一种新的双重门限证实数字签名方案

在已有的(t,n)门限数字签名方案及证实数字签名的基础上,提出了新的双重门限证实数字签名方案(t1,n1;t2,n2)。新方案首次在签名证实阶段引入了门限方案,由一群符合一定条件的t2个人组成证实者(confirm er)。因为是由不同的各方参与进来,方案具有了更加广泛的可信任性,从而使得该方案适用于某些安全程度要求较高的情况。     

基于双线性函数的门限签名方案

门限签名是现代电子商务一种重要的数字签名。利用基于椭圆曲线上的双线性对函数,减少了计算量;利用Shamir秘密共享技术共享一个用户的私钥,而不是共享密钥生成中心的主密钥,提高方案的安全性。利用Gennaro可模拟的思想,证明了提出的方案具有健壮性和不可伪造性,因此是安全的。与传统的方案相比,新方案具有更高的计算效率。     

一种新的有效的群签名方案

介绍了一种有效的群签名方案。该方案的安全性是基于译码问题的难度和线性码的纠删特性和ElGamal签名方案的安全性。已知[n,k,d]码和相应的数字签名方案,则签名和群公钥的长度分别是n+5和n2+5。对于方案的计算代价,签名过程除O(n)算术运算外基本上与ElGamal方案相同;打开签名的过程非常有效,只需O(d2)运算量。方案允许新成员加入群时不修改群公钥。通过向某些成员分发新的成员资格证书,可以将成员从群中删除。     

一个证实门限数字签名方案的安全漏洞分析

证实数字签名协议是一种需要签名者、证实者和验证者三方参与的特殊的数字签名方案,除了签名者,其他任何人都不能以签名者的名义产生有效的证实签名;同样除了证实者,其他任何人也不能对签名的有效性作出判断。文献[8]是一个新的证实门限数字签名协议,是秘密共享思想与证实数字签名方案的新结合,但提出的新方案并未满足证实数字签名协议的某些要求,因此存在着安全漏洞;本文对此进行了详尽的分析,指出了其设计不足之处,从而说明新协议并没有实现其预期设计目标。     

PCM/PPK再入遥测系统性能分析

PCM/PPK再入遥测系统是一种多进制脉冲位置调制系统,具有抵抗码间干扰能力强、能量效率高的特性。在该系统中,码元之间不是相互独立的,基于PCM码的群码特性,分析了在择大检测下PCM/PPK系统的误码性能和误差特性,并与固定门限判决下的误码性能和误差特性进行了比较,结果表明,在小信噪比时择大检测劣于固定门限检测,而在大信噪比时优于固定门限检测。     

一个改进的带消息恢复的代理盲签名方案

在普通的代理签名中,原始待签消息可能含有原始签名者或消息接收者的机密信息,但不希望代理签名者看到待签消息的明文。针对这一问题引入了盲签名体制。文章基于Schnorr算法,结合代理签名和盲签名提出了一个新的代理盲签名方案,使得只有原始签名者和消息接收者能看到原始待签消息,代理签名者看不到消息明文。另外在方案中引人了时间戳和生存期,有效解决了原始签名者和代理签名者相互抵赖的问题。     

基于Schnorr算法的不可否认签名方案

根据Schnorr算法及不可否认数字签名方案的特点,提出了一个适合软件签名的不可否认签名方案,其安全性依赖于有限域上的计算离散对数问题的困难性。     

面向办公自动化的群签名解决方案

随着办公自动化(OA)近年的飞速发展,对于数字签名的要求越来越高,这不仅体现在数字签名的安全程度上,同时也对签名形式的多样性提出了要求。群签名是近年来提出的一种新型签名方案,由于OA系统本身所特有的易于管理,效率高等特点使的该项技术较之在电子商务领域有着更高的可行性,本文论述了利用群签名算法结合证书认证等技术,创建一个针对办公自动化的群签名应用方案。     

基于先验门限优化准则的探测阈值自适应选择

针对 2维测量和 4 -sigma确认门 ,把先验检测门限优化准则和修正 Riccati方程的解析近似表示相结合 ,得到了在瑞利起伏环境下使跟踪性能优化的信号探测阈值解析表示式 ,从而使在线求解自适应信号探测阈值能比较容易地实现。通过研究和仿真发现 :在滤波稳定阶段 ,本文给出的自适应信号检测门限方法的跟踪性能优于固定虚警率方法的跟踪性能 ;基于先验检测门限优化准则实现检测 -跟踪的联合优化要求信噪比要大于一定的门限 ,在瑞利起伏环境下 ,对 2维测量和 4 -sigma确认门 ,该门限为 1 .57     

基于模糊逻辑推理的船舶并联气电混合动力系统能量最优分配研究

针对内河船舶工况启停变化频繁导致瞬态动力性较差、动态响应较慢等问题，提出并联气电混合动力系统改进方案，利用模糊逻辑推理方法来提升动力响应性能。以某内河拖船为研究对象进行混合动力系统参数匹配设计，通过对系统关键参数设计切换规则，建立基于逻辑门限的能量管理控制策略；为进一步优化逻辑门限方法主观设定边界阈值不可调节问题，提出基于“模糊逻辑推理+动态协调”能量最优分配策略。通过最优设计相关试验验证管理策略，结果表明：采用基于模糊逻辑推理的能量管理策略能使天然气发动机的平均负荷提升37.86%，平均效率提高2.74%，动态响应时间缩短44.45%。     

New criterion for aircraft susceptibility to infrared guided missiles

This paper assesses aircraft susceptibility from the first principles, with respect to the threat posed by passively guided infrared homing missiles; with an objective of gaining insight into the comprehensiveness of the relationship between aircraft susceptibility and aircraft infrared signature level. The conventional criterion of aircraft susceptibility assessment based on its lock-on envelop is found to be inadequate, and a new criterion termed here as the Lethal Envelop is presented. The proposed susceptibility assessment criterion is more relevant for coming generation of infrared-guided missiles, because of advancements in the infrared detection technology. A threshold infrared signature level is also proposed as benchmark to be satisfied by all infrared signature suppression systems; if aircraft susceptibility to infrared guided missiles is to be reduced. This analysis is vital for gauging the effectiveness of infrared signature suppression systems. A typical air-to-air combat situation is simulated, and the results that lead to aircraft susceptibility assessment are obtained from this model, which illustrates the comprehensiveness of the redefined aircraft susceptibility assessment approach.     

Moving target detection via airborne HRR phased array radar

We study moving target detection in the presence of temporally and spatially correlated ground clutter for airborne high range resolution (HRR) phased array radar. We divide the HRR range profiles into large range segments to avoid the range migration problems that occur in the HRR radar data. Since each range segment contains a sequence of HRR range bins, no information is lost due to the division and hence no loss of resolution occurs. We show how to use a vector autoregressive (VAR) filtering technique to suppress the ground clutter. Then a moving target detector based on a generalized likelihood ratio test (GLRT) detection strategy is derived. The detection threshold is determined according to the desired false alarm rate, which is made possible via an asymptotic statistical analysis. After the target Doppler frequency and spatial signature vectors are estimated from the VAR-filtered data as if a target were present, a simple detection variable is computed and compared with the detection threshold to render a decision on the presence of a target. Numerical results are provided to demonstrate the performance of the proposed moving target detection algorithm     

基于小波包分解和滑动功率谱的舰船轴频电场信号检测

轴频电场是可在水下探测到的一种运动舰船特征物理场,由于海水的衰减作用,其信号十分微弱。文章提出了一种基于小波包分解和滑动功率谱的微弱舰船轴频电场信号检测方法。首先,利用小波包变换对观测信号进行多子带分解;然后,分别提取各子带信号功率作为检测特征量,使用浮动门限对其进行滑动检测。实测数据和仿真数据处理表明,该方法能够在较低的信噪比条件下有效工作,性能优于传统的功率谱检测方法。     

直升机排气系统用波瓣喷管引射-混合式红外抑制器研究

 在针对直升机排气系统用波瓣喷管引射-混合式红外抑制器开展的一系列数值计算和模型实验研究基础上，本文对其内流气动特性和红外辐射特性进行较为系统的综合总结。揭示并分析了这种形式的红外抑制器内部混合流动特征，引射混合和隔热遮挡的红外抑制作用效果，以及红外抑制器缩比模型红外辐射模化关系；同时也指出了需进一步研究的一些问题。     

数字签名在校园网中的应用

本文介绍了数字签名技术的概念 ,数字签名技术的使用意义 ,及用JAVA实现数字签名的思想     

Inverse design of low boom configurations using proper orthogonal decomposition and augmented Burgers equation

Mitigation of sonic boom to an acceptable stage is a key point for the next generation of supersonic transports. Meanwhile, designing a supersonic aircraft with an ideal ground signature is always the focus of research on sonic boom reduction. This paper presents an inverse design approach to optimize the near-field signature of an aircraft, making it close to the shaped ideal ground signature after the propagation in the atmosphere. Using the Proper Orthogonal Decomposition(POD) method, a guessed input of augmented Burgers equation is inversely achieved. By multiple POD iterations, the guessed ground signatures successively approach the target ground signature until the convergence criteria is reached. Finally, the corresponding equivalent area distribution is calculated from the optimal near-field signature through the classical Whitham F-function theory. To validate this method, an optimization example of Lockheed Martin 1021 is demonstrated. The modified configuration has a fully shaped ground signature and achieves a drop of perceived loudness by 7.94 PLdB. This improvement is achieved via shaping the original near-field signature into wiggles and damping it by atmospheric attenuation. At last, a nonphysical ground signature is set as the target to test the robustness of this inverse design method and shows that this method is robust enough for various inputs.