bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Electrodynamic Properties of Alkali Metals for Frequencies Much Smaller than the Debye Frequency
Authors: Czerwonko J. 
Published: July 2007

AbstractThe dielectric constant of polycrystalline alkali metals is studied for a longitudinal as well as a transversal of electromagnetic field. This quantity is computed explicitely in two limiting cases: the quasistatic limit and the quasihomogeneous limit. Only the collisionless region is considered. It is shown that the rf dielectric constant coincides with that for the infrared region in the quasistatic limit whereas both quantities differ in the quasihomogeneous limit. The collisionless region may be attainable rather at helium temperatures and for pure samples. The calculation method consists in application of correlation functions to the microscopic Fermi‐liquid theory.
Interaction of Prismatic Dislocations and Intrinsic Faults
Authors: Clarebrough L. M. 
Published: July 2007

AbstractPrismatic loops punched from voids in a quenched Cu+9.4 at% Al alloy interact with intrinsic Frank loops to give stable unfaulted regions in the Frank loops bounded by Shockley partials. Two reactions involving dissociation of dislocations with b = 1/2 〈110〉 are identified as nucleating the unfaulted regions. The stability of the unfaulted regions may be attributed to segregation of aluminium to the stacking fault or interaction between a Shockley partial and small defects.
Paramagnetic Studies on the Cu(II) Ion in Single Crystals in Square Planar Coordination
Authors: Biswas P. K. , Sengupta P. 
Published: July 2007

AbstractInvestigations are made to explain the nature of ligand field of Cu(II) complexes in copper bisacetylacetonate and calcium copper acetate hexahydrate having square planar coordination with the neighbouring oxygens, on the basis of the ligand field theory and attempts are made to fit the theoretical expressions of magnetic anisotropy and mean susceptibility with the experimental values in the temperature range 90 to 300 °K, consistently with available optical absorption data and g‐values.
Mössbauer Effect Study of Iron Impurity States in AgCl and NaCl
Authors: Hennig K. , Yung Kim 
Published: July 2007

AbstractThe analysis of the properties of Mössbauer spectra and the conditions of preparing crystals of AgCl and NaCl doped with 57Co enabled us to suggest microscopic interpretation for five different types of chemical associations of cobalt with vacancies and oxygen and OH− impurities. A change of charge from Fe++ to Fe+++ and the reverse change were observed at high temperatures.
A Theory of Dislocation Dynamics
Authors: Gradowczyk M. H. 
Published: July 2007

AbstractFor a continuous distribution of moving dislocations, differential equations are derived that describe crystal flow in terms of the stress tensor, particle velocity, and flux density vectors of the dislocations. Plasticity effects, the non‐existence of an equation of state, elastic waves, and waves of dislocation density are some of the topics discussed.
Mössbauer Measurements of the Debye‐Waller Factor of Gold in Platinum after Low‐Temperature Neutron Irradiation
Authors: Mansel W. , Vogl G. , Vogl W. , Wenzl H. , Barb D. 
Published: July 2007

AbstractPt197, which decays with 20 h half‐life to Au197, is produced by irradiation of platinum samples with reactor neutrons at 4.6 °K. At the same time structural lattice defects are formed. Using the Mössbauer effect of Au197, the Debye‐Waller factor of the gold atoms is measured. A reduction of up to approximately 10% in the Debye‐Waller factor is found, which is attributed to irradiation‐produced defects. This behaviour is interpreted in terms of an interaction of defects formed by thermal and fast neutrons. A change of the coupling constant of the Au197 atom to its neighbours is assumed to be responsible for the reduction of the Debye‐Waller factor.
Influence of Internal Stress on Thermally Activated Dislocation Motion in the Peierls Potential
Authors: Heinrich R. , Pompe W. 
Published: July 2007

AbstractAn investigation is made of the dependence of thermally activated motion of dislocations in the Peierls potential on internal stresses. In order to compute the mean strain rate the totality of these stresses is taken into account assuming a homogeneous or an inhomogeneous distribution of dislocations. It is found that the increase of the activation volume in the small stress range can be explained. The consequences of this theory with respect to the dependence of flow stress on temperature are discussed.
Measurement of the Total Magnetic Susceptibilities of Metals by NMR
Authors: Smithard M. A. , Wynn V. T. 
Published: July 2007

AbstractThe NMR technique for the measurement of magnetic susceptibilities is extended to include metals in polycrystalline and single crystal forms. Measurements were made on cylindrical samples of copper, silver, gold, aluminium, magnesium, and beryllium. In particular the variation in the magnetic susceptibility of a single crystal of beryllium is obtained as a function of its orientation in the magnetic field. The values for the two principal components of the susceptibility are shown to agree well with those obtained previously by a classical method.
The Kohler Rule of Hall Coefficient in Neutron‐Irradiated Aluminium at 4.6 °K
Authors: Böning K. , Fenzl H. J. , Welter J. M. , Wenzl H. 
Published: July 2007

AbstractAn investigation is made of the range of validity of the Kohler rule for the Hall coefficient of aluminium at 4.6 °K, by introducing structural defects with different concentration and configuration by low temperature reactor irradiation and subsequent annealing. – During irradiation the low field Hall coefficient R0 at first increases rapidly and even changes its sign. But as soon as the electron scattering is predominantly governed by the irradiation induced defects, the Hall coefficient R0 (being now slightly positive) remains constant during further irradiation and the Kohler rule is fulfilled, because then only the concentration of identical defects is enlarged. After step‐annealing again large changes of R0 occur, because the structural defects not only recombine but also rearrange to other configurations with different scattering behaviour.
Lattice Dynamics Model of KNO3 in Its Ferroelectric Phase
Authors: Teng M. K. 
Published: July 2007

AbstractIn order to study the lattice dynamics behaviour of KNO3 through the ferroelectric I → III transition, a model is proposed for the ferroelectric phase III. The frequencies of the three normal low frequency modes are calculated and compared with Raman data. Good agreement between calculated and observed frequencies is obtained. Furthermore, basing on the proposed model, it is suggested that in the I → III ferroelectric transition, the long range electrostatic force, which represents the principal contribution for a softening of the unstable mode, shows only a small temperature dependence in accordance with experimental Raman results.
Stage III Recovery of Copper Heavily Deformed in Torsion
Authors: Polák J. 
Published: July 2007

AbstractAn investigation is made of the stage III recovery of resistivity of copper heavily deformed in torsion at liquid nitrogen temperature. Isochronal and isothermal curves are analysed on the basis of existing theories to explain stage III. The experimental data support the hypothesis of mutual annihilation of interstitial atoms with vacancies; the migrating defect being an interstitial atom, e.g. in dumbbell configuration. The value of the migration energy E = (0.70 ± 0.02) eV and of the radius of the mutual annihilation (five lattice constants) are found.
Etude des spectres d'électroréflexion du GaSb
Authors: Alibert C. , Bordure G. 
Published: July 2007

AbstractLes spectres d'électroréflexion du GaSb ont été étudiés entre 1,5 et 4,3 eV. Les mesures ont été faites à la température ambiante par la méthode de l'électrolyte. Une hétérojonction GaSb‐Cu2S a permis de faire l'étude en fonction de la température. Nous avons montré que les transitions à 2,02 eV et à 2,48 eV provenaient d'un point critique M1 transverse.
Hartree‐Fock Energy Bands for Krypton
Authors: Lipari N. O. 
Published: July 2007

AbstractWe have computed the Hartree‐Fock energy bands for solid krypton. The method used has been the orthogonalized plane wave (OPW) method. Calculations have been performed at the points Γ, X, L of the first Brillouin zone. Among the most interesting results are: 1. the computed energy gap is of ≈ 15 eV, a value larger than the measured optical gap; 2. the p‐valence bands are relatively wide (≈ 2.8 eV). All these characteristics are in complete agreement with a previous Hartree‐Fock band calculation for argon. We have included many‐body effects using Fowler's theory of electronic polarization.
Infra‐Red Modulation Using Hot‐Electron Faraday Effect in n‐InSb
Authors: Chattopadhyay D. , Nag B. R. 
Published: July 2007

AbstractThe effect of a large static electric field on the infra‐red modulation due to free‐carrier Faraday rotation in n‐InSb has been studied theoretically, taking into account the variation of the effective mass due to carrier heating. The theoretical results are of the same order of magnitude as the experimental ones, but no exact agreement was found. It is further shown, that the contribution of the change in the momentum relaxation time to the alteration of the Faraday rotation is insignificant compared to that arising from the change of effective mass.
Geometric Analysis of Charged Dislocations in the Fluorite Structure
Authors: Brantley W. A. , Bauer Ch. L. 
Published: July 2007

AbstractVarious dislocation configurations are examined in the fluorite structure for the presence of long‐range electrostatic charge assuming slip systems of the {001} 〈110〉 type. It is concluded that neither pure edge or screw dislocations nor jogs and kinks on edge or screw dislocations need necessarily give rise to long‐range charge, although adsorption or desorption of anions and cations could give rise to such charge. Based on these results and existing experimental data, facility of dislocation glide and likelihood of charge transport by dislocations are assessed.
Electron Spin Resonance in Tetracyanoquinodimethan
Authors: Mookherji T. , Kulshreshtha A. P. 
Published: July 2007

AbstractTCNQ powders show an electron spin resonance with a g‐value of 1.9916 which varies very slightly with temperature. The peak‐to‐peak linewidth is constant at higher temperatures and increases upon cooling below about 260 °K. The temperature variation of the signal intensity gives spin activation energies of 0.06 and 0.03 eV.
Changes in the quality of abalone (Haliotis asinina Linnaeus) packaged under atmospheric air, vacuum and modified atmosphere
Authors: Sanguandeekul Romanee , Siripatrawan Ubonrat , Narakaew Vichaya 
Published: July 2007

AbstractChanges in the quality of abalone (Haliotis asinina Linnaeus) meat packaged under modified atmosphere (MA) of 40% CO2/30% O2/30% N2, vacuum and atmospheric air in polyvinylidene chloride (PVDC)/nylon/oriented polypropylene (OPP) pouches, and stored at 2 ± 1°C were investigated. Biochemical indices, such as pH, total volatile basic nitrogen (TVB‐N), and trimethylamine (TMA) and sensory evaluation, as well as total plate counts of packaged abalone meat were determined periodically. TMA was not affected by the packaging conditions, and remained low during storage periods. A decrease in pH of the MA packaged abalones during the storage reflected the apparent absorption of CO2. The content of TVB‐N slowly increased in the MA packaged abalone, whereas those stored in atmospheric air markedly increased during the storage. The sensory quality of MA packaged abalones was shown to be acceptable up to 15 days, while atmospheric and vacuum‐packaged abalones were not acceptable after 3 days of storage. Copyright © 2007 John Wiley & Sons, Ltd.
New method for aroma barrier testing
Authors: Vähä‐Nissi M. , Hjelt T. , Jokio M. , Kokkonen R. , Kukkonen J. , Mikkelson A. 
Published: July 2007

AbstractA new quasi‐isostatic permeation test method has been developed for aroma barrier testing. Aroma concentrations are measured as a function of time, while the compounds diffuse from the source cell containing the model aroma solution through the tested material to the receiving cell. This method is applicable for testing various materials such as uncoated and coated paper/paperboard, and polymer films. The method utilizes automatic gas sampling from the test cells to gas chromatography. Copyright © 2007 John Wiley & Sons, Ltd.
Ensemble‐based chemical data assimilation. I: General approach
Authors: Constantinescu Emil M. , Sandu Adrian , Chai Tianfeng , Carmichael Gregory R. 
Published: July 2007

AbstractData assimilation is the process of integrating observational data and model predictions to obtain an optimal representation of the state of the atmosphere. As more chemical observations in the troposphere are becoming available, chemical data assimilation is expected to play an essential role in air‐quality forecasting, similar to the role it has in numerical weather prediction. Considerable progress has been made recently in the development of variational tools for chemical data assimilation. In this paper we assess the performance of the ensemble Kalman filter (EnKF) and compare it with a state‐of‐the‐art 4D‐Var approach. We analyse different aspects that affect the assimilation process, and investigate several ways to avoid filter divergence. Results with a real model and real observations show that EnKF is a promising approach for chemical data assimilation. The results also point to several issues on which further research is necessary. Copyright © 2007 Royal Meteorological Society
ENT challenges at the small scale
Authors: Coulson C. J. , Reid A. P. , Proops D. W. , Brett P. N. 
Published: July 2007

AbstractBackgroundIn this paper we consider two relatively frequently performed operations in the field of ear, nose and throat (ENT) surgery and consider how they could be improved by using robotic applications. We consider currently available robots and propose theoretical robotic solutions.MethodsThe application of robotic systems for both cochlear implantation and endoscopic sinus surgery was considered. Currently available robotic systems were reviewed and those with potential use in ENT surgery were identified. For aspects of operations where there is no available technology, hypotheses are presented on how robots could help.ResultsThree robotic systems were identified with potential usage in ENT: the Pathfinder™ neurosurgical robot, the Acrobot® knee replacement system and the autonomous smart drill for drilling a cochleostomy.ConclusionsThe challenge for the future of ENT is being able to perform tasks beyond the level of human perception and abilities. The examples presented here demonstrate that microtechnologies could be used to reduce complications, decrease operating time and improve clinical results. Copyright © 2007 John Wiley & Sons, Ltd.
Determination of optimal non‐invasive patient fixation methods for use in robotic hip replacement surgery—an in vitro study
Authors: Schulz A. P. , Tarabolsi M. , Faber A. , Meiners J. , Kammal M. , Mantwill F. 
Published: July 2007

AbstractBackgroundA robotic system for the implantation of a total hip arthroplasty (THA) is currently under development. One of the goals of this system is non‐invasive patient fixation, aiding the robotic system by an infrared tracking system. To determine the extent of fixation that can be achieved by non‐invasive methods, an in vitro study was performed.MethodsIn cadaver testing, different non‐invasive fixation methods (Arthrex leg holder with tourniquet mechanism; arthroscopic leg holder with disposable foam inserts; gynaecological leg holder; Goepel knee crutch) were evaluated under load in different directions.ResultsDeviation was measured in the range 0.33–18.1 mm with up to 20 N load. The testing showed the pneumatic leg holder system to provide the highest stability, followed by an arthroscopic leg holder system with foam inserts.ConclusionsUse of a leg holder with foam inserts produced a stability that should enable tracking of the remaining deviation by the navigation system. We will therefore use this method in our future development of the robotic milling tool. Copyright © 2007 John Wiley & Sons, Ltd.
Curved multi‐tube device for path‐error correction in a needle‐insertion system
Authors: Terayama Motokazu , Furusho Junji , Monden Morito 
Published: July 2007

AbstractBackgroundNeedle insertion is an important procedure for the diagnosis and treatment of various diseases. A prototype curved multi‐tube device (CMTD) and system for performing computerized correction of path errors during needle insertion is described.MethodsThe CMTD provides two functional modes, the straight‐needle mode and the curved‐needle mode. This study describes the CMTD and path‐error correction, using a prototype needle‐insertion system in a trial with a simple water phantom.ResultsThe needle insertion procedure was performed precisely in the centre of an ultrasound image. The CMTD functioned with the inner needle extending properly from its sleeve to correct path errors.ConclusionsThe path‐error corrections by the CMTD in a needle‐insertion system were shown. The system's computer processing can successfully determine the needle path from the ultrasound image and automatically guide the CMTD to the target. Copyright © 2007 John Wiley & Sons, Ltd.
Minimization of needle deflection in robot‐assisted percutaneous therapy
Authors: Abolhassani Niki , Patel Rajni V. , Ayazi Farzam 
Published: July 2007

AbstractBackgroundNeedle deflection and tissue deformation are two problems encountered during needle insertion into soft, non‐homogeneous tissue. They affect the accuracy of needle placement, which in turn affects the effectiveness of needle‐based therapies and biopsies.MethodsIn this study, a needle is inserted using a robot with two degrees of freedom. The needle is modelled as a flexible beam with clamped support at one end, and its deflection is estimated using online force/moment measurements at the needle base. To compensate for the needle deflection, the needle is axially rotated through 180° . The needle deflection estimation data is used to find the insertion depths at which needle rotations are to be performed.ResultsA bevelled‐tip needle was inserted into animal tissue. The needle deflection at the target was reduced by about 90%. It was observed that minimization of needle deflection reduced tissue deformation. The proposed method reduced needle deflection more than when needle insertion was performed with constant rotation.ConclusionsEstimating needle tip position using online force/moment measurement improves the accuracy of robot‐assisted percutaneous procedures when imaging feedback is not available. Copyright © 2007 John Wiley & Sons, Ltd.
A prediction‐based nonlinear controller for stabilization of a non‐minimum phase PVTOL aircraft
Authors: Chemori A. , Marchand N. 
Published: July 2007

AbstractIn this paper, a nonlinear prediction‐based control approach is proposed for stabilization of planar vertical take‐off and landing (PVTOL) aircraft. This system has fewer control inputs than degrees of freedom (i.e. under‐actuated) and has unstable zero dynamics (i.e. non‐minimum phase). The proposed control approach is based on partial feedback linearization, which allows the emergence of a completely linearized sub‐state and internal dynamics. Then, optimal trajectories are proposed for the linearized variables, where the optimization objective is to enhance the behaviour and the stability of the internal dynamics. Stability analysis of the closed‐loop system is performed using a graphical tool based on Poincaré's section. The performance of the proposed scheme is illustrated through simulations. Copyright © 2007 John Wiley & Sons, Ltd.
Fast implementations and rigorous models: Can both be accommodated in NMPC?
Authors: Zavala Victor M. , Laird Carl D. , Biegler Lorenz T. 
Published: July 2007

AbstractIn less than two decades, nonlinear model predictive control has evolved from a conceptual framework to an attractive, general approach for the control of constrained nonlinear processes. These advances were realized both through better understanding of stability and robustness properties as well as improved algorithms for dynamic optimization. This study focuses on recent advances in optimization formulations and algorithms, particularly for the simultaneous collocation‐based approach. Here, we contrast this approach with competing approaches for online application and discuss further advances to deal with applications of increasing size and complexity. To address these challenges, we adapt the real‐time iteration concept, developed in the context of multiple shooting (Real‐Time PDE‐Constrained Optimization. SIAM: Philadelphia, PA, 2007; 25–52, 3–24), to a collocation‐based approach with a full‐space nonlinear programming solver. We show that straightforward sensitivity calculations from the Karush–Kuhn–Tucker system also lead to a real‐time iteration strategy, with both direct and shifted variants. This approach is demonstrated on a large‐scale polymer process, where online calculation effort is reduced by over two orders of magnitude. Copyright © 2007 John Wiley & Sons, Ltd.
Model‐based inquiries in chemistry
Authors: Khan Samia 
Published: July 2007

AbstractIn this paper, instructional strategies for sustaining model‐based inquiry in an undergraduate chemistry class were analyzed through data collected from classroom observations, a student survey, and in‐depth problem‐solving sessions with the instructor and students. Analysis of teacher–student interactions revealed a cyclical pattern in which students generated, evaluated, and modified (GEM) hypotheses throughout the course. It is hypothesized that sustained involvement in the GEM cycle contributed to students' engagement with scientific inquiry and model construction and revision. As such, GEM represents a promising approach toward achieving process and content goals in the undergraduate chemistry classroom. © 2007 Wiley Periodicals, Inc. Sci Ed, 91:877–905, 2007
Principle, practice and persona in Isambard Kingdom Brunel's patent abolitionism
Authors: MILLER DAVID PHILIP 
Published: July 2007

AbstractThe nineteenth-century engineering hero Isambard Kingdom Brunel was a prominent patent abolitionist in debates about the patent system in Britain. His opposition is usually regarded as principled, that is, based in liberal laissez-faire opposition to monopolies and to the constraints of bureaucracy. Against this it is argued that Brunel's views on patents evolved. As late as 1840, despite lessons about patents from the bad experiences of his father, Brunel could still consider taking out a patent himself, something that a decade later he denied he had ever contemplated. Brunel's engineering persona, his experiences and conduct of engineering practice were the base from which he eventually formulated principled opposition to the patent system. The paper examines his responses to importunate inventors who pestered him with inventions in the 1840s and elucidates how he dealt with the patented inventions of others that he wanted to use in his projects. It is suggested that for Brunel patent abolitionism was in effect a way of doing business before it became a political cause. The case suggests the value of approaching the history of patents and, by implication, of intellectual property more generally, through detailed examination of practices.