to reduce the conductivity. 相似文献
176.
The experimental study of the laser beam parameters of the pulse repetitive RF-excited diffusion cooled waveguide CO2 laser are presented. The measurements are carried out for the pumping pulse duration of 100 μs and pulse repetitive rates 5 - 14 kHz. The average power density delivered to the active medium is 76 W/cm^3. Three types of the pulses, namely the square, the sine and the triangular ones have been applied at the input as pumping pulses and their effects on the output power and the delay time have been studied. The output power of the radiation versus input power, pressure of the laser gas mixture and modulation frequency has been investigated. The results indicate that the output peak power for the three types of pulses increases with increase of the pressure of the laser gas mixture and with the input power where as it decreases with the repetition frequency. The delay time of the output pulse decreases with the increase of the repetition frequency and input power, where as it increases with the increase of the pressure of the laser gas mixture. The behavior of the output power and the delay time with duty cycle for square pulse has also been investigated. 相似文献
177.
Abdul Manaf Hashim Seiya Kasai Kouichi Iizuka Tamotsu Hashizume Hideki Hasegawa 《Microelectronics Journal》2007,38(12):1268-1272
Theoretical analysis of potential distribution in the interdigital-gated high electron mobility transistor (HEMT) plasma wave device was carried out. The dc I–V characteristics of capacitively coupled interdigital structure showed that uniformity of electric field under the interdigital gates was improved compared to the dc-connected interdigital gate structure. Admittance measurements of capacitively coupled interdigital gate structure in the microwave region of 10–40 GHz showed the conductance modulation by drain–source voltage. These results indicate the existence of plasma wave interactions. 相似文献
178.
Wan Norlinda Roshana Mohd Nawi Sharifah Rafidah Wan Alwi Zainuddin Abdul Manan Jiří Jaromír Klemeš 《Clean Technologies and Environmental Policy》2016,18(6):1769-1777
There has been growing interests to reduce the environmental impact caused by greenhouse gas emissions from process plants through various energy conservation strategies. CO2 emissions are closely linked to energy generation, conversion, transmission and utilisation. Various studies on the design of energy-efficient processes, optimal mix of renewable energy and hybrid power system are driven to reduce reliance on fossil fuel as well as CO2 emissions reduction. This paper presents a systematic technique in the form of graphical visualisation tool for cost-effective CO2 emission reduction strategies in industry. The methodology is performed in four steps. The first step involves calculating the energy consumption of a process plant. This is followed by identification of potential strategies to reduce CO2 emissions using the CO2 management hierarchy as a guide. In the third step, the development of “Investment” versus “CO2 Reduction” (ICO2) plot is constructed to measure the optimal CO2 emission reductions achieved from the implementation of possible CO2 reduction strategies. The Systematic Hierarchical Approach for Resilient Process Screening (Wan Alwi and Manan in AIChE J 11:3981–3988, 2006) method is used in the fourth step via substitution or partial implementation of the various CO2 reduction options in order to meet the cost-effective emission reduction within the desired investment limit or payback period (PP). An illustrative case study on a palm oil refinery plant has been used to demonstrate the implementation of the method in reduction of CO2 emissions. The developed graphical tool provides an insight-based approach for systematic CO2 emission reduction in the palm oil refinery considering both heat and power energy sources. Result shows that 31.2 % reduction in CO2 emissions can be achieved with an investment of USD 38,212 and PP of 10 months based on the present energy prices in Malaysia. 相似文献
179.
Hameed Hussain Saif Ur Rehman Malik Abdul Hameed Samee Ullah Khan Gage Bickler Nasro Min-Allah Muhammad Bilal Qureshi Limin Zhang Wang Yongji Nasir Ghani Joanna Kolodziej Albert Y. Zomaya Cheng-Zhong Xu Pavan Balaji Abhinav Vishnu Fredric Pinel Johnatan E. Pecero Dzmitry Kliazovich Pascal Bouvry Hongxiang Li Lizhe Wang Dan Chen Ammar Rayes 《Parallel Computing》2013
An efficient resource allocation is a fundamental requirement in high performance computing (HPC) systems. Many projects are dedicated to large-scale distributed computing systems that have designed and developed resource allocation mechanisms with a variety of architectures and services. In our study, through analysis, a comprehensive survey for describing resource allocation in various HPCs is reported. The aim of the work is to aggregate under a joint framework, the existing solutions for HPC to provide a thorough analysis and characteristics of the resource management and allocation strategies. Resource allocation mechanisms and strategies play a vital role towards the performance improvement of all the HPCs classifications. Therefore, a comprehensive discussion of widely used resource allocation strategies deployed in HPC environment is required, which is one of the motivations of this survey. Moreover, we have classified the HPC systems into three broad categories, namely: (a) cluster, (b) grid, and (c) cloud systems and define the characteristics of each class by extracting sets of common attributes. All of the aforementioned systems are cataloged into pure software and hybrid/hardware solutions. The system classification is used to identify approaches followed by the implementation of existing resource allocation strategies that are widely presented in the literature. 相似文献
180.
Resource discovery is one of the most important services that significantly affects the efficiency of grid computing systems. The inherent dynamic and large-scale characteristics of grid environments make their resource discovery a challenging task. In recent years, different approaches have been proposed for resource discovery, attempting to tackle the challenges of grid environments and improve the efficiency. Being aware of these challenges and approaches is worthwhile in order to choose an appropriate approach according to the application in different organizations. This study reviews the most important factors that should be considered and challenges to be tackled in order to develop an efficient grid resource discovery system. 相似文献