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Controlling thermal energy transfer at the nanoscale and thermal properties has become critically important in many applications since it often limits device performance. In this study, the effects on thermal conductivity arising from the nanoscale structure of free-standing nanocrystalline silicon films and the increasing surface-to-volume ratio when fabricated into suspended optomechanical nanobeams are studied. Thermal transport and elucidate the relative impact of different grain size distributions and geometrical dimensions on thermal conductivity are characterized. A micro time-domain thermoreflectance method to study free-standing nanocrystalline silicon films and find a drastic reduction in the thermal conductivity, down to values below 10 W m–1 K–1 is used, with a stronger decrease for smaller grains. In optomechanical nanostructures, this effect is smaller than in membranes due to the competition of surface scattering in decreasing thermal conductivity. Finally, a novel versatile contactless characterization technique that can be adapted to any structure supporting a thermally shifted optical resonance is introduced. The thermal conductivity data agrees quantitatively with the thermoreflectance measurements. This study opens the way to a more generalized thermal characterization of optomechanical cavities and to create hot-spots with engineered shapes at the desired position in the structures as a means to study thermal transport in coupled photon-phonon structures., This work was supported by the European Commission FET Open project PHENOMEN (G.A. Nr. 713450). ICN2 was supported by the S. Ochoa program from the Spanish Research Agency (AEI, grant no. SEV-2017-0706) and by the CERCA Programme / Generalitat de Catalunya. ICN2 authors acknowledge the support from the Spanish MICINN project SIP (PGC2018-101743-B-I00). D.N.U. and M.F.C. acknowledge the support of a Ramón y Cajal postdoctoral fellowship (RYC-2014-15392) and a Severo Ochoa studentship, respectively. E.C.A. acknowledges financial support from the EU FET Open Project NANOPOLY. (GA 829061). A.M. acknowledges support from Ministerio de Ciencia, Innovación y Universidades (grant PGC2018-094490-B, PRX18/00126) and Generalitat Valenciana (grants PROMETEO/2019/123, and IDIFEDER/2018/033).

Climate change (CC) is predominantly connected to greenhouse gas (GHG) emissions from the construction sector. It is clear how it is necessary to rethink construction materials in order to reduce GHG emissions. Among the various strategies proposed, recent research has investigated the potential of smart materials. This study in particular aims to develop an innovative building component that combines high energy performance with reduced thickness and weight. For this reason, the potential of Phase Change Materials (PCM) in cement-based mixes is investigated, comparing the performance of a traditional mix with two innovative mixes made with the addition of 3% and 7% PCM. This work characterizes the new material, analyzing its mechanical and thermal performance, highlighting how the mix strength decreases as the PCM ratio increases, however, both mixes may be considered suitable for masonry structures and may be classified as M5 and M15. Furthermore, from the analysis of the thermal performance, it emerges that the mix presents good behavior in terms of insulating properties.

Heat dissipation and thermal management are central challenges in various areas of science and technology and are critical issues for the majority of nanoelectronic devices. In this review, we focus on experimental advances in thermal characterization and phonon engineering that have drastically increased the understanding of heat transport and demonstrated efficient ways to control heat propagation in nanomaterials. We summarize the latest device-relevant methodologies of phonon engineering in semiconductor nanostructures and 2D materials, including graphene and transition metal dichalcogenides. Then, we review recent advances in thermal characterization techniques, and discuss their main challenges and limitations., ICN2 is supported by the Severo Ochoa program, the Spanish Research Agency (AEI, grant no. SEV-2017-0706) and the CERCA Programme/Generalitat de Catalunya. Authors acknowledge support from Spanish MICINN project SIP (PGC2018-101743-B-I00), and the EU project NANOPOLY (GA 289061).

Datacenters are at the heart of the AI, Industry 4.0 and cloud revolution. A datacenter contains a large number of computing nodes hosted in a large temperature-controlled room. Due to the increasing total power and power density of computing nodes, the overall datacenter compute capacity is often capped by peak power consumption and temperature bottlenecks. To preserve the homogeneous performance assumption between all the nodes, complex cooling solution are required, but they might not be sufficient. In this work, we analysed and characterised the thermal properties of a Tier0 datacenter deploying advanced hybrid cooling technologies: specifically, we studied the spatial and temporal heterogeneity during production and cooling emergency hazards. This paper gives first quantitative evidence of thermal bottlenecks in real-life production workload, showing the presence of significant spatial thermal heterogeneity which could be exploited by thermal-aware job scheduling and datacenter-room run-time workload adaptation and distribution.

The authors would like to acknowledge to the staff of the Hospital Universitario Clínico San Cecilio, Granada, Spain, for their support and use of the facilities. We also thank the reviewers for their useful and constructive comments and suggestions which have improved this paper., Safe quality control of radiotherapy treatments lies in reliable dosimetric sensors. Currently, ionization chambers and solid-state diodes along with electrometers as readout systems are accomplishing this task. In this work, we present a well-known and low-cost semiconductor sensor, the light-dependent resistor (LDR), as an alternative to the existing sensing devices for dosimetry. To demonstrate this, a complete characterization of the response to radiation of commercial LDRs has been conducted in terms of sensitivity, reproducibility and thermal correction under different bias voltages. Irradiation sessions have been applied under the common conditions in radiotherapy treatments using a hospital linear accelerator. Moreover, the same electrometer used for the ionization chamber has also been successfully used for LDRs. In comparison with the sensitivity achieved for the ionization chamber (0.2 nC/cGy at 400 V bias voltage), higher sensitivities have been measured for the proposed LDRs, ranging from 0.24 to 1.04 nC/cGy at bias voltages from 30 to 150 V, with a reproducibility uncertainty among samples of around 10%. In addition, LDR temperature dependence has been properly modeled using the simple thermistor model so that an easy thermal drift correction of dose measurements can be applied. Therefore, experimental results show that LDRs can be a reliable alternative to dosimetric sensors with the advantages of low size, affordable cost and the fact that it could be adopted with minimal changes in routine dosimetry quality control since the same readout system is fully compatible., Junta de Andalucía B-TIC-468-UGR18 PI-0505-2017, European Union (EU)

This paper presents a literature review about aerogel-based products for building, focusing on the plasters used within the architectural restoration sector. Aerogel has entered the construction field in the last two decades as a component of many insulation products, due to its high thermal performance. Aerogel-based plasters allow the matching of high thermal performance and limited thickness. This makes them suitable when retrofitting an existing building and also when restoring a heritage building. We analyze the results of recent research, focusing on the most commonly used methods for assessing the thermal performances and durability of aerogel-based plasters. As a result of this review, we propose a guideline for manufacturing samples destined for laboratory tests.

Building performance is strongly influenced by the performance of their structural parts, consequently affecting annual energy demands. The thermal characterization of building components can be achieved thanks to the knowledge of their internal layers and the thermal properties of each material. Considering existing buildings, technical data may be unidentified and heat transfer phenomena between walls and environments can be influenced by air-conditioning systems and local thermo-fluid dynamic conditions. Moreover, the conversion of an existing building into a Nearly Zero Energy Building (NZEB) requires accurate measurements and simulations compared with Standards suggestions, based on simplified procedures. Therefore, on-site surveys become fundamental. Standards suggestions can help engineers or technicians to define some unknown information related to heat transfer coefficients and thermo-physical properties. Nevertheless, can Standards' suggestions be considered reliable in every situation? This paper tries to answer this question, debating some investigations conducted in the last years and proposing a methodological approach.

Almost 15 years have gone ever since the discovery of graphene as a single atom layer. Numerous papers have been published to demonstrate its high electron mobility, excellent thermal and mechanical as well as optical properties. We have recently seen more and more applications towards using graphene in commercial products. This paper is an attempt to review and summarize the current status of the research of the thermal properties of graphene and other 2D based materials including the manufacturing and characterization techniques and their applications, especially in electronics and power modules. It is obvious from the review that graphene has penetrated the market and gets more and more applications in commercial electronics thermal management context. In the paper, we also made a critical analysis of how mature the manufacturing processes are; what are the accuracies and challenges with the various characterization techniques and what are the remaining questions and issues left before we see further more applications in this exciting and fascinating field., YF, JH, YL, AZ, MK and JL acknowledge the financial support from The Swedish National Science Foundation (VR under the contract No 621-2007-4660), The Swedish Foundation for Strategic Research (SSF) under contract (No SE13-0061), the Swedish Board for innovation under the Siografen program and from the Production Area of Advance at Chalmers University of Technology, Sweden. SC, YZ and JL acknowledge the financial support by the Key R&D Development Program from the Ministry of Science and Technology of China with the contract No: 2017YFB040600 and the National Natural Science Foundation of China (No. 51872182). XX is supported the National Natural Science Foundation of China (No. 11674245 & No. 11890703). MS and CMST acknowledge financial support from the CERCA programme/Generalitat de Catalunya, the Severo Ochoa Centres of Excellence programme, funded by the Spanish Research Agency (AEI, Grant No. SEV-2017-0706).

International audience; The breakdown voltage of GaN/Si high electron mobility transistors (HEMTs) for power electronics has shown to be improved by removing the silicon substrate. The drawback to this approach is the increase in the device's thermal resistance which limits the power dissipation that the device can achieve before severe degradation. This study shows the ability to improve the thermal dissipation of these devices by depositing Copper (Cu) below Aluminum Nitride (AlN) filled etched back GaN-on-Si HEMTs. The device's channel temperature is measured via Raman thermometry. The device's transient thermal dynamics is investigated via transient thermoreflectance imaging and the temperature profile across the gate metal is monitored. In addition to the device's thermal properties, residual stress analysis of the GaN channel is performed via photoluminescence. A notable decrease in the tensile residual stress is observed with the removal of the substrate and the addition of the AlN and Cu layers. Overall, the backside copper is shown to decrease the gate temperature of the etched backed AlN filled devices while maintaining a high breakdown voltage.

The design, fabrication, and use of a hotspot-producing and temperature-sensing resistance thermometer for evaluating the thermal properties of low-dimensional materials are described in this paper. The materials that are characterized include one-dimensional (1D) carbon nanotubes, and two-dimensional (2D) graphene and boron nitride films. The excellent thermal performance of these materials shows great potential for cooling electronic devices and systems such as in three-dimensional (3D) integrated chip-stacks, power amplifiers, and light-emitting diodes. The thermometers are designed to be serpentine-shaped platinum resistors serving both as hotspots and temperature sensors. By using these thermometers, the thermal performance of the abovementioned emerging low-dimensional materials was evaluated with high accuracy.

The growing use of telecommunication technologies has led the industry to develop infrastructure to support this progress. The outer telecommunications cabinets are part of the Base Transceiver Station (BTS) allowing to accommodate and protect from outer adverse conditions, a set of electronic equipment needed to operate the mobile communication network. This kind of cabinets should have a proper thermal performance to ensure indoor air temperature below 55°C to avoid exceeding the maximum operating temperature of the electronic equipment. This work describes the analysis of the thermal performance of an outdoor telecommunication cabinet (OTC) using the computational tool DesignBuilder. The simulation results are compared to the experimental data collected in real cabinet under normal operating conditions. The simulation results show that the air temperature predicted by the model is closer to the temperature measured experimentally inside the cabinet particularly when the weather data files of the computational model have a similar behavior to the actual weather data. Numerical studies show that the use of mechanical ventilation is effective in the extraction of heat generated inside the cabinet. However, there is a limit beyond which increasing the air flow rate does not result in a significant decrease of the cabinet air temperature. The studies also show the importance of the radiant properties and the geographical location of the cabinet. High values of the outer surface cabinet emissivity impair the thermal performance of the cabinet during the day and for some locations, an operational mechanical ventilation system may not be enough to maintain the indoor air temperature below 55°C. Overall, the use of DesignBuilder proved to be very effective for characterizing the thermal performance of telecommunications outdoor cabinets.

© 2018 Elsevier Ltd The tendency of polymers to shrink upon cooling and to expand upon heating strongly affects polymer processing operations. Therefore, quantifying these properties through dilatometry is crucial. Existing setups to measure dilatometry are, however, mostly limited to solid samples, or are expensive and impractical to use. Moreover, upcoming forms of polymer processing such as additive manufacturing techniques or more commonly named 3D-printing techniques require these properties to be measured under atmospheric pressure, which is not possible with most of the existing setups. Therefore, this paper describes a novel method for pressure-free volumetric dilatometry that is able to characterize samples in both liquid and solid phase, and during liquid-solid transitions. The principle of the method is based on the use of a highly viscous confining fluid that, in combination with a simple piston-die sample container, offers a cheap, easy-to-use and safe method to measure volumetric dilatometry on a variety of samples. The method is verified by comparison with standards and data from literature. ispartof: POLYMER TESTING vol:69 pages:219-224 status: published

DOI: 10.7764/RDLC.17.2.250 The Balearic Islands’ Housing Institute (Instituto Balear de la Vivienda-IBAVI), in collaboration with the Directorate General of Nature, Environmental Education, and Climate Change of the government of the Balearic Islands, has received a European grant worth €754,012 from the LIFE+2012 program to carry out the building and monitoring of 14 public housing units in Sant Ferran, Formentera. The main objective of the project is to contribute to the development of technologies, methods, and innovative instruments in the field of nature conservation, climate change, environmental policy, the production of information, and communication on environmental issues in all EU member states. This paper, a collaborative effort between the University of the Balearic Islands and the IBAVI, presents the results obtained for the determination of the bulk density of a layer of Posidonia oceanica used as an insulating material, and which complied with the limitations of thermal conductivity for a thermal insulation solution in a flat roof.

Experimental work to assess the thermal performance of complex building components often requires testing under real and therefore variable conditions. The PASLINK methodology developed during many years by a European network of outdoor test centres is a dynamic methodology that provides high quality data sets and makes it possible to study the thermal behaviour of tested building components. The test methodology defines the application of a “standard” set of sensors and instruments that are fixed for all experiments carried out in this type of test cells. These minimum set of sensors are the ones described by the PASLINK network quality assurance documentation. The test procedure also includes a calibration process of the test cells. Usually the specific component to be tested is also equipped with extra sensors to obtain specific information of the thermal behaviour of the sample. An example of the sensors over a specific roof test component will be also presented. Finally the data acquisition system requirements will be presented briefly, including both data logger and the software designed for the test control and data acquisition. They must fulfil all the requirements needed for an appropriate testing strategy and a reliable data handling. It is important to note that the requirements here expressed are valid for any type of test carried out to test the thermal behaviour of a building component under real climate but well controlled conditions. Traceability of all processes and data handling is indispensable for guaranteeing a high quality of the experimental work as well as the evaluation of the collected data by means of dynamic analysis methods.

The work presents a new method to evaluate the thermal performance of transparent and semi-transparent materials under real operating conditions. The methodology could be particularly useful to test innovative materials and composites whose thermal properties are not known. It is easily reproducible, low cost, with a low technical impact. The proposed method uses experimental devices named “Solar Test Boxes” (STB) and a dynamic simulation software: IDA Indoor Climate and Energy. The outdoor measurements inside and outside the test boxes are used to accurately calibrate the dynamic simulation model of STB with the objective to obtain the global thermal transmittance (U) and Solar Heat Gain Coefficient (SHGC) of the test sample. The paper illustrates the methodology and the application of the method for the determination of the thermal characteristics of a light diffusing insulating glass. The application of the method to the case study allowed estimating SHGC with accuracy below ±10%. The U-value yields a poor result due to the lack of measurement range (required temperature difference) to assess this parameter.

This paper studies the thermal influence of a light-emitting diode (LED) driver on a retrofit LED lamp, also reporting on a procedure for its thermal characterization and multiscale modeling. In this analysis, temperature is measured by infrared thermography and monitoring specific locations with thermocouples. Experimental results point out that temperature increases considerably in all lamp parts when the driver is installed in the lamp (up to 15% for LED board). The multiscale simulation approach is set with thermal parameters (thermal conductivity, emissivity, and LED board thermal resistance) measured from several parts of the lamp, reaching an agreement between experiment and simulation smaller than 10%. With this model, the driver temperature is investigated under operational conditions accounting for two alternative thermal designs. First, the driver is completely surrounded with a filling material (air completely removed, Case A), and, second, only the thermal contact between the board and the lamp is improved (air is kept, Case B). In both cases, the heat removal from the driver to the ambient by conduction is enhanced, observing that temperature decreases in its most heated components up to 10 °C in Case A, and up to 7 °C in Case B. cop. 1986-2012 IEEE.

Silicone gel is used in power electronics in order to provide a chemical protection and dielectric insulation in insulated gate bipolar transistor (IGBT) power modules. This gel prevents the direct mapping of surface temperature measurements of the component by classical infrared means. The temperature maps inside IGBT modules are usually performed after removal of the silicone gel which does not allow their operation in real environment. In this paper, we explore the ability of thermoreflectance to overcome this limitation in measuring the temperature surface of an IGBT chip through the silicone gel. Thermoreflectance is a non-contact technique, which measures temperature variation through reflectivity variation measurement. Using a “mean” calibration coefficient determinates from optical fiber thermal measurements, thermal images of IGBT modules with and without silicone gel can be compared. Preliminary results indicate that thermoreflectance enables the measurement of surface temperature change on high power IGBT modules with silicone gel and temperature distribution is affected by the presence of the gel.

Gas Engine Heat Pump requires simplified characterization models that allow evaluating its economic and energy impacts. These simplified solutions can be implemented in complex simulation algorithms for different commercial solutions with a low computational cost. The study aims to develop a simplified characterization model highly accurate, easy to reproduce and apply. The methodology carried out uses an experimental installation to analyze different units tested under different operating conditions. With the results of the carried out experimentation, it will be possible to know the real thermal response of these HVAC systems and to develop the simplified characterization model based on operating curves. The thermal behaviour of the systems could be evaluated using the defined curves under any operating condition of the GEHP system. Moreover, they are based on parameters available in the manufacturer datasheets. The results of the validation show that this model is highly accurate. It has a maximum error of 25% and an average error of less than 7%. Also, the formulation shows that it is easy to reproduce and to apply. Last, uncertainty analysis shows reasonable confidence in the identified performance curves. The authors would like to take this opportunity to thank SEDIGAS (the Spanish Gas Association) and manufactured companies (PANASONIC and AISIN) for our fruitful long-term cooperation to promote the deregulation of the market and its role as a critical element in the economic development and quality of life of future generations. Finally, the DACAR project “Zero-Energy Balance Districts Through Algorithms of Adaptive Comfort and Optimal Management of Energy Networks” (BIA2016-77431-C2-2-R) funded by Ministry of Economy and Competitiveness (Government of Spain) and European Regional Development's funds of European Comission (ERDF) for its partial support.

Thermal transient testing is widely used for LED characterization, derivation of compact models, and calibration of 3D finite element models. The traditional analysis of transient thermal measurements yields a thermal model for a single heat source. However, it appears that secondary heat sources are typically present in LED packages and significantly limit the model’s precision. In this paper, we reveal inaccuracies of thermal transient measurements interpretation associated with the secondary heat sources related to the light trapped in an optical encapsulant and phosphor light conversion losses. We show that both have a significant impact on the transient response for mid-power LED packages. We present a novel methodology of a derivation and calibration of thermal models for LEDs with multiple heat sources. It can be applied not only to monochromatic LEDs but particularly also to LEDs with phosphor light conversion. The methodology enables a separate characterization of the primary pn junction thermal power source and the secondary heat sources in an LED package.

In modern phosphor-converted white LEDs, electrical, optical, and thermal performances are inter-twined. It creates challenges for thermal measurements, analysis and thermal compact model development. For example, on one hand, phosphor particles encapsulated in the dome material generate significant amount of heat during blue to white light conversion, and on the other hand, increase dome thermal conductivity. These phenomena limit applicability of single heat flow path and single heat source compact models. The paper presents a comparison of two compact model types for different configurations of a particular mid-power LED. The comparison was done by relating the results of thermal transient analysis of a verified full FEM model with the compact models. The effect of an additional heat flow path corresponding to heat propagation into the LED dome was investigated. Drawbacks and applicability limits of the standard one-dimensional heat flow path interpretation of thermal transient measurements results were shown. A measurement based compact model generation procedure is demonstrated.

The modern white mid-power LEDs usually contain phosphor particles encapsulated in silicone dome material. The particles convert the blue light emitted from the epitaxial layer and play significant role in thermal processes of LED packages. In this paper the influence of the phosphor particles concentration and effect of sedimentation on thermal resistance and junction temperature of mid-power LEDs are investigated. Thermal transient measurements, thermal imaging and finite element simulations are used. It is shown that the sedimentation of phosphor particles has an impact on both thermal resistance and junction temperature of mid- power LEDs. General trends for phosphor particles concentration effect on thermal properties of a mid-power LED are determined.

In this paper PCM is added to three types of stabilized rammed. Mechanical and thermal characterization is carried out. To do so, the compressive strength is optimized and the final compositions obtained are used to formulate the materials which will be thermally characterized. The optimization process is done with a design of experiments (DoE) and a variance analysis (ANOVA). Finally, LCA is used to evaluate the environmental impact during the manufacturing phase, due to the addition of stabilizers and PCM in the rammed earth. The work is partially funded by the Spanish government (ENE2008-06687-C02-01/CON, ENE2011- 28269-C03-01 and ENE2011-28269-C03-02) and the European Union (COST Action TU0802). The authors would like to thank the Catalan Government for the quality accreditation given to their research group GREA (2009 SGR 534) and research group DIOPMA (2009 SGR 645). Lídia Rincón would like to thank the University of Lleida for her research fellowship.

In this paper, a complete thermal characterization (measurement of all static and dynamic thermal parameters) of some selected II-VI binary crystals was carried out. The semiconductors under investigation were grown from the melt by high-pressure/high-temperature modified Bridgman method. The contact photopyroelectric (PPE) method in back configuration (BPPE) and non-contact infrared lock-in thermography technique were used in order to get the thermal diffusivity of the investigated crystals. The thermal effusivity of the samples was obtained by using the PPE technique in the front configuration (FPPE), together with the thermal wave resonator cavity (TWRC) method. Knowing the values of the thermal effusivity and thermal diffusivity, the remaining two thermal parameters, i.e., thermal conductivity and specific heat were calculated.

The present work considers the aero-thermal characterization of a rib-roughened cooling channel for the trailing edge of gas turbine blades, and is based on previous findings from a smooth channel configuration. The passage is characterized by a trapezoidal cross section with high aspect-ratio, radial inlet flow, and coolant discharge at both model tip and trailing side, where seven elongated pedestals are installed. In this study, heat transfer augmentation is achieved by placing inclined squared ribs on the channel central portion. RANS simulations with a SST turbulence model were performed using the commercial solver ANSYS CFX®v14. The numerical tool was first validated on the available experimental data and, subsequently, its capabilities were exploited in a wider range of working conditions, namely at higher rotation speed and different channel orientation. In this way it was possible to highlight the effects that ribs and working conditions have on the development of both flow and thermal fields. The results show that rotation and channel orientation produce contrasting effects. On the rib-roughened wall, rotation/orientation generates an increase/decrease of the heat transfer; conversely, on the trailing side region rotation/orientation has a negative/positive effect on the thermal field.

The paper deals with the cooling of batteries. The first step was the thermal characterization of a single cell of the module, which consists in the detection of the thermal field by means of thermographic tests during electric charging and discharging. The purpose was to identify possible critical hot points and to evaluate the cooling demand during the normal operation of an electric car. After that, a study on the optimal configuration to obtain the flattening of the temperature profile and to avoid hot points was executed. An experimental plant for cooling capacity evaluation of the batteries, using air as cooling fluid, was realized in our laboratory in ENEA Casaccia. The plant is designed to allow testing at different flow rate and temperatures of the cooling air, useful for the assessment of operative thermal limits in different working conditions. Another experimental facility was built to evaluate the thermal behaviour changes with water as cooling fluid. Experimental tests were carried out on the LiFePO4 batteries, under different electric working conditions using the two loops. In the future, different type of batteries will be tested and the influence of various parameters on the heat transfer will be assessed for possible optimal operative solutions.

This paper reports on the thermal characterization, via the thermal conductivity, of natural materials, such as mulch and lava rock and their usefulness as building insulation. Experiments were carried out using a scale one monitored wall (i.e. heat flux and temperature sensors) exposed to a heating source on one side and to an air conditioned space on the other. The wall system was composed of an 8.85 cm thick cavity, where the mulch and lava rock were placed. The cavity was enclosed between two layers of pine wood (40 mm thick each). After the experiments and statistical data manipulation, the estimated thermal conductivity of the materials were 0.48 ± 0.001 W.m-1.K-1 and 0.129 ± 0.003 W.m-1.K-1 for mulch and lava-rock, respectively. That is, mulch has a thermal conductivity comparable to that of bulk hemp while lava rock has a thermal conductivity comparable to that of hemp brick. These values indicate the usefulness of mulch, compared to the impracticality of using lava-rocks materials for building insulation.

In this paper, Silex Microsystems, the world's largest Pure-Play MEMS foundry, together with partners TNO and VTT, present our recent advancements in RF through silicon Vias (TSV) for 3D integrated passive devices (IPD) applications, achieved in conjunction with the European consortium EPAMO. A novel open TSV fabrication process on 200 mm diameter 305 μm thick High Resistivity wafers has been used to demonstrated High Aspect Ratio Through Silicon Vias (HAR TSV), focusing on tight pitch, resulting in 36 TSV/mm2 Via density. 305 μm wafer thickness enables the fabrication of rigid interposers, an advancement in the commercialization of 3D packaging technology. The fabrication includes double sided deep reactive ion etching (DRIE), developments and evaluation on various conformal high aspect ratio (HAR) plating seedlayer processes, and void-free TSV Cu plating of open rigid TSV structures and bonding to glass wafers for characterization. The electrical characterization of the fabricated devices was performed by VTT with excellent measured RF properties: in specific, low RF losses as well as low DC resistances of less than 20 mOhm/TSV. Several different coplanar waveguide (CPW) test vehicles and other RF TSV test structures together with Daisy Chain and parasitic Capacitance test structures were designed, fabricated and evaluated. The loss of a single coplanar TSV transition is less than 0.04 dB @ 5 GHz, which is considered to be very small. The developed TSV technology was also employed to fabricate 3D toroidal inductors. These inductors were characterized by TNO showing high Q-factor (>30) and self-resonance frequency (> 6 GHz) for 3D inductors in the range of 1-15 nH. 1 and 2 port inductor temperature characteristics over temperature interval from room temperature to 111°C are reported. A fabrication integration scheme for fully integrated RF-IPD with 3D TSV based inductors and high ohmic polysilicon (p-Si) resistors and piezoelectric (PZT) metal-insulator-metal (MIM) capacitors are discussed. Outlook for improvements using integrated high frequency magnetic flux materials and commercialization aspects are described. © 2013 IEEE.

The aim of present study is to investigate different methodologies to achieve a better contact between a photovoltaic panel and a thermal plate, in order to cool the PV panel by means of water in the perspective of coupling it with a heat pump. It is believed that this kind of system allows to obtain a higher energy efficiency. The analysis is developed both experimentally and numerically, testing different kinds of configurations in different operating conditions. Simulations are employed to analyze the effect of the variations of the contact resistance between the panel and the thermal plates, demonstrating that the use of a conductive paste increases the overall performance of the panel. Results show interesting possibilities in terms of retrofitting of existing photovoltaic panels by employing very simple solutions, such as to fix the thermal plate on the rear of the panel by means of wood ribs.

In the present study stoichiometric, b-axis oriented La5Ca 9Cu24O41 thin films were grown by pulsed laser deposition on (1 1 0) SrTiO3 substrates in the temperature range 600-750 °C. High resolution transmission electron microscopy was employed to investigate the growth mechanism and the epitaxial relationship between the SrTiO3 substrates and the La5Ca9Cu 24O41 films grown at 700 °C. The 3-ω method was used to measure the cross-plane thermal conductivity of La5Ca 9Cu24O41 films in the temperature range 50-350 K. The observed glass-like behavior is attributed to atomic-scale defects, grain boundaries and an interfacial layer formed between film and substrate. © 2011 Elsevier B.V. All rights reserved. 520 4613 4616 4613-4616

Heat storage or thermal energy storage is one of the key technologies towards an efficient use of renewable energy resources, particulary the thermochemical heat storage looks promising, but the progress has not yet been succeeded. Therefore our research group focuses on the development of a heat storage system called “thermal battery” for private households and industry applications. On the one hand especially thermochemical reactions have a high potential for high energy density and long term storage. On the other hand the used materials in particular hygroscopic salts are related to disadvantages such as agglomeration, storage capacity loss over cycling or slow reaction kinetics. Those disadvantages are caused by deliquescence and by the occurrence of side reactions, among other effects. We combined the optimization of mixing of salt hydrates and impregnation of carriers to overcome these disadvantages. This paper reports on synthesis of thermochemical materials and comparison of the material properties energy density and effective thermal conductivity.

We propose a power-efficient many-core server-on-chip system with 3D-stacked Wide I/O DRAM targeting cloud workloads in datacenters. The integration of 3D-stacked Wide I/O DRAM on top of a logic die increases available memory bandwidth by using dense and fast Through-Silicon Vias (TSVs) instead of off-chip IOs, enabling faster data transfers at much lower energy per bit. We demonstrate a methodology that includes full-system microarchitectural modeling and rapid virtual physical prototyping with emphasis on the thermal analysis. Our findings show that while executing CPU-centric benchmarks (e.g. SPECInt and Dhrystone), the temperature in the server-on-chip (logic+DRAM) is in the range of 175-200°C at a power consumption of less than 20W, exceeding the reliable operating bounds without any cooling solutions, even with embedded cores. However, with real cloud workloads, the power density in the server-on-chip remains much below the temperatures reached by the CPU-centric workloads as a result of much lower power burnt by memory-intensive cloud workloads. We show that such a server-on-chip system is feasible with a low-cost passive heat sink eliminating the need for a high-cost active heat sink with an attached fan, creating an opportunity for overall cost and energy savings in datacenters. © 2012 IEEE. 175 182 Sponsors: IEEE IEEE Circuits and Systems Society IEEE Computer Society Concordia University Ecole de Technologie Superieure (ETS) Conference code: 94819 Cited By :6

International audience; The Lithium-Ion Capacitor (LIC) is a new hybrid energy storage device. Its structure combines the electrical double-layer capacitor (EDLCs) and lithium-ion technology. Its elementary structure is composed of a positive electrode with activated carbon as in double-layer capacitor and a negative electrode based on Li doped carbon similar to the Li-Ion battery. The advantage of the LIC technology compared to the conventional storage device lies in the fact that the power density and the nominal voltage are higher and the energy density is much higher than EDLCs. This paper deals with the electrical and thermal characterization of this new energy storage device. The LIC equivalent series resistance and capacitance are determined based on extended electrical characterization tests. The LIC parameters variations according to the frequency and to the temperature are presented. Finally, the LIC temperature parameters and distribution over the surface area as a function of time is presented and analyzed.

Chip designers place on-chip sensors to measure local temperatures, thus preventing thermal runaway situations in multicore processing architectures. However, thermal characterization is directly dependent on the number of placed sensors, which should be minimized, while guaranteeing full detection of all hot-spots and worst case temperature gradient. In this paper, we present EigenMaps: a new set of algorithms to recover precisely the overall thermal map from a minimal number of sensors and a near-optimal sensor allocation algorithm. The proposed methods are stable with respect to possible temperature sensor calibration inaccuracies, and achieve significant improvements compared to the state-of-the-art. In particular, we estimate an entire thermal map for an industrial 8-core industrial design within 1°C of accuracy with just four sensors. Moreover, when the measurements are corrupted by noise (SNR of 15 dB), we can achieve the same precision only with 16 sensors.

Next-generation High-Performance Computing (HPC) applications need to tackle outstanding computational complexity while meeting latency and Quality-of-Service constraints. Heterogeneous Multi-Processor Systems-on-Chip (MPSoCs), equipped with a mix of general- purpose cores and reconfigurable fabric for custom acceleration of computational blocks, are key in providing the flexibility to meet the requirements of next-generation HPC. However, heterogeneity brings new challenges to efficient chip thermal management. In this context, accurate and fast thermal simulators are becoming crucial to understand and exploit the trade-offs brought by heterogeneous MPSoCs. In this paper, we first thermally characterize a next-generation HPC workload, the online video transcoding application, using a highly- accurate Infra-Red (IR) microscope. Second, we extend the 3D-ICE thermal simulation tool with a new generic heat spreader model capable of accurately reproducing package surface temperature, with an average error of 6.8% for the hot spots of the chip. Our model is used to characterize the thermal behaviour of the online transcoding application when running on a heterogeneous MPSoC. Moreover, by using our detailed thermal system characterization we are able to explore different application mappings as well as the thermal limits of such heterogeneous platforms.