检索结果-南通市图书馆

Tsinghua Science and Technology 2023年第3期28卷 566-579页

作者： Wenfei Hu sen yin Liang Wang Chunxue Liu Zhikai Wang Zuochang Ye Yan Wang School of Integrated Circuits Tsinghua UniversityBeijing 100084China Beijing Microelectronics Technology Institute(BMTI) Beijing 100076China Beijing Innovation Center for Future Chips Tsinghua UniversityBeijing 100084China Beijing National Research Center for Information Science and Technology Tsinghua UniversityBeijing 100084China

Transient sensitivity analysis aims to obtain the gradients of objective functions(circuit performance)with respect to design or variation parameters in a simulator,which can be widely used in yield analysis and circuit optimization,among others.However,the traditional method has a computational complexity of O(N^(2))for objective functions containing circuit states at N time points.The computational complexity is too expensive for large N,especially in time-frequency transform.This paper proposes a many-time-point sensitivity method to reduce the computational complexity to O(N)in multiparameter many-time-point cases.The paper demonstrates a derivation process that improves efficiency by weighting the transfer chain and multiplexing the backpropagation process.We also proposed an early-stop method to improve efficiency further under the premise of ensuring accuracy.The algorithm enables sensitivity calculation of performances involving thousands of time points,such as signal-to-noise and distortion ratio and total harmonic distortion,with significant speed improvements.

关键词： adjoint sensitivity Fourier transformation transient analysis many time point sensitivity(MTPS) early-stop

Building a Post-Layout Simulation Performance Model with Global Mapping Model Fusion Technique

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Tsinghua Science and Technology 2022年第3期27卷 512-525页

作者： Zhikai Wang Wenfei Hu sen yin Ruitao Wang Jian Zhang Yan Wang Zuochang Ye School of Integrated Circuits Tsinghua UniversityBeijing 100084China the Beijing Innovation Center for Future Chips(ICFC) Beijing National Research Center for Information Science and Technology(NRist)and School of Integrated CircuitsTsinghua UniversityBeijing 100084China

Building a post-layout simulation performance model is essential in closing the loop of analog circuits, but it is a challenging task because of the high-dimensional space and expensive simulation cost. To facilitate efficient modeling, this paper proposes a Global Mapping Model Fusion(GMMF) technique. The key idea of GMMF is to reuse the schematic-level model trained by the Artificial Neural Network(ANN) algorithm, and combine it with few mapping coefficients to build the post-simulation model. Furthermore, as an efficient global optimization algorithm,differential evolution is applied to determine the optimal mapping coefficients with few samples. In GMMF, only a small number of mapping coefficients are unknown, so the number of post-layout samples needed is significantly reduced. To enhance practical utility of the proposed GMMF technique, two specific mapping relations, i.e., linear or weakly no-linear and nonlinear, are carefully considered in this paper. We conduct experiments on two topologies of two-stage operational amplifier and comparator in different commercial processes. All the simulation data for modeling are obtained from a parametric design framework. A more than 5 runtime speedup is achieved over ANN without surrendering any accuracy.

关键词： post-layout simulation performance model Global Mapping Model Fusion(GMMF) Artificial Neural Network(ANN) few mapping coefficients differential evolution

Design of ultrasonic elliptical vibration cutting system for tungsten heavy alloy

在线全文

学校读者我要写书评

暂无评论

Frontiers of Mechanical Engineering 2022年第4期17卷 163-180页

作者： sen yin Yan BAO Yanan PAN Zhigang DONG Zhuji JIN Renke KANG Key Laboratory for Precision and Non-traditional Machining Technology of the Ministry of Education School of Mechanical EngineeringDalian University of TechnologyDalian 116024China

Nanoscale surface roughness of tungsten heavy alloy components is required in the nuclear industry and precision instruments.In this study,a high-performance ultrasonic elliptical vibration cutting(UEVC)system is developed to solve the precision machining problem of tungsten heavy alloy.A new design method of stepped bending vibration horn based on Timoshenko’s theory is first proposed,and its design process is greatly simplified.The arrangement and working principle of piezoelectric transducers on the ultrasonic vibrator using the fifth resonant mode of bending are analyzed to realize the dual-bending vibration modes.A cutting tool is installed at the end of the ultrasonic vibration unit to output the ultrasonic elliptical vibration locus,which is verified by finite element method.The vibration unit can display different three-degree-of-freedom(3-DOF)UEVC characteristics by adjusting the corresponding position of the unit and workpiece.A dual-channel ultrasonic power supply is developed to excite the ultrasonic vibration unit,which makes the UEVC system present the resonant frequency of 41 kHz and the maximum amplitude of 14.2μm.Different microtopography and surface roughness are obtained by the cutting experiments of tungsten heavy alloy hemispherical workpiece with the UEVC system,which validates the proposed design’s technical capability and provides optimization basis for further improving the machining quality of the curved surface components of tungsten heavy alloy.

关键词： tungsten heavy alloy ultrasonic elliptical vibration cutting Timoshenko’s theory resonant mode of bending finite element method

Hole quality in longitudinal–torsional coupled ultrasonic vibration assisted drilling of carbon fiber reinforced plastics

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Mechanical Engineering 2020年第4期15卷 538-546页

作者： Guofeng MA Renke KANG Zhigang DONG sen yin Yan BAO Dongming GUO Key Laboratory for Precision and Non-Traditional Machining of Ministry of Education Dalian University of TechnologyDalian 116024China

Carbon fiber reinforced plastic (CFRP) composites are extremely attractive in the manufacturing of structural and functional components in the aircraft manufacturing field due to their outstanding properties, such as good fatigue resistance, high specific stiffness/strength, and good shock absorption. However, because of their inherent anisotropy, low interlamination strength, and abrasive characteristics, CFRP composites are considered difficult-to-cut materials and are prone to generating serious hole defects, such as delamination, tearing, and burrs. The advanced longitudinal–torsional coupled ultrasonic vibration assisted drilling (LTC-UAD) method has a potential application for drilling CFRP composites. At present, LTC-UAD is mainly adopted for drilling metal materials and rarely for CFRP. Therefore, this study analyzes the kinematic characteristics and the influence of feed rate on the drilling performance of LTC-UAD. Experimental results indicate that LTC-UAD can reduce the thrust force by 39% compared to conventional drilling. Furthermore, LTC-UAD can decrease the delamination and burr factors and improve the surface quality of the hole wall. Thus, LTC-UAD is an applicable process method for drilling components made with CFRP composites.

关键词： longitudinal–torsional coupled ultrasonically drilling CFRP thrust force hole quality

Targeting mitochondrial transcription factor A sensitizes pancreatic cancer cell to gemcitabine

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

国际肝胆胰疾病杂志:英文版 2023年第5期22卷 519-527页

作者： Wei Wang Chun-Fan Jiang Hai-sen yin Shan Gao Bao-Ping Yu Department of Gastroenterology Renmin Hospital of Wuhan UniversityWuhan 430060China Department of Gastroenterology Xiangyang Central HospitalAffiliated Hospital of Hubei University of Arts and ScienceXiangyang 441021China Department of Pathology Xiangyang Central HospitalAffiliated Hospital of Hubei University of Arts and ScienceXiangyang 441021China

Background:The survival of pancreatic cancer cells,particularly cancer stem cells which are responsible for tumor relapse,depends on mitochondrial function.Mitochondrial transcription factor A(TFAM)is critical for the regulation of mitochondrial DNA and thus mitochondrial function.However,the possible involvement of TFAM in pancreatic cancer is unknown.Methods:Human samples were obtained from pancreatic cancers and their adjacent tissues;human pancreatic cell lines were cultured in RPMI1640 medium.TFAM expressions in pancreatic tissues and cultured cells were determined using immunohistochemistry,ELISA,and reverse transcription polymerase chain reaction(RT-PCR).The effect of TFAM on cell growth,migration,colony formation and apoptosis were evaluated.Mitochondrial biogenesis in pancreatic cancer and normal cells were examined.Results:The majority of pancreatic cancer tissues exhibited higher TFAM expression compared to the adjacent counterparts.Consistently,TFAM mRNA and protein levels were higher in pancreatic cancer cell lines than in immortalized normal pancreatic epithelial cells.There was no difference on TFAM level between gemcitabine-sensitive and resistant pancreatic cancer cells.Functional analysis demonstrated that TFAM overexpression activated pancreatic normal and tumor cells whereas TFAM inhibition effectively inhibited the growth of pancreatic cancer cells.TFAM inhibition enhanced gemcitabine’s cytotoxicity and suppressed growth,anchorage-independent colony formation and survival of gemcitabine-resistant pancreatic cancer cells.Mechanistic studies showed that TFAM inhibition resulted in remarkable mitochondrial dysfunction and energy crisis followed by oxidative stress.The basal mitochondrial biogenesis level correlated well with TFAM level in pancreatic cancer cells.Conclusions:TFAM played essential roles in pancreatic cancer via regulating mitochondrial functions which highlighted the therapeutic value of inhibiting TFAM to overcome gemcitabine resistance.

关键词： TFAM Mitochondrial respiration and biogenesis Pancreatic cancer Gemcitabine

基于WebGL的数字露头可视化表征与识别系统:以无人机倾斜摄影依奇克里克剖面为例

在线全文

学校读者我要写书评

暂无评论

科学技术与工程 2024年第11期24卷 4633-4642页

作者：董志成陈恭洋印森林朱柏宇长江大学录井技术与工程研究院荆州434000

为满足地质工作者对野外露头表征数据分析的需求,针对现有的软件在三维可视化、跨设备、跨平台性及易操作性等方面的不足。基于WebGL开发了地质三维数字露头可视化平台。首先设计了平台的开发框架及实现路线,以Cesium为框架为基础,通过... 详细信息

为满足地质工作者对野外露头表征数据分析的需求,针对现有的软件在三维可视化、跨设备、跨平台性及易操作性等方面的不足。基于WebGL开发了地质三维数字露头可视化平台。首先设计了平台的开发框架及实现路线,以Cesium为框架为基础,通过无人机倾斜摄影进行数据采集,结合U-net算法对地质数据进行分割和分析,实现了数据在跨平台、跨设备上的可视化展示和交互。具体应用中,U-net算法可自动识别和标记地质露头的地层特征和结构,可视化平台则针对识别出的特征提供丰富的测量和标绘工具,更加直观地展示露头信息,有助于地质勘探者更快捷、更全面地理解野外地质条件,提高露头表征数据的分析效率和易用性。仿真分析实例表明,验证了基于U-net算法的分割结果在露头表征和地层分析方面取得了较高的精度和可靠性,该可视化平台将会极大提升野外露头表征的分析效率与易用性,对加快数字中国、智慧地质的建设具有极高的应用价值。

关键词： WebGL 数字露头 Cesium 可视化平台语义分割倾斜摄影

Clivus-involved immunoglobulin G4 related hypertrophic pachymeningitis mimicking meningioma:A case report

在线全文

学校读者我要写书评

暂无评论

World Journal of Clinical Cases 2022年第18期10卷 6269-6276页

作者： Yang Yu Liang Lv sen-Lin yin Cheng Chen Shu Jiang Pei-Zhi Zhou Department of Neur-osurgery West China HospitalSichuan UniversityChengdu 610041Sichuan ProvinceChina

BACKGROUND Immunoglobulin G4 related disease(Ig G4-RD)is a fibroinflammatory disease with markedly elevated serum Ig G4 levels and fibrous tissue proliferation,accompanied by numerous plasma cells.Ig G4 related hypertrophic pachymeningitis(Ig G4-RHP)is relatively rare and indistinguishable from other phymatoid diseases before the operation.The risk of long-term immunosuppression needs to be balanced with disease activity.CASE SUMMARY A 40-year-old man presented with headache and bilateral abducent paralysis.He was also diagnosed with pulmonary tuberculosis 10 years ago and was on regular treatment for the same.Before the operation and steroid therapy,the patient was suspected of having tubercular meningitis at a local hospital.A clivus lesion was found via brain magnetic resonance imaging(MRI)at this presentation.He was preliminarily diagnosed with meningioma and underwent Gamma Knife Surgery.Transnasal endoscopic resection was performed to treat deterioration of nerve function.Postoperative pathologic examination suggested Ig G4-RD.Moreover,the serum Ig G4 was elevated at 1.90 g/L(reference range:0.035-1.500 g/L).After steroid therapy for 2 mo,the lesion size diminished on MRI,and the function of bilateral abducent nerves recovered.CONCLUSION Ig G4-RHP is relatively rare and indistinguishable before the operation.Elevated serum Ig G4 levels and imaging examination help in the diagnosis of Ig G4-RHP.Surgery is necessary when lesions progress and patients start to develop cranial nerve function deficit.

关键词： Immunoglobulin G4 related disease Hypertrophic pachymeningitis Immu-noglobulin G4 related hypertrophic pachymeningitis Clivus Case report

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

基于机器学习的传感网核心节点漏洞检测仿真

计算机仿真 2024年第3期41卷 410-414页

作者：徐寅森李红艳张子栋商丘学院计算机工程学院河南商丘476000 集美大学计算机工程学院福建厦门361021

传感网的核心节点具有能量受限、难补给的特点,导致节点轮休时易出现的覆盖漏洞问题,造成传感网监测盲区。为此提出基于机器学习的传感网核心节点漏洞检测方法。利用支持向量机树形多分类器获取核心节点的位置。采取主成分分析法提取核... 详细信息

传感网的核心节点具有能量受限、难补给的特点,导致节点轮休时易出现的覆盖漏洞问题,造成传感网监测盲区。为此提出基于机器学习的传感网核心节点漏洞检测方法。利用支持向量机树形多分类器获取核心节点的位置。采取主成分分析法提取核心节点特征,将其输入到LSTM长短记忆神经网络模型中,并利用滑动窗口与哈希函数训练漏洞检测分类模型,完成传感网核心节点的漏洞检测。实验结果表明,研究方法检测传感网漏洞时平均耗时为13.6ms,检测率和准确率均可高达95%,计算得到性能消耗低于10%,90%的用户响应时间均在50ms以内。

关键词：支持向量机树型多分类器特征提取主成分分析线性哈希函数欧氏距离

在线全文

学校读者我要写书评

暂无评论

蜂窝移动网络大数据聚类异常挖掘方法仿真

计算机仿真 2024年第2期41卷 406-409,414页

作者：李红艳徐寅森张子栋商丘学院计算机工程学院河南商丘476000 集美大学计算机工程学院福建厦门361021

蜂窝移动网络可提供话音、数据、视频图像等业务,具有终端移动性、越区切换和跨本地网自动漫游功能,因此上述网络环境中的数据为移动宽带数据流量,数据量巨大,并一直处于自更新状态,导致其聚类过程中易产生异常数据。针对上述问题,提出... 详细信息

蜂窝移动网络可提供话音、数据、视频图像等业务,具有终端移动性、越区切换和跨本地网自动漫游功能,因此上述网络环境中的数据为移动宽带数据流量,数据量巨大,并一直处于自更新状态,导致其聚类过程中易产生异常数据。针对上述问题,提出蜂窝移动网络大数据聚类异常挖掘方法。根据蜂窝移动网络的结构、数据存储结构以及数据特征,对数据属性聚类,并提取异常数据的弱相关特征值。基于以上情况,将提取的弱相关特征值输入至聚类器中,挖掘蜂窝移动网络大数据的异常数据。实验结果表明,蜂窝移动网络大数据量逐渐增多时,研究方法的挖掘准确性仍能保持在98.5%以上,耗时可控制4ms以内,漏检率始终低于1%,误检率不超过2%。以上所得数据说明该方法的应用可靠性更优。

关键词：蜂窝移动网络大数据异常挖掘方法数据聚类弱相关特征

A Non-canonical Excitatory PV RGC–PV SC Visual Pathway for Mediating the Looming-evoked Innate Defensive Response

在线全文

学校读者我要写书评

暂无评论

Neuroscience Bulletin 2024年第3期40卷 310-324页

作者： Man Yuan sen Jin Gao Tan Siyuan Song Yizong Liu Huadong Wang yin Shen Eye Center Renmin Hospital of Wuhan UniversityWuhan UniversityWuhan430060China The Brain Cognition and Brain Disease Institute Shenzhen Key Laboratory of Viral Vectors for BiomedicineShenzhen Institute of Advanced TechnologyChinese Academy of Sciences(CAS)Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research InstitutionsNational Medical Products Administration Key Laboratory for Research and Evaluation of Viral Vector Technology in Cell and Gene Therapy Medicinal ProductsShenzhen Key Laboratory of Quality Control Technology for Virus-Based TherapeuticsGuangdong Provincial Medical Products AdministrationShenzhen518055China Jan and Dan Duncan Neurological Research Institute Baylor College of MedicineHouston77030USA State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Key Laboratory of Magnetic Resonance in Biological SystemsWuhan Center for Magnetic ResonanceInnovation Academy for Precision Measurement Science and TechnologyCASWuhan430071China Frontier Science Center of Immunology and Metabolism Medical Research InstituteWuhan UniversityWuhan430071China

Parvalbumin-positive retinal ganglion cells(PV+RGCs)are an essential subset of RGCs found in various species.However,their role in transmitting visual information remains unclear.Here,we characterized PV+RGCs in the retina and explored the functions of the PV+RGC-mediated visual pathway.By applying multiple viral tracing strategies,we investigated the downstream of PV+RGCs across the whole brain.Interestingly,we found that the PV+RGCs provided direct monosynaptic input to PV+excitatory neurons in the superficial layers of the superior colliculus(SC).Ablation or suppression of SC-projecting PV+RGCs abolished or severely impaired the flight response to looming visual stimuli in mice without affecting visual acuity.Furthermore,using transcriptome expression profiling of individual cells and immunofluorescence colocalization for RGCs,we found that PV+RGCs are predominant glutamatergic neurons.Thus,our findings indicate the critical role of PV+RGCs in an innate defensive response and suggest a non-canonical subcortical visual pathway from excitatory PV+RGCs to PV+SC neurons that regulates looming visual stimuli.These results provide a potential target for intervening and treating diseases related to this circuit,such as schizophrenia and autism.

关键词： Parvalbumin-positive retinal ganglion cell Innate fear Superior colliculus Excitatory-excitatory neuronal connection Looming-evoked defensive response Subcortical pathway