大吨位自卸车引人瞩目

除了装载机在此次展会中相互争锋夺人眼球外,多家企业展出的矿用自卸车也吸引了众多关注。柳工展出本次展会最大的矿用自卸车SGE240,240吨级电传动矿用自卸车．     

强震再次袭川 工程机械全力以赴

五年前的创痍尚在平复,人们心中的伤口还未愈合。我们又不得不面对新的灾难:北京时间2013年4月20日8时02分,四川省雅安市芦山县发生7.0级地震,震源深度13公里,震中距成都约100公里。灾难再次突袭而至,灾情的严重再次超出我们的想象和预料,震中芦山县龙门乡99%以上房屋垮塌,那满目疮痍、废墟碎片和医院里人满为患的受伤同胞再次濡湿了我们的双眼;震后雅安仍未平静,余震不断发生,大地     

钢纤维活性粉末混凝土力学性能试验研究

通过对掺入钢纤维的活性粉末混凝土不同尺寸试件,以及在相同尺寸前提下有无掺入钢纤维的试件进行了抗压强度和抗折强度等力学性能试验研究,探讨了尺寸效应以及钢纤维对试件抗压、抗折强度的影响,在对掺入钢纤维混凝土试件进行弹性模量试验的基础上,得出其与抗压强度的关系。结果表明,尺寸效应对活性粉末混凝土的抗压强度影响较大,对抗折强度影响较小;而钢纤维的掺入能较大地提高活性粉末混凝土的抗折强度,改善其脆性大的性质。     

盐城市体育馆

现代化的综合性体育馆要满足专业性强、布局紧凑、功能多样、节能高效、以馆养馆等多项要求。江苏省盐城市体育馆是第十届全运会的比赛馆之一,赛时使用和赛后利用的兼顾、追求专业性与综合性的统一,是该馆建筑设计的重要内容。     

Surface and chemical diffusion effects of nanowire electrodes in lithium-ion batteries

Science China Technological Sciences - Nanostructured electrodes with surface effect show a distinct advantage in prolonging the lifetime of lithium-ion (Li-ion) battery. In order to characterize...     

Characteristics and applications of interplanetary coronal mass ejection composition

Science China Technological Sciences - In situ measurements of interplanetary coronal mass ejection (ICME) composition, including elemental abundances and charge states of heavy ions, open a new...     

Sintering Behavior and Dielectric Properties of Ultra‐Low Temperature Fired Silver Molybdate Ceramics

Ag₂MoO₄ ceramic was prepared by using the solid‐state reaction method, which could be sintered at 450°C for 2 h, having a relative permittivity of 8.08, a Qf value of 17 000 GHz, and a temperature coefficient of resonance frequency about ?133 ppm/°C. Ag₂MoO₄ ceramic was chemically compatible with silver but reacted seriously with aluminum to form (Ag_0.5Al_0.5)MoO₄ during the sintering. The fitting of infrared spectra and the Shannon's additive rule were employed to study intrinsic dielectric behaviors of the ceramics at microwave region. Ionic displacive polarization and the electronic polarization contributed almost equally to the dielectric permittivity of the ceramic at microwave region. The Ag₂MoO₄ ceramics could be a good candidate for ultra‐low temperature co‐fired microwave devices.     

A New Ferroelectric Phase of YMnO3 Induced by Oxygen‐Vacancy Ordering

Manganese oxides are good candidates of strongly correlated electron materials due to the uniqueness of electronic structure of manganese and the mobility of oxygen among lattice sites under external impacts. Here, we used electron beam as the excitation source to explore the structural evolution of YMnO₃ and identified a new phase under the radiation of electron beam in the transmission electron microscope. Analyses of the electron energy‐loss spectra reveal that this phase originates from ordered oxygen vacancy. We applied the first principles calculation to pick out the optimized stable structure with a lower polarization, and verified its correctness by electron diffraction and image simulations. Analyses of density of states indicate that weak Y–O covalence is favorable for the existence of ferroelectricity, supporting the electrostatic nature of ferroelectricity in the YMnO₃.     

压力指标法测定顺层钻孔有效抽放半径研究

为了测定申家庄煤矿顺层钻孔在合理抽采时间内的有效抽放半径,将瓦斯压力作为测定考察指标,利用灰色关联度分析验证有效压力降低钻孔,并利用曲线拟合抽放半径与抽放时间的关系。结果表明:当抽放钻孔为Ф94 mm时,合理抽放时间为60 d的有效抽放半径为5.5 m。     

水对阻燃高回弹聚氨酯泡沫塑料性能的影响

探讨了水与多元醇的质量比对阻燃高回弹聚氨酯泡沫塑料的反应活性、泡孔结构及制品性能的影响。结果表明:随着水与多元醇的质量比增大,制品的乳白、到顶和上升时间均呈下降趋势,泡孔孔径逐渐变小,制品的玻璃化转变温度上升,制品的拉伸强度逐渐上升,断裂伸长率逐渐降低,制品的氧指数从25.0%降低到22.5%。