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排序方式: 共有270条查询结果,搜索用时 46 毫秒
21.
Edoardo Guerrini Pierangela Cristiani Stefano Pierpaolo Marcello Trasatti 《International Journal of Hydrogen Energy》2013
One-compartment (membraneless) microbial fuel cells (MFCs) are effective tools to test new bio-technology at a laboratory level. More efforts in MFC design and materials are necessary to move from laboratory tests to real applications. 相似文献
22.
The paper addresses two of the basic issues of switching supervisory control (SSC): controller falsification (CF) and inference of candidate loop behaviour (ICLB). CF is approached as a statistical fault detection problem in that the currently operating controller is falsified as soon as a divergence trend is detected. This is achieved by considering a statistic (or residual) in the form of a ratio of closed-loop variables, and the falsification test is carried out by comparing at each time the ratio statistic with a threshold. It is constructively shown that the thresholds can be fixed, irrespective of the disturbance intensity, in such a way that faults are detected with probability one while probability of false alarms can be made as small as we wish. The ICLB issue is approached by the virtual reference approach. This allows one to obtain an inference of the performance of a candidate loop via a mean-square average of suitably filtered prediction errors. It is shown how a supervisory logic can be built by combining the results on CF with those on ICLB. 相似文献
23.
Nicola Segata Edoardo Pasolli Enrico Blanzieri 《International journal of remote sensing》2013,34(19):6186-6201
In this article, the task of remote-sensing image classification is tackled with local maximal margin approaches. First, we introduce a set of local kernel-based classifiers that alleviate the computational limitations of local support vector machines (SVMs), maintaining at the same time high classification accuracies. Such methods rely on the following idea: (a) during training, build a set of local models covering the considered data and (b) during prediction, choose the most appropriate local model for each sample to evaluate. Additionally, we present a family of operators on kernels aiming to integrate the local information into existing (input) kernels in order to obtain a quasi-local (QL) kernel. To compare the performances achieved by the different local approaches, an experimental analysis was conducted on three distinct remote-sensing data sets. The obtained results show that interesting performances can be achieved in terms of both classification accuracy and computational cost. 相似文献
24.
Edoardo Magnone 《Scientometrics》2014,101(1):179-201
How has the terrorism affected the research process and findings? The author tries to answer to this question through an exploratory analysis of the impact of these tragic events on the research outputs of scientists, institutions and countries. In particular, this report provides a wide range of scientometric data related to terrorism studies over the world during the two decades from 1991 to 2011. After the September 11, 2001 events (9/11) in the United States, the concerned academicians have responded in a way that they started producing an increasing number of research publications, as if they were under the influence of some kind of a driving force, stimulating the overall academic production linked to this tragic event. However, after this trend has reached its peak in 2002, that driving force has visibly weakened, and since the mid 2000’s, the number of research publication in the field of terrorism studies has steadily decreased. Nonetheless, the number of terrorist events per year, along with the property damage and fatality rate, has continuously increased over the observed lapse of time. Using these results as a backdrop, in this paper is argued that the field of terrorism research should be explored from a critical and multi-cultural perspective, and that all scientific researchers should remain objective, for scientific research is to be independent from political systems, its contingent events in any form, and the transitory historical circumstances. 相似文献
25.
E. Scarpetta 《Acta Mechanica》2002,154(1-4):179-187
Summary In the context of wave propagation in damaged (elastic) solids, an analytical method previously introduced for scalar problems, is now applied to study the (vector) problem for normal penetration of a longitudinal plane wave into a periodic array of collinear cracks. Reduced the problem to an integral equation holding over the openings, an approximation of one-mode type leads to analytical solutions and then to explicit representations for the wave fields and the scattering parameters. Some graphs will finally compare our results with the numerical ones by other authors. 相似文献
26.
Control of beam vibrations by means of piezoelectric devices: theory and experiments 总被引:1,自引:0,他引:1
The problem of the attenuation of the vibration effects in active cantilever beams has been approached by two strategies, position and velocity control, which have been simulated numerically and analysed experimentally. The numerical simulation has been developed by means of a finite element approach based on an Euler–Bernoulli model and subsequent modal factorisation. Each device as well as each electronic circuit, present in the single-input single-output control system has been modelled and the results of the numerical simulations have been compared with the ones obtained in the experimental tests. A good correspondence has been obtained in all the examined cases. 相似文献
27.
This paper proves the validity of a basic feasibility property which makes it possible to extend, to the case of set-point tracking in ANCBI systems under joint positional and incremental input saturations, the approach in [Mosca, E. (2005). Predictive switching supervisory control of persistently disturbed input-saturated plants. Automatica, 41, 55-67] restricted to positional input saturation and the pure regulation problem. An example on the use of the proposed technique is considered. 相似文献
28.
Edoardo Mosca Author Vitae 《Automatica》2005,41(1):55-67
Predictive switching logic schemes are considered whereby a feedback-gain is switched-on at any time from a family of candidate feedback-gains so as to control a discrete-time input-saturated LTI system possibly subject to persistent bounded disturbances of unknown arbitrary magnitude. It is constructively shown that such schemes do exist which ensure, along with good tracking performance, global asymptotic and semi-global exponential stability in the noiseless case, as well as finite l∞-induced gain to the disturbance-to-state map, whenever the structure of the disturbed plant can make such properties conceptually achievable, viz., the disturbance which enters an Asymptotically Null-Controllable with Bounded Input (ANCBI) system acts directly only on the stable modes, while the critically unstable ones are indirectly affected by the disturbance only via the feedback controls. More generally, in ANCBI systems general disturbances of suitably bounded magnitude can also be handled by the scheme, provided that the switching logic be equipped with an appropriate hysteresis facility. 相似文献
29.
Arturo Di Fraia Edoardo Miliotti Andrea Maria Rizzo Giulia Zoppi Giuseppe Pipitone Raffaele Pirone Luca Rosi David Chiaramonti Samir Bensaid 《American Institute of Chemical Engineers》2023,69(1):e17652
Lignin-rich stream from lignocellulosic ethanol production was converted into biocrude by continuous hydrothermal liquefaction (HTL) while hydrogen was produced by aqueous phase reforming (APR) of the HTL aqueous by-product. The effects of Na2CO3 and NaOH were investigated both in terms of processability of the feedstock as well as yield and composition of the obtained products. A maximum biocrude yield of 27 wt% was reached in the NaOH-catalyzed runs. A relevant amount of dissolved phenolics were detected in the co-produced aqueous phase (AP), and removed by liquid–liquid extraction using butyl acetate or diethyl ether, preserving the APR catalyst stability and reaching an hydrogen yield up to 146 mmol H2 L−1 AP. Preliminary mass balances integrating HTL and APR showed that the hydrogen provided by APR may account for up to 46% of the hydrogen amount theoretically required for upgrading the HTL biocrude, thus significantly improving the process performance and sustainability. 相似文献
30.
Measures to evaluate the diversity of a set of points (population) in Euclidean space play an important role in a variety of areas of science and engineering. Well-known measures are often used without a clear insight into their quality and many of them do not appropriately penalize populations with a few distant groups of collocated or closely located points. To the best of our knowledge, there is a lack of rigorous criteria to compare diversity measures and help select an appropriate one. In this work we define a mathematical notion of ectropy for classifying diversity measures in terms of the extent to which they tend to penalize point collocation, we investigate the advantages and disadvantages of several known measures and we propose some novel ones that exhibit a good ectropic behavior. In particular, we introduce a quasi-entropy measure based on a geometric covering problem, three measures based on discrepancy from uniform distribution and one based on Euclidean minimum spanning trees. All considered measures are tested and compared on a large set of random and structured populations. Special attention is also devoted to the complexity of computing the measures. Most of the novel measures compare favorably with the classical ones in terms of ectropy. The measure based on Euclidean minimum spanning trees turns out to be the most promising one in terms of the tradeoff between the ectropic behavior and the computational complexity. 相似文献