Evaluation of a New Photodiode Sensor for Measuring Global and Diffuse Irradiance, and Sunshine Duration

2003 ◽  
Vol 125 (1) ◽  
pp. 43-48 ◽  
Author(s):  
John Wood ◽  
Tariq Muneer ◽  
J. Kubie
Keyword(s):  
Standard Error ◽  
Sunshine Duration ◽  
New Device ◽  
Global Irradiance ◽  
Diffuse Irradiance ◽  
Reference Measure ◽  
Irradiance Data ◽  
Stable Performance ◽  
Integrated Device ◽  
Story Building

A new integrated device (called the BF3) has been developed, which enables the simultaneous measurement of horizontal global and diffuse irradiance as well as sunshine presence at any time. The sensor needs no specific polar alignment or routine adjustment, and works at any latitude. To evaluate the performance of this new device, a BF3 sensor was installed on the roof of a six-story building in the Merchiston Campus of Napier University, Edinburgh from February 22–July 3, 2001. Horizontal global and diffuse irradiance data were collected from the BF3. To enable a cross check, two Kipp and Zonen CM11 sensors, one with a shade ring, have also been installed beside the BF3 sensor on the same roof. These were used to give a reference measure of the horizontal global and diffuse irradiance. To evaluate the BF3 sunshine duration performance, the direct beam normal irradiance was calculated from the CM11 global and diffuse readings, and compared with a threshold of 120W.m−2 to give sunshine presence according to the WMO definition. This was compared against the BF3 output, and also with data from two Campbell-Stokes sunshine recorders on the same site. The results show a stable performance on the part of the BF3 sensor for the measurement of horizontal global and diffuse irradiance. The global irradiance measured by the BF3 showed values 4.7% high, with a standard error of 16.5W.m−2 compared to the Kipp and Zonen sensors. Diffuse values were 1.4% high with a standard error of 13.4W.m−2. The BF3 sunshine duration was within 2% of that calculated from the WMO definition over the study period, with a typical daily error of less than 20 min. This is well within the WMO requirements for a sunshine recorder. In comparison, the Campbell-Stokes recorders gave readings up to 7% different from the WMO values, with a typical daily error of almost an hour.

scholarly journals Comparison of Pyranometric and Pyrheliometric Methods for the Determination of Sunshine Duration

2007 ◽  
Vol 24 (5) ◽  
pp. 835-846 ◽  
Author(s):  
Yvonne B. L. Hinssen ◽  
Wouter H. Knap
Keyword(s):  
Solar Irradiance ◽  
Extreme Values ◽  
Sunshine Duration ◽  
Global Radiation ◽  
Surface Radiation ◽  
Global Irradiance ◽  
Correlation Algorithm ◽  
Mean Differences ◽  
Radiation Measurements

Abstract Two pyranometric methods for the determination of sunshine duration (SD) from global irradiance measurements are evaluated by means of summated sunshine seconds derived from pyrheliometric measurements in combination with the WMO threshold of 120 W m−2 for the direct solar irradiance. The evaluation is performed using direct and global radiation measurements made at the Cabauw Baseline Surface Radiation Network (BSRN) site in the Netherlands for the period March 2005–February 2006. The “Slob algorithm” uses 10-min mean and extreme values of the measured global irradiance and parameterized estimates of the direct and diffuse irradiance. The “correlation algorithm” directly relates SD to 10-min mean measurements of global irradiance. The cumulative pyrheliometric SD for the mentioned period is 1429 h. Relative to this value, the Slob algorithm and correlation algorithm give −72 h (−5%) and +8 h (+0.6%). On a daily mean basis, the values are −0.22 ± 0.05 h day−1 and 0.03 ± 0.03 h day−1, respectively. By means of tuning the irradiance parameterizations of the Slob algorithm, the yearly cumulative and daily mean differences can be reduced to +7 h (+0.5%) and 0.02 ± 0.04 h day−1, respectively. It is concluded that, by use of either algorithm, it is possible to estimate daily sums of SD from 10-min mean measurements of global irradiance with a typical uncertainty of 0.5–0.7 h day−1. For yearly sums, the uncertainty typically amounts to 0.5%.

scholarly journals Test–Retest Reliability of a New Device Versus a Long-Arm Goniometer to Evaluate Knee Proprioception

2021 ◽  
pp. 1-6
Author(s):  
Fei Tian ◽  
Yaqi Zhao ◽  
Jixin Li ◽  
Wenjin Wang ◽  
Danni Wu ◽  
...  
Keyword(s):  
Standard Error ◽  
Intraclass Correlation ◽  
Correlation Coefficients ◽  
Joint Position Sense ◽  
Repeated Measurements ◽  
Good Reliability ◽  
Retest Reliability ◽  
New Device ◽  
Intraclass Correlation Coefficients ◽  
Test Retest Reliability

Context: Many methods used to evaluate knee proprioception have shortcomings that limit their use in clinical settings. Based on an inexpensive 3D camera, a new portable device was recently used to evaluate the joint position sense (JPS) of the knee joint. However, the test–retest reliability of the new method remains unclear. This study aimed to evaluate the test–retest reliability of the new device and a long-arm goniometer for assessing knee JPS, and to compare the variability of the 2 methods. Design: Prospective observational study of the test–retest reliability of knee JPS measurements. Methods: Twenty-one healthy adults were tested in 2 sessions with a 1-week interval. Three target knee flexion angles (30°, 45°, and 60°) were reproduced in each session. Target and reproduced angles were measured with both methods. Intraclass correlation coefficients, standard error of the measurement, and Bland–Altman plots were used to quantify test–retest reliability. Paired t tests were used to compare knee JPS (absolute error of the target-reproduced angle) between the methods. Results: The new device (good to excellent intraclass correlation coefficients .74–.80; standard error of the measurement 0.52°–0.61°) demonstrated better test–retest reliability than the goniometer (poor to fair intraclass correlation coefficients .23–.43; standard error of the measurement 0.89°–2.07°) and better test–retest agreement (respective mean differences for the 30°, 45°, and 60° knee angles: 0.11°, 0.13°, and 0.41° for the new system; 0.84°, 1.52°, and 1.18° for the goniometer). The measurements (absolute errors of the target-reproduced angles) with the goniometer were significantly greater than those with the new device (P < .05); the SDs of repeated measurements with the goniometer (1.50°–2.41°) were greater than with the new device (1.08°–1.38°). Conclusions: Given that the new device has good reliability and sufficient precision, it is the better alternative for evaluating knee JPS. Goniometers should be used with caution to assess knee JPS.

scholarly journals Proxy-based reconstruction of erythemal UV doses over Estonia for 1955–2004

2006 ◽  
Vol 24 (7) ◽  
pp. 1767-1782 ◽  
Author(s):  
K. Eerme ◽  
U. Veismann ◽  
S. Lätt
Keyword(s):  
Sunshine Duration ◽  
Volcanic Eruptions ◽  
Average Value ◽  
Global Irradiance ◽  
Atmospheric Turbidity ◽  
Fine Weather ◽  
Summer Half ◽  
Yearly Dose ◽  
Relative Sunshine ◽  
Relative Sunshine Duration

Abstract. A proxy-based reconstruction of the erythemally-weighted UV doses for 1955-2004 has been performed for the Tartu-Tõravere Meteorological Station (58°16' N, 26°28' E, 70 m a.s.l.) site. The pyrheliometer-measured daily sum of direct irradiance on partly cloudy and clear days, and the pyranometer-measured daily sum of global irradiance on overcast days were used as the cloudiness influence related proxies. The TOMS ozone data have been used for detecting the daily deviations from the climatic value (averaged annual cycle). In 1998–2004, the biases between the measured and reconstructed daily doses in 55.5% of the cases were within ±10% and in 83.5% of the cases within ±20%, on average. In the summer half-year these amounts were 62% and 88%, respectively. In most years the results for longer intervals did not differ significantly, if no correction was made for the daily deviations of total ozone from its climatic value. The annual and summer half-yearly erythemal doses (contributing, on average, 89% of the annual value) agreed within ±2%, except for the years after major volcanic eruptions and one extremely fine weather year (2002). Using the daily relative sunshine duration as a proxy without detailed correction for atmospheric turbidity results in biases of 2–4% in the summer half-yearly dose in the years after major volcanic eruptions and a few other years of high atmospheric turbidity. The year-to-year variations of the summer half-yearly erythemal dose in 1955–2004 were found to be within 92–111% relative to their average value. Exclusion of eight extreme years reduces this range for the remaining to 95–105.5%. Due to the quasi-periodic alternation of wet and dry periods, the interval of cloudy summers 1976–1993 regularly manifests summer half-yearly erythemal dose values lower than the 1955–2004 average. Since 1996/1997 midwinters have been darker than on average.

Estimation of sunshine duration from the global irradiance measured by a photovoltaic silicon solar cell

2014 ◽  
Vol 36 ◽  
pp. 26-33 ◽  
Author(s):  
M. Vivar ◽  
M. Fuentes ◽  
M. Norton ◽  
G. Makrides ◽  
I. de Bustamante
Keyword(s):  
Solar Cell ◽  
Silicon Solar Cell ◽  
Sunshine Duration ◽  
Global Irradiance

scholarly journals Solar Radiation Changes in the United States during the Twentieth Century: Evidence from Sunshine Duration Measurements

2005 ◽  
Vol 18 (10) ◽  
pp. 1503-1512 ◽  
Author(s):  
Gerald Stanhill ◽  
Shabtai Cohen
Keyword(s):  
United States ◽  
Twentieth Century ◽  
Solar Radiation ◽  
Linear Time ◽  
Sunshine Duration ◽  
Volcanic Eruptions ◽  
The United States ◽  
Past Century ◽  
Global Irradiance ◽  
The U.S

Abstract Changes in sunshine duration (SS) measured in the conterminous United States during the past century were used as a proxy to explore changes in shortwave forcing at the earth’s surface when and where accurate measurements of global irradiance (Eg) were not available. Yearly totals of SS from the 106 Weather Bureau stations with 70 or more years of complete measurements between 1891 and 1987 were analyzed after establishing that the two changes in instrumentation during that period had not significantly influenced the measurements. Annual totals of SS were highly correlated (r2 = 0.86) with annual totals of global irradiance (Eg↓) measured at the 26 U.S. pyranometer stations during the 1977–80 period when the Solar Radiation Network (SOLRAD) was operating at its maximum accuracy. The linear relationship between annual totals of Eg↓ and SS was highly significant (P &lt; 0.001), with each additional hour of sunshine duration equivalent to an increase of 0.0469 ± 0.002 W m−2 (or 1.48 ± 0.07 MJ m−2 solar radiation per year). The error term of annual values of Eg↓ estimated from SS was 5%. Almost half of the sunshine series showed significant linear time trends in SS. At 27 sites it increased significantly with time; at 21 sites it significantly decreased. Regionally, in the northwest quarter of the U.S. landmass (&gt;36°N, &gt;98°W), SS increased at nine sites and decreased at three; in the three other quarters of the United States, the numbers of sites with increasing and decreasing trends were equal. After 1950, a larger proportion of series showed decreases in sunshine duration, and more sites showing decreasing SS were found in the Northeast and in the West and South of the United States, but these regional differences were not significant. Normalized annual anomalies of SS averaged for all of the U.S. series showed no significant linear time trend during the last century, but the running 11-yr average values indicated clear peaks in the fourth and sixth decades of the last century and troughs in the first, fifth, and seventh decades; the peaks coincided with those reported for continental air temperature, and the troughs coincided with those for continental rainfall. A significant periodic component (with a median period of 10 yr) was found in half of the SS series; however the peak spectral density averaged for the United States, occurring at a period of 11.25 yr, was not significantly above that expected for the white noise level. An analysis of long-term records from outside the United States showed that the sensitivity of SS to Eg↓ was dependent on both astronomical and climatic factors, and the implications of this site dependence on the accuracy of this proxy relationship is discussed. A decline in SS followed major volcanic eruptions in North America. In the case of El Chichon, this change was calculated to have resulted in a negative shortwave radiative forcing of 6.4 W m−2 for the United States, some 3 times greater than the value calculated from the direct effect of the increase in aerosol loading. It is concluded that the U.S. sunshine duration database shows little evidence for a significant trend in solar forcing at the earth’s surface during the twentieth century. To reconcile this discrepancy with reports of decreases in Eg↓ measured in the United States during the last half century requires a more detailed understanding of the influence of clouds and aerosols on sunshine duration.

scholarly journals THE SKY RADIANCE AND LUMINANCE DISTRIBUTIONS ESTIMA TED BY GLOBAL IRRADIANCE AND DIFFUSE IRRADIANCE

2003 ◽  
Vol 68 (573) ◽  
pp. 33-40 ◽  
Author(s):  
Norio IGAWA ◽  
Hirohi NAKAMURA ◽  
Yasuko KOGA ◽  
Tomoko MATSUZAWA
Keyword(s):  
Global Irradiance ◽  
Diffuse Irradiance ◽  
Sky Radiance

Structural Optimization Design and Experiment Investigation of Electric-Pneumatic Converter Device Based on the Principle of Nozzle Flapper

2012 ◽  
Vol 490-495 ◽  
pp. 543-547
Author(s):  
Dong Ming Li ◽  
Xiao Jing Tian ◽  
Ying Jia ◽  
Yun Xian Cui
Keyword(s):  
Optimization Design ◽  
Low Voltage ◽  
Orthogonal Experiment ◽  
Fast Response ◽  
Parameters Optimization ◽  
Force Balance ◽  
Piezoelectric Composite ◽  
New Device ◽  
Piezoelectric Structure ◽  
Stable Performance

In this paper, a new electric-pneumatic convert device with piezoelectric composite disc as actuator is proposed. The new convert device break through traditional principle of force balance, which the parameters optimization to the whole air course and the structure of piezoelectric actuators were carried on by orthogonal experiment method. Experimental results show that the new device character is effected seriously by original installation site and has the characters of fast response, sensitive reaction, stable performance and meet the requirement of air pressure output between 0.02MPa and 0.1 MPa in industrial field with low voltage, which provides good basis of development of electric-pneumatic convert valve with new piezoelectric structure.

A New Method for Correcting Shadow Band Diffuse Irradiance Data

2001 ◽  
Vol 124 (1) ◽  
pp. 34-43 ◽  
Author(s):  
T. Muneer ◽  
X. Zhang
Keyword(s):  
Beam Energy ◽  
Polar Axis ◽  
Site Specific ◽  
Beer Sheva ◽  
Diffuse Irradiance ◽  
Proposed Model ◽  
Irradiance Data ◽  
Comparison Of The Results ◽  
Sky Conditions ◽  
Diffuse Distribution

An instrument commonly used to measure diffuse irradiance is the polar-axis shadow band pyranometer. However, the shadow band that is used to prevent the beam energy from entering the pyranometer also obscures part of sky-diffuse irradiance. A correction factor must hence be applied to obtain as accurate as possible the estimation of the true diffuse irradiance. In this article, the development of a new model based on an anisotropic sky-diffuse distribution theory is presented. The proposed model is validated using two databases from different sites with various sky conditions. Drummond’s method, which is based on geometrical calculation, is also examined using the same databases. Comparison of the results obtained through application of the proposed model, with those generated by Drummond’s method shows that, for the case of Bracknell, UK the proposed method gives a root mean square error (RMSE) of 12 W/m2, as compared to Drummond’s figure of 16 W/m2. For the case of Beer Sheva, Israel the proposed model produces an RMSE of 17 W/m2, while Drummond’s procedure results in 23 W/m2. It has been demonstrated herein that the proposed method is not site specific.

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