Universal hierarchical symmetry for turbulence and general multi-scale fluctuation systems

Scaling is an important measure of multi-scale fluctuation systems. Turbulence as the most remarkable multi-scale system possesses scaling over a wide range of scales. She-Leveque （SL） hierarchical symmetry, since its publication in 1994, has received wide attention. A number of experimental, numerical and theoretical work have been devoted to its verification, extension, and modification. Application to the understanding of magnetohydrodynamic turbulence, motions of cosmic baryon fluids, cosmological supersonic turbulence, natural image, spiral turbulent patterns, DNA anomalous composition, human heart variability are just a few among the most successful examples. A number of modified scaling laws have been derived in the framework of the hierarchical symmetry, and the SL model parameters are found to reveal both the organizational order of the whole system and the properties of the most significant fluctuation structures. A partial set of work related to these studies are reviewed. Particular emphasis is placed on the nature of the hierarchical symmetry. It is suggested that the SL hierarchical symmetry is a new form of the self-organization principle for multi-scale fluctuation systems, and can be employed as a standard analysis tool in the general multi-scale methodology. It is further suggested that the SL hierarchical symmetry implies the existence of a turbulence ensemble. It is speculated that the search for defining the turbulence ensemble might open a new way for deriving statistical closure equations for turbulence and other multi-scale fluctuation systems.

Simulation and visualization of the displacement between CO2 and formation fluids at pore-scale levels and its application to the recovery of shale gas

This article reports recent developments and advances in the simulation of the CO2-formation fluid displacement behaviour at the pore scale of subsurface porous media. Roughly, there are three effective visualization approaches to detect and observe the CO2-formation fluid displacement mechanism at the micro-scale, namely, magnetic resonance imaging, X-ray computed tomography and fabricated micromodels, but they are not capable of investigating the dis- placement process at the nano-scale. Though a lab-on-chip approach for the direct visualization of the fluid flow behaviour in nanoscale channels has been developed using an advanced epi-fluorescence microscopy method combined with a nanofluidic chip, it is still a qualitative analysis method. The lattice Boltzmann method （LBM） can simulate the CO2 displacement processes in a two-dimensional or three-dimensional （3D） pore structure, but until now, the CO2 displace- ment mechanisms had not been thoroughly investigated and the 3D pore structure of real rock had not been directly taken into account in the simulation of the CO2 displacement process. The status of research on the applications of CO2 displacement to enhance shale gas recovery is also analyzed in this paper. The coupling of molecular dynamics and LBM in tandem is proposed to simulate the CO2-shale gas displacement process based on the 3D digital model of shale obtained from focused ion beams and scanning electron microscopy.

Bench and Full Scale Study of Removal Effect and Mutagenicity on Mesocyclops Leukarti with Chlorine Dioxide

Mesocyclops Leukarti of zooplankton propagates excessively in eutrophic water body and it can not be effectively inactivated by the conventional process in drinking waterworks for its special surface structure. In this paper, a study of removal efficiency on Mesocyclops Leukarti with chlorine dioxide in a drinking waterworks was performed. Bench scale results showed that chlorine dioxide is more effective against Mesocyclops Leukarti. And Mesocyclops Leukarti could be effectively removed from water by 1.0 mg/L chlorine dioxide preoxidation cooperated with the conventional process during the full scale study. The chlorite, by.product of prechiorine dioxide, was constant at 0.45 mg/L after filtration, which was lower than the critical value of the USEPA. GC-MS examination and Ames test showed that the quantity of organics and the mutngenicity in the water treated by chlorine dioxide is obviously less than that of prechlorination.

Decentralized Stabilization of Large-scale Uncertain Systems with State-Delays——LMIs Approach

This paper deals with the problem of decentralized robustcontrol for a class of interconnected uncertain systemswith state delays.The parameter uncertainties are un-known but norm-bounded.A new sufficient condition isobtained for each subsystem and overall system to be sta-bilizable via linear memoryless state feedback robust de-centralized controllers.The results depend on the size of the delays and are given in terms of linear matrix ine-qualities,so they are less conservative than those of delay-independent.Moreover,matching condition is not a necessary condition.Finally,an example is presented to illustrative the effectiveness of the proposed method.

Utilization Survey of Livestock Manure Resources in Large-scale Farms of Yangzhou

Based on surveying the conditions of large -scale farms and commercial manure in the each county of Yangzhou city, the situations and problems for utilization of livestock manure resources were grasped. After an analysis of the potential value of livestock manure, the suggestion and strategy for utilization of livestock manure resources were proposed based on the actual conditions in Yangzhou city.

切制工艺小试与中试的比较及思考——以黄芩饮片为例

目的 采用实验室小试和饮片厂中试工艺对黄芩药材进行切制,比较两种工艺的差异,为黄芩片的生产加工标准化提供参考。方法 采用《中华人民共和国药典》(2020年版)黄芩的浸出物及含量测定方法,对黄芩药材及饮片醇溶性浸出物和黄芩苷的含量进行测定;采用课题组前期建立的黄芩高效液相色谱法(High Performance Liquid Chromatography, HPLC)指纹图谱方法对黄芩药材及饮片进行测定;对小试和中试得到的黄芩片进行饮片得率、外观性状、浸出物和黄芩苷含量、指纹图谱及成分转移率的比较。结果 采用小试和中试工艺得到的黄芩片均为薄片,片型相近,外表皮为黄棕色,具有放射状纹理,且浸出物和黄芩苷含量均符合《中华人民共和国药典》规定。小试工艺的饮片得率、浸出物和黄芩苷转移率比中试工艺略高。结论 小试工艺和中试工艺得到的黄芩片质量相对稳定,切制工艺参数设置合理。在黄芩药材的切制工艺中,环境温湿度、水洗次数和蒸制压力是关键因素。小试研究和中试验证的结合,可降低饮片工业化生产风险,为黄芩片的生产加工标准化提供参考。

W-Mn/SiO _2甲烷氧化偶联催化剂流化床的放大研究

在催化剂装量为２００ｍＬ的不锈钢流化床反应器上，Ｗ－Ｍｎ／ＳｉＯ２催化剂甲烷氧化偶联反应性能及稳定性试验结果表明，在甲烷空速为７０００ｈ－１，反应温度为８００℃，原料中氧含量为１１．８％时，Ｃ２烃选择性和收率分别可达８２．６％和１７．８６％；反应温度为８７５℃，Ｏ２含量为１５．１％时，Ｃ２烃收率和选择性分别为１９．４％和７５．７％。在４５０ｈ稳定性试验中，Ｃ２烃的收率和选择性一直在１７％和７０％以上。另外，用ＸＲＤ、ＩＣＰ－ＡＥＳ和ＢＥＴ等手段分别对新鲜催化剂和经稳定性试验后的催化剂进行了表征。

逐级放大制备的TS-1分子筛表征与丙烯直接氧化催化性能对比

采用以络合剂提高钛源稳定性合成钛硅分子筛的方法,在0.2 L,2 L,100 L,2 m3四种不同规模的晶化釜中制备TS-1分子筛,采用XRD,IR,SEM和微结构分析等手段对合成的TS-1分子筛进行表征,考察TS-1分子筛在间歇反应釜中对丙烯直接环氧化的催化效果。结果表明,在四种不同规模晶化釜中合成的TS-1分子筛具有相同的骨架结构,晶形均一,在相同的反应条件下,双氧水转化率与环氧丙烷选择性均在90%以上,逐级放大制备的TS-1分子筛的催化性能基本相当。说明该法制备TS-1分子筛重复性好,易于放大。

以Pd/α-Al_2O_3为催化剂的CO与C_2H_5OH合成草酸二乙酯研究(Ⅰ)

进行了Pd/α-Al_2O_3催化剂上CO与C_2H_5OH气相催化偶合制草酸二乙酯的试验研究,并对自制的几种不同催化剂进行评选。结果表明,B_1型催化剂具有良好的催化活性和选择性。当SV为2500～4000h^(-1)时,草酸二乙酯的时空收率分别为310和450g/L·h。草酸二乙酯和碳酸二乙酯的总选择性在95％以上。B_1型催化剂具有良好的稳定性和工业开发价值。

新型NCG-6苯加氢催化剂的研究与工业放大

应用常压原粒度活性评价装置,对气相苯加氢制环己烷的Ni/Al2O3苯加氢催化剂进行研究评价与条件试验,考察助催化剂、中和条件对催化剂性能的影响;通过实验对比表明,NCG-6型苯催化剂的性能达到并优于各参比催化剂的水平。通过工业放大表明,NCG-6型苯加氢是一种催化活性高、机械强度好、热稳定性提高的新型苯加氢催化剂。

“信噪比-两步法”的一个注记

参数设计是日本质量专家田口倡导的一种质量工程方法.从函数结构方面考察了信噪比指标下调节因子的存在性,并指出了参数设计中scale因子的重要性.

最新版GB/T7722-2005《电子台案秤》新增内容及实施要点

GB/T7722-2005《电子台案秤》已于2005年12月1日正式实施。该标准与原GB/T7722-1995《电子计价秤》和目前执行的JJG555-96《非自动秤通用检定规程》相比较,有较大的区别。本文主要就其区别内容与实施要点逐一进行详尽介绍。

最新版GB/T7722-2005《电子台案秤》新增内容及实施要点

GB/T 7722-2005《电子台案秤》已于2005年12月1日正式实施。该标准与原GB/T 7722-1995《电子计价秤》和目前执行的JJG 555-96《非自动秤通用检定规程》相比较,有较大的区别。本文主要就其区别内容与实施要点逐一进行详尽介绍。

苯乙烯-丙烯酸丁酯胶乳的制备及扩大试验

通过引入活性单体全成了苯乙烯 -丙烯酸丁酯胶乳 ,并进行了扩大试验。讨论了乳化剂用量和类型对胶乳稳定性及粒径的影响。结果表明 ,胶乳的钙离子稳定性取决于非离子乳化剂的用量和类型 ,负离子乳化剂的用量和类型影响胶乳的粒径。用补加引发剂的方法可以提高单体的转化率。生产的胶乳可以用于制备内外墙乳胶漆。

基于3-RPS空间并联机构的发动机支撑台架设计

基于3-RPS空间并联机构原理,分析了该并联机构应用于发动机支撑台架设计中存在的问题,并对3-RPS机构进行改良优化,设计了某发动机支撑台架。实际应用表明,所设计的发动机支撑台架能很好地满足发动机的工作要求。

On the horizontal distribution of algal-bloom in Chaohu Lake and its formation process

Based on the remote sensing images of algae, the present work analyzes the horizontal distribution characteristics of algal blooms in Chaohu Lake, China, which also reveals the frequency of algal blooms under different wind directions. Further, an unstructured-grid, three-dimensional finite-volume coastal ocean model （FVCOM） is applied to investigate the wind-induced currents and the transport pro- cess to explain the reason why algal blooms occur at the detected places. We first deduce the primary distribution of biomass from overlaid satellite images, and explain the formation mechanism by analyzing the pollution sources, and simulating the flow field and transportation process under prevailing wind over Chaohu Lake. And then, we consider the adjustment action of the wind on the corresponding day and develop a two-time scale approach to describe the whole formation process of algae horizontal distribution in Chaohu Lake. That is, on the longer time scale, i.e., during bloom season, prevailing wind determines the primary distribution of biomass by inducing the characteristic flow field; on the shorter time scale, i.e., on the day when bloom occurs, the wind force adjusts the primary distribution of biomass to form the final distribution of algal bloom.

Nonlinear study of the dynamic behavior of a string-beam coupled system under combined excitations

In this paper,the nonlinear dynamic behavior of a string-beam coupled system subjected to external,parametric and tuned excitations is presented.The governing equations of motion are obtained for the nonlinear transverse vibrations of the string-beam coupled system which are described by a set of ordinary differential equations with two degrees of freedom.The case of 1：1 internal resonance between the modes of the beam and string,and the primary and combined resonance for the beam is considered.The method of multiple scales is utilized to analyze the nonlinear responses of the string-beam coupled system and obtain approximate solutions up to and including the second-order approximations.All resonance cases are extracted and investigated.Stability of the system is studied using frequency response equations and the phase-plane method.Numerical solutions are carried out and the results are presented graphically and discussed.The effects of the different parameters on both response and stability of the system are investigated.The reported results are compared to the available published work.

Triboelectrostatic Separation-an Efficient Method of Producing Low Ash Clean Coal

At present, coal is mainly consumed as fuel. In fact, coal is also a kind of precious raw material in chemical industry on the premise that some harmful minerals should be removed from coal. The paper presents the results of the research on producing low ash (<2%) coal with triboelectrostatic separator used for producing high-grade active carbon. The test is conducted in bench-scale system, whose capacity is 30～100 kg/h. The results indicate that: 1) the ash content of clean coal increases with the increase of solid content of feedstock, on the contrary, the yield of clean coal is declining; 2) a high velocity may result in a good separation efficiency; 3) for the same solid content, the reunion caused by intermolecular force makes the separation efficiency drop down when the ultra-fine coal is separated; 4) the separation efficiency is improved with the increase of electric field intensity, but there is a good optimized match between the electric field intensity and yield of clean coal; 5) a low rank coal is easy-to-wash in triboelectrostatic separation process; 6) the yield of clean coal can be enhanced and the ash decreased through adapting optimized conditions according to various coals.

Laboratory investigation of a new scale inhibitor for preventing calcium carbonate precipitation in oil reservoirs and production equipment

The formation of mineral scale is a complex problem during the oilfield operations. Scale inhibitors are widely used to prevent salt precipitation within reservoirs, in downhole equipment, and in production facilities. The scale inhibitors not only must have high effectiveness to prevent scale formation, but also have good adsorption- desorption characteristics, which determine the operation duration of the scale inhibitors. This work is focused on the development of a new scale inhibitor for preventing cal- cium carbonate formation in three different synthetic for- mation waters. Scale inhibition efficiency, optical density of the solution, induction time of calcium carbonate for- mation, corrosion activity, and adsorption-desorption ability were investigated for the developed scale inhibitor. The optimum concentration of hydrochloric acid in the inhibitor was determined by surface tension measurement on the boundary layer between oil and the aqueous scale inhibitor solution. The results show that the optimum mass percentage of 5 % hydrochloric acid solution in the inhi- bitor was in the range of 8 % to 10 %. The new scale inhibitor had high efficiency at a concentration of 30 mg/L. The results indicate that the induction period for calcium carbonate nucleation in the presence of the new inhibitor was about 3.5 times longer than the value in the absence of the inhibitors. During the desorption process at reservoir conditions, the number of pore volumes injected into the carbonate core for the developed inhibitor was significantly greater than the volume of a tested industrial inhibitor, showing better adsorption/desorption capacity.

Formation conditions and exploration direction of large natural gas reservoirs in the oil-prone Bohai Bay Basin, East China

The Bohai Bay Basin is a typical oil-prone basin, in which natural gas geological reserves have a small proportion. In this basin, the gas source rock is largely medium-deep lake mudstone with oil-prone type Ⅱ2-Ⅱ1 kerogens, and natural gas preservation conditions are poor due to active late tectonic movements. The formation conditions of large natural gas fields in the Bohai Bay Basin have been elusive. Based on the exploration results of Bohai Bay Basin and comparison with large gas fields in China and abroad, the formation conditions of conventional large-scale natural gas reservoirs in the Bohai Bay Basin were examined from accumulation dynamics, structure and sedimentation. The results show that the formation conditions of conventional large natural gas reservoirs in Bohai Bay Basin mainly include one core element and two key elements. The core factor is the strong sealing of Paleogene "quilt-like" overpressure mudstone. The two key factors include the rapid maturation and high-intensity gas generation of source rock in the late stage and large scale reservoir. On this basis, large-scale nature gas accumulation models in the Bohai Bay Basin have been worked out, including regional overpressure mudstone enriching model, local overpressure mudstone depleting model, sand-rich sedimentary subsag depleting model and late strongly-developed fault depleting model. It is found that Bozhong sag, northern Liaozhong sag and Banqiao sag have favorable conditions for the formation of large-scale natural gas reservoirs, and are worth exploring. The study results have important guidance for exploration of large scale natural gas reservoirs in the Bohai Bay Basin.