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Journal Cover Modern Physics Letters B
  [SJR: 0.222]   [H-I: 33]   [9 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0217-9849 - ISSN (Online) 1793-6640
   Published by World Scientific Homepage  [118 journals]
  • AND and OR logic gates based on a phononic crystal ring resonator cavity
    • Authors: Zhenlong Xu, Fugen Wu, Zhongning Guo
      Abstract: Modern Physics Letters B, Volume 30, Issue 31, 20 November 2016.
      We propose AND and OR logic gates based on a phononic crystal (PNC) ring resonator cavity. The proposed devices consist of ring resonator cavities coupled to PNC line defect waveguides. The logic gate performance has been analyzed and investigated using finite element methods. The design specifies a logical 0 as a transmission rate of 0.3 or less and a logical 1 as a transmission rate of 0.6 or more. The results show that such a design has stable transmission peaks, meeting the requirements of acoustic logic gates. The design has the potential to be a key component in future phononic integrated circuits.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-21T06:19:42Z
      DOI: 10.1142/S0217984916503887
       
  • Morphological, thermal and optical studies of jute-reinforced
           PbSrCaCuO–polypropylene composite
    • Authors: Reenu Jacob, Jayakumari Isac
      Abstract: Modern Physics Letters B, Volume 30, Issue 31, 20 November 2016.
      New research with modern technologies has always grabbed substantial attention. Conservation of raw materials like natural fibers has helped composite world to explore eco-friendly components. The aim of this paper is to study the potential of jute fiber-reinforced ceramic polymers. Alkali-treated jute fiber has been incorporated in a polypropylene ceramic matrix at different volume fractions. The morphological, thermal and optical studies of jute-reinforced ceramic Pb2Sr2CaCu2O9 (PbSrCaCuO) are studied. Morphological results evidently demonstrate that when the polypropylene ceramic matrix is reinforced with jute fiber, interfacial interaction between the varying proportions of the jute fiber and ceramic composite takes place. TGA and DSC results confirm the enhancement in the thermal stability of ceramic composites reinforced with jute fiber. The UV analysis of the composite gives a good quality measure on the optical properties of the new composite prepared.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-21T06:19:31Z
      DOI: 10.1142/S0217984916503796
       
  • Thermodynamic properties of rod-like chains: Entropic sampling simulations
    • Authors: L. S. Ferreira, L. N. Jorge, A. A. Caparica, D. A. Nascimento, Minos A. Neto, J. R. Sousa
      Abstract: Modern Physics Letters B, Volume 30, Issue 31, 20 November 2016.
      In this work, we apply entropic sampling simulations to a three-state model which has exact solutions in the microcanonical and grand-canonical ensembles. We consider N chains placed on an unidimensional lattice, such that each site may assume one of the three states: empty (state 1), with a single molecule energetically null (state 2), and with a single molecule with energy [math] (state 3). Each molecule, which we will treat here as dimers, consists of two monomers connected one to each other by a rod. The thermodynamic properties such as internal energy, densities of dimers and specific heat were obtained as functions of temperature, where the analytic results in the microcanonical and grand-canonical ensembles were successfully confirmed by the entropic sampling simulations.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-21T06:19:06Z
      DOI: 10.1142/S0217984916503784
       
  • Effect of magnetic structural processing on structure and texture of
           La2Zr2O7 buffer layers
    • Authors: F. Kh. Chibirova, G. V. Kotina, E. A. Bovina, D. V. Tarasova, A. A. Polisan, Yu. N. Parkhomenko
      Abstract: Modern Physics Letters B, Ahead of Print.
      Epitaxial CeO2 seed layer and La2Zr2O7 (LZO) buffer layers were deposited on biaxially-textured Ni–5 at.% W (NiW) tape substrate by liquid-phase polymer assisted nanoparticles deposition (PAND) method. LZO layers deposited by PAND have consistently shown tilting of the [math]-axis toward the direction of the sample’s surface normal. A new approach increasing the sharpening of the buffer texture by magnetic structural processing (MSP) of buffer layers was tested. The LZO layers, deposited on the seed and buffer layers after MSP, have dense and smooth surface structure, and more importantly, significantly improved out-of-plane texture, compared with the LZO layers that were deposited on a layer without MSP. Transmission electron microscopy study confirmed the [math]-axis tilting of CeO2 and LZO layers and revealed the absence of interfaces between LZO layers which have been grown on the layers after MSP. There are very small (2–4 nm) gated pores in the single-crystal structure of LZO layers that are not typical for structure of LZO layers obtained by liquid-phase methods. Thus the LZO buffer layers can serve as an effective metal-ion diffusion barrier.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-28T02:30:33Z
      DOI: 10.1142/S0217984916503905
       
  • Perfect spin-filter devices based on zigzag zinc oxide nanoribbons
    • Authors: Zi-Yue Zhang
      Abstract: Modern Physics Letters B, Ahead of Print.
      Spin-polarized electron transport through a zigzag zinc oxide nanoribbon (ZnONR) has been studied using first-principles transport simulations. Ribbons without edges passivated show 100% spin polarization at small bias voltage independently of width. The ribbons with edge zinc atoms passivated maintain absolute spin-filtering effect in much larger bias region. The results demonstrate that zigzag ZnONRs act as perfect spin-filters in the absence of magnetic electrodes and external fields.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-28T02:30:32Z
      DOI: 10.1142/S0217984916503929
       
  • Investigations on Cu[math]-substituted Ni–Zn ferrite nanoparticles
    • Authors: Amarjeet, Vinod Kumar
      Abstract: Modern Physics Letters B, Ahead of Print.
      [math] ([math] = 0.1, 0.3 and 0.5) nanoparticles were prepared by chemical co-precipitation method. The developed nanoparticles were characterized for structural properties by powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. Peak position in the X-ray diffraction pattern confirmed the single spinel phase of the developed particles. Infrared (IR) spectroscopy in mid-IR range showed the presence of characteristic absorption bands corresponding to octahedral and tetrahedral bonds in the spinel structure of prepared samples. Thermo-gravimetric analysis (TGA) measurements showed a considerable weight loss in the developed samples above 700[math]C. Frequency dependence of the electrical properties of the developed material pellets was studied in the frequency range of 1 kHz–5 MHz. Temperature dependence of the dielectric constant of [math] was studied at different temperatures, i.e. at 425, 450 and 475 K, in the frequency range of 1 kHz–5 MHz. It was found that the electrical conductivity decreases with increasing Cu[math] ion content while it increases with the increase in temperature.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-28T02:30:31Z
      DOI: 10.1142/S0217984916503474
       
  • A comparison of Pd and Au electrodes-based LiNbO3
           surface acoustic wave devices
    • Authors: Bo Liu, Mohammad Ali Mohammad, Dan-Yang Wang, Xiang-Guang Tian, Lu-Qi Tao, Yi Yang, Tian-Ling Ren
      Abstract: Modern Physics Letters B, Ahead of Print.
      We report the comparison of electrode metals for LiNbO3 surface acoustic wave (SAW) devices. Palladium (Pd) was systematically studied as a SAW electrode metal for the first time, compared with gold (Au). Simulations were first conducted to gain an understanding of the differences of the materials and the metallization ratio. Two sets of identical SAW devices were then fabricated using Au and Pd as electrodes with different electrode widths and same SAW period. The insertion losses, types of resonance mode, the resonance frequencies, peak amplitudes, quality factors and trends with different metallization ratios were systematically compared and analyzed. We found that Pd electrode devices only exhibit the parallel resonance frequency and have higher resonance frequency for both the first-order and third-order harmonics. Au electrode devices tend to have a smooth response and a quality factor two times higher than Pd. Both Pd and Au electrode devices have nearly identical electromechanical coupling coefficients, and the quality factor and third-order harmonics both improve with increasing metallization ratio.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-28T02:30:30Z
      DOI: 10.1142/S0217984916503498
       
  • Structural, electronic, sodium diffusion and elastic properties of Na–P
           alloy anode for Na-ion batteries: Insight from first-principles
           calculations
    • Authors: Huansheng Lu, Bo Xu, Jing Shi, Musheng Wu, Yinquan Hu, Chuying Ouyang
      Abstract: Modern Physics Letters B, Ahead of Print.
      Sodium-ion batteries (NIBs) as an alternative to lithium-ion batteries (LIBs) have recently received great attentions because of the relatively high abundance of sodium. Searching for suitable anode materials has always been a hot topic in the field of NIB study. Recent reports show that phosphorus-based materials are potential as the anode materials for NIBs. Using first-principles calculations, herein, we study the atomic and electronic structures, diffusion dynamics and intrinsic elastic properties of various Na–P alloy compounds (NaP5, Na3P[math], NaP and Na3P) as the intermediate phases during Na extraction/insertion in phosphorus-based anode materials. It is found that all the crystalline phases of Na–P alloy phases considered in our study are semiconductors with band gaps larger than that of black phosphorus (BP). The calculations of Na diffusion dynamics indicate a relatively fast Na diffusion in these materials, which is important for good rate performance. In addition, the diffusion channels of sodium ions are one-dimensional in NaP5 phase and three-dimensional in other three phases (Na3P[math], NaP and Na3P). Elastic constant calculations indicate that all four phases are mechanically stable. Among them, however, NaP5, Na3P[math] and NaP alloy phases are ductile, while the fully sodiated phase Na3P is brittle. In order to improve the electrochemical performance of Na–P alloy anodes for NIBs, thus, promoting ductility of Na–P phase with high sodium concentration may be an effective way.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-28T02:30:29Z
      DOI: 10.1142/S0217984916503851
       
  • Thermal quantum speed limit for classical-driving open systems
    • Authors: W.-J. Wu, K. Yan, Yinzhong Wu, Xiang Hao
      Abstract: Modern Physics Letters B, Ahead of Print.
      Quantum speed limit (QSL) time for open systems driven by classical fields is studied in the presence of thermal bosonic environments. The decoherence process is quantitatively described by the time convolutionless master equation. The evolution speed of an open system can be accelerated by means of driving classical fields at finite temperatures. It is found out that the structural reservoir at low temperature may contribute to the acceleration of quantum evolution. The manifest oscillation of QSL time happens under the circumstance of classical driving field. The scaling property of QSL for entangled systems is also investigated. It is demonstrated that the entanglement of open systems can be considered as one kind of resource for improving the potential capacity of thermal quantum speedup.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-28T02:30:27Z
      DOI: 10.1142/S0217984916503899
       
  • Effects of ionized impurity and interface roughness scatterings on the
           electron mobility in InAs/GaSb type II superlattices at low temperatures
    • Authors: S. Safa, A. Asgari
      Abstract: Modern Physics Letters B, Ahead of Print.
      The in-plane electron mobility has been calculated in InAs/GaSb type-II superlattices (SLs) at low temperatures. The interface roughness scattering and ionized impurity scattering are investigated as the dominant scattering mechanisms in limiting the electron transport at low temperatures. For this purpose, the band structures and wave functions of electrons in such SLs are calculated by solving the K.P Hamiltonian using the numerical Finite Difference method. The scattering rates have been obtained for different temperatures and structural parameters. We show that the scattering rates are high in thin-layer SLs and the mobility rises as the temperature increases in low-temperature regime.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-28T02:30:26Z
      DOI: 10.1142/S021798491650384X
       
  • Solitons, Bäcklund transformation and Lax pair for a generalized
           variable-coefficient Boussinesq system in the two-layered fluid flow
    • Authors: Xue-Hui Zhao, Bo Tian, Jun Chai, Yu-Xiao Wu, Yong-Jiang Guo
      Abstract: Modern Physics Letters B, Ahead of Print.
      Under investigation in this paper is a generalized variable-coefficient Boussinesq system, which describes the propagation of the shallow water waves in the two-layered fluid flow. Bilinear forms, Bäcklund transformation and Lax pair are derived by virtue of the Bell polynomials. Hirota method is applied to construct the one- and two-soliton solutions. Propagation and interaction of the solitons are illustrated graphically: kink- and bell-shape solitons are obtained; shapes of the solitons are affected by the variable coefficients [math], [math] and [math] during the propagation, kink- and anti-bell-shape solitons are obtained when [math], anti-kink- and bell-shape solitons are obtained when [math]; Head-on interaction between the two bidirectional solitons, overtaking interaction between the two unidirectional solitons are presented; interactions between the two solitons are elastic.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-28T02:30:25Z
      DOI: 10.1142/S0217984916503838
       
  • Research on PGNAA adaptive analysis method with BP neural network
    • Authors: Ke-Xin Peng, Jian-Bo Yang, Xian-Guo Tuo, Hua Du, Rui-Xue Zhang
      Abstract: Modern Physics Letters B, Ahead of Print.
      A new approach method to dealing with the puzzle of spectral analysis in prompt gamma neutron activation analysis (PGNAA) is developed and demonstrated. It consists of utilizing BP neural network to PGNAA energy spectrum analysis which is based on Monte Carlo (MC) simulation, the main tasks which we will accomplish as follows: (1) Completing the MC simulation of PGNAA spectrum library, we respectively set mass fractions of element Si, Ca, Fe from 0.00 to 0.45 with a step of 0.05 and each sample is simulated using MCNP. (2) Establishing the BP model of adaptive quantitative analysis of PGNAA energy spectrum, we calculate peak areas of eight characteristic gamma rays that respectively correspond to eight elements in each individual of 1000 samples and that of the standard sample. (3) Verifying the viability of quantitative analysis of the adaptive algorithm where 68 samples were used successively. Results show that the precision when using neural network to calculate the content of each element is significantly higher than the MCLLS.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-28T02:30:23Z
      DOI: 10.1142/S0217984916503863
       
  • Study on the influence of driving distraction on traffic flow considering
           the stochastic duration time of distraction
    • Authors: Yao Xiao, Jing Shi
      Abstract: Modern Physics Letters B, Ahead of Print.
      This paper aims to study the traffic flow characteristics considering drivers’ distraction behavior, which is common and lasts for stochastic duration time. The distribution of distraction duration time and the influence of distraction on traffic flow are analyzed. The relationship among distraction duration time, probability of distraction occurrence and proportion of distraction is established by stochastic model. Then a modified optimal velocity model was proposed to simulate a two-lane road, taking the effect of distraction behavior into account. A survey was conducted to collect maximum speed, average speed, lane change frequency and headway of vehicle when distracted. The results suggest that distraction behavior has significant negative influence on traffic flow rate and increases the lane changing frequency. Short-time distraction seems to have smaller impact on traffic flow than long-time distraction. This model simulates the distraction behavior very well and distracted drivers have lower mean speed, lower lane changing frequency, longer headway and are overtaken by more vehicles in simulation. This study provided a good model to analyze distraction behavior in traffic flow and pointed out an important factor affecting the traffic flow efficiency.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-24T10:37:47Z
      DOI: 10.1142/S0217984916503802
       
  • Investigation of high thickness holographic gratings in acrylamide-based
           photopolymer
    • Authors: Heng Wang, Shifeng Xu, Jia Ma, Zhaoyang Wang, Enzhu Hou
      Abstract: Modern Physics Letters B, Ahead of Print.
      We studied the holographic characteristics of acrylamide-based photopolymer layers ranging in thickness from 300 [math] to 1000 [math]. Scattering patterns of various materials were presented, and both transmittance and scattering ratio were measured. Then, theoretical and experimental Bragg selectivity curves of two samples with thicknesses of 300 [math] and 510 [math] were analyzed, demonstrating the effective optical thickness inside photopolymer, which was responsible for the width of Bragg selectivity curve. Through the simulation for the spatial dynamics of refractive index distribution inside materials with different thicknesses, the attenuation of grating along the direction of thickness inside photopolymer was presented. Moreover, the photo-induced polymer chain length was evaluated, and a growing tendency of polymer chain length as increasing depth of material thickness was presented for the first time, in other words, there were polymers with longer chain length in deeper layer of material.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-24T10:37:47Z
      DOI: 10.1142/S0217984916503826
       
  • Link community detection by non-negative matrix
           factorization with multi-step similarities
    • Authors: Xianchao Tang, Guoqing Yang, Tao Xu, Xia Feng, Xiao Wang, Qiannan Li, Yanbei Liu
      Abstract: Modern Physics Letters B, Ahead of Print.
      Uncovering community structures is a fundamental and important problem in analyzing the complex networks. While most of the methods focus on identifying node communities, recent works show the intuitions and advantages of detecting link communities in networks. In this paper, we propose a non-negative matrix factorization (NMF) based method to detect the link community structures. Traditional NMF-based methods mainly consider the adjacency matrix as the representation of network topology, while the adjacency matrix only shows the relationship between immediate neighbor nodes, which does not take the relationship between non-neighbor nodes into consideration. This may greatly reduce the information contained in the network topology, and thus leads to unsatisfactory results. Here, we address this by introducing multi-step similarities using the graph random walk approach so that the similarities between non-neighbor nodes can be captured. Meanwhile, in order to reduce impact caused by self-similarities (similarities between nodes themselves) and increase importance gained from similarities between other different nodes, we add a penalty term to our objective function. Then an efficient optimization scheme for the objective function is derived. Finally, we test the proposed method on both synthetic and real networks. Experimental results demonstrate the effectiveness of the proposed approach.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-24T10:37:46Z
      DOI: 10.1142/S021798491650370X
       
  • Conservation laws of a perturbed Kaup–Newell equation
    • Authors: Jing-Yun Yang, Wen-Xiu Ma
      Abstract: Modern Physics Letters B, Ahead of Print.
      A new Lax pair is introduced for a perturbed Kaup–Newell equation and used to construct two series of conservation laws through a Riccati equation that a ratio of eigenfunctions satisfies. Both series of conservation laws are defined recursively, and the first two in each series are presented explicitly.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-24T10:37:45Z
      DOI: 10.1142/S0217984916503814
       
  • Analytic solutions and their dynamics of atomic–molecular
           
    • Authors: Huilan Wu, Yuqin Yao
      Abstract: Modern Physics Letters B, Ahead of Print.
      The time- and space-modulated nonlinearity is the important character of the Bose–Einstein condensates (BECs). Many works have been done on atomic BECs with spatially modulated nonlinearity, but there is little work on atomic–molecular BECs. In this paper, we construct one family of explicitly exact solutions of the atomic–molecular BECs with time- and space-modulated nonlinearities and trapping potential by similarity transformations. We discuss the dynamics of matter waves including breathing solitons, quasi-breathing solitons, resonant solitons and moving solitons. We analyze the linear stability of the solutions by adding various initial stochastic noise. We also provide the experimental parameters to produce these phenomena in future experiments.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-23T09:27:50Z
      DOI: 10.1142/S0217984916503723
       
  • The origin of ferromagnetism of Co-doped TiO2 nanoparticles: Experiments
           and theory investigation
    • Authors: Suyin Zhang, Zhongpo Zhou, Rui Xiong, Jing Shi, Zhihong Lu, Haiying Wang
      Abstract: Modern Physics Letters B, Ahead of Print.
      A series of Ti[math]Co[math]O[math] ([math] = 0.01, 0.03, 0.05, 0.07) nanoparticles were synthesized by sol–gel method. The X-ray diffraction, transmission electron microscopy, Raman analysis and X-ray photoelectron spectroscopy ruled out the signatures of Ti[math], Co-clusters or any other oxides of Co. The ferromagnetic behavior was clearly observed at room temperature in doped samples with saturation magnetization [math] of the order of 0.008–0.035 emu/g depending on doping concentrations. The saturation magnetization is found to be increased with the Co contents increasing from 1% to 7%. From the plot of the M–T curve, we obtain the [math] as [math][math]515 K for 5% Co-doped TiO2. Oxygen vacancies were detected from the photoluminescence (PL) measurement. Magnetic properties analyses and PL analyses showed that oxygen vacancies probably played a major role in ferromagnetism of the Ti[math]Co[math]O2 system with Co substituting for Ti. The first-principles calculation was performed to investigate the magnetic properties of Co-doped TiO2 nanoparticles. It can be found that the major magnetic moment is from the 3d electron of Co. The experiment results are consistent with the first-principles calculation. The ferromagnetism derived from the spin-split of O-2p and Co-3d electron states caused by p–d orbit hybridization.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-23T09:27:49Z
      DOI: 10.1142/S0217984916502961
       
  • Two kinds of finite-dimensional integrable reduction
           to the Harry–Dym hierarchy
    • Authors: Jinbing Chen
      Abstract: Modern Physics Letters B, Ahead of Print.
      In this paper, two kinds of finite-dimensional integrable reduction are studied for the Harry–Dym (HD) hierarchy. From the nonlinearization of Lax pair, the HD hierarchy is reduced to a class of finite-dimensional Hamiltonian systems (FDHSs) in view of a Bargmann map and a set of Neumann type systems by a Neumann map, which separate temporal and spatial variables on the symplectic space [math] and the tangent bundle of ellipsoid [math], respectively. It turns out that involutive solutions of the resulted finite-dimensional integrable systems (FDISs) directly give rise to finite parametric solutions of HD hierarchy through the Bargmann and Neumann maps. The finite-gap potential to the high-order stationary HD equation is obtained that cuts out a finite-dimensional invariant subspace for the HD flows. Finally, some comparisons of two kinds of integrable reductions are then discussed.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-16T11:36:09Z
      DOI: 10.1142/S0217984916503966
       
  • Stochastic resonance in tristable system induced by dichotomous noise
    • Authors: Peiming Shi, Xiao Su, Dongying Han
      Abstract: Modern Physics Letters B, Ahead of Print.
      Stochastic resonance (SR) of a tristable system driven by dichotomous noise (DN) is investigated firstly by the mean signal-to-noise ratio gain (SNR-GM). Utilizing an efficiently numerical algorithm, we acquire the asymmetric DN accurately. Then the system responses and the SNR-GM as the signatures of the stochastic resonance are calculated by the fourth-order Runge–Kutta algorithm. It is founded that the change of system parameters [math] and [math] in a certain range can induce SR phenomenon. Moreover, with the increase of parameter [math], the amplitude of SNR-GM increases and shows the trend of moving to the left. For the different state values of the symmetric DN, the SNR-GM will increase with the increase of state value [math] and [math] but only a highest peak and the interval of SR shift to the left. However, with the increase of forcing frequency, the SNR-GM decreases and the interval of SR moves to right. In addition to, the highest peak of SNR-GM will decrease with the increase of periodic signal amplitude. These results provide a reliable basis for how to realize the parameter selection of stochastic resonance in tristable system driven by DN.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-15T06:13:40Z
      DOI: 10.1142/S0217984916503772
       
  • New model of the pinning potential barrier in layered HTc superconductors
    • Authors: J. Sosnowski
      Abstract: Modern Physics Letters B, Ahead of Print.
      New model of the pinning potential barrier in multilayered HTc superconductors is presented, based on geometrical approach to the capturing interaction of pancake-type vortices with nano-sized defects. Using the above model the transport current flow phenomena in these materials, especially the current–voltage characteristics and critical current density, have been considered. Details of theoretical analysis are given, including the derivation of basic mathematical equations describing the potential barrier as a function of transport current intensity and the initial position of captured pancake vortex. Computer simulation has been performed of the influence of transport current amplitude on the potential barrier height for various sizes of pinning centers and initial pancake vortex position as well as the influence of fast neutrons irradiation creating nano-sized defects on critical current of HTc layered superconductor.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-15T06:13:38Z
      DOI: 10.1142/S0217984916503875
       
  • Theoretical analysis on the sensitivity to partial pressure of oxygen of
           the band gap shift in CdO thin films
    • Authors: M. A. Grado-Caffaro, M. Grado-Caffaro
      Abstract: Modern Physics Letters B, Ahead of Print.
      With the aim of providing an analytical approach (not accurate numerical results), for the first time, the sensitivity to the partial pressure of oxygen of the shift in the energy band gap experienced by cadmium-oxide thin films is evaluated for the visible region by introducing a suitable parameter. The sensitivity to the above pressure of the spatial carrier density is determined and compared with the sensitivity relative to the band gap shift. The gradient of the CdO carrier concentration as a function of the partial pressure of oxygen appears in the expressions for the two above sensitivity functions but the goal of this paper is not computing numerically this gradient so only qualitative estimations are done. In relation to the above results, the kinetics relative to the formation of CdO thin films are investigated. In addition, the sensitivity to the pressure in question of the corresponding optical-absorption shift in the visible range is calculated.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-15T06:13:36Z
      DOI: 10.1142/S0217984916503711
       
  • Tunable power splitter based on MIM waveguide-rectangle cavity system with
           Kerr material
    • Authors: Fang Chen, Yiping Xu
      Abstract: Modern Physics Letters B, Ahead of Print.
      A tunable power splitter based on metal-dielectric metal (MDM) waveguide coupled with rectangle cavity with Kerr nonlinear material is proposed. The power splitter properties are simulated by the finite-difference time-domain (FDTD) method [Y. H. Guo et al., Opt. Express 19 (2011) 13831–13838]. Simple theoretically analysis and numerically calculation demonstrate that the waveguide-rectangle cavity coupled system performs a tunable plasmonic power splitter. Additionally, the output power ratio can be efficiency tuned by varying the control light intensity. Results obtained by the coupled mode theory are consistent with those from the FDTD simulation. The plasmonic splitter may become a choice for the highly integrated optical circuits.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-15T06:13:34Z
      DOI: 10.1142/S0217984916503760
       
  • Microstructural features and mechanical properties of 18 MeV
           He[math] ions irradiated pure Zr
    • Authors: Mohsin Rafique, San Chae, Yong-Soo Kim
      Abstract: Modern Physics Letters B, Ahead of Print.
      Samples of pure zirconium (Zr) were irradiated by 18 MeV helium (He[math]) ions in the dose range 0.00162–0.0324 dpa at 373 K by using Cyclotron accelerator. The atomic force microscopy (AFM) results indicated an increase in average surface roughness of Zr by increasing the irradiation dose. The AFM images revealed nucleation and growth of nano- and micro-size hillocks at lower doses (0.00162–0.00324 dpa), whereas formation of a volcano-like cavities and craters was observed within these hillocks by increasing the radiation dose from 0.00324 to 0.0324 dpa. The high-resolution X-ray diffraction (XRD) results showed a variation in the intensities and positions of the diffraction peaks after the irradiation. The transmission electron microscopy (TEM) results reported a significant decrease in the grain size after the He[math] irradiation. The values of grain size, calculated using the TEM, were found to be in good agreement with the crystallite size calculated using the XRD analysis. The yield stress (YS) was increased by increasing the irradiation dose up to 0.0162 dpa, however, the YS exhibited a decreasing trend with a further increase of the dose. The changes in YS were elucidated by grain size reduction and localized heating at higher doses.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-11T08:26:21Z
      DOI: 10.1142/S0217984916503954
       
  • Enhanced ferromagnetic characteristics in Mn-doped ZnO: A promising
           diluted magnetic semiconductor
    • Authors: Muhammad Yousaf, Hafiz Muhammad Rafique, Muhammad Amin, Shahid Mahmood Ramay, Shahid Atiq
      Abstract: Modern Physics Letters B, Ahead of Print.
      Zn[math]Mn[math]O ([math] = 0, 0.02, 0.04, 0.06, 0.08 and 0.1) nanocrystalline diluted magnetic semiconductors (DMSs) were synthesized using sol–gel-based auto-combustion technique. X-ray diffraction (XRD) analysis of all the synthesized samples indicated pure wurtzite hexagonal structure without any secondary phase with perfect solubility of Mn contents in ZnO matrix. The increase in Mn concentration reduced the average crystallite size as evaluated by the Scherrer’s formula. Morphological analysis performed using a field emission scanning electron microscope (FESEM) indicated nearly an ordered surface morphology with some porosity and few cracks. Energy dispersive X-ray (EDX) spectroscopy confirmed the stoichiometric contents of Zn, Mn and O in each sample. Micrographs of all the samples exhibited a decrease in grain size with increase of Mn contents. Magnetic measurements performed using vibrating sample magnetometer (VSM) confirmed room temperature ferromagnetism exhibiting an increase in saturation magnetization and coercivity with increasing Mn contents in all the prepared samples.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-11T08:26:07Z
      DOI: 10.1142/S021798491650398X
       
  • Cooper pairs and bipolarons
    • Authors: Victor Lakhno
      Abstract: Modern Physics Letters B, Ahead of Print.
      It is shown that Cooper pairs are a solution of the bipolaron problem for model Fröhlich Hamiltonian. The total energy of a pair for the initial Fröhlich Hamiltonian is found. Differences between the solutions for the model and initial two-particle problems are discussed.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-10T01:19:33Z
      DOI: 10.1142/S0217984916503656
       
  • Hybrid driven three-terminal thermoelectric refrigerators
           based on resonant tunneling quantum dots
    • Authors: Zhicheng Shi, Weifeng Qin, Jizhou He
      Abstract: Modern Physics Letters B, Ahead of Print.
      In this paper, we propose a pair of symmetric three-terminal refrigerator models with a hot cavity connected to two colder reservoirs via ideal tunneling quantum dots. The cooling of the refrigerators is achieved by investing thermal power from a hot reservoir and electric power from an applied voltage. Based on the model proposed, we numerically analyze the performance of the refrigerators with different half width of energy levels, and particularly discuss the coefficient of performance for zero applied voltage in the limit of a small half level width. Finally, we optimize with half width of energy levels and get the optimal region of the refrigerators.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-04T06:26:40Z
      DOI: 10.1142/S0217984916503978
       
  • Research on transmission characteristics of side-coupled rectangular-ring
           resonator
    • Authors: Luna Cui, Li Yu
      Abstract: Modern Physics Letters B, Ahead of Print.
      We investigate the characteristics of resonant modes in the side-coupled rectangular-ring resonator (SRR). The results show we can manipulate the resonant wavelengths of [math] mode and [math] mode by adjusting the outer wall width (Lx1) or the inner wall width (Lx2) of the ring resonators, and the effects of coupling distance on the full-width at half-maximum (FWHM) of resonant spectra are discussed. In sensing application, the proposed structure can work as a highly sensitive plasmonic nanosensor with a sensitivity of 1000 nm/RIU and a figure of merit (FOM) of 67. The values are comparable to periodic structures and the structures based on Fano resonance.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-02T08:59:06Z
      DOI: 10.1142/S0217984916503747
       
  • Effects of active flux on plasma behavior and weld shape
           in laser welding of X5CrNi189 stainless steel
    • Authors: Hongbin Dai, Jun Peng
      Abstract: Modern Physics Letters B, Ahead of Print.
      In this paper, stainless steel was welded by active flux-aided laser welding method. The effects of single active flux (Cr2O3, SiO2 and TiO2) and composite active flux on laser welding were studied. In the welding process, laser plasma behavior was recorded by a high-speed imaging system. The results show that, with the addition of active flux, the absorption of laser energy and melting efficiency increase. In the laser power of 750 W, effects of active flux on weld depth to width ratio are given by the order: composite active flux [math] SiO[math] Cr2O[math] TiO2. The effect of composite active flux is the most significant and it can increase the weld depth to width ratio to 85%. Active flux can restrict the laser plasma. With the addition of composite active flux, the projected area of laser plasma obtained obviously reduced, and it can be reduced by 41.39%. Active flux cannot obviously change the main components in weld zone, but can change the grains of austenite and ferrite.
      Citation: Modern Physics Letters B
      PubDate: 2016-11-02T08:59:05Z
      DOI: 10.1142/S0217984916503759
       
 
 
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