Development of a mathematical model for a curved slat venetian blind with thickness

This article is about the development of a mathematical model for a venetian blind. The model is used for determining the performance of the glass window installed with a venetian blind in term of heat transmission. The blind, whose optical properties are considered nonspecular, is modeled as an effective layer. The optical properties of the effective layer are mainly dependent on the slat angle, slat properties and solar profile angle. The effect of slat curvature and the effect of slat thickness are included in the developed model. The shortwave optical properties of the effective layer, transmittance, reflectance and absorptance, are classified as the optical properties for direct radiation and the optical properties for diffuse radiation. The analysis for optical properties due to the interreflection of the direct radiation between the adjacent slat surfaces is done by using radiosity method on a 6 surface closed enclosure. The effect of the slat curvature and thickness causes the shaded area blocked by the blind itself increased in certain cases. The optical properties for diffuse radiation of the effective layer are determined considering the incident diffuse radiation from the sky and from the ground. The optical properties calculated from the developed model are also compared to the results obtained from the three previous models. The validation of the results predicted by the developed mathematical model is performed by comparing the predicted results with the experimental results. The results that used to validate in this study is the ratio of the transmitted radiation through the glass window installed with venetian blind to the incident radiation on the glass window. It is shown from the comparison that the developed mathematical model for the venetian blind included the curvature and thickness effect yields quite accurate predicted results.     

Glass Fiber/Polyphthalamide Composites for 3D-Molded Interconnect Devices Application: Structure and Properties

The research work was to demonstrate the feasibility of a three-dimensional molded interconnect devices concept using the injection-molding technique and to investigate the effects of weld/meld line types on the structure and properties. Two different polymers based on polyphthalamide/glass fiber composites (PA6 T/X and PA10 T/X composites) were produced by injection molding at the different processing conditions. A mold was designed in such a way that a weld and meld line can be produced at different angles by changing an insert inside the mold. The mechanical properties such as stiffness, tensile strength, and flexural strength were determined in tensile and flexural tests, respectively. The adhesive strength and electrical resistance were studied with the pull-off process and four-point measurement, respectively, and are discussed. The dispersion of the glass fiber and types of meld/weld line were inspected using scanning electron microscopy. The results were in-line with the expectation of a reduction in mechanical properties in areas where weld/meld lines occurred. The results of tensile tests clearly showed that the weld and meld lines showed a considerable influence on mechanical properties. It was found that the tensile and flexural strength of polyphthalamide/glass fiber composites with weld line type decreased approximately 58 and 62%, respectively, compared to the composites without the weld line. On the other hand, the effects of injection time and mold temperature on the tensile strength were marginal.     

Inhibition of biofilm formation,adhesion and invasion in Caco-2 cells by foodborne pathogens using phyto-mediated synthesised silver nanoparticles from industrial wastes

Certain foodborne diseases are associated with antibiotic resistance, a significant problem throughout the world. Silver nanoparticles (AgNPs) using industrial waste from Eucalyptus camaldulensis and sericin, a protein derived from Bombyx mori, were synthesised by a one-step approach. Spherical-shaped nanoparticles with the average size of 17.19 nm exhibited strong antioxidant activity. The minimum bactericidal concentrations against foodborne pathogens including Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, Escherichia coli O157:H7, Klebsiella pneumoniae, Salmonella Typhimurium, Shigella sonnei, Vibrio cholerae and Vibrio parahaemolyticus were between 2.96 and 11.83 µg/mL. Killing against L. monocytogenes and E. coli O157:H7 was observed within 4 h. Treatment with AgNPs at 0.25 – 0.5 × MIC significantly reduced biofilm production in all isolates (P < 0.05). AgNPs significantly impeded adhesion to and invasion of human epithelial Caco-2 cells by L. monocytogenes and E. coli O157:H7 (P < 0.05). Biocompatibility assessment of AgNPs with Caco-2 and human red blood cells demonstrated no toxic effects.     

Toward Macroscale,Isotropic Carbons with Graphene‐Sheet‐Like Electrical and Mechanical Properties

Realization of macroscale three‐dimensional isotropic carbons that retain the exceptional electrical and mechanical properties of graphene sheets remains a challenge. Here, a method for fabricating graphene‐derived carbons (GDCs) with isotropic properties approaching those of individual graphene sheets is reported. This synthesis scheme relies on direct cross‐linking of graphene sheets via the functional groups in graphene oxide to maximize electronic transport and mechanical reinforcement between sheets and the partial restacking of the sheets to increase the material density to about 1 g cm^‐3. These GDCs exhibit properties 3–6 orders of magnitude higher than previously reported 3D graphene assemblies.     

Development of a model for calculating the longwave optical properties and surface temperature of a curved venetian blind

This article is about the development of a mathematical model for calculating the longwave optical properties of a curved venetian blind. The calculated optical properties are used to determine the performance of the glass window installed with a venetian blind in terms of thermal comfort. The blind, whose optical properties are considered nonspecular, is modeled as an effective layer. The effect of slat curvature is included in the developed model. A six surface enclosure formed by two consecutive slats is used to analyze for the longwave optical properties of the effective layer. The longwave optical properties, transmittance, reflectance, absorptance and emittance are developed by using the radiosity method. The steady state energy balance method along with the developed longwave optical properties are used to determine the surface temperature of the effective layer. The empirical expression for the total heat flux from the indoor glass window surface with an adjacent venetian blind is adopted in the developed model. The surface temperature of the blind, which is the key parameter for calculating the thermal performance of glass windows with venetian blinds with respect to thermal comfort, is chosen as the parameter used for the model validation. The predicted surface temperature of the venetian blind is compared with the surface temperature of the venetian blind obtained from the measurement. The agreement between the predicted temperature and the measured temperature is good.     

MFOA‐integrated modified inverted F‐based adaptive array Antenna for 2.4 GHz band applications

This research has proposed a modified fruit fly optimization algorithm (MFOA)‐integrated adaptive array antenna (AAA) for the 2.4–2.5 GHz WLAN system. The principal components of the array antenna system encompass four array elements, four band pass filters (BPF), four digital phase shifters, a four‐way power combiner/splitter, a directional coupler, a radio frequency (RF) detector, and a microcontroller unit (MCU). In the realization of the adaptive antenna system, the modified inverted F antenna with a finite ground plane was first innovated and subsequently deployed as the element of the four‐element array antenna. In the study, simulations and experiments were carried out with the four‐element AAAs of two configurations, i.e. the linear and planar array configurations. The simulation and experimental results revealed that the MFOA algorithmic scheme could determine the direction of the maximum arrival signal in an efficient and accurate manner and also was capable of manipulating the radiation pattern in the desired direction. In addition, the MFOA‐integrated four‐element AAA is of compact size (20 mm × 35 mm × 1.8 mm) and operable in the 2.31–2.55 GHz frequency band with omnidirectional radiation pattern and a gain of 1.6 dBi. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2016.