bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Simulation of GH4169 Alloy Section of Hot Roll Forming
Authors: Gao Lei , Pang Yu Hua , Sun Lie , Tian Da Rong
Published: March 2014

A hot roll forming process of GH4169 alloy complex sections described in this paper is a new forming process of GH4169 alloy sections. The rolling 6o, 7o, 8o pass and rectangular, wedge-shaped, irregular blank are designed. Rolling models has been developed using the rigid-plastic finite element method on DEFORM. The rolling force and pass fullness and the distribution of various field-variables such as temperature and effective strain can be obtained from the simulated result. The finally optimizing rolling process shows that the pass slopes with 6o on the roll, the cross-section of the blank is irregular, and the rolling processes are using one pass to do two passes rolling through changing the value of the roll gauge. The simulated results show the temperature of the workpiece is about 1030~1080°C, the inner temperature is greater than the surface temperature, the surface temperature is minimum, and the effective strain is about 0.3~2, which meet the requirement of the GH4169 alloy structure property, and they are significance to the other hot roll forming process of GH4169 alloy sections.
The Transmission Spectrum of Symmetrical Structured One-Dimensional Photonic Crystals of Positive and Negative Materials
Authors: Su An
Published: March 2014

The transmission spectrum of symmetrically structured one-dimensional photonic crystal (AB)m(BA)m consisting of positive and negative materials was studied with transfer matrix method theory. The result shows that a single narrow transmission peak constantly appears at the frequency of uneven ω/ω0, while a broad transmission peak appears at the frequency of even ω/ω0. When periodicity m or refractive index nA of Layer A increase, the narrow transmission peaks in the spectrum become sharper and the broad peaks become narrower; as refractive index nB of Layer B rises, all the peaks in the spectrum become broader; and when the thickness dA of Layer A medium thicken, the transmitting peaks move towards alto frequency,while with the thickening of dB of Layer B medium, these peaks move inversely towards low frequency. Furthermore, in these two circumstances, the transmitting peaks at right alto frequency move faster; however, peaks remain unchanged when both dA and dB concurrently thicken. All these optical transmission characteristics of symmetrically structured one-dimensional photonic crystals can offer guidance to designing adjustable super-narrow optical filters, broad band filters and optical switches.
Preparation of PVA Nanofiltration Membrane with Good Solvent Resistance
Authors: Zhang Jian Dong , Wang Li
Published: March 2014

Polyvinylalcohol (PVA) with good solvent resistance was used in preparation of nanofiltration membrane. The preparation parameter such as PVA concentration, cross-linking agent concentration and reaction time are studied in detail. When the composite membrane was prepared under optimized conditions and tested at 0.4 MPa and 20 °C, the flux of the NF membrane was about 15 L/m2h and the Na2SO4 rejection of it was about 53.3%.
Evaluation of Physical Properties of Adobe Chemically Stabilized with Synthetic Termite Saliva
Authors: Corrêa Andréa A.R. , Guimarães Bárbara Maria Ribeiro , Scatolino Mario Vanoli , Duarte Moisés G. , Lopes Thamirys A. , Mendes Lourival Marin
Published: March 2014

Adobe (raw mud brick) is a non-conventional technology that awakens a wide interest in sustainability constructions. However is important to improve the physical properties to reduction its water absorption and capillarity. The stabilization of adobe with products that don`t harm the environment and improve these physical properties must be goal for studies. Then Dynasolo DS328®known as synthetic termite saliva" is a chemical stabilizer produced in Brazil that can be a good option. This composition with vegetal oils is non-toxic, hydrophobic and has cohesive properties. The product is a high-concentrated liquid, water soluble and non-flammable. Therefore, this research aimed to compared the synthetic termite saliva" incorporation at four different concentrations: 1:2000; 1:1500; 1:1000 and 1:500 with adobes without stabilization. The reagent chosen was an aluminum sulfate at 1:5000 for all treatments. The adobe soil is a Red Latosol cambisol in natura and corrected to 50% fine sand fraction. The ideal moisture content is variable, ranging from 50% to 40% according DS328®increase. Adobes were submitted to water absorption, capillarity and linear contraction field tests science-based. This research confirmed the cohesive properties of chemical stabilization with synthetic termite saliva". It improved density and reduced the water absorption, capillarity, mass loss and linear shrinkage. The better treatment was 1:500 concentration.
Determination of the Delamination Percentage of Compacted Bamboo Guadua Using Extended Field Digital Images Processing
Authors: Torres Edgar , Luna Patricia , Takeuchi Caori
Published: March 2014

The percentages of delamination of Compacted Bamboo Guadua were calculated using digital images processing. Three processes were done in the development of this project: tests of delamination, digital image pre-processing and digital image processing of the images acquired. The test of delamination followed the ASTM 5824. The digital image pre-processing was supported on the acquisition of sequences of images, doing a sweeping of the samples, and finally the digital processing worked in the generation of panoramas with sequences of images acquired from the sample. Additionally, the total area from the sample was measured digitally, the segmentation and the measurement of delamination area were done, finding the ratio between the delamination area and the total area of the sample, and obtaining the value of percentage of delamination per section. Digitally, the obtained values for samples made with fibers obtained from Stick (Varillón), Top (Sobrebasa), Middle (Basa) parts and mixture of them were 16.97%, 9.96%, 5.96% and 8.64% respectively.
Heritage Earth Construction and Hygrothermal Comfort: The Challenge of Rebuilding in Central Chile
Authors: Whitman Christopher J.
Published: March 2014

According to the latest official census of 2002, earth construction represented 5.5% of the Chilean building stock. These buildings of traditional construction techniques of unfired earth and straw blocks (adobe), rammed earth (tapial) or wattle and daub (quincha) form a large proportion of Chile’s National Monuments and heritage buildings. In addition to their heritage value, these buildings with their high thermal mass, respond well to the climate conditions of both the altiplano of northern Chile and the Central Valley, zones with high diurnal temperature oscillations, with typical daily temperature differences of up to 20°C. However following the 2005 earthquake in Tarapacá, northern Chile and that of the 27th February 2010 in Central Chile a serious rethink has been required as to the retention and restoration of adobe buildings. Public opinion has labelled earth construction as unsafe and most reconstruction to date has taken place with prefabricated timber solutions which lack the necessary thermal mass to respond well to the climatic conditions. At the same time research into the structural integrity, seismic resistance, maintenance and the living conditions provided by earth construction has been undertaken. In this wider context this paper presents the compilation of international and Chilean research into the hygrothermal properties of adobe construction, in addition to the authors insitu measurements of the temperature and relative humidity in two surviving adobe dwellings in the earthquake hit village of Chépica located in Chile´s Central valley. These measurements are compared with those of a dwelling rebuilt with straw bales and earth render in the same location. Based on this information the paper studies the challenge of rebuilding and restoring heritage buildings whilst providing occupants with the necessary levels of environmental comfort.
Evaluation of Concrete Produced with Pebble from the Region of Tangará da Serra-MT
Authors: Carvalho Karita P. , Albuquerque Albéria C. , Costa Juzélia S.
Published: March 2014

The distance of the points of delivery of aggregates stimulate entrepreneurs to search for new alternatives that meet their needs, with low cost and quality. This study rescues the use of pebble on the concrete in the region of Tangará da Serra - MT. Willing to collaborate with the industry, a concrete was produced using methods of particle packing in order to provide to the manufacturer a proposal that makes possible the quality of the product supplied. The aggregate and the cement were tested according to their physical and mechanical characteristics, while the properties of the hardened concrete were evaluated according to their mechanical resistance. The results indicated that the mix with pebble aggregate have suitable properties to be used as a structural concrete. Earnings due to rationalization, quality and reducing manufacturing costs are factors that will contribute to the product acceptance in the market.
Evaluation of the Influence of Heavy Metals in the Hydration Process of Mortars through Electric Measurements
Authors: Venâncio Caroline , Rocha Janaíde Cavalcante , Cheriaf Malik
Published: March 2014

The building materials are evaluated for their mechanical behavior, durability and most recently, about the risk of environmental contamination. Some heavy metals can be found in the waste added in cementitious matrices. The techniques of introducing the wastes in cementitious matrices allow the stabilization and solidification of the contaminants. However, this immobilization should be monitored and the effectiveness of this method is investigated by carrying out leaching tests, among other procedures. The objective of this study was to analyze the influence of heavy metals in the hydration process of cementitious matrices by way of tank tests carried out on mortar, previously contaminated with the heavy metals Zn2+, Cr3+ and Pb2+ at a concentrations of 20, 40, 80 and 160 ppm and to propose the use of electrical impedance spectroscopy (EIS) coupled to represents the leaching mechanisms. In the electric test was used an alternating current, varying the frequency of 200 kHz to 2 MHz. For assess the leaching behavior were performed the tank test (NEN 7375). The results showed that the heavy metals how the zinc and lead, can retard the setting time of the mortars and this was observed in the impedance spectrums throughout cure time of mortars. During the tank test the electrical impedance of the contaminated mortars were lower than the reference mortar and the output of portlandite caused an increase in the electrical impedance values. The electrical test is a not destructive technique, faster than the leaching tests and in the future, it can be performed to aid environmental testing.
Bamboo Mast for Lightweight Arquitecture
Authors: Moreira Luis Eustáquio , da Silva Fernando José , Rodrigues Francisco Carlos
Published: March 2014

Bamboo is a pipe produced by solar energy. It is a plant of the graminae family which grows up all over tropical and part of subtropical regions of the world in more than 1250 species. High biomass production, high mechanical resistance, low specific weight and easy workability has done of bamboo a promise to future generations in relationship to sustainable construction systems. Bamboos of the Phyllostachys pubescens species are one of the most resistant and straight axis bamboos, used in China as material construction and other applications, as paper and fabrics. They are the most commercial bamboos of China and its forests covers 5,6 millions of hectare in that country. This exotic species is met on small plantations in Rio de Janeiro and São Paulo states of Brazil. Many characteristics turns bamboo a smart structural element: high resistance/weight ratio; natural nodes spaced along the culm which avoids local buckling and graded distribution of the fibers from inner to outer side of the thickness wall. So, the application of bamboos as tensile structures supports is a coherent choice since these modern tents characterize a lightweight architecture. Some structural bamboos can attain even more than 15 meters long with 10 cm mean diameter. To increase the load capacity of this slender bar and make feasible bamboo use as masts for tensile structures, an hybrid mast using bamboo as axis and 4 steel cables along of was designed and tested in the Structural System Laboratory LASE, and Structures Experimental Analysis Laboratory LAEES, respectively. In this paper it will be presented the results of the mechanical tests for 2 different masts with 6 meters long. Both masts have the same design but important differences which will be discussed in the paper.
Alkaline Activation of Aluminum and Iron Rich Precursors
Authors: Gomes Kelly Cristiane , Torres Sandro Marden , da Silva Zaqueu Ernesto , Perazzo Barbosa Normando , Lima Filho Marçal Rosas Florentino
Published: March 2014

The alkaline activation of aluminosilicates materials has been motivated by their enhanced thermomechanical properties. Despite the majority of studies comprise the evaluation industrial byproduct of precursors (fly ash and slag), metakaolin (Al2O3.2SiO2) is acknowledged to have structure and chemical composition characteristics that make it very reactive as far as alkaline activation is concerned. In tropical regions of the earth, as is the case in northeastern Brazil, there are some waste (kaolin waste, red brick waste and weathered tropical soils) whose alkaline activation potential have not yet been fully studied. These sources are known to have other metals such as iron in its structure, which might affect the alkaline activation. This paper aims to evaluate the potential of alkaline activation of these wastes. Chemical and structural characterization were performed by means of x-ray fluorescence, x-ray diffraction, infrared spectroscopy and compressive strength. The results indicate that all studied waste presented significant potential as precursor material for alkaline activation.
Use of Compactation Tests for Defining Process Mixtures Parameters to Concrete Blocks
Authors: de Almeida Marconi Oliveira , de Sousa Jose Getulio Gomes , Lima Lucas C.
Published: March 2014

In recent years, Brazil has been going through a period of economic growth and is now facing the acceleration of this development, the presence of engineering in all its areas, becomes crucial to sustain this condition. A primary form of this chain, the use of conforming materials, joins an entire production process which should result in works that have as their main focus the minimum quality of the finished product. For this reason, definition and understanding of aspects such as mixture and all parameters involved in the production of materials becomes critical. For concrete block, there is a series of steps that will culminate in a final product quality, always appropriate to the project while respecting normative aspects. Within these stages of production of concrete blocks, using the method of lower volume of voids, this paper will explore the definition of the best mixes of aggregate/coarse and the definition of the moisture content of the mixture and the correlation of compacted test specimens, with blocks produced using specific standards for soil cement NBR 12023/92 [ and 12024/92 [. In this study we observed that there is a correlation of 95.30% compressive strength of the compact tests specimens with the concrete blocks producing in vibro press. This correlation allows us to design a dosing process using a previous best volume of material due to the smaller size of CPs, streamlining and minimizing the costs of the definition of dosing parameters. In relation to the moisture content, it was noted that the value set in the compaction test must be adjusted when the blocks are made in the press, since energy of compaction is larger in that case. Thus for the production of the blocks, humidity value was 10.71% less than that defined by the compaction test.
Use of Construction and Demolition Waste in Lateritic Concrete
Authors: Cândido Taíssa Guedes , Coutinho Yane , das Chagas Filho Milton Bezerra
Published: March 2014

In recent decades the problem of construction and demolition waste has been receiving more attention due to possible ecological and economic damage caused by them. This is because they are produced in large quantities and often receive inadequate disposal, being deposited illegally in vacant lots, public places and even in areas of environmental preservation. The practice of recycling of construction and demolition waste (CDW) by construction is an alternative that minimizes the amount of waste generated and the impacts caused by them. Moreover, the introduction of alternative materials might reduce the production costs of construction. In Brazil, there is great availability of lateritic concretions. This material, according to some studies, proved to be a viable alternative to be used as coarse aggregate in concrete production. In this study, it is used the CDW as a filler to replace 10% of Portland cement and, as coarse aggregate, lateritic concretions. Tests of physical properties of coarse and fine aggregates and determination of the mechanical strength of hardened concrete were made. The construction and demolition waste used as filler to replace the mass of cement in the mixture proved to be a viable alternative.
Science and Technology Observatory for ''NOCMAT'' in Brazil: Role and Proposed Framework
Authors: Ohayon Pierre , Barreiros Danielle Sampaio , Ghavami Khosrow
Published: March 2014

The indicators for Science and Technology Innovation (S&T) used for decision-making within the national system of research and innovation related to Non-Conventional Materials and Technologies (NOCMAT), do not concern only the federal political sphere, but also research groups of universities, research institutes and scientific and technical associations. These agents influence is frequently insignificant for decision making when compared to the dominant and centralizing industries which have created their proper indicators for justifying the application of conventional industrialized products. A culture of NOCMAT indicators should be disseminated into the scientific and social communities so that decisions at all levels should be based on relevant, reliable and transparent information, notably at the regional level. The main objective of this paper is to establish the terms of reference of the "NOCMAT Observatory" for Novel Construction Materials & Technologies for Sustainability not yet existing in Brazil, notably defining its role, dynamic organizational framework, "products" and services to be provided.
Standards Questions when Developing a New Market; The Lessons for Non Conventional Materials
Authors: Mione Anne
Published: March 2014

This contribution exposes the strategic relational questions associated with the creation of a voluntary standard. We first argue that the creation of rules is required to develop a new market. The development of new markets for non-conventional materials would beneficiate from the development of new standards. Yet, the creation of voluntary standards may entail competitive relational choices that the creators of standards are generally unprepared to handle. We thus consider two situations where voluntary standards have generated competitive interactions between rival standards organizations and try to suggest recommendations for the creators of new standards.
NaOH Treatment Impact in the Dimensional Stability of Banana Pseudostem Particleboard Panels
Authors: Guimarães Bárbara Maria Ribeiro , Bufalino Lina , Guimarães Jr. José Benedito , Mendes Rafael Farinassi , Mendes Lourival Marin , Tonoli Gustavo H. Denzin
Published: March 2014

This work intends to verify the technical feasibility of NaOH treatment in particleboard manufacture made from banana pseudostem fibers. The particles were treated for a 24 hour period and subsequently washed with water to remove the product. The concentration used was NaOH at 0.5%. The adhesive used was urea - formaldehyde at 12%, the pressing cycle was 4 MPa, at 160 °C for 8 minutes. The water absorption after 2 hours immersion was 148.79% and 189.83% after 24 hours. Thickness swelling value after 2 hours was 54.96% and 74.05% after 24 hours. The results were above the literature values and the minimum values required by the CS 236-66 standard for swelling after 24 hours immersion.
Durability of High Performance Concrete in an Aggressive Environment
Authors: Merida Ahcene , Kharchi Fattoum , Chaid Rabah
Published: March 2014

In Algeria, locally available natural pozzolan of volcanic origin material has the potential for use in environmental friendly concrete as a partial cement replacement. This paper studies the effect of replacement level of pozzolan concrete in sulphated environment. The natural pozzolan has a marked influence on the properties of the concrete. When it is coupled to a water reducing superplasticizer by a correct adjustment of the composition, it greatly improves the concrete properties. The analysis of experimental results on pozzolan concrete at 5% content and fineness of 9565 cm2/g exposed in sulphated environment, show that it positively contributes to the improvement of its mechanical, physical and physico-chemical characteristics. Trough this research work, parameters such as compressive strength development, chloride permeability, water absorption and sulphates resistance are studied.
Mechanical Behavior of Bamboo Species Guadua angustifolia under Compression along the Thickness of the Culm
Authors: Orozco Gustavo , Villegas Laura , García José Jaime
Published: March 2014

The bamboo speciesGuadua angustifoliais a natural functionally graded material with a high potential to help solving the housing deficit in Latin American countries. Bamboo plantations also play an important role to help reducing the devastation of tropical forests. Many studies have demonstrated the excellent mechanical properties of bamboo along the length of the culm. However, other properties like the strength under circumferential tension and shear are low and the associated types of failure are fragile. Therefore, longitudinal fissures are often initiated in the structural joints which avoid taking advantage of the high resistance along the longitudinal direction. To the best of our knowledge, no study has been devoted to study the mechanical behavior of bamboo along the thickness of the culm or radial direction. This characterization may be crucial to improve the performance of the joints in bamboo structures. The aim of this study was to determine the strength and the Young ́s modulus ofGuadua angustifoliaalong the radial direction. Thus, 27 small hexahedral elements of approximately 11mm× 6mm× 7mmwere tested under compression along the thickness of the culm. The stress-strain curves depicted a typical ductile behavior with an average failure strain of 37.8 ± 5.4 %. The failure was characterized by fissures on planes parallel to the fibers and forming angles in the range 35° - 55° with respect to the axis of loading. The secant Young ́s modulus and the radial strength were equal to 44.50 ±9.60MPa, and 18.50 ±4.20MParespectively and there was no significant difference with position along the culm. The initial Young ́s modulus was equal to 96.73 ±52.30MPa, 37.00 ±24.35MPaand 48.90 ±7.31MPafor the bottom, middle and upper portions of the culm and there was a significant difference (p=0.025) between the bottom and middle locations. The high variations of the initial Young ́s modulus may be explained by the irregular form of the surfaces of contact with the testing machine, that were not cut perfectly flat in order to preserve the intact material. These experiments show that Guadua behaves as a ductile material under compression along the thickness of the culm. This property may be used to improve the efficiency of structural joints by applying radial compression.
Main Evaluation Dimensions and Indicators for Non-Conventional Materials and Technologies - NOCMAT R&D Projects
Authors: Ohayon Pierre , Ghavami Khosrow
Published: March 2014

Science and technology have contributed since the Second World War to the economic development without considering adequately different social classes. The intensive Research and Development (R&D) activities in the rapidly growing areas of Science, Technology and Innovation (ST&I) such as new high resistance cements, steel, petrochemical derived materials, among others have not given the opportunity to less developed nations to cut the vicious circle which maintained them technologically dependent on industrialized countries. Also, the results of many successfully realized R&D projects concerned with Non-Conventional Materials and Technologies (NOCMAT) in developing countries including Brazil have not been used in large scale in practice. This is due to the lack of evaluation criteria from planning to project implementation by governmental agencies, private organizations and educational institutions concerned with the newly developed sustainable materials and technologies. The problems of evaluating R&D innovation outputs and impacts for civil construction are complex and need scientific and systematic studies in order to avoid the social and environmental mistakes occurred in industrialized countries. This paper presents four relevant dimensions and its pertinent indicators for NOCMAT projects evaluation concerned with materials, structural elements and technologies of bamboo, soil and composites reinforced with vegetable fibers. Specifically, 1) Political, Strategic and Normative; 2) Organizational; 3) Allocation and Management of Resources; and 4) Technical, Scientific and Economic evaluation dimensions are considered and discussed.
Light Cementitious Composites with Wastes from the Footwear Industry
Authors: Dantas Carolina Pereira , Leal Antônio Farias , Barbosa Normando Perazzo , Torres Sandro Marden
Published: March 2014

Emphasizing the cost reduction and the sustainable development, the construction sector, is more and more, in search of the possibility of the use of non-conventional materials produced with industrial waste or from renewable sources. The large volume of industrial waste constitutes a serious environmental problem. The use of sisal fiber with fiber-cement reinforcement is strategically for the national development, because Brazil is the largest producer and exporter of this fiber. The present study aims to contribute to the viability of the use of SBR waste in the footwear industry and the sisal fiber, in the development of light cementitious composites. The mechanical and physical properties of the composites were evaluated, with cement or plaster matrix, varying the levels of SBR waste incorporation and the production technique, through tests of absorption and flexural strength. The viability of the materials was proved for a possible use in the production of light construction elements, such as plates and panels, for thermal protection of masonry, seeking energy efficiency of buildings.
Performance of Natural Aggregates and Recycled Aggregates for Unbound Granular Pavement Layers
Authors: de Farias Pinto Helen Karla Ramalho , de Assis Sérgio Ricardo Honório , de Melo Ricardo Almeida
Published: March 2014

Recycled aggregates from solid waste can be used on pavements to minimize road construction costs and decrease environmental impacts related to the exploitation of natural resources and pollution. Thus, this study aimed to compare the mechanical performance of mixtures composed of natural aggregates, concrete recycled aggregates and polyethylene terephthalate (PET) flakes (in proportions from 0.5 to 4.0%) for application in granular pavement layers. Asphalt mixing, construction and demolition solid waste recycling, and PET recycling plants located in Joao Pessoa/PB, Brazil, provided the material used in this study. Tests such as particle size distribution, compaction with intermediate energy and California Bearing Ratio (CBR) were performed. The results of particle size distribution were useful to determine particle size proportions according to Brazilian DNIT specified standards and to prepare specimens for CBR tests. The compaction results indicated optimum water contents of 8.0 and 14.9%, and maximum dry densities of 2.01 and 1.83 g/cm3, for natural aggregates and recycled aggregates, respectively. Moreover, the optimum water contents increased between 16.4 and 17.7%, while the maximum dry densities decreased from 1.773 to 1.702 g/cm3 in mixtures of recycled aggregates and PET flakes, as PET proportions rose. Assessing mechanical resistance, the CBR value of natural aggregates resulted 45%, while that of recycled aggregates resulted 61%. On the other hand, the CBR results did not show a particular behavior tendency with the addition of recycled PET flakes. Therefore, it was possible to conclude that concrete recycled aggregates are technically viable for use in building granular pavement layers (sub-base and base) with low traffic flow, in spite of the variability of CBR results for mixtures of recycled aggregates and PET flakes.
A Modular System for Vertical Sealing Panels of Paper Tube
Authors: de Cássia Salado Gerusa , Sichieri Eduvaldo Paulo
Published: March 2014

Problem statement: The society has been worried about the environment, especially due to the intense exploitation of natural resources, the large quantity of residues and their effects on the planet. In this context, the study and development of new materials in civil construction have become fundamental to make use of industrial residues or products discarded by the population. An alternative is to recycle paper and use it to manufacture cardboard tubes to serve as structural elements and sealing in the Architecture and civil construction areas, as Japanese architect Shigeru Ban has made in his projects worldwide for over twenty years. Approach: This paper addresses the elaboration of innovative modular panels made of cardboard tubes for vertical sealing and the construction system developed for their use. The panels underwent several analyses: compression resistance, sandbag impact and steel ball impact, and a test cell was also constructed to test their construction system and structural performance. Results: The panels showed good results in all tests, resisting a maximum of 5000 kgf compression load, besides high elasticity and tenacity in the impact resistance tests. Therefore, both the construction system and its complements have been patented. Conclusions: The panels showed enough resistance to be used in constructions. They offer several advantages to the sector of prefabricated buildings and housing, such as lightness, cleanliness and speed of execution and are a good alternative for some types of constructions, such as temporary, popular, emergency and movable. These panels are of large importance due to their recyclability, contributing towards environmental sustainability.
The Bubble Hall: Bamboo Reticular Geodesic Structure with the Shape of a Soap Bubble
Authors: Correia de Melo João Victor , Ripper Lucas Alves , Ripper José Luiz Mendes , dos Santos Teixeira Filho Walter
Published: March 2014

This article aims to disclose some aspects of the research and constructive methods on lightweight structures made of tied-up bamboos developed by the Laboratory for Investigation in Living Design, LILD, from PUC-Rio. In this paper, we demonstrate the way of obtaining a shape similar to the one of a soap bubble when blown and manipulated by the researcher, according to previously established parameters. The approximation of such a geometry is achieved through a variety of interactive experiments between the states of a model electronic, manufactured /miniature, and in use that follow the logics of geodesic lines, obtained by means of a grid when inflated. Finally, we present results of initial observations of the assemblage of the bamboo reticular structure in the in use state, that we call The Bubble Hall.
The Impact of Mineral Fillers on the Mechanical and the Thermal Properties of Polyester
Authors: Shokry Khaled M.
Published: March 2014

Polyester resins has found a wide spread in many applications. Filler materials are used extensively with polyester resin for a variety of reasons like cost reduction, and more importantly to enhance some physical and/or mechanical properties. Through the present work several types of inorganic fillers (cement, silica fume, and sand) were incorporated into the polyester resin. Their effects on the mechanical and the thermal properties were investigated. Quantitative measurements and qualitative observations were made to recognize the different aspects related to their employment in attempt to find an appropriate means to enhance a prescribed property. Test results revealed that although a pronounced enhancement of the mechanical properties was achieved, but a specific filler type may not has the same effect on each mechanical property. Therefore, in real applications where only some of the properties are of concern, the proper filler type and content should be specified accordingly. Anyhow, employing a combination of filler types (mixed fillers) is an efficient way to utilize the benefits of each of the employed fillers.
Pastes of Plaster with Latex of Euphorbia Tirucalli: Evaluation of Plasticity, Water Absorption, Compressive Strength and Durability
Authors: do Amaral Nogueira Jesus Charles , Bezerra Ulisses Targino , Barbosa Normando Perazzo
Published: March 2014

The aim of this paper is to present the results of the addition of latex of Euphorbia tirucalli, known as Aveloz in improving the properties of fresh plaster pastes with respect to increased plasticity, and to investigate the changes on their hardened state. In the methodology, set tests were performed for compressive strength, water absorption and durability. Two rates were fixed water / gypsum, 40% and 50% water over the mass of gypsum with a percentage point latex addition of between 1% and 5%. The addition of latex showed good results in increasing the resistance to compression, decreasing absorption and increasing the durability of specimens subjected to a jet of water to simulate rainfall of 600 mm /m2.hours at a speed of 10 m/s. In their fresh state, the pastes had enough plasticity to molding with manual compression.
The Effect of Post-Conventional Thermal Annealing Process on the Photoluminescence Characteristics of Si+-Implanted SiO2 Thin Films
Authors: Yang Fann Wei , Cheng Chien Min , Chen Kai Huang
Published: March 2014

The shifted band and high intensity of the photoluminescence characteristics for RTA-treated Si+-implanted SiO2thin films for 400-nm-thick thickness using post-CTA processing were discussed and investigated. The samples were treated in the temperature of 1150°C and 20s RTA processing under dry nitrogen atmosphere. The PL band of thin films obtained was 1.7 eV. However, the PL intensity of thin films was continuous decreased for RTA annealing time increased. In this study, the PL band for RTA-treated thin films using 1h post-CTA processing was shifted from 1.5 to 1.67 eV. In addition, the PL intensity of the thin films was increased under the post-CTA annealing time increased to 60s. From the plan-view of the HRTEM image, the Si nanocrystals of the RTA-treated thin films using post-CTA processing were observed. These results were related to the presence and variation of silicon Si nanocrystals embedded in thin films.
Luminescence Behaviors of the New Upconversion Phosphors of Yb/Ho Co-Doped (Gd1-xLux)3Al5O12 (x=0.1-0.5) Garnet Solid Solutions
Authors: Li Jin Kai , Li Ji Guang , Liu Shao Hong , Li Xiao Dong , Sun Xu Dong , Sakka Yoshio
Published: March 2014

The metastable garnet lattice of Gd3Al5O12(GdAG) was effectively stabilized via doping with significantly smaller Lu3+, and based on which (Gd,Lu)AG:Yb/Ho was developed in this work as a new type of upconversion phosphor. The phosphor particles calcined from the precursors synthesized via carbonate precipitation were observed to have good dispersion and fairly uniform morphologies. Optical spectroscopy found that the [(Gd1-xLux)0.948Yb0.05Ho0.002]3Al5O12(x=0.1-0.5) garnet powders exhibit a green emission centered at ~543 nm (the5F4,5S25I8transition of Ho3+) and a red emission centered at ~668 nm (the5F55I8transition of Ho3+) under laser excitation at 978 nm. The upconversion emission intensity was found to decrease with increasing Lu3+doping. Meanwhile, the dependence of up-conversion emission intensity on the pumping power was measured and the up-conversion mechanism was discussed in detail. The Yb/Ho codoped (Gd,Lu)AG garnet system developed herein may potentially be used as a new type of luminescent material.
Visible-Light-Driven Photocatalytic Performance of Ag@TiO2 Nanocrystals: The Effects of Phases and Morphologies
Authors: Chen Qian Qian , Chen De Liang , Ge Lian Fang , Hou Shao Ke , Zhang Rui
Published: March 2014

Silver decorated TiO2 nanoparticles (Ag@syn-TiO2, Ag@P25) were synthesized by photoreducing Ag+ species in the presence of the synthetized TiO2 (syn-TiO2) nanocrystals or P25. The samples obtained were characterized by XRD, XPS, UV-vis and TEM. The XRD results showed the syn-TiO2 nanoparticles were pure anatase, and the P25 nanoparticles were the mixture of antase and rutile. The TEM observations and XPS spectra indicated that Ag species anchored on the surfaces of syn-TiO2 nanoparticles as Ag0 and AgO nanoclusters (NCs). The Ag NCs have a size range of 13 nm and the AgO NCs have a size range of 1015 nm. The Ag NCs on the surface of P25 have a size range of 57 nm, and no AgO species were found. The photocatalytic performance of the Ag@syn-TiO2 and Ag@P25 samples was evaluated by degradating Rhodamine B (RhB) under visible-light irradiation (λ ≥ 420 nm). The results indicated that the phases and morphologies of TiO2 nanocrystals have effects on their photocatalytic properties, and that the syn-TiO2 nanocrystals wiht the pure anatase are more active than P25 with the mixture of antase and rutile in RhB degradation. The possible mechanisms were discussed.
The Structure and Electrical Conductivity of the CNTs/PMMA Nanocomposites Foams
Authors: Shen Qiang , Yuan Huan , Xiong Yuan Lu , Luo Guo Qiang , Zhang Lian Meng
Published: March 2014

Carbon nanofillers/polymer nanocomposites foam with electrical conductivity was a novel functional material. In this study, the CNTs/PMMA nanocomposites were prepared by the combination of ultrasonic dispersion and anti-solvent precipitation method. Then supercritical foaming method was untilized applied to prepare the foams. The morphology and the electrical conductivity of the foams were investigated. The conductivity of the nanocomposites showed a conductor behavior which was increased t from 1×10-6S/cm to 1×10-5S/cm with the CNTs content range from 1 wt.% to 2.5 wt.%. After foaming, the cell size of the foams was below 10 μm while the cell density increased 2~3 orders of magnitude compared with PMMA foams. The produced CNTs/PMMA nanocomposites foams exhibited a wide range electricity conductivity of the nanofiller contents. Key words: structure, electrical conductivity, CNTs, nanocomposites foams
Effects of CaO Additives on the Phase Evolution of ZrO2-SiC Composites from Zircon by Carbothermal Reduction
Authors: Wu Ze Lin , Fang Ming Hao , Huang Zhao Hui , Liu Yan Gai , Xu You Guo , Wu Xiao Wen , Liu Bao Lin
Published: March 2014

In this study, Ca2+ stabilized ZrO2-SiC composite materials were prepared via carbothermal reduction, using natural zircon ore as raw material, CaO as additive, and black carbon as the reducing agent. The effects of synthesis temperature and CaO content on the phase composition of the products were investigated by XRD. The microstructure and micro-area chemical analysis of the products were characterized by SEM and EDS. The results indicate that: (1) Ca2+ stabilized ZrO2-SiC composite materials could be prepared from natural zircon ore with CaO addition between 1500°C and 1600°C for 4 hours by carbothermal reduction process. (2) The synthetic temperature has an important influence on the phase composition of the carbothermal reduction products of zircon. The production of m-ZrO2 and t-ZrO2 got obviously enhanced with increasing temperature from 1500°C to 1600°C. (3) At the same synthetic temperature, Ca2+ stabilized ZrO2 got enhanced with increasing adding amount of CaO. The optimized synthesis condition of Ca2+ stabilized cubic-ZrO2/SiC composite materials is sintering at 1600°C for 4 hours with adding 40 mol% CaO as additive.
Fabrication and Switching Characterizations of Copper Oxide Thin Films for Applications in Resistive Random Access Memory Devices
Authors: Kuan Min Chang , Yang Fann Wei , Cheng Chien Min , Chen Kai Huang
Published: March 2014

Many nonvolatile memory devices such as, ferroelectric random access memory (FeRAM), magnetic random access memory (MRAM), ovonic universal memory (OUM), and resistive random access memory (RRAM) were considerable discussed and investigated. For these nonvolatile memory devices, the RRAM devices will play an important role because of its non-destructive readout, low operation voltage, high operation speed, long retention time, and simple structure. The RRAM devices were only consist of one resistor and one corresponding transistor. In this study, the CuO thin films deposited on ITO/glass and Pt/Ti/SiO2/Si substrates for applications in RRAM devices were produced and investigated. The optimal sputtering conditions of as-deposited CuO thin films were the rf power of 80 W, chamber pressure of 20 mTorr, substrate temperature of 580°C, and an oxygen concentration of 40%. The basic mechanisms for the bistable resistance switching were observed. The electrical and physics properties of CuO thin films for applications in RRAM devices were discussed.
Synthesis of YAG Powders by Co-Precipitation Method
Authors: Li Yan Juan , Zhang Ying Chun , Leng Jia Xun
Published: March 2014

In this paper, yttrium aluminum garnet (YAG) powders were synthesized by the normal-strike co-precipitation method (adding precipitant solution to the metal nitrate solution). Aluminum nitrate (Al (NO3)39H2O) and yttrium nitrate (Y(NO3)36H2O) were used as raw materials and ammonium hydrogen carbonate (AHC) was used as the precipitant. The precursor was calcined at the temperature of 900-1200 °C for 2 hours. The crystal structure and microstructure of YAG powders were investigated and analyzed by XRD, FESEM, TG-DTA and laser particle size analysis. The results show that the concentration of metal ion and AHC have a significant effect on crystal structure of YAG powders, and pure YAG powders were obtained at 1000 °C when the concentration of Al3+was 0.1 mol/L and the concentration of AHC was 1 mol/L. The average primary crystallites particle sizes were ranged from 50 nm to100 nm in diameter. nanosize YAG powders with excellent properties and good dispersity can be produced at the temperature of 1100 °C.
Microwave Synthesis of Silicon Carbide Nano Powders with Silicon and Carbon
Authors: Lu You Jun , Shen Hong Fang , Guo Sheng Wei
Published: March 2014

Nanosized silicon carbide powders were synthesized from a mixture of silicon and carbon by microwave heating methods. The Result Indicates SiC can be formed at lower temperatures by using the Si-C reaction at 1200°C for 30min. XRD patterns shows that SiC peaks appeared as the only crystalline phase. SEM photo shows the particle size was 100～200 nanometer. At the same time, Effects of chemical reaction of silicon and carbon was researched by mechanical activated microwave synthesis.
Preparation and Characterization of Ultra-Fine ZrB2 by Sol-Gel Method
Authors: Jing Lei , E Lei , Wang En Yuan , Mi Xin Yue
Published: March 2014

Ultra-fine ZrB2 powders were synthesized by sol-gel carbothermal processing using zirconium oxychloride (ZrOCl2.8H2O), boric acid (H3BO3) and sucrose (C12H22O11) as raw materials. Additionally, mannitol was used as cosolvent to obtain a stable high-concentration ZrB2 sol. Since C12H22O11 can be completely decomposed to carbon, carbon might be accounted precisely for the carbothermal reduction reaction. In the case of C/Zr(mol.)=6.0 and B/Zr(mol.)=3.0, a single phase ZrB2 without residual ZrO2 or ZrC was obtained. The photomicrograph revealed a spheres shape morphology with an uniform size distribution.
Combustion Synthesis of Porous Si3N4 Based Ceramics with Glass as Additives
Authors: Li Wen Kui , Chen Fei Yang , Huang Long , Zhuang Han Rui
Published: March 2014

In this paper, porous silicon nitride ceramics were prepared feasibly by combustion synthesis with different glasses as additives. The results reveal that the morphology, strength and porosity are relevant to glass type. When BN is added, the porosity and strength is depended on the glass content. With the increasing glass content, the porosity of the composite decreased and the strength increased.
Combustion Synthesis and Infrared Characterization of TiB2
Authors: Li Su , Li Jun Shou , Zhao Fang , Wang Ming Yuan , Wu Xiao Juan
Published: March 2014

On the basis of magnesiothermy, with Mg powder, TiO2 powder and B2O3 powder as mixed reactants, relatively pure TiB2 powder was prepared by self-propagating high temperature synthesis (SHS) after leached in diluted hydrochloric acid with the suitable concentration. The product after leached was examined by XRD for qualitative and quantitative analysis, SEM for morphology analysis and infrared spectroscopy for transmittance analysis. It was found that diluted hydrochloric acid could decrease most of the impurities, and the proportion of TiB2 phase in the product is more than 99%, which was hexagonal shape crystal with the grain size of 200-300 nm. Compare with the infrared spectrogram of the middle infrared spectral region of the product of before and after acid pickling, it was found that the transmittance of TiB2 is extremely low in the range of 2000-4000 cm-1, which can be excellent infrared absorption material in the corresponding wave band.
Evolution of Composition and Structure of Poly[(alkylamino)borazine] to Boron Nitride Ceramic during Pyrolysis Process
Authors: Deng Cheng , Zhu Meng Fu , Su Hong Bo , You Xiu Dong , Chen Ping
Published: March 2014

Boron nitride (BN) was prepared by polymer-derived method using precursor poly [(alkylamino) borazin (PABZ). The evolution of composition and structure of precursor PABZ into BN ceramic during curing and pyrolysis process was investigated by FTIR, TG, XRD techniques and chemical analysis. The results showed that PABZ could fulfill curing heated at 80°C for 2hrs in NH3 atmosphere. During the curing process the both transamination reaction and condensation reaction occurred, resulting in cross-link between monomer molecular. With the proceeding of curing process, the new B-N bonds were formed and continued to expand in three dimensions. After cured treatment the thermal pyrolysis of PABZ in ammonia atmosphere was took place, and inorganic degree and crystallinity of products were better, which was more suitable for preparation of high purity hexagonal BN (h-BN) ceramic.
Consolidation of Aluminium Oxynitride Powders Using Hydrolysis of Aluminium Nitride
Authors: Bućko Mirosław M. , Domagała Jakub , Lach Radosław
Published: March 2014

One of the materials with high potential for application as a refractory material is aluminum oxynitride with spinel-type structure, γ-alon. Alon materials, single-phase or composites, are characterized by good mechanical properties, high thermal shock resistance and a high corrosion and erosion resistance. Another advantage is possibility of usage of SHS method for producing of relatively good sinterable powders of γ-alon, however, are characterized by poor compressibility. This paper describes a method of compaction of SHS-derived γ-alon powder using the hydrolysis reaction of aluminum nitride, which is one of the products of SHS synthesis. The green bodies made from the powder with addition of 10 mas.% of water after two weeks of storage reach a strength level up to 30 MPa and an open porosity of less than 30%. Pressureless sintering of the such compacts allows to achieve 95% of theoretical density at 1700°C in less than one minute.