高性能软相关同步技术在数据链抗干扰上的应用

数据链抗干扰中,由于长距离传输带来的信号衰减非常显著,提升低信噪比下的传输能力是最为基础的需求。针对低信噪比下数据同步的问题,仿真了不同软相关方案的同步性能,简化了软相关同步算法复杂度;同时,为满足不同场景下的通信需求,利用信号 SNR 作为判决条件,动态调整跟踪与同步方案。在 SOC 芯片上实现了动态软相关跟踪与同步方案,在简化了算法复杂度的情况下,性能仅损失 0.5 dB。

一种基于软相关的GNSS比特同步方法

GNSS接收机中因为比特同步错误而导致的导航电文提取失败和伪距计算错误等问题非常普遍。目前的比特同步算法主要是直方图法。其中,基于硬判决的直方图法应用较为广泛,主要是因为其实现方便,但在低载噪比下同步成功率太低,无法满足工程需求。因此,需要对低信噪比下的bit同步算法进行研究。本方案提出了直方图法与软相关结合的bit同步算法。首先,模拟产生在不同载噪比下的GNSS信号数据,它有20个比特边界。然后,采用两种算法进行比特同步。重复仿真多次,每次仿真采用随机的比特边界,得到每种算法在不同载噪比下的正确比特同步概率。分析仿真结果发现,比特同步的时间越长,各算法的正确概率越大。在低载噪比下,软相关方法远高于传统的直方图法。最后基于altera arriaV芯片完成了软相关的比特同步方案工程实现。

银洲湖西岸软土物理力学指标多元相关性研究

软土具有明显的区域特性、不确定性,通过土工试验结合数理分析方法分析研究各项力学变性指标与物理指标之间的多元线性回归分析,结合具体工程实例,建立多元线性方程,研究结果表明:压缩指标回归方程主要与土的密实程度指标有较大的相关性,力学指标与土的密实程度与状态指标有较大的联系。

软件构件化技术研究

能够象硬件一样，通过构件组合的方式构建软件系统，一直是计算机界多年来追求的方向。软件构件化技术是解决这个问题的关键。文中综述了笔者在软构件技术方面的研究成果，并就软构件研究的若干关键技术问题（软构件的集成、接口、通讯及嵌入）作了讨论。

现代汉族年轻女性“倒三角脸”与“方脸”下面部颅颌面软硬组织三维CT的测量研究

目的:探讨现代汉族年轻女性"倒三角脸"与"方脸"下面部颅颌面软硬组织量化标准及相互关系,为下面部轮廓改型提供理论依据。方法:测量15例现代汉族年轻女性下面部软硬组织形态学指标(倒三角脸7例,方脸8例),应用SPSS17.0进行统计学分析,分析两种脸型在下面部软硬组织上的区别。结果:1两种脸型下面宽、下面高、咬肌厚度、中面宽/下面宽、下面宽/下面高有显著性差异(P<0.01);2下面宽与咬肌厚度正相关,与下颌角角度负相关;下面高与下颌角角度正相关,与咬肌厚度负相关;下颌角角度与咬肌厚度负相关;3下面部软硬组织测量项目左右对称性较好,差异在正常范围内。结论:方脸与倒三角脸下面部软硬组织差异较大,横向差异以咬肌厚度差异为主,纵向以下面高差异为主。多数人通过肉毒素瘦咬肌结合隆颏术,可缩窄下面宽、延长下面高,使方脸向倒三角脸转变。该方法简单易行,患者接受度高,效果显著。

骨性Ⅲ类错(牙合)正颌手术前、后面部软、硬组织变化比率的三维研究

目的 :研究骨性Ⅲ类错(牙合)畸形患者面部软、硬组织三维方向上变化的相关性,以及手术前、后软、硬组织的变化比率,以期更好地对术后软组织外貌进行预测。方法:对20例骨性Ⅲ类错(牙合)畸形成人患者分别于术前2周及术后3个月进行颅面CT扫描和三维重建及面部软组织3D摄影成像,将采集的数据导入Dolphin软件,转换为三维面像数字化模型,建立三维测量坐标系(轴面、矢状面及冠状面),筛选19个软、硬组织标记点并进行测量、对比和配对,共12对。读取标记点的三维坐标(X、Y、Z),进行手术前、后的定点对比测量,采用SPSS 22.0软件包对测量数据进行统计学分析。结果:12对软、硬组织标志点在X轴即左右方向仅Pn/A、Gn'/Gn及Me'/Me存在相关性,在Y轴即上下方向仅Gn'/Gn存在相关性,在Z轴上所有软、硬组织配对点均存在相关性。除UL'/UI及UL/SPr外,均为高度相关。手术前、后,下颌的软、硬组织测量标志点的变化比率大于上颌。结论:骨性Ⅲ类错(牙合)畸形患者双颌手术前、后软、硬组织的变化主要集中于Z轴即前后向的变化,各软、硬组织配对标志点间呈线性相关关系,且下颌软、硬组织位移比率大于上颌。

骨性Ⅲ类错畸形患者双颌手术后软、硬组织的变化

目的:探讨骨性Ⅲ类错畸形患者双颌手术后软、硬组织变化的相关性、软组织厚度与软硬组织变化的相关性及软组织厚度的变化,以更好地预测术后软组织侧貌。方法:对26例骨性Ⅲ类错畸形成人患者进行锥形束CT(CBCT)扫描,用InVivo5软件将CBCT转化成头颅侧位片(cephalogram from CBCT,CCB),导入"几何画板"并建立坐标系,进行定点测量。采用SPSS17.0软件包对所有测量值进行统计学分析。结果:各软、硬组织标志点存在线性相关关系,下颌比上颌相关性强。Sn∶A=0.18∶1,UL∶Ui=0.31∶1,LL∶Li=0.80∶1,Si∶B=0.84∶1,Pg'∶Pg=0.90∶1。鼻底厚度、颏部厚度与相应软、硬组织变化无相关关系。唇部厚度与软、硬组织变化呈负相关关系。术后上唇变薄,下唇变厚。结论:软、硬组织变化呈线性相关关系,下颌软、硬组织位移比率大于上颌。鼻底及颏部软组织受硬组织移动影响小,唇部变化受硬组织影响大;唇部越薄,随硬组织移动性越好。

手术先行模式治疗骨性Ⅲ类患者软硬组织变化的分析研究

【目的】研究手术先行模式(Surgery-First Approach,SFA)治疗骨性Ⅲ类错合畸形前后的软硬组织变化以及相关性。方法选取近五年于青岛大学附属医院行SFA治疗的骨性Ⅲ类错合畸形患者20例,所有患者均行上颌LefortI型截骨术+双侧下颌支矢状骨劈开术(BSSRO),未行颏成形术。测量每位患者治疗前(T1)以及治疗结束(T2)的头颅侧位片,对近20个软硬组织相关标志点进行测量,并对硬组相应软组织点的变化进行相关性分析。结果在颌面部相应软硬组织的变化中,上颌硬组织变化较大,有统计学意义(P<0.05);软组织点变化较小(P>0.05),无统计学意义,与其相应的硬组织变化相关性差(r<0.6,P>0.05)。下颌软硬组织变化较大(P<0.001),有统计学意义。下颌唇部和颏部软硬组织变化呈高度的显著相关性(0.6<r<0.8,P<0.001),尤其下牙槽座点和颏部的软硬组织变化相关性较强(r>0.8,P<0.001)。结论骨性Ⅲ类患者经SFA治疗后,其软硬组织相关性表现为:上颌软硬组织变化相关性较差;下颌软硬组织变化有相关性,尤其下牙槽座点和颏部软硬组织变化呈高度显著相关性。

表面特征与软X射线掠入射光学散射

介绍了短波段掠入射表面散射线性模型,并且根据这个理论,分析计算了不同的表面特征对软X射线掠入射光学散射特性的影响。实验发现:随着粗糙度的增加、自相关长度的减小,软X射线掠入射光学散射越来越严重。

青少年骨性Ⅲ类错[牙合]软硬组织的三维相关性研究

目的本研究的目的是调查中国北方青少年骨性Ⅲ类错[牙合]畸形患者三维软组织面像与CBCT硬组织结构间测量值的相关性。方法本研究纳入20名北京地区青少年。通过对三维面像上14个点的定位,得出22个角度值与2个距离值;并同样测量CBCT上对应硬组织的9个角度值与3个距离值。所有项目由同一研究者测量两次,并计算其组内相关系数验证其可重复性。以Pearson相关性分析计算测量结果的软硬组织相关性。并在CBCT上测量相关点软组织厚度,以探索相关性的可能原因。结果与软组织下颌角点相关的测量项目可重复性一般。矢状向上软组织鼻旁点与硬组织A点相对鼻根点的位置关系有中等程度的相关性,上下颌骨的相对位置关系在软硬组织间有中到强的相关关系;垂直向上软组织左右下颌角,下颌平面角与相应的硬组织间有中到强的相关性,软组织前上面高及前下面高与相应的硬组织测量值及硬组织下颌平面角均表现出中等程度的相关性,鼻旁点软组织厚度小于鼻底点软组织厚度。结论软组织鼻旁点,软组织上下颌的相对位置关系,以及前上面高、前下面高的软组织测量指标都可以为相应的硬组织诊断提供较好的参考;然而与软组织下颌角点相关的测量值需要谨慎处理。

Architecture design of GPS software receiver and implementation of its acquisition algorithm with fine frequency estimation

The design of a global positioning system （GPS） software receiver is introduced. This design uses the concept of software radio, and it consists of the following parts： front-end, acquisition, tracking, synchronization, navigation solution and some assisting modules. In the acquisition module, the acquisition algorithm based on circular correlation is utilized. The input data and the local code are converted into the frequency domain by means of the fast Fourier transform （FFT）. After performing circular correlation, the initial phase of the C/A code can be obtained and the cartier frequency can be found in 1 kHz frequency resolution, which is too coarse to use for the tracking loop. In order to improve the frequency resolution, the fine frequency estimation through a phase relationship is then achieved, by which, the frequency resolution is improved dramatically. Experiments show that the inaccuracy of the carrier frequency can be estimated within a few hertz by the fine frequency estimation method, and the fine frequency attained can be directly used for the tracking loop.

A FRAMEWORK TO MEASURE CLASS COHESION

Classes are the basic modules in Object-Oriented (OO) software, which consist of attributes and methods. Thus, in OO environment, the cohesion is mainly about how tightly the attributes and methods of classes cohere with each other. This letter discusses the relationships between attributes and attributes, attributes and methods, methods and methods of a class,and the properties of these relationships. Based on these properties, the letter proposes a new framework to measure the cohesion of a class. The approach overcomes the limitations of previous class cohesion measures, which consider only one or two of the three relationships in a class.

Improved Circular Correlation Methods for Acquisition in Software GPS Receiver

In this paper the authors explore the Global Positioning System （GPS） signal acquisition and tracking algorithms used in software GPS receiver. Acquisition time is the most important parameter in evaluating the performance of a software GPS receiver in terms of its speed. A trade-off study is done to seek a good balance between the acquisition accuracy and the processing time. The frequency-domain acquisition method by circular correlation, used in a software GPS receiver, has been improved by studying the power spectrum of the Coarse Acquisition （C/A） code alone. The analysis of C/A code reveals that its power spectrum is symmetrical; hence only half the points are required to perform circular correlation. Besides, either half of the spectrum is asymmetrical where a larger amount of power is concentrated in almost one-quarter of the spectrum on its either sides. This further reduces the number of points used to perform correlation. Comparative results of MATLAB simulation of full-size, half-size and quarter-size circular correlation done on actual data stored on hard disk are provided, and they agree with those obtained using GPS receiver. Further reduction in acquisition time has been achieved by investigating the effect of length of the noncoherent pre-integration period. The improved acquisition methods pave way for further development of new algorithms to enhance software GPS receiver performance.

Some Psychosocial Problems of Adolescents in Some Ghanaian Senior High Schools

This research investigated whether there was a significant relationship between the problems of loneliness, inferiority, and identity confusion. Also, to test whether there was a significant relationship between problems of adolescents and their ages and sexes and to ascertain whether there will be a significant difference in sex with regards to these problems, 240 adolescent students from four Senior High Schools were sampled as respondents for the study. Correlations and t-test were used for analyses by employing Statistical Package for Social Sciences （SPSS） version 16. From the results, it appeared that there were highly significant positive correlations existing between the problems. This suggests that the more an adolescent experiences a problem, the higher will he/she experience another problem. Also, it appeared that among the three problems, inferiority had a significant relationship with sex whereas all the problems had a positive significant relationship with age. This suggests that the older an adolescent is, the more severe will he/she experience a problem. Finally, girls tend to experience inferiority more than their male counterparts. This finding also suggested that although problems of adolescents may differ with regards to sex, they are not isolated and therefore multi-factorial in nature.

Role of Metacognition in Mathematical Problem Solving Process of Permutations and Combinations--Basic Study for CAI Software Development

When solving a mathematical problem, we sometimes encounter a situation where we can not reach a correct answer in spite of acquiring knowledge and formula necessary for the solution. The reason can be attributed to the lack in metacognitive abilities. Metacognitive abilities consist of comparing the difficulty of problem with own ability, proper plan of solution process, and conscious monitoring and control of solution process. The role and importance of metacognitive ability in mathematical problem solving of permutations and combinations was explored. Participants were required to solve five practical problems related to permutations and combinations. For each problem, the solution process was divided into： （1） understanding （recognition） of mathematical problem; （2） plan of solution; （3） execution of solution. Participants were also required to rate the anticipation whether they could solve it or not, and to rate the confidence of their own answer. According to the total score of five problems, the participants were categorized into the group of the high test score and the group of the low test score. As a result, at the plan and the execution processes, statistically significant differences were detected between the high and the low score groups. As for the rating on the anticipation of result and the confidence of own answer, no significant differences were found between both groups. Moreover, the relationship between the score of plan process and the score of execution process was statistically correlated. In other words, the more proper the plan process was conducted, the more proper solution the participants reached. In such a way, the importance of metacognitive ability in the solving process, especially the plan ability, was suggested.

The effects of corporate governance compliance on market valuation in Malaysia

This study investigates the effects of corporate governance compliance on market valuation in Malaysia using a sample of 164 companies listed on the Main Board in Bursa Malaysia from 5 different industries （consumer, trading ＆ services, industrial, constructions and properties） within 2001 to 2005. Throughout, this study will use correlation and regression analysis in the SPSS software to determine the effects of corporate governance practices on Market Valuation. In analyzing firms＇ market valuation, we will use the Tobin＇s Q formula and for the corporate governance compliance, we will look at 4 criteria to compare with market valuation, which are （1） Board of Director＇s composition, （2） Board of Director＇s remuneration （salaries）, （3） Board of Director＇s training and development, （4） Board of Director＇s meeting. In order to determine the effects between the corporate governance compliance and market valuation, we will use regression analysis. Based on the correlation analysis, the first null hypothesis must be rejected and the alternative hypothesis is accepted, in which dependent variable and independent variables are significantly correlated with BOD remuneration and BOD training availability. Overall, there is a significant relationship between Tobin＇s Q and independent variables （BOD remuneration and BOD training）. This study also recommends that for the company who did not comply with the code, they should follow the best practice because it will be a pivotal weapon in facing with the fierce competition in era globalization.

The Body in Old Age and Dependency： A Territory of Threat and Uncertainty

This paper explores the image of the body in physically dependent elderly men and women and the way in which this image reconfigures their identity creating new meanings. In old age, the body becomes related with illness, with disablement and with its own material finiteness. Representations of the body are thus constructed around pain, deficiency, and fragility. The research was carried out from a qualitative perspective, performing in-depth interviews, with participant observation and a subject ID card as data collecting techniques. The identity of the interviewees who consented to be recorded was protected. The data were analyzed constructing concepts and theoretical and empirical categories with the support of the Etnograph V.5 software for qualitative data. The findings reflect discourses on the body that turn on its deterioration and limitations that prevent old people from functioning adequately in life. Metaphors were identified telling of a sense of＂deteriorated identity＂; most participants saw themselves as ＂a burden＂. They also showed symptoms of annoyance and shame regarding their sick or fragile bodies, as well as a constant memory of the healthy or ＂ideal＂ body of the past, which is hegemonic in our culture.

A crystal plasticity coupled damage constitutive model of high entropy alloys at high temperature

A crystal plasticity constitutive model of high-entropy alloys(HEAs)coupled with damage evolution equation at high temperature is developed.To simulate the degraded load-carrying capacity of HEAs caused by microdefects,a phenomenological damage evolution equation is proposed based on the compression experiments at different temperatures.The established model is used to simulate the stress softening phenomenon of polycrystalline AlCrCuFeNi-based HEAs,which is highly dependent on the strain rate and temperature.Compared with the experimental data,the proposed model is able to accurately describe the stress-strain relationship of HEAs.