竖炉电振给料机长寿改造

本文对电磁振动给料机盘面变形进行了观察分析,根据竖炉生产的要求,通过试验采用了耐热耐磨CrMn铸钢代替锰板材料制造电振盘面。

Low phase noise LC VCO design in CMOS technology

This paper presents the design and the experimental measurements of two complementary metal-oxide-semiconductor (CMOS) LC-tuned voltage controlled oscillators (VCO) implemented in a 0.18 μm 6-metal-layer mixed-signal/RF CMOS technology. The design methodologies and approaches for the optimization of the ICs are presented. The first design is optimized for mixed-signal transistor, oscillated at 2.64 GHz with a phase noise of -93.5 dBc/Hz at 500 kHz offset. The second one optimized for RF transistor, using the same architecture, oscillated at 2.61 GHz with a phase noise of -95.8 dBc/Hz at 500 kHz offset. Under a 2 V supply, the power dissipation is 8 mW, and the maximum buffered output power for mixed-signal and RF transistor are -7 dBm and -5.4 dBm, respectively. Both kinds of oscillators make use of on-chip components only, allowing for simple and robust integration.

Electromagnetic simulation and experimental analysis of microwave heaters for asphalt pavements

In order to study the thermoelectric efficiency of microwave heating and reproduction of asphalt pavements and the uniformity of reproduction temperature distribution, a waveguide excitation cavity is designed and applied to the structural design of a microwave heater. The structural sizes of the incentive cavities are determined based on the waveguide transmission line theory. Using IE3D software, electromagnetic simulations are respectively carried out in four different situations, including the distances between the magnetron probes （antennas） and a short-circuit board, different horn electric lengths and aperture sizes, different dielectric properties of the asphalt mixture, and the distances between the asphalt surface and the mouth cavity. The results show that, when the distance between the magnetron probe and the short-circuit board is 32.5 ram, it is the best installation site; reduction of aerial length is the main factor in improving the heating uniformity. When the aggregate is limestone, the best heating effect can be produced. Maximum radiation efficiency can be realized by adjusting the space between the heater radiation port and the asphalt pavement. The experimental results of asphalt mixture heating in four different situations have a substantial agreement with the simulation results, which confirms that the developed microwave heater can achieve better impedance matching, thus improving the quality and efficiency of heating regeneration.

A novel ring vibrating gyroscope based on side piezo-electrodes

Solid-state wave gyroscope is one kind of high-performance vibrating gyroscopes. The present work develops a new type of solid-state wave gyroscope—a ring vibrating gyroscope driven by piezo-electrodes located on the sidewall of the structure. It has advantages of large vibrating amplitude, high energy conversion efficiency and compact structure. The working principle of the piezoelectric ring vibrating gyroscope is based on the inertia effect of the standing wave in the axisymmetric resonator caused by Coriolis force. The finite element method(FEM) analysis has been implemented to characterize the ring type resonator. The prototypal gyroscope was manufactured and has been trimmed by mechanical way. The harmonic response of the ring vibrating gyroscope has been tested. The resonating frequency of the ring type resonator is 3715.6 Hz and the frequency split of the two working modes before trimming was about 5 Hz and was reduced to sub-0.01 Hz after trimming procedure. The Q-factor of the ring type resonator was 2504. Then, the turntable experiment was implemented. The measured scale factor k is 9.24 m V/[(°)·s] and the full scale range of the gyroscope is larger than ±300(°)/s.

Effects of electromagnetic vibration on the structure and mechanical properties of Al-6%Si alloy during directional solidification

The effects of electromagnetic vibration on the grain refinement in directional solid- ification were investigated. It was found that the electromagnetic vibration applied in the melt not only can refine grains remarkably but also can enhance both tensile strength and ductility values of Al-6%Si alloy. SEM graphs show that coarse dendrite structure was broken up into a somewhat globular structure, and the morphology of eutectic silicon was changed from flaky to fibrous under electromagnetic vibration treatment. The refine mechanism under electromagnetic vibration was discussed.

Structural and Vibrational Study of PCBM

The 1-（3-methoxycarbonyl） propyl-1-phenyl-（6,6）C61 （also called PCBM） is a C60 derivative widely used as an electron-acceptor in organic solar cells. To date, all the infrared spectra reported are experimental, mainly because of the calculations needed to study these structures are highly time-consuming. In this report we address for the first time the infrared spectrum calculation of PCBM with Cs symmetry by using the PW91/dnp level as implemented in the Dmol3 code. In this calculation we have found two intense peaks in the IR spectrum, that agree fairly with the 1187 and 1787 cm^-1 measured experimentally.

The influence of the crystalline nature of nano-metal oxides on their antibacterial and toxicity properties

The antibacterial properties of nano-metal oxides （ZnO, CuO） are based on the formation of reactive oxygen species （ROS）. This work reveals that the antibacterial properties of these nano-metal oxides are strongly dependent on their crystalline structure. The antibacterial activity of the nanooxides was tested against four types of bacteria that commonly cause nosocomial infections. The sonochemical method was applied not only for synthesis of nanooxides but also to their coating on textiles. The antibacterial properties of textiles coated with commercial and sonochemically prepared nano-metal oxides were evaluated and compared. The toxicity was evaluated on human lung cells and amphibian embryos, as representative models for inhalation and aquatic toxicology. The sonochemically prepared metal nanooxides are better antimicrobials than commercially available metal oxides with the same particle size range. It was found that the crystallites which have more defects and less organized structure are more toxic. The formation of ROS was studied by electron spin resonance （ESR） measurements for both the sonochemically prepared and commercial samples of ZnO/CuO nanoparticles. A significant increase in the production of radical species was found in the more defective, sonochemically prepared samples, as compared to the commercial ones. Since modulation of the nanoparticle defects influenced their toxicity, the possibility of engineering safer nano-antibacterials is indicated.

Strain-induced direct-indirect bandgap transition and phonon modulation in monolayer WS2

In situ strain photoluminescence （PL） and Raman spectroscopy have been employed to exploit the evolutions of the electronic band structure and lattice vibrational responses of chemical vapor deposition （CVD）-grown monolayer tungsten disulphide （WS2） under uniaxial tensile strain. Observable broadening and appearance of an extra small feature at the longer-wavelength side shoulder of the PL peak occur under 2.5% strain, which could indicate the direct-indirect bandgap transition and is further confirmed by our density-functional-theory calculations. As the strain increases further, the spectral weight of the indirect transition gradually increases. Over the entire strain range, with the increase of the strain, the light emissions corresponding to each optical transition, such as the direct bandgap transition （K-K） and indirect bandgap transition （F-K, ≥2.5%）, exhibit a monotonous linear redshift. In addition, the binding energy of the indirect transition is found to be larger than that of the direct transition, and the slight lowering of the trion dissociation energy with increasing strain is observed. The strain was used to modulate not only the electronic band structure but also the lattice vibrations. The softening and splitting of the in-plane E＇ mode is observed under uniaxial tensile strain, and polarization-dependent Raman spectroscopy confirms the observed zigzag-oriented edge of WS2 grown by CVD in previous studies. These findings enrich our understanding of the strained states of monolayer transition-metal dichalcogenide （TMD） materials and lay a foundation for developing applications exploiting their strain-dependent optical properties, including the strain detection and light-emission modulation of such emerging two-dimensional TMDs.

Suppression of vortex-induced vibration of a circular cylinder by Lorentz force

The electro-magnetic control of vortex-induced vibration (VIV) of a circular cylinder is investigated numerically in the exponential-polar coordinates attached on the moving cylinder for Re=150 in the paper. Compared with the fixed cylinder, the vibration of cylinder leads to the shift of stagnation point, the shear layer strength and the inertial force, which affects the hydrodynamic forces on the cylinder. The effects of the instantaneous wake geometries and the corresponding cylinder motion on the hydrodynamic forces for one entire period of vortex shed are discussed in the drag-lift phase diagram. The Lorentz force for controlling the vibration cylinder is classified into the field Lorentz force and the wall Lorentz force. The field Lorentz force decreases the lift oscillation, and in turn, suppresses the VIV, whereas the wall Lorentz force has no effect on the lift.

Robust control of exciting force for vibration control system with multi-exciters

Due to the dynamical character of electromagnetic exciter and the coupling between structure and exciter(s),the actual output force acting on the structure is usually not equal to the exact value that is supposed to be,especially when multi-exciters are used as actuators to precisely actuate large flexible structure.It is necessary to consider these effects to ensure the force generated by each exciter is the same as required.In this paper,a robust control method is proposed for the multi-input and multi-output(MIMO)structural vibration control system to trace the target actuating force of each exciter.A special signal is designed and put into the coupled mul-ti-exciter-structure system,and the input and output signals of the system are used to build a dynamic model involving both the dynamical characters of the exciters and the structure using the subspace identification method.Considering the uncertainty factors of the multi-exciter/structure system,an H-infinity robust controller is designed to decouple the coupling between structure and exciters based on the identified system model.A MIMO vibration control system combined with a flexible plate and three electromagnetic exciters is adopted to demonstrate the proposed method,both numerical simulation and model experiments showing that the output force of each exciter can trace its target force accurately within the requested frequency band.

Controlling structural vibrations in wind turbines by constructing function V

For a variable speed large scale wind turbine, the vibration issues become a key problem that cannot be ignored in the turbine＇s life cycle. Wind turbine tower vibration will cause superfluous mechanical loads. To resolve the vibration issue, a method for constructng the energy function V is proposed to meet the demands of safe operation. The Lyapunov theorem has been em- bedded in a wind turbine control algorithm, proving the theoretical feasibility of stability control based on function V. Accord- ing to an analysis of this complex nonlinear model for the wind turbine, the general method of constructing an energy function suitable for a wind turbine is presented explicitly. The feasibility of applying an energy function to wind turbine vibration con- trol is verified experimentally using a 3.0-MW direct drive wind turbine model. The experimental results indicate that the dy- namic performance of the tested wind turbine model with energy function control is significantly better than that of the uncon- trolled structure in terms of the reduction of nacelle acceleration, velocity, and displacement response.

Structural, Spectroscopic and Vibrational Properties for Low-Lying Electronic States of LiCl

A multireference configuration interaction （MRCI） study has been carried out on the LiCl molecule. The potential energy has been calculated over a wide range of internuclear separation for the 21 low-lying electronic states of the LiCl molecule dissociating into Li （^2S, ^2p, ^3S）＋Cl （^2p）. The （4）^1∑^＋, （3）∏, 1-3^3∑^＋, 1-3^3∏, 1,3Δ, ^1,3∑^-, （5）^1∑^＋,（4）^3∑^＋, （4）^3∏, （4）^3∏ excited states are studied for the first time in theory. Molecular spectroscopic constants .（Re, De,ωe, ωeΧe,Be and αe） have been derived for the 9 bound states （X^1∑^＋, （3）^1∑^＋, （2）^3∑^＋, ^1,3Δ, ^1,3∑^-, （4）^∏, （4）^3∏） with a regular shape, and the spectroscopic constants of ground states X^1 ∑^＋ are in good agreement with available experimental and theoretical values. The relative differences between experimental values and our values for Re, De, ωe, ωeΧe, Be and α3 are 1.02%, 0.60%, 1.72%, 9.46%, 2.0%, and 0.75%, respectively. Moreover, vibrational levels of 9 bound states, which have not been investigated experimentally, are computed.

Structure characterization,magnetic and photoluminescence properties of Mn doped ZnS nanocrystalline

Wurzite ZnS:Mn nanorods are synthesized via a solvothermal method by using ethylenediamine and water as mixed solvent.The diameters of the nanorods increase and the lengths decrease with the Mn concentration.High resolution transmission electron microscopic images illustrate that a few cubic ZnS:Mn nanoparticles arise along with hexagonal nanorods on high Mn concentration.The samples set off yellow-orange emission at 590 nm,characteristic of 4 T→ 6 A 1 transition of Mn 2+ at T d symmetry in ZnS.Electron spin resonance spectrum of the nanorods shows that high Mn concentrations produce a broad envelope,whereas six-line hyperfine appears for lower Mn concentrations.These results together with the magnetization curves indicate that all the ZnS:Mn samples are paramagnetic even down to 4 K,which suggests that the ZnS:Mn is not suitable for dilute magnetic semiconductor.

High-lying excited states in ^10Be from the ^9Be(^9Be,^10Be)^8Be reaction

A transfer-reaction experiment of ~9Be(~9Be,^(10)Be)~8Be was performed at a beam energy of 45 Me V.Excited states in ^(10)Be up to 18.80 Me V are produced using missing mass and invariant mass methods.Most of the observed high-lying resonant states,reconstructed from theα+~6He and t+~7Li decay channels,agree with the previously reported results.In addition,two new resonances at 15.6 and 18.8 Me V are identified from the present measurement.The 18.55 Me V state is found to decay into both the t + ~7Lig:s: and t + ~7Li?(0.478 MeV) channels, with a relative branching ratio of 0:93 ± 0:33. Further theoretical investigations are encouraged to interpret this new information on cluster structure in neutron-rich light nuclei.