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We evaluate the performance of a cloud system using ahysteresis queueing system with phase-type and batch arrivals. To represent the dynamic allocation of the resources, the hysteresis queueactivates and deactivates the virtual machines according to the threshold values of the queue length. We suppose a variable traffic intensity as the client requests (or jobs) arrive by batches, and follow a phase-type...
We present TerrainLOS, an outdoor propagation model that uses Digital Elevation Models to determine whether two nodes can communicate. We have implemented TerrainLOS in the sensor network simulator COOJA and used it to evaluate how the roughness of terrain, which we classify using Average Cumulative Visibility, affects the number of edges, connectedness, latency, and power of a network. We compare...
The chunk fragmentation problem inherently associated with deduplication systems significantly slows down the restore performance, as it causes the restore process to assemble chunks which are distributed in a large number of containers as a result of storage indirection. Existing solutions attempting to address the fragmentation problem either sacrifice deduplication efficiency or require additional...
Recent computer systems research has proposed using redundant requests to reduce latency. The idea is to replicate a request so that it joins the queue at multiple servers. The request is considered complete as soon as any one copy of the request completes. Redundancy is beneficial because it allows us to overcome server-side variability – the fact that the server we choose might be temporarily slow...
Live Virtual Machine (VM) migration across data centers is an important support technology which will bring benefits to both cloud providers and users. At present, VM storage migration becomes the bottleneck of this technology as it explores only the static data feature of image files without much consideration on data semantics. In this paper, we propose a new space-efficient VM image structure–three-layer...
In digital game based learning (DGBL), game mechanics and learning mechanics define the interactivity possibilities between the player and the game. While game and learning mechanics can facilitate the design and development of DGBL activities, they have not yet been analyzed from the perspective of the learning theories underlying the type of interactions between the player and the game. This study...
The paper analyses the analytical models of fatigue and their applicability for using natural user interfaces (NUI). For evaluation of eye fatigue we use a gaze speller as an example of NUI system for text input with human gaze and eye tracking device. We use the system to evaluate the state and performance of the users in performing the text entry task as well as to analyse dynamical changes of the...
An important and widespread topic in cloud computing is text analyzing. People often use topic model which is a popular and effective technology to deal with related tasks. Among all the topic models, sLDA is acknowledged as a popular supervised topic model, which adds a response variable or category label with each document, so that the model can uncover the latent structure of a text dataset as...
In this paper, we present a hierarchical butterfly communication model, which is applied to an asynchronous distributed ADMM algorithm. The goal is to minimize the communication overhead of the distributed ADMM algorithm in the fully connected network. We give a theoretical analysis of the convergence of the algorithm with hierarchical butterfly communication model. Experiments show that hierarchical...
Social Networks are evolving rapidly to have a significant number of users using or joining their platforms daily, and a huge volume of information exchange and flow continuously. As human is the center of all information traffic, the information propagation became subjected to the relations and influences between the sources of these information and their followers or fans, these influences might...
The method of computer simulation of microwave devices and special laboratory workshops is described. Simulated laboratory has a module structure. The basis for constructing a model of the specific workshop is a concept of the abstract “device” with layout is identical to the installation of a real one. The software interface allows changing the configuration and frequency tags to carry out all necessary...
The purpose of the study is to analyze the accounting equation and develop a new model, based on the dual concept of monetary units and the structure of assets and claims on assets. The analysis uses the identity and characteristic functions along with a coordinate transformation, to show that the assets-claims on assets relationship involves a change in claims on assets value. The identity function...
It is well known that not all intrusions can be prevented and additional lines of defense are needed to deal with intruders. However, most current approaches use honeynets relying on the assumption that simply attracting intruders into honeypots would thwart the attack. In this paper, we propose a different and more realistic approach, which aims at delaying intrusions, so as to control the probability...
This paper presents a formal method to verify execution time bounds of programs at the source level, where timing constraints along with other functional requirements are specified in the routines' contracts and are verified in a modular manner. The approach works based on a countdown time budget mechanism to guarantee the termination of the input program, and incorporates the concepts of separation...
Regulating agencies mandate that model verification of power system components must be performed to make sure the system analysis software perform accurately. Such verification is necessary for series compensation devices used in transmission systems, since they deteriorate due to aging or prolonged subjection to stressed condition, leading to changes in compensation levels or voltage-current characteristic...
The concept of d-Separation is a key tool to analyze stochastic models defined by probability distributions of random variables that admit a factorization described by a Directed Acyclic Graph. However, in the area of dynamical systems, and especially control theory, it is common to find network models involving stochastic processes that influence each other according to a directed network where feedback...
In order to mine the abnormal learning behavior of learner in virtual learning community and carry on personalized supervision and guidance, behavior filtering model based on the factor analysis of the behavior is constructed to solve the problem of the relationship between behavior factors in the learning behavior vector space model. In view of the disadvantage of neglecting local abnormal points...
As scaling is more and more aggressive, intermittent faults are increasing their importance in current deep submicron complementary metal-oxide-semiconductor (CMOS) technologies. This work shows the dependability assessment of a fault-tolerant computer system against intermittent faults. The applied methodology lies in VHDL-based fault injection, which allows the assessment in early design phases,...
The packet rejection at destination under asynchronous transmission in high-speed optical fiber networks is examined in this study. Especially, we propose an asynchronous transmission protocol and a station network interface suitable for local area networks of passive star topology aiming to reduce the rejection probability at destination due to the receiver collisions. We assume that each station...
Recent years people have witnessed a surge of interest in APT attack, due to its complex and persistent attack characteristics. In order to prevent APT attacks, this article studies and analyzes a large number of APT attack cases which have been disclosed, gives an overview of APT attack lifecycle and attack techniques. This paper discusses the purposes of APT attacks and APT attack characteristics...
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