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In this paper, we propose a new peak-to-average power ratio (PAPR) reduction algorithm for OFDM transmission. The algorithm is based on simple amplitude predistortion of a subset of the input symbol blocks, the predistorted symbols being selected according to a metric which measures their contribution to the output signal samples of large. magnitude. This metric-based algorithm is simple, highly flexible, and can be implemented as a one-shot process, although its performance can be further improved by iterating the process one or more times.  相似文献   
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本文报导用于异丁烯(叔丁醇)选择氧化制MAL(甲基丙烯醛)的多元复合氧化物催化剂的研究结果。同共沉淀法制备的催化剂的活性主要决定于其化学组成,同时受到制备条件的影响。最佳催化剂的主要物相组成为PbO3,Bi2MoO3.3、NiMoO4、Sb2O3及a-Fe2O3小颗粒。在355℃,1000~2500h-1空速范围,叔丁醇:水:空气=1:3.3:7(摩尔比)的条件下可获得异丁烯转化率达96%,MAL选择性达89%的结果。  相似文献   
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Water hydraulic systems use water as a pressure medium and, thus, do not pose such adverse environmental impacts as oil hydraulics. Microbial deterioration of the pressure medium and biofouling of the surfaces restrict the applicability of the water‐based technology. The potential of microbial growth control by UV‐irradiation and filtration was studied in a pilot‐scale water hydraulic system. The UV‐irradiation (25 m Ws cm?2) of the pressure medium reduced the total viable counts of bacteria by 1–2 log10 cfu cm?3, whereas the total microbial cell numbers and the numbers of surface‐attached microorganisms remained unaffected. Prefiltration (1.2 µm, absolute) of the pressure medium decreased the total microbial cell number in the water phase and retarded the attachment of bacteria. The filtration during the operation (2 µm, absolute) decreased the total numbers of microbial cells and the total viable counts in the pressure medium, and microbial attachment on the surfaces. Microbial attachment was not prevented by filtration. The microbial water quality obtained by pre‐ and on‐line filtration of the pressure medium was sufficient to ensure the long‐term operation of the water hydraulic system assuming that clean work practices are complied with in assembly and during the operation. © 2002 Society of Chemical Industry  相似文献   
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Drying, water fractions, and water distribution were investigated for pine, birch, and reed pulps and pine–birch, pine–reed, and pine–birch–reed pulp mixtures. Gravimetrically determined drying times showed that the drying rates of the pulps decreased at two to four inflection points. Characterizations of the dried pulps by differential scanning calorimetry (DSC) showed a faster removal of free water than freezing and nonfreezing bound waters; all decreased simultaneously, however. DSC also revealed the critical water contents at which the free water and freezing bound water disappeared. The gravimetrically determined inflection points of the drying curves corresponded with the critical points determined by DSC. NMR line widths and images produced by 1H‐NMR imaging revealed the nature and regions of the pulp drying. The constant growth rate of the NMR line widths with decreasing water content appeared to change at two inflection points, which fell approximately in the same water content regions as the inflection points of the drying curves. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 937–945, 2006  相似文献   
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车载悬架性能检测与可调阻尼减震器   总被引:2,自引:0,他引:2  
刘文强  王磊  谢伟东 《机床与液压》2003,(3):278-279,296
本文采用模糊控制理论,论述了基于被动悬架性能测试基础上的阻尼调节技术,建立了1/4车被动悬架的检测判别理论模型,进行了模拟计算分析,仿真表明,能够提高车辆的安全性,同时,为设计制造性能可靠高效的可调阻尼悬架系统打下良好基础。  相似文献   
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This paper presents a new approach to make current and future television universally accessible. The proposed approach provides a means of universal accessibility both for remotely operating the TV set and for interacting with online services delivered through the TV. This proposal is based on the ISO/IEC 24752 “Universal Remote Console” (URC) standard. This standard defines an abstract user interface layer called the “user interface socket” and allows the development of pluggable (plug-in) user interfaces for any type of user and any control device. The proposed approach lays the foundation for the development of advanced user interfaces that can be interacted within various modalities. Different prototypes have been developed based on this approach and tested with end users. The user tests have shown this approach to be a viable option for the proposed scenarios. Based on the experience gathered with the prototypes, recommendations and implementation options are suggested for commercial adoption.  相似文献   
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Materials with controllable multifunctional abilities for optical imaging (OI) and magnetic resonant imaging (MRI) that also can be used in photodynamic therapy are very interesting for future applications. Mesoporous TiO2 sub‐micrometer particles are doped with gadolinium to improve photoluminescence functionality and spin relaxation for MRI, with the added benefit of enhanced generation of reactive oxygen species (ROS). The Gd‐doped TiO2 exhibits red emission at 637 nm that is beneficial for OI and significantly improves MRI relaxation times, with a beneficial decrease in spin–lattice and spin–spin relaxation times. Density functional theory calculations show that Gd3+ ions introduce impurity energy levels inside the bandgap of anatase TiO2, and also create dipoles that are beneficial for charge separation and decreased electron–hole recombination in the doped lattice. The Gd‐doped TiO2 nanobeads (NBs) show enhanced ability for ROS monitored via ?OH radical photogeneration, in comparison with undoped TiO2 nanobeads and TiO2 P25, for Gd‐doping up to 10%. Cellular internalization and biocompatibility of TiO2@x Gd NBs are tested in vitro on MG‐63 human osteosarcoma cells, showing full biocompatibility. After photoactivation of the particles, anticancer trace by means of ROS photogeneration is observed just after 3 min irradiation.  相似文献   
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