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In this work, we present a compact, bifunctional chip-based sensor setup that measures the temperature and electrical conductivity of water samples, including specimens from rivers and channels, aquaculture, and the Atlantic Ocean. For conductivity measurements, we utilize the impedance amplitude recorded via interdigitated electrode structures at a single triggering frequency. The results are well in line with data obtained using a calibrated reference instrument. The new setup holds for conductivity values spanning almost two orders of magnitude (river versus ocean water) without the need for equivalent circuit modelling. Temperature measurements were performed in four-point geometry with an on-chip platinum RTD (resistance temperature detector) in the temperature range between 2 °C and 40 °C, showing no hysteresis effects between warming and cooling cycles. Although the meander was not shielded against the liquid, the temperature calibration provided equivalent results to low conductive Milli-Q and highly conductive ocean water. The sensor is therefore suitable for inline and online monitoring purposes in recirculating aquaculture systems. [ABSTRACT FROM AUTHOR]

Previous work suggested a method that makes use of the Zwicker's loudness value of transmitted sound to validate single number quantities (SNQs) determining the airborne sound insulation of walls in dwellings. The correlation between the ranking of walls based on a SNQ, and the one based on transmitted sound loudness was used to qualify the adequacy of that SNQ. The underlying idea is that Zwicker's loudness adequately represents people's perception of loudness and that evaluations based on calculated loudness can substitute listening tests. The current work compares 16 SNQs: eight standardized or proposed in past studies, and eight new ones. The results are more robust, since more (56) walls were included, among which also highly isolating ones. SNQs are assessed for the indoor noise stimulus recently suggested by CSTB, France, and also for four filtered variants, and for two levels, the 'usual' or 'normal' level (as reported by CSTB), and that level increased by 10 dB, expressing the less common but psychologically and socially relevant situation of excessive neighbour noise. The adequacy of SNQs is analysed per wall category, (1) lightweight, (2) heavyweight, (3) CLT-based and (4) combined walls and per stimulus type. Three approaches are used to quantify the correlation between SNQ-based wall insulation performance rankings and Loudness based ones: (i) Spearman's correlation coefficient, (ii) correlation and (iii) inverse RMS residual of fitting with a parametrized function that has been empirically conceived so as to describe as good as possible the correlation SNQ-Loudness correlation behaviour for the considered population of walls. [ABSTRACT FROM AUTHOR]

ETFE cushions are used as cladding in predominantly mid to large size architectural projects. Smaller cushions are about 10 m2 in size and the biggest single cushions can be several hundreds of square metres large. They are composed of ETFE membranes a few hundred of micrometres thick. From a point of view of room acoustics, their acoustic transparency, which increases with decreasing frequency, makes them to effectively act like sound absorbers. Their voluminous nature and transparency make it challenging to measure the sound absorption coefficient of ETFE cushions in a laboratory. Using the genetic material optimizer of Odeon® software, the effective sound absorption coefficient of ETFE cushions in four rooms was extracted from room acoustic parameters, which were in turn derived from measured room impulse response data. The results were compared and interpreted by the help of theoretical modelling and measurements on small cushions in a reverberant room. There is a relatively good agreement between the three types of results, possible causes for the differences are explained in the paper. [ABSTRACT FROM AUTHOR]

This contribution intends to convince readers that by virtue of the rich physics involved, optical excitation, thermal diffusion, thermal expansion, and acoustic wave propagation, and of the optical nature of the involved excitation and detection, photoacoustic and photothermal methods offer a unique combination of features that makes them very attractive for exploitation in a wide area of scientific and technological fields that involve material property evaluation. A perspective is also given on the high potential of these methods for substantial advances beyond the state of the art in a diverse selection of scientific disciplines: biomedical diagnostics, cell and tissue mechanobiology, thin film and interface characterization, characterization of the microstructure of solids, and the physics of relaxation in glass-forming liquids. [ABSTRACT FROM AUTHOR]

This contribution intends to convince readers that by virtue of the rich physics involved, optical excitation, thermal diffusion, thermal expansion, and acoustic wave propagation, and of the optical nature of the involved excitation and detection, photoacoustic and photothermal methods offer a unique combination of features that makes them very attractive for exploitation in a wide area of scientific and technological fields that involve material property evaluation. A perspective is also given on the high potential of these methods for substantial advances beyond the state of the art in a diverse selection of scientific disciplines: biomedical diagnostics, cell and tissue mechanobiology, thin film and interface characterization, characterization of the microstructure of solids, and the physics of relaxation in glassforming liquids. [ABSTRACT FROM AUTHOR]

A numerical demonstration is given of the feasibility of a newly designed tunable asymmetric acoustic transmission device, for which the acoustic transmission coefficients for perpendicularly incident left- and right-running waves are different at a particular single frequency within a forbidden zone. The proposed device consists of a hybrid, sonic-crystal-based resonant structure with horizontal periodicity and a one-dimensional periodic rectangular acoustic grating with vertical periodicity. The former structure exhibits a wide bandgap through which only waves with particular combinations of their frequency and propagation direction can tunnel. The direction dependence of the acoustic transmission is based on the geometrical asymmetry of the placement of the grating, and on the narrowband correspondence between the diffraction angle of the grating and the allowed transmission direction through the sonic-crystal-based structure. Angular and spectral tuning are possible by changing the grating and/or the sonic crystal periodicity. The device has potential applications in underwater acoustics for asymmetric transmission systems and secure communication systems. [ABSTRACT FROM AUTHOR]

Impulsive stimulated thermal scattering (ISTS) allows one to access the structural relaxation dynamics in supercooled molecular liquids on a time scale ranging from nanoseconds to milliseconds. Till now, a heuristic semi-empirical model has been commonly adopted to account for the ISTS signals. This model implicitly assumes that the relaxation of specific heat, C, and thermal expansion coefficient, γ, occur on the same time scale and accounts for them via a single stretched exponential. This work proposes two models that assume disentangled relaxations, respectively, based on the Debye and Havriliak–Negami assumptions for the relaxation spectrum and explicitly accounting for the relaxation of C and γ separately in the ISTS response. A theoretical analysis was conducted to test and compare the disentangled relaxation models against the stretched exponential. The former models were applied to rationalize the experimental ISTS signals acquired on supercooled glycerol. This allows us to simultaneously retrieve the frequency-dependent specific heat and thermal expansion up to the sub-100 MHz frequency range and further to compare the fragility and time scale probed by thermal, mechanical, and dielectric susceptibilities. [ABSTRACT FROM AUTHOR]

This work reports results on the simultaneous spectroscopy of the specific heat and thermal expansivity of glycerol by making use of a wideband time-resolved thermal lens (TL) technique. An analytical model is presented which describes TL transients in a relaxing system subjected to impulsive laser heating. Experimentally, a set of TL waveforms, from 1 ns to 20 ms, has been recorded for a glycerol sample upon supercooling, from 300 to 200 K. The satisfactory fitting of the TL signals to the model allows the assessment of relaxation strength and relaxation frequency of the two quantities up to sub-100 MHz, extending the specific heat and thermal expansion spectroscopy by nearly three and eight decades, respectively. Fragility values, extracted from the relaxation behavior of the specific heat and the thermal expansion coefficient, are found to be similar, despite a substantial difference in relaxation strength. [ABSTRACT FROM AUTHOR]

The absorption of electromagnetic radiation by fluids or solids results in a temperature change, which, in turn, causes a change in volume resulting in the generation of a mechanical wave. When the emitted acoustic waves are recorded, the effect is referred to as a photoacoustic or optoacoustic effect. Many of the modern thermal measurement methods rely on photothermal and photoacoustic effects, including thermoreflectance, Raman scattering, Brillouin light scattering, and thermal radiation. Using two different photothermal techniques, micro-Raman thermometry and scanning thermal microscopy, Massoud I et al. i [6] measured the thermal conductivity of porous silicon, showing that both methods yielded consistent results. [Extracted from the article]

In high-resolution adiabatic scanning calorimetry (ASC) experiments, data for the temperature dependence of the specific enthalpy, h(T), and of the specific heat capacity, cp(T), are simultaneously obtained, from which the order of the phase transition and critical behaviour can be evaluated. ASC was applied to study the nematic to ferroelectric nematic phase transition (N–NF) in the liquid crystal molecule 4-[(4-nitrophenoxy)carbonyl]phenyl 2,4-dimethoxybenzoate (RM734). The N–NF was found to be very weakly first order with a latent heat Δh = 0.115 ± 0.005 J/g. The pretransitional specific heat capacity behaviour is substantially larger in the high-temperature N phase than in the low-temperature NF phase. In both phases the power-law analysis of cp(T) resulted in a critical exponent α = 0.50 ± 0.05 and amplitude ratio ANF/AN = 0.42 ± 0.03. The very small latent heat and the value of α indicate that the N–NF transition is close to a tricritical point. This is confirmed by a value of the order parameter exponent β ≈ 0.25, recently obtained from electric polarisation measurements. Invoking two-scale-factor universality, it follows from the low value of ANF/AN ratio that the size of the critical fluctuations is much larger in the NF phase than in the N phase. [ABSTRACT FROM AUTHOR]

Early detection and monitoring of heavy load induced plastic deformation in the structure is crucial for timely intervention before cracking occurs and the material completely fails. Ultrasound can be used for detecting plastic deformation provided the mechanical modulus, which can be probed via changes in velocities. This work presents a measurement scheme that makes use of optically detected, laser-induced surface acoustic waves (SAWs) for remote, real-time, online monitoring of the wave velocity during the elastic–plastic transition occurring in an aluminum plate undergoing a uniaxial tensile test and a dynamic fatigue test. Monochromatic SAWs were photoacoustically generated in a wavelength-controlled way through a transient thermal grating based laser ultrasonics excitation scheme. The SAWs were detected by a home-built photorefractive interferometer. The results reveal both regions of acceleration and slowing down, indicating that the material first stiffens and then starts to form microcracks that make it behave effectively softer for propagating SAWs. [ABSTRACT FROM AUTHOR]

The electrocaloric heat production in BaTiO 3 -based multilayer ceramic capacitors with Y5V specification was measured in a direct way by means of an adiabatic calorimeter setup. Applying an electric field of 30 MV m - 1 is found to result in a heat release of 0.94 J g - 1 and an electrocaloric temperature change of 0.46 K, in good agreement with direct results in previous studies. [ABSTRACT FROM AUTHOR]

This paper reports a multifunctional platform based on a nanocomposite hydrogel combining poly(ethylene glycol), with rhodamine B‐containing silica nanoparticles (RhB@SiO2), as temperature sensors, and gold nanorods (AuNRs) as plasmonic heaters. This composite material acts as a light‐addressable cellular matrix able to induce 3D temperature gradients locally and dynamically using the localized surface plasmon resonance (LSPR) of AuNRs under near‐infrared (NIR) laser illumination. At the same time, the temperature changes are probed locally by monitoring changes of the RhB@SiO2 NPs fluorescence. As a result of plasmonic heating, and, depending on the preparation protocol, the light‐addressable hydrogel also deforms controllably and reversibly, allowing mechanical and thermal cellular stimulation in a 3D matrix. The hydrogel deformation is quantified by means of inline holographic microscopy. This approach makes it possible to accurately and locally control and simultaneously measure temperature gradients and deformation in soft, 3D deformable materials and will enable novel platforms for studying cellular thermo‐ and mechanobiology. [ABSTRACT FROM AUTHOR]

The temperature dependence of the fluorescence spectrum of CdSe–ZnS core–shell quantum dots embedded in a polystyrene matrix is characterized between 30 °C and 60 °C. The spectrally integrated photoluminescence intensity is found to linearly decrease with -1.3%/°C. This feature is exploited in a dual coating-substrate-configuration, consisting of a layer of this nanocomposite material, acting as a temperature sensor with optical readout, on top of an optically absorbing and opaque layer, acting as a photothermal excitation source, and covering a substrate material or structure of interest. From the frequency dependence of the optically detected photothermal signal in the frequency range between 5Hz and 150 Hz, different thermal parameters of the constituent layers are determined. The fitted values of thermal properties of the different layers, determined in different scenarios in terms of the used a priori information about the layers, are found to be internally consistent, and consistent with literature values. [ABSTRACT FROM AUTHOR]

As a system of interest gets small, due to the influence of the sensor mass and heat leaks through the sensor contacts, thermal characterization by means of contact temperature measurements becomes cumbersome. Non-contact temperature measurement offers a suitable alternative, provided a reliable relationship between the temperature and the detected signal is available. In this work, exploiting the temperature dependence of their fluorescence spectrum, the use of quantum dots as thermomarkers on the surface of a fiber of interest is demonstrated. The performance is assessed of a series of neural networks that use different spectral shape characteristics as inputs (peak-based—peak intensity, peak wavelength; shape-based—integrated intensity, their ratio, full-width half maximum, peak normalized intensity at certain wavelengths, and summation of intensity over several spectral bands) and that yield at their output the fiber temperature in the optically probed area on a spider silk fiber. Starting from neural networks trained on fluorescence spectra acquired in steady state temperature conditions, numerical simulations are performed to assess the quality of the reconstruction of dynamical temperature changes that are photothermally induced by illuminating the fiber with periodically intensity-modulated light. Comparison of the five neural networks investigated to multiple types of curve fits showed that using neural networks trained on a combination of the spectral characteristics improves the accuracy over use of a single independent input, with the greatest accuracy observed for inputs that included both intensity-based measurements (peak intensity) and shape-based measurements (normalized intensity at multiple wavelengths), with an ultimate accuracy of 0.29K via numerical simulation based on experimental observations. The implications are that quantum dots can be used as a more stable and accurate fluorescence thermometer for solid materials and that use of neural networks for temperature reconstruction improves the accuracy of the measurement. [ABSTRACT FROM AUTHOR]

In photoacoustic imaging, the use of arrayed laser sources brings several advantages. Acoustic waves can be generated with flexible control of wavefronts, bringing functionality such as ultrasonic beam steering and focusing. The use of arrays reduces the optical intensity while increasing the strength of the ultrasonic wave, bringing the advantages of improved signal-to-noise ratio (SNR) while avoiding laser-induced damage. In this paper, we report a numerical model for studying the generation and shaping of acoustic wavefronts with laser arrays. The propagation of mechanical waves, photoacoustically generated by thermal expansion, is simulated and discussed in detail. In addition, a partially delayed distributed array is studied both theoretically and quantitatively. The developed model for wavefront control through time-delayed laser pulses is shown to be highly suited for the optimization of laser array generation schemes. [ABSTRACT FROM AUTHOR]

In this work, we study people's ability to discriminate between different 2D textures of walls by passive listening to a pre-recorded tongue click in an auralized echolocation scenario. In addition, the impact of artificially enhancing the early reflection magnitude by 6dB and of removing the direct component while equalizing the loudness was investigated. Listening test results for different textures, ranging from a flat wall to a staircase, were assessed using a 2 Alternative-Forced-Choice (2AFC) method, in which 14 sighted, untrained participants were indicating 2 equally perceived stimuli out of 3 presented stimuli. The average performance of the listening subjects to discriminate between different textures was found to be significantly higher for walls at 5m distance, without overlap between the reflected and direct sound, compared to the same walls at 0.8m distance. Enhancing the reflections as well as removing the direct sound were found to be beneficial to differentiate textures. This finding highlights the importance of forward masking in the discrimination process. The overall texture discriminability was found to be larger for the walls reflecting with a higher spectral coloration. [ABSTRACT FROM AUTHOR]

This article reports on impedance tube measurements of the sound absorption coefficient α (-) of selected recycled foam plastics, i.e., ethylene-vinyl acetate (EVA), polyvinyl chloride (PVC), polystyrene (PS), and polypropylene (PP), in different mixtures with a binding adhesive. The effect of the thickness of the sample on the sound absorption spectrum as well as the variability in absorption across the different samples of the same composition and thickness are discussed. For the EVA/ PP and PS/PP mixtures, the spectrum is characterized by two peaks that shift as the thickness is changing. These mixtures were also found to be the most absorbent across the whole audible frequency range. [ABSTRACT FROM AUTHOR]

A two-wave mixing photorefractive interferometry method in an anisotropic diffraction scheme, intended to selectively detect an acoustic vibration component at a specific frequency of interest in the presence of strong vibrations at other frequencies, is presented and validated by simulations and experiments. The achieved narrow-band detection is of particular interest for applications where weak vibration signals generated by nonlinear acoustic effects are to be detected with high sensitivity and without cross-talk from the large vibration components from which the acoustic nonlinearity is originating. [ABSTRACT FROM AUTHOR]

The nature of the critical behavior in the refractive index n is revisited in the framework of the complete scaling formulation. A comparison is made with the critical behavior of n as derived from the Lorentz-Lorenz equation. Analogue anomalies to those predicted for the dielectric constant &eh;, namely, a leading |t|2β singularity in the coexistence-curve diameter in the two-phase region and a |t|1-α along the critical isopleth in the one phase region, are expected in both cases. However, significant differences as regards the amplitudes of both singularities are obtained from the two approaches. Analysis of some literature data along coexistence in the two-phase region and along the critical isopleth in the one-phase region provide evidence of an intrinsic effect, independent of the density, in the critical anomalies of n. This effect is governed by the shift of the critical temperature with an electric field, which is supposed to take smaller values at optical frequencies than at low frequencies in the Hz to MHz range. [ABSTRACT FROM AUTHOR]

Dielectric constant measurements have been carried out in the one- and two-phase regions near the critical point of the polar + polar binary liquid mixture nitromethane + 3-pentanol. In the two-phase region, evidence for the |t|2β singularity in the coexistence-curve diameter has been detected, thus confirming the novel predictions of complete scaling theory for liquid-liquid criticality. In the one-phase region, an 'unusual' negative sign for the amplitude of the |t|1 - α singularity has been encountered for the first time in an upper critical solution temperature type of binary liquid mixture at atmospheric pressure. Mass density measurements have also been carried out to provide additional information related to such experimental finding, which entails an increase of the critical temperature Tc under an electric field. [ABSTRACT FROM AUTHOR]

The large critical anomaly in the isobaric heat capacity Cp,x(T) of the binary mixture nitromethane + 3-pentanol is measured using high-resolution adiabatic scanning calorimetry. The unique features of this technique provided an alternative approach to the study of the critical behavior of Cp,x(T), providing further Cp,x(T) related quantities from which valuable information could be extracted. Our data are in full agreement with the predictions of the Modern Theory of Critical Phenomena; specifically, 3D-Ising model values for the critical exponent α and the universal amplitude ratio values of the leading critical amplitudes, as well as for the first correction-to-scaling ones, provide the optimum fits to represent the experimental data. Evidence for the need of higher-order terms, i.e., first correction-to-scaling term, is given. The large value of the coefficient E for the linear temperature dependence of the background obtained is ascribed to a possible contribution of the regular linear background term, of a higher-order asymmetry term, and of the second correction-to-scaling term. Internal consistency of Cp,x(T) and its related quantities is successfully checked. [ABSTRACT FROM AUTHOR]

Six ionic liquids based on the 1-butyl-3-methylimidazolium cation have been studied. As anions Cl-, Br-, I-, [NCS]-, [N(CN)2]-, and [BF4]- were selected. The electrical conductivities were determined between 173 and 393 K based on impedance measurements in the frequency range from 0.1 to 107 Hz. The electrical conductivity increases, whereas the glass transition temperature, the fragility, and the low temperature activation energy decrease with increasing anion size. The results can be understood from the changing anion-cation interaction strength with changing anion size and from the energy landscape interpretation of the glass transition dynamics. [ABSTRACT FROM AUTHOR]

Detailed results are reported for the dielectric constant ε as a function of temperature, concentration, and frequency near the upper critical point of the binary liquid mixture nitrobenzene-tetradecane. The data have been analyzed in the context of the recently developed concept of complete scaling. It is shown that the amplitude of the low frequency critical Maxwell–Wagner relaxation (with a relaxation frequency around 10 kHz) along the critical isopleth is consistent with the predictions of a droplet model for the critical fluctuations. The temperature dependence of ε in the homogeneous phase can be well described with a combination of a (1-α) power law term (with α the heat capacity critical exponent) and a linear term in reduced temperature with the Ising value for α. For the proper description of the temperature dependence of the difference Δε between the two coexisting phases below the critical temperature, it turned out that good fits with the Ising value for the order parameter exponent β required the addition of a corrections-to-scaling contribution or a linear term in reduced temperature. Good fits to the dielectric diameter εd require a (1-α) power law term, a 2β power law term (in the past considered as spurious), and a linear term in reduced temperature, consistent with complete scaling. [ABSTRACT FROM AUTHOR]

The electrical conductivities of 1-alkyl-3-methylimidazolium tetrafluoroborate ionic liquids and of 1-hexyl-3-methylimidazolium ionic liquids with different anions were determined in the temperature range between 123 and 393 K on the basis of dielectric measurements in the frequency range from 1 to 107 Hz. Most of the ionic liquids form a glass and the conductivity values obey the Vogel-Fulcher-Tammann equation. The glass transition temperatures are increasing with increasing length of the alkyl chain. The fragility is weakly dependent on the alkyl chain length but is highly sensitive to the structure of the anion. [ABSTRACT FROM AUTHOR]

The potential and limitations of Rayleigh wave spectroscopy to characterize the elastic depth profile of heterogeneous functional gradient materials are investigated by comparing simulations of the surface acoustic wave dispersion curves of different profile-spectrum pairs. This inverse problem is shown to be quite ill posed. The method is then applied to extract information on the depth structure of a glass-ceramic (alumina) functionally graded material from experimental data. The surface acoustic wave analysis suggests the presence of a uniform coating region consisting of a mixture of Al2O3 and glass, with a sharp transition between the coating and the substrate. This is confirmed by scanning electron microscope with energy dispersive x-ray analysis. [ABSTRACT FROM AUTHOR]

The feasibility of a neural network radiometric photothermal depth profiling method is verified using well-defined artificial samples with varying optical properties across the layers. The signal calculation model is shown to be accurate and the neural network approach to solve the inverse problem is shown to be feasible. Both from simulated and experimental radiometric signals, accurate reconstructions are obtained for heat source and optical-absorption coefficient profiles. [ABSTRACT FROM AUTHOR]

An application of laser ultrasonics to investigate circumferential waves and their interaction with defects on cylindrical structures is presented. Due to the high effectiveness of the laser line-source generation regime and the broadband nature of the system, circumferential waves could be generated and detected with a wide bandwidth and an excellent signal-to-noise ratio. A clear recognition of multimode wave forms is achieved by two-dimensional Fourier transform signal processing. Measurements were also made on a cylindrical shell with a crack-like defect which was simulated by an artificial groove on the surface of the specimen. The interaction of the circumferential waves with a defect in the inner or outer surface of the thin cylindrical shell has been studied. The results may lead to an application for defect identification at the inner or outer surface of thin cylindrical shells. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

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A laser ultrasonics approach to remotely characterize the elastic and thermal properties of a coating-substrate structure, used to protect fuel claddings in lead-bismuth eutectic cooled nuclear reactors, is presented and validated with experimental results. A transient grating geometry is used for multiple wavelength excitation of thermoelastic displacements, and laser beam deflection for detection. The value of Young's modulus of the coating layer as calculated from the coating's Rayleigh velocity of 190 ± 50 GPa is in accordance with a nano-indentation measurement. Using a priori knowledge concerning the density and elastic parameters of the coating and substrate, scanning the sample allows the obtaining of a coating thickness map in a fully remote, all-optical way, with an accuracy of about 4 microns for a coating of around 20-micron average thickness. Analyzing the transient thermal grating decay yields a thermal diffusivity value of (5.0 ± 1.6) × 10 − 6 m 2 /s, in the range of low-carbon steels. The consistency of the results infers that the all-optical laser ultrasonics approach should be feasible for remote inspection of the quality of optically rough coated claddings in the harsh environment of a nuclear reactor. [ABSTRACT FROM AUTHOR]

The objectives of the present study were to investigate the acoustical properties of the very high frequencies and/or ultrasound signals produced by a repellent device and to investigate potential adverse factors as a result of short-term exposure to these signals. Potential adverse effects were evaluated perceptually with 25 young and 25 middle-aged persons, all with normal hearing thresholds, in a quiet room using different outcome measures, including a 15-item survey presented before and immediately after each condition. Spectral analyses showed that, besides emitting frequency modulated sounds in the expected frequency ranges, a faint but audible sound in the 4–5 kHz range was present. On average, a relatively short exposure to the sound produced by a repellent device did not lead to significant adverse effects. Yet, when the signal was perceived, as it was frequently for the younger population at the two lower frequencies settings (12–14 kHz, 25–25 kHz) and with 2 sources emitting, it was considered to be disturbing by several participants. Given the increasing usage of ultrasonic devices as well as the much longer exposure of high frequency and ultrasound in domestic usage, careful consideration and better guidelines are required, especially for those who are most sensitive to sound. [ABSTRACT FROM AUTHOR]

Featured Application: The work presented in the paper, relates to building physics, specifically to building acoustics. Results can be applied in engineering practice and facades development research. This paper verifies the impact of the use of an external thermal composite system (ETICS) on air-borne sound insulation. For optimum accuracy over a wide frequency range, classical microphone based transmission measurements are combined with accelerometer based vibrometry measurements. Consistency is found between structural resonance frequencies and bending wave velocity dispersion curves determined by vibrometry on the one hand and spectral features of the sound reduction index, the ETICS mass-spring-mass resonance induced dip in the acoustic insulation spectrum, and the coincidence induced dip on the other hand. Scanning vibrometry proves to be an effective tool for structural assessment in the design phase of ETICS systems. The measured spectra are obtained with high resolution in wide frequency range, and yield sound insulation values are not affected by the room acoustic features of the laboratory transmission rooms. The complementarity between the microphone and accelerometer based results allows assessing the effect of ETICS on the sound insulation spectrum in an extended frequency range from 20 Hz to 10 kHz. The modified engineering ΔR prediction model for frequency range up to coincidence frequency of external plaster layer is recommended. Values for the sound reduction index obtained by a modified prediction method are consistent with the measured data. [ABSTRACT FROM AUTHOR]

Peltier-element-based adiabatic scanning calorimetry was used to obtain equilibrium enthalpy and heat capacity curves for pure water and water-NaCl mixtures, up to the eutectic mass concentration of 23.2%, in the temperature range from -30 to $$5\,^\circ {\hbox {C}}$$ , including both the eutectic and the ordinary ice melting. From these equilibrium data, information about the transition temperatures and the heats of fusion was extracted. The transition temperatures are consistent with literature data for the phase diagram. The heats of fusion were rescaled with respect to the fraction of the sample that changes phase at each transition. These rescaled values for the eutectic transition are independent of the overall salt concentration, whereas for the ice melting there is an indication of slight decrease with increasing salt concentration. [ABSTRACT FROM AUTHOR]

The processes used to create synthetic spider silk greatly affect the properties of the produced fibers. This paper investigates the effect of process variations during artificial spinning on the thermal and mechanical properties of the produced silk. Property values are also compared to the ones of the natural dragline silk of the Nephila clavipes spider, and to unprocessed (as-spun) synthetic silk. Structural characterization by scanning pyroelectric microscopy is employed to provide insight into the axial orientation of the crystalline regions of the fiber and is supported by X-ray diffraction data. The results show that stretching and passage through liquid baths induce crystal formation and axial alignment in synthetic fibers, but with different structural organization than natural silks. Furthermore, an increase in thermal diffusivity and elastic modulus is observed with decreasing fiber diameter, trending toward properties of natural fiber. This effect seems to be related to silk fibers being subjected to a radial gradient during production. [ABSTRACT FROM AUTHOR]

A model with a cylindrically symmetric geometry and excitation is commonly simulated by a 2-D axisymmetric finite-element (FE) solver. When one part of the geometry is, however, not aligned with the remaining parts, the resulting magnetic field is no longer cylindrically symmetric and 3-D FE simulation seems unavoidable. Here, a more efficient quasi-3-D FE solver is constructed by selecting dedicated shape functions and by applying elementary toroidal coordinates in a tilted air region between different parts. [ABSTRACT FROM AUTHOR]

Ionic liquids with an ether-functionalised cation and the bis(2-ethylhexyl)phosphate anion show thermomorphic behaviour in water, with a lower critical solution temperature. These ionic liquids are useful for homogeneous liquid–liquid extraction of first-row (3d) transition metals. [ABSTRACT FROM AUTHOR]

A stroboscopic full-field imaging technique based on photorefractive interferometry for the visualization of rapidly changing surface displacement fields by using of a standard charge-coupled device (CCD) camera is presented. The photorefractive buildup of the space charge field during and after probe laser pulses is simulated numerically. The resulting anisotropic diffraction upon the refractive index grating and the interference between the polarization-rotated diffracted reference beam and the transmitted signal beam are modeled theoretically. The method is experimentally demonstrated by full-field imaging of the propagation of photoacoustically generated surface acoustic waves with a temporal resolution of nanoseconds. The surface acoustic wave propagation in a 23 mm x 17 mm area on an aluminum plate was visualized with 520 x 696 pixels of the CCD sensor, yielding a spatial resolution of 33 µm. The short pulse duration (8 ns) of the probe laser yields the capability of imaging SAWs with frequencies up to 60 MHz. [ABSTRACT FROM AUTHOR]