A novel design for an RF MEMS resistive switch on PCB substrate

Copyright @ 2008 Stimulation Action on MEM

The scope of the EU VAT Directive: Transactions carried out via Video Sharing Websites

Video Sharing Websites constitute a rather peculiar situation. On one hand, they are considered as part of what the Commission perceives as online sharing economy: users are eligible to derive income from monetizing their audiovisual content. On the other hand, their business model is reminiscent of what is described as “free -economy”: access to the audiovisual content is prima facie provided without any monetary consideration. While the Commission has published guidelines, in an effort to map the potential issues regarding the VAT Treatment of persons who conduct activities via sharing economy online platforms, its assessment focalized more on “digitalized” traditional activities. This inquiry is dedicated to raising the issues concerning the qualification as “supplies of goods or services for consideration”, of activities carried out via Video Sharing Websites, and of their provider as “taxable person”, for the purposes of EU VAT, in the light of the EU VAT Directive and the CJEU’s interpretation of these concept

Analysis and design of an all metal in line series ohmic RF MEMS switch for microwave applications

Copyright © 2010 IEEE. Reprinted from IEEE Conference Proceedings. This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.Abstract: - This paper presents the analysis, design and simulation of an all metal in line series ohmic RF MEMS switch. The proposed switch is indented to be used in the frequency range between DC and 10GHz. The switching characteristics of the proposed switch fulfill all the requirements as concerns loss, isolation, linearity, power handling and small size/power consumption. The specific design of the cantilever (hammerhead) and the distributed actuation force ensure the reliability and the controllability of the switch and the relatively simple design (all metal) the robustness and high fabrication yield

Novel approaches in voltage-follower design

The aim of this research programme was to design and develop novel voltagefollowerslbuffers, suitable for radio frequency (RF) applications. The emphases throughout has been on improving key characteristics, in particular distortion, operating bandwidth, input and output impedances, offset-voltage and power supply demands of the design. The majority of the results of this work have been reported by the author in the technical literature (I] to (6). Initially this research focuses on the investigation of the underlying operating principles of the voltage-follower to provide an in-depth understanding of its operation. This study concentrates on establishing reasons for the poor distortion, low input and high output impedances and increased offset-voltage and confirmed that these designs have inherently poor performance in these parameters. The analysis is carried out using both theoretical modelling and computer simulation, using the wellestablished software package ORCAD PSpice. Despite the availability of high performance computer simulation tools, it becomes apparent that 'hand' calculations in the design process, generally based on DC and small-signal transistor parameters, are essential. Therefore a detailed analysis of the transistor-models used throughout this research is carried out with PSpice data. Using the analytical results of the conventional voltage-follower as a benchmark, various novel circuit techniques investigated. Several new circuits are proposed with respect to improving the previously mentioned key characteristics. The first technique comprises local feedback and single-valued current biasing and 111 consists of emitter-followers exclusively throughout the signal path, keeping the distortion of the input signal to low levels [1 J, (2). The second technique is based on local feedback with double-valued current biasing, increasing somewhat the power dissipation but reducing, notably, the distortion of the configuration [3J, [4J, [5J, [6J. The final technique employs the emitter-followers throughout the signal path in combination with global feedback and double-valued current biasing, which presents significantly better results, on certain parameters, than conventional and existing configurations. It is anticipated that this work will be published in the near future

CernVM Online and Cloud Gateway: a uniform interface for CernVM contextualization and deployment

In a virtualized environment, contextualization is the process of configuring a VM instance for the needs of various deployment use cases. Contextualization in CernVM can be done by passing a handwritten context to the user data field of cloud APIs, when running CernVM on the cloud, or by using CernVM web interface when running the VM locally. CernVM Online is a publicly accessible web interface that unifies these two procedures. A user is able to define, store and share CernVM contexts using CernVM Online and then apply them either in a cloud by using CernVM Cloud Gateway or on a local VM with the single-step pairing mechanism. CernVM Cloud Gateway is a distributed system that provides a single interface to use multiple and different clouds (by location or type, private or public). Cloud gateway has been so far integrated with OpenNebula, CloudStack and EC2 tools interfaces. A user, with access to a number of clouds, can run CernVM cloud agents that will communicate with these clouds using their interfaces, and then use one single interface to deploy and scale CernVM clusters. CernVM clusters are defined in CernVM Online and consist of a set of CernVM instances that are contextualized and can communicate with each other.Comment: Conference paper at the 2013 Computing in High Energy Physics (CHEP) Conference, Amsterda

Improving controllability in RF-MEMS switches using resistive damping

An efficient way to control the impact velocity in order to achieve soft landing and fewer bouncing phenomena is the resistive damping. This control method is also referred as charge drive and presented for first time by Castaner and Senturia [1]. Under charge control the Pull-in phenomenon of the Constant Voltage controlled electrostatic actuators does not exist and if the current drive is ideal, any position across the gap is stable. The main reason for this behavior is that the electrostatic force applied is always attractive and independent of the remaining gap of the actuator. Charge drive control incorporating constant current sources is mostly preferred to extend the travel range of electrostatic micro-actuators [2], [3], [4], [5]. Nevertheless there are very few references in the literature about charge drive control on RF MEMS. Recently published work based on numerical simulations for capacitive RF-MEMS, [6] and [7] present a learning algorithm in order to reduce fabrication variability using resistive damping for the pull-down phase. Nevertheless none of them present any details on how to implement resistive damping and any results of such kind of applications. This work presents in detail the entire procedure in calculating the bias resistance of an RFMEMS switch controlled under resistive damping

Skyrmions, Rational Maps & Scaling Identities

Starting from approximate Skyrmion solutions obtained using the rational map ansatz, improved approximate Skyrmions are constructed using scaling arguments. Although the energy improvement is small, the change of shape clarifies whether the true Skyrmions are more oblate or prolate.Comment: 13 pages, 3 figure

A collaborative citizen science platform for real-time volunteer computing and games

Volunteer computing (VC) or distributed computing projects are common in the citizen cyberscience (CCS) community and present extensive opportunities for scientists to make use of computing power donated by volunteers to undertake large-scale scientific computing tasks. Volunteer computing is generally a non-interactive process for those contributing computing resources to a project whereas volunteer thinking (VT) or distributed thinking, which allows volunteers to participate interactively in citizen cyberscience projects to solve human computation tasks. In this paper we describe the integration of three tools, the Virtual Atom Smasher (VAS) game developed by CERN, LiveQ, a job distribution middleware, and CitizenGrid, an online platform for hosting and providing computation to CCS projects. This integration demonstrates the combining of volunteer computing and volunteer thinking to help address the scientific and educational goals of games like VAS. The paper introduces the three tools and provides details of the integration process along with further potential usage scenarios for the resulting platform.Comment: 12 pages, 13 figure

Idiopathic scoliosis : aspects on surgical and non-surgical treatment

The term scoliosis has been used to describe conditions that lead to deformation of the spine. It derives from the ancient Greek ‘σκολίωσις’ and the root word ‘σκολιός’ which means ‘bent or crooked’. In its most common form, scoliosis is of unknown - idiopathic - cause and origin. It affects roughly 3% of children and adolescents during growth and in mild cases no treatment is required. In moderate cases, bracing has been proposed, with the aim to halt progression of idiopathic scoliosis. It is most common with full-time bracing using rigid, custom made thoracolumbosacral orthoses. It is worn for 16-20 hours per day until skeletal maturity and has been shown to prevent scoliosis progression to a surgical threshold in about 70% of the cases. However, compliance to the treatment has been one of the major drawbacks seen with the full-time brace. Therefore, night-time braces, worn only during the night, have started to gain popularity over the years. Nevertheless, evidence on the effectiveness of night-time bracing has only been based on retrospective studies. More recently, specific scoliosis exercise regimes consisting of self-mediated correction maneuvers in 3 dimensions have also emerged. So far, there has been only one high quality study showing effectiveness of this modality, in patients with mild idiopathic scoliosis. A trial was performed consisting of 135 patients randomized to self-mediated physical activity in combination with either night-time brace, or scoliosis-specific exercise, or self-mediated physical activity alone. Night-time brace was shown to be more effective than self-mediated physical activity in preventing scoliosis progression. On the other hand, scoliosis-specific exercise did not show any clinical benefit when compared to the self-mediated physical activity. Additionally, comparison between the nigh-time brace group and a group of patients who declined participation in the trial and received a full-time brace showed similar effectiveness on the prevention of curve progression. In case the deformity progresses to more severe curves, surgery may be suggested. Over the last decades, a posterior exposure to the spine with a high number of implants and predominantly pedicle screw based fixation techniques has been favored over traditional techniques with low number of implants for the correction of scoliosis. These techniques have been suggested to increase correction and fusion rates and eliminate the risks associated with exposure of the chest wall and/or abdomen in anterior approaches to the spine. Disadvantages of the posterior approach to the spine include extended muscle dissection, need for a higher number of vertebrae to be fused and risk for neurological injuries to the spinal cord. To date, whether posterior based fusion may result in better clinical and radiographic outcomes compared to anterior fusion is still unclear. Moreover, whether higher number of implants per vertebra (implant density) results in better clinical and radiographic outcomes is still debatable. In a nationwide registry-based cohort, we identified patients who underwent anterior (n=27) and posterior (n=32) fusion surgery for a thoracolumbar/lumbar type of scoliosis. We found that despite a longer operative time in the anterior group and higher blood loss and longer fusion constructs in the posterior group, both procedures resulted in significant correction of the scoliosis with similar patient-reported outcome and satisfaction; suggesting that the type of approach is not related to health-reported quality of life. By using the same nationwide database, we also identified 328 surgically treated idiopathic scoliosis patients who were then divided into tertiles based on the number of implants used per operated vertebra. We found no differences in the correction rate of the curve and health-reported quality of life in the different tertiles, suggesting that a high number of implants is not necessarily beneficial in the surgical treatment of idiopathic scoliosis. Studies have shown that, what is perceived as successful radiographic outcome, may not necessarily correlate with patient´s own perception of successful outcome after surgery for idiopathic scoliosis. Patients may still experience persistent back pain and worse quality of life, despite an excellent radiographic outcome. By using the same nationwide database, we identified 280 patients treated with posterior fusion surgery for idiopathic scoliosis and divided them into a high (n=67) and a low (=213) postoperative pain group, based on their self-reported postoperative back pain scores. We found that patients in the high pain group also reported higher back pain and worse quality of life before surgery, compared to the low postoperative pain group. High preoperative back pain and low preoperative mental health were identified as predictors of persistent pain after surgery