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排序方式: 共有3021条查询结果,搜索用时 15 毫秒
91.
Robert E. Morris Bruce H. Black Clark S. Mitchell 《Petroleum Science and Technology》1994,12(7):1003-1018
A critical aspect in the assessment of thermal and storage stability of jet fuels is the measurement of hydroperoxide concentrations. The accepted procedure for this determination employs manual titration with standard thiosulfate using a visually detected color change to detect the endpoint. In many fuels, particularly when stressed, intense coloration of the fuel prevents accurate visual endpoint detection. This problem can be overcome by using a potentiometric method of endpoint detection with an automatic titrator. These two techniques are shown to provide identical results. The method also specifies the use of CFC-113 (Freon TF) as the titration solvent. Since CFC-113 will not be available in the future, several other solvents have been examined. Isopropanol and pure hydrocarbons show promise as suitable replacements. 相似文献
92.
Carolynn Reference to Black Akintola Reference to Akintoye Eamon Reference to Fitzgerald 《International Journal of Project Management》2000,18(6):423
Partnering is increasingly being used on construction projects. Partnering involves the parties to a construction project working together in an environment of trust and openness to realise the project efficiently and without conflict. Using a UK-wide postal questionnaire survey, the opinions of different types of organisation — consultants, contractors, and clients were assessed in relation to the success factors and benefits of partnering. The study shows that UK contractors and clients are more positive about partnering than consultants. The research also indicates that certain requirements must be met if partnering is to succeed. In particular, trust, communication, commitment, a clear understanding of roles, consistency and a flexible attitude are necessary. It is recognised that nothing will change without considerable effort from all parties. Respondents believe that partnering can bring significant benefits, including fewer adversarial relationships and increased end-customer satisfaction, to the construction industry if all parties involved in a project strive for its success. 相似文献
93.
Richard Lee Tom Beresford John Houser Amin Tadj Alda Black Marta Guerra Animations James Juricevich Parke Macdowell Dane Asmussen Laura Williams Peter Sprowls Noora Al Musallam Tammy Teng Wesley Hiatt John Mars Mazyar Kahali 《世界建筑导报》2018,(2)
正多伦多大学丹尼尔斯建筑、景观和设计学院的设计采用了分期的方法,包括修复和扩建以前称为知识学院的标志性建筑,将现有建筑物改造成与教学和需求更相关的框架体系。这个十九世纪遗址的总体规划是通过对预期用途模式和场地生态的分析而制定的,目的是重新定位校园西南角与安大略湖的轴线,并为学院创造新的特性。丹尼尔斯建筑、景观和设计学院需要一个可持续发展的新型工 相似文献
94.
Stability of wood fast pyrolysis oil 总被引:6,自引:0,他引:6
This study evaluates the effects of storage conditions on physical and chemical properties of biomass fast pyrolysis oils exposed to elevated temperatures over extended periods of time. It was performed on oak pyrolysis oil generated in the NREL vortex reactor. Oil samples were stored at three temperatures: 37, 60 and 90°C in glass vessels. Properties of the oils were measured after hours of storage at 90°C, and after days or weeks at lower temperatures. Chemical changes in the oils were measured using GPC (molecular weight distribution) and FTIR spectroscopy. The oil remained a single phase throughout the studied conditions. Its pH was not affected by storage. The water content, viscosity and molecular weight of the oil increased with the time and temperature of storage. First-order reaction kinetics were successfully used to predict changes in molecular weight of the stored oil. FTIR provided evidence that etherification or esterification are mechanisms for condensation of the oil during storage. 相似文献
95.
Local instantaneous heat-transfer coefficients were measured for free convection from an isothermal cylinder vibrating sinusoidally in a horizontal plane. The results show that the heat-transfer coefficient is strongly dependent upon the ratio of amplitude of vibration to cylinder diameter, . For values of less than approximately 0·25, a critical vibration intensity was observed below which vibration caused only small increases in the heat-transfer rate; however, at greater than 0·25, the critical vibrational intensity did not appear to exist because the heat transfer from the cylinder increased as soon as the vibrational speed increased from zero. A correlation of the data is presented which predicts the increase in average heat transfer from the cylinder to air above the free convective rate.The correlation also applies to data for much larger vibrational intensities. 相似文献
96.
W.Z. Black 《Fire Safety Journal》2010,45(6-8):337-348
A differential computer model specifically designed to quantify smoke movement during a fire in a high-rise structure is described. The basic conservation equations are transformed into a computer code which can be used to determine the paths that smoke will take during a fire. The program is a tool for fire protection engineers to design a smoke management plan with the ultimate goal of improving occupant safety in the event of a fire. The computer code is based on a modified and improved differential smoke control model for the conditions in the floor spaces, stairwells and elevator shafts and it considers a complete set of variables that influence the motion of smoke throughout the building. Program output suggests ways to alter the pressure distribution within the building by using air handling equipment, so that occupants will have smoke-free areas on the floors and inside of the fire escape stairwells. Results for several example cases are provided, and the results are used to illustrate how smoke movement can be managed in order to mitigate dangerous conditions within the building. 相似文献
97.
Kiser Laurel J.; Medoff Deborah; Black Maureen M.; Nurse Winona; Fiese Barbara H. 《Canadian Metallurgical Quarterly》2010,24(1):92
Studies outlining the protective functions of shared family meals suggest that helping families experience successful meals is an important goal. Measuring the effectiveness of family mealtime interventions necessitates the ability to quantify both the frequency and context of shared mealtimes. This article introduces a new instrument, the Family Mealtime Q-Sort, describes its development, and presents preliminary data about its psychometric properties. Data from initial evaluation of the Family Mealtime Q-Sort using family mealtime videos (N = 51) demonstrate acceptable interrater reliability, promising validity, and the ability to compare family mealtimes to an independently derived, culturally appropriate standard. The results suggest that the Q-sort adequately measures important dimensions of a successful mealtime including a positive atmosphere, making use of the shared time to engage in meaningful conversation, and proceeding with a clear plan and minimal distractions. Further research on the tool is warranted. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
98.
Shuohui Chen Harriet Black Nembhard 《Quality and Reliability Engineering International》2011,27(4):451-464
Profile monitoring is an important and rapidly emerging area of statistical process control. In many industries, the quality of processes or products can be characterized by a profile that describes a relationship or a function between a response variable and one or more independent variables. A change in the profile relationship can indicate a change in the quality characteristic of the process or product and, therefore, needs to be monitored for control purposes. We propose a high‐dimensional (HD) control chart approach for profile monitoring that is based on the adaptive Neyman test statistic for the coefficients of discrete Fourier transform of profiles. We investigate both linear and nonlinear profiles, and we study the robustness of the HD control chart for monitoring profiles with stationary noise. We apply our control chart to monitor the process of nonlinear woodboard vertical density profile data of Walker and Wright (J. Qual. Technol. 2002; 34:118–129) and compare the results with those presented in Williams et al. (Qual. Reliab. Eng. Int. 2007; to appear). Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
99.
George W. Mushrush John M. Watkins Robert N. Hazlett Dennis R. Hardy Bruce H. Black 《Petroleum Science and Technology》2013,31(7):753-767
ABSTRACT Instability problems in both shale and petroleum derived middle distillate jet fuels have been correlated with the presence of peroxidic species. Although a good body of knowledge exists concerning the formation of peroxides in the liquid phase, relatively little is known about the reaction/ decomposition pathways available when other functional groups are present, since sulfur is the most abundant heteroatam present in jet fuels, the reaction of t-butyl hydroperoxide (tBKP) and/or oxygen with thiophenol in the presence of the active olefin, styrene, was examined in deaerated benzene at 120°C. The complex product mixture was analyzed by combined capillary column GC/MS. Major products included acetone, t-butanol and isdbutylene from the tBHP. Thiophenol and styrene combined to form addition products. Phenyl disulfide was observed from the thiophenol. The results indicated that although the product slate was complex, it was possible to explain the product mix in terms of a few competing reactions. 相似文献
100.
This article briefly explains the technique of induction heating as applied to thick-walled super duplex pipe. It describes
the theoretical temperature distribution which might be expected through the wall of such a pipe. An experiment is outlined
that uses thermocouples to determine the actual temperature profiles within the wall of induction-heated pipe. The results
of the experiment are given, and identifiable trends are discussed. A second experiment is then performed where the pipe is
subjected to induction bending, and again the results are explained and discussed. Apparent discrepancies between theoretical
and actual temperature profiles are then explained. 相似文献