基于STC12C2052的人民币识别控制系统的设计

设计研究人民币纸币识别控制系统中的主要模块,如图像采集、控制模块。在硬件部分,选用STC12C2052作为控制系统的芯片,选用MVC1000M作为图像的采集器件;在软件部分,在红外和紫外光源的作用下通过高清摄像头拾取图影信息,通过与数据库中的真版人民币特征的数据比对来判断真伪,选取预处理之后的纸币图像的尺寸特征用模糊逻辑推理方法识别图像的面值,提取矩作为特征。通过实验证明该控制系统的有效性和可行性。     

汽车自动巡航系统PID控制策略的研究

文章介绍汽车自动巡航控制系统的结构组成和工作原理,选择基于Atmega 8单片机的PID控制策略实现车辆的稳定行驶及加速、减速的控制过程.本系统能有效地减轻长途驾驶中驾驶员的工作强度,提高舒适性,并减少燃料消耗,利于环保.     

安全协议DoS攻击的形式化分析方法研究

针对形式化方法对安全协议DoS攻击分析的不足之处,提出了一种基于串空间模型的扩展形式化方法。利用扩展后的形式化方法,对IEEE802．11i四步握手协议进行了DoS攻击分析,发现其的确存在DoS攻击漏洞。通过分析,提出一种可以改善DoS攻击的方法,并通过了扩展形式化方法对于判断安全协议DoS攻击分析的测试规则。最后,根据扩展形式化方法对改进后的四步握手协议进行证明,得出改进后协议可以通过两类DoS测试规则运行至结束。     

LC-VCO design optimization at 1/f 2 phase noise performance in 65 nm CMOS technology

A way of analytical calculation in the phase noise modeling of the LC-VCO topology without tail current resource is proposed. The noise current imported by the MOS channel is modeled to give approximate evaluation, and the period of the transistor noise is included in the model. Phase noise introduced by the tank loss resistance is also modeled to evaluate the circuit phase noise performance. The circuit has been implemented in a 65 nm CMOS technology. The chip occupies 951 × 705 um² areas with the buffer and pads. The test result indicates that the VCO core consumes 1.125 mW with a 1.2 V power supply, the frequency of the VCO baseband is from 1.258 to 1.37 GHz, and the multiband frequency is from 0.86 to 1.37 GHz. The best performance of the LC-VCO shows a phase noise of ?129.57 dBc/Hz at 1 MHz offset frequency from a 1.3 GHz carrier, resulting in an excellent FoM of ?191.27 dBc/Hz.     

激光熔覆WCp/Ni-Cr-B-Si-C自熔合金复合涂层的显微结构及干滑动磨损

运用激光熔覆技术在４５＃钢表面制备了ＷＣｐ增强Ｎｉ－Ｃｒ－Ｂ－Ｓｉ－Ｃ复合涂层。含量为３０ｖｏｌ－％ＷＣ典型涂层的ＸＲＤ,ＳＥＭ和ＴＥＭ分析表明,ＷＣｐ在熔覆的熔化阶段发生部分溶解和分解。激光熔体凝固时形成的微观组织由Ｎｉ＋Ｎｉ３Ｂ共晶基体上分布的杆（或薄片）状α－Ｗ２Ｃ,块状β－Ｗ２Ｃ和四方形η１碳化物Ｍ６Ｃ相组成。这类碳化物主要含Ｗ,并含大量Ｃｒ。销－环式干滑动磨损试验表明,当ＷＣｐ含量约为３０ｖｏｌ－％时,磨损抗力最大     

稀土离子电子振动光谱高灵敏检测技术--稀溶液中氨基酸与稀土的配位研究

叙述了稀土离子电子振动光谱的时间分辨高灵敏检测技术,并利用该技术研究了铽离子与精氨酸在稀溶液中的配位,定量地确定了水配位随溶液ｐＨ值的改变而发生的变化。结果表明,当ｐＨ＞１时,精氨酸可以参与铽离子配位,随着ｐＨ值的增加配位逐渐加强。     

An Effective Differential Fault Analysis on the Serpent Cryptosystem in the Internet of Things

Due to the strong attacking ability, fast speed, simple implementation and other characteristics, differential fault analysis has become an important method to evaluate the security of cryptosystem in the Internet of Things. As one of the AES finalists, the Serpent is a 128-bit Substitution-Permutation Network （SPN） cryptosystem. It has 32 rounds with the variable key length between 0 and 256 bits, which is flexible to provide security in the Internet of Things. On the basis of the byte-oriented model and the differential analysis, we propose an effective differential fault attack on the Serpent cryptosystem. Mathematical analysis and simulating experiment show that the attack could recover its secret key by introducing 48 faulty ciphertexts. The result in this study describes that the Serpent is vulnerable to differential fault analysis in detail. It will be beneficial to the analysis of the same type of other iterated cryptosystems.     

基于电磁场原理的航天器变频吸振技术

为了有效抑制航天器转动部件对敏感载荷的扰动,将电磁技术应用于变频吸振器上,从经典电磁理论出发,建立了斥力悬浮型电磁变频装置的数学模型。该型电磁变频装置通过两个电磁铁对中间的永磁体产生排斥作用来产生恢复力:当中间永磁体偏离平衡位置时,由于两边电磁铁斥力的非线性变化使得二者对中间永磁体产生一个指向平衡位置的恢复力。理论分析表明,在气隙不大的情况下,该力与永磁体偏离平衡位置的位移成正比,同时其与电磁铁中通入的电流成正比关系,进一步的仿真也验证了该结论,这为有效、精确控制变频吸振器的工作频率提供了理论依据。根据理论计算和有限元仿真,采用了电磁技术的变频装置可以提供4 500 N/m左右的刚度变化范围,应用该变频装置的吸振器可以提供近50 Hz的频率变化范围,同时其调节速度和精度也能满足航天器对变频吸振器相关性能的要求。     

A General Ammonium Salt Assisted Synthesis Strategy for Cr3+-Doped Hexafluorides with Highly Efficient Near Infrared Emissions

The discovery of highly efficient broadband near infrared (NIR) emission material is urgent and crucial for constructing NIR lighting sources and emerging applications. Herein, a series of NIR emission hexafluorides A₂BMF₆:Cr³⁺ (A = Na, K, Rb, Cs; B = Li, Na, K, Cs; M = Al, Ga, Sc, In) peaking at ≈733–801 nm with a full width at half maximum (FWHM) of ≈98–115 nm are synthesized by a general ammonium salt assisted synthesis strategy. Benefiting from the pre-ammoniation of the trivalent metal sources, the Cr³⁺ can be more efficiently doped into the A₂BMF₆ and simultaneously prevent the generation of the competitive phase. Particularly, Na₃ScF₆:Cr³⁺ (λ_em = 774 nm, FWHM ≈ 108 nm) with optimal Cr³⁺-doping concentration of 35.96% shows a high internal quantum efficiency of 91.5% and an external quantum efficiency of ≈40.82%. A lighting emitting diode (LED) device with a NIR output power of ≈291.05 mW at 100 mA driven current and high photoelectric conversion efficiency of 20.94% is fabricated. The general synthesis strategy opens up new avenues for the exploration of Cr³⁺-doped high efficiency phosphors, and the as-obtained record NIR output power demonstrates for NIR LED lighting sources applications.     

High-Performance Solution-Processed Nondoped Circularly Polarized OLEDs with Chiral Triptycene Scaffold-Based TADF Emitters Realizing Over 20% External Quantum Efficiency

Recently, circularly polarized organic light-emitting diodes (CP-OLEDs) fabricated with thermally activated delayed fluorescence (TADF) emitters are developed rapidly. However, most devices are fabricated by vacuum deposition technology, and developing efficient solution-processed CP-OLEDs, especially nondoped devices, is still a challenge. Herein, a pair of triptycene-based enantiomers, (S,S)-/(R,R)-TpAc-TRZ, are synthesized. The novel chiral triptycene scaffold of enantiomers avoids their intermolecular π–π stacking, which is conducive to their aggregation-induced emission characteristics and high photoluminescence quantum yield of 85% in the solid state. Moreover, the triptycene-based enantiomers exhibit efficient TADF activities with a small singlet-triplet energy gap (ΔE_ST) of 0.03 eV and delayed fluorescence lifetime of 1.1 µs, as well as intense circularly polarized luminescence with dissymmetry factors (|g_PL|) of about 1.9 × 10⁻³. The solution-processed nondoped CP-OLEDs based on (S,S)-/(R,R)-TpAc-TRZ not only display obvious circularly polarized electroluminescence signals with g_EL values of +1.5 × 10⁻³ and −2.0 × 10⁻³, respectively, but also achieve high efficiencies with external quantum, current, and power efficiency up to 25.5%, 88.6 cd A⁻¹, and 95.9 lm W⁻¹, respectively.