| 1. |
- Canton, S. E., et al.
(author)
-
Watching the dynamics of electrons and atoms at work in solar energy conversion
- 2015
-
In: Faraday discussions. - : Royal Society of Chemistry. - 1359-6640 .- 1364-5498. ; 185, s. 51-68
-
Journal article (peer-reviewed)abstract
- The photochemical reactions performed by transition metal complexes have been proposed as viable routes towards solar energy conversion and storage into other forms that can be conveniently used in our everyday applications. In order to develop efficient materials, it is necessary to identify, characterize and optimize the elementary steps of the entire process on the atomic scale. To this end, we have studied the photoinduced electronic and structural dynamics in two heterobimetallic ruthenium-cobalt dyads, which belong to the large family of donor-bridge-acceptor systems. Using a combination of ultrafast optical and X-ray absorption spectroscopies, we can clock the light-driven electron transfer processes with element and spin sensitivity. In addition, the changes in local structure around the two metal centers are monitored. These experiments show that the nature of the connecting bridge is decisive for controlling the forward and the backward electron transfer rates, a result supported by quantum chemistry calculations. More generally, this work illustrates how ultrafast optical and X-ray
|
|
| 2. |
- Molisch, Andreas, et al.
(author)
-
DFT-based Hybrid Antenna Selection Schemes for spatially correlated MIMO channels
- 2003
-
In: 14th IEEE Proceedings on Personal, Indoor and Mobile Radio Communications, PIMRC 2003.. - 0780378229 ; 2, s. 1119-1123
-
Conference paper (peer-reviewed)abstract
- We address the antenna subset selection problem in spatially correlated MIMO channels. To reduce the severe performance degradation of the traditional antenna selection scheme in correlated channels, we propose to embed DFT operations in the RF chains. The resulting system shows a significant advantage both for diversity schemes and for the capacity of spatial multiplexing, while requiring only a minor hardware overhead.
|
|
| 3. |
- Molisch, Andreas, et al.
(author)
-
FFT-based hybrid antenna selection schemes for spatially correlated MIMO channels
- 2004
-
In: IEEE Communications Letters. - 1089-7798. ; 8:1, s. 36-38
-
Journal article (peer-reviewed)abstract
- In this letter, we address the antenna subset selection problem in spatially correlated multiple-input multiple-output (MIMO) channels. To reduce the severe performance degradation of the traditional antenna selection scheme in correlated channels, we propose to embed fast Fourier transform operations in the RF chains. The resulting system shows a significant advantage both for diversity schemes and for the capacity of spatial multiplexing, while requiring only a minor hardware overhead.
|
|
| 4. |
- Zhang, X, et al.
(author)
-
Phase-shift-based antenna selection for MIMO channels
- 2003
-
In: IEEE Global Telecommunications Conference, 2003. GLOBECOM '03.. - 0780379748 ; 2, s. 1089-1093
-
Conference paper (peer-reviewed)abstract
- This paper addresses the antenna subset selection in multiple antenna systems with full diversity transmission, for both correlated and uncorrelated channels. To reduce the severe performance degradation of traditional selection/combining schemes, we propose to embed phase-shift-only operations in the RF chains before selection. The resulting system shows a significant advantage in utilizing the multiple antenna diversity under almost any channel condition while incurring only a small hardware overhead. With the optimum phase shifter design given in analytical form, our analysis shows that with more than two branches allowed for selection, the new scheme can achieve the same SNR gain as the full-complexity MRC (maximum-ratio-combining). Even when only one branch is allowed, the performance is still well above the conventional selection scheme and near optimum.
|
|
| 5. |
- Jacobsson, Jesper, 1984-, et al.
(author)
-
An open-access database and analysis tool for perovskite solar cells based on the FAIR data principles
- 2022
-
In: Nature Energy. - : Springer Nature. - 2058-7546. ; 7:1, s. 107-115
-
Journal article (peer-reviewed)abstract
- Large datasets are now ubiquitous as technology enables higher-throughput experiments, but rarely can a research field truly benefit from the research data generated due to inconsistent formatting, undocumented storage or improper dissemination. Here we extract all the meaningful device data from peer-reviewed papers on metal-halide perovskite solar cells published so far and make them available in a database. We collect data from over 42,400 photovoltaic devices with up to 100 parameters per device. We then develop open-source and accessible procedures to analyse the data, providing examples of insights that can be gleaned from the analysis of a large dataset. The database, graphics and analysis tools are made available to the community and will continue to evolve as an open-source initiative. This approach of extensively capturing the progress of an entire field, including sorting, interactive exploration and graphical representation of the data, will be applicable to many fields in materials science, engineering and biosciences.
|
|
| 6. |
- Landin, L., et al.
(author)
-
Interband transitions in InAs quantum dots in InP studied by photoconductivity and photoluminescence techniques
- 2004
-
In: Journal of Applied Physics. - Melville : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 95:12, s. 8007-8010
-
Journal article (peer-reviewed)abstract
- We report on a detailed investigation of the interband optics of self-assembled InAs dots embedded in a matrix of InP. In photoconductivity (PC) measurements, we observe optical processes related to the dots and a wetting layer, band-to-band excitation of the InP barrier, as well as to an interesting As-related impurity. In particular, the PC measurements reveal the electronic structure of the dots and strongly suggest that an Auger effect is involved in forming the PC signal. Comparing the PC and photoluminescence (PL) signals, we observe that the fundamental transition is not observed in PC, which we interpret in terms of Pauli blocking due to electrons populating the ground state of the dots. In general, it is demonstrated that the PC technique is in many respects complementary to PL and gives additional insight into the electronic structure of quantum dots.
|
|
| 7. |
- Yasuda, H, et al.
(author)
-
Prediction of Chinese Loess Plateau summer rainfall using Pacific Ocean spring sea surface temperature
- 2009
-
In: Hydrological Processes. - : Wiley. - 1099-1085 .- 0885-6087. ; 23:5, s. 719-729
-
Journal article (peer-reviewed)abstract
- The Loess Plateau in China constitutes in important source area for both water and sediments to the Yellow River. Thus, improved prediction techniques of rainfall may lead to better estimation of discharge and sediment content for the Yellow River. Consequently. the objective of this study was to establish better links between rainfall of the Loess Plateau in China and sea surface temperature (SST) in the Pacific Ocean. Results showed that there is a strong lagged correlation between and SST and rainfall. The SST for Micronesia and areas South of the Aleutian Islands showed significant correlations (s.f. < 0.001: 99.9%) with rainfall over the dryer region of the Loess Plateau for a lag of 4 to 6 months. The SST over the equator On the cast Pacific Ocean also showed significant negative correlation with rainfall. Low and middle latitude areas (S10-20 degrees and around 30 degrees) of the south-east Pacific Ocean displayed significant positive and negative correlation with rainfall on the semiarid Loess Plateau. The differenced SST values (positive SST minus negative SST) increased these correlation,, with rainfall. An artificial neural network (ANN) model was used to predict Summer rainfall from the differenced SST during, the spring period. The correlation between predicted and observed months), rainfall was in general larger than 0.7. This indicates that major annual rainfall (during summer season) can be predicted with good accuracy using the suggested approach. Copyright (D 2008 John Wiley & Sons. Ltd.
|
|
