A survey of convergence results on particle filtering methods forpractitioners

Optimal filtering problems are ubiquitous in signal processing and related fields. Except for a restricted class of models, the optimal filter does not admit a closed-form expression. Particle filtering methods are a set of flexible and powerful sequential Monte Carlo methods designed to. solve the optimal filtering problem numerically. The posterior distribution of the state is approximated by a large set of Dirac-delta masses (samples/particles) that evolve randomly in time according to the dynamics of the model and the observations. The particles are interacting; thus, classical limit theorems relying on statistically independent samples do not apply. In this paper, our aim is to present a survey of convergence results on this class of methods to make them accessible to practitioners     

In vitro assessment and monitoring of the implant titanium materials – physiological environment interactions

Long‐term monitoring (for 8000 exposure hours) of titanium and its implant alloys (Ti‐5Al‐4V, Ti‐6Al‐4Fe) interactions with Ringer's solutions of different pH‐values (2.5, 4.35, 6.98), simulating various conditions that can appear at the contact between implant and tissues was carried out in this paper. All data were statistics treated using Medcalc program. In vitro electrochemical behaviour of titanium and its alloys reveals their self‐passivation in Ringer's solutions. Monitoring of the open circuit potentials with time and pH have shown that the passive films on the implant materials studied were very stable for all tested periods. Interactions due to the non‐uniformity of the physiological electrolyte pH can not produce any form of local corrosion. The tested materials present low corrosion rates which attest their very good stability for 8000 exposure hours in simulated biological environment. Surface topography characterisation using atomic force microscopy (AFM) data, correlated with the electrochemical parameters, were arguments for the stability of the samples in studied bioliquids.     

Extraction method for source series resistance and transverse field mobility reduction coefficient using the MOSFET saturation region

A new extraction method for source series resistance and mobility reduction coefficient with transverse field, based on the MOSFET transconductance modeling in the saturation region, is reported. The simple associated transconductance model also appears to be extremely useful for optimal parameter extraction. The proposed method is validated on partially depleted SIMOX MOSFETs.     

On the limiting factors of the critical current density in high-Tc superconducting ceramics

The temperature dependence of the critical current density at high temperatures and in weak applied magnetic field for YBa₂Cu₃O_7–y ceramic samples with a pronounced granular character is analyzed. The experimental results can be explained in terms of thermally activated motion of the intergrain Josephson vortices at grain boundaries, which may be an indication that the actual limiting factor for the critical current density in ceramic samples results from a weak pinning force density for the intergrain vortices rather than from the weak-link quenching.     

Mega-voltage versus kilo-voltage cone beam CT used in image guided radiation therapy: comparative study of microdosimetric properties

Mega-voltage computed tomography (MVCT) and kilo-voltage cone beam CT (CBCT) are routinely used in image-guided radiation therapy. In current practice, doses from MVCT and CBCT are reported with no correction for radiation quality. In this study, we compared microdosimetric properties as well as doses for MVCT and CBCT. Monte Carlo simulation codes BEAMnrc and DOSXYZnrc were used to simulate a Varian CBCT 125 kVp photon beam and primary electron spectra for CT sets of two patients. The revised Oak Ridge Electron transport Code (NOREC) was used to simulate electron tracks in liquid water. C++ code was developed to compute lineal energy in a sphere of 1 μm diameter. Dose-mean lineal energy-based quality factors were calculated for critical organs in-field. The estimated quality factor for CBCT is up to a factor of 1.3 times that of MV beams.     

Effects of LP-MOCVD prepared TiO2 thin films on the in vitro behavior of gingival fibroblasts

We report on the in vitro response of human gingival fibroblasts (HGF-1 cell line) to various thin films of titanium dioxide (TiO₂) deposited on titanium (Ti) substrates by low pressure metal-organic chemical vapor deposition (LP-MOCVD). The aim was to study the influence of film structural parameters on the cell behavior comparatively with a native-oxide covered titanium specimen, this objective being topical and interesting for materials applications in implantology. HGF-1 cells were cultured on three LP-MOCVD prepared thin films of TiO₂ differentiated by their thickness, roughness, transversal morphology, allotropic composition and wettability, and on a native-oxide covered Ti substrate. Besides traditional tests of cell viability and morphology, the biocompatibility of these materials was evaluated by fibronectin immunostaining, assessment of cell proliferation status and the zymographic evaluation of gelatinolytic activities specific to matrix metalloproteinases secreted by cells grown in contact with studied specimens. The analyzed surfaces proved to influence fibronectin fibril assembly, cell proliferation and capacity to degrade extracellular matrix without considerably affecting cell viability and morphology. The MOCVD of TiO₂ proved effective in positively modifying titanium surface for medical applications. Surface properties playing a crucial role for cell behavior were the wettability and, secondarily, the roughness, HGF-1 cells preferring a moderately rough and wettable TiO₂ coating.     

Nano-scale metallic iron for the treatment of solutions containing multiple inorganic contaminants

Although contaminant removal from water using zero-valent iron nanoparticles (INP) has been investigated for a wide array of chemical pollutants, the majority of studies to date have only examined the reaction of INP in simple single-contaminant systems. Such systems fail to reproduce the complexity of environmental waters and consequently fail as environmental analogues due to numerous competitive reactions not being considered. Consequently there is a high demand for multi-elemental and site-specific studies to advance the design of INP treatment infrastructure. Here INP are investigated using batch reactor systems over a range of pH for the treatment of water containing multi-element contaminants specifically U, Cu, Cr and Mo, selected to provide site-specific analogues for leachants collected from the Li?ava mine, near Oravi?a in South West Romania. Concurrently, a U-only solution was also analysed as a single-system for comparison.     

高度多孔纳米结构纤维素纤维的溶液纺丝工艺

由纤维素生产纤维的常规生产方法,迄今已生产了具有致密微结构和极大长径比的材料。在此介绍的表面多孔的纤维是一种新型纤维状材料,为科学家和工程师提供了许多挑战和机会。由于纳米结构纤维的特性,它在工业产品,例如从过滤到类似药物释放载体的特殊产品的许多用途中具有很大潜力。通过采用溶胶凝胶方法,首次制成了表面多孔的纳米结构纤维素纤维。     

Synthesis and characterization of some 2,4′-dibenzyldiisocyanate ionic polymers

Cationic polyurethanes were synthesized by a two step Menschutkin reaction. A prepolymer with tertiary dimethylamino end groups and a dihalide (1,3-dimethyl-4,6-di(chloromethyl) benzene) were used in the first step, and 1,8-diaza bicyclooctane in the second step. The polymers from flexible and transparent films and their solutions give ionomer dispersions by adding of acetone. The viscometric behaviour of diluted solutions was studied in solvents with different dielectrical constants.