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Tunica albuginea allograft: a new model of LaPeyronie's disease with penile curvature and subtunical ossification 被引量:3
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作者 Ludovic Ferretti Thomas M Fandel +8 位作者 Xuefeng Qiu Haiyang Zhang Hazem Orabi Alex K Wu Lia Banie Guifang Wang Guiting Lin Ching-Shwun Lin Tom FLue 《Asian Journal of Andrology》 SCIE CAS CSCD 2014年第4期592-596,共5页
The pathophysiology of LaPeyronie's disease (PD) is considered to be multifactorial, involving genetic predisposition, trauma, inflammation and altered wound healing. However, these factors have not yet been valida... The pathophysiology of LaPeyronie's disease (PD) is considered to be multifactorial, involving genetic predisposition, trauma, inflammation and altered wound healing. However, these factors have not yet been validated using animal models. In this study, we have presented a new model obtained by tunica albuginea allograft. A total of 40, 16-week-old male rats were used. Of these, 8 rats served as controls and underwent a 10 × 2-mm-wide tunical excisionwith subsequent autografting, whereas the remaining 32 underwent the same excision with grafting of the defect with another rat's tunica. Morphological and functional testing was performed at 1, 3, 7 and 12 weeks after grafting. Intracavernous pressure, the degree of penile curvature and elastic fiber length were evaluated for comparison between the allograft and control groups. The tissues were obtained for histological examination. The penile curvature was significantly greater in the allografted rats as compared with the control rats. The erectile function was maintained in all rats, except in those assessed at 12 weeks. The elastin fiber length was decreased in the allografted tunica as compared to control. SMAD2 expression was detected in the inner part of the allograff, and both collagen-Ⅱ- and osteocalcin-positive cells were also noted. Tunica albuginea (TA) allograft in rats is an excellent model of PD. The persistence of curvature beyond 12 weeks and the presence of ossification in the inner layer of the TA were similar to those observed in men with PD. Validation studies using this animal model would aid understanding of the PD pathophysiology for effective therapeutic interventions. 展开更多
关键词 ALLOGRAFT animal model OsTEOGENEsIs penile curvature penile surgery peyronie's disease
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PROJECTIVELY FLAT FINSLER METRICS WITH ALMOST ISOTROPIC S-CURVATURE 被引量:3
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作者 程新跃 沈忠民 《Acta Mathematica Scientia》 SCIE CSCD 2006年第2期307-313,共7页
This article characterizes projectively fiat Finsler metrics with almost isotropic S-curvature.
关键词 Projectively flat Finsler metric s-curvature the flag curvature Randers metric
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Curvature range measurements of the arcuate fasciculus using diffusion tensor tractography
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作者 Dong Hoon Lee Cheol Pyo Hong +3 位作者 Yong Hyun Kwon Yoon Tae Hwang Joong Hwi Kim Ji Won Park 《Neural Regeneration Research》 SCIE CAS CSCD 2013年第3期244-250,共7页
Because Broca's area and Wernicke's area in the brain are connected by the arcuate fasciculus, understanding the anatomical location and morphometry of the arcuate fasciculus can help in the treatment of patients wi... Because Broca's area and Wernicke's area in the brain are connected by the arcuate fasciculus, understanding the anatomical location and morphometry of the arcuate fasciculus can help in the treatment of patients with aphasia. We measured the horizontal and vertical curvature ranges of the arcuate fasciculus in both hemispheres in 12 healthy subjects using diffusion tensor tractography. In the right hemisphere, the direct curvature range and indirect curvature range values of the arcuate fasciculus horizontal part were 121.13 ± 5.89 and 25.99 ± 3.01 degrees, respectively, and in the left hemisphere, the values were 121.83 ± 5.33 and 27.40 ± 2.96 degrees, respectively. In the right hemisphere, the direct curvature range and indirect curvature range values of the arcuate fasciculus vertical part were 43.97 ± 7.98 and 30.15 ± 3.82 degrees, respectively, and in the left hemisphere, the values were 39.39 ± 4.42 and 24.08 ± 4.34 degrees, respectively. We believe that the measured curvature ranges are important data for localization and quantitative assessment of specific neuronal pathways in patients presenting with arcuate fasciculus abnormalities. 展开更多
关键词 neural regeneration neuroimaging clinical practice diffusion tensor tractography diffusion tensor imaging arcuate fasciculus direct curvature range indirect curvature range anatomical location quantitative information APHAsIA Broca’s area Wernicke’s area arched fiber grant-supported paper photographs-containing paper NEUROREGENERATION
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Electromagnetic Gauges and Maxwell Lagrangians Applied to the Determination of Curvature in the Space-Time and their Applications
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作者 Francisco Bulnes 《Journal of Electromagnetic Analysis and Applications》 2012年第6期252-266,共15页
If we consider the finite actions of electromagnetic fields in Hamiltonian regime and use vector bundles of geodesic in movement of the charges with a shape operator (connection) that measures the curvature of a geome... If we consider the finite actions of electromagnetic fields in Hamiltonian regime and use vector bundles of geodesic in movement of the charges with a shape operator (connection) that measures the curvature of a geometrical space on these geodesic (using the light caused from these points (charges) acting with the infinite null of gravitational field (background)) we can establish a model of the curvature through gauges inside the electromagnetic context. In partular this point of view is useful when it is about to go on in a quantized version from the curvature where the space is distorted by the interactions between particles. This demonstrates that curvature and torsion effect in the space-time are caused in the quantum dimension as back-reaction effects in photon propagation. Also this permits the observational verification and encodes of the gravity through of light fields deformations. The much theoretical information obtained using the observable effects like distortions is used to establish inside this Lagrangian context a classification of useful spaces of electro-dynamic configuration for the description of different interactions of field in the Universe related with gravity. We propose and design one detector of curvature using a cosmic censor of the space-time developed through distortional 3-dimensional sphere. Some technological applications of the used methods are exhibited. 展开更多
关键词 BACK-REACTION Effects Electromagnetic BUNDLEs Form Operator Electro-Gravitational Detectors Maxwell’s Lagrangian Quantum curvature
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Surgical Treatment of Penile Deformity Due to Curvature Using a Subcutaneous Soft Silicone Implant: Case Report
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作者 James J. Elist Vaheh Shirvanian Gottfried Lemperle 《Open Journal of Urology》 2014年第7期91-97,共7页
Introduction: Congenital and acquired penile curvature has a negative impact on penile aesthetics, sexual capabilities, and male psychology. Surgical procedures yield satisfactory correction of curvature, but are usua... Introduction: Congenital and acquired penile curvature has a negative impact on penile aesthetics, sexual capabilities, and male psychology. Surgical procedures yield satisfactory correction of curvature, but are usually associated with penile shortening and palpable suture material and nodules under the skin, resulting in patient dissatisfaction. Aims: To present a novel technique using a subcutaneous soft silicone implant for surgical treatment of penile soft tissue deformities with curvature, with prevention of surgery-associated penile shortening and subcutaneous “bumps”, and with additional gains in overall penile length and girth. Method: 3 patients who complained about congenital, post-traumatic, and post-penile surgery associated penile curvature, with concerns about their penile aesthetics and associated negative psychosocial effects, were treated with the insertion of a subcutaneous soft silicone penile implant. Results: During a follow up period of 2 - 12 months (mean: 6.7 ± 3.6 months) all three patients expressed objective and subjective satisfaction regarding the corrective results of the surgery. Penile length and girth measurements during follow-up showed a mean increase in length of 4.3 cm (±1.4 cm) and a mean increase in girth of 3.0 cm (±1.0 cm). Conclusion: The insertion of the subcutaneous soft silicone implant in addition to corporeal fibrotic tissue removal in patients with congenital or acquired penile curvature is an effective option that provides the patient with aesthetic improvements by correcting penile deviation, preventing post-surgical subcutaneous nodule formation that results from the technique and suture material used, and adding penile length and girth. Further prospective studies are required to validate our initial experience. 展开更多
关键词 PENILE curvature Peyronie’s Disease PENILE Prosthesis PENILE shortening PENILE Length PENILE Girth PENILE Augmentation sUBCUTANEOUs sOFT sILICONE IMPLANT Elist sILICONE IMPLANT
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Flat Space Cosmology as a Model of Penrose’s Weyl Curvature Hypothesis and Gravitational Entropy
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作者 Eugene Terry Tatum 《Journal of Modern Physics》 2018年第10期1935-1940,共6页
FSC is shown to be an excellent model of Penrose’s Weyl curvature hypothesis and his concept of gravitational entropy. The assumptions of FSC allow for the minimum entropy at the inception of the cosmic expansion and... FSC is shown to be an excellent model of Penrose’s Weyl curvature hypothesis and his concept of gravitational entropy. The assumptions of FSC allow for the minimum entropy at the inception of the cosmic expansion and rigorously define a cosmological arrow of time. This is in sharp contrast to inflationary models, which appear to violate the second law of thermodynamics within the early universe. Furthermore, by virtue of the same physical assumptions applying at any cosmic time t, the perpetually-flat FSC model predicts the degree of scale invariance observed in the CMB anisotropy pattern, without requiring an explosive and exceedingly brief inflationary epoch. Penrose’s concepts, as described in this paper, provide support for the idea that FSC models gravitational entropy and Verlinde’s emergent gravity theory. 展开更多
关键词 FLAT space COsMOLOGY COsMOLOGY Theory GRAVITATIONAL ENTROPY Weyl’s curvature HYPOTHEsIs Black Holes COsMIC Inflation COsMIC Flatness COsMIC Microwave Background
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Measuring Method of Radius of Curvature Based on Dual-Frequency Laser Interferometer
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作者 Wenlong Zhang Liang Miao Yu Liu 《Optics and Photonics Journal》 2016年第8期209-214,共6页
In order to achieve high-accuracy measurement of radius of curvature of optical sphere, ultra-high accuracy radius of curvature testing device is developed by dual-frequency laser interferometer and Fizeau interferome... In order to achieve high-accuracy measurement of radius of curvature of optical sphere, ultra-high accuracy radius of curvature testing device is developed by dual-frequency laser interferometer and Fizeau interferometer based on cat’s eye and confocal method. Through analyzing the error source models of radius of curvature testing, optical configuration of the testing device has been optimized. Precise environment control and real-time monitoring system is also established to reduce the errors caused by environment. Through the above processes, the radius of curvature measurement relative accuracy is better than 2 ppm. One optical sphere, R88.5 mm, test aperture 59 mm, has been tested. Testing result is 88499.465 ± 0.176 μm, meeting the design requirement. The method has high accuracy and practical advantages. 展开更多
关键词 Radius of curvature Cat’s Eye and Confocal Method Dual-Frequency Laser Interferometer
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Diagnostic and surgical challenges of progressive neck and upper back painless masses in Madelung’s disease: A case report and review of literature 被引量:3
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作者 Ya-Jie Yan Shi-Qing Zhou +1 位作者 Chun-Qiao Li Yan Ruan 《World Journal of Clinical Cases》 SCIE 2022年第1期361-370,共10页
BACKGROUND Madelung’s disease(MD)is a chronic alcoholism-associated metabolic syndrome characterized by symmetrical subcutaneous deposition of adipose tissue in the head,neck,shoulders,back,trunk,and nerve roots of t... BACKGROUND Madelung’s disease(MD)is a chronic alcoholism-associated metabolic syndrome characterized by symmetrical subcutaneous deposition of adipose tissue in the head,neck,shoulders,back,trunk,and nerve roots of the upper and lower limbs.It is relatively rare in Asian individuals and is prone to misdiagnosis.Herein,we report a case of a patient with MD who had undergone surgical management at our hospital,and we discuss the pathogenesis,diagnosis,and treatment of MD.CASE SUMMARY We report a case of MD in a 65-year-old man of Han descent.The patient had multiple,painless progressive masses for more than five years in the neck and more than 30 years in the upper back.Because of neck mobility limitations and progressive cosmetic deformities caused by the masses,he was admitted to our hospital.He drank approximately 500 mL of liquor per day and smoked heavily for more than 30 years.Contrast-enhanced computed tomography of the neck and chest documented abundant unencapsulated,subcutaneous fatty deposits.We prepared a staged operation plan.The patient was diagnosed with MD;he was advised to abstain from alcohol and was followed up regularly.After a 3-month follow-up,no recurrence of fat accumulation was found in the surgical areas.CONCLUSION This report presents a case of surgical treatment for MD to improve clinicians'understanding of the disease. 展开更多
关键词 Madelung’s disease Benign symmetric lipomatosis Launois–Bensaude syndrome Multiple symmetric lipomatosis LIPECTOMY Head and neck mass Case report
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Kimura’s Disease—A Rare Cause of Head and Neck Swelling 被引量:2
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作者 Kiran Rao Sudesh Kumar 《International Journal of Otolaryngology and Head & Neck Surgery》 2014年第4期200-204,共5页
Kimura’s disease (KD) is a chronic inflammatory disorder with unknown etiology, most commonly manifesting as painless unilateral cervical lymphadenopathy or subcutaneous masses in the head or neck region. The disease... Kimura’s disease (KD) is a chronic inflammatory disorder with unknown etiology, most commonly manifesting as painless unilateral cervical lymphadenopathy or subcutaneous masses in the head or neck region. The disease is characterized by a triad of painless subcutaneous masses in the head or neck region, blood and tissue eosinophilia, and markedly elevated serum immunoglobulin E levels. Kimura’s disease is an unusual vascular tumor that typically occurs at 20 to 30 years of age. There has been no documented case of malignant transformation;however, recurrence rates after excision may be as high as 25%. Surgery and medical therapy are useful for treatment. We present a 14 years old male developed a unilateral cervical mass associated with KD. It was a recurrence of disease. As a complete excisional resection of the mass already done 1 year back at some other centre, we decided to give medical treatment for Kimura’s disease. 展开更多
关键词 Kimura’s DIsEAsE EOsINOPHILIA neck sWELLING
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顾及地球曲率及椭球高的GNSS-R几何计算方法
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作者 宋敏峰 何秀凤 +3 位作者 王笑蕾 肖儒雅 贾东振 李伟强 《测绘学报》 EI CSCD 北大核心 2023年第6期884-894,共11页
全球卫星导航系统反射测量(GNSS-R)技术中,观测几何计算不仅涉及GNSS反射信号的在轨实时处理,而且与观测值的地理位置计算直接相关,对其进行精确计算十分重要。当前GNSS-R技术逐步向陆地场景拓展,已有几何计算方法难以满足多场景(海洋... 全球卫星导航系统反射测量(GNSS-R)技术中,观测几何计算不仅涉及GNSS反射信号的在轨实时处理,而且与观测值的地理位置计算直接相关,对其进行精确计算十分重要。当前GNSS-R技术逐步向陆地场景拓展,已有几何计算方法难以满足多场景(海洋、陆地、冰川等)应用的需求。针对此,本文提出了一种顾及地球曲率和椭球高的几何计算方法。该方法同时也集成了一种镜面点初始估计模型,在不同轨道高度(300~900 km)和观测几何条件下,初始估计误差精度可降低至5 km以内。本文方法可基于WGS-84椭球面和顾及反射面椭球高精确计算镜面反射点,精度可控在1 mm以内,计算效率相比已有方法有显著提升,可对未来考虑地形高度的高效计算需求提供借鉴。本文方法通过变换迭代方程可进行反射信号的几何路径计算,实现从反射信号延迟观测到镜面反射点和椭球高的一体解算。与已有方法相比,本文方法考虑了地球曲率及反射点随椭球高度变化的空间偏移误差,可避免测高应用中测量值定位不准确的问题。 展开更多
关键词 GNss-R 几何计算 初始镜面反射点 地球曲率 椭球高
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基于YOLOv5s和改进质心跟踪的人员跌倒检测 被引量:1
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作者 王新 杨秀梅 《电子测量技术》 北大核心 2023年第24期172-178,共7页
针对目标检测器检测跌倒时过于依赖卷积网络分类效果、无法利用运动信息的问题,本文设计了一种基于YOLOv5s和改进质心跟踪的跌倒检测模型。为解决耗费资源问题,用MobileNetV3网络和Slim Neck模块对YOLOv5s进行轻量化,同时将MobileNetV3... 针对目标检测器检测跌倒时过于依赖卷积网络分类效果、无法利用运动信息的问题,本文设计了一种基于YOLOv5s和改进质心跟踪的跌倒检测模型。为解决耗费资源问题,用MobileNetV3网络和Slim Neck模块对YOLOv5s进行轻量化,同时将MobileNetV3网络中的SE模块替换为更高效的ECA模块,降低网络复杂度的同时保持较高的精度。引入哈希感知算法改进质心跟踪,增加目标关联的依据,提高跌倒检测的准确性。实验结果显示改进YOLOv5s模型大小下降52.2%,计算量下降51.8%,精度高达90.3%。改进质心跟踪的跌倒检测模型准确率提高了4.3%。结果表明了本文提出模型的有效性和优越性。 展开更多
关键词 跌倒检测 YOLOv5s 质心跟踪 slim neck 哈希感知算法
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中国新疆地区21例头颈部IgG4相关性疾病的临床分析
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作者 张蓉 高瞻 《中国美容医学》 CAS 2024年第6期112-116,共5页
目的:分析头颈部IgG4相关性疾病的临床表现、诊断、治疗和预后。方法:选取2012年1月-2023年3月笔者医院收治的21例头颈部IgG4相关性疾病患者的临床资料,并复习相关文献。结果:头颈部IgG4相关性疾病是一种多器官系统疾病,以受累器官肿胀... 目的:分析头颈部IgG4相关性疾病的临床表现、诊断、治疗和预后。方法:选取2012年1月-2023年3月笔者医院收治的21例头颈部IgG4相关性疾病患者的临床资料,并复习相关文献。结果:头颈部IgG4相关性疾病是一种多器官系统疾病,以受累器官肿胀硬化、组织纤维化、血清IgG4升高、IgG4阳性淋巴细胞和浆细胞浸润为临床特征,CT和MRI也呈现特征性表现。激素为该疾病的一线治疗药物,视病情联合使用免疫抑制剂可控制疾病复发。结论:IgG4相关性疾病临床表现多样,临床医生应警惕该疾病,避免不必要的手术。 展开更多
关键词 头颈部 新疆地区 IGG4相关性疾病 IgG4相关性涎腺炎 MIKULICZ病
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于氏丛刺联合颈椎扳法治疗神经根型颈椎病疗效观察
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作者 许嘉犇 刘士硕 +1 位作者 陈柏臻 戴缙 《辽宁中医杂志》 CAS 北大核心 2024年第10期146-149,共4页
目的探讨于氏头穴丛刺联合颈椎定位旋转扳法治疗神经根型颈椎病(CSR)的疗效及对颈肌MRI影像学指标、颈椎生理曲度变化的影响。方法选取2022年1月—2023年1月医院收治的110例CSR患者为研究对象,随机分为对照组、观察组,各55例,对照组给... 目的探讨于氏头穴丛刺联合颈椎定位旋转扳法治疗神经根型颈椎病(CSR)的疗效及对颈肌MRI影像学指标、颈椎生理曲度变化的影响。方法选取2022年1月—2023年1月医院收治的110例CSR患者为研究对象,随机分为对照组、观察组,各55例,对照组给予口服西药+曲度牵引治疗,观察组在对照组的基础上给予颈椎定位旋转扳法联合于氏头穴丛刺治疗。4周后比较颈肌MRI指标、颈椎生理曲度变化、颈椎功能与疼痛情况,评估治疗效果。结果治疗4周后,观察组左侧、右侧胸锁乳突肌长径与短径均较短(P<0.05),左侧、右侧斜方肌长径与短径均较长(P<0.05)。治疗4周后,观察组患者C_(2)~C_(7)Cobb角均大于对照组(P<0.05)。治疗4周后,观察组颈椎功能障碍指数(NDI)、视觉模拟评分法(VAS)评分均低于对照组(P<0.05)。治疗4周后,观察组临床有效率高于对照组(96.36%vs 85.45%,P<0.05)。结论在口服西药+曲度牵引治疗的基础上结合于氏头穴丛刺+颈椎定位旋转扳法,有利于改善CSR患者颈肌MRI影像学指标,促进颈椎生理曲度恢复,改善颈椎功能障碍与疼痛情况,提升治疗效果。 展开更多
关键词 于氏头穴丛刺 颈椎定位旋转扳法 神经根型颈椎病 颈椎生理曲度 颈椎功能 疼痛
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“S”形试件的五轴数控机床综合动态精度检测特性研究 被引量:15
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作者 杜丽 张信 +2 位作者 王伟 付振华 石荣波 《电子科技大学学报》 EI CAS CSCD 北大核心 2014年第4期629-635,共7页
以ISO国际标准试件、NAS979系列试件、NCG试件等为例,比较了目前国内外常用机床精度检测试件的检测性能与特点,计算了"S"形检测试件的开闭角、扭曲角、曲线曲率以及曲面法曲率等特征,研究了"S"形检测试件在几何造... 以ISO国际标准试件、NAS979系列试件、NCG试件等为例,比较了目前国内外常用机床精度检测试件的检测性能与特点,计算了"S"形检测试件的开闭角、扭曲角、曲线曲率以及曲面法曲率等特征,研究了"S"形检测试件在几何造型方面的特性,证明了"S"形试件能基本体现和覆盖机床的各种复杂姿态,以及在机床多轴联动精度检测和机床动态刚度特性检测等方面更具全面性。为基于"S"形检测试件的五轴数控机床动态精度检测提供相应的科学依据,为五轴数控机床精度检测试件的型面构造研究提供理论参考,有助于"S"形试件国际标准草案的制定与推广。 展开更多
关键词 法曲率 开闭角 反向间隙 s”形检测试件 扭曲角
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基于S-L模型的憎水性图像水珠形状提取 被引量:5
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作者 唐良瑞 于文文 陆俊 《高压电器》 CAS CSCD 北大核心 2009年第6期37-39,共3页
憎水性图像水珠形状提取是绝缘子憎水性等级评价的重要前提。Snake模型在提取边界轮廓时存在着对初始轮廓敏感、边界信息捕捉能力较差等问题,为此笔者在S-L模型的基础上,利用水珠图像的先验信息来改进S-L模型对水珠形状的提取过程,在一... 憎水性图像水珠形状提取是绝缘子憎水性等级评价的重要前提。Snake模型在提取边界轮廓时存在着对初始轮廓敏感、边界信息捕捉能力较差等问题,为此笔者在S-L模型的基础上,利用水珠图像的先验信息来改进S-L模型对水珠形状的提取过程,在一定程度上克服了Snake模型的缺点,提高了轮廓形变过程中的拓扑能力,提高了形状提取的精确度。实验结果表明,该方法有效地实现了水珠形状的提取,为后续绝缘子性能的等级评价提供依据。 展开更多
关键词 sNAKE模型 水平集模型 s-L模型 曲率
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表现为颈部肿块的Castleman病 被引量:2
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作者 朱瑾 方瑜 +3 位作者 李勇 徐如君 曹晓林 虞海婷 《医学研究杂志》 2008年第8期90-92,F0003,共4页
目的探讨表现为颈部肿块的Castleman病(Castleman disease,CD)的临床特点和诊治方法。方法报道1例并总结分析39例颈部CD患者的临床资料。结果颈部CD临床极为少见,10岁以下儿童更为罕见。临床主要表现为颈中上部无痛肿块,易与头颈部常见... 目的探讨表现为颈部肿块的Castleman病(Castleman disease,CD)的临床特点和诊治方法。方法报道1例并总结分析39例颈部CD患者的临床资料。结果颈部CD临床极为少见,10岁以下儿童更为罕见。临床主要表现为颈中上部无痛肿块,易与头颈部常见疾病混淆造成误诊甚至误治。该病的CT和MRI影像表现有一定特点。该病穿刺活检一般难以确诊,术中冷冻切片有较高诊断价值,最终确诊依靠术后常规病检。其病理类型多为透明血管型,彻底的手术切除效果良好。结论对于初步排除颈部常见疾病又疑为颈部CD的患者,应该先取活检,如被冷冻切片结果证实,再行彻底手术切除。彻底手术切除是治疗颈部CD最为有效的方法,术后随访极少复发。 展开更多
关键词 CAsTLEMAN病 颈部 临床分析 治疗方法
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基于曲率特性的柔性加减速NURBS插补器 被引量:7
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作者 富宏亚 李茂月 +1 位作者 刘源 韩振宇 《计算机集成制造系统》 EI CSCD 北大核心 2012年第9期1921-1929,共9页
为降低非均匀有理B样条段间转接时对机床的机械冲击,提出了一种基于曲率特性的柔性加减速控制方法。研究了满足插补误差要求的非均匀有理B样条梯形加减速的算法,推导了满足S型加减速要求的简化算法。用两种算法进行的基于弓高误差的非... 为降低非均匀有理B样条段间转接时对机床的机械冲击,提出了一种基于曲率特性的柔性加减速控制方法。研究了满足插补误差要求的非均匀有理B样条梯形加减速的算法,推导了满足S型加减速要求的简化算法。用两种算法进行的基于弓高误差的非均匀有理B样条仿真加工实验表明,在曲率突变处加速度和加加速度均出现突变,对机床造成较大冲击。而基于曲率变化进行的柔性加减速的仿真试验表明,相关特性参数符合加减速的规划要求。将算法集成至自行开发的开放式控制器中,加工实验表明,该算法使数控机床的速度变化更加平稳,并具有良好的实时性。 展开更多
关键词 非均匀有理B样条 s加减速 曲率 开放式控制器 机床
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两点弯曲下柔性玻璃变形和疲劳行为研究
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作者 魏韶山 饶美娟 +3 位作者 刘小根 曹大可 万德田 郑德志 《硅酸盐通报》 CAS 北大核心 2024年第9期3455-3461,3471,共8页
基于两点弯曲法加载方式及原理,分析了柔性玻璃的弯曲变形及疲劳行为,推导了弯曲曲率半径、弯曲应力与板间距之间的定量关系,基于高周疲劳理论,建立了柔性玻璃的应力-寿命(S-N_f)模型。结果表明,两点弯曲作用下,柔性玻璃试样的厚度不会... 基于两点弯曲法加载方式及原理,分析了柔性玻璃的弯曲变形及疲劳行为,推导了弯曲曲率半径、弯曲应力与板间距之间的定量关系,基于高周疲劳理论,建立了柔性玻璃的应力-寿命(S-N_f)模型。结果表明,两点弯曲作用下,柔性玻璃试样的厚度不会改变其弯曲挠曲线轨迹,通过调节板间距,可获得试验所需的试样弯曲曲率半径。忽略柔性玻璃厚度的影响,试样的弯曲曲率半径与板间距呈线性关系,弯曲最大拉应力与弯曲曲率半径成反比。选择的最小弯曲曲率半径R_(min)越大,试样疲劳寿命越高,最大弯曲曲率半径R_(max)值的增大并不会显著影响试样的弯曲疲劳次数。Basquin模型能够有效预测不同交变应力或不同弯曲曲率半径作用下柔性玻璃的弯曲疲劳寿命。 展开更多
关键词 柔性玻璃 两点弯曲 弯曲曲率半径 弯曲应力 弯曲疲劳 应力-寿命(s-N_(f))模型
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局部射影平坦且具有迷向S-曲率的两类重要的(α,β)-度量 被引量:2
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作者 蒋经农 程新跃 《西南大学学报(自然科学版)》 CAS CSCD 北大核心 2011年第12期130-132,共3页
研究了两类重要的分别形如F=α~2/(α-β)和F=α+εβ+kβ~2/α的(α,β)-度量,其中α=aij(x)yi yj为黎曼度量,β=bi(x)yi为流形上的1-形式,ε,k≠0为常数.得到了它们为局部射影平坦且具有迷向S-曲率的充要条件.
关键词 芬斯勒度量 射影平坦的芬斯勒度量 s-曲率 Β)-度量
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极小曲面的Weierstrass表示与建筑造型 被引量:3
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作者 张群力 周平槐 +1 位作者 杨学林 沈意 《土木建筑工程信息技术》 2014年第3期25-38,共14页
极小曲面广泛存在于自然界中,是平均曲率处处为0的一类重要曲面。其上含有多种相容的数学结构,可用不同的数学观点、方法来处理。局部上极小曲面定义为面积泛函的临界点,用变分方程或等价的欧拉—拉格朗日方程(二阶椭圆偏微分方程)表达... 极小曲面广泛存在于自然界中,是平均曲率处处为0的一类重要曲面。其上含有多种相容的数学结构,可用不同的数学观点、方法来处理。局部上极小曲面定义为面积泛函的临界点,用变分方程或等价的欧拉—拉格朗日方程(二阶椭圆偏微分方程)表达。可用微分方程求其解析介或近似介,也可用变分方程求其近似介。极小映射是两个黎曼流形间的特殊映射,Weierstrass抛弃面积概念,从另外一个角度给出了极小曲面方程的通解。采用极小曲面Weierstrass表示,借助于计算机绘图技术可以获得各种精美的极小曲面图形。极小曲面在拓扑上可以有随心所欲的复杂,在几何上可以有令人难以琢磨的对称。这些图形在银屏上未显示前,大多无法事先想象出来。作为应用本文绘制了实射影平面在三维欧氏空间的最佳浸入Boy’s曲面的图形。还讨论了几种用极小曲面或调和曲面造型的建筑。 展开更多
关键词 极小曲面 平均曲率 面积泛函 黎曼流形 WEIERsTRAss表示 Boy’s曲面
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