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排序方式: 共有137条查询结果,搜索用时 156 毫秒
111.
Joseph A. Main George A. Gazonas 《International Journal of Solids and Structures》2008,45(7-8):2297-2321
Motivated by recent efforts to mitigate blast loading using energy-absorbing materials, this paper uses analytical and computational modeling to investigate the influence of mass distribution on the uniaxial crushing of cellular sandwich plates under air blast loading. In the analytical model, the cellular core is represented using a rigid, perfectly-plastic, locking idealization, as in previous studies, and the front and back faces are modeled as rigid, with pressure loading applied to the front face and the back-face unrestrained. This model is also applicable to the crushing of cellular media in “blast pendulum” experiments. Fluid–structure interaction effects are treated using a recent result that accounts for nonlinear compressibility effects for intense air blasts. Predictions of the analytical model show excellent agreement with explicit finite element computations, and the model is used to investigate the response of the system for all possible distributions of mass between the front and back faces and the cellular core. Increasing the mass fraction in the front face is found to increase the impulse required for complete crushing of the cellular core but also to produce undesirable increases in back-face accelerations. Optimal mass distributions for mitigating shock transmission through the sandwich plate are investigated by maximizing the impulse capacity while limiting the back-face accelerations to a specified level. 相似文献
112.
Russell M. Main David B. Cordes Aamod V. Desai Alexandra M. Z. Slawin Paul Wheatley A. Robert Armstrong Russell E. Morris 《Molecules (Basel, Switzerland)》2021,26(22)
The rapid growth in the field of metal-organic frameworks (MOFs) over recent years has highlighted their high potential in a variety of applications. For biological and environmental applications MOFs with low toxicity are vitally important to avoid any harmful effects. For this reason, Ca-based MOFs are highly desirable owing to their low cost and high biocompatibility. Useful Ca MOFs are still rare owing to the ionic character and large size of the Ca2+ ion tending to produce dense phases. Presented here is a novel Ca-based MOF containing 2,3-dihyrdoxyterephthalate (2,3-dhtp) linkers Ca(2,3-dhtp)(H2O) (SIMOF-4). The material undergoes a phase transformation on heating, which can be followed by variable temperature powder X-ray diffraction. The structure of the high temperature form was obtained using single-crystal X-ray diffraction. The electrochemical properties of SIMOF-4 were also investigated for use in a Na ion battery. 相似文献
113.
采用高分离度快速液相色谱(RRLC)测定牛黄解毒片中黄芩苷的含量。色谱柱为Zorbax XDB-C18(4.6×50mm,1.8μm),流动相为甲醇-水-磷酸(45∶55∶0.2),检测波长315nm,流速0.5mL.min-1,柱温为30℃。黄芩苷在0.15—1.35μg(r=0.9999)范围内峰面积与浓度呈良好的线性关系,加样回收率为100.41%,RSD=1.42%。采用高分离度快速液相色谱(RRLC)测定复方牛黄解毒片中黄芩苷的含量,缩短了保留时间,提高了效率,降低了成本。本方法简便、准确,结果稳定。 相似文献
114.
A four-hole pyramid probe has been calibrated for use in a short-duration transonic turbine cascade tunnel. The probe is used to create area traverse maps of total and static pressure, and pitch and yaw angles of the flow downstream of a transonic annular cascade. This data is unusual in that it was acquired in a short-duration (5 s of run time) annular cascade blowdown tunnel. A four-hole pyramid probe was used which has a 2.5 mm section head, and has the side faces inclined at 60° to the flow to improve transonic performance. The probe was calibrated in an ejector driven, perforated wall transonic tunnel over the Mach number range 0.5–1.2, with pitch angles from -20° to + 20° and yaw angles from-23° to +23°. A computer driven automatic traversing mechanism and data collection system was used to acquire a large probe calibration matrix (~ 10,000 readings) of non dimensional pitch, yaw, Mach number, and total pressure calibration coefficients. A novel method was used to transform the probe calibration matrix of the raw coefficients into a probe application matrix of the physical flow variables (pitch, yaw, Mach number etc.). The probe application matrix is then used as a fast look-up table to process probe results. With negligible loss of accuracy, this method is faster by two orders of magnitude than the alternative of global interpolation on the raw probe calibration matrix. The blowdown tunnel (mean nozzle guide vane blade ring diameter 1.1 m) creates engine representative Reynolds numbers, transonic Mach numbers and high levels (≈ 13%) of inlet turbulence intensity. Contours of experimental measurements at three different engine relevant conditions and two axial positions have been obtained. An analysis of the data is presented which includes a necessary correction for the finite velocity of the probe. Such a correction is non trivial for the case of fast moving probes in compressible flow. 相似文献
115.
116.
Detection of bacteria using antimicrobial polymer derived via ring-opening metathesis (romp) pathway
N. Ceren SÜER Tülin ARASOLU Hüsnü CANKURTARAN Mustafa OKUTAN Markus GALLEI Tarik EREN 《Turkish Journal of Chemistry》2021,45(4):986
There is growing interest in the detection of bacteria in consumables, for example, in the food and water sectors. In this study, the aim was to produce a polymer-based bacteria biosensor via ROMP (ring opening metathesis polymerization). In the first part of the study, block and random copolymers were synthesized, and their biocidal activities were tested on the glass surface. Interdigitated electrode arrays coated with the polymers possessing the highest activity were used to screen the affinity towards different bacterial strains by monitoring impedance variations in real-time. The polymer-coated electrode could detect gram-positive and gram-negative bacteria strains at a concentration of 107 cfu/mL. The results show that ROMP-based polymer offers bacterial detection and can be used in developing biosensor devices for efficiently detecting pathogenic bacteria. 相似文献
117.
Ceren ATLA DNER Ceren G
KALP Bengü GETREN Atila YILDIZ Nuray YILDIZ 《Turkish Journal of Chemistry》2021,45(4):1248
Usnic acid (UA) was extracted from Usnea longissima (L.) Ach. in supercritical carbon dioxide (SC-CO2) medium. The selected process parameters were extraction temperature (35–45 °C), amount of co-solvent (0%–5%) and extraction time (5–9 h). These parameters were applied to Box-Behnken design (BBD) belonging to response surface methodology (RSM) to determine optimum process parameters for the highest amount of UA in the extract. g UA/100g lichen, extraction yield % and UA content values were calculated in the range of 0.045–0.317, 2.77–5.4 and 71%–82% in different experimental conditions, respectively. The optimum conditions were predicted as 42 °C, 4.3% (ethanol) and 7.48 h. It was determined that the predicted and experimental values of g UA/100g lichen were compatible, and the suggested model was valid. 相似文献
118.
R. J. A. Hill S. T. Stoddart P. C. Main L. Eaves K. A. Benedict M. Henini 《Physica E: Low-dimensional Systems and Nanostructures》2000,6(1-4)
We present a novel technique for measuring the lifetime of quasiparticle excitations of a 2DES by investigating the tunnelling into a quantum dot from a 2DES over an extended range of energy from the Fermi energy to the sub-band edge. We find that the lifetime τqp, of a quasihole excitation, caused by removing an electron from a 2DES state with energy below the Fermi energy EF, has the form τqp=α/, where α is a constant of order unity. 相似文献
119.
120.