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关键词： Hybrid airlift reactor   Three-phase reactor   Dispersion   Mixing time  

摘要： The paper presents the results of experimental investigation of the mixing characteristics of an external-loop hybrid fluidized-bed airlift reactor. Stimulus-response tracer experiments were carried out using KCl solution as a tracer. Based on the obtained tracer residence time distribution (RTD) curves, values of the Peclet number for the entire apparatus and its selected zones i.e. fluidization, bubbling, bottom and degassing zones were determined. The values of Pe were calculated using three different methods, i.e. method of moments, optimization method combined with numerical solution of the axial dispersion model and by fitting the experimental data to a special solution of the axial dispersion model describing the response of the loop apparatus to the impulse of tracer. The mixing time was determined both from the experimental RTDs and through using the proposed theoretically derived expression that permits an estimation of the values of mixing time based on a single liquid circulation. (C) 2019 Elsevier Ltd. All rights reserved.

关键词： Flow classification   switching system   range matching   field programmable gate array (FPGA)   pipeline architecture  

摘要： Network flow classification is a key function in high-speed switches and routers. It directly determines the performance of network devices. With the development of the Internet and various kinds of applications, the flow classification needs to support multi-dimensional fields, large rule sets, and sustain a high throughput. Software-based classification cannot meet the performance requirement as high as 100 Gbps. FPGA-based flow classification methods can achieve a very high throughput. However, the range matching is still challenging. For this, this paper proposes a range supported bit vector (RSBV) method. First, the characteristic of range matching is analyzed, then the rules are pre-encoded and stored in memory. Second, the fields of an input packet header are used as addresses to read the memory, and the result of range matching is derived through pipelined Boolean operations. On this basis, bit vector for any types of fields (AFBV) is further proposed, which supports the flow classification for multidimensional fields efficiently, including exact matching, longest prefix matching, range matching, and arbitrary wildcard matching. The proposed methods are implemented in FPGA platform. Through a two-dimensional pipeline architecture, the AFBV can operate at a high clock frequency and can achieve a processing speed of more than 100 Gbps. Simulation results show that for a rule set of 512-bit width and 1 k rules, the AFBV can achieve a throughput of 520 million packets per second (MPPS). The performance is improved by 44% compared with FSBV and 30% compared with Stride BV. The power consumption is reduced by about 43% compared with TCAM solution.

关键词： Traffic data analysis   clustering   k-means algorithm   Silhouette analysis   Shannon entropy  

摘要： We investigated the speed time series of the vehicles at a section of a highway in the city of Isfahan, Iran. Using k-means clustering algorithm, we find that the natural number of clustering for this set of data is 3. This is in agreement with the three-phase theory of uninterrupted traffic flows. According to this theory, the three traffic phases are categorized as free flow (F), synchronized (S) and wide moving jam (J). We obtain the transition speeds and densities at F-S and also S-J transitions. We also apply the Shannon entropy analysis on the speed time series over finite windows, which equips us to monitor in areal time the instant state of a traffic flow.

关键词： Three-phase inverse fluidized bed   Hydrodynamic characteristics   Flow regimes   Fluidization ratio   Phase holdup  

摘要： A new bubble-induced three-phase inverse fluidized bed (BIFB) is proposed, where particles lighter than water are fluidized downwards by upward flowing gas without net liquid flow due to the reduced net gas-liquid mixture density and the turbulence caused by bubble flow. Key advantages include uniform fluidization of particles, zero or low liquid flowrate, low energy consumption and easy re-fluidization, showing great potential in biochemical, bioprocess, food, environmental and petrochemical industry. In a 0.33 m diameter pilot-scale BIFB column, four flow regimes;initial fluidization gas velocity and complete fluidization gas velocity were identified, using particles of different diameters and densities. A new concept, the fluidization ratio, is devised to best describe the fluidization quality in BIFB. (C) 2019 Published by Elsevier Ltd.

关键词： Sesame stalks   broad bean stalks   biomass chips   bubbling fluidized bed combustion   combustion characteristics   emissions  

摘要： The study work investigated the combustion characteristics and gaseous emissions during burning chips of sesame and broad bean stalks in a pilot-scale Bubbling Fluidized Bed Combustor (BFBC). The effects of the startup temperature, excess air percentage, moisture content, and injection location of secondary air on axial temperature profiles along the combustor and flue gas emissions were studied. The results indicated that biomass fuel characteristics have a significant role in the distribution of axial temperature along the reactor height. A great effect on the axial temperature profile was detected when the startup temperature was changed. The 30% and 100% excess air represent the near percentages for better combustion characteristics for burning the stalks of broad bean and sesame, respectively. Enhancement was observed in the combustion behavior when using the dried samples compared to the as-received samples. Higher values of axial temperature and lower concentrations of flue gas emissions are a result of rising injection location of the secondary air. The combustion efficiency reached to 92.4% for burning the sesame stalks and 96.6% for the broad bean stalks. Based on an energy balance performed on the BFBC, the thermal efficiency was ranged from 28.2% to 59.4% for SS and from 17.2% to 42.1% for broad bean stalks.

关键词： 碳—氧同位素   主—微量元素   碳酸盐胶结物   平台地区   柴达木盆地  

摘要： 综合运用岩石学、矿物学以及元素地球化学等理论,对柴达木盆地北缘构造带中段平台地区古近系路乐河组(E1+2)储集岩的岩石学特征、碳酸盐胶结物、黏土矿物以及沉积成岩环境进行分析研究。结果表明:平台地区路乐河组储集岩主要为岩屑砂岩和长石岩屑砂岩,储集岩内颗粒之间以点—线接触关系为主,少量为线接触关系;孔隙类型以原生粒间孔为主,其次为粒内溶蚀孔隙;黏土矿物含量较高,平均值达到了21.92%,主要以伊—蒙混层、伊利石、蒙脱石和绿泥石为主,具有明显的蒙皂石向伊—蒙混层转化的特征。碳—氧同位素分析结果显示碳同位素值(δ13C)在-8.87‰^-3.91‰之间,平均为-5.66‰,碳来源主要为脱羧作用的有机质碳和碳酸盐岩中的无机碳,淋滤作用也造成胶结物中δ13C值变低;氧同位素值(δ18O)介于-12.97‰^-8.75‰,平均值为10.68‰,推算其古盐度Z值分布范围在103.79~114.27之间,平均为110.38,碳酸盐沉淀温度分布范围在62.89℃~90.53℃之间,平均为75.20℃;通过全岩的微量元素分析表明,U/Th、V/Cr、Ni/Co以及Cu/Zn均反映出温暖、湿润的成岩环境,古盐度、Sr/Ba与U值也指向淡水沉积环境,说明平台地区路乐河组储集岩主要形成于温暖湿润的淡水沉积环境之中。

关键词： 顺北地区   走滑断裂   流体特征   地球化学   储层发育模式  

摘要： 塔里木盆地顺北油田在上奥陶统覆盖区的非暴露条件下,沿走滑断裂发育大量缝洞储集体。通过高精度三维地震和测井资料分析,结合钻井、录井及生产动态数据,研究认为,塔里木盆地顺北地区的储集空间类型主要为沿深大断裂带的断面发育且受溶蚀改造的大型洞穴或断面空腔,其次为断裂破碎带内的砾(粒)间缝、砾(粒)内缝、高角度构造缝以及伴生的溶蚀孔洞。储层受通源主干走滑断裂带控制,横向非均质性强,但纵向连通性好,断裂面是储层发育的有利部位。主干走滑断裂具有明显的分段性,且断裂带内部结构复杂,发育交织的多重断层核部结构,直接影响着储层的展布。通过岩石学和地球化学综合分析认为,储层最主要的改造流体以通源走滑断裂导致的上行深埋成岩-成痉流体为主,局部存在热液流体成岩改造特征。通源走滑断裂贯穿了层序界面、岩性界面以及热液流体运移界面等多套具备储层物质基础的地层,形成了顺北地区纵向连通性强,横向可延展的规模储集体。

关键词： 无阀   压电泵   阻流体   绕流阻力   微混合器  

摘要： 针对生物、化学、医学、航空等领域混合输送微流体、微流体介质的需要,提出了集流体混合、泵送为一体的复合阻流体无阀泵,并借助复合阻流体致涡实现涡致混合功能。基于流体绕流原理对绕流阻力进行了全新诠释和表达;并利用“尾流空间压强比较法”和“流体单元动量分析法”进行了绕流复合阻流体的阻力分析,揭示了复合阻流体致阀及其本质性成因;改变传统无阀泵的结构,通过引入分流环和复合阻流体,减少泵回流量的同时实现了涡致混合的功能。制作了泵样机,在驱动频率为11 Hz、电压为180 V条件下进行了泵流量试验和流体混合试验,其瞬时流量达到53.7 mL/min;同时,借助流体涡的运动较好地混合了流体,试验验证了新型泵具有混合及泵送流体的功能。新型泵的提出创新和丰富了无阀泵的结构和功能,为无阀泵应用于微流体混合传输领域奠定了基础。

关键词： 蜂窝状结构   表面反射   气体压力   肥皂泡   表面张力   表面积  

摘要： 在气体压力和表面张力的共同作用下,肥皂泡要在体积不变的前提下努力使表面积最小,故而大部分时候呈球形。而当多个肥皂泡挤在一起时,就会形成不规则的蜂窝状结构。从肥皂泡薄膜上下表面反射回来的阳光会发生干涉,让有些颜色的光减弱,有些颜色的光增强,所以我们看到的肥皂泡是彩色的。