Symmetry of Lagrangians of nonholonomic systems of non-Chetaev’s type

This paper studies the symmetry of Lagrangians of nonholonomic systems of non-Chetaev's type. First, the definition and the criterion of the symmetry of the system are given. Secondly, it obtains the condition under which there exists a conserved quantity and the form of the conserved quantity. Finally, an example is shown to illustrate the application of the result.     

Teleportation of an arbitrary mixture of diagonal states of multiqudit

This paper proposes a scheme to teleport an arbitrary mixture of diagonal states of multiqutrit via classical correlation and classical communication. To teleport an arbitrary mixture of diagonal states of N qutrits, N classically correlated pairs of two qutrits are used as channel. The sender （Alice） makes Fourier transform and conditional gate （i.e., XOR（3） gate） on her qutrits and does measurement in appropriate computation bases. Then she sends N ctrits to the receiver （Bob）. Based on the received information, Bob performs the corresponding unitary transformation on his qutrits and obtains the teleported state. Teleportation of an arbitrary mixture of diagonal states of multiqudit is also discussed.     

Influence of Self-Interaction ofσ Meson to the Equation of State of Nuclear Matter

In the relativistic σ-ωmodel, the influence of the parameters in self-interaction of a meson to the equation of state of normal nuclear matter, especially, to incompressibility, effective mass, and coupling constants, is studied in detail. We find that these parameters have an intense relationship to the property of nuclear matter. At the same time , we study the relation between the binding energy and pressure of relativestic △-resonance nuclear matter and temperature using using above results in the relativistic σ-ω-π model,and it is interesting to compare it to our prior work. In all these studies, the vacuum fluctuation on nucleon, △-isobar, and σmeson is considered.     

Analysis of the causes of formation of negative loss factors

I-IatroductionStatisticalEnergyAnalysis(SEA)isakindofeffective,simpleanddirectapproachforan-alyzingvibrationandsound,andithasbeenfoundwidelyapplicationsinanalysisofmechanicalnoiseandvibrationcolltrolsince198osl1-4].However,forgeneralindustrialmachineswhichalwayconsistofcomPlexandheaVystructures,thedeterminationmethodsofSEAparametersintheclassicalSEAtheoryareinapplicable[5]because:(1)SEAparametersofthesekindsofstructuresaredifficulttoobtainfromthetheory(2)theconditionofconservativeandweak…     

Measurement-device-independent quantum key distribution of multiple degrees of freedom of a single photon

Measurement-device-independent quantum key distribution(MDI-QKD)provides us a powerful approach to resist all attacks at detection side.Besides the unconditional security,people also seek for high key generation rate,but MDI-QKD has relatively low key generation rate.In this paper,we provide an efficient approach to increase the key generation rate of MDI-QKD by adopting multiple degrees of freedom(DOFs)of single photons to generate keys.Compared with other high-dimension MDI-QKD protocols encoding in one DOF,our protocol is more flexible,for our protocol generating keys in independent subsystems and the detection failure or error in a DOF not affecting the information encoding in other DOFs.Based on above features,our MDI-QKD protocol may have potential application in future quantum comniunication field.     

Department of Physics Renmin University of China

Location Renmin University of China 59 Zhongguancun Ave.,Beijing 100872,China Futher Information:http:www.phys.ruc.edu.cn/Location Renmin University is one of top universities in China.The Department of Physics was founded in the fall of 2005.The Department has 35 full-time faculty members,including 20 professors,12 associate professors,and 3 lecturers.Their orientation is high-quality research combined with physics instruction across the full spectrum of core subjects.The activities of the department are designed to exploit the intrinsic synergy of innovative research teaching and academic exchanges in physics and related disciplines all of which are pursued at an internationally recognized standard.     

Improvement of Synchronizability of Scale-Free Networks

We investigate the factors that affect synchronizability of coupled oscillators on scale-free networks. Using the memory Tabu search （MTS） algorithm, we improve the eigen-ratio Q of a coupling matrix by edge intercrossing. The numerical results show that the synchronizatlon-improved scale-free networks should have distinctive both small average distance and larger clustering coefficient, which are consistent with some real-world networks. Moreover, the synchronizability-improved networks demonstrate the disassortative coefficient.     

Analysis of Frequency Spectrum of Laser-Induced Vibration of Microbeam Resonators

The vibration phenomenon during pulsed laser heating of micro-beams is investigated. The beam is made of silicon and is heated by a laser pulse with a non-Gaussian temporal profile and with an ultrashort pulse duration of 2ps, which incites vibration due to the thermoelastic damping effect. This coupled thermoelastic problem is solved using an analytical-numerical technique based on the Laplace transformation. The damping ratio and resonant frequency shift ratio of beams due to the air damping effect and the thermoelastic damping effect are also examined and discussed.     

Density functional theory study of the interaction of H2 with pure and Ti-doped WO3 (002) surfaces

Density functional theory (DFT) calculations are conducted to explore the interaction of H₂ with pure and Ti-doped WO₃ (002) surfaces. Four top adsorption models of H₂ on pure and Ti-doped WO₃ (002) surfaces are investigated respectively, they are adsorption on bridging oxygen O_1c, absorption on plane oxygen O_2c, absorption on 5-fold W_5c (Ti), and absorption on 6-fold W_6c. The most stable and H₂ possible adsorption structure in the pure surface is H-end oriented to the surface plane oxygen O_2c site, while the favourable adsorption sites for H₂ in a Ti-doped surface is not only an O_2c site but also a W_6c site. The adsorption energy, the Fermi energy level E_F, and the electronic population are investigated and the H₂-sensing mechanism of a pure-doped WO₃ (002) surface is revealed theoretically: the theoretical results are in good accordance with our existing experimental results. By comparing the above three terms, it is found that Ti doping can obviously enhance the adsorption of H₂. It can be predicted that the method of Ti-doped into a WO₃ thin film is an effective way to improve WO₃ sensor sensitivity to H₂ gas.     

Ab-initio density functional theory study of a WO3 NH3-sensing mechanism

WO 3 bulk and various surfaces are studied by an ab-initio density functional theory technique.The band structures and electronic density states of WO 3 bulk are investigated.The surface energies of different WO 3 surfaces are compared and then the (002) surface with minimum energy is computed for its NH 3 sensing mechanism which explains the results in the experiments.Three adsorption sites are considered.According to the comparisons of the energy and the charge change between before and after adsorption in the optimal adsorption site O 1c,the NH 3 sensing mechanism is obtained.     

Density functional theory study of the NO2-sensing mechanism on a WO3 (0 0 1) surface: the role of surface oxygen vacancies in the formation of NO and NO3

The trapping and detection of nitrogen oxide with tungsten trioxide has become a popular research topic in recent years. Knowledge of the complete reaction mechanism for nitrogen oxide adsorption is necessary to improve detector performance. In this work, we used density functional theory (DFT) calculations to study the adsorption characteristics and electron transfer of nitrogen dioxide on an oxygen-deficient monoclinic WO₃ (0 0 1) surface. We observed different reactions of NO₂ on slabs with different O- and WO-terminated WO₃ (0 0 1) surfaces with oxygen vacancies. Our calculations show that the bridging oxygen atom on an oxygen defect on an O-terminated WO₃ (0 0 1) surface is the active site where an NO₂ molecule is oxidised into nitrate and is adsorbed onto the surface. On a WO-terminated (0 0 1) surface, one of the oxygen atoms from the NO₂ molecule fills the oxygen vacancy, and the resulting NO fragment is adsorbed onto a W atom. Both of these adsorption models can cause an increase in the electrical resistance of WO₃. We also calculated the adsorption energies of NO₂ on slabs with different oxygen-deficient WO₃ surfaces.     

超高温度系数V0.97W0.03 O2多晶薄膜的制备研究

将V₂O₅粉体与WO₃粉体均匀混合并压制成靶，用离子束增强沉积加后退火技术在SiO₂衬底上制备掺钨VO₂多晶薄膜.X射线衍射表明，薄膜取向单一，为VO₂结构的［002］相,晶格参数d比VO₂粉晶增大约0.34%；薄膜从半导体相向金属相转变的相变温度约28；室温(300 K)时的电阻-温度系数(TCR)可大于10%/K，是目前红外热成像薄膜TCR的四倍.W离子的半径大于V离子的半径，W的掺入在薄膜中引入了张应力,使薄膜相变温度降低到室温附近，是IBED V_0.97W_0.03O₂薄膜的室温电阻温度系数提高的原因. 关键词： 二氧化钒薄膜 薄膜掺杂 离子束增强沉积     

Porous WO3 from anodized sputtered tungsten thin films for NO2 detection

In this paper, porous WO₃ films were prepared by anodic oxidation of metallic tungsten (W) films deposited on alumina substrates. The structural and morphological properties of the porous WO₃ films were investigated using field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD). A large number of cracks appeared on the surface of films after anodization, which makes the films porous. The porous WO₃ sensors achieved their maximum response values to NO₂ at a low operating temperature of 150 °C. The porous WO₃ sensors showed high response values, great stability and fast response-recovery characteristics to different concentration of NO₂ gas due to the high specific surface area and special structural and morphological properties.     

Preparation of WO3 nanoparticles and application to NO2 sensor

WO₃ nanoparticles were prepared by evaporating tungsten filament under a low pressure of oxygen gas, namely, by a gas evaporation method. The crystal structure, morphology, and NO₂ gas sensing properties of WO₃ nanoparticles deposited under various oxygen pressures and annealed at different temperatures were investigated. The particles obtained were identified as monoclinic WO₃. The particle size increased with increasing oxygen pressure and with increasing annealing temperature. The sensitivity increased with decreasing particle size, irrespective of the oxygen pressure during deposition and annealing temperature. The highest sensitivity of 4700 to NO₂ at 1 ppm observed in this study was measured at a relatively low operating temperature of 50 °C; this sensitivity was observed for a sensor made of particles as small as 36 nm.     

Effect of Ti doping on Ta2O5 stacks with Ru and Al gates

The Ti-doped Ta₂O₅ thin films (<10 nm) obtained by rf sputtering are studied with respect to their composition, dielectric and electrical properties. The incorporation of Ti is performed by two methods - a surface doping, where a thin Ti layer is deposited on the top of Ta₂O₅ and a bulk doping where the Ti layer is sandwiched between two layers of Ta₂O₅. The effect of the process parameters (the method and level of doping) on the elemental distribution in-depth of the films is investigated by the time of flight secondary ion mass spectroscopy (ToF-SIMS). The Ti and Ta₂O₅ are intermixed throughout the whole thickness but the layers are very inhomogeneous. Two sub-layers exist in all the samples — a near interfacial region which is a mixture of Ta-, Ti-, Si-oxides as well as TaSiO, and an upper Ti-doped Ta₂O₅ sub-layer. For both methods of doping, Ti tends to pile-up at the Si interface. The electrical characterisation is performed on capacitors with Al- and Ru-gate electrodes. The two types of MIS structures exhibit distinctly different electrical behavior: the Ru gate provides higher dielectric permittivity while the stacks with Al electrode are better in terms of leakage currents. The specific metal-dielectric reactions and metal-induced electrically active defects for each metal electrode/high-k dielectric stack define its particular electrical behavior. It is demonstrated that the Ti doping of Ta₂O₅ is a way of remarkable improvement of leakage characteristics (the current reduction with more than four orders of magnitude as compared with undoped Ta₂O₅) of Ru-gated capacitors which originates from Ti induced suppression of the oxygen vacancy related defects.     

Non-catalytic and substrate-free method to titania-doped W18O49 nanorods: growth, characterizations, and electro-optical properties

In the present study, titania-doped (Ti-doped) W₁₈O₄₉ nanorods have been prepared using a modified plasma arc gas condensation technique. Characterizations by field-emission gun scanning electron microscopy, X-ray powder diffraction, high-resolution transmission electron microscopy and high-resolution X-ray photoelectron spectroscopy indicate that the as-prepared nanorods with a single-crystalline monoclinic W₁₈O₄₉ phase are of 20–100 nm in diameter and several micrometers in length. The Raman peaks of the Ti-doped W₁₈O₄₉ nanorods show a red-shift Raman peaks, and an additional green-emission peak at 497 nm is observed in the photoluminescence (PL) spectrum compared to pure W₁₈O₄₉ nanorods. Field-emission (FE) measurements reveal that the turn-on (E _to) and threshold (E _thr) voltages of the Ti-doped W₁₈O₄₉ nanorods are 2.2 and 3.4 V/μm, respectively. A vapor–solid process that does not involve the use of catalyst is proposed for the nanorod growth mechanism. Experimental results show that the additional defects resulting from titania doping are responsible for the enhancement of the optical and FE properties of the pure W₁₈O₄₉ nanorods.     

Doping investigations of the spin-Peierls-system CuGeO3

We investigated the effect of doping CuGeO₃ with Zn, Ni, Mn and Mg on the Cu-site, and Al, Si, Ga, As, In, Sn, Sb and Ti on the Ge-site. The lattice parameters show a linear dependence on doping. The spin-Peierls (SP) transition temperature T_SP decreases linearly with increasing substitution, the slope depending on the dopant. For increasing Zn-content, a Néel-like groundstate which exhibits spin-flop-behaviour appears after the disappearence of the SP-ground-state. Si-and Ti-doped samples exhibit a similar phase in co-existence with the SP-groundstate.     

A photoelectron spectroscopic observation of iron surfaces exposed to N2, N2O,NO, NO2 and air at 200 torr or 1 atm

Photoelectron spectra from core levels are presented for adsorption of nitrogen-containing gases at 200 torr or 1 atm on iron surfaces. Assignments of each band and the adsorption process are discussed. On the substrate at normal temperature, each gas forms nitride and nitrogen oxide groups (NO, NO₂ and NO₃) which appear at 398.6, 400.0, 404.5 and 407.1 eV, respectively. The relative intensifies of each species depend on the gases adsorbed. NO and NO₂ are considered to dissociate on the surface and the oxygen atom adsorb preferentially. The oxygen on the surface can be considered to contribute to the formation of each surface ligand.