期刊文献+
共找到103篇文章
< 1 2 6 >
每页显示 20 50 100
Sequential transcatheter arterial chemoembolization,three-dimensional conformal radiotherapy,and high-intensity focused ultrasound treatment for unresectable hepatocellular carcinoma patients 被引量:9
1
作者 Shengfa Ni Lingxiang Liu Yongqian Shu 《The Journal of Biomedical Research》 CAS 2012年第4期260-267,共8页
The purpose of this study was to evaluate the outcome of patients with unresectable hepatocellular carcinoma(HCC) treated by sequential therapy of transcatheter arterial chemoembolization(TACE),three-dimensional c... The purpose of this study was to evaluate the outcome of patients with unresectable hepatocellular carcinoma(HCC) treated by sequential therapy of transcatheter arterial chemoembolization(TACE),three-dimensional conformal radiotherapy(3-DCRT) and high-intensity focused ultrasound(HIFU).From October,2005 to September,2010,120 patients with unresectable HCC received the sequential treatments of several courses of TACE followed in 2-4 weeks by 3-DCRT and then a single session of HIFU with a curative intent.The median tumor irradiation dose was 40 Gy.Tumor response,toxicity and overall survival rate were analyzed.Clinicopathologic factors affecting the primary technique effectiveness and overall survival rates were investigated by univariate analysis or multivariate analysis.All 120 HCC patients were followed up by the last follow-up time.Among these patients,hepatic toxicities due to treatment were notable in 9 cases.Gastrointestinal bleeding after the overall treatment occurred in 2 cases,leukopenia of grade III was detected in 1 case,radiation-induced liver disease(RILD) was observed in 2 patients,and first-and second-degree skin burn around the HIFU treatment zone were observed in 2 patients and 1 patient,respectively.Among 120 patients,23,83 and 14 cases achieved partial response,stable disease and progressive disease,respectively.The overall survival rates at 1 year,3 years and 5 years were 70%,35% and 15%,respectively,with a median survival time of 26 months.Both Child-Pugh liver function grading and radiation dose were determined to be independent predictors for overall survival revealed by the multivariate analysis.It is concluded that the sequential therapy of TACE,3-DCRT and HIFU is a promising therapeutic regimen for unresectable HCC. 展开更多
关键词 transcatheter arterial chemoembolization(TACE) three-dimensional con-formal radiotherapy(3DCRT) high-intensity focused ultrasound(HIFU) hepatocellular carcinoma
下载PDF
Three-dimensional vertical ZnO transistors with suspended top electrodes fabricated by focused ion beam technology
2
作者 Chi Sun Linyuan Zhao +4 位作者 Tingting Hao Renrong Liang Haitao Ye Junjie Li Changzhi Gu 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第1期492-496,共5页
Three-dimensional(3D)vertical architecture transistors represent an important technological pursuit,which have distinct advantages in device integration density,operation speed,and power consumption.However,the fabric... Three-dimensional(3D)vertical architecture transistors represent an important technological pursuit,which have distinct advantages in device integration density,operation speed,and power consumption.However,the fabrication processes of such 3D devices are complex,especially in the interconnection of electrodes.In this paper,we present a novel method which combines suspended electrodes and focused ion beam(FIB)technology to greatly simplify the electrodes interconnection in 3D devices.Based on this method,we fabricate 3D vertical core-double shell structure transistors with ZnO channel and Al_(2)O_(3) gate-oxide both grown by atomic layer deposition.Suspended top electrodes of vertical architecture could be directly connected to planar electrodes by FIB deposited Pt nanowires,which avoid cumbersome steps in the traditional 3D structure fabrication technology.Both single pillar and arrays devices show well behaved transfer characteristics with an Ion/Ioff current ratio greater than 106 and a low threshold voltage around 0 V.The ON-current of the 2×2 pillars vertical channel transistor was 1.2μA at the gate voltage of 3 V and drain voltage of 2 V,which can be also improved by increasing the number of pillars.Our method for fabricating vertical architecture transistors can be promising for device applications with high integration density and low power consumption. 展开更多
关键词 three-dimensional(3D)vertical ZnO transistor focused ion beam(FIB) suspended electrodes the electrical inter-connection in 3D devices
下载PDF
Integration system research and development for three-dimensional laser scanning information visualization in goaf 被引量:1
3
作者 罗周全 黄俊杰 +2 位作者 罗贞焱 汪伟 秦亚光 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2016年第7期1985-1994,共10页
An integration processing system of three-dimensional laser scanning information visualization in goaf was developed. It is provided with multiple functions, such as laser scanning information management for goaf, clo... An integration processing system of three-dimensional laser scanning information visualization in goaf was developed. It is provided with multiple functions, such as laser scanning information management for goaf, cloud data de-noising optimization, construction, display and operation of three-dimensional model, model editing, profile generation, calculation of goaf volume and roof area, Boolean calculation among models and interaction with the third party soft ware. Concerning this system with a concise interface, plentiful data input/output interfaces, it is featured with high integration, simple and convenient operations of applications. According to practice, in addition to being well-adapted, this system is favorably reliable and stable. 展开更多
关键词 GOAF laser scanning visualization integration system 1 Introduction The goaf formed through underground mining of mineral resources is one of the main disaster sources threatening mine safety production [1 2]. Effective implementation of goaf detection and accurate acquisition of its spatial characteristics including the three-dimensional morphology the spatial position as well as the actual boundary and volume are important basis to analyze predict and control disasters caused by goaf. In recent years three-dimensional laser scanning technology has been effectively applied in goaf detection [3 4]. Large quantities of point cloud data that are acquired for goaf by means of the three-dimensional laser scanning system are processed relying on relevant engineering software to generate a three-dimensional model for goaf. Then a general modeling analysis and processing instrument are introduced to perform subsequent three-dimensional analysis and calculation [5 6]. Moreover related development is also carried out in fields such as three-dimensional detection and visualization of hazardous goaf detection and analysis of unstable failures in goaf extraction boundary acquisition in stope visualized computation of damage index aided design for pillar recovery and three-dimensional detection
下载PDF
Three-dimensional Li-ion transportation in Li_(2)MnO_(3)-integrated LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) 被引量:1
4
作者 Xue Huang Jianqing Zhao +5 位作者 Wenchang Zhu Machuan Hou Tong Zhou Liangmin Bu Lijun Gao Wei Zhang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2021年第12期376-384,I0009,共10页
Ni-rich layered cathodes(LiNi_xCo_yMn_(2)O_(2))have recently drawn much attention due to their high specific capacities.However,the poor rate capability of LiNi_xCo_yMn_(2)O_(2),which is mainly originated from the two... Ni-rich layered cathodes(LiNi_xCo_yMn_(2)O_(2))have recently drawn much attention due to their high specific capacities.However,the poor rate capability of LiNi_xCo_yMn_(2)O_(2),which is mainly originated from the twodimensional diffusion of Li ions in the Li slab and Li^(+)/Ni^(2+)cation mixing that hinder the Li^(+)diffusion,has limited their practical application where high power density is needed.Here we integrated Li_(2)MnO_(3)nanodomains into the layered structure of a typical Ni-rich LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)material,which minimized the Li^(+)/Ni^(2+)cationic disordering,and more importantly,established grain boundaries within the NCM811 matrix,thus providing a three-dimensional diffusion channel for Li ions.Accordingly,an average Li-ion diffusion coefficient(D_(Li+))of the Li_(2)MnO_(3)-integrated LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811-I)during charge/discharge was calculated to be approximately 6*10^(-10)cm~2 S^(-1),two times of that in the bare NCM811(3*10^(-10)cm~2 S^(-1)).The capacity delivered by the NCM811-I(154.5 mAh g^(-1))was higher than that of NCM811(141.3 mAh g^(-1))at 2 C,and the capacity retention of NCM811-I increased by 13.6%after100 cycles at 0.1 C and 13.4%after 500 cycles at 1 C compared to NCM811.This work provides a valuable routine to improve the rate capability of Ni-rich cathode materials,which may be applied to other oxide cathodes with sluggish Li-ion transportation. 展开更多
关键词 Ni-rich layered cathode Li_(2)MnO_(3) three-dimensional diffusion of Li ions Rate performance
下载PDF
Focusing high-energy x-rays by a P MMA compound x-ray lens on Beijing synchrotron radiation facility
5
作者 乐孜纯 梁静秋 +6 位作者 董文 朱佩平 彭良强 王维彪 黄万霞 袁清习 王寯越 《Chinese Physics B》 SCIE EI CAS CSCD 2007年第4期984-988,共5页
The x-ray compound lens is a novel refractive x-ray optical device. This paper reports the authors' recent research on a polymethyl methacrylate (PMMA) compound x-ray lens. Firstly the designing and LIGA fabricatio... The x-ray compound lens is a novel refractive x-ray optical device. This paper reports the authors' recent research on a polymethyl methacrylate (PMMA) compound x-ray lens. Firstly the designing and LIGA fabrication process for the PMMA compound x-ray lens are briefly described. Then, a method for theoretical analysis, as well as the experimental system for measurement is also introduced. Finally, the focusing spots for 8keV monochromatic x-rays by the PMMA compound x-ray lens are measured and analysed. According to the experimental results, it is concluded that the PMMA compound x-ray lens promises a good focusing performance under the high-energy x-rays. 展开更多
关键词 PMMA compound x-ray lens focusing performance Beijing synchrotron radiation facility (BSRF)
下载PDF
Three-Dimensional Analytical Modeling of Axial-Flux Permanent Magnet Drivers
6
作者 Wenhui Li Dazhi Wang +3 位作者 Shuo Cao Deshan Kong Sihan Wang Zhong Hua 《Computers, Materials & Continua》 SCIE EI 2023年第4期259-276,共18页
In this paper, the axial-flux permanent magnet driver is modeledand analyzed in a simple and novel way under three-dimensional cylindricalcoordinates. The inherent three-dimensional characteristics of the deviceare co... In this paper, the axial-flux permanent magnet driver is modeledand analyzed in a simple and novel way under three-dimensional cylindricalcoordinates. The inherent three-dimensional characteristics of the deviceare comprehensively considered, and the governing equations are solved bysimplifying the boundary conditions. The axial magnetization of the sectorshapedpermanent magnets is accurately described in an algebraic form bythe parameters, which makes the physical meaning more explicit than thepurely mathematical expression in general series forms. The parameters of theBessel function are determined simply and the magnetic field distribution ofpermanent magnets and the air-gap is solved. Furthermore, the field solutionsare completely analytical, which provides convenience and satisfactoryaccuracy for modeling a series of electromagnetic performance parameters,such as the axial electromagnetic force density, axial electromagnetic force,and electromagnetic torque. The correctness and accuracy of the analyticalmodels are fully verified by three-dimensional finite element simulations and a15 kW prototype and the results of calculations, simulations, and experimentsunder three methods are highly consistent. The influence of several designparameters on magnetic field distribution and performance is studied and discussed.The results indicate that the modeling method proposed in this papercan calculate the magnetic field distribution and performance accurately andrapidly, which affords an important reference for the design and optimizationof axial-flux permanent magnet drivers. 展开更多
关键词 three-dimensional analytical modeling cylindrical coordinates magnetic field distribution parameter sensitivity analysis performance measurement
下载PDF
Performance Analysis and Evaluation of Geometric Parameters in Stereo Deflectometry 被引量:4
7
作者 Yongjia Xu Feng Gao Xiangqian Jiang 《Engineering》 SCIE EI 2018年第6期806-815,共10页
This paper presents a novel geometric parameters analysis to improve the measurement accuracy of stereo deflectometry.Stereo deflectometry can be used to obtain form information for freeform specular surfaces.A measur... This paper presents a novel geometric parameters analysis to improve the measurement accuracy of stereo deflectometry.Stereo deflectometry can be used to obtain form information for freeform specular surfaces.A measurement system based on stereo deflectometry typically consists of a fringe-displaying screen,a main camera,and a reference camera.The arrangement of the components of a stereo deflectometry system is important for achieving high-accuracy measurements.In this paper,four geometric parameters of a stereo deflectometry system are analyzed and evaluated:the distance between the main camera and the measured object surface,the angle between the main camera ray and the surface normal,the distance between the fringe-displaying screen and the object,and the angle between the main camera and the reference camera.The influence of the geometric parameters on the measurement accuracy is evaluated.Experiments are performed using simulated and experimental data.The experimental results confirm the impact of these parameters on the measurement accuracy.A measurement system based on the proposed analysis has been set up to measure a stock concave mirror.Through a comparison of the given surface parameters of the concave mirror,a global measurement accuracy of 154.2 nm was achieved. 展开更多
关键词 Optical METROLOGY ERROR analysis STEREO DEFLECTOMETRY three-dimensional SHAPE measurement performance evaluation Simulation
下载PDF
Effects of operating conditions on the performance degradation and anode microstructure evolution of anode-supported solid oxide fuel cells 被引量:4
8
作者 Xin Yang Zhihong Du +5 位作者 Qian Zhang Zewei Lyu Shixue Liu Zhijing Liu Minfang Han Hailei Zhao 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2023年第6期1181-1189,共9页
Performance degradation shortens the life of solid oxide fuel cells in practical applications.Revealing the degradation mechanism is crucial for the continuous improvement of cell durability.In this work,the effects o... Performance degradation shortens the life of solid oxide fuel cells in practical applications.Revealing the degradation mechanism is crucial for the continuous improvement of cell durability.In this work,the effects of cell operating conditions on the terminal voltage and anode microstructure of a Ni-yttria-stabilized zirconia anode-supported single cell were investigated.The microstructure of the anode active area near the electrolyte was characterized by laser optical microscopy and focused ion beam-scanning electron microscopy.Ni depletion at the anode/electrolyte interface region was observed after 100 h discharge tests.In addition,the long-term stability of the single cell was evaluated at 700℃for 3000 h.After an initial decline,the anode-supported single cell exhibits good durability with a voltage decay rate of 0.72%/kh and an electrode polarization resistance decay rate of 0.17%/kh.The main performance loss of the cell originates from the initial degradation. 展开更多
关键词 solid oxide fuel cell Ni-YSZ anode focused ion beam Ni migration electrochemical performance
下载PDF
Ablation Performance of a Novel Super-hybrid Composite 被引量:3
9
作者 JunQIU XiaomingCAO +1 位作者 ChongTIAN JinsongZHANG 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2005年第2期269-273,共5页
A novel super-hybrid composite (NSHC) was boron-modified phenolic resin (BPR) with three-dimensional reticulated SiC ceramic (3DRC) and high silica fibers. Ablation performance of the NSHC was studied. The results sho... A novel super-hybrid composite (NSHC) was boron-modified phenolic resin (BPR) with three-dimensional reticulated SiC ceramic (3DRC) and high silica fibers. Ablation performance of the NSHC was studied. The results show that the linear ablation rate of NSHC was lower than that of pure BPR and the high silica/BPR composite. Its linear ablation rate is 1/17 of the high silica/BPR. Mass ablation rate of the NSHC is very close to that of the pure BPR and the high silica/BPR composite. Scanning electron microscope (SEM) analysis indicates that 3DRC has scarcely changed its shape at the ablation temperature. Its special reticulated structure can restrict the materials deformation and prevent high velocity heat flow from eroding the surface of the materials largely and thus increase ablation resistance of the NSHC. 展开更多
关键词 Ablation performance High silica fiber Modified phenolic resin three-dimensional reticulated SiC ceramic Super-hybrid composite materials
下载PDF
Three-dimensional ultrasound subwavelength arbitrary focusing with broadband sparse metalens 被引量:1
10
作者 Xue Jiang JiaJie He +4 位作者 ChuanXin Zhang HuaLiang Zhao WeiQi Wang DeAn Ta Cheng-Wei Qiu 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2022年第2期50-56,共7页
Ultrasound focusing in three-dimensional(3 D)space is of crucial and enduring significance in a variety of biomedical and industrial applications.Conventional ultrasound focusing based on active phase array or passive... Ultrasound focusing in three-dimensional(3 D)space is of crucial and enduring significance in a variety of biomedical and industrial applications.Conventional ultrasound focusing based on active phase array or passive geometry of bulky size is unable to realize the 3 D arbitrary focusing with subwavelength resolution.Acoustic metamaterial of complex deep-subwavelength microstructure has facilitated the advanced airborne-sound-focusing but is inevitably not applicable for underwater ultrasound,restricted by the law between the multi-modes coupling/thermal viscosity and the feature size of the structure.Here,we aim to circumvent the restriction by increasing the feature size of the metamaterial while keeping the compact overall geometry,and realize the robust subwavelength ultrasound focusing with the sparse metalens of the wavelength-scale meta-atom.We theoretically propose and demonstrate numerically and experimentally the broadband arbitrary ultrasound focusing in 3 D space.The axial and off-axis ultrasound focusing with the subwavelength resolution(FWHM<0.58λ)are achieved by the spatially sparse and compact metalens within one-octave bandwidth.With advantages of 3 D freewheeling focusing,subwavelength resolution,spatial sparsity,geometric simplicity,and broadband,the sparse metalens would offer more initiatives to advanced researches in ultrasound focusing and empower applications such as precise biomedical imaging and therapy,nondestructive evaluation,integrated and multiplexed ultrasound devices. 展开更多
关键词 broadband ultrasound focusing sparse metalens subwavelength resolution three-dimensional focusing
原文传递
Heat transfer performance testing of a new type of phase change heat sink for high power light emitting diode 被引量:2
11
作者 XIANG Jian-hua ZHANG Chun-liang +2 位作者 ZHOU Chao LIU Gui-yun ZHOU Wei 《Journal of Central South University》 SCIE EI CAS CSCD 2018年第7期1708-1716,共9页
In view of the limitations of solid metal heat sink in the heat dissipation of high power light emitting diode (LED), a kind of miniaturized phase change heat sink is developed for high power LED packaging. First, t... In view of the limitations of solid metal heat sink in the heat dissipation of high power light emitting diode (LED), a kind of miniaturized phase change heat sink is developed for high power LED packaging. First, the fabrication process of miniaturized phase change heat sink is investigated, upon which all parts of the heat sink are fabricated including main-body and end-cover of the heat sink, the formation of three-dimensional boiling structures at the evaporation end, the sintering of the wick, and the encapsulation of high power LED phase change heat sink. Subsequently, with the assistance of the developed testing system, heat transfer performance of the heat sink is tested under the condition of natural convection, upon which the influence of thermal load and working medium on the heat transfer performance is investigated. Finally, the heat transfer performance of the developed miniaturized phase change heat sink is compared with that of metal solid heat sink. Results show that the developed miniaturized phase change heat sink presents much better heat transfer performance over traditional metal solid heat sink, and is suitable for the packaging of high power LED. 展开更多
关键词 miniaturized phase change heat sink three-dimensional microgrooves sintered wick heat transfer performance testing
下载PDF
Three-dimensional multiple optical cages formed by focusing double-ring shaped radially and azimuthally polarized beams 被引量:2
12
作者 Tingting Zeng Jianping Ding 《Chinese Optics Letters》 SCIE EI CAS CSCD 2018年第3期44-47,共4页
We propose and simulate a method for generating a three-dimensional (3D) optical cage in the vicinity of focus by focusing a double-ring shaped radially and azimuthally polarized beam. Our study shows that the combi... We propose and simulate a method for generating a three-dimensional (3D) optical cage in the vicinity of focus by focusing a double-ring shaped radially and azimuthally polarized beam. Our study shows that the combination of an inner ring with an azimuthally polarized field and an outer ring with a radially polarized field and a phase factor can produce an optical cage with a dark region enclosed by higher intensity. The shape of the cage can be tailored by appropriately adjusting the parameters of double-mode beams. Furthermore, multiple 3D optical cages can be realized by applying the shift theorem of the Fourier transform and macro-pixel sampling algorithm to a double-ring shaped radially and azimuthally polarized beam. 展开更多
关键词 three-dimensional multiple optical cages formed by focusing double-ring shaped radially and azimuthally polarized beams
原文传递
A theoretical method based on Fourier spectrum analysis for the focusing performances of the X-ray compound refractive lenses 被引量:1
13
作者 叶坚 乐孜纯 +4 位作者 梁静秋 刘恺 全必胜 覃亚丽 朱广信 《Chinese Optics Letters》 SCIE EI CAS CSCD 2004年第6期367-369,共3页
It is important to predict the intensity distribution in focusing plane for designing the X-ray compound refractive lenses. On the basis of analyzing the structure of X-ray compound lenses and comparing it with Praunh... It is important to predict the intensity distribution in focusing plane for designing the X-ray compound refractive lenses. On the basis of analyzing the structure of X-ray compound lenses and comparing it with Praunhofer diffraction system, it is concluded that the X-ray focusing system can be regarded as a kind of Praunhofer diffraction system. Therefore, a method based on Fourier spectrum analysis is presented to predict the intensity distribution in the focusing plane for the X-ray lenses. A brief analysis on the relationship between the parameters of X-ray lenses and their focusing performance is also given in this paper. 展开更多
关键词 A theoretical method based on Fourier spectrum analysis for the focusing performances of the X-ray compound refractive lenses
原文传递
多毛细管中子聚焦透镜仿真模拟及实验研究
14
作者 崔靖朵 刘志国 +1 位作者 温今甫 潘秋丽 《北京师范大学学报(自然科学版)》 CAS CSCD 北大核心 2024年第2期176-182,共7页
为了分析中子波长,透镜几何参数对透镜聚焦性能的影响,利用MATLAB进行仿真建模和编程,根据射线追迹法模拟中子束在透镜中的传输;利用中国散裂中子源提供的0.10~1.18 nm波段多色中子束测试透镜聚焦性能.结果表明,透镜对所测宽波段中子束... 为了分析中子波长,透镜几何参数对透镜聚焦性能的影响,利用MATLAB进行仿真建模和编程,根据射线追迹法模拟中子束在透镜中的传输;利用中国散裂中子源提供的0.10~1.18 nm波段多色中子束测试透镜聚焦性能.结果表明,透镜对所测宽波段中子束调控所得焦斑的模拟值562.0μm和实测值549.0μm非常接近,验证了仿真模型和程序的正确性.对实测焦斑数据进行分析得出:该透镜适用于0.20~1.18 nm波段;在适用波段内,焦斑尺寸与波长呈正相关,增益整体呈现先增大后降低的趋势.对通道内径变量系列仿真发现,在保证内外径比为0.8的前提下,降低微通道内径有利于获得具有高倍增益的小焦斑. 展开更多
关键词 反射与折射 中子聚焦器件 聚焦性能 中子波长 微通道内径
下载PDF
聚焦换能器声场特性的快速检验方法
15
作者 马蕊生 李文溢 +3 位作者 胡济民 李禹志 郭各朴 马青玉 《南京师范大学学报(工程技术版)》 CAS 2024年第2期20-27,49,共9页
高强度聚焦超声(HIFU)已在无创肿瘤治疗方面展示出巨大的应用潜力,而换能器聚焦性能的优劣对疗效起到至关重要的作用,因此声场的精确测量成为实际应用的重要保障.由于加工工艺和安装精度的限制,聚焦换能器的实际声场和理想声场可能存在... 高强度聚焦超声(HIFU)已在无创肿瘤治疗方面展示出巨大的应用潜力,而换能器聚焦性能的优劣对疗效起到至关重要的作用,因此声场的精确测量成为实际应用的重要保障.由于加工工艺和安装精度的限制,聚焦换能器的实际声场和理想声场可能存在一定偏差.针对传统三维扫描测量存在速度慢和精度低的问题,提出了一种基于双平面双精度测量的聚焦换能器声场特性快速检验方法.通过沿理想z轴的高精度一维扫描确定换能器倾斜角范围,在声压极值点所在横截面内利用低精度和高精度变邻域搜索法实现最大声压点的精准定位,进一步通过焦域内双平面最大声压点构建声场的实际轴线,完成实际声场焦点的精确定位,最后基于实际焦平面内轴向与径向的高精度测量结果,计算获得焦域尺寸、旁瓣大小、分布对称性和声功率等性能参数.利用构建的声场扫描实验系统对聚焦换能器声场进行三维扫描和快速测量,结果表明在相同的测量精度(0.1 mm)下可以有效提高测量速度百倍以上,具有测量速度快、测量精度易于调节和性能分析全面等优点.方法为聚焦换能器检验提供一种高精度的快速声场测量新技术,在超声治疗仪器的检验中具有重要的指导意义与应用价值. 展开更多
关键词 聚焦换能器声场 双平面双精度测量 变邻域搜索法 性能参数
下载PDF
Three-dimensional Numerical Study on Thermal Performance of a Super Large Natural Draft Cooling Tower of 220m Height 被引量:5
16
作者 JIN Tai ZHANG Li +1 位作者 LUO Kun FAN Jianren 《Journal of Thermal Science》 SCIE EI CAS CSCD 2013年第3期234-241,共8页
Based on the heat and mass transfer theory and the characteristics of general-purpose software FLUENT, a three-dimensional numerical simulation platform, composed of lots of user defined functions(UDF), has been devel... Based on the heat and mass transfer theory and the characteristics of general-purpose software FLUENT, a three-dimensional numerical simulation platform, composed of lots of user defined functions(UDF), has been developed to simulate the thermal performance of natural draft wet cooling towers(NDWCTs). After validation, this platform is used to analyse thermal performances of a 220m high super large cooling tower designed for inland nuclear plant under different operational conditions. Variations of outlet temperature of the cooling tower caused by changes of water flow rates, inlet water temperatures are investigated. Effects of optimization through non-uniform water distributions on outlet water temperature are discussed, and the influences on the flow field inside the cooling tower are analyzed in detail. It is found that the outlet water temperature will increase as the water flow rate increases, but the air flow rate will decrease. The outlet water temperature will decrease 0.095K and 0.205K, respectively, if two non-uniform water distribution approaches are applied. 展开更多
关键词 Super LARGE Natural Draft WET Cooling TOWER three-dimensional Numerical Simulation Thermal performance NON-UNIFORM Water Distribution
原文传递
环阵多阵元合成孔径成像F数优化研究
17
作者 袁旭婷 王红亮 +1 位作者 石丽帆 张文栋 《中国测试》 CAS 北大核心 2024年第9期46-55,共10页
使用环形阵列的超声计算机断层扫描(USCT)在乳腺组织成像和工业无损检测方面展示了显著潜力,但图像重建质量仍面临挑战。该研究提出将F数应用于多阵元合成孔径聚焦成像方法,在环形阵列中实现对目标的自动扫查,并探讨F数对环形阵列合成... 使用环形阵列的超声计算机断层扫描(USCT)在乳腺组织成像和工业无损检测方面展示了显著潜力,但图像重建质量仍面临挑战。该研究提出将F数应用于多阵元合成孔径聚焦成像方法,在环形阵列中实现对目标的自动扫查,并探讨F数对环形阵列合成孔径成像的影响。通过仿真和实验,使用乳腺仿真模型和直径0.3 mm的尼龙丝作为测试对象,设置发射和接收F数为F、F/2、F/4、F/8、F/16进行图像重建,并进行阈值分割处理和半高宽(FWHM)分析。结果显示,较低接收F数能够显著减少靶标畸变并提高成像精度,其重建图像尺寸误差减少了28.3%。对于点目标,低接收F数显著提高了空间分辨率,其中轴向分辨率提升了40%,横向分辨率提升了36.7%。该研究为提升环形阵列USCT成像性能提供了新的思路和方法。 展开更多
关键词 超声计算机断层扫描(USCT)成像 环形阵列 F数 多阵元合成孔径聚焦(M-SAF)成像 自动扫查 成像性能
下载PDF
基于模糊意见集中决策法的再生沥青混合料生产工艺
18
作者 郭思怡 冯振刚 +2 位作者 曲建涛 刘淼 李英勇 《公路交通科技》 CAS CSCD 北大核心 2024年第12期67-76,共10页
拌和温度、拌和时间、掺料拌和次序和储存时间在生产过程中的波动会显著影响再生沥青混合料的路用性能。为了探究这些因素对再生沥青混合料路用性能的影响,采用马歇尔试验设计了再生沥青路面材料(RAP)掺量为20%的再生沥青混合料AC-16C,... 拌和温度、拌和时间、掺料拌和次序和储存时间在生产过程中的波动会显著影响再生沥青混合料的路用性能。为了探究这些因素对再生沥青混合料路用性能的影响,采用马歇尔试验设计了再生沥青路面材料(RAP)掺量为20%的再生沥青混合料AC-16C,并在不同生产工艺参数下成型试件。通过车辙试验、低温弯曲试验、冻融劈裂试验和浸水马歇尔试验分别测定了再生沥青混合料的动稳定度、最大弯拉应变、冻融劈裂强度比和残留稳定度等主要性能指标。基于再生沥青混合料的体积参数与路用性能指标,采用模糊意见集中决策法对各项试验指标进行综合评价。通过计算不同生产工艺方案下的Borda值,确定了再生沥青混合料的最佳生产工艺参数。结果表明:对于RAP总掺量为20%的AC-16C再生沥青混合料,最佳拌和温度为165℃,此时混合料具有良好的高温稳定性、低温抗裂性和水稳定性;最佳拌和时间为180 s,能够确保新旧材料充分融合并防止过度老化;最佳拌和次序为先将RAP干拌45 s,再加入新沥青搅拌45 s,最后加入矿粉拌和90 s,这种拌和顺序可使混合料更加均匀密实;在150℃下储存0.5 h可以进一步促进新旧沥青的融合,提高混合料的综合路用性能。 展开更多
关键词 道路工程 生产工艺 模糊意见集中决策法 再生沥青混合料 路用性能
下载PDF
A method based on diffraction theory for predicting 3D focusing performance of compound refractive X-ray lenses 被引量:5
19
作者 乐孜纯 刘恺 梁静秋 《Chinese Optics Letters》 SCIE EI CAS CSCD 2005年第3期184-186,共3页
A method based on the diffraction theory for estimating the three-dimensional (3D) focusing performance of the compound refractive X-ray lenses is presented in this paper. As a special application, the 3D X-ray intens... A method based on the diffraction theory for estimating the three-dimensional (3D) focusing performance of the compound refractive X-ray lenses is presented in this paper. As a special application, the 3D X-ray intensity distribution near the focus is derived for a plano-concave compound refractive X-ray lens. Moreover, the computer codes are developed and some results of 3D focusing performance for a compound refractive X-ray lens with Si material are shown and discussed. 展开更多
关键词 A method based on diffraction theory for predicting 3D focusing performance of compound refractive X-ray lenses
原文传递
Mechanical behavior and permeability properties of sustainable and high-performance anisotropic three-dimensional printable concrete
20
作者 Fatih OZALP 《Frontiers of Structural and Civil Engineering》 SCIE EI CSCD 2023年第11期1662-1674,共13页
Three-dimensional printable concrete requires further development owing to the challenges encountered,including its brittle behavior,high cement requirement for the buildability of layers,and anisotropic behavior in d... Three-dimensional printable concrete requires further development owing to the challenges encountered,including its brittle behavior,high cement requirement for the buildability of layers,and anisotropic behavior in different directions.The aim of this study is to overcome these challenges.First,three-dimensional printable concrete mixtures were prepared using silica fume,ground blast furnace slag,and metakaolin,instead of cement,to reduce the amount of cement.Subsequently,the rheological and mechanical behaviors of these concretes were investigated.Second,threedimensional printable concrete mixtures were prepared using 6-mm-long steel and synthetic fibers to eliminate brittleness and determine the effect of those fibers on the anisotropic behavior of the concrete.As a result of this study,it is understood that printable concretes with extremely low permeability and high buildability can be achieved using mineral additives.In addition,results showed that three-dimensional concrete samples containing short steel fibers achieve fracture energies up to 36 times greater than that of plain concrete.Meanwhile,its characteristic length values,as indicators of ductility,are 22 times higher than those of plain concrete.The weakest strength was recorded at the interfaces between layers.The bending and splitting tensile strengths of three-dimensional printed plain concrete samples were 15%and 19%lower than those of casted samples,respectively.However,the addition of fibers improved the mechanical strength of the interfaces significantly. 展开更多
关键词 three-dimensional concrete printing RHEOLOGY high performance mineral additives ANISOTROPY fiber
原文传递
上一页 1 2 6 下一页 到第
使用帮助 返回顶部