1,720,978 research outputs found
Effects of Different Blade Loading Strategies Applied to Low Specific Speed Tube-Axial Fans
No full textCurrent industrial fans belonging to the tube-axial type offer the best performance for specific speeds higher than 6. For specific speed higher than 7.5, it is widely demonstrated that the performance requirements and efficiency of fans designed using the free-vortex blade load distribution can be matched, when not exceeded, by using other blade load distributions, also with advantage in terms of fan size reduction. On the other hand, the large number of free-vortex designs populating the vane-axial industrial fan type, suggests that the advantage associated with blade load distributions other than free-vortex reduces as specific speed decreases and vanishes at specific speeds lower than 6. This work presents and compares three fan designs conceived by the authors for specific speed approximately equal to 4.3. The fans feature hub-to-tip ratio equal to 0.5 and differ to each other only in the blade load distribution that varies from free-vortex to rigid-body, passing through the constant-swirl one. The aims of the work are to quantify the pros and cons associated with the considered blade loading distributions, to identify the blade loading concept best suited to the range of specific speeds where hub-to-tip ratios equal to 0.5 are recommended for tube-axial fans and, to assess the capability of the design method originally suggested by the authors for fans with low hub-to-tip ratio. For this purpose, CFD-RANS analyses were carried out to preliminarily characterise all three proposed designs and identify the most efficient one. The most promising solution was manufactured by rapid prototyping, in the 315mm diameter size, and tested according to ISO 5801. The results demonstrate that the constant-swirl blade loading distribution offers good performance even at specific speeds close to the lower extreme of the usual tube-axial industrial fans application range and can be successfully designed using the improved version of the authors’ method presented here
Energy, economic and environmental benefits of Demand Response for improving building energy flexibility
Full text linkThe increasing penetration of intermittent renewable sources in power generation at local and building-level poses growing issues in balancing generation and demand. To avoid imbalances, it is therefore necessary to ensure adequate levels of flexibility in the building energy system. This can be done both on the generation side, through the coupling of different energy carriers (cogeneration, power-to-heat solutions) and/or the integration of storage systems, and on the demand side, through smart “demand response” programs. This paper considers a tourist facility located in central Germany as a case study to evaluate the energy, economic and environmental benefits that can be obtained from the application of appropriate demand response strategies. The electrical demand data of the facility are monitored at both aggregate and individual load levels and made available by means of a cloud platform. The facility includes two stationary combined heat and power internal combustion engines powered by natural gas and a photovoltaic system. The results show how, thanks to appropriate load management, it is possible, on the one hand, to increase the self-consumption of PV-generated energy and, on the other hand, to keep more constant the load of the engines, which can therefore operate with better efficiencies. This results in both a reduction in energy expenses and a decrease in carbon dioxide emissions attributable to the building
Integrated design and operation optimization of multi-energy systems including energy networks
Full text linkA multi-energy system is composed of four main subsystems: i) energy conversion, ii) energy transportation, iii) energy supply, and iv) energy storage. Recent works in the literature dealing with the design and operation optimization of multi-energy systems usually include only one of the above-mentioned subsystems at a time and neglect the others or consider them as constraints imposed a priori. That kind of approach may lead to near optimal system configurations. In fact, the global optimum can only be achieved by the synthesis, design and operation optimization of the system in its entirety. Here, a mixed integer linear programming (MILP) approach is proposed to simultaneously optimize the size of the energy conversion and storage plants, the capacity of the energy networks, and the operation of the whole multi-energy system. The objective function consists in minimizing the life cycle cost of the system while imposing an upper bound on greenhouse gas emissions. Moreover, this upper..
A multi-criteria approach to optimize the design-operation of Energy Communities considering economic-environmental objectives and demand side management
Full text linkTowards a Unified Modelling Approach for Optimizing the Energy System of the Society
No full textThe increasing complexity of energy systems, made greater by the use of renewable sources and associated
storage systems, increases the need of models capable of predicting the best evolution of the energy system of
domestic or industrial districts, cities, regions, countries, etc. toward forms that are more in harmony with the
natural processes and make sustainable development for future generations.
The purpose of this paper is to illustrate, with examples of applications, how any forecasting regarding the best
management or installation of new energy conversion or storage capacity requires a comprehensive view.
Thus, it cannot disregard an integrated modeling of the conversion processes taking place in its generation and
storage units and distribution networks, as well as of a correct way to predict the uncertain availability of
energy sources and energy consumption of the users. Such modeling must be accurate, but at the same time
simple, given the very large number of variables involved. If carbon emission reduction is acknowledged as a
necessary goal, it cannot be separated from the necessary pursuit of parallel goals, such as maximizing
efficiency and minimizing costs. The optimization approach must therefore be multi-objective since the "best
for a society" requires that many aspects be considered simultaneously. From this point of view, the paper does
not pretend to give definitive answers but aims to demonstrate with application examples how, given one or
more objective functions, the integrated optimization enables the identification of priority choices to be made
in system design and operation for a better transition to a more decarbonized system
Vitamin D-3 affects differentiation, maturation, and function of human monocyte-derived dendritic cells
No full textWe studied the effects of 1 alpha,25-dihydroxyvitamin D-3 (1 alpha,25-(OH)(2)D-3) on differentiation, maturation, and functions of dendritic cells (DC) differentiated from human monocytes in vitro in the presence of GM-CSF and IL-4 for 7 days. Recovery and morphology were not affected by 1 alpha,25-(OH)(2)D-3 up to 100 nM, DC differentiated in the presence of 10 nM 1 alpha,25-(OH)(2)D-3 (D-3-DC) showed a marked decrease in the expression of CD1a, while CD14 remained elevated. Mannose receptor and CD32 were significantly increased, and this correlated with an enhancement of endocytic activity. Costimulatory molecules such as CD40 and CD86 were slightly decreased or nonsignificantly affected (CD80 and MHC II). However, after induction of De maturation with LPS or incubation with CD40 ligand-transfected cells, D-3-DC showed marginal increases in MHC I, MHC II, CD80, CD86, CD40, and CD83, The accessory cell function of D-3-DC in classical MLR was also inhibited. Moreover, allogeneic T cells stimulated with D-3-DC were poor responders in a second MLR to untreated DC from the same or an unrelated donor, thus indicating the onset of a nonspecific hyporesponsivity. In conclusion, our data suggest that 1 alpha,25-(OH)(2)D-3 may modulate the immune system, acting at the very first step of the immune response through the inhibition of DC differentiation and maturation into potent APC
NK cell activation by dendritic cells is dependent on LFA-1-mediated induction of calcium-calmodulin kinase II: inhibition by HIV-1 Tat C-terminal domain.
No full textConstitutive overexpression of CDC25A in primary human mammary epithelial cells results in both defective DNA damage response and chromosomal breaks at fragile sites
No full textCDC25A phosphatase, an essential component of the cell cycle machinery, is also a key player in integrating the specific signals of checkpoint control in response to DNA damage. There are several lines of evidence that indicate a role for CDC25A in cancer (level opment, consistent with the fact that its overexpression is detected in human cancers. In particular we previously reported that CDC25A is overexpressed also in early breast carcinoma. Recent data suggest that oncogene activation during early stages of tumor development causes DNA replication stress resulting in the induction of DNA damage response (DDR) and that the selection of cells defecting in their DDR could lead to malignant progression. To address how CDC25A overexpression contributes to breast cancer development we established it cell model in which CDC25A was constitutively overexpressed in hTERT-immortalized primary human mammary epithelial cells. At the earliest passages following CDC25A transduction we observed DDR signs associated with unscheduled DNA replication origins. In the latest passages DDR was significantly impaired and, even after ionizing radiation exposition, cells failed to induce G1 and G2 checkpoints; moreover DNA replication stress conditions, such as aphidicolin treatment, highlighted increased fragile site breakages and destabilized chromosomes Just in these latest passages cells. Our data suggest that CDC25A overexpression, pushing the cell through the cell cycle transitions, induces DDR alterations that might enhance genomic instability. (C) 2008 Wiley-Liss, Inc. OI Maestro, Roberta/0000-0002-6642-5592 ZR 0 ZS 0 Z8 1CDC25A phosphatase, an essential component of the cell cycle machinery, is also a key player in integrating the specific signals of checkpoint control in response to DNA damage. There are several lines of evidence that indicate a role for CDC25A in cancer development, consistent with the fact that its overexpression is detected in human cancers. In particular we previously reported that CDC25A is overexpressed also in early breast carcinoma. Recent data suggest that oncogene activation during early stages of tumor development causes DNA replication stress resulting in the induction of DNA damage response (DDR) and that the selection of cells defecting in their DDR could lead to malignant progression. To address how CDC25A overexpression contributes to breast cancer development we established a cell model in which CDC25A was constitutively overexpressed in hTERT-immortalized primary human mammary epithelial cells. At the earliest passages following CDC25A transduction we observed DDR signs associated with unscheduled DNA replication origins. In the latest passages DDR was significantly impaired and, even after ionizing radiation exposition, cells failed to induce G1 and G2 checkpoints; moreover DNA replication stress conditions, such as aphidicolin treatment, highlighted increased fragile site breakages and destabilized chromosomes just in these latest passages cells. Our data suggest that CDC25A overexpression, pushing the cell through the cell cycle transitions, induces DDR alterations that might enhance genomic instability
- …
