Oživotvorenje energetskih rješenja za očuvanje morskog okoliša od zakiseljavanja i zagrijavanja

Učinci onečišćenja i klimatskih promjena nadmašuju rezilijentnost mora i oceana, pa su europska mora ugrožena povećanjem temperature i zakiseljavanjem. Zakiseljavanje mora koje se ocjenjuje jednom od najtežih i najizravnijih planetarnih prijetnji je posljedica rastućih koncentracija ugljičnog dioksida. U poštivanju načela predostrožnosti, rješenje je u trenutnom smanjenju ispuštanja ugljičnog dioksida. Samo proizvodnja električne energije značajno utječe na globalne emisije ugljičnog dioksida jer se najviše oslanja na ugljen, ugljično najintenzivnije fosilno gorivo. Autorice u radu daju pregled relevantnih istraživanja o tranziciji na obnovljive izvore uz prijedlog rješenja prihvata energije iz potencijalno brojnih obnovljivih izvora u elektroenergetsku mrežu u Republici Hrvatskoj

Convergence Thresholds of Newton's Method for Monotone Polynomial Equations

Monotone systems of polynomial equations (MSPEs) are systems of fixed-point equations $X_1 = f_1(X_1, ..., X_n),$ $..., X_n = f_n(X_1, ..., X_n)$ where each $f_i$ is a polynomial with positive real coefficients. The question of computing the least non-negative solution of a given MSPE $\vec X = \vec f(\vec X)$ arises naturally in the analysis of stochastic models such as stochastic context-free grammars, probabilistic pushdown automata, and back-button processes. Etessami and Yannakakis have recently adapted Newton's iterative method to MSPEs. In a previous paper we have proved the existence of a threshold $k_{\vec f}$ for strongly connected MSPEs, such that after $k_{\vec f}$ iterations of Newton's method each new iteration computes at least 1 new bit of the solution. However, the proof was purely existential. In this paper we give an upper bound for $k_{\vec f}$ as a function of the minimal component of the least fixed-point $\mu\vec f$ of $\vec f(\vec X)$. Using this result we show that $k_{\vec f}$ is at most single exponential resp. linear for strongly connected MSPEs derived from probabilistic pushdown automata resp. from back-button processes. Further, we prove the existence of a threshold for arbitrary MSPEs after which each new iteration computes at least $1/w2^h$ new bits of the solution, where $w$ and $h$ are the width and height of the DAG of strongly connected components.Comment: version 2 deposited February 29, after the end of the STACS conference. Two minor mistakes correcte

Computing the Least Fixed Point of Positive Polynomial Systems

We consider equation systems of the form X_1 = f_1(X_1, ..., X_n), ..., X_n = f_n(X_1, ..., X_n) where f_1, ..., f_n are polynomials with positive real coefficients. In vector form we denote such an equation system by X = f(X) and call f a system of positive polynomials, short SPP. Equation systems of this kind appear naturally in the analysis of stochastic models like stochastic context-free grammars (with numerous applications to natural language processing and computational biology), probabilistic programs with procedures, web-surfing models with back buttons, and branching processes. The least nonnegative solution mu f of an SPP equation X = f(X) is of central interest for these models. Etessami and Yannakakis have suggested a particular version of Newton's method to approximate mu f. We extend a result of Etessami and Yannakakis and show that Newton's method starting at 0 always converges to mu f. We obtain lower bounds on the convergence speed of the method. For so-called strongly connected SPPs we prove the existence of a threshold k_f such that for every i >= 0 the (k_f+i)-th iteration of Newton's method has at least i valid bits of mu f. The proof yields an explicit bound for k_f depending only on syntactic parameters of f. We further show that for arbitrary SPP equations Newton's method still converges linearly: there are k_f>=0 and alpha_f>0 such that for every i>=0 the (k_f+alpha_f i)-th iteration of Newton's method has at least i valid bits of mu f. The proof yields an explicit bound for alpha_f; the bound is exponential in the number of equations, but we also show that it is essentially optimal. Constructing a bound for k_f is still an open problem. Finally, we also provide a geometric interpretation of Newton's method for SPPs.Comment: This is a technical report that goes along with an article to appear in SIAM Journal on Computing

The challenges for Croatian fisheries within current regulatory environment

Biodiversity as a planetary boundary and sustainability are strongly related to fish stocks and fisheries that are regulated by a number of sources of law with the aim of achieving their sustainability. The paper analyses current application, impact and effectiveness of the Common Fisheries Policy that sets the rules for fishing fleets management in the European Union and for fish stocks conservation as well as the 2020 Report on its implementation by the European Court of Auditors. It also examines the present and potential implementation and effects of Blue Growth, Marine Strategy Framework Directive, United Nations legal framework and Sustainable Development Goals on fisheries and aquaculture activities in the Adriatic Sea, a semi-enclosed and biodiversity rich sea. Improvements in implementing marine ecosystem approach and marine spatial planning are proposed in policy and regulatory framework, focusing on characteristics of the Adriatic Sea. Resilient solutions require placing more focus on characteristics of regional seas and applying site-specific tailor-made solutions and less complex but efficient governance for the seas which entail integrated approach to exploitation and preservation of the resources and their health

Evaluating Land Use Quality in Coastal Area Using Fuzzy Logic

The purpose of the paper is to propose a model for evaluating land use quality and its variations to be used for planning the use of the space, issuing the permits and producing the environmental impact studies. Elaborated is the case of Quarner bay situated in northern part of the Adriatic Sea. Input parameters considered are variation in size of impervious surfaces, transforming the coastal belt into industrial zone, pressures from maritime transport, road transport, utilities sector, power generation sources and technology and the quality of governance prevailing at national and local level. Fuzzy inference system is used to calculate the output land use quality parameter integrating health, environment, quality of living of the local community and of tourism. Selected input parameters should be further developed and constantly monitored