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991.
992.
The aim of the present study was to investigate whether turbulence intensity affects local skin temperature drop, and whether subjects’ dissatisfaction with draft can be correlated to the local skin temperature drop. Eighteen subjects were exposed to two levels of turbulence intensity (15% and 30%) at mean air velocities of 0.3 and 0.6 m/s respectively for 1 h. Subjective responses to draft were registered every 10 min and skin temperatures at the back of the neck were recorded throughout the sessions. More subjects felt uncomfortable due to draft when exposed to high turbulence than exposed to low turbulence. Skin temperature drop after 1 h exposure under high turbulence intensity is significantly larger than that under low turbulence intensity. Percentage of subjects dissatisfied with draft positively correlated to the local skin temperature drop. 相似文献
993.
桩-土作用机理与数值模拟 总被引:1,自引:0,他引:1
桩-土间相互作用机理的研究是保证桩基础在建筑荷载作用下安全稳定的关键。在分析桩-土间相互作用的基础上,利用有限元分析软件ANSYS中的Structural模块先进的非线性功能,进行桩的有限元分析,对桩-土间相互作用方式进行了数值模拟研究。建立了完整的桩模型,并建立弹簧单元以及表面效应单元以模拟土层对桩的作用力,得到了在建筑荷载和土层作用力下桩的位移量及其轴向应力分布,为建筑基础设计提供理论依据。 相似文献
994.
The pneumatic down-the-hole(DTH)hammer is one of the efficient equipments used in medium hard to very hard rock drilling frield,and any change in its structure design affects all performance parameters of a pneuamtic DTH hammer directly.Yet,owing to the complexity of the dynamic interaction among the components in DTH hammer systems,until now it has been difficult to obtain reliable estimates of the design parameter affects.Thus providing an design parameter optimization and the layout of dynamics behavior of DTH hammer is of great importance.This paper documents the development and solution of a computational model for the dynamic response of a pneumatic DTH hammer.The model consists of rigid piston dynamics equation and chamber thermodynamics equations.The resulting model represented by a set of coupled nonlinear differential equations were computed in Visual C++ program.The developed solutions are used to perform a parametric study to illustrate the inffluence of the piston mass and supply pressure on the impact performance of DTH hammer system. 相似文献
995.
996.
997.
住房和城乡建设部近期颁布了第四批建筑业10项新技术,为新技术的应用提供了十分有利的依据。针对新技术创新内容中的主要新技术,如钢结构、混凝土、钢筋及预应力、模板与脚手架、外墙保温及防水技术等,分析其应用现状,预测未来发展方向,并提出了一些建议。 相似文献
998.
GJ Bishop T Nomura T Yokota K Harrison T Noguchi S Fujioka S Takatsuto JD Jones Y Kamiya 《Canadian Metallurgical Quarterly》1999,96(4):1761-1766
Brassinosteroids (BRs) are steroidal plant hormones essential for normal plant growth and development. Mutants in the biosynthesis or perception of BRs are usually dwarf. The tomato Dwarf gene (D), which was predicted to encode a cytochrome P450 enzyme (P450) with homology to other P450s involved in BR biosynthesis, was cloned previously. Here, we show that DWARF catalyses the C-6 oxidation of 6-deoxocastasterone (6-deoxoCS) to castasterone (CS), the immediate precursor of brassinolide. To do this, we first confirmed that the D cDNA complemented the mutant light- and dark-grown phenotypes of the extreme dwarf (dx) allele of tomato. To identify a substrate for the DWARF enzyme, exogenous application of BR intermediates to dx plants was carried out. C-6 oxoBR intermediates enhanced hypocotyl elongation whereas the C-6 deoxoBR, 6-deoxoCS, had little effect. Quantitative analysis of endogenous BR levels in tomato showed mainly the presence of 6-deoxoBRs. Furthermore, dx plants were found to lack CS and had a high level of 6-deoxoCS in comparison to D plants that had CS and a lower level of 6-deoxoCS. Confirmation that DWARF catalyzed the C-6 oxidation of 6-deoxoCS to CS was obtained by functional expression of DWARF in yeast. In these experiments, the intermediate 6alpha-hydroxycastasterone was identified, indicating that DWARF catalyzes two steps in BR biosynthesis. These data show that DWARF is involved in the C-6 oxidation in BR biosynthesis. 相似文献
999.
JM Forbes B Leaker TD Hewitson GJ Becker CL Jones 《Canadian Metallurgical Quarterly》1999,55(1):198-208
BACKGROUND: Endothelin (ET) may be a mediator of injury following ischemia-induced acute renal failure (ARF). ET receptor (ETR) antagonists have been reported to increase survival rates and lower serum creatinines when administered postrenal ischemia-reperfusion injury in the rat. Renal cellular and extracellular matrix responses to this therapy have not been addressed. METHODS: We investigated the use of ETR antagonists, PD 156707 (ETA) and SB 209670 (ETA and ETB) in the treatment of sublethal postischemic ARF. The right kidney of female Sprague-Dawley rats weighing approximately 200 g was removed. After five days, the left renal pedicle was occluded for 45 minutes. Twenty-four hours after renal ischemia, one of two ETR antagonists, PD 156707 (N = 7) or SB 209670 (N = 8), was administered. Experimental animals were compared with an ischemic group receiving only saline (N = 9). Three nephrectomized groups that did not undergo ischemia but that received infusions of saline (N = 6), PD 156707 (N = 6), and SB 209670 (N = 6), respectively, were also studied. Animals were sacrificed one week postischemia. Quantitation of monocytes and macrophages (Mo/Mphi), alpha-smooth muscle actin-positive myofibroblasts, and collagens type III and IV was performed by immunohistochemical staining. Cell kinetics were examined by staining for apoptosis with terminal deoxyuridine triphosphate (dUTP) nick end labeling and for proliferation with proliferating cell nuclear antigen. RESULTS: All ischemic groups of rats initially developed raised serum creatinine levels; however, no significant difference was observed between the groups (Kruskal-Wallis). Creatinines returned to preischemic values in all groups by the time of sacrifice. No significant difference in kidney weights or body weights was found between groups. Histologically, infiltration of Mo/Mphi was significantly reduced in groups treated with ETR antagonists (P < 0.001). The presence of myofibroblasts was also significantly reduced in the antagonist-treated groups (P < 0. 001). This was also paralleled by reduced quantities of collagen IV in the treated rat groups (P < 0.001). The interstitial area was also significantly greater in the saline group (P < 0.001). The amount of collagen III did not significantly differ between rat groups. Apoptosis was reduced (P < 0.001) by treatment with ETR antagonists, whereas proliferation was enhanced (P < 0.005). All non-ischemic groups showed no variation in any parameter studied at this time point. CONCLUSIONS: Treatment of ischemic ARF in the rat with ETR antagonists PD 156707 and SB 209670 attenuated cellular infiltration and matrix accumulation. An advantage of one antagonist over the other could not be determined in this study. The marked discrepancy between function and pathology (former unchanged, latter markedly improved) may be due to the time frame of this experiment, and longer outcome measures need to be assessed. 相似文献
1000.
在铝电解自焙阳极糊生产过程中,需大量物粘结剂一液体沥青,而沥青由固体转变为液体过程中会产生大量的沥青烟,此沥青烟严重超过国家污染物排放标准,对人体健康带来极大危害,给生产、防喧来极大隐患。通过采用L-DCB1.1型电除尘器净化该烟气后,烟气排放达到国家污染物排放标准。 相似文献