Applied Sciences

14 pages, 5888 KiB

Open AccessArticle

Modeling, Simulation, and Cruise Characteristics of Wingtip-Jointed Composite Aircraft

by Dongxu Liu, Changchuan Xie, Guanxin Hong and Chao An

Appl. Sci. 2020, 10(23), 8763; https://doi.org/10.3390/app10238763 - 7 Dec 2020

Cited by 2 | Viewed by 2619

In this paper, multibody dynamic modeling and a simulation method for the wingtip-jointing process of a new-concept composite aircraft system are investigated. When the wingtips of two aircraft are jointed, the resultant wingtip-jointed aircraft is regarded as variable-geometry multiple rigid bodies, and a [...] Read more.

In this paper, multibody dynamic modeling and a simulation method for the wingtip-jointing process of a new-concept composite aircraft system are investigated. When the wingtips of two aircraft are jointed, the resultant wingtip-jointed aircraft is regarded as variable-geometry multiple rigid bodies, and a seven-degree-of-freedom non-linear dynamic model is established by mathematical derivation. The slip-meshing method is adopted to analyze the unsteady aerodynamic influence. We also present specific aerodynamic database acquisition methods under the quasi-steady assumption. Based on this, the simulation results indicate that the longitudinal and lateral movements are highly jointed and complex. A new composite aircraft system is investigated, in order to meet the balance requirement. With the lift–drag ratio (K) considered, the piecewise cubic Hermite interpolation (PCHIP) method, with a sufficient sample size, was utilized to help the cruise strategy optimization analysis under fixed altitude and speed conditions. Meanwhile, distribution of cruise characteristics with different sampling values of composite flight characteristic parameters were also analyzed. The research results can be used as a reference for new-concept composite aircraft model establishment, simulation, and multibody dynamic characteristic investigation. Full article

(This article belongs to the Section Aerospace Science and Engineering)

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16 pages, 522 KiB

Open AccessArticle

A Relay Selection Protocol for UAV-Assisted VANETs

by Yixin He, Daosen Zhai, Dawei Wang, Xiao Tang and Ruonan Zhang

Appl. Sci. 2020, 10(23), 8762; https://doi.org/10.3390/app10238762 - 7 Dec 2020

Cited by 29 | Viewed by 3373

Abstract

In this paper, we investigate the relay selection problem for the unmanned aerial vehicle (UAV)-assisted vehicular ad-hoc networks (VANETs). For the considered network, we first model and analyze the link quality of service (LQoS) from the source node (SN) to the neighbor node [...] Read more.

In this paper, we investigate the relay selection problem for the unmanned aerial vehicle (UAV)-assisted vehicular ad-hoc networks (VANETs). For the considered network, we first model and analyze the link quality of service (LQoS) from the source node (SN) to the neighbor node and the node forward capacity (NFC) from the neighbor node to the destination node (DN). Then, the relay selection problem is formulated as a multi-objective optimization problem by jointly considering the LQoS and the NFC. Afterward, we decompose the problem into two subproblems and propose a relay selection protocol with the storage-carry-forward (SCF) method. Moreover, we define a utility function with the node encounter frequency (NEF) and the message time-to-live (TTL) taken into account, based on which a redundant copy-deleting approach is devised. Furthermore, we analyze the security of the designed protocol. Finally, the simulation results demonstrate that the proposed relay selection protocol can improve the message delivery ratio, reduce the average end-to-end delay, and limit the overhead. Full article

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14 pages, 9881 KiB

Open AccessArticle

Ultrasonic Fatigue Device and Behavior of High-Temperature Superalloy Inconel 718 with Self-Heating Phenomenon

by Mengxiong Zhao, Tieying Wu, Zhenhua Zhao, Lulu Liu, Gang Luo and Wei Chen

Appl. Sci. 2020, 10(23), 8761; https://doi.org/10.3390/app10238761 - 7 Dec 2020

Cited by 3 | Viewed by 3217

Abstract

Ultrasonic resonance fatigue test method at 20 kHz related to the very high cycle fatigue (VHCF) aims to accelerate a time-consuming experiment. In this paper, an ultrasonic fatigue device with a data acquisition system was improved for monitoring and recording the data from [...] Read more.

Ultrasonic resonance fatigue test method at 20 kHz related to the very high cycle fatigue (VHCF) aims to accelerate a time-consuming experiment. In this paper, an ultrasonic fatigue device with a data acquisition system was improved for monitoring and recording the data from fatigue tests in which self-heating phenomenon exists. Symmetric tension-compression sinusoidal vibrating mode (R = −1) was observed in this study. VHCF behavior and mechanism of Inconel 718 were carried out using this device. It was concluded that more than 99% of fatigue life is consumed in initiation duration. Specimen temperature increase was not a decisive factor in VHCF strength for Inconel 718, as long as it was far less than the design temperature limitation. A single initiation site existed at the subsurface facet or grain cluster, observed from scanning electron microscope (SEM) micrographs. Quasi-cleavage fracture in transgranular ductile mode emerged and then tended to trace grain boundaries in an intergranular manner by cleavage-dominated mixed mode. Full article

(This article belongs to the Special Issue Advances in Very-High-Cycle Fatigue)

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13 pages, 563 KiB

Open AccessArticle

Trajectory/Path-Following Controller Based on Nonlinear Jerk-Level Error Dynamics

by Patrick Piprek, Michael M. Marb, Pranav Bhardwaj and Florian Holzapfel

Appl. Sci. 2020, 10(23), 8760; https://doi.org/10.3390/app10238760 - 7 Dec 2020

Cited by 12 | Viewed by 4034

Abstract

This study proposes a novel, nonlinear trajectory/path-following controller based on jerk-level error dynamics. Therefore, at first the nonlinear acceleration-based kinematic equations of motion of a dynamic system are differentiated with respect to time to obtain a representation connecting the translation jerk with the [...] Read more.

This study proposes a novel, nonlinear trajectory/path-following controller based on jerk-level error dynamics. Therefore, at first the nonlinear acceleration-based kinematic equations of motion of a dynamic system are differentiated with respect to time to obtain a representation connecting the translation jerk with the (specific) force derivative. Furthermore, the path deviation, i.e., the difference between the planned and the actual path, is formulated as nonlinear error dynamics based on the jerk error. Combining the derived equations of motion with the nonlinear error dynamics as well as employing nonlinear dynamic inversion, a control law can be derived that provides force derivative commands, which may be commanded to an inner loop for trajectory control. This command ensures an increased smoothness and faster reaction time compared to traditional approaches based on a force directly. Furthermore, the nonlinear parts in the error dynamic are feedforward components that improve the general performance due to their physical connection with the real dynamics. The validity and performance of the proposed trajectory/path-following controller are shown in an aircraft-related application example. Full article

(This article belongs to the Special Issue Nonlinear Control: Theory and Applications)

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11 pages, 9308 KiB

Open AccessArticle

Development of a Natural Matrix Hybrid Hydrogel Patch and Evaluation of Its Efficacy against Atopic Dermatitis

by Gyeong Sik Hong, Jeong Yeon Choi, Jang Soo Suh, Jeong Ok Lim and Jin Hyun Choi

Appl. Sci. 2020, 10(23), 8759; https://doi.org/10.3390/app10238759 - 7 Dec 2020

Cited by 6 | Viewed by 3536

Abstract

Although there is no cure for atopic dermatitis (AD), treatments to relieve AD symptoms are available. A previously developed topical patch for AD treatment minimizes skin irritation but does not sufficiently adhere and absorb to specific areas. Centella asiatica extract (CAE) is a [...] Read more.

Although there is no cure for atopic dermatitis (AD), treatments to relieve AD symptoms are available. A previously developed topical patch for AD treatment minimizes skin irritation but does not sufficiently adhere and absorb to specific areas. Centella asiatica extract (CAE) is a natural polymer for atopic treatment. This study fabricated a CAE-loaded hyaluronic acid-dextran (HA-Dex) hybrid hydrogel patch for use as an AD treatment and evaluated the effect of varying CAE concentrations in the patch. The CAE-loaded HA-Dex hybrid hydrogel patch was fabricated into a sheet-type scaffold using a freeze-drying process and 1,4-butanediol diglycidyl ether (BDDE). Fibroblasts (L929 cells) were used to evaluate cell survival, and physical properties were evaluated using Fourier transform infrared spectroscopy, field emission scanning electron microscopy, a universal testing machine, and high-performance liquid chromatography. A 0.4 wt% CAE-loaded HA-Dex hybrid hydrogel patch produced the most stable release profile and the highest level of cellular activity. These hydrogel patches provided moisture and released CAE over an extended period of time, making them ideal for relieving atopic itching. This delivery system enables the extended release of CAE to localized areas and could potentially be used to apply a variety of products to treat AD. Full article

(This article belongs to the Special Issue Design, Synthesis and Characterization of Hybrid Composite Materials)

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14 pages, 2116 KiB

Open AccessArticle

Evaluation of the In Vitro and In Vivo Antitumor Efficacy of Peanut Sprout Extracts Cultivated with Fermented Sawdust Medium Against Bladder Cancer

by Hongbeom Park, Jun-Hui Song, Byungdoo Hwang, BoKyung Moon, Seok-Joong Yun, Wun-Jae Kim and Sung-Kwon Moon

Appl. Sci. 2020, 10(23), 8758; https://doi.org/10.3390/app10238758 - 7 Dec 2020

Cited by 4 | Viewed by 2336

Abstract

Peanut sprout extracts reportedly exhibit numerous beneficial effects; however, there are few investigations on the biological effects of peanut sprout extracts cultivated with fermented sawdust medium (PSEFS). Here, we examined whether PSEFS demonstrates antitumor activity against bladder cancer, in vitro and in vivo. [...] Read more.

Peanut sprout extracts reportedly exhibit numerous beneficial effects; however, there are few investigations on the biological effects of peanut sprout extracts cultivated with fermented sawdust medium (PSEFS). Here, we examined whether PSEFS demonstrates antitumor activity against bladder cancer, in vitro and in vivo. The results showed that PSEFS prohibited the proliferation of bladder cancer T24 cells, with this effect attributed to induction of cell cycle arrest at the G1 phase through reduced expression of cyclins and cyclin-dependent kinases caused by a promotion of p21^WAF1 expression. Additionally, PSEFS induced phosphorylation of p38 mitogen-activated protein kinase. Moreover, PSEFS treatment attenuated the invasive and migratory potential of T24 cells due to decreased matrix metalloproteinase-9 activity combined with downregulation of the transcriptional binding activity of SP1, activator protein -1, and nuclear factor-kappaB. Furthermore, PSEFS (20 mg/kg) attenuated the tumor-growth rate in xenograft mice bearing T24 cells, with an effect equivalent to that of cisplatin and in the absence of toxicity following weight-loss evaluation and hematobiochemical testing of PSEFS-treated mice. These results demonstrated the antitumor efficacy of PSEFS both in vitro and in vivo, thereby reporting it as a potential candidate for development of novel agents against bladder cancer. Full article

(This article belongs to the Section Food Science and Technology)

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18 pages, 4626 KiB

Open AccessArticle

Evaluation of the Biomechanical Parameters of Human-Wheelchair Systems during Ramp Climbing with the Use of a Manual Wheelchair with Anti-Rollback Devices

by Bartosz Wieczorek, Mateusz Kukla, Dominik Rybarczyk and Łukasz Warguła

Appl. Sci. 2020, 10(23), 8757; https://doi.org/10.3390/app10238757 - 7 Dec 2020

Cited by 16 | Viewed by 3259

Abstract

Purpose: The main purpose of the research conducted was the analysis of kinematic and biomechanical parameters measured during manual wheelchair ramp-climbing with the use of the anti-rollback system and the comparison of the values tested with the manual wheelchair climbing the same ramp [...] Read more.

Purpose: The main purpose of the research conducted was the analysis of kinematic and biomechanical parameters measured during manual wheelchair ramp-climbing with the use of the anti-rollback system and the comparison of the values tested with the manual wheelchair climbing the same ramp but without any modifications. The paper presents a quantitative assessment relating to the qualitative research of the anti-rollback system performed by another research team. Method and materials: The article presents the measurement results of the wheelchair motion kinematics and the activity of four upper limb muscles for eight subjects climbing a 4.58° ramp. Each subject propelled the wheelchair both with and without the anti-rollback system. The kinematic parameters were measured by means of two incremental encoders with the resolution of 500 impulses per single revolution of the measurement wheel. Whereas, the muscle activity was measured by means of surface electromyography with the use of Noraxon Mini DTS apparatus equipped with four measurement channels. Results: The surface electromyography measurement indicated an increase in the muscle activity for all four muscles, during the use of the anti-rollback system. The increase was: 18.56% for deltoid muscle anterior, 12.37% for deltoid muscle posteriori, 13.0% for triceps brachii, and 15.44% for extensor carpi radialis longus. As far as the kinematics analysis is concerned, a decrease in the measured kinematic parameters was observed in most participants. The medium velocity of the propelling cycle decreased by 26%. The ratio of the generated power and the loss power in a single propelling cycle λ had decreased by 18%. The least decrease was recorded for the measurement of mechanical energy E and the propelling cycle duration time. For the total mechanical energy, the decrease level was 3%, and for the propelling cycle duration it was 1%. The research carried out did not demonstrate any impact of the anti-rollback system use on the push phase share in the entire propelling cycle. Full article

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18 pages, 3919 KiB

Open AccessArticle

Comparisons of the Anti-Inflammatory Activity of Dendropanax morbifera LEV Leaf Extract Contents Based on the Collection Season and Concentration of Ethanol as an Extraction Solvent

by Kyeong Jin Kim, Ji Sun Youn, Young-Jun Kim and Ji Yeon Kim

Appl. Sci. 2020, 10(23), 8756; https://doi.org/10.3390/app10238756 - 7 Dec 2020

Cited by 2 | Viewed by 2748

Abstract

This study aimed to compare the anti-inflammatory activity of 10-year-old Dendropanax morbifera LEV (DM) leaf extracts. The leaves were collected during different seasons (May, August, and November), and the extracts were prepared using different methods (hot water, 30% ethanol, or 60% ethanol). Lipopolysaccharide-stimulated [...] Read more.

This study aimed to compare the anti-inflammatory activity of 10-year-old Dendropanax morbifera LEV (DM) leaf extracts. The leaves were collected during different seasons (May, August, and November), and the extracts were prepared using different methods (hot water, 30% ethanol, or 60% ethanol). Lipopolysaccharide-stimulated RAW264.7 cells were treated with these extracts for 12 h. The anti-inflammatory effects were evaluated by measuring the production of nitrite; prostaglandin E₂ (PGE₂); and inflammatory cytokines such as interleukin (IL)-6, IL-1β, and tumor necrosis factor-alpha, in addition to the mRNA expression levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 and activation of the nuclear factor κB (NF-κB)/mitogen-activated protein kinase (MAPK) pathways. The amyrin and polyphenol compositions of the extracts were analyzed using a triple time-of-flight mass spectrometer and high-performance liquid chromatography. The 30% ethanol extract harvested in May and 60% ethanol extracts collected in August and November displayed the highest inhibitions of nitrite, PGE₂, and inflammatory cytokines. The 60% ethanol extract harvested in August suppressed activation of the NF-κB and MAPK signaling pathways. The contents of amyrin and polyphenol compounds were highly dependent on the ethanol concentration used during each season. These results suggest that ethanol extracts of DM leaves may have the potential to regulate inflammatory responses. Full article

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Graphical abstract

9 pages, 2303 KiB

Open AccessFeature PaperCommunication

Bifunctional Aptamer Drug Carrier Enabling Selective and Efficient Incorporation of an Approved Anticancer Drug Irinotecan to Fibrin Gels

by Hiroto Fujita, Yuka Kataoka and Masayasu Kuwahara

Appl. Sci. 2020, 10(23), 8755; https://doi.org/10.3390/app10238755 - 7 Dec 2020

Cited by 2 | Viewed by 2794

Abstract

We have previously developed a bifunctional aptamer (bApt) binding to both human thrombin and camptothecin derivative (CPT1), and showed that bApt acts as a drug carrier under the phenomenon named selective oligonucleotide entrapment in fibrin polymers (SOEF), which enables efficient enrichment of CPT1 [...] Read more.

We have previously developed a bifunctional aptamer (bApt) binding to both human thrombin and camptothecin derivative (CPT1), and showed that bApt acts as a drug carrier under the phenomenon named selective oligonucleotide entrapment in fibrin polymers (SOEF), which enables efficient enrichment of CPT1 into fibrin gels, resulting in significant inhibition of tumor cell growth. However, although the derivative CPT1 exhibits anticancer activity, it is not an approved drug. In this study, we evaluated the binding properties of bApt to irinotecan, a camptothecin analog commonly used for anticancer drug therapy, in addition to unmodified camptothecin (CPT). Furthermore, we have revealed that irinotecan binds to bApt like CPT1 and is selectively concentrated on fibrin gels formed around the tumor cells under the SOEF phenomenon to suppress cell proliferation. Full article

(This article belongs to the Special Issue Nucleic Acids Conjugates for Biotechnological Applications)

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15 pages, 1178 KiB

Open AccessArticle

Hybrid Local and Global Deep-Learning Architecture for Salient-Object Detection

by Wajeeha Sultan, Nadeem Anjum, Mark Stansfield and Naeem Ramzan

Appl. Sci. 2020, 10(23), 8754; https://doi.org/10.3390/app10238754 - 7 Dec 2020

Cited by 3 | Viewed by 2420

Abstract

Salient-object detection is a fundamental and the most challenging problem in computer vision. This paper focuses on the detection of salient objects, especially in low-contrast images. To this end, a hybrid deep-learning architecture is proposed where features are extracted on both the local [...] Read more.

Salient-object detection is a fundamental and the most challenging problem in computer vision. This paper focuses on the detection of salient objects, especially in low-contrast images. To this end, a hybrid deep-learning architecture is proposed where features are extracted on both the local and global level. These features are then integrated to extract the exact boundary of the object of interest in an image. Experimentation was performed on five standard datasets, and results were compared with state-of-the-art approaches. Both qualitative and quantitative analyses showed the robustness of the proposed architecture. Full article

(This article belongs to the Section Computing and Artificial Intelligence)

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18 pages, 2091 KiB

Open AccessArticle

A Statistical Estimation of 5G Massive MIMO Networks’ Exposure Using Stochastic Geometry in mmWave Bands

by Maarouf Al Hajj, Shanshan Wang, Lam Thanh Tu, Soumaya Azzi and Joe Wiart

Appl. Sci. 2020, 10(23), 8753; https://doi.org/10.3390/app10238753 - 7 Dec 2020

Cited by 24 | Viewed by 3719

Abstract

This paper aims to derive an analytical modelling of the downlink exposure in 5G massive Multiple Input Multiple Output (MIMO) antenna networks using stochastic geometry. The Poisson point process (PPP) is assumed for base station (BS) distribution. The power received at the transmitter [...] Read more.

This paper aims to derive an analytical modelling of the downlink exposure in 5G massive Multiple Input Multiple Output (MIMO) antenna networks using stochastic geometry. The Poisson point process (PPP) is assumed for base station (BS) distribution. The power received at the transmitter is modeled as a shot-noise process with a modified power law. The distributions of 5G massive MIMO antenna gain and channel gain were obtained by fitting simulation results from the NYUSIM channel simulator. The fitted distributions, e.g., exponential and gamma distribution for antenna and channel gain respectively, were then implemented into an analytical framework. In this paper, we obtained the closed-form expression of the moment-generating function (MGF) for the total exposure in the network. The framework is then validated by numerical simulations. The sensitivity analysis is carried out to investigate the impact of key parameters, e.g., BS density, path loss exponent, and transmission probability. We then proved and quantified the significant impact the transmission probability on global exposure, which indicates the importance of considering the network usage in 5G exposure estimations. Full article

(This article belongs to the Special Issue Human Exposure in 5G and 6G Scenarios)

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18 pages, 7174 KiB

Open AccessReview

A Critical Review of Flood Risk Management and the Selection of Suitable Measures

by Muhammad Atiq Ur Rehman Tariq, Rashid Farooq and Nick van de Giesen

Appl. Sci. 2020, 10(23), 8752; https://doi.org/10.3390/app10238752 - 7 Dec 2020

Cited by 63 | Viewed by 19439

Abstract

Modern-day flood management has evolved into a variety of flood management alternatives. The selection of appropriate flood measures is crucial under a variety of flood management practices, approaches, and assessment criteria. Many leading countries appraise the significance of risk-based flood management, but the [...] Read more.

Modern-day flood management has evolved into a variety of flood management alternatives. The selection of appropriate flood measures is crucial under a variety of flood management practices, approaches, and assessment criteria. Many leading countries appraise the significance of risk-based flood management, but the fixed return period is still the de facto standard of flood management practices. Several measures, approaches, and design criteria have been developed over time. Understanding their role, significance, and correlation toward risk-based flood management is crucial for integrating them into a plan for a floodplain. The direct impacts of a flood are caused by direct contact with the flood, while indirect impacts occur as a result of the interruptions and disruptions of the socio-economical aspects. To proceed with a risk-based flood management approach, the fundamental requirement is to understand the risk dynamics of a floodplain and to identify the principal parameter that should primarily be addressed so as to reduce the risk. Risk is a potential loss that may arise from a hazard. On the one hand, exposure and susceptibility of the vulnerable system, and on the other, the intensity and probability of the hazard, are the parameters that can be used to quantitatively determine risk. The selection of suitable measures for a flood management scheme requires a firm apprehension of the risk mechanism. Under socio-economic and environmental constraints, several measures can be employed at the catchments, channels, and floodplains. The effectiveness of flood measures depends on the floodplain characteristics and supporting measures. Full article

(This article belongs to the Special Issue CITIES: Energetic Efficiency, Sustainability; Infrastructures, Energy and the Environment; Mobility and IoT; Governance and Citizenship)

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27 pages, 1106 KiB

Open AccessArticle

Regulatory Requirements on the Competence of Remote Operator in Maritime Autonomous Surface Ship: Situation Awareness, Ship Sense and Goal-Based Gap Analysis

by Masanori Yoshida, Etsuro Shimizu, Masashi Sugomori and Ayako Umeda

Appl. Sci. 2020, 10(23), 8751; https://doi.org/10.3390/app10238751 - 7 Dec 2020

Cited by 31 | Viewed by 6107

Abstract

Maritime Autonomous Surface Ship (MASS) has been developed recently, and demonstration projects have been carried out internationally. Considering the full autonomous level is unlikely to be addressed shortly, remote control centre and Remote Operator (RO) will play a vital role in the MASS [...] Read more.

Maritime Autonomous Surface Ship (MASS) has been developed recently, and demonstration projects have been carried out internationally. Considering the full autonomous level is unlikely to be addressed shortly, remote control centre and Remote Operator (RO) will play a vital role in the MASS system. Although competence of watchkeeping at the ship’s bridge is inevitable for RO to avoid ship accidents caused by human errors, international requirements have not been introduced yet. This paper presents a way to develop the regulatory framework on the competence of RO based on the International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (STCW) by exploring the concept of Situation Awareness (SA). Goal-Based Gap Analysis (GBGA) is constructed based on the human-behaviour model and the required information for SA. A case study through the mini focus group discussion with interviews by a total of three (3) veteran instructors of training ships is conducted utilising the information including the results of previous demonstration projects on the remote control. The results show the relationship between required information and ship sense, shortage of these factors when RO is operating, additional competence and possible regulatory requirements for RO. The findings support the usefulness of GBGA and pave the way to develop a regulatory framework for RO further. Full article

(This article belongs to the Special Issue Autonomous and Remote-Controlled Ship Operations)

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15 pages, 3904 KiB

Open AccessArticle

Soil Stabilization Using Waste Paper Fly Ash: Precautions for Its Correct Use

by Hani Baloochi, Diego Aponte and Marilda Barra

Appl. Sci. 2020, 10(23), 8750; https://doi.org/10.3390/app10238750 - 7 Dec 2020

Cited by 21 | Viewed by 5578

Abstract

This paper deals with the valorization of waste paper fly ash (WPFA) as a binder for soil stabilization. The mineralogical characterization shows the presence of free lime, as well as some non-reactive and cementitious phases. The hydration of lime is an expansive reaction [...] Read more.

This paper deals with the valorization of waste paper fly ash (WPFA) as a binder for soil stabilization. The mineralogical characterization shows the presence of free lime, as well as some non-reactive and cementitious phases. The hydration of lime is an expansive reaction and can be problematic in soil stabilization. Therefore, to study its effect on stabilized soil, an in-house experimental set-up is proposed to measure the possible expansion. Furthermore, to study the effect of water reduction and delay time on strength, unconfined compressive strength with different mixes is conducted. The obtained results showed that using WPFA causes expansion in stabilized soil, but a delay time of 30 min, after mixing the material with water and then compacting it, can decrease the expansion. Additionally, decreasing the water content by a point of Proctor can be essential for improving the strength in soil samples, even reaching the same strength values as control samples cured at 7 days. Finally, all the results obtained in this study have shown that WPFA is a suitable material for use as a binder for soil stabilization while reducing its optimum water content, adding a proper delay time, and taking into consideration WPFA’s expansive behavior at the moment of its use. Full article

(This article belongs to the Special Issue Recycling Waste in Construction Materials)

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11 pages, 3978 KiB

Open AccessArticle

BFRVSR: A Bidirectional Frame Recurrent Method for Video Super-Resolution

by Xiongxiong Xue, Zhenqi Han, Weiqin Tong, Mingqi Li and Lizhuang Liu

Appl. Sci. 2020, 10(23), 8749; https://doi.org/10.3390/app10238749 - 7 Dec 2020

Cited by 2 | Viewed by 2944

Abstract

Video super-resolution is a challenging task. One possible solution, called the sliding window method, tries to divide the generation of high-resolution video sequences into independent subtasks. Another popular method, named the recurrent algorithm, utilizes the generated high-resolution images of previous frames to generate [...] Read more.

Video super-resolution is a challenging task. One possible solution, called the sliding window method, tries to divide the generation of high-resolution video sequences into independent subtasks. Another popular method, named the recurrent algorithm, utilizes the generated high-resolution images of previous frames to generate the high-resolution image. However, both methods have some unavoidable disadvantages. The former method usually leads to bad temporal consistency and has higher computational cost, while the latter method cannot always make full use of information contained by optical flow or any other calculated features. Thus, more investigations need to be done to explore the balance between these two methods. In this work, a bidirectional frame recurrent video super-resolution method is proposed. To be specific, reverse training is proposed that also utilizes a generated high-resolution frame to help estimate the high-resolution version of the former frame. The bidirectional recurrent method guarantees temporal consistency and also makes full use of the adjacent information due to the bidirectional training operation, while the computational cost is acceptable. Experimental results demonstrate that the bidirectional super-resolution framework gives remarkable performance and it solves time-related problems. Full article

(This article belongs to the Section Computing and Artificial Intelligence)

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17 pages, 4827 KiB

Open AccessArticle

Study on Mechanical and Viscoelastic Properties of Asphalt Mixture Modified by Diatomite and Crumb Rubber Particles

by Chunyu Liang, Hao Zhang, Zhengwei Gu, Xin Xu and Jinxin Hao

Appl. Sci. 2020, 10(23), 8748; https://doi.org/10.3390/app10238748 - 7 Dec 2020

Cited by 14 | Viewed by 2887

Abstract

To optimize the properties of asphalt mixtures and make full use of waste rubber tires, diatomite and crumb rubber particles were applied to reinforce the asphalt mixtures in this study. The rutting tests, the three-point bending tests, the freeze-thaw splitting tests, and the [...] Read more.

To optimize the properties of asphalt mixtures and make full use of waste rubber tires, diatomite and crumb rubber particles were applied to reinforce the asphalt mixtures in this study. The rutting tests, the three-point bending tests, the freeze-thaw splitting tests, and the uniaxial compression creep tests were performed to analyze the effects of asphalt types and aggregate gradation on the pavement properties of diatomite and crumb rubber particles reinforced asphalt mixtures (DRPAM). Subsequently, the creep and relaxation characteristics of DRPAM were analyzed by the Burgers model, the modified Burgers model, the second-order extensive Maxwell model, and the Scott–Blair model. The results show that rubber particles and diatomite can reinforce the high temperature, low temperature, and viscoelastic properties of asphalt mixtures, although the improvement effect is weaker than styrene-butadiene-styrene (SBS). Consequently, it is concluded that rubber particle and diatomite compound modified asphalt mixture with suspension dense gradation and SBS binder will have better performance. Full article

(This article belongs to the Special Issue Monitoring and Evaluation Methodologies on Repair, (Self-)Healing, and Restoration of Materials and Structures)

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16 pages, 763 KiB

Open AccessArticle

Parsing Expression Grammars and Their Induction Algorithm

by Wojciech Wieczorek, Olgierd Unold and Łukasz Strąk

Appl. Sci. 2020, 10(23), 8747; https://doi.org/10.3390/app10238747 - 7 Dec 2020

Cited by 1 | Viewed by 2741

Abstract

Grammatical inference (GI), i.e., the task of finding a rule that lies behind given words, can be used in the analyses of amyloidogenic sequence fragments, which are essential in studies of neurodegenerative diseases. In this paper, we developed a new method that generates [...] Read more.

Grammatical inference (GI), i.e., the task of finding a rule that lies behind given words, can be used in the analyses of amyloidogenic sequence fragments, which are essential in studies of neurodegenerative diseases. In this paper, we developed a new method that generates non-circular parsing expression grammars (PEGs) and compares it with other GI algorithms on the sequences from a real dataset. The main contribution of this paper is a genetic programming-based algorithm for the induction of parsing expression grammars from a finite sample. The induction method has been tested on a real bioinformatics dataset and its classification performance has been compared to the achievements of existing grammatical inference methods. The evaluation of the generated PEG on an amyloidogenic dataset revealed its accuracy when predicting amyloid segments. We show that the new grammatical inference algorithm achieves the best ACC (Accuracy), AUC (Area under ROC curve), and MCC (Mathew’s correlation coefficient) scores in comparison to five other automata or grammar learning methods. Full article

(This article belongs to the Special Issue Applied Machine Learning)

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13 pages, 1285 KiB

Open AccessArticle

Deep-Learning Model to Predict Coronary Artery Calcium Scores in Humans from Electrocardiogram Data

by Changkyoung Eem, Hyunki Hong and Yoohun Noh

Appl. Sci. 2020, 10(23), 8746; https://doi.org/10.3390/app10238746 - 7 Dec 2020

Cited by 4 | Viewed by 2680

Abstract

We introduce a deep-learning neural network model that uses electrocardiogram (ECG) data to predict coronary artery calcium scores, which can be useful for reliably detecting cardiovascular risk in patients. In our pre-processing method, each lead of the ECG is segmented into several waves [...] Read more.

We introduce a deep-learning neural network model that uses electrocardiogram (ECG) data to predict coronary artery calcium scores, which can be useful for reliably detecting cardiovascular risk in patients. In our pre-processing method, each lead of the ECG is segmented into several waves with an interval, which is determined as the period from the starting point of a P-wave to the end point of a T-wave. The number of segmented waves of one lead represents the number of heartbeats of the subject per 10 s. The segmented waves of one cycle are transformed into normalized waves with an amplitude of 0–1. Owing to the use of eight-lead ECG waves, the input ECG dataset has two dimensions. We used a convolutional neural network with 16 layers and 5 fully connected layers, comprising a one-dimensional filter to examine the normalized wave of one lead, rather than a two-dimensional filter to examine the coherence among the unit waves of eight leads. The training and testing are repeated 10 times with a randomly assigned dataset (177,547 ECGs). Our network model achieves an average area under the receiver operating characteristic curve of 0.801–0.890, and the average accuracy is in the range of 72.9–80.6%. Full article

(This article belongs to the Section Applied Biosciences and Bioengineering)

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13 pages, 4634 KiB

Open AccessFeature PaperArticle

Impact of the Textile Mesh on the Efficiency of TRM Strengthening Solutions to Improve the Infill Walls Out-of-Plane Behaviour

by André Furtado, Hugo Rodrigues, António Arêde and Humberto Varum

Appl. Sci. 2020, 10(23), 8745; https://doi.org/10.3390/app10238745 - 7 Dec 2020

Cited by 10 | Viewed by 2967

Abstract

Different retrofitting techniques have been developed and proposed to prevent the masonry infill walls (MIW) out-of-plane collapse. Many other authors confirmed that these types of elements are vulnerable when subjected to earthquake loadings, leading to several casualties and economic losses. Based on this, [...] Read more.

Different retrofitting techniques have been developed and proposed to prevent the masonry infill walls (MIW) out-of-plane collapse. Many other authors confirmed that these types of elements are vulnerable when subjected to earthquake loadings, leading to several casualties and economic losses. Based on this, the present manuscript comprises an experimental campaign of flexure strength tests on small masonry walls to discuss the efficiency of textile-reinforced mortar (TRM) strengthening solutions to improve their out-of-plane behaviour. For this, eighteen flexural strength tests parallel to the horizontal bed joints were carried out. Nineteen masonry infill walls made with hollow clay horizontal brick, eight non-strengthened and the remaining ones strengthened with TRM. The tests were performed according to the EN 1052-2 standard. In this study, the effect of textile mesh (weak or strong) is analysed in parallel with the efficiency of the strengthening solutions. The results are presented and discussed in terms of force-displacement response parameters and damages observations. From the tests, it was observed that the TRM strengthening improved the flexural strength capacity up to 54% and the out-of-plane deformation ability about 7.18 times. Full article

(This article belongs to the Special Issue Advances on Structural Engineering, Volume II)

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25 pages, 2321 KiB

Open AccessReview

Analyzing the Improvements of Energy Management Systems for Hybrid Electric Vehicles Using a Systematic Literature Review: How Far Are These Controls from Rule-Based Controls Used in Commercial Vehicles?

by Juan P. Torreglosa, Pablo Garcia-Triviño, David Vera and Diego A. López-García

Appl. Sci. 2020, 10(23), 8744; https://doi.org/10.3390/app10238744 - 7 Dec 2020

Cited by 32 | Viewed by 5278

Abstract

The hybridization of vehicles is a viable step toward overcoming the challenge of the reduction of emissions related to road transport all over the world. To take advantage of the emission reduction potential of hybrid electric vehicles (HEVs), the appropriate design of their [...] Read more.

The hybridization of vehicles is a viable step toward overcoming the challenge of the reduction of emissions related to road transport all over the world. To take advantage of the emission reduction potential of hybrid electric vehicles (HEVs), the appropriate design of their energy management systems (EMSs) to control the power flow between the engine and the battery is essential. This work presents a systematic literature review (SLR) of the more recent works that developed EMSs for HEVs. The review is carried out subject to the following idea: although the development of novel EMSs that seek the optimum performance of HEVs is booming, in the real world, HEVs continue to rely on well-known rule-based (RB) strategies. The contribution of this work is to present a quantitative comparison of the works selected. Since several studies do not provide results of their models against commercial RB strategies, it is proposed, as another contribution, to complete their results using simulations. From these results, it is concluded that the improvement of the analyzed EMSs ranges roughly between 5% and 10% with regard to commercial RB EMSs; in comparison to the optimum, the analyzed EMSs are nearer to the optimum than commercial RB EMSs. Full article

(This article belongs to the Special Issue Energy Management Control and Optimization for Hybrid Electric Vehicles)

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12 pages, 369 KiB

Open AccessArticle

Impact of Horse Hoof Wall with Different Solid Surfaces

by Jing Zhao, Dan B. Marghitu, John Schumacher and Wenzhong Wang

Appl. Sci. 2020, 10(23), 8743; https://doi.org/10.3390/app10238743 - 7 Dec 2020

Viewed by 3214

Abstract

This study aimed to investigate the impact of a horse hoof wall on three solid surfaces: steel, concrete and asphalt. Impact experiments were conducted for different impact angles and different initial impact velocities. The effect of impact surfaces, impact angles and initial impact [...] Read more.

This study aimed to investigate the impact of a horse hoof wall on three solid surfaces: steel, concrete and asphalt. Impact experiments were conducted for different impact angles and different initial impact velocities. The effect of impact surfaces, impact angles and initial impact velocities on the coefficient of restitution and the effective coefficient of friction were tested using one-way ANOVA. Analytical and numerical modeling of the impact were developed. The impact interval was divided into two phases: compression and restitution. For compression, a contact force with a damping term was used. The restitution was characterized by an elastic contact force. The stiffness and damping coefficients of the contact force were estimated from the normal impacts. The simulated velocities after the oblique impacts were compared to the velocities in the in vitro investigation. The coefficient of restitution varied significantly on different surfaces. The effective coefficient of friction was lower on steel compared to concrete and asphalt. The model presented in this study can be applied to refine the impact simulation of the equine hoof during locomotion. Full article

(This article belongs to the Special Issue Animal Dynamics)

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10 pages, 1084 KiB

Open AccessArticle

Energy Absorption Strategies in the Lower Extremities during Double-Leg Landings in Knee Valgus Alignment

by Akihiro Tamura, Kiyokazu Akasaka and Takahiro Otsudo

Appl. Sci. 2020, 10(23), 8742; https://doi.org/10.3390/app10238742 - 7 Dec 2020

Cited by 2 | Viewed by 3751

Abstract

Landing with the knee in a valgus position may alter energy absorption strategies in the lower extremities and increase mechanical stress on the knee joint. We compared the energy absorption strategies in the lower extremities during valgus and varus landings. Seventeen females were [...] Read more.

Landing with the knee in a valgus position may alter energy absorption strategies in the lower extremities and increase mechanical stress on the knee joint. We compared the energy absorption strategies in the lower extremities during valgus and varus landings. Seventeen females were divided into valgus and varus groups. Lower extremity kinetic data were obtained during drop jumps, using a three-dimensional motion analysis system. Negative mechanical work in the lower extremities were calculated during landing. The valgus group exhibited significantly more negative mechanical work at the knee, and less negative mechanical work at the hip, compared with the varus group. However, there was no difference in the negative mechanical work at the ankle between the two groups. Findings suggest that an increased valgus landing reduces the contribution of the hip to energy absorption and is associated with a reciprocal increased contribution by the knee. Hence a knee valgus landing position may be a key biomechanical factor that increases energy absorption in the knee, thereby increasing the risk of injury. Results further indicate that this can be prevented by adopting a knee varus position on landing, which facilitates absorption of the mechanical load at the hip, rather than at the knee. Full article

(This article belongs to the Special Issue Biomechanical and Biomedical Factors of Knee Osteoarthritis)

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20 pages, 6691 KiB

Open AccessArticle

Development and Validation of Electronic Stability Control System Algorithm Based on Tire Force Observation

by Dang Lu, Yao Ma, Hengfeng Yin, Zhihui Deng and Jiande Qi

Appl. Sci. 2020, 10(23), 8741; https://doi.org/10.3390/app10238741 - 7 Dec 2020

Cited by 2 | Viewed by 3679

Abstract

In view of the higher and higher assembly rate of the electronic stability control system (ESC in short), the control accuracy still needs to be improved. In order to make up for the insufficient accuracy of the tire model in the nonlinear area [...] Read more.

In view of the higher and higher assembly rate of the electronic stability control system (ESC in short), the control accuracy still needs to be improved. In order to make up for the insufficient accuracy of the tire model in the nonlinear area of the tire, in this paper, an algorithm for the electronic stability control system based on the control of tire force feedforward used in conjunction with tire force sensors is proposed. The algorithm takes into consideration the lateral stability of the tire under extreme conditions affected by the braking force. We use linear optimal control to determine the optimal yaw moment, and obtain the brake wheel cylinder pressure through an algorithm combining feedforward compensation based on measured tire force and feedback correction. The controller structure is divided into two layers, the upper layer is controlled by a linear quadratic regulator (LQR in short) and the lower layer is controlled by PID (Proportional-integral-derivative) and feedforward. After that, verification of the controller’s algorithms using software cosimulation and hardware-in-the-loop (HIL in short) testing in the double lane change (DLC in short) and sine with dwell (SWD in short) conditions. From the test results it can be concluded that the controller based on tire force observation has partially control advantages. Full article

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8 pages, 1779 KiB

Open AccessArticle

In Situ Polymerization of Chiral Poly(fluorene-alt-benzothiadiazole) Nanocomposites with Enhanced Chirality

by Hongsub Jee, Hyeong-Sub Oh and Jaehyeong Lee

Appl. Sci. 2020, 10(23), 8740; https://doi.org/10.3390/app10238740 - 6 Dec 2020

Cited by 2 | Viewed by 2483

Abstract

Poly(fluorene-alt-benzothiadiazole) (PFBT) is a promising chiral polymer for use in metamaterials and other photonic applications, due to its large chiral optical activity at visible wavelengths. However, its usages are very limited, since it is not readily patternable into microstructures and challenging to apply [...] Read more.

Poly(fluorene-alt-benzothiadiazole) (PFBT) is a promising chiral polymer for use in metamaterials and other photonic applications, due to its large chiral optical activity at visible wavelengths. However, its usages are very limited, since it is not readily patternable into microstructures and challenging to apply to applications. In this paper, we demonstrate photo patterning of chiral PFBT/Achiral SU-8 photoresist to produce high quality structures while retaining the extraordinary chiral optical activity of our previously-reported PFBT/SU8 nanocomposite films. The ability to produce cleanly patterned microfeatures with high chirality may enable wider use of PFBT in chiral metamaterials and other photonic applications. Full article

(This article belongs to the Special Issue Nanocomposite Materials: Synthesis, Properties and Applications)

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16 pages, 19736 KiB

Open AccessArticle

Slug Regime Transitions in a Two-Phase Flow in Horizontal Round Pipe. CFD Simulations

by Vitaly Sergeev, Nikolai Vatin, Evgeny Kotov, Darya Nemova and Svyatoslav Khorobrov

Appl. Sci. 2020, 10(23), 8739; https://doi.org/10.3390/app10238739 - 6 Dec 2020

Cited by 18 | Viewed by 3912

Abstract

The main objective of the study is to propose a technical solution integrated into the pipeline for the transition of the flow regime from slug to bubbly two-phase flow. The object of research is isothermal two-phase gas–Newtonian-liquid flow in a horizontal circular pipeline. [...] Read more.

The main objective of the study is to propose a technical solution integrated into the pipeline for the transition of the flow regime from slug to bubbly two-phase flow. The object of research is isothermal two-phase gas–Newtonian-liquid flow in a horizontal circular pipeline. There is local resistance in the pipe in the form of a streamlined transverse mesh partition. The mesh partition ensures the transition of the flow from the slug regime to the bubbly regime. The purpose of the study is to propose a technical solution integrated into the pipeline for changing the flow regime of a two-phase flow from slug to bubbly flow. The method of research is a simulation using computational fluid dynamics (CFD) numerical simulation. The Navier–Stokes equations averaged by Reynolds describes the fluid motion. The k-ε models were used to close the Reynolds-averaged Navier–Stokes (RANS) equations. The computing cluster «Polytechnic—RSK Tornado» was used to solve the tasks. The results of simulation show that pressure drop on the grid did not exceed 10% of the pressure drop along the length of the pipeline. The mesh partition transits the flow regime from slug to layered one, which will help to increase the service life and operational safety of a real pipeline at insignificant energy costs to overcome the additional resistance integrated into the pipeline. Full article

(This article belongs to the Section Mechanical Engineering)

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23 pages, 4085 KiB

Open AccessReview

Physical, Chemical, and Genetic Techniques for Diatom Frustule Modification: Applications in Nanotechnology

by Alessandra Rogato and Edoardo De Tommasi

Appl. Sci. 2020, 10(23), 8738; https://doi.org/10.3390/app10238738 - 6 Dec 2020

Cited by 27 | Viewed by 6388

Abstract

Diatom frustules represent one of the most complex examples of micro- and nano-structured materials found in nature, being the result of a biomineralization process refined through tens of milions of years of evolution. They are constituted by an intricate, ordered porous silica matrix [...] Read more.

Diatom frustules represent one of the most complex examples of micro- and nano-structured materials found in nature, being the result of a biomineralization process refined through tens of milions of years of evolution. They are constituted by an intricate, ordered porous silica matrix which recently found several applications in optoelectronics, sensing, solar light harvesting, filtering, and drug delivery, to name a few. The possibility to modify the composition and the structure of frustules can further broaden the range of potential applications, adding new functions and active features to the material. In the present work the most remarkable physical and chemical techniques aimed at frustule modification are reviewed, also examining the most recent genetic techniques developed for its controlled morphological mutation. Full article

(This article belongs to the Special Issue New Frontiers in Diatom Nanotechnology)

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19 pages, 701 KiB

Open AccessArticle

LEED-EB Gold Projects for Office Spaces in Large Buildings Transitioning from Version 3 (v3) to 4 (v4): Similarities and Differences between Finland and Spain

by Svetlana Pushkar

Appl. Sci. 2020, 10(23), 8737; https://doi.org/10.3390/app10238737 - 6 Dec 2020

Cited by 9 | Viewed by 2322

Abstract

This study aims to assess the similarities and differences between Finland and Spain in terms of Leadership in Energy and Environmental Design for Existing Buildings (LEED-EB) Gold large office building-type projects transitioning from version 3 (v3) to version 4 (v4). The percentages of [...] Read more.

This study aims to assess the similarities and differences between Finland and Spain in terms of Leadership in Energy and Environmental Design for Existing Buildings (LEED-EB) Gold large office building-type projects transitioning from version 3 (v3) to version 4 (v4). The percentages of the average scores are used here to assess the achievements of the LEED-EB data. The natural logarithm of the odds ratio

(\ln θ)

and Fisher′s exact 2 × 2 tests with a mid p-value are used to evaluate dichotomous data, while the exact Wilcoxon–Mann–Whitney and Cliff′s δ effect size tests are used to evaluate ordinary data. The results for LEED-EB Gold large offices demonstrate similar certification strategies in Finland and Spain. These results may be useful to LEED-EB practitioners in Finland and Spain for facilitating the selection of appropriate certification strategies in line with identified high-performance credits for large offices. Full article

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18 pages, 4928 KiB

Open AccessArticle

Grasp Planning Pipeline for Robust Manipulation of 3D Deformable Objects with Industrial Robotic Hand + Arm Systems

by Lazher Zaidi, Juan Antonio Corrales Ramon, Laurent Sabourin, Belhassen Chedli Bouzgarrou and Youcef Mezouar

Appl. Sci. 2020, 10(23), 8736; https://doi.org/10.3390/app10238736 - 6 Dec 2020

Cited by 9 | Viewed by 4784

Abstract

In the grasping and manipulation of 3D deformable objects by robotic hands, the physical contact constraints between the fingers and the object have to be considered in order to validate the robustness of the task. Nevertheless, previous works rarely establish contact interaction models [...] Read more.

In the grasping and manipulation of 3D deformable objects by robotic hands, the physical contact constraints between the fingers and the object have to be considered in order to validate the robustness of the task. Nevertheless, previous works rarely establish contact interaction models based on these constraints that enable the precise control of forces and deformations during the grasping process. This paper considers all steps of the grasping process of deformable objects in order to implement a complete grasp planning pipeline by computing the initial contact points (pregrasp strategy), and later, the contact forces and local deformations of the contact regions while the fingers close over the grasped object (grasp strategy). The deformable object behavior is modeled using a nonlinear isotropic mass-spring system, which is able to produce potential deformation. By combining both models (the contact interaction and the object deformation) in a simulation process, a new grasp planning method is proposed in order to guarantee the stability of the 3D grasped deformable object. Experimental grasping experiments of several 3D deformable objects with a Barrett hand (3-fingered) and a 6-DOF industrial robotic arm are executed. Not only will the final stable grasp configuration of the hand + object system be obtained, but an arm + hand approaching strategy (pregrasp) will also be computed. Full article

(This article belongs to the Special Issue Automation and Robotics: Latest Achievements, Challenges and Prospects)

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18 pages, 2904 KiB

Open AccessArticle

An Efficient Estimation of the Number of Optimal Iterations for GS Pre-coding in Downlink Massive MIMO Systems

by Jae-Hyun Ro, Woon-Sang Lee, Hyun-Sun Hwang, Duckdong Hwang, Young-Hwan You and Hyoung-Kyu Song

Appl. Sci. 2020, 10(23), 8735; https://doi.org/10.3390/app10238735 - 6 Dec 2020

Cited by 1 | Viewed by 2129

Abstract

This paper proposes an estimation scheme of the number iterations for optimal Gauss–Seidel (GS) pre-coding in the downlink massive multiple input multiple output (MIMO) systems for the first time. The number of iterations in GS pre-coding is one of the key parameters and [...] Read more.

This paper proposes an estimation scheme of the number iterations for optimal Gauss–Seidel (GS) pre-coding in the downlink massive multiple input multiple output (MIMO) systems for the first time. The number of iterations in GS pre-coding is one of the key parameters and should be estimated accurately prior to signal transmission in the downlink systems. For efficient estimation without presentations of the closed-form solution for the GS pre-coding symbols, the proposed estimation scheme uses the relative method which calculates the normalized Euclidean distance (NED) between consecutive GS solutions by using the property of the monotonic decrease function of the GS solutions. Additionally, an efficient initial solution for the GS pre-coding is proposed as a two term Neumann series (NS) based on the stair matrix for improving the accuracy of estimation and accelerating the convergence rate of the GS solution. The evaluated estimation performances verify high accuracy in the downlink massive MIMO systems even in low loading factors. In addition, an additional complexity for estimating the number of the optimal iterations is nearly negligible. Full article

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31 pages, 2729 KiB

Open AccessArticle

Market-Oriented Procurement Planning Leading to a Higher Service Level and Cost Optimization

by Sergio Gallego-García and Manuel García-García

Appl. Sci. 2020, 10(23), 8734; https://doi.org/10.3390/app10238734 - 6 Dec 2020

Cited by 13 | Viewed by 5842

Abstract

The current global market situation pursues high adaptability, but why? Complexity due to mass customization is greater than ever. Globalization is no longer a theory but a fact that makes disruptions in the globalized supply chain a major risk for operations. In this [...] Read more.

The current global market situation pursues high adaptability, but why? Complexity due to mass customization is greater than ever. Globalization is no longer a theory but a fact that makes disruptions in the globalized supply chain a major risk for operations. In this context, customers demand novelty and unique experiences. These are the main drivers for market success. Therefore, existing products are now in continuous states of change with shortened product lifecycles. The purpose of this article is to analyze the impact of new market entries and product changes along the lifecycle as well as supply chain disruptions in supplier inventory levels. The goal is to minimize costs by achieving a given service level with a market-oriented procurement planning model. The model pursues minimizing the time needed to align the system with the market and, therefore, the adaptability of the system. The research compares classical inventory management models with the new proposed approach by means of simulation with the system dynamics methodology. The results show how the proposed model increased the delivery service level, reduced inventory costs, and increased the utilization of resources due to lower demand uncertainty. Therefore, the developed model is able to plan the inventory supply with a low risk of stock outages. The conclusion proposes a differentiated forecasting and inventory strategy depending on the product lifecycle stage. The developed market-oriented procurement planning model provides guidance for inventory managers regarding how to optimize their operations as an opportunity within the fourth industrial revolution to develop information technology (IT) systems to gather and utilize demand and inventory data with real-time efficiency. Full article

(This article belongs to the Special Issue Special Issue of the Manufacturing Engineering Society 2020 (SIMES-2020))

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