Research on mechanical properties of 22MnB5 steel quenched in a steel die

22MnB5 is one of the most typical hot stamping boron steels. In order to study the effect of austenitizing temperature and holding time on the mechanical properties of hot stamping boron steel 22MnB5, a series of quenching process are done. The tensile strength and hardness of 22MnB5 samples are measured. The results show that 22MnB5 has a good quenching performance, and the tensile strength and hardness of samples quenched in a water-cooled steel die are similar to those of water quenching. The higher tensile strength and HRC hardness are achieved when austenitizing at temperatures of 880–910 °C. Holding at 910 °C for 5 min and then quenching gives rise to a better combination of tensile strength, hardness and ductility.     

Wrinkle analysis of the space inflatable paraboloid antenna

The presence of wrinkles in the membrane is the main factor to induce the reflector surface inaccuracy of the space inflatable antenna. Based on the commercial finite element package ABAQUS, a numerical procedure for membrane wrinkle analysis was set up and used to analyze a space inflatable antenna which was under inner pressure to evaluate its wrinkle characteristics. First, the inner pressure effect on the reflector’s wrinkle pattern was studied thoroughly. As inner pressure increases, both the number and the amplitude of the wrinkles decrease, but the total deformation of the whole reflector surface increases much. Second, the influence of the interactions between antenna’s parts was investigated comprehensively. Any kind of unwanted interaction deteriorates reflector’s wrinkle characteristics. The works are valuable to the development and research of the space inflatable antenna.     

Numerical study on bank effects for a ship sailing in shallow channel

A numerical study on bank effects in shallow channels is carried out by using a first-order Rankine source panel method. A container ship sailing along a vertical bank and a sloping bank at different forward speeds, different water depths and different distances between the bank and the ship hull is taken as example. The sway force and yaw moment acting on the hull are calculated and the influences of the speed, water depth and distance between the bank and ship hull on the hydrodynamic force and moment are analyzed. This study can provide insight into the bank effects, as well as to give guidance on ship manoeuvring and control in restricted waterways, which is helpful to the navigation safety.     

Development of the Inner Spherical CVT for a motorcycle

An Inner Spherical CVT (ISCVT) transfers engine power by utilizing the traction force of the lubricant fluid film on the contact point between concave and convex spherical rolling bodies. Since the concave and the convex contact surfaces of the ISCVT are exactly spherical parts, they have a large circular (not elliptic) contact area, and the ISCVT mechanism has a larger torque capacity, less spin loss, and better stability than other traction drive mechanisms. The IVT (Infinitely Variable Transmission) performances also can easily be embodied in the ISCVT. In this work, we developed a prototype of the ISCVT for a motorcycle with a 125cc single cylinder engine having a maximum torque of 13.73 Nm at 8,000 rpm. The design parameters were determined, and the transmission performances were evaluated by optimal design procedure. The transmission efficiency, the life time, the maximum severe stresses on each part of the ISCVT, and the work needed for varying speed ratio were theoretically investigated, and the efficiency performances were experimentally measured. The manufactured prototype was installed in an actual motorcycle, which was fixed on the test-bench equipped with a dynamometer. The parasitic loss of the prototype and the cross-sectional road load performance were tested. The power efficiency of the simulated prototype was between 87∼92%, and the life span was more than 50,000 hours. The tested overall power efficiency was around 70∼92% under frequent driving conditions, which is an impressive performance in a motorcycle transmission despite the small difference from the simulation.     

抑癌基因p16、Rb的表达与胆囊癌预后的关系

目的　研究抑癌基因 p1 6及Rb的表达与胆囊癌预后的关系。方法　用SP免疫组化法同步检测 41例胆囊癌患者抑癌基因 p1 6及Rb的蛋白表达。 结果　p1 6与Rb蛋白表达阳性组生存率明显优于阴性组。结论　p1 6及Rb在胆囊癌的预后判定中具有重要价值 ,同步检测两者的预后价值优于单一检测。     

A co-integration approach to forecasting container carriers’ time charter rates

A vector autoregressive model was developed for a sample of container carrier time charter rates.Although the series of time charter rates are themselves found non-stationary, thus precluding the use of manymodeling methodologies, evidence provided by co-integration tests points to the existence of stable long-termrelationships between the series. An assessment of the forecasts derived from the model suggests that the spec-ification of these long-term relationships does not improve the accuracy of long-term forecasts. These resultsare interpreted as a corroboration of the efficient market hypothesis.     

Options-Based Multi-Objective Evaluation of Product Platforms

A platform is the set of elements and interfaces that are common to a family of products. Design teams must choose among feasible platform concepts upon which a product family could be based, often involving new technologies. Multiple performance objectives need to be considered. A standard approach is to convert the performance outcomes into financial figures, which can then be weighed against the required investments. However, it is not always possible to transform performance outcomes (benefits) into monetary terms, such as in defense or highly technical projects. A multi-objective form of real-options-based platform selection is developed. Systems are compared based on multiple technical and economic goals, incorporating uncertainty by representing the unknown factors during the subsequent development process with probability distributions. The range of uncertain outcomes is integrated into single expected measures of effectiveness, which can then be applied to select the most appropriate platform and set of support product variants. An application to the design of platform-based families of naval high-speed ships is shown.     

Characteristics of a bubble jet near a vertical wall

A numerical model of a coupled bubble jet and wall was built on the assumption of potential flow and calculated by the boundary integral method. A three-dimensional computing program was then developed. Starting with the basic phenomenon of the interaction between a bubble and a wall, the dynamics of bubbles near rigid walls were studied systematically with the program. Calculated results agreed well with experimental results. The relationship between the Bjerknes effect of a wall and characteristic parameters was then studied and the calculated results of various cases were compared and discussed with the Blake criterion based on the Kelvin-impulse theory. Our analyses show that the angle of the jet＇s direction and the pressure on the rigid wall have a close relationship with collapse force and the bubble＇s characteristic parameters. From this, the application range of Blake criterion can be determined. This paper aims to provide a basis for future research on the dynamics of bubbles near a wall.     

Calculation of hydrodynamics for semi-submersibles based on NURBS

Accurate hydrodynamic calculations for semi-submersibles are critical to support modern rapid exploration and extraction of ocean resources. In order to speed hydrodynamic calculations, lines modeling structures were separated into structural parts and then fitted to Non-uniform Rational B-spline （NURBS）. In this way, the bow and stern section lines were generated. Modeling of the intersections of the parts was then done with the universal modeling tool MSC.Patran. Mesh was gererated on the model in order to obtain points of intersection on the joints, and then these points were fitted to NURBS. Next, the patch representation method was adopted to generate the meshes of wetted surfaces and interior free surfaces. Velocity potentials on the surfaces were calculated separately, on basis of which the irregular frequency effect was dealt with in the calculation of hydrodynamic coefficients. Finally, the motion response of the semi-submersible was calculated, and in order to improve calculations of vertical motion, a damping term was affixed in the vertical direction. The results show that the above methods can generate fine mesh accurately representing the wetted surface of a semi-submersible and thus improve the accuracy of hydrodynamic calculations.     

Large-scale physical controls on phytoplankton growth in the Irminger Sea Part I: Hydrographic zones, mixing and stratification

Hydrographic surveys in three consecutive seasons in the Irminger Sea in 2001/2002 have revealed six physical regimes (zones) in which different surface mixing and spring re-stratification processes dominate. They are the South Irminger Current, the North Irminger Current, the Central Irminger Sea, the Polar-origin East Greenland Current, the Atlantic-origin East Greenland Current and the Reykjanes Ridge. The variations in restratification processes in particular have significant implications for the timing of shallow spring mixed layer development and therefore the timing and strength of the spring bloom. The relative roles of heat and freshwater in controlling re-stratification are examined for each hydrographic zone, and it is shown that the simplest concept of solar warming generating spring stratification is appropriate for the Irminger Current and the central Irminger Sea. However in the East Greenland Current and the Reykjanes Ridge zones, the springtime arrival of fresh or saline water at the surface dominates re-stratification and generates the earliest and strongest spring blooms of the region. In the cool fresh centre of the Irminger Sea the relatively low chlorophyll-a throughout the year cannot be wholly explained by stratification or nutrient concentrations. Details of the annual cycle in temperature, salinity, chlorophyll-a and nutrients are presented for each hydrographic zone.