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161.
M.H.F.M. Barros R.A.F. Martins A.F.M. Barros 《Structural and Multidisciplinary Optimization》2005,30(3):236-242
A model for the optimal design of rectangular reinforced concrete sections is presented considering the stress–strain diagrams described in EC2-2001 and MC90. The following expressions are developed: economic bending moment; optimal area of steel and optimal steel ratio between upper and lower steel. All the expressions are in nondimensional form. The present model is applied to four different classes of concrete described in MC90. It is concluded that in nondimensional form the equations are nearly coincident for both singly and doubly reinforcement. It is also concluded that the ultimate strain for concrete in the compression zone, εcm, lies between the strain for peak stress εc1 and the ultimate strain εcu. This result is relevant once that the maximum moment is obtained for this value, and not the value εcu, as defined in EC2-2001. Cost optimization is implemented in the code and compared with other optimum models based on the ultimate design of ACI. 相似文献
162.
P von Hafe C Lopes PB Fernando E Ramos MJ Andrade R Coelho MJ Maciel H Barros 《Canadian Metallurgical Quarterly》1997,16(9):695-702, 664
A case-control study of coronary heart disease (CHD) was conducted in Oporto, Portugal. The cases series consisted of 100 consecutive patients with first time acute myocardial infarction who were admitted to the Coronary and Intermediate Care Units of a major teaching hospital. The community controls were 198 individuals without evidence of CHD by the Rose questionnaire and electrocardiography, selected by random digit dialing, with a participation rate of 70%. Data was collected by trained interviewers using a structured questionnaire and blood samples were obtained for selected laboratory data. The main analysis was made through unconditional logistic regression with calculations of odds ratios (OR). Age, OR: 1.5 (95% CI: 0.8-2.9), male gender, OR: 6.7 (3.6-12.3), family history of premature CHD, OR: 2.4 (1.4-4.3), diabetes, OR: 3.4 (1.6-7.4), antecedents of hypertension, OR:1.9 (1.1-3.1), history of high cholesterol levels, OR: 2.3 (1.4-3.9), high levels of physical activity, OR: 2.0 (0.9-4.1) and tobacco smoking, OR: 8.3 (3.8-18.5) were significant risk factors of acute myocardial infarction. After controlling for demographic variables and for the mutual confounding effects of the risk factors, the investigated factors that remained significantly associated with the risk of developing acute myocardial infarction were male gender, OR: 17.3 (4.8-62.3), family history of CHD, OR: 3.6 (1.4-9.6), diabetes, OR: 4.2 (1.0-18.1), high cholesterol levels OR: 2.7 (1.2-6.1) and smoking habits, OR: 7.7 (1.8-32.4). A negative association with high education levels was significant after controlling for all the variables, OR: 0.01 (0.01-0.5). 相似文献
163.
Boone Kyle Brauer; Lesser Ira M.; Miller Bruce L.; Wohl Marcy; Berman Nancy; Lee Alison; Palmer Barton; Back Carla 《Canadian Metallurgical Quarterly》1995,9(3):390
Neuropsychological evaluation of 73 older healthy, unmedicated outpatients with major depression and 110 controls suggested that relatively distinct cognitive profiles may correspond to the presence vs. severity of depression. Specifically, the presence of depression was associated with subtle weaknesses in visual memory and nonverbal intelligence, with sparing of verbal skills (verbal intelligence, language, and verbal memory), constructional ability, attention, information processing speed, and executive functions. In contrast, increasing severity of depression was associated with mild weaknesses, primarily in information-processing speed and executive skills, but was essentially unrelated to memory (verbal or visual), intelligence, language skills, constructional ability, or basic attention. Findings are discussed in terms of a possible state vs. trait model of depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
164.
165.
Wills Thomas Ashby; Yaeger Alison M.; Sandy James M. 《Canadian Metallurgical Quarterly》2003,17(1):24
This research examined the hypothesis that religiosity buffers the impact of life stress on adolescent substance use. Data were from a sample of 1,182 participants surveyed on 4 occasions between 7th grade (mean age = 12.4 years) and 10th grade. Religiosity was indexed by Jessor's Value on Religion Scale (R. Jessor & S. L. Jessor, 1977). Zero-order correlations showed religiosity inversely related to alcohol, tobacco, and marijuana use. Significant Life Events×Religiosity buffer interactions were found in cross-sectional analyses for tobacco, alcohol, and marijuana use. A latent growth analysis showed that religiosity reduced the impact of life stress on initial level of substance use and on rate of growth in substance use over time. Implications for further research on religiosity and substance use are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
166.
Although there is substantial evidence that 30-mo-old children can reason about other people's desires, little is known about the developmental antecedents of this ability. A food-request procedure was devised to explore this understanding in 14- and 18-mo-olds. Children observed an experimenter expressing disgust as she tasted 1 type of food and happiness as she tasted another type of food. They were then required to predict which food the experimenter would subsequently desire. The 14-mo-olds responded egocentrically, offering whichever food they themselves preferred. However, 18-mo-olds correctly inferred that the experimenter wanted the food associated with her prior positive affect. They were able to make this inference even when the experimenter's desires differed from their own. These data constitute the first empirical evidence that 18-mo-olds are able to engage in some form of desire reasoning. Children not only inferred that another person held a desire, but also recognized how desires are related to emotions and understood something about the subjectivity of these desires. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
167.
Cristiano Araujo Millena Gomes Edna Barros Sandro Rigo Rodolfo Azevedo Guido Araujo 《Design Automation for Embedded Systems》2005,10(4):253-283
This paper[3.5pc] presents the Platform Designer (PD) framework, a set of SystemC based tools that provide support for modeling,
simulation and analysis of multiprocessor SoC platforms (MPSoC), at different abstraction levels. PD provides mechanisms for
interconnection specification, process synchronization and communication, thus allowing the modeling of a complete platform,
in a unified environment. To do that it uses an extension of the ArchC ADL and acsys, a tool that enables the automatic generation
of a SystemC simulator of the platform. The main advantages of this approach are twofold. First, designers have more flexibility
since they can integrate and configure different processors to the platform, using a single environment. Second, it enables
a faster design space exploration, given that it automatically generates SystemC simulators of whole platforms at distinct
abstraction levels. A number of platform variations can be tried out with minor design changes, thus reducing design time.
Experimental results show the suitability of the platform simulator for design space exploration. Real applications (with
medium complexity) run in the platform in few minutes. Combined with the facility to generate platforms with minor changes,
this feature allows an improvement of the design space exploration. 相似文献
168.
169.
All-fiber active add-drop wavelength router 总被引:4,自引:0,他引:4
G. Nykolak M.R.X. de Barros T.N. Nielsen L. Eskildsen 《Photonics Technology Letters, IEEE》1997,9(5):605-606
We describe a fiber Bragg grating Mach-Zehnder interferometer (FBG-MZI) which utilizes active phase control. The active FBG-MZI is operated as a wavelength router, where the grating-selected wavelength channel can be actively routed. We believe this is the first demonstration of an all fibre FBG-MZI wavelength router. 相似文献
170.
A ground heat exchanger system is applied as a way to improve the heat recovery ratio in a project using industrial waste heat recovery for district heating. In order to meet the requirements of industrial processes, the outlet water temperature of the system should be strictly controlled within a range, but the heat transfer power varies with the warming or cooling of the soil. An operation strategy named “block by block” is implemented and a corresponding model is established. In this strategy, the total area of the system is divided into several blocks. The water flows by a specific combination of blocks at any given time, ensuring the outlet water temperature is relatively stable. By simulation, it is concluded that the strategy is fit for the practice of industrial waste heat storage and extraction. 相似文献