416 research outputs found
Global Trends in the Status of Bird and Mammal Pollinators
Get PDFBiodiversity is declining, with direct and indirect effects on ecosystem func-tions and services that are poorly quantified. Here, we develop the first globalassessment of trends in pollinators, focusing on pollinating birds and mam-mals. A Red List Index for these species shows that, overall, pollinating birdand mammal species are deteriorating in status, with more species movingtoward extinction than away from it. On average, 2.5 species per year havemoved one Red List category toward extinction in recent decades, represent-ing a substantial increase in the extinction risk across this set of species. Thismay be impacting the delivery of benefits that these species provide to people.We recommend that the index be expanded to include taxonomic groups thatcontribute more significantly to pollination, such as bees, wasps, and butter-flies, thereby giving a more complete picture of the state of pollinating speciesworldwide
Damage Diagnostics of a Composite Single-Stiffener Panel Under Fatigue Loading Utilizing SHM Data Fusion
No full textA case study is presented in which the first steps are made towards the development of a structural health monitoring (SHM) data fusion framework. For this purpose, a composite single-stiffener panel is subjected to compression-compression fatigue loading (R = 10). The carbon-epoxy panel contains an artificial disbond of 30 mm, which was created using a Teflon insert during manufacturing and placed between the skin and the stiffener foot. Under the applied fatigue load, the disbond is expected to grow and its propagation is monitored using two SHM techniques, namely acoustic emission (AE) and Rayleigh-scattering based distributed fiber optic strain sensing. Four AE sensors are placed on the skin, thereby allowing for disbond growth detection and localization. On each stiffener foot, fiber optic sensors are surface-bonded to monitor the growth of the disbond under the applied fatigue loading. The distributed strain measurements are used to localize and monitor the disbond growth. The strength of each technique is utilized by fusing the data from the AE sensors and the fiber optic sensors. In this manner, a data-driven approach is presented in which a data fusion of the different techniques allows for monitoring the damage in the stiffened panel on multiple SHM levels, including disbond growth detection and localization.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Structural Integrity & Composite
A Strain-Based Health Indicator for the SHM of Skin-to-Stringer Disbond Growth of Composite Stiffened Panels in Fatigue
No full textReal-time Structural Health Monitoring (SHM) of aeronautical structural components is a technology persistently investigated the last years by researchers and engineers to potentially reduce the cost and/or implementation of scheduled maintenance tasks. To this end, various types of sensors have been proposed to serve this role, e.g. piezoelectric, acoustic emission, and strain sensors. In the present paper, a strain-based SHM methodology is proposed for skin/stringer disbond propagation health monitoring. Fiber-optic strain sensors with engraved Bragg gratings are utilized in order to evaluate the propagation of artificially-induced disbonds at single-stringered composite panels. The specimens are subjected to a block loading compression-compression fatigue spectrum. Longitudinal static strains are periodically acquired during quasi-static loadings every 500 cycles. A Health Indicator (HI), based on strains received from the stringer’s feet, is proposed and utilized to monitor the disbond growth. The evolution of this indicator is experimentally monitored throughout the lifespan of the specimens. The present paper verifies and consolidates via actual fatigue experiments the potential of the proposed static-strain based HI developed from numerical data in our previous work.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Structural Integrity & Composite
An SHM Data-Driven Methodology for the Remaining Useful Life Prognosis of Aeronautical Subcomponents
No full textPrognosis of the Remaining Useful Life (RUL) of a structure from Structural Health Monitoring data is the ultimate level in the SHM hierarchy. Reliable prognostics are key to a Condition Based Maintenance paradigm for aerospace systems and structures. In the present work, we propose a methodology for RUL prognosis of generic aeronautical elements i.e. single stringered composite panels subjected to compression/compression fatigue. Strain measurements are utilized in this direction via FBG sensors bonded to the stiffener feet. The strain data collected during the fatigue life are processed and used for the RUL prognosis. In order to accomplish this task, it is essential to produce Health Indicators (HIs) out of raw strain that can properly capture the degradation process. To create such HIs a new pre/post-processing technique is employed and a variety of different HIs are developed. The quality of the HIs can enhance the performance of the prognostic algorithms, hence a fusion methodology is proposed using genetic algorithms. The resulted fused HI is used for the RUL estimation of the SSCPs. Gaussian processes and Hidden Semi Markov Models are employed for RUL prognosis and their performance is compared. Despite the complexity the raw data we demonstrate the feasibility of successful RUL prognostics in a SHM-data driven approach.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Structural Integrity & Composite
Evaluation of business process in convention production companies using business process improvement (BPI)
Get PDFThis research aims to choose the best business process model for a convection company during the COVID-19 pandemic. This study applies an analytical framework of business process improvement (BPI), including five whys analysis (organizing for improvement, understanding the process, streamlining, measurement and controls, continuous improvement). Model business process modeling and notation (BPMN). The results of this study are an analysis of business processes that occur in convection companies, and the results are that the business processes in convection companies are still less effective. In addition, the author also provides recommendations, namely the use of a database on the ordering system used evaluation of business processes in convection production companies using BPI and BPMN
Application design for web-based car services to increase work time estimates
No full textThe aim of this research is to increase the estimated service process time by creating an online-based car service ordering application at the Sinar Jaya repair shop and introducing information about Sinar Jaya car service services to the wider public. In this information systems research, the author of this research software development method uses the waterfall model development method. By implementing a waterfall, the research stages carried out by researchers start from data analysis, system analysis, system design, implementation, and testing. Creating a website-based car service ordering application at the Sinar Jaya Workshop can help customers find out the information available at the Sinar Jaya Workshop and the car service ordering process. Before there was an application, customers had to come to the location to place an order, so it took a long time to arrive at the location. So, with the online booking application, you can save time in the service process and get a queue number online. The data processing process for ordering car services becomes more practical so that it can be processed properly by the admin
Planning low-error SHM strategy by constrained observability method
Get PDFStructural identification using dynamical parameters (such as the natural vibration frequencies and mode shapes) is an important issue, especially in bridges or high-rise buildings. However, incorrect decisions could happen on the Structural Health Monitoring (SHM) strategy and the Structural System Identification (SSI) analysis that makes the sometimes expensive and time-consuming process useless due to the large uncertainty of the resulting estimations. This paper discusses the role of the SHM strategy and the SSI analysis based on the constrained observability method (COM) and decision trees (DT) in reducing the estimation error. Here, the COM uses subsets of natural frequencies and/or modal-shapes to deal with the nonlinearity of the SSI derived from the operational aspects of the methods, and combines the unknown items including frequencies and mode shapes into an optimization process. Next, a decision-support tool based on decision trees is applied to help engineers to establish the best SHM + SSI strategy yielding the most accurate estimations. The principle and steps of this new method, the combination of constrained observability m,ethod and decision trees, are presented for the first time. After that, a numerical model of a bridge case is used to show how to choose the optimal strategy, when factors such as the structure layout, span length, measurement set, and parameters of the COM are included as decision variables. The importance ranking of these four factors is the layout, measurement set, parameters of the COM, and length through the sensitivity analysis of the COM estimated. Last, a real bridge is used to validate this methodology under the undamaged and damaged scenarios by comparing an Error Index, which shows the optimal SHM + SSI strategy works well no matter the bridge is damaged or not. The presented analysis leads to significant insights that can help the decision-making of the optimal SHM + SSI strategy, avoiding erroneous decisions if this tool is not used beforehand.Integral Design & Managemen
Performance Analysis of Wi-Fi Wireless Networks In A Vortex Media Access And Reseller Broadband
Get PDFThe research aims to analyze network performance in an office and also a broadband reseller, to determine network quality through monitoring trials on servers and clients. The research uses data collection methods by conducting interviews. The second stage is needs analysis as a benchmark for network performance analysis. The next stage is monitoring the server and client to determine network speed. From research that has been carried out related to the analysis of WiFi wireless networks in small and medium office environments using custom network topology to suit needs, as well as broadband resellers also using custom network topology. The distribution of bandwidth from each place adjusts to their respective needs to get quality network connections The good thing is, that there are no specific standards for dividing bandwidth, it all depends on needs. The results of the data obtained from the analysis of the two places, of course from the analysis that the author has carried out, we can know the quality of the network connection from the two places, apart from that the topology design used by the office environment and also broadband resellers can increase knowledge about WiFi wireless networks and can be an example to open a business in the field of WiFi wireless networks that can provide faster WiFi performance with wider coverage
Design and building system analysis on the smart fisheries village (SFV) website at the banyuwangi fisheries training and counseling center
Get PDFThis research aims to analyze and design a smart fisheries village-based website system to facilitate back-end, front-end, and UI/UX designers in the application of website creation according to the needs desired by the agency and with an organized database so that the creation of data reports will be faster. The early stages of the research began with the identification of the the specific needs of fishing villages and involved an in-depth analysis of the system needs that supported the vision of the Smart Fisheries Village. The design began with data collection consisting of observation methods and interviews, where researchers interviewed the authorities. In this method, the author gives 5 questions to the user, data analysis, and design of the Unified Modeling Language (UML). The design of this SFV web system uses a Unified Modeling Language (UML), which involves the use of diagrams and UML notation to describe various aspects of the system visually. The results of this study include UML diagrams, which encompass activity diagrams (for users and admins), flow diagrams (for users and admins), use case diagrams (for users and admins), and class diagrams that have undergone 4-5 iterations. The design of the Smart Fisheries Village website system is necessary to improve the welfare of the fishing village. Contributions of this research include the standardization of modeling, increased productivity, improved analysis and planning, and improved understanding. Previous research might have concentrated on a single type of system or domain. However, research should be expanded to various types of systems and industries
On the Challenges of Upscaling Damage Monitoring Methodologies for Stiffened Composite Aircraft Panels
No full textHealth management methodologies for condition-based maintenance are often developed using sensor data collected during experimental tests. Most tests performed in laboratories focus on a coupon level or flat panels, while structural component testing is less commonly seen. As researchers, we often consider our experimental tests to be representative of a structure in a final application and consider the developed methodologies to be transferrable to these real-life structures. Yet, structures in their final applications such as wind turbines or aircraft are often larger, more complex, might contain various assembly details, and are loaded in complex conditions. These factors might influence the performance of developed diagnostic and prognostic methodologies and should therefore not be ignored.In our work, we consider the aspects of upscaling structural health monitoring (SHM) methodologies for stiffened composite panels with the design of the panels inspired by an aircraft wing structure. For this, we examine two levels of panels, namely a single- and multi-stiffener composite panel, where we consider the single-stiffener panel to be a representative lower-level version of the multi-stiffener panel. Multiple SHM sensors (acoustic emission, Lamb waves, strain sensing) were installed on both composite panels to monitor damage propagation during testing. We identify and analyse challenges and further discuss considerations that must be taken during upscaling of diagnostics and prognostics, and with that, aid in the development of health management methodologies for condition-based maintenance.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Structural Integrity & Composite
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