Quarkonium physics at CMS

This article presents the determination of the J/ψ and ψ(2S) differential cross sections in proton-proton collisions at a centre-of-mass energy of 7TeV, as a function of transverse momentum and in several rapidity ranges, on the basis of the 2010 data collected by the CMS experiment. We also report the measurement of the differential production cross sections of Υ(1S), Υ(2S), and Υ(3S) as a function of transverse momentum and rapidity

Behavior of composite/metal aircraft structural elements and components under crash type loads: What are they telling us

Failure behavior results are presented from crash dynamics research using concepts of aircraft elements and substructure not necessarily designed or optimized for energy absorption or crash loading considerations. To achieve desired new designs which incorporate improved energy absorption capabilities often requires an understanding of how more conventional designs behave under crash loadings. Experimental and analytical data are presented which indicate some general trends in the failure behavior of a class of composite structures which include individual fuselage frames, skeleton subfloors with stringers and floor beams but without skin covering, and subfloors with skin added to the frame-stringer arrangement. Although the behavior is complex, a strong similarity in the static and dynamic failure behavior among these structures is illustrated through photographs of the experimental results and through analytical data of generic composite structural models. It is believed that the similarity in behavior is giving the designer and dynamists much information about what to expect in the crash behavior of these structures and can guide designs for improving the energy absorption and crash behavior of such structures

Analysis of the Space Shuttle Orbiter skin panels under simulated hydrodynamic loads

The Space Shuttle orbiter skin panels were analyzed under pressure loads simulating hydrodynamic loads to determine their capability to sustain a potential ditching and to determine pressures that typically would produce failures. Two Dynamic Crash Analysis of Structures (DYCAST) finite element models were used. One model was used to represent skin panels (bays) in the center body, while a second model was used to analyze a fuselage bay in the wing region of the orbiter. From an assessment of the DYCAST nonlinear computer results, it is concluded that the probability is extremely high that most, if not all, of the lower skin panels would rupture under ditching conditions. Extremely high pressure loads which are produced under hydrodynamic planning conditions far exceed the very low predicted failure pressures for the skin panels. Consequently, a ditching of the orbiter is not considered to have a high probability of success and should not be considered a means of emergency landing unless no other option exists

An overview of the crash dynamics failure behavior of metal and composite aircraft structures

An overview of failure behavior results is presented from some of the crash dynamics research conducted with concepts of aircraft elements and substructure not necessarily designed or optimized for energy absorption or crash loading considerations. Experimental and analytical data are presented that indicate some general trends in the failure behavior of a class of composite structures that includes fuselage panels, individual fuselage sections, fuselage frames, skeleton subfloors with stringers and floor beams without skin covering, and subfloors with skin added to the frame stringer structure. Although the behavior is complex, a strong similarity in the static/dynamic failure behavior among these structures is illustrated through photographs of the experimental results and through analytical data of generic composite structural models

A review of the analytical simulation of aircraft crash dynamics

A large number of full scale tests of general aviation aircraft, helicopters, and one unique air-to-ground controlled impact of a transport aircraft were performed. Additionally, research was also conducted on seat dynamic performance, load-limiting seats, load limiting subfloor designs, and emergency-locator-transmitters (ELTs). Computer programs were developed to provide designers with methods for predicting accelerations, velocities, and displacements of collapsing structure and for estimating the human response to crash loads. The results of full scale aircraft and component tests were used to verify and guide the development of analytical simulation tools and to demonstrate impact load attenuating concepts. Analytical simulation of metal and composite aircraft crash dynamics are addressed. Finite element models are examined to determine their degree of corroboration by experimental data and to reveal deficiencies requiring further development

Experimental investigation of dam-break usinglow cost laser sourcesand image processing techniques

Dambreak waves in a horizontal rectangular and smooth channel are measured using a number of low cost laser sources, fluorescent dies and Planar Laser Induced Fluorescence (PLIF). Even in such a simple configuration, the experiment are useful to investigate a number of factors such as: the initial wave formation process, the positive front propagation and the local velocity of the wave. The positive wave fronts and the shape of the waves are compared with analytically determined solution proposed by Ritter. The effect of the relative reservoir high on the wave maximum and shape is shown to reasonably agree with the Ritter solution. The results so obtained are discussed and allow a deeper insight into the mechanics of dam-break waves. The results are readily available for applications, and a significant modification regarding the initial flow conditions is described

Simulating the Impact Response of Composite Airframe Components

In 2010, NASA Langley Research Center obtained residual hardware from the US Army's Survivable Affordable Repairable Airframe Program (SARAP). The hardware consisted of a composite fuselage section that was representative of the center section of a Black Hawk helicopter. The section was fabricated by Sikorsky Aircraft Corporation and designated the Test Validation Article (TVA). The TVA was subjected to a vertical drop test in 2008 to evaluate a tilting roof concept to limit the intrusion of overhead mass items, such as the rotor transmission, into the fuselage cabin. As a result of the 2008 test, damage to the hardware was limited primarily to the roof. Consequently, when the post-test article was obtained in 2010, the roof area was removed and the remaining structure was cut into six different types of test specimens including: (1) tension and compression coupons for material property characterization, (2) I-beam sections, (3) T-sections, (4) cruciform sections, (5) a large subfloor section, and (6) a forward framed fuselage section. In 2011, NASA and Sikorsky entered into a cooperative research agreement to study the impact responses of composite airframe structures and to evaluate the capabilities of the explicit transient dynamic finite element code, LS-DYNA, to simulate these responses including damage initiation and progressive failure. Finite element models of the composite specimens were developed and impact simulations were performed. The properties of the composite material were represented using both a progressive in-plane damage model (Mat 54) and a continuum damage mechanics model (Mat 58) in LS-DYNA. This paper provides test-analysis comparisons of time history responses and the location and type of damage for representative I-beam, T-section, and cruciform section components

Development of a Continuum Damage Mechanics Material Model of a Graphite-Kevlar(Registered Trademark) Hybrid Fabric for Simulating the Impact Response of Energy Absorbing Kevlar(Registered Trademark) Hybrid Fabric for Simulating the Impact Response of Energy Absorbing

This paper describes the development of input properties for a continuum damage mechanics based material model, Mat 58, within LS-DYNA(Registered Trademark) to simulate the response of a graphite-Kevlar(Registered Trademark) hybrid plain weave fabric. A limited set of material characterization tests were performed on the hybrid graphite-Kevlar(Registered Trademark) fabric. Simple finite element models were executed in LS-DYNA(Registered Trademark) to simulate the material characterization tests and to verify the Mat 58 material model. Once verified, the Mat 58 model was used in finite element models of two composite energy absorbers: a conical-shaped design, designated the "conusoid," fabricated of four layers of hybrid graphite-Kevlar(Registered Trademark) fabric; and, a sinusoidal-shaped foam sandwich design, designated the "sinusoid," fabricated of the same hybrid fabric face sheets with a foam core. Dynamic crush tests were performed on components of the two energy absorbers, which were designed to limit average vertical accelerations to 25- to 40-g, to minimize peak crush loads, and to generate relatively long crush stroke values under dynamic loading conditions. Finite element models of the two energy absorbers utilized the Mat 58 model that had been verified through material characterization testing. Excellent predictions of the dynamic crushing response were obtained

Identification of Universally Applicable and Species-Specific Marker Peptides for Bacillus anthracis

Anthrax is a zoonotic infection caused by the bacterium Bacillus anthracis (BA). Specific identification of this pathogen often relies on targeting genes located on two extrachromosomal plasmids, which represent the major pathogenicity factors of BA. However, more recent findings show that these plasmids have also been found in other closely related Bacillus species. In this study, we investigated the possibility of identifying species-specific and universally applicable marker peptides for BA. For this purpose, we applied a high-resolution mass spectrometry-based approach for 42 BA isolates. Along with the genomic sequencing data and by developing a bioinformatics data evaluation pipeline, which uses a database containing most of the publicly available protein sequences worldwide (UniParc), we were able to identify eleven universal marker peptides unique to BA. These markers are located on the chromosome and therefore, might overcome known problems, such as observable loss of plasmids in environmental species, plasmid loss during cultivation in the lab, and the fact that the virulence plasmids are not necessarily a unique feature of BA. The identified chromosomally encoded markers in this study could extend the small panel of already existing chromosomal targets and along with targets for the virulence plasmids, may pave the way to an even more reliable identification of BA using genomics- as well as proteomics-based techniques

Simulating the Impact Response of Full-Scale Composite Airframe Structures

NASA Langley Research Center obtained a composite helicopter cabin structure in 2010 from the US Army's Survivable Affordable Repairable Airframe Program (SARAP) that was fabricated by Sikorsky Aircraft Corporation. The cabin had been subjected to a vertical drop test in 2008 to evaluate a tilting roof concept to limit the intrusion of overhead masses into the fuselage cabin. Damage to the cabin test article was limited primarily to the roof. Consequently, the roof area was removed and the remaining structure was cut into test specimens including a large subfloor section and a forward framed fuselage section. In 2011, NASA and Sikorsky entered into a cooperative research agreement to study the impact responses of composite airframe structures and to evaluate the capabilities of the explicit transient dynamic finite element code, LS-DYNA, to simulate these responses including damage initiation and progressive failure. Most of the test articles were manufactured of graphite unidirectional tape composite with a thermoplastic resin system. However, the framed fuselage section was constructed primarily of a plain weave graphite fabric material with a thermoset resin system. Test data were collected from accelerometers and full-field photogrammetry. The focus of this paper will be to document impact testing and simulation results for the longitudinal impact of the subfloor section and the vertical drop test of the forward framed fuselage section