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Dong, J. (author), van Driel, W.D. (author), Zhang, Kouchi (author)This paper describes a new design concept of automatically diagnosing and compensating LED degradations in distributed solid state lighting (SSL) systems. A failed LED may significantly reduce the overall illumination level, and destroy the uniform illumination distribution achieved by a nominal system. To our knowledge, an automatic scheme to...journal article 2011
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van Driel, W.D. (author), Yazdan Mehr, M. (author), Zhang, Kouchi (author)Solid State Lighting (SSL) technologies and products are gradually pervading into our daily life. An SSL system is composed of a LED engine with a micro-electronics driver(s), integrated in a housing that also provides the optical, sensing and other functions. Knowledge of (system) reliability is crucial for not only the business success of the...conference paper 2014
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Yazdan Mehr, M. (author), van Driel, W.D. (author), Zhang, Kouchi (author)In this paper, progresses of color maintenance, also known as color shift, in solid-state lighting (SSL) systems are thoroughly reviewed. First, color shift is introduced and a few examples are given from different real-life industrial conditions. Different degradation mechanisms in different parts of the system are also explained. Different...review 2015
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Yazdan Mehr, M. (author), van Driel, W.D. (author), Zhang, Kouchi (author)A methodology, based on accelerated degradation testing, is developed to predict the lifetime of remote phosphor plates used in solid-state lighting (SSL) applications. Both thermal stress and light intensity are used to accelerate degradation reaction in remote phosphor plates. A reliability model, based on the Eyring relationship, is also...journal article 2015
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Yazdan Mehr, M. (author), Vollebregt, S. (author), van Driel, W.D. (author), Zhang, Kouchi (author)A graphene monolayer has been successfully coated on one side of a bisphenol-A-polycarbonate (BPA-PC) plate, used as a substrate for remote phosphor applications in light-emitting diode (LED)-based products. Using a photoresist transferring method, graphene sheet has been coated on BPA-PC plates. The results show that this graphene monolayer...journal article 2017
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Sun, B. (author), Fan, Xuejun (author), Li, Lei (author), Ye, H. (author), van Driel, W.D. (author), Zhang, Kouchi (author)This paper studies the interaction of catastrophic failure of the driver and LED luminous flux decay for an integrated LED lamp with an electrolytic capacitor-free LED driver. Electronic thermal simulations are utilized to obtain the lamp's dynamic history of temperature and current for two distinct operation modes: constant current mode (CCM...journal article 2017
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Sun, B. (author), Fan, Xuejun (author), Ye, H. (author), Fan, Jiajie (author), Qian, Cheng (author), van Driel, W.D. (author), Zhang, Kouchi (author)In this paper, an integrated LED lamp with an electrolytic capacitor-free driver is considered to study the coupling effects of both LED and driver's degradations on lamp's lifetime. An electrolytic capacitor-less buck-boost driver is used. The physics of failure (PoF) based electronic thermal simulation is carried out to simulate the lamp's...journal article 2017
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Van Der Sluis, Olaf (author), Iwamoto, Nancy (author), Qu, Jianmin (author), Yang, Shaorui (author), Yuan, C.A. (author), van Driel, W.D. (author), Zhang, Kouchi (author)Adhesion and delamination have been pervasive problems hampering the performance and reliability of micro-and nano-electronic devices. In order to understand, predict, and ultimately prevent interface failure in electronic devices, development of accurate, robust, and efficient delamination testing and prediction methods is crucial. Adhesion...book chapter 2018
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Yazdan Mehr, M. (author), van Driel, W.D. (author), De Buyl, Francois (author), Zhang, Kouchi (author)Degradation mechanisms of silicone plates under harsh environment conditions are studied in this investigation. Environmental degradation of silicone free form, used as secondary optics in Light Emitting Diode LED lighting lamps and luminaires or any other applications requiring high quality optics being used, has negative implications for the...journal article 2018
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Middelburg, L.M. (author), el Mansouri, B. (author), Poelma, René H. (author), van Zeijl, H.W. (author), Wei, J. (author), Zhang, Kouchi (author), van Driel, W.D. (author)The mechanical part of inertial sensors can be designed to have a large mechanical sensitivity, but also requires the transduction mechanism which translates this displacement. The overall system resolution in mechanical inertial sensors is dictated by the noise contribution of each stage and the magnitude of each sensitivity, see also Figure...conference paper 2018
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Yazdan Mehr, M. (author), Toroghinejad, M.R. (author), Karimzadeh, F. (author), van Driel, W.D. (author), Zhang, Kouchi (author)Reduction of intensity of light output is one of the most common degradation modes in light-emitting diode (LED) systems. It starts from the failure of the various components in the system, including the chip, the driver, and optical components (i.e. phosphorous layer). The kinetics of degradation in real life applications is relatively slow...journal article 2018
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Sun, Bo (author), Fan, Xuejun (author), van Driel, W.D. (author), Cui, Chengqiang (author), Zhang, Kouchi (author)In this study, we present a general methodology that combines the reliability theory with physics of failure for reliability prediction of an LED driver. More specifically, an integrated LED lamp, which includes an LED light source with statistical distribution of luminous flux, and a driver with a few critical components, is considered. The...journal article 2018
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Yazdan Mehr, M. (author), van Driel, W.D. (author), Zhang, Kouchi (author)Lumen depreciation is one of the major failure modes in light-emitting diode (LED) systems. It originates from the degradation of the different components within the system, including the chip, the driver, and the optical materials (i.e., phosphorous layer). The kinetics of degradation in real-life applications is relatively slow, and in most...book chapter 2018
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Huang, Cai (author), Wang, Yilin (author), Zhang, Xudong (author), Seminario Thulin, Andres (author), van Driel, Iris (author), Liu, Danyan (author), Droge, Jean Pierre (author)The coastal landscape of South Florida faces many challenges connected to climate change and urbanization. Sea level rise, loss of ecosystems, land subsidence, aquifer depletion are some of the issues that need serious attention. Landscape Approach Florida is showcasing results of a Landscape Architecture Design Lab where seven MSc-graduates...report 2019
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el Mansouri, B. (author), Middelburg, L.M. (author), Poelma, René H. (author), Zhang, Kouchi (author), van Zeijl, H.W. (author), Wei, J. (author), Jiang, H. (author), Vogel, J.G. (author), van Driel, W.D. (author)Commercially available gravimeters and seismometers can be used for measuring Earth’s acceleration at resolution levels in the order of ng∕Hz (where g represents earth’s gravity) but they are typically high-cost and bulky. In this work the design of a bulk micromachined MEMS device exploiting non-linear buckling behaviour is described, aiming...journal article 2019
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Yazdan Mehr, M. (author), van Driel, W.D. (author), Zhang, Kouchi (author)This paper investigates degradation and failure mechanisms of BPA-PC lenses in simulated harsh environment conditions. Exposure of secondary optics in Light Emitting Diode LED-based systems or any other similar applications to environmental stresses can adversely effect the performance and lifetime of products. This paper simulates a harsh...conference paper 2019
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el Mansouri, B. (author), van Driel, W.D. (author), Zhang, Kouchi (author)Nowadays many applications require optical detection of some sorts, ranging from civil to military fields. Depending on the optical source, each sensing element needs to have distinct properties with the spectral range at the top. Choices such as sensitivity and environment play an equally important role, if not more important. The properties of...book chapter 2020
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Khouzani, Mahdi Kiani (author), Bahrami, Abbas (author), Yazdan Mehr, M. (author), van Driel, W.D. (author), Zhang, Kouchi (author)This paper aims to investigate the synthesis, structure, and optical properties of SiO<sub>2</sub> @YAG:Ce core–shell optical nanoparticles for solid state lighting applications. YAG:Ce phosphor is a key part in white light emitting diodes (LEDs), with its main functionality being the generation of yellow light. Generated yellow light from...journal article 2020
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The inactivation mechanism of chemical disinfection against SARS-CoV-2: From MD and DFT perspectivesTan, C. (author), Gao, Chenshan (author), Zhou, Quan (author), van Driel, W.D. (author), Ye, H. (author), Zhang, Kouchi (author)Exploring effective disinfection methods and understanding their mechanisms on the new coronavirus is becoming more active due to the outbreak of novel coronavirus pneumonia (COVID-19) caused by severe acute respiratory coronavirus 2 (SARS-CoV-2). By combining molecular dynamics and first-principles calculations, we investigate the...journal article 2020
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Yazdan Mehr, M. (author), Bahrami, A. (author), van Driel, W.D. (author), Fan, X.J. (author), Davis, J.L. (author), Zhang, Kouchi (author)In this paper, degradation mechanisms of optical materials, used in the light emitting diode (LED)-based products, are reviewed. The LED lighting is one of the fastest technology shifts in human history. Lighting accounts for almost 20% of the global electrical energy use, inferring that replacement of traditional lighting sources with LEDs...journal article 2020