Business Source Alumni Edition

Atsižvelgiant į darbo rinkos raidos netolygumus, siekiama įvertinti bendrųjų nedarbo rodiklių raidos tendencijas Lietuvoje. Esminis šiame darbe išskirtų gyventojų grupių situacijos darbo rinkoje diferenciacijos požymis – amžius. tačiau prioritetas čia teikiamas jaunimui. Kitas ryškus tyrimo prioritetas – nedarbas, nors plačiau analizuoti ir aktyvumo bei užimtumo rodikliai. Siekiant užtikrinti tyrime atliktos stebėsenos sistemiškumą, atlikta Valstybės duomenų agentūros (Lietuvos statistikos departamento) ir Užimtumo tarnybos nedarbo rodiklių lyginamoji analizė. Vertinant nedarbo (bedarbių skaičiaus) pokyčius, išskirtos paskiros jiems poveikį darančios veiksnių grupės. Vertinimo sistemiškumas užtikrinamas ir lyginant priešingas raidos kryptis išreiškiančių darbo rinkos rodiklių santykinius dydžius (užimtumo ir nedarbo), suteikiant jiems tiesioginę lyginamąją raišką. Maksimalus tyrime naudojamas laiko intervalas apima 1998–2021 m. laikotarpio statistinius ir administracinius duomenis. Kita vertus, siekiant ypač akcentuoti ankstesnės pandemijos poveikį, stebimų pasikeitimų tendencijų specifiką ir atsižvelgiant į duomenų disponavimo galimybes, straipsnyje išryškinami ir trumpalaikiai pokyčiai (iki 2022 m.), kurie apima 2–6 metų laikotarpį.

A simultaneous perturbation stochastic approximation (SPSA) method has been developed in this paper, using the operators of perturbation with the Lipschitz density function. This model enables us to use the approximation of the objective function by twice differentiable functions and to present their gradients by volume integrals. The calculus of the stochastic gradient by means of this presentation and likelihood ratios method is proposed, that can be applied to create SPSA algorithms for a wide class of perturbation densities. The convergence of the SPSA algorithms is proved for Lipschitz objective functions under quite general conditions. The rate of convergence [...] of the developed algorithms has been established for functions with a sharp minimum, as well as the dependence of the rate of convergence is explored theoretically as well as by computer simulation. The applicability of the presented algorithm is demonstrated by applying it to minimization of the mean absolute pricing error for the calibration of the Heston stochastic volatility model.

Business modelling is already a widespread term, however only some views of business have been investigated. Wide and comprehensive models of business are very informal and generic, and unambiguous and well-defined ones exist only for several narrow business areas. One of the essential parts of development of a high-level business concept including goals, strategy and the business plan, is choosing an approach to modelling and/or modelling notation. The latter challenges for OR applications and conceptual business modelling were the focus of the special IFORS Conference "Modelling and Simulation of Business Systems" (MOSIBUS), held on 13-14 May, 2003, Vilnius, Lithuania. Topics of the MOSIBUS covered but not only: • The formalization of business processes; • Methodology and tools of business system simulation; • Modeling of e-business and m-business systems; • Optimal decisions; • Knowledge-based management • Modelling and simulation of logistic systems; • Finance Modelling, etc. The MOSIBUS Conference was organised by the Lithuanian OR Society (LitORS, http:// www.mii.lt/LitORS) and the Baltic OR Society (BaltORS), and hosted by Kaunas University of Technology and Vilnius Gediminas Technical University in cooperation with other organizations. This Feature Issue is a visible result so far of the MOSIBUS as well as other events organised by LitORS and BaltORS consisting of 6 selected papers on the subject "Modelling and Simulation of Business Systems".