10-minute Mean Research Articles

Abstract 55: Cerebral Autoregulatory Curves in Postpartum Individuals With and Without Preeclampsia

Introduction: Risk of maternal stroke is higher in patients with preeclampsia (PEC), with the highest risk seen in those with chronic hypertension with superimposed preeclampsia (siPEC). Most strokes occur postpartum. Changes in cerebral autoregulation (CA) could contribute to elevated postpartum stroke risk. We describe CA curves in postpartum patients with no hypertension, PEC and siPEC. Methods: We prospectively recruited postpartum patients with and without PEC and measured 10-minute continuous mean arterial pressure (MAP) and cerebral blood flow velocity (CBFV) with finger plethysmography and transcranial Doppler within 1 week of delivery. We generated polynomial S-curves to derive limits of CA, CA plateaus (defined as slope < 0.15), and mean and minimum slopes between CA limits. We calculated Pearson correlation coefficients (Mx) between normalized MAP and CBVF; Mx > 0.3 indicates high MAP-CBFV correlation, suggesting impaired CA. Results: CA curves were produced from 71 patients (28% normotensive, 42% PEC, 30% siPEC). Group means for MAP were higher in those with PEC and siPEC (normotensive 72 mmHg, PEC 88, siPEC 87 [p=0.001]). CA was preserved in all groups, with Mx nadirs below 0.3 (Figure). The normotensive group demonstrated a wide, flat plateau in the S-curve (minimum slope 0.02). In the PEC group, we observed a narrower and slightly steeper autoregulatory plateau (minimum slope 0.05). The siPEC group displayed the narrowest and steepest plateau (minimum slope 0.15). Conclusion: In conclusion, in our sample of postpartum patients with normotension, PEC and siPEC, we observed a gradient in CA plateau range and slope. Compared with the normotensive group, the PEC and siPEC groups had progressively narrower and steeper CA plateaus, suggesting a more limited CA range and diminished CA efficacy. Future studies should investigate whether sustained MAP outside CA limits contributes to adverse maternal outcomes, particularly in those with siPEC.

Probabilistic modeling of wind characteristics for long-span cable-stayed bridges based on field measurements considering deck disturbance effects

To assess the reliability of wind resistance behavior for long-span cable-stayed bridges, this study establishes a joint probability distribution model for 10-minute mean wind speed and turbulence intensity based on one year of field monitoring data. Firstly, the distribution characteristics of wind parameters at the deck height are investigated. Notably, substantial abnormalities are observed in the anemometer data obtained from the upstream and downstream sides of the mid-span deck. Thus, a novel component-decomposition method is proposed to eliminate these inconsistencies. The decrease in measured mean wind speed and the increase in turbulence intensity resulting from the bridge deck disturbance is considered to restore the actual wind parameters. Finally, the joint probability distribution model is developed using the Gaussian Copula function. The results demonstrate the efficacy of the proposed method in mitigating the bridge deck disturbance on field measurements, thereby establishing accurate and reliable probability distribution models.

SCADA data for wind turbine data-driven condition/performance monitoring: A review on state-of-art, challenges and future trends

This paper reviews the recent advancement made in data-driven technologies based on SCADA data for improving wind turbines’ operation and maintenance activities (e.g. condition monitoring, decision support, critical components failure detections) and the challenges associated with them. Machine learning techniques applied to wind turbines’ operation and maintenance (O&M) are reviewed. The data sources, feature engineering and model selection (classification, regression) and validation are all used to categorise these data-driven models. Our findings suggest that (a) most models use 10-minute mean SCADA data, though the use of high-resolution data has shown greater advantages as compared to 10-minute mean value but comes with high computational challenges. (b) Most of SCADA data are confidential and not available in the public domain which slows down technological advancements. (c) These datasets are used for both, the classification and regression of wind turbines but are used in classification extensively. And, (d) most commonly used data-driven models are neural networks, support vector machines, probabilistic models and decision trees and each of these models has its own merits and demerits. We conclude the paper by discussing the potential areas where SCADA data-based data-driven methodologies could be used in future wind energy research.

Coastal Wind Measurements Using a Single Scanning LiDAR

A wind measurement campaign using a single scanning light detection and ranging (LiDAR) device was conducted at the Hazaki Oceanographical Research Station (HORS) on the Hazaki coast of Japan to evaluate the performance of the device for coastal wind measurements. The scanning LiDAR was deployed on the landward end of the HORS pier. We compared the wind speed and direction data recorded by the scanning LiDAR to the observations obtained from a vertical profiling LiDAR installed at the opposite end of the pier, 400 m from the scanning LiDAR. The best practice for offshore wind measurements using a single scanning LiDAR was evaluated by comparing results from a total of nine experiments using several different scanning settings. A two-parameter velocity volume processing (VVP) method was employed to retrieve the horizontal wind speed and direction from the radial wind speed. Our experiment showed that, at the current offshore site with a negligibly small vertical wind speed component, the accuracy of the scanning LiDAR wind speeds and directions was sensitive to the azimuth angle setting, but not to the elevation angle setting. In addition to the validations for the 10-minute mean wind speeds and directions, the application of LiDARs for the measurement of the turbulence intensity (TI) was also discussed by comparing the results with observations obtained from a sonic anemometer, mounted at the seaward end of the HORS pier, 400 m from the scanning LiDAR. The standard deviation obtained from the scanning LiDAR measurement showed a greater fluctuation than that obtained from the sonic anemometer measurement. However, the difference between the scanning LiDAR and sonic measurements appeared to be within an acceptable range for the wind turbine design. We discuss the variations in data availability and accuracy based on an analysis of the carrier-to-noise ratio (CNR) distribution and the goodness of fit for curve fitting via the VVP method.

General Sea State and Drag Coefficient Observed near Shore in Taiwan Strait

The general characteristics of wind waves and drag coefficient are studied using the data from the buoy observation near shore in Taiwan Strait. An algorithm of the bulk aerodynamic method using 10-minute mean wind speed and the temperature difference between the air and sea surface was developed to calculate the equivalent wind speed at 10 m in height and the surface friction velocity. The observation shows that the sea states contains a wide range of wave ages driven by the synoptic wind systems, i.e. the strong northeast monsoon in winter and southwest monsoon in summer, mixed with the thermally diurnal variation across the sea-land boundaries. The large-scale winds generate a number of swells with long fetch and the mesoscale circulation perpendicular to the main streams causing wind and wave misalignments. The drag coefficients display considerable scattering around the linear growth formulation along with the increase of neutral wind speed. This is attributed to the dependence of surface roughness on wave ages. The present observation confirms that the drag coefficients are sensitive to the sea state described using the Charnock constant and hence the wave ages.

An Analysis of Snow and Wind Loads Combinations Based on Meteorological Data

AbstractThe objective of this paper is to present a probabilistic method of analyzing the combinations of snow and wind loads using meteorological data and to determine their combination factors. Calculations are based on data measured at twelve Polish meteorological stations operated by the Institute for Meteorology and Water Management. Data provided are from the years 1966 - 2010. Five combinations of snow load and 10-minute mean wind velocity pressure have been considered. Gumbel probability distribution has been used to fit the empirical distributions of the data. As a result, the interdependence between wind velocity pressure and snow load on the ground for a return period of 50 years has been provided, and the values of the combination factors for snow loads and wind actions are proposed.

Impact of a feedback device on chest compression quality during extended manikin CPR: a randomized crossover study

PurposesChest compressions require physical effort leading to increased fatigue and rapid degradation in the quality of cardiopulmonary resuscitation overtime. Despite harmful effect of interrupting chest compressions, current guidelines recommend that rescuers switch every 2 minutes. The impact on the quality of chest compressions during extended cardiopulmonary resuscitation has yet to be assessed. Basic proceduresWe conducted randomized crossover study on manikin (ResusciAnne; Laerdal). After randomization, 60 professional emergency rescuers performed 2 × 10 minutes of continuous chest compressions with and without a feedback device (CPRmeter). Efficient compression rate (primary outcome) was defined as the frequency target reached along with depth and leaning at the same time (recorded continuously). Main findingsThe 10-minute mean efficient compression rate was significantly better in the feedback group: 42% vs 21% (P< .001). There was no significant difference between the first (43%) and the tenth minute (36%; P= .068) with feedback. Conversely, a significant difference was evident from the second minute without feedback (35% initially vs 27%; P< .001). The efficient compression rate difference with and without feedback was significant every minute, from the second minute onwards. CPRmeter feedback significantly improved chest compression depth from the first minute, leaning from the second minute and rate from the third minute. Principal conclusionsA real-time feedback device delivers longer effective, steadier chest compressions over time. An extrapolation of these results from simulation may allow rescuer switches to be carried out beyond the currently recommended 2 minutes when a feedback device is used.

Development of fatigue life prediction method and effect of 10-minute mean wind speed distribution on fatigue life of small wind turbine composite blade

This study aims to develop a fatigue life prediction method and to identify the effect that a 10-minute mean wind speed distribution has on the fatigue life of a small-scale wind turbine composite blade. First, combining the von Karman isotropic turbulence model and the Weibull distribution for a 10-minute mean wind speed provided us with the 1-Hz full wind history for a specific time period. Accordingly, the fatigue stress spectra at the blade's fatigue-critical locations (FCLs) were created by applying a stress tensor, in which the interaction between flapwise and edgewise bending moments was taken into consideration. The fatigue life of a composite blade can be predicted with a reliability R = 95% by applying the P–S–N curve obtained from the constant amplitude fatigue tests and rainflow cycle counting, and cumulative damage rule to the fatigue stress spectra. To acquire the second-order regression equation, nonlinear regression analysis was performed on the fatigue lives, which were simulated by using the proposed fatigue life prediction method. In this equation, the variables were the shape parameter, K, and the scale parameter, C, of the Weibull distribution for a 10-minute mean wind speed. The effects of the Weibull parameters on fatigue life were evaluated through the sensitivity analysis of the equations.

건축구조기준(KBC-2009) 기본풍속도의 개선

Since 1970s, the rapid urbanization process by industrial and economic development in Korea causes to a severe change of surface roughness and recent abnormal weather by global warming causes to increasing the intensity of strong wind and Typhoon. It is necessary to revise basic wind speed map of Korean Building Code 2009(KBC-2009) drowned by past meteorological data from 1951 to 1995. This paper proposes new basic wind speed map corresponding to a return period of 100 years in Korea. The values are established from data of annual-maximum 10-minute mean wind speeds collected at 68 meteorological offices recent past 40 years from 1973 to 2012. They were standardized homogeneously to an altitude 10m above the surface roughness category C. Surface roughness category was determined by surrounding surface conditions of meteorological station in 1999 and 2012. The data were statistically reduced using extreme value analysis procedures based on Gumbel's distribution, and the expected wind speeds corresponding to a return period of 100 years (it is called as basic wind speeds) were calculated for each region. The equivalent wind speed contour line to a return period of 100 years were drown up interval of 2m/s to the map of Korea. The basic wind speeds of this study were compared with those of KBC-2009, and the causes of wind speed up or down were described. The basic wind speed map of this study shall be used to revise that of KBC-2009.

Wind data collected by a fixed-wing aircraft in the vicinity of a tropical cyclone over the south China coastal waters

The fixed-wing aircraft of Government Flying Service of the Hong Kong Government has recently equipped with an upgraded meteorological measuring system. This system provides horizontal wind velocity components up to 90 m/s at an accuracy of 0.5 m/s for straight and level flight. Besides search and rescue (SAR) missions, this aircraft is also used for windshear and turbulence investigation flights at the Hong Kong International Airport. In a SAR operation in July 2009, the aircraft flew close to the eye of tropical cyclone Molave, when it was located at about 200 km to the east of Hong Kong over the south China coastal waters. The aircraft provided valuable information about the winds in association with Molave because aircraft reconnaissance for tropical cyclones is not carried out for South China Sea. Based on the aircraft measurements, the 1-second mean wind reached the maximum value of 88 knots at a height of 200 m above mean sea level. Assuming a power law with altitude with an exponent of 0.11 over open waters, the corresponding 1-second mean wind at a height of 10 m would be about 63 knots. The maximum 10-minute mean wind reached 69 knots with an average height of 260 m above mean sea level. The corresponding mean at 10 m would be about 48 knots. As such, based on the aircraft measurements (in which the aircraft might not fly into the areas of maximum winds associated with the tropical cyclone), Molave had at least a strength of tropical storm to severe tropical storm at the times of the measurements. Nowadays, the determination of the intensity of tropical cyclones over the South China Sea is normally based on remote sensing data only (e.g. radar and satellite observations). To the knowledge of the authors, the results presented in the paper are the first time that direct measurements of the winds near the centre of a tropical cyclone over the northern part of the South China Sea are made with an aircraft. Apart from the mean wind and gust, other properties of the wind field of Molave are studied, e.g. frequency spectrum of the horizontal wind data, and thus the turbulence associated with this tropical cyclone.

Field measurement and analysis of turbulence coherence for Typhoon Nuri at Macao Friendship Bridge

For the purpose of investigating the turbulent and spatial coherent characteristics of strong wind during typhoon landing period, two 3-dimensional ultrasonic anemometer stations were set up 30 m horizontally apart on the Macao Friendship Bridge to caputure the turbulent wind velocities of Typhoon Nuri. Based on the reliable and representative field measured data, the mean wind speed and direction, turbulence intensity, turbulence integral scale, turbulence power spectra, spatial correlation coefficient and coherence function were statistically evaluated. The field measurement analysis have presented the following results: 1) Two anemometer stations provided consistent results. The mean wind speed variation in time domain presented typical M-shape curves. The strong wind (10-minute mean wind speed higher than 8th grade in Beaufort wind scale) direction changed in a big range up to 122-degrees-angle, indicating the field measurements scoped over the typhoon landing period. 2) The ratio of the longitudinal, lateral and vertical turbulence intensities of the strong wind in the typhoon eye wall region was 1:0.96:0.36. Compared with the code defined ratio 1:0.88:0.5, the lateral component was larger and the vertical component was smaller. 3) The value of integral scale increased when the eye wall of Typhoon Nuri passed over the field measurement site. Before the center of Typhoon Nuri arrived, the integral scale of the strong typhoon wind was about twice compared with that for the non-typhoon wind. 4) The spatial correlation of the turbulent wind, coherence function curve and the decay factor had significant differences at different times during the typhoon process. In the eye wall of the typhoon, the horizontal spatial correlation was relatively strong and horizontally spatial correlation spectrum decayed slower with frequency increase. The minimum regressed coefficient C in coherence function model was 4.67, which is lower than the code defined low limit. The maximum decay factor was 27.75 which is larger than the code defined upper bound. The strong wind characteristic parameters of Typhoon Nuri mentioned above partly represented the turbulent and spatial coherent characteristic during strong typhoon wind period.

Measurement study on wind characteristics of Typhoon Kalmaegi on the sutong bridge

The Sutong Bridge, a cable-stayed located in the southeast coastal area of China, is vulnerable to the Pacific typhoons. From the data measured by two 3D ultrasonic anemometers at the height of 76 m and 306 m, the wind characteristics (including 10-minute mean wind speed and direction, turbulence intensity and gust factor, power spectral density and integral scale of turbulence) of Typhoon Kalmaegi are analyzed The comparison of 10-minute mean wind velocity from the two anemometers validates the reliability of wind data. The turbulence intensities (Iu, Iv, and Iw) show the decreasing trend as the mean wind speed increases. The mean value of Iv/Iu is 0.94, while that of Iw/Iu is 0.90. Discrepancy exists between field-measured power spectra and code-suggested spectra. Those results can enlarge the wind database of the southeast coastal area of China, and provide references for wind resistance evaluation of the bridge.

Meteorological observations on Mount Everest in 2005

Abstract Mount Everest, the highest point on the Earth is often referred to as the earth's third pole as such the place is relatively inaccessible and little is known about its meteorology. In April 2005, an automatic weather station was installed as the mountain's North Col (6523 m a. s. l.). According to the observational 10-minute mean and daily records, the meteorological characteristics were analyzed. All the meteorological elements displayed obvious diurnal variations during May 1 to July 22, 2005. The monthly variation of daily meteorological elements on Mount Everest coincided with that on Dingri, the closest routine meteorological station, with the high correlation co-efficients of 0.928, 0.877, 0.682, 0.755, 0.826 and 0.676 (n = 83, p < 0.001) for mean temperature, minimum temperature, maximum temperature, relative humidity, pressure and wind speed, respectively. Furthermore, the vertical mean gradient of temperature was above 0.6°C/100 m, especially for the daily maximum temperature. Most weath...

131 短波海洋レーダによる海面流速分布の測定

In order to elucidate the maintenance mechamism of abrupt large change of temperature and salinity across the Kuroshio front, measurements off sea surface current field and its temporal change were made in the sea south of the Yakushima Island from October 9 to December 7, 1992, using the HF ocean Radar system, developed at the Okinawa Radio Wave Observatory, CRL. From 10-minute mean line-of-sight component of currents measured by two independently scanning HF Radars located 10 km apart to each other at the coast of Yakushima Island, we have estimated horizontal current. vectors. hourly at grided points of 2 km interval in 50 × 20 km area. The horizontal divergence was found to have positive and negative maximum values alternately along the front rather than a narrow convergence zone along the front.

建築物設計用の基本風速分布図

This paper shows the map of Japan representing basic wind speeds which were derived by using annual maximum wind speeds observed at weather stations in Japan. The basic wind speeds shown in the map are 100-year recurrence values for the 10-minute mean wind speeds at an altitude of 10 m above a flat and open country. Annual changes of terrain roughness caused by the urbanization of regions peripheral to the weather stations were taken into special consideration. The annual maximum wind speed data were homogenized in consideration of the annual changes of terrain roughness. The results of this analysis are employed in the "Recommendations for Loads on Buildings", compiled by the Architectural Institute of Japan.