如何在演唱中较好地掌握共鸣

共鸣是歌唱中较难掌握的技巧，也是表现歌曲风格特点的关键，歌唱共鸣的较好掌握，不仅能使演唱者呼吸通畅、位置统一，而且能更好地表达歌曲内涵，让人赏心悦目。     

一种基于马尔科夫链的水下频谱预测方法

随着现代信息技术和海洋开发技术的飞速发展,人们对水声通信的需求日益增加。本文针对水声信道可用通信带宽有限、传输时延大的特性,提出了一种基于马尔科夫链的认知水声通信中的频谱预测方法,并用MATLAB对其性能进行了仿真。仿真结果显示与无频谱预测及随机接入情况下相比,本文所提方法可以合理地动态分配水下的频谱资源、有效的减少数据碰撞概率,从而提高频道利用率以及节点接入频道的准确率。     

广东河源28.8kWp单轴和双轴跟踪并网光伏系统研究

介绍了广东河源金太阳示范项目中容量为28.8 kWp单轴、双轴跟踪光伏系统的配置情况和控制原理,并对比了单轴跟踪系统、双轴跟踪系统与固定系统的发电量。统计结果表明单轴和双轴跟踪系统的发电量比固定系统分别提高了18.6%和38.9%,证明跟踪系统能够明显地提高光伏组件的单位发电量,具有很高的应用价值。     

浅水多途水声通信空间冲激响应峰脊陡变效应

水声通信信道复杂,浅水水声通信的多途效应导致信道衰落,信号在幅度和相位空间上形成空间增益,对浅水多途水声通信空间增益冲激响应的准确建模,能改进通信质量。提出一种基于垂直线列阵结构的水声信道多径特性分析方法,得出浅水多途水声通信的空间冲激响应的峰脊陡变效应。构建浅水多途水声信道模型,计算时变特性的自相关函数,得到水声多径信道的脉冲响应,最后得出浅水多途水声通信的空间冲激响应增益改善模型。仿真实验表明,该方法能提高了浅水通信系统的时间压缩和空间聚焦特性,可以有效地重组多径、拟制码间干扰,提高通信质量。     

山西碛口黑龙庙山门戏台声学问题初探

山西临县碛口古镇黑龙庙的山门戏台具有“窑洞内外不一样”、“戏台唱戏不费力”和“山西唱戏陕西听”的奇妙声学效应。通过实地考察,运用声音的直射、反射、共振等声学原理,从声源、声音传播和接收三个角度对黑龙庙山门戏台的声学效应进行探讨和分析。文章认为“窑洞内外不一样”是庙院内窑洞对声音的汇聚、共振及扩散传播的表现形式,“戏台唱戏不费力”是庙院内声音混响的反映,“山西唱戏陕西听”是庙院声音在庙院结构及其环境等因素综合作用下形成的声学效应。     

Conceptual Model for the Replacement of the Horn of a Nineteenth Century Phonograph

ABSTRACT

3D printing of missing parts of a cultural heritage artifact opens many possibilities and extends the challenges in the processes of intervention on cultural heritage assets. However, restoring these objects may not only mean the replacement of a missing element from its esthetic point of view, but restoring the function for which objects were created. In these processes, the replica of the object must be exact and of quality, but also specific. In this sense, the presented work is a multi-disciplinary attempt to reproduce the missing horn of a phonograph dated to the late nineteenth century. This phonograph belongs to the collection of the ‘Vicente Miralles Segarra’ Telecommunication Museum of the Universitat Politècnica de València. The objective was to recover its esthetic, didactic, and functional levels, i.e restoring its ability to emit sound. To this end, several models were printed with different materials, and the quality of the recorded sound with the different horns was evaluated, assessing their similarity to that obtained from an original horn.     

HERIe: A Web-Based Decision-Supporting Tool for Assessing Risk of Physical Damage Using Various Failure Criteria

ABSTRACT

HERIe is a web-based decision-supporting software tool to facilitate the management of collection environments by precise assessment of climate-induced risk of physical damage to vulnerable objects. The software translates the relative humidity and temperature data recorded in the environment of the analysed object into a strain history experienced by it, and estimates the risk of physical damage using selected failure criteria. As all information is pre-calculated for the user, no engagement in complex and time-consuming numerical simulations is required. HERIe is available for testing at herie.mnk.pl. Detailed information on the methodologies used by the software is available at the above website which also contains tutorial climates. The current work aims at refining HERIe by selecting the damage criteria not only from laboratory studies but also from direct monitoring damage accumulation in objects, especially using the acoustic emission method. The software has been expanded to include moisture-induced response of parchment to support managing environments in libraries and archives.     

天津话上声的两条"变调规则"辨析

一、引言天津话是北方方言,自20世纪80年代李行健、刘思训在《中国语文》上发表有关天津话连读变调的文章以来[1],天津话的连读变调现象一直是国内外语言学界讨论的热点。人们从语音实验、音系分析、社会调查等不同的角度,对天津话的连读变调现象进行分析、探讨,提出了各自的主     

燃烧室声学特性模拟实验及应用

介绍了补燃循环液体火箭发动机燃烧室声学特性模拟实验原理、方法和在发动机高频燃烧不稳定性研究中的应用。模拟实验系统包括激励源、模拟燃烧室和声学特性测量系统等。激励源为扬声器或者喷嘴气流。模拟燃烧室是依据高频燃烧不稳定性特征设计、与实际燃烧室有相同固有频率的缩尺件。声学特性测量系统包括麦克风、频谱分析仪和示波器等。模拟实验主要用于研究特定燃烧室的声学特性，研究给定燃烧室结构下喷嘴和隔板的优化设计，研究高频燃烧不稳定性的机理。     

碳纤维复合材料板振声特性分析及优化

为了研究结构几何参数及铺层参数改变对碳纤维复合板的振动声辐射特性影响,利用有限元/边界元法计算了碳纤维复合材料板的振动声辐射特性参数,并以降低结构振动噪声为目标对其进行了优化分析。研究表明:加筋、增加筋数和增加铺设层数能降低结构的辐射噪声。3 种铺层角度中,[0°/90°/45°]辐射噪声最低。在第一阶波峰处,优化后声功率值相比优化前减少了大约4 dB。研究结果可为降低结构辐射噪声提供理论依据。