Low Frequency Pulsed Resonant Converter for Energy Harvesting

A pulsed-resonant ac-dc converter and an integrated circuit (IC) controller have been designed, fabricated, and tested for harvesting energy from low-voltage (1.2V), low-power (1-100muW) energy transducers with output frequency in the 10-Hz-1-kHz range. Simulations using foundry models suggest that the silicon loss could be as low as 0.6muW, and the efficiency could reach 70%. With the IC experimentally packaged, the measured efficiency is between 50% and 70%, depending on the size and the loss in the resonant inductor     

Influence of surface tension on damping of the oscillations of a viscous incompressible fluid in a cylindrical channel

A numerical calculation is made of small oscillations of a viscous incompressible fluid that fills half of a horizontal cylindrical channel. The calculation is made with and without allowance for surface tension. The results of the calculation show that allowance for surface tension increases the damping of the oscillations. The general properties of problems of the normal oscillations of a heavy and capillary viscous incompressible fluid were studied in [1–3], in which the possibility of applying the Bubnov-Galerkin method to these problems was pointed out. A method for calculating the oscillations of a viscous incompressible fluid that partly fills an arbitrary vessel at large Reynolds numbers was developed in [3–5].Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 128–132, May–June, 1980.     

BENZOFUROCOUMARINS: NEW MONOFUNCTIONAL DNA-PHOTOBINDING AGENTS

Abstract— The tetracyclic furocoumarin 2H-benzofuro[3,2-g]-1-benzo-pyran-2-one and its 4 and/or II methyl analogues have been investigated in their DN A-photobinding properties. Spectrophotometric and radioactivity measurements show that these compounds exhibit prominent ability to bind to the polynucleotide double helix by covalent photoaddition of the furocoumarin 3,4 double bond.
Denaturation-renaturation experiments demonstrate that no cross-link of DNA chains occurs. Benzopsoralens can thus be considered as a new class of monofunctional DNA-photobinding agents.     

Design issues for the transformer in a low-voltage power supplywith high efficiency and high power density

Circuit model, design feasibility, and design tradeoffs are investigated for the transformer in 1.5-5 V power supplies with high efficiency and high power density. The transformer is constructed from a single or a matrix of pot cores and from interleaved planar windings. It has been determined theoretically and verified experimentally that such a transformer is realizable as long as the loss constraint is not severe (e.g. less than 0.5 W transformer loss per 100 W output). The primary source of loss is the winding, not the core, in 1.5 V/turn design. Measures to reduce the transformer height tend to increase transformer loss or volume     

Improved method to extract the short-circuit parameters of the BECM

The current method for extracting the short-circuit broadband extended cantilever model (BECM) parameters requires measurement of short-circuit currents, and is problematic over a wide frequency range, prohibiting each short-circuit parameter to be directly measured. The improved method presented herein eliminates the measurements of short-circuit currents. Each short-circuit BECM parameter is directly found from two measurements, an open-circuit voltage gain and a short-circuit admittance. The method is demonstrated for a published five-winding BECM.     

Application of field-based circuits to the modeling of magneticcomponents with hysteresis

A magnetic component with hysteresis is modeled as a network of field-based elemental subcircuits, whose currents and voltages are related to the dynamic electromagnetic fields in the component and an interface network, which couples the terminal voltages and currents to the field-based network. Such a model captures rate-dependent hysteresis, geometry, frequency and waveshape effects. Coupled transient simulation of the electromagnetic fields inside the core and circuit phenomena has been demonstrated using the Saber circuit simulator. The low-frequency inductances and hysteresis-related waveforms predicted by the model have been verified experimentally     

Radiolysis of 1-naphthol in aqueous solutions

The effects of absorbed doses, initial pH and 1-naphthol concentration onto its radiolysis in aqueous sulphuric and hydrochloric acids by gamma rays from ⁶⁰Co were investigated. Under the experimental conditions, 1-naphthol degradation yields increased with increasing the absorbed doses (0.3–3.0 kGy) and with decreasing the initial 1-naphthol concentration (20–1 ppm). It was found out that the hydrated electrons did not play any significant roles in 1-naphthol radiolysis, as the degradation yields were higher at pH₀ ~ 0.46 compared to those at pH₀ ~ 2.0–5.0. The corresponding radiolytic yields G(−1-naphthol) were (6.13 ± 1.00)) × 10⁻² and (5.11 ± 0.22) × 10⁻² μmol/J in sulphuric acids, (15.61 ± 3.85) × 10⁻² and (4.76 ± 0.48) × 10⁻² μmol/J in hydrochloric acids. 1-Naphthol degradation rates could be described by the kinetic equations of pseudo-first-order reactions. An empirical relation between the observed reaction constants k _D and the initial 1-naphthol concentrations was established, enabling to predict the absorbed doses required for a given treatment efficiency. Three products of 1-naphthol degradation were revealed using an HPLC/UV procedure.     

A Dual-Wavelength Fiber Laser Sensor System for Measurement of Temperature and Strain

A strain and temperature-sensing scheme based on a dual-wavelength fiber laser is demonstrated experimentally. By measuring the change in the wavelength separation of the two lasing wavelengths and the shift of any of two lasing wavelengths, the measured strain and temperature are very linear and have a strain sensitivity of 0.15 pm/muepsiv over a range of 0-2400 muepsiv and a temperature sensitivity of 14.3 pm/degC over a range of 22degC-230degC, respectively.     

Finite-element formulation of field-based subcircuits for modelingof magnetic components with hysteresis

A finite-element formulation is described for the development of field-based subcircuits for the elements in a magnetic component. Rate-dependent hysteresis, geometry, frequency and waveshape effects are captured in the modeling methodology. Coupled transient simulation of electromagnetic fields (inside the core) and circuit phenomena is demonstrated in a companion paper     

Polynomial operators and local approximation of solutions of pseudo-differential equations on the sphere

We study the solutions of an equation of the form Lu=f, where L is a pseudo-differential operator defined for functions on the unit sphere embedded in a Euclidean space, f is a given function, and u is the desired solution. We give conditions under which the solution exists, and deduce local smoothness properties of u given corresponding local smoothness properties of f, measured by local Besov spaces. We study the global and local approximation properties of the spectral solutions, describe a method to obtain approximate solutions using values of f at points on the sphere and polynomial operators, and describe the global and local rates of approximation provided by our polynomial operators. The research of this author was supported, in part, by grant DMS-0204704 from the National Science Foundation and grant W911NF-04-1-0339 from the U.S. Army Research Office