Learning probability spaces for classification and recognition of patterns with or without supervision

Learning probability spaces for classification and recognition of patterns with or without supervisio

On the Optimization of Mixture Resolving Signal Processing Structures

Mixture resolving signal processing optimization with optimum linear detection operators and mixture resolving estimator

Indexed induction and coinduction, fibrationally.

This paper extends the fibrational approach to induction and coinduction pioneered by Hermida and Jacobs, and developed by the current authors, in two key directions. First, we present a sound coinduction rule for any data type arising as the final coalgebra of a functor, thus relaxing Hermida and Jacobs’ restriction to polynomial data types. For this we introduce the notion of a quotient category with equality (QCE), which both abstracts the standard notion of a fibration of relations constructed from a given fibration, and plays a role in the theory of coinduction dual to that of a comprehension category with unit (CCU) in the theory of induction. Second, we show that indexed inductive and coinductive types also admit sound induction and coinduction rules. Indexed data types often arise as initial algebras and final coalgebras of functors on slice categories, so our key technical results give sufficent conditions under which we can construct, from a CCU (QCE) U : E -> B, a fibration with base B/I that models indexing by I and is also a CCU (QCE)

An 8-cm ion thruster characterization

The performance of the Ion Auxiliary Propulsion System (IAPS) thruster was increased to thrust T = 32 mN, specific impulse I sub sp = 4062 s, and thrust-to-power ratio T/P = 33 mN/kW. This performance was obtained by increasing the discharge power, accelerating voltage, propellant flow rate, and chamber magnetic field. Adding a plenum and main vaporizer for propellant distribution was the only major change required in the thruster. The modified thruster characterization is presented. A cathode magnet assembly did not improve performance. A simplified power processing unit was designed and evaluated. This unit decreased the parts count of the IAPS power processing unit by a factor of ten

A Wideband Adaptive Communication System

The concept of an open loop Adaptive Communication link is established as one which is capable of monitoring the medium through which it must perform while simultaneously transmitting information and continuously adjusting its modes of operation so as to optimize its performance with respect to a performance criterion chosen a priori. Statistical methods are applied to the adaptive communication problem. Communicating through a random multipath channel with additive noise is considered. The transmitter is specified as one which transmits one of two possible noise-like waveforms which are assumed to be known at the receiver. At any time, it is postulated that the receiver is to make its decision in accordance with the Bayes Rules which appropriately fits the amount of channel knowledge stored at the receiver. The knowledge concerning the channel state is derived a posteriori at the receiver from the information bearing signal. Consequently, as the a posteriori information changes (corresponding to changing propagation medium characteristics) the receiver’s decision circuitry also changes. Hence, the receiver is one which continuously adapts itself to yield optimum performance under the measured channel parameters. These random parameters are taken to be: channel gain, channel multipath structure, and the channel phase characteristic. Probability of error is evaluated in closed form for three different modes of operation. A major conclusion taken from these expressions is that the probability of error in no ease depends directly on the channel gain, but lather is a function of the total average energy received from all propagation modes, numerical evaluation of the error expressions enables comparisons to be made among the various systems modes of operation. These results show that measurement of the channel gain is the least important of these quantities. Given the multipath structure, the channel phase characteristic is the most important, In the optimum case a gain of about 6 db to 8 db (depending on the signal-to-noise ratio) is accomplished over the Receiver mode which performs only the multipath measurement. It is shown that the information gain concerning the multipath structure increases rapidly for a few bauds of identification time after which information build up begins to saturate. This is important because there will be available at the receiver only a finite time for which to identify this channel condition. The variance of the channel estimates are computed for maximum and minimum identification time. It is shown that the bandwidth of the transmitted waveform is the important parameter for accurate measurement of the multipath structure, while a sinusoid is sufficient for measuring the channel gain. By combining the channel measurement techniques and signal detection results, two Adaptive Receiver structures are formulated and their operation discussed. Finally, commentaries on future research are made and conclusions given about the above work

Natural history contributions of the University of Glasgow Exploration Society to Scotland and the World

Expeditions with a natural history focus have been organised by University of Glasgow staff and students since the 1930s. The educational benefits of such expeditions to students have been reported by Harper et al. ( Journal of Biological Education 51, 3- 16; 2017). Here, we present a short history of these expeditions, concentrating on their scientific achievements. In addition to expedition reports, a large number of PhD theses, masters and honours project reports and scientific papers have been based on expedition work. Many biological specimens have been deposited in museums, including some new species. We provide case histories of four expedition locations, to demonstrate the variety of work done, and the value of returning many times to the same place: Scotland, Trinidad and Tobago, North Cyprus and Ecuador. A major problem for expeditions is funding. For many years, the Carnegie Trust for the Universities of Scotland ran a funding stream that was crucial to the viability of Scottish university expeditions, but this has sadly now closed. For Glasgow University expeditions, the Blodwen Lloyd Binns Bequest has provided a reliable source since 1994, and we hope that it will continue to do so

Some Useful Coding Techniques for Binary Communication Systems

An introduction to coding theory and a discussion of specific coding techniques are given as applied to digital communication systems. The place of coding in a communication system is illustrated and the various approaches to coding are discussed. The information theory concepts required are presented along with the First and Second Fundamental Theorems of Shannon, The relation between Shannon’s theorems and coding for the noisy and noiseless channel is discussed. For the noiseless channel the techniques of Shannon, Fano, Huffman, Gilbert-More, Karp and others are discussed. For the noisy channel, the techniques of Hamming, Slepian, Elias, Cowell, Bose-Chaudhuri, Reed-Muller, Fire, and Wozencraft are presented. The relationships between the various codes are given and the advantages and disadvantages of each indicated. Numerous examples illustrating the use of the codes are given and areas of further research outlined

Correlation Receivers Minimizing Intersymbol Interference

The problem considered here is that of binary pulse communication operating in a white noise environment -wherein interfering signal pulses are generated by any of the following causes t (1) A signaling rate larger than channel bandwidths, causing pulse spill over into succeeding bands. (2) Go-channel interference or cross talk on carrier systems. (3) Signal echoes or reflections due to antenna location or mismatch of high frequency components. The optimum correlation receiver is found to be a linear combination of the desired signal pulse plus the interfering pulse. In severe cases significant improvement can be had over a correlation receiver using only the desired signal pulse. For the cause (l) above, prior receiver decisions may be used to improve the design. In particular, the immediately preceding overall receiver decision is used to select one of two parallel component correlation operations whose designs are based on a priori knowledge of the preceding transmission. It can then be shown that this is equivalent to a single correlation operation with dual decision levels, wherein the preceding receiver output controls the selection of the decision level to be utilized next. The resulting performance of this type of receiver is superior t© the correlator composed of the linear sum of signal plus interference pulses. A similar investigation was performed for the ease of Rayleigh fading on the interfering pulse. Analytical equations are established for determining the necessary solutions; however, numerical complexity precludes definitive results at this tim