1,721,037 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Behaviour of Loaded RC Columns Encased With Polymer Modified Ferrocement Under Concentric Loading
No full textConcrete structures are the pivot of civil engineering due to its extensive use; they provide excellent performance in terms of structural behavior and durability. The zones which are exposed to severe mechanical and environmental loading require rehabilitation. Rehabilitation is provided to the structures which are deteriorated and to those elements whose load carrying capacity is decreased due to cracks. Rehabilitation of deteriorated concrete structures leads to significant user costs and is also a heavy burden from the scocio- economic viewpoint. As a consequence, Rehabilitation of structures must be developed.
The rehabilitation and strengthening of pre-existing reinforced concrete columns using wire mesh jacketing is done based on a well-established fact that due to application of jacketing lateral confinement of concrete is decreased and its axial compressive strength can sustainably increase. In recent years, various methods of external confinement of concrete are being used such as jacketing using Steel Angle, FRP, Bracing Infill walls, Ferrocement has emerged as a popular method of column retrofit. Retrofitting of element reduces the damage of an existing structure during a future earthquake. The basic aim is to strengthen a structure in accordance to the requirements of the current codes for seismic design. Therefore, rehabilitation of deficient columns is required to increase load carrying capacity and decrease the lateral deflection of column due to buckling. External confinement of the damaged column can be done by different materials such as Ferrocement and Polymer. Ferrocement confinement for re- strengthening of deteriorated columns is one of the oldest, efficient and cost effective techniques. Polymer induced Ferrocement is a form of thin wall reinforced concrete using wire mesh and high strength mortar mixed with polymer. The wires used as reinforcement in wire mesh provide a higher specific surface hence providing strength to the ferrocement.
Considering all these points, the present study focused on the behavior of RCC columns with different slenderness ratios on the Polymer induced Ferrocement confined. In the experimental part of this thesis, column specimens with three different slenderness ratios (λ) were casted. Three slenderness ratios were considered λ =3, λ =6, λ =12.
These specimens were further divided in to three categories. The first category was of control samples consisted of no Loading and no Ferrocement columns from each size group, second category consisted of normal samples and pre-loaded samples confined with Polymer (SBR) Ferrocement using one layer of wire mesh and third category consisted of normal samples and pre-loaded samples confined with Polymer (SBR) Ferrocement using two layers of wire mesh. In second and third category the 80% loading was done with respect to the peak load of control samples and the polymer used was SBR. All the columns were tested under monotonic uni-axial compression loading. As the slenderness ratio increased from λ =3, λ =6 to λ =12 the load carrying capacity decreased from 180kN , 154kN to 132kN, there was different trend while increasing the number of mesh as the load carrying capacity increased 53.1% to 70 % in λ =3 and the similar trend was seen in λ =12, increased from 39.8% to 51.2%
Retrofitting of RC Beams Using Ultra High Performance Fiber Reinforced Concrete
No full textReinforced concrete structural components are found to exhibit distress, even before their service period is over due to several causes. Such unserviceable structures require immediate attention, enquiry into the cause of distress and suitable remedial measures, so as to bring the structures back to their functional use again.
This strengthening and enhancement of the performance of such deficient structural elements in a structure or a structure as a whole is referred to as retrofitting. The all important issue to be addressed in retrofitting is life safety .What can be done to prevent collapse of the structure and prevent injury or death to occupants? Some retrofit requirements may try to address only the issue of life safety, while acknowledging that some structural damage may occur.
Structures that are deficient in shear can be strengthened or repaired by using various methods, e.g., external pre-stressing, shortcreting, polymer impregnation, steel plate bonding, fiber reinforced polymers (FRPs) and other cementitious materials including ultra high performance fiber reinforced concrete (UHPFRC).
To overcome all the above problems faced in different retrofitting techniques, a new cementitious material with ultra high performance characteristics like very high compressive strength (above 110 MPa), high tensile strength due to addition of fibers, high flexural strength, very less permeable and high workability i.e. UHPFRC came into existance. UHPFRC with its remarkable characteristics as a repair material for concrete structures in harsh environmental conditions and high loads works excellent.
In the present thesis shear deficient RC beams initially stressed to a prefixed percentage i.e. 60% of the failure load are retrofitted using UHPFRC. Retrofitting is done using three different techniques i.e. Side face retrofitting, U-Type retrofitting and External 25 mm thick jacketing.
From the study it is seen that the ultimate load carrying capacity of RC beams retrofitted with UHPFRC is significantly increased with Side face and U-type retrofitting. Moreover, this technique also increased the ductility and energy absorption of RC beams which resulted in the usefulness of UHPFRC as a retrofitted material. A comprehensive literature review is carried out for better understanding of UHPFRC as a retrofitting material compiled from many references representing research, development, and deployment efforts around the world, this thesis report provides a framework for gaining a deeper understanding of UHPFRC as a retrofitting material
Effect of prestress level on beams retrofitted with prestressed frp sheets
No full textME, CEDThe Retrofitting is a technique of strengthening the existing structures which are unable to take the unpredicted loads and deteriorated due to environmental effect. This technique has been effectively applied on the existing structures like buildings, dams, bridges etc. There is a various existing techniques of retrofitting which are section enlargement (jacketing), bonded steel plates, strengthening with FRP composite sheets. A lot of research has been carried out for above retrofitting techniques. From all the above techniques, FRP is the most effectively used for the retrofitting. The advantages of resistance to corrosion and higher specific strength make this material ideal for reinforcing existing structures.
For retrofitting the existing structures, FRP can be used by various techniques such as FRP laminates, FRP non prestressed sheets, FRP prestressed sheets, FRP wrapping and FRP reinforcement also. The amount of research conducted on retrofitting by prestressed FRP sheet is quite less. So in this thesis, the effect of different prestresse levels of FRP sheets on beams have been carried out
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Mechanical Properties Of Polymer Modified Ferrocement
No full textME, CEDIn an effort to improve the performance of mortar, polymer is introduced into mortar. It has been reported that polymer-modified mortar (PMM) is more durable than conventional mortar due to higher strength. This research was carried out to establish the effects of polymer addition on compressive strength, flexural strength, modulus of elasticity of mortar and flexural strength and tensile strength values on polymer modified ferrocement samples with mortar of constant flow value. Two types of polymers were used i.e SBR and VAE polymer. The mixes were prepared with polymer-cement ratio of 0% , 5%, 10%, 15% and 20% for each and a flow value of 110 +_ 5 is fixed for every mix of mortar.
The addition of polymer in the mortar results in reduction of w/c ratio for the mixes with constant flow value while mixes with same w/c ratio result in increase in flow value. The results indicated that the compressive strength of polymer modified mortar is lower than the unmodified mortar for constant w/c ratio after 7 and 28 days of wet curing days. The compressive strength of SBR polymer modified mortar increases but of VAE modified mortar decreases after 7 and 28 days at varied w/c ratio. The flexure strength increases for both mixes of the varried w/c ratio at the same flow value. The main aim of polymer addition is to increase the flexure or bending stress of conventional mortar. The modulus of elasticity of conventional mortar is higher than that of polymer modified mortar and the failure of conventional mortar was found more brittle and less deflection value as compared to the polymer modified mortar.
The flexure strength of ferrocement samples also increases on polymer addition for third point loading test.
Polymer modification of cement paste increases its tensile and flexural strength and reduces its brittle nature. We will conclude by showing that future use of polymer modified cement composites will likely be in the area of durability and performance improvements of cement materials applied in thin sections.Thapar University, Patial
Retrofitting of Beam Column Joints Using Confined High Performance Hybrid Fiber Reinforced Concrete
No full textPresently, various multi storey buildings are serving to the societies which were constructed before the implementation of seismic codal guidelines. The change in occupancies of building, amendment in codal provisions and to meet the present seismic demand, there is an urgent need for up-gradation of these structures. In the past, various methods, such as steel plate adhesion, jacketing, and fiber reinforced polymer (FRPs), have been successfully deployed to retrofit the pre-seismically detailed structures. Nonetheless, the demerits associated with these techniques depict the limitation in the performance of the retrofitted BCJ. The initial damage level also significantly governs the retrofitting strategies and affects the performance of the retrofitted BCJ.
The newly developed high performance hybrid fiber reinforced concrete (HP-HFRC) revealed excellent properties (post-elastic ductility, strain hardening, higher tensile strain, higher bond strength and durability) which are expected from the retrofitting materials. Hence, it can be used as a new retrofitting material. Moreover, in past studies, much attention was not paid to the fact that what is the initial damage level of the beam-column joint before the time of retrofitting. Therefore, the present study explores the possibility of using HP-HFRC in the retrofitting of beam column joint which is initially damaged to different damage levels. In the study firstly, the HP-HFRC is developed using trial and error method and fresh, mechanical and durability properties were evaluated. Thereafter, the design mix is refined using Andreasen and Andersen (A&A) packing model. The fresh, mechanical, durability and microstructural properties are evaluated after 28 days of curing and are further used for retrofitting the initially damaged beam column joint.
In the second phase of the study, sixteen beam column joint specimens are cast and set of two specimens are tested as control specimens for each retrofitting strategy. The complete load displacement hysteresis behaviour of control specimens subjected to quasi-static reversed cyclic loading is recoded. Based on the obtained load displacement hysteresis of control specimen, the different damage levels viz., slight, moderate, severe and complete have been calculated using Park and Ang model. Further beam column joints have been initially damaged to achieve the above mentioned damage levels. Thereafter, the initially damaged specimens have been retrofitted using HP-HFRC and wire mesh confined HP-HFRC and tested under cyclic loading. The performance of retrofitted beam column joints has been measured in terms of load displacement behaviour, ultimate lateral drift capacity
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displacement ductility, energy dissipation, stiffness, strength degradation, and principal tensile stress.
The proposed retrofitting strategies significantly affect the performance of the initially damaged beam column joint. An improvement of 14.28% and 28.57%, in ultimate drift ratio (UDR), as compared to control specimens has been observed after retrofitting with HP-HFRC and wire mesh confined HP-HFRC beam column joint, respectively. The ductility of HP-HFRC retrofitted beam column joint and wire mesh confined HP-HFRC depicts the maximum improvement of 45.29% and 63.23% respectively than control specimen. The energy dissipation capacity of HP-HFRC confined and wire mesh confined HP-HFRC retrofitted specimen is 8894 kN-mm and 11827.67 kN-mm, respectively. The maximum improvement in energy dissipation in wire mesh confined retrofitted specimen exhibited the 1.32 times improvement over the HP-HFRC confined retrofitted specimen. The maximum improvement in stiffness and strength retention has been observed in wire mesh confined retrofitted specimen than HP-HFRC retrofitted specimen. The excellent improvement in principal tensile resistance capacity along with lower rate of post elastic principal tensile resistance degradation is observed in wire mesh confined HP-HFRC.
The effect of initial damage level on the performance of HP-HFRC and wire mesh confined HP-HFRC retrofitted specimen is also evaluated. It has been found that the ultimate drift capacity (UDC) of confined HP-HFRC retrofitted initially complete damaged specimen decreased up to 28.57% and at the same initial damage level, wire mesh confined HP-HFRC retrofitted specimen regains the original drift capacity. Also, the increment in initial damage level decreases the ductility or vice versa. The slope of stiffness and strength degradation is decreased as the initial damage level shifting from complete to slight damage level which reflects the improvement in post elastic behaviour. The maximum improvement in energy dissipation has been found in initially slight damage specimen in both types of retrofitting strategy. Therefore, it is concluded that retrofitting of beam column joint using HP-HFRC and wire mesh confined HP-HFRC improves the overall performance of the beam column joint. However, the behaviour of BCJ retrofitted with wire mesh confined HP-HFRC is superior to HP-HRFC retrofitted joints, due to confinement provided by wire mesh. Further, the initial damage level significantly affects the performance of the retrofitted beam column joint. The performance of the retrofitted specimen improves as the damage level shifts from complete to slight
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