The problem of consolidation of soil has been widely investigated. The basic approach was given by Terzaghi who assumed soil of constant physical and mechanical parameters. In the case of peat consolidation, the permeability coefficient of soil and the elasticity modulus are functions of the settlement which is an important additional factor. The model proposed here assumes varying the elasticity and permeability coefficients. Moreover, the settlement is described by the so-called elementary curve which was approximated empirically based upon laboratory tests. The model allows to consider the case when the filtration in the peat body goes in horizontal direction. It happens so when the charging layer does not receive outgoing water from the pores. The model includes also the case when the load involving consolidation varies in time i.e. the charging layer grows up gradually. The model has been applied practically in several cases and it comes that there is a good agreement between calculated and measured settlement of the consolidated peat layer.
This paper presents a method for assessing the degree of approaching the paper output of the Clausius-Rankine cycle to the Carnot cycle. The computations to illustrate its use were performed for parameters characteristic of the current state of development of condensing power plants as well as in accordance with predicted trends for their further enhancing. Moreover there are presented computations of energy dissipation in the machines and devices working in such a cycle.
Many business offices around the world are organized as open plan offices. Therefore, studies about the acoustic comfort of the people who work in them have become increasingly important. The focus of this work is the acoustic evaluation of an open plan office combining several architectural characteristics and levels of ambient noise. This evaluation was performed through a computational model calibrated from a real office. The rate of spatial decay of sound pressure levels per distance doubling (DL2) and the speech transmission index (STI) were simulated for the acoustic evaluation of the office, allowing for the determination of the radius of distraction (rD). These parameters were simulated for 6 situations using different floor and ceiling covering materials and inserting or withdrawing screens between workstations. In addition, STI and rD were simulated under two conditions of ambient noise. The results indicated that the DL2 and rD are adequate acoustic parameters for the acoustic evaluation and improvement of an open plan office. The DL2 was strongly influenced by the presence or absence of screens between workstations and by the ceiling covering material. The rD was more sensitive to changes in ambient noise.
In a reality of global competition, companies have to minimize production costs and increase productivity in order to boost com-petitiveness. Facility layout design is one of the most important and frequently used efficiency improvement methods for reducing operational costs in a significant manner. Facility layout design deals with optimum location of facilities (workstation, machine, etc.) on the shop floor and optimum material flow between these objects. In this article, the objectives and procedure of layout design along with the calculation method for layout optimization are all introduced. The study is practice-oriented because the described case study shows how the layout of an assembly plant can be modified to form an ideal re-layout. The research is novel and innovative because the facility layout design and 4 lean methods (takt-time design, line balance, cellular design and one-piece flow) are all combined in order to improve efficiency more significantly, reduce costs and improve more key performance indicators. From the case study it can be concluded that the layout redesign and lean methods resulted in significant reduction of the following seven indicators: amount of total workflow, material handling cost, total travel distance of goods, space used for assembly, number of workers, labor cost of workers and the number of Kanban stops.
Lean has established itself as the primordial approach to obtain operational excellence. Its simple and intuitive techniques focus on reducing lead time through continuous improvement, involving all levels of employees in the organization. However, the rate of successful implementations has remained low. This paper contributes to the understanding of continuous improvement in a Lean context, by analyzing a database of almost 10.000 improvement actions, from 85 companies, covering the time frame 2010–2018. It discusses categories of actions, their impact and cost, as well as key characteristics of the companies. It proposes an objective criterion to identify “success” and “failure” in Lean implementation and tries to link these to operational results. It is probably the first time an analysis of this magnitude on the subject has been performed.
The purpose of the paper is to present the author’s reflections on the origin and popularity
of various approaches to maintenance and improvement of production processes, their
terminological consistency, understanding, and practical application of their principles. The
author’s reflections are based on his observations made over his many years of activity as
a lecturer and consultant in the area of production engineering and management. It was
shown that there is a need to make scientists and practitioners aware of the relatively large
degree of freedom in defining the scope and way of application of strategies of continuous
improvement. The author’s proposal is to refer to all approaches to maintenance and improvement
of production processes with the title “Strategies of Efficient Action” and all
supporting methods as “Practices of Efficient Action”.
Considerations presented in the paper can be useful in more and more efficiently applying
the power of TQM, Six Sigma, Lean Manufacturing and other strategies of processes
maintenance and improvement in the daily activities of companies.
The paper presents the technology and organization of the artistic cast production. On the basis of the actual cast production system, the
manufacturing process was shown, in particular sand–piece moulding, which is a very important process and a time-consuming part of the
entire manufacture of the casts. The current state of the production process as well as the organization of the work and production
technology were analysed with the use of methods and techniques of production improvement, the Lean Manufacturing concept and
computer systems. The results of the analysis and studies were shown with use of schemes and graphs of the layout of the production
resources, a flow chart of the production process, value stream mapping, and a costs table for the production and modernization of the
moulding stage. The work has shown that there are possibilities to improve the artistic cast production system. This improvement leads to
increased productivity, lower production costs of artistic casts and increased competitiveness of the foundry.
This study demonstrates application of Lean techniques to improve working process in
a sewing machine factory, focusing on the raw material picking process. The value stream
mapping and flow process chart techniques were utilized to identify the value added activities,
non-value activities and necessary but non-value added activities in the current
process. The ECRS (Eliminate, Combine, Rearrange and Simplify) in waste reduction was
subsequently applied to improve the working process by (i) adjusting the raw material picking
procedures and pre-packing raw material as per demand, (ii) adding symbols onto the
containers to reduce time spent in picking material based on visual control principle, and
(iii) developing and zoning storage area, identifying level location for each row and also
applying algorithms generated from a solver program and linear programming to appropriately
define the location of raw material storage. Improvement in the raw material picking
process was realized, cutting down six out of 11 procedures in material picking or by 55%,
reducing material picking time from 24 to 4 min or by 83%. The distance to handle material
in the warehouse can be shortened by 120 m per time or 2,400 m per day, equal to 86%
reduction. Lean techniques
The radial distribution system is a rugged system, it is also the most commonly used system, which suffers by loss and low voltage at the end bus. This loss can be reduced by the use of a capacitor in the system, which injects reactive current and also improves the voltage magnitude in the buses. The real power loss in the distribution line is the I2R loss which depends on the current and resistance. The connection of the capacitor in the bus reduces the reactive current and losses. The loss reduction is equal to the increase in generation, necessary for the electric power provided by firms. For consumers, the quality of power supply depends on the voltage magnitude level, which is also considered and hence the objective of the problem becomes the multi objective of loss minimization and the minimization of voltage deviation. In this paper, the optimal location and size of the capacitor is found using a new computational intelligent algorithm called Flower Pollination Algorithm (FPA). To calculate the power flow and losses in the system, novel data structure load flow is introduced. In this, each bus is considered as a node with bus associated data. Links between the nodes are distribution lines and their own resistance and reactance. To validate the developed FPA solutions standard test cases, IEEE 33 and IEEE 69 radial distribution systems are considered.
World Class Manufacturing system consists of ten technical and ten managerial pillars.
These, impacting directly and indirectly on each other, generate the flow of internal processes. Two of the mentioned pillars, Early Product Management (EPM) and Cost Deployment
(CD) play a special role in the system, because they create a future strategic management
of a company influencing design engineering, manufacturing and economy [1, 2]. Referring
to the author’s previous publications on Early Product Management methodology [3, 4], the
role of Cost Deployment pillar in the new product launch remains an important issue. Additionally, there is a noticeable lack of publications in this specific field of the WCM system.
Therefore, a proper understanding of the relationship between these two technical pillars
is the basis for effective project management for the implementation of new products. In
this article, the correlation between EPM and CD will be highlighted whereas some critical
remarks will be indicated. The main part of the article will describe: the current approach to
project management according to the standards set by the WCM system and recommended
improvements originated from EPM and CD pillars. The quality scientific methods used in
this article are based on a case study of internal processes in an international plant specializing in agriculture machinery production and include elements of direct observation and
theoretical analysis and synthesis. This paper refers to the presented issues in practical terms
on the example of the methodology of managing of new launch product projects in terms of
cost management. The purpose of this paper is to draw attention to the problem of the cost
factor generated during the design phase and early implementation of the new product into
production, which will enable effective cost management of new implementation projects.
The main purpose of this article is to present an author’s methodology of production levelling
and to show the impact of levelling on the time during which the product passes
through the process and on staff performance. The article presents the analysis of literature
concerning the method of improving the production process, especially taking production
levelling into consideration. The authors focussed on the definition and methodologies of
production levelling. A diagram of interrelations showing determinants and efficiency measures
of production levelling as well as an author’s production levelling methodology have
been presented. An example of the implementation of production levelling in one of the departments
of a company manufacturing surgical instruments has also been shown. Analysis
of the current state, stages of implementation and end effects have been presented. Attention
was focussed on the time during which the product passes through the process and on staff
performance.
There is a general agreement that remembering depends not only on the memory processes as such but rather that encoding, storage and retrieval are under the constant influence of the overarching, metacognitive processes. Moreover, many interventions designed to improve memory refer in fact to metacognition. Most attempts to integrate the very different theoretical and experimental approaches in this domain focus on encoding, whereas there is relatively little integration of approaches that focus on retrieval. Therefore, we reviewed the studies that used new ideas to improve memory retrieval due to a “metacognitive intervention”. We concluded that whereas single experimental manipulations were not likely to increase metacognitive ability, more extensive interventions were. We proposed possible theoretical perspectives, namely the Source Monitoring Framework, as a means to integrate the two, so far separate, ways of thinking about the role of metacognition in retrieval: the model of strategic regulation of memory, and the research on appraisals in autobiographical memory. We identified venues for future research which could address, among other issues, integration of these perspectives.
A transformer is an important part of power transmission and transformation equipment. Once a fault occurs, it may cause a large-scale power outage. The safety of the transformer is related to the safe and stable operation of the power system. Aiming at the problem that the diagnosis result of transformer fault diagnosis method is not ideal and the model is unstable, a transformer fault diagnosis model based on improved particle swarm optimization online sequence extreme learning machine (IPSO-OS-ELM) algorithm is proposed. The improved particle swarmoptimization algorithm is applied to the transformer fault diagnosis model based on the OS-ELM, and the problems of randomly selecting parameters in the hidden layer of the OS-ELM and its network output not stable enough, are solved by optimization. Finally, the effectiveness of the improved fault diagnosis model in improving the accuracy is verified by simulation experiments.
Coordinate Measurement Machines (CMMs) have been extensively used in inspecting mechanical parts with higher accuracy. In order to enhance the efficiency and precision of the measurement of aviation engine blades, a sampling method of profile measurement of aviation engine blade based on the firefly algorithm is researched. Then, by comparing with the equal arc-length sampling algorithm (EAS) and the equi-parametric sampling algorithm (EPS) in one simulation, the proposed sampling algorithm shows its better sampling quality than the other two algorithms. Finally, the effectiveness of the algorithm is verified by an experimental example of blade profile. Both simulated and experimental results show that the method proposed in this paper can ensure the measurement accuracy by measuring a smaller number of points.