45,609 research outputs found
Interplanetary mission design handbook. Volume 1, part 1: Earth to Venus ballistic mission opportunities, 1991-2005
Graphical data necessary for the preliminary design of ballistic missions to Venus is presented. Contours of launch energy requirements, as well as many other launch and arrival parameters, are presented in launch data/arrival date space for all launch opportunities from 1991 through 2005. An extensive text is included which explains mission design methods, from launch window development to Venus probe and orbiter arrival design, utilizing the graphical data in this volume as well as numerous equations relating various parameters
Multi-aspect, robust, and memory exclusive guest os fingerprinting
Precise fingerprinting of an operating system (OS) is critical to many security and forensics applications in the cloud, such as virtual machine (VM) introspection, penetration testing, guest OS administration, kernel dump analysis, and memory forensics. The existing OS fingerprinting techniques primarily inspect network packets or CPU states, and they all fall short in precision and usability. As the physical memory of a VM always exists in all these applications, in this article, we present OS-Sommelier+, a multi-aspect, memory exclusive approach for precise and robust guest OS fingerprinting in the cloud. It works as follows: given a physical memory dump of a guest OS, OS-Sommelier+ first uses a code hash based approach from kernel code aspect to determine the guest OS version. If code hash approach fails, OS-Sommelier+ then uses a kernel data signature based approach from kernel data aspect to determine the version. We have implemented a prototype system, and tested it with a number of Linux kernels. Our evaluation results show that the code hash approach is faster but can only fingerprint the known kernels, and data signature approach complements the code signature approach and can fingerprint even unknown kernels
Control of crystal polymorph in microfluidics using molluscan 28 kDa Ca2+-binding protein
Biominerals produced by biological systems in physiologically relevant environments possess extraordinary properties that are often difficult to replicate under laboratory conditions. Understanding the mechanism that underlies the process of biomineralisation can lead to novel strategies in the development of advanced materials. Using microfluidics, we have demonstrated for the first time, that an extrapallial (EP) 28 kDa protein, located in the extrapallial compartment between mantle and shell of Mytilus edulis, can influence, at both micro- and nanoscopic levels, the morphology, structure and polymorph that is laid down in the shell ultrastructure. Crucially, this influence is predominantly dependent on the existence of an EP protein concentration gradient and its consecutive interaction with Ca2+ ions. Novel lemon-shaped hollow vaterite structures with a clearly defined nanogranular assembly occur only where particular EP protein and Ca2+ gradients co-exist. Computational fluid dynamics enabled the progress of the reaction to be mapped and the influence of concentration gradients across the device to be calculated. Importantly, these findings could not have been observed using conventional bulk mixing methods. Our findings not only provide direct experimental evidence of the potential influence of EP proteins in crystal formation, but also offer a new biomimetic strategy to develop functional biomaterials for applications such as encapsulation and drug delivery
Airflow in a Multiscale Subject-Specific Breathing Human Lung Model
The airflow in a subject-specific breathing human lung is simulated with a
multiscale computational fluid dynamics (CFD) lung model. The three-dimensional
(3D) airway geometry beginning from the mouth to about 7 generations of airways
is reconstructed from the multi-detector row computed tomography (MDCT) image
at the total lung capacity (TLC). Along with the segmented lobe surfaces, we
can build an anatomically-consistent one-dimensional (1D) airway tree spanning
over more than 20 generations down to the terminal bronchioles, which is
specific to the CT resolved airways and lobes (J Biomech 43(11): 2159-2163,
2010). We then register two lung images at TLC and the functional residual
capacity (FRC) to specify subject-specific CFD flow boundary conditions and
deform the airway surface mesh for a breathing lung simulation (J Comput Phys
244:168-192, 2013). The 1D airway tree bridges the 3D CT-resolved airways and
the registration-derived regional ventilation in the lung parenchyma, thus a
multiscale model. Large eddy simulation (LES) is applied to simulate airflow in
a breathing lung (Phys Fluids 21:101901, 2009). In this fluid dynamics video,
we present the distributions of velocity, pressure, vortical structure, and
wall shear stress in a breathing lung model of a normal human subject with a
tidal volume of 500 ml and a period of 4.8 s. On exhalation, air streams from
child branches merge in the parent branch, inducing oscillatory jets and
elongated vortical tubes. On inhalation, the glottal constriction induces
turbulent laryngeal jet. The sites where high wall shear stress tends to occur
on the airway surface are identified for future investigation of
mechanotransduction.Comment: This submission is part of the APS DFD Gallery of Fluid Motio
Wilson ratio of Fermi gases in one dimension
We calculate the Wilson ratio of the one-dimensional Fermi gas with spin
imbalance. The Wilson ratio of attractively interacting fermions is solely
determined by the density stiffness and sound velocity of pairs and of excess
fermions for the two-component Tomonaga-Luttinger liquid (TLL) phase. The ratio
exhibits anomalous enhancement at the two critical points due to the sudden
change in the density of states. Despite a breakdown of the quasiparticle
description in one dimension, two important features of the Fermi liquid are
retained, namely the specific heat is linearly proportional to temperature
whereas the susceptibility is independent of temperature. In contrast to the
phenomenological TLL parameter, the Wilson ratio provides a powerful parameter
for testing universal quantum liquids of interacting fermions in one, two and
three dimensions.Comment: 5+2 pages, 4+1 figures, Eq. (4) is proved, figures were refine
Institutional changes of social sector: experience of the United States and Japan for the development of China's elderly education system
As China enters the aging society, more and more attention has been paid to the education for the aged. The developed countries such as the United States, Japan that entered the aging society relatively early, in the elderly education have accumulated rich experience. By learning from their experience, we can better develop education for the aged and promote the development of human resources for the aged
Preliminary design and optimization of a G-band extended interaction oscillator based on a pseudospark-sourced electron beam
The design and simulation of a G-band extended interaction oscillator (EIO) driven by a pseudospark-sourced electron beam is presented. The characteristic of the EIO and the pseudospark-based electron beam were studied to enhance the performance of the newly proposed device. The beam-wave interaction of the EIO can be optimized by choosing a suitable pseudospark discharging voltage and by widening the operating voltage region of the EIO circuit. Simulation results show that a peak power of over 240 W can be achieved at G-band using a pseudospark discharge voltage of 41 kV
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