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The isotopic composition of water in Earth’s oceans is challenging to recreate using a plausible mixture of known extraterrestrial sources such as asteroids—an additional isotopically light reservoir is required. The Sun’s solar wind could provide an answer to balance Earth’s water budget. We used atom probe tomography to directly observe an average ~1 mol% enrichment in water and hydroxyls in the solar-wind-irradiated rim of an olivine grain from the S-type asteroid Itokawa. We also experimentally confirm that H+ irradiation of silicate mineral surfaces produces water molecules. These results suggest that the Itokawa regolith could contain ~20 l m−3 of solar-wind-derived water and that such water reservoirs are probably ubiquitous on airless worlds throughout our Galaxy. The production of this isotopically light water reservoir by solar wind implantation into fine-grained silicates may have been a particularly important process in the early Solar System, potentially providing a means to recreate Earth’s current water isotope ratios. Water and hydroxyl enrichment in the solar-wind-irradiated rim of an olivine grain from asteroid Itokawa suggests that its regolith could contain ~20 l m−3 of water from solar wind—a potential water source for airless planetary bodies.

Desirable ripened quality banana fruits are important for the consumer acceptability. Banana cv. Amritasagar was treated with different ripening agents like control (R1), RipestuffTM @ 42 mg/10 mL water (R2), RipestuffTM @ 84 mg/10 mL water (R3), Ethephone @ 200 ppm (R4) and Ethephone @ 400 ppm (R5); and storage durations were 24 h (H1), 48 h (H2), 72 h (H3), and 96 h (H4). The two factors experiment was conducted with complete randomized design with three replications. Fruits were placed in container (RFL). With the progress of storage duration quality parameters like weight loss (%), peel color, pulp to peel ratio, softness, total soluble solids (TSS), and pH were recorded. Fruits treated with R3 and R5 produced uniform yellow color and the highest softness at 96 h. Whereas banana fruits treated with R2 developed peel colour and softness a bit slower compared to other treatments; and untreated fruits (control) were hard, poor in color and quality, and were not suitable for consumption at 96 h. The highest TSS (%) were found at 72 h treated with R5 and at 96 h with R5 including R3, and R4 showed the mostly similar TSS (%). Thus, RipestuffTM @ 84 mg/10 mL water (R3) and ethephon @ 400 ppm (R5) can be used maintaining quality and ripening banana for better price of banana growers and traders through avail it at earlier marketing and reduced postharvest loss.

Integrated farming system is a very effective tool for improving rural economy. Our present study was carried out in different pond dykes of Dumuria upazila of Khulna district, Bangladesh to investigate the effect of different fish pond sediments on growth, yield and subsequently analyze the nutritional quality of Indian spinach. The experiment consisted of two factors viz., pond types (P) (three different ponds growing different fish species: P1 = prawn and carp, P2 = prawn and mola, and P3=prawn, mola and carp) and each pond was cultivated with different fish species with different population densities); and pond sediments (M) (three levels: M1 = pond dyke soil, M2 =50% pond mud and 50% pond dyke soil, and M3 =100% pond mud). Physical and chemical properties of three ponds dyke soil as well as sediments were analyzed. Parameters studied on Indian spinach were growth, yield and nutritional qualities. Pond sediments were better quality due to well decomposition and microbial activity of sediments compared to dyke soil of ponds. Organic matter of pond sediment was 2.79 (P3) and EC was 790 (µc/cm). Plant height was varied from 10 to 19% due to the ponds type and sediment effects. Mostly, the plant growth was found better under the supplement of 100% pond sediments compared to dyke soil (M1) and mixed soil (M2). The highest yield was found in P3M3 and it was varied from 20 to 25%. Minerals like Ca (%), P (%), and S (mg/100g) were found statistically significantly higher in P2M3 compared to other treatments combinations. Nutrition like Vit A and Vit C were the highest (81.33 µg/100 g and 106.14 mg/100 g, respectively) found significantly higher in P2M3. Therefore, the pond mud (50% and 100%) can be used to increase the yield and nutrient uptake by the crop which can facilitate to reduce eutrophication and fertilizer for the better environment.

Welding processes offer a unique capability with a wide range of applications in industries. In recent times, welding has established itself as a tool for large scale additive manufacturing. In general, the quality and repeatability assurance for welding and specifically for additive manufacturing necessitates integrating process monitoring techniques with existing welding and additive manufacturing processes. The process-specific signals such as welding current fluctuations, temperature, and acoustic, generated during the welding operations, make them a suitable candidate for digitization. This chapter comprehensively describes the process monitoring techniques relevant to welding and additive manufacturing. Firstly, various sensors used during welding are described for their construction and working. Subsequently, specific applications of the sensors in digitizing the welding processes are presented.

The present research is aimed to identify the barriers in implementation of building information modelling (BIM) practices and challenges in construction industry in Qatar. Construction industry has been one of the lowest performing industries around the world. Recent growth in infrastructure projects in the past three decades has led to criticism of many problems. In view of improving the image of the industry, most commonly criticized issues are lack of innovation, industry wide fragmentation and low performance in delivery of projects. A collaborative working environment is required to solve these issues. In the past few years, development and use of information technology in AEC industry has increased to support the requirement of an integrated working environment. With revolution in use of technology, BIM seems to offer solution to most problems faced by the industry. BIM presents computer aided process to manage entire construction project from design phase to disposal of the built structure. Construction boards and private market forces in US and UK have reported low awareness and implementation about BIM. Recent improvements have not achieved the required level of deployment. Construction industry in Qatar faces similar issues in dealing with upsurge of infrastructure projects. Construction sector in Europe, US, UK and Singapore after witnessing the advantages of BIM started pushing for higher implementation. Expected use of BIM in Qatar will be less than European, US and UK markets at government level. As BIM offers solution to the issues faced by construction industry in Qatar, it will be beneficial to examine current status of implementation, barriers and challenges faced by the construction sector in its implementation in Qatar.

The Hall–Petch relation has long been used to relate the yield strength of a metal to its grain sizes in which the effectiveness of grain size strengthening in the metal is dictated by the Hall–Petch coefficient (slope). Therefore, understanding the microstructural dependence of the Hall–Petch slope would be very useful in designing new high-strength ultrafine grained (UFG) metallic materials. In this study, we investigated the microstructural factors affecting the Hall–Petch slope in UFG Al-Mg alloys with an average grain size range from 374 to 639 nm and different Mg contents of 0, 2.5, 5, and 7.5 at. pct. The rods prepared by extrusion of mechanically alloyed powder compacts were annealed for 5 hours at 380 °C, 420 °C, and 500 °C respectively followed by water quenching to produce the alloy samples in this study. The measured Hall–Petch slopes of the samples were found to increase with increasing Mg content and had higher values than those previously reported for Al(Mg) solid solutions with Mg concentrations comparable to the Mg contents in this study. Analysis of X-ray diffraction, transmission electron microscopy, and atom probe tomography experimental data as well as strengthening mechanisms demonstrates that the formation of nanoscale MgO dispersions plays a major role in the improved Hall–Petch slope observed in Al-Mg alloys.

The plastic anisotropies of two hot-rolled Lean Duplex Stainless Steels (commercially known as LDX 2101 and LDX 2404) were investigated by applying compressive strains, at 10−3 s−1 rate, along the rolling- and transverse-directions (RD and TD). The microstructural changes were elucidated by Electron Backscatter Diffraction (EBSD) as a function of strain level and loading direction. In both alloy grades, the austenite phase shows a weaker texture development than the ferrite phase; the later develops {001} and {110} textures in LDX 2101 and LDX 2404 alloys, respectively. Also, in both alloys, the yield stress along the TD is larger by 10% than along the RD. Anisotropies are also detected in the rate of property changes with deformations; after 30% true strain, the flow stress along the RD in LDX 2101 alloy starts exceeding the stress along the TD. Microstructural studies indicate that the load partitioning, grains shape, phase boundaries and austenite to martensite phase transformations are the origins of the anisotropic phenomena in LDX 2101 alloy, whereas the crystallographic texture of ferrite phase, phase boundaries and load partitioning are the plausible origins of plastic anisotropies in LDX 2404 alloy.

Acid mine drainage (AMD) is a serious environmental issue associated with mining due to its acidic pH and potentially toxic elements (PTE) content. This study investigated the performance of the Fe-Al bimetallic particles for the treatment of combined AMD-gold processing effluents. Batch experiments were conducted in order to eliminate potentially toxic elements (including Hg, As, Cu, Pb, Ni, Zn, and Mn) from a simulated waste solution at various bimetal dosages (5, 10, and 20 g/L) and time intervals (0 to 90 min). The findings show that metal ions with greater electrode potentials than Fe and Al have higher affinities for electrons released from the bimetal. Therefore, a high removal (&gt, 95%) was obtained for Hg, As, Cu, and Pb using 20 g/L bimetal in 90 min. Higher uptakes of Hg, As, Cu, and Pb than Ni, Zn, and Mn also suggest that electrochemical reduction and adsorption by Fe-Al (oxy) hydroxides as the primary and secondary removal mechanisms, respectively. The total Al3+ dissolution in the experiments with a higher bimetal content (10 and 20 g/L) were insignificant, while a high release of Fe ions was recorded for various bimetal dosages. Although the secondary Fe pollution can be considered as a drawback of using the Fe-Al bimetal, this issue can be tackled by a simple neutralization and Fe precipitation process. A rapid increase in the solution pH (initial pH 2 to &gt, 5 in 90 min) was also observed, which means that bimetallic particles can act as a neutralizing agent in AMD treatment system and promote the precipitation of the dissolved metals. The presence of chloride ions in the system may cause akaganeite formation, which has shown a high removal capacity for PTE. Moreover, nitrate ions may affect the process by competing for the released electrons from the bimetal owing to their higher electrode potential than the metals. Finally, the Fe-Al bimetallic material showed promising results for AMD remediation by electrochemical reduction of PTE content, as well as acid-neutralization/metal precipitation.

Coating rollers are widely popular in structural painting, in comparison with brushes and sprayers, due to thicker paint layer, better color consistency, and effortless customizability of holder frame and naps. In this paper, we introduce a cost-effective method to employ a general purpose robot (Sawyer, Rethink Robotics) for autonomous coating. To sense the position and the shape of the target object to be coated, the robot is combined with an RGB-Depth camera. The combined system autonomously recognizes the number of faces of the object as well as their position and surface normal. Unlike related work based on two-dimensional RGB-based image processing, all the analyses and algorithms here employ three-dimensional point cloud data (PCD). The object model learned from the PCD is then autonomously analyzed to achieve optimal motion planning to avoid collision between the robot arm and the object. To achieve human-level performance in terms of the quality of coating using the bare minimum ingredients, a combination of our own passive and builtin active impedance control is implemented. The former is realized by installing an ultrasonic sensor at the end-effector of robot working with a customized compliant mass-spring-damper roller to keep a precise distance between the end-effector and surface to be coated, maintaining a fixed force. Altogether, the control approach mimics human painting as evidenced by experimental measurements on the thickness of the coating. Coating on two different polyhedral objects is also demonstrated to test the overall method.

Pulse shaping techniques are an integral component of designing and executing valid Split-hopkinson pressure bar (SHPB) experiments. Proper pulse shaping is vital for achieving stress equilibrium and a constant strain rate within the dynamically tested sample. A systematic method based on two-dimensional finite element (FE) analysis was developed to design an optimized single material pulse shaper for SHPB testing of two stainless steel alloys. The tested alloys exhibit high strain-hardening, but have significantly different mechanical properties: Lean Duplex Stainless Steel 2101 (LDSS 2101) and austenitic stainless steel 316L. Results show that pulse shapers made of LDSS 2101 are capable of satisfying stress equilibrium and constant strain rate conditions for the studied materials at different strain rates regimes. The outlined FE analysis workflow is an effective approach to define the optimal dimensions of pulse shapers without the need for costly pulse-shaper-development experimental trials.

Tribo-electrochemical behavior of a high chromium white cast iron (high-Cr WCI) used in, e.g., slurry pumps in mining and mineral processing applications, was investigated using a combination of electrochemical techniques, including zero resistance amperometry as well as potentiostatic and potentiodynamic polarisation. The effects of third body particles angularity on the localised tribocorrosion response of the cast alloy was studied during and post abrasion-corrosion by round ceramic beads and semi-angular silica sand particles. Advanced characterization methods such as electron backscatter diffraction and focused-ion beam cross-sectioning of affected areas were also employed to understand the wear and corrosion interactive actions. It was found that in chloride-free solutions, the behavior of high-Cr WCI resembled that of the austenitic 316 SS studied before. In contrast, in chloride-containing electrolytes, the semi-angular silica sand particles increased interfacial (carbide/matrix) localised corrosion susceptibility during and post-abrasion as indicated by the stark increase in anodic current and the morphology of the attack. Semi-angular silica sand abrasives had a greater adverse impact on post-abrasion interfacial corrosion vulnerability, compared to round ceramic beads. The complex behavior observed indicates that any material developed for tribocorrosive conditions must account for the particles angularity and their subsequent effects on localised corrosion.

Hydroxypropyl methylcellulose acetate succinate (HPMCAS) has been widely used in amorphous solid dispersions and as an enteric coating polymer. Under aqueous coating conditions and at elevated coating temperatures, HPMCAS particles tend to aggregate and clog the spray-nozzle, hence interrupting the coating process. This research focused on how plasticizers and surfactants, excipients used for aqueous coating, affect the properties and stability of HPMCAS. This information would be useful in identifying suitable excipients for developing a stable HPMCAS aqueous enteric coating formulation. Triethyl citrate was found to be the most compatible plasticizer with HPMCAS, and displayed suitable thermal and mechanical properties. PEG 4000, the co-plasticizer, provided dispersion stability by yielding a dispersible sediment without aggregation at the elevated processing temperatures. Zeta potential measurements indicated sodium lauryl sulfate (SLS) could be used as a potential stabilizing agent at concentrations above its critical micelle concentration (CMC). This study facilitated the understanding of the HPMCAS aggregation mechanism, in addition to identifying suitable stabilizing agents. These stabilizing excipients could potentially be used to develop a stable aqueous coating formulation that does not exhibit polymer aggregation and nozzle clogging during the coating process.

With the impetus for less reliance on fossil fuels and an increasing demand for environmentally friendly energy materials, lithium is emerging as an important material of the future. The ability to extract lithium from ores economically is essential. However, a comprehensive understanding of the deportment of lithium and associated minerals in some ore bodies is limited. A combination of analytical microscopy and mass spectrometry techniques has been used to allow detection and characterisation of different lithium minerals in three micaceous Li-bearing ores. To quantify the different Li-bearing ore minerals, the chemistry and structural characteristics of a suite of lithium mineral specimens were first examined. The micas can be classified and grouped based on their compositions (Al/Si ratio; F, Na content) and used to distinguish different micas with different lithium grades. Micas exist as different polymorphs that are generally related to composition and also geological environment. The mineralogy, mineral associations and liberation characteristics of both ore-bearing and gangue minerals were characterised using automated mineralogy techniques and the Li content and elemental distribution within minerals defined using instrumentation with secondary mass spectrometry capabilities. The majority of lithium in the ore samples (1.2–1.5% Li) examined is associated with lepidolite or zinnwaldite particle compositions which are made up of Li muscovite, trilithionite and polylithionite grains. The morphology of the Li-bearing micas varies in different deposits. The gangue materials are predominately quartz and albite and make up ≤20 w% of the sample. Only minor amounts (∼1%) of other Li-bearing minerals (e.g. spodumene, elbaite, beryl) were observed in these samples. The Ta grade associated with minerals rynersonite and columbite-tantalite in some samples may be economic. The majority of the Li mica particles were liberated from the major gangue minerals under the conditions used to treat and screen samples to pass a 4 mm sieve. Further grinding will be required to breakup and expose fine grains of Li muscovite, polylithionite, and trilithionite, for further treatment to extract Li. The processes used to breakdown the micas to extract Li will also require stabilising and removal of F, Fe, Al, Mn and monovalent ions K and Na from process streams. The high concentration of Rb (0.9–3.6 wt%) and Cs (0.1–0.8 wt%) make mica a favourable resource for these elements and they can ultimately be recovered along with Li.

It is very important that the medical physicists working in hospitals need to be clinically trained.Bangladesh was the first RCA member to implement clinical training programme based on the guide-book for medical physicists specializing in nuclear medicine developed by International Atomic Energy Agency. A National Program was established and Bangladesh Medical Physics Association agreed to be the Professional Body for accreditation. The 2 years pilot to test the effectiveness of the guidebook was successfully finished. The Clinical Training for medical physicists specializing in nuclear medicine improved the capabilities of the Physicits’. A sustainable accreditation structure is in place. The objective of the program was to set up an infrastructure to operate an independent and sustainable accreditation programme that is recognized by all in Bangladesh and to test out the effectiveness of the guidebook in providing clinical training to medical physicists specializing in nuclear medicine.Bangladesh J. Nuclear Med. 18(1): 69-72, January 2015

Body-centred cubic magnesium-lithium-aluminium-base alloys are the lightest of all the structural alloys, with recently developed alloy compositions showing a unique multi-dimensional property profile. By hitherto unrecognised mechanisms, such alloys also exhibit exceptional immediate strengthening after solution treatment and water quenching, but strength eventually decreases during prolonged low temperature ageing. We show that such phenomena are due to the precipitation of semi-coherent D03-Mg3Al nanoparticles during rapid cooling followed by gradual coarsening and subsequent loss of coherency. Physical explanation of these phenomena allowed the creation of an exceptionally low-density alloy that is also structurally stable by controlling the lattice mismatch and volume fraction of the Mg3Al nanoparticles. The outcome is one of highest specific-strength engineering alloys ever developed., Solution treatment and quenching can strengthen magnesium-lithium-aluminium alloys, but this strength decreases with ageing. Here, the authors show this is due to semi-coherent nanoparticle precipitation followed by coarsening, and control the lattice mismatch to stabilise the microstructure.

A sequence of cyclic annealing experiments was performed to trace the growth of secondary grains after primary recrystallization in a two-pass cold rolled Fe-3.5%Si steel. By using electron backscattered diffraction (EBSD), the development of grain growth and texture in the early stages of secondary growth in as-received and annealed samples was examined. Annealing was performed at 900 °C for 3, 6 and 15 min. During the early stages of secondary growth, it was observed that Goss grains and other oriented grains can grow at the expense of their surrounding matrix grains. This growth is likely to be determined by particle dissolution at their boundaries which, hence, affects their ability to break away from pinning. It is shown that the presence of Σ5 and Σ9 CSL boundaries that surround Goss grains, size advantage in the as-received sample, texture sharpness and the presence of Goss grain colonies do not guarantee Goss grains to successfully grow at this stage of annealing.

This paper describes the changes in microstructures and their effects on property degradations in an environmentally friendly eutectic Sn0.7Cu (wt.%) solder alloy when subjected to harsh service conditions. A thorough microscopy investigation was conducted by scanning electron microscopy (SEM), electron backscattered diffraction (EBSD) and diffraction analysis with transmission electron microscopy (TEM). In the as-received alloy Cu6Sn5 intermetallic compound (IMC) particles are dispersed in the grain interiors and grain boundaries of β-Sn matrix. When the alloy was exposed for 60 days at 150 °C, the size of Cu6Sn5 IMC particles and Sn matrix grains were increased significantly. As a result the mechanical reliability of electronic interconnections turned inferior. This was confirmed by measuring a range of electrical and mechanical properties that include electrical resistivity, Young's moduli, shear moduli, microhardness and nano indentation creep behaviour. A comparison between the as-received and age-treated alloy shows that the degradation in Young's and shear moduli was about 10.6 and 9.9%, respectively, and that in hardness was about 25%. However the age treatment improved the damping property of the alloy. Keywords: Lead-free solder, Microstructure, Mechanical properties, Intermetallic compound

The reverse engineering (RE) of electronic chips and systems can be used with honest and dishonest intentions. To inhibit RE for those with dishonest intentions (e.g., piracy and counterfeiting), it is important that the community is aware of the state-of-the-art capabilities available to attackers today. In this article, we will be presenting a survey of RE and anti-RE techniques on the chip, board, and system levels. We also highlight the current challenges and limitations of anti-RE and the research needed to overcome them. This survey should be of interest to both governmental and industrial bodies whose critical systems and intellectual property (IP) require protection from foreign enemies and counterfeiters who possess advanced RE capabilities.

The paper investigates process–structure–property interconnection in anti-phase synchronised twin-wire gas metal arc welded low carbon steel samples wherein process variation is achieved by using similar and dissimilar currents and diameters at lead and trail wires. Scanning electron microscopy and microhardness measurements are used as characterisation techniques. The investigation offers new observations on heat generation and distribution in twin-wire welding that affect weld bead and microstructure formation due to changes in arc phenomenon and molten metal flow in weld pool. Use of dissimilar currents facilitates effective utilisation of heat. The two-stage arcing in twin-wire welding facilitates slow heating and cooling that leads to weld metal and heat affected zone softening. A combination of polygonal ferrite, pearlite and bainite with varying compositions is observed across the weldment. A higher current value and larger wire diameter at the lead wire leads to coarsening of the grains thereby re...

Availability of N, P and other trace metals in municipal wastewater (MWW) makes it very attractive to produce microalgae biomass using MWW. Although limited organic carbon is available in MWW, supplementing flue gas as CO2 sources may enhance both the biomass production and recycling of nutrients. Five microalgae strains were grown in the primary effluent of MWW, in a small-scale indoor experiment, to compare their nitrogen and phosphorus recovery abilities. From this study, two potential strains (Chlorella sp., and Scenedesmus sp.) were selected for the large-scale (i.e., 200 L) outdoor experiment. Each of these strains was grown in four different conditions: (1) MWW without any CO2 source, (2) MWW with pure CO2, (3) MWW with simulated flue gas (SFG), and (4) modified BG-11 medium with pure CO2. For both strains, injection of either CO2 or SFG in the MWW cultures resulted in faster growth rates, and higher biomass productivities compared to cultures that did not receive CO2 or SFG. Furthermore, recovery of TN from the MWW was ≥ 95% for the microalgae cultures that received either CO2 or SFG; however, in all cases, phosphorus recovery was less than 15% of the initial concentration. Both the MWW grown microalgae biomass (MWGMB) were used as bio-fertilizer to grow the wheat plant. Both the Number of leaves and the average size of the leaves of the plants were higher for both the MWGMB compared to conventional NPK fertilizer. Acknowledgements This work was supported by Qatar Science and Scopus

A pot experiment was conducted in the net house of the Department of Agricultural Chemistry, Bangladesh Agricultural University, Mymensingh during the period from October, 2012 to April, 2013 to compare the phosphorus use efficiency (PUE) as well as the effect of phosphorus (P) on yield and quality of six varieties of lentil and grass pea (three from each crop). The experiment was laid out in a Completely Randomized Design (CRD) with two treatments and three replications. Treatments included optimum phosphorus (P) dose i.e. @ 25 kg P ha-1 (P1) and control (P0). Among the observed parameters, application of P fertilizer had performed better over control (P0) in all varieties of lentil and grass pea. Among the three varieties of lentil (viz. BARI masur-5, BARI masur-6 and BARI masur-7), the best yield performance was observed in BARI masur-5. Similarly, among the three varieties of grass pea, (viz. BINA khesari-1, BARI khesari-1 and BARI khesari-2), BINA khesari-1 showed the best yield performance. In lentil varieties, BARI Masur-5 produced the highest seed yield (2.78 g pot-1), whereas, BINA kheshari-1 gave the highest yield (3.38 g pot-1) among grass pea varieties. In case of lentil and grass pea varieties, highest seed P contents were observed in BARI masur-5 (1.36%) and BINA khesari-1 (1.22%) varieties, respectively. Maximum PUE (192.5%) for lentil varieties was found in BARI masur-5 and that of (234.0%) for grass pea varieties was in BINA khesari-1. On the other hand, P used per unit seed yield in lentil and grass pea was highest in BARI masur-5 and BINA khesari-1, respectively. Therefore, our farmer can be benefitted by cultivating BARI masur-5 and BINA khesari-1 through maximized yield using less amount of P fertilizers.Res. Agric., Livest. Fish.2(2): 271-277, August 2015

The power generated by a Vertical Axis Wind Turbine (VAWT) depends on the drag force generated by the individual blades and interactions between them in a rotating configuration. The present Analysis is on attempt to predict numerically the coefficient of drag and other aerodynamic parameters for a four blade Vane type Vertical Axis Wind Turbine (VVAWT) with different blades and vanes position. For numerical investigation, commercial available computational fluid dynamics CFD software GAMBIT and FLUENT are used. In this numerical analysis the Shear Stress Transport (SST) k-ω turbulence model is used which is better than the other turbulence models available as suggested by some researchers. The computed results show good agreement with published experimental results.

In this paper, thermal analysis of cup shaped article using finite element method for flash-less cold forging is presented. The work-piece specifications are calculated by developing mathematical relations between volumes of die cavity and work-piece. The three dimensional FE simulation is made by DEFORM F3 V 6.0 and geometrical modeling for the die and the work-piece is performed by SOLIDWORKS 2007 4.0. The work-piece used is of AISI 1045 steel and the die material is steel (AISI D2). The results of numerical simulation and analytical calculations are found in satisfactory agreement with the experimental results.

Wind energy has seen a rapid growth worldwide. Wind turbines are typical devices that convert the kinetic energy of wind into electricity. Researches in the past have proved that Vertical Axis Wind Turbines (VAWTs) are more suitable for urban areas than Horizontal Axis Wind Turbines (HAWTs). In the present design of the VAWT, the power prodused depends on the drag force generated by the individual blades and interactions between them in a rotating configuration. Numerical simulation for the aerodynamics of VAWT with tow different rotors (Three and Foure blades ) having movable vanes are curred out. The For numerical simulation, commercially available computational fluid dynamic (CFD) softwares GAMBIT and FLUENT are used. In this work the Shear Stress Transport (SST) k-ω turbulence model was used which is better than the other turbulence models available as suggested by some researchers. The predicted results show agreement with those reported in the literature for VAWT having different blades designs.

Alternatively layered composite sheets of commercially pure (99.8 pct purity) aluminum and an Al-0.3wtpctSc alloy (either in the supersaturated solid solution or age-hardened conditions) were generated through accumulative roll bonding for up to 5 cycles. The transverse sections of the sheets were examined to investigate the microstructure and texture inhomogeneities developed during the rolling process. Electron backscatter diffraction and transmission electron microscopy was used for this investigation. It was found that an inhomogeneous microstructure and texture was developed through the aluminum layers of the sheet thickness. The nature of inhomogeneities changes as the ARB bonding progresses to higher cycles. Microstructural inhomogeneities remain prominent in the first ARB cycle and diminish during the subsequent cycles. Texture inhomogeneities appear in different forms as rolling progresses. High frictional shear forces in the surface and in-plane shear forces across bonding interfaces derive these inhomogeneities.

Fracture of silicon wafers is responsible for lower than desirable manufacturing yields in the photovoltaic industry. This study investigates the fracture response of polycrystalline silicon wafers under sliding contacts at different length scales, by means of macro and microscratch tests which simulate cutting processes. The dominant fracture modes were found to be partial cone cracking (macro) and radial cracking (micro). Statistical analysis of the critical loads for crack initiation showed that polycrystalline wafers are weaker than their single-crystal counterparts, that is, they crack at lower applied loads under comparable conditions. Moreover, the Weibull modulus of polycrystalline silicon was found to be the average of the relevant single-crystal directions. Subsequent microscopic observations and flexure tests reveal that the lower resistance of polycrystalline silicon to scratch fracture is due mainly to the presence of relatively large polishing defects, and not to the weakness of its grain boundaries. Alternatives are proposed to minimize damage during ingot cutting, with a view to minimizing wafer breakages during wafer handling and machining.

The purpose of this study was to use statistical design of experiments to develop a stable aqueous enteric coating formulation containing stabilizing excipients, such as polyethylene glycol that can minimize hydroxypropyl methylcellulose acetate succinate aggregation and minimize spray-nozzle clogging at elevated processing temperatures. The mechanisms of stabilization (i.e. charge stabilization and molecular interactions) were studied by performing zeta potential and FTIR studies. Electrostatic stabilization by sodium lauryl sulfate and hydrogen bonding by polyethylene glycol provided dispersion stability and yielded a stable aqueous coating formulation that prevented spray-nozzle clogging. An enteric coated tablet with better gastric resistance was obtained by incorporating fumed silica (Aerosil® R972) as the anti-tacking agent instead of talc. Dissolution testing on the riboflavin enteric coated tablets showed a good enteric release profile without releasing riboflavin in 0.1 N HCl, and completely disintegrating within 10 min in phosphate buffer (pH 6.8).

Layered composite structures can be generated in metallic sheets by roll bonding of dissimilar metals/alloys. In this investigation, heat treatable (Al(Cu)) and non-heat treatable (Al(Si)) aluminium alloys are roll bonded in sheet form. Large hardness differences between layers poses significant bonding challenges in the form of multiple necking within the hard Al(Cu) layers. For successful processing, it is vital to choose the candidate materials in a state of marginal hardness differences during rolling, but being capable of altering properties through subsequent heat treatments. Atomic diffusion takes place during heat treatment of the composite sheet and results in gradual hardness variation across sheet thickness. The Al(Cu) layers contribute to strength, whereas the Al(Si) layers provide protection from corrosion/wear-related degradation in the newly developed hybrid sheet. The overall mechanical properties of the heat-treated composite fall between the base alloys. The bonding interfaces are noted ...

The last years have proved that Vertical Axis Wind Turbines (VAWTs) are more suitable for urban areas than Horizontal Axis Wind Turbines (HAWTs). To date, very little has been published in this area to assess good performance and lifetime of VAWTs either in open or urban areas. The main goal of this current research is to investigate numerically the aerodynamic performance of a newly designed cavity type vertical axis wind turbine having four blades. In the current new design the power generated depends on the drag force generated by the individual blades and interactions between them in a rotating configuration. For numerical investigation, commercially available computational fluid dynamic CFD software GAMBIT and FLUENT were used. In this numerical analysis the Shear Stress Transport (SST) k-ω turbulence model is used which is better than the other turbulence models available as suggested by some researchers. The computed results show good agreement with published experimental results.

SUMMARY Thermal modeling of temperature rise in high-power Li-ion battery cells and modules is presented here. Simulation results are validated by experiments. Results indicate that entropy heat generation plays a significant role in heat generation of Li-ion battery cells and should be included in simulation as a function of state of charge (SOC). Simulation results utilizing measured overpotential resistance and entropy heat generation provide the best fit when compared to experimental results. Resistance data provided by supplier shows significant difference compared with measured data and should be critically examined for any module design purposes. Copyright © 2013 John Wiley & Sons, Ltd.

Body centred cubic (BCC) β-phase multifunctional titanium alloys have been developed with a very unique combination of thermal and mechanical properties. In this investigation, a very low porosity Ti–36.8–Nb–2.7Zr–2.0Ta–0.44O (wt%) alloy was produced by powder sintering, hot forging, solution treatment and cold swaging. X-ray diffraction and transmission electron microscopy (TEM) of the solution treated alloy revealed the presence of a small amount of ω-phase in a predominantly BCC β-phase matrix. Electron backscatter diffraction (EBSD) of the swaged alloy revealed a highly elongated and fragmented microstructure, and a strong 〈110〉 fibre texture. TEM also revealed the existence of stress-induced twin lamella, dislocations and ω-phase. Consistent with previous studies on these types of alloys, the swaged alloy exhibited non-linear elasticity during tensile straining, low elastic modulus (45.4 GPa), high elastic limit (2.3%), high elongation to failure (8.1%), and a high yield strength (880 MPa) and tensile strength (940 MPa). The coefficient of thermal expansion was also low (∼5×10−6 K−1 between 50 and 300 °C) in this alloy.

In the study of microband formation during plastic deformation of face centered cubic metals and alloys, two theories have been proposed regarding the orientations of their boundaries: (i) they are aligned parallel to crystallographic planes associated with dislocation glide (i.e. {111} planes in FCC metals), or (ii) they are aligned in accordance with the macroscopic stress state generated during deformation. In this study, high resolution 3D electron backscatter diffraction (3D EBSD) was used to investigate the morphology and crystallographic nature of microband boundaries within a 19 × 9 × 8.6 μm volume of a deformed grain in commercial purity aluminum cold rolled to 22% reduction. It was found that microband boundaries correspond to both theories of orientation. Additionally, a single surface may contain both crystallographic and non-crystallographic alignments. Misorientations across boundaries in the regions of microband triple junctions have been identified for both boundary alignments.

A Hot-Lab is the major source of radiation exposure by medical technicians in a nuclear medicine set up. A table top bench shield is used to reduce this exposure which consists of a lead base and a lead wall in the bottom part while a viewing window is provided in the top part through the use of thick glass or leaded glass. In our laboratory, a home-made shield was used earlier which incorporated a 254mm ordinary glass window in the top and a thick lead wall at the bottom part. Recently a commercial bench shield was procured that uses a lighter lead glass window for better viewing. This lead glass gives an equivalent lead thickness of 2.2 mm. The present work was taken up to study the changes in the radiation exposure to nuclear medicine technicians due to this change in the bench shield. The effective doses received by two technicians were 0.937 mSv and 1.098 mSv respectively when they worked for two months using the old table top bench shield. This dose came down substantially to 0.292 mSv and 0.187 mSv respectively, when they used the new table top bench shield for the same period of time. Side by side, the radiation reaching the outer surfaces of the glass shield and the lead wall were measured due to a radiation source placed at 0mm, 10mm and 20mm from the respective inner surfaces. For the lead shield the dose rates were not much different between the two models, but for the glass window, the commercial one gave much reduced dose rate. Although the dosage was higher in the indigenously made device, the duty schedules of the technicians were rotated so that none received dosage greater than safe limits over a full year. DOI: http://dx.doi.org/10.3329/bjmp.v5i1.14669 Bangladesh Journal of Medical Physics Vol.5 No.1 2012 37-40