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The purpose of this paper was to develop the methodology of thick-film/low temperature co-fired ceramic (LTCC) multilayer thermoelectric microgenerator fabrication including the procedure of silver-nickel thermocouples integration with LTCC.

To miniaturize the structures and to increase the output parameters (generated voltage, electrical power), the microgenerator was designed as multilayer systems. It allows to reduce size of the system and to increase the number of thermocouples integrated inside the structure. It also protects buried thermocouples against exposure to harmful external factors (e.g. moisture, oxidation and mechanical exposures). As a substrate, LTCC was used. For the thermocouples fabrication, thick-film pastes based on silver and nickel were chosen. Ag/Ni thermocouple has nearly three times higher Seebeck coefficient and 30 per cent lower electrical resistance than the combination of Ag/PdAg used in previous works of the author.

A multi-layer thick-film thermoelectric generator based on LTCC and Ag, Ni pastes was fabricated. Thirty Ag/Ni thermocouples were precisely screen-printed on few layers. Thermocouples’ arms are 15 mm long and about 150 μm wide. Interlayer connections (via-holes filled with conductive paste) provided the electrical contact between the layers. The biggest fabricated harvester consisted of 90 miniature thermocouples buried inside the LTCC.

The paper presents the results of research that provided to optimize the co-firing process of the LTCC/Ni set. In the result, the methodology of co-firing of silver-nickel thermocouples and LTCC ceramic was elaborated. Also, the methodology of fabrication of miniature thermoelectric energy harvesters was optimized.

Ultrasonic additive manufacturing (UAM) is a rapid prototyping process through which multiple thin layers of material are sequentially ultrasonically welded together to form a finished part. While previous research into the peak temperatures experienced during UAM have been documented, a thorough examination of the heating and cooling curves has not been conducted to date.

For this study, UAM weldments made from aluminum 3003‐H18 tapes with embedded Type‐K thermocouples were examined. Finite element modeling was used to compare the theoretical thermal diffusion rates during heating to the observed heating patterns. A model was used to calculate the effective thermal diffusivity of the UAM build on cooling based on the observed cooling curves and curve fitting analysis.

Embedded thermocouple data revealed simultaneous temperature increases throughout all interfaces of the UAM build directly beneath the sonotrode. Modeling of the heating curves revealed a delay of at least 0.5 seconds should have existed if heating of lower interfaces was a result of thermal diffusion alone. As this is not the case, it was concluded that ultrasonic energy is absorbed and converted to heat at every interface beneath the sonotrode. The calculated thermal diffusivity of the build on cooling was less than 1 percent of the reported values of bulk aluminum, suggesting that voids and oxides along interfaces throughout the build may be inhibiting thermal diffusion through thermal contact resistance across the interface.

This work systematically analyzed the thermal profiles that develop during the UAM process. The simultaneous heating phenomenon presented here has not been documented by other research programs. The findings presented here will enable future researchers to develop more accurate models of the UAM process, potentially leading to improved UAM bond quality.

The cross‐correlation flow measurement technique, applied for measuring the coolant flow rate in a nuclear reactor, was calibrated with the use of numerical simulations of turbulent flow. The three‐dimensional domain was collapsed into two dimensions. With a two‐dimensional calculation of steady‐state flow with transient thermal characteristics the response of thermocouples to a temperature variation was calculated. By cross‐correlating the calculated thermocouple responses, the link between total flow rate and measured transit times was made. The reliability of the calibration was estimated at ±4.6%. In addition, a measured velocity profile effect was successfully predicted.

This paper aims to measure peak temperatures and cooling rates for distinct locations of thermocouples in the butt weld joint of mild steel plates. For experimental measurement of peak temperatures, K-type thermocouples coupled with a data acquisition system were used at predetermined locations. Thereafter, Rosenthal’s analytical models for thin two-dimensional (2D) and thick three-dimensional (3D) plates were adopted to predict peak temperatures for different thermocouple positions. A finite element model (FEM) based on an advanced prescribed temperature approach was adopted to predict time-temperature history for predetermined locations of thermocouples.

Comparing experimental and Rosenthal analytical models (2D and 3D) findings show that predicted and measured peak temperatures are in close agreement, while cooling rates predicted by analytical models (2D, 3D) show significant variation from measured values. On the other hand, 3D FEM simulation predicted peak temperatures and cooling rates for different thermocouple positions are close to experimental findings.

The inclusion of filler metal during simulation of welding rightly replicates the real welding situation and improves outcomes of the analysis.

The present study is an original contribution to the field of welding technology.

To improve productivity and reach better quality in assembling, measurements and proper process controlling are a necessary factor. This study aims to focus on the monitoring heat-level-based vapour phase reflow soldering (VPS), where – as it was found – different thermocouple constructions can affect the set parameters of the oven and resulting soldering profiles significantly.

The study experiments showed significant alteration of the heating profiles during the process of the reflowing using different construction of k-type thermocouples. In a heat-level-based VPS oven, polytetrafluoroethylene (PTFE), perfluoroalkoxy (PFA) gas and water-resistant, fibreglass, thin PFA and ultrathin PFA-covered thermocouples were tested with ±1 °C precision. The oven parameters were swept according to the heating power; the length of the introduced thermocouple cables was also taken into account. An FR4-based sample PCB was used for monitoring the temperature.

According to the results, due to the mass and volume of the thermocouples’ wires, different transients were observed on the resulting soldering profiles on the same sample PCB. The thermocouples with lower thermal mass result in faster profiles and significantly different heating factor values compared to the thermocouples that have larger thermal mass. Consequently, the length of the thermocouple wires put in the oven has also considerable effect on the heat transfer of the PCB inside the oven as well.

The paper shows that the thermocouple construction must be taken into account when setting up a required soldering profile, while the thermal mass of the wires might cause a significant difference in the prediction of the actual and expected soldering temperatures.

This paper presents a new multi‐channel temperature measurement system (MCTMS) with small size, light weight and low power consumption for the microgravity fluid experiment of drop Marangoni migration on SZ‐4 spaceship, a test module of the manned space mission of China.

The MCTMS, with a commercial‐off‐the‐shelf (COTS) component monolithic thermocouple amplifier with cold junction compensation AD595, is designed to measure temperature gradient field of up to 6 type T thermocouples Cu‐Constantan for microgravity fluid experiment. Through an analog multiplexer, the very small signal amplitude of the six‐channel temperatures can be acquired and amplified by the same monolithic thermocouple amplifier to retain the consistency of the six channels. A fully mission analysis and evaluation on the COTS component was taken into account before it was used in the thermal and radiation environment of space.

Using the COTS component in space can increase the system performance and considerably reduce the size, weight, power consumption and the overall complexity of the system. The measurement resolution of the MCTMS reaches 0.1°C because of the utilization of the COTS with high performance. In addition, the transfer function of the AD595 was deduced for type T thermocouples.

This paper suggests an easy way of measuring temperature for microgravity fluid experiment on spacecraft. Using a COTS component on spacecraft, also, is a new practical case study, which is more suitable for on‐board implementation. The MCTMS, presented in this work, has run in‐orbit successfully on SZ‐4 spaceship and the experiment result in space is reported.

The purpose of this work was fabrication of a small energy harvester.

The multilayer thermoelectric power generator based on thick-film and low temperature co-fired ceramic (LTCC) technology was fabricated. Precise paths printing method was used to fabricate Ag/Ni and Ag/PdAg thermocouples on a number of unfired LTCC tapes. The tapes were put together to form a multilayer stack. The via holes were used to make the electrical connections between adjacent layers. Finally, the multilayer stack was fired in the appropriate thermal profile.

It consists of 450 thermocouples and generates output voltage of about 0.45 V and output electrical power of about 0.13 mW when a temperature difference along the structure is 135°C. In the paper, individual stages of energy harvester fabrication process as well as its output parameters are presented.

Miniaturized thermoelectric energy harvester based on thick-film and LTCC technology was fabricated. As materials, metal-based pastes were used. This is the first paper where multilayer thermoelectric harvester, fabricated with the aid of LTCC technology, was described.

The purpose of this paper is to investigate the possible application of thick‐film, metal‐based thermocouples to microsystems power supply. The subject of matter was development of the procedure of thick‐film thermopile miniaturisation.

The aptitude of four photoimageable inks (based on silver or silver‐palladium) to fabrication of miniaturised thermocouples' arms was investigated. The object of interest was their compatibility with different kinds of low temperature cofired ceramic (LTCC) substrates, maximum resolution, shrinkage and electrical resistivity. Usage of the laser shaping technique to fabrication of narrow thermocouples' arms was also subject of matter. After tests and processes optimization both techniques were combined to fabricate the thick‐film Ag/Ni microthermopile.

Most of investigated inks were compatible with all tested LTCC tapes – fired as well as unfired (green tapes). Photoimageable inks technique can be successfully used for thermocouples' arms miniaturization. 40 μm/40 μm line/spaces resolution can be easily achieved. Combining this technique with laser shaping enabled microthermopile fabrication. It consisted of 42 Ag (photoimageable)/Ni (laser shaped) thermocouples. Arms width was 40 μm and 225 μm (Ag‐ and Ni‐arm, respectively), spaces between them – 65 μm. Overall, width of single thermocouple was smaller than 0.4 mm.

Fabrication of microthermopile consisting of several hundreds of thick‐film thermocouples will be possible if described procedure is applied. Such microgenerator will generate output power sufficient to supply some microsystems or microelectronic circuits.

The properties of four photoimageable inks were investigated as well as their compatibility with five different LTCC substrates (fired and unfired). Procedure of thick‐film microthermopile fabrication using photoimageable inks technique combined with laser shaping was proposed for the first time.

Technology advances in the field of temperature measurement have led to a huge variety of sensors and measuring instruments now being available for making accurate measurements at relatively low costs. This article takes a “back to basics” look at three of the most popular temperature sensor technologies and offers advice on how to avoid the many pitfalls and traps that often destroy the accuracy of a temperature measuring system.

In recent times, the use of steel sections with web openings has become common as slim floor beams because they offer a reduction in weight of the steelwork, accommodate services within the floor depth and provide the composite action. The composite action in these beams is achieved either through the concrete dowels or through concrete plugs. Though these web openings offer several benefits in slim floor beams, they induce the material discontinuity in the steel web, which may affect their shear capacity and/or thermal behaviour. The purpose of this study is to investigate the thermal behaviour of slim floor beams with web openings in fire.

This research presents findings from experimental and analytical investigations conducted to study the thermal behaviour of slim floor beams with web openings in fire. For this purpose, an experimental investigation was conducted, which shows that the presence of web openings has a major influence on temperature development across the steel section as well as along the span of these beams. The behaviour of the tested slim floor beam is validated using finite element modelling. The validated finite element model is then used to conduct a sensitivity study to analyse the influence of different opening spacings, sizes and shapes on the thermal performance of slim floor beams in fire.

Test results show that the presence of web openings has a major influence on temperature development across the steel section as well as along the span of these beams. Temperatures on the web below the openings are found to be higher as compared to those recorded on the adjacent solid steel web. It is also observed that temperatures on the steel web above the openings are lesser than those on the adjacent solid steel web. Parametric studies conducted using the verified analytical modelling methods show that different opening spacings, sizes and shapes have a variable impact on the thermal behaviour of slim floor beams in fire. Closely spaced and larger opening sizes were found to have a more severe influence on their thermal behaviour in fire as compared to widely spaced and smaller openings. It was also found that the behaviour of these beams is influenced by the shape of the openings with rectangular openings resulting in more severe thermal distributions as compared to circular openings.

The findings from this research study are highly valuable as they contribute to the existing knowledge database. There is a lack of experimental and analytical investigation on performance of slim floor beams with web openings at elevated temperatures. The results and conclusions from this study will help in developing innovative designs for slim floor beams and will help in reducing the fire related risk associated with structures comprising of slim floor beams with web openings.