Effect of impeller on sinking and floating behavior of suspending particle materials in stirred tank: A computational fluid dynamics and factorial design study

The present study focuses upon the effect of the impeller on sinking and floating behavior of suspending particles in stirred tank reactor, employing computational fluid dynamics (CFD) simulation where factorial design is used to investigate the main and interaction effects of design parameters on the particle distribution performance of four typical impeller designs. Factorial design results show the effect of diameter and width of the impeller and off-bottom clearance on sinking particles is different from that of floating particles and regression equations for sinking particles and floating particles are achieved separately. Meanwhile, optimal equations which quantitatively reveal the effect of impeller factors on suspension quality and energy input is established for impeller improvement. Besides the development of computational models, the combination of CFD simulation with factorial design method provides a useful approach to gain insight into the suspension behavior of sinking and floating particles, also it guides to optimize the impeller design.     

Solar and wind energy potential and utilization in Pakistan

Pakistan needs substantial amount of energy to develop its industry and to increase the agricultural productivity. The available indigenous energy resources are limited. The only option which the country has to pursue is renewable energy. This paper identifies the potentials of solar and wind energy. The prime sites for wind are coastal area, arid zone and hill terrains. Solar energy is abundant over most part of the country, maximum being received over Quetta valley.     

Recent advances and developments in advanced green porous nanomaterial for sustainable energy storage application

Journal of Porous Materials - Compared with traditional battery and super capacitor materials, nanomaterials can significantly improve ion transport and electron conductivity. There are many...     

Development of Optical Code Division Multiple Access Based System Using Spectral Amplitude Coding via Fiber Bragg Gratings (FBGs)

Wireless Personal Communications - The multiple user’s based transmission systems are developed in the past using various multiple access techniques for fibre optic communications. Among...     

Framework for Effective Utilization of Distributed Scrum in Software Projects

There is an emerging interest in using agile methodologies in Global Software Development (GSD) to get the mutual benefits of both methods. Scrum is currently admired by many development teams as an agile most known methodology and considered adequate for collocated teams. At the same time, stakeholders in GSD are dispersed by geographical, temporal, and socio-cultural distances. Due to the controversial nature of Scrum and GSD, many significant challenges arise that might restrict the use of Scrum in GSD. We conducted a Systematic Literature Review (SLR) by following Kitchenham guidelines to identify the challenges that limit the use of Scrum in GSD and to explore the mitigation strategies adopted by practitioners to resolve the challenges. To validate our review findings, we conducted an industrial survey of 305 practitioners. The results of our study are consolidated into a research framework. The framework represents current best practices and recommendations to mitigate the identified distributed scrum challenges and is validated by five experts of distributed Scrum. Results of the expert review were found supportive, reflecting that the framework will help the stakeholders deliver sustainable products by effectively mitigating the identified challenges.     

Recent developments and progress of aerogel assisted environmental remediation: a review

Journal of Porous Materials - Aerogel is a special type of porous material with many outstanding physical and chemical properties, such as low density, high porosity, high surface area, and...     

环锭纺竹浆/棉混纺纱线的性能研究

为了探究竹浆/棉混纺纱线的最优混纺比,通过改变竹浆纤维含量,制备了具有相同线密度和捻度的竹浆/棉混纺纱线,测试了竹浆/棉混纺纱线的条干均匀度、表观形态结构及力学性能,并讨论了竹浆纤维含量对竹浆/棉混纺纱线条干均匀性和力学性能的影响.试验结果表明:当竹浆纤维含量分别为10％,20％和40％时,纱线的条干均匀度优于纯棉纱线,且竹浆纤维比例的增加有利于改善纱线的条干均匀度;当竹浆纤维含量低于10％时,纱线的断裂强度基本呈上升趋势,随着竹浆纤维含量的进一步提高,纱线的断裂强度呈较明显的下降趋势;从纱线外观质量、力学性能及成本综合评价,应选择竹浆纤维含量在10％.     

Mineralogical Characterization of Dilband Iron Ore Deposits of Balochistan, Pakistan

Summary  Dilband iron ore deposits, recently discovered in 1997 by Geological Survey of Pakistan (GSP) in Kalat Division Balochistan, Pakistan, is of major importance from a socio-economical point of view among the indigenous iron ore deposits discovered so far in Pakistan. In order to meet the requirements of Pakistan Steel Mills ore specification (i.e. 57–60 % Fe (min), 8.5 % SiO₂ (max), 0.5 % Al₂O₃ (max), 0.1 %P (max), and 0.05 % S), the ore requires an adequate concentration method. This calls for detailed characterization of process relevant minerals and their intergrowth. For this reason mineralogical, petrographic, and elemental analysis were performed using XRD, thin section and SEM with EDS, and XRF and Atomic Absorption Spectrometer techniques, respectively. Mineralogical study revealed that Dilband iron ore is mainly composed of 46.27 % hematite, 17.41 % quartz 14.47 % calcite, 9.24 % chlinochlore, 10.5 % kaolinite, and 1.75 % fluorapatite minerals. Atomic absorption analysis of different size fractions ranging from −600 μm down to −38 μm indicated that Dilband iron ore contains on average of 40.18 % Fe, 18.34 % SiO₂, 5.32 % Ca, and 2.262 % Al. Whereas average analysis of different size fractions on XRF indicated 44.3 % Fe, 20.4 % SiO₂, 8.8 % CaO, 6.35 % Al₂O₃, 1.08 % P₂O₅, and 0.065 % SO₃. Three types of iron stones namely hematiteooides, hematite-peloids, and hematite biosparite were identified from petrographic study. From the mineralogical and elemental analysis data finely dissemination of impurities specially quartz, alumina and phosphorous in hematite phase is conceived, suggesting that Dilband iron ore is not amenable to upgrade with conventional techniques.

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Mineralogische Beschreibung der Dilband-Eisenerzlagerst?tten in Balochistan, Pakistan

Zusammenfassung  Die Dilband-Eisenerzlagerst?tten, die erst 1997 vom geologischen Dienst Pakistans in Kalat, Distrikt Balochistan, Pakistan, entdeckt wurden, sind im Vergleich zu den bisher in Pakistan entdeckten Eisenerzlagerst?tten aus gesellschaftlicher und wirtschaftlicher Sicht von besonderer Bedeutung. Um die Qualit?tsanforderungen des nationalen pakistanischen Stahlherstellers Pakistan Steel Mills (PSM) (i.e. 57–60 % Fe(min), 8,5 % SiO₂ (max), 0,5 % Al₂O₃ (max), 0,1 %P (max) and 0,05 %S) zu erreichen, muss das Erz mit geeigneter Aufbereitungstechnik angereichert werden. Dies macht die Beurteilung des prozessrelevanten Mineralbestandes und der Verwachsung notwendig. Mineralogisch-petrographische sowie Elementanalysen wurden mittels R?ntgendiffraktometrie, Mikroskopie, Rasterelektronenmikroskop mit energiedispersivem Spektrometer sowie R?ntgenfluoreszenzanalytik und Atomabsorptionsspektroskopie durchgeführt. Mineralogische Untersuchungen ergaben, dass die untersuchten Proben haupts?chlich aus H?matit (46 %), Quarz (17 %), Kalzit (14,5 %), Klinochlor (9,2 %), Kaolinit (10,5 %) und Flurapatit (1,75 %) aufgebaut sind. AAS in Kornklassen des Zerkleinerungsproduktes <600 μm lieferte einen durchschnittlichen Eisengehalt von 40,2 % bei 18,3 % SiO₂, 5,3 % Ca und 2,62 % Al. Demgegenüber stehen 44,3 % Fe, 20,4 % SiO₂, 8,8 % CaO, 6,35 % Al₂O₃ und 1,08 % P₂O₅ aus der R?ntgenfluoreszenzanalyse. Drei Typen von Eisensteinvariet?ten, n?mlich H?matit-Ooide, H?matit-Peloide und H?matit-Biosparit, konnten identifiziert werden. Aus den mineralogischen Untersuchungen, kombiniert mit jenen der Elementanalyse, lassen sich feinste Verteilung von Quarz-, Aluminium- und Phosphorverunreinigungen in den H?matit-Aggregaten ableiten, was zu dem Schluss führt, dass die Dilband-Eisenerze für konventionelle Aufbereitungstechnik nicht geeignet sind.

     

Towards Security of GSM Voice Communication

Wireless Personal Communications - Global system for mobile communication (GSM) is widely used digital mobile service around the world. Although GSM was designed as a secure wireless system, it is...