检索结果-南通市图书馆

A polymeric piezoelectric MEMS accelerometer with high sensitivity,low noise density,and an innovative manufacturing approach

在线全文

学校读者我要写书评

暂无评论

Microsystems & Nanoengineering 2023年第6期9卷 149-164页

作者： Chang ge Edmond Cretu The Department of Electrical and Computer Engineering The University of British ColumbiaVancouverCanada

The piezoelectric coupling principle is widely used(along with capacitive coupling and piezoresistive coupling)for MEMS *** MEMS accelerometers are used primarily for vibration *** piezoelectric MEMS accelerometers offer the merits of heavy-metal-free structure material and simple microfabrication *** importantly,polymeric piezoelectric MEMS accelerometers may be the basis of novel applications,such as fully organic inertial sensing microsystems using polymer sensors and organic integrated *** paper presents a novel polymer piezoelectric MEMS accelerometer design using PVDF films.A simple and rapid microfabrication flow based on laser micromachining of thin films and 3D stereolithography was developed to fabricate three samples of this *** proof-of-concept experiments,the design achieved a sensitivity of 21.82 pC/g(equivalent open-circuit voltage sensitivity:126.32 mV/g),a 5%flat band of 58.5 Hz,and a noise density of 6.02µg/√***,this design rivals state-of-the-art PZT-based counterparts in charge sensitivity and noise density,and it surpasses the performance capabilities of several commercial MEMS ***,this design has a 10-times smaller device area and a 4-times larger flat band than previous state-of-the-art organic piezoelectric MEMS *** experimentally validated performance metrics demonstrate the promising application potential of the polymeric piezoelectric MEMS accelerometer design presented in this article.

关键词： piezoelectric accelerometer noise

Optimal reorientation of underactuated spacecraft using genetic algorithm with wavelet approximation

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2009年第4期25卷 547-553页

作者： Xinsheng ge Liqun Chen College of Mechanical & Electrical Engineering Beijing Information Science & Technology University 100192 Beijing China Department of Mechanical Shanghai University 200072 Shanghai China

The optimal attitude control of an underactuated spacecraft is investigated in this paper. The flywheels of the spacecraft can somehow only provide control inputs in two independent directions. The dynamic equations are formulated for the spacecraft under a nonholonomic constraint resulting from the constant time-rate of the total angular momentum of the system. The reorientation of such underactuated spacecraft is transformed into an optimal control problem. A genetic algorithm is proposed to derive the control laws of the two flywheels angle velocity inputs. The control laws are approximated by the discrete orthogonal wavelets. The numerical simulations indicate that the genetic algorithm with the wavelet approximation is an effective approach to deal with the optimal reorientation of underactuated spacecraft.

关键词： Underactuated spacecraft Reorientation Attitude control genetic algorithm Wavelet

From solar terms to medical terms(PartⅡ):Some implications for traditional Chinese Medicine

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2017年第11期60卷 2051-2058页

作者： SHI Jie CHEN ge Department of Pharmacy Municipal Hospital of QingdaoQingdao 266000China College of Information Science and Engineering Ocean University of ChinaQingdao 266100China Laboratory for Regional Oceanography and Numerical Modeling Qingdao National Laboratory for Marine Science and TechnologyQingdao 266200China

In the traditional Chinese Medicine(TCM), the timing of performing the treatment during the year is always an important factor for maximizing its effectiveness. Based on over half a century of observational and reanalysis data, a modified calendric system, named the Twenty-four Medical Terms(24-MTs), has been established for China's Mainland following a systematic calibration and geographical adjustment of the classic Twenty-four Solar Terms(24-STs). In view of "adapting the human body to the changing universe", a core philosophy of the TCM, this improved medical calendar is expected to make a significant contribution to the development of precise Chinese Medicine in the big data era. Specifically, two maps of localized timings for the so-called Triple-Fu(TF) and Triple-Jiu(TF) defined using a joint heat index of air temperature and relative humidity are created as an alternative to the two nationwide unified timings representing the warmest and coldest periods of the year. These location-specific medical calendars, with a maximum regional time shift of one week for TJ and a systematic advancing of 3.6–28.2 days for TF in China's Mainland, are thought to be clinically useful for carrying out precise TCM such as"treating winter deceases in summer". In addition, similar maps of localized timings for peak spring and peak autumn defined as the days of fastest warming and cooling around the years are generated for China's Mainland, so as to provide a helpful guidance for practicing season(ST/MT) related and geographically dependent precise health care in the context of "born in spring, grow in summer, harvest in autumn, and preserve in winter", which is a key ideology in the TCM.

关键词： Solar terms Medical terms Traditional Chinese Medicine

Response of turbulent enstrophy to sudden implementation of spanwise wall oscillation in channel flow

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2017年第8期38卷 1159-1170页

作者： Mingwei ge Guodong JIN School of Renewable Energy North China Electric Power University State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of Sciences

The response of turbulent enstrophy to a sudden implementation of spanwise wall oscillation（SWO） is studied in a turbulent channel flow via direct numerical simulation. In the beginning of the application of SWO, a significant correlation is formed between ω′yand ω′z. A transient growth of turbulent enstrophy occurs, which directly enhances turbulent dissipation and drifts the turbulent flow towards a new lower-drag condition. Afterwards, the terms related to the stretching of vorticity（ωx, ω′y, and ωz）,the inclination of ω′yby ？w/？y, the turn of z by ？v′/？z, and the horizontal shear of z by ？w′/？x are suppressed due to the presence of SWO, leading to attenuation of the turbulent enstrophy.

关键词： turbulent sudden oscillation stretching dissipation turbulence vorticity averaged suppressed Reynolds

Robots Exclusion and Guidance Protocol

在线全文

学校读者我要写书评

暂无评论

Tsinghua Science and Technology 2016年第6期21卷 643-659页

作者： Dajie ge Zhijun Ding Department of Computer Science and Technology Tongji University

With the rapid development of the Internet, general-purpose web crawlers have increasingly become unable to meet people＇s individual needs as they are no longer efficient enough to fetch deep web pages. The presence of several deep web pages in the websites and the widespread use of Ajax make it difficult for generalpurpose web crawlers to fetch information quickly and efficiently. On the basis of the original Robots Exclusion Protocol（REP）, a Robots Exclusion and Guidance Protocol（REGP） is proposed in this paper, by integrating the independent scattered expansions of the original Robots Protocol developed by major search engine *** protocol expands the file format and command set of the REP as well as two labels of the Sitemap *** our protocol, websites can express their aspects of requirements for restrictions and guidance to the visiting crawlers, and provide a general-purpose fast access of deep web pages and Ajax pages for the crawlers,and facilitates crawlers to easily obtain the open data on websites effectively with ease. Finally, this paper presents a specific application scenario, in which both a website and a crawler work with support from our protocol. A series of experiments are also conducted to demonstrate the efficiency of the proposed protocol.

关键词： deep web Ajax crawler protocol

Visual tracking using discriminative representation with l2 regularization

在线全文

学校读者我要写书评

暂无评论

Frontiers of Computer Science 2019年第1期13卷 199-211页

作者： Haijun WANG Hongjuan ge College of Civil Aviation Nanjing University of Aeronautics and AstronauticsNanjing 211106China Aviation Information Technology Research and Development Center Binzhou UniversityBinzhou 256603China

In this paper,we propose a novel visual tracking method using a discriminative representation under a Bayesian ***,we exploit the histogram of gradient (HOG)to generate the texture features of the target templates and ***,we introduce a novel discriminative representation and l2-regularized least squares method to solve the proposed representation *** proposed model has a closed-form solution and very high computational ***,a novel likelihood function and an update scheme considering the occlusion factor are adopted to improve the tracking performance of our proposed method. Both qualitative and quantitative evaluations on 15 challenging video sequences demonstrate that our method can achieve more robust tracking results in terms of the overlap rate and center location error.

关键词： visual tracking discriminative representation Bayesian framework closed-form solution

Meridional deflection of global eddy propagation derived from tandem altimetry: Mechanism and implication

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Earth Sciences 2024年第3期67卷 811-825页

作者： ge CHEN Xiaoyan CHEN Frontiers Science Center for Deep Ocean Multispheres and Earth System School of Marine TechnologyOcean University of ChinaQindao 266100China Laboratory for Regional Oceanography and Numerical Modeling Laoshan LaboratoryQindao 266237China

A common view on meridional deflection of eddy propagation is poleward for cyclones and equatorward for anticyclones. This widely accepted polarity-sensitive pattern has been increasingly undermined given that it is systematically violated on both zonal and regional scales as recently reported. Here, we approach the problem by exploring these violations in terms of eddy effects of spatiotemporal geostrophy, thermal fading, and flow dragging, yielding the following main conclusions.(1) The polarity-dependent deflection discrepancy is a pseudo feature resulting from a biased fit to the normalized eddy tracks which are spatially asymmetric(though azimuthally symmetric) between the two signs;Instead, the primary pattern of eddy deflection appears to be geographically correlated and polarity independent.(2) geostrophic adjustment plays a critical role in defining the meridional movement of an eddy. Specifically, a consistent poleward(equatorward) trajectory bending of spatially(temporally) ageostrophic eddies is observed irrespective of their polarity.(3) The mechanism of eddy deflection is also determined by its zonal propagation direction. Westward propagating eddies are substantially affected by thermal fading, while opposite ones by flow dragging. A realistic and comprehensive understanding of eddy deflection mechanisms serves as a significant contribution to the prediction of eddy trajectory, and the protection of ocean environment.

关键词： Mesoscale eddies Eddy propagation Eddy meridional deflection Satellite observation geostrophic adjustment

Hierarchical deep hashing for image retrieval

在线全文

学校读者我要写书评

暂无评论

Frontiers of Computer Science 2017年第2期11卷 253-265页

作者： ge SONG Xiaoyang TAN College of Computer Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 211106 China Collaborative Innovation Center of Novel Software Technology and Industrialization Nanjing 211106 China

We present a new method to generate efficient multi-level hashing codes for image retrieval based on the deep siamese conv01utional neural network （DSCNN）. Con- ventional deep hashing methods trade off the capability of capturing highly complex and nonlinear semantic informa- tion of images against very compact hash codes, usually lead- ing to high retrieval efficiency but with deteriorated accuracy. We alleviate the restrictive compactness requirement of hash codes by extending them to a two-level hierarchical coding scheme, in which the first level aims to capture the high-level semantic information extracted by the deep network using a rich encoding strategy, while the subsequent level squeezes them to more global and compact codes. At running time, we adopt an attention-based mechanism to select some of its most essential bits specific to each query image for retrieval instead of using the full hash codes of the first level. The attention-based mechanism is based on the guides of hash codes generated by the second level, taking advantage of both local and global properties of deep features. Experimental re- suits on various popular datasets demonstrate the advantages of the proposed method compared to several state-of-the-art methods.

关键词： image retrieval deep hashing hierarchical deep hashing

Enhancing manual P-phase arrival detection and automatic onset time picking in a noisy microseismic data in underground mines

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2018年第4期28卷 683-691页

作者： Mborah Charles ge Maochen Department of Mining and Nuclear Engineering Missouri University of Science and Technology

Accurate detection and picking of the P-phase onset time in noisy microseismic data from underground mines remains a big challenge. Reliable P-phase onset time picking is necessary for accurate source location needed for planning and rescue operations in the event of failures. In this paper, a new technique based on the discrete stationary wavelet transform （DSWT）and higher order statist!cs, is proposed for processing noisy data from underground mines. The objectives of this method are to （1） Improve manual detection and tPicking of P-phase onset; and （ii） provide an automatic means of detecting and picking P-phase onset me accurately. The DSWT is first used to filter the signal over several scales. The manual P-phase onset detection and picking are then obtained by computing the signal energy across selected scales with frequency bands that capture the signal of interest. The automatic P-phase onset, on the other hand, is achieved by using skewness- and kurtosis-based criterion applied to selected scales in a time-frequency domain. The method was tested using synthetic and field data from an underground limestone mine. Results were compared with results obtained by using the short-term to long-term average （STA/LTA） ratio and that by Reference ge et al. （2009）. The results show that the me!hod provides a more reliable estimate of the P-phase onset arrival than the STA]LTA method when the signal to noise ratio is very low. Also, the results obtained from the field data matched accurately with the results from Reference ge et al. （2009）.

关键词： Manual P-phase detection Automatic onset picking Noisy microseismic data Kurtosis Skewness