Steel slag waste combined with melamine pyrophosphate as a flame retardant for rigid polyurethane foams

To explore the potential application of industrial waste, steel slag powder in combination with melamine pyrophosphate (MPP) was adopted to improve the flame retardancy of rigid polyurethane foam (RPUF). The incorporation of steel slag slightly reduced the thermal conductivity of the resulting flame-retardant RPUF samples. The addition of MPP and/or steel slag did not significantly alter the thermal stability in terms of T_-10% and T_max but did obviously increase the T_-50% value, suggesting the improved thermal resistance of the residues. The coaddition of MPP and steel slag into RPUF resulted in higher LOI values and lower peak heat release rates than the samples incorporating either MPP or steel slag alone. The superior flame retardancy could be attributed to MPP promoting char formation, which then acted as a barrier at the beginning of RPUF thermal decomposition; simultaneously, the thermally stable inorganics in the steel slag powder strengthened the thermal resistance of this char layer.     

光固化3D打印离型膜在树脂作用下的变形分析

在光固化光敏树脂成型过程中,聚四氟乙烯离型膜会在树脂液位的波动影响下发生变形,进而影响光固化制件的精度,因此需要减小离型膜在制件过程的变形量,确保其相对稳定。首先分析树脂液位变化,通过液位变化量,等效出树脂液波动带给离型膜的载荷,建立离型膜受力模型。然后基于离型薄膜的挠度变形理论,应用Ansys软件进行模拟研究,对不施加预应力和施加不同预应力作用下的离型膜变形结果分析,结果表明施加预应力有利于提高离型膜稳定性,且施加预应力为2. 645M Pa时离型膜受到树脂波动影响最小,位置精度变化在0. 01 mm。     

Numerical investigation of light gas release,stratification and dissolution in TH22 test facility using 3-D CFD code GASFLOW-MPI

An accurate prediction of the hydrogen behaviors in the accident and management process is a crucial topic for both the hydrogen safety assessment and safety analysis in the confined enclosure like the containment of the nuclear power plant (NPP). Hence, the hydrogen behaviors including the transient light gas release, stratification and dissolution in the TH22 test facility for the NPP containment are analyzed and compared using the 3-D CFD code GASFLOW-MPI in this study. In this paper, the light gas helium is adopted as a substitute for the hydrogen in the calculations in accordance with the experiment. Firstly, the detached eddy simulation (DES) turbulence model, 3-D numerical model and experiment setup are introduced. Then, the hydrogen behaviors with the GASFLOW-MPI including the light gas release, stratification and dissolution are analyzed and validated with the experiment data. In addition, the velocity profiles, light gas concentrations, dimensionless numbers and temperature distributions are evaluated for the characteristics of the hydrogen behaviors. The results indicate that the calculation results agree well with the experiment data. Foremostly, the relative errors between the calculation results and experiment data during the phase of the dissolution of the light gas cloud are within 11.9%. Meanwhile, the relative errors of the time for the complete dissolution during the phase of the dissolution of the light gas cloud are within 5.0%. For the light gas release and stratification phase, the jet flow dominates as the Froude (Fr) number exceeds 10 during the time t = 600 s–800 s. Additionally, the time averaged centerline velocity and light gas concentration after the potential core region decay with a slop of 1/z which coincide with the theoretical jet limit. Lastly, the light gas concentrations and temperature distributions in all three phases are captured clearly with the GAFLOW-MPI. It demonstrates that the GASFLOW-MPI can accurately described the details of the related hydrogen behaviors in the accident and management process in the confined enclosure like the NPP. This paper can provide guidance for the numerical computation of the hydrogen safety issues in the confined space.     

Microanalysis of supersaturated gas release based on wall-attached bubbles

Supersaturation of dissolved gases in natural water, due to spillage from high dams and other factors, may cause fish mortality. In previous experiments, the dissipation coefficient has been used to denote the degassing process of total dissolved gas(TDG) saturation. These experiments mainly analyzed supersaturated TDG dissipation from a macroscopic view. To precisely clarify the mechanism of supersaturated TDG release, this study investigated bubble adsorption at a wall surface from a microscopic view. The experiment was conducted in a Plexiglas-wall container filled with supersaturated TDG water. A model that calculates the adsorption flux of supersaturated TDG by a solid wall, and helps describe construction for a contact angle at a three-phase intersection, was developed according to Young's equation. This model was used to investigate the formation process of bubbles adsorbed on a solid polymethyl methacrylate(PMMA) surface in supersaturated TDG water. The adsorption effect of a solid wall on TDG release was analyzed based on the experimental data. The modeling results were compared with observations under different wall area conditions, and it was found that TDG release tended to increase with wall area. This study helps improve our understanding of the mechanisms of supersaturated TDG release and provides an important theoretical method for accurate calculation of the release process. The adsorption flux model of the solid wall provides mitigation measures to combat the adverse effects of TDG supersaturation,which will be beneficial to the protection of aquatic organisms in hydropower-regulated rivers.     

台湾农地释出政策对国土资源合理开发利用的启示

本文回顾了1993年以来的台湾农地释出政策演进历史,分别从探索中的释出阶段、转型期的理性释出阶段和新"国土"功能分区下的农地释出阶段对这一过程进行解读;揭示了台湾农地释出政策经历了从工商业用地需求导向到注重农用地整体统筹规划利用,从关注台湾本土发展转型到因应国际形势变化的发展历程;进而讨论了对大陆建设用地合理扩张和耕地保护的启示。     

Acrylic Resins as Rate-Controlling Membranes in Novel Formulation of a Nine-Day 17β-Estradiol Transdermal Delivery System: In Vitro and Release Modifier Effect Evaluation

The feasibility of transdermal controlled delivery system of 17 β-estradiol was investigated by conducting in vitro release studies. Several new 17 β-estradiol unilaminate adhesive devices capable of releasing 17 β-estradiol in a controlled fashion over a 24-h, 36-h, 96-h, 104-h, 168-h, and 216-h period have been developed using acrylic resins (Eudragits E100, RSPO, and RLPO) as adhesive and rate-controlling polymers. The in vitro release profiles of 17 β-estradiol from various TDS unilaminate devices were characterized in a new developed dissolution tester vessel (total volume 200 ml), using a new paddle. The release of drug from different formulations was measured by a sensitive high-performance liquid chromatographic (HPLC) method. The release of drug from all prepared adhesive devices seems to obey zero-order kinetics (r > 0.98). The effect of two different plasticizers (acetyltributyl citrate [ATBC] and triethyl citrate [TEC]) on the release patterns of 17 β-estradiol from TDS formulations was studied, and they were almost identical. The effect of two different release modifiers, propylene glycol (PG) and myristic acid (MA), on the release pattern of 17 β-estradiol from prepared unilaminate devices was evaluated. It was shown that the use of these release modifiers significantly increased the release of 17 β-estradiol from a TDS unilaminate patch. Furthermore, these data clearly demonstrated that the acrylic resins are suitable polymers for the preparation of 17 β-estradiol TDS adhesive devices.     

Influence of curvature geometry of laminated FRP composite panels on delamination damage in adhesively bonded lap shear joints

Three dimensional non-linear finite element analyses of Lap Shear Joints (LSJs) made with curved laminated FRP composite panels having pre-existing delaminations between the first and second plies of the strap adherend have been carried out using contact and Multi-Point Constraint elements (MPC). Progressive growth of delamination has been simulated by sequential release of the MPC elements. Strain Energy Release Rate (SERR), being an indicative parameter has been computed using Virtual Crack Closure Technique (VCCT) for assessing the growth and propagation of the delamination damage fronts. The inter-laminar stresses and the SERRs at the two fronts of the pre-embedded delamination are found to be significantly influenced by the delamination size. The three individual modes of SERR on the two delamination fronts are found to be much different from each other, indicating dissimilar rates of propagation. The curvature geometry of adherends significantly influences the SERR values. It is seen that decrease of radius of curvature of adherend panels, keeping their widths unchanged, increases the SERR values. Flatter FRP composite adherends have superior resistance to delamination damage propagation as compared to LSJs made with curved composite laminated panels.     

Preparation and In Vitro Evaluation of Chitosan Matrices Cross-Linked by Formaldehyde Vapors

Rifampicin-chitosan matrices were prepared by a chemical cross-linking method to develop a sustained-release form. The effects of cross-linking agent (formaldehyde) on the drug release rate and release kinetics were investigated in this study. Moreover, the kinetics of rifampicin released from chitosan matrices exposed to formaldehyde vapors for predetermined time intervals were analyzed using Ritger and Peppas exponential equation. The in vitro release kinetics exhibited a non-Fickian transport model. Increasing the exposure time to formaldehyde vapors decreased the release rate of rifampicin from chitosan matrices as a result of formation of greater structural strength and tighter texture.     

Inverse identification of the release location,temporal rates,and sensor alarming time of an airborne pollutant source

With an accidental release of an airborne pollutant, it is always critical to know where, when, and how the pollutant has been released. Then, emergency measures can be scientifically advised to prevent any possible harm. This investigation proposes an inverse model to identify the release location, the temporal rate profile, and the sensor alarming time from the start of a pollutant release. The first step is to implement the inverse operation to the cause–effect matrix to obtain the release rate profiles for discrete candidate scenarios with concentration information provided by one sensor. The second step is to interpret the occurrence probability of each solution in the first step with the Bayesian model by matching the concentration at the other sensor. The proposed model was applied to identify a single pollutant source in a two‐dimensional enclosure using measurement data and in a three‐dimensional aircraft cabin with simulated data. The results show that the model is able to correctly determine the pollutant source location, the temporal rate profile, and the sensor alarming time. The known conditions for input into the inverse model include a steady flow field and the valid temporal concentrations at two different locations.     

贵州广播电视台播出建设思路以及对未来播出的思考

本文从总体架构、业务流程、网络架构、关键点设计这几个建设要点进行阐述，介绍了贵州广播电视台的播出建设思路；同时通过引入4K播出、IP化、超融合架构、全媒体发布等前沿技术，进行对未来播出技术架构的展望。