A basis for the design of a multiattribute heuristic for single resource project scheduling

Two important characteristics of a project network are the network's topology and the amount of resources available. Most published project scheduling procedures take one or both of these two characteristics into account. Project scheduling procedures that are robust over variations of network characteristics are desirable. The degree of robustness is generally gauged by one or more measures of performance.

The objective of this paper is to compare a set of priority rules that are useful for a single resource project scheduling problem. The set of networks suggested by Patterson (1973) is used along with the set of performance measures proposed by Khattab and Choobineh 1991. The result of this comparison allows one to design a multiattribute heuristic for a single resource project scheduling problem.     

Robust estimation approach for blind denoising.

This work develops a new robust statistical framework for blind image denoising. Robust statistics addresses the problem of estimation when the idealized assumptions about a system are occasionally violated. The contaminating noise in an image is considered as a violation of the assumption of spatial coherence of the image intensities and is treated as an outlier random variable. A denoised image is estimated by fitting a spatially coherent stationary image model to the available noisy data using a robust estimator-based regression method within an optimal-size adaptive window. The robust formulation aims at eliminating the noise outliers while preserving the edge structures in the restored image. Several examples demonstrating the effectiveness of this robust denoising technique are reported and a comparison with other standard denoising filters is presented.     

Preparation and characterization of poly(methyl methacrylate)–lead silicate composites

Poly(methyl methacrylate)–lead silicate composites were prepared with different amounts of crystalline or amorphous PbO–SiO₂ binary composition (70 mole % PbO). The polymerization reaction was carried out in aqueous medium and in methanol–water mixture at 40°C using sodium bisulfite as initiator. The presence of lead silicate was found to increase the molecular weight of the poly(methyl methacrylate). The prepared composites were characterized by studying their shielding properties to γ radiation, mechanical hardness, dielectric constant, and thermal stability. It was found that lead silicate increases the absorbing power of the composites to γ radiation. This behavior was found to be dependent on the amount and the type of lead silicate (amorphous or crystalline). Gamma irradiation of the composites was found to cause chemical degradation of the poly(methyl methacrylate) leading to a decrease in mechanical hardness. Molecular weights of the poly(methyl methacrylate) for some of the composites were determined before and after irradiation viscosimetrically. Dielectric constants for some of the composites were determined at two different temperatures. The thermal stability of the composites was studied by means of an automatic thermogravimetric analyzer.     

Radiation Synthesis and Magnetic Property Investigations of the Graft Copolymer Poly(Ethylene-g-Acrylic Acid)/Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> Film

In this work, acrylic acid (AAc) monomer was grafted onto low-density polyethylene (LDPE) films by the direct method to obtain acid (LDPE-grafted poly(acrylic acid) (LDPE-g-PAAc)) graft copolymers. The presence of the grafted PAAc with COOH groups allows coupling with Fe^2+/3+ ions. The stabilization of Fe₃O₄ particles onto the graft copolymers was done by in situ reduction of LDPE-g-PAAc/Fe^2+/3+ with sodium borohydride (NaBH₄) in aqueous solution. The LDPE-g-PAAc graft copolymer and LDPE-g-PAAc/Fe₃O₄ composite films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), and electron spin resonance (ESR). The synthesized composites exhibit excellent magnetic properties. The results indicated that the magnetic oxide (Fe₃O₄) was embedded and homogenously dispersed into the surfaces of the graft copolymer films as indicated by SEM. The FT-IR analysis clearly suggests that an AAc monomer was effectively grafted onto LDPE. The XRD studies elucidate the change in the crystallinity of the graft copolymers.

Open image in new window

Graphical Abstract The procedures for magnetic film manufacture LDPE-g-PAAc/Fe₃O₄ using gamma irradiation technique

     

Erratum to: Color-secure digital image compression

Multimedia Tools and Applications -     

Quality of dried haskap berries (Lonicera caerulea L.) as affected by prior juice extraction,osmotic treatment,and drying conditions

The effect of juice extraction conditions on the quality of haskap berries (Lonicera caerulea L.) dried at different temperatures (60, 100, and 140°C) was investigated. The conventional juice extraction (process A) consisted of a two-press process, where thawed berries were pressed, and osmotic treatment was applied before pressing again. This was compared with a modified extraction (process B), which applied osmotic treatment during fruit thawing and only one press was used for extraction. The quality parameters investigated included moisture content, pressed berry yield, extraction loss, drying yield, total anthocyanin content (TAC), vitamin C content, and the rehydration characteristics of the final dried berries. Pressing the berries to 70% juice yield resulted in a higher pressed berry yield and better physicochemical quality in the pressed product. The yield was 26.39 and 28.92% in the conventional and modified extraction, with moisture contents of 70.32 and 77.75%, respectively. The TACs of pressed berries from extraction processes A and B were 24.62 and 33.03?mg C-3-G g^?1 DW and the vitamin C contents were 14.14 and 36.18?mg/100?g, respectively. Drying at 60°C until 25% moisture content was better than at higher temperatures, resulting in a better quality dried product. It revealed drying yields of 45.32 and 52.75%, TACs of 4.00 and 4.30?mg C-3-G g^?1 DW, vitamin C contents of 2.97 and 4.91?mg /100?g, and rehydration ratios of 2.22 and 2.37 from processes A and B, respectively. Process B with the one-step extraction is recommended for higher pressed berry yield, higher drying yield, and enhanced quality of the pressed and dried products. It is also a more efficient process, in terms of time, cost, and energy.     

Spontaneous ignition behavior of cotton fabric having different amounts of polyester

Measurements were made on a series of cotton/polyester blends having different compositions. The results showed that the time to ignition increased as the polyester contents of the fabric were increased. An explanation of this observation is given. Both the orientation of the fabric and the temperature of the furnace environment affect the time-to-ignition values. The time to ignition was found to be longer for the fabric loaded in horizontal position than that loaded in vertical position. This difference was attributed to the effect of the forced convection induced inside the furnace. © 1996 John Wiley & Sons, Inc.     

Synthesis and characterization of cellulose nanowhisker-reinforced-poly(ε-caprolactone) scaffold for tissue-engineering applications

Poly(ε-caprolactone) (PCL) is a bioresorbable and biocompatible polymer with assorted medical applications. However, remarkable hydrophobicity and nonosteoconductivity have stood as a barrier to limit its applications. The present study aims to modify the bulk characteristics of PCL to develop a polymeric scaffold with adequate structural and mechanical properties to support regenerated tissues. For this purpose, functionalized bacterial cellulose nanowhiskers (BCNW-g-βCD-PCL₂₀₀₀) are synthesized. Reinforcing PCL matrix with 4 wt % of the nanowhiskers resulted in a bionanocomposite with promoted bulk properties. Compared to neat PCL, the obtained bionanocomposite shows improvements of 115 and 51% in tensile strength and Young's modulus, respectively; 20% increase in hydrophilicity; 7% increase in degradation rate; and 6% decrease in crystallinity. Gas foaming/combined particulate leaching technique is used to develop highly porous structures of 86–95% porosity with interconnected macropores of mean pore diameters of 250–420 μm. Porous scaffolds showed compression modulus values of 5.3–9.1 MPa and would have promising applications in regenerative medicine. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48481.     

Predicting axial piston pump performance using neural networks

A neural network model for an axial piston pump (bent-axis design) is derived in this paper. The model uses data obtained from an experimental setup. The purpose of this ongoing study is the reduction of the power loss at high pressures. However, at the beginning, a study is being done to predict the behavior of the current design of the pump. The neural network model has a feedforward architecture and uses the Levenberg–Marquardt optimization technique in the training process. The model was able to predict the behavior of the pump accurately.     

Modification of the optical and structural properties of ZnO nanowires by low-energy Ar+ ion sputtering

The effects of low-energy (≤2 kV) Ar⁺ irradiation on the optical and structural properties of zinc oxide (ZnO) nanowires (NWs) grown by a simple and cost-effective low-temperature technique were investigated. Both photoluminescence spectra from ZnO NW-coated films and cathodoluminescence analysis of individual ZnO NWs demonstrated obvious evidences of ultraviolet/visible luminescent enhancement with respect to irradiation fluence. Annihilation of the thinner ZnO NWs after the ion bombardment was appreciated by means of high-resolution scanning electron microscopy and transmission electron microscopy (TEM), which results in an increasing NW mean diameter for increasing irradiation fluences. Corresponding structural analysis by TEM pointed out not only significant changes in the morphology but also in the microstructure of these NWs, revealing certain radiation-sensitive behavior. The possible mechanisms accounting for the decrease of the deep-level emissions in the NWs with the increasing irradiation fluences are discussed according to their structural modifications.