We analyze risk-neutral multiobjective optimal control problems, governed by Volterra integral equations with random inputs, and subject to expectation-type final/pure state constraints and mixed ...pointwise control-state constraints. Moreover, controls are unbounded, and inclusion-form pure state as well as control-state constraints are given by measurable set-valued mappings, whose images are nonempty closed subsets of infinite dimensional spaces. With such constraints, the multiplier corresponding to pure state constraints belongs to the dual space of the Banach space-valued continuous functions. We set up a decomposition result for this dual, and develop a Lagrange multiplier theorem for an abstract multi-criteria optimization model, in which a Robinson-type constraint qualification is applied. Then, making use of the obtained outcomes, exploiting higher integrability and regularity of the random field control/state variables, and employing Banach space-valued integration techniques, we derive Fritz-John necessary optimality conditions, with integrable functions and (countably additive) measures singular with respect to the Lebesgue measure as multipliers, for local weak Pareto solutions of studied problems.
Recent theoretical conceptualizations of student engagement have raised questions about how to measure student engagement and how engagement varies not only across schools, but also within school and ...within classrooms. The authors build on existing research on student behavioral engagement and extend this research to emphasize a continuum of disengagement, active engagement, and passive engagement. They review common approaches to measuring engagement and highlight areas where new theoretical conceptualizations of engagement require new approaches to measurement. The authors analyze how student behavioral engagement changed depending on the context and demonstrate the need of a finer scale of engagement. They find there was not a uniform association of higher behavioral engagement and student interaction with peers, but it was the interaction with other students and the teacher that was predictive of increased engagement. Their work suggests that disaggregating behavioral engagement into disengagement, active engagement, and passive engagement has important research and conceptual implications.
Lab-on-a-chip technology is an emerging field evolving from the recent advances of micro- and nanotechnologies. The technology allows the integration of various components into a single microdevice. ...Microfluidics, the science and engineering of fluid flow in microscale, is the enabling underlying concept for lab-on-a-chip technology. The present paper reviews the design, fabrication and characterization of drug delivery systems based on this amazing technology. The systems are categorized and discussed according to the scales at which the drug is administered. Starting with the fundamentals on scaling laws of mass transfer and basic fabrication techniques, the paper reviews and discusses drug delivery devices for cellular, tissue and organism levels. At the cellular level, a concentration gradient generator integrated with a cell culture platform is the main drug delivery scheme of interest. At the tissue level, the synthesis of smart particles as drug carriers using lab-on-a-chip technology is the main focus of recent developments. At the organism level, microneedles and implantable devices with fluid-handling components are the main drug delivery systems. For drug delivery to a small organism that can fit into a microchip, devices similar to those of cellular level can be used.
Display omitted
This article is concerned with multiobjective optimal control problems, driven by evolution equations, and involving implicit control constraints and mixed pointwise control-state constraints in ...infinite dimensional separable Banach spaces. We consider bounded controls and inclusion-type mixed pointwise constraints, which are given in terms of measurable set-valued mappings whose images are closed convex sets with nonempty interior. In this case, the multiplier associated with mixed constraints is an element of the dual space of the Banach space-valued essentially bounded functions. Exploiting the combination of the Ioffe-Levin decomposition theorem for this dual and a Lagrange multiplier theorem obtained for an abstract multi-criteria optimization framework, we set up Fritz-John necessary optimality conditions, in the presence of integrable functions and singular measures as multipliers, for local weak Pareto solutions of the problems under investigation. Moreover, we give some conditions under which the multipliers are regular. An example of application of the main result is also provided to show the existence of a nontrivial singular measure.
Activated carbon produced from agricultural products and wastes has been applied widely to remove pollutants in the field of waste water treatment. However, the cost of this adsorbent depends so much ...on the raw material sources. Therefore, the approach of producing activated carbon from agricultural waste is strongly recommended due to economic advantages and environmental protection. One of the potential feed-stocks for the activated carbon production is cashew nut shell (CNS) waste which could reduce the negative impacts to the environment from the cashew nut processing industry and simultaneously enhance the values of the related products. This study focused on evaluating the influences of variable factors, such as activation temperature and time, on the properties of the activated carbon obtained from CNS. Methylene blue (MB) adsorption was applied to understand the adsorption mechanism of the products. The results show that increasing the activation temperature led to a rise in the adsorption capacity of the activated carbon within the temperature range of 800 to 850 °C. Otherwise, the values were reduced when the temperature was greater than 850 °C and this was related to the thermal decomposition of carbon. The adsorption capacity also increased when the activation time was changed from 30 min to 50 min. However, in the activation time range from 50 to 70 min, there was a reduction of the adsorption capacity of CNS-based activated carbon. The results also show that the MB adsorption of the activated carbon occurred with one-site-occupancy in the first layer and then layer-by-layer adsorption formation.
Activated carbon produced from agricultural products and wastes has been applied widely to remove pollutants in the field of waste water treatment.
•Modelling maintenance data of electrical transformers given by Electricity of France (EDF).•Analyze the Arithmetic Reduction of Age having Weibull failure distribution.•Develop probability ...distributions of effective ages and inter-failure times.•Highlight the convergence property.•Propose three age-based imperfect preventive maintenance policies.
The paper considers repairable systems under imperfect repair. The failure rate of a new system is assumed to follow a Weibull distribution and the repair efficiency is characterized by a Kijima type II virtual age model named Arithmetic Reduction of Age with infinite memory. An analytical approach to obtain the distribution of the inter-failure times is presented. The existence of a stationary regime is highlighted and the limiting distributions are explicitly derived. In this context, an optimal age-based preventive maintenance policy can be implemented. Three approaches are proposed, considering a static, a dynamic or a failure limit policy. Numerical simulations are presented to illustrate the policies.
We investigate a multiobjective optimal control problem, governed by a strongly continuous semigroup operator in an infinite dimensional separable Banach space, and with final-state constraints, ...pointwise pure state constraints and a mixed pointwise control-state constraint. Basing on necessary optimality conditions obtained for an abstract multiobjective optimization framework, we establish a second-order Lagrange multiplier rule, of Fritz-John type, for local weak Pareto solutions of the problem under study. As a consequence of the main result, we also derive a multiplier rule for a multiobjective optimal control model driven by a bilinear system being affine-linear in the control, and with an objective function of continuous quadratic form.
•A low-cost approach for sample concentration on a microfluidic paper-based platform.•Fast establishment of ion depletion zone at an integrated nanoporous junction.•Fast sample concentration through ...a combination of transport phenomena including ion concentration polarization, electrophoresis and electrosmosis.
We report a low-cost approach for sample concentration in a microfluidic paper-based analytical device using ion concentration polarization. This device platform can attain liquid sample filling by capillary suction through the microporous paper and ion selective transport through a nanoporous polymer matrix under DC electric field. The device demonstrated a fast depletion of fluorescent dye samples and can serve as an effective microfluidic concentrator of fluorescent dye with 60-fold concentration enhancement achieved within 200s. The device fabrication is simply based on paper cutting and lamination without the need of lithography and printing of hydrophobic material such as wax. The lamination approach presented in this paper has the potential to be transferred to a large-scale production of paper-based analytical devices.
We consider multiobjective optimal control problems for semilinear parabolic systems subject to pointwise state constraints, integral state-control constraints and pointwise state-control ...constraints. In addition, the data of the problems need not be twice Fréchet differentiable. Employing the second-order directional derivative (in the sense of Demyanov-Pevnyi) for the involved functions, we establish necessary optimality conditions, via second-order Lagrange multiplier rules of Fritz-John type, for local weak Pareto solutions of the problems.
The paper considers complex industrial systems with incomplete maintenance history. A corrective maintenance is performed after the occurrence of a failure and its efficiency is assumed to be ...imperfect. In maintenance analysis, the databases are not necessarily complete. Specifically, the observations are assumed to be window-censored. This situation arises relatively frequently after the purchase of a second-hand unit or in the absence of maintenance record during the burn-in phase. The joint assessment of the wear-out of the system and the maintenance efficiency is investigated under missing data. A review along with extensions of statistical inference procedures from an observation window are proposed in the case of perfect and minimal repair using the renewal and Poisson theories, respectively. Virtual age models are employed to model imperfect repair. In this framework, new estimation procedures are developed. In particular, maximum likelihood estimation methods are derived for the most classical virtual age models. The benefits of the new estimation procedures are highlighted by numerical simulations and an application to a real data set.
•New estimation procedures for window-censored observations and imperfect repair.•Extensions of inference methods for perfect and minimal repair with missing data.•Overview of maximum likelihood method with complete and incomplete observations.•Benefits of the new procedures highlighted by simulation studies and real application.
PDF
