激光双焦点测速中同一粒子的判别——一种研究气流湍流新方法的探讨

本文介绍了对激光双焦点技术的研究结果。从理论上分析了在该技术中,粒子依次穿越焦点的概率,提出了实际测量这种概率的逻辑判别方法。这样,解决了激光双焦点测速中同一粒子的判别问题而且对从拉格朗日观点研究湍流扩散提供了一种新的手段。文中给出了拉格朗日相关系数与同一粒子穿越概率的关系式和该技术对空气自由射流速度测量的结果。

自由湍流的后期运动

具有剪应力的自由湍流到下游相当远的地点由于能量的逐渐耗损将衰变成为类似均匀各向同性湍流的后期运动。如同处理后一种流动问题一样,我们现在根据湍流是由涡旋所组成的概念来求自由湍流的后期运动解。求涡旋运动解的动力学的基础是湍流速度涨落方程。在后期湍流场中湍流Reynolds数比较小,故方程中的非线性项可以略去。再考虑到组成湍流的涡旋尺寸比较小,在每个涡旋范围内平均湍流速度和它的坐标梯度可以近似地认为和坐标的改变无关。我们求线性化了之后的湍流速度涨落方程如下的近似解:涨落速度的一部分代表均匀各向同性湍流的后期运动:另一部分是和平均流速的坐标梯度成正比,后一部分要比前一部分为小。从这样的近似解得出的Reynolds剪应力是和平均流速的坐标梯度成正此。当作这一般解的特例我们求一个二元尾流的后期运动。在产生尾流的物体的后面还置放一个平面与尾流对称平面成垂直的栅格。这个栅格在它的下游可产生一个迭加在物体所产生的尾流场上的均匀各向同性的湍流(?)。我们的解是适用在离物体和栅格相当远处的后期运动,但此处的流场距栅格较近,所以栅格所产生的均匀各向同性湍流要比尾流的湍流度为高,因此一般解的近似条件是可以满足的。本论文给出尾流平均流速和速度涨落平方平均值的解。

Concentration distribution in crystallization from solution under microgravity

Concentration distribution in crystallization from solution under microgravity is numerically studied. A quasi-steady state growth and dissolution in a 2D rectangular enclosure filled with sodium chlorate (NaClO3) aqueous solution, in which one wall is the growth surface of the crystal and the opposite one is the dissolution surface, is considered. The solute transport process at the growth surface is described by the diffusion-reaction theory with finite interface kinetics coefficient. The results show that the concentration at the growth surface is supersaturated and the supersaturation distribution is of non-uniformity, i.e. the supersaturation in a region facing an incoming flow is high. On the other hand, the non-uniformity of supersaturation at the growth surface is closely related to the gravity level even under microgravity, it exponentially increases as the thermal Rayleigh number on behalf of the gravity level rises.

[Discurso do Deputado José Cruciano : Sessão da Câmara dos Deputados de 22 de abril de 1963]

Discorre sobre o significado da construção de Brasília e sua irreversibilidade. Apresenta dados sobre os custos desta, que desmentem as notícias sobre o fato. Enumera as medidas que necessitam serem tomadas para a consolidação da capital federal e solicita aos deputados a dar tramitação aos projetos pendentes para este fim.

油气混输系统的实验研究与实验模拟准则

中国科学院九五重大项目!（KZ951－A1－405）

Eredu latindarraren eragina euskal deklinabidearen XIX. mendeko deskribapenetan

R. Etxepare, R. Gómez & J. A. Lakarra (arg.), Beñat Oihartzabali Gorazarre - Festschrift for Bernard Oyharçabal. Donostia-San Sebastián: Gipuzkoako Foru Aldundia & UPV/EHU.

圆桩振荡绕流对淤泥床的冲蚀

本文实验研究不同圆柱直径和不同初始圆柱与床面距离时圆柱振荡绕流对其下方淤泥介质床面的冲蚀作用。实验得到了在产生冲蚀的临界条件下圆柱与床面初始无量纲距离随振荡流Ｋｃ数的变化规律。由于不同的无量纲间距下圆柱振荡绕流分离流动的旋涡运动类型的不同，形成了冲蚀床表面的不同类型的表面冲蚀图象。

微重力下环境压力和辐射再吸收对火焰沿薄燃料表面传播的影响

当环境气体不具备辐射特性时(例如环境气体为O2-N2),在较小的环境压力下,火焰向燃料表面的热传导是火焰传播的主要驱动力.但随着环境压力的增大,火焰传播速度越来越大,火焰对燃料表面的热辐射逐渐成为火焰传播的主要驱动力之一.当环境气体具有较强的辐射特性时(例如环境气体为O2-CO2),在较小的环境压力下,火焰前沿环境气体的辐射再吸收将强化火焰对燃料表面的传热、热辐射和热传导在火焰传播机理中均起重要作用.随着环境压力的增大,氧气向火焰的扩散加强,燃烧反应加剧,火焰传播加速.当环境压力大于一定值时,进一步增大环境压力,环境气体的辐射再吸收使火焰对燃料表面的热辐射减弱.因此,火焰传播速度反而随着环境压力的增大而减小,火焰向燃料表面的热传导逐渐成为火焰传播的主要驱动力.

Objektu-komunztadura XIX eta XX. mendeetako euskal gramatiketan

Beatriz Fernández eta Pablo Albizu (arg.)

Aristophanis comoediae undecim, graece et latine : ad fidem optimorum Codicum MSS. emendatae cum nova octo comoediarum interpretatione latina, e notis ad fingulas ineditis Stephani Bergleri, nec non Caroli Andreae Dukeri ad quatuor priores, accedunt deperditarum comoediarum fragmenta a Theod. Cantero et Gul. Coddaeo collecta, earumque indices a Joh. Meursio & Joh. Alb. Fabricio digefti, curante Petro Burmanno Secundo, qui praefationem praefixit

Aristófanes nasceu em Atenas entre 450 e 445 a.C. e morreu por volta de 388 a.C. Considerado o principal representante da comédia antiga, em suas peças predominavam a sátira política e a social. Suas primeiras comédias foram assinadas sob pseudônimo e somente após ‘Os Acarnianos’ (ou ‘Acarnanos’) tornou-se conhecido. Da sua obra apenas onze peças conservaram-se integralmente. Esta coleção, em dois volumes, contém onze peças. O primeiro volume inclui ‘Os Plutos’ (publicada no ano de 388 a.C.), sua ultima comédia; ‘As Nuvens’ (423 a.C.); ‘As Rãs’ (405 a.C.); ‘Os Cavaleiros’ (424 a.C.); ‘Os Acarnianos’ (425 a.C.) e ‘As Vespas’ (422 a.C.). O segundo volume contém ‘Os Pássaros’ (414 a.C.); ‘A Paz’(421a.C.); ‘A Assembleia das mulheres’ (392 a.C.); ‘As Convocadas’ (411 a.C.) e ‘Lisistrata’ (411 a.C.)

Dänemarks Fischereierträge 1996 konstant - aber deutlicher Anstieg 1997

Although landings in 1996 were 319 000 t down (–16 %) from 1995 the returns from fishery in 1996 were almost as high as 1995 ( 3014 mio. dkr; – 0.2 %). Industrial fishery alone decreased by 268 000 t. The average price for all landed species was 1.81 dkr/kg, an increase of 19 % compared to 1995, with a range of 0.61 dkr/kg for industrial fish (sandeel etc.) to 62 dkr/kg for sole. 1997 the fishery scene improved again. Already in November landings reached 1.74 mio. t, more than all 1996. Price increase was not as strong as 1996; on average 5 % until November. Total return until November was, however, alreday 3250 mio. dkr; 405 mio dkr above total return of 1996.

Ajuste psicológico y salud mental de la población inmigrante : influencia del género y la cultura

481 p.