19,026 research outputs found
Multiobjective analysis for the design and control of an electromagnetic valve actuator
The electromagnetic valve actuator can deliver much improved fuel efficiency and reduced emissions in spark ignition (SI) engines owing to the potential for variable valve timing when compared with cam-operated, or conventional, variable valve strategies. The possibility exists to reduce pumping losses by throttle-free operation, along with closed-valve engine braking. However, further development is required to make the technology suitable for accept- ance into the mass production market. This paper investigates the application of multiobjective optimization techniques to the conflicting objective functions inherent in the operation of such a device. The techniques are utilized to derive the optimal force–displacement characteristic for the solenoid actuator, along with its controllability and dynamic/steady state performance
Low-momentum interactions in three- and four-nucleon scattering
Low momentum two-nucleon interactions obtained with the renormalization group
method and the similarity renormalization group method are used to study the
cutoff dependence of low energy 3N and 4N scattering observables. The residual
cutoff dependence arises from omitted short-ranged 3N (and higher) forces that
are induced by the renormalization group transformations, and may help to
estimate the sensitivity of various 3N and 4N scattering observables to
short-ranged many-body forces.Comment: 5 pages, 8 figures, to be published in Phys. Rev.
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