Reinforcement learning relocation assignment in the multiple-deep storage systemJakob Marolt
, Bojan Rosi
, Tone Lerher
, 2022, published scientific conference contribution
Abstract: The field of reinforcement learning shows promising results in recent publications for solving complex combinatorial problems. In this paper, an agent is trained to tackle the relocation problem that appears in various logistics systems. The relocation problem was formulated as an array that is accessible only from the top side. The agent has to relocate blocking SKUs and thus enable access to the SKU with the highest dispatch priority. We utilised the Deep Q-learning Network (DQN) to train the agent. Two case studies are presented – one with 1.2 ∙ 10 and another with 2 ∙ 10 possible states. The results display that the agents made a significantly better decision toward the learning process’s end than at the beginning
Keywords: relocation problem, reinforcement learning, DQN, multiple-deep, storage system
Published in DKUM: 14.03.2023; Views: 56; Downloads: 3
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5th International Conference EnRe - Energy & Responsibility : book of extended abstracts
Abstract: The tendency to improve energy devices, the impact of environmental factors and the development of new technologies for the exploitation of sustainable resources contribute to the fact that we have witnessed intensive energy development in the last decade. The two most important Slovenian energy pools, located in Velenje and Krško, are at the turning point of renovation, and are facing major challenges in the design and planning of modern energy devices. The current generation faces a great ethical responsibility to leave their descendants a world with as little human impact on the environment as possible. Therefore, communication between experts and researchers, discussion and exchange of different views for the future is of the utmost importance, which is exactly the purpose of the EnRe Conference.
Keywords: renewable energy and energy storage systems, classic energy systems, policies and strategies for RES, alternative energy systems, energy conversions, energy transfer, electrical machine, thermal machines, mathematical methods in energy engineering, environmental protection, micro and nano energetics, hydrogen technologies, low carbon technologies and strategies, nuclear energy, smart buildings, smart cities and smart grids
Published in DKUM: 09.06.2022; Views: 576; Downloads: 69
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Hollow-Fibre forward osmosis membrane module stress tests : diplomsko delo univerzitetnega študijskega programa I. stopnjeUrban Gselman
, 2020, undergraduate thesis
Abstract: Humanity has recently begun to realize that resources on Earth are not infinite and that, consequently, it is imperative for us to start to use them sustainably and renewably. Aligned with this mentality, forward osmosis has been rigorously studied in the past few decades with some commercially available products already on the market. This thesis used one of those products, namely, the Aquaporin HFFO 2 membrane module, and assessed its stability in sodium metabisulfite solution and high salinity without flowing solutions under long-term storage conditions. The sodium metabisulfite preservation part was devised to upgrade the existing guidelines for prolonged storage of fouled membranes and the osmotic drying project was looking at a scenario where the modules would be exposed to a salt solution on the draw side and no flowing wastewater on the feed side. The assessments were made on pristine HFFO 2 membrane modules and with RO water prepared on site. Their performance after exposure was measured with an internal quality control procedure, producing values for water flux, reverse salt flux, normalized reverse salt flux and temperature, which were later compared with the initial values. The findings show us that the sodium metabisulfite and increased salinity have a detrimental effect on the membrane inside of the module, but not enough to be considered damaged and would need to be discarded. More valuable results will be gained if the measurements are done on fouled membranes, as the biggest factor in increasing the lifetime of a module is preventing algal and bacterial growth
Keywords: forward osmosis, Aquaporin HFFO 2, sodium metabisulfite, osmotic drying, prolonged storage.
Published in DKUM: 24.09.2020; Views: 569; Downloads: 5
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ENERGY STORAGE BY MEANS OF SUPERCAPACITORSAlen Krunić
, 2020, master's thesis
Abstract: Nowadays, traditional sources are mostly used for energy production, such as fossil and nuclear fuels. Such energy sources have a negative impact on the environment. As a result, trends in energy production are increasingly focused on renewable energy sources. These energy sources are available everywhere and their environmental impact is minimal. Nonetheless, these energy sources cannot be exploited with the same efficiency during the day (the Sun is not present the whole day, in winter, the sunlight days are shorter, the wind is not constant, etc.) or during different periods of the year. The variable amount of energy, produced from these sources and the integration with energy distribution systems, must not be overlooked. This is especially important in power plants, where it is necessary to ensure high energy reserves at excess load, which can be achieved by incorporating an improved energy storage system and higher efficiency of produced electricity. This process contributes to a significant reduction in costs. Direct energy storage systems, described in this master's thesis, are used in applications that require many fast charging and discharging cycles instead of a long-term energy storage in cars, buses, trains and lifts, where they are used for regenerative braking, short-term energy storage or as a primary source of electricity. Supercapacitors are electrochemical double-layer capacitors with low energy density and high power density. They have low series resistance, so they have the ability to emit high current, allowing them to charge quickly and a long lifespan. The goal of the thesis is to determine experimental parameters of supercapacitors and to compare them with theoretical parameters and batteries. With the simulation method of charge and discharge we have proven, that differences in results exists.
Keywords: storage, supercapacitor, application, modelling
Published in DKUM: 02.03.2020; Views: 1658; Downloads: 224
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Analysis of concentration and sedimentation of suspended load in the reservoirsHelena Vrecl-Kojc
, Bojana Dolinar
, Roman Klasinc
, Ludvik Trauner
, 2008, original scientific article
Abstract: This paper deals with the sedimentation of suspended load in the reservoirs. As an example the reservoir of the hydroelectric power plant Boštanj on the Sava River is shown. The objective of the described studies was to determine the quantity and type of deposited material in the reservoir during the selected time period. For this purpose, the mineral and chemical composition, and the concentration and the particle size of the suspended load at the intake of the water into the reservoir and at its outflow were examined. In order to determine the concentration of the suspended load, 24 water samples from the area of the intake and outflow from the reservoir were taken. At the same time the discharge of the Sava River was measured. Solid particles were removed from the water with the help of sedimentation and in the final stage of water evaporation. The results of the studies showed that the concentration of the suspended material was changing in relation to the location and the flow rate of the water. This ratio can be described with an exponential function.
In suspended load composition carbonates, muscovite/illite and quartz dominate; however, chlorite was also found, as well as small quantities of plagioclase and organic detritus. With regard to the size of the particles the examined samples are classified as silt.
It was determined that the concentration of the suspended load, at the same flow rate of water, at the intake into the reservoir is larger than at the outflow. The difference is represented by the material that was sedimented in the reservoir due to the decreased speed of the water as a result of the river's impoundment. A comparison of the composition of the samples from both collection sites showed that at the outflow site of the water from the reservoir there is a somewhat smaller share of carbonate grains and heavy minerals than at the intake site, and a higher content of organic detritus and clay particles can also be observed. Considering the actual discharge of water in the period between July 2006 and July 2007 and the examined ratio between the flow rate of the water and the quantity of suspended and deposited material, the total quantity of sedimented material in this period was estimated.
Keywords: suspended load, sedimentation, sediment transport, water storage reservoir
Published in DKUM: 05.06.2018; Views: 1619; Downloads: 65
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Method for evaluating the throughput performance of shuttle based storage and retrieval systemsTone Lerher
, Banu Ekren
, Zaki Sari
, Bojan Rosi
, 2016, original scientific article
Abstract: In this paper a method for throughput performance calculation of shuttle based storage and retrieval systems (SBS/RS) is presented. SBS/RS represent a new technology in automated storage and retrieval systems. Since it is important to design SBS/RS right the first time due to the relative inflexibility of the physical layout, we provide a proposed method for the throughput performance calculation of these systems. The performance of the system is considered as a throughput capacity of the SBS/RS as a whole.
Keywords: automated warehouses, performance analysis, shuttle based systems, storage, logistics
Published in DKUM: 12.07.2017; Views: 1119; Downloads: 424
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Vpeljava storitve "upravljanje diskovnih polj"Uroš Pernuš
, 2016, bachelor thesis/paper
Abstract: Diplomska naloga obravnava vpeljavo storitve, ki omogoča upravljanje diskovnih polj. Predstavljena je definicija pojmov, kot so diskovno polje, funkcije diskovnih polj, programsko definirani podatkovni center, programsko definirani pomnilnik. Opisane so glavne značilnosti rešitve IBM Tivoli Storage Productivity Center (TSPC), ki omogoča upravljanje heterogenih virov podatkov. Za konkretnega naročnika je bila opravljena analiza stanja, ki je pokazala, da je upravljanje več kot dvesto terabajtov podatkov nepregledno, reševanje težav zaradi razdrobljenosti upravljanja prepočasno in da obstaja visoko tveganje za izpad storitve. Definirana je bila storitev Upravljanje diskovnih polj. V nalogi so prikazane komponente prototipne rešitve in primeri poročil o obremenitvi tako stikal za diskovna polja kot tudi samih diskovnih polj. Storitev je vpeljana v uporabo in omogoča pravočasno zaznavo težav, alarmiranje v primeru neželenih dogodkov ter bistveno zmanjša napor izvajalcev storitve.
Keywords: upravljanje diskovnih polj, programsko definirano diskovno polje, IBM Tivoli Storage Productivity Center, sporazum o ravni storitve
Published in DKUM: 07.10.2016; Views: 1159; Downloads: 88
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UPRAVLJANJE VARNOSTNIH KOPIJ V MALEM PODJETJUSimon Hribar
, 2016, bachelor thesis/paper
Abstract: Diplomsko delo prikazuje postopek prenove in uvedbe celovite rešitve varnostnega kopiranja podatkov v podjetju, ki je iz mikro podjetja zraslo v malo podjetje, tehnologija izdelave varnostnih kopij pa rasti ni sledila. To je privedlo do težav pri izdelavi ustreznih varnostnih kopij. Zaradi neustrezne rešitve izdelave varnostnih kopij se je pojavila resna grožnja za podatke, ki so neprecenljivi za delovanje in obstoj podjetja.
V diplomskem delu proučujemo vse korake od predpriprave do uvedbe rešitve, ki so bili potrebni za izdelavo arhitekture rešitve in izbiro strojne opreme, s katero smo rešitev podprli. Za programsko opremo za varnostno kopiranje podatkov smo izbrali IBM Tivoli Storage Manager (TSM), s katero smo pokazali postopke od priprave strežnika TSM kot glavne komponente rešitve do konfiguracije, potrebne za delovanje TSM-jevih klientov, ki izvajajo operacije varnostnega kopiranja na sistemih.
Prikazujemo pravila za pripravo politik varovanja podatkov na strežniku TSM, z razlago dejansko uporabljenih nastavitev v naši rešitvi za varnostno kopiranje vseh poglavitnih sistemov v podjetju. Z oddajo upravljanja rešitve zunanjemu izvajalcu je podjetju uspelo rešiti vse probleme z varnostnim kopiranjem brez dodatnih investicij v izobraževanje zaposlenih za upravljanje rešitve.
Keywords: Malo podjetje, IBM Tivoli Storage Manager, varnostne kopije podatkov.
Published in DKUM: 01.07.2016; Views: 994; Downloads: 100
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Načrtovanje avtomatiziranih regalnih skladiščnih sistemov z uporabo simulacijskega postopkaIztok Potrč
, Tone Lerher
, Janez Kramberger
, Matjaž Šraml
, 2004, original scientific article
Abstract: V prispevku je predstavljen simulacijski model avtomatiziranega regalnega skladiščnega sistema z enojno pomično in večpomičnimi mizami. Glavni namen predstavljene raziskave je določitev zmogljivosti sistema z večpomičnimi mizami, glede na sistem z enojno pomično mizo. Slednje pomeni glavni delež in pomoč pri postopku načrtovanja avtomatiziranega regalnega skladiščnega sistema. Povečanje pretočne zmogljivosti transportno-skladiščnih enot je mogoče z uporabo sistema z večpomičnimi mizami, glede na sistem z enojno-pomično mizo. V inženirski praksi se največkrat uporablja sistem z enojno pomično mizo, ki temelji na dvojnem delovnem krogu, medtem ko sistem z večpomičnimi mizami temelji na štirikratnem in šestkratnem delovnem krogu. Problem se pojavi pri uporabi ustrezne upravljalne strategije, za zagotovitev pogoja o najmanjših vožnjah regalnega dvigala. V ta namen smo uporabili posebno domiselno metodo, poimenovano "Strategija x", ki razvrsča zaporedje skladiščnih in odpremnih zahtev, z namenom po minimizaciji povprečnega časa vožnje regalnega dvigala. Za ovrednotenje domiselne metode s sistemom večpomičnih miz smo uporabili tehniko diskretnih numeričnih simulacij. Rezultati simulacijske analize so pokazali očitno povečanje pretočnih zmogljivosti sistema z večpomičnimi mizami v primerjavi s sistemom enojne pomične mize.
Keywords: transport systems, high storage racks, automated warehousing, discrete event simulation, storage operation, performance analysis
Published in DKUM: 10.07.2015; Views: 1326; Downloads: 41
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Preliminary estimation of bryophyte biomass and carbon pool from three contrasting different vegetation typesMahesh Kumar Singh
, Anita Juhász
, Zsolt Csintalan
, Mitja Kaligarič
, Michal V. Marek
, Otmar Urban
, Zoltán Tuba
, 2005, published scientific conference contribution
Abstract: Bryophytes are the primary form of carbon storage in many ecosystems. There is growing consensus within the scientific community that increases in atmospheric carbon dioxide (CO2) enhancing the earth's natural greenhouse effect. Because of the potential effects of these gases on the global enery budget and future elimate, there is an urgent need to quantify terrestrial sources and sinks of carbon. There is more carbon stored in some bryophytes than in any other genus of vascular or non-vascular plants (Clymo & Hayward, 1982). Predicting how the vast stores of carbon in moss-dominated ecosystems will be affected by anthropogenic disturbance is critical for models of global climate change (Post et al., 1982). Bryophytes are a prominent feature of many forest and grassland types, where they can make an important contribution to carbon balance (Delucia, et al., 2003). Tropical montane rain forest, because of their complexity and variety of microhabitats, usually harbors a rich diversity of bryophytes. Even though they are often small and inconspicuous, especially in the lowland forest, they may play a significant role in the forest ecosystem (Frahm, 1994). Similarly, bryophytes in the temperate forest and grasslands are thought to be an important carbon sink (O'Neill, 2000). The objective of this research was to estimate components of the bryophyte biomass and approximate amount of carbon stored in it.
Keywords: vegetation, habitats, geoelements, carbon, carbon storage, bryophyte, bryophyte biomass
Published in DKUM: 07.06.2012; Views: 1633; Downloads: 130
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