REVIEW | doi:10.20944/preprints201608.0074.v1
Subject: Social Sciences, Education Studies Keywords: reflection; healthcare education; umbrella review
Online: 8 August 2016 (10:40:19 CEST)
Reflection in healthcare education is an emergent topic with many studies and reviews being published. The purpose of the present review is to map the literature in this field by performing a systematic review of reviews (umbrella review) and to explore which definitions and models are currently in use, how reflection impacts on design, evaluation and assessment and future challenges. Nineteen reviews were identified that satisfied inclusion criteria. Emerging themes were: reflection is currently portrayed as self-reflection and critical reflection with the epistemology-of-practice notion not being as much as expected in tandem with the evidence-based-medicine paradigm modern science advocates. Reflective techniques were recognised in multiple settings (e.g. summative, formative, group vs individual etc.) and have been associated with learning but assessment remains a research topic with issues of validity, reliability and replicability. Future challenges involve the epistemology of reflection in healthcare education and how to practice and assess reflection without losing its theoretical background.
ARTICLE | doi:10.20944/preprints202203.0322.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: wave reflection; cardiovascular modelling; arterial hemodynamics
Online: 24 March 2022 (05:21:26 CET)
Arterial ageing is thought to cause a diastolic-to-systolic shift in the return time (RT) of backward waves to central arteries. However, current methods of estimating RT—inflection point, zero crossing, and foot methods—depend on a single waveform feature and produce systolic RT throughout life. We propose a novel centroid method that accounts for the entire backward pressure waveform and develop a ground truth RT (GTRT), which can be used in computational models to test the accuracy of RT estimation methods. Linear wave tracking was implemented in a one-dimensional systemic arterial tree model and GTRT was calculated as the amplitude-weighted mean RT of backward waves at the ascending aorta. Using a virtual cohort of 1200 patients, the centroid RT was closest to GTRT compared to the zero crossing, inflection point, and foot methods; mean differences (limits of agreement) were -8 (-47,30), vs -42 (-136,52), -78 (-305,149), and -197 (-379,-15) ms, respectively. The sensitivity of the methods to changes in RT was also assessed in ten sheep. A balloon catheter in the descending thoracic aorta was used to generate a backward-running pulse that arrived at the ascending aorta at different times during diastole or systole, allowing the “bulk” RT of the backward-running wave ensemble to be manipulated. Only the centroid method was sensitive to both diastolic and systolic changes in RT. We conclude that the accuracy and robustness of the centroid method make it most suitable for evaluating the diastolic-to-systolic shift in RT of backward waves with ageing.
ARTICLE | doi:10.20944/preprints202203.0230.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: cardiovascular modelling; arterial haemodynamics; wave reflection
Online: 16 March 2022 (10:05:44 CET)
The arterial network in healthy young adults is thought to be structured to minimise wave reflection in conduit arteries, producing an ascending aortic pressure waveform with three key features: early systolic peak, negative systolic augmentation, and diastolic hump. One-dimensional computer models have provided significant insights into arterial haemodynamics, but no previous models of the young adult have exhibited these three features. Since the latter was likely to be related to unrepresentative or non-optimised impedance properties of the model arterial networks, we developed a new ‘YoungAdult’ model that incorporated 1) a novel and more accurate empirical equation for approximating wave speeds, based on area and relative distance to elastic-muscular arterial transition points, 2) optimally-matched arterial junctions, and 3) an improved arterial network geometry that eliminated ‘within-segment’ taper (which causes wave reflection in conduit arteries) whilst establishing ‘impedance-preserving’ taper. These model properties led to wave reflection occurring predominantly at distal vascular beds, rather than in conduit arteries. The model predicted all three typical characteristics of an ascending aortic pressure waveform observed in young adults. When compared with non-invasively acquired pressure and velocity measurements (obtained via tonometry and Doppler ultrasound in 7 young adults), the model was also shown to reproduce the typical waveform morphology observed in the radial, brachial, carotid, temporal, femoral, and tibial arteries. The YoungAdult model provides support for the concept that the arterial tree impedance in healthy young adults is exquisitely optimised, and it provides an important baseline model for investigating cardiovascular changes in ageing and disease states.
ARTICLE | doi:10.20944/preprints201912.0314.v1
Subject: Behavioral Sciences, Other Keywords: self-reflection; adolescent; Smoking Cessation Program
Online: 24 December 2019 (09:41:29 CET)
The study aimed to understand the experiences of adolescent smokers who participated in a smoking cessation program based on self-reflection, and to develop the theoretical basis for constructing similar programs. The participants, ten students from middle and high schools located in cities G and S, were interviewed after the program ended. Data were collected from August to November 2019 and analyzed using a phenomenological approach to understand participant experiences in depth. The analysis revealed five major themes: ‘Uniqueness of the Program,’ ‘Perception of Smoking Cessation,’ ‘Positive Reflection on Life,’ ‘Understanding Others,’ and ‘A Search for Hope and Vision in Life.’ The findings revealed that the smoking cessation program facilitated the development of self-identity and vision, which may indirectly strengthen the motivation for adolescent smokers to quit smoking. These findings suggest the need for a life-changing smoking cessation program that enhances self-concept and self-esteem. Moreover, it highlights the importance of follow-up research to ensure effectiveness, and the need to develop programs with creative content.
ARTICLE | doi:10.20944/preprints201701.0123.v1
Subject: Mathematics & Computer Science, Computational Mathematics Keywords: Regular polyhedra, reflection group, fundamental region, invariant mapping
Online: 26 January 2017 (10:35:59 CET)
A fast algorithm is established to transform points of the unit sphere into fundamental region symmetrically. With the resulting algorithm, a flexible form of invariant mappings is achieved to generate aesthetic patterns with symmetries of the regular polyhedra. This method avoids the order restriction of symmetry groups, which can be similarly extended to treat regular polytopes in n-dimensional space for n>=4.
ARTICLE | doi:10.20944/preprints201808.0151.v1
Subject: Social Sciences, Education Studies Keywords: reflective learning, assessment, self-reflection, self-regulation, physics education
Online: 7 August 2018 (23:43:05 CEST)
This paper addresses the development of knowledge and assessment-centered learning approaches within a reflective learning framework in a first year physics class in a university faculty. The quality of students’ reflections was scored using a Self-reporting Reflective Learning Appraisal Questionnaire at the end of each learning approach. The results showed the differences between the approaches based on reflections on the learning control through self-knowledge, by connecting experience and knowledge, as well as through self-reflection and self-regulation. Assessment-centered activities fundamentally help students identify aspects of their attitudes towards, as well as regulate, their sustainability learning education.
ARTICLE | doi:10.20944/preprints201708.0028.v1
Subject: Physical Sciences, Condensed Matter Physics Keywords: crystal growth; calcite; microfluidic; nanoconfinement; reflection interference contrast microscopy.
Online: 8 August 2017 (08:09:11 CEST)
Slow growth of calcite in confinement is abundant in Nature and man made materials. There is ample evidence that such confined growth may create forces that fracture solids. The thermodynamic limits are well known but since confined crystal growth is transport limited and difficult to control in experiment we have almost no information on the mechanisms or limits of these processes. We present a novel approach to in situ study of confined crystal growth using microfluidics for accurate control of the saturation state of the fluid and interferometric measurement of the topography of the growing confined crystal surface. We observe and explain the diffusion limited confined growth structures observed and can measure the crystal "floating" on a fluid film of 10-40~nm thickness due to the disjoining pressure. We find that there are two end member behaviours: smooth or intermittent growth in the contact region, the latter being faster than the former.
ARTICLE | doi:10.20944/preprints201705.0221.v1
Subject: Physical Sciences, Optics Keywords: ultra-low anti-reflection coating; ellipsometer; optical admittance method
Online: 31 May 2017 (11:50:18 CEST)
An ultra-low anti-reflection optical coating on both surfaces of a plastic cover slip was studied for use in confocal image measurement. The optical reflectance at a wavelength of 632.8 nm was less than 0.1% when the coated sample was placed in a liquid having a refractive index of 1.34 close to the aqueous solution of the biomaterial. The high- and low-index coating films, Substance-2 (PrTiO3) and silicon dioxide (SiO2), were measured by an ellipsometer to determine their optical refraction indices and extinction coefficients. Theoretically, when the two layer thicknesses are designed using the optical admittance diagram of the cover slip to approach the equivalent index of 1.34, a reflectance of 1.6×10-5% in the liquid could be obtained. Experimentally, the reflectance of the sample deposited on the two faces of the cover slip was 4.223±0.145% as measured in the air; and 0.050±0.002% as measured by a He-Ne laser in the liquid.
ARTICLE | doi:10.20944/preprints202011.0669.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: antenna; digital beamforming; reflection; frequency modulated continuous wave; target echo
Online: 26 November 2020 (11:20:08 CET)
In this paper, a high-performance antenna array system model is presented to analyze moving-object-skin-returns and track them in the presence of stationary objects using frequency modulated continuous wave (FMCW). The main features of the paper are bonding the aspects of antenna array and electromagnetic (EM) wave multi-skin-return modeling and simulation (M&S) with the aspects of algorithm and measurement/tracking system architecture. The M&S aspect models both phase and amplitude of the signal waveform from a transmitter to the signal processing in a receiver. In the algorithm aspect, a novel scheme for FMCW signal processing is introduced by combining time- and frequency-domain methods, including a vector moving target indication filter and a vector direct current canceller in time-domain, and a constant false alarm rate detector and a mono-pulse digital beamforming angle tracker in frequency-domain. In addition, unlike previous designs of using M×N fast Fourier transform (FFT) for an M×N array, only four FFTs are used, which tremendously saves time and space in hardware. With the presented model, the detection of the moving-target-skin-return in stationary objects under a noisy environment is feasible. Therefore, to track long range and high-speed objects, the proposed technique is promising. Using a scenario having 1) a target with 17 dBm2 radar cross section (RCS) at about 40 km range with 5.93 Mach speed and 11.6 dB post processing signal to noise ratio, and 2) a strong stationary clutter with 37 dBm2 RCS located at the proximity of the target, it demonstrates that the root-mean-square errors of range, angle and Doppler measurements are about 26 meters, 0.68 degree and 1100 Hz, respectively.
ARTICLE | doi:10.20944/preprints201907.0353.v1
Subject: Behavioral Sciences, Other Keywords: organic food; sustainable consumption; visualization; personal shopping data; reflection; feedback
Online: 31 July 2019 (11:11:50 CEST)
Although food retailers have embraced organic certified food products as a way to reduce their environmental loading, organic sales only make up a small proportion of total sales worldwide. Most consumers have positive attitudes towards organic food, but attitudes are not reflected in behaviour. This article addresses consumers’ attitude-behaviour gap regarding their purchase organic food and reports on how visualization of personal shopping data may encourage them to buy more organic food. Through the design of the visualization tool, the EcoPanel, and through an empirical study of its use, we provide evidence on the potential of the tool to promote sustainable food shopping practices. Sixty-five users tested the EcoPanel for five months and interviews were made with ten of these. The test users increased their purchase of organic food with 23%. The informants used the EcoPanel to reflect on their shopping behaviour and to increase their organic shopping. We conclude that the visualization of food purchases stimulates critical reflection and the formation of new food shopping practices. This implies that food retailers may increase sales of organic food through using a visualization tool available for their customers. In this way these retailers may decrease their environmental impact.
ARTICLE | doi:10.20944/preprints202208.0472.v1
Subject: Physical Sciences, Optics Keywords: geometrical optics; speed of light; reflection of light; modified Michelson interferometer
Online: 29 August 2022 (07:38:59 CEST)
The Sun is a frame at relative rest in which the light from Sun travels at the emitted speed c, and the Earth travels with the revolving speed v. The reflection of light as a mechanical phenomenon applies to the modified Michelson interferometer employed by Miller in his experiments with light from Sun. Unlike the Tomaschek experiments, which employ light from stars, the fringe shifts in the Miller experiments are predictable. This study derives the light speeds from the Sun entering the interferometer from 6 am to 6 pm and the corresponding fringe shifts confirming that Miller's observed fringe shifts are proof of the Earth's motion in the Sun's frame at relative rest and the Universe.
ARTICLE | doi:10.20944/preprints202106.0217.v1
Subject: Engineering, Automotive Engineering Keywords: solar collection; solid structure; heat absorption analysis; collection heat analysis; reflection spectrum
Online: 8 June 2021 (12:06:13 CEST)
A solid structure, such as a road, building wall or envelop, used as a solar collector is considered an effective and new way to use renewable energy. This paper focused on the temperature characteristics of four structures exposed to sunshine: asphalt, red brick, composite cement and concrete road slab. Furthermore, the collected heat based on a hydraulic system was investigated experimentally. For the four structure slabs, their temperature differences are due to solar radiation absorption varied greatly by the material’s heat absorptance and color. Through the test, asphalt slab attained the highest temperature and had the weakest reflection among the structures. Compared with the others, the temperature of the asphalt slab was greater by 8.1%, 14.9% and 16.4% than the brick, composite cement and concrete, respectively. The reflection intensity growth ratio was defined and indicates the growth potential for absorbing radiation in the solid slab surface. From the experiments, it was concluded that a suitable selection of road materials can greatly improve the thermal absorption, conduction and penetration into the solid slab. The collected heat capability was approximately 250 W/m2 to 350 W/m2 in the natural summer condition. A black coating or a surface modification can collect more heat, reaching greater than 250 W/m2. The solar collecting heat efficiency with a surface configuration of the road slab can reach above 30% in the summer time.
ARTICLE | doi:10.20944/preprints202001.0061.v1
Subject: Engineering, Civil Engineering Keywords: coastal seawall; impermeable; bimodal seas; reflection coefficient; bimodality; wave steepness; swell percentages
Online: 8 January 2020 (04:24:42 CET)
Understanding of reflection characteristics of coastal seawalls is crucial for design. Wave reflection can cause difficulties to small vessel manoeuvring at the harbour entrance and constitute damaging scouring at the toe of coastal structures. Previous studies have considered reflection characteristics of coastal seawalls under wind-generated random waves without paying attention to the effects of wave bimodality created by the presence of swell waves. The present study focuses on the influence of random wave bimodality on reflective characteristics of coastal seawalls. More than eight hundred experimental tests have been conducted to examine the reflection performance of impermeable sloping seawalls under bimodal waves. Reflection coefficients were computed from each test. Analysis of results suggests that both unimodal and bimodal waves give similar reflection characteristics. However, the reflection coefficient in bimodal sea states seems to be more prolonged than in the unimodal sea states. It was found that the reflection coefficient of coastal seawalls is strongly influenced by the seawall slope, the wave steepness, relative water depth, and the surf similarity parameters. A new empirical reflection equation to describe the influence of wave bimodality on the reflection characteristics of coastal seawalls has been formulated based on this study.
REVIEW | doi:10.20944/preprints201805.0096.v1
Subject: Engineering, Other Keywords: metamaterials; aviation noise; aeroacoustics; noise absorption; noise reflection; noise trapping; acoustic cloaking
Online: 4 May 2018 (15:05:21 CEST)
Metamaterials, man-made composites scaled smaller than the wavelength, have demonstrated a huge potential in their applications in acoustics, opening up for sub--wavelength acoustic absorbers, acoustic invisibility, perfect acoustic mirrors and acoustic lenses for hyper focusing, acoustic illusions and enabling new degrees of freedom in the control of the acoustic field. The zero, or even negative, refractive sound index of metamaterials offers possibilities in control of the acoustic pattern and sound at sub--wavelength scales. Despite the tremendous growth of the research on acoustic metamaterials during the last decade, the potential of metamaterial-based technologies in aeronautics is still not fully explored and its utilization is still in its infancy. Thus the principal concepts mentioned above could very well provide means to develop devices that would allow the mitigation of the impact of the civil aviation noise on the community. This paper gives a review of the state of the art of the most relevant works on acoustic metamaterials, analyzing them against their potential applicability in aeronautics, and in this process identifying possible implementation areas and interesting metabehaviors. It also identifies some technical challenges and possible future directions for research with the goal of unveiling the potential of metamaterials technologies in aeronautics.
ARTICLE | doi:10.20944/preprints202010.0335.v1
Subject: Mathematics & Computer Science, Artificial Intelligence & Robotics Keywords: Object perception; Reflection symmetry; Saliency Symmetry Model; Isotropic symmetry operator; Multi-scale implementation
Online: 15 October 2020 (16:32:18 CEST)
This paper presents an optimized feature-centered reflection symmetry axis detection and localization framework for object perception. The proposed framework is formed to obtain an improved reflection symmetry axis based on the salient symmetry feature. It starts with a refined Multi-scale Saliency Symmetry Model (MSSM), which is realized by applying isotropic symmetry operator on salient points in scale-space rather than all pixels. In each scale, salient points are initially extracted as local extremal from an image, and they are further refined by a multi-scale implementation for generating salient symmetry feature maps. A Symmetric Transformation Matrix is then computed using the optimal feature matching pairs, which can be explicitly used as an abstract representation of the constraint regions of symmetry objects in an image to optimize the performance of the potential symmetry axis detection. The framework has been investigated experimentally both on the classical dataset from a symmetry detection challenge and the latest dataset. It has shown that the framework can get a better or comparative result and also can be further adapted into terminated human--computer equipment for reflection symmetry object perception and tracking.
ARTICLE | doi:10.20944/preprints202008.0345.v1
Subject: Physical Sciences, Acoustics Keywords: surface water runoff; acoustic sensor array; reflected sound wave; reflection from rough surfaces
Online: 15 August 2020 (09:31:37 CEST)
Irrigation is a useful crop enhancement procedure up to the point where free surface water appears. Thereafter, water can begin to flow into waterways, leaching nutrients and giving rise to environmental damage, as well as being a waste of a precious resource. The current work addresses the problem of measuring free water on the surface of agricultural soils by a real-time acoustic remote sensing method. Directional acoustic transmitter and receiver arrays are used to define a ‘footprint’ on the ground from which changes in reflectance are sensed. These arrays are mounted on a moving irrigator. Chirp signals are used to provide along-path resolution and to ensure robustness against unwanted acoustic background noise from farm machinery and the irrigator. Field measurements have been conducted above a well-defined ‘quadrat’ with controlled and measured water content, and also with the instrument mounted on an operational irrigator. A structured light camera mounted above the footprint is used to validate surface water fraction. It is found that the areal fraction of free water on the soil surface can be reliably estimated from changes in the amplitude of the reflected sound waves. The mechanism giving rise to the observed acoustic reflectivity changes is discussed and a model is developed which agrees with normalized intensity observations with a coefficient of determination R2 between 0.65 and 0.83. The rms error between model predictions and observations is comparable to the rms variation of the measurements, indicating that there is insignificant error due to the choice of model.
REVIEW | doi:10.20944/preprints202010.0438.v1
Subject: Materials Science, Biomaterials Keywords: conversion efficiency; GaAs substrate; light absorption; nano-grating structures; reflection loss; simulation; solar cells
Online: 21 October 2020 (13:28:28 CEST)
At present, the world is now passing a very far different time than normal situation due to the COVID-19 pandemic crisis. The global life-style and human civilization is currently progressing with down-stream that affecting almost every sectors necessary for human civilizations except the current environmental situation. To control the COVID-19 spreading, most of the countries are following lockdown process that reduces human mobility, thus reducing the CO2 emission to the environment. Though the COVID-19 pandemic is a blessing for the present environment, however, the post-COVID world will face a massive thrust of energy and only conventional energy resources may not be enough to mitigate the energy demands. Solar power generation technology mainly the photovoltaic (PV) systems and their advancement can be the leading possibilities to minimize the gap between the power demand and generation. It is now time to think how we can improve the PV power generation in future and the post-COVID world. In this encyclopaedia communication, we report on Nano-technological approach to improve the conversion efficiency of GaAs solar cells. We have designed and optimized several types of nano-structured assemblies that can be implemented to reduce the front surface incident light reflection losses thus can assist to improve the conversion efficiency of GaAs solar cells.
ARTICLE | doi:10.20944/preprints201810.0263.v1
Subject: Engineering, Industrial & Manufacturing Engineering Keywords: large coaxial probe; thin planar materials; low-loss materials; relative permittivity; reflection coefficient; calibration
Online: 12 October 2018 (08:19:52 CEST)
This paper focuses on the non-destructive dielectric measurement for low-loss planar materials with a thickness of less than 3 mm using a large coaxial probe with an outer diameter of 48 mm. The aperture probe calibration procedure required only to make a measurement of the half-space air and three offset shorts. The reflection coefficient for the thin material is measured using a Keysight E5071C network analyzer from 0.3 MHz to 650 MHz and then converted to a relative dielectric constant and tangent loss via closed form capacitance model and lift-off calibration process. Measurement error of dielectric constant, Δεr is less than 2.5 % from 1 MHz to 400 MHz and the resolution of loss tangent, tan δ measurement is capable of achieving 3×10-3.
ARTICLE | doi:10.20944/preprints201610.0118.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: tissue-like phantoms; dual-modal imaging; fluorescence lifetime (FLT); FLT imaging (FLIM); diffusion reflection
Online: 27 October 2016 (11:52:21 CEST)
Tissue-like phantoms are widely used as a model for mimicking the optical properties of live tissue. This paper presents the results of a diffusion reflection method as well as fluorescence lifetime imaging microscopy measurements of fluorescein-conjugated gold nanorods in solution as well as inserted in solid tissue-imitating phantoms. A lack of consistency between the fluorescence lifetime results of the solutions and the phantoms raises a question about the ability of tissue-like phantoms to maintain the optical properties of inserted contrast agents.
ARTICLE | doi:10.20944/preprints202011.0740.v1
Subject: Chemistry, Analytical Chemistry Keywords: detonation nanodiamonds; photoacoustic IR spectroscopy; diffuse-reflectance IR spectroscopy; attenuated total internal reflection IR spectroscopy
Online: 30 November 2020 (16:12:52 CET)
The qualitative analysis of nanodiamonds by FTIR spectrometry as photoacoustic (PAS), diffuse-reflectance (DRIFT), and attenuated total reflection (ATR) modalities was evaluated for rapid and nondestructive analysis and comparison of nanodiamonds. The spectra reproducibility and signal-gathering depth was compared. The assignment of characteristic bands showed that only six groups of bands were present in spectra of all the modalities with appropriate sensitivity: 1760 (C=O stretch, isolated carboxyl groups); 1640–1632 (H–O–H bend, liquid water); 1400–1370 (non-carboxyl C–O–H in-plane bend and CH2 deformation); 1103 (non-carboxyl C–O stretch); 1060 (in-plane C–H bend, non-aromatic hydrocarbons and carbohydrates); and 940 cm–1 (out-of-plane carboxyl C–O–H bend). DRIFT provides the maximum number of bands and is capable of measuring hydrogen-bonded bands and CHX groups. ATR provides the good sensitivity for water and C–H/C–C bands in the range 2000–400 cm–1. PAS-FTIR reveals less bands than DRIFT but more intense bands than ATR-FTIR and shows the maximum sensitivity for absorption bands that do not appear in ATR-IR spectra and are expedient for supporting either DRIFT or PAS along with depth-profiling. Thus, all three modalities are required for full characterization of nanodiamonds surface functional groups.
TECHNICAL NOTE | doi:10.20944/preprints201906.0136.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: Active reflection coefficients; realised gain; multi-port antennas; U-slotted microstrip patch; quadrifilar helical antennas
Online: 14 June 2019 (15:07:34 CEST)
In this paper, precise examination of multi-port antennas with large mutual coupling between the ports is studied. For this purpose, some vital parameters such as active reflection coefficients and realised gain are emphasized. The main motivation of this research is the ignorance of this issue in several recently published papers. Hence, corrections and criticisms to some recently reported results are presented. At first, a microstrip patch consisting of two inverted U-slots is re-examined, which has been proposed in a recently published paper for wideband applications. However, the authors did not present satisfactory results to indicate the performance of the proposed structure. In reverse, some important parameters such as the antenna gain appear to be incorrectly reported. In this paper, the characteristics of the antenna are compared with a simple 50 Ω microstrip line excited by two probes, indicating no significant differences. In the remainder of this paper, some corrections are provided on two examples of wide-beam circularly polarised multi-fed antennas for satellite applications. The first example is the multi-fed spiral antennas with folded arms, which have been proposed as the widebeam antennas at 435 MHz. It is indicated that the antenna height should be increased for better performance. The second example is the quadrifilar square helical antennas with folded arms, which have been proposed as the widebeam antennas for 435 MHz with minor responses at 145 MHz. Some corrections are presented on the previously reported minor responses at 145 MHz.
ARTICLE | doi:10.20944/preprints201810.0647.v1
Subject: Mathematics & Computer Science, Artificial Intelligence & Robotics Keywords: electromyography; hand movement; health monitoring; maximum entropy reflection coefficients; classification algorithms; machine learning; feature selection
Online: 29 October 2018 (04:01:22 CET)
Classification of electromyographic signals has a wide range of applications, from clinical diagnosis of different muscular diseases to biomedical engineering, where their use as input control of prosthetic devices has become a hot topic of research. Challenge of classifying this signals relies on the accuracy of the proposed algorithm and the possibility of its implementation on hardware. This paper consider the problem of electromyography signal classification, solved with the proposed signal processing and feature extraction stages, with focus lying on the signal model and time domain characteristics for better classification accuracy. The proposal considers a simple preprocessing technique that produces signals suitable for feature extraction, and the Burg reflection coefficients to form learning and classification patterns. These coefficients yield a competitive classification rate compared to used time domain features. Sometimes, the feature extraction from electromyographic signals showed that procedure can omit less useful traits for machine learning models. Using feature selection algorithms provides a higher classification performance with as fewer traits as possible. Algorithms achieved a high classification rate up to 100% with low pattern dimensionality, with other kinds of uncorrelated attributes for hand movement identification.
ARTICLE | doi:10.20944/preprints202204.0303.v1
Subject: Arts & Humanities, Other Keywords: Blogging; intercultural competence; international learning outcomes; reflective writing; reflection; text analysis; text mining; psycholinguistics; linguistic markers
Online: 29 April 2022 (13:07:15 CEST)
This study combines insights from psycholinguistics and text analysis to identify linguistic markers of intercultural competence (ICC) in student blogs about intercultural experiences. By combining holistic ICC frameworks with a more analytical approach at text and word level, we were able to demonstrate that blogs with a high perceived level of ICC contain significantly more I-words, more insights words and less quantifiers. These markers of ICC constitute concrete cues for teachers when assessing reflective writing assignments and allow them to pinpoint concrete areas for improvement in their feedback and interaction with students.
ARTICLE | doi:10.20944/preprints201805.0271.v2
Subject: Engineering, Civil Engineering Keywords: building integrated photovoltaics; annual daylight simulation; reflection; RADIANCE; photon mapping; BSDF; HDR; image processing; feature detection
Online: 31 July 2018 (08:34:37 CEST)
With the increasing adoption of building integrated photovoltaics (BIPV), concerns arise about potential glare. While recommended criteria to assess glare exist, it is challenging to apply these in the spatial and temporal domains and communicate the complex data to planning authorities and clients. This paper presents a new computational workflow using annual daylight simulation, material modelling using bi-directional scattering distribution functions (BSDFs) and image-based postprocessing to obtain 3-dimensional renderings of cumulative annual irradiance and glare duration on the built environment. The annual daylight simulation considers relevant sun positions in high temporal resolution (15-minute timesteps) and measured BSDFs to model different PV materials. The postprocessing includes a relative irradiance visualisation comparing the impact of a proposed PV proportional to a reference material. It also includes a new spatio-temporal workflow to assess the glare duration based on recommended thresholds. This workflow is demonstrated with a case study of a proposed PV roof for a church, assessing the glare potential of two different PV materials. The visualisations indicate glare durations well below the thresholds with satinated PVs, and in noncritical zones outside observer positions with standard PVs. Thus the proposed PV roof does not cause any disturbing glare.
ARTICLE | doi:10.20944/preprints201906.0298.v1
Subject: Behavioral Sciences, Applied Psychology Keywords: rumination; psychological detachment; perseverative cognition; work reflection; vitality; burnout; thriving; work engagement; employee well-being; mental health
Online: 28 June 2019 (12:09:30 CEST)
In the literature on occupational stress and recovery from work several facets of thinking about work in off-job time have been conceptualized. However, research on the focal concepts is currently rather disintegrated. In this study we take a closer look at the five most established concepts, namely (1) psychological detachment, (2) affective rumination, (3) problem-solving pondering, (4) positive work reflection, and (5) negative work reflection. More specifically, we scrutinized (1) whether the five facets of work-related rumination are empirically distinct, (2) whether they yield differential associations with different facets of employee well-being (burnout, work engagement, thriving, satisfaction with life, and flourishing), and (3) to what extent the five facets can be distinguished from and relate to conceptually similar constructs, such as irritation, worry, and neuroticism. We applied structural equation modeling techniques to cross-sectional survey data from 474 employees. Our results provide evidence that (1) the five facets of work-related rumination are highly related, yet empirically distinct, (2) that each facet contributes uniquely to explain variance in certain aspects of employee well-being, and (3) that they are distinct from related concepts, albeit there is a high overlap between (lower levels of) psychological detachment and cognitive irritation. Our study contributes to clarify the structure of work-related rumination and extends the nomological network around different types of thinking about work in off-job time and employee well-being.
COMMUNICATION | doi:10.20944/preprints202104.0447.v1
Subject: Physical Sciences, Acoustics Keywords: optics; resolution; superresolution; Ernst Abbe; structured illumination; non-linear; image scanning microscopy; total internal reflection; MINFLUX; localization microscopy
Online: 16 April 2021 (14:45:48 CEST)
This article presents answers to the questions on superresolution and structured illumination microscopy as raised in the editorial of a recent publication [K. Prakash et al. arXiv, 2102.13649, 2021]. The answers are based on my personal views on superresolution in light microscopy, supported by reasoning. Discussed are the definition of superresolution, Abbe’s resolution limit and the classification of superresolution methods into non-linear-, prior-knowledge- and near-field-based superresolution. A further focus is put on capabilities and technical aspects of present and future structured illumination microscopy (SIM) methods.
ARTICLE | doi:10.20944/preprints202204.0061.v2
Subject: Physical Sciences, Optics Keywords: geometrical optics; speed of light; emission of light; propagation of light; reflection of light; Michelson-Morley experiment; modified Michelson interferometer
Online: 27 April 2022 (08:51:06 CEST)
Emission, propagation, and reflection of light as mechanical phenomena in inertial frames are based on the behavior of balls at the limit when their mass is zero. The kinematics of massless balls is like that of balls with mass. Light as a wave or particle is a massless entity. Therefore, it is natural to apply the kinematics of the massless balls to light. Consequently, the kinematics of light depends on its kinetics of electromagnetic nature and its kinematics of mechanical nature in its interactions of emission and reflection with the matter. The study of the physics phenomena in the frame at absolute rest includes those in the inertial frames. Considering this and applying the emission, propagation, and reflection of light as mechanical phenomena in the vacuum of the frame at absolute rest, this study derives formulas for the speed of the wavefront of a ray of light reflected by a fixed and moving mirror when the light comes from a fixed and moving source. The derived formulas apply to the modified Michelson interferometer, employed independently by R. Tomaschek and D. C. Miller in their experiments.
ARTICLE | doi:10.20944/preprints202009.0032.v1
Subject: Physical Sciences, Optics Keywords: geometrical optics; reflection of light; speed of light; interference of light; Michelson interferometer; Michelson–Morley experiment; elastic collision ball wall
Online: 2 September 2020 (07:43:45 CEST)
Derivation of light paths in the Michelson interferometer is based on the hypothesis that the speed of light does not change after reflection by a mirror in motion. The Michelson-Morley experiment predicts a fringe shift of 0.40. The same fringe shift is predicted for a particular Michelson interferometer in which the beam splitter of the interferometer makes an angle of 45° with the direction of light from the source. Light behaves like a wave and also as a particle. Thus, it is reasonable to consider the reflection of light as a mechanical phenomenon. With this hypothesis, the speed of light changes after reflection, and the predicted fringe shift for the particular Michelson interferometer is zero which is in accordance with the result of the Michelson-Morley experiment. Apparently, light travels in any inertial frame as if this particular interferometer belongs to a fixed frame. The velocity of light is considered independent of the velocity of its source, which is in accordance with astronomers’ observations of the binary stars, and the experiment performed at CERN, Geneva, in 1964.
Subject: Physical Sciences, Acoustics Keywords: electromagnetic waves, microwave frequency range, biological medium, wave propagation, reflection, refraction, surface wave, creeping wave, multilayered biological medium, body area networks
Online: 5 May 2021 (12:13:48 CEST)
Propagation of electromagnetic (EM) waves inside and on the surface of the human body is the subject of active research in area of biomedical applications. This research area is the basis for wireless monitoring of biological object parameters and characteristics. Much attention has been paid to radio-frequency identification systems, which are intended for biomedical applications. Solutions to the following problems are crucial to achieve the stated goals in the area of wireless monitoring: EM wave propagation inside regular and multilayer biological media, through the interface between different media, and on-body surface wave propagation. The biological object monitoring is based on a consideration of the followingprocesses: a) propagation of the EM wave in a biological medium considered as the dielectric with a high dielectric permittivity and substantial conductivity; b) penetration of the EM wave through the biological medium–air interface (wave reflection and refraction); c) propagation of the EM wave in a multi-layer biological medium; d) propagation of the EM wave along the plane or curved surface of biological objects.
ARTICLE | doi:10.20944/preprints202001.0266.v1
Subject: Engineering, Civil Engineering Keywords: rubble-mound; zero-freeboard; porous-media; immersed-boundary; level-set; Smagorinsky subgrid scale model; wave reflection; wave transmission; wave overtopping; wave setup
Online: 23 January 2020 (14:43:47 CET)
A numerical study for the effect of crest width, breaking parameter and trunk permeability on hydrodynamics and flow behavior in the vicinity of rubble-mound, permeable, zero-freeboard breakwaters (ZFBs) is presented. The modified two dimensional Navier-Stokes equations for two-phase flows in porous media with a Smagorinsky model for the subgrid scale stresses were solved numerically. An immersed-boundary/level-set method was used. The numerical model was validated for the cases of wave propagation over a submerged impermeable trapezoidal bar and over a low-crested permeable breakwater. Five cases of breakwaters were examined, and the main results are: (a) The size of the crest width, B, does not notably affect the wave reflection, vorticity and currents in the seaward region of ZFBs, while wave transmission, currents in the leeward side, and mean overtopping discharge, all decrease with increasing B. A non-monotonic behavior of the wave setup is also observed. (b) As the breaking parameter decreases, wave reflection, transmission, currents, mean overtopping discharge, and wave setup decrease. This observation is also verified by relevant empirical formulas. (c) As the ZFB trunk permeability decreases, an increase of the wave reflection, currents, wave setup, and a decrease of wave transmission and mean overtopping discharge is observed.