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Channelmeasurements and models for 6G: current status and future outlook
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作者 Jian-hua ZHANG† Pan TANG +2 位作者 Li YU Tao JIANG Lei TIAN 《信息与电子工程前沿:英文版》 SCIE EI CSCD 2020年第1期39-61,共23页
With the commercialization of fifth generation networks worldwide,research into sixth generation(6G)networks has been launched to meet the demands for high data rates and low latency for future services.A wireless pro... With the commercialization of fifth generation networks worldwide,research into sixth generation(6G)networks has been launched to meet the demands for high data rates and low latency for future services.A wireless propagation channel is the transmission medium to transfer information between the transmitter and the receiver.Moreover,channel properties determine the ultimate performance limit of wireless communication systems.Thus,conducting channel research is a prerequisite to designing 6G wireless communication systems.In this paper,we first introduce several emerging technologies and applications for 6G,such as terahertz communication,industrial Internet of Things,space-air-ground integrated network,and machine learning,and point out the developing trends of 6G channel models.Then,we give a review of channel measurements and models for the technologies and applications.Finally,the outlook for 6G channel measurements and models is discussed. 展开更多
关键词 Channel measurements Channel models Sixth generation TERAHERTZ Industrial Internet of Things Space-air-ground integrated network Machine learning
Breakdown voltage enhancement in GaN channel and AlGaN channel HEMTs using large gate metal height
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作者 王中旭 杜林 +11 位作者 刘俊伟 王颖 江芸 季思蔚 董士伟 陈伟伟 谭骁洪 李金龙 李小军 赵胜雷 张进成 郝跃 《中国物理B:英文版》 SCIE EI CAS CSCD 2020年第2期420-424,共5页
A large gate metal height technique is proposed to enhance breakdown voltage in GaN channel and AlGaN channel high-electron-mobility-transistors(HEMTs).For GaN channel HEMTs with gate-drain spacing LGD=2.5μm,the brea... A large gate metal height technique is proposed to enhance breakdown voltage in GaN channel and AlGaN channel high-electron-mobility-transistors(HEMTs).For GaN channel HEMTs with gate-drain spacing LGD=2.5μm,the breakdown voltage VBR increases from 518 V to 582 V by increasing gate metal height h from 0.2μm to 0.4μm.For GaN channel HEMTs with LGD=7μm,VBR increases from 953 V to 1310 V by increasing h from 0.8μm to 1.6μm.The breakdown voltage enhancement results from the increase of the gate sidewall capacitance and depletion region extension.For Al0.4Ga0.6N channel HEMT with LGD=7μm,VBR increases from 1535 V to 1763 V by increasing h from 0.8μm to 1.6μm,resulting in a high average breakdown electric field of 2.51 MV/cm.Simulation and analysis indicate that the high gate metal height is an effective method to enhance breakdown voltage in GaN-based HEMTs,and this method can be utilized in all the lateral semiconductor devices. 展开更多
关键词 GaN channel HEMTs AlGaN channel HEMTs breakdown voltage gate metal height
Marine Mobile Wireless Channel Modeling Based on Improved Spatial Partitioning Ray Tracing 预览
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作者 Zhibin Gao Bang Liu +2 位作者 Zhipeng Cheng Canbin Chen Lianfen Huang 《中国通信:英文版》 SCIE CSCD 2020年第3期1-11,共11页
In 5G era,it is expected to achieve wireless network coverage including offshore areas.Modeling of marine wireless channels is the basis of constructing a marine communication system.In this paper,a communication scen... In 5G era,it is expected to achieve wireless network coverage including offshore areas.Modeling of marine wireless channels is the basis of constructing a marine communication system.In this paper,a communication scene between an unmanned aerial vehicle(UAV)and a boat is simulated to study the marine wireless channel.Firstly,an improved spatial partitioning ray tracing algorithm is proposed to track the propagation path of electromagnetic waves at sea surface.Secondly,a mobile channel is simulated and modeled based on the track results.Finally,a loss measurement is carried out in the coastal waters based on the simple wireless channel loss measuring platform,and a path loss propagation model is built.Then we compare the actual measurement data with the simulation results and find that the two are have good consistency,which further verifies the reliability of the simulation. 展开更多
关键词 marine wireless channel ray tracing channel modeling path loss
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一次机五段后冷却器高压管箱隔膜密封结构设计 预览
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作者 陈孙艺 李志海 钟经山 《石油化工设备技术》 CAS 2020年第1期54-60,I0005,I0006共9页
为了精确设计某后冷器管箱端口球面隔膜密封结构,分别根据弹性力学理论和JB 4732-1995标准的有关解析式,对内压作用下高压管箱圆筒短节的径向位移进行了计算分析,并采用有限元模型分析进行比较验证,之后再结合操作工况主要参数的影响确... 为了精确设计某后冷器管箱端口球面隔膜密封结构,分别根据弹性力学理论和JB 4732-1995标准的有关解析式,对内压作用下高压管箱圆筒短节的径向位移进行了计算分析,并采用有限元模型分析进行比较验证,之后再结合操作工况主要参数的影响确定了隔膜的优化结构。经工程实践验证,结果表明:根据标准中的薄膜解析式计算的径向位移应用于本案例已具有足够的工程精度;球面隔膜比平面隔膜具有更大的径向弹性补偿作用,能改善密封紧固件的受力状况;管箱短节上组焊的内、外附件有加强作用,但是会引起端口径向位移沿周向分布的显著不均匀性,不利于密封。 展开更多
关键词 隔膜密封 密封设计 应力分析 脉动载荷 管箱
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Finite-State Markov Wireless Channel Modeling for Railway Tunnel Environments 预览
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作者 Cuiran Li Ling Liu Jianli Xie 《中国通信:英文版》 SCIE CSCD 2020年第2期30-39,共10页
In recent years,high-speed railways(HSRs)have developed rapidly with a high transportation capacity and high comfort level.A tunnel is a complex high-speed rail terrain environment.It is very important to establish an... In recent years,high-speed railways(HSRs)have developed rapidly with a high transportation capacity and high comfort level.A tunnel is a complex high-speed rail terrain environment.It is very important to establish an accurate channel propagation model for a railway tunnel environment to improve the safety of HSR operation.In this paper,a method for finite-state Markov chain(FSMC)channel modeling with least squares fitting based on non-uniform interval division is proposed.First,a path loss model is obtained according to measured data.The communication distance between the transmitter and receiver in the tunnel is non-uniformly divided into several large non-overlapping intervals based on the path loss model.Then,the Lloyd-Max quantization method is used to determine the threshold of the signal-to-noise ratio(SNR)and the channel state quantization value and obtain the FSMC state transition probability matrix.Simulation experiments show that the proposed wireless channel model has a low mean square error(MSE)and can accurately predict the received signal power in a railway tunnel environment. 展开更多
关键词 railway tunnel FSMC channel model SNR path loss
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深水重力流沉积类型与储集性能研究--以鄂尔多斯盆地西缘奥陶系拉什仲组为例 预览
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作者 王鹏伟 李华 +1 位作者 陈诚 刘映君 《海洋地质前沿》 CSCD 2020年第1期59-66,共8页
深水重力流的沉积类型及储集性能一直是沉积学领域研究的重点。此次研究以野外露头为基础,结合室内薄片分析,对鄂尔多斯盆地西缘奥陶系拉什仲组深水重力流沉积类型与储集性能进行了详细研究。拉什仲组以灰绿色砂岩及灰黑色泥岩为主,另... 深水重力流的沉积类型及储集性能一直是沉积学领域研究的重点。此次研究以野外露头为基础,结合室内薄片分析,对鄂尔多斯盆地西缘奥陶系拉什仲组深水重力流沉积类型与储集性能进行了详细研究。拉什仲组以灰绿色砂岩及灰黑色泥岩为主,另见少量的粉砂岩和砾岩。槽模、交错层理、粒序层理及包卷层理等发育。通过岩性、沉积构造、古生物等分析,认为拉什仲组沉积环境为深水,沉积相主要为海底扇,水道和朵叶微相较为发育。水道可进一步分为复合型、垂向加积型、迁移型。复合型水道岩性以砂岩为主,粒度较粗,水道内部发育次级水道。垂向加积型水道岩性为细砂岩和粉砂岩,以垂向加积沉积为主。迁移型水道定向迁移特征明显,侧积体发育。从下至上,砂岩含量先减少,再增加,大致反映相对海平面升-降旋回,海底扇总体呈退积沉积序列。孔隙度及渗透率测试结果表明,复合型水道储集潜力最好,朵叶和迁移型水道次之。 展开更多
关键词 水道 重力流 海底扇 拉什仲组 奥陶系 鄂尔多斯盆地
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火电厂励磁系统故障实例分析与探讨 预览
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作者 孙晋志 《电工技术》 2020年第6期106-107,共2页
文章介绍并分析了励磁调节器备用通道板卡故障和发电机出口PT慢熔两种情况下励磁系统未正确动作继而引发停机故障的过程、原因及后续处理防范措施。
关键词 励磁 故障 通道 逻辑 慢熔
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综放工作面回采顺槽掘进支护技术优化分析 预览
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作者 韩海洋 《山东煤炭科技》 2020年第3期15-17,共3页
以东周窑煤矿2102皮带顺槽巷道为工程背景,采用高预应力强力锚杆支护理论进行巷道支护优化,运用强锚杆、锚索联合支护技术,增加新开挖巷道围岩周围的承载力。结果表明,巷道支护优化起到了加强支护的作用,确保了2102顺槽在煌斑岩侵入下... 以东周窑煤矿2102皮带顺槽巷道为工程背景,采用高预应力强力锚杆支护理论进行巷道支护优化,运用强锚杆、锚索联合支护技术,增加新开挖巷道围岩周围的承载力。结果表明,巷道支护优化起到了加强支护的作用,确保了2102顺槽在煌斑岩侵入下掘进和工作面回采期间巷道的安全及稳定。 展开更多
关键词 综放 顺槽 支护 优化
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Endophilin A2 regulates calcium-activated chloride channel activity via selective autophagy-mediated TMEM16A degradation
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作者 Can-zhao Liu Fei-ya Li +5 位作者 Xiao-fei Lv Ming-ming Ma Xiang-yu Li Cai-xia Lin Guan-lei Wang Yong-yuan Guan 《中国药理学报:英文版》 SCIE CAS CSCD 2020年第2期208-217,共10页
TMEM16A Ca^2+-activated chloride channel(CaCC)plays an essential role in vascular homeostasis.In this study we investigated the molecular mechanisms underlying downregulation of TMEM16A CaCC activity during hypertensi... TMEM16A Ca^2+-activated chloride channel(CaCC)plays an essential role in vascular homeostasis.In this study we investigated the molecular mechanisms underlying downregulation of TMEM16A CaCC activity during hypertension.In cultured basilar artery smooth muscle cells(BASMCs)isolated from 2k2c renohypertesive rats,treatment with angiotensin II(0.125−1μM)dose-dependently increased endophilin A2 levels and decreased TMEM16A expression.Similar phenomenon was observed in basilar artery isolated from 2k2c rats.We then used whole-cell recording to examine whether endophilin A2 could regulate TMEM16A CaCC activity in BASMCs and found that knockdown of endophilin A2 significantly enhanced CaCC activity,whereas overexpression of endophilin A2 produced the opposite effect.Overexpression of endophilin A2 did not affect the TMEM16A mRNA level,but markedly decreased TMEM16A protein level in BASMCs by inducing ubiquitination and autophagy of TMEM16A.Ubiquitin-binding receptor p62(SQSTM1)could bind to ubiquitinated TMEM16A and resulted in a process of TMEM16A proteolysis in autophagosome/lysosome.These data provide new insights into the regulation of TMEM16A CaCC activity by endophilin A2 in BASMCs,which partly explains the mechanism of angiotensin-II-induced TMEM16A inhibition during hypertension-induced vascular remodeling. 展开更多
关键词 TMEM16A Ca^2+-activated chloride channel basilar smooth muscle cells angiotensin II endophilin A2 UBIQUITINATION AUTOPHAGY hypertension vascular remodeling
Hybrid Channel Access Mechanism Based on Coexistence Scenario of NR-Unlicensed 预览
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作者 Zhening Zhang Jingyi Chen +2 位作者 Mingyang Dong Yuehong Gao Jingjing Wang 《中国通信:英文版》 SCIE CSCD 2020年第1期49-62,共14页
With the rapid development of 5G NR(New Radio),the explosive increment of traffic amount is calling the utilization of unlicensed band.3GPP has proposed LAA(Licensed Assisted Access)to use LTE in unlicensed band and p... With the rapid development of 5G NR(New Radio),the explosive increment of traffic amount is calling the utilization of unlicensed band.3GPP has proposed LAA(Licensed Assisted Access)to use LTE in unlicensed band and pointed out that NR-U(NR-Unlicensed)can reuse most designs of it.However,the existing channel access mechanism of LAA is conservative under the coexistence scenario of NR-U,which leads to the waste of time resource.To address the problem this paper proposes a hybrid channel access mechanism to take advantage of the LBT(Listen-Before-Talk)mechanism of LAA when channel is quite busy and transmit directly with reduced power when it is relatively idle.The channel busy degree is judged by a series of periodically updated adaptive thresholds.System-level simulation verifies that under the coexistence scenario of NR-U the proposed mechanism can achieve higher UPT(User Perceived Throughput)and lower delay than other channel access mechanisms. 展开更多
关键词 NR-U channel access mechanism LBT power reduction
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SCN9A Epileptic Encephalopathy Mutations Display a Gain-offunction Phenotype and Distinct Sensitivity to Oxcarbazepine
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作者 Shuzhang Zhang Zhiping Zhang +5 位作者 Yuan Shen Yudan Zhu Kun Du Jingkang Guo Yonghua Ji Jie Tao 《神经科学通报:英文版》 SCIE CAS CSCD 2020年第1期11-24,共14页
Genetic mutants of voltage-gated sodium channels(VGSCs)are considered to be responsible for the increasing number of epilepsy syndromes.Previous research has indicated that mutations of one of the VGSC genes,SCN9A(Nav... Genetic mutants of voltage-gated sodium channels(VGSCs)are considered to be responsible for the increasing number of epilepsy syndromes.Previous research has indicated that mutations of one of the VGSC genes,SCN9A(Navl.7),result in febrile seizures and Dravet syndrome in humans.Despite these recent efforts,the electrophysiological basis of SCN9A mutations remains unclear.Here,we performed a genetic screen of patients with febrile seizures and identified a novel missense mutation of SCN9A(W1150R).Electrophysiological characterization of different SCN9A mutants in HEK293T cells,the previously-reported N641Y and K655R variants,as well as the newly-found W1150R variant,revealed that the current density of the W1150R and N641Y variants was significantly larger than that of the wild-type(WT)channel.The time constants of recovery from fast inactivation of the N641Y and K655R variants were markedly lower than in the WT channel.The W1150R variant caused a negative shift of the G-V curve in the voltage dependence of steady-state activation.All mutants displayed persistent currents larger than the WT channel.In addition,we found that oxcarbazepine(OXC),one of the antiepileptic drugs targeting VGSCs,caused a significant shift to more negative potential for the activation and inactivation in WT and mutant channels.OXC-induced inhibition of currents was weaker in the W1150R variant than in the WT.Furthermore,with administering OXC the time constant of the N641Y variant was longer than those of the other two SCN9A mutants.In all,our results indicated that the point mutation W1150R resulted in a novel gain-of-function variant.These findings indicated that SCN9A mutants contribute to an increase in seizure,and show distinct sensitivity to OXC. 展开更多
关键词 Voltage-gated sodium channel SCN9A EPILEPSY Electrophysiological function OXCARBAZEPINE Sensitivity Introduction
An enhanced searchable encryption scheme for secure data outsourcing
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作者 Rui ZHANG Jiabei WANG +1 位作者 Zishuai SONG Xi WANG 《中国科学:信息科学(英文版)》 SCIE EI CSCD 2020年第3期114-129,共16页
In the cloud environment, where the cloud server cannot always be fully trusted, both data and query privacy should be well protected for secure data outsourcing. Searchable encryption provides a more practical soluti... In the cloud environment, where the cloud server cannot always be fully trusted, both data and query privacy should be well protected for secure data outsourcing. Searchable encryption provides a more practical solution to secure data storage while enabling efficient search queries. In this paper, four important problems of public key encryption with keyword search(PEKS), namely, a scheme without secure channels,conjunctive keyword search,(offline) outside and inside keyword guessing attack(full KGA) resistance and proof in the standard model, are considered. We provide an in-depth analysis of the reasons behind(offline)full KGA by considering two types of PEKS schemes as examples. In particular, we introduce the concept of server-aided secure channel free public key encryption with conjunctive keyword search(SA-SCF-PECKS)which can resist(offline) full KGA. Furthermore, we provide a concrete and efficient construction of SA-SCFPECKS, and prove its security in the standard model. To the best of our knowledge, our proposal is the first PECKS scheme to address these four problems simultaneously. We compare the security and efficiency of our scheme with those of other related PECKS schemes in theoretical and practical ways. In general,compared with other schemes, our SA-SCF-PECKS scheme shows better performance in terms of security and efficiency. 展开更多
关键词 secure data outsourcing (offline)outside and inside keyword guessing attack secure channel free PEKS conjunctive keyword search server-aided scheme standard model
Distribution and Functional Characteristics of Voltage-Gated Sodium Channels in Immature Cochlear Hair Cells
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作者 You Zhou Chenchen Xia +3 位作者 Manli Yi Xueling Wang Hao Wu Yonghua Ji 《神经科学通报:英文版》 SCIE CAS CSCD 2020年第1期49-65,共17页
Voltage-gated sodium channels(VGSCs)are transiently expressed in cochlear hair cells before hearing onset and play an indispensable role in shaping spontaneous activity.In this study,we showed that Na^+currents shaped... Voltage-gated sodium channels(VGSCs)are transiently expressed in cochlear hair cells before hearing onset and play an indispensable role in shaping spontaneous activity.In this study,we showed that Na^+currents shaped the spontaneous action potentials in developing mouse inner hair cells(IHCs)by decreasing the time required for the membrane potential to reach the action-potential threshold.In immature IHCs,we identified 9 known VGSC subtypes(Navl.la-l.9ot),among which Navl.7a was the most highly expressed subtype and the main contributor to Na+currents in developing hair cells.Electrophysiological recordings of two cochlea-specific Navi.7 variants(CbmNavl.7a and CbmNavl.7b)revealed a novel loss-of-function mutation(C934R)at the extracellular linker between segments 5 and 6 of domain II.In addition,post-transcriptional modification events,such as alternative splicing and RNA editing,amended the gating properties and kinetic features of CbmNavl.7a(C934).These results provide molecular and functional characteristics of VGSCs in mammalian IHCs and their contributions to spontaneous physiological activity during cochlear maturation. 展开更多
关键词 Cochlear hair cell Spontaneous action potential Voltage-gated sodium channel Post-transcriptional modification Gating property Introduction
缅甸伊洛瓦底三角洲河道演变遥感研究 预览
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作者 陈丹 《江苏科技信息》 2020年第1期46-50,共5页
文章在遥感技术与地理信息系统的支持下,利用长时间序列遥感影像对缅甸伊洛瓦底三角洲主河道进行演变研究。采用有利于减少噪声的水体监测指数MNDWI计算方法以实现水陆分离,进而从河道长度、宽度、弯曲指数及辫状指数4个方面分析河道演... 文章在遥感技术与地理信息系统的支持下,利用长时间序列遥感影像对缅甸伊洛瓦底三角洲主河道进行演变研究。采用有利于减少噪声的水体监测指数MNDWI计算方法以实现水陆分离,进而从河道长度、宽度、弯曲指数及辫状指数4个方面分析河道演变规律。结果表明,河道长度、宽度、弯曲指数及辫状指数分别呈现不同程度的上升趋势。在此基础上,能够根据历史河道变化趋势预测河道未来演变位置,有利于及时进行风险防范,维护沿岸稳定。 展开更多
关键词 伊洛瓦底三角洲 河道 演变 遥感
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Electro-optomechanical cooperative cooling of nanomechanical oscillator beyond resolved sideband regime
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作者 ZhongHui Yuan DongYang Wang +3 位作者 ChengHua Bai HaoTian Yang HongFu Wang AiDong Zhu 《中国科学:物理学、力学、天文学英文版》 SCIE EI CAS CSCD 2020年第3期25-32,共8页
We propose a ground-state cooling scheme for a nanomechanical oscillator(NMO)that interacts with an optical cavity via radiation pressure at one side and with a superconducting microwave cavity via a capacitor at the ... We propose a ground-state cooling scheme for a nanomechanical oscillator(NMO)that interacts with an optical cavity via radiation pressure at one side and with a superconducting microwave cavity via a capacitor at the other side.By driving these two cavities on their respective red sidebands with extra laser and microwave fields,the NMO’s dual cooling channel is created through electro-optomechanical cooperation.Differing from the conventional optomechanical system with a single optical cavity wherein ground-state cooling is limited in the resolved sideband,the proposed scheme allows the optical cavity to function in an unresolved sideband regime under the cooperation of a microwave cavity with a high quality factor,or vice versa.In a weak coupling regime we demonstrate that the NMO can be cooled to near its ground-state from a finite temperature with a cooling rate that is significantly faster than that of the single-cavity optomechanical system.The heating process can be completely suppressed by the cooperation of the dual cooling channel by appropriately selecting the system’s parameters.With a decreasing thermal phonon number,the numerical results of final mechanical occupancy gradually approach the analytical cooling limit. 展开更多
关键词 electro-optomechanics superconducting microwave cavity ground-state cooling dual cooling channel
Unimolecular artificial transmembrane channel with terminal dihydrogen phosphate groups showing transport selectivity for ammonium
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作者 Jian-Yu Chen Qi Xiao +1 位作者 Harekrushna Behera Jun-Li Hou 《中国化学快报:英文版》 SCIE CAS CSCD 2020年第1期77-80,共4页
A new artificial transmembrane channel molecule bearing dihydrogen phosphate groups has been synthesized.The terminal dihydrogen phosphate groups enable the channel to be highly negatively charged at both ends of the ... A new artificial transmembrane channel molecule bearing dihydrogen phosphate groups has been synthesized.The terminal dihydrogen phosphate groups enable the channel to be highly negatively charged at both ends of the channel structures.The artificial channel could incorporate into the lipid bilayer efficiently under low concentration.The channel displays high NH4+/K+selectivity due to the electrostatic interaction and hydrogen bonding between NH4+and the terminal dihydrogen phosphate groups. 展开更多
关键词 Artificial transmembrane channel Ammonium transport Dihydrogen phosphate arene Transmembrane transport Transport selectivity
High-throughput fabrication and semi-automated characterization of oxide thin film transistors
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作者 韩炎兵 Sage Bauers +1 位作者 张群 Andriy Zakutayev 《中国物理B:英文版》 SCIE EI CAS CSCD 2020年第1期82-88,共7页
High throughput experimental methods are known to accelerate the rate of research,development,and deployment of electronic materials.For example,thin films with lateral gradients in composition,thickness,or other para... High throughput experimental methods are known to accelerate the rate of research,development,and deployment of electronic materials.For example,thin films with lateral gradients in composition,thickness,or other parameters have been used alongside spatially-resolved characterization to assess how various physical factors affect the material properties under varying measurement conditions.Similarly,multi-layer electronic devices that contain such graded thin films as one or more of their layers can also be characterized spatially in order to optimize the performance.In this work,we apply these high throughput experimental methods to thin film transistors(TFTs),demonstrating combinatorial channel layer growth,device fabrication,and semi-automated characterization using sputtered oxide TFTs as a case study.We show that both extrinsic and intrinsic types of device gradients can be generated in a TFT library,such as channel thickness and length,channel cation compositions,and oxygen atmosphere during deposition.We also present a semi-automated method to measure the 44 devices fabricated on a 50 mm×50 mm substrate that can help to identify properly functioning TFTs in the library and finish the measurement in a short time.Finally,we propose a fully automated characterization system for similar TFT libraries,which can be coupled with high throughput data analysis.These results demonstrate that high throughput methods can accelerate the investigation of TFTs and other electronic devices. 展开更多
关键词 combinatorial sputtering indium zinc oxide(IZO)thin film transistor(TFT) channel gradient oxygen content
Geolocator study reveals east African migration route of Central European Common Terns 预览
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作者 Jelena Kralj Milos Martinovic +3 位作者 Luka Jurinovic Peter Szinai Szandra Suto Balint Preiszner 《鸟类学研究:英文版》 CSCD 2020年第1期34-44,共11页
Background: The majority of European Common Terns(Sterna hirundo) migrate south along the western coast of Europe and Africa, while birds from eastern regions are known to cross the Mediterranean Sea from east to west... Background: The majority of European Common Terns(Sterna hirundo) migrate south along the western coast of Europe and Africa, while birds from eastern regions are known to cross the Mediterranean Sea from east to west or migrate along the eastern African coast. The migration route of north European terns wintering along the coast of western Africa was already described using geolocator data, while knowledge about movements of the European inland populations is based only on relatively scarce recoveries of ringed birds.Methods: We used light-level geolocators in inland Common Tern colonies in Hungary and Croatia to study their migration route and to identify wintering areas along with stopover sites. Results revealed by geolocators were compared with recoveries of ringed birds.Results: All tracked birds used the east African migration route with autumn stopovers at Lower Nile and in the southern part of the Red Sea, and short spring stopover in Israel. Terns wintered along Kenyan coasts and in the southern Mozambique Channel. Autumn migration lasted four times longer than spring migration.Conclusions: This is the first geolocator study that describes the east African migration route of the Common Tern. Important stopover sites were identified. More studies of inland populations are needed to better elucidate tern winter movements. 展开更多
关键词 Inland population Light-level geolocators Mozambique Channel Red Sea Sterna hirundo Stopover sites Wintering area
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明代黄河银川平原段河道位置新探 预览
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作者 翟飞 《人民黄河》 CAS 北大核心 2020年第3期34-39,72,共7页
明代黄河银川平原段河道迁徙、摆荡频繁,历代罕有。结合文献记载,辅之考古调查及自然地理等相关资料,对黄河银川平原段南、北两段展开逐步探索。总体上从明代灵州城的三次迁建、银川平原黄河沿岸明代及以前古代遗迹的分布及河中堡、高... 明代黄河银川平原段河道迁徙、摆荡频繁,历代罕有。结合文献记载,辅之考古调查及自然地理等相关资料,对黄河银川平原段南、北两段展开逐步探索。总体上从明代灵州城的三次迁建、银川平原黄河沿岸明代及以前古代遗迹的分布及河中堡、高台寺、省嵬城的空间位置等进行探索,从而对明代黄河银川平原段河道位置作出简单勾勒。 展开更多
关键词 明代 黄河 灵州城 银川平原 河道
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Effects of Tidal Channels and Roads on Landscape Dynamic Distribution in the Yellow River Delta,China 预览
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作者 YU Xiaojuan ZHANG Zhongsheng +2 位作者 XUE Zhenshan WU Haitao ZHANG Hongri 《中国地理科学:英文版》 SCIE CSCD 2020年第1期170-179,共10页
Landscape characters in estuarine regions generally controlled by tidal regimes and human activities like road construction.In this work,tidal channels and road construction in the Yellow River Delta(YRD)were extracte... Landscape characters in estuarine regions generally controlled by tidal regimes and human activities like road construction.In this work,tidal channels and road construction in the Yellow River Delta(YRD)were extracted by visual interpretation methods so as to decipher impacts of tidal channel development and road construction on landscape patch change during 1989–2016.Spatial distribution history of three wetlands,which covered by Phragmites australis(freshwater marsh,FM),Suaeda salsa(salt marsh,SM),and mudflats(MD)were also established.Results indicated that tidal channel,number,frequency,and fractal dimension were all the maximum in 2003,and the minimum in 1998,respectively.Road length,number,and density showed increasing trend during 1989–2016.MD were the predominant landscape type,followed by FM and SM during 1989-2016.Principal component analysis implied two extracted factors,F1 and F2,which could represent 91.93% of the total variations.F1 mainly proxied tidal channel development,while F2 represented road construction.A multiple linear regression analysis showed positive effects of both F1 and F2 on FM patch numbers and negative impacts on SM patch areaes with R^2 values of 0.416 and 0.599,respectively.Tidal channels were negatively related to MD patch numbers,while roads were positively related to that.In any case,road construction showed larger impacts on landscape type shifting than that of tidal channel development in the YRD. 展开更多
关键词 tidal channel development road construction principal component analysis multiple linear regression analysis the Yellow River Delta
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