Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

Discipline
Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 208201 - 208230 of 5207136

Full-Text Articles in Entire DC Network

Cg Versus Minres: An Empirical Comparison, David Chin-Lung Fong, Michael Saunders Apr 2025

Cg Versus Minres: An Empirical Comparison, David Chin-Lung Fong, Michael Saunders

Sultan Qaboos University Journal For Science

For iterative solution of symmetric systems the conjugate gradient method (CG) is commonly used when A is positive definite, while the minimum residual method (MINRES) is typically reserved for indefinite systems. We investigate the sequence of approximate solutions generated by each method and suggest that even if A is positive definite, MINRES may be preferable to CG if iterations are to be terminated early. In particular, we show for MINRES that the solution norms are monotonically increasing when A is positive definite (as was already known for CG), and the solution errors are monotonically decreasing. We also show that the …

Go to article

Model Calibration In Option Pricing, Andre Loerx, Ekkehard W. Sachs Apr 2025

Model Calibration In Option Pricing, Andre Loerx, Ekkehard W. Sachs

Sultan Qaboos University Journal For Science

We consider calibration problems for models of pricing derivatives which occur in mathematical finance. We discuss various approaches such as using stochastic differential equations or partial differential equations for the modeling process. We discuss the development in the past literature and give an outlook into modern approaches of modelling. Furthermore, we address important numerical issues in the valuation of options and likewise the calibration of these models. This leads to interesting problems in optimization, where, e.g., the use of adjoint equations or the choice of the parametrization for the model parameters play an important role.

Go to article

A Superlinearly Convergent Penalty Method With Nonsmooth Line Search For Constrained Nonlinear Least Squares, Nezam Mahdavi-Amiri, Mohammad Reza Ansari Apr 2025

A Superlinearly Convergent Penalty Method With Nonsmooth Line Search For Constrained Nonlinear Least Squares, Nezam Mahdavi-Amiri, Mohammad Reza Ansari

Sultan Qaboos University Journal For Science

Recently, we have presented a projected structured algorithm for solving constrained nonlinear least squares problems, and established its local two-step Q-superlinear convergence. The approach is based on an adaptive structured scheme due to Mahdavi-Amiri and Bartels of the exact penalty method. The structured adaptation also makes use of the ideas of Nocedal and Overton for handling the quasi-Newton updates of projected Hessians and appropriates the structuring scheme of Dennis, Martinez and Tapia. Here, for robustness, we present a specific nonsmooth line search strategy, taking account of the least squares objective. We also discuss the details of our new nonsmooth line …

Go to article

A New Criterion For Optimality In Nonlinear Programming, L.M. Graña Drummond, A.N. Iusem Apr 2025

A New Criterion For Optimality In Nonlinear Programming, L.M. Graña Drummond, A.N. Iusem

Sultan Qaboos University Journal For Science

We establish a sufficient condition for the existence of minimizers of real-valued convex functions on closed subsets of finite dimensional spaces. We compare this condition with other related results.

Go to article

Robust Resistance Network Topology Design By Conic Optimization, C. Roos, Y. Bai, D. Chaerani Apr 2025

Robust Resistance Network Topology Design By Conic Optimization, C. Roos, Y. Bai, D. Chaerani

Sultan Qaboos University Journal For Science

After a brief introduction to the field of Conic Optimization we present an application to the (robust) resistor network topology design problem, where the goal is to design an electrical network containing resistors, such that the dissipation is minimal, given the external current values at the nodes of the network and assuming that the conductance values satisfy some normalizing constraint. We present a linear model for the single-current case and semidefinite models for multi-current cases. All models are illustrated by examples.

Go to article

Solving The Flood Propagation Problem With Newton Algorithm On Parallel Systems, Chefi Triki Apr 2025

Solving The Flood Propagation Problem With Newton Algorithm On Parallel Systems, Chefi Triki

Sultan Qaboos University Journal For Science

In this paper we propose a parallel implementation for the flood propagation method Flo2DH. The model is built on a finite element spatial approximation combined with a Newton algorithm that uses a direct LU linear solver. The parallel implementation has been developed by using the standard MPI protocol and has been tested on a set of real world problems.

Go to article

Micellar Enhanced Ultrafiltration For The Removal Of Polycyclic Aromatic Hydrocarbons (Pahs) Mixtures In Underground Contaminated Water In Oman, Mohamed Aoudia, Amal Al-Sabahi, Salma Al-Kindy, Mahfoodh Al-Sheily, Fouzul Marikar Apr 2025

Micellar Enhanced Ultrafiltration For The Removal Of Polycyclic Aromatic Hydrocarbons (Pahs) Mixtures In Underground Contaminated Water In Oman, Mohamed Aoudia, Amal Al-Sabahi, Salma Al-Kindy, Mahfoodh Al-Sheily, Fouzul Marikar

Sultan Qaboos University Journal For Science

In an attempt to analyze polycyclic aromatic hydrocarbons (PAHs) in diesel contaminated underground water in Oman (Rustaq), Gas chromatography-Mass spectrometry was first used to determine the different concentrations in a standard mixture containing 16 PAHs. Retention time and calibration curves were obtained for all aromatic compounds and were used to identify a given analyte as well as its concentration in the contaminated underground water. Micellar enhanced ultrafiltration (MEUF) was then used to treat standard aqueous solution of PAHs at low concentration (~ 1 ppb) using an edible nonionic surfactant (Tween 80). The totality of the mixture components was completely rejected. …

Go to article

Environmental Aspects Of The Accelerated Urbanization In Sana’A, Yemen, Ahmed M. Alderwish, Fayad A. Alderwish Apr 2025

Environmental Aspects Of The Accelerated Urbanization In Sana’A, Yemen, Ahmed M. Alderwish, Fayad A. Alderwish

Sultan Qaboos University Journal For Science

From an environmental viewpoint, the prevailing health problems must be a “first priority” in all major development projects. Public water supply provides only 36% of domestic water. Disinfection of public water supply from the south well field is essential to avoid health problems. About 60% of the drinking water sold by ‘hygienic’ stations is of questionable quality. Expansion and upgrading in hospitals, pharmacies and industries (waste producers) will have an immediate impact on the amount of hazardous waste that will have to be disposed of. To achieve a sustainable urban development and to avoid environment/resources degradation, care should be taken …

Go to article

Surface Morphology Of Cus Thin Films Observed By Atomic Force Microscopy, Anuar Kassim, Ho Soon Min, Lim Kian Siang, Saravanan Nagalingam Apr 2025

Surface Morphology Of Cus Thin Films Observed By Atomic Force Microscopy, Anuar Kassim, Ho Soon Min, Lim Kian Siang, Saravanan Nagalingam

Sultan Qaboos University Journal For Science

CuS thin films were deposited onto microscope glass substrates using the chemical bath deposition method in the presence of tartaric acid as a complexing agent. The objective of this paper was to study the influence of the deposition time on the morphology of thin films. The surface morphology of the thin films was investigated using atomic force microscopy. The thin films deposited for the shortest time were found to be uniform, without cracks and with a dense surface morphology covering the entire substrate surface area. However, the films prepared for 60 min and above indicated incomplete coverage of the material …

Go to article

Synthesis Of Highly Ordered Crystalline Wurtzite (Zno) Membrane For Selenium-Chromium Separation, Sh. Labib, N.A. Tadros Apr 2025

Synthesis Of Highly Ordered Crystalline Wurtzite (Zno) Membrane For Selenium-Chromium Separation, Sh. Labib, N.A. Tadros

Sultan Qaboos University Journal For Science

Pure ZnO and composite ZnO-CeO2 coated thin films on titania substrates were prepared using a chelating sol-gel method under controlled conditions to be used in the separation and/or rejection of Se(IV) and Cr(VI). XRD and SEM studies confirmed the formation of highly ordered arrays of crystalline wurtzite microstructure with mixed orientation. An increase in average particle size of the prepared membranes from 1.25 to 3 µm with increasing CeO2 percent was observed indicating the vital role of CeO2 as secondary phase in improving the crystallinity of the coated films formed. Detailed study of the separation performance of the selected membranes …

Go to article

Spectral Analysis Of Magnetic Anomalies Due To A 2-D Horizontal Circular Cylinder: A Hartley Transforms Technique, Mansour A. Al-Garni Apr 2025

Spectral Analysis Of Magnetic Anomalies Due To A 2-D Horizontal Circular Cylinder: A Hartley Transforms Technique, Mansour A. Al-Garni

Sultan Qaboos University Journal For Science

The spectral analysis of the vertical effect of magnetic anomalies due to a 2-D horizontal circular cylinder is presented using Hartley transform. Hartley transform is an alternative approach to the famous complex Fourier transform. The depth to the center of the horizontal cylinder can be computed by a simple equation as a function of frequency. A synthetic example has been used to illustrate this technique and the validity of this approach has been proved by applying it to real data of a narrow band of quartz-magnetite in Mangampalli near Karimnagar town, India. The noise analyses were tested on the technique …

Go to article

Ground Radiometric Method As A Tool For Determining The Surface Boundary Of A Buried Bauxitic Karst, Kamal Kareem Ali, Salih Muhammad Awadh, Jassim Muhammad Hemad Apr 2025

Ground Radiometric Method As A Tool For Determining The Surface Boundary Of A Buried Bauxitic Karst, Kamal Kareem Ali, Salih Muhammad Awadh, Jassim Muhammad Hemad

Sultan Qaboos University Journal For Science

Forty two ground radiometric measurements along nine traverses within a rectangular network area were taken across a bauxitic karst within the Ubaid Formation (Lower Jurassic) in the Western Desert of Iraq. A 4-Channel Gamma Ray Spectrometer (GAD-6) with sodium iodide NaI (Tl) crystal (GSP-4S) was used in the field to measure the total radioactivity of the surface soil. Soil samples collected from the surface at each measurement point and core samples collected from a test well penetrating the karst were analyzed by Gamma ray spectrometer. The main objective of this study was to detect the hidden bauxitic karst and determine …

Go to article

On The Existence Of Evolutionary Learning Equilibriums, Masudul Alam Choudhury Apr 2025

On The Existence Of Evolutionary Learning Equilibriums, Masudul Alam Choudhury

Sultan Qaboos University Journal For Science

The usual kinds of Fixed-Point Theorems formalized on the existence of competitive equilibrium that explain much of economic theory at the core of economics can operate only on bounded and closed sets with convex mappings. But these conditions are hardly true of the real world of economic and financial complexities and perturbations. The category of learning sets explained by continuous fields of interactive, integrative and evolutionary behaviour caused by dynamic preferences at the individual and institutional and social levels cannot maintain the assumption of closed, bounded and convex sets. Thus learning sets and multi-system inter-temporal relations explained by pervasive complementarities …

Go to article

Chiral Polyhedra Derived From Coxeter Diagrams And Quaternions, Mehmet Koca, Nazife Ozdes Koca, Muna Al-Shueili Apr 2025

Chiral Polyhedra Derived From Coxeter Diagrams And Quaternions, Mehmet Koca, Nazife Ozdes Koca, Muna Al-Shueili

Sultan Qaboos University Journal For Science

There are two chiral Archimedean polyhedra, the snub cube and snub dodecahedron together with their dual Catalan solids, pentagonal icositetrahedron and pentagonal hexacontahedron. In this paper we construct the chiral polyhedra and their dual solids in a systematic way. We use the proper rotational subgroups of the Coxeter groups and to derive the orbits representing the solids of interest. They lead to the polyhedra tetrahedron, icosahedron, snub cube, and snub dodecahedron respectively. We prove that the tetrahedron and icosahedron can be transformed to their mirror images by the proper rotational octahedral group so they are not classified in the class …

Go to article

Dynamical Properties Of Omani Crude Oils For Flow Through A Vertical Annulus And A Cylindrical Pipe, Sayyadul Arafin, S.M. Mujibur Rahman Apr 2025

Dynamical Properties Of Omani Crude Oils For Flow Through A Vertical Annulus And A Cylindrical Pipe, Sayyadul Arafin, S.M. Mujibur Rahman

Sultan Qaboos University Journal For Science

We have initially investigated the temperature dependence of density and viscosity of a number of crude oils, collected from various hydrocarbon reservoirs in Oman. The measured data are then utilized to investigate the flow dynamics of these hydrocarbon fluids under gravity and applied pressures at various temperatures. We have modeled the flow of the various crude oil samples through a vertical (a) annulus and (b) cylindrical pipe - all treated within the Newtonian fluid flow approximation of a laminar flow - to investigate the flow properties of these samples. A computer program is developed so that the temperature dependence of …

Go to article

Comparison Of The Physiological Age Of Adult Resting Versus Flying Culex Quinquefasciatus (Diptera: Culicidae), D.M. Roberts Apr 2025

Comparison Of The Physiological Age Of Adult Resting Versus Flying Culex Quinquefasciatus (Diptera: Culicidae), D.M. Roberts

Sultan Qaboos University Journal For Science

Relatively little is known about the physiological age of resting mosquitoes. In this study, Culex quinquefasciatus Say had a similar proportion of males (75%) in the resting as in the flying population (76%), but among the females, there were significant differences between the physiological age of the resting and flying populations. The proportion of unfed females (51%) was significantly smaller in the resting than in the flying female group (82%). By contrast, in the resting group, there were much higher proportions of blood-fed (28% compared with 4%) and to a lesser extent gravid (21% compared with 14%) females. Of the …

Go to article

An Approach To Analyze The Ambiguity In Rna Structure, Shailendra Singh, Amardeep Singh Apr 2025

An Approach To Analyze The Ambiguity In Rna Structure, Shailendra Singh, Amardeep Singh

Sultan Qaboos University Journal For Science

DNA and RNA are two very important bio-molecules of the human cell. RNA is the second major form of nucleic acid in human cells that plays an intermediary role between DNA and functional protein. Several classes of RNA’s are found in cells, each with a / its distinct function. Understanding of storage and utilization of a cell’s genetic information is based on the structure of RNA. However, Many many experimental results have shown that RNA plays a another greater role in the cells. RNA sequences contains which contain signals at the structure level can be exploited to detect functional motifs …

Go to article

Study Of Ground Water Groundwater Potentiality And Sea Water Intrusion Along Along The Coastal Plain, Wadi Thuwal, Ksa- A Case Study Based On Dc Resistivity, Mansour A. Al-Garni, Hamdy I.E. Hassanein Apr 2025

Study Of Ground Water Groundwater Potentiality And Sea Water Intrusion Along Along The Coastal Plain, Wadi Thuwal, Ksa- A Case Study Based On Dc Resistivity, Mansour A. Al-Garni, Hamdy I.E. Hassanein

Sultan Qaboos University Journal For Science

The present study mainly aims to outline zones that have groundwater potentiality with good quality and those which are affected by sea water intrusion. The electrical resistivity data were acquired over an area of about 170 km2 of a coastal plain, Wadi Thuwal, which is bounded by the Red Sea in the west and the volcanic hills in the east. In such an area, resistivity measurements, using n-layering model, reveal generally reveal a wide range of resistivity values which do not reflect the reality. Hence, the statistical analysis has to be involved to overcome this problem and to make the …

Go to article

Screening And Purification Of A Chymotrypsin Inhibitor From Entrolobium Saman Seeds, Maher Ali. Maqtari, A.B. Mohamed. Saad Apr 2025

Screening And Purification Of A Chymotrypsin Inhibitor From Entrolobium Saman Seeds, Maher Ali. Maqtari, A.B. Mohamed. Saad

Sultan Qaboos University Journal For Science

A chymotrypsin inhibitor was isolated and purified from the seeds of Enterolobium saman (Leguminaceae family) by extraction with 100 mM phosphate buffer, heat treatment, ammonium sulphate precipitation, ion-exchange chromatography on DEAEcellulose and filtration through Sephadex G-75. The final preparation appeared to be homogeneous by both chromatographic and electrophoretic analyses. ESCI had a molecular weight of about 17,890 and an isoelectric point of 5.8. ESCI inhibited bovine chymotrypsin at an inhibitor-enzyme molar ratio of 1:2. The inhibition mode of chymotrypsin inhibitor was competitive on bovine chymotrypsin. Investigation has been carried out on the complex formed between chymotrypsin and chymotrypsin inhibitor by …

Go to article

Lithofacies Attributes Of A Transgressive Carbonate System : The Middle Eocence Seeb Formation, Al Khoud Area, Muscat, Oman, Osman Salad Hersi, Abdulrahman Al-Harthy Apr 2025

Lithofacies Attributes Of A Transgressive Carbonate System : The Middle Eocence Seeb Formation, Al Khoud Area, Muscat, Oman, Osman Salad Hersi, Abdulrahman Al-Harthy

Sultan Qaboos University Journal For Science

The Seeb Formation (Middle Eocene) is an about 600 m thick transgressive carbonate succession deposited in the Batina and Muscat coastal region of Oman. The formation consists of five informal, but distinct units, and their stacking architecture suggests a deepening-upward, shallow marine depositional setting. Unit I is characterized by cross-bedded, sandy, bioclastic packstones to grainstones deposited in a high energy beach-to-intertidal environment. Unit II consists of indistinctly bedded, nodular, bioclastic (mainly larger foraminifera) packstones and wackestones deposited in a logoonal lagoonal environment. Unit III is defined by medium to thickly bedded, bioclastic packestones to grainstones and subordinate, laterally confined conglomerates. …

Go to article

Formulas For The Number Of Spanning Trees In A Chain Of Cycles, Thomas Bier Apr 2025

Formulas For The Number Of Spanning Trees In A Chain Of Cycles, Thomas Bier

Sultan Qaboos University Journal For Science

We give a formula for the number of spanning trees in a chain of cycles that have connected intersection of one edge but where the cycles have variable sizes. The formula uses basic properties of continued fractions.

Go to article

Convective Hydromagentic Slip Flow With Variable Properties Due To A Porous Rotating Disk, Mohammad M. Rahman Apr 2025

Convective Hydromagentic Slip Flow With Variable Properties Due To A Porous Rotating Disk, Mohammad M. Rahman

Sultan Qaboos University Journal For Science

In this paper we investigate convective heat transfer characteristics of steady hydromagnetic slip flow over a porous rotating disk taken into account the temperature dependent density, viscosity and thermal conductivity in the presence of Hall current, viscous dissipation and Joule heating. Using von-Karman similarity transformations we reduce the governing equations for flow and heat transfer into a system of ordinary differential equations which are highly nonlinear and coupled. The resulting nondimensional equations are solved numerically by applying Nachtsheim-Swigert iteration technique. The results show that when modeling a thermal boundary layer, with temperature dependent fluid properties, consideration of Prandtl number as …

Go to article

Filtering And M-Ary Detection Of Markov Modulated Mean Reverting Model, Lakhdar Aggoun, Mohamed Al-Lawati, W.P. Malcolm Apr 2025

Filtering And M-Ary Detection Of Markov Modulated Mean Reverting Model, Lakhdar Aggoun, Mohamed Al-Lawati, W.P. Malcolm

Sultan Qaboos University Journal For Science

In an earlier paper we developed a stochastic model incorporating a double-Markov modulated mean-reversion model. The model is based on an explicit discretisation of the corresponding continuous time dynamics. Here we discuss parameter estimation via the technique of M-ary detection.

Go to article

An Electrophoretic Study Of Ldh-Isozyme Distribution In Developing Embryonic And Adult Tissues Of The Toad Bufo Arabicus, Intisar Ambusaidi, Taher Ba-Omar, Saif Al-Bahri, Aisha Al-Shihi Apr 2025

An Electrophoretic Study Of Ldh-Isozyme Distribution In Developing Embryonic And Adult Tissues Of The Toad Bufo Arabicus, Intisar Ambusaidi, Taher Ba-Omar, Saif Al-Bahri, Aisha Al-Shihi

Sultan Qaboos University Journal For Science

Lactate (LDH) dehydrogenases were studied by electrophoresis to investigate the possibility of isozymic differences in different stages and organs of B. arabicus embryos, tadpoles and adults. The expression pattern of lactate dehydrogenase (LDH) isozymes was analysed using nondenaturing discontinuous polyacrylamide gel electrophoresis (PAGE). Five LDH isozymes were observed in five different adult tissues. The most cathodal isozyme LDH-5 (A4) showed the strongest activity. All embryonic stages tested displayed the anodic isozymes first. Four LDH isozymes were present in the stages 1-16 (fertilized egg-tail bud stage). The first appearance of the fifth isozyme was detected in stage 17 when the muscular …

Go to article

Integumentary Histology Of The Amphibious Blenny, Isteblennius Edentulus (Forester And Schneider, 1801), Taher Ba-Omar, Maisoon M. Al-Riyami Apr 2025

Integumentary Histology Of The Amphibious Blenny, Isteblennius Edentulus (Forester And Schneider, 1801), Taher Ba-Omar, Maisoon M. Al-Riyami

Sultan Qaboos University Journal For Science

The skin of the amphibious blenny, Istiblennius edentulus, was studied using both light and scanning electron microscopy. Rich vascularisation was found immediately below the epidermis and the dermis. Surface epithelial cells displayed microridges in a fingerprint-like pattern. It was speculated that this increased surface area may aid in the adhesion of mucous secretions as well as to increase the surface area for gas exchange. The number of pores on the dorsal side (6.3x103 per mm2) was significantly higher than that on the ventral side (4.3x103 per mm2). The thickness of the skin on the dorsal side was measured at 31.6±10.0µm …

Go to article

Multiphase Mineral Inclusions In Ferrikaersutite Megacrysts : Implications For Postmagmatic Alteration Of The Kaersutite Host, Sobhi Nasir Apr 2025

Multiphase Mineral Inclusions In Ferrikaersutite Megacrysts : Implications For Postmagmatic Alteration Of The Kaersutite Host, Sobhi Nasir

Sultan Qaboos University Journal For Science

Primary and secondary multiphase mineral inclusions, without preserved fluid are found in ferrikaersutite megacrysts from the Cenozoic Harrat Ash Sham Volcanic Field in ٍSyria. Mineral phases in the inclusions are magnetite, hematite, pseudobrookite and pyrrhotite. The kaersutite megacrysts formed from a hydrous basanitic melt at depth. Silicate minerals in the inclusions are olivine, plagioclase, phlogopite, hornblende, clino- and orthopyroxene. These silicate minerals crystallized from melt penetration and infillings of veins and fractures in the kaersutite. Magnetite and pyrrhotite inclusion formed through magmatic crystallization which was followed by low temperature alteration and re-equilibration. Late stage near-surface alteration resulted in the formation …

Go to article

Pcr Based Detection Of Genetically Modified Soy In Processed Foods Commercially Available In Saudi Arabia, Ibrahim Abdullah Alaraidh Apr 2025

Pcr Based Detection Of Genetically Modified Soy In Processed Foods Commercially Available In Saudi Arabia, Ibrahim Abdullah Alaraidh

Sultan Qaboos University Journal For Science

In this research, PCR (polymerase chain reaction) technique was applied to detect the presence of GMO sold in the Saudi Arabian market. This method was applied to detect genetically modified soy (GM-soy) in particular the roundup ready soy (RRS). To confirm the presence of soy, samples were first tested for the existence of the soy specific lectin gene. A total of eighty samples were tested out of which two samples tested positive as GM-soy. Not surprisingly, the findings showed the existence of GM-soy in food products in Saudi. This supports the necessity of developing precise quantitative and qualitative ways for …

Go to article

Stability Of The Synchronization Manifold In An All-To-All Time Lag- Diffusively Coupled Oscillators, Adu A.M. Wasike Apr 2025

Stability Of The Synchronization Manifold In An All-To-All Time Lag- Diffusively Coupled Oscillators, Adu A.M. Wasike

Sultan Qaboos University Journal For Science

we consider a lattice system of identical oscillators that are all coupled to one another with a diffusive coupling that has a time lag. We use the natural splitting of the system into synchronized manifold and transversal manifold to estimate the value of the time lag for which the stability of the system follows from that without a time lag. Each oscillator has a unique periodic solution that is attracting.

Go to article

Transform Domain Characterization Of Dual Group Codes Of Cyclic Group Codes Over Elementary Abelian Groups, Adnan Abdulla Zain Apr 2025

Transform Domain Characterization Of Dual Group Codes Of Cyclic Group Codes Over Elementary Abelian Groups, Adnan Abdulla Zain

Sultan Qaboos University Journal For Science

The group of characters of an elementary Abelian group has been used to define duality between its subgroups, which in turn is extended to duality between group codes. The transform domain description of the dual codes of cyclic group codes of length over has been developed in this paper. Several example codes and their duals have been presented also.

Go to article

Anisotropy In Rfe2 Intermetallics: An Nmr Study, C Carboni Apr 2025

Anisotropy In Rfe2 Intermetallics: An Nmr Study, C Carboni

Sultan Qaboos University Journal For Science

The anisotropy of the Ho3+, Tb3+ and Tm3+ rare-earth ions in RFe2 compounds is investigated using the field dependence of the NMR spectra of 169Tm, 159Tb and 165Ho in polycrystalline TmFe2, TbFe2, HoFe2 and related pseudo-binary compounds. The very large hyperfine interaction in these ions dominates the NMR spectrum; the NMR frequencies in the 2 to 7 GHz range provide therefore a measure of the localized moment and its orientation in the crystal field. We compare the NMR measurements to single ion computations that include magnetostriction. KEYWORDS:

Go to article

First Prev Next Last