In this paper, an application of wavelet packet-enhanced arithmetic coding to compress the electric power disturbance data is proposed. In the proposed method, the wavelet packet is first applied in anticipation that the disturbance signal can be optimally decomposed into higher frequency components and lower frequency ones on a best wavelet basis. Then, the arithmetic coding approach is utilized to reduce the redundancy of data encoding, thereby lowering down the cost related with data storage and transmission. This integrated method has been tested on different scenarios and the results are compared with other published techniques. 相似文献
In 3 experiments, participants identified target letters in multiletter strings of different interletter steps. Results show that the alphabetically extreme targets in the arrays (A or C in BCA) were consistently identified faster than were the interior letters, with the alphabetically middle target (B in BCA) identified most slowly. Distance effects were not consistent across different targets. The findings are not consistent with the ends-inward serial search, comparison, and serial search plus comparison models. The data suggest that an interior target was identified by first identifying the terminal letter and then mentally constructing the linear order inward by probabilistically using either a comparison or an interitem serial search process to achieve maximal efficacy. This suggestion is consistent with the ends-inward construction theory of linear-order learning. 相似文献
This paper proposes a new pipelined full-adder circuit structure for the implementation of pipelined arithmetic modules. With both static and dynamic structures, it has the advantages of high operational speed, smallest transistor count, and the low power/speed ratio. The adder cell is then used to design a pipelined 8×8-b multiplier-accumulator (MAC). In this MAC, a special pipelined structure is designed to reduce the latency. The MAC is fabricated in a 0.8-μm single-poly-double-metal CMOS process. The post-layout simulation shows that the pipelined 1-b full adder can work up to 350 MHz with a 3 V power supply. The whole MAC chip that contains 4200 transistors is measured to operate a 125 MHz using 3.3 V power supply 相似文献
The influence of conductive carbon-fiber orientation and weight percentage on the electromagnetic (EM) shielding effectiveness
(SE) in liquid-crystal polymer (LCP) composites was investigated experimentally and theoretically. The experimental results
show that the SE of LCP composites with longitudinal fiber orientation is higher than random fiber orientation under the same
weight percentage of carbon fibers filled. This is because longitudinal fiber orientation is parallel to the electric field
of the incident EM wave, and most of the energy of the incident wave is reflected by the longitudinal fiber. In comparison
with nylon66 composites, the SEs of LCP composites with longitudinal fiber orientation are also higher than nylon66 composites
with the same content of carbon fibers. Furthermore, the SE of 20% conductive carbon-fiber-filled LCP composites was measured
to be 50 dB at a frequency of 0.3 GHz and 53 dB at 1 GHz, which is at least 10 dB higher than that of nylon66 composites.
The SE predicted by theoretical models and measured by experiments was in good agreement for carbon-fiber-filled LCP composites
of longitudinal and random fiber orientations. 相似文献
A novel polyimide film, consisting of finely dispersed multiwall carbon nanotubes (MWCNTs) in an ionic liquid (IL), is demonstrated to be high shielding effectiveness (SE) for use in packaging a 2.5-Gbps plastic transceiver module. The IL-dispersed MWCNT composite exhibits a high SE of 40 ~ 46 dB. By comparison, the composite fabricated by nondispersive process requires a higher loading of MWCNTs at 50 wt- % than the IL-dispersed process at only 30 wt-%. The electromagnetic susceptibility (EMS) performance is experimentally evaluated by the eye diagram and bit-error-rate for a 2.5-Gbps lightwave transmission system. The package housing fabricated by the dispersive MWCNT composites shows an enhanced EMS performance, an improved mask margin, and a lower-power penalty. These results indicate that the IL-dispersed MWCNT composites are suitable for packaging low-cost and high-performance optical transceiver modules used in the fiber to the home lightwave transmission systems. 相似文献
We propose and demonstrate the use of fiber ring lasers and Fabry-Perot laser diodes (FP-LDs) for wavelength-division-multiplexing access networks. The fiber ring laser not only generates downstream data traffic but also serves as the wavelength-selecting injection light source for the FP-LD located at the subscriber site. Moreover, it is wavelength tunable and can be applied to dynamic wavelength assignment networks. The ring laser has a tunable range of 30 nm in the C-band and a power fluctuation smaller than 0.6 dB. For 10-Gb/s downstream and 1.25-Gb/s upstream transmissions over 10-km single-mode fiber, power penalties less than 0.9 and 0.5 dB are demonstrated, respectively. A 40-dB sidemode suppression ratio is obtained for the FP-LD injection-locking at 1544.8 nm. 相似文献
One of the key elements in improved management and better planning for aquifer maintenance is the ability to predict changes in aquifer depth. In order to forecast changes in aquifer depth in Qazvin plain, four methods, including Classification and Regression Tree (CART), Reduced Error Pruning Trees (RepTree), M5-Pruned (M5P), and M5Rule, were used in this work. The absolute mean error (MAE) and coefficient of determination (R2) data show that the CART algorithm performs better than other algorithms at forecasting changes in aquifer depth. The CART algorithm's prediction findings showed that the aquifer's behavior in the two seasons was entirely different. In the first stage, which began in November and continued through April, there was an annual average depth of 0.045 m. The aquifer depth has been greatly influenced by rising precipitation and falling air temperature. The aquifer experiences an average decline of 0.15 m in the second portion, which runs from May to October. Aquifer depth has significantly decreased as a result of declining natural water supplies and rising agricultural water use. It is advised to utilize a crop scheme with reduced water need when rainfall reduces due to the strong effect of changes in aquifer depth from rainfall with a delay of one to three months ago.
In this article, a new DC hybrid power filter is proposed to attenuate the low–frequency ripple of AC-DC power converter. The proposed DC hybrid power filter is connected between the DC bus of AC-DC power converter and the load, and it composes of a passive power filter and a single-arm power converter. The passive power filter can reduce the voltage rating of single-arm power converter, and the operation of single-arm power converter generates a virtual harmonic resistor connected to the load in series. The DC hybrid power filter can suppress the twice-utility-frequency ripple for eliminating the use of electrolytic capacitor. The salient feature is that the control circuit of the proposed DC hybrid power filter is simplified because only a feedforward control is used. A hardware prototype is developed to validate the performance of the proposed DC hybrid power filter. The experimental results are as expected. 相似文献