| 1. |
- Curbis, F, et al.
(författare)
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HIGHLIGHTS FROM THE CONCEPTUAL DESIGN REPORT OF THE SOFT X-RAY LASER AT MAX IV
- 2021
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Ingår i: Proceedings of IPAC2021.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The SXL (Soft X-ray Laser) project developed a conceptual design for a soft X-ray Free Electron Laser (FEL) in the 1-5 nm wavelength range, driven by the existing MAX IV 3 GeV linac. In this contribution we will focus on the FEL operation modes developed for the first phase of the project based on two different linac modes. The design work was supported by the Knut and Alice Wallenberg foundation and by several Swedish universities and organizations (
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| 2. |
- Pirani, S, et al.
(författare)
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START-TO-END STUDY ON LASER AND RF JITTER EFFECTS FOR MAX IV SXL
- 2021
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Ingår i: Proceedings of IPAC2021. ; , s. 844-846
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A Soft X-ray free electron laser (FEL) for the MAX IV Laboratory is currently in the design phase and it will use the existing 3 GeV linac. Present stability limits in the RF and the photocathode laser will affect the performance of the FEL. One of the critical elements for the design of a FEL is to have an estimation on jitter effects of the accelerator parameters on the X-ray radiation. In this regard, we implemented a start-to-end study using Astra, Elegant and Genesis in order to assess possible variations in pulse energy, photon pulse length and spectral width in the Soft X-ray Laser (SXL) radiation. This investigation provides insights on the final SXL performance variation due to RF and laser related jitter affecting the electron beam.
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| 3. |
- Ahmadiannamin, S., et al.
(författare)
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Design of 100 MHz RF cavity for the storage ring of the Iranian Light Source Facility (ILSF)
- 2020
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 981
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Tidskriftsartikel (refereegranskat)abstract
- The Iranian Light Source Facility is a fourth-generation low emittance synchrotron light source under development in Iran. The design and in-house fabrication of RF cavities are key elements of this project. The choice of 100 MHz capacity loaded RF cavities offers many advantages compared to other cavity types due to a simpler geometry, ease of fabrication, and lower costs for manufacturing and RF power system development. Here we present comprehensive simulation studies of these accelerating RF cavities. This includes electromagnetic, mechanical, and thermal calculations. In addition, in the electromagnetic design section, discussions of higher-order modes, their impact on beam instabilities during machine operation and beam loading effects are addressed. Finally, thermomechanical simulation results are presented. The fabrication of a 100 MHz capacity-loaded cavity has started based on the design presented in this article.
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| 4. |
- Pop, M, et al.
(författare)
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ANALYSIS OF THE EFFECT OF ENERGY CHIRP IN IMPLEMENTING EEHG AT SXL
- 2021
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Ingår i: Proceedings of IPAC2021. ; , s. 1566-1569
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- As a part of the efforts to improve the longitudinal coherence in the design of the Soft X-ray FEL (the SXL) at MAX IV, we present a possible implementation of the EEHG harmonic seeding scheme partly integrated into the second bunch compressor of the existing LINAC. A special focus is given to the effect of CSR on the resulting EEHG bunching and on how this unwanted effect might be controlled.
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| 5. |
- Schio, L., et al.
(författare)
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Double Photoionization of Nitrosyl Chloride by Synchrotron Radiation in the 24-70 eV Photon Energy Range
- 2023
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Ingår i: Molecules. - 1420-3049. ; 28:13
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Tidskriftsartikel (refereegranskat)abstract
- The behavior of nitrosyl chloride (ClNO) exposed to ionizing radiation was studied by direct probing valence-shell electrons in temporal coincidence with ions originating from the fragmentation process of the transient ClNO2+. Such a molecular dication was produced by double photoionization with synchrotron radiation in the 24-70 eV photon energy range. The experiment has been conducted at the Elettra Synchrotron Facility of Basovizza (Trieste, Italy) using a light beam linearly polarized with the direction of the polarization vector parallel to the ClNO molecular beam axis. ClNO molecules crossing the photon beam at right angles in the scattering region are generated by effusive expansion and randomly oriented. The threshold energy for the double ionization of ClNO (30.1 & PLUSMN; 0.1 eV) and six dissociation channels producing NO+/Cl+, N+/Cl+, N+/O+, O+/Cl+, ClN+/O+, NO+/Cl2+ ion pairs, with their relative abundance and threshold energies, have been measured.
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| 6. |
- Turrini, D., et al.
(författare)
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Olivine on Vesta as exogenous contaminants brought by impacts : Constraints from modeling Vesta's collisional history and from impact simulations
- 2016
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Ingår i: Icarus. - : Elsevier BV. - 0019-1035. ; 280, s. 328-339
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Tidskriftsartikel (refereegranskat)abstract
- The survival of asteroid Vesta during the violent early history of the Solar System is a pivotal constraint on theories of planetary formation. Particularly important from this perspective is the amount of olivine excavated from the vestan mantle by impacts, as this constrains both the interior structure of Vesta and the number of major impacts the asteroid suffered during its life. The NASA Dawn mission revealed that olivine is present on Vesta's surface in limited quantities, concentrated in small patches at a handful of sites not associated with the two large impact basins Rheasilvia and Veneneia. The first detections were interpreted as the result of the excavation of endogenous olivine, even if the depth at which the detected olivine originated was a matter of debate. Later works raised instead the possibility that the olivine had an exogenous origin, based on the geologic and spectral features of the deposits. In this work, we quantitatively explore the proposed scenario of a exogenous origin for the detected vestan olivine to investigate whether its presence on Vesta can be explained as a natural outcome of the collisional history of the asteroid over the last one or more billion years. To perform this study we took advantage of the impact contamination model previously developed to study the origin and amount of dark and hydrated materials observed by Dawn on Vesta, a model we updated by performing dedicated hydrocode impact simulations. We show that the exogenous delivery of olivine by the same impacts that shaped the vestan surface can offer a viable explanation for the currently identified olivine-rich sites without violating the constraint posed by the lack of global olivine signatures on Vesta. Our results indicate that no mantle excavation is in principle required to explain the observations of the Dawn mission and support the idea that the vestan crust could be thicker than indicated by simple geochemical models based on the Howardite–Eucrite–Diogenite family of meteorites.
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| 7. |
- Dibaji, S. M., et al.
(författare)
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Secure Control of Wide-Area Power Systems : Confidentiality and Integrity Threats
- 2018
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Ingår i: 2018 IEEE Conference on Decision and Control (CDC). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538613955 ; , s. 7269-7274
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Konferensbidrag (refereegranskat)abstract
- A cyber-physical model for wide-area control of power systems is considered, where the state variables of each generator are measured and sent to the cyber-network and the corresponding control inputs are computed distributively. The secure control of such wide-area power systems is considered in the presence of cyber attacks that introduce threats that compromise their integrity and confidentiality. Detection, prevention, and resilience for these attacks and algorithms for accomplishing these goals are proposed. In particular, an algorithm to overcome confidentiality attacks of the underlying control gains is presented. Also proposed is an algorithm for defense against integrity attacks that might take place on the cyber-network. For this purpose, a resilient information retrieval approach is leveraged which recovers the true state variables despite the malicious attacks on both virtual machines and communication links. The retrieved states are then used to detect possible attacks on phasor measurement units (PMU) in the next time-step. Simulation studies are included to validate our proposed approaches.
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| 8. |
- Madhani, H., et al.
(författare)
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Untangling phylogenetic patterns and taxonomic confusion in tribe Caryophylleae (Caryophyllaceae) with special focus on generic boundaries
- 2018
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Ingår i: Taxon. - : Wiley. - 0040-0262 .- 1996-8175. ; 67:1, s. 83-112
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Tidskriftsartikel (refereegranskat)abstract
- Assigning correct names to taxa is a challenging goal in the taxonomy of many groups within the Caryophyllaceae. This challenge is most serious in tribe Caryophylleae since the supposed genera seem to be highly artificial, and the available morphological evidence cannot effectively be used for delimitation and exact determination of taxa. The main goal of the present study was to re-assess the monophyly of the genera currently recognized in this tribe using molecular phylogenetic data. We used the sequences of nuclear ribosomal internal transcribed spacer (ITS) and the chloroplast gene rps16 for 135 and 94 accessions, respectively, representing all 16 genera currently recognized in the tribe Caryophylleae, with a rich sampling of Gypsophila as one of the most heterogeneous groups in the tribe. Phylogenetic trees were reconstructed using maximum parsimony and Bayesian inference methods. The results show that most of the large genera of Caryophylleae are not monophyletic. As a result, we propose a new classification system matching both molecular phylogenetic and morphological evidence. The main taxonomic conclusions include: (1) the description of three new genera, (2) treating five small genera as synonyms, (3) resurrecting the genus Heterochroa with six species, and (4) proposing 23 new combinations plus 2 replacement names at the specific level. As a result, we recognize 14 genera in Caryophylleae. A diagnostic key to all genera of Caryophylleae is provided.
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| 9. |
- Pirani, Atefeh, et al.
(författare)
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Molecular phylogeny of Acanthophyllum (Caryophyllaceae, Caryophylleae), with emphasis on infrageneric classification
- 2014
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Ingår i: Taxon. - 0040-0262. ; 63:3, s. 592-607
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Tidskriftsartikel (refereegranskat)abstract
- Despite being one of the larger genera of Caryophyllaceae with about 60 cushion-forming subshrubby species, Acanthophyllum is represented poorly in previous molecular phylogenetic studies. The genus is an important component of the subalpine steppe flora in Central to Southwest Asia. Although the placement of Acanthophyllum in the tribe Caryophylleae and a close relationship to Allochrusa has already been suggested, the monophyly of the genus and its infrageneric taxa, as well as its relation to other closely related genera, have not been addressed. We have assembled datasets of nuclear ribosomal internal transcribed spacer (ITS) sequences and intron sequences of the chloroplast gene rps16 for 47 Acanthophyllum species and 63 species of 11 additional genera from Caryophylleae. Phylogenetic analyses were performed using maximum parsimony, maximum likelihood and Bayesian methods. Our analysis suggests that Allochrusa, Diaphanoptera, Ochotonophila and Scleranthopsis are nested within Acanthophyllum but that the traditionally recognized sections of Acanthophyllum are monophyletic after reassignment of a few species. Emarginate petals may be a synapomorphy for one of the two basal clades of Acanthophyllum. Moreover, non-monophyly of the genera Gypsophila and Diaphanoptera is suggested by the present study. The age of the crown clade of Acanthophyllum s.l. is estimated to be 11.1 Ma by *BEAST species tree analysis.
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| 10. |
- Pirani, A., et al.
(författare)
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Phylogeny ofAcanthophyllums.l. revisited: An update on generic concept and sectional classification
- 2020
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Ingår i: Taxon. - : Wiley. - 0040-0262 .- 1996-8175. ; 69:3, s. 500-514
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Tidskriftsartikel (refereegranskat)abstract
- The generic boundary of the broadly definedAcanthophyllums.l., the third-largest genus of the tribe Caryophylleae (Caryophyllaceae), has been a subject of taxonomic confusion.Acanthophyllums.l. now includes five minor genera previously recognized as independent. Among these small genera, the inclusion ofAllochrusa,Ochotonophila, andScleranthopsiswithinAcanthophyllums.l. was confirmed by previous molecular studies, while the positions ofDiaphanopteraandKuhitangiaremained uncertain. We have performed an updated molecular study ofAcanthophyllums.l. including an increased sampling of the genera and sections assigned to this group, using intron sequences of the chloroplast generps16and nuclear ribosomal internal transcribed spacer (ITS) sequences.Cyathophylla,Heterochroa, andSaponariawere chosen as outgroups for performing phylogenetic analyses using maximum likelihood and Bayesian methods. The present results suggest that, in addition to the genera mentioned above, bothDiaphanopteraandKuhitangiashould also be synonymized withinAcanthophyllum. SectionsDiaphanoptera,KuhitangiaandPseudomacrostegiaare introduced as new infrageneric taxa withinAcanthophyllum.Our results also indicate that some annual species ofSaponariaare closely related toAcanthophyllum.
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| 11. |
- Pirani, A., et al.
(författare)
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Systematic significance of seed morphology in Acanthophyllum (Caryophyllaceae: tribe Caryophylleae) in Iran
- 2019
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Ingår i: Phytotaxa. - : Magnolia Press. - 1179-3155 .- 1179-3163. ; 387:2, s. 105-118
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Tidskriftsartikel (refereegranskat)abstract
- Acanthophyllum, with ca. 90 spiny cushion-forming species, is one of the largest genera of Caryophyllaceae. Although taxonomic utility of seed morphology has already been highlighted in different genera of Caryophyllaceae, the systematic value of seed characters in Acanthophyllum has not been adequately addressed. In order to evaluate the application of seed morphology in infrageneric classification of Acanthophyllum, we surveyed seed characters in the five Iranian sections of Acanthophyllum. Seed morphology of 32 accessions of Acanthophyllum representing 21 species and four sections were investigated using scanning electron microscopy. Seed morphological characters of two species from one additional section were included based on previous studies in the Caryophyllaceae. Seeds in the majority of examined species are oblong in outline. Five types of seed surface can be considered: reticulate, reticulate-papillate, colliculate, colliculate-papillate, and colliculate-columellate. Papillae type is a reliable character for separation of certain natural groups within Acanthophyllum. Seed features provided strong evidences for separating sections, especially the following ones: Acanthophyllum, Macrostegia and Pleiosperma, whose seeds showed a high degree of uniformity among the sampled species. Morphological characteristics of seeds were less useful for discriminating Acanthophyllum species. While seed characters are consistent within individual populations, they can vary among different populations of an individual species. Our results show that variation in seed morphological characters are in agreement with phylogenetic patterns within Acanthophyllum.
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| 12. |
- Pirani, M., et al.
(författare)
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Impact of Network Topology on the Resilience of Vehicle Platoons
- 2022
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Ingår i: IEEE transactions on intelligent transportation systems (Print). - : Institute of Electrical and Electronics Engineers (IEEE). - 1524-9050 .- 1558-0016. ; 23:9, s. 15166-15177
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a comprehensive study on the impact of information flow topologies on the resilience of distributed algorithms that are widely used for estimation and control in vehicle platoons. In the state of the art, the influence of information flow topology on both internal and string stability of vehicle platoons has been well studied. However, understanding the impact of information flow topology on cyber-security tasks, e.g., attack detection, resilient estimation and formation algorithms, is largely open. By means of a general graph theory framework, we study connectivity measures of several platoon topologies and we reveal how these measures affect the ability of distributed algorithms to reject communication disturbances, to detect cyber-attacks, and to be resilient against them. We show that the traditional platoon topologies relying on interaction with the nearest neighbor are very fragile with respect to performance and security criteria. On the other hand, appropriate platoon topologies, namely k-nearest neighbor topologies, are shown to fulfill desired security and performance levels. The framework we study covers undirected and directed topologies, ungrounded and grounded topologies, or topologies on a line and on a ring. We show that there is a trade-off in the network design between the robustness to disturbances and the resilience to adversarial actions. Theoretical results are validated via simulations.
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| 13. |
- Pirani, S., et al.
(författare)
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Consequences of planetary migration on the minor bodies of the early solar system
- 2019
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 623
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Tidskriftsartikel (refereegranskat)abstract
- Pebble accretion is an efficient mechanism that is able to build up the core of the giant planets within the lifetime of the protoplanetary disc gas-phase. The core grows via this process until the protoplanet reaches its pebble isolation mass and starts to accrete gas. During the growth, the protoplanet undergoes a rapid, large-scale, inward migration due to the interactions with the gaseous protoplanetary disc. In this work, we have investigated how this early migration would have affected the minor body populations in our solar system. In particular, we focus on the Jupiter Trojan asteroids (bodies in the coorbital resonance 1:1 with Jupiter, librating around the L4 and L5 Lagrangian points called, respectively, the leading and the trailing swarm) and the Hilda asteroids. We characterised their orbital parameter distributions after the disc dispersal and their formation location and compare them to the same populations produced in a classical in situ growth model. We find that a massive and eccentric Hilda group is captured during the migration from a region between 5 and 8 au and subsequently depleted during the late instability of the giant planets. Our simulations also show that inward migration of the giant planets always produces a Jupiter Trojans' leading swarm more populated than the trailing one, with a ratio comparable to the current observed Trojan asymmetry ratio. The in situ formation of Jupiter, on the other hand, produces symmetric swarms. The reason for the asymmetry is the relative drift between the migrating planet and the particles in the coorbital resonance. The capture happens during the growth of Jupiter's core and Trojan asteroids are afterwards carried along during the giant planet's migration to their final orbits. The asymmetry and eccentricity of the captured Trojans correspond well to observations, but their inclinations are near zero and their total mass is three to four orders of magnitude higher than the current population. Future modelling will be needed to understand whether the dynamical evolution of the Trojans over billions of years will raise the inclinations and deplete the masses to observed values.
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| 14. |
- Rogelj, Joeri, et al.
(författare)
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Mitigation pathways compatible with 1.5°C in the context of sustainable development
- 2018
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Ingår i: Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty. ; , s. 93-174
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Bokkapitel (refereegranskat)
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| 15. |
- Turrini, D., et al.
(författare)
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The contribution of the ARIEL space mission to the study of planetary formation
- 2018
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Ingår i: Experimental Astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 46:1, s. 45-65
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Tidskriftsartikel (refereegranskat)abstract
- The study of extrasolar planets and of the Solar System provides complementary pieces of the mosaic represented by the process of planetary formation. Exoplanets are essential to fully grasp the huge diversity of outcomes that planetary formation and the subsequent evolution of the planetary systems can produce. The orbital and basic physical data we currently possess for the bulk of the exoplanetary population, however, do not provide enough information to break the intrinsic degeneracy of their histories, as different evolutionary tracks can result in the same final configurations. The lessons learned from the Solar System indicate us that the solution to this problem lies in the information contained in the composition of planets. The goal of the Atmospheric Remote-Sensing Infrared Exoplanet Large-survey (ARIEL), one of the three candidates as ESA M4 space mission, is to observe a large and diversified population of transiting planets around a range of host star types to collect information on their atmospheric composition. ARIEL will focus on warm and hot planets to take advantage of their well-mixed atmospheres, which should show minimal condensation and sequestration of high-Z materials and thus reveal their bulk composition across all main cosmochemical elements. In this work we will review the most outstanding open questions concerning the way planets form and the mechanisms that contribute to create habitable environments that the compositional information gathered by ARIEL will allow to tackle.
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