186,413 research outputs found
Mechanical Characterisation of Metal/Polymeric Composite Waste/Metal Sandwich Panel
No full textThe aim of the paper is to compare a tensile strength and an elongation at break of the sandwich materials with different cores created with the polymeric composite mixture at simultaneous acting of the cyclic degradation. The sheet S235J0 is the face. The core of the sandwich panel is from the structural two-component adhesive, from the composite material based on the microparticles of the glass-bead, the rubber and the textile microfibre waste from the tyre recyclation and the rubber particle waste from the tyre recyclation. Namely the secondary raw materials based on the textile microfibres are difficult to utilize in another processing. This research showed one of prospective possibilities of the material utilization of this secondary raw material. The highest tensile strength of the sandwich materials is reached with the core from the composite material on the glass-bead base. The significant fall of the tensile strength of the sandwich materials was measured at the material with the core based on the rubber and textile microfibre waste from the tyre recyclation. The elongation at break was not almost changed. The core crackled at lower loading at first. The face tolerated higher loading
Dynamic Analysis of a 3D Printer Based on the Delta Mechanism
No full textThis work presents the computational modeling and dynamic analysis of a three dimensional printer based on a delta mechanism using the multidisciplinary open source software MBDyn. Three dimensional printers can make complex parts with a minimum waste of material. These printers are usually slower than conventional methods of fabrication like milling. To overcome this problem, different types of mechanism such as Delta and SCARA have been tested in open source 3D printers. They are faster and have less components than cartesian mechanisms, but they demand a inverse kinematic analysis to translate G-code to printer motion. The printing process requires several steps from the computer modeling of the part to the 3d printing. A set of Python scripts and MBDyn analyses were used to mimic this process and to provide the dynamic behavior of the complete model of the printer. To understand the impact of the flexibility of the parallel arms in the printing process, three materials were tested: ABS plastic, aluminum and steel. Besides the arm's material, another element that influences the printer performance is the stepper motor, thus different microstepping strategies were simulated. The dynamic analysis showed that the flexibility of the parallel arms plays an important role in the positioning error of the deposition head. Plastic arms are cheap and easy to build, however, their deformation is excessive in high speed displacements. The microstepping analysis revealed that the ratio between carriage displacement and motor step is more important than the microstepping strategy
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Effect of Fiber Orientation on Tribological Performance of Abaca Fiber Reinforced Epoxy Composite Under Dry Contact Conditions
No full textAbstract: Today, natural fibers and their composites are increasingly present in the industrial production of various materials, ranging from the textile industry, through construction, all the way to the automotive and aerospace industry. Their wide application is justified by the replacement capabilities of composite materials reinforced with synthetic fibers. This paper presents tribological research of abaca fiber reinforced epoxy composite material. Fiber orientation and its effect on the tribological performances of the composite was analyzed. The extremely low viscosity epoxy resin reinforced with NaOH treated long abaca fibers is investigated under the different operating conditions. The unidirectional abaca fibers reinforced the epoxy resin and formed composite specimens with fibers in three directions, Parallel (P-O), Anti-Parallel (AP-O), and Normal (N-O), respecting the sliding direction. The specimens were fabricated by fiber volume fraction of 30 wt% using the vacuum infusion technique. The block- on-disc (BOD) apparatus was employed to exhibit the tribological tests. To conduct the test, a normal load of 35N and 45N was applied. The experimental results showed that the presence of abaca fiber significantly improved the wear characteristics of the matrix than the neat epoxy. An increased coefficient of friction was observed in samples with anti-parallel oriented fibers at an
applied load of 35N. The conducted research showed that the use of abaca fibers as fillers could improve the tribological characteristics of the epoxy resin-based composite material
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Global Chassis Control: Integration Synergy of Brake and Suspension Control for Active Safety
No full textThe paper deals with the investigation of integration synergy of brake and suspension control for reduction of the stopping distance. The basic idea is to take a controllable suspension and to optimize it for decrease of road-tyre force fluctuation. A nonlinear suspension control is proposed for this task. The outlined concept is implemented in a multibody simulation environment and simulation experiments verify its contribution
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Integrated environmental risk assessment of major accidents in the transport of hazardous substances
No full textAt present, the environmental risk assessment of major accidents is mainly carried out for stationary risk sources. Only marginal attention is paid to mobile risk sources, while the currently available methodologies require a relevant expertise and time for their application, which is only partially possible in most scenarios. In the present study, an integrated approach to environmental risk assessment in the transport of hazardous substances (iTRANSRISK) was developed. The approach proposed is based on the principle of index-based assessment of leakage scenarios involving toxic and flammable substances during transport, in the context of indexing environmental vulnerability. The key point of the method is the conversion of local-specific data concerning the risk potential of the transported substance, the consequences and the probability of a major accident, and environmental vulnerability assessment into a single entity. The created integral approach is proposed for the needs of carriers of the hazardous substances and the state administration bodies. The proposed approach is determined for the screening risk assessment at the beginning of the process of the planning a suitable transport routes and the results are for information only. An example of the application of the iTRANSRISK integrated approach is demonstrated considering an explosion scenario following a propane tanker leak (18 t) in a forested area, with moderately susceptible soils and no surface water or groundwater affected
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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