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In this paper, the boundary stabilization of the Timoshenko equation of a nonuniform beam, with clamped boundary condition at one end and with bending moment and shear force controls at the other end, is considered.


It is proved that the system is exponentially stabilizable when the bending moment and shear force controls are simultaneously applied.


A fourthorder variational inequality of the second kind arising in a plate frictional bending problem is considered.


We then present the arithmetic for dynamic automatic identification of standing tree limbs, extracting basic growth characteristics of the standing trees such as the form, size, degree of bending and their relative spatial position.


Under the high bending vibration mode, resonance frequency and other parameters of longitudinal and radial wood were tested.

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 The recent opportunity of examining the faecal material of the waterscorpion Leccotrephes japonensis revealed a flagellate which had not previously been described from this host. After fuller investigation I found that it is a species new to science and should be referred to the genus Retortamona; I have named it Retortamonas leccotrephae sp. nov.The specimens of Leccotrephes japonensis used for studies on the parasitic flagellate R. leccotrephae, were collected from ponds on the outskirts of Shanghai, China.... The recent opportunity of examining the faecal material of the waterscorpion Leccotrephes japonensis revealed a flagellate which had not previously been described from this host. After fuller investigation I found that it is a species new to science and should be referred to the genus Retortamona; I have named it Retortamonas leccotrephae sp. nov.The specimens of Leccotrephes japonensis used for studies on the parasitic flagellate R. leccotrephae, were collected from ponds on the outskirts of Shanghai, China. Apart from studying the living flagellates, at the same time stained specimens were prepared for the detailed study of various structures. These specimens were fixed either in Hollande's or in Schaudinn's fluid; stained in Heidenhain's haematoxylin, and destained in 2％ aqueous phosphotungstic acid. Moskowitz' (1950) modification of the Protargol impregnation method was also used for staining.In the living state, the flagellare has a slender, slippershaped trunk with an anterior dorsal flexure. The mean body size, exclusive of the posterior spike, is 12.8μ×4.8μ. The length of the slender posterior spike varies from 4.6μ to 15.8μ. There are two flagella of unequal length. The longer one extends forwards and lashes rapidly, causing the animal to rotate and to pursue a special course. The shorter flagellum is directed backwards and usually lies in the cytostome; it moves in an undulating manner.In fixed and stained preparations, the flagellates, not including the posterior spike, show a sizerange of 6.2×2.2μto 15.6×5.4μ, with a mean of 11.9×3.4μ. The spike varied from 4.6μ to 13.6μ long, with an average length of 11.2μ. In general, a normal specimen of R. leccotrephae has a slender body; the anterior portion is narrower than the postcerior, and is markedly bent as shown in the living indivi.duals. The posterior portion of the body usually has a dorsal convexity, and the widest region is located near the twothirds of the bodylength from the anterior end.Near that edge of the nuclear membrane lying next to the cytostome, there are two minute, but separate, basal granules which give rise to the two flagella. The anterior flagellum is about as long as the body proper: much longer and more slender than the posterior flagellum, which usually lies within the cytostome, and commonly shows a series of two or three undulations; it often stains more deeply than the anterior flagellum.In hematoxylin preparations the nucleus is well stained, and clearly shows a layer of chromatin granules lying against the nuclear membrane, and a large central endosome, composed of a mass of granules.The cytostome is a large structure in this animal. It usually occupies about twothirds of the total length of the body proper. Along the margin of the cytostome there are two deeply staining fibres, the one on the right margin is longer than that on the left.Both the precystic forms and cysts of R. leccotrephae have been observed. The body of precystic individuals which are preparing to encyst, becomes smailer and rounds up; meanwhile, the chromatin of the nucleus condenses and forms a deeply staining endosome. The anterior flagellum is still disposed freely, and no cyst wall has as yet been formed. The borderline of the cytostome is distinct, but the two basal granules are visible only in favourable preparations. The mature cysts are nearly peanutshaped, and are about twice as long as wide. In the stained specimens they are about 4.6μ long and 2.4μ wide. The cyst wail is of uniform thickness, and the nucleus is visible at one end. The other conspicuous structures within the cyst are the two flagella and the cytostomial fibres, which are arranged as they are in the trophozoite, except that the anterior flagellum is here directed posteriorly.DISCUSSION & SUMMARYIn its general bodyform, R. leccotrephae closely resembles Mackinnon's R. agilis ('11) from cranefly larvae, and also Corradett's R. gryllotalpae ('37) from the mole cricket, but it is especially like Geiman's R. caudacus ('32) from the aquatic larvae ef certain beetles.  红娘华蛐的身体结构,一般与Mackinnon所述的R.(Embadomonas) agilis和Corradetti所述的R.grillotalpae相似,特别近似Geiman所述的R.caudacus(图15,16)。但红娘华蛐有大约等於体长2/3的大胞口,和长於或等於体长的针状尾巴,而且无论在生活时或固定染色後,头部均向背後扭曲(此较图1和15)。这些特性,显然与过去文獻中所记载的种类不同,故(氵夬)定为蛐属——新种。  The gabled leanto mill bent is an irregular rigid frame. The classical methods, e. g., the method of least work, slopedeflection, etc., for the analysis of the rigid frame are too tedious to be accepted, because they are not only dependent on the solution of simultaneous equations, but also the difficulty in establishing the equations. The method of moment distribution for computing the stresses of the same structure is also tedious because there are a great number of joint rotations and displacements... The gabled leanto mill bent is an irregular rigid frame. The classical methods, e. g., the method of least work, slopedeflection, etc., for the analysis of the rigid frame are too tedious to be accepted, because they are not only dependent on the solution of simultaneous equations, but also the difficulty in establishing the equations. The method of moment distribution for computing the stresses of the same structure is also tedious because there are a great number of joint rotations and displacements involving in the gabled leanto mill bents.A new method, symmetryantisymmetry method, for computing the stresses in symmetrical gabled leanto mill bents is presented in this paper. The foundamental conception of this method is to determine the shape constants and load constants of the unsymmetrical Γshaped frame as a whole and to treat it as a single member in the analysis.  關於披屋廠房排架的應力分析,目前已有不少切實可行的方法。但以這類排架內部組織的特殊,一般通用的基本方法,多不能為實際工作者赢得時間和精力的充分節約。本文目的,在提供一個分析對稱式斜頂披屋廠房拂架的簡便方法,予以適當修正,並可推廣應用於其他各種類型的披屋廠房排架。本法的主要特點是將排架中具有“Γ”形的曲桿當作一個基本構件,從而求出這個基本構件在兩端結點角變和位移以及荷載作用下的“形常数”與“載常數”;並將不對稱荷載件成“對稱的”與“不對稱的”兩種情形,使在分析計算過程中必須考慮平衡的結點數目诚至最少程度。  Many methods of analyzing statically indeterminate structures are now available. The method of redundant forces and that of deformations (i. e. the slopedeflection method), heretofore generally used in the U. S. S. R., both require the solution of a system of simultaneous simple equations. In the case of multistorey and multibay bents, the large number of such equations would greatly complicate the calculation work, it being both timeconsuming and liable to make mistakes. The method of moment distribution... Many methods of analyzing statically indeterminate structures are now available. The method of redundant forces and that of deformations (i. e. the slopedeflection method), heretofore generally used in the U. S. S. R., both require the solution of a system of simultaneous simple equations. In the case of multistorey and multibay bents, the large number of such equations would greatly complicate the calculation work, it being both timeconsuming and liable to make mistakes. The method of moment distribution simplifies calculations to a great extent, as there is no need to solve simultaneous equations, and therefore it has been warmly received bY practical engineers. Many soviet scholars are also devoted to its study. There are, however, defects in this method, namely: (1) Should the moments obtained in the successive cycles of distribution and carryingover prove to converge very slowly, twenty or more such cycles must be done if fairly accurate results are expected.(2) In the case of analyzing structures under various conditions of loading, while it is possible to find the influence moments by applying a unit moment at each joint as proposed by Prof. Hardy Cross, it would bequite laborious in the case of multistorey and multibay bents containing a large number of members, especially when subjected to unsymmetrical loadings.For the remedy of the first defect, such Chinese scholars as Profs. Lin Tung Yen, Chao Tsu Wu, Meng Chao Li and Tsai Fang Yin have made much contribution, and the author of this paper has recently written a discussion on the two papers of the lastmentioned scholar. For the remedy of the second defect, the author is unaware of any except that mentioned below.One of the soviet scholars, Dr. P. P. Shaggin (i.e.) has suggested important improvements with regard to both these defects. For the former, he adopted a method of singlecycle distribution; and for the latter, he invented the method of successive conjugation which greatly reduces the work of calculation in finding the influence moments. The essence of these methods is wellworth studying on the part of our Chinese engineers. After an intensive study, the author of this paper thinks that, while Dr. Shaggin's methods are quite correct in principle, his methods of calculation can still be somewhat improved, as described herein, so as to be made more easily applied in practice.This paper Shaggin based upon the book, (Calculation of Multistorey Frames by the Method of Successive Conjugation) published in 1954 by Dr. P. P. Shaggin in Leningrad, U. S. S. R., shows that, in applying a unit moment at each joint of a given statically indeterminate structure, one can easily find the influence moments at the ends of all the members, and that, after multiplying the unbalanced fixedend moments at each joint calculated in accordance with the given external loads, by the respective influence moments, the sum of such products added to the original fixedend moments will give at once the actual moments at each end of the members in the structure.Three notable improvements are indicated in this paper:(1) Dr. Shaggin's formula (5") on page 11 of his book, has been altered to formulas (3) in this paper. (2) For multistorey bents, Dr. Shaggin's method of finding the conjugate moments (i. e. the influence moments) by formulas is replaced by the usual method of simple momentdistribution.(3) The author of the paper has extended the method to the analysis of multistorey and multibay bents under any system of unsymmetrical loading.Of course, for structures under a single system of loading, influence moments need not be found and, generally speaking, it would be more convenient to apply the original method of momentdistribution; for a multistorey bent, it would be better, even in this case, to modify it by applying the method of successive conjugation.The author is of the opinion that the application of the methods described in this paper, being convenient and timesaving, would be useful to the practical engineers.  本文以蘇聯學者沙金博士最近出版之“用逐次互聯法計算多層排架”一書为依據,叙述在已知超靜定結構中每一結點,施以單位力矩,可以很容易地求得各桿端的影響力矩;然後依照其所受外力荷載,求得各結点處的定端力矩,分別乘以相當的影響力矩,相加之後並加以原有的定端力矩,即得各該桿端的實際力矩。若結構承受多種多样的荷載(不問其為豎向的或平向的、對稱的或不對稱的),用此篇所述之方法以推算各桿端力矩,著者認為最便利、最省時,並且適合實際工作者之需要。   << 更多相关文摘 
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