bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Way to Autonomy: the Wireless‐interrogated and Self‐powered “Smart Patch” System
Authors: Galea Stephen C. , Van der Velden Stephen , Moss Scott , Powlesland Ian
Published: September 2009

Composite patches bonded to defective aircraft structures are a recognized cost‐effective repair or reinforcement technique for many types of structural problems, such as metallic cracking, repairing corrosion damage, and reducing fatigue strain at structural hot spots. However, certification concerns limit the application of composite bonded repairs in critical components. For certification and management of repairs to critical structure, the
smart patch
approach may be a useful approach from the airworthiness perspective in facilitating certification. The
smart patch
consists of a number of
in situ
sensors used to monitor the structural condition (health or well‐being) of the patch system and the status of the remaining damage in the parent structure. In summary the
smart patch
is an
in situ
structural health monitoring (SHM) technology applied to a composite bonded repaired structure. The demonstration of the
smart patch
on an operational aircraft offers an excellent vehicle to demonstrate autonomous SHM technology in an operational environment.

This article describes the development, evaluation, and implementation of the self‐powered wireless
smart patch
system, including issues such as system design, functionality and certification testing, and installation. This system had no primary power source (i.e., battery) and was powered instead by energy harvested from the local strain environment. It was wirelessly interrogated using a magnetic transceiver and employed piezoelectric elements for both powering and health monitoring functions. The article gives a brief overview of the various available power‐harvesting techniques considered and discusses several key issues that arose when designing and developing the self‐powered
smart patch
system, namely, (i) demand—power requirements, (ii) supply—energy generation from vibration or strain‐based sources, and (iii) conversion—issues and efficiencies associated with energy conversion from mechanical to electrical energies. Flight data from the system and lessons learned during the program are also presented.
Stanford Multiactuator–Receiver Transduction (
SMART
)
L
ayer Technology and Its Applications
Authors: Qing Xinlin P. , Beard Shawn J. , Kumar Amrita , Li Irene , Lin Mark , Chang Fu‐Kuo
Published: September 2009

This article summarizes the latest development efforts on the Stanford multiactuator‐receiver transduction (SMART) Layer technology used for structural health monitoring (SHM) for various applications. The SMART Layer consists of a network of thin piezoelectric sensors and actuators that are embedded into a dielectric film through an electronic circuit printing and lamination technique. The SMART Layer provides a viable and cost‐effective means for monitoring the health of structures of various configurations and sizes. The SMART Layer is very versatile, and by coupling it with appropriate diagnostic software and hardware, the same layer can be developed into a passive SHM system or an active SHM system. The passive and active systems are specifically designed for detection of impacts on a structure; diagnosis of cracks in metallic structures and impact damage and debonds in composite structures. Recent advances in techniques for fabricating the SMART Layers, as well as methods for integrating the layers into structures, are illustrated and examples are presented. The mechanical and electrical properties of the layer are highlighted, including the effect of embedment of the layer on the integrity of composite structures. Other practical issues, such as the environmental effect on the performance of the layer and the self‐diagnostics of the embedded network, are also discussed.
Design Principles for Civil Structures
Authors: Karbhari Vistasp M.
Published: September 2009

Although the term structural health monitoring (SHM) has gained prominence recently, its basis and motivation can be traced to the very earliest endeavors of mankind to conceptualize, construct, worry about deterioration, and then attempt to repair (or otherwise prolong the life) of a structure. Thus, it represents an attempt at deriving knowledge about the actual condition of a structure, or system, with the aim of not just knowing that its performance may have deteriorated, but rather to be able to assess remaining performance levels and life. In the case of civil structures where the expected service life is high (30–75+ years), where structures are repeated but are often one of a kind, and which are expected to continue performing in harsh and changing outdoor environments with low levels of inspection and maintenance, the needs of an SHM system are somewhat different from those used in aircraft and with machinery. The design principles are intrinsically related to the specifics of the structure including configuration and necessity of considering an outdoor environment.
Usage Management of Civil Structures
Authors: Miyamoto Ayaho
Published: September 2009

Bridge health monitoring using information technology and sensors is capable of providing more accurate knowledge of bridge performance than traditional strategies. This paper introduces a state of the art on not only an IT‐based bridge health monitoring system incorporated with the latest information technologies for lifetime management of existing bridges but also a data‐collecting system designed for bridge health monitoring.
Diagnosing Offshore Machines and Power Plants Using Vibration Methods
Authors: Grzadziela Andrzej
Published: September 2009

Currently, vibration methods of diagnosing machines and power plants are popular in offshore technology. They provide a lot of information about the dynamic behavior of rotating machines. This article presents the philosophy of operational decision according to measured vibration parameters. The main purpose of the tests is to determine the execution characteristics of vibration parameters in the functioning of main crankshaft or rotor revolution, loads, and operation time. Dissipation of energy in rotating machines is displayed as a torque, revolutions, temperature, gas flow, and vibration. Vibrations are connected to rotor imbalance, resonances, oversize of tolerated axis slope of shafts, abrade of blade tips with the inner roller, wear of axis and radial bearings, asymmetry of springiness and damping characteristics of rotors and their parts, and irregularity of gas‐flow forces. Emission of vibration brings a lot of information including opinion of the technical state of a machine. Measurements of vibration, their identification, classification, and mathematical analysis, including trend function, bring information on the actual technical state and allow predicting wear process of machines in the future. This article presents an application of the vibration method for diagnosing the following typical offshore equipment: reciprocating gas compressors, power plants equipped with gas turbines engines, and offshore tugs' main engines.
Landfills
Authors: Münnich Kai , Bauer Jan , Fricke Klaus
Published: September 2009

Landfills are very large and complex engineering structures, which have to be functionally stable as long as they represent a potential danger to the environment. From the multitude of potential risks, only fluid emissions and mechanical failure are considered in this article.

For landfill owners and operators, the need for monitoring of landfills is often only combined with the costs resulting from it. The experiences show that monitoring during the different stages of the lifespan of landfills is necessary to get an idea of the long‐term behavior of the landfill under the specific conditions of the site. This knowledge is important in view of prevention of uncontrolled emissions as well as large‐scale mechanical failure of the landfill structure. In this article, new measurement devices for monitoring leachate discharge and the deformation behavior of the landfill are presented, as well as the results of
in situ
measurements. The better spatiotemporal resolution allows a better understanding of the different processes occurring in the landfill.
SHMand Lifetime Management of Industrial Piping Systems
Authors: Schubert Frank , Frankenstein Bernd , Klesse Thomas , Kerkhof Klaus , Schuler Xaver , Friedmann Herbert , Henkel Fritz‐Otto , Wenzel Helmut
Published: September 2009

In this article, a structural health monitoring system for industrial piping systems is presented that combines global vibration monitoring and local guided wave monitoring within a multichannel and multipurpose measurement system. While vibration monitoring is able to characterize the global condition of the structure due to supports and dampers, the guided wave module is able to find small cracklike defects and corrosive material degradation in crucial error‐prone parts of the components. It can therefore be expected that a combination of the “global” and “local eye” will lead to a monitoring system with significantly increased performance and reliability. At the end of the article, the development of a joint decision support system embedded in an overall lifetime management for industrial piping systems is also described in detail.
Unmanned Aerial Vehicles
Authors: Buderath Matthias
Published: September 2009

Unmanned aerial vehicles (UAVs) is a new class of air vehicles for which many of the options in design are still fairly open. This also includes UAV health management and with this, structural health monitoring (SHM). This article presents a procedure by which SHM technology can be selected, which meets the requirements that have been set for the monitoring of the UAV system. Derivation of these requirements is made from a set of top‐level requirements of the UAVs. Aspects such as the need for decision support, operational cost reduction through SHM, as well as SHM certification is discussed. Much emphasis is placed on the issue of integrating SHM into the UAV health management system. This is discussed along the needs of loads and damage monitoring and how this can be linked with Open Systems Architecture for Condition‐Based Maintenance (OSA‐CBM). This article presents a procedure along which SHM technology can be selected, which allows to match the requirements that have been set for the UAV system to be monitored.
Comparative Vacuum Monitoring (
CVM
™)
Authors: Barton Duncan P.
Published: September 2009

Comparative Vacuum Monitoring, or ™CVM, relies on the fact that a vacuum maintained in a small volume is extremely sensitive to leaks. The technology uses this basic phenomenon to accurately monitor surface defects (cracks in metals and disbond or delamination in composite materials) in structures. As a vacuum cannot exist naturally on Earth, the system enjoys a number of self‐checking characteristics as a result. The system can be monitored continuously, in real time, or on a periodic basis as required by the structural health management protocol with existing instrumentation. The technology has been applied in laboratory applications through to in‐service trials in a range of industries including aerospace and automotive.
Monitoring of Aircraft Engines
Authors: Kadirkamanathan Visakan , Fleming Peter
Published: September 2009

Aircraft engines are highly reliable complex systems with enhanced safety requirements. Monitoring engine component degradations to avoid the high flight shut down and repair costs is vital for the aircraft manufacturers and operators in the current business model. Monitoring systems are required to perform diagnosis of developing faults and prognosis to plan maintenance actions. The common engine faults are due to the mechanical components requiring vibration analysis and oil and debris monitoring, as well as the gas path component faults requiring efficiency and other performance parameter monitoring. For vibration monitoring, spectral signatures are used for detecting changes to the normal engine operation. On the other hand, prognosis is often based on trending the gas path performance parameters. The use of intelligent systems methods such as case‐based reasoning, neural networks, and fuzzy systems has proved popular because of the lack of precise knowledge about the behavior of a complex system like the aircraft engine. Where accurate models are available, model‐based methods such as the Kalman filter, observers and, where dynamic data are available, system identification approaches have found application. Often, information from more than one analysis is integrated in decision making. The grid computing architecture‐based distributed Aircraft Maintenance Environment (DAME) project shows the future direction in which aircraft engine monitoring is heading.
Design Benefits in Aeronautics Resulting from
SHM
Authors: Schmidt Hans‐Juergen , Schmidt‐Brandecker Bianka
Published: September 2009

The current FAA (Federal Aviation Administration) and CS (Certification Standard) damage tolerance requirements and their interpretation impact the design and the weight of large areas of civil transport aircraft made of metal. Examples for these areas are specific stiffened panels of the fuselage and the wing. The application of structural health monitoring (SHM) in these areas allows inspections of internal and external structures at small intervals. This improved information compared with the results of traditional inspections, especially about the internal structure, allows a less conservative interpretation of the damage scenarios used in the so‐called damage tolerance analysis. The resulting benefits can be used either for reduction of the maintenance requirements, for an optimization of the design to achieve weight savings or for a combination of both benefits.

This article deals with the major aspects of SHM application for improving the design efficiency of metallic fuselage structures of a large civil transport aircraft. The presentation discusses major details such as the general philosophy, possible sensor application, and requirements about the durability of the integrated SHM system. General examples using typical fuselage design features and synthetic operational stresses of the biaxial loaded panels in different fuselage areas are presented. Parametric damage tolerance analyses using fracture mechanics methods show the possible weight savings or the possible reduction of the maintenance program for the defined assumptions, e.g., material of structure, location of sensors and detectable damage size.
Design, Analysis, andSHMof Bonded Composite Repair and Substructure
Authors: Soutis Constantinos , Ihn Jeong‐Beom
Published: September 2009

The behavior of bonded patch repaired composite laminates loaded in uniaxial in‐plane tension or compression is examined. A nonlinear stress analysis is performed on a double‐lap joint to identify critical joint parameters and design an efficient external patch repair. It is found that oversized patches not only increase the structure's weight but also increase the stress concentrations in the repaired region, which can cause premature failure. Reducing the patch thickness near the edges of the overlap and increasing the local adhesive thickness decreases the stress concentration in both shear and peel stresses. A three‐dimensional finite element analysis is then performed to determine the stresses in the optimum repaired configuration and used with a stress‐based failure criterion to predict the ultimate failure load. Experimental measurements show that carefully designed bonded patch repairs can recover up to 80% of the undamaged laminate strength. The integrity of the bonded repair in terms of crack growth underneath the patch, which can arise from fatigue loading, impact, improper surface preparation, or environmental exposures, can be successfully monitored by inserting two smart layers (an embedded network of piezoelectric actuators/sensors) into the repair patch.
Aircraft Structural Diagnostic and Prognostic Health Monitoring for Corrosion Prevention and Control
Authors: Galea Stephen C. , Trueman Tony , Davidson Len , Trathen Peter , Hinton Bruce , Wilson Alan , Muster Tim , Cole Ivan , Corrigan Penny , Price Don
Published: September 2009

Structural health monitoring (SHM) systems that provide diagnostic and prognostic information on corrosion‐related damage will enable maintainers and operators of aircraft to manage the prevention and control of corrosion in aircraft structural components on a condition basis rather than on elapsed number of (flying) hours. This article discusses the key elements associated with such a system, viz., corrosion sensors, environment monitors, corrosion‐prediction models, system architecture, and maintenance decisions. The article gives a brief overview of current demonstrators. It is envisaged that SHM systems will assist aircraft maintainers and operators in making decisions as to whether corroded components should be repaired, replaced, or may be treated and left in place until a more convenient inspection period.
Experience with Health and Usage Monitoring Systems in Helicopters
Authors: Le Dy Dinh
Published: September 2009

Advisory Circular 29‐2 C, Section MG‐15, Airworthiness Approval of Rotorcraft Health and Usage Monitoring System (HUMS), provides guidance for achieving airworthiness approval for installation, credit validation, and instructions for continued airworthiness for a full range of HUMS applications. The state‐of‐the‐art HUMS and recent advancements including usage monitoring, flight regime recognition, fault, and crack detection technologies have begun to allow the use of HUMS for the condition‐based maintenance or maintenance credits. “Maintenance credit” means to give approval to a HUMS application that adds to, replaces, or intervenes in industry‐accepted maintenance practices or flight operations.

Additionally, the future use of HUMS can eventually allow the fatigue life of rotorcraft components to be extended or the life‐limited components to be removed before its fatigue life is fully consumed. Therefore, HUMS technologies and their applications can be used to achieve the safety goal, maintain continued airworthiness, and improve operating costs of rotorcraft.

This article provides the Federal Aviation Administration (FAA) perspective of how HUMS are being used or may be used in rotorcraft to address safety and continued airworthiness issues. This article also describes a few FAA‐critical research efforts to achieve the full implementation of HUMS for usage credits.
Validation ofSHMSensors in AirbusA380 Full‐Scale Fatigue Test
Authors: Paget Christophe , Speckmann Holger , Krichel Thomas , Eichelbaum Frank
Published: September 2009

IABG is responsible for conducting the A380 full‐scale fatigue test at its company site in Dresden, Germany. The A380 full‐scale fatigue test setup has been erected by IABG in 2004/2005 and the test was started on September 1, 2005. Airbus has introduced a number of Structural health monitoring (SHM) means into the test specimen for validation of innovative shm technologies.
Aerospace Applications ofSMARTLayer Technology
Authors: Qing Xinlin P. , Beard Shawn J. , Ikegami Roy , Chang Fu‐Kuo , Boller Christian
Published: September 2009

Structural health monitoring (SHM) is increasingly being considered by the aerospace industry as a new and innovative technique to enhance the safety and reliability of structures, maximize structure operational efficiency, and minimize their operational cost. This article summarizes the latest developments in SHM systems based on SMART Layer technology in aerospace‐related applications. The systems consist of three major components: sensor/actuator network, integrated hardware, and diagnostic software. Two types of SHM systems in terms of their applications are introduced: one is the onboard system and the other is the off‐board system. The onboard SHM system has all components integrated with the host structures, and data can be automatically taken and processed. However, the off‐board system requires only the sensor network to be integrated with the structures, while the hardware and software are detached from the structures and form a portable stand‐alone unit. Data are taken only when the unit is reconnected to the sensor network. A variety of applications of both onboard and off‐board systems are discussed, including monitoring damage in composite pressure vessels and large composite barrels, cracks in the pipes of liquid rocket engines, multisite damage in riveted joints, bondlines in composite repairs, detection of impacts on the thermal protection systems (TPS) of space vehicles, and monitoring composite rocket motor cases.
Long‐Term Monitoring of Dynamic Loads on the Brandenburg Gate
Authors: Rücker Werner
Published: September 2009

The reason for a certain amount of damage at the well‐known national monument “Brandenburg gate” should be investigated and clarified. In order to get sufficient information of the current static and dynamic structural behavior, a modal analysis of the gate has been carried out. The impacts on the gate because of railroad and road traffic, construction work, and special events like the “love parade” have been measured and investigated by using a permanently operating monitoring system. With the help of modal analysis and results from the condition monitoring system, the reason for the damage could be identified and threshold values for further impact to the structure could be defined. The results of the investigation serve also as a basis for the development of the best technical and economical rehabilitation measures.
Development of a Monitoring System for a Long‐span Cantilever Truss Bridge
Authors: Catbas F. Necati , Aktan A. Emin
Published: September 2009

Structural health monitoring (SHM) is a paradigm that enables an integrated systems approach for a reliable measurement‐based understanding of the loading environment of major bridges, and how their structural systems carry their loads as they operate and fulfill their functions. For long‐span bridges, some of the most pressing challenges are solving performance problems that are related to objectionable movements and geometry changes, displacements, vibrations, and visible signs of aging. In this study, an overview of a comprehensive monitoring project of the longest cantilever truss bridge in the United States is presented. A critical objective of this study is the development and demonstration of a complete SHM framework with Internet‐based real‐time monitoring modules, various sensors, data‐acquisition systems, data management and communication protocols, and data analysis methods. The monitoring of this long‐span bridge incorporated various intermittent and long‐term monitoring studies on the bridge to explore several operational, maintenance, and safety issues. This study also presents the need for an integrated systems approach to technology development and for the leveraging of technology in order to make a difference in how we manage major bridges. Integrated systems approach requires that we correctly identify, measure, understand, and then incorporate, in any management decision, the interactions between natural, sociotechnical, and constructed systems that govern the performance of all infrastructure components and systems.
Modular Architecture of
SHM
System for Cable‐Supported Bridges
Authors: Wong Kai‐Yuen , Ni Yi‐Qing
Published: September 2009

Structural health monitoring system for cable‐supported bridges has been implemented and operated in Hong Kong for a decade. The bridge health monitoring system in Hong Kong is referred to as
wind and structural health monitoring system (WASHMS)
. The WASHMS, which is devised to monitor structural condition and evaluate structural degradation as it occurs rather than to detect structural failures, is composed of six modules, namely, module 1—sensory system, module 2—data acquisition and transmission system (DA&TS), module 3—data processing and control system, module 4—structural health evaluation system, module 5—structural health data management system, and module 6—inspection and maintenance system. This article provides a description of the function of individual modular systems and the operation of the integrated modular systems.
Bridge Monitoring in Japan
Authors: Abe Masato , Fujino Yozo
Published: September 2009

The development of health monitoring of bridges in Japan is reviewed from geographical and socioeconomical background to specific applications. The backgrounds are categorized as (i) environment and natural disasters, (ii) stock management, and (iii) risk and safety. In other words, severe environment, limited resource for maintenance, and increased requirement for safety are the key factors for development of structural health monitoring.

To understand the environment and natural disasters, environment and loading have been monitored at various bridges for decades. Although these measurements were intended to measure loading and not necessarily to measure structural condition, analyses indicate usefulness of these measurements for evaluation of structural integrity.

For improvement of stock management, monitoring technologies for common workhorse bridges, preventive maintenance, and improvement in routine inspection are being developed and applied.

For improved safety, several monitoring technologies for risk and vulnerability have been developed and implemented, especially for railway bridges. When a threatening failure mode can be identified, a specific monitoring device is selected for risk management. Also, vulnerability monitoring to evaluate integrity of structures is introduced. This technique can be used to compare relative safety, and prioritize the action for improvement. Structural health monitoring technologies in this domain can be categorized into (i) microscopic monitoring, where damage detection and localization are the main interests; and (ii) macroscopic monitoring, where holistic structural integrity and its comparison are the main focus. The former is the conventional mainstream of structural health monitoring and is advancing steadily, whereas the latter is recently attracting interest, especially from the practical point of view to connect health monitoring and existing inspection methodology.
Continuous Vibration Monitoring and Progressive Damage Testing on the
Z
24 Bridge
Authors: Reynders Edwin , Roeck Guido De
Published: September 2009

The Z24 bridge project is unique in the sense that a long‐term continuous monitoring test is combined with realistic short‐term progressive damage tests on a full‐scale bridge. The measurement data have been presented as a benchmark test for system identification methods for operational modal analysis as well as a benchmark test for algorithms for structural health monitoring and damage identification. This article contains a description of the bridge tests as well as a literature review of results obtained with the measurement data.
Condition Compensation in Frequency Analyses—a Basis for Damage Detection
Authors: Veit‐Egerer Robert
Published: September 2009

Recent publications have raised doubts as to whether damage in structures can be detected by the application of frequency analyses. In fact, very often, temperature changes show larger reactions in spectra than any smaller damage. Beside temperature, other environmental influences such as radiation from sunshine create changes in the structural systems that have to be considered.
Multiple‐Model Structural Identification
Authors: Smith Ian F. C.
Published: September 2009

Complex structures create important challenges in structural health monitoring. Direct measurement of all phenomena is not possible. Modeling of behavior is rarely accurate. Measurement systems also have errors that may compensate modeling errors so that wrong models are identified. Generation and subsequent filtering of candidate models using rationally defined error thresholds provides systematic support to structural identification. Five orders of identification are described. At the lowest level (order 0), the model used for design is calibrated with measurements. At the highest level (order 4), candidate models are generated using the criterion that the differences between measurements and predictions fall below a threshold value that is fixed probabilistically. At identification order 4, candidate models are then filtered using data‐mining techniques and the addition of specially targeted measurement data. The best order to choose depends on available information and resources, as well as the level of decision support required for specific infrastructure‐management tasks.
SHM
Actions on the
H
oly
S
hroud
C
hapel in
T
orino
Authors: De Stefano Alessandro
Published: September 2009

Architectural heritage is a resource and a fundamental part of the cultural European background; it also causes concern due to the huge investment needed to maintain it, or even to repair it, after environmental injuries. Dynamic testing is a fundamental tool to perform a general, low‐cost, recurring or continuous on‐line survey on the structural whole body. A study on the Holy Shroud Chapel in Torino (Italy) is reported as a validation of the monitoring techniques adopted at present on ancient buildings, although the refinement of the model updating procedure is not yet concluded.
Condamine Floating Dock,
M
onaco
Authors: Ortega Luis M. , Floriano Manuel A.
Published: September 2009

This article describes the monitoring carried out on the floating dock for the enlargement of the Port of Monaco. This dock is a floating caisson 352.7‐m long and weighing 167 000 t, which was built in Algeciras Bay and towed by sea to its destination Monaco. The purpose of the monitoring was to control the bending forces suffered by the caisson while being transported by sea from its building location to its final destination. This enabled meeting the requirements of the owner (and of the insurance companies involved) to experimentally check that such bending forces did not exceed those outlined in the project for this operation, thus guaranteeing that the dock had not suffered any damage during transport.

A complete description of the instrumentation used is given, which includes the measurement of pressures, rotations, strains, and temperatures. The main results obtained are discussed.
Soil–Structure Interaction and Seismic Effects
Authors: Achs Günther
Published: September 2009

In recent years, considerable research and development in all fields of earthquake engineering was conducted. In particular, the reassessment of the seismic risk in countries with former low seismicity has brought about considerable changes in civil engineering.

In general, monitoring of soil–structure interaction effects is something that needs to be intensified in the future. As there is very poor current practice on this topic, this article should indicate a perspective view on possible applications.

For a realistic seismic assessment of structures, it is often necessary to use methodologies that regard the influence of the subsoil on one hand and can assess the real bearing capacity of the structure on the other hand. These two major issues are discussed within this article. In the first part of this article, a brief overview of the theoretical methodology of soil–structure interaction techniques is given, which should cover the needs of realistic modeling in earthquake engineering. The second part should mainly describe an approach for the experimentally based seismic assessment of structures, demonstrated at a practical example. Finally, the last part of the article should give an overview of seismic effects in general.
System Identification for Soil—Structure Interaction
Authors: Safak Erdal
Published: September 2009

The termsoil–structure interaction(SSI) refers to the influence of the deformations of the ground on the dynamic response of a structure. It is an important phenomenon of seismic excitations. If a structure is founded on rock, it is reasonable to assume that the ground does not deform and the structure is rigidly fixed at the base. If it is founded on soil, however, the flexibility of soil will cause the foundation of the structure to have translational and rotational motions when it is vibrating. SSI can significantly alter the vibration characteristics of a building and, consequently, the characteristics of recorded motions from that building.

The dominant frequency recorded in a structure with SSI is always smaller than that without SSI. When the foundation motion is taken as the input, a structure with SSI is a noncausal system because of the coupling between the motions of the foundation and the superstructure. For building‐type structures, the presence of SSI can be detected by comparing the dominant frequency of the top floor motions with the dominant frequency of the foundation‐to‐top floor transfer function. The dominant frequency of the top floor motions corresponds to the frequency with SSI, whereas the dominant frequency of the foundation‐to‐top floor transfer function corresponds to the frequency if the building were fixed‐based. If these two frequencies are equal, there is no SSI. The presence of SSI can also be detected by investigating the causality of the building's foundation‐to‐roof impulse response function. For causal systems, the amplitudes of the impulse response function at negative times are zero, whereas for noncausal systems they are comparable with those at positive times.
Environmental Factors Derived from Satellite Data of
J
ava,
I
ndonesia
Authors: Teilen‐Willige Barbara , Mulyasari Sule Farah , Wenzel Helmut
Published: September 2009

Indonesia is characterized by a very high level of natural hazards such as seismic and volcanic activities and it is one of the main tsunami‐prone areas. Natural hazards (earthquakes, flooding, volcanism, etc.) determine life conditions of the population to a large extent: several active volcanoes have the potential to seriously threaten adjacent communities. Extended flooding has led to severe problems. Therefore, various types of vulnerability assessment methodologies, software, and tools available for the state, local governments, and local stake holders have to be investigated. In the fields of awareness, preparedness, and mitigation of natural hazards, a multidisciplinary integration of different methods and data has the greatest potential for substantial progress. In the scope of this study, the use of remote sensing and geographic information systems (GIS) is examined as contribution to a multirisk database. Satellite imageries and digital elevation data form the basic data stock. Digital image processing methods are used to enhance satellite data in order to contribute to the investigation of environmental conditions and of natural hazards. LANDSAT enhanced thematic mapper (ETM) imageries merged with digitally processed digital elevation data clearly indicate areas that might be prone to flooding in cases of extreme weather events, catastrophic tsunamis, or storm surge. Subsurface structures such as fault zones can be derived by geomorphologic analysis (drainage pattern) and the identification of linear tonal anomalies on the imageries. Some factors influencing volcanic activity can be derived from satellite imageries and morphometric maps such as slope steepness.
Risk Monitoring of Aircraft Fatigue Damage Evolution at Critical Locations
Authors: Shiao Michael
Published: September 2009

Fatigue damage detection and damage evolution monitoring are critical issues for the continued operational safety of aircraft. This article describes key technical elements, including probabilistic methods for risk monitoring of aircraft fatigue damage evolution at critical locations using either on‐board sensors or off‐board nondestructive inspection methods. Although the technical issues regarding risk monitoring are different between on‐board and off‐board structural health monitoring (SHM), they share many technical elements, such as SHM system sensitivity, inspection dependency and frequency, repair quality, damage evolution characterization, uncertainty quantification, and risk forecasting and updating for prognosis. A probabilistic framework and its associated methodologies, including the key technical elements, are described and discussed. The probabilistic methodologies consist of specialized probabilistic algorithms considering maintenance‐related uncertainties, as well as inspection dependency, characterization of fatigue damage evolution, and a Bayesian updating approach to update prior knowledge using damage state information obtained through inspections.
Value Assessment Approaches for Structural Life Management
Authors: Medina Enrique A. , Aldrin John C.
Published: September 2009

This article presents an overview of the basic principles of value assessment for structural health monitoring (SHM) technology as part of life‐cycle management of aerospace structures. By evaluating and optimizing trade‐offs among reliability, availability, and life‐cycle costs, value assessment methods can help decide whether and how SHM technologies should be implemented as part of structural life management in conjunction with nondestructive evaluation (NDE) techniques. We review various methods of value assessment, including cost‐benefit analysis and multicriteria optimization. We describe several deterministic and probabilistic modeling tools available in the market and present several application examples. These analyses use a method for estimating total life‐cycle cost of various maintenance options including SHM and compare these options based on costs and system reliability benefits. We also present several examples that use a value assessment method based on multicriteria optimization and show how these tools enable optimization of trade‐offs among various reliability and cost objectives of the hybrid NDE‐SHM (nondestructive evaluation/structural health monitoring) life management design problem. Finally, we discuss the need for improved data to enable better life management strategies.
Military Aircraft
Authors: Derriso Mark M. , Olson Steven E. , DeSimio Martin P.
Published: September 2009

Structural health monitoring (SHM) has the potential to reduce cost, increase availability, and maintain safety of current and future military aircraft. Ideally, SHM systems would be an integral part of integrated systems health management (ISHM) technologies. These ISHM methods would be able to determine the health of an entire vehicle based on combined assessments of various vehicle subsystems, such as the vehicle structure. To date, however, few fielded SHM systems exist for aerospace structures. There must be both a business justification to field such systems as well as technical feasibility. For at least certain aerospace applications, a strong business case can be made for implementing such a system. The SHM community also has made considerable efforts to address the technical challenges. Assuming that the business and technical challenges can be overcome, various near‐term and far‐term aerospace applications can be identified.
Fatigue Monitoring in Nuclear Power Plants
Authors: Kleinöder Wilhelm , Pöckl Christian
Published: September 2009

During design phase, stress and fatigue analyses are made in order to design safety‐related components of the pressure‐retaining boundary in nuclear power plants. The design transients are based on the planned operation procedures for the different nuclear primary and auxiliary systems. These design transients are always assumed conservatively with respect to the temperature differences and the expected thermal gradients.

A measurement program carried out in a German nuclear power plant in 1982 showed that the real operating conditions of the plant partly differed from the assumptions and predictions. It was quite clear that this insight will also have a significant influence on the fatigue calculations made so far; however, more detailed analyses on the basis of the measured data showed that fatigue limits were not exceeded. This experience also revealed the big potential of making fatigue analyses on the basis of measured data.

Within the following years, the first developments were made for the permanent monitoring of component fatigue. Meanwhile, fatigue monitoring plays an important role in structural health monitoring in nuclear power plants. Particularly for utilities, which are planning lifetime extension for their plants, it is an invaluable advantage if they have measured data of the real operating behavior of their systems and components available. With such data, the current real fatigue usage factor can be easily calculated for most cases and therefore an extrapolation for future development can be made.

This article shows the development of such a fatigue monitoring system till the current state and deals with the benefits for the units that have implemented such systems. It also describes the studies that are necessary for the definition of the locations to be monitored. Furthermore, the current state of the technical devices used for monitoring is described. These include the mechanical components as well as the electronic systems needed for the acquisition of data. It is also necessary to mention the procedures used for evaluation of the data. Different methodologies from cycle counting to fatigue analyses based on monitored data are described and examples are given. Also, existing alternative fatigue monitoring systems from other engineering companies and manufacturers are briefly outlined. Finally, new developments that may come up in the future are also discussed.
Wet‐Spun Biodegradable Fibers on Conducting Platforms: Novel Architectures for Muscle Regeneration
Authors: Razal Joselito M. , Kita Magdalena , Quigley Anita F. , Kennedy Elizabeth , Moulton Simon E. , Kapsa Robert M. I. , Clark Graeme M. , Wallace Gordon G.
Published: September 2009

Novel biosynthetic platforms supporting ex vivo growth of partially differentiated muscle cells in an aligned linear orientation that is consistent with the structural requirements of muscle tissue are described. These platforms consist of biodegradable polymer fibers spatially aligned on a conducting polymer substrate. Long multinucleated myotubes are formed from differentiation of adherent myoblasts, which align longitudinally to the fiber axis to form linear cell‐seeded biosynthetic fiber constructs. The biodegradable polymer fibers bearing undifferentiated myoblasts can be detached from the substrate following culture. The ability to remove the muscle cell‐seeded polymer fibers when required provides the means to use the biodegradable fibers as linear muscle‐seeded scaffold components suitable for in vivo implantation into muscle. These fibers are shown to promote differentiation of muscle cells in a highly organized linear unbranched format in vitro and thereby potentially facilitate more stable integration into recipient tissue, providing structural support and mechanical protection for the donor cells. In addition, the conducting substrate on which the fibers are placed provides the potential to develop electrical stimulation paradigms for optimizing the ex vivo growth and synchronization of muscle cells on the biodegradable fibers prior to implantation into diseased or damaged muscle tissue.
Enhancing molecular discovery using descriptor‐free rearrangement clustering techniques for sparse data sets
Authors: DiMaggio Peter A. , McAllister Scott R. , Floudas Christodoulos A. , Feng Xiao‐Jiang , Li Genyuan , Rabinowitz Joshua D. , Rabitz Herschel A.
Published: September 2009

This article presents a descriptor‐free method for estimating library compounds with desired properties from synthesizing and assaying minimal library space. The method works by identifying the optimal substituent ordering (i.e., the optimal encoding integer assignment to each functional group on every substituent site of molecular scaffold) based on a global pairwise difference metric intended to capture smoothness of the compound library. The reordering can be accomplished via a (i) mixed‐integer linear programming (MILP) model, (ii) genetic algorithm based approach, or (iii) heuristic approach. We present performance comparisons between these techniques as well as an independent analysis of characteristics of the MILP model. Two sparsely sampled data matrices provided by Pfizer are analyzed to validate the proposed approach and we show that the rearrangement of these matrices leads to regular property landscapes which enable reliable property estimation/interpolation over the full library space. An iterative strategy for compound synthesis is also introduced that utilizes the results of the reordered data to direct the synthesis toward desirable compounds. We demonstrate in a simulated experiment using held out subsets of the data that the proposed iterative technique is effective in identifying compounds with desired physical properties. © 2009 American Institute of Chemical Engineers AIChE J, 2010
The perception of fragrance mixtures: A comparison of odor intensity models
Authors: Teixeira Miguel A. , Rodríguez Oscar , Rodrigues Alírio E.
Published: September 2009

A comparison of two psychophysical odor intensity models and their effect on the prediction of the odor character for perfume mixtures is presented. The odor value (OV) and Power‐Law models were applied together with previously developed perfumery ternary diagram (PTD®) and perfumery quaternary diagram (PQD) methodologies to map the perceived smell of quaternary and quinary fragrance mixtures. A diffusion model was used to simulate the evolution of liquid and headspace concentrations. The evaporation of perfumes starts with a fast ethanol release, then the diffusion of the fragrant components. The composition paths were predicted through the evaporation lines plotted in the PQD. The two odor intensity models present differences in the initial perfume impact, but after some time tend to similar profiles. The Power‐Law predicted higher ethanol intensities than the OV model, due to its exponent. Introducing water in perfume formulation fixes ethanol in the solution, thus reducing alcohol perception. © 2009 American Institute of Chemical Engineers AIChE J, 2010
G72 influences longitudinal change in frontal lobe volume in schizophrenia
Authors: Hartz Sarah M. , Ho Beng‐Choon , Andreasen Nancy C. , Librant Amy , Rudd Danielle , Epping Eric A. , Wassink Thomas H.
Published: September 2009

Schizophrenia is a neurodevelopmental psychiatric disorder characterized by a variety of structural brain abnormalities that appear to progress across the course of illness. Schizophrenia also is highly heritable, and one gene that has emerged as a possible susceptibility factor is G72. G72 influences brain development and activity by an as‐yet unclear mechanism, and multiple studies have reported associations between G72 and schizophrenia. We were interested in linking these domains of investigation by determining whether G72 also influences the rate of longitudinal structural brain changes in individuals with schizophrenia. As part of the Iowa Longitudinal Study of Recent Onset Psychoses, we genotyped four G72 polymorphisms previously associated with schizophrenia in 110 subjects with schizophrenia or schizoaffective disorder from whom we had obtained two brain MRI scans an average of 3 years apart. The four polymorphisms captured three haplotypes, one of which was strongly associated with an increased rate of frontal lobe volume decrement. This same haplotype was also associated with more severe psychotic symptoms at the time of the second scan. These data thus suggest that variation in G72 modulates the progressive brain changes that characterize schizophrenia. © 2009 Wiley‐Liss, Inc.