A facile route to carbon-coated SnO2 nanoparticles combined with a new binder for enhanced cyclability of Li-ion rechargeable batteries

Carbon-coated SnO₂ nanoparticles were prepared by a novel facile route using commercial SnO₂ nanoparticles treated with concentrated sulfuric acid in the presence of sucrose at room temperature and ambient pressure. The key features of this method are the simple procedure, low energy consumption, and inexpensive and non-toxic source materials. As-prepared core/shell nanoparticles were characterized by X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDX), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). The electrochemical measurements showed that the carbon-coated SnO₂ nanoparticles with 10% carbon and using carboxymethyl cellulose (CMC) as a binder displayed the best electrochemical performance with the highest specific capacity of 502 mAh g⁻¹ after 50 cycles at a current density of 100 mA g⁻¹. In addition, owing to the water solvability of CMC, the usage of CMC as binder makes the whole electrode fabrication process cheaper and more environmental friendly.     

Evaluation of Minimal of Lubricant in End Milling

When considering machinability parameters, the use of coolant is indispensable in metal cutting operations. However, stricter environmental regulations are making the use of an ample amount of conventional coolant impossible because of its negative impact on the environment. Consequently, the use of minimal quantities of lubricant (MQL) can be regarded as an alternative solution in which the functionality of cooling and lubrication can be achieved by a tiny amount of cutting oil. In this study, flood coolant (42 l min _1) was used compared to the MQL amount of 8.5 ml h_1 and the comparative effectiveness was investigated in terms of cutting force, tool wear, surface roughness, and chip shape. Unlike the catastrophic tool failure in flood cooling, the use of MQL resulted in the cutting edge remaining intact, in spite of a higher flank width. The findings of this study show that MQL may be considered to be an economical and environmentally compatible lubrication technique.     

Studies on the effects of some additives on the physicomechanical properties of urea-ammonium sulphate (UAS) pellets

The effects of some additives on the process of pressing mixed fertilizer based on Urea and Ammonium Sulphate (UAS) at a ratio of 4:1 and their impact on the kinetics of solubility were investigated. UAS pellets were produced using a laboratory pressing machine at an optimum pressure. Most of the inorganic salts with hydrated water gave better crushing strength and lower rates of dissolution as compared with UAS pellets without additives. The organic compound tall pech - a by-product of pulp production - acts as a better binding agent for UAS pellets in respect of both strength and solubility. It is assumed that except for hydrated inorganic salts the tall pech possesses the property of being a slow-release binder in the mixed UAS fertilizer.     

Performance of single crystal diamond tools with different rake angles during micro-grooving on electroless nickel plated die materials

In this study, experiments were carried out to establish the effect of tool rake angle on the performance of single crystal diamond tools in micro-grooving of electroless nickel plated molding dies. Diamond tools with rake angles of 0⁰,+5⁰ and ?5⁰ were used in the study, and it was found that the diamond tool with 0⁰ rake angle has superior performance in terms of tool wear, cutting forces, and machined surface roughness. For a cutting distance of up to 11.69 km, the 0⁰ rake tool machined satisfactorily without any sign of tool wear while the tools with +5⁰ and ?5⁰ rake angles suffered from progressive wear with a corresponding increase in cutting forces. However, it was noted that despite the increase in wear on tools with +5⁰ and ?5⁰ rake angles, and cutting forces on the diamond tools with all three different rake angles did not significantly affect the surface roughness. The effects of various cutting parameters such as spindle speed and infeed rate on the cutting forces and surface roughness are also presented in the study. It was observed that cutting forces increase proportionately with spindle speed and infeed rate without any significant variation of surface roughness. Surface quality of up to 3 nm Ra was achieved during micro-grooving of electroless nickel.     

Effect of High-Pressure Coolant on Machining Performance

Machining of hardened steel and other difficult-to-cut materials requires instant heat transfer from the cutting edge of the tool to improve tool life. Supply of high-volume and high-pressure coolant often provides the best answer. This paper deals with an experimental investigation on the effect of high-pressure coolant on workpiece hardness, comparing it with dry cut and conventional coolant. The effectiveness of high-pressure coolant is evaluated in terms of improvement of surface finish, reduction in tool wear and cutting forces, and control of chip shape. It is found that the cutting force is reduced, surface finish improved, and chip width is reduced with the use of high-pressure coolant.     

Bayesian wavelet-based image denoising using the gauss-hermite expansion

The probability density functions (PDFs) of the wavelet coefficients play a key role in many wavelet-based image processing algorithms, such as denoising. The conventional PDFs usually have a limited number of parameters that are calculated from the first few moments only. Consequently, such PDFs cannot be made to fit very well with the empirical PDF of the wavelet coefficients of an image. As a result, the shrinkage function utilizing any of these density functions provides a substandard denoising performance. In order for the probabilistic model of the image wavelet coefficients to be able to incorporate an appropriate number of parameters that are dependent on the higher order moments, a PDF using a series expansion in terms of the Hermite polynomials that are orthogonal with respect to the standard Gaussian weight function, is introduced. A modification in the series function is introduced so that only a finite number of terms can be used to model the image wavelet coefficients, ensuring at the same time the resulting PDF to be non-negative. It is shown that the proposed PDF matches the empirical one better than some of the standard ones, such as the generalized Gaussian or Bessel K-form PDF. A Bayesian image denoising technique is then proposed, wherein the new PDF is exploited to statistically model the subband as well as the local neighboring image wavelet coefficients. Experimental results on several test images demonstrate that the proposed denoising method, both in the subband-adaptive and locally adaptive conditions, provides a performance better than that of most of the methods that use PDFs with limited number of parameters.     

Testing of algorithms for a stand-alone digital relay for powertransformers

A stand-alone digital relay has been designed and implemented. The relay can be modified easily to accommodate the protection of different types of transformers by changing the software only. Presented in this paper are the real-time experimental results of five selected algorithms implemented using this digital relay. These algorithms are: discrete Fourier transform, Walsh function, rectangular transform, finite impulse response and least-square. Based on the experimental results, the discrete Fourier transform (DFT) algorithm is found to be the best algorithm in terms of accuracy and speed for digital implementation of the differential relay for power transformers     

Sub-Carrier and Band Hopped Orthogonal Frequency Division Multiple Access (OFDMA) Systems

This article proposes a novel way of grouping users in an orthogonal frequency division multiplexing (OFDM) communication link based on predefined criteria. The total available spectrum is divided into a number of bands equal to the number of groups. For efficient time-frequency resource allocation, sub-carrier and band hopping are used simultaneously. Under some constraints, sub-carriers can also be assigned to different users based on known channel characteristics using dynamic sub-carrier allocation. Sub-carrier and band hopping are used for mitigating the frequency selectivity of the wireless channel and for minimizing and avoiding interference in the system. The proposed scheme is equally applicable to both downlink and uplink.

Investigating production-induced stress change at fracture tips: Implications for a novel hydraulic fracturing technique

Hydraulic fracturing from vertical wells subject to reverse faulting stress regimes is found to be problematic due to turning and twisting of propagating fractures, and eventually resulting in ineffective treatments to increase production. The primary motivation of this paper is to investigate whether effective hydraulic fracturing can be achieved in these reservoirs in a number of stages with production intervals. The basic mechanism that is envisaged to achieve a long, planar productive fracture in such a manner is the production-induced change of stress state around the current fracture tip to be suitable for further planar propagation of the fracture in the next treatment stage. The time-dependent production-induced stress state can be formulated by coupled fluid flow and deformation principles. This concept has been applied to a model-scale reservoir to produce some insightful results. Based on results from the model study, the paper has demonstrated the wide implications of the concept for successful hydraulic fracturing in the mentioned reservoir conditions, and highlighted further research directions with full-scale reservoirs.     

Multi-prototype classification: improved modelling of thevariability of handwritten data using statistical clustering algorithms

The principal obstacle in successfully recognising handwritten data is the inherent degree of intra-class variability encountered. This calls for subclass modelling of handwritten data based on the statistically significant variations within the main classes. A novel multi-prototyping approach based on statistical clustering techniques is investigated as an appropriate solution to this problem and very encouraging results have been achieved