Interpreting the input admittance of violins and guitars

The most widespread vibration measurement on musical instrument bodies is of the point mobility at the bridge. Analysis of such measurements is presented, with a view to assessing what range of information could feasibly be extracted from the corpus of data. Analysis approaches include (1) pole-residue extraction; (2) damping trend analysis based on time decay information; (3) statistical estimates based on SEA power-balance and variance theory. Comparative results are shown for some key quantities. Damping trends with frequency are shown to have unexpectedly different forms for violins and for guitars. Linear averaging to estimate the "direct field" component gives a simple and clear visualisation of any local resonance behaviour near the bridge, such as the "bridge hill", and reveals some violins that show a double hill, while viols show only weak hills, and guitars none at all. © S. Hirzel Verlag · EAA.

中国有壳肉足虫(原生动物)五新纪录描述

描述了采自云南、湖北和广东的5种有壳肉足虫,隶属原生动物亚界,肉鞭门,叶足纲,表壳目,均为国内新纪录种:非游巧装表壳虫Arcella artocreaaplanata Grospietsch,1954;具角肋表壳虫A.costata angulosa(Perty)Playfair,1918;拟普通盘状表壳虫A.discoides pseudovulgaris Deflandre,1928;光滑弯凸表壳虫A.gibbosa laevis Deflandre,1928;球形叉口砂壳虫Difflugia gra

不同波段紫外光对微囊藻毒素光降解的影响

为优化光降解法去除饮用水中的微囊藻毒素,分别用UVA(l=300~400nm)和UVC(l=253.7nm)2种紫外光源研究了紫外光波长对MC-RR降解效率的影响.结果表明,不同波段的紫外光具有不同的催化效率和降解中间产物.在UVA下照射12h后,MC-RR仍有30%~50%残余,同时产生2种几何异构体4(Z)-Adda-MC-RR和6(Z)-Adda-MC-RR,且二者在整个反应过程中保持恒定的比例.而在UVC下,MC-RR除生成2种异构体外,还生成中间产物[三环-Adda]MC-RR,在0.850mW

中华鲟、白鲟组织生化成分分析初报

<正> 中华鲟(Acipenser sinensis Cray)隶属鲟形目、鲟科,在生态类群中属河海洄游鱼类,主要分布于我国长江,也见于渤海(烟台)、黄河下游、钱塘江、闽江及珠江等水域。白鲟(Psephurus gladius Martens)隶属鲟形目、白鲟科,也是一种河海洄游性鱼类,主要分布在长江水系中,自四川宜宾至江苏崇明,有时见于大型湖泊(如洞庭湖)。对于这两种我国特有、珍稀、大型的经济鱼类的形态,解剖、地理分布及生态等方面许多研究者曾作过大量的工作,积累了系统的资料(张春霖1928、伍献文192

关于阿尔及利亚西部人体内侵袭水蛭病的研究

<正> 人体内侵袭水蛭病是一种危害人体健康的寄生虫病。在Craig和Faust的“临床寄生虫学”一书中列举了Masterman(1908)和Manson(1903)报道的由于出血过多和喉、气管阻塞导致死亡的例子。Messioger(1924)报道的一妇女因声带受侵袭而产生痉挛性咳嗽和脉搏跳动微弱以及Woolnougb(1928)报道的一三岁和另一十岁半的澳大利亚女孩阴道因水蛭咬伤而出血不止。此病在我国南方广大农村也很普遍,最早金大雄(1941,1949)报道过贵州省和云南省人鼻中发现的水蛭。湖北省兴山县张

High-performance bowing machine tests of bowed-string transients

The development is described of a computer-controlled bowing machine that can bow a string with a range of gestures that match or exceed the capabilities of a human violinist. Example measurements of string vibration under controlled bowing conditions are shown, including a Schelleng diagram and a set of Guettler diagrams, for the open D string of a cello. For some results a rosin-coated rod was used in place of a conventional bow, to provide quantitative data for comparison with theoretical predictions. The results show qualitative consistency with the predictions of Schelleng and Guettler, but details are revealed that go beyond the limitations of existing models. © S. Hirzel Verlag · EAA.

无线自组网络中基于簇结构的安全方案

无线自组网络是一种不需要基础通信设施的自组织网络，正得到越来越多的应用．当前自组网络的安全性研究正成为一个热点．对基于簇结构的自组网络进行了安全分析，并且针对存在的安全问题提出了新的安全解决方案．主要贡献在于：①提出了一个保护簇首的安全机制；②针对节点簇间漫游的安全隐患，提出一个基于请求的节点信息共享机制，并给出了相应的算法．对该方案进行了仿真实验，结果显示，该方案具有充分的可行性．与已有方案相比，该方案具有较完善的安全机制，网络性能也较好．

Identification of a quasiparticle band in very neutron-rich Zr-104

The high spin levels of a very neutron-rich Zr-104 nucleus have been reinvestigated by measuring the prompt. rays in the spontaneous fission of Cf-252. The ground-state band has been confirmed. A new sideband has been identified with a band-head energy at 1928.7 keV. The projected shell model is employed to investigate the band structure of Zr-104. The results of calculated levels are in good agreement with the experimental data, and suggest that the new band in Zr-104 may be based on the neutron nu 5/2(-)[532] circle times nu 3/2(+)[411] configuration.

The Compact Pulsed Hadron Source: A Design Perspective

During the past. decades, large-scale national neutron sources have been developed in Asia, Europe, and North America. Complementing such efforts, compact hadron beam complexes and neutron sources intended to serve primarily universities and industrial institutes have been proposed, and some have recently been established. Responding to the demand in China for pulsed neutron/proton-beam platforms that are dedicated to fundamental and applied research for users in multiple disciplines from materials characterization to hadron therapy and radiography to accelerator-driven sub-critical reactor systems (ADS) for nuclear waste transmutation, we have initiated the construction of a compact, yet expandable, accelerator complex-the Compact Pulsed Hadron Source (CPHS). It consists of an accelerator front-end (a high-intensity ion source, a 3-MeV radio-frequency quadrupole linac (RFQ), and a 13-MeV drift-tube linac (DTL)), a neutron target station (a beryllium target with solid methane and room-temperature water moderators/reflector), and experimental stations for neutron imaging/radiography, small-angle scattering, and proton irradiation. In the future, the CPHS may also serve as an injector to a ring for proton therapy and radiography or as the front end to an ADS test facility. In this paper, we describe the design of the CPHS technical systems and its intended operation.

水稻和稗草共生土壤微生物生物量碳及酶活性的变化

以稻田稗草、化感水稻PI312777和普通水稻辽粳9为试材,研究了田间稗草和水稻1∶1共生条件下,土壤微生物生物量碳及脱氢酶、脲酶和转化酶活性的变化.结果表明:在稗草的干扰下,化感水稻PI312777根区土壤微生物生物量碳含量比单作减少了50.52%(P<0.01),而行间土壤微生物生物量碳含量增加;普通水稻辽粳9根区土壤微生物生物量碳含量比单作减少了38.99%(P<0.01),但其行间土壤微生物生物量碳含量无明显变化.两个水稻品种根区土壤脱氢酶活性均被显著抑制(P<0.05),下降率都在20%以上;PI312777根区土壤脲酶和转化酶活性均被显著促进(P<0.01);而辽粳9根区土壤转化酶活性也被显著抑制(P<0.01),但脲酶活性无明显变化.化感水稻根区土壤微生物生物量碳含量的显著减少及脲酶、转化酶活性的增加是其化感特性的表现,表明土壤微生物和酶均参与了水稻和稗草的种间作用,化感水稻具有抗稗草干扰的明显优势.

拓展城市功能促进农村发展

<正> 几年来,各地都开展农业产业结构调整,根据各自条件,努力建立适应市场需求,促进农民增收和农村经济发展的农业结构新格局。然而,农村人口占全国人口70％,约70％农村劳动力从事初级农业生产,有限的农业经济资源潜力难以从根本上改变农村经济发展缓慢和农民收入较低的局面。随着我国加入世贸组织,农业面临来自国际市场更大的压力和挑战,只对