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A high reliable and low noise frequency synthesizer was designed and manufactured by 0.18um SiGe BiCMOS process. The innovation of this paper is to use HBT with better 1 / f noise performance to replace MOS transistor to obtain better noise performance. The frequency synthesizer circuit is capable of producing 1.7GHz-2.3ghz RF output signal (one of the VCO output bands); The operating frequency of the frequency synthesizer is 800MHZ-5GHZ. The normalized phase noise of the frequency synthesizer reaches −230 dBc /Hz.

Our experimental scheme is based on a barrel optical microcavity filled with a dye solution. It is found that the number of non-condensed photons is characterized by an analytical function, which involves a q-digamma function in mathematics. We employ the q-digamma function to calculate the spatial and momentum distributions of ideal photons in a one-dimensional barrel cavity. The first main finding in this paper is that the spatial and momentum distributions possess a similar profile. The second main finding is that when photons are in the normal state, the density profile exhibits Friedel oscillations. The third main finding is that when photons are in the BEC state, the density profile exhibits a sharp peak with extremely narrow width. The fourth main finding is that the central peak of the density distribution is a monotonically increasing function of the photon number N but is a monotonically decreasing function of the temperature T.

The geometrical, electronic, and optical properties of superhard structures tP10-FeB4 and I4 1 /acd-FeB4 have been investigated using different density functional theory (DFT) approaches. The geometrical and electronic properties were calculated using DFT with projector augmented wave pseudopotentials. To obtain reasonable fundamental bandgaps and optical properties, we performed post-DFT calculations by solving the Bethe–Salpeter equation (BSE) based on Green’s function calculations. The absorption, reflectivity, refractivity, and photoconductivity were calculated, analyzed, and compared with results available in literature. The results of the BSE method show that the optical properties of both the tP10-FeB4 and I4 1 /acd-FeB4 structures demonstrate several novel characteristics, implying they are potential optical materials with various applications.

High frequency is the development trend of switching power supplies to achieve miniaturization density of switching power supplies. However, the increase in frequency makes the leakage inductance parameter of the transformer in the switching power supply more and more important to the performance of the circuit. In this paper, the leakage inductance and winding loss of high frequency transformer in LLC resonant converter are analyzed in detail. An optimized design scheme of high frequency transformer based on winding structure is introduced, which can effectively reduce the leakage inductance and winding losses of high frequency transformer, and improve stability and efficiency of the transformer resonant converter. Finite-element analysis simulation validate the design scheme.

LLC resonant converter typically works in Pulse Frequency Modulation (PFM) mode. The output voltage can be adjusted by adjusting the switching frequency of the converter. In order to meet wide voltage variation and various load conditions, the switching frequency of LLC converter must be changed in a wide range, which brings great difficulties to the design of high frequency transformer and the selection of power devices. Based on the analysis of the relationship between dead-time and operating characteristics of LLC resonant converter, this paper establishes the mathematical relationship between resonant tank gain and dead-time of LLC resonant converter, and makes theoretical analysis and experimental verification. The results show that without increasing the gain of the converter, increasing the dead-time appropriately can reduce the switching frequency range of the converter, thus reducing the design difficulty and the switching loss of the converter.

Therapeutic proteins are a developing part of the modern biopharmaceutical industry, providing novel therapies to intractable diseases including cancers and autoimmune diseases. The human embryonic kidney 293 (HEK293) cell line has been widely used to produce recombinant proteins in both basic science and industry. The heterogeneity of glycan structures is one of the most challenging issues in the production of therapeutic proteins. Previously, we knocked out genes encoding α1,2-mannosidase-Is, MAN1A1, MAN1A2 and MAN1B1, in HEK293 cells, establishing a triple-knockout (T-KO) cell line, which produced recombinant protein with mainly high-mannose-type N-glycans. Here, we further knocked out MAN1C1 and MGAT1 encoding another Golgi α1,2-mannosidase-I and N-acetylglucosaminyltransferase-I, respectively, based on the T-KO cells. Two recombinant proteins, lysosomal acid lipase (LIPA) and immunoglobulin G1 (IgG1), were expressed in the quadruple-KO (QD-KO) and quintuple-KO (QT-KO) cell lines. Glycan structural analysis revealed that all the hybrid-type and complex-type N-glycans were eliminated, and only the high-mannose-type N-glycans were detected among the recombinant proteins prepared from the QD-KO and QT-KO cells. Overexpression of the oncogenes MYC and MYCN recovered the slow growth in QD-KO and QT-KO without changing the glycan structures. Our results suggest that these cell lines could be suitable platforms to produce homogeneous therapeutic proteins.

Polarization diversity can improve channel capacity and reduce signal fading. This paper proposed a dual-polarized monopole antenna with simple structure for polarization diversity system. The proposed antenna was composed of inverted-F antenna and inverted-L antenna, which were orthogonally mounted in space. The planar mental plate was used to obtain the unidirectional patterns. The frequency range of discussed antenna was from 2.35GHz to 2.55GHz. The antenna structure was designed and simulated by full-wave electromagnetic simulation technology. The designed dual-polarized monopole antenna had an analog voltage standing wave ratio (VSWR) of less than 2, and the relative frequency band was about 8.16%. The axial ratio (AR) of each polarization port at the boresight for the designed antenna was higher than 20dB. For each port, the wide beam was achieved, which was suitable for the array antenna application. What’s more, the antenna miniaturization was also realized. The proposed dual polarization antenna had simple structure, low cost and was suitable for engineering application.

Because of the high water flux and excellent ion rejection, the pores graphene is considered as a promising candidate material for fabricating the membranes in reverse osmosis (RO) process. Unfortunately, water molecules cannot pass through the perfect graphene, and how to effectively create a large number of nanopores with controllable size remains a challenge, which seriously prevents the practical application and development of graphene membrane for desalination. Recently, the emergence of pillared graphene (PGN) might open a new way for designing the graphene-based membranes, which can compensate for the deficiency of porous graphene membrane. The PGN has been extensively studied in gas storage and separation, and its RO characteristics and mechanism still remain unclear because the limitation of large area preparation in desalination. In this paper, the RO process of seawater through PGN membranes is investigated by molecular dynamics simulations, and the influences of the pressure within feed solution, temperature and the shearing of membrane on the desalination properties are considered. It is found that the water flux increases linearly with the pressure within feed solution increasing, and the PGN membrane with nanopore diameter of 0.8 nm can conduct water molecules but completely rejects high-concentration ions. As the diameter of nanopores increases to 1.2 nm, the rise of temperature can increase the permeability of water molecules, whereas the salt rejection is not appreciably sensitive to the temperature. Particularly, the shearing membrane can improve the salt rejection and hinder the water molecules from permeating at the same time. The designed PGN membrane exhibits excellent performance of water purification, and the ultrahigh water flux obtained in this work reaches 56.15 L·cm–2·day–1·MPa–1 with a salt rejection of 88.9%. Subsequently, the hydrogen bond dynamics is calculated in order to explain the variation of water permeability under different conditions. The result shows that the rise of temperature reduces the stability of hydrogen bonds and leads the water flux to increase, while the increase of shearing speed will enhance the stability of hydrogen bonds and inhibit water seepage. Furthermore, the analysis results of hydrogen bond and ionic hydration structure show that the shear motion on RO membrane will improve the stability of ionic hydration shell, which makes it more difficult for the ions to pass through nanopores by weakening the hydration shell. On the contrary, rising temperature will impair the strength of ionic hydration shell, leading more ions to pass through the RO membrane. The simulation results can provide an in-depth understanding of the desalination performance of PGN membrane under different key conditions, and further demonstrate the promising applications of graphene-based membrane in water desalination.

The Hartree–Fock–Popov theory of interacting Bose particles is generalized to the Cooper-pair system with a screened Coulomb repulsive interaction in high-temperature superconductors. At zero temperature, it is found that the condensate density $$n_c(0)$$ of Cooper pairs is of the order $$n_c(0)\simeq 10^{18}$$ cm $$^{-3}$$ , consistently with the fact that a small fraction of the total p holes participate in pairing. We find that the phonon velocity c(0) at zero temperature is of the order $$c(0)\simeq 10$$ km s $$^{-1}$$ . The computation shows that the transition temperature $$T_c$$ is a dome-shaped function of the p hole concentration $$\delta $$ , which is consistent with experiments. At finite temperature, we find that the condensate fraction $$n_c(T)/n$$ decreases continuously from $$n_c(0)/n$$ to zero as the temperature increases from zero to the transition temperature $$T_c$$ . For higher temperatures, we find that the repulsive interaction between Cooper pairs drives more Cooper pairs into the condensate. The computation reveals that the phonon velocity c(T) decreases continuously from c(0) to zero as the temperature increases from zero to the transition temperature $$T_c$$ . The Cooper-pair system undergoes a first-order phase transition from the normal state to the BEC state.

An ultra-compact chiral metamaterial (CMM) using triple-layer twisted split-ring resonators (TSRRs) structure was proposed, which can function as a multi-band circular polarizer. This ultra-compact structure CMM can convert an incident linearly y-polarized (x-polarized) wave propagating along thez(+z) direction to the transmitted left circularly polarized (LCP) waves at 7.28 GHz, 13.22 GHz and 15.49 GHz while the right circularly polarized (RCP) waves are at 9.48 GHz simultaneously. In addition, the large polarization extinction ratio (PER) of more than 20 dB across four resonance frequencies can be achieved. The experiment results are in good agreement with the numerical simulation results. The surface current distributions of the structure are analyzed to illustrate this linear to circular polarization conversion. The unit cell structure is extremely small both in longitudinal and transverse directions. Good performances and compact design of this CMM suggest promising applications in circular polarizers that need to be integrated with other compact devices.

With the development of power electronics technology, compared with AC and DC power distribution network, the energy router has tremendous potential for its obvious advantage and make a significant contribution to the energy internet. Firstly the key devices of the energy router is discussed and the network framework of the small energy router in user layer is proposed. Then the research status of isolated bidirectional DC/DC converter(IBDC) is reviewed systematically. Subsequently the circuit topology of dual-active-bridge(DAB) and resonant full-bridge are analyzed in detail, the corresponding control strategies are studied and the characteristics of above mentioned converters are also summarized. Finally the key issues of the power electronic transformer(PET) or solid state transformer(SST) to be solved urgently are also pointed for energy router application. Conclusions will provide essential theoretical and practical basis for industry application of future energy router.

We present a simple design for a broadband tunable terahertz (THz) metamaterial absorber (MMA) consisting of a complementary cross-oval-shaped graphene (CCOSG) structure and dielectric substrate placed on a continuous metal film. Both numerical simulation and theoretical calculation results indicate that the absorbance is greater than 80% from 1.2 to 1.8 THz, and the corresponding relative bandwidth is up to 40%. Simulated electric field and power loss density distributions reveal that the broadband absorption mainly originates from the excitation of continuous surface plasmon resonance (SPR) on the CCOSG. In addition, the MMA is polarization-insensitive for both transverse-electric (TE) and transverse-magnetic (TM) modes due to the geometry rotational symmetry of the unit-cell structure. Furthermore, the broadband absorption properties of the designed MMA can be effectively tunable by varying the geometric parameters of the unit-cell and chemical potential of graphene. Our results may find promising applications in sensing, detecting, and optoelectronic-related devices.

We applied the reduced graphene oxide/multi-walled carbon nanotubes/nickel oxide (RGO/MWCNTs/NiO) nanocomposite as the counter electrode (CE) in dye-sensitized solar cells (DSSCs) on fluorine-doped tin oxide substrates by blade doctor method. Power conversion efficiency (PCE) of 8.13 % was achieved for this DSSCs device, which is higher than that of DSSCs devices using NiO, RGO, and RGO/NiO-CE (PCE = 2.71 %, PCE = 6.77 % and PCE = 7.63 %). Also, the fill factor of the DSSCs devices using the RGO/MWCNTs/NiO-CE was better than that of other CEs. The electron transfer measurement of cyclic voltammetry and electrochemical impedance spectroscopy showed that RGO/MWCNTs/NiO film could provide fast electron transfer between the CE and the electrolyte, and high electrocatalytic activity for the reduction of triiodide in a CE based on RGO/MWCNTs/NiO in a DSSC.

In this paper, we fabricated nickel oxide nanofilament/multiwall carbon nanotubes (NiO-NF/MWCNT) nanocomposite by a simple hydrothermal synthesis method as a counter- electrode (CE) in a dye-sensitized solar cell (DSSC). Transmission electron microscopy, scanning electron microscopy images and X-ray diffraction analysis clearly indicated the formation of NiO-NF/MWCNT nanocomposite. The electro-chemical properties of NiO-NF/MWCNT CE are studied by cyclic voltammetry and electrochemical impedance spectroscopy. In particular, current-voltage measurements indicated superior power conversion efficiency (PCE) of 7.63% of the NiO-NF/MWCNT CE compared to 6.72% for the platinum (Pt). The superior photovoltaic performance and low cost of the NiO-NF/MWCNT nanocomposite can be potentially exploited as a new counter-electrode in DSSCs.

In view of the LLC series resonant converter topology, it is well known as suitable for small and medium power application, the stabilization of output voltage and the environment of step-dowm. The scheme is proposed for a kind of the step-up DC/DC transformer based on LLC resonant full bridge. The detailed design method is given. The 3KW prototype is built. The experimental results show it has the characteristics of the constant current discharge, wide working frequency and high power desity, as well, the feasibility is verified.

A graphene-based nanosheet composite/multiwalled carbon nanotube/polyaniline (GNS/MWCNT/PANI) was synthesized via an in situ polymerization technique and applied by the spin-coating method as a counter electrode (CE) in dye-sensitized solar cells (DSSCs). The combination of the high catalytic activity of PANI and outstanding conductivity of GNS/MWCNT improved the photovoltaic performance of the hybrid CE. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) showed that the GNS/MWCNT/PANI composite has high catalytic activity for the reduction of triiodide to iodide and low charge-transfer resistance at the electrolyte/electrode interface. Transmission electron microscopy (TEM) images showed that the GNS/MWCNT/PANI-CE has a rough and porous structure and X-ray diffraction analysis confirmed the formation of PANI coating on the surface of the GNS/CNT. In particular, current–voltage measurements showed the superior power conversion efficiency (PCE) of 7.52% of the DSSC based on GNS/MWCNT/PANI-CE compared to the PCE of 6.69% of the DSSC based on Pt-CE.

In this paper, a bi-layer twisted split-ring structure asymmetric chiral metamaterial was proposed, which could achieve circularly polarized (giant circular dichroism efiect) wave with dual bands and linear polarization transformation (giant optical activity) with asymmetric transmission wave emissions simultaneously from linearly polarized incident wave at microwave frequencies. Experiment and simulation calculations are in good agreement, indicating that the dual-band circular polarizer features high conversion e-ciency around 5.32GHz and 6.6GHz in addition to large polarization extinction ratio of more than 16dB, while cross linear polarization transformation with asymmetric transmission is observed around 10.52GHz. The transformation behavior for both circular and linear polarizations could be further illustrated by simulated surface current and electric fleld distributions. The proposed asymmetric chiral metamaterial structure could be useful in designing novel EM or optical devices, as well as polarization control devices.

Bose–Einstein condensation (BEC) of dressed photons in a Kerr nonlinear optical microcavity is investigated. Our experimental scheme is based on an optical microcavity filled with a Kerr nonlinear nonpolar crystal. The pump photons interact with the Raman phonons in the crystal and hence are converted into new quasiparticles, which we refer to as dressed photons. A dressed photon is a photon dressed with a cloud of virtual transverse-optical phonons. The first main finding is that two-dimensional (2D) dressed photons have an increased inert mass. The second main finding is that the lower cutoff frequency of a nonlinear optical microcavity becomes larger. The third main finding is that the incident laser intensity is a moderate laser intensity ([Formula: see text]10[Formula: see text] W/cm2). The fourth main finding is that the critical optical power of a nonlinear optical microcavity is increased. The fifth main finding is that the radiation emitted by 2D dressed photons has an ultrahigh intensity.

A bright green photoluminescence of Er3+:YVO4 single crystal, excited by 407.6 nm femtosecond laser, was investigated under pulsed magnetic field up to 47 T. The integrated photoluminescence (PL) intensity is enhanced as magnetic field increases and reaches the maximum at around 4.5 T, while further increasing of magnetic field up to 47 T will suppress the PL intensity. And similar profile was observed in magnetic field dependent absorbance at excitation wavelength. These results are different from the reported literatures, detailed study here helps us to better understand the effect of magnetic field on Er doped materials and points out an efficient way to modulate the optical properties of luminescence materials which is important for the design and optimization of future devices.

In this paper, a multi-band chiral metamaterials (CMMs) based on complementary cross-wire structure is proposed and studied numerically. The finite element method (FEM) method was used to simulate the EM properties of the designed structure. Numerical results indicate that the giant optical activity and multiband negative refractive index can be realized in terahertz region. The proposed CMMs may have some potential applications in novel terahertz device.Particle size of bayerite (d50) was about 24 μm. Al2O3was obtained after calcination at 1050 °C for 1.5 h.

The Hartree–Fock–Popov theory of interacting Bose particles is generalized to the Cooper-pair system with a screened Coulomb repulsive interaction in high-temperature superconductors. At zero temperature, we find that the condensate density n c ( 0 ) of Cooper pairs and the phonon velocity c ( 0 ) are dome-shaped functions of the p hole concentration δ. At finite temperature T, we find that the condensate fraction n c ( T ) / n and the phonon velocity c ( T ) decrease continuously from n c ( 0 ) / n or c ( 0 ) to zero as T increases from zero to the transition temperature T c . The Cooper-pair system undergoes a first-order phase transition from the normal state to the Bose condensed state.

An asymmetric chiral metamaterial (CMM) circular polarizer based on bilayer twisted split-ring resonator structure was proposed and investigated. Both numerical simulations and experiments reveal that when a y-polarized wave is incident on this CMM propagating along backward (−z) direction, the two linear components of the transmitted wave have nearly equal amplitudes and 90°(−90°) phase difference at the resonant frequencies. This means that the right-hand circular polarization and left-hand circular polarization are realized in transmission at 6.4 and 8.1 GHz, respectively. The surface current distributions are studied to illustrate the transformation behavior for both circular polarizations. Further, the influences of the structural parameters of the circular polarizer to the transformation transmissions spectra have been investigated numerically.

Our experimental scheme is based on a barrel optical microresonator filled with a dye solution. The barrel mirror provides a confining potential, a chemical potential, and an effective mass for a photon, making the system formally equivalent to a one-dimensional gas of harmonically trapped, number-conserving, and massive bosons. Within the framework of quantum statistical mechanics, we propose an exact analytical solution to the problem of Bose-Einstein condensation in harmonically trapped, one-dimensional, and ideal photons. It is found that the photon number of vapor is characterized by an analytical function, which involves a $q$-digamma function in mathematics. The numerical calculation of the analytical solution gives many interesting results. In the thermodynamic limit, the analytical expressions of the critical temperature and the condensate fraction are derived. We find that the spectral radiance of a one-dimensional barrel cavity has a sharp peak at the frequency of the cavity cutoff when the photon number exceeds the critical value determined by a temperature.

Bose–Einstein condensation of a weakly interacting photon gas in a two-dimensional optical microcavity is investigated. The effective mass and chemical potential for a photon confined inside this optical microcavity are non-vanishing. A reservoir theory has been used to study the decay rate of a two-level atom in the microcavity, in which photons are in the Bose–Einstein condensate state. It is found that below the critical temperature T c , the atomic decay rate is a monotonically increasing function of the absolute temperature T.

We investigate the Bose-Einstein condensation of photons and photon pairs in a two-dimension optical microcavity. We find that in the paraxial approximation, the mixed gas of photons and photon pairs is formally equivalent to a two dimension system of massive bosons with non-vanishing chemical potential, which implies the existence of two possible condensate phase. We also discuss the quantum phase transition of the system and obtain the critical point analytically. Moreover, we find that the quantum phase transition of the system can be interpreted as second harmonic generation.

Within the framework of the theory of q -deformed bosons, we investigate Bose–Einstein condensation of a q -deformed boson system, which has finite particle number and is trapped in a harmonic potential trap, by using the approach of modified density of states. For such a trapped q -deformed boson system, we obtain the expressions of the effective critical temperature T c , the ground state population N 0 / N and the specific heat C . Further numerical calculation shows that Bose–Einstein condensation of such a system has some particular and interesting features which are different from those of a trapped standard boson system. We consider that this work may provide much insight into the theory of q -deformed bosons, and may also be useful for the further study on Bose–Einstein condensation of a concrete trapped q -deformed boson system.

In this paper, an Improved Nonsingular Terminal Sliding-mode (INTSM) observer is proposed to estimate the speed of the permanent magnet synchronous motor (PMSM). The Nonsingular Terminal Sliding-mode (NTSM) not only inherits the good performance to track the state error, but also has the characteristic of limited time convergence. However, the conventional NTSM control law is too complex to apply in practice. The INTSM takes the thoughts of the fast Terminal Sliding-mode and uses a new nonlinear term to replace the conventional term. As a result, the new observer owns the characteristics of global fast convergence and simple control law. At last, the proposed method proves to be effective through the theoretical analysis and simulation test.

Artificial graphene structures embedded in semiconductors could open novel routes for studies of electron interactions in low-dimensional systems. We propose a way to manipulate the transport properties of massless Dirac fermions in an artificial graphene-based tunnel junction. Velocity-modulation control of electron wave propagation in the different regions can be regarded as velocity barriers. Transmission probability of electron is affected profoundly by this velocity barrier. We find that there is no confinement for Dirac electron as the velocity ratio ξ is less than 1, but when the velocity ratio is larger than 1 the confined state appears in the continuum band. These localized Dirac electrons may lead to the decreasing of transmission probability.

We study magnetic field modulated transport properties of Dirac fermions in graphene, where Dirac fermions penetrate through a velocity barrier. We find strong wave vector filtering and resonant effect. The angular-dependent region of resonant tunneling is suppressed by tuning velocity barriers. We can also found that the confined states in this velocity barrier can be changed by the magnetic field. Various novel devices, such as wavevector filter and magnetic switches, may be constructed based on our observed phenomena.

Electricity transformer is an important, widely used electrical equipment. Current the iron beam sectional of the electricity transformer is based on experienced standards which can not achieve the best economic benefits. According to practical technology, we build a basic optimization model about multistep iron beam section. And we also give a reasonable design on the tolerance zone between the diameter of iron beam sectional circumcircle and the diameter of the winding steel-flue, as well as the arrangement about the oil path in the iron beam, which has a big realistic significance and application value. We come up with five reasonable model assumptions to simplified the problem, turning the tolerance zone design problem into the function extreme one. We adopt "Ideal assumption first, specific modification second" method on designing the oil path, considering all kinds of situations to obtain optimization. The core algorithm is dynamic programming which is much faster, much more stable than using Lingo. All the solving and analyzing on math models are based on C++ programming language.

We study theoretically shot noise and minimal conductivity of electrons by evanescent states penetrating through clean graphene nanoribbons (GNRs). With increasing of the barrier voltage, we find that the minimum conductivity will increase to 4 e 2 / π h and the maximum Fano factor will increase to 1/3. More interestingly, quantum oscillations can be tuned by the gate voltage and separated by tuning the barrier voltage

This paper develops a portable all-position welding robot for the welding of intersected pipes. The mathematical model of welding seam has been established and a complete procedure is adopted to conduct the design. The task and motion of the robot are analyzed and a mathematical description of the pose and position of the welding torch is given. Based on that, a new kind of 5 degree of freedoms welding robot has been designed with mixed method of series and parallel for satisfying welding seam of intersecting pipes. An automatic centering robot trick with 2 degree of freedoms has also been designed, which realized the control of torch position and posture separately. The welding result indicates that the anchor is surely secure and accurate and the control method can satisfy the technological requirements of welding seam of intersection.

Bose–Einstein condensates of repulsive Bose atoms in a one-dimensional harmonic trap are investigated within the framework of a mean field theory. We solve the one-dimensional nonlinear Gross–Pitaevskii (GP) equation that describes atomic Bose–Einstein condensates. As a result, we acquire a family of exact breather solutions of the GP equation. We numerically calculate the number density [Formula: see text] of atoms that is associated with these solutions. The first discovery of the calculation is that at the instant of the saddle point, the density profile exhibits a sharp peak with extremely narrow width. The second discovery of the calculation is that in the center of the trap ([Formula: see text] m), the number density is a U-shaped function of the time [Formula: see text]. The third discovery of the calculation is that the surface plot of the density [Formula: see text] likes a saddle surface. The fourth discovery of the calculation is that as the number [Formula: see text] of atoms increases, the Bose–Einstein condensate in a one-dimensional harmonic trap becomes stabler and stabler.

In this Letter, some properties of magnetopolarons in two-dimensional quantum dot are investigated by two-mode squeezed states transformation. This method considers linear functions, bilinear functions of the phonon operators and the correlation between two longitudinal optical (LO) phonon modes, which is based on the Lee–Low–Pines and Huybrechts (LLP–H) canonical transformations. So it can provide results not only for the ground state energy but also for the excited states energies, furthermore, it can be applied to the entire range of the electron–phonon coupling strength. Using two-mode squeezed states transformation, we have obtained more accurate results for the ground state energy, excited states energies and renormalized cyclotron masses for some possible transitions.

The fracture mechanisms of Hg 0.8 Cd 0.2 Te induced by pulsed TEA-CO 2 laser have been investigated theoretically and experimentally in this paper. The Hg 0.8 Cd 0.2 Te target was irradiated by a TEA-CO 2 laser with wavelength of 10.6 μm and spike width of 240 ns in an ambient atmosphere. The evident cracks can be found on the surface of the target from the scanning electron microscopy (SEM) photos, indicating that the severe breaks happened during the experiment. Theoretical analysis has also been carried out and the results show that the fracture of Hg 0.8 Cd 0.2 Te is mainly induced by thermal stresses, although there are three forces (thermal stress, evaporation wave and laser-supported detonation (LSD) wave) exerted on the target surface during the process.

We propose a two-dimensional model consisting of photons and photon pairs. In the model, the mixed gas of photons and photon pairs is formally equivalent to a two-dimensional system of massive bosons with non-vanishing chemical potential, which implies the existence of two possible condensate phases. Using the variational method, we discuss the quantum phase transition of the mixed gas and obtain the critical coupling line analytically. Moreover, we also find that the phase transition of the photon gas can be interpreted as second harmonic generation. We then discuss the entanglement between photons and photon pairs. Additionally, we also illustrate how the entanglement between photons and photon pairs can be associated with the phase transition of the system., Comment: 14 pages, 5 figures

In this paper, we study the head-on collision between two electron acoustic solitary waves (EASWs) in magnetized quantum electron–positron–ion plasma. Using the extended Poincare–Lighthill–Kuo perturbation method, we obtain the Korteweg–de Vries equations, the phase shifts and the trajectories after the head-on collision of the two EASWs. It is found that the phase shifts are significantly affected by the values of the quantum parameter H, the ion to electron number density ratio δ, the electron cyclotron to electron plasma frequency ratio α and the obliqueness θ (propagation angle).

We investigate the energy-level shift of a hydrogen atom in a two-dimensional optical microcavity, where there exists a Bose—Einstein condensation of photons. It is found that below the critical temperature Tc, the energy-level shift of the bound electron is dependent on temperature, and it is a monotonically increasing function of the absolute temperature T. Especially, at the absolute zero temperature, the energy-level shift entirely comes from the Lamb shift, and the atom can be treated approximately, that is, in vacuum.

Motivated by the realization of the Dirac point with tunable Fermi velocity in low-dimensional systems, we investigate the guided modes in graphene waveguides corresponding to the electron motion (or the hole motion) in a symmetric velocity barrier. We find that the fundamental mode always exists, but the higher-order mode may disappear. These discrete guided modes imply that there is a lowest cutoff frequency for an incident electron and that the incident electrons with different angles may have different minimum cutoff frequencies. These interesting features will be helpful for the investigation on an electronic fiber.

TI ;resent papa establishes tI photonic superginding t1oiy in polar aystals with a high non1inrity Inthe microscoic tIoiy it is shown that photons can feel an attractive efftive interaction by exthan d virtualphonoi. Such an intaction leads to tl supaguiding state, in which the photons with ooalte wave vtoiand spins are bound into pairs The photon pairs travel without stting attenuations. In the semidascaI the-. ory we find that polar crystals with a high nonlinearity are self- &foaising media with dispersion and the opti— cal fibers made from such crystals n progate temporal solitcis without dispersion. If the photons propagating in such a waveguide enter the superguicling state, the waveguide exhibits both an ultralow eirgy loss and a high transmission rate. 1. INTRODUCTION Recently son iw concepts of photons analogous to those of elerons have been propcsed Berry hasrecognized in quantum mechanics a topolojcaI phase factor aring from the adiattic transport of a systemaround a dosi &CL1L