fractional delay filter is a device for bandlimited interpolation between samples. It finds applications in numerous fields of signal processing, including communications, array processing, speech processing, and music technology. In this article, we present a comprehensive review of FIR and allpass filter design techniques for bandlimited approximation of a fractional digital delay. Emphasis is on simple and efficient methods that are well suited for fast coefficient update or continuous control of the delay value. Various new approaches are proposed and several examples are provided to illustrate the performance of the methods. We also discuss the implementation complexity of the algorithms. We focus on four applications where fractional delay filers are needed: synchronization of digital modems, incommensurate sampling rate conversion, high-resolution pitch prediction, and sound synthesis of musical instruments. 30 IEEE SIGNAL PROCESSING MAGAZINE

No abstract

In numerous applications, such as communications, audio and music technology, speech coding and synthesis, antenna and transducer arrays, and time delay estimation, not only the sampling frequency but the actual sampling instants are of crucial importance. Digital fractional delay (FD) filters provide a useful building block that can be used for fine-tuning the sampling instants, i.e., implement the required bandlimited interpolation. In this paper an overview of design techniques and applications is given.

A numerical model that simulates ice accretion amounts and ice shapes on wind turbine blades is presented. The model simulates both rime icing due to fog droplets and glaze icing due to precipitation at all angles of droplet attack experienced by wind turbine blades. Icing can be simulated by the model also when the blade is heated. The sensitivity of ice accretions to meteorological variables is studied and predictions of the model are compared to data from icing wind tunnel experiments and from a field study of natural wind turbine icing. Applications of the model in the design of blade heating elements for anti-icing of wind turbines are described.

No abstract

Abstract-The use of the delta operator in the realizations of digital filters has recently gained interest due to its good finite-word-length performance under fast sampling. We studied efficient direct form structures, and show that only some of them can be used in delta configurations, while others are evidently unstable. In this paper, we focus on the roundoff noise analysis. Of all the direct-form structures, the direct form II transposed (DFIIt) delta structure has the lowest quantization noise level at its output. This structure outperforms both the conventional direct-form (delay) structures, as well as the state-space structures for narrow-band low-pass filters with respect to output roundoff noise. Excellent roundoff noise performance is achieved at the cost of only a minor additional implementation complexity when compared with the corresponding delay realization. Complexity of a signal processor implementation of the DFIIt delta structure, which was found to be the most suitable delta structure for signal processors, is compared with those of the direct form and state-space delay structures. In addition, some hardware implementation aspects are discussed, including the minimization of the internal word length.Index Terms-Delta operator, direct-form structures, roundoff noise.

The aim of the study was to investigate the relationships between situational and contextual self-determined motivation and physical activity intensity as measured by heart rates during a ninth-grade students' physical education (PE) class. The participants of the study were 139 Finnish ninth-grade students (15-year-olds). The data were collected during one 60-minute PE class held by the class PE teacher. Results revealed that more self-determined situational motivation negatively predicted the lowest heart rate category (<120 beats/min.) as well as the next lowest heart rate category (120-40 beats/min.). Neither variation in type of situational or contextual motivations explained heart rates in the next highest category (140-60 beats/min.), whereas the highest heart rate category (>160 beats/min.) was positively predicted by situational motivation. Lastly, highly self-determined situational motivation accounted for a significant amount of variance in mean heart rate value. Taken together, results revealed that situational motivation associated more strongly with physical activity intensity as measured by heart rate than did contextual motivation.

No abstract