检索结果-南通市图书馆

基于希尔伯特空间曲线填充的太赫兹图像超分辨算法研究

在线全文

学校读者我要写书评

暂无评论

红外与毫米波学报 2024年第4期43卷 541-550页

作者：杨墨轩赵源萌刘昊鑫刘祎吴悠张存林太赫兹光电子学教育部重点实验室北京100048 太赫兹波谱与成像北京市重点实验室北京100048 北京成像理论与技术高精尖创新中心北京100048 首都师范大学物理系北京100048

太赫兹成像技术受辐射源和探测器性能限制,在细节分辨能力、成像速度和噪声抑制等方面仍有进一步改进的空间。本文提出一种基于空间曲线填充的太赫兹图像超分辨算法,采用视觉自注意力(Vision Transformer,ViT)结构主干网络,通过注意力... 详细信息

太赫兹成像技术受辐射源和探测器性能限制,在细节分辨能力、成像速度和噪声抑制等方面仍有进一步改进的空间。本文提出一种基于空间曲线填充的太赫兹图像超分辨算法,采用视觉自注意力(Vision Transformer,ViT)结构主干网络,通过注意力机制进行太赫兹图像特征提取;构建希尔伯特空间曲线,根据特征图按曲线填充的方式进行图像重建,并用轻量化的一维卷积处理重建图像特征,对重建图进行逆变换恢复图像空间结构;最终通过像素重组实现上采样,得到物体轮廓和细节增强的输出图像。实验表明,相较常规ViT结构,本文方法图像峰值信噪比(PSNR)提高0.81 dB,结构相似度(SSIM)提高0.0074,有效抑制了噪声对图像纹理的影响,获得了分辨能力显著提高的结果图像,证明了太赫兹图像超分辨处理技术的可行性及其恢复图像细节、提高图像质量的能力。

关键词：太赫兹成像超分辨重建注意力机制空间曲线

多孔中药固体片剂孔隙率的太赫兹有效介质模型研究

在线全文

学校读者我要写书评

暂无评论

红外与毫米波学报 2024年第3期43卷 344-353页

作者：李旭张梦圆赵雯玥左剑朱卫丰李哲施宇蕾张存林首都师范大学物理系太赫兹光电子学教育部重点实验室北京100048 江西中医药大学现代中药制剂教育部重点实验室江西南昌330004

目前对中药片剂的孔隙测量,一般采用的是具有破坏性的密度测量方法,缺乏无损量化方法。太赫兹辐射能用于无损的提取药物若干光学信息。针对直压型中药片剂,通过太赫兹时域和频域信号处理等不同方法分别计算各种片剂的有效折射率,发现两... 详细信息

目前对中药片剂的孔隙测量,一般采用的是具有破坏性的密度测量方法,缺乏无损量化方法。太赫兹辐射能用于无损的提取药物若干光学信息。针对直压型中药片剂,通过太赫兹时域和频域信号处理等不同方法分别计算各种片剂的有效折射率,发现两种方法得到的有效折射率和片剂的孔隙率均呈良好的线性关系。根据有效折射率特性,利用四种有效介质模型提取了中药片剂的孔隙率并进行量化回归,通过交叉验证与相对分析误差(RPD)发现通过时域信号处理的有效折射率得到的孔隙率回归模型解释性与验证准确性更高,其中最佳模型是Bruggeman模型(RPD=11.3325)。为中药多孔粉体制剂工艺优化提供支持。

关键词：太赫兹光谱有效折射率有效介质理论中药片剂孔隙率

Quantum Computation with Nonlinear Optics

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2008年第1期49卷 107-110页

作者： LIU Yang zhang Wen-Hong zhang cun-lin LONG Gui-Lu Key Laboratory of Atomic and Molecular NanoSciences and Department of Physics Tsinghua University Beijing 100084China Department of Physics Capital Normal University Beijing 100037 China Tsinghua National Laboratory for Information Science and Technology Beijing 100084 China

We propose a scheme of quantum computation with nonlinear quantum optics. Polarization states of photons are used for qubits. Photons with different frequencies represent different qubits. Single qubit rotation operation is implemented through optical elements like the Faraday polarization rotator. Photons are separated into different optical paths, or merged into a single optical path using dichromatic mirrors. The controlled-NOT gate between two qubits is implemented by the proper combination of parametric up and down conversions. This scheme has the following features：（1） No auxiliary qubits are required in the controlled-NOT gate operation; （2） No measurement is required in the course of the computation; （3） It is resource efficient and conceptually simple.

关键词： quantum computation nonlinear optics parametric up(down)-conversion polarization modulator

Quantitative Analysis for Monitoring Formulation of Lubricating Oil Using Terahertz Time-Domain Transmission Spectroscopy

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2012年第4期29卷 68-70页

作者： TIAN Lu ZHAO Kun ZHOU Qing-Li SHI Yu-Lei zhang cun-lin State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing 102249 Laboratory of Optic Sensing and Detecting Technology China University of PetroleumBeijing 102249 International Center for Materials Physics Chinese Academy of SciencesShenyang 110016 Beijing Key Laboratory for Terahertz Spectroscopy and Imaging Key Laboratory of Terahertz Optoelectronics(Ministry of Education)Department of PhysicsCapital Normal UniversityBeijing 100048

The quantitative analysis of zinc isopropyl-isooctyl-dithiophosphate (T204) mixed with lube base oil from Korea with viscosity index 70 (T204-Korea70) is presented by using terahertz time-domain spectroscopy (THz-TDS).Compared with the middle-infrared spectra of zinc n-butyl-isooctyl-dithiophosphate (T202) and T204,THz spectra of T202 and T204 show the weak broad absorption ***,the absorption coefficients of the T204-Korea70 system follow Beer's law at the concentration from 0.124 to 4.024%.The experimental absorption spectra of T204-Korea70 agree with the calculated ones based on the standard absorption coefficients of T204 and *** quantitative analysis enables a strategy to monitor the formulation of lubricating oil in real time.

关键词： absorption spectra enable

Probing PM_(2.5) with terahertz wave

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2014年第12期57卷 2354-2356页

作者： LI Qian ZHAO Kun zhang Lei Wei LIANG Chuan zhang Zhen Wei zhang cun lin HAN Dong Hai State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum Key Laboratory of Oil and Gas Terahertz Spectroscopy and Photoelectric Detection China Petroleum and Chemical Industry Federation (CPCIF) Beijing Key Laboratory of Optical Detection Technology for Oil and Gas China University of Petroleum Department of Physics Capital Normal University College of Food Science and Nutritional Engineering China Agricultural University

The goal of continuous ambient participate monitoring has been accomplished by the use of terahertz （THz） wave. The fre- quency-dependent spectrum and absorbance of the particulate matter （PM2.5） were measured in the range of 0-10 THz. The PM2.5 concentration ,o was calculated according to the sampling time and air flow. With the increase of ,o, the THz wave am- plitude gradually decreased and the absorbance A of PM2.5 increased. The relationship between p and A can be described mathematically through p∝ A0.5. Our results demonstrate that the terahertz wave could be a valuable tool to monitor and in- spect the PM2.5 concentration.

关键词： PM2.5 terahertz concentration absorbance

A fast forward computational method for nuclear measurement using volumetric detection constraints

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2024年第2期35卷 47-63页

作者： Qiong zhang lin-Lv lin University of Electronic Science and Technology of China Chengdu 610000China

Owing to the complex lithology of unconventional reservoirs,field interpreters usually need to provide a basis for interpretation using logging simulation *** the various detection tools that use nuclear sources,the detector response can reflect various types of information of the *** Monte Carlo method is one of the primary methods used to obtain nuclear detection responses in complex ***,this requires a computational process with extensive random sampling,consumes considerable resources,and does not provide real-time response ***,a novel fast forward computational method(FFCM)for nuclear measurement that uses volumetric detection constraints to rapidly calculate the detector response in various complex environments is ***,the data library required for the FFCM is built by collecting the detection volume,detector counts,and flux sensitivity functions through a Monte Carlo ***,based on perturbation theory and the Rytov approximation,a model for the detector response is derived using the flux sensitivity function method and a one-group diffusion *** environmental perturbation is constrained to optimize the model according to the tool structure and the impact of the formation and borehole within the effective detection ***,the method is applied to a neutron porosity tool for *** various complex simulation environments,the maximum relative error between the calculated porosity results of Monte Carlo and FFCM was 6.80%,with a rootmean-square error of 0.62 *** field well applications,the formation porosity model obtained using FFCM was in good agreement with the model obtained by interpreters,which demonstrates the validity and accuracy of the proposed method.

关键词： Nuclear measurement Fast forward computation Volumetric constraints

Degradation and biocompatibility of one-step electrodeposited magnesium thioctic acid/magnesium hydroxide hybrid coatings on ZE21B alloys for cardiovascular stents

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2024年第1期12卷 120-138页

作者： Zhao-Qi zhang Bing-Zhi Li Pei-Duo Tong Shao-Kang Guan Li Wang Zheng-Hui Qiu cun-Guo lin Rong-Chang Zeng School of Material Science and Engineering&Henan Key Laboratory of Advanced Magnesium Alloy&Key Laboratory of Materials Processing and Mold Technology(Ministry of Education) Zhengzhou University100 Science RoadZhengzhou 450001China State Key Laboratory for Marine Corrosion and Protection Luoyang Ship Material Research InstituteQingdao 266101China Corrosion Laboratory for Light Metals College of Material Science and EngineeringShandong University of Science and TechnologyQingdao 266590China

Constructing a functional hybrid coating appears to be a promising strategy for addressing the poor corrosion resistance and insufficient endothelialization of Mg-based ***,the steps for preparing composite coatings are usually complicated and ***,a novel composite coating,composed of bioactive magnesium thioctic acid(MTA)layer formed by deposition and corrosion-resistant magnesium hydroxide(Mg(OH)_(2))layer grown in situ,is simply fabricated on ZE21B alloys via one-step *** electron microscopy(SEM)shows that the electrodeposited coating has a compact and uniform *** the high adhesion of the MTA/Mg(OH)_(2)hybrid coating is also confirmed by the micro-scratch *** test,scanning kelvin probe(SKP),and hydrogen evolution measurement indicate that the hybrid coating effectively reduces the degradation rate of Mg *** experiment and cell culture trial detect that the composite coating is of fine ***,the preparation mechanism of MTA/Mg(OH)_(2)hybrid coatings is discussed and *** coating shows a great potential application for cardiovascular stents.

关键词： Magnesium alloy Corrosion resistance Hybrid coating Endothelialization Biocompatibility

Indispensable gutter layers in thin-film composite membranes for carbon capture

在线全文

学校读者我要写书评

暂无评论

Green Energy & Environment 2024年第8期9卷 1220-1238页

作者： Gengyi zhang Haiqing lin Department of Chemical and Biological Engineering University at Buffalo The State University at New York

Industrial thin-film composite(TFC) membranes achieve superior gas separation properties from high-performance selective layer materials,while the success of membrane technology relies on high-performance gutter layers to achieve production scalability and low-cost manufacturing. However, the current literature predominantly focuses on the design of polymer architectures to obtain high permeability and selectivity, while the art of fabricating gutter layers is usually safeguarded by industrial manufacturers and appears lackluster to academic researchers. This is the first report aiming to provide a comprehensive and critical review of state-of-the-art gutter layer materials and their design and modification to enable TFC membranes with superior separation performance. We first elucidate the importance of the gutter layer on membrane performance through modeling and experimental results. Then various gutter layer materials used to obtain high-performance composite membranes are critically reviewed, and the strategies to improve their compatibility with the selective layer are highlighted, such as oxygen plasma treatment, polydopamine deposition, and surface grafting. Finally, we present the opportunities of the gutter layer design for practical applications.

关键词： Thin-film composite membranes Gutter layer Gas separation Carbon capture

Hydrodynamic Characteristics of Undular Tidal Bores in the Qiantang River Based on Field Observations

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

China Ocean Engineering 2024年第3期38卷 505-518页

作者： zhang Shu-yu PAN cun-hong zhang Shen-yang LI Ruo-hua CHENG Wenlong XIE Dong-feng Zhejiang Tongji Vocational College of Science and Technology Hangzhou 311231China Zhejiang Institute of Hydraulics and Estuary Hangzhou 310020China

Understanding the undular tidal bores in the Qiantang River is essential for effective river management and *** breaking tidal bores have been studied extensively, reports on undular tidal bores in the Qiantang Riverremain limited. Furthermore, observed data on undular tidal bores fulfilling the requirements of short measurementtime intervals, and spring, medium, and neap tide coverage, and providing detailed data for the global vertical stratificationof flow velocity are quite limited. Based on field observations at Qige in the Qiantang estuary, we analyzedthe characteristics of undular tidal bores. The results showed that the flooding amplitude (a) of the first wave isalways larger than its ebbing amplitude (b). Moreover, the vertical distribution of the maximum flood velocity exhibitesthree shapes, influenced by the tidal range, while that of the maximum ebb velocity exhibites a single shape. Duringthe initial phase of the flood tide in the spring and medium tides, the upper water body experiences multiple oscillatingchanges along the flow direction, corresponding to the alternating process of the crest and trough of the tide levelupon the arrival of the tidal bore. The tidal range is a crucial parameter in tidal bore hydrodynamics. By establishingthe relationship between hydrodynamic parameters and tidal range, other hydrodynamic parameters, such as the tidalbore height, maximum flood depth–averaged velocity, maximum flood stratified velocity at the measurement points,and duration of the flood tide current, can be effectively predicted, thereby providing an important reference for rivermanagement and maintenance.

关键词： tidal bores Qiantang Estuary tidal bore height tidal bore velocity propagation speed