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PublicationGenerative Machine Learning for Resource-Aware 5G and IoT SystemsExtrapolations predict that the sheer number of Internet-of-Things (IoT) devices will exceed 40 billion in the next five years. Hand-crafting specialized energy models and monitoring sub-systems for each type of device is error prone, costly, and sometimes infeasible. In order to detect abnormal or faulty behavior as well as inefficient resource usage autonomously, it is of tremendous importance to endow upcoming IoT and 5G devices with sufficient intelligence to deduce an energy model from their own resource usage data. Such models can in-turn be applied to predict upcoming resource consumption and to detect system behavior that deviates from normal states. To this end, we investigate a special class of undirected probabilistic graphical model, the so-called integer Markov random fields (IntMRF). On the one hand, this model learns a full generative probability distribution over all possible states of the system-allowing us to predict system states and to measure the probability of observed states. On the other hand, IntMRFs are themselves designed to consume as less resources as possible-e.g., faithful modelling of systems with an exponentially large number of states, by using only 8-bit unsigned integer arithmetic and less than 16KB memory. We explain how IntMRFs can be applied to model the resource consumption and the system behavior of an IoT device and a 5G core network component, both under various workloads. Our results suggest, that the machine learning model can represent important characteristics of our two test systems and deliver reasonable predictions of the power consumption.
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PublicationSmart sensor systems for extremely harsh environments( 2021)Sensors systems are key elements for capturing environmental properties and are increasingly important in industry 4.0 for the intelligent control of processes. However, under harsh operating conditions like high temperatures, high mechanic load or aggressive environments, standard electronics cannot be used. Eight Fraunhofer institutes have therefore bundled their competencies in sensors, microelectronics, assembly, board design, laser applications and reliability analysis to establish a technology platform for sensor systems working under extreme conditions.
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PublicationExperimental Demonstration of Temperature Sensing with Packaged Glass Bottle Microresonators( 2018)Whispering gallery mode (WGM) glass bottle microresonators are potential highly sensitive structures for a variety of physical and bio-chemical sensing applications. In this paper, we experimentally demonstrate the practical use of glass bottle resonators as temperature sensors. The basic parameters, such as WGM resonance wavelengths, free spectral ranges, and Q factors, have been investigated by coupling light from a tapered fiber to the bottle structure. We show the spectral characteristics of the WGMs by choosing different bottle dimensions and taper diameters. For practical measurements, a robust 3D-printed package that includes the bottle resonator and the tapered fiber has been proposed. The packaged bottle has a central diameter Dc = 207 µm and a length L = 300 µm. Temperature sensing experiments were also performed. A linear response of the WGM shifts as a function of the temperature is confirmed. The fitted experimental data indicate a temperature sensitivity of 10.5 pm/K at l ~ 1550 nm, resulting in a limit of detection of 0.06 K. These values can be compared with values reported for other WGM resonators. Additionally, bottle resonators are made with simple splicing methods and their assembly method can be easily defined due to large coupling tolerances.
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PublicationEnergy harvesting and conversion - applications of piezoelectric transformer and transducer MEMS( 2018)A systematic investigation of the feasibility to integrate complete piezo-based power supply on silicon was done. Up to now, fully integrated off-line power supplies on chip are available as products for below 1 Watts. Higher power levels up to 10 Watts and more are strongly desired for many miniaturized applications as Off-Line LED light sources, integrated power supplies for communication devices as iPhone, portable devices for medical applications, portable beamers an others. The integration of high-efficient power supplies based on magnetic transformers (PT) including galvanic isolation is limited due to the physics of electromagnetism. Piezoelectric transformers can be integrated as MEMS when PZT material is applied on silicon to a height of several Micrometers to form an oscillating device which will be processed after micro-bonding in an etching process. Although power density of discrete PT is already high, it can be increased by a factor of 100 to 1000 in integrated devices on silicon taking advantage of uniform crystal structure of sputtering process and improved heat removal through silicon. Serial piezo-transformer-strings allow for high isolating voltage up to 4 kV and provide efficiency up to 95% or more, but unfortunately on the cost of significant large chip area. However, piezoelectric transformers will gain higher acceptance in power converters if a magnetic-field-free environment is requested as for magnetic resonance tomography. Promising piezoelectric applications can be found for transformer-transducer units to harvest ultrasonic energy, preferably in medical therapy-diagnosis applications, but further, in industrial autonomous sensor supplies with avoidance of electromagnetic disturbance. Piezoelectric energy harvesting becomes attractive using ultrasonic energy harvester MEMS with wide range frequency excitation using permanent magnet cantilever construction. Ultrasonic MEMS loudspeakers are miniaturized alternatives to traditional magnetic devices. The advantage of piezoelectric MEMS applications will result in an extreme miniaturization compared to conventional power conversion by magnetic or electrostatic solutions. High reliability including intelligent integrated functions in some cases may improve the practicability of piezoelectric MEMS.
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PublicationMiniaturization of power converters by piezoelectric transformers - chances and challenges( 2017)A systematic approach of the feasibility to integrate complete piezo-based power supply on silicon is the focus of research activities within Fraunhofer EAS, ISIT an IZM. Up to now, fully integrated off-line power supplies on chip are available for below 1 Watts, e.g. from Texas Instruments. Higher power levels up to 10 Watts and more are strongly desired for many miniaturized applications as Off-Line LED light sources, integrated power supplies for communication devices as iPhone, portable devices for medical applications, portable beamers an others. The integration of high-efficient power supplies based on magnetic transformers (PT) including galvanic isolation is limited due to the physics of electromagnetism. Piezoelectric transformers can be integrated when PZT material is applied on silicon to a height of several Micrometers to form an oscillating device which will be processed after micro-bonding in an etching process. Although power density of discrete PT is already high, it can be increased by a factor of 100 to 1000 in integrated devices on silicon taking advantage of uniform crystal structure of sputtering process and improved heat removal through silicon. The driving topology can be formed by high-voltage Mosfets or multi-level low-voltage Mosfet topology based on SOI or GaN on Si and integrated micro-inductors in the future. Serial piezo-transformer-strings allow for high isolating voltage up to 4 kV and provide efficiency up to 95% or more. Synchronous rectifying devices can be formed by low-voltage Mosfets at the output stage of the power supply. The advantage will be an extreme miniaturization compared to discrete power supplies, reduction of blocking capacitors by interleaving techniques, and thus, high reliability including intelligent integrated functions as stabilization circuits, sensors or control.
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PublicationWie nachhaltig ist das Fairphone 2? - Ergebnisse einer Expertenbefragung(Fraunhofer IZM, 2016)Das niederländische Unternehmen Fairphone B.V. hat mit dem Fairphone 2 sein zweites Smartphone auf den Markt gebracht, bei dessen Produktion und Gestaltung explizit auf Nachhaltigkeit gesetzt wurde. Insbesondere sollen in der Zulieferkette dort Veränderungen angestoßen werden, wo in der Vergangenheit die Elektronikbranche erheblich in der Kritik stand, so bei den Arbeitsbedingungen in der Fertigung und der Gewinnung der Rohstoffe. Das Fraunhofer IZM und die Deutsche Umwelthilfe führten im Auftrag der Deutschen Telekom eine Expertenumfrage zum Thema Wie nachhaltig ist das Fairphone 2? durch. Die Umfrage adressiert die Aspekte verantwortlicher Rohstoffabbau, faire Arbeitsbedingungen, nachhaltiges Design, Lebenszyklus und Transparenz.
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PublicationEntwurfsmethoden für verbesserte robuste Batteriemanagementsysteme. Teilvorhaben(Fraunhofer IIS / EAS, 2016)
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PublicationMethodology guidance - energy profiles and carbon footprint data for passive components and connectors(Fraunhofer IZM, 2015)Requests for environmental component data are passed through the supply chain and component manufacturers face the growing need to serve these inquiries. Whereas the passive components industry learned to handle material declaration requests by developing Umbrella Specifications, the field of CO2 or energy profiles lacks harmonization and clear and credible guidance, how to compile such datasets. There are several thousand different types of passive electronic components and it is neither feasible to compile and maintain datasets for all of them, nor would such level of detail be of much added value for carbon footprint calculations given the general uncertainties of such assessments. An abridged and harmonized model is required and to follow with such a model the approach of the material Umbrella Specifications might lead to an efficient, transparent and manageable solution. The objectives of this guidance document are to reduce the data intensity of environmental assessments for passive components, including connectors.
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PublicationDisassembly analysis of slates: Design for repair and recycling evaluation. Final report(Fraunhofer IZM, 2014)This project was initiated by Fraunhofer IZM, Berlin, to investigate the current status of slate designs with respect to repair and recycling. Following the Energy Star definition, slate computing devices are defined as a type of computer lacking a physical keyboard, relying solely on touchscreen input, having solely a wireless network connection (e.g., Wi-Fi, 3G), and primarily powered from an internal battery (with connection to the mains for charging, not primary powering of the device). EPEAT supported this project. An overarching objective upon request by EPEAT is to create an independent evidence base for future stakeholder discussions on EPEAT criteria for slates. It is not the objective of this study to propose such criteria, nor did the study take into account all facets to def ine such criteria. Definitely, additional aspects and arguments need to be considered thoroughly in the course of the upcoming stakeholder process.
