An Efficient(k,p) Notational System Transform Algorithm

多进制编码和混合进制编码广泛应用于信息隐藏领域,影响其编码性能的一个关键因素是进制转换效率.针对任意k进制序列到P进制序列的相互转换,提出一种高效的进制转换算法,并根据信息论证明了其最优性.利用新算法改进了kT-lEX文本隐写系统、网页等价标记隐写术、图着色编码和APPM编码等多种基于混合进制编码和分组多进制编码的隐写术,有效提高了原方法的隐写性能.理论分析和实验结果均表明了该算法的有效性.Muti-ary codes and mix-ary codes are widely used in information hiding, while the transfer efficiency between notational systems is an important factor of coding efficiency.An effective notational system transfer algorithm based on double-coding method is proposed for transforming arbitrary k-ary sequences to p-ary sequences.It is proved that the proposed notational system transform algorithm is optimal.The method is applied to improve embedding efficiency of several kinds of steganographic algorithms based on mix-ary codes or grouped multi-ary codes, including KT-Lex steganographic system, webpage steganography based on equal tag, grid coloring codes and APPM codes.Both theory analysis and experimental results show that the proposed method is effective.国家自然科学基金(No.60803155;No.60970141;No.60902102;No.61274133); 中国科学院战略性先导专项课题基金(No.XDA06030601); 国家重大科技专项基金(No.2010ZX03004-003); 郑州市科技创新团队项目基金(No.10CXTD150)资

掺稀土半导体光电特性和应用

结合我们近年来在掺稀土硅基材料和Ⅲ-Ⅴ族化合物半导体材料的发光研究，简述目前国际上在这方面研究的新进展，重点介绍掺铒硅基发光和掺稀土GaN发光材料和器件的研究结果

掺铒GaN薄膜光致发光的研究

采用傅立叶变换红外光谱（FT－IR）研究了掺铒GaN薄膜光致发光特性，光致发光谱（PL）的测量结果表

A Design of Low Voltage,Low Distortion Class AB Power Amplifier for Audio Application

就解决现有音频功率放大器中噪声高、失调大的问题,设计制作了一种0.6μm线宽的低压、低失真AB类音频功率放大器.器件采用BTL结构的差动输出,以简单的结构达到高质量音频重现.在设计中,采用前馈式AB类控制方式解决静态电流的控制,并增加浮动AB类控制减小失配,改善了传统AB类放大在噪声、失调等方面的性能.实验测试结果表明,供电电压为5 V时在关断模式下,将静态电流消耗减小到0.2μA以下;电源抑制比高于80 dB;总谐波失真在1%内.In order to improve traditional audio power amplifier's the noise and offset performance,we design a low-cost,stereo audio power amplifier.The audio power amplifiers are ideal for portable audio devices with internal speakers.Abridge-tied load(BTL) architecture minimizes external component count,while providing high-quality audio reproduction.We used feedforward Class AB control to solve the quiescent current control,improving the noise and offset performance.The test results in low-power shutdown mode,reducing quiescent current consumption to less than 0.2 μA;power supply rejection rate(PSRR) could reach 80 dB and the total harmonic distortion(THD) is less than 1% while operating from a single +5 V supply.福建省自然科学基金(2002H020)资

Development of CMOS Digital Integration Temperature Sensor

为了准确监测65 nm工艺的高速CPU芯片的工作温度,以保证CPU工作时风扇的运转以及过热报警,本文介绍了0.6μm的CMOS工艺设计实现的一种集成I2C总线通讯的具有远程测温功能的智能温度传感芯片.详细介绍了串联晶体管结构和Δ-ΣA/D转换技术、非重叠的控制时钟和CMOS开关的消除电荷注入误差的设计,使温度精度达到0.2℃;输出数字信号与I2C总线通讯的接口设计简化了后续信号处理和接口电路设计.测试结果表明,检测的温度范围从-15℃到95℃,本地温度误差在1℃以内,远程温度误差在0.75℃以内.In order to accurately monitor the temperature of 65 nm process microprocessors and turn on the system fans or shutdown the system,a digital integration temperature sensor used 0.6 μm standard complementary metal-oxide semiconductor(CMOS) technology with I2C management bus interface is presented in this paper,which can monitor the temperature of a remote diode.We used two series-wound bipolar,Δ-Σ A/D converter,and non-overlapping clock as well as CMOS switches to eliminate charge injection error,which make the temperature accuracy 0.2℃.Digital signal output communicated with I2C management bus,simplifies the signal processing and interface circuit.The test result shows that the circuit can provide a resolution of 1℃ at local channel and 0.75℃ at remote channel from-15℃ to 105℃.福建省自然科学基金(2002H020)资

掺铒nc-Si/SiO_2薄膜中nc-Si和Er~(3+)与非辐射复合缺陷间相互作用对薄膜发光特性的影响

对nc-Si/SiO_2薄膜中纳米硅(nc-Si)、Er~(3+)和非辐射复合缺陷三者间的关系作了研究.在514.5 nm光激发下,nc-Si/SiO_2薄膜在750nm和1.54μm处存在较强的发光,前者与薄膜中的nc-Si有关,后者对应于Er~(3+)从第一激发态4I13/2到基态4I15/2的辐射跃迁.随薄膜中Er3+含量的提高,1.54μm处的发光强度明显增强,750 nm处的发光强度却降低.H处理可以明显增强薄膜的发光强度,但是对不同退火温度样品,处理效果却有所不同.根据以上实验结果,可得如下结论:在nc-Si颗粒附近的Er~(3+)和其他的缺陷组成了nc-Si颗粒内产生的束缚激子的非辐射复合中心,束缚激子通过Er~(3+)的非辐射复合,激发Er~(3+)产生1.54μm处的发光,同时降低了750nm处的发光强度.nc-Si颗粒附近其他非辐射复合中心的存在会降低Er~(3+)被激发的概率,引起1.54μm处的发光强度降低

Simulation Research Output Efficiency of Hexagonal LED Chip

近年来,人们对lEd的出光效率和出光的效果进行了大量的研究和改进。有研究机构做出了六边形的lEd芯片,实践中在光学性能、出光效率和成本上比传统的lEd芯片有较大的优势。因此利用TrACEPrO仿真软件对不同形状的lEd芯片进行模拟,并通过对比验证仿真结果的正确性和仿真方法的可行性。仿真结果表明,六边形芯片的lEd模型在光线扭曲和暗点的问题上比传统芯片的lEd模型得到了明显的改善,照度均匀性得到明显的增强,光能的输出效率上也有一定的提高。对比两种芯片的lEd模型在当下比较常见的封装模式下的光学性能,结果表明六边形芯片的lEd模型在光强或均匀度上都要好于正方形芯片的lEd模型。Many researches have been done to improve the output efficiency and lighting effects of the LED in recent years.Some research institutions have made hexagonal LED chip with great advantages at optical properties,output efficiency and cost compared with conventional LED chip.Therefore,the TracePro simulation software was utilized to simulate the different shapes of the LED chips in this work.The correctness and feasibility were verified by comparing the simulation results.The simulation results showed that the hexagonal LED chip model did conduced to distorted light and dark spots improving,illumination uniformity enhancing and output efficiency increasing of optical energy compared with the traditional chip LED model.By Contrasting the optical properties of the LED model in the common package mode of the two chips,the hexagonal chip LED model preformed better in both the light intensity and uniformity.国家“973”计划项目(2012CB619301); 国家“863”计划项目(2011AA03A111); 中央高校基本科研业务费专项资金资助项目(2012121014、CXB2011029

Cognitive Aging and Executive Decline Hypothesis

在认知年老化领域,执行衰退假说是近年来新兴的一种理论。执行衰退假说在理论上具有很强的吸引力,但在实证研究中却存在很多困难,如执行功能的可分离性问题,执行功能测量的信度和效度问题,以及执行功能与加工速度的关系问题。目前,该领域研究的焦点是:在行为学水平上,控制一般性因素(加工速度)后,执行功能是否仍对认知年老化起重要的中介作用; 在神经水平上,执行(额叶)功能随龄的变化情况,以及在认知年老化过程中,额叶在大脑功能重组中扮演的角色。最终实现对认知年老化的理解,需要将认知功能与大脑结构联系起来; 既看到广泛存在的共同的基本机制,又不能忽略不同认知结构的选择性变化

认知年老化与执行衰退假说

在认知年老化领域,执行衰退假说是近年来新兴的一种理论。执行衰退假说在理论上具有很强的吸引力,但在实证研究中却存在很多困难,如执行功能的可分离性问题,执行功能测量的信度和效度问题,以及执行功能与加工速度的关系问题。目前,该领域研究的焦点是:在行为学水平上,控制一般性因素(加工速度)后,执行功能是否仍对认知年老化起重要的中介作用; 在神经水平上,执行(额叶)功能随龄的变化情况,以及在认知年老化过程中,额叶在大脑功能重组中扮演的角色。最终实现对认知年老化的理解,需要将认知功能与大脑结构联系起来; 既看到广泛存在的共同的基本机制,又不能忽略不同认知结构的选择性变化