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Memory Properties (memory + property)
Selected AbstractsTrends in timing of low stream flows in Canada: impact of autocorrelation and long-term persistenceHYDROLOGICAL PROCESSES, Issue 8 2010Eghbal Ehsanzadeh Abstract The annual timing of river flows might indicate changes that are climate related. In this study, trends in timing of low flows for the Reference Hydrometric Basin Network were investigated under three different hypotheses namely: independence, short-term persistence (STP) and long-term persistence (LTP). Both summer and winter time series were characterized with scaling behaviour providing strong evidence of LTP. The Mann,Kendall trend test was modified to account for STP and LTP, and used to detect trends in timing of low flows. It was found that considering STP and LTP resulted in a significant decrease in the number of detected trends. Numerical analysis showed that the timing of summer 7-day low flows exhibited significant trends in 16, 9 and 7% of stations under independence, STP and LTP assumptions, respectively. Timing of summer low flow shifted toward later dates in western Canada, whereas the majority of stations in the east half of the country (except Atlantic Provinces) experienced a shift toward earlier dates. Timing of winter low flow experienced significant trends in 20, 12, and 6% of stations under independence, STP and LTP assumptions, respectively. Shift in timing of winter low flow toward earlier dates was dominant all over the country where it shifted toward earlier dates in up to 3/4 of time series with significant trends. There are local patterns of upward significant/insignificant trends in southeast, southwest and northern Canada. This study shows that timing of low flows in Canada is time dependent; however, addressing the full complexity of memory properties (i.e. short term vs long term) of a natural process is beyond the scope of this study. Copyright © 2009 John Wiley & Sons, Ltd. [source] Low-Temperature Solution-Processed Memory Transistors Based on Zinc Oxide NanoparticlesADVANCED MATERIALS, Issue 30 2009Hendrik Faber We report on thin!film transistors based on ZnO nanoparticles processed from solution and with a maximum temperature of 100,°C. Electron mobilities up to 2.5,cm2V,1s,1 are obtained, and top-gate TFTs show non-volatile memory properties with a large, stable hysteresis and a memory ratio of 105. Memory TFTs operate in ambient, have good shelf-life (>6 months), and useful endurance properties. [source] Space-time ring-TCM codes with CPM based on the decomposed model for transmission over Rayleigh fading channelsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 5 2006A. Pereira Abstract Space,time (ST) coding is a proved technique for achieving high data rates in 3G mobile systems that combines coding, modulation and multiple transmitters and receivers. A novel algorithm is proposed for ST ring trellis-coded modulation (ST-RTCM) systems with continuous-phase modulation (CPM) when the channel coefficients are known to the receiver. This algorithm is based on the CPM decomposed model, which exploits the memory properties of this modulation method, resulting in a straightforward implementation of joint ST coding and CPM, which is particularly suitable for ring codes. This new scheme is used to investigate the performance of the delay diversity code with CPM over slow Rayleigh fading channels, in particular with MSK which is one of the most widely used modulation methods of continuous phase. Furthermore, a feedback version of delay diversity allowed by the decomposition is tested in 1REC and 1RC systems. This feedback configuration is seen to provide good results for low signal-to-noise ratios. Simulations results are also provided for multilevel ST-RTCM codes that achieve a higher throughput than MSK-coded systems. Additionally the serial concatenation of an outer Reed,Solomon code with an ST-RTCM code is shown, this combination further reduces the error probability and achieves even more reliable communications. Copyright © 2005 John Wiley & Sons, Ltd. [source] Effect of glucose crosslinking on thermomechanical properties and shape memory effect of PET-PEG copolymersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Yong-Chan Chung Abstract Poly(ethylene terephthalate) (PET) and poly (ethylene glycol) (PEG) copolymers crosslinked with glucose as a crosslinker are prepared to improve their mechanical and shape memory properties compared to the one without crosslinking. Composition of PEG and glucose is varied to search for the one with the best mechanical and shape memory properties. The highest shape recovery rate is found in the copolymer composed of 25 mol % PEG-200 and 2.0 mol % glucose. The result that crosslinking by glucose improves the shape recovery rate and supports the high shape recovery rate under the repetitive cyclic test conditions, compared to the one without crosslinking, will be discussed in the points of the structure and shape memory mechanism. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Estimating the long memory granger causality effect with a spectrum estimatorJOURNAL OF FORECASTING, Issue 3 2006Wen-Den ChenArticle first published online: 11 APR 200 Abstract This paper discusses the Granger causality test by a spectrum estimator which allows the transfer function to have long memory properties. In traditional methodology the relationship among variables is usually assumed to be short memory or contemporaneous. Hence, we have to make sure they are of the same integrated order, else there might be a spurious regression problem. In practice, not all the variables are fractionally co-integrated in the economic model. They may have the same random resources, but under a different integrated order. This paper focuses on how to capture the long memory Granger causality effect in the transfer function. This does not necessarily assume the variables are of the same fractional integrated order. Moreover, by the transfer function we construct an estimator to test the long memory effect with the Granger causality sense. Copyright © 2006 John Wiley & Sons, Ltd. [source] Novel Shape-Memory Materials Based on Potato StarchMACROMOLECULAR MATERIALS & ENGINEERING, Issue 2 2010Cyril Véchambre Abstract Shape-memory properties such as shape fixity and recovery ratio of amorphous starch-based materials extruded under normal conditions were evaluated for the case of single and cyclic recovery processing. This study focused on the effect of moisture as a stimulus for the activation of recovery. A high recovery ratio (Rr,>,90%) was obtained at high relative humidity, at deformation ratios up to 200%. In the case of plasticized starch with a glycerol content of 10%, the recovery ratio was close to 50% because crystallization limited the shape recovery. Results were compared to those obtained with synthetic or bio-based shape-memory polymers such as semi-crystalline PU or PLAGC. Efficient shape memory properties for a non-modified biopolymer are highlighted in this study. [source] Minimum capital requirement calculations for UK futuresTHE JOURNAL OF FUTURES MARKETS, Issue 2 2004John Cotter Key to the imposition of appropriate minimum capital requirements on a daily basis is accurate volatility estimation. Here, measures are presented based on discrete estimation of aggregated high-frequency UK futures realizations underpinned by a continuous time framework. Squared and absolute returns are incorporated into the measurement process so as to rely on the quadratic variation of a diffusion process and be robust in the presence of fat tails. The realized volatility estimates incorporate the long memory property. The dynamics of the volatility variable are adequately captured. Resulting rescaled returns are applied to minimum capital requirement calculations. © 2004 Wiley Periodicals, Inc. Jrl Fut Mark 24:193,220, 2004 [source] | ||||||||||||||||