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21.
Among a series of parameters, power quality studies are concerned with voltage unbalances, which represent the voltage magnitude and phase deviation from nominal values. In order to determine the influence of the network's parameters on voltage unbalances, and to provide exact solutions to reduce or even eliminate them, the present study develops and presents two methods. First, a sensitivity analysis is used to determine the influence of each parameter, and then analytical solutions are developed in order to provide the changes needed for correction. The quantification index considered is the symmetrical components method.  相似文献   
22.
Optimal Layout of Sewer Systems: A Deterministic versus a Stochastic Model   总被引:1,自引:0,他引:1  
The optimization of a new or partially existing urban drainage system may be modeled as a subproblems sequence of layout and optimal design within the discrete search space. The design optimization, incorporating the optimal selection of the pumping stations, intermediate manholes, pipe sections, and installation depths, for a general system fixed layout in plan, is a high level sequential decision problem which may be efficiently solved deterministically through a multilevel dynamic programming model. The optimal general layout may be selected in a deterministic way by means of a simple economical comparison of all plan solutions having optimized designs, for small to medium sized systems (if the specific restrictions of the applications are appropriately exploited) in practicable computer time. For larger dimension networks, where it is clearly impossible to achieve plan optimization with full enumeration (which is a NP complete), stochastic search models can be used. For the subproblem layout, an effective enumeration model is presented; the results of a stochastic model proposed previously, using simulated annealing for an application example, are compared and discussed in detail.  相似文献   
23.
Background. The tumor immune microenvironment exerts a pivotal influence in tumor initiation and progression. The aim of this study was to analyze the immune context of sporadic and familial adenomatous polyposis (FAP) lesions along the colorectal adenoma–carcinoma sequence (ACS). Methods. We analyzed immune cell counts (CD3+, CD4+, CD8+, Foxp3+, and CD57+), tumor mutation burden (TMB), MHC-I expression and PD-L1 expression of 59 FAP and 74 sporadic colorectal lesions, encompassing adenomas with low-grade dysplasia (LGD) (30 FAP; 30 sporadic), adenomas with high-grade dysplasia (22 FAP; 30 sporadic), and invasive adenocarcinomas (7 FAP; 14 sporadic). Results. The sporadic colorectal ACS was characterized by (1) a stepwise decrease in immune cell counts, (2) an increase in TMB and MHC-I expression, and (3) a lower PD-L1 expression. In FAP lesions, we observed the same patterns, except for an increase in TMB along the ACS. FAP LGD lesions harbored lower Foxp3+ T cell counts than sporadic LGD lesions. A decrease in PD-L1 expression occurred earlier in FAP lesions compared to sporadic ones. Conclusions. The colorectal ACS is characterized by a progressive loss of adaptive immune infiltrate and by the establishment of a progressively immune cold microenvironment. These changes do not appear to be related with the loss of immunogenicity of tumor cells, or to the onset of an immunosuppressive tumor microenvironment.  相似文献   
24.
The aim of the present study was to investigate the influence of an anthocyanin extract (extract I), and two other derivative extracts (extracts II and III), which are being developed aiming to be further applied in the food industry, on intestinal uptake of organic cations. For this purpose, the effect of these compounds on 3H-MPP+ uptake was evaluated in Caco-2 cells (an enterocyte-like cell line derived from a human colonic adenocarcinoma).  相似文献   
25.
In this paper we compare the dynamics on the centre manifold of the solutions of an ill-posed Boussinesq equation with a well-posed version. We show that the dynamics in the centre manifold of the ill-posed equation tracks the dynamics of the well-posed equation. Our results give partial justification to the long-wave perturbation theory.  相似文献   
26.
As JET is developing and testing operational scenarios for higher fusion performance, an increase in pulse disruptivity is being observed. On a deeper analysis, we find that several radiative phenomena play an active role in determining the outcome of the pulse. The analysis is enabled by the use of real-time tomography based on the bolometer diagnostic. Even though plasma tomography is an inverse problem, we use machine learning to train a forward model that provides the radiation profile directly, based on a single matrix multiplication step. This model is used to investigate radiative phenomena including sawtooth crashes, ELMs and MARFE, and their relationship to the radiated power in different regions of interest. In particular, we use real-time tomography to monitor the core region, and to throw an alarm whenever core radiation exceeds a certain threshold. Our results suggest that this measure alone can anticipate a significant fraction of disruptions in the JET baseline scenario.  相似文献   
27.
A lectin was isolated from the saline extract of Artocarpus incisa seed by affinity chromatography on cross-linked Adenanthera pavonina galactomannan in 0.15 M NaCl. The lectin was also retained in a D-gal-agarose resin and had no requirements for divalent metal cations (Ca2+ and Mn2+) for activity. The lectin contains 2.1% of carbohydrate and is characterized by high contents of acidic and hydroxylated amino acids. The lectin presented two protein bands in SDS-PAGE, with M(r) 15.5 and 12 kDa, respectively, and contains no alpha-helix, 64% antiparallel beta-sheet and 21% parallel beta-sheet/beta-turn. When submitted to gel filtration in Superose 12 R (FPLC) and Superdex 75 HR 5/5 (HPLC) columns, the lectin showed an M(r) of 48-49 kDa, suggesting a tetrameric structure.  相似文献   
28.
The aim of this study was to review prior studies that have evaluated the effects of cooking techniques on polyphenol levels and antioxidant activity in vegetables and to release a meta-analysis of the findings. Meta-analysis with a random effect model was conducted using the weighted response ratios (R*) that were calculated for each experiment. Baking (R* = 0.51), blanching (R* = 0.94), boiling (R* = 0.62), microwaving (R* = 0.54) and pressure cooking (R* = 0.47) techniques precipitated significant reductions in the polyphenol levels. Significant decreases in the antioxidant activity levels were noted after baking (R* = 0.45) and boiling (R* = 0.76), while significant increases were observed after frying (R* = 2.26) and steaming (R* = 1.52).  相似文献   
29.
Anthocyanins bioavailability is a major issue regarding their biological effects and remains unclear due to few data available on this matter. This work aimed to evaluate the absorption of anthocyanins at the intestine using Caco‐2 cells. Anthocyanin extract, rich in malvidin‐3‐glucoside, was obtained from red grape skins and tested on Caco‐2 cells. The absorption of anthocyanins, in absence or presence of 1% ethanol, was detected by HPLC/DAD/LC‐MS. Our results showed that this transport was significantly increased in the presence of ethanol especially after 60 min of incubation. In addition, cells that were pretreated for 96 h with anthocyanins (200 μg/mL) showed an increase of their own transport (about 50% increase). Expression of glucose transporters sodium‐dependent glucose transporter 1, facilitative glucose transporters 5, and facilitative glucose transporters 2 was assessed by RT‐PCR. It was found that facilitative glucose transporters 2 expression was increased (60%) in Caco‐2 cells pretreated with anthocyanins, by comparison with controls. When the effect of anthocyanin extract on 3H‐2‐deoxy‐D ‐glucose uptake was tested, an inhibitory effect was observed (about 60% decrease). However, the malvidin aglycone was tested and had no effect. In conclusion, anthocyanins could be absorbed through Caco‐2 cells, and can interfere with their own transport and also with glucose intestinal uptake.  相似文献   
30.
This paper presents the neutron energy spectrum in the central position of a neutron flux trap assembled in the core center of the research nuclear reactor IPEN/MB-01, obtained by an unfolding method. To this end, we have used several different types of activation foils (Au, Sc, Ti, Ni, and plates) which have been irradiated in the central position of the reactor core (setting number 203) at a reactor power level (64.57±2.91 watts). The activation foils were counted by solid-state detector HPGe (high pure germanium detector) (gamma spectrometry). The experimental data of nuclear reaction rates (saturated activity per target nucleus) and a neutron spectrum estimated by a reactor physics computer code are the main input data to get the most suitable neutron spectrum in the irradiation position obtained through SANDBP (spectrum analysis neutron detection code-version Budapest University) code: a neutron spectra unfolding code that uses an iterative adjustment method. the integral neutron flux, (2.41 ± 0.01) × 10^9 n·cm^-2·s^-1 for the thermal The adjustment resulted in (3.85 ± 0.14) × 10^9 n·cm^-2·s^-1 for neutron flux, (1.09 ±0.02) × 10^9n·cm^-2·s^-1 for intermediate neutron flux and (3.41 ± 0.02) × 10^8 n·cm^-2·s^-1 for the fast neutrons flux. These results can be used to verify and validate the nuclear reactor codes and its associated nuclear data libraries, besides, show how much effective it can be that the use of a neutron flux trap in the nuclear reactor core to increase the thermal neutron flux without increase the operation reactor power level. The thermal neutral flux increased 4.04 ± 0.21 times compared with the standard configuration of the reactor core.  相似文献   
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