Prediction of jet engine parameters for control design using genetic programming

The simulation of a jet engine behavior is widely used in many different aspects of the engine development and maintenance. Achieving high quality jet engine control systems requires the iterative use of these simulations to virtually test the performance of the engine avoiding any possible damage on the real engine. Jet engine simulations involve the use of mathematical models which are complex and may not always be available. This paper introduces an approach based on Genetic Programming (GP) to model different parameters of a small engine for control design such as the Exhaust Gas Temperature (EGT). The GP approach has no knowledge of the characteristics of the engine. Instead, the model is found by the evolution of models based on past measurements of parameters such as the pump voltage. Once the model is obtained, it is used to predict the behaviour of the jet engine one step ahead. The proposed approach is successfully applied for the simulation of a Behotec j66 jet engine and the results are presented

Sensitivity of nucleon-nucleus scattering to the off-shell behavior of on-shell equivalent NN potentials

The sensitivity of nucleon-nucleus elastic scattering to the off-shell behavior of realistic nucleon-nucleon interactions is investigated when on-shell equivalent nucleon-nucleon potentials are used. The study is based on applications of the full-folding optical model potential for an explicit treatment of the off-shell behavior of the nucleon-nucleon effective interaction. Applications were made at beam energies between 40 and 500 MeV for proton scattering from 40Ca and 208Pb. We use the momentum-dependent Paris potential and its local on-shell equivalent as obtained with the Gelfand-Levitan and Marchenko inversion formalism for the two nucleon Schroedinger equation. Full-folding calculations for nucleon-nucleus scattering show small fluctuations in the corresponding observables. This implies that off-shell features of the NN interaction cannot be unambiguously identified with these processes. Inversion potentials were also constructed directly from NN phase-shift data (SM94) in the 0-1.3 GeV energy range. Their use in proton-nucleus scattering above 200 MeV provide a superior description of the observables relative to those obtained from current realistic NN potentials. Limitations and scope of our findings are presented and discussed.Comment: 17 pages tightened REVTeX, 8 .ps figures, submitted to Phys. Rev.

Speaking as (Significant) Othered

Amy and Christina sat together in their living room. Amy held her phone, scrolling through notes she had typed a few minutes before their meeting. Christina’s laptop lay open in front of her. “How do we start this?” Amy asks. “Do we need an abstract?” Christina smirks, “I don’t know if we need it right now. Even if we do, I never start by writing the abstract.” “Then how do we start?” Amy asks again, anxiously. “I think we can begin with what we bring to the table for this conversation about queer autoethnography: We are a queer couple in academia who often write duo/autoethnographies. It’s our chance to conceptualize how we view queer duo/autoethnography.” “Do you think our relationship is what makes our duo/autoethnography queer? Or is it us creating a co-constructed narrative that’s hard to identify where you end and I begin?” “I can see that. Before we fully dive into how we conceive queer duo/ autoethnography, how do you see queer autoethnography functioning?” “At the intersection of autoethnography and queer theory, ‘just stories’ are transformed and transformative as insurrectionary acts that offer revolt through juxtaposition.1 Queering autoethnography interrogates the idea that narratives not only become stories upon the body, but also storied upon various theoretical frameworks that suggest possible lenses for decoding the author/s’ experiences. Readers are simultaneously offered insight into the residuals of the positionality of the scholar. It becomes an issue of ‘what is being read?’ in conjunction with ‘what is supposed to be read?’

Barriers and Solutions to Advance Care Planning among Homeless-Experienced Older Adults.

Background/Objectives: Older homeless-experienced adults have low rates of advance care planning (ACP) engagement despite high rates of morbidity and mortality. To inform intervention development, we examined potential barriers and solutions to ACP engagement. Design: Cross-sectional qualitative study. Setting: We recruited adults who were homeless in the prior three years and ≥50 years of age in the San Francisco Bay Area, and recruited clinical stakeholders from a national meeting of homeless providers. We analyzed qualitative data using thematic analysis. Measurements: We conducted semistructured interviews with homeless-experienced older adults (n = 20) and focus groups with clinical stakeholders (n = 24) about perceived barriers and solutions to ACP engagement. Results: Participants considered ACP important, reflecting on deaths of people in their networks who had died. Participant-identified barriers to ACP included poor ACP knowledge, lack of familial ties and social isolation, competing priorities, avoidance and lack of readiness, fatalism and mistrust, and lack of ACP training for clinical and nonclinical staff. They identified solutions that included framing ACP as a way to provide meaning and assert choice, providing easy-to-read written documents focused on the populations' unique needs, tailoring content and delivery, initiating ACP in nonclinical settings, such as permanent supportive housing, and providing incentives. Conclusions: Both older homeless-experienced adults and clinical stakeholders believe that ACP is important, but acknowledge multiple barriers that impede engagement. By focusing on potential solutions, including capitalizing on opportunities outside of health care settings, focusing on the period after housing, and tailoring content, there are opportunities to improve ACP uptake

Detection of delta Scuti-like pulsation in H254, a pre-main sequence F-type star in IC 348

We present time series observations of intermediate mass PMS stars belonging to the young star cluster IC 348. The new data reveal that a young member of the cluster, H254, undergoes periodic light variations with delta Scuti-like characteristics. This occurrence provides an unambiguous evidence confirming the prediction that intermediate-mass pre-main sequence (PMS) stars should experience this transient instability during their approach to the main-sequence. On the basis of the measured frequency f=7.406 c/d, we are able to constrain the intrinsic stellar parameters of H254 by means of linear, non adiabatic, radial pulsation models. The range of the resulting luminosity and effective temperature permitted by the models is narrower than the observational values. In particular, the pulsation analysis allows to derive an independent estimate of the distance to IC 348 of about 320 pc. Further observations could either confirm the monoperiodic nature of H254 or reveal the presence of other frequencies.Comment: 7 pages, including 7 postscript figures, accepted for publication on A&

Functional medium-dependence of the nonrelativistic optical model potential

By examining the structure in momentum and coordinate space of a two-body interaction spherically symmetric in its local coordinate, we demonstrate that it can be disentangled into two distinctive contributions. One of them is a medium-independent and momentum-conserving term, whereas the other is functionally --and exclusively-- proportional to the radial derivative of the reduced matrix element. As example, this exact result was applied to the unabridged optical potential in momentum space, leading to an explicit separation between the medium-free and medium-dependent contributions. The latter does not depend on the strength of the reduced effective interaction but only on its variations with respect to the density. The modulation of radial derivatives of the density enhances the effect in the surface and suppresses it in the saturated volume. The generality of this result may prove to be useful for the study of surface-sensitive phenomena.Comment: 11 pages, 5 figures, submitted to Phys. Rev.

Coupled Al/Si and O/N order/disorder in BaYb[Si4–xAlxOxN7–x]sialon

The fractions of aluminium, [Al]/[Al + Si], and oxygen, [O]/[O + N], in crystallographically distinct sites of BaYb[Si4–xAlxOxN7–x] oxonitridoaluminosilicate (space group P63mc, No. 186) were refined based on the results of neutron powder diffraction for a synthetic sample with the composition of x = 2.2(2) and simulated as functions of temperature for the compositions x = 2 and x = 2.3 using a combination of static lattice energy calculations (SLEC) and Monte Carlo simulations. The SLEC calcu lations have been performed on a set of 800 structures differing in the distribution of Al/Si and O/N within the 2 × 2 × 2 supercell containing 36 formula units of BaYb[Si4–xAlxOxN7–x]. The SLEC were based on a transferable set of empirical interatomic potentials developed within the present study. The static lattice energies of these structures have been expanded in the basis set of pair-wise ordering energies and on-site chemical potentials. The ordering energies and the chemical potentials have been used to calculate the configuration energies of the oxonitridoaluminosilicates (so-called sialons) using a Monte Carlo algorithm. The simulations suggest that Al and O are distributed unevenly over two non-equivalent T(Si/Al) and three L(N/O) sites, respectively, and the distribution shows strong dependence both on the temperature and the composition. Both simulated samples exhibit order/disorder transitions in the temperature range 500–1000 K to phases with partial long-range order below these temperatures. Above the transition temperatures the Si/Al and N/O distributions are affected by short-range ordering. The predicted site occupancies are in a qualitative agreement with the neutron diffraction results

Variable stars in the open cluster NGC 6791 and its surrounding field

Aims: This work presents a high--precision variability survey in the field of the old, super metal-rich open cluster NGC 6791. Methods: The data sample consists of more than 75,000 high-precision CCD time series measurements in the V band obtained mainly at the Canada-France-Hawaii Telescope, with additional data from S. Pedro Martir and Loiano observatories, over a time span of ten nights. The field covers an area of 42x28 arcmin^2. Results: We have discovered 260 new variables and re-determined periods and amplitudes of 70 known variable stars. By means of a photometric evaluation of the membership in NGC 6791, and a preliminary membership based on the proper motions, we give a full description of the variable content of the cluster and surrounding field in the range 16<V<23.5. Accurate periods can be given for the variables with P<4.0 d, while for ones with longer periods the limited time-baseline hampered precise determinations. We categorized the entire sample as follows: 6 pulsating, 3 irregular, 3 cataclysmic, 89 rotational variables and 61 eclipsing systems; moreover, we detected 168 candidate variables for which we cannot give a variability class since their periods are much longer than our time baseline. Conclusions: On the basis of photometric considerations, and of the positions of the stars with respect to the center of the cluster, we inferred that 11 new variable stars are likely members of the cluster, for 22 stars the membership is doubtful and 137 are likely non-members. We also detected an outburst of about 3 mag in the light curve of a very faint blue star belonging to the cluster and we suggest that this star could be a new U Gem (dwarf nova) cataclysmic variable.Comment: 24 pages, 19 Figures, A&A accepte

Concentration of trace elements in raw milk from cows in the southeast of Córdoba province, Argentina

International audienceAbstractIn recent years, trace elements in cow milk have been considered good bioindicators of pollution in the agricultural environment. The aim of the study was to analyze the correlation between trace element content in livestock drinking water and cow milk from dairy farms located in the southeast of Córdoba province, Argentina. Groundwater is the main source of livestock drinking water. According to the results, trace elements were grouped in three categories: (a) those that were in high concentration in phreatic water and in low concentration in deep wells (As, V); (b) those which showed the opposite trend (Cu, Fe, Mn, Zn); and (c) those that were in very low concentrations in all water samples (Cd, Cr, Ni, Pb, and Se). In elements from group (a), a positive correlation between As content in water and in milk was observed. For elements included in group (b), it was observed a higher concentration in milk samples from farms that use deep wells, related with their higher concentrations in water. Cr, Ni, Pb, and Se milk contents are within the ranges reported in other areas. Soil and forage trace element content may contribute to their presence in milk. Since information about transference of trace elements from environmental matrices to milk is very scarce, at national and international levels, further studies are necessary, including speciation in milk and dairy products, to guarantee food safety