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Designs, Volume 4, Issue 4 (December 2020) – 14 articles

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Open AccessArticle
Bond Graph Modeling and Kalman Filter Observer Design for an Industrial Back-Support Exoskeleton
Designs 2020, 4(4), 53; https://doi.org/10.3390/designs4040053 (registering DOI) - 04 Dec 2020
Abstract
This paper presents a versatile approach to the synthesis and design of a bond graph model and a Kalman filter observer for an industrial back-support exoskeleton. Actually, the main purpose of developing a bond graph model is to investigate and understand better the [...] Read more.
This paper presents a versatile approach to the synthesis and design of a bond graph model and a Kalman filter observer for an industrial back-support exoskeleton. Actually, the main purpose of developing a bond graph model is to investigate and understand better the system dynamics. On the other hand, the design of the Kalman observer always should be based on a model providing an adequate description of the system dynamics; however, when back-support exoskeletons are considered, the synthesis of a state observer becomes very challenging, since only nonlinear models may be adopted to reproduce the system dynamic response with adequate accuracy. The dynamic modeling of the exoskeleton robotic platform, used in this work, comprises an electrical brushless DC motor, gearbox transmission, torque sensor and human trunk (biomechanical model). On this basis, a block diagram model of the dynamic system is presented and an experimental test has been carried out for identifying the system parameters accordingly. Both the block diagram and bond graph dynamic models are simulated via MATLAB and 20-sim software (bond graph simulation software) respectively. Furthermore, the possibility of employing the Kalman filter observer together with a suitable linear model is investigated. Subsequently, the performance of the proposed Kalman observer is evaluated in a lifting task scenario with the use of a linear quadratic regulator (LQR) controller with double integral action. Finally, the most important simulation results are presented and discussed. Full article
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Open AccessArticle
Wavelet Transforms of Diagnosable Signals from Ship Power Complexes in a MATLAB Environment
Designs 2020, 4(4), 52; https://doi.org/10.3390/designs4040052 - 02 Dec 2020
Viewed by 223
Abstract
The use of digital technologies in the systems of diagnostics and monitoring of units of a ship’s propulsion plant can significantly increase the efficiency and quality of assessing the technical condition of operated objects in the online mode as well as expand the [...] Read more.
The use of digital technologies in the systems of diagnostics and monitoring of units of a ship’s propulsion plant can significantly increase the efficiency and quality of assessing the technical condition of operated objects in the online mode as well as expand the class of practical problems to be solved. Digital processing of signals of complex configuration at a qualitatively new level is an indispensable condition for a critical improvement in the course of processing the current values of diagnosable parameters, increasing the reliability and trouble-free performance of a ship’s technical equipment during operation. A method of approximation has been discussed in the paper. Moreover, the paper provides an algorithm for analyzing the signal of the indicator diagram of a marine diesel engine, the spectrum of which contains high-frequency components and short-term pulses indicating deviations from the normal operating mode, the assessment of which is practically impossible with the traditionally applied methods of spectral analysis of signals. The approximation method is based on the use of wavelet analysis, which makes it possible to deeply explore such modes. Examples of using wavelet analysis to approximate one-dimensional signals of elements and systems of a ship’s power complexes are given. Full article
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Open AccessArticle
Dual-Input Photovoltaic System Based on Parallel Z-Source Inverters
Designs 2020, 4(4), 51; https://doi.org/10.3390/designs4040051 (registering DOI) - 01 Dec 2020
Viewed by 206
Abstract
This paper aims to present a new structure of the parallel Z-source inverters (ZSIs) for dual-input single-phase grid-connected photovoltaic (PV) systems. The ZSI is a single-stage buck-boost converter that uses an inductor-capacitor network between the inverter bridge and the PV string and follows [...] Read more.
This paper aims to present a new structure of the parallel Z-source inverters (ZSIs) for dual-input single-phase grid-connected photovoltaic (PV) systems. The ZSI is a single-stage buck-boost converter that uses an inductor-capacitor network between the inverter bridge and the PV string and follows the maximum power point by applying the shoot-through vector. Therefore, a DC/DC converter is no longer needed to track the maximum power point, and the cost and complexity of the power conditioning system (PCS) are reduced. For controlling the proposed PCS, a cascade control structure is employed in this paper. The inner current loop injects the maximum active power with unity power factor sinusoidal current to the grid. The outer capacitor voltage loop is applied to control capacitors voltages in the Z-source networks. Additionally, an enhanced dual-string maximum power point tracking (eDS-MPPT) method is proposed to find MPPs with minimum burden competitional. The eDS-MPPT does not need the PVs voltages measurements compared to other MPPT methods. The simulation results confirm the accuracy of the performance of the system. Full article
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Open AccessArticle
The Economics of Classroom 3-D Printing of Open-Source Digital Designs of Learning Aids
Designs 2020, 4(4), 50; https://doi.org/10.3390/designs4040050 - 29 Nov 2020
Viewed by 243
Abstract
While schools struggle financially, capital for purchasing physical learning aids is often cut. To determine if costs could be reduced for learning aids, this study analyzed classroom-based distributed digital manufacturing using 3-D printing of open-source learning aid designs. Learning aid designs are analyzed [...] Read more.
While schools struggle financially, capital for purchasing physical learning aids is often cut. To determine if costs could be reduced for learning aids, this study analyzed classroom-based distributed digital manufacturing using 3-D printing of open-source learning aid designs. Learning aid designs are analyzed in detail for their economic viability considering printing and assembly costs with purchased components and compared to equivalent or inferior commercial products available on Amazon. The results show current open-source 3-D printers are capable of manufacturing useful learning aids and that doing so provides high economic savings in the classroom. Overall, the average learning aid would save teachers 86% when fabricating it themselves. The results show that the average design evaluated was downloaded over 1,500 times and the average savings per year per open-source learning aid design was USD 11,822. To date, the 38 learning aid designs evaluated in this study saved over USD 45,000 each and the total of all of them saved the international educational community over USD 1.7 million. It is clear that investing in the development of open-source learning aids for students provides a return on investment (ROI) for investors hoping to improve education, on average, of more than 100%. Full article
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Open AccessArticle
The Effects of Structural Breaks on Energy Resources in the Long Run. Evidence from the Last Two Oil Price Crashes before COVID-19
Designs 2020, 4(4), 49; https://doi.org/10.3390/designs4040049 - 26 Nov 2020
Viewed by 249
Abstract
The course of events since 2014, including the worldwide pandemic of a coronavirus disease, have shown that oil market fundamentals have not always been clearly anticipated and that additional external factors, rather than those related to supply and demand, do play important roles [...] Read more.
The course of events since 2014, including the worldwide pandemic of a coronavirus disease, have shown that oil market fundamentals have not always been clearly anticipated and that additional external factors, rather than those related to supply and demand, do play important roles in signaling future price changes. Within that complex setting, this study examined the influences of structural breaks on the long-term properties of Brent crude oil, gasoil, low-sulfur fuel oil, natural gas, and coal over the period 2002–2018. In an effort to assess the impacts of these structural changes, we identified time points at which structural break changes occurred and unit root properties using a representative variety of unit root testing alternatives. From the estimation results, we observed that only fuel oil and national balancing point (NBP) prices show evidence of mean-reverting behavior, suggesting that shocks to these two markets are short-lived when allowing for structural breaks. Although the idea of market forces bringing the non-renewable markets to their equilibrium in the long run makes the role of policy-making more challenging, it highlights the importance of the policy mix in the transition to a low-carbon energy system. Full article
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Open AccessArticle
An Efficient Testing Scheme for Power-Balanceability of Power System Including Controllable and Fluctuating Power Devices
Designs 2020, 4(4), 48; https://doi.org/10.3390/designs4040048 - 25 Nov 2020
Viewed by 159
Abstract
Renewable power sources are environmentally friendly power generation systems, such as wind turbines or photovoltaics; however, the output power fluctuations due to the intermittence and variability of these power systems can greatly affect the quality and stability of the power system network. Furthermore, [...] Read more.
Renewable power sources are environmentally friendly power generation systems, such as wind turbines or photovoltaics; however, the output power fluctuations due to the intermittence and variability of these power systems can greatly affect the quality and stability of the power system network. Furthermore, the power fluctuations that are triggered by power load devices also have similar results on the power system. Therefore, it is essential to introduce power level control for controllable power devices and connection in order to lessen the effects of dynamic power fluctuations that are caused by fluctuating power source devices and load devices. The issue of power balancing as a part of power level control presented in this paper assigns power levels to controllable power devices and connections between power source devices and load devices to absorb dynamic power fluctuations. In this paper, we focus on power conservation law instead of detailed voltage or current-based network characterization and present a new power balanceability test for a power flow system that comprises of both fluctuating and controllable power devices. Our proposed power balanceability test can assure the existence of a power flow assignment of power devices and connections for any value of power generation and/or the consumption of fluctuating power devices. Our proposed power balanceability test method can be expressed as a linear programming problem, and it can be resolved in polynomial time complexity. Full article
(This article belongs to the Special Issue Planning for Home Renewable Energy Systems)
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Open AccessArticle
Sympérasmology: A Proposal for the Theory of Synthetic System Knowledge
Designs 2020, 4(4), 47; https://doi.org/10.3390/designs4040047 - 05 Nov 2020
Viewed by 313
Abstract
Owing to the results of research in system science, artificial intelligence, and cognitive engineering, engineered systems are becoming more and more powered by knowledge. Complementing common-sense and scientific knowledge, system knowledge is maturing into a crucial productive asset. However, an overall theory of [...] Read more.
Owing to the results of research in system science, artificial intelligence, and cognitive engineering, engineered systems are becoming more and more powered by knowledge. Complementing common-sense and scientific knowledge, system knowledge is maturing into a crucial productive asset. However, an overall theory of the knowledge of intellectualized systems does not exist. Some researchers suggest that time has come to establish a philosophically underpinned theoretical framework. This motion is seconded by the on-going intelligence revolution, in which artificial intelligence becomes a productive power, enabler of smart systems, and a strong transformer of the social life. The goal of this paper is to propose a skeleton of the needed generic theory of system knowledge (and a possible new branch of philosophical studies). The major assumption is that a significant part of the synthetic system knowledge (SSK) is “sympérasma”, that is, knowledge conjectured, inferred, constructed, or otherwise derived during the operation of systems. This part will become even more dominant in the future. Starting out from the above term, the paper suggests calling this theory “sympérasmology”. Some specific domains of “sympérasmological” studies, such as (i) manifestations of SSK, (ii) mechanisms of generating SSK, (iii) dependability of SSK, (iv) operational power of SSK, (v) composability of SSK, and (vi) advancement of SSK, are identified. It is understood that the essence and status of SSK cannot be investigated without considering the related cognitive processes and technological enablers. The paper presents a number of open questions relevant for follow-up discussions. Full article
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Open AccessArticle
Hourly Firewood Consumption Patterns and CO2 Emission Patterns in Rural Households of Nepal
Designs 2020, 4(4), 46; https://doi.org/10.3390/designs4040046 - 04 Nov 2020
Viewed by 323
Abstract
Nepal has low per-capita energy use and a majority of its rural residents use firewood as their primary energy source. Excessive use of firewood in improperly ventilated buildings degrades the indoor environment and health condition of the inhabitants. This study aims to assess [...] Read more.
Nepal has low per-capita energy use and a majority of its rural residents use firewood as their primary energy source. Excessive use of firewood in improperly ventilated buildings degrades the indoor environment and health condition of the inhabitants. This study aims to assess the influence of hourly firewood consumption patterns on CO2 emissions and resulting concentrations in rural households in Nepal. A field survey was conducted for 24 h in 16 households during winter. The results suggest that most of the households tend to use more firewood during the morning and evening hours. Family size and number of animals reared by the households were positively correlated with firewood consumption, whereas family size was negatively correlated with per-capita firewood consumption. Per-capita firewood consumption was found to be 1.8 kg/(capita·day). Household firewood consumption and CO2 emissions were 12 kg/(family·day) and 14.26 kg CO2 e/(household·day), respectively. The larger households spent more time for cooking, while their consumption rate was similar (1.3 kg/h) to that of smaller households. High indoor CO2 emissions in the morning and evening hours due to high firewood consumption may pose severe health risks to the inhabitants. Therefore, intensive awareness programs and pollution control programs are suggested for improving indoor air quality and health condition of the rural population. Full article
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Open AccessArticle
Old Buildings’ Façades: Fieldwork and Discussion of Thermal Retrofitting Strategies in a Mediterranean Climate
Designs 2020, 4(4), 45; https://doi.org/10.3390/designs4040045 - 28 Oct 2020
Viewed by 341
Abstract
This work is within the scope of thermal retrofitting, applied to old buildings’ façades (built between 1700 and 1960) located in Mediterranean climates, such as Portugal. The aim is to increase the sustainability of existing buildings, by reducing their energy consumption needs, for [...] Read more.
This work is within the scope of thermal retrofitting, applied to old buildings’ façades (built between 1700 and 1960) located in Mediterranean climates, such as Portugal. The aim is to increase the sustainability of existing buildings, by reducing their energy consumption needs, for heating and cooling, and the corresponding gaseous emissions, while increasing their users’ comfort. Firstly, an analysis of the advantages and disadvantages of several thermal insulation solutions for façades was carried out, supported in current literature. Then, a survey of real retrofitting scenarios and interviews with experts was completed, to allow the selection of the most adequate thermal insulation techniques. Finally, as a result of this study, the discussion of retrofitting strategies was carried out to support the designer’s decision process, based on a flowchart with complementary tables, discussing the best thermal retrofitting technique to be implemented on old buildings’ façades, case-by-case. Full article
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Open AccessArticle
Empowering Design Based on Hybrid TwinTM: Application to Acoustic Resonators
Designs 2020, 4(4), 44; https://doi.org/10.3390/designs4040044 - 15 Oct 2020
Viewed by 356
Abstract
In the framework of civil aviation noise levels are becoming restricted every year, on one hand to provide comfort to the passengers and on the other hand to be compliant with regulations protecting airports surroundings. New technologies are required to reduce noise to [...] Read more.
In the framework of civil aviation noise levels are becoming restricted every year, on one hand to provide comfort to the passengers and on the other hand to be compliant with regulations protecting airports surroundings. New technologies are required to reduce noise to cope with this restrictions as well as to guarantee a comfortable flight for passengers. For technological industries it is compulsory to stay competitive and keep improving the technology related to air intake acoustic liners. With an unceasingly growing market, for industries it is key to stay in the vanguard of air inlet technologies, ensuring innovation and establishing a proactive environment for future product generations. One of the main objectives in this framework is the reduction of the development time of these new technologies in all the stages of the process. In this work we focus on the design stage of a new prototype and we propose a hybrid technique enabling faster design and the reduction of development time. When designing new technologies or prototypes there are usually two constraints. On one hand, more innovative prototypes may present unconventional shapes are not accurately represented by conventional physical models. On the other hand, the available data is scarce, thus limiting the use of most innovative techniques based on the state-of-art of Artificial Intelligence. In this paper we propose a solution laying in the hybrid twin paradigm, combining both, data in the low limit and physics to provide a hybrid model able to represent unconventional and innovative acoustic solutions. Full article
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Open AccessArticle
Proposal of an Alternative to the AMA Guidelines for the Evaluation of the Cervical ROM
Designs 2020, 4(4), 43; https://doi.org/10.3390/designs4040043 - 09 Oct 2020
Viewed by 459
Abstract
The cervical spine is one of the most frequently injured joints in a car accident. References for the range of motion (ROM) that should be expected in a person are needed to stage the injuries. The two main objectives of this paper are [...] Read more.
The cervical spine is one of the most frequently injured joints in a car accident. References for the range of motion (ROM) that should be expected in a person are needed to stage the injuries. The two main objectives of this paper are to clinically validate a measuring device for the cervical spine, and to assess if the use of different ROM reference values will render different results from the American Medical Association (AMA) ROM guidelines. The present study is divided into 2 phases, a validation phase with 55 subjects and a case-control phase with 80 subjects. A BTS (Bioengineering Technology and System) system and the EBI-5 (estudio biomecánico integral) system were used for the present investigation. The intraclass correlation agreement value between both measuring devices is considered very good with a Cronbach alpha up to 0.9 in every dimension. Correlations (r) between variables are very high, not showing any values lower than 0.887. All comparisons between using AMA ROM guidelines or normative values presented significant differences (p < 0.05). The EBI-5 system has exhibited good accuracy being paired to a photogrammetric system. The use of guidelines adjusted to age constitute an alternative to the use of the AMA cervical ROM guidelines. Professionals should use age-normalized guidelines as an alternative to the AMA guidelines. Full article
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Open AccessArticle
Bearing Fault Analysis of BLDC Motor for Electric Scooter Application
Designs 2020, 4(4), 42; https://doi.org/10.3390/designs4040042 - 03 Oct 2020
Viewed by 427
Abstract
In this paper, the bearing faults analysis of the brushless DC motor is presented. The research method is based on the analysis of the vibration signal of healthy as well as faulty bearings by the identification of specific frequencies on the vibration spectrum. [...] Read more.
In this paper, the bearing faults analysis of the brushless DC motor is presented. The research method is based on the analysis of the vibration signal of healthy as well as faulty bearings by the identification of specific frequencies on the vibration spectrum. For the experiment, the most common faults were inflicted on the bearings. As the used motor is intended for electric scooter applications, seven different damages were chosen, which are highly likely to occur during the scooter operation. The main bearing faults and the possibility of fault monitoring are addressed. The vibration data are gathered by the acceleration sensors placed on the motor at different locations and the spectrum analysis is performed using the fast Fourier transform. The variation in the amplitude of the frequency harmonics particularly the fundamental component is presented as a fault indicator. Full article
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Open AccessArticle
A Novel Digital Design Approach for Metal Additive Manufacturing to Address Local Thermal Effects
Designs 2020, 4(4), 41; https://doi.org/10.3390/designs4040041 - 01 Oct 2020
Viewed by 554
Abstract
The reliability and performance qualification of additively manufactured metal parts is critical for their successful and safe use in engineering applications. In current powder-bed fusion type metal additive manufacturing processes, local thermal accumulations affect material microstructure features, overall part quality and integrity, as [...] Read more.
The reliability and performance qualification of additively manufactured metal parts is critical for their successful and safe use in engineering applications. In current powder-bed fusion type metal additive manufacturing processes, local thermal accumulations affect material microstructure features, overall part quality and integrity, as well as bulk mechanical behavior. To address such challenges, the investigation presented in this manuscript describes a novel digital design approach combining topology optimization, process simulations, and lattice size optimization to address local thermal effects caused during manufacturing. Specifically, lattices are introduced in regions of topology optimized geometries where local thermal accumulations are predicted using the process simulations with the overall goal to mitigate high thermal gradients. The results presented demonstrate that the proposed digital design approach reduces local thermal accumulations while achieving target mechanical performance metrics. A discussion on how post-manufacturing heat treatment effects could be also considered, as well as comments on the computational implementation of the proposed approach are provided. Full article
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Open AccessArticle
The Integration of Vacuum Insulated Glass in Unitized Façade for the Development of Innovative Lightweight and Highly Insulating Energy Efficient Building Envelope—The Results of Eensulate Façade System Design
Designs 2020, 4(4), 40; https://doi.org/10.3390/designs4040040 - 24 Sep 2020
Viewed by 545
Abstract
The European Commission has identified the building industry as one of the key sectors to achieve its 2020 strategy to create conditions for smart, sustainable, and inclusive growth. In this frame, the aim of Horizon 2020′s Eensulate project is the development of innovative [...] Read more.
The European Commission has identified the building industry as one of the key sectors to achieve its 2020 strategy to create conditions for smart, sustainable, and inclusive growth. In this frame, the aim of Horizon 2020′s Eensulate project is the development of innovative lightweight and highly insulating energy efficient unitized building façades, suitable for both new and existing buildings. The Eensulate façade module integrates two components developed within the project: Vacuum Insulated Glass (VIG) for architectural purposes, with a U-value of 0.3 W/sqm∙K; a highly insulating foam for automated manufacturing and insulation for the spandrel part. This article presents the Eensulate façade system design simulations and achievements related to VIG integration to solve issues that emerged by the utilization of its innovative components (sealant thermal bridge and getter strips). VIG design and testing have gradually changed the façade module and consequently, façade components have been progressively designed to achieve the expected target of 0.641 W/sqm∙K for thermal transmittance. The results demonstrate that the target can be achieved by aluminum profiles, Ethylene Propylene Diene Monomer (EPDM) thermal bridge, and additional insulating components, obtaining a new product for unitized façades able to reduce energy consumption in buildings with large glass surfaces. Full article
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