20,934 research outputs found
Hermetic-coaxial package design for microwave transistors
Semiconductor package has been developed for high power semiconductor devices that operate in the GHz-frequency range at several watts. Package includes stud, insulating ring, electrically conductive washer, insulating washer, braze ring, and cap. It is mechanically strong and can be used with variety of circuits
Transistor bonding pad configuration for uniform injection and low inductance
Modification of process for fabricating transistors, which comprises a metallization-pattern design for emitter and base areas together with a double bonding configuration for each emitter and base-bonding lead, improves uniformity of carrier injection in transistors and of reducing lead inductances at base-emitter terminals
The Role of ERISA Preemption in Health Reform: Opportunities and Limits
The Employee Retirement Income Security Act (ERISA) is a federal law regulating the administration of private employer-sponsored benefits including health benefits (i.e., health insurance offered by an employer). In general, since the federal government has exercised its authority to preempt state regulation of the administration of private employer-sponsored health plans, states are blocked from enforcing laws interfering with ERISA.
As many states pursue health care reform experiments, ERISA preemption becomes relevant as a potential limit on the scope and type of reforms states are able to enact. The dominant trend in ERISA litigation has been to preempt state legislation and litigation interfering with the administration of private employer sponsored health plans, making large-scale state health care reform initiatives difficult. The purpose of this paper is to examine the trajectory of judicial interpretation of ERISA and to discuss what opportunities exist to facilitate health care initiatives given the constraints of ERISA preemption
Einstein-Aether Waves
Local Lorentz invariance violation can be realized by introducing extra
tensor fields in the action that couple to matter. If the Lorentz violation is
rotationally invariant in some frame, then it is characterized by an
``aether'', i.e. a unit timelike vector field. General covariance requires that
the aether field be dynamical. In this paper we study the linearized theory of
such an aether coupled to gravity and find the speeds and polarizations of all
the wave modes in terms of the four constants appearing in the most general
action at second order in derivatives. We find that in addition to the usual
two transverse traceless metric modes, there are three coupled aether-metric
modes.Comment: 5 pages; v2: Remarks added concerning gauge invariance of the waves
and hyperbolicity of the equations. Essentially the version published in PR
Demand modelling of passenger air travel: An analysis and extension. Volume 1: Background and summary
The framework for a model of travel demand which will be useful in predicting the total market for air travel between two cities is discussed. Variables to be used in determining the need for air transportation where none currently exists and the effect of changes in system characteristics on attracting latent demand are identified. Existing models are examined in order to provide insight into their strong points and shortcomings. Much of the existing behavioral research in travel demand is incorporated to allow the inclusion of non-economic factors, such as convenience. The model developed is characterized as a market segmentation model. This is a consequence of the strengths of disaggregation and its natural evolution to a usable aggregate formulation. The need for this approach both pedagogically and mathematically is discussed
Black holes and neutron stars in the generalized tensor-vector-scalar theory
Bekenstein's Tensor-Vector-Scalar (TeVeS) theory has had considerable success
as a relativistic theory of Modified Newtonian Dynamics (MoND). However, recent
work suggests that the dynamics of the theory are fundamentally flawed and
numerous authors have subsequently begun to consider a generalization of TeVeS
where the vector field is given by an Einstein-Aether action. Herein, I develop
strong-field solutions of the generalized TeVeS theory, in particular exploring
neutron stars as well as neutral and charged black holes. I find that the
solutions are identical to the neutron star and black hole solutions of the
original TeVeS theory, given a mapping between the parameters of the two
theories, and hence provide constraints on these values of the coupling
constants. I discuss the consequences of these results in detail including the
stability of such spacetimes as well as generalizations to more complicated
geometries.Comment: Accepted for publication in Physical Review
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Practical Issues in the Application of Direct Metal Laser Sintering
Direct Metal Laser Sintering (DMLS) was introduced to meet the objective of producing
metal parts directly from CAD data. CRDM has accumulated six years of experience in
applying this technique, mostly to prototyping parts for evaluation. For some applications,
such as blow moulds, porosity generated in DMLS has proved to be beneficial, but for others
a concession on tolerances or finish are necessary and/or complementary operations are
required, which add to manufacturing time and cost. This paper examines such issues
through some well chosen examples of parts to demonstrate both the strengths and
weaknesses of the DMLS process.Mechanical Engineerin
Passenger demographics and subjective response to commuter aircraft in the northeast
Results are compared for comfort and environmental studies taken in conjunction with a STOL program. Data were taken on flights of four different airlines, each flying different aircraft. Two of the lines are classified as commuter airlines flying between relatively close destinations. The aircraft involved are: the De Havilland Twin Otter, a Canadian aircraft; the French Nord 262; the Beechcraft 99 Airliner and the Sikorsky S-61 helicopter, both American
Development of thermionic converters Quarterly progress report
Design and fabrication of high efficiency, low power thermionic converters - graph
Reducing Distracted Driving: Regulation and Education to Avert Traffic Injuries and Fatalities
In this article, we consider the legal and policy implications of distracted driving (the tendency of people to use electronic devices while operating a motor vehicle). After reviewing the empirical evidence showing that distracted driving has serious adverse consequences, we discuss the legal basis for governmental interventions to reduce distracted driving. These interventions include laws restricting the use of electronic devices while driving, especially sending text messages. Since drivers have at best a reduced expectation of privacy, these restrictions should easily survive legal challenges. At the same time, it is important to consider the responsibility of automobile manufacturers to improve safety though design changes. We also advocate health education to change social norms to reduce distracted driving
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