Optimal simple monetary policy rules and welfare in a DSGE Model for Hungary

We explore the properties of welfare-maximizing monetary policy in a medium-scale DSGE model for Hungary. In order to make our results operational from a policymaker’s perspective, we approximate the optimal policy rule with a set of simple rules reacting only to observable variables. Our results suggest that “science of monetary policy” that is found robust in simple models, holds in this medium-scaled setting as well. That is, the welfare-maximizing policy that aims to eliminate distortions associated with nominal rigidities can be approximated by a simple inflation targeting rule. Adding exchange rate into the feedback rule only marginally improves the stabilization properties of the policy rule. However, a rule reacting to wage inflation can be significantly welfare-improving. These results may suggest that in our medium-sized model the distortions associated with sticky wage setting have at least as important welfare implications as those related to the price stickiness in product markets.monetary policy, central banking, policy design

Numerical Validation of a Diurnal Streamflow-Pattern-Based Evapotranspiration Estimation Method

The evapotranspiration (ET) estimation method by Gr ibovszki et al. (2010b) has so far been validated only at one catchment because good q uality discharge time series with the required high enough temporal resolution can probably be fou nd at only a handful of watersheds worldwide. To fill in the gap of measured data, synthetic groundw ater discharge values were produced by a 2D finite element model representing a small catchment. Geome trical and soil physical parameters of the numerical model were changed systematically and it was checked how well the model reproduced the prescribed ET time series. The tests corroborated t hat the ET-estimation method is applicable for catchments underlain by a shallow aquifer. The slop e of the riparian zone has a strong impact on the accuracy of the ET results when the slope is steep, however, the method proved to be reliable for gentle or horizontal riparian zone surfaces, which are more typical in reality. Likewise, errors sligh tly increase with the decrease of riparian zone width, and unless this width is comparable to the width of the stream (the case of a narrow riparian zone), th e ET estimates stay fairly accurate. The steepness of the valley slope had no significant effect on the r esults but the increase of the stream width (over 4 m) strongly influences the ET estimation results, so t his method can only be used for small headwater catchments. Finally, even a magnitude change in the prescribed ET rates had only a small effect on the estimation accuracy. The soil physical parameters, however, strongly influence the accuracy of the method. The model-prescribed ET values are recovere d exactly only for the sandy-loam aquifer, because only in this case was the model groundwater flow system similar to the assumed, theoretical one. For a low hydraulic conductivity aquifer (e.g. clay, silt), root water uptake creates a considera bly depressed water table under the riparian zone, ther efore the method underestimates the ET. In a sandy, coarser aquifer the flow lines never become vertica l even bellow the root zone, so the method overestimates the ET rate, thus the estimated ET va lues need to be corrected. Luckily the prescribed and estimated ET rates express a very high linear c orrelation, so the correction can be obtained by th e application of a constant, the value of which solel y depends on soil type

Modern robotikai technológiai ismeretek oktatása „Teljes spektrumú” oktatási módszerrel : Application of “full-spectrum” teaching methods in the education of modern robotic technology

Napjainkban a feltörekvő technológiák és eszközök jelentős kihívást jelentenek az oktatási intézményeknek és oktatóknak egyaránt. Jelen cikk megkísérli a multidiszciplináris műszaki tudás átadását modern oktatási módszertan használatával egy változó tudáshátterű hallgatóságnak. A bemutatott módszertan alapképzésben indult bevezető robotikai kurzusban került felhasználásra. Jelen módszertan egyesíti a hagyományos pedagógiai módszereket a modernekkel, mint a projekt-alapú feladatok, önértékelés és projektbemutatók, hasonlóan egy miniszimpóziumhoz. A hallgatók visszajelzése alapján az új módszertan ígéretes, az eredmények egy része igazolja előzetes elvárásainkat, ugyanakkor felfedi a javítási lehetőségeket más tárgyak esetében is

State feedback design considering overexcitation

The state equation describing the relationship between the input signal u(t), the state variable x(t) and the output signal y(t) of a linear, time invariant nth order SISO process is:\textit dx/dt=Ax+Bu, y=Cx+Du. The transfer function between the output signal and the input signal of the process is: \textity(s)/u(s)=Wp(s) and the time constants characterizing the delays of signals due to energy storage elements result from the eigenvalues of the state matrix A. In the classical feedback control system, the controller computes the control signal according to the expression u(s)= Wc(s)[ua(s)-y(s)]. The reduction of signal delay in the process is implemented by the PID algorithm described by the transfer function Wc(s) that accelerates the feedback system by \textitoverexciting the control signal to a specified extent. The reduction of signal delay in the process can also be implemented by negative feedback of the state variables x. If the process is state controllable and the control signal is computed according to the algorithm u=kcua-Fx, the time constants of the feedback system can be freely specified by appropriate selection of F and kc. The design of the feedback gain F can be performed using the \textitAckermann formula; the system is accelerated by means of \textitoverexcitation of the control signal to an appropriate extent even in this case. The paper presents the fact that the gain can be chosen according to kc=[C(A-BF-1B]-1CA-1B, and the overexcitation ratio of the control signal can be calculated using the relationship u(0)/u(∞ )=[1+F(A-BF)-1B]-1. This overexcitation ratio is in connection with the rate of pole transfers that can be expressed analytically. It occurs frequently that the state variables x of the process cannot play any part in the computation of the control signal since the state variables cannot be measured. In such cases, the state feedback can be implemented from the state variables x*(t) of a state observer according to the expression u=kcuaFx*. The paper presents the fact that the state feedback implemented based on the state observer - as opposed to the common concept - can also be interpreted as a state feedback of the process model, with the task of computing the control signa l that fulfils the requirements of acceleration. This signal is applied at the input of both the process model and the real process

Evapotranspiration Calculation on the Basis of the Riparian Zone Water Balance

Riparian forests have a strong influence on groundwater levels and groundwater sustainedstream baseflow. An empirical and a hydraulic version of a new method were developed to calculateevapotranspiration values from riparian zone groundwater levels. The new technique was tested on thehydrometeorological data set of the Hidegvíz Valley (located in Sopron Hills at the eastern foothills ofthe Alps) experimental catchment. Evapotranspiration values of this new method were compared tothe Penman-Monteith evapotranspiration values on a half hourly scale and to the White methodevapotranspiration values on a daily scale. Sensitivity analysis showed that the more reliable hydraulicversion of our ET estimation technique is most sensitive (i.e., linearly) to the values of the saturatedhydraulic conductivity and specific yield taken from the riparian zone

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