Gauge dependence of chiral condensate and fermion mass by an unquenched model

Based on three-dimensional quantum electrodynamics theory,a set of truncated Dyson-Schwinger（D-S） equations are solved to study photon and fermion propagators with the effect of vacuum polarization.Numerical studies show that condensation and the value of fermion mass depends heavily on how the D-S equations are truncated.By solving a set of coupled D-S equations,it is also found that the fermion propagator shows a clear dependence on the order parameter.The truncated D-S equations under unquenched approximation are used to study the mass-function and chiral condensation of the fermions.The results under the unquenched approximation are clearly different from the ones under quenched approximation.With the increase in the order parameter,the fermion condensation in the unquenched approximation decreases when 0≤ξ5,while it increases when ξ5.However,nothing like this is observed in the quenched approximation,which indicates that there may be flaws in the quenched approximations.

Eigenstate Distribution Fluctuation of a Quenched Disordered Bose–Hubbard System in Thermal-to-Localized Transitions

We study the thermalization of a quenched disordered Bose–Hubbard system. By considering the eigenstate distribution fluctuation, we show that the thermal to many-body localized transition is always connected to a minimum of this distribution fluctuation. We also observe a Mott-localized regime, where the system fails to thermalize due to the strong on-site repulsion. Lastly, we show how to detect this eigenstate distribution fluctuation in a cold atom system, which is equivalent to measure the Loschmidt echo of the system. Our work suggests a way to measure the thermal-to-localized transitions in experiments, especially for a large system.

Study on the resistance spot welding technology of 22MnMoB hot stamping quenched steel

In this paper, the spot welding technology of a new kind of 22MnMoB hot stamping quenched steel sheet was systematically studied by power frequency spot welder. Through a series of technology and test experiments, we have obtained the optimal spot welding technological parameter condition. According to the results, the relations among spot welding technological parameter, welding nugget, mechanical property and fracture mode were discussed. The effects of all the welding parameters such as welding current, welding time and electrode force on the quality of joint can be boiled down to one thing--the diameter of welding nugget. The experimental results showed that welding nugget diameter determines the mechanical property of spot welding joint and the relation between welding nugget diameter and the mechanical property of joint presents a kind of linear mathematic representation. There are two typical fracture models of 22MnMoB hot stamping quenched steel sheet, i.e., interracial fracture and nugget pullout. Other than mild steel or normal high strength steel, in the shearing tensile test, hot stamping quenched steel has a great tendency to fail in interfacial mode due to the effects of high strength matrix structure, welding soft zone and the porosity level of fusion zone.

Crystallization behavior of Zr_(52) Cu_(18) Ni_(15) Al_(10) Ti_5 bulk glass with quenched-in crystals

Zr 52 Cu 18 Ni 15 Al 10 Ti 5 bulk glass samples with a diameter of 8 mm prepared by copper mold with water cooling have a mixing structure of amorphous phase and quenched in crystals. By isothermal annealing at different temperatures, the crystallization process of the glass alloy is shown to be a multi staged crystallization reaction as follows: Am+quenched in crystals→Am′+cellular phase+(Zr, Ti) Al→Am′+cellular phase+(Zr, Ti) Al+(Zr, Ti) 2(Cu, Ni). Morphology of the quenched in crystals changes from dot or dendritic phase in the as cast bulk glass to cellular phase at different annealing states. The residual region surrounded by the cellular phase has a mixing structure of nano scale phase and amorphous phase.

Oil quenched malleable iron,the strength of an old material in a “green cast” development and a new future

Malleable iron lost the interest and the development stopped in the turbulent seventies of tremendous developments of new technologies. The personal computer, emission spectrometer, thermal analysis, cold-box core system and automatic vertical moulding were introduced into the foundry industry. Experience shows that these new technologies do not always match up with malleable iron. Solidifciation and mould filling simulation programs are not always capable to handle a low carbon equivalent iron like malleable iron. Recent developments show however by using these new technologies and combined with practical experience, it is possible to increase the casting yield of malleable iron to the same level as ductile iron. The mechanical properties, especially the yield strength of malleable iron according to the standard are equivalent to those of ductile iron, however the yield strength of oil quenched malleable iron is signifciantly higher than that of ductile iron. An extensive investigation is made between ductile iron, air quenched and oil quenched malleable irons based on the properties of more than 350 test bars produced under the same conditions. The results are compared with the existing international standards and discussed. Other properties like fatigue strength and response to surface treatments as induction hardening are also discussed. The costs of malleable iron are reviewed and compared with other ferro alloys. These recent developments in increasing the casting yield, the understanding of the strength, makes malleable iron competitive with ductile iron and cheaper than the first grade of ausferritic ductile iron, or steel qualities. It is possible to design lighter and save weight which is essential in the automotive industry. An example of "green cast" development for typical applications, used in automotive transmissions and engines are shown.

STRUCTURAL REARRANGEMENT AND PROPERTIES OF QUENCHED TITANATE GLASSES REHEATED AT T_g

The structural rearrangement of quenched titanate glasses reheated at T-g was investigated by ESR and IR spectroscopies. Front the ESR observations it is suggested that the structure was readjusted and became more compact after the heat-treatment. A removal of residual vacancies is related to the diffusion of oxygen ions. The combination of more oxygen with titanium ions to form titanium-oxygen polyhedra and the transformation of boron-oxygen groups are confirmed front IR spectra. Some physical properties are improved after heating.

Quenched Fe moment in the collapsed tetragonal phase of Ca_(1-x)Pr_x Fe_2As_2

We report 7SAs NMR studies on single crystals of rare-earth doped iron pnictide superconductor Ca1-xPrxFe2As2. In both cases of x = 0.075, 0.15, a large increase of Vq upon cooling is consistent with the tetragonal-collapsed tetragonal structure transition. A sharp drop of the Knight shift is also seen just below the structure transition, which suggests the quenching of Fe local magnetism, and therefore offers important understanding of the collapsed tetragonal phase. At even low temperatures, the 1/75 T1 is enhanced and forms a peak at T ≈ 25 K, which may be caused by the magnetic ordering of the Pr3＋ moments or soin dynamics of mobile domain walls.

Dynamics of Non—interacting System with Long—Range Correlated Quenched Impurities

The theoretic renormalization group approach is applied to the study of the critical behavior of non-interacting system with long-range correlated quenched impurities, which has a power-like correlations . To two-loop order, the asymptotic scaling laws and the critical exponents are studied in the frame of a double expansion with ρ of order . In , it is argued that the initial slip exponent θ = 0 together with the dynamic exponent is exact in this kind of random system.

Structural Characteristics of Rapidly Quenched Al-Si Alloys

The structure of rapldly quenched Al-Si alloys (1 and 4 wt-%Si) was systematically studied by optical and transmission electron microscopy (TEM ) as welI as X-ray djffractjon (XRD). ExperimentaIresults show that rapid solidification refines the grain size. extends the solid solubility of Si in Al and Introduces a high density ot defects which exist in the forms of vacancies, dislocations and dislocation loops. etc.. The decomposition process of the alloys was fol lowed by using differential scanning calorimeter (DSC) and the activation energy for precipitation of Si was obtained through Kissinger analysis. The precipitation behaviour of Supersaturated Si in both samples was further examined by TEM. It was found that Si mainly precipitated inside the grains in Al-1 wt-%Si alloy. while in Al-4 wt-%Si alloy. nearly all the Si precipitates distributed along the grain boundaries. This may be due to the structure difference between the alloys in as-quenched state

THE STRUCTURE AND PERFORMANCES OF THE LARGE DIMEMENSION STEEL BALL MADEOF 45 STEEL QUENCHED AFTER FORGING

The structure and performances of the large dimension steel ball made of 45 steel quenched after forging have been researched. The experiments indicate that the optimum results can be obtained under proper processes.

Characterizations of Skeletal Iron Catalysts Prepared from Rapidly and Naturally Quenched Fe-Al Alloys

Surface morphology, physical-chemical properties of skeletal iron catalysts prepared by leaching of the rapidly quenched(RQ) and naturally quenched(NQ) Fe-Al alloys with an aqueous solution of NaOH were characterized by using a series of techniques including XRD, BET, XPS, SEM, H_2 and CO-TPD. It was found that the RQ skeletal iron catalyst exhibits a smaller particle size, larger specific surface area and pore volume than the NQ one. The H_2 and CO-TPD experiments showed that the RQ skeletal iron exhibits stronger affinity for H_2 and milder affinity for CO compared with the NQ one. But the NQ skeletal catalyst shows a better thermal stability than the RQ catalyst.

带随机移民分枝布朗运动在quenched概率下的中心极限定理（英文）

本文考虑当空间维数大于等于4时,带随机移民分枝布朗运动在quenched概率下的中心极限定理.与在annealed概率下的结果类似,极限是高斯随机测度;但当空间维数等于4时,高斯随机测度的协方差不同于annealed概率下的结果.

Rotating arc horizontal narrow gap welding of high strength quenched and tempered steel

Rotating arc borizontal narrow gap welding of quenched ＆ tempered （Q＆T） steel was innovatively performed for solving the bottleneck that the molten pool sagged due to the gravity. The shapely multilayer single pass horizontal joint could be obtairzed by using the rotating are welding process. The cold crack was not observed in the joint without controlling the heat input and selecting the consumables intentionally. Microstructure of the joint could be divided into three zones： base metal zone （BMZ） , heat-affected zone （ HAZ） and weld zone （WZ）. Because of the characteristic of the rotating arc horizontal welding process, the defects in the joints were slag inclztsion formed at the interlayer of lower side wall. Tbe tensile strength and hardness of HAZ and WZ were larger than those of BMZ. The impact toughness in WZ, HAZ and BM at 0 % is equal to 11.5, 212 and 236 J, respectively.

A new nonlinear photoconductive terahertz radiation source based on photon-activated charge domain quenched mode

We present a high-performance terahertz(THz)radiation source based on the photon-activated charge domain(PACD)quenched mode of GaAs photoconductive antennas(GaAs PCA).The THz radiation characteristics of the GaAs PCA under different operating modes are studied.Compared with the linear mode,the intensity of THz wave radiated by the GaAs PCA can be greatly enhanced due to the avalanche multiplication effect of carriers in the PACD quenched mode.The results show that when the carrier multiplication ratio is 16.92,the peak-to-peak value of THz field radiated in the PACD quenched mode increases by as much as about 4.19 times compared to the maximum values in the linear mode.

Discrimination Voltage and Overdrive Bias Dependent Performance Evaluation of Passively Quenched SiC Single-Photon-Counting Avalanche Photodiodes

In many critical civil and emerging military applications, low-level UV detection, sometimes at single photon level, is highly desired. In this work, a mesa-type 4H-SiC UV avalanche photodiode （APD） is designed and fabricated, which exhibits low leakage current and high avalanche gain. When studied by using a passive quenching circuit, the APD exhibits self-quenching characteristics due to its high differential resistance in the avalanche region. The single photon detection efficiency and dark count rate of the APD are evaluated as functions of discrimination voltage and over-drive voltage. The optimized operation conditions of the single photon counting APD are discussed.

Calculation of the Hardness Space Distribution in the As Quenched Condition of a Medium Hardening Tool Steel

The calculation of the hardness profile is a powerful tool for the selection of the right steel for a given purpose. Computer programs INC-PHATRAN and INDUCTER-B were formerly developed by the authors for the calculation of hardness profiles after heat treatment processes of low alloy and carbon steels. The first one simulates quenching as well as through hardening operations, and the second one models electromagnetic induction heat treatments processes. These codes make use of the SAE Standard 3406 in order to obtain the hardness profile, with enhanced regression coefficients recently obtained by the authors. The present work broadens the field of application of this method, allowing to apply it for low hardenability tool steels such as the ASTM O1 Tool Steel. The method used for the calculation of the hardness profile is here summarized, and an example of application is described, which shows good correspondence between the calculated and measured values.

UNUSUAL SOLIDIFICATION MICROSTRUCTURE OF Fe_(70)Cr_(18)Mo_2Si_1B_9 SINGLE-ROLL QUENCHED RIBBON

The solidification microstructure of Fe_(70)Cr_(18)Mo_2Si_1B_9 single-roll quenched ribbons with dif- ferent rotating speed of roller and under different atmosphere conditions was investigated. Apart from usual crystallization by homogeneous and heterogeneous nucleation,it was found that α-iron cohnnnar grains with strong preferred orientation formed beneath free surface and that spheres of α-iron single coastal with a size of several μm up to 20μm,which have rarely been reported,appeared inside the ribbons.There was experirnental evidence suggesting that clusters of metal atoms formed from fluctuation in early undercooled liquid might play a role as pre-existed nuclei and,in fact,control the formation of amorphous for this alloy.

Giant magnetoimpedance effect in as quenched Fe_(89-x)Zr_7B_4Cu_x(x=1.0-2.5) ribbons

The giant magnetoimpedance(GMI)effect in as-quenchedFe_89-xZr_7B_4Cu_x(x=1.0-2.5)ribbons is reported. The as-quenchedFe_89-xZr_7B_4Cu_x(x=1.0-2.5)ribbons were prepared by the vacuummelt-spun processes with the quenching speed of 37 m/s. The magne-Toimpedance measurement were performance at room temperature, wherethe current flow through the length of the ribbons in the directionParallel to the dc fields. results show that values Z(impedance),R(resistance)for both H = 0 A/m and H = 5 127 A/m Increases withincreasing ac frequency. This can be explained by the skin effectmechanism.

Effect of induction heating and tempering on properties and microstructures of quenched and tempered pipes

In this study,a C-Mn quenched steel tube was quickly tempered by induction heating,and the influence of the tempering temperature on its performance was studied and compared with that by traditional tempering. The results show that the yield strength of both is quite strong with regular changes in the tempering temperature,but that the tensile strength of the tube tempered by induction heating is higher than that tempered by traditional tempering by about 25 MPa,and the elongation after induction tempering is significantly higher than that after traditional tempering. The differences in the microstructures of tubes after induction and traditional tempering were compared by metallographic microscope,scanning electron microscopy,and transmission electron microscopy.Theoretical analysis was also performed. Compared with traditional tempering,a fine dispersion of precipitated carbides occurs after induction tempering,which is the main reason for the performance differences.