Sensitivity investigation of 100-MeV proton irradiation to SiGe HBT single event effect

The single event effect(SEE) sensitivity of silicon–germanium heterojunction bipolar transistor(Si Ge HBT) irradiated by 100-Me V proton is investigated. The simulation results indicate that the most sensitive position of the Si Ge HBT device is the emitter center, where the protons pass through the larger collector-substrate(CS) junction. Furthermore, in this work the experimental studies are also carried out by using 100-Me V proton. In order to consider the influence of temperature on SEE, both simulation and experiment are conducted at a temperature of 93 K. At a cryogenic temperature, the carrier mobility increases, which leads to higher transient current peaks, but the duration of the current decreases significantly.Notably, at the same proton flux, there is only one single event transient(SET) that occurs at 93 K. Thus, the radiation hard ability of the device increases at cryogenic temperatures. The simulation results are found to be qualitatively consistent with the experimental results of 100-Me V protons. To further evaluate the tolerance of the device, the influence of proton on Si Ge HBT after gamma-ray(^(60)Coγ) irradiation is investigated. As a result, as the cumulative dose increases, the introduction of traps results in a significant reduction in both the peak value and duration of the transient currents.

First-order primal-dual algorithm for sparse-view neutron computed tomography-based three-dimensional image reconstruction

Neutron computed tomography(NCT)is widely used as a noninvasive measurement technique in nuclear engineering,thermal hydraulics,and cultural heritage.The neutron source intensity of NCT is usually low and the scan time is long,resulting in a projection image containing severe noise.To reduce the scanning time and increase the image reconstruction quality,an effective reconstruction algorithm must be selected.In CT image reconstruction,the reconstruction algorithms can be divided into three categories:analytical algorithms,iterative algorithms,and deep learning.Because the analytical algorithm requires complete projection data,it is not suitable for reconstruction in harsh environments,such as strong radia-tion,high temperature,and high pressure.Deep learning requires large amounts of data and complex models,which cannot be easily deployed,as well as has a high computational complexity and poor interpretability.Therefore,this paper proposes the OS-SART-PDTV iterative algorithm,which uses the ordered subset simultaneous algebraic reconstruction technique(OS-SART)algorithm to reconstruct the image and the first-order primal–dual algorithm to solve the total variation(PDTV),for sparse-view NCT three-dimensional reconstruction.The novel algorithm was compared with other algorithms(FBP,OS-SART-TV,OS-SART-AwTV,and OS-SART-FGPTV)by simulating the experimental data and actual neutron projection experiments.The reconstruction results demonstrate that the proposed algorithm outperforms the FBP,OS-SART-TV,OS-SART-AwTV,and OS-SART-FGPTV algorithms in terms of preserving edge structure,denoising,and suppressing artifacts.

Al添加对Mg−Zn−Sn−Mn合金显微组织和力学性能的影响

通过光学显微镜(OM)、X射线衍射仪(XRD)、差示扫描量热仪(DSC)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和单轴拉伸试验,研究不同Al含量(0、0.5、1、2、3和4,质量分数,%)对铸态、均匀化态和挤压态Mg−6Zn−4Sn−1Mn(ZTM641)合金显微组织和力学性能的影响。结果表明:当Al含量不高于0.5%时,合金主要由α-Mg、Mg_(2)Sn、Al_(8)Mn_(5)和Mg_(7)Zn_(3)相组成;当Al含量高于0.5%时,合金主要由α-Mg、Mg_(2)Sn、MgZn、Mg_(32)(Al,Zn)_(49)、Al_(2)Mg_(5)Zn_(2)、Al_(11)Mn_(4)和Al_(8)Mn_(5)相组成;少量的Al(≤1%)可以增加热挤压过程中动态再结晶细小晶粒的比例。在室温拉伸试验条件下,ZTM641−1Al合金具有最佳的综合力学性能,其极限抗拉强度为332 MPa,屈服强度为221 MPa,伸长率为15%;在150和200℃高温拉伸试验条件下,ZTM641−2Al合金具有最佳的综合力学性能。

Application of pole-zero cancellation circuit in nuclear signal filtering and shaping algorithm

In radiation measurement and digital nuclear spectrum systems,traditional nuclear signal processing circuits in nuclear electronics have been gradually replaced by digital algorithm modules with the application of highperformance programmable hardware logic devices(such as FPGA or DSP).Referring to the digital realization method of inverse RC integral circuit systems,the function of the pole-zero cancellation(PZC)circuit was analyzed,a new modified cascade equivalent model of PZC was established,and the time-domain digital PZC(DPZC)recursive algorithm was derived in detail in this study.Two parameters kIand k_(D)are included in the new algorithm,where kIshould match the exponential decay time constant of the input signal to realize the pole-zero compensation,while the decay time constant of the output signal can be changed with the adjustable parameter k_(D)(which is larger than the decay time constant of the input signal).Based on the new DPZC algorithm module,two trapezoidal(triangular)shaping filters were designed and implemented.The amplitude–frequency characteristics of the output signal of the proposed trapezoidal shaping algorithm and the convolution trapezoidal shaping algorithm were compared,with fixed peaking time.The results show that the trapezoidal shaping algorithm based on DPZC can better suppress high-frequency noise.Finally,based on the Na I(Tl)scintillator(u75 mm×75 mm)detector and^(137)Cs source,the effect of the k_(D)value on the energy resolution of the DPZC trapezoidal(triangular)shaping algorithm was studied.The experimental results show that,with an increase in k_(D),the energy resolution of the system improved and reached the maximum when k_(D)was greater than 10,and the optimal energy resolution of the system was 7.72%.

Electronic structure and optical properties of the scintillation material wurtzite ZnS(Ag)

In order to investigate the effect of Ag doping(ZnS(Ag)) and Zn vacancy(V_(Zn)) on the alpha particle detection performance of wurtzite(WZ) ZnS as a scintillation cell component, the electronic structure and optical properties of ZnS, ZnS(Ag), and V_(Zn)were studied by firstprinciple calculation based on the density functional theory. The results show that the band gaps of ZnS, ZnS(Ag),and V_(Zn)are 2.17, 1.79, and 2.37 eV, respectively. Both ZnS(Ag) and V_(Zn)enhance the absorption and reflection of the low energy photons. A specific energy, about 2.9 eV,leading to decrease of detection efficiency is observed. The results indicate that Ag doping has a complex effect on the detection performance. It is beneficial to produce more visible light photons than pure WZ ZnS when exposed to the same amount of radiation, while the increase of the absorption to visible light photons weakens the detection performance. Zn vacancy has negative effect on the detection performance. If we want to improve the detection performance of WZ ZnS, Ag doping will be a good way,but we should reduce the absorption to visible light photons and control the number of Zn vacancy rigorously.

Low-energy(40 keV) proton irradiation of YBa_2Cu_3O_(7-x) thin films:Micro-Raman characterization and electrical transport properties

To investigate the damage profiles of high-fluence low-energy proton irradiation on superconducting materials and related devices, Raman characterization and electrical transport measurement of 40-keV-proton irradiated YBa_2Cu_3O_(7-x)(YBCO) thin films are carried out. From micro-Raman spectroscopy and x-ray diffraction studies, the main component of proton-radiation-induced defects is found to be the partial transition of superconducting orthorhombic phase to the semiconducting tetragonal phase and non-superconducting secondary phase. The results indicate that the defects induced in the conducting CuO_2 planes, such as increased oxygen vacancies and interstitials, can result in an increase in the resistivity but a decrease in the transition temperature TCwith the increase in the fluence of proton irradiation, which is confirmed in the electrical transport measurements. Especially, zero-resistance temperature TC_0 is not observed at a fluence of 10^(15)p/cm^2.Furthermore, the variation of activation energy U_0 can be explained by the plastic-flux creep theory, which indicates that the plastic deformation and entanglement of vortices in a weakly pinned vortex liquid are caused by disorders of point-like defects. Point-like disorders are demonstrated to be the main contribution to the low-energy proton radiation damage in YBCO thin films. These disorders are likely to cause flux creep by thermally assisted flux flow, which may increase noise and reduce the precision of superconducting devices.

3D robust anisotropic diffusion filtering algorithm for sparse view neutron computed tomography 3D image reconstruction

The most critical part of a neutron computed tomography(NCT) system is the image processing algorithm,which directly affects the quality and speed of the reconstructed images.Various types of noise in the system can degrade the quality of the reconstructed images.Therefore,to improve the quality of the reconstructed images of NCT systems,efficient image processing algorithms must be used.The anisotropic diffusion filtering(ADF) algorithm can not only effectively suppress the noise in the projection data,but also preserve the image edge structure information by reducing the diffusion at the image edges.Therefore,we propose the application of the ADF algorithm for NCT image reconstruction.To compare the performance of different algorithms in NCT systems,we reconstructed images using the ordered subset simultaneous algebraic reconstruction technique(OS-SART) algorithm with different regular terms as image processing algorithms.In the iterative reconstruction,we selected two image processing algorithms,the Total Variation and split Bregman solved total variation algorithms,for comparison with the performance of the ADF algorithm.Additionally,the filtered back-projection algorithm was used for comparison with an iterative algorithm.By reconstructing the projection data of the numerical and clock models,we compared and analyzed the effects of each algorithm applied in the NCT system.Based on the reconstruction results,OS-SART-ADF outperformed the other algorithms in terms of denoising,preserving the edge structure,and suppressing artifacts.For example,when the 3D Shepp–Logan was reconstructed at 25 views,the root mean square error of OS-SART-ADF was the smallest among the four iterative algorithms,at only 0.0292.The universal quality index,mean structural similarity,and correlation coefficient of the reconstructed image were the largest among all algorithms,with values of 0.9877,0.9878,and 0.9887,respectively.

基于流构全耦合模型的柱塞泵斜盘振动和压力脉动的研究（英文）

目的:航空柱塞泵是飞机液压系统的核心元件,具有高压高转速的特点,其压力脉动是飞机液压系统振动的主要激励源,对飞机液压系统的安全性和可靠性具有重要影响。本文首次全面分析了压力脉动和斜盘振动之间的关系,对降低柱塞泵的压力脉动、提高其可靠性具有重要理论意义。创新点:1.将柱塞泵压力脉动和斜盘振动相结合,综合分析两者相互作用关系;2.综合分析柱塞、斜盘控制阀、斜盘控制柱塞三者间的作用关系,建立全耦合模型。通过仿真分析和实验验证,指出普通模型的局限性以及全耦合模型在研究斜盘振动与压力脉动的真实内在关系的可靠性。方法:1.通过仿真和试验对比,分析全耦合模型和普通模型在压力脉动仿真结果上的差别及原因;2.通过对比分析,确定全耦合模型在斜盘振动仿真方面具有的较高精度;3.通过柱塞泵高压腔流量仿真结果,讨论柱塞泵压力脉动成因以及与斜盘的振动关系;4.通过斜盘力矩仿真分析讨论斜盘振动成因以及与压力脉动的关系;5.通过分析压力脉动、斜盘振动和转速三者间的关系,探讨减轻斜盘振动与减小压力脉动的有效途径。结论:1.全耦合模型的精确度比普通模型高,能较好地预测斜盘振动和压力脉动状态。2.斜盘振动的基频部分主要取决于压力脉动的动态特性,同时还受控制阀机构(FSI-3)和变量柱塞机构(FSI-2)的动态特性影响。压力脉动主要由柱塞泵的柱塞运动关系(FSI-1)决定,不受斜盘高频振动影响。

Coating highly lithiophilic Zn on Cu foil for high-performance lithium metal batteries

Lithium metal batteries(LMBs) are ideal candidates for next-generation high energy density energy storage systems.However,uncontrollable growth of Li dendrites due to uneven Li plating has restricted the practical application of the Li metal anode.Here,we develop a highly lithiophilic Zn coating on commercial Cu foil as a substrate for Li metal anode to settle above issues.We find that the lithiophilic nature of Zn can facilitate homogeneous nucleation and deposition of Li on Cu current collector surface.In addition,the uniform Zn coating can not only decrease the nucleation overpotential but also regulate the electric field distribution.Benefiting from the coated Zn layer,the designed anode for half-cell and full-cell tests shows better electrochemical performances compared with the untreated Cu foil.This work provides a simple and effective way to enable a promising dendrite-free lithium metal anode for large-scale industrial applications.

Directed Self-assembly of Vertical PS-b-PMMA Nanodomains Grown on Multilayered Polyelectrolyte Films

Layer-by-layer polyelectrolyte self-assembly, a common method for preparing high-quality ultra-thin films, was employed to direct the self-assembly behavior of polystyrene-block-poly(methyl methacrylate)(PS-b-PMMA) block copolymer for the first time. Differing from the previous neutral polymer brushes anchored to silicon substrates via chemical modification, polyelectrolyte multilayers(PEMs) were anchored by electrostatic interaction and provided a stable, smooth, and neutral interface. In the present study, PS-b-PMMA was deposited on poly(acrylamide hydrochloride)/poly(acrylic acid)(PAH/PAA) PEMs prepared by layer-by-layer self-assembly to successfully yield vertical nanodomains after thermal annealing. Seven layered PEMs revealed an excellent, smooth surface, with a low roughness of 0.6 nm. The periodic structure with interlamellar spacing of 47 nm was determined by grazing-incidence small-angle X-ray scattering(GISAXS). The morphology of the PS-b-PMMA nanodomains depended on the polyanion-to-polycation concentration ratio, which is related to the interaction between the block copolymer and the substrate. Our results demonstrate that layer-by-layer self-assembly is a helpful method for the phase separation of block polymers and the fabrication of vertical, ordered nanodomains.

Comparison and research on the GRAVEL and PRIP algorithms of neutron energy spectrum unfolding

Objective Neutron energy spectrum unfolding is a key technique for neutron detection.It is essentially an inversion problem.The GRAVEL algorithm has been widely used in this field,and the PRIP algorithm transforms neutron energy spectrum unfolding into a typical nonnegative linear complementarity problem and solves it by interior point algorithm for potential reduction.Methods These two algorithms are applied to unfold several different neutron energy test spectra and actual D-T fusion neutron energy spectrum.Results and Conclusion By comparison,it can be concluded that the PRIP algorithm is highly computationally efficient and fast converging,and the GRAVEL algorithm solution results match up more with the expected results.

液压机器人增压油箱的多目标优化方法研究（英文）

目的:增压油箱是提高液压机器人动力源功率密度的一个关键元件。高集成度的增压油箱设计涉及6个设计变量和6个性能指标,必须采用合适的方法进行多目标优化。创新点:1.提出一种在设计变量平面上投影性能曲面的多目标优化方法,通过设定性能阈值缩小可行解范围并获得决策;2.将增压油箱应用于液压机器人,提高液压机器人的功率密度和性能。方法:1.采用活塞-弹簧增压的原理来实现机器人液压系统增压,分析增压油箱的容量、质量和增压压力等性能,确定增压油箱设计为多目标优化问题。2.通过在设计变量平面上的投影曲面,分析增压油箱性能指标与设计变量之间的关系;将目标函数阈值引入设计限制条件,通过控制待优化的指标缩小可行域,获得油箱设计的最终解。3.按优化设计参数加工油箱样机,并在液压机器人动力源上进行测试。结论:1.增压油箱优化结果表明本文提出的设计方法可帮助设计者获得所需的最优解;2.增压油箱样机的应用测试结果表明所研制的增压油箱在液压机器人系统中运行可靠。

A transient process observation method based on the non-homogeneous Poisson process model

The current-mode-counting method is a new approach to observing transient processes,especially in transient nuclear fusion,based on the non-homogeneous Poisson process(NHPP)model.In this paper,a new measurement process model of the pulsed radiation field produced by transient nuclear fusion is built based on the NHPP.A simulated measurement is performed using the model,and the current signal from the detector is obtained by simulation based on Poisson process thinning.The neutron time spectrum is reconstructed and is in good agreement with the theoretical value,with its maximum error of a characteristic parameter less than 2.3%.Verification experiments were carried out on a CPNG-6 device at the China Institute of Atomic Energy,with a detection system with a nanosecond response time.The experimental charge amplitude spectra are in good agreement with those obtained by the traditional counting mode,and the characteristic parameters of the time spectrum are in good agreement with the theoretical values.This shows that the current-mode-counting method is effective for the observation of transient nuclear fusion processes.