J. Perić

University of Split, Spalato, Splitsko-Dalmatinska, Croatia

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Publications (42)65.66 Total impact

  • Rabia Bibi · Josip Pečarić · Jurica Perić
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    ABSTRACT: In this paper we give refinements of converse Jensen's inequality as well as of the Hermite-Hadamard inequality on time scales. We give mean value theorems and investigate logarithmic and exponential convexity of the linear functionals related to the obtained refinements. We also give several examples which illustrate possible applications for our results.
    No preview · Article · Sep 2015 · Journal of Mathematical Inequalities
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    ABSTRACT: The removal of lead and zinc from a binary solution by fixed bed depths (40, 80 and 120 mm) of a natural zeolite was examined at a flow rate of 1 mL/min. The results obtained were fitted to the Bed Depth Service Time (BDST) model and the parameters of the model (q and k) were used to design a column system for flow rates of 2 and 3 mL/min at a bed depth of 80 mm. The experimental results were in excellent agreement with those predicted and experimental breakthrough curves for the binary systems were obtained. This approach facilitates the design of effective binary column processes without additional experimentation. Two major design parameters, the Empty Bed Contact Time (EBCT) and the zeolite usage rate, were calculated. The highest EBCT value of 13.56 min represents the optimal conditions for the binary (Pb+Zn) solution.
    No preview · Article · Mar 2015 · Clay Minerals
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    A. Matković · Josip Pečarić · Jurica Perić
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    ABSTRACT: A refinement of the Jessen-Mercer inequality is obtained and shown to be an improvement of the upper bound for the Jessen's difference given in [12]. Also a generalization of the Jessen-Mercer inequality for convex functions on convex hulls in ℝk is given and demonstrated to be an improvement of the inequalities obtained in [3]. An elegant method of producing n-exponentially convex and exponentially convex functions is applied using the Jessen-Mercer differences. Lagrange and Cauchy mean value type theorems are proved and shown to be useful in studying Stolarsky type means defined by using the Jessen-Mercer differences.
    Full-text · Article · Jan 2015 · Journal of Mathematical Inequalities
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    Josip Pečarić · Jurica Perić
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    ABSTRACT: In this paper we prove generalizations and improvements of Lah-Ribarič and related inequalities for convex functions on convex hulls in ℝ k and, analogously, for convex functions on k -simplices in ℝ k . We also verify that one of them is a generalization and an improvement of the Hermite-Hadamard inequality for simplices.
    Preview · Article · Jul 2014 · Mathematical Inequalities and Applications
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    Jadranka Mićić · Josip Pečarić · Jurica Perić
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    ABSTRACT: In this paper converses of a generalized Jensen’s inequality for a continuous field of self-adjoint operators, a unital field of positive linear mappings and real-valued continuous convex functions are studied. New refined converses are presented by using the Mond-Pečarić method improvement. Obtained results are applied to refine selected inequalities with power functions. MSC: 47A63, 47A64.
    Full-text · Article · Dec 2013 · Journal of Inequalities and Applications
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    ABSTRACT: This paper presents the prediction of breakthrough curves for the fixed bed column based on batch studies. Batch equilibrium studies of lead removal on natural zeolite clinoptilolite have been performed. The obtained experimental data have been tested according to the Langmuir and the Freundlich isotherm, and their parameters have been calculated. These parameters and the Mass Transfer Model have been used to predict theoretical breakthrough curves. Theoretical breakthrough curves have been compared with the experimental ones and good agreement has been observed. This indicates that the Mass Transfer Model is applicable for prediction of breakthrough curves from batch studies. The overall mass transfer coefficient has been calculated from column experiments. This value allows for calculation of the height of the mass transfer zone as a very important parameter necessary for column design.
    No preview · Article · Mar 2013 · Chemical and Biochemical Engineering Quarterly
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    ABSTRACT: The removal of Pb and Zn ions from binary aqueous solutions on fixed bed of natural clinoptilolite has been examined. Experiments were performed with different bed depths by using Pb + Zn solutions of the same total molar concentration but with different molar ratios of Pb/Zn. The breakthrough capacity of zeolite increases with bed depth due to longer contact times and higher numbers of mass transfer units. The capacity does not depend on the Pb/Zn ratio at H = 4 cm, while at H = 12 cm it slightly increases at higher Pb/Zn ratios. The results from service cycles have shown displacement of Zn ions bound on zeolite with Pb ions from the feeding solution due to the difference in selectivity of zeolite toward examined ions, which has been confirmed by results from regeneration cycles. This effect is more evident at higher bed depths. Column method examinations allow many service and regeneration cycles without a decrease in capacity or exhaustion of ion exchange ability of clinoptilolite. The Thomas model has provided satisfied agreement with experimental points and enables calculation of exhaustion capacity which is in agreement with experimentally obtained capacities for all examined experiments.
    No preview · Article · Feb 2013 · Microporous and Mesoporous Materials
  • Josip Pečarić · Jurica Perić
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    ABSTRACT: The purpose of this paper is twofold. The first is to give a brief account of the results preceding the main results from S. Simić [J. Math. Anal. Appl. 343, No. 1, 414–419 (2008; Zbl 1138.26008); Appl. Math. Lett. 22, No. 8, 1262–1265 (2009; Zbl 1173.26308)]. The second is to give generalizations and improvements of these results.
    No preview · Article · Dec 2012 · Journal of Mathematical Inequalities
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    ABSTRACT: The aim of this paper is to give improvements of various forms of the Hermite- Hadamard inequality, namely, that of Fejér, Lupaş, Brenner-Alzer, Beesack-Pečarić. It is interesting that these improvements also imply the Hammer-Bullen inequality which deals with a comparison of the left-hand and the right-hand side of the Hermite-Hadamard inequality. These improvements are given in terms of positive linear functionals. Obtained results are used in constructing a new family of exponentially convex functions.
    No preview · Article · Oct 2012 · Mathematical Inequalities and Applications
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    Josip Pečarić · Jurica Perić
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    ABSTRACT: Improvements of the Giaccardi and the Petrović inequality are given. The notion of n-exponentially convex functions is introduced. An elegant method of producing n-exponentially convex and exponentially convex functions is applied using the Giaccardi and the Petrović differences. Cauchy mean value theorems are proved and shown to be useful in studying Stolarsky type means defined using the Giaccardi and the Petrović differences.
    Preview · Article · Jun 2012 · Annals of the University of Craiova
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    ABSTRACT: We give a survey on the converse Jensen inequality and we show that several recently published inequalities are simple consequences of certain long time known results. We also give a new refinement of the converse Jensen inequality as well as improvements of some related results.
    No preview · Article · Feb 2012 · Applied Mathematics and Computation
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    Jadranka Mićić · Josip Pečarić · Jurica Perić
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    ABSTRACT: We give an extension of the refined Jensen's operator inequality for n-tuples of self-adjoint operators, unital n-tuples of positive linear mappings and real valued continuous convex functions with conditions on the spectra of the operators. We also study the order among quasi-arithmetic means under similar conditions.
    Full-text · Article · Jan 2012 · Annals of Functional Analysis
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    ABSTRACT: We use Skorokhod’s embedding theorem to give a new proof of a converse to Jensen’s inequality.
    No preview · Article · Jan 2012 · Rocky Mountain Journal of Mathematics
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    ABSTRACT: The effect of zeolite bed depth on lead removal from aqueous solutions by the column method has been examined. The results indicate that the increase of bed depth delays the breakthrough point and exhaustion point, and increases the contact time of the zeolite – lead solution, and the height of the mass transfer zone, hz. The increase of the bed depth lowers the effect of axial dispersion on the mass transfer process. In order to predict the time necessary for exceeding the defined effluent concentration for a constant bed depth, the bed depth service time (BDST) approach has been used. Experimentally obtained breakthrough curves for the flow rate of 1 ml/min were used to derive the BDST approach equations. These equations were successfully used for modelling of the system for flow rates of 2 and 3 ml/min. The BDST equations have yielded modelled linear equations used for calculation of hz. The increase of the flow rate increases hz, which indicates that the zeolite–solution contact time is not sufficient. This may be attributed to the affect of axial dispersion on mass transfer on the solid-liquid interface.
    No preview · Article · Sep 2009 · Separation Science and Technology
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    ABSTRACT: The column method using a fixed bed of zeolite clinoptilolite was applied to remove lead and zinc ions from binary metal ions solutions. The raw zeolite sample used in this study was obtained from the Vranjska Banja deposit (Serbia) and contained more than 80% of clinoptilolite. The breakthrough curves have an S-shape for the total as well as for the single metal ions in binary solution. Lead and zinc ions bind simultaneously on the zeolite bed, and as the service cycle progresses lead ions displace a great portion of bound zinc. During the regeneration cycle, the quantity of lead desorbed is =15 times higher than the quantity of zinc, which means that mostly lead ions were bound on the zeolite. Breakthrough curves have been interpreted quantitatively by means of the Michaels method, and the results calculated have been compared with the results for single metal ions solutions.
    Preview · Article · Dec 2008 · Studies in surface science and catalysis
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    ABSTRACT: The removal of lead ions from aqueous solutions by means of a fixed bed of natural zeolite clinoptilolite has been investigated. Isothermal column experiments were performed under a constant inlet concentration and bed depth, and different flow rates. The capacities of the breakthrough and exhaustion points do not change significantly with the increase of the flow rate, while the time needed to reach breakthrough is significantly shorter. To determine the kinetic constants, the equation by Yoon and Nelson was applied to the experimental results. The rate proportionality constant KYN increases and the time τ decreases with the increase of the lead solution flow. Based on these parameters the modelled breakthrough curves have been obtained, and they are in agreement with the corresponding experimental data. The parameters of the Yoon–Nelson model have been successfully used for scaling up the bed depth of the examined system, and a satisfactory agreement of experimental and predicted breakthrough curves has been obtained.
    Preview · Article · Oct 2007 · Microporous and Mesoporous Materials
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    ABSTRACT: The kinetics of zinc and lead ions removal by modified zeolite-clinoptilolite has been investigated. The rate of the ion exchange process for lead ions is faster than for zinc ions, as well as the time needed to reach the equilibrium. The ion exchange capacity of zeolite of lead ions is doubly higher than that of zinc ions. Diffusion models according to the Vermeulen's approximation, the parabolic diffusion model and the homogeneous diffusion model have been tested with the experimental data of ion exchange for zinc and lead. For both systems examined, the best fit of the models proposed with the experimental data was shown by the Vermeulen's approximation and the homogeneous diffusion model with t-->t(infinity). The diffusion coefficients are calculated from kinetic models of lead ions they are of the order of 10(-6)cm(2)/min, constant for all examined initial concentrations and not dependent on time. The diffusion coefficients in the system of zinc ions is of the order of 10(-8)cm(2)/min, also independent of initial concentrations, but decreasing with time from the beginning of ion exchange to the equilibrium.
    Full-text · Article · Sep 2006 · Journal of Hazardous Materials
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    ABSTRACT: The kinetics of uptake of zinc ions from aqueous solutions by natural zeolitic tuff has been investigated. Batch experiments at constant temperature and hydrodynamic conditions have been performed. A decrease in the initial zinc concentration in aqueous solutions prolongs the time needed for equilibrium. Various kinetic models including the film-diffusion model, the surface diffusion model and the heterogeneous diffusion model have been tested for the description of the experimental results of zinc concentration in the solution over time. Diffusion through the film and diffusion through the surface of the particle could be the rate limiting steps at the initial reaction time. However, the heterogeneous diffusion model seems to be the best model providing a satisfactory fitting of the experimental results from the beginning of the process to the point of equilibrium, particularly at lower initial zinc concentrations.
    Full-text · Article · Jun 2006 · Journal of Environmental Management
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    ABSTRACT: The aim of this investigation is removal of lead ions from aqueous solutions using the column method with more successive service and regeneration cycles. The experiments were performed at constant temperature and dimensions of column and fixed bed of zeolite, with variation of zeolite particle sizes and flows through the bed, concentrations of lead solutions and the regenerate. Eight service and regeneration cycles were performed without changes of the breakthrough and exhaustion capacity. The highest effectiveness of the column performance has been attained for the zeolite particle size of 0.6–0.8 mm, at the initial concentration of 212.5 mg Pb/L and the flow rate of 2 mL/min. At these experimental conditions, the optimal values of the empty bed contact time and high of the mass transfer zone have been achieved.
    Full-text · Article · May 2006 · Separation and Purification Technology
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    ABSTRACT: An uptake of zinc (Zn), copper (Cu), and lead (Pb) from aqueous solutions by ion exchange on natural zeolitic tuff has been studied. The Croatian zeolite clinoptilolite from the Donje Jesenje deposit has been used as a natural ion exchanger. The efficiency of removal is higher for Pb and Cu than for Zn ions. Measured concentrations of Si in the liquid phase identify the detachment of the aluminosilicate structure during ion exchange in the presence of H(+) and OH(-) ions. The adsorption isotherm equations; Langmuir-Freundlich, Redlich-Petersen, Toth, Dubinin-Radushkevich, modified Dubinin-Radushkevich, and Lineweawer-Burk were derived from the basic empirical equations, and used for calculation of ion exchange parameters. The best fitting of experimental results to the proposed isotherms was observed in models that assume that ionic species bind first at energetically most favorable sites, with multi-layer adsorption taking place subsequently.
    Full-text · Article · May 2004 · Water Research

Publication Stats

872 Citations
65.66 Total Impact Points

Institutions

  • 1996-2015
    • University of Split
      • • Faculty of Chemistry and Technology
      • • Department of Mathematics
      Spalato, Splitsko-Dalmatinska, Croatia
  • 1997-2013
    • University of Zagreb
      • • Faculty of Mechanical Engineering and Naval Architecture (FSB)
      • • Faculty of Veterinary Medicine (VEF)
      • • Department of General Pathology and Pathological Morphology
      Zagrabia, Grad Zagreb, Croatia