Wireless sensor network for helicopter rotor blade vibration monitoring: Requirements definition and technological aspects

The main rotor accounts for the largest vibration source for a helicopter fuselage and its components. However, accurate blade monitoring has been limited due to the practical restrictions on instrumenting rotating blades. The use of Wireless Sensor Networks (WSNs) for real time vibration monitoring promises to deliver a significant contribution to rotor performance monitoring and blade damage identification. This paper discusses the main technological challenges for wireless sensor networks for vibration monitoring on helicopter rotor blades. The first part introduces the context of vibration monitoring on helicopters. Secondly, an overview of the main failure modes for rotor and blades is presented. Based on the requirements for failure modes monitoring, a proposition for a multipurpose sensor network is presented. The network aims to monitor rotor performance, blade integrity and damage accumulation at three different scales referred to as macro layer, meso layer and micro layer. The final part presents the requirements for WSNs design in relation with sensing, processing, communication, actuation and power supply.\u

Evaluation of DECT for low latency real-time industrial control networks

c. 1905. Pale yellow rayon faille Princess line dress with a bobbinet overlay appliquéd with cream wool Art Nouveau lilies and finished with machine-made Chantilly lace flounces, closing in back, with short sleeves and a floor-length skirt. The dress is made from long fitted panels without a waist seam. Eight shaped pieces extend from the bodice to the skirt hem: two narrow front panels with a center seam, two side-front panels, two side-back panels, and two back panels with a center-back opening with twenty hooks. The panels narrow at the waist, curve over the hips and flare to the hem. The bodice portion of the dress is lined with white cotton just past the waist, made with one front panel shaped with two darts, and two back panels with one dart each. The dress has a scooped neckline in front and back, and has close-fitting sleeves ending above the elbow, made with one seam. The overlay is a two-twist bobbinet appliquéd before construction. Tightly woven cream wool was machine-sewn to the bobbinet with continuous lengths of pale yellow braided cord outlining columns of large stylized Art Nouveau lilies, stems, and leaves. The wool ground was then carefully cut away from the bobbinet, leaving the floral elements behind, as evidenced in part by a lily at the left front skirt hem missing its interior detail cut on one petal. There are two panels in the overlay, sewn to each other with a free-floating center-front seam and sewn to the dress at the neckline (dipping about 10.2 cm / 4 in. down from the edge at center-front), shoulders, and scyes. The overlay’s center-front seam runs precisely down the middle of a column of lilies, matching flower halves from left and right, and the join is reinforced by retaining the full, continuous length of the wool seam allowance and by leaving the interior details of flowers straddling the seam uncut. The bobbinet is, by its nature, stretchy and so drapes closely to the contours of the dress beneath; the panels wrap diagonally around the sides to the back, pulled up from their straight grain center-front seam into a bias angle in back where the columns of lilies form chevrons where they meet at center. The ends of the panels fold over the edges of the center-back opening of the underlying fabric. This draping results in the overlay skirt coming to a point just above the hem in front and rising almost to waist level in back. A machine-made Chantilly lace flounce, shorter in front and lengthening to the back, is added to the bottom edge of the bobbinet, so that the complete overlay skirt is 99.1 cm / 39 in. long in front as measured from the waistline, and 35.6 cm / 14 in. long in back. In the bodice, the flowers and leaves are applied individually to create a horizontal trim across the neckline, reaching slightly past its edge. At the front, an asymmetrical Chantilly flounce is sewn beneath the appliqué, shorter and fuller on the left side than on the right, hanging to the waist in front and ending in back at the shoulders. A lily is centered at the top of the bodice opening, sewn down on the right side and overlapping the opening to hook closed on the left. The sleeves are covered with the same bobbinet and appliqué, and are finished with a gathered, knotted band of the Chantilly lace. Machine-sewn and hand-sewn.https://scholars.unh.edu/bowen_collection/2008/thumbnail.jp

Evaluation of DECT-ULE for robust communication in dense wireless sensor networks

In today’s world wireless sensor networks (WSNs) have enormous applications which made our everyday life much easier. In most of these applications, the unlicensed 2.4 GHz frequency band has been used for sensor communications. Due to the wide use, the chance of getting interference in this frequency band is quite high. Thus, a reliable and real-time communication in mass WSNs can not be guaranteed, which is essential for industrial applications. In this paper, we evaluate the performance of Digital Enhanced Cordless Telecommunications - Ultra Low Energy (DECT-ULE) for robust communication in dense WSNs and found that it can cope with the limitations of existing standards. We show that DECT-ULE can elegantly handle dense WSNs by allocating communication channels with excellent quality and minimum delay