bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication of ordered Ta2O5 nanodots using an anodic aluminum oxide template on Si substrate
Authors: Yang Ching-Jung , Chen Chih , Wu Pu-Wei , Shieh Jia-Min , Wang Shun-Min , Liang Shih-Wei
Published: April 2007

Ordered arrays of Ta2O5 nanodots were prepared using anodic aluminum oxide (AAO) as a template to support localized oxidation of TaN. Films of TaN (50 nm) and Al (1.5 μm) were deposited successively on p-type Si wafers and followed by a two-step anodization process at 40 V using oxalic acid as the electrolyte. The first anodization promoted growth of irregular AAO from overlying Al film. After chemical etching, the second anodization was performed to develop well-organized AAO channels and initiate oxidation of underlying TaN film to form tantalum oxide nanodots at the AAO pore bottoms. X-ray photoelectron spectroscopy results confirmed the chemical nature of nanodots as stoichmetric Ta2O5. X-ray diffraction demonstrated the amorphous characteristic of Ta2O5. As shown in field-emission scanning electron microscopy and transmission electron results, the Ta2O5 nanodots exhibited a hillock structure 80 nm in diameter at the bottom and 50 nm in height. We also synthesized 30-nm nanodots by adjusting AAO formation electrochemistry. This demonstrates the general applicability of the AAO template method for nanodot synthesis from nitride to oxide at a desirable size.
The Emerging Role of Targeted Therapy for Hematologic Malignancies: Update on Bortezomib and Tipifarnib
Authors: Armand Jean-Pierre , Burnett Alan K. , Drach Johannes , Harousseau Jean-Luc , Löwenberg Bob , San Miguel Jesús
Published: April 2007

Learning Objectives

After completing this course, the reader will be able to: Discuss the role of bortezomib and tipifarnib in managing hematologic malignancies.Identify the molecular targets and mechanisms of action of bortezomib and tipifarnib.Describe the toxicities seen with bortezomib and tipifarnib.

CME Access and take the CME test online and receive 1 AMA PRA Category 1 Credit™ at CME.TheOncologist.com
Is Molecular Profiling Ready for Use in Clinical Decision Making?
Authors: Ioannidis John P. A.
Published: April 2007

Learning Objectives

After completing this course, the reader will be able to: Discuss the current status of translational research on molecular profiling for cancer.Highlight the steps and difficulties and biases involved in moving molecular profiling from the bench to the bedside.Propose potential solutions to the challenges of clinical use of this new technology.

CME Access and take the CME test online and receive 1 AMA PRA Category 1 Credit™ at CME.TheOncologist.com
Second-Generation Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors in Non-Small Cell Lung Cancer
Authors: Sequist Lecia V.
Published: April 2007

Learning Objectives

After completing this course, the reader will be able to: Describe the magnitude of benefit achieved through the use of first-generation EGFR TKIs in NSCLC.Discuss the clinical obstacles of primary and secondary resistance to first-generation EGFR TKI agents.Describe at least two strategies employed in improving the design of second-generation EGFR TKI agents over their predecessors.

CME Access and take the CME test online and receive 1 AMA PRA Category 1 Credit™ at CME.TheOncologist.com
Safe Administration of Iodine-131 Tositumomab After Repeated Infusion-Related Reactions to Rituximab
Authors: Hayslip John , Fenning Robert
Published: April 2007

Infusion-related reactions during administration of monoclonal antibody therapy are often mild and unlikely to recur with subsequent treatment. If patients experience another severe reaction upon reattempting treatment, future treatments with the same agent are typically not pursued. It is unclear whether different monoclonal antibodies that bind the same tumor cell or antigen are likely to induce similar infusion reactions. Here, we report the case of a patient with repeated severe infusion reactions with rituximab who subsequently safely received treatment with iodine-131 tositumomab and discuss the relevant literature.
Prognostic Factors and Risk-Based Therapy in Pediatric Acute Myeloid Leukemia
Authors: Meshinchi Soheil , Arceci Robert J.
Published: April 2007

Learning Objectives

After completing this course, the reader will be able to: Identify specific favorable and high-risk factors in pediatric AML.Discuss the rationale and indications for the use of stem cell transplantation in pediatric AML.Describe new technologies and emerging molecular prognostic markers in pediatric AML.

CME Access and take the CME test online and receive 1 AMA PRA Category 1 Credit™ at CME.TheOncologist.com
Evaluation of Two Preventive Interventions for Reducing Musculoskeletal Complaints in Operators of Video Display Terminals
Authors: Pillastrini Paolo , Mugnai Raffaele , Farneti Chiara , Bertozzi Lucia , Bonfiglioli Roberta , Curti Stefania , Mattioli Stefano , Violante Francesco Saverio
Published: April 2007

Background and Purpose

The purpose of this study was to evaluate the efficacy of a preventive ergonomic intervention, which was provided by physical therapists, on spinal and upper-extremity work-related posture and symptom complaints of workers who use video display terminals (VDT).

Subjects

Two hundred employees who spent at least 20 hours per week at a VDT were randomly divided into 2 groups. Group E received the ergonomic intervention and an informative brochure, and group I received only the brochure.

Methods

Both groups were evaluated at the beginning of the study and at a follow-up 5 months later. The following tools were used: a pain drawing and the Rapid Entire Body Assessment (REBA) method to assess spinal and upper-extremity work-related posture.

Results

Group E had a lower REBA score and reduced lower back, neck, and shoulder symptoms compared with group I.

Discussion and Conclusion

The results suggest that a personalized preventive ergonomic intervention can improve spinal and upper-extremity work-related posture and musculoskeletal symptoms for workers who use VDTs.
Synthesis of Monodisperse FeAu Nanoparticles with Tunable Magnetic and Optical Properties
Authors: Chiang I‐C. , Chen D.‐H.
Published: April 2007

Monodisperse FeAu nanoparticles can be synthesized via the reduction of gold acetate by 1,2‐hexadecanediol and the thermal decomposition of iron pentacarbonyl in the presence of the stabilizers oleic acid and oleylamine. The effects of composition, reaction time, and reaction temperature on their size, structure, and optical and magnetic properties are studied. It is found that the incorporation of Au into Fe nanoparticles leads to a structural change from body‐centered cubic (bcc) to face‐centered cubic (fcc). The size of the particles decreases with increasing reaction time and temperature because of atom rearrangement, and varies with the Au/Fe molar ratio as a result of the faster reduction rate of gold acetate compared with the decomposition rate of iron pentacarbonyl and the associated changes in nucleation and growth processes. The resultant FeAu nanoparticles possess the optical properties of Au nanoparticles and the magnetic properties of Fe nanoparticles. Their characteristic absorption bands, in the visible light range, become broader with decreasing Au/Fe molar ratio or increasing reaction time and temperature. Also, they are red‐shifted with decreasing the Au content and blue‐shifted with increasing reaction time. In addition, the particles are nearly superparamagnetic. With the increase in the Au/Fe molar ratio, their blocking temperature and coercivity increase while the saturation magnetization and remnant magnetization decrease. They can be self‐assembled into parallel stripes in the direction of an applied magnetic field.
Supramolecular Nanostructuring of Silver Surfaces via Self‐Assembly of [60]Fullerene and Porphyrin Modules
Authors: Bonifazi D. , Kiebele A. , Stöhr M. , Cheng F. , Jung T. , Diederich F. , Spillmann H.
Published: April 2007

Recent achievements in our laboratory toward the “bottom‐up” fabrication of addressable multicomponent molecular entities obtained by self‐assembly of C60 and porphyrins on Ag(100) and Ag(111) surfaces are described. Scanning tunneling microscopy (STM) studies on ad‐layers constituting monomeric and triply linked porphyrin modules showed that the molecules self‐organize into ordered supramolecular assemblies, the ordering of which is controlled by the porphyrin chemical structure, the metal substrate, and the surface coverage. Specifically, the successful preparation of unprecedented two‐dimensional porphyrin‐based assemblies featuring regular pores on Ag(111) surfaces has been achieved. Subsequent co‐deposition of C60 molecules on top of the porphyrin monolayers results in selective self‐organization into ordered molecular hybrid bilayers, the organization of which is driven by both fullerene coverage and porphyrin structure. In all‐ordered fullerene–porphyrin assemblies, the C60 guests organize, unusually, into long chains and/or two‐dimensional arrays. Furthermore, sublimation of C60 on top of the porous porphyrin network reveals the selective long‐range inclusion of the fullerene guests within the hosting cavities. The observed mode of the C60 self‐assembly originates from a delicate equilibrium between substrate–molecule and molecule–molecule interactions involving charge‐transfer processes and conformational reorganizations as a consequence of the structural adaptation of the fullerene–porphyrin bilayer.
A Rapid and Efficient Method to Deposit Gold Particles onto Catalyst Supports and Its Application for CO Oxidation at Low Temperatures
Authors: Zhong Z. , Lin J. , Teh S.‐P. , Teo J. , Dautzenberg F. M.
Published: April 2007

A rapid, simple, and efficient method for the preparation of highly dispersed supported Au catalysts has been developed. In the preparation, NaBH4 is used to reduce the Au precursor, lysine is employed to cap the formed Au colloids, and a short sonication time is applied to facilitate dispersion and deposition of the Au colloids onto the catalyst support, which has been mixed with the precursor beforehand. The end‐point pH value of the solution and the isoelectric points (IEPs) of the catalyst supports have an influence on the size of the Au particles and their deposition. The optimum value for the end‐point pH is 7.5–10.0, and the IEP should be 5–10. The amino acid capping agent is easily removed at the catalyst activation stage at 200 °C, and the Au particles are thermally stable against sintering, even at 500 °C for 3 h. It is also proven that the method is applicable to the preparation of supported Pt catalysts. The catalytic activity of the prepared Au catalysts for CO oxidation in the absence/presence of H2 is comparable to that of a Au catalyst prepared by the co‐precipitation (CP) method, and to that of the standard catalyst from the World Gold Council (WGC). X‐ray photoelectron spectroscopy (XPS) results show that only metallic Au exists in the catalysts before and after activation, and also after the catalysis reaction.
Effect of organic modifiers on dynamic and static nanomechanical properties and crystallinity of intercalated clay–polycaprolactam nanocomposites
Authors: Sikdar Debashis , Katti Dinesh , Katti Kalpana , Mohanty Bedabibhas
Published: April 2007

Polymer clay nanocomposites (PCN) of Polyamide6 and sodium montmorillonite are prepared using different organic modifiers (12‐aminolauric acid, n‐dodecylamine, and 1,12‐diaminododecane) to study effect of organic modifiers on structure and nanomechanical properties of PCN. Using X‐ray diffraction and differential scanning calorimetry, crystalline nature of PCNs are evaluated. Nanoscale viscoelastic properties of PCNs are evaluated using nanodynamic mechanical analyzer (NanoDMA). Nanoscale elastic modulus and hardness of PCNs are evaluated using nanoindenter. PCNs show enhancement in elastic modulus, storage modulus, loss modulus, and loss factor by maximum amount of 62.88%, 56.38%, 145.74%, and 71.43%, respectively, and decrease in percentage crystallinity by 16.52% compared to pure polymer. This result indicates that organic modifiers have effect on crystallinity and nanomechanical properties of PCN. To evaluate effect of clay loading on nanomechanical properties of PCN, PCN containing 12‐aminolauric acid is synthesized with different weight percent (3, 6, and 9% of weight of polymer) of organically modified montmorillonite (OMMT), which shows that nanomechanical properties of PCN improves with increase in clay loading. Our study reveals that change in crystallinity of polymer in PCN may have role in the enhancement of nanomechanical properties of PCNs in comparison to pristine polymer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
When consumption benefits precede costs: towards an understanding of ‘buy now, pay later’ transactions
Authors: Siemens Jennifer Christie
Published: April 2007

An experiment investigates a real‐money ‘buy now, pay later’ transaction, whereby subjects experienced a varied time‐delay between transaction benefits and costs. Individuals were more satisfied when transaction benefits and costs occurred temporally together. When a time‐delay was imposed, respondents preferred a short delay to a long delay. Transaction satisfaction was found to mediate the effect of time‐delay on behavioral intentions to complete the transaction again and perceived transaction fairness. Results suggest that a previously‐incurred transaction benefit becomes disassociated with its' transaction cost over time, causing the later transaction cost to be perceived as a greater loss at time of payment. The findings provide preliminary indication of the length of delay necessary for benefits to begin psychologically decaying. Implications for ‘buy now, pay later’ transactions and consumer satisfaction are discussed. Copyright © 2007 John Wiley & Sons, Ltd.
Genome‐scale analysis of Mannheimia succiniciproducens metabolism
Authors: Kim Tae Yong , Kim Hyun Uk , Park Jong Myoung , Song Hyohak , Kim Jin Sik , Lee Sang Yup
Published: April 2007

Mannheimia succiniciproducens MBEL55E isolated from bovine rumen is a capnophilic gram‐negative bacterium that efficiently produces succinic acid, an industrially important four carbon dicarboxylic acid. In order to design a metabolically engineered strain which is capable of producing succinic acid with high yield and productivity, it is essential to optimize the whole metabolism at the systems level. Consequently, in silico modeling and simulation of the genome‐scale metabolic network was employed for genome‐scale analysis and efficient design of metabolic engineering experiments. The genome‐scale metabolic network of M. succiniciproducens consisting of 686 reactions and 519 metabolites was constructed based on reannotation and validation experiments. With the reconstructed model, the network structure and key metabolic characteristics allowing highly efficient production of succinic acid were deciphered; these include strong PEP carboxylation, branched TCA cycle, relative weak pyruvate formation, the lack of glyoxylate shunt, and non‐PTS for glucose uptake. Constraints‐based flux analyses were then carried out under various environmental and genetic conditions to validate the genome‐scale metabolic model and to decipher the altered metabolic characteristics. Predictions based on constraints‐based flux analysis were mostly in excellent agreement with the experimental data. In silico knockout studies allowed prediction of new metabolic engineering strategies for the enhanced production of succinic acid. This genome‐scale in silico model can serve as a platform for the systematic prediction of physiological responses of M. succiniciproducens to various environmental and genetic perturbations and consequently for designing rational strategies for strain improvement. Biotechnol. Bioeng. 2007;97: 657–671. © 2007 Wiley Periodicals, Inc.
Molecular engineering of epoxide hydrolase and its application to asymmetric and enantioconvergent hydrolysis
Authors: Lee Eun Yeol , Shuler Michael L.
Published: April 2007

Safety and regulatory issues favor increasing use of enantiopure compounds in pharmaceuticals. Enantiopure epoxides and diols are valuable intermediates in organic synthesis for the production of optically active pharmaceuticals. Enantiopure epoxide can be prepared using epoxide hydrolase (EH)‐catalyzed asymmetric hydrolysis of its racemate. Enantioconvergent hydrolysis of racemic epoxides by EHs possessing complementary enantioselectivity and regioselectivity can lead to the formation of enantiopure vicinal diols with high yield. EHs are cofactor‐independent and easy‐to‐use catalysts. EHs will attract much attention as commercial biocatalysts for the preparation of enantiopure epoxides and diols. In this paper, recent progress in molecular engineering of EHs is reviewed. Some examples and prospects of asymmetric and enantioconvergent hydrolysis reactions are discussed as supplements to molecular engineering to improve EH performance. Biotechnol. Bioeng. 2007;98: 318–327. © 2007 Wiley Periodicals, Inc.
Augmenting Reed–Solomon coding with retransmission for error recovery in 3G video broadcasts
Authors: Kang Kyungtae , Cho Yongwoo , Shin Heonshik
Published: April 2007

The error‐prone nature of the radio channel is the major challenge in servicing video streams over cdma2000 broadcast networks. The MAC protocol for broadcast and multicast services (BCMCS) in cdma2000 specifies forward error correction using Reed–Solomon coding, which is effective in recovering from bursts of errors. However, its performance degrades significantly when channel conditions are bad, a frequent occurrence at the edge of the coverage area, reducing the availability of high‐speed broadcasts. We propose an error recovery scheme and a scheduling algorithm based on the use of slots saved by changing to a Reed–Solomon code with a lower parity overhead. Within the fixed transmission budget thus created, corrupted packets are retransmitted in a priority order determined by a utility function that is derived from the map of the error control block at each mobile, and which also considers the number of mobiles that did not receive each lost packet. Simulation results show the effectiveness of the proposed scheme in improving the quality of high‐data‐rate MPEG‐4 video streams over a range of channel conditions. Copyright © 2007 John Wiley & Sons, Ltd.
Customizing customization: A conceptual framework for interactive personalization
Authors: Miceli Gaetano Nino , Ricotta Francesco , Costabile Michele
Published: April 2007

Several scholars have proposed personalization models based on product variety breadth and the intensity of customer–firm interaction with a focus on marketing strategies ranging from basic product versioning to customerization and reverse marketing. However, some studies have shown that the explosion of product variety may generate information overload. Moreover, customers are highly heterogeneous in willingness and ability to interact with firms in personalization processes. This often results in consumer confusion and wasteful investments. To address this problem, we propose a conceptual framework of e-customer profiling for interactive personalization by distinguishing content (that is, expected customer benefits) and process (that is, expected degree of interaction) issues.The framework focuses on four general dimensions suggested by previous research as significant drivers of online customer heterogeneity: VALUE, KNOWLEDGE, ORIENTATION, and RELATIONSHIP QUALITY. We also present a preliminary test of the framework and derive directions for customer relationship management and future research.
Mature DC from skin and skin‐draining LN retain the ability to acquire and efficiently present targeted antigen
Authors: Henri Sandrine , Siret Carole , Machy Patrick , Kissenpfennig Adrien , Malissen Bernard , Leserman Lee
Published: April 2007

Skin‐draining LN contain several phenotypically distinguishable DC populations, which may be immature or mature. Mature DC are generally considered to have lost the capacity to acquire and present newly encountered Ag. Using antibody‐opsonized liposomes as Ag carriers, we show that mature DC purified from skin explants are able to efficiently capture liposomes, process Ag encapsulated within them and activate Ag‐specific CD4+ T cells. Explant DC from mice with Langerhans cells (LC) expressing the primate diphtheria toxin receptor that were exposed to diphtheria toxin in vivo presented Ag as well as explant DC from wild‐type mice, indicating that LC are not required and dermal DC are probably responsible for this presentation. We further show that all DC subtypes from LN that capture opsonized Ag are capable of cross‐presenting it to CD8+ T cells. Induction of additional maturation in vivo by LPS or treatment with double‐stranded RNA did not alter the Ag presentation capacity of the skin or LN DC subtypes. These results suggest that mature DC present in skin‐draining LN may play an important role in the induction of primary and/or secondary immune responses against Ag delivered to the LN that they take up by receptor‐mediated endocytosis.
Hereditary complement C7 deficiency in nine families: Subtotal C7 deficiency revisited
Authors: Rameix‐Welti Marie‐Anne , Régnier Catherine H. , Bienaimé Frank , Blouin Jacques , Schifferli Jurg , Fridman Wolf H. , Sautès‐Fridman Catherine , Frémeaux‐Bacchi Veronique
Published: April 2007

Deficiencies in terminal complement components, including the component C7, are uncommon and associated with an increased risk of recurrent systemic neisserial infection. A total of 22 molecular defects have been reported in the C7 gene with both complete (C7Q0) and subtotal (C7SD) C7 deficiencies. In this study we report the molecular basis of nine new cases of C7 deficiencies that were characterized by exon‐specific sequence analysis. Seven different C7 gene mutations were identified corresponding to small deletions (n=2), splice site changes (n=1) and single base pair substitutions leading to nonsense (n=1) or missense (n=3) mutations. Altogether, three changes of the C7 gene (G357R, R499S and 5′ splice donor site of intron 16) account for half of the molecular defects which emphasize that a restricted number of molecular abnormalities are involved in this deficiency. We identified two patients with combined C7Q0/C7SD(R499S) and established the C7SD(R499S) frequency at about 1% in normal Caucasian population. We demonstrated that C7(R499S) mutant protein is retained in the endoplasmic reticulum whereas the wild‐type C7 is located in the Golgi apparatus. Our results provide evidence that R499S represents a loss‐of‐function polymorphism of C7 due to a defective folding of the protein.
Seismic response of rotating machines
Authors: Suarez L. E. , Singh M. P. , Rohanimanesh M. S.
Published: April 2007

The equations of motion of a rotor finite element subjected to six components of base excitation are developed by applying variational principles. The equations contain speed dependent gyroscopic terms, base rotation dependent parametric terms and several forcing function terms which depend upon the linear accelerations, rotational accelerations and a combination of linear and rotational velocities. To evaluate the importance of various terms, seismic response characteristics of a rotating machine subjected to simulated base excitations are studied. It is observed that even for strong rotational inputs the parametric terms in the equation of motion can be ignored without affecting the response. The rotational input terms in the forcing function, however, are quite important and can be ignored only when they are not very strong. Since the problematic parametric terms can be ignored, one can use a generalied modal analysis approach.
Behaviour of near‐source vertical and horizontal response spectra at smart‐1 array, Taiwan
Authors: Niazi M. , Bozorgnia Y.
Published: April 2007

Over 700 accelerograms recorded from 12 earthquakes in northeast Taiwan have been analysed for investigating the behaviour of the vertical and horizontal peak and spectral ground motion in the near‐source region. Pseudo‐relative spectral velocities (PSV), at 5 per cent critical damping for 23 frequencies in the range of engineering interest have been subjected to non‐linear regression procedures in terms of magnitude and hypocentral distance. Predicted response spectra for several discrete distances and magnitudes are presented. The results show that the shape of response spectra for both vertical and horizontal components of ground motion is magnitude‐ as well as distance‐dependent.

The 2/3 ratio of vertical to horizontal ground motion, commonly used in engineering applications, appears unconservative in the very near field for high frequency ground motion. However, it falls below 1/2 at distances greater than 50 km. The same ratio for peak ground velocity (PGV) and peak ground displacement (PGD) tends to increase with distance—the latter at a faster rate.
Dynamic pile‐soil‐pile interaction. Part II: Lateral and seismic response
Authors: Makris Nicos , Gazetas George
Published: April 2007

A simplified three‐step procedure is proposed for estimating the dynamic interaction between two vertical piles, subjected either to lateral pile‐head loading or to vertically‐propagating seismic S‐waves. The starting point is the determination of the deflection profile of a solitary pile using any of the established methods available. Physically‐motivated approximations are then introduced for the wave field radiating from an oscillating pile and for the effect of this field on an adjacent pile. The procedure is applied in this paper to a flexible pile embedded in a homogeneous stratum. To obtain analytical closed‐form results for both pile‐head and seismic‐type loading pile‐soil and soil‐pile interaction are accounted for through a single dynamic Winkler model, with realistic frequency‐dependent ‘springs’ and ‘dashpots’. Final‐ and intermediate‐step results of the procedure compare favourably with those obtained using rigorous formulations for several pile group configurations. It is shown that, for a homogeneous stratum, pile‐to‐pile interaction effects are far more significant under head loading than under seismic excitation.
A shear design equation for ductile R/C members
Authors: Ichinose T.
Published: April 2007

A design equation is proposed to prevent shear failure after flexural inelastic deformation. This equation is based on the truss‐strut model. Inelastic hinge rotation is assumed to reduce the effective strength of concrete and to increase the inclination of truss action inside hinge regions. The proposed equation is confirmed on the basis of existing experimental data. This equation is accepted in the 1990 Japanese Design Guidelines.
Optimal hybrid control of structures under earthquake excitation
Authors: Tadjbakhsh Iradj G. , Rofooei Fayaz
Published: April 2007

Optimal control of base‐isolated and non‐base‐isolated buildings subjected to earthquake excitation is considered. The control force at any instant is determined on‐line through minimizing a quadratic time‐dependent performance index based on the total energy imparted to the structure and the control effect. This control algorithm is based upon the use of discrete actuators and sensors that exert the control force and monitor the response of the building. Having constant gain matrices makes this algorithm efficient and easy to implement. The effect of time delay on the efficiency of the algorithm is investigated. Comparisons have been made to demonstrate the effectiveness of the proposed method.
An investigation of earthquake induced pounding between adjacent buildings
Authors: Anagnostopoulos Stavros A. , Spiliopoulos Konstantinos V.
Published: April 2007

The response of adjacent buildings in city blocks to several strong earthquakes is analysed, taking into account the mutual collisions, or pounding, resulting from insufficient or non‐existing separation distances. The buildings are idealized as lumped‐mass, shear beam type, multi‐degree‐of‐freedom (MDOF) systems with bilinear force‐deformation characteristics and with bases supported on translational and rocking spring‐dashpots. Collisions between adjacent masses can occur at any level and are simulated by means of viscoelastic impact elements. Using five real earthquake motions the effects of the following factors are investigated: building configuration and relative size, seismic separation distance and impact element properties. It is found that pounding can cause high overstresses, mainly when the colliding buildings have significantly different heights, periods or masses. This suggests a possibility for introducing a set of conditions into the codes, combined with some special measures, as an alternative to the seismic separation requirement.
Empirical green's function corrected for source effect
Authors: Izutani Yasuo , Katagiri Fuyuki
Published: April 2007

One of the severe problems in the semi‐empirical method for the prediction of strong ground motions is that there is no objective criterion for choosing empirical Green's functions. It is undesirable that synthesized strong ground motions are affected by the source process of an earthquake whose record is adopted as an empirical Green's function. Through the analysis of strong motion accelerograms of two aftershocks of the 1983 Japan Sea earthquakes, it is found that characteristics of the accelerograms are dependent on the moment rate function derived from teleseismic observations. A procedure is presented for removing the effect of the source process from observed strong motion accelerograms. The thus obtained empirical Green's function expresses approximately the impulse response of the medium between the earthquake source and the observation site.
A new passive confinement model for the analysis of concrete structures subjected to cyclic and transient dynamic loading
Authors: Madas P. , Elnashai A. S.
Published: April 2007

The paper describes an analytical model for reinforced concrete members subjected to cyclic or transient dynamic loading. Model characterization is given in the context of a pseudo‐spatial description of the stress state. This comprises a procedure for calculating and continuously updating the transverse confinement stress for a given applied axial strain, thus accounting for the passive confinement which an element of concrete is subjected to within a structural member. Comparison with existing uniaxial models shows that the new formulation takes note of previously neglected effects, such as non‐coincident peaks of the steel and concrete stress‐strain curves, and Poisson's ratio variation during loading. Moreover, comparison with 3D concrete constitutive relationships indicates that the level of accuracy is comparable, whilst significant computing time saving is achieved by the new model. Model validation is confirmed by comparison with cyclic loading laboratory test results. Finally, two frames with the same overall strength enhancement factor are analysed under earthquake loading; the difference in the response clearly demonstrates that the model accounts for important behavioural characteristics which are hitherto neglected in comparable existing models.
A posteriori local error estimation and adaptive time‐stepping for newmark integration in dynamic analysis
Authors: Zeng L. F. , Wiberg N.‐E. , Li X. D. , Xie Y. M.
Published: April 2007

A simple a posteriori local error estimate for Newmark time integration schemes in dynamic analysis is presented, based on the concept of a so called ‘post‐processing’ technique. In conjunction with the error estimate, an adaptive time‐stepping algorithm is described, which adjusts the time step size so that the local error of each time step is within a prescribed error tolerance. Numerical examples given in the paper indicate that the error estimate is asymptotically convergent, computationally efficient and convenient, and the adaptive time‐stepping scheme can predict a nearly optimal step size from time to time, thus making the numerical solution reliable in an efficient manner.
Spring‐viscous damper systems for combined seismic and vibration isolation
Authors: Makris N. , Constantinou M. C.
Published: April 2007

The coupled lateral‐vertical‐rocking dynamic response of spring‐viscous damper isolated structures is considered. The force‐displacement relation of the viscous dampers is described by an experimentally calibrated fractional derivative viscoelasticity model. The equations of motion are derived and reduced to a form for direct solution by the discrete Fourier transform method. The validity and accuracy of the derived solution are demonstrated by comparison with shake table test results.

The developed analysis procedure is employed in the seismic analysis of a recently constructed isolated structure. The analytical and experimental results demonstrate that spring‐viscous damper isolation systems are capable of providing both effective seismic and vibration isolation.
An identification methodology for a class of hysteretic structures
Authors: Peng C.‐Y. , Iwan W. D.
Published: April 2007

This paper presents a method of identification for determining non‐linear dynamic models for certain hysteretic structures. Particular attention is given to modelling and identifying the hysteretic behaviour of structures from strong‐motion earthquake data. In this method, the response is separated into mode‐like components which are analogous to those of a linear system. Based on modelling of the generalized restoring force of each mode‐like component, both non‐hysteretic and hysteretic non‐linear models are incorporated into the general methodology. A non‐hysteretic model provides an initial estimate for a final hysteretic model. The approach is applicable even when data are available from only a small number of locations in the structure. The structural model identified from this method provides a means to predict the response to future events and, ultimately, to examine the damage to a structure as a result of an earthquake.
Dynamics of pounding when two buildings collide
Authors: Maison Bruce F. , Kasai Kazuhiko
Published: April 2007

A formulation and solution of the multiple‐degree‐of‐freedom equations of motion for pounding between two multistorey buildings are presented. Pounding occurs at rigid horizontal diaphragms in each building. The theory is implemented into a microcomputer program and sample earthquake analyses involving pounding between 15‐storey and 8‐storey buildings are performed. The influence of building separation, relative mass, and contact location properties are assessed. Conclusions are drawn regarding response behaviour trends that are relevant to other actual pounding situations.
An efficient time‐domain soil‐structure interaction analysis based on the dynamic stiffness of an unbounded soil
Authors: Hayashi Yasuhiro , Takahashi Ikuo
Published: April 2007

An approximate method and a rigorous method are presented for the time‐domain soil‐structure interaction analysis, both of which use the stiffness of soil obtained numerically or experimentally in the limited frequency range. In the aseismic design of a large‐scale structure, the approximate and rigorous methods are intended to be used in a preliminary analysis and a detailed study, respectively. Both methods are based on the approximation that the first few terms of the Fourier or Taylor expansions of a frequency‐dependent function are used. The difference lies in the number of coefficients of each series, and also in the manner in which the coefficients can be determined. In order to demonstrate the validity of the proposed methods, a soil‐structure system, whose soil has a complex profile under the foundation, is analysed. The dynamic stiffness of the soil is calculated by a 3‐D hybrid approach that combines the finite element method and the boundary element method. As a result, the present methods are capable of evaluating the complexity of the soil more precisely and efficiently than conventional methods.
Lumped‐parameter model for a rigid cylindrical foundation embedded in a soil layer on rigid rock
Authors: Wolf John P. , Paronesso Antonio
Published: April 2007

To represent a cylindrical rigid foundation vibrating in horizontal, vertical, rocking or torsional motions embedded in a soil layer resting on rigid rock, a lumped‐parameter model is described. The coupling between the horizontal and rocking degrees of freedom is considered. For each degree of freedom eight frequency‐independent real coefficients determine the springs, dashpots and the mass of the lumped‐parameter model with two internal degrees of freedom. These coefficients are specified for various ratios of the radius of the foundation to the depth of the layer and lateral contact ratios. To derive the mechanical properties of the lumped‐parameter model a systematic procedure of curvefitting of the dynamic‐stiffness coefficient up to, in general, twice the fundamental frequency of the layer is applied, capturing the fact that below the (horizontal) fundamental frequency (cutoff frequency) no radiation of energy occurs. The lumped‐parameter model can be used to represent the soil in a standard finite‐element program for structural dynamics working in the time domain, whereby the structure can exhibit non‐linear behaviour. Stability of the unbounded soil‐layer model and of the total system is guaranteed. A hammer foundation with partial uplift of the anvil is analysed for illustration.
Fundamental characteristics of Multiple Tuned Mass Dampers for suppressing harmonically forced oscillations
Authors: Yamaguchi Hiroki , Harnpornchai Napat
Published: April 2007

Multiple Tuned Mass Dampers (MTMD's) consisting of many tuned mass dampers (TMD's) with distributed natural frequencies are considered for suppressing effectively the harmonically forced single mode response of structures. The fundamental characteristics of MTMD's are investigated analytically with the parameters of the covering frequency range of MTMD's, the damping ratio of each TMD and the total number of TMD's. The effectiveness and the robustness of MTMD's are also discussed in comparison with those of the usual single TMD. It is found that there exists an optimum MTMD for the given total number of TMD's with the optimum frequency range and the optimum damping ratio and that the optimum MTMD is more effective than the optimum single TMD. As for the robustness, it is also clarified that a MTMD can be much more robust than a single TMD while keeping the same level of effectiveness as the optimum single TMD.
Partial eigensolution of damped structural systems by Arnoldi's method
Authors: Chen Harn C.
Published: April 2007

An efficient numerical algorithm is developed to solve the quadratic eigenvalue problems arising in the dynamic analysis of damped structural systems. The algorithm can even be applied to structural systems with non‐symmetric matrices. The algorithm is based on the use of Arnoldi's method to generate a Krylov subspace of trial vectors, which is then used to reduce a large eigenvalue problem to a much smaller one. The reduced eigenvalue problem is solved and the solutions are used to construct approximate solutions to the original large system. In the process, the algorithm takes full advantage of the sparseness and symmetry of the system matrices and requires no complex arithmetic, therefore, making it very economical for use in solving large problems. The numerical results from test examples are presented to demonstrate that a large fraction of the approximate solutions calculated are very accurate, indicating that the algorithm is highly effective for extracting a number of vibration modes for a large dynamic system, whether it is lightly or heavily damped.
An experimental study on active tendon control of cable‐stayed bridges
Authors: Warnitchai Pennung , Fujino Yozo , Pacheco Benito M. , Agret Remi
Published: April 2007

Active tendon control of cable‐stayed bridges subject to a vertical sinusoidal force is experimentally and analytically studied. Emphasis is placed on the effects of linear and non‐linear internal resonances on the control (due to the presence of the cable vibration). A simple cable‐supported cantilever beam is used as a model. It is found that active tendon control is very effective in vertical girder motion with small cable vibration (girder dominated motion), whereas it is not effective in vertical girder motion with large cable vibration (cable dominated motion). Analytical prediction is very satisfactory except for the latter case.
Seismic response of light equipment in torsional buildings
Authors: Yang Yeong‐Bin , Huang Wei‐Hsi
Published: April 2007

This paper attempts to study the response of light equipment items attached to a multi‐storey building that may be subjected to large torsional deformations during the earthquake excitation. To account for the effect of torsion and translation, each storey of the building is modelled as two degrees of freedom (DOFs), with one DOF for translation and the other for torsion. Perturbation techniques are employed to find closed‐form expressions for the modal properties of the combined system in terms of the properties of the individual subsystems. The interaction between the equipment and building is studied for both tuned and detuned modes of vibration. Modal synthesis results obtained using the present technique based on the complete quadratic combination (CQC) method are compared with solutions obtained by other methods.
An efficient, adaptive algorithm for large‐scale random vibration analysis
Authors: Harichandran Ronald S.
Published: April 2007

An efficient, adaptive and robust algorithm is proposed to reduce the cost of large‐scale stationary and transient random vibration analysis of structures excited by multiple partially correlated nodal and or base excitations. The cost saving is accomplished by computing integrals selectively, and yet attempting to maintain a level of accuracy desired by the analyst. Recently, proposed closed‐form solutions for fully coherent propagating band‐limited white‐noise excitation are used to rank approximately the terms in the modal covariance matrix. Terms are then evaluated starting from the most important one, and the computations are terminated in such a way that the accuracy level requested by the user is satisfied in an approximate sense. Two variations of the algorithm are proposed: the first one is more robust and is preferred, and is recommended when computing a relatively small number (hundreds) of response quantities; the second one is more efficient when computing a very large number (thousands) of response quantities. Both variations are adaptive, and consider the closeness, damping and participation of all modes explicitly, while the first method also considers the mode shapes. The efficiency and accuracy of the algorithm is investigated by using it to compute the stationary and transient seismic response of the Golden Gate suspension bridge.
Experimental assessment of low‐aspect‐ratio, reinforced concrete shear wall stiffness
Authors: Farrar Charles R. , Baker William E.
Published: April 2007

Low‐aspect‐ratio, reinforced concrete shear walls are the primary lateral‐load‐carrying element in many structures designed for protective purposes. A review of the technical literature shows that considerable uncertainty exists regarding the elastic stiffness these structures will exhibit during seismic excitation. Because of this uncertainty, current design practice often employs a stiffness reduction factor. In an attempt to develop accurate information regarding the stiffness of these structures, 13 shear wall elements were tested statically; dynamically, with simulated seismic base excitations on a shake table; and with experimental modal analysis procedures. Results of these tests show that the shear wall's stiffness can be accurately estimated with a mechanics‐of‐materials analysis that accounts for shear deformation.
Symmetric modes of vibration for A circular plate using finite dynamic elements
Authors: Fergusson N. J. , Pilkey W. D.
Published: April 2007

The dynamic element method has been shown previously to provide a computational advantage over the ordinary finite element method for various beam elements. The Taylor expansions are computed here for the dynamic shape functions (two terms) and dynamic stiffness matrix (four terms) for the axisymmetric vibrations of an annular plate element. The complicated matrices which result are made more tractable by expressing them as power series in powers of the aspect ratio. The percentage error in the natural frequencies is then calculated using both the two‐ and the three‐term dynamic stiffness matrix, demonstrating the increased accuracy for a given number of elements.
Influence of time‐domain dam–reservoir interaction on cracking of concrete gravity DAMS
Authors: Wepf Dieter H. , Feltrin Glauco , Bachmann Hugo
Published: April 2007

Based on a non‐linear dam‐reservoir interaction model, a study investigating the earthquake response of concrete gravity dams is presented. For the propagation of cracks in unreinforced mass concrete, a discrete crack approach formulation based on the finite element method is applied. A special crack element is used to follow a fictitious crack in order to account for a zone of microcracks developing at the crack tip. The reservoir is modelled using the boundary element method. At a fictitious boundary dividing the irregular finite part of the reservoir from the regular infinite part, the loss of energy due to pressure waves moving away towards infinity is taken into account rigorously. Analyses are performed on the tallest non‐overflow monolith of the Pine Flat Dam located in Kern County, California. The interaction of a dam, which may exhibit cracks in mass concrete, with a reservoir domain of arbitrary geometry extending to infinity is studied. Some main parameters are investigated. The importance of tools capable of handling the non‐linear dam‐reservoir interaction is emphasized.
Parametric study of vertical vibrations of circular flexible foundations on layered media
Authors: Gucunski Nenad , Peek Ralf
Published: April 2007

The paper presents results of a parametric study of vertical oscillations of a flexible circular plate on the surface of an elastic half‐space and an elastic layered system. The solution of the problem is based on the ‘ring method’. Vertical oscillations have been analysed to determine the displacement and soil reaction distributions at the soil‐plate interface and the impedance functions. Parameters of the study include material and geometrical properties of a soil system and a plate and the load distribution on the plate. The results indicate significantly different behaviour of a flexible plate from that of a rigid one. Based on the observed behaviour, a classification of plates has been suggested.
Seismic response controlled structure with Active Variable Stiffness system
Authors: Kobori Takuji , Takahashi Motoichi , Nasu Tadashi , Niwa Naoki , Ogasawara Katsura
Published: April 2007

The Active Variable Stiffness (AVS) system is proposed as a seismic response control system. It actively controls structural characteristics, such as stiffness of a building, to establish a non‐resonant state against earthquake excitations, thus suppressing the building's response. It consumes a relatively small amount of energy and maintains the safety of the building in moderate to severe earthquakes. In order to accumulate practical data and investigate them, a building has been constructed as a trial. This paper describes the applied system, the control algorithm, verification of stiffness selection, results of tests for verifying system characteristics, some observed earthquake records and simulation analyses. Responses in controlled and uncontrolled states have been compared to show the effectiveness of the proposed system.