Philips

About: Philips is a company organization based out in Vantaa, Finland. It is known for research contribution in the topics: Signal & Layer (electronics). The organization has 68260 authors who have published 99663 publications receiving 1882329 citations. The organization is also known as: Koninklijke Philips Electronics N.V. & Royal Philips Electronics.

Circuit for measuring the capacity of a battery

Abstract: The discharge capacity of a secondary battery, e.g. a Ni-Cd battery, has a maximum value at room temperature and gradually decreases both with an increase and decrease of ambient temperature. The battery discharge capacity also varies inversely with the number of battery charge/discharge cycles of the battery. A circuit for measuring the remaining discharge capacity of the secondary battery comprises a capacitor (23) whose temperature and age-variation characteristics are very similar to those of the discharge capacity of the secondary battery. The current flowing through the battery and motor (13) is detected by a series resistor (17). A voltage follower (20) responds to the detected voltage and drives a resistor (24), so that capacitor (23) is discharged at a rate determined by the resistor (24) current. The capacitor voltage is compared with a predetermined value by a hysteresis comparator (29) which controls the ON/OFF state of a transistor (21) in accordance with the comparison. The comparator output pulses, i.e., the capacitor charge/discharge cycles, are counted by a counter (31). Since the capacitance variation of the capacitor corresponds to the variation in battery discharge capacity with ambient temperature and also with the time of use, the counter (31) indicates very accurately the remaining battery capacity

DQE(f) of four generations of computed radiography acquisition devices

Abstract: Measurements were made of the MTF(f), NPS(f), and DQE(f) of four generations of computed radiography(CR) imaging plates and three generations of CR image readers. The MTF generally showed only a minor change between generations of plates and readers, but the DQE(f) has improved substantially from a very early plate/reader combination to a more recent one. The DQE in the more recent plate/reader combination is 1.3× greater at low frequencies and about 3× greater at high frequencies than the much earlier versions. Thus there has been substantial improvement in the imaging performance obtainable with CR since some of the early observer studies which indicated poorer performance with CR than with screen–film.

Presence and risks of nanosilica in food products

Abstract: This study uniquely describes all steps of the risk assessment process for the use of one specific nanomaterial (nanosilica) in food products. The aim was to identify gaps in essential knowledge and the difficulties and uncertainties associated with each of these steps. Several food products with added silica (E551) were analyzed for the presence, particle size and concentration of nanosilica particles, using experimental analytical data, and the intake of nanosilica via food was estimated. As no information is available on the absorption of nanosilica from the gastrointestinal tract, two scenarios for risk assessment were considered. The first scenario assumes that the silica is absorbed as dissolved silica, while the second scenario assumes that nanosilica particles themselves are absorbed from the gastrointestinal tract. For the first scenario no adverse effects are expected to occur. For the second scenario there are too many uncertainties to allow proper risk assessment. Therefore, it is recommended to prioritize research on how nanosilica is absorbed from the gastrointestinal tract.

Power driver topologies and control schemes for LEDs

Abstract: This paper deals with power electronic drivers for LED strings. Due to the enormous progress recently achieved in the technology of light emitting diodes (LEDs) it can be expected that LEDs lighting will replace incandescent and halogen bulbs in general illumination in the near future. A LED light source typically consists of a series connection of single LED cells. It shows a similar behaviour like a zener diode. For efficiency reasons LED strings can not be supplied via series resistors but need switched mode power drivers with current control. Different standard DC-DC converter topologies are discussed which can be adapted to feed a constant current into a LED load. For future LED driver developments it has to be considered that LEDs can also efficiently be supplied by pulsating currents. This simplifies the converter and control design and reduces the number of components. Hence, different converter topologies are studied which are able to stabilise the average value of a pulsating output current. This also includes topologies with galvanic isolation. Resonant operating LED drivers seem to be specially suited for this task. Hence, a series resonant galvanic isolating LED driver is studied in detail. Under certain conditions this converter does not need a current sensor to stabilise the average current in the LED load. Finally, the features of different pulsating current waves are investigated concerning their peak, RMS and high frequency content.

Linear discriminant analysis for improved large vocabulary continuous speech recognition

Abstract: The interaction of linear discriminant analysis (LDA) and a modeling approach using continuous Laplacian mixture density HMM is studied experimentally. The largest improvements in speech recognition could be obtained when the classes for the LDA transform were defined to be sub-phone units. On a 12000 word German recognition task with small overlap between training and test vocabulary a reduction in error rate by one-fifth was achieved compared to the case without LDA. On the development set of the DARPA RM1 task the error rate was reduced by one-third. For the DARPA speaker-dependent no-grammar case, the error rate averaged over 12 speakers was 9.9%. This was achieved with a recognizer using LDA and a set of only 47 Viterbi-trained context-independent phonemes. >