Effect of Power Amplifier Nonlinearity on the Physical Layer Security of MIMO Systems

Wireless Personal Communications - This paper presents an analytical investigation on the effect of nonlinear high-power amplifiers on the physical layer security of multiple-input-multiple-output...     

A practical approach for modelling and control of biomass pyrolysis pilot plant with heat recovery from combustion of pyrolysis products

A pilot plant of biomass pyrolysis using pyrolysis products as fuel has been tested and shown to improve energy balance of the process and to be environmentally friendly by avoiding rejection of pyrolysis pollutants fumes into the atmosphere. The high number of parameters involved in a pyrolysis process makes it difficult to specify an optimum procedure for charcoal yield and pyrolysis cycle durability. So the knowledge of the essential parameters which govern the kinetics mechanisms of the biomass thermal decomposition and the combustion of pyrolysis gases is very useful to understand the operating cycle of the plant. In the present study a thermochemical model is developed in order to simulate and control the operating cycle of the system. The effect of the inlet molar air flow rate on the temporal evolution of biomass mass loss rate and temperatures in the different active zones of the pilot plant as well as the determination of the critical inlet molar air flow rate for which accidental runaway of combustion reactions occurs are presented. To avoid this accidental phenomenon a Proportional-Integral-Derived (PID) anticipated regulation is used in order to control temperatures evolution in the different zones of the device and avoid the runaway of combustion reactions.     

N-3 Polyunsaturated Fatty Acids Modulate In-Vitro T Cell Function in Type I Diabetic Patients

In this work, we assessed the in-vitro effects of eicosapentaenoic acid (EPA; C20:5n-3) and docosahexaenoic acid (DHA; C22:6n-3) (final concentration, 15 microM) on T cell blastogenesis, interleukin-2 and -4 (IL-2, IL-4) secretion, fatty acid composition and intracellular oxidative status in type I diabetic patients with or without complications. Con A stimulated lymphocyte proliferation, glucose uptake, intracellular reduced glutathione levels and catalase activity were lower in diabetics as compared to controls, regardless to the presence of complications. EPA and DHA diminished T-lymphocyte proliferation and IL-2 production but enhanced IL-4 secretion in both diabetic and control groups. No changes in the levels of reduced glutathione and in the activities of catalase and SOD were observed in control T cells cultured in the presence of EPA and DHA. However, in diabetic patients, addition of n-3 PUFA to culture induced an increase in T cell levels of reduced glutathione and hydroperoxide, and in activities of catalase and SOD. Low levels of arachidonic acid (C20:4n-6) were found in plasma membrane phospholipids of lymphocytes from diabetic patients compared to controls. Incubation of lymphocytes with EPA and DHA was associated with an incorporation of these fatty acids in membrane phospholipids. In conclusion, the beneficial effects of n-3 PUFA on T cell functions in type I diabetes could be attributed to their suppressive action and modulation of cytokine secretion, and to the improvement of intracellular oxidative status.     

ADR-SPLDA: Activity discovery and recognition by combining sequential patterns and latent Dirichlet allocation

This paper presents ADR-SPLDA, an unsupervised model for human activity discovery and recognition in pervasive environments. The activities are encoded in sequences recorded by non-intrusive sensors placed at various locations in the environment. Our model studies the relationship between the activities and the sequential patterns extracted from the sequences. Activity discovery is formulated as an optimization problem in which sequences are modeled as probability distributions over activities, and activities are, in turn, modeled as probability distributions over sequential patterns. The optimization problem is solved by maximization of the likelihood of data. We present experimental results on real datasets gathered in smart homes where people perform various activities of daily living. The results obtained demonstrate the suitability of our model for activity discovery and characterization. Also, we empirically demonstrate the effectiveness of our model for activity recognition by comparing it with two of the widely used models reported in the literature, the Hidden Markov model and the Conditional Random Field model.     

A mass consistent model application to the study of phenomenon in advance of sand towards the Algerian High Plains

For the study of the phenomenon of the Algerian High Plains turning into a desert, two approaches were used. The first consists of the processing of data measured on the level of weather stations located on the soil and the second by the use of a model allowing the interpolation and the extrapolation of data measured at 700 Hpa towards the soil, taking into account the terrain conditions. The two methods showed that the dominant winds are in the northern and western sectors, suggesting that the wind is not the principal factor in the progress of the sand towards north.     

Development of a new solar thermal engine system for circulating water for aeration

This paper presents a numerical study about the performance of a Beta Stirling solar thermal engine system. This system is composed of a solar collector box connected to a regenerator hydraulic system and a transmitting power system. The objective of the system is to offer a new alternative to help solving stagnant water pollution in hot countries like Thailand by circulating water in canals, lakes, ponds etc. for aeration using solar energy.The purpose of this study is to determine the power output and actual heat transfer on the performance of the solar thermal engine. The solar thermal engine is analyzed using a mathematical model based on the first law of thermodynamics for processes with finite speed, with particular attention to the energy balance at the receiver. The result of calculations showed that the regenerator volume and phase angle must be chosen carefully to fulfill the requirement that total fluid mass in the system is constant and to obtain maximum power output throughout the day.     

Composite short-side-chain PFSA electrolyte membranes containing selectively modified halloysite nanotubes (HNTs)

Aquivion membrane displays improved properties as compared to Nafion membrane, partly due to shorter side chains. However, some improvements are still necessary for proton exchange membrane fuel cell to operate at low relative humidity. To overcome this drawback, the addition of clay nanoparticle into the Aquivion matrix can be considered. In this study, different composite membranes have been prepared mixing short-side-chain PFSA (perfluorosulfonic acid) Aquivion and selectively modified halloysite nanotubes for PEMFC low relative humidity operation. Halloysites were grafted with fluorinated groups, sulfonated groups, or perfluoro-sulfonated groups on inner or outer surface of the tubes. The obtained composite membranes showed improved properties, especially higher water uptake associated with reduced swelling and better mechanical strength compared to pristine Aquivion membrane and commercially available Nafion HP used as reference. The best performance in this study was obtained with Aquivion loaded with 5 wt% of pretreated perfluoro-sulfonated halloysite. The composite membrane, referred to as Aq/pHNT-SF5, displayed the largest water uptake and proton conductivity among the panel of membranes tested. The chemical stability was not affected by the presence of halloysite in the Aquivion matrix.

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Environmental assessment of flue gas cleaning processes of municipal solid waste incinerators by means of the life cycle assessment approach

Life cycle assessment (LCA) is an environmental assessment tool generally applied to products but also to processes. Features of the LCA of processes are presented in this paper. This approach was used to compare two flue gas cleaning processes: the typical wet-type process and the new transported droplets column process. The LCA result shows that the global environmental burden is similar between the two processes, which confirms the viability of the transported droplets column. The distribution of the environmental burden, however, is different between the two processes. The weak points of the transported droplets column are the pollution transfer from air to water and a larger volume to stabilize. Its strong point: it is more efficient in capturing dust particles and toxic pollutants. This process could be improved from an environmental standpoint by adding an electrostatic filter upstream of the transported droplets column to capture the particles. The laboratory results of the transported droplets column need, however, to be confirmed at a larger scale.