检索结果-南通市图书馆

Identification of abnormal tribological regimes using a microphone and semi-supervised machine-learning algorithm

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Friction 2022年第4期10卷 583-596页

作者： Vigneashwara PANDIYAN Josef PROST georg vorlaufer Markus VARGA Kilian WASMER Laboratory for Advanced Materials Processing(LAMP) Swiss Federal Laboratories for Materials Science and Technology(Empa)Thun CH-3602Switzerland AC2T research GmbH Viktor-Kaplan-Straße 2/CWiener Neustadt 2700Austria

Functional surfaces in relative contact and motion are prone to wear and tear,resulting in loss of efficiency and performance of the workpieces/*** occurs in the form of adhesion,abrasion,scuffing,galling,and scoring between ***,the rate of the wear phenomenon depends primarily on the physical properties and the surrounding *** the integrity of surfaces by offline inspections leads to significant wasted machine time.A potential alternate option to offline inspection currently practiced in industries is the analysis of sensors signatures capable of capturing the wear state and correlating it with the wear phenomenon,followed by in situ classification using a state-of-the-art machine learning(ML)*** this technique is better than offline inspection,it possesses inherent disadvantages for training the ML ***,supervised training of ML models requires the datasets considered for the classification to be of equal weightage to avoid *** collection of such a dataset is very cumbersome and expensive in practice,as in real industrial applications,the malfunction period is minimal compared to normal ***,classification models would not classify new wear phenomena from the normal regime if they are *** a promising alternative,in this work,we propose a methodology able to differentiate the abnormal regimes,i.e.,wear phenomenon regimes,from the normal *** is carried out by familiarizing the ML algorithms only with the distribution of the acoustic emission(AE)signals captured using a microphone related to the normal *** a result,the ML algorithms would be able to detect whether some overlaps exist with the learnt distributions when a new,unseen signal *** achieve this goal,a generative convolutional neural network(CNN)architecture based on variational auto encoder(VAE)is built and *** the validation procedure of the proposed CNN architectures,we were

关键词： surface integrity acoustic emission auto encoders condition monitoring wear prediction

Longs short-term based semi-supervised memory encoder-decoder for early prediction of failures in self-lubricating bearings

在线全文

学校读者我要写书评

暂无评论

Friction 2023年第1期11卷 109-124页

作者： Vigneashwara PANDIYAN Mehdi AKEDDAR Josef PROST georg vorlaufer Markus VARGA Kilian WASMER Laboratory for Advanced Materials Processing(LAMP) Swiss Federal Laboratories for Materials Science and Technology(Empa)Thun CH-3602Switzerland AC2T research GmbH Wiener Neustadt 2700Austria

The existing knowledge regarding the interfacial forces,lubrication,and wear of bearings in real-world operation has significantly improved their designs over time,allowing for prolonged service *** a result,self-lubricating bearings have become a viable alternative to traditional bearing designs in industrial ***,wear mechanisms are still inevitable and occur progressively in self-lubricating bearings,as characterized by the loss of the lubrication film and ***,monitoring the stages of the wear states in these components will help to impart the necessary countermeasures to reduce the machine maintenance *** article proposes a methodology for using a long short-term memory(LSTM)-based encoder-decoder architecture on interfacial force signatures to detect abnormal regimes,aiming to provide early predictions of failure in self-lubricating sliding contacts even before they *** sliding experiments were performed using a self-lubricating bronze bushing and steel shaft journal in a custom-built transversally oscillating tribometer *** force signatures corresponding to each cycle of the reciprocating sliding motion in the normal regime were used as inputs to train the encoder-decoder architecture,so as to reconstruct any new signal of the normal regime with the minimum *** this semi-supervised training exercise,the force signatures corresponding to the abnormal regime could be differentiated from the normal regime,as their reconstruction errors would be very *** the validation procedure for the proposed LSTM-based encoder-decoder model,the model predicted the force signals corresponding to the normal and abnormal regimes with an accuracy of 97%.In addition,a visualization of the reconstruction error across the entire force signature showed noticeable patterns in the reconstruction error when temporally decoded before the actual critical failure point,making it possible to be used for early predic

关键词： predictive maintenance in-situ sensing long short-term memory(LSTM) encoder-decoder wear monitoring tribology

CO_2 mitigation potential in farmland of China by altering current organic matter amendment pattern

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 2010年第9期53卷 1351-1357,1407-1417页

作者： CADISCH georg Institute of Plant Production and Agroecology in the Tropics and Subtropics University of Hohenheim

The estimation of the global warming mitigation potential in terrestrial ecosystems is of great importance for decision makers to adopt measures to increase soil organic carbon (SOC) as well as to reduce greenhouse gas (GHGs) emissions. In this paper, we compiled data published in peer-reviewed journals, and conducted a holistic analysis of the effects of organic matter amendment on soil organic carbon sequestration, methane (CH4) and nitrous oxide (N2O) emissions in paddy and upland systems. Results showed that organic matter amendment increased soil organic carbon content, and apparent conversion rate of organic matter carbon to soil organic carbon in paddies was constant, while that in uplands decreased along with amendment years at 25 years time scale. Organic matter amendment during the rice season led to large CH4-C emissions, e.g on average 99.5 g CH4-C per kg organic carbon input under intermittent flood conditions, and 191.7 g CH4-C per kg organic carbon input under continuous flood conditions, respectively. By alteration of organic matter amendment from rice season to off-rice upland crop season, estimated CH4-C emissions in China could be cut by 3.5 Tg yr-1, accounting for 63% of current CH4-C emissions (5.5 Tg). If organic matter amendment percentage was increased from current 30% to future 50% of organic matter production and by alteration of organic matter amendment from rice season to off-rice upland crop season, the equivalent CO2-C mitigation potential in farmland of China would be 49.2 Tg yr-1 at the 10th year organic matter amendment and 36.0 Tg yr-1 at the 30th year amendment. These findings are important not only for China but also for the other rice production countries to increase farmland global warming mitigation.

关键词： climate change global warming radiative forcing SOC GHGs CH4 N2O

Yield Improvement and Advanced Defect Control——Driving Forces for Modeling of Bulk Crystal Growth

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2006年第z1期24卷 200-207页

作者： georg Mueller Jochen Friedrich Crystal Growth Laboratory University Erlangen-Nürnberg (WW6) and Fraunhofer Institute of Integrated Systems and Device Technology (IISB) Martensstrasse 7 D-91058 Erlangen Germany Crystal Growth Laboratory University Erlangen-Nürnberg (WW6) and Fraunhofer Institute of Integrated Systems and Device Technology (IISB) Martensstrasse 7 D-91058 Erlangen Germany

Yield improvement and advanced defect control can be identified as the driving forces for modeling of industrial bulk crystal growth. Yield improvement is mainly achieved by upscaling of the whole crystal growth apparatus and increased processing windows with more tolerances for parameter variations. Advanced defect control means on one hand a reduction of the number of deficient crystal defects and on the other hand the formation of beneficial crystal defects with a uniform distribution and well defined concentrations in the whole crystal. This "defect engineering" relates to the whole crystal growth process as well as the following cooling and optional annealing processes, respectively. These topics were illustrated in the paper by examples of modeling and experimental results of bulk growth of silicon (Si), gallium arsenide (GaAs), indium phosphide (InP) and calcium fluoride (CaF2). These examples also involve the state of the art of modeling of the most important melt growth techniques, crystal pulling (Czochralski methods) and vertical gradient freeze (Bridgman-type methods).

关键词： yield improvement advanced defect control crystal growth

RESILIENCE 2.0： COMPUTER-AIDED DISASTER MANAGEMENT

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Science and Systems Engineering 2017年第3期26卷 321-335页

作者： Gerhard Chroust georg Aumayr Institute for Telecooperation Johannes Kepler University Linz Austria Johanniter Osterreich Ausbildung und Forschung Vienna Austria

Many factors （larger population, more dependency on technology, more human-caused interference in the natural systems and equilibria, climate changes,... ） contribute to the seemingly growing number and severity of disasters. Additional exaggeration is generated by public media. As a consequence Disaster Prevention and Disaster Management must be given increased attention. The ultimate goal of Disaster Management is resilience of the affected system and thus the adequate and acceptable survival of the affected population. We discuss system behavior in the case of an assault or disturbance： from being fragile （loss of their functionality due to the assault） to being resilient （having the capacity ... of bouncing back to dynamic stability after a disturbance）, or even antifragile （being able to ＂learn＂ so as to improve disaster resilience）. Resilience 2. 0 identifies a new paradigm： modem Information and Communication Technologies （ICT） are employed as a basis for enabling and improving resilience of a system. ICT provide the basis for sufficient preparation before an assault, for quick recognition of, and for effective, efficient reactions to disasters. Only the coordinated intra- and interphase deployment of ICT promises sufficient success and can bring resilience to currently as yet fragile systems. We discuss stressors （time and performance pressure, physical and psychological stress on personnel） and problems due to damaged ICT-platforms and communication infrastructure. The basic message is that computer-aided Disaster Management is able to offers a new level of reactivity： Resilience 2.0.

关键词： Disaster vulnerability resilience human reaction hazard threat systemic reaction

On the Connection Between the Spectral Difference Method and the Discontinuous Galerkin Method

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Computational Physics 2011年第4期9卷 1071-1080页

作者： georg May Aachen Institute for Advanced Study in Computational Engineering Sciences RWTH Aachen UniversitySchinkelstr.252062 AachenGermany

In this short note we present a derivation of the Spectral Difference Scheme from a Discontinuous Galerkin(DG)discretization of a nonlinear conservation *** allows interpretation of the Spectral Difference Scheme as a particular discretization under the quadrature-free nodal DG ***,it enables identification of the key differences between the Spectral Difference Scheme and standard nodal DG schemes.

关键词： Spectral difference method discontinuous Galerkin method hyperbolic conservation laws quadrature-free schemes nodal schemes

Introducing robustness in model predictive control with multiple models and switching

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Control Theory and Technology 2014年第3期12卷 284-303页

作者： Sachin PRABHU Koshy georg Department of Telecommunication Engineering PES Institute of Technology Bangalore 560085 India PES Centre for Intelligent Systems Bangalore 560085 IndiaE

Model predictive control is model-based. Therefore, the procedure is inherently not robust to modelling uncertainties. Further, a crucial design parameter is the prediction horizon. Only offline procedures to estimate an upper bound of the optimal value of this parameter are available. These procedures are computationally intensive and model-based. Besides, a single choice of this horizon is perhaps not the best option at all time instants. This is especially true when the control objective is to track desired trajectories. In this paper, we resolve the issue by a time-varying horizon achieved by switching between multiple model-predictive controllers. The stability of the overall system is discussed. In addition, an introduction of multiple models to handle modelling uncertainties makes the overall system robust. The improvement in performance is demonstrated through several examples.

关键词： Receding horizon control Time-varying horizon Multiple models Switching Tracking Robustness

The quest for conditional independence in prospectivity modeling： weights-of-evidence, boost weights-of-evidence, and logistic regression

在线全文

学校读者我要写书评

暂无评论

Frontiers of Earth Science 2016年第3期10卷 389-408页

作者： Helmut SCHAEBEN georg SEMMLER Department of Geophysics and Geoinformatics TU Bergakademie Freiberg Freiberg 09596 Germany

The objective of prospectivity modeling is prediction of the conditional probability of the presence T = 1 or absence T = 0 of a target T given favorable or prohibitive predictors B, or construction of a two classes {0,1} classification of T. A special case of logistic regression called weights-of-evidence （WofE） is geolo- gists＇ favorite method of prospectivity modeling due to its apparent simplicity. However, the numerical simplicity is deceiving as it is implied by the severe mathematical modeling assumption of joint conditional independence of all predictors given the target. General weights of evidence are explicitly introduced which are as simple to estimate as conventional weights, i.e., by counting, but do not require conditional independence. Complementary to the regres- sion view is the classification view on prospectivity modeling. Boosting is the construction of a strong classifier from a set of weak classifiers. From the regression point of view it is closely related to logistic regression. Boost weights-of-evidence （BoostWofE） was introduced into prospectivity modeling to counterbalance violations of the assumption of conditional independence even though relaxation of modeling assumptions with respect to weak classifiers was not the （initial） purpose of boosting. In the original publication of BoostWofE a fabricated dataset was used to ＂validate＂ this approach. Using the same fabricated dataset it is shown that BoostWofE cannot generally compensate lacking condi- tional independence whatever the consecutively proces- sing order of predictors. Thus the alleged features of BoostWofE are disproved by way of counterexamples, while theoretical findings are confirmed that logistic regression including interaction terms can exactly com- pensate violations of joint conditional independence if the predictors are indicators.

关键词： general weights of evidence joint conditionalindependence naive Bayes model Hammersley-Cliffordtheorem interaction terms statistical significance

Ethylene Controls Autophosphorylation of the Histidine Kinase Domain in Ethylene Receptor ETR1

在线全文

学校读者我要写书评

暂无评论

Molecular Plant 2008年第2期1卷 380-387页

作者： Jan Voet-van-Vormizeele georg Groth Heinrich-Heine-Universitat Biochemie der Pflanzen Universitatsstr. 1 40225 Duisseldorf Germany

Perception of the phytohormone ethylene is accomplished by a small family of integral membrane receptors. In Arabidopsis, five ethylene receptor proteins are known, including ethylene resistant I （ETR1）. The hydrophobic aminoterminal domain of these receptors contains the ethylene-binding site while the carboxyl-terminal part consists of a histidine kinase domain and a response regulator domain, which are well known elements found in bacterial two-component signaling. The soluble membrane-extrinsic carboxyl-terminal part of the receptor, which is likely to play an important role in signal transduction, showed intrinsic kinase activity when expressed and purified on its own. However, a correlation between signal input and autokinase activity was not established in these studies, as receptors were missing the trans- membrane amino-terminal sensor domain. Thus, it is still unclear whether autophosphorylation occurs in response to perception of the ethylene signal. Here, we report on autophosphorylation studies of purified full-length ETR1. Autoki- nase activity of the purified receptor is controlled by ethylene or by ethylene agonists like the π-acceptor compound cyanide. In fact, both signal molecules were able to completely turn off the intrinsic kinase activity, Furthermore, the observed inhibition of autophosphorylation in ETR1 by both molecules could be prevented when the ethylene antagonist 1-methyl-cyclopropene （MOP） was applied.

关键词： ethylene pathway phytohormone receptor membrane protein two-component system signaltransduction Arabidopsis thaliana,