Scalable platforms using ant colony optimization

Mass customization necessitates increased product variety at the customers’ end but comparatively lesser part variety at the manufacturer’s end. Product platform concepts have been successful to achieve this goal at large. One of the popular methods for product platform formation is to scale one or more design variables called the scaling variables. Effective optimization methods are needed to identify proper values of the scaling variables. This paper presents a graph-based optimization method called the scalable platforms using ant colony optimization (SPACO) method for identifying appropriate values of the scaling variables. In the graph-based representation, each node signifies a sub-range of values for a design variable. This application includes the concept of multiplicity in node selection because there are multiple nodes corresponding to the discretized values of a given design variable. In the SPACO method, the overall decision is a result of the cumulative decisions, made by simple computing agents called the ants, over a number of iterations. The space search technique initially starts as a random search technique over the entire search space and progressively turns into an autocatalytic (positive feedback) probabilistic search technique as the solution matures. We use a family of universal electric motors, widely cited in the literature, to test the effectiveness of the proposed method. Our simulation results, when compared to the results reported in the literature, prove that SPACO method is a viable optimization method for determining the values of design variables for scalable platforms.     

Efficient online cycle detection technique combining with Steensgaard points‐to information

Pointer analysis is a key static analysis during compilation. Several client analyses and transformations rely on precise pointer information to optimize programs. Therefore, it is paramount to improve the efficiency of pointer analysis. A critical piece of an inclusion‐based pointer analysis is online cycle detection. The efficiency of pointer analysis is significantly influenced by the efficacy of detecting cycles. Existing approaches perform poorly when they guess cycle formation in the constraint graph. Thus, the number of false cycle‐detection triggers of the state‐of‐the‐art methods is considerably high (over 99% on Standard Performance Evaluation Corporation (SPEC) benchmarks). In this paper, we propose bootstrapping as a way to improve cycle detection predictability of pointer analysis. The main idea is to run a sequence of increasingly precise analyses to feed into the next more precise analysis to improve the efficiency of the latter analysis. In this process, we develop a new notion of pointer equivalence called constraint equivalence. Using Steensgaard's fast unification algorithm as the bootstrap, we devise a new cycle detection method for Andersen's inclusion‐based analysis. We measure the effectiveness of our approach using a suite of programs including SPEC 2000 benchmarks and two open‐source programs, and find that our method can reduce the number of false cycle detections by almost 22× compared with a state‐of‐the‐art method. This leads to an overall analysis time improvement of 18% on an average. Copyright © 2015 John Wiley & Sons, Ltd.     

Challenges of long-term vascular access in pediatric hemodialysis: Recommendations for practitioners

Kidney transplantation is the preferred treatment of end-stage renal disease in children. However, time to transplant varies, making a well-functioning long-term vascular access essential for performing hemodialysis efficiently and without disruption until a kidney becomes available. However, establishing long-term vascular access in pediatric patients can present distinct challenges due to this population's unique characteristics, such as smaller body size and lower-diameter blood vessels. There are three main pediatric long-term vascular access options, which include central venous catheters (CVC), arteriovenous fistula (AVF), and arteriovenous graft (AVG). CVC are currently the most widely used modality, although various studies and guidelines recommend AVF or AVG as the preferred option. Although AVF should be used whenever possible, it is crucial that clinicians consider factors such as patient size, physical exam findings, comorbidities, predicted duration of treatment to decide on the most optimal long-term vascular access modality. This article reviews the three long-term vascular access methods in children and the benefits and complications of each.     

A lithium poly(pyromellitic acid borate) gel electrolyte membrane for lithium-ion batteries

Lithium poly(pyromellitic acid borate) (PPAB) was synthesized via polymerization of lithium tetramethanolatoborate and silylated pyromellitic acid. The synthesized material was characterized by Fourier transformation infrared spectroscopy, ¹¹B nuclear magnetic resonance, scanning electron microscopy, and thermogravimetric analysis. And electrochemical characterizations were carried out on the blended PPAB/PVDF-HFP membrane. The PPAB-based composite membrane exhibits high lithium ionic conductivity, a broad electrochemical window and a high lithium-ion transference number. The battery cells assembled with the PPAB/PVDF-HFP/EC:PC composite membrane as the electrolyte perform reasonably well not only at elevated temperature but also at room temperature with good cyclability and discharge capacity, making the material suitable for applications in lithium-ion batteries.     

Flexible supercapacitor based on three‐dimensional cellulose/graphite/polyaniline composite

Fast charge‐discharge rate and high areal capacitance, along with high mechanically stability, are the pre‐requisites for flexible supercapacitors to power flexible electronic devices. In this paper, we have used three‐dimensional polyacrylonitrile graphite foam as flexible current collector for electro‐deposition of polyaniline (PANI) nanowires. The graphite foam with PANI was then used to fabricate symmetric supercapacitor. The fabricated supercapacitor in the three‐electrode system shows a high specific capacitance (C_sp) of 357 F.g^?1 and areal capacitance (C_areal) of 7142 mF.cm^?2 in 1 M H₂SO₄ at current density of 80 mA.cm^?2, while using two‐electrode system, it shows C_sp of 256 F.g^?1 and C_areal of 5120 mF.cm^?2 in 1 M H₂SO₄ at current density of 100 mA.cm^?2. The current density of 100 mA.cm^?2 is up to 10 folds higher than reported current densities of many PANI‐based supercapacitors. The high capacitance can be attributed to the spongy network of PANI‐NWs on three‐dimensional graphite surface which provides an easy path for electrolyte ions in active electrode materials. The developed supercapacitor shows specific energy of 64.8 Whkg^?1 and a specific power of 6.1 kWkg^?1 with a marginally decrease of 1.6% in C_sp after 1000^th cycles, along with coulombic efficiency retention of 87% in polyvinyl alcohol/H₂SO₄ gel electrolyte. This flexible supercapacitor exhibits great potential for energy storage application.     

A relative assessment of sub grid scale models for large eddy simulation of co-axial combustor

Large eddy simulation (LES) of a co-axial combustor is reported. Accuracy of LES depends on the ability of the sub-grid scale (SGS) models to predict the turbulent viscosity. The sensitivity of LES results for different SGS models is established for a coaxial annular combustor. The radial, axial and tangential velocity distribution predicted by four sub-grid scale models is compared with the experimental results of Sommerfeld and Qiu. It is observed that the flow physics is captured more accurately by WALE model as compared to other SGS models. The predictions of WALE model are closer to the experimental results for all stations in the flow domain.     

Block Copolymer Nanostructures and Their Applications: A Review

Block copolymer nanostructures are smart, intelligent, and environment sensitive nanostructures designed to respond in a controlled manner to an external stimulus. Block copolymer nanostructures are being extensively utilized in pharmaceutical field, nanotechnology, and inforensics. Upon micellization, the hydrophobic core of block copolymer nanostructures region serves as a reservoir for hydrophobic medication, which can be loaded by chemical, physical, or electrostatic means. DNA combined with synthetic block copolymer nanostructure enhances the chemical and biological behaviors of biomacromolecule and at the same time completely suppress undesirable properties. Novel Nanoelectromechanical Systems/Microelectromechanical Systems (NEMS/MEMS) devices are being realized using block copolymer nanostructures and DNA combined with inorganic material nanoparticles and small organic moieties.     

CFD modeling of solid-liquid fluidized beds of mono and binary particle mixtures

CFD simulation of bed expansion of mono size solid-liquid fluidized beds has been performed in creeping, transition and turbulent flow regimes, where Reynolds number (Re_∞=d_pV_S∞ρ_L/μ_L) has been varied from 0.138 to 1718. It has been observed that the predicted values of bed voidage using the drag law of Joshi [1983. Solid-liquid fluidized beds: some design aspects. Chemical Engineering Research and Design 61, 143-161] and Pandit and Joshi [1998. Pressure drop in packed, expanded and fluidized beds, packed columns and static mixers—a unified approach. Reviews in Chemical Engineering 14, 321-371] (which has been derived from the first principals), exhibited an excellent agreement with the Richardson and Zaki equation. CFD simulations have also been performed for the prediction of segregation and/or intermixing of binary particle systems having the ratio of terminal settling velocity over a range from 3.2 to 1.06. The Reynolds number has also been varied over the range of 0.33 to 2080. It has been observed that the present CFD model explains all the qualitative and quantitative observations reported in the published literature (complete segregation, partial segregation, complete intermixing, etc) and these predictions are in good agreement with the experimental results. The present CFD model also predicts successfully the layer inversion phenomena which occur in the binary particle mixtures of different size as well as density. Further, the critical velocity at which the complete mixing of the two particle species occurs has also been predicted.