具有气体阻透性能的干式复合薄膜用黏结剂——MAXIVE

在中国有1000kt双向拉伸聚丙烯薄膜（OPP）被用作食品包装材料。虽然被普遍用作包装材料，但是其缺点是没有气体阻透性。如果黏结剂有气体阻透性便可以生产出便宜的阻透薄膜，降低阻透薄膜的成本。一般的食品包装用阻透薄膜，通常是基材中有阻隔层，然后和密封胶贴合；或者是在无拉伸薄膜中加入阻隔层。

PBAT/PPC多层共挤薄膜的制备及其阻透性能研究

以聚碳酸亚丙酯(PPC)和聚对苯二甲酸-己二酸丁二醇酯(PBAT)为原料,采用多层共挤吹塑的方法制备了全生物降解高阻透性3层复合薄膜PBAT/PPC/PBAT。讨论了PPC层厚度、PBAT层厚度及在一定挤出量时,薄膜牵引速度对复合薄膜性能的影响。结果表明,与纯PPC薄膜相比,PBAT/PPC/PBAT复合薄膜的拉伸强度和加工性能得到提高,其拉伸强度最大提高了200%;薄膜厚度和分子链的取向度对阻透性有较大影响,当PPC层厚度最大(约为12μm)时,氧气透过率最小,为9.5×10^(-15)cm^3·cm/(cm^2·s·Pa);牵引速度最大,即分子链取向度最大时,氧气透过率最小,为9.52×10^(-15)cm^3·cm/(cm^2·s·Pa)。

Design and analysis of a bisected wheel-based cable climbing robot

To inspect inner wires of the cylindrical cables on a cable-stayed bridge, a new bisected wheel-based cable climbing robot is designed. The simple structure and the moving mode are described and the static features of the robot are analyzed. A cable with a diameter of 139 mm is selected as an example to calculate the design parameters of the robot. For safety energysaving landing in the case of electrical system failure, an electric damper based on back electromotive force and a gas damper with a slider-crank mechanism are introduced to exhaust the energy generated by gravity when the robot is slipping down along the cables. A simplified mathematical model is analyzed and the landing velocity is simulated. For the present design, the robot can climb up a cable with diameters varying from 65 to 205 mm with payloads below 3.5 kg. Several climbing experiments performed on real cables confirm that the proposed robot meets the demands of inspection.

塑料啤酒瓶的开发、应用进展与前景

近年来 ,国外采用各种现代化改性手段提高PET瓶的气体阻透性 ,使之用于一次性啤酒容器。本文综述了新型阻透材料PEN用于可重复使用 /重复灌装啤酒瓶的研究开发、测试和推广应用方面取得的突破性进展。预测塑料啤酒瓶将迅速、稳步增长 。

多级高压液氨泵机封的设计特点及运行情况

对螺旋槽组合式机封的设计特点进行分析，并对运行情况和改进进行介绍。

Ionic Conduction and Fuel Cell Performance of Ba0.98Ce0.8Tm0.2O3-α Ceramic

The perovskite-type oxide solid solution Ba0.98Ce0.8Tm0.2O3-α was prepared by high temperature solid-state reaction and its single phase character was confirmed by X-ray diffraction. The conduction property of the sample was investigated by alternating current impedance spectroscopy and gas concentration cell methods under different gases atmospheres in the temperature range of 500-900 ℃. The performance of the hydrogen-air fuel cell using the sample as solid electrolyte was measured. In wet hydrogen, the sample is a pure protonic conductor with the protonic transport number of 1 in the range of 500-600 ℃, a mixed conductor of proton and electron with the protonic transport number of 0.945-0.933 above 600 ℃. In wet air, the sample is a mixed conductor of proton, oxide ion, and electronic hole. The protonic transport numbers are 0.010-0.021, and the oxide ionic transport numbers are 0.471-0.382. In hydrogen-air fuel cell, the sample is a mixed conductor of proton, oxide ion and electron, the ionic transport numbers are 0.942 0.885. The fuel cell using Ba0.98Ce0.8Tm0.2O3-α as solid electrolyte can work stably. At 900 ℃, the maximum power output density is 110,2 mW/cm2, which is higher than that of our previous cell using Ba0.98Ce0.8Tm0.2O3-α （x〈≤1, RE=Y, Eu, Ho） as solid electrolyte.

Propagation velocity measurement for flame of gas explosion in horizontal tube

In coal industry,gas explosion accidents emerge constantly,causing enormous casualties and poorer material property.In the course of studying gas exploding mechanism,the propagation velocity of the flame wave front is one of the most important factors.A set of flame velocity measuring system was designed according to the horizontal pipelined experimental facility of North University of China to study the effects of the quantity and blockage ratio of the circle ring obstacle on the flame propagation velocity in the inclosed tube.The research results show that the obstacle has obviously accelerating effect on the flame wave of gas explosion With the increase of quantity and blockage ratio of the obstacle,the flame accelerating effect becomes more obvious and the flame accelerating persistence is intenser,of which the effect of the quantity of the obstacle on the flame accelerating persistence is larger,but the effect of the blockage ratio of the obstacle on the flame accelerating persistenceis not obvious.

Mixed Conduction in BaCe0.8Pr0.2O3-α Ceramic

BaCe0.8Pr0.2O3-α ceramic was synthesized by high temperature solid-state reaction. The structural characteristics and the phase purity of the crystal were determined using powder X-ray diffraction analysis. By using the methods of AC impedance spectroscopy, gas concentration cell and electrochemical pumping of hydrogen, the conductivity and ionic transport number of BaCe0.8Pr0.2O3-α were measured, and the electrical conduction behavior of the material was investigated in different gases in the temperature range of 500-900℃. The results indicate that the material was of a single perovskite-type orthorhombic phase. From 500℃ to 900 ℃, electronic-hole conduction was dominant in dry and wet oxygen, air or nitrogen, and the total conductivity of the material increased slightly with increasing oxygen partial pressure in the oxygen partial pressure range studied. Ionic conduction was dominant in wet hydrogen, and the total conductivity was about one or two orders of magnitude higher than that in hydrogen-free atmosphere （oxygen, air or nitrogen）

Dynamic Analysis of Floating-Ring Gas Bearings

The dynamic performances of floating-ring bearing with hydrodynamic/hydrostatic gas lubrication are studied theoretically and some calculated charts of dynamic coefficients are given in the paper. The method of stability analysis is also presented and it is proved that the high speed stability of such bearings is better than other types of gas bearings.

Development of a Remotely Controlled Testing Platform with Low-drag Air-ventilated Hull

This paper addresses the development and testing of a remotely controlled boat platform with an innovative air-ventilated hull. The application of air cavities on the underside of ship hulls is a promising means for reducing hydrodynamic drag and pollutant emissions and increasing marine transportation efficiency. Despite this concept＇s potential, design optimization and high-performance operation of novel air-cavity ships remain a challenging problem. Hull construction and sensor instrumentation of the model-scale air-cavity boat is described in the paper. The modular structure of the hull allows for easy modifications, and an electric propulsion unit enables self-propelled operation. The boat is controlled remotely via a radio transmission system. Results of initial tests are reported, including thrust, speed, and airflow rate in several loading conditions. The constructed platform can be used for optimizing air-cavity systems and testing other innovative hull designs. This system can be also developed into a high-performance unmanned boat.

Micro-organic dust combustion considering particles thermal resistance

Organic dust flames deal with a field of science in which many complicated phenomena like pyrolysis or devolatization of solid particles and combustion of volatile particles take place. One-dimensional flame propagation in cloud of fuel mixture is analyzed in which flame structure is divided into three zones. The first zone is preheat zone in which rate of the chemical reaction is small and transfer phenomena play significant role in temperature and mass distributions. In this model, it is assumed that particles pyrolyze first to yield a gaseous fuel mixture. The second zone is reaction zone where convection and vaporization rates of the particles are small. The third zone is convection zone where diffusive terms are negligible in comparison of other terms. Non-zero Biot number is used in order to study effect of particles thermal resistance on flame characteristics. Also, effect of particle size on combustion of micro organic dust is investigated. According to obtained results, it is understood that both flame temperature and burning velocity decrease with rise in the Biot number and particle size.

Control of combustion area using electrical resistivity method for underground coal gasification

Underground coal gasification （UCG） is one of the clean technologies to collect heat energy and gases （hydrogen, methane, etc.） in an underground coal seam. It is necessary to further developing environ- mentally friendly UCG system construction. One of the most important UCG＇s problems is underground control of combustion area for efficient gas production, estimation of subsidence and gas leakage to the surface. For this objective, laboratory experiments were conducted according to the UCG model to iden- ti[y the process of combustion cavity development by monitoring the electrical resistivity activity on the coal samples to setup fundamental data for the technology engineering to evaluate combustion area. While burning coal specimens, that had been sampled from various coal deposits, electrical resistivity was monitored. Symmetric four electrodes system （ABMN） of direct and low-frequency current electric resistance method was used for laboratory resistivity measurement of rock samples. Made research and the results suggest that front-end of electro conductivity activity during heating and combusting of coal specimen depended on heating temperature. Combusting coal electro conductivity has compli- cated multistage type of change. Electrical resistivity method is expected to be a useful geophysical tool to for evaluation of combustion volume and its migration in the coal seam.

Experimental study on convection heat transfer and air drag in sinter layer

Convection heat transfer coefficient and air pressure drop in sinter layer are important factors for the design of sinter cooling craft. Due to the lack of necessary data, the two parameters are studied by experimental method. The experimental results show that heat conduction of sinter impacts the measurement of convection heat transfer coefficient. Convection heat transfer increases with the increase of air volumetric flow rate. Sinter layer without small particles(sample I) gives higher convection heat transfer coefficient than that with small particles(sample II). Under the considered conditions, volumetric convection heat transfer coefficient is in the range of 400-1800 W/(m3·°C). Air pressure drop in sinter layer increases with the increase of normal superficial velocity, as well as with the rise of air temperature. Additionally, air pressure drop also depends on sinter particle size distribution. In considered experimental conditions, pressure drop in sinter sample II is 2-3 times that in sinter sample I, which resulted from 17% small scale particles in sinter sample II.

Proof of Concept MFD Optimization of the Aftbody Geometry of Axisymmetric Slender Body Based on Wave Drag Considerations

A comprehensive, universally valid, elegant and yet simple method to design slender axisymmetric body of minimum wave drag in transonic and supersonic flows is developed. Computational aerodynamics is also used as a tool for numerical experiments in gaining physical understanding of the drag mechanism due to the geometry of the aftbody, such as the correlation between wave drag and wave distribution of the aftbody geometry. The method utilizes MFD （modified feasible direction） based optimization program, along with the linear slender body aerodynamics, for its elegance and generic optimization convenience. The efforts are focused on inviscid flow. A practical method of reducing the wave drag of a given body is developed for both bodies with pointed end and with base area, using shock wave generator at a particular location on the aftbody. The results show that the MFD optimization program can be effectively utilized in an aerodynamic optimization problem.

Fluids discrimination by ray-path elastic impedance inversion: A successful case from Sulige tight gas field

Existing seismic prediction methods struggle to effectively discriminate between fluids in tight gas reservoirs,such as those in the Sulige gas field in the Ordos Basin,where porosity and permeability are extremely low and the relationship between gas and water is complicated.In this paper,we have proposed a comprehensive seismic fluid identification method that combines ray-path elastic impedance(REI)inversion with fluid substitution for tight reservoirs.This approach is grounded in geophysical theory,forward modeling,and real data applications.We used geophysics experiments in tight gas reservoirs to determine that Brie's model is better suited to calculate the elastic parameters of mixed fluids than the conventional Wood’s model.This yielded a more reasonable and accurate fluid substitution model for tight gas reservoirs.We developed a forward model and carried out inversion of REI.which reduced the non-uniqueness problem that has plagued elastic impedance inversion in the angle domain.Our well logging forward model in the ray-path domain with different fluid saturations based on a fluid substitution model proved that REI identifies fluids more accurately when the ray parameters are large.The distribution of gas saturation can be distinguished from the crossplot of REI(p=0.10)and porosity.The inverted ray-path elastic impedance profile was further used to predict the porosity and gas saturation profile.Our new method achieved good results in the application of 2D seismic data in the western Sulige gas field.

Future Outlook of Artificial Cavity Application for Reducing Hydrodynamic Resistance of Containerships

Absolute commitment to reduce the impact of greenhouse gas emissions while increasing fuel efficiency and power density requires further enhancement of prime mover characteristics and special coatings, but mostly requires compliance with EEDI （energy efficiency design index） measures. For the container shipping industry this represents significant increases in fuel costs that can be mitigated above all by reduction of power demand, that is, of ship frictional resistance. In this respect, this paper discusses advantages attainable by application of the ACS （air cavity system） technology on the basis of recent KSRC （Krylov State Research Centre） studies Savings in operating costs yielded by the enhanced propulsion performance for ships fitted with this system are illustrated by a case study of a containership.