Band 62, Heft 10-11

In this paper, dependent and independent variable transformations are introduced to solve the sinh- Gordon equation by using the knowledge of the elliptic equation and Jacobian elliptic functions. It is shown that different kinds of solutions can be obtained to the sinh-Gordon equation, including breather lattice solutions and periodic wave solutions.

The Planck -Kleinert Crystal hypothesis is analyzed for an ideal cubic fcc crystal formed by Planck particles. In this type of a quasi-continuum the energy, momentum, and mass transport are described by the classical balance equations. The transverse wave is the electromagnetic wave, and its velocity equals the velocity of light. The quasi-stationary collective movement of mass in the crystal is equivalent to the particle (body), and such an approach enables derivation of the Schrödinger equation. The diffusing interstitial Planck particles create a gravity field, and the computed value of G is within the accuracy of experimental data. The model predicts four different force fields and a vast amount of the “dark matter and dark energy” in the crystal lattice. It allows for a self-consistent interpretation of multiscale phenomena.

The existence of conservation laws (invariants) are discussed for various one-dimensional cellular automata. The cellular automata are derived from partial differential equations. Both irreversible and reversible cellular automata are investigated.

We consider a nonlinear oscillator simultaneously excited by external and parametric functions. The oscillator has a bias parameter that breaks the symmetry of the motion. The example that we use to illustrate the problem is the rolling oscillation of a biased ship in longitudinal waves, but many mechanical systems display similar features. The analysis took into consideration linear, quadratic, cubic, quintic, and seven terms in the polynomial expansion of the relative roll angle. The damping moment consists of the linear term associated with radiation and viscous damping and a cubic term due to frictional resistance and eddies behind bilge keels and hard bilge corners. Two methods (the averaging and the multiple time scales) are used to investigate the first-order approximate analytical solution. The modulation equations of the amplitudes and phases are obtained. These equations are used to obtain the stationary state. The stability of the proposed solution is determined applying Liapunov’s first method. Effects of different parameters on the system behaviour are investigated numerically. Results are presented graphically and discussed. The results obtained by two methods are in excellent agreement.

We analyze a time series of the combustion pressure in the idle state, measured from a spark ignition engine of a motorcycle. It is clarified that the engine system can be described by a lowdimensional deterministic dynamics perturbed by some stochastic process.We also propose a method to stabilize the chaotic behaviour of engine’s data by adopting the Pyragas’ method. We actually use this method in a computer experiment for the control of combustion pressure data to demonstrate the efficiency of the proposed method. As a result of the experiment, we eliminate the fluctuations in the combustion pressure data and obtain a periodic orbit.

We present adhesion and surface energies of Fe-Mg binary alloys from simulation studies. The adhesion energy was calculated using the assumption that work is done when atoms come into contact by moving two surfaces from equilibrium position z o to ∞, while the surface traction was determined from the atomic interactions between atoms. The surface tension variation with temperature was investigated from the diffusion coefficient obtained by performing molecular dynamics simulations at temperatures above the eutetic temperature of Fe-Mg. It was observed that the structural information as well as the calculated surface tension suggest segregation in Fe-Mg alloys at all investigated temperatures.

It is proposed to simultaneously compress a thermonuclear target and amplify a laser beam by a single z-pinch discharge. The laser beam is imploded and amplified by a cylindrical convergent shock wave inside a capillary, transforming it into a soft X-ray pulse for the fast ignition of the thermonuclear target. The target is compressed inside a liner by the z-pinch current. The capillary is attached to one end of the cylindrical target, and is protected by a radial wire spoke array fast opening switch against its premature implosion by the convergent shock wave. The z-pinch can be stabilized by placing it into a powerful vortex.

A relationship between the mobility and diffusivity of semiconductors exhibiting bandgap narrowing has been presented. The relationship is general and applicable to both non-degenerate and degenerate semiconductors under an applied bias. It is suitable for the investigation of the electrical transport in heavily doped semiconductors.

The effects of thermal annealing on the bulk transport properties of poly(3-hexylthiophene) (P3HT) were studied by analyzing room temperature current-voltage characteristics of polymer thin films sandwiched between indium tin oxide/poly[ethylene dioxythiophene]:poly[styrene sulfonate] (ITO/PEDOT:PSS) and aluminum electrodes, before and after a thermal annealing step. It was observed that annealing takes place in two steps: (1) Dedoping of the polymer of impurities such as oxygen, remnant solvent, water, leading to a decrease in the conductivity of the film, and (2) thermally induced motion of the polymer chains leading to closer packing, thus, stronger inter-chain interaction and, consequently, increase in conductivity. It was also observed that the ITO/PEDOT:PSS/P3HT hole injection barrier increases on annealing the ITO/PEDOT:PSS/P3HT/Al thin film devices. The implications of impurity dedoping and closer packing on the output characteristics of bulk heterojunction polymer-fullerene thin film solar cells are discussed.

The process of amplification of a single spin state using nuclear magnetic resonance (NMR) techniques in a rotating frame is considered. Our main aim is to investigate the efficiency of various schemes for quantum detection. Results of numerical simulation of the time dependence of individual and total nuclear polarizations for 1D, 2D, and 3D configurations of the spin systems are presented.

93 Nb nuclear spin-spin relaxation has been examined in the low-dimensional antiferromagnet Fe 0.25 NbS 2 between 4.2 K and 300 K. The relaxation is characterized by two T 2 ’s. The temperature dependence is discussed together with the origin of the disappearance of the fast decay at low temperatures.

Using 1 H NMR T 1 and T 1ρ measurements self-diffusion of NH 4 + with an activation energy of (80 ± 10) kJ mol −1 was detected in the highest-temperature phase of NH 4 NO 2 crystals. Narrow 15 N NMR spectra of 15 NH 4 NO 2 and NH 4 15 NO 2 revealed that the isotropic reorientation rates of NH 4 + and NO 2 − ions are rapid in the high-temperature solid phase. These results suggest that the high-temperature phase of NH 4 NO 2 crystals forms an ionic plastic phase.

In the present work some transport properties of the binary room temperature molten salt (RTMS) lithium bis(trifluoromethane sulfone)imide (LiTFSI)-acetamide [LiN(SO 2 CF 3 )2-CH 3 CONH 2 ], applied in an Li-ion battery, have been investigated. The phase diagram was determined by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The result reveals that the binary RTMS has an eutectic point at 201 K and the 30 mol% LiTFSI composition. The electric conductivity was measured using a direct current computerized method. The result shows that the conductivities of the melts increase with increasing temperature and acetamide content. The densities of all melts decrease with increasing temperature and acetamide content. The equivalent conductivities were fitted by the Arrhenius equation, where the activation energies were 18.15, 18.52, 20.35, 25.08 kJ/mol for 10, 20, 30, 40 mol% LiTFSI, respectively. Besides the relationships between conductivity, density composition and temperature, of the ion interaction is discussed.

The electroreduction of CO 3 2− ions on a molybdenum cathode in a NaCl-KCl-Li 2 CO 3 melt was studied by cyclic voltammetry. The electrochemical synthesis of Mo 2 C on molybdenum substrates has been performed at 1123 K for 7 h with a cathodic current density of 5 mA cm −2 . If molybdenum carbide is present as a thin (ca. 500 nm) film on a molybdenum substrate (Mo 2 C/Mo), its catalytic activity in the water gas-shift reaction is enhanced by at least an order of magnitude compared to that of the bulk Mo 2 C phase.

Electrochemical polarization and reduction experiments are reported which were performed with a three-terminal cell and a molten salt electrolyte consisting of calcium chloride with additions of calcium oxide. Employing a metal cathode, a graphite anode and a pseudo-reference electrode also made from graphite, polarization measurements were carried out with the aim to validate the performance of the pseudo-reference electrode and to assess the stability of the electrolyte. Using a chromium sesquioxide cathode in conjunction with a graphite anode and a graphite pseudo-reference electrode, electrochemical reduction experiments were conducted under potentiostatic control. The key results are: a graphite pseudo-reference electrode has been shown to be appropriate in the present type of molten salt electrochemical experiments that take place on a time scale of many hours; the conversion of chromium oxide into chromium metal has been accomplished under cathodic potential control and in the absence of calcium metal deposition; a significant amount of calcium oxide in the calcium chloride has been found necessary to preclude anodic chlorine formation throughout the entire experiment; a considerable overpotential has been identified at the anode.

The reaction of uranium dioxide with excess hydrogen chloride in alkali chloride melts (LiCl, 3LiCl-2KCl, NaCl-KCl and NaCl-2CsCl) has been studied between 450 and 750 ◦ C, and the reaction products were characterized by electronic absorption and X-ray absorption spectroscopy. Uranium( V), [UO 2 Cl 4 ] 3− , and uranium(IV), [UCl 6 ] 2− , species were formed. They depended upon the temperature and the radius of the alkali cations present. Uranium(V) ions predominated in melts with small cations (LiCl and 3LiCl-2KCl).