Search

Quantum chemical calculation is an important method to investigate the molecular structures for multi-atom molecules. The determination of electronic configurations and the accurate description of the symmetry of molecular orbitals are critical for understanding molecular structures. For the molecules belonging to high symmetry group, in the quantum chemical calculation the sub-group is always adopted. Thus the symmetries of some electric states or some molecular orbitals, which belong to different types of representations of high symmetry group, may coincide in the sub-group presentations. Therefore, they cannot be distinguished directly from the sub-group results. In this paper, we provide a method to identify the symmetry of molecular orbitals from the theoretical sub-group results and use this method to determine the symmetry of the highest occupied molecular orbitals (HOMO) of the sulfur hexafluoride SF6 molecule as an example. Especially, as a good insulating material, an important greenhouse gas and a hyper-valent molecule with the high octahedral \begin{document}$ O_h $\end{document} symmetry, SF6 has received wide attention for both the fundamental scientific interest and practical industrial applications. Theoretical work shows that the electronic configuration of ground electronic state \begin{document}$ ^1{\rm A_{1g}} $\end{document} of SF6 is \begin{document}${({\rm {core}})^{22}}{(4{\rm a_{1\rm g}})^2}{(3{{\rm t}_{1\rm u}})^6}{(2{{\rm e}_{\rm g}})^4}{(5{{\rm a}_{1\rm g}})^2}{(4{{\rm t}_{1\rm u}})^6}{(1{{\rm t}_{2\rm g}})^6}{(3{{\rm e}_{\rm g}})^4}{(1{{\rm t}_{2\rm u}})^6}{(5{{\rm t}_{1\rm u}})^6}{(1{{\rm t}_{1\rm g}})^6} $\end{document} and the symmetry of the HOMOs is \begin{document}$ T_{1g} $\end{document}. However, in some literature, the symmetry of HOMOs of SF6 has been written as \begin{document}$ T_{2g} $\end{document} instead of \begin{document}$ T_{1g} $\end{document}. The reason for this mistake lies in the fact that in the ab initial quantum chemical calculation used is the Abelian group \begin{document}$ D_{2h} $\end{document}, which is the sub-group of \begin{document}$ O_h $\end{document}, to describe the symmetries of molecular orbitals of SF6. However, there does not exist the one-to-one matching relationship between the representations of \begin{document}$ D_{2h} $\end{document} group and those of \begin{document}$ O_h $\end{document} group. For example, both irreducible representations \begin{document}$ T_{1g} $\end{document} and \begin{document}$ T_{2g} $\end{document} of \begin{document}$ O_h $\end{document} group are reduced to the sum of \begin{document}$ B_{1g} $\end{document}, \begin{document}$ B_{2g} $\end{document} and \begin{document}$ B_{3g} $\end{document} of \begin{document}$ D_{2h} $\end{document}. So the symmetry of the orbitals needs to be investigated further to identify whether it is \begin{document}$ T_{1g} $\end{document} or \begin{document}$ T_{2g} $\end{document}. In this work, we calculate the orbital functions in the equilibrium structure of ground state of SF6 by using HF/6-311G* method, which is implemented by using the Molpro software. The expressions of the HOMO functions which are triplet degenerate in energy are obtained. Then by exerting the symmetric operations of \begin{document}$ O_h $\end{document} group on three HOMO functions, we obtain their matrix representations and thus their characters. Finally, the symmetry of the HOMOs is verified to be \begin{document}$ T_{1g} $\end{document}. By using this process, we may determine the molecular orbital symmetry of any other molecules with high symmetry group.

This paper deals with the scanner exterior calibration algorithm when the scanner is arranged by the robot and the object scanned is fixed on a rotate device in the Robot Remanufacturing System. The method of calibrating the relationship between the scanner coordinate and the robot Tool0, such as the rotation, R x , Ry, Rz, and the transformation X, Y, Z is studied. The data of Tool0 can be directly obtained from the relationship with the robot base-coordinate. So, the coordinate relationship between the scanner coordinate and the robot base coordinate can be easily gotten. This paper explains the basic algorithm theory, computing method, data collecting process and the resulted data in detail. The calibration algorithm is deduced under the orthogonal coordinate.

We investigate the above-threshold ionization of an atom in a combined infrared (IR) and extreme ultraviolet (XUV) two-color laser field and focus on the role of XUV field in the high-order above-threshold ionization (HATI) process. It is demonstrated that, in stark contrast to previous studies, the XUV laser may play a significant role in atomic HATI process, and in particular, the XUV laser can accelerate the ionized electron in a quantized way during the collision between the electron and its parent ion. This process cannot be explained by the classical three-step model. Our results indicate that the previously well-established concept that HATI is an elastic recollision process is broken down.

We study nonsequential double ionization (NSDI) processes of an atom by applying the frequency-domain theory based on the nonperturbative quantum electrodynamics. We obtain the transition formulas that describe the NSDI processes caused by the collision ionization (CI) and the collision-excitation ionization (CEI) mechanisms. By analyzing the NSDI results of each above-threshold ionization (ATI) channel, we investigate the contributions to the NSDI from the backward and forward collisions. In particular, for the CI process, the backward collision makes a major contribution to the NSDI probability, whereas for the CEI process, it depends on the characteristics of the laser-atom system: if the energy that the recolliding electron needs to excite a bound electron is much larger than the laser photon energy, such as for the case of helium in this work, the backward collision dominates the contribution; otherwise, the forward collision dominates the contribution. We also discuss the source of interference fringes in the NSDI momentum spectra due to the CI mechanism and find that the fringes can be predicted by using a simple cosine function. This work can be regarded as a development of the frequency-domain theory, which may shed light on the study of multiparticle dynamics in intense laser fields.

Using a triatomic molecular model, we show that the interference pattern in the high-order above-threshold ionization (HATI) spectrum depends dramatically on the charge distribution of the molecular ion. Therefore the charge distribution can be considered a crucial factor for imaging a molecular geometric structure. Based on this study, a general destructive interference formula for each above-threshold ionization channel is obtained for a polyatomic molecule concerning the positions and charge values of each nuclei. Comparisons are made for the HATI spectra of ${\mathrm{CO}}_{2}$, ${\mathrm{O}}_{2}$, ${\mathrm{NO}}_{2}$, and ${\mathrm{N}}_{2}$. These results may shed light on imaging complex molecular structure by the HATI spectrum.

A new idea is proposed that preprocessing is the key to improving the precision of short-term load forecasting (STLF). This paper presents a new model of STLF which is based on pattern-base. Our model can be described as follows: firstly, it recognizes the different patterns of daily load according such features as weather and date type by means of data mining technology of classification and regression tree (CART); secondly, it sets up pattern-bases which are composed of daily load data sequence with highly similar features; thirdly, it establishes ANN forecasting model based on the pattern-base which matches to the forecasting day. Since the patterns of daily load are treated precedingly, the rule of the historical data sequence is more obvious. Accordingly, we need not input pattern characters when establishing ANN load forecasting model. The model has many advantages: first, since the training data has similar pattern to the forecasting day, the odel reflects the rule of daily load accurately and improves forecasting precision accordingly; second, as the pattern variables need not to be input into model, the mapping of the categorical variables is solved; third, as inputs are reduced, the model is simplified and the runtime is lessened. The simulation indicates that the new method is feasible and the forecasting precision is greatly improved.

In this paper, a knowledge-based intelligent system for power customer service management is proposed. As the value of knowledge management and customer relationship management has been well recognized, it is essential to make optimal reuse of knowledge of customer among various functional units of the enterprise. As the power company is the industry that provides standard service, it is important to ensure that the customer service staff can access and be trained up with dynamically updated knowledge that adjusts to the changing environment of the enterprise in customer services. However, conventional way of customer service management is inadequate to achieve knowledge acquisition and diffusion, service automation and satisfaction measurement, and thus unfavorable for the continuous improvement of the customer service quality. This paper discusses the frame and process of the knowledge-based intelligent service system for power customer, and puts forward some aspects that should be noted during the period of implementation. It is verified that the proposed model provides high quality customer services with fast and efficient responses to customer demands.

A displacement search algorithm (DSA) is proposed in this paper to perform deformable block matching. A sub-pixel accuracy prediction and two-mode hybrid method is further proposed. The results show that DSA has about 2 dB better than full search. DSA gets better subjective and objective quality with reduced computation than gradient-based search algorithm, and much easier to implement with VLSI.

With the development of electronic industry, accurate load forecasting of the future electricity demand plays an important role in regional or national power system strategy management. Electricity load forecasting is difficult due to the nonlinearity of its influencing factors. Support vector machine (SVM) have been successfully applied to solve nonlinear regression and time series problems. However, the application to load forecasting is rare. In this study, a model of support vector machine is proposed to forecast electricity load. The model overcomes the disadvantages of general artificial neural network (ANN), such as it is not easy to converge, liable to trap in partial minimum and unable to optimize globally, and the generalization of the model is not good, etc. The SVM model ensured the forecasting is optimized globally. Subsequently, examples of electricity load data from Hebei Province of China are used to illustrate the performance of the proposed model. The empirical results reveal that the proposed model outperforms the general artificial neural network model, and the forecasting accuracy improved effectively. Therefore, the model provides a promising arithmetic to forecasting electricity load in power industry.

The molecular cation CO+ is a very important transient molecular radical, and the spectra of the ion has been investigated by numerous researchers. Optical-heterodyne-magnetic-rotation-enhanced velocity modulation spectroscopy(OH-MR-VMS) was employed to measure the comet-tail system (A2 pi(i)-X2 sigma+) of 12C16O+ molecular ion. The vibrational rotation absorption spectra wereobserved in the near-infrared region, including three bands of (0, 3), (1, 4) and (3, 6). A set of precise molecular constants for the A2 pi(i) (v' = 0, 1, 3) were determined using the least-squares fit. This experiment has further proved that OH-MR-VMS is very valuable in measuring absorption spectra of molecular ions.

The CN radical was produced by Penning AC discharge of the mixture of trace acetonitrile (36 Pa) and helium (660 Pa) and the ro-vibrational spectra were measured by optical heterodyne magnetic rotation enhanced concentration modulation spectroscopy in the range of 16 850-17 480 cm(-1). 138 lines and 118 lines were assigned to the (6, 1) and (7, 2) bands in red system A 2IIi-X 2sigma+ of CN respectively, while others were due to (8, 3) band in CN red system and C2 Swan band system. More accurate molecular constants of A 2IIi (v = 6, 7) state and perturbation parameters zeta and eta between A and X states were derived based on nonlinear least-square fitting, individually, by diagonalizing the effective Hamiltonian matrix involving the perturbation elements of two electronical states and the standard deviation of fitting was less than the experimental uncertainty 0.007 cm(-1), which implied the accuracy of our results.

In this paper, a simple and applied approach was presented, which can automatically locate pupils. On the basis of skin detection of human face, it combines such techniques as edge extraction and geometrical features to confirm the coarse eye regions with ways of gray integration projection, region combination and LAT to fix on the precise location of pupils. By using this method, one could attain the accurate localization of eyes in color images, so it is suitable for processing identification photos.