Compressible flow structures interaction with a two-dimensional ejector: a cold-flow study

An experimental study has been conducted to examine the interaction of compressible flow structures such as shocks and vortices with a two-dimensional ejector geometry using a shock-tube facility. Three diaphragm pressure ratios ofP4 =P1 = 4, 8, and 12 have been employed, whereP4 is the driver gas pressure andP1 is the pressure within the driven compartment of the shock tube. These lead to incident shock Mach numbers of Ms = 1:34, 1.54, and 1.66, respectively. The length of the driver section of the shock tube was 700 mm. Air was used for both the driver and driven gases. High-speed shadowgraphy was employed to visualize the induced flowfield. Pressure measurements were taken at different locations along the test section to study theflow quantitatively. The induced flow is unsteady and dependent on the degree of compressibility of the initial shock wave generated by the rupture of the diaphragm

Novel ionic liquid [Et3N-SO3H][MeSO3]: Synthesis, characterization and catalytic performance for the synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes

The main aim of this work is introducing a novel protic acidic ionic-liquid catalyst for organic synthesis. Thus, N,N-diethyl-N-sulfoethanaminium methanesulfonate ([Et3N-SO3H][MeSO3]) was synthesized by the reaction of triethylamine with chlorosulfonic acid, and then with methanesulfonic acid. The structure of this novel protic acidic ionic liquid was identified by FT-IR, 1H NMR, 13C NMR and mass spectral data. Its catalytic activity was examined for the solvent-free reaction of 2-naphthol with arylaldehydes to provide 14-aryl-14H-dibenzo[a,j]xanthenes. [Et3N-SO3H][MeSO3] efficiently catalyzed the reaction, and the products were obtained in high to excellent yields and in short reaction times.               KEY WORDS: Protic acidic ionic liquid, N,N-Diethyl-N-sulfoethanaminium methanesulfonate ([Et3N-SO3H][MeSO3]), 2-Naphthol, Arylaldehyde, 14-Aryl-14H-dibenzo[a,j]xanthene Bull. Chem. Soc. Ethiop. 2019, 33(1), 69-76DOI: https://dx.doi.org/10.4314/bcse.v33i1.

Spin-squeezing and Dicke state preparation by heterodyne measurement

We investigate the quantum non-demolition (QND) measurement of an atomic population based on a heterodyne detection and show that the induced back-action allows to prepare both spin-squeezed and Dicke states. We use a wavevector formalism to describe the stochastic process of the measurement and the associated atomic evolution. Analytical formulas of the atomic distribution momenta are derived in the weak coupling regime both for short and long time behavior, and they are in good agreement with those obtained by a Monte-Carlo simulation. The experimental implementation of the proposed heterodyne detection scheme is discussed. The role played in the squeezing process by the spontaneous emission is considered

Strong-field approximation for Coulomb explosion of H_2^+ by short intense laser pulses

We present a simple quantum mechanical model to describe Coulomb explosion of H$_2^+$ by short, intense, infrared laser pulses. The model is based on the length gauge version of the molecular strong-field approximation and is valid for pulses shorter than 50 fs where the process of dissociation prior to ionization is negligible. The results are compared with recent experimental results for the proton energy spectrum [I. Ben-Itzhak et al., Phys. Rev. Lett. 95, 073002 (2005), B. D. Esry et al., Phys. Rev. Lett. 97, 013003 (2006)]. The predictions of the model reproduce the profile of the spectrum although the peak energy is slightly lower than the observations. For comparison, we also present results obtained by two different tunneling models for this process.Comment: 8 pages, 4 figure

Behavior analysis of factors affecting safety management to reduce incidents in the pelletizing industry using the system dynamics approach

The purpose of this study was to analyze the behavior of effective factors on safety management to reduce incidents in the pelletizing industry using the system dynamics approach. Risk assessment for the Sechahon pelletizing plant was performed using the FMEA method. A total of 625 risks were identified in this complex of which 286 are high risk RPNs and need to be scrutinized. These risks were categorized according to their nature and consequences in five physical categories, exposure to dust, ergonomics, emergencies and psychosocial risks, so that they can be reviewed in detail. The results showed that decreasing the number of incidents in the risk reduction scenario would reduce the incidence earlier, and is initially more than other policies. The scenario of risk reduction is the best scenario in the short term. The technology improvement scenario shows an incremental growth trend, but the scenario of the current situation can better decrease the number of incidents. The human resource management and safety management scenario will initially be on an upward trend and will continue to decline. The human resource management and safety management scenario is a good way to reduce disasters in the long run. Keywords: safety management, system dynamics, incident reduction, pelletizing industry. DOI: 10.7176/IEL/10-1-06 Publication date: February 29th 202

Exciton coherence lifetimes from electronic structure

We model the coherent energy transfer of an electronic excitation within covalently linked aromatic homodimers from first-principles, to answer whether the usual models of the bath calculated via detailed electronic structure calculations can reproduce the key dynamics. For these systems the timescales of coherent transport are experimentally known from time-dependent polarization anisotropy measurements, and so we can directly assess the whether current techniques might be predictive for this phenomenon. Two choices of electronic basis states are investigated, and their relative merits discussed regarding the predictions of the perturbative model. The coupling of the electronic degrees of freedom to the nuclear degrees of freedom is calculated rather than assumed, and the fluorescence anisotropy decay is directly reproduced. Surprisingly we find that although TDDFT absolute energies are routinely in error by orders of magnitude more than the coupling energy, the coherent transport properties of these dimers can be semi-quantitatively reproduced from first-principles. The directions which must be pursued to yield predictive and reliable prediction of coherent transport are suggested.Comment: 22 pages, 7 figure