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Optimum Profiles of Endwall Contouring for Enhanced Net Heat Flux Reduction and Aerodynamic Performance 被引量:1
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作者 Arjun K S Tide P S Biju N 《Journal of Harbin Institute of Technology(New Series)》 CAS 2024年第2期80-92,共13页
Successfully utilized non-axisymmetric endwalls to enhance turbine efficiencies(aerodynamic and turbine inlet temperatures)by controlling the characteristics of the secondary flow in a blade passage.This is accomplish... Successfully utilized non-axisymmetric endwalls to enhance turbine efficiencies(aerodynamic and turbine inlet temperatures)by controlling the characteristics of the secondary flow in a blade passage.This is accomplished by steady-state numerical hydrodynamics and deep knowledge of the field of flow.Because of the interaction between mainstream and purge flow contributing supplementary losses in the stage,non-axisymmetric endwalls are highly susceptible to the inception of purge flow exit compared to the flat and any advantage rapidly vanishes.The conclusions reveal that the supreme endwall pattern could yield a lowering of the gross pressure loss at the design stage and is related to the size of the top-loss location being productively lowered.This has led to diminished global thermal exchange lowered in the passage of the vane alone.The reverse flow adjacent to the suction side corner of the endwall is migrated farther from the vane surface,as the deviated pressure spread on the endwall accelerates the flow and progresses the reverse flow core still downstream.The depleted association between the tornado-like vortex and the corner vortex adjacent to the suction side corner of the endwall is the dominant mechanism of control in the contoured end wall.In this publication,we show that the non-axisymmetric endwall contouring by selective numerical shape change method at most prominent locations is advantageous in lowering the thermal load in turbines to augment the net heat flux reduction as well as the aerodynamic performance using multi-objective optimization. 展开更多
关键词 endwall contouring turbine VANE heat transfer phantom cooling coolant injection net heat flux reduction aerodynamic performance
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Microstrip Patch Antenna with an Inverted T-Type Notch in the Partial Ground for Breast Cancer Detections
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作者 Nure Alam Chowdhury Lulu Wang +2 位作者 Md Shazzadul Islam Linxia Gu Mehmet Kaya 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第2期1301-1322,共22页
This study designs a microstrip patch antenna with an inverted T-type notch in the partial ground to detect tumorcells inside the human breast.The size of the current antenna is small enough(18mm×21mm×1.6mm)... This study designs a microstrip patch antenna with an inverted T-type notch in the partial ground to detect tumorcells inside the human breast.The size of the current antenna is small enough(18mm×21mm×1.6mm)todistribute around the breast phantom.The operating frequency has been observed from6–14GHzwith a minimumreturn loss of−61.18 dB and themaximumgain of current proposed antenna is 5.8 dBiwhich is flexiblewith respectto the size of antenna.After the distribution of eight antennas around the breast phantom,the return loss curveswere observed in the presence and absence of tumor cells inside the breast phantom,and these observations showa sharp difference between the presence and absence of tumor cells.The simulated results show that this proposedantenna is suitable for early detection of cancerous cells inside the breast. 展开更多
关键词 Antenna microwave wideband cancer breast phantom tumor detection
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循环纯phantom态射
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作者 魏敏敏 赵仁育 《吉林大学学报(理学版)》 CAS 北大核心 2024年第2期249-255,共7页
通过引入循环纯phantom态射的概念,给出循环纯phantom态射的一些等价刻画,证明每个R-模都有核为循环纯内射模的满的循环纯phantom覆盖,并讨论循环纯phantom预覆盖在环变换下的传递性.
关键词 循环纯 循环纯phantom态射 预覆盖
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Effect of transcranial direct current stimulation on supernumerary phantom limb pain in spinal cord injured patient:A case report
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作者 Hyo-Sik Park Jae-Hyung Kim 《World Journal of Clinical Cases》 SCIE 2024年第17期3177-3182,共6页
BACKGROUND Supernumerary phantom limb(SPL)sensation is the experience of additional limbs,either single or a pair of limbs.Unique to traumatic spinal cord injuries,we report effect of transcranial direct current stimu... BACKGROUND Supernumerary phantom limb(SPL)sensation is the experience of additional limbs,either single or a pair of limbs.Unique to traumatic spinal cord injuries,we report effect of transcranial direct current stimulation(tDCS)on SPL pain in a patient with cervical cord injury.CASE SUMMARY The subject was a 57-year-old man who was diagnosed with complete spinal cord injury(C6/C5,motor level;C5/C5,sensory level;AIS-A)approximately three months ago.After a period of 2 wk,we administered anodal tDCS over the motor cortex for 15 minutes at an intensity of 1.5 mA.Following that treatment,the patient experienced a decrease of SPL pain intensity and frequency,which lasted for 1 week after the end of treatment.CONCLUSION Targeting the motor cortex through neuromodulation appears to be a promising option for the management of SPL pain. 展开更多
关键词 Supernumerary phantom limb pain Spinal cord injury transcranial Direct Current Stimulation NEUROMODULATION Case report
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Reconstructive surgery for phantom and residual limb pain in post-conflict settings
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作者 Damián Palafox 《Chinese Journal of Plastic and Reconstructive Surgery》 2024年第1期54-55,共2页
Traumatic amputations remain one of the most frequent and disturbing wounds of armed conflict.In this scenario,most amputees develop residual and phantom limb pain,impacting their quality of life.There are several ele... Traumatic amputations remain one of the most frequent and disturbing wounds of armed conflict.In this scenario,most amputees develop residual and phantom limb pain,impacting their quality of life.There are several elective surgical procedures available for both conditions,such as neuroma excision followed by nerve reconstruction,nerve relocation,e.g.,surgically implanting a transected nerve into a muscle,nerve transfers in cases of associated paralysis,and most recently,regenerative peripheral nerve interface surgery.Whenever possible in the post-conflict phase,a coordinated effort between traveling humanitarian surgeons specializing in reconstructive microsurgery and local healthcare providers is essential for successfully treating phantom and chronic residual limb pain in post-conflict amputees.While providing a detailed logistical framework for global humanitarian missions is beyond the scope of this article,we provide a brief perspective on a topic of utmost importance for reconstructive surgeons worldwide:the high-quality care and treatment of refugees and those whose lives have been impacted by conflict,disaster,or displacement. 展开更多
关键词 Residual limb pain Phantom limb pain Refugees Reconstructive surgery MICROSURGERY AMPUTEES
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Preclinical Verification of Modulated Electro-Hyperthermia —Part I. In Vitro Research
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作者 Andras Szasz 《International Journal of Clinical Medicine》 CAS 2024年第7期257-298,共42页
Modulated electro-hyperthermia (mEHT) targets tissue’s natural electric and thermal heterogeneities to heat the cancer cells selectively. The applied 13.56 MHz radiofrequency (RF) is a carrier of the low-frequency mo... Modulated electro-hyperthermia (mEHT) targets tissue’s natural electric and thermal heterogeneities to heat the cancer cells selectively. The applied 13.56 MHz radiofrequency (RF) is a carrier of the low-frequency modulation. The high-frequency part was chosen to select the malignant lesion using the specialties of the tumor: the higher conductivity and dielectric constant of the tumor than its host. The electric field selects the tumor, and the low-frequency amplitude modulation polarizes and excites the transmembrane proteins of the malignant cells. The dominant absorption of the energy by the microscopic clusters of the membrane rafts acts like nanoparticle heating. Exciting the membrane produces various apoptotic signals. The processes were modeled using silico and phantom experiments, which proved the concept. The preclinical verification was made in vitro and in vivo, and in the end, clinical proofs validated the method. Our objective is to follow all the development steps from the laboratory to the clinics in a trilogy of articles. This present is the first part, which deals with in silico, phantom, and in vitro research. 展开更多
关键词 Modulated Electro-Hyperthermia mEHT In Silico Calculations Phantom Measurement In Vitro Experiments Thermal Effects Nonthermal Processes Apoptosis
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Convenient model of hard tissue simulation for dental radiographic research and instruction
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作者 Etiene Andrade Munhoz Claudio Roberto Gaiao Xavier +2 位作者 Roberto Ponce Salles Ana Lúcia Alvares Capelozza Augusto Vanni Bodanezi 《World Journal of Methodology》 2024年第1期80-86,共7页
BACKGROUND The authors describe a technique for building an alternative jawbone phantom using dental gypsum and rice for research and dental radiology instruction.AIM To investigate the potential of an alternative pha... BACKGROUND The authors describe a technique for building an alternative jawbone phantom using dental gypsum and rice for research and dental radiology instruction.AIM To investigate the potential of an alternative phantom to simulate the trabecular bone aspect of the human maxilla in periapical radiographs.METHODS Half-maxillary phantoms built from gypsum-ground rice were exposed to X-rays,and the resulting images(experimental group)were compared to standardized radiographic images produced from dry human maxillary bone(control group)(n=7).The images were blindly assessed according to strict criteria by three examiners for the usual trabecular aspects of the surrounding bone,and significant differences between groups and in assessment reliability were compared using Fisher’s exact and kappa tests(α=0.05).RESULTS The differences in the trabecular aspects between groups were not statistically significant.In addition,interobserver agreement among observers was 0.43 and 0.51 for the control and experimental groups,respectively,whereas intraobserver agreement was 0.71 and 0.73,respectively.CONCLUSION The tested phantom seemed to demonstrate potential for trabecular bone image Munhoz EA et al.Model of hard tissue simulation for dental radiography WJM https://www.wjgnet.com 2 March 20,2024 Volume 14 Issue 1 simulation on maxillary periapical radiographs. 展开更多
关键词 PHANTOM RADIOLOGY Education Endodontic treatment Bone trabecular
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免像控大疆Phantom4 RTK无人机在航电枢纽工程中的应用
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作者 和卫雄 易俊杰 《四川水利》 2024年第S01期97-101,共5页
免像控技术对提高航测技术的工作效率方面具有重要的意义,采用大疆Phantom4 RTK无人机和倾斜环绕航测技术得到龙溪口航电枢纽工程的原始影像数据,运用三维实景建模软件ContextCapture建立龙溪口航电枢纽工程的三维实景模型,使用蓝景PSG... 免像控技术对提高航测技术的工作效率方面具有重要的意义,采用大疆Phantom4 RTK无人机和倾斜环绕航测技术得到龙溪口航电枢纽工程的原始影像数据,运用三维实景建模软件ContextCapture建立龙溪口航电枢纽工程的三维实景模型,使用蓝景PSG 3D裸眼三维全数字测量系统绘制龙溪口航电枢纽工程的地形图,同时使用徕卡全站仪用传统测量方法得到检核点的三维数据进行精度比对分析,结果是0.043 m的平面点中误差和0.022 m的高程点位中误差,精度均符合规范要求。 展开更多
关键词 航电枢纽 大疆Phantom4 RTK无人机 免像控
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基于分级的PHANTOM交易一致排序协议研究
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作者 胡班班 李鸿光 《西安交通工程学院学术研究》 2024年第1期24-29,共6页
DAG(Directed Acyclic Graph)分布式账本是对比特币中存在的一些交易确认时间过长等问题的改进。DAG分布式账本具有交易速度快,吞吐量大等优点。DAG分布式账本的主要优点是交易效率高,交易不用打包,做轻量级的工作量证明(POW)就可以直... DAG(Directed Acyclic Graph)分布式账本是对比特币中存在的一些交易确认时间过长等问题的改进。DAG分布式账本具有交易速度快,吞吐量大等优点。DAG分布式账本的主要优点是交易效率高,交易不用打包,做轻量级的工作量证明(POW)就可以直接发布交易,但是DAG分布式账本中异步的发布交易带来了全局交易一致性排序的困难问题。PHANTOM协议是DAG分布式账本中的一种具体的协议。PHANTOM协议中交易的排序需要求解一个NP困难问题,因此不适合于实际应用。为了避免这种复杂的计算,高效的贪心算法GHOSTDAG协议是对PHANTOM协议的改进,不仅提高了吞吐量,而且增加了抵抗双花攻击的能力。GHOSTDAG协议使用连通度得分较高的链作为主链,再利用连通度得分对区块做线性排序,当连通度得分相同时,使用哈希函数打破僵局(tie-breaking),选择哈希值较小的排在前面。但是哈希函数是伪随机函数,因此这一排序不尽合理。本文提出了基于分级的PHANTOM区块一致排序协议,采用了区块分级的概念,解决了PHANTOM协议中区块排序不唯一性的问题,并且该协议排序速度更快,且排序更合理,吞吐量更大。模拟实验评估和分析表明:基于分级的PHANTOM交易一致排序协议方案的吞吐量为1300TPS,较之前的PHANTOM协议有显著的增加,并且新方案具有安全性和可扩展性。 展开更多
关键词 DAG分布式账本 PHANTOM协议 区块排序
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Hi'CT:a pixel sensor-based device for ion tomography 被引量:3
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作者 Yi-Lun Chen Hong-Kai Wang +2 位作者 Shi-Yu Zhang Hai-Bo Yang Cheng-Xin Zhao 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2023年第7期231-241,共11页
Carbon ions,commonly referred to as particle therapy,have become increasingly popular in the last decade.Accurately predicting the range of ions in tissues is important for the precise delivery of doses in heavy-ion r... Carbon ions,commonly referred to as particle therapy,have become increasingly popular in the last decade.Accurately predicting the range of ions in tissues is important for the precise delivery of doses in heavy-ion radiotherapy.Range uncertainty is currently the largest contributor to dose uncertainty in normal tissues,leading to the use of safety margins in treatment planning.One potential method is the direct relative stopping measurement(RSP)with ions.Heavy-ion CT(Hi′CT),a compact segmented full digital tomography detector using monolithic active pixel sensors,was designed and evaluated using a 430 MeV/u high-energy carbon ion pencil beam in Geant4.The precise position of the individual carbon ion track can be recorded and reconstructed using a 30μm×30μm small pixel pitch size.Two types of customized image reconstruction algorithms were developed,and their performances were evaluated using three different modules of CAT-PHAN 600-series phantoms.The RSP measurement accuracy of the tracking algorithm for different types of materials in the CTP404 module was less than 1%.In terms of spatial resolution,the tracking algorithm could achieve a 20%modulation transfer function normalization value of CTP528 imaging results at 5 lp/cm,which is significantly better than that of the fast imaging algorithm(3 lp/cm).The density resolution obtained using the tracking algorithm of the customized CTP515 was approximately 10.5%.In conclusion,a compact digital Hi'CT system was designed,and its nominal performance was evaluated in a simulation.The RSP resolution and image quality provide potential feasibility for scanning most parts of an adult body or pediatric patient,particularly for head and neck tumor treatment. 展开更多
关键词 Heavy-ion imaging Computed tomography Silicon pixel detectors Monte Carlo Phantoms RADIOTHERAPY IMAGE-GUIDED Tracking
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THUDosePD:a three-dimensional Monte Carlo platform for phantom dose assessment 被引量:2
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作者 Xi‑Yu Luo Rui Qiu +4 位作者 Zhen Wu Shu‑Chang Yan Zi‑Yi Hu Hui Zhang Jun‑Li Li 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2023年第11期40-50,共11页
Monte Carlo simulations are frequently utilized in radiation dose assessments.However,many researchers find the prevailing computing platforms to be intricate.This highlights a pressing need for a specialized framewor... Monte Carlo simulations are frequently utilized in radiation dose assessments.However,many researchers find the prevailing computing platforms to be intricate.This highlights a pressing need for a specialized framework for phantom dose evalua-tion.To address this gap,we developed a user-friendly radiation dose assessment platform using the Monte Carlo toolkit,Geant4.The Tsinghua University Phantom Dose(THUDosePD)augments the flexibility of Monte Carlo simulations in dosi-metric research.Originating from THUDose,a code with generic,functional,and application layers,THUDosePD focuses predominantly on anatomical phantom dose assessment.Additionally,it enables medical exposure simulation,intricate geometry creation,and supports both three-dimensional radiation dose analysis and phantom format transformations.The system operates on a multi-threaded parallel CPU architecture,with some modules enhanced for GPU parallel computing.Benchmark tests on the ICRP reference male illustrated the capabilities of THUDosePD in phantom dose assessment,covering the effective dose,three-dimensional dose distribution,and three-dimensional organ dose.We also conducted a voxelization conversion on the polygon mesh phantom,demonstrating the method’s efficiency and consistency.Extended applications based on THUDosePD further underline its broad adaptability.This intuitive,three-dimensional platform stands out as a valuable tool for phantom radiation dosimetry research. 展开更多
关键词 Monte Carlo PHANTOM Dose assessment VOXELIZATION Three dimensional
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无人机在校园地形图测绘中的应用 被引量:1
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作者 施艳秋 吴忠翔 +1 位作者 冯嘉城 高航 《甘肃科技》 2023年第10期67-70,共4页
无人机倾斜摄影测量技术对减少传统测量外业工作量和节省开支有重要意义。文章采用大疆Phantom 4RTK无人机进行外业测量获取校园数据影像,利用大疆智图三维建模软件建立三维模型,eps2016地理信息工作站三维测图专版软件绘制了校园二维... 无人机倾斜摄影测量技术对减少传统测量外业工作量和节省开支有重要意义。文章采用大疆Phantom 4RTK无人机进行外业测量获取校园数据影像,利用大疆智图三维建模软件建立三维模型,eps2016地理信息工作站三维测图专版软件绘制了校园二维地形图纸(CAD),实现了吉林铁道职业技术学院既有校区建筑物及二期规划校园地形图测绘,探索实践数字化测量生产体系替代传统测量生产体系的转化路径和实现方式。 展开更多
关键词 Phantom 4RTK 航测 三维实景 二维图形
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A cadaveric breast cancer tissue phantom for phase-contrast X-ray imaging applications
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作者 Cody C.Rounds Chengyue Li +2 位作者 Wei Zhou Kenneth M.Tichauer Jovan G.Brankov 《Animal Models and Experimental Medicine》 CAS CSCD 2023年第5期427-432,共6页
Background:As mammography X-ray imaging technologies advance and provide elevated contrast in soft tissues,a need has developed for reliable imaging phantoms for use in system design and component calibration.In advan... Background:As mammography X-ray imaging technologies advance and provide elevated contrast in soft tissues,a need has developed for reliable imaging phantoms for use in system design and component calibration.In advanced imaging modalities such as refraction-based methods,it is critical that developed phantoms capture the biological details seen in clinical precancerous and cancerous cases while minimizing artifacts that may be caused due to phantom production.This work presents the fabrication of a breast tissue imaging phantom from cadaveric breast tissue suitable for use in both transmission and refraction-enhanced imaging systems.Methods:Human cancer cell tumors were grown orthotopically in nude athymic mice and implanted into the fixed tissue while maintaining the native tumor/adipose tissue interface.Results:The resulting human–murine tissue hybrid phantom was mounted on a clear acrylic housing for absorption and refraction X-ray imaging.Digital breast tomosynthesis was also performed.Conclusion:Both attenuation-based imaging and refraction-based imaging of the phantom are presented to confirm the suitability of this phantom's use in both imaging modalities. 展开更多
关键词 breast tumors digital mammography imaging phantoms orthotopic animal models phasecontrast X-ray imaging
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Monte Carlo calculation of the exposure of Chinese female astronauts to earth’s trapped radiation on board the Chinese Space Station
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作者 郭义盼 闫发智 +3 位作者 方美华 张昭 成巍 郭兵 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第7期631-638,共8页
With the development of China’s crewed space mission,the space radiation risk for astronauts is increasingly prominent.This paper describes a simulation of the radiation doses experienced by a Chinese female voxel ph... With the development of China’s crewed space mission,the space radiation risk for astronauts is increasingly prominent.This paper describes a simulation of the radiation doses experienced by a Chinese female voxel phantom on board the Chinese Space Station(CSS)performed using the Monte Carlo N-Particle(MCNP)software.The absorbed dose,equivalent dose,and effective dose experienced by the voxel phantom and its critical organs are discussed for different levels of shielding of the Tianhe core module.The risk of space-radiation exposure is then assessed by comparing these doses with the current risk limits in China(the skin dose limit for short-term low-earth-orbit missions)and the NASA figures(National Council on Radiation Protection and Measurements Report No.98)for female astronauts.The results obtained can be used to guide and optimize the radiation protection provided for manned space missions. 展开更多
关键词 space radiation Chinese female voxel phantom China’s Space Station radiation exposure risk
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Quality Assuring a Ring Vortex Flow Phantom in Real-Time
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作者 Alana S. Matthews Kelvin Simatwo +3 位作者 Andrew Narracott Simone Ambrogio Adrian Walker John W. Fenner 《Open Journal of Medical Imaging》 2023年第1期11-29,共19页
Introduction: The ring vortex phantom is a novel, cost-effective prototype which generates complex and well-characterised reference flows in the form of the ring vortex. Although its reproducibility has been demonstra... Introduction: The ring vortex phantom is a novel, cost-effective prototype which generates complex and well-characterised reference flows in the form of the ring vortex. Although its reproducibility has been demonstrated, with ring speeds routinely behaving within 10% tolerances at speeds of approximately 10 - 70 cm/s, a form of real-time QA of the device at the time of imaging is needed to confirm correct function on demand in any environment. Methods: The technology described here achieves real-time QA, comprising a linear encoder, laser-photodiode array, and Doppler probe, measuring piston motion, ring speed and intra-ring velocity respectively. This instrumentation does not interfere with imaging system QA, but allows QA to be performed on both the ring vortex and the device in real-time. Results: The encoder reports the reliability of the piston velocity profile, whilst ring speed is measured by laser behaviour. Incorporation of a calibrated Doppler probe offers a consistency check that confirms behaviour of the central axial flow. For purposes of gold-standard measurement, all elements can be related to previous Laser PIV acquisitions with the same device settings. Conclusion: Consequently, ring vortex production within tolerances is confirmed by this instrumentation, delivering accurate QA in real-time. This implementation offers a phantom QA procedure that exceeds anything seen in the literature, providing the technology to enhance quantitative assessment of flow imaging modalities. 展开更多
关键词 Flow Phantom Ring Vortex Quality Assurance IMAGING
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惊艳奢华——劳斯莱斯PHANTOM SYNTOPIA
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作者 赫炎 《世界汽车》 2023年第3期22-27,共6页
“2023年3月9日,劳斯莱斯汽车公司推出了Phantom Syntopia,这是一款以高级时装为灵感启发,与荷兰著名高级时装设计师艾里斯·范·荷本合作的复杂杰作。”“Phantom Syntopia是我们有史以来创造的最雄心勃勃、最独特、高度定制的... “2023年3月9日,劳斯莱斯汽车公司推出了Phantom Syntopia,这是一款以高级时装为灵感启发,与荷兰著名高级时装设计师艾里斯·范·荷本合作的复杂杰作。”“Phantom Syntopia是我们有史以来创造的最雄心勃勃、最独特、高度定制的Phantom,并清晰表明了劳斯莱斯真正豪华的地位。在与世界最著名的设计公司、艺术家、钟表师和珠宝商20年共同努力的基础上,Phantom Syntopia终于获得了Phantom个性化定制的终极空白画布(无限可能)的地位。通过与国际知名设计师和艾里斯·范·荷本的合作,我们再次重新划定了创新、工艺和定制可行性的界限;不仅适用于汽车,而且适用于更广泛的奢侈品行业。” 展开更多
关键词 个性化定制 劳斯莱斯 奢侈品行业 时装设计师 PHANTOM 高级时装 珠宝商 国际知名
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全息针法对幻肢痛的治疗体会
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作者 白晓娟 杨帆 刘红梅 《内蒙古中医药》 2023年第1期75-77,共3页
幻肢痛(phantom limb pain,PLP)多发于残障人士,发病率高但无特效药物或治疗手段,是社会痛点。刘红梅医师基于中医“脑为元神之府”理念,结合大量临床病例观察,认为幻肢痛性质属寒属虚,病位在脑,与经络感传密切相关,治疗上选择全息针法... 幻肢痛(phantom limb pain,PLP)多发于残障人士,发病率高但无特效药物或治疗手段,是社会痛点。刘红梅医师基于中医“脑为元神之府”理念,结合大量临床病例观察,认为幻肢痛性质属寒属虚,病位在脑,与经络感传密切相关,治疗上选择全息针法脐针,重视幻肢热感感传与幻经络“气至病所”,多获良效。现介绍刘红梅医师在应用全息针法治疗幻肢痛过程中发现的值得思考的临床现象以及临床心得体会。 展开更多
关键词 幻肢痛(phantom limb pain PLP) 针灸 气至病所
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基于高速摄像技术的振动落果惯性力研究 被引量:21
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作者 蔡菲 王春耀 +2 位作者 王学农 蒋维栋 李彦峰 《西北农林科技大学学报(自然科学版)》 CSCD 北大核心 2013年第4期208-212,共5页
【目的】研究果实在激振力作用下脱离枝干的运动规律、果实振动脱落时的加速度和脱落惯性力,为振动式果品收获机的研制提供理论依据。【方法】运用果树振动装置进行了杏果侧枝振动落果试验,采用高速摄像仪对分离过程进行了跟踪拍摄,通过... 【目的】研究果实在激振力作用下脱离枝干的运动规律、果实振动脱落时的加速度和脱落惯性力,为振动式果品收获机的研制提供理论依据。【方法】运用果树振动装置进行了杏果侧枝振动落果试验,采用高速摄像仪对分离过程进行了跟踪拍摄,通过Phantom控制软件对图像进行跟踪、捕捉、分析和计算,探寻杏果实在脱离枝干过程中瞬时速度的变化规律。【结果】杏果实脱离枝干过程中瞬时速度的变化表现为增大-减小-匀速运动-杏果实与枝干完全分离,杏果实与所在枝干的相对瞬时速度最大达到1.723m/s,杏果实的脱落加速度最大为4.270×102 m/s2,脱落惯性力最大为5.124N。【结论】脱落惯性力是杏果实脱离枝干所需的最小作用力,其是确定振动式果品收获机在收获果实的过程中作用于枝干激振力大小的理论依据,也是振动式果品收获机其他性能指标的理论参考。确定适当的激振力,可以保证振动式果品收获机在采收过程中果实的采净率高,同时对果树的损伤最小。 展开更多
关键词 振动式果品收获机 振动脱落 脱落惯性力 加速度 高速摄像仪 Phantom控制软件
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受迫振动下杏果实树枝能量传递初探 被引量:9
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作者 瞿维 王春耀 +2 位作者 王学农 蔡菲 张敏敏 《西北农林科技大学学报(自然科学版)》 CSCD 北大核心 2014年第7期223-227,共5页
【目的】研究果树在外激励载荷作用下树枝能量的传递过程,揭示振动采收果实的落果机理,为机械振动式采收技术的应用提供理论依据。【方法】由机械式激振器为果实树枝提供振源进行振动采收,通过高速摄像仪对整个采收过程进行记录,再用高... 【目的】研究果树在外激励载荷作用下树枝能量的传递过程,揭示振动采收果实的落果机理,为机械振动式采收技术的应用提供理论依据。【方法】由机械式激振器为果实树枝提供振源进行振动采收,通过高速摄像仪对整个采收过程进行记录,再用高速摄像仪的Phantom控制软件对整个试验过程进行详细的分析研究,获得树枝能量传递的一般规律。【结果】果实距离树枝分叉近的地方先脱落;各采样点以距离激振源远近依次达到能量的最大值且峰值依次降低,能量峰值大约损失了15%;树枝Ⅰ与主枝的夹角为42°时获得的峰值动能较树枝Ⅱ与主枝的夹角为80°的峰值动能大40%,且角度小果实也先脱落。【结论】能量以能量波的模式在树枝中传递,在传递过程中具有滞后性和能量的损失;果枝粗细对动能的传递有较大影响,细枝上的果实脱落所需时间较长;树枝与树干的夹角越小,各采样点在摆动方向获得的动能越大,越有利于果实脱落。 展开更多
关键词 振动采收 杏果实 机械振动 能量传递 高速摄像仪 Phantom控制软件
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基于声换能器特性的磁感应磁声成像正问题分析 被引量:6
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作者 马任 殷涛 +1 位作者 张顺起 刘志朋 《生物医学工程与临床》 CAS 2012年第3期218-222,共5页
目的在考虑声换能器特性的基础上,对磁感应磁声成像的正问题进行研究,并探讨其声源的产生、传播及接收机制。方法参考CT的三维Phantom仿真模型建立磁感应磁声成像正问题的模型,并结合电磁场理论利用有限元软件comsol仿真分析模型内部电... 目的在考虑声换能器特性的基础上,对磁感应磁声成像的正问题进行研究,并探讨其声源的产生、传播及接收机制。方法参考CT的三维Phantom仿真模型建立磁感应磁声成像正问题的模型,并结合电磁场理论利用有限元软件comsol仿真分析模型内部电导率分布与磁场和磁感应电场的关系,得到模型内部的磁感应电流分布。然后再深入研究声偶极子模型,并检测分析声换能器的特性后,给出相应的仿真声信号检测结果。结果磁感应电流密度在中心位置处为0,在电导率边界处变化较大,声换能器的检测声场分布和声偶极子传播的指向性会极大的影响声换能器接收到的磁声信号的值。结论为磁感应磁声成像实验研究及由声信号重建物体内部的电导率分布提供理论基础。 展开更多
关键词 磁感应磁声成像 正问题 声换能器特性 三维Phantom模型
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