International Workshop - SMW08 IN SITU MONITORING OF MONUMENTAL SURFACES Florence, 27-29 October 2008 28th October Session 3 Geo-physical and mechanical properties SURFACE CHARACTERIZATION OF FRESCOES BY MEANS OF ACOUSTIC IMAGE DIAGNOSTICS AND DIGITAL IMAGE PROCESSING P. Calicchia, G. B. Cannelli, M. Poscolieri CNR Institute of Acoustics “O. M. Corbino”, Rome Paola Calicchia paola.calicchia@idac.rm.cnr.it 28th October

ACEADD: portable device for NDT of fresco detachments based on the ACOUSTIC ENERGY ABSORPTION evaluation BACK REFLECTION SETTING source S and receiver M in COAXIAL CONFIGURATION and NORMAL INCIDENCE GEOMETRY working distance from the surface is about 0,5m measure of the abs. coeff. by the determination of the transfer function a(w) = 1 - |HS(w)|2 DIRECT EXTRAPOLATION of the surface impulse response hS(t) by means of Cepstrum algorithm signal processing wide band SINE WAVE SWEEP 100Hz ÷ 15kHz it provides 2D and 3D ACOUSTIC ABSORPTION MAPS and ROUGHNESS MAPS for the LOCALIZATION and CHARACTERIZATION of detachments. (G. B. Cannelli, P. Calicchia, US Patent US 6728661 27, European Patent EP 1190243B1") (1) (2) (3) (4) ACEADD – ACOUSTIC ENERGY ABSORPTION DIAGNOSTIC DEVICE 28th October

a(w) MEASURING THE ACOUSTIC ENERGY ABSORPTION COEFFICIENT DETERMINATION OF ACOUSTIC PROPERTIES AND PERFORMANCE OF MATERIALS CHARACTERIZATION AND CERTIFICATION OF MATERIALS, STRUCTURES AND SURFACES EMPLOYMENT OF BOTH LABORATORY AND IN SITU METHODOLOGIES INTERNATIONAL STANDARD METHODS ISO 354:2003 “MEASUREMENT OF SOUND ABSORPTION IN A REVERBERATION ROOM” ISO 13472:2002, “MEASUREMENT OF SOUND ABSORPTION PROPERTIES OF ROAD SURFACES IN SITU” ROAD PAVEMENTS & NOISE BARRIERS ABSORBENT MATERIALS (polyurethane foam, wool, wood, many porous or fibrous materials) ABSORBENT PANELS & STRUCTURES ISO 13472:2002 Part 1: Exended surface method Part 2: Spot method for reflective surfaces, draft version Part 3: Spot method for absorptive surfaces, draft version THE ACOUSTIC ABSORPTION COEFFICIENT 28th October

Reflection coefficient at Normal incidence Z2 – Z1 Z2 + Z1 2 Reflection coefficient at Normal incidence Z2 >> Z1 Z = r c R = 1 ARRICCIO SUPPORT INTONACHINO A detachment is like a vibrating disk or membrane with an enclosed volume of air behind And behaves like an acoustic absorber ACEADD – ACOUSTIC ENERGY ABSORPTION DIAGNOSTIC DEVICE 28th October

Perforated Panel Absorbers Copyright © Andrew Marsh, UWA, 1999. The School of Architecture and Fine Arts The University of Western Australia Porous Absorbers Membrane Absorbers Cavity Absorbers Perforated Panel Absorbers SOUND ABSORPTION IN MATERIALS AND STRUCTURES 28th October

ACEADD – THE MEASURING PROCEDURE 1 - THE PICTURE OF THE FRESCO 2 - THE DEFINITION OF THE ANALYSED AREA 3 - THE CHOISE OF THE SOME REFERENCE POINTS 4 - THE CHOISE OF THE WORKING DISTANCE 5 - THE CONTROL OF THE SCAN UNIT ACEADD – THE MEASURING PROCEDURE 28th October Page 6 6

ACEADD – THE MEASURING PROCEDURE 6 – THE MOTION CONTROL AND THE ACQUISITION (… is it time consuming? LAB INSTR.: 120 pts in 1h, 600 pts in 5h covering 96cm x 76cm with 4cm step) 7 - THE SIGNAL PROCESSING CEPSTRUM ALGORITHM (resolves the reflection peak from the direct signal even when they are superposed in the time history) xi, yi, hi, ti, Hi(w), di, … , imgi, Ti, Tamb, RH% 8 - THE MAX REFLECTION REFERENCE POINT (or standard reference material calibration) ACEADD – THE MEASURING PROCEDURE 28th October Page 7 7

ACEADD – THE MEASURING PROCEDURE 40% 60% Vasari House, Florence 9 - DATA ANALYSES (different analyses available) The ACEADD provides the restaurateur artists with objective data, supporting the following actions: DIAGNOSIS of the degree of deterioration of mural paintings; EVALUATION OF CONSOLIDATION WORKS based on purposely defined criteria; MONITORING of detachments by means of periodic exams. ACEADD – THE MEASURING PROCEDURE 28th October

ACEADD INDUSTRIAL PROTOTYPE CONSERVATION ENTERPRISE & ORGANIZATION ENGINEERING & DISTRIBUTION DIAGNOSTICS SERVICES ENTERPRISE CULTURAL HERITAGE MANAGEMENT ORGANIZATION INSTITUTES & EDUCATION ORGANIZATION Scientific Research Industrial Research Engineering (prototypes) Transfer to Market RESEARCH ORGANIZATIONS PROCESS OF TECHNOLOGICAL TRANSFER TRYING TO ACCESS INDUSTRIAL RESEARCH TRYING TO COOPERATE WITH END USER & ENGENEERING ENTERPRISE ACEADD INDUSTRIAL PROTOTYPE TT ACTIONS ACEADD – RESEARCH & DEVELOPMENT PLAN 28th October Page 9 9

METHODOLOGICAL AND TECHNOLOGICAL ADVANCEMENTS ADVANCED SOLUTIONS FOR MINIMUM SIZE DEVICE ADVANCED SOLUTIONS FOR DATA STORAGE AND DATA TRANSFER (WIRELESS TECHNOLOGIES) FOR ENERGY GENERATION AND ENERGY HARVESTING NON LINEAR ACOUSTIC SOURCE DIRECTIVE SOUND SOURCE STANDARDIZATION OF THE METHODOLOGY AND DEVICE CALIBRATION MODELLING OF REAL DETACHMENTS RESPONSE OF CONSOLIDANTS 80% 60% 30% (xi, yi, hi, ti, Hi(w), di, … , imgi, Ti, Tamb, RH%) (xi, yi) INNOVATIVE SOLUTIONS FOR ALTERNATIVE CONFIGURATION ACEADD – RESEARCH & DEVELOPMENT PLAN 28th October Page 10 10