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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Numerical simulation of the hydraulic performances and flow pattern of swallow-tailed flip bucket

Zhang, L., Zhang, J., Guo, Yakun, Peng, Y. 20 April 2020 (has links)
Yes / In this study, the evolution process of the swallow-tailed flip bucket water nappe entering into the plunge pool is simulated by using the standard 𝑘-𝜀 turbulence model and the volume of fluid method. The effects of the upstream opening width ratio and downstream bucket angle on the flow pattern, the unit discharge distribution and the impact pressure distribution are studied. Based on the numerical results, the inner and outer jet trajectories are proposed by using the data. Results show that the longitudinal stretching length decreases with the increase of the upstream opening width ratio, and increases with the increase of the downstream bucket angle. The water nappe enters the plunge pool in a long strip shape. Thus, the unit discharge distribution of water nappe entry is consistent with the pressure distribution at the plunge pool bottom. The upstream opening width ratio and downstream bucket angle should be chosen as their intermediate values in order to have a uniform discharge distribution and to reduce the pressure peak at the plunge pool floor, which is effectively to avoid instability and destruction of plunge pool floor. / National Science Fund for Distinguished Young Scholars (No. 51625901) and National Nature Science Foundation of China (No: 51579165).
52

The energetic consequences of tail loss to juvenile lizards

Fredericksen, Nell Jefferson 08 September 2012 (has links)
l evaluated the hypothesis that juveniles of species whose tail is important for predator deflection should allocate energy preferentially to tail growth at the expense of body growth. Relative linear tail growth (linear tail growth/linear body growth) and relative mass tail growth (tail mass growth/body mass growth) were measured for juveniles of two species of skinks: <u>Eumeces Fasciatus</u> that use the tail for predator deflection, and <u>Chalcides ocellatus</u> that does not use the tail for predator deflection. Experimental conditions produced an energy limiting situation under which the priority of energy allocation to tail regeneration should be exhibited. For <u>E. fasciatus</u>, relative linear tail growth was higher for the energy limited than control group and for the tail-removal than the tailed lizards. For <u>C. ocellatus</u>, relative linear tail growth was not affected by energy level but was lower for tail-removal than tailed lizards. For both species, relative tail mass growth was lower for the tail-removal than tailed lizards. The greater relative linear tail growth of regenerating than normal tails of <u>E. fasciatus</u> supports the hypothesis that rapid tail regeneration is important for a species whose tail is used for predator deflection. However, the low rate of tail regenerartion in mass suggests that mass gains in the regeneration process. In contrast, lower relative linear and mass tail growth of <u>C. ocellatus</u> that were regenerating tails suggests that tail regeneration has a low priority for this species. / Master of Science
53

Evaluation of Word Length Effects on Multistandard Soft Decision Viterbi Decoding

Salim, Ahmed January 2011 (has links)
There have been proposals of many parity inducing techniques like Forward ErrorCorrection (FEC) which try to cope the problem of channel induced errors to alarge extent if not completely eradicate. The convolutional codes have been widelyidentified to be very efficient among the known channel coding techniques. Theprocess of decoding the convolutionally encoded data stream at the receiving nodecan be quite complex, time consuming and memory inefficient.This thesis outlines the implementation of multistandard soft decision viterbidecoder and word length effects on it. Classic Viterbi algorithm and its variantsoft decision viterbi algorithm, Zero-tail termination and Tail-Biting terminationfor the trellis are discussed. For the final implementation in C language, the "Zero-Tail Termination" approach with soft decision Viterbi decoding is adopted. Thismemory efficient implementation approach is flexible for any code rate and anyconstraint length.The results obtained are compared with MATLAB reference decoder. Simulationresults have been provided which show the performance of the decoderand reveal the interesting trade-off of finite word length with system performance.Such investigation can be very beneficial for the hardware design of communicationsystems. This is of high interest for Viterbi algorithm as convolutional codes havebeen selected in several famous standards like WiMAX, EDGE, IEEE 802.11a,GPRS, WCDMA, GSM, CDMA 2000 and 3GPP-LTE.
54

Os sistemas de recomendação como instrumento para atingir mercados de nicho

Nodari, Antonio Regis 09 May 2008 (has links)
O objetivo deste trabalho é estudar o efeito dos sistemas de recomendação em um site de vinhos, verificando se os resultados estão de acordo com a teoria long tail. Esta proposição prevê que em mercados online, os produtos de nicho podem representar uma parcela significativa do resultado de uma empresa. Uma das formas de explorar estas fontes de receitas é pelo uso adequado de sistemas de recomendação que auxiliem o consumidor a encontrar o que deseja. Neste trabalho são efetuados dois estudos de caso, o primeiro utiliza o coeficiente Gini para comparar a distribuição das vendas de duas empresas, sendo uma delas de comércio eletrônico, o segundo estudo de caso seleciona quatro tipos de sistemas de recomendação e compara seus desempenhos na sugestão de vinhos. Os resultados indicam que ocorre um comportamento do tipo long tail nas vendas da loja virtual e que os sistemas de recomendação baseados nos gostos de outras pessoas são os preferidos. / Submitted by Marcelo Teixeira (mvteixeira@ucs.br) on 2014-05-20T19:24:51Z No. of bitstreams: 1 Dissertacao Antonio Regis Nodari.pdf: 1570446 bytes, checksum: 4592a5c6268d0bfe3c10cd8a58315c8f (MD5) / Made available in DSpace on 2014-05-20T19:24:51Z (GMT). No. of bitstreams: 1 Dissertacao Antonio Regis Nodari.pdf: 1570446 bytes, checksum: 4592a5c6268d0bfe3c10cd8a58315c8f (MD5)
55

Os sistemas de recomendação como instrumento para atingir mercados de nicho

Nodari, Antonio Regis 09 May 2008 (has links)
O objetivo deste trabalho é estudar o efeito dos sistemas de recomendação em um site de vinhos, verificando se os resultados estão de acordo com a teoria long tail. Esta proposição prevê que em mercados online, os produtos de nicho podem representar uma parcela significativa do resultado de uma empresa. Uma das formas de explorar estas fontes de receitas é pelo uso adequado de sistemas de recomendação que auxiliem o consumidor a encontrar o que deseja. Neste trabalho são efetuados dois estudos de caso, o primeiro utiliza o coeficiente Gini para comparar a distribuição das vendas de duas empresas, sendo uma delas de comércio eletrônico, o segundo estudo de caso seleciona quatro tipos de sistemas de recomendação e compara seus desempenhos na sugestão de vinhos. Os resultados indicam que ocorre um comportamento do tipo long tail nas vendas da loja virtual e que os sistemas de recomendação baseados nos gostos de outras pessoas são os preferidos.
56

Die Zielsteuerung peroxisomaler Membranproteine mit tail anchor / The targeting of peroxisomal membrane proteins with tail anchor

Büntzel, Judith 22 November 2017 (has links)
No description available.
57

Makroekonomická nejistota: vnější riziko v ceně zajištění / Macroeconomic Uncertainty: An Exogenous Risk in Reinsurance Pricing

Stehlíková, Zuzana January 2020 (has links)
The thesis focuses on the analysis of the impact of the inflation uncertainty on the reinsurance pricing, particularly on its measures of risk. Vector autoregression models are used to predict the medium-term inflation and simulate different inflation paths. The consideration of various scenarios of future inflation captured by the stochastic modelling increases the value at risk (VaR) and the tail value of risk (TVaR) of mean ceded loss to the reinsurer. The thesis founds that the inflation uncertainty measured by the stochastic inflation matters and it is important from risk management and hedging perspectives. As a result, additional loadings could be added to the price for the mitigation of the inflation risk. Although the effect of stochasticity of the future inflation is not significant on mean loss, it is the case for the risk of measures, especially for the contracts with high retention relatively to the underlying exposure. JEL Classification F12, F21, F23, H25, H71, H87 Keywords reinsurance pricing, inflation forecasting, inflation risk, long-tail line of business Title Macroeconomic Uncertainty: An Exogenous Risk in Reinsurance Pricing
58

Development of a Miniature VTOL Tail-Sitter Unmanned Aerial Vehicle

Hogge, Jeffrey V. 22 April 2008 (has links) (PDF)
The design, analysis, construction and flight testing of a miniature Vertical Take-Off and Landing (VTOL) tail-sitter Unmanned Aerial Vehicle (UAV) prototype is presented in detail. Classic aircraft design methods were combined with numerical analysis to estimate the aircraft performance and flight characteristics. The numerical analysis employed a propeller blade-element theory coupled with momentum equations to predict the influence of a propeller slipstream on the freestream flow field, then the aircraft was analyzed using 3-D vortex lifting-line theory to model finite wings immersed in the flow field. Four prototypes were designed, built, and tested and the evolution of these prototypes is presented. The final prototype design is discussed in detail. A method for sizing control surfaces for a tail-sitter was defined. The final prototype successfully demonstrated controllability both in horizontal flight and vertical flight. Significant contributions included the development of a control system that was effective in hover as well as descending vertical flight, and the development of a strong but light weight airframe. The aircraft had a payload weight fraction of 14.5% and a maximum dimension of one meter, making it the smallest tail-sitter UAV to carry a useful payload. This project is expected to provide a knowledge base for the future design of small electric VTOL tail-sitter aircraft and to provide an airframe for future use in tail-sitter research.
59

Att konstruera en frack : En kvalitativ studie om studentfrackens upplevda gränser

Lindström, Ellika January 2013 (has links)
This explorative study focuses on young, university attending males (22-27 years) and their understanding and pratice of the classic tail coat. It is based on five qvalitatively interpreted interwievs with a total of six participants, and through open questions regarding individuality and identicalness, limits and possibilities and inclusion and exclusion, a masculininty of a less contemporary hue takes shape. These conversations have revealed the tail coats potential of respresenting a male stereotype that can set a foundational and minimal standard for inclusion. Above this layer these males can then manifest and negotiate their masculine position in a homosocial hierarchy which decides the amount of passage, privilieges and confirmation of self- worth received for the wearer. These negotiation is performed by value bearing symbols (such as medallions, cordons and the like) allowed by the wearer and by the actions that systematically ensure that the lines of the tail coat are watched and unbroken. This is to preserve the priviliege of being allowed to deconstruct the unit of the tail coat, as this would be an absolute indication of achievement of the correct masculinity and the surrounding of the right spectators. The guarding of the tail coats limits lies within the tendencies of wanting to correct each other with feelings of either irritation or sympathy, a practice that seem rather unreflected by these men themselves. This pratice could be interpreted as a form of ”subjectfying” performed between these men, collectively and systematically (as well as unreflected) ensuring the image of masculinity remains unflawed. The tail coat allows the somewhat questioned homosociality to stay vital by forming a third gender sphere which is separated from the rules of the public (male) sphere and the private (female), but can still transcend and interact with these. In a society that porgressively have condemned the homosocial practice of men choosing and protecting other men in aspects regarding both work and domesticity, the third gender sphere becomes a sanctuary which can allow this structure to continue. However, these young men also experiences a duality, an awareness of the problems involved with gender exclusive contexts which could be a symptom of this homosocial sphere cracking in its surface. However, the overall experience of the tail coat and its connected contexts seems to be understood as fun and easy, neutral and uncomplicated, and the tail coat itself as an form of ”pavlovian conditioning” on the pleasantries connected to it.
60

Computational Problems In Codes On Graphs

Krishnan, K Murali 07 1900 (has links)
Two standard graph representations for linear codes are the Tanner graph and the tailbiting trellis. Such graph representations allow the decoding problem for a code to be phrased as a computational problem on the corresponding graph and yield graph theoretic criteria for good codes. When a Tanner graph for a code is used for communication across a binary erasure channel (BEC) and decoding is performed using the standard iterative decoding algorithm, the maximum number of correctable erasures is determined by the stopping distance of the Tanner graph. Hence the computational problem of determining the stopping distance of a Tanner graph is of interest. In this thesis it is shown that computing stopping distance of a Tanner graph is NP hard. It is also shown that there can be no (1 + є ) approximation algorithm for the problem for any є > 0 unless P = NP and that approximation ratio of 2(log n)1- є for any є > 0 is impossible unless NPCDTIME(npoly(log n)). One way to construct Tanner graphs of large stopping distance is to ensure that the graph has large girth. It is known that stopping distance increases exponentially with the girth of the Tanner graph. A new elementary combinatorial construction algorithm for an almost regular LDPC code family with provable Ώ(log n) girth and O(n2) construction complexity is presented. The bound on the girth is close within a factor of two to the best known upper bound on girth. The problem of linear time exact maximum likelihood decoding of tailbiting trellis has remained open for several years. An O(n) complexity approximate maximum likelihood decoding algorithm for tail-biting trellises is presented and analyzed. Experiments indicate that the algorithm performs close to the ideal maximum likelihood decoder.

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