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241.
Dov Wulich 《International Journal of Circuit Theory and Applications》1993,21(1):35-40
The idea of discrete constrained notch filters is well known and widely described in the literature. Time-invariant as well as time-varying filters are considered. Because of the discrete nature of such filters, their application is limited to sampled signals, usually obtained as samples of low-frequency signals. the aim of this paper is to give some ideas on how to synthesize a time-varying analogue constrained notch filter which can be used directly for continuous signals. 相似文献
242.
Roasted macadamia (Macadamia integrifolia Storey) nuts were salted at various levels up to 19 g kg?1 and presented to a taste panel. The results showed that the assessors could be divided into 'salt dislikers', to whom perceived quality decreased linearly with increase in salt content, and 'salt likers', to whom perceived quality increased as the salt content increased. It follows that the nuts can be produced to suit these two market segments separately, or else a single lightly salted compromise product can be offered to both groups. 相似文献
243.
We review the status of European publishing in high-impact Information System (IS) journals finding that the European publication record is disappointing. We consider popular explanations to this state of affairs and find them neither credible nor useful for improving the European record. We propose several constructive reasons for this including (1) the lack of appreciation of the article genre, (2) weak publishing cultures, (3) inadequate Ph.D. preparation for article publishing, (4) weak reviewing practices, (5) poorer command of research methods, (6) poorer understanding of the reviewing protocols, and (7) institutional shaping of research funding in Europe. We formulate several recommendations to affect these causes at the individual, institutional, journal, and European community level. 相似文献
244.
Seawater has been irradiated using a train of 70 ns flashes from a 440 nm laser source. This wavelength is on resonance with the blue absorption peak of Chlorophyll pigment associated with the photosystem of in vitro phytoplankton. The resulting fluorescence at 685 nm is instantaneously recorded during each laser pulse using a streak camera. Delayed fluorescence is observed, yielding clues about initiation of the photosynthetic process on a nanosecond time scale. Further data processing allows for determination of the functional absorption cross section, found to be 0.0095 A(2), which is the first reporting of this number for in vitro phytoplankton. Unlike other flash-pump studies of Chlorophyll, using a LED or flashlamp-based sources, the short laser pulse used here does not reveal any pulse-to-pulse hysteresis (i.e., variable fluorescence), indicating that the laser pulses used here are not able to drive the photosynthetic process to completion. This is attributed to competition from a back reaction between the photoexcited photosystem II and the intermediate electron acceptor. The significance of this work as a new type of deployable ocean fluorimeter is discussed, and it is believed the apparatus will have applications in thin-layer phytoplankton research. 相似文献
245.
The ability to tailor the properties of semiconductor nanocrystals through creating core/shell heterostructures is the cornerstone for their diverse application in nanotechnology. The band-offsets between the heterostructure components are determining parameters for their optoelectronic properties, dictating for example the degree of charge-carrier separation and localization. So far, however, no method was reported for direct measurement of these factors in colloidal nanocrystals and only indirect information could be derived from optical measurements. Here we demonstrate that scanning tunneling spectroscopy along with theoretical modeling can be used to determine band-offsets in such nanostructures. Applying this approach to CdSe/CdS quantum-dot/nanorod core/shell nanocrystals portrays its type I band structure where both the hole and electron ground state are localized in the CdSe core, in contrast to previous reports which predicted electron delocalization. The generality of the approach is further demonstrated in ZnSe/CdS nanocrystals where their type II band alignment, leading to electron-hole separation, is manifested. 相似文献
246.
247.
Ehud Strobach David Faiman Shlomo Kabalo Dov Bokobza Vladimir Melnichak Andreas Gombert Tobias Gerstmaier Michael Rttger 《Progress in Photovoltaics: Research and Applications》2015,23(5):582-592
A six‐parameter formula is proposed for describing the hourly alternating current performance of a grid‐connected, passively cooled concentrator photovoltaic (CPV) system. These system parameters all have physical meanings, and techniques are described for deriving their numerical values. The predictions of the model are compared with the measured output of a Soitec CPV system at Sede Boqer and found to be accurate to approximately ± 5% at all times of the year. The model should also be valid for systems of similar construction operated in different climates from the system studied here, and also for passively cooled CPV systems of different designs provided that suitable numerical values are determined for their system parameters. Another possible use of the model is as a guide for tailoring CPV cell architecture to the particular spectral conditions of the locations in which they will operate. Attention is drawn to the fact that the numerical values of some of the system parameters are found to depend upon the time binning employed for the data. An explanation is given for this phenomenon, which is also found to occur for non‐concentrating photovoltaic panels. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
248.
Shay Hamer Herman Leibovich Anthony Green Ron Intrater Ron Avrahami Eyal Zussman Arnon Siegmann Dov Sherman 《Polymer Composites》2011,32(11):1781-1789
Carbon/epoxy laminates interleaved with laboratory scale electrospun Nylon 66 nanofibrilmat and spunbonded nonwoven mats were investigated. The effect of the nanoscale fibers on the fracture toughness of the composite under pure Mode I loading was evaluated. It was shown that the nanofibrilmat is responsible for a major interlaminar fracture toughness improvement, as high as 255–322%, compared to a noninterleaved carbon/epoxy reference laminate. We further studied the improvement mechanism of the electrospun nanofibrilmat compared to a commercial spunbonded nonwoven Nylon 66 mat. A combination of two interlayer fracture mechanisms responsible for the toughness improvement is suggested: the first is related to the high energy dissipated by bridged thermoplastic nanofibers and the second is attributed to the generation of a plastic zone near the crack tip. The interlaminar fracture mechanisms of both electrospun nanofibrilmat and the nonwoven mat interleaving was analyzed and discussed. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers 相似文献