Philips Journal of Research最新文献

Various intrinsic and extrinsic parameters that play a role in the preparation of materials for direct bonding are discussed in this paper. The constitution of a material or a wafer can be described on the basis of its shape and its mechanical, chemical and physical surface finish. Subsurface damage is also of importance with respect to direct bonding applications. Different polishing strategies have been evaluated for polishing the surfaces of different materials to a finish suitable for direct bonding. Optical elements can be polished by means of mechanical polishing; refractory metals by means of dedicated mechanical polishing; III–V compounds by means of chemical polishing; semiconductors by means of tribochemical, i.e. chemomechanical polishing; hard materials by means of enhanced tribochemical polishing; noble metals by means of organo-liquid-supported tribochemical polishing; non-noble metals by means of oxidation-stimulated polishing. After such preparative treatments the material or wafer has to be cleaned, using a suitable method. Certain aspects of the bonding phenomenon itself will also be discussed in this paper.

The paper describes a system that produces spoken monologues derived from information in a database. The sentences of these monologues are generated from templates of syntactic structures, which may contain open slots in which other elements, usually noun phrases, can be inserted. It is shown how these sentences string together to form a coherent message. This message has to be pronounced correctly, which means, among other things, that it has to be prosodically acceptable. The paper indicates how linguistic information is used to arrive at an acceptable prosodic structure, which, in turn, feeds into a module which takes care of the phonetic realization of the monologue.

This paper describes recording experiments on magneto-optical media using nanosecond laser pulses for writing data. By reducing the length of the write pulses the effects of thermal diffusion are diminished. It is further shown that user bit lengths of 0.8 μm under pulse length modulation coding can be achieved without having to resort to a special write strategy. Some other beneficial effects of this method are pointed out for media as well as for laser requirements. Tests with commercially available laser diodes give insight into the possibilities of implementing short pulsed lasers in applications.

Recognition accuracy has been the primary objective of most speech recognition research, and impressive results have been obtained, e.g. less than 0.3% word error rate on a speaker-independent digit recognition task. When it comes to real-world applications, robustness and real-time response might be more important issues. For the first requirement we review some of the work on robustness and discuss one specific technique, spectral normalization, in more detail. The requirement of real-time response has to be considered in the light of the limited hardware resources in voice control applications, which are due to the tight cost constraints. In this paper we discuss in detail one specific means to reduce the processing and memory demands: a clustering technique applied at various levels within the acoustic modelling.

Today speech recognition of a small vocabulary can be realized so cost-effectively that the technology can penetrate into consumer electronics. But, as first applications that failed on the market show, it is by no means obvious how to incorporate voice control in a user interface. This paper addresses the issue of how to design a voice control so that the user perceives it as a benefit. User interface guidelines that are adapted or specific to voice control are presented. Then the process of designing a voice control in the user-centred approach is described. By means of two examples, the car stereo and telephone answering machine, it is shown how this is turned into practice.

Direct bonding of organic polymeric materials can be realized when their surfaces are prepared in such a way that they are clean, smooth and susceptible to direct-bonding. In the surface-preparation process, tribo-chemical polishing is an essential step. Polymeric materials such as polymethylmethacrylate (PMMA), polyarylate, polyimide and polycarbonate were bonded either to themselves, to another polymer or to an inorganic material such as silicon or fused silica. The surfacial bond energy of the room temperature bond is surprisingly high: 0.1–0.2 J/m². Heating strengthens the direct bond; for example, for a bonded PMMA/PMMA wafer pair annealed at the glass-transition temperature of PMMA (105°C), the surfacial bond strength increases to 7.8 J/m². This indicates that the bonded surfaces are fused and are interlinked by chemical bonds. When polymers are bonded to low-thermal-expansion materials such as Si and fused silica, during annealing treatments, thermal stresses can induce fracturing of the inorganic part of the bonded wafer pair. By limiting the maximum annealing temperature or the size of the bonded area, fracturing can be avoided.

An introductory review of some basic speech coding techniques covers the most important properties of speech production and hearing, the ubiquitous techniques of quantization and linear prediction, and a recital of the most important measures of coding performance. In the survey that follows, several standardized speech coding systems reflecting the state of the art in speech coding are discussed in terms of coding method, bit rate, performance, complexity and typical application areas. Major future trends are indicated on the basis of expected future standards. The paper, which primarily deals with narrowband speech coding systems, is concluded by a review of the state of affairs and an outline of the future trends in the area of wideband speech coding.