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1.
文章考察了Mo-SiO2催化剂体系在丙烯歧化反应过程中的动态ESR波谱,发现在催化歧化反应过程中有两种Mo5+顺磁中心,一种为扰动八面体配位,g||=1.89,g=1.94;另一种为扰动四棱锥配位,g||=1.86,g=1.95。测得同位素95,97Mo5+的各向异性超精细耦合常数A||=90.3×10-4cm-1,A=44.8×10-4cm-1;观测到反应产生的积炭信号,g≈2.0O2;氧阴离子自由基信号g1=2.018,g2=2.011,g3=2.005。用LCAO-MO理论对上述Mo5+的ESR波谱进行计算,求得分子轨道系数,发现并总结出△g||/△g与△g成直线关系,并建议用△g||/△g=4(△E(B2→E))/(△E(B2→B1)(β1/ε)2之比值作为衡量C4v扰动程度的尺度。  相似文献   

2.
The SU(2) Kepler problem is defined and analyzed, which is a Hamiltonian system reduced from the conformal Kepler problem on T*( 8 − {0}) by the use of the symplectic SU(2) action lifted from the SU(2) left action on the SU(2) bundle 8 − {0} → 5 − {0}. This reduced system has a parameter μ ε su(2) coming from the value of the moment map associated with the symplectic SU(2) action. If μ ≠ 0, the phase space of this system have a bundle structure with base space T*( 5 − {0}) and fibre S2. The fibre, a (co)adjoint orbit through μ for SU(2), represents the internal degrees of freedom, called the isospin, of the particle of this system. The SU(2) Kepler problem with μ ≠ 0 is then interpreted as describing the motion of a classical particle with isospin in the Newtonian potential plus a specific repulsive potential together with a Yang-Mills field. This Yang-Mills field is to be referred to as BPST Yang's monopole field in 5 − {0};, since it becomes the Belavin-Polyakov-Schwartz-Tyupkin instanton, restricted on S4. If μ = 0, the SU(2) Kepler problem reduces to the ordinary Kepler problem. Like the ordinary Kepler problem, the Hamiltonian flows of the SU(2) Kepler problem of negative energy are all closed. It is shown in an explicit manner that the energy manifolds and isoenergetic orbit spaces for the SU(2) Kepler problem of negative energy are both homogeneous manifolds on which SU(4) acts transitively to the right; those homogeneous manifold are classified into two, according as the parameter μ is zero or not. For a certain value of μ, however, they contracts to the manifold which represents the set of all the equilibrium states. The isoenergetic orbit spaces are finally shown to be symplectomorphic to certain Kirillov-Konstant-Souriau coadjoint orbits for U(4), if μ is not the exceptional value mentioned above.  相似文献   

3.
赵庆凯  陈小刚  崔继峰 《物理学报》2013,62(10):107201-107201
利用同伦分析方法, 研究了一类由柱形杂质随机嵌入基质所形成的、电场和电流密度满足J = σ E + χ |E|2E + η|E|4E 形式本构关系的高阶弱非线性复合介质在外加直流电场作用下的电势分布问题. 首先利用模函数展开法, 将本构方程及边界条件化成了一系列非线性常微分方程的边值问题; 再利用同伦分析方法进行求解, 给出了电势在基质和杂质区域的渐近解析解. 关键词: 高阶弱非线性复合介质 模函数展开法 同伦分析方法 电势分布  相似文献   

4.
The introduction of third generation robots in automated systems is impeded by the absence of 3-D sensors collecting panoramic range data at medium distance (0–10 meters) in a large volume (up to 100 m3). The work described in the present paper offers a certain number of solutions to this general problem. Our system is built around a 2-D passive machine vision connected to various cameras (VIDICON and CCD). The host computer (HP 1000) pilots numerous sorts of range finders (acoustic and optical).

The concept of multisensory range finders is introduced to allow the best use of each type (active methods). This 3-D vision has been tested in two fields of application:

• -in robotics for the absolute of a mobile robot;

• -in audiovisual for fixing objects or actors in a 3-D synthetic scene.

In some cases the absolute location problem is solved with an opto-electronic remote tracking measurement system. It is the last part of our 3-D machine vision.  相似文献   


5.
Five dimensional classical unified field theories as well as Yang-Mills theory with gauge group U(1), are described in terms of a Lorentzian five dimensional space V5 with metric tensor γβ which admits a space-like Killing vector ζ. It is assumed that: (1) V5 has the topology of V4 x S1, S1 is a circle and V4 is a four dimensional Lorentzian space that is asymptotically flat and (2) the Einstein tensor Γβ of V5 satisfies Γβ Uυβ 0 where U and υ are future oriented time-like vectors with γβυζβ = 0. The spinor approach of Witten [4], Nester [3] and Moreschi and Sparling [5] is used to show that the conserved five dimensional energymomentum vector P = ifΓβ = 0 then V5 must admit a time-like Killing vector. Lichnerowicz's results [1] then imply that V5 must be flat. A lower bound for P4 (the mass) similar to that found by Gibbons and Hull [6] is obtained.  相似文献   

6.
In this paper, a new method is designed which is accurate (λ/4, λ=632·8 nm) for finishing the small (less than 2·6 mm diameter and a center thickness of 0·4 mm) and soft germanium plano-convex lens. Special features of this process are as follows: (i) it produces a scratch-free and smooth surface; (ii) a precision blocking jig has been constructed which enables the operators to engage centering work of the plano-convex lenses (i.e. the lenses edge are co-axial with the optical axis); (iii) a modified moiré technique rapidly performs the centering test; and (iv) the simulation model has been developed for evaluating the polishing parameters used in this process.  相似文献   

7.
The performance of two-dimensional pressure sensor arrays, consisting of 13 × 13 deformable steel diaphragms, is investigated. The pressureinduced out-of-plane component of the displacement field of all 169 sensors is measured in parallel using phase-stepping speckle interferometry. Subsequent least-squares fitting of the theoretical field provides a quantitative measure of the average pressure acting on each sensor. With monotonically-increasing load and suitable calibration, each pressure value can be measured to an accuracy of better than 1% of the full scale deflection. The current pressure range of 0–2.74 kPa can be extended by increasing the number of interferograms recorded.  相似文献   

8.
The decay schemes of 1.2 min and 5.3 h 113Ag have been studied using Ge(Li) and NaI(Tl) detectors and a 4096-channel multiparameter pulse-height analyser system. The decay of 5.3 h 113Ag was found to involve 15 γ-rays and to produce 10 excited states in 113Cd at energies of 264.7, 298.0, 315.6, 583.9, 604.6, 681.1, 883.6, 936.9, 989.0 and 1195.2 keV. The italicized energies refer to negative parity states, through which 1.3% of the decays go to yield the isomer at 264.7 keV. The 604.6 keV level is thought to be a case|9/2 level similar for those found in several odd-mass Te and Xe isotopes. The 1.2 min 113mAg decay was found to populate several of the same levels in Cd and two additional levels at 452 and 689 keV. The 1.2 min 113Ag is the upper isomer with high spin, probably .  相似文献   

9.
A series of apatite-type La–Ge–O ceramics were prepared and their cation-defect at the 4f+6h sites and oxide ion-defect at 2a site were investigated. In LaxGe6O12+1.5x ceramics of x=6–12, the higher conductivities were obtained in the region of apatite composition, Lax(GeO4)6O1.5x−12 (x=8–9.33), and the highest conductivity was achieved for La9(GeO4)6O1.5 (x=9), where the number of cation (La3+) occupying the 4f+6h sites is 9 and the number of oxide ion occupying the 2a site is 1.5. The ceramics with cation- and oxide ion-defects were La9−0.66xSrx(GeO4)6O1.5 (x=0–1), La9−1.33xZrx(GeO4)6O1.5 (x=0–1), La9−xSrx(GeO4)6O1.5−0.5x (x=0–3), La9−xZrx(GeO4)6O1.5+0.5x (x=0–1), Lax(GeO4)3x−21(AsO4)27−3xO1.5 (x=0–3), Lax(GeO4)33−3x(AlO4)3x−27O1.5 (x=0–3), La9(GeO4)6−x (AlO4)xO1.5−0.5x (x=0–3), La9(GeO4)6−x(AsO4)xO1.5+0.5x (x=0–1), La9.33−xSrx(GeO4)6O2−0.5x (x=0–1.2) and Lax(GeO4)4.5(AlO4)1.5O1.5x−12.75 (x=8.8–9.83), which were prepared by the partial substitution of La3+and GeO44−of the basic apatite La9(GeO4)6O1.5 with Sr2+ or Zr4+ and AlO45− or AsO43−. Such substitutions lowered the conductivity of La9(GeO4)6O1.5. These results were discussed by the electrostatic interaction between Sr2+, Zr4+, AlO45− or AsO43− and oxide ion as a conductive species.  相似文献   

10.
吕志忠  张天祺  钟功祥 《物理学报》2015,64(17):174204-174204
利用钛宝石飞秒激光器输出的基频脉冲ω及其倍频脉冲2ω所构成双色场作用空气, 实验中检测到了中心波长处于真空紫外波段的四阶谐波. 在气体未发生电离的情况下, 四次谐波强度对双色场的能力依赖关系显示其产生是参量过程2ω+ω+ω→4ω的贡献. 当气体发生电离, 四次谐波强度与双色场相对相位有关, 可通过双色场相干控制. 实验研究了四次谐波对双色场相位的依赖性以及与太赫兹波的关联性, 其结果与数值模拟结果相符, 分析发现当气体发生电离时四次谐波的产生过程存在太赫兹辐射ΩTHz的参与, 是参量过程2ω+2ω±ΩTHz→4ω和2ω+ω+ω→4ω的共同贡献.  相似文献   

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