Papers by Keyword: DBR

Abstract: A plan view pattern control method for plate rolling called Mizushima Automatic Plan View Pattern Control System (MAS) or Dog Bone Rolling (DBR) was developed. In this method, the slab is given a non-uniform thickness profile in the width direction to obtain non-uniform elongation. In order to make the plate more rectangular under various rolling conditions, prediction of elongation is necessary. In this research, the influence of the dog-bone width (overly thick part at the slab width edge) on the fish-tail length (over-elongation at the slab end) is investigated. The fish-tail length increases as the dog-bone width increases in spite of the same dog-bone height. This phenomenon is related to the following behavior of the restriction of excessive elongation of the dog-bone: As the dog-bone width increases, the working length of restricting stress increases. Hence, restricting stress is released earlier and the rolling length for fish-tail formation increases. As a result, the fish-tail length increases. Therefore, for the prediction of plan view pattern, not only the dog-bone thickness, but also the dog-bone width should be considered.

Abstract: Traditional planning methods ignore the enterprise production capacity,the paper depend on the specific case in enterprise production to build a Production Scheduling System which applies Drum-Buffer-Rope theory. This system proposes the high output, low work in process and on time delivery as the goals, considering the bottleneck resource as well as providing the master production plan with the bottleneck resource, in addition employing the simulation optimization software-Simio to optimize the bottleneck process scheduling and raise the utilization ratio of bottleneck resource.

Abstract: Vertical structure of resonant cavity light-emitting diode (RCLED) is presented in this paper to further improve the photoelectric performance of the device. Modeling and 2D simulation have been proceeded with Crosslight APSYS[, the analysis and modeling software for semiconductor devices. Main results of the simulation are listed and discussed. The peak wavelength locates at about 550 nm with half-wave width of about 10 nm and its output power has been enhanced by 25% than the conventional one. The results prove that vertical RCLED is a considerable source for POF-based fiber communication.

Abstract: With the rapid increase of wind farms, a set of specific requirements have been established or are developing. The objective of these grid guidelines is to ensure wind farms not adversely affecting the power system. The control strategies and theories on low voltage ride through (LVRT) have been focused on for a long time, how to deal with the gird high voltage is seldom discussed. This paper introduces the main types of wind turbines, discusses the major grid requirements of high voltage ride through (HVRT). The capability of HVRT for current wind farms is introduced. The technology and its implementation of the HVRT of wind turbines are focused on. The technical feasibility to increase the capacity of HVRT for wind turbines and the cost are analyzed in detail. Finally a conclusion is achieved, that is installing DC chopper can help converters to realize HVRT.

Abstract: In wafer plants, product will be manufactured through same process with different setups and specifications. This special manufacturing process is described as re-entrant flows. In photo process of wafer manufacturing, products is also restricted to be processed through same machine in each reentrance to improve quality. This phenomenon will cause scheduling in photo process being complicated and is proved to be a NP-hard problem. This research develops a mathematical model for photo process to minimize the makespan. A feasible solution is achieved using DBR (drum-buffer-rope) method. The results are compared to the optimal solution that is achieved using branch and bound algorithm. Our results show that DBR based method achieves a near optimal solution in shorter time. The results also indicate that DBR method can be useful in production scheduling with resource constraints.

Abstract: In this paper, the basic theories and characteristics of distributed Bragg reflection (DBR) fiber laser and distributed feedback (DFB) fiber laser as hydrophone were described and analyzed; The interferometric demodulation technique of the underwater acoustic signals from fiber Bragg grating (FBG) hydrophone was discussed; And the theoretical experimental conclusions of the ultra-thin fiber Bragg grating hydrophone were introduced; Finally, the application in the torpedo homing field of the research on the ultra-thin fiber Bragg grating hydrophone were prospected.

Abstract: In this paper we discussed the relation between depth errors that happened in films growth and incidence angle variation on DBR reflectivity. We assume that there is 10% depth error in high and low index materials, and there are four plus one situations to be considered. Four are combinations of Hi +/- 10% error and Lo +/- 10% error, and no error. Our simulation results show that the depth error makes the reflective band shift and it almost doesn’t reduce reflectivity. The thickness error of +/- 10% in (Al0.4Ga0.6N/GaN) DBR structure (15 pairs) at 420nm was 42nm. A theoretical analysis using Transfer Matrix Mode with MATLAB software on the influence of layer thickness and incidence angle variation in vertical-cavity surface-emitting lasers with distributed Bragg reflectors (DBRs) on lasing wavelength is presented. It is shown that changing the thickness of the layers in the DBR mirror by only 10% is sufficient to produce shifts in the peak reflectance wavelength up to ± 20 nm (for a blue laser at 420nm). This could limit the precision of a desired wavelength, which is its reproducibility.

Abstract: In the fabrication of nitride-based laser, the cavity plays a vital role in order to enhance the fundamental modes while suppressing the higher order modes. The critical problem faced between the designer and the grower is the idealistic approach in the design laboratory, which more often cannot be met in the fabrication lines. This is because the design does not take into account the limitation in the growth chamber in achieving the targeted mirror thickness and material composition. This paper discusses methods of designing DBR mirrors for vertical cavity surface emitting GaN based lasers. Our design considers variance in the thickness and material composition of the mirrors. The simulation results are given for the investigation of several properties of DBR mirror, as well as a comparison of same types of symmetric DBR mirror.