Space-Filling Designs for Robustness Experiments

To identify the robust settings of the control factors, it is very important to understand how they interact with the noise factors. In this article, we propose space-filling designs for computer experiments that are more capable of accurately estimating the control-by-noise interactions. Moreover, the existing space-filling designs focus on uniformly distributing the points in the design space, which are not suitable for noise factors because they usually follow nonuniform distributions such as normal distribution. This would suggest placing more points in the regions with high probability mass. However, noise factors also tend to have a smooth relationship with the response and therefore, placing more points toward the tails of the distribution is also useful for accurately estimating the relationship. These two opposing effects make the experimental design methodology a challenging problem. We propose optimal and computationally efficient solutions to this problem and demonstrate their advantages using simulated examples and a real industry example involving a manufacturing packing line. Supplementary materials for the article are available online.     

A computational framework for automating generation of sizing function in assembly meshing via disconnected skeletons

This paper proposes a framework for generating mesh sizing functions for assembly models. Size control is crucial in obtaining a high-quality mesh with a reduced number of elements. The reduction in the number of elements will decrease computation time and memory use during mesh generation and analysis. The framework consists of a background octree lattice for storing the sizing function, a set of source entities for providing sizing information based on geometric information, and an interpolation module for calculating the sizing on the background octree lattice using the source entities. Source entities are generated by performing a detailed systematic study to identify all the geometric factors of an assembly. Disconnected skeletons are extracted and used as tools to measure 3D proximity and 2D proximity, which are two of the geometric factors. The framework facilitates the generation of a variety of meshes with a low computational cost, to meet industry needs. The framework has been tested on many industrial parts, and sizing control on a few typical assemblies has been presented to demonstrate the effectiveness of the proposed framework.     

Electricity Generation and Wastewater Treatment of Oil Refinery in Microbial Fuel Cells Using Pseudomonas putida

Microbial fuel cells (MFCs) represent a novel platform for treating wastewater and at the same time generating electricity. Using Pseudomonas putida (BCRC 1059), a wild-type bacterium, we demonstrated that the refinery wastewater could be treated and also generate electric current in an air-cathode chamber over four-batch cycles for 63 cumulative days. Our study indicated that the oil refinery wastewater containing 2213 mg/L (ppm) chemical oxygen demand (COD) could be used as a substrate for electricity generation in the reactor of the MFC. A maximum voltage of 355 mV was obtained with the highest power density of 0.005 mW/cm² in the third cycle with a maximum current density of 0.015 mA/cm² in regard to the external resistor of 1000 Ω. A maximum coulombic efficiency of 6 × 10⁻²% was obtained in the fourth cycle. The removal efficiency of the COD reached 30% as a function of time. Electron transfer mechanism was studied using cyclic voltammetry, which indicated the presence of a soluble electron shuttle in the reactor. Our study demonstrated that oil refinery wastewater could be used as a substrate for electricity generation.     

A Proteomic Analysis of Human Follicular Fluid: Comparison between Younger and Older Women with Normal FSH Levels

The follicular fluid (FF) is produced during folliculogenesis and contains a variety of proteins that play important roles in follicle development and oocyte maturation. Age-related infertility is usually considered as a problem that can be solved by assisted reproduction technology. Therefore, the identification of novel biomarkers that are linked to reproductive aging is the subject of this study. FF was obtained from healthy younger (20–32 years old) and older (38–42 years old) women undergoing intracytoplasmic sperm injection (ICSI) due to male factor infertility. The FF was analyzed by two-dimensional gel electrophoresis (2-DE). The power of two-dimensional gel electrophoresis and the identification of proteins were exploited using matrix-assisted laser desorption-ionization time-of-flight/time-of-flight (MALDI-TOF-TOF) mass spectrometry. Twenty three protein spots showed reproducible and significant changes in the aged compared to the young group. Of these, 19 protein spots could be identified using MALDI-TOF-TOF-MS. As a result of MASCOT search, five unique downregulated proteins were identified in the older group. These were identified as serotransferrin, hemopexin precursor, complement C3, C4 and kininogen. A number of protein markers were found that may help develop diagnostic methods of infertility.     

Mode shapes and frequencies of radially symmetric vibrations of annular sandwich plates of variable thickness

An analysis and numerical results of radially symmetric vibrations of annular sandwich plates with core of linearly varying thickness are presented. The face sheets are treated as membranes of constant thickness, and the core is assumed to be solid as well as moderately thick. Due to linear thickness variation in the core, the face sheets take the shape of a truncated conical shell and because of this the face sheets membrane forces contribute to the bending and transverse shear of the core of the sandwich plate. Keeping this in view, the equations of motion for such a plate are developed by Hamilton’s energy principle. The frequency equations for three different combinations of boundary conditions, namely clamped at the inner edge and clamped or simply supported or free at the outer edge, are obtained by employing the differential quadrature method. The lowest three roots of these frequency equations have been reported as the frequencies for the first three modes of vibration. The effect of various plate parameters such as taper parameter, thickness of the core at the center, face thickness, and radii ratio on the natural frequencies has been analyzed. Three-dimensional mode shapes for a specified plate for all the three boundary conditions are illustrated. A comparison of results is presented.     

New functional copolymers of <Emphasis Type="Italic">N</Emphasis>-acryloyl-<Emphasis Type="Italic">N</Emphasis>′-methyl piperazine and 2-hydroxyethyl methacrylate: synthesis,determination of reactivity ratios and swelling characteristics of gels

Copolymers of N-acryloyl-N′-methylpiperazine (AcrNMP) and 2-hydroxyethyl methacrylate (HEMA) were synthesized by free radical solution polymerization in dioxane at 70 ± 1 °C, using 2,2′-azobisisobutyronitrile (AIBN) as initiator. The copolymer compositions were analyzed by the methods of FTIR spectroscopy and elemental analysis. Both the method of analysis yielded results that agreed reasonably well. The monomer reactivity ratios of the copolymerization were determined by the linearization methods of Finemann–Ross (FR) and Kelen–Tüdös (KT). The reactivity parameter results derived using FTIR analysis showed that the copolymerization yielded mainly alternating structure with reactivity ratios, r ₁(AcrNMP) = 0.263 ± 0.011 and r ₂(HEMA) = 0.615 ± 0.097 by F–R method and r ₁ = 0.227 ± 0.074 and r ₂ = 0.53 ± 0.15 by KT method. Microstructure data calculated by the method of Igarashi also supports the alternating structure (tendency) of the copolymer. Crosslinked polymer gels of this system exhibited remarkably high swelling of more than 500% in water at ambient temperature.     

Integrated planning in supply chains with buy-side and sell-side marketplaces

In this paper we develop a quadratic programming model for partner selection and planning in integrated supply chain networks embedded with both sell-side and buy-side electronic marketplaces. Such a scenario arises in several practical applications. In particular, we consider a contract manufacturer who procures components from suppliers through a component marketplace and sells its manufactured sub-assemblies to original equipment manufacturers (OEMs), through a sub-assembly marketplace. In these web-enabled supply chains, embedded with upstream and downstream electronic marketplaces, we need methods for online supply-chain partner selection based on pricing and delivery schedules. In this paper, we develop and present such a model that selects partners, synchronizes supply chain activities and optimizes the profit through optimal revenue pricing and cost minimization.     

Synthesis of silica aerogel thin sheets and evaluation of its thermal,electrical, and mechanical properties

Silica aerogels are excellent thermal and acoustic insulators because of interconnected open nanopores with more than 90% porosity and higher surface area. Silica aerogel is derived by sol-gel process and dried under super-critical, sub-critical or ambient pressure conditions. Thin silica aerogel sheets could be effective thermal insulators but high fragility hinders the wider applications. We have successfully developed a synthesis method for thin, flexible, and non-fragile aerogel sheets with excellent hydrophobicity, lower thermal conductivity, and non-combustible properties via ambient drying method. The silica aerogel sheets prepared compose of silica aerogel powder, fiber glass chopped strands, and solvent-based binder. Aerogel thin insulation sheets of thickness 164 μm were prepared by pressing through rollers using aerogel paste composed of aerogel powder, fiber glass strands, and binders. The thermal conductivity values obtained were between 0.02~0.63 W/mK at temperature 25~400°C, contact angle θ = 121‘_, weight loss 3.91% when heated up to 800°C in air, dielectric voltage breakdown 3.67 kV, dielectric strength 6.37 kV/mm and tensile strength of 2.65 N/mm². The overall thermal, electrical, and mechanical evaluation of aerogel thin insulation sheet showed they have higher potential to replace existing thick and bulky aerogel composites as thermal and electrical insulators in aviation, automobiles, electronics, and high power batteries.     

Buckling and vibrations of two-directional FGM Mindlin circular plates under hydrostatic peripheral loading

An analysis is presented for the effect of hydrostatic peripheral loading on the free axisymmetric vibrations of functionally graded moderately thick circular plates on the basis of first-order shear deformation theory. The mechanical properties of the plate material are supposed to vary according to a power-law in both the radial and transverse directions. The numerical solution of the governing differential equation derived by using Hamilton's energy principle for such simply supported and clamped boundary conditions has been obtained employing the harmonic differential quadrature method choosing zeros of Chebyshev–Gauss–Lobatto as the grid points. The effect of different parameters has been analyzed on the frequency parameter for the first three modes of vibration. The critical buckling loads for both the plates have been computed by putting the frequencies to zero. Three-dimensional mode shapes for particular plate have been plotted. Obtained results have been compared.     

NapWell: An EOG-based Sleep Assistant Exploring the Effects of Virtual Reality on Sleep Onset

Virtual Reality - We present NapWell, a Sleep Assistant using virtual reality (VR) to decrease sleep onset latency by providing a realistic imagery distraction prior to sleep onset. Our proposed...