•A multifunctional sensor is proposed for magnetic testing technique.•Mean impact value evaluation algorithm is combined with BP neural network.•Quantitative prediction of tensile stress, surface ...hardness and case depth is achieved.
The simultaneous quantitative prediction of three target properties (tensile stress, surface hardness and case depth) in medium carbon steel rods based on magnetic nondestructive testing techniques was experimentally investigated. A multifunctional sensor is proposed to simultaneously measure the magnetic Barkhausen noise, tangential magnetic field and magnetic hysteresis curve of the tensioned steel rods with different depths of surface hardened layer. Mean impact value evaluation algorithm is introduced to select the optimal combination from the sixteen candidate feature parameters, which are extracted from the measured signals, as the input nodes of BP neural network. For the two types of rods of 45 steel rods and 42CrMo steel, the established BP prediction model possesses good accuracy in simultaneous quantitative prediction of the three target properties. The maximum prediction error for surface hardness is less than 1.6%. The average prediction error for tensile stress case is around 5.1% in 45 steel rods and 5.3% in 42CrMo steel rods. Under the tensile stress higher than 40 MPa, the average prediction error is less than 3.4%. Although the BP prediction model may lose resolution in distinguishing small changes in the case depth around 0.07 mm, the average prediction error of case depth in both types of medium carbon steel rods is lower than 5%.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
In implosion experiments, bremsstrahlung radiation ratios of broad-energy-band x-ray emission intensities (sampled by Ross pair) and narrow-energy-band x-ray emission intensities (sampled by ...multilayer) are typically used to extract the hotspot electron temperature. The latter method could potentially be more accurate because it does not require any additional theoretical arithmetic. However, the boundary conditions of the energy band, drastic influence on the measured electron temperature resulting from response differences of recording devices in the energy band, evident impact from uncertainties of the detector aiming, and coordinate interrelations for the two narrow-energy-band x-ray images have not been explored. These problems should be overcome to obtain the accurate hotspot electron temperature using the narrow-energy-band x-ray emission intensities method. This study solves the problems indicated above by exploring a diagnosis technique to extract the accurate hotspot electron temperature. In particular, we determine that the effect of the response differences and uncertainties could be ignored when the width of the sampled narrow energy band is approximately ±0.5 keV in the linear spectrum response regions of the imaging plate, and the reflectivity of the multilayer is uniform and constant in that energy band and the viewing field of the detector (≥±110 µm). This study is the first to consider the linear spectrum response of the imaging plate in different energy regions, eliminating the effect of the response differences. Finally, the maximal emission intensities in the two recorded-energy-band x-ray images can be used for coordinate interrelation.
A high-neutron yield platform imploded by a thin shell target is generally built to probe nuclear science problems, and it has the advantages of high neutron yield, ultrashort fusion time, micro ...fusion zone, isotropic and monoenergetic neutron. Some analytical models have been proposed to interpret exploding-pusher target implosion driven by a long wavelength laser, whereas they are imperfect for a 0.35 μm laser implosion experiment. When using the 0.35 μm laser, the shell is ablated and accelerated to high implosion velocity governed by Newton’s law, ablation acceleration and quasi-adiabatic compression models are suitable to explain the implosion of a laser direct-drive thin shell target. The new analytical model scales bang time, ion temperature and neutron yield for large variations in laser power, target radius, shell thickness, and fuel pressure. The predicted results of the analytical model are in agreement with experimental data on the Shenguang-III prototype laser facility, 100 kJ laser facility, Omega, and NIF, it demonstrates that the analytical model benefits the understanding of experiment performance and optimizing the target design of high neutron yield implosion.
In this paper a modelling study is performed to investigate the frequency scaling laws in atmospheric radio frequency discharges. By introducing the relaxation frequency of discharge plasmas, which ...links the electron density and excitation frequency, the relationships between excitation frequency and other discharge parameters, such as electron density, current density and sheath thickness, are revealed based on the analytical equations deduced from the model and then confirmed by the computational data. These scalings are effective to give insights into some discharge parameters which are not easily accessible in experiments such as electron density.
Several scaling laws were obtained based on the analytical equations and computational data in radio‐frequency discharges at atmospheric pressure. By introducing the relaxation frequency of plasmas generated in gas gap, the governing equations of atmospheric radio‐frequency discharges can be effectively simplified to reveal the frequency scalings, and the simulation results agree well with the theoretical prediction.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
•X-ray emissions of laser produced Au foam plasmas are investigated.•X-ray spectral characteristics and conversion efficiency are measured.•Experimental and theoretical spectral distributions agree ...with each other.
The X-ray emission properties of Au plasmas consist of spectral distribution, M band fraction (2–4keV), X-ray angular distribution and X-ray conversion efficiency, are imperative for various X-ray source applications. In order to investigate the X-ray emission properties of laser produced plasmas with Au and Au foam targets, experiments were carried out in Shenguang II laser facility. Au foam targets with densities of 0.6 and 0.4g/cm3 were employed. The X-ray emission properties were measured. Excellent agreements of the experimental and theoretical spectral distributions and M band fractions were achieved.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Despite intensive search over the past decades, only a few small-molecule DNA fluorescent dyes were found with large Stokes shifts. These molecules, however, are often too toxic for widespread usage. ...Here, we designed DNA-specific fluorescent dyes rooted in benzimidazole architectures with a hitherto unexplored molecular framework based on thiazole-benzimidazole scaffolding. We further incorporated a pyrazole ring with an extended sidechain to prevent cell penetration. These novel benzimidazole derivatives were predicted by quantum calculations and subsequently validated to have large Stokes shifts ranging from 135 to 143 nm, with their emission colors changed from capri blue for the Hoechst reference compound to iguana green. These readily-synthesized compounds, which displayed improved DNA staining intensity and detection limits along with a complete loss of capability for cellular membrane permeation and negligible mutagenic effects as designed, offer a safer alternative to the existing high-performance small-molecule DNA fluorescent dyes.
•Innovative Thiazole-Benzimidazole Scaffold in DNA Dyes with large Stokes shifts and minimal genotoxicity.•Efficient Synthesis and Biophysical Properties of Benthio Green-1 to Benthio Green-5 DNA dyes.•Superior Performance of Benthio Green-4 with a 50% improvement over Hoechst 33342 and a low detection limit of 1 ng compared to 8 ng for Hoechst 33342.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
The state of the microstructures determines both the mechanical properties (hardness, yield strength, elongation, etc.) and micro-magnetic properties (magnetic Barkhausen noise (MBN), ...incremental permeability (IP), etc.). The non-destructive nature of the micro-magnetic testing technology facilitate it be a valuable tool for quality control in the manufacturing of ferromagnetic components. In the implementation of micro-magnetic testing, the functions and the geometry of the sensors need be customized for specific target properties and components. In this paper, four types of advanced or multifunctional sensors are presented and applied for micro-magnetic testing. First, a multifunctional sensor is developed for flat surface. Unique intermittent magnetizing method using superimposed magnetic fields of high and low frequencies enable the sensor to measure the magnetic Barkhausen noise, incremental permeability, eddy currents, tangential magnetic field and main flux. Second, to conduct magnetic Barkhausen noise testing at the inner corner of V-shape bending plate, a miniaturized sensor with U-shape roller magnetizer is designed to perfect contact with the corner region. Third, read head of a magnetic tape player is revised to act as high-lateral-resolution (up to 500μm) sensor for magnetic Barkhausen noise measurement in ferromagnetic film. Fourth, a slender probe is developed and embedded into an anti-bulking fixture that is clamped onto the flat specimen. With the slender probe together with the special fixture, the dependency of the magnetic Barkhausen noise on the compressive and tensile stress is first experimentally observed in a single flat specimen under continuous load.
Since the permeability of ferromagnetic materials is sensitive to the stress changes, it is feasible to acquire the stress level through detecting the change in permeability. In this study, to ...explore the distribution of stress or residual stress along the depth direction, a multi-layer model was established and a new inversion algorithm was proposed; and the hypothesis of uniformity of the material's physical properties for each layer was introduced. Under laboratory conditions, the four-point bending experiment was then implemented with a sample of 45# steel. Global Fourier series fitting based on the least-squares method was used for signal process. The amplitude ratio of the induced voltage to the excitation current was extracted. The effective permeability and the associated hysteresis angle at the 0.25 mm deflection were calculated and presented good regular variations. Finally, under the 0.25 mm deflection, the effective permeability change along the depth was obtained, and the inversely fitted curve was consistent with the theoretical curve. It is verified that the sensor has good robustness by adding deviation of the detection depth. Thereby, it is feasible to test stress or residual stress as a function of depth by multi-frequency eddy current (EC) method.
Under-critical CH foam coated gold targets benefit laser-to-x-ray emission because CH plasma inhibits gold plasma expansion, which leads to higher gold plasma density and temperature. Conversely, the ...CH foam partially absorbs the incident laser energy, which lowers laser absorption into the gold plasma. An analytical model is built to solve the laser collisional deposition fraction in the CH foam layer. The optimization of x-ray emission from under-critical CH foam coated gold targets by laser irradiation is obtained numerically with different CH foam densities and thicknesses. The plasma and x-ray emission properties are investigated. It is found that different CH thicknesses lead to different increase mechanisms for x-ray emission. The x-ray spectrum distributions show that most of the x-ray emission increases occur with photon energy less than 2000 eV.
A new method for measuring the time-dependent drive flux at the hohlraum center is proposed as a better alternative to conventional wall-based techniques. The drive flux here is obtained by ...simultaneous measurement of the reemitted flux and shock velocity from a three-layered "cakelike" sample. With these two independent observables, the influence induced by the uncertainty of the material parameters of the sample can be effectively decreased. The influence from the closure of the laser entrance hole, which was the main challenge in conventional wall-based techniques, was avoided through localized reemitted flux measurement, facilitating drive flux measurement throughout the entire time history. These studies pave a new way for probing the time-dependent drive flux, for both cylindrical hohlraums and novel hohlraums with six laser entrance holes.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UL, UM
