Research on the Speech Coding Algorithm at 1200bit/s

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自制螺旋叶片下料的实用计算新方法

采用螺旋叶片下料经验公式解决了传统的螺旋叶片下料计算方法复杂的难题。经验公式计算叶片下料圆环外径时,仅需已知螺旋外径和螺距;对同一规格的螺旋,无论螺旋轴直径如何取值,下料圆环外径值唯一。经验公式突破了传统理论,计算简便,实用性强。     

马格磨齿机液性胀胎心轴的精度分析

本文从应力变形的角度分析了液性胀胎心轴受力后外径不能复原的原因和所采取的修复措施,以阻止变形的延续,保证进口机床正常运转.     

Visualization of wound periderm and hyphal profiles in pine stems inoculated with the pitch canker fungus Fusarium circinatum

Postpenetration behavior of Fusarium circinatum in stems of pine species was investigated with light and transmission electron microscopy. Two‐year‐old stems of Pinus rigida and P. densiflora were wound‐inoculated with the fungal conidial suspension and subjected to 25°C for up to 30 days. It was common to observe the formation of wound periderm on each pine species, recovering wounded sites with newly formed tissues. The outermost thick layer of wound periderm was pink to red colored with the phloroglucinol‐EtOH staining, indicating heavy deposition of lignin in wound periderm. The cork layers in the wound periderm of the two pine species consisted of cells that were mostly devoid of cellular contents in cytoplasm. The cork cells showed convoluted cell walls with different electron density (lamellations), which was seemingly more prevalent in P. densiflora than P. rigida. Hyphae of F. circinatum appeared normal with typical eucaryotic cytoplasm in P. rigida on ultrathin sections. Meanwhile, hyphae in P. densiflora were found to possess highly vacuolated cytoplasm, implying hyphal weakening and disintegration. Hyphal cytoplasm appeared to be a thin layer between the vacuole and the plasma membrane surrounded by cell wall. In addition, intrahyphal hyphae and concentric bodies were observed in hyphal cytoplasm. These results suggest that the architecture of wound periderm may be responsible for different responses of pine species to the invasion of F. circinatum. Microsc. Res. Tech., 2009. © 2009 Wiley‐Liss, Inc.     

Fe/C复合纳米材料的制备研究

以强酸为絮凝剂，将碱性溶液中的水性中间相沥青絮凝，从而使水性中间相沥青在酸性介质中形成炭基溶胶和凝胶。将此炭基溶胶和硝酸铁溶液混合形成复合溶胶、凝胶，进而采用醇水交换和超临界干燥制备出粒度为5nm-20nm的Fe/C复合纳米材料。考察了硝酸铁和水性中间相沥青的比例，以及热处理条件对Fe/C复合纳米材料织构和结构的影响。利用透射电镜、物理吸附、ICP－AES、X－射线衍射、热重等表征手段对Fe/C复合纳米材料特性和热处理的变化规律进行了研究。结果表明：通过改变炭基溶胶中硝酸铁的加入量可以制备不同铁含量的Fe/C复合纳米材料；在惰性气氛下，于较低温度热处理时，Fe/C复合纳米粉中铁是以Fe2O3的形式存在，热处理温度升高（900℃）后Fe2O3被还原为单质铁，且金属颗粒团聚长大，在高温（1300℃）时，铁以Fe3C的形式存在，颗粒进一步长大且有部分炭石墨化。在还原性气氛下，在300℃－500℃热处理范围内，随温度的升高铁被还原为单质铁。     

沥青环氧树脂重防腐涂料的研制

利用环氧树脂改性煤焦沥青涂料,以达到它的重防腐性及使沥青涂料的软化温度提高到80℃以上,能在常温下很快干燥,从而扩大沥青涂料的应用范围。     

透气防毒服用活性微球炭孔结构及其吸附性能

在实验室条件下研制了透气防毒服用石油沥青基球形活性炭（PSAC），采用扫描电子显微镜（SEM）对其形貌进行了观察，通过BET测定对PSAC的孔结构进行了表征，同时以苯和四氯化碳为吸附质研究了PSAC静态吸附性能，并与普通粒状活性炭（GAC）进行对比，比较了PSAC和GAC的二次吸、脱附性能．实验结果表明，PSAC的孔径分布主要以微孔为主，PSAC的吸、脱附速度较快，再生性能优异，是一种高性能的炭质吸附材料．     

Aspects of BMP‐2 binding to receptors and collagen: Influence of cell senescence on receptor binding and absence of high‐affinity stoichiometric binding to collagen.

On the basis of their osteoinductive properties bone morphogenetic proteins (BMPs) are used today in clinical therapy such as the treatment of spinal disorders or healing defects in tibia fractures. A major biochemical function of these molecules is their binding to a large number of other proteins to fulfil their biological role. Two of these BMP‐binding proteins are the cellular BMP‐receptor and the collagen molecule which has been implicated as a specific BMP binding protein from the beginning of BMP‐2 research. These two molecules are the subject of this paper. In receptor binding one must distinguish between the binding function (θ) and the state function (r). The binding function describes the equilibrium between effector (e.g. BMP‐2) and the receptor, whereas the state function describes the change in receptor activation elicted by the effector resulting in downstream effects such as the induction of alkaline phosphatase. In studies on the state function of rhBMP‐2 binding to MC3T3‐E1 cells it will be shown that the binding affinity of the receptor decreases fivefold in a highly significant manner (p <0.0002, n = 10, duplicate assays) with the serial passage number from 1.7 ± 0.3 nM as measured with passage 5 cells to 8.9 ± 1.5 nM as measured with passage 10 cells. Since the serial passage model of MC3T3‐E1 cells is a model of senescence it is concluded that the affinity of the rhBMP‐2 receptor interaction decreases with senescence i.e. age. This may have important consequences for the age dependent dosage of rhBMP‐2 in the clinic. In a second series of experiments it will be shown that contrary to widespread belief, BMP‐2 does not show a high affinity stoichiometric binding to collagen as measured by affinity chromatography on collagen Sepharose and in solution by gel filtration. A review of the literature and evaluation of binding stoichiometry, interestingly supported our finding since the calculated stoichiomerties indicate a binding of 10^‐3 to 10^‐4 mol BMP/mol tropocollagen. It is suggested that collagen is substituted by porous calcium phosphates and metals as carriers for BMP applications.     

不同方法制备的螺旋线慢波组件的散热性能的研究

利用电阻温度系数法对冷弹压法、缠钼带热挤压法、石墨热挤压法、磁控溅射覆膜法及新型的无变形热挤压法制备的慢波组件散热性能进行了实验研究,结果表明石墨热挤压法、磁控溅射覆膜法和无变形热挤压方法比冷弹压法和传统的缠钼带热挤压法制备的慢波组件散热性能强许多.传统的石墨热挤压法可与无变形热挤压法制备的组件的散热能力相比拟,但石墨热挤压法会引起慢波组件的两次变形,使慢波组件的微波反射点增多增强,溅射镀膜法比无变形热挤压法制备的慢波组件散热性能强一些,但由于焊接法工艺的复杂性降低了其优势.这些结果为制备散热性能强的慢波组件提供了有益的实验结果.     

Absolute pitch: Frequency-range discriminations in pigeons (Columba livia)--comparisons with zebra finches (Taeniopygia guttata) and humans (Homo sapiens).

Absolute pitch (AP) is the ability to classify individual pitches without an external referent. The authors compared results from pigeons (Columba livia, a nonsongbird species) with results (R. Weisman, M. Njegovan, C. Sturdy, L. Phillmore, J. Coyle, & D. Mewhort, 1998) from zebra finches (Taeniopygia guttata, a songbird species) and humans (Homo sapiens) in AP tests that required classification of contiguous tones into 3 or 8 frequency ranges on the basis of correlations between the tones in each frequency range and reward. Pigeons' 3-range discriminations were similar in accuracy to those of zebra finches and humans. In the more challenging 8-range task, pigeons, like zebra finches, discriminated shifts from reward to nonreward from range to range across all 8 ranges, whereas humans discriminated only the 1st and last ranges. Taken together with previous research, the present experiments suggest that birds may have more accurate AP than mammals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)