bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pd/C: A Recyclable Catalyst for Cyanation of Aryl Bromides
Authors: Zhu Yi‐Zhong , Cai Chun 
Published: April 2007

AbstractAryl cyanides have been prepared from the corresponding aryl bromides with potassium hexacyanoferrate(II) usingPd/C as a catalyst. It is shown that the addition of Bu3N is the key factor in obtaining the corresponding aryl cyanides. Furthermore, the catalyst can be recycled by filtration and washing sequences, making the method also attractive for industrial applications.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
General Behavior of the I–E and ΔI–E Curves Obtained when a Multistep Potential is Applied to an Electroactive Monolayer
Authors: Abenza Nuria , Gonzalez Joaquín , Molina Angela 
Published: April 2007

AbstractSimple, analytical and fully explicit expressions for the I–E curves of a charge transfer process of a diffusionless system corresponding to staircase voltammetry (SCV) are presented. We have analyzed the reversibility influence and our results indicate that SCV curves obtained at different sampled times tend to coincide as the rate constant decreases. Moreover, the current–potential SCV response converts to that corresponding to linear sweep voltammetry (LSV) when the pulse amplitude ΔE→0. We have also obtained the theoretical expression for the response of differential staircase voltammetry (DSCV) which presents two peaks and a cross potential at which ΔI=0.
Amide and Acyl‐Hydrazine Functionalized Calix[4]arenes as Carriers for Hydrogen Phosphate Selective Electrodes
Authors: Yan Zhenning , Li Xia , Xu Yan , Ye Baoxian 
Published: April 2007

AbstractAnion‐selective solvent polymeric membrane based on hydrogen bond‐forming, neutral ionophores with amide or acyl‐hydrazine groups are described. The use of the two calix[4]arenes results in anion‐selective electrodes with a selectivity for phosphate. The electrodes of the optimum characteristic have the composition of 1 wt% ionophore, 66 wt% o‐NPOE, 33 wt% poly (vinyl chloride) (PVC) and TDMACl (15 or 30 mol% relative to the ionophore 1 and 2, respectively). The optimized membrane electrodes show Nernstian responses towards monohydrogen phosphate (−29.1 and −29.3 mV/decade) based on ionophore 1 and 2, respectively, in a wide concentration range (1.0×10−5 to 1.0×10−2 or 1.0×10−5 to 1.0×10−1 M). The selectivity coefficients are determined with the fixed interference method and the activity ratio method. The electrodes display an anti‐Hofmeister series selectivity pattern and highly selective for HPO42− over Cl−, Br−, CH3COO−, NO3− and SO42−. The lifetime of the electrodes is at least 1 month and their response time is found to be 25 s. The proposed sensors could be put to analytical use both by direct potentiometry as well as potentiometric titration.
Electrocatalytic Reduction of H2O2 and Oxygen on the Surface of Thionin Incorporated onto MWCNTs Modified Glassy Carbon Electrode: Application to Glucose Detection
Authors: Salimi Abdollah , Noorbakhsh Abdollah , Mamkhezri Hussein , Ghavami Raoof 
Published: April 2007

AbstractA new H2O2 enzymeless sensor has been fabricated by incorporation of thionin onto multiwall carbon nanotubes (MWCNTs) modified glassy carbon electrode. First 50 μL of acetone solution containing dispersed MWCNTs was pipetted onto the surface of GC electrode, then, after solvent evaporations, the MWCNTs modified GC electrode was immersed into an aqueous solution of thionin (electroless deposition) for a short period of time <5–50 s. The adsorbed thin film of thionin was found to facilitate the reduction of hydrogen peroxide in the absence of peroxidase enzyme. Also the modified electrode shows excellent catalytic activity for oxygen reduction at reduced overpotential. The rotating modified electrode shows excellent analytical performance for amperometric determination of hydrogen peroxide, at reduced overpotentials. Typical calibration at −0.3 V vs. reference electrode, Ag/AgCl/3 M KCl, shows a detection limit of 0.38 μM, a sensitivity of 11.5 nA/μM and a liner range from 20 μM to 3.0 mM of hydrogen peroxide. The glucose biosensor was fabricated by covering a thin film of sol–gel composite containing glucose oxides on the surface of thionin/MWCNTs modified GC electrode. The biosensor can be used successfully for selective detection of glucose based on the decreasing of cathodic peak current of oxygen. The detection limit, sensitivity and liner calibration rang were 1 μM, 18.3 μA/mM and 10 μM–6.0 mM, respectively. In addition biosensor can reach 90% of steady currents in about 3.0 s and interference effect of the electroactive existing species (ascorbic acid–uric acid and acetaminophen) is eliminated. The usefulness of biosensor for direct glucose quantification in human blood serum matrix is also discussed. This sensor can be used as an amperometric detector for monitoring oxidase based biosensors.
Determination of Trace Amounts of Copper in Tap Water Samples with a Calix[4]arene Modified Carbon Paste Electrode by Differential Pulse Anodic Stripping Voltammetry
Authors: Canpolat Esra Çelik , Şar Erdem , Coşkun Naciye Yılmaz , Cankurtaran Hüsnü 
Published: April 2007

AbstractA calix[4]arene modified carbon paste electrode was used for trace determination of copper. The study of the preconcentration of copper as well as the other heavy metal ions at the modified electrode, with subsequent measurement by differential pulse anodic stripping voltammetry (DPASV), indicates the efficient open‐circuit accumulation of the analytes onto the electrode. Many parameters such as the composition of the paste, pH, preconcentration time and stirring rate influence the response of the measurement. The procedure was optimized for copper determination. For a 10‐minute preconcentration time at pH 6.5–7.5, the detection limit (LOD) was 1.1 μg L−1. The optimized method was successfully applied to the determination of copper in tap water sample by means of standard addition procedure. The copper content of the sample was comparable with the result obtained with AAS method.
Dynamic racking tests of curtain wall glass elements with in‐plane and out‐of‐plane motions
Authors: Behr R. A. , Belarbi A. , Culp J. H. 
Published: April 2007

AbstractThis project was conducted to investigate the breakage and fallout behaviour of various types of architectural glass elements in a dry‐glazed curtain wall system under in‐plane and out‐of‐plane dynamic motions. The project was a follow‐up to an earlier project that focused exclusively on in‐plane dynamic racking performance of curtain wall glass elements. The recent data indicated that adding out‐of‐plane motions caused significantly higher amounts of glass breakage and subsequent glass fallout in most glass types that were found during the in‐plane tests to be prone to glass fallout. Specifically, 1/4 in (6 mm) annealed monolithic glass, 1/4 in annealed monolithic glass with a 0·004 in (0·10 mm) PET film (not anchored to the mullions), and 7/16 in (11 mm) fully tempered laminated glass exhibited comparable or higher fallout rates than the already substantial fallout rates that were observed during the in‐plane only racking tests. Unanchored window film was found to be ineffective in resisting post‐breakage glass fallout under dynamic racking motions. In contrast, 1/4 in (6 mm) annealed laminated glass and 7/16 in (11 mm) heat‐strengthened laminated glass exhibited no glass fallout during the out‐of‐plane tests, just as they exhibited no fallout during the in‐plane tests. Out‐of‐plane test results also showed that 3/8 in (10 mm) heat‐strengthened monolithic glass exhibited no fallout, while 3/8 in annealed monolithic glass exhibited very negligible glass fallout. The addition of torsional motions was not found to induce glass fallout in those glass types that resisted glass fallout in previous tests performed without torsional motions.
Seismic fracture of koyna dam: Case study
Authors: Pekau O. A. , Lingmin Feng , Chuhan Zhang 
Published: April 2007

AbstractThe two numerical procedures previously presented by the authors to model crack closure during seismic fracture of concrete gravity dams are employed herein to study the 1967 performance of the Koyna dam. First, a brief description of the general procedure is given, followed by the detailed formulation of the force method for simulation of crack closure. The latter was introduced to prevent the hypothetical overlap phenomenon which was originally assumed in the modelling of crack closure by the impulse method. Also presented are the results obtained for a model of the Koyna dam tested on a shaking table to study the cracking process under simplified loading conditions. Satisfactory agreement between the test and numerical results is shown. Finally, the cracking process of the Koyna dam prototype subjected to the 1967 earthquake is evaluated numerically by employing the aforementioned techniques. From the results, it is concluded that both procedures for simulating the impact effect of crack closing predict complete penetration of the crack through the upper part of the dam, which is consistent with the observed prototype behaviour.
On building finite element models of structures from modal response
Authors: Hjelmstad K. D. , Banan MO. R. , Banan MA. R. 
Published: April 2007

AbstractWe develop two algorithms for estimating member stiffnesses and masses of a structure from measured modal response in conjunction with a finite element model of the structure. The mathematical model has known geometry and topology and parameterized constitutive properties. A few of the natural frequencies are measured and the corresponding modes are sampled at certain locations in space. The proposed algorithms are based on the concept of minimizing the sum of the squares of errors, specified as an index of discrepancy between the model and the structure, over all of the measured modes. The recursive quadratic programming method is used to solve the non‐linear constrained estimation problem. Both proposed estimators can handle incompletely measured models, have robust convergence, and are amenable to modelling of complex structures. We demonstrate the use of our parameter estimation algorithm by applying it to identify the properties of a building from measured data.
A system identification approach to the detection of changes in both linear and non‐linear structural parameters
Authors: Loh Chin‐Hsiung , Tou Iat‐Chun 
Published: April 2007

AbstractThis paper explores the potential of a new time domain identification procedure to detect changes in structural dynamic characteristics on the basis of measurements. This procedure is verified using mathematical models simulated on the computer. The experiments involve two eight‐storey steel structures with and without energy devices, and a 47‐storey building at San Francisco during the Loma Prieta earthquake. The recursive instrumental variable method and extended Kalman filter algorithm are used as identification algorithms. An exploratory investigation is made of the usefulness of various indices, such as mode shape and storey drift, that can be extracted accurately from identification to quantify changes in the characteristics of the physical system. It is concluded that the change of storey drift is the key information to the detection of changes in structural parameters, from which the proposed system identification algorithm can be applied with an appropriate inelastic model to simulate the dynamic behaviour of real structures undergoing strong ground motion excitations.
Three‐dimensional response of a layered cylindrical valley embedded in a layered half‐space
Authors: Luco J. E. , de Barros F. C. P. 
Published: April 2007

AbstractAn indirect boundary integral method to obtain the three‐dimensional response of an infinitely long, layered, viscoelastic valley of arbitrary cross‐section embedded in a layered viscoelastic half‐space is presented. The valley is excited by homogeneous plane waves impinging at an oblique angle with respect to the axis of the valley. The method and associated computer programs are tested by comparison with available results in the limiting two‐dimensional case of incidence normal to the axis of the valley. Additional comparisons with previous three‐dimensional results obtained by a hybrid finite element‐boundary integral method for cylindrical valleys subjected to obliquely incident waves show large differences. However, the results obtained here for an infinitely long valley appear to be in some agreement with earlier results for an elongated prolate semi‐ellipsoidal valley and with results obtained by a discrete wavenumber boundary element approach. An extensive bibliography on the dynamic response of valleys is also presented.
Implications of design philosophies for seismic response of steel moment frames
Authors: Osman Ashraf , Ghobarah A. , Korol R. M. 
Published: April 2007

AbstractDuring a severe earthquake, steel moment resisting frames are expected to experience significant inelastic deformation in their members and joints. This behaviour is dependent upon several design parameters such as member sizes, frame's overstrength, member deformation capacities and the detailing of components. In this study, the influence of such aspects on the inelastic response of frames is investigated. Inelastic static and dynamic analyses were performed on four frames of different designs for a typical six‐storey building. The frames were designed and detailed in accordance with current North American code requirements. The computed response of each frame was compared with the behaviour expected by the codes. Recommendations for a design procedure are suggested for improving the structural performance of low‐rise steel frames subjected to strong earthquake excitation.
Doubly asymptotic multi‐directional transmitting boundary for dynamic unbounded medium‐structure‐interaction analysis
Authors: Wolf John P. , Song Chongmin 
Published: April 2007

AbstractThe novel doubly asymptotic multi‐directional transmitting boundary combines the advantages of the doubly asymptotic and multi‐directional formulations. It is rigorous for the low‐frequency limit (static case) and the high‐frequency limit in the wave‐propagation direction perpendicular to the artificial boundary and at all the preselected angles corresponding to various apparent velocities. It is implemented straightforwardly in the finite‐element method. The doubly asymptotic multi‐directional transmitting boundary is temporally local and spatially either global or local depending on the implementation of the static‐stiffness matrix. It leads to much higher accuracy than other transmitting boundaries with the same finite‐element mesh.
Analysis of the failure of interstate 10 freeway ramp during the Northridge earthquake of 17 January 1994
Authors: Broderick B. M. , Elnashai A. S. 
Published: April 2007

AbstractThe response of a reinforced concrete freeway structure damaged during the Northridge earthquake is determined using non‐linear dynamic finite element analysis. The results obtained allow the ability of contemporary analysis techniques to predict the seismic response of such structures to be assessed and the critical aspects of the behaviour of the structure to be identified. Comparison is made with the response predicted using equivalent static analysis and more simplified dynamic analysis, from which the results of the more advanced analysis are shown to be superior. The influence of a number of modelling assumptions, principally with regard to boundary conditions, on the computed response is also assessed. From this, the disparity between the design conditions and those actually pertaining at the time of the earthquake are seen to play a crucial role in the mode of failure of the structure. It is concluded that, upon the development of an accurate structural model, the analytical results correlated well with the behaviour observed in post‐earthquake reconnaissance.
Simplified 3‐D dynamic analysis of structures with flexible diaphragms
Authors: Tena‐Colunga Arturo , Abrams Daniel P. 
Published: April 2007

AbstractA simplified method of 3‐D dynamic analysis, named 3‐D quasi‐dynamic analysis, is presented. This method has been primarily used to evaluate stress states at identified times of peak dynamic responses of structures with flexible diaphragms. The quasi‐dynamic analysis consists of extracting the accelerations predicted by the time‐step integration analyses of two 2‐D discrete MDOF dynamic models of a given structure (each discrete model corresponding to one of the principal orthogonal directions of the structure) at given times of interest. These accelerations are imposed on a 3‐D representation of the structure (for example, a finite element mesh) as equivalent static forces. Accelerations at the diaphragms are assumed to act over the same tributary areas of the diaphragms considered in the 2‐D discrete dynamic models.The study of the firehouse of Gilroy (an unreinforced masonry structure with flexible diaphragms) during the Loma Prieta Earthquake is presented to illustrate the 3‐D quasi‐dynamic seismic analysis. This method was compared to the more traditional 3‐D modal time‐step integration and 3‐D response spectra analyses. The quasi‐dynamic analysis had a general good agreement with the more formal, complex and computationally extensive modal time‐step integration analysis. The 3‐D response spectra analysis was very conservative and had a poor correlation with both the quasi‐dynamic and the modal time‐step integration analyses. The case study of the firehouse of Gilroy suggested that if 3‐D effects have to be considered in the evaluation of a given structure, the quasi‐dynamic analysis constitutes a reliable and computationally cheaper alternative to the more traditional methods of 3‐D dynamic analysis.
Tuned mass dampers for structures with closely spaced natural frequencies
Authors: Abé M. , Igusa T. 
Published: April 2007

AbstractAnalytical results are developed for vibration control of structures with one or more Tuned Mass Dampers (TMDs). The input is a harmonic load with a range of possible frequencies. The control objective is to reduce the maximum amplitude of the structural response. Perturbation theory is used with three sets of small parameters: the ratio of TMD and structural modal masses, the damping of the system, and the differences between the structural and loading frequencies. It is shown analytically that for structures with widely spaced natural frequencies, the response can be approximated accurately by the response of the well‐known single‐mode structure/TMD system. For structures with p closely spaced natural frequencies, more general analytical results are developed to describe the coupling between the motions of the p modes of the structure and the multiple TMDs. The results show that at least p TMDs with properly placed attachments to the structure are necessary to control the response. If fewer TMDs are used, the maximum frequency response has a lower bound which is independent of the properties of the TMDs. The TMD placement is shown to be always important, regardless of the spacing of the structure's natural frequencies. The results are illustrated for both lumped‐mass and continuous structures.
Efficient modal analysis for structures with soil‐structure interaction
Authors: Wu Wen‐Hwa , Smith H. Allison 
Published: April 2007

AbstractAn efficient methodology is presented which uses modal analysis implemented in the frequency domain to obtain the structural response of a system with soil‐structure interaction. The interaction effects are represented using a free‐field ground motion modification factor, derived for each mode of vibration and used in the determination of structural response. Applying this algorithm, the advantages of the modal superposition method are fully exploited, and the interaction problem can be solved easily and effectively within the framework of the conventional frequency domain analysis for a fixed‐base structure. In addition, this method produces accurate approximation with less computational effort due to consideration of only the first few vibration modes of the structure.
Effects of weathering on site response
Authors: Davis Rob 
Published: April 2007

AbstractNearly all studies of site response under seismic excitation employ idealized site models in which uniform layers of homogeneous soils are separated by perfect interfaces. The impedance mismatch at each interface gives rise to wave reflections which strongly affect the calculated free surface response. In reality, these perfect interfaces may often not exist. Instead, a zone in which materials from both above and below are mingled may form a blurred interface between layers. This article examines the effects of such weathered zones. The zone is modelled by a linearly varying shear modulus so that no abrupt impedance change occurs. Significant differences in response of weathered and unweathered profiles are found.
Investigation of non‐linear site amplification at two downhole strong ground motion arrays in Taiwan
Authors: Wen Kuo‐Liang , Beresnev Igor A. , Yeh Yeong Tein 
Published: April 2007

AbstractNon‐linear seismic response of soil is studied by comparing the spectral ratios of surface to downhole horizontal accelerations on weak and strong motion. Data from two boreholes are analysed. One is drilled in the alluvial deposits in the south–west quadrant of the SMART 1 array. The second one penetrates Pleistocene terrace deposits in the northern part of the SMART2 array. Observed weak and strong motion spectral ratios are compared with the theoretical ones predicted by the geotechnical soil model which postulates a hysteretic constitutive law. A significant non‐linear response is found at the first site for the events with surface peak acceleration exceeding roughly 0–15g. Deamplification of the strong motion occurred in the frequency range from approximately 1 to 10 Hz. The maximum observed difference between the average weak and strong motion amplification functions of an 11 m‐thick near‐surface stratum is a factor of 2–3. Nonlinear response characteristics are in qualitative agreement with the model. An additional corollary is that the amplification function calculated from the shear wave coda is equivalent to the average amplification calculated over the ensemble of small earthquakes. No statistically significant non‐linear response is detected on the second array, that is tentatively accounted for by the stiffer soil conditions and weaker accelerations achieved at the SMART2 site. The results indicate that the non‐linear amplification can be detectable at certain soil conditions above a threshold acceleration level.
Localized identification of MDOF structures in the frequency domain
Authors: Zhao Q. , Sawada T. , Hirao K. , Nariyuki Y. 
Published: April 2007

AbstractFor the identification of multi‐degree‐of‐freedom structures, it is not practical to identify all of the parameters included in the structures because enormous computation time is required and because identifiability may not be possible. In this paper, a localized identification approach through substructuring is formulated in the frequency domain. A technique of spectral smoothing is incorporated in the approach to deal with noise‐corrupted data. The proposed approach can be used to identify the structural parameters in any part of interest in a structure. The numerical investigations for a lumped mass‐spring‐dashpot system indicate that faster convergence and higher accuracy are achieved and the noise influences on the identified results are reduced greatly by spectral smoothing. The approach also applies to whole‐structure identification if the required records available and the numerical example shows that higher accuracy results are obtained with less cpu time and more poorly guessed initial values as compared with the general complete‐structure identification.