We set up an electronic gradiometer for magnetocardiography (MCG) in an unshielded environment. The electronically balanced gradiometer consists of high-temperature radio-frequency superconducting quantum interference device (rf SQUID) magnetometers. The rf SQUID magnetometers are arranged to form the electronic first-order, four-vector gradiometer, or second-order gradiometer. The output of th...

We present the development of an algorithm for inverting multi-component gravity gradiometer data to recover three-dimensional (3-D) distributions of density contrast for salt imaging. The algorithm is a direct adaptation of the author’s earlier work on 3-D inversion of magnetic data. The underlying method is based upon a regularized inversion that constructs a density contrast distribution hav...

Since the launch of the GOCE satellite on March 17th 2009, a large amount of observation has been collected and needs to be analyzed. Of highest priority are the gradiometer measurements. Gravitational gradiometry measured in a satellite is new and many lessons are to be learnt before one can turn to a global gravity field analysis. Of highest priority is an analysis of the performance of (1) a...

SHORT ABSTRACT: This paper describes the theoretical analysis of a method to detect and classify objects from magnetic maps. The method, originally designed to detect buried UXO by land survey with a magnetometer, is adapted here for underwater survey with a gradiometer. Evaluation is performed on simulated data in order to predict the performance of the adapted algorithm to this new situation....

The recovery of a high resolution geopotential from satellite gradiometer observations motivates the examination of high performance computational techniques. The primary subject matter addresses specifically the use of satellite gradiometer and GPS observations to form and invert the normal matrix associated with a large degree and order geopotential solution. Memory resident and out-of-core p...

Recently, a novel Direct String Magnetic Gradiometer (DSMG) has been developed, where a vibrating wire, driven by an AC current, is used as a single sensitive element. It is designed to directly measure the local off-diagonal components of the magnetic gradient tensor, Bxz, Byz and Bxy, provided the distance to an object creating magnetic anomalies is much larger than the length of the string. ...

The gravity gradiometer is widely used in mineral prospecting, including in the exploration of mineral, oil and gas deposits. The mismatch of accelerometers adversely affects the measuring precision of rotating accelerometer-based gravity gradiometers. Several strategies have been investigated to address the imbalance of accelerometers in gradiometers. These strategies, however, complicate grad...

We have developed a superconducting phase gradiometer consisting of two parallel DNA-templated nanowires connecting two thin-film leads. We have ramped the cross current flowing perpendicular to the nanowires, and observed oscillations in the lead-to-lead resistance due to cross-current-induced phase differences. By using this gradiometer we have measured the temperatureand magnetic-field depen...

Vector arrow maps and isomagnetic maps were constructed with a second derivative SQUID (superconducting quantum interference device) gradiometer in normal subjects and in various pathological conditions to study the inverse problem of electromotive forces and to determine whether the magnetocardiogram (MCG) provides different information from the electrocardiogram (ECG). The current sources ded...

We demonstrate ElectroWetting-On-Dielectric (EWOD) transport and SQUID gradiometer detection of magnetic nanoparticles (MNPs) suspended in a 2 microl de-ionized water droplet. This proof-of-concept methodology constitutes the first development step towards a highly sensitive magnetic immunoassay platform with SQUID readout and droplet-based sample handling. Magnetic AC-susceptibility measuremen...