Approximately 80% of the population will experience low-back pain within their lifetime. Significant research efforts have focused on compressive loading as an injury mechanism that could lead to low-back pain and injury. However, the influence of shear loading, and its relationship to vertebral tissue tolerances as well as modulating factors for these tolerances have not been studied as extensively. The primary objective of this thesis was to produce a series of investigations that begin to determine the roles of different modulating factors such as posture, compression, bone density, bone morphology, and repetitive load magnitude on measured vertebral joint shear failure tolerances. The thesis comprises four independent studies using in vitro mechanical testing, imaging modalities, and finite element modeling. Each of the in vitro studies within this thesis used a validated porcine cervical model as a surrogate for the human lumbar spine. The first study employed in vitro mechanical testing to investigate the combined roles of flexion/extension postural deviation and compressive load on the measured ultimate shear failure tolerances. Peripheral quantitative computed tomography scans of the pars interarticularis and measurements of vertebral bone morphology were used in the second investigation along with in vitro mechanical testing to identify the morphological characteristics that can be used to predict ultimate shear failure tolerances. The influence of sub-maximal shear load magnitude on the cumulative shear load and number of loading cycles sustained prior to failure were investigated with in vitro mechanical testing in the third study. Finally, a finite element model of the porcine C3-C4 functional spinal unit was used to investigate the plausibility of hypotheses, developed from previous research and the findings of the first investigation for this thesis, surrounding alterations in measured ultimate shear failure tolerances as a function of changes in facet interaction. Results from the first investigation showed that there was no statistically significant interaction between postural deviation and compressive force on ultimate shear failure tolerance. However, ultimate shear failure tolerance was reduced (compared to neutral) by 13.2% with flexed postures, and increased (compared to neutral) by 12.8% with extended postures. Each 15% increment (up to a maximum of 60% of predicted compressive failure tolerance) in compressive force was met with an average 11.1% increase in ultimate shear failure tolerance. It was hypothesized that alterations in flexion/extension posture and/or compressive force altered the location for the force centroid of facet contact. These changes in the location of facet contact were hypothesized to produce subsequent changes in the bending moment at the pars interarticularis that altered the measured ultimate shear failure tolerance. The three leading factors for calculating of measured ultimate shear failure tolerance were the pars interarticularis length for the cranial vertebra, the average facet angle measured in the transverse plane, and cortical bone area through the pars interarticularis. A bi-variate linear regression model that used the cranial vertebra’s pars interarticularis length and average facet angle as inputs was developed to nondestructively calculate ultimate shear failure tolerances of the porcine cervical spine. Longer pars interarticularis lengths and facets oriented closer to the sagittal plane were associated with higher measured ultimate shear failure tolerances. Fractures observed in this investigation were similar to those reported for studies performed with human specimens and also similar to reported spondylolitic fractures associated with shear loading in humans. This provided additional evidence that the porcine cervical spine is a suitable surrogate in vitro model for studying human lumbar spine mechanics. Altered sub-maximal shear load magnitude create a non-linear decrease in both the number of cycles and the cumulative shear load sustained prior to failure. These findings suggested that estimates of cumulative shear load should assign greater importance to higher instantaneous shear loads. This was due to an increased injury potential at higher instantaneous shear loads. Cumulative load sustained prior to failure was used to develop a tissue-based weighting factor equation that would apply nonlinearly increased weight to higher shear load magnitudes in estimates of cumulative shear load. A finite element model of the porcine C3-C4 functional spinal unit was created, and simulations were performed using similar boundary conditions as the comparable in vitro tests, to assess the plausibility of the moment arm hypothesis offered within the first investigation of this thesis. Moment arm length between the force centroid of facet contact and the location of peak stress within the pars interarticularis was increased for flexed postures and decreased for extended postures. Alterations in moment arm length were larger for postural deviation than compressive force, suggesting a secondary mechanism to explain the observed increase in shear failure tolerance with higher compressive loads from the first investigation. One such possibility was the increase in the number of contacting nodes with higher compressive forces. Alterations in moment arm length were able to explain 50% of the variance in measured ultimate shear failure tolerances from the first study. Thus, the finite element model was successful in demonstrating the plausibility of moment arm length between the force centroid of facet contact and the pars interarticularis as a modulator of measured ultimate shear failure tolerance. This thesis has developed the basis for understanding how failure of the vertebral joint exposed to shear loading can be modulated. In particular, this thesis has developed novel equations to predict the ultimate shear failure tolerance measured during in vitro testing, and to determine appropriate weighting factors for sub-maximal shear forces in calculations of cumulative shear load. Evidence presented within this thesis also provides support for the long-standing moment arm hypothesis for modulation of shear injury potential.

Current trends in industry are leaning towards specialized production systems and sedentary computer work tasks that are associated with low and less varying mechanical exposures. It has been suggested that physical variation is an effective intervention to reduce local fatigue and potentially musculoskeletal disorders. However, little is known in how the differences between physical variation patterns affect physiological and psychophysical responses. The general purpose of this thesis was to explore the biophysical effects of varying force amplitudes using forces, cycle times, and duty cycles that are relevant to occupation and longer-term health outcomes. Fifteen healthy males performed an elbow extensor sustained isometric exertion at 15% Maximum Voluntary Force (MVF), an intermittent contraction between 0% MVF and 30% MVF (On/Off), an intermittent contraction between 7.5% MVF and 22.5% MVF (MinMax), an intermittent contraction between 1% MVF and 29% MVF (1 Percent), and a sinusoidal contraction between 0% and 30% MVF (Sinusoidal). Eight commonly used measurement tools recorded biophysical responses as participants performed each condition for up to 60 minutes or until exhaustion, during 60 minutes recovery, and at 24 hours post-exercise. Measures included electromyography of the triceps muscles, mechanomyography, blood flow, heart rate, stimulated tetani and twitch responses, maximum exertions, and perceived exertion. The rate of response during exercise and comparisons between baseline, cessation, and recovery values were used to assess fatigue responses. This research shows that implementing physical variation, at the same mean amplitude, may provide reduced fatigue rate and that the magnitude and shape of the intermittent force variations affect exercise and recovery measures. Time varying forces may therefore provide the necessary mechanism to encourage beneficial physiological responses that would improve long-term health and well being of workers at low-load jobs.

The lifting associated with childcare has been linked to musculoskeletal disorders (MSDs) in mothers (Griffin & Price, 2000; Sanders & Morse, 2005). The purpose of the current study was to investigate, for the first time through observation, the lifting of young children by mothers in the home environment to identify risk factors which might give rise to MSDs. Twenty five mothers with one or two children weighing between 9 and 15kg (n = 30) completed a self-report survey modified for the New Zealand context (The Ergonomics of Caring for Children (Sanders & Morse, 2005)). They also took part in a structured observation of lifting in the home using a checklist based on the New Zealand Manual Handling Hazard Control Record NZMHHCR (OSH & ACC, 2001). Modifications were derived from careful consultation of current literature to enable contributory factors related to the load, the mother, the environment and the task to be assessed and a rating of low, medium, or high risk to be assigned to each factor. A protocol to guide risk assessment was developed to accompany the tool. The modified observational checklist was named the OMLITH (Observing Mothers Lifting In The Home). Survey data identified the mothers as aged between 28 and 40 years, predominantly NZ European, and of average height (χ = 1.69cm) and weight (Body Mass Index = 24). The children in the sample weighed between 9 and 14.5kg and had an average age of 17months. All the mothers were either married (n=20) or living with a significant other (n=5) and their partners frequently (n=13) or always (n=12) helped with childcare. The mean time mothers spent per week on the following activities were: sleep, 6.8hrs (n=25), housework, 14.9hrs (n=25), exercise, 2.9hrs (n=22), watching television or using the home computer, 4.3hrs (n=22), hobbies, 2.2hrs (n=19), gardening or home maintenance, 2.9hrs (n=18). Thirteen of the mothers worked (3 full-time, 10 part-time) and 20 mothers used childcare services. Ratings of the physical stress associated with 50 childcare tasks showed that mothers differentiated between tasks in terms of physical stress to a significant degree (p.000), typically rating ‘Bending while carrying a child’ as almost twice as stressful as the average rating. Other categories rated significantly above the average stress rating were: ‘Use of a backpack to carry infant/child’, ‘Use of baby jogger’, ‘Carrying child on your shoulders’, ‘Standing bent over to wash child in bath or sink’, ‘Lifting child into or out of cot’, ‘Prolonged squatting or stooping while playing with child’, and ‘Placing child in car seat or removing child from car seat’. Mothers reported experiencing MSDs most commonly in the low back (n=16), and the neck, shoulder and upper back (n=8 each). Data from the 87 observations using the OMLITH showed that children were a challenging load due to their moving centre of gravity, and were often unpredictable or awkward to handle. The grip required to lift a child more often than not fell outside the National Institute for Occupational Safety and Health (NIOSH) recommendation. In 72.9% of tasks the child’s weight created a high risk level. The lifting tasks involved horizontal and vertical lift distances that presented a moderate to high risk level in 82.8% of situations. Lifting while twisting and side-bending was assigned a moderate to high risk level in 72.4% of tasks. Risk associated with working at an externally controlled pace; and handling children while seated or kneeling/crouching was also observed. The home environment presented risk associated with obstacles, a variety of floor surfaces and stairs or slopes. Mothers were also observed lifting in confined spaces. Individual factors identified as important considerations were: a mismatch between mothers’ strength and fitness and the lifting requirements, pain or injury, pregnancy, and fatigue. The structured checklist proved to be an appropriate tool to identify the contributory risk factors present when mothers lift in the home and to make an assessment of the level of risk. Results suggest a notable number of risk factors which might give rise to MSDs are present when mothers lift their children at home. The author concludes that further research is warranted to quantify risks, to identify prevention strategies for MSDs in this population, and to guide health providers with regard to treatment and rehabilitation of mothers with MSDs.

Globally, there is an increasing tendency for occupational legislation and practice to require that employers actively involve their employees in the process of identifying, assessing and addressing the risk of injury in the workplace. Despite this, there is a paucity of research evaluating the effectiveness of participatory ergonomics in reducing occupational injury outcomes. In particular, a review of the literature fails to identify research that reports a change in the risk of injury at the level of the individual worker. The objectives of this study were to determine whether a participatory ergonomics approach to the control of workplace hazards and manual hazards in particular, could reduce the occurrence and severity of injury among a working population at risk.The research design was that of a longitudinal pre-post intervention study, with one intervention and three comparison groups. The observational period between 1 July 1988 and the 31 October 1995, comprised a 4.3 year pre-intervention period and a 3- year post-intervention period. The Intervention Group was a population of hospital cleaners at a high risk of injury. Three comparison groups were used, namely orderlies from the same hospital, cleaners from a similar hospital, and all the cleaners in the State of Western Australia. The primary outcome measure of occurrence was that of a lost- time injury (LTI).To obtain parameters of injury severity, each LTI was measured in terms of the associated CP1-adjusted workers' compensation claim cost and the number of hours lost from work (duration). The data were obtained three years after the observational period, to improve the likelihood that the claims had been finalised. Aggregate level LTI data were obtained for all four groups. Individual-level data were also obtained for the Intervention Group and the Orderly Services Group, whether injured or not. These ++ / data included the age, gender, hours worked and work experience of the subjects. Also, where there was an LTI, it was determined whether or not the mechanism of injury was from manual handling. Using these data, two analytical approaches were then undertaken. Study 1 assessed the aggregate-level LTI data of the four groups. Study 2 evaluated individual-level data for the Intervention Group and the Orderly Services Group.The results demonstrate statistically significant post-intervention reductions In all measures of LTI occurrence for the Intervention Group. In particular, after allowance for age, gender and work experience, there was a two thirds reduction in the rate of LTI per hour worked. No reduction in injury occurrence was observed for any of the comparison groups. The severity of each injury, as measured by claim cost and duration, did not change after the intervention for the Intervention Group.This study indicates that a small group of unskilled workers, with the facilitation of an ergonomist, can successfully undertake an iterative process of identifying and assessing hazards and make recommendations for their control. In doing so, even where the primary focus is on manual handling hazards, a reduction in the risk of injury from both manual handling and non-manual handling mechanisms can be achieved. Participatory ergonomics, by investing hazard management skills within employees, increases the likelihood that solutions to problems will be accepted, and should release ergonomists to consult to a greater number of workplaces than if they work independently of employee participation. The evaluation of interventions in a variety of workplace settings is recommended, to confirm participatory ergonomics as an effective tool for the reduction of the global burden of occupational injury.

<p>Ombordanställda i svenska rederier har under många år legat högre i olycksstatistiken än anställda i land. Detta problemförhållande bygger vårt examensarbete till stor del på.</p><p>Detta examensarbete syftar till att undersöka hur de svenska rederierna arbetar för att förhindra arbetsrelaterade olyckor ombord.</p><p>Arbetet har utförts med metodtriangulering. Vi har intervjuat fyra svenska rederier angående deras arbete med arbetsrelaterade olyckor. Utifrån de svar vi inhämtat från rederierna så utformade vi en enkät som 10st ombordanställda fick svara på.</p><p>Resultatet av vårt arbete visade att rederierna känner till problemet och att deras förebyggande arbete till stor del bygger på att öka inrapporteringen av olyckor och tillbud från fartygen. Främst med nya inrapporteringsprogram som skall förenkla inrapporteringsproceduren. Från de enkätsvar vi fick så kunde vi se att det finns ett stort mörkertal i inrapporteringen av olyckor ombord.</p> / <p>Employees on Swedish shipping companies have for several years topped the accident statistics when compared with land based jobs.</p><p>The purpose of this study is to examine how the Swedish shipping companies are working to prevent work related accidents.</p><p>The study was made through interviews with four Swedish shipping companies.</p><p>And a questionnaire answered by 10 onboard employees from Swedish shipping companies.</p><p>The result of our study shows that the companies are working with preventing accidents onboard mainly through different measures to increase the reporting frequency from the ships to the office. In the answers we received from the questionnaires we could see that the reporting frequency on board is poor.</p>

This report describes a solution to an adjustment problem found on “The Armadillo”. This product can be described as a bicycle, but with four wheels instead of two, and has a somewhat more complex construction than an electric bicycle. In today’s construction there are difficulties in using the bike if the driver is not within the range of 170-190 cm tall, which obviously limits the user of the product. The main user are those who work with the product. The task of the project was therefore to find a solution to this problem, with free hands without major limitations. This has been done in cooperation the company that owns the product, Velove, where a couple of visits have been made to study the design further, as well as examine the possibilities and limitations that exist. Methods such as Fredy Olsson with small modification have been used, this has simplified the work as a clear structure has been obtained on approaches. The project group has used different ideas to generating and evaluating product ideas, including where we included other students for inspiration, in order to reach a promising concept within the group. Two ready-made digital prototype concepts have been developed in Catia V5, where one of them has advanced into a physical prototype in plastic material. The construction allows a longer span and allows more drivers to use today’s Armadillo. The solution is another smaller rail that goes over the today’s existing rail witch makes it possible to further adjust the length span for the driver. The construction is a superstructure on the existing Armadillo and does not require a reconstruction of the bike.

Detta examensarbete har utförts i samarbete med högskolan i Skövde med syftet att genom simulering och optimering påvisa produktionstekniska parametrars påverkan på ett systems prestanda. Examensarbetets mål var att från data ta fram en simuleringsmodell som på ett korrekt sätt avspeglade verkligheten och som kunde användas vid optimering.  En metod för modellbygge togs fram genom en kombination av teorier från Banks (1998) och Lundgren et al. (2010), som sedan praktiserades genom att bygga en modell på data från en verklig produktionsanläggning. Frågeställningen och kraven som utarbetats tillsammans med uppdragsgivaren gällande modellens prestanda utvärderades innan optimeringsparametrar för sekvens, batch-storlekar samt Buffer- och Store-kapacitet definierades och stiftades. Det resultat som optimeringen genererade analyserades, utvärderades och jämfördes med resultat från egna experiment för att säkerställa dess trovärdighet.  Projektet har bidragit med en ny syn på det produktionsflöde som simulerats och visat att det inte alltid är de uppenbara parametrarna som påverkar processen mest. Resultatet visar på förbättring av total kapacitet med 64%, samt en ledtid som kortades ner med över 24 timmar. Arbetet belyser fördelarna för ett företag att använda sig av simulering i sitt arbete med produktionsutveckling, för att minimera risken att lägga resurser på förbättringar med lägre förbättringspotential än andra.  Den simuleringsmodell som tagits fram och den djupare förståelsen för densamma, kommer ligga till grund för fortsatt arbete med att undersöka produktionstekniska parametrar och hur det korrelerar med varandra. / This thesis project has been carried out in collaboration with Skövde University with the purpose of demonstrating, through simulation and optimization, production parameters impact on a system’s overall performance. The aim of the thesis was to create a simulation model from production data that accurately reflect a real-life system and could be used for optimization.  A method of simulation model construction was developed through a combination of theories from Banks (1998) and Lundgren et al. (2010), which were practiced by building a model based on data from a real production facility. The research questions and requirements were developed with the client regarding the performance of the model and were evaluated before optimization parameters for sequence, batch-size and Buffer- and Store capacity were defined and established. The result that the optimization generated was analyzed, evaluated, and compared to results from own experiments to ensure its credibility.  The project has contributed to a new view of the production flow that was simulated and showed that the most obvious parameters are not always the ones that affect the process the most. The results show an improvement of 64% in total capacity and over 24 hours shorter lead time. The report highlights a company’s benefits with using simulation in its work with production development. Especially to minimize the risk of wasting resources to improvements with lower potential than others.  The simulation model developed in the project will serve as basis for further work in understanding and investigating productions technical parameters and their correlations with each other.

Este trabalho propõe diretrizes para a avaliação dos impactos da produção enxuta (PE) sobre as condições de trabalho de operadores de chão-de-fábrica, com ênfase no contexto da indústria da manufatura. As diretrizes foram aplicadas em um estudo de caso em uma linha de montagem de colheitadeiras de um fabricante de máquinas agrícolas que vem implementando, desde 2001, a PE como estratégia de produção em nível corporativo. Inicialmente, foi avaliado, qualitativamente, o nível de implementação das práticas enxutas (NIPE) na linha estudada. O instrumento de avaliação utilizado foi uma lista de verificação com 11 práticas de PE, subdivididas em 92 itens. A lista foi preenchida após a realização de 15 entrevistas com gerentes e supervisores de diversas áreas da empresa, observações diretas, análise de alguns padrões de trabalho e relato dos operadores. Em seguida, foram realizadas as seguintes atividades de campo para avaliar os impactos humanos da PE: a) entrevistas semi-estruturadas com seis técnicos e um engenheiro de segurança; b) coleta de dados de produção e segurança e saúde no trabalho; c) entrevistas semi-estruturadas com três grupos de dez operadores para análise da percepção destes sobre os aspectos positivos e negativos da PE, além de conduzir discussões de questões específicas desse sistema; d) aplicação de dois tipos de questionários, um para avaliar as condições atuais de trabalho (com 56 questões) e outro para avaliar as diferenças entre os sistemas antigo e novo de produção (com 42 questões), respondidos por 91 e 67 operadores, respectivamente, de um total de 122; e) retorno dos resultados dos questionários para um grupo de 65 operadores para validação da análise desses resultados. Os resultados das diversas etapas foram analisados e discutidos segundo uma estrutura de análise de dados por similaridade de assunto, denominadas de constructos. A avaliação da PE foi compilada no constructo NIPE e os impactos desta sobre as condições de trabalho foram organizados nos constructos de organização do trabalho, conteúdo do trabalho, melhoria contínua e segurança e saúde no trabalho. De forma geral, o estudo indicou que os operadores percebem de forma positiva suas condições de trabalho e que elas melhoraram em função da adoção das práticas de PE. / This study presents guidelines to evaluate the impacts of lean production (LP) on working conditions of front-line workers, emphasizing the context of manufacturing industry. The guidelines were tested in a case study carried out in the assembly line of a heavy machinery agricultural manufacturer. Since 2001 this manufacturer has been adopting LP as its manufacturing strategy at corporate level. As the first step of this study, the extent to which LP practices were adopted in the assembly line was assessed. The main assessment tool was a check-list that had 11 LP practices divided into 92 items. The check-list was filled out based on 15 interviews with managers and supervisors, direct observations, workers´ informal reports and the analysis of some work standards. Then, five activities were undertaken to assess the human impacts of LP: a) interviews with six safety specialists and one safety engineer; b) data collection on both health and safety and production performance; c) interviews with three groups formed by ten workers in order to detect their perceptions on both negative and positive impacts of LP – questions on the impacts of specific lean tools were also made; d) application of two types of questionnaires – one of them had the objective of evaluating perceptions on current working conditions (56 questions), the other aimed to evaluate perceptions on differences between the old and the current production system (42 questions); e) a feedback meeting to discuss with workers the results of the questionnaires. The results of all data collected were organized in five groups: level of implementation of LP practices; work organization, work content, continuous improvement and health and safety. Overall, the results pointed out that workers had a positive perception on their working environment and that working conditions have improved since LP was adopted.

Services are making a huge impact in the business sector especially in the developed countries. As services are customer-centric, there is a need for an enhanced process framework connected to integrated service development. Such a framework should ideally address value propositions meeting specific customer needs in identifying corresponding service offerings. In this context, this thesis aims to explore on how value propositions are defined, developed, and communicated during the introduction of service offerings and to identify the ways to improve the process of value propositions. The work is carried out in the context of a major (Swedish) manufacturing company within a specific product context, namely, the telematics system. The main data collection methods are personal observations, semi-structured interviews, meetings, and company documents. The study seeks to answer three questions: First, what are the value propositions addressed by the current service offerings in telematics system in the context of heavy-duty vehicle equipment? Second, how value propositions are created during the development of these services offerings? Third, how can the service offerings for telematics system be improved through the process of value proposition? The study found that two types of value propositions namely customer value proposition and stakeholder value proposition are addressed by the service offerings in telematics system. Additionally, it is found that value propositions are created in relation to service offerings. Finally, the thesis proposes a six-step conceptual framework to create better value propositions during the development of service offerings. The presented framework is applied to the current value proposition process at the case company and improvement suggestions are proposed, which can impact the service offerings in the near future. The thesis has contributions to enhance or create new service offerings through addressing the value propositions and applying them. The results are beneficial for managers and developers who work in developing the future state scenarios or business models.

Failure of a parked unattended vehicle to remain stationary, otherwise known as vehicle rollaway, can result in property damage, injury or even fatality. Although the incidence of vehicle rollaway may be under reported, around 8% of drivers and 13% of Approved Driving Instructors surveyed indicated they had experienced a vehicle rollaway event. Unlike previous studies which focused only on the mechanical factors that may contribute to this phenomenon, the research presented in this thesis employed a more comprehensive, systems approach to explore additional factors related to the driver s interaction with the parking brake system at various interface levels. A mixed methods strategy collated data through two online surveys and three observational studies to explore the organisational, mechanical and driver related factors identified in a fault tree framework. The results indicated that current driver practice and interaction with the parking brake system may be contrary to legislative requirements and manufacturer s instruction. The findings suggested that a past experience of vehicle rollaway or parking brake system failure, had a statistically significant influence on whether the driver complied with the recommended practice. Driver interaction and the holding capability of the parking brake system were observed in 53 vehicles parked on three test gradients. The observations indicated that drivers were able to apply sufficient force to the parking brake lever to hold the vehicle stationary and that an additional degree of confidence in the system was provided by parking in gear. But, after driving a short commuting route, when the vehicle was parked with the parking brake lever applied to the lowest position to hold the vehicle and a gear was not selected, 63% of vehicles fitted with disc brakes rolled as the temperature returned to ambient. Discussion relates to the organisational, driver related and mechanical components of the parking brake system and in reference to Reason s Swiss Cheese model, considers how latent failures within the defensive layers of the system can contribute to rollaway. The research findings contributed to a change in UK driving standards and since 2015, drivers are recommended to park in gear at all times to reduce the risk of rollaway. This recommendation is likely to require a change in practice for up to 80% of Approved Driving Instructors who would not normally instruct new drivers in this way. Although this research focused on the manually operated parking brake system, the studies have uncovered results that can contribute to knowledge and are applicable to interaction with electronic parking brake systems. As parking brake systems develop, the Human Factors systems approach can be applied retrospectively and proactively to explore that interaction and prevent passenger vehicle rollaway.