Co0.5TiOPO4: Crystal structure, magnetic and electrochemical properties

The new titanium oxyphosphate Co_0.5TiPO₅ has been prepared by solid state reaction. Its structure has been determined by single crystal X-ray diffraction and was further investigated by FT-IR spectroscopy and magnetic measurements. The compound crystallizes in the monoclinic system, S.G: P2₁/c [a = 7.358(1) Å, b = 7.378(2) Å, c = 7.383(3) Å, β = 119.66(3)°, Z = 4, R₁ = 0.0142, wR₂ = 0.0429]. The structure can be described as a network of very distorted TiO₆ octahedra, in which the Ti⁴⁺ ions are displaced from the centres of the octahedra, and slightly distorted PO₄ tetrahedra. Half of the octahedral cavities are occupied by Co atoms. The other half of octahedral sites is vacant and favourable for the electrochemical insertion of lithium. The insertion of lithium was studied by galvanostatic charging and discharging between different voltage limits.     

Infective endocarditis in adolescents. Analysis of risk factors for hospital mortality

PURPOSE: To study the epidemiological, clinical, therapeutic and evolutive aspects of endocarditis in a group of patients aging 12 to 20 years-old (mean 15.5). METHODS: Thirty-three consecutive patients (14 males, 19 females) admitted with infective endocarditis were retrospectively studied. RESULTS: Infective endocarditis mortality was 42%. Rheumatic heart disease was the predominant underlying condition in 63% of patients. Congenital heart disease (24%) and cardiac prosthesis (12%) were the other affections involved. The majority of patients (78%) were in functional class III and IV, with more deaths than the 22% who were in functional class I and II (p = 0.01). Staphylococcus aureus was the most frequently isolated agent (42% of the positive blood cultures, followed by Staphylococcus viridans, 21%). Multivariate analysis identified total leukocyte count above 10,000/mm3 and functional class, both at admission (p = 0.01 and p = 0.004, respectively), and the occurrence of embolic complications (p = 0.03) as independent predictors of in-hospital mortality. CONCLUSION: Rheumatic heart disease remains, as in adults, the main predisposing factor for infective endocarditis in adolescents, and S. aureus is, like in children, the leading agent. Mortality is high and functional class at hospital admission, embolic complications and leukocytosis are independent predictors of in-hospital mortality.     

Correction to: SPMI: Single Phase Multiple Initiator Protocol for Coverage in Wireless Sensor Networks

One of the complex problems nowadays in communication systems is the lack of frequency spectrum. To solve this problem, cognitive radio is considered the best candidate that can opportunistically exploit the spectrum. The periodogram based spectrum sensing technique can be used to detect the spectrum in cognitive radio. It is a useful technique since does not need to prior information about the primary signal. In this paper, a new periodogram is presented using the Discrete Cosine Transform (DCT). Results are analyzed and compared with the current raw periodogram. It is observed that the DCT periodogram outperforms the raw technique in terms of probabilities of false alarm and detection, variance, and complexity. In addition, the lowest power of DCT coefficients can be removed without compromising the sensing performance. The proposed system shows high probability of detection with low probability of false alarm even in the case of low Signal-to-Noise Ratio (SNR).     

E-banking Overview: Concepts,Challenges and Solutions

Wireless Personal Communications - The expansion of information technology has led to a new form of banking. Traditional banking, based on the physical presence of the customer, is only a part of...     

A sensitivity analysis method aimed at enhancing the metaheuristics for continuous optimization

An efficient covering of the search space is an important issue when dealing with metaheuristics. Sensitivity analysis methods aim at evaluating the influence of each variable of a problem on a model (i.e. objective function) response. Such methods provide knowledge on the function behavior and would be suitable for guiding metaheuristics. To evaluate correctly the dimensions influences, usual sensitivity analysis methods need a lot of evaluations of the objective function or are constrained with an experimental design. In this paper, we propose a new method, with a low computational cost, which can be used into metaheuristics to improve their search process. This method is based on two global sensitivity analysis methods: the linear correlation coefficient technique and Morris’ method. We propose to transform the global study of a non linear model into a local study of quasi-linear sub-parts of the model, in order to evaluate the global influence of each input variable on the model. This sensitivity analysis method will use evaluations of the objective function done by the metaheuristic to compute a weight of each variable. Then, the metaheuristic will generate new solutions choosing dimensions to offset, according to these weights. The tests done on usual benchmark functions of sensitivity analysis and continuous optimization (CEC 2013) reveal two issues. Firstly, our sensitivity analysis method provides good results, it correctly ranks each dimension’s influence. Secondly, integrating a sensitivity analysis method into a metaheuristic (here, Differential Evolution and ABC with modification rate) improves its results.     

Spintronics based random access memory: a review

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High Field Magnetization Investigation and Mean Field Theory in Amorphous Co<Subscript>75</Subscript>Er<Subscript>17</Subscript>B<Subscript>8</Subscript> Ribbons

Amorphous Co₇₅Er₁₇B₈ ribbons were prepared by the melt spinning technique, and their magnetic properties were studied. Mean field theory was used to describe the temperature dependence of magnetization. High-field magnetization studies performed in magnetic fields up to 15 T have revealed a magnetic behavior typical of a non-collinear magnetic structure of Er and Co sublattices. The simulated magnetization curves show the existence of two critical fields at H _cri1 =?9.5 T and H _cri2 =?94.2 T, corresponding to collinear ferrimagnet, and collinear field-forced ferromagnetic behaviors. The high value of H _cri2 highlights the strong antiferromagnetic interaction between Er and Co sublattices. From the non-collinear regime, the inter-subnetwork molecular field coefficients of the ferrimagnetic alloy were accurately evaluated. In addition, it is shown that the region of canted moments can be satisfactorily described by a phase diagram in the H-T plane.     

Nonlinear output feedback control of V2G single‐phase on‐board BEV charger

In this work, we consider the problem of controlling a single‐phase on‐board battery electric vehicle (BEV) charger with vehicle‐to‐grid (V2G) technology. The BEV charger consists of a bidirectional ac‐dc power converter connected to the single‐phase power grid, followed by a bidirectional dc‐dc power converter interfacing an EV battery pack. The main control objectives are fourfold: (i) Unitary Power Factor (UPF) in grid‐side; (ii) tight dc‐bus voltage regulation; (iii) safety battery charge and battery discharge during the grid‐to‐vehicle (G2V) mode and V2G mode, respectively; and (iv) asymptotic stability of the closed loop system. After an accurate system modelling, a nonlinear controller is designed using a backstepping design technique. The point is that the battery inner voltage is not accessible to measurement. Therefore, a nonlinear observer is invoked in order to estimate all non‐measured variables making the solution cheaper and noiseless. It is shown using a formal analysis and numerical simulations, that the proposed output feedback controller (combining a nonlinear controller and a nonlinear observer) meets all control objectives.     

Thermal Effects in Evaporation from Binary Liquid Mixtures

Thermal effects are considered assuming a volatile component evaporates from a binary liquid mixture in a very long tube. The work is an extension of the work of Chebbi and Selim (2006 Chebbi, R., and Selim, M. S. (2006). The Stefan problem of evaporation of a volatile component from a binary liquid mixture, Heat Mass Transfer, 42(3), 238–247.[Crossref], [Web of Science ®] , [Google Scholar]) (isothermal case) to include evaporative cooling. A similarity solution is provided for the gas–liquid interface temperature and the temperature profiles in the liquid and gas phases. The analysis accounts for the motion of the gas–liquid interface and shows evaporative cooling as expected. The magnitude of evaporative cooling is found significant when volatility of the volatile component is sufficiently high. The validity of the approximations used in the solution is addressed.