Propellant combustion phenomena during rapid depressurization Final report

Idealized combustion model in which exothermic or endothermic reactions are permitted at or very near solid-gas interface

A theoretical and experimental study of propellant combustion phenomena during rapid depressurization Final report

Modified solid propellant combustion model for steady state analyses of burning rate and flame temperatur

Misallocation, Access to Finance, and Public Credit: Firm-Level Evidence

Using a database of 23,000 firms in 45 economies, we test the quantitative importance of access to finance and access to public and private credit for the determination of misallocation. We first derive measures of factor market and size distortions, and then use these measures within a regression framework to test the significance of self-declared access-to-finance obstacles as well as the effect of access to a credit line issued by either a government-owned or private bank. We find that access-to-finance obstacles and private credit increase the dispersion of distortions. Public credit has a very small effect. For firms that do not face financial obstacles, public credit increases the dispersion of distortions; for firms that face financial obstacles, it slightly decreases dispersion. Public credit does not appear to compensate for the distortions that exist in private credit markets. Quantitatively, however, financial variables explain a very small part of the dispersion of factor market and size distortions

Global and regional effects of the photochemistry of CH_3O_2NO_2: evidence from ARCTAS

Using measurements from the NASA Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) experiment, we show that methyl peroxy nitrate (CH_3O_2NO_2) is present in concentrations of ~5–15 pptv in the springtime arctic upper troposphere. We investigate the regional and global effects of CH_3O_2NO_2 by including its chemistry in the GEOS-Chem 3-D global chemical transport model. We find that at temperatures below 240 K inclusion of CH_3O_2NO_2 chemistry results in decreases of up to ~20 % in NO_x, ~20 % in N_2O_5, ~5 % in HNO3, ~2 % in ozone, and increases in methyl hydrogen peroxide of up to ~14 %. Larger changes are observed in biomass burning plumes lofted to high altitude. Additionally, by sequestering NO_x at low temperatures, CH_3O_2NO_2 decreases the cycling of HO_2 to OH, resulting in a larger upper tropospheric HO_2 to OH ratio. These results may impact some estimates of lightning NO_x sources as well as help explain differences between models and measurements of upper tropospheric composition

Robust Estimation for Linear Panel Data Models

In different fields of applications including, but not limited to, behavioral, environmental, medical sciences and econometrics, the use of panel data regression models has become increasingly popular as a general framework for making meaningful statistical inferences. However, when the ordinary least squares (OLS) method is used to estimate the model parameters, presence of outliers may significantly alter the adequacy of such models by producing biased and inefficient estimates. In this work we propose a new, weighted likelihood based robust estimation procedure for linear panel data models with fixed and random effects. The finite sample performances of the proposed estimators have been illustrated through an extensive simulation study as well as with an application to blood pressure data set. Our thorough study demonstrates that the proposed estimators show significantly better performances over the traditional methods in the presence of outliers and produce competitive results to the OLS based estimates when no outliers are present in the data set

Simultaneous dynamic electrical and structural measurements of functional materials

A new materials characterization system developed at the XMaS beamline, located at the European Synchrotron Radiation Facility in France, is presented. We show that this new capability allows to measure the atomic structural evolution (crystallography) of piezoelectric materials whilst simultaneously measuring the overall strain characteristics and electrical response to dynamically (ac) applied external stimuli

Expectation-Oriented Analysis and Design

A key challenge for agent-oriented software engineering is to develop and implement open systems composed of interacting autonomous agents. On the one hand, there is a need for permitting autonomy in order to support desirable system properties such as decentralised control. On the other hand, there is a need for restricting autonomy in order to reduce undesirable system properties such as unpredictability. This paper introduces a novel analysis and design method for open agent-oriented software systems that aims at coming up to both of these two contrary aspects. The characteristics of this method, called EXPAND, are as follows: (i) it allows agents a maximum degree of autonomy and restricts autonomous behaviour only if necessary (ii) it uses systemlevel expectations as a key modelling abstraction and as the primary level of analysis and design; and (iii) it is sociologically grounded in Luhmann's systems theory. The application of EXPAND is illustrated in a "car-trading platform" case study

On the export of reactive nitrogen from Asia: NO\u3csub\u3ex\u3c/sub\u3e partitioning and effects on ozone

The partitioning of reactive nitrogen (NOy was measured over the remote North Pacific during spring 2006. Aircraft observations of NO, NO2, total peroxy nitrates (ΣPNs), total alkyl and multi-functional nitrates (ΣANs) and nitric acid (HNO3, made between 25° and 55° N, confirm a controlling role for peroxyacyl nitrates in NOx production in aged Asian outflow. ΣPNs account for more than 60% of NOy above 5 km, while thermal dissociation limits their contribution to less than 10% in the lower troposphere. Using simultaneous observations of NOx, ΣPNs, ΣANs, HNO3 and average wind speed, we calculate the flux of reactive nitrogen through the meridional plane of 150° W (between 20° and 55° N) to be 0.007 ± 0.002 Tg N day−1, which provides an upper limit of 23 ± 6.5% on the transport efficiency of NOy from East Asia. Observations of NOx, and HOx are used to constrain a 0-D photochemical box model for the calculation of net photochemical ozone production or tendency (Δ O3) as a function of aircraft altitude and NOx concentrations. The model analysis indicates that the photochemical environment of the lower troposphere (altitude \u3c 6 km) over the north Pacific is one of net O3 destruction, with an experimentally determined crossover point between net O3 destruction and net O3 production of 60 pptv NOx. Qualitative indicators of integrated net O3 production derived from simultaneous measurements of O3 and light alkanes (Parrish et al., 1992), also indicate that the north Pacific is, on average, a region of net O3 destruction

Observations of total peroxy nitrates and aldehydes: measurement interpretation and inference of OH radical concentrations

International audienceWe describe measurements of total peroxy nitrates (?PNs), NO2, O3 and several aldehydes at Granite Bay, California, during the Chemistry and Transport of the Sacramento Urban Plume-2001 (CATSUP 2001) campaign, from 19 July?16 September 2001. We observed a strong photochemically driven variation of ?PNs during the day with the median of 1.2 ppb at noon. Acetaldehyde, pentanal, hexanal and methacrolein had median abundances in the daytime of 1.2 ppb, 0.093 ppb, 0.14 ppb, and 0.27 ppb, respectively. We compare steady state and time dependent calculations of the dependence of ?PNs on aldehydes, OH, NO and NO2 showing that the steady state calculations are accurate to ±30% between 10:00 and 18:00 h. We use the steady state calculation to investigate the composition of ?PNs and the concentration of OH at Granite Bay. We find that PN molecules that have never been observed before make up an unreasonably large fraction of the ?PNs unless we assume that there exists a PAN source that is much larger than the acetaldehyde source. We calculate that OH at the site varied between 2 and 7×106 molecule cm?3 at noon during the 8 weeks of the experiment

The wage and employment consequences of ownership change

This paper provides a comparative examination of the consequences of leveraged buyouts (LBOs) and corporate takeovers on employment growth and wage growth. Employing both difference-in-differences combined with propensity score matching and the control function approach, we find evidence that (i) wages remain unchanged after either a private equity (PE)-backed or non-PE-backed LBO, (ii) wages remain unchanged after an unrelated takeover and (iii) related takeovers have negative employment consequences, possibly because of rationalisation. Our evidence does not find strong support for intervention in the market for corporate control on the grounds of protecting employees' welfare