Master of Science / Food Science Institute / Koushik Adhikari / The market of nail polish has been booming in recent years. Research on nail polish is scarce. A sensory lexicon for nail polish has been developed at Kansas State University, but how sensory factors affect female consumers’ acceptability of nail polish has not been examined. Also, other factors, such as price and usage characteristics that could affect consumers’ acceptability, are yet to be determined. A nail polish consumer study was conducted at Kansas State University to explore several sensory and non-sensory factors that could affect female consumers’ acceptability of nail polish. Eight nail polish samples, belonging to four categories, namely, regular (REG), gel (GEL), flake (FLK) and water-based (WAT), were evaluated by each of the 98 female consumers. The questionnaire consisted of three sections – application, observation and general usage questions. Results showed that consumers rated the samples similarly in both the application and observation sections. In general, consumers preferred the REG and the GEL samples more than the FLK and the WAT samples. Among all the sensory attributes, appearance attributes were the major attributes that affected consumers’ overall acceptability, while aroma had negligible impact on acceptability. Some sensory attributes like runny, shininess, opacity, spreadability, smoothness, coverage and wet-appearance were found to drive the consumer’s overall acceptability positively, while others such as pinhole, fatty-edges, blister, brushlines, pearl-like, flake-protrusion, glittery and initial-drag impacted their liking negatively. Four clusters of consumers were identified based on the consumers’ overall liking scores for both the application and observation sections. Considering all the factors that could affect consumers’ acceptability, sensory appeal, price, and conveniences of usage were the top factors picked by consumers. Age was also a factor that affected consumers’ acceptability for some of the samples. Consumers’ overall acceptability for these studied samples could guide a beauty store or a nail salon on building their selection on nail polishes. Consumers’ acceptability on different sensory attributes could help a nail polish company modify or improve their nail polish formula. The consumer cluster information could benefit a nail polish company on marketing a specific category of product and advertising to a specific group of consumers.

Les premiers véhicules autonomes ne seront capables de gérer la conduite que sur certaines portions de trajet. Le conducteur, qui pourra être engagé dans une tâche non relative à la conduite, doit être prévenu de reprendre la main avant la fin de disponibilité du mode autonome. L’objectif de cette thèse est de proposer et d’optimiser un signal vibratoire de rappel à la conduite qui soit détectable par tous, et jugé satisfaisant par les conducteurs, ou au moins acceptable étant donné sa signification et le contexte. Le contexte de roulage, la concentration du sujet sur une tâche non relative à la conduite et la diversité interindividuelle doivent être pris en compte. Un prototype de siège à retours vibratoires et un protocole de test en conditions de conduite autonome ont été mis au point, grâce à des expériences préliminaires. Les paramètres de construction d’un signal ont été formalisés et sélectionnés pour permettre la construction d’un plan d’expérience. Une évaluation quantitative de la détection et de la satisfaction pour les 16 signaux issus du plan d’expérience a été réalisée sur 80 sujets en conditions de conduite autonome. L’analyse par modélisation a permis d’identifier les paramètres du signal les plus influents sur les deux critères d’intérêt, et les valeurs de paramètres garantissant la meilleure satisfaction et une haute détection. Enfin, une étude en simulateur a permis de montrer l’intérêt de la modalité sensorielle tactile en complément de l’auditif lors du rappel à la conduite. / In the early steps of developments, autonomous vehicles carry out the driving only on determined road section. The driver, who may be focused in a non-related to driving task, must be warned before the end of the autonomous mode to take over the driving. This PhD work aims at offer and optimize a vibrotactile take-over notification (TON). This TON must be detected by any drivers and evaluated as satisfying, or at least acceptable considering its meaning and the context. The driving environment, the concentration of the subject in a non-related to driving task, as well as the diversity of the drivers have to be considered. A seat prototype and a protocol of evaluation in autonomous driving conditions were developed. The design parameters of a signal were established and selected to build a Design of Experiments (DoE). A quantitative evaluation of the detection and the satisfaction of the 16 signals from the DoE was performed based on 80 subjects in autonomous driving conditions. The influents parameters of the signals on the two evaluated criteria, and the settings optimizing the satisfaction and insuring a high detection level were identified by modelling. Finally, a simulator study showed the interest of tactile modality in addition to auditory modality during take-over request.