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We report the study of a promising Ge-based magnetic heterojunction diode composed of a Mn-doped p-Ge film grown on lightly doped n-Ge film. Magnetic field dependent current rectification of the diode occurs at a low temperature. The measurements of resistivity and magnetoresistance in plane at low temperatures reveal the presence of impurity band in Ge due to Mn doping.

We study the dynamics of overdamped systems in a symmetric periodic potential against an external load. Using numerical and analytical methods, we show that a symmetric driving signal cannot rectify these systems while an asymmetric one can rectify them, causing its unidirectional rotation. We consider the case where the driving signal is multiharmonic. We find that the mean velocity of the system increases to get the highest value, by appropriate tuning of parameters.

This paper reviews the method of bosonization for one-dimensional interacting fermions. Example of its application to mesoscopic systems is presented with an explicit calculation of the spin and charge currents in an interacting quantum wire subject to a uniform magnetic field and alternating voltage source. Special emphasis is given to the details of the calculation using bosonization and Keldysh techniques.

This paper reports the fabrication of Ag/N-BuHHPDI/p-Si heterojunction diode by evaporating a layer of organic compound N-Butyl-N'-(6-hydroxyhexyl) perylene-3,4,9,10-tetracarboxylicacid-diimide (N-BuHHPDI) on top of the p-Si. The electronic properties of the heterojunction have been studied, in dark at a temperature of 300 K, by conventional current–voltage (I–V) method, Norde's method and Cheung's technique. By analyzing conventional I–V characteristics, the device exhibited rectifying behavior with a rectification ratio of 62.67 at ± 5.8 V. From the forward biased I–V measurements, the barrier height and ideality factor values of 0.83 eV and 6.4, respectively, have been obtained. Different diode parameters such as series resistance, shunt resistance, reverse saturation current and turn on voltage have been extracted from the I–V measurements. The parameters calculated from Norde's and Cheung's methods are found to be in good agreement with those calculated from conventional I–V measurements. Morphology of the N-BuHHPDI film is investigated using atomic force microscope (AFM).

We investigate the effect of changed BN nanoribbon on the rectifying behavior in zigzag graphene/BN nanoribbon heterojunction using first principles based on non-equilibrium Green’s function and density functional theory. The increased BN length in the scattering region reduces the rectifying performance of the device, and the maximum rectifying ratio is $9.8\times 10^{14}$ in the heterojunction. We discuss the different rectifying characteristics for the designed models by calculating the transmission spectra at different biases. The rectifying phenomenon is further investigated by the projected density of state of device. Furthermore, we explain the observed negative differential resistance effect by the transmission spectra and transmission eigenstates. The results suggest that the zigzag graphene/BN nanoribbon heterojunction leads to the asymmetric current, causing the rectifying phenomenon, and the BN length in the scattering region can modulate the rectifying performance of zigzag graphene/BN nanoribbon heterojunction.

Based on the proposed model for the interaction of an extremely short pulse of an electric field with chiral nanotubes (CHNTs), the case of a plane pulse passing through a thin layer of CHNTs is considered. The effect of rectification of a bipolar extremely short pulse is discovered and the dependence on the thickness of the nanotube film is investigated.

Computer support for early detection of breast cancer requires a proper mimicking of the way radiologists compare mammographic images; by comparing bilateral (images of the left and right breasts) and temporal images. In this paper, one method for bilateral registration and intensity normalization and two methods for difference analysis are described. The bilateral registration is based on anatomical features and assumptions of how the female breast is deformed under compression. The first method for differential analysis is based on the absolute difference between the registered images while the second method is based on statistical differences between properties of corresponding neighborhoods. The methods are tested on images from the MIAS database (on 100 images with 59 abnormalities distributed over four types) and evaluated by FROC-analysis. The performances of the two methods are similar but the statistical method gives better performance at a lower false positive rate and is better in particular for detecting asymmetrical developments.

Chaotic oscillations induced by single rectification in networks of linear neuron-like elements are examined on three prototype models: one nonautonomous system and two autonomous systems. The first is a system of coupled neurons with periodic input; the second is a system of three coupled neurons with six couplings; the third is a ring of four unidirectionally coupled neurons with one reverse coupling. In each system, the output function of one neuron is ramp and that of the others is linear. Each system is piecewise linear and the phase space is separated into two domains by a single border. Steady states, periodic solutions and homoclinic orbits are derived rigorously and their stability is evaluated with the eigenvalues of the Jacobian matrices. The bifurcation analysis of the three systems shows that chaotic attractors could be generated through cascades of period-doubling bifurcations of periodic solutions.

Maintenance contracts received significant attentions in the past 15 to 20 years as it has huge potential to reduce the upfront investments in maintenance infrastructure, specialized maintenance facilities, and risks to the owners through expert services provided by the original equipment manufacturers and/or specialist maintenance providers. To make maintenance contracts more effective, there is a need to develop mathematical models and understand future costs that could be built into the contract price. In this paper, a conceptual model is developed for estimating cost of outsourcing maintenance of complex and critical asset/equipment taking into account both corrective and preventive maintenance as servicing strategies and risks and penalty costs associated with such contract. The developed cost models are analyzed using illustrated numerical examples.

The effect of asymmetric lateral linking groups on the electronic transport is investigated in the biphenyl molecule-based device with gold electrodes with the framework of density functional theory and nonequilibrium Green’s function. The asymmetric lateral linking groups reduce the currents of molecular junctions, and result in the reverse rectifying behavior. The devices with asymmetric lateral linking groups –SH and –SCH₃ have maximum rectifying ratios, while the asymmetric lateral linking group –SH and –NH₂ cause minimum rectifying ratios. The calculated results suggest that the asymmetric lateral linking group induces the reduced coupling between molecule and right electrode, asymmetric distribution of frontier molecular orbital and asymmetric evolution of the molecular orbital eigenenergies, accounting for the rectifying behavior.

This paper presents a new approach for reconstructing realistic 3D models of buildings from uncalibrated image sequences taken by a hand-held camera. Firstly, correspondences between image pairs are established by using various computer vision tools, and then the fundamental matrix is estimated to high accuracy. Meanwhile, homography constraints are exploited to find more correspondences, to avoid degenerate cases and to obtain more accurate results. Secondly, rectified image pairs are resampled by using epipolar geometry constraints, where epipolar lines coincide with image scan-lines and disparities between the images are in the x-direction only. This allows subsequent stereoscopic analysis algorithms to easily take advantage of the epipolar constraint and reduce the search space to one dimension, namely along the horizontal row of the rectified images. Furthermore, dense stereo matching of the original image pairs is simple and low computational cost. Finally, the 3D model can be built through self-calibration, matching and Delaunay triangulation. The self-calibration method uses prior knowledge of orthogonal planes (lines) and parallel planes (lines) to act as constraints on the absolute quadric. A large number of experimental results show that this method improves the speed and accuracy of reconstructed 3D models and the 3D models obtained are more realistic.

We revisit the issue of directed motion induced by zero average forces in extended systems driven by ac forces. It has been shown recently that a directed energy current appears if the ac external force, f(t), breaks the symmetry f(t)=-f(t+T/2), T being the period, if topological solitons (kinks) existed in the system. In this work, a collective coordinate approach allows us to identify the mechanism through which the width oscillation drives the kink and its relation with the mathematical symmetry conditions. Furthermore, our theory predicts, and numerical simulations confirm, that the direction of motion depends on the initial phase of the driving, while the system behaves in a ratchet-like fashion if averaging over initial conditions. Finally, the presence of noise overimposed to the ac driving does not destroy the directed motion; on the contrary, it gives rise to an activation process that increases the velocity of the motion. We conjecture that this could be a signature of resonant phenomena at larger noises.

The electronic transport properties of molecular device based on photochromic diarylethene with carbon nanotube electrode are investigated by density functional theory and non-equilibrium Green’s function. The devices with open and closed configurations show a switching effect. It is found that doping of different amounts of nitrogen atoms on left electrodes results in different electronic transport properties. In addition, we discuss the observed oscillation of current in the devices induced by doping using transmission eigenstates and transmission spectra of the device. The local density of states of the device is calculated to analyze the observed rectifying behavior. The results suggest that doping of nitrogen atoms on the left electrode can be considered as a factor to modulate the electronic transport properties of molecular device.

We report here the current–voltage (i–V) characteristics of several (n⁺⁺-Si/MNOPE/C₆₀/Pt-tip) or (n⁺⁺-Si/MNOPE/SWCNT/Pt-tip) junctions, where MNOPE = 2'-mononitro-4, 4'-bis(phenylethynyl)-1-phenylenediazonium and SWCNT = single wall carbon nanotube. A layer of C₆₀ or SWCNT-derivatized MNOPE has strong effect on the i–V behavior of the junctions, including rectification, negative differential resistance (NDR) and switching behaviors. The i–V curve of a grafted molecular monolayer (GMM) of MNOPE atop n⁺⁺-Si shows NDR behavior, whereas those of C₆₀- and SWCNT-derivatized GMMs of MNOPE on n⁺⁺-Si show strong rectifying behavior with opposite rectification polarities. With C₆₀, larger currents were found with negative tip bias, while with SWCNT, the forward top bias was positive. Because C₆₀ tends to be a good electron acceptor and SWCNTs tend to be good electron donors, they show different i–V behavior, as observed. Some of the (n⁺⁺-Si/MNOPE/SWCNT/Pt-tip) junctions also show reversible bistable switching behavior.

Nanocomposites of n-type Zinc Oxide (ZnO) and p-type copper phthalocyanine (CuPc) were synthesized using solution route and the electrical properties of heterojunctions of ZnO and CuPc in the nanocomposite film was studied. For comparison, electrical properties of bilayer heterojunction devices using ZnO nanostructure drop cast film and thermally evaporated CuPc were also studied. Rectification ratio (RR) of about 28 and 5.5 was obtained at 4 V for devices with nanocomposite film and bilayer heterojunctions indicating improved formation of p–n junction characteristics for nanocomposite films. Values of ideality factor, barrier height at the p–n junction interface and series resistance were estimated using different methods like semilog plots, Cheung and Norde's methods. Ideality factor estimated from semilog plots and Cheung's methods were found to be higher than unity indicating deviation from ideal diode behavior. Barrier height estimated from different methods was about 0.7 eV. Series resistance measured using Cheung and Norde's methods were found to be about 92 KΩ and 21 KΩ, respectively. Bilayer heterojunction devices exhibited much higher series resistance, ideality factor and barrier height as estimated using all the above-mentioned methods as compared to the devices with nanocomposite film. The above results indicate intimate mixing and improved interface between ZnO and CuPc in the in situ synthesized nanocomposite film thereby offering improved p–n junction characteristics.

The diffusive transport of electrons in the F/I/N/I/F system placed in an external magnetic field is investigated. It is shown that the rectification effect appears when the magnetic structure (i.e., the direction of magnetization in the ferromagnetic layers and the direction of the external magnetic field) is noncoplanar. The dependence of the diode effect on the thickness of the middle normal metal layer is calculated. The effect cubically increases when the thickness is small and decays exponentially when the thickness is large.

We studied the thermal rectification effect in one-dimensional chains using the non-equilibrium Green's function method. Thermal rectification effect is observed in the presence of structure asymmetry and nonlinear interactions. We found that phonons with higher frequencies play a major role in thermal rectification. By controlling the phonon frequency band in the junction region, we are able to obtain rectification rate up to four percent. The results are comparable to experiment, and provide a clear interpretation of the physical processes involved.

Through to the state-level key cultural relic Kaifeng iron tower’s damage origin analysis, according to its brick masonry structure stress characteristic, the iron tower incline key aspect “the water” “the earth” the nature, the tower body and the tower footing foundation coordinated work and so on, proposed that the Kaifeng iron tower incline corrects an error the technical processing plan, provides the essential reference for the brick structure tower’s protection.

This paper reviews the method of bosonization for one-dimensional interacting fermions. Example of its application to mesoscopic systems is presented with an explicit calculation of the spin and charge currents in an interacting quantum wire subject to a uniform magnetic field and alternating voltage source. Special emphasis is given to the details of the calculation using bosonization and Keldysh techniques.