bluuebunny/crossref_metadata_2025 huggingface dataset:
The Measurement Method of Distance from Vehicle Ahead Based on Infrared Technology
Authors: Zhang Nan
Published: September 2014

In this paper, the infrared signal is collected through the Cassegrain optical system, and then before exhaust thermistor detector is collected infrared signal into a voltage signal in the converted voltage signal corresponding processing, such as signal amplification, filtering and demodulation processing, the processed signal and system parameters in real-time control of the comparisons of the relative distance of the vehicle in front, followed by the MCU through the vehicle in front distance value judgments and to follow up the speed of vehicles, in order to achieve the use of infrared technology to detect the distance of the vehicle in front, and unmanned exploration technology focal car fleet .
Research on Optimal Control Model for Ball Mill Based on Genetic Algorithm
Authors: Zhang Cheng Liang , Yang Jia Fang , Cao Yong Hua
Published: September 2014

As the key equipment in coal-fired power plants, the optimal control problem of ball mill is an important factor affecting the efficient operation of the mill. In this paper, the output model, energy consumption model and unit consumption model of coal pulverizing system are built on the basis of analysis of ball mill running condition. The unit consumption model is used as the genetic algorithm fitness function. The outlet temperature, practical ventilation and coal load of ball mill are chosen as the optimization variables. The algorithm model is built to solve the multi-objective problem of ball mill.
Atrium Fire-Proof Design in Ecological Strategy Taking the Library of Shandong Jiaotong University as an Example
Authors: Yin Jing
Published: September 2014

In China the development pace of green building is becoming more and more fast. But there are many technical problems during the green building construction. The Library of Shandong Jiaotong University is the first case of green library building in China. The ecological implementation in the atrium is one of the important ecological strategies of the Library. While construction we encountered more technical problems, especially the contradiction between the natural ventilation, natural lighting and fire safety. In this article based on the atrium technology design of the green building and combined the practice of the atrium some strategies realizing natural lighting, natural ventilation in the fire safety, applicable, economy and art.are summarized in detail. It is the aim to give some references and to promote the green building implementation.
Analysis on the Influencing Factors of Grain Farmers’ Income in Heilongjiang Reclamation
Authors: Zhang De Hua
Published: September 2014

The grain farmers in Heilongjiang have made significant contributions to national food security, but they always have been plagued by the lower income. Based on the survey data of reclamation’s grain farmers, the paper selects the multiple linear regression models and uses stepwise to analyze the influencing factors of grain farmers’ income in Heilongjiang reclamation. The results show that total sown areas, proportion of the plain areas, total cost of input, annual labor work days, highest education in family and cadre relatives are the main influencing factors of grain farmers’ income in Heilongjiang reclamation.
Analysis of the Cool Bending Fracture of HRB400
Authors: She Yuan , Kong Wei Ming , Zhang Zhao Hui
Published: September 2014

The tests were conducted on 400MPa hot-rolled ribbed bar (HRB400). The cool bending fracture appeared frequently in the production was analyzed. The research result showed that the cool bending fracture of rebar were caused by element segregation of C, Mn, inclusions, the existence of banded structure, widmannstatten structure and bainite structure in the center and edge of rebar. The inclusions are the root cause of internal crack and one of the reasons to fracture. Reasonable cooling rate can refine grain size, while the overquick cooling speed could result in the formation of widmannstatten structure in acicular or plume, increased the brittleness of steel and reduce its cold bending properties. On this basis, some improvement opinions were put forward: using the raw material with low Mn, S and P; reducing the S content with pretreatment of hot metal; controlling the content of C and Mn respectively in C: 0.18 ~ 0.23%, Mn:1.20~1.30%; extending argon blowing time at argon flushing station, using electromagnetic stirring technology; controlling the cooling rate at 15 °C/s.
Study on Data Analysis System of Multi-Information in Arc Welding
Authors: Wang Jun Hong , Du Chang , Ling Li Gong
Published: September 2014

Welding used as a material connecting technology is widely applied in the manufacture and plays an important role. At present the rapid development of our country's manufacture results in the requirements of higher and higher welding quality. The advanced data analysis system was used in the welding process, to obtain parameters which were able to reflect the characteristics of welding process. On that basis, the parameters of welding process can be optimized and then offer help to improve the welding quality. The data analysis systems designed in this paper can be used in analyzing electrical signals, high-speed camera images and spectral data in the welding. This data analysis system provided a wide range of functions, such as: mapping of voltage and current waveforms, U-I curve, probability density curves of voltage and current, voltage and current filtering, calculation of short-circuit frequency, short-cycle variance and shot droplet transfer cycle variance, the importation of energy and integral of the spectrum intensity, analyzing the relevance of the electrical signals, playing multi-information of arc synchronously. In the experiment of pulsed MAG welding and laser-pulse MAG welding, the system was used in comparing the multi-information of the arc and its function was absolutely embodied.
Discussion for the Calculation of Carbon Content and Heating Temperature in Austenitizing of Cast Iron
Authors: Gong Wen Bang , Zhang Yun , Liu Huan , Wang Hua Fang , Wu Yu Qin , Sun Li
Published: September 2014

In this paper, a formula for calculation of carbon content during austenitizing of cast iron was developed with consideration of the effect of silicon content. According to this formula, carbon content of austenite at a certain austenization temperature for a cast iron with given composition can be easily calculated, and the austenization temperature for getting the expected carbon content in the austenite can also be determined. Besides, according to the relationship between austenization temperature Tx and the according carbon content Cax, and considering the effect of silicon content, the diagram of Cax, Tx and silicon content during the austenitizing process of cast iron was made.
DEFORM-Based Analysis and Discussion of Early Failure in Warm Extrusion Dies
Authors: Zhang An Min
Published: September 2014

In this study, the true working conditions of a warm extrusion die was simulated using DEFORM-3D software; images of the die’s temperature, stress, and wear distributions were obtained, the amount of wear of the die cavity were calculated, and the wear depth curves were drawn for each test point on the basis of this simulation. A production analysis along with the simulation revealed the main forms of early failure for the warm extrusion mold to be cracking failure, collapsing failure, and wear failure. Through data analysis, the areas of the die that cracked easily or showed heavy wear were identified. The steps required to prevent early failure are proposed in this article.
Research on the Synthesis and Characterization of a Novel Dendritic Thickening Agent
Authors: Wang Chao , Ouyang Jian , Zhu Zhuo Yan , Duan Gui Fu , Wang Feng , Wang Yuan Yuan
Published: September 2014

A novel dendritic thickening agent has been prepared on account of the poor temperature resistance performance and other shortcomings of conventional polymer thickening agent (HPAM), and has evaluated its monomer proportioning and the performance of formed fracturing fluid. Accordingly, it has derived that, when the concentration of the polar monomer AMPS and the functional monomer GL is 30% and 1%, respectively, this novel dendritic thickening agent is able to maintain the excellent temperature resistance and shear resistance of the fracturing fluid system at lower concentrations. The optimal formula of the formed fracturing fluid is: 0.4% thickening agent +0.15% pH adjusting agent +0.25% crosslinking agent +0.1% discharge aiding agent. Under the conditions of 170s-1and 150°C, it has tested its temperature resistance and shear resistance properties, and the final viscosity after shearing for 2h was 147.6 mPa.s. The gel breaking liquid is characterized by low viscosity, low surface tension, low interfacial tension, little residue content, and is conductive to the smooth flowback of the gel breaking liquid after fracturing construction. Compared with the conventional guanidine gum fracturing fluid system, this novel dendritic thickening agent fracturing fluid system has much lower residue content.
Structural Analysis of Historic Masonry and Technical Guideline Application: The Case of the Insula del Centenario [IX, 8] in Pompeii
Authors: Custodi Alberto , Castellazzi Giovanni , de Miranda Stefano , Ubertini Francesco
Published: September 2014

In this paper we present the study of an archaeological structure in Pompeii and we detail the difficulties encountered applying the Italian standards and guideline when designing the new roofing structure. Following the latest Italian standards and guidelines, about the assessment and mitigation of seismic risk of cultural heritage, the analysis of the Insula has been carried out. In particular, among all the studied structures, the attention was focused on the covering of the main hall where a prototype of a roofing structure covering a portion of the hall was installed near the remaining ruins of the house. Numerical models have been developed in order to track the effect of these new roofing structures on this ancient masonry structure.
In Situ Investigation of the Mechanical Strength of the Mortars: The Case of the Vaults of the Modena Cathedral
Authors: Colla Camilla
Published: September 2014

The 12th C. Modena Cathedral is a masterpiece testimony of early Romanesque architecture, artand civic values of the time. Following the inclusion in the UNESCO list in 1997, studies, surveysand maintenance works have started. The Emilia’s seismic events of May 2012 have happenedwhen the maintenance operations were already in an advanced phase. The quakes caused damageand re-opening of some historical cracks, in particular in the thin vaults of the naves, near thefaçade and at the junction between naves and choir and crypt. Fragments of brick, mortar from thejoints between bricks and even limited portions of a diagonal rib have fallen to the ground. In viewof seismic assessment and strengthening for improvement of the structural behaviour, detailedstudies of the vaults’ mortar became necessary. The investigation approach was minimal andpreservative, combining on-site close-up visual inspections and micro-destructive testing of themortar joints by mortar penetrometer. For this purpose, openings of 0.25x0.25 m2 in the renderlayer of the 23 vaults were created. The outcome has allowed differentiating between repair mortarsof different strength, used in different historic periods. The mortar resistance was very low butdifferent for lime mortar and gypsum. Values, divided in 3 classes of strength, were found tocorrelate well with the location and severity of the crack pattern and damage map in the vaults. Theresults were useful for a correct design (minimal and reversible) of the cathedral strengtheningintervention.
Behavior of Masonry Columns Repaired Using Small Diameter Cords
Authors: Borri Antonio , Castori Giulio , Corradi Marco
Published: September 2014

The innovative technique here illustrated is the result of historical evolution of ancient systems of hooping and is conditioned by design criteria that take into account the structural life in the respect of existing elements. It consists in the application of small diameter cords able to provide overlapping hoops at every course over the entire height of the column. Three series of uniaxial compression tests, with a total of 22 specimens, were conducted on model brick masonry columns with these variables: cross-section geometry, amount and scheme of confining reinforcement. Laboratory outcomes have shown how the investigated confining systems are able to provide significant gains in terms of compressive strength. Test results have been finally used to assess the reliability of the existing design equations suggested by Italian National Research Council for design of FRP strengthening of masonry columns.
On-Site Pull-Out Tests of Steel Anchor Spikes Applied to Brickwork Masonry
Authors: Panizza Matteo , Girardello Paolo , Garbin Enrico , Valluzzi Maria Rosa , Cardani Giuliana , Dalla Benetta Massimo , Casadei Paolo
Published: September 2014

Externally Bonded (EB) composite materials are becoming a widespread solution for strengthening interventions on masonry buildings, even Cultural Heritage structures, due to several positive aspects mainly related to their high strength-to-weight ratio. In recent years, beside common epoxy-based Fibre-Reinforced Polymers (FRP), steel-based composites have been proposed: they are composed by unidirectional high-strength steel cords that can be coupled to either organic (Steel Reinforced Polymers, SRP) or inorganic (Steel Reinforced Grouts, SRG) matrices, in relation to their optimized spacing. The bond behaviour of all these EB composites has a strong influence over the effectiveness of interventions, since the detachment of reinforcements from the substrate generally represents the weaker failure mechanism. In order to improve this aspect, several anchorage devices have been proposed, being spikes, among them, one of the most suitable for masonry supports. Spikes are made of a bundle of fibres partly in the form of a bar, to be inserted and glued into a hole drilled in the substrate, and partly loose, to be spread and connected to reinforcement strips. Despite their importance also from a design point of view and considering the variety of shapes and materials, there are still few investigations in this field, being clear that both the spike-to-reinforcement and the spike-to-masonry connections need to be studied. Focused on the spike-to-masonry connection, this paper is aimed at investigating the performance of steel cord spikes applied to existing clay brick masonry, by means of overall 39 pull-out tests carried out taking into account the bonded length (equal to the hole depth), the type of embedding material and the number of steel cords forming the anchorage. The main results of this experimentation are herein presented and discussed.
Fabric-Reinforced Cementitious Matrix (FRCM): A New Italian Guideline under Development
Authors: Ascione Luigi , Mancusi Geminiano , D'Aponte Anna
Published: September 2014

In addition toFibre-Reinfocedcomposite materials, which are made of long glass/carbon/aramid fibers embedded in a polymer matrix (FRP), the use ofFRCMcomposites (Fabric-Reinforced Cementitious Matrix) is becoming more and more widespread. As far as this specific case, the inorganic matrix guarantees many advantages, especially when dealing with masonry substrates, including a good compatibility from both a physical and a chemical point of view and the possibility of wet lay-up application. Despite their wide use in technical applications, the constitutive behavior and the failure mechanisms of FRCMs have not been adequately studied. As a consequence, a final assessment upon which criteria have to be used for verification and qualification ofFRCMsis still missing. In the context of a recent experimental program-still under development-cooperated by many Italian academic laboratories, that is aimed at detecting the main features of the constitutive behavior of these materials, a discussion seems to be appropriate on the initial experimental results obtained at Salerno University on manyFRCMspecimens tested under uniaxial tensile loads.
Influence of Sample Thickness and Capping on Characterization of Bedding Mortars from Historic Masonries by Double Punch Test (DPT)
Authors: Sassoni Enrico , Franzoni Elisa , Mazzotti Claudio
Published: September 2014

For determination of compressive strength of bedding mortar used in historic masonries, a promising moderately-destructive technique is double punch test (DPT). DPT consists of loading prismatic samples of mortar (about 4×4×1 cm3) by means of two circular steel platens (typically 2 cm diameter) and then calculating mortar compressive strength as the ratio of the failure load to the cross section of the circular platens. In this study, the influence of mortar sample thickness and mortar sample capping on the reliability of results obtained by DPT was systematically investigated. The influence of sample thickness was assessed by comparing DPT results obtained for samples with 5, 10, 15 and 20 mm thickness with compressive strength determined by testing reference 4 cm-side cubes. Different mortars were considered (cement, lime-cement, natural hydraulic lime), in order to investigate a wide range of mortar mechanical characteristics. The influence of surface capping was evaluated on a lime-cement mortar by comparing compressive strength determined on reference cubes with strength obtained by DPT on proper samples, without capping and after capping with rubber, gypsum and cement. The results of the study indicate that sample thickness substantially influences mortar compressive strength determined by DPT, which may vary by up to three times depending on sample thickness. A good estimation of the actual mortar compressive strength was obtained when samples with thickness similar to the loading platens diameter were tested, which suggests that choosing the size of the loading platens for DPT based on the thickness of mortar joints under investigation may be an effective way for obtaining reliable estimations. As for the influence of surface capping, in those cases where no mortar sample regularization is possible, because of the poor quality of the mortar, the results of the study indicate that sample capping actually seems necessary in order to avoid significant underestimations of mortar compressive strength. Considering the higher practicality offered by gypsum with respect to rapid-setting cement for surface capping, the use of gypsum seems preferable.
Experimental Analysis of the Bond Behavior of Glass, Carbon, and Steel FRCM Composites
Authors: D'Antino Tommaso , Pellegrino Carlo , Carloni Christian , Sneed Lesley H. , Giacomin Giorgio
Published: September 2014

In recent decades, the construction industry has witnessed a rapid growth of interest in strengthening and retrofitting of existing reinforced concrete (RC) and masonry structures. Fiber reinforced polymer (FRP) composites have gained great popularity, and several studies are now available in the literature on their use in strengthening and retrofit applications. Promising newly-developed composite materials are represented by the so-called fiber reinforced cementitious matrix (FRCM) composites. FRCM composites are comprised of high strength fibers embedded within a cementitious matrix that is responsible for the stress transfer between the existing structure and the strengthening material. FRCM composites are still in their infancy, and very limited results are available in the literature on RC and masonry strengthening applications. This study presents an experimental campaign conducted on different FRCM composites comprised of glass, carbon, or steel fibers embedded within two different cementitious matrices and applied to concrete prisms. The single-lap direct-shear test was used to study the stress-transfer mechanism between the FRCM composite and the concrete substrate. Two different composite bonded lengths were investigated. Debonding occurred at the matrix-fiber interface for some of the composites tested and at the concrete-matrix interface for others. This work contributes to the study of the bond behavior of FRCM composites, which represents a key issue for the effectiveness of FRCM composite strengthening.
Recent Developments in F.E. Analysis of FRP Reinforced Masonry Vaults: Case Studies in Italy
Authors: Milani Gabriele , Tralli Antonio
Published: September 2014

Aim of the present paper is the analysis of a series of existing masonry cross vaults exhibiting meaningful structural deterioration and diffused crack patterns, by means of an advanced non-linear and limit analysis software. The approach utilized is a non-standard and non-commercial one and bases both for the non-linear and limit analysis procedure on a FE discretization of the domain by means of rigid infinitely resistant wedges, where all the non-linearity is concentrated on interfaces between adjoining elements [1-3]. When dealing with the non-linear code, a sequential quadratic programming scheme is used at each iteration in order to deal with the deterioration of mechanical properties of interfaces, provided that the actual non-linear behavior is approximated by means of a linear piecewise constant function. Some real case studies of historic buildings in Italy are discussed. The first case study is represented by the structural analysis of a series of existing masonry cross vaults constituting the roof system of the ground floor of the former Caserma Lorenzini (ex Convent of S. Lorenzo) in Lucca, Italy, at the moment subjected to a wide restoration intervention within the so called Piuss project. The second is represented by the cross vaults of a 12th century masonry sighting tower damaged by the 20th may 2012 Emilia earthquake. This medieval tower, called Torre Fornasini, is located in the municipality of Poggio Renatico, about 10 km from Ferrara.
A Force-Based Equivalent Frame Element for Push-Over Analysis of Masonry Structures
Authors: Addessi Daniela , Mastrandrea Alessandro , Sacco Elio
Published: September 2014

A new macro-element based on the equivalent frame approach is presented to analyze the nonlinear structural response of masonry panels under monotonic lateral loadings. A nonlinear elastic response is assumed for the masonry material and the sectional response of the beam is derived performing analytical integration. A two-node equilibrated force-based (FB) beam finite element (FE) is formulated. The FE is composed of a central flexible part, characterized by a no-tension constitutive relationship, and a lumped nonlinear shear hinge arranged in series, in order to capture the main flexural and shear nonlinear mechanisms characterizing the masonry panel response. Some applications on experimental prototypes are presented, showing a very satisfactory agreement between the numerical results and the experimental outcomes.
Debonding between FRP and Underlying Masonry: First Results of a 3D Finite Element Model
Authors: Carloni Christian , Casacci Susanna , de Miranda Stefano , Di Tommaso Angelo , Gentilini Cristina , Ubertini Francesco
Published: September 2014

Experimental and numerical results show that the predominant failure mode of FRP strengthened masonry structures is the interfacial debonding, which occurs prior to reaching the compressive strength of the substrate and/or the tensile strength of the FRP composite. In this paper, a three-dimensional numerical model is developed to simulate the experimental response of direct shear test of FRP-masonry joints and. A damage model is adopted for both mortar and bricks characterized by a different behavior in tension and compression.
Dynamic Parameters of Pultruded GFRP Structures for Seismic Protection of Historical Building Heritage
Authors: Boscato Giosuè , Russo Salvatore
Published: September 2014

The seismic events in the last decades evidenced the vulnerability of the architectural heritage with respect to these phenomena. Therefore, timely provisional and permanent interventions are often required in post-seismic scenarios.In response to the call for more efficacious solutions, a great deal of interest has been given to glass fiber-reinforced polymers (GFRPs) composite. GFRP composites offer the advantage of high strength, low self-weight and durability.This research proposes some first evaluations on the dynamic behaviour of pultruded FRPs (Fiber Reinforced Polymers) strut and tie spatial structure for seismic protection of historical building heritage. The dynamic identification has been carried out using the ambient vibrations test to measure the mode of vibration, frequencies, displacements and damping ratios of the structures. The Operational Modal Analysis (OMA) has been carried out to identify the modal characteristics through poly-reference Least Square Complex Frequency-domain (pLSFC) estimator.Basing on the experimental results the dissipative capacity has been evaluated through the calculation of the behaviour factorq.The experimental dynamic parameters were used to calibrate a numerical finite element model employed under the hypothesis of kinematic equivalence to evaluate theqfactor considering the elastic-brittle behaviour of FRP material. The dissipative capacity of structure was assigned to the global geometric configuration - frame with concentric diagonal bracings - through the strength hierarchy criteria locating the dissipative zones in the tensile diagonals. The analysis was carried out considering some typological variations to investigate the variability of the behaviour factorq.
Fiber Orientation Effect in the Dynamic Buckling of Debonded Regions in Laterally Loaded FRP Strengthened Walls
Authors: Elmalich Dvir , Rabinovitch Oded
Published: September 2014

This paper studies the effect of lamination and fiber orientation on the geometrically nonlinear dynamic response of debonded regions in walls strengthened with FRP. The paper adopts an analytical/numerical approach and uses a specially tailored finite element formulation for the layered structure. By means of this analytical/numerical tool, two strengthening layouts for a wall segment subjected to a dynamic shear loading are compared. In the first layout, the fibers are oriented along the width and height of the segment and in the second one, they are oriented along its diagonals. The analysis reveals that the two layouts are involved with significantly different critical points and significantly different dynamic post-buckling behaviors. Specifically, it shows that the diagonal layout, which better serves the shear loading scenario, is involved with a much smaller critical displacement and a dynamic post-buckling behavior that is governed by the stiffer compressed and tensed diagonals.
Effect of the Presence of Mortar Joints in the Bond Behaviour of Tuff Masonry Elements
Authors: Ceroni Francesca , Garofano Angelo , Pecce Marisa , Procaccini Gian Marco
Published: September 2014

In this paper, the bond behaviour of masonry elements made of tuff stone and bonded with different types of FRP fabrics (glass, carbon, basalt) has been investigated through an experimental campaign. Tuff is a natural stone representing a very common base material for the construction of masonry buildings in Southern Italy and many Mediterranean areas. Two series of specimens have been tested: 1) single blocks and 2) prisms made of three blocks and two mortar joints. The tests have been carried out according to a single-lap shear scheme according to a push-pull set-up. Presence of a plastering was also investigated for both series. The experimental results have been examined in terms of both debonding load and local stress transfer phenomena in order to evidence the performance of the different fibres and the effect of both mortar joints and plastering.
Artificial Ageing of Mortar Prisms Reinforced through Steel, Glass and Organic Fibres
Authors: Sinicropi Daniela , Perria Elena , Galassi Stefano , Paradiso Michele , Borri Antonio
Published: September 2014

The process of ageing in construction materials is natural and expected, and the technologies to contrast and reverse any damage due to the passing of time are well known in the field of civil engineering. This is true for structures themselves as well as the reinforcement technologies such as, for example, fiber reinforcements (FRP or FRCM). In fact, studies [1,5] have brought attention early on to severe mechanical characteristic reduction caused by the ageing process of specific resin matrices used in composite reinforcement materials, or, even more perilous, their exposure to extreme conditions of temperature. In this project, the authors have set up an experimental campaign on mortar prisms reinforced with different types of fibers and subjected to cycles of ageing through heat exposure. This paper presents the results obtained by three point flexural testing performed at the Testing Laboratory of the University of Florence, comparing the results of the reinforced and aged prisms with those of the non-aged and non reinforced prisms, providing a precedent on how ageing influences the structural behavior of fibers and mortar.
Synthesis, Characterization and Silanization Spinel ZnAl1.9Eu0.1O4
Authors: Santos P.T.A. , Araújo P.M.A.G. , Santos Polyana T.A. , Costa Ana Cristina Figueredo Melo
Published: September 2014

This paper aims to synthesize by combustion reaction and silanilized of the ZnAl1.9Eu0.1O4, with silane agent 3-aminopropyltrimethoxysilane. The characterization of materials before and after silanization was investigated. Nanoparticles ZnAl1.9Eu0.1O4 was obtained according to the theory of propellants and explosives using the synthesis combustion reaction. The samples were deagglomerated and passed through a sieve of 325 mesh and added to 3-aminopropyltrimethoxysilane, followed by heat shock treatment by ultrasonic and microwave. Subsequently centrifuged and dried at 150 ° C for 24 hours. The samples before and after the silane were characterized by X-ray diffraction, infrared spectroscopy and thermogravimetric analysis. The results indicate the formation of a major phase spinel normal ZnAl2O4, and the EuAlO3 peaks as secondary phase. The FTIR spectra for ZnAl1.9Eu0.1O4 have absorption bands below 1000 cm-1, and after silanization showed bands of C = O, axial strain - CN and Si-O bands, which proves the silanization. The thermogravimetric curves showed good thermal stability, with mass loss around 30%.
Glass Ionomer Cement – Development and Characterization Microstructural
Authors: Freire Waldênia P. , Fook Marcus Vinícius Lia , Barbosa Emilly F. , Araújo Camila S. , Barbosa Rossemberg C. , de Sousa Wladymyr J.B.
Published: September 2014

The Glass Ionomers Cements (GICs) are materials widely used in dentistry, have advantages such as fluoride release and chemical adhesion to the dental substrate. They are recommended as a restorative material, luting agent in prosthetic dentistry and also in medicine. However, there is need for developing new bone cements as an alternative or replacement to the current polymethylmethacrylate cements, therefore, the objective of this research was to develop an experimental GIC and characterization regarding morphology, chemical composition and crystallinity. This composite was characterized by X-ray diffraction (XRD), Infrared Spectroscopy Fourier Transform (FTIR) and optical microscopy (OM). For comparative study, was used the GIC Vidrion R (SS White) in the control group. These cements are presented in semi-crystalline diffraction patterns, the FTIR spectra observed characteristic bands of these materials and microstructural study of the cements showed homogeneous distribution of filler in the polymer matrix, corroborating with the literature.
Optimization of Aluminum Anodizing and Coloring Process Employing Organic Pigment
Authors: Alves Guilherme José Turcatel , Antunes Sandra Masetto , Gallina Andre Lazarin , Maia Guilherme Arielo Rodrigues , Rodrigues Paulo Rogério Pinto
Published: September 2014

The process of aluminum anodizing forms an oxide layer constituted of nanotubes where it is possible to insert compounds, amongst these are the pigments and dyes. This study has as its main aim to study the behavior of aluminum alloy 6000, anodized and dyed with monolite red in Na2SO4 0.5 mol L-1 and pH = 4. The techniques employed were: anodic potentiostatic polarization, open circuit potential, chemometry, polarization resistance and optical micrograph. The factorial planning was proposed using four variables (anodizing time, current density, electrolyte concentration, and dye), the response to the planning was the charge transfer resistance. Polarization curves revealed that the anodized and dyed aluminum samples are much more resistant than the non-anodized aluminum. Optical microscopy analyses demonstrated that the dissolution of dye occurs in the solution, but not enough to break the film. As the main result, efficient coloring of aluminum parts was verified with reduction in costs in relation to the energy employed in the process, associated to reduction in time spent for the anodizing process, which makes it suitable to increase industrial production of dyed aluminum parts.
The Metallographic Technical Preparation Influence on the Zinc Hot Dip Deposited Layer Morphology
Authors: Braunstein Faldini Sonia , Vatavuk Jan , Konno Anne Naomi
Published: September 2014

The metallographic technical preparation influence on hot dip deposited zinc layer intermetallic phases investigation and distribution was the aim objective in this work. The base material was SAE 1020 carbon steel and specimens with and without zinc layer detachment was selected after the submission to adherence test base on hammer impact. Three different grinding and polishing technique were employed and the phases were investigated by optical metallographic technical as well as through a scanning electron microscope with an EDS system. The different metallographic techniques have no effect on the phase determination and distribution.
Effect of Aging Treatment on Inconel 718 Superalloy: Application in Elevated Temperatures
Authors: Caliari Felipe Rocha , Candioto Kátia Cristiane Gandolpho , Reis Danieli Aparecida Pereira , Couto Antônio Augusto , de Moura Neto Carlos , Nunes Carlos Ângelo
Published: September 2014

This work studies the effect of double aging heat treatment on superalloy Inconel 718. The heat treatment followed two steps: Solid solution at 1095oC for 1h, and two steps of aging 955oC/1h - 720oC/6,5h - 720oC/1,5h + 620oC/8h. Parameters such as grain size, secondary phases distribution and qualitative analysis via SEM/EDS and Vickers hardness are used in order to evaluate the microstructural evolution. The results show increase of grain size and Vickers hardness, as well as a better distribution of secondary phases along the matrix.
Effects of Multiple Pre-Sintering Heat Treatments and Consolidations Applied to Nicralc Alloys Processed by Mechanical Alloying
Authors: Kwiatkowski da Silva Alisson , Cintho Osvaldo Mitsuyuki , Vurobi Selauco , Pereira Joéverton I. , Capochi José Deodoro Trani
Published: September 2014

NiCrAlC alloys are economical alternatives nickel superalloys to Co family StellitesTMalloys, they are constituted by a dispersion of chromium carbides in a Ni3Al (γ’) intermetallic matrix. Mechanical Alloying (MA) allows better control of the carbides size and distribution in NiCrAlC matrix after sintering, although high porosity has been observed after uniaxial compaction and sintering of NiCrAlC alloys processed by MA. This research investigated the employment viability of pre-sintering heat-treatments followed by a new uniaxial compression in order to reduce porosity after final sintering. The characterization of the processed material by optical metallography and quantitative stereography appoints to the viability of this conception to reduce the porosity of NiCrAlC alloys processed by Mechanical Alloying.
Synthesis and Characterization of Ionic Crosslinked Chitosan Scaffolds
Authors: Fideles Thiago Bezerra , Fook Ana C.B.M. , Furtado Gloria T.F.S. , Pinheiro Italo M.F. , Fook Marcus Vinícius Lia
Published: September 2014

Chitosan has been the focus of an extensive research in recent years, especially due to its biodegradability, biocompatibility and the possibility to be processed in many form, shapes and sizes. Besides, chitosan can ben chemically modified and this modification through crosslinking can produce materials with a wide variety of properties. The aim of this present work was to produce and characterizing ionic crosslinked chitosan scaffolds. Chitosan scaffolds were prepared by the freeze drying technique and crosslinking was introduced by a chemical reaction with sulfuric acid solution. The non-crosslinked and crosslinked chitosan scaffolds were characterized by Fourier Transformed Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). According to FTIR results, an effective reaction between the sulfate ions and chitosan scaffolds was achieved with visible changes in the spectra. This reaction also could be seen on EDS results with sulfur peaks presents in all the crosslinked samples. The SEM results showed that the crosslinking reaction doesn ́t modified the chitosan scaffolds tridimensional structure.
Influence of Calcium Concentration on the Structural and Electrical Properties of PZT Ceramic
Authors: Silva Margarete S. , Cavalheiro Alberto A. , Zaghete Maria A. , Cilense Mário , Longo Elson , Cavenago Gustavo F. , Dias Rafael G. , Silva Lucas L. , Motta Fabiana V.
Published: September 2014

Lead zirconate titanate, with Zr/Ti ratio of 53/47 was prepared by the polymeric precursor method. The powders were doped with 0, 0.2, 0.4 end 0.6 mol% of Ca2+and characterized by XRD. The percentages of tetragonal and rhombohedral phases were calculated through Rietveld refinement. A systematic study of the effect of dopant on the ferroelectric and piezoelectric properties of PZT was carried out. The remanent polarization, planar coupling factor and piezoelectric charge constant, increase with dopant concentration.
Use of the Processed Waste from Kaolin and Granite Sawing in the Manufacture of Tubular Ceramic Membranes
Authors: Chaves Alexsandra Cristina , Neves Gelmires Araújo , Lira Hélio Lucena , Oliveira Danielle Nascimento Silva , Mendonça Ana M.G.D.
Published: September 2014

The incorporation of waste from various industrial activities in ceramic products comes as a technological alternative to reduce the environmental impacts caused by the indiscriminate disposal of wastes in the environment. The kaolin and granite processing industries have been mentioned as sources of contamination and pollution, due to the enormous amounts of wastes they produce. The use of these wastes as raw material and its transformation into products that can be commercialized and/or show economic viability, presents as an alternative to the industries. The aim of this work was to use ceramic masses incorporated with kaolin waste (35%), granite (35%) and bentonite (30%) for the confection of tubular ceramic membranes using extrusion as production process. The ceramic mass was characterized through analysis techniques of thermogravimetric, chemical, particle size and X-ray. The membranes produced, after sintering in temperatures of 850, 900, 950 and 1000oC, were submitted to characterizations of scanning electron microscopy, mercury porosimetry and permeability test by tangential flow. The preliminary result of the particle size analyses identified that the ceramic mass presents an average particle diameter of 37.00μm. The membranes presented porosity of approximately 32%, and average pore diameter within the ultrafiltration range.
Microstructural and Mechanical Characterization of the Niobium Cold Deformed-Swage
Authors: Garcia Borges Dalton , Baldissera Márcia Regina , Rodrigues Geovani , Melo Mírian de Lourdes Noronha Motta , Ribeiro Lourenço Rayana Fernanda , Silva Gilbert
Published: September 2014

The refractory metals and their alloys show excellent mechanical behavior in high temperatures and high resistance to corrosion and to wear and good thermal conductivity. The metals that constitute this group are, traditionally, tantalum, molybdenum, tungsten and niobium. Niobium (Nb) is a metal with 2468°C melting point, density 8.57 g/cm3 and CCC crystalline structure, is characterized by its excellent ductility and reasonable mechanical resistance in high temperatures. Due to these properties, o Nb is applied in chemical, nuclear and electrical industry and in the superconductor wire production. One of the processes used in niobium plastic deformation is the swage that consists in one direct deformation process, which can be done at hot or cold temperature, used to modify the transversal section area of bars, tubes and wires. The microstructure evolution during a plastic deformation is very important in the relation of deformation mechanism, mechanical property and texture formation. The aim of this work is to evaluate the microstructural and mechanical behavior of metal cold rotary forging – swage using the techniques of Scanning Electronic Microscopic – SEM e microhardeness Vickers. Metallographic analysis of the microstructure of Nb after deformation of 96.4%, shows a distorted shape called "ripple". The Vickers microhardeness results indicate that there is a gradual increase in the microhardness of Nb up to 80% reduction in area taking place stabilization after this value. It may be noted that in both directions, the center of sample had higher hardness values
High-Velocity Impact Comminution of Magnetite
Authors: Meech John , Sadrai Sepehr , Zadeh Bahador Mousavi
Published: September 2014

Conventional comminution (crushing and grinding) uses compressive forces to initiate and propagate cracks throughout the rock mass, yet the material actually breaks under tension since this strength characteristic is about 10 percent of the compressive strength. Converting a compressive force into a tensile one is inefficient - of the order of 1 to 2 percent. On the other hand, blasting shows energy efficiencies of the order of 10 to 20%. Part of this difference is due to forces being applied directly in tension (from the inside-out), but also because the velocity of impact is orders of magnitude higher (10,000 m·s-1versus 10 m·s-1), i.e., the rate of energy input is very high (micro-seconds vs. seconds in conventional comminution). This paper reports on studies that show how the energy efficiency of comminution can be enhanced by high-velocity impact. This research project has carried out investigations into the relationship between energy efficiency with energy input level and impact velocity during rock fragmentation by metal projectiles. The project has also examined rock-on-rock breakage. Samples of magnetite particles of varying weights and size distributions were impacted by a projectile at velocities from 50 m·s-1to 400 m·s-1. The specific surface area of the sample was measured before and after each experiment, and the energy recovered as new surface energy (energy efficiency) was calculated. The results indicate that energy efficiency increases to about 5% as impact velocity enters the range from 200 to 300 m·s-1. This efficiency is over 3 times that observed in conventional comminution. Above this velocity, the efficiency begins to fall off although significant comminution at higher than normal efficiencies are still attained. The improvement results from both increased rate of energy input and increased impact velocity. Rock-on-rock impacts using a glass projectile shows that the energy of new surface generation is distributed between the projectile and the sample to a combined level similar to that of the steel-on-rock tests in which all the useful energy is retained within the sample. Suggestions are given as to how this energy improvement could be scaled-up into an impact crusher.
“Cement-Free Product” for Settlement of Ceramic Tiles: An Approach for Greener Construction
Authors: do Nascimento Otávio Luiz , Mansur Alexandra Ancelmo Piscitelli , Sander Mansur Herman
Published: September 2014

Increased public awareness of the threats posed by global warming has led to greater concern over the impact of anthropogenic carbon emissions on the global climate associated with the level of carbon dioxide (CO2) in the atmosphere. Hence, without radical market, technological, and cultural changes, the CO2 concentrations are expected to rise to unbearable levels within just few decades ahead. The production of cement is estimated to be responsible for approximately 5% of the global carbon dioxide emissions. Consequently, aiming for creating a more sustainable world, engineers and scientists must develop and put into use greener building materials that may revolutionize the entire construction industry. This study presents an innovative product for settlement of ceramic tiles as a potential alternative for replacing the conventional cement based mortar in some specific building applications. Essentially, the novel system is based on a double face polymer-adhesive sheet (“cement-free product”). Thus, the main goal was to evaluate the performance and estimate the durability of the developed system. Pull-off tests were conducted in order to compare this new system to the traditional one, with polymer modified mortar, under different procedures and conditions of cure. In addition, both systems were modeled using Finite Element Method (FEM) to obtain the stresses at the interface between ceramic-tile and adhesive. Based on the results, the recommended limits of bond strength for the innovative “cement-free product” of ceramic tile installation could be lower than those specifications used for the equivalent mortar systems. Therefore, these results give some preliminary evidence that by using the new “cement-free” product for ceramic-tile installation may lead to some increase in the productivity and, more important, in the sustainability of a relevant sector of the construction industry.
Challenges in the Feasibility of Bituminous Shale as a Source of Oil
Authors: Passos Alexandre O. , Paulino Jonas R. , de Tomi Giorgio
Published: September 2014

A discussion about the current scenario of oil shale as a source of oil is carried out here, pointing out some challenges to enable its feasibility aiming to promote the development in the mining industry sector. Considering factors such as production costs, petrol prices, environmental damage, among others, an intractable exploration occurs in most cases. More specifically in Brazil, these resources may play a key role to the nation's interests. With an economy notably in full growth, the country has one of the largest deposits of oil shale in the world. Under this context, although the research analyzes this question in a global way, its focus is to study factors that may enable an economic feasible exploration of oil shale mainly in Brazil.
Synthesis of LaNi0,6Fe0,4O3-δ (LNF64) by Pechini Method for Use as Cathode in SOFC´S
Authors: Ramos Kethlinn , Wendler Leonardo Pacheco , Chinelatto Adriana Scoton Antonio , Chinelatto Adilson Luiz
Published: September 2014

The solid oxide fuel cell are an alternative of production clean and efficient energy, because converts chemical energy in electrical energy. A fuel cell is formed basically by an electrolyte, a cathode and an anode. The main electrolyte used for SOFC manufacturing is the ZrO2-Y2O3. The materials for electrode manufacturing must possess thermal expansion characteristics close to electrolyte and have high electrical conductivity in operating temperature. Recently, the perovskite LaNi0,6Fe0,4O3-δ, has attracted interest for application as cathode in SOFC ́s for has a high electronic conductivity and a thermal expansion coefficient whish for the zirconia electrolyte. This work aimed to LaNi0,6Fe0,4O3-δobtained by Pechini method. The powders were characterized by differential thermal analysis, thermogravimetric analysis, x-ray diffraction, energy dispersion X-ray fluorescence spectroscopy, helium pycnometry and scanning electron microscopy. The results showed powders obtained with perovskite formation when calcined 600°C during 2 hours.