423 research outputs found
Flexible body dynamic stability for high performance aircraft
Dynamic equations which include the effects of unsteady aerodynamic forces and a flexible body structure were developed for a free flying high performance fighter aircraft. The linear and angular deformations are assumed to be small in the body reference frame, allowing the equations to be linearized in the deformation variables. Equations for total body dynamics and flexible body dynamics are formulated using the hybrid coordinate method and integrated in a state space format. A detailed finite element model of a generic high performance fighter aircraft is used to generate the mass and stiffness matrices. Unsteady aerodynamics are represented by a rational function approximation of the doublet lattice matrices. The equations simplify for the case of constant angular rate of the body reference frame, allowing the effect of roll rate to be studied by computing the eigenvalues of the system. It is found that the rigid body modes of the aircraft are greatly affected by introducing a constant roll rate, while the effect on the flexible modes is minimal for this configuration
Bismuth-Based Nano- and Microparticles in X-Ray Contrast, Radiation Therapy, and Radiation Shielding Applications
Bismuth has gained attention in preclinical research because of its ability to attenuate X-rays and high biocompatibility, which make it an excellent element for use in a biomedical agent or in radiation shielding. Developments in the synthesis of elemental bismuth nano- and microparticles, their X-radiation interactions, and their biological interactions will be reviewed in this chapter. The chapter will pay special focus to emerging medical applications of elemental bismuth nano- and microparticles, including the possibility of targeted molecular X-ray imaging, photo-thermal and X-radiation dose enhancing therapies for cancer treatment, and the construction of flexible radiation shielding materials and X-ray opaque devices
Collaboration to Support Rural Student Social-Emotional Needs
There is a growing emphasis in U.S. schools to focus on the social-emotional issues of rural students. Specifically, the effect of mental health issues on school success underscores the importance of collaboration between, and among, educators and specialized support personnel (SSP; e.g., school counselors). In rural areas, school counselors and school psychologists are positioned to assist students and their families to provide support within and surrounding the school environment. The purpose of this paper is to: (1) discuss students’ social-emotional needs and SSP-educator collaboration in the context of rural schools, and (2) to discuss promising and best practices in collaboration to address students’ social-emotional well-being
Aerobic Method for the Synthesis of Nearly Size-Monodisperse Bismuth Nanoparticles from a Redox Non-Innocent Precursor
Herein, we report an aerobic synthesis method to produce bismuth nanoparticles (Bi NPs) with average diameters in the range 40-80 nm using commercially available bismuth triiodide (BiI3) as starting material; the method uses only readily available chemicals and conventional laboratory equipment. Furthermore, size data from replicates of the synthesis under standard reaction conditions indicate that this method is highly reproducible in achieving Bi NP populations with low standard deviations in the mean diameters. We also investigated the mechanism of the reaction, which we determined results from the reduction of a soluble alkylammonium iodobismuthate precursor species formed in situ. Under appropriate concentration conditions of iodobismuthate anion, we demonstrate that burst nucleation of Bi NPs results from reduction of Bi3+ by the coordinated, redox non-innocent iodide ligands when a threshold temperature is exceeded. Finally, we demonstrate phase transfer and silica coating of the Bi NPs, which results in stable aqueous colloids with retention of size, morphology, and colloidal stability. The resultant, high atomic number, hydrophilic Bi NPs prepared using this synthesis method have potential for application in emerging X-ray contrast and X-ray therapeutic applications
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Evolution of some Los Alamos flux compression programs
When we were approached to give a general discussion of some aspects of the Los Alamos flux compression program, we decided to present historical backgrounds of a few topics that have some relevance to programs that we very much In the forefront of activities going on today. Of some thirty abstracts collected at Los Alamos for this conference, ten of them dealt with electromagnetic acceleration of materials, notably the compression of heavy liners, and five dealt with plasma compression. Both of these topics have been under investigation, off and on, from the time a formal flux compression program was organized at Los Alamos. We decided that a short overview of work done In these areas would be of some interest. Some of the work described below has been discussed in Laboratory reports that, while referenced and available, are not readily accessible. For completeness, some previously published, accessible work Is also discussed but much more briefly. Perhaps the most striking thing about the early work In these two areas is how primitive much of it was when compared to the far more sophisticated, related activities of today. Another feature of these programs, actually for most programs, Is their cyclic nature. Their relevance and/or funding seems to come land go. Eventually, many of the older programs come back into favor. Activities Involving the dense plasma focus (DPF), about which some discussions will be given later, furnish a classic example of this kind, coming Into and then out of periods of heightened interest. We devote the next two sections of this paper to a review of our work In magnetic acceleration of solids and of plasma compression. A final section gives a survey of our work In which thin foils are imploded to produce intense quantities of son x-rays. The authors are well aware of much excellent work done elsewhere In all of these topics, but partly because of space limitations, have confined this discussion to work done at Los Alamos
A brief description of geological and geophysical exploration of the Marysville geothermal area
Extensive geological and geophysical surveys were carried out at the Marysville geothermal area during 1973 and 1974. The area has high heat flow (up to microcalories per square centimeter-second, a negative gravity anomaly, high electrical resistivity, low seismic ground noise, and nearby microseismic activity. Significant magnetic and infrared anomalies are not associated with the geothermal area. The geothermal anomaly occupies the axial portion of a dome in Precambrian sedimentary rocks intruded by Cretaceous and Cenozoic granitic rocks. The results from a 2.4-km-deep test well indicate that the cause of the geothermal anomaly is hydrothermal convection in a Cenozoic intrusive. A maximum temperature of 95 C was measured at a depth of 500 m in the test well
Tris(1,10-Phenanthroline)Cobalt(II) Triiodide
The asymmetric unit of the title compound, [Co(C12H8N2)3](I3)2, contains one [Co(1,10-phenanthroline)3]2+ cation, half each of two centrosymmetric triiodide anions, and one complete triiodide anion. The title compound was synthesized solvothermally from Co(NO3)2, 1,10-phenanthroline, and SnI2, where the SnI2 reagent serves only as a source of I atoms
Tris(Ethylenediamine)Cobalt(III) Nonaiododibismuthate
The asymmetric unit of the title compound, [Co(C2H8N2)3][Bi2I9], crystallizes in the orthorhombic space group Cmc21. The asymmetric unit contains half of a [Co(en)3]3+ cation (en is ethylenediamine) and half of a [Bi2I9]3- anion. Both species are located on mirror planes, requiring the [Co(en)3]3+ cation to be present as a statistically disordered mixture of both enantiomeric forms. Crystals were grown solvothermally from an ethanol-water solvent mixture using rac-[Co(en)3]I3 and bismuth triiodide as starting materials. The compound is a rare example of a mixed-metal halobismuthate material
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