Post Audit Analysis of a Groundwater Level Prediction Model in Developed Semiconfined Aquifer System

This paper assesses groundwater recharge under conditions of long-term groundwater pumping at the Ravnik pumping site in Croatia and analyses the groundwater level prediction model used in prior aquifer modelling. The results of model calibration revealed a very low net infiltration rate at the start of the pumping site’s operation. As the operation continued, the net infiltration rate slowly increased, while the percentage of infiltrated rainfall scaled up with increasing pumping rates. The predicted recharge of the covering aquitard amounts approximately 14–15 % of the mean annual precipitation. The aquifer recharge takes place from aquitard by seepage. A subsequent simulation of the pumping site’s operation was performed for the 9 years period on the assumption that the pumping rates and the groundwater recharge would be the same as those recorded during the final calibration years. Results show that the post audit measured levels correspond relatively well to the predicted levels and that increasing of the pumping rate causes changes in the water budget in advantage of net groundwater recharge as a consequence of spreading recharge area outside of previous model boundaries.     

On quantifying nonthermal effects on the lethality of pressure-assisted heat preservation processes

Direct experimental identification and quantification of the pressure contribution to a pressure-assisted sterilization process efficacy is difficult. However, dynamic kinetic models of thermal inactivation can be used to assess the lethality of a purely thermal process having the same temperature profile. Thus, a pressure-assisted process' temperature record can be used to generate a corresponding purely thermal survival curve with parameters determined in conventional heating experiments. Comparison of the actual final survival ratio with that calculated for the purely thermal process would reveal whether the hydrostatic pressure had synergistic or antagonistic effect on bacterial spores survival. The effect would be manifested in the number of log cycles subtracted or added to the survival ratio, and in the length of time at the holding temperature needed to produce the final survival ratio of the combined process. A set of combined treatments would reveal how the temperature and pressure profiles affect the pressure's influence on the process' lethality to either vegetative cells or spores. The need to withdraw samples during the thermal and combined processes would be avoided if the thermal survival parameters could be calculated by the "three endpoints method," which does not require the entire survival curve determination. Currently however, this method is limited to thermal inactivation patterns characterized by up to 3 survival parameters, the Weibull-Log logistic (WeLL) model, for example.     

The Arrhenius equation revisited

The Arrhenius equation has been widely used as a model of the temperature effect on the rate of chemical reactions and biological processes in foods. Since the model requires that the rate increase monotonically with temperature, its applicability to enzymatic reactions and microbial growth, which have optimal temperature, is obviously limited. This is also true for microbial inactivation and chemical reactions that only start at an elevated temperature, and for complex processes and reactions that do not follow fixed order kinetics, that is, where the isothermal rate constant, however defined, is a function of both temperature and time. The linearity of the Arrhenius plot, that is, Ln[k(T)] vs. 1/T where T is in °K has been traditionally considered evidence of the model's validity. Consequently, the slope of the plot has been used to calculate the reaction or processes' "energy of activation," usually without independent verification. Many experimental and simulated rate constant vs. temperature relationships that yield linear Arrhenius plots can also be described by the simpler exponential model Ln[k(T)/k(T(reference))] = c(T-T(reference)). The use of the exponential model or similar empirical alternative would eliminate the confusing temperature axis inversion, the unnecessary compression of the temperature scale, and the need for kinetic assumptions that are hard to affirm in food systems. It would also eliminate the reference to the Universal gas constant in systems where a "mole" cannot be clearly identified. Unless proven otherwise by independent experiments, one cannot dismiss the notion that the apparent linearity of the Arrhenius plot in many food systems is due to a mathematical property of the model's equation rather than to the existence of a temperature independent "energy of activation." If T+273.16°C in the Arrhenius model's equation is replaced by T+b, where the numerical value of the arbitrary constant b is substantially larger than T and T(reference), the plot of Ln k(T) vs. 1/(T+b) will always appear almost perfectly linear. Both the modified Arrhenius model version having the arbitrary constant b, Ln[k(T)/k(T(reference)) = a[1/ (T(reference)+b)-1/ (T+b)], and the exponential model can faithfully describe temperature dependencies traditionally described by the Arrhenius equation without the assumption of a temperature independent "energy of activation." This is demonstrated mathematically and with computer simulations, and with reprocessed classical kinetic data and published food results.     

Derivation of a control oriented low order model of the dynamics of an infrared oven for the continuous drying of a thin sheet of material

A model consisting of three partial non-linear differential equations for describing the humidity and temperature of a thin sheet of material and of the temperature of the air flow as a function of time and position in an infrared dryer was reduced to a model more adaptable to direct digital control. To begin with the original model was discretized along the length of the dryer and then linearized. Models of orders ranging from 12 to 72 were analyzed for controllability and observability. Using Moore's method, the models thus obtained were further reduced to a controllable state space model of order 5 that produced satisfactory results and for which stability was preserved. Simulated open loop responses of the reduced model to discrete perturbations in emitter electrical power, inlet humidity and velocity of the web, produced satisfactory dynamic and steady-state responses when compared to responses of the original model subjected to similar perturbations. The steady-state responses showed absolute errors for humidity and temperature of the web less than 1.3% [g water/100 g] and 2.2°C, respectively.     

Floating-impedance realisation using a dual operational-mirrored amplifier

A new realisation for the synthesis of floating impedances?inductor or FDNR/FDNC?is described. The circuit only needs a dual operational amplifier whose power lines are set in the supply-current sensing technique.     

Parent and child stress and symptoms: An integrative analysis.

This study assessed major and daily stressful life events and psychological symptoms in a sample of young adolescents and their parents. The relation between major life events and symptoms was mediated by daily stressors for parents and their young adolescent children. Children's emotional and behavioral problems were associated with fathers' psychological symptoms but not with mothers' symptoms. Both mothers' and fathers' symptoms were associated with their sons' daily stressors, but girls' daily stressors were related only to their mothers' symptoms. Mothers' symptoms were associated with their husbands' daily hassles in families of young adolescent boys, and both parents' symptoms were associated with their spouses' hassles in families of adolescent girls. Highlights the importance of studying stress processes between individuals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Happiness versus sadness as a determinant of thought confidence in persuasion: A self-validation analysis.

The present research introduces a new mechanism by which emotion can affect evaluation. On the basis of the self-validation hypothesis (R. E. Petty, P. Bri?ol, & Z. L. Tormala, see record 2002-12575-003), the authors predicted and found that emotion can influence evaluative judgments by affecting the confidence people have in their thoughts to a persuasive message. In each study, participants first read a strong or weak persuasive communication. After listing their thoughts about the message, participants were induced to feel happy or sad. Relative to sad participants, those put in a happy state reported more thought confidence. As a consequence, the effect of argument quality on attitudes was greater for happy than for sad participants. These self-validation effects generalized across different emotion inductions, different persuasion topics, and different measures of thought confidence. In one study, happy and sad conditions each differed from a neutral affect control. Most important, these metacognitive effects of emotion only occurred under high elaboration conditions. In contrast, individuals with relatively low motivation to think showed a main effect of emotion on attitudes, regardless of argument quality. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Overt head movements and persuasion: A self-validation analysis.

The authors report 3 experiments that examine a new mechanism by which overt head movements can affect attitude change. In each experiment, participants were induced to either nod or to shake their heads while listening to a persuasive message. When the message arguments were strong, nodding produced more persuasion than shaking. When the arguments were weak, the reverse occurred. These effects were most pronounced when elaboration was high. These findings are consistent with the "self-validation" hypothesis that postulates that head movements either enhance (nodding) or undermine (shaking) confidence in one's thoughts about the message. In a 4th experiment, the authors extended this result to another overt behavior (writing with the dominant or nondominant hand) and a different attitude domain (self-esteem). (PsycINFO Database Record (c) 2010 APA, all rights reserved)