Vickers hardness indentation size effect in selective laser melted MS1 maraging steel

© IMechE 2019. In this paper, selective laser melting fabricated specimens in non-heat-treated and heat-treated conditions were subjected to Vickers microhardness testing, by using a full range of loadings: 10, 25, 50, 100, 200, 300, 500, and 1000 g. Microhardness of longitudinal sections and cross-sections were correlated and the obtained values were plotted against loadings and indentation size effect was studied, in order to find the optimal loading range, that gives the material true microhardness, or load-independent hardness. The load dependence of the measured Vickers hardness values was described quantitatively through the application of the Meyer’s law, proportional specimen resistance, and the modified proportional specimen resistance model. It was found that the microhardness rises as the loading is higher, causing a reversed indentation size effect, clearly indicating the range of true hardnesses of the tested material. Also, proportional specimen resistance and modified proportional specimen resistance models were found to have the highest correlation factors indicating their higher adequacy compared to Meyer’s prediction model.The authors wish to acknowledge the support of European Commission through the project “Advanced design rules for optimal dynamic properties of additive manufacturing products – A_MADAM”, which has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 734455

A novel fully fast recovery EMG amplifier for the control of neural prosthesis

Ovaj članak predstavlja novo EMG (elektromiografsko) brzo oporavljivo pojačalo, koje se može koristiti kao sučelje za kontrolu neuronskih proteza. Osnova predloženog električnog kruga je standardno instrumentacijsko pojačalo implementirano pomoću tri operacijska pojačala s integratorom u negativnoj povratnoj petlji diferencijalnog pojačala. Standardno instrumentacijsko pojačalo s tri operacijska pojačala je modificirano uvođenjem analogne linije za kašnjenje između prvog stupnja (diferencijalni ulaz - diferencijalno izlazno pojačalo) i drugog stupnja (diferencijalno pojačalo). Glavna svrha analogne linije za kašnjenje je kašnjenje EMG signala i poticaj artefakta između prvog i drugog stupnja. Uvođenjem linije za kašnjenje u standardnom instrumentacijskom pojačalu s tri operacijska pojačala, pokazano je da se poticaj artefakta može otkriti prije nego što se pojavi na izlazu iz pojačala. Na taj način kontrolni sklopovi pojačala imaju dovoljno vremena da onemoguće integrator u diferencijalnom pojačalu, i spriječe nakupljanje naboja u kondenzatoru integratora. Također je pokazano da ova konfiguracija EMG pojačala ima ultra brzo vrijeme oporavka, tako da se može koristiti kao sučelje za kontrolu neuronskih proteza.This paper presents a novel EMG (electromyography) fast recovery amplifier, which can be used as a neural prosthesis control interface. The basis of the proposed circuit is standard three op-amp amplifier with integrator in the negative feed-back loop of the differential amplifier. The Standard three op-amp instrumentation amplifier has been modified by introducing analog delay line between the first stage (differential input - differential output amplifier) and the second stage (differential amplifier). The main purpose of the analog delay line is to delay EMG signal and the stimulus artifact between the first and the second stage. It is shown that by introducing a delay line in the standard three op-amp instrumentation amplifier, stimulus artifact can be detected before it appears at the output of the amplifier. Thus the control circuits of the amplifier have enough time to disable the integrator in the differential amplifier, and prevent charge accumulation in the integrators capacitor. It is also shown that this configuration of the EMG amplifier has ultrafast recovery time, so it can be used as a control interface of the neural prosthesis

Improvement of the maintenance management process of complex technical systems which demand high reliability

Glavni cilj ovog istraživanja bio je razviti postupak za ocjenjivanje izvedbe funkcija održavanja u organizacijama koje su odgovorne za održavanje sustava koji zahtijevaju visoku razinu pouzdanosti; postupak koji bi, uz manje izmjene, mogao biti primjenjiv i u drugim organizacijama. Proces uključuje razmatranje čimbenika koji utječu na uspješnost i učinkovitost funkcije održavanja. Istraživanje je provedeno u organizacijama koje se bave održavanjem zrakoplova, u regiji jugoistočne Europe.The main objective of this research was to develop a procedure for assessing the performance of maintenance functions in organizations that are responsible for maintaining systems that require a high level of reliability; a procedure which, with minor changes, could be applicable in other organizations, as well. The process included consideration of factors that affect the success and performance of maintenance functions. The research was carried out in Aviation Maintenance Organizations in the region of South-eastern Europe

The analysis of the impact on the safety of traffic participants and causing the accidents of working machines – tractors

U radu su analizirane prometne nezgode u kojima je jedan od sudionika traktor u razdoblju od jedanaest godina (2002. – 2012.) na teritoriji Srbije. Cilj rada je istraživanje posljedica, broja i vrsta uzroka kod ovog tipa nezgoda, kako bi se stvorile baze znanja neophodne za unapređenje konstrukcije i označavnje traktora s aspekta bezbjednosti. Analiza podataka provedena je na uzorku od n=13246 prometnih nezgoda u kojima je jedan sudionik traktor. Autori su koristili jednosmjernu analizu varijance (ANOVA) uključujući i post hoc test (Scheffe). Značaj studije je u preciznijem otkrivanju veza između posljedica, broja i vrste uzroka kod ovog tipa nezgoda uz naglašavanje potrebe za detaljnijim pristupom u prevenciji nezgoda.The paper analyses traffic accidents in which one of the participants were tractors, in the period of eleven years (2002 – 2012) on the territory of the Republic of Serbia. The aim of the research is the exploration of the consequences, number and type of causes of these type accidents, in order to create a knowledge base that is needed for the improvement of the construction and identification of tractors, from the aspect of safety. Data analysis was performed on the sample of n=13246 traffic accidents in which one of the participants was a tractor. The authors used one-way analysis of variance (ANOVA) including post hoc test (Scheffe). The significance of the study lies in the precise detection of the connection between the consequence and the number and types of causes in this aspect of accidents, while stressing the need for a more detailed approach in the prevention of accidents

Case Study of Healthcare Organization Improvement with Lean Concept

The goal of each company today is to improve business and increase profit through the reorganization and simplification of its processes, decrease of costs and resources utilization etc. Improving the business is usually implemented through different techniques and methodologies that have been developed. One of the ways to improve service processes, and health system processes also, is the implementation of the lean concept. This study shows benefits from using Lean tools value stream mapping (VSM) and simulations to simplify the laboratory work process. Using the VSM and simulation in department of clinical biochemistry authors showed significant improvement of the clinical processes such as eliminating non-value added times (NVAT) by minimum 30 working days/year, increasing number of laboratories analyses by approximately 80.000 analyses/year, eliminating unnecessary movement of 39,000 - 52,000 meters/year for samples and 78,000 - 104,000 meters/year for stuff and decreasing patient waiting times from average 70 to 20 min/patient

NETWORKS AND QUALITY IMPROVEMENT

Tools used in the past to analyze business value creation, such as value chain and process models, are simply too slow, inadequate, or inappropriate to address this new level of business complexity. In stead of that, company has to find way to create quality management system in a multi-layered supply chain. The problem can be solved by networking in the cluster. Cluster can be known as a competitive cooperation in the purpose to gain higher level of competitiveness and success. Bat there is another problem: Organization of the production process in a company is extremely complex process itself, and when we transfer it to the cluster level, we get a complex task which is difficult to solve. For that purpose, this paper analyses the conditions and possibilities that would enable those structures to adapt to changes in the surroundings - flexibility and management adequacy of production and organizational structures - by creating network value system

Project Management Maturity and Business Excellence in the Context of Industry 4.0

Even though Industry 4.0 is primarily focused on the implementation of advanced digital technologies, this is not the only aspect that should be considered. One of the aspects that calls for attention is the ability to create a sustainable and agile industrial environment. In this sense, the role of project management is crucial for achieving business excellence in a new industrial paradigm. The main goal of this paper was to determine the impact of different levels of project management maturity on business excellence in the context of Industry 4.0. The research in the paper was made using a sample of 124 organizations, differing in industry type and size, and recognized through the business excellence awards or recognitions given by European Foundation for Quality Management (EFQM). Using the Project Management Maturity Model (ProMMM), a significant connection was found between project management maturity and business excellence. Considering technology advances, these relationships were further examined in the context of Industry 4.0. Empirically based conclusions were drawn, which contribute to the literature on project management and business excellence in the context of Industry 4.0. Practitioners can implement them for more effective project management with the intention of bringing excellence into the organization’s operations and results. Additionally, they can be useful to help organizations better cope with changing technology trends

Model risk identification in project of land consolidation

Project of land consolidation are very complex and demanding ventures. Given that and the fact that there are a large number of stakeholders, it is clear that the projects load a large number of risks that affect the realization of the land consolidation projects. This work treats study cases of completed projects on territory in the Republic of Serbia, which are the basis to identify risks which affect the realization of land consolidation projects. Right this way in model being developed, will incorporate past experience and thus reducing the effect of adverse events during realization of the land consolidation projects. Results obtained in this study, the implementation can be found, not only in the Republic of Serbia, but also in other countries where the land of consolidation are in expansion

Application of group technology in complex cluster type organizational systems

The aim of this research was to contribute to the development of structural design procedures of complex - cluster type organizational systems. Industrial clusters can help companies to improve their own market positions, effectiveness, productivity and product quality. Organization of the production process in a company is an extremely complex process itself, and when it is transferred to the cluster level, the result is a complex task which is difficult to solve. For that purpose, this paper analyses the conditions and possibilities that would enable those structures to adapt to changes in the surroundings - flexibility and management adequacy of production and organizational structures - by lowering the degree of complexity. For the time being, no simple models which would enable an increase of process effectiveness in complex organizational units like clusters have been developed. One of the possible solutions which would decrease the complexity of flows and increase process effectiveness within an industrial cluster is the application of Group approach

ANALYSIS OF THE POSSIBILITY FOR ESTABLISHING PROJECT MANAGEMENT OFFICE (PMO) IN COMPANIES IN SERBIA

Project Management Office (PMO) is an organizational unit established to help project managers, project teams and the various levels of management in carrying out the principles of project management. The research was carried out in Serbia, in 2011, with the aim to establish which methodologies and techniques are used for project m anagement, and which of them are used the most frequently. Furthermore, the need for establishment of PMOs in Serbia is discussed. These offices should help in establishing a standardized methodology (at the organization level) and thus overcome the obviou s poor use of any project management methodology at all