Assessment As with other courses, we were required to keep a reflective journal of our learning experiences during the course. This activity provided the opportunity to look back on the concepts covered and really reflect on the learning experience as a whole. Assessment is an ongoing process and can take many forms, but it is not without challenges. An effective online instructor develops assessment activities that enable the student to demonstrate, in a measurable way, mastery of the content material.
Electroluminescence as a phenomenon was discovered in by the British experimenter H.
In his publications, Destriau often referred to luminescence as Losev-Light. Destriau worked in the laboratories of Madame Marie Curiealso an early pioneer in the field of luminescence with research on radium. InBraunstein further demonstrated that the rudimentary devices could be used for non-radio communication across a short distance.
As noted by Kroemer  Braunstein "…had set up a simple optical communications link: Music emerging from a record player was used via suitable electronics to modulate the forward current of a GaAs diode. The emitted light was detected by a PbS diode some distance away.
This signal was fed into an audio amplifier and played back by a loudspeaker. Intercepting the beam stopped the music. We had a great deal of fun playing with this setup. After establishing the priority of their work based on engineering notebooks predating submissions from G.
George Craford a former graduate student of Holonyak, invented the first yellow LED and improved the brightness of red and red-orange LEDs by a factor of ten in Pearsall created the first high-brightness, high-efficiency LEDs for optical fiber telecommunications by inventing new semiconductor materials specifically adapted to optical fiber transmission wavelengths.
These red LEDs were bright enough only for use as indicators, as the light output was not enough to illuminate an area. Readouts in calculators were so small that plastic lenses were built over each digit to make them legible.
Later, other colors became widely available and appeared in appliances and equipment. In the s commercially successful LED devices at less than five cents each were produced by Fairchild Optoelectronics.
These devices employed compound semiconductor chips fabricated with the planar process invented by Dr. Jean Hoerni at Fairchild Semiconductor. Nakamura, Akasaki, and Amano were awarded the Nobel prize in physics for their work. In  and processes for growing gallium nitride GaN LEDs on silicon were successfully demonstrated.
As ofsome manufacturers are using SiC as the substrate for LED production, but sapphire is more common, as it has the most similar properties to that of gallium nitride, reducing the need for patterning the sapphire wafer.
Patterned wafers are known as epi wafers. Toshiba has stopped research, possibly due to low yields. Epitaxy or patterned sapphire can be carried out with Nanoimprint lithography.
In this device a Y 3Al 5O Ce known as " YAG " cerium doped phosphor coating on the emitter absorbs some of the blue emission and produces yellow light through fluorescence.
The combination of that yellow with remaining blue light appears white to the eye. However, using different phosphors fluorescent materials it also became possible to instead produce green and red light through fluorescence.
The resulting mixture of red, green and blue is not only perceived by humans as white light but is superior for illumination in terms of color renderingwhereas one cannot appreciate the color of red or green objects illuminated only by the yellow and remaining blue wavelengths from the YAG phosphor.
The latest research and development has been propagated by Japanese manufacturers such as PanasonicNichiaetc. SamsungSolsticeKingsun, and countless others. This led to relatively high-power white-light LEDs for illumination, which are replacing incandescent and fluorescent lighting.
It can be encapsulated using resin, silicone, or epoxy containing powdered Cerium doped YAG phosphor. Encapsulation is performed after probing, dicing, die transfer from wafer to package, and wire bonding or flip chip mounting, perhaps using Indium tin oxidea transparent electrical conductor.
Remote phosphor LED light bulbs may have behind the plastic cover a white plastic reflector. Others shape the remote phosphor as a dome, or sphere, and place it atop a single PCB containing blue LEDs; this assembly may be behind a frosted glass or plastic cover.
The PCB is often installed atop a pillar, which is lined with white plastic. Working principle[ edit ] The inner workings of an LED, showing circuit top and band diagram bottom A P-N junction can convert absorbed light energy into a proportional electric current.
The same process is reversed here i. This phenomenon is generally called electroluminescencewhich can be defined as the emission of light from a semiconductor under the influence of an electric field. The charge carriers recombine in a forward-biased P-N junction as the electrons cross from the N-region and recombine with the holes existing in the P-region.
Free electrons are in the conduction band of energy levels, while holes are in the valence energy band. Thus the energy level of the holes is less than the energy levels of the electrons.• What format would you like teacher candidates to use for their reflections (e.g., email, a physical notebook, a journal kept in a word-processing program, a blog)?
• When and how will you review teacher candidates’ reflections to provide the standards are suggested as a focus of . written reflective narrative on practice using various strat-egies such as education, a facilitator or guide, and/or a participants indicated that a format or structure for the writing exercise enhanced one’s ability to practitioners’ views on how reflective practice has Journal For Nurses in Staff Development timberdesignmag.com 3.
The Way of the Journal: A Journal Therapy Workbook for Healing [Kathleen Adams] on timberdesignmag.com *FREE* shipping on qualifying offers. In The Way of the Journal, therapist and author Kathleen Adams, M.A. teaches her trademark approach to using reflective writing as a therapeutic process.
Adams' ten-step quick and easy method was created to provide sexual abuse survivors and dissociative clients. Purpose of the Journal Entries.
Every excellent lawyer is a self-reflective practitioner. A self-reflective practitioner is one who develops techniques for consciously learning from his or her experiences. Students suggested to reduce the number of required journal entries (e.g., completing one journal entry every two weeks or when reflections are needed) or to use the journal entries as a means of self-reflection only without instructors' evaluation.
From left, Lisa Jahnke, Heather Mlsna, Karla Paterson and Carrie Pearson listen during group introductions. (Journal photo by Corey Kelly. Participants could focus on self-reflective work, or.