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STRUCTURAL EFFECT IN FORKED CONJUGATIVE SYSTEMS——BIFURCATION-TYPE OF FORKED POLYENIC NITRILES,CARBOXYLIC ACIDS AND ESTERS
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作者 戴萃辰 岳振洁 蒋明谦 《Science China Chemistry》 SCIE EI CAS 1982年第10期1021-1034,共14页
Five homologous series of bifurcate systems of aliphatic and aromatic polyenic cyano andcarboxylic compounds have been prepared and studied. The electronic absorption spectra forthe series and the NMR chemical shifts ... Five homologous series of bifurcate systems of aliphatic and aromatic polyenic cyano andcarboxylic compounds have been prepared and studied. The electronic absorption spectra forthe series and the NMR chemical shifts for the methyl-, methylene- and beta-protons havebeen found to conform very well to the rule of homologous linearity. The mass spectra forthe α-cyano polyenic ester series show strong peaks for the fragments of M-COOEt but noneof M-CN, indicating that the CN group seems to be in stronger conjugation with the poly-enic chain than the COOEt group does. In all the forked series studided, a red shift in electronic spectra is brought about upon theintroduction of an electron-attractive branching group, just like the case of introducing anelectron-repelling substituent. This has been taken as an indication of the predominance of themolecular integrality over the group characteristics. By means of the method of similar triangles between a homologous line for a linearseries and that for the 展开更多
关键词 OCH BIFURCATION-TYPE OF forked POLYENIC NITRILES CARBOXYLIC ACIDS AND ESTERS STRUCTURAL EFFECT IN forked CONJUGATIVE SYSTEMS CNY
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A new modified forked flap and a reverse V shaped flap for secondary correction of bilateral cleft lip nasal deformities 被引量:2
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作者 YAN Wei ZHAO Zhen-min YIN Ning-bei SONG Tao LI Hai-dong WU Di GAO Feng WANG Xin-gang 《Chinese Medical Journal》 SCIE CAS CSCD 2011年第23期3993-3996,共4页
Background The columella, nasal tip, lip relationship in the bilateral cleft lip nasal deformity remains a great challenge for plastic surgeon. An esthetically satisfying result is difficult to obtain. A subset of pat... Background The columella, nasal tip, lip relationship in the bilateral cleft lip nasal deformity remains a great challenge for plastic surgeon. An esthetically satisfying result is difficult to obtain. A subset of patients with bilateral cleft lip nasal deformity still require columellar lengthening and nasal correction and philtrial construction. This study aimed to provide a new method based on the forked flap to improve the final appearance of these patients. Methods A technique to correct this deformity is described. This consists of (1) a newly modified forked flap including the orbicularis oris muscle and nasalis muscle along the whole flap for columellar lengthening, (2) a reverse V shaped flap from the lower portion of the columella and the prolabium for normal size phitrum construction, (3) inserting the vermilion portion of the forked flap and advancing the nasal floor medially and anteriorly to lengthen and maintain the nasal septum side of the columella for proper tip positioning, (4) open rhinoplasty, allowing definitive repositioning of the lower lateral cartilages, (5) reconstruction of the orbicularis orismuscle as required, and (6) the flaring nostril floor advancing medially and constructing the sill. Results This technique was applied to 15 cases of secondary bilateral cleft lip nasal deformity. All the flaps took without signs of partial necrosis. In all cases, the nasal tip was projected forward with adequate columella elongation, and the height of the prolabium was added with normal size philtrial dimensions. Conclusions This method makes maximum use of the tissue containing the scar in the lip and limits tissues in the lower portion of the columella and the prolabium for adequate columella elongation and reconstruction with normal size philtrial dimensions. It is a very reasonable and useful method in correction of secondary bilateral cleft lip nasal deformities. 展开更多
关键词 secondary bilateral cleft lip nasal deformity COLUMELLA philtrum forked flap reverse V shaped flap
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Application and efficacy of reconstructing forked corpus spongiosum in distal/midshaft hypospadias repair 被引量:1
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作者 Bin Zhang Yun-Li Bi Shuang-Sui Ruan 《Asian Journal of Andrology》 SCIE CAS CSCD 2021年第1期47-51,共5页
We reviewed our experience in reconstructing forked corpus spongiosum(FCS)in distal/midshaft hypospadias repair and analyzed the efficacy of this surgical technique.From August 2013 to December 2018,137 consecutive ca... We reviewed our experience in reconstructing forked corpus spongiosum(FCS)in distal/midshaft hypospadias repair and analyzed the efficacy of this surgical technique.From August 2013 to December 2018,137 consecutive cases of distal/midshaft hypospadias operated by the same surgeon in Urology Department,Children’s Hospital of Fudan University(Shanghai,China),were retrospectively analyzed.Sixty-four patients who underwent routine tubularized incised plate(TIP)or onlay island flap(ONLAY)surgery were included in the nonreconstructing group,and 73 patients who underwent reconstructing FCS during TIP or ONLAY surgery were included as the reconstructing group.Thirty-eight cases underwent TIP,and 26 underwent ONLAY in the nonreconstructing group,with a median follow-up of 44(range:30-70)months.Twenty-seven cases underwent TIP,and 46 underwent ONLAY in the reconstructing group,with a median follow-up of 15(range:6-27)months.In the nonreconstructing/reconstructing groups,the mean age at the time of surgery was 37.55(standard deviation[s.d.]:29.65)/35.23(s.d.:31.27)months,the mean operation duration was 91.95(s.d.:12.17)/93.84(s.d.:14.91)min,the mean neourethral length was 1.88(s.d.:0.53)/1.94(s.d.:0.53)cm,and the mean glans width was 11.83(s.d.:1.32)/11.56(s.d.:1.83)mm.Twelve(18.8%)/5(6.8%)postoperative complications occurred in the nonreconstructing/reconstructing groups.These included fistula(5/2),glans dehiscence(3/0),diverticulum(1/2),residual chordee(3/0),and meatus stenosis(0/1)in each group.There was a significant difference in the overall rate of complications(P=0.035).These results indicate that the technique of reconstructing FCS provides excellent outcomes with fewer complications in distal/midshaft hypospadias repair. 展开更多
关键词 COMPLICATIONS distal/midshaft hypospadias forked corpus spongiosum glans tilt
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A highly sensitive LITES sensor based on a multi-pass cell with dense spot pattern and a novel quartz tuning fork with low frequency
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作者 Yahui Liu Shunda Qiao +4 位作者 Chao Fang Ying He Haiyue Sun Jian Liu Yufei Ma 《Opto-Electronic Advances》 SCIE EI CAS CSCD 2024年第3期26-34,共9页
A highly sensitive light-induced thermoelectric spectroscopy(LITES)sensor based on a multi-pass cell(MPC)with dense spot pattern and a novel quartz tuning fork(QTF)with low resonance frequency is reported in this manu... A highly sensitive light-induced thermoelectric spectroscopy(LITES)sensor based on a multi-pass cell(MPC)with dense spot pattern and a novel quartz tuning fork(QTF)with low resonance frequency is reported in this manuscript.An erbi-um-doped fiber amplifier(EDFA)was employed to amplify the output optical power so that the signal level was further enhanced.The optical path length(OPL)and the ratio of optical path length to volume(RLV)of the MPC is 37.7 m and 13.8 cm^(-2),respectively.A commercial QTF and a self-designed trapezoidal-tip QTF with low frequency of 9461.83 Hz were used as the detectors of the sensor,respectively.The target gas selected to test the performance of the system was acetylene(C2H2).When the optical power was constant at 1000 mW,the minimum detection limit(MDL)of the C2H2-LITES sensor can be achieved 48.3 ppb when using the commercial QTF and 24.6 ppb when using the trapezoid-al-tip QTF.An improvement of the detection performance by a factor of 1.96 was achieved after replacing the commer-cial QTF with the trapezoidal-tip QTF. 展开更多
关键词 light-induced thermoelectric spectroscopy quartz tuning fork multi-pass cell gas sensing
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HeI Photoelectron Spectroscopic Study ofthe Electronic Structure in Some ForkedConjugative Systems
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作者 王殿勋 郑世钧 +4 位作者 蔡新华 孟令鹏 戴萃辰 徐广智 J.B.Peel 《Chinese Science Bulletin》 SCIE EI CAS 1994年第5期391-396,共6页
1 Introduction It has been known from the experiment that two conjugated systems of aromaticheterocyclic carbonyl and phenyl carbonyl groups in the aromatic heterocylic phenylketone compounds are not equivalent and so... 1 Introduction It has been known from the experiment that two conjugated systems of aromaticheterocyclic carbonyl and phenyl carbonyl groups in the aromatic heterocylic phenylketone compounds are not equivalent and so are not coplanary. The synhesis 展开更多
关键词 gas phase HEL PHOTOELECTRON spectroscopy forked conjngated COMPOUNDS MNDO calculation.
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Ground-Tracking With a Forked Tongue
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《当代外语研究》 1995年第7期19-19,共1页
Scientists since Aristotle’s day have wondered why the tongues of snakes and many lizards——are forked, a trait that dates from at least the Cretaceous,more than 65 million years ago.Now Kurt Schwenk,a University of... Scientists since Aristotle’s day have wondered why the tongues of snakes and many lizards——are forked, a trait that dates from at least the Cretaceous,more than 65 million years ago.Now Kurt Schwenk,a University of Connecticut evolutionary biologist, thinks he knows the answer. "It gives them the abil- 展开更多
关键词 In Ground-Tracking With a forked Tongue
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Electrode design for multimode suppression of aluminum nitride tuning fork resonators
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作者 Yi Yuan Qingrui Yang +6 位作者 Haolin Li Shuai Shi Pengfei Niu Chongling Sun Bohua Liu Menglun Zhang Wei Pang 《Nanotechnology and Precision Engineering》 EI CAS CSCD 2023年第4期11-21,共11页
This paper is focused on electrode design for piezoelectric tuning fork resonators.The relationship between the performance and electrode pattern of aluminum nitride piezoelectric tuning fork resonators vibrating in t... This paper is focused on electrode design for piezoelectric tuning fork resonators.The relationship between the performance and electrode pattern of aluminum nitride piezoelectric tuning fork resonators vibrating in the in-plane flexural mode is investigated based on a set of resonators with different electrode lengths,widths,and ratios.Experimental and simulation results show that the electrode design impacts greatly the multimode effect induced from torsional modes but has little influence on other loss mechanisms.Optimizing the electrode design suppresses the torsional mode successfully,thereby increasing the ratio of impedance at parallel and series resonant frequencies(R_(p)/R_(s))by more than 80%and achieving a quality factor(Q)of 7753,an effective electromechanical coupling coefficient(kt_(eff)^(2))of 0.066%,and an impedance at series resonant frequency(R_(m))of 23.6 kΩ.The proposed approach shows great potential for high-performance piezoelectric resonators,which are likely to be fundamental building blocks for sensors with high sensitivity and low noise and power consumption. 展开更多
关键词 Tuning fork MULTIMODE AlN-based resonator Microelectromechanical systems
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基于Fork/Join的事务日志伴随模式挖掘方法
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作者 孔明 魏东 +1 位作者 冉义兵 毕国鹏 《小型微型计算机系统》 CSCD 北大核心 2023年第2期239-247,共9页
信息系统产生的大量事务日志数据蕴含着潜在的伴随模式,伴随模式是指在时空上频繁共现的一组对象.由于传统的滑动窗口算法和FP-Growth算法只能调用单一线程进行计算,随着数据规模的扩张,会导致挖掘伴随模式的时间急剧增加.为此本文提出... 信息系统产生的大量事务日志数据蕴含着潜在的伴随模式,伴随模式是指在时空上频繁共现的一组对象.由于传统的滑动窗口算法和FP-Growth算法只能调用单一线程进行计算,随着数据规模的扩张,会导致挖掘伴随模式的时间急剧增加.为此本文提出了一种基于Fork/Join并行技术的伴随模式挖掘框架,其能够实现从单线程到多线程的迁移,充分利用多核配置的加速性能.该框架由划定伴随数据集、频繁项集挖掘和关联规则挖掘三部分组成.首先,提出了基于Fork/Join的多核并行滑动窗口算法,以缩短从事务日志中划定伴随数据集的时间;然后,提出基于Fork/Join的多核并行FP-Growth算法,以并行地挖掘伴随数据集中的频繁项集;最后,引入支持度、置信度和提升度3个参数,对伴随模式中各对象间的关联规则进行挖掘.基于门禁刷卡数据的实验结果表明,相比传统算法,本文所提出的框架能够挖掘出更多的伴随模式,同时挖掘效率较高. 展开更多
关键词 事务日志 伴随模式 Fork/Join框架 滑动窗口 FP-GROWTH算法
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Use of the 1893 Cranberry, North Carolina Topographic Map to Determine Blue Ridge Escarpment Area Drainage System and Erosional Landform Origins, USA
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作者 Eric Clausen 《Open Journal of Geology》 2023年第11期1220-1239,共20页
A new and fundamentally different geology and glacial history paradigm (new paradigm) is used to interpret previously ignored and unexplained drainage system and erosional landform evidence shown on the 1893 United St... A new and fundamentally different geology and glacial history paradigm (new paradigm) is used to interpret previously ignored and unexplained drainage system and erosional landform evidence shown on the 1893 United States Geological Survey Cranberry, North Carolina 1:125,000 scale topographic map (which has a 100-foot or about a 30-meter contour interval). In most regions including the Cranberry map area, geomorphologists have never been able to use the accepted geology and glacial history paradigm (accepted paradigm) to explain most of the topographic map drainage system and erosional landform evidence. Probably for that reason, drainage system and erosional landform evidence shown on the 1893 Cranberry topographic map and its adjacent topographic maps has been ignored for 130 years. This study demonstrates how a new geology and glacial history paradigm (new paradigm) which was developed by using Great Plains and Rocky Mountain topographic map evidence explains the 1893 Cranberry map drainage system and erosional landform evidence (and similar evidence from a small area on the adjacent 1905 Morgantown map). The new paradigm sees the Cranberry map area as being located along the southeastern rim of a continental ice sheet created and occupied deep “hole” with regional erosion occurring and present-day drainage systems developing when the headward erosion of southeast-oriented valleys from the Atlantic Ocean and of northwest-oriented valleys from the developing deep “hole” into the gradually rising deep “hole” rim captured massive and prolonged south- and southwest-oriented meltwater floods. The new paradigm permits explanations for most drainage divides, named and unnamed gaps, barbed tributaries, through valleys extending across drainage divides, isolated erosional remnants, diverging and converging valleys, and unusual river and stream direction changes which the 1893 Cranberry topographic map shows. 展开更多
关键词 Eastern Continental Divide Geomorphology Linville Gap South Fork New River Yadkin River Watauga River
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Compensation of Parasitic Capacitance of Quartz Tuning Fork in AFM
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作者 Yidai Liu 《Journal of Applied Mathematics and Physics》 2023年第5期1404-1413,共10页
We have built an atomic force microscope using a quartz tuning fork as sensor. The excitation method we adopted, the electrical excitation, introduces stray capacitance into the signal-processing circuit. In this repo... We have built an atomic force microscope using a quartz tuning fork as sensor. The excitation method we adopted, the electrical excitation, introduces stray capacitance into the signal-processing circuit. In this report, we demonstrated a simple but effective method to compensate for this parasitic capacitance by adding a compensator circuit consisting of an inverting amplifier and a capacitor. The capacitor is connected in series with the inverting amplifier and the compensator is connected in parallel with the quartz tuning fork. The resonance curve of the system measured after adding the homemade compensator resembles that of a pure RLC circuit, meaning that the stray capacitance is successfully eliminated. Furthermore, we tried to use our equipment to measure PDMS sample and got clean data. This system can be further combined with confocal microscope and diamond with NV defect to build scanning NV magnetometry. 展开更多
关键词 Atomic Force Microscope Quartz Tuning Fork Stray Capacitance Compensator Circuit PDMS Sample
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祁连山区冰沟流域积雪分布特征及其属性观测分析 被引量:35
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作者 郝晓华 王建 +6 位作者 车涛 张璞 梁继 李弘毅 李哲 白云洁 白艳芬 《冰川冻土》 CSCD 北大核心 2009年第2期284-292,共9页
以祁连山冰沟流域为研究区,通过在流域内布设花杆观测积雪深度,调查了山区积雪分布情况;利用雪特性分析仪测量了区内积雪密度、介电常数、液态水含量等积雪参数,光谱仪测量了不同类型积雪的光谱特征,手持反照率测量计观测积雪表面反照率... 以祁连山冰沟流域为研究区,通过在流域内布设花杆观测积雪深度,调查了山区积雪分布情况;利用雪特性分析仪测量了区内积雪密度、介电常数、液态水含量等积雪参数,光谱仪测量了不同类型积雪的光谱特征,手持反照率测量计观测积雪表面反照率,带刻度手持放大镜测量积雪粒径,红外温度计和针式温度计测量雪层的温度和实地测量积雪属性.同时,在研究区内选择加强观测区挖雪坑,对雪层内部属性和雪剖面分层特性作了进一步研究,计算了流域内积雪等效密度;最后对试验中所使用的野外实测积雪的各种方法进行了评价.研究表明:山区积雪分布很不均匀,在阴坡山谷雪深最深,阳坡雪积累最少,即使在同一样区,积雪分布也不均匀;研究区的积雪属于潮雪,体积含水量在3%以下;不同粒径、类型和表面粗糙度的积雪反射率不同,验证了积雪光谱是雪颗粒、污染物和地面粗糙度的函数;积雪反照率随太阳高度角升高逐步降低,在没有新降雪的情况下,日反照率也逐渐降低;雪分层比较明显,雪下冰晶层发育良好.当深度达到20 cm时,积雪具有保温作用;冰沟流域的积雪等效密度随时间和空间变化不大,经计算为0.16 g.cm-3. 展开更多
关键词 冰沟流域 积雪分布特征 积雪属性 SNOW FORK 积雪等效密度
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阿尔泰山融雪期不同下垫面积雪特性观测与分析研究 被引量:24
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作者 张伟 沈永平 +4 位作者 贺建桥 贺斌 努尔兰.哈再孜 吴雪娇 王国亚 《冰川冻土》 CSCD 北大核心 2014年第3期491-499,共9页
2014年3月融雪期间在阿尔泰山额尔齐斯河河源区,基于已有的气象和积雪(雪深、雪密度)观测,利用Snow Fork雪特性仪和便携式温度计TP3001,选择草地、水泥地和河冰三种不同的下垫面分别观测了分层积雪密度、液态水含量和雪层温度变化.结果... 2014年3月融雪期间在阿尔泰山额尔齐斯河河源区,基于已有的气象和积雪(雪深、雪密度)观测,利用Snow Fork雪特性仪和便携式温度计TP3001,选择草地、水泥地和河冰三种不同的下垫面分别观测了分层积雪密度、液态水含量和雪层温度变化.结果表明:三种下垫面上表层积雪的温度、液态水含量和密度变化规律基本一致.积雪特性的差异主要体现在积雪层底部,河冰和草地与积雪接触面温度日变化过程呈现出"单峰型",而与水泥地接触面上的温度日变化呈现出"双峰型";河冰上积雪底部的液态水含量最小且日变化幅度较小,草地次之,水泥上积雪底部液态水含量的波动最大;水泥和草地上底部积雪的密度变化趋势一致,为密实化过程,而河冰上积雪底部的积雪因深霜层的形成致使雪密度逐渐减小.对同一下垫面上的积雪而言,水泥和草地上积雪温度的极大值出现在雪层中间,河冰上雪层的温度廓线沿雪深有波动上升的趋势,最大值出现在积雪与河冰的接触面处.三种下垫面上积雪的液态水含量最大值均出现在中间雪层,雪密度均呈现沿雪深增加而递减的变化趋势.液态水含量受积雪温度的控制,当积雪温度低于-3℃时,积雪中的液态水可以忽略不计;当积雪温度低于-1℃时,积雪的液态水含量低于1%;当积雪温度大于-1℃时,积雪中出现液态水的比例显著增加,且液态水含量的波动范围较大,最高可到6.2%. 展开更多
关键词 阿尔泰山 季节性积雪 雪密度 液态水含量 积雪温度 Snow FORK
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大规模电力系统潮流转移比多核并行批处理方法 被引量:9
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作者 罗彬 李刚 +3 位作者 苗树敏 程春田 吴琛 王森 《中国电机工程学报》 EI CSCD 北大核心 2015年第21期5446-5454,共9页
实现各类预想故障下潮流转移比快速仿真分析是电网安全稳定运行的重要保证。针对现有实际运行方式中潮流转移分析困难问题,提出大规模电力系统潮流转移比多核并行批处理方法。该方法基于广泛使用的商业大系统分析工具,在参数解析分类、... 实现各类预想故障下潮流转移比快速仿真分析是电网安全稳定运行的重要保证。针对现有实际运行方式中潮流转移分析困难问题,提出大规模电力系统潮流转移比多核并行批处理方法。该方法基于广泛使用的商业大系统分析工具,在参数解析分类、故障自动设置及结果解析的基础上,引入深度优先搜索(depth first search,DFS)算法进行孤立节点和孤岛区域检测以保证网络完整性,结合潮流计算合理性的自动判别以实现潮流转移比的批处理分析;同时在多核环境下,构建基于Fork/Join的并行框架,采用"分治模式"递归分解计算任务,从而实现分析方法的多核并行。算例仿真和在云南电网的实际应用验证了所提方法的有效性和快速性。 展开更多
关键词 潮流转移 深度优先搜索 多核并行 Fork/Join框架 PSD-BPA
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基于任务复制的调度算法 被引量:10
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作者 张建军 李庆华 瞿勇 《计算机工程与设计》 CSCD 北大核心 2009年第8期1896-1899,2029,共5页
任务调度是并行分布式计算系统中最具挑战性的NP完全问题之一。基于任务复制的调度是一种有效的调度方法。在通信开销较小的情况下,现已有许多算法能产生最优调度。但其最优条件要么比较苛刻,要么比较复杂。因此,针对这些算法存在的问题... 任务调度是并行分布式计算系统中最具挑战性的NP完全问题之一。基于任务复制的调度是一种有效的调度方法。在通信开销较小的情况下,现已有许多算法能产生最优调度。但其最优条件要么比较苛刻,要么比较复杂。因此,针对这些算法存在的问题,提出一个新的基于任务复制的聚集调度(TDCS)算法,不仅其最优条件简单、宽松,而且该算法具有更小的时间复杂度O(log),其中,和分别表示任务集中任务的个数和最大入度。 展开更多
关键词 最优调度算法 任务复制 最优条件 任务聚集 Fork—Join任务图
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调度Fork-Join任务图的贪心算法 被引量:6
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作者 杨斌 张建军 杨峰 《计算机工程与设计》 CSCD 北大核心 2008年第15期3864-3866,3894,共4页
任务调度算法的目标是把组成并行程序的一组任务分配到多个处理器以使得程序的完成时间最短,这是一个NP完全问题。虽然许多算法在任务满足某些条件时能产生最优调度,但大多都忽略了节省处理器个数和最小化程序总的完成时间等问题。Fork-... 任务调度算法的目标是把组成并行程序的一组任务分配到多个处理器以使得程序的完成时间最短,这是一个NP完全问题。虽然许多算法在任务满足某些条件时能产生最优调度,但大多都忽略了节省处理器个数和最小化程序总的完成时间等问题。Fork-Join结构是一种并行处理的基本结构。因此,专门针对Fork-Join任务图,提出了一个能产生最优调度的新的贪心调度算法,该算法具有高的加速比和总体效率,时间复杂度为2,其中,表示任务集中任务的个数。实验结果表明,相比其它算法,该算法具有较短的调度长度、较短的完成时间,使用的处理器数较少。 展开更多
关键词 最优调度算法 任务复制 Fork—Join任务图 关键任务 加速比
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Forking引理与一类基于身份签名体制的安全性证明(英文) 被引量:4
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作者 顾纯祥 祝跃飞 潘晓豫 《软件学报》 EI CSCD 北大核心 2007年第4期1007-1014,共8页
在随机谕示模型下,研究一类基于身份的签名体制(称为基于身份的一般签名体制)的安全性.所得理论成果可以被看作Pointcheval和Stern提出的Forking引理在基于身份签名体制研究领域的扩展,有助于理解和简化一些现有的基于身份签名体制的安... 在随机谕示模型下,研究一类基于身份的签名体制(称为基于身份的一般签名体制)的安全性.所得理论成果可以被看作Pointcheval和Stern提出的Forking引理在基于身份签名体制研究领域的扩展,有助于理解和简化一些现有的基于身份签名体制的安全性证明,如Cha-Cheon的体制、Hess的体制1及Cheon-Kim-Yoon的体制等. 展开更多
关键词 基于身份的签名 Forking引理 可证安全 存在性伪造
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Dalvik虚拟机进程模型分析 被引量:18
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作者 周毅敏 陈榕 《计算机技术与发展》 2010年第2期83-86,共4页
Android手机操作系统是Google于2008年推出的智能手机操作系统,它的所有应用都是基于Java语言的,它的类Java虚拟机Dalvik提供了所有应用的运行时环境。Dalvik是一个面向Linux作为嵌入式操作系统设计的虚拟机,尤其是它的面向进程的设计,... Android手机操作系统是Google于2008年推出的智能手机操作系统,它的所有应用都是基于Java语言的,它的类Java虚拟机Dalvik提供了所有应用的运行时环境。Dalvik是一个面向Linux作为嵌入式操作系统设计的虚拟机,尤其是它的面向进程的设计,充分利用了Linux进程管理的特点。介绍了Dalvik所依赖的基础,即Linux操作系统内核中进程管理的一些特性和传统Java程序对进程的控制;进而论述了Dalvik的进程模型的特点,从API和本地代码两个层面具体阐述了进程运行、创建和之间通信的部分细节。文中旨在为Dalvik的研究和应用提供参考。 展开更多
关键词 Dalvik 虚拟机 结合子 FORK 写时复制
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面向Fork/Join框架的软件重构及性能分析 被引量:2
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作者 张冬雯 柳晨光 张杨 《计算机应用》 CSCD 北大核心 2015年第11期3172-3177,共6页
针对目前对于Fork/Join框架应用和性能分析的相关工作还不多的现状,以JGF基准测试程序套件为基础,对其中的series、crypt、sparsematmult和sor等程序使用Fork/Join框架进行重构,并以series程序为例,详细地说明了重构的过程。在实验中,首... 针对目前对于Fork/Join框架应用和性能分析的相关工作还不多的现状,以JGF基准测试程序套件为基础,对其中的series、crypt、sparsematmult和sor等程序使用Fork/Join框架进行重构,并以series程序为例,详细地说明了重构的过程。在实验中,首先,测试了每个程序在不同阈值下使用Fork/Join框架分别递归1、2、3次执行程序的时间,进而选择相对较好的阈值;然后,对每个程序使用Fork/Join框架和使用Thread的执行时间进行了对比;此外,测试了重构后的程序在执行过程中任务窃取的情况。实验结果表明,Fork/Join框架执行时间与多线程执行时间相比,平均降低了14.2%;对于series程序,当数据大小为size C且线程个数为2时,Fork/Join框架执行时间比多线程执行时间降低高达40%,可见,在多核处理器平台上应用Fork/Join框架比使用多线程将获得更好的性能。 展开更多
关键词 Fork/Join框架 软件重构 工作窃取 性能分析
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LL-Ⅲ模型在美国Baron Fork流域的应用 被引量:1
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作者 赵英虎 李兰 +2 位作者 周浩澜 杨超 武见 《人民长江》 北大核心 2008年第6期46-48,共3页
有物理基础的流域分布式水文模型对流域产汇流以及对洪水过程的模拟与预报一直是水文研究的重点。分析了美国Baron Fork流域的降雨产汇流特性,应用基于DEM的LL-Ⅲ水文模型对Baron Fork流域进行产汇流模拟及洪水预报,结果表明,从模型模... 有物理基础的流域分布式水文模型对流域产汇流以及对洪水过程的模拟与预报一直是水文研究的重点。分析了美国Baron Fork流域的降雨产汇流特性,应用基于DEM的LL-Ⅲ水文模型对Baron Fork流域进行产汇流模拟及洪水预报,结果表明,从模型模拟精度来看,该水文模型在Baron Fork流域洪水预报、流量模拟应用中取得了较好的效果,可以在水文、地质、地貌、气候等方面与该地区类似的流域推广。 展开更多
关键词 流域数字化 DEM水文分析 分布式水文模型 Baron FORK
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广义Fork-Join任务图的调度问题研究 被引量:2
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作者 杨峰 张建军 《兵工自动化》 2009年第12期37-40,共4页
Fork-Join结构是一种并行处理的基本结构。为处理传统方法难以解决的复杂和非线性问题,缩短整个程序的总完成时间,针对广义Fork-Join任务图提出了基于遗传算法的调度算法,该算法将遗传算法和任务复制相结合,有效地缩短了得到最优结果的... Fork-Join结构是一种并行处理的基本结构。为处理传统方法难以解决的复杂和非线性问题,缩短整个程序的总完成时间,针对广义Fork-Join任务图提出了基于遗传算法的调度算法,该算法将遗传算法和任务复制相结合,有效地缩短了得到最优结果的时间。实验结果表明,与其他算法相比,该算法具有较短的调度长度。 展开更多
关键词 任务调度 任务复制 遗传算法 广义Fork—Join任务图
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