Estimation of reactivity ratios of styrene/butyl acrylate copolymer by ordinary and generalized least square methods

A novel generalized least square (GLS) estimator program was employed for determination of styrene (STY)/butyl acrylate (BA) reactivity ratios synthesized by solution copolymerization method. The monomer reactivity ratios as well as the 95 % individual confidence limits were determined by application of conventional linear methods like Finemann–Ross, Ezrielev–Brokhina–Roskin, Joshi–Joshi, Kelen–Tudos, modified Kelen–Tudos, extended Kelen–Tudos and Mao–Huglin. The estimation process was performed by applying techniques based on ordinary least square (OLS) and GLS approaches and the results were compared. The results showed a fairly good agreement between the experimental and calculated copolymer compositions. The model was then successfully validated through handling regression models with error terms that are heteroskedastic or autocorrelation, or both and clearly showed that the model was able to predict the reactivity ratios by accounting response error structure. Based on the copolymer compositions determined by ¹H NMR, the reactivity ratios of STY and BA were found to be 0.886634 and 0.216369, respectively, by Mao–Huglin method through the GLS approach, and this new estimation method shows the best linear estimations for the monomer reactivity ratios. The present paper shows a new estimation integral approach for determining the monomer reactivity ratios by different conventional linear methods at low and high conversions in EViews software and the calculated values are discussed in terms of regression models.     

Peridynamic assessment of mechanical and thermal characteristics of a defected PMMA/HA composite beam

Polymer-based composites are designed to improve mechanical and thermal characteristics. This study utilized a peridynamic methodology to simulate polymethyl methacrylate/hydroxyapatite composite beams. The simulation involved the crack growth within the computational domain, and an analysis was conducted to evaluate the mechanical and thermal properties of the defected system. The outcomes derived from the peridynamic analysis revealed that an augmentation in the hydroxyapatite ratio within the samples resulted in a decrease in their mechanical and thermal efficiencies. To elucidate further, at an impact velocity of 2 mm/s, the flexural modulus increased to 3.69 GPa, the flexural strength decreased to 132.34 MPa, and the thermal conductivity converged to 0.148 W/m·K, when the hydroxyapatite ratio was at 15%. In the course of the conducted investigations, it became evident that the impact velocity significantly influences the evolutionary behavior of particles within the samples. In particular, with an increase in the impact velocity up to 5 mm/s, the thermal conductivity decreased to 0.139 W/m·K. The results of this study indicate that by modifying the hydroxyapatite ratio and impact velocity, it is possible to control the mechanical and thermal properties of the polymethyl methacrylate/hydroxyapatite composite beams. This optimization allows for their suitability in various engineering applications.     

Field Enhancement in Metamaterial Split Ring Resonator Aperture Nano-Antenna with Spherical Nano-Particle Arrangement

Silicon - In this paper, we present a split ring resonator (SRR) for a nano-aperture antenna for biomedical and spectroscopy applications. We have shown that while the graphene coat layer is...     

Design and analysis of a high quality factor multipath spiral inductor

Microsystem Technologies - Recently high quality factor and small-occupying-area inductors are prerequisite for wireless communication products such as mobile phones and wireless network, low cost...     

Preparation,characterization, and polymerization of chromium complexes‐grafted Al/SBA‐15 and Ti/SBA‐15 nanosupports

Ethylene polymerization catalysts have been prepared by grafting chromium (III) nitrate onto Al/SBA‐15 and Ti/SBA‐15 mesoporous materials. A combination of XRD, nitrogen adsorption, TEM, and inductively coupled plasma‐atomic emission spectroscopy (ICP‐AES), were used to characterize the catalysts. Polymerization activity of Cr/SBA‐15 catalyst is significantly improved by Al or Ti insertion to the supports. Particularly, the chromium catalyst prepared with Ti/SBA‐15 support is more active than Al/SBA‐15 catalyst. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Fabrication of bulk AlN-TiN nanocomposite by reactive ball milling and underwater shock consolidation technique

Reactive milling of aluminum nitride and titanium powders corresponding to the stoichiometric reaction Ti + AlN resulted in the formation of the ceramic matrix composite AlN-TiN. Prolongation of the milling process led to a microstructure with nanosize range of crystallites of both AlN and TiN, evidenced through XRD measurements, SEM and TEM observation. Further, underwater shock compaction with a pressure level of about 10 GPa was applied to the nanocomposite powders to obtain bulk nanostructured sample. The effect of this shock compaction on the prolonged milled powder resulted in a 22% reduction in crystallite size. The average microhardness of the consolidated nanocomposite was 656 HV and 840 HV for 40 h and 100 h MA samples, respectively, with densities 98% of theoretical values in both cases as well as no change in chemical composition.     

Effect of pseudopotential choice on the calculated electron and phonon band structures of palladium hydride and its vacancy defect phases

Density functional theory is increasingly used to predict and understand the properties of hydrogen storage materials. Many such calculations have been performed for various real and hypothetical palladium hydrides, yet despite excellent agreement on electron band structures, significant disparities persist in relation to phonon band structures and critical matters such as dynamic stability of alternative structures. Some disparities may arise because of differing computation approaches between researchers. Therefore in this work a systematic approach was followed to compare calculated electron and phonon band structures for four palladium hydrides: PdH and Pd₃VacH₄ (the superabundant vacancy phase) assuming that octahedral (oct) or tetrahedral (tet) lattice interstices are occupied by H, with six commonly used calculation schemes based on the local density approximation and the generalised gradient approximation, within the harmonic approximation. Of the twenty-four combinations tested, seven are new to the literature. Excellent agreement was found between the calculation schemes for the electron band structures of all four crystal structures. The position regarding phonons is much less satisfactory, however, and highlights the sensitivity of phonon properties to the calculated lattice constants. None of the calculation schemes could reproduce the measured phonon energy gap of PdH(oct) and it is necessary to include anharmonicity of the H potential to obtain realistic results. The calculated lattice constants of PdH(tet) were larger than any observed in experiments, although the structure is dynamically stable. All six calculation schemes predicted dynamic instability for Pd₃VacH₄(oct), although the calculated lattice constant agreed with the estimated zero-temperature experimental value. This structure requires new calculations accounting for anharmonicity. The calculated lattice constant for Pd₃VacH₄(tet) was larger than any experimental value, so this alternative, while dynamically stable, is certainly not observed.     

Development of an analytical model for generation expansion planning as a tool to provide guidelines for preventing instability in the long‐term electricity market

This paper considers the problem of deciding multiperiod investments for generation expansion planning (GEP) in restructured power systems. This problem has presented a challenge for both market managers and suppliers regarding the stability in the electricity market and minimum income for suppliers over the planning period. In this paper, an analytical model for studying the GEP problem from the viewpoint of a central management entity is presented. The aim of this method is to establish a dynamic balance between energy supply and demand by adjustment of GEP over the horizon of planning so that not only the expected profit is provided for all new generating plants but the long‐term stability in the electricity market is also improved. This analytical model can be utilized by regulatory bodies to obtain some guidelines and thereby to set their policies for improving GEP and preventing instability in the long‐term electricity market. To do so, in this study, the uncertainties of demand and supply have been modeled through two stochastic processes. Furthermore, the market price dynamics and their mutual effects on the GEP's results have been considered. Finally, this nonlinear dynamic optimization problem is solved using a modified genetic algorithm (GA). The efficiency and ability of the proposed method are examined on a test power system. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Fabrication,Application and Mathematical Modeling of a new Diamine/Trimesoyl Chloride Reverse Osmosis Composite Membrane for Copper Sulfate Desalination from Wastewaters

Excessive amounts of copper ions in the water sources can be harmful to mammals and especially humans. In this study, a new RO composite membrane is fabricated via the interfacial polymerization (IP) reaction of trimesoyl chloride (TMC), piperazine (PZ) and 3,5-diaminobenzoicacid (DABA). The IP reaction was conducted on a polysulfone (PS) layer which acts as a mounting layer for the separation TMC-DABA-PZ layer. The IP reaction time, TMC concentration and transmembrane pressure were the selected study variables. For IP reaction times around 10 s the rejection and flux were equal to 79% and 21.3 L.m^?2.h^?1, respectively, while increasing the IP reaction time to 40 s elevates the rejection and flux to 92% and 27.7 L.m^?2.h^?1, respectively. TMC concentrations around 0.05% w/w demonstrated rejection and flux equal to 88% and 14.3 L.m^?2.h^?1, respectively, while its elevation to 0.2% w/w, increased the rejection and flux to 90% and 17.5 L.m^?2.h^?1, respectively. As with the transmembrane pressure, the optimum pressure was 20 bars, in which the rejection and flux were 95% and 24.07 L.m^?2.h^?1, respectively. Membrane morphology tests are also supporting evidence for these results. The mathematical modeling has also shown that the relation between the concentration, rejection and flux parameters match the resultant data from the conducted experiments. Since both the rejection and the flux of the fabricated membranes have shown great results, such membranes can be used for wastewater treatment at industrial scales.