设备状态信息化管理模式的应用

介绍了石钢公司一连轧开展设备状态信息化管理的具体做法。将设备管理与现代化网络相结合,自主开发了设备隐患信息反馈系统,建立了严格的管理制度,使设备隐患得到及时处理,降低了设备故障停机率。     

激光束照射下大芯径SI-PDF光纤传输特性研究

应用于短距离传输的大芯径SI-PDF光纤,必须考虑漏泄光线对光纤传输功率的贡献。本文应用射线光学分析方法,推导了不同入射角的激光束与大芯径SI-PDF光纤的功率耦合传输公式,对不同入射角激光束照射下不同长度SI-PDF光纤的输出功率特性进行了实验研究。给出了在激光束照射下SI-PDF光纤光耦合功率随入射角度的变化关系曲线,并给出不同入射角度激光束在光纤中的损耗系数。结果表明：对大于12°入射的激光束,输出功率随入射角增加成指数衰减规律;不同角度入射激光束在光纤的单位长度内损耗值随角度增大而增大,在12°时损耗值为26 dB/km,在24°时达到了82 dB/km。     

Few‐view image reconstruction combining total variation and a high‐order norm

This work presents a novel computed tomography reconstruction method for few‐view problem based on a compound method. To overcome the disadvantages of total variation (TV) minimization method, we use a high‐order norm coupled within TV and the numerical scheme for our method is given. We use the root mean square error as a referee. The numerical experiments demonstrate that our method achieves better performance than existing reconstruction methods, including filtered back projection, expectation maximization, and TV with projection on convex sets. © 2013 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 23, 249–255, 2013     

Modelling the first- and third-order properties of conceptual thick lenses by using three air-spaced thin lenses

A virtual thick-lens module comprising three air-spaced thin lenses is proposed, which is able to have the identical first-order quantities and third-order Seidel aberrations for just real thick lenses, or groups or components within any thick lens, hence it is capable of studying the aberration behaviours of conceptual lenses without detailed structures. The three thin-lens powers are first evaluated to match the required first-order quantities. Then the aberrations of each thin lens are solved to satisfy the given total aberrations. When the incident rays are changed, each thin lens will induce new aberrations according to the thin-lens formulae. The new system aberrations of the thick module are obtained by adding individual thin-lens aberrations. The module can be directly applied to finite and infinite conjugates, focal and afocal lenses, as well as telecentric and non-telecentric lenses. Examples are given to simulate two real lenses and to optimise the balanced aberrations of a conceptual zoom lens.     

Optimal pricing policy for a deteriorating product by dynamic tracking control

We study the optimal selling price of a deteriorating product under a deterministic situation in a finite time horizon where the time horizon is either known or unknown. Inventory holding cost is expressed as a quadratic function of the current inventory level. Given a known time horizon, we develop a model by considering the deterioration dynamics of the product, and show its equivalence to a generalised optimal control problem of a linear quadratic form, i.e. an optimal dynamic tracking problem with constraints on the control variable. An optimal pricing policy is derived based on the maximum value principle. The control policy takes a state feedback form; it exhibits a closed-loop relationship between the optimal selling price (control variable) and the optimal inventory level (state variable). Given an unknown time horizon, an optimal pricing policy is derived through a similar approach when the initial inventory level meets certain conditions. Numerical situations are conducted to illustrate the effectiveness of the derived price control policies. Some interesting managerial insights are discussed.     

Frictional Pressure Drop for NaK-N2 Two-Phase Flow in Rectangular Cross Section Channel of Large Aspect Ratio

In this paper, the frictional pressure drop in an isothermal liquid metal-gas two-phase flow through a rectangular channel with large width-to-height ratio is treated semiempirically for a NaK-N₂ two-phase flow system.

The frictional pressure drop in the two-phase flow is compared with the following two reference values :

1. The frictional pressure drop in the liquid flowing alone in single phase with the same velocity as that of the liquid in the two-phase mixture.

2. The frictional pressure drop in the liquid flowing alone in single phase with the same mass flow rate as that of the liquid in the two-phase mixture.

The comparison with the former reference value is necessary for the prediction of friction loss in a liquid metal MHD generator channel whose medium would be two-phase mixture.

The semiempirical analysis was performed assuming the two-phase mixture to be a continuous medium with its properties, e.g. viscosity and density, defined by void fraction and the velocity determined by the total mass flow rate.

In the region of low slip and density ratio ρ_g/ρ_l the frictional pressure drop in the two-phase flow appeared to be smaller than that due to the liquid flowing alone with the same velocity as that of the liquid in the two-phase flow.

The experiments have been undertaken with the NaK-N₂ two-phase mixture flowing through a rectangular channel (4 × 60 mm²).

Data were taken over the following parameter range:

NaK velocity: 5～30 m/sec, Void fraction: 0～70%

Density ratio: 0.006～0.013, Quality: 0.07～1.10%.     

Reaction between Uranium Mononitride and Graphite Powders

The carbothermic reaction of UN with graphite in the form of loose powder mixture has been studied in vacuo with the aid of a high-temperature thermobalance in the temperature range of 1,270~1,675°C. The gravimetric measurements were conducted continuously to determine the effect of varying reaction temperature and differences in sample particle size.

The kinetics of the reaction was found to follow the diffusion—controlled kinetic equation for mixed powder, and activation energies of 76.1, 55.1 and 72.7kcal/mol were obtained for samples of (1)—400 mesh UN and—400 mesh natural graphite mixture, (2)—150 +270 mesh UN and—150 +270 mesh natural graphite mixture, and (3)—150 +270 mesh UN and—150 +270 mesh artificial graphite mixture, respectively. X-ray diffraction studies revealed the reaction products of the coarse sample to be composed of two different kinds of UC_xN_1-x solid solutions, one having a x value of 0~0.2, and the other 0.8~0.9. From the above observations, the diffusion of C and/or N atoms through the outer carbon rich UC_xN_1-x layer may be considered to be the rate determining step.     

Monte Carlo Calculations of Source Characteristics of FNS Water Cooled Type Tritium Target

The source neutron characteristics of a water cooled type tritium target at the Fusion Neutronics Source (FNS) facility were calculated using a three-dimensional Monte Carlo method. The angular distribution and the energy spectra of the source neutrons were calculated and compared with the measured results. The comparison showed a reasonable agreement which increased the confidence of both measurement and calculation. The calculated neutron spectra which are free from the detector resolution smearing and which extend to lower neutron energy, will be used as the reference source for the future analyses of the experiments using the present-type water cooled target.