二维解卷积波束形成水下高分辨三维声成像

针对水下三维成像的空间分辨率难以提高,且具有较高旁瓣级的问题,提出了一种二维解卷积波束形成高分辨三维声成像算法,该算法首先完成任意距离切片的平面阵波束形成,近场情况下采用菲涅尔近似实现近场平面阵波束形成,然后通过二维解卷积技术对任意距离切片的二维波束形成结果进行解卷积处理,去除阵列指向性函数的影响,改善波束响应非理想冲击函数所造成波束形成主瓣宽及旁瓣级高的问题。通过计算机仿真分析,新算法可以有效的提高水下三维成像的空间分辨率,抑制旁瓣级,并能够在较宽频带和不同阵列孔径内保持与常规波束形成相当的稳定性。通过试验研究,新方法比常规波束形成实际目标成像分辨率提高一倍,最高旁瓣级下降20 dB,验证了该算法在实际系统中的有效性.     

Se7环两种构型的结构和红外振动光谱的理论研究

在从头算层次上采用自洽场Hartree-Fock(SCF-HF)与密度泛函理论(DFT) 的定域自旋密度泛函SVWN和杂化泛函B3LYP方法以及6-31+G(d)基组,计算优化了Se7环cha ir和boat两种分子构型。以B3LYP/6-31+G(d)优化的结构为基础,计算了Se7环两种构型 的红外振动光谱,标定了这两种构型的各个简谐振动模式的对称性。计算结果与前人的理论 、实验数据进行了比较。     

马面鲀鱼皮复制及润湿性研究

以具有防污功能的马面鲀皮为生物复制模板,采用铸膜方法对其微观形貌进行了大面积复制,并对复制表面的润湿性进行了分析研究。研究结果表明,复制的PDMS样品表面产生了与生物样品一致性较好的绒毛结构。该结构大大增加了表面的疏水性,将使海洋生物附着的难度大幅度增大,从而改善表面的污损释放性能。     

造纸污泥在回转窑中热解的试验研究

本文在自行设计的小型外热式回转窑试验装置上进行了污泥热解试验,考察了污泥在不同热解连温下三种形态热解产物的产率,分析了污泥在热解过程中热解气体的成分和热值的变化特性以及热解半焦的品质。采用表观动力学模型对热解气体的试验数据进行计算,结果表明用该模型描述热解气体的析出是合理的。     

时域压缩合成孔径超分辨水声成像算法

提出一种针对水下稀疏目标的时域压缩合成孔径声呐成像方法(TC-SAS),实现了水声目标高分辨实时成像。通过多子阵的孔径合成,在时域上构造出成像网格格点到有效孔径内逐帧阵列的格林函数,并给出成像区域散射强度到数据域的映射矩阵;然后利用该区域空域稀疏的先验知识,通过正交匹配追踪的稀疏重构方式,解算出成像区域散射系数矩阵,实现了稀疏目标高分辨成像.同时,针对线性调频信号提出数据缩减的方法,通过对观测数据和字典矩阵同时脉压后截取,减小了数据规模;进一步结合二维矩阵数表查表的方法,以空间换时间,实现了区块实时成像。数值仿真以及湖试试验表明,所提算法能分辨出传统的时延求和算法难以分辨的目标,并且在图像清晰度指标上平均提升4.9 dB.改善了合成孔径声呐的成像质量.     

造纸污泥与废水污泥流化床焚烧时NO_x和SO_2的排放特性研究

1前言流化床焚烧污犯是近年来发达国家广泛采用的方法，它能很好地实现污泥的稳定化、无害化、减容化和资源化处理。燃煤流化床锅炉污染物排放方面已做了大量的研究工作，由于污泥与煤在结构和性质方面的差异较大，因此有必要对流化床焚烧污泥时污染物排放特性进行研究。本文详细研究了造纸、废水污泥在流化床中焚烧时污泥水份、运行床温及过量空气对NO。和SO。的排放特性及污泥N－＋NO。、S－SO。的转化率的影响，并对这两种性质差异较大的污泥焚烧时的NO。和502的生成特性进行了对比分析，取得了许多有价值的结果，为污泥流化床焚烧…     

An Edge Server Placement Method Based on Reinforcement Learning

In mobile edge computing systems, the edge server placement problem is mainly tackled as a multi-objective optimization problem and solved with mixed integer programming, heuristic or meta-heuristic algorithms, etc. These methods, however, have profound defect implications such as poor scalability, local optimal solutions, and parameter tuning difficulties. To overcome these defects, we propose a novel edge server placement algorithm based on deep q-network and reinforcement learning, dubbed DQN-ESPA, which can achieve optimal placements without relying on previous placement experience. In DQN-ESPA, the edge server placement problem is modeled as a Markov decision process, which is formalized with the state space, action space and reward function, and it is subsequently solved using a reinforcement learning algorithm. Experimental results using real datasets from Shanghai Telecom show that DQN-ESPA outperforms state-of-the-art algorithms such as simulated annealing placement algorithm (SAPA), Top-K placement algorithm (TKPA), K-Means placement algorithm (KMPA), and random placement algorithm (RPA). In particular, with a comprehensive consideration of access delay and workload balance, DQN-ESPA achieves up to 13.40% and 15.54% better placement performance for 100 and 300 edge servers respectively.     

Enhanced Crude Oil Sorption by Modified Plant Materials in Oilfield Wastewater Treatment

The treatment of oilfield wastewater with high crude oil content and complex composition is a problem requiring considerable attention. In order to effectively remove crude oil contained in wastewater, in this work, rice straw, as an oil-absorbing material, was modified and used as a sorbent for crude oil. Rice straw was modified with alkali and cetyltrimethylammonium chloride (CTAC) by simple substitution reaction. The adsorption capacity of modified rice straw for oil was evaluated. The results illustrate that the adsorption rate of rice straw for crude oil was increased from 0.83 to 8.49 g/g, with the optimal conditions of 18% NaOH reacted for 90 min at 50 °C and 2% CTAC reacted for 60 min at 20 °C. The proposed modification method could be used for different materials to enhance the adsorption rate. The results of the contact angle test show that the modified straw changed from hydrophilic to hydrophobic, which may be the main reason for the improvement in the oil absorption rate. Finally, the surface structure of rice straw was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and N₂ adsorption–desorption isotherms, which further confirmed the hydrophobicity of the modified rice straw.     

青海省海东地区土壤中硒的测定

以原子荧光光谱法（AFS）测定青海省海东富硒地区土壤中硒的含量.方法的回收率在97.9％-99.7％之间,相对标准偏差为1.03％-1.72％之间（n=7）.实验证明,建立的方法简单快速,精密度高,满足对土壤中硒的检测要求.     

以SBA-16为模板电沉积生长多孔氧化铁纳米线阵列

采用电化学沉积法以Mn改性的三维体心立方结构的介孔SBA-16膜为模板制备Fe纳米线.沉积Fe后的SBA-16膜以2%HF溶解SiO₂骨架,样品于550℃焙烧4 h.SEM和TEM的研究结果显示,所制备的Fe₂O₃纳米线互相平行,孔径均匀.XRD、电子衍射及HRTEM研究表明Fe₂O₃纳米线具有(多孔)单晶结构.