In this paper we show how formal computer science concepts—such as encoding, algorithm or computability—can be interpreted philosophically, including ontologically and epistemologically. Such interpretations lead to questions and problems, the working solutions of which constitute some form of pre-philosophical worldview. In this work we focus on questions inspired by the IT distinction between digitality and analogicity, which has its mathematical origin in the mathematical distinction between discreteness and continuity. These include the following questions: 1) Is the deep structure of physical reality digital or analog, 2) does the human mind resemble a more digital or analog computational system, 3) does the answer to the second question give us a cognitively fruitful insight into the cognitive limitations of the mind? As a particularly important basis for the above questions, we consider the fact that the computational power (i.e., the range of solvable problems) of some types of analog computations is greater than that of digital computations.
This paper addresses the issue of the development of FOR DREAD THAT – a negative purpose subordinator in the history of the English language. The theoretical foundation of this work are the mechanisms of grammaticalisation suggested by Heine and Kuteva in many works of theirs. The gathered material shows that the development of this relatively rarely used subordinator constitutes a case of a typical grammaticalisation whose rise might have been the result of analogy with FOR FEAR THAT.
Analog circuits need more effective fault diagnosis methods. In this study, the fault diagnosis method of analog circuits was studied. The fault feature vectors were extracted by a wavelet transform and then classified by a generalized regression neural network (GRNN). In order to improve the classification performance, a wolf pack algorithm (WPA) was used to optimize the GRNN, and a WPA-GRNN diagnosis algorithm was obtained. Then a simulation experiment was carried out taking a Sallen–Key bandpass filter as an example. It was found from the experimental results that the WPA could achieve the preset accuracy in the eighth iteration and had a good optimization effect. In the comparison between the GRNN, genetic algorithm (GA)-GRNN and WPA-GRNN, the WPA-GRNN had the highest diagnostic accuracy, and moreover it had high accuracy in diagnosing a single fault than multiple faults, short training time, smaller error, and an average accuracy rate of 91%. The experimental results prove the effectiveness of the WPA-GRNN in fault diagnosis of analog circuits, which can make some contributions to the further development of the fault diagnosis of analog circuits.
The method described in this work allows to determine the optimal distribution of pulses of digital signal as well as the non-linear mathematical model based on a multiple regression statistical analysis, which are specialized to an effective and low-cost testing of functional parameters in analog electronic circuits. The aim of this concept is to simplify the process of analog circuit specification validation and minimize hardware implementation, time and memory requirements during the testing stage. This strategy requires simulations of the analyzed analog electronic circuit; however, this effort is done only once – before the testing stage. Then, validation of circuit specification can be obtained after a quick, very low-cost procedure without time consuming computations and without expensive external measuring equipment usage. The analyzed test signature is a time response of the analog circuit to the stream of digital pulses for which distributions were determined during evolutionary optimization cycles. Besides, evolutionary computations assure determination of the optimal form and size of the non-linear mathematical formula used to estimate specific functional parameters. Generally, the obtained mathematical model has a structure similar to the polynomial one with terms calculated by means of multiple regression procedure. However, a higher ordered polynomial usage makes it possible to reach non-linear estimation model that improves accuracy of circuit parametric identification. It should be noted that all the evolutionary calculations are made only at the before test stage and the main computational effort, for the analog circuit specification test design, is necessary only once. Such diagnosing system is fully synchronized by a global digital signal clock that precisely determines time points of the slopes of input excitation pulses as well as acquired output signature samples. Efficiency of the proposed technique is confirmed by results obtained for examples based on analog circuits used in previous (and other) publications as test benchmarks.
The present work involved an extensive outdoor performance testing program of a solar water heating system that consists of four evacuated tube solar collectors incorporating four wickless heat pipes integrated to a storage tank. Tests were conducted under the weather conditions of Baghdad, Iraq. The heat pipes were of 22 mm diameter, 1800 mm evaporator length and 200 mm condenser length. Three heat pipe working fluids were employed, ethanol, methanol, and acetone at an inventory of 50% by volume of the heat pipe evaporator sections. The system was tested outdoors with various load conditions. Results showed that the system performance was not sensitive to the type of heat pipe working fluid employed here. Improved overall efficiency of the solar system was obtained with hot water withdrawal (load conditions) by 14%. A theoretical analysis was formulated for the solar system performance using an energy balance based iterative electrical analogy formulation to compare the experimental temperature behavior and energy output with theoretical predictions. Good agreement of 8% was obtained between theoretical and experimental values.
This paper presents exemplary exercise on the fundamentals of signal processing course which is offered for second year bachelor level students. Application of Field Programmable Analog Array (FPAA) for pulse amplitude modulation (PAM) exercise is described with signal processing laboratory. There are presented two methods for implementing PAM modulation and demodulation technique in FPAA module. Example configuration files are available form Authors’ web site.
A hybrid artificial boundary condition (HABC) that combines the volume-based acoustic damping layer (ADL) and the local face-based characteristic boundary condition (CBC) is presented to enhance the absorption of acoustic waves near the computational boundaries. This method is applied to the prediction of aerodynamic noise from a circular cylinder immersed in uniform compressible viscous flow. Different ADLs are designed to assess their effectiveness whereby the effect of the mesh-stretch direction on wave absorption in the ADL is analysed. Large eddy simulation (LES) and FW-H acoustic analogy method are implemented to predict the far-field noise, and the sensitivities of each approach to the HABC are compared. In the LES computed propagation field of the fluctuation pressure and the frequency-domain results, the spurious reflections at edges are found to be significantly eliminated by the HABC through the effective dissipation of incident waves along the wave-front direction in the ADL. Thereby, the LES results are found to be in a good agreement with the acoustic pressure predicted using FW-H method, which is observed to be just affected slightly by reflected waves.
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