Experimental study on secondary air mixing along the bed height in a circulating fluidized bed with a multitracer-gas method

A multitracer-gas method was proposed to study the secondary air(SA)mixing along the bed height in a circulating fluidized bed(CFB)using carbon monoxide(CO),oxygen(O_(2)),and carbon dioxide(CO_(2))as tracer gases.Experiments were carried out on a cold CFB test rig with a cross-section of 0.42 m×0.73 m and a height of 5.50 m.The effects of superficial velocity,SA ratio,bed inventory,and particle diameter on the SA mixing were investigated.The results indicate that there are some differences in the measurement results obtained using different tracer gases,wherein the deviation between CO and CO_(2) ranges from 42%to 66%and that between O_(2) and CO_(2) ranges from 45%to 71%in the lower part of the fluidized bed.However,these differences became less pronounced as the bed height increased.Besides,the high solid concentration and fine particle diameter in the CFB may weaken the difference.The measurement results of different tracer gases show the same trends under the variation of operating parameters.Increasing superficial velocity and SA ratio and decreasing particle diameter result in better mixing of the SA.The effect of bed inventory on SA mixing is not monotonic.

Particle residence time distribution and axial dispersion coefficient in a pressurized circulating fluidized bed by using multiphase particle-in-cell simulation

The particle residence time distribution(RTD)and axial dispersion coefficient are key parameters for the design and operation of a pressurized circulating fluidized bed(PCFB).In this study,the effects of pressure(0.1-0.6 MPa),fluidizing gas velocity(2-7 m·s^(-1)),and solid circulation rate(10-90 kg·m^(-2)·s^(-1))on particle RTD and axial dispersion coefficient in a PCFB are numerically investigated based on the multiphase particle-in-cell(MP-PIC)method.The details of the gas-solid flow behaviors of PCFB are revealed.Based on the gas-solid flow pattern,the particles tend to move more orderly under elevated pressures.With an increase in either fluidizing gas velocity or solid circulation rate,the mean residence time of particles decreases while the axial dispersion coefficient increases.With an increase in pressure,the core-annulus flow is strengthened,which leads to a wider shape of the particle RTD curve and a larger mean particle residence time.The back-mixing of particles increases with increasing pressure,resulting in an increase in the axial dispersion coefficient.

Circulating tumor cells in lung cancer:Detection methods and clinical impact

Circulating tumor cells(CTCs) are tumor cells that enter the blood circulation after detaching from the primary tumor and can migrate to reach distant organs, where they can give rise to aggressive metastasis. Clinical studies have revealed that the presence of CTCs in peripheral blood is correlated with disease progression in lung cancer. However, as CTCs are rare cancer cells released from tumors into the bloodstream, both enrichment and sensitive detection methods are technically challenging. In order to best understand how CTCs are currently being deployed, this review mainly focuses on the different detection methods for CTCs. Furthermore, we will describe the clinical impact of circulating tumor cells in lung cancer and discuss their potential use as biomarker to guide the prognosis.

Dynamic Modeling of Key Operating Parameters for Supercritical Circulating Fluidized Bed Units based on Data-Knowledge-Driven Method

To address the pressing need for intelligent and efficient control of circulating fluidized bed(CFB)units,it is crucial to develop a dynamic model for the key operating parameters of supercritical circulating fluidized bed(SCFB)units.Therefore,data-knowledge-driven dynamic model of bed temperature,load,and main steam pressure of the SCFB unit has been proposed.Firstly,a knowledge-driven method is employed to develop a dynamic model for key operating parameters of SCFB units.The model parameters are determined based on the operating data of the unit and continuously optimized in real time.Then,Bidirectional Long Short-Term Memory combined with Convolutional Neural Network and Attention Mechanism is utilized to build the dynamic model of bed temperature,load,and main steam pressure.Finally,a collaboration and integration method based on the critic weight method and the variation coefficient method is proposed to establish data-knowledge-driven model of key operating parameters for SCFB units.The model displays great accuracy and fitting ability compared with other methods and effectively captures the dynamic characteristics,which can provide a research basis for the design of intelligent flexible control mode of SCFB unit.

Simulation of the L-valve in the circulating fluidized bed with a coarse-grained discrete particle method

Stable and controllable solid flow is essential in circulating fluidized bed (CFB) systems. The L-valve is a typical non-mechanical valve that can provide flexible solid feeding. The investigation of the solid circulation rate and the hydrodynamic characteristics of the L-valve is crucial to its design and operation. The gas-solid flow in the L-valve of a full-loop CFB is studied with the coarse-grained discrete particle method (EMMS-DPM). Good agreements on the solid circulation rate and the pressure drop through the L-valve are achieved between the simulated and experimental data. The solid circulation rate increases linearly with the aeration velocity until the stable particle circulation of the CFB is destroyed. The flow patterns in the horizontal section of L-valve are gas-solid slug flow above the stationary solid layer and the moving solid layer, respectively. The effects of L-valve geometric parameters on the solid flow characteristics are also investigated. The results indicate that reducing the diameter and length of the horizontal section of L-valve can improve the solid transport efficiency, especially at low aeration velocity. Besides, the solid conveying capacity and flow stability are improved when the sharp bend of L-valve is modified to be a gradual bend.

Numerical simulation on gas-solid flow during circulating fluidized roasting of bauxite by a computational particle fluid dynamics method

A full-cycle numerical simulation of a circulating fluidized bed(CFB)by the use of the computational particle fluid dynamics(CPFD)method has been developed.The effects of the presence or absence of the secondary air,different secondary air positions,and different secondary air ratios on the gas–solid flow characteristics were explored.The results show that the presence of the secondary air makes a core-annular structure of the velocity distribution of particles in the fluidized bed,which enhances the uniformity of particles’distribution and the stability of fluidization.The position and the ratio of the secondary air have a significant impact on the particle distribution,particle flow rate,and gas flow rate in the fluidized bed.When the secondary air position and ratio are optimal,the particles,particle flow rate,and air flow rate in the CFB are evenly distributed,the gas–solid flow state is good,and the CFB can operate stably.

Calculation of circulation in the South China Sea during summer of 2000 by the modified inverse method

On the basis of hydrographic data obtained in August 2000 cruise, the circulation in the South China Sea (SCS) is computed by the modified inverse method in combination with SSH data from TOPEX/ERS-2 analysis. For study of the dynamical mechanism, which causes the pattern of summer circulation in the SCS, the diagnostic model (Yuan et al. 1982. Acta Oceanologica Sinica,4(1):1-11; Yuan and Su. 1992. Numerical Computation of Physical Oceanography.474-542) is used to simulate numerically the summer circulation in the SCS. The following results have been obtained. (1) The central and southwestern SCSs are dominated mainly by anticy-clonic circulation systems. They are mainly as follows. 1) There is strong anticyclonic eddy southeast of Vietnam (W1). Its horizontal scale is about 300 km, and it extends vertically from the surface to the about 1 000 m level. 2) There are a warm eddy W2 southeast of Zhongsha Islands and the anticyclonic circulation system W3 west off the Luzon Island. 3) There is a stronger cyclonic eddy C1 between the anticyclonic eddies W1 and W2.4) A strong northward coastal jet is present near the coast of Vietnam, and separates from the coast of Vietnam at about 12° N to the northeast.(2)The northern SCS is dominated mainly by a cyclonic circulation system. There is a cyclonic circulation system near and north of Section N2. (3) The southeastern SCS is dominated mainly by the cyclonic circulation system. (4) Comparing the results of circulation in the SCS during the summer of 2000 with those during the summer of 1998, it is found that they agree qualitatively, but there is the some difference between them in quantity.This shows that the circulation in the SCS has obviously seasonal feature. (5) The dynamical mechanism which products the basic pattern of summer circulation is because the following two reasons: 1) the joint effect of the baroclinity and relief (JEBAR) is essential dynamical cause; and 2) it is next important dynamical cause that the interaction between the wind stress and bottom topography under the southerly monsoon. (6) Comparing the hydrographic structure and distribution of stream functions with the SSH data from TOPEX/ERS-2 analysis in the SCS during August of 2000, they agree qualitatively.

Synthesis of Substituted u-Oxo-bis[tetra-phenyl porphyrinatoiron] Compounds from Free Base Porphyrins by a One-pot Method

A novel method for synthesis of substituted u-oxo-bis[tetraphenyl porphyrinatoiron] compotmds （[TRPPFe]20） based on the reaction among free base porphyrins （TRPPH2）, FeSO4·7H2O and H2O in one pot was proposed and investigated. Four kinds of [TRPPFe]2O were synthesized by this novel synthetic method, and their structures were characterized by elemental analysis, infrared spectra and UV-vis spectroscopy. The reaction conditions, including the effect of different iron salts on the formation of [TRPPFe]2O, the reaction time between FeSO4-7H2O and TRPPH2, the molar ratio of FeSO4-7H2O/TRPPH2 as well as the volume ratio of H2O/DMF, were investigated. The [TRPPFe]2O yield of 93% 98% could be obtained under the following optimal conditions： the reaction time of FeSOn-7H2O with TRPPH2 was about 10 h, the molar ratio of FeSOn-7H2O/TRPPH2 about 5 ： 1, and the volume ratio of H2O/DMF exceeded 2 ： 1. Further research indicated that only TRPPFeCI were formed once FeSOn-7H2O was replaced by FeCl2-4H2O, the reason of which might be that halogen ions in iron salts interfered the formation of [TRPPFe]2O, suggesting that halogen ions should be avoided in this novel synthetic method.

MIC in Circulating Cooling Water System

MIC is one of the main problems of circulating cooling water system. The direct economic loss by MIC is about 300 to 500 billion dollars. It is good to understand MIC in order to control MIC. Source and species of microorganisms was introduced firstly. There are three kinds of microorganisms in the system, including bacteria, fungi and algae. Species of these microorganisms are shown in the paper. Then, mechanisms of MIC are analysed. Although there is no universal mechanism of MIC, MIC is still mainly an electrochemical corrosion in nature. Meanwhile, the mechanisms on SRB and iron bacteria are introduced in details. At last, several methods of microorganisms control are put forward in the paper.

A New Circulant Preconditioned GMRES Method for Solving Ordinary Differential Equation

The preconditioned generalized minimal residual(GMRES) method is a common method for solving non-symmetric,large and sparse linear systems which originated in discrete ordinary differential equations by Boundary value methods.In this paper,we propose a new circulant preconditioner to speed up the convergence rate of the GMRES method, which is a convex linear combination of P-circulant and Strang-type circulant preconditioners. Theoretical and practical arguments are given to show that this preconditioner is feasible and effective in some cases.

A Method for Diagnosing the Secondary Circulation with Saturated Moist Entropy Structure in a Mature Tropical Cyclone

Under the adiabatic, axisymmetric and steady assumption, a relationship between the saturated moist entropy structure and the secondary circulation in a tropical cyclone(TC) is derived from the continuity equation. It is found that the isentropic surfaces coincide with the streamlines, and the streamfunction can be expressed with saturated moist entropy. The secondary circulation and the saturated moist entropy structure depend on each other. Thus, a method for diagnosing the secondary circulation with the structure of saturated moist entropy is proposed. The method is verified with a simulated intense idealized TC with a highly axisymmetric structure. The diagnosed secondary circulation reproduces well the moist inflow in the boundary layer and the moist updraft in the eyewall. This method facilitates secondary circulation diagnosis in theoretical or mature TCs that satisfy the adiabatic, axisymmetric and steady approximations.

FINITE ELEMENT ANALYSIS FOR THE UNSTEADY NEARSHORE CIRCULATION DUE TO WAVE－CURRENT INTERACTION（II）──TWO－STEP EXPLICIT FINITE ELEMENT METHOD

In this paper, the two-step explicit finite element analysis for the numerical modelof the unsteady nearshore circulation proposed in Ref [ 1]and its realization of Fortranprogram are presented.A circulation has been clearly shown in the calculated wave-current velocity field,and it is in good agreement with observations

Analysis of the Lost Circulation Problem

The well-known“lost circulation”problem refers to the uncontrolled flow of whole mud into a formation.In order to address the problem related to the paucity of available data,in the present study,a model is introduced for the lost-circulation risk sample profile of a drilled well.The model is built taking into account effective data(the Block L).Then,using a three-dimensional geological modeling software,relying on the variation function and sequential Gaussian simulation method,a three-dimensional block lost-circulation risk model is introduced able to provide relevant information for regional analyses.

钻井过程中井漏特征精细识别方法研究与应用

井漏是钻井工程中普遍存在的井下复杂问题,严重影响着钻井施工安全与钻井周期,井漏特征精细识别是高效治理井漏的关键。首先,综合测井、钻井、录井及地质等资料,结合漏层力学性质与物理机理分析,利用加权系数法,建立了基于“井漏综合指数”的井漏层位识别新方法。然后,研究了漏失通道类型及尺寸、漏失压差、漏失速度等井漏特征参数的定量分析方法,并给出计算模型,形成了多信息融合的井漏特征精细识别方法。该方法在X区块进行了实例分析,分析结果表明,X区块实际井资料的处理结果与现场实际漏失地层的层位、漏失类型及漏失速度等井漏特征基本吻合。井漏特征精细识别方法综合考虑了井漏的主要影响因素,利用其可以准确识别漏层的特征,为防漏堵漏技术优化及施工提供科学依据。

The Possibilities of Using the Minimax Method to Diagnose the State of the Atmosphere

The article is devoted to the discussion of the possibilities of approbation of one of the probabilistic methods of verification of evaluation works-the minimax method or the method of establishing the minimum risk of making erroneous diagnoses of the instability of the planetary boundary layer of air.Within the framework of this study,the task of probabilistic forecasting of diagnostic parameters and their combinations,leading in their totality to the formation of an unstable state of the planetary boundary layer of the atmosphere,was carried out.It is this state that,as shown by previous studies,a priori contribution to the development of a number of weather phenomena dangerous for society(squalls,hail,heavy rains,etc.).The results of applying the minimax method made it possible to identify a number of parameters,such as the intensity of circulation,the activity of the Earth’s magnetosphere,and the components of the geostrophic wind velocity,the combination of which led to the development of instability.In the future,it is possible to further expand the number of diagnosed parameters to identify more sensitive elements.In this sense,the minimax method,the usefulness of which is shown in this study,can be considered as one of the preparatory steps for the subsequent more detailed method for forecasting individual hazardous weather phenomena.

钻井法凿井气-液-固耦合排渣流场及刀盘吸渣口优化

针对西部地区侏罗系地层煤矿立井钻井法施工中出现的气举反循环洗井排渣与钻进效率低下问题,以陕西可可盖煤矿中央回风立井ϕ4.2 m超前钻井为工程背景,基于CFD-DEM(计算流体力学和离散单元法耦合)研究方法,建立了气-液-固多相耦合排渣数值模型,揭示了排渣管内、井底流场的速度及压力分布规律,并基于自研的气举反循环排渣试验装置,采用PIV(粒子图像测速法)测试技术对流场分布的正确性进行验证;提出了优化刀盘吸渣口评判指标和方法,对吸渣口的数量、长径比、面积比、总面积占比进行优化,得到了超前钻头刀盘吸渣口布置的最佳方式和相关参数;讨论了钻头转速、注气量、风管没入比和泥浆黏度等主要因素对排渣流场的影响。研究结果表明:(1)排渣管内流体的运移以轴向流动为主,且途经注气端时,流速发生跳跃式剧增;井底流体的运移主要以水平流动为主,流体的垂直上返仅存在于吸渣口附近;井底流体的水平流动以切向流动为主,径向流动仅在吸渣口两侧较为明显,且远离吸渣口处,径流速度较小易产生岩屑沉积;(2)当刀盘吸渣口数量为2,长径比为0.4,面积比为1,总面积占比为1.94%时,吸渣口的布置方式最佳,且清渣率较现行吸渣口布置方式提高66%;(3)增大钻头转速可显著增强吸渣口的吸附作用,注气量、风管没入比与井底和排渣管内流体的轴向速度均呈正相关关系,低黏、低密度的泥浆易获取高流速,但携岩能力较差。研究结果可为破解侏罗系地层深大立井钻井法洗井排渣与钻进效率低下技术难题,提供有益的理论参考。

苏筋通络方结合“行气活血”针刺法治疗急性踝关节扭伤临床观察

目的观察苏筋通络方结合“行气活血”针刺法治疗急性踝关节扭伤临床效果。方法将医院创伤骨科门急诊就诊的102例急性踝关节扭伤患者(2020年5月—2022年7月)纳入研究,以随机数字表法将患者分为两组,每组51例,对照组采取西医常规治疗,观察组采取西医常规治疗同时结合苏筋通络方及“行气活血”针刺法治疗。数据比较:临床治疗效果、中医症状(踝关节疼痛肿胀、皮下瘀斑、关节活动受限等)积分变化、踝关节跖屈活动度与背伸活动度变化、视觉模拟评分(Visual Analogue Scale,VAS)变化、美国足踝外科协会(American Orthopaedic Foot and Ankle Society,AOFAS)踝-后足评分变化、血清疼痛物质(神经生长因子、神经肽、P物质)水平变化、白细胞介素-6(Interleukin-6,IL-6)、白细胞介素-1β(Interleukin-1β,IL-1β)、超敏C反应蛋白(Hypersensitive C-reactive protein,hs-CRP)变化。结果观察组患者与对照组患者治疗总有效率相比[98.04%(50/51)vs86.27%(44/51)],P<0.05;治疗后各组患者中医症状(踝关节疼痛肿胀、皮下瘀斑、关节活动受限等)积分、踝关节跖屈活动度与背伸活动度、VAS评分、AOFAS踝-后足评分、神经生长因子、神经肽、P物质、IL-6、IL-1β、hs-CRP等指标均改善,观察组患者治疗后中医症状(踝关节疼痛肿胀、皮下瘀斑、关节活动受限等)积分、踝关节跖屈活动度与背伸活动度、VAS评分、AOFAS踝-后足评分、神经生长因子、神经肽、P物质、IL-6、IL-1β、hs-CRP等指标均明显优于对照组患者,P均<0.05。结论苏筋通络方结合“行气活血”针刺法治疗急性踝关节扭伤临床效果显著,患者经治疗后临床症状显著改善,疼痛缓解,踝关节功能改善,值得应用。

基于调控免疫炎症微血管损伤的补气活血法治疗肺炎“瘥后防复”思路的提出

肺炎恢复期后遗症严重影响患者身心健康,存在二次感染的风险,且与基础病相互影响导致恶性循环。做好肺炎恢复期康复工作,减少后遗症并预防反复发作是疾病防治的首选。研究显示肺炎长期后遗症和反复发作的机制可能与持续的机体免疫抑制和全身微炎症状态及微血管损伤有关。团队根据传统中医理论,结合长期临床与基础研究,提出“气虚血瘀”是肺炎恢复期的核心病机。因此,团队提出补气活血法治疗肺炎“瘥后防复”的机制与调控免疫炎症微血管损伤有关,调控T淋巴细胞紊乱提高免疫、抑制炎症因子改善机体微炎症状态和抗氧化保护内皮细胞调控微血管损伤,阐明其内在机制将为中医药治疗呼吸系统重大感染性疾病提供理论依据,传承精华、守正创新。

ABC组间循环CBL教学法在胸外科临床见习教学中的应用

目的:探讨ABC组间循环CBL教学法在临床胸外科见习教学中的应用效果。方法:将同年级的临床本科生随机分为对照组(CBL教学法)和试验组(ABC组间循环CBL教学法)。通过对学生们专科测验成绩的比较,学生参与度的分析以及学生对教学的调查反馈,评价ABC组间循环CBL教学法的效果。结果:试验组学生的成绩、主动发言人次数明显高于对照组,未发言人次数明显少于人次数,ABC组学生对自己参与教学过程的满意程度较CBL组更高。结论:ABC组间循环CBL教学法可以提高胸外科临床见习学生的成绩及参与度。

用文献-传播学方法开拓通俗小说研究新局面——《〈水浒传〉成书时间研究:以〈水浒传〉早期传播史料为中心》读后

在《〈水浒传〉成书时间研究:以〈水浒传〉早期传播史料为中心》一书中,作者采用文献-传播学的方法,对李开先《一笑散》、杨慎《词品》、张丑《真迹日录》、钱希言《戏瑕》、陆容《菽园杂记》、潘之恒《叶子谱》、熊过《故相国石斋杨公墓表》等《水浒传》早期传播史料加以考辨。此举兼具文献及其传播的时效性价值与历史性价值,有助于学界转变思路,客观讨论《水浒传》的成书时间。