Computer Simulation for the Evaluation of the IBM-SNA Congestion Management Method on GULFNET

The work presented in this article aims at using an available computer simulation package for the evaluation of the operation of the IBM-SNA-VRPC congestion management method on the present state of GULFNET, and a future design of the network that includes more nodes and provides higher reliability.     

ZnO thin film nanostructures for hydrogen gas sensing applications

A ZnO thin film-based gas sensor was fabricated using a SiO₂/Si substrate with a platinum comb-like integrated electrode and heating element. The structural characteristics, morphology, and surface roughness of the as-grown ZnO nanostructure were investigated. The film revealed the presence of a c-axis oriented (002) phase with a grain size of 20.8 nm. The sensor response was tested for hydrogen concentrations of 50, 70, 100, 200, 400, and 500 ppm at the optimum operating temperature of 350 °C. The sensitivities towards 50 and 200 ppm of hydrogen gas at 350 °C were approximately 78% and 98%, respectively. A linear response was observed for hydrogen concentrations within the range of 50 ppm–200 ppm. These results demonstrated the potential application of the ZnO nanostructure for the fabrication of cost-effective and high-performance gas sensors.     

Synthesis of energy-induced waste minimization networks (EIWAMINs) for simultaneous waste reduction and heat integration

 This article introduces a process synthesis methodology for identifying cost-effective Energy-Induced Waste Minimization Networks (EIWAMINs). The synthesis methodology is targeted toward retrofit designs for an existing plant or site where environmental emissions (aqueous or gaseous) must be reduced. This approach uses heat-induced separation units that separate mass via a phase change (condensers, dryers, crystallizers, evaporators, etc.) and heat exchangers to simultaneously address waste minimization and heat integration within a large plant or site. While heat-induced separators may be employed for optimal waste separation and allocation (via a phase change), heat exchange equipment (e.g. heaters, coolers, chillers, etc.) may be employed to improve the thermodynamics of existing unit operations. In addition, pressurization/depressurization devices (compressors, turbines, etc.) are also employed to enhance the effectiveness of the heat-induced separators. The problem is tackled via two mathematical formulations which are mixed-integer non-linear programs (MINLPs). The mathematical formulations are combined to identify the most cost-effective design(s) that simultaneously addresses the plant waste minimization and heat integration tasks. Linearization techniques and graphical insights are incorporated to simplify the mathematical formulation of the problem. A case study is provided to highlight the features of this design procedure and its economic merits against several alternative designs. Received: 19 November 1998 / Accepted: 21 January 1999     

Modification of rheological and filtration characteristics of water‐based mud for drilling oil and gas wells using green SiO2 @ZnO@Xanthan nanocomposite

In this study, a green, simple and economical approach was used to synthesise the SiO₂ @ZnO@Xanthan nanocomposite (NC) to modify the rheological and filtration characteristics of the water‐based drilling mud. The green synthesised NCs were identified using scanning electron microscopy, energy dispersive X‐ray spectroscopy, elemental mapping, X‐ray diffraction and UV–Vis analytical techniques. Additionally, the effect of SiO₂ @ZnO@Xanthan NCs on the filtration and rheological properties of mud including apparent viscosity, plastic viscosity, yield point, gel strength, mud cake and fluid loss was investigated. The obtained results confirmed that the synthesised NCs effectively improved the rheological properties of drilling mud, and considerably decreased its fluid loss and filter cake by about 54 and 92.5%, respectively. The results highly recommend the SiO₂ @ZnO@Xanthan NC as an excellent additive to improve the rheological properties, and reduce the fluid loss and the filter cake of the drilling mud.Inspec keywords: X‐ray diffraction, scanning electron microscopy, nanofabrication, additives, nanocomposites, X‐ray chemical analysis, drilling (geotechnical), yield point, rheology, filtration, industrial economics, silicon compounds, zinc compounds, ultraviolet spectra, visible spectra, nanofluidics, gelsOther keywords: rheological properties, fluid loss, drilling mud, filtration characteristics, water‐based mud, green approach, economical approach, X‐ray spectroscopy, mud cake, apparent viscosity, oil‐gas wells, nanocomposite synthesis, scanning electron microscopy, energy dispersive X‐ray spectroscopy, elemental mapping, X‐ray diffraction, Uv–Vis spectroscopy, plastic viscosity, yield point, gel strength, additive, SiO₂ , ZnO     

Four wheel steering control by fuzzy approach

This study introduces a fuzzy four-wheel steering control design method for automotive vehicles. After the analysis of some stability aspects of the vehicle lateral motion, including front steering angle variations, the representation of vehicle nonlinear model by Takagi-Sugeno (T-S) fuzzy model is presented. Next, based on the fuzzy model, a fuzzy controller is developed to improve the stability of the vehicle. Sufficient conditions for stability and stabilization of the T-S fuzzy model using fuzzy feedback controllers is given. To demonstrate the effectiveness of the proposed fuzzy controller, simulation results are given showing the performance improvements of the vehicle in terms of the stability and the maneuverability in critical situations.     

Monitoring of a pharmaceutical nanomilling process using grating light reflection spectroscopy

An optical diagnostic method, grating light reflection spectroscopy (GLRS), has been demonstrated for the in situ monitoring of properties of heterogeneous matrices in industrial processes. The technique is based on measurements near the critical points of intensity and phase in waves reflected from a transmission diffraction grating in contact with a diagnostic sample. The features contained in the reflection spectrum near these thresholds allow for the simultaneous determination of the real and imaginary parts of the dielectric function of the sample. Using these data, the milling progress of highly concentrated fluid suspensions is observed as the material is milled from approximately 40 mm to 160 nm in diameter. A theoretical model that closely resembles experimentally determined spectra was constructed and applied in combination with principal components analysis (PCA) to demonstrate that GLRS can be used to closely monitor changes in the mean particle size of the nanomilled drug product.     

Effect of Prandtl number on the entropy profile across shock waves

Summary The effect of the Prandtl number on the variation of entropy across shock waves is calculated, using the Navier-Stokes equations for the gas phase. The resulting system of three ordinary nonlinear differential equations is reduced to a system of two autonomous nonlinear differential equations, which are solved exactly. This solution, is obtained formally by assuming that the Prandtl number is equal to 3/4. A comparison of the behavior of entropy across shock waves for different values of Prandtl number is given.     

Optimizing size and distribution of voids in phenolic resins through the choice of catalyst types

Phenolics are widely used for over a century in different industries due to their chemical resistance and thermomechanical properties. However, the presence of voids in phenolic resins has negative effects on the mechanical properties and a conventional approach is to avoid these by utilizing very long cure cycles. Our alternative approach investigates the tailoring of void size and distribution to achieve a better balance between processing time and mechanical properties. Therefore, we produced phenolic resin with a void-free microstructure by a long cure cycle as a reference. To alter the void size and distributions, we utilized different catalysts and a short cure cycle to obtain phenolic resins and test their flexural properties with respect to the reference. We investigated the fracture surfaces of all materials by SEM, FTIR and compared results to finite element modeling that confirmed the effects of different void size and distributions on the mechanical properties. © 2019 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48249.     

Silver nanoparticle/r-graphene oxide deposited mesoporous-manganese oxide nanocomposite for pollutant removal and supercapacitor applications

Mesoporous manganese oxide was prepared by a non-ionic surfactant route using Triton X-100, followed by Ag nanoparticle (NP) and graphene oxide incorporation by an ultra-sonication-assisted process. Fine Ag NPs were incorporated into the tubular texture of mesoporous manganese oxide. The crystalline phase, particle size, and morphology of the prepared materials were characterized by X-ray diffraction (XRD), Barrett–Joyner–Halenda–Brunauer–Emmett–Teller analysis, scanning electron microscopy–energy dispersive X-ray analysis, and high-resolution transmission electron microscopy (HR-TEM). The XRD results confirmed the formation of the Mn₂O₃ phase for the as-prepared mesoporous manganese oxide and its nanocomposite. Very fine Ag NPs (<5–10 nm) were obtained. The mesoporous MnO₂ and graphene-incorporated Ag NPs/meso-MnO₂ had a tubular structure and “flaky pastry”-type morphology for the synthesized nanocomposites. HR-TEM images further confirmed the beautiful structural formation upon graphene addition and spherical/dot-shaped NP incorporation into the matrix of MnO₂. Improved surface area was obtained for the Ag NPs and graphene-incorporated mesoporous MnO₂ as compared to bulk MnO₂. The Cr(VI) removal analysis was performed using a batch technique, and enhanced removal of Cr(VI) was achieved (>98% removal of Cr(VI) within 1–2 h of reaction time) for Ag NP-incorporated mesoporous MnO₂. Efficient activity was observed because of the fine Ag NPs present in mesoporous manganese oxide, as opposed to the case of graphene oxide-doped meso-MnO₂ and pristine mesoporous meso-MnO₂.