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排序方式: 共有2876条查询结果,搜索用时 203 毫秒
1.
Abdul Rahman Mohtasebzadeh Longfei Ye Thomas M. Crawford 《International journal of molecular sciences》2015,16(8):19769-19779
We study magnetic-field directed self-assembly of magnetic nanoparticles onto templates recorded on perpendicular magnetic recording media, and quantify feature width and height as a function of assembly time. Feature widths are determined from Scanning Electron Microscope (SEM) images, while heights are obtained with Atomic Force Microscopy (AFM). For short assembly times, widths were ~150 nm, while heights were ~14 nm, a single nanoparticle on average with a 10:1 aspect ratio. For long assembly times, widths approach 550 nm, while the average height grows to 3 nanoparticles, ~35 nm; a 16:1 aspect ratio. We perform magnetometry on these self-assembled structures and observe the slope of the magnetic moment vs. field curve increases with time. This increase suggests magnetic nanoparticle interactions evolve from nanoparticle–nanoparticle interactions to cluster–cluster interactions as opposed to feature–feature interactions. We suggest the aspect ratio increase occurs because the magnetic field gradients are strongest near the transitions between recorded regions in perpendicular media. If these gradients can be optimized for assembly, strong potential exists for using perpendicular recording templates to assemble complex heterogeneous materials. 相似文献
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H.C. Weigele L. Gygax A. Steiner B. Wechsler J.-B. Burla 《Journal of dairy science》2018,101(3):2370-2382
Lameness is one of the most prevalent diseases affecting the welfare of cows in modern dairy production. Lameness leads to behavioral changes in severely lame cows, which have been investigated in much detail. For early detection of lameness, knowledge of the effects of moderate lameness on cow behavior is crucial. Therefore, the behavior of nonlame and moderately lame cows was compared on 17 Swiss dairy farms. On each farm, 5 to 11 nonlame (locomotion score 1 of 5) and 2 to 7 moderately lame (locomotion score 3 of 5) cows were selected for data collection in two 48-h periods (A, B) separated by an interval of 6 to 10 wk. Based on visual locomotion scoring, 142 nonlame and 66 moderately lame cows were examined in period A and 128 nonlame and 53 moderately lame cows in period B. Between these 2 periods, the cows underwent corrective hoof trimming. Lying behavior, locomotor activity, and neck activity were recorded by accelerometers (MSR145 data logger, MSR Electronics GmbH, Seuzach, Switzerland), and feeding and rumination behaviors by noseband sensors (RumiWatch halter, ITIN + HOCH GmbH, Liestal, Switzerland). Furthermore, visits to the brush and the concentrate feeder, and the milking order position were recorded. In comparison with nonlame cows, moderately lame cows had a longer lying duration, a longer average lying bout duration, and a greater lateral asymmetry in lying duration. Average locomotor activity, locomotor activity during 1 h after feed delivery or push-ups, and average neck activity were lower in moderately lame cows. Eating time and the number of eating chews (jaw movements) were reduced in moderately lame compared with nonlame cows, whereas no effect of moderate lameness was evident for ruminating time, number of ruminating chews and boluses, and average number of ruminating chews per bolus. Moderately lame cows visited the concentrate feeder and the brush less frequently, and they were further back in the milking order compared with nonlame cows. In conclusion, nonlame and moderately lame cows differed in a biologically relevant way in many of the behavioral variables investigated in this study. Therefore, the use of these behavioral changes seems to be promising to develop a tool for early lameness detection. 相似文献
3.
基于CVSD编码的无线语音系统方案的设计 总被引:2,自引:0,他引:2
简要介绍了连续可变斜率增量(CVSD)调制的原理。与目前应用较为广泛的其它语音编码方式相比较,CVSD拥有更优的数字特性。着重介绍了由CML公司研制开发的基于CVSD的语音编码芯片———CMX649的特点及相关的应用方式。CMX649能够成功地应用在广泛的语音编码系统中,尤其适合无线语音系统应用。在此基础上,给出了一种实用性很强的低成本、低功耗无线语音系统的设计与应用方案。该方案可提供清晰可靠的语音传输,可广泛应用于农村地区,具有广阔的市场空间。 相似文献
4.
结合NGN及3G演进的固定、移动视频业务实际需求状况,论述H.264/AVC的重要技术进展及其务实发展策略。 相似文献
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本文提出一种与现有以太网兼容的综合话音/数据协议.描述了协议模型及实现方法.并用PASCAL语言在IBM-PC机上模拟研究了该协议的性能.模拟结果表明,该协议能满足话音的实时要求,性能良好,且数据传输性能没有明显下降.协议克服了以太网传输话音延迟不确定的缺点. 相似文献
8.
Fe100-xPtx(x=30at.%-60at.% ) nanocomposite films were deposited on natural-oxidized Si(100) substrates by magnetron sputtering. The as-deposited films were annealed between 373 and 1073 K. In situ X-ray diffraction shows that the FePt nanocomposite films undergo a phase transformation from a disordered FCC phase to an ordered L10 phase between 673 and 773 K. The coercivity is 306 kA·m-1 whiles the average grain sizes is about 10 nm in the optimized FePt alloy film sample annealed at 673K. The adjustable coercivity and fine grain size suggest that this FePt nanocomposites system is suitable as recording media at extremely high areal density. 相似文献
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以ATM实现分组话音通信,需要解决两个基本问题:传输时延和分组丢失。针对这两个基本问题,本文着重讨论了ATM分组话音通信中32kb/sADPCM话音分组丢失的重建技术--于模式匹配的波形替代技术和静默重建技术,分别用以补偿由于网络阻塞造成的分组话音信息丢失而产生的失真和改善重建话音的自然性。 相似文献