bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural variation manipulates the differential oxidative susceptibility and conformational stability of apolipoprotein E isoforms
Authors: Su Kuo‐Liang , Wen Ta‐Hsiang , Chou Chi‐Yuan , Chang Gu‐Gang , Liu Guang‐Yaw , Hung Hui‐Chih
Published: April 2007

A growing amount of evidence implicates the involvement of apolipoprotein E (apoE) in the development of late‐onset and sporadic forms of Alzheimer's disease (AD). It is now generally believed that the ε4 allele is associated with AD and the oxidative stress is more pronounced in AD. However, only limited data are available on apoE isoform‐specificity and its relationship to both the oxidative susceptibility and conformational stability of apoE. In this article, we use site‐directed mutagenesis to investigate the structural role of amino acid residue 112, which is the only differing residue between apoE3 and E4. We examine the structural variation manipulating the oxidative susceptibility and conformational stability of apolipoprotein E isoforms. Arg112 in apoE4 was changed to Ala and Glu. Previous research has reported that apoE4 is more susceptible to free radicals than apoE3. In protein oxidation experiments, apoE4‐R112A becomes more resistant to free radicals to the same extent as apoE3. In contrast, apoE4‐R112E becomes the most susceptible protein to free radicals among all the apoE proteins. We also examine the conformational stability and the quaternary structural change by fluorescence spectroscopy and analytical ultracentrifugation, respectively. ApoE3 and E4 show apparent three‐ and two‐state unfolding patterns, respectively. ApoE4‐R112A, similar to apoE3, demonstrates a biphasic denaturation with an intermediate that appears. The denaturation curve for apoE4‐R112E, however, also displays a biphasic profile but with a slight shoulder at ∼1.5M GdmCl, implying that an unstable intermediate existed in the denaturation equilibrium. The size distribution of apoE isoforms display similar patterns. ApoE4‐R112E, however, has a greater tendency to dissociate from high‐molecular‐weight species to tetramers. These experimental data suggest that the amino acid residue 112 governs the differences in salt‐bridges between these two isoforms and thus has a significant impact on the free radical susceptibility and structural variation of the apoE isoforms. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Simulation and measurement of the self‐heating in GaN HFETs
Authors: McAlister S. P.
Published: April 2007

Self‐heating in a GaN HFET has been simulated and used to deduce different average or effective temperatures, which are representative of the device performance. This suggests how simple electrical measurements, coupled with simulation may help reveal the maximum temperatures in a device. Some experimental data is shown indicating how electrical measurements by themselves can be used to do this. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamic drift‐diffusion simulation of InP/InGaAs SAGCM APD
Authors: Xiao Y. G. , Li Z. Q. , Li Z. M. Simon
Published: April 2007

In this work, based on the advanced drift and diffusion model with commercial software, the Crosslight APSYS, InP/InGaAs separate absorption, grading, charge and multiplication APDs for high bit‐rate operation have been modeled. Basic physical quantities such as band diagram, optical absorption and generation are calculated. Performance characteristics such as dark‐ and photo‐current, photoresponsivity, multiplication gain, breakdown voltage, excess noise, frequency response and bandwidth etc., are simulated. The modeling results are selectively presented, analyzed, and some results are compared with experiments. Device design optimization issues are further discussed with respect to the applicable features of the Crosslight APSYS within the framework of the drift‐diffusion theory. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Improved InP‐based double heterojunction bipolar transistors
Authors: Lin Y. S. , Huang J. H. , Ho C. H.
Published: April 2007

This article develops two double heterostructure bipolar transistors (DHBTs) made by low‐pressure metamorphic organic chemical vapor deposition (LP‐MOCVD). One is a control DHBT with an abrupt base‐collector heterojunction (abrupt DHBT) and the other is an improved DHBT with a composite‐collector design (composite DHBT). Of the devices with no ledge passivation, the composite DHBT has a high common‐emitter current gain, a low offset voltage and voltage‐independent collector current characteristics, unlike the abrupt DHBT. The favorable performance of the composite DHBT follows mainly from the optimal collector design, which effectively lowers the potential spike at the base‐collector heterojunction. Furthermore, measurements of the composite DHBT with and without n‐InP emitter ledges are made. The composite DHBT with emitter ledges has a current gain of 180, which is 44% higher than that of the device with no emitter ledge. The higher current gain is attributable to the lower base surface recombination current in the composite DHBT with a ledge. The effectiveness of the composite‐collector design and the emitter ledge process of the presented DHBT is proven. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
GaN films deposited on (111)Si by CS‐MBD with re‐evaporation enhancement technique for UV light‐emitting devices
Authors: Arai Masatoshi , Sugimoto Koichi , Egawa Shinichi , Baba Taichi , Honda Tohru
Published: April 2007

GaN films were deposited at low temperature by compound‐source molecular beam deposition (CS‐MBD) with re‐evaporation enhancement (REE) technique. As the interval time of the pulsed‐source feeding during the GaN deposition was increased, the amount of the excess Ga in the deposited films was decreased. Cathodoluminescence (CL) intensity was improved with the decrease in the amount of excess Ga in the deposited films. The amount of excess Ga in the deposited films decreased after using REE technique. Using REE technique, GaN‐based thin‐film electroluminescent devices (TF‐ELDs) were fabricated. Near‐ultraviolet (UV) light emission, whose peak wavelength was located at 390 nm, was observed from the devices. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High frequency modulation effects on the relative intensity noise properties of 405 nm InAlGaN laser diodes
Authors: Yi Jong Chang , Cho Hyung Uk
Published: April 2007

The high frequency modulation effects on the relative intensity noise (RIN) characteristics of 405 nm InAlGaN laser diodes have been investigated taking into account the strain and thermal effects on the laser diode itself as well as external optical feedback effects. The simulation results indicate that the critical external optical feedback for –125 dB/Hz RIN is around 0.1%, a typical order found in practical DVD operating environments.By optimizing the injection current levels and its frequency, one can reduce the RIN with 0.1∼1% external feedback effect by more than 15 dB/Hz. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigations of InSb‐based quantum dots grown by molecular‐beam epitaxy
Authors: Deguffroy N. , Tasco V. , Baranov A. N. , Satpati B. , Trampert A. , Dunaevski M. , Titkov A. , Genty F. , Tournié E.
Published: April 2007

InSb quantum dots (QDs) have been grown by molecular‐beam epitaxy (MBE) on GaSb substrates. Typical MBE growth conditions lead to a low density (∼109 cm–2) of large islands which are dislocated. Insertion of a thin InAs nucleation layer increases the QDs density by one order of magnitude which is interpreted in terms of differing In‐to‐group‐V binding energies. Finally, we show that a high density (∼7 x 1010 cm–2) of small coherent QDs can be grown by using a two‐steps procedure. Photoluminescence near 3.5 µm is demonstrated. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Barrier‐ and in‐well pumped GaSb‐based 2.3 µm VECSELs
Authors: Wagner J. , Schulz N. , Rattunde M. , Ritzenthaler C. , Manz C. , Wild C. , Köhler K.
Published: April 2007

We report on recent advances in the performance of GaSb‐based optically‐pumped vertical‐external‐cavity surface‐emitting lasers (VECSELs) emitting at wavelengths around 2.3 µm. Both barrier and in‐well pumped VECSELs have been fabricated and analysed. Both variants incorporate a diamond intra‐cavity heat spreader as an efficient means for heat extraction from the active region. For barrier‐pumping, a maximum output power of 1.5 W with a beam propagation factor of M2 ≤ 3 has been achieved at a heat sink temperature of –20°C. Using in‐well pumping at 1.96 µm, the efficiency could be more than doubled, compared to barrier pumping, due to the significantly reduced quantum deficit, yielding a slope efficiency of 31% at a heat sink temperature of 10°C. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural characterization of MgO/c‐Al2O3 interfaces
Authors: Minegishi T. , Hanada T. , Suzuki H. , Vashaei Z. , Oh D. C. , Sumitani K. , Sakata O. , Cho M. W. , Yao T.
Published: April 2007

We have found that MgO deposited on c‐Al2O3 substrates at high temperatures formed MgAl2O4 by interdiffusion during MgO layer growth. The formation of spinel MgAl2O4 has been confirmed by in‐situ reflection high energy electron diffraction (RHEED) and grazing incident X‐ray diffracition (GIXD). The critical temperature (TC) for the formation of MgAl2O4 was found to be around 700 °C above which MgAl2O4 is formed at the MgO/c‐Al2O3 interface. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ultrafast nonlinear optical response of weakly confined excitons in GaAs thin films
Authors: Kojima O. , Isu T. , Ishi‐Hayase J. , Sasaki M. , Tsuchiya M.
Published: April 2007

We report on an ultrafast nonlinear optical response of weakly confined excitons in GaAs thin films observed by a two‐beam degenerate four‐wave‐mixing (DFWM) technique. An ultrafast optical response comparable to the pulse width appears under ultrashort‐pulse‐laser excitation condition. We clarified from the DFWM spectra that the plural exciton states contribute to the ultrafast response. The results imply a possibility of ultrafast switching devices using weakly confined excitons. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electroabsorption modulators on waveguide micro‐ring cavity resonators with self‐aligned total internal reflectors
Authors: Yi Jong Chang , Kim Doo Gun , Chung Youngchul , Dagli Nadir
Published: April 2007

The switching characteristics of an electroabsorption modulator fabricated on a waveguide‐coupled micro‐ring‐cavity resonator were investigated. The ring cavity resonator consists of ridge waveguide regions, total internal reflector mirrors, and a coupling region. The coupling region is implemented with a multimode interferometer (MMI) waveguide to enhance the coupling coefficient. The total internal reflection mirrors were fabricated by self‐aligned RIBE process resulting in minimal insertion losses of around 0.7 dB/mirror. The gain medium was a 1.55 μm InGaAsP MQW ridge waveguide, and the passive waveguide was a re‐grown 1.4 μm InGaAsP ridge structure. The sharp variation of the optical transmission through the micro‐ring‐cavity resonator near the resonance wavelength was utilized to realize efficient semiconductor optical modulators with a high extinction ratio. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Enhancement mode high mobility n‐MOSFET on gallium arsenide substrate
Authors: Rajagopalan K. , Abrokwah J. , Droopad R. , Passlack M.
Published: April 2007

MOS heterostructures grown by molecular beam epitaxy on III‐V substrates, employing a high‐κ dielectric stack (κ ≈ 20) comprising of gallium oxide and gadolinium gallium oxide have been fabricated. Mobilities exceeding 12,000 and 6,000 cm2/Vs, for sheet carrier concentration ns of about 2.5x1012 cm–2 were measured from InP and GaAs based MOSFET structures, respectively. These structures were designed for enhancement mode operation and include a 10 nm thick strained InxGa1–xAs channel layer with In mole fraction x of 0.3 and 0.75 on GaAs and InP substrates, respectively. NMOSFETs with a gate length of 1 μm and a source‐drain spacing of 3 μm were fabricated. These devices show a threshold voltage of 0.11 V. The saturation current, transconductance and on‐resistance were measured to be 380 mA/mm, 250 mS/mm, 4.5 Ω‐mm. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of ruthenium originating from the investigational anti‐cancer drug NAMI‐A in human plasma ultrafiltrate, plasma, and urine by inductively coupled plasma mass spectrometry
Authors: Brouwers Elke E. M. , Tibben Matthijs M. , Rosing Hilde , Schellens Jan H. M. , Beijnen Jos H.
Published: April 2007

We present a highly sensitive, rapid method for the determination of ruthenium originating from the investigational anti‐cancer drug NAMI‐A in human plasma ultrafiltrate, plasma, and urine. The method is based on the quantification of ruthenium by inductively coupled plasma mass spectrometry and allows quantification of 30 ng L−1 ruthenium in plasma ultrafiltrate and urine, and 75 ng L−1 ruthenium in human plasma, in 150 µL of matrix. The sample pretreatment procedure is straightforward and only involves dilution with appropriate diluents. The performance of the method, in terms of accuracy and precision, fulfilled the most recent FDA guidelines for bioanalytical method validation. Validated ranges of quantification were 30.0 to 1 × 104 ng L−1 for ruthenium in plasma ultrafiltrate and urine and 75.0 to 1 × 104 ng L−1 for ruthenium in plasma. The applicability of the method and its superiority to atomic‐absorption spectrometry were demonstrated in two patients who were treated with intravenous NAMI‐A in a phase I trial. The assay is now successfully used to support pharmacokinetic studies in cancer patients treated with NAMI‐A. Copyright © 2007 John Wiley & Sons, Ltd.
Mutual antagonism of SoxB1 and canonical Wnt signaling in sea urchin embryos
Authors: Angerer Lynne M. , Kenny Alan P. , Newman Laurel A. , Angerer Robert C.
Published: April 2007

Early development of animal embryos involves establishing axial polarities that specify the anlage of major tissues in a 3‐dimensional pattern. Cell fates are specified on this coordinate system through a combination of differential inheritance of maternal regulatory molecules and signaling interactions among cells. Correct patterning of cell fates along the primary axis of the sea urchin embryo depends on tightly regulating the ratio of activities of two nuclear regulatory proteins, SoxB1 and nuclear β–catenin. The latter acts at the top of the gene regulatory network that specifies mesoderm and endoderm and activates, directly or indirectly, signaling by Delta, Wnt8 and Nodal. In contrast, SoxB1 initially accumulates in all nuclei but is progressively eliminated from presumptive mesoderm and endoderm by β‐catenin‐dependent transcriptional repression and by localized protein turnover, a novel pathway acting downstream of canonical Wnt signaling. A precise temporal program for SoxB1 down regulation is crucial for endomesoderm development because SoxB1 interferes with β–catenin's transcriptional regulatory function. The mechanisms we are beginning to understand that govern the β–catenin‐SoxB1 antagonism in sea urchin embryos are likely to have broad significance, since Sox factors are involved in regulating many developmental processes in many deuterostome embryos.
Secondary axis specification in sea urchin embryos
Authors: Bradham Cynthia A. , McClay David R.
Published: April 2007

Secondary axis specification is a process that relies on asymmetric nuclearization of transcription factors in flies and vertebrates, such that the crucial factor is nuclear and therefore functional only in cells along one side of the embryo. In vertebrates, this transcription factor is β‐catenin, which is canonically activated downstream from Wnt signals. However, the sea urchin uses asymmetric β‐catenin nuclearization during specification of the primary animal‐vegetal axis, rather than the secondary oral‐aboral (OA) axis. OA specification relies instead on the asymmetric localization of p38 MAPK, a signaling kinase that directly modulates transcription factor activity. A number of genes are expressed in the oral territory downstream from p38, including Nodal and Goosecoid, both of which are associated with secondary axis specification in vertebrate embryos. Because the p38 asymmetry is the earliest known event in the specification of the OA axis, an outstanding question concerns identifying the apparatus upstream from p38 that regulates its asymmetrical activity. Intriguingly, this may be controlled by reactive oxygen species released from the mitochondria, which are asymmetrically distributed about the OA axis.
The many faces of egg activation at fertilization
Authors: Leguia Mariana , Wessel Gary M.
Published: April 2007

The signaling networks controlling calcium release and cortical granule exocytosis at fertilization are complex and multilayered, providing various points for regulatory input and quality control. Though it is clear that many of the mechanisms leading to both calcium release and cortical granule exocytosis are conserved, a great deal of variability exists between homologous signaling pathways in different species. The signaling pathways responsible for the release of calcium seen at fertilization vary from species to species, yet they center around the importance of IP3‐mediated signaling. Similarly, while there are differences in the mechanisms of regulated secretion between species and between intracellular membrane trafficking events, particularly with respect to time and space, all seem to be dependent on the SNARE proteins and their regulator and effector proteins. What has been most helpful in these studies is the convergence of studies from many different species of eggs. With the amazing divergence of reproductive processes and mechanisms that exists throughout phylogeny, it is comforting to see such strong overlapping roles of key players in widely disparate eggs.
Recent structural applications of active control technology
Authors: Soong T. T. , Reinhorn A. M. , Aizawa S. , Higashino M.
Published: April 2007

A number of active control systems have been developed, fabricated and installed in full‐scale structures and they have been subjected to actual wind forces and ground motions. The focus of this paper is on the observed response of several of these systems. They include an active bracing system and an active mass damper system installed in a six‐story experimental building, and two hybrid mass damper systems installed in two actual buildings. The configurations of these systems are summarized together with their performance characteristics. Observed performance of these systems during actual wind storms and moderate earthquakes shows that they meet their basic design objectives. Furthermore, their performance can be adequately predicted through simplified analytical and simulation procedures.
An optimal design procedure for delayed control of linear structures
Authors: Baratta A. , Papa F , Zuccaro G.
Published: April 2007

The purpose of the paper is to investigate the problem of the delayed active control of a linear system controlled by a closed‐loop linear law under the action of external dynamic forces. The choice of the optimal parameters, for each assigned delay, is pursued through the optimization of the controlled response with the constraint of limiting the control force under a prefixed threshold. The behaviour of the response, varying the control parameters, is investigated through the mapping of the “solution in the norm” of the response rather than the definition of the punctual response of the system.

Numerical applications for different values of the delay are performed for a SDOF structure showing the range of the feasibility of the closed‐loop linear approach on one side, and proving the critical role of the delay on the other side.
Active modal control with piezo‐electric layers optimization
Authors: Collet M. , Jezequel L.
Published: April 2007

Modal filter concept is introduced for structural vibration analysis and control. The modal filter is a means to extract the modal coordinates of each mode from the system outputs by mapping the response vector from the physical space to the modal space. This concept was used originally to deal with the spill‐over problem in the control of a continuous system. We have chosen to optimize some semi‐distributed piezo‐electric layers by minimizing the influence of unwanted modes on the sensors and actuators. Confirmation of our computation was obtained by an experimental set‐up of optimal active modal control on a thin composite plate. Thus, experimental optimal control in the independent modal space of this plate has been possible without any effect of spill‐over. The efficiency and the robustness of this procedure was demonstrated by our experimental analysis.
Active structural control by neural networks
Authors: Faravelli L. , Venini P.
Published: April 2007

The present paper develops some alternative schemes to apply back‐propagation neural networks in the area of active structural control. The structural systems referred to are plane hysteretic structures, the restoring forces of which are idealized by an endochronic model. The control algorithms herein developed call for two different neural networks in order to approximate the forward and backward dynamics of the system. The latter network is the actual controller whereas the former one is needed to determine the response of a virtual system upon which no control forces are applied. Results from successful numerical examples are proposed with the objective of computing a quantitative measure of the effectiveness of the system.
Acceleration feedback method applied to active‐passive composite tuned mass damper
Authors: Nishimura Isao , Sakamoto Mitsuo , Yamada Toshikazu , Koshika Norihide , Kobori Takuji
Published: April 2007

This paper discusses the optimization of the active‐passive composite tuned mass damper which was recently proposed by the authors for the purpose of reducing response vibrations of building structures subjected to disturbance excitations such as wind pressures or earthquakes. The parameter optimization, control force reduction, control energy minimization are discussed under several different types of excitations. A harmonic excitation, a stationary white noise and a non‐stationary random excitation such as earthquake are all considered for the derivation of formulae.
Seismic performance of buildings with a class of adaptive nonlinear hybrid systems
Authors: Barbat A. H. , Rodellar J. , Molinares N. , Ryan E. P.
Published: April 2007

A class of hybrid control system which combines a passive nonlinear base isolator with an active controller is analyzed. The passive component of the system has a hysteretic behaviour. A single control force is applied on the structural base by means of a new adaptive control strategy, not requiring knowledge of the system parameters and the excitation and able to handle the typical nonlinearities associated with base isolators. A numerical study is performed to assess the improvement of the behaviour of buildings equipped with this control system.
A numerical controllability test for distributed systems
Authors: Bourquin Frédéric
Published: April 2007

The concept of exact controllability of continuous systems is a cornerstone of feedback design. A simple numerical procedure to test whether this fundamental property does hold or not is presented. It yields additional qualitative informations on the control system. It is based on a sound mathematical analysis. A few numerical tests suggest potential applicability to complex systems.
Control strategies for a slender structure
Authors: Roberti Vincent , Lamarque Claude Henri , Jezequel Louis
Published: April 2007

In this study we start from a modelization by finite elements of a 150 m high tower and try to introduce various control scenarii into the model. The model is realistic in terms of orders of physical size for masses, stiffnesses and other geometrical and mechanical data. We hope to compare control strategies on this model. Each of the control process is compatible with a technological achievement (e.g dampers). The control is provided by actuators that must be located in the building. We compare the energies to get in each control type and the reached efficiency. The global target is to find out a control law model technologically transposable to an actual structure and to define the best control strategy, i.e. to find out the best compromise between the energy to be provided, the reducing in vibratory levels, the actuator location and the actuator operating safety. These elements could be defined as “control criteria”. Among the several possible sollicitations, we will focus on seism‐type sollicitations and will define the actuators location in relation to the building architecture. We will simulate the building behaviours with and without control and will compare the results in terms of vibratory level reductions and energies at work.
Active structures for vibration suppression and precision pointing
Authors: Preumont André
Published: April 2007

This paper describes the work performed at ULB for the development of active structures for space applications, using the piezoelectric technology. The control strategy involves two embedded control loops. The inner loop consists of a decentralized active damping using colocated actuator‐sensor pairs and control schemes with guaranteed stability properties. The outer loop consists of a pointing or position control using non‐colocated actuators and sensors. Two examples of active damping are presented: a truss with linear actuators and a plate with piezo strips. Next, a position control is developed for the truss. The control law is derived from the frequency‐shaped LQG methodology, using a simplified model of the actively damped structure; the band‐width of the control system includes the first two flexible modes of the structure. It is demonstrated that the active damping improves substantially the performance and the robustness of the position control loop, inside and outside its bandwidth.
Displacement feedback control of structures
Authors: Chung L. L. , Wu L. Y. , Jin T. G.
Published: April 2007

Even though displacement signal is superior to velocity and acceleration signals from the viewpoint of measurement noise, direct displacement feedback is considered to be unfeasible. In this paper, displacements of the previous time steps are also introduced into the on‐line calculation of the control forces so that displacement feedback control becomes feasible. A multi‐step displacement feedback control algorithm is derived through optimization process such that certain prescribed quadratic performance index is minimized. Control forces are simply generated from displacement information of the current and previous time steps. The feasibility of the proposed control algorithm is verified numerically by the tendon control of structures subjected to real earthquake excitation. The control effectiveness of the proposed control algorithm is close to that of state feedback control algorithm. A small number of sensors and controllers, and simple on‐line calculation of control forces, make the proposed control algorithm favorable to real‐time control implementation.
Combined fuzzy‐deterministic semi‐active control of a landing gear
Authors: Fiume I. , Ghiringhelli G. L.
Published: April 2007

A fuzzy correction of a deterministic semi‐active control applied to an aircraft landing gear is presented. An existing computer code has been modified to allow its numerical verification during simulated drop tests and landings. The correction of the control action applied by the fuzzy controller seems to improve the dynamic response by reducing the amplitude of vertical ground load fluctuations.
Effect of time lag and use of compensators in the active control of buildings subjected to earthquake excitations
Authors: Suner Ahmet , Nagchaudhuri Abhijit , Utku Senol
Published: April 2007

This work studies the determination of controls to suppress the vibration of a building structure subjected to earthquake excitation. Also studied are the effect of time delay in controls on the response of the structure, determination of time delay limits, and time delay compensation. The control problem is nonautonomous due to the existence of external excitation during the application of controls. The control methods that are used in the autonomous system cannot be applied directly to the nonautonomous problem. Therefore the methods that may be applicable to the nonautonomous problem need to be investigated. In this study, the problem is formulated as a disturbance rejection problem. Determination of controls is discussed with the help of insight provided by classical control methods. A simple control method which is based on large feedback gains is implemented. Time delay effect and compensation are studied through the use of classical control methods.
Analogue vibration cancellation by means of piezoelectric elements
Authors: Jenkins D. F. L. , Cunningham M. J. , Clegg W. W.
Published: April 2007

An active vibration control system has been developed based upon analogue feedback and optical vibration sensing. Composite piezoelectric films have been deposited directly onto the cantilever to provide a means of actuation and micro‐positioning. The system operates such that unwanted vibrations in the cantilever are removed and yet it remains possible to deflect the cantilever statically or dynamically as required. Results are presented for such a system.
Modelling of a plate including a distribution of piezoelectric transducers and an electronic network ‐ optimization of circuit parameters
Authors: Lenczner Michel
Published: April 2007

The Besançon “Matériaux Intelligents” group is working on theoretical and practical aspects of design of dynamical stabilizers for realistic distributed systems. This paper is related to the modelling of an elastic multilayered plate including distributed piezoelectric actuators and a distributed electrical circuit. The derivation of the model is based on asymptotic methods. It is shown that the electrical circuit is a dynamical stabilizer for plate vibrations. An optimization procedure of circuit parameters is formulated and numerical results are discussed.
Feedback control of flexural waves in beams
Authors: Mace B. R. , Jones R. W.
Published: April 2007

The control of bending waves in a thin beam using a collocated feedback method is discussed with special reference to the case of a system comprising a displacement sensor and a force actuator. Control strategies involving vibration isolation (i.e. reducing wave transmission) and energy absorption (i.e. reducing scattered energy) are considered. Digital implementation is discussed and some results presented.
Non Gaussian closure techniques for the analysis of R‐FBI isolation system
Authors: Muscolino G. , Pirrotta A. , Ricciardi G.
Published: April 2007

The Resilient‐Friction Base Isolator (R‐FBI) stochastic response under severe ground motion modelled as a stationary and non‐stationary zero mean stochastic white noise processes is performed. The moment equation approach is applied and the non‐normal response is obtained by means of a non‐Gaussian closure technique, based on the Gram‐Charlier asymptotic expansion of the response probability density function. Results are compared with the equivalent non linearization technique and with results obtained by means of Monte Carlo simulation.
Towards the use of the hilbert transform and neural intelligence in structural non‐linearity detection
Authors: de Stefano A. , Sabia D. , Sabia L.
Published: April 2007

This paper illustrates a new method for the identification and classification of non linearities in vibrating systems characterised by different non linear stiffness laws. It uses the Hilbert transform in the time domain and introduces the concept of analytical signal of the dynamic response to describe a systems non‐linear behaviour through the representation of motion in a three‐dimensional plane. This procedure generates cyclic paths (referred to as “orbits”) whose shape turns out to be markedly affected by the non‐linear type of behaviour being investigated and can be clearly distinguished from the shapes reflecting different types of non‐linear behaviour. This distinctive feature of the orbits prompted the idea of training hierarchical neural networks to recognise and classify the different shapes. This investigation examines vibrating systems characterised by five different types of non‐linear stiffness.
A scale study of electro‐rheological fluid dampers
Authors: Gordaninejad F. , Bindu R.
Published: April 2007

The goal of this study is to develop a scale analysis for predicting the behavior of cylindrical electro‐rheological fluid (ERF) dampers. Theoretical and experimental scale studies are conducted to investigate the effects of the length of dampers and applied electric field strength on the damping and stiffness coefficients of ERF shock absorbers. It is demonstrated that by employing the results obtained from smaller size prototypes, the damping coefficient of larger size dampers can be estimated with reasonable accuracy.
Design of the nations bank corporate center
Authors: Horvilleur Javier F.
Published: April 2007

The paper describes the structural design of Nations Bank Corporate Center. The topics addressed include the structural system selection process used during preliminary design. A complete description of the reinforced concrete frame is presented with emphasis placed on wind engineering, seismic design and the exterior frame gravity analysis. Differential shortening of core and exterior columns and compensation methods used during construction are presented. Temperature effects are also discussed. Finally, the tower foundation and value engineering changes which resulted in structural savings of over 1.6 million dollars are described. The paper is written for engineers not familiar with the design of Tall Buildings and aims to present in some detail the problems and solutions encountered in the structural design of Nations Bank Corporate Center.
Wind resistant design of a tall building with an ellipsoidal cross section
Authors: Itoh Masaru
Published: April 2007

This paper summarizes the results of the wind design carried out for the Act Tower building in Japan. Wind tunnel tests were performed in order to estimate the building response for different wind directions. Undesirable building motion perceived by building occupants is also studied and antivibration systems have been installed to solve this problem.
Performance of prefabricated high strength welded wire grids in ductile concrete shear wall boundary elements
Authors: Baumann Hanns U.
Published: April 2007

The performance of a new proprietary concrete reinforcement product, BauMesh, when used as confinement reinforcement in ductile concrete shear walls is discussed.

Large material and labor savings are achieved when concrete shear walls are reinforced with these new high strength welded wire ladders positioned at close spacing (3 o.c.) along the length of the longitudinal reinforcement to ensure a non‐brittle ductile response to violent earthquake generated cyclic forces.

Design, quality control during manufacture, installation, and the observed performance of a 17‐story San Francisco ductile shear wall building during the Loma Prieta earthquake are discussed.
Seismic eccentrically braced frames
Authors: Tsai K. C. , Yang Y. F. , Lin J. L.
Published: April 2007

This paper provides an overview of the behavior and design of seismic‐resistant eccentrically braced frames (EBFs). Basic characteristics of EBFs are first discussed. The important effects of link length on the performance of EBFs are reviewed. The capacity design concept for EGFs is then addressed. The paper addresses several design issues that appear to have been inadequately considered either in current practice or in the emerging seismic code provisions. Some important observations are provided from pseudodynamic tests of large EBFs and experimental studies of EBF subassemblages with link‐to‐box column connections conducted recently. Future research needs are discussed.
Investigation of current seismic design provisions for reinforced masonry shear walls
Authors: Kariotis John C. , Rahman Auybur , El‐Mustapha Ahmad M.
Published: April 2007

Current seismic design provisions were investigated to determine if optimum designs resulted from their use. Forty‐two components of recorded ground motions were used for the investigation. These ground motions were recorded in the Imperial Valley in 1940 and 1979. These ground motions were assumed to contain a consistent value of soils factor. The tabulation of the Imperial Valley ground motion revealed that these motions had mean velocity‐acceleration ratios and velocity and acceleration amplification factors that exceeded those determined by prior studies. The investigation confirmed that a modified seismic design formula provided a more consistent dynamic behavior for reinforced masonry shear walls. The investigation also studied the influence of reinforcement ratios of masonry shear walls, the influence of under and excess strength, and the effectiveness of stiffness modification in lieu of strength modification. The investigations supported the conclusions that limitation of the vertical reinforcement ratio increases the displacement ductility of reinforced masonry shear walls, that the current NEHRP Recommended Provisions require a near optimum required strength, and that modification of the stiffness of the shear wall, in lieu of strength modification, is highly beneficial in limiting nonlinear displacements of reinforced masonry shear walls.
Selection of earthquake records for seismic design of tall buildings
Authors: Naeim Farzad
Published: April 2007

One of the most difficult questions that the designer of tall earthquake resistant buildings must address is the determination of the critical earthquake. This is the earthquake ground motion that will drive the structure being designed to its critical response. This paper seeks to help the seismic design engineer address this difficult problem by identification of the severity and damage potential of critical components obtained from a database of more than 5000 records of strong earthquake ground motion. These records virtually represent all the available North American and Hawaiian records written by ground‐level instruments for the period of 1933–1992. Elastic and inelastic response and energy spectra are studied. Spectral data are sorted in terms of the mean value of the response parameter in bracketed bands of the fundamental period.
Behavior state analysis and seismic performance evaluation of a tall masonry building in the Loma Prieta earthquake
Authors: Hart Gary C. , Jaw Jing‐Wen
Published: April 2007

A behaviour state analysis is performed on a ten story concrete masonry building that was located in the City of Santz Cruz, which is in the epicentral region of the Loma Prieta earthquake. The building has three types of shear walls (L, T and rectangular) and the behavior state analysis described in the paper first characterizes the expected load deflection response and ductility of each of these shear walls. Then a building system model is developed from these component shear walls models and the load deflection behavior is quantified. This expected load verses deflection behavior of the building is then used to comment on the observed response of the building.
Two stage condensation procedure for free vibration characteristics of framed tube buildings
Authors: Singh Y. , Nagpal A. K.
Published: April 2007

An efficient two stage condensation procedure for the free vibration characteristics of framed tube buildings is presented. In stage 1, the number of d.o.f. is reduced through constraining for which parabolic shape functions are used. In stage 2, the constraints are gradually relaxed using a Gauss—Seidel iterative technique. The procedure is general and can be used for framed tube buildings having any range of member properties and any mass distribution. The method yields accurate results and requires only a fraction of the CPU time and storage locations needed in the standard method. It can be employed to solve frame tube buildings problems of any practical size on microcomputers as well.
A study of earthquake response in a 15‐story reinforced‐concrete frame‐tube model in a shaking table test
Authors: Jiwei Wang , Dajun Ding , Di Zhou
Published: April 2007

Through a series of shaking table tests on a 15‐story regularly hexagonal reinforced‐concrete frame‐tube model of 1:20 scale, the regularities of natural frequencies, the mode shapes and critical damping values of the structure are analysed and the dynamic responses of the structure under one‐dimensional (horizontal or vertical) and two‐dimensional (horizontal and vertical) earthquake waves are studied. In particular, the influences of vertical waves on dynamic response and the failure mechanism of the structure are emphasized in the discussion. Using a finite element program based on a three‐dimensional bar system, the nonlinear dynamic analysis for the test structure is conducted, and finally the calculated and experimental results are compared. Additionally, the influences of vertical earthquake waves on the failure of reinforced‐concrete frame‐tubes is approached using the finite element method and a conclusion consistent with the experimental results is obtained.
Implications of the 1994 northridge earthquake ground motions for the seismic design of tall buildings
Authors: Naeim Farzad
Published: April 2007

Design characteristics of selected 1994 Northridge strong motion records are evaluated. Instrumental, spectral, and energy content attributes of the records are examined. Seismic design implications of these data for tall buildings are discussed. The weaknesses of the current seismic design philosophy in dealing with near‐field strong ground motions, representing significant acceleration pulses, are demonstrated and recommendations for improving both the demand side and the capacity side of current seismic design formulations are provided.
A technique for evaluating the effect of beam‐column joint deformation on the lateral flexibility of steel frame building structures
Authors: Charney Finley A. , Horvilleur Javier F.
Published: April 2007

Accurate analysis of steel framed structures requires a careful assessment of the contribution of beam‐column joint deformation to overall structural flexibility. Unfortunately, traditional structural analysis has either ignored the deformations by assuming fully rigid joints, or has approximated the effects by using centerline analysis. Some computer programs use a hybrid technique wherein the beam‐column joint region is assumed to be partially rigid. Due in part to the fact that the preceding analysis technique violate local equilibrium within the joint, the results produced are unrealiable. In this paper, a new analysis technique is presented for beam‐column joint analysis. The method is based on a virtual force analysis of an isolated subassemblage, with local equilibrium within the joint being strictly satisfied. When compared with results of finite analysis of full three dimensional subassemblages, the method has been found to be very accurate.
Interstory drift design and damage control issues
Authors: Mayes Ronald L.
Published: April 2007

This paper addresses post‐earthquake functionality of buildings by focusing on one of the key aspects of damage control design‐interstory drift. It is generally recognized that interstory drift can be used as a measure of expected damage. In order to control damage, the designer must understand the relationship between interstory drift and different levels of damage. Current code provisions for interstory drift, which attempt to address life safety primarily, are reviewed. The limitations of these provisions when applied to damage control design are discussed. An overview of current research on establishing a relationship between interstory drift and damage levels in nonstructural and structural elements is provided.
Use of active mass dampers for wind and seismic control on super‐high‐rise buildings
Authors: Huang King M. , Chou T. J.
Published: April 2007

Active mass dampers applied to an 85‐story high‐rise building are investigated in this study. The building was originally designed with an interstory drift ratio under design wind loads of up to 0.004. Stiffening the building through filling the steel box columns with concrete was proposed. However as shown by analysis, the reduction of interstory drift was restricted still within inadmissible range. Active mass dampers were then proposed as an alternative solution. Dampers by two different manufacturers were used, the two systems employing similar mechanisms. Analytical results indicate that both displacement and acceleration of the building are significantly reduced by the incorporation of active mass dampers, however the lack of a reliable backup power system is a major concern. Also, effective control of the structural responses caused by a severe earthquake may still requires further studies.
Continuous pulse and hybrid control of structures
Authors: Pantelides Chris P. , Tzan Shyh‐Rong , Nelson Paul A.
Published: April 2007

In recent years, passive as well as active control methods have been implemented for structural motion reduction of tall buildings in earthquakes. An active control method for the inelastic response of tall buildings is presented. The proposed method of continuous pulse control uses closed‐loop feedback control as a combination of two algorithms. The first is a linear control algorithm‐instantaneous optimal control‐and the second is a pulse control algorithm‐the pulse control algorithm‐which applies a corrective pulse when a prespecified structural velocity threshold is exceeded. The control forces required by active control systems to reduce the seismic response of tall buildings can be quite large. On the other hand, passive control systems such as the viscoelastic dampers do not require external energy for their operation. The possibility of combining viscoelastic dampers and the active bracing system for reducing the required control forces is examined. The combination of passive and active devices improves safety, serviceability and the comfort of the building's occupants.
How to Do More Than Manage Inflation's Effects
Authors: Austin James E.
Published: April 2007

As the countries of Eastern Europe move to become more market‐oriented, they may experience bouts of high infation. This isn't something limited to the Third World or Latin America. Such a possibility, however, should not dampen MNC interest in doing business in any of these parts of the world. In countries subject to inflation, profitability is still possible. Learning to manage its effects can even create competitive advantage.
Strategic partnering in Eastern Europe
Authors: Lewis Tom , Turley Mark
Published: April 2007

There are alternatives to the much‐touted “joint venture” in Eastern Europe. Some of these, such as licensing and cooperation agreements, have actually been available for some time. Others, like wholly owned subsidiaries, mergers, and acquisitions, are in the early stages of development. Clearly, the pace of reform indicates it is time to rethink the conventional wisdom on corporate development in Eastern Europe.
A European Sherman?
Authors: Walley Ray
Published: April 2007

EC anti‐trust legislation is based on Articles 85 and 86 of the Treaty of Rome. You need to know these articles of law if you plan to aggressively market in the EC.
The implications of 1992 for financial management
Authors: Groothaert Jacques
Published: April 2007

With the process of integration gathering momentum all the time, the implications of 1992 for the European financial sector merit special attention.
International M&As: Post‐Merger Integration
Authors: Radway Robert J.
Published: April 2007

Mergers and acquisitions often fail to work out according to plans–partly because management fails to set guidelines for the post‐merger aspects of the deal. Post‐merger planning–especially in international M&As–is a crucial factor in long‐term success.