红光InAlAs量子点的结构和光学性质

利用ＭＢＥ方法在（００１）衬底上成功地生长密度大、尺寸小、发红光的ＩｎＡｌＡｓ／ＡｌＧａＡｓ量子点结构。通过原子力显微镜观察表明,ＩｎＡｌＡｓ量子的密度和大小都随覆盖厚度的增加而增大;发现Ａｌ原子的表面迁移率决定ＩｎＡｌＡｓ量子点的形貌,光荧光谱证实了量子点的发光峰值在红光范围,并结合形貌的统计得到了量子点的发光峰展宽主要昌受量子点的横向尺寸影响。     

Measurement of Titanium and Manganese K -shell Ionization Cross Sections by Electron Impact

报道了电子引起的钛、锰原子的Ｋ壳层电离截面实验值。实验中,采用了薄靶厚衬底技术,并将衬底中反射的电子对测量值的影响进行了修正。实验结果与其他文献报道的测量结果相吻合。最后,还将实验结果与Ｃａｓｎａｔｉ等人的经验公式进行了比较。     

La(BO_2)_3基质中Eu~(3+)的发光性质与晶体结构的关系

采用高温固相反应合成了 (La1-xEux) (BO2 ) 3 ,利用X射线粉末衍射方法确定其晶体结构 ,利用红外光谱探讨了 [BO3 ]单元的聚合情况。根据 (La1-xEux) (BO2 ) 3 所属空间群中等效点系的对称性分析及Eu3 + 的荧光光谱 ,详细地探讨了Eu3 + 的发光性质与其所处格位点对称性的关系。La(BO2 ) 3 ∶Eu3 + 体系中 ,Eu3 + 出现较强的5D0 →7F1磁偶极跃迁 ,因而Eu3 + 主要占据点对称性为Ci 的格位 ,出现的其它跃迁是部分Eu3 + 占据偏离Ci 的格位 ,而并非占据C2 或C1格位 ,另外 ,5D0 →7F4 跃迁发射很强 ,其原因尚不清楚。选择适当的助熔剂可以提高样品的结晶程度 ,有利于Eu3 + 占据严格的Ci 格位 ,增强材料的发光性能。     

Set to set broadcasting in communication networks

Suppose G = (V,E) is a graph whose vertices represent people and edges represent telephone lines between pairs of people. Each person knows a unique message and is ignorant of the messages of other people at the beginning. These messages are then spread by telephone calls. In each call, two people exchange all information they have so far in exactly one unit of time. Suppose A and B are two nonempty subsets of V. The main purpose of this paper is to study the minimum number b(A,B,G) of telephone calls by which A broadcasts to B; and the minimum time t(A,B,G) such that A broadcasts to B. In particular, we give an exact formula for b(A,B,K_n) and linear-time algorithms for computing b(A,B,T) and t(A,B,T) of a tree T.     

一类广义幂零群

This paper considers such a group G which possesses nontrivial proper subgroups H 1 ,H 2 such that any proper subgroup of G not contained in H 1 ∪ H 2 is p-closed and obtains that if G is soluble,then the number of prime divisors contained in ｜G｜ is 2,3 or 4;if not,then it has a form x N where N/Φ（N） is a non-abelian simple group.Then the structure of such a group is determined for p = 2,H 1 = H 2 under some conditions.     

Revised multi-choice goal programming for multi-period,multi-stage inventory controlled supply chain model with popup stores in Guerrilla marketing

In this paper, we consider a supply chain network design problem with popup stores which can be opened for a few weeks or months before closing seasonally in a marketplace. The proposed model is multi-period and multi-stage with multi-choice goals under inventory management constraints and formulated by 0–1 mixed integer linear programming. The design tasks of the problem involve the choice of the popup stores to be opened and the distribution network design to satisfy the demand with three multi-choice goals. The first goal is minimization of the sum of transportation costs in all stages; the second is to minimization of set up costs of popup stores; and the third goal is minimization of inventory holding and backordering costs. Revised multi-choice goal programming approach is applied to solve this mixed integer linear programming model. Also, we provide a real-world industrial case to demonstrate how the proposed model works.     

Theoretical models for the extracavity Raman laser with crystalline Raman medium

The rate equation model of an extracavity Raman laser is deduced for the first time to the best knowledge of the authors. The normalized radiation transfer equations of the extracavity Raman laser are given. The normalized radiation transfer equations and rate equations were solved numerically to find the optimum reflectivity of the output coupler to realize the maximum conversion efficiency at the first Stokes for both the single and double-pass pumping configurations. Also, the pulse duration of the first Stokes was investigated numerically. The rate equations are verified to be a good approximation to the radiation transfer equations for the regime of low Raman gain and long pump pulse duration. Furthermore, it is found that the optimum reflectivity of the first Stokes and the second Stokes threshold are influenced significantly by the minor feedback of the resonator mirror at the second Stokes. PACS 42.55 42.55.Ye; 42.65 42.65.Dr; 02.60 02.60.Lj; 63.20 63.20.-e     

V3+:YAG晶体的生长、色心与光谱性能研究

采用石墨电阻加热的温梯法生长了V:YAG晶体,晶体的不同部位呈现两种不同的颜色:浅绿色和黄褐色.通过对比分析不同颜色V:YAG晶体的室温吸收光谱,推断出石墨发热体高温下扩散出来的C可以起到还原作用,提高晶体中V3+tetra离子的浓度,同时诱导了F心的形成.在1300℃下,对不同颜色的V:YAG晶体进行真空退火处理,发现处于八面体格位中的V3+离子在热激发作用下与近邻的四面体格位Al3+离子存在置换反应,由此产生一定浓度的四面体格位V3+离子.同时,F心在退火过程中被完全消除,释放出来的自由电子被高价态的V离子俘获,可以进一步提高晶体中四面体格位V3+离子的浓度.     

Quantitative determination of material viscoelasticity using a piezoelectric cantilever bimorph beam

The objective of this paper is to formulate the governing equation of a cantilever bimorph beam associated with a tip mass in contact with a viscoelastic material, which is modeled by a stiffness and a damper in parallel. From the eigenvalue problem, we can obtain the resonant frequencies as functions of the tip mass and material stiffness. The relation between the spectrum and material damping is established by the half-power bandwidth. It is found that the resonant frequencies increase as the material stiffness increases or the tip mass decreases, and the spectrum decreases by increasing the damping. From the analytic results, a cantilever could provide a technique to assess material viscoelasticity by simple measurements of the resonant frequency and the spectrum. Since the cantilever's behavior scales with its geometry, the device can be designed specifically for mechanical measurement of a microscopic system such as living cells and biomaterials.     

Transflective liquid-crystal display using low-twisted vertically aligned mode

We present the design of a transflective and low-power LCD using a low-twist vertically aligned liquid crystal (LC) cell, achieved by blending a chiral additive with a patterned reflector in a single-domain configuration. Unlike the conventional single-domain transflective LCD, in which it is possible to optimize only one of the transmissive and reflective regions, the device suggests that it is possible to optimize both the transmission and reflection design to obtain favorable results in both reflective and transmissive light conditions by optimizing the chiral pitch and twist angle. From the parameter space diagram (PSD) method, which does not include the information on chiral pitch and the nonuniform LC director tilt angle, optimization focused on the transmissive region is performed. By analyzing the relation between the transmittance and the chiral pitch under the applied voltage, the optimized twist angle and chiral pitch are proposed. It is described that the optimized twist angle is also available for the reflective region by the dynamic PSD method by considering the average tilt angle under applied voltage.