Expanding cellular coverage via cell-edge deployment in heterogeneous networks: spectral efficiency and backhaul power consumption perspectives

Heterogeneous small-cell networks (HetNets) are considered to be a standard part of future mobile networks where operator/consumer deployed small-cells, such as femtocells, relays, and distributed antennas (DAs), complement the existing macrocell infrastructure. This article proposes the need-oriented deployment of smallcells and device-to-device (D2D) communication around the edge of the macrocell such that the small-cell base stations (SBSs) and D2D communication serve the cell-edge mobile users, thereby expanding the network coverage and capacity. In this context, we present competitive network configurations, namely, femto-on-edge, DA-onedge, relay-on-edge, and D2D-communication on- edge, where femto base stations, DA elements, relay base stations, and D2D communication, respectively, are deployed around the edge of the macrocell. The proposed deployments ensure performance gains in the network in terms of spectral efficiency and power consumption by facilitating the cell-edge mobile users with small-cells and D2D communication. In order to calibrate the impact of power consumption on system performance and network topology, this article discusses the detailed breakdown of the end-to-end power consumption, which includes backhaul, access, and aggregation network power consumptions. Several comparative simulation results quantify the improvements in spectral efficiency and power consumption of the D2D-communication-onedge configuration to establish a greener network over the other competitive configurations

Analytical Study of Environmental Impacts and Their Effects on Groundwater Hydrology

The hydrology of the groundwater is not just the science of subsurface water but also encompasses the rock strata and structure matrix in which it is contained. It also deals with the natural and man-made activities that affect the quality and quantity of subsurface water and physiology, geology, and minerology of the rock structure as well as the effects of the environment, climate, and other physical and natural forces trying to alter the subsurface water source in either way. Strategies for management and upkeep of groundwater as a resource are also discussed for sustainable and equitable usage by all stakeholders

Processing and application of polyolefin plastics

This thesis describes the manufacturing, processing and application of polyolefin thermoplastics. Polyolefins have become one of the most important kinds of plastics. Polyolefin resin represents about one third of all plastics sold and its application for films and containers dominate the packaging industry. The objective of this thesis is to present the various processing methods and application of polyolefin thermoplastics. Polyolefin is produced by several different processes. Conventional low density polyethylene is made by polymerizing ethylene at high pressure and high temperatures while high density polyethylene is polymerized at relatively low pressure and low temperatures. Generally all polyolefin possess excellent electrical properties, excellent resistance to water and moisture and good resistance to chemicals. They are translucent, light weight, tough and flexible material. This combination of properties makes them suitable for film, blow, and injection molded parts, flexible sheet and extruded profiles, and tubing

Corporate Governance for Banks in Pakistan: Recent Developments and Regional Comparisons

The emerging economies in the South Asian region have embarked on a bold reform process to develop the banking sector. This development has improved the transparency and accountability of the banking sector because these countries focused on ‘best practice’ corporate governance for banks. In view of a rapidly developing market with a slow pace of information dissemination, adverse selection and moral hazard problems are likely to be on the rise and may need a mechanism to train and discipline bank management. It was, therefore timely for the central banks in the region to introduce a ‘best practice’ for the banking system as a whole. This study provides a survey of recent developments in corporate governance of the banking sector in Pakistan and a comparison of similar developments in two other regional economies, namely, India and Bangladesh. In addition to a theoretical discussion on this issue, we also provide an overview of the banking sector restructuring and highlighting important features of the codes of corporate governance established by central banks in the sample countries. In conclusion, we present a comparison of the major differences in these measures across countries and comment on the pace of these developments.Corporate Governance, Banks, Pakistan

Gold cyanidation : gold associated with silver minerals embedded within base-metal sulphide matrices

Les problématiques dans le traitement des minerais aurifères deviennent de plus en plus significatives avec la déplétion des gisements à haute teneur autour du monde. L’or est trouvé principalement sous forme métallique dans la nature et est fréquemment associé avec des minéraux d’argent ou des sulfures métalliques. Dans la présente thèse, le rôle des minéraux d’argent sur la cyanuration de l’or au sein de sulfures métalliques est étudié en détail relativement aux interactions galvaniques et aux phénomènes de passivation de surface. Puisque les contacts galvaniques permanents naturellement présents à l’intérieur des grains des minéraux sont difficiles à répliquer en utilisant des montages standards d’électrodes à disques rotatifs ou de la pulpe de minerais riches en sulfures, une stratégie utilisant un réacteur à lit fixe (PBR) a été adoptée afin d’isoler et de quantifier les contributions des interactions galvaniques et des réactions de passivation sur les taux de lixiviation de l’or et de l’argent au sein de sulfures métalliques. Des mélanges d’or, de minéraux d’argent et d’autres sulfures métalliques ont été placés dans le réacteur à lit fixe afin de créer des contacts galvaniques inter-particules permanents parmi les constituants. La pyrite, la sphalérite et la stibnite ont été choisis comme sulfures métalliques modèles. De l’argent métallique (Ag), de l’acanthite Ag₂S) et de la pyrargyrite (Ag₃SbS₃) sont pour leur part les minéraux d’argent qui ont été étudiés. Les interactions galvaniques entre l’or, l’argent et la pyrite ainsi que la sphalérite ont résulté en un comportement complexe de la lixiviation de l’or et de l’argent sous l’impact direct des contacts galvaniques ainsi que sous l’impact des effets de passivation. Les minéraux d’argent ont pour leur part démontré un effet amoindrissant pour la lixiviation de l’or dans de la chalcopyrite et de la stibnite. Des stratégies ont été investiguées pour améliorer la cinétique de lixiviation de l’or en présence de minéraux d’argent et de sulfures métalliques. Des solutions de cyanure contant des sels de plomb ont augmenté la récupération de l’or et ont permis une neutralisation des effets négatifs issus de la présence des sulfures métalliques, particulièrement dans le cas de la chalcopyrite. De plus, l’addition de plomb a augmenté les cinétiques de lixiviation de l’or de manière significative pour l’or et l’argent associé à de la pyrite, de la chalcopyrite et de la sphalérite. Un prétraitement à l’aide d’une solution alcaline d’acétate de plomb a été étudié pour les mêmes couples de minéraux et il a été démontré que cette stratégie augmente la récupération de l’or dans le cas de la pyrite, de la chalcopyrite et de la sphalérite. D’autre part, la stibinite a démontré un effet net de réduction de la dissolution de l’or avec des minéraux d’argent. Des films recouvrant la surface des particules d’or dans le cas de la cyanuration de l’or en présence des sulfures métalliques ont aussi été observés dans le cas de la chalcopyrite et de la stibnite.Numerous non-idealities in gold processing are becoming increasingly significant with the depletion of free-milling oxide ores around the globe. Gold is mostly found in nature in metallic form and is associated with silver minerals and bae-metal sulphides. In the present thesis work, the role of silver minerals on gold cyanidation with base-metal sulphides was elucidated in detail on the relative importance of galvanic interactions and passivation phenomena. As the permanent galvanic contacts, inherently present within the ore grains, are hard to achieve between gold rotating disk electrode and slurried base-metal sulphide-rich ores, a packed-bed reactor (PBR) strategy was thus adopted to single out and quantify the virtual contributions of galvanic interaction and passivation effect on the gold and silver leaching rates during gold cyanidation with silver minerals and base-metal sulphides. The mixtures of gold, silver-minerals and sulphides were filled in the PBR to ensure the permanent particle-particle micro-electrical contacts among all ore constituents. Pyrite, chalcopyrite, sphalerite and stibnite were the sulphidic minerals investigated in the present gold-silver cyanidation study. Metallic silver (Ag), acanthite (Ag₂S) and pyrargyrite (Ag₃SbS₃), were the silver-minerals taken into account. Galvanic interactions were found to alleviate the leaching of gold and silver to various extents, for gold and silver minerals associated with pyrite and sphalerite, both under galvanic and passivation impact from the sulphide minerals. Silver minerals were found retarding to the gold leaching for chalcopyrite and stibnite minerals. Strategies were investigated to enhance the gold leaching kinetics in the presence of silver minerals and base-metal sulphides. Lead containing cyanide solution enhanced gold recovery and was found to neutralize significantly the negative effect of sulphidic minerals, particularly for chalcopyrite. Moreover, lead addition enhanced gold leaching kinetics significantly for gold and silver minerals associated with pyrite, chalcopyrite and sphalerite. Pre-treatment with alkaline lead acetate tested on sulphide associated mixtures of gold and silver minerals affirmed enhanced gold recovery in case of pyrite, chalcopyrite and sphalerite minerals. Stibnite found severely retarding towards gold dissolution with silver minerals. Surface obstructing films were observed on gold particles for gold cyanidation with silver minerals and base-metal sulphides in case of chalcopyrite and stibnite