水下爆炸中气泡射流壁压特性实验研究

水下爆炸气泡射流载荷是中近场水下爆炸壁压载荷的重要组成部分, 将水下爆炸气泡射流简化为一段高速水柱来研究水下爆炸气泡射流载荷特性是研究水下爆炸气泡射流载荷的主要手段。本文基于腔内爆炸提出了一种新的高速水射流实验方法，并给出了实验装置设计、实验方法以及实验系统。基于实验系统，开展了不同工况下高速水射流的实验研究，研究了腔口位置、腔深对水射流形态的影响，并对水射流的形态形成因素进行了分析。使用压电型壁压传感器测得了水射流冲击壁压，给出了水射流冲击壁压的特性及其特点。实验结果表明:腔口位置与腔深是影响水射流端面形态的重要因素；生成的高速水射流冲击壁压峰值满足水锤理论。基于腔内爆炸的高速水射流实验方法能够应用于包括水下爆炸气泡射流在内的高速水射流形态、壁压特性的研究。     

三级复叠式制冷系统性能的实验研究

实验系统为三级复叠制冷循环,制冷系统制冷剂为R404A/R23/R14,最低温度可达到-110℃以下。实验时测量系统运行的温度、压力以及压缩机的压比、耗功等参数。结果表明:库温从-60℃降低到-110℃的过程中,三级复叠式制冷循环制冷量先升高后降低,在-80℃左右时达到最大值,并且在整个降温降温过程中,压缩机的耗功一直减小;由三台压缩机的吸、排气压力变化图以及压比变化图和排气温度变化图分析可知,系统有不匹配的地方,还需进一步改进。     

High-pressure effect on inverse spinel LiCuVO4:X-ray diffraction and Raman scattering

The effect of external quasi-hydrostatic pressure on the inverse spinel structure of LiCuVO 4 was studied in this paper. High-pressure synchrotron X-ray diffraction and Raman spectroscopy measurements were carried out at room temperature up to 35.7 and 40.3 GPa, respectively. At a pressure of about 20 GPa, both Raman spectra and X-ray diffraction results indicate that LiCuVO4 was transformed into a monoclinic phase, which remained stable up to at least 35.7 GPa. Upon release of pressure, the high-pressure phase returned to the initial phase. The pressure dependence of the volume of low pressure orthorhombic phase and high-pressure monoclinic phase were described by a second-order Birch-Murnaghan equation of state, which yielded bulk modulus values of B 0 = 197(5) and 232(8) GPa, respectively. The results support the empirical suggestion that the oxide spinels have similar bulk modulus around 200 GPa.     

Influence of GaAsP Insertion Layers on Performance of InGaAsP/InGaP/A1GaAs Quantum-Well Laser

We report on the use of very thin GaAsP insertion layers to improve the performance of an In GaAsP/InGaP/AIGaAs single quantum-well laser structure grown by metal organic chemical vapour deposition. Compared to the noninsertion structure, the full width at half maximum of photoluminescence spectrum of the insertion structure measured at room temperature is decreased from 47 to 38 nm indicating sharper interfaces. X-ray diffraction shows that the GaAsP insertion layers between AIGaAs and InGaP compensates for the compressive strain to improve the total interface. The laser performance of the insertion structure is significantly improved as compared with the counterpart without the insertion layers. The threshold current is decreased from 560 to 450 mA while the slope efficiency is increased from 0.61 to 0.7W/A and the output power is increased from 370 to 940mW. The slope efficiency improved is very high for the devices without coated facets. The improved laser performance is attributed to the suppression of indium carry-over due to the use of the GaAsP insertion layers.     

软代数的同余理想

本文以软代数Ｆ的真积分解为工具，得到的主要结果是，如果软代数Ｆ的每信满足条件Ｉ∩Ｉ’＝Φ的理想Ｉ都是同余理想。则Ｆ是既约软代数，在既约的情况下，给出了软代数Ｆ的每个满足条件Ｉ∩Ｉ‘＝Φ的理想Ｉ都是同余理想的一个充分条件。从而初步解决了文「１」的结尾提出的一个问题。     

综合题新编选登

题 8 8 　已知数列 {an},{bn}且a1=b1=1,an + 1=an+ 3bn,bn + 1=an+bn,记xn =anbn.1)求xn + 1与xn 的关系式 .2 )判断数列 {|xn - 3| }的单调性 .3)求数列 {xn}的极限值 .4 )求证 :|x1- 3| + |x2 - 3| +… +|xn - 3| <3+ 1.解　 1)xn + 1=an + 1bn + 1=an+ 3bnan +bn=anbn+ 3anbn+ 1=xn + 3xn + 1,其中x1=a1b1=1.2 )xn + 1- 3=xn+ 3xn+ 1- 3=( 1- 3) (xn- 3)1+xn.∵x1=1,xn + 1=xn + 3xn + 1,∴xn >0 .∴ |xn + 1- 3| =3- 11+xn|xn - 3|<( 3- 1) |xn - 3|<|xn - 3| .　 {|xn - 3| }为递减数列 .3)由 2 )知 :n >1时 ,0 <|xn - 3| <( 3- 1) |x…     

中等质量核激发态奇异核结构的研究

在球形非线性相对论平均场(RMF)的理论框架下, 研究了β稳定线附近中等质量(z=20—50)奇A核在激发态下存在的晕或皮结构, 提取了价核子与核芯均方根半径的比值(R_vc), 并结合单中子或质子的分离能(Sn(p)), 讨论了具有晕或皮结构的激发态所呈现出来的带状分布, 说明了壳层结构与离心势垒对激发态晕或皮结构形成的重要影响.