On Generalization of a Question of Entrance Test for MA Candidates

2004年漳州师范学院硕士研究生入学考试中有一道高等代数试题,是关于实对称阵的所有正特征根之和与其迹所确定的不等式。证明了这个不等式可推广到实矩阵上去,即实矩阵的所有实部为正的特征根之和与其迹也有类似不等式,同时给出了其等号成立的充要条件。In Entrance Test of Higher Algebra of Zhangzhou Terachers Colleage for MA/MS Candidates in 2004,there is a question on inequality,which is determined by the summation of all positive eigenvalues of real symmetric matrix and its trace.This paper proves that this inequality can be generalized in real matrix,i.e.,there is a similar inequality for the summation of all positive real part of eigenvalues of real matrix and its trace,and we also give the necessary and sufficient conditions for the equality.福建省自然科学基金项目(Z0511051);; 福建省2006年本科精品课程——高等代数;; 莆田学院数学研究项目(JG200521

论司马迁经济思想的现代契合与观照

司马迁的经济思想主要体现在《史记》一书中。《史记》成书距今已有2000多年时间,但其中所蕴含的经济思想与现代经济思想比较,却有许多异曲同工之处。基于此,本文以现代经济学的视角对司马迁的经济思想进行探析

双翼振动的预处理数值方法和性能研究(二)

本文利用非定常双时间NS方程的预处理方法对摆翼地效推进器进行了推力和推进性能的分析,结果显示沉浮振动的推力和效率与速度的变化关系表现出一致性;固定频率,改变速度,发现推力和效率存在极大值点;随着频率增大,极大值点右移。最大推力和效率的动力攻角为6°～9°,利用速度矢量图和压力云图显示了分离涡的输运和扩散,再一次展示了地效的存在

Preliminary studies on the scale insect pest of Pseudaulacaspis cockerelli in mangrove

首次发现陆生考氏白盾蚧严重为害潮间带红树植物秋茄。通过野外定位调查和室内饲养观察,研究其危害特征、种群分布、生殖力和自然死亡率。结果表明,考氏白盾蚧主要分布在秋茄叶片主脉两侧,叶背虫口数显著多于叶面(P<0.01),单叶虫口数多为1-50头,平均25.65头,最高418头;秋茄植株不同垂直空间层次的虫口密度无显著差异,但聚集度随垂直空间下降而增大;种群平均产卵量每雌52.22粒,自然死亡率69.35%,寄生蜂寄生是最主要的死亡因子,寄生率达34.23%;与几种陆生寄主植物相比,红树林考氏白盾蚧的种群密度、生殖力、叶最高虫口数均较高,该虫对潮间带生境及寄主秋茄具有适应性。The scale insect,Pseudaulacaspis cockerelli is an important pest for many kinds of plants for a long time in the land.In 2006,it was found firstly attacking the mangrove plant of Kandelia obovata in the tideland in Xiamen City,and had led to badly damages.Based on the field surveys and lab feeding,this paper dealed with its damage characteristic,population distribution,fecundity and natural mortality etc.The results showed that the scale insect mainly distributed on both sides of the midvien of K.obovata leaves,but the individual on the abaxial surface was significantly more than those on the adaxial surface(P<0.01).The individual number of one leaf mostly fluctuated from 1 to 50,and the average and tiptop numbers were 25.65 and 418,respectively.The pest population density had no remarkable discrepancies among different vertical spatial layer of K.obovata,however,its aggregating degree increased with falling of the layer.The population had an avarage fecundity of 52.22 each female and a high natural mortality of 69.53%.The main natural death factor were two species of parasites(Hymenoptera: Chalcididae),and their total parasitical ratio reached 34.23%.In the mass,the pest population density,fecundity and tiptop individual number of a leaf in the mongrove were all more than those in serval other host plants on land,which implied that this scale insect had a high adaptability to the habitat of tideland and the plant of K.obovata

Numerical investigation of flow structures resulting from the interaction between an oblique detonation wave and an upper expansion corner

Wedge-induced oblique detonation waves (ODWs) have been studied widely, but their interactions with complicated geometries have not been fully addressed. In this study, we investigate ODW interaction with a deflected upper corner due to confinement change upstream of the ODW. Numerical simulations are conducted using the reactive Euler equations with a two-step induction-reaction kinetic model. Two ODWs without the upper wall deflection are first simulated to resolve the basic structures with inflow Mach numbers M-0 = 6 and 7. Thereafter, we introduce a deflected upper confinement, resulting in a new wave configuration. This wave is characterized by a post-turning, triangular recirculation zone coupled with a gaseous wedge connecting the deflection point and ODW surface. A parametric study is performed to analyse the effects of the deflection location, deflection angle and activation energy of the heat release reaction. The results reveal that the wave configuration is due to the evolution of ODW decoupling in an expanded supersonic flow. We further study the surface stability and structural unsteadiness arising for M-0 = 6. Upstream-travelling transverse waves are observed for the first time, and effects of different parameters on the surface instability are analysed via fast Fourier transforms. Two destabilizing mechanisms of ODW structures are proposed, one from the post-surface thermal choking and the other from the enhanced surface instability

Numerical study of oblique detonation initiations with chain-branching kinetics

Oblique detonations induced by semi-infinite wedge are simulated by solving Euler equations with chain branching kinetics. Numerical results show the initiation can be triggered by either the abrupt transition or smooth transition, dependent on incident Ma Minand wedge angle 胃, and then their effects on the oblique detonation angle 尾 and initiation length Liniare analyzed. When 胃 increases, Linidecreases monotonically but 尾 has a minimum value, corresponding to 胃 = 29掳 in this study. When Min decreases, both Liniand 尾 increases monotonically until Mindecreases below certain critical value, Min= 9.2 in this study. Then low inflow Ma effects generate the maximum Lini, with the complex of ODW (oblique detonation wave), SODW (secondary oblique detonation wave) and SIDW (self-ignition deflagration wave). The transient process is observed, demonstrating the structure can self-adjust to find a proper position. The wave structure suggests two wave/heat release process determining the detonation initiation. In the cases with high Minfeatured by SIDW, the oblique-shock induced self-ignition dominates, and Liniincreases when Mindecreases. In the cases with low Minfeatured by SODW, the interaction of ODW and SODW dominates, and Linidecreases when Min decreases. 漏 2017 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.</p

补阳还五汤冲洗联合负压封闭引流技术治疗四肢软组织缺损创面的临床研究

目的:探讨补阳还五汤冲洗联合负压封闭引流技术(VSD)治疗四肢软组织缺损创面的临床疗效。方法:将57例慢性四肢软组织缺损创面患者行VSD治疗后随机分为补阳还五汤冲洗组(A组,n=29)和生理盐水冲洗组(B组,n=28),术后观察并比较两组患者的炎症指标变化、细菌培养结果、1周后肉芽组织覆盖率和首次植皮成活率情况。结果:两组患者术后及术后3 d的CRP比较,差异无统计学意义(P>0.05),而术后7 d及14 d,A组患者CRP低于B组(P0.05);A组患者术后14 d的ESR及白细胞计数明显低于B组(P<0.05)。术后1周A、B组平均肉芽组织覆盖率分别为(81.86±5.74)%和(73.11±4.19)%,两组差异有统计学意义(P<0.05)。拆除VSD后细菌培养结果显示:A组阴性为20例(70.0%),明显高于B组的11例(39.3%),差异有统计学意义(P<0.05)。A组有24例(82.8%)首次植皮或皮瓣转移成功闭合创面,B组有16例(57.1%)首次植皮成活,两组首次植皮成活率比较,差异有统计学意义(P<0.05)。结论:补阳还五汤冲洗联合VSD治疗四肢软组织缺损创面能降低炎症反应、促进肉芽组织生长、缩短植皮时间,提高植皮成活率。福建中医药大学校管课题(XB2017079

Comparative Study on Characteristics of Urban Rainfall Runoff from Two Urban Lawn Catchments in Macau and Xiamen

在澳门与厦门分别选一分流制管道类型的绿地小流域开展降雨径流监测,以研究城市绿地降雨径流污染特征.结果表明,两城市绿地小流域降雨径流的主要污染物为COd、TP、nO3--n,其EMC平均值分别为165.77--60.48 Mg/l、0.96--0.44 Mg/l和7.16--1.18 Mg/l;两城市绿地的COd、TP、nO3--n污染负荷平均值分别为6.53--0.63 kg/HM2、0.037 5--0.004 7 kg/HM2和0.012 2--0.012 8 kg/HM2;绿地降雨径流污染物浓度峰值出现时间早于径流量峰值;城市绿地降雨径流初始冲刷效应不明显,厦门绿地小流域降雨径流COd、TSS、TP及nO3--n的ff30分别为36.26%、26.13%、28.13%和39.03%.基于多元回归分析结果表明,总降雨量和总径流量是影响绿地降雨径流污染初始冲刷效应的主要因素.A comparative study on characteristics of stormwater runoff from two urban lawn catchments in Macau(ELH) and Xiamen(PGH) with separated sewer system were conducted.The result obtained shows that COD,TP and(NO---_3-N) are the major pollutants with mean EMC of 165.77-60.48(mg/L),0.96-0.44(mg/L) and 7.16-1.18(mg/L),respectively,and the mean values of pollutants loads of COD,TP and(NO---_3-N) from study lawn catchments are 6.53-0.63(kg/hm--2),(0.037?5)-(0.004?7)(kg/hm--2) and(0.012?2)-(0.012?8)(kg/hm--2),respectively.Peak values of major pollutant concentrations usually precede the flow peak.First flush effect of rainfall runoff from two study catchments is no obvious,which can be reflected by the low mean value of FF_(30) of TSS,COD,TP and(NO---_3-N),with 36.26%,26.13%,28.13% and 39.03%,respectively.Based on multivariate statistical analysis,first flush effect from urban lawn rainfall runoff is greatly influenced by total rainfall amount(T_r) and total runoff volume(V).国家自然科学基金项目(50778098);福建省青年人才项目(2007F3093

社会系统工程与国家治理体系现代化

2014年3月30日,中国人民大学国家发展与战略研究院社会系统工程研究中心成立暨“社会系统工程与国家治理体系现代化“学术研讨会在中国人民大学逸夫会堂第一会议室举行,来自十余所高校和学术团体的专家、学者和一些媒体的代表参加了会议。现把会议主要发言内容选载如下

1978～2008年中国湿地类型变化

分别基于美国陆地卫星(Landsat MSS/TM/ETM+)和中巴资源卫星(CBERS-02B)影像数据,以人工目视解译为主,完成了中国1978～2008年4期(基准年分别为1978,1990,2000和2008年)湿地遥感制图,并进行了大量的室内外验证.在此基础上,对我国湿地现状及近30年来湿地变化进行了初步分析,得到以下主要结论:(ⅰ)截止2008年,中国湿地面积约为324097km2,其中以内陆沼泽(35%)和湖泊湿地(26%)为主.(ⅱ)1978～2008年,中国湿地面积减少了约33%,而人工湿地增加了约122%.过去30年里湿地减少的速度大幅降低,由最初5523km2/a(1978～1990年)降为831km2/a(2000～2008年).(ⅲ)减少的自然湿地(包括滨海湿地和内陆湿地),其类型变化由湿地向非湿地转化的比例逐渐降低.初期(1978～1990年)几乎全部(98%)转换为非湿地;在1990～2000年间减少的自然湿地约有86%转化为非湿地,而在2000～2008年,这一比例下降为77%.(ⅳ)气候变化和农业活动是中国湿地变化的主要驱动因素,湿地变化在中国分为三大不同特征区域,即西部三省/自治区(西藏、新疆和青海)、北部两省/自治区(黑龙江和内蒙古)和其他省市区.其中西部区域尤其是青藏高原,湿地变化的驱动因子以气候增温为主;新疆湿地由于气候增温和农业活动共同作用造成变化不大.北部省/自治区的湿地变化则主要由农业活动引起;而其他省市区的湿地变化几乎完全受控于人类的农业经济活动