This paper deals with physical and material modelling of a cooling tower–foundation–soil system. The physical modelling has been carried out using solid 20-noded isoparametric element to model the cooling tower, annular raft foundation and soil media. The cooling tower–foundation–soil system was analysed under vertical and lateral load generated due to self-weight and wind loads. The soil nonlinearity has been taken into consideration using hyperbolic nonlinear elastic constitutive law. The response of the structure has been investigated with respect to displacement and stresses. Moreover, an attempt has been made to study the effect of the linear and nonlinear interactive analyses compared with conventional analysis. It was seen that the interactive analysis of the cooling tower–foundation–soil media plays a major role in releasing the stresses in the cooling tower, particularly at the bottom ring beam. 相似文献
Oxidation of raw water with chlorine results in formation of trihalomethanes (THM) and haloacetic acids (HAA). Factors affecting their concentrations have been found to be organic matter type and concentration, pH, temperature, chlorine dose, contact time and bromide concentration, but the mechanisms of their formation are still under investigation. Within this scope, chlorination experiments have been conducted with water reservoirs from Terkos, Buyukcekmece and Omerli lakes, Istanbul, with different water quality regarding bromide concentration and organic matter content. The factors studied were pH, contact time, chlorine dose, and specific ultraviolet absorbance (SUVA). The determination of disinfection by-products (DBP) was carried out by gas chromatography techniques. Statistical analysis of the results was focused on the development of multiple regression models for predicting the concentrations of total THM and total HAA based on the use of pH, contact time, chlorine dose, and SUVA. The developed models provided satisfactory estimations of the concentrations of the DBP and the model regression coefficients of THM and HAA are 0.88 and 0.61, respectively. Further, the Durbin-Watson values confirm the reliability of the two models. The results indicate that under these experimental conditions which indicate the variations of pH, chlorine dosages, contact time, and SUVA values, the formation of THM and HAA in water can be described by the multiple linear regression technique. 相似文献
Using previously applied methods a survey of joint symptoms was undertaken among 4232 adults, evenly distributed between affluent and poor areas of Karachi, Pakistan. Only six cases of definite rheumatoid arthritis (RA) (1958 ARA criteria) were identified in the 245 persons who complained of joint problems of at least 4 weeks duration. The prevalence was 0.9 [confidence interval (CI) 0.21-3.61] and 1.98 (CI 0.55-5.1) per thousand in the poor and affluent districts, respectively. These were substantially less than prevalence rates reported in the West but were similar to figures derived from other developing countries. There was no obvious impact of current living standards on the findings. The relative paucity of older female subjects in both the affluent and poor communities may account at least in part for the low rates observed. The infrequency of rheumatoid nodules in Southern Asians with RA illustrates the difficulty of applying existing diagnostic criteria to this community. 相似文献
In this technical note, a thin circular plate resting on a two-parameter (Pasternak-type) foundation is studied under concentrated central and distributed loads. The governing equations of the plate are derived for static loading case considering the lift off (uplift) of the plate from the foundation. For the approximate solution, a Galerkin technique is adopted and the free vibration mode shapes of the completely free plate are chosen as the displacement functions. The technique yields a system of algebraic nonlinear equations, and its solution is accomplished by using an iterative method. The numerical results are obtained for evaluation of the behavior of the plate and then given comparatively in figures. Although in the case of a tensionless Winkler foundation, the lift off of the plate from the foundation takes place, when the displacement of plate is negative, while in case of the two-parameter foundation the lift off appears when the slopes of the foundation surface and that of the plate are not equal. 相似文献
PURPOSE: Gabapentin (GBP), lamotrigine (LTG), tiagabine (TGB), topiramate (TPM), vigabatrin (VGB), and zonisamide (ZNS) are all in use as "add-on" treatment for patients with refractory epilepsy. There have been no comparative randomized controlled trials allowing an evidence-based choice between these drugs. We report a series of meta-analyses of randomized placebo-controlled add-on trials in which these drugs have been tested in patients with partial epilepsy. This work provides an estimate of each drug's efficacy and tolerability compared with placebo. These estimates are compared across drugs to give broad estimates of comparative efficacy and tolerability. METHODS: Trial reports were found by searching Medline, by searching through journals by hand, and by contacting the pharmaceutical industry. The outcomes chosen were the proportion of patients who (a) have a > or = 50% reduction in seizure frequency (50% responders); (b) withdrew from the study (any reason); or (c) reported the following side effects: ataxia, dizziness, fatigue, nausea, or somnolence. Overall odds ratio (OR) with 95% confidence intervals (CIs; 50% responders) or 99% CIs; side effects) were calculated. RESULTS: Twenty-nine trials were included, representing 4,091 randomized patients. The ORs for 50% response (95% CI) were GBP, 2.29 (1.53-3.43); LTG, 2.32 (1.47-3.68); TGB, 3.03 (2.01-4.58); TPM, 4.07 (2.87-5.78); VGB, 3.67 (2.44-5.51); and ZNS, 2.7 (1.36-4.47). ORs for discontinuation were GBP, 1.36 (0.75-2.49); LTG, 1.19 (0.79-1.79); TGB, 1.81 (1.21-2.70); TPM, 2.56 (1.64-4.00); VGB, 2.58 (126-5.27); and ZNS, 4.23 (1.71-10.49). CONCLUSIONS: We have clear evidence that each of these drugs is better than placebo at preventing seizures. When results are compared across drugs, the confidence intervals overlap, and we have no conclusive evidence of differences in efficacy or tolerability. Despite this, the agent that appears most effective may be twice as effective as the agent that appears least effective, and the agent that appears most likely to cause discontinuation may be 4 times more likely to do so than the treatment that appears least likely to do so. Comparative randomized studies are needed further to evaluate these drugs. 相似文献
In this article, the Cattaneo–Christov heat flux model is implemented to study non-Fourier heat and mass transfer in the magnetohydrodynamic flow of an upper-convected Maxwell fluid over a permeable stretching sheet under a transverse constant magnetic field. Thermal radiation and chemical reaction effects are also considered. The nonlinear partial differential conservation equations for mass, momentum, energy and species conservation are transformed with appropriate similarity variables into a system of coupled, highly nonlinear ordinary differential equations with appropriate boundary conditions. Numerical solutions have been presented for the influence of elasticity parameter (α), magnetic parameter (M2), suction/injection parameter \((\lambda ),\) Prandtl number (Pr), conduction–radiation parameter (Rd), sheet stretching parameter (A), Schmidt number (Sc), chemical reaction parameter \(\left( {\gamma_{c} } \right)\), modified Deborah number with respect to relaxation time of heat flux (i.e., non-Fourier Deborah number) on velocity components, temperature and concentration profiles using the successive Taylor series linearization method (STSLM) utilizing Chebyshev interpolating polynomials and Gauss–Lobatto collocation. The effects of selected parameters on skin friction coefficient, Nusselt number and Sherwood number are also presented with the help of tables. Verification of the STSLM solutions is achieved with existing published results demonstrating close agreement. Further validation of skin friction coefficient, Nusselt number and Sherwood number values computed with STSLM is included using Mathematica software shooting quadrature.
2-Hydroxy-3-(1-naphthyloxy)propyl methacrylate (NOPMA) monomer was synthesized from reaction of 2-[(2-naphthyloxy)methyl]oxirane with methacrylic acid in the presence of pyridine. The polymerization of NOPMA was carried out by free radical polymerization method in the presence of AIBN at 60 °C. The structure of monomer and polymer was characterized by 1H-NMR, 13C-NMR and FT-IR spectroscopy techniques. The glass transition temperature and average-molecular weights of poly(NOPMA) were measured using differential scanning calorimetry and gel permeation chromatography, respectively. The thermal degradation behavior of poly(NOPMA) has been investigated by FT-IR studies of the partially degraded polymer and thermogravimetry. The cold ring fractions (CRFs) were collected at two different temperatures, initially fraction-1 (CRF1) is from room temperature to 320 °C, and the other fraction-2 (CRF2) is from 320 to 500 °C. The volatile products of the degradation were trapped at ?195 °C (in liquid nitrogen). All the fractions were characterized by FT-IR, 1H and 13C-NMR spectroscopic techniques, and the cold ring fractions (CRFs) were also characterized by GC–MS. For the degradation of polymer, the major compound between products of CRFs is α-naphthol. The GC–MS, FT-IR and NMR data showed that depolymerization corresponding to monomer was not prominent below 320 °C in the thermal degradation of poly(NOPMA). The mode of thermal degradation containing formation of the major products was identified. The dielectric permittivity (ε′), the loss factor (ε″) and conductivity (σac) were measured using a dielectric analyzer in the frequency range of 50 Hz to 20 kHz. 相似文献
Beypazari lignite was extracted with acetonltrile and acetonitrile/HClO4 and electrochemical hydrogenation of the lignite in acetonltrile/LlC104 in the presence of HClO4. was investigated. Controlled potential electrolysis experiments were carried out at -0.5 V vs a Ag/AgCl electrode. Infrared spectra of the products were measured and yields of extraction were determined. Extraction yields In acetonitrile and acetonitrile/HCIO4 were 9 and 17.3 %, respectively. The yield of extractable material did not increased in the electrochemical environment. Acetonltrile extraction produced residual matter with less hydroxyl groups. Stirring the lignite in acetonitrile(HClO4 for 7 hours oxidized both the extract and the residue. The residue seemed to contain less hydroxyl groups than that of the acetonltrile extraction residue and It has new carbonyl and etheric groups that were absent in the original lignite. It was found that the material extracted during electrochemical treatment by acetonitrile/HClO4 was hydrogenated and the coal matrix remained intact. As the quantity of HClO4 consumed in electrolysis was increased the amount of methyl groups in the extract also increased. Higher potentials are probably neccessary to hydrogenate the coal matrix by the electrochemlcally produced hydrogen atoms. 相似文献