Location of leaks in pipelines using parameter identification tools

This work proposes an approach to locate leaks by identifying the parameters of finite models associated with these fault events. The identification problem is attacked by using well-known identification methods such as the Prediction Error Method and extended Kalman filters. In addition, a frequency evaluation is realized to check the conditions for implementing any method which require an excitation condition.Comment: This paper has some error

On Chow Stability for algebraic curves

In the last decades there have been introduced different concepts of stability for projective varieties. In this paper we give a natural and intrinsic criterion of the Chow, and Hilbert, stability for complex irreducible smooth projective curves $C\subset \mathbb P ^n$. Namely, if the restriction $T\mathbb P_{|C} ^n$ of the tangent bundle of $\mathbb P ^n$ to $C$ is stable then $C\subset \mathbb P ^n$ is Chow stable, and hence Hilbert stable. We apply this criterion to describe a smooth open set of the irreducible component $Hilb^{P(t),s}_{{Ch}}$ of the Hilbert scheme of $\mathbb{P} ^n$ containing the generic smooth Chow-stable curve of genus $g$ and degree $d>g+n-\left\lfloor\frac{g}{n+1}\right\rfloor.$ Moreover, we describe the quotient stack of such curves. Similar results are obtained for the locus of Hilbert stable curves.Comment: Minor corrections and improvements to presentation. We add Theorem 4.

Exchange rate dynamics in crawling-band systems

In this note we show that an exchange rate crawling-band system can borrow a portion of those aspects of a target zone that lead to its stabilizing effects on the exchange rate, depending on the relationship between the crawl rate and the drift of the fundamentals process. If the crawl rate is sufficiently high (with respect to the drift), the crawling-band is similar to a free float regime. As the crawl rate decreases, the crawling-band system collapses to a standard target zone.crawling band

Primordial black hole production during preheating in a chaotic inflationary model

In this paper we review the production of primordial black holes (PBHs) during preheating after a chaotic inflationary model. All relevant equations of motion are solved numerically in a modified version of HLattice, and we then calculate the mass variance to determine structure formation during preheating. It is found that production of PBHs can be a generic result of the model, even though the results seem to be sensitive to the values of the smoothing scale. We consider a constraint for overproduction of PBHs that could uncover some stress between inflation-preheating models and observations.Comment: 6 pages, 5 figures. Prepared for the conference proceedings of the 9th Mexican School on Gravitation and Mathematical Physics : Cosmology for the XXI Century: Inflation, Dark Matter and Dark Energ

Performance evaluation of electrochemical concentration cell ozonesondes

Laboratory calibrations of more than a hundred electrochemical concentration cell (ECC) ozonesondes were determined relative to UV-photometry. The average intercept and slope, 0 plus or minus 5 nb and 0.96 plus or minus 0.06, respectively, indicate reasonable agreement with UV photometry, but with considerable variation from one ECC ozonesonde to another. The time required to reach 85% of the final reaction to a step-change in ozone concentration was found to average 51 seconds. Application of the individual calibrations to 20 sets of 1976 flight data reduced the average of the differences between ozonesonde and Dobson spectrophotometric measurements of total ozone from 3.9 to 1.3%. A similar treatment of a set of 10 1977 flight records improved the average ECC-Dobson agreement from -8.5 to -1.4%. Although systematic differences were reduced, no significant effect on the random variations was evident

Microaggressions and Psychological Functioning among High Achieving African-Americans: A Mixed-Methods Approach

Racial microaggressions and their influence on mental health were examined among African American doctoral students and graduates of doctoral programs. Using a mixed-methods approach, the current study first identified the types of microaggressions reported by African American participants (N = 97) and then investigated the mechanism by which these experiences influence mental health over time with a separate sample of African Americans (N = 107). The qualitative findings revealed three categories of microaggressions including Assumption of Criminality/Second-Class Citizen, Underestimation of Personal Ability, and Cultural/racial Isolation. The quantitative analyses found support for a moderated-mediational model by which Underestimation of Personal Ability was associated with greater perceived stress at one-year follow-up, which in turn was related to greater depressive symptoms. Active coping was found to moderate the racial microaggression-perceived stress link such that individuals who endorse active coping behaviors reported lower perceived stress. These findings are discussed in terms of practical and theoretical implications regarding the role of racial micro-aggressions in the lives of high-achieving African Americans and the mechanisms by which these experiences contribute to mental health problems