Novel flow apparatus for investigating shear-enhanced crystallization and structure development in semicrystalline polymers

An instrument to study the effects of shearing on the crystallization process in semicrystalline polymers is described. It can impose transient stresses similar to those encountered in polymer processing and provides in situ monitoring of microstructure development during and after cessation of flow. Box-like wall shear stress profiles (rise and fall times under 50 ms with maximum wall shear stress on the order of 0.1 MPa) can be applied for controlled durations. A unique feature of our device is that it accommodates a wide variety of real-time probes of structure such as visible and infrared polarimetry and light and x-ray scattering measurements. The design also allows us to retrieve the sample for ex situ optical and electron microscopy. Data are acquired with millisecond resolution enabling us to record the extent of shear deformation of the polymer melt during the pressure pulse. Our device works with small sample quantities (as little as 5 g; each experiment takes ~ 500 mg) as opposed to the kilogram quantities required by previous instruments capable of imposing comparable deformations. This orders-of-magnitude reduction in the sample size allows us to study model polymers and new developmental resins, both of which are typically available only in gram-scale quantities. The compact design of the shear cell makes it possible to transport it to synchrotron light sources for in situ x-ray scattering studies of the evolution of the crystalline structure. Thus, our device is a valuable new tool that can be used to evaluate the crystallization characteristics of resins with experimental compositions or molecular architectures when subjected to processing-like flow conditions. We demonstrate some of the features of this device by presenting selected results on isotactic polypropylenes

Bin packing algorithms for virtual machine placement in cloud computing: a review

Cloud computing has become more commercial and familiar. The Cloud data centers havhuge challenges to maintain QoS and keep the Cloud performance high. The placing of virtual machines among physical machines in Cloud is significant in optimizing Cloud performance. Bin packing based algorithms are most used concept to achieve virtual machine placement(VMP). This paper presents a rigorous survey and comparisons of the bin packing based VMP methods for the Cloud computing environment. Various methods are discussed and the VM placement factors in each methods are analyzed to understand the advantages and drawbacks of each method. The scope of future research and studies are also highlighted

Design of SPI(Serial Peripheral Interface) Protocol with DO-254 Compliance

The objective is to design the SPI protocol compliant with avionic hardware design standards (D0-254). This is to make sure that the protocol follows the most stringent standards so as to develop a fool proof design that would be highly reliable and would not fail under conventional circumstances. The significance of this project is designing the Serial Peripheral Interface (SPI) protocol in the DO-254 flow which is an industry standard used for the hardware process. Using DO-254 standards SPI is coded in Verilog. Single Master-Single Slave, Independent Slave configuration, Daisy Chain configuration all the three designs are designed following the rule sets of DO254. It is verified using the assertion based verification (ABV) or System Verilog Assertions (SVA)

Allylation of p-ketoaldehydes and functionalized imines by diallyltin dibromide: formation of skipped and conjugated dienes

Diallyltin dibromide reacts with β-keto-aldehydes possessing no aromatic side groups and with (hydroxy) aryl imines to afford the expected homoallyl alcohols or amines respectively. With β-ketoaldehydes having aromatic side groups, skipped or conjugated dienes are obtained depending on whether or not an aqueous work up procedure is used

Effect of Explosive Shapes (in Sand Buried Condition) on the Failure of a Circular Clamped Plate of Protective Vehicle

Protective vehicles like armoured personnel carriers (APCs) require assessment of failure of structural elements subjected to impulsive load resulting from explosive blast under sand buried conditions. The explosive shape and location of detonation affect the failure in near field region. In the present study, a circular clamped Rolled Homogenous Armour (RHA) steel plate has been modelled using JC strength & damage model and explosive using JWL equation. Initially, the reflected pressure and specific impulse for a fixed quantity of explosive (3.75 kg) of various shapes i.e. sphere, hemisphere, cylinders with Length to Diameter (L/D) ratio varying from 0.1 to 1 were studied for sand buried at a standoff distance of 118.1 mm. Further, studies were extended for cylindrical charges of φ 213.77 mm with conical 120°-150° and hemispherical cavities with radius of R1.2-R1.8. It was observed that, reflected pressure and specific impulse is much higher for hemispherical cavity of R1.2. The permanent deformation obtained using non-dimensional impulse is valid for explosives without cavities. However, the cavity charges produce failure of plate in the central region of the charge. The critical impulse emerges as an important parameter for assessing failure due to cavity charges. In addition, the scale down experiment is conducted to validate the effectiveness of cavity charges. It can be concluded that cavity charge with hemispherical radius of R1.2 can provide highest damage to RHA plates in close standoff distance

Shallow sea bottom farming: Multicrop system developed at Vizhinjam

Even though marilculture technology for various organisms like mussels, pearl oysters, lobsters and crabs has been developed during the last three decades by the CMFRI and several other institutions in India, there has been considerable practical difficulties for commercialising these programmes in Indian waters due to the rough weather conditions during the two monsoon periods as well as due to the nonavailability of adequate protected bays along the Indian coasts

Mechanical Behaviour and Fractured Surface Analysis of Bauxite Residue and Graphite Reinforced Aluminium Hybrid Composites

Composite materials application areas have gradually grown, allowing them to reach and conquer new markets from consumer products to specialized niche applications, advanced composite materials make up a significant portion of the engineered materials industry. The purpose of this study is to investigate the mechanical properties of Aluminum (Al), Red Mud particle (RMp), Graphite particle (GRp) hybrid composites. The different combinations of Rm and Gr wt. % were used to prepare Al-Rm-Gr and Al-Gr-Rm hybrid composites. The mechanical properties namely Ultimate tensile strength, Compressive strength and Hardness of prepared hybrid composites are tested to know the influence of reinforcements in Al-8011 alloy. Synthesis of Aluminum-Red Mud-Graphite hybrid composites done by Stir casting method. Drastic reduction in grain size (Grain refinement) was observed in Scanning Electron Microscopic images of fractured surfaces of the tensile specimens, with addition of RMp and GRp to the matrix alloy thus soft alloy is turned into hard and brittle material. Among all the compositions of hybrid composites series AG8R10 was observed to be higher compressive strength and hardness while AR8G10 has higher ultimate tensile strength