Academic literature on the topic 'Operational mode shape'
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Journal articles on the topic "Operational mode shape"
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PARLOO, E., P. VERBOVEN>, P. GUILLAUME, and M. VAN OVERMEIRE. "SENSITIVITY-BASED OPERATIONAL MODE SHAPE NORMALISATION." Mechanical Systems and Signal Processing 16, no. 5 (September 2002): 757–67. http://dx.doi.org/10.1006/mssp.2002.1498.
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De Sitter, Gert, Patrick Guillaume, Steve Vanlanduit, and Christof Devriendt. "Operational Acoustic Modal Analysis: Sensitivity-Based Mode Shape Normalisation." Acta Acustica united with Acustica 94, no. 4 (July 1, 2008): 580–87. http://dx.doi.org/10.3813/aaa.918067.
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Parloo, E., B. Cauberghe, F. Benedettini, R. Alaggio, and P. Guillaume. "Sensitivity-based operational mode shape normalisation: Application to a bridge." Mechanical Systems and Signal Processing 19, no. 1 (January 2005): 43–55. http://dx.doi.org/10.1016/j.ymssp.2004.03.009.
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Brincker, Rune. "Some Elements of Operational Modal Analysis." Shock and Vibration 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/325839.
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This paper gives an overview of the main components of operational modal analysis (OMA) and can serve as a tutorial for research oriented OMA applications. The paper gives a short introduction to the modeling of random responses and to the transforms often used in OMA such as the Fourier series, the Fourier integral, the Laplace transform, and the Z-transform. Then the paper introduces the spectral density matrix of the random responses and presents the theoretical solutions for correlation function and spectral density matrix under white noise loading. Some important guidelines for testing are mentioned and the most common techniques for signal processing of the operating signals are presented. The algorithms of some of the commonly used time domain and frequency domain identification techniques are presented and finally some issues are discussed such as mode shape scaling, and mode shape expansion. The different techniques are illustrated on the difficult case of identifying the three first closely spaced modes of the Heritage Court Tower building.
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Rahul, R., Rohit Rajpal, Sai Aditya Raman Kuchibhatla, and K. V. Gangadharan. "Sensor Fusion for Operational Mode Shape Analysis of Multi DoF Systems." Materials Today: Proceedings 5, no. 11 (2018): 24871–79. http://dx.doi.org/10.1016/j.matpr.2018.10.286.
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Quintanar-Guzmán, Serket, Somasundar Kannan, Adriana Aguilera-González, Miguel A. Olivares-Mendez, and Holger Voos. "Operational space control of a lightweight robotic arm actuated by shape memory alloy wires: A comparative study." Journal of Intelligent Material Systems and Structures 30, no. 9 (August 25, 2017): 1368–84. http://dx.doi.org/10.1177/1045389x17721050.
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This article presents the design and control of a two-link lightweight robotic arm using shape memory alloy wires as actuators. Both a single-wire actuated system and an antagonistic configuration system are tested in open and closed loops. The mathematical model of the shape memory alloy wire, as well as the kinematics and dynamics of the robotic arm, are presented. The operational space control of the robotic arm is performed using a joint space control in the inner loop and closed-loop inverse kinematics in the outer loop. In order to choose the best joint space control approach, a comparative study of four different control approaches (proportional derivative, sliding mode, adaptive, and adaptive sliding mode control) is carried out for the proposed model. From this comparative analysis, the adaptive controller was chosen to perform operational space control. This control helps us to perform accurate positioning of the end-effector of shape memory alloy wire–based robotic arm. The complete operational space control was successfully tested through simulation studies performing position reference tracking in the end-effector space. Through simulation studies, the proposed control solution is successfully verified to control the hysteretic robotic arm.
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Rovšček, Domen, Janko Slavič, and Miha Boltežar. "Operational mode-shape normalisation with a structural modification for small and light structures." Mechanical Systems and Signal Processing 42, no. 1-2 (January 2014): 1–13. http://dx.doi.org/10.1016/j.ymssp.2013.08.019.
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Tao, C., Y. Daren, and B. Wen. "Distributed parameter control arithmetic for an axisymmetrical dual-mode scramjet." Aeronautical Journal 112, no. 1135 (September 2008): 557–65. http://dx.doi.org/10.1017/s0001924000002517.
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AbstractDual-mode scramjet is one of the candidates for hypersonic flight propulsion system which will be used in wide range of flight Mach numbers from 4 to 12 or higher, wherein dual-mode scramjet should be well designed to be suitable for subsonic/supersonic combustion operation according to the flight conditions. Therefore this system is required to operate in a finite number of operational modes that necessitate robust, stable, and smooth transitions between them by which selective operability of supersonic/subsonic combustion modes and efficient combustor operation in these modes may be realised. A key issue in making mode transition efficient and stable is mode transition control. The major problem in mode transition control is the handling of the various flow and combustion coupling effects of dual-mode scramjet whose physical states are spatially coupled and whose governing equations are partial differential equations. Involving these distributed parameter issues, our basic idea is using the shape control theory to study the control problems of mode transition for dual-mode scramjet with the aim of achieving the desirable design properties and increasing control reliabilities. This specific approach is motivated by the promise of novel techniques in control theory developed in recent years. Concrete control arithmetic of this approach, such as shape control model, sensitivity analysis and gradient-based optimisation procedure, are given in this paper. Simulation results for an axisymmetric, wall-injection dual-mode scramjet show the feasibility and validity of the method.
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Tozkoparan, Ã.-mer Anıl, Osman Taha Sen, and Rajendra Singh. "Case study: Identification of brake squeal source mechanism through experimental and computational approaches." Noise Control Engineering Journal 68, no. 1 (January 20, 2020): 21–37. http://dx.doi.org/10.3397/1/37682.
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In this case study, mechanism leading to squeal noise in an automotive disc brake system is investigated with focus on systematic laboratory experiments and associated computational models. First, experimental modal analyses are conducted on the brake corner assembly components, and the natural frequencies and corresponding mode shapes are obtained. Second, finite element models of same components are developed, updated and validated by comparing predicted modal characteristics with those measured. Third, a controlled laboratory experiment is designed, constructed and operated in a semi-anechoic room. Experiments are conducted at many operational disc speeds and brake line pressures, and acceleration on the caliper and sound pressure are measured. Squeal events at distinct frequencies are successfully identified in the experiments. Fourth, a comprehensive computational model of the brake corner assembly is constructed using validated component models, and squeal investigation is then conducted through complex eigenvalue analyses while mimicking the operational conditions of experiments. The system model yields unstable frequencies at several operational conditions. It is observed that experimentally detected squeal frequencies match well with predicted unstable frequencies. Finally, operational deflection shape measurements on the caliper are also carried out during squeal events, and the predictions are found to be similar to those measured. In conclusion, the squeal generation mechanism of the brake system is understood from the perspective of frictioninduced modal coupling, and an experimentally validated computational model of the brake system is successfully developed that may be used to find solutions to mitigate squeal.
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Mironov, Aleksey, Pavel Doronkin, Aleksander Priklonsky, and Igor Kabashkin. "Condition Monitoring Of Operating Pipelines With Operational Modal Analysis Application." Transport and Telecommunication Journal 16, no. 4 (December 1, 2015): 305–19. http://dx.doi.org/10.1515/ttj-2015-0028.
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Abstract In the petroleum, natural gas and petrochemical industries, great attention is being paid to safety, reliability and maintainability of equipment. There are a number of technologies to monitor, control, and maintain gas, oil, water, and sewer pipelines. The paper focuses on operational modal analysis (OMA) application for condition monitoring of operating pipelines. Special focus is on the topicality of OMA for definition of the dynamic features of the pipeline (frequencies and mode shapes) in operation. The research was conducted using two operating laboratory models imitated a part of the operating pipeline. The results of finite-element modeling, identification of pipe natural modes and its modification under the influence of virtual failure are discussed. The work considers the results of experimental research of dynamic behavior of the operating pipe models using one of OMA techniques and comparing dynamic properties with the modeled data. The study results demonstrate sensitivity of modal shape parameters to modification of operating pipeline technical state. Two strategies of pipeline repair – with continuously condition-based monitoring with proposed technology and without such monitoring, was discussed. Markov chain reliability models for each strategy were analyzed and reliability improvement factor for proposed technology of monitoring in compare with traditional one was evaluated. It is resumed about ability of operating pipeline condition monitoring by measuring dynamic deformations of the operating pipe and OMA techniques application for dynamic properties extraction.
Dissertations / Theses on the topic "Operational mode shape"
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Capraro, Ilaria. "Operational Modal Analysis: the CEME Skywalk at UBC, Vancouver." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/4240/.
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Slender and lighter footbridges are becoming more and more popular to meet the transportation demand and the aesthetical requirements of the modern society. The widespread presence of such particular structures has become possible thanks to the availability of new, lightweight and still capable of carrying heavy loads material .
Therefore, these kind of structure, are particularly sensitive to vibration serviceability problems, especially induced by human activities. As a consequence, it has been imperative to study the dynamic behaviour of such slender pedestrian bridges in order to define their modal characteristics.
As an alternative to a Finite Element Analysis to find natural frequencies, damping and mode shape, a so-called Operational Modal Analysis is a valid tool to obtain these parameters through an ambient vibration test.
This work provides a useful insight into the Operational Modal Analysis technique and It reports the investigation of the CEME Skywalk, a pedestrian bridge located at the University of British Columbia, in Vancouver, Canada.
Furthermore, human-induced vibration tests have been performed and the dynamic characteristics derived with these tests have been compared with the ones from the ambient vibration tests. The effect of the dynamic properties of the two buildings supporting the CEME Skywalk on the dynamic behaviour of the bridge has been also investigated.
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Petersson, Viktor, and Andreas Svanberg. "Operational modal analysis and finite element modeling of a low-rise timber building." Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-105208.
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Timber is a building material that is becoming more common and of interest for use in high-rise buildings. One of the reasons is that timber requires less energy input for the manufacturing process of the material compared to non-wood based materials. When designing high- rise timber buildings it is of great significance to understand the dynamic behavior of the structure. One method to obtain the dynamic properties is to use Operational Modal Analysis, which is based on the structural response from operational use. Finite element (FE) analysis is a tool which can be used for dynamic analysis for large structures. In this study an Operation Modal Analysis (OMA) was conducted on a four-story timber building in Växjö. A finite element model was created of the same building using commercial FE packages. Based on the mode shapes and natural frequencies obtained from the OMA, the FE model was fine-tuned. The purpose of this thesis is to gain knowledge of which parameters that might have a significant role in finite element modelling for a structural dynamic analysis. The aim is to develop a finite element model that accurately simulates the dynamic behavior of the tested building. It was shown from the result that is possible with an enough detailed FE model to capture the dynamic behaviour of a structure. The parameters that had the largest effect on the result can be pointed to the mass and the stiffness of the structure.Trä är ett byggnadsmaterial som börjar bli allt mer vanligt och är av intresse att använda som stommaterial för höga byggnader. En anledning till detta är att det krävs mindre energi i tillverkningsfasen för trä jämfört med stål och betong. Vid dimensionering av höga träbyggnader är det essentiellt att förstå byggnadens dynamiska egenskaper. För att ta fram en byggnads dynamiska egenskaper kan en metod som benämns Operational Modal Analysis (OMA) tillämpas vilken baseras på byggnadens rörelser vid daglig användning. Finita element (FE) metoden är ett verktyg som kan användas vid dynamisk analys för större byggnader. I detta arbete genomfördes en OMA för ett fyravåningshus med trästomme beläget i Växjö. Genom användning av kommersiella FE-mjukvaror togs en finita element modell av samma byggnad fram. Baserat på de egenfrekvenser och egenmoder erhållna från OMA, uppdaterades FE-modellen därefter. Syftet med detta arbete är att erhålla kunskap kring vilka parametrar som har betydelse vid FE-modellering med hänsyn till dynamisk analys. Syftet är även att validera den prototyp av datainsamlingsenhet som använts vid fältmätningen. Målet med arbetet är att ta fram en FE-modell som på ett korrekt sätt beskriver den testade byggnadens dynamiska beteende. Resultatet av arbetet påvisar att med en tillräckligt detaljerad FE-modell är det möjligt att erhålla en byggnads dynamiska egenskaper. De parametrar som har störst inverkan på resultatet är byggnadens styvhet och inkluderad massa.
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Song, Baiyi. "Evaluate Operational Modal Analysis and Compare the Result to Visualized Mode Shapes." Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-15599.
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The prototypes vibration test carried out for obtaining reliable information concerning machine’s dynamic properties in development process. Analysis results should be able to correlate with FE model to determine if some underlying assumptions (material properties & boundary conditions) were correct. EMA used for extracting structure modal parameter under laboratory condition. However, EMA can generally not provide all required information concerning machine dynamic property. To simulate vibration in operating, it commonly requires the model based on dynamic properties of the machine under operating. Thus, vibration tests need carried out under operational condition. OMA is a useful tool for extracting information concerning dynamic properties of operating machine. This report concerns vibration test of part of mining machine under operating condition. Modal parameters extracted by two kinds of OMA methods. Results from OMA was compared with corresponding EMA results, illustrates reader the advantages of OMA.
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Solomon, Brad K. "Methods for Identifying Acoustic Emissions From the Front Face of a Small Piezoelectric Blower." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3542.
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This thesis focuses on identifying acoustic noise generating components in piezoelectric blowers through transverse velocity measurements and the development of a numerical fluid model. Piezoelectric ceramics have proven useful for many industries and areas of research involving: high precision actuators, noise control, ultrasonic devices, and many other areas. As of late, a unique adaptation of piezoelectric ceramics is surfacing in the area of pumping and cooling. Air pumps that use these ceramics replace the traditional electric motor, resulting in lower power consumption, less moving parts, constant pressure gradients, lower overall weight, and a low profile. The current drawback of this application is the acoustic radiation produced by the blowers. Since these blowers are new to market, little research or development has been done to characterize the noise emissions. This thesis studies the acoustic emissions from the front face of a Murata piezoelectric blower. Jet noise and structural vibrations are two acoustic sources of interest that are studied in this research. A Direct Numerical Simulation (DNS) of the fluid flow through a Murata blower is developed to better identify noise generating mechanisms. The model solutions predict trends in sound pressure levels (SPL) of the jet noise and volumetric flow rates. Both the SPL and flow rate are shown to be functions of critical geometrical dimensions within the flow path of a Murata blower. Important dimensional components are identified as well as non-influential ones. Design guidelines are given to reduce noise emission from the front side of a blower and increase the volumetric flow rate. The results of this research have a direct impact on the piezoelectric blower industry and future blower designs.
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Dama, Nilesh Madhavji. "Discrete Element Modeling of Railway Ballast for Studying Railroad Tamping Operation." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/94026.
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The behavior of the ballast particles during their interaction with tamping tines in tamping operation is studied by developing a simulation model using the Discrete Element Model (DEM), with the aim of optimizing the railroad tamping operation. A comprehensive literature review is presented showcasing the applicability of DEM techniques in modeling ballast behavior and its feasibility in studying the fundamental mechanisms that influence the outcome of railroad tamping process is analyzed. The analysis shows that DEM is an excellent tool to study tamping operation as its important and unprecedented insights into the process, help not only to optimize the current tamping practices but also in the development of novel methods for achieving sustainable improvements in the track stability after tamping. The simulation model is developed using a commercially available DEM software called PFC3D (Particle Flow Code 3D).
A detailed explanation is provided about how to set up the DEM model of railway ballast considering important parameters like selection and calibration of particle shapes, ballast mechanical properties, contact model, and parameters governing the contact force models. Tamping operation is incorporated into the simulation model using a half-track layout with a highly modular code that enables a high degree of adjustability to allow control of all process parameters for achieving optimized output. A parametric study is performed to find the best values of tine motion parameters to optimize the linear tamping efficiency and a performance comparison has been made between linear and elliptical tamping. It is found that squeeze and release velocity of the tines should be lesser for better compaction of the particles and linear tamping is better compared to elliptical tamping.Master of Science
Railway track stability is the resistance of the tracks to deformation and is affected by the rail traffic, ballast fouling (contamination of ballast) and the changing environmental conditions. The track stability depends on the normal and frictional support provided by the ballast to the sleepers. Non-uniform ballast consolidation below the railway sleeper results in erratic wheel-rail contact forces, low traffic speeds, poor ride quality, and derailments. Thus, tamping is a railway track maintenance method done periodically on the railway tracks to ensure track stability. Tamping process involves compacting the railroad ballast underneath the sleeper. The sleeper is lifted by a desired height and then vibrating tamping tools called tines are inserted into the ballast below the sleeper to fill the void created by lifting of the sleeper and the sleeper is dropped back on to the ballast. So, it is important to understand the ballast mechanics, dynamics and ballast’s behavioral response to the tamping operation. Since, large scale experiments such as this are difficult, this operation has been simulated in a commercially available software called PFC3D using a Discrete Element Model (DEM) to represent the railway ballast. It is shown through a simulation that though spherical particles provide better computational efficiency, they cannot capture the exact ballast behavior like clumps (a collection of spherical pebbles). So using clumps to represent ballast, efforts are made to optimize the linear tamping efficiency. This is done by changing the values of parameters like tine amplitude, tine frequency, insertion velocity and squeeze velocity and finding their optimum values. Linear tamping results are compared with elliptical tamping. Thus, an optimum tamping cycle would help save money spent on the track maintenance activities.
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Jain, Ashish. "Discrete Element Modeling of Railway Ballast for Studying Railroad Tamping Operation." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/91438.
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The development of Discrete Element Model (DEM) of railway ballast for the purpose of studying the behavior of ballast particles during tamping is addressed in a simulation study, with the goal of optimizing the railroad tamping operation. A comprehensive literature review of applicability of DEM techniques in modeling the behavior of railway ballast is presented and its feasibility in studying the fundamental mechanisms that influence the outcome of railroad tamping process is analyzed. A Discrete Element Model of railway ballast is also developed and implemented using a commercially available DEM package: PFC3D. Selection and calibration of ballast parameters, such as inter-particle contact force laws, ballast material properties, and selection of particle shape are represented in detail in the model. Finally, a complete tamping simulation model is constructed with high degree of adjustability to allow control of all process parameters for achieving realistic output.
The analysis shows that DEM is a highly valuable tool for studying railroad tamping operation. It has the capability to provide crucial and unprecedented insights into the process, facilitating not only the optimization of current tamping practices, but also the development of novel methods for achieving sustainable improvements in track stability after tamping in the future. Different ways of modeling particle shapes have been evaluated and it has been shown that while using spheres to represent irregular ballast particles in DEM provides immense gains in computational efficiency, spheres cannot intently capture all properties of irregularly shaped particles, and therefore should not be used to model railway ballast particles. Inter-particle and wall-particle contact forces are calculated using Hertzian contact mechanics for determining ballast dynamics during tamping. The results indicate that the model is able to accurately predict properties of granular assemblies of the railway ballast in different test cases. The developed model for simulating tamping operation on a half-track layout is expected to be extended in future studies for evaluating rail track settlement and stability, optimization of tamping process, and performance of different ballast gradations.MS
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Oliveira, Lucas Rangel de. "Concepção de um índice para localização de trincas em eixos rotativos através da análise do SDI (Shape and Directivity Index) /." Ilha Solteira, 2019. http://hdl.handle.net/11449/180841.
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Orientador: Gilberto Pechoto de MeloResumo: A identificação de trincas ainda é um desafio na área de monitoramento da integridade estrutural em eixos rotativos. Embora muitas técnicas e modelos tenham sido desenvolvidos, encontrar uma técnica eficiente que possa localizar uma única ou múltiplas trincas ao longo do eixo, ainda é um grande desafio. Nesse trabalho, um novo índice para localização de trincas em eixos rotativos é apresentado. A equação do movimento do rotor com trinca utiliza a notação em coordenadas complexas a fim de separar as contribuições dos modos de precessão direta e retrógrada. O índice SDI (shape and directivity index) é calculado para o rotor, cujo modelo matemático considera a variação instantânea da rigidez do elemento finito devido à abertura e o fechamento gradual da trinca, conhecido como efeito breathing. Através da manipulação do SDI no modelo de cores HSV (hue, saturation and value), desenvolve-se uma escala métrica, visualizada em um mapa de cores, que possibilita localizar a anisotropia causada pela trinca ao longo do eixo. Profundidade e posição da trinca, presença de múltiplas trincas, entre outros fatores que afetam a assinatura da trinca em outros métodos de identificação são analisados. Bons resultados demonstram a eficiência e robustez do novo índice para diversos casos de operação do rotor. Essa métrica de dano acrescenta uma contribuição para os métodos de localização de trincas em sistemas rotativos.
Abstract: Crack identification is still a challenge in the area of structural health monitoring dedicated to rotating shafts. Although many techniques and models have been developed, finding an efficient technique capable of locating a single or multiple cracks along the shaft is still a challenge. In this work, a new index for locating cracks in rotating shafts is proposed. The equation of motion of the cracked rotor uses notation in complex coordinates in order to separate the contributions of forward and backward precession modes. The SDI (shape and directivity index) is calculated for the cracked rotor, which mathematical model considers the instantaneous variation of the finite element stiffness due to the gradual opening and closing of the crack, known as the breathing effect. By manipulating the SDI in the HSV (hue, saturation and value) color model, a metric scale is developed to locate the anisotropy caused by cracks along the shaft, visualized on a color map. Depth and position of the crack, presence of multiple cracks, among other factors that affect the signature of the crack in other identification methods are analyzed. Good results demonstrate the efficiency and robustness of the new index for several rotor operation conditions. This damage metric contributes to crack localization methods in rotating systems.
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Pop, Miroslav. "Ověřování věrohodnosti měřicí metody z oblasti modální analýzy." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-401587.
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This diploma thesis deals with the issue of operational modal analysis, which is one of the newer areas of structural dynamics that makes it possible to estimate modal properties of structures directly during their operation. The aim of this work is to create theoretical basis of operational modal analysis, more specifically of Frequeny Domain Decomposition method. Furthermore, apply this method to a selected structure and verify the achieved results using computational modelling and experimental modal analysis. The technique of dividing the experiment to separate measurements using reference sensor was used. Evaluation of the operational modal analysis was performed using self-created function for the MATLAB software and using the commercial PULSE Operational Modal Analysis software. Obtained results were verified by computational modelling and experimental modal analysis.
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Aboelfotoh, Aaya H. F. "Optimizing the Multi-Objective Order Batching Problem for Warehouses with Cluster Picking." Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1564663802880513.
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Ferreira, Vasco Guedes. "The analysis of primary metered half-hourly electricity and gas consumption in municipal buildings." Thesis, De Montfort University, 2009. http://hdl.handle.net/2086/3268.
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This thesis addressed the need for improved analysis and interpretation of primary meter half-hourly energy consumption data. The current work offers a novel benchmarking technique that was tested for 6 types of municipal buildings. This approach is different from conventional annual benchmarking mainly because it uses electricity and gas data in half-hourly periods, together with outside temperature data. A survey to European local authorities’ metering and monitoring practices was conducted in order to assess municipal energy managers' current procedures and needs in terms of data analysis to assess building energy performance and to identify potential energy saving opportunities. The benchmarking approach was developed considering the energy managers’ needs, but also the state-of the art in terms of building energy monitoring techniques, particularly building energy signatures, and the analysis techniques used on electricity grid demand forecasting. The benchmarking approach is based on the use of a metric composed of several indicators that are related to the load demand shape profile and the building energy signature. The comparison of indicators for buildings of the same type using standard scores identifies uncommon load demand profile characteristics and/or gas dependency on outside temperature in specific buildings. The metric is able to support the identification of potential energy wastage, which is linked to the detection of opportunities to save energy. The benchmarking technique was tested in 81 municipal building owned by Leicester City Council. This methodology can be applied to any non-domestic building equipped with primary meters for registering half-hourly electricity and gas consumption. In theory, this approach can also be applied to residential buildings, and to other short time series data types, for example quarter-hourly or 10 minutes interval data. The main contribution of this thesis is to improve the objectivity of building primary meter half-hourly electricity and gas consumption data analysis and interpretation by using quantitative parameters, instead of subjective visualisation techniques. The interpretation of building consumption data in short time series periods can now be streamlined, automated and perhaps incorporated in existing energy analysis software. This thesis raises questions that can lead to future research projects aiming to improve the metric and also to enlarge the scope of its application to national and European scale, to other building types and to other utilities.
Books on the topic "Operational mode shape"
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Gershun, Martha, and John D. ,. MD Lantos. Kidney to Share. Cornell University Press, 2021. http://dx.doi.org/10.7591/cornell/9781501755439.001.0001.
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This book tells the story of the author's decision to donate a kidney to a stranger. The book takes readers through the complex process by which such donors are vetted to ensure that they are physically and psychologically fit to take the risk of a major operation. The story is also placed in the larger context of the history of kidney transplantation and the ethical controversies that surround living donors. The book helps readers understand the discoveries that made transplantation relatively safe and effective as well as the legal, ethical, and economic policies that make it feasible. The book explores the steps involved in recovering and allocating organs. It analyzes the differences that arise depending on whether the organ comes from a living donor or one who has died. It observes the expertise — and the shortcomings — of doctors, nurses, and other professionals and describes the burdens that we place on people who are willing to donate. It asks us to consider just how far society should go in using one person's healthy body parts in order to save another person. The book provides an account of organ donation that is both personal and analytical. A combination of perspectives leads to a profound and compelling exploration of a largely opaque practice. The book pulls back the curtain to offer readers a more transparent view of the fascinating world of organ donation.
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Westendorf, Jasmine-Kim. Violating Peace. Cornell University Press, 2020. http://dx.doi.org/10.7591/cornell/9781501748059.001.0001.
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This book investigates sexual misconduct by military peacekeepers and abuses perpetrated by civilian peacekeepers and non-UN civilian interveners. Based on extensive field research in Bosnia, Timor-Leste, and with the UN and humanitarian communities, the book uncovers a brutal truth about peacebuilding as it investigates how such behaviors affect the capacity of the international community to achieve its goals related to stability and peacebuilding, and its legitimacy in the eyes of local and global populations. As the book shows, when interveners perpetrate sexual exploitation and abuse, they undermine the operational capacity of the international community to effectively build peace after civil wars and to alleviate human suffering in crises. Furthermore, sexual misconduct by interveners poses a significant risk to the perceived legitimacy of the multilateral peacekeeping project, and the United Nations more generally, with ramifications for the nature and dynamics of United Nations in future peace operations. The book illustrates how sexual exploitation and abuse relates to other challenges facing UN peacekeeping, and shows how such misconduct is deeply linked to the broader cultures and structures within which peacekeepers work, and which shape their perceptions of and interactions with local communities. Effectively preventing such behaviors is crucial to global peace, order, and justice. The book thus identifies how policies might be improved in the future, based on an account of why they have failed to date.
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Geddes, Andrew. Governing Migration Beyond the State. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198842750.001.0001.
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International migration has become a salient concern in global politics, but there is also significant variation in governance responses. By focusing on four key world regions—Europe, North America, South America, and Southeast Asia—this book explores the underlying factors that shape governance responses. Rather than focusing on the more visible outputs or outcomes of governance processes such as laws and policies, this book opens the ‘black box’ of migration governance to reveal how understandings and representations of the causes and effects of migration held by key governance actors in these four regions have powerful effects not only on governance outcomes but more broadly on the prospects for global migration governance. By doing so, the book shows how migration governance systems, through their operation and effects, can shape migration—in its various forms—and the lived experiences of migrants.
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Feest, Uljana, and Friedrich Steinle. Experiment. Edited by Paul Humphreys. Oxford University Press, 2016. http://dx.doi.org/10.1093/oxfordhb/9780199368815.013.16.
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The authors provide an overview of philosophical discussions about the roles of experiment in science. First, they cover two approaches that took shape under the heading of “new experimentalism” in the 1980s and 1990s. One approach was primarily concerned with questions about entity realism, robustness, and epistemological strategies. The other has focused on exploratory experiments and the dynamic processes of experimental research as such, highlighting its iterative nature and drawing out the ways in which such research is grounded in experimental systems, concepts and operational definitions. Second, the authors look at more recent philosophical work on the epistemology of causal inference, in particular highlighting discussions in the philosophy of the behavioral and social sciences, concerning the extrapolation from laboratory contexts to the world.
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Nicholson, Nigel, and Nathan Selden. The Rhetoric of Medicine. Oxford University Press, 2019. http://dx.doi.org/10.1093/med/9780190457488.001.0001.
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The Rhetoric of Medicine explores problems that confront medical professionals today by first examining similar problems that confronted physicians in ancient Greece. This framework provides illuminating entry points into issues in the practice of medicine, enabling readers to understand more clearly their shape and operation in the modern context—as well as their possible solutions. Topics covered include larger cultural ideas about the body, the problems posed to physicians by working for money, how to compete with alternative healthcare providers, the restrictions on political involvement that come with identifying as a physician, how to maintain the autonomy and judgment central to the concept of professionalism, mentoring that is effective but not exclusive, and how physicians can recognize themselves as both professionals and patients. Ultimately, the book asks us to interrogate the narratives and ideas that shape medical care today and to revise and replace those that do not serve patient health.
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Karlberg, Helena. Craniosynostosis Repair. Edited by Erin S. Williams, Olutoyin A. Olutoye, Catherine P. Seipel, and Titilopemi A. O. Aina. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780190678333.003.0023.
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Craniosynostosis is the fusion of one or more cranial sutures; such fusion occurs due to multiple factors and typically occurs in utero. Depending on the sutures involved, the infant can have significant abnormalities in skull shape. The structural abnormality is corrected surgically, frequently after a series of operations starting from infancy and occurring even late in childhood, depending on the sutures that are fused. During these surgeries, an infant can lose substantial volumes of blood, increasing the risk of hypovolemia and venous air embolism. It is imperative for the pediatric anesthesiologist to employ various modalities to minimize blood loss and also recognize clinical signs indicating the need for transfusion.
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Metcalf, Michael, John Reid, and Malcolm Cohen. Fortran 2018 enhancements to interoperability with C. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198811893.003.0021.
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Some Fortran features were not available when interoperating with C; in particular, • optional dummy arguments, • assumed-length character dummy arguments, • assumed-shape arrays, • allocatable dummy arguments, and •pointer dummy arguments. Also, the frequent need to pass C pointers for low-level operations can lead to ugly code that is difficult to understand. Fortran 2018 addresses all of these issues. For optional arguments there are already widespread C programming idioms that can be followed, and so this is the simplest deficiency to correct. For all the other advanced Fortran features, the necessary information that needs to be passed to/from the C functions is passed with a C descriptor, and there are mechanisms provided for the C functions to use such descriptors. For more convenient low-level C interoperability, assumed-type dummy arguments are available. Additionally, the new assumed-rank feature can also be used in interoperable procedures.
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Salzman, Harold, and Stephen R. Rosenthal. Software by Design. Oxford University Press, 1994. http://dx.doi.org/10.1093/oso/9780195083408.001.0001.
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As computers become more and more integral to business and other organizational operations around the world, software design must increasingly meet the social demands of the workplace. This book provides an informative, cogent examination of how various social factors--such as organizational structure, workplace relations, and market conditions--together shape software developers' technical design decisions. Through a survey of major software companies and in-depth case studies of the banking, hospital, and equipment field service industries, the authors identify factors that influence specific design strategies and examine the significant consequences that engineering decisions have on users' work, workplace quality of life, and opportunities for autonomy and skill development. The book concludes with a chapter devoted to exploring how a progressive design approach can improve both the performance and working conditions of an organization. By providing an important empirical study of the social construction of technology, the authors offer an insightful understanding of the challenges inherent in effective software design. The book will appeal to professionals and students in software design, information systems management, computer science, and the sociology of work and technology.
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Hamera, Judith. Unfinished Business. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780199348589.001.0001.
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Unfinished Business argues that Michael Jackson and Detroit, both as material entities with specific histories and as representations with uncanny persistence, have something valuable to teach us about three decades of structural economic transition in the United States, and particularly about the changing nature of work and capitalism between the mid-1980s and 2016. They teach us about the racialization and aesthetics of these changes, how they operate as structures of feeling and representations as well as shifts in the dominant mode of production, and about how industrialization’s successor mode, financialization, uses imagery both very similar to and very different from that of its predecessor. The book uses the methods of performance studies to advance three major points. First, figural economies of tropes, dance and theater conventions, and actual performances shape and reflect the ways structural economic change in the United States between the mid-1980s and 2016 congeals into public spectacles, circulates through a wide variety of media, and offers “lessons” to be learned about normative and aberrant relations to capital in transitional times. Second, Michael Jackson and Detroit illuminate the operations of these figural economies with special clarity. Third, Jackson’s and Detroit’s figural potential resides in their capacities to both complicate and bring fictive coherence to the intertwining of race, work, and capital in this period. Sites examined include Jackson’s performances, media coverage of his life, plays featuring Detroit, plans for the city’s postindustrial revitalization, and Detroit installations the Heidelberg Project and Mobile Homestead.
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Stone, Geoffrey, and Lee Bollinger, eds. National Security, Leaks and Freedom of the Press. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780197519387.001.0001.
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The United States Supreme Court made a landmark decision in the Pentagon Papers case in 1971, concerning how government should balance its legitimate need to conduct its operations—especially those related to national security—in secret, with the public’s right and responsibility to know what its government is doing. The Pentagon Papers decision, though, left many important questions still unresolved and the circumstances that undergirded the system initiated by the decision have changed fundamentally in recent decades. Difficult problems call for a range of different perspectives. In this book, Lee C. Bollinger and Geoffrey R. Stone gather an array of remarkable, wise, and accomplished individuals to share their deep and broad expertise in the national security world, journalism, and academia. Each essay delves into important dimensions of the current system to explain how we should think about them, and to offer as many solutions as possible. A rigorous and serious analysis, this volume examines the incredibly complex and important issues that our nation must continue to address and strive to resolve as we move into the future.
Book chapters on the topic "Operational mode shape"
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Bernal, D. "Receptance Based Normalization of Operational Mode Shapes." In Linking Models and Experiments, Volume 2, 393–98. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-9305-2_29.
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Khatibi, M. M., M. R. Ashory, and A. Malekjafarian. "Mass-Stiffness Change Method for Scaling of Operational Mode Shapes: Experimental Results." In Structural Dynamics, Volume 3, 1569–77. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-9834-7_141.
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Castellini, P., P. Chiariotti, E. P. Tomasini, M. Martarelli, D. Di Maio, B. Weekes, and D. J. Ewins. "Recovery of Operational Deflection Shapes from Noise-Corrupted Measurement Data from CSLDV: Comparison Between Polynomial and Mode Filtering Approaches." In Topics in Modal Analysis II, Volume 8, 83–91. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-04774-4_8.
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Jonker, Jan, and Niels Faber. "Value(s) Creation." In Organizing for Sustainability, 151–66. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-78157-6_12.
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AbstractThis is the most challenging building block of the Business Model Template (BMT), defining how you shape and use transactions in your business model. Our society can be looked at as an endless flow of transactions translated into daily activities. They are based on either money, or on time or energy (for example); the latter we call hybrid transactions. They are the operational acts that demonstrate an appreciation of the value created between parties. In this chapter, we present a typology of transactions and related strategies, which in turn we link to the concept of multiple (hybrid) values (e.g. sales, take-back, deposit, rent and use). What we want to explain as clearly and as unambiguously as possible is how multiple value(s) creation can be achieved within and through a broad variety of transactions. If this chapter shows anything, it is how difficult it is to make multiple value creation concrete.
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Dinther, Clemens van, Christoph M. Flath, Johannes Gaerttner, Julian Huber, Esther Mengelkamp, Alexander Schuller, Philipp Staudt, and Anke Weidlich. "Engineering Energy Markets: The Past, the Present, and the Future." In Market Engineering, 113–34. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-66661-3_7.
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AbstractSince the beginning of the energy sector liberalization, the design of energy markets has become a prominent field of research. Markets nowadays facilitate efficient resource allocation in many fields of energy system operation, such as plant dispatch, control reserve provisioning, delimitation of related carbon emissions, grid congestion management, and, more recently, smart grid concepts and local energy trading. Therefore, good market designs play an important role in enabling the energy transition toward a more sustainable energy supply for all. In this chapter, we retrace how market engineering shaped the development of energy markets and how the research focus shifted from national wholesale markets to more decentralized and location-sensitive concepts.
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Yang, Tianpu, Junshi Gao, Xiaoming Chen, Yanchun Guo, and Shuo Sun. "Research on the Development Route of International Communication Accesses." In Communications in Computer and Information Science, 16–25. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-33-4922-3_2.
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AbstractWith the implementation of China’s Belt and Road Initiative, a new wave of globalization is taking shape, promoting the growth of international service requirements, which requires pre-deployment of international infrastructure. The construction of international communications infrastructure is an important guarantee for China’s major international activities, external communication activities, and the normal operation of global and regional economies. International Communication Accesses is an important part of international infrastructure. The development and construction of international accesses is not an intrinsic mode, which involves many factors. It needs long-term planning and local adaptation; it relies on both the policy environment and basic network resources; it should consider both return on investment and convenience services. This document puts forward the future construction route of international communication accesses based on the analysis of factors including macro policies, geographical environments, service requirements, circuit quality improvement, transmission resources, fund support, and security assurance.
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Bracho, Gerardo. "Failing to Share the Burden: Traditional Donors, Southern Providers, and the Twilight of the GPEDC and the Post-War Aid System." In The Palgrave Handbook of Development Cooperation for Achieving the 2030 Agenda, 367–91. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-57938-8_17.
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AbstractIn 2011 the International Community came together in Busan to create the Global Partnership for Effective Development Co-operation (GPEDC) as a common space to promote aid effectiveness. By 2014, however, the main providers of South-South cooperation (China, India, and Brazil) had left the GPEDC. This chapter seeks to understand why. Using an abstract model inspired by game theory to analyse the situation, it concludes that the main cause was that traditional donors and new Southern providers failed to agree on a consensual burden-sharing formula. The episode, meaningful in itself, illustrates the difficulties that the International Community faces to make room for the new emerging Southern powers in the post-war liberal order.
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Reimers, Fernando M. "Conclusions. Seven Lessons to Build an Education Renaissance After the Pandemic." In Implementing Deeper Learning and 21st Education Reforms, 171–98. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-57039-2_8.
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Abstract This chapter draws out seven lessons from the cross-country analysis of the six reforms studied in this chapter. These are: Lesson 1. The power of complex mindsets about education reform. The six reforms all reflect reliance on the worldviews presented in the five frames of reform: cultural, psychological, professional, institutional and political. Those that have been sustained relied on insights from more of these five frames than those that were short lived. Lesson 2. Implementation matters considerably. The chapter discusses how the implementation process in effect recreates a reform, and how the development of an operational strategy defining the details of reform is what in the end most matters to the success of reform. The chapter discusses how the six reforms produced rather distinct operational strategies of seemingly similar components of the reform such as the learning goals for students or teacher professional development. Implementation strategies are also based on implicit theories of how organizations work, and the chapter explains the usefulness of a developmental theory of how organizations evolve to designing strategies that are aligned with the functionings that are possible in a given developmental stage, while also helping the organization evolve towards higher levels of functioning. Lesson 3. The need for operational clarity. People can’t execute what they don’t understand, and a reform must be able to translate goals into clear objectives and reform components into clear tasks which can be widely communicated and understood, as well as tracked to discern improvement and course correct when necessary. Lesson 4. Large scale reform is a journey: Coherence, Completeness and the Five Frames. The chapter explains how using the five dimensional theory of educational change can support coherence and completeness in a reform. Lesson 5. Sequencing, pacing and the importance of first steps. An operational strategy needs to be sequenced attending to ambition of goals, to existing levels of capacity and to institutional stage of development of the system. The first steps in the sequence are consequential because they shape the narrative of reform in ways that have long lasting consequences. Lesson 6. Staying the course. Long policy cycles are essential for reforms to be implemented and to produce results, and those cannot be taken for granted. Coherence, communication and participation can garner support that sustains a reform over time. Lesson 7. Learning from experience to build system level capacity. Most important to the coherent implementation of a reform is to create opportunities for key stakeholders, at various levels of the system, to learn together as a result of implementing components of the reform. Creating feedback loops and processes for making sense of such information is critical to support such learning.
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Chang, C. M., and J. Y. Chou. "Integration of operational modal analysis with video cameras for mode shape extraction." In Life-Cycle Civil Engineering: Innovation, Theory and Practice, 700–703. CRC Press, 2021. http://dx.doi.org/10.1201/9780429343292-91.
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Gerschewski, Johannes. "Governing Markets in Autocratic Regimes." In The Governor's Dilemma, 239–56. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198855057.003.0012.
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This chapter applies competence–control theory to the analysis of autocratic regimes, a regime type that is particularly prone to opaqueness and hidden agendas in its use of intermediaries. Governance in autocracies goes beyond a hierarchical delegation mode to encompass complex cooptation arrangements as well. This chapter uses the two pathway cases of China after 1976 and North Korea after 1994 to highlight the differences between delegation and cooptation for the political economy of socialist autocracies. Both cases share similar starting conditions. The state founders, Mao Zedong and Kim Il Sung respectively, had died, leaving behind a power vacuum and a defunct central planning economy that lacked sufficient expertise and operational capacities for reform. In this crisis moment, China embarked on a cooptation pathway that reformed the economy successfully, while North Korea maintained its delegation mode, which not only led to policy failure but also spilled over to help shape the political architecture of the country.
Conference papers on the topic "Operational mode shape"
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Calvo, Lara Erviti, Gorka Agirre Castellanos, and Germán Gimenez. "Analysis of Instabilities in Railway Vehicles Employing Operational Modal Analysis." In 2015 Joint Rail Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/jrc2015-5697.
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The application of Operational Modal Analysis (OMA) in the railway sector opens a broad field of opportunities. The validation of the numerical model employed in the design phase is usually performed employing data obtained in static tests. The drawback is that some suspension parameters, such as dampers, only have an influence in the dynamic behavior and not in the static behavior. Because of that, the use of the mode shapes identified from track measurements in combination with the static tests leads to a more accurate validation of the numerical model. Apart from that, most passenger comfort and dynamic problems are associated to slightly damped modes. A correct identification of the modal parameters can be used as a continuous design improvement tool to improve the comfort and dynamic characteristics of future designs. Another valuable application of OMA techniques is the identification of the mode shapes corresponding to instabilities, due to the safety impact that they have. In railway vehicles, instabilities are associated to mode shapes that present a damping rate which decreases with the increase of the running speed. Above a certain speed value, the excitation coming from track cannot be damped by the vehicle and it reaches an unstable condition. This unstable condition leads to high acceleration levels experienced by the passengers and high interaction forces between the wheel and the rail that may lead to safety hazards. The speed above which the vehicle is unstable is known as critical speed, and has to be greater than the maximum speed of the vehicle with a reasonable safety margin. The use of OMA techniques allows identifying the mode shape that causes the instability. This paper presents the application of OMA techniques to measurements performed on a passenger vehicle, in which the speed was increased until the vehicle was unstable. The mode shape that caused the instability was identified as well as its corresponding natural frequency and damping rate.
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Saito, Keisuke, Shigeyuki Naruta, Hiroaki Eto, Osamu Saijo, and Kiyotaka Ohki. "Operational Modal Analysis of Existing Floating Structure." In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79829.
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The oceanic architectural buildings were designed in consideration of structural safety based on various structural calculations. However, there is not conclusive proof such as constructed buildings satisfy strength according to the expectation or the buildings built in 1970’s still satisfies specified concrete strength. Therefore, in this study, vibration characteristics of existing floating structure were measured by mode analysis. Generally mode analysis is performed by giving a measurement object a shock with the impulse hammer. But it is hard to be allowed to strike the existing oceanic architectural buildings with a big impulse hammer for a vibration experiment. Therefore, operational modal analysis (OMA) which does not give a shock to measurement object was adopted in this study. In the OMA, natural frequency, mode shape and damping ratio are calculated from the measurement results of ordinary vibration by ground vibration, winds and waves. OMA is used in a field of mechanical engineering. However, it is not easy to apply a vibration experiment by OMA to floating structure. It is because the mode peaks of rigid motions such as heaving and pitching motion in low frequency domain is prominent, and the mode peaks of elastic vibration are difficult to be confirmed. Firstly, we carried out a water tank experiment with floating elastic plate model. Concretely, elastic plate model in floating condition on the water was analyzed by OMA. Because mode peak of the elastic vibration in floating condition was detected by examining frequency response function carefully, it was confirmed that we could apply OMA to the vibration experiment of existing floating structure. Secondly, vibration characteristic of the floating lounge named “WATERLINE” in Tokyo Bay was investigated by OMA. Ordinary vibrations of the base and the building of “WATERLINE” were measured, and natural frequency, mode shape and damping ratio were calculated. And it was reported about vibration characteristic that is given by measurement of existing floating structure by OMA.
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Quintanar-Guzmán, Serket, Somasundar Kannan, Miguel A. Olivares-Mendez, and Holger Voos. "Operational Space Control of a Lightweight Robotic Arm Actuated by Shape Memory Alloy (SMA) Wires." In ASME 2016 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/smasis2016-9137.
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This paper presents the design and control of a two link lightweight robotic arm using a couple of antagonistic Shape Memory Alloy (SMA) wires as actuators. A nonlinear robust control law for accurate positioning of the end effector of the two-link SMA based robotic arm is developed to handle the hysteresis behavior present in the system. The model presented consists of two subsystems: firstly the SMA wires model and secondly the dynamics of the robotic arm itself. The control objective is to position the robotic arm’s end effector in a given operational plane position. For this regulation problem a sliding mode control law is applied to the hysteretic system. Finally a Lyapunov analysis is applied to the closed-loop system demonstrating the stability of the system under given conditions. The simulation results demonstrate the accurate and fast response of the control law for position regulation. In addition, the stability of the closed-loop system can be corroborated.
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Carden, Eoin Peter, and Mattias Lindblad. "Operational Modal Analysis of Torsional Modes in Rotating Machinery." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-26305.
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Traditional experimental modal testing techniques rely on controlled and measured excitation together with measured responses in order to identify the mode shape, natural frequency and damping factor of each mode. Applying a controlled and measured excitation to a rotor train when in operation is logistically difficult and especially challenging in the field. Operational modal analysis (OMA) identifies the modal parameters of a system from measurement of response due to some (unknown) excitation. OMA has proven successful over the past several decades on non-rotating structures but has relatively rarely been applied to rotating machinery. Case studies are presented demonstrating the use of OMA in identifying torsional modes on an electric motor driven reciprocating compressor, on a diesel engine driven fire water pump and on a marine propulsion system. In contrast to lateral modes, torsional modes of rotor trains are typically not speed dependent. However phenomena exist whereby the torsional modes may be different at stand still, off-load and at different loads. The case studies provide examples of such phenomena and also of significant differences between predicted and measured behaviour which suggests that improvements in industrial practice would be beneficial. Such improvements should be based on reconciliation of measured and predicted behaviour and OMA offers a valuable tool to facilitate this. OMA provides a significant benefit in investigating and understanding torsional behaviour in operation.
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Casartelli, Ernesto, Luca Mangani, Armando Del Rio, and Angelika Schmid. "Capturing S-Shape of Pump-Turbines by CFD Simulations Using an Anisotropic Turbulence Model." In ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/ajkfluids2019-5663.
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Abstract Pump-turbines cope very well with modern electricity-market demand, having high operational flexibility and storage capabilities. Nevertheless, dynamic operation of these machines can lead to very challenging transient conditions, depending on the shape of the characteristic. Mechanical integrity can be correspondingly affected. Therefore assessment of the characteristic during the design phase, i.e. before model testing, is of crucial importance. In the past years different attempts to accurately compute the characteristic under steady (i.e. fix point) and transient conditions have been undertaken using RANS CFD. While the SST turbulence model has become the reference for machine design, it often fails for conditions close to or around instabilities. Its strength to accurately predict separation close to sound conditions (i.e. mild part- and over-load) is no more helpful. Under unstable conditions, which are characterized by continuous unsteady vortex formation, turbulence isotropy as assumed by linear two equation models is no more the right choice. Accordingly a turbulence model able to capture anisotropy, EARSM (Explicit Algebraic Reynolds Stress Model), has been implemented in an in-house code and used for the computation of the characteristic of various machines, stable and unstable, in order to assess the model performance. In this paper computations of three different machines in turbine mode are presented. Results using steady boundary conditions (BC) in the unstable region as well as transient BC like load-rejection and runaway are computed with EARSM, showing its superiority compared to linear two equation models.
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LENARCIC, MARKUS, and ARNO GEHRER. "ANALYSIS OF UNDERLYING MECHANISMS OF S-SHAPE INSTABILITIES IN REVERSIBLE PUMP-TURBINES AND DEVELOPMENT OF COUNTERMEASURES FOR ENHANCING OPERATIONAL STABILITY DURING TRANSIENT MANEUVERS IN TURBINE MODE." In 38th IAHR World Congress. The International Association for Hydro-Environment Engineering and Research (IAHR), 2019. http://dx.doi.org/10.3850/38wc092019-1455.
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Mohammadi, Zohreh, and Mohammad R. Movahhedy. "Study of Chatter Stability in Boring Process Using Operating Deflection Shape." In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-38632.
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Chatter is a limiting factor in machining systems with adverse effects for workpiece surface, tool and machine life and material removal rate. Proper modelling of this phenomenon requires that the dynamic characteristics of the machining system is known. It is common to obtain the dynamic of the system by modal tests in stationary condition. However, the vibration characteristics of a machine change between its operating and resting mode. The goal of this work is to study vibrations in boring using the vibrational characteristic in operational conditions using the operating deflection shape method. In this paper, vibration characteristics of the in the boring bar is obtained by both modal analysis and operating deflection shape methods and the results are compared. The results show that differences exist between the two conditions that can be small or large in different machining conditions.
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Fu, Gen, and Alexandrina Untaroiu. "Development of a Modal Selection Method for Full Strain Field Estimation." In ASME 2020 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/detc2020-22371.
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Abstract Full field response of a structure is critical for evaluating the performance of large slender structures. Since only several discrete measurements can be acquired during operation, the data expansion method is important for the estimation of the full field responses of the large complex structure. In previous studies, modal transformation methods were mainly applied in model reduction/expansion and global shape sensing. Compared to other expansion methods, the modal method is straightforward to implement and computational efficient, which makes it the most suitable approach for real-time expansion. However, only the first several modes were included in the modal transformation method in previous studies. Since the errors due to truncated mode components can occur under high frequency band excitations, it is necessary to include all of the modes that contribute significantly to the responses of the structure. Therefore, in this study, a modal selection method based on operational modal analysis (OMA) is proposed for selecting proper modes. The modal characteristics of the system were derived with the strain data at several discrete locations. The contribution of each mode was quantified. By sorting the modes based on their contribution, the most significant modes can be used in the expansion process. Two operational modal analysis methods, stochastic system identification (SSI) and frequency domain decomposition (FDD), were considered and compared. The proposed approach was implemented with a computational model. Considerable improvement has been observed when high bandwidth excitations were added. The proposed modal selection method can successfully rank the participated modes. It can improve the accuracy of the modal transformation approach as shown in the impact loading case. It can be used for data expansion even when high frequency band is excited. Finally, we believe the novel methods presented in this study could be used in the development of more reliable health monitoring systems for turbomachinery.
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Urthaler, Yetzirah, Ryan Watson, and Jonathan Davis. "Lateral Buckling of Deepwater Pipelines in Operation." In ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/omae2012-83949.
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Deepwater pipeline systems are regularly designed to operate under high pressure and high temperature (HPHT) conditions. These operating environments typically mean that the systems are susceptible to Euler buckling, more commonly referred to as lateral buckling. An effective design solution, promoted by the SAFEBUCK JIP [1],[2] and now regularly adopted within the industry, is to accommodate the thermal expansion with planned buckle sites, thereby controlling the loads within the system. Traditionally, operators have spent a great deal of resources in designing, manufacturing and installing pipeline systems. However, it is equally important to demonstrate that the system is fit for service and that operational loads do not exceed the extreme design cases. In some instances, there have been a number of instances where lateral buckling has caused full bore rupture in offshore pipelines. In order to verify the long-term integrity of a pipeline system, it is essential to confirm the location, mode shape and amplitude of both the planned and rogue (unplanned) lateral buckles. This can be accomplished via pipeline surveys. Recent pipeline survey work was conducted on a pipeline system in the Gulf of Mexico. The data exhibited some areas of unexpected performance, which highlights the fact that operating uncertainty exists and that lateral buckling is an unstable phenomenon. The design Finite Element (FE) models were calibrated using the measured buckle shapes, and the fatigue life was estimated using recorded operational pressure and temperature data. The survey work performed has proven invaluable when assessing the long-term integrity of the pipeline system. This paper presents a review of the methods used for surveying a pipeline system in the Gulf of Mexico, a summary of the results obtained from the subsequent analysis and pipeline FE model calibration, as well as ‘lessons learned’ for future projects with similar design challenges.
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Lees, A. W., and M. I. Friswell. "The Estimation of Rotor Unbalance." In ASME 1997 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/detc97/vib-4039.
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Abstract A method is presented to determine the state of unbalance of a rotating machine. The only requirement of the procedure is a good numerical model for the rotor and an approximate model for the bearing behaviour. No assumptions are made concerning the operational mode shape of the rotor and the influence of the supporting structure is included in a consistent manner. For simplicity the analysis is presented in a single plane orthogonal to the rotor axis, but no difficulty is foreseen in extending the method to two planes. Examples are given for a two bearing system with both constant and varying bearing coefficients.
Reports on the topic "Operational mode shape"
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Foltz, Stuart, and Daniel Hooks. Lock operation improvements. Engineer Research and Development Center (U.S.), April 2021. http://dx.doi.org/10.21079/11681/40402.
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The U.S. Army Corps of Engineers (USACE) owns or operates 236 locks at 191 sites (HQUSACE 2016). Although the locks at these sites generally perform reliably, more than half of these structures have surpassed their 50-year economic design life and as such, there are increasing concerns about their continued safe, reliable operation. This work was undertaken to review lock operating equipment, maintenance practices, records pertaining to accidents and equipment failures, and lighting systems; to identify alternative improvements to equipment and equipment maintenance practices; and to analyze and compare those alternatives to determine and recommend optimal solutions. This report documents some lessons learned, primarily to share information that others might find useful. Note that the recommendations in this report should not be viewed as policy, although some might be considered by those creating policy.
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Terzic, Vesna, and William Pasco. Novel Method for Probabilistic Evaluation of the Post-Earthquake Functionality of a Bridge. Mineta Transportation Institute, April 2021. http://dx.doi.org/10.31979/mti.2021.1916.
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While modern overpass bridges are safe against collapse, their functionality will likely be compromised in case of design-level or beyond design-level earthquake, which may generate excessive residual displacements of the bridge deck. Presently, there is no validated, quantitative approach for estimating the operational level of the bridge after an earthquake due to the difficulty of accurately simulating residual displacements. This research develops a novel method for probabilistic evaluation of the post-earthquake functionality state of the bridge; the approach is founded on an explicit evaluation of bridge residual displacements and associated traffic capacity by considering realistic traffic load scenarios. This research proposes a high-fidelity finite-element model for bridge columns, developed and calibrated using existing experimental data from the shake table tests of a full-scale bridge column. This finite-element model of the bridge column is further expanded to enable evaluation of the axial load-carrying capacity of damaged columns, which is critical for an accurate evaluation of the traffic capacity of the bridge. Existing experimental data from the crushing tests on the columns with earthquake-induced damage support this phase of the finite-element model development. To properly evaluate the bridge's post-earthquake functionality state, realistic traffic loadings representative of different bridge conditions (e.g., immediate access, emergency traffic only, closed) are applied in the proposed model following an earthquake simulation. The traffic loadings in the finite-element model consider the distribution of the vehicles on the bridge causing the largest forces in the bridge columns.
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Yan, Yujie, and Jerome F. Hajjar. Automated Damage Assessment and Structural Modeling of Bridges with Visual Sensing Technology. Northeastern University, May 2021. http://dx.doi.org/10.17760/d20410114.
Full textAbstract:
Recent advances in visual sensing technology have gained much attention in the field of bridge inspection and management. Coupled with advanced robotic systems, state-of-the-art visual sensors can be used to obtain accurate documentation of bridges without the need for any special equipment or traffic closure. The captured visual sensor data can be post-processed to gather meaningful information for the bridge structures and hence to support bridge inspection and management. However, state-of-the-practice data postprocessing approaches require substantial manual operations, which can be time-consuming and expensive. The main objective of this study is to develop methods and algorithms to automate the post-processing of the visual sensor data towards the extraction of three main categories of information: 1) object information such as object identity, shapes, and spatial relationships - a novel heuristic-based method is proposed to automate the detection and recognition of main structural elements of steel girder bridges in both terrestrial and unmanned aerial vehicle (UAV)-based laser scanning data. Domain knowledge on the geometric and topological constraints of the structural elements is modeled and utilized as heuristics to guide the search as well as to reject erroneous detection results. 2) structural damage information, such as damage locations and quantities - to support the assessment of damage associated with small deformations, an advanced crack assessment method is proposed to enable automated detection and quantification of concrete cracks in critical structural elements based on UAV-based visual sensor data. In terms of damage associated with large deformations, based on the surface normal-based method proposed in Guldur et al. (2014), a new algorithm is developed to enhance the robustness of damage assessment for structural elements with curved surfaces. 3) three-dimensional volumetric models - the object information extracted from the laser scanning data is exploited to create a complete geometric representation for each structural element. In addition, mesh generation algorithms are developed to automatically convert the geometric representations into conformal all-hexahedron finite element meshes, which can be finally assembled to create a finite element model of the entire bridge. To validate the effectiveness of the developed methods and algorithms, several field data collections have been conducted to collect both the visual sensor data and the physical measurements from experimental specimens and in-service bridges. The data were collected using both terrestrial laser scanners combined with images, and laser scanners and cameras mounted to unmanned aerial vehicles.
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Financial Stability Report - September 2015. Banco de la República, August 2021. http://dx.doi.org/10.32468/rept-estab-fin.sem2.eng-2015.
Full textAbstract:
From this edition, the Financial Stability Report will have fewer pages with some changes in its structure. The purpose of this change is to present the most relevant facts of the financial system and their implications on the financial stability. This allows displaying the analysis more concisely and clearly, as it will focus on describing the evolution of the variables that have the greatest impact on the performance of the financial system, for estimating then the effect of a possible materialization of these risks on the financial health of the institutions. The changing dynamics of the risks faced by the financial system implies that the content of the Report adopts this new structure; therefore, some analyses and series that were regularly included will not necessarily be in each issue. However, the statistical annex that accompanies the publication of the Report will continue to present the series that were traditionally included, regardless of whether or not they are part of the content of the Report. In this way we expect to contribute in a more comprehensive way to the study and analysis of the stability of the Colombian financial system. Executive Summary During the first half of 2015, the main advanced economies showed a slow recovery on their growth, while emerging economies continued with their slowdown trend. Domestic demand in the United States allowed for stabilization on its average growth for the first half of the year, while other developed economies such as the United Kingdom, the euro zone, and Japan showed a more gradual recovery. On the other hand, the Chinese economy exhibited the lowest growth rate in five years, which has resulted in lower global dynamism. This has led to a fall in prices of the main export goods of some Latin American economies, especially oil, whose price has also responded to a larger global supply. The decrease in the terms of trade of the Latin American economies has had an impact on national income, domestic demand, and growth. This scenario has been reflected in increases in sovereign risk spreads, devaluations of stock indices, and depreciation of the exchange rates of most countries in the region. For Colombia, the fall in oil prices has also led to a decline in the terms of trade, resulting in pressure on the dynamics of national income. Additionally, the lower demand for exports helped to widen the current account deficit. This affected the prospects and economic growth of the country during the first half of 2015. This economic context could have an impact on the payment capacity of debtors and on the valuation of investments, affecting the soundness of the financial system. However, the results of the analysis featured in this edition of the Report show that, facing an adverse scenario, the vulnerability of the financial system in terms of solvency and liquidity is low. The analysis of the current situation of credit institutions (CI) shows that growth of the gross loan portfolio remained relatively stable, as well as the loan portfolio quality indicators, except for microcredit, which showed a decrease in these indicators. Regarding liabilities, traditional sources of funding have lost market share versus non-traditional ones (bonds, money market operations and in the interbank market), but still represent more than 70%. Moreover, the solvency indicator remained relatively stable. As for non-banking financial institutions (NBFI), the slowdown observed during the first six months of 2015 in the real annual growth of the assets total, both in the proprietary and third party position, stands out. The analysis of the main debtors of the financial system shows that indebtedness of the private corporate sector has increased in the last year, mostly driven by an increase in the debt balance with domestic and foreign financial institutions. However, the increase in this latter source of funding has been influenced by the depreciation of the Colombian peso vis-à-vis the US dollar since mid-2014. The financial indicators reflected a favorable behavior with respect to the historical average, except for the profitability indicators; although they were below the average, they have shown improvement in the last year. By economic sector, it is noted that the firms focused on farming, mining and transportation activities recorded the highest levels of risk perception by credit institutions, and the largest increases in default levels with respect to those observed in December 2014. Meanwhile, households have shown an increase in the financial burden, mainly due to growth in the consumer loan portfolio, in which the modalities of credit card, payroll deductible loan, revolving and vehicle loan are those that have reported greater increases in risk indicators. On the side of investments that could be affected by the devaluation in the portfolio of credit institutions and non-banking financial institutions (NBFI), the largest share of public debt securities, variable-yield securities and domestic private debt securities is highlighted. The value of these portfolios fell between February and August 2015, driven by the devaluation in the market of these investments throughout the year. Furthermore, the analysis of the liquidity risk indicator (LRI) shows that all intermediaries showed adequate levels and exhibit a stable behavior. Likewise, the fragility analysis of the financial system associated with the increase in the use of non-traditional funding sources does not evidence a greater exposure to liquidity risk. Stress tests assess the impact of the possible joint materialization of credit and market risks, and reveal that neither the aggregate solvency indicator, nor the liquidity risk indicator (LRI) of the system would be below the established legal limits. The entities that result more individually affected have a low share in the total assets of the credit institutions; therefore, a risk to the financial system as a whole is not observed. José Darío Uribe Governor