Uncertainty-principle noise in vacuum-tunneling transducers

The fundamental sources of noise in a vacuum-tunneling probe used as an electromechanical transducer to monitor the location of a test mass are examined using a first-quantization formalism. We show that a tunneling transducer enforces the Heisenberg uncertainty principle for the position and momentum of a test mass monitored by the transducer through the presence of two sources of noise: the shot noise of the tunneling current and the momentum fluctuations transferred by the tunneling electrons to the test mass. We analyze a number of cases including symmetric and asymmetric rectangular potential barriers and a barrier in which there is a constant electric field. Practical configurations for reaching the quantum limit in measurements of the position of macroscopic bodies with such a class of transducers are studied

Increasing of Reliability of Converter

The innovative activities in steel production invoke exploitation of new machines with the higher production capacity and productivity of labor. The paper deals with deformation and stress analysis of carrying parts of converter pedestal on the base of which the proposals and supporting measures were made that had the aim to increase reliability of the converter during steel production. This was achieved by lifespan prolongation of anchor and connecting bolts of converter pedestal, by change of stiffness of connected elements as well as by correction of nuts of bolted connections. The realization of structural changes decreased loading amplitudes and consequently the vibrations of pedestal. Solution was verified by numerical and experimental procedures of mechanics

Increasing of Reliability of Converter

The innovative activities in steel production invoke exploitation of new machines with the higher production capacity and productivity of labor. The paper deals with deformation and stress analysis of carrying parts of converter pedestal on the base of which the proposals and supporting measures were made that had the aim to increase reliability of the converter during steel production. This was achieved by lifespan prolongation of anchor and connecting bolts of converter pedestal, by change of stiffness of connected elements as well as by correction of nuts of bolted connections. The realization of structural changes decreased loading amplitudes and consequently the vibrations of pedestal. Solution was verified by numerical and experimental procedures of mechanics

Design of an RSFQ Control Circuit to Observe MQC on an rf-SQUID

We believe that the best chance to observe macroscopic quantum coherence (MQC) in a rf-SQUID qubit is to use on-chip RSFQ digital circuits for preparing, evolving and reading out the qubit's quantum state. This approach allows experiments to be conducted on a very short time scale (sub-nanosecond) without the use of large bandwidth control lines that would couple environmental degrees of freedom to the qubit thus contributing to its decoherence. In this paper we present our design of a RSFQ digital control circuit for demonstrating MQC in a rf-SQUID. We assess some of the key practical issues in the circuit design including the achievement of the necessary flux bias stability. We present an "active" isolation structure to be used to increase coherence times. The structure decouples the SQUID from external degrees of freedom, and then couples it to the output measurement circuitry when required, all under the active control of RSFQ circuits. Research supported in part by ARO grant # DAAG55-98-1-0367.Comment: 4 pages. More information and publications at http://www.ece.rochester.edu:8080/users/sde/research/publications/index.htm

Quantification of Residual Stresses in Hot Rolled Steel Sheets by the Hole Drilling Method

The paper deals with the problems of quantification of residual stresses in hot rolled sheets produced under various regimes. On the base of stress distribution along width and thickness of the belt is pointed out on possibilities of belt deformation from the plane as a result of action of torsional moment as an integral internal quantity in cross-section. For the non-uniformly distributed stresses along the thickness of the sheet the new method for residual stresses determination was developed. Application of the method is described in the paper

Quantum limit in resonant vacuum tunneling transducers

We propose an electromechanical transducer based on a resonant-tunneling configuration that, with respect to the standard tunneling transducers, allows larger tunneling currents while using the same bias voltage. The increased current leads to an increase of the shot noise and an increase of the momentum noise which determine the quantum limit in the system under monitoring. Experiments with micromachined masses at 4.2 K could show dominance of the momentum noise over the Brownian noise, allowing observation of the quantum-mechanical noise at the mesoscopic scale

The Strain Gage Method for Determination of Input Working Life Parameters of Pipes in Compressor Stations

For determination of safety operation of compressor stations and assessment of their residual working life is necessary to know the levels of residual stresses, operational loading as well as functionality of real support elements and influence of history of previous loading. The method described in the paper was verified several times during solution of problems concerning safety operation of piping yards. The method was also verified by the numerical methods of mechanics

Vrednovanje zaostalih naprezanja u zavaru metodom bušenja otvora

Residual stresses arise in the structures without loading during the technological processes, e.g. casting, rolling, welding, and pressing. In the paper is described the process of quantification of residual stresses by the hole-drilling method. For determination of residual stresses were used the procedures in which are supposed constant or linear distributions of stresses along the hole.Zaostala naprezanja nastaju u neopterećenim izradcima tijekom tehnoloških procesa, npr., pri odlijevanju, valjanju, zavarivanju i prešanju. U članku je opisan postupak vrednovanja zaostalih naprezanja u zavarenom spoju primjenom metode bušenja otvora. Za određivanje zaostalih naprezanja rabljen je postupak u kojemu se predmnijeva stalna ili linearna raspodjela naprezanja duž otvora

Vrednovanje zaostalih naprezanja u zavaru metodom bušenja otvora

Residual stresses arise in the structures without loading during the technological processes, e.g. casting, rolling, welding, and pressing. In the paper is described the process of quantification of residual stresses by the hole-drilling method. For determination of residual stresses were used the procedures in which are supposed constant or linear distributions of stresses along the hole.Zaostala naprezanja nastaju u neopterećenim izradcima tijekom tehnoloških procesa, npr., pri odlijevanju, valjanju, zavarivanju i prešanju. U članku je opisan postupak vrednovanja zaostalih naprezanja u zavarenom spoju primjenom metode bušenja otvora. Za određivanje zaostalih naprezanja rabljen je postupak u kojemu se predmnijeva stalna ili linearna raspodjela naprezanja duž otvora

Radio-Frequency Superconducting Parametric Transducer for Gravitational-Wave Antennae

We report on the design and testing of an ultrasensitive, electromechanical transducer for use on resonant mass gravitational wave antennae. The transducer is a superconducting, radio frequency resonant bridge circuit operating near 200 MHz. We have minimized several important sources of noise in this transducer system. The Johnson noise of the transducer circuit is reduced through using a superconducting niobium stripline circuit and low‐loss insulating materials. At a temperature of 4.2 K we have achieved unloaded electrical quality factors of 200 000. The bridge circuit is balanced by piezoelectric actuators which control the spacing between the proof mass and capacitive segments of the stripline circuit and we have achieved a residual bridge imbalance of 3×10−7. Finally, low noise cryogenically cooled field‐effect transistors are used for the first amplifier stage, enabling us to obtain an amplifier noise level which is 5400 times the quantum limit. The transducer, which has a 0.080 kg proof mass, was affixed to the end of a prototype, resonant bar, gravitational wave antenna with a mass of approximately 100 kg. The primary purpose of this small antenna was to evaluate the transducer, which is designed to be mounted on a much more massive antenna. Our theoretical analysis and measurements of the detector agree and indicate a burst noise temperature of 1.8 K using the 100 kg bar. This corresponds to a gravity wave burst sensitivity of h=1.1×10−16, in terms of relative strain amplitude. With no other improvements, if the transducer mechanically resonant frequency were tuned to and installed on a 2000 kg antenna, the antenna would reach a noise temperature of 1.3 mK, which is equivalent to a gravitational wave burst sensitivity, h≊5.7×10−19