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The increase of neutron flux in pulsed spallation neutron facilities imposes demands on the neutron detector for beam monitoring, including excellent neutron/gamma discrimination, wide dynamic neutron-flux measurement range, wavelength resolution, and long-term stability. In this paper, we developed a ceramic GEM-based (gas electron multiplier) neutron detector with an active area of 100 mm × 100 mm. It adopted a thinner conversion material and the stopping layer to lower the detection efficiency so as to extend the dynamic measurement range of the detector. The detection efficiency of this detector was investigated by the Monte Carlo (MC) tool FLUKA, showing that the low efficiency around 0.01% for 1 Åneutrons was reached by using a 0.1 μm natB4C converter appended with an aluminum film of 2 μm thickness. Its validation of the wavelength spectra measurement was verified by comparisons with that made with an LND monitor, and it could work at the condition of 7.1 × 109 n/s for 2.5 Åneutrons. In addition, it was demonstrated that this detector was able to measure the beam profile with a position resolution of better than 2.1 ± 0.1 mm. The results of simulations and experiments show that this ceramic-GEM neutron detector can meet the requirements of the direct measurement of high-flux beam, and it will be a new neutron detector for the beam monitoring at the China spallation neutron source (CSNS).

Based on the BL09 terminal of China Spallation Neutron Source (CSNS), single event upset (SEU) cross sections of 14 nm fin field-effect transistor (FinFET) and 65 nm quad data rate (QDR) static random-access memories (SRAMs) are obtained under different incident directions of neutrons: front, back and side. It is found that, for both technology nodes, the “worst direction” corresponds to the case that neutrons traverse package and metallization before reaching the sensitive volume. The SEU cross section under the worst direction is 1.7–4.7 times higher than those under other incident directions. While for multiple-cell upset (MCU) sensitivity, side incidence is the worst direction, with the highest MCU ratio. The largest MCU for the 14 nm FinFET SRAM involves 8 bits. Monte–Carlo simulations are further performed to reveal the characteristics of neutron induced secondary ions and understand the inner mechanisms.

The first wall of the helium-cooled ceramic breeder test blanket module (TBM) will be subjected to charge exchange neutral from the mixed deuterium (D) and tritium (T) deuterium–tritium (D–T) mixture plasma irradiation. To understand the isotope effects on mixed plasma-driven permeation (PDP) through the TBM wall, which is typically made by reduced activation martensitic/ferritic steel (RAFM), mixed D and protium (H) PDP experiments for a Chinese RAFM CLF-1 have been performed. Permeation fluxes of H and D through ∼mm thick CLF-1 have been recorded at various sample temperatures and particle incident energies. The co-permeation of H and D is found to be diffusion-limited in the bulk and obeys classical mass effects of diffusion species. The H/D ratio of the permeation fluxes is found to be stable when changing sample temperature and is insensitive to ion incident energy. In addition, the mixed H can provide more channels for D recombination to reduce the D permeation.

The photon Doppler velocimetry (PDV) spectrum is investigated in an attempt to reveal the particle parameters of ejecta from shock-loaded samples in a vacuum. A GPU-accelerated Monte-Carlo algorithm, which considers the multiple-scattering effects of light, is applied to reconstruct the light field of the ejecta and simulate the corresponding PDV spectrum. The influence of the velocity profile, total area mass, and particle size of the ejecta on the simulated spectra is discussed qualitatively. To facilitate a quantitative discussion, a novel theoretical optical model is proposed in which the single-scattering assumption is applied. With this model, the relationships between the particle parameters of ejecta and the peak information of the PDV spectrum are derived, enabling direct extraction of the particle parameters from the PDV spectrum. The values of the ejecta parameters estimated from the experimental spectrum are in good agreement with those measured by a piezoelectric probe., 12 pages, 18figures

In this paper, based on the specific analysis of a temporal ghost imaging (TGI) algorithm, image coding transmission is realized by combining the compression characteristics of a Fourier transform, the convenient control and management function of ascending coding (AC) and the precise transmission function of TGI. AC, as a kind of sorting coding, has the characteristics of fast speed, high precision and wide application range. This paper analyzes noise attack, information, bit error rate (BER) and similarity, etc. Verified by simulation experiment, this algorithm can improve the compressibility of the encoded image, improve the difficulty of decoding by an attacker, reduce the BER in the process of image coding transmission, enhance the ability of anti-interference, realize accurate image coding transmission and solve the problems of low accuracy and low security of image transmission reconstruction at present.

To investigate the influence of water content on crack evolution during the fracture process of the red sandstone rock material, the damage and mechanical properties of cracked chevron notched Brazilian disc red sandstone specimens, with different water contents, were experimentally investigated. Using a P-wave velocity meter, the damage information of red sandstone specimens with different water contents, in the non-fractured region, during the pure mode I and II fracture processes, was quantitatively analyzed. The experimental results show that the damage amount of the non-fractured region, during the pure mode I and II fracture processes, increases linearly with an increase in the internal water content of the red sandstone specimens. Thus, the results from this study can provide certain theoretical basis for studying the evolution mechanism of microcracks in the fracture process of CCNBD specimens with the disparate water contents.

We set a salinity gradient, and then measure the tolerance of Sinogastromyzon szechuanensis to salinity at the initial stage and after a period of adaptation. The results show that the half lethal concentrations (LC50) of Sinogastromyzon szechuanensis at 24 h, 48 h, 72 h and 96 h are 10.50 g/L, 10.15 g/L, 9.83 g/L and 9.46 g/L respectively, and the safe concentration is 2.32 g/L. In the early stage of salinity mutation, the respiratory frequency of Sinogastromyzon szechuanensis increases with the increase of salinity. The respiratory frequency of 4 g/L group is 177±10.42 times/min, significantly higher than that of 0g/L group (PSinogastromyzon szechuanensis first decreases and then increases with the increase of salinity, and the asphyxia point of 2 g/L is the lowest, 0.81±0.02 mg/L. After 96 h adaptation, the asphyxia point of Sinogastromyzon szechuanensis in each salinity group decreases, and the asphyxia point of 0-1 g/L is the lowest, 0.60±0.06 mg/L. Conclusion: Sinogastromyzon szechuanensis has a low salinity tolerance, and its asphyxiation point is higher than that of common freshwater fish. Therefore, we suggest controlling the salinity to be 0∼2 g/L, which is helpful to enhance the hypoxia tolerance and survival rate of Sinogastromyzon szechuanensis.

The traditional smoke sensing systems have some disadvantages, including high implementation costs, difficulties in perceiving working states, low data accuracy and troubles in uniform and effective management. To address these problems, a new type of smart wireless fire monitoring system based on NB-IoT technology is innovatively designed, which realizes real-time remote monitoring and management. Compared with traditional smoke alarm systems, this system has such advantages as ultra-low power dissipation, lithium-ion battery power, no wiring, remote monitoring, low battery alarm and so forth. With great application prospect, it is worth to develop and rolled out.

Large sealed high temperature equipment usually refers to heat treatment equipment with a volume of more than 0.15m3, sealed structure and internal heating and constant temperature function. It is widely used in the fields of biochemistry, chemical pharmacy, medical and health, agricultural research, automobile and military industry. It`s a very important processing equipment. The accuracy of temperature field and vacuum sealing directly affect the quality of products. Taking the hot-pressing tank as an example, the furnace temperature tracker and wireless pressure module are used to calibrate it on the spot. According to the calibration results of temperature field distribution and temperature field performance, whether it meets the process requirements is analyzed.

The continuous improvement of system capacity and voltage level is somewhat accompanied by insulation fault as one of the main faults of GIS device. In this paper, an alternative method for identifying the GIS insulation performance based on fuzzy evidence theory is proposed by way of judging the four main features of GIS insulation level. Firstly, the fuzzy statistic test was used to obtain the normalized values of the four feature quantities of GIS insulation level. Four methods were used to calculate their respective expectations and deviations. The membership degree value was determined by the membership function, and the difference between the membership degrees was also considered. The degree of fusion was used to determine the weight of each feature quantity, so that the membership degree of the same kind of feature information fusion was obtained. Finally, the merged membership degree was transformed into the basic trust distribution function. The evidence theory then took the job to realize the pairwise fusion of the trust distribution functions between different feature quantities. The experimental results showed that this alternative way was proven to make effective judgment on the GIS insulation performance.

Short and cheap metal thermocouple is a general term for detachable short base metal thermocouple (electrode length is about 300mm-500mm) and short base metal armored couple (metal sleeve length is about 300mm-500mm). Their electrodes are short in length. Traditional measuring equipment often fails to accurately measure the indication deviation in the high temperature region (above 300 °C). Through experiments, this paper finds out the reasons of inaccurate measurement. Then, this paper designs a thermostat at the terminal, which can solve this problem. The design can effectively reduce the extended uncertainty of short-form even value deviation.

This paper explored the spatial distribution characteristics of soil erodibility K value in Gansu Province by using the calculation model of soil erodibility factor. The influencing factors of the K value was analysed by traditional statistics and geostatistics. The located monitoring data of the natural ecological station was supported by China Ecological Research Network. The following conclusions could be obtained according to this study: (1) The average soil erodibility K of Gansu Province was 0.331 t·hm2·h/(hm2·MJ·mm). (2) Gansu Province were mainly medium-high and high erosion areas. (3) The organic matter, rainfall, slope and elevation could influence K value. The rainfall and organic matter content were negatively correlated to the K value. And the slope and elevation have the law of inverted U-shaped distribution with the K value.

We modify the bilinear Backlund transformation for the discrete sine-Gordon equation and derive variety, of solutions by freely choosing parameters from the modified Backlund transformation. Dynamics of solutions and continuum limits are also discussed.

Elemental analysis of archaeological bone plays an important role in the study of the dietary habits of ancient animals. The elemental characteristic of diagenetic skeletons depends on the surrounding circumstance. The study of environmental influence on the elemental concentration of ancient bone is significant. In this paper, the diagenetic influence on archaeological skeletons is analyzed by microbeam X-ray fluorescence (μ-XRF). The results show that the enamel is an excellent barrier to the diagenesis and the element Sr in bone isn't susceptible to contamination from the buried environment.

Well-dispersed SnO2 nanorods with diameter of 4–15 nm and length of 100–200 nm are synthesised through a hydrothermal route and their potential as anode materials in lithium-ion batteries is investigated. The observed initial discharge capacity is as high as 1778 mA·h/g, much higher than the theoretical value of the bulk SnO2 (1494 mA·h/g). During the following 15 cycles, the reversible capacity decreases from 929 to 576 mA·h/g with a fading rate of 3.5% per cycle. The fading mechanism is discussed. Serious capacity fading can be avoided by reducing the cycling voltages from 0.05–3.0 to 0.4–1.2 V. At the end, SnO2 nanorods with much smaller size are synthesized and their performance as anode materials is studied. The size effect on the electrochemical properties is briefly discussed.

The shallow hydrogenic donor impurity states in square, V-shaped, and parabolic quantum wells are studied in the framework of effective-mass envelope-function theory using the plane wave basis. The first four impurity energy levels and binding energy of the ground state are more easily calculated than with the variation method. The calculation results indicate that impurity energy levels decrease with the increase of the well width and decrease quickly when the well width is small. The binding energy of the ground state increases until it reaches a maximum value, and then decreases as the well width increases. The results are meaningful and can be widely applied in the design of various optoelectronic devices.

The neutron response function for a BC501A liquid scintillator (LS) has been measured using a series of monoenergetic neutrons produced by the p-T reaction. The proton energies were chosen such as to produce neutrons in the energy range of 1 to 20 MeV. The principles of the technique of unfolding a neutron energy spectrum by using the measured neutron response function and the measured Pulse Height (PH) spectrum is briefly described. The PH spectrum of neutrons from the Pu-C source, which will be used for the calibration of the reactor antineutrino detectors for the Daya Bay neutrino experiment, was measured and analyzed to get the neutron energy spectrum. Simultaneously the neutron energy spectrum of an Am-Be source was measured and compared with other measurements as a check of the result for the Pu-C source. Finally, an error analysis and a discussion of the results are given.

Low-field electron emission is obtained from the pinaster-like MoO2 nanoarrays. The turn-on field of the pinasterlike MoO2 nanoarrays is found to be as low as 2.39 V/μm with the current density of 10μA/cm2. The enhancement factor is extracted to be 3590 from the Fowler–Nordheim plot. These excellent emission properties are attributed to the special structure of the pinaster-like MoO2 nanoarrays and confirmed by the calculation in the frame of the two-stage model. Our results show that the pinaster-like MoO2 nanoarrays are promising candidate in realizing field emission displays.

The transmiss on time and tunneling probability of an electron through a double quantum dot are studied using the transfer matrix technique. The time-dependent Schrodinger equation is applied for a Gaussian wave packet passing through the double quantum clot. The numerical calculations are carried out for a double quantum clot consisting of GaAs/InAs material. We find that the electron tunneling resonance peaks split when the electron transmits through the double quantum dot. The splitting energy increases as the distance between the two quantum dots decreases. The transmission time can be elicited from the temporal evolution of the Gaussian wave packet in the double quantum dot. The transmission time increases quickly as the thickness of tire barrier increases. The lifetime of the resonance state is calculated tram the temporal evolution of the Gaussian-state at the centers of quantum dots.

In the framework of the effective mass theory, this paper calculates the electron energy levels of an InAs/GaAs tyre-shape quantum ring (TSQR) by using the plane wave basis. The results show that the electron energy levels are sensitively dependent on the TSQR's section thickness d, and insensitively dependent on TSQR's section inner radius R1 and TSQR's inner radius R2. The model and results provide useful information for the design and fabrication of InAs/GaAs TSQRs.

The binding energy of a hydrogenic donor impurity in zinc-blende (ZB) InGaN quantum dot (QD) is calculated in the framework of effective-mass envelope-function theory using the plane wave basis. It is shown that the donor binding energy is highly dependent on the impurity position, QD size and the external electric field. The symmetry of the electron probability distribution is broken and the maximum of the donor binding energy is shifted from the centre of QD in the presence of the external electric field. The degenerating energy levels for symmetrical positions with respect to the centre of QD are split. The splitting increases with the increase of QD height while the splitting increases up to a maximum value and then decreases with the increase of QD radius.

Coherent tunnelling is studied in framework of the effective mass approximation for an asymmetric coupled quantum well. The Hartree potential due to the electron-electron interaction is considered in our calculation. The effects of the longitudinal and transverse magnetic field on coherent tunnelling characteristics are discussed. It has been found that the external field plays an important role in modulating the electron states.

The propagation property of metal wires terahertz waveguides is studied and simulated under the framework of the Sommerfeld model. The group velocity dispersion, attenuation amplitude, transverse magnetic mode and propagating energy have been obtained by numerically solving the complex eigenvalue equation for the propagation constant. It is found that the group velocity dispersion and attenuation amplitude decrease with the increasing radii of metal wires. The energy power within the dielectric layer increase with the increase of radiation frequency.

Sn-doped Ge2Sb2Te5 thin films deposited on Si(100)/SiO2 substrates by rf magnetron sputtering are investigated by a differential scanning calorimeter, x-ray diffraction and sheet resistance measurement. The crystallization temperatures of the 3.58 at.%, 6.92 at.% and 10.04 at.% Sn-doped Ge2Sb2Te5 thin films have decreases of 5.3, 6.1 and 0.9°C, respectively, which is beneficial to reduce the switching current for the amorphous-to-crystalline phase transition. Due to Sn-doping, the sheet resistance of crystalline Ge2Sb2Te5 thin films increases about 2–10 times, which may be useful to reduce the switching current for the amorphous-to-crystalline phase change. In addition, an obvious decreasing dispersibility for the sheet resistance of Sn-doped Ge2Sb2Te5 thin films in the crystalline state has been observed, which can play an important role in minimizing resistance difference for the phase-change memory cell element arrays.

We investigate the interface phonon assisted transition in GaAs/AlGaAs quantum cascade lasers (QCLs) by using the transfer matrix method based on the dielectric continuum model. Electron eigenvalues and eigenstates are calculated by solving Schrodinger equation and the Poisson equation self-consistently. The AlAs-like and upper GaAs-like interface phonon modes contribute most of the scattering rate. Interface phonon modes couple strongly with electrons at E2, and the magnitude of scattering rate between E2 and E1 is much larger than that between E3 and E1, which is helpful for the laser inversion between E3 and E2. The calculation can be easily applied to the design and simulation of QCLs.

The electronic structures, dielectric functions, complex refractive index and absorption spectra for the PbWO4 (PWO) crystal with and without oxygen vacancy VO2+ have been calculated using the full-potential (linearized) augmented planewave (FP-LAPW)+local orbitals (LO) method with the lattice structure optimized. The calculated results indicate that the optical properties of the PWO crystal show anisotropy and its optical symmetry coincides with the lattice structure geometry of the PWO crystal. The calculated absorption spectra indicate that the stoichiometric PWO crystal does not display absorption band in the visible and near-ultraviolet range. However, in this range, the absorption spectra of the PWO crystal containing VO2+ exhibit two peaks at 3.35eV (370nm) and 2.95eV (420nm), respectively. It is revealed that the 350nm and 420nm absorption bands are related to the existence of VO2+ in the PWO crystal.

One-dimensional quasicrystal structures composed of III-V semiconductor GaAs/AlGaAs multilayers in deterministic Thue–Morse (TM) sequences have been grown by using gas-source molecular beam epitaxy to investigate both the structural and the photonic bandgap properties. The x-ray measurements show that this aperiodic system exhibits obvious periodic spatial correlations, from which the precise thickness of the constitutive layers could be determined. Transmission and reflection measurements experimentally demonstrated plenty of photonic bandgaps with traditional or fractal features existing in those quasicrystal structures, which are in good agreement with the transfer matrix simulations. The diversity of this TM system makes it a good candidate for photonic device applications.

Ag-doped Ge2Sb2Te5 films were deposited by rf magnetron sputtering on SiO2/Si substrates. The content of Ag ranging from 4.5 to 11.3 at.% is determined by inductively coupled plasma atomic emission spectrometry. The crystallization temperature of Ag-doped Ge2Sb2Te5 increases with the increasing Ag content and the stability of phase change film is improved greatly. Structures were measured by x-ray diffraction and the face-centered-cubic structure was more stable after Ag doping. Four-point probe was used to measure the sheet resistance of Ag-doped Ge2Sb2Te5 films annealed at different temperatures and it is indicated that Ag atoms increase the sheet resistance of Ge2Sb2Te5 thin film when the annealing temperature is higher than about 360 degrees C, which is beneficial for reducing the reset current. Current-voltage curves were tested and it is demonstrated that 4.5 at.% Ag doping into the Ge2Sb2Te5 film can reduce the threshold current from 1.46 mA to 0.25 mA and can only increase the threshold voltage slightly, which is very useful for low energy consumption.

A single nano-cell-element of chalcogenide-random access memory was fabricated by using the focused ion beam method. The minimum contact size between the Ge2Sb2Te5 phase change film and the top electrode film for the cell element is with diameter of 60 nm. The reversible phase transition between the RESET state and the SET state was successively realized. The minimum SET current is obtained to be about 0.28 mA.