Conceptual design of single turbofan engine powered light aircraft

The conceptual design of a four place single turbofan engine powered light aircraft was accomplished utilizing contemporary light aircraft conventional design techniques as a means of evaluating the NASA-Ames General Aviation Synthesis Program (GASP) as a preliminary design tool. In certain areas, disagreement or exclusion were found to exist between the results of the conventional design and GASP processes. Detail discussion of these points along with the associated contemporary design methodology are presented

Evaluation of the urban design storm concept

This report describes an evaluation of the assumption commonly employed in drainage design that the return period of the rainfall used to design a system is the same as the peak flow produced by that rainfall. Specifically, the sensitivity of the frequency response of four catchments to design storm parameters is examined. Parameters include, hyetograph shape, antecedent soil moisture and rainfall duration. A continuous simulation model is used to compute simulated historical frequency responses for three different long term rainfall records. Design storms are also developed from depth-duration-frequency analyses of the rainfall data. Comparisons are made on frequency graphs. It is concluded that an appropriate choice of design storm parameters can produce a design which yields peak flows of the desired return period.U.S. Department of the InteriorU.S. Geological SurveyOpe

An integrated approach to rotorcraft human factors research

As the potential of civil and military helicopters has increased, more complex and demanding missions in increasingly hostile environments have been required. Users, designers, and manufacturers have an urgent need for information about human behavior and function to create systems that take advantage of human capabilities, without overloading them. Because there is a large gap between what is known about human behavior and the information needed to predict pilot workload and performance in the complex missions projected for pilots of advanced helicopters, Army and NASA scientists are actively engaged in Human Factors Research at Ames. The research ranges from laboratory experiments to computational modeling, simulation evaluation, and inflight testing. Information obtained in highly controlled but simpler environments generates predictions which can be tested in more realistic situations. These results are used, in turn, to refine theoretical models, provide the focus for subsequent research, and ensure operational relevance, while maintaining predictive advantages. The advantages and disadvantages of each type of research are described along with examples of experimental results

No need to justify your choice: pre-compiling line breaks to improve eBook readability

Implementations of eBooks have existed in one form or another for at least the past 20 years, but it is only in the past 5 years that dedicated eBook hardware has become a mass-market item. New screen technologies, such as e-paper, provide a reading experience similar to those of physical books, and even backlit LCD and OLED displays are beginning to have high enough pixel densities to render text crisply at small point sizes. Despite this, the major element of the physical book that has not yet made the transition to the eBook is high-quality typesetting. The great advantage of eBooks is that the presentation of the page can adapt, at rendering time, to the physical screen size and to the reading preferences of the user. Until now, simple first-fit linebreaking algorithms have had to be used in order to give acceptable rendering speed whilst conserving battery life. This paper describes a system for producing well-typeset, scalable document layouts for eBook readers, without the computational overhead normally associated with better-quality typesetting. We precompute many of the complex parts of the typesetting process, and perform the majority of the ‘heavy lifting’ at document compile-time, rather than at rendering time. Support is provided for floats (such as figures in an academic paper, or illustrations in a novel), for arbitrary screen sizes, and also for arbitrary point-size changes within the text

Regular and Chaotic Motion in General Relativity: The Case of a Massive Magnetic Dipole

Circular motion of particles, dust grains and fluids in the vicinity of compact objects has been investigated as a model for accretion of gaseous and dusty environment. Here we further discuss, within the framework of general relativity, figures of equilibrium of matter under the influence of combined gravitational and large-scale magnetic fields, assuming that the accreted material acquires a small electric charge due to interplay of plasma processes and photoionization. In particular, we employ an exact solution describing the massive magnetic dipole and we identify the regions of stable motion. We also investigate situations when the particle dynamics exhibits the onset of chaos. In order to characterize the measure of chaoticness we employ techniques of Poincar\'e surfaces of section and of recurrence plots.Comment: 11 pages, 6 figures, published in the proceedings of the conference "Relativity and Gravitation: 100 Years after Einstein in Prague" (25. - 29. 6. 2012, Prague

Locating bugs without looking back

Bug localisation is a core program comprehension task in software maintenance: given the observation of a bug, e.g. via a bug report, where is it located in the source code? Information retrieval (IR) approaches see the bug report as the query, and the source code files as the documents to be retrieved, ranked by relevance. Such approaches have the advantage of not requiring expensive static or dynamic analysis of the code. However, current state-of-the-art IR approaches rely on project history, in particular previously fixed bugs or previous versions of the source code. We present a novel approach that directly scores each current file against the given report, thus not requiring past code and reports. The scoring method is based on heuristics identified through manual inspection of a small sample of bug reports. We compare our approach to eight others, using their own five metrics on their own six open source projects. Out of 30 performance indicators, we improve 27 and equal 2. Over the projects analysed, on average we find one or more affected files in the top 10 ranked files for 76% of the bug reports. These results show the applicability of our approach to software projects without history

A simulated study of implicit feedback models

In this paper we report on a study of implicit feedback models for unobtrusively tracking the information needs of searchers. Such models use relevance information gathered from searcher interaction and can be a potential substitute for explicit relevance feedback. We introduce a variety of implicit feedback models designed to enhance an Information Retrieval (IR) system's representation of searchers' information needs. To benchmark their performance we use a simulation-centric evaluation methodology that measures how well each model learns relevance and improves search effectiveness. The results show that a heuristic-based binary voting model and one based on Jeffrey's rule of conditioning [5] outperform the other models under investigation

Molecular basis of retinol anti‐ageing properties in naturally aged human skin in vivo

ObjectiveRetinoic acid has been shown to improve the aged‐appearing skin. However, less is known about the anti‐ageing effects of retinol (ROL, vitamin A), a precursor of retinoic acid, in aged human skin in vivo. This study aimed to investigate the molecular basis of ROL anti‐ageing properties in naturally aged human skin in vivo.MethodsSun‐protected buttock skin (76 ± 6 years old, n = 12) was topically treated with 0.4% ROL and its vehicle for 7 days. The effects of topical ROL on skin epidermis and dermis were evaluated by immunohistochemistry, in situ hybridization, Northern analysis, real‐time RT‐PCR and Western analysis. Collagen fibrils nanoscale structure and surface topology were analysed by atomic force microscopy.ResultsTopical ROL shows remarkable anti‐ageing effects through three major types of skin cells: epidermal keratinocytes, dermal endothelial cells and fibroblasts. Topical ROL significantly increased epidermal thickness by stimulating keratinocytes proliferation and upregulation of c‐Jun transcription factor. In addition to epidermal changes, topical ROL significantly improved dermal extracellular matrix (ECM) microenvironment; increasing dermal vascularity by stimulating endothelial cells proliferation and ECM production (type I collagen, fibronectin and elastin) by activating dermal fibroblasts. Topical ROL also stimulates TGF‐β/CTGF pathway, the major regulator of ECM homeostasis, and thus enriched the deposition of ECM in aged human skin in vivo. 0.4% topical ROL achieved similar results as seen with topical retinoic acid, the biologically active form of ROL, without causing noticeable signs of retinoid side effects.Conclusion0.4% topical ROL shows remarkable anti‐ageing effects through improvement of the homeostasis of epidermis and dermis by stimulating the proliferation of keratinocytes and endothelial cells, and activating dermal fibroblasts. These data provide evidence that 0.4% topical ROL is a promising and safe treatment to improve the naturally aged human skin.RésuméObjectifL’acide rétinoïque a été montré améliorer l’apparence de la peau âgée. Cependant, on connaît moins les effets anti‐vieillissement de rétinol (ROL, de la vitamine A), un précurseur de l’acide rétinoïque, dans la peau humaine in vivo. Cette étude visait à étudier la base moléculaire des propriétés anti‐vieillissement du retinol de la peau humaine naturellement vieillie in vivo.MethodesLa peau des fesses protégée des UV (76 ± 6 ans, n = 12) a été traitée par voie topique avec 0,4% ROL et son véhicule pendant sept jours. Les effets du ROL topique sur l’épiderme et le derme de la peau ont été évalués par immunohistochimie, l’hybridation in situ, l’analyse Northern, RT‐PCR en temps réel, et analyse Western. La structure des fibrilles de collagène à l’échelle nanométrique et la topologie de surface ont été analysés par microscopie à force atomique.RésultatsROL par voie topique montre des effets anti‐âge remarquables à travers trois grands types de cellules de la peau: les kératinocytes épidermiques, les cellules endothéliales et les fibroblastes dermiques. ROL topique augmente de manière significative l’épaisseur de l’épiderme en stimulant la prolifération des kératinocytes et une régulation positive du facteur de transcription c‐Jun. En plus des changements de l’épiderme, le ROL topique améliore significativement le microenvironnement de la matrice extracellulaire (ECM) dermique: augmentation de la vascularisation cutanée par stimulation de la prolifération des cellules endothéliales et la production d’ECM (collagène de type I, la fibronectine et l’élastine), en activant les fibroblastes dermiques. Le ROL topique stimule également la voie TGF‐β / CTGF, le principal régulateur de l’homéostasie ECM, et donc enrichit le dépôt d’ECM dans la peau âgée humaine in vivo. L’application topique de 0,4% ROL obtient des résultats similaires à ceux observés avec l’acide rétinoïque topique, la forme biologiquement active de ROL, sans provoquer de signes apparents d’effets secondaires associés aux rétinoïdes.ConclusionL’application topique de 0,4% ROL montre des effets remarquables anti‐âge grâce à une amélioration de l’homéostasie du derme et l’épiderme, en stimulant la prolifération des kératinocytes et des cellules endothéliales, et l’activation des fibroblastes dermiques. Ces données fournissent la preuve que l’application topique de 0,4% ROL est un traitement prometteur et sûr pour améliorer la peau humaine vieillie naturellement.Topical application of 0.4% ROL to aged human skin leads to remarkable skin changes in both epidermis and dermis through affecting three major types of skin cells, epidermal keratinocytes, dermal endothelial cells and fibroblasts.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/136029/1/ics12348.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/136029/2/ics12348_am.pd

Controlling crystal symmetries in phase-field crystal models

We investigate the possibility to control the symmetry of ordered states in phase-field crystal models by tuning nonlinear resonances. In two dimensions, we find that a state of square symmetry as well as coexistence between squares and hexagons can be easily obtained. In contrast, it is delicate to obtain coexistence of squares and liquid. We develop a general method for constructing free energy functionals that exhibit solid-liquid coexistence with desired crystal symmetries. As an example, we develop a free energy functional for square-liquid coexistence in two dimensions. A systematic analysis for determining the parameters of the necessary nonlinear terms is provided. The implications of our findings for simulations of materials with simple cubic symmetry are discussed.Comment: 19 pages, 6 figure