Next Issue
Volume 10, September-2
Previous Issue
Volume 10, August-2

Table of Contents

Appl. Sci., Volume 10, Issue 17 (September-1 2020) – 419 articles

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
Cover Story (view full-size image) In tomato greenhouse production, the labor employed in the harvesting task represents between 25% [...] Read more.
Order results
Result details
Select all
Export citation of selected articles as:
Open AccessArticle
Cooperative and Multimodal Capabilities Enhancement in the CERNTAURO Human–Robot Interface for Hazardous and Underwater Scenarios
Appl. Sci. 2020, 10(17), 6144; https://doi.org/10.3390/app10176144 - 03 Sep 2020
Viewed by 323
Abstract
The use of remote robotic systems for inspection and maintenance in hazardous environments is a priority for all tasks potentially dangerous for humans. However, currently available robotic systems lack that level of usability which would allow inexperienced operators to accomplish complex tasks. Moreover, [...] Read more.
The use of remote robotic systems for inspection and maintenance in hazardous environments is a priority for all tasks potentially dangerous for humans. However, currently available robotic systems lack that level of usability which would allow inexperienced operators to accomplish complex tasks. Moreover, the task’s complexity increases drastically when a single operator is required to control multiple remote agents (for example, when picking up and transporting big objects). In this paper, a system allowing an operator to prepare and configure cooperative behaviours for multiple remote agents is presented. The system is part of a human–robot interface that was designed at CERN, the European Center for Nuclear Research, to perform remote interventions in its particle accelerator complex, as part of the CERNTAURO project. In this paper, the modalities of interaction with the remote robots are presented in detail. The multimodal user interface enables the user to activate assisted cooperative behaviours according to a mission plan. The multi-robot interface has been validated at CERN in its Large Hadron Collider (LHC) mockup using a team of two mobile robotic platforms, each one equipped with a robotic manipulator. Moreover, great similarities were identified between the CERNTAURO and the TWINBOT projects, which aim to create usable robotic systems for underwater manipulations. Therefore, the cooperative behaviours were validated within a multi-robot pipe transport scenario in a simulated underwater environment, experimenting more advanced vision techniques. The cooperative teleoperation can be coupled with additional assisted tools such as vision-based tracking and grasping determination of metallic objects, and communication protocols design. The results show that the cooperative behaviours enable a single user to face a robotic intervention with more than one robot in a safer way. Full article
(This article belongs to the Special Issue Advances on Underwater Robotics and Automation)
Show Figures

Figure 1

Open AccessArticle
A Fast-Response Calorimeter with Dynamic Corrections for Transient Heat Transfer Measurements
Appl. Sci. 2020, 10(17), 6143; https://doi.org/10.3390/app10176143 - 03 Sep 2020
Viewed by 297
Abstract
Robust fast-response transient calorimeters with novel calorimeter elements have attracted the attention of researchers as new synthetic materials have been developed. This sensor uses diamonds as the calorimeter element, and a platinum film resistance is sputtered on the back to measure the temperature. [...] Read more.
Robust fast-response transient calorimeters with novel calorimeter elements have attracted the attention of researchers as new synthetic materials have been developed. This sensor uses diamonds as the calorimeter element, and a platinum film resistance is sputtered on the back to measure the temperature. The surface heat flux is obtained based on the calorimetric principle. The sensor has the advantages of high sensitivity and not being prone to erosion. However, non-ideal conditions, such as heat dissipation from the calorimeter element to the surroundings, can lead to measurement deviation and result in challenges for sensor miniaturization. In this study, a novel transient calorimeter (NTC) with two different sizes was developed using air or epoxy as the back-filling material. Numerical simulations were conducted to explain the complex heat exchange between the calorimeter element and its surroundings, which showed that it deviated from the assumption of an ideal calorimeter sensor. Accordingly, a dynamic correction method was proposed to compensate for the energy loss from the backside of the calorimeter element. The numerical results showed that the dynamic correction method significantly improved the measurement deviation, and the relative error was within 2.3% if the test time was smaller than 12 ms in the simulated cases. Detonation shock tunnel experiments confirmed the results of the dynamic correction method and demonstrated a practical method to obtain the dynamic correction coefficient. The accuracy and feasibility of the dynamic correction method were verified in a single detonation shock tunnel and under shock tube conditions. The NTC calorimeter exhibited good repeatability in all experiments. Full article
(This article belongs to the Special Issue Diagnostic Methodology and Sensors Technologies)
Show Figures

Figure 1

Open AccessArticle
Comparison of Neural Activation Area in Primary Somatosensory Cortex and Brodmann Area 3 According to Finger and Phalange High-Frequency Vibration Stimulation
Appl. Sci. 2020, 10(17), 6142; https://doi.org/10.3390/app10176142 - 03 Sep 2020
Viewed by 283
Abstract
In this study, we measured neuronal activation in the primary somatosensory area (S1) and Brodmann area 3 (BA3) using 3T functional magnetic resonance imaging (fMRI) while presenting a 250-Hz high-frequency vibrational stimulus to each of three phalanges (distal, intermediate, and proximal) of four [...] Read more.
In this study, we measured neuronal activation in the primary somatosensory area (S1) and Brodmann area 3 (BA3) using 3T functional magnetic resonance imaging (fMRI) while presenting a 250-Hz high-frequency vibrational stimulus to each of three phalanges (distal, intermediate, and proximal) of four fingers of the right hand (index, middle, ring, and little). We compared the nerve activation area between each finger and each phalange. Ten healthy male college students (26.6 ± 2.5 years old) participated in this study. One session consisted of three blocks: a rest (30 s), stimulation (30 s), and response phase (9 s). In the rest phase, the vibrational stimulus was not presented. In the stimulation phase, the vibrational stimulation was presented at any one of the three phalanges of the selected finger. In the response phase, subjects were instructed to press a button corresponding to the phalange that they thought had received the vibration. The subtraction method was used to extract the activation area. The activation area in the S1 was the largest when the little finger was stimulated (for the finger comparison), and largest when the second phalange was stimulated (for the phalange comparison). The BA3 showed similar trends, and there was no statistically significant difference. Full article
(This article belongs to the Section Applied Biosciences and Bioengineering)
Show Figures

Figure 1

Open AccessTechnical Note
Easy, Fast, and Accurate Method of 3-Dimensional Mirror Plane Creation for Actual Clinical Users
Appl. Sci. 2020, 10(17), 6141; https://doi.org/10.3390/app10176141 - 03 Sep 2020
Viewed by 269
Abstract
The first thing to do before planning the surgical treatment of unilateral defects or the asymmetry of the facial area is probably establishing adequate mid-plane for comparison and analysis of the normal and affected side. In such cases, a mirror image can be [...] Read more.
The first thing to do before planning the surgical treatment of unilateral defects or the asymmetry of the facial area is probably establishing adequate mid-plane for comparison and analysis of the normal and affected side. In such cases, a mirror image can be useful to obtain customized and optimized mid-plane for specific individuals considering the degree of the defect and asymmetry. With the concept of the iterative closest point (ICP) algorithm, the surface-based registration of the initial structure and mirrored structure allow us to generate a mirror plane that bisects the mid planes of each structure. This mirror plane would improve the quality of pre-operative evaluation and provide an appropriate start point for the treatment plan with as few errors as possible. Hence, the aim of this article is to introduce a method to create a mirror plane that can be assisting in increasing the accuracy of evaluation and analysis so a precise treatment plan would follow consequently. Full article
(This article belongs to the Special Issue Application of CAD/CAM and 3D Printing Technologies in Dentistry)
Show Figures

Figure 1

Open AccessArticle
Model Test and Numerical Simulation of Single Pile Response under Combined Loading in Slope
Appl. Sci. 2020, 10(17), 6140; https://doi.org/10.3390/app10176140 - 03 Sep 2020
Viewed by 282
Abstract
Vertical loads are commonly transferred by piles primarily in the upper structures. However, lateral loads are also significant compared with vertical loads in pile foundation design. Compared with a pile on level ground, there are many particular characteristics in a pile that is [...] Read more.
Vertical loads are commonly transferred by piles primarily in the upper structures. However, lateral loads are also significant compared with vertical loads in pile foundation design. Compared with a pile on level ground, there are many particular characteristics in a pile that is on sloping ground. These characteristics depend on the combined loading and the magnitude of the soil lateral displacement. In order to investigate the pile’s bearing characteristics, a model test was conducted and ABAQUS software was adopted to conduct 3D numerical simulation of a single pile with different slope angles under combined loads. The experimental results indicated that (1) the soil pressure along the slope direction was smaller than the other side, resulting in an asymmetry of the slope soil around the pile, and in turn introducing a horizontal thrust to the pile; (2) with the increase of slope angle, the horizontal thrust increased while the single pile’s bearing capacity decreased; (3) the vertical load caused more pile horizontal displacement with the growth of slope angle; and (4) the pile’s moment and the displacement also increased with the growth of the slope angle. The findings in this study can provide a useful reference in the design of piles or anti-slide piles in sloping ground. Full article
(This article belongs to the Special Issue Advances in Geotechnical Engineering)
Show Figures

Figure 1

Open AccessArticle
In Vivo Assessment of Water Content, Trans-Epidermial Water Loss and Thickness in Human Facial Skin
Appl. Sci. 2020, 10(17), 6139; https://doi.org/10.3390/app10176139 - 03 Sep 2020
Viewed by 235
Abstract
Mapping facial skin in terms of its biophysical properties plays a fundamental role in many practical applications, including, among others, forensics, medical and beauty treatments, and cosmetic and restorative surgery. In this paper we present an in vivo evaluation of the water content, [...] Read more.
Mapping facial skin in terms of its biophysical properties plays a fundamental role in many practical applications, including, among others, forensics, medical and beauty treatments, and cosmetic and restorative surgery. In this paper we present an in vivo evaluation of the water content, trans-epidermial water loss and skin thickness in six areas of the human face: cheeks, chin, forehead, lips, neck and nose. The experiments were performed on a population of healthy subjects through innovative sensing devices which enable fast yet accurate evaluations of the above parameters. A statistical analysis was carried out to determine significant differences between the facial areas investigated and clusters of statistically-indistinguishable areas. We found that water content was higher in the cheeks and neck and lower in the lips, whereas trans-epidermal water loss had higher values for the lips and lower ones for the neck. In terms of thickness the dermis exhibited three clusters, which, from thickest to thinnest were: chin and nose, cheek and forehead and lips and neck. The epidermis showed the same three clusters too, but with a different ordering in term of thickness. Finally, the stratum corneum presented two clusters: the thickest, formed by lips and neck, and the thinnest, formed by all the remaining areas. The results of this investigation can provide valuable guidelines for the evaluation of skin moisturisers and other cosmetic products, and can help guide choices in re-constructive/cosmetic surgery. Full article
(This article belongs to the Section Applied Biosciences and Bioengineering)
Show Figures

Figure 1

Open AccessArticle
Performance of Full-Duplex Wireless Back-Haul Link under Rain Effects Using E-Band 73 GHz and 83 GHz in Tropical Area
Appl. Sci. 2020, 10(17), 6138; https://doi.org/10.3390/app10176138 - 03 Sep 2020
Viewed by 240
Abstract
This paper presents rain attenuation effects on the performance of the full-duplex link in a tropical region based on one-year measurement data at 73.5- and 83.5-GHz E-band for distances of 1.8 km (longer links) and 300 m (shorter links). The measured rain attenuations [...] Read more.
This paper presents rain attenuation effects on the performance of the full-duplex link in a tropical region based on one-year measurement data at 73.5- and 83.5-GHz E-band for distances of 1.8 km (longer links) and 300 m (shorter links). The measured rain attenuations were analyzed for four links, and the throughput degradation due to rain was investigated. The findings from this work showed that the rain attenuation for both frequencies (73.5 and 83.5 GHz) of E-band links are the same. The rain rates above 108 and 193 mm/h caused an outage for the longer and shorter links, respectively. The 73.5 and 83.5 GHz bands can support the full-duplex wireless back-haul link under rainy conditions with outage probability of 2.9×104 and 6×105 for the longer and shorter links, respectively. This work also finds that the heavy rain with rain rates above 80 mm/h for long link and 110 mm/h for short link causes about 94% and 0.90% degradation of maximum throughput. The application of these findings would help improve the architecture and service of full-duplex wireless E-band links that are established at other sites and in other tropical areas. Full article
(This article belongs to the Section Electrical, Electronics and Communications Engineering)
Show Figures

Figure 1

Open AccessPerspective
Electrical Monitoring under Transient Conditions: A New Paradigm in Electric Motors Predictive Maintenance
Appl. Sci. 2020, 10(17), 6137; https://doi.org/10.3390/app10176137 - 03 Sep 2020
Viewed by 266
Abstract
Electric motors condition monitoring is a field of paramount importance for industry. In recent decades, there has been a continuous effort to investigate new techniques and methods that are able to determine the health of these machines with high accuracy and reliability. Classical [...] Read more.
Electric motors condition monitoring is a field of paramount importance for industry. In recent decades, there has been a continuous effort to investigate new techniques and methods that are able to determine the health of these machines with high accuracy and reliability. Classical methods based on the analysis of diverse machine quantities under stationary conditions are being replaced by modern methodologies that are adapted to any operation regime of the machine (including transients). These new methods (especially those based on motor startup signal monitoring), which imply the use of advanced signal processing tools, have shown great potential and have provided spectacular advantages versus conventional approaches enabling, among other facts, a much more reliable determination of the machine health. This paper reviews the background of this recent condition monitoring trend and shows the advantages of this new approach with regard to its application to the analysis of electrical quantities. Examples referred to its application to real motors operating in industry are included, proving the huge potential of the transient-based approach and its benefits versus conventional methods. Full article
Show Figures

Figure 1

Open AccessArticle
A Detailed One-Dimensional Hydrodynamic and Kinetic Model for Sorption Enhanced Gasification
Appl. Sci. 2020, 10(17), 6136; https://doi.org/10.3390/app10176136 - 03 Sep 2020
Viewed by 227
Abstract
Increased installation of renewable electricity generators requires different technologies to compensate for the associated fast and high load gradients. In this work, sorption enhanced gasification (SEG) in a dual fluidized bed gasification system is considered as a promising and flexible technology for the [...] Read more.
Increased installation of renewable electricity generators requires different technologies to compensate for the associated fast and high load gradients. In this work, sorption enhanced gasification (SEG) in a dual fluidized bed gasification system is considered as a promising and flexible technology for the tailored syngas production for use in chemical manufacturing or electricity generation. To study different operational strategies, as defined by gasification temperature or fuel input, a simulation model is developed. This model considers the hydrodynamics in a bubbling fluidized bed gasifier and the kinetics of gasification reactions and CO2 capture. The CO2 capture rate is defined by the number of carbonation/calcination cycles and the make-up of fresh limestone. A parametric study of the make-up flow rate (0.2, 6.6, and 15 kg/h) reveals its strong influence on the syngas composition, especially at low gasification temperatures (600–650 °C). Our results show good agreement with the experimental data of a 200 kW pilot plant, as demonstrated by deviations of syngas composition (5–34%), lower heating value (LHV) (5–7%), and M module (23–32%). Studying the fuel feeding rate (22–40 kg/h), an operational range with a good mixing of solids in the fluidized bed is identified. The achieved results are summarized in a reactor performance diagram, which gives the syngas power depending on the gasification temperature and the fuel feeding rate. Full article
Show Figures

Figure 1

Open AccessFeature PaperArticle
Nano-HPLC-HRMS Analysis to Evaluate Leptin Level in Milk Samples: A Pilot Study
Appl. Sci. 2020, 10(17), 6135; https://doi.org/10.3390/app10176135 - 03 Sep 2020
Viewed by 214
Abstract
Leptin is a 16 kDa lipophilic protein hormone secreted by adipocytes and its most significant function is to inform the brain with negative feedback that regulates food intake. Recently the protein found in human breast milk was related to breast feeding and onset [...] Read more.
Leptin is a 16 kDa lipophilic protein hormone secreted by adipocytes and its most significant function is to inform the brain with negative feedback that regulates food intake. Recently the protein found in human breast milk was related to breast feeding and onset of obesity, and the evidence of a low probability to develop pediatric obesity in children fed with breast milk was also confirmed. Since leptin could have a critical role, its quantitation both in human breast, bovine milk and in infant formula products is interesting. For this reason, we developed an analytical method based on immunoaffinity purification followed by an analysis with nano-High Pressure Liquid Chromatography coupled with High Resolution Mass Spectrometry analyzer (nano-HPLC-HRMS) to identify and quantify leptin in milk samples and performed a pilot study using samples of human breast milk, bovine milk and infant formulas. With an obtained lower limit of quantitation (LLOQ) of 100 ng mL−1 we quantified leptin in human breast milk finding an average of 6.70 ng mL−1. Our results show that leptin was under LLOQ both in bovine milk and in infant formula products. In conclusion, the developed analytical method here described was suitable to quantify leptin in milk samples with a good sensitivity and selectivity, and without the use of radioactive reagents. Full article
(This article belongs to the Special Issue Analysis of Chemical Biomarkers and Contaminants in Food)
Show Figures

Figure 1

Open AccessArticle
Testing and Fatigue Life Assessment of Timber Truck Stanchions
Appl. Sci. 2020, 10(17), 6134; https://doi.org/10.3390/app10176134 - 03 Sep 2020
Viewed by 237
Abstract
Components of transport trucks are subjected to dynamic cyclic loads. The magnitude of these loads depends on road conditions and cargo mass. Cyclic loads can cause fatigue failure at stress levels significantly below the yield strength of the material. When calculating fatigue, it [...] Read more.
Components of transport trucks are subjected to dynamic cyclic loads. The magnitude of these loads depends on road conditions and cargo mass. Cyclic loads can cause fatigue failure at stress levels significantly below the yield strength of the material. When calculating fatigue, it is necessary to determine the actual loads acting on the structure under working conditions. In this study, stanchion displacements of overloaded timber trucks were measured under both static and dynamic loads. For the specified mass of timber, a history of dynamic loads acting on the stanchion was obtained. Then, based on the finite element analysis, stress concentration points were determined within the base material and welded joints of the stanchion. The history of maximum stresses at concentration points was determined. Stress ranges and mean stresses for the load history were calculated using the rainflow fatigue cycle counting method. Repeats to failure were determined on the basis of the Palmgren–Miner cumulative damage rule and the modified Goodman correction for the points with the highest stress level. Experimental investigation of the actual load history of the stanchion of significantly overloaded timber truck allowed to determine the mileage to potential failure. Full article
(This article belongs to the Section Mechanical Engineering)
Show Figures

Figure 1

Open AccessArticle
Concept for Improved Handling Ensures Effective Contactless Plasma Treatment of Patients with kINPen® MED
Appl. Sci. 2020, 10(17), 6133; https://doi.org/10.3390/app10176133 - 03 Sep 2020
Viewed by 220
Abstract
The nursing of patients with wounds is an essential part of medical healthcare. In this context, cold atmospheric-pressure plasma sources can be applied for skin decontamination and stimulation of wound healing. One of these plasma devices is the commercially available kINPen® MED [...] Read more.
The nursing of patients with wounds is an essential part of medical healthcare. In this context, cold atmospheric-pressure plasma sources can be applied for skin decontamination and stimulation of wound healing. One of these plasma devices is the commercially available kINPen® MED (neoplas tools GmbH), a cold atmospheric-pressure plasma jet which is approved as a medical device, class-IIa. For the plasma treatment, a sterile disposable spacer is recommended to ensure a constant and effective distance between plasma and skin. The disadvantage of this spacer is its form and size which means that the effective axis/area is not visible for the attending doctor or qualified personnel and consequently it is a more or less intuitive treatment. In addition, the suggested perpendicular treatment is not applicable for the attending specialist due to lack of space or patient/wound positioning. A concept of a sensory unit was developed to measure the treatment distance and to visualize the effective treatment area for different angles. To determine the effective area for the plasma treatment, some exemplary methods were performed. Thus, the antimicrobial (Staphylococcus aureus DSM799/ATCC6538) efficacy, reactive oxygen species (ROS) distribution and (vacuum) ultraviolet ((V)UV) irradiation were determined depending on the treatment angle. Finally, a simplified first approach to visualize the effective treatment area at an optimal distance was designed and constructed to train attending specialists for optimal wound area coverage. Full article
Show Figures

Figure 1

Open AccessFeature PaperArticle
Visualizations of Uncertainties in Precision Agriculture: Lessons Learned from Farm Machinery
Appl. Sci. 2020, 10(17), 6132; https://doi.org/10.3390/app10176132 - 03 Sep 2020
Viewed by 308
Abstract
Detailed measurements of yield values are becoming a common practice in precision agriculture. Field harvesters generate point Big Data as they provide yield measurements together with dozens of complex attributes in a frequency of up to one second. Such a flood of data [...] Read more.
Detailed measurements of yield values are becoming a common practice in precision agriculture. Field harvesters generate point Big Data as they provide yield measurements together with dozens of complex attributes in a frequency of up to one second. Such a flood of data brings uncertainties caused by several factors: accuracy of the positioning system used, trajectory overlaps, raising the cutting bar due to obstacles or unevenness, and so on. This paper deals with 2D and 3D cartographic visualizations of terrain, measured yield, and its uncertainties. Four graphic variables were identified as credible for visualizations of uncertainties in point Big Data. Data from two plots at a fully operational farm were used for this purpose. ISO 19157 was examined for its applicability and a proof-of-concept for selected uncertainty expression was defined. Special attention was paid to spatial pattern interpretations. Full article
(This article belongs to the Special Issue Visualisation of Big Data in Agriculture)
Show Figures

Graphical abstract

Open AccessArticle
Effects of Greenshell Mussel (Perna canaliculus) Intake on Pathological Markers of Multiple Phenotypes of Osteoarthritis in Rats
Appl. Sci. 2020, 10(17), 6131; https://doi.org/10.3390/app10176131 - 03 Sep 2020
Viewed by 215
Abstract
The prevalence of metabolic osteoarthritis has been increasing worldwide, particularly among women. The aim of this study was to investigate the effects of the New Zealand greenshell mussel (Perna canaliculus; GSM) on osteoarthritis (OA) prevention in a rat model. One-hundred-and-eight female [...] Read more.
The prevalence of metabolic osteoarthritis has been increasing worldwide, particularly among women. The aim of this study was to investigate the effects of the New Zealand greenshell mussel (Perna canaliculus; GSM) on osteoarthritis (OA) prevention in a rat model. One-hundred-and-eight female rats aged 12 weeks were divided into four test groups, containing 24 rats each, plus an additional control group. Each test group received one of the four experimental diets: normal control diet (ND), normal control diet supplemented with GSM (ND + GSM), high fat/high sugar diet (HFHS), or high fat/high sugar diet supplemented GSM (HFHS + GSM), for 36 weeks (end of the study). After 8 weeks on experimental diets, half of each group was subjected to ovariectomy (OVX) and the remaining half received a sham operation (ovaries left intact). The study evaluated body composition, bone mass, plasma cytokines, adipokines, HbA1c, CTX-II, and knee joint’s histopathology. HFHS diet and OVX significantly induced body weight gain and leptin production. OVX rats lost bone mineral density but increased adiponectin, HbA1C, and MCP-1. The OVX rats fed HFHS showed the highest Mankin scores. Importantly, inclusion of GSM reduced these pathological features. In conclusion, GSM might be beneficial in halting the progression of OA. Full article
(This article belongs to the Special Issue Biomechanical and Biomedical Factors of Knee Osteoarthritis)
Show Figures

Figure 1

Open AccessFeature PaperArticle
Small-Signal Analysis and Control of Soft-Switching Naturally Clamped Snubberless Current-Fed Half-Bridge DC/DC Converter
Appl. Sci. 2020, 10(17), 6130; https://doi.org/10.3390/app10176130 - 03 Sep 2020
Viewed by 203
Abstract
This paper presents small-signal analysis of a soft-switching naturally clamped snubberless isolated current-fed half-bridge (CFHB) DC-DC converter using state-space averaging. A two-loop average current controller was designed and implemented on a digital signal processor. The complete design procedure is presented here. Simulation results [...] Read more.
This paper presents small-signal analysis of a soft-switching naturally clamped snubberless isolated current-fed half-bridge (CFHB) DC-DC converter using state-space averaging. A two-loop average current controller was designed and implemented on a digital signal processor. The complete design procedure is presented here. Simulation results using software PSIM 11.1 are shown to validate the stability of the control system and the controller design. Experimental results for the step changes in load current vividly demonstrated satisfactory transient performance of the converter and validated the developed small-signal model and the control design. Full article
Show Figures

Figure 1

Open AccessArticle
Analysis of Crack Behaviour in Pipeline System Using FAD Diagram Based on Numerical Simulation under XFEM
Appl. Sci. 2020, 10(17), 6129; https://doi.org/10.3390/app10176129 - 03 Sep 2020
Viewed by 232
Abstract
For a long time, cracked structures have triggered various researchers to develop a structural integrity approach and design models to address the fracture problems. In the present study, a pipeline with an axial semi-elliptical surface defect was examined in detail. Recent works have [...] Read more.
For a long time, cracked structures have triggered various researchers to develop a structural integrity approach and design models to address the fracture problems. In the present study, a pipeline with an axial semi-elliptical surface defect was examined in detail. Recent works have highlighted the use of the classical finite element method (CFEM) as numerical tools to solve the fracture mechanics; however, this approach comes with a few difficulties in the modelling aspects. To overcome this issue, we proposed the use of the extended finite element method (XFEM), which was implemented in the commercial version of Abaqus software. Moreover, we have used the results based on this technique in the volumetric method to estimate the stress intensity factors (SIFs). Then, this parameter was employed to build the failure assessment diagram (FAD). The FAD curve was used in the current investigation because it is one of the conventional methods for the evaluation of flaws in steel pipes. The XFEM simulations enable us to draw an FAD curve that can be used as a practical reference for defect evaluation in pipeline systems in the industrial world. Full article
(This article belongs to the Special Issue Fracture and Fatigue Assessments of Structural Components Ⅱ)
Open AccessArticle
Coupled-Cavity VCSEL with an Integrated Electro-Absorption Modulator: Small- and Large-Signal Modulation Analysis
Appl. Sci. 2020, 10(17), 6128; https://doi.org/10.3390/app10176128 - 03 Sep 2020
Viewed by 206
Abstract
We consider an integrated electro-absorption modulator within a coupled-cavity VCSEL structure (EAM-VCSEL). We derive expressions for the modulation transfer function (MTF) of the EAM-VCSEL for small-signal modulation of either VCSEL injection current or EAM losses. For current modulation, the cut-off frequency remains limited [...] Read more.
We consider an integrated electro-absorption modulator within a coupled-cavity VCSEL structure (EAM-VCSEL). We derive expressions for the modulation transfer function (MTF) of the EAM-VCSEL for small-signal modulation of either VCSEL injection current or EAM losses. For current modulation, the cut-off frequency remains limited by relaxation oscillation frequency. For EAM loss modulation, the MTF curve is much flatter and its shape around the relaxation oscillation frequency displays either a well-pronounced maximum, both a maximum and a minimum or a sharp minimum only depending on the bias point of the EAM losses. Such features have been found experimentally in Marigo-Lombart et al., J. Physiscs: Photonics, 1, 2019, but remained unexplained hitherto. Furthermore, the cut-off frequency remains beyond 100 GHz for moderate and week coupling between the VCSEL and EAM cavities. Such ultrahigh bandwidth modulation is due to the fact that the changes of EAM impact much less the optical power distribution along the EAM-VCSEL and, consequently, the confinement factor and photon density in the VCSEL cavity. The three cases of strong, intermediate and weak coupling are also considered when carrying out the large-signal modulation response of the EAM-VCSEL and a clear open-eye diagram is demonstrated at 100 Gbs for an optimal EAM cavity length. Full article
(This article belongs to the Section Optics and Lasers)
Show Figures

Figure 1

Open AccessArticle
Effect of Equivalent Load Distribution on the Accuracy of Mapping the Reinforcement Load Deflection Curve in LTP
Appl. Sci. 2020, 10(17), 6127; https://doi.org/10.3390/app10176127 - 03 Sep 2020
Viewed by 203
Abstract
The formulations of tasks modelling embankments on soft soil, improved with columns and with reinforced load transfer platform (LTP), differ significantly. One of these differences is the distribution of equivalent load modelling part of the load carried by the LTP reinforcement and soft [...] Read more.
The formulations of tasks modelling embankments on soft soil, improved with columns and with reinforced load transfer platform (LTP), differ significantly. One of these differences is the distribution of equivalent load modelling part of the load carried by the LTP reinforcement and soft soil. This article analyses the influence of the nature of the load-modelling linear function, i.e., inverse triangular, uniformly distributed and triangular, as well as intermediate distributions. In total, 41 distributions of equivalent load were considered, and the results of the obtained deflection functions were compared with the measurement results of reinforcement deflection for 5 cases of experimental research available in the literature. A measure of the accuracy of mapping the reinforcement deflection curve was proposed as a relative error in relation to the deflection curve resulting from experimental measurements. Based on the analysis of the mapping error, it was determined that among the three commonly used distributions, the inverse triangular distribution shows the best fit in most of the analysed cases. However, not in every single case this is the distribution leading to a solution that best describes the behaviour of the geosynthetic reinforcement. Full article
(This article belongs to the Section Civil Engineering)
Show Figures

Figure 1

Open AccessArticle
Body Scan Processing, Generative Design, and Multiobjective Evaluation of Sports Bras
Appl. Sci. 2020, 10(17), 6126; https://doi.org/10.3390/app10176126 - 03 Sep 2020
Viewed by 202
Abstract
Sports bras are critical to the comfort and performance of female athletes, yet mechanical models of sports bras are generally not used to guide their design. Typically, assessing any sports bra’s performance requires time-consuming and expensive biomechanical testing, which limits the number of [...] Read more.
Sports bras are critical to the comfort and performance of female athletes, yet mechanical models of sports bras are generally not used to guide their design. Typically, assessing any sports bra’s performance requires time-consuming and expensive biomechanical testing, which limits the number of designs considered. To more broadly advance knowledge on how different design properties of sports bras affect their performance, this paper presents a new design framework to explore and evaluate the sports bra design space. The framework incorporates methods for body scan analysis, fast simulation, design generation, and performance evaluation. Using these methods together enables the rapid exploration of hundreds, or thousands, of designs—each one having been evaluated on key metrics related to sports bra performance, namely, range of motion and average pressure. With this framework, designers can potentially discover a diverse set of new, high-performing sports bra concepts, as well as gain insights into how design decisions affect performance. Full article
(This article belongs to the Special Issue Design, Manufacture and Analysis of Sports Equipment)
Show Figures

Graphical abstract

Open AccessArticle
Requirements Engineering in Software Startups: A Systematic Mapping Study
Appl. Sci. 2020, 10(17), 6125; https://doi.org/10.3390/app10176125 - 03 Sep 2020
Viewed by 291
Abstract
Startups have high failure rates due to their inability to attain a sufficient product/market fit, i.e., delivering a solution that best matches the user needs in the market. Requirement engineering is the activity that could help startup teams identify the value proposition that [...] Read more.
Startups have high failure rates due to their inability to attain a sufficient product/market fit, i.e., delivering a solution that best matches the user needs in the market. Requirement engineering is the activity that could help startup teams identify the value proposition that provides high value to the users and continuously innovate it. The objective of the study is to analyse the state of art of the requirement engineering research in the context of startups, as available in the literature. The analysis of the research area highlights the research trends to achieve two things i.e., (a) predict how much support the startups can get from the literature for enhancing their success rates and (b) identify the research gaps to motivate researchers to conduct future research that could be adoptable in startup contexts. Systematic mapping is conducted on studies extracted from the four bibliographic databases (IEEExplore, ACM, Springerlink and ScienceDirect) and studies extracted by using a forward snowballing approach. Individual studies are coded to yield the classification scheme. Formulated schemes and those already available in literature, were populated with information extracted from the abstracts of the studies. The research is mostly focused on generic requirement engineering and product validation activities. The research is conducted mostly as evaluations (empirical studies) with the outcome of providing theory to the research community. Major underlying motivation of the research is to attain the product/market fit. However, research studies focusing on requirement documentation, prioritization and elicitation are losing focus from 2017, 2018 and 2019, respectively. The literature lacks the studies that reports research solutions which are validated in laboratory settings or in real contexts, experience reports, opinion papers and philosophical papers. The positive side of the finding is that the number of requirement engineering research studies in a startup context have increased in the past five years. At this instant, unfortunately the literature has limited ability to support startups by providing solutions (for instance, research solutions, evidence to support decision makings, best practices, experiences etc.) that are adoptable in their real context. Uniform focus of the researchers across all sub-activities of requirement engineering is required with effort distributed across different research types that supports startups, not only by providing validated solutions but experience reports, opinions, new conceptual frameworks and empirical evidence that can aid their decision making. Full article
Show Figures

Graphical abstract

Open AccessFeature PaperArticle
A Personalised Emotion-Based Model for Relaxation in Virtual Reality
Appl. Sci. 2020, 10(17), 6124; https://doi.org/10.3390/app10176124 - 03 Sep 2020
Viewed by 219
Abstract
One of the most frequent health problems is stress. It has been linked to negative effects on employee well-being in many occupations, and it is considered responsible for many physical and psychological problems. Traditional in-person relaxation therapy has proven to be effective in [...] Read more.
One of the most frequent health problems is stress. It has been linked to negative effects on employee well-being in many occupations, and it is considered responsible for many physical and psychological problems. Traditional in-person relaxation therapy has proven to be effective in reducing stress. However, it has some drawbacks such as high cost, required infrastructure and the need for qualified trainers. Relaxation therapy in Virtual Reality (VR) tries to solve these problems. However, one aspect has received little attention, that is personalised therapy. Indeed, while many studies show the need for patient-tailored relaxation exercises, little existing work focuses on personalised VR content. One reason for this is the complexity of recognising emotions, which is required for emotion-based adaptive VR. In this work, a method for adapting VR content to the emotional state of the user is presented. This model has been applied in a VR relaxation therapy application, which adapts to the user’s emotional state utilising a heuristic optimiser. Simulations have proven the performance and usability of the emotion model. Additionally, this paper explores the impact of the order in which adaptations are performed on the effectiveness of the relaxation experience. Full article
(This article belongs to the Special Issue Innovative Solutions for Augmented and Virtual Reality Applications)
Open AccessArticle
Analysis of Defects in Residential Buildings Reported during the Warranty Period
Appl. Sci. 2020, 10(17), 6123; https://doi.org/10.3390/app10176123 - 03 Sep 2020
Viewed by 202
Abstract
The aim of the article is to present the results of preliminary research of the defects in residential buildings occurring during the warranty period. Due to the small amount of data, the research results cannot be generalized but allow for the formulation of [...] Read more.
The aim of the article is to present the results of preliminary research of the defects in residential buildings occurring during the warranty period. Due to the small amount of data, the research results cannot be generalized but allow for the formulation of research hypotheses that will be verified in future studies. The data collected included reports of defects in three multifamily residential buildings constructed by the developer in one of the big cities in Poland, which were then examined. For the examination of defects, statistical analysis was used, which revealed that more than half of the reports contained reasonable defects. The results of the preliminary research also indicate that, on the one hand, owners are very active in making warranty claims in the first three months from the date of commissioning, and, on the other hand, with time, the percentage of reasonable defects increases. In terms of the significance of defects, the largest percentage was significant defects. The results showed little activity on the part of property managers in the initial phase of the operation of the buildings, which is the opposite of that of apartment owners. Reports of faults in windows and door joinery, moisture, scratches on walls, and in the area of balconies and terraces are characterized by a relatively low number of cases reported in the first half of the year after the building is commissioned and a gradual increase in the subsequent warranty period. On the other hand, reports related to electrical installation defects are most frequent in the initial period of the warranty, but, with time, their number decreases. Full article
Show Figures

Figure 1

Open AccessReview
On the Statistical Characterization of Sprays
Appl. Sci. 2020, 10(17), 6122; https://doi.org/10.3390/app10176122 - 03 Sep 2020
Viewed by 237
Abstract
The statistical characterization of sprays is an essential way of organizing data on drop size and velocity to provide reliable information on the spray dynamics. A clear presentation of data using statistical tools provides evidence of a clear research question underlying the spray [...] Read more.
The statistical characterization of sprays is an essential way of organizing data on drop size and velocity to provide reliable information on the spray dynamics. A clear presentation of data using statistical tools provides evidence of a clear research question underlying the spray characterization. In this article, a review of the best practices to build histograms is presented, as well as three relevant details on spray characterization: (i) the application of information theory to assess if we have enough information (not data); (ii) the link between mathematical probability distributions and the physical interpretation of spray data; (iii) and introducing, for the first time, the concept of drop size diversity, with the quantification of the polydispersion and heterogeneity degrees. Finally, the view presented is applied to the characterization of nanofluid sprays for thermal management. Full article
(This article belongs to the Special Issue Progress in Spray Science and Technology)
Show Figures

Figure 1

Open AccessArticle
Predictive Scheduling with Markov Chains and ARIMA Models
Appl. Sci. 2020, 10(17), 6121; https://doi.org/10.3390/app10176121 - 03 Sep 2020
Viewed by 205
Abstract
Production scheduling is attracting considerable scientific interest. Effective scheduling of production jobs is a critical element of smooth organization of the work in an enterprise and, therefore, a key issue in production. The investigations focus on improving job scheduling effectiveness and methodology. Due [...] Read more.
Production scheduling is attracting considerable scientific interest. Effective scheduling of production jobs is a critical element of smooth organization of the work in an enterprise and, therefore, a key issue in production. The investigations focus on improving job scheduling effectiveness and methodology. Due to simplifying assumptions, most of the current solutions are not fit for industrial applications. Disruptions are inherent elements of the production process and yet, for reasons of simplicity, they tend to be rarely considered in the current scheduling models. This work presents the framework of a predictive job scheduling technique for application in the job-shop environment under the machine failure constraint. The prediction methods implemented in our work examine the nature of the machine failure uncertainty factor. The first section of this paper presents robust scheduling of production processes and reviews current solutions in the field of technological machine failure analysis. Next, elements of the Markov processes theory and ARIMA (auto-regressive integrated moving average) models are introduced to describe the parameters of machine failures. The effectiveness of our solutions is verified against real production data. The data derived from the strategic machine failure prediction model, employed at the preliminary stage, serve to develop the robust schedules using selected dispatching rules. The key stage of the verification process concerns the simulation testing that allows us to assess the execution of the production schedules obtained from the proposed model. Full article
(This article belongs to the Special Issue Design and Management of Manufacturing Systems)
Show Figures

Figure 1

Open AccessArticle
A Novel Cooperative Controller for Inverters of Smart Hybrid AC/DC Microgrids
Appl. Sci. 2020, 10(17), 6120; https://doi.org/10.3390/app10176120 - 03 Sep 2020
Viewed by 210
Abstract
This paper presents a novel cooperative control technique concerning fully-distributed AC/DC microgrids. Distributed generation based on inverters has two types, i.e., Current Source Inverter (CSI), also referred to as PQ inverter, and Voltage Source Inverter (VSI). Both inverter forms have a two-layer coordination [...] Read more.
This paper presents a novel cooperative control technique concerning fully-distributed AC/DC microgrids. Distributed generation based on inverters has two types, i.e., Current Source Inverter (CSI), also referred to as PQ inverter, and Voltage Source Inverter (VSI). Both inverter forms have a two-layer coordination mechanism. This paper proposes a design method for the digital Proportional-Resonant (PR) controller that regulates the current inside an inverter. The inverters will improve the voltage quality of the microgrid while maintaining the average voltage of buses at the same desired level. There is comprehensive detail on the computations specific to resonant and proportional gains and digital resonance path coefficients. The paper includes a digital PR controller design and its analysis in the frequency domain. The analysis is based on the w-domain. The main contribution of this paper is the proposed method, which not only focuses on the transient response but also improves the steady-state response which smoothens the voltage; furthermore, all inverters are effectively involved to increase the capacity of the microgrid for better power management. The suggested cooperative control technique is used on an IEEE 14-bus system having fully distributed communication. The convincing outcomes indicate that the suggested control technique is an effectual means of regulating the microgrid’s voltage to obtain an evener and steady voltage profile. The microgrid comprises distributed resources and is used as the primary element to analyse power flow and quality indicators associated with a smart grid. Lastly, numerical simulation observations are utilised for substantiating the recommended algorithm. Full article
Show Figures

Figure 1

Open AccessArticle
Design and Performance Analysis for the Low-Power Holding Mechanism of the All-Electric Subsea Gate Valve Actuator
Appl. Sci. 2020, 10(17), 6119; https://doi.org/10.3390/app10176119 - 03 Sep 2020
Viewed by 196
Abstract
The all-electric subsea gate valve actuator is one of the critical components of the all-electric subsea production control system. To bridge the gap of the low-power holding mechanism in the all-electric subsea gate valve actuator of the subsea production system, minimize the power [...] Read more.
The all-electric subsea gate valve actuator is one of the critical components of the all-electric subsea production control system. To bridge the gap of the low-power holding mechanism in the all-electric subsea gate valve actuator of the subsea production system, minimize the power consumption and cable number for control and improve the open-position keeping performance of all-electric subsea gate valve actuator, this paper proposed a novel low-power holding mechanism for the all-electric subsea gate valve actuator which can be applied to all-electric subsea gate valve actuators with various valve sizes and process pressure ratings. The proposed low-power holding mechanism uses an electromagnet as a driving element, combines the spiral transmission and the cam-like transmission, and only requires a holding force of approximately 2–7% of the maximum load of the closing spring to keep the valve open. The proposed low-power holding mechanism converts the axial force of the closing spring into the circumferential force, which substantially reduces the output force required for the driving element of the low-power holding mechanism and the number of the actuator’s control cables. Analytic models are created for the lockable maximum load of the closing spring and the permissible stroke of the locking tab with regard to the design variables. The parameter effects and the corresponding sensitivities are discussed by numerical analysis. The design parameters and the lockable maximum load of the closing spring of the low-power holding mechanism are obtained. Full article
(This article belongs to the Section Mechanical Engineering)
Show Figures

Figure 1

Open AccessArticle
Rectangular Closed Double Magnetic Circuit Offering Ultra-Long Stroke for Ultra-Low-Frequency Vibration Exciter
Appl. Sci. 2020, 10(17), 6118; https://doi.org/10.3390/app10176118 - 03 Sep 2020
Viewed by 198
Abstract
High-performance magnetic circuit offering uniform magnetic flux density (MFD) along ultra-long stroke is the key to develop a vibration exciter for ultra-low-frequency (ULF) vibration calibration. In this paper, a rectangular closed double magnetic circuit (RCDMC) offering ultra-long stroke up to 1.2 m is [...] Read more.
High-performance magnetic circuit offering uniform magnetic flux density (MFD) along ultra-long stroke is the key to develop a vibration exciter for ultra-low-frequency (ULF) vibration calibration. In this paper, a rectangular closed double magnetic circuit (RCDMC) offering ultra-long stroke up to 1.2 m is modeled and optimized. In order to overcome the modeling difficulty arising from the long stroke, a high-accuracy theoretical model is established taking advantage of the structural symmetry of the RCDMC through lumped parameter magnetic equivalent circuit method. Matrix equations are derived based on Kirchhoff’s law and solved by iteration calculation to deal with the strong nonlinear characteristics of the yoke material. The deviations between the model and finite element method (FEM) analysis results are less than 1% for non-saturated yokes and ~10% for saturated yokes. Theoretically, an MFD up to 122 mT and an acceleration waveform harmonic distortion (AWHD) as low as 0.45% are achieved through model-based optimization. Experiments are carried out using an RCDMC prototype assembled in a horizontal vibration exciter. The experimental results show that an MFD of 102 mT and an AWHD of 0.27% along 1.2 m stroke are achieved, making the proposed RCDMC a solution for ULF vibration exciter. Full article
(This article belongs to the Section Applied Physics)
Show Figures

Figure 1

Open AccessFeature PaperArticle
Regional Variation and Socio-Economic Determinants of Suicide Mortality in Greece before and during Economic Crisis
Appl. Sci. 2020, 10(17), 6117; https://doi.org/10.3390/app10176117 - 03 Sep 2020
Viewed by 192
Abstract
Background. Suicide mortality increased in Greece after the 2008 financial crisis. This study aimed to explore the regional variation of suicide mortality before and after the economic crisis, and its correlation with socio-economic and mental health-related variables factors. Methods. This is a quasi-experimental [...] Read more.
Background. Suicide mortality increased in Greece after the 2008 financial crisis. This study aimed to explore the regional variation of suicide mortality before and after the economic crisis, and its correlation with socio-economic and mental health-related variables factors. Methods. This is a quasi-experimental ecological study. Data from the national mortality statistics were analyzed, and standardized death rates and age-specific mortality rates were calculated. The effect of economic crisis was explored by comparing mortality rates before and after crisis onset. Pearson’s and Spearman’s correlation coefficients and multiple linear regression were used to assess the impact of socioeconomic and mental health-related factors on suicide mortality. Results. Trends of suicide mortality showed a rise during 2011–2014, followed by a decline during 2015–2016. Significant differences were observed between regions, ranging from 27.6% lower to 54% higher than the national average. Unemployment, income, and change of gross domestic product were significantly correlated with regional variation. No association was found with mental disorder mortality rates and psychotropic drug consumption. Conclusions. Socio-economic factors explained only a part of the suicide mortality variation. Mental health-related factors were not significantly correlated with suicide mortality. More research is needed to investigate other possible determinants of suicides. Full article
(This article belongs to the Special Issue Epidemiology and Public Health 2020)
Show Figures

Figure 1

Open AccessArticle
Lightweight Detection Method of Obfuscated Landing Sites Based on the AST Structure and Tokens
Appl. Sci. 2020, 10(17), 6116; https://doi.org/10.3390/app10176116 - 03 Sep 2020
Viewed by 219
Abstract
Attackers use a variety of techniques to insert redirection JavaScript that leads a user to a malicious webpage, where a drive-by-download attack is executed. In particular, the redirection JavaScript in the landing site is obfuscated to avoid detection systems. In this paper, we [...] Read more.
Attackers use a variety of techniques to insert redirection JavaScript that leads a user to a malicious webpage, where a drive-by-download attack is executed. In particular, the redirection JavaScript in the landing site is obfuscated to avoid detection systems. In this paper, we propose a lightweight detection system based on static analysis to classify the obfuscation type and to promptly detect the obfuscated redirection JavaScript. The proposed model detects the obfuscated redirection JavaScript by converting the JavaScript into an abstract syntax tree (AST). Then, the structure and token information are extracted. Specifically, we propose a lightweight AST to identify the obfuscation type and the revised term frequency-inverse document frequency to efficiently detect the malicious redirection JavaScript. This approach enables rapid identification of the obfuscated redirection JavaScript and proactive blocking of the webpages that are used in drive-by-download attacks. Full article
Show Figures

Figure 1

Open AccessArticle
Overtaking Collisions of Ion Acoustic N-Shocks in a Collisionless Plasma with Pair-Ion and (α,q) Distribution Function for Electrons
Appl. Sci. 2020, 10(17), 6115; https://doi.org/10.3390/app10176115 - 03 Sep 2020
Viewed by 203
Abstract
In this work, the effects of plasma parameters on overtaking collisions of ion acoustic multi-shocks are studied in an unmagnetized collisionless plasma with positive and negative ions, and (α,q)-distributed electrons. To investigate such phenomena, the reductive perturbation technique is [...] Read more.
In this work, the effects of plasma parameters on overtaking collisions of ion acoustic multi-shocks are studied in an unmagnetized collisionless plasma with positive and negative ions, and (α,q)-distributed electrons. To investigate such phenomena, the reductive perturbation technique is implemented to derive the Burgers equation. The N-shock wave solution is determined for this equation by directly implementing the exponential function. The result reveals that both the amplitudes and thicknesses of overtaking collisions of N-shock wave compressive and rarefactive electrostatic potential are significantly modified with the influences of viscosity coefficients of positive and negative ions. In addition, the density ratios also play an essential role to the formation of overtaking collisions of N-shocks. It is observed from all theoretical and parametric investigations that the outcomes may be very useful in understanding the dynamical behavior of overtaking collisions of multi-shocks in various environments, especially the D- and F-regions of the Earth’s ionosphere and the future experimental investigations in Q-machine laboratory plasmas. Full article
(This article belongs to the Section Applied Physics)
Show Figures

Figure 1

Previous Issue
Back to TopTop