Effect of externally injected radiation on amplified spontaneous emission in CO

The effect of externally injected radiation on the two-photon laser-induced amplified spontaneous emission (TP-LIASE) is reported. The wave generated via the same LIASE process in a seeder cell acts as a seeder field for the inverted medium created in a main cell. A nearly tenfold gain is achieved in the B¹ Σ ⁺ ?A¹ Π (0, 3) transition of the CO molecule. We demonstrate that the single rotational transition in the B¹ Σ ⁺ ?A¹ Π (0, 4) band is selectively amplified by injection of laser radiation. This pump and seed arrangement facilitates detection of molecular spectra by simply tuning the seed-laser frequency. The polarization effect of the input laser radiation is briefly discussed. Received: 9 June 2000 / Revised version: 2 October 2000 / Published online: 21 February 2001     

两不同奇相干态组成的第种四态叠加多模叠加态光场的等阶N次方Y压缩

本文构造了由两不同奇相干态组成的第Ⅲ种四态叠加多模叠加态光场|Ψ_o⁽⁴⁾,Ⅲ>_q.利用新近建立的多模压缩态理论,详细研究了态|Ψ_o⁽⁴⁾,Ⅲ>_q的广义非线性等阶N次方Y压缩特性,结果发现由不呈现等阶高阶压缩效应的两奇相干态线性叠加组成的新量子光场态|Ψ_o⁽⁴⁾,Ⅲ>_q呈现出许多奇异物理现象:1)当压缩阶数N=4m(m=1,2,3,…,…)时,态|Ψ_o⁽⁴⁾,Ⅲ>_q始终恒处于等阶N-Y最小测不准态;2)当压缩阶数N=4m-2(m=1,2,3,…,…)时,在一定条件下,态|Ψ_o⁽⁴⁾,Ⅲ>_q的某一正交分量处于等阶N-Y最小测不准态时,另一正交分量则始终既不处于等阶N-Y最小测不准态,也不呈现等阶N次方Y压缩效应,这种现象称为“半相干态”效应;在另外一些条件下,态|Ψ_o⁽⁴⁾,Ⅲ>_q的两正交分量可分别呈现出等阶N次方Y压缩效应,其压缩特性具有周期性变化的、互补对称的关系.3)当压缩阶数N为奇数时,态|Ψ_o⁽⁴⁾,Ⅲ>_q始终不会呈现等阶N次方Y压缩效应,也不处于等阶N-Y最小测不准态,但在一定条件下可呈现“半相干态”效应.     

半平面上的无限级随机Dirichlet级数的值分布

本文通过 Dirichlet级数增长性研究结果改进 ,以及对独立随机变量列 { Zn} ,在条件 EZn=0 , 正数α>0 ,使得 ,0 相似文献   

Polynomial Vector Fields with Prescribed Algebraic Limit Cycles

For each non-singular real algebraic curve f = 0 of degree m we exhibit an explicit vector field of degree m which has precisely the bounded components of f = 0 as limit cycles. The degree of the system is optimal for a generic class of algebraic curves and improves the significantly the bounds given by Winkel.     

中国21世纪若干重大工程地质与环境问题

21世纪中国的大规模的国家建设不可避免地导致大量的工程地质与环境问题。 2 1世纪中国西部高山峡谷地区主要工程地质问题有: 构造活动带岩土体动力稳定性, 高地应力下岩体应变储能与岩体性质, 高陡边坡的变形及尺寸效应和动力稳定性, 深埋长大隧洞的地温与地压, 深埋隧洞岩体结构探测与施工地质超前预报, 大跨度复杂洞群变形与稳定性的群洞效应, 冻土的冻融变形、稳定性及其处理技术, 可溶岩岩溶规律与岩体利用问题, 河床深厚覆盖层的处理与利用等问题; 中国东部及沿海地区工程地质问题包括: 高速交通网建设中软土地基变形与稳定性及处理技术, 深井采矿中软岩巷道大变形与处理技术, 深厚松散堆积层上大型桥梁桥基变形与稳定性, 海底隧道围岩工程地质与水文地质问题, 城市多层地下空间开发中的工程地质问题等; 此外, 水土流失与北方大规模荒漠化问题, 黄河下游地上悬河与长江下游塌岸和堤防稳定性问题, 黄河断流引起的下游地区环境问题, 我国北方干旱地区水资源长期匮乏问题, 城市化中的环境破坏与污染控制等问题, 将是中国 2 1世纪突出的环境问题。中国工程地质工作者应当在结构土力学与岩体结构力学、工程地质学的基本理论与工程地质动力学、人 地相互作用机制与环境工程地质学、地质工程理论与方法。     

Integration of multi access edge computing with unmanned aerial vehicles: Current techniques,open issues and research directions

During the last decade, research and development in the field of multi access edge computing (MEC) has rapidly risen to prominence. One of the factors propelling MEC’s evolution is the ability to deploy edge servers capable of providing both communication and computational services in close proximity to the mobile user terminal. MEC has been regarded as a potentially transformative technique for fifth-generation (5G) and beyond 5G (B5G) wireless communication systems, as well as a possible complement to traditional cloud computing. Additionally, unmanned aerial vehicles (UAVs) integrated with MEC will play a critical role by introducing an additional mobility based computational layer to provide more secure, efficient and faster services. UAV enabled MEC offers seamless connectivity, fulfilling the promise of 5G’s ubiquitous connectivity. Due to the enormous interest in UAV enabled MEC, there has been a tremendous increase in the number of published research articles in this domain; however, the research area still lacks a systematic study and categorization. We present a systematic literature review (SLR) on UAV enabled MEC, examining and analyzing data on the current state of the art using preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. To streamline our assessment, this study analyzes several research papers carefully selected through a multi-stage process satisfying the eligibility criteria defined in the paper. One of the SLR’s primary contributions is to broadly classify the research in the UAV enabled MEC domain into different categories including energy efficiency, resource allocation, security, architecture, and latency. We have identified key findings, technology, and pros and cons for the selected articles under each category. Additionally, we discuss the key open issues related to scalability and fairness, resource allocation and offloading optimization, service delivery with a focus on quality of experience (QoE) and quality of service (QoS), and standardization. Finally, we discuss several future research directions that would address the aforementioned issues and emerging use cases for UAV enabled MEC.     

Finite element analysis of edge lamination during hot rolling process of aluminium alloy

Summary The rigid-plastic finite element method is applied to the analysis of the three-dimensional deformation behaviour, in particular the forming of edge lamination during the multi-pass hot roughing process of aluminium. the calculation is carried out for various rolling conditions and reduction schedules, and their influence on the edge lamination is examined. The results suggest that the crop loss due to the edge lamination can be reduced by increasing the roll diameter, the reduction per pass and the initial width of the slab.     

19世纪浙江海区历史海图初考

历史海图可以成为一些相关学科理论研究和工程应用的基础史料.本文所讨论的内容则可以成为比较系统地认识这些基础史料的索引.19 世纪浙江海区历史海图约 50 幅.本文大致按年代顺序论述了这些历史海图的历史沿革、时空分布、基本特征和初步评估等     

The Cambridge Mathematical Journal and its descendants: the linchpin of a research community in the early and mid-Victorian Age

The Cambridge Mathematical Journal and its successors, the Cambridge and Dublin Mathematical Journal, and the Quarterly Journal of Pure and Applied Mathematics, were a vital link in the establishment of a research ethos in British mathematics in the period 1837–1870. From the beginning, the tension between academic objectives and economic viability shaped the often precarious existence of this line of communication between practitioners. Utilizing archival material, this paper presents episodes in the setting up and maintenance of these journals during their formative years.