7,164 research outputs found

    From Textbook Tradition to Time-Saving Textese

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    The Creativity Journey

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    Diagnosis and Repair for Synthesis from Signal Temporal Logic Specifications

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    We address the problem of diagnosing and repairing specifications for hybrid systems formalized in signal temporal logic (STL). Our focus is on the setting of automatic synthesis of controllers in a model predictive control (MPC) framework. We build on recent approaches that reduce the controller synthesis problem to solving one or more mixed integer linear programs (MILPs), where infeasibility of a MILP usually indicates unrealizability of the controller synthesis problem. Given an infeasible STL synthesis problem, we present algorithms that provide feedback on the reasons for unrealizability, and suggestions for making it realizable. Our algorithms are sound and complete, i.e., they provide a correct diagnosis, and always terminate with a non-trivial specification that is feasible using the chosen synthesis method, when such a solution exists. We demonstrate the effectiveness of our approach on the synthesis of controllers for various cyber-physical systems, including an autonomous driving application and an aircraft electric power system

    Considerations on the preliminary sizing of electrical machines with hairpin windings

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    Although the standard preliminary sizing of electrical machines equipping random windings is well consolidated and is worldwide acknowledged to be a good starting point for the design, there is no proof of accuracy and confidence when it comes to hairpin windings. This winding technology is gaining extensive attention due to its inherently high slot fill factor, good heat dissipation, strong rigidity, and short end-windings. These features make hairpin windings a potential candidate for some traction application to enhance power and/or torque densities. In this paper, a comparative design is done using the classical sizing tools available in literature between two surface-mounted permanent magnet synchronous machines, one featuring a random winding and one with a hairpin layout. The study aims at highlighting the hairpin winding challenges at high frequency operations and at showing limits of applicability of these standard approaches when applied to this technology. For verification purposes, finite element evaluations are also performed

    Investigation of the Temperature Effects on Copper Losses in Hairpin Windings

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    Today, an extensive electrification is occurring in all industrial sectors, with a special interest seen in the automotive and aerospace industries. The electric motor, surely, is one of the main actors in this context, and an ever-increasing effort is spent with the aim of improving its efficiency and torque density. Hairpin windings are one of the recent technologies which are implemented onto the stator of the electric motor. Compared to conventional random windings, it inherently features lower DC resistance, higher fill factor, better thermal performance, improved reliability, and an automated manufacturing process. However, its bottleneck is the high ohmic losses at high-frequency operations due to skin and proximity effects (AC losses), resulting in a negative impact on the temperature map of the machine. Nevertheless, while it is well-known that DC losses increase linearly with the operating temperatures, the AC losses trend needs further insight. This paper demonstrates that operating the machine at higher temperatures could be beneficial for overall efficiency, especially at high-frequency operations. This suggests that a paradigm shift is required for the design of electric motors equipped with hair-pin windings, which should therefore focus on a temperature-oriented approach. In addition, the effect of the rotor topology on AC losses, which is often overlooked, is also considered in this paper. The combination of these effects is used to carry out observations and, eventually, to provide design recommendations. Finite element electromagnetic and thermal evaluations are performed to prove the findings of this research

    The prognostic value of stromal and epithelial periostin expression in human breast cancer: Correlation with clinical pathological features and mortality outcome

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    open6noBackground: PN is a secreted cell adhesion protein critical for carcinogenesis. In breast cancer, it is overexpressed compared to normal breast, and a few reports suggest that it has a potential role as a prognostic marker. Methods: Tumour samples obtained at the time of mastectomy from 200 women followed for a median time of 18.7 years (range 0.5-29.5 years) were investigated through IHC with a polyclonal anti-PN antibody using tissue microarrays. Epithelial and stromal PN expression were scored independently according to the percentage of coloured cells; the 60th percentile of PN epithelial expression, corresponding to 1 %, and the median value of PN stromal expression, corresponding to 90 %, were used as arbitrary cut-offs. The relationships between epithelial and stromal PN expression and clinicalpathological features, tumour phenotype and the risk of mortality following surgery were analysed. Appropriate statistics, including the Fine and Gray competing risk proportional hazard regression model, were used. Results: The expression of PN in tumour epithelial cells was significantly lower than that which was observed in stromal cells (p < 0.000). No specific association between epithelial or stromal PN expression and any of the clinicalpathological parameters analysed was found as it was observed in respect to mortality when these variables were analysed individually. However, when both variables were considered as a function of the other one, the expression of PN in the stromal cells maintained a statistically significant predictive value with respect to both all causes and cancerspecific mortality only in the presence of high epithelial expression levels. No significant differences in either all causes or BCa-specific mortality rates were shown according to epithelial expression for tumours displaying higher stromal PN expression rates. However, the trends were opposite for the higher stromal values and the patients with high epithelial expression levels denoted the group with the worst prognosis, while higher epithelial values in patients with lower stromal expression levels denoted the group with the best prognosis, suggesting that PN epithelial/stromal interactions play a crucial role in breast carcinogenesis, most likely due to functional cross-talk between the two compartments. On the basis of PN expression in both compartments, we defined 4 subgroups of patients with different mortality rates with the group of patients characterized by positive epithelial and low stromal PN expression cells showing the lowest mortality risk as opposed to the groups of patients identified by a high PN expression in both cell compartments or those identified by a low or absent PN expression in both cell compartments showing the worst mortality rates. The differences were highly statistically significant and were also retained after multiparametric analysis. Competing risk analysis demonstrated that PN expression patterns characterizing each of previous groups are specifically associated with cancer-specific mortality. Conclusions: Although they require further validation through larger studies, our findings suggest that the patterns of expression of PN in both compartments can allow for the development of IHC "signatures" that maintain a strong independent predictive value of both all causes and, namely, of cancer-specific mortality.openNuzzo, P.V.; Rubagotti, A.; Zinoli, L.; Salvi, S.; Boccardo, S.; Boccardo, F.Nuzzo, PIER VITALE; Rubagotti, Alessandra; Zinoli, Linda; Salvi, Sara; Boccardo, S.; Boccardo, F

    Ammonium formate-Pd/C as a new reducing system for 1,2,4-oxadiazoles. Synthesis of guanidine derivatives and reductive rearrangement to quinazolin-4-ones with potential anti-diabetic activity

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    1,2,4-Oxadiazole is a heterocycle with wide reactivity and many useful applications. The reactive O-N bond is usually reduced using molecular hydrogen to obtain amidine derivatives. NH4 CO2 H-Pd/C is here demonstrated as a new system for the O-N reduction, allowing us to obtain differently substituted acylamidine, acylguanidine and diacylguanidine derivatives. The proposed system is also effective for the achievement of a reductive rearrangement of 5-(2′-aminophenyl)-1,2,4-oxadiazoles into 1-alkylquinazolin-4(1H)-ones. The alkaloid glycosine was also obtained with this method. The obtained compounds were preliminarily tested for their biological activity in terms of their cytotoxicity, induced oxidative stress, α-glucosidase and DPP4 inhibition, showing potential application as anti-diabetics

    Comparative study of imiquimod 3.75% vs. photodynamic therapy for actinic keratosis of the scalp

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    Background/purpose: To assess efficacy, tolerability, adverse effects, recurrence, and aesthetic results of imiquimod 3.75% vs. photodynamic therapy with 5-aminolaevulinic acid (MAL-PDT) for actinic keratosis (AK). Methods: A small randomized, intraindividual right-left pilot study for AK treatment of multiple scalp lesions was performed. Patients were treated with imiquimod and subsequently MAL-PDT (on opposite sides of the scalp) 14 days apart. Study end points were evaluated with clinical and dermoscopic examinations at 1, 3, 6, and 12 months. Results: Nine male bald patients were enrolled. Imiquimod achieved a slightly higher overall clearance rate than MAP-PDT (68.1% vs 56.5%). According to AK degree of severity, clearance rates were greater for degree I and III with imiquimod (68.8%, 64.5% and 75% with imiquimod vs. 48%, 69.8%, and 66.7% for MAL-PDT, respectively). At 12 months, a slightly higher total recurrence rate was noted for imiquimod compared with MAL-PDT (9.9% vs. 8.6%); new lesions were 2 degree I for imiquimod and 4 degree I for MAL-PDT. For both treatments, pain was moderate/strong (even if MAL-PDT seems to be less tolerable) adverse effects are common and transient; aesthetic results excellent. Conclusion: Both imiquimod and MAL-PDT were effective in the reduction in the number of AK. In the long-term, both present a good effectiveness maintained over time with excellent aesthetic results. A combination or sequential therapy could optimize the management of the cancerization field

    A study of gas contaminants and interaction with materials in RPC closed loop systems

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    Resistive Plate Counters (RPC) detectors at the Large Hadron Collider (LHC) experiments use gas recirculation systems to cope with large gas mixture volumes and costs. In this paper a long-term systematic study about gas purifiers, gas contaminants and detector performance is discussed. The study aims at measuring the lifetime of purifiers with unused and used cartridge material along with contaminants release in the gas system. During the data-taking the response of several RPC double-gap detectors was monitored in order to characterize the correlation between dark currents, filter status and gas contaminants
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