Physico-chemical characterization of crystalline phases in fly ashes

Fuel oil combustion in power plants, domestic heating systems and diesel engines, causes the emission in the environment of particles with a typical structure and composition: the cenospheres.These particles are produced during the microdrop fuel oil combustion, when air and fuel are injected into the combustion chamber; they have a spheroidal morphology and a spongy structure.Cenospheres are constituted by an amorphous component rich in C, S, Si, Fe and Al; phases composed by microcrystals of sulphates, oxides and pure metallic elements or their alloys, are frequently present in the cenospheres.These crystalline phases are important from environmental and toxicological points of view both because they are composed of heavy metals, and because they can play an important role in heterogeneous catalysis.We started to study these crystalline phases by analytical electron microscopy techniques and electron energy loss spectrometry to define and characterise their structure and composition.     

Conformational analysis of unsaturated molecules: 1,4-cis-dichlorobutene-2

Infrared and Raman spectra have been obtained for 1,4 cis-dibromobutene-2 in the liquid, amorphous and crystalline phases. Normal coordinate calculations have been performed for several model conformations. These data show the SCS and SCS' conformations as the more stable isomers. The two isomers are seen to be of nearly equal energies on the basis of empirical nonbonded-atom calculations,In the crystalline state only one isomer (probably SCS) is found.     

Urban crematoria pollution related to the management of the deceased

The paper gives an overview of data emission from crematoria sited in different regions of Italy that use the same type of machine and examines the requirements that currently used coffins and coffins made of alternative materials must meet under the Decree No. 285/90 (Articles 30–31, 75–77, concerning the mechanical resistance of coffins; Article 8 concerning the observation period before burying the deceased), under the laws No. 644/1975 and No. 578/93 and the Decree No. 582/94 concerning the observation period aimed at confirming the occurred death.As a matter of fact, every step of the management of a corpse brings about all sorts of emissions (liquid, gaseous, wastes) and entails the use of materials and devices that are not always compatible with the current environmental needs. For instance, some materials for the construction of coffins that are suitable for their intrinsic aim may not be so for environmental purposes (biodegradation, recycling, recovery, etc), i.e., they are not easy to treat or they release certain substances upon cremation. Adverse circumstances may lead to the flowing back of gases or liquids generated by the onset of the decomposition process, thus whatever the type of final disposal of the deceased, coffins need to be strong enough to face the various kinds of impacts they meet upon handling, temporary storage, etc. On the basis of mechanical tests on prototypes of coffins made of different materials, the design and construction of a coffin need to be made on the basis of the impact may derive from the onset decomposition process after a minimum period of 24 h after the confirmed death. The results obtained on emissions from crematoria, representing an example of the machines currently in use in Italy, show a wide variation in the content of the pollutants investigated: metals, total particulate matter, organic micropollutants such as dioxin (PCDDs) and furans (PCDFs).     

Headspace gas chromatographic determination of ethylene oxide in air

Summary A simple and accurate headspace-GC method is described to determine the amount of ethylene oxide which has been collected from air using adsorption tubes containing activated charcoal and a relatively safe desorbing agent (N,N-dimethyl acetamide). The detection limit is 40μg/m³.     

CP decomposition for tensors via alternating least squares with QR decomposition

The CP tensor decomposition is used in applications such as machine learning and signal processing to discover latent low-rank structure in multidimensional data. Computing a CP decomposition via an alternating least squares (ALS) method reduces the problem to several linear least squares problems. The standard way to solve these linear least squares subproblems is to use the normal equations, which inherit special tensor structure that can be exploited for computational efficiency. However, the normal equations are sensitive to numerical ill-conditioning, which can compromise the results of the decomposition. In this paper, we develop versions of the CP-ALS algorithm using the QR decomposition and the singular value decomposition, which are more numerically stable than the normal equations, to solve the linear least squares problems. Our algorithms utilize the tensor structure of the CP-ALS subproblems efficiently, have the same complexity as the standard CP-ALS algorithm when the input is dense and the rank is small, and are shown via examples to produce more stable results when ill-conditioning is present. Our MATLAB implementation achieves the same running time as the standard algorithm for small ranks, and we show that the new methods can obtain lower approximation error.     

Shape measurement by a multi-view methodology based on the remote tracking of a 3D optical scanner

Full field optical techniques can be reliably used for 3D measurements of complex shapes by multi-view processes, which require the computation of transformation parameters relating different views into a common reference system. Although, several multi-view approaches have been proposed, the alignment process is still the crucial step of a shape reconstruction.In this paper, a methodology to automatically align 3D views has been developed by integrating a stereo vision system and a full field optical scanner. In particular, the stereo vision system is used to remotely track the optical scanner within a working volume. The tracking system uses stereo images to detect the 3D coordinates of retro-reflective infrared markers rigidly connected to the scanner. Stereo correspondences are established by a robust methodology based on combining the epipolar geometry with an image spatial transformation constraint.The proposed methodology has been validated by experimental tests regarding both the evaluation of the measurement accuracy and the 3D reconstruction of an industrial shape.