Opin vísindi
Opin vísindi er varðveislusafn vísindaefnis og doktorsritgerða í opnum aðgangi á vegum íslenskra háskóla og Landsbókasafns Íslands - Háskólabókasafns.
Opinn aðgangur að rannsóknaniðurstöðum er í samræmi við 10. gr. laga nr. 3/2003 um opinberan stuðning við vísindarannsóknir sem og kröfur innlendra og erlendra rannsóknasjóða. Markmiðið með opnum aðgangi er að niðurstöður rannsókna séu aðgengilegar sem flestum óhindrað og án endurgjalds á rafrænu formi. Vistun í varðveislusafninu er varanleg og ætlað að tryggja aðgang að vísindaefni íslenskra háskóla í opnum aðgangi um ókomna tíð. Varðveislusafnið Opin vísindi er tengt við rannsóknagáttina IRIS og rannsóknaniðurstöður í opnum aðgangi sem eru skráðar í IRIS eru um leið vistaðar og gerðar aðgengilegar til framtíðar í varðveislusafninu. Með því að safna þessu efni saman í eitt safn verður aðgangur að því einfaldur og þægilegur fyrir alla sem vilja kynna sér það og geta þannig notið þess öfluga vísindastarfs sem fram fer í háskólum landsins.
Varðveislusafnið er OpenAIRE / OpenAIREplus samhæft og samrýmist kröfum sem gerðar eru um birtingu rannsóknaniðurstaðna úr verkefnum sem styrkt eru úr evrópsku rannsóknaáætlununum FP7 og H2020.
Varðveislusafnið notar opna hugbúnaðinn DSpace.
Opinn aðgangur að rannsóknaniðurstöðum er í samræmi við 10. gr. laga nr. 3/2003 um opinberan stuðning við vísindarannsóknir sem og kröfur innlendra og erlendra rannsóknasjóða. Markmiðið með opnum aðgangi er að niðurstöður rannsókna séu aðgengilegar sem flestum óhindrað og án endurgjalds á rafrænu formi. Vistun í varðveislusafninu er varanleg og ætlað að tryggja aðgang að vísindaefni íslenskra háskóla í opnum aðgangi um ókomna tíð. Varðveislusafnið Opin vísindi er tengt við rannsóknagáttina IRIS og rannsóknaniðurstöður í opnum aðgangi sem eru skráðar í IRIS eru um leið vistaðar og gerðar aðgengilegar til framtíðar í varðveislusafninu. Með því að safna þessu efni saman í eitt safn verður aðgangur að því einfaldur og þægilegur fyrir alla sem vilja kynna sér það og geta þannig notið þess öfluga vísindastarfs sem fram fer í háskólum landsins.
Varðveislusafnið er OpenAIRE / OpenAIREplus samhæft og samrýmist kröfum sem gerðar eru um birtingu rannsóknaniðurstaðna úr verkefnum sem styrkt eru úr evrópsku rannsóknaáætlununum FP7 og H2020.
Varðveislusafnið notar opna hugbúnaðinn DSpace.
Nýlega bætt við
Sequential domain patching for computationally feasible multi-objective optimization of expensive electromagnetic simulation models
(2016) Bekasiewicz, Adrian; Koziel, Slawomir; Leifsson, Leifur; Department of Engineering
In this paper, we discuss a simple and efficient technique for multi-objective design optimization of multi-parameter microwave and antenna structures. Our method exploits a stencil-based approach for identification of the Pareto front that does not rely on population-based metaheuristic algorithms, typically used for this purpose. The optimization procedure is realized in two steps. Initially, the initial Pareto-optimal set representing the best possible trade-offs between conflicting objectives is obtained using low-fidelity representation (coarsely-discretized EM model simulations) of the structure at hand. This is realized by sequential construction and relocation of small design space segments (patches) in order to create a path connecting the extreme Pareto front designs identified beforehand. In the second step, the Pareto set is refined to yield the optimal designs at the level of the high-fidelity electromagnetic (EM) model. The appropriate number of patches is determined automatically. The approach is validated by means of two multi-parameter design examples: a compact impedance transformer, and an ultra-wideband monopole antenna. Superiority of the patching method over the state-of-the-art multi-objective optimization techniques is demonstrated in terms of the computational cost of the design process.
Cost-efficient microwave design optimization using adaptive response scaling
(2016) Koziel, Slawomir; Bekasiewicz, Adrian; Leifsson, Leifur; Department of Engineering
In this paper, a novel technique for cost-efficient design optimization of microwave structures has been proposed. Our approach exploits an adaptive response scaling that ensures good alignment between an equivalent circuit (used as an underlying low-fidelity model) and an electromagnetic (EM) simulation model of the structure under design. As the adaptive scaling tracks the low-fidelity model changes both in terms of frequency and the response level, it exhibits better generalization capability than traditional (e.g., space mapping) surrogates. This translates into improved design reliability and reduced design cost. Our methodology is demonstrated using two examples of microstrip filters and compared to several variations of conventional space mapping.
Cognitive impairment in testicular cancer survivors 2 to 7 years after treatment
(2015-10-31) Amidi, Ali; Wu, Lisa M.; Pedersen, Anders Degn; Mehlsen, Mimi; Pedersen, Christina Gundgaard; Rossen, Philip; Agerbæk, Mads; Zachariae, Robert; Department of Psychology
Purpose: The aim of the present study was to determine the prevalence of cognitive impairment (CI) in a group of testicular (TC) survivors by comparing their neuropsychological test scores with normative data and to assess their performance in specific cognitive domains. Methods: Seventy-two TC survivors were evaluated 2 to 7 years post-treatment with a neuropsychological test battery that assessed multiple cognitive domains—attention and working memory, processing speed, verbal fluency, learning and memory, and executive functioning. Test scores were compared with normative data, and CI status was calculated for each participant. Results: In group-level analyses, survivors exhibited significantly impaired scores on a majority (9/12) of the neuropsychological outcomes (p < 0.01). In individual-level analyses, 62.5 % of the survivors were classified as having CI, significantly exceeding the expected normative frequency of 25 % (binomial test: p < 0.001). In particular, CI was observed in multiple outcomes related to verbal learning and memory (29 to 33 % of participants), visual learning and memory (14–28 %), processing speed (8–24 %), executive functioning (17 %), and attention and working memory (4–15 %). No association was found between treatment modality (surgery ± chemotherapy) and CI. Conclusions: The prevalence of CI in TC survivors was unexpectedly high, with survivors performing significantly worse than expected on a majority of the neuropsychological outcomes. While the findings are preliminary in nature, they still have important implications for the diagnosis and treatment of CI in TC survivors.
Groin hernia surgery in northern Ghana - Humanitarian mission of Polish surgeons in Tamale
(2015-03-01) Mitura, Kryspin; Kozieł, Sławomir; Pasierbek, Michał; Department of Engineering
Availability of surgical care in Africa is severely limited. This is due to the lack of surgeons and a small number of public hospitals. Only 25 out of 100,000 patients with inguinal hernia undergo a surgical treatment. As many as 65% of inguinal hernia repairs are performed urgently because of incarceration. Among patients with incarceration who do not reach the hospital there is recorded as many as 87 deaths per 100 cases. In order to improve the availability of treatment of inguinal hernia in Africa, humanitarian medical missions involving surgeons from Europe are organized. During regular visits to selected centers in Africa, they also carry out intensified treatment of patients and training of the local staff. The aim of the study was to present the experience of Polish surgeons from the humanitarian medical mission in Tamale in northern Ghana undertaken in fall of 2014. Material and methods. Surgical repair was performed in 87 patients (74 men - 85% and 13 women - 15%) between the ages of 26 to 70 years (mean 52.8 years; SD 10.3), who underwent a total of 98 inguinal hernia repairs under local anesthesia. Results. Lichtenstein procedure was performed in 93 and Desarda technique in 5 patients. Patients reported the long-term presence of hernia symptoms - from one to 7 years (mean 3.4 years, SD 1.4). In most patients, hernia occurred more than 3 years earlier (61 patients; 70%). There were no intraoperative complications. All patients were discharged the next day after surgery. There was one wound infection in postoperative period which required mesh explantation. Conclusions. Inguinal hernia commonly found in Ghana is a major issue for the inefficient health care system. Humanitarian medical missions can help to improve the treatment results, as long as they are carried out periodically and allow for training of local personnel. Scarce equipment of medical facilities in Ghana is not a significant difficulty in performing the Lichtenstein repair under the local anesthesia.
Multi-objective design optimization of planar Yagi-Uda antenna using physics-based surrogates and rotational design space reduction
(2015) Koziel, Slawomir; Bekasiewicz, Adrian; Leifsson, Leifur; Department of Engineering
A procedure for low-cost multi-objective design optimization of antenna structures is discussed. The major stages of the optimization process include: (i) an initial reduction of the search space aimed at identifying its relevant subset containing the Pareto-optimal design space, (ii) construction-using sampled coarse-discretization electromagnetic (EM) simulation data-of the response surface approximation surrogate, (iii) surrogate optimization using a multi-objective evolutionary algorithm, and (iv) the Pareto front refinement. Our optimization procedure is demonstrated through the design of a planar quasi Yagi-Uda antenna. The final set of designs representing the best available trade-offs between conflicting objectives is obtained at a computational cost corresponding to about 172 evaluations of the high-fidelity EM antenna model.
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- University of Iceland
- University of Akureyri
- Bifröst University
- Hólar University College
- IRIS
- Agricultural University of Iceland
- National and University Library of Iceland
- Iceland University of the Arts