基于偏最小二乘法的两栖突击车液压马达故障诊断

液压马达是两栖突击车液压系统中故障发生率较高的元件之一,当马达泄漏量达到允许的极限值时,就要进行更换或者大修.通过分析影响两栖突击车液压马达泄漏量的影响因素,建立了马达泄漏量的偏最小二乘回归模型,得到马达泄漏量的拟合值与测量值的最大相对误差为8%,并预测超过马达允许的泄漏量极限值的时间为9 109 h,为科学确定液压马达的更换期或大修期提供依据.     

Discrete system identification and self-tuning control of dissolved oxygen concentration in a stirred reactor

This work presents the applications of discrete-time system identification and generalized minimum variance (GMV) control of dissolved oxygen (DO) level in a batch bioreactor in which Saccharomyces cerevisiae is produced at aerobic condition. Air flow rate and mixing rate were varied to determine the maximum local liquid phase volumetric mass transfer coefficient (K _L a). Maximum K _L a value was determined at a mixing rate of 600 rpm and air flow rate of 3.4 Lmin⁻¹. For control purpose, manipulated variable was selected as air flow rate due to its effectiveness on the K _L a. To examine the dynamic behavior of the bioreactor, various input signals were utilized as a forcing function and three different model orders were tested. A second0order controlled auto regressive moving average (CARMA) model was used as the process model in the control algorithm and in the system identification step. It is concluded that the ternary input is more suitable than the other input types used in this work for system identification. Recursive least squares method (RLS) was used to determine the model parameters. GMV control results were compared with the traditional PID control results by using performance criteria of IAE and ITAE for different types of DO set point trajectories. DO concentration in the batch bioreactor was controlled more successfully with an adaptive controller structure of GMV than the PID controller with fixed parameters.     

Organelle-targeted nanocarriers: specific delivery of liposomal ceramide to mitochondria enhances its cytotoxicity in vitro and in vivo

To further increase the therapeutic activity of drugs known to act on intracellular target sites, in vivo drug delivery approaches must actively mediate the specific delivery of drug molecules to the subcellular site of action. We show here that surface modification of nanocarriers with mitochondriotropic triphenylphosphonium cations facilitates the efficient subcellular delivery of a model drug to mitochondria of mammalian cells and improves its activity in vitro and in vivo.     

Interaction between photovoltaic distributed generation and electricity networks

Electricity power systems worldwide have traditionally been designed to a vertically connected scheme characterised by centralised generation. Over the last few decades, several factors have dictated a gradual shift from the central‐control approach to a more distributed layout where distributed generation (DG) technologies are effectively integrated and not just connected (appended) to the networks; amongst others liberalisation of electricity markets, security and quality of supply and environmental issues. Photovoltaic powered distributed generation (PV‐DG), although still having a much lesser impact than other DG technologies, is increasingly being embedded into electricity distribution networks worldwide within the framework of successful regulatory state and marketing programmes. PV‐DG has added values (benefits) for the electricity systems that extend from peak power and load reduction (when deployed close to electricity consumption points) to participation in grid‐supporting or grid‐forming modes of operation. The question arises as to what the present situation of PV technology is for its optimal integration in distribution networks, whether there are still technical barriers to overcome as well as new opportunities for PV in future renewably supplied electricity systems. This paper presents the current state of knowledge concerning these topics from a European perspective with regard to different grid structures. It also discusses existing standards, new opportunities to provide grid services and research and development needs identified to fully exploit the added‐value—and still developing—benefits of PV‐DG. Copyright © 2008 John Wiley & Sons, Ltd.     

Optimization of the extraction and purification of oligosaccharides from defatted soybean meal

Summary Optimization of the extraction of oligosaccharides from defatted soybean meal (DSM) was investigated under various conditions. The optimal ratio of water to DSM and optimal temperature for oligosaccharide extraction was 5:1 and 50 °C, respectively. The use of a stirring process, without any further grinding, improved the extractability of oligosaccharides from DSM, a 10% ethanol‐water solution was more effective than distilled water alone. To purify the oligosaccharides, ultrafiltration was used. More than 90% of the protein was removed from the extracts at a volume concentration ratio (VCR) of 3–5. The percentages of fructose, sucrose, raffinose and stachyose in permeate for a VCR of 5 were 38.6, 51.4, 54.2 and 52.6%, respectively. A VCR of 5 was the most effective for protein removal and recovery of oligosaccharides.     

中温大曲发酵过程中细菌群落结构解析及功能预测

利用高通量测序技术解析了中温大曲发酵过程中的细菌群落结构、功能及表型变化。结果表明:中温大曲细菌群落主要由魏斯氏菌属、葡萄球菌属、埃希氏菌属、乳杆菌属等组成;基于OTU水平可将中温大曲样品聚类为前期(0 d和3 d)、中期(9 d和13 d)和后期(30 d)3类;发酵前期以葡萄球菌属为主要优势菌,中期以魏斯氏菌属为主要优势菌,后期则以Muribaculum为主要优势菌;中温大曲细菌菌群的氨基酸转运和代谢、碳水化合物转运和代谢等基因功能丰度较高;与发酵中期相比,发酵前期和后期细菌菌群的细胞壁/膜/包膜生物发生、翻译后修饰、蛋白质折叠和伴侣蛋白等基因功能丰度较高;发酵前期大多为兼性厌氧菌,中期以好氧菌为主,后期则主要是厌氧菌。     

综采工作面瞬时涌出灾害气体弥散规律试验研究

为研究综采工作面灾害气体的运移弥散规律,分析灾害气体运移过程中峰值体积分数及分布的影响因素,在综采工作面内开展示踪气体(SF₆)现场试验,应用一维对流—弥散模型定量分析示踪气体运移特征,使用粒子群算法(PSO)对数学模型中的巷道平均风速和纵向弥散系数进行最优参数估计。结果表明：综采工作面监测到的示踪气体呈现偏态分布,随着运移距离的增加,示踪气体分布影响区域增大;影响监测点处的示踪气体浓度曲线峰值和波形的主要因素是平均风速,其次是纵向弥散系数。对比模拟与试验测试值可以看出,使用一维对流—弥散模型可以准确描述灾害气体在综采工作面内的弥散运移规律。     

陶融型白酒正常和退化窖泥细菌群落多样性解析及其理化影响因素

利用高通量测序技术解析陶融型白酒正常窖池和退化窖池窖泥细菌群落多样性及其在窖池中的空间异质性,并通过冗余分析（RDA）影响微生物群落的主要理化因素。结果表明,退化窖池窖泥的含水量（36.78%）、pH值（5.50）及铵态氮含量（23.48 mg/100 g）均低于正常窖池窖泥,而总酸含量（13.00 mg/g）和有效磷含量（27.32 mg/100 g）与之相反。窖泥中细菌群落存在明显的空间异质性。与正常窖池窖泥相比,退化窖池窖泥中主要优势细菌门厚壁菌门（Firmicutes）（64.32%）、拟杆菌门（Bacteroidetes）（12.58%）以及主要优势细菌属己酸菌属（Caproiciproducens）（3.03%）、嗜蛋白菌属（Proteiniphilum）（6.60%）、棒状杆菌属（Caldicoprobacter）（1.06%）的平均相对丰度较低。有效磷、总酸和铵态氮含量可能是影响不同质量窖泥细菌菌群空间分布的主要理化因子。