Changeover Time Research Articles

Integrated production-distribution scheduling with energy considerations for efficient food supply chains

Abstract Quantitative approaches for the integration of production and distribution planning are attracting the interest of scholars and companies in recent years. They can significantly improve supply chain performance and sustainability. In this paper, we propose an optimization model for the integrated scheduling of production and distribution activities, with reference to a real-life company in the food sector. The model takes into consideration changeover times and perishability, and aims to jointly minimize energy, storage and distribution costs. Its applicability is shown through a set of computational experiments, carried out on instances generated from historical data. Two different rescheduling strategies, where the first one reproduces the current behaviour of the firm, are compared. The results show that the current practices of the company can be improved and the model is a valid tool for supporting operational business decisions.

A Generic Plug & Produce System Composed of Semantic OPC UA Skills

Typical industrial workcells are composed of a plenitude of devices from various manufacturers, which rely on their own specific control interfaces. To reduce setup and reconfiguration times, a hardware-agnostic Plug & Produce system is required. In this paper, we present a system architecture that uses generic and semantically augmented OPC UA skills for robots, tools, and other system components. Standardized skill interfaces and parameters facilitate flexible component interchange and automatic parametrization with a focus on reusability of skills across different platforms and domains. The hierarchical composition of such skills allows for additional abstraction through the grouping of functionalities. Through the extension of OPC UA discovery services, available skills are dynamically detected whenever a manufacturing system's component is updated. The introduced Plug & Produce system is evaluated in multiple industrial workcells composed of robots, tool changer, electric parallel gripper, and vacuum gripper-all controlled via the proposed OPC UA skill interface. The evaluation of our system architecture demonstrates the applicability of the Plug & Produce concept in the domain of robot-based industrial assembly. Although it is necessary to adapt existing hardware to comply with the semantic skill concept, the initial one-time effort yields reoccurring efficiency gains during system reconfiguration. In particular, small lot production benefits from reduced changeover times.

Theoretical prerequisites for improving the body low loader granular fertilizer spreader

It is known that the use of granular forms of fertilizers is a universal solution for plant growing enterprises using organic, mineral, organomineral fertilizers in their activities. For crop farming enterprises, the application of granular fertilizers is the most convenient way to enrich the soil with nutrients. For the surface main application and top dressing, spreaders of different designs are used, distributing fertilizers in a continuous layer with different indicators of uniformity. At present, the development of machines of various designs is underway to operate applying solid fertilizers. The main tasks of research by various authors in the field of mechanization of the distribution of fertilizers over the surface of the field are to reduce the uneven distribution of fertilizers across the width, increase the sowing width, as well as reduce the changeover time for the fertilization operation. The article presents studies related to the improvement of the design of the working bodies of the machine for applying granular fertilizers, installed on the horizontal axis of rotation. To achieve the goal of increasing the working width of the unit without reducing the quality of the sifting, an option was proposed to supplement the design of a low-frame body spreader for solid fertilizers.

Fluid Automation — A Definition and an Application in Remanufacturing Production Systems

Production systems must be able to quickly adapt to changing requirements. Especially in the field of remanufacturing, the uncertainty in the state of the incoming products is very high. Several adaptation mechanisms can be applied leading to agile and changeable production systems. Among these, adapting the degree of automation with respect to changeover times and high investment costs is one of the most challenging mechanisms. However, not only long-term changes, but also short-term adaptations can lead to enormous potentials, e.g. when night shifts can be supported by robots and thus higher labor costs and unfavorable working conditions at night can be avoided. These changes in the degree of automation on an operational level are referred to as fluid automation, which will be defined in this paper. The mechanisms of fluid automation are presented together with a case study showing its application on a disassembly station for electrical drives.

Okvir za dizajniranje optimizovanog sistema proizvodnje baziranog na optimizovanoj funkcionalnosti i integraciji kriterijuma u fazi dizajniranja proizvodnih mašina

Manufacturing needs more and more requirements (sustainability, agility, Industry 4.0 technologies, etc.) to meet customer demands. Nowadays, companies apply Lean tools to improve machines and systems performance in their use phase. Lean tools application on existing machines ensures some functionalities like (Reduce changeover time, eliminate wastes, Involve Human Skills, etc.). The purpose of this paper is to offer designers a design support method and tool to design a performant system (production system, machines, etc.) by integrating Lean functionalities from the early design phases, with a minimum of needs to improve the system in the use phase via Lean. For this purpose, we analyze the Lean principles and tools to identify functionalities provided by Lean. These functionalities are analyzed and classified to integrate them into the design of manufacturing systems in the context of Industry 4.0. A "Lean-System-Design" approach defines a systematic and detailed guide for the integration of Lean from the early design phase. We provide the software tool specifications, which represent the first steps of its implementation. We have illustrated our proposal with a case study on the design of a waste treatment machine.

THE APPLICATION OF SMED METHOD IN THE INDUSTRIAL ENTERPRISE

The production process fluency is often interrupted by idle time. A significant proportion of individual idle times is caused by changeover. Trends, such as the individualization of requirements, the constant effort to meet the customers’ requirements on time and the maintaining of the production process fluency at low costs, are aimed at eliminating idle time. In terms of contradictory goals such as individualization of customer requirements, which is reflected in the high variability of production / products and minimalization of the production time and its fluency, it is necessary to pay increased attention to the changeover process. The problem related to the changeover process can be solved in two ways: by reducing the number of changeovers (reducing production variability and achieving dissatisfaction with individual customer requirements) or by shortening the changeover time (while maintaining production variability and ability to satisfy a wide range of individual customer requirements). The Single-Minute Exchange of Die - SMED method is used to shorten the time duration of the changeover process and eliminate waste in the given process. The aim of the paper is to apply the SMED method in vibration welder changeover process in a selected industrial enterprise and thus achieve a shortening of the changeover process. The SMED method was applied in the enterprise which belongs to the group of small and medium-sized enterprises. The research method was indirect observation via video recording and time snap. Various types of waste were identified based on the analysis, and subsequently eliminated by proposed rationalization measures. Finally, the time duration of the changeover process before the analysis and after the implementation of rationalization measures was compared.

Estimation of machine setup and changeover times by survival analysis

The losses associated with changeovers are becoming more significant in manufacturing due to the high variance of products and requirements for just-in-time production. The study is based on the single minute exchange of die (SMED) philosophy, which aims to reduce changeover times. We introduced a method for the analysis of these losses based on models that estimate the product- and operator-dependent changeover times using survival analysis. The root causes of the losses are identified by significance tests of the utilized Cox regression models. The resulting models can be used to design a performance management system that considers the stochastic nature of the work of the operators. An anonymized manufacturing example related to the setup of crimping and wire cutting machines demonstrates the applicability of the method.

A Kinematics Comparison of Different Swimming Relay Start Techniques

ABSTRACT In swimming relay races, various start techniques are performed by swimmers, but it remains unclear which technique leads to a better start performance. Therefore, the purpose of the present study was to compare the kinematic characteristics of different relay start techniques with the new starting block Omega OSB11. Eleven international youth swimmers were filmed during 1) no step with parallel feet, 2) no step with separated feet and 3) one-step starts and their centre of mass kinematics calculated with 2D-DLT algorithms. Results indicate that differences between techniques were detected in the spatiotemporal parameters of the block and aerial start phases (e.g., initial and take-off positions, entry height, preparation and changeover times) and in selected parameters of the underwater phase (e.g., emersion time and distance, underwater time and distance). However, no statistical effects were found in 5 m, 10 m and 15 m start times, nor in horizontal take-off velocity, despite an observed trend for the one-step start to be superior to the non-step techniques. These results suggest that differences between relay techniques could rely more on the swimmer’s body posture (angular kinematics) on the block, flight and underwater phases than on the centre of mass linear kinematics.

Exploring a two-product unreliable manufacturing system as a capacity constraint for a two-echelon supply chain dynamic problem

ABSTRACT In this paper, we investigate a two-echelon, two-product Supply Chain (SC) inspired by a real-world production/distribution firm, in which the product change-over time, necessary to switch from a product to another, induces a variable capacity in the factory. Such a varying production capacity is further exacerbated by the machine breakdowns that may occur in the manufacturing system. Since the two products share the same production system, a production planning rule has to be executed to decide the change-over, i.e. to select the product to be manufactured over time. An extended experimental campaign has been performed to investigate how the fill rate and the standard deviation of inventories vary as a series of operational and tactical parameters changes. Several ANOVA analyses revealed a strong interaction between the production planning model and the adopted smoothing replenishment strategy, which remarkably affects the performance of the SC. Interestingly, a higher value of the proportional controller negatively affects the service levels since the adopted production planning policy, under these circumstances, tends to encourage longer production runs for a certain product and, consequently, persistent stock outs for the other one.

Sustainable Production Flexible Improvement by Internal Activities Time Reduction in Manufacturing Industry

Nowadays, the manufacturing sectors are in the process of increasing their performance to extend productivity because there are so many challenges from competitors in the same sectors, especially in the food industry. The purpose of this study is to propose improvements to increase sustainability of food operation flexibility through secondary data collection, Cause and effect diagram analysis, and the Why-why Analysis tool. Besides, improving the understanding of Single Minute Exchange of Dies (SMED) factors in the production line can be applied by changing the internal activities to become external activities. This study is useful for manufacturing managers and companies who are willing to increase their flexibility and at the same time reduce the changeover time within their available resources without compromising the machine efficiency and cost. In conclusion, this study has provided a better understanding of reducing internal activities that cause high changeover time.

Design of framework of Hybrid RMS for Ball Manufacturing Industry

This paper discusses the possibility of implementation of a reconfigurable manufacturing system to aid a manufacturing organization to manufacture tennis and rubber balls simultaneously or exclusively with minimum changeover time. The tennis balls and rubber balls come under a single part family, that is, Ball. They constitute 8 types of products in total. The proposed manufacturing system consists of three individual and parallel manufacturing lines that are capable of manufacturing both tennis and rubber balls. As per the change in demand, the line can be reconfigured to manufacture any product within the part family.

Dietary patterns and cognitive decline among older adults: Findings from Sydney Memory and Aging Study

AbstractBackgroundEvidence suggested dietary patterns that may protect against cognitive decline among older adults, are mostly plant‐based, rich in poly‐/mono‐ unsaturated fatty acids, and low in processed foods. We aim to examine associations between diet with cognition and cognitive decline among older adults over a 6‐year period in Sydney Memory and Aging Study.MethodCommunity dwelling participants (n=1037) were non‐demented and aged 70‐90 years at baseline. Diet was assessed using the 80‐item Cancer Council of Victoria FFQ at baseline, Mediterranean diet scores and DASH diet scores were generated based on dietary intake for individuals. Using PCA we have derived a‐posterori patterns. Neuropsychological tests assessed global cognition and 6 cognitive domains for 4 times, at baseline and followed up every two years. Linear mixed model analyses were conducted to examine the relationship between dietary scores, cognitive health, and cognition change over time, with adjustment for age, gender, education, BMI, cardiovascular risk factors, history of stroke, smoking, depression and APOE ε4 genotype.ResultNo significance was found between adherence to Mediterranean diet or DASH diet, and cognitive decline over 6 years. However, a total intake of legumes and nuts, was positively associated with better overall performance in cognitive domains including language (β=0.058; 95% CI: 0.028, 0.113; P=0.040), visuospatial (β=0.048; 95% CI: 0.008, 0.089; P=0.019) and global cognition (β=0.059; 95% CI:0.005, 0.112; P=0.033). The prudent healthy diet pattern was associated with cognitive health in women over time, in domains of memory (β=0.332; 95% CI: 0069, 0.596 ; P=0.014), verbal memory (β=0.313; 95% CI:0.056 ,0.569 ; P=0.017), visuospatial (β=0.271; 95% CI: 0.005,0.440; P=0.009), executive (β=0.352; 95% CI:0.073, 0.631; P=0.014), attention processing speed (β=0.273; 95% CI: 0.039,0.507 ; P=0.022) and global cognition (β=0.426; 95% CI: 0.141,0.711 ; P=0.004).ConclusionIn this longitudinal analysis, a prudent healthy diet and high total intake of legumes and nuts, were associated with better cognitive performance over 6 years in various domains among older adults. Adherence to Mediterranean or DASH diet was not associated with cognitive change overtime.

A computational optimization method for scheduling resource-constraint sequence-dependent changeovers on multi-machine production lines

This paper presents an algorithmic method that hybridizes solution procedures with an optimization model for solving the problem of scheduling and allocating changeover tasks. This problem involves a limited number of changeover workers with different skills and a set of sequence-dependent changeover tasks on a multi-machines production line, where executing each task requires a particular type and number of workers. For solving this allocation and scheduling problem, the paper identifies and investigates three priority rules expressed as objective functions to minimize the total changeover time and maximize the workers' utilization while satisfying changeover task-sequence-dependency and worker-limit constraints. For illustrating the applicability and suitability of the proposed approach, a real-world case problem of a 10-machine production line is considered for scheduling and allocating 34 sequence-dependent changeover tasks to 4 workers. The computational effort and time for optimizing each of the three identified objective functions using the proposed method were significantly undersized. The key results are the effective changeover time and workers' utilization provided by the proposed hybrid approach.

Abstract 15473: Effect of Statins on Coronary Plaque Progression Assessed by Serial Coronary Computed Tomography Angiography

Introduction: Statins stabilize coronary plaques and reduce clinical events. However, it is unclear how statins change the total plaque burden and plaque morphology. Hypothesis: We aimed at investigating whether statin users have less coronary plaque progression compared to non-statins users. Methods: We identified 243 subjects undergoing serial computed tomography angiography, 163 taking statins and 80 who are not. Coronary plaque (total, calcified, non-calcified including fibrous, fibrous-fatty and low-attenuation plaque (LAP)) volume was measured using semi-automated plaque software (Qangio, Medis) and its change overtime between statins users and non-statins users was evaluated using Analysis of Covariance (ANCOVA) modeling adjusted for age, gender, diabetic status, presence of hypertension, past smoking use, and baseline plaque levels. Results: Subjects on statin therapy had higher body mass index, were more likely to be diabetic, had hyperlipidemia, and were past smokers. Median coronary artery calcium score was significantly lower in the statin group; p<0.034. Driven primarily by changes in fibrous plaque, those on statin therapy showed 25% less total plaque (P=0.013) and 31% less total non-calcified plaque (P=0.006) at follow-up than non-statin users. Conclusions: The current study indicates that statin use is associated with less progression of total plaque and total non-calcified plaque burden.

Advances in Machine Learning Detecting Changeover Processes in Cyber Physical Production Systems

The performance indicator, Overall Equipment Effectiveness (OEE), is one of the most important ones for production control, as it merges information of equipment usage, process yield, and product quality. The determination of the OEE is oftentimes not transparent in companies, due to the heterogeneous data sources and manual interference. Furthermore, there is a difference in present guidelines to calculate the OEE. Due to a big amount of sensor data in Cyber Physical Production Systems, Machine Learning methods can be used in order to detect several elements of the OEE by a trained model. Changeover time is one crucial aspect influencing the OEE, as it adds no value to the product. Furthermore, changeover processes are fulfilled manually and vary from worker to worker. They always have their own procedure to conduct a changeover of a machine for a new product or production lot. Hence, the changeover time as well as the process itself vary. Thus, a new Machine Learning based concept for identification and characterization of machine set-up actions is presented. Here, the issue to be dealt with is the necessity of human and machine interaction to fulfill the entire machine set-up process. Because of this, the paper shows the use case in a real production scenario of a small to medium size company (SME), the derived data set, promising Machine Learning algorithms, as well as the results of the implemented Machine Learning model to classify machine set-up actions.

Mathematical modelling of sleep and sleepiness under various watch keeping schedules in the maritime industry

Ships typically operate on a 24/7 basis giving rise to a wide variety of working time arrangements and watch keeping schedules. Typically, these can be divided into 2-watch systems (where two watch keepers/teams share the 24-h period) and 3-watch systems (where three watch keepers/teams share the 24-h period). The current study uses the three-process model of alertness regulation to compare these systems in terms of the amount of severe sleepiness that is predicted to take place on watch and the amount of sleep that is predicted to occur while off watch. Separate predictions are calculated for individuals characterised as morning and evening chronotypes. Comparing 2-watch systems, highest levels of severe sleepiness were seen for evening types working 0000–1200 within the 12on12off system. The longest sleep per 24 h day was also found for evening types, but for those working the 1200–0000 watch within the 12on12off system. Total daily sleep duration ranged between 268 and 445 min. However, the picture is complex and the lowest risk of severe sleepiness while on watch is not necessarily correlated with the maximal time available for rest and recuperation when off watch. For 3-watch systems, the “five-and-dime” system (changeover times: 02-07-12-17-22) stands out having the lowest prevalence of severe sleepiness on watch and the longest amount of predicted daily sleep off watch. Considerable differences exist between morning and evening types offering the opportunity for considerable improvement in sleep amount for fixed (but not rotating) systems when individual chronotype is considered in watch scheduling. It is concluded that 3-watch systems, although economically costlier, have clear advantages over 2-watch systems, but that a perfect system that fits all does not exist due to the considerable impact of individual differences related to sleep/wake regulation.

The Multi-Spreader Crane Scheduling Problem: Partitions and supersequences

In the Multi-Spreader Crane Scheduling Problem (MSCSP), containers with identical dimensions but variable weights are arranged along a grid. A multi-spreader crane is used to lift all the containers. The crane has m>1 modes. When it is in the pth mode, the crane can remove p adjacent containers along the same row at the same time as long as the total weight of the containers does not exceed the loading capacity κp. Such a lift takes hp minutes. It also takes cp,q minutes for the crane to switch from mode p to q when p≠q. The goal is to find a crane lift sequence so that the total time it takes to lift all the containers is minimized.This paper investigates the computational complexity of MSCSP. First, we establish a connection between greedy crane lift sequences and supersequences. We then prove that MSCSP is NP-hard when the crane has three or more modes by a reduction from a version of the Shortest Common Supersequence problem. Lastly, we investigate two problems that arise naturally when heuristics are used to solve MSCSP. We show that one can be solved using dynamic programming while the other remains computationally hard. We also provide an approximation algorithm that behaves nicely when the changeover times are not much larger than the lifting times of the crane.

Differences in Human Milk Lactose and Citrate Concentrations Based on Gestational Diabetes Status.

Background: Exclusive breastfeeding is the optimal manner of early infant nutrition but women with gestational diabetes mellitus (GDM) often experience challenges with lactation in the early postpartum period. Increases in the colostral metabolites of lactose and citrate have been found to indicate increased milk production. Materials and Methods: A follow-up study of 133 postpartum women with and without GDM was conducted to examine differences in specific colostral metabolite levels using enzymatic methods to determine transition to lactogenesis II during the first week postpartum. We used linear mixed models for repeated measures over time to examine the effect of GDM on colostral metabolite levels at baseline and follow-up with fixed effects of GDM status, time, covariates, and interactions between time and GDM, between time and time, and between time, time and GDM into the model allowing quadratic trends over time. Results: Over time, lactose and citrate levels increased for all mothers (p < 0.001 and p < 0.001, respectively), although mothers with GDM had consistently lower lactose and citrate levels compared with nondiabetic mothers (p = 0.004 and p = 0.014, respectively). Age, prepregnancy body mass index, mode of birth, and parity did not independently influence colostral concentrations of lactose and citrate. Conclusions: Findings suggest that the rate of change overtime in lactose and citrate concentrations differ by GDM status. Further research examining the trajectory of colostral metabolite levels by GDM status is warranted.

Trends in Complications Among Benign Hysterectomy Patients in Relation to BMI

Study Objective To evaluate complication rates and length of stay over time in relation to BMI to assess for improvements in care given the increasing need to take care of obese women. Design Retrospective cohort study. Setting American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database. Patients or Participants Strict criteria were used to include planned benign hysterectomies without confounding concomitant procedures from 2010 to 2018. Interventions Chi-squared analysis was used to analyze the relationship between complications (wound, length of stay, readmission, etc) and time stratified by BMI categories using CDC criteria and type of hysterectomy (abdominal, laparoscopic, or vaginal). Measurements and Main Results 204,111 hysterectomies met inclusion criteria. Overall length of stay decreased overtime from 1.7 days in 2010-2011 to 1.4 days in 2017-2018 (p 40 undergoing abdominal hysterectomy who had a decrease in overall complication rate from 16.5% in 2010-210 to 12.5% in 2017-2018 (p=0.01). Prolonged length of stay (greater than 2 days) decreased overtime for normal weight, overweight, and Class 1-3 obese women specifically for abdominal and laparoscopic hysterectomies (p Conclusion Irrespective of hysterectomy type and BMI, length of stay is decreasing without differences in readmission rates. Overall, complications rates do not demonstrate significant change overtime. Further analysis is required to determine if this trend will continue and how outcomes can be improved for obese patients.

A new mathematical formulation for a potash-mine shift scheduling problem with a simultaneous assignment of machines and workers

In this paper, we introduce a mixed-integer linear program for a shift scheduling problem in a German potash mine. In particular, we consider a short-term (work shift) production scheduling problem, where drill-and-blast mining operations have to be assigned to machines and workers simultaneously. Since we deal with several sequence-dependent setup, changeover, and removal times, TSP-variables are used in the mathematical program to determine the processing-sequence of the operations on each worker and each machine, respectively. In addition, several mining-specific requirements are taken into account to obtain a solution that can be put into practice. Computational experiments are conducted on problem instances of realistic size derived from real-world data. The results show that our new mixed-integer linear formulation outperforms both existing solution procedures for the problem at hand.