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海莲红树林的生物量和生产力 总被引:11,自引:1,他引:11
本文是海南东寨港红树林研究的一部分。主要讨论55龄海莲群落的生物量和生产力。测定结果表明:海莲群落的植物生物量为 42.03kg/m~2,其中地上部为24.85 kg/m~2,地下部为 17.18kg/m~2,地下部占总量的40.9%。1983年初级净生产量为2.95kg/m~2·a,其中叶等年凋落物为 1.31 kg/m~2·a,占总量的44.4%。大量的凋落物有利海湾河口水产渔业的发展。 相似文献
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WANG TingTing LI ChunYan ZHENG XianFeng & CHEN Yang Hefei National Laboratory for Physical Sciences at Microscale Department of Chemical Physics University of Science Tech-nology of China Hefei China 《科学通报(英文版)》2007,(5)
Resonance-enhanced multiphoton ionization (REMPI) spectra of N32S and N34S have been recorded in the range of 35700―40200 cm?1. The radical was generated by a pulsed dc discharge of a mixture of SF6 and N2 under a supersonic free jet condition. All the 16 observed bands of N32S radicals have been as-signed, among which 12 bands belong to three transition progressions (v'=0-4, 0), (v'=1-4, 1) and (v'=2-4, 2) from the X2Π ground state to the B'2Σ upper state and the rest correspond to (9, 0), (10, 0), (11, 0) and (12, 0) bands of B2Π-X2Π transition, respectively. Analysis of the rotationally resolved spectra yields exhaustive spectroscopic constants of both the X2Π ground state and the B'2Σ excited state. The electronic transition bands of the isotopic molecule N34S have been rotationally analyzed for the first time and the rotational constants of the ground and upper states have been determined simultaneously. 相似文献
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带钢拉伸弯曲变形过程的表征是拉伸弯曲矫直工艺研究中的关键,带钢拉伸弯曲变形过程在本质上就是带钢在张力作用下的反复弯曲变形过程.本文建立了可以模拟此变形过程的有限元仿真模型,并对带钢拉伸弯曲变形过程进行了仿真研究,揭示了带钢产生塑性延伸和板形矫正的机理.在此基础上,提出了拉伸弯曲矫直工艺使用制度. 相似文献
225.
Zhen Chen Yuhao Wen Junwei Cao Wenxun Zheng Jiahui Chang Yinjun Wu Ge Ma Mourad Hakmaoui Guodong Peng 《清华大学学报》2015,(1):100-115
With the growing popularity of Internet applications and the widespread use of mobile Internet, Internet traffic has maintained rapid growth over the past two decades. Internet Traffic Archival Systems(ITAS) for packets or flow records have become more and more widely used in network monitoring, network troubleshooting, and user behavior and experience analysis. Among the three key technologies in ITAS, we focus on bitmap index compression algorithm and give a detailed survey in this paper. The current state-of-the-art bitmap index encoding schemes include: BBC, WAH, PLWAH, EWAH, PWAH, CONCISE, COMPAX, VLC, DF-WAH, and VAL-WAH. Based on differences in segmentation, chunking, merge compress, and Near Identical(NI) features, we provide a thorough categorization of the state-of-the-art bitmap index compression algorithms. We also propose some new bitmap index encoding algorithms, such as SECOMPAX, ICX, MASC, and PLWAH+, and present the state diagrams for their encoding algorithms. We then evaluate their CPU and GPU implementations with a real Internet trace from CAIDA. Finally, we summarize and discuss the future direction of bitmap index compression algorithms. Beyond the application in network security and network forensic, bitmap index compression with faster bitwise-logical operations and reduced search space is widely used in analysis in genome data, geographical information system, graph databases, image retrieval, Internet of things, etc. It is expected that bitmap index compression will thrive and be prosperous again in Big Data era since 1980s. 相似文献
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Nonvolatile memories (NVMs) with triple layers of silicon nanocrystals were fabricated with conventional CMOS technology.This paper explores the program/erase performance and reliability of NVMs with three layers of nanocrystals.The results indicate that the nanocrystals in the triple-layer nanocrystal NVM (NCNVM) are difficult to fully charge during the programming process.The programming speed of the triple-layer NCNVMs is quicker than that of single-layer NCNVMs,which means that the second and third layers of nanocrystals in the triple-layer NCNVM affect the charge of the first layer nanocrystals.Reliability tests show that the memory window has little degradation after 1×104 cycles. 相似文献
229.
As a generalization of orthogonal frequency-division multiplexing (OFDM) systems,multi-input multi-output (MIMO) OFDM systems are very sensitive to carrier frequency offset (CFO).This paper proposes a blind CFO estimation method based on power spectrum analysis,which has high bandwidth efficiency and is much less complex.This method can be used to estimate the residual CFO,which is less than half of the subcarrier spacing.The method uses a cosine cost function to get a closed-form CFO estimate.Simulation results illustrate that the method is effective for MIMO OFDM systems. 相似文献
230.
Two characteristics of Chinese mixed traffic invalidate the conventional queuing delay estimates for western countries.First,the driving characteristics of Chinese drivers lead to different delays even though the other conditions are the same.Second,urban traffic flow in China is often hindered by pedestrians at intersections,such that imported intelligent traffic control systems do not work appropriately.Typical delay estimates for Chinese conditions were obtained from data for over 500 vehicle queues i... 相似文献