基于高阶幂的单快拍LDACS系统波达方向估计

L波段数字航空通信系统(L band digital aeronautical communication system,LDACS)是未来航空宽带通信重要的基础设施之一,针对LDACS信号容易受到相邻波道大功率测距仪(distance measuring equipment,DME)信号干扰的问题,提出了联合正交投影干扰抑制与单快拍稀疏分解的波达方向(direction of arrival,DOA)估计方法。通过子空间投影抑制DME干扰,然后使用单快拍数据构建伪协方差矩阵,对伪协方差矩阵求高阶幂,之后进行奇异值分解,并利用约束条件求解稀疏解得到期望信号来向的估计值。所提方法使用高阶伪协方差矩阵降低了噪声影响,仅用单快拍就可以准确估计LDACS信号的入射方向。仿真结果表明,改进单快拍高级幂(improved single snapshot high order power,ISS-HOP)L1-SVD算法的估计精度优于ISS-HOP-MUSIC算法。该方法可以有效抑制DME干扰,提高OFDM接收机性能。

盐湖大气环境下316 L仪表管点蚀深度预测研究

为提高316 L仪表管在盐湖大气环境下点蚀深度的预测精度,采用变阶平均弱化缓冲算子、积分背景值和新陈代谢对分数阶累加灰色模型FGM(1,1,r)进行改进,首先通过改进Tent混沌映射、莱维飞行和区间自适应反向学习策略提高黏菌算法(SMA)的寻优能力和收敛速度,随后利用改进黏菌算法(ISMA)对FGM(1,1,r,ρ)中的参数r和ρ进行寻优,最后构建仪表管ISMA-FGM(1,1,r,ρ)点蚀深度预测模型。研究结果表明:经优化的新模型比原模型误差更小、拟合度更高,在仪表管点蚀深度预测方面具有更好的性能。研究结果可为仪表管道系统的完整性评价和风险预警提供参考。

基于RANS/LES混合方法的三维L型弯管流场特性数值模拟

L型弯管是船用典型部件,可实现流体质量输运和热量交换等功能。由于弯曲段曲率的影响,其内部流动十分复杂。传统的雷诺平均方法(RANS)无法模拟弯曲段的复杂流动,而大涡模拟方法(LES)则计算量太大。为此,采用RANS/LES混合方法对经典L型弯管进行数值模拟研究,该方法在近壁面区域采用RANS方法,在湍流核心区采用LES方法,不仅可保持模拟精度,而且网格需求量较低更适用于工程应用。针对商软中的2类RANS/LES方法——脱体涡方法(IDDES)及应力混合涡模拟(SBES)方法,比较分析其在L型弯管内部流场仿真方面的优劣,并同时考虑流向曲率修正的影响。结果表明:SBES方法对弯管内二次流(迪恩涡)的预测能力优于IDDES方法,且曲率修正模型可进一步改善SBES方法的仿真结果。

Adaptive synchronization of hyperchaotic Lü system with uncertainty

This paper presents a novel adaptive control scheme for synchronization of the latest hyperchaotic Lü system. Based on the Lyapunov stability theory, a feedback controller and a parameter update law are designed for the synchronization of hyperchaotic Lfi systems with uncertainty. Numerical simulations are given to demonstrate the validity of the synchronization technique.

Global Exponential Projective Synchronization and Lag Synchronization of Hyperchaotic Lü System

This paper investigates the projective synchronization and lag synchronization of a new hyperchaotic system[Physica A 364(2006)103].On the basis of Lyapunov stability theory,two novel nonlinear controllers are respectivelydesigned to guarantee the global exponential projective synchronization(including complete synchronization and anti-synchronization)and lag synchronization.Finally,numerical simulations are given to show the effectiveness of the mainresults.

L-赖氨酸预处理及杀菌工艺对南极磷虾罐头品质的影响

研究相同杀菌强度下杀菌温度和杀菌时间对经过L-赖氨酸(L-lysine,Lys)预处理的南极磷虾罐头品质的影响。采用Lys进行预处理南极磷虾肉,分别以水和保水剂三聚磷酸钠为对照,在相同的杀菌强度下,研究115℃杀菌60 min、117℃杀菌38 min、119℃杀菌24 min和121℃杀菌15 min 4种杀菌条件对南极磷虾罐头品质的影响。在115℃杀菌60min后,Lys处理组的南极磷虾肉的硬度和咀嚼度较低,脂质氧化程度最低;低场核磁共振和核磁共振成像分析表明,不易流动水峰面积最大且伪彩图的信号强度最高;微观结构的结果显示,经Lys处理的南极磷虾肉组织更加规则,孔洞分布均匀,微观结构更完整;感官评价结果表明,在此杀菌条件下Lys处理组的南极磷虾肉具有较好的风味和质地,且在可接受度方面的评分也最高。Lys可替代磷酸盐改善南极磷虾罐头品质,且115℃杀菌60min的杀菌工艺使南极磷虾罐头品质最好,在实际生产操作中有很好的应用性。

基于改进L-P法的块系岩体摆型波与准共振机理分析

块系岩体中摆型波具有非线性特征,导致难以解释其频谱特征及准共振现象机理。针对此问题,建立了考虑三次项的摆型波非线性振动模型,利用改进的L-P法与振型叠加法,求得多自由度强非线性振动的近似解析解,一定程度上解释了试验观测到块系岩体摆型波的非线性现象机理。结果表明,块体系统振动频率可表示为输入能量的高次多项式,随能量增大振动频率呈非单调变化;各谐振频率之间的比例与系统构造有关,近似满足√2的整数倍比例关系。通过建立摆型波的层次构造模型,得出准共振是摆型波在不同尺度块体之间跃迁的标志。

Impulsive Synchronization of Hyperchaotic LüSystems with Two Methods

In the paper, impulsive synchronization of two hyperchaotic Lü systems with different initial conditions is studied. The sufficient conditions on feedback strength and impulsive distances are established from two different angles to guarantee the synchronization. The relevant theoretical proofs are presented. Numerical simulations show the effectiveness of the methods.

IMPROVED L-P METHOD FOR SOLVING STRONGLY NONLINEAR PROBLEMS

Using the improved L-P method, the authors seek to salve a class of problems of square strongly nonlinear free oscillations and of strongly nonlinear nonoscillations. Their first-order approximate solutions which has high accuracy are obtained. The method of this paper is different from the known L-P methods.

低信噪比场景下Link-16系统的联合频偏估计算法

对于Link-16数据链终端平台在低信噪比(SNR)高动态场景下的多普勒频率偏移问题,该文设计一种新的数据结构,推导了该结构下的克拉默-拉奥下界(CRLB),并在此基础上提出一种联合频域变换与时域自相关运算的分步式频偏估计算法。其基本思想是,首先对接收信号做自相关处理,然后通过频域变换进行最大值索引,结合修正因子得到多普勒频移的粗估计值,再利用时域的改进L&R算法对接收信号进行细估计,根据两步估计算法得到最终的频偏估计值。算法应用蒙特卡罗实验仿真,仿真结果表明,与传统频偏估计算法相比,该算法的归一化均方误差更接近CRLB,在多普勒频偏为[–20 kHz,20 kHz]时,估计精度可达10^(–5)。在低信噪比环境下,所提算法能达到较为理想的估计效果,适用于Link-16数据链通信。

2-median location improvement problems under weighted l_1 norm and l_∞ norm on trees

This paper focuses on the 2-median location improvement problem on tree networks and the problem is to modify the weights of edges at the minimum cost such that the overall sum of the weighted distance of the vertices to the respective closest one of two prescribed vertices in the modified network is upper bounded by a given value.l1 norm and l∞norm are used to measure the total modification cost. These two problems have a strong practical application background and important theoretical research value. It is shown that such problems can be transformed into a series of sum-type and bottleneck-type continuous knapsack problems respectively.Based on the property of the optimal solution two O n2 algorithms for solving the two problems are proposed where n is the number of vertices on the tree.

Propagation methods for black locust (Robinia pseudoacacia L.) improvement in Hungary

Black locust (Robinia pseudoacacia L.) is one of the most important stand-forming tree species in Hungary and its importance is increasing in many countries. Black locust plants are commonly produced by two methods, by seed and by root cuttings. Tissue culture propagation can be considered as a relatively new method. Growing trees from seed is a relatively sim-ple method for reliably producing seedlings on a large scale under a variety of circumstances. Mechanization of the method is easy and the production cost is relatively low. Propagation from root cuttings and tissue culture are valuable for reproduction of superior individuals or varieties. By applying these methods, superior traits of the selected trees can be preserved in the clones. Recent experiments demonstrated that micropropagated trees could be successfully transplanted into soil, hardened and grown in the field.

Comparisons of Three Recurrent Selection Methods in the Improvement of Maize Populations

The maize population Csyn 4 was improved for three cycles with three recurrent selection methods MS1, MS1-HS, and MHSRRS in northern China. A total of 40 NC Ⅱ testcrosses were made by four testers with Csyn 4 and 10 improved populations, which were evaluated in four environments in the cropping season of 2005. Analysis of variance indicated a significant progress （P〈 0.05） in yield and other chief agronomic traits in the improved populations and testcrosses, demonstrating that the three recurrent selection methods were effective for increasing grain yield of testcrosses and improvement of general combining ability in maize population. The average grain yield increase of population Csyn 4 in MS1, MS1-HS, and MHSRRS recurrent selections was 266.7 kg ha^-1 （5.3%）, 288.0 kg ha^-1 （5.7%）, and 231.3 kg ha^-1 （4.6%） per cycle, while the grain yield of S 1 progeny of population for Csyn 4 was increased by 420.0 kg ha^-1 （10.9%）, 376.0 kg ha^-1 （9.8%）, and 414.7 kg ha^-1 （10.8%） per cycle in MS1, MS1-HS, and MHSRRS recurrent selections, respectively. Linear responses （b） in the MS1, MS1-HS, and MHSRRS recurrent selections were the same as the realized responses of the selection （G） for grain yield increase of Csyn 4 and S1 progeny of the populations. The grain yield of testcrosses increased by 3.3-5.2% on average per cycle. The value of heterosis did not display any differences amongst the different cycles of selections. The GCA for yield component traits of population Csyn 4 was improved significantly by means of three selection methods, whereas the GCA for plant height, ear height, days to silking, and days to pollen did not show significant increase in the recurrent selections. GCA for the number of tassel branches were decreased in the selections, while GCA for the number of plant leaves were increased, but the difference was not significant.

A Novel Approach for Image Encryption with Chaos-RNA

In today’s information society,image encryption technology is crucial to protecting Internet security.However,traditional image encryption algorithms have problems such as insufficient chaotic characteristics,insufficient randomness of keys,and insecure Ribonucleic Acid(RNA)encoding.To address these issues,a chaos-RNA encryption scheme that combines chaotic maps and RNA encoding was proposed in this research.The initial values and parameters of the chaotic system are first generated using the Secure Hash Algorithm 384(SHA-384)function and the plaintext image.Next,the Lühyperchaotic system sequence was introduced to change the image’s pixel values to realize block scrambling,and further disturbance is achieved through spiral index sequence to enhance encryption effectiveness.Subsequently,to obtain the final encrypted image,the diffusion is accomplished through different RNA encoding rules and operation rules corresponding to the chaotic sequence generated by an improved one-dimensional chaotic map(1DCM).Here innovatively propose four new RNA operation rules,increasing the difficulty of decryption.Simulation results demonstrate that the normalized pixel change rate(NPCR)and the unified average changed intensity(UACI)values of the tested encrypted images were 99.61%and 33.46%,respectively.The average ciphertext entropy value in the Red Green Blue(RGB)channels were 7.9986,7.991,and 7.991.Furthermore,this algorithm exhibits a low correlation coefficient and enhanced robustness.This encryption method effectively improves the security and reliability of image encryption compared to other similar techniques.

L-赖氨酸与谷氨酰胺转氨酶联合处理对低盐鸡肉糜凝胶保水及质构品质的影响

以低盐(含1%质量分数NaCl)鸡肉糜(low-salt chicken meat batter,LCMB)为对象,研究不同质量分数(0.25%、0.5%、0.75%、1.0%)L-赖氨酸与质量分数0.5%谷氨酰胺转氨酶(transglutaminase,TGase)联合处理对LCMB凝胶保水性(water holding capacity,WHC)、质构、水分流动性和分布、微观结构及蛋白质构象的影响。结果表明,TGase单独处理对LCMB凝胶的WHC无显著影响(P>0.05),但会显著提高凝胶的硬度(P<0.05);在添加TGase的情况下,随着L-赖氨酸含量的增加,LCMB凝胶的WHC、硬度、弹性、内聚性及咀嚼性均呈现升高的趋势。低场核磁共振、扫描电镜、拉曼光谱的结果分别显示,L-赖氨酸协同TGase处理能增加LCMB凝胶内部不易流动水的相对含量P21、降低自由水的相对含量P22,促进形成有序、致密、连续的凝胶三维网络结构,增加肉糜蛋白质中色氨酸残基、酪氨酸残基和脂肪族氨基酸残基的暴露。综上所述,L-赖氨酸结合TGase处理能通过影响LCMB凝胶的水分分布、微观结构及蛋白质构象,从而改善LCMB的凝胶品质。

Instruction Effects on L2 Pronunciation Improvement:a Critical Review of a Research Article

This is a critical review about the research Effects of instruction on L2 pronunciation development:A synthesis of 15 quasiexperimental intervention studies.During this research,Saito(2012)discovers the effects of instruction on L2(second language)pro nunciation development.Though this critical review,some implications and skillful research methods could be learned from this research.

Improvement of foreign gene expression in transgenic rice(Oryza sativa L.)by matrix attachment regions(MARs)

Matrix attachment regions or matrix associated regions (MARs) were special DNA sequences in chromatin of eukaryotic cells that tightly associated with the nuclear matrix or scaffold in vitro after a combination of nuclease digestion and extraction. They were also called scaffold attachment regions(SARs) . It was found that MARs could improve the expression level and the stability of foreign genes in transgenic plants. The reason might be that a transgene flanked by MARs was transmitted into the plant cells, the MARs would attach the nuclear

超高层空中L形钢连廊整体提升过程的减振控制与设计

针对钢结构连廊的整体提升,推导了TMD减小被提升结构风振响应的理论公式,采用Python编制了可视化TMD减振系统设计平台,对超高层空中L形钢连廊提升过程中的风振响应进行了分析,得到以下结论:1)基于TMD减振力学模型开发的减振设计程序,能够准确的对被提升结构进行TMD减振分析,并确定最优的TMD设计参数;2)地铁金融城项目的L形钢连廊在提升过程中,采用TMD减振技术后,对阵风引起的振动幅度减小35%,振动时间减小83.9%;3)TMD技术能够有效的控制风荷载作用下被提升结构的振动幅值和振动时间。

棉花秸秆无筛粉碎机的设计与试验

针对棉花秸秆因木质化程度较高、韧性强,还掺有棉絮,在有筛粉碎机粉碎过程中排料困难、筛片易堵塞等问题,设计了一种棉花秸秆无筛粉碎机,通过调整出料口面积来实现粉碎室内气体流量的改变,获得不同粉碎粒度的棉花秸秆成品;对粒度分级装置、粉碎刀辊等主要部件的结构进行了确定;阐述了粉碎过程中棉花秸秆的受力过程,确定了L改进型锤片的关键参数,对机具的L改进型锤片和抛送叶片进行了结构和排列设计。Fluent仿真分析结果表明:L改进型锤片相比直刀型锤片更有利于提高棉花秸秆在粉碎室内的流动性并在粉碎室内部形成更大的负压。以L改进型锤片数量、粉碎刀辊转速、出料口面积为试验因素,以棉花秸秆粉碎粒径合格率为试验指标,进行三因素三水平正交试验,确定影响棉花秸秆粉碎粒径合格率显著性的因素由大到小分别为:粉碎刀辊转速、出料口面积和L改进型锤片数量。确定较优参数组合为L改进型锤片数量140把,粉碎刀辊转速2660 r·min^(-1),出料口面积136500 mm^(2)。采用较优参数组合进行样机田间试验,测得棉花秸秆粉碎粒径合格率为93.7%,能够满足棉花秸秆粉碎机实际生产需要。

L-精氨酸高产菌的选育及基于代谢流量分布的育种机制

从分析钝齿棒杆菌(Corynebacterium crenatum)的精氨酸合成途径入手,提出了一种通过选育脯氨酸结构类似物抗性突变株以提高其精氨酸合成能力的育种思路。采用亚硝基胍(NTG)诱变处理出发菌株YD8(His-,SGr1.2 mg/mL,D-Argr15 mg/mL),经含15 mg/mL的脯氨酸结构类似物S-甲基半胱氨酸(S-MC)的抗性筛选获得精氨酸高产突变株YDM403(His-,SGr1.2 mg/mL,D-Argr15 mg/mL,S-MCr15 mg/mL),产酸水平可达29.4 g/L,较出发菌株YD8的产酸高出55.0%。通过代谢流量分布分析了菌株YD8和YDM403代谢网络的变化,结果表明,菌株YD8可能存在顺序反馈抑制作用,出发株YD8解除了Arg对Glu到Arg的反馈抑制,而YDM403又解除了Pro对Glu到Pro的反馈抑制,从而使中间物Glu累积量下降而对-αKG到Glu不再有反馈抑制,其通量提高,与此同时从Glu向Arg的代谢通量也相应增加。