The thesis work investigates the possibility of replacing the Body-In-White (BIW) sections used in a physical test with a fixture. Volvo-cars perform several sub-system tests on its car components taken from various car models for different issues. Squeak and Rattle in Cockpits is one such important phenomenon investigated through its sub-system tests. Currently, the Body-in-White (BIW) sections taken from car body are used in holding the cockpits for Squeak and Rattle physical testing on a vibrating rig, the idea is to design a fixture that can replace these BIW sections for the test. Additionally, it is ensured that the fixture is designed to accommodate a variety of cockpits through the flexibility in its structure. Models from two different car segments were considered for performing the thesis. The development process started by researching the theory behind squeak and rattle along with investigating the important design parameters which would determine the requirements on the fixture. This is followed up with benchmarking the parameters and a physical test which would help later in comparison and evaluation of fixture performance against the BIW. The result from benchmarking were then used for topology optimization in obtaining a material layout to provide a basis for fixture design. Then, a basic CAD model is generated which is adapted to provide flexibility using Aluflexmechanisms. The final design comprises of a sufficiently rigid main structure made of hollow steel beams upon which Aluflex mechanisms are attached to provide flexibility in accommodating a variety of cockpit models. The fixture is analyzed and evaluated by comparing with benchmarked data. With the thesis, a fixture with generic (flexible) features which is manufacturable has been designed. It was concluded that at its current stage it cannot completely replace the BIW since the fixture is performing better than BIW in some respects and failing to conform to the requirements in others. The possible reason for the fixture failing to meet the requirements in the few aspects has been explored. As future work, it was proposed to explore into stiffness varying mechanisms (spring mechanisms) that could alter the stiffness requirements on the fixture as per the cockpit used for testing. It was also suggested to look for alternatives to Aluflex which would provide better stiffness at the connection points. Further, it was suggested to look for alternatives in the design concept which would avoid the connection part in extending too much away from the main structure thereby retaining high stiffness at the connection point.

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This thesis highlights one of the most significant concerns that has preoccupied drivetrain engineers in recent times, namely drivetrain clonk. Clonk is an unacceptable audible sound, which is accompanied by a tactile drivetrain response. This may occur under several different driving conditions. Many drivetrain NVH concerns are related to impact loading of subsystems down-line of engine. These concerns are induced by power torque surge through engagement and disengagement processes, which may propagate through various transmission paths as structural waves. The coincidence of these waves with the acoustic modes of sub-system components leads to audible responses, referred to as clonk. The approach usually undertaken and reported in literature is either purely theoretical or constitutes experimental observation of vehicle conditions. A few research workers have reported rig-based investigations, but not under fully dynamic conditions with controlled and reproducible impulsive action. The research reported in this thesis combines experimental and numerical investigation of high frequency behaviour of light truck drivetrain systems, when subjected to sudden impulsive action, due to driver behaviour. The problem is treated as a multi-physics interactive phenomenon under transient conditions. The devised numerical method combines multi-body dynamics, structural modal analysis, impact dynamics in lash zones and acoustic analysis within an overall investigation framework. A representative drivetrain system rig is designed and implemented, and controlled tests simulating driver behaviour undertaken. The combined numerical predictions and experimental noise and vibration monitoring has highlighted the fundamental aspects of drivetrain behaviour. Good agreement is' also found between the detailed numerical approach and the experimental findings. Novel methods of measurement such as Laser Doppler Vibrometery have been employed. Simultaneous measurements of vibration and noise radiation confirm significant elasto-acoustic coupling at high impact energy levels. One of the major finds of the thesis is the complex nature of the clonk signal, being a combination of accelerative and ringing noise, with the latter also comprising of many other lower energy content as observed in the case of transmission rattle and bearing-induced responses. Therefore, the link between rattle and clonk, long suspected, but not hitherto shown has been confirmed in the thesis. Another major find of particular commercial interest is the insignificant contribution of torsional damping devices such as dual mass flywheels upon the accelerative component of the clonk response.

L'objectif de cette étude est de caractériser le bruit de graillonnement des boîtes de vitesses automobiles, qui résulte des chocs entre les pignons au niveau des rapports non engagés, sous l'effet des fluctuations de vitesses imposées par le moteur. Outre les paramètres de conception de la boîte de vitesses et les conditions de fonctionnement, les paramètres qui gouvernent la réponse dynamique des pignons fous sont les couples de traînée et les caractéristiques des contacts qui gouvernent les chocs entre dents. Un modèle numérique non linéaire a été élaboré pour caractériser la réponse dynamique d'un pignon fou. Il permet d'identifier le seuil d'excitation au-delà duquel le phénomène de graillonnement apparaît et de qualifier la très grande diversité de comportements dynamiques susceptibles d'être observés, en fonction du niveau d'excitation adimensionnée, du jeu de denture et du coefficient de restitution des chocs entre dents. Les paramètres inconnus ont été identifiés expérimentalement, grâce à l'exploitation d'un banc d'acyclisme et l'implémentation de codeurs optiques sur les pignons menant et fou. Des essais en réponse libre amortie ont permis de discriminer les différentes sources de dissipation(roulements, palier du pignon fou, barbotage, etc.) et de valider les modèles permettant d'identifier le couple de traînée s'exerçant sur chaque pignon fou. D'autres essais en régime de fonctionnement stationnaire ont permis de décrire le coefficient de restitution des chocs entre les pignons, sa dispersion et sa variation avec la vitesse d'impact. Les mesures effectuées sous une excitation maîtrisée ont permis de caractériser le comportement dynamique du pignon fou et de valider les hypothèses retenues et les résultats numériques obtenus par le modèle non linéaire, recalé à partir des paramètres préalablement identifiés. Enfin, l'analyse du transfert entre les impulsions générées au niveau des pignons et la réponse vibratoire du carter a permis d'évaluer expérimentalement et numériquement le critère qui qualifie le bruit de graillonnement rayonné par la boîte de vitesses. La mise en oeuvre du modèle numérique permet d'analyser l'influence des paramètres de conception de la boîte de vitesses et de proposer des solutions qui minimisent le graillonnement, pour l'ensemble des rapports de la boîte et des conditions de fonctionnement.

Les couples d'engrenages présents dans les boîtes de vitesses automobiles sont une source de bruit importante à prendre en compte et à maîtriser. L'acyclisme du moteur observable en entrée de boîte a notamment pour conséquence de provoquer des impacts entre les dents des engrenages non chargés, à l'origine du bruit de grenaille. Ce travail de thèse s'intéresse aux cas de grenaille dits périodiques, dont l'apparition et la sévérité dépendent, entre autres, des conditions de fonctionnement régime/charge. Pour détecter la présence et quantifier la sévérité de ce bruit, il est nécessaire de construire des indicateurs pertinents et dédiés, où il est particulièrement intéressant de conserver la dualité des informations temporelles (relatives aux voies de transfert des phénomènes vibratoires) et angulaires (relatives aux cycles de la machine) mesurées sur des boîtes en montée de régime. Une extension de l'approche cyclostationnaire classique est ainsi exploitée et la cohérence spectrale ordre/fréquence est utilisée afin de définir un indicateur de sévérité du bruit de grenaille. Deux campagnes d'essais ont été réalisées afin de valider la pertinence de cet indicateur, utilisant un banc d'essais qui permet d'imposer des montées en régime et de générer un acyclisme. Dans la première campagne d'essais, un pignon fou est instrumenté à l'aide d’un codeur optique afin de mesurer la vitesse relative pignon fou/pignon menant qui est utilisée comme référence pour détecter l'apparition des impacts. La comparaison avec l'indicateur proposé, calculé à partir du signal vibratoire d'un accéléromètre positionné sur le carter de boîte, démontre sa capacité à détecter effectivement des chocs. Des sessions d'écoute ont été organisées afin de comparer le ressenti d'auditeurs qualifiés pour faire des évaluations subjectives à l'évolution des valeurs données par l’indicateur, à partir d'une seconde campagne d'essais. Cet indicateur apparaît représentatif du ressenti des auditeurs. Une fois la grenaille détectée et quantifiée globalement en intensité, il est intéressant d'extraire sa composante du signal global mesuré. Pour cela, une extension du filtre de Wiener cyclique pour des signaux cyclostationnaires angle/temps est proposée. Le signal extrait étant supposé être généré uniquement par les impacts produisant le bruit de grenaille, les impulsions extraites sont exploitées afin d'estimer la fonction de transfert entre les points d'excitation et le capteur localisé sur le carter de boîte. Cette fonction de transfert est comparée à celle obtenue par une seconde méthode, également développée dans le cadre de cette thèse, qui consiste en une extraction de la partie déterministe de l'excitation à l'aide d'un filtre en peigne dans le domaine des ordres, puis en une identification aveugle de la réponse impulsionnelle dans le domaine cepstral. / The improvement of the engine noise emissions causes the emergence of new sources which were previously masked, like gearbox noises. Because of the engine acyclism some impacts can appear between the teeth of unloaded gears. Those impacts generate the so called rattle noise which is a current problem for car manufacturers. This work is focused on periodic cases of rattle noise. Their appearance and their level depend on operating conditions. In order to propose a specific detection indicator it is particularly useful to exploit the angle/time duality from measures in non-stationary conditions: the angle domain is linked to the periodicity of the impacts while the time domain is linked to their nature. An extension of the cyclostationary approach is thus exploited and the order/frequency spectral coherence is used to define a severity indicator of rattle noise. The validation of this indicator is obtained from measurements. For a first level of validation, a loose gear has been instrumented with an optical encoder in order to measure the relative velocity between this loose gear and the driving gear. The comparison with the proposed indicator shows its ability to effectively detect the impacts. For a second level of validation some listening sessions have been organized. The evolution of values of our indicator appears in accordance with the feeling of the listeners. After the detection of rattle noise it is interesting to extract its contribution from the measured signal. An extension of the cyclic Wiener filter is thus proposed for angle/time cyclostationary sources. The extracted signal being supposed only produced by impacts, the extracted impulses are then exploited in order to estimate a transfer function. This transfer function is compared with the other one obtained by a second method, also developed in this work. This method exploits the non-stationary regime and proposes a blind identification with cepstrum.

Background In the context of booming e-commerce and associated logistics flows, there is a considerable challenge to support the future of volumes, specifically more towards home deliveries by logistics service providers (LSP). There are means of addressing this challenge by identifying the key factors that influence consumer behaviour and lead to better adoption by meeting their convenience through right self collection end points setups thus decreasing the logistics costs, meeting sustainability targets and also efficiencies for logistics service provider operations. Purpose The purpose of this study is to study and investigate the convenience factors of self-collection endpoints and associated levels that influence consumer preferences for logistics services to use self-collection last-mile endpoint in Sweden and also associate with observed behaviour across different demographic segments. Methods For research, quantitative research was done using conjoint analysis. Data was collected using a questionnaire sent in Google forms from volunteers, designed through an orthogonal designed based profile to rate the relevance and interest it generated. Results were based on 161 respondents' feedback on 16 such profiles (autogenerated in the SPSS platform). Analyses on existing historical parcel data of the logistics service provider along with the demographic data to build decision-tree models which supports determining the crucial attributes which influence home deliveries and also identify the potential site for trialability by LSP to support better decision-making aligned with the new Innovation diffusion into usage. Conclusions The research has shown that the collection distance is the most crucial convenience factor which can drive/steer consumers to use self-collection endpoints by being relevant in the context of convenience factors to be considered as an alternate to home delivery, followed by handling time. Respondents were willing to compromise on home deliveries if distance was within their expectations, such as <300m from the study conducted. During the thesis work, decision-tree models have also been developed, which has shown relationship/dependency between demographics to different delivery methods like home vs. service points across different geographies and factors influencing it. It has been further observed that different influencing attributes play a significant role across geographical type of delivery locations, such as urban, sub-urban volume data.

The current study focuses on the vascular cambium and the reiterative formation of phloem fiber bundles in cotton stems. The role of the TDIF-PXY-WOX pathway was examined in regulating cambial activity and the differentiation of phloem fibers. A study was conducted to identify and characterize the cotton WOX family genes, focusing on WOX4 and WOX14, aiming to identify and analyze their phylogenetic relationships, tissue-specific expression profiles, functional roles, and metabolic consequences. Through a sequence analysis of the Gossypium hirsutum genome, 42 cotton loci were identified as WOX family members. GhWOX4 exhibited a close homology to 7 loci, while GhWOX14 displayed homology with 8 loci. Tissue-specific expression analysis revealed prominent expression patterns of GhWOX4 and GhWOX14 in cotton internodes and roots, suggesting their involvement in vascular tissue development. Functional studies utilizing VIGS (virus-induced gene silencing) demonstrated that the knockdown of GhWOX4 and GhWOX14 resulted in a significant reduction in stem diameter and bast fiber production. This result suggests that secondary phloem fiber development is regulated by GhWOX4 and GhWOX14 genes in cotton. Additionally, the metabolic profiling of VIGS plants revealed significant alterations in amino acids, organic acids, and sugars, with implications for primary metabolic pathways. These findings suggest that GhWOX4 and GhWOX14 play pivotal roles in cotton plant development, including vascular tissue growth and phloem fiber production, and metabolic regulation.