bluuebunny/crossref_metadata_2025 huggingface dataset:
The Use of Time-Dependent Temperature Response Curves for the Generation of (Dynamic) Compact Thermal Models
Authors: Lasance Clemens J. M. , Sabry Mohamed-Nabil
Published: May 2010

The paper presents recent developments in time-dependent (dynamic) compact thermal modeling. Dynamic thermal effects in electronic circuits manifest themselves at all levels from device to system with a serious impact on both reliability and performance especially as the device feature size shrinks below the submicron scale. Design and analysis of electro-thermal systems rely increasingly on compact models due to the ever-increasing problem complexity. Four application fields of dynamic compact thermal models (DCTM’s) are highlighted. The focus of the paper is on practical methods to generate DCTM’s. Three examples are discussed, typical for most package styles: a TQFP (Thin Quad Flat Pack), a BGA (Ball Grid Array) and a power package (SILP). Finally, a method is presented to calibrate detailed models using experimental response curves, thereby eliminating the need for the sometimes unreliable and time-consuming steady state measurements.
Effect of Reflow Parameters on Solder Wetting
Authors: Kang Suk Chae , Baldwin Daniel F.
Published: May 2010

Reflow parameters during assembly are ramp rate, soak time, soak temperature, peak temperature, time above liquidus, and cooling rate. These reflow parameters constructs the temperature profile of reflow process and determine the quality of interconnects in the electronics products. To investigate the effect of reflow parameters on solder interconnect wetting, the wetting rate of a single liquid solder sphere on a metal substrate with variation of reflow parameters were experimentally measured and the constitutive model for the dynamics of solder wetting was suggested.
A Method for Improving Component Decoupling Using Advanced Capacitor Under Ball Grid Array (ACUB)
Authors: Dishongh Terry , Searls Damion , Roth Weston C. , Peter Erik
Published: May 2010

Industry demands on power delivery continue to increase with higher performance silicon products. As a result, higher current sustainability and better transient response are key parameters frequently sought in successful power delivery designs. One key design feature for improved transient response involves locating decoupling capacitance as close to the load as possible. At the board level, this is typically accomplished by placing capacitors around the immediate vicinity of the load. With a set of identical capacitors in parallel, total capacitance is essentially a multiple of the number of caps while the effective series resistance and inductance is divided. However the realities of package and motherboard design can often limit the number and size of the capacitors placed in the vicinity of the load. In some cases, the capacitors may interfere with other routings to and from the component. In other cases, placement of the capacitors with respect to the DC current path may limit their effectiveness by inducing a large effective series inductance to the load. This paper describes a potential design method for maximizing capacitor effectiveness while minimizing its impact on other board features. The design is primarily implemented in board assembly and involves placing capacitors directly between power and ground board-component solder joints. As an extension of Capacitor Under BGA designs, this method is termed Advanced Capacitor Under BGA (ACUB). Using ACUB can improve load decoupling, but can require new approaches to board and component assembly. This paper discusses a number of potential design improvements allowed for using this design approach. In addition, factors involved in successful assembly are discussed and sets of proof-of-concept prototype designs are presented along with assembly results. From this, some designs with potential for further development are identified and next steps discussed.
Creep and Microstructural Evolution in Lead-Free Microelectronic Solder Joints
Authors: Dutta I. , Park C. , Choi S.
Published: May 2010

Microelectronic solder joints are typically exposed to aggressive thermo-mechanical cycling (TMC) conditions, resulting in significant strain-enhanced microstructural coarsening during service. This microstructural evolution produces continuously evolving mechanical properties during extended use. Since solder joint life is dictated largely by the creep strain range, it is necessary to develop microstructurally adaptive creep models for solders to enable accurate prediction of joint life. In this paper, we present (1) a new closed-form creep model incorporating microstructural coarsening in lead-free solders, which can be easily incorporated into life-prediction models; and (2) a methodology for impression creep testing of Sn-3.5Ag solders which can potentially enable creep testing of individual flip chip or BGA balls in a package. The proposed creep model incorporates the effects of both static and strain-enhanced coarsening of second phase intermetallic particles which are present in lead-free solders, and shows that as a joint undergoes TMC, the creep rate increases continuously, adversely impacting life. This inference is supported by the impression creep experiments, which are shown to capture the essential features of creep in Sn-Ag alloys, in accordance with the available literature. It is also shown that the creep resistance of a given alloy composition is strongly dependent on the microstructure, making it important that creep data used for joint life prediction be based on testing of actual joints or very tightly controlled microstructures.
Compact Thermal Representations for Several Fundamental Shapes in Forced Convection
Authors: Brucker Kyle A. , Ressler Kyle T. , Majdalani Joseph
Published: May 2010

In the cooling of electronic packages, the task of simulating large arrays of heat sinks is often accomplished by the use of compact models. These simpler models attempt to capture the thermal and flow resistance characteristics of a representative heat sink while ignoring secondary detail. In the porous block model, an equivalent thermal conductivity is assigned to the fluid that enters the ‘porous’ space above the heat sink base that was once occupied by the fins. This artificially enhanced thermal conductivity enables the porous block of fluid to exhibit the same thermal resistance as that of the original heat sink. Due to the three-dimensional distribution of the thermal resistance in space, temperature maps associated with the resulting model provide better agreement with detailed numerical simulations than is possible with other models based on two-dimensional flat plate or thin sheet approximations. In this paper, we present closed-form expressions for the equivalent thermal conductivity associated with a large number of heat sink shapes in a forced convection environment.
A High-Resolution Dry-Contact Acoustic Imaging of the Solder Joints for Ball Grid Array Assembly
Authors: Tohmyoh Hironori , Saka Masumi
Published: May 2010

A new concept of acoustic microscopy for ball grid array assembly is reported. Commonly, the acoustic microscopy has to be performed with immersing the package in the coupling liquid. On the other hand, the present technique does not require the immersion of the package in the liquid, because the transduction of high frequency ultrasound is performed thorough a thin solid layer. A theoretical model is shown to perform the transduction of ultrasound more effective than usual immersion, and an acoustic matching layer, which realizes the signal amplification and the modulation, is shown. The acoustic imaging of the solder joints of a wafer level package is carried out by the present dry-contact and usual immersion techniques. The dry-contact acoustic images show the defective joint clearly, and the detectability of the defective joint is improved remarkably as compared with the usual immersion images.
Numerical Optimization Study for a Parallel Plate Impingement Heat Sink
Authors: Shah Amit , Sammakia Bahgat , Srihari Hari , Ramakrishna Koneru
Published: May 2010

This paper presents the numerical analysis of an impingement heat sink designed for use with a specific blower as a single unit. Shat et al. (2002) had performed a fin shape optimization study for the same heat sink and concluded that a de populated central zone, just under the center of the fan, provides a better thermal performance as compared to the heat sink geometries with fin material under the fan. The results presented in this paper are an extension to the study described in Shah et al. (2002). The effects of removal of fin material from the end fins, the total number of fins, and, the reduction in the size of the hub have been investigated. The removal of fin material from the end fins results in the better thermal and hydraulic performance. The reduction in the size of the hub causes a more uniform distribution of air inside the heat sink. The increase in the number of fins indicates a slightly better thermal performance, accompanied by a considerably increased pressure drop. Finally a new optimal heat sink design has been reported. This design is shown to perform better as compared to the original heat sink design under the actual fan operating characteristics.
Nonlinear Behavior Study on Effect of Hardening Rule of Lead Free Solder Joint
Authors: Kim Do-Seop , Yu Qiang , Shibutani Tadahiro , Shiratori Masaki
Published: May 2010

In lead free solder joint, the hardening characteristics must be considered accurately in the FEM (Finite element method) analysis because the estimation of the stress arising at the interface in solder joint is important and the work hardening after yielding is relatively remarkable. In this paper, the effect of the hardening rule on stress and nonlinear strain estimation of lead free solder joint is examined using mechanical fatigue test and FEM analysis. And it is proven that the equivalent stress and nonlinear strain of lead free solder joint can be calculated by using isotropic hardening rule in stead of kinematic hardening rule like the Sn-37Pb eutectic solder.
Measurement of Transverse Deflection for Composite Laminates Using Holographic Interferometry
Authors: Lin Jin-Chein , Yang T. Y. , Chang L. C.
Published: May 2010

Holographic interferometry is an accurate and important technolngy. Through the application of recording and reconstructing light waves, one can solve a wide variety of mechanical or engineering problems caused by internal stresses, mechanical, electrical or thermal effects. The mechanical properties of composite materials, such as, deflection, strain and stress will be determined by the fiber types, the cross-section of specimens ans the fiber orientation of composite laminate. The purpose of this investigation will discuss the holographic technique and its application of measurement of transverse deflection for various composite laminates. The analysis for both theoretical and experimental results will be presented, and the effect of fiber orientation for composite laminate will be studied in this paper.
The Effect of Intermetallic Compound in Solder Joint Fatigue Life Prediction Using Finite Element Modeling
Authors: Masum Hossain Mohammad , Agonafer Dereje , Viswanadham Puligandla , Reinikainen Tommi
Published: May 2010

The life-prediction modeling of an electronic package requires a sequence of critical assumptions concerning the finite element models. The solder structures accommodate the bulk of the plastic strain that is generated during accelerated temperature cycling due to the thermal expansion mismatch between the various materials that constitute the package. Finite element analysis is extensively used for simulating the effect of accelerated temperature cycling on electronic packages. There are a number of issues that need to be addressed to improve the current FEM models. One of the limitations inherent to the presently available models is the accuracy in property values of eutectic 63Sn/37Pb solder or other solder materials (i.e. 62Sn/36Pb/2Ag). Life prediction methodologies for high temperature solders (90Pb/10Sn, 95Pb/5Sn, etc.) or lead-free based inter-connects materials, are almost non-existent due to their low volume use or relative infancy. [1] Another major limitation for the models presently available is excluding the effect of intermetallic compound (Cu6Sn5, Cu3Sn) formation and growth between solder joint and Cu pad due to the reflow processes, rework and during the thermal aging. The mechanical reliability of these intermetallic compounds clearly influences the mechanical integrity of the interconnection. The brittle failures of solder balls have been identified with the growth of a number of intermetallic compounds both at the interfaces between metallic layers and in the bulk solder balls. In this paper, the effect of intermetallic compound in fatigue life prediction using finite element modeling is described. A Chip Scale Package 3D Quarter model is chosen to do the FE analysis. Accelerated temperature cycling is performed to obtain the plastic work due to thermal expansion mismatch between the various materials. Solder joint fatigue life prediction methodologies were incorporated so that finite element simulation results were translated into estimated cycles to failure. The results are compared with conventional models that do not include intermetallic effects. Conventionally available material properties are assumed for the eutectic 63Sn/37Pb solder and the intermetallic material properties. The importance of including intermetallic effect in finite element modeling will be discussed.
Multi-Scale Optical Design for Global Chip-to-Chip Optical Interconnections and Misalignment Tolerant Packaging
Authors: Christensen Marc P. , Milojkovic Predrag , McFadden Michael J. , Haney Michael W.
Published: May 2010

As transistor densities on integrated circuits (ICs) continue to grow, off-chip bandwidth is becoming an ever-increasing performance-limiting bottleneck in systems. Electronic multichip module (MCM) and printed circuit board (PCB) packaging technology has not kept pace with the growth of inter-chip interconnection requirements. Recent advances in “smart pixel” technology offer the potential to use optical interconnects to overcome the inter-chip I/O bottleneck by linking dense arrays of Vertical Cavity Surface Emitting Lasers (VCSELs) and photodetectors. For optical interconnections to be relevant to real systems they must be able to be manufactured and packaged inexpensively and robustly. This paper discusses an optical design and packaging approach that utilizes multiple sizes (or scales) of optical elements to simplify the design of the optical interconnection and coupling while providing an enhanced degree of insensitivity to misalignments inherent in the packaging of these systems. The scales of the optical elements described are: the size of the IC (termed macrooptical), the size of the pitch of optical IO (termed microoptical), and sizes in between (termed mini-optical) which are smaller than the size of the IC but cover several optical IO. This paper describes the utility of elements of each of these scales and shows that through the combination of them simple robust systems can be constructed. Two case studies for applying this multi-scale optical design are examined. The first case study is a global chip-to-chip optical interconnection module (termed FAST-Net) that uses a macro lens array and mirror to effect the all-to-all optical interconnection pattern among an array of ICs on a single board. Micro- and mini-scale optical elements simplify the design of the macro-lens by performing corrections at scales where they are more effective. In this system over 11,000 optical links are implemented across a 5 inch multi-chip module with diffraction limited RMS spot sizes and registration errors less than 5 microns. The second case study analyzes designs for board-to-board optical interconnections with throw-distances ranging from 1 millimeter to several centimeters. In this case micro- and mini-scale optical interconnections provide insensitivity to misalignments. The results show the feasibility of an optical coupler that can tolerate the typical packaging misalignments of 5 to 10 mil without placing rigid constraints on the angular sensitivity of the modules. The multi-scale optical interconnection and coupling concept is shown to provide an approach to simplifying design and packaging — and therefore the costs — associated with implementing optical interconnection systems.
Multi-Scale Modeling of High Power Density Data Centers
Authors: Rambo Jeffrey D. , Joshi Yogendra K.
Published: May 2010

Data center facilities, which house thousands of servers, storage devices and computing hardware, arranged in 2 meter high racks are providing many thermal challenges. Each rack can dissipate 10–15 kW, and with facilities as large as tens of thousands of square feet, the net power dissipated is typically on the order of several MW. The cost to power these facilities alone can be millions of dollars a year, with the cost to provide adequate cooling not far behind. Significant savings can be realized for the end user by improved design methodology of these high power density data centers. The fundamental need for improved characterization is motivated by inadequacies of simple energy balances to identify local ‘hot spots’ and ultimately provide a reliable modeling framework by which the data centers of the future can be designed. Recent attempts in computational fluid dynamics (CFD) modeling of data centers have been based around a simple rack model, either as a uniform heat generator or specified temperature rise across the rack. This desensitizes the solution to variations of heat load and corresponding flow rate needed to cool the servers throughout the rack. Heat generated at the smaller scales (the chip level) produces changes in the larger length scales of the data center. Accurate simulations of these facilities should attempt to resolve the range of length scales present. In this paper, a multi-scale model where each rack is subdivided into a series of sub-models to better mimic the behavior of individual servers inside the data center is proposed. A Reynolds-averaged Navier-Stokes CFD model of a 110 m2 (1,200 ft2) representative data center with the raised floor cooling scheme was constructed around this multi-scale rack model. Each of the 28 racks dissipated 4.23 kW, giving the data center a power density of 1076 W/m2 (100 W/ft2) based on total floor space. Parametric studies of varying heat loads within the rack and throughout the data center were performed to better characterize the interactions of the sub-rack scale heat generation and the data center. Major results include 1) the presence of a nonlinear thermal response in the upper portion of each rack due to recirculation effects and 2) significant changes in the surrounding racks (up to 10% increase in maximum temperature) observed in response to changes in rack flow rate (50% decrease).
Life Prediction of SnPb and SnAg Solder Joints in PBGA Packages Using a Severity Metric
Authors: Kim Donghyun , Mawer Andrew , Moon Tess J. , Masada Glenn Y.
Published: May 2010

A severity metric is developed to predict the life of SnPb and SnAg solder joints in PBGA packages by quantitatively estimating the changes in damage arising from different board configurations and accelerated thermal cycle tests (ATC). Damage measures include time-dependent creep, time-independent plastic deformation, and an effective stress that is computed from the ATC parameters of temperatures, dwell-time, and ramp rates and from package geometries on the printed wiring board. Life prediction using this severity metric has been applied to 24 sets of test data on SnPb and SnAg solder joints in 357-PBGA packages and include three post-processing conditions (aged at 150/160°C, quenched at 0°C, and air-cooled), three ATC test conditions (0–100°C, −40–125°C, and −55–125°C), and four package-on-board geometric configurations. Statistical analysis is provided to compare the life predictions based upon the severity metric and from ATC testing—predicted joint life is well within one standard deviation of the experimental mean value of life for most of the 24 cases. The severity metric can be used to quantify the effects of design and manufacturing choices on joint life.
Drop Reliability of Corner Bonded CSP in Portable Products
Authors: Tian Guoyun , Liu Yueli , Lall Pradeep , Johnson R. Wayne , Abderrahman Sanan , Palmer Mike , Islam Nokib , Suhling Jeffrey , Crane Larry
Published: May 2010

The use of CSPs has expanded rapidly, particularly in portable electronic products. Many CSP designs will meet the thermal cycle or thermal shock requirements for these applications. However, mechanical shock (drop) and bending requirements often necessitate the use of underfills to increase the mechanical strength of the CSP-to-board connection. Capillary flow underfills processed after reflow, provide the most common solution to improving mechanical reliability. However, capillary underfill adds board dehydration, underfill dispense, flow and cure steps and the associated equipment to the assembly process. Corner bonding provides an alternate approach. Dots of underfill are dispensed at the four corners of the CSP site after solder paste print, but before CSP placement. During reflow the underfill cures, providing mechanical coupling between the CSP and the board at the corners of the CSP. Since only small areas of underfill are used, board dehydration is not required. This paper examines the manufacturing process for corner bonding including dispense volume, CSP placement and reflow. Drop test results are then presented. A conventional, capillary process was used for comparison of drop test results. Test results with corner bonding were intermediate between complete capillary underfill and non-underfilled CSPs. Finite element modeling results for the drop test are also included.
Measurement of Stress and Delamination in Flip Chip on Laminate Assemblies
Authors: Rahim M. Kaysar , Suhling Jeffrey C. , Copeland D. Scott , Jaeger Richard C. , Lall Pradeep
Published: May 2010

Mechanical stress distributions in packaged silicon die that have resulted during assembly or environmental testing can be accurately characterized using test chips incorporating integral piezoresistive sensors. In this paper, an overview of recent measurements made in flip chip on laminate assemblies with (111) silicon test chips is presented. Transient die stress measurements have been made during underfill cure, and the room temperature die stresses in final cured assemblies have been compared for several different underfill encapsulants. The experimental stress measurements in the flip chip samples were then correlated with finite element predictions for the tested configurations. In addition, stress variations have been monitored in the assembled flip chip die as the test boards were subjected to slow temperature changes from −40 to +150°C. Finally the stress variations occurring during thermal cycling from −40 to +125°C have been characterized. These measurements have been correlated with the delaminations occurring at the die passivation to underfill interface measured using C-mode Scanning Acoustic Microscopy (C-SAM). Using the measurements and numerical simulations, valuable insight has been gained on the effects of assembly variables and underfill material properties on the reliability of flip chip packages.
Advanced Micro Shear Testing for Solder Alloy Using Direct Local Measurement
Authors: Kwon Soonwook , Lee Yuri , Han Bongtae
Published: May 2010

A modified single lap shear test configuration, based on the Iosipescu geometry, is proposed for determination of the constitutive properties of solder alloys. An auxiliary device (extension unit) is introduced to improve the accuracy of measurement. The extension unit is attached directly to the specimen and it converts shear displacements to axial displacements, which are subsequently captured by a high-resolution extensometer. With aid of the extension unit, shear deformations are measured without compensating machine and grip compliance. The specimen configuration includes geometrical constraints at the solder/substrate interfaces in most electronic assemblies. Consequently, the results represent pseudo-continuum properties that take account for grain constraints at the solder/pad interface. They are properties that are more realistic for continuum mechanics based stress studies such as an FEM analysis.
Surface Finish Effects on High-Speed Interconnects
Authors: Wu Xin , Ramahi Omar M. , Brist Gary A. , Cullen Donald P.
Published: May 2010

In printed circuit boards (PCB), the selection of surface finish is a balance of cost, performance and material compatibility consideration. When the operating frequency is in gigahertz range, the signal loss in interconnects has stronger dependence on the material composition of traces, surface finishes, substrates, and geometry of the traces. Skin effects, frequency dependent dielectric properties and the electrical functioning mechanism are important factors that affect signal integrity. In this work, both measurements and finite element method (FEM) based full wave simulation are used to investigate the effects of hot air solder leveling (HASL) and its alternatives on signal degradation of high-speed interconnect structures. For the microstrip line structure, the loss due to surface finishes is negligible. For the differential mode coupled microstrip lines, the loss increment resulted from surface finish can be up to 50%∼200% at 10 GHz. Surface finish caused signal loss must be carefully considered for differential mode interconnects.
Analytical Modeling of Active Cooling Schemes Suitable for Thermal Management of Telecoms Servers
Authors: Heydari Ali , Sabounchi Poorya
Published: May 2010

There is a strong need to improve our current capabilities in thermal management and electronic cooling, since estimates indicate that IC power density level could reach 50 W/cm2 in near future. This paper presents an innovative approach for thermal modeling of active cooling schemes suitable for tight-spaced telecom servers. It is shown that the principles of energy conversion can be used to overcome the problems of thermal resistance narrowing. Cooling schemes such as mesoscale vapor compression refrigeration, liquid cooling, thermoelectric microcooler and microchannel heat sink are discussed and compared in terms of heat dissipation potential, reliability, and packaging application concerns.
Finite Element Parametric Analysis on Fine-Pitch BGA (FBGA) Packages
Authors: Chong Desmond Y. R. , Wang C. K. , Fong K. C. , Lall Pradeep
Published: May 2010

Reduction in size of portable products such as cellular phones and camcorders has led to the miniaturization of integrated circuit packages. Fine-pitch BGA (FBGA) packages has been gaining its popularity due to compact in size and relatively low costing. With further down-sizing in package height, reliability issues like die cracking and warpage have surfaced as potential failures. Die cracks results in malfunction of an IC package, while the latter causes difficulty in board surface mounting. In this study, effects of package height on the die stress and warpage have been assessed by FEA. With overmold height ranging from 0.4∼0.6mm and substrate from 0.16∼0.32mm thick, the Overall Package Thickness coding from “T” (1.00<A< = 1.20mm) to “W” (0.65<A< = 0.80mm) are being analyzed. Results revealed that die stress and warpage decreases with increase in overmold thickness. However, an increment in the substrate thickness constituted to a rise in die stress and warpage. It was found that “top clearance” (distance between active die side and package top) of the package contributed to different trends in die stresses. Trends of results in varying the package and die sizes are also being investigated. The findings have provided guidelines for in-house designers in containing possible failures in FBGA packages.
Auditing the Reliability Capability of Electronics Manufacturers
Authors: Tiku Sanjay , Pecht Michael
Published: May 2010

The globalisation of supply chains has made electronics manufacturers dependent upon worldwide suppliers who provide them with parts or subassemblies. Currently, many manufacturers have to wait until they get the products to assess if they are reliable. This can be an expensive iterative process. As an alternative, it is necessary to define what key processes should comprise the product and process development efforts of suppliers to assure customers that they can supply reliable products. Identification of these key processes can help manufacturers to assess their potential suppliers and/or suppliers to assess themselves. This paper presents a set of key processes and practices that can be used as benchmarks to assess whether an organization has the ability to design, develop and manufacture reliable electronic products. It defines this ability as the reliability capability of an organization.
Feasibility Tests on a Three-Dimensional Base Isolation System Incorporating Hydraulic Mechanism
Authors: Kashiwazaki Akihiro , Shimada Takahiro , Fujiwaka Tatsuya , Umeki Katsuhiko
Published: May 2010

In Japan, a number of three-dimensional base isolation systems have been studied for application to new nuclear plant concepts such as the FBR, but these efforts have not so far yielded practically applicable results. The impeding factor has been the difficulty of obtaining an adequate capacity on the vertical isolator for supporting the mass of an actual structure and for suppressing rocking motion. In this paper, we propose a new three-dimensional base isolation system that should solve the foregoing problem. The system is constituted of a set of hydraulic load-carrying cylinders connected to accumulator units containing a compressed gas, another set of rocking-suppression cylinders connected in series, and a laminated rubber bearing laid under each load-carrying cylinder. The present paper covers a basic examination for applying the proposed system to a commercialized FBR now under development in Japan, together with static and dynamic loading tests performed on a scale model to verify expected system performance. Response analysis reflecting the test results has indicated the proposed system to be well applicable to the envisaged commercialized FBR. The study was undertaken as part of an R&D project sponsored by the government for realizing a three-dimensional seismic isolation system applicable to future FBR’s.
Development of Cable Reinforced 3-Dimensional Base Isolation Air Spring
Authors: Kageyama Mitsuru , Iba Tsutomu , Somaki Takahiro , Hino Hisako , Umeki Katsuhiko
Published: May 2010

In Japan, the study on the development of a 3-dimensional base isolation system to be applied to a nuclear power plant, which requires supreme safety against severe earthquakes, has been carried out since 2000. An idea with the concept of a cable reinforced air spring was proposed as the 3-dimensional base isolation device. The dimension of the air spring applying to the actual power plant is 9 meters in the outer-diameter and 3.5 meters in height. The allowable half strokes are respectively 1.5 meters for the horizontal direction and 0.5 meters for the vertical directions. The supporting weight for a single device is 52MN, where the inner air pressure is about 1.2MPa. This device enables to realize three-dimensional base isolation with a single device, whose characteristics is a natural period of over 4 seconds in the horizontal direction and over 3 seconds in the vertical direction. Furthermore, this device does not require precision mechanical parts just common building materials, which are steel, cable wire, polyester fabric and a rubber sheet. Therefore, the construction cost for this device could be reduced effectively. In order to confirm the performance of the proposed device, experimental tests using the three dimensional shaking table were carried out on the proposed cable reinforced 3-dimensional base isolation air spring, whose outer diameter is 2 meters, being 1/4.5 scale of the actual size. The weight of approximately 392kN including a 4-story steel frame was loaded on the test specimen in order to create inner air pressure of 0.157MPa. As a result, the device was confirmed to function smoothly in three dimensions with natural periods of 1.8 seconds in the horizontal direction and 1.4 seconds in the vertical direction, and is considered that the proposed system can be applied to actual power plants.
Application of Semi-Active Oil Damper System to Base Isolation Systems
Authors: Kawai Takashi , Tsuyuki Yasuo , Inoue Yutaka , Takahashi Osamu , Oka Koji
Published: May 2010

This paper deals with one of the applications of the Semi-Active Oil Damper system, which applies base isolation systems reducing the maximum acceleration. The theory of the Semi-Active Oil Damper system is based on Karnopp Theory. The theory has been actually now in use for a Semi-active suspension system of the latest Shinkansen (New trunk lines) trains to improve passenger’s comfortable riding. Various experiments have been conducted using a single mass model whose weight is 15 ton on the shaking table. This model is supported by the rubber bearing. The natural frequency is 0.33Hz of this system. Two Semi-Active Oil Damper were installed in the model and excited the table for one horizontal direction. The maximum damping force of each Semi-Active Oil Damper used for the model is 4.21 kN. The damper can change the damping coefficient by utilizing two solenoid valves. Therefore, the dynamic characteristic of the damping force has two modes. One is a hard damping coefficient and the other is a soft one. It was confirmed that the maximum acceleration of the Semi-Active Oil Damper system can be reduced more than 20% in comparison with the passive Oil Damper system in our tests.
Design Method of Vertical Component Isolation System
Authors: Kitamura S. , Morishita M.
Published: May 2010

A structural concept of a vertical component isolation system for fast reactors, assuming a building adopting a horizontal base isolation system, has been studied. In this concept, a reactor vessel and major primary components are suspended from a large common deck supported by isolation devices consisting of large coned disk springs. A series of experiments using a simple model for the confirmation of the isolation effect, and a case study of vertical isolation device and plant layout are shown in this paper.
Advanced Tested Technology for Earthquakes and the Shapes of Memory: A Short Film and a Motion-Picture Developed in the Framework of the MUSICA Project
Authors: Martelli Alessandro , Arato Giordano-Bruno , Bellani Enrico
Published: May 2010

This paper provides updated information, with respect to that already given at the 2001 ASME-PVP Conference, on the Project MUSICA (Multimedia for the Development of Innovative Systems for Anti-Seismic Constructions). This project was jointly undertaken by the Italian Agency for New Technology, Energy and the Environment (ENEA) and other partners associated in the Italian Working Group on Seismic Isolation (GLIS) in May 2000, to contribute to information and training on the modern passive control techniques of seismic vibrations through a better, modern use of media. It consists in the development of a series of films of various durations on manufacturing, R&D and applications of the aforesaid techniques, namely seismic isolation, passive energy dissipation, hydraulic coupling by means of shock transmitters, systems formed by shape memory alloy devices, “active sewing” method for masonry buildings, etc. Films are addressed to designers, representatives of the Institutions and the ordinary public, as well. Most of them have already been completed. The short film “Advanced Tested Technology for Earthquakes” (that developed for ENEA within the MUSICA Project) will be shown at the Symposium, together with (if possible) the motion-picture “The Shapes of Memory”.
Analyses of Seismic Isolation Systems in Kyrgyzstan
Authors: Ormonbekov Tynymbek O. , Begaliev Ulugbek T.
Published: May 2010

The purpose of the present work is the analysis of existing methods of seismoisolation in the Kyrgyz Republic at which 95% of territory has seismically active zone with intensity 8, 9 and more. Also an opportunity of application of system seismic protection as rubber-metal bearings.
Seismic Evaluation Procedures of Seismically Isolated Buildings Introduced to the Building Code of Japan
Authors: Midorikawa Mitsumasa , Iiba Masanori , Kani Nagahide , Koshika Norihide , Azuhata Tatsuya
Published: May 2010

The Building Code of Japan (the Building Standard Law of Japan) has been changed from the former prescriptive into performance-based type in June, 2000. This paper presents the evaluation procedures of seismic performance of seismically isolated buildings against major earthquake motions newly introduced to the Building Code of Japan in October, 2000. The evaluation procedures apply the single-degree-of-freedom (SDOF) system, equivalent linearization and response spectrum analysis. The basic concept of seismic design spectra for major earthquake motions is: 1) basic design spectra defined at the engineering bedrock, and 2) evaluation of site response from geotechnical data of surface soil layers. The principle of evaluation procedures is that the predicted response values should not exceed the estimated limit values. The evaluation criteria of each portion of a building are: 1) the isolation system shall be designed so that the maximum response displacement does not exceed the design limit displacement, and 2) the structure above the isolation system and the foundation and structural elements below the isolation system shall be designed so that the working stress does not exceed the allowable stress. The scope of application of the evaluation procedures is: 1) buildings not exceeding 60 meters in height, and 2) base isolation buildings on the soil layers excluding very soft soils.
Semi-Active Vibration Isolation Control for Multi-Degree-of-Freedom Structures
Authors: Nishimura Hidekazu , Okumura Yasuhiko , Shimodaira Seiji
Published: May 2010

In this paper, we propose a design method of a controller for semi-active vibration isolation. We introduce a mechanism of a semi-active damper, which can change the damping in the ratio of the orifice area, in order to obtain the parameter-varying system model. Consideration of the semi-active damper mechanism is appropriate for the design of the gain-scheduled (GS) controller based on linear matrix inequalities (LMIs). The GS controller consists of four-vertex linear time-invaxiant controllers are obtained by the convex interpolation of these controllers. The designed controller switches at zero velocity of the damper and varies according to both the orifice area and the relative velocity of the isolation layer. By carrying out simulations, it is shown that our proposed method is effective for the suppression of seismic response.
Seismic Control Effect for Nonlinear Benchmark Building Using Passive or Semi-Active Damper
Authors: Fukukita Akira , Saito Tomoo , Shiba Keiji
Published: May 2010

We study the control effect for a 20-story benchmark building and apply passive or semi-active control devices to the building. First, the viscous damping wall is selected as a passive control device which consists of two outer plates and one inner plate, facing each other with a small gap filled with viscous fluid. The damping force depends on the interstory velocity, temperature and the shearing area. Next, the variable oil damper is selected as a semi-active control device which can produce the control forces by little electrical power. We propose a damper model in which the damping coefficient changes according to both the response of the damper and control forces based on an LQG feedback and feedforward control theory. It is demonstrated from the results of a series of simulations that the both passive device and semi-active device can effectively reduce the response of the structure in various earthquake motions.
Impact Behavior of Rocking Bridge Piers
Authors: Cheng Chin-Tung , Shih Ming-Hsiang
Published: May 2010

This research aims to investigate the energy dissipation characteristic and impact behavior of rocking piers under free vibration. Research parameters include rocking interfaces (stiff or flexible), geometry of the column cross-section (circular or rectangular), aspect ratio of the columns, anchorage of prestressing tendons and scale effect. To validate the proposed theory, five columns were constructed and will be tested. A numerical process was proposed to simulate the rocking behavior of columns. Numerical analysis revealed that aspect ratio remarkably affects the rocking behavior, however, size effect and shape of cross section had no significant influence on the rocking behavior. Contrary to the instinct, anchored columns may have less damping due to the higher restoring forces that leads to larger acceleration and slower degradation in kinetic energy.
Reasonable Lateral Force Distributions on Isolated Structures
Authors: Tsai C. S. , Chen B. J. , Chiang T. C.
Published: May 2010

The base isolator can lengthen the natural period of a structure to reduce the transmission of energy from the ground into the structure. It has been recognized as an effective means by the engineering professions in earthquake prone regions. The design procedures of seismically isolated structures are mainly provided by the Uniform Building Code (UBC) published by the International Conference of Building Officials. The UBC code supplies a simple, statically equivalent design method where by displacements for an isolated structure are concentrated at the isolation level. Therefore, the superstructure nearly moves as a rigid body, and the design forces of elements above isolators are based on the behavior of isolators at the design displacement. However, in the UBC code, the distribution of inertial (or lateral) forces over the height of the superstructure above isolation has been found to be too conservative for most isolated structures. In view of this, two effortless and reasonable design formulae for lateral force distributions on isolated structures have been proposed in this paper. Results obtained from a full-scale isolated structure tested on the shaking table and numerical analyses of two additional examples verify the suitability of design formulae. It is demonstrated that proposed formulae can well predict lateral force distributions on isolated structures during earthquakes and that the lateral force distributions proposed by the UBC code are too conservative.
Shaking Table Tests of Full Scale Base-Isolated Structures
Authors: Tsai C. S. , Chen B. J. , Chiang T. C.
Published: May 2010

Conventional earthquake resistant designs depend on strengthen and ductility of the structural components to resist induced forces and to dissipate seismic energy. However, this can produce permanent damage to the joints as well as the larger interstory displacements. In recently years, many studies on structural control strategies and devices have been developed and applied in U. S. A., Europe, Japan, and New Zealand. The rubber bearing belongs to one kind of the earthquake-proof ideas of structural control technologies. The installation of rubber bearings can lengthen the natural period of a building and simultaneously reduce the earthquake-induced energy trying to impart to the building. They can reduce the magnitude of the earthquake-induced forces and consequently reduce damage to the structures and its contents, and reduce danger to its occupants. This paper is aimed at studying the mechanical behavior of the stirrup rubber bearings (SRB) and evaluating the feasibility of the buildings equipped with the stirrup rubber bearings. Furthermore, uniaxial, biaxial, and triaxial shaking table tests are conducted to study the seismic response of a full-scale three-story isolated steel structure. Experimental results indicate that the stirrup rubber bearings possess higher damping ratios at higher strains, and that the stirrup rubber bearings provide good protection for structures. It has been proved through the full-scale tests on shaking table that the stirrup rubber bearing is a very promising tool to enhance the seismic resistibility of structures.
Mission to Probe Venus's Curious Winds And Test Solar Sail for Propulsion
Authors: Normile Dennis
Published: May 2010

The Japan Aerospace Exploration Agency's Akatsuki mission, slated for launch on 18 May, will train four cameras at ultraviolet and infrared wavelengths on Venus to track clouds at different altitudes.
Population Analysis and Epidemiological Features of Inhibitor-Resistant-TEM-β-Lactamase-Producing
Escherichia coli
Isolates from both Community and Hospital Settings in Madrid, Spain
Authors: Martín Oihane , Valverde Aránzazu , Morosini María I. , Rodríguez-Domínguez Mario , Rodríguez-Baños Mercedes , Coque Teresa M. , Cantón Rafael , del Campo Rosa
Published: May 2010

Punctual mutations in the TEM-1 or TEM-2 gene may lead to inhibitor-resistant-TEM (IRT) β-lactamases with resistance to β-lactam-β-lactamase inhibitor combinations and susceptibility to cephalosporins. The aim of this work was to analyze the current epidemiology of IRT β-lactamases in contemporary clinical
Escherichia coli
. Isolates were prospectively collected in our hospital (2007 and 2008) from both outpatients (59.8%) and hospitalized patients (40.2%). The genetic relationships of the isolates were determined by XbaI pulsed-field gel electrophoresis, multilocus sequence typing, and phylogenetic group analysis. IRT genes were sequenced and located by hybridization, and the incompatibility group of the plasmids was determined. From a total of 3,556
E. coli
isolates recovered during the study period, 152 (4.3%) showed reduced susceptibility to amoxicillin-clavulanate, with 18 of them producing IRT enzymes (0.5%). These were mostly recovered from urine (77.8%). A high degree of IRT diversity was detected (TEM-30, -32, -33, -34, -36, -37, -40, and -54), and the isolates were clonally unrelated but were mostly associated with phylogenetic group B2 (55.5%). In 12 out of 16 (75%) isolates, the
bla
IRT
gene was plasmid located and transferred by conjugation in 9 of them, whereas chromosomal localization was demonstrated in 4 isolates (25%). The sizes of the plasmids ranged from 40 kb (IncN) to 100 kb (IncFII, IncFI/FIIA), and they showed different restriction patterns by restriction fragment length polymorphism analysis. Unlike extended-spectrum β-lactamase producers, the frequency of IRT producers remains low in both community and hospital settings, with most of them causing urinary tract infections. Although
bla
IRT
genes are mainly associated with plasmids, they can be also located in the chromosome. Despite this situation, clonal expansion and/or gene dispersion was not observed, denoting the independent emergence of these enzymes.
Group B Streptococcal Disease in Nonpregnant Patients: Emergence of Highly Resistant Strains of Serotype Ib in Taiwan in 2006 to 2008
Authors: Wang Ying-Hsiang , Su Lin-Hui , Hou Jiun-Nun , Yang Tsung-Han , Lin Tzou-Yien , Chu Chishih , Chiu Cheng-Hsun
Published: May 2010

Among the 228 group B
Streptococcus
(GBS) isolates recovered in 2006 to 2008, higher resistance to erythromycin (58.3%) and clindamycin (57.9%) was found in isolates with certain resistance phenotypes. Serotype Ib isolates (24.6%) were the second most prevalent serotype, next to serotype V (29.4%), and showed the highest resistance rates to erythromycin (91.0%) and clindamycin (82.1%).