A comparison of blue-light transmissions through blue-control lenses
- Authors: Carlson, Anthony S.
- Date: 2019
- Subjects: Blue light , Transmission , Reflective coatings
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/405562 , uj:34061 , Citation: Carlson AS. A comparison of blue-light transmissions through blue-control lenses. Afr Vision Eye Health. 2019;78(1), a497. https://doi. org/10.4102/aveh.v78i1.497 , ISSN: (Online) 2410-1516
- Description: Abstract: Background: Many people are exposed to blue light through devices such as cellular phones, tablets and computers. Such light may affect us depending on its wavelength and blue-control lenses are now frequently used, thus influencing our daily lives. Aim: This study provides an analysis of the transmissions of blue light through 10 lenses with different blue-control coatings. Setting: The study was conducted at the Department of Optometry, University of Johannesburg, South Africa. Methods: Transmission curves of 10 lenses with different blue-control reflective coatings were compared. A control lens (the achromatic lens) was also included. The Cary Varian 5000 photo spectrophotometer from the Department of Physics at the University of Johannesburg was used to measure the spectral transmittances of these lenses with refractive indices ranging from 1.5 to 1.6. The geometric centre of each lens was aligned with the measuring axis of the spectrophotometer and spectral transmittance between 300 nm and 500 nm was measured. Results: For the 10 lenses studied, the transmission of wavelengths below 460 nm varied from 48% to 69% and for wavelengths between 460 nm and 500 nm from 33% to 55%. The differences between lenses were greater than 20%. If we changed the range of transmission to between 480 nm and 500 nm, the percentage transmitted varied from approximately 71% to 83% to give about a 12% difference between all the lenses. Conclusion: Not all lenses displayed similar transmissions of blue light and different manufacturers do not agree as to what percentage of blue light should be reflected or transmitted.
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- Authors: Carlson, Anthony S.
- Date: 2019
- Subjects: Blue light , Transmission , Reflective coatings
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/405562 , uj:34061 , Citation: Carlson AS. A comparison of blue-light transmissions through blue-control lenses. Afr Vision Eye Health. 2019;78(1), a497. https://doi. org/10.4102/aveh.v78i1.497 , ISSN: (Online) 2410-1516
- Description: Abstract: Background: Many people are exposed to blue light through devices such as cellular phones, tablets and computers. Such light may affect us depending on its wavelength and blue-control lenses are now frequently used, thus influencing our daily lives. Aim: This study provides an analysis of the transmissions of blue light through 10 lenses with different blue-control coatings. Setting: The study was conducted at the Department of Optometry, University of Johannesburg, South Africa. Methods: Transmission curves of 10 lenses with different blue-control reflective coatings were compared. A control lens (the achromatic lens) was also included. The Cary Varian 5000 photo spectrophotometer from the Department of Physics at the University of Johannesburg was used to measure the spectral transmittances of these lenses with refractive indices ranging from 1.5 to 1.6. The geometric centre of each lens was aligned with the measuring axis of the spectrophotometer and spectral transmittance between 300 nm and 500 nm was measured. Results: For the 10 lenses studied, the transmission of wavelengths below 460 nm varied from 48% to 69% and for wavelengths between 460 nm and 500 nm from 33% to 55%. The differences between lenses were greater than 20%. If we changed the range of transmission to between 480 nm and 500 nm, the percentage transmitted varied from approximately 71% to 83% to give about a 12% difference between all the lenses. Conclusion: Not all lenses displayed similar transmissions of blue light and different manufacturers do not agree as to what percentage of blue light should be reflected or transmitted.
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Development of an electric drive train for cycles as a sustainable means of transportation for a green environment
- Chinguwa, Simon, Nyemba, Wilson R., Ngondo, Emmanuel, Mbohwa, Charles
- Authors: Chinguwa, Simon , Nyemba, Wilson R. , Ngondo, Emmanuel , Mbohwa, Charles
- Date: 2019
- Subjects: Electric drive train , Manufacture , Transmission
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/295143 , uj:32130 , Citation: Chinguwa, S. et al. 2019. Development of an electric drive train for cycles as a sustainable means of transportation for a green environment.
- Description: Abstract: A reliable and sustainable means of human transportation is vital for the world’s increasing pollution emissions and congestions on the motorways. The research aimed at and focused on developing an affordable electric drive train for cycles using the principle of Continuously Variable Transmission (CVT) to provide an interminable number of speed ratios by varying the pulley diameters. The planetary gears designed and installed within the CVT chamber provided a locking mechanism for the ring gear to provide forward transmission to the rear wheel where motion was stepped up through an open differential gear to propel the cycle forward. For stability and ease of manufacture and assembly, a tricycle concept was chosen and developed as a sustainable and alternative means of transportation. The developed electric drive train provides a ‘green’ and affordable means of human transportation in a world geared towards the elimination of pollution.
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- Authors: Chinguwa, Simon , Nyemba, Wilson R. , Ngondo, Emmanuel , Mbohwa, Charles
- Date: 2019
- Subjects: Electric drive train , Manufacture , Transmission
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/295143 , uj:32130 , Citation: Chinguwa, S. et al. 2019. Development of an electric drive train for cycles as a sustainable means of transportation for a green environment.
- Description: Abstract: A reliable and sustainable means of human transportation is vital for the world’s increasing pollution emissions and congestions on the motorways. The research aimed at and focused on developing an affordable electric drive train for cycles using the principle of Continuously Variable Transmission (CVT) to provide an interminable number of speed ratios by varying the pulley diameters. The planetary gears designed and installed within the CVT chamber provided a locking mechanism for the ring gear to provide forward transmission to the rear wheel where motion was stepped up through an open differential gear to propel the cycle forward. For stability and ease of manufacture and assembly, a tricycle concept was chosen and developed as a sustainable and alternative means of transportation. The developed electric drive train provides a ‘green’ and affordable means of human transportation in a world geared towards the elimination of pollution.
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Novel heuristic and SVM based optimization algorithm for improving distribution feeder performance
- Jordaan, J. A., Nicolae, Dan-Valentin, Jimoh, A. A.
- Authors: Jordaan, J. A. , Nicolae, Dan-Valentin , Jimoh, A. A.
- Date: 2012
- Subjects: Transmission , Electric transformer
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/17526 , uj:15895 , Citation: Jordaan, J.A., Nicolae, D.V. & Jimoh, A.A. 2012. Novel heuristic and SVM based optimization algorithm for improving distribution feeder performance. In: The 2012 International Joint Conference on Neural Networks. DOI;10.1109/IJCNN.2012.6252616-5. , DOI;10.1109/IJCNN.2012.6252616
- Description: Abstract: Secondary distribution networks generally perform as well as its LV feeders are performing. The main problem that a feeder is experiencing would be the load unbalancing due to the stochastic nature of its individual single-phase loads: larger losses in certain phases accompanied by bad voltage regulation and voltage unbalance. In order to address this problem, it may be economical to install apparatus to automatically balance or partially balance the loads progressing from the end of the feeder towards the front using smart devices based on a three-ways switch selector and an artificial intelligence algorithm to minimize the neutral current. The main idea behind this paper is therefore to keep the three phases progressively balanced along the whole length of the line. A Support Vector Machines (SVM) implementation and a heuristic method are presented as the numerical algorithms
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- Authors: Jordaan, J. A. , Nicolae, Dan-Valentin , Jimoh, A. A.
- Date: 2012
- Subjects: Transmission , Electric transformer
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/17526 , uj:15895 , Citation: Jordaan, J.A., Nicolae, D.V. & Jimoh, A.A. 2012. Novel heuristic and SVM based optimization algorithm for improving distribution feeder performance. In: The 2012 International Joint Conference on Neural Networks. DOI;10.1109/IJCNN.2012.6252616-5. , DOI;10.1109/IJCNN.2012.6252616
- Description: Abstract: Secondary distribution networks generally perform as well as its LV feeders are performing. The main problem that a feeder is experiencing would be the load unbalancing due to the stochastic nature of its individual single-phase loads: larger losses in certain phases accompanied by bad voltage regulation and voltage unbalance. In order to address this problem, it may be economical to install apparatus to automatically balance or partially balance the loads progressing from the end of the feeder towards the front using smart devices based on a three-ways switch selector and an artificial intelligence algorithm to minimize the neutral current. The main idea behind this paper is therefore to keep the three phases progressively balanced along the whole length of the line. A Support Vector Machines (SVM) implementation and a heuristic method are presented as the numerical algorithms
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Phase load balancing in the secondary distribution network using fuzzy logic
- Siti, M. W., Jimoh, A. A., Nicolae, Dan-Valentin
- Authors: Siti, M. W. , Jimoh, A. A. , Nicolae, Dan-Valentin
- Date: 2007
- Subjects: Circuit breakers , Transmission
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/20257 , uj:16084 , ISBN:078038606x , Citation: Siti, M.W., Jimoh, A.A. & Nicolae, D.-V. 2007. Phase load balancing in the secondary distribution network using fuzzy logic. IEEE AFRICON’07, Windhoek, Namibia, 26-28 September, 2007:1-7. DOI:10.1109/AFRCON.2007.4401569
- Description: Abstract: The electrical network system is to ensure that an adequate supply is available to meet the estimated load of the consumers in both the near and more distant future. This must of course, be done for minimum possible cost consistent with satisfactory reliability and quality of the supply. In order to avoid excessive voltage drop and minimize loss, it may be economical to install apparatus to balance or partially balance the loads. It is believed that the technology to achieve an automatic load balancing lends itself readily for the implementation of different types of algorithms for automatically rearranging the connection of consumers on the low voltage and of a feeder for optimal performance. In this paper the fuzzy logic is been implemented to balance the load in the secondary part of the transformer
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- Authors: Siti, M. W. , Jimoh, A. A. , Nicolae, Dan-Valentin
- Date: 2007
- Subjects: Circuit breakers , Transmission
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/20257 , uj:16084 , ISBN:078038606x , Citation: Siti, M.W., Jimoh, A.A. & Nicolae, D.-V. 2007. Phase load balancing in the secondary distribution network using fuzzy logic. IEEE AFRICON’07, Windhoek, Namibia, 26-28 September, 2007:1-7. DOI:10.1109/AFRCON.2007.4401569
- Description: Abstract: The electrical network system is to ensure that an adequate supply is available to meet the estimated load of the consumers in both the near and more distant future. This must of course, be done for minimum possible cost consistent with satisfactory reliability and quality of the supply. In order to avoid excessive voltage drop and minimize loss, it may be economical to install apparatus to balance or partially balance the loads. It is believed that the technology to achieve an automatic load balancing lends itself readily for the implementation of different types of algorithms for automatically rearranging the connection of consumers on the low voltage and of a feeder for optimal performance. In this paper the fuzzy logic is been implemented to balance the load in the secondary part of the transformer
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