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1.
Auguet C. Martorell F. Moll F. Torra V: 《Journal of Thermal Analysis and Calorimetry》2002,70(1):277-290
The miniaturized calorimetric devices furnish a reduced working flat surface and permits measurements with extremely low-mass
quantities. The experimental sensitivity shows relevant position dependence with x-y surface coordinates and with z-distance. The device identification is realized via a 2-D model based in Fourier general equation.
Using the Marquardt method the experimental flat surface device can be identified and the fitted parameters used to simulate
the behavior of the experimental system. From the model, the effects of several dissipation configurations can be evaluated.
Also, via the RC-analogy, a way to 3-D experimental devices is roughly described.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
C. Auguet J. L. Seguin F. Martorell F. Moll V. Torra J. Lerchner 《Journal of Thermal Analysis and Calorimetry》2006,86(2):521-529
Micro-calorimetric
devices using Si-based sensors are very useful for the study of gas–solid
reactions, in which very low mass of reactants are necessary. But in fact
the consequence of using flat detectors is an increase of the uncertainty
in the measured energy. In this work a calorimetric gas sensor based on Xensor
chip is analysed studying the local x–y
contributions of dissipation to the sensitivity related to the value in the
centre. We study also the effects of the gas-flow on the sensitivity, comparing
the results obtained with two Xensor type chips. Finally we carry out a deeper
analysis of the x–y effects on the
calorimetric detector for dissipations in the reactant shell extremely close
to the detector surface to visualize the link between the power density distribution
and the output signal. 相似文献
3.
C. Auguet A. Isalgué F. C. Lovey F. Martorell V. Torra 《Journal of Thermal Analysis and Calorimetry》2007,88(2):537-548
The behavior of shape memory alloys (SMA) allows their use as a passive
smart material. In particular, the existence of a hysteretic cycle in the
domain of the elementary coordinates strain-stress-temperature (σ, ε, T) suggests its application for damping
in mechanical and/or in civil engineering. We are working in the application
of SMA as dampers for earthquakes in small houses as family homes. For dampers
installed in the inner porticos of the house, the suggested SMA is the CuAlBe
and, eventually, the NiTi. At room temperature the used SMA wires induces
forces situated between 2–3kN/wire. The properties related with the
damping applications for CuAlBe and NiTi, i.e., the SMA creep and the self-heating
will be presented, together with some other minor stress and temperature effects
on NiTi modifying the hysteretic behavior. 相似文献
4.
5.
J. Hanus A. Auguet E. Hildt und B. M. Margosches 《Fresenius' Journal of Analytical Chemistry》1927,72(1-2):69-73
Ohne Zusammenfassung 相似文献
6.
Lacasta AM Cantalapiedra IR Auguet CE Peñaranda A Ramírez-Piscina L 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》1999,59(6):7036-7041
A diffusion-reaction model for the growth of bacterial colonies is presented. The often observed cooperative behavior developed by bacteria which increases their motility in adverse growth conditions is here introduced as a nonlinear diffusion term. The presence of this mechanism depends on a response which can present hysteresis. By changing only the concentrations of agar and initial nutrient, numerical integration of the proposed model reproduces the different patterns shown by Bacillus subtilis OG-01. 相似文献
7.
C. Auguet A. Isalgue F. C. Lovey J. L. Pelegrina S. Ruiz V. Torra 《Journal of Thermal Analysis and Calorimetry》2007,89(2):537-542
The applicability of shape memory alloys (SMA) for dampers in civil engineering requires guaranteed behavior with well controlled
or irrelevant changes after several years of inactivity and/or under the action of daily or seasonal temperature effects.
The long time analysis of the aging temperature effects on a NiTi alloy shows similar behavior to other SMA but with higher
time constants at temperatures near 373 K: 1.9 days at 410 K and near 100 days at 363 K with an activation energy value near
12500 K (RT=104 kJ mol−1). At the present state of the art, the measurements show that the change of transformation temperatures under the action
of the external temperature (or ‘room temperature’ change) is close to 15 K. The direct use of the as furnished material can
suffer relevant changes of working properties in devices under the action of direct sunlight or high room temperature working
conditions. 相似文献
8.
Auguet C. Lerchner J. Marinelli P. Martorell F. Rodriguez de Rivera M. Torra V. Wolf G. 《Journal of Thermal Analysis and Calorimetry》2003,71(3):951-966
The experimental analysis of conventional conduction calorimeters shows excellent reproducibility and relevant systematic
errors in comparison with thermodynamic values established via adiabatic calorimeters. Two examples: a DSC and a liquid flow
device are schematically analyzed. When an increased accuracy will be obtained the positional effects on the experimental
set-up and on the measurement process need to be modelled. From experimental measurements realized on the Xensor liquid nano-calorimeter
representative models can be built. To evaluate the reliability of measurement routines, established from experimental basis,
several different dissipation structures inside the working space can be simulated. Two experimental configurations related
to drop to drop reaction and to continuous mixing are modelled via RC approach. The RC formalism is extended to evaluate the
carried energy effect produced by the continuous inflow/outflow of reactants in the mixing enthalpy chamber.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
C. Auguet A. Isalgue V. Torra F. C. Lovey J. L. Pelegrina 《Journal of Thermal Analysis and Calorimetry》2008,92(1):63-71
Shape memory alloys (SMA) are interesting for applications in damping of civil engineering structures. To achieve the SMA
as a guaranteed material for damping of structures requires a reliability study of the static and dynamic properties adapted
to each type of application. Here we present static (temperature and time effects) and dynamic actions in pseudo-elastic NiTi
SMA. We concern with long time effects of temperature and time mainly in beta phase.
NiTi results are presented, including measurements of electrical resistance as a function of temperature and time, DSC to
−80°C (TA Instruments), non-conventional conduction calorimetry (to 80 K), and several X-ray diffraction spectra at different
temperatures. Diffusion effects are present, and all the measurements show that transformation temperatures change with time
of aging even at moderate temperatures (i.e., near 100°C), depending on time and temperature. It is possible to visualize
the diffusion change in the R phase transformation via classical X-ray characterization. We include some results of pre-stressing
effects applying the stress at different zones of the hysteresis cycle. The experimental analysis shows that coupling between
stress and temperature enhances the changes. For long times (10, 20 years) and direct sunny actions, more deep analysis is
required. Finally, some dynamic effects in cycling affecting the SMA creep are outlined. 相似文献
10.
A. Peñaranda C.E. Auguet L. Ramırez-Piscina 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,25(2):155-165
The simulation of the transition sequence of superheated Type I superconducting granules (SSG) in disordered suspensions when
an external magnetic field is slowly increased from zero has been studied. Simulation takes into account diamagnetic interactions
and the presence of surface defects. Results have been obtained for the transition sequence and surface fields distribution
covering a wide range of densities. These results are compared with previous analytical perturbative theory, which provides
qualitative information on transitions and surface magnetic fields during transitions, but with a range of validity apparently
limited to extremely dilute samples. Simulations taking into account the complete diamagnetic interactions between spheres
appear to be a promising tool in interpreting SSG experiments, in applications such as particle detectors, and in some fundamental
calculations of Solid State Physics.
Received 6 April 2001 and Received in final form 15 October 2001 相似文献