A different method for producing a flexible LiMn2O4/MWCNT composite electrode for lithium ion batteries

A flexible lithium manganese oxide (LiMn₂O₄)/multi-wall carbon nanotube (MWCNT) composite electrode was produced by casting a slurry-containing powdered LiMn₂O₄ on a previously prepared MWCNT paper. The structure of this new LiMn₂O₄/MWCNT composite electrode was characterized using scanning electron microscopy and X-ray diffraction patterns. Furthermore, the surfaces of these electrodes were coated with gold–palladium alloy using an RF magnetron sputtering technique to prevent Mn dissolution. To investigate the electrochemical performance of this flexible LiMn₂O₄/MWCNT composite electrode, a bare-LiMn₂O₄ electrode was prepared. The discharge capacity of the produced LiMn₂O₄/MWCNT nanocomposite electrode was cyclically tested, and the charge transfer resistance of the electrodes was studied using electrochemical impedance spectroscopy. Consequently, the Au–Pd-coated LiMn₂O₄/MWCNT had a 120 mAh g^?1 discharge capacity and 90 % capacity retention after 100 cycles.     

The frictional sliding contact problems of rigid parabolic and cylindrical stamps on graded coatings

Graded materials, also known as functionally graded materials (FGMs), are generally two-phase composites with continuously varying volume fractions. Used as coatings and interfacial zones they can reduce thermally and mechanically induced stresses resulting from material property mismatch, increase the bonding strength and provide protection against adverse environments. In this paper, the contact problems of parabolic and cylindrical stamps on graded coatings are considered. The objective of this study is to obtain a series of analytical benchmark solutions for examining the influence of such factors as material inhomogeneity constants the coefficient of friction and various length parameters on the critical stresses that may have a bearing on the fatigue and fracture of the components with graded coatings.     

Investigation of surface roughness of aluminium solid mould investment castings

Solid investment moulds are used for precious or non-precious metals and alloys castings, the most common application areas are dental prosthesis and jewellery fabrications. Investment casting is known for high dimensional accuracy and smooth surface finish. Casting of ultra-thin sections and small complex parts require vacuum assisted or centrifugal filling. In this study, solid investment casting of aluminium has been tried and surface quality of the castings was investigated. Specially designed steppedwedge surface roughness specimens were produced with A413 aluminium alloy casting into gypsum bonded solid moulds. Casting operations were carried out in two ways; the first only with gravitational force and the second with vacuum assistance. Surface roughness of as cast specimens were measured, effects of section thickness, vacuum assistance and location of the pattern on the wax tree were determined.     

Satellite-based and mesoscale regression modeling of monthly air and soil temperatures over complex terrain in Turkey

Simple regression algorithms were developed to quantify spatio-temporal dynamics of minimum and maximum air temperatures (T_min and T_max, respectively) and soil temperature for a depth of 0-5 cm (T_soil-5cm) across complex terrain in Turkey using Moderate Resolution Imaging Spectroradiometer (MODIS) data at a 500-m resolution. A total of 762 16-day MODIS composites (127 images × 6 bands) between 2000 and 2005 were averaged over a monthly basis to temporally match monthly T_min, T_max, and T_soil-5cm from 83 meteorological stations. A total of 60 (28 temporally averaged plus 32 time series-based) linear regression models of T_min, T_max, and T_soil-5cm were developed using best subsets procedure as a function of a combination of 12 explanatory variables: six MODIS bands of blue, red, near infrared (NIR), middle infrared (MIR), normalized difference vegetation index (NDVI), and enhanced vegetation index (EVI); four geographical variables of latitude, longitude, altitude, and distance to sea (DtS); and two temporal variables of month, and year. The best multiple linear regression models elucidated 65% (RMSE = 5.9 °C), 65% (RMSE = 5.1 °C), and 57% (RMSE = 6.9 °C) of variations in T_min, T_max, and T_soil-5cm, respectively, under a wide range of T_min (−34 to 25 °C), T_max (0.2-47 °C) and T_soil-5cm (−9 to 40 °C) observed at the 83 stations.     

SVD‐aided EKF attitude estimation with UD factorized measurement noise covariance

This paper describes singular value decomposition (SVD) aided extended Kalman filter (EKF) for nanosatellite's attitude estimation. The development of the filter kinematic/dynamic model, the measurement models of the sun sensors, and the magnetometers used to generate vector measurements are presented. Vector measurements are used in SVD for satellite attitude determination purposes. In the proposed method, EKF inputs come from SVD as the linear measurements of attitude angles and their error covariance. In this step, UD factorizes the attitude angles error covariance, forming the measurements in order to obtain the appropriate inputs for the filtering stage. Results are presented and analyzed in addition to discussion of the sub‐step, which is the UD factorization on the measurement covariance. The accuracy of the estimation results of the SVD‐aided EKF with and without UD factorization is compared for estimation performance.     

Real-time multi-camera video analytics system on GPU

In this article, parallel implementation of a real-time intelligent video surveillance system on Graphics Processing Unit (GPU) is described. The system is based on background subtraction and composed of motion detection, camera sabotage detection (moved camera, out-of-focus camera and covered camera detection), abandoned object detection, and object-tracking algorithms. As the algorithms have different characteristics, their GPU implementations have different speed-up rates. Test results show that when all the algorithms run concurrently, parallelization in GPU makes the system up to 21.88 times faster than the central processing unit counterpart, enabling real-time analysis of higher number of cameras.     

Highly transparent, flexible, and thermally stable superhydrophobic ORMOSIL aerogel thin films

We report preparation of highly transparent, flexible, and thermally stable superhydrophobic organically modified silica (ORMOSIL) aerogel thin films from colloidal dispersions at ambient conditions. The prepared dispersions are suitable for large area processing with ease of coating and being directly applicable without requiring any pre- or post-treatment on a variety of surfaces including glass, wood, and plastics. ORMOSIL films exhibit and retain superhydrophobic behavior up to 500 °C and even on bent flexible substrates. The surface of the films can be converted from superhydrophobic (contact angle of 179.9°) to superhydrophilic (contact angle of <5°) by calcination at high temperatures. The wettability of the coatings can be changed by tuning the calcination temperature and duration. The prepared films also exhibit low refractive index and high porosity making them suitable as multifunctional coatings for many application fields including solar cells, flexible electronics, and lab on papers.     

Frictional Hertzian contact between a laterally graded elastic medium and a rigid circular stamp

This study investigates the problem of sliding frictional contact between a laterally graded elastic medium and a rigid circular stamp. Analytical and computational methods are developed to evaluate the contact stresses. In the analytical formulation, spatial variation in the shear modulus of the graded medium is represented by an exponential function, and Poisson’s ratio is taken as a constant. Coulomb’s dry friction law is assumed to hold within the contact area. The two-dimensional plane elasticity problem is formulated utilizing Fourier transforms, and the resulting Cauchy-type singular integral equation of the second type is solved by applying an expansion–collocation technique. The finite element method is used in the computational analysis of the contact problem. In the finite element model, continuous variation of the shear modulus is taken into account by specifying this property at the centroid of each finite element. The finite element-based solution procedure is verified by making comparisons to the results obtained through the analytical method. Numerical results generated for the laterally graded medium with an exponential variation in the shear modulus illustrate the influences of lateral gradation and coefficient of friction upon the contact stress distributions. The capability of the proposed finite element method is further demonstrated by providing numerical results for a laterally graded medium whose shear modulus is represented by a power function.     

New Magnesium Composite with Mg17Al12 Intermetallic Particles

Powder Metallurgy and Metal Ceramics - Although magnesium is one of the materials with the lowest density, its application is limited amongst other commercial materials due to insufficient...     

A Study on Tunable Viscoelastic Properties of Xhantan Gum and Sodium Alginate Hyrogelling System

Theoretical Foundations of Chemical Engineering - In this study, viscoelastic properties of xhantan gum (XG) and sodium alginate (SA) hydrogelling system were investigated at a definite range of...