1,721,006 research outputs found
A Comparison and Critique of Natural Language Understanding Tools
Full text linkIn the last 10 years, various cloud platforms enabled developers to easily create applications able to understand, with some limitations, natural languages. Nowadays, such cloud platforms for natural language understanding (NLU) are widely used, thanks to the raise of multiple chat services and conversational assistants on our mobile devices. This paper compares and analyses the main cloud-based NLU platforms, both from a descriptive and from a performance-based point of view. For the descriptive analysis, a taxonomy is proposed and six cloud platforms are analyzed. The performance evaluation, instead, compares three of these platforms, highlighting strengths and weaknesses of the different NLU tools
A Comparative Evaluation of High-Performance File Transfer Systems for Data-intensive Grid Applications
No full textThe ability of transferring very large files in the shortest amount of time is crucial for data-intensive Grid applications. Experimental evidence has shown that the mere availability of high-capacity wide-area networks is not sufficient to obtain adequate performance if vanilla TCP is used to transport data. Consequently, many alternative solutions are being explored, and a variety of data transfer tools have appeared. In this paper we experimentally compare some of these tools in various network scenarios. Our results show that solutions based on UDP adopting rate-based algorithms, result in better performance than other alternatives in most cases, while solutions based on TCP are effective only under specific circumstances
Evaluating the Impact of Urbanization on Thermal Comfort in Turin: A Numerical Simulation Study
No full textForensic analysis of the ChatSecure instant messaging application on android smartphones
Full text linkWe present the forensic analysis of the artifacts generated on Android smartphones by ChatSecure, a secure Instant Messaging application that provides strong encryption for transmitted and locally-stored data to ensure the privacy of its users.
We show that ChatSecure stores local copies of both exchanged messages and files into two distinct, AES-256 encrypted databases, and we devise a technique able to decrypt them when the secret passphrase, chosen by the user as the initial step of the encryption process, is known.
Furthermore, we show how this passphrase can be identified and extracted from the volatile memory of the device, where it persists for the entire execution of ChatSecure after having been entered by the user, thus allowing one to carry out decryption even if the passphrase is not revealed by the user.
Finally, we discuss how to analyze and correlate the data stored in the databases used by ChatSecure to identify the IM accounts used by the user and his/her buddies to communicate, as well as to reconstruct the chronology and contents of the messages and files that have been exchanged among them.
For our study we devise and use an experimental methodology, based on the use of emulated devices, that provides a very high degree of reproducibility of the results, and we validate the results it yields against those obtained from real smartphones
The Android Forensics Automator (AnForA): A tool for the Automated Forensic Analysis of Android Applications
No full textMost of our daily activities are carried out by means of mobile applications, that typically generate and store on the device large sets of data. The forensic analysis of these data thus plays a crucial role during an investigation, as it allows to reconstruct the above activities. Manually analyzing these applications is a long, tedious, and error-prone task.
In this paper we present the design, implementation, and evaluation of AnForA, a software tool that automates most of the activities that need to be carried out to forensically analyze Android applications, and that has been designed in such a way to yield various important properties, namely fidelity, artifact coverage, artifact precision, effectiveness, repeatability, and generality.
AnForA is based on a dynamic "black box" approach, in which the application to be analyzed is first installed on a virtualized Android device, and then a set of experiments are carried out, in which actions of interest are automatically performed on the application by emulating a human user that interacts with its interface. During the experiments, the file systems of the device storage are actively monitored, so that the data created or modified by each one of these actions can be located and correlated with that action.
We have devised a proof-of-concept implementation of AnForA, that we use to assess its ability in achieving its design goals, by analyzing through it several Android applications already studied in the literature, so that we can compare AnForA’s results against those reported in these papers. The results of our evaluation confirm that AnForA greatly simplifies the forensic analysis of Android applications, and exhibits all the properties mentioned above, namely fidelity, artifact coverage, artifact precision, effectiveness, repeatability, and generality, to a higher extent than previous studies published in the literature
Performance Analysis of High-Performance File Transfer Systems for Grid Applications
No full textData-intensive Grid applications require the availability of tools able to transfer very large files in the shortest amount of time. Many file-transfer tools, based on solutions aimed at overcoming the limitations imposed by the TCP protocol, have recently been developed. In this paper we experimentally compare the performance of some of these tools in various network scenarios by running experiments on PlanetLab, an open platform for the development, deployment, and access of planetary-scale services, that comprises hundreds of hosts scattered across the globe. Our results show that solutions based on UDP and adopting rate-based algorithms result in better performance than other alternatives in most cases, while solutions based on TCP achieve similar performance only under specific circumstance
Scheduling Algorithms for Multiple Bag-of-Task Applications on Desktop Grids: A Knowledge-Free Approach
No full textDesktop Grids are being increasingly used as the execution platform for a variety of applications that can be structured as Bag-of-Tasks (BoT). Scheduling BoT applications on Desktop Grids has thus attracted the attention of the scientific community, and various schedulers tailored towards them have been proposed in the literature. However, previous work has focused on scheduling a single BoT application at a time, thus neglecting other scenarios in which several users submit multiple BoT applications at the same time. This paper aims at filling this gap by proposing a set of scheduling algorithms able to deal with multiple BoT applications. The performance of these algorithm has been evaluated, by means of simulation, for a large set of operational scenarios obtained by varying both the workload submitted to the Desktop Grid and the characteristics of the involved resources. Our results show that, although there is no a clear winner among the proposed solutions, knowledge-free strategies (that is, strategies that do not require any information concerning the applications or the resources) can provide good performanc
CloudTUI-FTS: A user-friendly and powerful tool to manage Cloud Computing platforms
No full textThe NIST defines Cloud Computing as a model for en-abling ubiquitous network access to a shared pool of con-figurable computing resources. Thanks to the popularity of Cloud Computing and its various area of applicability, in the last years various projects have been realized for building Cloud systems (e.g., Amazon Web Services, Nimbus, OpenStack, Eucalyptus, and Microsoft Azure, just to name a few). Unfortunately, most of these projects (especially the open source ones) have some drawbacks: the user interfaces are not userfriendly, the basic tasks are complex to setup and to configure even for users with computer science skills. In this paper we present CloudTUI-FTS: a powerful and user-friendly tool able to easily interact with different Cloud platforms. In particular, with CloudTUI FTS the user can perform both basic tasks (e.g., start-up/shut-down a service) and advanced tasks (e.g., create policies and mechanisms to prevent faults and to provide service scalability). We evaluate the effectiveness of our tool on the CloudLab infrastructure
The ShareGrid Peer-to-Peer Desktop Grid: Infrastructure, Applications, and Performance Evaluation
No full textPeer-to-Peer (P2P) Desktop Grids are computing infrastructures that aggregate a set of desktop-class machines in which all the participating entities have the same roles, responsibilities, and rights. In this paper, we present ShareGrid, a P2P Desktop Grid infrastructure based on the OurGrid middleware, that federates the resources provided by a set of small research laboratories to easily share and use their computing resources. We discuss the techniques and tools we employed to ensure scalability, efficiency, and usability, and describe the various applications used on it. We also demonstrate the ability of ShareGrid of providing good performance and scalability by reporting the results of experimental evaluations carried out by running various applications with different resource requirements. Our experience with ShareGrid indicates that P2P Desktop Grids can represent an effective answer to the computing needs of small research laboratories, as long as they provide both ease of management and use, and good scalability and performance
CloudTUI: a multi cloud platform text user interface
No full textMost of the online services that we use everyday are provided by Cloud Computing infrastructures. This widespread is due to the substantial effort spent to make all these services as much user-friendly as possible. Unfortunately, the usage of the most popular Cloud Computing infrastructures is not easy at all and it requires high computer science skills. In this paper, we propose CloudTUI: a multi Cloud Computing platform text-based interface able to make the interaction with Cloud systems easy and intuitive even for users without any prior experience concerning the Cloud Computing paradigm
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