Intensity surface stretching technique for contrast enhancement of digital photography

In this paper we propose a contrast enhancement technique which stretches the intensity surfaces of an image to improve the quality of a digital photo. The proposed method enhances the contrast of an image by stretching the intensity surface of the original image to the maximum range of the output image. This is done in proportion to the distances between the original intensity surface, and the upper and lower intensity surfaces respectively. The upper and lower intensity surfaces are generated adaptively from the original intensity surface by gaussian smoothing and gamma transform. In our experiments, digital color images in a variety of illumination conditions were used, and the proposed method was compared with other algorithms such as histogram stretching, histogram equalization, gamma correction, and retinex. From the results of the experiments, it was proven that the proposed algorithm further enhanced the contrast more than other methods and resulted in a more natural image without deterioration of gradation.

目标视场位置对经纬仪测角精度的影响

通过对经纬仪的内同步原理介绍,分析了CCD相机在测量中的误差影响因素,采用校飞试验数据作差结果验证了目标视场位置及运动速度对测角精度的影响。结果表明:目前采用的同步模式会导致测角精度下降,且目标偏离中心越远(脱靶量大),误差越大。针对内同步带入的测角误差,给出了软硬件的误差修正方法,以测量数据验证了二阶多项式拟合修正方法的有效性。     

A 20 GHz Steerable Array Antenna Using 3-bit Dielectric Slab Phase Shifters on a Coplanar Waveguide

A simple steerable array antenna is designed and developed using a movable dielectric phase shifter. The change of effective dielectric constant at different dielectric slab positions on a coplanar waveguide is used as the phase shifter. The impedance matching and desired phase shift conditions are satisfied at two slab heights, and the reflection is designed to be minimized at these slab positions. The low-loss dielectric material is used as the dielectric slab and is placed close to a coplanar transmission line with airgap. The 4times4 steerable array antenna with the phase shifters is designed and fabricated at 20 GHz. The H-plane radiation patterns are measured at different phase shift positions and compared with the expected results     

Influence of Si<Subscript>3</Subscript>N<Subscript>4</Subscript> passivation on surface trapping in SiC metal-semiconductor field-effect transistors

The SiC metal-semiconductor field-effect transistors (MESFETs) have been reported to have current instability and strong dispersion caused by trapping phenomena at the surface and in the substrate, which degrade direct-current (DC) and radio-frequency (RF) performance. This paper illustrates the change in electrical characteristics of SiC MESFETs after Si₃N₄ passivation. Because of a reduction of surface trapping effects, Si₃N₄ passivation can diminish current collapse under pulsed DC conditions, increasing the RF power performance. The reduction of surface trapping effects is verified by the change in the ratio of the drain current to the gate current under pinch-off conditions.     

武装直升机对地攻击阶段作战效能评估

针对武装直升机对地攻击阶段的作战效能评估问题,采用概率分析方法将武装直升机作战过程分解并抽象为一组概率值,建立了相应的任务效率评估模型,并结合层次分析获得攻击方式效能评估模型.通过这两种模型获得的效能值可以为指挥人员合理科学地组织利用武装直升机和武器资源,以及确定当前作战环境下的最佳攻击方式提供参考.并通过具体的算例,编程仿真验证了该方法的有效性.     

Data Randomization Scheme for Endurance Enhancement and Interference Mitigation of Multilevel Flash Memory Devices

In this letter, we propose a data randomization scheme for endurance and interference mitigation of deeply‐scaled multilevel flash memory. We address the relationships between data patterns and the raw bit error rate. An on‐chip pseudorandom generator composed of an address‐based seed location decoder is developed and evaluated with respect to uniformity. Experiments performed with 2x‐nm and 4x‐nm NAND flash memory devices illustrate the effectiveness of our scheme. The results show that the error rate is reduced up to 86% compared to that of a conventional cycling scheme. Accordingly, the endurance phenomenon can be mitigated through analysis of interference that causes tech shrinkage.     

Performance of Efficient Signal Detection for LED-ID Systems

In this paper, effects of reader-to-reader interference are investigated for LED identification (LED-ID) system in a multi-reader environment. The LED-ID readers typically use different channels to avoid collision between readers. However, in-channel collision usually happens in terms of interrogation range. A reader-to-reader interference scenario is proposed, and nominal interrogation range of a desired reader is derived from this model. In order to evaluate the LED-ID reader-to-reader interference quantitatively, an efficient detection scheme is proposed and simulated by employing spreading sequence. The spreading sequence is inserted between each user’s frame formats. In the receiver, the desired signal is detected by using correlation among inserted spreading sequences. From simulation results, it is confirmed that the proposed scheme is very effective to enhance reliability of LED-ID communication systems.     

Bendable and Splitter-Integrated Optical Subassembly Based on a Flexible Optical Board

A bendable and splitter-integrated optical subassembly (OSA) is suggested as a short-distance board-to-board optical interconnection. This OSA was fabricated by simply packaging a vertical-cavity surface-emitting laser on a flexible optical board having an embedded 1 $times$ 8 optical splitter waveguide. Finally, we measured various optical characteristics of the OSA, including insertion, twist, and bending losses.      

A single-input dual-output 13.56 MHz CMOS AC–DC converter with comparator-driven rectifiers for implantable devices

A highly efficient single-input, dual-output AC–DC converter for wireless power transfer in implantable devices is implemented using the 0.18-µm CMOS process. The proposed AC–DC converter, consisting of three rectifiers with cross-coupled NMOS transistors and comparator-driven PMOS transistors, achieves up to 79.5% power conversion efficiency at 13.56 MHz operation frequency in order to provide dual outputs of 1.2 V and 2.2 V DC voltages along with 6.2 mA and 22.6 mA of current, respectively, to the implant device from a single RF input. The designed IC consumes a core die area of 0.18 mm².     

不同调节剂对烟草根系发育与生理特性影响的研究

采用盆栽和池栽试验,研究了ABT₄、黄腐酸盐和FeSO₄对烟草根系发育动态及其生理特性的影响。结果表明:烟草根系活力的变化动态呈双峰曲线,根系活力高峰分别出现在移栽后30d和80d;根系的钾素吸收与烟碱合成动态与根系活力趋势相同,但其峰值期略有差异。ABT₄和黄腐酸盐对根系活力、根量、钾素吸收和烟碱合成均有促进作用,并且,ABT₄的作用主要表现在前期,黄腐酸盐的后劲较长;FeSO₄对根长、根量的促进作用较弱,对根系活力、钾素吸收和烟碱合成的作用主要表现在后期。