On a Kelvin-Voigt Viscoelastic Wave Equation with Strong Delay

An initial-boundary value problem for a viscoelastic wave equation subject to a strong time-localized delay in a Kelvin & Voigt-type material law is considered. Transforming the equation to an abstract Cauchy problem on the extended phase space, a global well-posedness theory is established using the operator semigroup theory both in Sobolev-valued $C^{0}$- and BV-spaces. Under appropriate assumptions on the coefficients, a global exponential decay rate is obtained and the stability region in the parameter space is further explored using the Lyapunov's indirect method. The singular limit $\tau \to 0$ is further studied with the aid of the energy method. Finally, a numerical example from a real-world application in biomechanics is presented.Comment: 34 pages, 4 figures, 1 set of Matlab code

RETAIL OLIGOPOLY POWER AND FLUID MILK PRICES IN BOSTON

This paper assesses the independent and joint impacts of oligopoly power of market intermediaries and the Northeast Dairy Compact (NEDC) on fluid milk prices in Boston. Empirical results reveal that price increases due to oligopoly power far outweighed those caused by the NEDC by more than 10 times. In fact, markups are estimated at approximately 33% of the retail milk price, translating into approximately $1/gallon overcharge at 2002 milk prices averaging around$3/gallon.Demand and Price Analysis,

A Supermarket-Level Analysis of Demand for Breakfast Cereals: A Random Coefficients Approach

This paper applies the BLP approach to the demand for ready-to-eat cereals (RTECs) at the supermarket-chain level in Boston using IRI monthly data. The Random Coefficient Model is used to estimate the demand for 37 brands of RTECs at the leading supermarkets in the Boston area. The empirical results provide a wealth of consumer behavior information, including own- and cross-price elasticites for 37 brands of RTECs at four leading supermarkets in Boston. The demand for RTECs is generally price elastic (ranging between -3 and -8). Consumers respond positively and strongly to promotion, negatively and strongly to price, calories and fiber, and weakly to sugar content. Income has a strong interactive effect with product characteristics and thus is a useful variable for market segmentation. In comparison, the results with the more commonly used Logit model indicate significantly lower price elasticities, provide a limited window on consumer behavior, and yield predicted brand and supermarket market shares that are quite divergent from observed values.Demand and Price Analysis,

RETAIL OLIGOPOLY POWER, DAIRY COMPACT, AND BOSTON MILK PRICES

This paper assesses the impacts of the Northeast Dairy Compact (NEDC) and retail oligopoly power on fluid milk prices in Boston. Empirical results reveal that price increases due to oligopoly power outweighed those caused by the NEDC by nearly seven times. In fact, markups are estimated at approximately 25% of the retail milk price, translating into approximately a little less than $0.75/gallon. We also estimated that only around two-thirds of the raw milk price changes were passed forward to consumers. This helps explain why consumer prices have come down only little after elimination of the NEDC. In fact, the new milk income loss contract program, which basically provides partial price subsidies to farmers, has contributed to low raw milk prices that have generated substantial benefits to milk processors and retailers, modest benefits to farmers and consumers, all at the expense of taxpayers.Industrial Organization, Livestock Production/Industries,

Simultaneous wireless information and power transfer based on generalized triangular decomposition

In this paper, a new approach, based on the generalized triangular decomposition (GTD), is proposed for simultaneous wireless information and power transfer (SWIPT) in the spatial domain for a point-to-point multiple-input multiple-output (MIMO) system. The proposed approach takes advantage of the GTD structure to allow the transmitter to use the strongest eigenchannel jointly for energy harvesting and information exchange while these transmissions can be separated at the receiver. The optimal structure of the GTD that maximizes the total information rate constrained by a given power allocation and a required amount of energy harvesting is derived. An algorithm is developed that minimizes the total transmitted power for given information rate and energy harvesting constraints with a limited total power at the transmitter. Both theoretical and simulation results show that our proposed GTD based SWIPT outperforms singular value decomposition (SVD) based SWIPT. This is due to the flexibility introduced by the GTD to increase the energy harvested via interstream interference

Effect of Initial Conditions on the Scalar Decay in Grid Turbulence at Low Rλ

Decaying grid turbulence is considered at low Reynolds number (Rλ ~ 50) for different initial conditions. Three different grid geometries are used. Heat is injected via a mandoline at a distance of 1.5 M from the grid. The amount of heating is such that temperature may be treated as a passive scalar. A small contraction (1.36:1) is added at a distance of 11M downstream of the grid. The power-law exponents for the scalar variance are compared with those for the turbulent kinetic energy. These exponents depend on the grid geometry. For the isotropic dissipation rate 〈χ〉iso, the power-law exponent agrees with that inferred from the temperature variance transport equation. Restricting the range of validity of the decay law affects the magnitudes of the origin and decay exponent. Secondorder temperature structure functions collapse when the normalization is based on the local temperature variance and the Corrsin microscale but the asymptotic form of this collapse depends on the initial conditions

Contribution à l’étude de l’huile essentielle de Dipcadi serotinum (l.) Medik du Maroc

Dipcadi serotinum (L.) Medik, est une plante de la famille des Hyacinthaceae, elle est largement utilisée comme réchauffant et aussi pour combattre la jaunisse. Cette plante trouve une large utilisation par la population de la région côtière du Maroc. À notre connaissance l’huile essentielle de cette espèce n’a jamais été étudiée ni chimiquement ni biologiquement. Dans ce contexte, nous avons mené une étude comparative de l’huile essentielle extraite de la partie aérienne et la partie souterraine. Les résultats obtenus pour les rendements et la composition chimique de l’huile essentielle des deux parties étudiés montrent des différences considérables.Mots-clés : Dipcadi serotinum (L.) Medik, huile essentielle, composition chimique, médecine traditionnelle, Maroc.Contribution to the study of the essential oil of Dipcadi serotinum (l.) Medik of MoroccoDipcadi serotinum (L.) Medik, is a plant of the Hyacinthaceae’s family, it is widely used as warming and also to combat the jaundice. This plant is widespread use by the population of the coastal region of Morocco. To our knowledge the essential oil of this species has never been studied or chemically or biologically. In this context, we conducted a comparative study of the essential oil extracted from the aerial part and underground part. The results for yield and chemical composition of essential oil from both sides studied showed significant differences.Keywords : Dipcadi serotinum (L.) Medik, essential oil, chemical composition, traditional medicine, Morocco

Fuzzy Logic Controller of Five Levels Active Power Filter

AbstractThis paper presents five-level inverter as a shunt active power filter (SAPF) to compensate reactive power and suppresses harmonics drawn from a diode rectifier supplying RL load under distorted voltage conditions. The harmonic current extraction is based on the use of self tuning filter (STF) and fuzzy logic controller employed to control harmonic current and inverter DC voltage. The aim of the present work is to obtain a perfect compensation by extracting accurate harmonic currents to improve the performances of the five-levels active power filters.The proposed scheme is validated by computer simulation using MATLAB Fuzzy Logic Toolbox in order to show the effectiveness and ability of this method. The results have demonstrated that the proposed shunt active power filter with STF and Fuzzy Logic Controller (FLC) have produced a sinusoidal supply current with low harmonic distortion and in phase with the line voltage

IMPACTS DE LA CONCENTRATION ET DU TYPE DE SEL SUR LE POTENTIEL GERMINATIF ET LA PRODUCTION DE BIOMASSE CHEZ L’ORGE (HORDEUM VULGARE)

La présente étude a pour objectif de déterminer l’effet de la salinité représentée par la concentration et le type de sels sur la germination et la croissance de l’orge. Les sels utilisés sont : NaCl, KCl, MgSO4 et Na2SO4avec les doses 6, 12 et 18g/lcombinées avec des doses 0, 0.5 et 1g/l d'un amendement calcique représenté par CaCl2 et CaSO4.Les paramètres étudiés sont le taux de germination, et la production de la biomasse qui comporte la partie aérienne et la partie racinaire. Les résultats obtenus montrent que l’augmentation de la salinité est néfaste sur les paramètres cités :diminution du taux de germination, réduction de la croissance de la partie aérienne et racinaire et une chute de la production de la matière fraiche.Cependant l’amendement calcique a montré un effet remarquable sur le végétal par rapport aux traitements non amendés en allégeant l’effet inhibiteur des sels. Concernant l’effet du type de sel, il semble que les sels KCl, MgSO4 et Na2SO4 apparaissent moins toxiques que NaCl. This study is designed to determine the effect of salinity concentration and the type of salts on the germination and growth of barley. The salts used are: NaCl, KCl, MgSO4 and Na2SO4 with doses 6, 12 and 18 g/l combined with doses 0, 0.5 and 1 g/l of calcium amendment represented by CaCl2 and CaSO4. The parameters studied are the germination rate, and production of biomass that has the air and the root part. The results obtained show that the increase in salinity is harmful on the quoted parameters: decrease in germination rate, reduction in the growth of the aerial and root part and a fall of the production of the fresh material. However the calcium amendment has shown a remarkable effect on the plant compared to treatments not amended by easing the inhibitory effect of salts. Concerning the effect of the type of salt, it seems that NaCl appear less toxic than KCl, MgSO4 and Na2SO4 salts