超细水雾全尺寸灭火试验研究

采用超细水雾全淹没灭火装置在3m×3m×3m的全尺寸密闭空间内进行庚烷火灭火试验,从而验证超细水雾在较大密闭空间内灭庚烷火的适用性。试验采用200mL/min和500mL/min的超细水雾灭火装置同时施加超细水雾,试验火源分别使用40kW和120kW的庚烷火,产雾所用的水分别采用纯水和含碳酸氢钠的水溶液,通过四种不同工况验证超细水雾的灭火效果。试验结果表明,超细水雾可扑灭较大密闭空间内的庚烷火,NaHCO3能够显著增强超细水雾的灭火效果。     

房地产开发商在工程量清单招标时需注意的问题

通过市场调查,详细分析了建设单位在工程量清单招标中存在的对材料价格不确定、不重视市场价格因素等问题,并提出了具体的解决策略,以降低工程成本,实现建筑企业间的良性竞争。     

山西省古建筑消防安全工作存在的问题及对策

通过对专项治理发现的古建筑消防安全工作存在的问题的研究 ,提出了解决这些问题的建议     

Effect of Drying on Particle Size and Sensitivities of Nano hexahydro-l,3,5-trinitro-l,3,5-triazine

Nano hexahydro-l,3,5-trinitro-l,3,5-triazine （RDX） was prepared using a bi-directional rotation mill and dried under different conditions （liquid, temperature and drying）. It shows that the samples cake seriously and the particles grow up obviously by ordinary drying in different liquids at 70 ℃, which occurs again after vacuum drying. With the increase of temperature, the degrees of caking and aggregation are enhanced. Well dispersed sample maintaining constant particle size is extracted by supercritical drying, especially freeze drying. Furthermore, the me- chanical sensitivities of I-RDX, O-RDX and F-RDX, of which the average sizes are 88.03 μm, 15.32 μm and 0.16 μm, respectively, are evaluated. Compared with I-RDX, the friction, impact and shock sensitivities of O-RDX are slightly lower. However, the friction, impact and shock sensitivities of F-RDX are reduced by 30%, 99.0% and 59.9%, respectively.     

管井降水技术在多种含水介质基坑工程中的应用

结合蚌埠城市中心广场会展中心工程，介绍了管井降水技术在多种含水介质的复杂地质环境下的应用。     

Rapid Bonding of Ti3SiC2 and Ti3AlC2 by Pulsed Electrical Current Heating

Inspired by pressure resistance welding of metallic materials, herein we describe how two MAX phases—Ti₃SiC₂ and Ti₃AlC₂—were successfully joined by a rapid electric current heating method in a pulsed electric current sintering furnace. No welding agent was employed and the total processing time was less than 6 min. When the bulk temperature of the joint couple exceeded 1070°C, good joints, with shear strength above 50 MPa, were achieved in both homo‐ and heterojunction joints.     

Thermal degradation behavior and gas phase flame‐retardant mechanism of polylactide/PCPP blends

The thermal degradation behavior of the blend based on polylactide (PLA) and poly(1,2‐propanediol 2‐carboxyethyl phenyl phosphinate) (PCPP) was investigated by the thermogravimetric analysis (TGA). Thermal degradation activation energies (E_a) of neat PLA and PLA/15% PCPP blend were calculated via the Flynn–Wall–Ozawa method. The E_a of the blends increased with the addition of PCPP increasing when the conversion was higher than 10%. In addition, the appropriate conversion models for the thermal degradation process of PLA and PLA/15% PCPP were studied via the Criado method. At the same time, the main gaseous decomposition products of PLA and its blend were identified by TGA/infrared spectrometry (TGA–FTIR) analysis. And it revealed that the PCPP improved the flame‐retardant property of PLA via altering the release of the flammable gas and nonflammable gas. Moreover, the PCPP improved the flame‐retardant property of PLA by inhibiting exothermic oxidation reactions in the combustion, which was further proved by pyrolysis–gas chromatography–mass spectrometry analysis. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40480.     

The use of environmental scanning electron microscopy for imaging the microstructure of gels for profile control and water shutoff treatments

The use of gel systems as profile control and water shutoff agents has become a wide practice in recent years for oil recovery applications. But few systematic studies have been carried out on the microstructure of gels. In this study, environmental scanning electron microscopy (ESEM) was employed to investigate the microstructure of gels in their natural state. It was directly observed that a three‐dimensional network structure formed in chromium or zirconium crosslinked polymer gels is the same as organic/ inorganic crosslinked gels. However, there is a dense flat structure in phenol resin crosslinked polymer gels or phenolic resin gels. The differences between the microstructures can be attributed to the different crosslinking sites and crosslinking density, and this affect the gel's stability at reservoir temperatures. In addition, this paper also introduced the crosslinking mechanism and macro‐morphology of the bulk gels. It can contribute to a better understanding of the gel's microstructure. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39946.     

One-Pot Synthesis,Crystal Structure,and Thermal Decomposition Behavior of 1,1ʹ-Diamino-4,4ʹ,5,5ʹ-Tetranitro-2,2ʹ-Biimidazole

1,1?-Diamino-4,4?,5,5?-tetranitro-2,2?-biimidazole (DATNBI) was synthesized, by employing one-pot facile method, from 4,4?,5,5?-tetranitro-2,2?-biimidazole. The crystal structure was determined by X-ray diffraction for the first time. DATNBI crystallized in monoclinic system P2₁/c, with a crystal density of 1.934 g cm^?3 at 293(2) K and 2.019 g cm^?3 at 130(2) K, respectively. Its crystal parameters at 293 K are a = 4.8833(15) Å, b = 6.960(2) Å, c = 6.928(4) Å, α = γ = 90°, β = 93.418(6)°, V = 591.1(3) ?³, Z = 2, μ = 0.178 mm^?1, and F(000) = 348. The thermal stability and non-isothermal kinetics of DATNBI were studied by differential scanning calorimeter (DSC) with heating rates of 5, 10, 15, and 20 K min^?1. The apparent activation energy (E_a) at the first decomposition peak calculated by Kissinger, Ozawa, and Starink equations were 85.50, 89.67, and 86.10 kJ mol^?1, respectively. For the second peak, these were 116.49, 119.82, and 117.45 kJ mol^?1, respectively, with individual pre-exponential factors lnA = 18.40 s^?1 and lnA = 25.11 s^?1. The thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR) analysis of thermal decomposition products reveals that the main decomposition gas products are H₂O, N₂O, CO₂, and NO₂. Based on the new crystalline densities, the detonation velocity and pressure predicted by EXPLO5 are 9062 m s^?1 and 36.4 GPa, respectively.     

Dearomatization of Indole Derivatives via Palladium‐Catalyzed C?H Bond Functionalization of Pyrroles: Convenient Construction of Spiroindolenines

An intramolecular palladium(II)‐catalyzed dearomative arylation reaction of indoles via C H bond functionalization was developed, providing access to structurally novel spiroindolenines with moderate to good yields. A one‐pot process for the synthesis of spiroindoline derivatives was also realized.