Energy and Throughput Optimization for Relay Based Heterogeneous Networks

International audienceHigh data rate is a challenge for the next generation cellular networks. This objective needs a significant densification of relay nodes within macro cell. In the LTE-Advanced network, multi-hop relaying has been taken as a promising key technique to provide high throughput to the users and to improve the area coverage. Besides, minimizing the energy consumption and electromagnetic pollution is an economic challenge for the operators. This paper is focused on relay based heterogeneous cellular network like LTE-Advanced. We investigate the problem of throughput and energy consumption optimization. Our contributions are two-fold. First, we develop an optimization tool to calculate an optimal offline configuration of heterogeneous cellular network that maximizes the network capacity with low energy consumption. Second, we highlight a significant gain due to the deployment of relay nodes and we investigate the energy- capacity tradeoff

SATDBailiff- Mining and Tracking Self-Admitted Technical Debt

Self-Admitted Technical Debt (SATD) is a metaphorical concept to describe the self-documented addition of technical debt to a software project in the form of source code comments. SATD can linger in projects and degrade source-code quality, but it can also be more visible than unintentionally added or undocumented technical debt. Understanding the implications of adding SATD to a software project is important because developers can benefit from a better understanding of the quality trade-offs they are making. However, empirical studies, analyzing the survivability and removal of SATD comments, are challenged by potential code changes or SATD comment updates that may interfere with properly tracking their appearance, existence, and removal. In this paper, we propose SATDBailiff, a tool that uses an existing state-of-the-art SATD detection tool, to identify SATD in method comments, then properly track their lifespan. SATDBailiff is given as input links to open source projects, and its output is a list of all identified SATDs, and for each detected SATD, SATDBailiff reports all its associated changes, including any updates to its text, all the way to reporting its removal. The goal of SATDBailiff is to aid researchers and practitioners in better tracking SATDs instances, and providing them with a reliable tool that can be easily extended. SATDBailiff was validated using a dataset of previously detected and manually validated SATD instances. SATDBailiff is publicly available as an open source, along with the manual analysis of SATD instances associated with its validation, on the project website

Comparative Study of Different Active Control Systems of High Rise Buildings under Seismic Excitation

Large number of active vibration control systems existing in the literature has brought lot of confusion for engineers and junior researchers. This study deals with the comparison of different active control systems of a 20-storey building under seismic excitation for three control devices: Active Mass Damper (AMD), Active Bracing System (ABS) and Connected Building Control (CBC). Two different control configurations are considered to add active damping to the building. The first one employs force actuator and displacement sensor and is examined with first and second order Positive Position Feedback, Lead compensators and Direct Velocity Feedback. The second configuration employs a displacement actuator collocated with a force sensor and an Integral Force Feedback control law. A total number of 15 control cases are compared from the point of view of stability, robustness, performance and control effort

Detecting the existence of gene flow between Spanish and North African goats through a coalescent approach

Human-driven migrations are one of the main processes shaping the genetic diversity and population structure of domestic species. However, their magnitude and direction have been rarely analysed in a statistical framework. We aimed to estimate the impact of migration on the population structure of Spanish and African goats. To achieve this goal, we analysed a dataset of 1,472 individuals typed with 23 microsatellites. Population structure of African and Spanish goats was moderate (mean FST=0.07), with the exception of the Canarian and South African breeds that displayed a significant differentiation when compared to goats from North Africa and Nigeria. Measurement of gene flow with Migrate-n and IMa coalescent genealogy samplers supported the existence of a bidirectional gene flow between African and Spanish goats. Moreover, IMa estimates of the effective number of migrants were remarkably lower than those calculated with Migrate-n and classical approaches. Such discrepancies suggest that recent divergence, rather than extensive gene flow, is the main cause of the weak population structure observed in caprine breeds.

Application of three cathodes reactor for stream reforming of propane at atmospheric pressure

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Syngas Production from Propane Using Atmospheric Non-thermal Plasma

International audiencePropane steam reforming using a sliding discharge reactor was investigated under atmospheric pressure and low temperature (420 K). Non-thermal plasma steam reforming proceeded efficiently and hydrogen was formed as a main product (H2 concentration up to 50%). By-products (C2-hydrocarbons, methane, carbon dioxide) were measured with concentrations lower than 6%. The mean electrical power injected in the discharge is less than 2 kW. The process efficiency is described in terms of propane conversion rate, steam reforming and cracking selectivity, as well as by-products production. Chemical processes modelling based on classical thermodynamic equilibrium reactor is also proposed. Calculated data fit quiet well experimental results and indicate that the improvement of C3H8 conversion and then H2 production can be achieved by increasing the gas fraction through the discharge. By improving the reactor design, the non-thermal plasma has a potential for being an effective way for supplying hydrogen or synthesis gas

Daily and seasonal time partitioning in surface activity of Porcellio albinus (Isopoda, Oniscidea) in the arid region of Zarat (Gabes, Tunisia)

The terrestrial isopod Porcellio albinus is a burrowing species, dwelling in the desert of south Tunisia. Field studies were carried out in the coastal area of Zarat, Tunisia, to examine the surface activity rhythm of P. albinus in relation to daily and seasonal variations in environmental conditions. The activity of P. albinus was followed once a month, from November 2012 through October 2013. Hourly capture frequency was compared across the different seasons of the year. Porcellio albinus is a strictly nocturnal species showing a nycthemeral rhythm regulated by the rhythmic and natural variations of the duration of the dark period. A positive correlation is observed between the circadian rhythm of the locomotor activity of the species and the duration of the dark period outside its burrow, P. albinus has a single daily activity peak. Individuals concentrated their activity in the first part of the night in winter and in the second part in summer. This peak is more spread out in spring and autumn. The differences in the activity rhythm of P. albinus between different seasons may be determined by two important factors, namely temperature and the length of the dark period

CO2 Reforming of CH4 in a non thermal plasma reactor at atmospheric pressure

International audienceHydrogen-rich gas can be efficiently produced in compact plasma reformers by the conversion of a variety of hydrocarbon fuels including natural gas and gasoline. This article describes a first approach in non thermal plasma reforming of methane with carbon dioxide. Experiments have been carried out in a compact device operating at low consumed power (100 - 200 W). Experiments demonstrated clearly the plasma ability to convert CO2 and CH4. A high level of hydrogen was obtained ([H2] up to 25 %). System efficiency was investigated as a term of both CO2 and CH4 conversion and syngas productio