Synthesizing sound from turbulent field using sound textures for interactive fluid simulati
Speech Synthesis
April 14, 2009
Some Reminders
• Final Exam is next Monday: • In this room • (I am looking into changing the start time to 9 am.) • I have a review sheet for you (to hand out at the end of class).
Perception → Production
• Japanese listeners performed an /r/ - /l/ discrimination task. • Important: listeners were told nothing about how to produce the /r/ - /l/ contrast • …but, through perception training, their productions got better anyway.
Exemplar Categorization
1. Stored memories of speech experiences are known as traces. • Each trace is linked to a category label.
2. Incoming speech tokens are known as probes. 3. A probe activates the traces it is similar to. • • Note: amount of activation is proportional to similarity between trace and probe. Traces that closely match a probe are activated a lot; • Traces that have no similarity to a probe are not activated much at all.
科技英语阅读 翻译词汇
Lead in: Brainstorming
What’s …? 运动 movement /力force /动能和功 动能和功kinetic 力 动能和功 energy and work /势能 势能potential energy/ 能量守 势能 恒conservation of energy /引力 gravitation /声 引力 声 波 sound wave /振动 oscillation / 流体 fluid / 波 振动 wave/ 温度 温度temperature /热量 heat /电荷 电荷electric 热量 电荷 charge /电场 electric field 电场
Lead in: Brainstorming
What’s …? 密码 cipher / 违规 breach / 网桥 bridge / 蛮力攻 击 brute-force attack / 证书序列号 certificate serial number / 询问 challenge / 选择明文攻击 chosen-plaintext attack / 破译 code breaking / 线间进入 between-the-lines entry / 攻击者 attacker / 密码学 cryptology / 解密 decryption / 授权 delegation / 加密 encryption
Lead in: Brainstorming
What’s …? 绝对补集 absolute complement / 代数 algebra / 代数式 algebraic expression / 代数方程 algebraic equation / 代数不等式 algebraic inequality / 任意常数 arbitrary constant / 数组 array / 底数；基数 base number / 连续函数 底数； continuous function / 函数 function / 复合函数 function of function / 函数记号 函数记号functional notation / 集合 集合aggregate / 子集 subset
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基于相位调控的超高透射声学超表面及其应用
基于相位调控的超高透射声学超表面及其应用田野;左淑毓;程营;刘晓峻【摘要】声学超表面可以灵活有效地对声波进行调控,实现多种新颖的现象和功能,在诸多声波调控领域有潜在的应用前景.该文引入了一种镀膜型迷宫结构单元,可以提供全范围(0～2π)的突变相位,具有高效的透射率(～100％)和较好的鲁棒性.基于相位调控,可利用镀膜型迷宫结构单元构建出超高透射超表面,实现异常声折射、声聚焦、声束沿任意凸轨迹弯曲传播以及声成像等应用.【期刊名称】《应用声学》【年(卷),期】2018(037)005【总页数】10页(P691-700)【关键词】超表面;声波调控;相位调控;迷宫结构;高透射【作者】田野;左淑毓;程营;刘晓峻【作者单位】南京大学物理学院南京 210093;南京大学物理学院南京 210093;南京大学物理学院南京 210093;南京大学物理学院南京 210093【正文语种】中文【中图分类】O421 引言作为低维化的声学超材料[1]，声学超表面近年来逐渐得到了人们的广泛关注[2]。
声学超表面一般是由多种微结构单元按特殊序列排列在一起形成的具有亚波长厚度的平面型超材料体系，它可以灵活有效地对声波进行调控，实现多种新颖的声学现象和功能。
相对于体积型声学超材料，声学超表面具有结构简单、紧凑、效率高、体积小、易加工等特点。
目前声学超表面研究主要集中在反射调控、透射调控以及吸声等三个领域[2]。
对于透射超表面，目前已经实现了异常折射、负折射、体波向表面波转换、声束自弯曲、超稀疏隔声、生成螺旋声场、多路复用信号传输、声成像、模拟数学运算、非对称传输、全向通风声屏障等诸多功能和应用[3−16]，在医疗、通信、检测、军事乃至国计民生的各方面均具有广阔的应用前景。
随着广义折射定律理论的提出[17]及其向声学领域的拓展[18−19]，相位调控已成为声学超表面研究的重要手段。
因为结构相对简单、易加工等特点，迷宫结构单元可实现透射声学超表面的相位调控[3−4,11]。
Field
Field II仿真超声换能器声场原理昨天开组会⼤家讨论问题，有⼏个疑问被提出来了：1. Field II主要建模算法⽤C代码实现。
2. ⼆维压电陶瓷换能器阵列和CMUT⼆维换能器阵列有什么区别？本⽂只讨论第⼀个问题，第⼆个另⽂细述。
Field II代码和⼤⼆⼩师弟讨论Field II建模CMUT换能器时，发现Field II的Matlab代码只是来做参数配置和调⽤函数的，这些函数编译为可执⾏⽂件，主要的建模算法是⽤C代码实现，⽽这个代码并没有开源。
我给Dr. Jensen发了封邮件要C代码，但愿能回复我。
建模⽅法使⽤空间冲击响应（spatial impulse response）的原理，依托于超声场的线性系统理论。
发射时，当换能器被狄拉克delta函数激发后，空间中每个点的声场是关于时间的函数。
声场可以通过空间冲激响应和激发函数卷积得到。
接收时，把换能器激发函数和发射孔径的空间冲击响应、接受孔径的空间冲击响应卷积得到接收响应，通过换能器的机械电⼦传递函数得到接收电压曲线。
软件使⽤如果只是⽤Field II仿真声场，可以直接调⽤Matlab函数，配置参数，⽐如探头的物理参数（阵元类型，数量，尺⼨，探测物，接收孔径等），然后得到接收信号，可以拿来波束合成。
我们⽤⼀段⽰例程序来产⽣⾎流的接收波束信号如图。
% This examples shows how the procedures can be used for making flow data from a number of scatters in a tube.% Example of use of the new Field II program running under Matlab%% This example shows how flow can simulated%% This script assumes that the field_init procedure has been called%% Example by Joergen Arendt Jensen, March 22, 2011.% Generate the transducer apertures for send and receivef0=3e6; % Transducer center frequency [Hz]fs=100e6; % Sampling frequency [Hz]c=1540; % Speed of sound [m/s]，⼈体内声⾳平均速度lambda=c/f0; % Wavelengthelement_height=5/1000; % Height of element [m]kerf=0.1/1000; % Kerf [m]focus=[0 0 70]/1000; % Fixed focal point [m]% Generate apertureaperture = xdc_linear_array (128, lambda/2, element_height, kerf, 1, 1,focus); % Set the impulse response and excitation of the emit apertureimpulse_response=sin(2*pi*f0*(0:1/fs:2/f0));impulse_response=impulse_response.*hanning(max(size(impulse_response)))'; xdc_impulse (aperture, impulse_response);excitation=sin(2*pi*f0*(0:1/fs:8/f0));xdc_excitation (aperture, excitation);% Set the seed of the random number generatorrandn('seed',sum(100*clock))% Initialize the ranges for the scatterers，⾎管⾥⾯的物质% Notice that the coordinates are in metersx_range=0.015; % x range for the scatterers [m]y_range=0.015; % y range for the scatterers [m]z_range=0.015; % z range for the scatterers [m]z_offset=0.70; % Offset of the mid-point of the scatterers [m]R=0.005; % Radius of blood vessel [m]% Set the number of scatterers. It should be roughly% 10 scatterers per resolution cellc=1540; % Ultrasound propagation velocity [m/s]f0=3e6; % Center frequency of transducer [Hz]lambda=c/f0;N=round(10*x_range/(5*lambda)*y_range/(5*lambda)*z_range/(lambda*2)); disp([num2str(N),' Scatterers'])% Generate the coordinates and amplitude% Coordinates are rectangular within the range.% The amplitude has a Gaussian distribution.x=x_range*(rand(1,N)-0.5);y=y_range*(rand(1,N)-0.5);z=z_range*(rand(1,N)-0.5);% Find which scatterers that lie within the blood vesselr=(y.^2+z.^2).^0.5;within_vessel= (r < R)';% Assign an amplitude and a velocity for each scattererv0=0.5; % Largest velocity of scatterers [m/s]velocity=v0*(1-(r/R).^2).*within_vessel';blood_to_stationary= 0.1; % Ratio between amplitude of blood to stationary tissue amp=randn(N,1).*((1-within_vessel) + within_vessel*blood_to_stationary);% Calculate a suitable Tprftheta=45/180*pi;f_max=2*v0*cos(theta)/c*f0;fprf=3*f_max;Tprf=1/fprf; % Time between pulse emissions [s]Nshoots=128; % Number of shoots% Find the response by calling fieldfor i=1:Nshootsi% Generate the rotated and offset block of samplexnew=x*cos(theta)+z*sin(theta);znew=z*cos(theta)-x*sin(theta) + z_offset;scatterers=[xnew; y; znew;]' ;% Calculate the received response[v, t1]=calc_scat(aperture, aperture, scatterers, amp);% Store the resultimage_data(1:max(size(v)),i)=v;times(i) = t1;% Propagate the scatterers and alias them% to lie within the correct rangex=x + velocity*Tprf;outside_range= (x > x_range/2);x=x - x_range*outside_range;end% Here the display of the data% Here the display of the data is insertedplot(image_data)。