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51.
Stephen Gilmore L��szl�� G?nczy Nora Koch Philip Mayer Mirco Tribastone D��niel Varr�� 《Software and Systems Modeling》2011,10(3):287-311
Systems based on the service-oriented architecture (SOA) principles have become an important cornerstone of the development
of enterprise-scale software applications. They are characterized by separating functions into distinct software units, called
services, which can be published, requested and dynamically combined in the production of business applications. Service-oriented
systems (SOSs) promise high flexibility, improved maintainability, and simple re-use of functionality. Achieving these properties
requires an understanding not only of the individual artifacts of the system but also their integration. In this context,
non-functional aspects play an important role and should be analyzed and modeled as early as possible in the development cycle.
In this paper, we discuss modeling of non-functional aspects of service-oriented systems, and the use of these models for
analysis and deployment. Our contribution in this paper is threefold. First, we show how services and service compositions
may be modeled in UML by using a profile for SOA (UML4SOA) and how non-functional properties of service-oriented systems can
be represented using the non-functional extension of UML4SOA (UML4SOA-NFP) and the MARTE profile. This enables modeling of
performance, security and reliable messaging. Second, we discuss formal analysis of models which respect this design, in particular
we consider performance estimates and reliability analysis using the stochastically timed process algebra PEPA as the underlying
analytical engine. Last but not least, our models are the source for the application of deployment mechanisms which comprise
model-to-model and model-to-text transformations implemented in the framework VIATRA. All techniques presented in this work
are illustrated by a running example from an eUniversity case study. 相似文献
52.
Sparse CCA using a Lasso with positivity constraints 总被引:1,自引:0,他引:1
Canonical correlation analysis (CCA) describes the relationship between two sets of variables by finding linear combinations of the variables with maximal correlation. A sparse version of CCA is proposed that reduces the chance of including unimportant variables in the canonical variates and thus improves their interpretation. A version of the Lasso algorithm incorporating positivity constraints is implemented in tandem with alternating least squares (ALS), to obtain sparse canonical variates. The proposed method is demonstrated on simulation studies and a data set from market basket analysis. 相似文献
53.
The problem of computing the chromatic number of a P
5-free graph (a graph which contains no path on 5 vertices as an induced subgraph) is known to be NP-hard. However, we show
that for every fixed integer k, there exists a polynomial-time algorithm determining whether or not a P
5-free graph admits a k-coloring, and finding one, if it does. 相似文献
54.
Some students (base group) played the Circuit Game, a 10-level computer-based learning activity intended to help students learn how electrical circuits work. Other students (competition group) played the same game but with competition features added - including a score bar showing performance on each level, the opportunity to earn one ticket per level if a performance criterion is met, and the opportunity to win a prize based on the number of tickets earned. On a retention test given after the game, the competition group remembered significantly more than the base group (d = 0.47). On an embedded transfer test constituting the final level of the game, the groups did not differ significantly. However, on the transfer test there was a significant gender by group interaction in which men performed worse in the competition group than the base group (d = −0.54) and women performed better in the competition group than the base group (d = 0.24). Overall, adding game-like features to a computer-based learning activity caused students to pay attention to game details but did not motivate students - particularly men - to learn more deeply. 相似文献
55.
A novel method for discriminating faults in model predictive control is presented. The proposed method monitors the Kalman filter innovations to detect the presence of autocorrelation, which is an indication of suboptimal state estimation. The cause of the suboptimal state estimation is diagnosed by the observability of this innovations process. This task involves determining the order of the autocorrelation present in the innovations. The proposed MPC fault discrimination method is demonstrated on a SISO process and a MIMO process. 相似文献
56.
We investigate the applicability of some novel spatial analysis techniques, developed for studies of astrophysical datasets, to the analysis of spatial point data in sedimentary basins. The techniques are evaluated and compared with standard methods using two test areas that contain large numbers of submarine pockmarks developed in distributed arrays. The familiar Ripley K and Voronoi tesselation techniques are used, and the results are then compared with those obtained using more novel techniques, the correlation length and minimal spanning tree. The correlation length technique is found to identify the precise distances at which clustering occurs more accurately, making a physical interpretation more clear than is possible using the Ripley K. The minimal spanning tree is found to be powerful at identifying the space-filling nature of the pockmark distribution, and has the advantage of being immune to edge effects. The use of these two novel techniques permits more information to be extracted from the datasets, and demonstrates clear statistically significant differences between them, which are not detectable using standard techniques. 相似文献
57.
In this paper, we study the bandwidth allocation problem for serving video requests in a mobile real-time video player system.
One of the main issues to maintain the quality of services (QoS) in mobile video playback is to ensure sufficient number of
video frames available at the client side while a video is being played. However, due to the limited bandwidth of a mobile
network and variable workload streaming video, this is not easy to achieve in practice. In addition, the communication link
between mobile clients and a video server is subject to frequent errors and temporary disconnection. In this paper, we propose
to use the notion of buffered bandwidth in addition to the network bandwidth to support real-time playback of videos at mobile clients. Based on this, we designed
a bandwidth allocation scheme called Cooperative Pre-Fetching (CP) in which the amount of bandwidth to be allocated to serve a video request depends on the current buffer level of the
video at the client relative to the target buffer level of the client. In determining the target buffer level, we consider
the errors in communication to the client as well as the other clients who are concurrently served by the system. The buffered
video frames at the clients are then used to minimize the impact of error in communications on the overall QoS of video playbacks
in the whole system.
相似文献
Kam-Yiu Lam (Corresponding author)Email: |
58.
Lina Peng K. Selçuk Candan Christopher Mayer Karamvir S. Chatha Kyung Dong Ryu 《Multimedia Tools and Applications》2007,33(3):245-272
In this paper, we present the ARIA media processing workflow architecture that processes, filters, and fuses sensory inputs
and actuates responses in real-time. The components of the architecture are programmable and adaptable; i.e. the delay, size,
and quality/precision characteristics of the individual operators can be controlled via a number of parameters. Each data
object processed by qStream components is subject to transformations based on the parameter values. For instance, the quality of an output data object
and the corresponding processing delay and resource usage depend on the values assigned to parameters of the operators in
the object flow path. In Candan, Peng, Ryu, Chatha, Mayer (Efficient stream routing in quality- and resource-adaptive flow
architectures. In: Workshop on multimedia information systems, 2004), we introduced a class of flow optimization problems that promote creation and delivery of small delay or small resource-usage objects to the actuators in single-sensor, single-actuator
workflows. In this paper, we extend our attention to multi-sensor media processing workflow scenarios. The algorithms we present
take into account the implicit dependencies between various system parameters, such as resource consumption and object sizes.
We experimentally show the effectiveness and efficiency of the algorithms.
相似文献
Kyung Dong RyuEmail: |
59.
An advanced evenly-spaced streamline placement algorithm 总被引:3,自引:0,他引:3
Liu Z Moorhead RJ Groner J 《IEEE transactions on visualization and computer graphics》2006,12(5):965-972
This paper presents an advanced evenly-spaced streamline placement algorithm for fast, high-quality, and robust layout of flow lines. A fourth-order Runge-Kutta integrator with adaptive step size and error control is employed for rapid accurate streamline advection. Cubic Hermite polynomial interpolation with large sample-spacing is adopted to create fewer evenly-spaced samples along each streamline to reduce the amount of distance checking. We propose two methods to enhance placement quality. Double queues are used to prioritize topological seeding and to favor long streamlines to minimize discontinuities. Adaptive distance control based on the local flow variance is explored to reduce cavities. Furthermore, we propose a universal, effective, fast, and robust loop detection strategy to address closed and spiraling streamlines. Our algorithm is an order-of-magnitude faster than Jobard and Lefer's algorithm with better placement quality and over 5 times faster than Mebarki et al.'s algorithm with comparable placement quality, but with a more robust solution to loop detection. 相似文献
60.
HW Klafki AI Pick I Pardowitz T Cole LA Awni HU Barnikol F Mayer HD Kratzin N Hilschmann 《Canadian Metallurgical Quarterly》1993,374(12):1117-1122
Motivated by the finding that the amino acid sequence of the Bence Jones protein BJP-DIA was identical to that of the main protein component of the amyloid fibrils obtained from the same patient with AL-amyloidosis, (Klafki, H.-W., Kratzin, H.-D., Pick, A.-I., Eckart, K., Karas, M. & Hilschmann, N. (1992) Biochemistry 31, 3265-3272.), we attempted to create "amyloid-like" fibrils from the Bence Jones protein in vitro, without addition of proteolytic enzymes. Reduction of BJP-DIA, solubilized in PBS, pH 7.4, overnight at 37 degrees C resulted in the formation of a precipitate which had affinity for the dye Congo red. Electron microscopy of negatively stained samples of the reduced protein revealed aggregates of linear unbranched fibrils. SDS-polyacrylamide gel electrophoresis demonstrated that the precipitate consisted almost exclusively of intact light chain molecules. This result makes it possible to deduce a molecular model of these amyloid fibrils generated in vitro. 相似文献