Energy-Momentum Pseudo-Tensor of Relic Gravitational Wave of Both the Polarized States

Unlike usual celestial gravitational waves, the relic gravitational waves （RGWs） form random signals in curved spacetime background. We calculate the energy-momentum pseudo-tensor of a certain component of the RGWs propagating along arbitrary directions in Cartesian coordinates. It is found that the energy density of RGWs is positive definitely, and the momentum density components have reasonable behaviour. Such results may provide a theoretical basis for the detection of RGWs.     

Ni基乙烷脱氢催化剂的性能及其改进

过渡金属Ni是地球上储量丰富的金属元素, 在加氢脱硫、重整制氢等催化领域应用非常广泛, 但是关于Ni基催化剂在烷烃脱氢方面的研究较少; 因此, 本工作采用不同的方法, 制备了三种结构的Ni基负载催化剂, 即尖晶石分解型、浸渍型和钙钛矿析出型, 并在700 ℃、C₂H₆-N₂气氛中和50 mL•min^-1气体流速下, 探索了它们的乙烷脱氢性能. 结果表明: 尖晶石分解型催化剂Ni_1-xCu_xCr₂O₄还原后在Cr₂O₃表面形成Ni-Cu合金颗粒, 能有效钝化Ni的C—C键断裂活性, 提高乙烯的选择性. Ni含量过高时, Ni不能有效地分散而形成大的金属团簇, 造成乙烷过度裂解, 乙烯选择性较低. 浸渍负载型催化剂Ni_xM_y/Al₂O₃ (M为Cu或Ag) 比表面积大, 表面活性位点分散, 但活性金属与载体结合力弱, 在高温下不稳定; Cu或Ag与Ni形成合金, 可有效提高乙烯选择性, Ag较Cu的效果更佳. 钙钛矿析出型催化剂LaCr_1-xNi_xO₃(LCNi-100x)在还原气氛中析出均匀细小的Ni颗粒, 其与基体结合力强, 抗积碳性能和稳定性较高; 含15% Ni的LCNi-15还原后(R-LCNi-15)表现出最好的催化性能, 乙烯产率最高(24%), 同时具有较好的抗积碳性能和稳定性以及氧化再生性.     

基于曲线拟合的亚像素边缘定位方法的研究

图像的边缘定位是图像测量的关键之一,随着测量精度要求的提高,已由早期的像素级边缘定位发展到了现在的亚像素级边缘定位。根据地球在地球敏感器CCD阵面中的成像特性,提出了一种基于曲线拟合的亚像素边缘定位方法以获取地球“灼热圆盘”的边缘。该方法利用曲线拟合获得的拟合斜率以及灰度值来提取图像的边缘。仿真结果表明,采用曲线拟合亚像素边缘定位法可使图像的边缘定位精度达到百分之几个像素,具有较高的精度。     

两个含有平行交替链的新型二氰胺配位高聚物: {Mn(dmpz)[N(CN)2]2}2和{Cu(dmpz)[N(CN)2]2}2

Two new dicyanamide coordination polymers, {Mn(dmpz)[N(CN)2]2}2 (1) and {Cu(dmpz)[N(CN)2]2}2 (2)(dmpz=3,5-dimethylpyrazole), were synthesized and characterized by single crystal X-ray diffraction analysis and IR spectroscopy. In 1 and 2 the metal ions have two different coordination modes, where one is coordinated to four dicyanamide anions and two monodentate dmpz molecules to form a slightly distorted octahedral geometry, while the other adopts octahedral geometry, surrounded by four nitrile N atoms and two amide N atoms of the dicyanamide anions. Both complexes contain two alternating chains that are parallel to each other.     

POSITIVE DEFINITE PROBLEM OF ENERGY DENSITY AND RADIATIVE ENERGY FLUX FOR PULSE CYLINDRICAL GRAVITATIONAL WAVE

By using the general expressions of energy momentum pseudo-tensor of the cylin-drical gravitational waves (GW) given by Rosen and Virbhadra in Cartesian coor-dinates, the concrete forms of energy density and radiative energy flux of the pulse cylindrical GW are obtained. Their physical properties, suitable range and asymp-totic behaviour are considered. It is found that: For the region in which space radial coordinates to origin are greater than the pulse width of the pulse cylindrical GW, the energy density and radiative energy flux of the outward travelling pulse cylindrical GW propagating along at light-cone are positive definite. However, for the region in which the space radial coordinates are less than the pulse width, there is no guarantee for the positive definite property of the radiative energy flux of the outward travelling wave. Moreover, we show that the asymptotic behaviour of the energy and energy flux densities of the pulse cylindrical GW and that of the Riemann curvature tensor have good self-consistancy in space like, time like and null infinity regions.     

Bandt-Wang的一个定理的新证明

讨论格自仿Tile的边界结构,得到平面格自仿Tile的边界为简单闭曲线的一个充分条件;作为应用,给出Bandt-Wang的一个定理的新证明.     

Measurement of Magnetic Properties of an Inertial Sensor with a Torsion Balance

A torsion balance is constructed to accurately measure the magnetic properties of the real proof mass of the inertial sensor. The magnetic susceptibility and remnant moment of a titanium proof mass are measured in the first experiment, and further improvements and the potential sensitivity are also discussed. This is significant for choosing the material of the proof mass and investigating the magnetic disturbances acting on the proof mass.     

DETERMINATION OF THE PERIOD OF A TORSION PENDULUM BY THE FITTING METHOD IN REAL TIME

A phenomenological study on the fitting method in real time has been done, and the method was applied to process and analyze the extensive data of a long period torsion pendulum used to determine Newtonian gravitational constant G. The result shows that the fitting method in real time is effective to determine the period of a torsion pendulum with a relative precision of 10^-5 orders.     

Measurement of the Floor Tilt in Experimental Determination of the Gravitational Constant

A prototype of a device with an impact structure for measuring the floor tilt has been built in our laboratory. The mechanical construction and the capacitive transducer of the device are introduced. Experimental results indicate that the floor tilt is about 16#tad in our cavity laboratory, and the uncertainty AG/G caused by such tilt is less than 0.54 parts per million (ppm), so the floor tilt can be reasonably neglected in the experimental determination of the gravitational constant G with the total uncertainty of about l0ppm.     

一类广义Sierpinski海绵的填充测度

对于m≥2的任何整数m,本文定义了Rm中的一类广义Sierpinski海绵,同时给出了该类海绵的填充测度的计算公式.