Film/Adhesive Processing Module for Fiber-Placement Processing of Composites

An automated apparatus has been designed and constructed that enables the automated lay-up of composite structures incorporating films, foils, and adhesives during the automated fiber-placement process. This apparatus, denoted a film module, could be used to deposit materials in film or thin sheet form either simultaneously when laying down the fiber composite article or in an independent step

Resolution Effects in the Hybrid Strong/Weak Coupling Model

Within the context of a hybrid strong/weak coupling model of jet quenching, we study the consequences of the fact that the plasma produced in a heavy ion collision cannot resolve the substructure of a collimated parton shower propagating through it with arbitrarily fine spatial resolution. We introduce a screening length parameter, $L_{\rm res}$, proportional to the inverse of the local temperature in the plasma, estimating a range for the value of the proportionality constant via comparing weakly coupled QCD calculations and holographic calculations appropriate in strongly coupled plasma. We then modify the hybrid model so that when a parton in a jet shower splits, its two offspring are initially treated as unresolved, and are only treated as two separate partons losing energy independently after they are separated by a distance $L_{\rm res}$. This modification delays the quenching of partons with intermediate energy, resulting in the survival of more hadrons in the final state with $p_T$ in the several GeV range. We analyze the consequences of different choices for the value of the resolution length, $L_{\rm res}$, and demonstrate that introducing a nonzero $L_{\rm res}$ results in modifications to the jet shapes and jet fragmentations functions, as it makes it more probable for particles carrying a small fraction of the jet energy at larger angles from the jet axis to survive their passage through the quark-gluon plasma. These effects are, however, small in magnitude, something that we confirm via checking for effects on missing-$p_T$ observables.Comment: 32 pages, 7 figure

Multi-functional layered structure having structural and radiation shielding attributes

A cosmic and solar radiation shielding structure that also has structural attributes is comprised of three layers. The first layer is 30-42 percent by volume of ultra-high molecular weight (UHMW) polyethylene fibers, 18-30 percent by volume of graphite fibers, and a remaining percent by volume of an epoxy resin matrix. The second layer is approximately 68 percent by volume of UHMW polyethylene fibers and a remaining percent by volume of a polyethylene matrix. The third layer is a ceramic material

Truancy : its sociological implications

The term, truancy , is interpreted in various ways. Julia Richman, District Superintendent of the Public Schools of New York in 1909, said, The law in some states defines truancy as a failure to attend school, making no difference between the parents offense in keeping the child at home and the child\u27s offense in remaining away from school without the parent\u27s knowledge. It is this latter form which the school and the school alone must check. A. o. Neal, Superintendent of Schools, Franklin,Indiana, in the same year said, Some Juvenile courts in Indiana have held that the truancy law means not only that the parent shall send the child to school, but that the child shall come provided with proper equipment and decently clothed and clean

Numerical Modeling of Hydraulic Fracture Propagation and Comparison with Microseismic Data at a Field Site

A hydraulic fracturing site in Morgantown, West Virginia, USA was selected to be a research site for the Marcellus Shale Energy and Environment Laboratory (MSEEL) project which was funded by the U.S. Department of Energy (DOE). The overall objective of the MSEEL research project is to evaluate and improve technologies to enhance shale gas recovery with minimal impacts on the environment. The field site has two previously drilled wells and two newly drilled wells for extracting natural gas. A separate exploratory well (or “science well”) was also drilled and includes a geophone array to extract important seismic/microseismic event information, which can then be used to help determine hydraulic fracture geometries. The main objective of the current research work was to perform numerical modeling of all hydraulic fracturing operations at both of these newly drilled wells at the MSEEL site and perform model calibration based on a statistical methodology and available microseismic data. Available geologic, geomechanical, and treatment data was utilized to build the numerical model for all stages at both of these wells and comparisons were made with available microseismic data. There are 28 hydraulic fracture stages at one well and 30 stages at a second well. These 58 stages were individually numerically modeled and a statistical methodology and available microseismic data was utilized to calibrate the model. Results show a good match between estimates/measurements and model calculations of height, length, and surface pressure

Extent of Hydraulic Fractures in a Multilayered Geologic Media

In this report, the vertical extent of hydraulic fractures in a layered geological formation was investigated. In reality, the geology of the earth is heterogeneous, and therefore fracture growth will be significantly different. Fracture growth was simulated by using numerical models with relevant geomechanical, fluid flow and proppant transport properties. Results show the horizontal stress gradient plays an important role in fracture propagation. Lower horizontal stress contrasts between layers allow for greater fracture propagation in the vertical direction. Higher fluid viscosities tend to increase the fracture height and width, while decreasing the fracture length. Several other geomechanical properties such as the elastic modulus, fracture toughness, and leakoff coefficient have some influence on the vertical fracture growth. To account for the variability of properties, 300 realizations were considered by using a statistical sampling method. Most of the simulated fractures (about 50%) extended into the immediate overburden layers. Results from these cases show that the clearance depth was in the range from about 4300 feet to 7500 feet

Fabrication of Thermoplastic Composite Laminates Having Film Interleaves by Automated Fiber Placement

Experiments were carried out at the NASA Langley Research Center automated fiber placement facility to determine an optimal process for the fabrication of composite materials having polymer film interleafs. A series of experiments was conducted to determine an optimal process for the composite prior to investigation of a process to fabricate laminates with polymer films. The results of the composite tests indicated that a well-consolidated, void-free laminate could be attained. Preliminary interleaf processing trials were then conducted to establish some broad guidelines for film processing. The primary finding of these initial studies was that a two-stage process was necessary in order to process these materials adequately. A screening experiment was then performed to determine the relative influence of the process variables on the quality of the film interface as determined by the wedge peel test method. Parameters that were found to be of minor influence on specimen quality were subsequently held at fixed values enabling a more rapid determination of an optimal process. Optimization studies were then performed by varying the remaining parameters at three film melt processing rates. The resulting peel data were fitted with quadratic response surfaces. Additional specimens were fabricated at levels of high peel strength as predicted by the regression models in an attempt to gage the accuracy of the predicted response and to assess the repeatability of the process. The overall results indicate that quality laminates having film interleaves can be successfully and repeatably fabricated by automated fiber placement

A simultaneous understanding of jet and hadron suppression

In the context of the hybrid strong/weak coupling model for jet quenching, we perform a global fit to hadron and jet data in the most central bins both at RHIC and LHC. The qualitative and quantitative success of the analysis is attributed to the fact that the model correctly captures the fact that wider jets lose, on average, more energy than the narrower ones, to which high energy hadrons belong. We show how one can understand the relative jet and hadron suppression by analyzing the jet fragmentation functions, and also discuss the role of plasma finite resolution effects

Simultaneous description of hadron and jet suppression in heavy-ion collisions

We present a global fit to all data on the suppression of high-energy jets and high-energy hadrons in the most central heavy-ion collisions at the CERN Large Hadron Collider (LHC) for two different collision energies, within a hybrid strong-weak coupling quenching model. Even though the measured suppression factors for hadrons and jets differ significantly from one another and appear to asymptote to different values in the high-energy limit, we obtain a simultaneous description of all these data after constraining the value of a single model parameter. We use our model to investigate the origin of the difference between the observed suppression of jets and hadrons and relate it, quantitatively, to the observed modification of the jet fragmentation function in jets that have been modified by passage through the medium produced in heavy-ion collisions. In particular, the observed increase in the fraction of hard fragments in medium-modified jets, which indicates that jets with the fewest hardest fragments lose the least energy, corresponds quantitatively to the observed difference between the suppression of hadrons and jets. We argue that a harder fragmentation pattern for jets with a given energy after quenching is a generic feature of any mechanism for the interaction between jets and the medium that they traverse that yields a larger suppression for wider jets. We also compare the results of our global fit to LHC data to measurements of the suppression of high-energy hadrons in BNL Relativistic Heavy Ion Collider (RHIC) collisions, and find that with its parameter chosen to fit the LHC data, our model is inconsistent with the RHIC data at the 3σ level, suggesting that hard probes interact more strongly with the less hot quark-gluon plasma produced at RHIC