检索结果-南通市图书馆

Cooperative DVB-SH Satellite Broadcasting Systems with Rotated Signal Constellations

China Communications 2015年第6期12卷 59-72页

作者： nikos C.Sagias Stylianos Papaharalabos P.Takis Mathiopoulos Department of Informatics and Telecommunications University of Peloponnese Laboratory of Wireless Communications Institute of Informatics and TelecommunicationsNational Centre for Scientific Research"Demokritos" Patriarhou Grigoriou and Neapoleos streetAgia Paraskevi15 310 AthensGreece Department of Informatics and Telecommunications University of Athens

In this paper,we study the advantages of cooperation in broadcasting systems from a geosynchronous earth orbit(GEO)satellite to mobile terminals(MTs),achieved through a terrestrial complementary ground station(CGS) with fixed installment,which acts as a relay.Moreover and in the context of the digital video broadcasting-satellite-to-handheld(DVB-SH) standard,the performance improvements offered by the rotated constellations method are investigated,where prior transmission,a phase rotation of the transmitted symbols by a fixed angle is applied followed by a random component interleaver.Turbo codes with soft decision decoding and appropriate random channel interleavers are also considered.We present analytical expressions for the bit log-likelihood ratios(LLRs)that are needed for soft decision decoding at the MT turbo decoder,while the code combining technique is adapted to improve the end-to-end(E2E) performance.Then,we obtain through extensive computer simulations the average bit error probability(ABEP) of quadrature phase-shift keying(QPSK) signals received over pure land-mobile satellite(LMS)and pure CGS links for coding rates 1/3 and6/7.Moreover,the optimal rotation angles are obtained for both links.E2 E ABEP results are then presented assuming cooperation between GEO and CGS,while the power allocation issue is investigated under fixed total transmission power.Our performance evaluation results show that by using the constellation rotation technique,a performance gain can be achieved for high coding rates.

关键词：卫星广播系统相位旋转卫星信号星座图合作性地球同步轨道软判决译码性能评价

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Growth of Niobium Thin Films on Si Substrates by Pulsed Nd:YAG Laser Deposition

引用

Journal of Materials Science & Technology 2015年第8期31卷 784-789页

作者： Francisco Gontad Antonella Lorusso Luigi Solombrino loannis Koutselas nikos Vainos Alessio Perrone Department of Mathematics and Physics "E.De Giorgi" and National Institute of Nuclear PhysicsUniversity of Salento Department of Materials Science University of Patras

The growth of Nb thin films on Si（100） substrates by different laser fluences （4-15 J/cm2） was reported, The pulsed Nd：YAG laser deposition （PLD） under influence of laser fluence on ablation rate and deposition rate was discussed. X-ray diffraction （XRD） investigations of the deposited films showed an amorphous structure. The droplet density on the film surface observed by scanning electron microscopy （SEM） analyses was extremely low. It was experimentally proved that the droplets on the film surface originated from liquid phase on the target surface, Profilometric measurements of the deposited Nb films revealed a substantial asymmetry in the film thickness related to the plume deflection effect. The measured electrical resistivity of the Nb film was higher than that of high purity Nb bulk. The present investigations of ablation and deposition process of Nb thin films are related to its potential application in superconducting radio-frequency （SRF） cavities.

关键词： Pulsed laser deposition Nb thin films Ablation and deposition rate

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The use of hydrogel-delivered extracellular vesicles in recovery of motor function in stroke:a testable experimental hypothesis for clinical translation including behavioral and neuroimaging assessment approaches

引用

Neural Regeneration Research 2021年第4期16卷 605-613页

作者： Magdalini Tsintou Kyriakos Dalamagkas Tara LMoore Yogesh Rathi Marek Kubicki Douglas LRosene nikos Makris Departments of Psychiatry and Neurology Services Center for Neural Systems InvestigationsCenter for Morphometric AnalysisAthinoula A.Martinos Center for Biomedical ImagingMassachusetts General HospitalHarvard Medical SchoolBostonMAUSA Department of Psychiatry Psychiatry Neuroimaging LaboratoryBrigham and Women’s HospitalHarvard Medical SchoolBostonMAUSA University College of London Division of Surgery&Interventional Science Center for Nanotechnology&Regenerative MedicineUniversity College LondonLondonUK Department of Physical Medicine and Rehabilitation The University of Texas Health Science Center at HoustonHoustonTXUSA The Institute for Rehabilitation and Research Memorial Hermann Research Center The Institute for Rehabilitation and Research Memorial Hermann HospitalHoustonTXUSA Department of Anatomy&Neurobiology Boston University School of MedicineBostonMAUSA

Neural tissue engineering,nanotechnology and neuroregeneration are diverse biomedical disciplines that have been working together in recent decades to solve the complex problems linked to central nervous system(CNS)repair.It is known that the CNS demonstrates a very limited regenerative capacity because of a microenvironment that impedes effective regenerative processes,making development of CNS therapeutics challenging.Given the high prevalence of CNS conditions such as stroke that damage the brain and place a severe burden on afflicted individuals and on society,it is of utmost significance to explore the optimum methodologies for finding treatments that could be applied to humans for restoration of function to pre-injury levels.Extracellular vesicles(EVs),also known as exosomes,when derived from mesenchymal stem cells,are one of the most promising approaches that have been attempted thus far,as EVs deliver factors that stimulate recovery by acting at the nanoscale level on intercellular communication while avoiding the risks linked to stem cell transplantation.At the same time,advances in tissue engineering and regenerative medicine have offered the potential of using hydrogels as bio-scaffolds in order to provide the stroma required for neural repair to occur,as well as the release of biomolecules facilitating or inducing the reparative processes.This review introduces a novel experimental hypothesis regarding the benefits that could be offered if EVs were to be combined with biocompatible injectable hydrogels.The rationale behind this hypothesis is presented,analyzing how a hydrogel might prolong the retention of EVs and maximize the localized benefit to the brain.This sustained delivery of EVs would be coupled with essential guidance cues and structural support from the hydrogel until neural tissue remodeling and regeneration occur.Finally,the importance of including nonhuman primate models in the clinical translation pipeline,as well as the added benefit of multi-modal neuroimaging analysis to establish no

关键词： cortical injury exosomes extracellular vesicles hydrogels neural tissue engineering neural tissue repair neuroregeneration non-human primates stroke

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Simulating geometrically complex blast scenarios

引用

Defence Technology（防务技术） 2016年第2期12卷 134-146页

作者： Ian G.CULLIS nikos NIKIFORAKIS Peter FRANKL Philip BLAKELY Paul BENNETT Paul GREENWOOD QinetiQ Fort Halstead Sevenoaks Kent T N14 7BP UK Cavendish Laboratory Cambridge University Cambridge CB30LH UK Cambridge Numerical Solutions Ltd Ely Cambridge CB7 5NE UK

The effects of blast waves generated by energetic and non-energetic sources are of continuing interest to the ballistics research community.Modern conflicts are increasingly characterised by asymmetric urban warfare, with improvised explosive devices(IEDs) often playing a dominant role on the one hand and an armed forces requirement for minimal collateral effects from their weapons on the other. These problems are characterised by disparate length- and time-scales and may also be governed by complex physics. There is thus an increasing need to be able to rapidly assess and accurately predict the effects of energetic blast in topologically complex scenarios. To this end, this paper presents a new Qineti Q-developed advanced computational package called EAGLE-Blast, which is capable of accurately resolving the generation, propagation and interaction of blast waves around geometrically complex shapes such as vehicles and buildings. After a brief description of the numerical methodology, various blast scenario simulations are described and the results compared with experimental data to demonstrate the validation of the scheme and its ability to describe these complex scenarios accurately and efficiently. The paper concludes with a brief discussion on the use of the code in supporting the development of algorithms for fast running engineering models.

关键词：爆炸装置复杂场景场景模拟能量来源武装部队时间尺度相互作用形状复杂

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

面向多场景辅助服务的大规模电动汽车聚合可调度容量建模

引用

电力系统自动化 2023年

作者：王杨洋茆美琴杨铖周堃杜燕 nikos D.HATZIARGYRIOU 合肥工业大学电气与自动化工程学院国网安徽省电动汽车服务有限公司国网安徽省电力有限公司雅典国立理工大学

大规模电动汽车（electric vehicle EV）聚合可调度容量（aggerated schedulable capacity, ASC）是含EV的虚拟电厂参与多层级多场景电力平衡辅助服务的重要技术指标之一。然而现有电动汽车ASC模型难以适应大规模电动汽车与省级电力调... 详细信息

大规模电动汽车（electric vehicle EV）聚合可调度容量（aggerated schedulable capacity, ASC）是含EV的虚拟电厂参与多层级多场景电力平衡辅助服务的重要技术指标之一。然而现有电动汽车ASC模型难以适应大规模电动汽车与省级电力调度中心互动场景。为此，文中从面向电力系统调峰、调频和调压多级多场景调控新视角，提出了数据驱动和机器学习相结合的双层聚类ASC建模方法。该方法通过构建EV-充电桩广义储能单元的个体可调度容量模型，结合基于密度空间的聚类算法和改进的自组织映射深度聚类算法，从而有效地融合了EV电量的时间分布和充电桩的空间分布特性，构建了面向调峰、调频和调压多场景调控的ASC模型。采用了某省数百万条实际充电纪录数据对提出的方法进行了验证，获得了“早间型”、“中午型”、“晚间型”等多种充电画像类型，实现了时空分布各异的EV广义储能系统的自主聚合和省市级规模EV参与电网不同辅助服务潜能的评估，并为ASC的预测奠定了数据基础。

关键词：电动汽车辅助服务数据驱动广义储能系统 V2G 可调度容量聚合模型双层聚类

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

A C2-symmetric triple [5]helicene based on N-annulated triperylene hexaimide for chiroptical electronics

引用

Science China Chemistry 2020年第2期63卷 208-214页

作者： Zetong Ma Thorsten Winands Ningning Liang Dong Meng Wei Jiang nikos L.Doltsinis Zhaohui Wang CAS Research/Education Center for Excellence in Molecular Sciences Institute of ChemistryChinese Academy of SciencesBeijing 100190China Key Laboratory of Organic Optoelectronics and Molecular Engineering Department of ChemistryTsinghua UniversityBeijing 100084China Institute fo r Solid State Theory and Center for Multiscale Theory&Computation University of MuensterWilhelm-Klemm-Slrasse 10Muenster 48149Germany University of Chinese Academy of Sciences Beijing 100049China

Two diastereoisomers(NTPH-P and NTPH-T1) as a C2-symmetric triple [5]helicene based on N-annulated triperylene hexaimide were synthesized.Aided by nuclear magnetic resonance spectroscopy(NMR) and theoretical calculations,NTPH-P was assigned to three-blade propeller conformation while NTPH-T1 tended to exhibit twisted conformation with pyrrole ring fusing on a bowl-shaped PDI foil.Characterized by circular dichroism(CD) and circular polarized luminescence(CPL) measurements,the enantiomerically pure NTPH-P exhibited fairly good chiral activities both in the absorption and emission range with dissymmetry factors |gabs| of 4.1×10^-3 and |glum| of 1.2×10^-3.The diastereoisomers were further employed as acceptors for organic solar cells with distinct PCEs of 8.11% and 5.24% for NTPH-P and NTPH-T1 based devices,respectively,signifying the prospects in chiroptical electronics by designing molecularly defined aromatics.

关键词： triple helicenes perylene diimides N-annulation asymmetric decoration chiroptical properties organic solar cells

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

种植体与基台连接的微观形态学观察

引用

上海口腔医学 2018年第4期27卷 360-364页

作者：李晓娜 nikos Mattheos 大连市口腔医院特诊科辽宁大连116021 香港大学牙医学院口腔修复科香港999077

目的 :对种植体与原厂基台及第三方基台连接组件形态学上的微观特征进行观察,探讨形态差异与潜在并发症之间可能的关系。方法:3种基台(1个原厂装,2个来自第三方)在规定扭矩下装配到Straumann RN种植体上,种植体基台连接单元经过一系列... 详细信息

目的 :对种植体与原厂基台及第三方基台连接组件形态学上的微观特征进行观察,探讨形态差异与潜在并发症之间可能的关系。方法:3种基台(1个原厂装,2个来自第三方)在规定扭矩下装配到Straumann RN种植体上,种植体基台连接单元经过一系列包埋等程序后切割形成剖面,对剖面进行打磨,对完成的试件进行扫描电镜观察。采用图像测量软件(Image J)对获得的图片进行校准测量,比较三者之间在接触长度及接触性质之间的差异,尤其是3个重要部位即肩部、内连接及螺纹处的差异。结果:3个连接单元的所有被研究的接触面之间均存在一定的尺寸差异。3个单元中,种植体外肩部的紧密接触相似,但第三方基台内部连接的啮合,特别是抗旋转单元严重欠缺,其中1个第三方基台的螺丝啮合不良。结论:与原装基台对比,第三方基台呈现出关键性的形态差异,横断面的几何学差异导致总体接触面积有很大不同。无论从质量上,还是数量上这种差异对修复体的长期稳定性均有可能产生严重影响。

关键词：种植体基台连接微观形态学

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

甘肃临夏盆地中新世鬣狗科一新属新种

引用

古脊椎动物学报（中英文） 2022年第2期60卷 81-116页

作者： Henry GALIANO 曾志杰 nikos SOLOUNIAS 王晓鸣邱占祥 Stuart CWHITE 美国Maxilla and Mandible有限公司纽约10024 美国加州大学伯克利分校加州大学古生物博物馆伯克利94720 美国纽约自然历史博物馆纽约10024 美国洛杉矶自然历史博物馆洛杉矶90007 美国纽约理工大学医学院纽约11568 中国科学院古脊椎动物与古人类研究所北京100044 中国科学院大学北京100049 美国加州大学洛杉矶分校牙医学院洛杉矶90095

非洲土狼(Proteles cristatus)是鬣狗科中牙齿最为退化的一个种类,与其他化石及现生鬣狗物种粗壮的碎骨型牙齿形态截然不同。它的化石记录可以追溯到上新世,但尚缺少中间过渡形态的化石记录,以致生物学家对这一罕见的食蚁性食肉目动物... 详细信息

非洲土狼(Proteles cristatus)是鬣狗科中牙齿最为退化的一个种类,与其他化石及现生鬣狗物种粗壮的碎骨型牙齿形态截然不同。它的化石记录可以追溯到上新世,但尚缺少中间过渡形态的化石记录,以致生物学家对这一罕见的食蚁性食肉目动物的起源演化缺乏清楚的认知。描述了鬣狗科化石一新属甘肃鬣狗(Gansuyaena),并讨论其对于土狼起源的重要指示。所记述的标本为从海外收回的甘肃临夏盆地新近纪材料,包括两件破损头骨和下颌。基于甘肃鬣狗的形态特征,进行了一系列的系统发育分析,结果显示Proteles,Mesoviverrops,Plioviverrops和Gansuyaena组成一个相对原始的鬣狗类群,即土狼亚科(Protelinae)。而且,新的形态证据支持土狼亚科在形态粗壮的鬣狗亚科出现之前就已形成一个独立的支系。

关键词：甘肃临夏盆地中晚中新世鬣狗科土狼亚科

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Kemalism,Erdoganism and the Restructuring of Turkey

引用

土耳其研究 2018年第1期 122-141页

作者： nikos Christofis the Balkan Slavic and Oriental Studies Department at the University of Macedonia in ThessalonikiGreece the Hellenic Open University Greece

The article shows how the'New Turkey'(Yeni Türkiye), indeed a concept used widely since 2010 by the ruling Justice and Development Party(Adalet ve Kalkinma Partisi, AKP), is trying to (re) construct a new Turkish identity and (re) invent the Turkish nation. Despite the different perspectives on the issue, the article argues that this process during the AKP rule is taking place through the dominant paradigm for nearly a century, and in particular that of Kemalism. It is further argued that, all the elements during the Kemalist period are reappropriated in order to promote and reconstruct an imagined Turkish community anew and establish a new Turkish state tradition.

关键词： Kemalism state tradition AKP Erdogan(isation) nationalism

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Reasons of PEG failure to eliminate gastroesophageal reflux in mechanically ventilated patients

引用

World Journal of Gastroenterology 2009年第43期15卷 5455-5460页

作者： Emmanuel E Douzinas Ilias Andrianakis Olga Livaditi Dimitrios Bakos Katerina Flevari nikos Goutas Dimitrios Vlachodimitropoulos Marios-Konstantinos Tasoulis Alex P Betrosian 3rd Department of Critical Care Evgenidion HospitalUniversity of Athens Medical School Athens 115 28Greece The Laboratory of Pathology Evgenidion HospitalUniversity of Athens Medical SchoolAthens 115 28Greece

AIM:To investigate factors predicting failure of percutaneous endoscopic gastrostomy(PEG)to eliminate gastroesophageal reflux(GER). METHODS:Twenty-nine consecutive mechanically ventilated patients were investigated.Patients were evaluated for GER by pH-metry pre-PEG and on the 7th post-PEG day.Endoscopic and histologic evidence of reflux esophagitis was also carried out.A beneficial response to PEG was considered when pH-metry on the 7th post-PEG day showed that GER was below 4%. RESULTS:Seventeen patients responded(RESP group)and 12 did not respond(N-RESP)to PEG.The mean age,sex,weight and APACHEⅡscore were similar in both groups.GER(%)values were similar in both groups at baseline,but were significantly reduced in the RESP group compared with the N-RESP group on the 7th post-PEG day[2.5(0.6-3.8)vs 8.1(7.4-9.2, P<0.001)].Reflux esophagitis and the gastroesophageal flap valve(GEFV)grading differed significantly between the two groups(P=0.031 and P=0.020, respectively).Histology revealed no significant differences between the two groups.CONCLUSION:Endoscopic grading of GEFV and the presence of severe reflux esophagitis are predisposing factors for failure of PEG to reduce GER in mechanically ventilated patients.

关键词：聚乙二醇机械通气食管反流患者胃储蓄计划原因

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：