Analytic modeling of a high temperature thermoelectric module for wireless sensors

A novel high temperature thermoelectric module with thermoelectric materials never before combined in a module is currently researched. The module placement in the cooling channels of a jet engine where the cold side will be cooled by high flow cooling air (550 degrees C) and the hot side will be at the wall (800 degrees C). The aim of the project is to drastically reduce the length of the wires by replacing wired sensors with wireless sensors and power these (3-10mW) with thermoelectric harvesters. To optimize the design for the temperature range and the environment an analytic model was constructed. Using known models for this purpose was not possible for this project, as many of the models have too many assumptions, e.g. that the temperature gradient is relatively low, that thick electrodes with very low resistance can be used, that the heat transfer through the base plates are perfect or that the aim of the design is to maximize the efficiency. The analytical model in this paper is a combination of several known models with the aim to examine what materials to use in this specific environment to achieve the highest possible specific power (mW/g)

Approximate non-linear model predictive control with safety-augmented neural networks

Model predictive control (MPC) achieves stability and constraint satisfaction for general nonlinear systems, but requires computationally expensive online optimization. This paper studies approximations of such MPC controllers via neural networks (NNs) to achieve fast online evaluation. We propose safety augmentation that yields deterministic guarantees for convergence and constraint satisfaction despite approximation inaccuracies. We approximate the entire input sequence of the MPC with NNs, which allows us to verify online if it is a feasible solution to the MPC problem. We replace the NN solution by a safe candidate based on standard MPC techniques whenever it is infeasible or has worse cost. Our method requires a single evaluation of the NN and forward integration of the input sequence online, which is fast to compute on resource-constrained systems. The proposed control framework is illustrated on three non-linear MPC benchmarks of different complexity, demonstrating computational speedups orders of magnitudes higher than online optimization. In the examples, we achieve deterministic safety through the safety-augmented NNs, where naive NN implementation fails

Modelling and experimental verification of more efficient power harvesting by coupled piezoelectric cantilevers

A new piezoelectric energy harvester design is proposed in order to achieve a wider bandwidth without compromising energy conversion efficiency. By coupling two cantilevers where the tip of the bottom one is attached to the base of the upper one, the simulated harvester will have a wider bandwidth and higher power output compared with two simulated single tuned single cantilevers. This is a compact design, using only half the area compared to two parallel single cantilevers at the price of a small increase in height. The measured coupled harvester has approximately 1.7 times higher energy output than the combination of two measured tuned single cantilevers achieved by a coupling with less mechanical damping. With an improved coupling the power output is increased to 2.3 times higher than two single tuned cantilevers

Simulation of a Novel Bridge MEMS-PZT Energy Harvester for Tire Pressure System

Self-powering is becoming an important issue for autonomous sensor systems. By having an on-the-go power source the life span increases in comparison to a limited battery source. In this paper, simulation of an innovative design for a piezoelectric energy harvester for Tire Pressure Measurement System (TPMS) is presented. The MEMS-based thin-film PZT harvester structure is in the form of a bridge with a big central seismic mass and multiple electrodes. This design takes the advantage of the S-profile bending and a short beam length to concentrate the piezoelectric effect in a small segment along the beam and maximize the power output for a given displacement. From simulation in Comsol Multiphysics, the 9mm x 5mm bridge, seismic mass of 8.7mg and resonance frequency of 615Hz, generates 1 mu W by mechanical pulses excitation equivalent to driving at 60 km/h (roughly 180G)

Generating stable molecules using imitation and reinforcement learning

Chemical space is routinely explored by machine learning methods to discover interesting molecules, before time-consuming experimental synthesizing is attempted. However, these methods often rely on a graph representation, ignoring 3D information necessary for determining the stability of the molecules. We propose a reinforcement learning (RL) approach for generating molecules in Cartesian coordinates allowing for quantum chemical prediction of the stability. To improve sample-efficiency we learn basic chemical rules from imitation learning (IL) on the GDB-11 database to create an initial model applicable for all stoichiometries. We then deploy multiple copies of the model conditioned on a specific stoichiometry in a RL setting. The models correctly identify low energy molecules in the database and produce novel isomers not found in the training set. Finally, we apply the model to larger molecules to show how RL further refines the IL model in domains far from the training data

Фторидная технология получения титановых порошков

Обоснована необходимость разработки новой технологии переработки титансодержащих концентратов. Выполнено исследование процесса фторирования рутилового концентрата элементным фтором. Описаны процессы, протекающие при электролитическом получении титановых порошков во фторидных расплавах TiF4. Для отмывки от примесей катодного осадка предложено две технологии – в смеси неорганических кислот и безводным HF; показаны преимущества отмывки HF; содержание примесей в порошке титана, полученном отмывкой в безводном HF несколько ниже, чем при "кислотной" отмывке. При промышленном осуществлении процесса HF рециркулирует в схеме, обеспечивая экологическую безопасность и низкую себестоимость Ti.The brief review of industrial technologies of processing the titanium containing concentrates has been carried out. The research of the fluorination process of rutile concentrates with element fluorine was carried out. The processes occurring during the electrolysis of titanic powders from fluoride fusions, from TiF4, are described. In order to wash off impurities of cathode deposit, two techniques were proposed - in a mixture of inorganic acids and anhydrous HF; advantages of washing off with HF are shown; the impurity content in the titanium powder obtained by washing off in anhydrous HF is slightly lower than at "acid" washing off. In the industrial process implementation HF recycles tin a circuit that ensures environmental safety of production and low production cost of obtained Ti

Favorable impact of long-term exercise on disease symptoms in pediatric patients with inflammatory bowel disease

Evidence is growing that both short- and long-term physical exercise have the potential to positively impact on the physiological system related to inflammatory indices, though, such patterns are unknown for pediatric patients with Inflammatory Bowel Disease (IBD). The aim of the present intervention study was to investigate the influence of a single bout and chronic moderate-intensity exercise on IBD-related inflammatory indices and exercise capacity among pediatric individuals with IBD and healthy controls.; Twenty-one pediatric patients with IBD, split into a "remission-group" (IBD-RE; n = 14) and an "active disease group" (IBD-AD; n = 7), were compared to 23 age matched healthy controls (HC). All participants completed a single bout of exercise at baseline and an 8-week exercise intervention. Before and after the single bout of exercise IBD-related inflammatory indices (erythrocyte sedimentation rate (ESR), albumin, C-reactive protein (CRP), cortisol, hemoglobin, hematocrit, thrombocytes and leukocytes) were assessed.; At baseline, after a single bout of exercise, inflammation (albumin, hemoglobin, erythrocytes, hematocrit and leukocytes) increased in all three groups IBD-AD, IBD-RE and HC. CRP and thrombocytes were only elevated in IBD-AD and IBD-RE, compared to HC. After a longer-term exercise intervention, ESR, CRP and thrombocytes significantly decreased in all groups. The longer-term exercise intervention did not decrease acute immunopathologic responses after a single bout of exercise, compared to baseline.; Whereas a single bout of exercise increases albumin, erythrocytes and leukocytes, longer-term moderate-intensity exercise reduced inflammatory markers in pediatric patients with IBD. Children and teenagers with IBD should be encouraged to engage in regular moderate-intensity exercise activities, as such activities may contribute to inflammation suppression and improved disease management

Разработка технологии изготовления детали «Седло»

Выпускная квалификационная работа включает в себя проектирование технологического процесса обработки детали "Седло" и содержит: анализ чертежа и технологичности детали; способ получения заготовки; расчет припусков на обработку; разработку технологического процесса, выбор и расчет режимов резания; размерный анализ технологического процесса.Final qualifying work includes the design of the technological process of processing details in the "Saddle" and contains: an analysis of drawing and technology details; method of harvesting; calculation of allowances for processing; the design process, the selection and calculation of cutting conditions; dimensional analysis process

Detection of mostly viral pathogens and high proportion of antibiotic treatment initiation in hospitalised children with community-acquired pneumonia in Switzerland – baseline findings from the first two years of the KIDS-STEP trial

AIMS OF THE STUDY: Globally, since the introduction of conjugate-vaccines against encapsulated bacteria, respiratory viruses have caused most hospitalisations for community-acquired pneumonia. The aim of this study was to describe pathogens detected and their association with clinical findings in Switzerland. METHODS: Baseline data were analysed for all trial participants enrolled between September 2018 and September 2020 into the KIDS-STEP Trial, a randomised controlled superiority trial on the effect of betamethasone on clinical stabilisation of children admitted with community-acquired pneumonia. Data included clinical presentation, antibiotic use and results of pathogen detection. In addition to routine sampling, nasopharyngeal specimens were analysed for respiratory pathogens using a panel polymerase chain reaction test covering 18 viral and 4 bacterial pathogens. RESULTS: 138 children with a median age of 3 years were enrolled at the eight trial sites. Fever (obligatory for enrolment) had been present for median 5 days before admission. Most common symptoms were reduced activity (129, 93.5%) and reduced oral intake (108, 78.3%). Oxygen saturation <92% was found in 43 (31.2%). Forty-three participants (29.0%) were already on antibiotic treatment prior to admission and 104 participants (75.4%) received antibiotic treatment on admission. Pathogen testing results were available from 132 children: 31 (23.5%) had respiratory syncytial virus detected, 21 (15.9%) human metapneumovirus. The pathogens detected showed expected seasonal and age preponderance and were not associated with chest X-ray findings. CONCLUSIONS: In the context of the predominantly viral pathogens detected, the majority of antibiotic treatment is probably unnecessary. The ongoing trial, as well as other studies, will be able to provide comparative pathogen detection data to compare pre- and post-COVID-19-pandemic settings