operational problem
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2021 ◽  
Vol 24 (1) ◽  
pp. 89-99
Author(s):  
Jolanta Janutėnienė ◽  
Marijonas Bogdevičius ◽  
Valdas Jankūnas ◽  
Jūratė Janutėnaitė-Bogdanienė ◽  
Arūnas Andziulis ◽  
...  

The operational problem of container unloading from the ship is analyzed in this paper. Dynamic “crane-cargo-ship” system was investigated, and a mathematical model was created. In the model, the gap between the container and the ship’s cargo hold, the mass of the cargo, the container’s center of the mass, and the frictional forces that may occur during lifting from the cargo hold were estimated. Numerical analysis of the system was performed. Results of numerical analysis were compared with experimental measurements of containers unloading process in port. Requirement of lifting power was modelled depending on mass of cargo. Additional power needs in case of contact forces between container and wall of the ship’s cargo hold were calculated. Rational lifting conditions could be deduced using a created mathematical model and the reliability of the container and cargo during lifting could be deduced.


Author(s):  
Karsten Schroer ◽  
Wolfgang Ketter ◽  
Thomas Y. Lee ◽  
Alok Gupta ◽  
Micha Kahlen

We study a novel operational problem that considers vehicle positioning in on-demand rental networks, such as car sharing in the wider context of a competitive market in which users select vehicles based on access. Existing approaches consider networks in isolation; our competitor-aware model takes supply situations of competing networks into account. We combine online machine learning to predict market-level demand and supply with dynamic mixed integer nonlinear programming. For evaluation, we use discrete event simulation based on real-world data from Car2Go and DriveNow. Our model outperforms conventional models that consider the fleet in isolation by a factor of two in terms of profit improvements. In the case we study, the highest theoretical profit improvements of 7.5% are achieved with a dynamic model. Operators of on-demand rental networks can use our model under existing market conditions to build a profitable competitive advantage by optimizing access for consumers without the need for fleet expansion. Model effectiveness increases further in realistic scenarios of fleet expansion and demand growth. Our model accommodates rising demand, defends against competitors’ fleet expansion, and enhances the profitability of own fleet expansions.


2021 ◽  
Author(s):  
Grahame Taylor ◽  
Jonathan Wylde ◽  
Walter Samaniego ◽  
Ken Sorbie

Abstract Despite attempts to inhibit or avoid the formation of fouling deposits (polymeric amorphous dithiazine or apDTZ for short) from the use of MEA triazine, this remains a major operational problem and limits the use of this most popular and ubiquitous hydrogen sulphide (H2S) scavenger. This paper (a) reviews and summarizes previous work, (b) provides fresh insights into the reaction product and mechanism of formation, (c) proposes an effective method of removal, and (d) proposes some mechanisms of apDTZ digestion. The mechanism of apDTZ formation is discussed and reasoning is provided from a variety of perspectives as to the mechanism of MEA-triazine reaction with H2S. These include basicity and nucleophilic substitution considerations, steric properties and theoretical calculations for electron density. Novel procedures to chemically react with and destroy this solid fouling are presented with an in-depth study and experimental verification of the underlying chemistry of this digestion process. A review of agents to chemically destroy apDTZ is undertaken and a very effective solution has been found in peroxyacetic acid, which is much more powerful and effective than previously suggested peroxides. The structure of amorphous polymeric dithiazine is emphasized and the reason why this fouling cannot be 1,3,5-trithiane is stressed. This work therefore overcomes a current industry misconception by providing insight on two major paradoxes in the reaction pathway; namely i) why the thiadiazine reaction product from tris hydroxyethyl triazine (MEA triazine) is never observed and ii) why does the dithiazine in all cases never progress to the trithiane (3rd sulphur molecule substitution)? The latter issue is probably the biggest misconception in the industry and literature regarding triazine and H2S reactions. Many reasons for this are put forward and the common misconception of "overspent" triazine is refuted. A very effective chemical reaction that results in soluble by-products, counteracting the problems produced by this intractable polymer is found and their composition is proposed and experimentally verified.


Author(s):  
Priyandoko Gigih ◽  
Mohd Fairusham Ghazali

Nowadays, a piping system is one of the important features in either home or industrial user. Leak in piping systems is a major operational problem around the world.  Leaks result to loss in the fluid through the flow and automatically affect to the economy of the user. Objective of this research is utilizing the signal processing using Wavelet Transform and Cepstrum Analysis methods to leak detect in pipeline. After experiment has been completed, the data analysis process by using Matlab Software takes place. The result shows that the accuracy of the leak location detection is accurate with small error results below 10%.


2021 ◽  
Vol 5 ◽  
Author(s):  
Bibiana Ramírez-Pulido ◽  
Claudia Bas-Bellver ◽  
Noelia Betoret ◽  
Cristina Barrera ◽  
Lucía Seguí

Food waste is a worldwide concern as it represents a constant threat to the environment and a serious operational problem for the food industry. The by-products of fruits and vegetables being a valuable source of bioactive compounds have the potential to be reused and reintroduced in the agri-food chain. This circular approach contributes to a sustainable production system. In this context, a collaborative project with the primary sector for the integral valorization of the waste generated in the fresh-processing vegetable lines of an agricultural cooperative is currently being developed, particularly focused on cabbage, carrot, celery, and leek. The objective of this project is to transform vegetable wastes into functional powdered ingredients and be able to use them in food formulations in order to improve the nutritional profile of foods, contributing to the development of sustainable healthy diets. Through an exhaustive bibliographic review, this research studies the influence of pretreatments, drying and in vitro digestion on the bioactive compounds of vegetable residues, with the aim of identifying the appropriate production parameters to achieve an adequate functional and physicochemical profile of the final powders.


2021 ◽  
Vol 13 (1) ◽  
pp. 29-44
Author(s):  
Manuel F. Suárez-Barraza ◽  
José Angel Miguel-Dávila ◽  
Manuel Francisco Morales-Contreras

Purpose The purpose of this paper is to explore, study, analyze and implement Kaizen–Kata methodology in a service food organization (first-level restaurant), facing challenges in different operational processes that affect and influence the case company performance and customer satisfaction. Design/methodology/approach The service organization implemented Kaizen–Kata methodology to improve one operational problem process. A case-study approach was used in this research to understand the effects of the Kaizen–Kata methodology in solving problems in their operational service process. Different Kaizen–Kata techniques and tools (histograms, Pareto chart and Ishikawa diagram) using the Plan, Do, Check, Act improvement cycle framework were used. Findings Successful implementation of the proposed methodology reduced the main impact of the problem’s effects (customer’s complaints, process reworking, extra-cost, delays, among others). The effects of the problem were reduced on average by 70%. Some Kaizen–Kata routines were identified in a service process environment. Research limitations/implications The main limitation of the research is that this work is a just one-case study. A main generalization is not possible, because it involves a company within a company. Practical implications Some other service companies can use the Kaizen–Kata methodology to solve any kind of operational problem within their processes. Service managers can learn about the methodology to apply and improve their operational performance and handle customer’s complaints. Originality/value A continuous improvement manufacturing methodology was imported to apply in an operational service process. The Kaizen–Kata methodology contributed significantly to reduce delays, handle customer’s complaints, process reworking and deal with extra costs, among other operational problems’ effects. In addition to that, in the literature, most of the Kaizen applications are in manufacturing companies. To the best of authors’ knowledge, this was the first study of applied Kaizen–Kata in a service organization (a fast-food restaurant).


Author(s):  
Manuel F. Suárez-Barraza ◽  
José A. Miguel-Davila

Purpose: Mexico’s public hospitals are experiencing major operational problems which seriously affect the care of Mexican citizens. Some hospitals have initiated efforts to apply the Kaizen philosophy to improve this situation. Therefore, the purpose of this article is to analyze the methodological impact of Kaizen–Kata implementation in Mexican public hospitals that have tried to solve operational problems using this improvement approach. Design/Methodology/Approach: The service organization implemented Kaizen–Kata methodology in order to improve one operational problem-process in health care. A case-study approach was used in this research in order to understand the effects of the Kaizen–Kata methodology in solving problems in their operational procedures. Findings: Six specific drivers were identified when applying the Kaizen–Kata methodology. Furthermore, the impact on the levels of implementation of the Kaizen–Kata methodology in each of the improvement teams studied was also identified. Research Limitations: The main limitation of the research is that only three case-studies are presented thus it is not possible to generalize its results. Practical Implications (Where Possible): Other public hospitals can use this specific example as a working guide to solve the operational problems of health systems. Originality/Value: A methodology of continuous improvement in manufacturing was imported from the industry sector for application in an operational health care process. The Kaizen–Kata methodology contributed significantly to improving issues involving delays, customer complaints, process reworks and extra-cost, among other effects of operational problems.


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