41 |
Integration av produktionsaspekter i produktutvecklingsprocessen / Integration of production aspects in the product development processCrnoja, Anna January 2022 (has links)
För organisationer att bibehålla konkurrenskraft på dagens marknad krävs en effektiv produktutveckling samt produktion, och en viktig framgångsfaktor är förmågan hos företag att integrera produktionsaspekter i produktutvecklingsprocessen. Informationsförmedling mellan de två parterna möjliggör för en mer synkroniserad utvecklingsprocess med samutvecklade produkter. Utifrån en litteraturstudie baserad på vetenskaplig forskning, samt en empirisk studie baserad på intervjuer på Scania, har arbetet har studerat hur organisationer integrerar produktionsaspekter i produktutvecklingsprocessen, samt undersöka vilka möjligheter och utmaningar som förekommer i samband med det. Studien har identifierat att det finns flera metoder för att integrera produktionsaspekter i produktutvecklingsprocessen, där kommunikation spelar en viktig roll och måste organiseras av företaget. I fall där organisationer kan övervinna diverse begräsningar, som till exempel dåliga kommunikationskanaler och långa geografiska avstånd, för att på så sätt främja en lyckad integration mellan avdelningarna, förekommer fördelar som till exempel ökad ekonomisk vinning för företaget, mindre arbetsolyckor, mindre sjukskrivningar, glada medarbetare och en nöjd kund som får en produkt i toppkvalitet. / For organizations to maintain competitiveness, efficient product development and production are a key factor, and an important success factor is the ability of companies to integrate production aspects into the product development process. Dissemination of information between the two parties enables a more synchronized development process with co-developed products. With a literature study based on scientific research, and an empirical study based on interviews at Scania, the work has studied how organizations integrate production aspects in the product development process, and investigate what opportunities and challenges arise in correlation to it. The study has identified that there are several methods for integrating production aspects into the product development process, where communication plays an important role and must be supported by the company. In cases where organizations can overcome various limitations, such as poor communication channels and long geographical distances, successful integration between departments can be established, and will result in benefits such as increased financial profit, reduction in work accidents, less sick leave, happy employees and a satisfied customer who receives a product in top quality.
|
42 |
Compara??o da an?lise de diferentes perfis de po?os pelo m?todo DFA / Comparative analysis of different profiles of wells by method DFASilva, ?talo Batista da 16 January 2014 (has links)
Made available in DSpace on 2014-12-17T14:08:54Z (GMT). No. of bitstreams: 1
ItaloBS_DISSERT_Parcial.pdf: 1092449 bytes, checksum: 84033c6935995f4df8913ea7b715a8e5 (MD5)
Previous issue date: 2014-01-16 / The study of complex systems has become a prestigious area of science, although
relatively young . Its importance was demonstrated by the diversity of applications that
several studies have already provided to various fields such as biology , economics and
Climatology . In physics , the approach of complex systems is creating paradigms that
influence markedly the new methods , bringing to Statistical Physics problems
macroscopic level no longer restricted to classical studies such as those of
thermodynamics . The present work aims to make a comparison and verification of
statistical data on clusters of profiles Sonic ( DT ) , Gamma Ray ( GR ) , induction (
ILD ) , neutron ( NPHI ) and density ( RHOB ) to be physical measured quantities
during exploratory drilling of fundamental importance to locate , identify and
characterize oil reservoirs . Software were used : Statistica , Matlab R2006a , Origin 6.1
and Fortran for comparison and verification of the data profiles of oil wells ceded the
field Namorado School by ANP ( National Petroleum Agency ) . It was possible to
demonstrate the importance of the DFA method and that it proved quite satisfactory in
that work, coming to the conclusion that the data H ( Hurst exponent ) produce spatial
data with greater congestion . Therefore , we find that it is possible to find spatial
pattern using the Hurst coefficient . The profiles of 56 wells have confirmed the
existence of spatial patterns of Hurst exponents , ie parameter B. The profile does not
directly assessed catalogs verification of geological lithology , but reveals a non-random
spatial distribution / O estudo dos sistemas complexos tornou-se uma ?rea prestigiada da ci?ncia, apesar de ser
relativamente jovem. Sua import?ncia foi comprovada pela diversidade de aplica??es que v?rios
estudos j? proporcionaram para campos diversos como os da Biologia, Economia e
Climatologia. Na F?sica, a abordagem dos sistemas complexos vem criando paradigmas que
influenciam de forma marcante os novos m?todos, trazendo para a F?sica Estat?stica problemas
de n?vel macrosc?pico n?o mais restritos a estudos cl?ssicos como os da Termodin?mica. O
presente trabalho tem como objetivo fazer uma compara??o e verifica??o dos aglomerados
estat?sticos de dados relativos aos perfis de S?nico (DT), Raio Gama (GR), Indu??o (ILD),
Neutr?nico (NPHI) e Densidade (RHOB) por serem grandezas f?sicas medidas durante a
perfura??o de po?os explorat?rios de fundamental import?ncia para localizar, identificar e
caracterizar reservat?rios de petr?leo. Foram utilizados os softwares: Statistica, Matlab R2006a,
Origin 6.1 e Fortran para a compara??o e verifica??o dos dados dos perfis de po?os de petr?leo
da Escola Campo Namorado cedidos pela ANP (Ag?ncia nacional de petr?leo). Foi poss?vel
evidenciar a import?ncia do m?todo DFA e que o mesmo mostrou-se bastante satisfat?rio no
referido trabalho, chegando-se a conclus?o que os dados do H (expoente de Hurst) produzem
dados espaciais com uma maior aglomera??o. Portanto, constatamos que ? poss?vel encontrar
padr?o espacial usando o coeficiente de Hurst. Os perfis dos 56 po?os comprovaram a
exist?ncia de padr?es espaciais dos expoentes de Hurst, ou seja, par?metro B. O perfil avaliado
n?o cataloga diretamente a verifica??o da litologia geol?gica, mas revela a exist?ncia de uma
distribui??o espacial n?o aleat?ria / 2024-12-31
|
43 |
Implementing and Evaluating Automaton Learning Algorithms for a Software Testing PlatformKhosravi Bakhtiari, Mohsen January 2015 (has links)
The Software Reliability group at KTH-CSC has designed and built a novel test platform LBTest for black-box requirements testing of reactive and embedded software systems (e.g. web servers, automobile control units, etc). The main concept of LBTest is to create a large number of test cases by incorporation of an automata learning algorithm with a model checking algorithm (NuSMV). This platform aims to support different learned automata, learning algorithms and different model checking algorithms which can be combined to implement the paradigm of learning-based testing (LBT).This thesis project investigates an existing published algorithm for learning deterministic finite automata (DFA)known as Kearns algorithm. The aimof this thesis is to investigate how effective Kearns algorithm is from a software testing perspective.Angluin’s well-known L* DFA learning algorithm has a simple structure and implementation. On the other hand, Kearnsalgorithm has more complex, difficult structure and harder implementation than L* algorithm, however it is more efficient and faster. For this reason, the plan is to implement an advanced DFA learning algorithm, Kearns algorithm[4], from a description in the literature (using Java).We consider a methodology to compare Kearns algorithm with Angluin’s DFA learning algorithm based on the master thesis of Czerny[8].The comparisonsbetween the Kearns and the L* algorithmsare based on the number of membership and equivalence queriesto investigate the difficulty of learning
|
44 |
Métodos emergentes de física-estatística aplicados a séries temporaisBATISTA, Carlos André 16 February 2006 (has links)
Submitted by (ana.araujo@ufrpe.br) on 2016-05-25T15:27:20Z
No. of bitstreams: 1
Carlos Andre Batista.pdf: 1088768 bytes, checksum: 7819bd86b2d74fe0f2599519c5bdf4cb (MD5) / Made available in DSpace on 2016-05-25T15:27:20Z (GMT). No. of bitstreams: 1
Carlos Andre Batista.pdf: 1088768 bytes, checksum: 7819bd86b2d74fe0f2599519c5bdf4cb (MD5)
Previous issue date: 2006-02-16 / The main objective of the present work was to apply recently developed in methods in physics-statistics to the time series, especifically in this work, to intervals of heart beats obtained from blood pressure signs (BP) of the sloth (Bradypus variegatus), with the purpose of identifying differences in fractality terms in the system of autonomous control related to the different situations lived by the animal along 48 hours (light-dark cycles). One tried to investigate if environmental changings may produce tendencies or have influence on the autonomous control system, using analysis multifractal methods, like Multifractal Detrended Fluctuations Analysis (MF-DFA). Due to the conditions in which the sloth BP data were obtained, that is, obtained to intervals of 15 minutes, it was necessary the adaptation of data for application of the technique MF-DFA. For validation of the adaptations, tests with humans' electrocardiograms gave us support to work with the interbeats data of sloth. The obtained results showed asignificant increasement of multifractalidade in the intervals of heartbeats of the sloth in the light cycle in relation to the dark cycle. / O principal objetivo do presente trabalho foi aplicar métodos recentemente desenvolvidos em física-estatística às séries temporais, em especial neste trabalho, a intervalos de batimentos cardíacos obtidos a partir de sinais de pressão arterial (PA) do bicho preguiça (Bradypus variegatus), com a finalidade de identificar diferenças em termos de fractalidade no sistema de controle autonômico relacionadas às diferentes situações vividas pelo animal ao longo de 48 horas (períodos claro e escuro). Procurou-se investigar se alterações ambientais produzem tendências ou têm influências sobre o sistema de controle autonômico, utilizando métodos de análise multifractal, como Multifractal Detrended Fluctuations Analysis (MF-DFA). Devido às condições nas quais os dados de PA de preguiça foram obtidos, isto é, obtidos a intervalos de 15 minutos, fez-se necessário a adaptação dos dados para aplicação da técnica MF-DFA. Para validação das adaptações, testes com eletrocardiogramas de humanos nos deram suporte para trabalhar com os dados de intervalos de batimentos cardíacos do bicho-preguiça. Os resultados obtidos mostraram que existe um aumento significativo demultifractalidade nos intervalos de batimentos cardíacos do bicho preguiça no período claro em relação ao escuro.
|
45 |
Electromagnetic radiation and Radon-222 gas emissions as precursors of seismic activityPetraki, Ermioni January 2016 (has links)
Earthquakes are amongst the most destructive of natural phenomena and have been the subject of significant research effort over many decades, to predict the onset of seismic events. Electromagnetic emissions detected prior to earthquakes provide a potential data source for seismic predictions and research suggests that specific pre-seismic electromagnetic activity can be directly related to specific earthquakes although it is still an open issue as to the precise links between these electromagnetic emissions and subsequent earthquakes. In this research, findings of the long memory or the self-organization of several pre-earthquake MHz electromagnetic time-series provide significant outcomes regarding the earthquake prediction. It is also recognised that enhanced radon gas emission has an equally long history as being associated with seismic activity. In general, several anomalous soil radon emissions have been observed prior to earthquakes and this has been recorded all over the world. The abnormal soil radon exhalation from the interior of the earth has been associated with earthquakes and is considered as an important field of research. The research reported in this thesis compared and contrasted the merits of combining electromagnetic emission data and radon exhalation data as precursors of earthquakes with the aim of enhancing earthquake prediction methodology. The findings from the long-memory analysis of radon disturbances in the soil indicated a very significant issue: the radon disturbances in the soil prior to earthquakes exhibit similar behaviour as the MHz RF disturbances of general failure. So, the radon precursors and the MHz electromagnetic correspond to the same pre-earthquake phase. Geological explanations were proposed in view of the asperity model. Persistent and anti-persistent MHz anomalies were due to the micro-cracking of the heterogeneous medium of the earth's crust which may have led the system's evolution towards the global failure. Fractal methods have been used on historical data, to investigate MHz electromagnetic time-series spectra on emissions preceding major earthquakes over the period 2007 to 2014 and the characteristics of enhanced radon emissions have been studied over the period 2008 to 2015 for seismic events occurring in the Aegean Region. It has been found that both the electromagnetic emissions and the radon exhalation data exhibit similar fractal behaviour and are associated with impending seismic activity. Hence both phenomena are relevant to earthquake predictions and should both be employed in any systematic approach to this problem as the varying geological and geographic conditions under which earthquakes can occur, might preclude one or other data from being measurable. According to the several techniques applied in this thesis, all should be employed in sequential steps, albeit the power-law spectral fractal analysis is the most significant to trace long-memory patterns of 1/f processes as those of the processes of earthquakes.
|
46 |
Market Efficiency of African Stock MarketsNumapau, Gyamfi Emmanuel 18 May 2018 (has links)
PhD (Statistics) / Department of Statistics / There has been a growing interest in investment opportunities in Africa. The net foreign direct
investment (FDI) to Sub-Saharan Africa has increased from $13 billion in 2004 to about $54 billion
in 2015. Investing on the stock markets is one of such investment opportunities. Stock markets in
Africa have realised growth in market capitalization, membership, value and volume traded due to an
increase in investments. This level of growth in African stock markets has raised questions about their
efficiency. This thesis examined the weak-form informational efficiency of African stock markets. The
aim therefore of this thesis is to test the efficiency of African stock markets in the weak-form of the
Efficient Market Hypothesis (EMH) for eight countries, namely, Botswana, Egypt, Kenya, Mauritius,
Morocco, Nigeria, South Africa and Tunisia. Since, the researcher will be testing the weak-form of the
EMH, the data to be used is on past price information on the markets of the eight countries. Data for
the eight countries were obtained from DataStream for the period between August 28, 2000 to August
28, 2015. The data is for a period of 180 months which resulted in 3915 data points.
Although there have been studies on the weak-form market efficiency of African stock markets, the
efficiency conclusions on the markets have been mixed. This problem might be due to the methods used
in the analyses. First, most of the methods used were linear in nature although the data generating
process of stock market data is nonlinear and hence nonlinear methods maybe more appropriate in its
analysis. Also these linear methods tested the efficiency of African markets in absolute form, however,
an efficiency conclusion relying solely on absolute efficiency might be misleading because, stock markets
become efficient with time due to improvements in the quality of information processing from reforms on
the markets. The researcher solved this problem of using absolute frequency by comparing the results
when the presence of long-memory in frequency and time domains of the markets were examined.
The researcher used a semi-parametric estimator, the Local Whittle estimator to test for long-memory
in frequency domain and the Detrended Fluctuation Analysis (DFA) to test for long-memory in time
domain. The DFA method is suitable for both stationary and nonstationary time series which makes
it to have more power over methods like the rescaled range analysis (R/S) in the estimation of Hurst
exponent.
Second, the researcher examined whether the markets were predictable under the Adaptive Market
Hypothesis (AMH). The researcher employed the Generalised Spectral (GS) test to examine the Martingale
difference hypothesis (MDH) of the markets. The Generalised spectral (GS) test is a non-parametric
ii
test designed to detect the presence of linear and nonlinear dependencies in a stationary time series.
The GS test considers dependence at all lags.
Third, because of the nonlinear nature in the data-generating process on the markets, the stationarity of
the market returns under a nonlinear Exponential Smooth Threshold Autoregressive (ESTAR) model was
examined. A nonlinear ADF unit root test against ESTAR and a modified Wald-type test against ESTAR
in the analysis were employed. Fourth, the self-exciting threshold Autoregressive (SETAR) method was
employed to model the returns when non-linear patterns were observed as a result of nonlinear data
generating process on the markets.
The literature on market efficiency of African stock markets has shown that variations exist in the study
characteristics. There are variations in the method of analysis, type of test, type of data employed, time
period chosen and the scope of analysis for the studies. The researcher therefore quantitatively reviewed
previous studies by means of meta-analysis to identify which study characteristics affects efficiency
conclusions of African markets using the mixed effects model.
The findings showed the presence of long-memory in the returns of the stock markets when the whole
sample was used. This made the markets weak-form inefficient, however, when the researcher tested
for the persistence of long-memory through time, there were periods the markets were efficient in the
weak-form. The memory effect was low in the South African market but high in the Mauritian market.
Furthermore, it was observed that, the returns for Egypt, which were highly predictable when the whole
data was analysed became not highly predictable when the rolling window approach of the GS test was
used. Egypt had one of the lowest percentages of the windows that had a p-value less than 0.05 after
South Africa.
The results obtained from using the non-linear unit root tests on the logarithmic price series of the
markets under study showed that, the markets were non-stationary and hence weak-form efficient under
an ESTAR framework but for Botswana. Thus the markets were weak-form efficient when analysed
using a non-linear method. This observation means that Africa’s foreign direct investment would have
been increased over the years if the appropriate methods are used. This is because, over the years,
studies on the weak-form efficiency African stock markets have ended with mixed conclusions with most
of the markets being concluded to be weak-form inefficient as a result of the use of linear methods in
the analysis. This finding, to us, has had an effect on investors commitments to Africa because the
right methodology was not employed.
iii
The findings from modelling the returns under the non-linear SETAR model showed that, the SETAR
model performs better than the standard AR(1) and AR(2) model for all the markets under study after
the non-linear patterns were identified in the returns series. The SETAR (2,2,2) model is a threshold
model, therefore, investors are able to move freely in search of higher opportunities between the low and
high regimes. Investors main aim is to make profits, hence, the threshold model of SETAR gives them
the freedom to move to a regime where the rate of returns is increasing unlike the standard AR(1) and
AR(2) linear models where there are no switching of regimes.
Finally, none of the study characteristics in the market efficiency studies was found to be significant
in efficiency conclusions of African stock markets but the indicator for publication bias was significant.
This means that there has been a change in attitude in recent years towards studies on informational
market efficiency whose results do not support the Efficient Market Hypothesis (EMH), unlike the earlier
years when the EMH was formulated and acclaimed to be one of the best propositions in economics.
It was therefore concluded that when time-varying methods are used in analysing weak-form efficiency,
the dynamics of the markets become known to investors for proper decision-making. Also, nonlinear
methods should be used in order to reflect the nonlinear nature of data capturing on the stock markets / NRF
|
47 |
A Mixed-Methods Explanatory Analysis Embracing Modularisation, Lean, Organisational Collaboration and Communications for Lead Time ReductionFlygare, Patrik, Danielsson, Thomas January 2022 (has links)
Customers' demand and more customisable products create challenges for companies that need a higher degree of flexibility in their processes to handle the variation. A modular product architecture helps companies customise their product by swapping and sharing components, simultaneously adapting mass production strategies to reduce cost and production time. This thesis aims to analyse how low volume production with high customer customisation organisation gets affected by its complex product and what aspect can reduce complexity and shorten lead time. The purpose is to identify aspects which can reduce complexity in product configurations and processes and aspects which can shorten the lead time in a configuration to the assembly process. A literature review embracing modularisation, Lean, organisation configuration, design for assembly, innovation, and value stream mapping was constructed to help explain the situation in a case organisation. An abductive approach with a mixed-method explanatory approach was performed with a value stream map, a self-completing questionnaire, and semi-structured interviews to understand the current situation. The value stream map visualised the process and explained the performance of the organisation's Machine Order to Ex-Work process, the questionnaire explained the general department’s perception of the process, and finally, the interview contextualised the perceptions. The finding was that the customer order decoupling point is positioned at the assembly's first operation and indicates that the process is order-driven. Additionally, the questionnaire and interview findings explained that different perceptions in the organisation are palpable and that thirteen themes were identified as areas of creating complexity. The work concludes to improve lead time for low volume and high customisation organisations a radical change in strategy is necessary to achieve more efficiency.
|
48 |
Ekologie, etologie a variabilita ještěrky zelené, Lacerta viridis v Přírodní rezervaci Tiché údolí / Ecology,ethology and variability of european green lizard Lacerta viridis in Natural reservation Tiché údolíChmelař, Jan January 2014 (has links)
The European green lizard, Lacerta viridis, is in the Bohemia region stated as critically endangered species. Populations in this region are located beyond the northern border of continuous range of this species and are closely related to the "riverine phenomenon", and deeply engorged river valleys. The chosen locality in Tiché údolí is a subject to a long-term conservational management aimed to strengthen and maintain abundance of the local population. This management is a direct output of a previous study of this population performed in years 1995-1997. Main goal of the presented study is to compare current population characteristics with the older study. The locality has been visited 119 times in years from 2011 to 2014. The studied population now displays higher abundance and inhabits a larger area. The author also performed a spatial analysis of the places with presence of an observed individual in order to determine and evaluate significance of the chosen abiotic factors for habitat discrimination. The results indicate that positive discrimination is based on the presence of a rock debris and a hiding place. Strongest factors towards negative discrimination were high percentages of grass and high vegetation coverage. This study also contains and discusses ecological, ethological and...
|
49 |
Radio infranationale et discursivité identitaire en milieu insulaire : Des représentations sociales aux ethnodiscours médiatiques. Le cas des Départements français d'AmériqueAntiope, Nathalie 01 December 2008 (has links) (PDF)
La présente recherche vise à questionner le système triadique que forment une identité culturelle, un territoire et un média au sein d'une aire géographique singulière : la Méditerranée caribéenne, et plus particulièrement les Départements français d'Amérique (DFA) que sont la Guadeloupe et la Martinique. L'essor de la société de l'information et de la communication n'ayant pas épargné ces départements, les mésocommunications et microcommunications, en tant qu'expressions alternatives aux phénomènes contemporains de globalisation, se présentent désormais comme des lieux de refondation, de (re)construction mais également de réenracinement identitaire. Dans cette dynamique, les médias infranationaux jouent un rôle central dans la matrice de construction identitaire et culturelle, et notamment la radio qui occupe une place centrale au sein de ces sociétés de l'oralité. En tant qu'objet social, nous soutenons l'hypothèse que la radio, à travers ses discours, participe à la matrice de figuration d'une identité mythifiée et au maintien de ce complexe fictionnel ayant une puissance symbolique, idéologique et sociale. Les interactions des dimensions médiatique, territoriale, culturelle et linguistique au sein d'une formation humaine donnée participant à l'élaboration d'un certain type d'énoncés médiatiques que nous avons identifiés comme étant des ethnodiscours ; des implicites communautaires d'interconnaissance manifestations médiatiques d'une conscience d'appartenance spécifique et des représentations sociospatiales, socioculturelles et sociolinguistiques que celle-ci sous-tend.
|
50 |
Évaluation par simulation de la sécurité des circuits face aux attaques par fauteFaurax, Olivier 03 July 2008 (has links) (PDF)
Les circuits microélectroniques sécuritaires sont de plus en plus présents dans notre quotidien (carte à puce, carte SIM) et ils renferment des informations sensibles qu'il faut protéger (numéro de compte, clé de chiffrement, données personnelles).<br /> Récemment, des attaques sur les algorithmes de cryptographie basées sur l'utilisation de fautes ont fait leur apparition. L'ajout d'une faute lors d'un calcul du circuit permet d'obtenir un résultat faux. À partir d'un certain nombre de résultats corrects et de résultats faux correspondants, il est possible d'obtenir des informations secrètes et dans certains cas des clés cryptographiques complètes.<br /> Cependant, les perturbations physiques utilisées en pratique (impulsion laser, radiations, changement rapide de la tension d'alimentation) correspondent rarement aux types de fautes nécessaires pour réaliser ces attaques théoriques.<br /> Dans ce travail, nous proposons une méthodologie pour tester les circuits face aux attaques par faute en utilisant de la simulation. L'utilisation de la simulation permet de tester le circuit avant la réalisation physique mais nécessite beaucoup de<br />temps. C'est pour cela que notre méthodologie aide l'utilisateur à choisir les fautes les plus importantes pour réduire significativement le temps de simulation.<br /> L'outil et la méthodologie associée ont été testés sur un circuit cryptographique (AES) en utilisant un modèle de faute utilisant des délais. Nous avons notamment montré que l'utilisation de délais pour réaliser des fautes permet de générer des fautes correspondantes à des attaques connues.
|
Page generated in 0.0312 seconds