scholarly journals An Introduction to Indoor Localization Techniques. Case of Study: A Multi-Trilateration-Based Localization System with User–Environment Interaction Feature

2021 ◽  
Vol 11 (16) ◽  
pp. 7392
Author(s):  
Bruno Andò ◽  
Salvatore Baglio ◽  
Ruben Crispino ◽  
Vincenzo Marletta
Keyword(s):  
System Architecture ◽  
Indoor Localization ◽  
State Of The Art ◽  
Operating Conditions ◽  
Environment Interaction ◽  
End User ◽  
Localization System ◽  
Wide Range ◽  
Continuous Estimation

The problem of estimating the indoor position of a person or an object, also known as indoor localization, has gained a lot of interest in the last decades. Actually, this feature would be valuable in many application contexts, from logistics to robotic and Assistive Technology. Different solutions have been proposed in the literature, exploiting a wide range of approaches. This paper aims to provide a brief review of the state-of-the-art approaches in the field, as well as to present the RESIMA case study. The latter exploits an ultrasound-based indoor localization system and a User–Environment Interaction functionality, which allows for performing the continuous estimation of the distance between the end-user and objects in the environment. The latter is valuable to provide the end-user with efficient assistance during the environment exploitation. The main focus of this work is related to the overall description of the system architecture, the trilateration algorithm adopted for the sake of user localization and the estimation of the delay time produced by user-distance computation under different operating conditions.

A State-of-the-Art CFD Setup for Axial Compressors: Details and Validation

2020 ◽  
Author(s):  
Lorenzo Cozzi ◽  
Filippo Rubechini ◽  
Andrea Arnone ◽  
Savino Depalo ◽  
Pio Astrua ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Power Plants ◽  
State Of The Art ◽  
Secondary Flows ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Cfd Modelling ◽  
Axial Compressors ◽  
Surge Margin ◽  
Wide Range

Abstract The overall fraction of the power produced by renewable sources in the energy market has significantly increased in recent years. The power output of most of these clean sources is intrinsically variable. At present day and most likely in the upcoming future, due to the lack of inexpensive and reliable large energy storage systems, conventional power plants burning fossil fuels will still be part of the energy horizon. In particular, power generators able to promptly support the grid stability, such as gas turbines, will retain a strategic role. This new energy scenario is pushing gas turbine producers to improve the flexibility of their turbomachines, increasing the need for reliable numerical tools adopted to design and validate the new products also in operating conditions far from the nominal one. Especially when dealing with axial compressors, i.e. machines experiencing intense adverse pressure gradients, complex flow structures and severe secondary flows, CFD modelling of offdesign operation can be a real challenge. In this work, a state-of-the art CFD framework for RANS analysis of axial compressors is presented. The various aspects involved in the whole setup are discussed, including boundary conditions, meshing strategies, mixing planes modelling, tip clearance treatment, shroud leakages and turbulence modelling. Some experiences about the choice of these aspects are provided, derived from a long-date practice on this kind of turbomachines. Numerical results are reported for different full-scale compressors of the Ansaldo Energia fleet, covering a wide range of operating conditions. Furthermore, details about the capability of the setup to predict compressor performance and surge-margin have been added to the work. In particular, the setup surge-margin prediction has been evaluated in an operating condition in which the turbomachine experiences experimental stall. Finally, thanks to several on-field data available at different corrected speeds for operating conditions ranging from minimum to full load, a comprehensive validation of the presented numerical framework is also included in the paper.

scholarly journals Flux-Reducing Tendency of Pd-Based Membranes Employed in Butane Dehydrogenation Processes

Membranes ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 291 ◽  
Author(s):  
Thijs A. Peters ◽  
Marit Stange ◽  
Rune Bredesen
Keyword(s):  
Competitive Adsorption ◽  
Prolonged Exposure ◽  
Hydrogen Permeation ◽  
State Of The Art ◽  
Operating Temperature ◽  
Operating Conditions ◽  
Maximum Temperature ◽  
Hydrogen Flux ◽  
Membrane Performance ◽  
Wide Range

We report on the effect of butane and butylene on hydrogen permeation through thin state-of-the-art Pd–Ag alloy membranes. A wide range of operating conditions, such as temperature (200–450 °C) and H2/butylene (or butane) ratio (0.5–3), on the flux-reducing tendency were investigated. In addition, the behavior of membrane performance during prolonged exposure to butylene was evaluated. In the presence of butane, the flux-reducing tendency was found to be limited up to the maximum temperature investigated, 450 °C. Compared to butane, the flux-reducing tendency in the presence of butylene was severe. At 400 °C and 20% butylene, the flux decreases by ~85% after 3 h of exposure but depends on temperature and the H2/butylene ratio. In terms of operating temperature, an optimal performance was found at 250–300 °C with respect to obtaining the highest absolute hydrogen flux in the presence of butylene. At lower temperatures, the competitive adsorption of butylene over hydrogen accounts for a large initial flux penalty.

Analysis of the Rotordynamic Response of a Centrifugal Compressor Subject to Aerodynamic Loads due to Rotating Stall

2014 ◽  
Author(s):  
Davide Biliotti ◽  
Alessandro Bianchini ◽  
Giuseppe Vannini ◽  
Elisabetta Belardini ◽  
Marco Giachi ◽  
...  
Keyword(s):  
Excitation Frequency ◽  
Load Condition ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Range Analysis ◽  
Radial Vibrations ◽  
Aerodynamic Loads ◽  
Flow Limit ◽  
Wide Range

In the current industrial research on centrifugal compressors, manufacturers are showing increasing interest in the extension of the minimum stable flow limit in order to improve the operability of each unit. The aerodynamic performance of a compressor stage is indeed often limited before surge by the occurrence of diffuser rotating stall. This phenomenon generally causes an increase of the radial vibrations, which, however, is not always connected with a remarkable performance detriment. In case the operating curve has been limited by a mechanical criterion, i.e. based on the onset of induced vibrations, an investigation on the evolution of the aerodynamic phenomenon when the flow rate is further reduced can provide some useful information. In particular, the identification of the real thermodynamic limit of the system could allow one to verify if the new load condition could be tolerated by the rotordynamic system in terms of radial vibrations. Within this context, recent works showed that the aerodynamic loads due to a vaneless diffuser rotating stall can be estimated by means of test-rig experimental data of the most critical stage. Moreover, by including these data into a rotordynamic model of the whole machine, the expected vibration levels in real operating conditions can be satisfactorily predicted. To this purpose, a wide-range analysis was carried out on a large industrial database of impellers operating in presence of diffuser rotating stall; the analysis highlighted specific ranges for the resultant rotating force in terms of intensity and excitation frequency. Moving from these results, rotordynamic analyses have been performed on a specific case study to assess the final impact of these aerodynamic excitations.

scholarly journals Deploying CommunityCommands: A Software Command Recommender System Case Study

AI Magazine ◽  
2015 ◽  
Vol 36 (3) ◽  
pp. 19-34
Author(s):  
Wei Li ◽  
Justin Matejka ◽  
Tovi Grossmann ◽  
George Fitzmaurice
Keyword(s):  
Recommender System ◽  
System Architecture ◽  
Design Space ◽  
User Study ◽  
End User ◽  
Software Application ◽  
Customer Involvement ◽  
Learning Assistance ◽  
One Year

In 2009 we presented the idea of using collaborative filtering within a complex software application to help users learn new and relevant commands (Matejka et al. 2009). This project continued to evolve and we explored the design space of a contextual software command recommender system and completed a six-week user study (Li et al. 2011). We then expanded the scope of our project by implementing CommunityCommands, a fully functional and deployable recommender system. CommunityCommands was a publically available plug-in for Autodesk’s flagship software application AutoCAD. During a one-year period, the recommender system was used by more than 1100 users. In this article, we discuss how our practical system architecture was designed to leverage Autodesk’s existing Customer Involvement Program (CIP) data to deliver in-product contextual recommendations to end-users. We also present our system usage data and payoff, and provide an in-depth discussion of the challenges and design issues associated with developing and deploying the software command recommender system. Our work sets important groundwork for the future development of recommender systems within the domain of end-user software learning assistance.

scholarly journals Indoor Localization System Using Wi-Fi Technology

2019 ◽  
pp. 69-77
Keyword(s):  
Global Positioning System ◽  
Indoor Localization ◽  
Tracking System ◽  
Low Cost ◽  
Positioning System ◽  
Test Results ◽  
Localization System ◽  
Transmission Technique ◽  
Wide Range ◽  
Global Positioning

Recently, indoor localization has witnessed an increase in interest, due to the potential wide range of using in different applications, such as Internet of Things (IoT). It is also providing a solution for the absence of Global Positioning System (GPS) signals inside buildings. Different techniques have been used for performing the indoor localization, such as sensors and wireless technologies. In this paper, an indoor localization and object tracking system is proposed based on WiFi transmission technique. It is done by distributing different WiFi sources around the building to read the data of the tracked objects. This is to measure the distance between the WiFi receiver and the object to allocate and track it efficiently. The test results show that the proposed system is working in an efficient way with low cost.

scholarly journals Improving Indoor Localization System Using a Partitioning Technique Based on RSS and ToA

2021 ◽  
Vol 3 (1) ◽  
pp. 47-54
Author(s):  
Mahmood F . Mosleh ◽  
Faeza A. Abed ◽  
Zahraa Abbas Hamza
Keyword(s):  
Indoor Environment ◽  
Indoor Localization ◽  
Average Error ◽  
Localization System ◽  
The Real ◽  
Special Values ◽  
Case Study Area ◽  
Partitioning Technique ◽  
Interference Problems

Designing a localization system for an indoor environment faces more challenges because of multipath and interference problems. In this field, the most important techniques used for such environment, are RSS and ToA which need to be improved especially from more interference because of the huge multipath problems. In this paper, a case study of a selected building is chosen in order to apply the proposed technique of this research. Such proposal is based on the PT ‎ of the area in the case study into MZ. Each zone is allocated special values for the parameters used to estimate the target positions. WI package is used to simulate the case study area and apply such proposal based on RSS and ToA. The results confirm that the estimated locations are close to the real locations by the average error of (2.8) meter and (0.192) meter for ToA corresponding one zone and four zones ‎respectively. ‎ In contrast, the results of our experiment show that the accuracy is improved from an average error of (2.4) meter and (0.217) meter for RSS corresponding one zone and four zones ‎respectively‎. Such results confirm that dividing the case study area into more zones leads to more accuracy.

Analysis of the Rotordynamic Response of a Centrifugal Compressor Subject to Aerodynamic Loads Due to Rotating Stall

2014 ◽  
Vol 137 (2) ◽  
Author(s):  
Davide Biliotti ◽  
Alessandro Bianchini ◽  
Giuseppe Vannini ◽  
Elisabetta Belardini ◽  
Marco Giachi ◽  
...  
Keyword(s):  
Excitation Frequency ◽  
Load Condition ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Range Analysis ◽  
Radial Vibrations ◽  
Aerodynamic Loads ◽  
Flow Limit ◽  
Wide Range

In the current industrial research on centrifugal compressors, manufacturers are showing increasing interest in the extension of the minimum stable flow limit in order to improve the operability of each unit. The aerodynamic performance of a compressor stage is indeed often limited before surge by the occurrence of diffuser rotating stall. This phenomenon generally causes an increase of the radial vibrations, which, however, is not always connected with a remarkable performance detriment. In case the operating curve has been limited by a mechanical criterion, i.e., based on the onset of induced vibrations, an investigation on the evolution of the aerodynamic phenomenon when the flow rate is further reduced can provide some useful information. In particular, the identification of the real thermodynamic limit of the system could allow one to verify if the new load condition could be tolerated by the rotordynamic system in terms of radial vibrations. Within this context, recent works showed that the aerodynamic loads due to a vaneless diffuser rotating stall can be estimated by means of test-rig experimental data of the most critical stage. Moreover, by including these data into a rotordynamic model of the whole machine, the expected vibration levels in real operating conditions can be satisfactorily predicted. To this purpose, a wide-range analysis was carried out on a large industrial database of impellers operating in presence of diffuser rotating stall; the analysis highlighted specific ranges for the resultant rotating force in terms of intensity and excitation frequency. Moving from these results, rotordynamic analyses have been performed on a specific case study to assess the final impact of these aerodynamic excitations.

Advanced Components for PEMFC Stacks

2006 ◽  
Author(s):  
Chinbay Fan ◽  
Michael Onischak ◽  
William Liss
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
State Of The Art ◽  
Low Cost ◽  
Polymer Membrane ◽  
Operating Conditions ◽  
Metal Alloy ◽  
Membrane Electrode ◽  
Corrosion Rates ◽  
Wide Range

Currently, fuel cell cost reduction and long life are major priorities for fuel cells to be commercially successful for vehicle, stationary, or portable power applications. In the last five years, Gas Technology Institute (GTI) has formulated and developed a low cost, long lifetime, high conductivity proton exchange membrane (PEM) yielding state-of-the-art fuel cell performance. Additionally, a non-coated, corrosion-resistant metal alloy bipolar separator plate has been patented and tested for both hydrogen-fueled and direct methanol fueled PEMFC applications. Tests in fuel cells plus out-of-cell ASTM corrosion tests have shown very low corrosion rates under fuel cell operating conditions. Metal alloy separator plates have run for over 23,000 hours in cells with corrosion rates an order of magnitude less than the DOE target of 1 μA/cm2. GTI’s fuel cell polymer membrane research focused on three criteria: (1) use of low cost materials; (2) polymer structures stable under fuel cell operating conditions; and (3) performance equal or better than current Nafion membrane electrode assemblies (MEAs). Fluorine-containing polymers were eliminated due to cost issues, environmental factors, and the negative influence fluorine ion loss has on metallic separator plates. The polymer membrane material was synthesized and cast into films, then fabricated into MEAs. The cost of the membrane (raw materials plus film processing materials) is estimated to be less than $10/m2 — or less than 10% of available technology. A variety of out-of-cell testing showed the membrane has sufficient strength, flexibility, and conductivity to serve as an ion conducting membrane for fuel cells. A series of 60 cm2 active area single cells and short stacks were operated over a wide range of fuel cell conditions, showing state-of-the-art MEA performance with long-term polymer stability.

Extremely Low Mass Flow at High Blade to Jet Speed Ratio in Variable Geometry Radial Turbines and its Influence on the Flow Pattern: A CFD Analysis

2017 ◽  
Author(s):  
José Ramón Serrano ◽  
Antonio Gil ◽  
Roberto Navarro ◽  
Lukas Benjamin Inhestern
Keyword(s):  
Mass Flow ◽  
Flow Instability ◽  
State Of The Art ◽  
Flow Behavior ◽  
Weight Ratio ◽  
Operating Conditions ◽  
Speed Ratio ◽  
Cfd Simulations ◽  
Wide Range ◽  
Low Mass

State of the art car engines are fed by compressed air, coming from a turbocharger compressor, to increase the power to weight ratio and to allow downsizing the combustion engine. The used compressor is driven by a radial turbine taking advantage of the hot and pressurized exhaust gases of the engine. Thus, the turbine acts under highly unsteady conditions, working at very different turbine map regions. In urban driving the turbine faces even higher changes due to frequent acceleration and deceleration so that extremely low mass flow can occur. However, the flow behavior in turbocharger turbines at these extreme off-design conditions is rather unknown. So the development of physically-based models for extrapolating the usually narrow experimental turbine maps and advanced measurements to increase the range of turbine maps has been in the focus of many researchers. To provide valuable information about those flow characteristics, this paper supplies a detailed analysis at low mass flow in a radial turbocharger turbine. The turbine has been experimentally characterized under steady flow from normal operating working conditions up to extreme off-design points, where the turbine could even work with negative efficiency. Since heat transfer significantly affects the turbine efficiency calculation when turbine power is low, the experiments have been executed under quasi-adiabatic conditions and residual heat fluxes have further been corrected. This paper takes advantage of these data to validate adiabatic CFD simulations in a wide operating range, from optimum efficiency point up to negative turbine power. Stationary and transient three-dimensional CFD simulations of the turbocharger turbine have been performed. The numerical campaign covers a wide range of operating conditions, providing different flow patterns. The obtained results show that the secondary flow field changes appreciably with mass flow rate. At low mass flows, a further backflow region develops over the entire circumference close to the hub, significantly constricting the effective turbine area and provoking mass flow instability. The highlighted flow phenomena will allow to improve state of the art extrapolation models and might help designers to understand turbine flow operating under extreme off-design conditions.

A Multi-Level Modularized System Architecture for Mobile Robotics

2010 ◽  
Author(s):  
Brandon Basso ◽  
Benjamin Kehoe ◽  
J. Karl Hedrick
Keyword(s):  
System Architecture ◽  
Design Principle ◽  
Mobile Robotics ◽  
Modular System ◽  
Design Philosophy ◽  
Wide Range ◽  
Multi Agent ◽  
Multi Level ◽  
Bottom To Top

This paper describes a modular system architecture for mobile robotics. It presents the view of an individual robot as a collection of many small pieces of hardware and software grouped into functional subsystems. A set of robots can then join together to form a larger system. The goal of this work is to describe a software design philosophy and architecture that is flexible yet robust enough to meet the challenges of the mobile robotics domain. The guiding design principle is bottom-to-top modularization, from individual algorithms, to software executables, to functional groupings of executables. These functional groupings are presented as canonical subsystems for collaborative robotics, applicable to a wide range of robotics systems. A multi-agent multi-user UAV application is presented as a case study and proof of the generality of the design philosophy.

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