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Potential for Early Forecast of Moroccan Wheat Yields Based on Climatic Drivers 期刊论文
GEOPHYSICAL RESEARCH LETTERS, 2020, 47 (12)
作者:  Lehmann, J.;  Kretschmer, M.;  Schauberger, B.;  Wechsung, F.
收藏  |  浏览/下载:18/0  |  提交时间:2020/05/20
causal discovery algorithms  teleconnections  seasonal forecast  machine learning  wheat forecast  climate precursors  
Multi-model ensemble predictions of precipitation and temperature using machine learning algorithms 期刊论文
ATMOSPHERIC RESEARCH, 2020, 236
作者:  Ahmed, Kamal;  Sachindra, D. A.;  Shahid, Shamsuddin;  Iqbal, Zafar;  Nawaz, Nadeem;  Khan, Najeebullah
收藏  |  浏览/下载:16/0  |  提交时间:2020/07/02
General circulation models  Multi-model ensemble  Taylor skill score  Machine learning algorithms  Temperature and precipitation  Pakistan  
Do Existing Multiobjective Evolutionary Algorithms Use a Sufficient Number of Operators? An Empirical Investigation for Water Distribution Design Problems 期刊论文
WATER RESOURCES RESEARCH, 2020, 56 (5)
作者:  Wang, Peng;  Zecchin, Aaron C.;  Maier, Holger R.;  Zheng, Feifei;  Newman, Jeffrey P.
收藏  |  浏览/下载:13/0  |  提交时间:2020/07/02
multiobjective evolutionary algorithms  operators  water distribution system design optimization  Borg  GALAXY  NSGA-II  
Operation of a silicon quantum processor unit cell above one kelvin 期刊论文
NATURE, 2020, 580 (7803) : 350-+
作者:  Han, Kyuho;  Pierce, Sarah E.;  Li, Amy;  Spees, Kaitlyn;  Anderson, Grace R.;  Seoane, Jose A.;  Lo, Yuan-Hung;  Dubreuil, Michael;  Olivas, Micah;  Kamber, Roarke A.;  Wainberg, Michael;  Kostyrko, Kaja;  Kelly, Marcus R.;  Yousefi, Maryam;  Simpkins, Scott W.;  Yao, David
收藏  |  浏览/下载:8/0  |  提交时间:2020/07/03

Quantum computers are expected to outperform conventional computers in several important applications, from molecular simulation to search algorithms, once they can be scaled up to large numbers-typically millions-of quantum bits (qubits)(1-3). For most solid-state qubit technologies-for example, those using superconducting circuits or semiconductor spins-scaling poses a considerable challenge because every additional qubit increases the heat generated, whereas the cooling power of dilution refrigerators is severely limited at their operating temperature (less than 100 millikelvin)(4-6). Here we demonstrate the operation of a scalable silicon quantum processor unit cell comprising two qubits confined to quantum dots at about 1.5 kelvin. We achieve this by isolating the quantum dots from the electron reservoir, and then initializing and reading the qubits solely via tunnelling of electrons between the two quantum dots(7-9). We coherently control the qubits using electrically driven spin resonance(10,11) in isotopically enriched silicon(12 28)Si, attaining single-qubit gate fidelities of 98.6 per cent and a coherence time of 2 microseconds during '  hot'  operation, comparable to those of spin qubits in natural silicon at millikelvin temperatures(13-16). Furthermore, we show that the unit cell can be operated at magnetic fields as low as 0.1 tesla, corresponding to a qubit control frequency of 3.5 gigahertz, where the qubit energy is well below the thermal energy. The unit cell constitutes the core building block of a full-scale silicon quantum computer and satisfies layout constraints required by error-correction architectures(8),(17). Our work indicates that a spin-based quantum computer could be operated at increased temperatures in a simple pumped He-4 system (which provides cooling power orders of magnitude higher than that of dilution refrigerators), thus potentially enabling the integration of classical control electronics with the qubit array(18,19).


  
Spatial mapping of the provenance of storm dust: Application of data mining and ensemble modelling 期刊论文
ATMOSPHERIC RESEARCH, 2020, 233
作者:  Gholami, Hamid;  Mohamadifar, Aliakbar;  Collins, Adrian L.
收藏  |  浏览/下载:5/0  |  提交时间:2020/07/02
Dust provenance  Spatial modelling  Data mining algorithms  Multicollinearity  Receiver operating characteristic  Ensemble modelling  R software  
Coherent electrical control of a single high-spin nucleus in silicon 期刊论文
NATURE, 2020, 579 (7798) : 205-+
作者:  Dedoussi, Irene C.;  Eastham, Sebastian D.;  Monier, Erwan;  Barrett, Steven R. H.
收藏  |  浏览/下载:10/0  |  提交时间:2020/07/03

Nuclear spins are highly coherent quantum objects. In large ensembles, their control and detection via magnetic resonance is widely exploited, for example, in chemistry, medicine, materials science and mining. Nuclear spins also featured in early proposals for solid-state quantum computers(1) and demonstrations of quantum search(2) and factoring(3) algorithms. Scaling up such concepts requires controlling individual nuclei, which can be detected when coupled to an electron(4-6). However, the need to address the nuclei via oscillating magnetic fields complicates their integration in multi-spin nanoscale devices, because the field cannot be localized or screened. Control via electric fields would resolve this problem, but previous methods(7-9) relied on transducing electric signals into magnetic fields via the electron-nuclear hyperfine interaction, which severely affects nuclear coherence. Here we demonstrate the coherent quantum control of a single Sb-123 (spin-7/2) nucleus using localized electric fields produced within a silicon nanoelectronic device. The method exploits an idea proposed in 1961(10) but not previously realized experimentally with a single nucleus. Our results are quantitatively supported by a microscopic theoretical model that reveals how the purely electrical modulation of the nuclear electric quadrupole interaction results in coherent nuclear spin transitions that are uniquely addressable owing to lattice strain. The spin dephasing time, 0.1 seconds, is orders of magnitude longer than those obtained by methods that require a coupled electron spin to achieve electrical driving. These results show that high-spin quadrupolar nuclei could be deployed as chaotic models, strain sensors and hybrid spin-mechanical quantum systems using all-electrical controls. Integrating electrically controllable nuclei with quantum dots(11,12) could pave the way to scalable, nuclear- and electron-spin-based quantum computers in silicon that operate without the need for oscillating magnetic fields.


  
The Australian Northwest Cloudband: Climatology, Mechanisms, and Association with Precipitation 期刊论文
JOURNAL OF CLIMATE, 2019, 32 (20) : 6665-6684
作者:  Reid, Kimberley J.;  Simmonds, Ian;  Vincent, Claire L.;  King, Andrew D.
收藏  |  浏览/下载:6/0  |  提交时间:2019/11/27
Australia  Synoptic climatology  Precipitation  Algorithms  Satellite observations  
A High-Resolution 1983-2016 T-max Climate Data Record Based on Infrared Temperatures and Stations by the Climate Hazard Center 期刊论文
JOURNAL OF CLIMATE, 2019, 32 (17) : 5639-5658
作者:  Funk, Chris;  Peterson, Pete;  Peterson, Seth;  Shukla, Shraddhanand;  Davenport, Frank;  Michaelsen, Joel;  Knapp, Kenneth R.;  Landsfeld, Martin;  Husak, Gregory;  Harrison, Laura;  Rowland, James;  Budde, Michael;  Meiburg, Alex;  Dinku, Tufa;  Pedreros, Diego;  Mata, Nicholas
收藏  |  浏览/下载:11/0  |  提交时间:2019/11/27
Climatology  Temperature  Algorithms  Climate records  Remote sensing  Satellite observations  
Surface Meteorological Conditions and Boundary Layer Height Variations During an Air Pollution Episode in Nanjing, China 期刊论文
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 2019, 124 (6) : 3350-3364
作者:  Yin, J.;  Gao, C. Y.;  Hong, J.;  Gao, Z.;  Li, Y.;  Li, X.;  Fan, S.;  Zhu, B.
收藏  |  浏览/下载:8/0  |  提交时间:2019/11/26
planetary boundary layer height  ceilometer  retrieval algorithms  air pollution  Nanjing  
Comparison of machine learning algorithms for forest parameter estimations and application for forest quality assessments 期刊论文
FOREST ECOLOGY AND MANAGEMENT, 2019, 434: 224-234
作者:  Zhao, Qingxia;  Yu, Shichuan;  Zhao, Fei;  Tian, Linghong;  Zhao, Zhong
收藏  |  浏览/下载:4/0  |  提交时间:2019/04/09
Machine learning algorithms (MLAs)  Forest parameter estimations  Forest quality (FQ)  Black locust (Robinia pseudoacacia)