1,048 research outputs found
Externally-oriented Small and Medium Enterprises: Predicament and Possibilities
Get PDFThis paper addresses emerging issues concerning externally-oriented SMEs in India and the nature of important business risks faced by them during the period of global financial crisis. The unimpressive export performance of SMEs during the period of reforms is also a reflection of the limitations of the institutional support as also weak forms of production organization. The state needs to play a proactive role in contributing to enhancing SME competitiveness. Whereas financially well protected Indian SMEs are likely to be more competitive and efficient, a greater recognition of the potential of domestic market and provision of business-facilitating infrastructure holds the key for success of SMEs across board.Financial Crisis, SMEs, Exports, Business Risks
Crystal and mesophase structure of a bicyclohexyl cyano mesogen
No full text: The phase behaviour of 4-[trans-4-(trans-4-propylcyclohexyl)cyclohexyl]benzonitrile, C22H31N, 1, has been examined. This compound has two different solid phases, denoted I and II, and exhibits thermotropic liquid-crystalline behaviour, with a remarkable interval of stability of the mesophase between the lower melting solid phase (75 °C) and the isotropization temperature (247 °C). The crystal and molecular structures of solid phase I have been determined at 173 K. The cyclohexyl rings both adopt the chair conformation and are equatorially substituted. The packing of 1 in the crystalline state is driven by the antiparallel arrangement of cyano dipoles with the formation of close contacts involving the strong cyano acceptor and weak aromatic C-H or aliphatic C-H donors. The crystal packing is discussed and compared with X-ray diffraction data in the liquid-crystalline state. The combination of thermal analysis, optical polarizing microscopy and X-ray diffraction analysis suggests that the mesophase is a partially ordered smectic phase. The lamellar structure of the mesophase is retained in crystalline solid phase II obtained by cooling the liquid-crystalline phase
A new tool for ancient artefact conservation studies: electron diffraction tomography to study blue corrosion product in Chinese bronze sample
No full textNanotubes tethered laccase biosensor for sensing of chlorophenol substances
No full textIncreasing population density and technological developments resulted in an increase of chlorophenols (CPs) that have been identified as emerging contaminants. CPs can take several routes into the environment, such as industrial waste, pesticides, insecticides, and degradation of complex chlorinated hydrocarbons. CPs have a potential hazard to environmental sources and cause long-term exposure for animals and humans. Determination of CPs in the environment is difficult because of low analyte concentrations and complex matrixes. Thus, developing effective approaches is necessary. Laccases, which are multicopper oxidases capable of oxidizing substituted phenols and benzenediol derivatives, without any cofactor, are used in biosensors due to their biocatalytic properties, eco-friendliness, and efficiency. Carbon nanotubes (CNTs) show excellent electrical conductivity, mechanical strength, and biocompatibility. They are suitable for enzyme immobilization, which can improve stability and catalytic efficiency. This chapter provides a general approach to CNTs based laccase biosensors to detect CPs for environmental, industrial, and pharmaceutical analysis
Towards Energy Efficient And Reliable 3D Manycore Chip Enabled By Machine Learning
Get PDFThesis (Ph.D.), Electrical Engineering, Washington State UniversityAs the demand for high performance and energy efficient computation has increased significantly, manycore chip architectures have emerged as a mainstream solution paradigm. A three-dimensional Network-on-Chip (3D NoC) that takes the advantages of amalgamation of two revolutionary technologies namely the NoC and 3D integration, improves the performance of manycore chip significantly. Existing 3D NoC architectures predominantly follow straightforward extension of regular 2D NoCs and suffer from multi-hop communications. In this context, we propose the design of 3D small-world NoC (3D SWNoC) architecture to overcome the challenges of mesh-based architectures and improve the performance of the chip.
In addition, the performance of 3D SWNoC mainly depends on the placement of cores and links. This is an instance of combinatorial optimization problem, which is computationally intractable and needs intelligent exploration of design space to reach physically plausible and near-optimal designs. We adapt a machine learning-based approach to overcome these computational challenges and design an efficient and robust NoC architecture while ensuring significant reduction in convergence time.
The anticipated performance gain of 3D NoCs degrades in the presence of TSV failures due to fabrication limitations and workload induced stress. We analyze the reliability concerns associated with 3D ICs. We propose several mitigation techniques to counteract TSV failures, which includes VFI-based power management methodology, spare TSV allocation technique, and adaptive routing strategy. We carry out extensive experiments to characterize their performance to improve both reliability and lifetime of 3D NoCs.
Recently, monolithic 3D (M3D) integration has been proposed as an alternative to TSV-based 3D integration for designing ultra-low-power and high-performance circuits and systems. The smaller dimensions of monolithic inter-tier vias (MIVs) offer high density integration, flexibility of partitioning logic blocks across multiple tiers resulting in significant reduction of the total wire-length. In this work, we explore the design space of M3D-enabled small-world NoC architectures and present a comparative performance evaluation with TSV-based counterparts.
Finally, we summarize our contributions and outline some promising directions for future work based on the findings of this work. Future work includes incorporating machine learning approaches for on-chip security analysis and development of online mitigation techniques against external attacks.Washington State University, Electrical Engineerin
Multi-objective optimization of mechanical properties of chemically treated bio-based composites using response surface methodology
Get PDFEco-friendly surface treatment of natural fibers using sodium acetate (CH3COONa) affects the mechanical properties of the developed composites in many ways. In present study, geometrically different kenaf fiber mats (bidirectional (BC), unidirectional (UD) and randomly oriented (RO) were treated at different concentration (10, 15 and 20 percentage w/w) of sodium acetate aqueous solution for varying time (24, 48 and 72 hr.) at room temperature. PLA (Poly-Lactic Acid) was used for the fabrication of treated fiber reinforced bio-degradable composites. The influence of above parameters on mechanical properties were studied. Response surface methodology (RSM) module face centered central composite design was employed for the development of regression models. The relationship between chemical treatment parameters and mechanical responses were predicted by quadratic model. In this study, predicted model was developed for two numerical factors (chemical concentration (CC) and treatment time (TT)) and one categorical factor (type of mat (TOM)). Tensile strength (TS), flexural strength (FS) and impact strength (IS) are considered as response variables. The statistical analysis showed that chemical concentration, treatment time and kenaf mat type have individually and interactively influenced the response of experiments. Chemical concentration was found to be the most influencing factor among all for the changes in mechanical properties. Optimization of input variables was done based on predicted model within bounded reason of responses
α-"NaLuF₄": a structure with sixfold twinning, modulation and diffuse scattering : structure determination and disorder modelling
Get PDFHexagonal NaLnF4 compounds are a family of light up-conversion materials which emit visible light upon IR excitation e.g. NaLnF4 shows green and blue emission for Er3+, Yb3+ and Tm3+, Yb3+ doping, respectively. Understanding of the properties of these technologically important materials requires knowledge of their structure at an atomic level. The theme of this doctoral thesis is the modelling of disorder in the single crystal structure of -NaLuF4 obtained from the melt with a likely composition of Na5Lu9F32. Two different phases of NaLuF4 have been identified and all studied in this doctoral thesis. The motivation of this study is to reveal the complex structure within the crystals and to make a systematic investigation of the complex disorder by exploiting the available methods and consequently to understand the driving force for the formation and stability of the material. Phase I shows strong Bragg scattering, commensurate satellite reflections and significant diffuse scattering. The strong main reflections in the apparently “cubic” reciprocal lattice rows are not collinear and split at high diffraction angles. This suggests the crystal is a multiple twin of lower symmetry with near overlap of reflections. If the satellite reflections are treated as Bragg peaks then a fivefold orthorhombic supercell and six fold twinning follow with a likely space group of C mmm. Phase II of the sample which comes from another part of the same ampoule crystalized from the melt shows strong Bragg scattering and significant diffuse scattering but no satellite reflections. The nature of the diffuse scattering is different in the two phases. In Phase II, the main reflections with apparent “cubic” symmetry have a similar nature to those of Phase I and the structure can also be described as a sixfold orthorhombic twin. The main reflections vary in size and position from low diffraction angle to high angle. To account for this variation an increased mask size was used to integrate the main reflections. To avoid problems arising from the different peak profiles of main and satellite reflections, the latter were integrated with a non-crystallographic absence condition that eliminates the main reflections during the data integration procedure. These non-trivial data integration procedures play a key role for optimal intensity i extraction, which is essential for being able to correctly model and refine the structure. The first step of the structure determination was to establish the average structural model based on the main reflections and ignoring the supercell. The initial model was derived from the structure of CaF2. Considering only the positions of the heavy atoms in the asymmetric unit of the small unit cell, the average structure may be described about equally well in two different ways for both the phases. The two possible descriptions of the structure can be understood from the eigensymmetries of the heavy metal atom positions. The presence of residual electron density in the difference Fourier map of both models was interpreted in terms of disordered fluorine atoms. Their positions are chemically more meaningful for one of the two heavy atom models. For the Phase I structure, the phases of the superstructure reflections were determined by band flipping implemented in the program SUPERFLIP. The reconstructed difference electron densities shows two distinct commensurately modulated parallel columns of cations: one with varying Na+/Lu3+ occupancy and one with additional positional displacement of the ions from the average structure positions. Interestingly, two different solutions result from band flipping of superstructure reflections with equal probability. These two solutions differ only in the details of the positional and occupational modulation. As the main and satellite reflections could not be refined simultaneously due to the twinning, the refinement was performed only using the superstructure reflections. Although the two distinct solutions refine well, bond valence calculations suggest one solution to be chemically more meaningful than the other. Refinement based solely on the superstructure reflections and the information from difference electron density maps were successfully tested for the first time. The diffuse scattering in the structures may be a result of the strain in the twin boundaries and possible further occupational and positional disorder which may correlate with the up-conversion properties of the crystal. However, the sixfold twinning, the presence of which had not been anticipated initially, severely complicates the quantitative interpretation of the diffuse scattering. Consequently, a further analysis of the diffuse scattering has not been undertaken in this work. In this study it was shown that non-trivial data integration methods and use of non-crystallographic absence conditions play a crucial role for optimal intensity ii extraction in case of rare sixfold pseudomerohedral twinning. It was also shown in this study that bond valence calculations are important when structural refinement does not converge to a unique solution
Investigations on Multilevel Six-Phase Motor Drives With Nonsinusoidal Back EMF for Fault-Tolerant Transportation Applications
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