scholarly journals Top Coating Anti-Erosion Performance Analysis in Wind Turbine Blades Depending on Relative Acoustic Impedance. Part 1: Modelling Approach

Coatings ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 685 ◽  
Author(s):  
Luis Domenech ◽  
Jordi Renau ◽  
Asta Šakalytė ◽  
Fernando Sánchez
Keyword(s):  
Speed Of Sound ◽  
Turbine Blades ◽  
Multilayer Coating ◽  
Material Behavior ◽  
Acoustic Properties ◽  
High Rate ◽  
Viscoelastic Materials ◽  
Transient Pressure ◽  
Damage Initiation ◽  
The Impact

Top coating are usually moulded, painted or sprayed onto the wind blade Leading-Edge surface to prevent rain erosion due to transverse repeated droplet impacts. Wear fatigue failure analysis based on Springer model has been widely referenced and validated to quantitatively predict damage initiation. The model requires liquid, coating and substrate speed of sound measurements as constant input parameters to define analytically the shockwave progression due to their relative vibro-acoustic properties. The modelling assumes a pure elastic material behavior during the impact event. Recent coating technologies applied to prevent erosion are based on viscoelastic materials and develop high-rate transient pressure build-up and a subsequent relaxation in a range of strain rates. In order to analyze the erosion performance by using Springer model, appropriate impedance characterization for such viscoelastic materials is then required and represents the main objective of this work to avoid lack of accuracy. In the first part of this research, it is proposed a modelling methodology that allows one to evaluate the frequency dependent strain-stress behavior of the multilayer coating system under single droplet impingement. The computational tool ponders the operational conditions (impact velocity, droplet size, layer thickness, etc.) with the appropriate variable working frequency range for the speed of sound measurements. The second part of this research defines in a complementary paper, the ultrasonic testing characterization of different viscoelastic coatings and the methodology validation. The modelling framework is then used to identify suitable coating and substrate combinations due to their acoustic matching optimization and to analyze the anti-erosion performance of the coating protection system.

scholarly journals The Contribution of Infrared Thermography in the Characterization of Glass/Epoxy Laminates through Remote Sensing of Thermal-Stress Coupled Effects

Proceedings ◽  
2019 ◽  
Vol 15 (1) ◽  
pp. 21
Author(s):  
Carosena Meola ◽  
Simone Boccardi ◽  
Giovanni Maria Carlomagno
Keyword(s):  
Cantilever Beam ◽  
Mechanical Stresses ◽  
Material Behavior ◽  
Low Velocity Impact ◽  
Imaging Device ◽  
Temperature Variations ◽  
Thermal Images ◽  
Damage Initiation ◽  
Matrix Cracks ◽  
The Impact

Mechanical stresses of materials are generally coupled with temperature variations and then, monitoring such variations can help gaining information about the material behavior under the applied loads. This can be accomplished with an infrared imaging device, which can be advantageously exploited to sense the thermal radiation associated with mechanical stresses and to obtain a legible explicative temperature map. In the present paper, glass/epoxy is used as material case study to show that thermal signatures visualized during the load application can be decoded into knowledge, which can contribute to the material characterization. In particular, glass/epoxy specimens are subjected to three types of tests: cantilever beam alternate bending, quasi-static bending and low velocity impact. Thermal images are acquired in time sequence during each test and after post-processed and analyzed. It is possible to get data about the damage initiation and its evolution under either quasi-static bending, or impact. In particular, a cute analysis of thermal images supplies information about damage types (matrix cracks, or fibers breakage) and extension of delamination, as well of the impact duration and the time to reach peak contact force. It is also possible to well depict the harmonic cantilever beam oscillations through the associated small temperature variations.

scholarly journals Top Coating Anti-Erosion Performance Analysis in Wind Turbine Blades Depending on Relative Acoustic Impedance. Part 2: Material Characterization and Rain Erosion Testing Evaluation

Coatings ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 709
Author(s):  
Luis Domenech ◽  
Víctor García-Peñas ◽  
Asta Šakalytė ◽  
Divya Puthukara Francis ◽  
Eskil Skoglund ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Speed Of Sound ◽  
Turbine Blades ◽  
High Rate ◽  
Elastic Response ◽  
Surface Erosion ◽  
Wind Turbine Blades ◽  
Coating Materials ◽  
Erosion Testing ◽  
Rain Erosion

Under droplet impingement, surface leading edge protection (LEP) coating materials for wind turbine blades develop high-rate transient pressure build-up and a subsequent relaxation in a range of strain rates. The stress-strain coating LEP behavior at a working frequency range depends on the specific LEP and on the material and operational conditions, as described in this research in a previous work. Wear fatigue failure analysis, based on the Springer model, requires coating and substrate speed of sound measurements as constant input material parameters. It considers a linear elastic response of the polymer subjected to drop impact loads, but does not account for the frequency dependent viscoelastic effects for the materials involved. The model has been widely used and validated in the literature for different liquid impact erosion problems. In this work, it is shown the appropriate definition of the viscoelastic materials properties with ultrasonic techniques. It is broadly used for developing precise measurements of the speed of sound in thin coatings and laminates. It also allows accurately evaluating elastic moduli and assessing mechanical properties at the high frequencies of interest. In the current work, an investigation into various LEP coating application cases have been undertaken and related with the rain erosion durability factors due to suitable material impedance definition. The proposed numerical procedures to predict wear surface erosion have been evaluated in comparison with the rain erosion testing, in order to identify suitable coating and composite substrate combinations. LEP erosion performance at rain erosion testing (RET) technique is used widely in the wind industry as the key metric, in an effort to assess the response of the varying material and operational parameters involved.

Others' participation rate influences an individual's charitable behavior: Others' similarity as a moderator

2017 ◽  
Vol 45 (10) ◽  
pp. 1607-1618 ◽  
Author(s):  
Seung Yun Lee ◽  
Sunho Jung ◽  
Sangdo Oh ◽  
Seong Hoon Park
Keyword(s):  
Undergraduate Students ◽  
Participation Rate ◽  
High Rate ◽  
Charitable Behavior ◽  
High Participation ◽  
Negative Effect ◽  
The Impact ◽  
And Diffusion ◽  
High Participation Rate ◽  
Diffusion Of Responsibility

We proposed that a moderator, others' similarity, would determine the impact of high participation rates of others on an individual's charitable behavior, and aimed to show that this moderator would work through the diffusion of responsibility motive. Participants (N = 152 undergraduate students) completed measures of charitable behavior and diffusion of responsibility, after being assigned to 1 of 2 conditions where a set percentage of other students (manipulated as either similar undergraduate students or dissimilar graduate students) were stated to have already donated to a charitable campaign (high contribution condition = 70% participation, low contribution condition = 30% participation). Our results showed that the high participation rate of others increased an individual's charitable behavior when the others in question were similar to that individual, but not when the others were dissimilar. In addition, the high rate of participation by others increased the diffusion of responsibility motive when the others in question were dissimilar to that individual, leading to a negative effect on that individual's charitable behavior.

scholarly journals Peculiarities of Neurostimulation by Intense Nanosecond Pulsed Electric Fields: How to Avoid Firing in Peripheral Nerve Fibers

2021 ◽  
Vol 22 (13) ◽  
pp. 7051
Author(s):  
Vitalii Kim ◽  
Emily Gudvangen ◽  
Oleg Kondratiev ◽  
Luis Redondo ◽  
Shu Xiao ◽  
...  
Keyword(s):  
Side Effects ◽  
Electric Fields ◽  
Pulsed Electric Fields ◽  
Opposite Polarity ◽  
Nerve Fibers ◽  
High Rate ◽  
Excitation Threshold ◽  
Compound Action Potentials ◽  
Supramaximal Stimulation ◽  
The Impact

Intense pulsed electric fields (PEF) are a novel modality for the efficient and targeted ablation of tumors by electroporation. The major adverse side effects of PEF therapies are strong involuntary muscle contractions and pain. Nanosecond-range PEF (nsPEF) are less efficient at neurostimulation and can be employed to minimize such side effects. We quantified the impact of the electrode configuration, PEF strength (up to 20 kV/cm), repetition rate (up to 3 MHz), bi- and triphasic pulse shapes, and pulse duration (down to 10 ns) on eliciting compound action potentials (CAPs) in nerve fibers. The excitation thresholds for single unipolar but not bipolar stimuli followed the classic strength–duration dependence. The addition of the opposite polarity phase for nsPEF increased the excitation threshold, with symmetrical bipolar nsPEF being the least efficient. Stimulation by nsPEF bursts decreased the excitation threshold as a power function above a critical duty cycle of 0.1%. The threshold reduction was much weaker for symmetrical bipolar nsPEF. Supramaximal stimulation by high-rate nsPEF bursts elicited only a single CAP as long as the burst duration did not exceed the nerve refractory period. Such brief bursts of bipolar nsPEF could be the best choice to minimize neuromuscular stimulation in ablation therapies.

scholarly journals The High-Rate Sealed MRPC to Promote Pollutant Exchange in Gas Gaps: Status on the Development and Observations

2021 ◽  
Vol 11 (11) ◽  
pp. 4722
Author(s):  
Botan Wang ◽  
Xiaolong Chen ◽  
Yi Wang ◽  
Dong Han ◽  
Baohong Guo ◽  
...  
Keyword(s):  
Gas Flow ◽  
High Rate ◽  
Stable Operation ◽  
Beam Test ◽  
High Luminosity ◽  
Rate Test ◽  
3D Printed ◽  
Resistive Plate Chambers ◽  
The Impact ◽  
Current Behavior

This work reports the latest observations on the behavior of two Multigap Resistive Plate Chambers (MRPC) under wide high-luminosity exposures, which motivate the development and in-beam test of the sealed MRPC prototype assembled with low-resistive glass. The operation currently being monitored, together with previous simulation results, shows the impact of gas pollution caused by avalanches in gas gaps, and the necessity to shrink the gas-streaming volume. With the lateral edge of the detector sealed by a 3D-printed frame, a reduced gas-streaming volume of ~170 mL has been achieved for a direct gas flow to the active area. A high-rate test of the sealed MRPC prototype shows that, ensuring a 97% efficiency and 70 ps time resolution, the sealed design results in a stable operation current behavior at a counting rate of 3–5 kHz/cm2. The sealed MRPC will become a potential solution for future high luminosity applications.

scholarly journals The Impact of an Inactivated Hepatitis A Vaccine with One Dose in Brazil: A Retrospective Time-Series

Vaccines ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 407
Author(s):  
Ana Luiza Bierrenbach ◽  
Yoonyoung Choi ◽  
Paula de Mendonça Batista ◽  
Fernando Brandão Serra ◽  
Cintia Irene Parellada ◽  
...  
Keyword(s):  
Time Series ◽  
Time Series Analysis ◽  
Hepatitis A ◽  
National Level ◽  
Age Groups ◽  
High Rate ◽  
Series Analysis ◽  
Annual Reduction ◽  
The Impact ◽  
Vaccination Period

Background: In 2014, a recommended one-dose of inactivated hepatitis A vaccine was included in the Brazilian National Immunization Program targeting children 12–24 months. This decision addressed the low to intermediate endemicity status of hepatitis A across Brazil and the high rate of infection in children and adolescents between 5 and 19 years old. The aim of the study was to conduct a time-series analysis on hepatitis A incidence across age groups and to assess the hepatitis A distribution throughout Brazilian geographic regions. Methods: An interrupted time-series analysis was performed to assess hepatitis A incidence rates before (2010–2013) and after (2015–2018) hepatitis A vaccine program implementation. The time-series analysis was stratified by age groups while a secondary analysis examined geographic distribution of hepatitis A cases. Results: Overall incidence of hepatitis A decreased from 3.19/100.000 in the pre-vaccine period to 0.87/100.000 (p = 0.022) post-vaccine introduction. Incidence rate reduction was higher among children aged 1-4 years old, with an annual reduction of 67.6% in the post-vaccination period against a 7.7% annual reduction in the pre-vaccination period (p < 0.001). Between 2015 and 2018, the vaccination program prevented 14,468 hepatitis A cases. Conclusion: Our study highlighted the positive impact of a recommended one-dose inactivated hepatitis A vaccine for 1–4-years-old in controlling hepatitis A at national level.

scholarly journals Exploring the effectiveness of a COVID-19 contact tracing app using an agent-based model

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jonatan Almagor ◽  
Stefano Picascia
Keyword(s):  
High Rate ◽  
Contact Tracing ◽  
Agent Based Model ◽  
Agent Based ◽  
The Social ◽  
Behavioural Factors ◽  
The Impact ◽  
Different Levels ◽  
User Rate

AbstractA contact-tracing strategy has been deemed necessary to contain the spread of COVID-19 following the relaxation of lockdown measures. Using an agent-based model, we explore one of the technology-based strategies proposed, a contact-tracing smartphone app. The model simulates the spread of COVID-19 in a population of agents on an urban scale. Agents are heterogeneous in their characteristics and are linked in a multi-layered network representing the social structure—including households, friendships, employment and schools. We explore the interplay of various adoption rates of the contact-tracing app, different levels of testing capacity, and behavioural factors to assess the impact on the epidemic. Results suggest that a contact tracing app can contribute substantially to reducing infection rates in the population when accompanied by a sufficient testing capacity or when the testing policy prioritises symptomatic cases. As user rate increases, prevalence of infection decreases. With that, when symptomatic cases are not prioritised for testing, a high rate of app users can generate an extensive increase in the demand for testing, which, if not met with adequate supply, may render the app counterproductive. This points to the crucial role of an efficient testing policy and the necessity to upscale testing capacity.

Efficacy of a password-protected pill-dispensing device to enhance disposal of unused opioids after cancer surgery.

2021 ◽  
Vol 39 (28_suppl) ◽  
pp. 264-264
Author(s):  
Jacob Cogan ◽  
Melissa Kate Accordino ◽  
Melissa Parsons Beauchemin ◽  
Sophie Ulene ◽  
Elena B. Elkin ◽  
...  
Keyword(s):  
Pain Control ◽  
Cancer Surgery ◽  
High Rate ◽  
Smartphone App ◽  
Opioid Use ◽  
Structured Interviews ◽  
Health Crisis ◽  
Patient Reported ◽  
After Cancer ◽  
The Impact

264 Background: Opioid misuse is a public health crisis. Initial opioid exposures often occur post-operatively, and 10% of opioid-naïve patients who undergo cancer surgery subsequently become long-term opioid users. It has been shown that 70% of opioids prescribed post-operatively go unused, but only 9% of unused pills are disposed appropriately, which increases the risk of unintended use. We evaluated the impact of an inexpensive, password-protected dispensing device with mail return capacity on retrieval of unused pills after cancer surgery. Methods: Adult patients scheduled for major cancer-related surgery were eligible. Enrolled patients received opioid prescriptions in a password-protected, pill-dispensing device (Addinex) from a specialty pharmacy. The mechanical device links to a smartphone app, which provides passwords on a prescriber-defined schedule. Patients request a password when they are in pain, enter the password into the device and receive a pill if the prescribed time has elapsed. The smartphone app provides clinical guidance based on patient-reported pain levels, and suggests tapering strategies. Patients are instructed to return the device in a DEA-approved mailer when opioid use is no longer required for pain control. Unused pills are destroyed upon receipt. The primary objective was to determine the feasibility of device return, defined as > 50% of patients with device return. We also explored patterns of device use, patient reported outcomes, and device satisfaction via surveys and semi-structured interviews. Results: Between October, 2020 and April, 2021, 13 patients completed the study; 4 patients are currently enrolled. Among the initial 13 patients, 7 underwent abdominal hysterectomy, 4 underwent mastectomy and 2 underwent cutaneous tumor resections. The majority of these patients (n = 10, 77%) returned the device, and more than half (n = 7, 54%) returned the device within 6 weeks of surgery. Only a minority of patients (n = 5, 38%) used the device to obtain opioids; most (n = 8, 62%) used no opioids at home, and all of these patients returned the device and the unused pills. Of 11 patients who participated in semi-structured interviews, most (n = 7, 64%) said they felt safer having opioids in the device instead of a regular pill bottle. Among device users, the majority (n = 4, 80%) reported an overall positive experience. All non-users reported having no opioid requirement for pain control. Conclusions: Our early findings suggest that use of an inexpensive, password-protected, pill-dispensing device to assist with opioid dispensing and return is feasible, with a high rate of device and unused opioid return to the pharmacy. This strategy may be effective for reducing opioid diversion. Analyses and recruitment are ongoing to evaluate the benefits of reducing post-operative opioid consumption.

As-Built Geometry and Surface Finish Effects on Fatigue and Tensile Properties of Laser Fused Titanium 6Al-4V

2017 ◽  
Author(s):  
Onome Scott-Emuakpor ◽  
Tommy George ◽  
Emily Henry ◽  
Casey Holycross ◽  
Jeff Brown
Keyword(s):  
Tensile Properties ◽  
Surface Finish ◽  
Fatigue Behavior ◽  
Turbine Blades ◽  
Material Behavior ◽  
Small Scale ◽  
Internal Cooling ◽  
Roughness Effects ◽  
Form And Function ◽  
And Function

The as-built material behavior of additive manufactured (AM) Titanium (Ti) 6Al-4V is investigated in this study. A solution heat treated, aged, stress relieved, and hot isostatic pressed Laser Powder Bed Fusion (LPBF) AM process was used to manufacture the specimens of interest. The motivation behind this work is based on the ever-growing desire of aerospace system designers to use AM to fabricate components with novel geometries. Specifically, there is keen interest in AM components with complex internal cooling configurations such as turbine blades, nozzle vanes, and heat exchangers that can improve small scale propulsion performance. Though it is feasible to three-dimensionally print parts that meet the Fit portion of a part characteristic description and identification, the Form and Function portions have proven to be more difficult to conquer. This study addresses both the Form and Function characteristics of the LPBF AM process via the investigation of geometry variation and surface roughness effects pertaining to mechanical properties and fatigue behavior of Ti 6Al-4V. Results show that geometry variation may be the cause of increased vibration fatigue life uncertainty. Also, both fatigue and tensile properties show profound discrepancies associated with surface finish. As-built surface finish specimens have lower fatigue and ductility performance, but the results are more consistent than polished data.

scholarly journals Treatment of Anorexia Nervosa: The Importance of Disease Progression in the Prognosis

2017 ◽  
Vol 30 (7-8) ◽  
pp. 517
Author(s):  
Rodrigo Andrade ◽  
Manuel Gonçalves-Pinho ◽  
António Roma-Torres ◽  
Isabel Brandão
Keyword(s):  
Anorexia Nervosa ◽  
Dropout Rate ◽  
University Hospital ◽  
High Rate ◽  
Prognostic Features ◽  
Illness Duration ◽  
Intense Fear ◽  
Life Threatening ◽  
Fear Of Weight Gain ◽  
The Impact

Introduction: Anorexia nervosa is a severe, usually chronic, life-threatening disease of complex etiology characterized by food restriction, overestimation of the importance of body weight and image, intense fear of weight gain and distortion of body image. Anorexia nervosa is associated with high rates of mortality, suicide and decreased quality of life. Our aim is to present an anorexia nervosa treatment program offered in a major university hospital in Portugal, and to determine the impact of illness duration before admission on the outcome. Our hypothesis is that patients with greater disease longevity may have worse prognosis and poorer outcome.Material and Methods: The sample included data from case records of 169 patients seen consecutively and for the first time at Centro Hospitalar São João, between 2010 and 2015. We performed a retrospective observational study which included data collected at admission and from later follow-up years.Results: From the initially selected patients, 14.8% reached total remission, 16% accomplished partial remission and 14.2% ended up with exacerbation/stagnation of the disease. The dropout rate was of 55% throughout our study period. We found significant differences on outcome rates between distinct illness duration groups (p = 0.007).Discussion: There are several factors frequently associated with poor outcome for anorexia nervosa. The interpretation of outcome findings was limited by the high rate of dropout and lack of consistent definition criteria.Conclusion: Our results support the idea that illness duration has an important role on the outcome and prognostic features of these patients.

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