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h-Said-Ball基与h-Said-Ball曲线
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作者 刘婉柔 解滨 韩力文 《高校应用数学学报(A辑)》 北大核心 2024年第3期273-290,共18页
h-Bezier曲线是Bezier曲线基于h-微积分意义下的推广模型.为增强Said-Ball曲线的造型能力,提高h-Bezier曲线递归求值速度,该文提出任意次的h-Said-Ball基函数,构造了h-Said-Ball曲线.通过分析Said-Ball曲线递归求值算法与Bezier曲线的... h-Bezier曲线是Bezier曲线基于h-微积分意义下的推广模型.为增强Said-Ball曲线的造型能力,提高h-Bezier曲线递归求值速度,该文提出任意次的h-Said-Ball基函数,构造了h-Said-Ball曲线.通过分析Said-Ball曲线递归求值算法与Bezier曲线的转化关系,结合h-Bezier曲线的递归求值算法和h-Bernstein基函数的构造方式,得到任意次h-Said-Ball基函数的表达式.h-Said-Ball基具有非负,单位分解,端点插值等优良性质,和h-Bernstein基之间存在显式转换矩阵.进一步,定义h-Said-Ball曲线并分析其基本性质,推导递归求值算法和包络表示,h-Said-Ball曲线的求值计算量是h-Bezier曲线的一半.借助从h-Said-Ball曲线到h-Bezier曲线的割角算法,证明了h-Said-Ball基是全正基,从而h-Said-Ball曲线具有变差缩减性和保凸性.数值实例显示了h-Said-Ball曲线相比Said-Ball曲线的造型优势和灵活性. 展开更多
关键词 h-Bezier曲线 said-ball曲线 h-said-ball基函数 h-said-ball曲线 全正基 递归求值算法
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基于PatchTracker的对抗补丁防御算法 被引量:1
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作者 肖镇杰 黄诗瑀 +2 位作者 叶锋 黄丽清 黄添强 《网络与信息安全学报》 2024年第1期169-180,共12页
基于深度神经网络的目标检测技术已经广泛应用于各领域,然而,通过对抗补丁攻击在图像中添加局部扰动,以此来误导深度神经网络,对基于目标检测技术的视觉系统构成了严重威胁。针对这一问题,利用对抗补丁和图像背景的语义差异性,提出了一... 基于深度神经网络的目标检测技术已经广泛应用于各领域,然而,通过对抗补丁攻击在图像中添加局部扰动,以此来误导深度神经网络,对基于目标检测技术的视觉系统构成了严重威胁。针对这一问题,利用对抗补丁和图像背景的语义差异性,提出了一种基于PatchTracker的对抗补丁防御算法,该算法由上游补丁检测器与下游数据增强模块组成。上游补丁检测器使用带有注意力机制的YOLOV5(you only look once-v5)确定对抗补丁所在位置,有助于提高对小尺度对抗补丁的检测精度;将检测区域用合适的像素值覆盖以抹除对抗补丁,上游补丁检测器不仅能够有效降低对抗样本的攻击性,而且不依赖大规模的训练数据;下游数据增强模块通过改进模型训练范式,提高下游目标检测器的鲁棒性;将抹除补丁后的图像输入经过数据增强的下游YOLOV5目标检测模型。在公开的TT100K交通标志数据集上进行了交叉验证,实验表明,与未采取防御措施相比,所提算法能够有效防御多种类型的通用对抗补丁攻击,在检测对抗补丁图像时的mAP(mean average precision)提高65%左右,有效地改善了小尺度对抗补丁的漏检情况。与现有算法比较,所提算法有效提高了神经网络在检测对抗样本时的准确率。此外,所提算法不涉及下游模型结构的修改,具有良好的兼容性。 展开更多
关键词 深度学习安全 对抗攻击与防御 对抗补丁 目标检测
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Patch-Locator:一种基于排序学习的开源软件漏洞补丁定位方法
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作者 杨云帆 薄莉莉 +2 位作者 魏颖 吴潇雪 孙小兵 《小型微型计算机系统》 CSCD 北大核心 2024年第10期2551-2560,共10页
日益增多的开源软件漏洞对软件安全带来了巨大的风险,补丁在应对这一风险的过程中扮演了非常重要的角色.不幸的是,尽管大部分漏洞的补丁在被披露前就已经开发完毕,但仅有部分补丁会随漏洞同步公开.现有的研究发现了漏洞与其补丁之间存... 日益增多的开源软件漏洞对软件安全带来了巨大的风险,补丁在应对这一风险的过程中扮演了非常重要的角色.不幸的是,尽管大部分漏洞的补丁在被披露前就已经开发完毕,但仅有部分补丁会随漏洞同步公开.现有的研究发现了漏洞与其补丁之间存在一定的相关性,并基于这些相关性特征对提交进行了排序,以定位漏洞的补丁,但仍旧存在漏洞数据部分缺失、定位准确率不佳等问题.本文提出了Patch-Locator,一种新的基于排序学习的补丁定位方法,通过扩展漏洞数据源对漏洞数据进行补充,并根据漏洞与补丁文本的相似性、漏洞产生的原因和导致的结果等更能反映漏洞与补丁间关联的因素提取了更具有针对性的相关性特征,并使用LambdaMart排序学习模型对提交基于其具有的相关性特征进行排序以定位安全补丁.本文用来自10个开源软件项目的1669个漏洞来评估Patch-Locator.实验结果表明,Patch-Locator的Recall@1指标为92.22%,Recall@5指标为95.51%,Manual Effort@5指标为1.2455,均优于现有方法. 展开更多
关键词 开源软件 安全补丁 排序学习 补丁定位
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Formation and ecological response of sand patches in the protection system of Shapotou section of the Baotou-Lanzhou railway,China
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作者 DUN Yaoquan QU Jianjun +4 位作者 KANG Wenyan LI Minlan LIU Bin WANG Tao SHAO Mei 《Journal of Arid Land》 SCIE CSCD 2024年第2期298-313,共16页
The development of bare patches typically signifies a process of ecosystem degradation.Within the protection system of Shapotou section of the Baotou-Lanzhou railway,the extensive emergence of bare sand patches poses ... The development of bare patches typically signifies a process of ecosystem degradation.Within the protection system of Shapotou section of the Baotou-Lanzhou railway,the extensive emergence of bare sand patches poses a threat to both stability and sustainability.However,there is limited knowledge regarding the morphology,dynamic changes,and ecological responses associated with these sand patches.Therefore,we analyzed the formation and development process of sand patches within the protection system and its effects on herbaceous vegetation growth and soil nutrients through field observation,survey,and indoor analysis methods.The results showed that sand patch development can be divided into three stages,i.e.,formation,expansion,and stabilization,which correspond to the initial,actively developing,and semi-fixed sand patches,respectively.The average dimensions of all sand patch erosional areas were found to be 7.72 m in length,3.91 m in width,and 0.32 m in depth.The actively developing sand patches were the largest,and the initial sand patches were the smallest.Throughout the stage of formation and expansion,the herbaceous community composition changed,and the plant density decreased by more than 50.95%.Moreover,the coverage and height of herbaceous plants decreased in the erosional area and slightly increased in the depositional lobe;and the fine particles and nutrients of soils in the erosional area and depositional lobe showed a decreasing trend.In the stabilization phases of sand patches,the area from the inlet to the bottom of sand patches becomes initially covered with crusts.Vegetation and 0-2 cm surface soil condition improved in the erosional area,but this improvement was not yet evident in the depositional lobe.Factors such as disturbance,climate change,and surface resistance to erosion exert notable influences on the formation and dynamics of sand patches.The results can provide evidence for the future treatment of sand patches and the management of the protection system of Shapotou section of the Baotou-Lanzhou railway. 展开更多
关键词 railway protection system sand patch MORPHOLOGY vegetation characteristic soil property
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Do brood parasitic Common Cuckoos develop brood patches during the breeding season?
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作者 Jun-Seo Go Hae-Ni Kim +3 位作者 Sue-Jeong Jin Myeong-Chan Cha Heesoo Lee Jin-Won Lee 《Avian Research》 SCIE CSCD 2024年第3期363-368,共6页
Many birds develop brood patches on their ventral apterium under hormonal regulation to effectively transmit body heat to eggs during incubation.The developed patch has several characteristics,including de-feathering,... Many birds develop brood patches on their ventral apterium under hormonal regulation to effectively transmit body heat to eggs during incubation.The developed patch has several characteristics,including de-feathering,vascularization,and edema.However,little is known about whether avian brood parasites that do not incubate their eggs exhibit brood patch development during the breeding season.In this study,we measured the size of the ventral apterium in 114 Common Cuckoos(Cuculus canorus)captured in the field throughout the breeding season and examined the appearance of the ventral apterium to confirm the development of brood patches.We also examined whether morphological traits and various factors correlated with the size of the ventral apterium(sternal apterium and abdominal apterium)and how it changed during the breeding season.We found no clear signs of brood patch development in Common Cuckoos captured throughout the breeding season,indicating that they likely did not develop brood patches on the ventral apterium during this period.We also found that ventral apterium size was positively correlated with wing length and body weight.In addition,Common Cuckoos with newly growing feathers on the boundary of the ventral apterium with pteryla were frequently observed as seasons progressed to the end.In conclusion,Common Cuckoos exhibit neither brood patch development nor the vestigial characteristics of ancestral brood patches,except for the growth of feathers on boundary the ventral apterium.Further studies examining brood patches across different groups of avian brood parasites are valuable for enhancing our understanding of the developmental and physiological adaptations of avian brood parasites. 展开更多
关键词 Brood parasitism Brood patch Common Cuckoo Pterylosis Re-feathering Ventral apterium
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Scheme Based on Multi-Level Patch Attention and Lesion Localization for Diabetic Retinopathy Grading
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作者 Zhuoqun Xia Hangyu Hu +4 位作者 Wenjing Li Qisheng Jiang Lan Pu Yicong Shu Arun Kumar Sangaiah 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第7期409-430,共22页
Early screening of diabetes retinopathy(DR)plays an important role in preventing irreversible blindness.Existing research has failed to fully explore effective DR lesion information in fundus maps.Besides,traditional ... Early screening of diabetes retinopathy(DR)plays an important role in preventing irreversible blindness.Existing research has failed to fully explore effective DR lesion information in fundus maps.Besides,traditional attention schemes have not considered the impact of lesion type differences on grading,resulting in unreasonable extraction of important lesion features.Therefore,this paper proposes a DR diagnosis scheme that integrates a multi-level patch attention generator(MPAG)and a lesion localization module(LLM).Firstly,MPAGis used to predict patches of different sizes and generate a weighted attention map based on the prediction score and the types of lesions contained in the patches,fully considering the impact of lesion type differences on grading,solving the problem that the attention maps of lesions cannot be further refined and then adapted to the final DR diagnosis task.Secondly,the LLM generates a global attention map based on localization.Finally,the weighted attention map and global attention map are weighted with the fundus map to fully explore effective DR lesion information and increase the attention of the classification network to lesion details.This paper demonstrates the effectiveness of the proposed method through extensive experiments on the public DDR dataset,obtaining an accuracy of 0.8064. 展开更多
关键词 DDR dataset diabetic retinopathy lesion localization multi-level patch attention mechanism
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Treatment of 198 Cases of Thyroid Nodules with Sanying Capsule Combined with Xiaoying Patch
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作者 Shujing SHI Mingyue YANG +2 位作者 Yue HAO Haihui ZHU Yan QIN 《Medicinal Plant》 2024年第3期56-59,共4页
[Objectives]To observe the clinical efficacy of Sanying capsule combined with Xiaoying Patch in treating thyroid nodule(TN).[Methods]Two groups were treated similarly,with 200 cases in the control group undergoing bas... [Objectives]To observe the clinical efficacy of Sanying capsule combined with Xiaoying Patch in treating thyroid nodule(TN).[Methods]Two groups were treated similarly,with 200 cases in the control group undergoing basic treatment for 12 weeks and 198 cases in the observation group receiving Sanying capsule combined with Xiaoying patches for the same duration.The clinical symptoms,number of nodules,diameter of the largest nodule,and maximum reduction of nodules were observed before and after treatment.A control analysis was performed,and the underlying mechanisms were explored.[Results]The primary symptoms of the observation group exhibited a more favorable improvement than those of the control group.Additionally,the number of nodules decreased,the diameter of the largest nodule decreased,and the maximum reduction of nodules decreased in both groups following treatment.However,the observation group demonstrated a more pronounced improvement than the control group(P<0.05).[Conclusions]The combination of Sanying capsule and Xiaoying patch has been demonstrated to be an effective treatment for TN,with a high degree of reliability in terms of safety. 展开更多
关键词 THYROID NODULE Sanying CAPSULE Xiaoying patch CLINICAL EFFICACY
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Ginger oil-loaded transdermal adhesive patch treats post-traumatic stress disorder
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作者 Xingshuang Song Yizhi Zhang +7 位作者 Ziyan Tang Jing Dai Yanping Wu Guiyu Huang Hong Niu Yaxin Wang Xu Jin Lina Du 《Journal of Traditional Chinese Medical Sciences》 CAS 2024年第3期316-329,共14页
Objective:To find a viable alternative to reduce the number of doses required for the patients with post-traumatic stress disorder(PTSD),and to improve efficacy and patient compliance.Methods: In this study,we used gi... Objective:To find a viable alternative to reduce the number of doses required for the patients with post-traumatic stress disorder(PTSD),and to improve efficacy and patient compliance.Methods: In this study,we used ginger oil,a phytochemical with potential therapeutic properties,to prepare ginger oil patches.High-performance liquid chromatography(HPLC)was used to quantify the main active component of ginger oil,6-gingerol.Transdermal absorption experiments were conducted to optimize the various pressure-sensitive adhesives and permeation enhancers,including their type and concentration.Subsequently,the ginger oil patches were optimized and subjected to content determination and property evaluations.A PTSD mouse model was established using the foot-shock method.The therapeutic effect of ginger oil patches on PTSD was assessed through pathological sections,behavioral tests,and the evaluation of biomarkers such as tumor necrosis factor-α(TNF-α),interleukin-6(IL-6),brain-derived neurotrophic factor(BDNF),and melatonin(MT).Results: The results demonstrated that ginger oil patches exerted therapeutic effects against PTSD by inhibiting inflammatory responses and modulating MT and BDNF levels.Pharmacokinetic experiments revealed that ginger oil patches maintained a stable blood drug concentration for at least one day,addressing the rapid metabolism drawback of 6-gingerol and enhancing its therapeutic efficacy.Conclusions: Ginger oil can be prepared as a transdermal drug patch that meets these requirements,and the bioavailability of the prepared patch is better than that of oral administration.It can improve PTSD with good patient compliance and ease of administration.Therefore,it is a promising therapeutic formulation for the treatment of PTSD. 展开更多
关键词 Post-traumatic stress disorder 6-GINGEROL Pressure sensitive adhesive patch Transdermal delivery
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Unveiling the adaptation strategies of woody plants in remnant forest patches to spatiotemporal urban expansion through leaf trait networks
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作者 Mengping Jian Jingyi Yang 《Forest Ecosystems》 SCIE CSCD 2024年第2期247-254,共8页
Background:With the expansion of urban areas,the remnants of forested areas play a crucial role in preserving biodiversity in urban environments.This study aimed to explore the impact of spatiotemporal urban expansion... Background:With the expansion of urban areas,the remnants of forested areas play a crucial role in preserving biodiversity in urban environments.This study aimed to explore the impact of spatiotemporal urban expansion on the networks of leaf traits in woody plants within remnant forest patches,thereby enhancing our understanding of plant adaptive strategies and contributing to the conservation of urban biodiversity.Methods:Our study examined woody plants within 120 sample plots across 15 remnant forest patches in Guiyang,China.We constructed leaf trait networks (LTNs) based on 26 anatomical,structural,and compositional leaf traits and assessed the effects of the spatiotemporal dynamics of urban expansion on these LTNs.Results and conclusions:Our results indicate that shrubs within these patches have greater average path lengths and diameters than trees.With increasing urban expansion intensity,we observed a rise in the edge density of the LTN-shrubs.Additionally,modularity within the networks of shrubs decreased as road density and urban expansion intensity increased,and increases in the average path length and average clustering coefficient for shrubs were observed with a rise in the composite terrain complexity index.Notably,patches subjected to‘leapfrog’expansion exhibited greater average patch length and diameter than those experiencing edge growth.Stomatal traits were found to have high degree centrality within these networks,signifying their substantial contribution to multiple functions.In urban remnant forests,shrubs bolster their resilience to variable environmental pressures by augmenting the complexity of their leaf trait networks. 展开更多
关键词 Urban remnant forest patch Woody plant Leaf trait network Plant adaptation strategy Spatiotemporal urban expansion
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Deep Global Multiple-Scale and Local Patches Attention Dual-Branch Network for Pose-Invariant Facial Expression Recognition
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作者 Chaoji Liu Xingqiao Liu +1 位作者 Chong Chen Kang Zhou 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第4期405-440,共36页
Pose-invariant facial expression recognition(FER)is an active but challenging research topic in computer vision.Especially with the involvement of diverse observation angles,FER makes the training parameter models inc... Pose-invariant facial expression recognition(FER)is an active but challenging research topic in computer vision.Especially with the involvement of diverse observation angles,FER makes the training parameter models inconsistent from one view to another.This study develops a deep global multiple-scale and local patches attention(GMS-LPA)dual-branch network for pose-invariant FER to weaken the influence of pose variation and selfocclusion on recognition accuracy.In this research,the designed GMS-LPA network contains four main parts,i.e.,the feature extraction module,the global multiple-scale(GMS)module,the local patches attention(LPA)module,and the model-level fusion model.The feature extraction module is designed to extract and normalize texture information to the same size.The GMS model can extract deep global features with different receptive fields,releasing the sensitivity of deeper convolution layers to pose-variant and self-occlusion.The LPA module is built to force the network to focus on local salient features,which can lower the effect of pose variation and self-occlusion on recognition results.Subsequently,the extracted features are fused with a model-level strategy to improve recognition accuracy.Extensive experimentswere conducted on four public databases,and the recognition results demonstrated the feasibility and validity of the proposed methods. 展开更多
关键词 Pose-invariant FER global multiple-scale(GMS) local patches attention(LPA) model-level fusion
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Observing eddy dye patches induced by shear instabilities in the surf zone on a plane beach
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作者 Chunping Ren Nannan Fu +2 位作者 Chong Yu Yuchuan Bai Kezhao Fang 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2024年第3期15-29,共15页
The effects of surf zone eddy generated by alongshore currents on the deformation and transport of dye are still poorly understood,and related tracer release experiments are lacking.Therefore,a tracer release laborato... The effects of surf zone eddy generated by alongshore currents on the deformation and transport of dye are still poorly understood,and related tracer release experiments are lacking.Therefore,a tracer release laboratory experiment was conducted under monochromatic,unidirectional incident waves with a large incident angle(30°)on a plane beach with a 1:100 slope in a large wave basin.A charge-coupled device suspended above the basin recorded the dye patch image.The evolution of eddy dye patch was observed and the transport and diffusion were analyzed based on the collected images.Subsequently,a linear instability numerical model was adopted to calculate the perturbation velocity field at the initial stage.The observation and image processing results show that surf zone eddy patches occurred and were separated from the original dye patches.Our numerical analysis results demonstrate that the structure of the perturbation velocity field is consistent with the experimental observations,and that the ejection of eddy patches shoreward or offshore may be ascribed to the double vortex. 展开更多
关键词 surf zone tracer release experiment evolution of eddy patch shear instability of alongshore currents
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Evaluation of the Efficacy of Auricular Acupoint Pressure Patch Combined with Modified Huangqi Decoction in Treating Diabetic Nephropathy
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作者 Ying Wang 《Journal of Clinical and Nursing Research》 2024年第1期45-50,共6页
Objective:To explore the efficacy of auricular acupoint pressure patch combined with modified Huangqi Decoction in treating diabetic nephropathy.Methods:60 patients with diabetic nephropathy treated in our hospital fr... Objective:To explore the efficacy of auricular acupoint pressure patch combined with modified Huangqi Decoction in treating diabetic nephropathy.Methods:60 patients with diabetic nephropathy treated in our hospital from January 2021 to December 2022 were selected for this study.The patients were randomly divided into two groups using the random number table method,with 30 patients in each group.Among them,the control group was treated with conventional Western medicine,while the experimental group was treated with auricular acupoint pressure patches combined with modified Huangqi Decoction.The patients’fasting blood glucose(FPG),2-hour postprandial blood glucose(2hPG),glycated hemoglobin(HbA1c),urinary protein quantification,urea nitrogen(BUN),serum creatinine(SCr),and other indicators were detected and recorded before and after treatment.Results:Before treatment,there was no statistically significant difference in the FPG,the 2hPG,and the HbA1c between the two groups of patients(P>0.05);after treatment,the FPG,the 2hPG,and the HbA1c of the patients in the experimental group were significantly lower than those in the control group(P<0.05).Before treatment,there was no statistically significant difference in the urinary protein quantification,the BUN,and the SCr between the two groups of patients(P>0.05);after treatment,the urinary protein quantification,BUN,and SCr of the patients in the experimental group were significantly lower than those in the control group(P<0.05).The experimental group showed better improvement in symptoms such as fatigue,backache,and frequency of nocturia(P<0.05).Conclusion:Auricular acupoint pressure patch combined with modified Huangqi Decoction effectively treats diabetic nephropathy and it helps control blood sugar and renal function indicators and improve clinical symptoms,therefore improving the patients’quality of life. 展开更多
关键词 Auricular acupoint pressure patch Modified Huangqi Decoction Diabetic nephropathy
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A Simple Egg Membrane Patch Bridging Method for Repairing Tympanic Membrane Perforation
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作者 Xing Huang Xuping Wang +2 位作者 Bin Li Lumei Shao Ping Li 《Journal of Clinical and Nursing Research》 2024年第8期264-269,共6页
Objective:To analyze the clinical effect of a simple egg membrane patch bridging method in repairing tympanic membrane perforation.Methods:A total of 93 tympanic membrane perforation patients admitted to the hospital ... Objective:To analyze the clinical effect of a simple egg membrane patch bridging method in repairing tympanic membrane perforation.Methods:A total of 93 tympanic membrane perforation patients admitted to the hospital between September 2022 and October 2023 were selected and divided into two groups according to the random number table method.The control group implemented the conventional treatment(n=46 cases),and the patch group adopted the simple egg membrane patch bridging method(n=47 cases).The healing rate of the tympanic membrane,the air-bone gap,the air conduction hearing threshold,the dry ear rate,and the incidence of complications in both groups were compared before and after treatment.Results:The healing rate of the tympanic membrane in the patch group was significantly higher than that of the control group(95.75%vs.76.09%),with P<0.05;there was no difference in the air-bone gap and air conduction hearing threshold levels between the two groups before treatment(P>0.05),and the hearing indexes of the patch group were significantly lower than those of the control group 3 months after treatment(P<0.05);the dry ear rate in the patch group was significantly higher than that of the control group after treatment(85.11%vs.67.39%),and the total incidence of complications was also significantly lower than that of the control group(6.38%vs.21.74%),with P<0.05.Conclusion:The simple egg membrane patch bridging method is effective in repairing tympanic membrane perforation,which can effectively improve patients’hearing levels and reduce the occurrence of post-treatment complications.Thus,it is worth popularizing and applying in the clinic. 展开更多
关键词 Egg membrane patch bridging method Tympanic membrane perforation Hearing level
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Bézier曲线与Said-Ball曲线的递归转换算法 被引量:3
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作者 陈凌钧 骆岩林 +1 位作者 童若锋 汪国昭 《计算机辅助设计与图形学学报》 EI CSCD 北大核心 2001年第3期264-266,共3页
根据 Bézier曲线与 Said- Ball曲线的统一表示 ,给出了 Bézier曲线与 Said-
关键词 BEZIER曲线 BALL曲线 said-ball曲线 曲线递归转换算法 CAD
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带双参数的五次Said-Ball型曲线曲面 被引量:5
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作者 陈辉 王成伟 《北京服装学院学报(自然科学版)》 CAS 2014年第2期67-75,共9页
文章构造了1组带有2个形状参数α、β的五次Said-Ball型基函数,它是四次Said-Ball基函数的扩展.基于Said-Ball型基函数定义了带双参数的Said-Ball型曲线和张量积曲面,这种曲线不仅具有四次Ball曲线的特性,还能够实现五次Said-Ball曲线... 文章构造了1组带有2个形状参数α、β的五次Said-Ball型基函数,它是四次Said-Ball基函数的扩展.基于Said-Ball型基函数定义了带双参数的Said-Ball型曲线和张量积曲面,这种曲线不仅具有四次Ball曲线的特性,还能够实现五次Said-Ball曲线到四次Bézier曲线的过渡.文中分析了基函数及曲线的性质和2个形状参数的几何意义;给出了2条Said-Ball型曲线的G0、G1、G2连续拼接条件;最后以实例表明构造的新曲线为曲线曲面造型提供了一种有效方法. 展开更多
关键词 said-ball曲线 BÉZIER曲线 形状参数 曲线设计 连续性
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Said-Ball曲线的降多阶逼近 被引量:1
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作者 唐烁 张莉 《合肥工业大学学报(自然科学版)》 CAS CSCD 2004年第6期677-681,共5页
文章首先给出了Said-Ball曲线的一种降多阶逼近方法,它主要考察了原曲线与降阶曲线之间在最小二乘范数下的距离函数,通过距离函数取最小值,从而得到降阶曲线控制顶点的显式表示式。该方法还考虑了原曲线与降阶曲线在两端点处分别达到(r... 文章首先给出了Said-Ball曲线的一种降多阶逼近方法,它主要考察了原曲线与降阶曲线之间在最小二乘范数下的距离函数,通过距离函数取最小值,从而得到降阶曲线控制顶点的显式表示式。该方法还考虑了原曲线与降阶曲线在两端点处分别达到(r,s)阶连续的情形(r≥0,s≥0),给出了降阶误差界的估计及数值例子。 展开更多
关键词 said-ball曲线 降多阶 升阶 控制顶点
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Said-Ball曲线的细分算法 被引量:2
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作者 夏成林 崔靖 《泰州职业技术学院学报》 2007年第4期67-70,共4页
设实数c(0<c<1)将广义Said-Ball曲线r(u),0≤u≤1分为两段r[0,c](u)=r[cu]和r[c,1](u)=r(c+(1-c)u),0≤u≤1.利用对偶泛函,给出用显式表示的Said-Ball曲线的细分算法(细分矩阵)。所给出的显示细分矩阵有利于曲线的生成与合并方面... 设实数c(0<c<1)将广义Said-Ball曲线r(u),0≤u≤1分为两段r[0,c](u)=r[cu]和r[c,1](u)=r(c+(1-c)u),0≤u≤1.利用对偶泛函,给出用显式表示的Said-Ball曲线的细分算法(细分矩阵)。所给出的显示细分矩阵有利于曲线的生成与合并方面的研究。 展开更多
关键词 said-ball曲线 对偶泛函 细分矩阵
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基于最小二乘法的张量积Said-Ball曲面降多阶逼近 被引量:1
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作者 张莉 唐烁 《大学数学》 北大核心 2006年第5期67-72,共6页
给出张量积Said-Ball曲面降多阶逼近的一种方法.该方法根据原张量积Said-Ball曲面Pn,m(u,v)与降多阶张量积Said-Ball曲面Qn1,m1(u,v)(n1≤n-1,m1≤m-1)在最小二乘范数下的距离函数在单位正方形[0,1]×[0,1]上取最小值,从而得到了用... 给出张量积Said-Ball曲面降多阶逼近的一种方法.该方法根据原张量积Said-Ball曲面Pn,m(u,v)与降多阶张量积Said-Ball曲面Qn1,m1(u,v)(n1≤n-1,m1≤m-1)在最小二乘范数下的距离函数在单位正方形[0,1]×[0,1]上取最小值,从而得到了用矩阵表示的降多阶张量积Said-Ball曲面Qn1,m1(u,v)的控制顶点{qij}in1=,0,m1j=0的显示表示式.在降多阶过程中,分别考虑了带角点高阶插值条件和不带角点插值条件的情形.文末附有数值例子,并将本文方法与参考文献(9)的方法做了比较. 展开更多
关键词 张量积said-ball曲面 降多阶 角点插值
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带双形状参数的拟六次Said-Ball曲线及其在服装造型中的应用 被引量:1
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作者 王成伟 张卷美 《北京电子科技学院学报》 2019年第1期74-79,共6页
为了满足曲线在造型设计上要求,构造出一组拟六次Said-Ball基函数,该组基函数含有双形状参数α、β,将它们的性质进行了讨论。定义了由拟六次Said-Ball基函数生成拟六次Said-Ball曲线,该曲线带有两个形状参数,可以改变曲线的形状;讨论... 为了满足曲线在造型设计上要求,构造出一组拟六次Said-Ball基函数,该组基函数含有双形状参数α、β,将它们的性质进行了讨论。定义了由拟六次Said-Ball基函数生成拟六次Said-Ball曲线,该曲线带有两个形状参数,可以改变曲线的形状;讨论了两段曲线拼接的条件。应用例子进一步说明该方法是实用的,应用前景非常广泛。 展开更多
关键词 曲线设计 said-ball曲线 形状参数 连续性
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三角域上Said-Ball曲面与Bézier曲面之间一种新的转换算法
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作者 江平 邬弘毅 檀结庆 《中国科学技术大学学报》 CAS CSCD 北大核心 2004年第5期543-548,共6页
通过引入一族三角域上带位置参数H的广义Ball基和广义Ball曲面 ,并利用相邻两曲面的基函数之间的关系 ,给出三角域上Said Ball曲面与B啨zier曲面之间的一种新的递归转换算法 .该算法计算量小 。
关键词 三角域 广义Ball基 位置参数H said-ball曲面 BÉZIER曲面
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