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arXiv 2025年

作者： Biazetto, Paulo H.F. de Andrade, Gustavo A. Oliveira, Tiago Roux Krstic, Miroslav Post-graduate Program in Automation and Systems Engineering Federal University of Santa Catarina Florianópolis88040-370 Brazil Department of Automation and Systems Engineering Federal University of Santa Catarina Florianópolis88040-370 Brazil Department of Electronics and Telecommunication Engineering State University of Rio de Janeiro Rio de Janeiro20550-900 Brazil Department of Mechanical and Aerospace Engineering University of California San DiegoCA92093-0411 United States

This paper presents the design and analysis of an extremum seeking (ES) controller for scalar static maps in the context of infinite-dimensional dynamics governed by the 1D Euler-Bernoulli (EB) beam Partial Differential Equation (PDE). The beam is actuated at one end (using position and moment actuators). The map’s input is the displacement at the beam’s uncontrolled end, which is subject to a sliding boundary condition. Notably, ES for this class of PDEs remains unexplored in the existing literature. To compensate for PDE actuation dynamics, we employ a boundary control law via a backstepping transformation and averaging-based estimates for the gradient and Hessian of the static map to be optimized. This compensation controller leverages a Schrödinger equation representation of the EB beam and adapts existing backstepping designs to stabilize the beam. Using the semigroup and averaging theory in infinite dimensions, we prove local exponential convergence to a small neighborhood of the unknown optimal point. Finally, simulations illustrate the effectiveness of the design in optimizing the unknown static map. Copyright © 2025, The Authors. All rights reserved.

关键词： Schrodinger equation

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Effect of low temperature and period of storage on the quality of Garlic Seeds (Allium sativum L) 1

Effect of low temperature and period of storage on the quali...

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1st International Conference on mechanical Electronic and Biosystem engineering, MEBSE 2018

作者： Nurmalia, N. Purwanto, Y.A. Sobir, S. Sulassih, S. Naibaho, N. Post Graduate Program of Postharvest Technology Department of Mechanical and Biosystem Engineering Bogor Agricultural University Indonesia Center of Tropical Horticulture Studies Bogor Agricultural University Indonesia Department of Agronomy and Horticulture Bogor Agricultural University Indonesia

The aim the study was to analyze the effect of temperature storage of garlic seeds including weight loss, sprouting and damage during the storage period. The samples of Garlic seeds are local varieties, cv. Lumbu Hijau and cv. Lumbu Kuning were collected from the farmers in Temanggung Regency. The experiments were set at two different temperature conditions, i.e. 5°C and room temperature (29-31°C) as a control. The relative humidity (RH) of storage conditions was 50-70% for cold storage and 70-80% for storage in room temperature. The amout of sampel used was about 47-68 tubers (500 g) for cv. Lumbu Hijau and around 24-32 tubers (500 gr) for cv. Lumbu Kuning, were placed in cold storage at different temperatures and in dark. The period of storage was design for 5 months. All experiments were carried out in three replications. The results showed that the decrease in weight loss for garlic stored at storage temperatures of 5°C and room temperature were 10.48 and 7.46 % for cv. Lumbu Hijau and 15.03 and 11.38 % cv. Lumbu Kuning, respectively. The higest sprouting percentage was found for those seeds garlic cv. Lumbu Kuning at 5°C, i. e, 22.22 %. The highest percentage of damage after 5 months of storage was found in the seeds of garlic cv. Lumbu Hijau stored at room temperature were 2.30 % and cv. Lumbu Kuning at 5°C were 19.04 %. © Published under licence by IOP Publishing Ltd.

关键词： Cold storage

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Solution of Helmholtz eigenvalue problems with non-regular domains using the direct interpolation technique

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Partial Differential Equations in Applied Mathematics 2025年 14卷

作者： Carlos Friedrich Loeffler Luciano de Oliveira Castro Lara Hercules de Melo Barcelos João Paulo Barbosa Mechanical Engineering Post-Graduate Program Federal University of Espírito Santo UFES CT Av. Fernando Ferrari 540-Bairro Goiabeiras 29075-910 Vitória ES Brazil National Institute of Metrology Quality and Technology INMETRO CEP 25250-020 Duque de Caxias RJ Brazil Federal Institute of Espírito Santo IFES Campus São Mateus Rodovia BR 101 Norte Km 58 Litorâneo 29932540 São Mateus ES Brazil

This work aims to evaluate the performance of the Direct Interpolation Boundary Element Method solving Helmholtz problems that present no regular geometric shapes. Using the radial basis functions, the Direct Interpolation Method approximates the non-self-adjoint kernel of the domain integral equations, which appear in many partial differential equations of mathematics, physics, and engineering. Modeling the Helmholtz Equation, the Direct Interpolation Method approximates the inertia term by a sequence of radial basis functions. The technique has been used successfully in Poisson, Diffusive-advective, and Helmholtz problems, considering regular geometries and taking analytical solutions as a reference for performance evaluation. This paper evaluates the effects of the slenderness of the domain and the introduction of cuts on the boundary regarding the accuracy. Reference solutions are generated through Finite Element Method simulations using fine meshes.

关键词： Boundary elements method Helmholtz’s equation Eigenvalues problems Irregular geometric conformation

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Effect of Method and Duration of Curing on the Compressive Strength of the Lime-Fly Ash Geopolymer Concrete

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Journal of Physics: Conference Series 2020年第1期1594卷

作者： Andi Arham Adam Sri Nur Akifa Atur P.N. Siregar Mustofa Department of Civil Engineering Tadulako University Post-Graduate Program Tadulako University Department of Mechanical Engineering Tadulako University

The use of lime to produce ambient cured Geopolymer concrete is one of a practical solution to avoid heat curing in the production of geopolymer concrete. The addition of lime in the geopolymer system will add another hardened mechanism, i.e. hydration in addition to condensation-polymerisation. This research aims to determine the influence of air and water curing on the strength of geopolymer concrete which uses class F fly ash and lime as raw materials. The geopolymer concrete was produced by varying the activator (sodium silicate and sodium hydroxide) with the variation of the activator to binder ratio of 0.45, 0.50, 0.55, and 0.60. Five per cent of the fly ash was replaced by slaked lime and the water added to the mix to maintain the ratio of water to solid (activator + binder) to 0.32. The test specimens were 100 mm dia x 200 mm height cylinder. Water-immersion curing was performed for 7, 14, and 21 days and the compressive strength test was done at 28 days. The results show that there is a difference in the curing process between the geopolymer concrete and the normal concrete. In the geopolymer concrete, there is a decrease in compressive strength if soaked for seven days and recovered with the increase in the age of immersion. Whereas for normal concrete, the compressive strength continues to increase with increasing age of immersion.

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Wear behavior of dental glass-ceramics: a scoping review on the damage of opposing tooth enamel surfaces

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Biotribology 2020年 21卷

作者： Souza, Júlio C.M. Silva, Cristina S. Caramês, João Henriques, Bruno Novaes de Oliveira, Antonio P. Silva, Filipe S. Gomes, José R. Center for MicroElectroMechanical Systems (CMEMS-UMINHO) University of Minho Campus Azurém Guimarães 4800-058 Portugal University Institute of Heal Sciences (IUCS) CESPU Gandra PRD Portugal School of Dentistry Universidade de Lisboa Lisboa Portugal Post-Graduate Program in Mechanical Engineering (POSMEC) Dept. of Mechanical Engineering (EMC) Federal University of Santa Catarina (UFSC) Florianópolis 88040-900 SC Brazil Laboratory of Glass-Ceramic Materials (VITROCER) Dept. of Mechanical Engineering (EMC) Federal University of Santa Catarina (UFSC) Florianópolis SC Brazil

The main aim of this study was to perform a scoping review on the wear behaviour of recent dental glass-ceramics and its influence on the damage of opposing tooth enamel surfaces. Relevant in vivo and in vitro studies reported significant damage on enamel surfaces after friction against current glass-ceramics and therefore different parameters have been studied such as the glass-ceramic type, wear set up, environment, and surface treatment. The opposing enamel loss in volume, weight, or vertical measurement shown by previous studies is significantly higher when compared to enamel-by-enamel wear values. In fact, high values of hardness and elastic modulus of glass-ceramics combined with rough surfaces can result in detrimental effects on the tooth enamel surfaces. Restorative dental materials must withstand masticatory loads in combination with aesthetic benefits and high biocompatibility. Nevertheless, elastic modulus, hardness, and roughness of glass-ceramics should be adjusted to decrease the damage on tooth enamel surfaces. © 2020 Elsevier Ltd

关键词： Friction Glass-ceramics Restorative dental materials Wear

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Unsteady magnetohydrodynamic channel flow with hall and ion-slip effects: The integral transform solution procedure

Unsteady magnetohydrodynamic channel flow with hall and ion-...

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作者： Da Silva, Bruno N.M. Assad, Gustavo E. De Lima, João A. Post-Graduate Program of Mechanical Engineering UFRN Natal-RN Brazil Federal Institute of Technology IF/PB João Pessoa-PB Brazil Renewable Energy Engineering Department UFPB CEAR João Pessoa-PB Brazil

This paper deals with the generalized integral transform solution procedure to the unsteady magneto-convection problem of an electrically conducting Newtonian fluid within a parallel-plate channel, in which Hall and ion-slip effects are taken into account. It is considered that the magnetic Reynolds number is small, i.e., the flow-induced magnetic fields are not strong enough to modify the applied transversal magnetic field. To cover a broader range of problems, temperature-dependent transport properties, time-dependent pressure gradient, inflow perpendicular to the plates (porous plates), and Couette flow are also considered in the mathematical formulation. Results are illustrated and compared to the main numerical results from the literature for the related velocity and temperature potentials as function of the main governing parameters, namely, Hartmann, suction/injection, transport properties, and electron and ion-slip parameters. In order to illustrate the consistency of the Generalized Integral Transform Technique (GITT) and its use for benchmarking purposes in the magneto fluid dynamics area, convergence analyses are carried out for the main potentials. © 2018 by Begell House, Inc.

关键词： Channel flow

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Performance improvement of palm oil foaming agent concentrates as fire extinguishment materials in peatlands

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IOP Conference Series: Earth and Environmental Science 2020年第1期460卷 012026-012026页

作者： M Rivai E Hambali A Suryani G Pramuhadi P Subekti Surfactant and Bioenergy Research Center IPB University Indonesia Department of Agroindustrial Technology IPB University Indonesia Department of Mechanical and Biosystem Engineering IPB University Indonesia Post Graduate Student Study Program of Agroindustrial Technology IPB University Indonesia Department of Mechanical Engineering Pasir Pengaraian University Indonesia

Foaming agent concentrate made from palm oil produced as a fire extinguishing material in peatlands at a laboratory-scale test were able to extinguish a fire within 3.16 to 4.49 hours. Fire extinguishing ability of this foaming agent concentrate resulted in a lower solution use and shorter extinguishing time than water. However, when compared to commercial products, fire extinguishing time was still longer although the amount of solution needed to extinguish the fire was lower. Therefore, it was necessary to improve the formula to produce a foaming agent concentrate that was able to extinguish the fire in a shorter time with a lower amount of fire extinguishing solution. This study aims to improve the performance of palm oil foaming agent concentrate on extinguishing the fire in peatlands. Efforts to improve the performance were made by reformulation and the addition of chemical fire retardants. Results showed that the addition of fire retardant reduced foaming ability, increased surface tension, lowered viscosity, lowered contact angle, and reduced fire extinguishing time to about 13.08-69.21%.

关键词： Improved formulation palm oil foaming agent concentrate fire extinguisher reduction of extinguishing time

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The effects of magnesium sulphate addition into foaming agents resulted from palm oil fatty acid saponification in the performance of peat fire suppression

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IOP Conference Series: Earth and Environmental Science 2020年第1期460卷

作者： P Subekti E Hambali A Suryani P Suryadarma B H Saharjo M Rivai Post Graduate Student Study Program Agroindustrial Technology IPB University Bogor Indonesia Study Program of Mechanical Engineering Pasir Pengaraian University Regency of Rokan Hulu Riau Indonesia Department of Agroindustrial Technology IPB University Bogor Indonesia Surfactant and Bioenergy Research Center IPB University Bogor Indonesia Forest Fire Laboratory Division of Forest Protection Department of Silviculture IPB University Bogor Indonesia

The utilization of foaming agents resulted from the saponification of palm oil fatty acids as foam concentrate on peat fire suppression leads to less water use and a shorter time compared to the use of peat water only. The development of foaming agents for a peat fire extinguisher, including the addition of 0.2% magnesium sulfate (MgSO4), was further conducted in order to improve the performance of the liquid foam. This study aims to determine the performance of the developed foaming agent (FAP-MS) applied in peat fire suppression. In order to assess the performance of FAP-MS, two controls namely palm fatty acid-based foaming agent without the addition of magnesium sulfate (FAP) and peat water with no mixture of foaming agents were used. Results showed that the durability of foam produced from the peat water solution mixed with FAP-MS was lower than the foam produced from the peat water solution mixed with FAP. The addition of FAP-MS into peat water solution was found to reduce the use of water by 27% and the addition of FAP reduced it further by 35%. However, compared to peat water with no foaming agent addition, FAP-MS and FAP additions were able to suppression peat fires faster by 79% and 65%, respectively.

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Effect of low temperature and period of storage on the quality of Garlic Seeds (Allium sativum L)

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IOP Conference Series: Materials Science and engineering 2019年第1期557卷

作者： Nurmalia Y A Purwanto Sobir Sulassih N Naibaho Post Graduate Program of Postharvest Technology Department of Mechanical and Biosystem Engineering Bogor Agricultural University. Center of Tropical Horticulture Studies Bogor Agricultural University Department of Agronomy and Horticulture Bogor Agricultural University

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Comparative Study of the Corrosion and Cavitation Resistance of HVOF and HVAF FeCrMnSiNi and FeCrMnSiB Coatings

Comparative Study of the Corrosion and Cavitation Resistance...

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International Thermal Spray Conference and Exposition, ITSC 2017

作者： Silveira, L.L. Pukasiewicz, A.G.M. Björttund, S. Nylén, P. Zara, A.J. Post-graduate Program in Mechanical Engineering Federal University of Technology - Parana Ponta Grossa PR Brazil University West Trollhättan Sweden State University of Ponta Grossa Ponta Grossa PR Brazil

ISBN: (纸本)9781510858220

Cavitation and corrosion on hydrodynamic components and systems reduces the operational efficiency. The use of wear resistant coatings have been studied as a solution to the problem of corrosion and cavitation in the industrial environment. Thermal spray processes are recognized as excellent technique to deposit coatings. The high velocity oxy-fuel process (HVOF) can produce high density and bond strength coatings. High velocity air-fuel process (HVAF) is an alternative process, shown to be superior regarding corrosion protection and production costs. HVAF can deposit coating with shorter dwell time and lower temperature, producing coating with lower oxide content This paper presents the use of HVOF and HVAF process to deposit FeCrMnSiNi and FeCrMnSiB coatings, studying the resistance against corrosion and cavitation in comparison to 316L HVOF coating. Microstructure was analyzed by XRD, microscopic means and mechanical testing. Cavitation and corrosion behavior of the coatings were also studied comparatively. HVAF coatings presented lower porosity and oxide levels, as well as higher hardness values, compared with the coatings deposited by HVOF process. The HVAF process presented better cavitation resistance than HVOF coatings. The FeCrMnSiNi HVAF coating had the best corrosion protection performance between the developed alloys. © Copyright 2017 by DVS Media GmbH. All rights reserved.

关键词： Corrosion resistance

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