Effect of laser irradiation on abrasive wear of glass fibre polyester composite

Low power laser irradiation improves the wear resistance of glass-fibre-reinforced polyester composites, if irradiation time is restricted to short periods. Laser irradiation (i) enhances crosslinking in unsaturated polyester, (ii) modifies surface microstructure and (iii) increases the hardness of the composite material. Improved mechanical properties, in turn, increase the material's resistance to wear.     

Investigations on weld joining of sisal CSM‐thermoplastic composites

An experimental study was conducted to investigate joint efficiency of both, butt, and lap joints of sisal CSM reinforced polymer composites. The thermoplastics, HDPE, and polypropylene (PP) were used separately as matrices in composites. Sisal‐HDPE composites exhibited excellent improvement in tensile strength that reached up to 47.5 MPa at 30 phr loading of sisal CSM as compared with 17.7 MPa of HDPE. Significant improvement in HDT was also observed that increased from 60.2 to 75°C on 0 to 30 phr reinforcement of sisal CSM in HDPE. Similar improvement was noticed with PP where in HDT improved from 69 to 87.6°C on incorporation of 0 to 30 phr sisal CSM. Hot tool welding process was employed for joining the composite materials. The joint efficiency of butt joint of HDPE was observed as 30%. It varied from 48 to 59% for lap joints of different sizes. The joint efficiencies of 20 mm lap joints of different compositions were observed as 59, 98, 75, and 58% in 0, 10, 20, and 30 phr Sisal CSM‐HDPE composites, respectively. Welded joint strengthening is attributed to partial reinforcement of interface that occurs during softening of matrix material which allowed spring back of originally pressed fibers followed by their repositioning in the welded part. POLYM. COMPOS., 36:214–220, 2015. © 2014 Society of Plastics Engineers     

Architecture as Conciliator: Toward a Unifying Principle in Architectural Education

We believe that architecture has lost its role as conciliator between humanity and the universe, it has lost much of its meaning. We use an example of a studio problem and process to explore issues in architecture, science, and meaning as they relate to architectural education. The confrontation of this problem in architectural education should involve the infusion of scientific thought and theoretical issues into the design studio, as well as other courses, to aid students in formulating their own world view in order to create an architecture of meaning. A seven-week design studio offered to second-year students included reading Stephen W. Hawking's A Brief History of Time and analyzing the spatial theories outlined in the book. This research informed site analysis as well as the architectural and landscape design.     

Influence of MA-g-PP on abrasive wear behaviour of chopped sisal fibre reinforced polypropylene composites

In this paper, chopped sisal fibre reinforced polypropylene composites with and without maleic anhydride grafted polypropylene (MA-g-PP) were developed. Different amounts of MA-g-PP, e.g. 1, 2 and 5-wt% were added to modify the composites. Abrasive wear and mechanical properties of sisal fibre reinforced polypropylene composites were determined. Addition of MA-g-PP improved the mechanical properties of the composite. Effects of MA-g-PP coupling agent, sliding distance and load on abrasive wear behaviour of sisal fibre reinforced PP composites were studied by using a SUGA abrasion tester. Addition of MA-g-PP coupling agent has significantly influenced the wear resistance of sisal fibre reinforced PP composites. It is observed in chopped sisal fibre reinforced polypropylene composite that initially at low loads (i.e. 1 N and 3 N), sample having 1-wt% MA-g-PP exhibited maximum wear resistance but at higher applied loads (i.e. 5 N and 7 N), sample having 2-wt% MA-g-PP offered maximum wear resistance. The higher concentration of MA-g-PP, i.e. 5-wt% has increased the internal slippage of chain molecules, leading to lowering the wear resistance of composite. Worn and fractured surfaces were analyzed and discussed using SEM.     

Thermal and rheological behavior of ultrafine fly ash filled LDPE composites

The specimens containing different volume fractions of ultrafine fly ash in LDPE were prepared with the help of two roll mixing mill and the hot‐plate compression‐molding machine. Thermal and rheological properties were evaluated using DSC and parallel‐plate rotational‐rheometer. The effect of composition variation on melt enthalpy, crystallinity, shear viscosity, shear stress and first normal stress difference was studied and reported here. The addition of ultrafine fly ash in LDPE decreased the melt enthalpy of the specimen. Slight decrease in the crystallinity of LDPE was observed on addition of fly ash. The shear stress as well as the shear viscosity both increased with the addition of ultrafine fly ash in LDPE. Two regions of shear thinning were observed at 200°C for fly ash filled LDPE. The first normal stress difference (N₁) reduced with fly ash content and with the increased temperature. The values of N₁ remained almost invariable at low shear region however a proportional increase was observed beyond the shear stress of 10 kPa. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

OPT++ : an object-oriented implementation for extensible database query optimization

In this paper we describe the design and implementation of OPT++, a tool for extensible database query optimization that uses an object-oriented design to simplify the task of implementing, extending, and modifying an optimizer. Building an optimizer using OPT++ makes it easy to extend the query algebra (to add new query algebra operators and physical implementation algorithms to the system), easy to change the search space, and also to change the search strategy. Furthermore, OPT++ comes equipped with a number of search strategies that are available for use by an optimizer-implementor. OPT++ considerably simplifies both, the task of implementing an optimizer for a new database system, and the task of evaluating alternative optimization techniques and strategies to decide what techniques are best suited for that database system. We present the results of a series of performance studies. These results validate our design and show that, in spite of its flexibility, OPT++ can be used to build efficient optimizers. Received October 1996 / Accepted January 1998     

Effects of Starting Powder Characteristics on Bulk Assembly of Titania

Seven nanoscale titanias synthesized from a sulfate process were investigated for rheological characterization. Alteration of synthesis parameters had resulted in variation of the powder surface area and soluble sulfate level from powder to powder. The powder differences were further corroborated in stress-controlled rheometry where the viscoelastic yield stress of a suspension was seen to vary strongly with processing history. Capillary and torque rheometry further showed the dependence of processing history on steady-state extrusion pressure and steady-state mixing torque. The powders were washed to determine whether sulfate equilibration through washing could be used to circumvent the synthesis parameter differences.     

Development of celsian ceramics from fly ash useful for X-ray radiation-shielding application

For the first time the capability of fly ash to produce barium containing radiopaque materials has been demonstrated. Fly ash which is a waste generated in power plants due to combustion of pulverized coal, has been utilized^a for making X-ray radiation-shielding materials. A novel method for making radiation-shielding materials utilizing fly ash and barium compound has been developed by ceramic processing route using phosphate bonding. The fly ash based radiopaque materials (FARM), i.e. shielding materials are characterized for their X-ray attenuation characteristics. The shielding, i.e. half value thickness (HVT) for different energies of X-ray photons for FARM have been computed and compared with conventionally used shielding materials, namely concrete and lead, it is found that the HVT of the fly ash based shielding materials, in comparison to concrete, is significantly very less for the various energies of X-ray photons.The X-ray powder diffraction studies confirmed the presence of monoclinic and hexagonal celsian and sanbornite as the major shielding phases and potassium aluminosilicate, sodium aluminosilicate and silicophosphate as the binder phases in the FARM and are responsible for providing bonding to the ceramic matrix leading to the effective shielding and mechanical properties. Scanning electron microphotographs have revealed the compacted plate like particles with hexagonal morphological characteristics of the various barium silicate and barium aluminosilicate (BAS) shielding phases in the matrix of radiopaque materials. The mechanical properties, namely compressive strength and impact strength evaluation test showed that FARM meets the standard specifications laid down for radiation-shielding concrete and ceramic tiles. Based on the above studies, it is found that FARM, can preferably be used for the construction of X-ray diagnostic and CT-scanner room to provide adequate shielding against X-ray photons.     

Classifying EEG and ECoG signals without subject training for fast BCI implementation: comparison of nonparalyzed and completely paralyzed subjects.

We summarize results from a series of related studies that aim to develop a motor-imagery-based brain-computer interface using a single recording session of electroencephalogram (EEG) or electrocorticogram (ECoG) signals for each subject. We apply the same experimental and analytical methods to 11 nonparalysed subjects (eight EEG, three ECoG), and to five paralyzed subjects (four EEG, one ECoG) who had been unable to communicate for some time. While it was relatively easy to obtain classifiable signals quickly from most of the nonparalyzed subjects, it proved impossible to classify the signals obtained from the paralyzed patients by the same methods. This highlights the fact that though certain BCI paradigms may work well with healthy subjects, this does not necessarily indicate success with the target user group. We outline possible reasons for this failure to transfer.     

Effects of hybrid composition of LCP and glass fibres on abrasive wear of reinforced LLDPE

The hybrid of liquid crystalline polymer (LCP) fibres and glass fibres (GF) provide a combination of modulus and toughness to semi-crystalline linear-low-density-polyethylene (LLDPE). LCP and GF fibres reinforced composites were studied using two-body abrasion tester under different applied loads. Two sets of fibre reinforced LLDPE, 10 and 20 vol%, were investigated. The contents of LCP and glass fibres were varied as 25, 50, 75 and 100 vol% of overall volume of fibres in LLDPE. The effect of replacing glass fibre with LCP fibre on wear is reported. Wear loss increased with the applied loads and glass fibre contents in LLDPE. The replacements of glass fibres with LCP fibres improved abrasive wear resistance of composite. The composite containing 20 vol% of glass fibres in LLDPE showed the specific wear rate nearly double to that of LCP fibre reinforced LLDPE. Incorporation of LCP fibre improved wear resistance of glass fibre reinforced LLDPE. Worn surfaces were studied using SEM. Glass fibres were broken in small debris and removed easily whereas LCP fibres yielded to fibrillation during abrasive action. The overall wear rate was governed by the composition and test conditions.