Statistical model for a mode-stirred chamber

The probability density functions for one- and three-dimensional fields in a mode-stirred chamber are derived and verified with chi-square goodness-of-fit tests on experimental data. Each of the three components of the field in the chamber is Rayleigh distributed, which is the same as chi distributed with six degrees of freedom. Each component of the power density is then exponentially distributed. Experimental data confirm these distributions, though unexpected high values, or outliers, were consistently found. Maximum-likelihood estimators of the functions' parameters are derived, and their accuracy is determined as a function of the amount of data. These results are applied to estimating chamber Q. The amount of data required for a given accuracy is determined     

On the preservation of fibre direction during axisymmetric hyperelastic mass-growth of a finite fibre-reinforced tube

Several types of tube-like fibre-reinforced tissue, including arteries and veins, different kinds of muscles, biological tubes as well as plants and trees, grow in an axially symmetric manner that preserves their own shape as well as the direction and, hence, the shape of their embedded fibres. This study considers the general, three-dimensional, axisymmetric mass-growth pattern of a finite tube reinforced by a single family of fibres growing with and within the tube, and investigates the influence that the preservation of fibre direction exerts on relevant mathematical modelling, as well on the physical behaviour of the tube. Accordingly, complete sets of necessary conditions that enable such axisymmetric tube patterns to take place are initially developed, not only for fibres preserving a general direction, but also for all six particular cases in which fibres grow normal to either one or two of the cylindrical polar coordinate directions. The implied conditions are of kinematic character but independent of the constitutive behaviour of the growing tube material. Because they hold in addition to and simultaneously with standard kinematic relations and equilibrium equations, they describe growth by an overdetermined system of equations. In cases of hyperelastic mass-growth, the additional information they thus provide enables identification of specific classes of strain energy densities for growth that are admissible and, therefore, suitable for the implied type of axisymmetric tube mass-growth to take place. The presented analysis is applicable to many different particular cases of axisymmetric mass-growth of tube-like tissue, though admissible classes of relevant strain energy densities for growth are identified only for a few example applications. These consider and discuss cases of relevant hyperelastic mass-growth which (i) is of purely dilatational nature, (ii) combines dilatational and torsional deformation, (iii) enables preservation of shape and direction of helically growing fibres, as well as (iv) plane fibres growing on the cross section of an infinitely long fibre-reinforced tube. The analysis can be extended towards mass-growth modelling of tube-like tissue that contains two or more families of fibres. Potential combination of the outlined theoretical process with suitable data obtained from relevant experimental observations could lead to realistic forms of much sought strain energy functions for growth.     

Sequential Multiple LSB methods and real-time data hiding: variations for Visual Cryptography ciphers

In this paper, a general model approach of real-time data hiding and watermarking for image, video and audio communications is proposed. The aim is the development of security robustness variations and data-rate (capacity) extensions of Steganography fast schemes for RT (real time) or NRT (near real time) image, video and audio media communication and data hiding, with no significant distortion of the medium. Additionally, this paper includes the proposal of specific case models such as Steganography of the total of Visual Cryptography schemes of black and white images. Influenced by our survey on Spatial Domain Steganography techniques such as Multiple LSB (Least Significant Bit) algorithm, Matrix Embedding and Parity Coding, a new potential method is introduced called in brief from now on SMLSB (Sequential Multiple LSB) method comparing other respective methods and algorithms researched, SMLSB is a different approach on real-time and non-real-time data hiding, which gives an advantage of robustness, while it provides various modes of the method depending on the requirements. Also the method can be used for the specific occasion of Visual Cryptography Ciphers’ Steganography.     

Innovative optics for concentrating photovoltaic/thermal (CPVT) systems – the case of the PROTEAS Solar Polygeneration System

The aim of this work is to review the current status of photovoltaic (PV) power generation, focusing on concentrating PVs mainly as regards their typology, market and state-of-the-art feature. The incorporation of a heat recovery system can increase the overall efficiency by exploiting the waste heat. The proposed solution is a Solar Polygeneration System (PROTEAS System) for the simultaneous production of electricity, hot water and air-conditioning. The core of the PROTEAS System is the innovative set-up of total internal reflection reflectors made of plastic (primary optical system), with the potential to concentrate solar rays up to 5000 suns, while specially designed total internal reflection homogenisers (secondary optical system) later homogenise the radiation to 1000 suns. The engineering of the system is an ongoing task, while some of the subsystems have been successfully developed.     

Phosphate coating on pyrite to prevent acid mine drainage

Abstract

Acid mine drainage (AMD) is a serious environmental problem that preoccupies the Canadian Mineral Industry. Considerable amounts of money are spent every year in an effort to prevent or reduce the acid mine drainage phenomenon. AMD occurs when sulfide minerals (ex. pyrite) contained in rock are exposed to air and water and subsequently oxidize to produce low pH water. This acid effluent has the potential to mobilize any heavy metals contained in the rock. Coating the sulfide minerals with iron phosphate is a new promising technology to reduce AMD.Pyrite is treated with a solution containing H₂O₂, KH₂PO₄ and sodium acetate (NaAc). H₂O₂ oxidizes a small part of pyrite producing ferric iron (Fe³⁺) anions. These cations subsequently react with the PO₄ ^3? anions to produce FePO₄ that precipitates on the pyrite surface producing a passive coating. This iron phosphate coating can protect the grains of pyrite from oxidation. This paper presents a series of experiments that confirm that iron phosphate coating can considerably reduce AMD.     

Credit card fraud detection using a deep learning multistage model

The Journal of Supercomputing - The banking sector is on the eve of a serious transformation and the thrust behind it is artificial intelligence (AI). Novel AI applications have been already...     

Soil risk assessment of As and Zn contamination in a coal mining region using geostatistics [corrected

The present paper aims to map As and Zn contamination and assess the risk for agricultural soils in a wider disposal site containing wastes derived from coal beneficiation. Geochemical data related to environmental studies show that the waste characteristics favor solubilisation and mobilization of inorganic contaminants and in some cases the generation of acidic leachates. 135 soil samples were collected from a 34 km(2) area and analysed by using geostatistics under the maximum entropy principle in order to produce risk assessment maps and estimate the probability of soil contamination. In addition, the present paper discusses the main issues related to risk assessment in wider mining and waste disposal sites in order to assist decision makers in selecting feasible rehabilitation schemes.     

Toward persistent autonomous intervention in a subsea panel

Intervention autonomous underwater vehicles (I-AUVs) have the potential to open new avenues for the maintenance and monitoring of offshore subsea facilities in a cost-effective way. However, this requires challenging intervention operations to be carried out persistently, thus minimizing human supervision and ensuring a reliable vehicle behaviour under unexpected perturbances and failures. This paper describes a system to perform autonomous intervention—in particular valve-turning—using the concept of persistent autonomy. To achieve this goal, we build a framework that integrates different disciplines, involving mechatronics, localization, control, machine learning and planning techniques, bearing in mind robustness in the implementation of all of them. We present experiments in a water tank, conducted with Girona 500 I-AUV in the context of a multiple intervention mission. Results show how the vehicle sets several valve panel configurations throughout the experiment while handling different errors, either spontaneous or induced. Finally, we report the insights gained from our experience and we discuss the main aspects that must be matured and refined in order to promote the future development of intervention autonomous vehicles that can operate, persistently, in subsea facilities.     

Ontogenetic development of migration: Lagrangian drift trajectories suggest a new paradigm for sea turtles

Long distance migration occurs in a wide variety of taxa including birds, insects, fishes, mammals and reptiles. Here, we provide evidence for a new paradigm for the determinants of migration destination. As adults, sea turtles show fidelity to their natal nesting areas and then at the end of the breeding season may migrate to distant foraging sites. For a major rookery in the Mediterranean, we simulated hatchling drift by releasing 288 000 numerical particles in an area close to the nesting beaches. We show that the pattern of adult dispersion from the breeding area reflects the extent of passive dispersion that would be experienced by hatchlings. Hence, the prevailing oceanography around nesting areas may be crucial to the selection of foraging sites used by adult sea turtles. This environmental forcing may allow the rapid evolution of new migration destinations if ocean currents alter with climate change.     

Performance of growing–fattening lambs fed whole cotton seed

Effects of diets containing increasing levels of whole cotton seed (WCS) on feed intake, liveweight gain, feed conversion, feeding margin and carcass characteristics were studied. Diets contained 0, 5, 10, 15, 20 and 30% WCS and were fed ad libitum to growing lambs for 54 days. All diets were approximately isonitrogenous (163–186 g crude protein kg⁻¹ dry matter) and isocaloric (19–20 MJ gross energy kg⁻¹ of dry matter). During the first 28 days, four groups of 10 Karagouniko male lambs with initial liveweights of approximately 17·6 kg were fed diets containing 0, 5, 10 and 15% WCS and then, for the next 26 days, diets containing 0, 10, 20 and 30% WCS, respectively. Lambs fed the 15–30% WCS diet ingested about 20 mg kg liveweight⁻¹ day⁻¹ of free gossypol. At 54 days and liveweights of approximately 34·7 kg, five lambs from each treatment were slaughtered and carcass data were collected. There were significant differences in feed intake, liveweight gain, cooler shrink, rumen contents, intestinal fat and liver weight among the lambs fed these diets. Cooler shrink and intestinal fat, and perirenal fat and the combined weight of intestinal and perirenal fat, were significantly (P < 0·05) correlated. Pelleting of the WCS diets reduced the concentration of free gossypol in these diets. It was concluded that WCS was satisfactory as a feed ingredient for growing sheep and can be incorporated into ruminant diets as a source of energy and protein. No indication of gossypol toxicity was detected. © 1998 Society of Chemical Industry