55 research outputs found
Understanding the limitations of state-of-the-art nonlinear system identification approaches applied to experimental systems
No full textIn recent years, there has been a lot of focus on system identification using vibration data instead of building mathematical models based on domain knowledge. The Sparse Identification of Nonlinear Dynamical System (SINDy) is a method that has been a great tool to identify the nonlinear dynamics. Therefore, in this report, the nonlinear systems such as duffing oscillator, Single Degree of Freedom (SDoF) with friction are identified using SINDy algorithm. An impact of noise in the measurement data is studied briefly. The components used in the process of identification are smooth finite difference-based differentiator, Sequential Threshold Least Squares (STLSq) optimizer and custom candidate library. Further, a comparison is made between the numerical models and the models obtained from PySINDy. The Root Mean Squares Errors are calculated for all the cases. It is seen that SINDy is capable of identifying these nonlinearities with good accuracy.Civil Engineerin
Fantastic alterities and The Sandman
No full textThis article explores the ways in which the comics medium enhances our understanding of literary models of the Fantastic. It examines the presence and depiction of multiple worlds in Neil Gaiman’s The Sandman, with specific reference to the role of the comics medium and its denial of mimesis when creating such alterities.
It initially uses literature review to establish a contemporary working model of the Fantastic, taking as its basis the framework devised by Tzvetan Todorov, and incorporating the later work of Rosemary Jackson, A B Chanady, and Christine Brooke-Rose. It establishes the position of the Fantastic as a literary mode lying between the marvellous (supernatural accepted) and the uncanny (supernatural explained), and clarifies the distinction between the mode of the Fantastic (which encompasses various genres) and the genre itself.
The article then considers the ways in which both the form and content of the comics medium sustain the mode of the fantastic. It broadly discusses the ways in which the following factors contribute to this process:
• subject matter: fantastic events, super powers, alternate worlds
• non-realistic aesthetic: pop art, stylised visuals, fiction of fonts (invoking the tension between hand-drawn and computerised artwork or lettering)
• authorial reticence: the possibilities for surpassing or discarding narrative voice
• the role of the reader: as both interpreter and co-creator.
It then focuses more closely upon the genre of the Fantastic, establishing the ways in which this genre is opposed to both magical realism (outright fantasy) and realism (where such events are explained). It summarises the role of various qualities of the Fantastic in this regard, which include an antinomy between the natural and supernatural, author reticence, over- or under-determined language, and a defiance of absolute meaning in favour of interpretation or hesitation .
The article then proceeds to two case studies, taken from Neil Gaiman’s The Sandman: A Game of You and The Kindly Ones. The first analyses the construction of two contrasting alterities (‘The Land’ and ‘New York’) and examines the ways in which, despite initial appearances, these two worlds are both equally removed from the referent of ‘reality’. It proceeds to discuss the use made of over- and under-determined signifiers, the transformation motif, intertextuality, and the redefinition of static notions (home, gender) as fluid and undefined. It deconstructs The Kindly Ones in similar terms, considering the ways in which its triple alterities are all simultaneously validated by the text and the role of motifs such as multiple names and duplicated characters.
It concludes that, like the Fantastic, the comics medium exposes the notion of ‘reality’ as a constructed referent, which the text’s alterities comment on. The nature of the medium allows for the construction and sustenance of multiple worlds without recourse to a stable notion of reality. As the reader’s hesitation destabilises interpretation of reality versus fantasy, absolute meaning is denied. It therefore seems that comics offer what might be best described as a postmodern vision of the Fantastic
Machine learning techniques for investigating the Coulomb friction and hysteresis in structural joints: A data driven approach for monitoring non-linearity in engineering systems
No full textStructural joints influence the design strength, material requirement of a structure. Structural joints experience damping dissipation due to friction damping or hysteresis damping. Damping is often used for reducing the vibrations in a structure. However, large amount of energy dissipation leads to deterioration of the material used for constructing the joint. Hence it is important to identify the system parameters like stiffness, viscous damping, friction force as well as the hysteretic restoring force that cause the energy dissipation in the structure.For identifying the uncertain system parameters like stiffness, viscous damping and magnitude of friction force, the SINDy algorithm is extended by using stick and slip temporal constraints. This is done by segregating the data of external forcing and response of SDoF system, applying the existing SINDy algorithm and applying the sticking and slipping conditions in the time domain. The proposed Extended SINDy approach estimates the system parameters more accurately compared to the existing SINDy algorithm.For studying the hysteresis in the structural joints, a pinned column base-plate was considered in an elastic region. Further, the Dahl model with different slope parameter for each branch of moment-rotation hysteresis is employed. The correct values of parameters are estimated using the Bayesian Optimization technique. This procedure yields a functional form representing a resisting hysteretic moment-rotation behaviour in a structural joint with good accuracy.Civil Engineering | Structural Engineerin
Physiological behavior of greenhouse-grown chrysanthemum (Chrysanthemum morifolium ´’Shrek’ ´ and ´Bomber Green´) in response to the plant growth retardant B-9 and the cytokinin BAP
No full textilustraciones, diagramas, fotografías, tablasEl crisantemo (Chrysanthemum morifolium Ram) representa la tercera flor de corte de
importancia económica en el mercado internacional. En el presente estudio, se caracterizó
la respuesta de plantas de crisantemo ‘Shrek’ y ‘Bomber Green’ y la vida de florero de
tallos cortados, a la aplicación del retardante de crecimiento B-9 (daminozida) y la
citoquinina (6-benciladenina, BAP). En un primer ensayo se evaluó la aplicación de B-9,
con un testigo absoluto sin adición de B-9 y un testigo comercial (TC), usando 6
concentraciones diferentes aplicadas a los 28, 36, 44 y 52 días después del trasplante
(DDT). En un segundo ensayo, se evaluó la aplicación de la citoquinina (CK) BAP (0, 33,3,
66,6 y 100 mg kg-1
) suministrada a los 28, 36, 44 y 52 DDT. La respuesta a estos
tratamientos fue evaluada con una cuantificación de la masa seca acumulada en órganos
(raíz, tallo, hojas y flores) y cálculos de algunos parámetros de crecimiento. Se determinó
el índice de clorofilas con medidor portátil SPAD-502 en hojas del estrato bajo, medio y
superior. Se caracterizó también la duración en días de la vida en florero, inicio de
amarillamiento y grado de amarillamiento de las hojas. La aplicación de B-9 generó una
reducción en la altura de la planta. El cultivar ‘Shrek’ tuvo diferencias estadísticas (P<0,05)
en la acumulación y en parámetros de crecimiento relacionados con el área foliar. La
acumulación de masa seca fue mayor en tallos de los dos cultivares. Con aplicación de
CK, el índice de clorofila incrementó en los estratos medio y superior, mientras que, en las
hojas del estrato inferior disminuyó y se presentó amarillamiento del follaje. La mayor vida
en florero se obtuvo en tallos de ‘Bomber Green’. Los factores que promueven el
amarillamiento del follaje podrían estar relacionados con el material vegetal y la interacción
con las condiciones ambientales a las cuales se expongan las plantas durante el crecimiento y desarrollo (Texto tomado de la fuente).The chrysanthemum (Chrysanthemum morifolium Ram) represents the third cut flower of
economic importance in the international market. The present study characterized the
responses of chrysanthemum plants ‘Shrek’ and ‘Bomber Green’ to the application of the
growth retardant B-9 (active ingredient daminozide), and the addition of the citokinin 6-
benzyladenine (6-BAP) on the chlorophyll content and vase life of cut flower stems. The
first trial evaluated the application of seven concentrations of B-9 applied at 28, 36, 44 and
52 days after transplant (DAT). A second trial evaluated the application of three
concentrations of 6-BAP supplied at 28, 36, 44 and 52 DAT. Dry mass accumulation in the
various plant organs (roots, stems, leaves and flowers) were evaluated along with
calculation of some growth parameters. The chlorophyll index was determined with a
SPAD-502 portable meter in leaves of the lower, middle, and upper third of plants. Finally,
the duration in days of vase life and the onset and degree of leaf yellowing were
characterized in the two cultivars. The application of B-9 caused a reduction in plant height
and the cultivar ‘Shrek’ had statistical differences (P<0.05) in biomass accumulation and
growth parameters related to leaf area. Dry mass gain was greater in stems of the two
cultivars. With CK application the chlorophyll index increased in the middle and upper
leaves, while in the leaves of the lower third had lower values and yellowing symptoms.
The longest vase life was observed in flower stems of ‘Bomber Green’. The factors that
promote the yellowing of the foliage could be related to plant genetics and its interaction
with environmental conditions during the crop growing cycle.MaestríaMagíster en Ciencias AgrariasFisiología de Cultivo
Glass and circularity
No full textEditorialGreen Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Architectural Technolog
A Posteriori Premium Rate Calculation using Poisson-Gamma Hierarchical Generalized Linear Model for Vehicle Insurance
Get PDFThis study develops and applies the Poisson-Gamma Hierarchical Generalized Linear Model (PGHGLM) to address the challenge of determining accurate and fair premium rates in vehicle insurance. The PGHGLM models a mixture distribution for the response variable, influenced by random effects, and employs a logarithmic link function. Parameter estimation is conducted using the maximum likelihood method. However, since analytical estimation is not feasible, the numerical conjugate gradient method, specifically the Fletcher-Reeves algorithm, is utilized. The implementation of the PGHGLM uses the longitudinal Claimslong dataset, incorporating driver age as a covariate. The main contribution of this research lies in integrating a priori risk classification with a posteriori adjustment based on longitudinal claim frequency data. For datasets without covariates, trend parameters are incorporated into the model. For datasets with covariates, such as driver age, the average claim frequency is computed for each age category. Results show that posteriori premium rates increase with rising claim frequency from the previous year, with higher claim frequencies leading to larger rate adjustments in the subsequent year. Through the PGHGLM, a posteriori premium rate estimates are obtained for each age group of vehicle insurance policyholders. This study demonstrates the practical application of the PGHGLM in calculating precise premium rates. By analyzing a longitudinal vehicle insurance dataset, the model generates annual a posteriori premium rates tailored to age groups. These findings underscore the PGHGLM’s robust methodological framework and its potential to enhance premium fairness, enable risk-adjusted pricing, and better tailor insurance products to diverse policyholder profiles.
Generalized Linear Models for Loss Calculation in General Insurance
No full textIn most cases, loss in non-life insurance is calculated based on claim severity and frequency and an assumption of independence. However, in some cases, claim severity depends upon the claim frequency. This paper presents the derivation of aggregate loss calculation by modeling claim severity and frequency as the assumption of independence is eliminated. The authors modeled average claim severity using claim frequency as the covariate to induce the dependence among them. For that purpose, we use the generalized linear model. After doing parameters estimation, we will obtain the calculated loss
Influence of the partial closure of estuaries on the residual sediment transport and trapping
No full textIn this thesis the water motion and sediment dynamics are investigated in a periodically closed and opened estuary. The water motion in an estuary is mainly driven by the semi-diurnal tide with an period of 12h25m and river discharge. An example of such an estuary is the Ems-Dollard estuary. Recent observations show an increase in tidal range (height difference between high and low tide), suspended sediment concentration and the depletion of oxygen levels (consequently harming the ecosystem). A possible solution, periodically closing and opening the estuary, is investigated. The water motion in a periodically opened and closed estuary is described by the linearised cross-sectionally averaged equations which give the sea-surface elevations and tidal velocity when solved with the eigenfunction expansion method. It was found that the sea-surface elevations and tidal velocity for a periodically opened and closed estuary are again 12h25m periodic. For the sediment transport, when no overtide is considered the residual sediment transport is seaward directed if the estuary is closed at low water and landward directed if the estuary is closed at high water. The barrier location determines the magnitude of the residual sediment. When overtide is included in the forcing of the system no relation is foundbetween the direction of the residual sediment transport and the closing height and closing position. The location of the barrier and closing height both determine the magnitude of the residual sediment transport and direction. By introducing a barrier that periodically closes and opens we intended to achieve a seaward directed residual sediment transport in the Ems-Dollard estuary. The results suggest that this is not possible. Further research is needed with moreextensive models to confirm this. For future Research I recommend to extend the model to a two-dimensional model with the eigenfunction expansion method. Other possibilities may be to consider a spatial dependent erodible bed.Applied Mathematics | Applied Physic
Artificial phylloplanes: A novel tool to study parameters linked to bacterial and viral contamination of fresh produce
Get PDFEvery year, one-in-six Americans suffer from a food-related illness caused by bacteria, viruses, or parasites. Since 2010, fresh produce has been linked to seven foodborne outbreaks caused by Escherichia coli species alone. Produce surface properties, such as surface hydrophobicity and surface roughness play a key role determining the attachment of bacteria and viruses to and their removal from produce. A few previous studies have investigated the effect of surface roughness and surface hydrophobicity on the attachment and removal of bacteria and viruses from food and food contact surfaces. However, since produce surface properties undergo constant changes as a function of time and environmental factors, reports have shown inconsistent results for the same produce type with regard to bacteria attachment and removal.
Researchers have realized the need to construct artificial plant surfaces to retain the surface characteristics of natural plant surfaces during sanitation tests. A few attempts have reported the use of polymers, stainless steel, zinc substrates, or alumina to fabricate surrogate surfaces that resemble food or food contact surfaces, with varying degrees of success. Nevertheless, even the most successful one among the pervious surrogate surfaces can only replicate the topographical characteristics of natural fresh produce surfaces, but not the chemical properties of the plant surfaces. Furthermore, most of the previous surrogate surfaces lack reusability due to the nature of the fabrication material. In a microbial attachment or removal study, the surrogate surface will be subjected to mechanical forces because they need to be placed in a stomacher to do the emulation; thus, the surrogate surfaces made from soft material will be damaged. The overall goal of this study is to develop a new method for the fabrication of reusable and reproducible artificial phylloplanes that replicate the three-dimensional topological features of natural produce leaves, thus having surface hydrophobicity, roughness values, and epicuticular composition resembling those of two selected fresh produce varieties. To achieve the goal, three inter-related studies were performed.
In the first study, the effects of physiochemical characteristics, including produce leaf surface roughness, epicuticular wax composition, and produce and bacteria surface hydrophobicity on attachment/removal of E. coli K12 to/from plant surfaces was investigated. The attachment and removal of E. coli K12 was affected by multiple factors including produce genotype, produce surface roughness, and wax composition. Rougher surfaces resulted in higher attachment of E. coli and less removal. In addition, the removal of E. coli K12 was positively correlated with alkanes, ketones, and total wax content on the leaf surfaces.
In study two, a method to create polydimethylsiloxane (PDMS)-based artificial phylloplane surface to resemble the topographical, chemical, and epicuticular characteristics of ‘Outredgeous’ romaine lettuce and ‘Carmel’ spinach to a high fidelity was developed. The artificial produce leaf surfaces were utilized to study the effect of surface hydrophobicity on the attachment of E. coli O157:H7 and Listeria innocua. The PDMS- artificial phylloplanes are reusable, economical, and recyclable. They can thus be used as a platform to investigate the interactions between bacteria and produce, and to develop new or enhanced fresh produce decontamination strategies.
In study three, the newly developed artificial phylloplane surfaces were utilized to study the effect of produce leaf physiochemical characteristics on the attachment and removal of porcine rotavirus (PRV), strain OSU, and tulane virus (TV), a surrogate of human norovirus. In addition, the artificial phylloplanes were used to screen commercially available and new sanitizers and to study the use of ultrasonication as an enhancer of viral detachment in the washing step. No significant differences in attachment of PRV and TV inoculated to fresh leaves of ‘Outredgeous’ romaine lettuce and ‘Carmel’ spinach and their artificial phylloplanes were observed. In sanitation tests, the removal of virus attached to natural and artificial surfaces was virus type, sanitizer type, and produce cultivar dependent.
In summary, the newly developed artificial phylloplanes establish a platform with constant surface properties for studying the interactions between bacteria and produce leaf surfaces. The new surfaces overcome the biological variations of produce surfaces originated from changes during preharvest, transportation, and post-harvest processing/storage, which oftentimes result in inconsistent sanitation results. The newly developed artificial phylloplanes provide a faithful replication of the surface characteristics of fresh produce in that they 1) resemble the 3D topological features of natural produce leaf surfaces, 2) have a similar surface hydrophobicity, 3) have similar epicuticular chemical composition, mainly epicuticular wax composition, 4) produce a similar bacterial attachment pattern, and 5) are reproducible and reusable, including autoclave-able and compatible with stomacher.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2020-08-01The student, Sindy Palma Salgado, accepted the attached license on 2018-07-10 at 16:47.The student, Sindy Palma Salgado, submitted this Dissertation for approval on 2018-07-10 at 16:57.This Dissertation was approved for publication on 2018-07-11 at 11:22.DSpace SAF Submission Ingestion Package generated from Vireo submission #12809 on 2018-09-27 at 11:36:38Made available in DSpace on 2018-09-27T16:47:29Z (GMT). No. of bitstreams: 3
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The sustainable business model as a driver for change? : Exploring the utilization of Sustainable Business Model Innovation to master the sustainability agenda of established Austrian companies
Get PDFThe EU is driving change through the European Green Deal, with the goal of becoming the first carbon-neutral continent by the year 2050. But how do companies translate this requirement into practice? And how does business model innovation impact the corporate sustainability agenda? The research question of this thesis is: How is the Sustainable Business Model concept used in established companies in Austria? First the author clarifies the terminology related to the BM and the concept of the sustainable business model for practical use. This includes identifying key terms and attempting to categorize them. The second step is to find out how SBM is understood in practice and how it is consciously or unconsciously integrated into sustainability activities. In addition, the author explores what measures companies are taking to implement sustainability in their business and what factors facilitate or hinder this approach. Based on the findings from theory and practice, a process is proposed to help established companies to recognize sustainability as a potential and to implement it on the BM level. The potential of the company is to be built on a shared value and the core resources of the company, which is extended by the potentials of the partners and thus to be able to take a strategic, competitive market position. This process puts the cooperation of the company with external ones in the foreground and thus enables the exchange of know-how and promotes organizational learning
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