A First-Order Primal-Dual Algorithm for Convex Problems with Applications to Imaging

In this paper we study a first-order primal-dual algorithm for non-smooth convex optimization problems with known saddle-point structure. We prove convergence to a saddle-point with rate O(1/N) in finite dimensions for the complete class of problems. We further show accelerations of the proposed algorithm to yield improved rates on problems with some degree of smoothness. In particular we show that we can achieve O(1/N ²) convergence on problems, where the primal or the dual objective is uniformly convex, and we can show linear convergence, i.e. O(ω ^N ) for some ω∈(0,1), on smooth problems. The wide applicability of the proposed algorithm is demonstrated on several imaging problems such as image denoising, image deconvolution, image inpainting, motion estimation and multi-label image segmentation.     

A hybrid Differential Evolution—Tabu Search algorithm for the solution of Job-Shop Scheduling Problems

The Job-Shop Scheduling Problem (JSSP) has drawn considerable interest during the last decades, mainly because of its combinatorial characteristics, which make it very difficult to solve. The good performances attained by local search procedures, and especially Nowicki and Smutnicki's i-TSAB algorithm, encouraged researchers to combine such local search engines with global methods. Differential Evolution (DE) is an Evolutionary Algorithm that has been found to be particularly efficient for continuous optimization, but which does not usually perform well when applied to permutation problems. We introduce in this paper the idea of hybridizing DE with Tabu Search (TS) in order to solve the JSSP. A competitive neighborhood is included within the TS with the aim of determining if DE is able to replace the re-start features that constitute the main strengths of i-TSAB (i.e., a long-term memory and a path-relinking procedure). The computational experiments reported for more than 100 JSSP instances show that the proposed hybrid DE–TS algorithm is competitive with respect to other state-of-the-art techniques, although, there is still room for improvement if the adequacy between the solution representation modes within DE and TS is properly stressed.     

Hydrogen peroxide in bioelectrochemical systems negatively affects microbial current generation

Journal of Applied Electrochemistry - Hydrogen peroxide produced in the cathode of a bioelectrochemical system (BES) enables on-site disinfection of water using electrons derived from the...     

An Algorithm for Total Variation Minimization and Applications

We propose an algorithm for minimizing the total variation of an image, and provide a proof of convergence. We show applications to image denoising, zooming, and the computation of the mean curvature motion of interfaces.     

Nanocarbon Allotropes—Graphene and Nanocrystalline Diamond—Promote Cell Proliferation

Two profoundly different carbon allotropes – nanocrystalline diamond and graphene – are of considerable interest from the viewpoint of a wide range of biomedical applications including implant coating, drug and gene delivery, cancer therapy, and biosensing. Osteoblast adhesion and proliferation on nanocrystalline diamond and graphene are compared under various conditions such as differences in wettability, topography, and the presence or absence of protein interlayers between cells and the substrate. The materials are characterized in detail by means of scanning electron microscopy, atomic force microscopy, photoelectron spectroscopy, Raman spectroscopy, and contact angle measurements. In vitro experiments have revealed a significantly higher degree of cell proliferation on graphene than on nanocrystalline diamond and a tissue culture polystyrene control material. Proliferation is promoted, in particular, by hydrophobic graphene with a large number of nanoscale wrinkles independent of the presence of a protein interlayer, i.e., substrate fouling is not a problematic issue in this respect. Nanowrinkled hydrophobic graphene, thus, exhibits superior characteristics for those biomedical applications where high cell proliferation is required under differing conditions.     

Effect of temperature on the sorption curves of earthen materials

Unfired earth is a sustainable construction material with low embodied energy, but its development requires a better evaluation of its moisture–thermal buffering abilities and its mechanical behavior. Both of them are known to strongly depend on the amount of water contained in its porous network and its evolution with external conditions (temperature, humidity), which can be assessed through several sorption–desorption curves at different temperature. However, the direct measurement of these curves is particularly time consuming (up to 2 month per curve) and thus, indirect means of their determination appear of main importance for evident time saving and economical reasons. In this context, this paper focuses on the prediction of the evolution of sorption curves with temperature on earth plasters and compacted earth samples. For that purpose, two methods are proposed. The first one is an adaptation of the isosteric method, which gives the variation of relative humidity with temperature at constant water content. The second one, based on the liquid–gas interface equilibrium, gives the variation of water content with temperature at constant relative humidity. These two methods lead to quite consistent and complementary results. It underlines their capability to predict the sorption curves of the tested materials at several temperatures from the sole knowledge of one sorption curve at a given temperature. Finally, these predictions are used to scan the range of temperature variation within which the evolution of water content with temperature at constant humidity could be neglected or should be taken into account.     

Comparative content of some phytochemicals in Spanish apples,peaches and pears

Dietary fibre, total polyphenols and phenolic acids in Spanish apples, peaches and pears were analysed and compared with their total radical‐trapping antioxidative potential (TRAP). There were no significant differences in the content of dietary fibre among the studied fruits. The content of total polyphenols was 2.4 ± 0.4, 2.1 ± 0.3 and 6.9 ± 0.7 g kg^?1 in peeled fruits and 4.7 ± 0.4, 4.5 ± 0.4 and 11.1 ± 1.2 g kg^?1 in their peels for peaches, pears and apples respectively. The contents of dietary fibre, total polyphenols, caffeic, p‐coumaric and ferulic acids and the TRAP values were significantly (P < 0.05) higher in peels than in peeled fruits. The contents of all studied compounds and the TRAP values were significantly higher in peeled apples and their peel than in peaches and pears. We observed a strong correlation between the contents of total polyphenols and phenolic acids and the total radical‐trapping antioxidative potential in all three fruits. The relatively high content of dietary fibre, the highest contents of total polyphenols, caffeic, p‐coumaric and ferulic acids and the highest value of TRAP make apples preferable among the studied fruits for dietary prevention of atherosclerosis and other diseases. © 2002 Society of Chemical Industry     

RedOx study of anode-supported solid oxide fuel cell

The common technology for solid oxide fuel cells (SOFC) is based on a cermet (ceramic-metal composite) anode of nickel with yttria stabilized zirconia (YSZ), often used as the supporting structure. One of the main limitations of this technology is the tolerance of the anode towards reduction and oxidation (“RedOx”) cycles.In this study, two techniques are used to quantify the anode expansion after a RedOx cycle of the nickel at different temperatures. The first method considers the anode expansion above the electrolyte fracture limit by measuring the crack width in the electrolyte layer. In the second method, the anode porosity is measured using scanning electron microscopy (SEM) image quantification. The same measurement techniques are used to quantify anode expansion after consecutive RedOx cycles at constant temperature.The quantification technique is then applied to cells tested in real stack conditions. The cell corners can undergo several RedOx cycles depending on stack design and fuel utilization. The study of such zones allows estimating the number of cycles that the anode experienced locally.     

Design of experiment approach applied to reducing and oxidizing tolerance of anode supported solid oxide fuel cell. Part I: Microstructure optimization

The main drawback of Ni/YSZ anode supports for solid oxide fuel cell application is their low tolerance to reducing and oxidizing (RedOx) atmosphere changes, owing to the Ni/NiO volume variation. This work describes a structured approach based on design of experiments for optimizing the microstructure for RedOx stability enhancement. A full factorial hypercube design and the response surface methodology are applied with the variables and their variation range defined as: (1) NiO proportion (40-60 wt% of the ceramic powders), (2) pore-former proportion (0-30 wt% corresponding to 0-64 vol.%), (3) NiO particle size (0.5-8 μm) and (4) 8YSZ particle size (0.6-9 μm).To obtain quadratic response models, 25 different compositions were prepared forming a central composite design. The measured responses are (i) shrinkage during firing, (ii) surface quality, (iii) as-sintered porosity, (iv) electrical conductivity after reduction and (v) expansion after re-oxidation. This approach quantifies the effect of all factors and their interactions. From the quadratic models, optimal compositions for high surface quality, electrical conductivity (>500 S cm⁻¹ at room temperature) and RedOx expansion (<0.2% upon re-oxidation) are defined. Results show that expansion after re-oxidation is directly influenced by the sample porosity whereas, surprisingly, the NiO content, varied between 40 and 60 wt%, does not show any impact on this response.     

Fat content and fatty acids profile of colostrum and milk of primitive Konik horses ( Equus caballus gmelini Ant.) during six months of lactation

The effect of the stage of lactation, the number of foals and age of the mare on changes in the fat content and fatty acid composition of colostrum and milk of primitive Konik horses was investigated. Colostrum and milk samples from 12 lactating mares were collected at the beginning of lactation, on the days 1 and 2 after foaling and then, starting from the first month of lactation, at 4-week intervals up to the sixth month of lactation. Significant differences were observed in fat content as well as the composition of some analysed fatty acids between colostrum and milk of mares of the Konik breed. The number of foalings and the age of mares did not have a statistically significant effect on the fat content in milk and had only a slight effect on the fatty acid composition. Milk produced by mares of the Konik breed is characterized by a considerable content of polyene fatty acids with 18 carbon atoms, a low ratio of n-6 fatty acids to n-3 fatty acids as well as low, highly advantageous values of atherogenic and thrombogenic indices.