Geological controls on brine discharge in Itumbula Salt Dam within the Rukwa Rift in Momba District, Tanzania

The Itumbula salt dam of the Rukwa Rift Basin is a depression formed through extraction of spring-derived salt crystals. Brine yield by springs which is the primary cause of significant amounts of salt in the dam required further geological investigations to understand yield controls. In this study, detailed field geological investigations in the salt dam and its surroundings were conducted to ascertain brine discharge controls. These included documentation of lithology and surface manifestations of brine deposition. Geophysical methods (i.e. magnetic and electric surveys) for studying geologic structures associated with brine deposits, and laboratory analysis of cations and anions (e.g. chlorides, bicarbonates or sulphates) essential to characterize composition of waters were also performed. The information on the springs discharge rate was retrieved from the previous studies. The magnetic profile revealed a very low magnetic anomaly across the salt dam, trending NW to SE direction, which is interpreted to be the main structure that controls fluid movements in the dam. Electric resistivity survey results delineated a low resistivity body in the central part of the dam interpreted as porous formation with saline water. Hydro-chemistry of the hot spring brines indicated high levels of sodium and chloride ions contents than magnesium, calcium, potassium, sulphate, and carbonate and bicarbonate ions, interpreted to be mature water with minimal water mixing. The structurally controlled brines of approximately 2.5 kg/s are discharged in the study area. Keywords: Geologic Structures, Brine, Salt Production, Momba, Rukwa Basin.

Reporting the magnetic profile of cobalt ferrite nanoparticles at different temperatures

Cobalt ferrite nanoparticles (CFNs) were synthesized using cobalt nitrate hexahydrate and ferric nitrate nonahydrate through a wet chemical method. Various characterization techniques were used to confirm the synthesis of CFNs. The thermal stability, structure, morphology and crystallinity of the synthesized CFNs were determined by thermogravimetric analysis, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. The results show that the synthesized nanoparticles are stable and crystalline with fine homogenized structure. Vibrating sample magnetometry was used to determine the magnetic properties of the synthesized material. The coercivity was noted to be decreased and the hysteresis loop gradually flattens as the temperature increases toward the Curie temperature.

Application of Magnetic Sensor for Magnetic Profile (1D) and Surface (2D) Measurement of Automotive Wheels

This paper shows a report of over three years of intensive work on application of a 3-axis anisotropic magnetoresistive sensor with I2C interface for measurement of magnetic flux density distribution of automotive wheels. The work was undertaken to answer the question of whether is a possibility to effectively apply low-cost magnetic sensors with serial interface to measure the magnetic field surrounding the automotive wheel or tire. Two measurement techniques were discussed: Magnetic profile (1D) and magnetic surface measurement (2D) over tread, and also gear associated with the sensor, as well as its design, layout, operation, and control technique during (1D) and (2D) measurements. Three experiments were performed to asses accuracy and repeatability concerning component and resultant magnetic circumferential profiles and also magnetic surface. Differences between measurement outcomes in experiment were assessed. The results show that accuracy and repeatability lays below maximum admissible uncertainty declared by the producer. This proves directly that there is no measurable influence of motors, gear, operation, or measurement procedure on results obtained by magnetic sensors, and indirectly, that the assumed requirements regarding gear design and parameters are correct, and measurement of magnetic flux density distribution of automotive wheels and tires using (1D) and (2D) techniques is possible using a 3-axis anisotropic magnetoresistive sensor with I2C interface.

General features of the linear crystalline morphology of accretion disks

In this paper, we analyze the so-called Master Equation of the linear backreaction of a plasma disk in the central object magnetic field, when small scale ripples are considered. This study allows to single out two relevant physical properties of the linear disk backreaction: (i) the appearance of a vertical growth of the magnetic flux perturbations; (ii) the emergence of sequence of magnetic field O-points, crucial for the triggering of local plasma instabilities. We first analyze a general Fourier approach to the solution of the addressed linear partial differential problem. This technique allows to show how the vertical gradient of the backreaction is, in general, inverted with respect to the background one. Instead, the fundamental harmonic solution constitutes a specific exception for which the background and the perturbed profiles are both decaying. Then, we study the linear partial differential system from the point of view of a general variable separation method. The obtained profile describes the crystalline behavior of the disk. Using a simple rescaling, the governing equation is reduced to the second-order differential Whittaker equation. The zeros of the radial magnetic field are found by using the solution written in terms Kummer functions. The possible implications of the obtained morphology of the disk magnetic profile are then discussed in view of the jet formation. GraphicAbstract

Inversion and magnetization homogeneity testing for 2D magnetic sources

Many approaches to magnetic data inversion are based on assumptions that source magnetization is homogeneous in direction and intensity. Such assumptions rarely can be verified with independent geologic information and are usually incorporated without further inquiry in the next steps of data interpretation. The use of magnetization direction invariants, such as the gradient intensity of the total field anomaly (equivalent to the amplitude of the analytical signal [ASA]) and the intensity of the anomalous vector field (IAVF), is effective for modeling sources with strong remanent magnetization, usually with unknown direction. Even in such cases, however, the assumption of uniform magnetization is understood but unchecked when seeking smooth or compact solutions from data inversion. We have developed a procedure to test the assumption of uniform magnetization for 2D sources. For true 2D homogeneous sources, the ratio of ASA to IAVF can be modeled with a binary solution (0 and 1) regardless of the real value of the magnetization. A procedure to provide convergence was applied, and its output solution was submitted to a binary test to verify the uniformity hypothesis. This technique was illustrated with numerical simulations and then used to reinterpret a ground magnetic profile across an intrusive diabase body in sediments of the Paraná Basin, Brazil, revealing the existence of two adjacent bodies that are homogeneous with different magnetization intensities.

Multifrequency Vector Measurement System for Reliable Vehicle Magnetic Profile Assessment

This paper describes the design and the performance of simultaneous, multifrequency impedance measurement system for four inductive-loop (IL) sensors which have been developed for vehicle parameters measurement based on vehicle magnetic profile (VMP) analysis. Simultaneous impedance measurement on several excitation frequencies increases the VMP measurement reliability because typical electromagnetic interferences (EMI) are narrowband, and should not simultaneously affect, in the same way, all measurement bands that are spread in the frequency, i.e., it is expected that at least one measurement band is disturbance-free. The system consists of two standard and two slim IL sensors, specially designed and installed, the analogue front-end, and an industrial computer with digital-to-analogue and analogue-to-digital converters accessed via field-programmable gate array (FPGA). The impedance of the IL sensors is obtained by vector measurement of voltages from auto-balancing bridge (ABB) front-end. Complex voltages are demodulated from excitation frequencies with FIR filters designed with the flat-top windows. The system is capable of delivering VMPs in real-time mode, and also storing voltages for off-line postprocessing and analysis. Field distributions and sensitivities of slim and standard IL sensors are also discussed. Field test confirmed assumed increased reliability of VMP measurement for proposed simultaneous multifrequency operational mode.

Self-Assembly Properties of Amphiphilic Iron(III) Spin Crossover Complexes in Water and at the Air–Water Interface

The assembly properties of three known spin crossover iron(III) complexes 1–3, at the air–water interface, are reported. All three complexes are amphiphiles, each bearing a pair of Cn alkyl chains on the polyamino Schiff base sal2trien ligand (n = 6, 12, or 18). Complex 1 is water-soluble but complexes 2 and 3 form Langmuir films, and attempts were made to transfer the film of the C18 complex 3 to a glass surface. The nature of the assembly of more concentrated solutions of 3 in water was investigated by light scattering, cryo-SEM (scanning electron microscopy), and TEM (transmission electron microscopy), all of which indicated nanoparticle formation. Lyophilization of the assembly of complex 3 in water yielded a powder with a markedly different magnetic profile from the powder recovered from the initial synthesis, notably, the spin crossover was almost completely quenched, and the thermal behavior was predominantly low spin, suggesting that nanoparticle formation traps the system in one spin state.