北斗高精度定时型用户机关键技术及应用研究

基于此,本文将简单分析北斗高精度定时型用户机关键技术,并深入探讨该技术的具体应用,希望研究内容能够给相关从业人员以启发。

乙型肝炎病毒SYBR GreenⅠ实时荧光定量PCR方法的建立及临床应用

目的建立 SYBR Green I实时荧光定量 PCR检测乙型肝炎病毒 DNA的快速方法，并探讨其临床应用价值。方法根据GenBank公布的Hepatitis B virus gp1基因序列设计引物，建立SYBR Green I实时荧光定量PCR，并对反应体系和扩增程序进行优化。定量标准品通过基因克隆方法获得，同时以浙江省夸克公司 HBV DNA定量检测试剂盒作对照，应用于随机选取的100份乙型肝炎患者血清检测。结果 SYBR Green I 实时荧光定量 PCR 检出限范围为5＆#215;102 copies／ml～5＆#215;108 copies／ml，HBV DNA浓度与CT值有良好线性关系，无交叉反应，整个过程仅需2.5 h。在随机抽取的100份临床标本应用中，与浙江省夸克公司的 HBV荧光定量 PCR检测试剂相比，建立的 SYBR Green I实时荧光定量PCR体系灵敏度100％，特异度92.5％。结论 SYBR Green实时荧光定量PCR快速、简便、灵敏度高、特异度强，可用于乙型肝炎患者病情监测，有效指导临床用药，准确评价 HBV感染者的病情。

数字化核脉冲定时方法研究

定时电路是核电子学中检出时间信息的模拟电路的基本单元,包括前沿定时、过零定时、恒比定时及幅度和上升时间补偿定时;与模拟定时电路相比,数字定时电路拥有许多优点:一是输入信号的前端数字化,大幅简化了模拟电路;二是数字信号的处理分析,根据测试的目的从采样信号中提取所需要的信息(幅度、时间)。论文以MATLAB为工具,探讨数字化恒比定时和一种改进型前沿定时。

黑客的类型

为了达到个人目的。通过在网络上设置陷阱，或事先在设计的软件中置入逻辑炸弹或后门程序，或在网络维护的时候置入逻辑炸弹或后门程序，在特定的时间或特定条件下，根据需要或干扰网络正常运行或致使生产线和网络完全陷入瘫痪状态。

切丝机尾料装置的设计与应用

本文通过对SQ31X系列切丝机在生产尾料时出现绒丝的情况进行分析,自主设计一种投入少、简单易行且成效快的装置。减少了物料的生产损耗,提高了物料的实际利用率,同时回避更改切丝机控制程序需要依赖于设备厂家的问题。对于其他型号的切丝机同样具有推广的价值。

Dynamical analysis for a malware propagation model in wireless sensor network

The threat of malware in wireless sensor network has stimulated some activities to model and analyze the malware prevalence.To understand the dynamics of malware propagation in wireless sensor network,we propose a novel epidemic model named as e-SEIR(susceptible-exposed-infectious-recovered)model,which is a set of delayed differential equations,in this paper.The model has taken into account the following two factors:1 Multi-state antivirus measures;2 Temporary immune period.Then,the stability and Hopf bifurcation at the equilibria of linearized model are carefully analyzed by considering the distribution of eigenvalues of characteristic equations.Both mathematical analysis and numerical simulations show that the dynamical features of the proposed model rely on the basic reproduction number R0 and time delayτ.This novel model can help us to better understand and predict the propagation behaviors of malware in wireless sensor networks.

EFFECT OF TIME AND ENVIRONMENT ON THE DIMENSION PRECISION AND MASS OF LOM PROTOTYPES

The effect of time and environment on the dimension precision and mass of LOM prototypes was experimentally investigated.It is to identify the stability of the dimension of LOM prototypes after forming.The results show that the dimension and the mass tendency to grow,which is mainly caused by elastic recovery and moisture absorption and is characterized principally by the growth of Z dimension.Self restraint can be a significant factor to influence Z growth of LOM prototypes.

A novel mathematical model on Peer-to-Peer botnet

Peer-to-Peer （P2P） botnet has emerged as one of the most serious threats to lnternet security. To effectively elimi- nate P2P botnet, a delayed SEIR model is proposed,which can portray the formation process of P2P botnet. Then, the local stability at equilibria is carefully analyzed by considering the eigenvalues＇ distributed ranges of characteristic equations. Both mathematical analysis and numerical simulations show that the dynamical features of the proposed model rely on the basic re- production number and time delay r. The results can help us to better understand the propagation behaviors of P2P botnet and design effective counter-botnet methods.

PRICES OF ASIAN OPTIONS UNDER STOCHASTIC INTEREST RATES

Asian options are the popular second generation derivative products and embedded in many structured notes to enhance upside performance.The embedded options,as a result,usually have a long duration.The movement of interest rates becomes more important in pricing such long-dated options.In this paper,the pricing of Asian options under stochastic interest rates is studied.Assuming Hull and White model for the interest rates,a closed-form formula for geometric-average options is derived.As a by-product,pricing formula is also given for plan-vanilla options under stochastic interest rates.

Molecular characterization and expression profiles of four transformer-2 isoforms in the Chinese mitten crab Eriocheir sinensis

The transformer-2(tra-2) gene plays a key role in the regulatory hierarchy of sexual differentiation in somatic tissues and in the germline of Drosophila melanogaster.In this study,sequences and expression profiles of tra-2 in the Chinese mitten crab Eriocheir sinensis were characterized.Four tra-2 isoforms,designated as Estra-2a,Estra-2b,Estra-2c,and Estra-2d,were isolated.They all contained an RNA-recognition motif(RRM) and a linker region,which shared high similarity with other reported tra-2s.Sequence analysis revealed that Estra-2a,Estra-2b and Estra-2c are encoded by the same genomic locus and are generated by alternative splicing of the pre-mRNA.Compared with the other three isoforms,Estra-2d lacks the RS2 domain.Quantitative real-time PCR showed that all four isoforms were highly expressed in the fertilized egg,and in the 2-4 cell and blastula stages compared with larval stages(P<0.01),suggesting their maternal origin in early embryonic developmental stages.Notably,Estra-2a was highly expressed in male somatic tissues,while Estra-2c was significantly highly expressed in the ovary.These results suggest that Estra-2c is involved in sexual differentiation of the Chinese mitten crab.Our findings provide basic information for further functional studies of the tra-2 gene/protein in this species.

A novel stabilization approach for small signal disturbance of power system with time-varying delay

Small signal instability may cause severe accidents for power system if it can not be dear correctly and timely. How to maintain power system stable under small signal disturbance is a big challenge for power system operators and dispatchers. Time delay existing in signal transmission process makes the problem more complex. Conventional eigenvalue analysis method neglects time delay influence and can not precisely describe power system dynamic behaviors. In this work, a modified small signal stability model considering time varying delay influence was constructed and a new time delay controller was proposed to stabilize power system under disturbance. By Lyapunov-Krasovskii function, the control law in the form of nonlinear matrix inequality （NLMI） was derived. Considering synthesis method limitation for time delay controller at present, both parameter adjustment method by using linear matrix inequality （LMI） solver and iteration searching method by solving nonlinear minimization problem were suggested to design the controller. Simulation tests were carried out on synchronous-machine infinite-bus power system. Satisfactory test results verify the correctness of the proposed model and the feasibility of the stabilization approach.

Lyapunov-Krasovskii functional based power system stability analysis in environment of WAMS

In order to analyze power system stability in environment of WAMS(wide area measurement system),a new steady state stability model with time-varying delay was proposed for power system.The factors of exciter and power system stabilizer with delay were introduced into analytical model.To decrease conservativeness of stability analysis,an improved Lyapunov-Krasovskii functional was constructed,and then a new delay-dependent steady state stability criterion for power system,which overcomes the disadvantages of eigenvalue computation method,was derived.The proposed model and criterion were tested on synchronous-machine infinite-bus power system.The test results demonstrate that Lyapunov-Krasovskii functional based power system stability analysis method is applicable and effective in the analysis of time delay power system stability.

趣谈:黑客之“罪”七大类

1.恶作剧型:喜欢进入他人网站,以删除某些文字或图像、篡改网址、主页信息来显示自己的厉害,此做法多为增添笑话自娱或娱人。 或者进入他人网站内,将其主页内商品资料内容、价格作降价等大幅度修改,使消费者误以为该公司的商品便宜廉价而大量订购,从而产生Internet订货纠纷。

黑客的特征及防御策略

世界各地对黑客的“定义”都不尽相同。按照东方人的习惯通常对黑客一词还有“侠”的含意。日本1998年新出版的《新黑客字典》把黑客定义为:“喜欢探索软件程序奥秘、并从中增长其个人才干的人。他们不像绝大多数电脑使用者,只规规矩矩地了解别人指定了解的狭小部分知识。” 1998年夏季,因印尼华人妇女惨遭印尼暴徒有组织的强暴,而激怒了中国黑客奋起袭击并破坏印尼诸点站的事例,

Antiviral Activity of Recombinant Cyanovirin-N against HSV-1

In this study,a standard strain of HSV-1 (strain SM44) was used to investigate the antiviral activity of the recombinant Cyanovirin-N (CV-N) against Herpes simplex virus type 1 (HSV-1) in vitro and in vivo.Cytopathic effect (CPE) and MTT assays were used to evaluate the effect of CV-N on HSV-1 in Vero cells.The number of copies of HSV-DNA was detected by real-time fluorescence quantitative PCR (FQ-PCR).The results showed that CV-N had a low cytotoxicity on Vero cells with a CC50 of 359.03±0.56 μg/mL,and that it could not directly inactivate HSV-1 infectivity.CV-N not only reduced the CPE of HSV-1 when added before or after viral infection,with a 50% inhibitory concentration (IC50) with 2.26 and 30.16μg/mL respectively,but it also decreased the copies of HSV-1 DNA in infected host cells.The encephalitis model for HSV-1 infection was conducted in Kunming mice,and treated with three dosages of CV-N (0.5,5 & 10 mg/kg) which was administered intraperitoneally at 2h,3d,5d,7d post infection.The duration for the appearance of symptoms of encephalitis and the survival days were recorded and brain tissue samples were obtained for pathological examination (HE staining).Compared with the untreated control group,in the 5mg/kg CV-N and 10mg/kg CV-N treated groups,the mice suffered light symptoms and the number of survival days were more than 9d and 14d respectively.HE staining also showed that in 5mg/kg CV-N and 10mg/kg CV-N treated groups,the brain cells did not show visible changes,except for a slight inflammation.Our results demonstrated that CV-N has pronounced antiviral activity against HSV-1 both in vitro and in vivo,and it would be a promising new candidate for anti-HSV therapeutics.

Matched Field Localization Based on CS-MUSIC Algorithm

The problem caused by shortness or excessiveness of snapshots and by coherent sources in underwater acoustic positioning is considered.A matched field localization algorithm based on CS-MUSIC(Compressive Sensing Multiple Signal Classification) is proposed based on the sparse mathematical model of the underwater positioning.The signal matrix is calculated through the SVD(Singular Value Decomposition) of the observation matrix.The observation matrix in the sparse mathematical model is replaced by the signal matrix,and a new concise sparse mathematical model is obtained,which means not only the scale of the localization problem but also the noise level is reduced;then the new sparse mathematical model is solved by the CS-MUSIC algorithm which is a combination of CS(Compressive Sensing) method and MUSIC(Multiple Signal Classification) method.The algorithm proposed in this paper can overcome effectively the difficulties caused by correlated sources and shortness of snapshots,and it can also reduce the time complexity and noise level of the localization problem by using the SVD of the observation matrix when the number of snapshots is large,which will be proved in this paper.

Translating Linear Temporal Logic Formula s into Automata

To combat the well-known state-space explosion problem in Prop ositional Linear T emp o- ral Logic （PLTL） model checking, a novel algo- rithm capable of translating PLTL formulas into Nondeterministic Automata （NA） in an efficient way is proposed. The algorithm firstly transforms PLTL formulas into their non-free forms, then it further translates the non-free formulas into their Normal Forms （NFs）, next constructs Normal Form Graphs （NFGs） for NF formulas, and it fi- nally transforms NFGs into the NA which ac- cepts both finite words and int-mite words. The experimental data show that the new algorithm re- duces the average number of nodes of target NA for a benchmark formula set and selected formulas in the literature, respectively. These results indi- cate that the PLTL model checking technique em- ploying the new algorithm generates a smaller state space in verification of concurrent systems.

Farmers＇ Perceived Impact of Fair Trade： The Case of Costa Rica

The perceived usefulness of Fair Trade influences both its effectiveness and farmers＇ long-term participation. The aim of this paper is to measure the perceived economic, social and environmental impact of Fair Trade by farmers in Costa Rica. One hundred farmers were interviewed, and their perceived change in living and working conditions due to Fair Trade participation was measured through a t-test analysis. The sample characters＇ influence on the perceived change was also measured, adopting a regression model and a t-test. The results showed a positive perception of the impact of Fair Trade, with a particularly strong perceived improvement in the farmers＇ technical, economic and managerial skills. There was relatively less perceived change in the environmental, educational and sanitary conditions. The results showed the need for Fair Trade to better adjust its strategy to the expectations of the farmers＇ communities.

Multiple-Relaxation-Time Lattice Boltzmann Approach to Richtmyer-Meshkov Instability

The aims of the present paper are twofold. At first, we further study the Multiple-Relaxation-Time （MRT） Lattice Boltzmann （LB） model proposed in [Europhys. Lett. 90 （2010） 54003]. We discuss the reason why the Gram Schmidt orthogonalization procedure is not needed in the construction of transformation matrix M; point out a reason why the Kataoka-Tsutahara model [Phys. Rev. E 69 （2004） 035701（R）] is only valid in subsonic flows. The yon Neumann stability analysis is performed. Secondly, we carry out a preliminary quantitative study on the Richtmyer- Meshkov instability using the proposed MRT LB model. When a shock wave travels from a light medium to a heavy one, the simulated growth rate is in qualitative agreement with the perturbation model by Zhang-Sohn. It is about half of the predicted value by the impulsive model and is closer to the experimental result. When the shock wave travels from a heavy medium to a light one, our simulation results are also consistent with physical analysis.

Hemihepatic versus total hepatic inflow occlusion during hepatectomy:A systematic review and meta-analysis

AIM： To evaluate the clinical outcomes of patients undergoing hepatectomy with hemihepatic vascular occlusion （HHO） compared with total hepatic inflow occlusion （THO）. METHODS： Randomized controlled trials （RCTs） co- mparing hemihepatic vascular occlusion and total he- patic inflow occlusion were included by a systematic literature search. Two authors independently assessed the trials for inclusion and extracted the data. A meta- analysis was conducted to estimate blood loss, transfu- sion requirement, and liver injury based on the levels of aspartate aminotransferase （AST） and alanine arni- notransferase （ALT）. Either the fixed effects model or random effects model was used. RESULTS- Four RCTs including 338 patients met the predefined inclusion criteria. A total of 167 patients were treated with THO and 171 with HHO. Metaanalysis of AST levels on postoperative day 1 indicated higher levels in the THO group with weighted mean dif- ference （WMD） 342.27; 95% confidence intervals （CI） 217.28-467.26; P = 0.00001; I2 = 16%. Meta-analysis showed no significant difference between THO group and HHO group on blood loss, transfusion requirement, mortality, morbidity, operating time, ischemic duration, hospital stay, ALT levels on postoperative day 1, 3 and 7 and AST levels on postoperative day 3 and 7. CONCLUSION： Hemihepatic vascular occlusion does not offer satisfying benefit to the patients undergoing hepatic resection. However, they have less liver injury after liver resections.