scholarly journals Reliability of Field Experiments, Analytical Methods and Pedestrian’s Perception Scales for the Vibration Serviceability Assessment of an In-Service Glass Walkway

2019 ◽  
Vol 9 (9) ◽  
pp. 1936 ◽  
Author(s):  
Chiara Bedon ◽  
Marco Fasan
Keyword(s):  
Field Experiments ◽  
Dynamic Performance ◽  
Careful Consideration ◽  
Design Stage ◽  
Mechanical Degradation ◽  
Operational Conditions ◽  
Damage Scenarios ◽  
Technical Interest ◽  
High Flexibility ◽  
Pedestrian System

The vibration performance of pedestrian structures attracts the attention of several studies, especially with respect to unfavorable operational conditions or possible damage scenarios. Given a pedestrian system, specific vibration comfort levels must be satisfied in addition to basic safety requirements, depending on the class of use, the structural typology and the materials. To this aim, guideline documents of the literature offer simplified single-degree-of-freedom (SDOF) approaches to estimate the maximum expected vibrations and to verify the required comfort limits. Most of these documents, however, are specifically calibrated for specific scenarios/structural typologies. Dedicated methods of design and analysis, in this regard, may be required for structural glass pedestrian systems, due to their intrinsic features (small thickness-to-size ratios, high flexibility, type and number of supports, live-to-dead load ratios, use of materials that are susceptible to mechanical degradation with time/temperature/humidity, etc.). Careful consideration could be then needed not only at the design stage, but also during the service life of a given glass walkway. In this paper, the dynamic performance of an in-service glass walkway is taken into account and explored via field vibration experiments. A set of walking configurations of technical interest is considered, involving 20 volunteers and several movement features. The vibration comfort of the structure is then assessed based on experimental estimates and existing guideline documents. The intrinsic uncertainties and limits of simplified approaches of literature are discussed, with respect to the performance of the examined glass walkway. In conclusion, the test predictions are also used to derive “perception index” data and scales that could support a reliable vibration comfort assessment of in-service pedestrian glass structures.

scholarly journals Efficiency of Coupled Experimental–Numerical Predictive Analyses for Inter-Story Floors Under Non-Isolated Machine-Induced Vibrations

Actuators ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 87 ◽  
Author(s):  
Enrico Bergamo ◽  
Marco Fasan ◽  
Chiara Bedon
Keyword(s):  
Precast Concrete ◽  
Dynamic Performance ◽  
Computational Cost ◽  
Numerical Control ◽  
Design Stage ◽  
Vibration Source ◽  
Operational Conditions ◽  
Early Design Stage ◽  
Concrete Frame ◽  
Industrial Buildings

Machine-induced vibrations represent, for several reasons, a crucial design issue for industrial buildings. At the early design stage, special attention is thus required for the static and dynamic performance assessment of the load-bearing members, given that they should optimally withstand ordinary design loads but also potentially severe machinery operations. The knowledge and reliable description of the input vibration source is a key step, similarly to a reliable description of the structural system, to verify. However, such a kind of detailing is often unavailable and results in a series of simplified calculation assumptions. In this paper, a case-study eyewear factory built in 2019 is investigated. Its layout takes the form of a two-story, two-span (2 × 14.6 m) precast concrete frame (poor customer/designer communication on the final equipment resulted in various non-isolated computer numerical control (CNC) vertical machines mounted on the inter-story floor, that started to suffer from pronounced resonance issues. Following past experience, this paper investigates the validity of a coupled experimental–numerical method that could be used for efficient assessment predictive studies. Based on on-site experiments with Micro Electro-Mechanical Systems (MEMS) accelerometers mounted on the floor and on the machine (spindle included), the most unfavorable machine-induced vibration sources and operational conditions are first characterized. The experimental outcomes are thus used to derive a synthetized signal that is integrated in efficient one-bay finite element (FE) numerical model of the floor, in which the machine–structure interaction can be taken into account. The predictability of marked resonance issues is thus emphasized, with a focus on potential and possible limits of FE methods characterized by an increasing level of detailing and computational cost.

scholarly journals A Novel Methodology for Adaptive Coordination of Multiple Controllers in Electrical Grids

Mathematics ◽  
2021 ◽  
Vol 9 (13) ◽  
pp. 1474
Author(s):  
Ruben Tapia-Olvera ◽  
Francisco Beltran-Carbajal ◽  
Antonio Valderrabano-Gonzalez ◽  
Omar Aguilar-Mejia
Keyword(s):  
Power Systems ◽  
Power System ◽  
Electric Power ◽  
Large Scale ◽  
Short Circuit ◽  
Dynamic Performance ◽  
Low Frequency ◽  
Electric Power System ◽  
Design Stage ◽  
Positive Interaction

This proposal is aimed to overcome the problem that arises when diverse regulation devices and controlling strategies are involved in electric power systems regulation design. When new devices are included in electric power system after the topology and regulation goals were defined, a new design stage is generally needed to obtain the desired outputs. Moreover, if the initial design is based on a linearized model around an equilibrium point, the new conditions might degrade the whole performance of the system. Our proposal demonstrates that the power system performance can be guaranteed with one design stage when an adequate adaptive scheme is updating some critic controllers’ gains. For large-scale power systems, this feature is illustrated with the use of time domain simulations, showing the dynamic behavior of the significant variables. The transient response is enhanced in terms of maximum overshoot and settling time. This is demonstrated using the deviation between the behavior of some important variables with StatCom, but without or with PSS. A B-Spline neural networks algorithm is used to define the best controllers’ gains to efficiently attenuate low frequency oscillations when a short circuit event is presented. This strategy avoids the parameters and power system model dependency; only a dataset of typical variable measurements is required to achieve the expected behavior. The inclusion of PSS and StatCom with positive interaction, enhances the dynamic performance of the system while illustrating the ability of the strategy in adding different controllers in only one design stage.

scholarly journals Using a qualitative and quantitative validation methodology to evaluate a drone detection system

ACTA IMEKO ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 20
Author(s):  
Daniela Doroftei ◽  
Geert De Cubber
Keyword(s):  
Detection System ◽  
Weather Conditions ◽  
Careful Consideration ◽  
Technical Aspects ◽  
Operational Conditions ◽  
Qualitative And Quantitative ◽  
Detection Systems ◽  
Quantitative Score ◽  
Validation Procedure ◽  
Quantitative Validation

Now that the use of drones is becoming more common, the need to regulate the access to airspace for these systems is becoming more pressing. A necessary tool in order to do this is a means of detecting drones. Numerous parties have started the development of such drone detection systems. A big problem with these systems is that the evaluation of the performance of drone detection systems is a difficult operation that requires the careful consideration of all technical and non-technical aspects of the system under test. Indeed, weather conditions and small variations in the appearance of the targets can have a huge difference on the performance of the systems. In order to provide a fair evaluation, it is therefore paramount that a validation procedure that finds a compromise between the requirements of end users (who want tests to be performed in operational conditions) and platform developers (who want statistically relevant tests) is followed. Therefore, we propose in this article a qualitative and quantitative validation methodology for drone detection systems. The proposed validation methodology seeks to find this compromise between operationally relevant benchmarking (by providing qualitative benchmarking under varying environmental conditions) and statistically relevant evaluation (by providing quantitative score sheets under strictly described conditions).

Dynamics Analysis of Steel-Concrete Composite Box Beams

2014 ◽  
Vol 528 ◽  
pp. 94-100
Author(s):  
Li Zhong Jiang ◽  
Xin Kang ◽  
Chang Qing Li
Keyword(s):  
Dynamic Performance ◽  
Composite Beams ◽  
Design Stage ◽  
Finite Element Program ◽  
Long Span ◽  
Box Beam ◽  
Long Span Bridge ◽  
Element Program ◽  
Box Beams ◽  
Composite Box Beam

Steel-concrete composite box beams have been widely used in high rise buildings and long-span bridge structures. But so far, almost all researches have been aimed at the static behavior of the composite beams and dynamic behavior of steel and concrete composite beams have been rarely studied. In this paper, by using general finite element program ANSYS to analyze the dynamic performance of the composite box beam under different geometric parameters. Research is focused on the slip stiffness、width-to-thickness ratio、depth-span ratio and the height ratio of cross section to the vibration characteristics of composite box beam. The results indicate that these factors affect the seismic dynamic response of steel-concrete composite box beams most and they should be controlled according to different situations in seismic design stage.

scholarly journals Adjustments for Wind-Induced Undercatch in Snowfall Measurements Based on Precipitation Intensity

2020 ◽  
Vol 21 (5) ◽  
pp. 1039-1050 ◽  
Author(s):  
Matteo Colli ◽  
Mattia Stagnaro ◽  
Luca G. Lanza ◽  
Roy Rasmussen ◽  
Julie M. Thériault
Keyword(s):  
Wind Speed ◽  
Field Experiments ◽  
Transfer Functions ◽  
Collection Efficiency ◽  
Surface Air Temperature ◽  
Field Measurements ◽  
Precipitation Intensity ◽  
Operational Conditions ◽  
Explanatory Variables ◽  
Precipitation Gauge

AbstractAdjustments for the wind-induced undercatch of snowfall measurements use transfer functions to account for the expected reduction of the collection efficiency with increasing the wind speed for a particular catching-type gauge. Based on field experiments or numerical simulation, collection efficiency curves as a function of wind speed also involve further explanatory variables such as surface air temperature and/or precipitation type. However, while the wind speed or wind speed and temperature approach is generally effective at reducing the measurement bias, it does not significantly reduce the root-mean-square error (RMSE) of the residuals, implying that part of the variance is still unexplained. In this study, we show that using precipitation intensity as the explanatory variable significantly reduces the scatter of the residuals. This is achieved by optimized curve fitting of field measurements from the Marshall Field Site (Colorado, United States), using a nongradient optimization algorithm to ensure optimal binning of experimental data. The analysis of a recent quality-controlled dataset from the Solid Precipitation Intercomparison Experiment (SPICE) campaign of the World Meteorological Organization confirms the scatter reduction, showing that this approach is suitable to a variety of locations and catching-type gauges. Using computational fluid dynamics simulations, we demonstrate that the physical basis of the reduction in RMSE is the correlation of precipitation intensity with the particle size distribution. Overall, these findings could be relevant in operational conditions since the proposed adjustment of precipitation measurements only requires wind sensor and precipitation gauge data.

Frequency Domain Structural Optimization of a Flexible Manipulator Incorporating a PD Controller in the Design Stage

1999 ◽  
Author(s):  
Yong Hoon Chang ◽  
Ali Seireg
Keyword(s):  
Structural Optimization ◽  
Natural Frequency ◽  
Dynamic Performance ◽  
Integrated Design ◽  
Flexible Manipulator ◽  
Design Stage ◽  
Pd Controller ◽  
Design Strategies ◽  
Flexible Mode ◽  
Modal Mass

Abstract This study investigates the potential advantages of integrated design strategies for flexible manipulators that utilize a controller in the process of optimizing the structural design. Clamped free and clamped mass beam models are considered in the investigation for the structural optimization with respect to natural frequencies and mass. A PD controller is utilized in the design process with several objective functions that incorporate weighted combinations of the mass of the structure, modal mass, modal stiffness, and the natural frequency of the rigid mode and the dominant natural frequency of the flexible mode. The results show that the objective function, which minimizes the mass and the product of the modal mass and modal stiffness of the rigid mode and maximize the natural frequency of the flexible mode with appropriate weighting factors, gave the best dynamic performance. Although a two link tubular planar manipulator with a PD controller and assumed beam models for the links is considered in the optimization based on modal parameters, the reported approach can be extended to time domain optimization of multi-link spacial robots with complex structures designed to perform particular tasks.

Design for Additive Manufacture of Fine Medical Instrumentation—DragonFlex Case Study

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Filip Jelínek ◽  
Paul Breedveld
Keyword(s):  
Medical Device ◽  
Ceramic Composite ◽  
Design Stage ◽  
Additive Manufacture ◽  
Digital Light Processing ◽  
Advantages And Disadvantages ◽  
Material Choice ◽  
Superior Mechanical Properties ◽  
High Flexibility ◽  
Printing Processes

The recently popularized domain of additive manufacturing (AM) has much to offer to medical device development, especially to the growing field of minimally invasive surgery (MIS). With the advancements in AM materials, one could soon envision materializing not only the proofs of concept but also the final clinically approved instruments. DragonFlex—the world's first AM steerable MIS instrument prototype—was recently devised with the aim to follow this vision. Apart from the medical device design restrictions, several limitations of AM materials and processes had to be considered. The aim of this paper is to present these insights to those opting for this means of manufacture, serving as a helpful design and material guide. Over the course of its development, DragonFlex has gone through four design generations so far, each differing in the AM material and process used. Due to being a prototype of a MIS instrument of miniature dimensions, the printing processes were limited to stereolithography (SLA), as to achieve the best possible precision and accuracy. Each SLA process and material brought along specific advantages and disadvantages affecting the final printout quality, which needed to be compensated for either at the design stage, during, or after printing itself. The four DragonFlex generations were printed using the following SLA techniques and materials in this order: polymer jetting from Objet VeroBlue™; SLA Digital Light Processing™ (DLP) method from EnvisionTEC® NanoCure RCP30 and R5; conventional SLA from 3D Systems Accura® 60; and DLP based SLA process from a ceramic composite. The material choice and the printing orientation were found to influence the final printout accuracy and integrity of thin features, as well as material's postproduction behavior. The polymeric VeroBlue™ proved structurally sound, although suffering from undermined accuracy and requiring postprocessing, hence recommended for prototyping of upscaled designs of looser manufacturing tolerances or overdimensioned experimental setups. The NanoCure materials are capable of reaching the best accuracy requiring almost no postprocessing, thus ideal for prototyping small intricate features. Yet their mechanical functionality is undermined due to the high brittleness of RCP30 and high flexibility of R5. The transparent Accura® 60 was found to lose its strength and appeal due to high photosensitivity. Finally, the ceramic composite shows the best potential for medical use due to its biocompatibility and superior mechanical properties, yet one has to compensate for the material shrinkage already at the design stage.

Finite Element Analysis and Optimization of Structure for Large Blanking Machine Equipment during High-Speed Blanking

2011 ◽  
Vol 697-698 ◽  
pp. 176-181
Author(s):  
Shu Bo Xu ◽  
K.K. Sun ◽  
Cai Nian Jing ◽  
Guo Cheng Ren
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Optimal Design ◽  
High Speed ◽  
Dynamic Performance ◽  
Design Stage ◽  
Beam Structure ◽  
Element Analysis ◽  
Blanking Process ◽  
Dynamic Performance Analysis

This paper reviews the background and significance to investigate the high-speed speed blanking process modeling simulation and optimization of large blanking machine equipment for CNC uncoiling, leveling and shearing line. And a powerful tool has been providing to of heavy machinery optimal design specifications. The finite element model of beam structure has been established by using a three-dimensional modeling software UG NX4.0 CAD and finite element analysis software ANSYS. Then the static and dynamic characteristics results of the whole beam structure have been simulated. On the basis of analysis results, the optimal static and dynamic performance of square cross-section of the beam structure has been obtained. Drawings at the design stage of large blanking machine equipment for NC uncoiling, leveling and shearing line, the use of finite element theory and modal analysis theory, the structure of the blanking machine static and dynamic performance analysis and prediction using optimal design method for optimization, the new machine to improve job performance, improve processing accuracy, shorten the development cycle and enhance the competitiveness of products is very important.

An Experimental Study on Progressive and Dynamic Damage Stability Scenarios

2014 ◽  
Author(s):  
Oliver Lorkowski ◽  
Hendrik Dankowski ◽  
Florian Kluwe
Keyword(s):  
Experimental Study ◽  
Model Test ◽  
Static Model ◽  
Model Tests ◽  
Time Dependent ◽  
Test Series ◽  
Design Stage ◽  
Damage Scenarios ◽  
Damage Stability ◽  
Set Up

Current damage stability rules for ships are based on the evaluation of a ship’s residual stability in the final flooding stage. The consideration of the dynamic propagation of water within the inner subdivision as well as intermediate flooding stages and their influence on the resulting stability is very limited in the current damage stability regulations. The investigation of accidents like the one of the Estonia or the European Gateway reveals that intermediate stages of flooding and the dynamic flooding sequence result in significant fluid shifting moments which have a major influence on the time-dependent stability of damaged ships. Consequently, the critical intermediate stages should be considered when evaluating designs with large cargo decks like RoRo vessels, RoPax vessels and car carriers. Also the safety of large passenger ships with respect to damage stability is affected by the aforementioned effects. In this context a new numerical flooding simulation tool has been developed which allows an evaluation of a ship’s time-dependent damage stability including all intermediate stages of flooding. The simulation model is based on a quasi-static approach in the time domain with a hydraulic model for the fluxes to ease the computation and allow for fast and efficient evaluation within the early design stage of the vessel. This allows studying multiple damage scenarios within a short period. For the further validation of this numerical simulation method a series of model tests has been particularly set up to analyse the time-dependent damage stability of a floating body. The test-body has been designed specifically to reflect the most typical internal subdivision layouts of ships affected by the effects mentioned above. The experimental study covers a static model test series as well a dynamic one. The static model test series has been set up with the aim to analyse the progressive flooding of selected compartments in calm water. Within the dynamic model test series, the model is excited by a roll motion oscillator to evaluate the influence of the ship motion on the water propagation and the associated damage stability. The model tests presented in this paper comprise side leaks in typical compartments which are used for a basic validation of the simulation toll and the measurement devices. Particular attention has been drawn on damage scenarios with critical intermediate flooding stages in consequence of restricted water propagation. The presented results enable a further validation of the numerical flooding simulation and give an insight view on the chosen experimental setup.

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