Metallurgical and Materials Transactions A - Banding in commercial dual-phase steels, such as banded ferrite and pearlite or ferrite and martensite microstructures, is inherited from segregation... 相似文献
The field of information systems (IS) remains ill-defined, facing problems of recognition and identity crisis. Several papers and debates have been dedicated on this topic for over three decades. The focus of these debates have largely centered on the state of the IS field in Americas and Europe and with a limited study conducted in the Asia–Pacific context. This study attempts to assess the field in the Indian context and highlight the challenges and issues faced by IS faculties in India. Based on literature survey of the seminal papers in the field, we identified the salient topics of interest to IS researchers: identity of the IS field; diversity of the field; research approaches, methods and rigor; reference disciplines; journals and conferences; and IS course and curriculum. A two-phase study was carried out to explore the interest generated by the IS field in India. In the first phase, secondary data review of leading business schools in India was carried out to understand their focus on IS as an academic discipline. In the second phase, we conducted interviews of IS researchers from the premium business schools in India. In our study, we analyze the research focus of IS faculties in B-schools in India, analyze the composition of the faculty pool and the nature of research work undertaken by them. Our study points at the restricted focus of IS researchers in India around a few narrow areas, with a significant breadth of topics not being explored for research. We found the identity struggle of the field to be prominent, which was further compounded by the limited number of active, IS researchers. The growing importance of qualitative techniques in IS research, the challenges of developing a sound base in multiple reference disciplines and the need for making IS course interesting for business school students were some of the other significant observations. Our study also highlighted the paradox of the success of the IT industry in India leading to reduced enrollment of IS courses in B-Schools. We conclude by providing recommendations to B-school deans and directors. 相似文献
One of the most challenging problems encountered in developing RF circuits is accurate prediction of MOS behavior at microwave signal and data frequencies. An attempt is made in this work to accurately model the device input impedance for the 1-20-GHz frequency range. The effect of device length and single-leg width on the input impedance is studied with the aid of extensive measured data obtained from devices built in 0.11-/spl mu/m and 0.18-/spl mu/m technologies. The measured data illustrates that the device input impedance has a nonlinear frequency dependency. It is also shown that this variation in input impedance is a result of gate poly-silicon depletion, which can be modeled by an external RC network connected at the gate of the device. Excellent agreement between the simulation results and the measured data validates the model in the device active region. 相似文献
Spatial database operations are typically performed in two steps. In the filtering step, indexes and the minimum bounding rectangles (MBRs) of the objects are used to quickly determine a set of candidate objects. In the refinement step, the actual geometries of the objects are retrieved and compared to the query geometry or each other. Because of the complexity of the computational geometry algorithms involved, the CPU cost of the refinement step is usually the dominant cost of the operation for complex geometries such as polygons. Although many run-time and pre-processing-based heuristics have been proposed to alleviate this problem, the CPU cost still remains the bottleneck. In this paper, we propose a novel approach to address this problem using the efficient rendering and searching capabilities of modern graphics hardware. This approach does not require expensive pre-processing of the data or changes to existing storage and index structures, and is applicable to both intersection and distance predicates. We evaluate this approach by comparing the performance with leading software solutions. The results show that by combining hardware and software methods, the overall computational cost can be reduced substantially for both spatial selections and joins. We integrated this hardware/software co-processing technique into a popular database to evaluate its performance in the presence of indexes, pre-processing and other proprietary optimizations. Extensive experimentation with real-world data sets show that the hardware-accelerated technique not only outperforms the run-time software solutions but also performs as well if not better than pre-processing-assisted techniques. 相似文献
Chalcopyrite thin films of CuIn0.75Al0.25Se2 have been grown by a two-stage process containing e-beam evaporation of a threefold (In/Cu/Al/Se) precursor deposition onto glass substrates in a high vacuum followed by post selenization at various temperatures (300–550 °C) using a horizontal tubular furnace. The X-ray diffraction pattern of precursor layers selenized at?≤?525 °C shows the formation of co-existence of CuInSe2 and Cu(In,Al)Se2 phases, as well as a mixture of two Cu(In,Al)Se2 phases with different Al content. The precursor layers selenized at 550 °C results in the formation of single-phase Cu(In,Al)Se2 thin films. The presence of an intense A1 mode at 174.7 cm?1 in the Raman spectra of selenized films at 550 °C confirms the growth of Cu(In,Al)Se2 phase. The energy-dispersive spectra of stacked layers selenized at 550 °C shows a Cu-poor and (In?+?Al)-rich composition with atomic ratios of Cu/(In?+?Al)?=?0.79, Al/(In?+?Al)?=?0.25, and Se/(Cu?+?In?+?Al)?=?0.98. The secondary ion mass spectra depth study reveals a shift in Al distribution from graded to uniform with an increase in selenization temperature to 550 °C. The stacked layers selenized at 550 °C reveal a uniform distribution of void-free dense grains (~?0.7 μm). Optical and electrical studies of selenized Cu(In,Al)Se2 films at 550 °C show a direct band gap of 1.22 eV with a higher hole mobility of 14.0 cm2/V-s. The heterojunction solar cell of p-Cu(In,Al)Se2/n-CuAlSe2 was numerically simulated using SCAPS-1D software, yielding a high power conversion efficiency (η) of 21.01%.
This paper reports on the photoluminescence properties of Na1−yLiyCa1−xPO4:xEu2+ phosphors synthesized by a solid state reaction method. The prepared phosphors have been thoroughly characterized by means of X-ray diffraction (XRD), Field-emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectrum (FTIR), Raman spectrum, Thermo gravimetric and differential thermal analysis (TG–DTA) and photoluminescent spectral measurements. The structure of Na1−yLiyCa1−xPO4:xEu2+ phosphors were found to be orthorhombic in nature with a sphere-like morphology and having the particle size in micrometer range. The excitation spectra of NaCaPO4:Eu2+ phosphors revealed a broad excitation band having its maximum intensity at 373 nm and ranging from 250 m to 450 nm. Incidentally, it matches well with the ultraviolet (UV) radiation of light-emitting diodes (LEDs). Upon 373 nm excitation, these phosphors exhibited intense bluish-green emission band centered at 505 nm. The effect of sintering atmospheres and co-doping of lithium ions on the photoluminescence properties of the NaCaPO4:Eu2+ phosphors were studied and explained suitably. The obtained results indicate that the prepared NaCaPO4:Eu2+ phosphors are promising bluish-green candidates for the phosphor-converted white LED applications. 相似文献
As online spatial datasets grow both in number and sophistication, it becomes increasingly difficult for users to decide whether
a dataset is suitable for their tasks, especially when they do not have prior knowledge of the dataset. In this paper, we
propose browsing as an effective and efficient way to explore the content of a spatial dataset. Browsing allows users to view the size of
a result set before evaluating the query at the database, thereby avoiding zero-hit/mega-hit queries and saving time and resources.
Although the underlying technique supporting browsing is similar to range query aggregation and selectivity estimation, spatial
dataset browsing poses some unique challenges. In this paper, we identify a set of spatial relations that need to be supported
in browsing applications, namely, the contains, contained and the overlap relations. We prove a lower bound on the storage required to answer queries about the contains relation accurately at a given resolution. We then present three storage-efficient approximation algorithms which we believe
to be the first to estimate query results about these spatial relations. We evaluate these algorithms with both synthetic
and real world datasets and show that they provide highly accurate estimates for datasets with various characteristics.
Recommended by: Sunil Prabhakar
Work supported by NSF grants IIS 02-23022 and CNF 04-23336. An earlier version of this paper appeared in the 17th International
Conference on Data Engineering (ICDE 2001). 相似文献