Fraunhofer Chalmers Research Centre for Industrial Mathematics
Chalmers Publication LibraryNot a member yet
70439 research outputs found
Sort by
A Monte-Carlo Based Method for Calculating the Effect of Stationary Fluctuations in 1D and 2D Systems
No full textA Monte-Carlo-based method for determining the effect on the neutron flux of stationary fluctuations in 1D and 2D is proposed in this study. The cross-sections of the two-group balance equations relying on the diffusion approximation in the frequency domain are split into their real and imaginary parts, and a modified Green’s function technique is used. In this technique, the balance equations for the real part of the balance equations are mimicked with Monte Carlo using an equivalent subcritical system. The exact same balance equations are obtained for the imaginary part. The coupling between the real and imaginary parts are resolved outside of the Monte Carlo Code, taking advantage of the properties of the Green’s function. The amplitude and phase close to the point of perturbation agree well with diffusion based-codes such as CORE SIM. This method is applicable to any frequency, and any type of cross-section perturbation. The Green’s function is furthermore found to be insensitive to frequencies around and above the plateau region. Using the Green’s function at one given frequency within this frequency range has thus a negligible impact on the estimated fluctuations in neutron flux
Process Evaluation of Flue Gas Treatment for Pressurized Oxy-fuel Combustion Systems
No full textPressurized oxy-fuel combustion with carbon capture allows for fossil fuel use with low greenhouse gas emissions. In order to avoid corrosion and emission of harmful species other impurities in the pressurized flue gas should be minimized. There is therefore an interest in the potential of simultaneous NOx and SOx removal by absorbtion into water under high pressure conditions. The treatment alternatives for the resulting liquid solution from such an absorption process is the main focus of this thesis. The thesis compares the experimental work by Stanger et al. with the detailed reaction mechanism developed by Ajdari et al. through modelling [2], [1]. The model is validated by the experimental work and is thereafter used to evaluate the behaviour of the liquid, which was not measured during the experimental work. The results show that releasing the liquid phase into a waste water pound would result in almost 40% of the nitrogen molecules being released as N2O to the air, which is not desired as N2O is a powerful greenhouse gas. It was also found that isolating the liquid phase would further increased the N2O formation. TheliquidphasealsohasalowpHvaluewhichneedstobetakenintoconsideration. OvertimeitwoulddecreasethepHvalueinthewastewaterpound. LowerpHvalue would also lead to increased N2O formation. Use of a buffer solution to keep the pH value in the waste water pound stable could be a potential solution
Evaluation of poisonous effect of Fe, K and P on deactivation of NiMo alumina catalysts during HDO of Stearic acid
No full textVilka kvaliteter värdesätter boende i sitt bostads- och närområde? En benchmarkingstudie gjord för att lyfta de kvaliteter som bör beaktas vid utveckling av framtida bostadsområden
No full textDevelopment and evaluation of an in vitro cardiovascular model for determining impact of genetic variability in calcium handling on drug-induced cardiotoxicity
No full textCardiotoxicity is evaluated throughout the process of drug discovery and development and is a leading cause of drug attrition during clinical trials. One of the major challenges includes the understanding of differential pharmacology responses in healthy and disease states. This can be improved by the development of human in vitro models and consideration of genetic variability in patients. In this thesis, a human induced pluripotent stem cell (hiPSC) line was developed with a heterozygous single nucleotide polymorphism (SNP) rs3766871 (G1886S) within a calcium handling gene, RYR2. This SNP is the second most common heterozygous SNP within RYR2 and has been associated with cardiac diseases. The SNP line was obtained by reverse transfection of hiPSCs using CRISPR/Cas9 and was validated by Sanger sequencing. Furthermore, an existing hiPSC line with a heterozygous knock-out within RYR2 was evaluated in this thesis. The heterozygous knock-out hiPSC line mimics the partial reduction of RYR2 expression observed in aging and heart disease. This line was differentiated into cardiomyocytes and characterized by FACS, ICC and Western blotting. In addition, impedance-based measurements were conducted as a surrogate of contractility to obtain functional data of amplitude and beat rate of the cardiomyocytes. Differentiation of these hiPSC lines into cardiomyocytes, followed by drug treatment, will allow the hiPSC-derived cardiomyocytes to act as in vitro cardiovascular safety models of genetic variability. This can help understanding of the impact of genetic variability and its role in drug-induced cardiotoxicity
Thermodynamic Assessment of a Deep Geothermal Heat Pump System
No full textCurrent geothermal energy exploitation is confined to porous, water saturated sedimentary rock. Excluding a few small scale industrial and research complexes, little progress has been made to reach the underlying crystalline bedrock, called hot dry rock(HDR).Thepotentialofthisresourceisconsideredtobeabundantandfaroutweigh the standard geothermal source in sedimentary bedrock utilized today. The focusofresearchhassofarbeenin"engineered"HDR,meaninginsomewaycreating a fracture system, through which to circulate water, in the otherwise impermeable bedrock. However, creating this fractured network is a perilous enterprise in several ways. In experimental drilling there have been issues with fluid leaks, induced seismic activity and flow short circuits among others. It is of interest to investigate alternatives in extracting this energy.
Thisthesishastheambitiontoinvestigateaclosedloopgeothermalsystem,consisting of two boreholes connected at a depth of 3500 m in the crystalline bedrock. A modelwasbuiltusingCOMSOLMultiphysics5.3. Therockpropertiesweredefined in a way common to Sweden and a heat pump is considered to be connected to the system, allowing for a constant temperature of the fluid returning to the surface. The purpose of the study was to discern which parameters that were affecting the energy extraction and how. With that goal in mind, fluid flow, incoming fluid temperature, borehole radius and thermal conductivity of the crystalline bedrock were alternated in a series of simulations. Fluid flow and incoming fluid temperature are operational phase values and are the only conditions which can be altered after construction of the system. Borehole radius has a strong impact on drilling cost. The thermal conductivity of the bedrock is a site specific value and changing this exposes the impact of more or less preferable subsurface conditions. The results shows that the convection in the boreholes were more than adequate to saturate the heat exchange with its surroundings. Limiting factors proved to be the temperature gradient between borehole and bedrock, together with rock thermal conductivity. The high thermal inertia of the bedrock, which signifies how slowly the temperature of a section of rock reaches that of its surroundings, and the relatively low thermal conductivity failed to supply adequate heat, resulting in a rapid decline in energy extraction, in the first few years of operation. Thus the heat penetration in the bedrock limits the possible thermal power output
Tool Availability at a Supplier to the Semiconductor Industry Development of a Supply Chain Operational Data Store
No full textThis research investigates a tool management problem at a large supplier to the semiconductor industry. The problem revolves around shortages of tools used for system installations at
customer sites. The research starts with a literature study, where findings on tool management
and tool unavailability from academic journals and books are integrated with a standardised
logistics concept for root cause analyses, in order to find root causes for tool shortages. The
result is a theoretical Cause & Effect framework, consisting out of eight root cause categories:
maintenance, logistics, inventory planning, project planning, organisational structure, human
factors, data management and knowledge management. The literature framework is then used
to structure an empirical investigation at the company. In this study, qualitative information
from semi-structured interviews and a workshop are triangulated with quantitative data analyses to develop a Cause & Effect diagram for the company. Then, a decision matrix is used to
select the most important root cause category to address. Consequently, a solution is developed
in this selected root cause category: data management. This solution takes the shape of an
Operational Data Store (ODS). The ODS’ purpose is to gather, store and present data that can
be used for insights regarding daily operations. In this project’s case the specific purpose was
to provide increased visibility of the supply chain, to prevent stock shortages of tools. The construction of this solution is based on daily extractions of input data on tools from databases, an
ERP system and unstructured data spread across the supply chain operations. Once gathered,
data is cleaned, merged, sorted and stored for analysis. For reporting of stock shortages data is
presented in a spreadsheet format where tools affected by stock shortages within the coming 4
months are displayed in an interactive dashboard. These reports improve daily operations for a
team within the supply chain operations department at the company, by providing an increased
planning capability and thus a better operational outlook
Unlocking Value with Supplier Relationship Management Practices A case study of how to utilize SRM as a competitive tool
No full textSupplier Relationship Management (SRM) is treated as a strategic and holistic
approach in order to manage suppliers that are critical or important to the
business. The purpose of SRM is to have a long-term relationship where mutual
growth and increased value can be achieved. A case study was performed at a
Swedish manufacturing company, where 13 qualitative semi-structured interviews
were conducted. The purpose of the study was to investigate how SRM can
empower the purchasing and supply management in a global manufacturing
company. In order to do so, the current state of SRM operations as well as the
best practice of tools and processes from literature was identified. The study was
conducted in order to provide improvement areas and suggestions of how the case
company can generate additional value and gain process efficiency from SRM
activities.
The findings synthesize that SRM concern five key areas that are interrelated and
needs to be worked with as a whole in order to succeed with SRM practices. The
five areas that respectively consist of several tools and managerial implications are
Holistic Approach to SRM, Segmentation of Suppliers, Relationship Management,
Performance Measurement, and Supplier Development. The result of the master
thesis shows that there is a great potential of implementing SRM in the case
company. Many things can and need to be done in order to unlock value. A
starting point is to follow the nine recommendations that were suggested in the
end of this report which that concludes the results of how SRM can empower the
purchasing and supply management in the company. The recommendations regard
the following areas: Orientation, goals and vision, Coordinating purchasing,
Segmentation, Governance structure, Managing relations, Key Performance
Indicators, Review meetings, Procure-to-pay process efficiency and Internally
follow up SRM