A discrete-time retrial queueing model with one server

This paper presents a one-server queueing model with retrials in discrete-time. The number of primary jobs arriving in a time slot follows a general probability distribution and the different numbers of primary arrivals in consecutive time slots are mutually independent. Each job requires from the server a generally distributed number of slots for its service, and the service times of the different jobs are independent. Jobs arriving in a slot can start their service only at the beginning of the next slot. When upon arrival jobs find the server busy all incoming jobs are sent into orbit. When upon arrival in a slot jobs find the server idle, then one of the incoming jobs (randomly chosen) in that slot starts its service at the beginning of the next slot, whereas the other incoming jobs in that slot, if any, are sent into orbit. During each slot jobs in the orbit try to re-enter the system individually, independent of each other, with a given retrial probability.     

近2000年来太白山高山带不同海拔植被对气候变化的响应

根据西佛爷池(海拔3410 m)剖面的有机地球化学指标, 重建太白山高山带过去2000年的气候变化。对采自该剖面的样品进行孢粉分析, 并结合太白山跑马梁(海拔3556 m)、三清池(海拔3080 m)和芳香寺(海拔3000 m)剖面的孢粉数据, 进行聚类分析, 探讨高山带不同海拔植被对气候变化响应规律。结果表明, 不同海拔植被对相对冷干气候的响应有更好的一致性, 且林线过渡带内这种一致性更明显。随着现代升温期的到来, 植被对气候的响应主要受高程影响。研究结果可为认识晚全新世以来高山环境系统的气候?植被耦合关系提供一定的参考。     

杭州湾南岸慈溪地区晚第四纪沉积与古环境演化

杭州湾作为我国大陆沿海地区第四系厚度较大的沉积区之一,历来是我国地学、生物学和气候学研究的重点区域;但其南岸研究比较薄弱。在对杭州湾南岸第四系BZK1钻孔岩芯沉积物特征、地质年代、孢粉、有孔虫和介形类分析基础上,探讨了杭州湾南岸第四纪地层对比、古环境演化和海平面变化特征。钻孔揭示全新世沉积始于孔深22.00 m(约10.77 ka B P.),其下至孔深44.60 m为晚更新世地层,全新世沉积速率大于晚更新世。研究表明:古环境变化可划分为4个阶段:29.6~10.8 ka B P.晚更新世时期,以针叶、阔叶混交林为主,为气候温暖较湿的滨海河口湾半咸水环境;10.8~9.5 ka B P.早全新世早期,以针叶与常绿阔叶林为主,推测属亚热带温暖湿润气候下的潮上带湖沼环境;9.5~5.9 ka B P.全新世早中期,以常绿阔叶与针叶林为主,气候温和较湿,受海水波及;5.9~0.5 ka B.P.全新世中后期,以常绿阔叶与针叶林为主,属滨海-内陆架环境,该阶段后期海水已退出本区,气候由温暖湿润渐渐转凉。结果显示杭州湾南岸气候-环境-海平面-沉积速率之间具有较好的对应。上述研究可丰富杭州湾南岸第四纪地层学、环境地质学研究内容,为邻区晚更新世生物地层对比以及古植被和古环境分析提供证据。     

Scheduling jobs with release times preemptively on a single machine to minimize the number of late jobs

We give a direct combinatorial O(n³logn) algorithm for minimizing the number of late jobs on a single machine when jobs have release times and preemptions are allowed. Our algorithm improves the earlier O(n⁵) and O(n⁴) dynamic programming algorithms for this problem.     

New highly fluorinated phenazine derivatives: Correlation between crystal structure and NMR spectroscopy

New highly fluorinated derivatives of phenazine which are difficult to obtain in other ways, namely 1,2,2,3,4-pentafluoro-10-(2,3,4,5,6-pentafluorophenyl)-2,10-dihydrophenazine (2) and its hydrolyzed product 1,3,4-trifluoro-10-(2,3,4,5,6-pentafluorophenyl)-2(10H)-phenazinone (3), were both synthesized and characterized by means of single-crystal X-ray analysis and ¹H, ¹⁹F NMR spectroscopy. Correlation between the results of X-ray analysis and NMR spectroscopy is established. The formation mechanism of 2 involving oxidation of a cobalt complex bearing two noninnocent o-benzosemiquinonediiminato(1-) ligands is proposed.     

中上扬子晚奥陶世赫南特期岩相古地理

晚奥陶世赫南特期发生了全球性的气候变冷事件.中上扬子地区典型沉积为观音桥组,富产全球广泛分布的赫南特动物群,对应冰盖扩张引起的全球海平面下降阶段.根据岩性、沉积构造、生物组合及其保存状态,赫南特阶划分出潮坪相及浅海陆棚相.湖坪相主要沉积观音桥组炭泥质灰岩、钙质泥岩,底栖生物繁盛.浅海陆棚相主要沉积五峰组上部Normal...     

清末守旧派的科举情结

清朝末年的守旧派视奔涌而来的西方文化为流毒，认为其将造成人心风俗的变异。为抵制西方文化的渗透，维护儒家思想一统天下的局面，挽救濒临坍塌的封建道统，守旧派在言辞上处处维护科举制度，行动上严把科举入仕之关。然而，由于时势变化，守旧派固守传统的举措却并未能达到他们所期望的效果。     

长江三角洲南翼晚更新世古土壤及其成土环境

长江三角洲南翼全新统下伏的硬粘土层具有粘粒胶膜、土膜结构体、裂隙和微裂隙、植物根系和植物碎屑等古土壤特征，系古土壤。软锰矿的分布指示地下水位在地面上下３ｍ左右，这由于冰期低海面本区相对海拔较大所致。     

江西玉山县王家坝晚奥陶世三衢山组点礁发育特征及其群落研究

本文研究了玉山王家坝晚奥陶世三衢山组的点礁,描记了三个生物群落:Sibiriolites jiangxiensis群落,Fletcheriella grandis-Pachystylostroma群落和Trocholites-Encrinuroides群落.依据造礁功能的不同,作者还简述了组成点礁的各种生物群团.     

"诗史"精神重放光辉--论宋末诗人对杜诗的接受

南宋末年,在文天祥以身殉国、忠义存诗存史的影响下,一大批南宋遗民、诗人奋起直笔,模仿杜诗,以诗存史,而且往往在诗前另以序言辅以记史.