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1
Barányi, I., Á. Czifra und Gabor Kalácska. „Height-independent topographic parameters of worn surfaces“. International Journal Sustainable Construction & Design 2, Nr. 1 (06.11.2011): 35–40. http://dx.doi.org/10.21825/scad.v2i1.20433.
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Surface microtopography plays a dual role in the course of friction and wear processes. It affectsthe contact and temperature conditions, and it undergoes significant changes in accordance with the wearmechanism. Fractal dimension (Df), root mean square gradient (Sdq), surface area ratio (Sdr) and surfacekurtosis (Sku) parameters of microtopographies provides opportunities for understanding more deeply thewear processes independently from the amplitude of the roughness. Wear experiments and surfaceroughness measurements before and after wear were performed. Investigations extended to wear in thecourse of the non-lubricated ferrodo-steel material pairs, and lubricated camshaft-bushing pairs.
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Mofjeld, Harold O., Frank I. González, Vasily V. Titov, Angie J. Venturato und Jean C. Newman. „Effects of Tides on Maximum Tsunami Wave Heights: Probability Distributions*“. Journal of Atmospheric and Oceanic Technology 24, Nr. 1 (01.01.2007): 117–23. http://dx.doi.org/10.1175/jtech1955.1.
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Abstract A theoretical study was carried out to understand how the probability distribution for maximum wave heights (ηm) during tsunamis depends on the initial tsunami amplitude (A) and the tides. It was assumed that the total wave height is the linear sum of the tides and tsunami time series in which the latter is decaying exponentially in amplitude with an e-folding time of 2.0 days, based on the behavior of observed Pacific-wide tsunamis. Direct computations were made to determine the statistics of maximum height for a suite of different arrival times and initial tsunami amplitudes. Using predicted tides for 1992 when the lunar nodal f factors were near unity during the present National Tidal Datum Epoch 1983–2001, the results show that when A is small compared with the tidal range the probability density function (PDF) of the difference ηm − A is closely confined in height near mean higher high water (MHHW). The ηm − A PDF spreads in height and its mean height ηo − A decreases, approaching the PDF of the tides and MSL, respectively, when A becomes large compared with the tidal range. A Gaussian form is found to be a close approximation to the ηm − A PDF over much of the amplitude range; associated parameters for 30 coastal stations along the U.S. West Coast, Alaska, and Hawaii are given in the paper. The formula should prove useful in probabilistic mapping of coastal tsunami flooding.
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Wang, Hong Cai, und Yang Wang. „The Height Amplitudes of Surface Roughness Based on Area-Direction Character and Relative Assessed Indexes“. Advanced Materials Research 482-484 (Februar 2012): 1150–54. http://dx.doi.org/10.4028/www.scientific.net/amr.482-484.1150.
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To study the relationship among the height amplitude of surface roughness , assessed area and assessed direction, the height amplitudes SRa, SRq, SRsk and SRku based on area-direction character are defined in the paper. And on the foundation of these parameters, relative assessed area indexes, assessed direction indexes and assessed total indexes are established. SRa, SRq, SRsk and SRku are the natural extension of 2D height amplitudes Ra, Rq, Rsk and Rku. They are different from 3D height amplitudes Sa, Sq, Ssk and Sku. They provide an evidence to study the quantitative relationship among surface roughness, assessed area and assessed direction. Relative assessed area indexes, assessed direction indexes and assessed total indexes can be used to assess the distribution situation of height amplitudes of surface roughness related to area, direction and entireness.
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Didenkulova, I. „Nonlinear long-wave deformation and runup in a basin of varying depth“. Nonlinear Processes in Geophysics 16, Nr. 1 (29.01.2009): 23–32. http://dx.doi.org/10.5194/npg-16-23-2009.
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Abstract. Nonlinear transformation and runup of long waves of finite amplitude in a basin of variable depth is analyzed in the framework of 1-D nonlinear shallow-water theory. The basin depth is slowly varied far offshore and joins a plane beach near the shore. A small-amplitude linear sinusoidal incident wave is assumed. The wave dynamics far offshore can be described with the use of asymptotic methods based on two parameters: bottom slope and wave amplitude. An analytical solution allows the calculation of increasing wave height, steepness and spectral amplitudes during wave propagation from the initial wave characteristics and bottom profile. Three special types of bottom profile (beach of constant slope, and convex and concave beach profiles) are considered in detail within this approach. The wave runup on a plane beach is described in the framework of the Carrier-Greenspan approach with initial data, which come from wave deformation in a basin of slowly varying depth. The dependence of the maximum runup height and the condition of a wave breaking are analyzed in relation to wave parameters in deep water.
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Gritsinskaya, V. L., V. P. Novikova und A. I. Khavkin. „Variability of the dynamics of somatometric parameters in schoolchildren with different nutritional status (longitudinal study)“. Voprosy praktičeskoj pediatrii 15, Nr. 5 (2020): 68–72. http://dx.doi.org/10.20953/1817-7646-2020-5-68-72.
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Objective. To identify specific features of pubertal growth spurt in adolescents depending on their nutritional status in prepuberty. Patients and methods. We analyzed the dynamics of height and weight in 645 children (331 boys and 314 girls) aged between 8 and 16 years. All study participants were divided into three groups depending on whether their weight and height at the age of 8 years were within the normal limits given in the ‘WHO Growth Reference 2007’: children with physical development; underweight children; and overweight children. Results. The dynamics of somatometric parameters during pubertal growth spurt varied between children with different nutritional status. Underweight boys demonstrated prolonged and low-amplitude pubertal growth pattern; in boys with normal physical development, the growth spurt was usually shorter and had high amplitude. In overweight boys, the pubertal growth spurt started with higher annual increase in height, had a more pronounced amplitude, and was shorter than in peers (р < 0.001 ÷ р < 0.05). Both underweight girls and girls with normal physical development demonstrated low-amplitude pubertal growth spurt lasting for two years. Overweight girls had two peaks of pubertal growth spurt, which usually started earlier than in other girls (р < 0.001 ÷ р < 0.01). Conclusion. Our findings can be used as a guide for predicting pubertal spurt in children during medical examinations, determining adequate physical activity in physical education classes at school and in sports sections. Key words: children, nutritional status, pubertal growth spurt
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Gaile, Liga. „Analysis of Dynamic Parameters of Observation Towers in Latvia“. Environment. Technology. Resources. Proceedings of the International Scientific and Practical Conference 2 (08.08.2015): 57. http://dx.doi.org/10.17770/etr2013vol2.847.
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The purpose of this research is to experimentally identify the performance of most of the light-weight observation towers open for public in Latvia. It analyzes the structure of towers, technical condition, dynamic parameters and dynamic response to human movement along the tower height. During the experiment there were measured and recorded the vibration accelerations of 18 observation towers’ upper platform. Further dynamic parameters were extracted using the spectral analysis. There was performed the sensitivity analysis to establish parameters that most influences the dynamic response amplitudes due to human movement. All experimentally obtained fundamental frequencies of the inspected towers are in the typical range of human walking frequencies. It is found that the main parameter that denotes the response level (acceleration amplitude) of the tower due to human movement is a tower self-weight.
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Noury, Ahmed Osman. „Normal neurophysiologic parameters of the sural nerve among adult healthy Sudanese population“. Journal of Neurology & Stroke 11, Nr. 1 (22.01.2021): 12–15. http://dx.doi.org/10.15406/jnsk.2021.11.00446.
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Background: Nerve conduction studies (NCSs) are of central importance for the assessment of peripheral nervous system disorders. They help in the diagnosis, extent distribution of neural lesion as well as the prognosis of a disease process. The aim of this study is to establish normative NCS reference data of the sural nerve in Sudanese population for our EMG electrodiagnostic center; and to survey the effects of age, gender, height, weight and temperature on conduction Parameters. Methods: The study was conducted in Elmagzoub Neuroscience Electrodiagnostic Centre; supported by the Faculty of Medicine, National Ribat University, Khartoum, Sudan. NCSs were performed in 210 sural nerves of 105 adult healthy Sudanese subjects using standardized techniques. Results: The Right sural nerve SNAP parameters in the whole subjects were set as (mean ±standard deviation) for onset latency. peak latency, amplitude and conduction velocity. The values were 2.73±0.42 ms, 3.32±0.46 ms, 8.39±3.49 uV and 52.05±8.47 m/s, respectively. The Left sural nerve SNAP parameters in the whole study group were 2.71±0.50 ms, 3.29 ±0.52 ms, 8.54±4.56 uV and 52.66 ±8.95, respectively. Conclusion: The sural sensory nerve conduction parameters compared favorably with the existing literature. Age showed a positive correlation with latencies, and negative correlation with amplitude and velocity. Gender has conspicuous effect on all sural nerve conduction parameters. Height showed an effect on latency and conduction velocity whereas BMI revealed a negative correlation with amplitude and conduction velocity of sural nerve.
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Kozlova, E. S. „Investigation of the influence of amplitude spiral zone plate parameters on produced energy backflow“. Computer Optics 43, Nr. 6 (Dezember 2019): 1093–97. http://dx.doi.org/10.18287/2412-6179-2019-43-6-1093-1097.
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Investigation of the influence of parameters of silver, aluminum, gold, and chromium spiral zone plates on the longitudinal component of Umov-Pointing vector in produced optical vortices by using the frequency-dependent finite-difference time-domain method is presented. It is shown that the aluminum spiral zone plate with a relief height of 50 nm gives an optical vortex with the smallest longitudinal component of Umov-Pointing vector on the optical axis. The gold spiral zone plate is the least effective for the formation of vortex beams with a reverse energy flow.
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Shpilka, N. N. „IMPROVING THE STABILITY TWO-LEVEL CAR HAULER“. ACADEMIC JOURNAL Series: Industrial Machine Building, Civil Engineering 1, Nr. 48 (27.03.2017): 8–18. http://dx.doi.org/10.26906/znp.2017.48.209.
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To improve the lateral stability of car hauler way you value optimal cargo location parameters, elastically mounted on a platform, developed a mathematical model of its motion. At the same time take into account fluctuations in cargo and car hauler. According to the simulation results revealed that the system for car «hauler – cargo» accounting for elastic properties leads to a significant decrease in the frequency and amplitude of the system vertical oscillations. Therefore, the presence of the cargo can be regarded as a dynamic passive damping (in the case of a correct choice and design of layout parameters). There is proposed to reduce the distance between the cargo and the upper platform by determination of maximum values of the cargo oscillations amplitudes. In turn, the reduction of the height of the platform reduces the height of the center of gravity of the system, improves the stability of car hauler.
Keywords: car hauler, dynamic processes, fluctuations, platform, stability.
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Chang, Shyang-Jye, und Jing Chen. „Design and Fabrication of the Large Thrust Force Piezoelectric Actuator“. Advances in Materials Science and Engineering 2013 (2013): 1–5. http://dx.doi.org/10.1155/2013/912587.
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This paper presents a novel piezoelectric actuator containing double pushers. By using finite element analysis software, this study simulated the vibration mode and amplitude of piezoelectric actuators. The Taguchi method was used to design the parameters of piezoelectric actuators including length, width, height, and electrodes setting. This paper also presents a discussion regarding the influence that the design parameters had on the actuator amplitudes. Based on optimal design parameters, a novel piezoelectric actuator containing double pushers is produced and some thrust tests are also carried out. From the experiment results, the piezoelectric actuator containing double pushers can provide a greater thrust force than that of traditional actuators containing a single pusher as the preload is greater. Comparing with the traditional actuators, the thrust force of new actuator can be increased by 48% with the double preload.
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Ambaum, Maarten H. P. „Unimodality of Wave Amplitude in the Northern Hemisphere“. Journal of the Atmospheric Sciences 65, Nr. 3 (01.03.2008): 1077–86. http://dx.doi.org/10.1175/2007jas2298.1.
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Abstract A novel statistic for local wave amplitude of the 500-hPa geopotential height field is introduced. The statistic uses a Hilbert transform to define a longitudinal wave envelope and dynamical latitude weighting to define the latitudes of interest. Here it is used to detect the existence, or otherwise, of multimodality in its distribution function. The empirical distribution function for the 1960–2000 period is close to a Weibull distribution with shape parameters between 2 and 3. There is substantial interdecadal variability but no apparent local multimodality or bimodality. The zonally averaged wave amplitude, akin to the more usual wave amplitude index, is close to being normally distributed. This is consistent with the central limit theorem, which applies to the construction of the wave amplitude index. For the period 1960–70 it is found that there is apparent bimodality in this index. However, the different amplitudes are realized at different longitudes, so there is no bimodality at any single longitude. As a corollary, it is found that many commonly used statistics to detect multimodality in atmospheric fields potentially satisfy the assumptions underlying the central limit theorem and therefore can only show approximately normal distributions. The author concludes that these techniques may therefore be suboptimal to detect any multimodality.
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Greenspan, S. L., A. Klibanski, J. W. Rowe und D. Elahi. „Age-related alterations in pulsatile secretion of TSH: role of dopaminergic regulation“. American Journal of Physiology-Endocrinology and Metabolism 260, Nr. 3 (01.03.1991): E486—E491. http://dx.doi.org/10.1152/ajpendo.1991.260.3.e486.
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To investigate the influence of aging on dopaminergic modulation of pulsatile thyrotropin (TSH) secretion, we examined changes in circulating TSH levels during the day and night, with and without a dopamine antagonist metoclopramide, in healthy young (20-35 yr old) and old (69-83 yr old) subjects, with the use of cluster analysis. Baseline thyroid function tests including serum thyroxine, 3,5,3'-triiodothyronine (T3), T3 resin uptake, and TSH and the response of TSH to thyrotropin-releasing hormone were within normal limits in young and old subjects, and antimicrosomal and anti-thyroglobulin antibodies were absent in all participants. Pulsatile TSH secretion was identified in all subjects, and as a group there were significant increases in nocturnal peak height (P less than 0.01), amplitude (P less than 0.01), and mean TSH (P less than 0.001). TSH pulse amplitude increased 160% (P less than 0.05) at night compared with day in the young but was unchanged at night in the old. After the administration of metoclopramide there was a significant increase in peak height (P less than 0.01), amplitude (P less than 0.01), and mean TSH (P less than 0.01). However, the effect of metoclopramide was different in young and old subjects. In the young, daytime administration of metoclopramide increased TSH pulse height (P less than 0.02) and mean TSH (P less than 0.05); pulse parameters remained unchanged at night. In comparison, in old subjects after metoclopramide, pulse parameters were unchanged during the day but pulse amplitude significantly (P less than 0.01) increased at night. TSH pulse frequency remained stable with age and was unaltered after metoclopramide.(ABSTRACT TRUNCATED AT 250 WORDS)
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Semenov, Ivan, und Marina Chernigovskaya. „MATH SIMULATION OF MASS TRANSFER FROM VIBRATING SURFACE“. Scientific Papers Collection of the Angarsk State Technical University 2020, Nr. 1 (23.06.2020): 99–103. http://dx.doi.org/10.36629/2686-7788-2020-1-99-103.
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Results of modeling of mass transfer from a vibrating cone are given in the paper. Effect of such parameters as frequency, amplitude, height of the cone and diffusion coefficient on mass transfer rate is considered. An equation for calculation of mass transfer coefficient is obtained for similar processes.
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Ghizzoni, Lucia, Adima Lamborghini, Mariangela Ziveri, Cecilia Volta, Costantino Panza, Paolo Balestrazzi und Sergio Bernasconi. „Pulsatile growth hormone release in Turner's syndrome and short normal children“. Acta Endocrinologica 123, Nr. 3 (September 1990): 291–97. http://dx.doi.org/10.1530/acta.0.1230291.
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Abstract. To determine whether the quantitative and qualitative aspects of GH secretion in girls with Turner's syndrome are similar to those of short-normal children we studied the 24-h GH secretion of 10 patients with Turner's syndrome and 9 short-normal children with comparable auxological features. GH profiles, obtained by 30-min sampling, were analysed by the Pulsar programme. The pulsatile GH release over the 24 h in Turner's syndrome was similar to that in normal children. However, when the GH release over the 12 day and night hours were separately analysed, only normal children showed a night-time increase in the sum of peak amplitudes. Moreover, patients with Turner's syndrome had significantly decreased number and frequency of peaks in the night-time compared with short children. In shortnormal children but not in Turner's syndrome, height velocity was related to the 24-h integrated concentration of GH, area under the curve over zero-line and over baseline, sum of peak areas, and amplitudes. Night-time GH area over zero-line and over baseline, mean peak amplitude, height, area, sum of peak areas, and amplitudes were positively correlated with height velocity in short children, whereas in Turner's syndrome height velocity was related to daytime parameters only. In conclusion, girls with Turner's syndrome have a discrete pattern of pulsatile GH release. However, the relation of GH secretion to growth, in these patients, is uncertain.
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Araujo Frias, Yanca, Osmar Gabriel Trigo Marques de Oliveira, João Victor Tino Dellaqua, Evandro Pereira Prado, Paulo Renato Matos Lopes, Ronaldo Cintra Lima, Cosme Damião Cruz und Rafael Simões Tomaz. „Plant stand failures effect in genetic parameters estimation procedure in Eucalyptus sp.“ International Journal for Innovation Education and Research 8, Nr. 3 (01.03.2020): 264–76. http://dx.doi.org/10.31686/ijier.vol8.iss3.2227.
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The objective of this work was to verify the influence of the percentage of failures in a forest genetics experiment in the estimation of genetic parameters. The study consisted in the evaluation of two experiments of full‑sib families under randomized complete block design with three replicates conducted in the state of Minas Gerais, Brazil. The experiment I was evaluated in January 2002, with approximately 60 months of age. The experiment II was evaluated in January 2003, with 45 months of age. In both experiments, the evaluations consisted of the measurement of the diameter at breast height and plant height. For all the investigated genetic parameters, an increase in the amplitude of the estimates was verified due to the increase in the number of experimental failures. Variances and negative heritabilities were detected, from 35% of failure, indicating that in such cases, this proportion of failure may be problematic to estimate genetic values, to estimate the gain with the selective process and for make decision.
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Wang, Xuexi, und Feng Lin. „Numerical analysis on heat transfer and flow resistance performances of a heat exchanger with novel perforated wavy fins“. Thermal Science, Nr. 00 (2021): 255. http://dx.doi.org/10.2298/tsci210309255w.
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In this paper, the experimental and numerical study of thermo-hydraulic characteristics of perforated wavy fin heat exchanger and unperforated wavy fin heat exchanger were conducted. Firstly, the two kinds of fins were studied under different air inlet velocity and constant inlet temperature. The results show that Nusselt number increases with Reynolds number and friction factor decreases with Reynolds number. Then, the performance of the two kinds of fins is numerically analyzed, and the simulation results are in good agreement with the experimental data. On this basis, the influence of different perforated fin parameters (fin height H, fin pitch s, wave amplitude wa, perforation number n, perforation diameter d) on the thermal performance of wavy fin heat exchanger is discussed. It is indicated that friction factor and Nusselt number increase with increasing aperture, wave amplitude, fin pitch and perforation number or decreasing fin height under constant Reynolds number condition. Finally, the performance evaluation of heat exchangers with different parameters is carried out to obtain the best performance heat exchanger parameters, which can provide a reference for the design of the new wavy fin heat exchanger.
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Sheremetov, R. T., und V. P. Galakhov. „Influence of morphometric parameters of river basins on taxonomic richness of flora (by the example of the Tom river basin).“ Bulletin of Nizhnevartovsk State University, Nr. 2 (20.06.2020): 76–89. http://dx.doi.org/10.36906/2311-4444/20-2/10.
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The article deals with methodological is-sues of studying the influence of morphometric parameters of model basins (size, nature of the river network, shape) of the Tom river on the taxonomic structure of flora. Taking into account significant differences in the morphometric of river basins, which determine the diversity of environmental conditions in the Tom river basin, 22 model basins were identified. Morphometric of model basins is deter-mined by 25 parameters characterizing the main sizes of basins (area, length, width, height, etc.), features of the river network (length and number of rivers, etc.), as well as various forms of river basins. The indicators of floristic wealth are accepted: the number of species, the number of genera and the number of model pool families. The author considers the conditionality of taxonomic diversity of flora by morphometric characteristics of basins for three levels-species, genus and family. Morphological parameters of model basins vary widely, which determines the diversity of plant habitats. However, the size, features of the river network and shape are not equivalent to the richness of the flora. Taxonomic richness at each level (species, genus and family) depends primarily on the morphometric of river basins. It is established that the altitude parameters are significant, especially the maximum height, the amplitude of the height or fall of the river, and the dependence is high (α = 0,05 df = 20). The nature of the river network and the shape of the basins for taxonomic richness are not essential. The most important morphometric features of basins by the number of taxa of different hierarchical ranks include the same set of parameters of the basin, primarily the height and their maximum values, the amplitude of fluctuations in the height or fall of the river. At the species level, the significance of other parameters is much lower. A similar relationship is obtained at the genus and family levels. This changes not only the proximity of the relationship with the change in taxonomic rank, but also the number of the most significant morphometric parameters. The article contains 10 Tables, 27 References.
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Vis-Star, N. C., H. E. de Swart und D. Calvete. „Patch behaviour and predictability properties of modelled finite-amplitude sand ridges on the inner shelf“. Nonlinear Processes in Geophysics 15, Nr. 6 (08.12.2008): 943–55. http://dx.doi.org/10.5194/npg-15-943-2008.
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Abstract. The long-term evolution of shoreface-connected sand ridges is investigated with a nonlinear spectral model which governs the dynamics of waves, currents, sediment transport and the bed level on the inner shelf. Wave variables are calculated with a shoaling-refraction model instead of using a parameterisation. The spectral model describes the time evolution of amplitudes of known eigenmodes of the linearised system. Bottom pattern formation occurs if the transverse bottom slope of the inner shelf, β, exceeds a critical value βc. For fixed model parameters the sensitivity of the properties of modelled sand ridges to changes in the number (N−1) of resolved subharmonics (of the initially fastest growing mode) is investigated. For any N the model shows the growth and subsequent saturation of the height of the sand ridges. The saturation time scale is several thousands of years, which suggests that observed sand ridges have not reached their saturated stage yet. The migration speed of the ridges and the average longshore spacing between successive crests in the saturated state differ from those in the initial state. Analysis of the potential energy balance of the ridges reveals that bed slope-induced sediment transport is crucial for the saturation process. In the transient stage the shoreface-connected ridges occur in patches. The overall characteristics of the bedforms (saturation time, final maximum height, average longshore spacing, migration speed) hardly vary with N. However, individual time series of modal amplitudes and bottom patterns strongly depend on N, thereby implying that the detailed evolution of sand ridges can only be predicted over a limited time interval. Additional experiments show that the critical bed slope βc increases with larger offshore angles of wave incidence, larger offshore wave heights and longer wave periods, and that the corresponding maximum height of the ridges decreases whilst the saturation time increases.
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Li, Wen, Lin Song Yan und De Yuan Zhang. „Ultrasonic Elliptical Vibration Turning Studty for Precision and Ultra-Precision Workpiece“. Advanced Materials Research 189-193 (Februar 2011): 3–8. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.3.
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Based on ultrasonic elliptical vibration cutting (UEVC) model, kinematical formulas of elliptical vibration cutting(EVC) is established, the paper presented relationship of vibration parameters effecting on surface roughness, machining accuracy and machining efficiency, revealed UEVC characteristics of high frequency and small amplitude are more conducive to improve surface roughness, advance EVC machining efficiency. Experiences of cutting the weak rigidity workpiece by the designed adjusting frequency elliptical transducer is proved that compared conventional turning, increasing vibration frequency and decreasing amplitude are result in improve surface roughness, and compared low frequency EVC, decrease amplitude are result in reduce the height of vibration ripples in cutting direction, and advance machining efficiency. So high frequency and small amplitude EVC is more conducive to precision machining and ultra-precision machining.
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Grubor, D. P., D. M. Šulić und V. Žigman. „Classification of X-ray solar flares regarding their effects on the lower ionosphere electron density profile“. Annales Geophysicae 26, Nr. 7 (18.06.2008): 1731–40. http://dx.doi.org/10.5194/angeo-26-1731-2008.
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Abstract. The classification of X-ray solar flares is performed regarding their effects on the Very Low Frequency (VLF) wave propagation along the Earth-ionosphere waveguide. The changes in propagation are detected from an observed VLF signal phase and amplitude perturbations, taking place during X-ray solar flares. All flare effects chosen for the analysis are recorded by the Absolute Phase and Amplitude Logger (AbsPal), during the summer months of 2004–2007, on the single trace, Skelton (54.72 N, 2.88 W) to Belgrade (44.85 N, 20.38 E) with a distance along the Great Circle Path (GCP) D≈2000 km in length. The observed VLF amplitude and phase perturbations are simulated by the computer program Long-Wavelength Propagation Capability (LWPC), using Wait's model of the lower ionosphere, as determined by two parameters: the sharpness (β in 1/km) and reflection height (H' in km). By varying the values of β and H' so as to match the observed amplitude and phase perturbations, the variation of the D-region electron density height profile Ne(z) was reconstructed, throughout flare duration. The procedure is illustrated as applied to a series of flares, from class C to M5 (5×10−5 W/m2 at 0.1–0.8 nm), each giving rise to a different time development of signal perturbation. The corresponding change in electron density from the unperturbed value at the unperturbed reflection height, i.e. Ne(74 km)=2.16×108 m−3 to the value induced by an M5 class flare, up to Ne(74 km)=4×1010 m−3 is obtained. The β parameter is found to range from 0.30–0.49 1/km and the reflection height H' to vary from 74–63 km. The changes in Ne(z) during the flares, within height range z=60 to 90 km are determined, as well.
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Shen, Yongjun, Xiaoran Wang, Shaopu Yang und Haijun Xing. „Parameters Optimization for a Kind of Dynamic Vibration Absorber with Negative Stiffness“. Mathematical Problems in Engineering 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/9624325.
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A new type of dynamic vibration absorber (DVA) with negative stiffness is studied in detail. At first, the analytical solution of the system is obtained based on the established differential motion equation. Three fixed points are found in the amplitude-frequency curves of the primary system. The design formulae for the optimum tuning ratio and optimum stiffness ratio of DVA are obtained by adjusting the three fixed points to the same height according to the fixed-point theory. Then, the optimum damping ratio is formulated by minimizing the maximum value of the amplitude-frequency curves according toH∞optimization principle. According to the characteristics of negative stiffness element, the optimum negative stiffness ratio is also established and it could still keep the system stable. In the end, the comparison between the analytical and the numerical solutions verifies the correctness of the analytical solution. The comparisons with three other traditional DVAs under the harmonic and random excitations show that the presented DVA performs better in vibration absorption. This result could provide theoretical basis for optimum parameters design of similar DVAs.
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Guillas, S., J. Rougier, A. Maute, A. D. Richmond und C. D. Linkletter. „Bayesian calibration of the Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIE-GCM)“. Geoscientific Model Development 2, Nr. 2 (28.09.2009): 137–44. http://dx.doi.org/10.5194/gmd-2-137-2009.
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Abstract. In this paper, we demonstrate a procedure for calibrating a complex computer simulation model having uncertain inputs and internal parameters, with application to the NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM). We compare simulated magnetic perturbations with observations at two ground locations for various combinations of calibration parameters. These calibration parameters are: the amplitude of the semidiurnal tidal perturbation in the height of a constant-pressure surface at the TIE-GCM lower boundary, the local time at which this maximises and the minimum night-time electron density. A fully Bayesian approach, that describes correlations in time and in the calibration input space is implemented. A Markov Chain Monte Carlo (MCMC) approach leads to potential optimal values for the amplitude and phase (within the limitations of the selected data and calibration parameters) but not for the minimum night-time electron density. The procedure can be extended to include additional data types and calibration parameters.
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Guillas, S., J. Rougier, A. Maute, A. D. Richmond und C. D. Linkletter. „Bayesian calibration of the Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIE-GCM)“. Geoscientific Model Development Discussions 2, Nr. 1 (12.05.2009): 485–506. http://dx.doi.org/10.5194/gmdd-2-485-2009.
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Abstract. In this paper, we demonstrate a procedure for calibrating a complex computer simulation model having uncertain inputs and internal parameters, with application to the NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM). We compare simulated magnetic perturbations with observations at two ground locations for various combinations of calibration parameters. These calibration parameters are: the amplitude of the semidiurnal tidal perturbation in the height of a constant-pressure surface at the TIE-GCM lower boundary, the local time at which this maximises and the minimum night-time electron density. A fully Bayesian approach, that describes correlations in time and in the calibration input space is implemented. A Markov Chain Monte Carlo (MCMC) approach leads to potential optimal values for the amplitude and phase (within the limitations of the selected data and calibration parameters) but not for the minimum night-time electron density. The procedure can be extended to include additional data types and calibration parameters.
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Jiang, Bin, Guang Lei Cao, Ming Hui Zhang, Shou Zheng Sun und Xuan Chi Liu. „Influence Characteristics of Tool Vibration and Wear on Machined Surface Topography in High-Speed Milling“. Materials Science Forum 800-801 (Juli 2014): 585–89. http://dx.doi.org/10.4028/www.scientific.net/msf.800-801.585.
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Existing research on machined surface topography, only consider its response to vibration or wear certain factors, both vibration and wear impact on machined surface topography exist ambiguity and uncertainty, it cannot solve the design conflicts of machined surface topography. For this, this paper analyzes blade installation error, tool wear, vibration and deformation to reveal effects of tip space trajectory, build a three-dimensional model of machined surface topography in simulation, extract its characteristic parameters, by simulation of different amplitudes and wear, found that axis amplitude is a key factor affecting surface residual height, flank wear affects contour distribution distance significantly, by specimen milling experiments, use vibration measuring instrument and ultra-depth microscopy to obtain vibration, wear characteristics and machined surface topography parameters under different cutting parameters, then use the gray system theory to get correlation analysis of the test data, results showed that the influence of tool wear on machined surface topography is prominent than tool vibration.
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Javadi, Hamid, Walid Jomaa, Damien Texier, Myriam Brochu und Philippe Bocher. „Surface Roughness Effects on the Fatigue Behavior of As-Machined Inconel718“. Solid State Phenomena 258 (Dezember 2016): 306–9. http://dx.doi.org/10.4028/www.scientific.net/ssp.258.306.
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Surface finish of machined components plays a key role in their life performance. The aim of this research is to investigate the effect of different roughness parameters on high cycle fatigue behavior of Inconel718. Rotating bending fatigue tests have been performed on Inconel718 specimens with various surface roughnesses produced by turning. Height and amplitude distribution roughness parameters were investigated. Statistical analyses show that a valley material component (Mr2), as one of the amplitude distribution parameters, is the most relevant parameter for the high cycle fatigue life of machined specimens. Observations conducted at the surface of broken specimens gage length, have shown the impact of surface roughness and residual stresses on the crack propagation mode. When the roughness increases, valleys were shown to be deeper and larger, leading to a higher Mr2 value and an increase of stress concentration.
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Jam, Jafar Eskandari, Milad Noorabadi und Nader Namdaran. „Nonlinear Free Vibration Analysis of Micro-beams Resting on Viscoelastic Foundation Based on the Modified Couple Stress Theory“. Archive of Mechanical Engineering 64, Nr. 2 (01.06.2017): 239–56. http://dx.doi.org/10.1515/meceng-2017-0015.
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AbstractIn this paper, nonlinear free vibration analysis of micro-beams resting on the viscoelastic foundation is investigated by the use of the modified couple stress theory, which is able to capture the size effects for structures in micron and sub-micron scales. To this aim, the gov-erning equation of motion and the boundary conditions are derived using the Euler–Bernoulli beam and the Hamilton’s principle. The Galerkin method is employed to solve the governing nonlinear differential equation and obtain the frequency-amplitude algebraic equation. Final-ly, the effects of different parameters, such as the mode number, aspect ratio of length to height, the normalized length scale parameter and foundation parameters on the natural fre-quency-amplitude curves of doubly simply supported beams are studied.
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Guo, Li Bin, Hai Cui, Bin Zhang und Zhi Hang Zhang. „Research on Statistical Parameters of 3-D Roughness for Micro Wire Electric Discharge Machining Surface“. Key Engineering Materials 572 (September 2013): 287–90. http://dx.doi.org/10.4028/www.scientific.net/kem.572.287.
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Amplitude parameters and functional parameters of three-dimensionalroughness are established by statistics geometry. Since micro wire electric discharge machining (MWEDM) surface approximately follows the Gauss distribution, its statistical characteristics are different from cutting processing surface. Characterization meaning between MWEDM surface and cutting processing surface is rather different. This study begins with shape parameters’ mathematics essence of surface height distribution of three-dimensionalroughness, analyzes their definite characterization meanings for MWEDM surface, deeply researches bearing ratio curve of MWEDM surface, reasonably ascertains its functional areas and finally establishes nine functional parameters where volume parameter is the main one.
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Fry, S. A. „The Damage Capacity of Cavitating Flow From Pulse Height Analysis“. Journal of Fluids Engineering 111, Nr. 4 (01.12.1989): 502–9. http://dx.doi.org/10.1115/1.3243675.
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Digital pulse amplitude acquisition systems are reviewed and an analogue pulse height analyser (PHA) is described. Cavitation experiments are reported in which pressure pulses in the liquid (water) are picked up by a flush mounted pressure transducer and measured using the PHA. Tests were carried out on two cavitation sources: a 60 deg symmetric wedge and a circular cylinder. Despite generating similar r.m.s. noise levels the wedge is 21 times as damaging as the circular cylinder at peak noise flow conditions (at V = 16 m/s). By imposing thresholds on the spectra parameters it had been possible to find a linear calibration beween noise and erosion applicable to both cavitation sources over a range of flow velocities. A good correlation between cavitation noise and erosion was found by simply measuring the number of pulses above a suitable threshold.
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Duan, Runze, Yifan Cao, Hongbin Duan, Liang Tian, Liting Tian, Cong Du, Liansheng Liu, Nan Rong und Tiansheng Li. „Effect of the inner-surface baffles on the tangential acoustic mode in the cylindrical combustor“. Open Physics 18, Nr. 1 (31.12.2020): 1215–22. http://dx.doi.org/10.1515/phys-2020-0187.
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Abstract The combustion instability in a propulsion system is a ubiquitous problem. The radial baffles usually installed on the injector faceplate eliminate the combustion instability (acoustic pressure oscillation) in the propulsion system. In this article, the longitudinal baffles are installed on the inner surface of the combustor wall to control the combustion instabilities. The first-order and second-order tangential modes are induced in the experiments. The effects of the parameters of the baffle on the acoustic pressure oscillation in the cylindrical combustor are investigated. The effect of the combustor nozzle on the tangential modes has been systematically investigated. It is concluded that the eigen-frequency and amplitude of the first-order tangential mode decline with the increase in the longitudinal baffle number and height. For the second-order tangential mode, the eigen-frequency and amplitude monotonically increase until a maximum value (four baffles), subsequently decrease with the increase in the baffle number and height. The combustor without the nozzle obtains a lower frequency than that with the nozzle, especially for the low baffle height in the combustor.
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Alhazmi, Hani, und Rasim Guldiken. „Contactless Liquid Height and Property Estimation Using Surface Acoustic Waves“. Acoustics 2, Nr. 2 (06.06.2020): 366–81. http://dx.doi.org/10.3390/acoustics2020021.
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The propagation of surface acoustic waves over a solid plate is highly influenced by the presence of liquid media on the surface. At the solid–liquid interface, a leaky Rayleigh wave radiates energy into the liquid, causing a signification attenuation of the surface acoustic wave amplitude. In this study, we take advantage of this spurious wave mode to predict the characteristics of the media, including the volume or height. In this study, the surface acoustic waves were generated on a thick 1018 steel surface via a 5 MHz transducer coupled through an angle beam wedge. A 3D-printed container was inserted on the propagation path. The pulse-echo time-domain responses of the signal were recorded at five different volumes (0, 400, 600, 1000, and 1800 µL). With the aid of parametric CAD analysis, both the position and distance of the entire traveling wave in the liquid layer were modeled and verified with experimental studies. The results indicated that the average drop in the reflected wave amplitude due to liquid loading is −62.5% compared to the empty container, with a percentage of error within 10% for all cases. The localized-time frequency components of the reflected wave were obtained via a Short-Time Fourier Transform technique. Up to 10% reduction (500 KHz) in the central frequency was observed due to the liquid volume increasing. The method discussed herein could be useful for many applications, where some of the liquid’s parameters or the ultrasonic wave behavior in the liquid need to be assessed.
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Boryczko, Adam, und Wojciech Rytlewski. „SURFACE IRREGULARITIES AS A COMPLEX SIGNAL OF TOOL REPRESENTATION TOGETHER WITH UNEVEN DISPLACEMENT IN RESPECT TO THE WORKPIECE“. Metrology and Measurement Systems 21, Nr. 1 (01.03.2014): 133–44. http://dx.doi.org/10.2478/mms-2014-0013.
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Abstract In a dynamic machining process, distortion in surface irregularity is a very complex phenomenon. Surface irregularities form a periodic representation of the tool profile with various kinds of disturbance in a broad range of changes in the height and length of the profile. To discern these irregularity disturbances, interactions of the tool in the form of changes perpendicular and parallel relative to the workpiece were analyzed and simulated. The individual kinds of displacement of the tool relative to the workpiece introduce distortions in the changes of height and length. These changes are weakly represented in standard height and length irregularity parameters and their discernment has been found through amplitude-frequency functions.
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Wang, Yan, Bin Lin, Yan Yu Ding, Zhi Qiang Fu, Xiao Feng Zhang und Ying Huai Dong. „Effect of Ultrasonic Vibration Assisted Grinding Process on Surface Topography and Properties of C/SiC Composite“. Key Engineering Materials 764 (Februar 2018): 210–18. http://dx.doi.org/10.4028/www.scientific.net/kem.764.210.
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This paper study on the influence of ultrasonic vibration assisted grinding (UAG) process on surface topography and properties of C/SiC composites. Through the surface quality experiments of common grinding (CG) and UAG, the height distribution parameters and function parameters are obtained and used to analyze the characteristics of the material surface topography. The relationship between grinding process and the composites surface quality is pointed out by experimental research. The orthogonal design is employed to optimize ultrasonic parameters and grinding parameters. The optimized condition is carried out to modify the surface quality. The results show that ultrasonic vibration has a great influence on height and surface bearing properties; the surface roughness is improved by the small vibration amplitude and low frequency. The grinding depth is the key factor on surface topography modification and the feed rate is the second. According to the research, an important technical support is carried out to improve the surface performance of C/SiC composites.
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Gao, Xinggong, Zeqin Liu und Wenyuan Zhao. „Study on the influence of float parameters on the efficiency of oscillating float wave power generation“. E3S Web of Conferences 206 (2020): 03027. http://dx.doi.org/10.1051/e3sconf/202020603027.
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The world’s environmental pollution is more and more serious, and the human society for the energy demand is more and more large, so o the research of clean new energy is very necessary. In this paper, flow-3D software is used to simulate and study the motion state, velocity, kinetic energy, wave force and amplitude of cone and cylinder floats under different masses with the same wave height, so as to obtain the influence of mass on wave absorption efficiency and output power of these two kinds of floats. The results show that :(1) when the wave height is 0.25m, the wave energy absorption efficiency of the cylindrical and conical float increases first and then decreases with the increase of mass. The absorption efficiency of the 6kg cone float is the best, which is 27.77%. (2) With the increase of mass, the output work of the conical float firstly increases and then decreases, and reaches its maximum value at 6kg, which is 1.27w.
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Setsuko, Suzuki, Ichiro Tamaki, Kiyoshi Ishida und Nobuhiro Tomaru. „Relationships between flowering phenology and female reproductive success in the Japanese tree species Magnolia stellata“. Botany 86, Nr. 3 (März 2008): 248–58. http://dx.doi.org/10.1139/b07-135.
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We have examined the earliness, duration, and amplitude of flowering genets in a Magnolia stellata (Sieb. et Zucc.) Maxim. population in relation to their size, environmental factors (temperature and light), and female reproductive success (ovule survival rate) over three consecutive years. Average flowering durations of individual flowers, genets, and the whole population in these 3 years were 10.2, 15.2, and 29.0 d, respectively. A bisexual phase (with both female and male phase flowers) in genets spanned 62.9% of the total flowering period, suggesting that geitonogamy can occur. The earliness, duration, and amplitude of flowering genets were all significantly correlated, indicating that genets flower early and long periods have high flowering amplitudes. The three parameters were also significantly correlated with the size of the genets (represented by the diameter at breast height of its thickest ramet) and relative photosynthetic photon flux density at the top of their crowns. Therefore, genets that are large and located in well-lit sites tend to have many flowers, and blossom both earlier and longer. Later-flowering genets have higher female reproductive success, probably because M. stellata is protogynous. Significantly positive correlation between flowering amplitude and female reproductive success suggests that large numbers of flowers increase the attractiveness of genets for pollinators, and this outweighs the negative effects of geitonogamy.
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Wang, Shu-qi, Ying Zhang, Yang-yang Xie, Gang Xu, Kun Liu und Yuan Zheng. „Hydrodynamic Analysis of Horizontal Axis Tidal Current Turbine under the Wave-Current Condition“. Journal of Marine Science and Engineering 8, Nr. 8 (26.07.2020): 562. http://dx.doi.org/10.3390/jmse8080562.
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To take advantage of the high tidal current velocity near the free surface, the horizontal axis turbine is installed, which inevitably causes hydrodynamic characteristics to effect the turbine by the waves. In this article, we established a numerical calculation method for the hydrodynamic load of a horizontal axis turbine under wave-current conditions. Based on the numerical calculation results, the hydrodynamic loads were decomposed and the influence rules of wave parameters and blade tip immersion depth on the hydrodynamic load were obtained. The study found the following: (1) the multi-frequency fluctuations based on the rotation frequency and incident wave frequency occurred in instantaneous values of the axial load coefficients and energy utilization ratios, and the fluctuation amplitude decreased with the increase of the blade tip immersion depth; (2) the fluctuation amplitude, according to rotation frequency, changed less with the increase of wave period and wave height, and was smaller according to wave frequency; (3) the fluctuation amplitude based on wave frequency increased linearly with the increase of wave height and wave period. The research results can provide the basis and reference for the design and engineering application of tidal current power station.
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Бородулин, Дмитрий, Dmitriy Borodulin, Татьяна Зорина, Tatyana Zorina, Виталий Иванец, Vitalij Ivanets, Екатерина Невская et al. „Key Operation Parameters of the Vibration Mixer in the Production of Flour Baking Mixes“. Food Processing: Techniques and Technology 49, Nr. 1 (26.06.2019): 77–83. http://dx.doi.org/10.21603/2074-9414-2019-1-77-84.
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Food is one of the major health-determining factors. Thus, any product should be of high quality and contain valuable substances. Therefore, the authors selected a flour baking mix with a high content of protein to determine the key operation parameters of the vibration mixer. There have been a lot of researches that feature flour baking mixes with the help of various mixers. The present research employed an original vibration mixer of continuous action with a method of “consecutive dilution”. The experiment determined the speed of vibrotransportation of the protein mix through the operating part of the device. The power consumption of the device, as well as the speed of the vibrotransportation of the baking mix, can affect the process of mixing. Therefore, the authors studied the mutual impact of the technological parameters of the mixer and the power consumption. The analysis helped to determine the effect of the key parameters on the speed of vibrotransportation of the flour baking mix. The speed υ increased with the increase in the oscillation frequency of the operating part f and the vibration amplitude A. A high amplitude and oscillation frequency proved to increase the value of power consumption of the vibromixer. Its key operation parameters were as follows: the amplitude of vibration A = 0.0035 m, the angle of vibration β = 45°, the height of the vibroboiling layer = 0.02 m, the diameter of perforation of the operating part of the device d = 0.007 m.
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Christiansen, Bo. „Bimodality of the Planetary-Scale Atmospheric Wave Amplitude Index“. Journal of the Atmospheric Sciences 62, Nr. 7 (01.07.2005): 2528–41. http://dx.doi.org/10.1175/jas3490.1.
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Abstract The evidence for multiple flow regimes in the planetary-scale atmospheric wave amplitude index (WAI) is studied using the 56 winters from the NCEP reanalysis data. The regimes are identified by bimodality in the probability density estimates. Both the probability density of the WAI alone and the probability density in the two-dimensional space spanned by the WAI and its temporal rate of change are examined. The latter procedure allows us to exploit the quasi stationarity of the regimes and increase the statistical significance. The statistical significance of bimodality in the probability densities is tested by a Monte Carlo approach using surrogate time series that preserve the full autocorrelation spectrum of the original WAI. By using a longer dataset and including the rate of change, some of the questions raised in previous studies about the robustness and statistical significance of the bimodality of the WAI are resolved. Statistically significant bimodality is found in the WAI based on the 500-hPa height. The probability density of the WAI shows considerable low-frequency variability on decadal scales. However, the bimodality is reproduced in all decadal subperiods although without statistical significance. The last decade has been dominated by a strong (disturbed) regime while a weak (zonal) regime dominates the previous decades. This recent change toward the disturbed regime is statistically significant. Imprints of the regimes are found at other tropospheric levels including the sea level. In particular, the regimes are found with statistical significance in the WAI based on the sea level pressure for the subperiod 1979–2003. Systematically varying the upper and lower boundaries of the latitudinal interval over which the geopotential height is averaged shows that the bimodality of the WAI is rather sensitive to these parameters, but also that statistically significant bimodality is found for a range of intervals with the lower boundary at 45°–50°N.
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Shepherd, M., und C. Fricke-Begemann. „Study of the tidal variations in mesospheric temperature at low and mid latitudes from WINDII and potassium lidar observations“. Annales Geophysicae 22, Nr. 5 (08.04.2004): 1513–28. http://dx.doi.org/10.5194/angeo-22-1513-2004.
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Abstract. Zonal mean daytime temperatures from the Wind Imaging Interferometer (WINDII) on the Upper Atmosphere Research Satellite (UARS) and nightly temperatures from a potassium (K) lidar are employed in the study of the tidal variations in mesospheric temperature at low and mid latitudes in the Northern Hemisphere. The analysis is applied to observations at 89km height for winter solstice, December to February (DJF), at 55° N, and for May and November at 28° N. The WINDII results are based on observations from 1991 to 1997. The K-lidar observations for DJF at Kühlungsborn (54° N) were from 1996–1999, while those for May and November at Tenerife 28° N were from 1999. To avoid possible effects from year-to-year variability in the temperatures observed, as well as differences due to instrument calibration and observation periods, the mean temperature field is removed from the respective data sets, assuming that only tidal and planetary scale perturbations remain in the temperature residuals. The latter are then binned in 0.5h periods and the individual data sets are fitted in a least-mean square sense to 12-h and 8-h harmonics, to infer semidiurnal and terdiurnal tidal parameters. Both the K-lidar and WINDII independently observed a strong semidiurnal tide in November, with amplitudes of 13K and 7.4K, respectively. Good agreement was also found in the tidal parameters derived from the two data sets for DJF and May. It was recognized that insufficient local time coverage of the two separate data sets could lead to an overestimation of the semidiurnal tidal amplitude. A combined ground-based/satellite data set with full diurnal local time coverage was created which was fitted to 24h+12h+8h harmonics and a novel method applied to account for possible differences between the daytime and nighttime means. The results still yielded a strong semidiurnal tide in November at 28° N with an amplitude of 8.8K which is twice the SD amplitude in May and DJF. The diurnal tidal parameters were practically the same at 28° N and 55° N, in November and DJF, respectively, with an amplitude of 6.5K and peaking at ~9h. The diurnal and semidiurnal amplitudes in May were about the same, 4K, and 4.6K, while the terdiurnal tide had the same amplitudes and phases in May and November at 28° N. Good agreement is found with other experimental data while models tend to underestimate the amplitudes. Key words. Atmospheric composition and structure (pressure, density and temperature) – Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides)
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Wennink, Johanna M. B., Henriette A. Delemarre-van de Waal, Rik Schoemaker, Gert Blaauw, Caro van den Braken und Joop Schoemaker. „Growth hormone secretion patterns in relation to LH and testosterone secretion throughout normal male puberty“. Acta Endocrinologica 123, Nr. 3 (September 1990): 263–70. http://dx.doi.org/10.1530/acta.0.1230263.
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Abstract. Pulsatile growth hormone secretion patterns were studied in relation to LH and testosterone release in 30 healthy prepubertal boys and 2 adult men. Plasma GH was measured every 10 min, plasma LH and testosterone every hour. Night-time GH secretion parameters were 2-3 times higher than daytime values. During daytime, mean GH level and the fraction of GH in pulses increased from Tanner stage G2 to G4 (p=0.01); during night-time these parameters increased as well (p≤0. 1) and decreased from stage G5 to adulthood (p=0.05). GH pulse number did not increase; the number of high-amplitude (>8 μg/l pulses, however, increased from stage G2 to G4 (p=0.05) during the day. Height velocity correlated with the number of high pulses during day and night (τ=0.39, p<0.003). From stage G2 to G4 significant correlations were observed between nocturnal testosterone levels and GH secretion parameters (τ=0.53-0.57), in contrast to nocturnal LH levels. It is concluded that during puberty 1. GH secretion increases as a result of an increased pulse amplitude; 2. there is no consistent correlation between GH and LH levels; 3. increasing nocturnal testosterone levels are correlated with the increasing GH secretion; therefore GnRH does not seem to influence GH secretion directly, but an indirect effect via testosterone is more conceivable, and 4. height velocity is correlated with the number of high GH pulses.
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Filho, Salvador Ávila, Júlia Spínola Ávila, Beata Mrugalska, Naiara Fonseca de Souza, Ana Paula Meira Gomes de Carvalho und Lhaís Rodrigues Gonçalves. „Decision Making in Health Management during Crisis: A Case Study Based on Epidemiological Curves of China and Italy against COVID-19“. International Journal of Environmental Research and Public Health 18, Nr. 15 (30.07.2021): 8078. http://dx.doi.org/10.3390/ijerph18158078.
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In December 2019, a new infectious respiratory disease called COVID-19 was identified in Wuhan, Hubei province, in China and quickly reached pandemic status in March 2020, in uncertain and frightening situation. The objective of this study was to analyze the epidemiological curves from the fight against COVID-19 in China and Italy, establishing parameters that can assist with the decisions of health-planning managers. This study was conducted using the principles of the grounded theory methodology and a practical method of comparison between the real and ideal curves, based on the contamination and death data by SARS-CoV-2 in China and Italy. For this purpose, we built graphs, including parameters, such as, among others, amplitude, height, saturation point, acceleration, lethality, event, risk, and efficiency. The results of our study showed that China exhibited amplitude and height of the active contamination and death curve 2 times smaller than those of Italy which exhibited several saturations. It was investigated that Italy presented a qualitative risk of 5–6, whereas for China it was 4. According to the parameters, China and Italy presented health management that was able to reduce the impact caused by the virus. The implementation of adequate health management with these practical tools can guide perception of the crisis critical levels, avoiding major disasters. We intend to continue to validate the method in the analysis of data from Brazil and the USA.
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Knobler, Sagi, Daniel Bar, Rotem Cohen und Dan Liberzon. „Wave Height Distributions and Rogue Waves in the Eastern Mediterranean“. Journal of Marine Science and Engineering 9, Nr. 6 (14.06.2021): 660. http://dx.doi.org/10.3390/jmse9060660.
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There is a lack of scientific knowledge about the physical sea characteristics of the eastern part of the Mediterranean Sea. The current work offers a comprehensive view of wave fields in southern Israel waters covering a period between January 2017 and June 2018. The analyzed data were collected by a meteorological buoy providing wind and waves parameters. As expected for this area, the strongest storm events occurred throughout October–April. In this paper, we analyze the buoy data following two main objectives—identifying the most appropriate statistical distribution model and examining wave data in search of rogue wave presence. The objectives were accomplished by comparing a number of models suitable for deep seawater waves. The Tayfun—Fedele 3rd order model showed the best agreement with the tail of the empirical wave heights distribution. Examination of different statistical thresholds for the identification of rogue waves resulted in the detection of 99 unique waves, all of relatively low height, except for one wave that reached 12.2 m in height which was detected during a powerful January 2018 storm. Characteristics of the detected rogue waves were examined, revealing the majority of them presenting crest to trough symmetry. This finding calls for a reevaluation of the crest amplitude being equal to or above 1.25 the significant wave height threshold which assumes rogue waves carry most of their energy in the crest.
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Tsurkan, Oleh, Ruslan Horbatiuk und Dmytro Prysiazhniuk. „PLANNING A MULTI-FACTOR EXPERIMENT FOR DETERMINING RATIONAL PARAMETERS OF THE VIBRATION MACHINE OPERATION“. Vibrations in engineering and technology, Nr. 2(97) (27.08.2020): 5–14. http://dx.doi.org/10.37128/2306-8744-2020-2-1.
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The approaches and methods of improving the quality and efficiency of agricultural machinery repair are of priority importance in Ukraine today. The tough competitive environment in the interstate and domestic market of technical services dictates its own terms. One of the promising research methods is the planning of an experiment in the optimization of multifactorial processes, such as vibration strengthening processing of agricultural machinery parts. The object of the research in this article was the technological process of finishing, cleaning and strengthening processing of parts of tillage machines with their surface plastic vibration deformation. The purpose of the work was to plan a multifactorial experiment for the theoretical determination of the compromise parameters of the operation of a vibration machine with an activator of the movement of the working medium for strengthening the treatment of the working bodies of tillage machines. The task of the work was to: analyze research and publications on the basics of probability theory, mathematical statistics, foundations of correlation, variance and regression analyzes, planning an optimal experiment; obtain the coefficients of complex equations of multiple regression of the 2nd order and plot the dependence of the consumed energy consumption by the developed installation on the amplitude of oscillations of the working chamber, the amplitude of oscillations of the activator, angular velocity of the drive shaft of the working chamber, angular velocity of the drive shaft of the activator, processing time; the height of microroughnesses from the vibration amplitude of the working chamber, the vibration amplitude of the activator, the angular velocity of the drive shaft of the working chamber, the angular velocity of the drive shaft of the activator, the processing time; surface hardness on the vibration amplitude of the working chamber, vibration amplitude of the activator, angular velocity of the drive shaft of the working chamber, angular velocity of the drive shaft of the activator, processing time; based on the results of the research and testing of the developed installation on the basis of the constructed response surfaces of the processes under study, to determine the rational technological parameters of its operation, the compromise value of which can be obtained by the Cramer method in the mathematical environment "Mathcad 15". The research methodology was based on mathematical statistics, correlation, variance and regression analyzes, planning an optimal experiment. In scientific work, based on the results of a multifactorial experiment, a mathematical model was obtained in the form of multiple second-order regression, which adequately describes the technological process under study. Compromise technological parameters of the investigated process were obtained, which are: the amplitude of oscillations of the working chamber - 2-4 mm; the vibration amplitude of the activator is 1.5-2.5 mm; the angular speed of the drive shaft of the working chamber - 115-120 rad/s; the angular speed of the drive shaft of the activator 130-145 rad/s; processing time - 80 min.
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Scharinger, Mathias, Philip J. Monahan und William J. Idsardi. „Asymmetries in the Processing of Vowel Height“. Journal of Speech, Language, and Hearing Research 55, Nr. 3 (Juni 2012): 903–18. http://dx.doi.org/10.1044/1092-4388(2011/11-0065).
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Purpose Speech perception can be described as the transformation of continuous acoustic information into discrete memory representations. Therefore, research on neural representations of speech sounds is particularly important for a better understanding of this transformation. Speech perception models make specific assumptions regarding the representation of mid vowels (e.g., [ɛ]) that are articulated with a neutral position in regard to height. One hypothesis is that their representation is less specific than the representation of vowels with a more specific position (e.g., [æ]). Method In a magnetoencephalography study, we tested the underspecification of mid vowel in American English. Using a mismatch negativity (MMN) paradigm, mid and low lax vowels ([ɛ]/[æ]), and high and low lax vowels ([ i ]/[æ]), were opposed, and M100/N1 dipole source parameters as well as MMN latency and amplitude were examined. Results Larger MMNs occurred when the mid vowel [ɛ] was a deviant to the standard [æ], a result consistent with less specific representations for mid vowels. MMNs of equal magnitude were elicited in the high–low comparison, consistent with more specific representations for both high and low vowels. M100 dipole locations support early vowel categorization on the basis of linguistically relevant acoustic–phonetic features. Conclusion We take our results to reflect an abstract long-term representation of vowels that do not include redundant specifications at very early stages of processing the speech signal. Moreover, the dipole locations indicate extraction of distinctive features and their mapping onto representationally faithful cortical locations (i.e., a feature map).
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Zerefos, C. S., E. Gerasopoulos, I. Tsagouri, B. Psiloglou, A. Belehaki, T. Herekakis, A. Bais et al. „Evidence of gravity waves into the atmosphere during the March 2006 total solar eclipse“. Atmospheric Chemistry and Physics Discussions 7, Nr. 3 (31.05.2007): 7603–24. http://dx.doi.org/10.5194/acpd-7-7603-2007.
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Abstract. This study aims at testing the hypothesis according to which the movement of the moon's shadow sweeping the ozone layer at supersonic speed during a solar eclipse creates gravity waves in the atmosphere. An experiment was conducted to study fluctuations of the ozone layer, the Ionosonde Total Electron Content (ITEC) and the peak electron density height (hmF2) in the ionosphere, as well as at a number of other parameters before, during and after the total solar eclipse. We found the existence of dominant oscillations with periods ranging between 30–40 min in most of the parameters. Cross-spectrum analyses between total ozone and various atmospheric parameters resulted to statistically significant square coherences between the observed oscillations, while the respective phase spectra show that the perturbation originates in the stratosphere and reaches the various layers at speeds around 20 km min−1. Additional evidence supporting these findings was provided by the amplitude of the oscillations in the ionospheric electron density, which increased upwards from 160 to 220 km height.
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Uchida, Kazunori, Masafumi Takematsu, Jun-Hyuck Lee und Junichi Honda. „Parameter Estimation for Propagation along Random Rough Surface by Using Line of Sight Data“. Mobile Information Systems 10, Nr. 3 (2014): 307–19. http://dx.doi.org/10.1155/2014/172910.
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This paper is concerned with a numerical procedure to estimate two parameters, amplitude modification factor α and propagation order of distance β, for electromagnetic (EM) propagation in complicated natural environments such as random rough surface (RRS). These two parameters are key parameters when we simulate field distributions along various types of RRS based on 1-ray model. We assume that the former parameter α can be evaluated by the visual planar angles of illuminated lines in case of 1D RRS and by the visual solid angles of illuminated planes in case of 2D RRS. We also assume that the latter parameter β can be estimated not only by base station (BS) antenna height, similar to Okumura-Hata model simulating EM propagation in urban and suburban areas, but also by mobile station (MS) antenna height. In order to demonstrate validity of the proposed parameter estimation, we compare the numerical field distributions obtained by the 1-ray model using estimated two parameters with those computed by discrete ray tracing method (DRTM) which is an effective EM field solver. It is shown that both numerical results are in good agreement.
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Chiu, M. C., Y. C. Chang, L. J. Yeh und C. H. Chung. „Optimal Design of a Vibration-Based Electromagnetic Energy Harvester Using a Simulated Annealing Algorithm“. Journal of Mechanics 28, Nr. 4 (16.10.2012): 691–700. http://dx.doi.org/10.1017/jmech.2012.104.
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ABSTRACTThis paper presents the optimal design of an electromagnetic vibration-based generator using the simulated annealing method (SA). To optimally extract the vibrational energy of a system vibrating at a specific frequency, the selected mass and spring stiffness of a resonant vibration is required. The relationship between induced energy and the generator's structure, its permanent magnet height and diameter, number of turns, and wire diameter in a single air coil are discussed. Also, a prototype of the vibrationbased electrical generator is built and tested via a shaker excited at resonance frequency and input amplitude of 0.06mm. Consequently, results reveal that the design parameters (permanent magnet height and diameter, number of turns, and wire diameter) play essential roles in maximizing electrical power.
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Swirad, S. „High-precision finishing hard steel surfaces using hydrostatic burnishing tool“. MATEC Web of Conferences 249 (2018): 03002. http://dx.doi.org/10.1051/matecconf/201824903002.
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The objective of this research aims to improve surface roughness of the hardened 145Cr6 (DIN) steel using the hydrostatic burnishing tool. The ball burnishing process with hydrostatic tools is very economical finishing process for various types of machine parts. This process reduces the height of surface unevenness, introduces compressive stresses at high depth (approx. 1 mm) and increase the hardness of the surface layer. The flat surface optimal ball burnishing parameters have been determined after conducting the Taguchi L9 matrix experiment. The input parameters are speed, burnishing force and burnishing width. It also showed a positive effect of hydrostatics burnishing on roughness and geometric structure of the surface. In most cases, the result is anisotropic surface, reduced roughness, reduced amplitude values of parameters such as: Sa, Sz.
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Zhou, L. F., P. F. Ma, Y. Xia und C. H. Xie. „MONITORING THE DEFORMATION OF HIGH-RISE BUILDINGS IN SHANGHAI LUIJIAZUI ZONE BY TOMO-PSINSAR“. ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-3 (02.05.2018): 2535–39. http://dx.doi.org/10.5194/isprs-archives-xlii-3-2535-2018.
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In this study, we utilize a Tomography-based Persistent Scatterers Interferometry (Tomo-PSInSAR) approach for monitoring the deformation performances of high-rise buildings, i.e. SWFC and Jin Mao Tower, in Shanghai Lujiazui Zone. For the purpose of this study, we use 31 Stripmap acquisitions from TerraSAR-X missions, spanning from December 2009 to February 2013. Considering thermal expansion, creep and shrinkage are two long-term movements that occur in high-rise buildings with concrete structures, we use an extended 4-D SAR phase model, and three parameters (height, deformation velocity, and thermal amplitude) are estimated simultaneously. Moreover, we apply a two-tier network strategy to detect single and double PSs with no need for preliminary removal of the atmospheric phase screen (APS) in the study area, avoiding possible error caused by the uncertainty in spatiotemporal filtering. Thermal expansion is illustrated in the thermal amplitude map, and deformation due to creep and shrinkage is revealed in the linear deformation velocity map. The thermal amplitude map demonstrates that the derived thermal amplitude of the two high-rise buildings both dilate and contract periodically, which is highly related to the building height due to the upward accumulative effect of thermal expansion. The linear deformation velocity map reveals that SWFC is subject to deformation during the new built period due to creep and shrinkage, which is height-dependent movements in the linear velocity map. It is worth mention that creep and shrinkage induces movements that increase with the increasing height in the downward direction. In addition, the deformation rates caused by creep and shrinkage are largest at the beginning and gradually decrease, and at last achieve a steady state as time goes infinity. On the contrary, the linear deformation velocity map shows that Jin Mao Tower is almost stable, and the reason is that it is an old built building, which is not influenced by creep and shrinkage as the load is relaxed and dehydration proceeds. This study underlines the potential of the Tomo-PSInSAR solution for the monitoring deformation performance of high-rise buildings, which offers a quantitative indicator to local authorities and planners for assessing potential damages.
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Gasanbekova, F. A., O. Y. Antonova, K. U. Kurkiev und M. K. Gadzhimagomedova. „HEIGHT OF TRITICALE SAMPLE PLANTS OF DIFFERENT ORIGIN AND PLOIDY LEVEL“. Scientific Life 15, Nr. 7 (31.07.2020): 941–49. http://dx.doi.org/10.35679/1991-9476-2020-15-7-941-949.
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The great attention that is now being paid to triticale by breeders is due to the hopes of combining in one organism all the valuable that wheat and rye can give. The study of morphological characters using the most typical samples of triticale, characterizing the ecologicalgeographic and genotypic diversity of this synthetic genus, allows us to reveal the patterns of their variability for use in breeding programs and in taxonomy. As a result of studying 36 samples of triticale of various origins and ploidy different levels in terms of plant height and resistance to lodging, it was found that there is a very close correlation between these two parameters. Spring and winter forms significantly differ from each other in terms of plant height. Spring forms are lower than winter ones. The largest number of spring triticale samples have plant height from 110 to 130 cm, and hexaploids – from 130 to 150 cm. The majority of hexaploid triticale spring forms were obtained in Mexico and Russia. Mexican triticale plants are much lower in height than Russian ones. A close correlation was established between the resistance to lodging of triticale plants and the length of the stem. As a rule, specimens with heights not higher than 115 cm are characterized by high resistance to lodging. The amplitude of variability in plant height in triticale is quite significant at all ploidy levels. The range of variation in plant height is greatest at the hexaploid level – from 50 to 200 cm. In tetraploids it ranges from 70 to 160 cm, in octoploids – from 80 to 170 cm. The highest average value of plant height in octoploid forms of triticale is 133.8 cm, in tetraploids – 122.7 cm, and the smallest in hexaploids – 114.5 cm. This is explained by intensive selection work carried out at this level of ploidy.
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Borodulin, Dmitry, Dmitry Sukhorukov, Olga Musina, Margarita Shulbaeva, Tatyana Zorina, Dmitry Kiselev und Ekaterina Miller. „Flour Baking Mixes: Optimal Operating Parameters for Vibration Mixers“. Food Processing: Techniques and Technology 51, Nr. 1 (25.03.2021): 196–208. http://dx.doi.org/10.21603/2074-9414-2021-1-196-208.
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Introduction. New long-storage flour baking mixes are a promising direction in the development of healthy diets. The research objective was to identify the rational parameters for using continuous vibration mixers in flour production.
Study objects and methods. The study featured wheat flour baking mixes. A correlation analysis helped to build mathematical models of the mixing process in vibration mixers using the sequential dilution method. By comparing the smoothing ability of several mixers, the authors identified their feasibility. The research included two full-factor laboratory experiments.
Results and discussion. The paper gives a brief review of modern mixing equipment and describes the effect of uneven feeding of bulk materials on the quality of the finished mixes. The vertical vibration mixers proved to be an optimal technical solution. The experiment featured the effect of the amplitude A (m), vibration frequency f (Hz), vibration angle β (°), and the height of the vibrofluidized bed on the process.
Conclusion. The research revealed the following optimal technological parameters: A = 0.0046 m, f = 33.48 Hz, the share of food salt = 0.05. Continuous vibration mixers provided uniform high-quality baking mixes.