Modeling and Analysis of High Energy Laser Weapon System Performance in Varying Atmospheric Conditions

This thesis addresses two primary concerns relating to Directed Energy (DE) models and tests: need for more use of Design of Experiment (DOE) in structuring DE models and tests, and lack of modeling atmospheric variability in High Energy Laser (HEL) weapon system propagation models and tests. To address these concerns we use a DOE factorial design to capture main, interaction, and non-linear effects between modeled weapon design and environmental factors in a well defined simulated Air-to-Ground HEL engagement scenario. The scenario modeled considers a B1-B aircraft in the 2022 timeframe equipped with an HEL weapon, irradiating a ground target from 30K feet altitude. The High Energy Laser End-to-End Operational Simulation (HELEEOS), developed by the AFIT Center for Directed Energy (CDE), is used to model HEL propagation. Atmospheric variability is incorporated by using input from the Laser Environmental Effects Definition and Reference (LEEDER) model based on randomly selected daily meteorological data (METAR) for a specific geographic location. Results clearly indicate the practical significance of a number of HEL weapon design and environmental factors, to include a number of previously unidentified interactions and non-linear effects, on the final energy delivered to a target for our modeled scenario

Aspects on Feed Related Prophylactic Measures Aiming to Prevent Post Weaning Diarrhoea in Pigs

The ability of feed related measures to prevent or reduce post weaning diarrhoea (PWD) was examined in a split litter study including 30 pigs from 6 litters allotted into 5 groups. Four groups were exposed to 3 pathogenic strains of E. coli via the environment at weaning. Three of them were given zinc oxide, lactose+fibres or non-pathogenic strains of E. coli as probiotics. The challenged and the unchallenged control groups were given a standard creep feed. Diarrhoea was observed in all challenged groups but not among uninfected animals, and the incidence of diarrhoea was lower in the group given non-pathogenic E. coli compared to all other challenged groups. The severity of PWD also differed between litters. When corrected for mortality due to PWD, a decreased incidence of diarrhoea was also seen in the groups given zinc oxide or lactose+fibres. The dominating serotype of E. coli within faecal samples varied from day to day, also among diarrhoeic pigs, indicating that diarrhoea was not induced by one single serotype alone. The diversity of the faecal coliform populations decreased in all piglets during the first week post weaning, coinciding with an increased similarity between these populations among pigs in the challenged groups. This indicated an influence of the challenge strains, which ceased during the second week. The group given lactose+fibres was least affected with respect to these parameters. In conclusion feed related measures may alleviate symptoms of PWD

Activity test on young pheasants

International audienc

Physical Study by Surface Characterizations of Sarin Sensor on the Basis of Chemically Functionalized Silicon Nanoribbon Field Effect Transistor

Surface characterizations of an organophosphorus (OP) gas detector based on chemically functionalized silicon nanoribbon field-effect transistor (SiNR-FET) were performed by Kelvin Probe Force Microscopy (KPFM) and ToF-SIMS, and correlated with changes in the current-voltage characteristics of the devices. KPFM measurements on FETs allow (i) to investigate the contact potential difference (CPD) distribution of the polarized device as function of the gate voltage and the exposure to OP traces and, (ii) to analyze the CPD hysteresis associated to the presence of mobile ions on the surface. The CPD measured by KPFM on the silicon nanoribbon was corrected due to side capacitance effects in order to determine the real quantitative surface potential. Comparison with macroscopic Kelvin probe (KP) experiments on larger surfaces was carried out. These two approaches were quantitatively consistent. An important increase of the CPD values (between + 399 mV and + 302 mV) was observed after the OP sensor grafting, corresponding to a decrease of the work function, and a weaker variation after exposure to OP (between - 14 mV and - 61 mV) was measured. Molecular imaging by ToF-SIMS revealed OP presence after SiNR-FET exposure. The OP molecules were essentially localized on the Si-NR confirming effectiveness and selectivity of the OP sensor. A prototype was exposed to Sarin vapors and succeeded in the detection of low vapor concentrations (40 ppm).Comment: Paper and supporting information, J. Phys. Chem. C, 201

Grain boundary influence during short fatigue crack growth using a discrete dislocation technique

We have studied the effect of a grain boundary in front of a short edge crack on its propagation under cyclic loading conditions in bcc iron. The used model is a combination of a discrete dislocation formulation and a boundary element approach where the boundary is described by dislocation dipole elements, while the local plasticity is modeled by discrete dislocations. The grain boundary is considered impenetrable, but dislocations positioned in the vicinity of a grain boundary give raise to high stresses in neighboring grains which, eventually, results in nucleation of dislocations and a spread of the plastic zone into the next grain.Выполнены исследования влияния границ зерен у вершины короткой краевой трещи­ны, распространяющейся в ОЦК-железе в условиях циклического нагружения. При этом использовалась модель, сочетающая постановку задачи с точки зрения дискрет­ных дислокаций с гранично-элементным подходом, где граница описывается с помо­щью элементов диполя дислокации, а ло­кальная пластичность моделируется с помо­щью дискретных дислокаций. При этом постулируется, что граница зерна является непроницаемой, однако дислокации, находя­щиеся в окрестности границы зерна, генерируют высокие напряжения в соседних зер­нах, в результате чего имеет место зарож­дение дислокаций и распространение плас­тической зоны в следующее зерно

Connexin36 knockout mice display increased sensitivity to pentylenetetrazol-induced seizure-like behaviors

Large-scale synchronous firing of neurons during seizures is modulated by electrotonic coupling between neurons via gap junctions. To explore roles for connexin36 (Cx36) gap junctions in seizures, we examined the seizure threshold of connexin36 knockout (Cx36KO) mice using a pentylenetetrazol (PTZ) model

A comparison of algorithms for the construction of SZ cluster catalogues

J.-B. Melin et al.We evaluate the construction methodology of an all-sky catalogue of galaxy clusters detected through the Sunyaev-Zel'dovich (SZ) effect. We perform an extensive comparison of twelve algorithms applied to the same detailed simulations of the millimeter and submillimeter sky based on a Planck-like case. We present the results of this >SZ Challenge> in terms of catalogue completeness, purity, astrometric and photometric reconstruction. Our results provide a comparison of a representative sample of SZ detection algorithms and highlight important issues in their application. In our study case, we show that the exact expected number of clusters remains uncertain (about a thousand cluster candidates at |b| > 20 deg with 90% purity) and that it depends on the SZ model and on the detailed sky simulations, and on algorithmic implementation of the detection methods. We also estimate the astrometric precision of the cluster candidates which is found of the order of ~2 arcmin on average, and the photometric uncertainty of about 30%, depending on flux. © ESO, 2012.Peer Reviewe