Cluster observations of large-scale southward movement and dawnward-duskward flapping of Earth’s magnetotail current sheet

In August 2001,Cluster satellites observed that the mid-tail current sheet(CS) moved southward continuously for almost seven hours.Meanwhile,Cluster crossed back and forth the CS repeatedly.This means that the large-scale southward movement of the CS was accompanied by a small-scale CS flapping during this period.Using the minimum-variation-analysis(MVA) method and the multi-spacecraft data,we calculated the normal vector,current density and the magnetic curvature of the CS,the results showed that the CS alternated between flattened CS and tilted CS for several times.Strong dawn-dusk oscillations were found for the tilted CS,which caused the repeated crossings of the center of CS by the satellites.This feature is obviously different from the previous observations of the vertical flapping of the CS induced by the kink instability.Two types of flapping were observed:One of them is accompanied with bursty bulk flows(BBFs) and the other is not.This suggests that in this event there was no direct relationship between the CS flapping and BBFs.     

The matrix representation for the mathematic structure of Shannon’s information measures

The underlying mathematic structure of Shannon’sinformation measures is the fundamental aspectin Infor-mation Theory. Han first raised the question of whatlinear combination of entropies are always nonnega-tive[1]. Hu Guo Ding proved the result that ther…     

Simulation and analysis of effects of Young’s modulus of isolation material on natural frequencies of the sensor package and displacement of the chip

During the last ten years, Micro-electromechanicalSystems (MEMS) technology developed very rapidlyand with that came great achievements. Currently, theMEMS devices are different types of sensors, which areusually applied to measure physical quantities such aspressure, the acoustic signal, mass, motion, accelera-tion, rotation, velocity of flow, chemical reaction, vi-bration, and so on. Additionally, some sensors havebeen manufactured[1]. MEMS packaging technologydevelops slowly due to the…     

Discussion of the Evaluation Method and Value of Green Building’s POE in the Era of Large Data

China vigorously is carrying out the construction of green building and ecological city during ＂ The 12th five-Year plan＂. Now, although the identification system of design and operation have been implemented in the evaluation of green building, lacking of appropriate evaluation after use. The actual operation results of many buildings, which have got a green building logo, are not satisfied from the user,s perspective. In this paper, an evaluation method that combines the actual building energy consumption and users＇ satisfaction has been discussed, based on the post oceupaney evaluation （POE） theory and the Big data technology. Through the comparison and analysis of building objective operational metrics and users subjective feelings indicators, the green buildings＇ POE has been achieved. Finally, the study analyzes the assessed value of green building＇ s POE from the three-time dimensions, short-term, medium-term and long-term. And the outlook of the direetion is looking forward to the follow-up study.     

A mechanical analysis of the constitutive parameters in the semiviscosity flow equations under the superplastic tension conditions

ＴｈｅｓｕｐｅｒｐｌａｓｔｉｃｒｅｓｅａｒｃｈｈａｓｂｅｅｎｔｒａｎｓｆｅｒｒｅｄｆｒｏｍｏｂｓｅｒｖｉｎｇｐｈｅｎｏｍｅｎａｔｏｍｅｃｈａｎｉｃａｌａｎａｌｙｓｉｓｓｉｎｃｅＢａｃｋｆｅｎｅｔａｌ.[1]ｅｓｔａｂｌｉｓｈｅｄｔｈｅｅｑｕａｔｉｏｎσ=ｋεｍ,(1)ｗｈｉｃｈｉｎｄｉｃａｔｅｓｔｈｅｒｅｌａｔｉｏｎｓｂｅｔｗｅｅｎｒｅａｌｓｔｒｅｓｓσａｎｄｓｔｒａｉｎｒａｔｅεｉｎｓｕｐｅｒｐｌａｓｔｉｃｔｅｎｓｉｏｎ,ａｎｄｓｔｒａｉｎｒａｔｅｓｅｎｓｉｔｉｖｉｔｙｉｎｄｅｘｍｉｓｍｅａｓｕｒｅｄｂ…     

Performance analysis and design of self-air-cooling reciprocating compressor’s cooling system

Science China Technological Sciences - The cooling system, as an important part of high-pressure compressor, has always been a key technical bottleneck for its miniaturization. A new type...     

Transparent characterization and quantitative analysis of broken gangue’s 3D fabric under the bearing compression

Broken gangue has been extensively used in rockfill dams, subgrade, embankment, foundation cushion and other engineering construction. The deformation characteristics of broken gangue under the bearing compression play a decisive role in the firmness, stability and safety of these structures (buildings), and the meso-fabric change of broken gangue under the bearing compression significantly affects its macro deformation. In this study, the transparent characterization and quantitative analysis of 3D fabric of broken gangue under the bearing compression were performed through CT scanning test, image processing and 3D reconstruction technology, and the influence mechanism of internal fabric of broken gangue on its macro deformation was revealed. The results show that: In the loading stage of 0–2 MPa, the sharp corners, thin edges on the blocks and the bar-shaped and blade-shaped blocks with poor regularity are broken first under the bearing compression; in the loading stage of 2–8 MPa, a large number of larger particles in the sample are crushed in the mode of fragmentation; in the loading stage of 8–10 MPa, the breakage degree of samples is relieved. The axial displacement of the block inside the sample occurs, as well as the lateral displacement of the block converging to the central axis of the sample. In the rapid deformation stage, the macro deformation of the broken gangue is mainly caused by the rearrangement and adjustment of the block structure and the breakage of the block; in the slow deformation stage, it is mainly caused by the breakage of the block; in the stable deformation stage, it is mainly caused by the optimization and adjustment of the bearing skeleton in the sample.     

The foundation and analysis of polarized magnetic system’s unified mathematical model in aerospace electromagnetic relay

Polarized magnetic system has a series of features, such as small volume, light weight, low power consumption, high sensitivity, quick movement and so on, widely used in the products of the military aerospace electromagnetic relay. The typical polarized magnetic system has mainly four structures and its simplified equivalent magnetic circuits model is the base of the design of the electromagnetic relay with permanent magnet. In the past, the analysis method that people used was difficult to build the unified mathematical models, which divided the work gap magnetic flux into "permanent magnet flux" and "electromagnetic flux". Based on the analysis method of the work gap magnetic voltage, this paper founds the unified mathematical model of the polarized magnetic system and divides the attractive torque into permanent magnet torque, polarized torque and electromagnetic torque through the energy balance formula. It analyses the influence of permanent magnet sizes on permanent magnet torque, polarized torque and electromagnetic torque through the energy balance formula and the conclusions can direct the design of aerospace electromagnetic relay with permanent magnet.     

Ion acceleration at dipolarization fronts associated with the interchange instability in Earth’s magnetotail

Science China Technological Sciences - It has been confirmed that dipolarization fronts (DFs) are the result of the interchange instability in the Earth’s magnetotail. In this paper, we use a...     

Orthogonal analysis of water model study on the optimization of flow control devices in a six-strand tundish

Improper flow control devices in a multi-strand tundish can cause some problems, for example, liquid steel cannot reach every nozzle at the same time and the liquid steel in nozzles far away from the entry zone has a lower temperature. The water model experiment of a six-strand tundish of Tianjin Iron ＆ Steel Co. Ltd. was performed, a new ＂U＂ type baffle was obtained, and its parameters were defined by perpendicular analysis. The ＂U＂ baffle can not only improve those imperfections, but also prolong the residence time of nonmetallic inclusions, which is good for their flotation and separation.     

Design of the multirobot intelligent team formation＇s control architecture and performance analysis of the system

The layered control architecture is designed for the need of the multirobot intelligent team formation. There are three levels：the cooperation task level, the coordination behavior level and the action planning level. The cooperation task level uses the potential grid method, which improves the safety of the path and reduces the calculation complexity. The coordination behavior level uses the reinforcement learning which can strengthen the robots＇ intelligence. The action planning level uses the fuzzy planning methods to realize the action matching. The communication model transfers the message in different level. This architecture shows not only the independence and the intelligence of the single robot but also the cooperation and the coordination among the robots. In each level, the task is distributed reasonably and clearly. Finally the feasibility of the architecture is verified further in the simulation of the experiment. The expansibility of the architecture is good and the architecture can be used in the similar system.     

XRD and TEM analysis of the microstructure in the brazing joint of 3003 cladding aluminum alloy

The material used in this experiment was 3003 cladding aluminum alloy, the cladding metal was 4004 aluminum alloy. The aluminum plate was brazed by means of vacuum brazing. The microstructure in the brazing joint was studied by means of X-ray diffractometry (XRD) and transmission electron microscopy (TEM). The test result indicates that the suitable brazing technique parameters are brazing temperature, 628°C; keeping time, 10 min; vacuum degree, 6.5×10-4 Pa. XRD test indicates that there are new intermetallic compounds different from the base metal. TEM analysis indicates that Cu2Mg and Cu3Mn2Mg are formed in the brazing joint. The shape of Cu2Mg is irregular and the shape of Cu3Mn2Mg is circle, and there are tiny particles in it.     

Simulation and analysis of effects of Young＇s modulus of isolation material on natural frequencies of the sensor package and displacement of the chip

For the first time an anti-shock packaging model of an acoustic-vibration sensor system has been designed by using the shocking isolation principle. The finite element analysis has been applied for design and simulation of the model. The effects of Young‘s modulus of anti-shock rubber on naturally occulting frequencies of the combination of rubber and an acoustic sensor chip were analyzed. The displacement of the acoustic sensor chip is loaded with force. The results of static analysis and harmonic analysis show that while increasing Young‘s modulus of anti-chock rubber, the first five natural frequencies of the package body also increases. Yet the displacement of the acoustic sensor chip around the resonant frequency decreases. The results of static and transient analysis show that the displacement of the acoustic sensor chip decreases with the increase of Young‘s modulus of anti-chock rubber being loaded with either transient force or static force at the bottom of the combination of rubber and acoustic sensor chip.     

Utility and Weight of Factors of Bus Transit’s Service Quality Analysis in Nanjing

Service quality is a major factor that affects how public transport users evaluate bus service. In order to evaluate how bus users make trade?offs across travel cost, time, reliability, etc., and to in...     

Mechanism of petroleum migration and accumulation in western China’s superposed basins

In western China, most petroliferous basins are superposed due to their multi-periodic tectonic evolution, and the mechanisms of petroleum migration and accumulation are so complex that much more sophisticated methodologies are necessary for depiction of these mechanisms and identification of petroleum occurrences. For this purpose, in this article, a new methodology was formulated which includes: (1) vertical identification of petroleum migration and accumulation fluid dynamic systems in the superposed basins; (2) analysis of the effect of large scale regional faults and fault combinations on the fluids exchange between the vertically identified different systems; (3) analysis of petroleum migration and accumulation in each vertically identified system, and establishment of appropriate geological model of petroleum migration and accumulation for each vertically identified system. Using this methodology, the satisfactory results obtained in the Lunnan Uplift of Tarim Basin and Ludong Uplift of Jungar Basin case studies are: (1) existence of different vertical fluid dynamic systems in western China’s superposed basins which are very necessary for understanding the mechanism of petroleum migration and accumulation; (2) in deep system, long-distance lateral petroleum migration and accumulation mainly take place along the long time exposed unconformity with weathered, fractured or karst reservoir rocks; (3) regional faults are the main conducts for fluids migration from deep system up to middle and/or upper systems. As to middle and/or upper systems, regional faults play a role of “petroleum source”. Small faults within middle and/or upper systems conduct petroleum to carrier beds with less impeding force; (4) petroleum migrated from deep system vertically up to middle and/or upper systems will migrate laterally in carrier beds of these systems and accumulate to form pools near or far from faults.     

Prediction of a V-8 diesel engine’s structural radiated noise and research of important parameters’ effects on the engine’s acoustic behaviors

Based on the coupled boundary element method-finite element method(BEM-FEM)method and the acoustic transfer vector(ATV)technology,BEM/FEM model is proposed for a V-type eight cylinders engine acoustic radiation simulating analysis under semi-anechoic condition.Acoustic radiation power,field points sound pressure level and panel contributions are calculated by acoustic radiation response analysis.Additionally,based on the engine acoustic performance,different acoustic behaviors of engine are studied by changing engine materials,oil pan structures as well as geometry parameters.The acoustic performance of this engine is predicted and the influence of material,structural and geometry parameters on engine radiated noise are generalized.The principle will guide the design and optimization of the engine prototype in further work.     

Numerical calculation of flow and heat transfer process in the new-type external combustion swirl-flowing hot stove

It is clarified that the important method to improve the blast temperature of the small and the middle blast furnaces whose production is about two-thirds of total sum of China from 1000℃ to 1250-1300℃ is to preheat both their combustion-supporting air and coal gas. The air temperature of blast furnaces can be reached to 1250-1300℃ by burning single blast furnace coal gas if high speed burner is applied to blast furnaces and new-type external combustion swirl-flowing hot stove is used to preheat their combustion-supporting air. The computational results of the flow and heat transfer processions in the hot stove prove that the surface of the bed of the thermal storage balls there have not eccentric flow and the flow field and temperature field distribution is even. The computational results of the blast temperature distribution are similar to those determination experiment data. The numerical results also provide references for developing and designing the new-type external combustion swirl-flowing ho     

Simulation and analysis of a Truck Model’s ride comfort based on fuzzy adaptive control theory

With the development of national highroad and theincreasing of transportation of passenger and cargo,au-tomobile’s handing stability,ride comfort and securityare demanded highly,and vehicle with air suspensionis used widely.By EC technical development,au…     

Adsorption of sulfate in aqueous solutions by organo-nano-clay： Adsorption equilibrium and kinetic studies

The adsorption of sulfate in aqueous solutions onto organo-nano-clay prepared by natural zeolite and cationic surfactant cetyltrimethylammonium bromide （CTAB） was studied.Parameters such as adsorbent dosage,contact time and temperature were investigated using batch adsorption studies.The results show that the uptake of sulfate increases with the increase of contact time and temperature,and decreases with the increase of dosage.The Freundlich isotherm model is fit to explain the sulfate adsorption onto organo-nano-clay.The maximum adsorption capacity is found to be 38.02 mg/g at 40 ℃.The kinetic data fit well the pseudo-second-order and Elovich models with a R2 more than 0.98.It is suggested that chemisorption is the rate-controlling step for adsorption of sulfate onto organo-nano-clay,meanwhile both intraparticle diffusion and boundary layer diffusion also contribute as well.Ion-exchange between sulfate anions and bromide ions and complexation between sulfate anions and CTAB cations are responsible for the mechanism of sulfate adsorption.
Keywords：organo-nano-clay; cetyltrimethylammonium bromide （CTAB）; modification; sulfate; adsorption