分类: 工程与技术科学 >> 物理学相关工程与技术 分类: 工程与技术科学 >> 仪器仪表技术 分类: 电子与通信技术 >> 电子技术 分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2024-05-06
摘要: 本文提出了一种用于低温扫描隧道显微镜(CryoSTM)的跨阻放大器(TIA)设计方案。在CryoSTM中带有尖端样品成分的TIA称为CryoSTM-TIA。该CryoSTM-TIA的跨阻增益在1Gohm,而其带宽大于300kHz。所提出的CryoSTM-TIA的独特特点是其前置放大器由单个低温高电子迁移率晶体管(HEMT)制成,因此在100kHz时仪器等效输入噪声电流功率谱密度低于4(fA)2/Hz。此外,应用“偏置冷却法”可用于原位控制HEMT掺杂区冻结DX-中心的密度,改变其结构以降低器件噪声。利用该仪器,可以进行高能量分辨率的快速扫描隧道光谱测量。并且,它能够测量各种量子系统在原子尺度上的扫描隧道散粒噪声谱(STSNS),即使散粒噪声非常低。它为通过测量STSNS来研究新的量子态提供了一个强大的工具,例如检测拓扑量子系统中马约拉纳束缚态的存在。
分类: 电子与通信技术 >> 电子技术 分类: 工程与技术科学 >> 仪器仪表技术 分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 分类: 物理学 >> 凝聚态:电子结构、电、磁和光学性质 提交时间: 2024-05-06
摘要: In this work, we design and fabricate the transimpedance Amplifier (TIA) following the design mentioned in Ref. cite{Liang2024}. In the TIA, the preamplifier (Pre-Amp) is made of a junction field effect transistor (JFET) that can work at 77 K. The post-amplifier is made of an operational amplifier (OPA). Cascade Pre-Amp and Post-Amp to form the inverting-amplifier (Inv-Amp). The gain-bandwidth product of Inv-Amp with the gain about 50,000 is higher than 10 GHz. With a 1.13 Gohm feedback network, the gain of TIA is 1.13 Gohm and its bandwidth is about 97 kHz. The equivalent input noise voltage power spectral density of TIA is not more than 9 (nV)2/Hz at 10 kHz and 4 (nV)2/Hz at 50kHz, and its equivalent input noise current power spectral density is about 26 (fA)2/Hz at 10 kHz and 240(fA)2/Hz at 50 kHz. The measured transport performances and noise performances of TIA are consistent with the simulations and calculations, verifying the feasibility for the design of low-noise large-bandwidth TIA proposed in Ref. 1 . And, TIA with various performances that meet various needs can be designed according to the design methods in Ref. 1,2 . With the same gain, the bandwidth of the TIA in this work is much larger than the present TIA and its noises are much lower than those of present ones. The TIA in this work is perfect for the cryogenic STM working at 77 K (i.e. liquid nitrogen temperature).
分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2024-03-23
摘要: To predict the fractal decoded image quality more efficiently, an accumulated collage error coefficient (ACEC) based method was proposed in this study. Firstly, the definition of ACEC was introduced to describe the relationship among the upper bound, lower bound, and actual value of theaccumulated collage error of all range blocks. Moreover, the definition and monotonicity of the relative error of ACEC were also defined and discussed. While the relative error of ACEC reaches a relatively small value, the average collage error (ACER) can be estimated approximately, and then the encoding process can be terminated to directly predict the peak signal-to-noise ratio (PSNR) quality of decoded images. Experimental results show that compared with the previous method, the proposed method can predict the decoded image quality more accurately with fewer computations.
分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 分类: 材料科学 >> 陶瓷学 提交时间: 2024-03-20
摘要: 高放废物固化体的长期辐照稳定性是评价其深地质处置安全性的关键指标之一。本文利用 500 keV He2+离子束辐照 2M、 3O 和 4M 型钙钛锆石陶瓷固化体, 研究高放核素长期α 衰变辐照对陶瓷结构的损伤行为。三种钙钛锆石样品通过传统高温固相法(1400 ℃, 48h两次烧结)合成。掠入射 X 射线衍射(GIXRD) 、 Raman 光谱和 XPS 研究结果发现在 α 粒子辐照下, zirconolite-2M 固化体在辐照非晶化的过程中经历了 zirconolite-2M 到 zirconolite-4M 到 pyrochlore 的结构演变; zirconolite-3O 在 5×1015 ions/cm2 剂量下部分晶体结构转变为钙钛矿,在 1×1016 ions/cm2 以上剂量快速转变为无序烧绿石; zirconolite-4M 样品在 1×1017 ions/cm2 剂量时依旧保留 zirconolite-4M 主相,次生无序烧绿石/缺陷萤石晶相。综上, 从维持晶体结构稳定性来看 zirconolite-2M 和 zirconolite-3O 的抗 α 粒子辐照能力相似,略弱于zirconolite-4M 固化体。
分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2024-02-27
摘要: The energy storage and conversion found in ferroelectrics realize through polar domain and domain wall microstructures resulted in complex polar topologies or within transformations from macro/micro domain to nano domain. The physical models are adopted with basic domains and domain walls including 90o, 180o, 71o and 109o classified into two categories of 180o and α-angle, and are reconstructed with equivalent circuits simplified according to the reported patterns. Although electrical energy is known to be maintained by the balance of charging and loss, the effect of circuits on microstructure has been rarely explored because of the relative paucity of patterns implemented experimentally for domain and domain wall. And here the diagrammatic sketches of vortex pattern and transformation into nano domain are designed and derived into their respective formulas of total capacitance and energy density with crucial structural features. The findings reveal novel mechanisms on energy storage by microstructures that can be used to propose effective creation strategies even in designing modern measure equipment.
分类: 心理学 >> 认知心理学 分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 分类: 医学、药学 >> 基础医学 提交时间: 2024-01-21
摘要: The non-exclusive dual-process working model proposed in De Neys article effectively makes up for the shortcomings of the existing theories and models, but the explanation of the switching problem and the exclusivity problem in this article cannot constitute a complete rejection of the existing switching mechanism and the traditional fast-slow dual-process model. We believe that a more powerful and logical way of explaining the theory is as follows: human reasoning process is related to the complexity of the problem being faced, and it is also closely related to the reading process of the problem; in the process of reading the problem, the brain will automatically choose different ways of reasoning for the problem of different levels of complexity; and in the process of selection, the principle of minimum energy should still be valid.
分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2024-01-17
摘要: A 20-kiloton liquid scintillator detector is designed in the Jiangmen Underground Neutrino Observatory (JUNO) for multiple physics purposes, including the determination of the neutrino mass ordering through reactor neutrinos, as well as measuring supernova neutrinos, solar neutrinos, and atmosphere neutrinos to explore different physics topics. Efficient reconstruction algorithms are needed to achieve these physics goals in a wide energy range from MeV to GeV. In this paper, we present a novel method for reconstructing the energy of events using hit information from 3-inch photomultiplier tubes (PMTs) and the OCCUPANCY method. Our algorithm exhibits good performance in accurate energy reconstruction, validated with electron Monte Carlo samples spanning kinetic energies from 10~MeV to 1~GeV.
分类: 物理学 >> 核物理学 分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2024-01-10
摘要: Traditional particle identification methods are time consuming, experience-dependent, and poor repeatability challenges in heavy-ion collisions at low and intermediate energies. Researchers urgently need solutions to the dilemma of traditional particle identification methods. This study explores the possibility of applying intelligent learning algorithms to the particle identification of heavy-ion collisions at low and intermediate energies. Multiple intelligence algorithms, including XgBoost and TabNet, were selected to test datasets from the neutron ion multi-detector for reaction-oriented dynamics (NIMRODISiS) and Geant4 simulation. Machine learning algorithms based on tree structures and deep learning algorithms e.g. TabNet show excellent performance and generalization ability. Adding additional data features besides energy deposition can improve the algorithm's identification ability when the data distribution is nonuniform. Intelligent learning algorithms can be applied to solve the particle identification problem in heavy-ion collisions at low and intermediate energies.
分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2023-11-30
摘要: 基于动电效应的来源于固/液接触双电层的能量转换是动生电动势,本文研究静态显现和释放固/液接触双电层电场能的静生电动势,为此构建了固态导体P/极性液体L/固态导体N的特殊电容器(P/L/N电容器)。研究发现:(i)由固态导体/极性液体内电位差极化出的接触双电层与普通电容器外加电场极化出的双电层等效,接触双电层的形成过程就是P/L/N电容器自发充电过程,P/L/N电容器静态显现接触双电层电场能。(ii)因为固态导体/极性液体接触双电层的极化外电位差总是小于其内电位差,所以放电后的短路的P/L/N电容器还有一个持续的电动势,静态释放接触双电层的电场能。(iii)固态导体/极性液体的接触双电层是因相互接触而自发产生的,也是一个吸取环境热能转换为接触双电层电场能的自组织过程,P/L/N电容器通过释放接触双电层的电场能实现热电转换。这为研发自生电电容器、自供电电源等提供了可能。
分类: 信息科学与系统科学 >> 信息科学与系统科学基础学科 分类: 生物学 >> 生物进化论 分类: 生物学 >> 生物数学 分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 分类: 生物学 >> 遗传学 提交时间: 2023-10-15
摘要: Background: In bioinformatics, tools like multiple sequence alignment and entropy methods probe sequence information and evolutionary relationships between species. Although powerful, they might miss crucial hierarchical relationships formed by the reuse of repetitive subsequences like duplicons and transposable elements. Such relationships are governed by evolutionary tinkering'', as described by Fran c{c}ois Jacob. The newly developed Ladderpath theory provides a quantitative framework to describe these hierarchical relationships.Results: Based on this theory, we introduce two indicators: order-rate $ eta$, characterizing sequence pattern repetitions and regularities, and ladderpath-complexity $ kappa$, characterizing hierarchical richness within sequences, considering sequence length. Statistical analyses on real amino acid sequences showed: (1) Among the typical species analyzed, humans possess relatively more sequences with large $ kappa$ values. (2) Proteins with a significant proportion of intrinsically disordered regions exhibit increased $ eta$ values. (3) There are almost no super long sequences with low $ eta$. We hypothesize that this arises from varied duplication and mutation frequencies across different evolutionary stages, which in turn suggests a zigzag pattern for the evolution of protein complexity. This is supported by our simulations and examples from protein families such as Ubiquitin and NBPF.Conclusions: Our method emphasizes how objects are generated'', capturing the essence of evolutionary tinkering and reuse. The findings hint at a connection between sequence orderliness and structural uncertainty, and suggest that different species or those in varied environments might adopt distinct protein elongation strategies. These insights highlight our method's value for further in-depth evolutionary biology applications.
分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2023-09-19
摘要: To accelerate the fractal decoding process, a minimum iterated function system based fast fractal decoding method was proposed in this study. In fractal encoding process, we found that there exists a minimum domain block set (MDBS) which can provide the best-matched domain blocks for all range blocks, and then the domain blocks of MDBS, the range blocks within MDBS, and the associated mapping operations between them constitute the minimum iteration function system (MIFS). In decoding process, MIFS was first recovered in the first iteration. Then, in each of the second to penultimate iterations, only the range blocks within MDBS are reconstructed, and the computations of reconstructing the remaining range blocks can be saved. Finally, all range blocks are reconstructed to obtain the decoded image in the last iteration. Four fractal encoding methods were adopted to assess the performance of the proposed method. Experimental results show that the proposed method can complete the decoding process with fewer computations.
分类: 物理学 >> 电磁学、光学、声学、传热、经典力学和流体动力学 分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2023-07-12
摘要: I review the discovery as well as the band structure of the Zhang lattice.
分类: 数学 >> 应用数学 分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2023-07-04
摘要: 伪随机数发生器(PRNG)广泛应用于许多领域,尤其是在密码应用中。设计欠佳的PRNG生成的序列将导致其密钥较弱从而可能泄漏被隐藏的信息。基于Golomb对理想伪随机序列的假设和FIPS 140-2随机性检验准则,本文首次提出了一种改进伪随机序列伪随机性能的新方法。其次,用广义同步定理、Henon映射、logistic映射和tube射构造了一个新的8维混沌广义同步系统(8DCGSS)。然后使用8DCGSS设计了一个混沌PRNG(CPRNG)。CPRNG的密钥空间大于2^{1117}。用FIPS 140-2随机性测试规范和广义FIPS 140-2随机性测试规范分别检测了CPRNG、Matlab PRNG、RC4算法和m序列分别生成的1000条20 000比特长的密钥流的通过率,应用广义FIPS 140-2随机性测试规范分别评估了改进的密钥流流的通过率(伪随机性)。用FIPS 140-2和广义FIPS 140-2伪随机性测试规范分别评估了4个PRNG产生的1000条100 000比特长的密钥流和1000条1 000 000比特长的密钥流和改进的密钥流的通过率。结果表明,本文的方法能够显著提高四个PRNGs生成的密钥流的伪随机性。m序列伪随机数发生器生成的长度小于100 000比特的密钥流的伪随机性能不佳。
分类: 物理学 >> 核物理学 分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2023-06-21
摘要: Collinear laser spectroscopy is known as one of the powerful tools for the study of nuclear spins, electromagnetic moments and charge radii of the exotic nuclei. Aiming at studying these nuclear properties of unstable nuclei at the Beijing Radioactive Ion-beam Facility (BRIF) and the future High Intensity Heavy-ion Accelerator Facility (HIAF), we have firstly developed a collinear laser spectroscopy apparatus integrated with an offline laser ablation ion source and a laser system. The overall performances of this state-of-the-art technique and device have been commissioned by using the bunched stable ion beam. High-resolution optical spectra of $^{40,42,44,48}$Ca isotopes were successfully measured for the 4$s$ $^{2}S_{1/2}$ $ rightarrow$ 4$p$ $^{2}P_{3/2}$ (D2) ionic transition and the extracted isotope shifts relative to the $^{40}$Ca show an excellent agreement with the literature values. This system is now ready to be applied at the ratioactive ion beam facility, such as BRIF, and has paved the way for further development of the higher-sensitivity collinear resonant ionization spectroscopy.
分类: 物理学 >> 核物理学 分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2023-06-20
摘要: The Shanghai laser electron gamma source (SLEGS) is a powerful tool for exploring photonuclear physics, such as giant dipole resonance (GDR) and pygmy dipole resonance, which are the main mechanisms of collective nuclear motion. The goal of the SLEGS neutron time-of-fight (TOF) spectrometer is to measure GDR and specifc nuclear structures in the energy region above the neutron threshold. The SLEGS TOF spectrometer was designed to hold 20 sets of EJ301 and LaBr3 detectors. Geant4 was used to simulate the efciency of each detector and the entire spectrometer, which provides a reference for the selection of detectors and layout of the SLEGS TOF spectrometer. Under the events of 208Pb, implementations of coincidence and time-of-fight technology for complex experiments are available; thus, y and neutron decay events can be separated. The performance of SLEGS TOF spectrometer was systematically evaluated using ofine experiments, in which the time resolution reached approximately 0.9ns.
分类: 核科学技术 >> 粒子加速器 分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2023-05-30
摘要: In this paper, we propose a novel stacked laser dielectric acceleration structure. This structure is based on the inverse Cherenkov effect and represented by a parametric design formulation. Compared to existing dielectric laser accelerators relying on the inverse SmithPurcell effect, the proposed structure provides an extended-duration synchronous acceleration field without requiring the pulse front tilting technique. This advantage significantly reduces the required pulse duration. In addition, the easy-to-integrate layered structure facilitates cascade acceleration, and simulations have shown that low-energy electron beams can be cascaded through high gradients over extended distances. These practical advantages demonstrate the potential of this new structure for future chip accelerators.
分类: 电子与通信技术 >> 电子技术 分类: 工程与技术科学 >> 物理学相关工程与技术 分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 分类: 工程与技术科学 >> 仪器仪表技术 提交时间: 2023-05-01
摘要: In this work, a design of large-bandwidth high-gain low-noise transimpedance amplifier (TIA) for scanning tunneling microscope (STM) is proposed. The simulations show that the proposed TIA has the bandwidth higher than 200 kHz, two orders of magnitude higher than those of conventional commercial TIAs for STM. At low frequencies, the noises of the proposed TIA are almost the same as the conventional commercial ones with the same transimpedance gain. At high frequencies, its calculated input equivalent noise voltage power spectral density (PSD) is 40 (nV)2/Hz and its input equivalent noise current PSD is 3.2 (fA)2/Hz at 10 kHz. The corresponding values are 23 (nV)2/Hz and 88 (fA)2/Hz at 100 kHz. The STM with the proposed TIA can meet the needs of fast high-quality STM imaging measurements and fast high-energy-resolution scanning tunneling spectra measurements for the low-conducting materials, such as complex organic systems and wide bandgap semiconductors.
分类: 工程与技术科学 >> 物理学相关工程与技术 分类: 工程与技术科学 >> 仪器仪表技术 分类: 电子与通信技术 >> 电子技术 分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2023-05-01
摘要: An ultra-low-noise large-bandwidth transimpedance amplifier (TIA) for cryogenic scanning tunneling microscope (CryoSTM) is proposed. The TIA connected with the tip-sample component in CryoSTM is called as CryoSTM-TIA. Its transimpedance gain is as high as 1 G, and its bandwidth is over 300 kHz, but its equivalent input noise current power spectral density is less than 4 (fA)2/Hz at 100 kHz. The low inherent noise for the CryoSTM-TIA is due to its special design: (1) its pre-amplifier is made of a pair of low-noise cryogenic high electron mobility transistors (HEMTs); (2) the noise generated by one HEMT is eliminated by a large capacitor; (3) the capacitance of the cable connected the gate of the other HEMT to the tip is minimized; (4) thermal noise sources, such as the feedback resistor, are placed in the cryogenic zone. The dc output voltage drift of the CryoSTM-TIA is very low, as 5 V/C. The apparatus can be used for measuring the scanning tunneling differential conductance spectra, especially the scanning tunneling shot noise spectra (STSNS) of quantum systems, even if the shot noise is very low. It provides a universal tool to study various novel quantum states by measuring STSNS, such as detecting the Majorana bound states.
分类: 工程与技术科学 >> 物理学相关工程与技术 分类: 工程与技术科学 >> 仪器仪表技术 分类: 电子与通信技术 >> 电子技术 分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2022-12-29
摘要: 提出了一种用于低温扫描隧道显微镜(CryoSTM)的低噪声高增益大带宽跨阻放大器(TIA)。在CryoSTM中与尖端样品组件连接的TIA称为CryoSTM-TIA。CryoSTM-TIA的跨阻增益为10Gohm,带宽超过100kHz,在100kHz时等效输入噪声电流功率谱密度小于4(fA)2/Hz。CryoSTM-TIA的低固有噪声是由于其特殊的设计: (1)其前置放大器(Pre-Amp)由低噪声低温高电子迁移率晶体管制成; (2)前置放大器采用卡片式配置,避免米勒效应,降低输入电容CA; (3)将前置放大器输入端连接到尖端的电缆的电容,即CI最小化; (4)热噪声源,如反馈电阻,放置在低温区。由于在反馈回路中应用了频率补偿,减小了CA,减小了CI,实现了高增益和大带宽。该仪器可用于低电导率材料扫描隧道光谱的快速高能量分辨率测量,特别是用于测量其扫描隧道发射噪声谱。
分类: 工程与技术科学 >> 物理学相关工程与技术 分类: 工程与技术科学 >> 仪器仪表技术 分类: 电子与通信技术 >> 电子技术 分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2022-12-29
摘要: 散粒噪声是一个研究量子体系的强有力的手段。本文提出一种用于低温扫描隧道显微镜 (CryoSTM)的跨阻放大器(TIA),可满足散粒噪声测量的需要。在该TIA中,前置放大器(Pre-Amp)由超低噪声低功率低温高电子迁移率晶体管(HEMTs)构成。以1Gohm的高跨阻增益,所设计的TIA的带宽超过300 kHz。在CryoSTM中,这个TIA连同针尖-样品组件和输入信号被称为CryoSTM-TIA。它的带宽仍然超过300kHz,并且它的等效输入噪声电流功率谱密度在100 kHz小于30 (fA)2/Hz。该CryoSTM-TIA能够用于测量扫描隧道电流谱和扫描隧道微分电导谱。本文又特别阐述了如何用该CryoSTM-TIA测量量子体系的扫描隧道噪声电流功率谱和散粒噪声谱。这就使得用低温CryoSTM-TIA通过测量散粒噪声来研究各种量子体系中的新奇量子现象成为可能,例如在局域尺度中的Andreev反射、在单分子磁体中的Kondo效应,等等。特别是把它用于研究与实现拓扑量子计算有关的Majorana零能模的存在性。