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The Back-n white neutron source at the China Spallation Neutron Source (CSNS) provides neutrons in the continuous energy region from 0.5 eV to 200 MeV. A spectrometer named Light charged Particle Detector Array (LPDA) is designed for the study of (n, lcp) reactions at Back-n. The main detector of the LPDA spectrometer, a 16-unit ΔE-ΔE-E telescope array, is composed of two arrays of 8-unit ΔE-ΔE-E telescope. Each telescope unit consists of a Low-Pressure Multi-Wire Proportional Chamber (LPMWPC), a Si-PIN detector, and a CsI(Tl) scintillator detector. In 2021, a neutron-proton (n-p) scattering reaction cross-section measurement experiment was accomplished as the first experiment of the telescope array. Protons can be clearly identified in the ΔE-E spectrum (LPMWPC + Si-PIN) and the ΔE-E spectrum (Si-PIN + CsI(Tl)). Cross sections of the n-p scattering reaction in the neutron energy range of several MeV are extracted. The ΔE-E method also provides new measurement opportunities for many-body neutron induced light charged-particle emission reactions.

The study of constitutive model of composite solid propellant is an important basis for analyzing the structural integrity of propellant grains of the solid rocket motor. From the view of microscopic, composite solid propellant is composed of a large number of solid particles with various sizes embedded in the matrix. In this paper, based on the distribution of solid particles with different sizes and the failure strength of the particle-matrix interfaces, the damage evolution was assumed to obey the Weibull distribution function and power law distribution function, and the two statistical damage constitutive models were first established. Then, the model parameters were identified and validated through the uniaxial tensile tests data of HTPB propellant. Finally, the prediction abilities of the developed two models were compared. The results show that both of the two statistical damage models can describe the stress-strain curves of HTPB propellant well.

The capture cross sections of the 169Tm reaction were measured at the back streaming white neutron beam line (Back-n) of the China Spallation Neutron Source (CSNS) using four C6D6 liquid scintillation detectors. The background subtraction, normalization, and correction were carefully considered in the data analysis to obtain accurate cross sections. For the resonance at 3.9 eV, the R-matrix code SAMMY was used to determine the resonance parameters with the internal normalization method. The average capture cross sections of 169Tm for energy between 30 and 300 keV were extracted relative to the 197Au reaction. The measured cross sections of the 169Tm reaction were reported in logarithmically equidistant energy bins with 20 bins per energy decade with a total uncertainty of 5.4% – 7.0% in this study and described in terms of average resonance parameters using a Hauser-Feshbach calculation with fluctuations. The point-wise cross sections and the average resonance parameters showed fair agreement with the evaluated values of the ENDF/B-VIII.0 library in the energy region studied.

Algorithmic composition is also called automated composition. It is an attempt to use a specific form of process. Composers make full use of computers to carry out music creation and reduce their access. In this paper, based on the standard support vector machine (SVM) learning neural network, the least square support vector machine (LS-SVM) is combined with the recurrent neural network, and a new least square support vector machine learning neural network is proposed. The article realizes the efficient end-to-end multi-dimensional sound wave time series generation model Music-coder, through which the music style music of the famous singer Jay Chou is generated, and the quantified similarity with the real Jay Chou music data set reaches a maximum of 97.73%. The project in this paper shows that intelligent algorithm as a composition tool for music generation and creation is an effective music production program and will bring new development to music production.

The Back-n white neutron source (known as Back-n) is based on back-streaming neutrons from the spallation target at the China Spallation Neutron Source (CSNS). With its excellent beam properties, e.g., a neutron flux of approximately 1.8×107 n/cm2/s at 55 m from the spallation target, energy range spanning from 0.5 eV to 200 MeV, and time-of-flight resolution of a few per thousand, along with the equipped physical spectrometers, Back-n is considered to be among the best facilities in the world for carrying out nuclear data measurements. Since its completion and commencement of operation in May 2018, five types of cross-section measurements concerning neutron capture cross-sections, fission cross-sections, total cross-sections, light charged particle emissions, in-beam gamma spectra, and more than forty nuclides have been measured. This article presents an overview of the experimental setup and result analysis on the neutron-induced cross-section measurements and gamma spectroscopy at Back-n in the initial years.

The angle-differential cross sections of neutron-induced deuteron production from carbon were measured at six neutron energies from 25 to 52 MeV relative to those of n-p elastic scattering at the China Spallation Neutron Source (CSNS) Back-n white neutron source. By employing the Δ E-E telescopes of the Light-charged Particle Detector Array (LPDA) system at 15.1° to 55.0° in the laboratory system, ratios of the angle-differential cross sections of the 12C(n, xd) reactions to those of the n-p scattering were measured, and then, the angle-differential cross sections of the 12C(n, xd) reactions were obtained using the angle-differential cross sections of the n-p elastic scattering from the JENDL-4.0/HE-2015 library as the standard. The obtained results are compared with data from previous measurements, all of which are based on mono-energic neutrons, the evaluated data from the JENDL-4.0/ HE-2015 library and the ENDF-B/VIII.0 library, and those from theoretical calculations based on INCA code and Talys-1.9 code. Being the first white-neutron-source-based systematic measurement of the angle-differential cross sections of neutron-induced deuteron production reactions on carbon in several tens of MeV, the present work can provide a reference to the data library considering the lack of experimental data.

The soft sandstone is taken as samples, and the RLW-2000M triaxial rheological testing machine is used as the main equipment to test the axial stress-strain, the axial rheological deformation in this paper. The axial strain is selected as damage variables, the damage degree expression is derived, and the effect of each factor on damage degree is studied. Research results show that axial deformation increases with the passage of time, and the hysteresis curve change from sparse to dense under the action of the dynamic loading. The axial deformation increase with the increase of the dynamic loading amplitude, and it increases with the decrease of frequency. The damage degree of specimen tends to be stable after mutation and increases with the increase of the dynamic loading amplitude. The research results will provide the scientific basis for us to disclose the rule of rheology-damage evolution of sandstone under the action of dynamic loading.

The influence of slag powder, cement and bentonite on the permeability coefficient of granite residual soil at different incorporation ratios was analyzed by means of seepage test with variable head. Meanwhile, the permeability coefficient was compared with that of the original granite residual soil. It is found that the effect of slag powder on reducing the permeability coefficient of granite residual soil under non-alkaline environment is limited. The effect of cement on decreasing permeability coefficient of granite residual soil is obvious. Bentonite has the best effect on reducing permeability coefficient of granite residual soil.

A two-dimensional detonation in H2–O2 system is simulated by a high-resolution code based on the fifth-order weighted essentially non-oscillatory (WENO) scheme in the spatial discretization and the 3th-order additive Runge–Kutta schemes in the time discretization, by using a detailed chemical model. The effect of a concentration gradient on cellular detonation is investigated. The results show that with the increase of the concentration gradient, the cell instability of detonation increases and gives rise to the oscillation of average detonation velocity. After a long time, for the case of the lower gradient the detonation can be sustained, with the multi-head mode and single-head mode alternating, while for the higher gradient it propagates with a single-head mode.

In order to improve the precision of untethered magnetic manipulation polishing of material workpieces, this paper proposes a new surface path-planning method for free-form surfaces based on the refinement of the conventional polishing path method and determination of its relevant parameters. The results obtained and proposed optimization rules also make it possible minimize the regular scratches and uneven polishing caused by the path itself in a conventional raster-shaped path and reduce the spatial error.

The 6Li(n, t)4He reaction was measured as the first experiment involving neutron-induced charged particle emission reactions at the CSNS (China Spallation Neutron Source) Back-n white neutron source. The differential cross-sections of the 6Li(n,t)4He reaction at 15 detection angles ranging from 19.2° to 160.8° are obtained from 1.0 eV to 3.0 MeV at 80 neutron energy points; for 50 energy points below 0.1 MeV they are reported for the first time. The results indicate that the anisotropy of the emitted tritium is noticeable above E n = 100 eV. The angle-integrated cross-sections are also obtained. The present differential cross-sections agree in general with the previous evaluations, but there are some differences in the details. More importantly, the present results indicate that the cross-sections of the 6Li(n, t)4He reaction might be overestimated by most evaluations in the 0.5 − 3.0 MeV region, although they are recommended as standards below 1.0 MeV.

In this study, we focused on the longitudinal magnetic field effect in critical current densities and investigated the enhancement of the electrical conduction properties in a commercial Bi-2223 superconducting tape. Since the samples used in this study were polycrystalline and tape-shaped, the longitudinal magnetic field effect was expected to differ from that in single crystals or conventional superconducting alloys. Therefore, the critical current characteristics at magnetic fields of up to 5 T as well as at various angles between the magnetic field and current were measured in detail.

We theoretically design a versatile compact optical system comprising large-scale organic light-emitting diode (OLED) light sources and a freeform Fresnel lens to generate a highly collimated incoherent planar light source (HCIPLS) with uniform irradiance distribution. The structural parameters related to the output collimated light beam are discussed in detail. The simulated optimal full width at half maximum (FWHM) of the angular intensity distribution of the proposed structure is as high as 6.9° at both vertical and horizontal viewing angles. Moreover, the calculated normalized luminance enhancement factor reaches 25.4 in the range of normal viewing angles.

In this study, we prepared fibre metal laminates (FMLs) consisting of high-modulus carbon fibre-reinforced polymer (CFRP) prepregs and thin AZ31 alloy sheets by using hot-pressing technology. Tensile and low-velocity impact tests were performed to evaluate the mechanical properties and fracture behaviour of the magnesium alloy-based FMLs (Mg-FMLs) and to investigate the differences in the fracture behaviour between the Mg-FMLs and traditional Mg-FMLs. Results show that the Mg-FMLs exhibit higher specific tensile strength and specific tensile modulus than traditional Mg-FMLs and that the tensile behaviour of the Mg-FMLs is mainly governed by the CFRP because of the combination of high interlaminar shear properties and thin magnesium alloy layers. The Mg-FMLs exhibit excellent bending stiffness. Hence, no significant difference between the residual displacement d r and indentation depth d i , and the permanent deformation is mainly limited to a small zone surrounding the impact location after the impact tests.

We show that dark and bright vortex solitons can exist in three-state electromagnetically induced transparent media under some appropriate conditions. We also analyse the stability of the dark and bright vortex solitons. This work may provide other research opportunities in nonlinear optical experiments and may result in a substantial impact on technology.

The electron paramagnetic resonance (EPR) parameters (g factors g(parallel to), g(perpendicular to) and zero-field splitting D) of the approximately tetragonal defect centre Fe-Zn(+) -X in cubic ZnS crystal are calculated from high-order perturbation formulae based on the two spin-orbit coupling parameter model for the EPR parameters of the 3d(7) ion in tetragonal symmetry. From the calculations, we suggest that the associated defect X (which is at the interstitial site on a (100) axis, but its origin and nature remain unknown) in this centre has a negatively charged state (i.e. an anion). The slightly monoclinic distortion of this defect centre is attributed to a further anion S2- vacancy Vs(2-) in the vicinity of defect X owing to charge compensation. The defect model is discussed.

In terms of Darboux transformation, we have exactly solved the higher-order nonlinear Schrodinger equation that describes the propagation of ultrashort optical pulses in optical fibers. We discuss the modulation instability (MI) process in detail and find that the higher-order term has no effect on the MI condition. Under different conditions, we obtain Kuznetsov–Ma soliton and Akhmediev breather solutions of higher-order nonlinear Schrodinger equation. The former describes the propagation of a bright pulse on a continuous wave background in the presence of higher-order effects and the soliton's peak position is shifted owing to the presence of a nonvanishing background, while the latter implies the modulation instability process that can be used in practice to produce a train of ultrashort optical soliton pulses.

Left-handedness with three zero-absorption windows is achieved in a triple-quantum-dot system. With the typical parameters of a GaAs/AlGaAs heterostructure, the simultaneous negative relative electric permittivity and magnetic permeability are obtained by the adjustable incoherent pumping field and two inter-dot tunnelings. Furthermore, three zero-absorption windows in the left-handedness frequency bands are observed. The left-handedness with zero-absorption in the solid state heterostructure may solve the challenges not only in the left-handed materials achieved by the photonic resonant scheme but also in the application of negative refractive materials with a large amount of absorption.

Two-dimensional (2D) atom localization via the spontaneously generated coherence (SGC) and detunings associated with the probe and standing-wave driving fields in a three-level V-type atomic system are investigated. In the gain process, two equal and tunable peak maxima of position distribution in the x—y plane via the detunings are observed. However, one decreasing and the other increasing peak maxima in the absorption process via the SGC are achieved in the quadrants I and III of the x—y plane. A better resolution and more novelty for the 2D atom localization in our scheme are obtained.

Water-dispersible two-dimensional (2D) assemblies of Au@Ag core-shell nanoparticles are obtained through a highly selective electroless silver deposition on pre-assembled gold nanoparticles on bovine serum albumin (BSA)-coated graphene oxide (BSA-GO). While neither BSA-GO nor AuNP-decorated BSA-GO shows any antibacterial ability, the silver-coated GO@Au nanosheets (namely GO@Au@Ag) exhibit an enhanced antibacterial activity against Gram-negative Escherichia coli (E. coli) bacteria, superior to unassembled Au@Ag nanoparticles and even ionic Ag. Such an improvement may be attributed to the increased local concentration of silver nanoparticles around a bacterium and a polyvalent interaction with the bacterial surface. In addition, the colloidal stability of this novel nano-antimicrobial against the formation of random nanoparticle aggregates guarantees a minimized activity loss of the Au@Ag nanoparticles. The antibacterial efficacy of GO@Au@Ag is less sensitive to the existence of Cl⁻, in comparison with silver ions, providing another advantage for wound dressing applications. Our research unambiguously reveals a strong and very specific interaction between the GO@Au@Ag nanoassembly and E. coli, which could be an important clue toward a rational design, synthesis and assembly of innovative and highly active antibacterial nanomaterials.

In this paper, we have investigated three external fields interacting with the four-level atomic system described by the density-matrix approach. The atomic system exhibits left-handedness with zero absorption and large negative refractive index. Varying the parameters of the three external fields, the properties of zero absorption and large negative refractive index from the atomic system remain unvarying. Our scheme proposes an approach to obtain a negative refractive medium with zero absorption. The zero absorption property of the atomic system may be used to amplify the evanescent waves that have been lost in the imaging by traditional lenses, and a slab fabricated by the left-handed atomic system may be an ideal candidate for designing perfect lenses.

The high order perturbation formulas for spin-Hamiltonian (SH) parameters ( g factors g parallel to, g perpendicular to and zero-field splitting D) for 3d(3) ions in tetragonal symmetry are established using a cluster approach. In these formulas, not only is the contribution to the SH parameters from the crystal-field (CF) mechanism included, but so also is that from the charge-transfer (CT) mechanism ( which is neglected in the widely used CF theory). From these formulas, the g shifts Delta g parallel to (= g parallel to - g(e), where g(e) approximate to 2.0023, the value for the free electron),Delta g(perpendicular to). (= g perpendicular to- g(e)) and the zero-field splitting D for the tetragonal Fe5+ center in SrTiO3 crystal are calculated. The results ( in particular, the positive g shifts, which cannot be explained on the basis of the CF mechanism) are in good agreement with the observed values. The calculation results show that (i) the sign of Delta g(i)(CT) ( i = parallel to or perpendicular to) due to the CT mechanism is opposite to that of Delta g(i)(CF) due to the CF mechanism, but the sign of D-CT is the same as that of D-CF and (ii) the ratio | Q(CT)/ Q(CF)| (which represents the relative importance of the CT mechanism) takes values of about 143%, 143% and 114% for Q = Delta g parallel to, Delta g perpendicular to and D, respectively. This suggests that the positive g shifts are due mainly to the contribution of the CT mechanism; therefore for the high valence state 3d(n) ions in crystals, the contribution to SH parameters from the CT mechanism should be taken into account. The defect structure of the Fe5+ center in SrTiO3 crystal is also obtained from the calculations. The result is consistent with the expectations based on charge compensation and electrostatic interaction.