Evaluation of glass samples for forensic purposes — An application of likelihood ratios and an information-theoretical approach

This article presents an experimental study about the influence of the selection of an adequate database for evidence evaluation using chemical profiles. Evidence evaluation in the forensic sense can be seen as the comparison of two glass objects, one of known origin, denoted as control glass, and typically would be from the scene of a crime, and the other one of unknown origin, termed recovered glass, which might be found in association with a suspect. The aim is to obtain some estimate of the weight of evidence for the degree of support to any of the hypothesis in the case, typically these might be that the control and recovered glass come from the same source (θ_p), and control and recovered glass come from different sources (θ_d). A likelihood ratio is considered a suitable measure of the evidential weight for the competing propositions. The observations are of the elemental composition of glass, measured using a Scanning Electron Microscopy, coupled with an Energy Dispersive X-ray spectrometer technique. A number of glass objects have been analyzed and their chemical profiles form a database which represents several sources of variation. In this paper questions surrounding the choice of observations to make are addressed empirically by assessing the impact of building each model using a database different from the one using for comparison. The performance of each evidence evaluation method is assessed by classical methods such as Tippett plots, or more recent information-theoretical approaches such as empirical cross-entropy (ECE) plots.The results show that several of the compositional elements are very robust to the selection of the background database, namely; calcium, silicon and sodium observed in their oxide forms. We also show that the likelihood ratio computed with the combination of these variables show a remarkable discriminating power, and good calibration, allowing them to be employed for the calculation of the strength of evidence in forensic case work.     

Bioactive Titanium Surfaces Enriched with Silver Nanoparticles Through an In Situ Reduction: Looking for a Balance Between Cytocompatibility and Antibacterial Activity

This research aims toward an antibacterial and osteoconductive Ti₆Al₄V surface by chemical etching–oxidation treatment and in situ reduction of silver nanoparticles. Starting from a previously developed process, already proved to enhance the osteoinductive ability of titanium, different parameters are changed to tailor the amount of silver and its distribution across the surface oxide layer thickness. The samples are characterized by scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, release of silver, biofilm formation (Staphylococcus aureus), and cytocompatibility toward human osteoblasts progenitor cells. The total amount of silver in the surface oxide layer depends only on the concentration of the silver precursor. The time of the addition of the silver precursor, during the oxidation treatment, affects the oxide layer thickness, dimension, and distribution of the nanoparticles across the surface oxide: they are larger and accumulate on the outermost layer, if the addition occurs early. The maximum ion release occurs after 24 h and lasts up to 14 days; the later addition of silver precursors leads to sustaining the silver release for a longer time. The samples prepared with the higher concentration of the silver precursor are bactericide, but highly cytotoxic, whereas the other ones are bacteriostatic and moderately cytotoxic.     

A variable-size local domain approach for increased design confidence in simulation-based optimization

Simulation-based design optimization utilizes computational models that rely on assumptions and approximations. There is a need therefore, to ensure that the obtained designs will exhibit the desired behavior as anticipated given the model predictions. The common approach to accomplish that is to validate the utilized computational models prior to the design optimization process. However, this is practically an impossible task especially for design problems with high-dimensional design and parameter spaces. We have recently proposed a different approach for maximizing confidence in the designs generated during a sequential simulation-based optimization process based on calibrating the computational models when necessary and within local subdomains of the design space. In that work, the size of the local domains was held fixed and not linked to uncertainty, and the confidence in designs was quantified using Bayesian hypothesis testing. In this article, we present an improved methodology. Specifically, we use a statistical methodology to account for uncertainty and to determine the size of the local domains at each stage of the sequential design optimization process using parametric bootstrapping that involves maximum likelihood estimators of model parameters. The sequential process continues until the local domain does not change from stage to stage during the design optimization process, ensuring convergence to an optimal design. The proposed methodology is illustrated with the design of a thermal insulator using one-dimensional, linear heat conduction in a solid slab with heat flux boundary conditions.     

An integrated model for the transshipment yard scheduling problem

A hub-and-spoke railway system is an efficient way of handling freight transport by land. A modern rail–rail train yard consists of huge gantry cranes that move the containers between the trains. In this context, we consider a rail–rail transshipment yard scheduling problem (TYSP) where the containers arrive to the hub and need to be placed on a train that will deliver them to their destination. In the literature, the problem is decomposed hierarchically into five subproblems, which are solved separately. First, the trains have to be grouped into bundles in which they visit the yard. Next, the trains have to be assigned to tracks within these bundles, namely parking positions. Then the final positions for the containers on trains have to be determined. Next, the container moves that need to be performed are assigned to the cranes. Finally, these moves have to be sequenced for each crane for processing. In this paper, an integrated MILP model is proposed, which aims to solve the TYSP as a single optimization problem. The proposed formulation also enables us to define more robust and complex objective functions that include key characteristics from each of the above-mentioned subproblems. The strength of our proposed formulation is demonstrated via computational experiments using the data from the literature. Indeed, the results show that the TYSP can be solved without the use of decomposition techniques and more insight can be obtained from the same input data used to solve particular single decomposed subproblems.     

Algebraic Constructions: A Simple Framework for Complex Dependencies and Parameterisation

We propose a simple framework of algebraic constructions for software specification, modular design and development. Algebraic constructions generalise (parameterised) modules by allowing on one hand a rather arbitrary collection of elements to form the parameter and on the other hand dependencies between the module elements to be spelled out explicitly. Algebraic constructions are specified in a very natural way by means of ordinary algebraic specifications. They are combined using a sum operation which captures as special cases various operations on (parameterised) modules offered by standard specification and development frameworks. We show the expected composability result for the sum of algebraic constructions and of their specifications.     

The influence of zinc ions discharged in a non-aqueous cell on a copper catalyst on the rate of cyclohexanol dehydrogenation reaction

Results of studies on the influence of a copper catalyst modification with zinc ions on the activity in the reaction of cyclohexanol dehydrogenation are presented. The modification has been performed by electrochemical discharging-insertion of zinc ions on a copper electrode in a non-aqueous cell. It has been demonstrated that the catalyst activity depends on the amount of discharged zinc ions as well as on the nature and concentration of the electrolyte. In the case of zinc ions discharged from a solution of ZnCl₂ in propylene carbonate, the yield of cyclohexanone increased up to five times and using Zn(BF₄)₂ in dimethylformamide almost twenty times. The activity of the system in the competing reaction of dehydration was low, hence the selectivity in the dehydrogenation reaction was high.     

Modeling computational limitations in H-Phy and Overlay-NoC architectures

High performance computing demands constant growth in computational power and services that can be offered by modern supercomputers. It requires technological and designing advances in the multiprocessor internal structures as well as novel computing models considering the very high computing demands. One of the increasingly important requirements of computing platforms is a functionality that allows efficient managing computational resources, i.e., monitor them, restrict an access to some part of the resources, account for computational service, or ensure reliability and quality of service when some resources are broken or disabled. In this paper, we present a new model describing computational limitations for processing tasks on multiprocessor systems. The model is implemented in Hardware-Physical (H-Phy) and Overlay-Network-on-Chip (Overlay-NoC) architectures. Both architectures and the model are described and analyzed. Experimentation system is also presented, together with simulation assumptions, results of research and their study. The paper provides complete models of H-Phy and Overlay-NoC structures with an ability to restrict processing resources.     

Studies on the mechanical properties of steel–TiB2 composites obtained by high pressure sintering

The currently used composites produced by classical sintering methods are characterised by numerous limitations due to the difficulties in combining different materials with extreme properties. One of the ways to overcome these limitations is in the use of modern sintering methods, including the high pressure-high temperature process. This study describes the composite materials based on 316L austenitic steel reinforced with titanium diboride and examines the effect of sintering conditions on the mechanical properties and microstructure of sintered composites. It has been found that the key parameter in the manufacture of composites with optimal properties is the sintering time and temperature, while martensitic transformation taking place in the composite matrix can be controlled by the properly selected pressure applied during the sintering process.     

Physicochemical and electrochemical properties of the carbon materials containing nitrogen and cobalt derived from acetonitrile and Co–Al layered double hydroxides

Two sets of the carbon materials containing nitrogen and cobalt were prepared by simultaneous carbonization of CH₃CN and decomposition of Co–Al layered double hydroxides (LDHs) (of Co/Al atomic ratios equal to 2 or 3) at 600, 700 and 800 °C followed by treatment with HCl. The physicochemical features of the samples were characterized by means of XRD, TG, EA, XPS, XRF, FT-IR, SEM, Raman spectroscopy and nitrogen sorption. All of the composites were active in oxygen reduction reaction (ORR) in alkaline medium. Their ORR behaviour was determined by the contribution of structural defects and N-doping in graphitic lattice. The beneficial effect of metallic cobalt encapsulated inside the N-CNTs on the ORR performance was also taken into consideration. The studies showed that the likelihood of the existence of Co–N–C species and their participation in ORR seemed to be suppressed by the formation of CoAl₂O₄. The samples prepared at 600 and 700 °C appeared to be more active in ORR than that obtained at 800 °C. The number of electrons involved in ORR (2.89, 2.82 and 2.77) decreased with increasing synthesis temperature for the samples prepared with LDHs of Co/Al?=?2 as a consequence of lowering concentration of nitrogen (3.2, 2.4 and 1.5 wt%), in particular diminishing contribution of pyridinic nitrogen, and decreasing exposure of graphitic edges (I_D1/I_G?~?2.6, 2.0 and 1.0). The ORR performance of the samples prepared with LDHs of Co/Al?=?3 is comparable to that of the corresponding samples prepared with LDHs of Co/Al?=?2.