Denna rapport utreder möjligheterna till att reducera ledtiden, med en uppskattning av minst 10%, för plockprocessen på den utlevererande avdelningen som kallas den ”avgående avdelningen” hos EJOT Sverige AB i Örebro. Företaget vill i dagsläget skapa sig en tydlig helhetsbild av processen samt få underlag, för eventuell framtida implementering, i form av förbättringsförslag för en ledtidsreducering. Under arbetets gång beskrivs nuläget utifrån datainsamling, intervjuer och observationer, i kombination med ett spagettidiagram som presenteras. De möjliga rotorsakerna till problemen kartläggs genom att skapa ett fiskbensdiagram som sedan analyseras. Analyserna visar på att processen är komplex och därmed även problemen. Orsaker som valts för vidare analys är: layout, körslinga och placering av låga gods.  Tre förbättringsförslag har tagits fram utifrån analyserna och dessa handlar om att skapa en ny optimerad layout, en ny optimerad körslinga samt att eliminera placeringen av låga gods.  Det fortsatta arbetet bör vara att optimera en ny lagerlayout samt se över och standardisera en ny körslinga. Företaget bör också se över möjligheterna att eliminera placeringen av gods på markplan. / This report investigates the possibilities of reducing the lead time, with an estimate of at least 10%, for the picking process at the delivery unit called the “outgoing department” at EJOT Sverige AB in Örebro. The company currently wants to create an overall picture of the process and get a basis, for possible future implementation, in the form of improvement proposals for a lead time reduction. During the work, the current situation is described based on data collection, interviews and observations, in combination with a spaghetti diagram that is presented. The possible root causes of the problems are mapped by creating an Ishikawa diagram which is then analyzed. The analyses show that the process is complex and thus also the problems. Reasons chosen for further analysis are: layout, driving loop and placement of low goods. Three improvement proposals have been developed based on the analyses and these are about creating a new optimized layout, a new optimized driving loop and eliminating the placement of low goods. The continued work should be to optimize a new warehouse layout and review and standardize a new driving loop. The company should also review the possibilities of eliminating the placement of goods on the ground floor.

Topological materials have discovered ultrahigh magnetoresistance, chiral anomalies, the inherent anomalous Hall effect, and unique Fermi arc surface states. Topological materials now include insulators, metals, and semimetals. Weyl semimetals (WSM) are topological materials that show linear dispersion with crossings in their band structure which creates the pair of Weyl nodes of opposite chirality. WSMs have topological Fermi arc surface states connecting opposing chirality Weyl nodes. Spin-orbit coupling can result in the band opening in Dirac nodal rings, and creating the pair of Weyl nodes either by breaking the time-reversal or spatial inversion symmetry (but not both) 1-3. The chirality of a Weyl node is set by the Berry flux through a closed surface in reciprocal space around it. The purpose of this thesis was to characterize and investigate the thermodynamic stability of WSM. To accomplish these goals, quantum mechanical modeling at the level of density functional theory (DFT) was used. WloopPHI, a Python module, integrates the characterization of WSMs into WIEN2k, a full-potential all-electron density functional theory package. It calculates the chirality of the Weyl node (monopole charge) with an enhanced Wilson loop method and Berry phase approach. First, TaAs, a well-characterized Weyl semimetal, validates the code theoretically. We then used the approach to characterize the newly discovered WSM YRh6Ge4, and we found a set of Weyl points into it. Further, we study the stability of the kagome-based materials A3Sn2S2, where A is Co, Rh, or Ru, in the context of the ternary phase diagrams and competing binary compounds using DFT. We demonstrated that Co3Sn2S2 and Rh3Sn2S2 are stable compounds by examining the convex hull and ternary phase diagrams. It is feasible to synthesize Co3Sn2S2 by a chemical reaction between SnS, CoSn and Co9S8. Moreover, Rh3Sn2S2 can be produced by SnS, RhSn and Rh3S4. On the other hand, we found that Ru3Sn2S2 is a thermodynamically unstable material with respect to RuS2, Ru3S7 and Ru. Our work provides some insights for confirming materials using the DFT approach. 1. S. M. Young et al. Dirac Semimetal in Three Dimensions. Physical Review Letters108(14) (2012), 140405. 2. J. Liu and D. Vanderbilt. Weyl semimetals from noncentrosymmetric topological insulators. Physical Review B 90(15) (2014), 155316. 3. H. Weng et al. Weyl Semimetal Phase in Noncentrosymmetric Transition-Metal Monophosphides. Physical Review X 5(1) (2015), 011029. / Thesis / Master of Applied Science (MASc)

This thesis has analyzed the design process within the Lean Manufacturing Equipment (LME) department of Virtual Manufacturing AB. This department offers customized solutions to improve the flow, processes, and ergonomics in internal logistics and material handling. The work incorporates scientific theories within Lean, such as Just-in-Time, Kaizen, and Jidoka. Additionally, theories on lean waste were also utilized.By examining an LME-project conducted in the summer of 2023, where several problems arose, a root cause analysis was performed. This was done by first identifying the responsibilities of the designers in the LME-process. Subsequently, an Ishikawa-diagram was created, focusing on the involvement of the designers. Finally, three areas of causation were selected and analyzed more thoroughly using the "5 Whys?" Method.The result of this method provided solutions in the form of three improvement suggestions, which are: • Automated tool for wheel selection.• Standardization of categorization of Karakuri products.• Improvement of documentation for revisions.These improvement suggestions were analyzed from a Lean perspective as well as their social, economic, and environmental sustainability. / Detta examensarbete har analyserat konstruktionsprocessen inom Virtual Manufacturing AB:savdelning Lean Manufacturing Equipment (LME). Denna avdelning erbjuder kundanpassade lösningar för att förbättra flödet, processer och ergonomin inom internlogistik och materialhantering. Detta arbete omfamnar vetenskaplig teori inom Lean så som Just-in-Time, Kaizen och Jidoka. Utöver detta nyttjades även teori om lean-slöserier.Genom att undersöka ett LME-projekt som genomfördes sommaren 2023 där flertalet problem uppstod gjordes en rotorsaksanalys. Detta gjordes genom att först konstatera konstruktörernas ansvar i LME-processen. Vidare skapades ett Ishikawa-diagram som sedan avgränsades till konstruktörernas involvering. Slutligen valdes tre orsaksområden som analyserades mer noggrant med hjälp av metoden “5 Varför?”.Resultatet av denna metod gav lösningar i form av tre förbättringsförslag, vilka är:• Automatiserat hjälpmedel för val av hjul.• Standardisering av kategorisering av Karakuri-produkter.• Förbättring av dokumenteringen av revisioner.Dessa förbättringsförslag analyserades från ett lean-perspektiv samt deras sociala, ekonomiska och miljömässiga hållbarhet.

Traffic growth and limited roadway capacity decrease traveler mobility and increase traffic congestion and fuel consumption. Traffic managers employ various control techniques to mitigate the aforementioned problems. One well-known network-wide control strategy is perimeter control (or gating). Perimeter control is based on the Network Fundamental Diagram (NFD). NFD-based perimeter control techniques are used to solve congestion problems in transportation networks. One well-known method used in the literature is Proportional Integral Control (PIC). PIC solves the congestion problem, but suffers from sensitivity to parameter tuning and the need for model linearization. A weather-tuned perimeter control (WTPC) and a jam density-tuned perimeter controller (JTPC) were developed to cope with parameter sensitivity for different weather conditions and jam densities, respectively. In an attempt to overcome PIC problems, a sliding mode controller (SMC) was developed. SMC does not require model linearization and parameter tuning. It is also robust to varying demand patterns. SMC computes the flow that needs to enter a protected network and converts it to corresponding traffic signal timings to achieve the desired control strategies. Another approach to implementing the sliding mode controller is to control vehicle speeds on the links entering the protected network. Coupling speed harmonization (SH) with sliding mode control (SMC), an SMC-SH was developed and implemented in the INTEGRATION microscopic traffic simulator. The mentioned controllers are all tested on a mid-size grid network replicating downtown Washington DC. SMC-SH improved different performance metrics on the whole grid network compared to the no control case. Specifically, it improved average travel time, total delay, stopped delay, fuel consumption, CO2 emissions by 17.27%, 18.18%, 12.76%, 5.91%, and 7.04%, respectively. In order to test the SMC-SH on a real large-scale network, the downtown Los Angeles (LA) network is used. The LA network is known for its congested freeways, so a development of a Freeway-SMC-SH controller is performed and tested. It shows good results in improving the performance not only of freeways, but also the overall LA network performance. Particularly, the network-wide average travel time, total delay, stopped delay, fuel consumption and CO2 emissions improved with respect to the no control case by 12.17%, 20.67%, 39.58%, 2.6%, and 3.3%, respectively. An identification of a homogeneously congested area is needed to apply SMC-SH on LA roads (not freeways). The geographical self organizing maps (GeoSOM) clustering algorithm is applied and tested on the LA network. The clustering goal is to identify a geographically connected region with small density variance. GeoSOM is able to achieve that objective with better performance than the state-of-the-art Kmeans and DBSCAN clustering algorithms. The enhancements reached up to 15.15% for quantization error, 61.05% for spacial quantization error, and 43.96% for variance. Finally, the SMC-SH is tested on the protected region of the LA network identified by the GeoSOM algorithm. SMC-SH succeeds in improving network-wide vehicle travel time, total delay, stopped delay, fuel consumption and CO2 emissions by 6.25%, 9.4%, 16.47%, 1.7%, and 2.19%, respectively. / Doctor of Philosophy / Road congestion causes vehicular delays and increases travel time and fuel consumption. The goal of the research is to prevent or relieve traffic congestion in a network. That region that we attempt to address is termed the congested network or the protected network (PN). One way to solve the traffic jam problem is to set up gates on the PN borders so that the number of vehicles that enter the network is limited, and consequently traffic jams do not occur. However, the number of vehicles should not be limited too much to avoid overcrowding outside the PN. The developed controller calculates the right number of cars that should enter the network in order to improve the performance inside and outside the PN. The first way to apply the controller commands is to adjust traffic signal timings at the traffic signals located along the PN border. The second way (called SMC-SH) is to adjust the speed of the vehicles entering the network through these gates. In the first part of the work, all the controllers are implemented and tested in a mid-size grid network. In the second part of the work, the goal is to implement the controller on the real large-scale Los Angeles (LA) network. Since the LA network suffers from congestion on freeways, a freeway controller is developed and tested. It does not only succeed in reducing traffic jams on freeways, but also enhances the overall LA network traffic performance. In order to apply the SMC-SH controller on the LA network, we identify homogeneously congested regions. GeoSOM clustering is implemented to achieve this goal and compared to other clustering methods, and is shown to outperform them. Finally, the SMC-SH controller is tested on the congested region of LA, and succeeds in reducing travel time, total delay, and fuel consumption for the LA network.

Modern database systems use a query optimizer to identify the most efficient strategy, called “query execution plan”, to execute declarative SQL queries. The role of the query optimizer is especially critical for the complex decision-support queries featured in current data warehousing and data mining applications. Given an SQL query template that is parametrized on the selectivities of the participating base relations and a choice of query optimizer, a plan diagram is a color-coded pictorial enumeration of the execution plan choices of the optimizer over the query parameter space. Complementary to the plan-diagrams are cost and cardinality diagrams which graphically plot the estimated execution costs and cardinalities respectively, over the query parameter space. These diagrams are collectively known as optimizer diagrams. Optimizer diagrams have proved to be a powerful tool for the analysis and redesign of modern optimizers, and are gaining interest in diverse industrial and academic institutions. However, their utility is adversely impacted by the impractically large computational overheads incurred when standard brute-force approaches are used for producing fine-grained diagrams on high-dimensional query templates. In this thesis, we investigate strategies for efficiently producing close approximations to complex optimizer diagrams. Our techniques are customized for different classes of optimizers, ranging from the generic Class I optimizers that provide only the optimal plan for a query, to Class II optimizers that also support costing of sub-optimal plans and Class III optimizers which offer enumerated rank-ordered lists of plans in addition to both the former features. For approximating plan diagrams for Class I optimizers, we first present database oblivious techniques based on classical random sampling in conjunction with nearest neighbor (NN) inference scheme. Next we propose grid sampling algorithms which consider database specific knowledge such as(a) the structural differences between the operator trees of plans on the grid locations and (b) parametric query optimization principle. These algorithms become more efficient when modified to exploit the sub-optimal plan costing feature available with Class II optimizers. The final algorithm developed for Class III optimizers assume plan cost monotonicity and utilize the rank-ordered lists of plans to efficiently generate completely accurate optimizer diagrams. Subsequently, we provide a relaxed variant, which trades quality of approximation, for reduction in diagram generation overhead. Our proposed algorithms are capable of terminating according to user given error bound for plan diagram approximation. For approximating cost diagrams, our strategy is based on linear least square regression performed on a mathematical model of plan cost behavior over the parameter space, in conjunction with interpolation techniques. Game theoretic and linear programming approaches have been employed to further reduce the error in cost approximation. For approximating cardinality diagrams, we propose a novel parametrized mathematical model as a function of selectivities for characterizing query cardinality behavior. The complete cardinality model is constructed by clustering the data points according to their cardinality values and subsequently fitting the model through linear least square regression technique separately for each cluster. For non-sampled data points the cardinality values are estimated by first determining the cluster they belong to and then interpolating the cardinality value according to the suitable model. Extensive experimentation with a representative set of TPC-H and TPC-DS-based query templates on industrial-strength optimizers indicates that our techniques are capable of delivering 90% accurate optimizer diagrams while incurring no more than 20% of the computational overheads of the exhaustive approach. Infact, for full-featured optimizers, we can guarantee zero error optimizer diagrams which usually require less than 10% overheads. Our results exhibit that (a) the approximation is materially faithful to the features of the exact optimizer diagram, with the errors thinly spread across the picture and Largely confined to the plan transition boundaries and (b) the cost increase at the non-sampled point due to assignment of sub-optimal plan is also limited. These approximation techniques have been implemented in the publicly available Picasso optimizer visualizer tool. We have also modified PostgreSQL’s optimizer to incorporate costing of sub-optimal plans and enumerating rank-ordered lists of plans. In addition to these, we have designed estimators for predicting the time overhead involved in approximating optimizer diagrams with regard to user given error bounds. In summary, this thesis demonstrates that accurate approximations to exact optimizer diagrams can indeed be obtained cheaply and consistently, with typical overheads being an order of magnitude lower than the brute-force approach. We hope that our results will encourage database vendors to incorporate the foreign-plan-costing and plan-rank-list features in their optimizer APIs.

Part I: The present work is to calculate dimensionless three-dimensional universal phase and lift force diagrams for a microbubble or pendant drop in a static liquid on a solid surface or orifice. Studying microbubble dynamics is important due to its controlling mass, momentum, energy and concentration transfer rates encountered in micro- and nano-sciences and technologies. In this work, dimensionless phase and force diagrams are presented by applying an equation for microbubble shape to accuracy of the second order of small Bond number provided by O¡¦Brien (1991). Two dimensionless independent parameters, Bond number and contact angle (or base radius), are required to determine dimensionless phase and force diagrams governing static and dynamic states of a microbubble. The phase diagram divides the microbubble surface into three regions, the apex to inflection, inflection to neck, and neck to the edge of microbubble. The growth, collapse, departure and entrapment of a microbubble on a surface thus can be described. The lift forces include hydrostatic buoyancy, difference in gas and hydrostatic pressures at the microbubble base, capillary pressure and surface tension resulted from variation of circumference. The force to attach the microbubble to solid surface is the surface tension resulted from variation of circumference, which is not accounted for in literature. Adjusting the base radius to control static and dynamic behaviors of a microbubble is more effective than Bond number. Part II: Controlling states and growth of a microscale bubble (or pendant drop) in a static liquid on a surface by introducing general phase diagrams is proposed. Microbubbles are often used to affect transport phenomena in micro- and nano-technologies. In this work, a general phase diagram is provided by applying a perturbation solution of Young-Laplace equation for bubble shape with truncation errors of the second power of small Bond number. The three-dimensional phase diagram for a given Bond number is uniquely described by the dimensionless radius of curvature at the apex, contact angle and base radius of the microbubble. Provided that initial and end states are chosen, adjusting two of them gives the desired states and growth, decay and departure of the bubble described by path lines in the phase diagram. A universal three-dimensional phase diagram for a microbubble is also introduced.

This thesis deals with modelling of project teams and their behavior using the principles of system dynamics. Main goal of this thesis is to create a model using system dynamics, which will allow to simulate how projects are finished. Results from the model are going to be used to define the best possible strategy to finish a project in required time. Theoretical part of this work is composed of presentation of project management and further the thesis extensively describes system dynamics, principles of system dynamics, used diagrams and possible ways of application of system dynamics in the real world. Furthermore are described the principles and advantages of using models and specifically system dynamics models. In the practical part of this thesis is presented the created model, which allows for simulating of project team behavior based on the input from the user of the model. Model serves the purpose of finding the best possible strategy to finish the product successfully.

This diploma thesis deals with the optimization of production process at ADC Czech Republic s.r.o. Primarily, the method of Lean Six Sigma is used. The first part has a form of the literary study where individual methods used within the company are described. These are further applied in the practical part. The second part presents a brief introduction of the company including the production portfolio. The last part focuses on the practical solution of particular problems of two packaging lines aiming to increase the utilization. In the thesis, the DMAIC improvement cycle is employed.

Master’s thesis is focused on the issue of information systems. Its attention is focused on describing not only the knowledge of the basic terminology of information systems, the definition of the necessary prerequisites for development an information system within the enterprise, but also its implementation and subsequent management. The practical part of diploma thesis is based on knowledge of the theory. Its main section focuses on the realization of information system.

My diploma thesis describes a procedure of creating interactive computer software for company ISH&MSA Čerpadla a.s. in its theoretical part as well as in its practical part. It is a proposal diagram of centrifugal pumps which consists of made and nonmade pumps. After the selection of a certain pump, according to the required parameters of capacity of pump and transit height, the output of the programme is drawing of a flows characteristic, characteristics of coiled paddlewheel and curves of dissipation without any differences in whether the pump is made or not. There is an operating procedure from the initial work with data, short demonstrations from source code, computation of nonmeasured pump to the ascending flows characteristics in practical part of my diploma thesis. In theoretical part, there are explained principles that are needed for comprehension of a pump reform which are used in practical part.