Noise–Power Optimization of Incremental Data Converters

Incremental data converters (IDCs) are useful in instrumentation and measurement applications, where low-frequency analog signals need to be converted into digital form with high accuracy and low power dissipation. They are particularly well suited for applications where a single analog-digital converter is multiplexed between many channels. This paper proposes an exact design methodology for IDCs, which optimizes the signal-to-noise ratio of the converter under practical design constraints. The process also allows the designer to apportion the noise budget in an arbitrary manner between thermal and quantization noise. The design process is illustrated by an example which describes the optimization of a third-order multiplexed IDC.     

Closed-form pose estimation from metric rectification of coplanar points

A new analytic method for estimating the pose of a calibrated camera from a single view of a planar target with a known geometry is presented. A set of fiducial points is extracted from an image of this target and metrically rectified through a 2D homography. The author's contribution consists in deriving from the coefficients of this transformation the analytic expressions of the 3D rigid motion parameters defining the pose of the camera. Experiments with synthetic data show the effectiveness of the proposed method against another gold-standard method for pose estimation and its robustness against perturbations of the fiducial points. These features make the algorithm a perfect candidate for all those applications where pose estimation has to be performed reliably and in real time.     

A new prefabricated external thermal insulation composite board with ceramic finishing for buildings retrofitting

Given the high energy consumption connected to old buildings and their large environmental impact, there is a strong need for effective solutions for the building envelope retrofitting. Among these solutions, external thermal insulation composite systems (ETICS) have found large application in recent decades. In this paper a new kind of large-size thermal insulation composite boards, prefabricated using porcelain stoneware slab finishing, was developed. Different thermal insulating materials and adhesives, with and without glass fibre mesh, were tested by both current methodologies and purposely designed tests, in order to assess their physical–mechanical properties and durability performance, finally selecting the most suitable materials for the composite board. The strong points of this composite board are mainly: (i) its short placing time and improved execution quality, due to prefabrication; (ii) its high aesthetical value; (iii) its high durability, as the finishing layer is mostly insensible to weathering. The results highlight the good performances of the prefabricated composite board developed in this study (generally higher than current ETICS). The testing procedure followed in this study is also meant to give a contribution to the establishment of methodologies for the selection and durability assessment of materials for the building envelope retrofitting.     

Estimation of two-dimensional affine transformations through polar curve matching and its application to image mosaicking and remote-sensing data registration.

This paper presents a new and effective method for estimating two-dimensional affine transformations and its application to image registration. The method is based on matching polar curves obtained from the radial projections of the image energies, defined as the squared magnitudes of their Fourier transforms. Such matching is formulated as a simple minimization problem whose optimal solution is found with the Levenberg-Marquardt algorithm. The analysis of affine transformations in the frequency domain exploits the well-known property whereby the translational displacement in this domain can be factored out and separately estimated through phase correlation after the four remaining degrees of freedom of the affine warping have been determined. Another important contribution of this paper, emphasized through one example of image mosaicking and one example of remote sensing image registration, consists in showing that affine motion can be accurately estimated by applying our algorithm to the shapes of macrofeatures extracted from the images to register. The excellent performance of the algorithm is also shown through a synthetic example of motion estimation and its comparison with another standard registration technique.     

A frequency domain technique for range data registration

This work introduces an original method for registering pairs of 3D views consisting of range data sets which operates in the frequency domain. The Fourier transform allows the decoupling of the estimate of the rotation parameters from the estimate of the translation parameters, our algorithm exploits this well-known property by suggesting a three-step procedure. The rotation parameters are estimated by the first two steps through convenient representations and projections of the Fourier transforms' magnitudes and the translational displacement is recovered by the third step by means of a standard phase correlation technique after compensating one of the two views for rotation. The performance of the algorithm, which is well-suited for unsupervised registration, is clearly assessed through extensive testing with several objects and shows that good and robust estimates of 3D rigid motion are achievable. Our algorithm can be used as a prealignment tool for more accurate space-domain registration techniques, like the ICP algorithm.     

A noise-robust frequency domain technique for estimating planarroto-translations

This work presents a new method for estimating planar roto-translations that operates in the frequency domain and as such, is not based on features. Since the proposed technique uses all the image information, it is very robust against noise, it can be very accurate; estimation errors on the rotational angle varies from a few hundredths to a few tenths of a degree, depending on the noise level. Experimental evidence of this performance is presented, and the mathematical reasons behind these characteristics are explained in depth. Another remarkable feature of the algorithm consists in that it works in Cartesian coordinates, bypassing the need to transform from the Cartesian to the polar domain, which, typically, is a numerically delicate and computationally onerous task. The proposed technique can become an effective tool for unsupervised estimation of roto-translations by means of implementations based on FFT algorithms     

Use of microwave dielectric loss for characterisation of natural rubber/carbon black composites

Summary Microwave dielectric loss spectroscopy (MDS) has shown remarkable potential as a tool for the observation of changes in elastomer network structure within the interphase region of natural rubber/ carbon black composites. During crosslinking (non elemental sulphur system) the dielectric loss progressively increased. However, during ageing at high temperature the dielectric loss decreased. Parallel studies on the unfilled matrix yielded no such variation in dielectric loss. It was therefore concluded that the changes in microwave responses were related to the development of the interphase during curing and its subsequent destruction during ageing. The microwave response was related to the composite mechanical properties as a function of ageing time. The effect of stabiliser was also investigated. Received: 13 September 1999/Revised version: 7 February 2000/Accepted: 10 February 2000     

The oral status in mentally retarded institutionalized patients

BACKGROUND AND METHODS: An epidemiological survey of dental and periodontal health status was conducted in a group of 263 institutionalized mentally retarded patients. RESULTS: The periodontal status in the study population was very poor. 66% of the subjects presented with a probing depth more than 3.5 mm (PSR = 3 or 4), 29% showed the presence of bleeding or calculus (PSR = 1 or 2) and only 5% showed a normal periodontal status (PSR = 0). No statistical relationship was found between periodontal status and age, sex, type or duration of psychiatric therapy. Concerning the dental status a total of 59 (26%) subjects was totally edentulous. A significant increase in the prevalence of edentulousness with increasing age was recorded. The incidence of edentulousness was higher among women than among men, while it was not significantly influenced by the type of psychiatric pathology, type or duration of psychiatric therapy. The mean number of remaining teeth in every subject was 12.9 +/- 9; the mean number of sound teeth was 10.8 +/- 8 and the mean number of decayed teeth was 2.1 +/- 3. The number of decayed teeth decreased with increasing age and it was influenced by the type of psychiatric pathology, but not by the type or duration of psychiatric pathology. CONCLUSIONS: Analysis of the results showed a very poor dental but especially periodontal status in mentally retarded subjects as compared to those found in studies performed in normal subjects.     

Biodiesel compatibility with carbon steel and HDPE parts

Compatibility of the new environmentally-friendly alternative of diesel engine fuels, biodiesel, with storage and engine part materials, is still an open issue. In this work, the interaction between three fuels (petroleum diesel and two types of biodiesel — soybean and sunflower) and two materials (carbon steel and high density polyethylene) used in storage and automotive tanks, is analyzed in detail. A wide set of characterization techniques was used to evaluate the changes in both solid and fluid materials, as weight change measurement, optical, scanning electron and atomic force (AFM) microscopies, Raman and FTIR spectroscopies, and differential scanning calorimetry. The AFM technique allowed detecting surface roughness and morphology changes in the metallic material following the trends in the weight losses. In the case of polymeric material, weight gain by fluid absorption occurred, being detected by the spectroscopic techniques. The biodiesel fuels underwent some ageing however this phenomenon did not affect the interaction between the biodiesel fuels and the substrates. The petrodiesel, which did not age, caused more significant degradation of the substrates.