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  • Low-noise large-bandwidth high-gain transimpedance amplifier for cryogenic STM at 77 K

    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: 2024-04-23

    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).

  • SteganoDDPM: A high-quality image steganography self-learning method using diffusion model

    分类: 计算机科学 >> 信息安全 分类: 计算机科学 >> 计算机应用技术 提交时间: 2024-04-23

    摘要: Image steganography has become a focal point of interest for researchers due to its capacity for the covert transmission of sensitive data. Traditional diffusion models often struggle with image steganography tasks involving paired data, as their core principle of gradually removing noise is not directly suited for maintaining the correspondence between carrier and secret information. To address this challenge, this paper conducts an in-depth analysis of the principles behind diffusion models and proposes a novel framework for an image steganography diffusion model. The study begins by mathematically representing the steganography tasks of paired images, introducing two optimization objectives: minimizing the secrecy leakage function and embedding distortion function. Subsequently, it identifies three key issues that need to be addressed in paired image steganography tasks and, through specific constraint mechanisms and optimization strategies, enables the diffusion model to effectively handle paired data. This enhances the quality of the generated stego-images and resolves issues such as image clarity. Finally, on public datasets like CelebA, the proposed model is compared with existing generation model-based image steganography techniques, analyzing its implementation effects and performance parameters. Experimental results indicate that, compared to current technologies, the model framework proposed in this study not only improves image quality but also achieves significant enhancements in multiple performance metrics, including the imperceptibility and anti-detection capabilities of the images. Specifically, the PSNR of its stego-images reaches 93.14dB, and the extracted images’ PSNR reaches 91.23dB, an approximate improvement of 30% over existing technologies; the attack success rate is reduced to 2.4x10-38. These experimental outcomes validate the efficacy and superiority of the method in image steganography tasks.

  • Understanding Fivefold Symmetry in Electron-Diffraction Patterns

    分类: 物理学 >> 凝聚态:结构、力学和热性能 提交时间: 2024-04-22

    摘要: Electron-diffraction patterns with5-fold rotational symmetry of experimental alloy phases are assumedto be produced by periodic structures. Two three-dimensionalperiodic structures are presented based on regular pentagonal dodecahedrons. These structures can be used as atomic models todescribe the alloy phases. The Fourier-transform patterns of themodels are found to be similar to the correspondingelectron-diffraction patterns of these alloy phases. Details of themotivations and approaches that lead to thesemodels are also discussed. 

  • Correction to the quantum relation of photons involved in the Doppler effect in the framework of a special Lorentz violation model

    分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2024-04-22

    摘要: In this paper we followed the idea in Ref. 1 to discuss the Doppler frequency shift of photons and the Compton scattering between photons and electrons, pointing out that followingthe idea we have to modify the usual quantum relation of massless particle. But due to limitedinformation and knowledge, we couldn’t yet determine the specific expression for the correctioncoefficient of the quantum relation of massless particle. However, the phenomenon of spontaneous radiation in a cyclotron maser give us an opportunity to see what the expression for this correctioncoefficient might look like, as the phenomenon of spontaneous radiation in a cyclotron maser canbe explained by the effect of Doppler frequency shift of virtual photons and Compton scatteringbetween virtual photons and electrons. Therefor, under some restrictive conditions, we construct a very concise expression for this correction coefficient by discussing different cases. And then we used this expression to analyze the wavelength of radiation in the cyclotron maser, which tends toa limited value at v→c, rather than to 0 as in the Lorentz model. This paper still inherits the idea inRef. 1 that the energy and momentum of particles cannot be infinite, otherwise it will make some equations meaningless, and this view is also from the idea in some quantum gravity models. This paper also provides us with a possible experimental scheme to determine the value of Qin Ref. 1 , but it still requires extremely high experimental energy.

  • Guiding Large Language Models to Generate Computer-Parsable Content

    分类: 计算机科学 >> 计算机科学技术其他学科 提交时间: 2024-04-21

    摘要: We propose a method to guide Large Language Models (LLMs) in generating structured content adhering to specific conventions without fine-tuning. By utilizing coroutine-based content generation constraints through a pre-agreed context-free grammar (CFG), LLMs are directed during decoding to produce formal language compliant outputs. This enhances stability and consistency in generating target data structures, types, or instructions, reducing application development complexities. Experimentally, error rates of GPT-2 and Gemma exceed 95% for DSLs longer than 36 and 282 tokens, respectively. We introduce YieldLang, a coroutine-based DSL generation framework, and evaluate it with LLMs on various tasks including JSON and Mermaid flowchart generation. Compared to benchmarks, our approach improves accuracy by 1.09 to 11.6 times, with LLMs requiring only about 16.5% of the samples to generate JSON effectively. This enhances usability of LLM-generated content for computer programs.

  • 引导大语言模型生成计算机可解析内容

    分类: 计算机科学 >> 计算机科学技术其他学科 提交时间: 2024-04-21

    摘要: 此幻灯片从背景、动机、方法、效果、展望和致谢六方面讲述了《引导大语言模型生成计算机可解析内容》的研究。全文请参考:https://arxiv.org/abs/2404.05499

  • 童年期创伤后亲子关系对青少年社会适应的影响:HPA轴系统多基因的调节

    分类: 心理学 >> 发展心理学 提交时间: 2024-04-21

    摘要: 童年期的不良经历似乎增加了个体对压力刺激的敏感性,从而可能影响其终身的社会适应。许多研究表明,HPA轴系统基因可能在调节环境因素与社会适应之间发挥作用。然而,过去单个基因与环境相互作用对社会适应的影响存在争议。本研究针对青少年样本(14.15 ± 0.63岁; N = 700),采用多位点遗传谱评分(multilocus genetic profile scores, MGPS)计算HPA轴系统多基因得分,利用纵向数据探究其与童年期创伤和亲子关系之间的相互作用,并预测青少年的社会适应(包括抑郁症状、亲社会行为和自伤行为)。研究结果显示,青少年的社会适应(包括抑郁症状和亲社会行为)是遗传(HPA轴系统MGPS)、远端环境(童年期创伤)和近端环境(亲子关系)三者相互作用的结果。随着遗传风险评分的增加,童年期创伤和亲子关系之间的交互作用也增加,这意味着遭受过童年期创伤的个体,亲子关系对社会适应的影响会更加显著,符合差别易感性模型。行为学实验进一步揭示了遗传和环境因素对青少年社会适应的潜在机制。

  • 我国数据要素研究进展:内涵阐释、价值释放、运行机理与治理体系

    分类: 图书馆学、情报学 >> 情报学 提交时间: 2024-04-21

    摘要: 目的/意义 作为新型生产要素的数据要素与其他要素一起共同构成全要素,为全球经济社会发展提供重要动力。数据要素是我国首次提出的重大理论创新,系统收集、梳理、剖析我国数据要素研究的代表性成果,构建中国特色的数据要素知识框架体系,为全球数据要素的理论研究及实践探索提供借鉴和启示。 方法/过程 主要采用网络调查、文献调研、内容分析法归纳我国数据要素研究的56篇具有代表性的文献内容、14份政策报告以及专家观点等,从内涵阐释、价值释放、运行机理与治理体系4个方面进行梳理和分析。 结果/结论 我国数据要素研究成果丰硕,知识框架体系基本形成,在价值实现与市场培育方面取得了一定进展,但在数据要素的有效运行以及数据要素治理方面仍具有较大提升空间,未来研究需要注重统筹推进数据要素治理体系建设并促进与应用场景的结合进而发挥乘数效用。

  • 行星摄动方程的非微扰修正

    分类: 天文学 >> 天体力学 分类: 物理学 >> 地球物理学、天文学和天体物理学 提交时间: 2024-04-20

    摘要: 本文简要介绍新的对称形式的质点动力学方程对天体动力学理论的系统性改进。 首先,对于开放的多体系统,无法找到近似程度非常高的惯性系,在传统理论中不得不引入惯性系的近似,而对称新方程因为可以直接适用于任意的平动参考系而避免了惯性系的近似,从而可以提高理论预言的精度。其次,对于束缚的多体系统,传统理论的动力学应用是先引入质心参考系,在质心参考系中应用牛顿第二定律,然后通过坐标变换再转化到实体参考系,比如太阳系的行星摄动方程。 但是,应用对称新方程则可以一步到位推导得到行星摄动方程。最后,如果进一步考虑行星受到临时推力或者冲击力,甚至为了进一步提高计算精度进而考虑来自束缚系统外的作用力,则一个可以叠加非微扰作用力的行星摄动的修正方程在本文得到了确立。

  • 1例针刺辅助鼻空肠置入成功患者的护理体会

    分类: 护理学 >> 护理学 提交时间: 2024-04-20

    摘要: 本文选取1例因家中经鼻胃管肠内喂养误吸引起的肺部感染患者,于我科住院后需更换为鼻空肠管进行肠内营养支持,由于患者脑梗后遗症,长期卧床,胃肠蠕动缓慢,经过两次置管失败后,通过积累经验及查阅文献,充分发挥中医技术的特色及优势,成功置管,后续给予患者营养支持,指标明显改善的案例。这一成功案例不仅证明了中西医结合治疗的有效性,也为置管方法提供了新的思路。现将病例记录如下。

  • 我的中国心:唤醒民族危机感与自豪感选择性增强后续记忆编码

    分类: 心理学 >> 实验心理学 分类: 心理学 >> 社会心理学 提交时间: 2024-04-20

    摘要: 情绪能够强化记忆编码且对后续记忆编码也有增强效果。本研究探索复杂社会情绪(即民族危机感和自豪感)唤醒如何影响后续的记忆编码。在问卷调查的基础上,研究利用两个实验探索民族情绪唤醒如何选择性地增强记忆编码。实验2采用被试间设计,参与者被随机分配到危机感、自豪感及中性情绪组进行情绪唤醒,随后进行记忆编码。结果显示,民族危机感和自豪感的唤醒显著增强了记忆编码,但对同一时间窗内与民族情绪无关图片记忆无显著影响。实验3采用相同的设计,但更换记忆材料为数学统计概念,结果发现民族情绪唤醒不影响数学统计记忆编码。本研究深化了我们对复杂社会情绪与记忆交互作用的理解,同时为优化高校思想政治教育提供了实证基础。

  • 公众与患者健康科普手册的编制与应用

    分类: 图书馆学、情报学 >> 图书馆学 提交时间: 2024-04-19

    摘要: 随着健康中国的深入推进,公众健康素养水平显著提高,患者越来越多地参与到共同决策中,健康科普手册为公众和患者提供了知情、选择和寻求支持的依据,在增强医疗过程中的信息对等、促进医患的有效沟通、降低患者疾病不确定感、帮助患者进行积极医学应对等方面发挥着重要作用,但如何制定健康科普手册,国内尚缺乏指导性意见。团队经过三年多的探索,形成了一套公众与患者健康科普手册编制流程和应用方法,普遍适用于健康行业从业人员和有志于从事健康科普创作的公众与患者,以期为健康科普工作的推进提供借鉴。

  • 面向多维度测量的硅像素探测器读出芯片IMPix-N1的设计

    分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2024-04-19

    摘要: 为满足高能物理实验对基本粒子检测和分析的需求,现代像素探测器研发日益趋向追求低功耗、高分辨率、高读出效率的性能要求。本文研究了一款名为IMPix-N1的硅像素探测器数模混合读出芯片,像素阵列由16行×16列像素单元构成,每个像素单元面积为100μm×100μm,像素阵列部分以1行×8列的像素单元为一个超级像素,其具有共同的逻辑电路进行控制。芯片具有像素配置模式和三种像素地址读出方式的工作模式,实现了对击中粒子时间、能量及位置信息的测量、存储及读出。时间数字转换电路(TDC)可以同时测量和记录粒子的到达时间 TOA 和过阈时间 TOT,时间测量精度为5ns。IMPix-N1适用于要求高时间、空间分辨率以及快速数据获取能力的粒子探测实验。在TSMC 180 nm工艺下,芯片整体使用digital-on-top的方法进行设计。本设计对像素单元数字电路、超级像素控制电路和外围数字电路进行仿真验证,前后仿真结果一致,满足设计要求。

  • 我国订单定向医学生履约、留任意愿率的Meta分析

    分类: 医学、药学 >> 医学、药学其他学科 提交时间: 2024-04-19 合作期刊: 《中国全科医学》

    摘要: 背景为改变基层全科医生数量不足的问题,我国从 2010 年开始实施农村订单定向医学生(简称订单生)培养项目,当前我国五年制本科订单生的整体履约意愿、履约情况、留任意愿仍不清楚,需要有更可靠证据的支持。目的系统评价我国本科订单生的履约意愿率、履约率、留任意愿率,并分析影响因素。方法于 2022 年 1—6 月,系统检索中国知网、万方数据知识服务平台、维普网、中国生物医学文献数据库、PubMed、Embase 数据库,以获取与我国订单生基层服务意愿、履约情况、留任意愿相关的文献,检索时限设定为 2010-01-01 至 2021-12-31,文献语种限定为中、英文。由 2 名研究员独立筛选文献并提取数据,评价纳入研究的偏倚风险。采用 RevMan 5.4 软件进行单组率的 Meta 分析。结果共纳入 49 篇文献,调查时间为 2010—2020 年,涉及 22 413 名订单生。订单生的履约意愿率为 62%[95%CI(55%~69%)],履约率为 95%[95%CI(93%~96%)],留任意愿率为 16%[95%CI(12%~19%)]。亚组分析结果显示,2011 年发表文献的履约意愿率[90%,95%CI(84%~96%)]高于其他年份发表的文献(P<0.01),华北地区的履约意愿率[87%,95%CI(84%~90%)]高于其他地区(P<0.01),在校学生的履约意愿率[68%,95%CI(67%~69%)]高于住院医师规范化培训(简称规培)生(P<0.01);2020 年发表文献的履约率[99%,95%CI(99%~100%)]高于其他年份发表文献(P<0.01),华中地区履约率[100%,95%CI(99%~100%)]高于其他地区(P<0.01);2015 年发表文献的留任意愿率[36%,95%CI(2%~70%)]高于其他年份发表文献(P<0.01),华南地区的留任意愿率[23%,95%CI(4%~41%)]高于其他地区(P<0.01),在校学生的留任意愿率[18%,95%CI(13%~22%)]高于规培生和基层服务生(P<0.01)。结论我国订单生的实际履约率较高,但履约意愿和留任意愿不高,地区、时间、所处医学教育阶段是影响因素。

  • Analysis of effects to scientific impact indicators based on the coevolution of coauthorship and citation networks

    分类: 图书馆学、情报学 >> 情报学 提交时间: 2024-04-19

    摘要: While computer modeling and simulation are crucial for understanding scientometrics, their practical use in literature remains somewhat limited. In this study, we establish a joint coauthorship and citation network using preferential attachment. As papers get published, we update the coauthorship network based on each paper’s author list, representing the collaborative team behind it. This team is formed considering the number of collaborations each author has, and we introduce new authors at a fixed probability, expanding the coauthorship network. Simultaneously, as each paper cites a specific number of references, we add an equivalent number of citations to the citation network upon publication. The likelihood of a paper being cited depends on its existing citations, fitness value, and age. Then we calculate the journal impact factor and h -index, using them as examples of scientific impact indicators. After thorough validation, we conduct case studies to analyze the impact of different parameters on the journal impact factor and h -index. The findings reveal that increasing the reference number N or reducing the paper’s lifetime θ significantly boosts the journal impact factor and average h -index. On the other hand, enlarging the team size m without introducing new authors or decreasing the probability of newcomers p notably increases the average h -index. In conclusion, it is evident that various parameters influence scientific impact indicators, and their interpretation can be manipulated by authors. Thus, exploring the impact of these parameters and continually refining scientific impact indicators are essential. The modeling and simulation method serves as a powerful tool in this ongoing process, and the model can be easily extended to include other scientific impact indicators and scenarios.

  • An improved analysis method for assessing the nuclear-heating impact on the stability of toroidalfield magnets in fusion reactors

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-04-19

    摘要: The superconducting magnet system of a fusion reactor plays a vital role in plasma confinement, a processthat can be disrupted by various operational factors. A critical parameter for evaluating the temperature marginof superconducting magnets during normal operation is the nuclear heating caused by D-T neutrons. This studyinvestigates the impact of nuclear heating on a superconducting magnet system by employing an improvedanalysis method that combines neutronics and thermal hydraulics.In the magnet system, toroidal field (TF) magnets are positioned closest to the plasma and bear the highestnuclear-heat load, making them prime candidates for evaluating the influence of nuclear heating on stability.To enhance the modeling accuracy and facilitate design modifications, a parametric TF model that incorporatesheterogeneity is established to expedite the optimization design process and enhance the accuracy of the computations. A comparative analysis with a homogeneous TF model reveals that the heterogeneous model improvesaccuracy by over 12%. Considering factors such as heat load, magnetic-field strength, and cooling conditions,the cooling circuit facing the most severe conditions is selected to calculate the temperature of the superconductor. This selection streamlines the workload associated with thermal-hydraulic analysis. This approach enablesa more efficient and precise evaluation of the temperature margin of TF magnets. Moreover, it offers insightsthat can guide the optimization of both the structure and cooling strategy of superconducting magnet systems.

  • 水罐疗法联合中药膏摩治疗1例肥胖患者腰椎间盘突出症的个案报告

    分类: 护理学 >> 护理学 提交时间: 2024-04-19

    摘要: 本文总结腰部水罐疗法联合腹部中药膏摩对1例肥胖患者腰椎间盘突出症疼痛程度及功能的影响,总结护理体会。运用水罐疗法的物理治疗效果和药物渗透治疗的生化效果,达到温通经络、活血化瘀的作用 1 ,缓解患者腰部疼痛症状。同时联合腹部中药膏摩以调节气血、疏通经络,加快胃肠蠕动 2 ,改善便秘症状。促进体重降低,减少肥胖加速腰椎退变的风险,减少腰部机械负荷过重造成的疼痛 3 。治疗期间,给予饮食护理、心理护理、功能锻炼等相关指导,帮助患者控制疼痛、停用止痛药,恢复行走功能,回归正常生活。

  • 腰椎运动链训练系统对腰椎间盘突出症患者术后腰椎功能与生物力学的影响

    分类: 力学 >> 生物力学 提交时间: 2024-04-19 合作期刊: 《应用力学学报》

    摘要: 探讨腰椎运动链训练系统对腰椎间盘突出症(lumbar disc herniation,LDH)术后腰椎功能与生物力学的影响。通过选取河南省信阳市中心医院收治的122例LDH患者,随机数字表法分组,各61例。两组均行手术治疗,对照组采取常规训练,观察组基于对照组采取腰椎运动链训练系统。比较2组干预效果。干预12周后、24周后观察组健侧、弱链侧平均振幅值、步幅、步频、腰背伸展状态平均功率(AP)、腰背伸展状态平均功率(PT)高于对照组,VAS评分及腰背屈/伸比(F/E)低于对照组(P<0.05); 干预24周后观察组SF-36、BI评分高于对照组(P<0.05)。腰椎运动链训练系统可缓解LDH术后疼痛,改善下肢步态,恢复腰椎功能及生物力学,提高生活质量。

  • 基于双向流固耦合的倒虹吸管道水击压力波与拱式桥架组合结构动力响应分析

    分类: 力学 >> 流体力学 提交时间: 2024-04-19 合作期刊: 《应用力学学报》

    摘要: 在大跨度倒虹吸管道中有压闸阀关闭时通常伴随着水击现象,当水击发生时,流体与固体的耦合作用同时存在。为研究发生水击时,不同关阀时间下的压力波与考虑耦合作用时结构的动力响应情况,以大跨度倒虹吸管道与拱式桥架结构为研究对象,进行整体水力计算,基于流固耦合分析理论,将整体水力模型计算得到的水击压力波作为流体部分加载条件,在workbench平台上进行双向流固耦合分析求解桥架结构的位移、内力及应力动力响应结果。结果表明:不同关阀时间工况下,水击压力波曲线的变化趋势大致相同,结构各监测点的位移时程曲线同水击压力波曲线规律基本吻合; 阀门匀速关闭时,增加闸阀的关闭时间可以作为降低倒虹吸管道水击压强的有效措施; 水击力对桥架管道的影响最大,盖梁次之,拱圈最小,结构以发生顺桥向动力响应为主。

  • 新型装配式梁柱节点有限元参数分析

    分类: 力学 >> 力学其他学科 提交时间: 2024-04-19 合作期刊: 《应用力学学报》

    摘要: 提出了一种装配式梁柱节点新形式,带悬臂梁段的框架柱与框架梁进行拼接,通过L形角钢进行节点加强,形成全螺栓装配式节点。为研究该节点的力学性能,以前期试验作为研究基础,对带悬臂梁段拼接的装配式新型梁柱节点采用ABAQUS软件进行参数分析。首先建立装配式梁柱节点的足尺试验模型,与试验结果进行对比验证; 然后,对带悬臂梁段拼接节点进行参数化分析并且考虑加劲肋数量、横板厚度、耳板厚度、L形角钢长度和翼缘螺栓数量的因素,得到不同参数下节点的力学性能。