Applied Sciences

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EISSN : 2076-3417
Current Publisher: MDPI (10.3390)
Total articles ≅ 17,583
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Ali Alorabi, Fahad Alharthi, Mohamed Azizi, Nabil Al-Zaqri, Adel El-Marghany, Khaled Abdelshafeek
Published: 24 October 2020
by MDPI
Applied Sciences, Volume 10; doi:10.3390/app10217450

Abstract:
In this work, the widely-abundant, cheap, wild plant Lavandula pubescens Decne was evaluated as an adsorbent for removing Pb(II) ions from wastewater. The chemical composition of the plant was partially isolated and characterized by the corresponding techniques, including gas chromatography–mass spectrometry, gas liquid chromatography, and FTIR spectroscopy. The adsorption capacity of the dried plant material for Pb(II) ions increased with increasing contact time, initial ion concentration, and temperature, while it decreased with increasing adsorbent dosage. The optimum condition for Pb(II) adsorption was determined as 550 mg/L initial metal concentration, pH ≤ 7, and 90 min of contact. The best fit for Pb(II) adsorption isotherms was the linear form of the Freundlich model; however, the maximum capacity indicated by Langmuir was 91.32 mg/g. The experimental data fit better the pseudo-second-order kinetic model (R2 = 0.969), suggesting chemisorption process. Thermodynamic data revealed an endothermic, nonspontaneous, and adsorption process favored at higher concentrations.
Tae-Il Kim, Dong-Hyun Lim, Hyun-Jeong Lee, Seong-Min Park, Yoon-Jeong Kim, Hee-Chul Choi, Jong-Ho Park, Sam-Churl Kim, Kwang-Seok Ki, Vijayakumar Mayakrishnan
Published: 23 October 2020
by MDPI
Applied Sciences, Volume 10; doi:10.3390/app10217442

Abstract:
This study aimed to determine the effects of replacing corn with hydroponically sprouted barley (HSB) in Holstein heifer feed on growth performance and blood metabolites. For this purpose, the barley was prepared with hydroponic sprouting under optimized conditions, and its chemical composition was analyzed on a dry matter (DM) basis. A total of 30 Holstein heifers that were 7 months old with an average body weight of 212.60 ± 55.00 kg were used in a completely randomized design comprising 10 repetitions and three groups over a period of 11 months. Dietary treatments included control (CON), basal diet (corn meal-based diets), and trail diets, in which 10% and 30% HSB gradually replaced corn meal. The growth performance and biochemical indices were analyzed every month. Results showed that the HSB diet increased chemical compositions compared with the control diets on a DM basis. In addition, diets with up to 30% HSB did not show any negative effects on the growth performance (body weight, height at withers, and height at rump) or selected blood metabolites of heifers compared with the CON diet. In conclusion, the use of HSB instead of corn meal did not lead to any adverse effects on growth performance or biochemical indices; therefore, HSB can be used as an alternative dietary source for raising Holstein heifers.
Han-Saem Kim, Chang-Guk Sun, Mingi Kim, Hyung-Ik Cho, Moon-Gyo Lee
Published: 23 October 2020
by MDPI
Applied Sciences, Volume 10; doi:10.3390/app10217443

Abstract:
Soil and rock characteristics are primarily affected by geological, geotechnical, and terrain variation with spatial uncertainty. Earthquake-induced hazards are also strongly influenced by site-specific seismic site effects associated with subsurface strata and soil stiffness. For reliable mapping of soil and seismic zonation, qualification and normalization of spatial uncertainties is required; this can be achieved by interactive refinement of a geospatial database with remote sensing-based and geotechnical information. In this study, geotechnical spatial information and zonation were developed while verifying database integrity, spatial clustering, optimization of geospatial interpolation, and mapping site response characteristics. This framework was applied to Daejeon, South Korea, to consider spatially biased terrain, geological, and geotechnical properties in an inland urban area. For developing the spatially best-matched geometry with remote sensing data at high spatial resolution, the hybrid model blended with two outlier detection methods was proposed and applied for geotechnical datasets. A multiscale grid subdivided by hot spot-based clusters was generated using the optimized geospatial interpolation model. A principal component analysis-based unified zonation map identified vulnerable districts in the central old downtown area based on the integration of the optimized geoprocessing framework. Performance of the geospatial mapping and seismic zonation was discussed with digital elevation model, geological map.
Nicolo' Stevanato, Lorenzo Rinaldi, Stefano Pistolese, Sergio Luis Balderrama Subieta, Sylvain Quoilin, Emanuela Colombo
Published: 23 October 2020
by MDPI
Applied Sciences, Volume 10; doi:10.3390/app10217445

Abstract:
Energy system models for off-grid systems usually tend to focus solely on the provision of electricity for powering simple appliances, thus neglecting more energy-intensive and critical needs, such as water heating. The adoption of a Multi-Energy System (MES) perspective would allow us not only to provide comprehensive solutions addressing all types of energy demand, but also to exploit synergies between the electric and thermal sectors. To this end, we expand an existing open-source micro-grid optimization model with a complementary thermal model. Results show how the latter achieves optimal solutions that are otherwise restricted, allowing for a reduction in the Levelized Cost of Energy (LCOE) of 59% compared to a conventional microgrid, and an increase of reliance on renewable sources of 70%.
Steen Nielsen, Alexandros Stefanakis
Published: 23 October 2020
by MDPI
Applied Sciences, Volume 10; doi:10.3390/app10217446

Abstract:
Sludge treatment reed beds (STRBs) are an established sludge treatment technology with multiple environmental and economic advantages in dewatering sludge generated during domestic wastewater treatment. However, little is reported regarding their appropriateness and efficiency for the treatment of sludge produced during industrial wastewater treatment and from water works. These sludge types may have significantly different quality characteristics than typical domestic sludge and may contain constituents that could affect their dewaterability. Therefore, the dewatering of these industrial sludge types is usually tested in small-scale pilot STRBs before the construction of full-scale systems. This paper presents and summarizes the state-of-the-art experience from existing pilot and full-scale STRB systems from various countries and climates treating sludge from various industrial sources, evaluates the suitability and the advantages of this sustainable treatment technology, and proposes the required dimensioning for efficient full-scale STRB operation and performance.
Gregory Guarda, Apostolos Pesyridis, Ashish Sam
Published: 23 October 2020
by MDPI
Applied Sciences, Volume 10; doi:10.3390/app10217452

Abstract:
Stringent emission regulations and increased demand for improved fuel economy have called for advanced turbo technologies in automotive engines. The use of turbochargers on smaller engines is one such concept, but they are limited by a time delay in reaching the required boost during transient operation. The amount of turbocharger lag plays a key role in the driver’s perceived quality of a passenger vehicle’s engine response. This paper investigates an alternative method to the conventional design of a turbocharger turbine to improve the transient response of a passenger vehicle. The investigation utilises the Ford Eco-Boost 1.6 L petrol engine, an established production engine, equipped with a turbocharger of similar performance to the GT1548 produced by Honeywell. The commercially available Ricardo WAVE was used to model the engine. Comparing the steady-state performance showed that the axial turbine provides higher efficiencies at all operating conditions of an engine. The transient case demonstrated an improved transient response at all operating conditions of the engine. The study concluded that, by designing a similar sized axial turbine, the mass moment of inertia can be reduced by 12.64% and transient response can be improved on average by 11.76%, with a maximum of 21.05% improvement. This study provides encouragement for the wider application of this turbine type to vehicles operating on dynamic driving cycles such as passenger vehicles, light commercial vehicles, and certain off-road applications.
Bae-Guen Kim, Seong-Hyeon Kang, Chan Park, Hyun-Woo Jeong, Youngjin Lee
Published: 23 October 2020
by MDPI
Applied Sciences, Volume 10; doi:10.3390/app10217455

Abstract:
Although conventional denoising filters have been developed for noise reduction from digital images, these filters simultaneously cause blurring in the images. To address this problem, we proposed the fast non-local means (FNLM) denoising algorithm which would preserve the edge information of objects better than conventional denoising filters. In this study, we obtained thoracic computed tomography (CT) images from a male adult mesh (MASH) phantom modeled by computer and a five-year-old phantom to perform both the simulation study and the practical study. Subsequently, the FNLM denoising algorithm and conventional denoising filters, such as the Gaussian, median, and Wiener filters, were applied to the MASH phantom image adding Gaussian noise with a standard deviation of 0.002 and practical CT images. Finally, the results were compared quantitatively in terms of the coefficient of variation (COV), contrast-to-noise ratio (CNR), peak signal-to-noise ratio (PSNR), and correlation coefficient (CC). The results showed that the FNLM denoising algorithm was more efficient than the conventional denoising filters. In conclusion, through the simulation study and the practical study, this study demonstrated the feasibility of the FNLM denoising algorithm for noise reduction from thoracic CT images.
Seungjin Yoo, Jin Jang, Jai-Kyung Lee, Jong-Won Park
Published: 23 October 2020
by MDPI
Applied Sciences, Volume 10; doi:10.3390/app10217459

Abstract:
In order to verify the reliability of drive components for industrial robots, component-level life tests must be accompanied by a system-level life test using actual robots in which predefined robot motions are repeated throughout the test. To properly verify the durability of drive components through a system-level life test, it is important to design test modes so that the required test time is the same for all joint drive components of the robot, and it is necessary to design test modes with a high acceleration factor so as to shorten the required test time as much as possible. To solve this problem, the present research proposes a method for designing robot motions that makes the accelerated life test time for all the drive components of the robot equal. In particular, we solve a dynamic based motion optimization problem for an industrial 6-DoF (degrees-of-freedom) robot that minimizes the AM-GM (arithmetic mean to geometric mean) ratio of the acceleration factors of each joint. The results show that -continuous test modes with the same acceleration factor, which is inversely proportional to the cycle time of the robot motion, can be derived.accelerated life testing; acceleration factor; reliability; dynamic motion planning; optimal robot motion
Jesús Sierra-García, Matilde Santos
Published: 23 October 2020
by MDPI
Applied Sciences, Volume 10; doi:10.3390/app10217462

Abstract:
In this work, a pitch controller of a wind turbine (WT) inspired by reinforcement learning (RL) is designed and implemented. The control system consists of a state estimator, a reward strategy, a policy table, and a policy update algorithm. Novel reward strategies related to the energy deviation from the rated power are defined. They are designed to improve the efficiency of the WT. Two new categories of reward strategies are proposed: “only positive” (O-P) and “positive-negative” (P-N) rewards. The relationship of these categories with the exploration-exploitation dilemma, the use of ϵ-greedy methods and the learning convergence are also introduced and linked to the WT control problem. In addition, an extensive analysis of the influence of the different rewards in the controller performance and in the learning speed is carried out. The controller is compared with a proportional-integral-derivative (PID) regulator for the same small wind turbine, obtaining better results. The simulations show how the P-N rewards improve the performance of the controller, stabilize the output power around the rated power, and reduce the error over time.
Zhen Li, Changgen Peng, Weijie Tan, Liangrong Li
Published: 23 October 2020
by MDPI
Applied Sciences, Volume 10; doi:10.3390/app10217469

Abstract:
To ensure the security and privacy of digital image when its transmitting online or storing in the cloud, we proposed a novel chaos based image encryption scheme by using randomly DNA encode and plaintext related permutation. In our scheme, we first randomly encode plain image into a nucleotide sequence under the control by the piecewise linear chaotic map(PWLCM). After that, the plaintext related permutation would be done under the control sequence which generated by hyper chaotic Lorenz system (HCLS). Next, we make diffusion processing with key DNA sequence which is generated by another PWLCM system and also encoded randomly. Finally, we decode DNA sequence into cipher image matrix. In addition, we used many common security analysis methods to test our scheme, and the result compared with other works. The tests and comparison results are shown that our proposed image cryptosystem has excellent security performance to ensure the digital image security on communication.
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