253,191 research outputs found
Matter Effects in Active-Sterile Solar Neutrino Oscillations
The matter effects for solar neutrino oscillations are studied in a general
scheme with an arbitrary number of sterile neutrinos, without any constraint on
the mixing, assuming only a realistic hierarchy of neutrino squared-mass
differences in which the smallest squared-mass difference is effective in solar
neutrino oscillations. The validity of the analytic results are illustrated
with a numerical solution of the evolution equation in three examples of the
possible mixing matrix in the simplest case of four-neutrino mixing.Comment: 26 pages. Final version published in Phys. Rev. D80 (2009) 11300
Evolutionary L∞ identification and model reduction for robust control
An evolutionary approach for modern robust control oriented system identification and model reduction in the frequency domain is proposed. The technique provides both an optimized nominal model and a 'worst-case' additive or multiplicative uncertainty bounding function which is compatible with robust control design methodologies. In addition, the evolutionary approach is applicable to both continuous- and discrete-time systems without the need for linear parametrization or a confined problem domain for deterministic convex optimization. The proposed method is validated against a laboratory multiple-input multiple-output (MIMO) test rig and benchmark problems, which show a higher fitting accuracy and provides a tighter L�¢���� error bound than existing methods in the literature do
Implantable RF-coiled chip packaging
In this paper, we present an embedded chip integration
technology that utilizes silicon housings and flexible
parylene radio frequency (RF) coils. As a demonstration
of this technology, a flexible parylene RF coil has been
integrated with an RF identification (RFID) chip. The coil
has an inductance of 16 μH, with two layers of metal
completely encapsulated in parylene-C. The functionality
of the embedded chip is verified using an RFID reader
module. Accelerated-lifetime soak testing has been
performed in saline, and the results show that the silicon
chip is well protected and the lifetime of our
parylene-encapsulated RF coil at 37 °C is more than 20
years
Key Challenges and Opportunities in Hull Form Design Optimisation for Marine and Offshore Applications
New environmental regulations and volatile fuel
prices have resulted in an ever-increasing need for reduction
in carbon emission and fuel consumption. Designs of marine
and offshore vessels are more demanding with complex
operating requirements and oil and gas exploration
venturing into deeper waters and hasher environments.
Combinations of these factors have led to the need to
optimise the design of the hull for the marine and offshore
industry. The contribution of this paper is threefold. Firstly,
the paper provides a comprehensive review of the state-ofthe-
art techniques in hull form design. Specifically, it
analyses geometry modelling, shape transformation,
optimisation and performance evaluation. Strengths and
weaknesses of existing solutions are also discussed.
Secondly, key challenges of hull form optimisation specific
to the design of marine and offshore vessels are identified
and analysed. Thirdly, future trends in performing hull
form design optimisation are investigated and possible
solutions proposed. A case study on the design optimisation
of bulbous bow for passenger ferry vessel to reduce wavemaking
resistance is presented using NAPA software.
Lastly, main issues and challenges are discussed to stimulate
further ideas on future developments in this area, including
the use of parallel computing and machine intelligence
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