二维频域波束形成方法

一般来讲，无论雷达或声纳从基阵接收的信号均是多维信号，本文将在二维频率域对窄带传输信号进行分析与描述，研究线列阵的波束形成问题，根据分析结果并考察了几种特例。     

Fe40—45Cr30—35Co20—25Mo0—4Zr0—2合金微观结构对矫顽力的影响

研究了高矫顽力型FeCrCo合金的磁性和微观结构.实验结果表明，适当的合金成分及热处理 条件可以明显提高FeCrCo合金的矫顽力.通过透射电镜、x射线衍射等手段得出结论：主体元 素含量的提高和微量元素的掺杂可以有效地控制相的组成，磁场热处理导致强磁性相和弱磁 性相的分离，回火后形成起磁硬化作用的调幅结构.该调幅结构中较大的两相成分差有利于 提高FeCrCo合金的矫顽力. 关键词： 矫顽力 调幅分解 磁场热处理 两相结构 成分差     

Palladium-catalyzed Suzuki-Miyaura reaction using aminophosphine as ligand

Suzuki-Miyaura cross-coupling reaction has been achieved under the catalysis of Pd(OAc)₂ in the presence of readily accessible and easily tunable aminophosphine ligands with high efficiency under mild reaction condition.     

新疆石头花属植物分类研究及其生态地理分布

Gypsophila L.中国有25种。1980年出版的“新疆植物检索表”第二册中收载了5种。“新疆植物名录”中收载了4种。中国高等植物图鉴补编(1:336,1982)收载了11种。本文按现行新疆维吾尔自治区的行政范围进行整理研究,共收载了12种,其中发现全国分布新纪录2种—G.capitata M.B.,G.sericea(Ser.)Kryl.新疆分布新纪录1种—G.licentiana Hand—Mazz。本文阐明了新疆境内石头花属植物的生态、地理分布特点。在新疆境内本属植物的区系地理成分主要是亚洲中部的草原和荒漠成分。     

Studies on the chemical constituents of Chinese azalea: I. The structure of rhodomollein-I,a new toxic diterpenoid

Two unknown toxic diterpenoids, rhodomollein-I and rhodomollein-II, and the known rhodojaponin-III, have been isolated from Chinese azalea (Ericaceae, Rhododendron molle G. Don). rhodomollein-I, C₂₀H₃₂O₆, colorless thin needles, [α]_D²⁰ ?6.65 (c 3.76 × 10^?2, EtOH), m. p. 241–242.5 °C. Its structure has been established as 1 through spectral analysis of ¹³C NMR, ¹H NMR, MS, IR and UV. Moreover, its stereostructure was unambiguously identified from the different threshold level line of ¹H-¹H NOESY.     

Passively Q-switched Nd:GdVO4 solid-state lasers with stabilized repetition rates

By modulating the pump current, we developed a passively Q-switched diode-pumped all-solid-state laser with a repetition rate stabilized up to 10-7. It was experimentally demonstrated that the stability could sustain for an arbitrarily long time. Moreover, the stabilized repetition rates which were synchronized with different modulating frequencies were tuneable in a wide range, by adjusting the period of the pumping cycle only. The output single-pulse energy was also stabilized, which was independent on the pump power after reaching a saturable value.     

Fast Encoding Method for Image Vector Quantization Based on Multiple Appropriate Features to Estimate Euclidean Distance

The encoding process of finding the best-matched codeword (winner) for a certain input vector in image vector quantization (VQ) is computationally very expensive due to a lot of k-dimensional Euclidean distance computations. In order to speed up the VQ encoding process, it is beneficial to firstly estimate how large the Euclidean distance is between the input vector and a candidate codeword by using appropriate low dimensional features of a vector instead of an immediate Euclidean distance computation. If the estimated Euclidean distance is large enough, it implies that the current candidate codeword could not be a winner so that it can be rejected safely and thus avoid actual Euclidean distance computation. Sum (1-D), L₂ norm (1-D) and partial sums (2-D) of a vector are used together as the appropriate features in this paper because they are the first three simplest features. Then, four estimations of Euclidean distance between the input vector and a codeword are connected to each other by the Cauchy–Schwarz inequality to realize codeword rejection. For typical standard images with very different details (Lena, F-16, Pepper and Baboon), the final remaining must-do actual Euclidean distance computations can be eliminated obviously and the total computational cost including all overhead can also be reduced obviously compared to the state-of-the-art EEENNS method meanwhile keeping a full search (FS) equivalent PSNR.     

Calculation and Optimization of the Effective Extinction Cross Section of the Spherical Cold Obscuring Smoke

The smoke is often generated in the battlefield by the smoke ammunition to protect the personnel and equipment against the enemy's optoelectronic systems. The effective extinction cross section is an important parameter of the infrared smoke ammunition. In this paper, the relationships between the effective extinction cross section of a cloud of spherical smoke and the mass of the smoke agent, the radius of the screening smoke and the mass extinction coefficient are discussed. The expressions of the maximal effective extinction cross section is derived. This research will help us to achieve optimal design of the smoke ammunition and to appropriately evaluate the effectiveness of the smoke. Examples are given for two kinds of obscurants.     

低声阻抗复合压电陶瓷的研究及应用

本文研究了我们所配制夹心结构复合压电材料低声阻抗的特性。实验表明，夹心复合压电陶瓷材料的声阻抗，与所用陶瓷材料的种类，气孔率，孔径，样品厚度以及工艺制备过程有关。实验证明，研制特定阻抗的材料是可行的，最后，用研制的新材料成功地应用于混凝土、Ｃ／Ｃ复合材料等非金属材料的超声检测中。