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Humidity is a key factor affecting proton exchange membrane fuel cell (PEMFC) efficiency and output performance. Different working conditions have different requirements for humidity. Improper humidity may cause too high or too low water content inside the PEMFC, which will damage the output performance and even shorten the remaining useful life of PEMFC. Therefore, how to control humidity appropriately is a crucial subject. This paper establishes a PEMFC internal water management and inlet humidity model, and the influence of the change of anode inlet humidity on the performance of the PEMFC and the water content of the membrane is analyzed through computational fluid dynamics (CFD) simulation. And the direct control of the inlet humidity, which is difficult to be accurately measured, is converted to the temperature control of the bubble humidifier according to the proposed model, and a back propagation neural network proportion integration differentiation (BPPID) controller is proposed, which combines artificial neural network and digital PID control to adjust PID parameters in real time. The controller is applied to the temperature control of the bubble humidifier and compared with the traditional PID controller and the fuzzy PID controller. It is found that the performance of the BPPID controller is better through the comparison with the experimental results and the stabilization time it takes is only about 50% of that of other controllers.

There is a need to develop upgraded insulant which offers superior dielectric properties than mineral oil in terms of cooling, insulation, and efficient functioning under extreme weather conditions. These oils are nanofluids that are synthesized by dispersing nanoparticles in the oil. These fluids are tested with their ability to withstand various faults under operating conditions by determining the dielectric and electrical properties like ac breakdown strength, relative permittivity, and dielectric dissipation factor. A comparison between nanoparticles and their effect on insulating oils has been widely discussed and presented. In this study, three nanoparticles namely Fe3O4, TiO2, and Fe-Cu are dispersed in three different types of oils namely mineral oil (i.e., transformer oil used as insulating liquid in transformers), synthetic ester oil (i.e., pentaerythritol ester), and rapeseed oil (natural-ester transformer fluid). These nanofluids are considered upgraded insulant due to its superior insulation characteristics compared to pure mineral oil. Synthetic ester-based oils and natural rapeseed oil are tested for insulation capabilities for better results, which show they have all the potential to replace transformer oil in high voltage equipment’s.

This work deals with the electromagnetic characterization of Carasau bread doughs, in the microwave range region. The microstructure, texture, product quality, and dielectric properties were investigated, jointly with a thorough thermogravimetric analysis. The goal is to link the physical properties with the product quality and to process variables. The variation of the dielectric properties during the dough leavening is studied. The dielectric properties of raw materials (water, yeast, salt, and semolina) were measured from 500 MHz to 8.5 GHz. Given the heterogeneous character of bread microstructure, the possibility of predicting by using mixing formula the final characteristic of a standard Carasau bread dough, manufactured with three different semolina wheat batches, is investigated. A power-law model can predict the average dough properties for frequencies higher than 2.45 GHz. This work proposes a dielectric spectroscopy model for this food material. A third-order Cole-Cole model can describe the dielectric spectra of the Carasau doughs over the entire frequency range. The decrease of the complex permittivity of the dough during leavening can be modeled with a reduction of the static permittivity and a decrement of the electrical conductivity. This study can foster the development of a microwave inline system for leavening monitoring.

International audience; The main part of recycling processes are carried out in chemical engineering reactors that involve multiphase flows with dense dispersed phase. In a study and modeling approach of these processes, the description and characterization of hydrodynamic phenomena is crucial. A variety of techniques allows us to realize this type of measurement, but the most used one is the direct imaging associated with an efficient image processing. Recently, deep learning algorithms have proven to be very effective in solving image based problems, which led to the use of these algorithms to extract critical information in chemical engineering apprentices. The method employed in this paper relies on a deep learning based algorithm dedicated to the prediction of 3D features of multiphase flows using 2D projected images. The performance of the method has been evaluated both on synthetic images and on real images of beads in a dispersed phase.

Rapid advancements in information processing and embedded systems require high selective and fast sensors. Conventional gas sensors are not suitable for the detection of isomers of organic compounds due to cross-sensitivity and the response time being limited by slow chemical kinetics. Amperometric gas sensors using conducting polymers modified with metal catalysts are a suitable and robust system due to many tunable properties. In this paper, conducting polymer polyaniline was electrochemically decorated with clusters containing precisely defined number of gold atoms to function as an electro-catalyst. The modified polymer composite showed fast reaction rate for the electro-oxidation of alcohols in both liquid and gas phases. The number of gold atoms affected the catalytic activity. Cyclic voltammograms were measured and results showed discriminable patterns between n-propanol and iso-propanol even at different gas concentrations. Thus, it was demonstrated that gas sensor arrays can be realized by decorating different number of gold atoms on polyaniline electrodes, to yield defined and different selectivity.

SF6 adsorbents absorb many toxic SF6 decomposition products, such as SOF2, SO2F2, and H2S. Ex-service SF6 adsorbents that did not undergo environmentally friendly processing will seriously harm the environment. In this work, thermogravimetric analysis and Fourier transform infrared spectroscopy were used to investigate the adsorbates of ex-service SF6 adsorbents. Adsorbent recycling based on the thermal method was also studied. The vacuum thermal method increased the recycling efficiency of ex-service SF6 adsorbents to 85%-90%. In addition, the adsorbents recovered through thermal method could be reused in SF6-gas-insulated equipment. Considering their influence on equipment operation and maintenance, a harmless treatment technology for ex-service SF6 adsorbents with Ca(OH)2 was proposed. The adsorption and desorption behaviors of SF6 adsorbents were predicted via destiny functional theory. The best treatment effect could be obtained when the Ca(OH)2 amount was equal to 20% of the treatment weight of the adsorbents, and the treatment temperature was maintained at 90 °C. The economic feasibility of the harmless treatment for ex-service SF6 adsorbents with Ca(OH)2 was higher than that of the thermal method.

Non-thermal plasma is an alternative technology of exploiting biomass for efficient production of value added energy carriers. In this study, plasma catalytic liquefaction (PCL) system is successfully developed to achieve rapid and efficient liquefaction of sawdust in the presence of co-solvent polyethylene glycol 200 (PEG 200) and glycerin as well as the acid catalyst H2SO4. The influences of different operating factors such as the catalyst concentration, reaction time, molar ratio of PEG 200 and glycerin and the power supply are investigated in terms of the liquefaction yield and solution temperature, while the roles of the applied voltage and the duty cycle of power supply in the PCL process are discussed in detail. Experimental results show that the sawdust could be completely liquefied into crude bio-oil with a high heating value (HHV) of 19.18 MJ/kg in the mixture containing sawdust and solvent in a ratio of 1/7, and 1 wt.% catalyst H2SO4. Increasing the applied voltage and duty cycle are more efficient giving higher yield of liquid products. Based on the analysis of the processing conditions, suggested that the enhanced performance of the PCL process is linked to the superiority of heating that induced by electric field and the presence of quantities reactive species during the plasma discharge. The physiochemical characteristics of the biomass sample and the liquefied products are interpreted by using elemental analysis, thermogravimetric analysis, Fourier transform infrared spectroscopy (FTIR) and the identities and concentration of the liquid products are determined by gas chromatography-mass spectrometry (GC-MS).

OBJECTIVE: Superparamagnetic Iron Oxide Nanoparticles (SPIONs) are widely researched as contrast agents in clinical magnetic resonance imaging (MRI). SPIONs are frequently coated with anti-biofouling substances such as poly(ethylene glycol) (PEG) to prevent protein deposition and improve circulation time in vivo. However, few previous studies have comprehensively examined optimization of SPION MR properties with respect to physicochemical properties of the core SPION and the polymeric coating. The aim of this study is to determine effects of different methods of chemical attachment of a polymer, polymer chain length, and polymer coating density on the MR relaxivities of SPIONs, thereby contributing to a better understanding of the interaction of these parameters and the efficacy of the designed agent. RESULTS: These studies indicate that the chemical composition and, in particular, the hydrophobicity/hydrophilicity of the chemical group linking PEG chains to a SPION core may play a larger role in the resulting MR relaxivities than other variable properties such as SPION core size and PEG chain length. CONCLUSIONS: The method of SPION fabrication and chemical composition of the coating play a significant role in the MR relaxivities of the resulting particles. These results should be considered in the fabrication of particles for clinical purposes, particularly when optimization of the MR relaxivities is desired.

In this work, wearable resistive gas sensors based on hybrid graphene/zinc oxide (ZnO) nanocomposites were fabricated on a flexible cotton fabric and employed to monitor odorless and colorless carbon monoxide (CO). Dip-coating and chemical bath deposition (CBD) was used to deposit the graphene layer and grow the ZnO nanorods, respectively. The films were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-Ray diffraction (XRD) to investigate their morphological structures, elemental composition, and crystal phase, respectively. Those characterizations were also confirming the growth of ZnO nanorods on the already-deposited graphene layer on fabrics. From the gas sensor measurements at room temperature, it was revealed that these graphene/ZnO nanocomposites were highly sensitive and selective towards CO gas at low concentration down to 10 ppm. The shortest response and recovery times of the sensors were measured to be 280 s and 45 s, respectively. Moreover, in comparison to bare graphene sensors, the surface modification by ZnO nanorods could obviously enhance the sensing response by up to 40% (i.e., doubled sensitivity). These flexible hybrid sensors are therefore expected to be a promising alternative for the existing rigid CO sensors in the market by offering unique nanostructures, low-cost fabrication, high flexibility, and good sensing performances.

The hydrothermal synthesized process was utilized to prepare the CuO nanoparticles, the crystal structure and grain size was determined using XRD. The CuO nanoparticles were subjected to low temperature Plasma. The dielectric studies of plasma treated CuO nanoparticles were investigated with the range of frequency between 50Hz and 5MHz at room temperature. The surface properties of nanoparticles were enhanced by plasma exposure and they became hydrophilic rather than hydrophobic, allowing them to absorb moisture and attain high permittivity than untreated CuO nanoparticles.

Low cost, efficient and Vis-active materials have to be developed and implemented at industrial scale because water re-use is the nowadays priority. The composites with metal oxide matrix and graphene derivative(s) fillers were proved to be viable in photocatalytic processes. Titanium dioxide and reduced graphene oxide can develop Vis-active photocatalytic composites and the interfaces must be optimized targeting efficiency and stability in the aqueous environment. This paper discusses the photocatalytic properties of TiO 2 - rGO composite thin films, the efficiencies in degrading the methylene blue standard pollutant, the effect of the filler concentration and the stability of the composites during the photo-degradation processes.

5-μm Al films are bonded to β-Ga 2 O 3 (−201) substrates using surface activated bonding. The nanostructural properties of as-bonded interfaces are examined using transmission electron microscopy and energy dispersive X-ray spectroscopy. 5-nm intermediate layers, which are likely to be due to the surface activation process, are observed.

In diamond/silicon heterointerfaces fabricated by surface activated bonding at room temperature, an amorphous layer with carbon and silicon is formed in the bonding process, via atomic intermixing across the interfaces. The layer is crystallized by 1000°C annealing, forming a SiC compound.

A polycrystalline diamond substrate treated with a mixture of NH 3 and H 2 O 2 was directly bonded with a plasma-activated Si wafer. They formed atomic bonds by annealing at 250 °C after contacting surfaces in atmospheric air. The bonding method would contribute to the future large-scale integration of diamond heat spreaders with electronics.

SiC and Ga 2 O 3 surfaces were directly bonded by hydrophilic bonding with an ~0.7-nm-thick intermediate layer. The SiC surface was - OH-terminated with hydrofluoric acid, instead of conventional oxidizing treatment, to minimize the formation of the intermediate layer. This would contribute to efficient heat disspation across bonding interface.

This research aims to study the aging behavior of mineral oil, Gas-to-Liquid, and natural ester oil on oil paper insulation. Experiments were carried out on oil insulation, which contained paper insulation, namely kraft paper (TUK), kraft paper (KP), pressboard (PB). Then the oil-paper insulation was placed in a sealed glass bottle & accelerated thermal aging for 1344 hours at a temperature of 150 °C. Observation of oil behavior was carried out at 336 hours intervals during aging. The aging behavior of the oil was observed by testing the oil moisture content, total acid number, breakdown voltage, color scale, interfacial tension, flash point, and Fourier Transform Infrared (FTIR). It was found that natural ester oil had better electrical performance than mineral oil and GTL. Meanwhile, natural ester oils due to their polar nature have different trends in both moisture and acid content when compared to hydrocarbon-based oils. It can be observed there is a relationship between moisture content, acidity, and breakdown voltage in all oils. The color scale shows changes with aging of the three oils, as well as the interfacial tension. Meanwhile, flash point shows the superiority of natural ester oil and GTL has a greater value than mineral oil. FTIR shows the occurrence of transesterification in natural ester oil in the 1700-1800 cm-1 spectrum where in mineral oil and GTL this is not found.

Silica nanofiller or nanosilica is known to be one of the most widely used fillers in polymer nanocomposite. Nevertheless, agglomeration of nanosilica within polymer matrix has been discovered to be a limitation towards enhancing the insulating properties. With this regard, plasma discharge is found to have a great potential in overcoming the agglomeration of nanofiller despite using chemical solvents or coupling agents. The effectiveness of plasma treatment in functionalizing the nanofiller is influenced by few factors, including treatment duration. However, the optimum treatment duration is still yet to be explored to determine its effect on the morphology characteristic of nanofiller. Therefore, this study investigates the effect of plasma treatment duration on nanosilica by varying the treatment times to 1, 3, and 5 minutes. The glow mechanism of plasma discharge is produced by exhilarating the plasma reactor with 0.5 kV and 20 kHz of source parameters. The characteristics of plasma discharge are analyzed according to the discharge current and the properties of the Q-V Lissajous figure. In comparison, the morphology of nanosilica is characterized by using a Perkin Elmer FTIR spectrometer. The result showed that the plasma treatment duration is proportional to the intensity of the hydroxyl group functionalized on the nanosilica morphology with the highest intensity at 5 minutes of treatment time.

Mineral oil has long been used as an insulating liquid in transformers. Natural ester-based oil is an alternative due to its non-toxic and biodegradable characteristics. Then this study compared the rate of degradation of accelerated thermal aging paper impregnated in natural ester oil (NE) with mineral oil (MO) and Gas-to-Liquid (GTL). Sealed glass bottles containing thermally upgraded kraft paper (TUK), kraft paper (KP), pressboard (PB), and oil in an atmospheric environment were aged in an oven at 150 °C within 1344 hours. Observations were made at intervals of 336 hours during the aging. The rate of degradation of the paper was observed through the Degree of Polymerization (DP) test of kraft paper, while the chemical structure of the paper was observed through the Fourier Transform Infrared (FTIR) test of the paper. In addition, acid and moisture tests were also carried out to observe the oil-paper interaction during aging. The depolymerization rate of paper in natural ester oil is smaller compared to other oils. This indicates that NE has better thermal stability and can extend life of the transformer paper. The paper aging rate in MO is similar to GTL Oil because they both are hydrocarbons-based.

Gallium nitride (GaN) substrate was directly bonded with silicon substrate using a sequential wet treatment consisting of H 2 SO 4 /H 2 O 2 and NH 3 /H 2 O 2 mixtures under atmospheric conditions. The bonding strength of the bonded substrates annealed at 300 °C reached up to 6.98 MPa. This study contributes to the development for GaN-based integrated devices.

We successfully fabricate a Ga 2 O 3 /3C-SiC direct bonding by the surface-activated bonding (SAB) of 3C-SiC epitaxial layer grown on Si substrate to Ga 2 O 3 substrate. The structure of bonding interface will be investigated by transmission electron microscope (TEM).

Au/Ta/Ti metal multilayer was developed for the improved vacuum packaging process. Wafer-level packaging after degas at 200 °C and absorbing gas molecules at 300 °C were successfully demonstrated using this multilayer. The activation temperature for gas gettering was lower than that of previous studies using the Au/Pt/Ti layer.

We simulated the growth of SiGe alloys by using reactive force-field (ReaxFF) molecular dynamics simulations in binary systems of SiH x and GeH x and identify the effect of gaseous species on the compositions and crystallinity in alloys. The compositions in alloys could be estimated if compositions of gaseous species can be identified because of the observation of the linear increase in Ge content in alloys. Supplying GeH 2 decreased the crystallinity compared to GeH 3 . The mechanism is described by the mobility and reactivity of the gaseous species and surface structures. These results suggest that the mobility and reactivity of both surface and gaseous species are essential in identifying the effect of gaseous species on composition and crystallinity.

An energy efficient dual-WO 3 electrode was fabricated for electrochromic window application. A vapor-coated WO 3 was prepared using the sputtering deposition method, and a wet-coated WO 3 film was prepared with the wet chemical reaction process. The WO 3 was amorphous crystalline. The intercalated charge of the electrode with a dual-WO 3 layer was 0.0265 C/cm2. High contrast ratio of 55.8% and fast responses of 6 s for charge intercalation and 1.8 s for deintercalation were achieved.

Amorphous carbon films prepared by Chemical Vapor Deposition Method are widely used in oil industry as a protective layer of optical fibers in harsh environments. Clearly, the structural behavior of carbon coating surfaces is straightforward linked to synthesis conditions such as temperature, reactor geometry, precursor gas, fiber drawing speed. In this paper, we report on the effect of precursor gas on the structure and chemical properties of prepared carbon films. This is evidenced through the observed a temperature-dependent hysteresis of dc conductivity that magnitude is about a few percent of the initial resistance of carbon coating. Appearance of hysteresis loop can be explained possible interaction of carbon film with molecules from surrounding media that was revelated by Raman spectroscopy. In order to characterize of the intrinsic heterogeneity of carbon coating prepared by different precursor gases a new spectroscopic parameter was introduced.

Platinum diselenide (PtSe2) as a part of 2D noble transition metal dichalcogenides (nTMDCs) offer diverse optoelectronic properties which can be effectively controlled as number of layers and engineered for novel applications. In this context, our study is focused on structural and compositional characteristics of large area synthesized PtSe2 ultrathin films. In addition, optical properties analysis as a way to track the quality of PtSe2 at different synthesized stages using thermal assisted conversion (TAC) of chemical vapor deposition (CVD) was performed.

The present work aims to study the possibility of activated carbon producing from lignocellulosic biomass - oak sawdust, waste from the furniture industry. The purpose of this work is to characterize the generated cheap and available adsorbents and to consider the possibility of their further application. The precursor and the obtained activated carbon samples were analyzed by several instrumental methods such as Fourier-transform infrared spectroscopy (FTIR) for determination of surface functional groups, Transmission electron microscopy (TEM) for determination of surface morphology, Brunauer-Emmett-Teller (BET) Method for surface area analysis. It was found that the lowest impregnation ratio with the acid favors the development of micro and meso porosity and leads to good texture parameters and high surface area.

We studied a tris(keto-hydrozone) discotic liquid crystal (DLC) and its nanocomposite with single-walled carbon nanotubes (SWCNTs, mean diameter 1.5 nm) at concentration 1 wt.%. The undoped DLC and the DLC nanocomposite were characterized with differential scanning calorimetry (DSC) and UV-Vis absorption spectroscopy, and their properties were compared. Both DLC materials have the characteristics of stable structures and retain their glassy state at room temperature. This is of practical significance for their applications in organic electronics and optoelectronics.

The modes of synthesis of TiO2 films with semiconducting properties by the method of electrochemical oxidation of Ti are proposed for use as an electronic transport layer of perovskite solar cells. To anodize the titanium film, the electrolyte based on a mixture of a 2 % aqueous solution of oxalic acid and a 1 % aqueous solution of sulfamic acids was used. The results obtained showed that Al and Ni have injection contacts to the anodic TiO2 films. Nanoscale titanium oxide films have low resistivity and rectilinear and symmetric I - V characteristic branches. Annealing of titanium oxide films leads to a significant decrease in the resistivity.