It has been several years since InGaN/GaN light-emitting diodes (LEDs) on nonpolar and semipolar orientations were first demonstrated. Prominent performance and inherent potential of these ...crystallographic orientations have been revealed as bulk-GaN substrates of arbitrary orientations became available for epitaxial device growth. At this point in time, we intend to survey the progress made to date and prospect the future requirements for further device improvements. The discussion begins with a historical background: how nonpolar/semipolar orientations were introduced to III-nitride LEDs and why they are beneficial. The discussion then provides information on elementary crystallography and piezoelectricity in addition to the electronic band structure of wurtzite crystals. Later in this paper, LED reports are collected to develop comprehensive knowledge of the past research efforts and trends. Nonpolar and semipolar orientations provide not only high LED performances, e.g., optical output power and wavelength ranges, but also unique functions, e.g., polarized light emission, which will explore new fields of applications.
Based on the rotational symmehy of the principal axes of X100, Y010 and Z001, 72 possible combinations of the five slips on {110} planes based on Taylor's formidable restriction rule of the five ...slips are calculated among three kinds of intersections of two {110} planes on 111 direction in bcc metal. Crystal rotation is carried out by only one solution among the 72 by the minimum total slip at every strain and simulates properly lengthy of accumulated researcher's experimental results such as the three stable orientations of bcc metal in rolling {112} 110 , {11 11 8} 4 4 11 and {100} 011 .
BIRDS-2, the second generation of the Joint Global Multi-Nation Birds (JGMNB) project is a constellation of 1U CubeSats from Laboratory of Spacecraft Environment Interaction Engineering (LaSEINE), ...Kyushu Institute of Technology, Japan. The BIRDS-2 project consists of three identical 1U built by a group of students from four nations; Japan, Malaysia, Philippines, and Bhutan. It consists of 6 missions; Camera, Automatic Radio Packet Service-Digipeater (APRS-DP), Store and Forward (S&F), COTS GPS, Anisotropic Magneto Resistance Magnetometer (AMR-MM), and detection of single-event latch-up (SEL). The objective of BIRDS-2 is to provide an opportunity to learn the entire satellite system cycle, to lay down the foundation of the sustainable space program, and to create international networks of the ground station to assist the infant space program of the participating country. A total of 11 members learns the satellite development in a lean concept of 30m radius of the work area. The paper will describe the bus system of the BIRDS-2 CubeSats and the development process throughout the one year and three months of the project timeline. Completion of BIRDS-2 flight models remarks the successful design of the CubeSats bus system and waiting for the launch and deploy from International Space Station (ISS) around 3rd quarter of this year.
An international project has started to establish an International organization for standardization standard for the electrostatic discharge (ESD) on the solar array panel. For the ESD ground test of ...satellite solar panel, it is important to understand the characteristics of a primary arc discharge. A solar array coupon made of triple-junction cells is used to understand the primary arc characteristics. In particular, the experiment focuses on the measurement of the propagation speed of plasma generated by the primary arc. The plasma propagation is analyzed using images captured by a high-speed video camera and an image intensified camera. The plasma propagation speed derived from discharge images decreases in proportion to the inverse of the square root of time. The arc current waveform assuming the decreasing speed agreed with the experiment waveform very well.
This paper presents an approach to design a feasible and reliable monopole antennae deployment mechanism for CubeSat applications. Nano-satellite has faced problems in designing antennae deployment ...system due to space and deployment mechanism constraints. In BIRDS-2 CubeSat, the nichrome wire burning release mechanism was used when activated, it will be heated up and thermally cut through fishing line, allowing the two monopole antennas to be deployed on +Y board and at +Z axis direction of the satellite. These antennae involved amateur radio frequencies in UHF and VHF bands due to its low cost and high accessibility by the end users. The UHF frequency band was used for command uplink, mission, telemetry, and CW beacon downlink whilst the VHF frequency band was used specifically for APRS-DP/S&F-RDC mission for both uplink and downlink. In order to achieve the effectiveness of the BIRDS-2 CubeSat communication system agreed with the link budget estimation, the dimensions of antennae on the CubeSat structure depend on the required gain and operating frequency. The paper discusses detailed results of mechanical and electrical interfaces of the two monopole antennas deployment mechanism with the satellite body and the nichrome wire burning release mechanism analysis. The tests results of the mechanism were analyzed particularly on the deployment time and the nichrome wire temperature differences.
Excitation of the A-band low-lying electronic states in the methyl halides, CH(3)I, CH(3)Br, CH(3)Cl, and CH(3)F, has been investigated for the (n-->sigma*) transitions, using electron energy loss ...spectroscopy (EELS) in the range of 3.5-7.5 eV. For the methyl halides, CH(3)I, CH(3)Br, and CH(3)Cl, three components of the Q complex ((3)Q(1), (3)Q(0), and (1)Q(1)) were directly observed, with the exception of methyl fluoride, in the optically forbidden EELS experimental conditions of this investigation. The effect of electronic-state curve crossing emerged in the transition probabilities for the (3)Q(0) and (1)Q(1) states, with spin-orbit splitting observed and quantified against results from recent ab initio studies.
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