55,805 research outputs found

    Supersonic turbulent boundary-layer flows with mass injection through slots and/or porous walls

    Get PDF
    An implicit finite-difference method was used to solve the compressible boundary-layer equations, and to study the effects of mass transfer through porous plates, slots, and a combination of the two. The effects of the external pressure field were also included by using a global pressure interaction scheme. Two different eddy viscosity models were used for the slot and slot-porous combination cases: one was a two-layer model with inner and outer laws, and the other was a multi-layer model with as many as five separate layers. Results of the present method were compared with experimental data at a Mach number of 2.8. Comparisons of the skin friction reduction and Mach number profiles gave good to excellent agreement. Pressure interaction had little effect on the slot injection skin friction but increased the skin friction of the porous and slot-porous combination markedly

    Intensity-Correlation Spectroscopy

    Get PDF
    A survey is given of techniques for spectroscopic analysis using intensity fluctuations. Particular attention is given to counting times, the role of macroscopic sources and detectors, and the electronic constraints placed on the observations

    Universal Properties of Linear Magnetoresistance in Strongly Disordered Semiconductors

    Full text link
    Linear magnetoresistance occurs in semiconductors as a consequence of strong electrical disorder and is characterized by nonsaturating magnetoresistance that is proportional to the applied magnetic field. By investigating a disordered MnAs-GaAs composite material, it is found that the magnitude of the linear magnetoresistance (LMR) is numerically equal to the carrier mobility over a wide range and is independent of carrier density. This behavior is complementary to the Hall effect that is independent of the mobility and dependent on the carrier density. Moreover, the LMR appears to be insensitive to the details of the disorder and points to a universal explanation of classical LMR that can be applied to other material systems.Comment: Accepted by Phys. Rev. B (2010

    Hydrocarbons identified in extracts from estuarine water accommodated no. 2 fuel oil by gas chromatography-mass spectrometry

    Get PDF
    Results are presented on a computerized gas chromatograph-mass spectrometer analysis of methylene chloride and n-heptane extracts of a No. 2 fuel oil accommodated estuarine water sample. The analytical method is briefly described, and the limitations on the identifications are categorized. Some attempt was made to determine major and trace constituents in the water accommodate. Altogether 66 hydrocarbon compounds were identified specifically, and 75 compounds were partially identified. Seven compounds could be recognized as major constituents of the water accommodated oil and ten were present only as traces. The aromatic compounds found were alkyl benzenes, naphthalene, tetralin, indane, biphenyl, fluorene, anthracene, and some of their alkyl substituted isomers in the range of carbon numbers C7 to C15. Four n-alkanes, C10 to C13, were found along with four other assorted hydrocarbons

    Electrolysis of simulated lunar melts

    Get PDF
    Electrolysis of molten lunar soil or rock is examined as an attractive means of wresting useful raw materials from lunar rocks. It requires only hat to melt the soil or rock and electricity to electrolyze it, and both can be developed from solar power. The conductivities of the simple silicate diopside, Mg CaSi2O6 were measured. Iron oxide was added to determine the effect on conductivity. The iron brought about substantial electronic conduction. The conductivities of simulated lunar lavas were measured. The simulated basalt had an AC conductivity nearly a fctor of two higher than that of diopside, reflecting the basalt's slightly higher total concentration of the 2+ ions Ca, Mg, and Fe that are the dominant charge carriers. Electrolysis was shown to be about 30% efficient for the basalt composition

    Frobenius theorem and invariants for Hamiltonian systems

    Full text link
    We apply Frobenius integrability theorem in the search of invariants for one-dimensional Hamiltonian systems with a time-dependent potential. We obtain several classes of potential functions for which Frobenius theorem assures the existence of a two-dimensional foliation to which the motion is constrained. In particular, we derive a new infinite class of potentials for which the motion is assurately restricted to a two-dimensional foliation. In some cases, Frobenius theorem allows the explicit construction of an associated invariant. It is proven the inverse result that, if an invariant is known, then it always can be furnished by Frobenius theorem

    Three-dimensional cell to tissue assembly process

    Get PDF
    The present invention relates a 3-dimensional cell to tissue and maintenance process, more particularly to methods of culturing cells in a culture environment, either in space or in a gravity field, with minimum fluid shear stress, freedom for 3-dimensional spatial orientation of the suspended particles and localization of particles with differing or similar sedimentation properties in a similar spatial region

    Asylum, immigration restrictions and exploitation: hyper-precarity as a lens for understanding and tackling forced labour

    Get PDF
    The topic of forced labour is receiving a growing amount of political and policy attention across the globe. This paper makes two clear contributions to emerging debates. First, we focus on a group who are seldom explicitly considered in forced labour debates; forced migrants who interact with the asylum system. We build an argument of the production of susceptibility to forced labour through the UK’s asylum system, discussing the roles of compromised socio-legal status resulting from restrictive immigration policy, neoliberal labour market characteristics and migrants’ own trajectories. Second, we argue that forced labour needs to be understood as part of, and an outcome of, widespread normalised precarious work. Precarity is a concept used to describe the rise of insecure, casualised and sub-contracted work and is useful in explaining labour market processes that are conducive to the production of forced labour. Using precarity as a lens to examine forced labour encourages the recognition of extreme forms of exploitation as part of a wider picture of systematic exploitation of migrants in the labour market. To understand the reasons why forced migrants might be drawn into severe labour exploitation in the UK, we introduce the concept of hyper-precarity to explain how multidimensional insecurities contribute to forced labour experiences, particularly among forced migrants in the Global North. Viewing forced labour as connected to precarity also suggests that avenues and tools for tackling severe labour exploitation need to form part of the wider struggle for migrant labour rights

    The Windrush Compensation Scheme: Unmet Need For Legal Advice

    Get PDF
    The aim of this research was to obtain a better understanding of the unmet need for legal advice amongst those who have been affected by the Windrush scandal, as well as other factors influencing the success of claims. The research is also intended to inform the development of the Windrush Justice Clinic (WJC) and to assess how best the Clinic can deliver support to those who most need it. The research found that: a. the WCS application process is too complex for claimants to complete alone and the limited support provided by the Home Office is insufficient; b. legal advice and support is necessary for claimants to prepare their applications, provide necessary evidence and pursue reviews if appropriate; c. other than the WJC and its partner organisations, there are very few sources of totally free and easily accessible legal advice for WCS claimants in the UK; d. this preliminary research has been unable to quantify the exact number of people with an unmet need. However, available statistics suggest that it is highly likely that there are significant numbers of people who have been affected by the Windrush Scandal who would benefit from from legal advice to make a claim under the WCS, seek a review of an existing offer, or to ensure payment of an award that has been offered
    • …
    corecore