Speech Recognition Principles And Applications Essays - Linguistics

Speech Recognition: Principles And Applications Table of contents Abstract 3 Overview of the Characteristics of Automatic Speech Recognition Systems 4 Number of Words 4 Use of Grammar 5 Continuous vs. Discrete Speech 5 Speaker Dependency 6 Early Approaches to Automatic Speech Recognition 6 Acoustic-Phonetic Approach 7 Statistical Pattern Recognition Approach 8 Modern Approach to Automatic Speech Recognition 8 Hidden Markov Models 9 Training of an Automatic Speech Recognition System Based on HMMs 11 Sub-Word Units 11 Applications of Automatic Speech Recognition Systems 12 Automated Call-Type Recognition 13 Data Entry 13 Future Applications Using Automatic Speech Recognition Systems 14 Conclusion 14 References 15 Abstract With the advances of technology, a lot of people may think that integrating the ability of understanding human speech in a computer system is a piece of cake. However, scientists disagree. Since the early nineteen fifties, scientists have tried to implement the perfect automatic speech recognition system, but they failed. They were successful in making the computer recognise a large number of words, but till now, a computer that understands everything without meeting any conditions does not exist. Due to the enormous applications, a lot of money and time is spent in improving speech recognition systems. SPEECH RECOGNITION: PRINCIPLES AND APPLICATIONS Nowadays, computer systems play a major role in our lives. They are used everywhere beginning with homes, offices, restaurants, gas stations, and so on. Nonetheless, for some, computers still represent the machine they will never know how to use. Communicating with a computer is done using a keyboard or a mouse, devices many people are not comfortable using. Speech recognition solves this problem and destroys the boundaries between humans and computers. Using a computer will be as easy as talking with your friend. Unfortunately, scientists have discovered that implementing a perfect speech recognition system is no easy task. This report will present the principles and the major approaches to speech recognition systems along with some of their applications. Overview of the Characteristics of Automatic Speech Recognition Systems How can we evaluate a speech recognition system? Obviously describing it by good or bad isnt enough since the performance of such a system may be outstanding in one application and poor in another. In fact, speech recognition systems are designed according to the application. Some of these variable characteristics are presented below. Number of Words The major characteristic of a speech recognition system is the number of words it can recognise. The question that comes to mind is how many words are enough so that the performance of a speech recognition system is acceptable. The answer depends on the application (6, p98). Some applications may require few words, like automated call-type recognition, others may require thousands, like data entry. However, increasing the number of words or the vocabulary of a speech recognition system increases its complexity and decreases its performance (probability of error is higher)(6, p.98). Systems with large vocabularies are also slower since more time is needed to search a word in a large vocabulary. Increasing the number of words isnt enough because the speech recognition system is unable to differentiate words like to and two or right and write (6 ,p.98). Use of Grammar Using grammar, differentiating words like to and two or right and write is possible. Grammar is also used to speed up a speech recognition system by narrowing the range of the search (6,p.98). Grammar also increases the performance of a speech recognition system by eliminating inappropriate word sequencing. However, grammar doesnt allow random dictation which is a problem for some applications (6, p.98). Continuous vs. Discrete Speech When speaking to each other, we dont pause between words. In other words, we use continuous speech. However, for speech recognition systems, there is difficulty in dealing with continuous speech (6, p.98). The easy way out will be using discrete speech where we pause between words (6, p.100). With discrete speech input, the silent gap between words is used to determine the boundary of the word, whereas in continuous speech, the speech recognition system must separate words using an algorithm which is not a hundred per cent accurate. Still, for a small vocabulary and using grammar, continuous speech recognition systems are available. They are reliable and do not require great computational power (6, p.100). However, for large vocabulary, continuous speech recognition systems are very difficult to achieve, require

Composite Materials in Aerospace

Composite Materials in Aerospace Weight is everything when it comes to heavier-than-air machines, and designers have striven continuously to improve lift to weight ratios since man first took to the air. Composite materials have played a major part in weight reduction, and today there are three main types in use: carbon fiber-, glass-, and aramid- reinforced epoxy.; there are others, such as boron-reinforced (itself a composite formed on a tungsten core). Since 1987, the use of composites in aerospace has doubled every five years, and new composites regularly appear. Uses Composites are versatile, used for both structural applications and components, in all aircraft and spacecraft, from hot air balloon gondolas and gliders to passenger airliners, fighter planes, and the Space Shuttle. Applications range from complete airplanes such as the Beech Starship to wing assemblies, helicopter rotor blades, propellers, seats, and instrument enclosures. The types have different mechanical properties and are used in different areas of aircraft construction. Carbon fiber, for example, has unique fatigue  behavior  and is brittle, as Rolls-Royce discovered in the 1960s when the innovative RB211 jet engine with carbon fiber compressor blades failed catastrophically due to bird strikes. Whereas an aluminum wing has a known metal fatigue lifetime, carbon fiber is much less predictable (but dramatically improving every day), but boron works well (such as in the wing of the Advanced Tactical Fighter). Aramid fibers (Kevlar is a well-known proprietary brand owned by DuPont) are widely used in honeycomb sheet form to construct very stiff, very light bulkhead, fuel tanks, and floors. They are also used in leading- and trailing-edge wing components. In an experimental program, Boeing successfully used 1,500 composite parts to replace 11,000 metal components in a helicopter. The use of composite-based components in place of metal as part of maintenance cycles is growing rapidly in commercial and leisure aviation. Overall, carbon fiber is the most widely used composite fiber in aerospace applications. Advantages We have already touched on a few, such as weight saving, but here is a full list: Weight reduction - savings in the range of 20%-50% are often quoted.It is easy to assemble complex components using automated layup machinery and rotational molding processes.Monocoque (single-shell) molded structures deliver higher strength at a much lower weight.Mechanical properties can be tailored by lay-up design, with tapering thicknesses of reinforcing cloth and cloth orientation.Thermal stability of composites means they dont expand/contract excessively with a change in temperature (for example a 90 °F runway to -67 °F at 35,000 feet in a matter of minutes).High impact resistance - Kevlar (aramid) armor shields planes, too - for example, reducing accidental damage to the engine pylons which carry engine controls and fuel lines.High damage tolerance improves accident survivability.Galvanic - electrical - corrosion problems which would occur when two dissimilar metals are in contact (particularly in humid marine environments) are avoided. (Here non-conductive fiberglass pla ys a role.) Combination fatigue/corrosion problems are virtually eliminated. Future Outlook With ever-increasing fuel costs and environmental lobbying, commercial flying is under sustained pressure to improve performance, and weight reduction is a key factor in the equation. Beyond the day-to-day operating costs, the aircraft maintenance programs can be simplified by component count reduction and corrosion reduction. The competitive nature of the aircraft construction business ensures that any opportunity to reduce operating costs is explored and exploited wherever possible. Competition exists in the military too, with continuous pressure to increase payload and range, flight performance characteristics, and survivability, not only of airplanes but of missiles, too. Composite technology continues to advance, and the advent of new types such as basalt and carbon nanotube forms is certain to accelerate and extend composite usage. When it comes to aerospace, composite materials are here to stay.

To What Extent Does a Company Exist Only For The Benefit Of Its Essay

To What Extent Does a Company Exist Only For The Benefit Of Its Shareholders - Essay Example This research will begin with the statement that the Occupy protests taking place around the world have highlighted a problem that lies at the heart of corporate structures: the single-minded pursuit of profit at the expense of everything else. Indeed, the logic of the market demands that players in it pursue maximum gain. A company, therefore, is expected to pursue maximum profits for its shareholders. Wealth generation becomes a single and overarching focus.   Experience has shown us however that this has sometimes led to unfortunate consequences. The single-mindedness with which profit is pursued has allowed companies to neglect other issues and concerns. It became of little surprise therefore that the recession that has hit much of Europe and America and the widely-reported corporate scandals have highlighted the need to make corporate governance at the top of a company’s order of priorities and the overriding principle guiding its directors. The escalating protests on W all Street in the United States, for example, demonstrate growing public outrage against corporate greed and white-collared crimes.   In simple terms, this paper suggests that the company must exist only for the benefit of its shareholders only to the extent that it does not encourage corporate deviance and it retains its obligations to the rest of the society, not necessarily only its shareholders. This paper will begin by first discussing the Agency theory and its implications. Next, it will discuss the theory counterpoised to that, which is the Stakeholder theory – highlighting corners and turns of the debate that theoretically underpins the question as to whether and to what extent a company should exist only for the benefit of the shareholders.