Stability of the lower level sets of ICAR functions
- Authors: López, Marco , Rubinov, Alex , Vera De Serio, Virginia
- Date: 2005
- Type: Text , Journal article
- Relation: Numerical Functional Analysis and Optimization Vol. 26, no. 1 (2005), p. 113-127
- Full Text: false
- Reviewed:
- Description: In this paper, we study the stability of the lower level set {x E R++n | f (x) ≤ 0} of a finite valued increasing convex-along-rays (ICAR) function f defined on R++n. In monotonic analysis, ICAR functions play the role of usual convex functions in classical convex analysis. We show that each ICAR function f is locally Lipschitz on int dom f and that the pointwise convergence of a sequence of ICAR functions implies its uniform convergence on each compact subset of R ++n. The latter allows us to establish stability results for ICAR functions in some sense similar to those for convex functions. Copyright © Taylor & Francis, Inc.
- Description: C1
- Description: 2003001419
Preparation of starch-based nanoparticles through high-pressure homogenization and miniemulsion cross-linking: Influence of various process parameters on particle size and stability
- Authors: Shi, Aimin , Li, Dong , Wang, Li Ming , Li, Bingzheng , Adhikari, Benu
- Date: 2010
- Type: Text , Journal article
- Relation: Carbohydrate Polymers Vol. 83, no. 4 (2010), p. 1604-1610
- Full Text: false
- Reviewed:
- Description: A new and convenient synthetic route using high-pressure homogenization combined with water-in-oil (w/o) miniemulsion cross-linking technique was used to prepare sodium trimetaphosphate (STMP)-cross-linked starch nanoparticles. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) revealed that starch nanoparticles had narrow size distribution, good dispersibility and spherical shape. Effect of process parameters (surfactant content, water/oil ratio, starch concentration, homogenization pressure and cycles) on the starch nanoparticle size in miniemulsion was evaluated. We show that there is an optimal surfactant concentration giving rise to smaller starch nanoparticles and better stability. Apart from the water/oil ratio and starch concentration, the homogenization pressure and cycles (passes) also significantly affect the size of starch nanoparticles (p < 0.05). The stability analysis of starch nanoparticles in water for 2 h to 2 days and in temperature ranges of 25-45 °C showed firm structure and good stability. These nanoparticles are expected to be exploited as drug carriers. © 2010 Elsevier Ltd. All rights reserved.
- Description: 2003008433
Spray drying of skim milk mixed with milk permeate : Effect on drying behavior, physicochemical properties, and storage stability of powder
- Authors: Shrestha, A. , Howes, Tony , Adhikari, Benu , Bhandari, Bhesh
- Date: 2008
- Type: Text , Journal article
- Relation: Drying Technology Vol. 26, no. 2 (2008), p. 239-247
- Full Text: false
- Reviewed:
- Description: The possibility of using milk permeate (MP) to lower the protein level of skim milk powder (SMP) in producing powders of 34% and lower protein is explored. Skim milk suspensions with various levels of MP were prepared by mixing SMP and MP powder (MPP) at the ratios of 1: 0, 7: 3, 3: 7, and 0: 1: from 34 to 5.3% protein. The suspensions were dried in a spray dryer with inlet and outlet temperatures of 180 and 80 degrees C, respectively. Increasing permeate concentration in the mixture showed a greater tendency to stickiness manifested by lowered the cyclone recovery of the powder as more powder stuck on the wall of the dryer. Increasing permeate concentration in the resultant powder did not significantly affect the bulk density but led to a reduction in the particle size and also made the powder slight green and yellowish in color. It also found to lower the glass transition temperature (T-g) of the skim milk powder (SMP) and induce crystallization of lactose at lower water activity (a(w) >= 0.328 for SMP: MPP of 3: 7 and 0: 1 compared to a(w) >= 0.0.432 for SMP: MPP of 1: 0 and 3: 7). Addition of MP in SMP lowered the Tg values of the resulting powders. The permeate fraction in spray-dried SMP/MPP mixtures found to lower the critical aw and moisture content, suggesting the SMP mixed with MPP is more likely to become sticky than SMP alone (at 34% protein) when stored at a similar water activity and moisture content.
Trunk muscle electromyographic activity with unstable and unilateral exercises
- Authors: Behm, David , Leonard, Allison , Young, Warren , Bonsey, Andrew , MacKinnon, Scott N.
- Date: 2005
- Type: Text , Journal article
- Relation: Journal of Strength and Conditioning Research Vol. 19, no. 1 (2005), p. 193-201
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- Description: The purpose of this cross-sectional study was to evaluate the effect of unstable and unilateral resistance exercises on trunk muscle activation. Eleven subjects (6 men and 5 women) between 20 and 45 years of age participated. Six trunk exercises, as well as unilateral and bilateral shoulder and chest presses against resistance, were performed on stable (bench) and unstable (Swiss ball) bases. Electromyographic activity of the upper lumbar, lumbosacral erector spinae, and lower-abdominal muscles were monitored. Instability generated greater activation of the lower-abdominal stabilizer musculature (27.9%) with the trunk exercises and all trunk stabilizers (37.7-54.3%) with the chest press. There was no effect of instability on the shoulder press. Unilateral shoulder press produced greater activation of the back stabilizers, and unilateral chest press resulted in higher activation of all trunk stabilizers, when compared with bilateral presses. Regardless of stability, the superman exercise was the most effective trunk-stabilizer exercise for back-stabilizer activation, whereas the side bridge was the optimal exercise for lower-abdominal muscle activation. Thus, the most effective means for trunk strengthening should involve back or abdominal exercises with unstable bases. Furthermore, trunk strengthening can also occur when performing resistance exercises for the limbs, if the exercises are performed unilaterally. © 2005 National Strength & Conditioning Association.
- Description: C1
- Description: 2003001184
A problem of modal control in a linear neutral system
- Authors: Ivanov, Anatoli , Khusainov, D. Ya
- Date: 2001
- Type: Text , Journal article
- Relation: Dynamics of Continuous, Discrete and Impulsive Systems Series B: Application and Algorithm Vol. 8, no. 3 (2001), p. 395-404
- Full Text: false
- Reviewed:
- Description: A problem of modal control is considered for a class of linear multidimensional differential delay systems of neutral type. The control vector is sought in the form that results in a given in advance characteristic equation of the closed system. The problem is completely solved for systems of a special form, the so-called canonical systems. A two-dimensional example is considered in full detail.
Stability of semi-infinite inequality systems involving min-type functions
- Authors: López, Marco , Rubinov, Alex , Vera De Serio, Virginia
- Date: 2005
- Type: Text , Journal article
- Relation: Numerical Functional Analysis and Optimization Vol. 26, no. 1 (2005), p. 81-112
- Full Text: false
- Reviewed:
- Description: We study the stability of semi-infinite inequality systems that arise in monotonic analysis. These systems are defined by certain classes of abstract linear functions. We consider the cone R
- Description: C1
- Description: 2003001420
Full stability of locally optimal solutions in second-order cone programs
- Authors: Mordukhovich, Boris , Outrata, Jiri , Sarabi, Ebrahim
- Date: 2014
- Type: Text , Journal article
- Relation: SIAM Journal on Optimization Vol. 24, no. 4 (2014), p. 1581-1613
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- Description: The paper presents complete characterizations of Lipschitzian full stability of locally optimal solutions to second-order cone programs (SOCPs) expressed entirely in terms of their initial data. These characterizations are obtained via appropriate versions of the quadratic growth and strong second-order sufficient conditions under the corresponding constraint qualifications. We also establish close relationships between full stability of local minimizers for SOCPs and strong regularity of the associated generalized equations at nondegenerate points. Our approach is mainly based on advanced tools of second-order variational analysis and generalized differentiation.
Hydrostatic pressure effects on the structural properties of condensed whey protein/lactose systems
- Authors: Dissanayake, Muditha , Kasapis, Stefan , George, Paul , Adhikari, Benu , Palmer, Martin , Meurer, Barbara
- Date: 2013
- Type: Text , Journal article
- Relation: Food Hydrocolloids Vol. 30, no. 2 (March 2013), p. 632-640
- Full Text: false
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- Description: Hydrostatic pressure effects on whey protein/lactose mixtures were recorded with subsequent analysis of their structural, molecular and glass transition properties in comparison to thermal effects at atmospheric pressure. Experimental techniques used were small deformation dynamic oscillation in shear, modulated differential scanning calorimetry, Fourier transform infrared spectroscopy, and theoretical modelling of glass transition phenomena. Levels of solids ranged from 30 to 80% (w/w) in formulations with a protein/co-solute ratio of four-to-one. Addition of lactose protects the secondary conformation of the protein under application of high hydrostatic pressure. Nevertheless, pressurized protein systems are able to form three-dimensional structures due to the reduction in polymeric free volume and the development of an efficient friction coefficient amongst tightly packed particles. Systems can be seen as developing a "molten globular state", where the structural knots of pressure-treated networks remain in the native conformation but achieve intermolecular cross-linking owing to frictional contact. Furthermore, pressure treated assemblies of condensed whey protein preparations could match the viscoelasticity of the thermally treated counterparts upon cooling below ambient temperatures. That allowed examination of the physical state and morphology of a condensed preparation at 80% solids by the combined framework of reduced variables and free volume theory thus affording derivation of glass transition temperatures for pressurized and atmospheric samples. (C) 2012 Published by Elsevier Ltd.
Effect of gum Arabic on stability of oil-in-water emulsion stabilized by flaxseed and soybean protein
- Authors: Wang, Bo , Wang, Li , Li, Dong , Adhikari, Benu , Shi, John
- Date: 2011
- Type: Text , Journal article
- Relation: Carbohydrate Polymers Vol. 86, no. 1 (2011), p. 343-351
- Full Text: false
- Reviewed:
- Description: The effects of gum Arabic (GA) addition (0-4%, w/w) on stability of oil-in-water emulsion stabilized by flaxseed protein concentrate (FPC) and soybean protein concentrate (SPC) were studied. The result shows that emulsions stabilized by both proteins in the presence of the 2% gum Arabic (w/w) have better stability than its absence, by increasing the emulsion viscosity of the FPC stabilized emulsion and causing competitive adsorption between the GA and SPC layer to give a steric repulsion for the SPC stabilized emulsion, respectively. Then, the influences of ionic strength (0-200 mM NaCl) and temperature (25-95 °C for 20 min) on these emulsions in presence of GA were determined. The GA adsorbed at SPC-stabilized oil-water interface provided stability against NaCl concentration. In presence of GA, the SPC-stabilized emulsions also showed better stability at higher temperatures compared to the FPC-stabilized emulsions due to the denaturation of SPC and competitive adsorption between GA and SPC at higher temperatures. © 2011 Elsevier Ltd All rights reserved.
The effect of dryer inlet and outlet air temperatures and protectant solids on the survival of Lactococcus lactis during spray drying
- Authors: Ghandi, Amir , Powell, Ian , Chen, Xiao Dong , Adhikari, Benu
- Date: 2012
- Type: Text , Journal article
- Relation: Drying Technology Vol. 30, no. 14 (2012), p. 1649-1657
- Full Text: false
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- Description: The influence of spray-drying conditions, inlet air temperature (130 degrees C to 200 degrees C), outlet air temperature (38 degrees C to 65 degrees C), drying medium (air and nitrogen) and milk-derived protectants (10%, 15%, and 25% lactose; 5% and 10% sodium caseinate; 10%, 25%, and 35% lactose: sodium caseinate (Lac: NaCas, 3:1)) on the survival of Lactococcus lactis ssp. cremoris was studied using a laboratory-scale spray dryer. An inlet air temperature of 130 degrees C and 65 degrees C as the outlet air temperature maintained high survival of the bacteria without sacrificing low moisture content. Inlet air temperature, previously considered to have no significant effect, was shown to play an important role in the survival of bacteria during spray drying. A mixture of Lac:NaCas (3: 1) showed a better protective effect on the survival of bacteria than lactose and sodium caseinate individually, and this effect increased with increasing amount of protectant. The results were generalized by substituting whey protein isolate for sodium caseinate. Finally, the positive effect of elimination of oxygen was demonstrated both by replacing air with nitrogen and adding ascorbic acid as an oxygen scavenger to improve survival of the bacteria. Adding an oxygen scavenger would be a better candidate for industrial application considering the potential high cost of manufacturing if nitrogen was used as the atomization and/or drying medium.
- Description: C1
On coderivatives and Lipschitzian properties of the dual pair in optimization
- Authors: López, Marco , Ridolfi, Andrea , Vera De Serio, Virginia
- Date: 2012
- Type: Text , Journal article
- Relation: Nonlinear Analysis, Theory, Methods and Applications Vol. 75, no. 3 (2012), p. 1461-1482
- Full Text: false
- Reviewed:
- Description: In this paper, we apply the concept of coderivative and other tools from the generalized differentiation theory for set-valued mappings to study the stability of the feasible sets of both the primal and the dual problem in infinite-dimensional linear optimization with infinitely many explicit constraints and an additional conic constraint. After providing some specific duality results for our dual pair, we study the Lipschitz-like property of both mappings and also give bounds for the associated Lipschitz moduli. The situation for the dual shows much more involved than the case of the primal problem. © 2011 Elsevier Ltd. All rights reserved.
Microencapsulation of alpha-Amylase by carrying out complex coacervation and drying in a single step using a novel three-fluid nozzle spray drying
- Authors: Jiang, Hao , Zhang, Min , McKnight, Stafford , Adhikari, Benu
- Date: 2013
- Type: Text , Journal article
- Relation: Drying Technology Vol. 31, no. 16 (December 2013 2013), p. 1901-1910
- Full Text: false
- Reviewed:
- Description: The aim of this research was to develop an enzyme encapsulation process in which both the complex coacervation and drying processes are combined into a single step. For this purpose, we used a novel three-fluid nozzle at the atomization step of spray drying. -Amylase as a model enzyme was encapsulated by coacervation in calcium (Ca) alginate and Ca-alginate+chitosan shell matrices and the powder was obtained in a single step through spray drying. The single-step process was compared to carrying out the complex coacervation and drying processes in two steps using freeze drying, in which -amylase was encapsulated by carrying out the complexation process in the above-mentioned shell matrices using the same three-fluid atomizer and collecting the coacervates, which were subsequently freeze dried. The results showed that the microcapsules obtained from the single-step encapsulation process (three-fluid nozzle spray drying) had smaller particle sizes, were less porous, and provided better enzyme stability compared to the microcapsules obtained by carrying out the complexation and drying in two steps and the single-step process was faster. It was observed that the egg-box structure was formed in both types of powder particles; however, the complexation with chitosan partially disrupted the formation of this structure. The three-fluid nozzle-based spray drying is a promising technology in which both the complex coacervation and drying processes can be carried out in a single step.
- Description: C1
Lower semicontinuity of the feasible set mapping of linear systems relative to their domains
- Authors: Daniilidis, Aris , Goberna, Miguel , López, Marco , Lucchetti, Roberto
- Date: 2013
- Type: Text , Journal article
- Relation: Set-Valued and Variational Analysis Vol. 21, no. 1 (2013), p. 67-92
- Relation: http://purl.org/au-research/grants/arc/DP110102011
- Full Text:
- Reviewed:
- Description: This paper deals with stability properties of the feasible set of linear inequality systems having a finite number of variables and an arbitrary number of constraints. Several types of perturbations preserving consistency are considered, affecting respectively, all of the data, the left-hand side data, or the right-hand side coefficients.
Dynamical analysis of neural networks with time-varying delays using the LMI approach
- Authors: Lakshmanan, Shanmugam , Lim, Cheepeng , Bhatti, Asim , Gao, David , Nahavandi, Saeid
- Date: 2015
- Type: Text , Conference paper
- Relation: 22nd International Conference on Neural Information Processing, ICONIP 2015; Istanbul, Turkey; 9th-12th November 2015 Vol. 9491, p. 297-305
- Full Text: false
- Reviewed:
- Description: This study is concerned with the delay-range-dependent stability analysis for neural networks with time-varying delay and Markovian jumping parameters. The time-varying delay is assumed to lie in an interval of lower and upper bounds. The Markovian jumping parameters are introduced in delayed neural networks, which are modeled in a continuous-time along with finite-state Markov chain. Moreover, the sufficient condition is derived in terms of linear matrix inequalities based on appropriate Lyapunov-Krasovskii functionals and stochastic stability theory, which guarantees the globally asymptotic stable condition in the mean square. Finally, a numerical example is provided to validate the effectiveness of the proposed conditions. © Springer International Publishing Switzerland 2015.
A comprehensive method for analyzing the effect of geotextile layers on embankment stability
- Authors: Tolooiyan, Ali , Abustan, Ismail , Selamat, Mohamad , Ghaffari, Sh
- Date: 2009
- Type: Text , Journal article
- Relation: Geotextiles and Geomembranes Vol. 27, no. 5 (2009), p. 399-405
- Full Text: false
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- Description: Commercial software is used widely in slope stability analyses of reinforced embankments. Almost all of these programs consider the tensile strength of geotextiles and soil-geotextile interface friction. However, currently available commercial software generally does not consider the drainage function of nonwoven geotextile reinforcement. In this paper, a reinforced channel embankment reinforced by a nonwoven geotextile is analyzed using two methods. The first method only considers the tensile strength and soil-geotextile interface friction. The second method also considers the drainage function. In both cases, the reinforced embankment is modeled in rapid drawdown condition since this is one of the most important conditions with regard to stability of channel embankments. It is shown that for this type of application, modeling a nonwoven geotextile reinforced embankment using commercial software which neglects the drainage function of the geotextile may be unrealistic.
On Cournot-Nash-Walras equilibria and their computation
- Authors: Outrata, Jiri , Ferris, Michael , Červinka, Michal , Outrata, Michal
- Date: 2016
- Type: Text , Journal article
- Relation: Set-Valued and Variational Analysis Vol. 24, no. 3 (2016), p. 387-402
- Full Text: false
- Reviewed:
- Description: This paper concerns a model of Cournot-Nash-Walras (CNW) equilibrium where the Cournot-Nash concept is used to capture equilibrium of an oligopolistic market with non-cooperative players/firms who share a certain amount of a so-called rare resource needed for their production, and the Walras equilibrium determines the price of that rare resource. We prove the existence of CNW equilibria under reasonable conditions and examine their local stability with respect to small perturbations of problem data. In this way we show the uniqueness of CNW equilibria under mild additional requirements. Finally, we suggest some efficient numerical approaches and compute several instances of an illustrative test example. © 2016, Springer Science+Business Media Dordrecht.
Stability in linear optimization and related topics. A personal tour
- Authors: López, Marco
- Date: 2012
- Type: Text , Journal article
- Relation: TOP Vol. 20, no. 2 (2012), p. 217-244
- Relation: http://purl.org/au-research/grants/arc/DP110102011
- Full Text: false
- Reviewed:
- Description: This paper is a kind of biased survey of the most representative and recent results on stability for the linear optimization problem. Qualitative and quantitative approaches are considered in this survey, and some infinite-dimensional extensions of the main results to more general problems are also included. In particular the paper deals with the lower/upper semicontinuity of the feasible/optimal set mappings, different types of ill-posedness, distance to ill-posedness, Lipschitz properties of these mappings under different types of perturbations, and estimates of the associated Lipschitz bounds.
On Holder continuity of solution maps of parametric primal and dual Ky Fan inequalities
- Authors: Anh, Lam Quoc , Khanh, Phan Quoc , Tam, T. N.
- Date: 2015
- Type: Text , Journal article
- Relation: Top Vol. 23, no. 1 (2015), p. 151-167
- Full Text: false
- Reviewed:
- Description: We consider parametric primal and dual Ky Fan inequalities in metric linear spaces. Sufficient conditions for Holder continuity of solutions are established. Many examples are provided to illustrate the essentialness of the imposed assumptions and advantages of the results over existing ones. As applications, we derive this Holder continuity of solutions for constrained minimization and variational inequalities.
Multi-level supervisory emergency control for operation of remote area microgrid clusters
- Authors: Batool, Munira , Shahnia, Farhad , Islam, Syed
- Date: 2019
- Type: Text , Journal article
- Relation: Journal of Modern Power Systems and Clean Energy Vol. 7, no. 5 (Sep 2019), p. 1210-1228
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- Description: Remote and regional areas are usually supplied by isolated and self-sufficient electricity systems, which are called as microgrids (MGs). To reduce the overall cost of electricity production, MGs rely on non-dispatchable renewable sources. Emergencies such as overloading or excessive generation by renewable sources can result in a substantial voltage or frequency deviation in MGs. This paper presents a supervisory controller for such emergencies. The key idea is to remedy the emergencies by optimal internal or external support. A multi-level controller with soft, intermedial and hard actions is proposed. The soft actions include the adjustment of the droop parameters of the sources and the controlling of the charge/discharge of energy storages. The intermedial action is exchanging power with neighboring MGs, which is highly probable in large remote areas. As the last remedying resort, curtailing loads or renewable sources are assumed as hard actions. The proposed controller employs an optimization technique consisting of certain objectives such as reducing power loss in the tie-lines amongst MGs and the dependency of an MG to other MGs, as well as enhancing the contribution of renewable sources in electricity generation. Minimization of the fuel consumption and emissions of conventional generators, along with frequency and voltage deviation, is the other desired objectives. The performance of the proposal is evaluated by several numerical analyses in MATLAB (R).
Holder error bounds and holder calmness with applications to convex semi-infinite optimization
- Authors: Kruger, Alexander , Lopez, Marco , Yang, Xiaoqi , Zhu, Jiangxing
- Date: 2019
- Type: Text , Journal article
- Relation: Set-Valued and Variational Analysis Vol. 27, no. 4 (Dec 2019), p. 995-1023
- Full Text:
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- Description: Using techniques of variational analysis, necessary and sufficient subdifferential conditions for Holder error bounds are investigated and some new estimates for the corresponding modulus are obtained. As an application, we consider the setting of convex semi-infinite optimization and give a characterization of the Holder calmness of the argmin mapping in terms of the level set mapping (with respect to the objective function) and a special supremum function. We also estimate the Holder calmness modulus of the argmin mapping in the framework of linear programming.