Efficient Heuristic for Resource Allocation in Zero-forcing OFDMA-SDMA Systems with Minimum Rate Constraints

4G wireless access systems require high spectral efficiency to support the ever increasing number of users and data rates for real time applications. Multi-antenna OFDM-SDMA systems can provide the required high spectral efficiency and dynamic usage of the channel, but the resource allocation process becomes extremely complex because of the augmented degrees of freedom. In this paper, we propose two heuristics to solve the resource allocation problem that have very low computational complexity and give performances not far from the optimal. The proposed heuristics select a set of users for each subchannel, but contrary to the reported methods that solve the throughput maximization problem, our heuristics consider the set of real-time (RT) users to ensure that their minimum rate requirements are met. We compare the heuristics' performance against an upper bound and other methods proposed in the literature and find that they give a somewhat lower performance, but support a wider range of minimum rates while reducing the computational complexity. The gap between the objective achieved by the heuristics and the upper bound is not large. In our experiments this gap is 10.7% averaging over all performed numerical evaluations for all system configurations. The increase in the range of the supported minimum rates when compared with a method reported in the literature is 14.6% on average.Comment: 8 figure

The Effects of IFRS on Financial Ratios: Early Evidence in Canada

This paper provides preliminary evidence of the impact on financial ratios caused by the transition to International Financial Reporting Standards (IFRS) in Canada. The main features of IFRS are explained in the context of a shift from Canadian Generally Accepted Accounting Principles (GAAP) while the main differences between the two sets of rules are underscored – heavier reliance of IFRS on fair value accounting and comprehensive income, and the use of the entity theory for consolidation. The effects of IFRS on financial ratios in the areas of liquidity, leverage, coverage and profitability are discussed and verified using a sample cohort of early adopters in Canada. The preliminary evidence reveals significantly higher volatility to most of the ratios under IFRS when compared to those derived under pre-changeover Canadian GAAP. While the means and medians of IFRS ratios differ from the means and medians of the same ratios under pre-changeover Canadian GAAP, the differences are not statistically significant overall. However, important individual discrepancies are in some cases observed. Naturally, analysts using ratios for analytical purposes during the transition period need to be vigilant as ratios computed under IFRS are not directly comparable with those derived under pre-changeover Canadian GAAP. It is recommended that heightened attention be directed to the new feature – comprehensive income – which incorporates unrealized gains and losses that bypass the income statement. The suggested analytical tools best suited to mitigate the contributing effect include reliance on comprehensive-Return on Assets (ROA) and comprehensive-Return on Equity (ROE).IFRS, financial ratios, first application of IFRS

Wet air oxidation for industrial wastewater and sludge treatment: first results of a new research program in Quebec

Introduction Sub-critical water technologies, in particular wet air oxidation (WAO), have been developing across Europe in recent decades. This process is now used at the industrial scale for the effective treatment of wet organic material, mainly sludge from wastewater treatment plants (WWTP), and is done with energy self-sufficiency [1, 2]. In WAO, hot pressurised water (200-350 ˚C, 30-200 bars) is enriched with oxygen or air to initiate exothermic oxidation of organic material, mostly into CO2 and H2O. Since the operating temperature is much lower than typical incineration, no gaseous emissions of NOX, dioxins or furans are generated. Water is being kept in a liquid state due to high pressure, avoiding energy losses by vaporisation. These characteristics allow WAO to be a competitive and environmental friendly process for a variety of wet organic wastes and chemical effluents. However, WAO is still non-existent in the province of Quebec (Canada) and unknown to industries. In 2014, Centre de transfert technologique en écologie industrielle (CTTÉI), an applied research center in industrial ecology, acquired a WAO laboratory unit and launched the first research program in this field in the province of Quebec. This program, financed by NSERC (Natural Sciences and Engineering Research Council of Canada), Produits Chimiques Magnus and the City of Sorel-Tracy, aims to study the potential of this technology on various industrial wastes in Quebec and facilitate its transfer to industries. CTTÉI is also supported by European partners Innovation Fluides Supercritiques (IFS) and Aix-Marseille University. Please click Additional Files below to see the full abstract

GEOTHERMAL EXPLORATION IN MARTINIQUE BASED ON MAGNETO-TELLURIC AND CONTROLLED-SOURCE EM SURVEY

International audienceResistivity imaging is a key input in many geothermal exploration programs, and particularly in volcanic environment. It is assumed that resistivity variations allow imaging the caprock, but also hydrothermal weathering and preferential geothermal fluid flow. The latter is generally a brine which drastically decreases the electrical resistivity and the temperature increase also lowers resistivity. Several authors have described resistivity signatures for some geothermal reservoirs context. Magnetotelluric (MT) is generally used to image resistivity variations down to a relevant investigation depth of several kilometers. Within the framework of a global French program oriented towards the development of geothermal energy, Martinique Island (Lesser Antilles, France) has been extensively investigated (from 2012 to 2013) through an integrated multi-method approach, with the aim to define precisely the potential geothermal structures previously highlighted. Amongst the common investigation methods deployed, we carried out three magnetotelluric (MT) surveys located above three out of the most promising geothermal areas of Martinique, namely the Anses d'Arlet (focus of this presentation), the Montagne Pelée and the Pitons du Carbet prospects. Based on natural source signal, the quality of broad band MT data depends on the source activity (lightning strikes and sun) during the survey but also on the local noise conditions. In many cases, because industrial activities have been developed close to the geothermal resource, the noise conditions make it difficult to obtain reliable MT tensors and therefore a good resistivity distribution. A common way to improve the data quality is to record longer time series and to apply robust processing with remote reference including noise filtering