A fast battery charging algorithm for an intelligent PV system with capability of on-line temperature compensation

This study presents a battery fast-charging mechanism for an intelligent generic photovoltaic (PV) system and also a pulse-charging method for the on-line temperature compensation. The fuzzy logic control (FLC) is adopted for fast maximum power point tracking (MPPT) of the PV system. Along with proposed battery charging algorithms, the controller presented in this study is named a fuzzy battery-managing controller (FBMC). The fast battery charging by this controller does not only prolong battery lifetime by restoring the maximum battery state of charge (SOC) in the shortest time but also with the temperature compensation. The designed charging algorithm consists of three different stages, namely constant current (CC), pulse charging and trickle charging. In the CC mode, the current at maximum power of the PV array is used for fast charging. The pulse charging mode is next adopted to contain temperature rise while maintaining relatively fast charging speed. To prevent battery damage by charging as battery capacity is close to its full status, 100 % SOC, the float charging mode is finally activated by further decreasing charging currents. Simulations are conducted via Powersim to validate the FBMC performance and the PV system model. The FBMC is next implemented by a DSP module (TMS320F2812) in order to adjust the switching duty cycle during operations of the buck converter. Finally, experimental results were compared with a general constant current and/or voltage method. The results show favorable performance of the propose charging method.     

Reading and skimming from computer screens and books: the paperless office revisited?

Past research has demonstrated that reading efficiency is lower from the standard computer displays of the 1980s than from paper. In the present experiments, subjects read or skimmed stories, sometimes from a high-quality CRT (cathode ray tube) and sometimes from a book. Skimming was 41% slower from the CRTs than from the book. Possible reasons for this finding are discussed. Reading speed and comprehension were equivalent for the high-quality CRTs and the book. The paperless office may be imminent after all.     

The use of a uniquely encoded light pattern for range data acquisition

Building a three-dimensional vision system requires three-dimensional scene information in the form of range data. Using a structured light system accompanied by the triangulation method is a typical approach to obtain such data. In this paper, we present a ranging method using an encoded grid light pattern. Our method is different from the previous approaches in such a way that the codes are unique for any grid intersection points and maximal for a given set of code primitives. An efficient data acquisition procedure is obtained by applying the uniqueness of a code. The encoding scheme for the light pattern and the decoding scheme for the imaged illuminated pattern are presented. We also discuss a fault-tolerant approach which makes the ranging system robust.     

Parallel path consistency

Filtering algorithms are well accepted as a means of speeding up the solution of the consistent labeling problem (CLP). Despite the fact that path consistency does a better job of filtering than arc consistency, AC is still the preferred technique because it has a much lower time complexity. We are implementing parallel path consistency algorithms on multiprocessors and comparing their performance to the best sequential and parallel arc consistency algorithms.^(1,2) (See also work by Kerethoet al. ⁽³⁾ and Kasif⁽⁴⁾) Preliminary work has shown linear performance increases for parallelized path consistency and also shown that in many cases performance is significantly better than the theoretical worst case. These two results lead us to believe that parallel path consistency may be a superior filtering technique. Finally, we have implemented path consistency as an outer product computation and have obtained good results (e.g., linear speedup on a 64K-node Connection Machine 2).     

Trial and Error

A pac-learning algorithm is -space bounded, if it stores at most examples from the sample at any time. We characterize the -space learnable concept classes. For this purpose we introduce the compression parameter of a concept class and design our Trial and Error Learning Algorithm. We show : is -space learnable if and only if the compression parameter of is at most . This learning algorithm does not produce a hypothesis consistent with the whole sample as previous approaches e.g. by Floyd, who presents consistent space bounded learning algorithms, but has to restrict herself to very special concept classes. On the other hand our algorithm needs large samples; the compression parameter appears as exponent in the sample size. We present several examples of polynomial time space bounded learnable concept classes: – all intersection closed concept classes with finite VC–dimension. – convex -gons in . – halfspaces in . – unions of triangles in . We further relate the compression parameter to the VC–dimension, and discuss variants of this parameter. Received May 24, 1994 / July 4, 1995     

Nighttime legibility of traffic signs: conditions eliminating the effects of driver age and disability glare

The effects of observer age and environmental glare on nighttime legibility of traffic signs were investigated in two field experiments with the subjects driving or riding in a car towards a sign. Experiment 1 showed that equating older and younger subjects in terms of their low luminance/high contrast visual acuity resulted in elimination of any age effects on legibility. Furthermore, the presence of a glare source with an illuminance of 0.17 or 0.017 lux offset 2° from the sign legend improved legibility distance significantly. The results of Experiment 2 indicated that a glare source with an illuminance of 0.0098 lux had no effect on legibility when presented at an offset angle of 1.5° or 0.6°, but it had a significant detrimental effect at an offset angle of 0.2°. The present findings suggest that (1) the usually observed age-related performance decrement on nighttime legibility tasks is the result of visual-acuity deficits, and not shortcomings in information-processing ability; (2) legibility is relatively unaffected by glare, unless the glare angle is very small or glare level very high; and (3) glare sources positioned outside of the fovea might improve nighttime legibility performance under certain conditions.     

Structure,superconductivity and magnetism of new rare earth-rhodium silicides RE2Rh3Si5 of U2Co3Si5-type

New ternary silicides RE₂Rh₃Si₅ (RE = Y, La, Nd, Sm, Gd, Tb, Dy, Ho, Er) have been prepared. They crystalize in the U₂Co₃Si₅-type structure. Only the silicides containing the diamagnetic rare earths Y and La show a superconducting transition at T_Cr = 4.4 ± 0.2K and T_Cr = 2.7 ± 0.1K respectively, those with magnetic rare earths order antiferromagnetically at low temperature.     

Interactions magnetiques intra- et interclusters dans les pentafluorures RuF5 et OsF5

The nature of the magnetic interactions in RuF₅ and OsF₅ has been investigated using neutron diffraction and magnetic measurements under high applied fields. RuF₅ and OsF₅ are magnetically ordered at respectively T_N = 5 and 6 K. The magnetic structures have been determined. A model based on isolated tetranuclear clusters M₄F₂₀ (M = Ru or Os) has been applied to explain the magnetic behavior above the Néel temperature. The intracluster exchange interactions are antiferromagnetic. The fitting of the magnetization data leads to an exchange constant of $\text{J}\text{k}\text{= ?7.7}\text{K}$ for RuF₅, in good agreement with that calculated from the thermal variation of the magnetic susceptibility.     

Mössbauer resonance studies on the Ca2Fe2O5-LaFeO3 system

Phases between Ca₂Fe₂O₅ and LaFeO₃ with La_1?2yCa_2yFe³⁺O_3?y formulation have been prepared in order to study the oxygen defects in perovskite-related ferrites. X-ray-diffraction analysis and magnetic measurements have confirmed the previous results i.e. the existence of a critical concentration of vacancies above which long range ordering appears. A detailed Mössbauer resonance study shows a continuous evolution of the iron environment, tetrahedra being formed even for low values of y. This result has been discussed and compared with previous ones for homologous CaTi_1?2yFe_2yO_?y phases.     

A fast two-dimensional line clipping algorithm via line encoding

Clipping of lines is an important operation in most graphics applications. Two main types of line clipping algorithms have been proposed, namely the encoding approach (with the Cohen-Sutherland algorithm as a representative) and the parametric approach (with the Liang-Barsky and the Cyrus-Beck algorithms as representatives.) The technique described in this paper is a new encoding approach. Unlike the Cohen-Sutherland algorithm, which encodes the end points of a line, the line is encoded. Based on the line code, appropriate clipping actions are performed. Experimental results demonstrate that the proposed algorithm outperforms the Cohen-Sutherland, the Liang-Barsky and the Cyrus-Beck algorithms.