Fabrication and characterization of a planar interleaved micro-transformer with magnetic core

This paper presents the design, the fabrication and the characterization of a planar interleaved micro-transformer with an Yttrium Iron Garnet (YIG) core. The design of this micro-transformer and the manufacturing steps are presented. HFSS software is used for the conception and the simulation of the interleaved magnetic micro-transformer. It is composed of two identical windings. A bottom magnetic core is used to improve the integrated transformer performances. To form the windings, we have used a surface micromachining process. We have also used a negative photoresist (SU-8) as an insulating layer and as support for the fabrication of a bridge to connect the central end of the coils to the ground shield. The micro-transformer have been characterized with impedance meter up to 100 MHz, and completed to 1 GHz using vector network analyzer.     

Determination of Chromium (VI) in Airborne Particulate Matter by Electrothermal Atomic Absorption Spectrometry

Hexavalent chromium Cr(VI) is a well-established carcinogen associated with lung, nasal, and sinus cancer. Cr(VI) threshold limit values in workroom air have been recently lowered. Consequently, the currently available analytical methods are insufficiently sensitive or high cost. In this paper, a simple, cost-effective, sensitive, and reproducible method using solid-phase extraction with electrothermal atomic absorption spectrometry for determination of hexavalent chromium in airborne samples is reported. The method validation included selectivity, linearity, accuracy, and precision. Interferences from other ions likely to be present in airborne samples, including trivalent chromium, were tested and selectivity was demonstrated. The detection and quantification limits were, respectively, as low as 0.1 and 0.4?µg?L^?1. The linearity ranged from 0.5 to 50.0?µg?L^?1, with a regression coefficients exceeding 0.998. The extraction recovery exceeded 98%. The developed method was successfully compared with a reference spectrophotometric method. The performances achieved were similar to ion chromatography and high-performance liquid chromatography approaches. The novel method was tested on airborne samples collected from the workplace. The method’s performance suggests that it may be an alternative to high-cost techniques for monitoring occupational exposure to hexavalent chromium.     

Graphical Representations of Speed: Obstacles Preservice K‐8 Teachers Experience

This study examines the difficulties college students experience when creating and interpreting graphs in which speed is one of the variables. Nineteen students, all preservice elementary or middle school teachers, completed an upper‐level course exploring algebraic concepts. Although all of these preservice teachers had previously completed several mathematics courses, including calculus, they demonstrated widespread misconceptions about the variable speed. This study identifies four cognitive obstacles held by the students, provides excerpts of their graphical constructions and verbal interpretations, and discusses potential causes for the confusion. In particular, misconceptions arose when students interpreted the behavior and nature of speed within a graphical context, as well as in situations where they were required to construct a graph involving speed as a variable. The study concludes by offering implications for the teaching and learning of speed and its interpretation within a graphical setting.     

Linear and Bilinear Multiplier Operators for the Dunkl Transform

The main purpose of this article is to study the L _p -boundedness of linear and bilinear multiplier operators for the Dunkl transform in the one dimensional case.     

Copper and iron interactions with angiotensin-converting enzyme inhibitors. A study by fast-atom bombardment tandem mass spectrometry

Fast atom bombardment, combined with high-energy collision-induced tandem mass spectrometry, has been used to investigate gas-phase metal-ion interactions with captopril, enalaprilat and lisinopril, all angiotensin-converting enzyme inhibitors.Suggestions for the location of metal-binding sites are presented. For captopril, metal binding occurs most likely at both the sulphur and the nitrogen atom. For enalaprilat and lisinopril, binding preferably occurs at the amine nitrogen. Copyright 1999 John Wiley & Sons, Ltd.     

Laser micro-machining of small objects for high-energy laser experiments

Targets for high-energy laser experiments are polymer or metal objects of small dimensions. These objects need high-precision processes (typical sizes of a few hundred micrometers with micrometer accuracy). In this paper, some targets for high-energy laser experiments obtained by picosecond Q-switched Nd:YAG laser and KrF excimer laser micro-machining are presented. All of the targets use an original process. Activities include cutting, drilling, and marking elements. A summary of targets made using laser processes will be presented.     

Study on QoS Management for Video Streaming in Vehicular Ad Hoc Network (VANET)

Wireless Personal Communications - Vehicular Ad Hoc Network (VANET) is a particular type of MANET providing various wireless communications such as infrastructure communications and inter-vehicle...     

Network-Level QoS Assurances Through Adaptive Allocation of CDMA Resources

In a Code Division Multiple Access (CDMA) network, multiple Mobile Hosts (MHs) can simultaneously transmit over the wireless channel by using different codes. To assure an acceptable Quality of Service (QoS) for all MHs' flows, the network usually tunes the transmit powers of all MHs to achieve a certain level of signal strength as compared to the noise and the interference (SINR) for each MH. The traditional assumption in power control schemes is that the SINR requirement is statically determined for each MH's flow. In contrast, in this paper, we propose a scheme that dynamically adapts the SINR requirements of MH's flow based on its QoS requirements and the conditions of the wireless channel between the MHs and the base station. As a result of this adaptation, we show that network-level QoS measures such as fraction of packets meeting their delay requirements and energy consumed per packet transmission are significantly better than in a scheme that statically fixes the SINR requirements. We show that the adaptation approach works well for the Matched Filter (MF) and the Minimum Mean Squared Error (MMSE) receivers. Our scheme uses a simple table-driven approach for optimally selecting the target SINR requirement for each MH at run time. The entries in the table are computed off-line using a dynamic programming algorithm with the objective of maximizing a profit function that balances the need for meeting the network-level QoS requirements and the cost of using a particular target SINR for a given transmission. Moncef Elaoud (M'97) received his B.Sc. (1988) his M.Sc. (1990) and his Ph.D. (2000) in electrical an computer engineering from the University of Wisconsin-Madison. He is currently a senior research Scientist at Telcordia Technologies' Applied Research organization. His main research interests are in the areas of quality of service, self-forming and self healing networks, auto-configuration, and mobility management in wireless and ad-hoc networks. Bechir Hamdaoui received the B.S. degrees in both electrical and mechanical engineering, and the M.S. degree in mechanical engineering from the National School of Engineering in Tunis (BAC+6+DEA, ENIT), Tunisia, in 1997 and 1998, respectively. He also received the M.S. degree in electrical and computer engineering from the University of Wiconsin, Madison, WI, in 2002, where he is currently working toward the Ph.D. degree. From 1998 to 1999, he worked as a quality control and planning engineer on power generation plant project under the supervision of FIAT Avio. His research focuses on various aspects in the area of computer networking including mobile networks, wireless communication systems, and ad hoc networks. Parameswaran Ramanathan received the B. Tech degree from the Indian Institute of Technology, Bombay, India, in 1984, and the M. S. E. and Ph. D. degrees from the University of Michigan, Ann Arbor, in 1986 and 1989, respectively. Since 1989, Dr. Ramanathan has been faculty member in the Department of Electrical & Computer Engineering, University of Wisconsin, Madison, where is presently a Full Professor. He leads research projects in the areas of sensor networks and next generation cellular technology. In 1997–98, he took a sabbatical leave to visit research groups at AT&T Laboratories and Telcordia Technologies. Dr. Ramanathan's research interests include wireless and wireline networking, real-time systems, fault-tolerant computing, and distributed systems. He is presently an Associate Editor for IEEE Transactions on Mobile Computing and Elsevier AdHoc Networks Journal. He served as an Associate Editor for IEEE Transactions on Parallel and Distributed Computing from 1996–1999. He has also served on program committees of conferences such as Mobicom, Mobihoc, International Conferences on Distributed Systems and Networks, Distributed Computing Systems, Fault-tolerant Computing Symposium, Real-time Systems Symposium, Conference on Local Computer Networks, and International Conference on Engineering Complex Computer Systems. He was the Finance and Registration Chair for the 1999 Fault-tolerant Computing Symposium. He was the program chairman of the Workshop on Architectures for Real-time Applications, 1994 and the program vice-chair for the International Workshop on Parallel and Distributed Real-time Systems, 1996. He is a member of Association of Computing Machinery and a senior member of IEEE.