Methods of Technical Prognostics Applicable to Embedded Systems

Hlavní cílem dizertace je poskytnutí uceleného pohledu na problematiku technické prognostiky, která nachází uplatnění v tzv. prediktivní údržbě založené na trvalém monitorování zařízení a odhadu úrovně degradace systému či jeho zbývající životnosti a to zejména v oblasti komplexních zařízení a strojů. V současnosti je technická diagnostika poměrně dobře zmapovaná a reálně nasazená na rozdíl od technické prognostiky, která je stále rozvíjejícím se oborem, který ovšem postrádá větší množství reálných aplikaci a navíc ne všechny metody jsou dostatečně přesné a aplikovatelné pro embedded systémy. Dizertační práce přináší přehled základních metod použitelných pro účely predikce zbývající užitné životnosti, jsou zde popsány metriky pomocí, kterých je možné jednotlivé přístupy porovnávat ať už z pohledu přesnosti, ale také i z pohledu výpočetní náročnosti. Jedno z dizertačních jader tvoří doporučení a postup pro výběr vhodné prognostické metody s ohledem na prognostická kritéria. Dalším dizertačním jádrem je představení tzv. částicového filtrovaní (particle filtering) vhodné pro model-based prognostiku s ověřením jejich implementace a porovnáním. Hlavní dizertační jádro reprezentuje případovou studii pro velmi aktuální téma prognostiky Li-Ion baterii s ohledem na trvalé monitorování. Případová studie demonstruje proces prognostiky založené na modelu a srovnává možné přístupy jednak pro odhad doby před vybitím baterie, ale také sleduje možné vlivy na degradaci baterie. Součástí práce je základní ověření modelu Li-Ion baterie a návrh prognostického procesu.The main aim of the thesis is to provide a comprehensive overview of technical prognosis, which is applied in the condition based maintenance, based on continuous device monitoring and remaining useful life estimation, especially in the field of complex equipment and machinery. Nowadays technical prognosis is still evolving discipline with limited number of real applications and is not so well developed as technical diagnostics, which is fairly well mapped and deployed in real systems. Thesis provides an overview of basic methods applicable for prediction of remaining useful life, metrics, which can help to compare the different approaches both in terms of accuracy and in terms of computational/deployment cost. One of the research cores consists of recommendations and guide for selecting the appropriate forecasting method with regard to the prognostic criteria. Second thesis research core provides description and applicability of particle filtering framework suitable for model-based forecasting. Verification of their implementation and comparison is provided. The main research topic of the thesis provides a case study for a very actual Li-Ion battery health monitoring and prognostics with respect to continuous monitoring. The case study demonstrates the prognostic process based on the model and compares the possible approaches for estimating both the runtime and capacity fade. Proposed methodology is verified on real measured data.

Light-controllable viscoelastic properties of a photolabile carboxybetaine ester-based polymer with mucus and cellulose sulfate

In this study, the interaction of a photoswitchable carboxybetaine ester-based polymer with mucus and cellulose sulfate was elucidated, showing light-controllable viscoelastic properties. This polymer contains photolabile o-nitrobenzyl ester moieties, allowing transformation from its polycationic form to a charge-balanced nontoxic polyzwitterionic form upon photolysis by irradiation at 365 nm. Rheological studies revealed that the polycationic form of the polymer interacts with mucus and cellulose sulfate to create a physically crosslinked hydrogel based primarily on polyionic complexation and partially on hydrogen bonding. In these cases, a dramatic change in the rheological synergism was confirmed for mucus-based and cellulose sulfate-based systems. Rheological synergism with the polycationic carboxybetaine ester sample reached nearly 4 and 3.8, while it decreased with the charge-balanced zwitterionic sample to 0.3 and 0.7 after irradiation of the mucus-based and cellulose sulfate-based systems, respectively. Disruption of the interaction during light-induced transformation was on-line monitored and showed a 3 and 3.3 times decrease in the elastic modulus for the mucus-based and cellulose sulfate-based systems, respectively. These properties suggest possible biomedical applications, such as spatially controlled drug release or laparoscopic utilization.Qatar National Research Fund, QNRF; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Qatar University, QU: 7 - 1724 - 3 - 438, QUUG-CAM-2017-

Electrically conductive, transparent polymeric nanocomposites modified by 2D Ti3C2Tx (MXene)

The electrically conductive, transparent, and flexible self-standing thin nanocomposite films based on copolyamide matrix (coPA:Vestamelt X1010) modified with 2D Ti3C2Tx (MXene) nanosheets were prepared by casting and their electrical, mechanical and optical properties and then, were investigated. The percolation threshold of the MXene filler within the coPA matrix was found to be 0.05 vol. %, and the highest determined electrical conductivity was 1.4 x 10(-2) Scm(-1) for the composite filled with 5 wt. % (1.8 vol. %) of MXene. The electrical conductivity of the as-prepared MXene was 9.1 Scm(-1), and the electrical conductivity of the MAX phase (the precursor for MXene preparation) was 172 Scm(-1). The transparency of the prepared composite films exceeded 75%, even for samples containing 5 wt. % of MXene, as confirmed by UV spectroscopy. The dynamic mechanical analysis confirmed the improved mechanical properties, such as the storage modulus, which improved with the increasing MXene content. Moreover, all the composite films were very flexible and did not break under repeated twisting. The combination of the relatively high electrical conductivity of the composites filled with low filler content, an appropriate transparency, and good mechanical properties make these materials promising for applications in flexible electronics.Qatar University Collaborative High Impact Grant [QUHI-CENG-18/19-1

Piezoresponse, mechanical, and electrical characteristics of synthetic spider silk nanofibers

This work presents electrospun nanofibers from synthetic spider silk protein, and their application as both a mechanical vibration and humidity sensor. Spider silk solution was synthesized from minor ampullate silk protein (MaSp) and then electrospun into nanofibers with a mean diameter of less than 100 nm. Then, mechanical vibrations were detected through piezoelectric characteristics analysis using a piezo force microscope and a dynamic mechanical analyzer with a voltage probe. The piezoelectric coefficient (d33) was determined to be 3.62 pC/N. During humidity sensing, both mechanical and electric resistance properties of spider silk nanofibers were evaluated at varying high-level humidity, beyond a relative humidity of 70%. The mechanical characterizations of the nanofibers show promising results, with Young’s modulus and maximum strain of up to 4.32 MPa and 40.90%, respectively. One more interesting feature is the electric resistivity of the spider silk nanofibers, which were observed to be decaying with humidity over time, showing a cyclic effect in both the absence and presence of humidity due to the cyclic shrinkage/expansion of the protein chains. The synthesized nanocomposite can be useful for further biomedical applications, such as nerve cell regrowth and drug delivery. © 2018 by the authors. Licensee MDPI, Basel, Switzerland.NPRP from the Qatar National Research Fund (Qatar Foundation) [NPRP 7-1724-3-438

Piezoresponse, Mechanical, and Electrical Characteristics of Synthetic Spider Silk Nanofibers

This work presents electrospun nanofibers from synthetic spider silk protein, and their application as both a mechanical vibration and humidity sensor. Spider silk solution was synthesized from minor ampullate silk protein (MaSp) and then electrospun into nanofibers with a mean diameter of less than 100 nm. Then, mechanical vibrations were detected through piezoelectric characteristics analysis using a piezo force microscope and a dynamic mechanical analyzer with a voltage probe. The piezoelectric coefficient (d33) was determined to be 3.62 pC/N. During humidity sensing, both mechanical and electric resistance properties of spider silk nanofibers were evaluated at varying high-level humidity, beyond a relative humidity of 70%. The mechanical characterizations of the nanofibers show promising results, with Young’s modulus and maximum strain of up to 4.32 MPa and 40.90%, respectively. One more interesting feature is the electric resistivity of the spider silk nanofibers, which were observed to be decaying with humidity over time, showing a cyclic effect in both the absence and presence of humidity due to the cyclic shrinkage/expansion of the protein chains. The synthesized nanocomposite can be useful for further biomedical applications, such as nerve cell regrowth and drug delivery

Controllably coated graphene oxide particles with enhanced compatibility with poly(ethylene-co-propylene) thermoplastic elastomer for excellent photo-mechanical actuation capability

This paper reports the utilization of the controllable coating via SI-ATRP technique as a promising approach for controlling stimuli-responsive capabilities of graphene oxide (GO) based nanocomposites. Various polymer brushes with controlled molar mass and narrow dispersity were grown from the surface of GO particles. Modification of GO with poly(methyl methacrylate) and poly(n-butyl methacrylate) was proved by transmission electron microscopy, thermogravimetric analysis with online FTIR recording and finally by X-ray photoelectron spectroscopy (XPS). Densities of GO-based materials were investigated and conductivity measurements showed the increase values. XPS and Raman shift was used to confirm the GO particles reduction. A compatibility of the filler with propylene-based elastomer was elucidated by melt rheology. The light-induced actuation capability was investigated on composite samples to show, that polymer hybrid particles based on GO have better compatibility with the polymer matrix and thus their proper dispersibility was significantly improved. In addition the plasticizing effect of the short polymer grafts present on the GO filler surface has the crucial impact on the matrix stiffness and thus the ability of composite material to reversibly respond to the external light stimulation. © 2020 Elsevier B.V.Qatar University Collaborative High Impact Grant [QUHI-CENG-18/19-1]; Grant Agency of the Czech RepublicGrant Agency of the Czech Republic [16-20361Y]; Ministry of Education, Youth and Sports of the Czech Republic program NPU I [LO1504]; Research & Innovation Operational Programme - ERDF [313021T081]; VEGAVedecka grantova agentura MSVVaS SR a SAV (VEGA) [2/0129/19]; European Regional Development Fund (ERDF)European Union (EU); national budget of Czech Republic [CZ.1.05/2.1.00/19.0409]; National Science Centre, Poland [UMO-2016/23/P/ST5/02131]; European Unions's Horizon 2020 research and innovation programme under Marie Sklodowska-Curie grantEuropean Union (EU) [665778]; Operational Program Research and Development for innovation

Electrically conductive, transparent polymeric nanocomposites modified by 2D Ti3C2Tx (MXene)

The electrically conductive, transparent, and flexible self-standing thin nanocomposite films based on copolyamide matrix (coPA:Vestamelt X1010) modified with 2D Ti3C2Tx (MXene) nanosheets were prepared by casting and their electrical, mechanical and optical properties and then, were investigated. The percolation threshold of the MXene filler within the coPA matrix was found to be 0.05 vol. %, and the highest determined electrical conductivity was 1.4 × 10-2 S·cm-1 for the composite filled with 5 wt. % (1.8 vol. %) of MXene. The electrical conductivity of the asprepared MXene was 9.1 S·cm-1, and the electrical conductivity of the MAX phase (the precursor for MXene preparation) was 172 S·cm-1. The transparency of the prepared composite films exceeded 75%, even for samples containing 5 wt. % of MXene, as confirmed by UV spectroscopy. The dynamic mechanical analysis confirmed the improved mechanical properties, such as the storage modulus, which improved with the increasing MXene content. Moreover, all the composite films were very flexible and did not break under repeated twisting. The combination of the relatively high electrical conductivity of the composites filled with low filler content, an appropriate transparency, and good mechanical properties make these materials promising for applications in flexible electronics.Author Contributions: Conceptualization, I.K. and M.M.; methodology, I.K. and P.S.; software, P.S.; validation, P.S. A.T.; formal analysis, P.S., Z.S., M.M, and Ma.M.; investigation, A.T., P.S., M.M., Ma.M., J.P. and A.P.; resources, I.K.; data curation, P.S., J.P., I.K., Ma.M., and M.M.; writing—original draft preparation, A.T., P.S., M.M. and Z.S.; writing—review and editing, I.K., M.M. and P.S.; visualization, P.S., J.P. and A.P.; supervision, I.K.; project administration, I.K.; funding acquisition, I.K.; Funding: This publication was supported by Qatar University Collaborative High Impact Grant QUHI-CENG-18/19-1. The findings achieved herein are solely the responsibility of the authors

Anti-corrosive and oil sensitive coatings based on epoxy/polyaniline/magnetite-clay composites through diazonium interfacial chemistry

Epoxy polymer nanocomposites filled with magnetite (Fe3O4) clay (B), named (B-DPA-PANI@Fe3O4) have been prepared at different filler loading (0.1, 0.5, 1, 3, 5 wt. %). The surface modification of clay by polyaniline (PANI) is achieved in the presence of 4-diphenylamine diazonium salt (DPA). The effects of the nanofiller loading on Tensile, mechanical and dielectric properties were systematically studied. Improved properties was highlighted for all reinforced samples. The addition of only 3 wt. % of the filler enhanced the tensile strength of the composites by 256%, and the glass transition temperature Tg by 37%. The dielectric spectra over a broad frequency showed a robust interface between the hybrid (B-DPA-PANI@Fe3O4) fillers and epoxy matrix. The results showed most significant improvement in corrosion inhibition using electrochemical impedance spectroscopy (EIS) in 3.5 wt % NaCl, as well as a significant response in oil sensing test. High charge transfer resistance of 110 × 106 Ω.cm2 using 3-wt % of filler was noted compared to 0.35 × 106 Ω.cm2 for the pure epoxy. The results obtained herein will open new routes for the preparation of efficient anticorrosion sensor coatings. © 2018, The Author(s).NPRP Award from the Qatar National Research Fund (a member of Qatar Foundation) [8-878-1-172

Foamed phase change materials based on recycled polyethylene/paraffin wax blends

Foamed phase-change materials (FPCMs) were prepared using recycled linear low-density polyethylene (LLDPE) blended with 30 wt.% of paraffin wax (PW) and foamed by 1,1 '-azobiscarbamide. The protection of pores' collapse during foaming process was insured through chemical cross-linking by organic peroxide prior foaming. This work represents one of very few attempts for a preparation of polymeric phase change foams without a use of micro-encapsulated phase change component leading to the enhancement of the real PCM component (PW) within a final product. The porous structure of fabricated foams was analyzed using micro-computed tomography, and direct observation, and reconstruction of the internal structure was investigated. The porosity of FPCMs was about 85-87 vol.% and resulting thermal conductivity 0.054-0.086 W/m center dot K. Differential Scanning Calorimetry was used to determine the specific enthalpies of melting (22.4-25.1 J/g) what is the latent heat of materials utilized during a heat absorption. A stability of samples during 10 heating/cooling cycles was demonstrated. The phase change changes were also investigated using the dynamic mechanical analysis from 0 degrees to 65 degrees C during the 10 cycles, and the mechanical stability of the system and phase-change transition were clearly confirmed, as proved by DSC. Leaching test revealed a long-term release of PW (around 7% of its original content) from samples which were long term stored at temperatures over PW melting point. This is the usual problem concerning polymer/wax blends. The most common, industrially feasible solution is a lamination of products, for instance by aluminum foils. Finally, the measurement of the heat flow simulating the real conditions shows that samples containing PW decrease the energy passing through the sample from 68.56 to 34.88 kJ center dot m(-2). In this respect, FPCMs provide very effective double functionality, firstly common thermal insulators, and second, as the heat absorbers acting through melting of the PW and absorbing the excessive thermal energy during melting. This improves the heat protection of buildings and reduces temperature fluctuations within indoor spaces.Qatar National Research Fund (A Member of the Qatar Foundation) [13S-0127-200177]; Ministry of Education, Youth and Sports of the Czech Republic-DKRVO [RP/CPS/2020/003

Foamy phase change materials based on linear low-density polyethylene and paraffin wax blends

Foamy phase-change materials (FPCMs) based on linear low-density polyethylene (LLDPE) blended with 30 wt.% of paraffin wax (W) were successfully prepared for the first time. The advantage of these materials is their double functionality. First, they serve as standard thermal insulators, and second, the paraffin wax acts as a phase change component that absorbs thermal energy (the latent heat) during melting if the temperature increases above its melting point, which ensures better heat protection of buildings, for instance, against overheating. The density of the porous fabricated FPCM was 0.2898 g/cm(3) with pore content 69 vol.% and gel portion achieved 27.5 wt.%. The thermal conductivity of the LLDPE/W foam was 0.09 W/m.K, whereas the thermal conductivity of the neat LLDPE foam prepared under the same conditions was 0.06 W/m.K, which caused a higher porosity of approximately 92 vol.%. The FPCM absorbed or released approximately 22-23 J/g during melting or cooling, respectively, and the material was stable under thermal and mechanical cycling.Qatar Foundation, QF; Qatar National Research Fund, QNR