Time filter

Source Type

Chang M.-S.,National Applied Research Laboratories NARL | Chen C.-R.,National Applied Research Laboratories NARL | Huang J.-D.,National Applied Research Laboratories NARL | Chen K.-H.,Da - Yeh University
Journal of Aeronautics, Astronautics and Aviation, Series A | Year: 2011

A small satellite equipped with a self-developed bus with the high-resolution optical remote sensing instrument (RSI) by integrating NSPO with the ITRC (Instrument Technology Research Center) of NARL was developed under the FORMOSAT-5 satellite program. Solar cell efficiency is temperature related. When the solar panel temperature is over 75°C, the efficiency degrades apparently. FORMOSAT-5 satellite solar power system is compacted due to the limited solar panel sizes at the current configuration. Reducing solar panel temperatures could help increase the availability of generated solar power. The objective of this thermal analysis is to reduce the solar array temperature by thermal control design. The solar panel temperatures with and without radiator under various thermal conditions including different beta angles, summer and winter seasons, solar panel configuration, and operating modes as supplied by electric power subsystem(EPS) designers are calculated. From different case studies and with radiators applied to the solar panels backside, the thermal control subsystem(TCS) predict solar panel flight temperature and support data to EPS subsystem predict the power margin. The power margin percentage will increase best to about 8.20% from EPS subsystem predictions and at this condition the maximum temperature can be reduced from 103°C to 95.7°C or about 7.3°C for hot condition. This improves the solar panel efficiency for hot condition.

Jan C.-M.,National Taiwan University | Lee Y.-H.,National Taiwan University | Wu K.-C.,National Taiwan University | Wu K.-C.,National Applied Research Laboratories NARL | And 2 more authors.
Optics Express | Year: 2011

A circularly polarized ellipsometer was developed to enable realtime measurements of the optical properties of materials. Using a four photo-detector quadrature configuration, a phase modulated ellipsometer was substantially miniaturized which has the ability to achieve a high precision detection limit. With a proven angular resolution of 0.0001 deg achieved by controlling the relative positions of a triangular prism, a paraboloidal and a spherical mirror pair, this new ellipsometer possesses a higher resolution than traditional complex mechanically controlled configurations. Moreover, the addition of an algorithm, FTA (fault tolerance algorithm) was adopted to compensate for the imperfections of the optomechanical system which can decrease system measurement reliability. This newly developed system requires only one millisecond or less to complete the measurement task without having to adopt any other modulation approach. The resolution achieved can be as high as 4x10-7 RIU (refractive index unit) which is highly competitive when compared with other commercially available instruments. Our experimental results agreed well with the simulation data which confirms that our quadrature-based circularly polarized ellipsometer with FTA is an effective tool for precise detection of the optical properties of thin films. It also has the potential to be used to monitor the refractive index change of molecules in liquids. © 2011 Optical Society of America.

Cheng C.-C.,National Taiwan University | Lin C.-Y.,National Taiwan University | Ho J.-H.,National Taiwan University | Shieh J.,National Taiwan University | And 6 more authors.
Journal of Mechanics | Year: 2010

We investigated the design parameters of a compact pot-like ultrasonic sensor which possesses a highly anisotropic beam pattern. As the sensor size is small due to its application constraint, the parameters are thus highly coupled to one another. We analyzed the respective effects of the parameters in the case where there is a vertical beam width reduction. The parameters investigated include resonant frequency, vibrating plate width-expanded angle, and ratio of thickness discontinuity of the vibrating plate. Numerical models developed by combining finite-element analysis and spatial Fourier transforms were adopted to predict the far-field radiating beam pattern of the various design configurations. The displacement distribution of the vibrating plate was measured using a microscopic laser Doppler vibrometer and the far-field pressure beam patterns were measured using a standard microphone in a semianechoic environment. The three configurations we used to validate the simulation model resulted in an H-V ratio of 2.67, 2.68 and 3.13, respectively which all agreed well with the numerical calculations. We found that by increasing the operating resonant frequency from 40kHz to 58kHz, the vertical far-field beam width of an ultrasonic sensor can be reduced by 31.62. We found that the vertical beam width can be significantly reduced when the ratio of the thickness discontinuity of the vibrating plate decreases from 1 to 0.4 and is incorporated with its optimal width-expanded angle of the vibrating plate. It appears that an ultrasonic sensor with this type of anisotropic beam pattern can be ideally adopted for today's automotive applications.

Chen Y.-C.,National Taiwan University | Chen T.-H.,National Taiwan University | Chien C.-J.,National Taiwan University | Chang W.-C.,National Taiwan University | And 6 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

Electret-based electrostatic devices have been used in the electro-acoustic field for decades. Recently, the improvement of its charge retention has been of interest for application to the field of smart materials. Hence, the flexible electret-based loudspeaker has become an important research topic for futuristic applications such as 3C (computers, communications and consumer electronics) and smart curtains. The volume velocity and the on-axis sound pressure level (SPL) of an electret loudspeaker are the key parameters of interest. To study the vibration characteristics of an electret diaphragm, a finite element analysis (FEA) was introduced to facilitate the design. To validate the finite element analysis (FEA) model, an out-of plane full-field non-destructive optical detection method which incorporates electronic speckle pattern interferometry (ESPI), was applied to determine the vibration mode shape of thin film. By driving the electret loudspeaker at different frequencies, a corresponding vibration mode of interest was detected with the ESPI set-up. Both the simulations and the experimental results obtained on the measurement platform are detailed in this paper. © 2010 SPIE.

Tsai W.-F.,National Applied Research Laboratories NARL | Chen B.,National Applied Research Laboratories NARL | Chang J.-Y.,National Applied Research Laboratories NARL | Lin F.-P.,National Applied Research Laboratories NARL | And 8 more authors.
International Journal of Automation and Smart Technology | Year: 2011

Taiwan frequently experiences natural disasters such as typhoons, floods, landslides, debris flows, and earthquakes. Therefore, the instant acquisition of high-definition images and topographic or spatial data of affected areas as disasters occur is crucial for disaster response teams and making emergency aid decisions. The National Applied Research Laboratories has implemented the project "development of near real-time, high-resolution, global earth observation 3D platform for applications to environmental monitoring and disaster mitigation." This developmental project integrates earth observation technologies, data warehousing, high-performance visualization displays, grids, and disaster prevention technology to establish a near real-time high-resolution three-dimensional (3D) disaster prevention earth observation application platform for Taiwan. The main functions of this platform include (1) integration of observation information, such as Formosat-2 satellite remote sensing, aerial photography, and 3D photography of disaster sites, to provide multidimensional information of the conditions at the affected sites; (2) disaster prevention application technologies, such as large-sized high-resolution 3D projection system, medium-sized active stereo projection systems, and small-sized personal computers with multiscale 3D display systems; (3) a 3D geographical information network platform that integrates data warehousing and cloud services, complies with the Open Geospatial Consortium (OGC) international standard for image data exchange and release processes, and includes image overlaying and added-value analysis of disasters; and (4) near real-time and automated simulation of image processing procedures, which accelerates orthophoto processing once raw data are received from satellites and provides appropriate images for disaster prevention decision-making within 3 to 6 h. This study uses the 88 Flood event of Typhoon Morakot in 2009, Typhoon Fanapi in 2011, and the 311 Earthquake of Japan in 2011 as examples to dissert the applications, functions and features of this platform for supporting disaster response and disaster recovery decision-making. © 2011 International Journal of Automation and Smart Technology.

Wang C.-H.,National Applied Research Laboratories NARL | Chen M.-H.,National Applied Research Laboratories NARL | Huang J.-D.,National Applied Research Laboratories NARL | Chen C.-R.,National Applied Research Laboratories NARL
Advanced Materials Research | Year: 2014

A numerical study of the effectiveness of phase change material (PCM) used on FORMOSAT-7 at the preliminary design phase is presented in this study. N-eicosane is used as the PCM for its melting temperature. To compare the performance of PCM, different messes of PCM are applied for high-power-dissipating component with short-duty-cycle. The results show that PCM can improve the thermal stability of component by not only moderating peak temperature for worst hot case but also preventing sudden temperature decrease when the power mode of component changed. However, mass addition of PCM reduces the duration of the maximum temperature and the minimum temperature due to the better thermal conductivity of solid phase. Therefore, an optimization of mass is suggested for the application of PCM. © (2014) Trans Tech Publications, Switzerland.

Wang C.-H.,National Applied Research Laboratories NARL | Huang J.-D.,National Applied Research Laboratories NARL | Chen C.-R.,National Applied Research Laboratories NARL
Procedia Engineering | Year: 2014

The FORMOSAT-7 (FS-7) satellite constellation collect atmospheric and ionospheric data primarily for operational weather forecasting and space weather monitoring to fulfill the needs of Taiwan, the US, and the rest of the world. Because of the relative high power consumption and limited temperature requirement, TriG receiver (TriGR) becomes a critical component for thermal control. A thermal model is developed to examine the temperature feasibility of TriGR at the preliminary design phase. Parametric studies including the sizes of radiators, the thicknesses and the lateral thermal conductances of honeycomb panels. Results show that the effect of thermal conduction is more significant than thermal radiation by comparing the influences of the lateral thermal conductance of honeycomb panel and the sizes of radiators. Moreover, it is found that both the thermal conductance between middle platform and wall panels, and the lateral thermal conductance of honeycomb panel are the main factors for thermal control of TriGR. A careful consideration for the bracket used between the middle platform and wall panels is therefore needed to guarantee the performance of it. © 2014 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.

National Applied Research Laboratories Narl | Date: 2013-03-18

A glitch-free data fusion method for combining multiple attitude solutions is disclosed, wherein a star camera is set as the master star camera. After acquiring attitude solutions from the star cameras, a rotation difference is calculated between a master attitude solution acquired from the master star camera and a slave attitude solution acquired from other star cameras. Then, a steady difference is acquired from the rotation difference via a low pass filter for correcting the slave attitude solution. When combining the corrected slave attitude solutions with the master attitude solution, the attitude glitches or attitude jumps, which occur while transitioning between data fusion configurations with different number of available attitude solutions, can be eliminated.

Loading National Applied Research Laboratories NARL collaborators
Loading National Applied Research Laboratories NARL collaborators