改进BP神经网络在木构古建筑中的寿命预测

标准的BP神经网络存在训练速度慢、容易陷入极小点、泛化能力低的特点。文中用附加动量项和改进学习速率相结合的方法对标准的BP神经网络进行了改进,并将其应用在木构古建筑的寿命预测中。仿真结果表明,和标准的BP神经网络相比,改进后的BP神经网络提高了泛化能力,能较准确地拟合训练值,避免了在确定计算参数过程中所产生的计算误差。     

江淮丘陵区塘坝灌溉能力估算及其演变特征

鉴于塘坝工程在江淮丘陵区蓄水灌溉中的重要作用,通过对塘坝工程与作物种植结构发展历程的综合分析,提出了基于水量供需平衡分析的塘坝灌区灌溉能力概念及其计算模型,定量评估了江淮丘陵区不同年代的塘坝灌溉能力,揭示了塘坝灌溉能力的动态演变特征。研究结果表明:江淮丘陵区全区塘坝灌溉能力在20世纪60年代达到峰值后,70～90年代呈显著下降趋势,至21世纪初有所回升。研究结果可为江淮丘陵区塘坝发展规划与灌溉制度的制定提供理论依据与技术支撑,具有重要实际指导意义。     

一种防篡改且可恢复流指纹编码方案

针对流交换中网络抖动和流变换导致的流指纹不可用、不可信问题,提出了一种防篡改且可恢复的流指纹编码方案。通过提出流特征信息作为自适应参数,以此作为超混沌系统的初值,构造双重指纹。与此同时,利用门限理论,以提高流指纹信息的防篡改能力和流指纹的自恢复能力。通过增加密钥空间以加大攻击难度、降低检测计算复杂度以提高检测效率。同时,为了实现流指纹的自恢复能力,将流指纹分为相互关联的两重子指纹信息,并对每一重子指纹再次进行分散。此外,对该方案的防篡改性和可自恢复能力进行了理论分析。最后,实验说明了该方案的高正确率和良好实用性.     

3000m起重铺管船铺管作业率研究

针对3 000 m起重铺管船的运动性能,对其铺管作业率做了相应的研究。将模型试验得出的规则波运动响应的每个自由度的n个数据点通过样条差值的方法编写到不规则波响应谱中,并采用变步长勒让德-高斯积分的方法求解出船舶不规则波运行的单幅最大值。同时,与SESAM程序软件的计算结果作对比,经研究,验证了该计算方法的有效性。最后,将计算出的一系列单幅最大值与相应校准值作比较,根据海况资料,将所有满足条件的一系列不规则波的发生概率相加,则起重铺管船在特定工况下的铺管作业率得到了求解。     

Leaching Stability of Simulated Waste Forms for Immobilizing An3＋ by Gd2Zr2O7 with Nd3＋

In order to investigate the anti-leaching capability of pyrochlore Gd2Zr2O7 immobilized An3+, trivalent neodymium was used as the simulacrums for radioactive wastes with trivalence, Gd2-xNdxZr2O7(0.0x 2.0) series samples were successfully synthesized by high temperature solid reaction and using Gd2O3, Zr O2 powders as starting materials. The experiments of long-term chemical stability were conducted in synthetic seawater at 40 and 70 ℃. The XRD diffractive data and extraction ratio of as-received samples were collected with the help of X-ray diffraction(XRD) instrument and inductively coupled plasma mass spectrometry(ICPMass). The results indicate that the phases of as-received compounds keep the single phase of pyrochlore. The extraction ratio of Gd3+, Zr4+ and Nd3+ in waste forms is increasing with the increase of immersion time in synthetic seawater. The extraction ratio of waste forms at 70 ℃ is higher than at 40 ℃. The highest extraction ratio of Gd3+, Zr4+ and Nd3+ after 42 days is near 0.025 8, 0.003 8 and 0.045 2 μg·m L-1, respectively.     

知识管理能力、创业导向与中小企业绩效的关系研究

首先通过知网搜索相关文献,讨论知识管理能力、创业导向与企业绩效的基本内涵;其次挖掘三者之间可能的潜在关系,提出了创业导向、知识管理能力与企业绩效之间关系的基本假设、理论雏形以及相关变量测度问题,在此基础上,收集皖江城市带中小企业相关数据进行实证分析。实证结果表明:创业导向、知识管理能力对企业绩效起着正向作用;创业导向对知识管理能力起着正向作用;知识管理能力在创业导向对企业绩效中起着部分中介作用。最后,提出结论、相关建议以及未来展望。     

High-rate capability of spinel LiNi0.05Mn1.95O4 cathode for Li-ion batteries prepared via coprecipitated precursor

Spinel LiNi0.05Mn1.95O4 cathode material for lithium ion batteries was synthesized by solid-state reaction from coprecipitated Ni-Mn hydroxide precursors and characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM） and galvanostatic charge-discharge tests. It is found that LiNi0.05Mn1.95O4 powder has an ordered cubic spinel phase （space group Fd3m） and exhibits superior rate capability. After 450 cycles, the LiNi0.05Mn1.95O4/carbonaceous mesophase spheres（CMS） Li-ion batteries can retain 96.0% and 93.3% capacity at 5C and 10C charge/discharge rate, respectively, compared with 85.3% （5C） and 80.5% （10C） retention for LiMn204 batteries. However, the initial discharge capacity of LiNi0.05Mn1.95O4/CMS batteries at 1C charge/discharge rate （96.20 mA.h/g） is slightly lower than that of the LiMn2O4 batteries （100.98 mA.h/g） due to the increased average oxidation state of Mn inLiNi0.05Mn1.95O4.     

Charge-discharge process of MnO2 supercapacitor

Mechanochemical synthesis of α-MnO2 was carried out with KMnO4 and Mn（CH3COO）2 in 1：1 mole ratio. The electrochemical performance of MnO2 electrode was investigated by cyclic voltammograms and alternating current impedance. The charge-discharge process of MnO2 supercapacitor in 6 mol/L KOH was studied within 1.2 V at 200 mA/g, suggesting that it displays double-layer capacibility in low potential scope and pseudo-capacitance properties in high potential scope. It is found that Mn3O4, an electrochemical inert, mainly forms in the initial 40 charge-discharge cycles. During cycling, the pseudo-capacitance properties disappear and the discharge curves are close to ideal ones, indicating double-layer capability. The maximum capacitance of MnO2 electrode is as high as 416 F/g, and retains 240 F/g after 200 cycles. The equivalent series resistance increases from 17 to 41Ω.     

Effects of NH4F on the deposition rate and buffering capability of electroless Ni-P plating solution

The deposition rate and buffering capability of alkaline electroless Ni-P plating solution containing ammonium fluoride (NH₄F) have been investigated. When the NH₄F concentration is below 10 g L^− 1, the deposition rate is improved with the addition of NH₄F, reaching the maximum value at 2 g L^− 1. The buffering capability of solutions is found to be improved with increasing NH₄F concentration. Due to the improvement of buffering capability, refined and compact Ni-P coatings with homogeneous elemental distribution of P have been achieved. Therefore, both the corrosion resistance and microhardness of Ni-P coatings are significantly improved. The mechanism of NH₄F improving the deposition rate and the buffering capability is discussed.     

基于熵权理论和渴求函数法的多响应优化设计研究

文章首先对多响应优化问题进行了回顾和分析,针对多响应优化设计中权重确定和优化模型的建立问题,探讨了熵权理论和基于过程能力指数的渴求函数法在多响应优化设计中应用的可能性,并提出了熵权理论和渴求函数法结合的多响应优化设计方法,然后通过实例对文中所提的方法进行了实证研究,最后得出结论通过将熵权理论和渴求函数结合应用于多响应优化问题中,可以达到很好的效果。