期刊文献+
共找到69,458篇文章
< 1 2 250 >
每页显示 20 50 100
Greatly enhanced corrosion/wear resistances of epoxy coating for Mg alloy through a synergistic effect between functionalized graphene and insulated blocking layer 被引量:1
1
作者 Z.Y.Xue X.J.Li +3 位作者 J.H.Chu M.M.Li D.N.Zou L.B.Tong 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2024年第1期332-344,共13页
The poor corrosion and wear resistances of Mg alloys seriously limit their potential applications in various industries.The conventional epoxy coating easily forms many intrinsic defects during the solidification proc... The poor corrosion and wear resistances of Mg alloys seriously limit their potential applications in various industries.The conventional epoxy coating easily forms many intrinsic defects during the solidification process,which cannot provide sufficient protection.In the current study,we design a double-layer epoxy composite coating on Mg alloy with enhanced anti-corrosion/wear properties,via the spin-assisted assembly technique.The outer layer is functionalized graphene(FG)in waterborne epoxy resin(WEP)and the inner layer is Ce-based conversion(Ce)film.The FG sheets can be homogeneously dispersed within the epoxy matrix to fill the intrinsic defects and improve the barrier capability.The Ce film connects the outer layer with the substrate,showing the transition effect.The corrosion rate of Ce/WEP/FG composite coating is 2131 times lower than that of bare Mg alloy,and the wear rate is decreased by~90%.The improved corrosion resistance is attributed to the labyrinth effect(hindering the penetration of corrosive medium)and the obstruction of galvanic coupling behavior.The synergistic effect derived from the FG sheet and blocking layer exhibits great potential in realizing the improvement of multi-functional integration,which will open up a new avenue for the development of novel composite protection coatings of Mg alloys. 展开更多
关键词 Mg alloy Functionalized graphene Epoxy coating Corrosion/wear resistance blocking layer
下载PDF
A nanobody-based blocking enzyme-linked immunosorbent assay for detecting antibodies against pseudorabies virus glycoprotein E
2
作者 Huanhuan Lü Pinpin Ji +6 位作者 Siyu Liu Ziwei Zhang Lei Wang Yani Sun Baoyuan Liu Lizhen Wang Qin Zhao 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2024年第4期1354-1368,共15页
Pseudorabies(PR)is an acute infectious disease of pigs caused by the PR virus(PRV)and results in great economic losses to the pig industry worldwide.PRV glycoprotein E(gE)-based enzyme-linked immunosorbent assay(ELISA... Pseudorabies(PR)is an acute infectious disease of pigs caused by the PR virus(PRV)and results in great economic losses to the pig industry worldwide.PRV glycoprotein E(gE)-based enzyme-linked immunosorbent assay(ELISA)has been used to distinguish gE-deleted vaccine-immunized pigs from wild-type virus-infected pigs to eradicate PR in some countries.Nanobody has the advantages of small size and easy genetic engineering and has been a promising diagnostic reagent.However,there were few reports about developing nanobody-based ELISA for detecting anti-PRV-gE antibodies.In the present study,the recombinant PRV-gE was expressed with a bacterial system and used to immunize the Bactrian camel.Then,two nanobodies against PRV-gE were screened from the immunized camel by phage display technique.Subsequently,two nanobody-HRP fusion proteins were expressed with HEK293T cells.The PRV-gE-Nb36-HRP fusion protein was selected as the probe for developing the blocking ELISA(bELISA)to detect anti-PRV-gE antibodies.Through optimizing the conditions of bELISA,the amount of coated antigen was 200 ng per well,and dilutions of the fusion protein and tested pig sera were separately 1:320 and 1:5.The cut-off value of bELISA was 24.20%,and the sensitivity and specificity were 96.43 and 92.63%,respectively.By detecting 233 clinical pig sera with the developed bELISA and a commercial kit,the results showed that the coincidence rate of two assays was 93.99%.Additionallly,epitope mapping showed that PRV-gE-Nb36 recognized a conserved conformational epitope in different reference PRV strains.Simple,great stability and low-cost nanobody-based bELISA for detecting anti-PRV-gE antibodies were developed.The bELISA could be used for monitoring and eradicating PR. 展开更多
关键词 NANOBODY nanobody-HRP blocking ELISA PRV-gE ANTIBODY
下载PDF
Development and performance evaluation of high temperature resistant strong adsorption rigid blocking agent
3
作者 Zhe Xu Jin-Sheng Sun +6 位作者 Jing-Ping Liu Kai-He Lv Xiao-Dong Dong Zong-Lun Wang Tai-Feng Zhang Yuan-Wei Sun Zhi-Wen Dai 《Petroleum Science》 SCIE EI CAS CSCD 2024年第4期2650-2662,共13页
As drilling wells continue to move into deep ultra-deep layers,the requirements for temperature resistance of drilling fluid treatments are getting higher and higher.Among them,blocking agent,as one of the key treatme... As drilling wells continue to move into deep ultra-deep layers,the requirements for temperature resistance of drilling fluid treatments are getting higher and higher.Among them,blocking agent,as one of the key treatment agents,has also become a hot spot of research.In this study,a high temperature resistant strong adsorption rigid blocking agent(QW-1)was prepared using KH570 modified silica,acrylamide(AM)and allyltrimethylammonium chloride(TMAAC).QW-1 has good thermal stability,average particle size of 1.46μm,water contact angle of 10.5.,has a strong hydrophilicity,can be well dispersed in water.The experimental results showed that when 2 wt%QW-1 was added to recipe A(4 wt%bentonite slurry+0.5 wt%DSP-1(filtration loss depressant)),the API filtration loss decreased from 7.8to 6.4 m L.After aging at 240.C,the API loss of filtration was reduced from 21 to 14 m L,which has certain performance of high temperature loss of filtration.At the same time,it is effective in sealing 80-100mesh and 100-120 mesh sand beds as well as 3 and 5μm ceramic sand discs.Under the same conditions,the blocking performance was superior to silica(5μm)and calcium carbonate(2.6μm).In addition,the mechanism of action of QW-1 was further investigated.The results show that QW-1 with amide and quaternary ammonium groups on the molecular chain can be adsorbed onto the surface of clay particles through hydrogen bonding and electrostatic interaction to form a dense blocking layer,thus preventing further intrusion of drilling fluid into the formation. 展开更多
关键词 High adsorption Rigid microsphere High temperature resistance blocking performance
下载PDF
CRB:A new rumor blocking algorithm in online social networks based on competitive spreading model and influence maximization
4
作者 董晨 徐桂琼 孟蕾 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第8期588-604,共17页
The virtuality and openness of online social platforms make networks a hotbed for the rapid propagation of various rumors.In order to block the outbreak of rumor,one of the most effective containment measures is sprea... The virtuality and openness of online social platforms make networks a hotbed for the rapid propagation of various rumors.In order to block the outbreak of rumor,one of the most effective containment measures is spreading positive information to counterbalance the diffusion of rumor.The spreading mechanism of rumors and effective suppression strategies are significant and challenging research issues.Firstly,in order to simulate the dissemination of multiple types of information,we propose a competitive linear threshold model with state transition(CLTST)to describe the spreading process of rumor and anti-rumor in the same network.Subsequently,we put forward a community-based rumor blocking(CRB)algorithm based on influence maximization theory in social networks.Its crucial step is to identify a set of influential seeds that propagate anti-rumor information to other nodes,which includes community detection,selection of candidate anti-rumor seeds and generation of anti-rumor seed set.Under the CLTST model,the CRB algorithm has been compared with six state-of-the-art algorithms on nine online social networks to verify the performance.Experimental results show that the proposed model can better reflect the process of rumor propagation,and review the propagation mechanism of rumor and anti-rumor in online social networks.Moreover,the proposed CRB algorithm has better performance in weakening the rumor dissemination ability,which can select anti-rumor seeds in networks more accurately and achieve better performance in influence spread,sensitivity analysis,seeds distribution and running time. 展开更多
关键词 online social networks rumor blocking competitive linear threshold model influence maximization
下载PDF
Clinical Nursing Intervention of Moxibustion on Abdominal Distension Symptoms in Heart Failure (Heart and Kidney Yang Deficiency and Blood Stasis Blocking Collaterals Syndrome)
5
作者 Tingcui Yan 《Journal of Clinical and Nursing Research》 2024年第6期142-147,共6页
Objective:To investigate the clinical nursing intervention effect of moxibustion on abdominal distension symptoms in heart failure(heart and kidney yang deficiency and blood stasis blocking collaterals syndrome).Metho... Objective:To investigate the clinical nursing intervention effect of moxibustion on abdominal distension symptoms in heart failure(heart and kidney yang deficiency and blood stasis blocking collaterals syndrome).Methods:62 patients with heart failure(heart and kidney yang deficiency and blood stasis blocking collaterals syndrome)admitted to our hospital from February 2023 to February 2024 were selected and divided into the observation group(n=31)and the control group(n=31)by using the random numerical table method.The control group adopted conventional nursing interventions,and the observation group received the nursing program of the control group with the addition of moxibustion nursing interventions.The nursing effectiveness,quality of life scores,and nursing satisfaction were compared between the two groups.Results:The nursing effectiveness of the observation group was significantly higher than the control group(P<0.05);the quality of life score of the observation group was significantly higher than the control group(P<0.05);the nursing satisfaction of the observation group was significantly higher than that of the control group(P<0.05).Conclusion:The use of moxibustion nursing intervention in patients with heart failure(heart and kidney yang deficiency and blood stasis blocking collaterals syndrome)can effectively relieve the symptoms of abdominal distension,improve patients'quality of life,and increase nursing satisfaction,which has promotion and application values. 展开更多
关键词 MOXIBUSTION Heart failure Heart and kidney yang deficiency and blood stasis blocking collaterals syndrome Abdominal distension Nursing intervention
下载PDF
安氏Ⅱ类错[牙合]畸形佩戴Twin-block矫治器时上颌骨的应力分布
6
作者 李帅 刘桦 +3 位作者 商永慧 刘义琮 赵启航 刘文 《中国组织工程研究》 CAS 北大核心 2025年第5期881-887,共7页
背景:Twin-block矫治器常用于安氏Ⅱ类错[牙合]畸形的矫治,其刺激下颌骨生长的作用机制已得到许多研究证实,但对上颌骨生长的影响尚不清楚。目的:通过有限元法分析安氏Ⅱ类错[牙合]畸形患者佩戴Twin-block矫治器时上颌骨复合体、周围骨... 背景:Twin-block矫治器常用于安氏Ⅱ类错[牙合]畸形的矫治,其刺激下颌骨生长的作用机制已得到许多研究证实,但对上颌骨生长的影响尚不清楚。目的:通过有限元法分析安氏Ⅱ类错[牙合]畸形患者佩戴Twin-block矫治器时上颌骨复合体、周围骨缝及上颌牙列的应力分布。方法:选择在山东省康复大学青岛医院/青岛市市立医院口腔正畸科进行正畸治疗的安氏Ⅱ类错[牙合]畸形患者1例,测量患者佩戴Twin-block矫治器时的咬合力数据,采集其锥形束CT数据,建立包含上颌骨复合体、周边各骨缝、Twin-block矫治器及上颌牙列在内的有限元模型,通过ABAQUS软件模拟患者戴入Twin-block时上颌骨、骨缝及上颌牙列的应力分布与位移。结果与结论:①上颌前牙受到的等效应力明显小于后牙,两侧牙齿的最大等效应力分别为4.7975 MPa和8.7161 MPa,均位于第一前磨牙处;最大位移呈现在两侧上颌切牙处,分别为0.0805 mm和0.0810 mm;②骨缝的最大等效应力为1.284 MPa,主要集中在两侧翼腭缝及额颌缝,其余骨缝受力情况几乎无差异;骨缝的最大位移为0.07 mm,其中翼腭缝的位移量最大,其次是额颌缝;③上颌骨复合体受到的最大等效应力为27.18 MPa,主要集中在上颌骨前面梨状孔两侧、鼻额缝周边及颚骨后部翼腭缝附近;上颌骨的最大位移值为0.07 mm,主要集中于上颌牙槽骨;④结果显示,咬合力通过Twin-block矫治器作用于上颌骨复合体,导致上颌骨顺时针旋转、牙合平面变陡,应采取相应措施补偿这种趋势,例如建牙合过程中考虑上颌磨牙伸长、下颌磨牙压低,不仅能够将牙合平面整平,同时有利于下颌前伸,这将进一步提高Ⅱ类错[牙合]正畸治疗效果。 展开更多
关键词 错牙合畸形 组织构建 骨组织工程 TWIN-block矫治器 功能矫治 有限元分析
下载PDF
P-block基金属原子在TiO_(2)(110)表面的吸附及扩散性质研究
7
作者 丁雅妮 郭梦雨 +3 位作者 王博涵 贾晨怡 王美娟 史金磊 《原子与分子物理学报》 CAS 北大核心 2025年第6期17-21,共5页
基于密度泛函理论的第一性原理计算方法,我们系统研究了p-block金属原子(Sn,Sb,Bi和Te)在TiO_(2)(110)表面上的吸附及扩散行为.计算结果表明Sn,Sb及Bi金属原子在TiO_(2)(110)表面上具有较大的吸附能和较高的扩散势垒,倾向于形成分散的p-... 基于密度泛函理论的第一性原理计算方法,我们系统研究了p-block金属原子(Sn,Sb,Bi和Te)在TiO_(2)(110)表面上的吸附及扩散行为.计算结果表明Sn,Sb及Bi金属原子在TiO_(2)(110)表面上具有较大的吸附能和较高的扩散势垒,倾向于形成分散的p-block单原子,然而对于Te金属原子,由于其与衬底结合能相对较弱且扩散势垒较低而更倾向于形成团簇,该研究结果有助于为实验上构建基于p-block的金属单原子催化剂提供理论依据. 展开更多
关键词 p-block单原子催化剂 吸附及扩散势垒 第一性原理计算
下载PDF
Blocking流水车间调度问题的MBT算法研究 被引量:2
8
作者 洪宗友 闫萍 庞哈利 《辽宁师范大学学报(自然科学版)》 CAS 北大核心 2007年第2期148-151,共4页
针对目标函数为Makespan的Blocking流水车间调度问题,设计了一种构造启发式算法.初始排序的产生从减少下游工件的滞留时间入手,结合有向图中对关键路径的分析,采用插入规则进行搜索的方法得到工件序列的近优排序.通过大量典型算例的计算... 针对目标函数为Makespan的Blocking流水车间调度问题,设计了一种构造启发式算法.初始排序的产生从减少下游工件的滞留时间入手,结合有向图中对关键路径的分析,采用插入规则进行搜索的方法得到工件序列的近优排序.通过大量典型算例的计算,实验结果证明了设计的算法具有优越的性能. 展开更多
关键词 流水车间调度 启发式算法 blocking流水车间
下载PDF
Study on Screening of Optimal Blocking Buffer and Sample Diluent for ELISA 被引量:2
9
作者 杜改梅 刘茂军 +3 位作者 甘源 韦艳娜 武昱孜 邵国青 《Agricultural Science & Technology》 CAS 2013年第6期816-819,837,共5页
[Objective] This study aimed to increase the sensitivity and specificity of enzyme-linked immunosorbent assay (ELISA) through analyzing the effects of different blocking buffers and sample diluents and their differe... [Objective] This study aimed to increase the sensitivity and specificity of enzyme-linked immunosorbent assay (ELISA) through analyzing the effects of different blocking buffers and sample diluents and their different concentrations on the result of ELISA. [Method] Different types of blocking buffer [casein, gelatin, BSA, goat serum (GS), horse serum (HS) and rabbit serum (RS)]and sample diluent (PBST, casein, gelatin, BSA, GS, HS and RS) as well as their different concentrations were tested in ELISA to screen the optimal combination of blocking buffer and sample diluent. [Result] The results showed that 2% BSA had better effect on blocking than 1% and 3% BSA, and both 2% and 1% casein had better blocking effect than 3% casein; 8% and 10% RS showed better blocking effects than 6%RS and 7%RS; compared to BSA and casein, RS had the best effect on blocking, and 8% RS performed best as the blocking buffer and sample diluent. [Conclusion] A good combination of blocking buffer and diluent can effectively reduce the non-specific reaction and improve the sensitivity and specificity of ELISA. This study provides an important reference for the development of a perfect ELISA method. 展开更多
关键词 blocking buffer Sample diluent ELISA
下载PDF
NUMERICAL ANALYSIS OF FLOW CHARACTERISTICS IN BLOCKING OF THE YANGTZ RIVER OF THE TGP 被引量:2
10
作者 魏文礼 刘玉玲 金忠青 《Transactions of Tianjin University》 EI CAS 2001年第2期113-117,共5页
Some novel techniques of computational fluid dynamics are used to establish a mathematical model for the open diversion channel with two embankments in river blocking.The technique of boundary fitted coordinate syste... Some novel techniques of computational fluid dynamics are used to establish a mathematical model for the open diversion channel with two embankments in river blocking.The technique of boundary fitted coordinate system is used to overcome the difficulties resulting from the complicated shapes of natural river boundaries;the method of alternating direction implicit finite difference scheme is used to solve the partial differential equations in the transformed plane;and the technique of moving boundary is used to deal with the river bed exposed to water surface.This model has been used to predict the flow characteristics in the blocking of the Yangtz river in the Three Gorge Project (TGP).Comparison between the computed and experimental data shows a satisfactory agreement. 展开更多
关键词 river blocking flow characteristics mathematical model
下载PDF
关于一维排它过程平稳blocking测度的存在性
11
作者 黄旭东 汪世界 《应用数学》 CSCD 北大核心 2004年第3期417-423,共7页
本文证明了具有非平移不变转移速率p(x ,y)的一维排它过程平稳blocking测度的存在性 ,推广了文献 [5]中的有关结果 .
关键词 排它过程 耦合 平稳测度 blocking测度 转移速率 连续时间马尔科夫过程
下载PDF
改进的路由协议BLOCKING-COMPOW 被引量:3
12
作者 张文彬 杨孝宗 《计算机工程与应用》 CSCD 北大核心 2011年第16期89-92,共4页
COMPOW功率控制协议通过控制所有的节点采用相同的发射功率来保证网络消耗功率最小化,但该协议不适用于节点分布不均匀的网络。此协议的改进版本CLUSTERPOW可以降低不均匀网络中的能耗,但此协议在节点分布均匀网络中的性能较差。针对两... COMPOW功率控制协议通过控制所有的节点采用相同的发射功率来保证网络消耗功率最小化,但该协议不适用于节点分布不均匀的网络。此协议的改进版本CLUSTERPOW可以降低不均匀网络中的能耗,但此协议在节点分布均匀网络中的性能较差。针对两种协议的不足之处,提出了一种新路由协议BLOCKING-COMPOW,仿真结果表明这种新协议在各种节点分布下都具有较好的性能。 展开更多
关键词 COMPOW协议 CLUSTERPOW协议 blocking-COMPOW协议
下载PDF
基于工件间隙的Blocking流程车间调度启发式算法
13
作者 洪宗友 庞哈利 《计算机应用》 CSCD 北大核心 2007年第B12期159-161,共3页
考虑Blocking流程车间调度的特殊性质,提出一种基于工件间隙以达到减少机器闲置和工件滞留时间的初始排序规则,结合插入搜索机制,构造解决Blockjng流程车间的调度问题的启发式算法。通过大量的计算实验并与有效地解决该调度问题的NEH算... 考虑Blocking流程车间调度的特殊性质,提出一种基于工件间隙以达到减少机器闲置和工件滞留时间的初始排序规则,结合插入搜索机制,构造解决Blockjng流程车间的调度问题的启发式算法。通过大量的计算实验并与有效地解决该调度问题的NEH算法进行比较,结果表明本算法在解的质量上有改进。 展开更多
关键词 blocking 流程车间 调度 启发式算法
下载PDF
基于改进Blocking策略的模型预测控制技术 被引量:1
14
作者 潘健 刘昌龙 《湖北工业大学学报》 2017年第1期51-55,共5页
针对模型预测控制(MPC)在线优化计算复杂的缺陷,在采用输入分块(Input blocking)策略对输入序列进行固定分块的基础上,,提出了一种移动分块(Move blocking)策略,通过变化的blocking矩阵降低控制量的自由度,从而有效降低模型预测控制在... 针对模型预测控制(MPC)在线优化计算复杂的缺陷,在采用输入分块(Input blocking)策略对输入序列进行固定分块的基础上,,提出了一种移动分块(Move blocking)策略,通过变化的blocking矩阵降低控制量的自由度,从而有效降低模型预测控制在线优化过程中的计算复杂度。同时能够在满足约束条件下保证系统输出紧密跟踪期望值。以四旋翼无人机系统为控制对象,在构建模型基础上,仿真验证了该算法的有效性。 展开更多
关键词 MPC 移动分块 计算复杂度
下载PDF
Perirenal space blocking restores gastrointestinal function in patients with severe acute pancreatitis 被引量:8
15
作者 Jun-Jun Sun Zhi-Jie Chu +7 位作者 Wei-Feng Liu Shi-Fang Qi Yan-Hui Yang Peng-Lei Ge Xiao-Hui Zhang Wen-Sheng Li Cheng Yang Yu-Ming Zhang 《World Journal of Gastroenterology》 SCIE CAS 2013年第46期8752-8757,共6页
AIM:To investigate effects of perirenal space blocking(PSB)on gastrointestinal function in patients with severe acute pancreatitis(SAP).METHODS:Forty patients with SAP were randomly allocated to receive PSB or no PSB(... AIM:To investigate effects of perirenal space blocking(PSB)on gastrointestinal function in patients with severe acute pancreatitis(SAP).METHODS:Forty patients with SAP were randomly allocated to receive PSB or no PSB(NPSB).All the SAP patients received specialized medical therapy(SMT).Patients in the PSB group received PSB+SMT when hospitalized and after diagnosis,whereas patients in the NPSB group only received SMT.A modifed gastrointestinal failure(GIF)scoring system was used to assess the gastrointestinal function in SAP patients after admission.Pain severity(visual analog scale,0 to100)was monitored every 24 h for 72 h.RESULTS:Modified GIF score decreased in both groups during the 10-d study period.The median score decrease was initially significantly greater in the PSB group than in the NPSB group after PSB was per-formed.During the 72-h study period,pain intensity decreased in both groups.The median pain decrease was significantly greater in the PSB group than in the NPSB group at single time points.Patients in the PSB group had significantly lower incidences of hospital mortality,multiple organ dysfunction syndrome,systemic inflammatory response syndrome,and pancreatic infection,and stayed in the intensive care unit for a shorter duration.However,no difference in terms of operation incidence was found between the two groups.CONCLUSION:PSB could ameliorate gastrointestinal dysfunction or failure during the early stage of SAP.Moreover,PSB administration could improve prognosis and decrease the mortality of SAP patients. 展开更多
关键词 Perirenal space blocking THERAPEUTICS SEVERE acute PANCREATITIS GASTROINTESTINAL function PROGNOSIS
下载PDF
Review of Infrared signature suppression systems using optical blocking method 被引量:12
16
作者 Nidhi Baranwal Shripad P. Mahulikar 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2019年第3期432-439,共8页
With rapid advancements in Infra-Red (IR) detection techniques, the range from where the IR-guided missiles are able to lock the target aircraft has increased. To avoid the detection and tracking by modern IR-guided m... With rapid advancements in Infra-Red (IR) detection techniques, the range from where the IR-guided missiles are able to lock the target aircraft has increased. To avoid the detection and tracking by modern IR-guided missiles, the aircraft and helicopters also demand progress in its stealth techniques. Hence, study of Infra-Red Signature Suppression (IRSS) systems in aircraft and helicopters has become vital even in design stage. Optical blocking (masking) is one of the effective IRSS techniques used to block the Line- Of-Sight (LOS) of the hot engine parts of the exhaust geometry. This paper reviews the various patents on IR signature suppression systems based on the optical blocking method or a combination of IRSS techniques. The performance penalties generated due to installation of various IRSS methods in aircraft and helicopters are also discussed. 展开更多
关键词 IR SIGNATURE SUPPRESSION OPTICAL blocking Performance PENALTY IR SIGNATURE level Engine back-pressure
下载PDF
Interaction between Planetary-Scale Diffluent Flow and Synoptic-Scale Waves During the Life Cycle of Blocking 被引量:4
17
作者 罗德海 刘金婷 李建平 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2010年第4期807-831,共25页
In this paper, a new transient forced quasi-resonant triad interaction theory in a beta channel is proposed to investigate the interaction between planetary-scale diffluent flow composed of zonal wavenumbers 1-3 and s... In this paper, a new transient forced quasi-resonant triad interaction theory in a beta channel is proposed to investigate the interaction between planetary-scale diffluent flow composed of zonal wavenumbers 1-3 and synoptic-scale waves produced continuously by a synoptic-scale vorticity source fixed upstream of an incipient blocking region during the life cycle of blocking. It is shown that the superposition of initial three Rossby waves for zonal wavenumbers 1 (monopole), 2 (dipole), and 3 (monopole), which permit triad quasi-resonance, can represent an incipient blocking event. The synoptic-scale eddies may act to amplify the incipient blocking and to excite a blocking circulation with a strong meander, whose flow pattern depends on the initial amplitudes of the planetary waves and both the intensity and location of preexisting synoptic-scale waves. The onset (decay) of the planetary-scale split-flow blocking is mainly represented by a strong increase (decrease) in the amplitude of the zonal wavenumber 2 component, having a dipole meridional structure related to the preexisting synoptic-scale eddies. The typical persistence time of the model blocking was of about 20 days, consistent with observations of blocking patterns. In our model, isolated asymmetric dipole blocking is formed by synoptic-scale waves. The instantaneous fields of total streamfunctions exhibit a remarkable resemblance to the synoptic maps observed during the life cycle of blocking. During the onset stage, the synoptic-scale waves are enhanced and split into two branches around the blocking region due to the feedback of the amplified blocking, in agreement with the observed changes of synoptic-scale waves in real blocking events. In addition, a diagnostic case study of blocking is presented to confirm the forced quasi-resonant triad interaction theory proposed here. 展开更多
关键词 quasi-resonant triad interaction blocking waves synoptic-scale waves blocking case
下载PDF
Barotropic Interaction between Planetary-and Synoptic-Scale Waves during the Life Cycles of Blockings 被引量:9
18
作者 罗德海 李建平 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2000年第4期649-670,共22页
In this paper, in an equivalent barotropic framework a new forced nonlinear Schroedinger equation is proposed to examine the interaction between the planetary-scale waves and the localized synoptic-scale eddies upstre... In this paper, in an equivalent barotropic framework a new forced nonlinear Schroedinger equation is proposed to examine the interaction between the planetary-scale waves and the localized synoptic-scale eddies upstream. With the help of the perturbed inverse scattering transform method, nonlinear parameter equations can be derived to describe the evolution of the dipole soliton amplitude, frequency, group velocity and phase under the forcing of localized synoptic-scale eddies. The numerical solutions of these equations predict that in the interaction between the weak dipole soliton (weak incipient dipole anomaly) and the synoptic-scale eddies, only when the high-frequency eddies themselves have a moderate parameter match they can near resonantly enhance a quasi-stationary large-amplitude split flow. The instantaneous total streamfunction field (the sum of background westerly wind, envelope Rossby soliton and synoptic-scale waves) is found to be very similar to the observed Berggren-type blocking on the weather map(Berggren et al. 1949). The role of synoptic-scale eddies is to increase the amplitude of large-scale dipole anomaly flow, and to decrease its group velocity, phase velocity and zonal wavenumber so that the dipole anomaly system can be amplified and transferred from dispersive system to very weak dispersive one. This may explain why and how the synoptic-scale eddies can reinforce and maintain vortex pair block. Furthermore, it is clearly found that during the prevalence of the vortex pair block the synoptic-scale eddies are split into two branches around the vortex pair block due to the feedback of amplified dipole block. Key words Envelope Rossby solilon - Blocking - Synoptic-to-planetary scale interaction This research was supported jointly by the Foundation for University Key Teacher by the Ministry of Education and by the National Natural Science Foundation of China (49775266, 49905007)), the Knowledge Innovation Key Project of Chinese Academy of Sciences in the Resource Environment Field (Grant No. KZCX 2-203) and the National Key Foundation Research Project (G1998040900, Part I). 展开更多
关键词 Envelope Rossby solilon blocking Synoptic-to-planetary scale interaction
下载PDF
分组密码算法uBlock积分攻击的改进
19
作者 王晨 崔佳敏 +1 位作者 李木舟 王美琴 《电子与信息学报》 EI CAS CSCD 北大核心 2024年第5期2149-2158,共10页
积分攻击是由Daemen等人(doi:10.1007/BFb0052343)于1997年提出的一种密码分析方法,是继差分分析和线性分析之后最有效的密码分析方法之一。作为2018年全国密码算法设计竞赛分组算法的获胜算法,uB-lock抵抗积分攻击的能力受到较多的关... 积分攻击是由Daemen等人(doi:10.1007/BFb0052343)于1997年提出的一种密码分析方法,是继差分分析和线性分析之后最有效的密码分析方法之一。作为2018年全国密码算法设计竞赛分组算法的获胜算法,uB-lock抵抗积分攻击的能力受到较多的关注。为了重新评估uBlock家族密码算法抵抗积分攻击的安全性,该文利用单项式传播技术,结合混合整数线性规划(MILP)工具搜索积分区分器,并利用部分和技术进行密钥恢复攻击。对于uBlock-128/128和uBlock-128/256,基于搜索到的9轮积分区分器分别进行了首个11轮和12轮攻击,数据复杂度为2~(127)选择明文,时间复杂度分别为2~(127.06)和2~(224)次加密,存储复杂度分别为2~(44.58)和2~(138)字节;对于uBlock-256/256,基于搜索到的10轮积分区分器进行了首个12轮攻击,数据复杂度为2~(253)选择明文,时间复杂度为2~(253.06)次加密,存储复杂度为2~(44.46)字节。与之前uBlock的最优积分攻击结果相比,uBlock-128/128和uBlock-256/256的攻击轮数分别提高2轮,uBlock-128/256的攻击轮数提高3轮。本文的攻击说明,uBlock针对积分攻击依然有足够的安全冗余。 展开更多
关键词 密码分析 分组密码 ublock 积分攻击
下载PDF
Numerical Simulation of the Effect of the SST Anomalies in the Tropical Western Pacific on the Blocking Highs over the Northeastern Asia 被引量:7
20
作者 陆日宇 黄荣辉 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 1996年第4期411-424,共14页
The effects of the sea surface temperature (SST) anomalies in the tropical western Pacific on the atmospheric circulation anomalies over East Asia are simulated by the IAP-GCM with an observed and idealized distributi... The effects of the sea surface temperature (SST) anomalies in the tropical western Pacific on the atmospheric circulation anomalies over East Asia are simulated by the IAP-GCM with an observed and idealized distributions of the SST anomalies in the tropical western Pacific,respectively.Firstly,the atmospheric circulation anomalies during July and August,1980 are simulated by three anomalous experiments including the global SST anomaly experiment,the tropical SST anomaly experiment and the extratropical SST anomaly experiment,using the observed SST anomalies in 1980.It is shown that the SST anomalies in the tropical ocean greatly influence the formation and maintenance of the blocking high over the northeastern Asia,and may play a more important role than the SST anomalies in the extratropical ocean in the influence on the atmospheric circulation anomalies.Secondly,the effects of the SST anomalies in the tropical western Pacific on the atmospheric circulation anomalies over East Asia are also simulated with an idealized distribution of the SST anomalies in the tropical western Pacific.The simulated results show that the negative anomalies of SST in the tropical western Pacific have a significant effect on the formation and maintenance of the blocking high over the northeastern Asia. 展开更多
关键词 blocking high SST anomaly Atmospheric circulation anomaly
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部