Solving the k-center Problem Efficiently with a Dominating Set Algorithm

We present a polynomial time heuristic algorithm for the minimum dominating set problem. The algorithm can readily be used for solving the minimum alpha-all-neighbor dominating set problem and the minimum set cover problem. We apply the algorithm in heuristic solving the minimum k-center problem in polynomial time. Using a standard set of 40 test problems we experimentally show that our k-center algorithm performs much better than other well-known heuristics and is competitive with the best known (non-polynomial time) algorithms for solving the k-center problem in terms of average quality and deviation of the results as well as execution time

Analiza vpliva parkljaste divjadi na pomlajevanje dinarskega jelovo-bukovega gozda na raziskovalni ploskvi Trnovec v Kočevskem gozdnogospodarskem območju

In the period 1970-2000, 152 fenced-in areas were built in the Kočevje Forest Management Region with an aim to protect tree seedlings and saplings from ungulatesć activity and to monitor the influence of roe and red deer on natural regeneration. The average surface area of fenced areas is 0.71 ha. Using the pair comparison technique (fenced vs. unfenced areas), the structureand the composition of the natural regeneration of tree species as well as complete shrub and herb vegetation were analysed in the research site Trnovec. Furthermore, the vegetation was investigated using the Braun-Blanquetmethod. The research results show significant differences between fenced and unfenced areas, both in tree species composition and in theheight structure of the sapling community. In fenced areas the total numberof saplings taller than 50 cm is higher and an increase is also evident in the number of saplings of silver fir Abies alba, sycamore Acer pseudoplatanus, elm Ulmus glabra and other minor tree species. There are also significant differences in species composition and in the abundance of plant species in the herb layer. The results show that natural regeneration of Dinaric fir-beech forests is successful, provided the influence of ungulates is excluded.V gozdnogospodarskem območju Kočevje so v obdobju 1970-2000 zgradili 152 gozdnih ograj, ki so namenjene zaščiti pomladka in mladovja pred velikimi rastlinojedi in preučevanju vpliva populacij jelenjadi in srnjadi na razvoj rastlinja. Poprečna velikost ograjene površine je 0,71 ha. Z vzorčenjem na transektu (N=42 ploskev, 4x4 m) v raziskovalnem objektu Trnovec smo podrobno raziskali sestavo in strukturo pomladka in drugega rastlinja v zeliščni in grmovni plasti na ograjeni in neograjeni površini. Analizo rastlinja smo dopolnili s tremi fitocenološkimi popisi. Pri parni primerjavi smo ugotovili značilne razlike v višinski strukturi in sestavi pomladka. Na ograjeni površini smo evidentirali več mladic, ki so višje od 50 cm, in znatno večje število mladic jelke (Abies alba), javorja (Acer pseudoplatanus), bresta (Ulmus glabra) in drugih minoritetnih drevesih vrst. Značilne so tudi razlike v sestavi in obilju zelnatih rastlin. Ob izključitvi vpliva jelenjadi in srnjadi poteka naravna obnova povsem nemoteno

Physics Learning in Primary and Secondary Schools with Computer Games—An Example — Angry Birds

In this paper, we discuss how we can make physics lessons more interesting with the use of information and communications technology (ICT). We explain why physics teachers need to be ICT competent and which ICT tools teachers can use to improve their lessons. Nowadays, many learners spend their free time playing computer games that use basic physics laws for game mechanics. One of our goals was to find out which computer games would be appropriate for learning physics and how to include those games in the learning process. We also show an example how to teach physics using the computer game Angry Birds, where we take into account primary and secondary school curriculum. Finally, we analyze how teaching physics with computer games affect students and what are the benefits and weaknesses using this method. In addition, we conduct a survey to gain insight on the opinion of physics teachers about the appropriateness of the computer game Angry Birds for teaching physics in elementary and high school. Surprisingly, the teachers find the game more appropriate for the teaching of physics in elementary school, despite of the fact that there are physics themes mostly from high school physics included in the game

Beyond Dataflow

This paper presents some recent advanced dataflow architectures. While the dataflow concept offers the potential of high performance, the performance of an actual dataflow implementation can be restricted by a limited number of functional units, limited memory bandwidth, and the need to associatively match pending operations with available functional units. Since the early 1970s, there have been significant developments in both fundamental research and practical realizations of dataflow models of computation. In particular, there has been active research and development in multithreaded architectures that evolved from the dataflow model. Also some other techniques for combining control-flow and dataflow emerged, such as coarse-grain dataflow, dataflow with complex machine operations, RISC dataflow, and micro dataflow. These developments have also had certain impact on the conception of highperformance superscalar processors in the “post-RISC” era

A Feature-Based Comparison of Evolutionary Computing Techniques for Constrained Continuous Optimisation

Evolutionary algorithms have been frequently applied to constrained continuous optimisation problems. We carry out feature based comparisons of different types of evolutionary algorithms such as evolution strategies, differential evolution and particle swarm optimisation for constrained continuous optimisation. In our study, we examine how sets of constraints influence the difficulty of obtaining close to optimal solutions. Using a multi-objective approach, we evolve constrained continuous problems having a set of linear and/or quadratic constraints where the different evolutionary approaches show a significant difference in performance. Afterwards, we discuss the features of the constraints that exhibit a difference in performance of the different evolutionary approaches under consideration.Comment: 16 Pagesm 2 Figure

Building Information Modeling with DDS-CAD program

V diplomski nalogi obravnavamo koncept načrtovanja objektov, znanega kot informacijsko modeliranje stavb. V tujini je ta koncept načrtovanja v projektantskih birojih že dobro uveljavljen, medtem ko je v Sloveniji še v povojih. Ker imajo v gradbeni industriji pomembno vlogo tudi inženirji strojništva, so na trgu posebni modelirni programi za načrtovanje strojnih sistemov. Sem spada tudi program DDS-CAD, ki smo ga na izbranem objektu uporabili za načrtovanje sistemov prezračevanja. Za primer smo izbrali stavbo Gimnazija Vič ter njen prizidek telovadnice, knjižnice in večnamenskih prostorov. Glede na dvodimenzionalne načrte objekta smo izdelali model in sisteme prezračevanja v treh dimenzijah. Iz programa smo pridobili podatke sistemov prezračevanja, kot so uporabljeni elementi, izračun pretoka zraka in padcev tlaka. Definirali smo sestavo ovoja ter pridobili podatke o toplotnih izgubah objekta.The thesis deals with the concept of building design known as Building Information Modeling (BIM). Abroad, this concept of modeling has already been well established in design bureaus, but it is still in its infancy in Slovenia. Since mechanical engineers also play an important role in the construction industry, there are special modeling programs for the design of building systems. This includes the DDS-CAD program, which we used on the selected building for the design of ventilation systems. For example we chose the building Gimnazija Vič, and its annex of the gym, library and multipurpose rooms. Depending on the two-dimensional building plans, we developed a model and ventilation systems in three dimensions. From the program we obtained data from ventilation systems, such as used elements, the calculation of air flow and pressure drops. We defined the structure of the walls, and obtained data for heat losses of the building

Hydraulic modeline of pump systems in water distribution networks

Water distribution networks provide water supply to consumers. Pumping system adds mechanical work, thus providing sufficient amount of energy for water distribution throughout network. Pump's mechanical work is made by consuming electrical power. Because consumption of electricity and costs of consumed energy are high improvements made on operation of pumping system can lead to non negligible savings. When optimising pump system's operation different factors have to be taken into account (hydraulic laws, consumption pattern, changes of tariff of electricity) while trade off between energy consumtion costs at one hand and number of pump switches (and thus related pump maintenance costs) at the other hand is always present. Following this criteria several solutions exist which create solution space. According to these and other requirements, specific to a problem, one of possible solutions is chosen

Hydrological analysis of floods for the Ljubljanica river basin

Ljubljansko barje is the largest floodplain in Slovenia. Heavy rainfall in predominantly karst\ud catchment area of Ljubljanica river instigate flooding of Ljubljansko barje, caused by river\ud Ljubljanica and its torrential tributaries such as Iška at the south side and Gradaščica at the\ud north side of Ljubljansko barje. On the one hand, flooding of Ljubljansko barje is beneficial to\ud the city of Ljubljana as it lowers the risk of flooding in the city, while on the other hand, it\ud poses danger to the inhabitants of settlements of Ljubljansko barje. This thesis analyses\ud hydrology of the largest floods of Ljubljansko barje since the beginning of the 20th century,\ud such as floods in 1926, 1933 and 2010.\ud Analysis results indicate that flooding of Ljubljansko barje occurs in combination with highintensity\ud precipitation that lasts for couple of days. Flooding of this area can also occur after\ud longer periods of lower-intensity precipitation followed by precipitation of higher intensity due\ud to lower water retention capability of catchment area of Ljubljanica. Flooding of river\ud Ljubljanica on Ljubljansko barje initiate gradually and last for several days or even few\ud weeks. On the contrary, flash floods are characteristic of torrential tributaries Gradaščica and\ud Iška. Main causes of flooding of Ljubljansko barje are quantity and duration of precipitation\ud and high antecedent precipitation index. Results show that floodings of Ljubljansko barje\ud usually occur in autumn. Trends in seasonal precipitation and continuous settlement of the\ud ground of Ljubljansko barje indicate severer effects of flooding in this area in the future