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In this paper, a household intelligent vacuum robot based on STC89C52 is researched. The hardware composition and working principle of the system are introduced, and the program and flow chart are given. After continuous study and discussion, the general research, circuit research, physical welding and system debugging of the whole system are completed. In this paper, the home intelligent dust collection robot is researched to detect the obstacles along the way through e18.d80nk infrared obstacle avoidance sensor, and transmit the detected signals to the single-chip microcomputer for discrimination. The single-chip microcomputer then controls the motor steering through the L298N driving module to achieve the obstacle avoidance function, and carries out the dust collection through the bd6081 fan circuit when traveling. After the completion of the research, it can basically achieve the functions of quick response, obstacle avoidance and dust collection of household intelligent cleaner.

The Cellular Automaton (CA) modeling and simulation of solid dynamics is a long-standing difficult problem. In this paper we present a new two-dimensional CA model for solid dynamics. In this model the solid body is represented by a set of white and black particles alternatively positioned in the $x$- and $y$- directions. The force acting on each particle is represented by the linear summation of relative displacements of the nearest-neighboring particles. The key technique in this new model is the construction of eight coefficient matrices. Theoretical and numerical analyses show that the present model can be mathematically described by a conservative system. So, it works for elastic material. In the continuum limit the CA model recovers the well-known Navier equations. The coefficient matrices are related to the shear module and Poisson ratio of the material body. Compared with previous CA model for solid body, this model realizes the natural coupling of deformations in the $x$- and $y$- directions. Consequently, the wave phenomena related to the Poisson ratio effects are successfully recovered. This work advances significantly the CA modeling and simulation in the field of computational solid dynamics., Comment: 18 pages, 5 figures, Accepted for publication in Commun. Theor. Phys

A highly efficient three-dimensional (3D) Lattice Boltzmann (LB) model for high-speed compressible flows is proposed. This model is developed from the original one by Kataoka and Tsutahara [Phys. Rev. E 69 (2004) 056702]. The convection term is discretized by the Non-oscillatory, containing No free parameters and Dissipative (NND) scheme, which effectively damps oscillations at discontinuities. To be more consistent with the kinetic theory of viscosity and to further improve the numerical stability, an additional dissipation term is introduced. Model parameters are chosen in such a way that the von Neumann stability criterion is satisfied. The new model is validated by well-known benchmarks, (i) Riemann problems, including the problem with Lax shock tube and a newly designed shock tube problem with high Mach number; (ii) reaction of shock wave on droplet or bubble. Good agreements are obtained between LB results and exact ones or previously reported solutions. The model is capable of simulating flows from subsonic to supersonic and capturing jumps resulted from shock waves.

With the aim of understanding the relationships between organic small molecule field-effect transistors (FETs) and organic conjugated polymer FETs, we investigate the thickness dependence of surface morphology and charge carrier mobility in pentacene and regioregular poly (3-hexylthiophene) (RR-P3HT) field-effect transistors. On the basis of the results of surface morphologies and electrical properties, we presume that the charge carrier mobility is largely related to the morphology of the organic active layer. We observe that the change trends of the surface morphologies (average size and average roughness) of pentacene and RR-P3HT thin films are mutually opposite, as the thickness of the organic layer increases. Further, we demonstrate that the change trends of the field-effect mobilities of pentacene and RR-P3HT FETs are also opposite to each other, as the thickness of the organic layer increases within its limit.

In order to enhance the performance of regioregular poly(3-hexylthiophene) (RR-P3HT) field-effect transistors (FETs), RR-P3HT FETs are prepared by the spin-coating method followed by vacuum placement and annealing. This paper reports that the crystal structure, the molecule interconnection, the surface morphology, and the charge carrier mobility of RR-P3HT films are affected by vacuum relaxation and annealing. The results reveal that the field-effect mobility of RR-P3HT FETs can reach 4.17 × 10−2 m2/(V · s) by vacuum relaxation at room temperature due to an enhanced local self-organization. Furthermore, it reports that an appropriate annealing temperature can facilitate the crystal structure, the orientation and the interconnection of polymer molecules. These results show that the field-effect mobility of device annealed at 150 °C for 10 minutes in vacuum at atmosphere and followed by placement for 20 hours in vacuum at room temperature is enhanced dramatically to 9.00 × 10−2 cm2/(V · s).

Strong shock may induce complex processes in porous materials. We use the newly developed material-point-method to simulate such processes in an HMX-like material. To pick out relevant information, morphological characterization is used to treat with the temperature map. Via the Minkowski functional analysis the dynamics and thermodynamics of the shock wave reaction on porous HMX-like material are studied. The geometrical and topological properties of the "hot-spots" are revealed. Numerical results indicate that, shocks in porous materials are not simple jump states as classically viewed, but rather are a complex sequence of compressions and rarefactions. They cover a broad spectrum of states. We can use coarse-grained description to the wave series. A threshold value of temperature presents a Turing pattern dynamical procedure. A higher porosity is generally preferred when the energetic material needs a higher temperature for initiation. The technique of data analysis can be used to other physical quantities, for example, density, particle velocity, some specific stress, etc. From a series of studies along the line, one may get a large quantity of information for desiring the fabrication of material and choosing shock strength according to what needed is scattered or connected "hot-spots".

We present a highly efficient lattice Boltzmann model for simulating compressible flows. This model is based on the combination of an appropriate finite difference scheme, a 16-discrete-velocity model [Kataoka and Tsutahara, Phys. Rev. E 69 (2004) 035701(R)] and reasonable dispersion and dissipation terms. The dispersion term effectively reduces the oscillation at the discontinuity and enhances numerical precision. The dissipation term makes the new model more easily meet with the von Neumann stability condition. This model works for both high-speed and low-speed flows with arbitrary specific-heat-ratio. With the new model simulation results for the well-known benchmark problems get a high accuracy compared with the analytic or experimental ones. The used benchmark tests include (i) Shock tubes such as the Sod, Lax, Sjogreen, Colella explosion wave, and collision of two strong shocks, (ii) Regular and Mach shock reflections, and (iii) Shock wave reaction on cylindrical bubble problems. With a more realistic equation of state or free-energy functional, the new model has the potential tostudy the complex procedure of shock wave reaction on porous materials.

This paper investigates the effects of concentration on the crystalline structure, the morphology, and the charge carrier mobility of regioregular poly(3-hexylthiophene) (RR-P3HT) field-effect transistors (FETs). The RR-P3HT FETs with RR-P3HT as an active layer with different concentrations of RR-P3HT solution from 0.5 wt% to 2 wt% are prepared. The results indicate that the performance of RR-P3HT FETs improves drastically with the increase of RR-P3HT weight percentages in chloroform solution due to the formation of more microcrystalline lamellae and bigger nanoscale islands. It finds that the field-effect mobility of RR-P3HT FET with 2 wt% can reach 5.78 ? 10?3 cm2/Vs which is higher by a factor of 13 than that with 0.5 wt%. Further, an appropriate thermal annealing is adopted to improve the performance of RR-P3HT FETs. The field-effect mobility of RR-P3HT FETs increases drastically to 0.09 cm2/Vs by thermal annealing at 150 ?C, and the value of on/off current ratio can reach 104.

This paper investigates the morphology and crystallization properties of the two crystalline phases of pentacene grown by thermal evaporation on p+-Si substrates at room temperature by the methods of atomic force microscopy and x-ray diffraction. This kind of substrate induces a thin film phase and a triclinic phase which are formed directly onto p+-Si substrates and constitute a layer consisting of faceted grains with a step height between terraces of 15.8 A (1 A=0.1 nm) and 14.9 A, respectively. Above the critical thickness of the thin film phase, lamellar structures are found with an increasing fraction with the increase of the film thickness. When the film thickness is fixed, the fraction of lamellar structures increases with the increase of annealing temperature. These lamellar structures are identified as the second phase with a interplanar distance of 14.9 A corresponding to the pentacene triclinic phase. Furthermore, the thin film phase consisting of several micrometre sized uniformly oriented grains at an annealing temperature of less than 80°C and a deposition rate of 0.6 A/s is observed.

Lattice Boltzmann (LB) modeling of high-speed compressible flows has long been attempted by various authors. One common weakness of most of previous models is the instability problem when the Mach number of the flow is large. In this paper we present a finite-difference LB model, which works for flows with flexible ratios of specific heats and a wide range of Mach number, from 0 to 30 or higher. Besides the discrete-velocity-model by Watari [Physica A 382 (2007) 502], a modified Lax–Wendroff finite difference scheme and an artificial viscosity are introduced. The combination of the finite-difference scheme and the adding of artificial viscosity must find a balance of numerical stability versus accuracy. The proposed model is validated by recovering results of some well-known benchmark tests: shock tubes and shock reflections. The new model may be used to track shock waves and/or to study the non-equilibrium procedure in the transition between the regular and Mach reflections of shock waves, etc.

Contact algorithm between different bodies plays an important role in solving collision problems. Usually it is not easy to be treated very well. Several ones for material point method were proposed by Bardenhangen, Brackbill, and Sulsky\cite{Bardenhagen2000,Bardenhagen2001}, Hu and Chen\cite{Hu_Chen2003}. An improved one for three-dimensional material point method is presented in this paper. The improved algorithm emphasizes the energy conservation of the system and faithfully recovers opposite acting forces between contacting bodies. Contrasted to the one by Bardenhagen, both the normal and tangential contacting forces are more appropriately applied to the contacting bodies via the contacting nodes of the background mesh; Contrasted to the one by Hu and Chen, not only the tangential velocities but also the normal ones are handled separately in respective individual mesh. This treatment ensures not only the contact/sliding/separation procedure but also the friction between contacting bodies are recovered. The presented contact algorithm is validated via numerical experiments including rolling simulation, impact of elastic spheres, impact of a Taylor bar and impact of plastic spheres. The numerical results show that the multi-mesh material point method with the improved contact algorithm is more suitable for solving collision problems., Comment: Figures 1,5,6,8,10,12 in JPG format, Accepted for publication in Communications in Theoretical Physics

High performance pentacene organic thin film transistors (OTFT) were designed and fabricated using SiO2 deposited by electron beam evaporation as gate dielectric material. Pentacene thin films were prepared on glass substrate with S–D electrode pattern made from ITO by means of thermal evaporation through self-organized process. The threshold voltage VTH was −2.75±0.1V in 0 – −50V range, and that subthreshold slopes were 0.42±0.05V/dec. The field-effect mobility (μEF) of OTFT device increased with the increase of VDS, but the μEF of OTFT device increased and then decreased with increased VGS when VDS was kept constant. When VDS was −50V, on/off current ratio was 0.48 × 105 and subthreshold slope was 0.44V/dec. The μEF was 1.10cm2/(V-s), threshold voltage was −2.71V for the OTFT device.

The synchronization and asynchronization of two coupled excitable systems are investigated. The two systems with different initial configurations, which are separately a single spiral wave (or a travel wave) and the rest state, can be developed to the synchronizing state with the same spiral wave (or travel wave) in each system, when the coupling is very strong. Decreasing the coupling intensity, two rest states or two different configurations appear in the two systems. The qualitative analysis and interpretation are given.

The interaction between travelling wave impulses and spiral waves is studied and the results of their competition are related to the exciting period. From the results, it is known that the formation and development of spiral waves in cardiac tissue depend on the period by which the travelling wave impulses are excited. A method is proposed to eliminate spiral waves, which is easily operated.

The mechanism of generation and annihilation of attractors during transition from a Hamiltonian system to a dissipative system is studied numerically using the dissipative standard map. The transient process related to the formation of attracting basins of periodic attractors is studied by discussing the evolution of the KAM tori of the standard map. The result shows that as damping increases, attractors are mainly generated from elliptic orbits of the Hamiltonian system and annihilated by colliding with unstable periodic orbits originating from the corresponding hyperbolic orbits of the Hamiltonian system. The transient process also exhibits the general feature of bifurcation.

The transient properties of laser-cooled two charged particles in a Paul trap are studied numerically. We find the existence of characteristic lifetime of an attractor, which is thought to be an important feature of the transient dynamics of the weakly dissipative system. The theoretical analysis shows that it is caused by pseudo-periodic orbit which is the residual sign of periodic orbit of the focus-saddle bifurcation. Study of dissipative coupled standard maps shows that this is a general conclusion for weakly dissipative system.

In this paper, we present a variational method which is suitable for investigating the quantum Frenkel-Kontorova model. For the cases of using the coherent state and the squeezed state as the trial wave functions of the ground states, the quantum Hamiltonians and the quantum maps are given. For the second case, rye present the phase diagram and devil's stairs using the effective potential method, determine the critical points K-c for different I using Greene's criterion. The results given in the present paper are qualitatively consistent with those of the numerical experiments.([6])

Layered potassium cobaltate KxCoO2 with x = 0.36 has been successfully synthesized in KOH fluxes at 480 degrees C, and its hydrated form K0.36CoO2.yH2O (y≤0.8) has been obtained by intercalation with water. The diffraction peaks of K0.36CoO2 can be indexed by an orthorhombic cell similar to Na0.5CoO2, and K0.36CoO2.0.8H2O is isostructural with its sodium analog, monolayer hydrate NaxCoO2.yH2O. While the samples KxCoO2 and K0.36CoO2yH2O (y

The well-known superconducting oxide LiTi2O4 has a structural phase transition from spinel to ramsdellite around 900 degrees C. We have successfully obtained the superconducting spinel phase and the non-superconducting ramsdellite phase of LiTi2O4 using a hybrid microwave method. The samples are characterized by x-ray powder diffraction, scanning electron microscopy, and measurements of resistivity and magnetic susceptibility. The results show that the low-temperature spinel phase is a superconductor with Tc = 13 K, while the high-temperature ramsdellite phase is a semiconductor. By comparison between the crystal structures of the spinel and the ramsdellite phases, it is suggested that the geometrical frustration plays an important role in the superconductivity of the spinel LiTi2O4.

Two statistical properties, the nearest neighbor energy level spacing distribution P(s) and the spectral rigidity Delta(3)(L), are reported for energy level of a quantum well in a tilted magnetic field. Time-reversal (T) symmetry is broken in the system. The system is invariant under the anti-unitary combination of symmetric operations which include T, leading to what is called false T-violation. With the increasing magnetic field, P(s) and Delta(3)(L) change from Brody type-like distribution to the Gaussian orthogonal ensemble (GOE) distribution. This result is a dear manifestation of quantum chaos in the system and is in agreement with the prediction of which the false T-violation suffices to give the energy spectra the properties of the GOE, instead of the Gaussian unitary ensemble (GUE). The result indicates that the system translates from mixed-type state to quantum chaotic state. However, the spectral rigidity Delta(3) (L) turns into GUE with the magnetic field increasing. The different demonstration of P(s) and the Delta(3)(L) is due to the counting of only finite semi-classical orbits.

Relativistic momentum and energy equations of electrons in an intense laser field are derived with Hamilton-Jacobi equation. For initial electrons in non-equilibrium or Maxwellian equilibrium distributions in preplasmas, suprathermal electron energy distributions are obtained analytically and numerically. The calculation results agree well with the experiments.

The eigenvalues and eigenfunctions of the stadium-shaped quantum dot subjected to a constant magnetic field in the perpendicular direction are computed by a simple and efficient method. With the magnetic field increasing, the nearest-neighour-energy-level-spacing distribution of the stadium-shaped quantum dot is found to transform gradually from the Wigner distribution to the Poisson distribution. The transition of the nearest-neighour-energy-level-spacing distribution indicates that system changes from quantum chaotic to regular. The variation of the spatial charge distribution indicates that the system varies from bulk Landau state to the edge state that mainly affects the transport properties of the stadium-shaped quantum dot. The change of the two dimensional charge distribution near the anticrossing point is also discussed.

The aim of the present work is to generalize the method introduced by Guemez et al. [Phys. Rev. E52 (1995) R2145] Using feedback scheme, two systems can be synchronized by signals or variables which come from the driving system. Furthermore, it is possible for the systems to be synchronized by different driving signals which come from the third of fourth system. So the unmasking procedure becomes more difficult. Numerical simulations are given.

We perform a comparison study on characteristic regimes in shocked porous materials whose mechanical properties cover a wide range. Via the Minkowski functional analysis, it is found that different materials may show the same fractional size of characteristic regimes in the shock-loading procedure, even if one uses the same threshold value to define those regimes. Characteristic regimes in the material with larger initial yield are more dispersed. For a fixed shock strength, there exists a material strength with which the shock wave reaction contributes the maximum plastic work. With the decreasing of shock strength, this material strength becomes smaller. These observations may present helpful indications for new material designs.