Techno-economic assessment of a solar dish micro gas turbine system

In this thesis a thermo-economic assessment of a stand-alone solar dish MGT power plant is presented. The study aims to develop a fundamental understanding of the impact of the main cycle parameters on plant performances and costs and to evaluate the possibility to incorporate hybridisation and thermal storage, considering technical limitations and economic aspects. Objective have been achieved developing a flexible and modular tool for design and off-design performance evaluation of micro-turbine based solar power plants. This can then be adopted for different layouts and operational strategies. The model was validated against experimental data demonstrating the applicability and accuracy of the model for thermo-economic optimisation purposes. To guarantee modularity and flexibility an object-oriented programming approach, using the software C++, is adopted. Each component is represented using a class made of functions that perform a one dimensional physical design for both design point and off-design performance in addition to a cost function. Results in output from the above-mentioned tool were used to train machine learning algorithms, which were used to perform plant's optimisations considering dissimilar layouts, locations and operational strategies. A multi objective genetic algorithm was adopted as optimisation tool. The objective of the optimisation was to 1mmm1Se the levelised cost of energy of the plant while maxrnusrng the annual po,ver output. Both environmental impact and plant dispachability were considered. As a final outcome of the optimisation: for each considered layout and operationa.l strategy: a candidate point was selected and analysed. Parametric study on possible technological improvements of plants' components was also performed. The proposed optimum plant configurations are shmvn to be advantageous in term of levelised cost of energy, more dispatchable and with a reduced environmental impact

Solvatipn Of Excess Electrons In Supercritical Ammonia

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A quantum molecular dynamics study of aqueous solvation dynamics

Ring polymer molecular dynamics experiments have been carried out to examine effects derived from nuclear quantum fluctuations at ambient conditions on equilibrium and non-equilibrium dynamical characteristics of charge solvation by a popular simple, rigid, water model, SPC/E , and for a more recent, and flexible, q-TIP4P/F model, to examine the generality of conclusions. In particular, we have recorded the relaxation of the solvent energy gap following instantaneous, ±e charge jumps in an initially uncharged Lennard-Jones-like solute. In both charge cases, quantum effects are reflected in sharper decays at the initial stages of the relaxation, which produce up to a ∼20% reduction in the characteristic timescales describing the solvation processes. For anionic solvation, the magnitude of polarization fluctuations controlling the extent of the water proton localization in the first solvation shell is somewhat more marked than for cations, bringing the quantum solvation process closer to the classical case. Effects on the solvation response from the explicit incorporation of flexibility in the water Hamiltonian are also examined. Predictions from linear response theories for the overall relaxation profile and for the corresponding characteristic timescales are reasonably accurate for the solvation of cations, whereas we find that they are much less satisfactory for the anionic case.Fil: Videla, Pablo Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires; ArgentinaFil: Rossky, Peter J.. University of Texas at Austin; Estados UnidosFil: Laria, Daniel Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires; Argentina. Comision Nacional de Energia Atomica. Gerencia Quimica. CAC; Argentin

Techno-economic assessment of a solar dish micro gas turbne system

In this thesis a thermo-economic assessment of a stand alone solar dish MGT power plant is presented. The study aims to develop a fundamental understanding of the impact of the main cycle parameters on plant performances and costs and to evaluate the possibility to incorporate hybridisation and thermal storage, considering technical limitations and economic aspects. Objective have been achieved developing a flexible and modular tool for design and off-design performance evaluation of micro-turbine based solar power plants. This can then be adopted for different layouts and operational strategies. The model was validated against experimental data demonstrating the applicability and accuracy of the model for thermo-economic optimisation purposes. To guarantee modularity and flexibility an object-oriented programming approach, using the software C++, is adopted. Each component is represented using a class made of functions that perform a one-dimensional physical design for both design point and off-design performance in addition to a cost function. Results in output from the above-mentioned tool were used to train machine learning algorithms, which were used to perform plant's optimisations considering dissimilar layouts, locations and operational strategies. A multi objective genetic algorithm was adopted as optimisation tool. The objective of the optimisation was to minimise the levelised cost of energy of the plant while maxmising the annual power output. Both environmental impact and plant dispachability were considered. As a final outcome of the optimisation, for each considered layout and operational strategy, a candidate point was selected and analysed. Parametric study on possible technological improvements of plants' components was also performed. The proposed optimum plant configurations are shown to be advantageous in term of levelised cost of energy, more dispatchable and with a reduced environmental impact.

Computerized adaptive test and decision trees: A unifying approach

In the last few years, several articles have proposed decision trees (DTs) as an alternative to computerized adapted tests (CATs). These works have focused on showing the differences between the two methods with the aim of identifying the advantages of each of them and thus determining when it is preferable to use one method or another. In this article, Tree-CAT, a new technique for building CATs is presented. Unlike the existing work, Tree-CAT exploits the similarities between CATs and DTs. This technique allows the creation of CATs that minimise the mean square error in the estimation of the examinee’s ability level, and controls the item’s exposure rate. The decision tree is sequentially built by means of an innovative algorithmic procedure that selects the items associated with each of the tree branches by solving a linear program. In addition, our work presents further advantages over alternative item selection techniques with exposure control, such as instant item selection or simultaneous administration of the test to an unlimited number of participants. These advantages allow accurate on-line CATs to be implemented even when the item selection method is computationally costly

Integrated Bimodal Fitting for Unilateral CI Users with Residual Contralateral Hearing

Background: The aim of this study was to compare, in users of bimodal cochlear implants, the performance obtained using their own hearing aids (adjusted with the standard NAL-NL1 fitting formula) with the performance using the Phonak Naìda Link Ultra Power hearing aid adjusted with both NAL-NL1 and a new bimodal system (Adaptive Phonak Digital Bimodal (APDB)) developed by Advanced Bionics and Phonak Corporations. Methods: Eleven bimodal users (Naìda CI Q70 + contralateral hearing aid) were enrolled in our study. The users’ own hearing aids were replaced with the Phonak Naìda Link Ultra Power and fitted following the new formula. Speech intelligibility was assessed in quiet and noisy conditions, and comparisons were made with the results obtained with the users’ previous hearing aids and with the Naída Link hearing aids fitted with the NAL-NL1 generic prescription formula. Results: Using Phonak Naìda Link Ultra Power hearing aids with the Adaptive Phonak Digital Bimodal fitting formula, performance was significantly better than that with the users’ own rehabilitation systems, especially in challenging hearing situations for all analyzed subjects. Conclusions: Speech intelligibility tests in quiet settings did not reveal a significant difference in performance between the new fitting formula and NAL-NL1 fittings (using the Naída Link hearing aids), whereas the performance difference between the two fittings was very significant in noisy test conditions

Performance and characteristics of the Newborn Hearing Screening Program in Campania region (Italy) between 2013 and 2019

Purpose: Universal newborn hearing screening (UNHS) in the first month of life is crucial for facilitating both early hearing detection and intervention (EHDI) of significant permanent hearing impairment (PHI). In Campania region, UNHS has been introduced in 2003 by the Regional Council Resolution and started on January 2007. The aim of this paper is to update a previous article describing the performance of the program since its implementation in the period between 2013 and 2019. Methods: A longitudinal retrospective study was carried at the Regional Reference Center III on 350,178 babies born in the analysis period. The paper reports the main results of overall coverage, referral rate, lost-to-follow-up rate,yield for PHI and shall determine various risk factor associations with hearing impairment Results: In Campania region, 318,878 newborns were enrolled at I level, with a coverage rate of 91.06%, 301,818 (86.18%) Well Infant Nurseries (WIN) and 17,060 (5.35%) Neonatal Intensive Care Unit (NICU) babies. PHI was identified in 413 children, 288 (69.73%) bilaterally and 125 (30.26%) unilaterally. The overall cumulative incidence rate of PHI was 1.29 per 1000 live-born infants (95% CI 1.17–1.42) with a quite steady tendency during the whole study period. Conclusions: This study confirms the feasibility and effectiveness of UNHS in Campania region also in a setting with major socioeconomic and health organization restrictions.The program meets quality benchmarks to evaluate the progress of UNHS. Nowadays, it is possible to achieve an early diagnosis of all types of HL avoiding the consequences of hearing deprivation

Tinnitus and equilibrium disorders in COVID-19 patients: preliminary results

Purpose: Tinnitus and equilibrium disorders such as dizziness and vertigo have been reported by patients with COVID-19; however, they have been rarely investigated. The aim of this study was to study the prevalence of subjective tinnitus and dizziness in a sample of COVID-19 patients using an online 10-item close-ended questionnaire. Methods: A multicentric study that included 15 Italian hospitals in different regions was conducted using an online 10-item close-ended questionnaire developed to identify the presence of tinnitus and balance disorders in patients with COVID-19 between May 5 and June 10, 2020. The questionnaire was administered to 185 patients in a period of > 30 – < 60 days after diagnosis of COVID-19; responses were recorded in an online Excel spreadsheet. The questionnaire was composed of three sections: (1) demographic information; (2) presence and characteristics of tinnitus and dizziness after COVID-19 diagnosis; (3) possible association with migraine. Results: Thirty-four patients (18.4%) reported equilibrium disorders after COVID-19 diagnosis. Of these, 32 patients reported dizziness (94.1%) and 2 (5.9%) reported acute vertigo attacks. Forty-three patients (23.2%) reported tinnitus; 14 (7.6%) reported both tinnitus and equilibrium disorders. Conclusion: This study suggests that the presence of subjective otoneurological symptoms such as tinnitus and balance disorders can affect COVID-19 patients; further studies are necessary to investigate the prevalence and pathophysiological mechanisms underlying these subjective symptoms in COVID-19 patients

Sudden olfactory loss as an early marker of COVID-19: a nationwide Italian survey

Purpose: The presence of many asymptomatic COVID-19 cases may increase the risks of disease dissemination, mainly for physicians. There are numerous reports on the frequent findings of sudden anosmia or hyposmia, before or at the same time of the typical COVID-19 symptoms onset. The aim of this study was to verify the association of olfactory impairment and COVID-19, providing a basis for subsequent research in the field of COVID-19 clinical heterogeneity. Methods: We developed a 15-item online questionnaire on “Sudden Olfactory Loss (SOL) and COVID-19” that was administered during March 2020 to Italian general practitioners registered to a social media group. Results: One hundred and eighty responses were received. SOL was identified as a significant sign of infection in COVID-19 patients, mainly aged between 30 and 40 years, even in the absence of other symptoms. SOL was present as an initial symptom in 46.7% of subjects, and in 16.7%, it was the only symptom. Among the COVID-19 confirmed cases, SOL occurred as the only symptom in 19.2% of patients. Conclusion: SOL could represent a possible early symptom in otherwise asymptomatic COVID-19 subjects. Subjects affected by SOL should be considered as potential COVID-19 cases. Level of evidence: 4