Project: Microwave Axial Tomograph for the Health Examination of Wood

Non-destructive evaluation (NDE) of wood samples is needed in many practical situations, where there is the need to examine the internal structure without damaging or altering its integrity. As an example, such need is particularly felt in urban areas where large trees are present. In this case, it is of great importance to have a mean for inspecting the health of the trunks, in order to avoid that an unhealthy tree can collapse under the effect of meteorological events. Moreover, the knowledge of the internal statuses of the trunks can avoid cutting healthy trees. _x000D__x000D_A key important example is represented by the quality inspection of wood slabs used in manufacturing processes. In this case, NDE systems can reduce the uncertainty on the wood internal characteristics, allowing for a better use of the available raw materials On such basis, in the past years there has been a growing interest in developing fast and affordable NDE systems for evaluating the properties (e.g. physical, mechanical, chemical, aesthetic properties) that can provide useful information about the health of the wood sample. In particular, well known approaches, e.g. ultrasonic imaging, X-ray imaging, resistance or capacitance tomography, have been successfully applied. However, all of them present draw-backs that limit their practical application (e.g. X-ray systems are hazardous for personnel while ultrasonic systems need contact operation). _x000D__x000D_In the framework of new and emerging imaging techniques for material characterization, microwave-based systems are playing an ever growing importance in several fields. In fact, microwaves exhibit some potential ad-vantages over previously proposed non-destructive techniques. First of all, since they use low-level non-ionizing radiations, they are safe for personnel and other people standing nearby, thus allowing also a continuous monitoring of the structures. Moreover, since microwave are nowadays used in several other apparatuses (e.g. communication equipment), the needed electronic parts are far less expensive than those of other diagnostic units (e.g. X-ray-based ones). _x000D__x000D_Commercially available microwave NDE systems are usually based on standard transmission/reflection concepts, i.e. a “mean” value of the dielectric properties of the objects are directly related to the fraction of energy transmitted through or reflected by the object. Moreover, radar principles (i.e. correlation between time of flight and distance) are sometimes used to find an estimated of the external shape of the structure. _x000D__x000D_In the proposers' opinion, there is still a great gap between the diagnostic capabilities of such devices and the level they could reach if techniques not limited to reflection/transmission concepts would be adequately developed. In particular, systems based on the tomographic inversion of the electromagnetic field scattered by the objects (properly measured by probes) can directly provide the whole distributions of the dielectric parameters (i.e. the dielectric permittivity, the magnetic permeability, and the electric conductivity) of the sample under test. The maps of these quantities cannot be obtained by using standard diagnostic techniques._x000D_ _x000D_Consequently, the project aims at the development of a microwave tomograph prototype, which can generate 2D images of slices of wood trunks. The system will operate in the microwave frequency range (in particular, frequencies between about 1 GHz and 10 GHz will be firstly considered) and will be made by the following major blocks:_x000D_ ¦ A circular array of antennas, acting for both illuminating and sensing the wood trunk and able to cover the whole circumference of the trunk._x000D_ ¦ A microwave transmitter/receiver, that generates the probing signals and can measure both the amplitude and the phase of the scattered electric field at the probe positions._x000D_ ¦ An electronic module to control the microwave parts and the measurement process. It will also contain a communication processor that will interface to a PC over an Ethernet (LAN) interface._x000D_ ¦ A software module aimed at inverting and processing the measured data, in order to construct the 2D image of a slice of the wood trunk._x000D_ ¦ A Graphical User Interface module, that will give the end user an easy way to interact with before mentioned hardware and software._x000D__x000D_The Consortium for the MATHEW project is composed by:_x000D_• 2 SME: one Italian (FOS) wich operates in ICT and electronics sector and one Swiss (Coletta) which is a Timber Mill and hence a doCO expert of the wood industry;_x000D_• 2 Research Institutes: University of Genova (Italy) which has strong competence in the electromagnetism field (hw and sw), and SUPSI (CH) which has a long track record in projects related to the field of Non-Destructive Material Testing (NDMT), based on microwave sensors_x000D_

Acronym MATHEW (Reference Number: 6946)
Duration 01/02/2013 - 31/01/2016
Project Topic The project aims at the development of a microwave tomograph prototype, which can generate 2D images of slices of wood trunks. The envisioned field of use is in the non-destructive assessment of the degree of health of trees (to prevent the risk of injuries by precarious trees being knocked down by
Network Eurostars
Call Eurostars Cut-Off 7

Project partner

Number Name Role Country
4 FOS Srl (Field Organization System) Coordinator Italy
4 Università degli Studi di Genova Partner Italy
4 Segheria alla Coletta Partner Switzerland
4 Scuola universitaria professionale della Svizzera italiana, Dipartimento tecnologie innovative (DTI) Partner Switzerland