Thales (Netherlands)

About: Thales (Netherlands) is a company organization based out in Hengelo, Netherlands. It is known for research contribution in the topics: Electromagnetic compatibility & Radar. The organization has 40 authors who have published 52 publications receiving 518 citations. The organization is also known as: Hollandse Signaalapparaten B.V. & Signaal.

Performance optimization aspects of common mode chokes

Abstract: Optimization aspects of common mode chokes are presented. These are based on a behavioural model for common mode chokes and its sensitivity study. Results are used to show the influence of the designable parameters on the final performance of the choke placed in a circuit.

Heat pipe array for planar cooling of rotating radar systems

Abstract: This paper presents a planar cooling strategy for rotating radar systems using heat pipe technology. The proposed design uses six 1 m long heat pipes in parallel oriented in an evaporator-down modus at an elevation angle of 85 deg. An analytical model based on conventional heat pipe limits is used to predict the performance taking into account both gravitational and centrifugal forces. The heat pipe array is mounted on a rotating platform of which both the mounting angle w.r.t. the rotational arm and rotational speed can be varied. The radial distance w.r.t. the rotational axis was set at 0.5 m. The setup was tested in an environmental chamber to simulate higher ambient temperatures as well. Moreover, measurements were conducted by varying the heat sink airflow rates. The performance was determined by the temperature gradient across the planar structure. Successful heat pipe operation and experimental performances were determined for a number of application parameters. At higher rotational speeds, the influence of centrifugal forces that may assist or hinder the working fluid circulation became discernible. For higher rotational frequencies, the mounting angle proved to be of (minor) influence on the performance in agreement with the developed model. The current design was validated for effective planar cooling of a rotating radar system for planar heat loads up to 1000 W. Temperature gradients across the planar structure remain below critical limits and overall thermal resistances from planar to ambient air conditions of 0.040 K/W and below were observed.

A value-centric model to ground norms and requirements for epartners of children

Abstract: Children as they grow up start to discover their neighborhood and surrounding areas and get increasingly involved in social interaction. We aim to support this process through a system of so-called electronic partners (ePartners) that function as teammates to their users. These ePartners should adapt their behavior to norms that govern the social contexts (e.g., the family or school) in which they are functioning. We argue that the envisaged normative framework for ePartners for children should be based on an understanding of the target domain that is grounded in user studies. It is the aim of this paper to provide such understanding, in particular answering the following questions: (1) what are the main elements that make up the social context of the target domain (family life), and how are they related?, and (2) what are the relationships between these elements of the social context and the normative framework in which we envision the ePartners to operate? To answer these questions we conducted focus groups sessions and a cultural probe study with parents and children. The transcripts from these sessions were analyzed using grounded theory, which has resulted in a grounded model that shows that (1) activities, concerns, and limitations related to family life are the main elements of the social context of this user group, and that all three elements are connected through the central concept of user values, and (2) norms can support these values by promoting activities, alleviating concerns and overcoming limitations. In this way the model provides the foundation for developing a normative framework to govern the behavior of ePartners for children, identifying user values as the starting point.

Radiated electromagnetic fields of actual devices measured in different test environments

Abstract: Correction factors between test sites are conventionally based on the antenna pattern of a tuned 1/2 /spl lambda/ dipole. Actual devices show diverse antenna patterns and correlation between results obtained at different test sites fails. This is shown in this paper using an Open Area Test Site, a Semi-Anechoic Chamber, a Full Anechoic Chamber and a Reverberating Intrinsic Reverberation Chamber for emission measurements between 20 MHz and 1 GHz. Differences between the sites of more than 40 dB can be observed.

Power tracks instead of planes to reduce radiated electromagnetic fields

Abstract: The noise voltage in the reference or ground of a printed circuit board is often the cause of unwanted radiated emission. Power supply planes attribute to the noise voltage. By replacing the power supply planes by tracks, the noise voltage in the reference or ground can be reduced, which leads to a considerable reduction of the radiated electromagnetic fields. A potential disadvantage of using power tracks is a decreased power quality, due to a higher ripple voltage. Actual circuits, fed via power planes or power tracks have been designed and measured showing the impact on radiated electromagnetic fields with constant power quality.