The Review of Mark Planning Problem

Mark planning is one of the most important planning processes in garment industry. The major function is to generate a set of markers which is used as cutting guidelines or cutting templates in a cutting process. In other words, this process can be seen as a planning step of a cutting process which determines what sequence and how many parts will be cut. For the academic point of view, mark planning has been of interests for more than 15 years. Many papers were published with various objective functions, problem scenarios, and constraints. Therefore, a summarization of these papers representing key contents of each paper will be useful for researchers who are interested in this type of problem. The purpose of this paper is to introduce an exhaustive review of mark planning papers which is composed of three sections: the relevant background, the summary of papers, and the relationship between objective functions which is cost combinations and major garment characteristics. In conclusion, future researches should go forward the trend of integration between this process and other relevant processes in the production chain, e.g. cut scheduling, assembly planning, marker making

Demystifying process-level scalability challenges in fashion remanufacturing: An interdependence perspective

Abstract The purpose of this paper is to determine how process-level challenges can be solved in order improve scalability of fashion remanufacturing. In order to do so, and prescribe solutions, the paper first conducts a systematic literature review to reveal three categories of process-level challenges that are related to sourcing of input material, process throughput time, and skillset requirement. These categories further guided us in conducting case study with a Swedish charity-owned fashion remanufacturer for exploring how the challenges are addressed and solved in order to achieve process-level scalability. First, our study reveals a systematized approach to determine product-process categories defined by production volume and degree of remanufacturing. Second, by exploring the process-level challenges of six different remanufactured product groups in the case study organization we identify process-level requirements for scalability, and challenges when these are unmet. The findings show that in fashion remanufacturing (particularly disassembly and reassembly), low degree of coupling, high level of formalization of activities and low skill specificity can be ways to attain process-level scalability. Overall, this highlights the need to build lower interdependence between disassembly and reassembly during fashion remanufacturing

A study on crate sizing, inventory and packing problem

Ph.DDOCTOR OF PHILOSOPH

Seamless knitted sports bra design: A responsive system design exploration

ABSTRACT The transition of sports bras’ uses, from an active lifestyle to resting activities, requires dynamic and adaptable comfort properties of the design, as well as adequate breast support, fit, and comfort. Thus, the two-fold purpose of this study was to: (a) analyze the use of current materials and processes in the product development process of seamless sports bras, via industry interview and observation, and (b) propose a design solution for a seamless sports bra that offers variable breast support during running versus resting activities. Using a case study approach, an in-depth interview with a Santoni seamless knitting technician provided data that led to mapping out the design and product development processes used for prototyping seamless sports bras. A seamless business model for a sports bra was created, and relationships among the over-arching themes of planning, marketing, product development, innovation, and production, which emerged from the grounded theory analysis, were discussed. Moreover, a detailed Product Development framework and a Tech Pack model were created and used to communicate the new design for a responsive seamless sports bra. Interactions between design, prototyping and functionality and how these themes relate to the components of the tech pack were discussed. At the materials level, a biomimetic system framework was used to identify solutions to responsive interactions within wool/Nylon/spandex blended yarns and various knitting structures when actuated by moisture. Twenty pattern designs were knitted on a Santoni circular knitting machine, using two different yarn combinations: (a) wool/spandex, and (b) wool/nylon/ spandex. Physical properties of the knit swatches were documented, as well as their thickness when dry versus three different moisture activation situations: (a) immediately after wetting, (b) after 30 minutes of air-drying, and (c) after 60 minutes of air-drying. Results showed that the Santoni circular knitting technology has capabilities to create a variety of texturally knit fabric designs that have a wide range of thicknesses, densities, and moisture responsiveness properties. Selections of knit patterns were made based on the textile testing results and used to design a responsive sports bra that incorporated female sweat maps and sports bra user needs. Sustainability considerations regarding the wet processing of the new responsive design were implemented, and the bra samples were not dyed, but only cold-washed and tumble-dried at low temperature. Fifteen prototypes were developed via a Santoni circular seamless knitting machines and tested using human subjects and 3D body scanning technology. A convenience sample of fifteen semi-athlete female college students wore the new sports bra prototypes during three different moisture conditions: (a) before a run (dry), (b) after 30 minutes run on a treadmill (wet), and (c) after resting 30 minutes (starting to dry out). 3D body scans were collected in fully inhaled, as well as relaxed respiratory states after each condition. Questionnaires were used to evaluate comfort and responsiveness of the new design. The results revealed that the new responsive sports bra offers compression during the dry conditions, breathability and some level of breast support during running, and moisture management during the resting stage, all while offering high overall comfort and fabric softness. However, the length of the bra straps needs to be shortened, and the breast support during running needs improvement, therefore further design iterations are needed. The proposed integrative approach to the sports bra design offers a new framing for the systematic design process of a sports bra as a functional design garment and fills knowledge gaps within the seamless knitting process using performance wool blend yarns. The new biomimetic-inspired sports bra solution has a potential for commercial applications that can offer women a responsive, adaptable sports bra, to encourage healthier lifestyles, as well as to accommodate for the athleisure trend

Decision models for fast-fashion supply and stocking problems in internet fulfillment warehouses

Internet technology is being widely used to transform all aspects of the modern supply chain. Specifically, accelerated product flows and wide spread information sharing across the supply chain have generated new sets of decision problems. This research addresses two such problems. The first focuses on fast fashion supply chains in which inventory and price are managed in real time to maximize retail cycle revenue. The second is concerned with explosive storage policies in Internet Fulfillment Warehouses (IFW). Fashion products are characterized by short product life cycles and market success uncertainty. An unsuccessful product will often require multiple price discounts to clear the inventory. The first topic proposes a switching solution for fast-fashion retailers who have preordered an initial or block inventory, and plan to use channel switching as opposed to multiple discounting steps. The FFS Multi-Channel Switching (MCS) problem then is to monitor real-time demand and store inventory, such that at the optimal period the remaining store inventory is sold at clearance, and the warehouse inventory is switched to the outlet channel. The objective is to maximize the total revenue. With a linear projection of the moving average demand trend, an estimation of the remaining cycle revenue at any time in the cycle is shown to be a concave function of the switching time. Using a set of conditions the objective is further simplified into cases. The Linear Moving Average Trend (LMAT) heuristic then prescribes whether a channel switch should be made in the next period. The LMAT is compared with the optimal policy and the No-Switch and Beta-Switch rules. The LMAT performs very well and the majority of test problems provide a solution within 0.4% of the optimal. This confirms that LMAT can readily and effectively be applied to real time decision making in a FFS. An IFW is a facility built and operated exclusively for online retail, and a key differentiator is the explosive storage policy. Breaking the single stocking location tradition, in an IFW small batches of the same stock keeping unit (SKU) are dispersed across the warehouse. Order fulfillment time performance is then closely related to the storage location decision, that is, for every incoming bulk, what is the specific storage location for each batch. Faster fulfillment is possible when SKUs are clustered such that narrow band picklists can be efficiently generated. Stock location decisions are therefore a function of the demand arrival behavior and correlations with other SKUs. Faster fulfillment is possible when SKUs are clustered such that narrow band picklists can be efficiently generated. Stock location decisions are therefore a function of the demand behavior and correlations with other SKUs. A Joint Item Correlation and Density Oriented (JICDO) Stocking Algorithm is developed and tested. JICDO is formulated to increase the probability that M pick able order items are stocked in a δ band of storage locations. It scans the current inventory dispersion to identify location bands with low SKU density and combines the storage affinity with correlated items. In small problem testing against a MIP formulation and large scale testing in a simulator the JICDO performance is confirmed

Compaction Algorithms for Non-Convex Polygons and Their Applications

Given a two-dimensional, non-overlapping layout of convex and non-convex polygons, compaction refers to a simultaneous motion of the polygons that generates a more densely packed layout. In industrial two-dimensional packing applications, compaction can improve the material utilization of already tightly packed layouts. Efficient algorithms for compacting a layout of non-convex polygons are not previously known. This dissertation offers the first systematic study of compaction of non-convex polygons. We start by formalizing the compaction problem as that of planning a motion that minimizes some linear objective function of the positions. Based on this formalization, we study the complexity of compaction and show it to be PSPACE-hard. The major contribution of this dissertation is a position-based optimization model that allows us to calculate directly new polygon positions that constitute a locally optimum solution of the objective via linear programming. This model yields the first practically efficient algorithm for translational compaction-compaction in which the polygons can only translate. This compaction algorithm runs in almost real time and improves the material utilization of production quality human-generated layouts from the apparel industry. Several algorithms are derived directly from the position-based optimization model to solve related problems arising from manual or automatic layout generation. In particular, the model yields an algorithm for separating overlapping polygons using a minimal amount of motion. This separation algorithm together with a database of human-generated markers can automatically generate markers that approach human performance. Additionally, we provide several extensions to the position-based optimization model. These extensions enables the model to handle small rotations, to offer the flexible control of the distances between polygons and to find optimal solution to two-dimensional packing of non-convex polygons. This dissertation also includes a compaction algorithm based on existing physical simulation approaches. Although our experimental results showed that it is not practical for compacting tightly packed layouts, this algorithm is of interest because it shows that the simulation can speed up significantly if we use geometrical constraints to replace physical constraints. It also reveals the inherent limitations of physical simulation algorithms in compacting tightly packed layouts. Most of the algorithms presented in this dissertation have been implemented on a SUN SparcStationTM and have been included in a software package licensed to a CAD company.Engineering and Applied Science

Assembly Line

An assembly line is a manufacturing process in which parts are added to a product in a sequential manner using optimally planned logistics to create a finished product in the fastest possible way. It is a flow-oriented production system where the productive units performing the operations, referred to as stations, are aligned in a serial manner. The present edited book is a collection of 12 chapters written by experts and well-known professionals of the field. The volume is organized in three parts according to the last research works in assembly line subject. The first part of the book is devoted to the assembly line balancing problem. It includes chapters dealing with different problems of ALBP. In the second part of the book some optimization problems in assembly line structure are considered. In many situations there are several contradictory goals that have to be satisfied simultaneously. The third part of the book deals with testing problems in assembly line. This section gives an overview on new trends, techniques and methodologies for testing the quality of a product at the end of the assembling line

Optimal Packing of Irregular 3D Objects For Transportation and Disposal

This research developed algorithms, platforms, and workflows that can optimize the packing of 3D irregular objects while guaranteeing an acceptable processing time for real-life problems, including but not limited to nuclear waste packing optimization. Many nuclear power plants (NPPs) are approaching their end of intended design life, and approximately half of existing NPPs will be shut down in the next two decades. Since decommissioning and demolition of these NPPs will lead to a significant increase in waste inventory, there is an escalating demand for technologies and processes that can efficiently manage the decommissioning and demolition (D&D) activities, especially optimal packing of NPP waste. To minimize the packing volume of NPP waste, the objective is to arrange irregular-shaped waste objects into one or a set of containers such that container volume utilization is maximized, or container size is minimized. Constraints also include weight and radiation limits per container imposed by transportation requirements and the waste acceptance requirements of storage facilities and repositories. This problem falls under the theoretical realm of cutting and packing problems, precisely, the 3D irregular packing problem. Despite its broad applications and substantial potential, research on 3D irregular cutting and packing problems is still nascent, and largely absent in construction and civil engineering. Finding good solutions for real-life problems, such as the one mentioned above, through current approaches is computationally expensive and time-consuming. New algorithms and technologies, and processes are required. This research adopted 3D scanning as a means of geometry acquisition of as-is 3D irregular objects (e.g., nuclear waste generated from decommissioning and demolition of nuclear power plants), and a metaheuristics-based packing algorithm is implemented to find good packing configurations. Given the inefficiency of fully autonomous packing algorithms, a virtual reality (VR) interactive platform allowing human intervention in the packing process was developed to decrease the time and computation power required, while potentially achieving better outcomes. The VR platform was created using the Unity® game engine and its physics engine to mimic real-world physics (e.g., gravity and collision). Validation in terms of feasibility, efficiency, and rationality of the presented algorithms and the VR platform is achieved through functional demonstration with case studies. Different optimal packing workflows were simulated and evaluated in the VR platform. Together, these algorithms, the VR platform, and workflows form a rational and systematic framework to tackle the optimal packing of 3D irregular objects in civil engineering and construction. The overall framework presented in this research has been demonstrated to effectively provide packing configurations with higher packing efficiency in an adequate amount of time compared to conventional methods. The findings from this research can be applied to numerous construction and manufacturing activities, such as optimal packing of prefabricated construction assemblies, facility waste management, and 3D printing

Key performance indicators for sustainable manufacturing evaluation in automotive companies

The automotive industry is regarded as one of the most important and strategic industry in manufacturing sector. It is the largest manufacturing enterprise in the world and one of the most resource intensive industries of all major industrial system. However, its products and processes are a significant source of environmental impact. Thus, there is a need to evaluate sustainable manufacturing performance in this industry. This paper proposes a set of initial key performance indicators (KPIs) for sustainable manufacturing evaluation believed to be appropriate to automotive companies, consisting of three factors divided into nine dimensions and a total of 41 sub-dimensions. A survey will be conducted to confirm the adaptability of the initial KPIs with the industry practices. Future research will focus on developing an evaluation tool to assess sustainable manufacturing performance in automotive companies