Insight into the dissociation mechanism of ethanol molecule over the nano-aluminum surface: a density functional theory study

Journal of Materials Science - Nano-Al-ethanol-based nanofluid fuel as a high-energy fuel has broad application prospects in the field of aviation vehicles. However, the detailed reaction mechanism...     

基于主题序列模式的旅游产品推荐引擎

旅游产品推荐是当前推荐系统研究领域中的新兴议题之一.由于旅游产品描述信息维度多样复杂、“用户-产品”关联矩阵极为稀疏且冷启动问题突出,已经在电子商务领域获得成功的协同过滤推荐往往难以直接被应用于旅游产品推荐.提出基于主题序列模式的旅游产品推荐引擎SECT,试图通过在线旅游网站点击日志的挖掘产生推荐.首先,从页面语义描述文本中挖掘主题,以在泛化层面捕捉用户行为模式;其次,从页面访问时间序列数据中挖掘频繁序列模式及其候选产品集,形成序列模式库;最后,提出Markov n-gram模型,完成用户实时点击流与模式库匹配计算.为了提升在线匹配计算的效率,设计一种新的多叉树数据结构PSC-tree用于存储历史模式库,并与在线计算模块无缝衔接.在真实旅游数据集上的实验结果表明：该推荐引擎比传统推荐算法具有更优越的性能,而且能有效提升冷启动用户的推荐率和准确率.此外,针对长尾物品的推荐,SECT也优于基准算法.     

间谐波检测的FFT算法改进和DSP实现

提出一种快速傅里叶变换(FFT)的改进算法,该算法利用FFT的衰减特性,只需要对FFT算法做简单的变换,就可以有效地消除频谱泄漏分量,实现非整数次谐波的精确检测,克服了传统FFT的缺陷.该算法与加窗体FFT相比,具有相近的特性,在算法构造方面又比加窗体FFT算法更简单,因此该算法更加适合应用于存储资源有限的微处理器上.为证明该算法应用于微处理器的方便性,设计了一套基于数字信号处理(DSP)的谐波检测装置,并对该算法进行了验证.     

多特征信息融合LSTM-RNN检测OSA方法

阻塞性睡眠呼吸暂停(obstructive sleep apnea, OSA)是最常见的睡眠呼吸疾病,它对人体的很多生理系统尤其对心血管系统是一个潜在的威胁.现有使用心电信号(electrocardiograph, ECG)提取浅层特征检测OSA的方法在长片段、高噪声的ECG信号和大数据集上表现较差.针对上述问题,提出一种多特征心电信号融合的长短期记忆循环神经网络,融合从ECG信号中提取的多种浅层特征信号,通过在融合信号上学习深层特征来检测OSA,提升模型在长片段ECG上的检测准确率和大数据集上的泛化能力.同时还针对浅层特征信号提出一种有效的数据预处理方法,用以突出OSA的时序变化,提高神经网络训练的收敛性,并降低由异常值噪声带来的影响,进一步提升模型在高噪声ECG片段上的检测准确率.实验证明：提出的方法在片段OSA检测准确率上优于已有的方法.     

完善新区共用水系统实现零排放

针对公司新区共用水处理系统存在的问题,结合新区共用水处理系统的用户应用方式,研究出解决问题方案,达到减少新水的索取,实现零排放.     

Growth of GaN Thin Films Using Plasma Enhanced Atomic Layer Deposition: Effect of Ammonia-Containing Plasma Power on Residual Oxygen Capture

In recent years, the application of (In, Al, Ga)N materials in photovoltaic devices has attracted much attention. Like InGaN, it is a direct band gap material with high absorption at the band edge, suitable for high efficiency photovoltaic devices. Nonetheless, it is important to deposit high-quality GaN material as a foundation. Plasma-enhanced atomic layer deposition (PEALD) combines the advantages of the ALD process with the use of plasma and is often used to deposit thin films with different needs. However, residual oxygen during growth has always been an unavoidable issue affecting the quality of the resulting film, especially in growing gallium nitride (GaN) films. In this study, the NH₃-containing plasma was used to capture the oxygen absorbed on the growing surface to improve the quality of GaN films. By diagnosing the plasma, NH₂, NH, and H radicals controlled by the plasma power has a strong influence not only on the oxygen content in growing GaN films but also on the growth rate, crystallinity, and surface roughness. The NH and NH₂ radicals contribute to the growth of GaN films while the H radicals selectively dissociate Ga-OH bonds on the film surface and etch the grown films. At high plasma power, the GaN film with the lowest Ga-O bond ratio has a saturated growth rate, a better crystallinity, a rougher surface, and a lower bandgap. In addition, the deposition mechanism of GaN thin films prepared with a trimethylgallium metal source and NH₃/Ar plasma PEALD involving oxygen participation or not is also discussed in the study.     

A Dietary Oxysterol, 7-Ketocholesterol,Exacerbates Imiquimod-Induced Psoriasis-like Dermatitis in Steatohepatitic Mice

Patients with psoriasis are at a higher risk of developing nonalcoholic fatty liver disease. We previously identified an oxidized derivative of cholesterol, 7-ketocholesterol (7KC), in diet-induced steatohepatitic mice. Here, we investigated whether 7KC exacerbates psoriasis-like dermatitis by accelerating steatohepatitis in mice. A high-fat/high-cholesterol/high-sucrose/bile salt diet (nonalcoholic steatohepatitis (NASH) diet) with or without 0.0125% 7KC was fed to C57BL/6 mice (7KC or control group) for three weeks to induce steatohepatitis. A 5% imiquimod cream was then applied to the ears and dorsal skin for four days to induce psoriasis-like dermatitis. Hepatic lipid accumulation and inflammatory cell infiltration were exacerbated in the 7KC group compared with the control group after three weeks. Serum tumor necrosis factor-α (TNF-α) levels were also elevated in the 7KC group (108.5 ± 9.8 vs. 83.1 ± 13.1 pg/mL, p < 0.005). Imiquimod cream increased the psoriasis area severity index (PASI) score in mice in the 7KC group (9.14 ± 0.75 vs. 5.17 ± 1.17, p < 0.0001). Additionally, Tnfa, Il23a, Il17a, and Il22 mRNA levels in the dorsal lesion were significantly upregulated. Finally, Th17 cell differentiation and the TNF signaling pathway were enhanced in the dorsal lesions and liver of mice in the 7KC group. These data suggest that steatohepatitis and psoriasis are linked by a potent, diet-related factor.     

地下室基坑围护方案设计与施工

某工程地下室底板位置土方开挖深度为3.48～3.58m,局部承台、基础梁加深1.10、0.60m不等.土方开挖深度较大,应采取必要的围护措施.根据地质资料,本工程场地内地形较平坦,地表为填土、农田、荒地等.     

一种图像主题网络爬虫的实现方法研究

针对一种图像主题爬虫进行了设计研究,采用了基于文字内容的启发式方法,实现了借助图像文件的锚文本及其上下文进行主题相关性判定,能更准确的抓取相关图像资源.还对网页实现了主题相关性判定,以便更有效地引导爬虫的爬行路经.经实验证明,本系统可起到一定的优化效果,为实现定向主题的图像信息采集奠定了良好的基础.     

Design of cavern blasting based on controllable parameters

After a thorough review of some controllable parameters, which included field investigations, cavern dimensions, explosive, rock strength etc., cut, contour, lifters and stoping holes were introduced for blasting cavern of nucleus submarine. These design were conducted using a U. Langefors and B. Kihlstrom theory. Supported by the Navy Cavern Project Foundation of China (02)