共查询到20条相似文献，搜索用时 812 毫秒
1.
任柏帜 《重庆大学学报(英文版)》2004,3(2):30-33
IntroductionTherainstormintensityformulaisanimportantandfundamentalformulainmodernmunicipaldrainagedesign,asthebasisincalculatingrainstormgroundrunoffandengineeringtheflowvolumeofaproject.Itdirectlyinfluencestheinvestmentbudgetandthereliabilityofamunicipaldrainagesystemtobebuilt.AccordingtoSpecificationsofDrainageDesignOutdoor(GBJ14-87)[1],thedesignflowvolumeofarainwaterpipesystemshouldbecalculatedbythelocalrainstormintensityformula.Thereliabilityofadrainagesystemhasdirectrelationtotherains… 相似文献
2.
1ISSUEUNDERDlSCUSSIONThepass/falllevelofanexampaperisthedivisionlinewherebythescoresaboveandequalare"pass"andthosebeloware"fall".InaccordancewiththerelevantdocumentsconcerningCollege-levelExamsForselftaughtStudents(referredtoasCLESSforconvenience)[1],weho1dthattheseexamsarespecialcriterion-referencedexamswithrestrictedpass/fai1standardsp/flevelsinvarioussubjectsaredecidedbythefollowingtwocriteria.l.Theexamsrequirethestudentstomasteracertainpropor-tionofthecontentinthesyllabusforCLE… 相似文献
3.
对于任意x∈R,定义[x]为不大于x的最大整数,则有:(1)[x]∈Z;(2)[x]≤x(当且仅当x∈Z时取等号);(3)令x=[x] 9,则0≤y相似文献
4.
混杂系统是离散事件系统(DES)与连续变量系统(CVS)相混合而形成的统一的动力系统.对于随机混杂系统[1],不仅系统具有混杂的特性,同时又有随机的特性[2][4],其连续状态或离散状态相互合成而又服从概率分布,这给该系统稳定性的研究都增加了难度.定义1随机混杂系统(SHS)[1]:我们定义一个随机 相似文献
5.
6.
(本讲适合高中)1知识介绍1.1函数f(x)=[x]的概念与性质设x、y∈R.记f(x)=[x]表示不小于实数x的最小整数,[x]表示不超过实数x的最大整数.(1)[x]-1相似文献
7.
设E是一实Banach空间,K是E的一非空闭凸子集.设f:K→K是一压缩映象,T1,T2,…,Tn:K→K是具序列{kn}(c)[1,+∞),lim n→∞ kn=1的有限簇一致L-Lipschitzian渐近伪压缩映象,且∩N/(i=1)F(Ti)≠φ.设序列{xn}定义为xn+1=(1-αn-βn)xn+αnf(xn)+βnTrn/nxn,其中{αn},{βn} (c)[O,1],rn=n mod N是值域为{ 1,2,…,N}的模函数.在一定条件证明了迭代序列{xn}强收敛于T1,T2,…,Tn的公共不动点.推广和改进了张石生等人的最新结果. 相似文献
8.
何成刚 《历史教学(高校版)》2007,(13)
1923年,由全国教育联合会组织编制并颁布的<初级中学历史课程纲要>(常乃德起草,以下简称<纲要>)[1],引起了大家的研究兴趣,其研究成果推动了民国中学历史教育研究的深入.不过还有继续深入探讨的必要.下面笔者拟主要从<纲要>的核心内容"课程目标"与"课程内容"两个角度进行研讨. 相似文献
9.
<正>先分析学生对2006两道高考题的错解.例1(2006年天津高考题)已知函数y=f(x)的图象与函数y=ax(a>0且a≠1)的图象关于直线y=x对称,记g(x)=f(x)[f(x)+f(2)-1],若g(x)在区间12,2上是增函数,则实数a的取值范围是() 相似文献
10.
考虑时滞微分方程：dN(t)/dt=r(t)N(t)[1-N(g(t))/k],t≥0，其中α≥是两个正奇数之比，获得了保证其每一正解趋于正平衡 的一族充分条件。 相似文献
11.
RH和RH-KTB精炼过程中钢液流动和混合特性的研究 总被引：7，自引：0，他引：7
The flow and mixing characteristics of molten steel during the vacuum circulation refining,including RH(Ruhrstahl-Heraeus) and RH-KTB(Ruhrastahl-Heraeus-Kawasaki top blowing) processes,were investigated on a 1/5 linear scale water model of a 90t multifunction RH degasser,The circulation rate was directly and more accurately determined,using a new method by which the more reliable results can be obtained.The fluid flow pattern and flow field in the ladle were demonstrated,observed and analyzed.The mixing time of liquid in the ladle was measured using electrical conductivity method.The residence time distribution in the RH model was obtained by tracer response technique.The influence of the main technological and geometric factors,including the gas top blowing*(KTB) operation,was examined.The results indicated that the circulation rate of molten steel in the RH degasser can be fairly precisely calculated by the formula:Q1p=0.0333Qg^0.26Du^0.69Dd^0.80(t/min),where Qg-the lifting gas flow rate(NL/min);Du and Dd-the inner diameters of the up and down-snorkels(cm),respectively.The maximum value of circulation rate of molten steel in the case of the 30cm diameters either of the up-and down-snorkels for the RH degasser(the “Saturated” rate) is approximately 31 t/min.the corresponding gas flow rate is 900NL/min.Blowing gas into the vacuum chamber through the top lance like KTB operation does not markedly influence the circulatory flow and mixing charateristics of the RH process under the conditions of the present work.There exist a major loop and a large number of small vortices and eddies in the ladle during the RH refining process.A liquidliquid two-phase flow is formed between the descnding stream from the down-snorkel and the liquid around the stream.All of these flow situation and pattern will strongly influence and determine the mixing and mass transfer in the ladle during the refining.The correlation between the mixing time and the stirring energy density is τmε^0.50 for the RH degasser.The mixing time rapidly shortens with an increase in the lifting gas flowrate.At a same gas flow rate,the mixing times with the up-and down-snorkel diameters either of 6 and 7cm are essentially same.The 30cm diameters either of the up-and down-snorkels for the RH degasser would be reasonalble.The concentration-time curve showed that three circulation cycles are at least needed for complete mixing of the liquid steel in the RH degasser. 相似文献
12.
竹炭负载二氧化钛吸附甲醛的研究 总被引：1，自引：0，他引：1
采用溶胶-凝胶法制备TiO2溶胶,采用浸渍-过滤法将TiO2负载于载体颗粒竹炭(BC)的表面,制成竹炭负载二氧化钛的复合物TiO2/BC,并对甲醛进行吸附实验。结果表明:BC和TiO2/BC对甲醛都具有较强的吸附,但是达到饱和吸附时,TiO2/BC的吸附量较大,单位时间内TiO2/BC的吸附甲醛的质量比BC多,且经过多次负载的TiO2/BC其对甲醛的吸附量增加,以负载3次为佳。 相似文献
13.
钢液真空循环精炼过程的物理模拟 总被引：2，自引：0，他引：2
魏季和 《上海大学学报(英文版)》2003,7(1):1-17
1 Ｉｎｔｒｏｄｕｃｔｉｏｎ Ａｓａｓｅｃｏｎｄａｒｙｓｔｅｅｌｍａｋｉｎｇｔｅｃｈｎｏｌｏｇｙ ,ｔｈｅＲＨ(Ｒｕｈｒｓｔａｈｌ Ｈｅｒａｅｕｓ)ｖａｃｕｕｍｃｉｒｃｕｌａｔｉｏｎｒｅｆｉｎｉｎｇｐｒｏ ｃｅｓｓｈａｓｂｅｅｎａｐｐｌｉｅｄｗｉｄｅｌｙａｎｄｄｅｖｅｌｏｐｅｄｒａｐｉｄｌｙｉｎｐｒｅｖｉｏｕｓｆｏｕｒｄｅｃａｄｅｓ .Ｗｉｔｈａｃｏｎｔｉｎｕｏｕｓｌｙｇｒｏｗｉｎｇｄｅｍａｎｄｆｏｒｈｉｇｈｑｕａｌｉｔｙａｎｄｈｉｇｈｌｙｃｌｅａｎｓｔｅｅｌ,ｉｔｈａｓｎｏｗｂｅｃｏｍｅ ,ｔｏａｃｏｎｓ… 相似文献
14.
Lattice Boltzmann method was used to numerically investigate the motion and orientation distribution of cylindrical and cubic particles in pipe flow with high concentration and high particle to pipe size ratio. The transient impulse model of 3D collisions between particles and between particle and wall is proposed. The numerical results are qualitatively in agreement with and quantitatively comparable to the experiment data. The results show that the increases of both the cylindrical particle to pipe size ratio and the particle aspect ratio decrease the rotation about all axes. All rotations of cubic particles decrease with increasing the particle concentration. The cubic particles, rotating more drastically in the flow with large Reynolds number, rotate faster than the cylindrical particles with the same size. The cylindrical particles align with the flow direction more obviously with decreasing Reynolds numbers. However, the orientations of cubic particles are spread all over the range with no significant difference in magnitude, and the Reynolds numbers have no obvious effect on the orientations of cubic particles. 相似文献
15.
This investigation assessed effects of three increasingly inclusive versions of the Behavioral Consultation (BC) model on problem behavior of students in mainstream classrooms in an effort to develop an effective and efficient approach to prereferral intervention. Subjects were 43 general educators, their 43 most difficult-to-teach students (without disabilities), and 12 school consultants, representing seven inner-city middle schools. Teachers and students were assigned to three BC groups, representing least (BC 1), more (BC 2), and most (BC 3) inclusive variants of BC, and one control group. Preintervention, postintervention, and follow-up observations of student behavior indicated that more inclusive BC versions exerted stronger effects than the least inclusive variant in reducing problem behavior. Theoretical and practical implications for consultation-related activity are discussed. 相似文献
16.
《Contemporary educational psychology》1988,13(2):146-156
Using adaptation level (AL) theory as a frame of reference for determining the perceived value of college grades, 166 students rated the following sources of influences affecting grade incentive AL: self, peers, major field, and parents. Subjects also provided GPAs, ACT scores, and evaluative ratings for the grade categories of A-F. Results revealed that AL values for family were most similar to AL values for self and that family influences were more significant than any other in affecting overall AL value. Students having higher incentive ALs rated all grade categories less positively than did student having lower ALs. Grade AL was found to predict GPA significantly (even when ACT score was controlled); it did not predict satisfaction with grades, which was more directly a function of GPA. Results were taken to suggest that college grades, for both students and professors, are best conceptualized as an adaptation level phenomenon in which their meaning for the individual depends upon the personal and situational frames of reference within which they are given and received. 相似文献
17.
In this study,particle image velocimetry was applied to investigate flow fields of wormlike micelle(WLM) fluids in a mixing tank equipped with a four-blade,down-pumping,pitched blade turbine. First,the rheology of WLM fluids was investigated,and the Carreau model was utilized to describe their apparent viscosity. Then,the effects of the rotation speeds and rheological properties on the flow fields were studied using different WLM fluids at different rotation speeds. The results revealed that with increasing Reynolds number,the discharge angle decreases and the carven size increases. Furthermore,elastic effects of WLM fluids lead to a more curved flow and a smaller carven. 相似文献
18.
Heat transfer between gas-solid multiphase flow and tubes occurs in many industry processes, such as circulating fluidized
bed process, pneumatic conveying process, chemical process, drying process, etc. This paper focuses on the influence of the
presence of particles on the heat transfer between a tube and gas-solid suspension. The presence of particles causes positive
enhancement of heat transfer in the case of high solid loading ratio, but heat transfer reduction has been found for in the
case of very low solid loading ratio (M
s of less than 0.05 kg/kg). A useful correlation incorporating solid loading ratio, particle size and flow Reynolds number
was derived from experimental data. In addition, thek-∈ two-equation model and the Fluctuation-Spectrum-Random-Trajectory Model (FSRT Model) are used to simulate the flow field
and heat transfer of the gasphase and the solid-phase, respectively. Through coupling of the two phases the model can predict
the local and total heat transfer characteristics of tube in gas-solid cross flow. For the total heat transfer enhancement
due to particles loading the model predictions agreed well with experimental data.
Project supported by National Natural Science Foundation for Distinguished Young Scholars (No. 50025618) 相似文献
19.
Thebubblecolumnreactor (BCR) ,withbatchfeedandcontinuousgasaerated ,hasobtainedwideapplica tionsinbiochemicalengineering ,chemicalengineeringandwastewatertreatment ,etc .OneimportantfeatureofBCRisthattheconversionandtheyieldofthereactioncanbehighlyincreasedundertheunsteady stateopera tion .Sincethemassandtheheattransferpropertiesinaprocessmainlydependontheflowbehavior ,itisstronglydesirabletoinvestigatetheunsteady stateflowstructurebeforethedesignandscale upofBCRwithhighreactiveconversionsa… 相似文献
20.
魏季和 《上海大学学报(英文版)》2002,6(1):1-23
The available studies in the literature on physical and mathematical modeling of the argon-oxygen decarburization(AOD) process of stainless ssteel have briefly been reviewed.The latest advances made by the author with his research group have been summarized.Water modeling was used to investigate the fluid flow and mixing characteristics in the bath of an 18t AOD vessel,as well as the “back-attack” action of gas jfets and its effects on the erosion and wear of the refractory lining,with sufficiently full kinematic similarity.The non-rotating and rotating gas jets blown through two annular tuyeres,respectively of straight-tube and spiral-flat tube type.Were employed in the experiments.The geometric similarity ratio between the model and its prototype(including the straighttube type tuyeres)was 1:3 ,The influences of the gas flow rate,the angle included between the two tuyeres and other operating parameters,and the suitability of the spiral tuyere as a practical application,were examined.These latest studies have clearly and successfully brought to light the fluid flow and mixing characteristics in the bath and the overall features of the back-attack phenomena of gas jfets during the blowing.nd have offered a better understanding of the refining process.Besides,mathematical modeling for the refining process of stainless steel was carried out and a new mathematical model of the process was proposed and developed.The model performs the rate calculations of the refining and the mass and heat balances of the system.Also,the effects of the operating factors,including adding the salg materials.crop ends,and scrap,and alloy agents;the non-isothermal conditions;the changes in the amounts of metal and slag materials,crop ends,and scrap,and alloy agents;the non-isothermal conditions;the changes in the amounts of metal and slag during the refining;and other factors were all considered.The model was used to deal with and analyze the austenitic stainless steel making (including ultra-low carbon steel) and was tested on data of 32 heats obtained in producing 304 grade steel in an 18t AOD vessel.The changes in the bath compostion and temperature during the refining process with time can be accurately predicted using this model.The model can provide some very useful information and a reliable basis for optimizing the process practice of the refining of stainless steel and control of the process in real-time and online. 相似文献