Flexible Methane Production Using a Proportional Integral Controller with Simulation-Based Soft Sensor

Anaerobic digestion plants have the potential to produce biogas on demand to help balance renewable energy production and energy demand by consumers. A proportional integral (PI) controller is constructed and tuned with a novel tuning method to control biogas production in an optimal manner. In this approach, the proportional part of the controller is a function of the feeding rate and system's degree of stability. To estimate the degree of stability, a simulation-based soft sensor is developed. By means of the PI controller, the requirement for gas storage capacity of the digester is reduced by approximately 30 % compared to a constant, continuous feeding regime of the digester.     

A coloured polyester fabric with antimicrobial properties conferred by copper nanoparticles

In this study, we aimed to produce a coloured polyester fabric through the in situ sonosynthesis of copper nanoparticles using copper sulphate, hydrazine, sodium hydroxide and polyvinylpyrrolidone. The treated fabrics were characterised by X‐ray diffraction, field emission scanning electron microscopy, energy‐dispersive X‐ray spectroscopy and elemental mapping. Moreover, mechanical properties, wettability and antibacterial/antifungal activities of the treated fabrics were evaluated. Central composite design based on the response surface methodology was used to study the effect of copper sulphate, hydrazine hydrate and sodium hydroxide on the weight gain and colour of the treated fabrics. In addition to their roles as reducing agents, hydrazine and sodium hydroxide were responsible for the simultaneous aminolysis and hydrolysis of polyester, increasing the adsorption of nanoparticles on the surface. According to the results, the reddish brown samples treated with copper nanoparticles showed excellent antibacterial and antifungal efficiencies, improved tensile strength and decreased wettability.     

Power law model for subjective mental workload and validation through air traffic control human-in-the-loop simulation

Cognition, Technology & Work - We provide evidence for a power law relationship between the subjective one-dimensional Instantaneous Self Assessment workload measure (five-level ISA-WL scale)...     

Wettability and Rheological Behavior of Low Ag Lead-Free SAC/Graphene and Cobalt-Graphene Nanocomposite Solder Paste

Metallurgical and Materials Transactions A - The impacts of dopant nanoparticles, graphene nanosheets (GNSs) and cobalt decorated-graphene nanosheets (CoGNSs), were studied in relation to the...     

A statistical approach to the optimization of cold‐adapted amylase production by Exiguobacterium sp. SH3

Cold‐adapted enzymes produced by psychrotrophic organisms are interesting from both molecular and biotechnological viewpoints. The enzymes show superior catalytic activity than their mesophilic and thermophilic counterparts at room temperature. Therefore, the enzymes seem interesting for applications where high catalytic activity at ambient temperature is required. In this study, the production of cold‐adapted amylase by Exiguobacterium sp. SH3 was optimized and modeled. In the first step, single factor experiments using shake flask cultures were conducted for primary optimization. These experiments resulted in the improvement of amylase production up to 180 U/mL. In the next step, the Plackett–Burman design was used to identify significant factors affecting the amylase production. Starch concentration, tryptone concentration, and temperature were selected as significant factors; while time, shaking, yeast extract, pH, MnCl₂, CaCl₂, MgCl₂, and KH₂PO₄ were not significant in this step. Finally, the response surface methodology based on central composite design (CCD) was used for further optimization and modeling of the significant factors. The optimization efforts resulted in the maximum amylase production of 730 U/mL, which was four times higher than that achieved by the single‐factor optimization experiments.     

Self-assembly electrode based on silver nanoparticle toward electrogenerated chemiluminescence analysis of glucose

Electrogenerated Chemiluminescence (ECL) involves applying a certain electric potential to a chemical reaction, resulting in the oxidation or reduction of the substance which reacts to produce light. We determined the amount of glucose by its reaction to glucose oxidase (GO _X ) on the surface of the proposed modified electrode, which results hydrogen peroxide (H₂O₂) as side product. After that the reactions between luminol and H₂O₂ under oxidizing conditions generate dependent light which can be used to analyze. In the current article at first we proposed a convenient method to obtaining a self-assembly modified electrode. A nano based modified glassy carbon (GC) electrode (Glucose oxidase/Ag nanoparticles/cysteamine (CA)/p-aminobenzene sulfonic acid/GC electrode) was prepared, and the ECL behavior of luminol in the presence of glucose was examined. Compared to the bare GC electrode, the modified electrode incorporating glucose oxidase significantly enhanced the response of the ECL biosensor to glucose due to the enhanced specificity of the modified surface to enzymatic reaction, and the sensitivity of the luminol ECL reaction. Under optimal conditions, the electrode was established to respond linearly to glucose in the concentration range 5.0×10^?7 to 8.0×10^?3 mol/L, and the detection limit was established to be a glucose concentration of 4.0×10^?8 mol/L.     

In situ synthesis of nano size silicon carbide and fabrication of CSiC composites during the siliconization process of mesocarbon microbeads preforms

CSiC composites with carbon-based mesocarbon microbeads (MCMBs) preforms are a new type of high-performance and high-temperature structural materials for aerospace applications. In the present study, MCMB-SiC composites were fabricated by liquid silicon infiltration (LSI). Physical and mechanical properties such as density, porosity and bending strength were measured before and after siliconization. The results show the CSiC composites have excellent bending strength, density and porosity of 210 MPa, 2.41 g/cm³ and 0.62%, respectively. The chemical analysis shows that the composite is composed of 89% SiC, 2% Si and 9% C. The microstructural results also show the existence of two different areas of SiC, one zone of coarse micron size SiC at SiCSi interface and the other zone consists of fine nano-SiC particles at SiCC interfaces. The formation mechanism governing the siliconization of porous MCMB preform was also investigated.     

Understanding how social media imagery empowers caregivers: an analysis of microcephaly in Latin America

Personal and Ubiquitous Computing - This paper reports the results of a 2-year-long imagery analysis about microcephaly in Latin America from the perspective of caregivers. The content analysis...     

Optimization of enzymatic hydrolysis of wool fibers for nanoparticles production using response surface methodology

Optimization of enzymatic hydrolysis of wool fiber was carried out using a Central Composite Design (CCD) in order to produce wool nanoparticles. The effects of three important determinants, i.e. enzyme loading, substrate concentration and hydrolysis time on enzymatic efficiency were investigated. Polynomial regression model was fitted to the experimental data to generate predicted response such as particle size. The results were subjected to analysis of variance (ANOVA) to determine significant parameters used for optimization. Wool nanoparticles was produced under the attained optimal condition (enzyme loading: 3.3%, substrate concentration: 5 g/l and hydrolysis time: 214 h), followed by ultrasonic treatment. SEM micrographs indicated wool fiber degradation in which the outer cuticle layer was removed and the inner cortical cells were isolated. The results of particle size analysis indicated the positive effect of sonication on reducing particles size further. FTIR spectra denoted no evident changes in the composition of the chemical groups in the macromolecular structure of wool fiber. Besides, the enzymatic hydrolysis and ultrasonic treatment led to an increase in crystallinity, solubility in caustic solution and thermal stability of wool nanoparticles, but caused a decrease in moisture regain comparing to the raw wool fiber.     

Fracture Strength and Surface Magnetic Flux Uniformity in an Isotropic Polymer-Bonded Ring-Shaped Nd-Fe-B Magnet

Ring-shaped (RS) polymer-bonded magnets were produced from a mixture of an isotropic nanocrystalline Nd-Fe-B powder with a nominal composition of 59.8 wt.% Fe, 29 wt.% Nd, 5 wt.% Zr, 4.8 wt.% Co and 1.4 wt.% B and a variety of epoxy resins as binders, using a compaction-molding technique. The morphology and average particle size of the powders are determined by an SEM. The magnetic properties of the magnets were measured using a permeameter. Magnetic flux on the surface of the magnets was determined by a Gauss meter. The mechanical properties of the RS specimens were determined using a tensile fracture strength (FS) test. The effects of polymer type and amount, hardener amount, applied pressing pressure and curing temperature and time on FS were investigated. The experimental results showed that at optimal conditions of 8 wt.% solid epoxy, 3.5 wt.% solid hardener, a pressing pressure of 900 MPa and a curing time of 8 h at 170 °C, a maximum tensile strength of?~?36 MPa was achieved. Surface magnetic flux uniformity in optimal mechanical conditions was also found to be optimum at around?±?40 G, which is one of the best flux uniformities in bonded magnets.