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Controlling the corrosion rate of metal materials is one of the key issues in circulating cooling water treatment. In recent years, the treatment of circulating cooling water by microorganisms has become a research hotspot. Compared with the traditional chemical treatment, microbial treatment is an environmentally friendly technology. In this paper, the effects of ammonia nitrogen concentration, microbial dosage and aeration intensity on copper corrosion rate were studied. In order to analyze the experimental data more comprehensively, a full factor experimental design was used to investigate the effects of ammonia nitrogen concentration, microbial dosage and aeration intensity on copper corrosion. The corrosion rate of copper was less than the national standard (< 0.005 mm / a), in which ammonia nitrogen concentration and aeration intensity were significant factors (P < 0.05), and the interaction between ammonia nitrogen concentration and aeration intensity was also significant (P < 0.05), After optimization, the regression rate of the model increased from 85.02% to 92.41%.

This paper proposes a new structure of the negative capacitance field effect transistor (NCFET), which features of the dual ferroelectric region (DFR) when compared to the conventional NCFET. The dual ferroelectric region with FE1 region and FE2 region forms a non-uniform voltage amplification effect, leads to the significantly improvement of the gate control ability and modulates the electric characteristics of the NCFET. The mechanism of the voltage amplification effect, polarization reversal, channel surface electric field, and ferroelectric polarization intensity distributions are investigated. The influences of the ferroelectric parameters α and β on the electric characteristics are discussed. The results show that the DFR-NCFET is able to obtain a subthreshold swing (SS) below the Boltzmann limit (60 mV/dec) by increasing the ferroelectric parameter α of the FE2 region.

The microbial synthesized ZnS obtained from a pilot-scale sulfate reducing bacteria (SRB) fixed bed reactor was investigated as photocatalyst. The SRB fixed bed reactor as used to treat the Zinc containing wastewater with the influent concentration of 200~300 mg Zn/L. The microbial synthesized ZnS was used as photocatalyst for methylene blue (MB) photodegradation. The results indicated that the photodegradation process could be promoted when the dosage of microbial synthesized ZnS increased. High initial MB concentration could promote the photodegradation reaction. The excellent performance of microbial synthesized ZnS in photodegradation could be explained as the formation of ZnS nanoparticles. The photodegradation with microbial synthesized ZnS were simulated by pseudo-first-order kinetics model. The apparent first-order rate constant of the ZnS catalyst was 0.15 min-1.

With the increasing of service years, failure happens more frequently than before, which is consistent with the failure rate of equipment during the wear-out life period. On the base of continuous time Markov model for multi-state elements during the useful life period, aging factor is introduced to establish a non-homogenous continuous time Markov model during the wear-out life period. To obtain the reliability of a multi-state element, universal generating function is applied to combine its performance levels and probability functions. Through a combination operator determined by series-parallel logic relations, universal generating function of a multi-state system can be obtained. At last, a compressor of an engine is taken for example. The reliability of the system and its elements considering aging factor are relatively lower than that during the useful life period. And to maintain a reliability level at 80% under the demand of 50%, two days will be reduced from the planned maintenance cycle.DOI: http://dx.doi.org/10.5755/j01.mech.24.2.19183

Core flow experiment is an important means of simulation experiments to evaluate the effect of displacing agent, but conventionally the internal characteristics in the core cannot be intuitively observed, and then some important information can not be directly acquired by experiments. In this paper, a visualization method was used to detect the water-flooding process by using an improved low field nuclear magnetic resonance imaging (MRI) device, and the images describing the distribution of oil and water were collected. The experimental results show that the distribution of oil and water can be visually detected in an appropriate range of core porosity, and the end effect in many mechanics experiments is found to exist also in natural core flow test, and the influence range is about 0.004 m from the end of a 0.05752 m length natural core. The results also indicate that MRI is an effective tool to study the real time fluid distribution in natural core.

Water-based 10,12-pentacosadiynoic acid (PCDA)/ZnO nanocomposites with different concentrations of ZnO nanoparticles (0, 5, 10 and 15 wt%) have been successfully inkjet printed. The inkjet printing fabricated poly-PCDA/ZnO composites show reversible and stable chromatic properties at corresponding thermochromic transition temperatures. Attentuated Total Reflection (ATR)–Fourier Transform Infrared (FTIR) results suggest that the chelation between head groups on neighboring side chains of polymer and ZnO facilitates the release of stress on cooling from the red phase to rapidly form the blue phase. Moreover, by varying the concentration of ZnO, the chromatic properties of poly-PCDA/ZnO can be tailored to provide a simple way to apply poly-PCDA/ZnO for different thermal sensing applications.

A flexible reversible color change poly-(10,12-tricosadiynoic acid) TCDA-ZnO (2.5 wt%) composite based chromatic sensor was successfully designed and fabricated by inkjet printing. Fabricated sensors showed good reversibility and stable chromatic properties with color transition temperature at 70 °C. Attenuated Total Reflection (ATR) – Fourier Transform Infrared (FTIR) spectra show chelate formation between TCDA and ZnO. Temperature-dependent Raman spectra indicate that the blue-red phase of poly-TCDA-ZnO (2.5 wt%) is thermally triggered at 70 °C and the amorphous phase is formed near 120 °C. An inkjet printed Quick Response (QR) code using poly TCDA-ZnO demonstrates a sensory functionality which can be incorporated in these codes.

This study discussed the synthesis of LiFePO4/C materials prepared by carbonthermal reduction method and the characterization of obtained composites. X-ray diffraction patterns show the synthesized product is LiFePO4 phase without any existence of impurity. Scanning electron microscopic images show the synthesized LiFePO4 particle is nano sized, and carbon forms a conductive network between LiFePO4 particles. Transmission electron microscopy results indicate carbon successfully coated on the surface of LiFePO4 particles. Raman spectroscopy shows the coated carbon has low degree of graphitization. Compared with pure LiFePO4 samples, LiFePO4/C materials exhibit higher electronic conductivity and better electrochemical properties especially at high rate charge/discharge condition.

Non-stoichiometric compound fluoride-doped LiFePO4/C cathode materials were synthesized via solid-state reaction using MgF2 and AlF3 as dopant. The fluoride-doped LiFePO4/C samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical testing. The results show that the materials are well crystallized and fluoride doping cannot change the space structure of LiFePO4. Slight amounts of Fe2O3 with no fluoride impurity were detected. Charge-discharge curves show that fluoride-doped samples have higher capacity at low rates compared with undoped LiFePO4/C. AlF3-doped samples have highest capacity at high discharge current. Both doped samples have larger polarization voltage than undoped samples. All samples exhibit good cycle stability.

Despite the rarity, large negative linear compressibility (NLC) was observed in metal-organic framework material Zn(HO3PC4H8PO3H)∙2H2O (ZAG-4) in experiment. We find a unique NLC mechanism in ZAG-4 based on first-principle calculations. The key component to realize its large NLC is the deformation of H3O+ tetrahedron. With pressure increase, the oxygen apex approaches and then is inserted into the tetrahedron base (hydrogen triangle). The tetrahedron base subsequently expands, which results in the b axis expansion. After that, the oxygen apex penetrates the tetrahedron base and the b axis contracts. The negative and positive linear compressibility is well reproduced by the hexagonal model and ZAG-4 is the first MOFs evolving from non re-entrant to re-entrant hexagon framework with pressure increase. This gives a new approach to explore and design NLC materials.

We investigate the optical properties of Gaussian beams diffracted by a variable π-phase plate clinging tightly to the lens with long focal depth and its dependence on the size of the π-phase plate and the preset long focal depth of the lens. The numerical results show that the π-phase plate with appropriate size plus the multifunctional lens illuminated by Gaussian beam can produce bi-focus along the propagation direction and a center hollow light, and the distance between two focal planes along the longitudinal direction and the transverse and longitudinal spot size of the hollow beam will vary when changing the size of the π-phase plate or the preset long focal depth. This investigation indicates that the distance between the focal planes and the spot sizes of the hollow light can be controlled by the appropriately chosen size of the π-phase plate and the preset long focal depth of the lens. Furthermore, we compare the optical characteristics produced by three existing phase functions of the lens with long focal depth. It is expected that this investigation will provide useful information in various optical tweezers for operating and controlling.

We investigate second harmonic generation (SHG) in one-dimensional (1D) ferroelectric-metallic photonic crystals (PCs) which are composed of alternatively inverting poled ferroelectric domains with metallic insert layers. We observe a giant enhancement of SHG conversion efficiency due to high reflectivity of metallic layers, which form resonant cavities and lead to substantial increase of fundamental wave (FW) field in nonlinear medium layers.

The spontaneous emission (SE) behavior of the polarized atoms in a dielectric thin slab embedded in dielectric or metallic medium is analyzed. It is found that the SE rate of the polarized atoms in the vicinity of interface between the slab and surrounding medium can be considerably varied when changing the polarized direction of atoms. A switching operation of atomic SE between the inhibition and enhancement processes of the SE can be realized. In a dielectric thin slab embedded in metallic medium, the SE rate of the atoms near the dielectric–metal interface is enhanced greatly owing to the effect of surface-plasmon polaritons. Our findings imply that the tuning of the polarized orientation of atoms in the dielectric thin slab can effectively control the atomic SE processes.

According to new slip effects on nanopatterned interfaces, the mechanism of enhancing water injection into hydrophobic nanomaterial SiO2 was proposed. When hydrophobic nanoparticles (HNPs) are adsorbed on surfaces of porous walls, hydrophobic nanoparticles layers are formed instead of hydrated layer, and slip effects appear on the pore wall when a driving pressure is applied to the rock cores sample. It makes fluid to move more quickly and the flow capacity increases greatly. Experiments on changing wettability of porous walls were conducted, and the phenomenon that porous walls surfaces were adsorbed by nanoparticles was validated with the Environment Scan Electron Microscopy (ESEM). The results of displacement experiments show that flowing resistance is greatly reduced, and water-phase effective permeability is increased by 47% averagely after being treated by nanofluid. These results indicate that the slip effect may occur on nanoparticle film of porous walls. Based on this new mechanism of enhancing water injection about hydrophobic nanomaterial SiO2, a slip velocity model in uniform porous media was introduced, and some formulas for the ratio of slip length to radius, slip length, stream slip velocity and flux increment were deduced. and calculated results indicate that the ratio of slip length to radius is about 3.54%-6.97%, and the slip length is about 0.024μm -0.063μm. The proposed model can give a good interpretation for the mechanisms of enhancing water injection with the HNPs.

Transmissions of one-dimensional (1D) photonic crystals (PCs) containing multiple quantum wells with Gaussian-distributed refractive indices are calculated with the use of the transfer-matrix method. The transmission spectrum of this kind of structures exhibits flatted pass-bands. The resonant peaks in the transmission spectrum of the conventional 1D PCs have been significantly suppressed. It is expected that this kind of structures may favor the fabrication of optical filters in applications to micro-optical devices.

A new structure of negative-refractive-index material is proposed, which is composed of ferromagnetic wires setting in two-dimensional Bravais lattice (FWL) with the application of external magnetic field. The refractive index of the FWL consisting of ferrum wires arranged in square lattice is calculated. The refractive index exhibits negative value in the GHz region. A notable characteristic of the FWL is that the negative refractive index is tunable by the applied external field.

Band structures of two-dimensional photonic crystals (PCs) made of polar material with frequency-dependent dielectric constant are calculated by using an expanded basis method. The effect of the polariton gap (PG) of polar material on the photonic band gaps (PBGs) is explored. It is found that the PBGs are significantly modified near the PG, where the abrupt change of the dielectric constant appears. The feature of electromagnetic (EM) field is revealed when the frequency is located in the flat band. We display the equifrequency-surface configuration of the localized field and the spacial distributions of field. We observe the existence of several equi-ω curves for a specified frequency and the localized field distribution exhibiting various different patterns, dependent of the mode index. We also study the influence of the dielectric losses of the polar material on dispersion and find that the change of the real part of the Bloch wave vector is crucially related to the real part of the dielectric constant and the attenuated length is determined by its imaginary part.

The combined effects of Rashba spin-orbit interaction (SOI) strength and the length of SOI excited region, which can be controlled by the external gate voltage deposited on the heterostructure, and on the electron spin precession in quasi-one-dimensional quantum wires are investigated by evaluating the relative conductance change, i.e. the ratio of difference of the conductances of the spin-up and spin-down polarized electrons to the total conductance. It is found that for proper wire width, electron spin precession can be smoothly achieved by co-adjusting the SOI strength and the length of SOI excited region. However, for wide quantum wire and strong SOI, the electron spin precession is significantly reduced due to the appearance of inter-subband mixing.

We present a detailed investigation of the properties of the confined states in the photonic quantum-well (PQW) structures with the use of the transfer-matrix method. The influences of various physical and geometrical parameters of the systems on the characteristics of the confined states are systematically explored. The results show that the features of the confined modes can be engineered by adjusting system parameters. It may provide a useful way to control the merits of the defect modes in order to match the requirements in photonic or microwave devices.

We calculate the omnidirectional dispersion spectrum for one-dimensional (1D) photonic crystals (PCs) inserting multiple photonic quantum-wells (PQWs) with the use of the plane-wave expansion method in combination with a supercell technique. We find that the localized defect modes significantly depend on the number of the PQWs and the configuration. This may provide a new way to engineer the dispersions of the composite PCs to meet the requirements of optical or microwave devices.

Using an efficient expanded basis method, we have studied the effects of Rashba spin–orbit interaction (SOI) and a laterally inhomogeneous magnetic field on the eigenstates of spin-polarized electrons in a quantum wire. Our numerical results show that inhomogeneous magnetic field can significantly modify the energy spectrum as compared with uniform magnetic field. The spatial distributions of probability and spin densities across the wire have also been investigated. We find that in the presence of only Rashba SOI, i.e., without magnetic field, the component of spin density parallel to the propagating direction vanishes for all the states and the other two spin components exhibit even (or odd) symmetry and oscillating behaviors across the wire. Under the interplay of Rashba SOI and nonuniform magnetic field, the distributions of both the probability and spin densities show a variety of localized behavior. The spin polarizations of electrons strongly depends on the wave number of the propagating state.

The focusing action of refractive cylindrical microlens is investigated based on the rigorous electromagnetic theory with the use of the boundary element method. The focusing behaviors of these refractive microlenses with continuous and multilevel surface-envelope are characterized in terms of total electric-field patterns, the electric-field intensity distributions on the focal plane, and their diffractive efficiencies at the focal spots. The obtained results are also compared with the ones obtained by Kirchhoff's scalar diffraction theory. The present numerical and graphical results may provide useful information for the analysis and design of refractive elements in micro-optics.

We present numerical calculations of the energy dispersion of spin-polarized electrons in quasi-one-dimensional electronic waveguides in the presence of Rashba spin–orbit interaction (SOI), by using an efficient expanded basis method. Within this model, the general mixing between any two subbands is taken into account. We investigate the properties of spin-polarized transport in the nonuniform SOI system. It is found that the multi-band mixing brings significant effects on the properties of multiple subbands transport in the regime of high energy, especially for the cases of the wide waveguide, the strong SOI and the long extension of the SOI region.

We investigate the intersubband-transition rates of in-gaps electrons assisted by localized-interface-optical-phonons (LIOPs) in AlAs/GaAs SL with a defect layer for different widths and different materials of defect layer and constituent layers. The rates are calculated under Fermi's golden rule and by using transfer-matrix method and on the basis of the dielectric continuum theory. The dependence of the maximum transition rate on the energy spacing between the initial and final states of in-gaps electrons, involving different LIOP modes is revealed. The results show that the intersubband-transition rates between the in-gaps states of electrons significantly depend not only on the structural configurations of the defect layer but also on physical and geometrical parameters of the systems as well as nature of the LIOP modes involved in the transition processes.

Coatings of W on the substrate of oxygen-free Cu have been made by a high efficiency supersonic plasma spray system with a maximum power of 80kW and a maximum working at 6 m3/h flow of gas, and being compared with results of subsonic plasma spray. The bonding strength and thermal shock resistance of the coatings was tested. W/Cu functionally graded coatings is compared with single coatings of W.

We investigate the evolution of the band gap in one-dimensional (1D) photonic crystals (PC) with the gradual modifications of structural configurations from photonic quantum wells to PC heterostructures. The transmissive spectra are calculated with the use of scattering matrix method. We find that the transmissive spectra and confined states strongly depend on the structural configurations of samples.

Two-dimensional tunable photonic crystals (TPCs) with movable components are proposed, which consist of a circular dielectric rod inserted into a square lattice of square dielectric cylinders in air. The band gap structures of TPCs can be tuned by adjusting the shift of the position of the circular rod in each unit cell. Band gap structures are calculated with the use of the plane-wave expansion method for various structural parameters, such as different filling fractions, ratio of the radius of the circular rod to the side-length of the square cylinder, different shifts or shifting orientations of the circular rod, etc. We find that there is a region of parameters in which the ratio of the gap width to the midgap is insensitive to the shift of the position of the circular dielectric rod. It is anticipated that the proposed TPC may become a favourable candidate of PCs owing to the benefit of facilitating fabrication, allowing a large tolerance.

We present numerical studies of conductance of quasi-particles (QPs) in junctions consisting of semiconductor (Sm) two-dimensional electronic gas (2DEG) and superconductor (S) containing a finite w...

Numerical analysis of the conductance of quasi-particles (QPs) is presented for two-dimensional (2D) L-shaped bent quantum waveguide (LBQW) with the application of inhomogeneous magnetic fields and a semiconductor–superconductor (Sm–S) junction at the exit arm. A δ -function scattering potential is placed at the Sm–S interface to simulate the imperfectness of the Sm–S interface. The conductance of the QPs as a function of magnetic field strongly depends on normal or superconducting state of the material at Sm–S junction. The conductance displays increasing behavior at the beginning and then it exhibits oscillatory decay. This implies that the Andreev reflection (AR) plays an important role on the conductance. As increasing the magnetic field, the conductance is decreased accordingly as the normal reflection is significantly enhanced and meanwhile the AR becomes imperfect. We also reveal the effects of various physical and geometrical parameters of system on the conductance in detail.

We study the properties of the localized interface plasmon modes (IPMs) arising from coupling and splitting of the plasmon eigenstates in two semi-infinite superlattices containing complex defect structures. Two kinds of defect structure are considered: one is a single quantum well, i.e., a barrier–well–barrier structure; the other is a well–barrier–well structure. The influences of the constitution of the defect structures, as well as the physical and geometric parameters of the superlattices on the characteristics of the localized IPMs are investigated in detail. The numerical results show that the localized modes exhibit peculiar features; the complexity of the dispersion of IPMs is essentially associated with the coupling of the interwell regions in the defect structure, and the barrier and well layers play different roles in the features of the localized IPMs. We also present a comparison of the dispersions of the localized IPMs between these two types of defect structure and give a physical picture to explain these results.

In the framework of random-phase approximation theory and applying the self-consistent field method, we study the properties of collective charge density excitations in single quantum well in consideration of dielectric mismatch. We analytically give the general solution of the image potential to the one dimensional Green's function. Our numerical results demonstrate that the dielectric mismatch between the barrier and well materials significantly changes the frequency of the intra- and inter-subband plasmon modes in contrast with dielectric match. We reasonably conclude that the image potential affects the intra- and inter-subband plasmon modes in a different way.

In the dielectric continuum approximation, we study the effect of different styles of coupling on the localized interface optical-phonon modes in two coupled semi-infinite N-constituent superlattices with a structural defect layer. The defect layer is composed of frequency-dependent or frequency-independent dielectric medium. The influence of the material and structural parameters of the defect layer on the localized interface optical-phonon modes is investigated in detail. Our results show that the localized modes exhibit peculiar characteristics in multi-constituent superlattices with a defect layer, substantially different from those of the conventional dual-constituent sample. A simple physical picture is presented to explain these results.

We have studied second-harmonic generation (SHG) from quasi-one-dimensional aperiodic optical superlattices (AOSs) of finite lateral width by inverting poled ferroelectric domains. The search for optimal AOS structures corresponds with solving a difficult inverse source problem. We describe the design principle in real-space representation and undertake model designs. The numerical simulations show that the constructed AOSs can implement multiple-wavelength SHG with identical effective nonlinear coefficients at the pre-assigned wavelengths of the incident light. We investigate the effects of mode–mode coupling and the lateral width of the superlattice on the SHG for two cases: incident light beams of plane-wave and Gaussian profiles. When the number of modes increases, the effective nonlinear coefficient decreases in an oscillatory fashion at the beginning and then tends to a constant. For an incident plane-wave beam, the dependence of the effective nonlinear coefficient on the width of the sample is quite weak, while for an incident Gaussian beam this dependence exhibits a rapid decrease at the beginning and then tends to a constant. We display the variation in the effective nonlinear coefficients with the distance of propagation of the optical wave from where the incident light beam impinges on the sample surface and find that this variation exhibits monotonically increasing behaviour. This clearly infers that the contribution of every block to the optical SHG process takes the form of constructive addition. It is expected that this new design method may provide an effective and useful technique for constructing nonlinear optical material to match various practical applications.

The oscillatory characteristics of magnetoconductance for a junction composed of a superconductor and a semiconductor, in which two parallel quantum wave guides are coupled with each other through a potential barrier layer, are studied systematically. To model the imperfectness of the interface, we introduce a $\delta-$ function scattering potential barrier lying close to the interface of the junction. The magnetoconductance oscillations (MCO) in this system stem from two sources: one is the interference of wave functions of quasi-particles due to multiple Andreev reflections at the interface; the other is attributed to the variation of the number of the propagation modes when introducing the isolating barrier layer. The introduction of the isolating layer in the quantum wave-guides strongly modifies MCO. We also present a physical picture for the MCO based on a phenomenological argument. The theoretically fitted results are in good agreement with numerical ones.

We investigate the properties of guide modes localized at the interfaces of photonic crystal (PC) heterostructures which are composed of two semi-infinite two-dimensional PCs consisting of non-circular air cylinders with different rotating angles embedded in a homogeneous host dielectric. Photonic band gap structures are calculated with the use of the plane-wave expansion method in combination with a supercell technique. We consider various configurations, for instance, rectangular (square) lattice–rectangular (square) air cylinders, and different rotating angles of the cylinders in the lattices on either side of the interface of a heterostructure. We find that the absolute gap width and the number of guide modes strongly depend on geometric and physical parameters of the heterostructures. It is anticipated that the guide modes in such heterostructures can be engineered by adjusting parameters.

We first investigate the band gap structures of two-dimensional magnetic photonic crystals (MPC) composed of rectangular (square) magnetic cylinders embedded in a host dielectric material in the rectangular (square) lattice, and we then study guide modes at interface of MPC heterostructures (MPCHs) by use of plane wave expansion method in combination with supercell technique. We find that both the mirror-symmetric MPCHs and the mixed-type MPCHs composed of square cylinders in a square lattice can produce the TM guide modes even without any lattice distortions. This feature is quite different from that of the non-magnetic PC heterostructures, in which the occurrence of the guide modes requires the relatively longitudinal gliding or transverse displacement of lattices. It may provide a new way to generate guide modes and apply to the device of light wave guides.

We investigate the existence and characteristics of the localized interface optical phonon modes (IOPMs) in a semi-infinite AlAs–GaAs superlattice with a cap layer consisting of ternary mixed crystal Alx Ga1−x As in the dielectric continuum approximation. We find that the introduction of two-mode behaviour of the ternary mixed crystal of the cap layer or the semi-infinite uniform dielectric medium leads to rich and varied localized mode spectra with interesting features. Moreover, it is also found that the localized IOPMs are sensitive to the concentration x, the thickness of the cap layer and the type of semi-infinite uniform dielectric medium. A brief analysis of these results is given. It is expected that the localized IOPMs can be artificially controlled by adjusting the parameters of the proposed micro-structures.

We investigate the effects of spatial asymmetry, tunneling coupling, and exchange-correlation correction on the plasmon modes in asymmetric double quantum well (DQW) structures in a time-dependent local-density approximation. Special attention is paid to the properties of the ω - mode which is always damped in symmetric DQW systems. In addition, the results on the spectral weight of the excitations are also presented. In general, all the modes carry finite spectral weights and should be observable in resonant inelastic light scattering experiments for the specified values of the parameters.

We investigate the property of the localized mixed acoustic modes lying in the interior minigap in structural defect superlattices grown away from the cubic axis of bulk materials. It is found that the localized mixed modes always appear in pairs inside each interior minigap for certain structural parameters. Furthermore, there are degeneracy points between two branches of localized mixed modes. These characteristics are markedly different from localized folded acoustic phonon modes in minigaps that occur at the center and the edge of the Brillouin zone. We also find that the interior minigap and localized mixed modes strongly depend on the growth direction of the superlattices.

Using a special flyer-inclined target, the dynamic characters of a flyer were investigated experimentally for the first time. On the basis of the observation of the shock luminescent signal from the rear surface of a target impacted continuously by the flyer, it appears that the flyer has a steady flying velocity of ∼30.3 km/s after flying a distance longer than ∼30 μm at irradiance of ∼0.8×1014 W/cm2. An experiment on the effect of increasing pressure with the flyer technique was also carried out, and showed that the shock pressure obtained with a flyer was six times more than that without a flyer.

We present numerical investigations of the transmission properties of electrons in a normal quantum wire tangentially attached to a superconductor ring threaded by magnetic flux. A point scatterer with a δ -function potential is placed at node to model scattering effect. We find that the transmission characteristics of electrons in this structure strongly depend on the normal or superconducting state of the ring. The transmission probability as a function of the energy of incident electrons, in the case of a superconductor ring threaded by one quantum magnetic flux, emerges one deep dip, imposed upon the first broad bump in spectrum. This intrinsic conductance dip originates from the superconductor state of the ring. When increasing the magnetic flux from one quantum magnetic flux to two, the spectrum shifts toward higher energy region in the whole. This conductance dip accordingly shifts and appears in the second bump. In the presence of a point-scatterer at the node, the spectrum is substantially modified. Based on the condition of the formation of the standing wave functions in the ring and the broken of the time-reserve symmetry of Schrodinger equation after switching magnetic flux, the characteristics of transmission of electrons in this structure can be well understood.

Lithium iron phosphate with the structure of olivine has many advantages: low price, environmentally friendly, great thermal stability and excellent cycle performance when used as the anode materials, making it one of the most promising anode materials. In this article, we used the precusor FePO4 pre-prepared to produce LiFePO4 and the performances were tested. The process of preparation of the precusor FePO4 were optimized and the reaction mechanism was probed into. The precusor FePO4 was prepared by the raw materials as follows: ferric nitrate, phosphoric acid and diammonium hydrogen phosphate, the temperature, PH, Fe/P and the time of reaction were considered. LiFePO4 was prepared by calcining the mixture of iron phosphate, lithium carbonate and glucose after mixed. The test of charge-discharge indicates that the sample of LiFePO4 holds the discharging voltage platform 3.4 V, the first charge-discharge specific capacity under 0.1C are 164.6 and 163.6 mAh/g respectively.

The analytic solution to the wave equation for small-signal sum-frequency process is derived in 2D χ (2) photonic crystals with use of the Green function method. It is predicted that the sum-frequency electrical field at quasi-phase matching (QPM) resonance is proportional to the angle-dependent effective crystal length. This implies that multiple wavelength QPM frequency conversion with controllable intensity output can be realized in a single 2D χ (2) photonic crystal. It is revealed that efficient frequency conversion requires both the QPM and the proper structure matching. A novel double-circle construction, different from the conventional Ewald construction, is presented to reflect important QPM processes. It is also shown that the QPM resonance tuning of second-harmonic generation can operate over the whole transparent wavelength range of crystals.

The photonic band structures of two-dimensional photonic crystals consisting of lattices with different symmetries and scatterers of various shapes, orientations, and sizes are studied numerically. Specifically, four types of lattices (triangular, hexagonal, square, and rectangular) and five different shapes of scatterers (hexagon, circle, square, rectangle, and ellipse) are considered. The scatterers are either dielectric rods in air, or air rods in dielectric media. The lattice symmetry and all these properties of the scatterers can affect the band gap size. Given a lattice symmetry, the largest absolute photonic band gap is achieved by selecting a scatterer of the same symmetry; e.g., hexagonal rods in triangular or honeycomb lattices, square rods in square lattices, and rectangular rods in rectangular lattices. The band gap can be further maximized by adjusting the orientation and size of the scatterers; but no simple, systematic rules can be drawn.

The collective charge density excitations in asymmetric double-quantum-well (DQW) structures with different tunneling strengths are systematically studied. In particular, the damping properties of the plasmon modes in various tunneling strengths are investigated in detail. It is shown that plasmon modes in asymmetric DQW structures are quite different from those in symmetric DQW systems. In weak tunneling regime, an intra-subband mode ω- with an acoustic-like dispersion relation which is damped in symmetric DQW structures arises and coexists with the optical-like mode ω+ while the inter-subband mode ω10 is highly damped. With the tunneling strength being increased, the ω10 branch gradually becomes undamped and emerges out of the (1-0) single-particle continuum, whereas the ω- branch gradually approaches the (0-0) single-particle continuum. In intermediate coupling regime, these three branches of modes coexist undamped. In strong tunneling regime, ω- enters the (0-0) single-particle continuum and becomes damped. Consequently, only the ω+ and ω10 modes exist in this regime.

We report a theoretical study of the spectral statistics of a quasi-one-dimensional surface superlattice in perpendicularly applied magnetic fields. The energy-level-spacing distribution and the Dyson–Mehta Δ3 statistic of the magnetic band structure of the system are calculated. The calculations show that for the system with inversion symmetry, the magnetic band structure at the wave vector k = 0 is well described by the statistic derived by a superposition of two independent Gaussian orthogonal ensemble (GOE) statistics. This result is consistent with the fact that the system shows a false time-reversal violation and a real-space symmetry. The calculations show also that when the wave vector k is moved away from the k = 0 point, the statistical properties of the magnetic band structure are excellently described by the GOE statistics. The GOE statistics are also found in the magnetic band structure when the inversion symmetry is removed from the system.

We present a theoretical study of the phase property of the transmission coefficient of a quantum dot. We model the quantum dot by a cross-bar structure and take account of electron-electron interactions in the dot in a self-consistent mean-field approximation. We find that the phase acquired by electrons traversing the dot increases smoothly by π along a resonance peak and drops abruptly by π in the tail of the resonant peak, where the probability of the transmission vanishes. We also show that this sharp phase change cannot be seen in a model that assumes a single-particle, double-barrier structure only for the quantum dot.