Effect of propylation on the characteristics of corn starch and variation of properties with different degrees of substitution

Corn starch was modified by propylation with different degree of substitution (DS). DS of four starch modifications were 0.61, 1.56, 2.27, and 2.51. Samples were characterized by FTIR, XRD, TG‐DTA, swelling power, solubility, water binding capacity, and light transmittance. Results of the systematic physico‐chemical characterization of the starch modification in comparison with the native starch have been documented in the article. Results showed that during propylation, the crystalline structure of starch got destroyed and surface of the starch was eroded. Propylated starch (DS 2.51) showed 85% weight loss at temperatures from 300 to 400°C, whereas the native starch underwent similar weight loss (83%) from 250 to 300°C. Swelling power and water binding capacity of native starch (DS 0.0) were 3.09 g/g and 89.8%, respectively. However, in propylated starch at low DS (DS 0.61), swelling power and water binding capacity increased to 10.55 g/g and 136.8% under same conditions. At high DS (DS 2.51), swelling power was similar to native starch at 65°C, whereas solubility and water binding capacity decreased to below that of native starch. Light transmittance of propylated starch with high DS (DS 2.51) increased dramatically compared with native starch. Propylation improved the hydrophobic transformation and thermal stability of starch at high DS. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Optimization of molecular hydrogen production by Rhodobacter sphaeroides O.U.001 in the annular photobioreactor using response surface methodology

Photofermentative H₂ production at higher rate is desired to make H₂ viable as cheap energy carrier. The process is influenced by C/N composition, pH levels, temperature, light intensity etc. In this study, Rhodobacter sphaeroides strain O.U 001 was used in the annular photobioreactor with working volume 1 L, initial pH of 6.7 ± 0.2, inoculum age 36 h, inoculum volume 10% (v/v), 250 rpm stirring and light intensity of 15 ± 1.1 W m⁻². The effect of parameters, i.e. variation in concentration of DL malic acid, L glutamic acid and temperature on the H₂ production was noted using three factor three level full factorial designs. Surface and contour plots of the regression models revealed optimum H₂ production rate of 7.97 mL H₂ L⁻¹ h⁻¹ at 32 °C with 2.012 g L⁻¹ DL malic acid and 0.297 g L⁻¹ L glutamic acid, which showed an excellent correlation (99.36%) with experimental H₂ production rate of 7.92 mL H₂ L⁻¹ h⁻¹.     

Effect of Pretreatment with Ultraviolet Radiation on the Physicomechanical Properties of Photocured Coir (Cocos nucifera) Fiber with 1-Ethyl-2-Pyrrolidone (1-E-2-P) Monomer

Coir fiber (Cocos nucifera) was modified with 1-ethyl-2-pyrrolidone (1-E-2-P) monomer by photocuring. A series of formulations of different concentration of 1-ethyl-2-pyrrolidone (3, 5, 10, 20, 30, and 70%) in methanol was prepared along with 2% photoinitiator (Darocur-1664). Concentration of 1-E-2-P, soaking time, and radiation doses were optimized and found that 5% 1-E-2-P, 7 min soaking time, and 5th pass of UV radiation was the optimized condition that gave the maximum values as polymer loading (PL) (21%) and 71% higher tensile strength over virgin one. The coir fiber was pretreated with ultraviolet (UV) radiation of various intensities for further improvement of mechanical properties. The mechanical properties, such as TS (tensile strength), Eb (elongation at break), and modulus (σ) of the pretreated fiber, were monitored. Fiber treated with 130th pass of radiation showed the higher TS, Eb, and σ. The fiber irradiated at 130th pass of UV radiation gave the maximum values as PL (35%) and 74% and 18% higher tensile strength and elongation at break, respectively. The fiber, both treated and untreated, was subjected to water absorption. The pretreated and cured coir fiber showed the minimum water uptake behavior.     

Scheduling∕Cost Optimization and Neural Dynamics Model for Construction

A general mathematical formulation is presented for the scheduling of construction projects and is applied to the problem of highway construction scheduling. Repetitive and nonrepetitive tasks, work continuity constraints, multiple-crew strategies, and the effects of varying job conditions on the performance of a crew can be modeled. An optimization formulation is presented for the construction project scheduling problem, with the goal of minimizing the direct construction cost. The nonlinear optimization is then solved by the neural dynamics model developed recently by Adeli and Park. For any given construction duration, the model yields the optimum construction schedule for minimum construction cost automatically. By varying the construction duration, one can solve the cost-duration trade-off problem and obtain the global optimum schedule and the corresponding minimum construction cost. The new construction scheduling model provides the capabilities of both the critical path method (CPM) and linear scheduling method (LSM) approaches. In addition, it provides features desirable for repetitive projects, such as highway construction, and allows schedulers greater flexibility. It is particularly suitable for studying the effects of change order on the construction cost. This research provides the mathematical foundation for development of a new generation of more general, flexible, and accurate construction scheduling systems.     

Four‐band electromagnetic energy harvesting with a dual‐layer metamaterial structure

A four‐band metamaterial harvester for harvesting 0.9 GHz, 1.8 GHz, 2.6 GHz, and 5.8 GHz signals is proposed by a dual‐layer structure. 0.9 GHz and 1.8 GHz bands are harvested by the resistors in front layer, whereas harvesting of 2.6 GHz is achieved by the resistors in second layer. All resistors in front and back layer contribute to harvesting at 5.8 GHz. Numerical calculations are verified by two different full‐wave electromagnetic solvers based on finite‐integration and finite‐element techniques. Power dissipation ratios at 0.9 GHz, 1.8 GHz, 2.6 GHz and 5.8 GHz frequencies concentrated at the resistors are found as 82.3%, 82.8%, 74.6%, and 83.6%, respectively, by the finite‐integration‐based solver. Besides, the finite‐element method‐based solver results in harvesting efficiencies of 79.6%, 93.4%, 73.7%, and 93.8%. The efficiency of the harvester is investigated for different oblique incidences. The proposed metamaterial harvester can be a good candidate for multi‐band absorption and harvesting applications.     

Tuning the gas separation performance of fluorinated and sulfonated PEEK membranes by incorporation of zeolite 4A

Mixed matrix membranes (MMMs) containing fluorinated‐sulfonated poly(ether ether ketone) (F‐SPEEK) and zeolite 4A filler, were prepared by solution casting. F‐SPEEK with a fixed degree of sulfonation (40%) was used for membrane synthesis. The SEM pictures showed good interfacial adhesion between filler particles and polymer, which was also confirmed by the increase in glass transition temperature of MMMs with increase in filler particles. Pure and mixed gas permeation experiments were carried out to investigate the potential of this membrane material. The results revealed that addition of zeolite 4A fillers enhanced both permeability and selectivity owing to the intrinsic nature of polymer and modified membrane morphology due to filler. The highest permeability obtained for CO₂ at 30% filler loading was 49.2 Barrer, while highest selectivities obtained for CO₂/CH₄ and CO₂/N₂ were 55 and 58 compared to 47 and 51 for the unfilled polymer, respectively. Intrinsic CO₂ solubility of F‐SPEEK was observed to be decreased from 10.7 to 1.9 (10^?2) cm³ (STP)/cm³ cmHg with the addition of Zeolite 4A. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45952.     

New control allocation algorithms in fixed point framework for overactuated systems with actuator saturation

In this paper, two control allocation algorithms have been proposed for overactuated systems. The algorithms are developed by formulating constrained control allocation problem into an equivalent fixed point framework. The first algorithm follows sequential solving method while the other one involves a zero finding technique by the Newton method. In order to consider limiting constraints, the saturation function has been taken into account that leads to a nonsmooth zero finding problem and the proposed method guarantees superlinear convergence. The second algorithm is easy to implement and faster than the algorithm developed based on the sequential solving technique. To demonstrate the effectiveness of the proposed algorithms, a detail simulation study has been carried out, in which one example considers both the actuator rate and amplitude constraints.