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%% WADCP PACKAGE 0.3 -- function [zeta_vdB,zeta_ddB,Cst_sdt]=sdt_absorption
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%%
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%
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% Backscatter signal processing toolbox
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%
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% _Written by C. Tessier, IFREMER |contact : caroline.tessier@ifremer.fr
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function [zeta_vdB,zeta_ddB,Cst_sdt]=sdt_absorption(f,rm)
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% global f
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%%
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% * sediment and water properties to evaluate sigbar and sigbartot *
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% a_s=40;% default particules diameter [?m]
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rm=rm/2*10^-6; %radius en meters needed !!
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% rho_s=1160; % default individual particles density [kg/m^3]
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% c_s=4500; % default sound celerity in particles [m/s]
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% rho_w=1024; % default water density [kg/m^3]
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% c0=1505; % default sound celerity in water [m/s]
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%mod?le de porosit? particules ?l?mentaires
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rb=rm-3*10^-6;
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rc=rm+3*10^-6;
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u_g=2*rb;
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rho_w=1024;
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rho_g=2700;
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N=1-0.63*(rm^3/rc^3);
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rho_s=N*rho_w+(1-N)*rho_g;
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Kw=2.25*10^9;
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Kg=1.47*10^10;
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c_s=sqrt(Kw*Kg/(rho_s*(N*Kg+(1-N)*Kw)));
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% mu0=2*10^9;
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% u0=1000*10^-6;
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% c_s=sqrt(c0^2+(mu0/rho_s)*(u_g/u0)^(1/3));
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%th?orie fractale
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% rb=rm-3*10^-6;
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% % rc=rm+3*10^-6;
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% u_g=2*rb;
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% rho_w=1024;
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% rho_g=2700;
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% rho_s=(rho_g-rho_w)*(4*10^-6/(2*rm));
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% N=(rho_s-rho_g)/(rho_w-rho_g);
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% Kw=2.25*10^9;
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% Kg=1.47*10^10;
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% c0=sqrt(Kw*Kg/(rho_s*(N*Kg+(1-N)*Kw)));
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% mu0=2*10^9;
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% u0=1000*10^-6;
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% c_s=sqrt(c0^2+(mu0/rho_s)*(u_g/u0)^(1/3));
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% c_s=4500;
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% prompt = {'a_s : particules mean/equivalent diameter [?m]';'rho_s : particles density [kg/m^3]';'c_s : sound celerity in particles';'rho0 : water density [kg/m^3]';'c0 : sound celerity in water [m/s]'};
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% dlg_title = 'Summary of particles and water characteristics - can be changed by users';
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% num_lines = 1;
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% def = {num2str(a_s);num2str(rho_s);num2str(c_s);num2str(rho0);num2str(c0) };
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% tmp = inputdlg(prompt,dlg_title,num_lines,def);
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% a_s=eval(char(tmp{1}));
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% rho_s=eval(char(tmp{2}));
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% c_s=eval(char(tmp(3)));
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% rho0=eval(char(tmp{4}));
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% c0=eval(char(tmp{5}));
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%-----------------------------------
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% rm=rm/2*10^-6; %radius en meters needed!
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v_s=4/3*pi*(rm).^3; %individual volume en m^3
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%-----------------------------------
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% ask user to choose nature of particles (2 default case and one user defined)
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% qst_proc=questdlg('Which kind of particles ?','Particles Caracteristics','Mineral','Zooplankton','User defined','Mineral');
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% switch qst_proc
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% case 'Mineral'
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% id_sed=1;
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% case 'Zooplankton'
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% id_sed=2;
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% case 'User defined'
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% id_sed=3;
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% end
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%
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% % ask user to choose theorical model (1) Thorne or (2) Tessier (from Stanton)
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% qst_proc=questdlg('Which Acoustic Scattering Model ?','Acoustic Scattering Model',...
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% 'Tessier 2006 (all particles)','Thorne 2002 (sand)','Tessier 2006 (all particles');
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% switch qst_proc
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% case 'Thorne 2002 (sand)'
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% id_mod=1;
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% case 'Tessier 2006 (all particles)'
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% id_mod=2;
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% end
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%
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% if ((id_mod==1) & (id_sed~=1))
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% display('!!! WARNING !!! ')
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% display('Acoustic Scattering Model of Thorne valid for MINERAL particles only')
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% end
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% evaluation of scattering cross-sections
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[sigbar,sigbartot]=sigmabar(f,rm,rho_s,c_s,2);
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% sediment caracterisation in the Scatter Index IV : IV=10log10(M*sigbar/rho_s/vs)
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Cst_sdt=10*log10(sigbar/rho_s/v_s);
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%%
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% * sediment absorption constantes *
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%-absorption visqueuse particules zeta_v [Urick,1948]
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lambda=1500/f/1000; % mean wave length
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omega=2*pi*f*1000; %vitesse angulaire (rad/s)
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nu=1.3*10^-6;%viscosite cinematique eau nu (m^2/s)
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beta=(omega/2/nu)^0.5;
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teta=0.5*(1+9./(2*beta.*rm));
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s=(9./(4*beta.*rm)).*(1+1./(beta.*rm));
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gg=rho_s/rho_w;
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zeta_v=(2*pi/lambda*(gg-1)^2)/(2*rho_s)*(s/(s.^2+(gg+teta).^2));
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zeta_vdB=20*log10(exp(1))*zeta_v;
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%-absorption due a diffusion par particules zeta_d
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zeta_ddB=20/2*log10(exp(1))*(sigbartot/rho_s/v_s);
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%-amortissement total du au sediment alpha_s
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%qs=2*(zeta_vdB+zeta_ddB)*M*dR;
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