An Externally Fired Micro Combined-Cycle, with Largely Adjustable Steam Turbine, in a CHP System

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procedure selecting pumps running as turbines in micro hydro plants

Abstract The authors present a combined method using statistical and numerical models for selecting a pump running as turbine in micro hydro plants. The data of the site (head and capacity) allow calculating two coefficients, C Q and C H , which identify the pump to use successfully as turbine in that place. A one dimensional model, starting from data available on the pumps manufacturers catalogues, reconstructs a virtual geometry of the PAT, then calculates the performances curves, head vs. capacity, efficiency vs. capacity. The procedure has been applied with the aim to select a PAT recovering energy from a pipeline whose characteristic curve is known

performance analysis of a solar only gas micro turbine with mass flow control

Abstract Micro gas turbine applications in concentrating solar field systems is already on industrial stage. The peculiarity of these systems is the possibility to use fossil fuels when solar power source is lacking. It is preferable that the system works in solar-only mode for long time; however, owing to the efficiency loss which occur for low radiation levels, a fuel integration is necessary. This work presents a system which allows to operate with constant efficiency, without the use of fuel for over one fifth of the nominal power rate. It is based on a regenerated micro gas turbine in closed loop configuration. The proposed system includes the solar tower, the heliostats field, the regenerator and a low temperature heat exchanger which cools the working fluid. Finally, two more devices, for the actuation of the proposed control are included: an auxiliary compressor and a bleed valve. The use of air as working fluid has been analyzed, with different values of the base cycle pressure (inlet pressure of the main compressor), which are needed for varying the mass flow flowing in the system. The control of the mass flow rate is mandatory to regulate the gas turbine power, by keeping almost constant the maximum temperature of the thermodynamic cycle when the incident solar radiation changes. In particular, the auxiliary compressor admits fresh air in the cycle when the thermal power received by the sun increases, while the bleed valve discharges it in the atmosphere, when the thermal power decreases. Therefore, the thermodynamic cycle is unchanged and guarantees constant net system efficiency for all the operations conditions. Particular attention is given to the receiver thermal incident flux, heliostat field and solar tower design. The current results are compared with the annual efficiency and energy production of an existing plant in hybrid configuration (solar-fuel).The analysis has been carried out on a commercial gas turbine having a power of 100 kW, sited on Seville town. For the heliostat field analysis, the open source code Solar PILOT has been used, while for the entire plant the code Thermoflex has been employed

Optimization of Heliostat Field in a Thermal Solar Power Plant with an Unfired Closed Joule-Brayton Cycle

Abstract In the last decades, concentrating solar power (CSP) has been gaining increasing attention as a sustainable technology for producing electricity. Nowadays, in the world, 483.6 MWs are produced by CSP plants of which 457 MW are already in commercial stage, whereas the other 430 MWs are under construction. In this paper, a solar tower with an unfired closed Joule-Brayton cycle of 10 MW peak power, located in Seville, is analyzed. The cycle, that employs only atmospheric air, without fuel consumption, relies on the possibility to vary the mean density of the air flowing in the plant. By using an auxiliary compressor and a bleed valve, a variable mass flow rate can be obtained so to keep the temperature at turbine inlet constant. On the other hand, in the concentrated solar plant, the number of installed heliostats can reflect towards the receiver the nominal thermal power, even with reduced values of the DNI. With the increase of the radiation, when the thermal energy flux achieves the limit tolerable by the receiver, a part of heliostats is defocused. On the contrary, in the presence of transients, due, for example, to clouds or in case of low solar radiation, the mirrors will be all, or in part, oriented towards the receiver face, so to keep constant the receiver outlet air temperature at the design value. Both the above mentioned control systems, without any fuel addition, act with the common goal of maintaining constant the air temperature at turbine inlet. However, they intervene at different times: at rated power, heliostats work, while the air flow rate is kept constant at the maximum value; when the nominal conditions are no longer achievable (the DNI values are insufficient), the adjustment is performed through the modulation of the pressure base control system, focusing the entire surface of the mirrors on the receiver. The analysis shows how the interaction between these systems influences the number and size of heliostats to be installed in the solar field. The study of the state of art has demonstrated that, in tower systems currently in operation, without storage, a solar multiple of 1.3 is generally used; our contribution shows how, with the air density control system, this value may be reduced, with consequent benefit on the heliostats cost. The numerical tests have been carried out by using the WINDELSOL software to optimize the heliostat field configuration and the THERMOFLOW, for the thermodynamic analysis

dynamic simulation of the temperature inlet turbine control system for an unfired micro gas turbine in a concentrating solar tower

Abstract In this work, the dynamic performance of a mass flow regulation system, in a concentrating solar tower plant, with unfired closed micro gas turbine, during clouds transient will be presented. The adjustment system operates with the heliostats field control system, in order to control the temperature inlet turbine. To choose the best configuration, the performance of three heliostats sizes, for four Solar Multiple, has been evaluated. The design of the solar field was carried out by means of Solar Pilot, while the numerical models have been developed in Matlab/Simulink. The results show that a particular configuration is suitable for this purpose

Exploiting tumour addiction with a serine and glycine-free diet.

Understanding cancer metabolism is key to unveil the Achilles’ heel of cancer cells and provide novel therapeutic interventions for patients. While the rerouting of metabolic pathways during development1 or cancer transformation and progression2, 3, 4 has been extensively characterised, the exact dynamic of these events, their distribution and frequency in the different tumour types, and the correlation with genetic background remain largely unknown. In a recent article published in Nature, Karen Vousden’s team assesses the effect of serine and glycine dietary restriction in autochthonous mouse tumour models driven by different oncogenes (Maddocks et al, 2017)5, leading to potential area of therapeutic intervention

Semi-Supervised Overlapping Community Finding based on Label Propagation with Pairwise Constraints

Algorithms for detecting communities in complex networks are generally unsupervised, relying solely on the structure of the network. However, these methods can often fail to uncover meaningful groupings that reflect the underlying communities in the data, particularly when those structures are highly overlapping. One way to improve the usefulness of these algorithms is by incorporating additional background information, which can be used as a source of constraints to direct the community detection process. In this work, we explore the potential of semi-supervised strategies to improve algorithms for finding overlapping communities in networks. Specifically, we propose a new method, based on label propagation, for finding communities using a limited number of pairwise constraints. Evaluations on synthetic and real-world datasets demonstrate the potential of this approach for uncovering meaningful community structures in cases where each node can potentially belong to more than one community.Comment: Fix table

Pericardium of the frog, Rana esculenta, is morphologically designed as a lymphatic space

The importance of the pericardium and the pericardial fluid (PF) in the control of cardiac function has emerged over the past few years. Despite the acknowledgment that amphibians are exposed to both dehydration and excessive water accumulation, nothing is known about their pericardial structure and the morphological basis of the PF formation. We have studied the parietal pericardium (PP) morphology in Rana esculenta by electron microscopy. SEM images of the inner surface, which lines the pericardial cavity, revealed the presence of large vesicles and many small circular openings. TEM observations showed that the PP is made up of an inner mesothelial lining, often constituted by two layers of very flat cells lying on a basal membrane and of regularly oriented collagen bundles. The PP outer surface is lined by a layer of flat cells, without a basal membrane. The mesothelial cells had overlapping boundaries with complex intercellular connections and a rich pool of caveolae opened in the direction of both the pericardial cavity and intercellular spaces. These cells indicate an intense intracellular and/or intercellular transfer of fluids and substances. The intraperitoneal injection of the idromineral hormone, Val5-ANG II, induced PP modifications, particularly evident at the level of the structures involved in the transmesothelial traffic. These lymphatic-like traits suggest that the frog PP represents a large lymphatic sac, subject to paracrine-endocrine remodeling, which can actively adjust the PF, influencing the composition and volume of the myocardial interstitial fluid. © 2003 Wiley-Liss, Inc

Antiepileptic Drugs and Suicide: A Systematic Review of Adverse Effects

&lt;b&gt;&lt;i&gt;Background:&lt;/i&gt;&lt;/b&gt; Since the FDA (Food and Drug Administration) report on antiepileptic drugs (AEDs) and suicide risk was released (2008), several studies have been published on this controversial relationship. This systematic review (SR) gives an updated approach to this health issue. &lt;b&gt;&lt;i&gt;Summary:&lt;/i&gt;&lt;/b&gt; We searched 6 databases. We ultimately included 11 publications: 4 cohort studies, 1 case-crossover study, 2 community case-control studies, and 4 SRs. Overall, 1 SR described studies already included; 3 studies reported a 2- to 4-fold overall increase in risk; 1 study reported an increased risk of suicide among epilepsy patients on AEDs with high risk of depression; 1study showed a protective effect among epilepsy patients; 2 studies were conducted with patients with bipolar disorder (1 showed a protective effect, whereas the other showed a 3-fold increase in risk of suicide), and the other 3 studies reported results for single AEDs. Several biases affected the published results. &lt;b&gt;&lt;i&gt;Key Messages:&lt;/i&gt;&lt;/b&gt; There is no clear evidence of an association between the use of AEDs and an increased risk of suicide because of the heterogeneity in the studies at the clinical and methodological level. A future study should cover all indications for use, retrieve information from a healthcare database, and include a defined set of covariates to avoid bias.</jats:p

Body composition study by dual-energy x-ray absorptiometry in familial partial lipodystrophy: finding new tools for an objective evaluation (vol 4, pg 40, 2012)

Rio de Janeiro & Catholic Univ, Inst Estadual Diabet & Endocrinol, Metab Unit, Rio de Janeiro, BrazilUniv Fed Rio de Janeiro, Dept Nutrol, Rio de Janeiro, RJ, BrazilUniversidade Federal de São Paulo, Div Endocrinol, São Paulo, SP, BrazilInst Estadual Diabet & Endocrinol, BR-20211340 Rio de Janeiro, RJ, BrazilUniversidade Federal de São Paulo, Div Endocrinol, São Paulo, SP, BrazilWeb of Scienc