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101.
Z. G. Liu A. Kashef G. Crampton G. Lougheed Y. Ko G. Hadjisophocleous Kathleen H. Almand 《Fire Technology》2010,46(3):697-718
Fire detection systems play a crucial role in ensuring safe evacuation and firefighting operations in road tunnels, but information
on the performance of these systems in tunnels has been limited and guidelines for their application in tunnel environments
are not fully developed. Recently, the National Research Council of Canada (NRC) and the Fire Protection Research Foundation
completed a 2-year international research project, with the support of private- and public-sector organizations, to determine
some of the strengths and weaknesses of the various types of fire detection systems and the factors that can affect their
performance in tunnel environments. The project included both laboratory and field fire tests combined with computer modeling
studies. Although this research was conducted on road tunnels, the findings should apply to other tunnels, such as those used
in subway systems. As part of the project, the NRC conducted two series of tests in the Carleton University-NRC tunnel facility
to investigate the performance of detection systems under minimal and longitudinal airflow conditions. In addition, NRC conducted
tests in the Carré-Viger Tunnel in Montréal, as well as a computer modeling study. The project studied nine fire detection
systems that covered five types of currently available technologies. The performance of the detection systems, including response
times and ability to locate and monitor a fire in the tunnel and the effect of the tunnel environment, were evaluated under
the same conditions. This article provides an overview of the findings of the project. Fire detectors, fire scenarios and
test protocols used in the test program are described. A summary of the research results of the full-scale fire tests conducted
in a laboratory tunnel facility and in an operating road tunnel as well as of the computer modeling activities is reported. 相似文献
102.
An innovative approach to electro-oxidation of dopamine on titanium dioxide nanotubes electrode modified by gold particles 总被引:1,自引:1,他引:0
Mirghasem Hosseini Mohamad Mohsen Momeni Masoud Faraji 《Journal of Applied Electrochemistry》2010,40(7):1421-1427
Au/TiO2/Ti electrodes were prepared by galvanic deposition of gold particles from an acidic bath containing KAu(CN)2 in the presence of a citrate buffer onto TiO2 nanotubes layer on titanium substrates. Titanium oxide nanotubes were fabricated by anodizing titanium foil in a DMSO fluoride-containing electrolyte. The morphology and surface characteristics of Au/TiO2/Ti electrodes were investigated using scanning electron microscopy and energy-dispersive X-ray, respectively. The results indicated that gold particles were homogeneously deposited on the surface of TiO2 nanotubes. The nanotubular TiO2 layers consist of individual tubes of about 40–80 nm diameters. The electro-catalytic behavior of Au/TiO2/Ti electrodes for the dopamine electro-oxidation was studied by cyclic voltammetry and differential pulse voltammetry. The results showed that Au/TiO2/Ti electrodes exhibit a considerably higher electro-catalytic activity toward the oxidation of dopamine. The catalytic oxidation peak current showed a linear dependence on dopamine concentration and a linear calibration curve was obtained in the concentration range of 0.5–2.5 mM of dopamine. 相似文献
103.
M. B. Abu Bakar Z. A. Mohd Ishak R. Mat Taib H. D. Rozman S. Mohamad Jani 《应用聚合物科学杂志》2010,116(5):2714-2722
Polypropylene (PP) composites filled with wood flour (WF) were prepared with a twin‐screw extruder and an injection‐molding machine. Three types of ecologically friendly flame retardants (FRs) based on ammonium polyphosphate were used to improve the FR properties of the composites. The flame retardancy of the PP/WF composites was characterized with thermogravimetric analysis (TGA), vertical burn testing (UL94‐V), and limiting oxygen index (LOI) measurements. The TGA data showed that all three types of FRs could enhance the thermal stability of the PP/WF/FR systems at high temperatures and effectively increase the char residue formation. The FRs could effectively reduce the flammability of the PP/WF/FR composites by achieving V‐0 UL94‐V classification. The increased LOI also showed that the flammability of the PP/WF/FR composites was reduced with the addition of FRs. The mechanical property study revealed that, with the incorporation of FRs, the tensile strength and flexural strength were decreased, but the tensile and flexural moduli were increased in all cases. The presence of maleic anhydride grafted polypropylene (MAPP) resulted in an improvement of the filler–matrix bonding between the WF/intumescent FR and PP, and this consequently enhanced the overall mechanical properties of the composites. Morphological studies carried out with scanning electron microscopy revealed clear evidence that the adhesion at the interfacial region was enhanced with the addition of MAPP to the PP/WF/FR composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
104.
Wardah Fatimah Mohammad Yusoff Elias Salleh Nor Mariah Adam Abdul Razak Sapian Mohamad Yusof Sulaiman 《Building and Environment》2010
In the hot and humid climate, stack ventilation is inefficient due to small temperature difference between the inside and outside of naturally ventilated buildings. Hence, solar induced ventilation is a feasible alternative in enhancing the stack ventilation. This paper aims to investigate the effectiveness of a proposed solar induced ventilation strategy, which combines a roof solar collector and a vertical stack, in enhancing the stack ventilation performance in the hot and humid climate. The methodology selected for the investigation is physical experimental modelling which was carried out in the actual environment. The results are presented and discussed in terms of two performance variables: air temperature and air velocity. The findings indicate that the proposed strategy is able to enhance the stack ventilation, both in semi-clear sky and overcast sky conditions. The highest air temperature difference between the air inside the stack and the ambient air (Ti−To) is achieved in the semi-clear sky condition, which is about 9.9 °C (45.8 °C–35.9 °C). Meanwhile, in the overcast sky condition, the highest air temperature difference (Ti−To) is 6.2 °C (39.3 °C–33.1 °C). The experimental results also indicate good agreement with the theoretical results for the glass temperature, the air temperature in the roof solar collector’s channel and the absorber temperature. The findings also show that wind has significant effect to the induced air velocity by the proposed strategy. 相似文献
105.
Robert Chebli Mohamad Sawan Kamal El-Sankary Yvon Savaria 《Analog Integrated Circuits and Signal Processing》2010,62(2):223-235
An efficient low power protection scheme for thin gate oxide of high voltage (HV) DMOS transistor is presented. To prevent gate-oxide breakdown and protect HV transistor, the voltage controlling its gate must be within 5 V from the HV supply. Thus signals from the low voltage domain must be level shifted to control the gate of this transistor. Usually this level shifting involves complex circuits that reduce the speed besides requiring of large power and area. In this paper, a simple and efficient protection technique for gate-oxide breakdown is achieved by connecting a capacitor divider structure to the floating-gate node of HV transistor to increase its effective gate oxide thickness. Several HV circuits, including: positive and negative HV doublers and level-up shifters suitable for ultrasound sensing systems are built successfully around the proposed technique. These circuits were implemented with 0.8 μm CMOS/DMOS HV DALSA process. Simulation and experimental results prove the good functionality of the designed HV circuits using the proposed protection technique for voltages up to 200 V. 相似文献
106.
Dechlorination of polychlorinated biphenyls in industrial transformer oil by radiolytic and photolytic methods 总被引:3,自引:0,他引:3
Jones CG Silverman J Al-Sheikhly M Neta P Poster DL 《Environmental science & technology》2003,37(24):5773-5777
Used electrical transformer oils containing low or high concentrations of polychlorinated biphenyls (PCBs) were treated using electron, gamma, and ultraviolet radiation, and the conditions for complete dechlorination were developed. Dechlorination was determined by analysis of the inorganic chloride formed and the concentrations of remaining PCBs. Transformer oil containing approximately 95 microg g(-1) PCB (approximately 3.5 mmol L(-1) Cl) is completely dechlorinated by irradiation with 600 kGy after the addition of 10% triethylamine (TEA). Transformer oil containing >800,000 microg g(-1) PCB (17.7 mol L(-1) Cl) requires an additional solvent to prevent solidification. When this oil is diluted with 2-propanol (2-PrOH) and TEA (v/v/v, 1/79/20), complete dechlorination is achieved with a dose of 2500 kGy. Ultraviolet photolysis of the same oil/2-PrOH/TEA solutions led to 90% dechlorination after exposure for 120 h in our experimental setup. Such yields were obtained by radiolysis with a dose of 2000 kGy (300 h in our Gammacell). Replacing TEA with KOH in 2-PrOH solutions greatly increases the yield of dechlorination in both the radiolytic and the photolytic experiments, demonstrating that a chain reaction plays a role in both of these treatment methods and suggesting that both methods deserve further consideration for large-scale application. 相似文献
107.
Abolfazl Shoja Mohamad Ali Adabi Masoud Ahmadnia Jamal Zamani 《Propellants, Explosives, Pyrotechnics》2014,39(4):574-579
In most blast loading structure analyses, it is assumed that the load acts uniformly on a target area. For the rationable design, it is useful to have a quantitative criterion to determine at which maximum distance the standoff can be placed to assume a uniform pressure distribution. Surprisingly, no standard criterion was found in the literature and the effect of blast wave clearing was not considered as well. In this paper, pressure histories applied on structures are calculated considering the non‐uniform loading characteristic as well as pressure relief from the edges. Additionally, the effects of various parameters on uniformity of impulse distribution are investigated. The results have shown that the effect of pressure relief on impulse uniformity is very important, especially when the blast wave is attenuated. This phenomenon leads an optimum distance at which impulse distribution is the most uniform. 相似文献
108.
Gillian R. Hayes Sen Hirano Gabriela Marcu Mohamad Monibi David H. Nguyen Michael Yeganyan 《Personal and Ubiquitous Computing》2010,14(7):663-680
Interventions to support children with autism often include the use of visual supports, which are cognitive tools to enable learning and the production of language. Although visual supports are effective in helping to diminish many of the challenges of autism, they are difficult and time-consuming to create, distribute, and use. In this paper, we present the results of a qualitative study focused on uncovering design guidelines for interactive visual supports that would address the many challenges inherent to current tools and practices. We present three prototype systems that address these design challenges with the use of large group displays, mobile personal devices, and personal recording technologies. We also describe the interventions associated with these prototypes along with the results from two focus group discussions around the interventions. We present further design guidance for visual supports and discuss tensions inherent to their design. 相似文献
109.
Juan Xie Yawen He Xian Li Ming Duan Junlei Tang Yingying Wang Mohamad Chamas Hu Wang 《Journal of Materials Science: Materials in Electronics》2017,28(20):14981-14987
Strontium titanate (STO) with shape of nanosheet, polyhedron and nanosphere is prepared by one-pot solvothermal method using ethanolamine (EA), diethanolamine (DA) and ethylene glycol (EG), respectively. Upon the different crystalline size and morphology of STO, effect of solvents on nucleation and growth is discussed. In this case, energy band and flat band potential of samples are measured by UV–Vis diffuser reflectance (DRS) and Mott-Schottky (MS). Results show narrow energy band (Eg) 2.68, 2.87 and 3.17 eV of as-synthesized pure STOs (EA-STO, DA-STO and EG-STO) compared with empirical STO. Simultaneously, valence band shows 0.55, 1.80 and 2.21 eV respectively. Rhodamine B (RhB) and methyle orange (MO) are selected as anionic and cationic target contaminants. Correlation of photodegradation performance and valence band is depicted. 相似文献