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.

Wireless communication system for reliable communication between a group of apparatuses

Abstract: The communication system allows a group of apparatuses, such as game computers and Personal Digital Assistants, to communicate wirelessly. A period following transmission of a message frame (500) is reserved for acknowledging reception. Receiving apparatuses (101, e.a.) wait a random time before acknowledging. Only the first apparatus (101) to time-out transmits an acknowledgment frame (510). An apparatus (100, e.a.) comprises detection means (400) for detecting a frame transmission, which is followed by first timing means (310) setting a first timer at a first time. Message sending means (200) transmits a message frame (500) when the first timer is expired. Following reception of the message frame (500) by message receiving means (210), second timing (320) means sets a second timer at a random time, which is smaller than the first time. Acknowledge sending means (220) transmits an acknowledgment frame (510) if the second timer expires prior to detecting another transmission.

Design of a radiative surface coil array element at 7 T: the single-side adapted dipole antenna.

Abstract: Ultra high field MR imaging (≥7 T) of deeply located targets in the body is facing some radiofrequency-field related challenges: interference patterns, reduced penetration depth, and higher Specific Absorbtion Ratio (SAR) levels. These can be alleviated by redesigning the elements of the transmit or transceive array. This is because at these high excitation field (B1) frequencies, conventional array element designs may have become suboptimal. In this work, an alternative design approach is presented, regarding coil array elements as antennas. Following this approach, the Poynting vector of the element should be oriented towards the imaging target region. The single-side adapted dipole antenna is a novel design that fulfills this requirement. The performance of this design as a transmit coil array element has been characterized by comparison with three other, more conventional designs using finite difference time domain (FDTD) simulations and B measurements on a phantom. Results show that the B level at the deeper regions is higher while maintaining relatively low SAR levels. Also, the B field distribution is more symmetrical and more uniform, promising better image homogeneity. Eight radiative antennas have been combined into a belt-like surface array for prostate imaging. T1-weighted (T1W) and T2-weighted (T2W) volunteer images are presented along with B measurements to demonstrate the improved efficiency. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.