Browsing by Author "Wang, C"

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A magazine assignment heuristic for robotic assembly using the dynamic pick-and-place approach
(1997-03-01)
Wang, C
;
Ho, LH
;
Fu, HI
;
Su, YC
;
工業工程與管理學系
Robotic assembly cells consist principally of an assembly table: a supply magazine, and a Cartesian robot where the robot picks up assigned components from the magazine and places them in prearranged locations on the assembly table. The major concern in industry is to optimize robot traveling time so that a shorter assembly cycle time can be achieved. Three factors directly affecting assembly efficiency are: (1) robot motion control, (2) the sequence for placing the individual component on the assembly board, and (3) the corresponding magazine slot location from which the components must be selected. This paper proposes a magazine assignment heuristic coupled with dynamic pick-and-place (DPP) robot motion control to improve assembly efficiency. Simulation results indicate that our magazine assignment heuristic, with DPP robot motion control, always surpasses the same magazine assignment heuristic applied to the traditional fixed pick-and-place (FPP) robot motion control.
A magazine assignment heuristic for robotic assembly using the dynamic pick-and-place approach
(1997-03-01)
Wang, C
;
Ho, LH
;
Fu, HI
;
Su, YC
;
工業工程與管理學系
Robotic assembly cells consist principally of an assembly table: a supply magazine, and a Cartesian robot where the robot picks up assigned components from the magazine and places them in prearranged locations on the assembly table. The major concern in industry is to optimize robot traveling time so that a shorter assembly cycle time can be achieved. Three factors directly affecting assembly efficiency are: (1) robot motion control, (2) the sequence for placing the individual component on the assembly board, and (3) the corresponding magazine slot location from which the components must be selected. This paper proposes a magazine assignment heuristic coupled with dynamic pick-and-place (DPP) robot motion control to improve assembly efficiency. Simulation results indicate that our magazine assignment heuristic, with DPP robot motion control, always surpasses the same magazine assignment heuristic applied to the traditional fixed pick-and-place (FPP) robot motion control.
Characteristics of MOCVD- and MBE-grown InGa(N)As VCSELs
(2005-08-01)
Yang, HPD
;
Lu, C
;
Hsiao, R
;
Chiou, C
;
Lee, C
We report our results on InGaNAs/GaAs vertical-cavity surface-emitting lasers (VCSELs) in the 1.3 mu m range. The epitaxial structures were grown on (10 0) GaAs substrates by metalorganic chemical vapour deposition (MOCVD) or molecular beam epitaxy (MBE). The nitrogen composition of the InGa(N)As/GaAs quantum-well (QW) active region is 0-0.02. The long-wavelength (up to 1.3 mu m) room-temperature continuous-wave (RT CW) lasing operation was achieved for MBE- and MOCVD-grown VCSELs. For MOCVD-grown devices with n- and p-doped distributed Bragg reflectors (DBRs), a maximum optical output power of 0.74 mW was measured for In(0.36)Ga(0.64)N(0.006)AS(0.994)/GaAs VCSELs. A very low J(th) of 2.55 kA cm(-2) was obtained for the InGaNAs/GaAs VCSELs. The MBE-grown devices were made with an intracavity structure. Top-emitting multi-mode 1.3 mu m In0.35Ga0.65N0.02As0.98/GaAs VCSELs with 1 mW output power have been achieved under RT CW operation. A J(th) of 1.52 kA cm-2 has been obtained for the MBE-grown In0.35Ga0.65N0.02As0.98/GaAs VCSELs, which is the lowest threshold current density reported. The emission characteristics of the InGaNAs/GaAs VCSELs were measured and analysed.
Effect of thin film coating of Au on joint strength in Invar-Invar packages
(1996-11-01)
Wang, SC
;
Wang, CM
;
Wang, C
;
Chang, HL
;
Tu, YK
The effect of a thin film coating of Au on the joint strength, weld width, and penetration depth in laser welding techniques for Invar-Invar packages is investigated experimentally. It is found that the joint strength, weld width, and penetration depth are strongly dependent on the coating of Au thickness on the Invar material. The welded joints with thick Au coating show narrower weld width, shallower penetration, and hence less joint strength than those of the packages with thin Au coating. The increase in both the thermal conductivity and the vapor volume in the welded joints as the coating of Au thickness increases are the possible mechanisms for the reduction. Detailed knowledge of the effect of thin film coatings of Au on the welded materials, which gives both the highest joint strength and good adhesion, is essential for practical design and fabrication of reliable optoelectronic packaging.
Magneto-optic imaging of proton-irradiated high T-c superconducting thin films: A revisit of J(c)(T) functional and flux pinning enhancement
(2001-10-10)
Wang, C
;
Seo, HW
;
Su, CJ
;
Wang, YH
;
Chen, QY
We have performed systematic quantitative measurements of the critical current density J(c)(B,T) for YBCO thin films proton-irradiated to various dosages using the MOI technique. Results for external magnetic fields up to 400Oe and temperature ranging from 5 to 80 K are T resented for a 600 nm thick YBCO film irradiated by proton up to a dosage of 10(16) cm(-2) at 500 keV. While no significant differences were observed for T > 50K, the J(c) values consistently increased with the increasing external field for T < 50 K.
Performances and characteristics of a prototype symmetric hybrid adjustable phase undulator
(1997-11-11)
Hwang, CS
;
Chang, CH
;
Fan, TC
;
Lin, FY
;
Wang, C
In this work, we construct and measure a prototype symmetric Hybrid Adjustable Phase Undulator (HAPU) with nine poles to compare phase change and gap change in terms of their features and performances. HAPU can also provide the different characteristics between the pure and hybrid adjustable phase undulator. The HAPU has been installed in the Synchrotron Radiation Research Center (SRRC) storage ring to test the performance of the beam dynamics and photon flux behavior. A three-orthogonal Hall probe and a long-loop-coil measurement system are also implemented to take the field measurements. The multipole field and electron trajectory correction are made by shimming, the magic finger, and the active end pole coil corrector. After the field measurements, the vertical integral strength of HAPU is markedly smaller than that of the Hybrid Adjustable Gap Undulator (HAGU) and confirm that no obvious distinction arises between HAPU and HAGU in terms of the spectrum flux. The electron beam dynamic performance in the storage ring indicates that the vertical tune shift of HAPU is three times smaller than that of HAGU. Meanwhile, the energy dynamic tuning with the digital global feedback turned on, the photon position and flux in the bending chamber beam line is invariant. In addition, the injection efficiency remains unaffected at any phase position and the electron beam lifetime does not change when HAPU is in the dynamic tuning.
Photon spectrum characteristics and magnetic field performance of the prototype hybrid symmetry undulator magnet in SRRC
(1997-10-01)
Hwang, CS
;
Chang, CH
;
Lin, FY
;
Fan, TC
;
Yeh, S
A prototype Halbach hybrid magnet structure undulator with period of 10 cm was used to achieve a high magnetic field. A nearly sinusoidal magnetic field strength of 0.964 Tesla at 24 mm gap was achieved. The magnetic field was also designed and calculated using the magneto-static 3-D code of ''TOSCA''. According to those results, the field uniformity was better than 0.1% in the field rolloff range of x = +/-10 mm at 24 mm gap. The real field profile was measured to find the magnetic field behavior and the photon energy spectrum characteristics. In addition, field distributions obtained from the field measurement and simulation were used to calculate the photon spectrum characteristic. After the multipole and spectrum shimming, the good field region was controlled within 100 G.cm in the range of -2 cm less than or equal to x less than or equal to 2 cm to increase the dynamic aperture. A maximum phase error around 5.5 degrees was achieved and then maintained a high flux in the higher harmonic spectrum. The photon flux intensity is very close to the value of the ideal field simulation, which is about 10(15) photons/sec/100mA/0.1%BW. The energy range of the first harmonic ranges from 5.2 to 220 eV and the higher harmonic energy can reach 1 KeV. The electron trajectory deviation was controlled to within 5 mu m to maintain a constant optical axis and satisfy the beam dynamic requirements.
System development and performance investigation of mobile ad-hoc networks in vehicular environments
(2005)
Chuang, BW
;
Tarng, JH
;
Lin, J
;
Wang, C
;
傳播研究所
This paper presents the methodology of implementations and performance measurements of our mobile ad-hoc network (MANET) platforms. The work is prompted by the lack of published results concerning the issues associated with the implementation of MANET facilities on actual wireless networks, as opposed to results of simulation experiments. Our MANET is developed based on the settled IEEE 802.11b technology operating in the ad-hoc mode. The opportunity driven multiple access (ODMA), which is developed by IWICS Inc., is implemented on the platform and its performance has been examined through field tests along city streets. Based on the measurement results, ODMA-based MANET facilities are able to provide satisfactory wireless communication services in vehicular environments. The minimum data throughput of 20kBytes/sec could be guaranteed in our testbed.
The construction of a 9-pole prototype for SRRC U-10 undulator
(1996-07-01)
Chang, CH
;
Chang, LH
;
Chen, HH
;
Fan, TC
;
Hwang, CS
A 9-pole undulator prototype with a magnetic period length of 10 cm was designed and constructed to examine the mechanical and magnetic field performance. The hybrid permanent magnet structure was optimized by using 2D ''PANDIRA'' and 3D ''TOSCA'' magnetostatic codes. A half period magnet model was also fabricated to verify the magnetic Period length field strength on-axis and the transverse field roll-off within 0.1 % in the good field region of +/- 10 mm at a minimum gap of 22 mm. The end pole configurations, as equipped with either two tunable permanent magnetic rotators or steering coil correctors were designed for minimizing the deviation of the magnetic field strength integrals. The magnet structures were mounted bn a 2 meter long C-frame support structure in which the gap could be moved in parallel and phase motion. The field characteristics, and measurement results between the adjustable gap undulator (AGO) and the hybrid adjustable phase undulator (APU) were also presented.