密封环挠性安装形式对干气密封动态追随性的影响

基于气体润滑理论,并通过小扰动法建立了螺旋槽干气密封微扰膜压控制方程,在高速高压条件下获得了气膜动态特性系数;基于动力学相关知识,在考虑转轴轴向振动的情况下,利用气膜轴向动态刚度和阻尼系数分别求解了静环挠性安装、动环挠性安装和两环均挠性安装的干气密封挠性环运动方程.在不同轴向激励振幅、激励频率、挠性环质量、弹簧刚度和辅助密封圈阻尼下分别研究了三种典型结构干气密封动态追随性并进行了对比分析.结果表明:当轴向激励频率较高或挠性环质量较大时,静环挠性安装干气密封在刚受到外界激励时膜厚突变相对严重,动态追随性较差;在轴向激励频率较低且挠性环质量较小时,静环挠性安装干气密封相比动环挠性安装干气密封表现出更好的动态追随性;在三种密封环挠性安装形式中,两环均挠性安装干气密封动态追随性最好,且具有绝对优势.     

Gorenstein flatness and injectivity over Gorenstein rings

Let R be a Gorenstein ring.We prove that if I is an ideal of R such that R/I is a semi-simple ring,then the Gorenstein flat dimension of R/I as a right R-module and the Gorenstein injective dimension of R/I as a left R-module are identical.In addition,we prove that if R→S is a homomorphism of rings and SE is an injective cogenerator for the category of left S-modules,then the Gorenstein flat dimension of S as a right R-module and the Gorenstein injective dimension of E as a left R-module are identical.We also give some applications of these results.     

亚直不可约环成为全矩阵环的条件

给出了亚直不可约环是除环上的全矩阵环的一个新的条件。     

Schottky Mass Measurements of Cooled Exotic Nuclei

Projectile fragments of a ²⁰⁹Bi beam were separated in flight with the fragment separator FRS and injected into the experimental storage ring ESR. In the ESR a beam containing up to about 100 different isotopes was cooled to a relative velocity spread of δv/v=10⁻⁶ by means of the electron cooler. The image currents of the ions induced in a Schottky pick-up probe at each turn were recorded. A subsequent Fast Fourier Transformation of these signals yields the revolution frequencies of the different isotopes stored in the ESR. Unknown masses of more than 150 neutron-deficient nuclides in the element range of 52≤Z≤85 have been measured directly by Schottky Mass Spectrometry and in addition more than 60 new masses have been obtained from α-decay chains. These new mass data allow the location of the one-proton dripline and the prediction of the two-proton dripline for heavy nuclides. The experimental masses are compared with different theoretical predictions. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thiosemicarbazone complexes of the platinum metals. A story of variable coordination modes

Salicylaldehyde thiosemicarbazone (H₂saltsc) reacts with [M(PPh₃)₃X₂] (M = Ru, Os; X = Cl, Br) to afford complexes of type [M(PPh₃)₂(Hsaltsc)₂], in which the salicylaldehyde thiosemicarbazone ligand is coordinated to the metal as a bidentate N,S-donor forming a four-membered chelate ring. Reaction of benzaldehyde thiosemicarbazones (Hbztsc-R) with [M(PPh₃)₃X₂] also affords complexes of similar type, viz. [M(PPh₃)₂(bztsc-R)₂], in which the benzaldehyde thiosemicarbazones have also been found to coordinate the metal as a bidentate N,S-donor forming a four-membered chelate ring as before. Reaction of the Hbztsc-R ligands has also been carried out with [M(bpy)₂X₂] (M = Ru, Os; X = Cl, Br), which has afforded complexes of type [M(bpy)₂(bztsc-R)]⁺, which have been isolated as perchlorate salts. Coordination mode of bztsc-R has been found to be the same as before. Structure of the Hbztsc-OMe ligand has been determined and some molecular modelling studies have been carried out determine the reason for the observed mode of coordination. Reaction of acetone thiosemicarbazone (Hactsc) has then been carried out with [M(bpy)₂X₂] to afford the [M(bpy)₂(actsc)]ClO₄ complexes, in which the actsc ligand coordinates the metal as a bidentate N,S-donorformingafive-membered chelate ring. Reaction of H₂saltsc has been carried out with [Ru(bpy)₂Cl₂] to prepare the [Ru(bpy)₂(Hsaltsc)]ClO₄ complex, which has then been reacted with one equivalent of nickel perchlorate to afford an octanuclear complex of type [Ru(bpy)₂(saltsc-H)₄Ni₄](ClO₄)₄.     

On the shepherding of Uranian epsilon ring

To explain the long-term existence of Uranian narrow rings, we study the dynamical evolution of Uranian epsilon ring under the influence of its two shepherding satellites: Cordelia and Ophelia. The model of planar-elliptic restricted three-body problem is employed, in which the three bodies are Uranus, a satellite and a test particle. Dissipations due to interparticle collisions are also taken into consideration. A mapping system has been obtained based on the differential equation system. Numerical results show that only those particles originally lying in the libration region of the resonance can be shepherded. The size of the libration region depends mainly on the orbital eccentricity and mass of the shepherd satellite. For the outer shepherd Ophelia with larger orbital eccentricity, if its mass is a third of the nominal mass 2.5 × 10¹⁹ g, most of the orbits are regular and the outer edge of the ring can be shepherded, but more fuzzy than the inner edge. Thus we infer that Ophelia has a smaller mass.     

Thermal behavior of aromatic polyamic acids and polyimides containing oxadiazole rings

Two aromatic polyimides and the corresponding poly(amic acid)s, with oxadiazole and para/meta phenoxyphenylene rings in the backbone, were synthesized and the structure — thermal properties correlation was followed by dynamic mechanical analysis. Concerning the poly(amic acid)s, the glass transition domain was emphasized only for the compound with meta-oriented rings because the process of imidization takes place with increasing temperature. A multiplex experiment was performed to calculate the activation energy of the transition localized under 200°C. Consecutive heating-cooling-heating cycles were accomplished. All phenomena are discussed by cross-examination of the storage modulus (E′), loss modulus (E″) and loss factor tanδ variation with temperature.     

无外加氟施主产生KrF准分子发射谱实验研究

We report a new technique to suppress the low-spatial-frequency rings and ripples (LSFRs) of laser near-field intensity distribution in the spatial filter (SF) used in ICF laser drivers. This technique employs a spatial filter with Gaussian transmission, instead of the hard-edged pinhole, at the confocal plane of a Newtonian telescope. The resulting beam has a super-Gaussian transverse intensity profile without the LSFRs that certainly appear when a hard-pinhole was used as a filter in the conventional technique.     

交换环上上三角矩阵代数在全矩阵代数中的扩代数及其若当导子

设R是任意含么交换环,2是R的可逆元.M(n,R)表示R上所有n×n级矩阵形成的代数,T(n,R)表示R上所有n×n级上三角矩阵形成的代数.决定了T(n,R)在M(n,R)中的扩代数,并具体刻画了这些扩代数的若当导子.