Influence of optical power calculation on LED thermal resistance test

2017 ◽  
Author(s):  
Yang Xin ◽  
Guo Wei-ling ◽  
Li Song-yu ◽  
Wang Jia-lu ◽  
Sun Jie
Keyword(s):  
Thermal Resistance ◽  
Optical Power ◽  
Resistance Test ◽  
Power Calculation

scholarly journals Influence of a Thermal Pad on Selected Parameters of Power LEDs

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3732
Author(s):  
Krzysztof Górecki ◽  
Przemysław Ptak ◽  
Tomasz Torzewicz ◽  
Marcin Janicki
Keyword(s):  
Optical Properties ◽  
Thermal Resistance ◽  
Optical Power ◽  
Junction Temperature ◽  
Operating Parameters ◽  
Cold Plate ◽  
Optical Efficiency ◽  
Forward Current ◽  
Measurement Results ◽  
Set Up

This paper is devoted to the analysis of the influence of thermal pads on electric, optical, and thermal parameters of power LEDs. Measurements of parameters, such as thermal resistance, optical efficiency, and optical power, were performed for selected types of power LEDs operating with a thermal pad and without it at different values of the diode forward current and temperature of the cold plate. First, the measurement set-up used in the paper is described in detail. Then, the measurement results obtained for both considered manners of power LED assembly are compared. Some characteristics that illustrate the influence of forward current and temperature of the cold plate on electric, thermal, and optical properties of the tested devices are presented and discussed. It is shown that the use of the thermal pad makes it possible to achieve more advantageous values of operating parameters of the considered semiconductor devices at lower values of their junction temperature, which guarantees an increase in their lifetime.

scholarly journals Thermal-wet model of knitted double jersey based on backpropagation algorithm of neural network

2020 ◽  
Vol 15 ◽  
pp. 155892501990083
Author(s):  
Xintong Li ◽  
Honglian Cong ◽  
Zhe Gao ◽  
Zhijia Dong
Keyword(s):  
Neural Network ◽  
Water Vapor ◽  
Thermal Resistance ◽  
Resistance Test ◽  
Training Algorithm ◽  
Backpropagation Algorithm ◽  
Optimal Network ◽  
Resistance Model ◽  
Hidden Layer ◽  
The Relationship

In this article, thermal resistance test and water vapor resistance test were experimented to obtain data of heat and humidity performance. Canonical correlation analysis was used on determining influence of basic fabric parameters on heat and humidity performance. Thermal resistance model and water vapor resistance model were established with a three-layered feedforward-type neural network. For the generalization of the network and the difficulty of determining the optimal network structure, trainbr was chosen as training algorithm to find the relationship between input factors and output data. After training and verification, the number of hidden layer neurons in the thermal resistance model was 12, and the error reached 10−3. In the water vapor resistance model, the number of hidden layer neurons was 10, and the error reached 10−3.

Reduction of Thermal Resistance and Optical Power Loss Using Thin-Film Light-Emitting Diode (LED) Structure

2015 ◽  
Vol 62 (11) ◽  
pp. 6925-6933 ◽  
Author(s):  
Huan Ting Chen ◽  
Yuk Fai Cheung ◽  
Hoi Wai Choi ◽  
Siew Chong Tan ◽  
S. Y. Hui
Keyword(s):  
Thin Film ◽  
Thermal Resistance ◽  
Power Loss ◽  
Light Emitting Diode ◽  
Optical Power ◽  
Light Emitting

Intraocular lenses optic power calculation with seven formulas in short eyes

2021 ◽  
pp. 57-61
Author(s):  
K.B. Pershin ◽  
◽  
N.F. Pashinova ◽  
I.A. Likh ◽  
А.Y. Tsygankov ◽  
...  
Keyword(s):  
Axial Length ◽  
Mean Absolute Error ◽  
Optical Power ◽  
Absolute Error ◽  
Intraocular Lenses ◽  
Power Calculation ◽  
Retrospective Comparison ◽  
Monofocal Iol ◽  
The Mean ◽  
Axial Eye Length

Purpose. The choice of the optimal formula for calculating the IOL optical power in patients with an axial eye length of less than 20 mm. Material and methods. A total of 78 patients (118 eyes) were included in the prospective study. 1st group included 30 patients (52 eyes) with short eyes (average axial eye length of 19.60±0.42 (18.54–20.0) mm), 2nd group consisted of 48 patients (66 eyes) with a axial length 22.75±0.46 (22.0–23.77) mm. Various monofocal IOL models were used. The average follow-up period was 13 months. IOL optical power was calculated using the SRK/T formula, retrospective comparison – according to the formulas Hoffer-Q, Holladay II, Olsen, Haigis, Barrett Universal II and Kane. Results. In 1st group, the mean absolute error was determined for the formulas Haigis, Olsen, Barrett Universal II, Kane, SRK/T, Holladay II and Hoffer-Q (0.85, 0.78, 0.21, 0.17, 0.79, 0.73, 0.19 respectively). When comparing the formulas, significant differences were found for the formulas Hoffer-Q, Barrett Universal II and Kane in comparison with the formulas Haigis, Olsen, SRK/T and Holladay II (p<0.05) in all cases, respectively. In 2nd group, the mean absolute error was determined for the formulas Haigis, Olsen, Barrett Universal II, Kane, SRK/T, Holladay II and Hoffer-Q (0.15, 0.16, 0.23, 0.10, 0.19, 0.23, 0,29 respectively). In 2nd group, there were no significant differences between the studied formulas (p>0.05). Conclusion. This paper presents an analysis of data on the effectiveness of seven formulas for calculating the IOL optical power in short (less than 20 mm) eyes in comparison with the normal axial length. The advantage of the Hoffer-Q, Barrett Universal II and Kane formulas over Haigis, Holladay II, Olsen, and SRK/T is shown. Key words: cataract, hypermetropia, short eyes, calculation of the IOL optical power.

scholarly journals Optimization of the IOL optical power calculation in patients with complicated cataract and pseudoexfoliative syndrome

2016 ◽  
pp. 18-21 ◽  
Author(s):  
Y.N. Panteleyev ◽  
◽  
M.Z. Frankovska-Gierlak ◽  
A.N. Bessarabov ◽  
V.C. Chubar ◽  
...  
Keyword(s):  
Optical Power ◽  
Power Calculation ◽  
Complicated Cataract

57 EFFECT OF CHOLESTANOL OR CHOLESTEROL ON THE MOTILITY OF FROZEN GOAT SPERMATOZOA AFTER A THERMAL RESISTANCE TEST

2014 ◽  
Vol 26 (1) ◽  
pp. 142
Author(s):  
B. G. Silva ◽  
E. A. Moraes ◽  
W. C. G. Matos ◽  
C. S. Oliveira ◽  
W. D. Ferrari Junior ◽  
...  
Keyword(s):  
Thermal Resistance ◽  
Liquid Nitrogen ◽  
Semen Analysis ◽  
Egg Yolk ◽  
Water Bath ◽  
Resistance Test ◽  
Computer Assisted ◽  
Progressive Motility ◽  
Working Solution ◽  
Analysis System

The objective of the present study was to determine the concentration of cholesterol or cholestanol-loaded-cyclodextrin that needs to be added to goat sperm before cryopreservation to optimize its survival. The cholesterol or cholestanol loaded methyl-β-cyclodextrin was prepared as described by Moraes et al. (2010 Anim. Reprod. Sci. 118, 148–154). A working solution of the cholesterol or cholestanol-loaded cyclodextrin was prepared by adding 50 mg of each one to 1 mL of TALP at 37°C and mixing the solution briefly using a vortex mixer. Ejaculates (n = 24) from 5 bucks were used for this experiment. Sperm from each ejaculate were diluted 1 : 1 (vol : vol) in Tris diluent (200 mM Tris, 65 mM citric acid, and 55 mM glucose) and centrifuged at 800 × g for 10 min. The pellets were resuspended to a concentration of 120 × 106 sperm mL–1 in Tris and subdivided into 7 aliquots of 5 mL each (600 × 106 total sperm). Sperm were treated in 7 treatment groups that received no additive (0 mg; control) or different levels of cholesterol or cholestanol (0.75, 1.5, or 3.0 mg/120 × 106 sperm). All treatments were incubated for 15 min at room temperature and then cooled to 4°C over 2 h. The samples were diluted with Tris-egg yolk diluent containing 2% glycerol. The sperm were packaged into 0.5-cc straws and frozen in static liquid nitrogen vapor for 20 min and then straws were plunged into liquid nitrogen and stored until analysed for motility and thermal resistance test using a computer-assisted semen analysis system (CASA). Two straws from each treatment were thawed in a 37°C water bath for 30 s and extended in Tris. For the thermal resistance test, after thawing, 0.5 mL of semen from each treatment was placed in 1.5-mL tubes in a water bath at 37°C for 3 h. At 0, 60, 120, and 180 min, subsamples were evaluated for sperm total and progressive motility using a computer-assisted sperm motion analyzer. A total of 200 spermatozoa were counted in at least 5 different fields. Data were analysed using ANOVA and treatment means were separated, using the SNK test at 5% probability. Cholesterol (0.75 mg; 46.7%) and cholestanol (1.5 mg; 40.5%) produced an increase in progressive motility compared with other treatments after 1 h of incubation (P < 0.05). However, cholestanol (0.75 mg; 39.5 and 31%) was higher for total and progressive motility after 3 h of sperm incubation compared with the control (27 and 17.8%; P < 0.05), respectively. The addition of 0.75 mg of cholestanol in fresh sperm before cryopreservation improved the motility of freeze-thawed goat sperm compared with cholesterol. Therefore, adding cholestanol to goat sperm membranes improved cell cryosurvival. Supported by Fundação de Amparo à Ciência e Tecnologia de Pernambuco (FACEPE) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq).

scholarly journals Influence of the anterior chamber depth on the accuracy of IOL optical power calculation in short eyes

2021 ◽  
Author(s):  
Кирилл Борисович Першин ◽  
Надежда Федоровна Пашинова ◽  
Иван Александрович Лих ◽  
Александр Юрьевич Цыганков ◽  
Абдусамад Аристанович Ахраров
Keyword(s):  
Anterior Chamber ◽  
Anterior Chamber Depth ◽  
Optical Power ◽  
Power Calculation ◽  
Group Iii ◽  
Group I ◽  
Retrospective Comparison ◽  
Group Ii ◽  
The Relationship

Aim. Determination of the relationship between the anterior chamber depth and the and accuracy of the IOL optical power calculating in the eyes with an axial length of less than 22 mm. Materials and methods. A total of 86 patients (133 eyes) with a short axis (from 18.54 to 21.98 (20.7 0.9) mm) were included in the study. Group I (n=40) consisted of patients with an ACD of less than 2, 5 mm. Group II (n=49) included patients with ACD from 2.5 to 2.9 mm Group III (n=44) included patients with ACD greater than 2.9 mm The calculation of the IOL optical power was carried out according to the formula SRK / T, retrospective comparison - according to the formulas Hoffer-Q, Holladay II, Olsen, Haigis and Barrett Universal II. Results. In group I, there were no significant differences when comparing MedAE for the six formulas (p0.05). The highest MedAE values ​​(0.51 and 0.49, respectively) and the smaller MNE range (-0.03 0.89 and -0.01 0.97, respectively) are shown for the formulas Haigis and Barrett Universal II. In group II, the MedAE for the Haigis formula was 0.45, for SRK / T and Olsen it was 0.59 and 0.66. For the Haigis formula, the lowest MNE value (0.05 0.69) is shown. In group III, no significant differences were found when comparing the average values ​​of MedAE (0.05). The lowest MedAE (0.17) and the best MNE values ​​(-0.01 0.58) are shown for the Haigis formula, while the SRK / T formula was characterized by the highest MedAE (0.37). In group II, the refractive index 0.25 and 0.50 D for the Haigis formula was significantly higher. Conclusion. For eyes with an ACD of less than 2.4 mm, none of the formulas showed a significant advantage, while with an ACD of 2.4-2.9 mm and higher, the use of the Haigis formula is recommended, and the SRK / T formula showed the worst result. The data obtained dictate the need to review existing standards for calculating the IOL optical power in patients with short eyes depending on ACD.

Intraocular lenses optic power calculation with seven formulas in short eyes

2021 ◽  
pp. 37-40
Author(s):  
K.B. Pershin ◽  
◽  
N.F. Pashinova ◽  
I.A. Likh ◽  
А.I. Tsygankov ◽  
...  
Keyword(s):  
Axial Length ◽  
Mean Absolute Error ◽  
Optical Power ◽  
Absolute Error ◽  
Intraocular Lenses ◽  
Power Calculation ◽  
Group I ◽  
The Mean ◽  
Group Ii ◽  
Axial Eye Length

Purpose. The choice of the optimal formula for calculating the IOL optical power in patients with an axial eye length of less than 20 mm. Material and methods.A total of 78 patients (118 eyes) were included in theprospective study. Group I included 30 patients (52 eyes) with short eyes (average axial eye length of 19.60 ± 0.42 (18.54-20.0) mm), group II consisted of 48 patients (66 eyes) with a axial length (22.75 ± 0.46 (22.0-23.77) mm. Various monofocal IOL models were used. The average follow-up period was 13 months. IOL optical power was calculated using the SRK/T formula, retrospective comparison - according to the formulas Hoffer-Q, Holladay II, Olsen, Haigis, Barrett Universal II and Kane. Results. In group I, the mean absolute error was determined for the formulas Haigis, Olsen, Barrett Universal II, Kane, SRK / T, Holladay 2 and Hoffer-Q (0.85; 0.78; 0.21; 0.17; 0.79; 0.73; 0.19 respectively). When comparing the formulas, significant differences were found for the formulas Hoffer-Q, Barrett Universal II and Kane in comparison with the formulas Haigis, Olsen, SRK / T and Holladay II (p <0.05) in all cases, respectively. In group I, the mean absolute error was determined for the formulas Haigis, Olsen, Barrett Universal II, Kane, SRK / T, Holladay 2 and Hoffer-Q (0.15; 0.16; 0.23; 0.10; 0.19; 0.23; 0.29 respectively) In group II, there were no significant differences between the studied formulas (p> 0.05). Conclusion. This paper presents an analysis of data on the effectiveness of seven formulas for calculating the IOL optical power in short (less than 20 mm) eyes in comparison with the normal axial length. The advantage of the Hoffer-Q, Barrett Universal II and Kane formulas over Haigis, Holladay 2, Olsen, and SRK / T is shown. Key words: cataract; hypermetropia; short eyes; calculation of the IOL optical power.

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