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PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0243841
Author(s):  
Joel D. Barnes ◽  
Michelle D. Guerrero

The Canadian Assessment of Physical Literacy (CAPL) is the first comprehensive protocol designed to assess a child’s level of physical literacy. Current approaches to analyzing CAPL-2 raw data are tedious, inefficient, and/or can lead to computation errors. In this paper we introduce the capl R package (open source), designed to compute and visualize CAPL-2 scores and interpretations from raw data. The capl package takes advantage of the R environment to provide users with a fast, efficient, and reliable approach to analyzing their CAPL-2 raw data and a “quiet” user experience, whereby “noisy” error messages are suppressed via validation. We begin by discussing several preparatory steps that are required prior to using the capl package. These steps include preparing, formatting, and importing CAPL-2 raw data. We then use demo data to show that computing the CAPL-2 scores and interpretations is as simple as executing one line of code. This one line of code uses the main function in the capl package (get_capl()) to compute 40 variables within a matter of seconds. Next, we showcase the helper functions that are called within the main function to compute individual variables and scores for each test element within the four domains as well as an overall physical literacy score. Finally, we show how to visualize CAPL-2 results using the ggplot2 R package.


2021 ◽  
Vol 143 (1) ◽  
Author(s):  
Xueliang Lu ◽  
Luis San Andrés ◽  
Bonjin Koo ◽  
Scott Tran

Abstract An integral squeeze film damper (ISFD) offers the advantages of a lower number of parts, a shorter axial span, a lighter weight, a split manufacturing, and high precision on its film clearance construction. An ISFD does not only add damping to reduce shaft vibration amplitudes and to enhance the stability of a rotor-bearing system but also can be used to tune a rotor-bearing system natural frequency, and thus increasing the operational safety margin between the running shaft speed and the system critical speed. In spite of the numerous commercial applications, the archival literature is scant as per the experimental quantification of force coefficients for ISFDs. This paper details the results of an experimental and analytical endeavor to quantify and to predict the dynamic force coefficients of an ISFD, hence bridging the gap between theory and practice. With an axial length of 76 mm, the test damper element has four arcuate film lands, 73 deg in arc extent at a diameter of 157 mm, and each with a clearance (c) equaling to 0.353 mm. As is customary, the damper has its axial ends sealed with end plates produced by a set of installed shims giving an axial gap (d) equal to 1.5c, 1.21c, and 0.8c. A baseline configuration, namely, open ends, is also tested without the end seals in place. In the test rig, the ISFD and its housing are flexibly mounted while the rotor is rigid and stationary (no spinning). The lubricant is an ISO VG46 oil supplied at a low pressure, 1 to 2 bar(g) and ∼47 °C inlet temperature, typical of compressor applications. The test procedure applies static loads on the ISFD and records the bearing static offset or eccentricity to verify the structure stiffness, and meanwhile, individual hydraulic shakers deliver dynamic loads along two orthogonal directions to produce motions over a set frequency range, 10 Hz to 160 Hz. The ISFD produces direct damping and inertia that increase with the journal static eccentricity albeit at a lower rate than predictions from a computational squeeze film flow model that includes lubricant compressibility. The end seals are effective in significantly raising the damping coefficient while reducing the oil through flow rate. The damper with the tightest sealed ends (d = 0.8c) shows nearly 20 times more damping that the open ends ISFD albeit also revealing a significant stiffness hardening (negative virtual mass) as the excitation frequency increases. On the contrary, the open ends ISFD and the sealed-ends configurations with gaps d = 1.21c and 1.5c produce a (positive) virtual mass that exceeds the test element physical mass and thus softens the test element direct dynamic stiffness. For the configurations with loose end seals (d = 1.21c or larger to open ends), the model predicts well the damping coefficients but under predicts the added masses by 50% or more. Note this virtual mass coefficient, largely ignored in practice, can make the test element either extremely stiff as with the sealed damper configuration with the smallest gap d = 0.8c, or very soft as with the ISFD with end seals gap = 1.21c or 1.5c. Hence, designers are cautioned not to pursue overly tight end sealed dampers as the mineral lubricant, nearly incompressible though always having a small amount of entrapped gas, may behave distinctly when confined to a squeezed film volume and having no adequate routes to escape or flow through.


2020 ◽  
Vol 1695 ◽  
pp. 012153
Author(s):  
S V Sedykh ◽  
S B Rybalka ◽  
E A Kulchenkov ◽  
A A Demidov ◽  
A Yu Drakin ◽  
...  

Author(s):  
Luis San Andrés ◽  
Xueliang Lu ◽  
Bonjin Koo ◽  
Scott Tran

Abstract An integral squeeze film damper (ISFD) offers the advantages of a lower number of parts, a shorter axial span, a lighter weight, a split manufacturing and high precision on its film clearance construction. An ISFD does not only add damping to reduce shaft vibration amplitudes and to enhance the stability of a rotor-bearing system but also can be used to tune a rotor-bearing system natural frequency, and thus increasing the operational safety margin between the running shaft speed and the system critical speed. In spite of the numerous commercial applications, the archival literature is scant as per the experimental quantification of force coefficients for ISFDs. This paper details the results of an experimental and analytical endeavor to quantify and to predict the dynamic force coefficients of an ISFD, hence bridging the gap between theory and practice. With an axial length of 76 mm, the test damper element has four arcuate film lands, 73° in arc extent at a diameter of 157 mm, and each with a clearance (c) equaling to 0.353 mm. As is customary, the damper has its axial ends sealed with end plates produced by a set of installed shims giving an axial gap (d) equal to 1.5c, 1.21c, and 0.8c. A baseline configuration, namely open ends, is also tested without the end seals in place. In the test rig, the ISFD and its housing are flexibly mounted while the rotor is rigid and stationary (no spinning). The lubricant is an ISO VG46 oil supplied at a low pressure, 1 to 2 bar(g) and ∼ 47 °C inlet temperature, typical of compressor applications. The test procedure applies static loads on the ISFD and records the bearing static offset or eccentricity to verify the structure stiffness, and meanwhile, individual hydraulic shakers deliver dynamic loads along two orthogonal directions to produce motions over a set frequency range, 10 Hz to 160 Hz. The ISFD produces direct damping and inertia that increase with the journal static eccentricity albeit at a lower rate than predictions from a computational squeeze film flow model that includes lubricant compressibility. The end seals are effective in significantly raising the damping coefficient while reducing the oil through flow rate. The damper with the tightest sealed ends (d = 0.8c) shows nearly 20 times more damping that the open ends ISFD albeit also revealing a significant stiffness hardening (negative virtual mass) as the excitation frequency increases. On the contrary, the open ends ISFD and the sealed ends configurations with gaps d = 1.21c and 1.5c produce a (positive) virtual mass that exceeds the test element physical mass and thus softens the test element direct dynamic stiffness. For the configurations with loose end seals (d = 1.21c or larger to open ends), the model predicts well the damping coefficients but under predicts the added masses by 50% or more. Note this virtual mass coefficient, largely ignored in practice, can make the test element either extremely stiff as with the sealed damper configuration with the smallest gap d = 0.8c, or very soft as with the ISFD with end seals gap = 1.21c or 1.5c. Hence, designers are cautioned not to pursue overly tight end sealed dampers as the mineral lubricant, nearly incompressible though always having a small amount of entrapped gas, may behave distinctly when confined to a squeezed film volume and having no adequate routes to escape or flow through.


2020 ◽  
Vol 14 (2) ◽  
pp. 6652-6662
Author(s):  
Anilkumar M. Hanchinal ◽  
V.V. Katti

Jet impingement is most effective and active method for cooling and heating of any surface or system. The ability of jet impingement is greatly influenced by nozzle configuration and other dimensional and non-dimensional parameters. Impinging coaxial swirl jet generates interesting flow filed on any test surface and influences both pressure and heat distribution on impinging surfaces. In present study, an experimental investigation is carried to analyze the effects of turbulent coaxial swirl jet on the pressure distribution (PC & PCO) on convex element. For better and acceptable results, the desirable parameters are identified from previous research works. The present experimental result highlights the independency of pressure coefficient (PC) for jet-Reynolds number (Re=70000 to 45000), effect of circumferential angle (θ) or inclination of test element, effect of jet exit to test element distance (Z/dh) and effect of confinement on PC & PCO pattern on a convex test element. The higher pressure coefficient value are obtained at lower Z/dh = 1 & at θ = 15° to 12°and significant drop in the values are seen with increase in the Z/dh & θ. At θ = 20° to 30° the value of PC & PCO reaches to negative magnitude. The use of confinement tube enhancementthe pressure distribution (PC & PCO) by 61% to 64% is seen for the same flow conditions.


Vibration ◽  
2020 ◽  
Vol 3 (1) ◽  
pp. 34-41
Author(s):  
Karim Sachedina ◽  
Thomas Lato ◽  
Atef Mohany ◽  
Marwan Hassan

Acoustic transmission loss is a common parameter utilized throughout several studies to evaluate the acoustic characteristics of a given test element. Transmission loss has been frequently referred to as a source independent parameter. However, this work presents evidence that the incident acoustic pressure amplitude does, in fact, have an effect on the measured transmission loss for some passive damping devices. The transmission loss was experimentally measured utilizing the two-source location method and the specimens tested include an expansion chamber, a quarter wave resonator, a Herschel–Quincke tube and various Helmholtz resonators. When varying the power supplied to the acoustic source, it was noted that all the devices exhibited nearly constant values of transmission loss, with the exception of the Helmholtz resonators. The Helmholtz resonators had a significant variance of transmission loss with respect to the acoustic source power. This decrease in performance is caused by the “jet-flow” phenomenon occurring at the Helmholtz resonator neck, which results in increased acoustic losses. The present work illustrates that the assumption of source independence, which is often made when using transmission loss to evaluate damping devices, must be taken with caution, as this assumption is case dependent and may be crucial when scaling experimental studies to an industrial setting.


2019 ◽  
Vol 7 (1) ◽  
pp. 618-625
Author(s):  
Ratna Devi Elangbam

Urticaria is the inflammation of the skin due to a reaction to allergens, which presents itself as swollen pale red bumps or plaques. Urticaria is a very common type of allergic reaction, which can be triggered by food, dust, medicine, irritants, etc. Though the causes may seem infinite, the trigger is specific to an individual. The scientific research method of observation was followed to collect qualitative and quantitative data. The experiment or test element was a single patient with Urticaria. The patient was monitored and data were collected for a year and a half. The case experiment considered two categories, namely: 1. reaction to meat and dairy products were identified and appropriate measures were designed to eliminate all oral intake of said factors and replace it with neutral restorative foods, i.e. a vegan diet. 2. Understanding the mental impact of the patient with regular bodily functions, stress and anxiety stimulants such as peer pressure, were identified and other alternative life-style adaptations were designed and introduced to eliminate or minimize urticaria causes. The method of dietary doses and anxiety stabilization were administered regularly to find a cure for one and a half years. Findings show a major factor that alleviated the effects of diet and anxiety and increased dependence on God by spending more time on learning from the Holy Bible. Gradual implementation of the remedies gradually decreased the outbreaks. The patient stopped medication (Antihistamine) and is on a better lifestyle. One could further study on moderate life-style and its significance to avoid extreme living both on positive and negative aspects of life. Discussions on other factors like situation, demographics, food, lifestyle, and others could be different from time to time and from one individual to another.  


2018 ◽  
Vol 9 (1) ◽  
pp. 5 ◽  
Author(s):  
Filiz Akkaya ◽  
Wolfgang Klos ◽  
Timm Schwämmle ◽  
Gregor Haffke ◽  
Hans-Christian Reuss

In the field of powertrain engineering, longstanding knowledge was gained for testing conventional vehicle powertrains. The hitherto used test strategies here were more focused on the subsystems of the powertrain than on the powertrain as an integrated system. Through the electrification of the powertrain, the topology and the range of functions have changed. This leads to new challenges for the validation and requires not only adjustments of the test strategies for electric vehicle powertrains but establish and develop integrative tests for the powertrain as an integrated system in order to meet the increased complexity. This paper presents a method to develop a holistic test strategy for a hybrid and electrical vehicle powertrain. In order to avoid misunderstandings of the used terms, it is necessary to create a standard understanding of them. Therefore, a nomenclature is defined and described. Furthermore, a definition of a holistic test strategy is provided. The focus of this present study is on the powertrain and not on its single subsystems. Subsequently, the four steps of the method are introduced and the current results are presented. Finally, a new developed test element within the holistic test strategy is introduced. The findings of this study support the integrative testing for powertrains.


2016 ◽  
Vol 51 (7) ◽  
pp. 533-539 ◽  
Author(s):  
Adam C. Raikes ◽  
Sydney Y. Schaefer

Context: The long-term effects of concussion on brain function during cognitive tasks are not fully understood and neuroimaging findings are equivocal. Some images show hyperactivation of prefrontal brain regions in previously concussed individuals relative to controls, suggesting increased cognitive resource allocation. Others show prefrontal hypoactivation and hyperactivation in other regions as a presumed compensatory mechanism. Given the relationship between sympathetic arousal and neural activation, physiologic measures of arousal, such as electrodermal activity, may provide additional insight into the brain's functional changes in those with a history of concussion. Objective: To quantify differences in electrodermal activity during a commonly used standardized neurocognitive assessment between individuals with or without a history of concussion. Design: Descriptive laboratory study. Setting: Research laboratory. Patients or Other Participants: Seven asymptomatic individuals with a self-reported history of physician-diagnosed, sport-related concussion (number of previous concussions = 1.43 ± 0.53; time since most recent concussion = 0.75 to 6 years, median = 3 years) and 10 individuals without a history of concussion participated in this study. Main Outcome Measure(s): All participants wore bilateral wrist electrodermal activity sensors during the Standardized Assessment of Concussion. We measured normalized phasic (reactive) electrodermal activity during each test element (orientation, immediate recall, concentration, delayed recall). Results: A significant group-by-test element interaction was present (P = .003). Individuals with a history of concussion had greater phasic activity during delayed recall (P < .001). Delayed-recall phasic activity was greater in both groups relative to the other elements. Conclusions: Delayed recall resulted in greater physiologic arousal in previously concussed individuals relative to healthy control participants, supporting previous neuroimaging findings of increased prefrontal cortex activity during memory tasks after concussion. Given similar task performance and arousal patterns across the test, our results suggest that previously concussed individuals incur additional cognitive demands in a short-delay recall task.


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