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Entwurf digitaler Schaltungen und Systeme
Theoretical Advances and Advanced Applications
Eine Einführung in die Mobilfunknetze der 5. Generation
Series: De Gruyter STEM

Abstract

The main advantage of tight frame-based time-frequency representations is to warrant a robust and stable signals reconstruction. In this paper we propose to study the speech reconstruction stability, in distortion sense, of three tight frame-based representations: the tight framelet transform, the higher density tight framelet transform and the tight framelet packet transform. The reconstruction stability is assessed using objective criteria. The results are compared with the critically wavelet packet transform. We perceive that the representations satisfying the frame theory conditions are more stable and resistant to distortions.

Abstract

The study of the human handwriting process shows that bell-shaped velocity profiles are generally observed in the handwriting motion. In this paper, a mathematical model, using input and output data for forearm muscles activities, named ElectroMyoGraphic signals (EMG), and velocities of a pen tip moving on (x, y) plan, is proposed. Using the outputs of this mathematical velocity model, we also propose a novel bi-axis control algorithm to generate handwritten graphic traces. The effectiveness of this approach should be observed on different cursive Arabic letters and geometric shapes constituting the recorded experimental basis.

Abstract

Cognitive radio (CR) is a kind of “access technology” used to co-exist among more than one radio technology without (or with minimal) interference to each other. Typically, there is one primary user of the spectrum, whereas other users are “allowed” to communicate as long as they don’t interfere the primary user. One of the well-known techniques is to sense the spectrum before initiating the communication in order to analyze the occupancy of radio frequency spectrum. In this paper, we present a comparative analysis between Energy Detection (ED) and Maximum Eigenvalue Detection (MED) spectrum sensing techniques.The performance of these two methods is evaluated in terms of their Receiver Operating Characteristics (ROC) and their detection probability for different values of Signal to Noise Ratio (SNR).

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Abstract

Nowadays, underwater vehicles (UVs) are greatly developed in almost domains. However, using this kind of vehicles for in-service oil tank inspection is not yet advanced enough. As part of an effort to design a new class of underwater vehicles suitable for inspection, the present work lays down requirements devoted to each component of those vehicles. A detailed design process is introduced and the main parts of the vehicle are described with emphasis on its related constraints. Finally prototype implementation is discussed and contributions of ROS middleware are highlighted.