利用震荡环频率特性提取多位可靠信息熵的物理不可克隆函数研究

针对传统物理不可克隆函数(PUF)产生信息熵少、易受环境因素干扰等问题,该文设计一种产生多位稳定信息熵的PUF方案。该方案通过对FPGA上环形震荡器所产生频率数据的分析,从每个震荡环中提取能够代表震荡环特性的特征位作为信息熵。通过对逆变器温度特性的研究,利用电流饥饿逆变器和常规逆变器组成新的震荡环来降低温度对产生的信息熵的可靠性的影响。通过Cadence IC仿真和进行赛灵思zynq 7000系列FPGA开发平台上的实验,结果表明改进的PUF结构使用相同数量的震荡环产生更多的信息熵,并且其可靠性、唯一性均得到提升。

     

Development and implementation of an FPGA based fractional order controller for a DC motor

Fractional calculus has been gaining more and more popularity in control engineering in numerous fields, including mechatronic applications. One of the most common applications in all mechatronic domains is the control of DC motors. Several control algorithms have been proposed for such motors, ranging from traditional PID algorithms, to the more sophisticated advanced methods, including fractional order controllers. Nevertheless, very little information regarding the implementation problems of such fractional algorithms exists today. The paper proposes a simple approach for designing a fractional order PI controller for controlling the speed of a DC motor. The resulting controller is implemented on an FPGA target and its performance is compared to other possible benchmarks. The experimental results show the efficiency of the designed fractional order PI controller. Beside the initial DC motor, two other different DC motors are also used in the experiments to demonstrate the robustness of the controller.     

Effects of size, humidity, and aging on particle removal from Si wafers

The effects of particle size, humidity, and aging time on particle removal from silicon wafers were investigated with a laser shock wave at a constant removal force. Particle adhesion force, shock wave cleaning force, and the removal moment ratio were calculated and related to particle removal efficiency (PRE). The presence of capillary forces and particle deformation significantly increased the adhesion force. In order to control the humidity and magnitude of deformation, humidity and aging time were varied during particle removal tests. PRE decreased rapidly for particle sizes below 1 μm as the humidity and contact area increase. The calculations of removal moment ratios agreed well with the experimental observations. Both humidity and process time should be controlled to avoid the aging of particles and to achieve high PRE for particles smaller than 1 μm.     

白光LED老化机理研究进展

介绍了国内外在老化机理研究方面采用的加速老化方法,主要从深能级和非辐射复合中心的增加、接触电极金属的电迁移和退化、散热不良导致的电极缓慢或灾变性失效、封装材料的老化、荧光粉的劣变、静电的影响等方面来分析老化机理.同时介绍了根据这些研究而采取的各种改善措施.     

Effects of group V precursor and step structure on ordering in GaInP

The effects of the P precursor have been studied for GaInP layers grown at 670°C on singular (001) GaAs substrates. Use of either of the two precursors, tertiarybutylphosphine (TBP) and phosphine (PH₃), for the organometallic vapor phase epitaxial growth, has been shown to result in the same degree of CuPt order in the epitaxial layers. However, the steps on the surface are mainly bilayers, approximately 5.8Å in height, for growth using TBP and mainly monolayers for growth using PH₃. This indicates that the step structure plays no role in the ordering process occurring on the surface during growth. Examination of the spacing between these surface steps vs the input partial pressure of the P precursor indicates that neither the surface diffusion coefficient nor the sticking coefficients of group III adatoms at the step edge is dependent on the P precursor. This suggests that the step structure also has no effect on the sticking coefficient.     

MB-OFDM-UWB定位系统中交织器与解交织器设计

考虑到超宽带无线通信系统在高精度定位中需要极低的误码率,而实际通信中比特差错经常成串发生,为此在MB?OFDM?UWB通信中采用一种交织技术将连续误码分散成非连续误码,这样信道的突发错误在时间上得以扩散,使得此类误码大为降低,在接收端利用解交织器完成反交织。以上方案利用FPGA编程实现,并下载到目标板中,使用ChipScope在线测试和验证设计的正确性。     

Elevated temperature aging of solder joints based on Sn-Ag-Cu: Effects on joint microstructure and shear strength

The shear strength behavior and microstructural effects after aging for 100 h and 1,000 h at 150°C are reported for near-eutectic Sn-Ag-Cu (SAC) solder joints (joining to Cu) made from Sn-3.5Ag (wt.%) and a set of SAC alloys (including Co- and Fe-modified SAC alloys). All joints in the as-soldered and 100-h aged condition experienced shear failure in a ductile manner by either uniform shear of the solder matrix (in the strongest solders) or by a more localized shear of the solder matrix adjacent to the Cu₆Sn₅ interfacial layer, consistent with other observations. After 1,000 h of aging, a level of embrittlement of the Cu₃Sn/Cu interface can be detected in some solder joints made with all of the SAC alloys and with Sn-3.5Ag, which can lead to partial debonding during shear testing. However, only ductile failure was observed in all solder joints made from the Co- and Fe-modified SAC alloys after aging for 1,000 h. Thus, the strategy of modifying a strong (high Cu content) SAC solder alloy with a substitutional alloy addition for Cu seems to be effective for producing a solder joint that retains both strength and ductility for extended isothermal aging at high temperatures.     

L-DACS1系统定时同步的FPGA设计与实现

针对航空信道的复杂性和对信号干扰较大的问题,利用L-DACS1反向链路随机接入帧结构的特点,研究了粗定时同步与精定时同步的算法,并基于现场可编程门阵列（FPGA）在Apex-CPCI-5610通信开发板上实现了这种算法,应用于实际的项目上.测试结果表明,该方法能够精确得到定时同步的位置且系统工作稳定,能够满足L-DACS1系统的设计要求.     

基于FPGA的EoS系统中帧处理的改进与实现

根据ITU-T X.86协议的规定,设计了一种EoS系统,实现了IP数据包在基于SDH的骨干光传输网络中的高速传输.针对现有帧处理方案在帧同步时延和时钟抖动方面存在的问题,提出了改进的快速帧同步机制和时钟提取方案.采用廉价的FPGA硬件编程实现,通过电路综合与时序仿真表明,方案在缩短帧同步时延和消除时钟抖动方面具有较好的效果.     

Effects of increased compressive strain on hole effective mass and scattering mechanisms in strained Ge channels

Effects of increased compressive strain on the hole effective mass in the strained Ge channel structures was systematically studied. The effective mass was found to increase very sensitively with the hole density, and hence accurate strain dependence was evaluated by means of extrapolation of experimentally obtained mass values to a certain hole density (2.0 × 10¹² cm^-2). As a result, it was demonstrated that the effective mass monotonically decreased from 0.195 down to 0.150 m₀ with the increase in the compressive strain from 0.8% up to 2.8%, indicating that introduction of the larger strain into the Ge channel can enhance the hole mobility further. We also studied effects of the increased strain on dominant scattering mechanisms through evaluation of Dingle ratios. It was found that with increasing strain in the Ge channel, the interface roughness scattering became more significant in addition to the impurity scattering. We revealed that the roughness at the top Ge/SiGe heterointerface brought by the increased strain is responsible for the scattering and that this roughness scattering can be effectively suppressed by inserting a modulation-doping layer underneath the channel layer.