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： 2023-12-03
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： 工程与技术科学 >> 工程与技术科学其他学科 提交时间： 2023-11-10 合作期刊: 《应用力学学报》
摘要：纳米材料可有效改善水泥基的力学性能和耐久性,为探索纳米SiO2、Fe2O3对混凝土材料的增强机理,研制力学性能更优的混凝土,制备了0%～2.0%掺量范围内单掺纳米SiO2、纳米Fe2O3、复掺纳米SiO2和纳米Fe2O3的混凝土试件,对养护龄期为7 d及28 d的混凝土力学性能开展试验研究,结果表明:纳米材料总掺量为1.5%且纳米SiO2掺量为1.0%、纳米Fe2O3掺量为0.5%时改性混凝土的力学性能达到最优,该复掺比例改性混凝土比普通混凝土及同掺量的单掺改性混凝土具有更优异的力学性能。采用冷场发射扫描电镜对纳米改性混凝土内部微观形貌进行观察,并借助能量分散谱仪分析纳米改性混凝土的化学成分,结果表明掺入的纳米SiO2及纳米Fe2O3会发生晶核作用并与Ca(OH)2晶粒发生化学反应,在混凝土内部分别生成珊瑚状、球状水化产物C-S-H凝胶及C-F-H凝胶,晶核的高活性吸附凝胶在其表面聚集,减少Ca(OH)2晶粒的数量,并互补填充形成密实的水化产物,使混凝土结构更加紧实致密。研究成果可为高性能混凝土的研发提供参考。
分类： 工程与技术科学 >> 工程与技术科学其他学科 提交时间： 2023-11-10 合作期刊: 《应用力学学报》
摘要：基于层合板壳理论,考虑反对称铺设层合板的拉弯耦合效应和后屈曲过程中的非线性几何变形,推导了由应力函数和挠度表示的复合材料层合板的后屈曲控制方程。引入无量纲参数对控制方程和边界条件进行无量纲化,以消除材料参数及几何尺寸对分析结果的影响。采用摄动法将无量纲的非线性控制方程及边界条件展开成一系列非齐次线性摄动方程组,分析各阶摄动方程的通解与特解的构造,并逐次求解,建立了反对称铺设复合材料层合板受单向均布压力作用的临界屈曲荷载及后屈曲平衡路径的理论解。进而运用ABAQUS软件对复合材料层合板在面内压缩载荷作用下的屈曲和后屈曲进行有限元分析,结果表明理论解与ABAQUS结果十分接近,验证了理论解的正确性。在此基础上进一步讨论了铺设角度、铺设层数和拉弯耦合效应等对层合板后屈曲性能的影响。研究发现层合板的屈曲载荷受铺设角度与层数的影响较为显著,而拉弯耦合效应使板的屈后强度大大降低。
分类： 工程与技术科学 >> 工程与技术科学其他学科 提交时间： 2023-11-10 合作期刊: 《应用力学学报》
摘要：采用大涡模拟(LES)和声比拟(AA)结合的方法,在低马赫数条件下,对SD7003多孔翼型自噪声声场进行计算,研究多孔材料在不同来流迎角下对翼型自噪声远场声压的影响规律,并阐述噪声的影响机理。结果表明:LES与AA相结合的方法能够较为准确地计算多孔翼型的边界层特征以及远场声压,且数值模拟结果与实验结果非常吻合。来流迎角为0°时,多孔翼型整体声压级随着渗透率的减小先减小后增大,渗透率为5×10-11 m2时多孔材料的降噪效果最佳。多孔翼型整体声压级随着迎角的增大而增大,但多孔材料的降噪效果随着迎角的增大而减小。多孔材料的存在能够有效地削弱翼型表面的大尺度相干结构,使得翼型表面的RMS压强脉动峰值减小,从而抑制翼型远场噪声。
分类： 工程与技术科学 >> 工程与技术科学其他学科 提交时间： 2023-11-10 合作期刊: 《应用力学学报》
摘要：民用飞机复材壁板与金属壁板的连接是机身结构设计的重要研究内容,如何将复材帽形长桁和金属Z形/2形长桁连接是研究的重点和难点。本研究提出了一种新型混合连接结构,同时考虑了预埋缺陷和BVID损伤对试验件的影响。通过试验、数值仿真等分析方法研究了混合连接结构的静强度特性,详细分析了试验件的受力情况、失效模式以及破坏位置,很好的解决了复材帽形长桁和金属Z形/2形长桁连接载荷传递问题。研究结果表明:该混合连接结构满足民用飞机结构与强度的设计要求,预埋缺陷和BVID损伤对试验件的破坏载荷和破坏模式无影响。以上研究结果为型号飞机的研制和发展提供重要的指导作用。
分类： 工程与技术科学 >> 工程与技术科学其他学科 提交时间： 2023-11-10 合作期刊: 《应用力学学报》
摘要：隔振平台连接直升机机体与光电跟瞄吊舱,对机载跟瞄系统的跟瞄精度至关重要。采用多个笼形隔振器并联,设计了一种直升机机载跟瞄系统的被动隔振平台。由欧拉变换描述隔振平台的空间姿态,基于Lagrange方法建立隔振平台的动力学模型,获得了不同激振频率下隔振平台的振动传递率。利用ANSYS动力学仿真验证了隔振平台理论模型的正确性,校核了大过载情况下隔振平台的冗余保护能力。通过实际飞行测试,检验了隔振平台的隔振效果。
分类： 工程与技术科学 >> 工程与技术科学其他学科 提交时间： 2023-09-05
摘要：This paper presents an overview of the theories and computer implementation aspects of phase field models (PFM) of fracture. The advantage of PFM over discontinuous approaches to fracture is that PFM can elegantly simulate complicated fracture processes including fracture initiation, propagation, coalescence, and branching by using only a scalar field, the phase field. In addition, fracture is a natural outcome of the simulation and obtained through the solution of an additional differential equation related to the phase field. No extra fracture criteria are needed and an explicit representation of a crack surface as well as complex track crack procedures are avoided in PFM for fracture, which in turn dramatically facilitates the implementation. The PFM is thermodynamically consistent and can be easily extended to multi-physics problem by 'changing' the energy functional accordingly. Besides an overview of different PFMs, we also present comparative numerical benchmark examples to show the capability of PFMs.
分类： 工程与技术科学 >> 生物医学工程学 提交时间： 2023-05-27
Wang, Dongping
Jin, Kai
Hu, Chenxuan
Du, Maohua
Belgaid, Yacine
Shi, Subao
Li, Jiahao
Hu, Siyi
Yu, Jun
Nathan, Arokia
Ma, Hanbin
摘要：Digital liquid sample handling is an enabling tool for cutting-edge lifesciences research. Similar to Field Programmable Gate Arrays (FPGA) in Integrated Circuits, we present here an active-matrix thin-film electronicsbased digital microfluidics system, which will be henceforth referred to as Field Programmable Droplets Arrays (FPDA). The system contains 256 × 256 pixels in an active area of 10.65 cm2, which is capable of manipulating thousands of individually addressable liquid droplets simultaneously. By leveraging a customised TFT-based circuit design solution, it becomes possible to programmatically manipulate droplets at the pixel level. The minimum achievable droplet volume is around 0.5 nl, which is two orders of magnitude smaller than the state-of-the-art reported1. The movement of droplets can be either pre-programmed or controlled in real-time. The FPDA system shows great potential of the ubiquitous thin-film electronics technology in digital liquid handling. These efforts will make it possible to create a true programmable lab-on-a-chip device to enable great advances in life science research.
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 GΩ, 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 μV/°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 >> 工程水文学 提交时间： 2023-03-30
摘要：为解决鱼洞河流域废弃煤矿酸性废水外排的问题，针对废弃煤矿酸性废水的成因（煤系地层硫化物、氧化环境、地下水及通道）及废弃煤矿的不同开采情况，分类施策、分部实施，通过对多处废弃煤矿治理经验的总结，提出了一套相对适合该区域实际情况的“追、堵、截、围”的煤矿废水“成因－源头式生态关水污水治理法”，即追索废弃煤矿的巷道分布、封堵关键段、截流地表水、采用帷幕灌浆抬升采空区的水位。该方法的基本原理是改变地表水进入采空区后直接外流的路径，采用巷道封堵、帷幕灌浆等手段隔绝废弃煤矿采空区的氧气，同时抬升地下水位，使顶板含水层逐步恢复到原有状态、使煤矿废水变成深部滞留水、使后续补给水从高位流出。雨季检验结果表明治理效果显著。
分类： 工程与技术科学 >> 工程地质学 提交时间： 2023-03-15
摘要：循环荷载作用下深厚饱和软黏土的固结与长期沉降变形分析对公路、地铁等基础设施的沉降分析有很重要的意义。传统的固结分析方法无法合理地考虑到长期循环荷载作用下软黏土的蠕变沉降，而基于弹粘塑性的本构模型分析又不能考虑长期循环荷载作用下土体固结过程中渗透系数kv和体积压缩系数mv的非线性变化。本文将综合考虑长期循环荷载作用下饱和软黏土的非线性固结及其固结过程中产生的蠕变。本文构建了一种具有普遍适用性的一维弹黏塑性非线性固结模型，可以较好的计算长期循环荷载作用下考虑蠕变效应的饱和软黏土的长期沉降变形。本文与土工试验相结合，给出了便于应用的模型参数确定方法；并提出了一种多级加载过程中的初始条件确定方法，该方法可以反映出应变和超静孔压在深度上的不均匀性。采用杭州软黏土进行了多组不同振幅不同频率不同动态偏移量的循环荷载固结试验，通过计算结果与试验结果的对比分析，验证了模型的合理性。
分类： 工程与技术科学 >> 工程力学 提交时间： 2023-02-24
摘要：对变压器励磁涌流和故障电流波形整体形态的特征进行分析，利用两者之间相似度差异，结合Hausdorff距离算法在图形相似度方面的优势，构造基于Hausdorff距离算法的变压器差动保护新判据，该判据采用标幺化后的差流序列和标准正弦波序列之间的Hausdorff距离值进行判别，以区分变压器的励磁涌流（包括对称性涌流）和故障差流（包括故障电流叠加励磁涌流）。通过仿真试验验证所提新判据的有效性、快速性和抗干扰性
分类： 工程与技术科学 >> 工程与技术科学其他学科 提交时间： 2023-01-10 合作期刊: 《Art & Design Research》
摘要：Cultural confidence is one of the important factors to promote the inheritance and development of excellent national culture. Maonan traditional craft contains excellent national culture, cultural customs and so on, which is a part of carrying forward China's traditional culture confidence. From the perspective of cultural confidence, this paper analyzes the characteristics and advantages of the current Maonan traditional crafts and puts forward suggestions to promote the innovative development of Maonan traditional crafts, which can better promote the inheritance and development of Maonan traditional crafts.
分类： 工程与技术科学 >> 工程与技术科学其他学科 提交时间： 2023-01-10 合作期刊: 《Art & Design Research》
摘要：Driven by the rapid development of omnimedia, the Internet, movies, television, etc. have gradually blend in people’s daily lives, and cartoons are also deeply loved by children. Colleges and universities are an important base for cultivating animation talents, in the process of carrying out animation teaching, due to the short setting up time and other reasons, it is necessary to continuously improve the teaching system of animation professional courses, and comprehensively analyze the current problems in teaching, so as to provide more help for students’ learning and avoid being affected by a variety of factors that lead to the inability to effectively improve teaching efficiency. In the language environment of omnimedia, it is necessary to actively improve the efficiency of animation teaching, optimize the teaching system according to the actual situation, and implement the teaching of all links to maximize the role of curriculum system reform. Based on this, this paper mainly analyzes the importance and necessity of animation curriculum reform in the language environment of omnimedia.
分类： 工程与技术科学 >> 工程与技术科学其他学科 提交时间： 2023-01-10 合作期刊: 《Art & Design Research》
摘要：Traditional dwellings with high regional artistic expression, is an important carrier of China's national culture, regional characteristics, ethnic customs. The wooden architecture of the Dong Nationality 's residential houses originated from the southern stilt-style architecture. Its unique construction technology is a treasure of national culture. Studying the aesthetic implication of Dong residential buildings will help people understand Dong culture more deeply. From the perspective of artistic aesthetics, this paper makes a detailed study of the dwellings of Dong people from five aspects: the environmental beauty of man-nature harmony, the beauty of building materials, the beauty of structure, the beauty of architectural skills and the beauty of culture. Hope to help readers understand the spiritual core of Dong culture, to better protect the Dong residential buildings wooden.
分类： 工程与技术科学 >> 工程与技术科学其他学科 提交时间： 2023-01-10 合作期刊: 《Art & Design Research》
摘要：In the past 30 years, the development of brownland into green land has become an important way for the sustainable development and management of urban land. Fully understanding the various application scenarios and values of this approach is helpful to explore its efforts in providing ecosystem services and meet the development needs of different types of cities. This paper reviews the practice and literature of brownfield redevelopment from the perspective of landscape architecture, and obtains the process of its theoretical development and its understanding deepening. Through sorting out the relevant discipline literature, the seven main green space types and their potential broad benefits are summarized, and we realize that the brownfield itself has many values that cannot be ignored in the development process. On this basis, it proposes that there is a new cognition of the relationship between brownfield and green space.
分类： 工程与技术科学 >> 工程与技术科学其他学科 提交时间： 2023-01-10 合作期刊: 《Art & Design Research》
摘要：In the post-epidemic era, great turbulence has taken place in the field of human life, especially the travel rate of people has been greatly reduced, but the requirements for urban public space required for travel are constantly improving.As the main social life space carrier of street space requires carrying more functions to meet the requirements of the outbreak era.Through literature search and social investigation, the optimization design strategy is proposed for the problems of weak slow traffic use right, monotonous space function, lack of commercial management, and random public facilities of urban streets. Then, through the legend analysis, the optimization effect of street space in four levels of environmental comfort, functional diversification, management order and facilities refine#2;ment can be achieved to improve the residents' street life experience and return to the public space essence of "people-oriented" street.
分类： 工程与技术科学 >> 工程与技术科学其他学科 提交时间： 2023-01-03 合作期刊: 《2022年第三届艺术设计、传播与工程科学研讨会》
摘要：With the change in media technology, the pattern of time and space is constantly broken, and the development of media tends to be more and more spatial and temporal freedom. On the social level, the social range of the general public is expanding, and the social distance is shrinking based on the expansion. However, people's senses have also changed, from balance to breaking balance to the constant pursuit of balance. In this paper, we will discuss the body logic of social networks and the future development trend of social networks from the perspective of senses based on the change of senses in the media.
分类： 工程与技术科学 >> 工程与技术科学其他学科 提交时间： 2023-01-03 合作期刊: 《2022年第三届艺术设计、传播与工程科学研讨会》
摘要：In order to explore the cultural connotation and artistic characteristics of Tang Dynasty ceramic decorative patterns, integrate traditional ethnic decorative patterns with modern design, and promote the inheritance and development of excellent traditional culture, this paper first understands the decorative patterns of Tang Dynasty ceramics by reading books and consulting materials, collects representative ceramic utensils of the Tang Dynasty, and extracts the decorative patterns on these cultural relics, analyzes the inner meaning of the patterns through semiotics, and understands their aesthetic characteristics. The use of shape grammar, complexity into simplicity, decomposition and reconstruction of the extracted pattern for innovative design, into the modern aesthetic concept, according to its semantic and visual characteristics into the modern product design and decoration. The Tang Dynasty is a representative period of China's culture, and the combination of Tang Dynasty patterns and modern design is conducive to inheriting the excellent culture of the Tang Dynasty, while increasing the cultural value of modern design and enhancing product competitiveness.
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