bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radial and angular correlation in heliumlike ions
Authors: Saha B. , Bhattacharyya S. , Mukherjee T. K. , Mukherjee P. K. 
Published: March 2003

AbstractIn the framework of nonrelativistic variational formalism a new type of basis set is proposed, to estimate separately the effect of radial and angular correlations on the ground‐state energy for helium isoelectronic sequence H− to Ar16+. Effect of radial correlation is incorporated by using multiexponential functions arising from product basis sets suitably formed out of Slater‐type one‐particle orbitals. The angular correlation can be switched on by incorporating an expansion in terms of basis involving interparticle coordinates. With a set of six‐term Slater‐type one‐particle basis and five‐term interparticle expansion, the ground‐state energy of helium is estimated as −2.9037236 (a.u.) compared with the multiterm variational estimates −2.9037244 (a.u.) due to Pekeris and Thakkar and Smith and Drake. Matrix elements of different operators in the ground state have been calculated and found to be in good agreement with available accurate results. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Useful parameter describing magnetic interactions in extended bis‐bidentate bridged dimers
Authors: Hu Haiquan , Chen Zhida , Liu Chengbu 
Published: March 2003

AbstractA useful parameter describing magnetic coupling interactions has been inspected in transition metal dimers, in which two transition metal ions are bridged by extended bis‐bidentate ligands. This parameter is the square of overlap integral between the spatial parts of magnetic orbitals in the broken symmetry state. The oxalato‐bridged Cu (II) dimers, in which the Cu (II) atom is either in tetrahedral or square pyramid coordination environment, have been calculated with the density functional theory coupling the broken symmetry approach. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Planar Translational Cable‐Direct‐Driven Robots
Authors: Williams Robert L. , Gallina Paolo , Vadia Jigar 
Published: March 2003

AbstractWe present the simulated dynamics and control of a planar, translational cable‐directdriven robot (CDDR). The motivation behind this work is to improve the serious cable interference problem with existing CDDRs and to avoid configurations where negative cable tensions are required to exert general forces and moments on the environment and during dynamic motions. Generally for CDDRs the commanded rotations are more demanding than commanded translations in terms of slack cable conditions. Therefore we propose a translational CDDR whose end‐effector may be fitted with a traditional serial wrist mechanism to provide rotational freedom (assuming proper design to resist the moments). Only the translational CDDR is considered in this article, including kinematics and statics modeling, statics workspace (wherein all possible Cartesian forces and moments may be exerted with only positive cable tensions), plus a dynamics model and simulated control for planar CDDRs. Here we focus only on planar CDDRs, to clearly demonstrate our dynamics and control work; we will extend this work to spatial CDDRs in the future. Examples are presented to demonstrate simulated control including feedback linearization of the four‐cable CDDR (with one degree of actuation redundancy) performing a Cartesian task. An on‐line dynamic minimum torque estimation algorithm is introduced to ensure all cable tensions remain positive for all motion; otherwise slack cables can result from CDDR dynamics and control is lost. © 2003 Wiley Periodicals, Inc.
Toledo Bend reservoir and geomorphic response in the lower Sabine River
Authors: Phillips Jonathan D. 
Published: March 2003

AbstractDownstream geomorphic responses of stream channels to dams are complex, variable, and difficult to predict, apparently because the effects of local geological, hydrological, and operational details confound and complicate efforts to apply models and generalizations to individual streams. This sort of complex geomorphic response characterizes the Sabine River, along the Texas and Louisiana border, downstream of the Toledo Bend dam and reservoir. Toledo Bend controls the flow of water and essentially prevents the flux of sediment from three‐quarters of the drainage basin to the lower Sabine River. Although the channel is scoured immediately downstream of the dam, further downstream there is little evidence of major changes in sediment transport or deposition, sand supply, or channel morphology attributable to the impoundment. Channels are actively shifting, banks are eroding, and sandbars are migrating, but not in any discernibly different way than before the dam was constructed. The Sabine River continues to transport sand downstream, and alluvial floodplains continue to accrete. The relatively small geomorphic response can be attributed to several factors. While dam releases are unnaturally flashy and abrupt on a day‐to‐day basis, the long‐term pattern of releases combined with some downstream smoothing creates a flow regime in the lower basin which mimics the pre‐dam regime, at least at monthly and annual time scales. Sediment production within the lower Sabine basin is sufficient to satisfy the river's sediment transport capacity and maintain pre‐dam alluvial sedimentation regimes. Toledo Bend reservoir has a capacity: annual inflow ratio of 1.2 and impounds 74% of the Sabine drainage basin, yet there has been minimal geomorphic response in the lower river, which may seem counterintuitive. However, the complex linked geomorphic processes of discharge, sediment transport and loads, tributary inputs, and channel erosion include interactions which might increase as well as decrease sediment loads. Furthermore, if a stream is transport‐limited before impoundment, the reduced sediment supply after damming may have limited impact. Copyright © 2003 John Wiley & Sons, Ltd.
Analysis and management of unseasonal flooding in the Barmah–Millewa Forest, Australia
Authors: Chong Joanne , Ladson Anthony R. 
Published: March 2003

AbstractThe Barmah‐Millewa Forest is the largest red gum forest in the world and lies adjacent to the middle reaches of Australia's River Murray. Regulation of the River Murray, to supply water for irrigation, has changed the watering regime of the forest and thus is degrading its environmental values. The watering regime has been changed in two ways: (1) there are now fewer large winter/spring events that inundate extensive areas because these floods are mitigated by irrigation storages; and (2) there are more small summer/autumn events that flood low‐lying areas and are caused by the way the river is operated to supply irrigation demand. The increased frequency of these small unseasonal floods is the subject of this paper.During the irrigation season, water to meet irrigation requirements must be released four days in advance to allow for travel time from storages to irrigation areas upstream of the Barmah‐Millewa Forest. If there is heavy summer rainfall, irrigators cancel their orders so the flow that would have been diverted, remains in the river and causes a small ‘rain rejection’ flood. At the same time, river freshets from unregulated tributaries can also increase river flows. The River Murray channel in this area has low capacity and these high flows result in water spilling into the forest. Based on analysis of pre‐regulation conditions (1908–1929) and current conditions (1980–2000), forest flooding has increased from 15.5% of days to 36.5% of days between December and April. In particular, small, localized floods, which cover less than 10% of the forest, occur at least eight times more frequently now, than before regulation. Work by others has related these hydrologic changes to tree death and changes in floristic structure in wetland systems. There are also economic costs because much of the water that spills into the forest is not available for irrigation.Two solutions to unseasonal flooding are described in this paper. One is to limit the maximum flow in the river during the irrigation season so there is capacity to convey at least some of the rain rejection flows without spilling water into the forest. The other is to maintain airspace in a diversion weir (Lake Mulwala) upstream of the forest to store the surplus water when orders are cancelled. Preliminary economic analysis shows the preferred option is to increase airspace in Lake Mulwala which provides net benefits of at least Aus$1.4 million per year along with unquantified environmental benefits from decreased unseasonal forest flooding. Copyright © 2003 John Wiley & Sons, Ltd.
Newton‐SOR method for fast statistical tomographic image reconstruction
Authors: Kudo Hiroyuki , Sawada Shinji 
Published: March 2003

AbstractThere are recent studies on image reconstruction for emission CT and transmission CT, using the maximum likelihood (ML) estimation or the maximum a posteriori (MAP) estimation, aiming at quality improvement of the reconstructed image. Those methods in general have the problem that minimization of the convex cost function by iterations is required, which increases the computational complexity. This paper proposes a new image reconstruction method, which requires less computation per iteration and realizes a fast convergence. The proposed method is based on the principle that the convex cost function is approximated in the iteration by a quadratic function, and the value of the quadratic function is reduced by SOR method, which is the solution procedure for the linear equation. The method can be called the Newton‐SOR method in the sense that both methods are combined. In order to guarantee global convergence of the Newton‐SOR method, mathematical techniques, called trust region and line search methods, are used, and the projection SOR method with the nonnegative condition is used, where a negative value appearing in the iteration is replaced by zero. The proposed method satisfies all of the desired properties of the iteration method as follows. (1) The convergence to the true solution minimizing the cost function is guaranteed. (2) The computational complexity per iteration is less, and a fast convergence is realized. (3) The method can be applied in a unified way to a wide range of convex cost functions. (4) The nonnegative condition can be handled easily. The effectiveness of the proposed method is demonstrated by a simulation experiment. The result of application to the clinical PET data is also shown. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(4): 1–11, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10178
CMOS Single‐chip Gas Detection Systems: Part II
Authors: Hagleitner C. , Hierlemann A. , Baltes H. 
Published: March 2003

AbstractSensor arrays based on industrial CMOS‐technology combined with post‐CMOS micromachining (CMOS MEMS) are a promising approach to low‐cost sensors. In the first part of this article [1], the state of research on CMOS‐based gas sensor systems was reviewed, and a platform technology for monolithic integration of three different transducers on a single chip was described. In this second part, the transduction principles of three polymer‐based gas sensors are detailed and the read‐out circuitry is portrayed. The first transducer is a micromachined resonant cantilever. The absorption of analyte in the chemically sensitive polymer causes shifts in resonance frequency as a consequence of changes in the oscillating mass. The cantilever acts as the frequency‐determining element in an oscillator circuit, and the resulting frequency change is read out by an on‐chip counter. The second transducer is a planar capacitor with polymer‐coated interdigitated electrodes. This transducer monitors changes in the dielectric constant upon absorption of the analyte into the polymer matrix. The sensor response is read out as a differential signal between the coated sensing capacitor and a passivated reference capacitor, both of which are incorporated into the input stage of a switched capacitor second‐order ΣΔ‐modulator. The third transducer is a thermoelectric calorimeter, which detects enthalpy changes upon ab‐/desorption of analyte molecules into a polymer film located on a thermally insulated membrane. The enthalpy changes in the polymer film cause transient temperature variations, which are detected via polysilicon/aluminum thermocouples (Seebeck effect). The small signals in the μV‐range are first amplified with a low‐noise chopper amplifier, then converted to a digital signal using a ΣΔ‐A/D‐converter and finally decimated and filtered with a digital decimation filter.
Market Data — Sensors in Household Appliances
Authors: Tschulena Guido R. 
Published: March 2003

AbstractIn Europe, the household industry produces millions of washing machines, dishwashers, cookers, refrigerators, home comfort appliances, small appliances, heating and climate control and security and safety‐related devices. Here, the use of sensors and microsystem products has a long tradition regarding relatively simple devices, such as temperature sensors or level sensors. However, the rate of introduction of new and improved sensors in household appliances has now increased, and the use of modern sensors with intelligent control systems is a key for differentiation between different appliance products and companies. Therefore, some more general sensor application areas are described, and also specific sensors which have been developed in recent years. Additionally, an outlook is given for possible new products and features which may be introduced in the future.
XPS in‐depth composition study on commercial monocrystalline silicon solar cells
Authors: Ariza M. J. , Martín F. , Leinen D. 
Published: March 2003

AbstractFrom large‐scale production, two monocrystalline silicon solar cells of different quality, i.e. ISC = 3.0 A (good cell) and ISC = 1.6 A (bad cell), have been studied by XPS combined with 4 keV Ar+ depth profiling. Depth profiling was carried out through the anti‐reflection coating (TiO2), the passivation layer (SiO2) and up into the phosphorus‐doped silicon bulk. At the solar cell surface the elemental composition is similar for both cells, although the bad one presents slightly more carbon, phosphorus and lead but less silver than the good one. During profiling, carbon and silver could be followed by XPS. It was found that the carbon content is distinguishably higher in the bad cell than in the good one. Furthermore, it was found that silver atoms have not diffused in the same way in both cells. Only the good cell presents silver atoms up into the silicon bulk. Copyright © 2003 John Wiley & Sons, Ltd.
Characterization of Sb2O3 subjected to different ion and plasma surface treatments
Authors: Reiche R. , Holgado J. P. , Yubero F. , Espinos J. P. , Gonzalez‐Elipe A. R. 
Published: March 2003

AbstractThis paper presents a study of Sb2O3 subjected to oxygen plasma and to ion beam bombardment (Ar+ and O2+ ions of 4 keV) by x‐ray photoelectron and reflected electron energy‐loss spectroscopies. Changes in stoichiometry (i.e O/Sb ratio) and oxidation state of Sb have been detected and correlated with the chemical and ballistic effects of the beams used for alteration of the Sb2O3 surface. Thus, oxygen plasma treatments lead to a significant oxidation of the surface layers of this material with the formation of up to 51% Sb5+ species as found by Sb 4d curve‐fitting analysis. By contrast, O2+ ion bombardment only produces a mild oxidation of the target with the formation of ∼13% Sb5+ species. Argon ion bombardment induces a complex process where Sb5+ and Sb0 species are formed simultaneously. This result has been discussed in terms of a disproportionation reaction of the type Sb3+ → Sb5+ + Sb0. The changes in the electronic properties of the treated material are consistent with the loss upon oxidation to Sb5+ of the valence states associated to the 5s2 electron pair of antimony. Approximate shapes of valence bands for Sb2O3 and Sb2O5 pure compounds have been extracted by applying factor analysis to valence band spectra of Sb2O3 subjected to different ion and plasma treatments. Copyright © 2003 John Wiley & Sons, Ltd.
Calculation of electron inelastic mean free paths (IMFPs) VII. Reliability of the TPP‐2M IMFP predictive equation
Authors: Tanuma S. , Powell C. J. , Penn D. R. 
Published: March 2003

AbstractWe report comparisons of electron inelastic mean free paths (IMFPs) determined from our predictive IMFP equation TPP‐2M and reference IMFPs calculated from optical data. These comparisons were made for values of the parameter Nv (the number of valence electrons per atom or molecule) that we have recommended and those that were recommended in a recent paper by Seah et al. (Surf. Interface Anal. 2001; 31: 778). The comparisons were made for eight elemental solids (K, Y, Gd, Tb, Dy, Hf, Ta and Bi) and two compounds (KBr and Y2O3) for which there were appreciable differences in the recommended Nv values from the two sources and for which optical data were available for the IMFP calculations. The average of the root‐mean‐square (RMS) deviations for the ten materials between IMFPs from the TPP‐2M equation with our Nv values and the reference IMFPs was 11.0%, whereas the corresponding average with the Seah et al. Nv values was 20.2%. The larger average in the latter comparison was mainly due to large (>20%) RMS deviations for four materials (K, Hf, Ta and KBr). For the other six materials, the RMS deviations with the Seah et al. values of Nv were similar to those with our values of Nv. Based on the comparisons for these ten materials, we believe that it is preferable to use our values of Nv in the TPP‐2M equation. Copyright © 2003 John Wiley & Sons, Ltd.
SIMS/XPS characterization of surface layers formed in 3 mass% Si‐steel by annealing in oxygen at low partial pressure
Authors: Suzuki S. , Yanagihara K. , Yamazaki S. , Tanaka K. , Waseda Y. 
Published: March 2003

AbstractSelective oxidation in silicon steel shows several interesting phenomena, such as the formation of an internal oxidation zone that depends on the oxidation conditions and the steel composition. In this work, SIMS and XPS were used for characterizing the formation processes of surface layers formed during selective oxidation of a typical silicon steel. The starting material is a secondary‐recrystallized 3 mass% Si‐steel sheet with a surface orientation of (011). Sample sheets were annealed at a temperature of 948–1023 K under an atmosphere with a low partial pressure of oxygen. The SIMS depth profiles show that the internal oxidation zone thickens and an iron‐rich layer that formed on the internal oxidation zone expands as the annealing temperature increases. Manganese and chromium levels increase outside the internal oxidation zone, whereas tin exists in the internal oxidation zone. The XPS results of the sample surface show that silicon and manganese levels increase on the sample surface to form oxides, and the chemical composition and state of these elements depend on the annealing temperature. In addition, tin increases on the surface of a relatively thick iron‐rich layer that formed on the internal oxidation layer. These experimental results are discussed on the basis of the thermodynamic characteristics of the elements. Copyright © 2003 John Wiley & Sons, Ltd.
Determination of photoelectron attenuation lengths in calcium phosphate ceramic films using XPS and RBS
Authors: Feddes B. , Vredenberg A. M. , Wolke J. G. C. , Jansen J. A. 
Published: March 2003

AbstractCalcium phosphate (CaP) coatings are used to improve the biological performance of an implant. A technique that is often used to measure the composition of this material is XPS. When extremely thin coatings are measured, for example to study the interface between CaP and a substrate, the quantification of the XPS results is complicated by the varying attenuation lengths (ALs) of the photoelectrons at different energies. To correct for this, AL data are needed. In this work we measured these ALs by comparing XPS yields with the coating coverage (as measured by Rutherford backscattering spectrometry). We were able to determine the AL for several calcium and phosphorus peaks. Determination of the oxygen ALs was not possible owing to diffusion of oxygen into the polymeric substrates. For the peaks that are most often used for quantification of XPS yields (the Ca 2p and the P 2p peak), we found ALs of 21.8 × 1015 atoms cm−2 and 26.8 × 1015 atoms cm−2, respectively. Concentration profiles near the interface, growth mode and interfacial roughness appeared to have no measurable effect on the measured ALs. For the ALs, an energy dependence with an exponent of 0.55 was found. The measured ALs are best predicted by the empirical CS1 equation of Cumpson and Seah. Copyright © 2003 John Wiley & Sons, Ltd.
Power and sample size calculations for generalized regression models with covariate measurement error
Authors: Tosteson Tor D. , Buzas Jeffrey S. , Demidenko Eugene , Karagas Margaret 
Published: March 2003

AbstractCovariate measurement error is often a feature of scientific data used for regression modelling. The consequences of such errors include a loss of power of tests of significance for the regression parameters corresponding to the true covariates. Power and sample size calculations that ignore covariate measurement error tend to overestimate power and underestimate the actual sample size required to achieve a desired power. In this paper we derive a novel measurement error corrected power function for generalized linear models using a generalized score test based on quasi‐likelihood methods. Our power function is flexible in that it is adaptable to designs with a discrete or continuous scalar covariate (exposure) that can be measured with or without error, allows for additional confounding variables and applies to a broad class of generalized regression and measurement error models. A program is described that provides sample size or power for a continuous exposure with a normal measurement error model and a single normal confounder variable in logistic regression. We demonstrate the improved properties of our power calculations with simulations and numerical studies. An example is given from an ongoing study of cancer and exposure to arsenic as measured by toenail concentrations and tap water samples. Copyright © 2003 John Wiley & Sons, Ltd.
Dynamic Cox modelling based on fractional polynomials: time‐variations in gastric cancer prognosis
Authors: Berger Ursula , Schäfer Juliane , Ulm Kurt 
Published: March 2003

AbstractThe most popular model used for survival analysis is the proportional hazards regression model proposed by Cox. This is mainly due to its exceptional simplicity. Nevertheless the fundamental assumption of the Cox model is the proportionality of the hazards. For many applications, however, this assumption is doubtful. Proposals to extend the Cox model for non‐proportional hazards to allow for dynamic effect structures usually either depend on prespecifications or require non‐standard estimation techniques and are thus not favoured in application. Moreover, tests to verify the dynamic effect structures are not straightforward or lack omnibus power. In this paper we propose a flexible method for modelling dynamic effects in survival data within the Cox framework. The method is based on fractional polynomials as introduced by Royston and Altman. This allows for a transformation of the dynamic predictor which leads back to the conventional Cox model and hence fitting is straightforward using standard estimation techniques. In addition, it offers the possibility of easily verifying the existence of time‐variation. We describe a model selection algorithm which selects time‐varying effects only when evidence is given in the data. We illustrate the properties of the approach in a simulation study and compare it with other methods. In a survival study of gastric cancer patients, we apply the approach to analyse dynamic structures in the effects of prognostic factors. Copyright © 2003 John Wiley & Sons, Ltd.