两种应用场景下NDVI时间序列数据拟合方法研究

植被覆盖指数（NDVI）时间序列数据集包含地表植被的长势、生长周期、时空变化等信息,其拟合重建结果可应用于物候信息提取、生态质量评价、人类活动扰动识别、覆被变化动态监测等方面。基于TIMESAT软件,选取物候参数提取和扰动识别2个应用场景,结合地面站点数据和Jacknife法模拟数据,对比分析非对称高斯函数拟合法（AG法）、双Logistic函数拟合法（D-L法）和Savitzky-Golay滤波法（S-G法）3种方法的拟合效果。结果表明：（1）3种方法拟合重建后提取的生长开始时间（SOS）、生长结束时间（EOS）、生长周期（LOS）等物候参数接近站点数据,AG法和D-L法保持NDVI时序曲线整体变化特征的能力较强,提取的SOS和EOS更接近站点数据;（2）人类活动扰动识别应用场景中,S-G法在滤波时能够最大限度地保留时序曲线细节变化,恢复速率相关系数达到0.618,回归估计标准差低于AG法和D-L法,因此识别精度最优。     

基于谱特征的数字信号调制方式识别

根据谱相关函数理论和对常见的数字信号的谱相关函数及特征平面图分析,提出了几种可用于调制方式识别的特征参数,讨论了利用这些特征参数进行调制识别的方法和过程。仿真表明,这种方法有很好的识别效果。     

相对湿度、温度对胶合板甲醛释放的影响

测试了不同相对湿度、温度条件下密闭环境舱中胶合板释放的甲醛浓度,研究了相对湿度和温度对胶合板甲醛释放的影响规律.结果发现:开始3h内密闭舱内甲醛浓度迅速增加,之后7~8h甲醛浓度趋于平衡;相对湿度升高20%,密闭舱内甲醛平衡浓度增加了1.1~1.3倍;温度升高5℃,甲醛平衡浓度增加了1.3~2.5倍;利用变装载度法,求解了胶合板甲醛初始可释放浓度C_m,0、扩散系数D_m和界面气固分配系数K,探讨了相对湿度、温度对各释放参数的影响,构建了相对湿度与温度影响参数模型,模型预测了不同环境条件下的胶合板甲醛释放参数,预测值与实验结果吻合良好.     

不同因素对特高压变压器励磁涌流的影响

为了研究特高压变压器产生的励磁涌流对特高压变压器差动保护的影响,运用MATLAB/SIMULINK,建立了特高压变压器仿真模型,参数按照晋东南—南阳—荆门1000kV特高压交流试验示范工程中的相关数据设置。利用所建立的模型进行空载投切的仿真,分析了合闸角与剩磁对励磁涌流的影响。仿真结果验证了控制合理的合闸角与剩磁可以限制励磁涌流的出现,从而避免特高压变压器差动保护误动,为提出新的识别励磁涌流判据提供了理论基础。     

Adsorption of phosphate ions from water using a novel cellulose-based adsorbent

A novel cellulose-based adsorbent, iron(III)-coordinated amino-functionalised poly(glycidylmethacrylate)-grafted cellulose [Fe(III)–AM-PGMACell] was developed for the removal of phosphate from water and wastewater. The scanning electron micrograph showed that AM-PGMACell has a rougher surface than cellulose and the adsorption of Fe(III) on AM-PGMACell made the surface even rougher. Infrared spectroscopy revealed that amino groups on the surface of AM-PGMACell complexed with Fe(III) played an important role in the removal of phosphate from solutions. X-Ray diffraction patterns showed a decrease in crystallinity after graft copolymerisation onto cellulose. The effects of contact time, initial sorbate concentration, pH, agitation speed, dose of adsorbent and temperature on the removal process were investigated. Maximum removal of 99.1% was observed for an initial concentration of 25 mg·L ^?1 at pH 6.0 and an adsorbent dose of 2.0 g·L ^?1. A two-step pseudo-first-order kinetic model and Sips isotherm model represented the measured data very well. Complete removal of 11.6 mg·L ^?1 phosphate from fertiliser industry wastewater was achieved by 1.6 g·L ^?1 Fe(III)–AM-PGMACell. The adsorbent exhibited very high reusability for several cycles. Overall, the study demonstrated that Fe(III)–AM-PGMACell can be used as an efficient adsorbent for the removal and recovery of phosphate from water and wastewater.     

Smokeless tobacco extract impairs iron homeostasis in rats and human hepatoma,HepG2 cells

Tobacco exposure may alter homeostasis of iron (Fe), one of the most abundant and essential transition metals in the body. In this study, the effect of aqueous extract of smokeless tobacco was evaluated on Fe homeostasis in rats and human hepatoma, HepG2 cells. Our findings suggested that tobacco consumption even at low doses impairs Fe homeostasis leading to Fe deficiency anemia. Significant alterations were noted with respect to hematological parameters and expression patterns of selected intestinal Fe-transporters, Fe-binding proteins, and Fe-regulatory hormone, hepcidin. Impairment in the hepatic and renal antioxidant defense system was also observed in the treated rats. Histopathological studies revealed cirrhosis of liver and goblet cell hyperplasia of small intestine. Further, analysis of hepcidin promoter and its expression along with ferritin (expression and ELISA) in HepG2 cells demonstrated an enhanced expression of both the genes resulting in sequestration of Fe in treated cells, thus indicating systemic Fe deficiency.     

Plasma lipid profiles and risk of cardiovascular disease on occupational exposure in Karimnagar

Occupational exposure is unregulated in developing countries like India, and becoming the most common cause of disease of environmental origin. The present study was aimed to investigate the effects of occupational exposure on plasma lipid profiles, and risk of cardiovascular diseases. A total of 79 human volunteers were included in the study. Control subjects were healthy housewives of Karimnagar, India. Occupationally exposed individuals included different occupational workers like petrol station attendants, battery chargers, drivers, welders, pesticide-exposed workers, painters, and auto mechanics. These subjects were shown to be chronic occupationally-exposed for at least three years, and neither associated with any other chronic pathological conditions like hypertension or diabetes, nor under any medication other than analgesics during the month preceding the study. Subjects with excessive high or low caloric intake were excluded from the study. Total cholesterol (TC), LDL cholesterol, triglycerides (TG), VLDL cholesterol, LDL/HDL cholesterol, and TC/HDL ratio in these subjects were significantly higher than those in control subjects, whereas HDL cholesterol was not markedly affected. Blood pressure (systolic and diastolic), and other anthropometric parameters (body mass index (BMI), body fat index (BFI), body surface area (BSA)) were not significantly different between groups. Data suggest that chronic occupational exposure increases plasma lipid levels and is thereby associated with cardiovascular complications.     

二叔丁基过氧化物的热失控动力学研究

为研究二叔丁基过氧化物(DTBP)热失控危险性,利用C600微量量热仪对DTBP热分解动力学进行试验研究,测定DTBP在不同升温速率下的起始放热温度和分解热,分别用非等转化率法和等转化率法得到DTBP热分解反应的动力学参数。用非等转化率法确定反应的最佳反应级数为1,相应的活化能分别为137.75、132.60、128.61和122.93 kJ/mol,指前因子分别为8.82×1012、6.69×1012、2.06×1012和3.89×10111/s。用等转化率法确定的活化能范围为102～138 kJ/mol,并拟合出活化能与转化率的关系曲线。结合计算出的动力学参数,通过对DTBP分解机理的分析,可以推断其具有热失控危险性。     

特征参数对单自由度结构随机临界地震响应影响的研究

结构物受地震作用的动力分析法可分为两大类,一类是确定性分析方法,另一类是概率性分析方法。随机临界地震响应分析法作为概率性分析法的一种,是指在地震激励均方值已知的条件下,找出使响应方差最大的临界地震激励。本文针对一单自由度水塔结构,在平稳高斯过程地震动输入下,运用随机地震响应分析法,求解了随机临界地震响应,并分析了控制临界地震激励的平均零穿越率的参数P、结构阻尼比、正交函数系的选择和项数等对体系随机临界地震响应的影响,得到一些有益的结论,对实际工程的运用具有一定的指导价值。