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[en] The aim of this essay is to address some of the aspects of the Bridge alternative and to examine the conclusions reached back in 1995 over the feasibility of such a solution. Although having been left aside for decades, the Bridge Solution of the Strait of Gibraltar Crossing Project has been brought back to life as an available alternative to close the gap between the two continents, being the reason to have recently detected some impediment down into the lower layers of the site laying grounds. All of which has revealed further geotechnical issues to tackle. Given the current level of development the Tunnel solution has reached, the 20-year-old Bridge solution needs to be fully updated in order to catch up with the former: As well as taking into consideration the new trends present in the state of the art on design of structures, the Bridge solution would also entail updating construction procedures if it is to incorporate all the potentialities offered by: (1) related tools (2) machinery, and (3), many new ideas which, coming from distinct industrial sectors others than the public works, have worked their way through the construction field. Furthermore, it would be necessary to bear in mind the ceaseless development materials science is going through, which involves constant increases in both levels of resilience and number of characteristics such materials present. (Author)
[en] The mean dimensions of multichain polymer systems are predicted to follow a scaling relation with scaling variable X = l/sup d/ν-1 rho, where l is the number of statistical segments on the chain, rho is the segment density, d is the dimension, and ν is the critical exponent for the mean dimensions of an isolated polymer chain. The scaling laws are < R2>roughly-equalA(X) l/sup 2nu/ for l→ infinity with X bounded, and < R2>roughly-equalB(rho) l for l→ infinity with X → infinity. Moreover, the critical amplitudes behave as A(X)approx.X/sup()( -2nu-1/d/ν-1) as X → infinity and B(rho)approx.rho/sup()( -2nu-1/d/ν-1) as rho → 0. Simulations of both continuum and lattice systems are reanalyzed and found to be consistent with these scaling relations. Previous naive use of short-chain data has led to misleading results
[en] This paper introduces a novel nano-positioning actuator with large displacement and driving force, termed a flexure-based electromagnetic linear actuator (FELA). It mainly comprises an electromagnetic driving scheme and flexure-supporting bearings that provide infinite positioning resolution and highly repeatable motion. In this work, analytical modeling of the proposed electromagnetic scheme and flexure mechanism is presented. Solutions obtained from each model are evaluated by the experimental studies conducted on a FELA prototype. This prototype achieves a stroke of 4 mm with a positioning accuracy of ± 10 nm. With direct force control, it generates various force profiles with a force-current ratio of 60 N A-1 and an accuracy of ± 0.3 N. Such capabilities make FELA a promising solution for realizing ultra-high precision layer-over-layer fabrication in the nano-imprinting process
[en] Samples of (TIGaSe2)1-x(TIInSe2)x solid solutions are synthesized. The frequency dependences (2*10''1-10''6 Hz) of components of the total complex impedance are studied by the impedance spectroscopy technique and relaxation processes are investigated depending on the composition of the (TIGaSe2)1-x(TIInSe2)x solid solution in the solubility region (x=0-0.3). Corresponding diagrams on the (Z-Z') complex plane are analyzed using the equivalent substitution circuit method. An anomaly in the temperature dependence of the electrical conductivity, which manifests itself in an abrupt increase in the conductivity, is found for the studied (TIGaSe2)1-x (TIInSe2)x solid solution at 300K. This peculiarity is associated with the phase transition into the superionic state after 0.25 MGy gamma irradiation.
[en] This work is concerned to study the sintering rate and mass transport mechanism in ceramic engobes. Specimens of engobes were prepared from a determined formulation by slip casting. Sintering was carried in two steps: (i) at constant heating rate of 7.5 degree centigrade/min and (ii) with an isothermal treatment, during 120 min. According to the dilatometric curves obtained with the engobe sintering during isothermal treatment, the dominant sintering mechanism and the rate of reactions, between the 775 and 975 degree centigrade, were determined. The results showed that between 775 and 800 degree centigrade, the sintering rate can be described by ln[d(ΔL/L0)/dt] = -5.64 + 1.77.E10-3T. At higher temperatures, from 850 to 975 degree centigrade, this rate can be expressed by ln[d(ΔL/L0)/ dt] = -30.73 + 3.E10-2T. The dominant transport mass mechanisms were the grain rearrangement, solution-precipitation and grain boundaries reaction. (Author)
[en] Highlights: • Refinement of primary Al3Fe phase liquidly quenched from different temperature melt was estimated quantitatively. • Fe solution in primary phases, eutectic microstructures and Al matrix were carried out. • Increased thermoelectric power of melt reveals the destruction of Al-Fe clusters caused by TEMF.
[en] The paper shows two possibilities obtain first systems of solid phase in the case of growing single-crystals from solutions. These systems, obtained from a supersaturated solution or by a preferential cutting from a single-crystal previously grown, are thermodynamically stable and were used as seeds for further growing under controlled conditions. The paper also mentioned the method used for the growing Kdp single-crystals from solution, the slow cooling method, using seeds obtained by the help of the two methods previously mentioned. In addition, the paper shows two Kdp single-crystals grown from the liquid phase from the two types of seeds
[en] With the recent advances in nanoscale science and engineering, materials containing reinforcement with superior mechanical properties can be found in many advanced products. The accurate prediction of the mechanical properties of this class of composite materials is important to ensure the reliability of the products. Characterization methods based contact probe such as nano-indentation and scratch tests have been developed in recent years to measure the mechanical properties of the new class of nanomaterials. This paper presents a constitutive modeling framework for predicting the mechanical properties of nanoparticle reinforced composite materials. The formulation directly considers the effects of inter-nanoparticle interaction and performs a statistical averaging to the solution of the problem of two-nanoparticle interaction. Final constitutive equations are obtained in analytical closed form with no additional material parameters. The predictions from the proposed constitutive model are compared with experimental measurement from nano-indentation tests. This constitutive model for nanoparticle reinforced composites can be used to determine the volume concentration of the reinforcing nanoparticles in nano-indentation test
[en] Kesterite solid solution of Cu2ZnSn(S,Se)4 have been synthesized by hot-injection and solvothermal methods. The procedure effectiveness that affect to the physical and chemical properties of the final material have been analyzed. The influence of different raw materials and solvents has been investigated in order to improve the preparation procedure. The materials have been characterized structurally and morphologically. (Author)