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Search Results: 1 - 10 of 40763 matches for " ZHENG An-qing "
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 An-Qing Xing International Journal of Stochastic Analysis , 1991, DOI: 10.1155/s1048953391000138 Abstract: This paper is concerned with the generalization, numerical implementation and testing of the non-parameter penalty function algorithm which was initially developed for solving n-dimensional optimization problems. It uses this method to transform a constrained optimal control problem into a sequence of unconstrained optimal control problems. It is shown that the solutions to the original constrained problem. Convergence results are proved both theoretically and numerically.
 An-qing Xing International Journal of Stochastic Analysis , 1989, DOI: 10.1155/s1048953389000201 Abstract: This paper uses the penalty function method to solve constrained optimal control problems. Under suitable assumptions, we can solve a constrained optimal control problem by solving a sequence of unconstrained optimal control problems. In turn, the constrained solution to the main problem can be obtained as the limit of the solutions of the sequence. In using the penalty function method to solve constrained optimal control problems, it is usually assumed that each of the modified unconstrained optimal control problems has at least one solution. Here we establish an existence theorem for those problems. Two numerical examples are presented to demonstrate the findings.
 土壤 , 2011, Abstract: 从土壤墒情监测和指导田间变量灌溉的要求出发,本设计应用单片机控制相应的电器元件对土壤水分进行测量,并结合手机模块通过GSM网络以短信息的方式向外部发送,让管理者实时有效地了解土壤的水分情况,进而控制其他的灌溉设备,及时做好灌溉工作。GSM短信无线通讯技术在无线(手机)通讯领域已相当成熟,把这项技术移植到大范围土壤含水量监测方面是可行的。
 燃料化学学报 , 2012, Abstract: A storage stability test was conducted on the bio-oil produced by fast pyrolysis of pine and corncob.The viscosity,water content and solids content of bio-oil increased after storage.However,there were no significant changes in the pH value,heating value and density of bio-oil.The quantitative analysis by GC/MS showed that the content of 1-hydroxy-2-propanone,acetic acid,and furfural were significant decreased.The content of 2-methoxy phenol,4-methyl-2-methoxy-phenol,and 4-methyl-phenol increased.13C NMR spectral analysis showed that the alkyl carbon and di-O-alkyl carbon content of bio-oil decreased after storage,while the content of aromatic and unsaturated carbon increased.Therefore,the aromaticity of bio-oil increased.
 燃料化学学报 , 2012, Abstract: Hemicellulose can produce more acid content than cellulose and lignin via pyrolysis.This work reduced the hemicellulose and water content of pine via low temperature pretreatment to improve the bio-oil quality.The chemical composition and FT-IR analysis of pine after pretreatment show that the lignin content increases and the carbonization of pine takes place,which results in the decrease of bio-oil yield and the increase in yield of char and no-condensed gas.With increasing pretreatment temperature,the important characteristics of the bio-oil,such as water content,high heating value,kinematic viscosity,and density all increase,and solid particles content decreases,while pH value decreases after an initial increase.The 13C nuclear magnetic resonance(NMR) show that the aliphatic carbon of bio-oil decreases,while the aromatic and the aromaticity increases.
 资源科学 , 2001, Abstract: With development of economy, the factors that affect urban land vary c onstantly. Urban land gradation and land price evaluation must be renewed in tim e. In the case of Linzhang County, because the rural market and bazzar have been expanded, the original land gradation and land price may be lower. Therefore, i t is necessary to renew the urban land gradation and land price evaluation. Acco rding to the purpose and the principle of land gradation and land price evaluati on, this paper adopts the method of comparing some areas with objective gradatio n to evaluate land gradation. According to the various factors that affect land price, it can adjust the price of land partially or throughout the study area. T his indicates that the method is either practical or operative, and can be appli ed extensively and provide reasonable theory for land gradation and land price e valuation.
 - , 2015, DOI: https://doi.org/10.1007/s12613-015-1055-5 Abstract: The corrosion behavior of expandable tubular materials was investigated in simulated downhole formation water environments using a series of electrochemical techniques. The corrosion morphologies in the real downhole environment after three months of application were also observed by stereology microscopy and scanning electron microscopy (SEM). The results show that, compared with the unexpanded sample, the area of ferrite increases dramatically after a 7.09% expansion. The expanded material shows a higher corrosion current in the polarization curve and a lower corrosion resistance in the electrochemical impedance spectroscopy (EIS) plot at every studied temperature. The determined critical pitting temperatures (CPT) before and after expansion are 87.5°C and 79.2°C, respectively. SEM observations demonstrate stress corrosion cracks, and CO2 corrosion and H2S corrosion also occur in the downhole environment. Due to additional defects generated during the plastic deformation, the corrosion performance of the expanded tubing deteriorates.
 腐蚀科学与防护技术 , 2007, Abstract: 采用自制的腐蚀监测探头,利用交流阻抗技术监测了碳钢在我国青岛海洋大气中的腐蚀行为,腐蚀监测探头是由环氧树脂密封的两个相同大小的长方形碳钢片组成,监测了腐蚀探头溶液电阻(Rs)、极化电阻(Rp)等参数,利用Stern-Geary公式由Rp计算了钢材的腐蚀速度,研究了腐蚀速度与温度、相对湿度的关系.结果表明:温度和相对湿度是影响钢材大气腐蚀的重要因素之一;相对湿度越大,碳钢的腐蚀速度越大;当相对湿度低于碳钢的临界相对湿度时,温度对腐蚀速度几乎没有影响,如果高于其临界相对湿度时,温度升高,腐蚀速度加快;从监测的Rp值变化情况可以看出大气腐蚀是一个非常复杂和不稳定的过程.
 计算机科学 , 2013, Abstract: 通过竖直直方投影和均匀网格离散将激光雷达扫描得到的输电线路三维点云降维成二维灰度图像,提取其中直方响应最大的地方作为杆塔的水平位置,分离杆塔,输电线在走向上以杆塔为界分段；再沿其悬垂面的法线方向对各段输电线作正投影,对投影的散点进行迭代的鲁棒二次曲线拟合,实现在竖直方向上的各层输电线的分离。杆塔的提取和输电线的拟合是实现电力系统净空排查分析、输电线点云实体化和场景漫游的重要环节。
 - , 2017, DOI: 10.3969/j.issn.1674-8115.2017.03.013 Abstract: 目的 ·评价RPR技术治疗复杂肥厚型梗阻性心肌病（HOCM）的临床疗效。方法 · 2009年6月至2015年12月，采用RPR技术治疗复杂HOCM 9例。其中男性6例，女性3例；年龄22～63岁，平均（43±19）岁。术前经胸超声心动图（TTE）均可见二尖瓣收缩期前向运动（SAM），伴有中度或中度以上的二尖瓣反流（MR）。术中经食管超声心动图（TEE）评估手术效果，术后1周内及随访时TTE复查手术效果。结果 · 9例患者均治愈出院。术中TEE证实RPR术后左心室流出道压差（LVOTPG）为（9±3）mmHg，显著低于RPR术操作前[（92±14）mmHg]（P<0.01），SAM征全部消失。术后1周内TTE显示室间隔厚度、LVOTPG、MR明显好转（P<0.01）。术后平均随访26个月，所有患者症状明显减轻，LVOTPG仍处于较低水平，无明显MR，无死亡，无再次手术及其他并发症。结论 · RPR技术可有效解除复杂HOCM的左心室流出道梗阻及MR，提高患者生活质量。： Objective · To evaluate the surgical outcome of RPR composite technique for complex hypertrophic obstructive cardiomyopathy (HOCM). Methods · From June 2009 to December 2015, 9 complex HOCM patients received RPR procedure. There were 6 males and 3 females with age from 22 to 63 years old and the average age of (43±19) years old. Transthorax echocardiography (TTE) showed systolic anterior motion (SAM) and at least moderate mitral valve regurgitation (MR) in all patients before operations. Transesophageal echocardiography (TEE) was used to evaluate the results of procedures during operation. All the patients had been followed up since one week after operation and examined by TTE. Results · All the patients were discharged without complications. Intraoperative TEE indicated that left ventricular outflow tract pressure gradient (LVOTPG) significantly decreased from (92±14) mmHg before operation to (9±3) mmHg after operation (P<0.01). SAM in all the patients disappeared. One week after operation, TTE demonstrated remarkable reduction in the thickness of ventricular septum, LVOTPG and MR than those before operation (P<0.01). Mean follow-up was 26 months. All the patients became asymptomatic. LVOTPG remained low and MR remained mild. There were no deaths, reoperations, or any other adverse consequences. Conclusion · RPR technique is an effective surgical method to relieve LVOTO and MR of complex HOCM to lead a better life
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