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钢纤维混凝土(Steel fiber reinforced concrete,SFRC)具有优异的延性、韧性及能量吸收能力,被广泛应用于各类防护结构。K&C模型已成为研究普通混凝土构件动力响应的常用材料模型,但仍无法准确表征SFRC的动力特性。为了提高K&C模型在冲击及爆炸荷载作用下预测SFRC板动力响应的能力,对K&C模型进行了改进:基于大量三轴压缩实验数据,建立了新的失效强度面参数模型;采用反复试验法,建立了新的损伤演化模型,并校准了拉、压损伤参数;基于大量高应变率下SFRC的单轴压缩实验数据,建立了新的受压动力增强因子模型。通过LS-DYNA显式有限元动力分析软件模拟了SFRC板的动力响应,模拟结果验证了上述改进的有效性与可靠性。 相似文献
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测定了25℃下,添加不同浓度的EDTA后,不同过饱和比下ZTS溶液的诱导期,研究了掺杂浓度及过饱和比对ZTS溶液成核的影响.研究显示,当溶液处于较高过饱和比时(S>1.13),均匀成核占主导;而在较低过饱和比时(S< 1.11),则以非均匀成核为主.利用经典成核理论对实验所得数据进行分析,计算得到了界面张力、临界核形成功、临界核半径等成核特性,发现了溶液过饱和比及掺杂浓度对成核速度的影响,解释了添加EDTA能提高溶液稳定性的原因.利用界面张力的值计算得到了表面熵因子. 相似文献
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首先测量了KDP溶液的亚稳区,并据此开展“点籽晶”KDP晶体快速生长实验.在实验中采用两种晶体运动方法-“二维平动法”和“旋转法”来生长晶体,分别得到尺寸为55 mm×55 mm×48 mm和60 mm×60 mm×45 mm的晶体.将两种运动方式生长的晶体通过透过光谱,锥光干涉图以及化学腐蚀方式进行质量对比.结果表明,两种方式生长的晶体透过光谱没有太大区别,都具有较高的透过率,但“二维平动法”生长的晶体具有较好光学均匀性,位错密度明显降低.说明“二维平动法”生长晶体的方式能够减少晶体内部缺陷,提高晶体质量. 相似文献
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Control of spiral waves and turbulent states in a cardiac model by travelling—wave perturbations 总被引:3,自引:0,他引:3 下载免费PDF全文
We propose a travelling-wave perturbation method to control the spatiotemporal dynamics in a cardiac model.It is numerically demonstrated that the method can successfully suppress the wave instability(alternans in action potential duration) in the one-dimensional case and converty spiral waves and turbulent states to the normal travelling wave states in the two-dimensional case.An experimental scheme is suggested which may provide a new design for a cardiac defibrillator. 相似文献
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Coherent excitons at different orientation arrangements of local transition dipole moments in circular light-harvesting complexes 下载免费PDF全文
The coherent exciton plays an important role in the photosynthetic
primary process, and its functions are deeply dependent on the
orientation arrangements of local transition dipole moments (TDMs).
We theoretically and systematically study the physical property of
the coherent exciton at different orientation arrangements of the
local TDMs in circular light-harvesting (LH) complexes. Especially,
if the orientation arrangements are different, the delocalized TDMs
of the coherent excitons and the energy locations of the optically
active coherent excitons (OACEs) can be obviously different, and
then there are more manners to capture, store and transfer light
energy in and between LH complexes. Similarly, if the orientation
arrangements are altered, light absorption and radiative intensities
can be converted fully between the OACEs in the upper and lower
coherent exciton bands, and then the blue and red shifts of the
absorption and radiative bands of the pigment molecules can occur
simultaneously at some orientation arrangements. If the systems are
in the vicinities of the critical orientation arrangements, the weak
static disorder or small thermal excitation can destroy the coherent
electronic excitations, and then the coherent exciton cannot exist
any more. 相似文献
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