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Production Plan Forecasting on Limited Dataset
No full textForecasting production plans with limited data is a significant challenge, especially
for smaller firms or new products with short production histories. This
thesis aims to predict actual production outcomes based on historical data and
to understand the relationships between and connect planned and executed
production volumes. By exploring various forecasting approaches, including
ARIMA and Long Short-Term Memory (LSTM) networks, the study focuses
on methods designed to perform well with smaller datasets. The research employs
a hierarchical model architecture that decomposes the forecasting task
into three components: production forecasting, quarterly mapping, and unfolding
to a monthly plan estimate. The models are evaluated against baseline
strategies, including naive predictions and basic LSTM and ARIMA models.
Results show that the proposed hierarchical models outperform baseline models,
capturing the general behavior of the data more effectively. The deep
learning-based model excels at capturing extremes in the time series, while
the regression-based model provides stable and accurate forecasts. However,
the models struggle with highly erratic production plan patterns, indicating
the need for further refinement. This thesis contributes to more robust and
scalable production planning solutions for data-constrained environments, offering
valuable insights for both academic research and practical applications
Aerodynamisk optimering av ogivala vingplanformer för överljudsflygplan. Genom digital design och strömningssimulering
No full textÖverljudsflygplan är flygplan som färdas med en hastighet snabbare än ljudets. Det historiskt mest framgångsrika kommersiella överljudsflygplanet var fransk-brittiska Concorde. En ny aktör inom området är amerikanska Boom Supersonic som utvecklar
ett konceptuellt överljudsflygplan, Boom Overture. Det potentiella återinförandet av överljudsflygplan understryker vikten av aerodynamisk analys inom detta område, vilket utgör det övergripande målet för detta projekt. Vidare syftar arbetet till att undersöka den aerodynamiska prestandan, huvudsakligen karaktäriserad av glidtalet, för ogivala vingplanformer vid olika svepvinklar. En digital modell av Concorde används som utgångspunkt och omdesignas med inspiration av Boom Overture.
Concorde-modellen används även som referens för att utvärdera flygplansmodellernas prestanda. Nya modeller skapas i ett parametriserat designverktyg OpenVSP och simuleras i mjukvaran STAR-CCM+, i Overtures ämnade marschfart. Resultaten visar, vid jämförelse mellan modellerna, att den aerodynamiska prestandan varierar med olika ogivala vingplanformer. Diskussionen mynnar ut i att förändringar i utformning av den ursprungliga Concorde-modellens vingplanform, fokuserat på minskning av svepvinkeln, medför en förbättrad aerodynamisk prestanda vid lägre hastighet
Investigation of Disc Cavity Sealing Efficiency Using CFD
No full textThe wheelspace cavity between a stator and rotor disc in gas turbines are prone to ingestion of hot gases which threatens the lifetime and safe operation of the turbine. Traditionally, pressurized cooling gas known as, Purge gas, is bled from compressor stage to seal the cavity. The influence of purge - mainstream density ratio (DR), plays a vital role in efficient sealing of the cavity and holds significant practical implications for future engine designers.
Building upon prior experimental tests performed at KTH University in collaboration with Siemens Energy AB, the thesis primarily investigates the influence of this DR using CFD simulations. The investigation is carried out at design point of 10540 RPM (Cf = 0.35) for three purge flow rates 0.5%, 1.0%, 1.5% (Φ0 = 0.025, 0.050, 0.075) of main annulus mass flow. The tested purge gases are Air (DR =1) and Argon (DR = 1.38). The simulations are performed in Ansys CFX with increasing modeling complexity starting from steady state RANS to URANS and hybrid RANS- LES model, SBES. Further, a comparison of computational domains, single passage and 51◦ sector domain was also evaluated.
The results highlight the importance of sector domain over single passage domain and the need for URANS simulations to capture the unsteady ingress phenomenon.
The ingress is evaluated using the non-dimensional variable, Sealing Effectiveness, at
various radial locations. Regardless of the purge gas, an improved sealing is observed for increasing purge flow rates and for decreasing radius, as expected. Validation of CFD predictions showed a good agreement for Air (DR =1). While for Argon
(DR = 1.38), an increased sealing is predicted directly contradicting experimental conclusion. This discrepancy was attributed to the seed gas concentration level (1% CO2) used in the experiment resulting in overestimation of ingress.
For the low purge flow rate Φ0 = 0.025, regardless of purge gas a poor agreement was observed owing to the slow convection rate. While a longer simulation run performed using SBES showed relative improvement, the case still warrants further investigatio
Impact of Non-Square Modulation Formats on Multi-Layer Error- Correction Systems
No full textThis work presents a set of algorithms for integrating non-square modulation formats
with multi-layer forward error-correction (FEC) systems. This was done to
improve the adaptive coding and modulation (ACM) capabilities of Ericsson’s nextgeneration
digital signal processing (DSP) product. Specifically, support for cross-
(X) quadrature amplitude modulation (QAM) formats with 9 to 19 bits per symbol
was implemented. This was achieved while respecting limitations imposed by the
multi-layer FEC, consisting of low-density parity check and Reed Solomon errorcorrecting
codes. The main contributions were made to the symbol mapper and
demapper as well as the most significant bit decoders.
The algorithms were implemented in hardware using high-level synthesis, with the
target platform being a field-programmable gate array (FPGA). Testing on the
target FPGA was performed using a digital loop and an internal noise generator to
produce bit error rate (BER) vs. signal-to-noise ratio (SNR) curves.
The results displayed a 1 dB SNR gain when switching from a higher-order square
QAM format to a lower-order X QAM format with higher code rate. Since these
two options provide the same capacity, it implies that it is more beneficial to reduce
modulation order to improve BER performance compared to increasing FEC
overhead when channel conditions degrade. Hence, the implementation of X QAM
formats has the potential to improve the ACM flexibilty in Ericsson’s DSP product,
with only a small increase in hardware usage
Frihamnskyrkan - The evolution of the Smyrna congregation
No full textThe model shows the evolution and growth of the Smyrna congregation in Gothenburg from 1923 until today. Starting with its first assemblies in an apartment in the Arbetareförenings Hus, a now demolished building on Järntorget, the church moved to a building addition close to Hagakyrkan. This building is used as a concert hall. Two years ago the Smyrna congregation finished its own building in Frihhamnen and has since then been also visibly independent
No longer mine: Repurposing the Tuolluvaara mine
No full textTechnological advances in the deindustrialization era have significantly
impacted the mining industry, whose legacy of environmental
degradation from excessive extraction still casts a shadow over many
places around the world. One such place is Kiruna, the backbone of
the thesis, where mining actions have led to the city’s partial relocation
of many remnants of great heritage value left behind – abandoned
mines. One notable example is the Tuolluvaara mine, which hosts two
rare mining towers that stand out due to their historical and visual significance.
This thesis explores the future role of the Tuolluvaara mine
in Kiruna, proposing a strategy for repurposing its premises.
This project follows the concept of continuity, based on the theory of
Solà-Morales, to prevent architectural practices from becoming an
aggressive act in the transformation of the postindustrial area. This
approach applies both to the transformation of buildings and the land
they occupy, paying attention to heritage and history. Grounded in
theories of abandoned and decayed architecture as palimpsest, terrain
vague and collective memory, the design becomes an interplay between
the past and the present. A phased transformation is developed
to ensure gradual public access and integration, using the concepts of
conversions for site’s premises alteration.
The design considers the significance of the heritage buildings, but
also the insignificance and instability of the ground that they are
standing on - a messy and haphazard result of the deposition of excavated
masses from previous mining activities as well as of the piling
up of the soil from the construction of Kiruna’s new city centre. The
project includes phytoremediation of the wasteland and separating
it from public access until it regenerates while the buildings present
on site are transformed into open-plan public spaces and adapted for
a multifunctional implementation called a rotational programme. In a
space defined by its users themselves, the architect’s task is to establish
a versatile framework capable of adapting to various scenarios as
a response to the constantly changing challenges of the city’s relocation.
The study proposes solutions created on the layered example of
Kiruna that could be applied to other cities facing similar challenges
Bärplansbåt - Från koncept till självreglerande prototyp
No full textDenna kandidatuppsats syftar till att utveckla en självreglerande bärplansbåt, med
ambitionen att vidareutveckla en tidigare prototyp inom samma område. Målet har
varit att ta fram en modell som genom praktisk testning och analys kan bidra till
framtida forskning inom bärplansteknik.
Bärplan har länge varit en känd teknik, men dess tillämpning har begränsats av
komplexa och kostsamma reglersystem. I takt med ökad elektrifiering inom sjöfarten
har intresset för bärplansbåtar vuxit, eftersom tekniken möjliggör betydande
reduktion av vattenmotstånd och därmed ökad energie!ektivitet, vilket är särskilt
relevant för eldrivna båtar med begränsad räckvidd.
Systemet består av flera delsystem: skrov, vingdesign, vingkonfiguration och ett
kontrollsystem. Kontrollsystemet, implementerat med ArduPilot, reglerar elektriska
komponenter samt båtens stigning och rullning. Vingkonfigurationen består av
en större främre vinge för huvudsaklig lyft och rollkontroll, och en bakre vinge för
pitchstyrning. Skrovet är baserat på en tidigare design framtagen för bärplansfärjor.
Systemets funktionalitet verifierades genom ett antal fälttester, där justeringar genomfördes
mellan testen. Resultaten visar att båten kan upprätthålla stabil flygning
över vattenytan, vilket innebär att projektets mål uppnåddes.
Det mest framträdande förbättringsområdet är implementeringen av en tillförlitlig
höjdsensor. Den sensor som användes under testerna visade sig vara otillräckligt
noggrann för robust höjdreglering, vilket påverkade systemets prestanda under vissa
förhållanden
Design and Development of a Steer-By-Wire Hand-Wheel Actuator
No full textThis bachelor's thesis, conducted at Chalmers University of Technology in collaboration with Volvo Cars, explores the development of a Steer-By-Wire steering column, a system designed to replace traditional mechanical steering connections with an electrically actuated alternative. The study investigates the challenges of integrating a torque feedback device into the steering column while juggling several requirements and wishes, ensuring compatibility with existing vehicle cabin constraints. Through an extensive patent and market investigation, multiple design solutions were generated and systematically evaluated using elimination by several matrixes. The final concepts were developed in CAD and underwent testing to ensure compliance with the requirement specification. This thesis contributes insights into the optimization of steer-by-wire systems, offering potential improvements in driver comfort, maneuverability, and space efficiency. The study shows that the implementation of a steer-by-wire hand-wheel actuator is possible in the current Volvo 40-series with only minor modifications. However, additional design changes may be required for integration into other vehicles
Global scheduling of real-time tasks on multiprocessors based on priority promotion
No full textWith the widespread deployment of intelligent embedded systems across various
application scenarios, the processing capabilities and scheduling strategies of singleprocessor
platforms are increasingly unable to meet the growing computational demands
of real-time tasks. To host more and more functions with additional processing
requirements and stricter real-time constraints, multiprocessor platforms are
attracting growing attention and adoption. However, scheduling real-time tasks on
multiprocessor platforms still faces many challenges.
One major challenge is how to assign priorities in an optimal way for scheduling
on multiprocessors. There are many methods for assigning fixed priorities to tasks
in multiprocessor systems, but the optimal method is still unclear, and some tasks
cannot be scheduled feasibly under fixed-priority assignments. To overcome the
limitations of fixed-priority scheduling, it becomes necessary to introduce some form
of dynamic priority. Although the schedulers under dynamic-priority may perform
better in terms of schedulability, they are significantly more complex to implement
than the schedulers under fixed-priority. This leads to another challenge: how to
make a compromise between static and dynamic priority behaviour?
Dual-priority (DP) scheduling provides a new approach to balance between
pure fixed-priority and full dynamic-priority scheduling strategies. In dual-priority
scheduling, each task is assigned two priorities: an initial priority and a promoted
priority. The task begins execution with the initial priority, and after a fixed duration,
which is called priority promotion time, its priority is elevated to the promoted
priority. However, to the best of our knowledge, there has been no prior research
on applying DP scheduling to multiprocessor platforms. This thesis focuses on the
study of global scheduling with priority promotion in multiprocessor systems and
proposes a DP scheduling algorithm for multiprocessors, along with two tests to
verify schedulability.
Furthermore, with a priority assignment algorithm known as Audsley’s optimal
priority assignment, we develop a hybrid algorithm where a subset of the tasks
will have pure fixed priority, and each of the other tasks will have two priorities:
one before the priority promotion point(PPP) and one after the PPP. We have
evaluated the proposed test using extensive simulation experiments, and the results
demonstrate that the proposed test performs well compared to the existing test
Folke: En bevisredigerare för naturlig deduktion
No full textDenna rapport introducerar Folke, en bevisredigerare för naturlig deduktion för förs ta ordningens logik. Logik tillhandahåller ett ramverk för formellt resonerande där
man konstruerar nya påståenden utifrån initiala påståenden som kallas premisser.
Ett bevis är en korrekt formulerad sekvens av påståenden som utifrån givna pre misser når en önskad slutsats. Folke var utformad för att hjälpa studenter i logik
att formulera och verifiera sina bevis. Tidigare mjukvarulösningar har en tendens
att vara svåranvända och ointuitiva för nybörjare på grund av deras komplexitet.
För att bemöta detta har Folke utvecklats med fokus på användarvänlighet, med ett
interaktivt och nybörjarvänligt gränssnitt med tydliga felmeddelanden. Programmet
har implementerats i Haskell, och användargränssnittet har byggts med hjälp av det
komponentbaserade GUI-biblioteket Monomer. Folke distribueras som ett program
tillgängligt för Linux, Windows och Mac OS. Framtida förbättringar kan inkludera
ett hjälpsystem för bevissteg, förbättrad tolkning för mer informativa felmedde landen samt en användarstudie för att vägleda fortsatt utveckling och identifiera
eventuella buggar