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61.
Aylin Kantarcı 《Multimedia Systems》2010,16(6):381-397
Real-time delivery of medical videos requires high level of quality of service that shows no tolerance to loss and delay.
In this study, how content-adaptive streaming can aid to maintain high-quality streaming sessions is investigated. The proposed
strategy allocates a specific amount of bandwidth to streaming sessions and takes advantage of the general structure of instructional
medical videos to decrease bandwidth consumption below this limit. The main contribution of the proposed mechanism is that
it eliminates the need for rate adaptation which is common in traditional streaming by employing a proper bandwidth management
scheme that enables constant bandwidth consumption below the allocated capacity. A streaming system based on the proposed
mechanism has been implemented and its performance has been tested via emulation. Experimental results indicate that content-adaptive
streaming successfully eliminates the need of rate adaptation during the delivery of critical data and hence preserves viewers’
satisfaction. 相似文献
62.
Mustafa Sarıdemir 《Expert systems with applications》2011,38(11):14257-14268
Compressive strength and splitting tensile strength are both mechanical properties of concrete that are utilized in structural design. This study presents gene expression programming (GEP) as a new tool for the formulations of splitting tensile strength from compressive strength of concrete. For purpose of building the GEP-based formulations, 536 experimental data have been gathered from existing literature. The GEP-based formulations are developed for splitting tensile strength of concrete as a function of age of specimen and cylinder compressive strength. In experimental parts of this study, cylindrical specimens of 150 × 300 mm and 100 × 200 mm in dimensions are utilized. Training and testing sets of the GEP-based formulations are randomly separated from the complete experimental data. The GEP-based formulations are also validated with additional 173 data of experimental results other than the data used in training and testing sets of the GEP-based formulations. All of the results obtained from the GEP-based formulations are compared with the results obtained from experimental data, the developed regression-based formulation and formulas given by some national building codes. These comparisons showed that the GEP-based formulations appeared to well agree with the experimental data and found to be quite reliable. 相似文献
63.
In this paper, regression analyses (RA) are presented for the neutronic calculation of ThO2 mixed 244CmO2 fuel with different neutronic parameters for various coolants, natural lithium, Li20Sn80 and Flinabe, respectively. The tritium breeding ratio (TBR), energy multiplication factor (M), total fission rate (Σf) and 232Th(n, γ) reaction is computed by XSDRNPM. In addition, this numerical results are estimated by RA depends on neutronic parameters and the empirical equations for neutronic performance are acquired. The results obtained by using XSDRNPM and the results of the RA, obtained empirical equations, are compared. The empirical equations indicate that RA can successfully be used for the prediction of the neutronic performance parameters in the hybrid reactor with a high degree of accuracy. In addition, correlation matrix is calculated to determined statistical relationships between variables TBR, M, Σf, and 232Th(n, γ). 相似文献
64.
The interactive whiteboard (IWB) has become a popular technology for instructors over the last decade. Though research asserts that the IWBs facilitate learning in different ways, there is a lack of studies examining actual IWB use in classroom settings based on learners’ perspectives by means of valid instruments. The purpose of this study is to develop a valid and reliable interactive whiteboard student survey in order to evaluate the IWB use based on perceptions of students who have been taught with IWBs. In establishing the theoretical base of the survey, the Technology Acceptance Model (TAM) and constructivist learning theories were considered. In addition, with respect to IWB use in classrooms, a number of studies emanated from countries such as the UK, the USA, and Australia were examined, and similar research questionnaires and findings and also reflections of students about IWBs were utilized to create an item pool. A 39-item survey was conducted among middle school students (N = 263) from the city of Istanbul in Turkey. Collected data was exposed to exploratory factor analysis and resulted in a 26-item, three-factor survey, whose factors were named as the perceived efficiency of IWB, perceived learning contribution and motivation, and the perceived negative effects of IWB. The results of the analyses illustrated that this new IWB student scale, which explains 50% of the total variance with a good level of Cronbach’s Alpha coefficient (0.93) is a valid and reliable instrument designed specifically for measuring the use of IWBs in real classroom settings. Besides, theoretical foundations of interactive whiteboard use, the development process of the instrument, and results of validity and reliability analyses were discussed in detail. 相似文献
65.
We present a single-machine problem with the unequal release times under learning effect and deteriorating jobs when the objective is minimizing the makespan. In this study, we introduced a scheduling model with unequal release times in which both job deterioration and learning exist simultaneously. By the effects of learning and deterioration, we mean that the processing time of a job is defined by increasing function of its execution start time and position in the sequence. A branch-and-bound algorithm incorporating with several dominance properties and lower bounds is developed to derive the optimal solution. A heuristic algorithm is proposed to obtain a near-optimal solution. The computational experiments show that the branch-and-bound algorithm can solve instances up to 30 jobs, and the average error percentage of the proposed heuristic is less than 0.16%. 相似文献
66.
67.
Soft groups and normalistic soft groups 总被引:1,自引:0,他引:1
Soft set theory, proposed by Molodtsov, has been regarded as an effective mathematical tool to deal with uncertainties. In this paper, first we correct some of the problematic cases in a previous paper by Akta? and Çag˜man [H. Akta?, N. Çag˜man, Soft sets and soft groups, Inf. Sci. 177 (2007) 2726-2735]. Moreover, we introduce the concepts of normalistic soft group and normalistic soft group homomorphism, study their several related properties, and investigate some structures that are preserved under normalistic soft group homomorphisms. 相似文献
68.
Autonomous use of legged robots in unstructured, outdoor settings requires dynamically dexterous behaviors to achieve sufficient
speed and agility without overly complex and fragile mechanics and actuation. Among such behaviors is the relatively under-studied
pronking (aka. stotting), a dynamic gait in which all legs are used in synchrony, usually resulting in relatively slow speeds but
long flight phases and large jumping heights. Instantiations of this gait for robotic systems have been mostly limited to
open-loop strategies, suffering from severe pitch instability for underactuated designs due to the lack of active feedback.
However, both the kinematic simplicity of this gait and its dynamic nature suggest that the Spring-Loaded Inverted Pendulum
model (SLIP) would be a good basis for the implementation of a more robust feedback controller for pronking. In this paper,
we describe how template-based control, a controller structure based on the embedding of a simple dynamical “template” within a more complex “anchor” system, can
be used to achieve very stable pronking for a planar, underactuated hexapod robot. In this context, high-level control of
the gait is regulated through speed and height commands to the SLIP template, while the embedding controller ensures the stability
of the remaining degrees of freedom. We use simulation studies to show that unlike existing open-loop alternatives, the resulting
control structure provides explicit gait control authority and significant robustness against sensor and actuator noise. 相似文献
69.
In this paper, a novel classification rule extraction algorithm which has been recently proposed by authors is employed to
determine the causes of quality defects in a fabric production facility in terms of predetermined parameters like machine
type, warp type etc. The proposed rule extraction algorithm works on the trained artificial neural networks in order to discover
the hidden information which is available in the form of connection weights in them. The proposed algorithm is mainly based
on a swarm intelligence metaheuristic which is known as Touring Ant Colony Optimization (TACO). The algorithm has a hierarchical
structure with two levels. In the first level, a multilayer perceptron type neural network is trained and its weights are
extracted. After obtaining the weights, in the second level, the TACO-based algorithm is applied to extract classification
rules. The main purpose of the present work is to determine and analyze the most effective parameters on the quality defects
in fabric production. The parameters and their levels which give the best quality results are tried to be discovered and evaluated
by making use of the proposed algorithm. It is also aimed to compare the accuracy of proposed algorithm with several other
rule-based algorithms in order to present its competitiveness. 相似文献
70.
This paper targets at the problem of automatic semantic indexing of news videos by presenting a video annotation and retrieval system which is able to perform automatic semantic annotation of news video archives and provide access to the archives via these annotations. The presented system relies on the video texts as the information source and exploits several information extraction techniques on these texts to arrive at representative semantic information regarding the underlying videos. These techniques include named entity recognition, person entity extraction, coreference resolution, and semantic event extraction. Apart from the information extraction components, the proposed system also encompasses modules for news story segmentation, text extraction, and video retrieval along with a news video database to make it a full-fledged system to be employed in practical settings. The proposed system is a generic one employing a wide range of techniques to automate the semantic video indexing process and to bridge the semantic gap between what can be automatically extracted from videos and what people perceive as the video semantics. Based on the proposed system, a novel automatic semantic annotation and retrieval system is built for Turkish and evaluated on a broadcast news video collection, providing evidence for its feasibility and convenience for news videos with a satisfactory overall performance. 相似文献