非自治的非经典反应扩散方程的一致吸引子     

王素云 《甘肃高师学报》2009,14(2)

讨论并得到了非自治的非经典反应扩散方程的一致(关于时间符号)吸引子的存在性,且对方程中的外力项使用了比文[1]中所要求的平移紧的条件弱的条件,即normal函数.  相似文献   

基于新型自适应遗传算法的直线感应电机的优化设计(英文)     

庄英超  余海涛  夏军  胡敏强 《东南大学学报》2009,25(2):203-207

为了提高直线感应电机的力能指标,提出一种新型自适应遗传算法,并对直线感应电机进行了优化设计.采用佳点集理论对遗传算法的初始化种群进行均匀设计,提高了遗传算法的优化效率.同时利用sigmoid函数改进了交叉概率和变异概率,使交叉率和变异率按照个体的适应度在平均适应度和最大适应度之间随sigmoid曲线进行非线性调整.在分析直线感应电机与旋转电机物理结构差异的基础上,得到考虑边端效应的直线感应电机的稳态性能,并给出直线感应电机力能指标的优化模型.通过对优化后的设计方案与原设计方案的比较发现:直线感应电机的力能指标显著提高,验证了方法的有效性.  相似文献   

基于混合链编码二进制图像的压缩和重构     

王永强  李好  张婷 《唐山学院学报》2010,(3):34-36,39

用一种先进的混合链编码算法对二进制图像进行压缩和重构,该算法包含了无损和有损两个部分,并利用这一算法对图像轮廓进行处理,生成大量的链节点数据,然后根据(n10,5)的规则进行编码,可实现很高的压缩比。对于有损部分,引入了一种新的线性处理技术,既平滑了图像轮廓,又保持了很高的图像质量。实验结果表明,该方法优于其它链编码方法 ,包括FCC,DCC-8和L&Z。另外,此方法的压缩比明显大于WinZip,JBIG1和JBIG2等标准的压缩比。  相似文献   

Assessing Measurement Invariance in Multiple-Group Latent Profile Analysis     

Margarita Olivera-Aguilar  Samuel H. Rikoon 《Structural equation modeling》2018,25(3):439-452

The study of measurement invariance in latent profile analysis (LPA) indicates whether the latent profiles differ across known subgroups (e.g., gender). The purpose of the present study was to examine the impact of noninvariance on the relative bias of LPA parameter estimates and on the ability of the likelihood ratio test (LRT) and information criteria statistics to reject the hypothesis of invariance. A Monte Carlo simulation study was conducted in which noninvariance was defined as known group differences in the indicator means in each profile. Results indicated that parameter estimates were biased in conditions with medium and large noninvariance. The LRT and AIC detected noninvariance in most conditions with small sample sizes, while the BIC and adjusted BIC needed larger sample sizes to detect noninvariance. Implications of the results are discussed along with recommendations for future research.  相似文献   

五元阵雷达信号的数学模型分析     

詹亮 《黑龙江科技信息》2013,(26):35-35,38

本文针对雷达信号方向侦测问题,首先给出对二元天线阵的简化模型,并建立了五元圆形天线阵的各相位间相位差异的数学模型。文章利用工程数据中各频率下的时域相位中的测量结果对模型进行分析和检验,并得出了较满意的值。  相似文献   

Neuromuscular,metabolic and hormonal profiles of young tennis players and untrained boys     

Antti Mero  Laura Jaakkola  Paavo V. Komi 《Journal of sports sciences》2013,31(2):95-100

This study compared the neuromuscular, metabolic and hormonal profiles of trained prepubescent tennis players and an untrained group. The boys in the experimental group (n = 9; mean age ± S.D. = 11.4 ± 0.5 years) had participated in tennis training for 2.3 ± 1.0 years and the boys in the control group (n = 9; mean age ± S.D. = 10.9 ± 0.4 years) were normal active volunteers. The tennis players were found to be physically more active than the controls when the comparison was made for either 1 year (4.9 ± 1.8 vs 2.6 ± 2.5 times per week; P<0.05) or for 1 week (3.4 + 1.2 vs 0.4 ± 0.5 times; P < 0.001) preceding the tests. Choice reaction time was significantly (P <0.01) shorter in the experimental group (258 ± 16 ms) than in the control group (344 + 81 ms). Dropping height in the best drop jump was significantly (P< 0.05) higher in the tennis players (0.46 + 0.19 m) than in the control boys (0.27 ± 0.10 m). The tennis players had significantly lower oxygen consumption at the ‘anaerobic threshold’ than the controls (P < 0.05). There were no significant differences between the groups in serum hormone levels. The small differences that existed may have been caused by actice participation in sport by the tennis players.  相似文献   

Gold Medal Volleyball: The Training Program and Physiological Profile of the 1984 Olympic Champions     

Carl M. McGown  Robert K. Conlee  Anthony A. Sucec  Michael J. Buono    William Phillips 《Research quarterly for exercise and sport》2013,84(2):196-200

Abstract

This study focused on the differences between experienced and inexperienced physical education teachers' approaches to planning, low inference indicators of teaching behavior during instruction, and global variables from the Beginning Teacher Evaluation Study. It was found experienced teachers asked many more questions before they began planning than did inexperienced teachers. Experienced teachers' plans reflected a concern about contingencies that might arise during instruction, whereas inexperienced teachers' plans did not. Interaction analysis and codings of student engagement showed marked differences between experienced and inexperienced teachers. Judging the qualities of experienced and inexperienced teachers also showed important differences. These sources of data are interrelated and give a vivid picture of how experienced and inexperienced teachers differ in accomplishment of instruction. The findings are discussed in terms of what they may mean for teacher development programs.  相似文献   

Personal ontologies: Generation of user profiles based on the YAGO ontology     

Silvia Calegari  Gabriella Pasi 《Information processing & management》2013

Personalized search is aimed at tailoring the search outcome to users; to this aim user profiles play an important role: the more faithfully a user profile represents the user interests and preferences, the higher is the probability to improve the search process.  相似文献   

Correlation of Cord Blood Lipid Heterogeneity in Neonates with Their Anthropometry at Birth     

Chandrika D. Nayak  Vaibhav Agarwal  Dinesh M. Nayak 《Indian journal of clinical biochemistry : IJCB》2013,28(2):152-157

Objective: Fetus with intrauterine stress may exhibit programmed changes that can alter its metabolism and bear severe risk for diseases in adult life. The current study was designed to assess the correlation between cord blood lipid profile with the anthropometric data in neonates. Materials and methods: 146 newborn babies born at Dr. T M A Pai Hospital, Udupi were screened and their birth weight, length, head circumference and abdominal circumference were noted at birth. Umbilical cord blood samples were analyzed for total cholesterol, triglycerides (TG), high density lipoprotein (HDL) and low density lipoprotein (LDL). Infants were also grouped further based on gestational age (GA) and sex-adjusted birth weight percentiles into three groups i.e. Small for gestational age (SGA), Appropriate for gestational age (AGA) and Large for gestational age (LGA) for comparison of their lipid profiles. Inclusion criteria were normal fetal heart rate at birth and an APGAR score >7. Statistical significance of relation between lipid profile and anthropometry was done using ANOVA and Pearson correlation coefficient. Results: Triglycerides were significantly higher in babies with higher ponderal index (PI) than those with lower PI (P = 0.011). The TG level of SGA babies were significantly higher as compared to AGA group (P = 0.001). The LDL levels in neonates with higher abdominal circumference were significantly lower than those with lower AC (P = 0.019). Mean HDL levels were higher in neonates with larger AC, but not statistically significant. Maternal BMI had no influence on neonates’ lipid profile. Conclusion: Abnormal intrauterine milieu created by maternal changes during gestation may bear a profound impact on lipid metabolism in neonates, which may account for their differences in lipid profile and anthropometry at birth.  相似文献   

大学物理动生电动势计算公式教法探析     

李启成 《鸡西大学学报》2004,4(6):41-42

在比较公式ε=Blv和d■=■·d■的联系和区别的基础上,对公式d■■·d■的应用进行了较为细致的分析。  相似文献