具有时滞的利率-流通量方程的建立及其应用

本文对金融网络建立了带有时滞的利率-流通量方程，应用时滞微分方程理论，我们得到金融网络中，各节点利率最终将稳定于其基本利率的充分必要条件；给出了各节点利率均振动的充分必要条件以及存在周期解的充分必要条件。     

旋涡流化床颗粒夹带和扬析的数学模型

本文结合气体湍流运动模型，颗粒运动的轨道模型和密相床层动力学的经验关联式，建立了旋涡流化床颗粒夹带和扬析的数学模型，发展了相应的求解程序。用本文提出的数学模型对普通鼓泡流化床中颗粒夹带的计算结果与前人的经验公式相符；对旋涡流化床和普通的鼓泡流化床颗粒扬析的计算结果与实验数据吻合较好。     

Applications of ultrasound to enhance fluidized bed drying of Ascophyllum Nodosum: Drying kinetics and product quality assessment

In this study, ultrasound either as a pretreatment technique or as an integrated technique was employed to enhance fluidized bed drying of Ascophyllum nodosum, and drying kinetics and dried product quality were assessed. In order to compare technology efficiency and dried product qualities, oven drying and fluidized bed drying (FBD) were employed. The novel drying methods included airborne ultrasound-assisted fluidized bed drying (AUA), ultrasound pre-treatment followed by FBD (USP), and hot water blanching pre-treatment followed byFBD (HWB). Six drying kinetics models were used to describe the drying curves, among which the Page model was the best in fitting USP and AUA. Model by Millidi et al. was employed to describe HWB. Airborne ultrasound in AUA did not reduce energy consumption or drying time, but retained total phenolic content (TPC) as well as colour, and exhibited the highest yield among the novel drying methods. USP and HWB showed lower energy consumption and drying time considerably, but the TPC was the lowest among the studied methods. At the same time, USP dried product exhibited the lowest a_w, followed by HWB and then AUA. This studyalso demonstrated that FBD could be a very practical drying method on Irish brown seaweed, and ultrasound-assisted drying methods may have potential developments in Irish brown seaweed drying process.     

纳米颗粒团聚物流化特性的数值研究

基于气固两相流体动力学理论,建立气体纳米颗粒团聚物两相流动双流体模型.模型中采用了Jung ＆ Gidaspow (2002)测量的固相应力模量和王垚等(2001)提出的聚团曳力系数计算模型.对纳米颗粒团聚物的流化过程进行了数值模拟,得到纳米颗粒团聚物的流化特性.模拟得出的床层膨胀比与文献中实验的结果较为接近.     

Can a Circulating Light Beam Produce a Time Machine

In a recent paper, Mallett found a solution of the Einstein equations in which closed timelike curves (CTC’s) are present in the empty space outside an infinitely long cylinder of light moving in circular paths around an axis. Here we show that, for physically realistic energy densities, the CTC’s occur at distances from the axis greater than the radius of the visible universe by an immense factor. We then show that Mallett’s solution has a curvature singularity on the axis, even in the case where the intensity of the light vanishes. Thus it is not the solution one would get by starting with Minkowski space and establishing a cylinder of light.     

煤的清洁利用技术的现状与发展

文章针对中国一次能源以煤为主的特点,深入分析了几种主要的煤的洁净利用技术的现状及存在的主要问题和发展趋势,其中包括大容量、高参数的超(超)临界燃煤发电技术、燃煤烟气净化技术、循环流化床燃烧技术(CFBC)、整体煤气化联合循环技术(IGCC)和煤的洗选技术.在此基础上,给出了中国煤的清洁利用方式的建议:近期仍以超(超)临界燃煤发电机组+燃煤烟气净化技术和循环流化床燃烧技术为主;整体燃气化联合循环技术、富氧燃烧技术(特别是加压富氧燃烧技术)以及二氧化碳的捕集和封存技术(CCS),具有广阔应用前景,值得长期大力发展.     

福建无烟粉煤催化气化

报导了福建无烟粉煤在碱性催化剂作用下的催化气化工作进展,在小型Φ１８ｍｍ固定床与Φ２０ｍｍ流化床中,进行了水蒸气气化、混合气（空气／水蒸气）气化,采用复合１催化剂添加量８％,８５０～９００℃及流化床条件下,即可获得产气率Ｖ＞３ｍ３／ｋｇ煤（无催化剂时,Ｖ＜１．６ｍ３／ｋｇ煤）及煤气热值ＱＬＶＨ＞９ＭＪ／ｍ３（水蒸气气化）与＞６ＭＪ／ｍ３（混合气气化）的结果,并与无烟煤气化的工业装置进行了比较,这为无烟粉煤有效转化的工业化试验提供了最重要的依据     

准东煤流化床气化飞灰的理化特性研究

采用灰熔点测定仪、X射线荧光光谱仪、扫描电镜和热重分析仪等方法,研究了准东煤流化床气化飞灰的灰熔融特性、物理结构和化学组成及气化反应活性。结果表明,准东煤与其流化床气化飞灰中Si O2、Fe2O3、Na2O和Ca O等矿物质含量存在显著的差异,但飞灰的灰熔点与原煤无明显差异。准东煤气化飞灰具有较宽的粒径范围,呈现双峰分布特征,且不同粒径区间飞灰的元素含量存在显著差异。提高气化温度,有利于提高飞灰的气化反应活性。准东煤流化床气化飞灰石墨化程度比煤焦要高,但其孔隙结构更为发达,含有丰富的中孔和中大孔,使得飞灰的气化反应活性高于煤焦。可通过提高气化温度、循环再气化的方法提高气化效率。     

生物质在流化床中的热解和气化研究

在水蒸气及氮气流态化条件下 ,对不同生物质原料进行了热解气化实验 ,研究气体产物产率、成分随反应温度的变化规律。在一个常压鼓泡流化床实验台上 ,对五种生物质原料热解气化综合过程的气体产物产率及成分进行了测定。文中重点分析了原料SD2 0 1 (EucalyptusGlobulus锯末 )与SD2 0 2 (PinusRadiata锯末 )在水蒸气及氮气流化和不同温度条件下的热解气化特性 ,同时还分析了两种流化介质条件下生物质热解气化实验结果的差别。