煤仓瓦斯自动排放系统设计及应用

本文主要论述了煤仓瓦斯自动排放系统的系统构成、系统工作原理及其应用效果,指出了该系统在高瓦斯矿井煤仓仓内瓦斯超限治理中具有很好的推广使用价值。     

Identification of Elasto-Plastic Constitutive Parameters by Self-Optimizing Inverse Method: Experimental Verifications

In this paper, the Self-Optimizing Inverse Method (Self-OPTIM) has been experimentally verified by identifying constitutive parameters solely based on prescribed boundary loadings without full-field displacements. Recently the Self-OPTIM methodology was developed as a computational inverse analysis tool that can identify parameters of nonlinear material constitutive models. However, the methodology was demonstrated only by numerically simulated testing with full-field displacement fields and prescribed boundary loadings. The Self-OPTIM is capable of identifying parameters of the chosen class of material constitutive models through minimization of an implicit objective function defined as a function of full-field stress and strain fields in the optimization process. The unique advantages of the Self-OPTIM includes: 1) model independency that is expected to open up a wide range of applications for various engineering simulations; 2) capabilities of parameter identification based solely on global measurements of boundary forces and displacements. In this paper, the Self-OPTIM inverse method is experimentally verified by using two different shapes of specimens made of AISI 1095 steel: 1) dog-bone and 2) notched specimens under a loading and unloading course. Parameters of a cyclic plasticity model with nonlinear kinematic hardening rule and associated flow theory are identified by the Self-OPTIM. Multiple tests and the inverse simulations are conducted to ensure consistent performance of the Self-OPTIM. The identified parameters are successively used to reconstruct the material response.     

Solubility of red palm oil in supercritical carbon dioxide: Measurement and modelling

The solubility of red palm oil(RPO) in supercritical carbon dioxide(scCO_2) was determined using a dynamic method at 8.5–25 MPa and, 313.15–333.15 K and at a fixed scCO_2 flow rate of 2.9 g·min~(-1) using a full factorial design. The solubility was determined under low pressures and temperatures as a preliminary study for RPO particle formation using scCO_2. The solubility of RPO was 0.5–11.3 mg·(g CO_2)~(-1) and was significantly affected by the pressure and temperature. RPO solubility increased with pressure and decreased with temperature. The Adachi–Lu model showed the best-fit for RPO solubility data with an average relative deviation of 14% with a high coefficient of determination, R~2 of 0.9667, whereas the Peng–Robinson equation of state thermodynamic model recorded deviations of 17%–30%.     

Proton-conducting nanocomposite membranes based on P(VDF-co-CTFE)-g-PSSA graft copolymer and TiO2-PSSA nanoparticles

Bifunctional TiO₂ nanoparticles with hygroscopic and proton-conductive properties were synthesized by grafting proton-conducting polymer, i.e. poly(styrene sulfonic acid) (PSSA) from TiO₂ nanoparitlces via surface-initiated atom transfer radical polymerization (ATRP). These bifunctional TiO₂-PSSA nanoparticles were blended with poly(vinylidene fluoride-co-chlorotrifluoroethylene)-graft-poly(styrene sulfonic acid), i.e. P(VDF-co-CTFE)-g-PSSA to give proton-conducting membranes for high temperature fuel cells. FT-IR, UV-visible spectroscopy and X-ray diffraction (XRD) results revealed bifunctional properties of TiO₂-PSSA nanoparticles due to successful grafting of PSSA chains. Ion exchange capacity (IEC) of P(VDF-co-CTFE)-g-PSSA/TiO₂-PSSA membranes was not significantly changed irrespective of TiO₂-PSSA concentrations, representing almost fixed SO₃⁻ concentration in the membranes. In contrast, water uptake and proton conductivity of membranes continuously increased with increasing TiO₂-PSSA concentrations, presumably due to hygroscopic, soft conducting property of nanoparticles. The results of thermal gravimetric analysis (TGA) also showed that all the membranes were stable at least up to 280 °C.     

Assessment of the dietary intake of propylene glycol in the Korean population

An improved method for the analysis of propylene glycol (PG) in foods using a gas chromatography-flame ionisation detector (GC-FID), with confirmation by GC-MS, was validated by measuring several analytical parameters. The PG concentrations in 1073 products available in Korean markets were determined. PG was detected in 74.1% of the samples, in a concentration range from the limit of detection (n.d., 0.39 μg ml^?1) to 12,819.9 mg kg^?1. The Korea National Health and Nutrition Examination Survey (KNHANES) 2011–2013 reported the mean intake levels of PG from all sources by the general population and consumers were 26.3 mg day^?1 (0.52 mg kg^?1 day^?1) and 34.3 mg day^?1 (0.67 mg kg^?1 day^?1), respectively. The 95th percentile intake levels of the general population and consumers were 123.6 mg day^?1 (2.39 mg kg^?1 day^?1) and 146.3 mg day^?1 (2.86 mg kg^?1 day^?1), respectively. In all groups of the general population, breads were the main contributors to the total PG intake. These reports provide a current perspective on the daily intake of PG in the Korean population.     

手薄中存有与基站同名点的危害及解决方案

用GPS进行RTK测量时,有时导航、放样正确,测量的值却是错误的.该类错误产生的原因是放样和测量点时所用的基站点不一样,解决方案是,在一个手薄任务中不要存与基站同名的点.     

Encapsulation of superparamagnetic iron oxide nanoparticles in poly-(lactide-co-glycolic acid) microspheres for biomedical applications

Magnetic microspheres were prepared using a single step coaxial electrohydrodynamic atomization technique at ambient temperature and pressure, with poly(lactic-co-glycolic acid) as the coating and iron oxide (Fe₃O₄) nanoparticles dispersed in polyethylene glycol as the encapsulated material. The morphology and particle size distributions of the prepared magnetic microspheres were investigated by scanning electron microscopy. The particles were spherical with mean diameters ranging from ~ 2 μm to 18 μm, depending on the combination of processing parameters (flow rate and applied voltage). Analysis by infrared spectroscopy and focused ion-beam sectioning confirmed incorporation of iron oxide nanoparticles into the microspheres and the prepared samples were shown to be responsive to an applied magnetic field. This study demonstrates a convenient method for the preparation of nanoparticle loaded microspheres, which could be used potentially as transverse relaxation contrast agents in magnetic resonance imaging, as well as for magnetically guided drug delivery.