Papers by Cristian Doicin
Proceedings of the ... International Conference on Business Excellence, Jul 1, 2023
The scientific paper aims to present the performance evaluation methods in ports and port organiz... more The scientific paper aims to present the performance evaluation methods in ports and port organizations and the contributions that an integrated quality management system can bring. Water transport is the most reliable mode of transport, both in terms of transport capacity and in terms of consumption and environmental aspects, compared to other modes of transport. But it cannot function at an optimal level without complex and permanent onshore management. The port organizations have an important contribution in the global performance of the port and thus in the economy of a country that is open to the sea. By approaching an integrated quality management system, port organizations can achieve the expected performance in a planned and systemic way in terms of quality, environment, logistics supply chain security, etc. The paper analyzes the performance assess in ports and port organizations, the most common applied regulations and management systems in port organizations and the advantages an integrated quality management system brings in increasing organizational performance by preventing losses and improving processes using known methodologies globally promoted such as Lean. It also highlights the relationship of mutual dependence that the port performance and the port organizations performance have on each other.
IOP conference series, Nov 1, 2022
Mathematics
This paper examines the movement of waves that occur in a fuel tank—both with and without a wave ... more This paper examines the movement of waves that occur in a fuel tank—both with and without a wave breaker—when a car is travelling at a constant speed and then suddenly brakes. This phenomenon is known as slosh noise, and the paper presents an analysis of the movement of free surfaces in relation to the level of noise generated. The paper focuses on mathematical models of the fluid flow for both tanks—one without any technical solutions for breaking waves, and the other with a solution for breaking waves. The model is constructed based on a set of initial hypotheses about the fluid flow within the tank, by developing the speed potential in a series of fundamental solutions and considering the main variables that affect the phenomenon of sloshing, such as the depth of the liquid, the tank’s geometry, and the frequency and amplitude of the initial external force acting on the tank. The analysis of free surface movement is used to find the correlation with the sound generated in the tan...
IOP Conference Series: Materials Science and Engineering, 2016
The paper presents a product design making of, over a "delicate issue" in automotive industry as ... more The paper presents a product design making of, over a "delicate issue" in automotive industry as slosh noise phenomena. Even though the current market tendency shows great achievements over this occurrence, in this study, the main idea is to design concepts of slosh noise baffles adapted for serial life existing fuel tanks in the automotive industry. Moreover, starting with internal and external research, going further through reversed engineering and applying own baffle technical solutions from conceptual sketches to 3D design, the paper shows the technical solutions identified as an alternative to a new development of fuel tank. Based on personal and academic experience there were identified several problematics and the possible answers based on functional analysis, in order to avoid blocking points. The idea of developing baffles adapted to already existent fuel tanks leaded to equivalent solutions analyzed from functional point of view. Once this stage is finished, a methodology will be used so as to choose the optimum solution so as to get the functional design.
Journal of Materials Processing Technology, Oct 1, 2003
Experiments were carried out for statistic modelling of machine tool efficiency and of specific c... more Experiments were carried out for statistic modelling of machine tool efficiency and of specific consumed energy in machining. The machine tool efficiency, specific consumed energy and consumed energy have been determined as functions of different machining parameters. For establishing the relationship between the above parameters, the experimental data were statistically modelled using the Response Surface Methodology. The experimental data were obtained by measuring the working parameters of machine tool and the power consumed by the electric motor, for every experience of the experimental program. These data were used in estimation of the coefficients of the models and in their statistic analysis. As an example, the models of efficiency for a vertical-milling machine and of specific consumed energy for milling of an aluminium alloy on this vertical-milling machine are described, ones illustrated.
The current research presents quantitative data and communication network design analysis for an ... more The current research presents quantitative data and communication network design analysis for an international multimodal transportation company. The proposed communication network is considered as a hierarchical organization from the additive manufacturing sector. The authors define the main management levels, the information transfer nodes and the direction of data displacement and design the general structure of the network using oriented graphs. For the quantitative analysis, centrality evaluation indicators are used. It is concluded that the degree of proximity decreased proportionally with the number of nodes between any two members of the communication network.
MATEC Web of Conferences, 2019
Additive manufacturing is a worldwide trend and has been successfully adopted in a wide variety o... more Additive manufacturing is a worldwide trend and has been successfully adopted in a wide variety of domains. With applications ranging from automotive, aerospace, military, consumer goods bioprinting and even wearable electronics, the need for trained workforce in additive manufacturing is in high demand. Academia all around the world is adapting to this new trend trying to develop new strategies in delivering suitable competences to their undergraduate, masters’ and PhD students. Such an initiative is the Erasmus+ project TecHUB 4.0 which brings together four complementary universities from Romania, United Kingdom and Poland. The main goal of the project is to bring together professors, industry specialists, researchers, managers, and entrepreneurs to deliver, using methods based on modern teaching technologies, especially on the use of web-based platforms and digital technologies – e-learning and interactive platforms, their knowledge to the young students wishing to become entrepr...
MATEC Web of Conferences, 2021
Integration of additive manufacturing throughout a product’s lifecycle has proven over the years ... more Integration of additive manufacturing throughout a product’s lifecycle has proven over the years to bring substantial competitive advantages to companies worldwide. Complex geometries, quick iteration and lead-time reduction are universally seen as the biggest benefits of 3D printing. North American users also cite cost savings as a major benefit. More than half of the technologies’ applications are related to prototype manufacturing, especially due to high-cost savings in the development phase. Complex prototypes often require a cross reference when it comes to the design rules which need to be considered during the development stage. Thus, this study aims to analyze the various parameters when designing and manufacturing a complex prototype using material extrusion. Some of the main issues covered are related to analyzing the interference between components, adjusting the dimensions of the component elements according to the material contractions, the amount of used material and t...
International Journal of Rapid Manufacturing
Revista de Chimie
Cranioplasty is a surgical procedure used to repair cranial defects left behind after injury or p... more Cranioplasty is a surgical procedure used to repair cranial defects left behind after injury or previous surgeries. Postoperative results of cranioplasty have been drastically improved with the usage of custom made cranial implants, which can replicate the missing bone almost identical in shape. Materials used for these custom implants vary depending on the used technology. Additive manufactured implants are generally made with metal alloys powders. The present research conducts a Finite Element Analysis study in regard to modification of intracranial pressure conditions, in normal range between 7 mm Hg to 15 mm Hg, in four impact stress scenarios of fixed custom cranial implants. Two new cranial implant concepts are proposed by the authors, one with a sliding system and one with osteointegrating structures. Stress scenarios aim at evaluating implant behaviour in critical conditions such as a person falling from a certain height or an object being dropped, generating an impact point...
In this study, conventional and nanostructured yttria-stabilized zirconia (YSZ) thermal barrier c... more In this study, conventional and nanostructured yttria-stabilized zirconia (YSZ) thermal barrier coatings (TBCs) were deposited by atmospheric plasma spraying (APS) on Ni superalloy with NiCrAlY as bond coat. The TBCs were exposed to isothermal oxidation tests in an electric furnace under air at 1100 ̊C for 100, 200, 300, 400 and 600 hours and were investigated in terms of microstructure and microcomposition by using the scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS). The nanostructured YSZ coatings showed a better performance at isothermal oxidation tests, in particular in terms of thickness of thermally grown oxide (TGO) layer which had a parabolic growth behavior.
New polymeric blends were prepared by mixing some receipts of polyvinyl chloride (PVC) for medica... more New polymeric blends were prepared by mixing some receipts of polyvinyl chloride (PVC) for medical use with natural polymers (hydrolyzed collagen and a hydrolyzed collagen/elastin mixture), without the use of intercoupling agents. The mixtures were processed through rolling-pressing and extrusion. The new materials have physical and mechanical properties that allow their processing by using classical methods, specific for synthetic polymers. In vitro biocompatibility studies were performed on a primary culture of human dermal fibroblasts by the MTT test. The biocompatibility of the materials was tested in vitro by determining cell viability in a culture of human dermal fibroblasts by using the MTT method. The physical and mechanical properties and also the biocompatibility properties of the new materials recommend them to be used in the manufacture of medical devices.
Metalurgija, 2016
D. I. Băilă, C. V. Doicin, C. M. Cotruț, M. E. Ulmeanu, I. G. Ghionea, C. I. Tarbă, University Po... more D. I. Băilă, C. V. Doicin, C. M. Cotruț, M. E. Ulmeanu, I. G. Ghionea, C. I. Tarbă, University Politehnica of Bucharest, Bucharest, Romania In this paper, two prototypes of dental elevator was made by DMLS process, using a super alloy powder of Co Cr (ST2724G), with Phenix Systems machine, type PXS & PXM Dental, one with a threaded tail and another with a cylindrical tail. The quality obtained for the elevator is better, thanks to the material used and to the manufacturing process. For the elevator prototypes there were performed some Finite element method (FEM) analysis to identify stress locations and displacements. It was realized corrosion test in artificial saliva Fusayama Meyer (pH 5,5) at temperature of 37 ± 1 °C for 24 hours and remarks the importance of post treatment after DMLS process to obtain a better corrosion resistance in vitro.
Brand management is vital for identity development of any educational entity. The paper proposes ... more Brand management is vital for identity development of any educational entity. The paper proposes a brand management strategy developed for a large university using several additive manufacturing applications. A product design and development team identified the need for brand establishment through identity promotion of the universities’ unique capabilities. Several concepts were generated and analysed in accordance with product requirements and restrictions. After technology selection, the selected product was a key chain manufactured with Fused Deposition Modelling. To expand the product portfolio and thus the range of proactive actions within the branding process, two more products were selected for manufacture. Open cast epoxy resin medals and open cast chocolate candies required the development of specialised RTV silicone moulds. Branding management was done in strict correlation with the developed products. Various proactive, reactive and mixed actions were developed and implem...
The variants of process plan are difficult to obtain. In a computer aided environment there are t... more The variants of process plan are difficult to obtain. In a computer aided environment there are two main possible alternatives to do that: Variant Process Planning and Generative Process Planning. First alternative is based on large databases storing the process plan variants for different groups of parts, developed in a previous stage. The second alternative, more difficult to design, define and develop, but much more flexible, is based on a method of defining the variants of process plan, in a generative way. In such a system, the input data are the assembly of geometrical information extracted from the solid model of the part, made with an integrated or external CAD system. Within the technological module, blocks with certain functionalities identify the groups of data assigned to the features, which define the external and internal shape of the part. The identified features are subsequently analysed, ordered and grouped so as to form complex features. Then, the combinations of c...
he medical industry has greatly benefited from the aid of various additive manufacturing (AM) tec... more he medical industry has greatly benefited from the aid of various additive manufacturing (AM) technologies, especially for applications that include the fabrication of bespoke implants and guides, devices and surgical instruments. Manufacturing functional prototypes that can behave as close as possible to the final product is a key factor in developing successful anatomically compliant medical products. The current research is intended to evaluate the optimum AM technology to fabricate medical prototypes with thin wall structures, destined for anatomical functional tests and surgical practitioner feedback. The main criteria of evaluation were: speed of fabrication from *.STL file to final prototype, mechanical characteristics and manufacturing costs.
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Papers by Cristian Doicin