| 1. |
|
|
| 2. |
- Monteiro, Margarida, et al.
(författare)
-
X-ray Photoelectron Spectroscopy for Studying Passivation Architectures of Cu(In,Ga)Se-2 Cells
- 2021
-
Ingår i: 2021 IEEE 48th Photovoltaic Specialists Conference (PVSC). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781665419222 ; , s. 890-892
-
Konferensbidrag (refereegranskat)abstract
- Optoelectronic devices are susceptible to interface recombination, which can have a detrimental impact on their performance. Therefore, there is an urgent need for tailored passivation strategies to reach a technological boost. In this contribution, two architectures based on passivated Cu(In, Ga)Se-2 solar cells are analyzed with X-ray photoelectron spectroscopy (XPS): one based on rear passivation with gold nanoparticle aggregates, and the other with Al2O3 as a front passivation layer. It is demonstrated that XPS can assist in the understanding of passivated devices from a chemical point of view, comprehend their limitations and push forward the development of future devices.
|
|
| 3. |
- Oliveira, Kevin, et al.
(författare)
-
SiOx patterned based substrates implemented in Cu(In,Ga)Se-2 ultrathin solar cells : optimum thickness
- 2021
-
Ingår i: 2021 IEEE 48th Photovoltaic Specialists Conference (PVSC). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781665419222 ; , s. 928-930
-
Konferensbidrag (refereegranskat)abstract
- Interface recombination in sub-mu m optoelectronic devices has a major harmful impact in devices performance, showing the need for tailored passivation strategies in order to reach a technological boost. In this work, SiOx based substrates were developed and integrated in ultrathin CIGS solar cells. This study aims at understanding the impact of several SiOx layer thicknesses (3, 8 and 25 nm) when this material is used as a passivation layer. Analysing their electrical parameters, the 8 nm novel SiOx based substrates achieved light to power conversion efficiency values up to 13.2 %, a 1.3 % absolute improvement over the conventional substrate (without SiOx).
|
|
| 4. |
|
|
| 5. |
- da Silva, Paulo S P, et al.
(författare)
-
Release of carbon and nitrogen during pylolysis of reduced lignin black liquors : experimental results
- 2017
-
Ingår i: International chemical recovery conference, May 24-26, 2017, Halifax, Canada.
-
Konferensbidrag (refereegranskat)abstract
- Removing lignin from black liquor is of increasing industrial interest. It has the potential to create a new product stream for pulp mills as well as being a method for reducing the load of over-loaded recovery boilers. Currently, there is very little information on the combustion properties of reduced lignin black liquors. Of particular importance is the split of carbon and nitrogen. The carbon split is especially important because it plays an important role in how much carbon reaches the char bed. This in turn affects the lower furnace temperature, which plays an important role in reduction efficiency; sulfur and alkali release; and NO and cyanate formation. The nitrogen split is of interest because a part of the black liquor nitrogen precipitates with the lignin, potentially changing the behavior of black liquor N. The purpose of this work is to investigate the effect of lignin removal on carbon and nitrogen distribution between volatiles and char during pyrolysis. In this work, black liquors (one SW and one eucalyptus) with different levels of lignin removal were pyrolysed in a single particle furnace for 2 seconds at temperatures from 900°C to 1100°. Additional softwood and hardwood liquors were also pyrolyzed in order to study liquor to liquor variability. The carbon and nitrogen splits were obtained by analyzing the chars from the pyrolysis experiments using a CHNS elemental analyzer. Results show a similar carbon split for liquors with up to 25% lignin removal. The nitrogen split was also found to be fairly consistent with approximately 45% of the nitrogen staying with the char. This information has partly been used in another study in the CFD modeling of the combustion of black liquor with different levels of lignin removal.
|
|
| 6. |
|
|
| 7. |
- Shoukry, Yasser, et al.
(författare)
-
SMT-Based Observer Design for Cyber-Physical Systems under Sensor Attacks
- 2016
-
Ingår i: 2016 ACM/IEEE 7th International Conference on Cyber-Physical Systems, ICCPS 2016 - Proceedings. - 9781509017720
-
Konferensbidrag (refereegranskat)abstract
- We introduce a scalable observer architecture to estimate the states of a discrete-time linear-time-invariant (LTI) system whose sensors can be manipulated by an attacker. Given the maximum number of attacked sensors, we build on previous results on necessary and sufficient conditions for state estimation, and propose a novel multi-modal Luenberger (MML) observer based on efficient Satisfiability Modulo Theory (SMT) solving. We present two techniques to reduce the complexity of the estimation problem. As a first strategy, instead of a bank of distinct observers, we use a family of filters sharing a single dynamical equation for the states, but different output equations, to generate estimates corresponding to different subsets of sensors. Such an architecture can reduce the memory usage of the observer from an exponential to a linear function of the number of sensors. We then develop an efficient SMT-based decision procedure that is able to reason about the estimates of the MML observer to detect at runtime which sets of sensors are attack-free, and use them to obtain a correct state estimate. We provide proofs of convergence for our algorithm and report simulation results to compare its runtime performance with alternative techniques. Our algorithm scales well for large systems (including up to 5000 sensors) for which many previously proposed algorithms are not implementable due to excessive memory and time requirements. Finally, we illustrate the effectiveness of our algorithm on the design of resilient power distribution systems.
|
|
