The Synonym management process in SAREL

The specification phase is one of the most important and least supported parts of the software development process. The SAREL system has been conceived as a knowledge-based tool to improve the specification phase. The purpose of SAREL (Assistance System for Writing Software Specifications in Natural Language) is to assist engineers in the creation of software specifications written in Natural Language (NL). These documents are divided into several parts. We can distinguish the Introduction and the Overall Description as parts that should be used in the Knowledge Base construction. The information contained in the Specific Requirements Section corresponds to the information represented in the Requirements Base. In order to obtain high-quality software requirements specification the writing norms that define the linguistic restrictions required and the software engineering constraints related to the quality factors have been taken into account. One of the controls performed is the lexical analysis that verifies the words belong to the application domain lexicon which consists of the Required and the Extended lexicon. In this sense a synonym management process is needed in order to get a quality software specification. The aim of this paper is to present the synonym management process performed during the Knowledge Base construction. Such process makes use of the Spanish Wordnet developed inside the Eurowordnet project. This process generates both the Required lexicon and the Extended lexicon that will be used during the Requirements Base construction.Postprint (published version

Arbitrary Packet Matching in OpenFlow

OpenFlow has emerged as the de facto control protocol to implement Software-Defined Networking (SDN). In its current form, the protocol specifies a set of fields on which it matches packets to perform actions, such as forwarding, discarding or modifying specific protocol header fields at a switch. The number of match fields has increased with every version of the protocol to extend matching capabilities, however, it is still not flexible enough to match on arbitrary packet fields which limits innovation and new protocol development with OpenFlow. In this paper, we argue that a fully flexible match structure is superior to continuously extending the number of fields to match upon. We use Berkeley Packet Filters (BPF) for packet classification to provide a protocol-independent, flexible alternative to today’s OpenFlow fixed match fields. We have implemented a prototype system and evaluated the performance of the proposed match scheme, with a focus on the time it takes to execute and the memory required to store different match filter specifications. Our prototype implementation demonstrates that line-rate arbitrary packet classification can be achieved with complex BPF programs

Acoustic echo and noise canceller for personal hands-free video IP phone

This paper presents implementation and evaluation of a proposed acoustic echo and noise canceller (AENC) for videotelephony-enabled personal hands-free Internet protocol (IP) phones. This canceller has the following features: noise-robust performance, low processing delay, and low computational complexity. The AENC employs an adaptive digital filter (ADF) and noise reduction (NR) methods that can effectively eliminate undesired acoustic echo and background noise included in a microphone signal even in a noisy environment. The ADF method uses the step-size control approach according to the level of disturbance such as background noise; it can minimize the effect of disturbance in a noisy environment. The NR method estimates the noise level under an assumption that the noise amplitude spectrum is constant in a short period, which cannot be applied to the amplitude spectrum of speech. In addition, this paper presents the method for decreasing the computational complexity of the ADF process without increasing the processing delay to make the processing suitable for real-time implementation. The experimental results demonstrate that the proposed AENC suppresses echo and noise sufficiently in a noisy environment; thus, resulting in natural-sounding speech