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81.
Michael J. Hill Udaya Senarath Alex Lee Melanie Zeppel Joanne M. Nightingale Tim R. McVicar 《Remote sensing of environment》2006,101(4):495-518
The leaf area index (LAI) product from the Moderate Resolution Imaging Spectroradiometer (MODIS) is important for monitoring and modelling global change and terrestrial dynamics at many scales. The algorithm relies on spectral reflectances and a six biome land cover classification. Evaluation of the specific behaviour and performance of the product for regions of the globe such as Australia are needed to assist with product refinement and validation. We made an assessment of Collection 4 of the MODIS LAI product using four approaches: (a) assessment against a continental scale Structural Classification of Australian Vegetation (SCAV); (b) assessment against a continental scale land use classification (LUC); (c) assessment against historical field-based measurement of LAI collected prior to the Terra Mission; and (d) direct comparison of MODIS LAI with coincident field measurements of LAI, mostly from hemispherical photography. The MODIS LAI product produced a wide variety of geographically and structurally specific temporal response profiles between different classes and even for sub-groups within classes of the SCAV. Historical and concurrent field measurements indicated that MODIS LAI was giving reasonable estimates for LAI for most cover types and land use types, but that major overestimation of LAI occurs in some eastern Australian open forests and woodlands. The six biome structural land cover classification showed some significant deviations in class allocation compared to the SCAV particularly where grasslands are allocated to shrubland, savanna woodlands are allocated to shrubland, savanna and broadleaf forest, and open forests are allocated to savanna and broadleaf forest. The land cover and LAI products could benefit from some additional examination of Australian data addressing the structural representation of Eucalypt canopies in the “space of canopy realisation” for savanna and broadleaf forest classes. 相似文献
82.
Even though reverberation chambers have been used primarily for radiated immunity testing, they are reciprocal devices that are equally applicable for radiated emissions testing. This short paper presents the theory for radiated emissions testing and uses electromagnetic reciprocity theory to demonstrate the link between radiated emissions and immunity testing. 相似文献
83.
Marwa Louleb Ismael Galvn Latifa Latrous Nicholas M. Justyn Geoffrey E. Hill ngel Ríos Mohammed Zougagh 《International journal of molecular sciences》2022,23(11)
Unlike humans, some animals have evolved a physiological ability to deposit porphyrins, which are pigments produced during heme synthesis in cells, in the skin and associated integument such as hair. Given the inert nature and easiness of collection of hair, animals that present porphyrin-based pigmentation constitute unique models for porphyrin analysis in biological samples. Here we present the development of a simple, rapid, and efficient analytical method for four natural porphyrins (uroporphyrin I, coproporphyrin I, coproporphyrin III and protoporphyrin IX) in the Southern flying squirrel Glaucomys volans, a mammal with hair that fluoresces and that we suspected has porphyrin-based pigmentation. The method is based on capillary liquid chromatography-mass spectrometry (CLC-MS), after an extraction procedure with formic acid and acetonitrile. The resulting limits of detection (LOD) and quantification (LOQ) were 0.006–0.199 and 0.021–0.665 µg mL−1, respectively. This approach enabled us to quantify porphyrins in flying squirrel hairs at concentrations of 3.6–353.2 µg g−1 with 86.4–98.6% extraction yields. This method provides higher simplicity, precision, selectivity, and sensitivity than other methods used to date, presenting the potential to become the standard technique for porphyrin analysis. 相似文献
84.
Image segmentation using a texture gradient based watershed transform 总被引:13,自引:0,他引:13
The segmentation of images into meaningful and homogenous regions is a key method for image analysis within applications such as content based retrieval. The watershed transform is a well established tool for the segmentation of images. However, watershed segmentation is often not effective for textured image regions that are perceptually homogeneous. In order to segment such regions properly, the concept of the "texture gradient" is introduced. Texture information and its gradient are extracted using a novel nondecimated form of a complex wavelet transform. A novel marker location algorithm is subsequently used to locate significant homogeneous textured or non textured regions. A marker driven watershed transform is then used to segment the identified regions properly. The combined algorithm produces effective texture and intensity based segmentation for application to content based image retrieval. 相似文献
85.
Gillian B. Greenhill 《History of Photography》2013,37(3):199-205
Abstract It seems destiny that all that is connected with the young British poet, Thomas Chatterton, must be filled with controversy. The furore which arose concerning his publication of the Rowley poems was only intensified by the writer's untimely death. 相似文献
86.
Jason K. Freels Joseph J. Pignatiello Richard L. Warr Raymond R. Hill 《Quality and Reliability Engineering International》2015,31(5):789-800
Test planners have long sought the ability to incorporate the results of highly accelerated life testing (HALT) into an early estimate of system reliability. While case studies attest to the effectiveness of HALT in producing reliable products, the capability to translate the test's limited failure data into a meaningful measure of reliability improvement remains elusive. Further, a review of quality and reliability literature indicates that confusion exists over what defines a HALT and how HALT differs from quantitative accelerated life testing methods. Despite many authors making a clear distinction between qualitative and quantitative accelerated life tests, an explanation as to why this delineation exists cannot be found. In this paper, we consider an exemplary HALT composed of a single stressor to show that the HALT philosophy precludes the estimation of a system's hazard rate function parameters because of the test's fix implementation strategy. Four common accelerated failure data analysis methods are highlighted to show their limitations with respect to estimating reliability from HALT data. Finally, a modified accelerated reliability growth test is proposed as a way forward for future research in HALT scenarios to characterize the risk of attaining a reliability requirement and improve parameter estimation. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
87.
David R. Hill 《Journal of the American Planning Association. American Planning Association》2013,79(3):302-314
Over the last quarter-century Jane Jacobs has developed the argument that the dense central areas of large cities are both quality living environments and the indispensable hatchery of new jobs and economic advances for society as a whole. Her most recent book, Cities and the Wealth of the Nations, extends her earlier urban design and economic thought to the regional, national, and international scales, and it completes the sketch of a general theory of planning. Despite her great popularity, her many formulations have not been summarized for professional planning audiences, located in the context of other planning ideas, or assessed for theoretical quality. This article addresses each of those topics. I find her theoretical strengths to be originality, emotional force, style, and timeliness. I give her mixed reviews for completeness, consistency, equity, technical design, and impact. Her weakest areas are in strategic detail, empirical verifiability, and documentation. 相似文献
88.
Glen Hill 《Architectural Theory Review》2013,18(2):72-88
Earlier this year I was asked to give a talk about historical research to a research methods class being held for graduate research students in their probationary year. This paper is an outcome of that presentation. The paper attempts to illustrate the polarities evident in contemporary historiography and, where possible, to draw out their implications for architectural history research. Because of its pedagogical context, the contours of the debate are deliberately accentuated and the resolution (within a Heideggerian framework) overtly formulaic. Despite this lack of subtlety (or perhaps because of it?) the approach appeared to work effectively in fostering student engagement with the current debate. ...I understand the postmodern predicament to imply no-thingness. No-thing out there to substantiate. No ‘there, there’ to represent. Therefore postmodern history implies no story, no narrative, no interpretation and no explanation.1 相似文献
89.
Zhenping Liu Alberto Passalacqua Michael G. Olsen Rodney O. Fox James C. Hill 《American Institute of Chemical Engineers》2016,62(7):2570-2578
The multi‐inlet vortex reactor (MIVR) is used for flash nanoprecipitation to manufacture functional nanoparticles. A validated computational fluid dynamics model is needed for the design, scale‐up, and optimization of the MIVR. Unfortunately, available Reynolds‐averaged Navier‐Stokes methods are unable to accurately model the highly swirling flow in the MIVR. Large‐eddy simulations (LES) are also problematic, as excessively fine grids are required to accurately model this flow. These dilemmas led to the application of the dynamic delayed detached eddy simulation (DDES) method to the MIVR. In the dynamic DDES model, the eddy viscosity has a form similar to the Smagorinsky sub‐grid viscosity in LES, which allows the implementation of a dynamic procedure to determine its model coefficient. Simulation results using the dynamic DDES model are found to match well with experimental data in terms of mean velocity and turbulence intensity, suggesting that the dynamic DDES model is a good option for modeling the turbulent swirling flow in the MIVR. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2570–2578, 2016 相似文献
90.
Limin Dong David J. T. Hill James H. O'Donnell Peter J. Pomery Koichi Hatada 《应用聚合物科学杂志》1996,59(4):589-597
The γ irradiation of poly(methacrylate)s with various ester groups at room temperature was investigated by gel permeation chromatography and NMR techniques. The G values for scission and crosslinking for each of the polymers were estimated from the changes in the molecular weights and molecular weight distributions. The new structures formed during γ irradiation were examined by 1H-NMR spectroscopy. All of the investigated poly(alkanemethacrylate)s were found to produce the alkane formates during γ irradiation, and for poly(2-methyl heptyl methacrylate) G(S) was less than 4G(X), indicating gel formation in this polymer. In the investigation of poly(benzyl methacrylate), no formate ester was found, but some small molecule compounds formed from the benzyl radical were detected. The benzyl group was also found to stabilize the polymer against radiation damage. © 1996 John Wiley & Sons, Inc. 相似文献