The dc-to-dc converters employing staggered-phase power switches with two-loop control

A switched inductor voltage is coupled to a sense winding in each phase, and all sense windings are connected in series to one of two feedback loops to provide a signal that indicates when one of the power switches is on as the principal determinant of switching instants. A sequencer is triggered each time a pulse generator is triggered to turn on a different power switch in sequence at each switching instant

Phase substitution of spare converter for a failed one of parallel phase staggered converters

Failure detection and substitution of a spare module is provided in a system having a plurality of phase staggered modules connected in parallel to deliver regulated voltage from an unregulated source. Phase control signals applied to the active converter modules are applied to the spare module through NOR gates associated with and disabled by the power output of respective modules such that failure of any one enables its phase control signal to be applied to the spare module, thus controlling the spare module to operate in the phase position of the failed module. A NAND gate detects when any one active module fails and enables a gate in the spare module, thus activating the spare module

Unity power factor converter

A unity power factor converter capable of effecting either inversion (dc-to-dc) or rectification (ac-to-dc), and capable of providing bilateral power control from a DC source (or load) through an AC transmission line to a DC load (or source) for power flow in either direction, is comprised of comparators for comparing the AC current i with an AC signal i.sub.ref (or its phase inversion) derived from the AC ports to generate control signals to operate a switch control circuit for high speed switching to shape the AC current waveform to a sine waveform, and synchronize it in phase and frequency with the AC voltage at the AC ports, by selectively switching the connections to a series inductor as required to increase or decrease the current i

An Algorithm for Writing the Coefficients of a Polynomial with Given Zeros

Given a set of numbers {A1}=a1 …., an, we may represent the sum of the products, taken r at a time, of the first k numbers of the set by S(ai,r,k). Obviously S(ai,r,k)=S(ai,r,k-l)+akS (ai,r-1,k-1) for r, k\u3e1. If in addition we define S (ai,o,k) =1 for k\u3e0 the relation holds for r,k=0. Also S(ai,r,k)=O for

Low-Frequency Characterization of Switched dc-dc Converters

Averaging techniques are developed here to represent buck, boost, and buck-boost types of switched dc-dc converters by approximate continuous models. Simple analytical expressions in terms of the circuit components are derived for the characteristic transient and frequency responses of timeaveraged (continuous) power-stage models for use in designing and understanding the behavior of corresponding switched power stages. Novel conclusions include the dependence of effective circuit component values upon switch duty ratio and the existence of a real positive zero in certain transfer functions. Responses from analog computer simulations of the switched and averaged power stages agree well and, in turn, confirm the analytic predictions. High-order systems can be analyzed by the averaging technique without a commensurate increase in complexity

The Greater Awyu language family of West Papua

Healey (1970) and Voorhoeve (2001) established the Awyu-Dumut family of Papuan languages in the Digul Basin of West Papua and presented a proto Awyu-Dumut phonology. This paper presents an outline of a proto AwyuDumut morphology and discusses the linguistic position of Korowai and Kombai in relation to the Awyu-Dumut family. It is argued that Korowai is not a member of the Awyu-Dumut family but a member of a sister branch of Awyu-Dumut within a larger genetic group that we call Greater Awyu. Kombai is a member of the Awyu-Dumut family but is not a member of one of the two subgroups, Awyu and Dumut, proposed by Healey (1970). Rather, Kombai is a member of a third subgroup that we call the Ndeiram subgroup of the Awyu-Dumut family

Search for antiproton decay at the Fermilab Antiproton Accumulator

A search for antiproton decay has been made at the Fermilab Antiproton Accumulator. Limits are placed on thirteen antiproton decay modes. The results include the first explicit experimental limits on the muonic decay modes of the antiproton, and the first limits on the decay modes e- gamma gamma, and e- omega. The most stringent limit is for the decay mode pbar-> e- gamma. At 90% C.L. we find that tau/B(pbar-> e- gamma) > 7 x 10^5 yr. The most stringent limit for decay modes with a muon in the final state is for the decay pbar-> mu- gamma. At 90% C.L. we find that tau/B(pbar-> mu- gamma) > 5 x 10^4 yr.Comment: 20 pages, 8 figures. Submitted to Phys. Rev. D. Final results on 13 channels (was 15) are presente

Search for axion-like particles using a variable baseline photon regeneration technique

We report the first results of the GammeV experiment, a search for milli-eV mass particles with axion-like couplings to two photons. The search is performed using a "light shining through a wall" technique where incident photons oscillate into new weakly interacting particles that are able to pass through the wall and subsequently regenerate back into detectable photons. The oscillation baseline of the apparatus is variable, thus allowing probes of different values of particle mass. We find no excess of events above background and are able to constrain the two-photon couplings of possible new scalar (pseudoscalar) particles to be less than 3.1x10^{-7} GeV^{-1} (3.5x10^{-7} GeV^{-1}) in the limit of massless particles.Comment: 5 pages, 4 figures. This is the version accepted by PRL and includes updated limit

Ультразвуковое исследование при дегенеративно-дистрофических и воспалительных заболеваниях коленного сустава

Рассмотрены актуальные вопросы диагностики заболеваний коленного сустава − деформирующего остеоартроза, ревматоидного и псориатического артритов. Предложены критерии дифференциальной диагностики этих заболеваний.Urgent issues of diagnosis of knee joint diseases (osteoarthrosis deformans, rheumatoid and psoriatic arthritis) are discussed. The criteria of differential diagnosis are suggested