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Volume 9
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Appl. Sci., Volume 9, Issue 4 (February-2 2019) – 199 articles

Cover Story (view full-size image): The terrestrial basal paravian theropod, Anchiornis, running to capture a prey or to escape from a predator, had an initial absolute velocity that was not fast enough to glide up to any tree. However, this would be feasible under the help of upslope wind. Then, the Anchiornis could easily parachute from the branch of a tree to the ground or any other lower position. Later, it could practice gliding from the top branch of one tree to another under the action of the potential energy of gravity by adjusting its orientation during gliding. View Paper here.
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15 pages, 3061 KiB  
Article
Dynamic Phase Measuring Profilometry Based on Tricolor Binary Fringe Encoding Combined Time-Division Multiplexing
by Guangkai Fu, Yiping Cao, Yapin Wang, Yingying Wan, Lu Wang and Chengmeng Li
Appl. Sci. 2019, 9(4), 813; https://doi.org/10.3390/app9040813 - 25 Feb 2019
Cited by 13 | Viewed by 4800
Abstract
A dynamic phase measuring profilometry (PMP) based on tricolor binary fringe combined time-division multiplexing principle is proposed. Only one tricolor binary fringe combined by red (R), green (G), and blue (B) binary fringes with the same fringe width but without any color overlapping [...] Read more.
A dynamic phase measuring profilometry (PMP) based on tricolor binary fringe combined time-division multiplexing principle is proposed. Only one tricolor binary fringe combined by red (R), green (G), and blue (B) binary fringes with the same fringe width but without any color overlapping one another is needed and sent into the flash memory of a high-speed digital light projector (HDLP) in advance. A specialized time-division multiplexing timing sequence is designed to control the HDLP to project the tricolor binary fringe saved in the flash memory onto the measured dynamic object separately and sequentially at 234 fps, at the same time, the projected light source mode is set as monochrome mode which means that all the RGB LEDs remain lighting. Meanwhile, it also triggers a high frame rate monochrome camera synchronized with the HDLP to capture the corresponding deformed patterns in R, G and B channels. By filtering, the nearly unbroken phase-shifting sinusoidal deformed patterns for three-step PMP can be extracted from the captured deformed patterns. It is equivalent to the three-dimensional (3D) shape reconstruction of the measured dynamic object at 78 fps. Experimental results verify the feasibility and the validity of the proposed method. It is effective for measuring the dynamic object and can avoid the color cross-talk effectively. Full article
(This article belongs to the Special Issue High-speed Optical 3D Shape and Deformation Measurement)
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16 pages, 7257 KiB  
Article
A Novel Method to Assess Safety of Buried Pressure Pipelines under Non-Random Process Seismic Excitation based on Cloud Model
by Peng Zhang, Yihuan Wang and Guojin Qin
Appl. Sci. 2019, 9(4), 812; https://doi.org/10.3390/app9040812 - 25 Feb 2019
Cited by 6 | Viewed by 2906
Abstract
It is necessary to conduct a safety assessment for pipelines which are regarded as important lifeline projects after an earthquake. Since the random process of loading in earthquake engineering requires a large amount of samples, this paper establishes a non-random vibration method based [...] Read more.
It is necessary to conduct a safety assessment for pipelines which are regarded as important lifeline projects after an earthquake. Since the random process of loading in earthquake engineering requires a large amount of samples, this paper establishes a non-random vibration method based on convex model theory and applies it to small sample engineering. Moreover, a space–time analytical model of buried pipeline and a finite element model are established to solve the dynamic response of pipelines with non-random process seismic excitation. Furthermore, the randomness of the stress values of the pipeline subjected to earthquake and the fuzziness of the degree of damage to pipelines are considered. Therefore, a novel method for assessing damage to pipelines is proposed based on cloud model. The results indicate that an analysis of non-random vibration combined with the cloud inference method can solve the fuzziness and randomness of the quantitative description and qualitative concept conversion for damage evaluation of pipelines. The method is also an adaptive and effective assessment method for pipelines exposed to earthquake and is able to promote safety management of pipeline engineering. Full article
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13 pages, 4356 KiB  
Review
The Adoption of Three-Dimensional Additive Manufacturing from Biomedical Material Design to 3D Organ Printing
by Ajay Vikram Singh, Mohammad Hasan Dad Ansari, Shuo Wang, Peter Laux, Andreas Luch, Amit Kumar, Rajendra Patil and Stephan Nussberger
Appl. Sci. 2019, 9(4), 811; https://doi.org/10.3390/app9040811 - 25 Feb 2019
Cited by 46 | Viewed by 9600
Abstract
Three-dimensional (3D) bioprinting promises to change future lifestyle and the way we think about aging, the field of medicine, and the way clinicians treat ailing patients. In this brief review, we attempt to give a glimpse into how recent developments in 3D bioprinting [...] Read more.
Three-dimensional (3D) bioprinting promises to change future lifestyle and the way we think about aging, the field of medicine, and the way clinicians treat ailing patients. In this brief review, we attempt to give a glimpse into how recent developments in 3D bioprinting are going to impact vast research ranging from complex and functional organ transplant to future toxicology studies and printed organ-like 3D spheroids. The techniques were successfully applied to reconstructed complex 3D functional tissue for implantation, application-based high-throughput (HTP) platforms for absorption, distribution, metabolism, and excretion (ADME) profiling to understand the cellular basis of toxicity. We also provide an overview of merits/demerits of various bioprinting techniques and the physicochemical basis of bioink for tissue engineering. We briefly discuss the importance of universal bioink technology, and of time as the fourth dimension. Some examples of bioprinted tissue are shown, followed by a brief discussion on future biomedical applications. Full article
(This article belongs to the Special Issue Nanomaterials for Bone Tissue Engineering)
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13 pages, 2309 KiB  
Article
A Novel CAD Tool for Electric Educational Diagrams
by Patricia Ruiz and Bernabé Dorronsoro
Appl. Sci. 2019, 9(4), 810; https://doi.org/10.3390/app9040810 - 25 Feb 2019
Cited by 1 | Viewed by 6398
Abstract
Computer-aided design (CAD) is a technological revolution, very powerful and with large applicability to problem solving. It is essential in many different disciplines ranging from architecture to education, medicine, physics, or gaming. In this work, we propose a novel CAD tool, called CADDi, [...] Read more.
Computer-aided design (CAD) is a technological revolution, very powerful and with large applicability to problem solving. It is essential in many different disciplines ranging from architecture to education, medicine, physics, or gaming. In this work, we propose a novel CAD tool, called CADDi, to assist in the design of electric diagrams in the educational context. We are applying the theory of formal languages to create WDLang, an easy-to-use, highly expressive, unequivocal, and correct programming language for designing electric circuits. This programming language is the cornerstone of CADDi, which automatically generates the equivalent ladder diagram (explains the circuit operation) to the programmed circuit, offering additional features that allow analysis of its functionality in an interactive way. It also offers a graphical interface to directly design ladder diagrams, or to modify the automatically generated ones. The existing electrical CAD tools are either very simple, e.g., for creating good-looking diagrams with no functionality, or too complex, for professional systems design. CADDi is extremely useful for learning purposes. It assists users on how to generate ladder diagrams, and on understanding the behavior of electrical circuits. Additionally, it serves as an assessment tool for self-evaluation in the translation from wiring diagrams to ladder ones. In order to make CADDi highly accessible, it was implemented as a web page. Full article
(This article belongs to the Section Computing and Artificial Intelligence)
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21 pages, 13695 KiB  
Article
An Adaptive Neuro-Fuzzy Inference Model to Predict Punching Shear Strength of Flat Concrete Slabs
by Mohammed A. Mashrei and Alaa M. Mahdi
Appl. Sci. 2019, 9(4), 809; https://doi.org/10.3390/app9040809 - 25 Feb 2019
Cited by 8 | Viewed by 3286
Abstract
An adaptive neuro-fuzzy inference system (ANFIS)-based model was developed to predict the punching shear strength of flat concrete slabs without shear reinforcement. The model was developed using a database collected from 207 experiments available in the existing literature. Five key input parameters were [...] Read more.
An adaptive neuro-fuzzy inference system (ANFIS)-based model was developed to predict the punching shear strength of flat concrete slabs without shear reinforcement. The model was developed using a database collected from 207 experiments available in the existing literature. Five key input parameters were used to build the model, which were slab effective depth, concrete strength, reinforcement ratio, yield tensile strength of reinforcement, and width of square loaded area. The output parameter of the model was punching shear strength. The results from the adaptive neural fuzzy inference model were compared to those from the simplified punching shear equations of ACI, BS-8110, Model Code 2010, Euro-Code 2, and also experimental results. The root mean square error (RMSE) and the correlation coefficient (R) were used as evaluation criteria. Parametric studies were presented using ANFIS to assess the effect of each input parameter on the punching shear strength and to compare ANFIS results to those from the equations proposed in commonly used codes. The results showed that the ANFIS model is simple and provided the most accurate predictions of the punching shear strength of two-way flat concrete slabs without shear reinforcement. Full article
(This article belongs to the Section Materials Science and Engineering)
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19 pages, 5420 KiB  
Article
A Compressed Equivalent Source Method Based on Equivalent Redundant Dictionary for Sound Field Reconstruction
by Yansong He, Liangsong Chen, Zhongming Xu and Zhifei Zhang
Appl. Sci. 2019, 9(4), 808; https://doi.org/10.3390/app9040808 - 25 Feb 2019
Cited by 14 | Viewed by 3094
Abstract
The equivalent source method (ESM) based on compressive sensing (CS) requires that the source has a sparse or approximately sparse representation in a suitable basis or dictionary. However, in practical applications, it is not easy to find the appropriate basis or dictionary due [...] Read more.
The equivalent source method (ESM) based on compressive sensing (CS) requires that the source has a sparse or approximately sparse representation in a suitable basis or dictionary. However, in practical applications, it is not easy to find the appropriate basis or dictionary due to the indeterminate characteristics of the source. To solve this problem, an equivalent redundant dictionary is constructed, which contains two core parts: one is the equivalent dictionary used in the CS-based ESMs under the sparse assumption, and the other one is the orthogonal basis obtained by the singular value decomposition (SVD). On this foundation, a method named compressed ESM based on the equivalent redundant dictionary (ERDCESM) is proposed to enhance the performances of source field reconstruction for different types of sources. Moreover, inspired by the idea of functional beamforming (FB), ERDCESM with order v (ERDCESM- v ) can possess a high dynamic range when detecting the source location. The numerical simulations are carried out at different frequencies to evaluate the performance of the proposed method, and the results suggest that the proposed method performs well both for sparse and even spatially extended sources. The validity and practicality of the proposed method are also verified by the experimental results. Full article
(This article belongs to the Section Acoustics and Vibrations)
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17 pages, 4279 KiB  
Article
Hemodynamics and Wall Mechanics after Surgical Repair of Aortic Arch: Implication for Better Clinical Decisions
by Siyeong Ju, Ibrahim Abdullah, Shengmao Lin and Linxia Gu
Appl. Sci. 2019, 9(4), 807; https://doi.org/10.3390/app9040807 - 25 Feb 2019
Cited by 4 | Viewed by 4410
Abstract
Graft repair of aortic coarctation is commonly used to mimic the physiological aortic arch shape and function. Various graft materials and shapes have been adopted for the surgery. The goal of this work is to quantitatively assess the impact of graft materials and [...] Read more.
Graft repair of aortic coarctation is commonly used to mimic the physiological aortic arch shape and function. Various graft materials and shapes have been adopted for the surgery. The goal of this work is to quantitatively assess the impact of graft materials and shapes in the hemodynamics and wall mechanics of the restored aortic arch and its correlation with clinical outcomes. A three-dimensional aortic arch model was reconstructed from magnetic resonance images. The fluid–structure interaction (FSI) analysis was performed to characterize the hemodynamics and solid wall mechanics of the repaired aortic arch. Two graft shapes (i.e., a half-moon shape and a crescent one) were considered. Material choices of the aortic arch repair included three commonly used graft materials (i.e., polytetrafluoroethylene (PTFE) synthetic graft, CorMatrix extracellular matrix, and pulmonary homograft) as well as one native tissue serving as a control. The pathological hemodynamic parameters, in terms of the percentage area of low wall shear stress (WSS), high oscillatory shear index (OSI), and high relative residence time (RRT), were quantified to be associated with potential clinical outcomes. Results have shown that the peak von Mises stress for the aortic arch repaired by the crescent graft was 76% less than that of the half-moon graft. Flow disturbance and recirculation were also minimized with the crescent graft. Moreover, pathological hemodynamic parameters were significantly reduced with the crescent graft. The graft material mismatch with the surrounding tissue aggregated the stress concentration on the aortic wall, but had minimal impact on flow dynamics. The present work demonstrated the role and importance of the graft geometry and materials on hemodynamics and wall mechanics, which could guide optimal graft decisions towards better clinical outcomes. Full article
(This article belongs to the Section Applied Biosciences and Bioengineering)
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10 pages, 3557 KiB  
Article
Breast Cancer Diagnosis by Surface-Enhanced Raman Scattering (SERS) of Urine
by Vlad Moisoiu, Andreea Socaciu, Andrei Stefancu, Stefania D. Iancu, Imre Boros, Cristian D. Alecsa, Claudiu Rachieriu, Angelica R. Chiorean, Daniela Eniu, Nicolae Leopold, Carmen Socaciu and Dan T. Eniu
Appl. Sci. 2019, 9(4), 806; https://doi.org/10.3390/app9040806 - 25 Feb 2019
Cited by 68 | Viewed by 7553
Abstract
Background: There is an ongoing research for breast cancer diagnostic tools that are cheaper, more accurate and more convenient than mammography. Methods: In this study, we employed surface-enhanced Raman scattering (SERS) for analysing urine from n = 53 breast cancer patients and n [...] Read more.
Background: There is an ongoing research for breast cancer diagnostic tools that are cheaper, more accurate and more convenient than mammography. Methods: In this study, we employed surface-enhanced Raman scattering (SERS) for analysing urine from n = 53 breast cancer patients and n = 22 controls, with the aim of discriminating between the two groups using multivariate data analysis techniques such as principal component analysis—linear discriminant analysis (PCA-LDA). The SERS spectra were acquired using silver nanoparticles synthesized by reduction with hydroxylamine hydrochloride, which were additionally activated with Ca2+ 10−4 M. Results: The addition of Ca(NO3)2 10−4 M promoted the specific adsorption to the metal surface of the anionic purine metabolites such as uric acid, xanthine and hypoxanthine. Moreover, the SERS spectra of urine were acquired without any filtering or processing step for removing protein traces and other contaminants. Using PCA-LDA, the SERS spectra of urine from breast cancer patients were classified with a sensitivity of 81%, a specificity of 95% and an overall accuracy of 88%. Conclusion: The results of this preliminary study contribute to the translation of SERS in the clinical setting and highlight the potential of SERS as a novel screening strategy for breast cancer. Full article
(This article belongs to the Special Issue Surfaced Enhanced Raman Scattering (SERS) in Disease Diagnosis)
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12 pages, 1574 KiB  
Article
Effect of Slag Particle Size on Fracture Toughness of Concrete
by Chung-Ho Huang, Chung-Hao Wu, Shu-Ken Lin and Tsong Yen
Appl. Sci. 2019, 9(4), 805; https://doi.org/10.3390/app9040805 - 25 Feb 2019
Cited by 10 | Viewed by 3799
Abstract
The effects of particle size of ground granulated blast furnace slag (GGBS) on the fracture energy, critical stress intensity, and strength of concrete are experimentally studied. Three fineness levels of GGBS of 4000, 5000, 6000 cm2/g were used. In addition to [...] Read more.
The effects of particle size of ground granulated blast furnace slag (GGBS) on the fracture energy, critical stress intensity, and strength of concrete are experimentally studied. Three fineness levels of GGBS of 4000, 5000, 6000 cm2/g were used. In addition to the control mixture without slag, two slag replacement levels of 20% and 40% by weight of the cementitious material were selected for preparing the concrete mixtures. The control mixture was designed to have a target compressive strength at 28 days of 62 MPa, while the water to cementitious material ratio was selected as 0.35 for all mixtures. Test results indicate that using finer slag in concrete may improve the filling effect and the reactivity of slag, resulting in a larger strength enhancement. The compressive strength of slag concrete was found to increase in conjunction with the fineness level of the slag presented in the mixture. Use of finer slag presents a beneficial effect on the fracture energy (GF) of concrete, even at an early age, and attains a higher increment of GF at later age (56 days). This implicates that the finer slag can have a unique effect on the enhancement of the fracture resistance of concrete. The test results of the critical stress intensity factor (KSIC) of the slag concretes have a similar tendency as that of the fracture energy, indicating that the finer slag may present an increase in the fracture toughness of concrete. Full article
(This article belongs to the Special Issue Fatigue and Fracture of Non-metallic Materials and Structures)
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12 pages, 5353 KiB  
Article
The Electronic Properties of Silicon Nanowires during Their Dissolution under Simulated Physiological Conditions
by Annina M. Steinbach, Tanja Sandner, Madeleine Nilsen, Ximeng Hua, Ragul Sivakumar, Dorin Geiger, Ardeshir Moeinian and Steffen Strehle
Appl. Sci. 2019, 9(4), 804; https://doi.org/10.3390/app9040804 - 25 Feb 2019
Cited by 3 | Viewed by 4733
Abstract
Silicon nanowires are considered promising future biomedical sensors. However, their limited stability under physiological conditions poses a challenge in sensor development and necessitates a significantly improved knowledge of underlying effects as well as new solutions to enhance silicon nanowire durability. In the present [...] Read more.
Silicon nanowires are considered promising future biomedical sensors. However, their limited stability under physiological conditions poses a challenge in sensor development and necessitates a significantly improved knowledge of underlying effects as well as new solutions to enhance silicon nanowire durability. In the present study, we deduced the dissolution rates of silicon nanowires under simulated physiological conditions from atomic force microscopy measurements. We correlated the relevant change in nanowire diameter to changes in the electronic properties by examining the I-V characteristics of kinked silicon nanowire p–n junctions. Contact potential difference measurements and ambient pressure photoemission spectroscopy additionally gave insights into the electronic surface band structure. During the first week of immersion, the Fermi level of n-type silicon nanowires shifted considerably to higher energies, partly even above the conduction band edge, which manifested in an increased conductivity. After about a week, the Fermi level stabilized and the conductivity decreased consistently with the decreasing diameter caused by continuous nanowire dissolution. Our results show that a physiological environment can substantially affect the surface band structure of silicon nanowire devices, and with it, their electronic properties. Therefore, it is necessary to study these effects and find strategies to gain reliable biomedical sensors. Full article
(This article belongs to the Special Issue Silicon Nanowires and Their Applications)
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7 pages, 1411 KiB  
Article
A Novel Coding Based Dimming Scheme with Constant Transmission Efficiency in VLC Systems
by Yu Zuo and Jian Zhang
Appl. Sci. 2019, 9(4), 803; https://doi.org/10.3390/app9040803 - 25 Feb 2019
Cited by 10 | Viewed by 2885
Abstract
Visible light communication (VLC) has attracted tremendous attention due to two functions: communication and illumination. Both reliable data transmission and lighting quality need to be considered when the transmitted signal is designed. To achieve the desired levels of illumination, dimming control is an [...] Read more.
Visible light communication (VLC) has attracted tremendous attention due to two functions: communication and illumination. Both reliable data transmission and lighting quality need to be considered when the transmitted signal is designed. To achieve the desired levels of illumination, dimming control is an essential technology applied in VLC systems. In this paper, we propose a block coding-based dimming scheme to construct the codeword set, where dimming control can be achieved by changing the ratio of two levels (ON and OFF) based on on-off keying (OOK) modulation. Simulation results show that the proposed scheme can maintain good error performance with constant transmission efficiency under various dimming levels. Full article
(This article belongs to the Special Issue Optical Communications and Networking: Prospects in Industrial Applications)
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18 pages, 5771 KiB  
Review
Electrically Driven Micro- and Nano-Scale Semiconductor Light Sources
by You-Shin No
Appl. Sci. 2019, 9(4), 802; https://doi.org/10.3390/app9040802 - 25 Feb 2019
Cited by 4 | Viewed by 4846
Abstract
Emerging optical technology capable of addressing the limits in modern electronics must incorporate unique solutions to bring about a revolution in high-speed, on-chip data communication and information processing. Among the possible optical devices that can be developed, the electrically driven, ultrasmall semiconductor light [...] Read more.
Emerging optical technology capable of addressing the limits in modern electronics must incorporate unique solutions to bring about a revolution in high-speed, on-chip data communication and information processing. Among the possible optical devices that can be developed, the electrically driven, ultrasmall semiconductor light source is the most essential element for a compact, power-efficient photonic integrated circuit. In this review, we cover the recent development of the electrically driven light-emitting devices based on various micro- and nano-scale semiconductor optical cavities. We also discuss the recent advances in the integration of these light sources with passive photonic circuits. Full article
(This article belongs to the Special Issue Novel Advances in Optical Micro- and Nano-Cavities)
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10 pages, 2728 KiB  
Article
Anticancer Efficacy of Long-Term Stored Plasma-Activated Medium
by Ngoc Hoan Nguyen, Hyung Jun Park, Soon Young Hwang, Jong-Soo Lee and Sang Sik Yang
Appl. Sci. 2019, 9(4), 801; https://doi.org/10.3390/app9040801 - 25 Feb 2019
Cited by 13 | Viewed by 4391
Abstract
The therapeutic potential of nonthermal atmospheric-pressure plasma for cancer treatment via generation of reactive species, induction of decreased mitochondrial membrane potential, and sequential apoptosis has been reported in our previous studies. Nonthermal atmospheric-pressure plasma-activated medium produced by jetting air plasma above a liquid [...] Read more.
The therapeutic potential of nonthermal atmospheric-pressure plasma for cancer treatment via generation of reactive species, induction of decreased mitochondrial membrane potential, and sequential apoptosis has been reported in our previous studies. Nonthermal atmospheric-pressure plasma-activated medium produced by jetting air plasma above a liquid surface shows advantages over direct plasma such as storage and delivery to tissues inside the body. In this study, we demonstrated that plasma-activated medium can be stored for up to 6 months in a freezer and that the stored plasma-activated medium has anticancer effects similar to those of direct plasma. Plasma-activated medium stored for 6 months showed cytocidal effects on human cervical cancer HeLa cells that were comparable to the effects of fresh plasma-activated medium or direct plasma. Furthermore, the levels of reactive species in plasma-activated medium persisted for up to 6 months. These results indicate that therapeutic application of plasma-activated medium is applicable in plasma medicine and is a promising anticancer strategy. Full article
(This article belongs to the Special Issue Plasma Technology for Biomedical Applications)
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21 pages, 526 KiB  
Article
Dynamic Rating of Three-Core XLPE Submarine Cables for Offshore Wind Farms
by Thomas V. M. Nielsen, Simon Jakobsen and Mehdi Savaghebi
Appl. Sci. 2019, 9(4), 800; https://doi.org/10.3390/app9040800 - 25 Feb 2019
Cited by 11 | Viewed by 8693
Abstract
This article aims to determine the most suitable cross-sectional area for a high voltage alternating current (HVAC) submarine cable in the design phase of new projects. A thermal ladder network method (LNM) was used to analyse the thermal behaviour in the centre of [...] Read more.
This article aims to determine the most suitable cross-sectional area for a high voltage alternating current (HVAC) submarine cable in the design phase of new projects. A thermal ladder network method (LNM) was used to analyse the thermal behaviour in the centre of the conductor as the hottest spot of the cable. On the basis of the calculated cable parameters and a thermal cable analysis of transient conditions applied by a step function with a time duration greater than 1 h, this article proposes a method for a dynamic rating of submarine cables. The dynamic rating is accomplished through an iterative process. The method was tested with a MATLAB simulation and validated in comparison with a finite element method (FEM)-based approach. Full article
(This article belongs to the Special Issue Offshore Wind Energy)
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25 pages, 941 KiB  
Article
Bio-Inspired Structure and Behavior of Self-Recovery Quadruped Robot with a Limited Number of Functional Legs
by Sarun Chattunyakit, Yukinori Kobayashi, Takanori Emaru and Ankit A. Ravankar
Appl. Sci. 2019, 9(4), 799; https://doi.org/10.3390/app9040799 - 25 Feb 2019
Cited by 11 | Viewed by 4985
Abstract
In this study, the authors focus on the structural design of and recovery methods for a damaged quadruped robot with a limited number of functional legs. Because the pre-designed controller cannot be executed when the robot is damaged, a control strategy to avoid [...] Read more.
In this study, the authors focus on the structural design of and recovery methods for a damaged quadruped robot with a limited number of functional legs. Because the pre-designed controller cannot be executed when the robot is damaged, a control strategy to avoid task failures in such a scenario should be developed. Not only the control method but also the shape and structure of the robot itself are significant for the robot to be able to move again after damage. We present a caterpillar-inspired quadruped robot (CIQR) and a self-learning mudskipper inspired crawling (SLMIC) algorithm in this research. The CIQR is realized by imitating the prolegs of caterpillars and by using a numerical optimization technique. A reinforcement learning method called Q-learning is employed to improve the adaptability of locomotion based on the crawling behavior of mudskipper. The results show that the proposed robotic platform and recovery method can improve the moving ability of the damaged quadruped robot with a few active legs in both simulations and experiments. Moreover, we obtained satisfactory results showing that a damaged multi-legged robot with at least one leg could travel properly along the required direction. Furthermore, the presented algorithm can successfully be employed in a damaged quadruped robot with fewer than four legs. Full article
(This article belongs to the Special Issue Advanced Mobile Robotics)
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20 pages, 6210 KiB  
Article
Research on the Collision Avoidance Algorithm for Fixed-Wing UAVs Based on Maneuver Coordination and Planned Trajectories Prediction
by Yu Wan, Jun Tang and Songyang Lao
Appl. Sci. 2019, 9(4), 798; https://doi.org/10.3390/app9040798 - 25 Feb 2019
Cited by 15 | Viewed by 5092
Abstract
This paper presents a novel collision avoidance (CA) algorithm for a cooperative fixed-wing unmanned aerial vehicle (UAV). The method is based on maneuver coordination and planned trajectory prediction. Each aircraft in a conflict generates three available maneuvers and predicts the corresponding planned trajectories. [...] Read more.
This paper presents a novel collision avoidance (CA) algorithm for a cooperative fixed-wing unmanned aerial vehicle (UAV). The method is based on maneuver coordination and planned trajectory prediction. Each aircraft in a conflict generates three available maneuvers and predicts the corresponding planned trajectories. The algorithm coordinates planned trajectories between participants in a conflict, determines which combination of planned trajectories provides the best separation, eventually makes an agreement on the maneuver for collision avoidance and activates the preferred maneuvers when a collision is imminent. The emphasis is placed on providing protection for UAVs, while activating maneuvers late enough to reduce interference, which is necessary for collision avoidance in the formation and clustering of UAVs. The CA has been validated with various simulations to show the advantage of collision avoidance for continuous conflicts in multiple, high-dynamic, high-density and three-dimensional (3D) environments. It eliminates the disadvantage of traditional CA, which has high uncertainty, and takes the performance parameters of different aircraft into consideration and makes full use of the maneuverability of fixed-wing aircraft. Full article
(This article belongs to the Special Issue Unmanned Aerial Vehicles (UAVs))
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40 pages, 8847 KiB  
Review
Biosensor Applications of Electrodeposited Nanostructures
by Keith J. Stine
Appl. Sci. 2019, 9(4), 797; https://doi.org/10.3390/app9040797 - 24 Feb 2019
Cited by 43 | Viewed by 7759
Abstract
The development of biosensors for a range of analytes from small molecules to proteins to oligonucleotides is an intensely active field. Detection methods based on electrochemistry or on localized surface plasmon responses have advanced through using nanostructured electrodes prepared by electrodeposition, which is [...] Read more.
The development of biosensors for a range of analytes from small molecules to proteins to oligonucleotides is an intensely active field. Detection methods based on electrochemistry or on localized surface plasmon responses have advanced through using nanostructured electrodes prepared by electrodeposition, which is capable of preparing a wide range of different structures. Supported nanoparticles can be prepared by electrodeposition through applying fixed potentials, cycling potentials, and fixed current methods. Nanoparticle sizes, shapes, and surface densities can be controlled, and regular structures can be prepared by electrodeposition through templates. The incorporation of multiple nanomaterials into composite films can take advantage of the superior and potentially synergistic properties of each component. Nanostructured electrodes can provide supports for enzymes, antibodies, or oligonucleotides for creating sensors against many targets in areas such as genomic analysis, the detection of protein antigens, or the detection of small molecule metabolites. Detection can also be performed using electrochemical methods, and the nanostructured electrodes can greatly enhance electrochemical responses by carefully designed schemes. Biosensors based on electrodeposited nanostructures can contribute to the advancement of many goals in bioanalytical and clinical chemistry. Full article
(This article belongs to the Special Issue Nano-Biointerface for Biosensing)
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11 pages, 4473 KiB  
Article
Validation of a Methodology to Analyze the Morphological Parameters in Newly Created Tidal Channels Through a Video Monitoring System
by Pablo Agudo, María Luisa Sámano, Adrián Rodríguez, Jorge Crespo, Manuel Masías, Luis Dzul and Santos Gracia
Appl. Sci. 2019, 9(4), 796; https://doi.org/10.3390/app9040796 - 24 Feb 2019
Cited by 2 | Viewed by 2978
Abstract
A video monitoring system has been used in order to track the morphology of an estuary located in La Rabia, due to the high time-space resolution provided by this system. Moreover, the data collection infrastructure allows us to extract relevant information at a [...] Read more.
A video monitoring system has been used in order to track the morphology of an estuary located in La Rabia, due to the high time-space resolution provided by this system. Moreover, the data collection infrastructure allows us to extract relevant information at a relatively low cost. The methodology used to make the image capture and its post-processing procedure, permitted the detection and monitoring of a new tidal channel appearance as well as its evolution in width until it achieved equilibrium. During the course towards this balance, we could observe the characteristic phenomena for this type of process such as incisional narrowing and increase in width. Full article
(This article belongs to the Special Issue Future-Ready Sustainable Infrastructure Systems)
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15 pages, 4152 KiB  
Article
Coupling Ultrasound with Heat-Reflux to Improve the Extraction of Quercetin, Kaempferol, Ginkgetin and Sciadopitysin from Mairei Yew Leaves
by Chunjian Zhao, Xueting Ren, Chunying Li, Hongwei Jiang, Jiajing Guan, Weiran Su, Yuzheng Li, Yao Tian, Tingting Wang and Shen Li
Appl. Sci. 2019, 9(4), 795; https://doi.org/10.3390/app9040795 - 24 Feb 2019
Cited by 6 | Viewed by 4279
Abstract
The coupling of ultrasound and heat–reflux extraction (UHRE) was developed for separation for quercetin (QU), kaempferol (KA), ginkgetin (GI) and sciadopitysin (SC) from Mairei Yew leaves. The Box–Behnken design was used to optimize the UHRE conditions for obtaining the maximum yield of flavonoids. [...] Read more.
The coupling of ultrasound and heat–reflux extraction (UHRE) was developed for separation for quercetin (QU), kaempferol (KA), ginkgetin (GI) and sciadopitysin (SC) from Mairei Yew leaves. The Box–Behnken design was used to optimize the UHRE conditions for obtaining the maximum yield of flavonoids. The optimal extraction conditions were as follows: boiling 80% methanol (V/V) for extraction solvent, 20 min for the extraction time, 200 W for the ultrasonic power and 26 mL/g for the liquid–solid ratio. By UHRE, the yields of QU, KA, GI and SC were, respectively, 0.109, 0.406, 0.031 and 0.355 mg/g, and total yield of four flavonoids was 0.901 mg/g, which were, respectively, 1.25-fold and 1.23-fold higher than those by using ultrasonic-assisted extraction (UAE) and heating reflux extraction (HRE). Moreover, the extraction time for the equilibrium yields of flavonoids using UHRE was 83.3% and 27.8%, respectively, less than the corresponding time using UAE and HRE. Compared with HRE and UAE, UHRE showed the increase of cell disruption degree as observed by scanning electron microscopy, which may be the reason for high yield and rapid extraction of target compounds. Full article
(This article belongs to the Section Chemical and Molecular Sciences)
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18 pages, 3125 KiB  
Article
Distributed Face Recognition Based on Load Balancing and Dynamic Prediction
by Fangyuan Zou, Jing Li and Weidong Min
Appl. Sci. 2019, 9(4), 794; https://doi.org/10.3390/app9040794 - 24 Feb 2019
Cited by 6 | Viewed by 3693
Abstract
With the dramatic expansion of large-scale videos, traditional centralized face recognition methods cannot meet the demands of time efficiency and expansibility, and thus distributed face recognition models were proposed. However, the number of tasks at the agent side is always dynamic, and unbalanced [...] Read more.
With the dramatic expansion of large-scale videos, traditional centralized face recognition methods cannot meet the demands of time efficiency and expansibility, and thus distributed face recognition models were proposed. However, the number of tasks at the agent side is always dynamic, and unbalanced allocation will lead to time delay and a sharp increase of CPU utilization. To this end, a new distributed face recognition framework based on load balancing and dynamic prediction is proposed in this paper. The framework consists of a server and multiple agents. When performing face recognition, the server is used to recognize faces, and other operations are performed by the agents. Since the changes of the total number of videos and the number of pedestrians affect the task amount, we perform load balancing with an improved genetic algorithm. To ensure the accuracy of task allocation, we use extreme learning machine to predict the change of tasks. The server then performs task allocation based on the predicted results sent by the agents. The experimental results show that the proposed method can effectively solve the problem of unbalanced task allocation at the agent side, and meanwhile alleviate time delay and the sharp increase of CPU utilization. Full article
(This article belongs to the Section Computing and Artificial Intelligence)
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9 pages, 2798 KiB  
Article
Nanosheets of CuCo2O4 As a High-Performance Electrocatalyst in Urea Oxidation
by Camila Zequine, Fangzhou Wang, Xianglin Li, Deepa Guragain, S.R. Mishra, K. Siam, P. K. Kahol and Ram K. Gupta
Appl. Sci. 2019, 9(4), 793; https://doi.org/10.3390/app9040793 - 24 Feb 2019
Cited by 30 | Viewed by 5626
Abstract
The urea oxidation reaction (UOR) is a possible solution to solve the world’s energy crisis. Fuel cells have been used in the UOR to generate hydrogen with a lower potential compared to water splitting, decreasing the costs of energy production. Urea is abundantly [...] Read more.
The urea oxidation reaction (UOR) is a possible solution to solve the world’s energy crisis. Fuel cells have been used in the UOR to generate hydrogen with a lower potential compared to water splitting, decreasing the costs of energy production. Urea is abundantly present in agricultural waste and in industrial and human wastewater. Besides generating hydrogen, this reaction provides a pathway to eliminate urea, which is a hazard in the environment and to people’s health. In this study, nanosheets of CuCo2O4 grown on nickel foam were synthesized as an electrocatalyst for urea oxidation to generate hydrogen as a green fuel. The synthesized electrocatalyst was characterized using X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. The electroactivity of CuCo2O4 towards the oxidation of urea in alkaline solution was evaluated using electrochemical measurements. Nanosheets of CuCo2O4 grown on nickel foam required the potential of 1.36 V in 1 M KOH with 0.33 M urea to deliver a current density of 10 mA/cm2. The CuCo2O4 electrode was electrochemically stable for over 15 h of continuous measurements. The high catalytic activities for the hydrogen evolution reaction make the CuCo2O4 electrode a bifunctional catalyst and a promising electroactive material for hydrogen production. The two-electrode electrolyzer demanded a potential of 1.45 V, which was 260 mV less than that for the urea-free counterpart. Our study suggests that the CuCo2O4 electrode can be a promising material as an efficient UOR catalyst for fuel cells to generate hydrogen at a low cost. Full article
(This article belongs to the Special Issue Transition Metal Oxides: The Material of Choice for Heterogeneous Catalysis)
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25 pages, 712 KiB  
Article
Time-Constrained Nature-Inspired Optimization Algorithms for an Efficient Energy Management System in Smart Homes and Buildings
by Ibrar Ullah and Sajjad Hussain
Appl. Sci. 2019, 9(4), 792; https://doi.org/10.3390/app9040792 - 23 Feb 2019
Cited by 33 | Viewed by 5491
Abstract
This paper proposes two bio-inspired heuristic algorithms, the Moth-Flame Optimization (MFO) algorithm and Genetic Algorithm (GA), for an Energy Management System (EMS) in smart homes and buildings. Their performance in terms of energy cost reduction, minimization of the Peak to Average power Ratio [...] Read more.
This paper proposes two bio-inspired heuristic algorithms, the Moth-Flame Optimization (MFO) algorithm and Genetic Algorithm (GA), for an Energy Management System (EMS) in smart homes and buildings. Their performance in terms of energy cost reduction, minimization of the Peak to Average power Ratio (PAR) and end-user discomfort minimization are analysed and discussed. Then, a hybrid version of GA and MFO, named TG-MFO (Time-constrained Genetic-Moth Flame Optimization), is proposed for achieving the aforementioned objectives. TG-MFO not only hybridizes GA and MFO, but also incorporates time constraints for each appliance to achieve maximum end-user comfort. Different algorithms have been proposed in the literature for energy optimization. However, they have increased end-user frustration in terms of increased waiting time for home appliances to be switched ON. The proposed TG-MFO algorithm is specially designed for nearly-zero end-user discomfort due to scheduling of appliances, keeping in view the timespan of individual appliances. Renewable energy sources and battery storage units are also integrated for achieving maximum end-user benefits. For comparison, five bio-inspired heuristic algorithms, i.e., Genetic Algorithm (GA), Ant Colony Optimization (ACO), Cuckoo Search Algorithm (CSA), Firefly Algorithm (FA) and Moth-Flame Optimization (MFO), are used to achieve the aforementioned objectives in the residential sector in comparison with TG-MFO. The simulations through MATLAB show that our proposed algorithm has reduced the energy cost up to 32.25% for a single user and 49.96% for thirty users in a residential sector compared to unscheduled load. Full article
(This article belongs to the Special Issue Smart Home and Energy Management Systems 2019)
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18 pages, 1192 KiB  
Article
Numerical Evaluation of Sample Gathering Solutions for Mobile Robots
by Adrian Burlacu, Marius Kloetzer and Cristian Mahulea
Appl. Sci. 2019, 9(4), 791; https://doi.org/10.3390/app9040791 - 23 Feb 2019
Cited by 4 | Viewed by 3125
Abstract
This paper applies mathematical modeling and solution numerical evaluation to the problem of collecting a set of samples scattered throughout a graph environment and transporting them to a storage facility. A team of identical robots is available, where each robot has a limited [...] Read more.
This paper applies mathematical modeling and solution numerical evaluation to the problem of collecting a set of samples scattered throughout a graph environment and transporting them to a storage facility. A team of identical robots is available, where each robot has a limited amount of energy and it can carry one sample at a time. The graph weights are related to energy and time consumed for moving between adjacent nodes, and thus, the task is transformed to a specific optimal assignment problem. The design of the mathematical model starts from a mixed-integer linear programming problem whose solution yields an optimal movement plan that minimizes the total time for gathering all samples. For reducing the computational complexity of the optimal solution, we develop two sub-optimal relaxations and then we quantitatively compare all the approaches based on extensive numerical simulations. The numerical evaluation yields a decision diagram that can help a user to choose the appropriate method for a given problem instance. Full article
(This article belongs to the Special Issue Advanced Mobile Robotics)
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19 pages, 5148 KiB  
Article
A Theoretical Comparative Study of CO2 Cascade Refrigeration Systems
by Evangelos Bellos and Christos Tzivanidis
Appl. Sci. 2019, 9(4), 790; https://doi.org/10.3390/app9040790 - 23 Feb 2019
Cited by 39 | Viewed by 7751
Abstract
The objective of this work is the comparison of the different cascade refrigeration systems with CO2 in the low-temperature circuit. A total of 18 different cascade refrigeration systems are examined including the CO2/CO2 cascade system. The analysis is performed [...] Read more.
The objective of this work is the comparison of the different cascade refrigeration systems with CO2 in the low-temperature circuit. A total of 18 different cascade refrigeration systems are examined including the CO2/CO2 cascade system. The analysis is performed for four different evaporator temperatures (−35, −25, −15 and −5 °C), while the condenser temperature is ranged from 10 up to 45 °C. The systems are compared energetically, as well as using the total equivalent warming impact (TEWI) for yearly operation at the weather conditions of Athens (Greece). The final results show that all the examined cascade systems are more efficient than the CO2/CO2 cascade system. The natural refrigerants (NH3, R290, R600, R600a and R1270) seem to be the most appropriate choices according to the energy and the TEWI criteria. Moreover, the refrigerant R152a is a promising choice for achieving high performance with a relatively low TEWI. Full article
(This article belongs to the Section Mechanical Engineering)
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15 pages, 4442 KiB  
Article
Performance and Control Strategy of Real-Time Simulation of a Three-Phase Solid-State Transformer
by Jorge Almaguer, Víctor Cárdenas, Jose Espinoza, Alejandro Aganza-Torres and Marcos González
Appl. Sci. 2019, 9(4), 789; https://doi.org/10.3390/app9040789 - 23 Feb 2019
Cited by 10 | Viewed by 3746
Abstract
This paper shows the real-time simulation of a three-stage three-phase solid-state transformer with an Opal OP5607 platform. The simulation model considers the complete electronic full-order circuit for the topology without the use of simplifications, such as average models or equivalent circuits for the [...] Read more.
This paper shows the real-time simulation of a three-stage three-phase solid-state transformer with an Opal OP5607 platform. The simulation model considers the complete electronic full-order circuit for the topology without the use of simplifications, such as average models or equivalent circuits for the coupling transformer and the input and output converters, which may neglect part of the dynamics of interest for the converter design. The simulation is made through an electronic hardware solver (eHS), which can achieve smaller solving times than the regular algorithms, allowing to reach the switching frequency rate for this converters. The simulation model takes the RTE-library which is used for DC-DC converters, with simple arrangements in order to operate with the topology. Full article
(This article belongs to the Section Electrical, Electronics and Communications Engineering)
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9 pages, 1696 KiB  
Article
Enhanced Device Performance of GaInN-Based Green Light-Emitting Diode with Sputtered AlN Buffer Layer
by Seiji Ishimoto, Dong-Pyo Han, Kengo Yamamoto, Ryoya Mano, Satoshi Kamiyama, Tetsuya Takeuchi, Motoaki Iwaya and Isamu Akasaki
Appl. Sci. 2019, 9(4), 788; https://doi.org/10.3390/app9040788 - 23 Feb 2019
Cited by 11 | Viewed by 3611
Abstract
In this study, we compared the device performance of GaInN-based green LEDs grown on c-plane sapphire substrates with a conventional low temperature GaN buffer layer to those with a sputtered-AlN buffer layer. The light output power and leakage current characteristics were significantly [...] Read more.
In this study, we compared the device performance of GaInN-based green LEDs grown on c-plane sapphire substrates with a conventional low temperature GaN buffer layer to those with a sputtered-AlN buffer layer. The light output power and leakage current characteristics were significantly improved by just replacing the buffer layer with a sputtered-AlN layer. To understand the origin of the improvement in performance, the electrical and optical properties were compared by means of electro-reflectance spectroscopy, I–V curves, electroluminescence spectra, L–I curves, and internal quantum efficiencies. From the analysis of the results, we concluded that the improvement is mainly due to the mitigation of strain and reduction of the piezoelectric field in the multiple quantum wells active region. Full article
(This article belongs to the Special Issue Internal Quantum Efficiency of III-Nitride Light-Emitting Diodes)
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15 pages, 6148 KiB  
Article
Correlation of Microstructure and Mechanical Properties of Metal Big Area Additive Manufacturing
by Benjamin Shassere, Andrzej Nycz, Mark W. Noakes, Christopher Masuo and Niyanth Sridharan
Appl. Sci. 2019, 9(4), 787; https://doi.org/10.3390/app9040787 - 23 Feb 2019
Cited by 55 | Viewed by 9080
Abstract
Metal Big Area Additive Manufacturing (MBAAM) is a novel wire-arc additive manufacturing method that uses a correction-based approach developed at the Oak Ridge National Laboratory (ORNL). This approach is an integrated software method that minimizes the dynamic nature of welding and compensates for [...] Read more.
Metal Big Area Additive Manufacturing (MBAAM) is a novel wire-arc additive manufacturing method that uses a correction-based approach developed at the Oak Ridge National Laboratory (ORNL). This approach is an integrated software method that minimizes the dynamic nature of welding and compensates for build height. The MBAAM process is used to fabricate simple geometry thin walled specimens, using a C-Mn steel weld wire, to investigate the scatter in mechanical properties and correlate them to the underlying microstructure. The uni-axial tensile tests show isotropic tensile and yield properties with respect to building directions, although some scatter in elongation is observed. Large scatter is observed in the Charpy Impact tests. The microstructure characterization reveals mostly homogenous ferrite grains with some pearlite, except for some changes in morphology and grain size at the interface between the build and the base plate. The measured properties and microstructure are compared with the toughness and strength values reported in the literature, and a hypothesis is developed to rationalize the differences. Overall, the MBAAM process creates stable, isotropic, and weld-like mechanical properties in the deposit, while achieving a precise geometry obtained through a real-time feedback sensing, closed loop control system. Full article
(This article belongs to the Special Issue Welding of Steels)
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12 pages, 6996 KiB  
Article
Successful Release of Voriconazole and Flavonoids from MAPLE Deposited Bioactive Surfaces
by Irina Negut, Anita Ioana Visan, Camelia Popescu, Rodica Cristescu, Anton Ficai, Alexandru Mihai Grumezescu, Mariana C. Chifiriuc, Ryan D. Boehm, Dina Yamaleyeva, Michael Taylor, Roger J. Narayan and Douglas B. Chrisey
Appl. Sci. 2019, 9(4), 786; https://doi.org/10.3390/app9040786 - 22 Feb 2019
Cited by 6 | Viewed by 3431
Abstract
We explored the potential of biomimetic thin films fabricated by means of matrix-assisted pulsed laser evaporation (MAPLE) for releasing combinations of active substances represented by flavonoids (quercetin dihydrate and resveratrol) and antifungal compounds (amphotericin B and voriconazole) embedded in a polyvinylpyrrolidone biopolymer; the [...] Read more.
We explored the potential of biomimetic thin films fabricated by means of matrix-assisted pulsed laser evaporation (MAPLE) for releasing combinations of active substances represented by flavonoids (quercetin dihydrate and resveratrol) and antifungal compounds (amphotericin B and voriconazole) embedded in a polyvinylpyrrolidone biopolymer; the antifungal activity of the film components was evaluated using in vitro microbiological assays. Thin films were deposited using a pulsed KrF* excimer laser source which were structurally characterized using atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR). High-quality thin films with chemical structures similar to dropcast ones were created using an optimum laser fluence of ~80 mJ/cm2. Bioactive substances were included within the polymer thin films using the MAPLE technique. The results of the in vitro microbiology assay, which utilized a modified disk diffusion approach and were performed using two fungal strains (Candida albicans American Type Culture Collection (ATCC) 90028 and Candida parapsilosis American Type Culture Collection (ATCC) 22019), revealed that voriconazole was released in an active form from the polyvinylpyrrolidone matrix. The results of this study show that the MAPLE-deposited bioactive thin films have a promising potential for use in designing combination products and devices, such as drug delivery devices, and medical device surfaces with antifungal activity. Full article
(This article belongs to the Special Issue New Trends in Bioresorbable Polymers for Biomedical Applications)
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12 pages, 3392 KiB  
Article
Improving the Lot Fabrication Stability and Performance of Silica Optical Films during PECVD
by Yu Zheng, Piaopiao Gao, Zhixin Xiao, Jianying Zhou, Ji’an Duan and Bo Chen
Appl. Sci. 2019, 9(4), 785; https://doi.org/10.3390/app9040785 - 22 Feb 2019
Cited by 6 | Viewed by 2972
Abstract
Silica optical film specifications are determined by their processing capability and their fabrication stability. Here, a statistical process control (SPC) approach usually used in planar lightwave circuits (PLC) is adopted to analyze the stability of the silica optical film fabrication process. Apart from [...] Read more.
Silica optical film specifications are determined by their processing capability and their fabrication stability. Here, a statistical process control (SPC) approach usually used in planar lightwave circuits (PLC) is adopted to analyze the stability of the silica optical film fabrication process. Apart from the raw materials, certain key external factors have to be taken into consideration during the PLC process, such as temperature, relative humidity, process variation and machine aging. The fabrication process can be adjusted according to SPC-based results in real-time, so as to produce high quality silica optical film. By using this method, it is possible to assess the effectiveness of older production lines and extend their production capacity at minimal cost. Full article
(This article belongs to the Special Issue Photonic Integrated Circuits for Optical Communications)
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13 pages, 383 KiB  
Review
Hidden Charge Orders in Low-Dimensional Mott Insulators
by Serena Fazzini and Arianna Montorsi
Appl. Sci. 2019, 9(4), 784; https://doi.org/10.3390/app9040784 - 22 Feb 2019
Cited by 1 | Viewed by 3586
Abstract
The opening of a charge gap driven by interaction is a fingerprint of the transition to a Mott insulating phase. In strongly correlated low-dimensional quantum systems, it can be associated to the ordering of hidden non-local operators. For Fermionic 1D models, in the [...] Read more.
The opening of a charge gap driven by interaction is a fingerprint of the transition to a Mott insulating phase. In strongly correlated low-dimensional quantum systems, it can be associated to the ordering of hidden non-local operators. For Fermionic 1D models, in the presence of spin–charge separation and short-ranged interaction, a bosonization analysis proves that such operators are the parity and/or string charge operators. In fact, a finite fractional non-local parity charge order is also capable of characterizing some two-dimensional Mott insulators, in both the Fermionic and the bosonic cases. When string charge order takes place in 1D, degenerate edge modes with fractional charge appear, peculiar of a topological insulator. In this article, we review the above framework, and we test it to investigate through density-matrix-renormalization-group (DMRG) numerical analysis the robustness of both hidden orders at half-filling in the 1D Fermionic Hubbard model extended with long range density-density interaction. The preliminary results obtained at finite size including several neighbors in the case of dipolar, screened and unscreened repulsive Coulomb interactions, confirm the phase diagram of the standard extended Hubbard model. Besides the trivial Mott phase, the bond ordered and charge density wave insulating phases are also not destroyed by longer ranged interaction, and still manifest hidden non-local orders. Full article
(This article belongs to the Special Issue Metal-Insulator Transitions)
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