S. Aparicio | CSIC (Consejo Superior de Investigaciones Científicas-Spanish National Research Council) (original) (raw)
Papers by S. Aparicio
Sensors, 2019
In this paper, a magnetic microwire-based sensor array embedded under the pavement is proposed as... more In this paper, a magnetic microwire-based sensor array embedded under the pavement is proposed as a weighing system at customs ports of entry. This sensor is made of a cementitious material suitable for embedding within the core of concrete structures prior to curing. The objective of this research is to verify the feasibility of stress monitoring for concrete materials using an array of cement-based stress/strain sensors that have been developed using the magnetic sensing property of an embedded microwire in a cement-based composite. Test results for microwire-based sensors and gauge sensors are compared. The strain sensitivity and their linearity are investigated through experimental testing under compressive loadings. Sensors made of these materials can be designed to satisfy specific needs and reduce costs in the production of sensor aggregates with improved coupling performance, thus avoiding any disturbance to the stress state.
Monthly Notices of the Royal Astronomical Society, 2019
Non-thermal desorption of interstellar and circumstellar ice mantles on dust grains, in particula... more Non-thermal desorption of interstellar and circumstellar ice mantles on dust grains, in particular ultraviolet photon-induced desorption, has gained importance in recent years. These processes may account for the observed gas phase abundances of molecules like CO toward cold interstellar clouds. Ice mantle growth results from gas molecules impinging on the dust from all directions and incidence angles. Nevertheless, the effect of the incident angle for deposition on ice photodesorption rate has not been studied. This work explores the impact on the accretion and photodesorption rates of the incidence angle of CO gas molecules with the cold surface during deposition of a CO ice layer. Infrared spectroscopy monitored CO ice upon deposition at different angles, ultraviolet irradiation, and subsequent warm-up. Vacuum ultraviolet spectroscopy and a Ni-mesh measured the emission of the ultraviolet lamp. Molecules ejected from the ice to the gas during irradiation or warm-up were characterized by a quadrupole mass spectrometer. The photodesorption rate of CO ice deposited at 11 K and different incident angles were rather stable between 0 • and 45 •. A maximum in the CO photodesorption rate appeared around 70 • incidence deposition angle. The same deposition angle leads to the maximum surface area of water ice. Although this study of the surface area could not be performed for CO ice, the similar angle dependence in the photodesorption and the ice surface area suggests that they are closely related. Further evidence for a dependence of CO ice morphology on deposition angle is provided by thermal desorption of CO ice experiments.
Materials & Design, 2016
Materiales de Construcción, 2015
This work relates the curing conditions of concrete with the damage caused by rapid freeze-thaw c... more This work relates the curing conditions of concrete with the damage caused by rapid freeze-thaw cycles (ASTM C 666). The "potential" durability of concrete after testing is also studied. In countries with a continental climate, the curing of concrete in summer is performed under high-temperature and low-humidity conditions, and during the winter the concrete undergoes freezing and thawing. This paper shows the experimental results of the behaviour of concrete specimens cured under climatic summer conditions and then subjected to freeze-thaw cycles. Curing of the specimens includes conditions of good and bad practice in relation to wetting and protection of the concrete. Mechanical properties, cement hydration, volume and pore sizes, oxygen permeability, chloride diffusion and water penetration under pressure tests of the concrete are assessed. These tests were performed before and after the application of the freeze-thaw cycles. Statistical analysis of the correlation among variables is also included.
Construction and Building Materials, 2014
The structure of historic buildings and the materials used in their construction, along with outd... more The structure of historic buildings and the materials used in their construction, along with outdoor conditions , affect indoor temperature and humidity. The walls of San Juan Bautista Church at Talamanca de Jarama, Madrid, Spain, exhibit differences in water absorption, whose explanation is to be found in the various types of construction involved in its over seven centuries of building history, the weather conditions and the walls orientation. The south wall fluctuations in inner temperature and humidity produce 11-16 h thermal lag and a very low decrement factor ensuring comfortable interiors all year round with minimal fluctuations in temperature.
Sensors, 2019
In different disciplines of science, the knowledge of the resulting pressures in the subsoil can ... more In different disciplines of science, the knowledge of the resulting pressures in the subsoil can help to understand physical phenomena of mass exchange between the atmosphere and the terrain. The measurement of lower differential pressures is complicated given the low range of detected values. In this paper, a multisensor system has been designed and developed to measure differential pressures in radon gas transport studies. The adequacy of this system has been proven using a purpose-built pressure chamber and an automatic motion system developed by the authors. The temporal response frequencies, the pressure values measured by the sensors, and their ability to link in series were analyzed to offer a multisensor spatial and temporal mapping. At the same time, the influence of the components required for a real deployment were studied using different tube lengths and diameters, connectors, and obstructions across the operating range of the pressure sensors. The system has also been t...
NDT & E International, 2012
Physical Review Letters
The absorption of light to create Wannier-Mott excitons is a fundamental feature dictating the op... more The absorption of light to create Wannier-Mott excitons is a fundamental feature dictating the optical and photovoltaic properties of low band gap, high permittivity semiconductors. Such excitons, with an electron-hole separation an order of magnitude greater than lattice dimensions, are largely limited to these semiconductors but here we find evidence of Wannier-Mott exciton formation in solid carbon monoxide (CO) with a band gap of >8 eV and a low electrical permittivity. This is established through the observation that a change of a few degrees K in deposition temperature can shift the electronic absorption spectra of solid CO by several hundred wave numbers, coupled with the recent discovery that deposition of CO leads to the spontaneous formation of electric fields within the film. These so-called spontelectric fields, here approaching 4 × 10 7 V m −1 , are strongly temperature dependent. We find that a simple electrostatic model reproduces the observed temperature dependent spectral shifts based on the Stark effect on a hole and electron residing several nm apart, identifying the presence of Wannier-Mott excitons. The spontelectric effect in CO simultaneously explains the long-standing enigma of the sensitivity of vacuum ultraviolet spectra to the deposition temperature.
IOP Conference Series: Materials Science and Engineering, 2012
2008 IEEE International Conference on Multisensor Fusion and Integration for Intelligent Systems, 2008
... A Bluetooth AP and a PDA have been used to measure the RSSI of the received packets for diffe... more ... A Bluetooth AP and a PDA have been used to measure the RSSI of the received packets for different distances between transmitter and receiver. Fig. 7. RSSI vs. distance. The experimental data (blue dots) are fitted using (1) (solid red line), see Fig. 7. From the fit in Fig. ...
Nondestructive Testing of Materials and Structures, 2011
Ultrasonics, 2010
This paper deals with the measurement of frequency-dependent ultrasonic attenuation in strongly h... more This paper deals with the measurement of frequency-dependent ultrasonic attenuation in strongly heterogeneous materials, such as cementitious materials. To improve the measurement of this parameter on this kind of materials, a linear swept-frequency signal is used to drive an emitter transducer to conduct a through-transmission inspection in immersion. To filter out undesirable frequency content, time-frequency filtering and detection process are performed. The use of this method has been compared with two excitation techniques, the broadband and the narrowband pulses. The results obtained using the swept-frequency excitation together with the time-frequency filtering, allows the determination of the attenuation curves with high accuracy over a wide frequency range without the need for complicated equipment, and improves the effective bandwidth by using a unique pair of transducers.
Computer Physics Communications, 2014
Development of parallel codes that are both scalable and portable for different processor archite... more Development of parallel codes that are both scalable and portable for different processor architectures is a challenging task. To overcome this limitation we investigate the acceleration of the Elastodynamic Finite Integration Technique (EFIT) to model 2-D wave propagation in viscoelastic media by using modern parallel computing devices (PCDs), such as multi-core CPUs (central processing units) and GPUs (graphics processing units). For that purpose we choose the industry open standard Open Computing Language (OpenCL) and an open-source toolkit called PyOpenCL. The implementation is platform independent and can be used on AMD or NVIDIA GPUs as well as classical multi-core CPUs. The code is based on the Kelvin-Voigt mechanical model which has the gain of not requiring additional field variables. OpenCL performance can be in principle, improved once one can eliminate global memory access latency by using local memory. Our main contribution is the implementation of local memory and an analysis of performance of the local versus the global memory using eight different computing devices (including Kepler, one of the fastest and most efficient high performance computing technology) with various operating systems. The full implementation of the code is included.
Measurement Science and Technology, 2010
The combination of a staining method and an automatic digital image-processing algorithm is prese... more The combination of a staining method and an automatic digital image-processing algorithm is presented here, to measure degradation depths in cementitious materials. The measurement of those degraded depths is usually made by direct visual measurements, resulting in many errors and low reproducibility. The automatic digital image analysis (ADIA) method proposed here is mainly based on the differentiation of the degraded zone and the sound zone on the basis of the image histogram. The method comprises several steps, such as sample alignment, image calibration, background subtraction, image filtering, automatic segmentation and final measurement of the degraded depth. The algorithm developed has been used to measure the degraded depths of a set of decalcified cement mortars, made from different cement types and with varying w/b ratios. Relative to previous methods, this automatic procedure improves the precision (about 0.03 mm) and the statistical representation of the measurements. The results obtained by ADIA were compared with direct visual measurements with a very good correlation (R2 = 0.96) and a mean error of 6%.
Indagationes Mathematicae, 2003
Cement and Concrete Composites, 2013
ABSTRACT This paper presents the results of a thorough microstructural characterisation of a set ... more ABSTRACT This paper presents the results of a thorough microstructural characterisation of a set of cement mortars (made with three w/b ratios and five different cement types), degraded by the ammonium nitrate method. Both destructive and ultrasonic non-destructive techniques were used to characterise the samples. The initial calcium content of the samples plays a dominant role in both the advance of the degradation process and the degradation grade of the samples. In addition, the decalcification process kinetics and the degradation grade are modelled, using Fick’s second law of diffusion and the shrinking unreacted-core model. Two parametric equations are presented and used to estimate the decalcification process kinetics and the degradation grade using accessible microstructural parameters of the native mortars, such as the initial CaO content, the open porosity, and the cementitious matrix volume fraction. Furthermore, the degraded depth in the samples is measured using ultrasonic testing with an average error of about 10%.
Sensors, 2019
In this paper, a magnetic microwire-based sensor array embedded under the pavement is proposed as... more In this paper, a magnetic microwire-based sensor array embedded under the pavement is proposed as a weighing system at customs ports of entry. This sensor is made of a cementitious material suitable for embedding within the core of concrete structures prior to curing. The objective of this research is to verify the feasibility of stress monitoring for concrete materials using an array of cement-based stress/strain sensors that have been developed using the magnetic sensing property of an embedded microwire in a cement-based composite. Test results for microwire-based sensors and gauge sensors are compared. The strain sensitivity and their linearity are investigated through experimental testing under compressive loadings. Sensors made of these materials can be designed to satisfy specific needs and reduce costs in the production of sensor aggregates with improved coupling performance, thus avoiding any disturbance to the stress state.
Monthly Notices of the Royal Astronomical Society, 2019
Non-thermal desorption of interstellar and circumstellar ice mantles on dust grains, in particula... more Non-thermal desorption of interstellar and circumstellar ice mantles on dust grains, in particular ultraviolet photon-induced desorption, has gained importance in recent years. These processes may account for the observed gas phase abundances of molecules like CO toward cold interstellar clouds. Ice mantle growth results from gas molecules impinging on the dust from all directions and incidence angles. Nevertheless, the effect of the incident angle for deposition on ice photodesorption rate has not been studied. This work explores the impact on the accretion and photodesorption rates of the incidence angle of CO gas molecules with the cold surface during deposition of a CO ice layer. Infrared spectroscopy monitored CO ice upon deposition at different angles, ultraviolet irradiation, and subsequent warm-up. Vacuum ultraviolet spectroscopy and a Ni-mesh measured the emission of the ultraviolet lamp. Molecules ejected from the ice to the gas during irradiation or warm-up were characterized by a quadrupole mass spectrometer. The photodesorption rate of CO ice deposited at 11 K and different incident angles were rather stable between 0 • and 45 •. A maximum in the CO photodesorption rate appeared around 70 • incidence deposition angle. The same deposition angle leads to the maximum surface area of water ice. Although this study of the surface area could not be performed for CO ice, the similar angle dependence in the photodesorption and the ice surface area suggests that they are closely related. Further evidence for a dependence of CO ice morphology on deposition angle is provided by thermal desorption of CO ice experiments.
Materials & Design, 2016
Materiales de Construcción, 2015
This work relates the curing conditions of concrete with the damage caused by rapid freeze-thaw c... more This work relates the curing conditions of concrete with the damage caused by rapid freeze-thaw cycles (ASTM C 666). The "potential" durability of concrete after testing is also studied. In countries with a continental climate, the curing of concrete in summer is performed under high-temperature and low-humidity conditions, and during the winter the concrete undergoes freezing and thawing. This paper shows the experimental results of the behaviour of concrete specimens cured under climatic summer conditions and then subjected to freeze-thaw cycles. Curing of the specimens includes conditions of good and bad practice in relation to wetting and protection of the concrete. Mechanical properties, cement hydration, volume and pore sizes, oxygen permeability, chloride diffusion and water penetration under pressure tests of the concrete are assessed. These tests were performed before and after the application of the freeze-thaw cycles. Statistical analysis of the correlation among variables is also included.
Construction and Building Materials, 2014
The structure of historic buildings and the materials used in their construction, along with outd... more The structure of historic buildings and the materials used in their construction, along with outdoor conditions , affect indoor temperature and humidity. The walls of San Juan Bautista Church at Talamanca de Jarama, Madrid, Spain, exhibit differences in water absorption, whose explanation is to be found in the various types of construction involved in its over seven centuries of building history, the weather conditions and the walls orientation. The south wall fluctuations in inner temperature and humidity produce 11-16 h thermal lag and a very low decrement factor ensuring comfortable interiors all year round with minimal fluctuations in temperature.
Sensors, 2019
In different disciplines of science, the knowledge of the resulting pressures in the subsoil can ... more In different disciplines of science, the knowledge of the resulting pressures in the subsoil can help to understand physical phenomena of mass exchange between the atmosphere and the terrain. The measurement of lower differential pressures is complicated given the low range of detected values. In this paper, a multisensor system has been designed and developed to measure differential pressures in radon gas transport studies. The adequacy of this system has been proven using a purpose-built pressure chamber and an automatic motion system developed by the authors. The temporal response frequencies, the pressure values measured by the sensors, and their ability to link in series were analyzed to offer a multisensor spatial and temporal mapping. At the same time, the influence of the components required for a real deployment were studied using different tube lengths and diameters, connectors, and obstructions across the operating range of the pressure sensors. The system has also been t...
NDT & E International, 2012
Physical Review Letters
The absorption of light to create Wannier-Mott excitons is a fundamental feature dictating the op... more The absorption of light to create Wannier-Mott excitons is a fundamental feature dictating the optical and photovoltaic properties of low band gap, high permittivity semiconductors. Such excitons, with an electron-hole separation an order of magnitude greater than lattice dimensions, are largely limited to these semiconductors but here we find evidence of Wannier-Mott exciton formation in solid carbon monoxide (CO) with a band gap of >8 eV and a low electrical permittivity. This is established through the observation that a change of a few degrees K in deposition temperature can shift the electronic absorption spectra of solid CO by several hundred wave numbers, coupled with the recent discovery that deposition of CO leads to the spontaneous formation of electric fields within the film. These so-called spontelectric fields, here approaching 4 × 10 7 V m −1 , are strongly temperature dependent. We find that a simple electrostatic model reproduces the observed temperature dependent spectral shifts based on the Stark effect on a hole and electron residing several nm apart, identifying the presence of Wannier-Mott excitons. The spontelectric effect in CO simultaneously explains the long-standing enigma of the sensitivity of vacuum ultraviolet spectra to the deposition temperature.
IOP Conference Series: Materials Science and Engineering, 2012
2008 IEEE International Conference on Multisensor Fusion and Integration for Intelligent Systems, 2008
... A Bluetooth AP and a PDA have been used to measure the RSSI of the received packets for diffe... more ... A Bluetooth AP and a PDA have been used to measure the RSSI of the received packets for different distances between transmitter and receiver. Fig. 7. RSSI vs. distance. The experimental data (blue dots) are fitted using (1) (solid red line), see Fig. 7. From the fit in Fig. ...
Nondestructive Testing of Materials and Structures, 2011
Ultrasonics, 2010
This paper deals with the measurement of frequency-dependent ultrasonic attenuation in strongly h... more This paper deals with the measurement of frequency-dependent ultrasonic attenuation in strongly heterogeneous materials, such as cementitious materials. To improve the measurement of this parameter on this kind of materials, a linear swept-frequency signal is used to drive an emitter transducer to conduct a through-transmission inspection in immersion. To filter out undesirable frequency content, time-frequency filtering and detection process are performed. The use of this method has been compared with two excitation techniques, the broadband and the narrowband pulses. The results obtained using the swept-frequency excitation together with the time-frequency filtering, allows the determination of the attenuation curves with high accuracy over a wide frequency range without the need for complicated equipment, and improves the effective bandwidth by using a unique pair of transducers.
Computer Physics Communications, 2014
Development of parallel codes that are both scalable and portable for different processor archite... more Development of parallel codes that are both scalable and portable for different processor architectures is a challenging task. To overcome this limitation we investigate the acceleration of the Elastodynamic Finite Integration Technique (EFIT) to model 2-D wave propagation in viscoelastic media by using modern parallel computing devices (PCDs), such as multi-core CPUs (central processing units) and GPUs (graphics processing units). For that purpose we choose the industry open standard Open Computing Language (OpenCL) and an open-source toolkit called PyOpenCL. The implementation is platform independent and can be used on AMD or NVIDIA GPUs as well as classical multi-core CPUs. The code is based on the Kelvin-Voigt mechanical model which has the gain of not requiring additional field variables. OpenCL performance can be in principle, improved once one can eliminate global memory access latency by using local memory. Our main contribution is the implementation of local memory and an analysis of performance of the local versus the global memory using eight different computing devices (including Kepler, one of the fastest and most efficient high performance computing technology) with various operating systems. The full implementation of the code is included.
Measurement Science and Technology, 2010
The combination of a staining method and an automatic digital image-processing algorithm is prese... more The combination of a staining method and an automatic digital image-processing algorithm is presented here, to measure degradation depths in cementitious materials. The measurement of those degraded depths is usually made by direct visual measurements, resulting in many errors and low reproducibility. The automatic digital image analysis (ADIA) method proposed here is mainly based on the differentiation of the degraded zone and the sound zone on the basis of the image histogram. The method comprises several steps, such as sample alignment, image calibration, background subtraction, image filtering, automatic segmentation and final measurement of the degraded depth. The algorithm developed has been used to measure the degraded depths of a set of decalcified cement mortars, made from different cement types and with varying w/b ratios. Relative to previous methods, this automatic procedure improves the precision (about 0.03 mm) and the statistical representation of the measurements. The results obtained by ADIA were compared with direct visual measurements with a very good correlation (R2 = 0.96) and a mean error of 6%.
Indagationes Mathematicae, 2003
Cement and Concrete Composites, 2013
ABSTRACT This paper presents the results of a thorough microstructural characterisation of a set ... more ABSTRACT This paper presents the results of a thorough microstructural characterisation of a set of cement mortars (made with three w/b ratios and five different cement types), degraded by the ammonium nitrate method. Both destructive and ultrasonic non-destructive techniques were used to characterise the samples. The initial calcium content of the samples plays a dominant role in both the advance of the degradation process and the degradation grade of the samples. In addition, the decalcification process kinetics and the degradation grade are modelled, using Fick’s second law of diffusion and the shrinking unreacted-core model. Two parametric equations are presented and used to estimate the decalcification process kinetics and the degradation grade using accessible microstructural parameters of the native mortars, such as the initial CaO content, the open porosity, and the cementitious matrix volume fraction. Furthermore, the degraded depth in the samples is measured using ultrasonic testing with an average error of about 10%.