The First Student International Olympiad on Mechanism and Machine SciencemThe Challenge in MMS Education

One of important tasks of IFToMM is attraction of youth attention to profound study of mechanism and machine science. To solve this task, special youth programs are developed, various discounts are provided for young researchers＇ participation in IFToMM congresses and conferences. A new progressive type of such an activity is organization of Student International Olympiads （SIO） on Mechanism and Machine Science （MMS） which can be considered a new advantageous form of MMS study. The paper describes experiences of organization and holding the first SIO MMS, which took place on April 19-21,2011 in Izhevsk （Russia） at Izhevsk State Technical University.

High-tech Enterprise—Chinese Academy of Agricultural Mechanization Sciences

Chinese Academy Of Agricultural MechanizationSciences(CAAMS)is the largest research organizationwith the strongest innovation ability engaged infundamental,application sciences with multiple disciplines,comprehensiveness and gives priority to R&D on modernagriculture equipment while facing the needs of agriculture,countryside and farmers.Since the establishment of CAAMS40 years ago,it coordinated the related Ministries andCommissions of our country to finish researching andmanufacturing over 3000 kinds of agricultural machineries of9 categories,gained more than 2000 scientific and

Preparation of High-Density Nanocrystalline Bulk Selenium by Rapid Compressing of Melt

The melt＇s solidification behavior of elemental selenium is investigated by a series of experiments including rapid compressing to 2.8 and 3.5 GPa within 20ms respectively, slow compressing to 2.8 GPa for 20 min and natural cooling at ambient pressure. Based on the x-ray diffraction, scanning electron microscope and transmission electron microscope results of the recovered samples, it is clearly shown that homogenous nanostructures are formed only by the rapid compression processes, and that the average crystal sizes are about 18.7 and 19.0 nm in the samples recovered from 2.8 and 3.5 GPa, respectively. The relative density of the nanocrystalline bulk reaches 98.17% of the theoretical value. It is suggested that rapid compression could induce pervasive nucleation and restrain grain growth during the solidification, which is related to fast supercooling, higher viscosity of the melt and lower diffusivity of atoms under high pressure.

Synthesis and Properties of Magnetic Composites of Carbon Nanotubes/Fe Nanoparticle

Magnetic composites of carbon nanotubes （CNTs） are synthesized by the in situ catalytic decomposition of benzene at temperatures as low as 400℃ over Fe nanoparticles （mean grain size = 26 nm） produced by sol-gel fabrication and hydrogen reduction. The yield of CNT composite is up to about 3025% in a run of 6 h. FE- SEM and HRTEM investigations reveal that one-dimensional carbon species are produced in a large quantity. A relatively high value of magnetization is observed for the composite due to the encapsulation of ferromagnetic Fe3 C and/or α-Fe. The method is suitable for the mass-production of CNT composites that contain magnetic nanoparticles.

A Unified Guide to Two Opposite Size Effects in Nano Elastic Materials

The microstructural variation near surface of nano elastic materials is analyzed based on different potentials. The atomic/molecular mechanism underlying the variation and its effect on elastic modulus are such that the nature of long-range interactions （attractive or repulsive） in the atomic/molecular potentials essentially governs the variation near surface （looser or tighter） and results in two opposite size effects （decreasing or increasing modulus） with decreasing size.

Production of ZnO Nanobelts and Meso-Scale Study of Mechanical Properties

We investigate a peculiar phenomenon by processing ZnO nanobelts with an atomic force microscope （AFM）. In the contact mode of AFM, peculiar bending occurs in meso-scale when the nanobelt is applied with force in lateral direction. We study the mechanical properties of ZnO nanobelts under the influence of small size effect, with finite element analysis and mathematical analysis by means of Matlab. Based on this abnormal effect, a novel measuring method is proposed, which allows the surface morphology and surface properties to be characterized at the same time.

Growth of Pure Zinc Blende GaAs Nanowires： Effect of Size and Density of Au Nanoparticles

Pure zinc blende GaAs nanowires were grown by metal organic chemical vapor deposition on GaAs（111）B substrates via Au catalyzed vapor-liquid-solid mechanism. The diameter, size distribution, and density of Au particles can be changed by varying the Au film thickness. We find that the grown nanowires are of rod-like shapes and pure zinc blende structure; moreover, the growth rate depends on the density of Au particles and it is independent of its diameters. It can be concluded that the nanowire was grown with main contributions from the direct impingement of vapor species onto the Au-Ga droplets and contributions from adatom diffusion can be negligible. The results indicate that the droplet acts as a catalyst rather than an adatom collector.

Raman Spectrum of Epitaxial Graphene on SiC （0001） by Pulsed Electron Irradiation

We report new Raman features of epitaxial graphene （EG） on Si-face 4H-SiC prepared by pulsed electron irradiation （PEI）. With increasing graphene layers, frequencies of G and 2D peaks show blue-shifts and approach those of bulk highly-oriented pyrolytic graphite. It is indicated that the EG is slightly tension strained and tends to be strain-free. Meanwhile, single Lorentzian line shapes are well fitted to the 2D peaks of EG on SiC（O001） and their full widths at half maximum decrease with the increasing graphene layers, which indicates that the multilayer EG on Si-face can also contain turbostratic stacking by our PEI route instead of only AB Bernal stacking by a traditional thermal annealing method. It is worth noting that the stacking style plays an important role on the charge carrier mobility. Therefore our findings will be a candidate for growing quality graphene with high carrier mobility both on the Si- and C-terminated SiC substrate. Mechanisms behind the features are studied and discussed.

Effect of In Composition on Two-Dimensional Electron Gas in Wurtzite AlGaN/InGaN Heterostructures

The effect of In composition on two-dimensional electron gas in wurtzite AlGaN/InGaN heterostructures is theoretically investigated. The sheet carrier density is shown to increase nearly linearly with In mole fraction x, due to the increase in the polarization charge at the AlGaN/InGaN interface. The electron sheet density is enhanced with the doping in the AlGaN layer. The sheet carrier density is as high as 3.7×1013 cm^-2 at the donor density of 10×1018 cm^-3 for the HEMT structure with x=0.3. The contribution of additional donor density on the electron sheet density is nearly independent of the In mole fraction.

Entanglement Purification for Mixed Entangled Quantum Dot States via Superconducing Transmission Line Resonators

An entanglement purification protocol for mixed entangled states is presented via double quantum dot molecules inside a superconducing transmission line resonator （TLR）. In the current scenario, coupling for arbitrary double quantum dot molecules can be tuned via the TLR in the large detuning region by controlling the qubit level splitting. The TLR is always empty and only virtually excited, so the interaction is insensitive to both the TLR decay and thermal field. Discussion about the feasibility of our scheme shows that the entanglement purification can be implemented with high fidelity and successful probability.

Raman Investigation of Sodium Titanate Nanotubes under Hydrostatic Pressures up to 26.9GPa

High pressure behavior of sodium titanate nanotubes （Na2Ti2O5） is investigated by Raman spectroscopy in a diamond anvil cell （DAC） at room temperature. The two pressure-induced irreversible phase transitions are observed under the given pressure. One occurs at about 4.2 GPa accompanied with a new Raman peak emerging at 834 cm-1 which results from the lattice distortion of the Ti-O network in titanate nanotubes. It can be can be assigned to Ti-O lattice vibrations within lepidocrocite-type （H0.7Ti1.825V0.175O4＆#12539;H2O）TiO6 octahedral host layers with V being vacancy. The structure of the nanotubes transforms to orthorhombic lepidocrocite structure. Another amorphous phase transition occurs at 16.7 GPa. This phase transition is induced by the collapse of titanate nanotubes. All the Raman bands shift toward higher wavenumbers with a pressure dependence ranging from 1.58-5.6 cm-1/GPa.

Influence of Oxygen Pressure on Structural and Sensing Properties of β-Ga2O3 Nanomaterial by Thermal Evaporation

We prepare the gallium oxide （β-Ga2O3） nanomaterials from gallium and oxygen by thermal evaporation in the argon atmosphere and research their oxygen sensing under UV illumination with different oxygen pressures. X-ray diffraction reveals that the synthesized product is monoclinic gallium oxide, it is further confirmed by electron diffraction of transmission electron microscope, and its morphology through the observation using scanning electron microscope reveals thatβ-Ga2O3 nanobelts with a breadth less than lOOnm and length of severai micrometers are synthesized under low oxygen pressure, while the nano/microbelts are synthesized under high oxygen pressure. Room-temperature oxygen sensing is tested under at 254 nm illumination and it is found that the current decreases quickly first and then slowly with oxygen pressure from low to high.

Thermal Properties of Poly（vinyl chloride-co-vinyl acetate-co-2-hydroxypropyl acrylate） （PVVH） Polymer and Its Application in ZnO Based Nanogenerators ：

A novel piezoelectricity based nano energy conversion device using vertically aligned ZnO nanowires/PVVH matrix as the working unit is proposed. Thermal energy is converted to electricity via the interaction of the PVVH polymer and ZnO nanowires. The thermal properties of PVVH ave studied using Raman spectroscopy under different temperatures. The results show that the structure of PVVH is sensitive to fluctuations of the environmental temperatures. With the increasing temperature, PVVH tends to be crystallized and stress can be developed inside the polymer. The stress is responsible for the deformation and voltage generation of the ZnO nanowires.

Electromechanical Behavior of Interdigitated SiO2 Cantilever Arrays

Bending and first flexural mode vibration behavior of electrostatic actuated nanometer-sized interdigitated cantilever arrays are characterized under vacuum conditions. The pull-in＇＇ effect in dc driving and the hard spring effect＇＇ in ac driving are observed. A mass sensitivity of 20 fg is expected for our devices due to the ultra-small mass of the arm and relative high Q factor. The mass-spring lump model combined with Green＇s function method is used to fit the dc driving behaviors including the pull-in voltage. For the ac driving case, the polynomial expansion of the capacitive force is used in the model. The successfully fittings of the pull-in voltage and the hard spring effect prove that our simulation method could be used for guiding the geometrical design of cantilever-based sensors.

Population Swap of a Pair of Quantum Dots Coupling to a Plasmonic Nanocavity

We theoretically design a single-mode plasmonic ring nanocavity. Based on the plasmonic cavity, the exciton dynamics between two identical quantum dots （QD-p, QD-q） coupled to the nanocavity are investigated. It is shown that the coupling factors gi （i = p, q） between QD-i and surface plasmons are both equal to 12.53meV in our model and exeiton population swap between the two QDs can be realized. The periods and amplitudes of population oscillations can be modified by the coupling factors. Our results may have potential applications in quantum information and quantum computation on a chip.

Creating technical heritage object replicas in a virtual environment

The paper presents innovative informatics methods for creating virtual technical heritage replicas, which are of significant scientific and practical importance not only to researchers but to the public in general. By performing 3D modeling and animation of aircrafts, spaceships, architectural-engineering buildings, and other technical objects, the process of teaming is achieved while promoting the preservation of the replicas for future generations. Modem approaches based on the wide usage of computer technologies attract a greater number of young people to explore the history of science and technology and renew their interest in the field of mechanical engineering.