GaAs-AlGaAs V-grooved inner stripe (VIS) quantum-well wire (QWW) lasers grown by metalorganic chemical vapor deposition with different current blocking configurations, n-blocking on p-substrate (VIPS), p-n-p-n blocking on n-substrate (VI(PN)nS) and p-blocking on n-substrate (VINS) have been fabricated and characterized. The VIPS QWW lasers show the most stable characteristics with effective current confinement: one of the lasers shows fundamental transverse mode, lasing up to 5 mW/facet, typical threshold current of 39.9 mA at 818.5 mm, an external differential quantum efficiency of 24%/facet, and characteristic temperature of 92 K. The current tuning rate was almost linear at 0.031 mm/mA, and the temperature tuning rate was measured to be 0.14 nm/°C. Comparison of the light output versus current characteristics of the lasers with different current blocking configurations is presented here 相似文献
An efficient algorithm which detects and tracks a moving object is proposed. The global motion energy caused by camera movement is eliminated by finding the maximal matching position with the cross-correlation value between two consecutive frames using the spiral scanning technique. The region of a moving object is segmented exactly by combining the results of the temporal derivatives and edge map from one image, and the actual centroid of the moving object is determined as the mid-point of the cumulative distribution of the projection profile of the region 相似文献
A review of the development of the gel pond technology is presented. First, the emergence and growth of solar pond technology since the 1950's is described. The inherent problems encountered with the conventional salt gradient ponds are discussed, leading to the concept of the solar gel pond in which the salt gradient layer in the former is replaced by a transparent polymer gel. The major work in the first phase dealt with the experimental development of a polymer gel which met certain selection criteria. The criteria considered included transmissivity, stability of physical and chemical properties, high viscosity and other physical and optical properties. The gradual development of the polymer gel through an alternating process of testing and elimination and evaluation of relevant properties of the gel has been described. Modeling and optimization studies of the solar gel pond have been presented. Bansal and Kaushik's model for a salt gradient pond has been modified for a solar gel pond, and the results of the simulation are presented in a graphical form to serve as a quick reference for estimation of pond surface area, depth and flow rate for heat extraction depending on the extreme temperature required in the storage zone and the required heat load. Then, a cost-benefit economic analysis compares the economics of a solar gel pond with a conventional salt gradient pond. The construction of an experimental gel pond (18 m2) at The University of New Mexico is described, and the results of the study are summarized. Information on commercial scale ponds at Chamberino, New Mexico (110 m2), and in Albuquerque, New Mexico (400 m2), is provided. The review of the technology demonstrates the immense potential of the gel pond as a source of alternate energy for the years ahead. 相似文献
Abstract— Among various barrier‐rib manufacturing processes, the mold‐pattern‐transfer method has potential to reduce processing cost as well as the manufacture of high‐resolution pixels. In this study, the effects of major processing variables of the mold‐pattern‐transfer process on the formation of air‐trapped pores within barrier ribs were examined. The results indicated that with an optimum combination of the processing variables, barrier ribs without trapped defects can be produced, demonstrating the possibility of reducing the number of processing steps and costs of barrier ribs. 相似文献
Predicting remaining useful life (RUL) is crucial for system maintenance. Condition monitoring makes not only degradation data available for RUL estimation but also categorized health status data for health state identification. However, RUL prediction has been treated as an independent process in most cases even though potential relevance exists with health status detection process. In this paper, we propose a convolution neural network based multi-task learning method to reflect the relatedness of RUL estimation with health status detection process. The proposed method applied to the C-MAPSS dataset for aero-engine unit prognostics supported superior performances to existing baseline models.
Recently, watermarking based data transmission techniques using terrestrial digital TV signal have been proposed since they
are also cost-free and can overcome the limitations of GPS. However, in the previous watermarking based methods, the detection
accuracy is low and additional data rate is too low. Thus, we propose the throughput enhancement method by employing the TZCD-MBOK
watermarking technique in T-DMB system. By applying the proposed scheme to T-DMB, it allows additional data transmission for
disaster broadcasting and improves efficiency of data transmission in shadow region and indoor to mobile environment through
watermarking spread code. From the simulation results, we confirm the proposed watermarking scheme affected on the existing
T-DMB signal. Moreover, it was also confirmed that the system capacity increases as the power of additional watermarking signal
rose. The results of the paper can be applied to wireless multimedia digital broadcasting systems. 相似文献
Recently, many research projects and competitions have attempted to find an autonomous mobile robot that can drive in the
real world. In this article, we consider a path-planning method for an autonomous mobile robot that would be safe in a real
environment. In such a case, it is very important for the robot to be able to identify its own position and orientation in
real time. Therefore, we applied a localization method based on a particle filter. Moreover, in order to improve the safety
of such autonomous locomotion, we improved the path-planning algorithm and the generation of the trajectory so that it can
consider a region with a limited maximum velocity. In order to demonstrate the validity of the proposed method, we participated
in the Real World Robot Challenge 2010. The experimental results are given. 相似文献
Thermally induced errors reduce the accuracy in precision machining, and a great deal of research has been presented on compensation for these errors in machine tools. However, during the transition period after commencing or stopping spindle rotation, thermal deformation behavior is very complex. In particular, the y-directional movement of the vertical machining center cannot be explained by thermal expansion alone because of the relationship between deformation and temperature. Thermal bending that is generated from the thermal gradient in the structure causes this movement. In the research described in this paper, a theoretical explanation and an experimental verification is given for the particular behavior of spindle thermal deformation. As it is not easy to map the relationship of the compensation model, separation of the steady from the non-steady state in the mapping process is strongly recommended. 相似文献
In the present study, commercial pure Ti and Ti-6Al-4V alloy specimens with and without alkali and heat treatments were implanted
in the abdominal connective tissue of mice. Conventional stainless steel 316L was also implanted for comparison. After three
months, their biocompatibility was evaluated byin vitro andin vivo experiments. Surface structural changes of specimens due to the alkali treatment and soaking in Hank’s solution were analyzed
by XRD, SEM, XPS and AES. An apatite layer, which accelerates the connection with bone, was formed more easily on the alkali
treated specimens than the non-treated specimens. The number of macrophages, which is known to increase as the inflammatory
reaction proceeds, was much lower for the alkali and heat treated specimens than for the others. The average thickness of
the fibrous capsule formed around the implant was much thinner for the alkali and heat treated specimens than for the others. 相似文献