On enhancing reputation management using Peer-to-Peer interaction history

Cooperation incentive mechanisms are an essential ingredient to the success of Peer-to-Peer (P2P) systems as they restraint the phenomenon of free-riding. We introduce an enhancement on reputation-based cooperation incentives used by the eDonkey2000 (ED2K) P2P file sharing network. This enhancement, called History-based Reputation System (HRS), can achieve better detection and control of free-riders, and by doing so enhances the scalability and fairness of the P2P system. HRS does not need the help of dedicated servers and/or central authorities, thus avoiding a single-point of failure. In addition, simulation results show that HRS achieves higher average download rate and smaller average download time for altruistic peers in a file sharing P2P system.     

ORGANIC MATTER AS INDICATOR OF THE DEGREE OF METAMORPHISM OF THE CARBONIFEROUS ROCKS IN THE SOUTH WALES COALFIELDS

Isoreflectance maps of vitrinites in coals and phytoclasts (coaly inclusions) in the Coal Measures of S. Wales show a progressive increase in vitrinite reflectance with increase in coal rank and grade of metamorphism towards the anthracite area in the west, without significant variation in reflectances of coals with present depth. Differences between values of vitrinite reflectance in coals and phytoclasts in the same profile are recorded and attributed to variations in depositional environments, and to susceptibility to alteration of the host rocks. Spores in the Coal Measures are progressively carbonized (from golden brown to black) towards the west, and this is not a function of present depth of burial. Reflectance of vitrinites in coals, degree of spore carbonization and coal rank are used in definition of three different diagenetic zones in the coalfield. The Coal Measures could have acted as a source for accumulations of gas in the Permo-Triassic sequence of the south Irish Sea, if necessary geologic conditions are present. Burial metamorphism (application of Hilt's law) could have caused the coalification of S. Wales coals up to the high and medium volatile bituminous stages (up to the late diagenetic stage). A relationship is established between the lateral variation in coal rank in the coalfield and the regional variation in coal rank in the southern British Isles, where two regions of markedly different geothermal history are recognised. The Diagenetic Zone in the E and S parts of the coalfields marks the final stage in the thermal history of the cold region (the W margin of London Stable Massif), whilst the Anchimetamorphic Zone in the NW part (the anthracite area) represents the final stage in the thermal history of the hot region (the S margin of St. George's Land).
Phytoclasts and spores are recorded for the first time from the Dinantian massive limestones of S. Wales.     

THE DIAGENESIS OF RESERVOIR SANDS OF THE ZUBAIR FORMATION (EARLY CRETACEOUS), NORTHERN KUWAIT - ARABIAN GULF

A total of ten conventional core samples of the Lower Cretaceous Zubair Sandstone Formation, as encountered in the Raudhatain sabriyah oilfields of Kuwait have been studied by grain-size analysis and scanning electron microscope (SEM) examination. Diagenesis of the sandstone members, in the form of silica overgrowths in optical continuity with the detrital quartz grains and the formation of authigenic kaolinite, is indicated. Further studies will be required in order to establish a possible correlation among the reservoir properties, diagenetic changes and oil accumulation in the Zubair Formation examined in these two fields.     

Technique of multi-step concrete mixing

Multi-step concrete mixing techniques are used to improve the properties of cement paste, mortar and concrete. Different methods are followed in the USA, the UK, Russia, Canada, Belgium, Poland and Japan. The properties of multi-step mixing and conventional methods are compared.

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Resume On utilise les techniques de malaxage du béton en plusieurs étapes pour améliorer les propriétés de la pate de ciment, du mortier et du béton. On décrit un certain nombre de méthodes en usage aux Etats-Unis, en Royaume Uni, en Russie, Belgique, Japan, Pologne et au Canada. On compare les propriétés du mélange en plusieurs étapes avec les méthodes conventionnelles.

     

Steel/mortar interfaces: Microstructural features and mode of failure

The interfacial zone of segregation formed between mild steel and Portland cement pastes or mortars has been studied by scanning electron microscopy. It consists of a discontinous layer of polycrystalline portlandite which varies in thickness and contains inclusions of CSH gel. Tensile fracture in specimens of this sort occurs largely at the interface but, for similar test pieces produced from other types of metal, different failure characteristics and bond strengths are observed.     

Adsorptive removal of alizarin dye from wastewater using maghemite nanoadsorbents

ABSTRACT

This is an investigation of the adsorptive removal of anthraquinone dyes, resembled by Alizarin, by utilizing maghemite iron oxide (γ-Fe₂O₃) nanoparticles in aqueous media. The adsorption process was affected by several parameters such as solution pH, adsorbent amount, contact time, and temperature. After optimizing the parameters affecting the adsorption, the process was successful in removing Alizarin dye with an efficiency exceeding 95%. Best adsorption results were achieved at a pH of 11 and contact time of 60 min. The adsorption was shown to follow the Langmuir model suggesting a monolayer and homogeneous coverage. The maximum adsorption capacity (q_m ) was found to be 23.2 mg/g at pH = 11. A thermodynamic study showed that the adsorption process is exothermic and spontaneous at room temperature. The Gibbs free energy of adsorption (-6.79 kJ/mol) obtained in this study suggests a physisorption process. This finding has facilitated the regeneration of the Fe₂O₃ nanocatalyst. Both NaOH and HNO₃ at dilute levels were tested for the regeneration of the nanocatalyst. Regeneration with HNO₃ was successful up to four successive removal cycles with an efficiency >80%. Photodegradation experiments utilizing a UV light were also successful in maximizing the adsorption removal efficiency. A sorption mechanism based on the results obtained in this work is also proposed.     

A Formal Testing Model for Operating Room Control System Using Internet of Things

Technological advances in recent years have significantly changed the way an operating room works. This work aims to create a platform to solve the problems of operating room occupancy and prepare the rooms with an environment that is favorable for all operations. Using this system, a doctor can control all operation rooms, especially before an operation, and monitor their temperature and humidity to prepare for the operation. Also, in the event of a problem, an alert is sent to the nurse responsible for the room and medical stuff so that the problem can be resolved. The platform is tested using a Raspberry PI card and sensors. The sensors are connected to a cloud layer that collects and analyzes the temperature and humidity values obtained from the environment during an operation. The result of experimentations is visualized through a web application and an Android application. The platform also considers the security aspects such as authorization to access application functionalities for the Web and the mobile applications. We can also test and evaluate the system’s existing problems and vulnerabilities using the IEEE and owasp IoT standards. Finally, the proposed framework is extended with a model based testing technique that may be adopted for validating thesecurity aspects.