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| 2. |
- Gupta, A., et al.
(författare)
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Synthetic magnetic opals
- 2002
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Ingår i: Pramana (Bangalore). - : Springer Science and Business Media LLC. - 0304-4289 .- 0973-7111. ; 58:06-maj, s. 1051-1059
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Tidskriftsartikel (refereegranskat)abstract
- We present studies of novel nanocomposites of BiNi impregnated into the structure of opals as well as inverse opals. Atomic force microscopy and high resolution elemental analyses show a highly ordered structure and uniform distribution of the BiNi filler in the matrix. These BiNi-based nanocomposites are found to exhibit distinct ferromagnetic-like ordering with transition temperature of about 675 K. As far as we know there exists no report in literature on any BiNi compound which is magnetic.
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| 3. |
- Sharma, P., et al.
(författare)
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Ferromagnetism above room temperature in bulk and transparent thin films of Mn-doped ZnO
- 2003
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Ingår i: Nature Materials. - : Springer Science and Business Media LLC. - 1476-1122 .- 1476-4660. ; 2:10, s. 673-677
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Tidskriftsartikel (refereegranskat)abstract
- The search for ferromagnetism above room temperature in dilute magnetic semiconductors has been intense in recent years. We report the first observations of ferromagnetism above room temperature for dilute (<4 at.%) Mn-doped ZnO. The Mn is found to carry an average magnetic moment of 0.16 μ(B) per ion. Our ab initio calculations find a valance state of Mn2+ and that the magnetic moments are ordered ferromagnetically, consistent with the experimental findings. We have obtained room-temperature ferromagnetic ordering in bulk pellets, in transparent films 2-3 μm thick, and in the powder form of the same material. The unique feature of our sample preparation was the low-temperature processing. When standard high-temperature (T>700degreesC) methods were used, samples were found to exhibit clustering and were not ferromagnetic at room temperature. This capability to fabricate ferromagnetic Mn-doped ZnO semiconductors promises new spintronic devices as well as magneto-optic components.
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| 4. |
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| 5. |
- Abdelzaher, T., et al.
(författare)
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The aperiodic multiprocessor utilization bound for liquid tasks
- 2002
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Ingår i: 8th IEEE Real-Time and Embedded Technology and Applications Symposium, 2002. Proceedings. - 1545-3421. - 0769517390 ; , s. 173-184
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Konferensbidrag (refereegranskat)abstract
- Real-time scheduling theory has developed powerful tools for translating conditions on aggregate system utilization into per-task schedulability guarantees. The main breakthrough has been Liu and Layland's utilization bound for schedulability of periodic tasks. In 2001 this bound was generalized by Abdelzaher and Lu to the aperiodic task case. In this paper we further generalize the aperiodic bound to the case of multiprocessors, and present key new insights into schedulability, analysis of aperiodic tasks. We consider a special task model, called the liquid task model, representative of high-performance servers with aperiodic workloads, such as network routers, web servers, proxies, and real-time databases. For this model, we derive the optimal multiprocessor utilization bound, defined on a utilization-like metric we call "synthetic utilization". This bound allows developing constant-time admission control tests that provide utilization-based absolute delay, tees. We show that the real utilization of admitted tasks can be close to unity even when synthetic utilization is kept below the bound. Thus, our results lead to multiprocessor systems which combine constant-time admission control with high utilization while making no periodicity assumptions regarding the task arrival pattern.
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| 6. |
- Iqbal, Z., et al.
(författare)
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Evidence for a solid phase of dodecahedral C-20
- 2003
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Ingår i: European Physical Journal B. - : Springer Science and Business Media LLC. - 1434-6028 .- 1434-6036. ; 31:4, s. 509-515
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Tidskriftsartikel (refereegranskat)abstract
- Evidence is presented for the formation of a solid phase based on the smallest fullerene, C-20, in thin diamond-like carbon films deposited by ultraviolet laser ablation from diamond onto nickel substrates at room temperature in the presence of 10(-4) torr of cyclohexane or benzene. Laser desorption mass spectrometry from the films shows the presence of C-20, C-21 and C-22 species, while micro-Raman spectroscopy and electron diffraction from selected particles together with first principle density-functional calculations, indicate a cubic solid with dodecahedral C-20 Cages as building blocks. Unlike solid C-60 and fully protonated C-20, which are bound by van der Waals forces, the proposed structure is stabilized by linking of the C-20 dodecahedra with bridging carbon atoms at interstitial tetrahedral sites to form a face-centered-cubic lattice with 22 carbon atoms per unit cell.
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| 7. |
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| 8. |
- Morey, E. R., et al.
(författare)
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A simple method of incorporating income effects into logit and nested-logit models : Theory and application
- 2003
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Ingår i: American Journal of Agricultural Economics. - : Wiley. - 0002-9092 .- 1467-8276. ; 85:1, s. 248-253
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Tidskriftsartikel (refereegranskat)abstract
- Substantive income effects are incorporated in a logit or nested-logit model by assuming that utility is a piece-wise linear spline function of residual income. Specific income data are not required, only income by category. Expected compensating variation is easily and accurately approximated by the difference between expected maximum utility in the proposed and initial state, multiplied by the inverse of the individual's initial marginal utility of money. This approximation is almost exact because although any policy can, in theory, cause an individual to jump income categories, for most policies this probability will be very small.
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| 9. |
- Sharma, P., et al.
(författare)
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Analysis of ultraviolet photoconductivity in ZnO films prepared by unbalanced magnetron sputtering
- 2003
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 93:7, s. 3963-3970
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Tidskriftsartikel (refereegranskat)abstract
- Photoresponse characteristics of polycrystalline ZnO films prepared by the unbalanced magnetron sputtering technique have been analyzed for ultraviolet photodetector applications. Changes in the crystallographic orientation and the microstructure of the films due to in situ bombardment effects during film growth have been studied. Variations in photoresponse are correlated with the observed changes in the optical properties and the defect concentration in the films. ZnO films with (100) and (101) orientation possessing a small grain size exhibited a slow response with a rise time=1.99 s, whereas porous ZnO films with a mixed orientation (100), (002), and (101) and a larger grain size exhibited a fast response speed with a rise time=792 ms. The influence of trap levels on the slow and fast rising components of the photoresponse characteristics and the origin for a fast and a stable response have been identified. A slow rise in the photocurrent directly relates to the adsorption and desorption of oxygen on the film surface, and the fast rise is due to a bulk-related phenomena involving embedded oxygen. The magnitude of the photocurrent and the rise time are found to decrease considerably with increasing number of trap levels.
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| 10. |
- Sharma, P., et al.
(författare)
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Imaging of piezoelectric activity in laser-ablated c-axis-oriented LiNbO3/ZnO thin film multilayer on glass using atomic force microscopy
- 2003
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Ingår i: Journal of Materials Research. - 0884-2914 .- 2044-5326. ; 18:9, s. 2025-2028
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Tidskriftsartikel (refereegranskat)abstract
- A LiNbO3/ZnO multilayer with a preferred c-axis orientation normal to the plane of the substrate was grown on glass and SiO2/Si substrates by laser ablation. The piezoelectric activity in as-deposited films was demonstrated using a novel approach to the atomic force microscope. In the presence of an in-plane, low-frequency (0.1-5 Hz) alternating current electric field, we monitored and imaged the induced piezoelectric response normal to the film plane between two electrodes.
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