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Joining of metals to polymers is increasing among various industries because of its ability to produce lightweight hybrid products with tailored properties. Common joining methods, such as adhesive bonding and mechanical fastening, require adding a third material which might involve hazardous chemicals or add extra weight and stress concentration points to the component. On the other hand, Laser-Assisted Metal – Polymer joining (LAMP) is a contactless, rapid, highly precise and energy-efficient technique, that produces autogenous and miniaturized joints. It was already demonstrated that surface pretreatment prior to the welding process has a significant impact on the joint performance by modifying surface chemistry and topography, promoting chemical bonding and mechanical interlocking. This research aims at expanding the understanding of the effects of surface properties on the joint’s performance by investigating their influence on interfacial thermal transfer. While increased surface roughness of metallic partner is expected to improve LAMP joint performance by promoting mechanical interlocking, it is hypothesized that a smoother surface would improve the joint quality by enhancing the interfacial thermal transfer during the welding process, resulting in a larger area of molten polymer at the interface and a better joint performance. In this research, aluminum (Al1050) and titanium (Ti64) were joined with polyamide (PA6.6). Initially, laser welding parameters were optimized and kept constant during all surface pretreatments’ investigations. Preliminary surface pretreatments, using short-pulsed laser ablation and atmospheric plasma pretreatment, were conducted on Al1050 – PA6.6 to analyze the effects of surface composition and topography on joint quality and performance, and to optimize interfacial adhesion. Results show a correlation between increased surface oxidation and surface energy with improved interfacial adhesion and joint resistance to shear failure. Com

Joining of metals to polymers is increasing among various industries because of its ability to produce lightweight hybrid products with tailored properties. Common joining methods, such as adhesive bonding and mechanical fastening, require adding a third material which might involve hazardous chemicals or add extra weight and stress concentration points to the component. On the other hand, Laser-Assisted Metal – Polymer joining (LAMP) is a contactless, rapid, highly precise and energy-efficient technique, that produces autogenous and miniaturized joints. It was already demonstrated that surface pretreatment prior to the welding process has a significant impact on the joint performance by modifying surface chemistry and topography, promoting chemical bonding and mechanical interlocking. This research aims at expanding the understanding of the effects of surface properties on the joint’s performance by investigating their influence on interfacial thermal transfer. While increased surface roughness of metallic partner is expected to improve LAMP joint performance by promoting mechanical interlocking, it is hypothesized that a smoother surface would improve the joint quality by enhancing the interfacial thermal transfer during the welding process, resulting in a larger area of molten polymer at the interface and a better joint performance. In this research, aluminum (Al1050) and titanium (Ti64) were joined with polyamide (PA6.6). Initially, laser welding parameters were optimized and kept constant during all surface pretreatments’ investigations. Preliminary surface pretreatments, using short-pulsed laser ablation and atmospheric plasma pretreatment, were conducted on Al1050 – PA6.6 to analyze the effects of surface composition and topography on joint quality and performance, and to optimize interfacial adhesion. Results show a correlation between increased surface oxidation and surface energy with improved interfacial adhesion and joint resistance to shear failure. Com

This study explores the features of process of drying internal heat and mass transfer in wood in the conditions of essentially noniso-thermal transfer of moisture. The process of capillary conductivity of wood is analyzed on the model of colloidal capillary-porous solid. The density of moisture flows caused by the phenomenon of thermal and hydraulic conductivity is determined. Previously experimentally established fact of influence on the process of moisture removal of the current moisture content of wood is analytically confirmed. De-pendences of the phase transition criterion taking into account the direction of the temperature gradient and wood moisture are analytically obtained. Recommendations are given to determine the thermogradient coefficient taking into account the asymmetry of moisture flows depending on the direction of the temperature gradient, and also for the correction in the entry form of the equation of moisture transfer with the influence of the effect of thermal and hydraulic conductivity. © 2018 CEUR-WS. All rights reserved.

This study explores the features of process of drying internal heat and mass transfer in wood in the conditions of essentially noniso-thermal transfer of moisture. The process of capillary conductivity of wood is analyzed on the model of colloidal capillary-porous solid. The density of moisture flows caused by the phenomenon of thermal and hydraulic conductivity is determined. Previously experimentally established fact of influence on the process of moisture removal of the current moisture content of wood is analytically confirmed. De-pendences of the phase transition criterion taking into account the direction of the temperature gradient and wood moisture are analytically obtained. Recommendations are given to determine the thermogradient coefficient taking into account the asymmetry of moisture flows depending on the direction of the temperature gradient, and also for the correction in the entry form of the equation of moisture transfer with the influence of the effect of thermal and hydraulic conductivity. © 2018 CEUR-WS. All rights reserved.

In borehole heat exchangers (BHE), grouting material plays a significant role in the heat transfer between the ground and the heat carrier fluid in the pipes. To guarantee proper sealing capacity of the grouting materials, the grout must also fulfill suitable hydraulic and mechanical properties. This paper evaluates the performance of various grouting materials, through thermal, hydraulic and mechanical laboratory characterizations. In particular, the addition of graphite powder to improve the thermal properties of grouting material is tested. In parallel, the characteristics of two different widely used commercial grouting materials (i.e. bentonite-based and silica sand-based materials) are also investigated. Afterwards, the specific heat exchange rate and the borehole resistance of borehole heat exchangers are assessed experimentally in a 1 × 1 × 1 m3 sandbox under, successively, dry sand and fully water-saturated sand conditions. During the operations, the monitored temperatures in the sandbox are in good agreement with analytical predictions. This study demonstrates that the homemade admixture prepared with 5% natural flake graphite can be considered as an appropriate grout for BHEs regarding to its rheological and thermo-physical properties. Thermally-enhanced grouting can be of significant interest in a high thermal conductivity ground (such as saturated sand) because it minimizes the thermal resistance of the BHE. © 2014 Elsevier Ltd. All rights reserved., SCOPUS: ar.j, info:eu-repo/semantics/published

In borehole heat exchangers (BHE), grouting material plays a significant role in the heat transfer between the ground and the heat carrier fluid in the pipes. To guarantee proper sealing capacity of the grouting materials, the grout must also fulfill suitable hydraulic and mechanical properties. This paper evaluates the performance of various grouting materials, through thermal, hydraulic and mechanical laboratory characterizations. In particular, the addition of graphite powder to improve the thermal properties of grouting material is tested. In parallel, the characteristics of two different widely used commercial grouting materials (i.e. bentonite-based and silica sand-based materials) are also investigated. Afterwards, the specific heat exchange rate and the borehole resistance of borehole heat exchangers are assessed experimentally in a 1 × 1 × 1 m3 sandbox under, successively, dry sand and fully water-saturated sand conditions. During the operations, the monitored temperatures in the sandbox are in good agreement with analytical predictions. This study demonstrates that the homemade admixture prepared with 5% natural flake graphite can be considered as an appropriate grout for BHEs regarding to its rheological and thermo-physical properties. Thermally-enhanced grouting can be of significant interest in a high thermal conductivity ground (such as saturated sand) because it minimizes the thermal resistance of the BHE. © 2014 Elsevier Ltd. All rights reserved., SCOPUS: ar.j, info:eu-repo/semantics/published

We investigate the use of quartz optically stimulated luminescence (OSL) dating for determining fluvial overbank sedimentation rates over decades to centuries. For the study we took 11 samples from three cores from an embanked floodplain along the River Waal (Rhine) near Neerijnen (The Netherlands). We propose a measurement protocol for young fluvial quartz based on the single-aliquot regenerative dose procedure. Parameters for the protocol are chosen to isolate the fast OSL component, eliminate an ultrafast OSL component and avoid thermal transfer. The protocol shows excellent dose recovery and recycling ratios. For each sample, a Gaussian is fitted to the lower part of the equivalent dose distribution to obtain an estimate of the burial dose. We discuss the validity of the OSL ages using internal and external controls, and conclude that there is no evidence for large systematic offsets in the OSL ages. OSL based sedimentation rates are between ∼3 and 8 mm/a, in line with previous estimates.

We investigate the use of quartz optically stimulated luminescence (OSL) dating for determining fluvial overbank sedimentation rates over decades to centuries. For the study we took 11 samples from three cores from an embanked floodplain along the River Waal (Rhine) near Neerijnen (The Netherlands). We propose a measurement protocol for young fluvial quartz based on the single-aliquot regenerative dose procedure. Parameters for the protocol are chosen to isolate the fast OSL component, eliminate an ultrafast OSL component and avoid thermal transfer. The protocol shows excellent dose recovery and recycling ratios. For each sample, a Gaussian is fitted to the lower part of the equivalent dose distribution to obtain an estimate of the burial dose. We discuss the validity of the OSL ages using internal and external controls, and conclude that there is no evidence for large systematic offsets in the OSL ages. OSL based sedimentation rates are between ∼3 and 8 mm/a, in line with previous estimates.

We investigate the use of quartz optically stimulated luminescence (OSL) dating for determining fluvial overbank sedimentation rates over decades to centuries. For the study we took 11 samples from three cores from an embanked floodplain along the River Waal (Rhine) near Neerijnen (The Netherlands). We propose a measurement protocol for young fluvial quartz based on the single-aliquot regenerative dose procedure. Parameters for the protocol are chosen to isolate the fast OSL component, eliminate an ultrafast OSL component and avoid thermal transfer. The protocol shows excellent dose recovery and recycling ratios. For each sample, a Gaussian is fitted to the lower part of the equivalent dose distribution to obtain an estimate of the burial dose. We discuss the validity of the OSL ages using internal and external controls, and conclude that there is no evidence for large systematic offsets in the OSL ages. OSL based sedimentation rates are between ∼3 and 8 mm/a, in line with previous estimates.

We performed a time-dependent simulation of thermal transfer in a circuit board, comparing the effects of using four different die-attach materials with high-power silicon carbide diodes. This simulation attempted to reproduce the results of a laboratory experiment in which thermal measurements were made of circuit boards under a time-varying load., The original document contains color images.

In the assessment of doses received from a nuclear accident, considerable attention has been paid to retrospective dosimetry using the optically stimulated luminescence (OSL) of heated materials such as bricks and tiles. Quartz extracted from these artefacts was heated during manufacture;, this process releases all the prior trapped charge and simultaneously sensitises the quartz. Unfortunately unheated materials such as mortar and concrete are more common in industrial sites and particularly in nuclear installations. These materials are usually exposed to daylight during quarrying and construction, but in general this exposure is insufficient to completely empty (bleach) any geological trapped charge. This leads to a distribution of apparent doses in the sample at the time of construction with only some (if any) grains exposed to sufficient light to be considered well bleached for OSL dosimetry. The challenge in using such materials as retrospective dosemeters, is in identifying these well-bleached grains when an accident dose has been superimposed on the original dose distribution. We investigate here, using OSL, the background dose in three different mortar samples: render, whitewash and inner wall plaster from a building built in 1964. These samples are found to be both poorly bleached and weakly sensitive (only 0.3% of grains giving a detectable dose response). We study thermal transfer in single grains of quartz, investigate the grain-size dependence of bleaching in the size range 90-300 mum and compare the dose-distributions obtained from small aliquots and single-grain procedures. A comparison of three different methods viz. (a) first 5%, (b) probability plot and (c) comparison of internal and external uncertainties, is made for equivalent dose estimation. The results have implications for accident dosimetry, archaeological studies and dating of poorly bleached sediments. (C) 2003 Elsevier Ltd. All fights reserved.