Lift Off Research Articles

After Lucretius

Previous articleNext article FreeAfter LucretiusJohn WilkinsonJohn Wilkinson Search for more articles by this author PDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinked InRedditEmailQR Code SectionsMore29 April 2020The lights have fallen dumb and refuse to travel,preserving their angles is all that concerns them;clothes hang in their creases, while in seed-banksweevils curl up at the futility of spoiling green further.This time had been expected to have legs, to moveformations across the plain. This time believes lovea moving force, but takes delight and bandages it,runs closed captioning behind closed doors. What ifan elevator loses purpose, flashlights fail to search,if empty buses void the timetable – did you surviveRome’s marauding gangs, did you survive plague?Lovers take turns round apartments, seek to bringstars to earth, starring the recesses of bodies plainlyfelt, might that stop the fever? – Courses deviate,the very bricks lift off to touch skin, skin will floatsong that pulmonary rises, falls and rises in the street.NotesJohn Wilkinson is professor in the Department of English at the University of Chicago and director of the program in Creative Writing and the program in Poetry and Poetics. Previous articleNext article DetailsFiguresReferencesCited by Critical Inquiry Volume 47, Number S2Winter 2021Posts from the PandemicEdited by Hank Scotch Article DOIhttps://doi.org/10.1086/711445 Views: 583 © 2021 by The University of Chicago. All rights reserved.PDF download Crossref reports no articles citing this article.

The execution of movement: a spinal affair.

In this tribute to Reggie Edgerton, I briefly review the spinal mechanisms that coordinate locomotion and the interaction between the different sensory mechanisms that help coordinate the locomotor movements and the central locomotor network. The step cycle has four distinct parts, the support phase, the lift off, the flexion phase, and, the most complex, the touch down, when the limb makes a smooth contact with ground again. Each of these phases is affected by different sensory mechanisms, which interact with the central network [central pattern generator (CPG)] generating the basic movements with its four components. Conversely, the CPG also gates the sensory reflex pathways, so that they are active only in a given phase of the step cycle, or even produces opposite effects in different parts of the step cycle. These different examples from mammals are most likely important also to consider for human locomotion and, in particular, in patients with spinal cord injury, partial or complete.

Janet Yellen's Lift Off

Half way through her terms as Fed chair, Janet Yellen presided over the Fed’s controversial decision to start raising interest rates — a decision many viewed then, and many more view now, as premature. Was that decision consistent with Yellen's supposed commitment to full employment? Or was she instead a hawk in dove’s clothing, whose monetary overtightening kept millions out of work for no good reason? I argue that neither view is correct. Instead, the roots of the Fed's untimely rate hike, and Yellen's part in it, lay in her and other Fed officials’ ill-conceived plans for “normalizing” monetary policy.

The Optimum Distance of Lift Off Height on Different Test Material’s Thickness by using Eddy Current Testing Technique

The Eddy current testing (ECT) technique is one of the non-destructive testing (NDT) techniques which is sensitive to the unintended signal such as lift-off (LO) height effect. The output voltage of signal defects with different thicknesses of test materials (i.e., Copper, Brass and Magnesium Alloy) can be determined from the optimum distance of LO height of the ECT technique. Previously, an established frequency was determined for these particular materials (i.e., Copper = (5.00-5.25) MHz, Brass = (4.75-5.25)MHz and Magnesium Alloy= (4.75-5.00)MHz). The frequency then generated the established voltage signal of the ECT technique. The acquired optimum distance of LO height for these materials is approximately 2mm. The findings from this established technique indicated that the determined optimum distance of LO height can find the output voltage signal of the defects as well as to detect the thicknesses.

Impact of Water Content in NMP on Ohmic Contacts in GaN HEMT Technologies

Wet chemical lift off in N-Methyl-2-pyrrolidone (NMP) is widely used in GaN HEMT Front End manufacturing. In case of a Ti-Al-Ni-Au based metal stack for ohmic contacts, the quality of the lift-off process is a strong function of the water content in the solvent NMP. In this article, it will be shown that the metal stack can be attacked during lift off in NMP when its water content is exceeding 5%. Additionally, environmental impacts on the hygroscopy of NMP are investigated. Both temperature of NMP and its contact area to air impact the evolution of its water content. Based on these investigations, the lift off sequence was slightly adapted in order to keep moisture below a certain level and avoid optical defects on ohmic contacts.

A computational study into the effect of the winglets on the performance of fully submerged hydrofoils

Hydrofoil vessels, which greatly take the advantage of the dynamic lifting force during the cruising, are amongst the watercrafts that can significantly benefit from the application of the winglets. These benefits can be decreasing the lift off speed of the vessel, increasing its maximum speed or reducing the drag force acting on the hydrofoils and hence contributing to fuel saving.This study aims to provide a basic understanding of the benefits of the usage of the winglets for the fully submerged hydrofoils of a marine vessel. In accordance with this purpose, the performance of several winglets, which were generated based on the Withcomb's winglet design, was analysed by means of RANS computations. The effect of the chord length, span, cant angle, trailing edge sweep angle of the winglets and effective span of the hydrofoil/winglet system was systematically investigated. Detailed information about the topological features of the flow around the hydrofoil and winglets were provided. The influence of the flow structure on the performance and generation of the lift was extensively discussed. The computations revealed the effectiveness of the usage of the winglets.

Subacromial impingement syndrome: a survey of Italian physiotherapists and orthopaedics on diagnostic strategies and management modalities

Background and aimThe subacromial impingement syndrome (SIS) represents a common cause of disability in approximately 74% of patients with Shoulder Pain (SP). Even if contemporary research suggests that this mechanism is not (always) the dominant driver in SP, SIS is still a source of debate among scholars and clinicians. From a clinical point of view, evidence has suggested that clinicians can use both medical and physiotherapy approaches as effective methods to treat SIS.This survey aims to investigate models of management of patients with SIS in a sample of Italian physiotherapist specialists (Orthopaedic Manipulative Physical Therapists, −OMPTs-) and orthopaedic surgeons.Materials and methodsAn online survey with 29-item questionnaire was administered to assess the knowledge of OMPTs and orthopaedic surgeons about: a) strategies of clinical examination; b) the role of imaging in the diagnostic process; c) the physiotherapy management; and d) the pharmacological and surgical management in patients with SIS.ResultsSix-hundred and twenty-nine respondents completed the survey (511 OMPTs (79.97%) and 128 orthopaedic surgeons (20.03%)). Ninety-two percent (n = 470) of the OMPTs and 80.5% (n = 103) of orthopaedic surgeons stated that in patients with SIS, a combination of diagnostic tests produced better accuracy (p = < 0.001). Twenty point seven % of OMPTs (n = 106) and 4.7% of orthopaedic surgeon (n = 6) stated that the Lift off was the most specific test (p = < 0.001). Four-hundred-and-twenty-four OMPTs (83%) and 40 orthopaedic surgeons (31.3%) answered that the gold standard for diagnosis of a patient with SIS are history and clinical examination (p < 0.001).ConclusionOMPTs and orthopaedic surgeons approach patients with SIS differently during both the assessment and the treatment. OMPTs appear to be appropriate in planning and managing clinical examination and therapeutic strategies to use with patients with SIS.

Film cooling performance and flow field of compounded double jet holes with trench

Film cooling performance of a novel double jet configuration is numerically analysed. The proposed scheme has a primary compound angle hole along with a secondary hole compounded in the laterally opposite direction. The primary hole is provided with a trench at the coolant hole exit. Numerical analysis is performed using RANS equations along with standard k-ω turbulence model. The numerical scheme is validated through the excellent agreement between the available experimental data for tangential, compound, and crater designs having similar primary hole geometric parameters. It is seen that the proposed compounded double jet trench design (DJT) combines the advantages of compound angle, double jet and trenched configurations and provides better lateral and uniform coolant distribution, reduced jet lift off, and higher coolant attachment in the stream wise direction. The vortex mechanisms responsible for the coolant spread in near-hole and down stream regions are identified. The various flow structures that are responsible for higher effectiveness are compared with other configurations. The effect of free stream turbulence at various blowing ratios is studied and found that the increase of turbulence produced significant increase in lateral effectiveness at higher blowing ratios. This effect is predominant at far downstream locations of the coolant exit plane.

Age-Related Differences in Arm and Trunk Responses to First and Repeated Exposure to Laterally Induced Imbalances.

The objective of this study was to examine age-related differences in arm and trunk responses during first and repeated step induced balance perturbations. Young and older adults received 10 trials of unpredictable lateral platform translations. Outcomes included maximum arm and trunk displacement within 1 s of perturbation and at first foot lift off (FFLO), arm and neck muscle activity as recorded using electromyography (EMG), initial step type, balance confidence, and percentage of harness-assisted trials. Compared to young adults, older adults demonstrated greater arm and trunk angular displacements during the first trial, which were present at FFLO and negatively associated with balance confidence. Unlike young adults, recovery steps in older adults were directed towards the fall with a narrowed base of support. Over repeated trials, rapid habituation of first-trial responses of bilateral arm and trunk displacement and EMG amplitude was demonstrated in young adults, but was absent or limited in older adults. Older adults also relied more on harness assistance during balance recovery. Exaggerated arm and trunk responses to sudden lateral balance perturbations in older adults appear to influence step type and balance recovery. Associations of these persistently amplified movements with an increased reliance on harness assistance suggest that training to reduce these deficits could have positive effects in older adults with and without neurological disorders.

9‐2: Manufacturing Process for Mass Production of Micro‐LED Displays and High‐Speed and High‐Yield Laser Lift‐Off Systems

In our previous work, we proposed and evaluated processes and equipment to facilitate the mass production of micro LED (light emitting diode) displays. The new technologies include LLO (laser lift off), mass‐transfer, color conversion and backplane with micro Si chip. We quantitatively evaluated them and report results.

Lift off!

Lift off!

Life after lockdown: making workplaces safer

Considering the relentless nature of spread of COVID-19 with no end in sight, many countries have now decided to lift off some restrictions and allow some non-essential services, at least in those areas which are not severely hit by COVID-19. Lack of planning for reopening can result in a cascade of failures as employers are not aware of how to address challenges of COVID-19 with limited resources under pandemic conditions. Undoubtedly this demands lots of modifications at the workplaces that will require various strategies including primarily development and implementation of the plan and maintaining and revising it from time to time. Thorough literature search was conducted for this purpose on varied search engines applying key terms as ‘COVID-19’ and ‘return to work’ and ‘safe workplaces’ and ‘life after lockdown’ which revealed different elaborate guidelines framed by various competent authorities in relation to reopening workplaces after lockdown of COVID-19 pandemic. The current review is an attempt towards combining and presenting broad guidelines for workplaces in a simplified manner.

Wind load effect on the lateral instability of precast beams on elastomeric bearing supports

Abstract The behavior of slender precast beams related to lateral stability in the transitional and in service phases is worrying. The presence of geometric imperfections aggravates and makes the problems of instability more susceptible. The main objective of this work is to evaluate the behavior of concrete beams on elastomeric bearings and to analyze the influence of variables such as: concrete strength, wind load and bearing compression stiffness. For the numerical nonlinear analysis the software ANSYS based on the Finite Element Method was used. The analyses show that the influence of the strength of the concrete is significant in the lateral stability of the beam. The wind load represents a considerable decrease in the contact (lift off) between the beam and the bearing. Finally, the combination of these factors can result in a critical stress situation in the beam, and it is not possible to have equilibrium, causing its toppling.

Research on the Weld Position Detection for the T-Joints in Web-Core Sandwich Panels Based on Eddy Current Technology.

Web-core sandwich panels have gained the popularity in various fields, especially aviation and shipbuilding, etc. Penetration welding was considered as an effective process to manufacture such a structure through a T-joint. To ensure the formation quality and mechanical properties of weld, the welding torch needs to be aligned with the T-joint position. However, it is difficult to locate the T-joint position (i.e., the position of core panel) because of the shielding of the face panels. This paper investigated the detection of T-joint position from the face panel side in web-core sandwich panels based on eddy current technology. First, we designed an experimental system for the weld position detection of T-joints from the face panel side. The relationships are investigated between the characteristics of the eddy current detection signal and the primary parameters of the detection system (including excitation frequency, coil outer diameter, and lift off distance) and the T-joint (including thickness of the core panel, gap distance, and thickness of the cover panel). Corresponding experiments were carried out with variable primary parameters, and the influence mechanism of the primary parameters on the detection results in terms of sensitivity and dynamic performance was elaborated to set up the theoretical basis for the detection. Finally, weld position detection experiments were carried out on TC4 titanium alloy T-joint specimens with 3 mm-thick face panel and 5 mm-thick core panel. Results showed that the maximum detection error was 0.482 mm, and the average error was 0.234 mm. This paper provided a possible technical solution to the automatic tracking problem for the welding of T-joints in the web-core sandwich panels.

High speed etching of silicon in KOH + NH 2 OH solution at lower temperatures for the fabrication of through holes in silicon wafer

In the fabrication of complicated MEMS inertial sensors, there are many instances where metallisation cannot be done by usual methods such as lift off or conventional metal etch. In such cases, a shadow mask needs to be used. A silicon shadow mask can be realised by the fabrication of through holes in silicon. This also can be used as a cover wafer for wafer level encapsulation by fabricating a cavity in the device region. The fabrication of the shadow mask is carried out by doing double side wet anisotropic etching using potassium hydroxide (KOH) + hydroxylamine (NH2 OH) solution at low temperatures of 50–60°C. The low temperature of etching is preferred so as to reduce the etching of thermal oxide used as a mask layer. This work focuses on the etching characteristics of the KOH + NH2 OH solution at low temperatures in terms of etch rate, undercutting, surface morphology, and selectivity of an oxide layer with silicon. This is very useful in through hole etching using silicon dioxide as a mask. The effect of aging on these characteristics is also studied and this is useful in continuous etching spread over few days especially during pilot production. The results are compared with those obtained using a pure KOH solution.

LO19: AED on the fly: A drone delivery feasibility study for rural and remote out-of-hospital cardiac arrest

Introduction: Time-to-treatment plays a pivotal role in survival from sudden cardiac arrest (SCA). Every minute delay in defibrillation results in a 7-10% reduction in survival. This is particularly problematic in rural and remote regions, where bystander and EMS response is often prolonged and automated external defibrillators (AED) are often not available. Our objective was to examine the feasibility of a novel AED drone delivery method for rural and remote SCA. A secondary objective was to compare times between AED drone delivery and ambulance response to various mock SCA resuscitations. Methods: We conducted 6 simulations in two different rural communities in southern Ontario. During phase 1 (4 simulations) a “mock” call was placed to 911 and a single AED drone and an ambulance were simultaneously dispatched from the same location to a pre-determined destination. Once on scene, trained first responders retrieved the AED from the drone and initiated resuscitative efforts on a manikin. The second phase (2 scenarios) were done in a similar manner save for the drone being dispatched from a regionally optimized location for drone response. Results: Phase 1: The distance from dispatch location to scene varied from 6.6 km to 8.8 km. Mean (SD) response time from 911 call to scene arrival was 11.2 (+/- 1.0) minutes for EMS compared to 8.1 (+/- 0.1) for AED drone delivery. In all four simulations, the AED drone arrived before EMS, ranging from 2.1 to 4.4 minutes faster. The mean time for trained responders to retrieve the AED and apply it to the manikin was 35 (+/- 5) sec. No difficulties were encountered in drone activation by dispatch, drone lift off, landing or removal of the AED from the drone by responders. Phase 2: The ambulance response distance was 20km compared to 9km for the drone. Drones were faster to arrival at the scene by 7 minutes and 8 minutes with AED application 6 and 7 minutes prior to ambulance respectively. Conclusion: This implementation study suggests AED drone delivery is feasible with improvements in response time during a simulated SCA scenario. These results suggest the potential for AED drone delivery to decrease time to first defibrillation in rural and remote communities. Further research is required to determine the appropriate distance for drone delivery of an AED in an integrated EMS system as well as optimal strategies to simplify bystander application of a drone delivered AED.

Seismic models of detachment and faulted detachment folds

Abstract Detachment folds constitute a common structural style in fold-thrust belts and typically form in stratigraphic packages defined by relatively competent cover units underlain by ductile units. PSTM images through these structures contain artifacts resulting from lateral velocity variations between the cover sediments and the core units, steep dips, and complex fold-fault relationships, making them difficult to interpret. Understanding these artifacts and pitfalls in PSTM seismic models enables improved interpretations of PSTM data in natural structures. We conducted 2D seismic modeling for detachment folds models to study the effect of these complexities on PSTM data. Seismic “pull-ups” and “push-downs” of the strata underneath the salt or shale substrate are related to the relative velocities of the cover sediments and the core units. A specific example of an Appalachian Plateau structure demonstrates how the relative velocities can influence the seismic image. Progressive evolution of the structures to disharmonic and lift off folds results in enhanced “pull-ups” and poorer imaging of steep limb segments. For faulted detachment folds, faulted limbs and footwall zones are poorly imaged and marked by wide low-reflectivity bands, making fault interpretation difficult.

Simple trilayer metamaterial absorber associated with Fano-like resonance

A simple metamaterial absorber suitable for fabrication over large areas associated with a Fano like resonance is proposed. The proposed designed of the metamaterial absorber consists of photoresist disk arrays on a silicon substrate followed by the deposition of a tri layer of Au, ZnS and Au on the top of the structure. Due to the tri layer, there is a formation of a cavity between the substrate and gold layer on the top of photoresist disk and a waveguide in the ZnS layer in between the gold layers on the substrate and the ZnS layer itself. The Fano like resonance arises due to the interference of the cavity mode and the guided-mode resonance as well as the Woods anomaly. The cavity mode resonance works as continuum mode whereas the guided mode resonance and Woods anomaly work as discrete modes. The spectral position of the resonance can be tuned by just controlling the thickness of the tri layer instead of the structural size and shape modification of the micro and nano-structures as usually done in conventional metamaterial absorbers. This design can be easily scaled for fabrication over large areas as it separates the structuring and deposition processes and makes them sequential thereby avoiding expensive and complex lift off or etching processes which are usually required for conventional metamaterial processing.

2D Layered Graphene Oxide Films Integrated with Micro-Ring Resonators for Enhanced Nonlinear Optics.

Layered 2D graphene oxide (GO) films are integrated with micro-ring resonators (MRRs) to experimentally demonstrate enhanced nonlinear optics. Both uniformly coated (1-5 layers) and patterned (10-50 layers) GO films are integrated on complementary-metal-oxide-semiconductor (CMOS)-compatible doped silica MRRs using a large-area, transfer-free, layer-by-layer GO coating method with precise control of the film thickness. The patterned devices further employ photolithography and lift-off processes to enable precise control of the film placement and coating length. Four-wave-mixing (FWM) measurements for different pump powers and resonant wavelengths show a significant improvement in efficiency of ≈7.6 dB for a uniformly coated device with 1 GO layer and ≈10.3 dB for a patterned device with 50 GO layers. The measurements agree well with theory, with the enhancement in FWM efficiency resulting from the high Kerr nonlinearity and low loss of the GO films combined with the strong light-matter interaction within the MRRs. The dependence of GO's third-order nonlinearity on layer number and pump power is also extracted from the FWM measurements, revealing interesting physical insights about the evolution of the GO films from 2D monolayers to quasi bulk-like behavior. These results confirm the high nonlinear optical performance of integrated photonic resonators incorporated with 2D layered GO films.

Eddy Current Testing Technique to Detect Imperfection Surface for Different Lift-off Value on Copper Metal

Non-Destructive Testing (NDT) known as the evaluation of properties of a wide variety of materials without causing a damaged despite after inspection is done and the material still can be used. This paper aims for a designed NDT metal instrument that is conducted using eddy current testing (ECT) technique to find an applicable lift-off (LO) value in detecting imperfection. A dual sensor was designed consist of excitation coil was applied to evaluate the surface imperfections or other excitation frequencies in controlling the signal responses from the testing material, copper (Cu) with dimension of 100 mm x 100 mm installed with artificial surface imperfection (i.e., 7 mm, 14 mm and 21 mm) was main subject in this study. An established amplifier consisting of a specific op-amp was used to boost up the voltage of the alternate current (AC). The data of setting frequencies was ranged from 5.00 - 5.25 MHz was recorded varied of the LO values (i.e., 1.0 mm, 2.0 mm, 3.0 mm, 4.0 mm and 5.0 mm). Based on the frequencies applied the result for an applicable LO value acquires the promising result of reading signal was around 2 mm and the imperfection detection performance obtained a larger voltage gradient with the increase of the imperfection sizes. The study concludes that the developed non-destructive metal testing instrument of specific ECT design by using the excitation coil is appropriate in measuring the LO value and could be used to find different imperfection for metal.