Electrode Erosion of a High Energy Impulse Spark Gap Switch

Based on the principle of thermal conduction, three metal alloys （stainless steel, copper-tungsten and graphite） were chosen as the material of the high impulse current discharging switch. Experimental results indicate that the mass loss and surface erosion morphology of the electrode are related with the electrode material （conductivity σ, melting point Tin, density p and thermal capacity c） and the impulse transferred charge （or energy） per impulse for the same total impulse transferred charge. The experimental results indicate that the mass loss of stainless steel, copper-tungsten and graphite are 380.10 μg/C, 118.10 μg/C and 81.90 μg/C respectively under the condition of a total impulse transferred charge of 525 C and a transferred charge per impulse of 10.5 C. Under the same impulse transferred charge, the mass loss of copper-tungsten（118.10 μg/C） with the transferred charge per impulse at 10.5 C is far larger than the mass loss （38.61μg/C） at a 1.48 C transferred charge per impulse. The electrode erosion mechanism under high energy impulse arcs is analyzed briefly and it is suggested that by selecting high conductive metal or metal alloy as the electrode material of a high energy impulse spark gap switch and setting high erosion resistance material at the top of the electrode, the mass loss of the electrode can be reduced and the life of the switch prolonged.

Energy gap suppression and excess current in TI2Ba2CaCu208 intrinsic Josephson junctions

Intrinsic Josephson junctions in misaligned T12Ba2CaCu208 thin film were fabricated on LaA103 substrate. The temperature dependence of the critical current is investigated around liquid nitrogen temperature. In the current voltage characteristic, large voltage jump and lack of resistive branch are observed, which shows good consistency with the intrinsic Josephson junctions. By analyzing the large gap voltage in the curve, great suppression of the energy gap is found. Through discussing the temperature dependence of the gap voltage in liquid nitrogen temperature, it is shown that this phenomenon can be caused by the non-equilibrium quasiparticle injection. The temperature influence on the excess current also confirms the non-equilibrium effect.

Influence of a Semiconductor Gap’s Energy on the Electrical Parameters of a Parallel Vertical Junction Photocell

The present work is a theoretical study on a parallel vertical junction solar cell under a multi-spectral illumination in static regime. The density of the minority charge carriers was determined based on the diffusion equation. Photocurrent and photovoltage are deducted from such density. All these parameters are studied taking into account the influence of the gap energy (Eg).

The Gap Labelling Integrated Density of States for a Quasi Crystal Universe Is Identical to the Observed 4.5 Percent Ordinary Energy Density of the Cosmos

Condense matter methods and mathematical models used in solving problems in solid state physics are transformed to high energy quantum cosmology in order to estimate the magnitude of the missing dark energy of the universe. Looking at the problem from this novel viewpoint was rewarded by a rather unexpected result, namely that the gap labelling method of integrated density of states for three dimensional icosahedral quasicrystals is identical to the previously measured and theoretically concluded ordinary energy density of the universe, namely a mere 4.5 percent of Einstein’s energy density, i.e. E(O) = mc2/22 where E is the energy, m is the mass and c is the speed of light. Consequently we conclude that the missing dark energy density must be E(D) = 1 - E(O) = mc2(21/22) in agreement with all known cosmological measurements and observations. This result could also be interpreted as a strong evidence for the self similarity of the geometry of spacetime, which is an expression of its basic fractal nature.

Pseudo-invariant Eigen-operator for Deriving Energy-Level Gap for Jaynes-Cummings Model

We extend the concept of invariant eigen-operator to pseudo-invariant eigen-operator case through analyzing the standard Jaynes-Cummings model. We find the pseudo-invariant eigen-operator in terms of supersymmetric generators of this model, which diretly leads to the energy-level gap for Jaynes Cummings Hamiltonian.

The Energy Efficiency Gap in Maritime Transport

There is evidence that the shipping industry could achieve energy efficiency gains through the implementation of new technologies, with considerable reductions of fuel costs and emissions to air in the sector. Although the cost reducing effects of some new technologies are well established, companies appear reluctant to innovate despite the financial and societal benefits, as a result of what is referred to as the energy efficiency gap. The global emission impacts of the shipping industry, most notably of greenhouse gases, sulphur and nitrogen oxides are increasingly attracting the attention of regulators, non-governmental organisations and the media, and shipping companies are under pressure to find new ways to reduce their emission footprint. Understanding the determinants of the energy efficiency gap in shipping is then critical in improving the environmental profile of the industry. This paper presents the results of a survey among Norwegian shipping companies aimed at gaining a better understanding of the barriers to implementation of new cost saving technologies. The paper assesses the technical barriers that have traditionally been indicated as the main cause of the energy efficiency gap in shipping. The paper results indicate that next to technical factors, important barriers are constituted also by managerial practices and legal constraints.

Evaluation of Energy Band Gap, Thermal Conductivity, Phase Transition Temperature and Elastic Response of PS/CdS Semiconducting Optical Nanocomposite

Thick film of Polystyrene (PS)/CdS semiconducting optical nanocomposite has been synthesized by dispersing nanofiller particles of CdS in PS matrix. The nanostructure of the CdS particles has been ascertained through X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). Small angle x-ray scattering analysis has been performed in order to ascertain nanocomposite character of the PS/CdS sample. Scanning Electron Microscopy (SEM) analyses of these samples have been carried out to establish the surface morphology. Optical Absorption Spectroscopy is used to measure the energy band gap of PS/CdS nanocomposite by using Tauc relation whereas Transient Plane Source Technique is used for the determination of thermal conductivity of the prepared samples. The phase transition temperature and elastic response of the prepared samples have been ascertained through Dynamic Mechanical Analyzer (DMA). This study reveals that the thermal conductivity, Young’s modulus and the toughness of the material are greatly influenced by the existence of interfacial energetic interaction between dispersed CdS nanofiller particles and matrix of PS.

Evidence for Multiple Underlying Fermi Surface and Isotropic Energy Gap in the Cuprate Parent Compound Ca2CuO2Cl2

The parent compounds of the high-temperature cuprate superconductors are Mott insulators.It has been generally agreed that understanding the physics of the doped Mott insulators is essential to understanding the mechanism of high temperature superconductivity.A natural starting point is to elucidate the basic electronic structure of the parent compound.Here we report comprehensive high resolution angle-resolved photoemission measurements on Ca_2CuO_2Cl_2,a Mott insulator and a prototypical parent compound of the cuprates.Multiple underl.ying Fermi surface sheets are revealed for the first time.The high energy waterfall-like band dispersions exhibit different behaviors near the nodal and antinodal regions.Two distinct energy scales are identified：a d-wave-like low energy peak dispersion and a nearly isotropic lower Hubbard band gap.These observations provide new information of the electronic structure of the cuprate parent compound,which is important for understanding the anomalous physical properties and superconductivity mechanism of the high temperature cuprate superconductors.

Magnon energy gap in a four-layer ferromagnetic superlattice

The magnon energy band in a four-layer ferromagnetic superlattice is studied by using the linear spin-wave approach and Green＇s function technique. It is found that three modulated energy gaps exist in the magnon energy band along Kx direction perpendicular to the superlattice plane. The spin quantum numbers and the interlayer exchange couplings all affect the three energy gaps. The magnon energy gaps of the four-layer ferromagnetic superlattice are different from those of the three-layer one. For the four-layer ferromagnetic superlattice, the disappearance of the magnon energy gaps △ω12, △ω23 and △ω34 all correlates with the symmetry of this system. The zero energy gap △ω23 correlates with the symmetry of interlayer exchange couplings, while the vanishing of the magnon energy gaps △ω12 and △ω34 corresponds to a translational symmetry of x-direction in the lattice. When the parameters of the system deviate from these symmetries, the three energy gaps will increase.

Nitrogen-tailored quasiparticle energy gaps of polyynes

Polyyne,an sp~1-hybridized linear allotrope of carbon,has a tunable quasiparticle energy gap,which depends on the terminated chemical ending groups as well as the chain length.Previously,nitrogen doping was utilized to tailor the properties of different kinds of allotrope of carbon.However,how the nitrogen doping tailors the properties of the polyyne remains unexplored.Here,we applied the GW method to study the quasiparticle energy gaps of the N-doped polyynes with different lengths.When a C atom is substituted by an N atom in a polyyne,the quasiparticle energy gap varies with the substituted position in the polyyne.The modification is particularly pronounced when the second-nearest-neighboring carbon atom of a hydrogen atom is substituted.In addition,the nitrogen doping makes the Fermi level closer to the lowest unoccupied molecular orbital,resulting in an n-type semiconductor.Our results suggest another route to tailor the electronic properties of polyyne in addition to the length of polyyne and the terminated chemical ending groups.

Energy Gap for Some Hamiltonian Systems Describing Polariton Systems Obtained via Invariant Eigen-operator Method

Based on the invariant eigen-operator method （lEO） [Phys. Left. A 321 （2004） 75] we derive the exact energy gap for some Hamiltonians, which describe some polariton systems. The result shows that in some cases the IEO method, stemming from the Heisenberg approach, is more direct and convenient for deriving the energy-level gap formula than via the approach of solving the Schrodinger equation.

Tip-Pressure-Induced Incoherent Energy Gap in CaFe_2As_2

In CaFe2 As2, superconductivity can be achieved by applying a modest c-axis pressure of several kbar. Here we use scanning tunneling microscopy/spectroscopy （STM/S） to explore the STM tip pressure effect on single crystals of CaFe2 As2. When performing STM/S measurements, the tip-sample interaction can be controlled to act repulsive with reduction of the junction resistance, thus to apply a tip pressure on the sample. We find that an incoherent energy gap emerges at the Fermi level in the differential conductance spectrum when the tip pressure is increased. This energy gap is of the similar order of magnitude as the superconducting gap in the chemical doped compound Cao.4Nao.6Fe2As2 and disappears at the temperature well below that of the bulk magnetic ordering. Moreover, we also observe the rhombic distortion of the As lattice, which agrees with the orthorhombic distortion of the underlying Fe lattice. These findings suggest that the STM tip pressure can induce the local Cooper pairing in the orthorhombic phase of CaFe2As2.

Deriving Energy-Gap of Some Nonlinear Hamiltonians by Invariant Eigen-operator Method

By virtue of the invariant eigen-operator method we search for the invariant eigen-operators for someHamiltonians describing nonlinear processes in particle physics.In this way the energy-gap of the Hamiltonians can benaturally obtained.The characteristic polynomial theory has been fully employed in our derivation.

Some Implications of an Alternate Equation for the BCS Energy Gap

A set of generalized-BCS equations (GBCSEs) was recently derived from a temperature-dependent Bethe-Salpeter equation and shown to deal satisfactorily with the experimental data comprising the Tcs and the multiple gaps of a variety of high-temperature superconductors (SCs). These equations are formulated in terms of the binding energies W1(T),W2(T),… of Cooper pairs (CPs) bound via one- and more than one-phonon exchange mechanisms;they contain no direct reference to the gap/s of an SC. Applications of these equations so far were based on the observation that for elemental SCs |W01|=△0 at T = 0 inthe limit of the dimensionless BCS interaction parameter λ→0. Here △0 is the zero-temperature gap whence it follows that the binding energy of a CP bound via one-phonon exchanges at T = 0 is 2|W01|. In this note we carry out a detailed comparison between the GBCSE-based W1(T) and the BCS-based energy gap △(T) for all 0≤T≤Tc and realistic, non-vanishingly-small values of λ. Our study is based on the experimental values of Tc Debye temperature , and ?0 of several selected elements including the “bad actors” such as Pb and Hg. It is thus established that the equation for W1(T) provides a viable alternative to the BCS equation for △(T). This suggests the use of, when required, the equation for W2(T) which refers to CPs bound via two-phonon exchanges, for the larger of the two T-dependent gaps of a non-elemental SC. These considerations naturally lead one to the concept of T-dependent interaction parameters in the theory of superconductivity. It is pointed out that such a concept is needed both in the well-known approach of Suhl et al. to multi-gap superconductivity and the approach provided by the GBCSEs. Attention is drawn to diverse fields where T-dependent Hamiltonians have been fruitfully employed in the past.

Energy Gap in Saturn’s Rings

In this article, we consider, based on the super-diamagnetic model, the new problems of Saturn’s rings discovered by Cassini, such as: 1) anomalous purity of water ice;2) Saturn’s magnetic field alignment with the planet’s rotation axis;3) “ring rain” of the submicron particles;4) the deviation in the qualitative composition of the “rain” from the composition of the rings;5) “dirt” concentrated in the ring gaps;6) “plateaus” in Saturn’s C ring;7) age of the rings;8) roll-off in the spectrum of Saturn’s rings, and 9) “propellers” in Saturn’s A ring. Interpretation of Cassini’s observations of spectral roll-off in Saturn’s rings in the wavelength range from 100 micrometers to 0.5 mm is given. It was concluded that the substance of the rings could be in the superconducting state. An explanation of the Cassini spectral data is given using the hypothesis of the existence of a superconducting energy gap in the substance of rings.

Gap States of ZnO Thin Films by New Methods:Optical Spectroscopy,Optical Conductivity and Optical Dispersion Energy

The optical reflectance and transmittance spectra in the wavelength range of 300-2500 nm are used to compute the absorption coefficient of zinc oxide films annealed at different post-annealing temperatures 400, 500 and 600°C.The values of the cross point between the curves of the real and imaginary parts of the optical conductivity ɑ_1 and ɑ_1 with energy axis of films exhibit values that correspond to optical gaps and are about 3.25-3.3 eV. The maxima of peaks in plots dR/dλ and dT/dλ versus wavelength of films exhibit optical gaps at about 3.12-3.25 eV.The values of the fundamental indirect band gap obtained from the Tauc model are at about 3.14-3.2 eV. It can be seen that films annealed at 600°C have the minimum indirect optical band gap at about 3.15 eV. The films annealed at 600°C have Urbach＇s energy minimum of 1.38 eV and hence have minimum disorder. The dispersion energy d of films annealed at 500°C has the minimum value of 43 eV.

Crystal Sizes and Energy Gaps of Cerium Oxide Using Co-Precipitation Method

Co-precipitation was used to prepare cerium oxide nano-particles. The effects of aging temperature and concentration of cobalt ion on the optical property, morphology, and particle size were investigated. The cerium oxide was prepared by adding ammonia solution into a mixed solution of cerium nitrate with cobalt nitrate solutions to obtain a large amount of precipitates and then aged further. Subsequently, the precipitates were kept in an oven for calcination keeping the temperature at 400?C for lasting 24 h. The average size of cerium oxide particles was obtained from the (111) peak in the X-ray diffraction pattern using the Scherrer equation. The crystal sizes obtained were found to be in the range of 11.82 - 13.47 nm. The results showed that the particle size decreased with an increase in the Co ion concentration and decreased with an increase in temperature. The SEM pictures show that the morphology for cerium oxide is granular and/or columnar. It can be seen from UV/Vis absorption spectrum that the maximum absorption peaks were in the range of 334 - 390 nm, depending on the operating conditions. The corresponding energy gaps were observed in the range of 3.18 - 3.71 eV. Subsequently, the Brus equation for the energy gap was discussed. Finally, particle size was correlated with the aging temperature and Co ion concentration.

Critical Behavior of the Energy Gap and Its Relation with the Berry Phase Close to the Excited State Quantum Phase Transition in the Lipkin Model

In our previous work [Phys. Rev. A 85 （2012） 044102], we studied the Berry phase of the ground state and exited states in the Lipkin model. In this work, using the Hellmann-Feynman theorem, we derive the relation between the energy gap and the Berry phase closed to the excited state quantum phase transition （ESQPT） in the Lipkin model. It is found that the energy gap is approximately linearly dependent on the Berry phase being closed to the ESQPT for large N. As a result, the critical behavior of the energy gap is similar to that of the Berry phase. In addition, we also perform a semiclassical qualitative analysis about the critical behavior of the energy gap.

GAP/PET/RDX基推进剂的动态冲击及点火响应行为

针对含不同粒度环三亚甲基三硝胺(RDX)的叠氮缩水甘油醚(GAP)推进剂和聚对苯二甲酸乙二醇酯(PET)推进剂,利用分离式霍普金森压杆装置开展高应变率(1000~6000s^(-1))动态冲击实验,同时结合高速摄影和数字全息光学测量技术,采用3台高速摄像机同步观测推进剂在撞击条件下损伤演化、点火响应和能量增长过程。结果表明,GAP基推进剂在高应变率压缩下的强度极限较PET基推进剂最大提升了一倍,弹性模量在不同应变率下均提升了一倍以上;中等粒度RDX较粗粒度RDX推进剂的强度极限最大提升了80%,弹性模量最大提升了148%;此外,GAP基推进剂较PET基推进剂、粗粒度较中粒度推进剂在高应变率压缩条件下更易点火,但中粒度推进剂的燃烧反应较粗粒度更加剧烈和完全。

Energy gap suppression and excess current in Tl_2Ba_2CaCu_2O_8 intrinsic Josephson junctions

Intrinsic Josephson junctions in misaligned Tl2Ba2CaCu2O8 thin film were fabricated on LaAlO3 substrate. The temperature dependence of the critical current is investigated around liquid nitrogen temperature. In the current voltage characteristic, large voltage jump and lack of resistive branch are observed, which shows good consistency with the intrinsic Josephson junctions. By analyzing the large gap voltage in the curve, great suppression of the energy gap is found. Through discussing the temperature dependence of the gap voltage in liquid nitrogen temperature, it is shown that this phenomenon can be caused by the non-equilibrium quasiparticle injection. The temperature influence on the excess current also confirms the non-equilibrium effect.