Search results

This paper treats the problem of scheduling seafaring staff inspired from a real case study, where the shipowner operates several vessel categories that require specific skills aiming to achieve a fair workload distribution and minimizing incompatibility between workers while meeting legal constraints, including requirements for days off and rest intervals between shifts.

A mixed integer linear problem (MILP) formulation has been built to address the seafaring staff scheduling problem by integrating multiple objectives and constraints. The model’s performance is tested through experimental results across varying parameter adjustments.

Our model was tested and validated using the XPRESS solver, and the results demonstrate its effectiveness in meeting the specified objectives and constraints. Notably, findings reveal that increasing the number of qualified workers leads to improved gains, until a certain threshold. Additionally, expanding the size of the workforce can result in longer execution times, specifically when incompatibility increases.

The originality of this study lies in proposing a generic novel model that deals with maritime staff scheduling, incorporating worker incompatibilities and workload fairness as key objectives.

In recent times, stretch denim garments have become very popular amongst consumers as the garment is able to provide body fit and body comfort at the same time. The purpose of this study is to investigate the effect of abrasion on the change in surface appearance, mass loss and ultimate tensile properties of the stretch denim fabric in different directions (warp, weft and biased).

After abrading the fabrics in three different directions (warp, weft and biased), the loss in ultimate tensile properties, mass loss and surface appearance has been investigated in the respective directions of abrasion (warp, weft and biased). The study also encompasses the effect of different types of stretch yarn with varying levels of elastane content on such unidirectional abrasive damage.

It is seen that with the same level of abrasion cycles, the fabric's response in terms of mass loss and loss in ultimate tensile properties are different in different directions. The mass loss due to abrasion in biased direction is found to be minimum. The loss in ultimate tensile properties due to abrasion was highest in the weft direction. It is also found that the higher mass loss due to abrasion does not always result in a greater loss in ultimate tensile properties. The composition and the structure of the weft yarn significantly affected the extent of the mass loss and the loss in ultimate tensile properties during abrasive damage.

The impact of abrasive damage in terms of mass loss and loss in tensile strength along the different directions of denim fabric has not been explored till date. Abrasion of fabric can be done both in multi-direction (Lissajous motion) as well as in uni-direction (linear motion). The multidirectional abrasion provides a holistic or comprehensive idea of the fabric's response to the abrasive damage but does not take into consideration the fabric's anisotropic response to the abrasive damage. Most of the earlier investigation related to abrasive damage of denim fabric has been done in instruments where the motion of the abrader is multidirectional (Lissajous) in nature. For greater depth of understanding about the fabric performance under abrasive damage along the various direction (warp, weft and biased), unidirectional abrasion is conducted in this study.

In recent times, the usage of elastane-containing denim garments has increased, as it provides fit and comfort both at the same time. The purpose of the study is to understand the effect of abrasion on the durability of comfort related to body movement and shape retention property of the stretch-denim fabric.

The paper investigates the effect of abrasion on the initial tensile properties, recovery and resilience properties of the stretch-denim fabric. Further, to analyse the effect of the composition of the elastane yarn, three different types of elastane yarns having different types of sheath (covering) fibre, structure and different levels of elastane content have been used in the weft.

The comfort related to body movement and the shape retention properties of the stretch-denim fabric got affected due to abrasive damage. The elastane yarn composition and structure played an important role in determining the extent of the change in such properties during abrasion. The fabric with a higher level of elastane content suffered a greater loss in shape-retention properties due to abrasion. The extent of mass loss in stretch-denim fabric does not always correlate to the extent of loss in the comfort and shape-retention properties.

Most of the earlier studies have investigated the effect of abrasion on the durability aspect of the stretch-denim fabric. In a practical scenario, the stretch-denim garments are rarely discarded due to tearing or change in appearance but mainly due to bagging, i.e. distortion in shape after usage. Thus, the study on the combined effect of the abrasion and cyclic loading on the comfort and shape-retention properties will help to predict the performance of the apparel during usage.

The main factors affecting consumers when selecting denim garments are aesthetic, appearance and fashion. Besides these factors, comfort and performance properties of the denim garments during usage are very important. The purpose of this paper is to determine the effects of different finishing processes on the performance properties of 100 percent cotton and 98 percent cotton+2 percent elastane denim fabrics.

The research design for this study consists of experimental study. In order to evaluate the effects of finishing on the performance properties of fabrics, eight types of fabrics were selected for evaluation. Rigid, resin, bleaching and softening type fabrics with and without elastane were analyzed statistically.

The results obtained in the study clearly showed that the types of finishing and elastane fiber in the fabric structure had a significant influence on mechanical and comfort properties of denim fabrics.

As a result of the literature review, it was seen that there were limited studies concerning mechanical, functional and comfort properties of denim fabrics together. In this study, the effects of finishing processes on the tear strength, stiffness, drape, mechanical and thermal comfort characteristics were deeply evaluated.

The liquid water and water vapour transfer properties of fabrics play an important and decisive role in determining thermal comfort properties of clothing systems. The purpose of this paper is to analyse the effects of fabric composition (98 percent cotton–2 percent elastane and 100 percent cotton) and finishing treatments (rigid, resin, bleaching and softening) on the wicking, drying and water vapour permeability (WVP) properties of denim fabrics.

The research design for this study consists of experimental study. Two fabric compositions (98 percent cotton–2 percent elastane and 100 percent cotton) and four finishing treatments (rigid, resin, bleaching and softening) were evaluated to see the effects of elastane and finishing treatments on wicking, drying and WVP properties of woven denim fabrics. Results were analysed statistically.

Experimental results showed that the transfer wicking, drying and WVP values of denim fabrics were significantly influenced by fabric weight, fibre composition and finishing treatments.

The wicking ability of sweat from the skin to the outer environment of a skin contact fabric layer is the primary requirement.

As a result of the literature review, it was seen that there are some studies in the literature about comfort properties of denim fabrics, but there is no study concerning the water vapour transmission, wicking and drying properties of denim fabrics.

In this paper, nanocomposites are synthesised with Tunisian natural clay which has the advantage of being inexpensive. In fact, it is simply a mixture of several sorts of clays (kaolinite, dolomite, calcite, illite, and quartz). This clay has been cleaned, purified, dried, and steered with polyacrylate resin which is actually used in the textile field for several types of other applications, such as comfort, elasticity or impermeability. The samples have been examined by x-ray diffraction (XRD) and scanning electron microscopy (SEM) in order to observe their compositions and ensure the formation of the nanocomposites .The mixture resin/clay is deposited onto 100% cotton fabric and tested by using a PASOD device that measures the necessary voltage to maintain the temperature difference between the inside and the outside of the fabric which is equal to 20°C. The enhancement of the fabric thermal insulation is noticed by calculating the difference in temperature between the inside and the outside of the fabric. The coating which is a nanocomposite PAC/clay has been modelled which proves that it is a Hamiltonian model as the clay percentages are superior to 4% when the clay dispersion and the free-volume are calculated.

The purpose of this paper is to model the relationship between manufacturing parameters, especially finishing treatments and instrumental tactile properties measured by Kawabata evaluation system.

Two soft computing approaches, namely artificial neural network (ANN) and fuzzy inference system (FIS), have been applied to predict the compression and surface properties of knitted fabrics from finishing process. The prediction accuracy of these models was evaluated using both the root mean square error and mean relative percent error.

The results revealed the model's ability to predict instrumental tactile parameters based on the finishing treatments. The comparison of the prediction performances of both techniques showed that fuzzy models are slightly more powerful than neural models.

This study provides contribution in industrial products engineering, with minimal number of experiments and short cycles of product design. In fact, models based on intelligent techniques, namely FIS and ANNs, were developed for predicting instrumental tactile characteristics in reference to finishing treatments.

The purpose of this paper is to study the influence of friction phenomenon generated by a disc brake on the dynamic behaviour of a one-stage spur gear.

A theoretical model is proposed and is based on both theories of Coulomb and Dahl in order to analyse the influence of disc brake friction phenomenon on the dynamic behaviour of one-stage spur gear transmission.

The influence of brake friction on the dynamic behaviour of the transmission is investigated using the proposed model and leads to observe higher vibration levels when the braking is occurring as well as the emergence of significant efforts at the gear teeth.

A new numerical model based on the implicit numerical integration technique of Newmark coupled with Newton-Raphson method is proposed to study the influence of friction phenomenon of a disc brake on the dynamic behaviour of one-stage spur gear.

This study aims to the OQuaRE quality model to the developed methodology.

Ontologies are formal, well-defined and flexible representations of knowledge related to a specific domain. They provide the base to develop efficient and interoperable solutions. Hence, a proliferation of ontologies in many domains is unleashed. Then, it is necessary to define how to compare such ontologies to decide which one is the most suitable for the specific needs of users/developers. As the emerging development of ontologies, several studies have proposed criteria to evaluate them.

In a previous study, the authors propose a methodological process to qualitatively and quantitatively compare ontologies at Lexical, Structural and Domain Knowledge levels, considering correctness and quality perspectives. As the evaluation methods of the proposal are based on a golden-standard, it can be customized to compare ontologies in any domain.

To show the suitability of the proposal, the authors apply the methodological approach to conduct comparative studies of ontologies in two different domains, one in the robotic area, in particular for the simultaneous localization and mapping (SLAM) problem; and the other one, in the cultural heritage domain. With these cases of study, the authors demonstrate that with this methodological comparative process, we are able to identify the strengths and weaknesses of ontologies, as well as the gaps still needed to fill in the target domains.

Using these metrics and the quality model from OQuaRE, the authors are incorporating a standard of software engineering at the quality validation into the Semantic Web.

Total productive maintenance consists of strategies and procedures that aim to guarantee the entire functioning of machines in a production process so that production is not interrupted and no loss of quality in the final product occurs. Planned maintenance is one of the eight pillars of total productive maintenance, a set of tools considered essential to ensure equipment reliability and availability, reduce unplanned stoppage and increase productivity. This study aims to analyze the influence of statistical reliability on the performance of such a pillar.

In this study, we utilized a multi-method approach to rigorously examine the impact of statistical reliability on the planned maintenance pillar within total productive maintenance. Our methodology combined a detailed statistical analysis of maintenance data with advanced reliability modeling, specifically employing Weibull distribution to analyze failure patterns. Additionally, we integrated qualitative insights gathered through semi-structured interviews with the maintenance team, enhancing the depth of our analysis. The case study, conducted in a fertilizer granulation plant, focused on a critical failure in the granulator pillow block bearing, providing a comprehensive perspective on the practical application of statistical reliability within total productive maintenance; and not presupposing statistical reliability is the solution over more effective methods for the case.

Our findings reveal that the integration of statistical reliability within the planned maintenance pillar significantly enhances predictive maintenance capabilities, leading to more accurate forecasts of equipment failure modes. The Weibull analysis of the granulator pillow block bearing indicated a mean time between failures of 191.3 days, providing support for optimizing maintenance schedules. Moreover, the qualitative insights from the maintenance team highlighted the operational benefits of our approach, such as improved resource allocation and the need for specialized training. These results demonstrate the practical impact of statistical reliability in preventing unplanned downtimes and informing strategic decisions in maintenance planning, thereby emphasizing the importance of your work in the field.

In terms of the originality and practicality of this study, we emphasize the significant findings that underscore the positive influence of using statistical reliability in conjunction with the planned maintenance pillar. This approach can be instrumental in designing and enhancing component preventive maintenance plans. Furthermore, it can effectively manage equipment failure modes and monitor their useful life, providing valuable insights for professionals in total productive maintenance.