1,207 research outputs found
Fuat Sezgin, Geschichte des arabischen Schrifttums. Band V : Mathematik, bis ca. 430 H.
No full textRashed Roshdi. Fuat Sezgin, Geschichte des arabischen Schrifttums. Band V : Mathematik, bis ca. 430 H.. In: Revue d'histoire des sciences, tome 29, n°2, 1976. pp. 183-184
Settlement in municipal solid waste landfills: II. Mathematical simulation
No full textThe biodegradation of organic matter in MSW landfills increases the void ratio and weakens the structural strength of the refuse within a landfill leading to a substantial loss of volume and settlement. Development of completed landfill sites which is highly desirable particularly in land-limited locations, is invariably hindered by these settlements. Estimating long term landfill settlements becomes an integral part towards final site closure and ultimate usage. The rate and magnitude of these settlements depend primarily on refuse composition and operational-management practices which affect bio-degradation and stabilization processes within landfills. Field scale experiments were conducted to measure refuse settlements rates under different operational management practices including leachate recirculation, addition of water, buffer and microbial seed. The effect of these practices on settlement rates and magnitudes is evaluated. The field test data are used to calibrate mathematical models that are traditionally used in soil consolidation. The models can be applied to simulate landfill settlement rates and correlate these rates to refuse biodegradation and stabilization processes within landfills. The present research work is presented in series of two papers:I. field scale experiments II. mathematical modeling of settlement behaviour
Polymer multimode waveguide optical and electronic PCB manufacturing
No full textThe paper describes the research in the £1.3 million IeMRC Integrated Optical and Electronic Interconnect PCB Manufacturing (OPCB) Flagship Project in which 8 companies and 3 universities carry out collaborative research and which was formed and is technically led by the author. The consortium’s research is aimed at investigating a range of fabrication techniques, some established and some novel, for fabricating polymer multimode waveguides from several polymers, some formulations of which are being developed within the project. The challenge is to develop low cost waveguide manufacturing techniques compatible with commercial PCB manufacturing and to reduce their alignment cost. The project aims to take the first steps in making this hybrid optical waveguide and electrical copper track printed circuit board disruptive technology widely available by establishing and incorporating waveguide design rules into commercial PCB layout software and transferring the technology for fabricating such boards to a commercial PCB manufacturer. To focus the research the project is designing an optical waveguide backplane to tight realistic constraints, using commercial layout software with the new optical design rules, for a demonstrator into which 4 daughter cards are plugged, each carrying an aggregate of 80 Gb/s data so that each waveguide carries 10 Gb/s
Before and After the Commentators: An Essay in Periodization.
No full textL'articolo considera il significato storico e filosofico dei commentatori neoplatonici di Aristotele. Gli autori situano il recente Sourcebook sui commentatori edito da Richard Sorbji in un contesto più ampio, che include il contributo dei commentatori nella formazione della filosofia tardo-antica e la loro posterità nella tradizione filosofica islamica. Dopo una sezione introduttiva (1) sullo stato attuale della ricerca in questo ambito, gli autori affrontano i temi seguenti: (2) Plotino, i commentatori e lo sviluppo del pensiero tardo antico; (3) il Sourcebook e la filosofia islamica. Riccardo Chiaradonna è co-autore della sezione (1) e autore della sezione (2), dove la ricezione dei trattati di scuola aristotelici è presentata come una caratteristica fondamentale nella transizione dalla filosofia post-ellenistica a quella tardo-antica. Plotino ha un ruolo cruciale in questo processo e l'assimilazione neoplatonica dei trattati di Aristotele non avrebbe avuto luoro senza il suo contributo.This article considers the historical and philosophical significance of the Neoplatonic commentators on Aristotle. The authors set Richard Sorabji's recent Sourcebook on the commentators within a wider backgroung, which covers the commentators' contribution in the shaping of late antique philosophy and their posterity in the Islamic philosophical tradition. After an introductory section (1) regarding the current status of research in this area, the authors tackle the following issues: (2) Plotinus, the commentators and the development of late antique thought; (3) the Sourcebook and Islamic Philosophy. Riccardo Chiaradonna is co-author of section (1) and author of section (2), where the reception of Aristotle's school treatises is set out as a key feature in the transition from Post Hellenistic to Late Antique philosophy. Plotinus has a pivotal position in this process and the Neoplatonic incorporation of Aristotle's treatises would have not taken place without Plotinus' contribution
Analysis of energy consumption in micro-drilling processes
No full textThe paper analyzes energy consumption as a performance indicator for micro-manufacturing. A comparative analysis between micro-EDM and ultrashort pulse laser drilling is performed on the basis of similar process outputs like drilled thickness of 350 μm, hole diameter of 180 ± 3 μm, drilling time, micro-hole shape and inner surface quality. Experimental data revealed that ultrashort pulse laser drilling enabled root mean squared surface roughness of about 100 nm in a drilling time of 2.5 s, whereas using a conventional micro-EDM drilling operation with a 10 s duration yielded surface roughness of 380 nm.
For ultrashort pulse laser ablation the specific energy consumption is increased, as the drilling time is decreased due to an increase of the adopted pulse energy up to 50 μJ but the surface roughness and the capability of obtaining very sharp edges remain unchanged. With a calculated energy intensity in the order of 1010 J/kg and a process rate in the order of 10−6 kg/h, ultrashort pulse laser drilling can be considered as a valid alternative from both technology point of view and specific energy consumption to similar drilling process, like micro-EDM which is characterized by a lower process rate and a higher energy intensity
Arabic offensive language on twitter: Analysis and experiments
No full textDetecting offensive language on Twitter has many applications ranging from detecting/predicting bullying to measuring polarization. In this paper, we focus on building a large Arabic offensive tweet dataset. We introduce a method for building a dataset that is not biased by topic, dialect, or target. We produce the largest Arabic dataset to date with special tags for vulgarity and hate speech. We thoroughly analyze the dataset to determine which topics, dialects, and gender are most associated with offensive tweets and how Arabic speakers use offensive language. Lastly, we conduct many experiments to produce strong results (F1 = 83.2) on the dataset using SOTA techniques
Antioxidant and antisteatotic activities of a new fucoidan extracted from ferula hermonis roots harvested on lebanese mountains
No full textFucoidan is a fucose-rich sulfated polysaccharide with attractive therapeutic potential due to a variety of biological activities, including antioxidant action. Fucoidan is typically found in the cell wall of marine brown algae, but extra-algal sources have also been discovered. In the present work, for the first time we extracted a water soluble fucoidan fraction from the roots of the terrestrial shrub Ferula hermonis. This fucoidan fraction was termed FUFe, and contained fucose, glucose, sulfate, smaller amounts of monosaccharides such as galactose and mannose, and a minor quantity of proteins. FUFe structural features were investigated by FTIR, 1H NMR and 13C NMR spectroscopy. The antioxidant property of FUFe was measured by DPPH, ABTS and FRAP assays, which revealed a high radical scavenging capacity that was confirmed in in vitro cellular models. In hepatic and endothelial cells, 50 μg/mL FUFe could reduce ROS production induced by intracellular lipid accumulation. Moreover, in hepatic cells FUFe exhibited a significant antisteatotic action, being able to reduce intracellular triglyceride content and to regulate the expression of key genes of hepatic lipid metabolism. Altogether, our results candidate FUFe as a possible bioactive compound against fatty liver disease and related vascular damage
Authigenic minerals from the Paola Ridge (southern Tyrrhenian Sea): Evidences of episodic methane seepage
No full textPaola Ridge, along the NW Calabrian margin (southern Tyrrhenian Sea), is one of the few reported deep sea sites of precipitation of authigenic carbonates in the Tyrrhenian Sea. Here, the changing composition of the seeping fluids and the dynamic nature of the seepage induced the precipitation of pyrite, siderite and other carbonate phases. The occurrence of this array of authigenic precipitates is thought to be related to fluctuation of the sulfate-methane transition zone (SMTZ). Concretions of authigenic minerals formed in the near sub-bottom sediments of the Paola Ridge were investigated for their geochemical and isotopic composition. These concretions were collected in an area characterized by the presence of two alleged mud volcanoes and three mud diapirs. The mud diapirs are dotted by pockmarks and dissected by normal faults, and are known for having been a site of fluid seepage for at least the past 40 kyrs. Present-day venting activity occurs alongside the two alleged mud volcanoes and is dominated by CO2-rich discharging fluids. This discover led us to question the hypothesis of the mud volcanoes and investigate the origin of the fluids in each different domed structure of the study area. In this study, we used stable isotopes (carbon and oxygen) of carbonates coupled with rare earth element (REE) composition of different carbonate and non-carbonate phases for tracing fluid composition and early diagenesis of authigenic precipitates. The analyses on authigenic precipitates were coupled with chemical investigation of venting gas and sea-water. Authigenic calcite/aragonite concretions, from surficial sediments on diapiric structures, have depleted 13C isotopic composition and slightly positive δ18O values. By contrast, siderite concretions, generally found within the first 6 m of sediments on the alleged mud volcanoes, yielded positive δ13C and δ18O values. The siderite REE pattern shows consistent LREE (light REE) fractionation, MREE (medium REE) enrichment and positive Gd and La anomalies. As shown by the REE distribution, the 13C-depleted composition and their association with chemosymbiotic fauna, calcite/aragonite precipitated at time of moderate to high methane flux close to the seafloor, under the influence of bottom seawater. Authigenic siderite, on the other hand, formed in the subseafloor, during periods of lower gas discharges under prolonged anoxic conditions within sediments in equilibrium with 13C-rich dissolved inorganic carbon (DIC) and 18O-rich water, likely related to methanogenesis and intermittent venting of deep-sourced CO2
Source misalignment in multimode polymer tapered waveguides for optical backplanes
No full textPolymer tapered multimode waveguides were modeled using the finite difference wide-angle beam propagation method to investigate whether tapered input waveguide couplers decreasing in width away from the waveguide entrance give improved tolerance to lateral misalignments of an optical source compared to straight waveguides and whether there is any effect on angular misalignment tolerance for use in optical backplane interconnections. Input tapered couplers having a larger entrance and tapering down in width do indeed improve the lateral misalignment tolerance compared to straight waveguides but do so at the expense of an increased loss. Tapers have no effect on angular tolerance for strongly driven vertical cavity surface-emitting laser (VCSEL) sources although they cause a loss of angular tolerance for single-mode fiber sources and VCSELs at low drive currents. (c) 2007 Society of Photo-Optical Instrumentation Engineers
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