bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of Vertical Seismic Isolation of Self-Anchored Cable-Stayed Suspension Bridge Based on Lead Rubber Bearing
Authors: Miao Feng
Published: March 2014

Based on the background of Dalian Bay Cross-Sea Bridge project, some plans with settings of lead-rubber bearing among side pier, tower and stiffening girder have been analyzed under vertical seismic input using the favorable shearing property of laminated rubber, damping characteristics of lead and reasonable parameters (yield force and stiffness). Analysis results show that the displacement of controlling node and force of controlling section have been reduced.
Geometrically Nonlinear Analysis on a Double Controlled Form Finding Method Considering Construction Process of Suspen-Domes
Authors: Liu Hui Juan , Yang Lu Feng , Li Yan Lei , Xu Hua
Published: March 2014

Based on the time-varying suspen-domes model, a configuration-cable force dual control form-finding algorithm was proposed, taking the construction process and construction technology into consideration, according to the looped cable tensioning construction technique, especially in the practical project. The form-finding algorithm was complemented by inverse iteration method for controlling the structure configuration and the initial stress increment method for controlling the cable force. Furthermore, the influence of geometric nonlinearity, construction process, and other construction technology could be taken into consideration.
Characterizing the Influence of Drying on Ink Absorption Using Reconstructed Images by Laser Scanning Confocal Microscopy
Authors: Li Jian Guo , Li Ying
Published: March 2014

The objective of this experiment was to investigate the relationship between drying and ink absorption using laser scanning confocal microscopy (LSCM). Fluorescent ink was used to observe and characterize ink penetration and distribution by LSCM. Three-dimensional images of ink penetration were obtained by reconstructing all XY plane images. Reconstructed images were used to describe ink absorption in coated paper by LSCM. The results implied that it was reliable and effective using LSCM to characterize the ink penetration depth and distribution uniformity. This method could not damage the specimen and did not need fluorescent dye to stain the specimen, which decreased the errors by hand operation. The results indicated that drying temperature affected ink penetration depth and distribution evenness. Higher and lower drying temperature could not contribute to ink absorption uniformity. With the drying temperature increasing, ink penetration depth in coated paper increased.
Influence of Panel Density on the Shear and Peel Property of Sandwich Composites
Authors: Wang Hui Xia , Jia Li Xia , Liu Jun Mei , Liu Yin Yin
Published: March 2014

Three different panel density of sandwich composites were designed. The composite was reinforced by spacer fabric woven with polyester filaments, fiiled by polyurethane foam in the space of the fabric and composite the epoxy resin on the surface of the fabric. The effects of different panel density on the mechanical properties of sandwich composite were tested,including the shear property and peel property. The results showed that the panel density have some effects on the mechanical properties. Shear and peel property increased with the panel density increased.
Preparation and Characterization of PET/MMT Nanocomposition Modified by MDI
Authors: Gu Xiao Hua , Zhang Xi Wei , Xu Bao Yun , Zeng Peng
Published: March 2014

In this paper, the diphenyl methane diisocyanate (MDI) was used to modify montmorillonoid (MMT) and got the organic montmorillonite (OMMT), which was used with the monomers of PET by in situ polymerization method to prepare PET/MMT nanocomposition. The OMMT was analyzed by the X ray diffraction (XRD) to test the change of the spacing layer. Dispersion of MMT in the PET/MMT nanocomposites were studied with XRD and SEM and by means of thermogravimetric analyzer (TGA) on the thermal stability of PET/MMT nanocomposites. The results showed that, MDI modified MMT successfully, and the compatibility of MMT and PET was increased .
Study of Forward Osmosis Membrane Bioreactor
Authors: Wang Le Jun , Wang Wei , Qu Rui , Qi Teng Teng , Zhang Yu Feng , Cheng Bo Wen
Published: March 2014

A novel submerged forward osmosis membrane bioreactor (FOMBR) is presented in this study. The selection of optical draw solutions for forward osmosis (FO) applications was developed and the Na2SO4 solution was found to be the most appropriate draw solution among five draw solutions for FO applications. The properties of two hollow fiber composite FO membranes, designated membranes A and B, which consist of an active layer formed atop a support layer, were prepared and utilized. Meanwhile, the water flux and removal efficiencies were evaluated in FO mode. Both of the FO membranes were found to reject greater than 95% of COD and 85% of NH3-N. Water flux changes suggested a better application with membrane A than membrane B for FOMBR.
The Relationship of High Strength Aluminum Alloy Corrosion Behavior and Corrosion Environment
Authors: Zhou Song , Hui Li , Xu Liang , Guo Yu Tong , Ma Shao Hua
Published: March 2014

The aim of this article is to research the characteristics of corrosion pit on 2xxx aluminum alloys in different environments (3.5wt% NaCl solution, water in fuel tank and wet air). Measure the area of corrosion pit, the depth of corrosion pit in different environments. The results show that in 3.5wt% NaCl solution: the initiation of surface corrosion pits mainly occur in 24h, with time increasing ,the depth of corrosion pit rises indistinctively; in water in fuel tank : during 24h-120h, with the extension of corrosion time, the maximum depth of corrosion pits changed a little, the maximum corrosion area became a little smaller than that in 3.5wt% NaCl solution; in wet air: the corrosion damage was smaller than that in 3.5wt% NaCl solution and water in fuel tank, the depth of the corrosion pit was about 20μm, the biggest size of corrosion pit area was about 0.5 x104μm2.
Low Cycle Fatigue Behavior of Q345b Steel under Uniaxial Cycle Loading
Authors: You Xiang , Wang Rui Dong , Cui Shi Ming , Liu Yong Jie , Wang Qingyuan
Published: March 2014

In this paper, the low cycle fatigue (LCF) behavior of Q345b steel was experimentally investigated in fully reversed cyclic axial configurations at room temperature. The strain range of 0.3%, 0.4%, 0.5%, 0.6% and 0.7% at constant strain rate of 0.005 s-1 was adopted. Cyclic stress-strain curve and strain life relationship were analyzed according to the Ramberg-Osgood relationship and Coffin-Manson relationship respectively. Suitable parameters were obtained showing good agreements with the experimental fatigue data.
Evaluation of Mechanical Properties of Adobe Chemically Stabilized with "Synthetic Termite Saliva"
Authors: Corrêa Andréa A.R. , Bufalino Lina , de Paula Protásio Thiago , Ribeiro Marcelo X. , Wisky Danilo , Mendes Lourival Marin
Published: March 2014

The raw mud brick (adobe) is a millenary technology that awakens a wide interest in ecologic and non-conventional constructions. Some advantages are low cost, thermal comfort and minimum environmental impact. For better use, it is important to improve their mechanical properties. Dynasolo DS-328®is a chemical stabilizer used in soil compression for road paving and it is similar to termite saliva. This composition is based on vegetal oils. It is a high-concentrated liquid product, water soluble, non-toxic, non-corrosive, and non-flammable. The cohesive properties promote the investigation about the incorporation of this product in adobe composition. Therefore, this work aimed to evaluate synthetic termite saliva" incorporation to adobes at four different concentrations: 1:2000; 1:1500; 1:1000 and 1:500. The reagent is an aluminum sulfate at 1:5000 for all treatments. The soil is a Red Latosol cambisol corrected to 50% fine sand fraction. Soil bulk density, particle density and total pore volume were: Ds = 1.42 kg/dm3, Dp = 2.62 kg/dm3 and VTP = 45.8%. The soil Atterberg limits were: LL (liquid limit) 55.44%; PL (plastic limit) 34.58%; SL (shrinkage limit) 21.67%; and PI (plasticity index) 20.86%. The ideal moisture content was variable, ranging from 50% to 40% according synthetic termite saliva" increase. Adobes were submitted to compression and bending resistance tests. This research confirmed that synthetic termite saliva" incorporation improved the adobe compressive resistance and chose the treatment 1:1500 because it increased 20% this property.
Fabric Reinforcement for Improved Toughness of Adobe Block Wall Systems
Authors: Böttger Hana Mori , Ostertag Claudia
Published: March 2014

This paper investigates an inexpensive but potentially very effective reinforcement method for adobe block wall systems. Reinforcing fabric materials were embedded in the mortar between each layer of blocks to provide a barrier against the propagation of the dominant diagonal cracks which are commonly observed in adobe walls after a seismic event, and are largely responsible for the collapse of adobe structures. The effectiveness of the reinforcing materials in resisting and arresting cracks was investigated in splitting tension tests. Reinforced and unreinforced adobe walls were fabricated and tested in diagonal compression to simulate the transfer of shear due to lateral forces. Felt fabric reinforcement was found to provide the greatest physical deformation of the wall sample and greatest dissipation of energy while maintaining acceptable load-bearing capacity. The final displacement of the reinforced sample was found to be nearly three times that of the unreinforced control specimen. A secondary motivation for this investigation was to address the need for such engineering solutions to be highly affordable to those most likely to build with adobe block. Earthquakes have ravaged many regions of the world, and while advancements in engineering and life-safety codes have resulted in significant improvements in performance of modern structures, we must also seek out methods by which traditional building systems, which continue to house large numbers of people, can withstand the scrutiny of modern safety criteria. Further investigations are encouraged to determine location-specific solutions with this goal in mind.
Environmental Savings Potential from the Use of Bahareque (Mortar Cement Plastered Bamboo) in Switzerland
Authors: Zea Escamilla Edwin , Habert Guillaume , Lopez Muñoz Luis Felipe
Published: March 2014

The urgency for energy and material efficiency in the building sector increases every day. In the case of Switzerland, a buildings main energy demand occurs during its use/operation phase and is mainly related to heating demands during the winter season. As a means of reducing these demands, current building practice in Switzerland is to insulate with 30cm of foam and to mechanically control indoor environments. Recent research has shown, however, that alternatives to current practice are readily available. With these alternative techniques, natural materials with low embodied energy are used to produce high efficiency building envelopes. The bahareque construction method (bamboo plastered with mortar cement) studied in this paper has been identified as a promising technology both in terms of producing energy efficient building envelopes and also with regards to reducing the environmental impact associated with the construction of buildings in Switzerland. The main objective of the research presented here was to identify the Environmental Savings Potential (ESP) of bahareque in comparison with state of the art technologies in Switzerland. The calculations were geographically limited to Switzerland and the main data sets used for the life cycle assessment models corresponded to this region. Specific datasets were developed for bamboo and bahareque to account for transoceanic transportation. The results showed that bahareque achieves an ESP of 32% compared with clay brick construction and 40% when compared with concrete block construction. It was shown that it is feasible to develop highly efficient building envelopes with low embodied energy that can be used within the Swiss context.
Effect of High Temperature on Properties of Bricks Using Granulated Blast-Furnace Slag as Aggregate Replacement
Authors: El Nouhy Hanan A.
Published: March 2014

This research investigates the influence of high temperature on the properties of bricks containing non-ground granulated blast-furnace slag (GBFS) as fine aggregate replacement. Replacement percentages were 0%, 25% and 50% by dry weight of fine aggregates. The manufactured bricks were exposed to 200°С, 400°С, 600°С, and 800°С for a constant duration of two hours after 28 days of curing. Tests were conducted according to both Egyptian Standard Specifications (ESS) and American Society for Testing and Materials (ASTM) in order to determine compressive strength, absorption percentage, oven-dry weight, and ultrasound pulse velocity. Also, loss in weight was performed. Compressive strength limit regarding load-bearing units was met by mix 1 at all tested temperatures. Mixes 2 and 3, resulted in compressive strength that satisfied the requirement for load-bearing units at temperatures ranging from room temperature to 600°С.Compressive strength obtained regarding mixes 2 and 3 met the requirements of non-load bearing units at 800°С. The control mix resulted in normal weight bricks when tested at the various temperatures till 600°С. At 800°С, mixes 2 and 3 yielded light weight and medium weight bricks, respectively. There was a significant reduction in mass when comparing the mass at 800°С with the corresponding mass at room temperature concerning the three mixes. Results showed that it is feasible to partially replace fine aggregate with GBFS even when bricks are subjected to elevated temperature.
Effect of Milling Process for Rice Husk Ash on Mechanical Strength of Blended Portland Cement Mortars
Authors: da Silva Everton Jose , Marques Maria Lidiane , Vasconcelos Antonio Rogério B. , Akasaki Jorge L. , Tashima Mauro M. , Pereira Adriana M.
Published: March 2014

Nowadays, the reuse of waste products in the construction process is a priority research area. Several industrial and agricultural waste products have been investigated, such as fly ash, sugar cane bagasse ash and rice husk ash. This paper analyzes a very important aspect under intense discussion in the scientific community: the Rice Husk Ash (RHA) grinding process. This paper investigates a low carbon RHA with high pozzolanic reactivity produced under uncontrolled burning conditions. The compressive strength of mortar specimens prepared using both ground and natural RHA were tested for 3-56 days and the capillarity absorption was measured for mortars cured during 28 days. Very promising and interesting results were obtained using natural rice husk ash in the production of blended mortars.
Inclusion of Lignocellulosic Fibers in Plastic Composites
Authors: de Almeida Mesquita Ricardo Gabriel , Tonoli Gustavo H. Denzin , Mendes Rafael Farinassi , da Silva César Antônia Amanda , Bufalino Lina , Mendes Lourival Marin
Published: March 2014

Solutions for the production of sustainable plastics have motivated the scientific community to search for new alternatives for the replacement of raw materials from non-renewable sources such as glass fibers. Therefore, plant fibers appear to be a feasible alternative, since they present low cost, suitable mechanical strength, wide availability, as well as are renewable. This work aimed to evaluate the replacement of glass fibers by lignocellulosic fiber in plastic composites used in civil construction sectors. The resin used was ortho unsaturated polyester. Three plant fibers were tested (sugar cane bagasse, eucalypt and pine) with and without chemical modification. The chemical modifications were performed with sodium hydroxide. The composites were evaluated by their physical and mechanical properties. The initial results showed the potential of using plant fiber in the production of fiber-reinforced plastic composites. Keywords: plant fibers, residues, polyester resin
Numerical-Experimental Assessment of the Arumã Fiber as Reinforcement to the Cementitious Matrix
Authors: Gorett dos Santos Marques Maria , de Almeida Melo Filho João , Molina Julio Cesar , Toledo Filho Romildo Dias , de Vasconcelos Raimundo Pereira , Calil Junior Carlito
Published: March 2014

Composites of high mechanical performance reinforced by fibers need a well set arrangement of them in the matrix so that under reinforcement which they can be submitted, a desirable performance can be shown. Thus, the cement composite studied has a cement matrix which received a reinforcement made by arumã fibers, shaped in bidirectional frames distributed in three layers. Arumã is a typical plant from the Amazon, species from the genus Ischnosiphon polyphyllus, part of the family Marantaceae. This study had the purpose of assessing the cement composites mechanical behaviour from the bending tests in four points and puncture tests in sheets which were supported by the four edges. Having presented mechanical results, a numerical simulation was made through the SAP2000 NonLinear® software, with the aim to obtain a numerical computational model able to represent the composites behaviour up to the point where the loading reaches the greatest amount. The numerical results present a good correlation with those obtained in the experimental tests.
The Influence of Fiber Treatment on the Mechanical Behavior of Jute Textile Reinforced Concrete
Authors: Fidelis Maria Ernestina Alves , de Andrade Silva Flávio , Toledo Filho Romildo Dias
Published: March 2014

In the present work a natural textile reinforced concrete (TRC) was developed and mechanically characterized. A fabric made of jute, a natural occurring fiber, was used as reinforcement in a fine grained cementitious matrix with a low content of calcium hydroxide. Tensile tests were performed on TRC reinforced with 3 and 5 layers of jute fabric. The mechanical tensile tests were coupled with image analysis in order to measure the crack spacing and the results were correlated with the applied tensile strain. Various stages of loading corresponding to initiation, propagation, distribution, opening, and localization of a crack system in the specimen are discussed. In order to improve the fiber-matrix interface the jute fabric was treated with a polymer based coating.
The Influence of Blast Furnace Slag Content on Durability of High Performance Concrete
Authors: Talah Aissa , Kharchi F.
Published: March 2014

This paper reports an experimental study of the influence of finely ground-granulated blast-furnace slag (GGBS) used as partial substitute for Portland cement (PC) on the mechanical properties and durability of high performance concretes. The analysis of the experimental results on concrete at 17.5% content of blast furnace slag with a fineness modulus of 8500 cm2/g, in a chloride environment, showed that it contributes positively to the perfection of its mechanical characteristics, its durability with respect to water absorption and migration of chloride ions. On the basis of the experiments performed, it can be concluded that the GGBS is suitable for formulation of high performance concretes (HPC) and their properties are significantly better compared to the reference concrete (RC).
Experimental Study of Concrete Class Influence on Cracks Spacing
Authors: Zorkane Omar , Chalah Farid , Chalah-Rezgui Lila , Bali Abderrahim , Oudjit Mohamed Nadib
Published: March 2014

The aim of this work is to study the cracking of reinforced concrete continuous beams by considering different classes of concrete.
It is well known that the design of reinforced concrete structures includes three limit states (limit state of collapse, limit state of strain and limit state of cracking). The cracks in reinforced concrete structures are admitted in the phase II (cracked sections). Thus, the phenomenon of cracks formation can be treated as a normal state only when their openings are limited to avoid a permanent risk of collapse and ensure durability for the civil engineering concrete structures.
The importance of this work is described by the tests made on reinforced concrete continuous beams in real size, under concentrated loads increasing from zero up to collapse, where the concrete class influence on the cracks spacing has been studied. As this wasnt theoretically investigated, the used references for an aim comparison were relative to experimentations made by Monnier and Kuczynski on an only one concrete class to the cracks openings and the spacing evaluation analysis The findings of the research reported in this paper show that there is no effect of the concrete class on the cracks spacing.
Tensile and Flexural Strength of Untreated Woven Henequen-Glass Fabric Reinforced Epoxy Hybrid Composites
Authors: de Jesús Ángel Marroquín , Olivares Ramírez Juan Manuel , Reyes-Araiza José Luis , Manzano-Ramirez Alejandro , Apatiga Castro Luis Miguel , Eleazar Urbina A. , Ramirez Jimenez Ruben , Arroyo Contreras Moises
Published: March 2014

The use of eco-friendly composites has gained attraction due to its lightweight and moderate strength in recent years. The aim of this paper was to study the influence of the stacking sequence of glass and henequen fabrics on the mechanical properties of epoxy composites. Fiber/Matrix interface adhesion was examined using SEM. It was observed how the tensile and flexural properties of the hybrid reinforced epoxy laminates with henequen and glass fabrics, increase as the number of layers of henequen woven fabric decrease while stacking sequence does not have a great effect on the tensile properties. However, when ten layers of henequen fabric were used, a eco-friendly composite material with good mechanical strength was obtained due to the mechanical anchoring of the henequen fabric with the epoxy resin. Hence, it is clearly shown how by tailoring the geometry of the fabric, improvements in the mechanical properties of eco-friendly polymer composites can be achieved.
Surface Topographical Characterization of Concrete Protected by Coal Tar Using 3D Profilometry
Authors: Couto Ribeiro Carmen , da Silva Pinto Joana Darc , de Godoy Cristina Durães , Bamberg Paula , Starling Tadeu
Published: March 2014

The results obtained for the characterization of the surface texture of concrete protected by coal tar using a 3D-topographical approach are presented here. The concrete, which presents a low waterbinder ratio, high compressive strength, and high impermeability, has been subjected to an aggressive acidic environment by immersion in 2.5%H2SO4. The profilometry technique, which produces 3D-topographical images and amplitude parameters, is used to compare the coated and uncoated surface textures before and after chemical attack, to evaluate the degradation of concrete, and the minimization of such effect in the coated concrete. The degradation and the minimization of degradation can be confirmed by the variation in all the parameters studied. This research, based on studies of profilometric analyses, demonstrates the accuracy, precision and efficiency of this technique in analyzing the concrete surface, indicating that it can be broadly employed in concrete durability research. The methodology adopted demonstrates that the application of coal tar as a protective coating for concrete in an aggressive environment minimizes its surface degradation and increases its durability.
Preliminary Studies on the use of Sugar Cane Bagasse Ash (SCBA) in the Manufacture of Alkali Activated Binders
Authors: Castaldelli Vinicius N. , Tashima Mauro M. , Melges José Luiz P. , Akasaki Jorge L. , Monzó J.M. , Borrachero M.V. , Soriano Lourdes , Payá J.
Published: March 2014

Alkali activated binders require the addition of a mineral-rich amorphous silica and alumina. This paper proposes the use of a mineral residue from the burning of sugar cane bagasse. The alkali activated mixtures were prepared containing binary mixtures of sugar cane bagasse ash (SCBA) and other mineral admixtures: fly ash (FA) or blast furnace slag (BFS). As alkaline activators, mixtures of alkali (Na+ or K+) hydroxide and alkali (Na+ or K+) silicate were used. Alkali-activated pastes and mortars containing binary systems SCBA/FA or SCBA/BFS were prepared and cured at 65 oC. Microstructural properties of these alternative binders were assessed by means of TGA, SEM, XRD and pH measurements. Mechanical strength of mortars was performed after 3 and 7 days at 65 oC. Compressive mechanical strengths of these mortars were in the range 30-55 MPa, showing the good mechanical performance achieved by the alkali activation. Microstructural studies suggested the development of stable matrices and the formation of typical gel.
Use of Coffee Plant Stem in the Production of Conventional Particleboards
Authors: da Silva César Antônia Amanda , Bufalino Lina , de Macedo Laurenn Borges , de Almeida Mesquita Ricardo Gabriel , de Paula Protásio Thiago , Mendes Lourival Marin
Published: March 2014

When the productivity of a coffee plantation drops considerably, the crop must be renewed. In this case, the removed plants become residues to be discarded. This work aimed to verify the utilization of the coffee plant stem in the production of conventional particleboards. The basic density and chemical composition of the coffee stem was obtained. 3 particleboards were produced with urea-formaldehyde at 6% and paraffin at 1%. The target density of the panels was 0.600 g/cm3. The pressing cycle used was: pressure of 0.32 MPa, temperature of 160°C and time of 8 minutes. Apparent density (AD), water absorption (WA), thickness swelling (TS) after 2 and 24 hours immersion and thickness non-return rate (TNRR) were the physical properties obtained. Mechanical properties evaluated were parallel compression (CP), static bending (MOE and MOR) and internal bonding (IB). The average basic density, total extractive, lignin, mineral components and holocelluloses contents obtained were 0.581gcm-3, 11%, 28%, 2% and 59%, respectively. The average values of the physical and mechanical properties of the boards, followed by their standard deviation were: AD= 0.577 gcm-3 (0.018); CR = 1.03 (0.12); WA_2h = 55% (2.3); WA_24r = 76% (2.5); TS_2h = 32% (4.4); TS_24h = 59% (7.8); TNRR = 62 % (2.0); IB = 0.43 MPa (0.03); CP = 4.9 MPa (0.23); MOE = 1324.4 MPa (1.02); and MOR = 13.4 MPa (1.02). Coffee stem conventional particleboards presented poor physical resistance. On the other hand, they may be commercialized for general uses in dry-conditions.
Spent FCC Catalyst for Preparing Alkali-Activated Binders: An Opportunity for a High-Degree Valorization
Authors: Tashima Mauro M. , Soriano Lourdes , Akasaki Jorge L. , Castaldelli Vinicius N. , Monzó J.M. , Payá J. , Borrachero M.V.
Published: March 2014

Spent FCC catalyst is a waste from the petrochemical industry which has excellent pozzolanic properties, containing more than 90% silica and alumina. Its similarity to metakaolin creates interesting prospects for its use in the production of alkali-activated binders. In this study, the alkali activation of this residue, spent FCC catalyst, through mixtures with alkali hydroxide and silicate solutions (both sodium and potassium) has been carried out. The alkali cation had an important role in the nature of AA-FCC pastes: some differences in the mass loss in the thermogravimetric tests and in the X-ray mineral characterization were found. No significant differences in compressive strength were observed for mortars cured for 3 days in several conditions: room temperature and 65oC. Prepared AA-FCC mortars had a compressive strength of about 65-70 MPa. Microstructural studies showed that an amorphous, dense and compact microstructure was obtained, independent of the activating solution and curing condition.
Architect Werner Schmidt's Straw-Bale Construction
Authors: Bocco Guarneri Andrea
Published: March 2014

Werner Schmidt (Trübbach, Switzerland, 1953) is one of the most interesting contemporary 'green' architects, particularly experienced in straw-bale building. His accomplishments include now 20 straw-bale buildings of which 14 at least partially load-bearing. This paper extracts some essential principles from his work and explains in detail his technological solutions. This is the result of a thorough analysis, carried on during the preparation of a monograph. The success of his approach derives from many factors, among which: - Schmidt's training as a mason. In contrast with many fellow architects, his designs are rooted in practicality and feasibility. Moreover, he actively participates to the construction work. - His holistic vision of ecological building: straw bales are chosen because of the overall advantages they offer. Preferably, he adopts a modified 'Nebraska' technique, using high-density 'jumbo bales' forming more than 120 cm thick walls. This rather unique method assures rapidity of construction, and allows to solve a number of criticalities associated with 'small bale' building. - Not seeking the highest possible performances lets to focus economic and technical efforts on few elements that really need to be state-of-the-art. The envelope can be built with simple techniques, while parts that need be built precisely (stairs, cooking implements, baths, etc.) can be prefabricated. Schmidt's work shows that high ecological consideration can be coupled with convincing architectural results. The quality of his buildings in terms of energy performance, living value, and beautiful form constitutes a good practice promoting new ways to 'green' architecture.
Sustainable School-Village
Authors: Sá Ribeiro Marilene Gomes , Sá Ribeiro Ruy Alexandre
Published: March 2014

To inhibit the degradation of the forest reserves it is necessary to stimulate the consciousness and involvement of the surrounding communities. This work would be more effective with a program of ecological consciousness applied within an environment where people can learn by practicing. For this purpose, we envisage the creation of a Sustainable Building Program (SBP) to build ecological school-villages surrounding the forest reserves subjected to constant aggressions. This is the case of the Adolpho Ducke Forest Reserve whose vulnerability has increased due to Manaus urban expansion. As the worlds largest urban forest fragment, it demands protection of its borders. It is suggested to implement the SBP to build ecological school-villages as a protection belt to preserve the forest integrity and its natural water fountains. It may also attract eco tourism and serve as a prototype sustainable eco barrier. The school-villages shall shelter people enrolled in social residential programs who will learn by practicing environment education and green building techniques. Storage and selective collection of recyclables shall be emphasized. The organic residues generated by the village shall be used to feed biogas tanks to support the kitchen of the Community Center (CC). The CC shall host the theoretical classes. This program shall also shelter victims from natural disasters, families relocated from risky areas, and low-income families from the rural areas coming to the capital for health treatment by the state. The SBP envisage two-pavement villages comprised of green roof, and green materials such as bamboo, clay from site excavations, wood and bamboo residues, and hydrated lime of carburet. The villages shall comprise rain water catchment and utilization, ecological sewage treatment, and green roof supported by a structural bamboo ceiling. The structural bamboo shall be of the species Guadua angustifolia. The apartments shall comprise bamboo based modular wall panels. Wall panel structures, columns, and beams are prefabricated with bamboo-based structures and cemented with micro concrete. This way, the bamboo used as a non-conventional construction material shall substitute the wood partially, or totally, reducing the pressure on logging.
Mathematical Aspects Regarding Cracks Behaviour in Wood Composites
Authors: Craciun Eduard Marius , Sadowski Tomasz , Marsavina Liviu , Rabaea Adrian
Published: March 2014

In this paper we study the interaction of two unequal collinear cracks in a pre-stressed fiber reinforced wood composite material in anti-plane mode of fracture. A mathematical model is associated to the mechanical problem. Starting from the boundary, constitutive and far field conditions we obtain the representation of the incremental displacement, stress and strain fields using two complex potentials. Using Sih s generalized fracture criterion we determine the critical incremental shear stress which produce crack propagation and the crack tips propagation direction in a particular case of a Pine wood composite.
Stress Analysis of Hyperbaric Chambers of Different Geometries
Authors: Petronić Sanja , Tatić Uroš , Sedmak Simon , Djeric Aleksandra , Komnenic Zara
Published: March 2014

Hyperbaric Oxygen Therapy (HBOT) is a method used to administer pure oxygen at a pressure which is greater than atmospheric pressure in order to increase the concentration of O2 in the tissues, blood and cells, and correct or improve certain conditions. The hyperbaric chamber is a medical instrument that provides many benefits to the economy and health protection. They are in fact pressure vessels, subjected to the higher stress levels. In this paper, the stress and deformation state of different multiplace hyperbaric chambers are determined. Stress and deformation states are calculated for different geometry models using ABAQUS. Therefore, the aim of this paper is to define the weakest points in the chambers of different geometry with the use of the Finite Element Method.
Cyclic Loading of Polyetheretherketone at High Tensile Stress Levels
Authors: Berer Michael , Major Zoltan , Pinter Gerald , Constantinescu Dan Mihai , Marsavina Liviu
Published: March 2014

In a recent study of the corresponding author, it was found that PEEK bearing elements revealed high (irreversible) surface strains if they were loaded between steel sheets. Since this reflects the conditions in the practical application and because the rolling properties are dominated by the surface material, a more detailed analysis of highly strained PEEK was required. Hence, fatigue tests in the high stress tensile regime were conducted. The experiments were carried out on servo-hydraulic testing machines and during the tests the mechanical response of the specimens was recorded. Two material modifications of PEEK were investigated in the research: untreated PEEK (without heat treatment) and annealed PEEK which was modified using defined thermal conditions. The analysis of the recorded test data aimed on the distinction between cumulative material response (creep deformation, material hardening / softening) and spontaneous material response (material hardening / softening). At the highest stress levels, the cumulative response pretended material softening with increasing number of cycles. However, by examining the spontaneous material response which became stiffer with increasing number of cycles, it was shown that the cumulative softening was caused by time-dependent deformation processes.
Stress and Displacements Analysis for Drilling Mast Elements Made of Rectangular Pipe: The Overload Test Case
Authors: Popa Ioan , Stanciu Lavinia Silvia
Published: March 2014

In the oil and gas industry, the drilling masts are complex metallic constructions made of welded ends beams, which can be classified, from a mechanical point of view, in the statically indeterminate structures` category. The drilling mast is a part of the hoisting system of a drilling rig and its main purposes are: to support some devices as the crown block at the top, the crane, the rotary swivel etc and to provide support for the drill pipes to be stacked vertically during the round trips operations, which implies the operation of removing the drill string from the wellbore or running it back in the hole.
Study of Multiple Holes Influence on Theoretical Stress Concentration Coefficient in Case of Cylindrical Vessels
Authors: Faur Nicolae , Galatanu Sergiu Valentin , Hluscu Mihai
Published: March 2014

In the construction of pressure vessels, especially for steam boilers used in power plants, cylindrical vessels are commonly used. For this important class of mechanical structures, through holes also frequently cause stress concentration which must be taken into account in the design and estimation of their lifetime. In the scientific literature which addresses stress concentration effects for such structures are studied in cases of which the presence of through holes is singular. This paper studies the effect of stress concentration in case of two or more holes placed at a small distance between them, according to construction requirements. In these cases the simplifying assumption of Saint Venant according to which at sufficient distance from the analyzed area the state of stress is not influenced by how the load is applied cannot be accepted. In this paper we study the stress concentration coefficient with numerical methods using the finite element method and more precisely, ABAQUS software package, version 6.9. Different constructive cases of multiple holes are studied: two and three successive holes with the same diameter and different diameters placed on the generating line with variable distance, for which the ratio between the diameter and the distance between the holes varies. Numerical model validation was done by comparing the results obtained for specific computational models in case of which results are known and presented in the literature [1,2]. Based on the results, variation curves of the theoretical stress concentration coefficient were drawn for all cases listed above.
Synthesis and Analysis of the Bellows Actuators
Authors: Jişa Vasile Sergiu , Mândru Dan
Published: March 2014

Bellows generally operate as pressure transducers, based on elastic deformation of their undulations, but presents a higher interest as actuators. After a short presentation of the actuators based on elastic / inflatable elements, some structural schemes of bellows - based actuating systems are given, FEM analysis is emphasized and initial prototypes are described.
Correlation between Numerical and Experimental Analysis Using Model Updating Techniques
Authors: Rosu Paul-Virgil , Mihaila Mihai , Canarache Radu , Dascotte Eddy
Published: March 2014

With the increasing complexity of the products, engineers face a higher level of uncertainty in both simulation and test. Correlation between numerical and experimental analysis using model updating techniques helps engineers to asses uncertainty. Present research efforts focus to combine finite element analysis and testing in one common framework. Experimental and operational modal analysis and simulation make benefit from common databases. Some applications presented emphasize the advantages of these techniques.
Ocular Thermography: Investigation on some Pathologies
Authors: Corvi Andrea , Matteoli Sara
Published: March 2014

The focus of this research is the investigation of the Ocular Surface Temperature (OST) in both healthy and pathological (e.g. age-related macular degeneration, eye dry syndrome and choroidal lesions) eyes by using Infrared Thermography (IR). Specifically, the temperature of different anatomical areas (or points) of the eye is measured by applying image processing procedures on the infrared images recorded. It is known that the pathogenesis of some ocular pathology is related to the variation of ocular blood perfusion, and thus to the temperatures of the anterior segment of the eye. Results demonstrated that thermography can provide quantitative documentation of these temperature measurements. Furthermore, thermography is a non-invasive, cheap, harmless and portable technique. The challenge is to make ocular thermography part of the daily diagnostic procedure by providing more and more reliable experimental data.
Modeling and Finite Element Analysis of the Human Knee Joint Affected by Osteoarthritis
Authors: Tarniţă Daniela , Catana Marius , Tarnita Dan Nicolae
Published: March 2014

The paper presents a complex three-dimensional model of the human knee joint, containing bones, ligaments, menisci, tibial and femoral cartilages. To investigate the role of the articular cartilage in the developing of the osteoarthritis, to analyze and simulate the biomechanical behavior of the human knee joint, a finite element analysis was performed. The non-linearities are due to the presence of the contact elements modeled between components surfaces and to the nonlinear properties of the cartilage, applying a load of 800 N and 1500 N, for 0o in flexion. The results show that misalignment (valgus variation) could damage the articular cartilage because they increase the stress magnitude, that progressively produce articular cartilage damage and it enhances the osteoarthritis phenomenon due to mechanical factors. The displacements and the Von Mises stress distributions on the cartilage and menisci for the virtual prototype, considering an angle of 10 degrees for valgus, are presented. The obtained values are comparable with the values obtained by other authors.
Calculation of Maximum Tensile and Shear Forces in Restorative Materials Using Finite Element Method
Authors: Milosevic Milos , Tatić Uroš , Sedmak Simon , Perović Jasmina , Miletić Vesna
Published: March 2014

The purpose of this paper was to determine tensile loading that leads to dental restoration failure, i.e. the critical values of stress. In order to analyze stress distribution within the restoration and tooth, mechanical properties of materials and tissues, such as Young modulus and Poissons ratio were taken into account. An additional purpose of the paper was to determine whether tensile or shear stresses that occur in the restorative composite and the surrounding enamel cause this failure. Tensile stress is caused by forces acting in the direction perpendicular to the cross-section of a given element, whereas shear stresses are caused by forces parallel to said cross section. A 3D numerical model of a tooth including three different materials (dentine, enamel and composite) was made and used for these calculations. These results will be used as a base for the physical experiment.
Evaluation of Rearfoot Deformity Based on Instrumented Motion Analysis. Talus Valgus Case Study
Authors: Stoia Dan Ioan , Toth-Taşcău Mirela , Vigaru Cosmina , Pasca Oana
Published: March 2014

The paper proposes a first level protocol (FLP) that can be used in investigation of the gait movement. This protocol is composed of six major stages, each one being considered as a second level protocol. In the paper, beside the FLP, the protocol for data processing is presented. This second level protocol can be used only for kinematic data of the gait. In order to prove the utility of the data processing protocol, this was applied to the data recorded for two children. The first one was considered as reference and the other one was diagnosed with Talus Valgus. The results of the subjects were graphically represented in two ways: by computing the averages on each subject only, and by averaging, applying the angular corrections and normalizing the time series. Therefore, the paper presents both a global and data processing protocol (a branch of the first one), and their concrete application on the recordings of the ankle joint variables, in gait analysis.
Influence of Acetabular Liner Design on Periprosthetic Pressures during Daily Activities
Authors: Krepelka Mircea , Toth-Taşcău Mirela
Published: March 2014

In this study, periacetabular pressures produced by different acetabular liner geometries were analyzed using Finite Element Method. The cup models consist of hemispherical metal shells fitted with normal and different chamfered polyethylene liner geometries, with the same degree of femoral head coverage. The aim of this study was to understand the influence of the design parameters of the chamfered liners, which are primarily designed to increase the range of motion (ROM) of the hip joint and reduce the risk of impingement, on the acetabular contact pressures. The cup models were loaded to simulate periacetabular pressures during routine activities. The proposed models have been analyzed considering a cup position of 40o lateral abduction and 15o anteversion. The results show that the difference in contact pressure between the normal and chamfer models was not substantial in the given orientation of the cup. Also, the increase of the chamfer angle has a small influence on the maximum contact pressures, although that could be also dependent on the reduction of the polyethylene thickness. Pre-clinical testing of total hip prostheses using Finite Element Method enables the evaluation of contact pressures and stress distribution, and proves to be a valuable tool to analyze the parameters reducing the contact pressure.
Influence of the Sampling Rate on the Measurements of the Upper Limb Movements
Authors: Toth-Taşcău Mirela , Stoia Dan Ioan , Bălănean Flavia
Published: March 2014

The main objective of the study consists in determination of the most appropriate sampling rate of the measurements in instrumented kinematic analysis of the upper limb movements. The measuring system involved in the study is Zebris CMS-HS Measuring System, whose configuration was defined by ultrasound markers attached to specific body sites. The sampling rate interval was set from 10 to 25 Hz, according to the system’s range of frequencies. The kinematic parameters which have been analyzed are shoulder and elbow flexion-extension and shoulder abduction-adduction. A comparative kinematical analysis of the angle variations of flexion-extension and abduction-adduction in shoulder joint and flexion-extension in elbow joint was performed for both left and right upper limbs at each sampling rate.
Clinical Outcomes after Chevron Procedure are Better than Pedobarographic Results
Authors: Prejbeanu Radu , Vermesan Dinu , Hărăgus Horia , Vermesan Simona , Stoia Dan Ioan
Published: March 2014

The distal Chevron or Austin procedure, is arguably the most prominent of the distal metatarsal osteotomies. Recent studies in the literature have shown a trend in recommending this osteotomy or one if it’s modifications for even severe hallux valgus deformities. Therefore we aimed to compare the clinical and pedobarographic results after chevron osteotomy in patients with moderate hallux valgus deformity. We investigated a homogeneous lot of 10 patients undergoing hallux valgus correction using distal chevron technique. In order to quantify the improvement of the gait in these patients, several biomechanical parameters have been measured using a matrix of pressure sensors that provide us the vertical reaction forces when the foot is in physical contact with it. Results show an improvement in patient’s velocity and cadence after the surgery, and also a smaller variability in gait. Nevertheless, optimal clinical outcomes are still found to have altered ground reaction forces on pedobarographic assessment.
First Metatarsophalangeal Arthrodesis Modifies Plantar Pressures Distribution
Authors: Vermesan Dinu , Prejbeanu Radu , Hărăgus Horia , Toth-Taşcău Mirela , Stoia Dan Ioan
Published: March 2014

First MTF (metatarsophalangeal) arthrodesis is a frequent procedure for hallux rigidus (first MTF arthrosis) or hallux valgus (bunion) in the presence of arthrosis. We present the clinical benefits and foot biomechanics after first MTF arthrodesis for revision hallux valgus surgery. For this purpose we included patients which had previous hallux valgus surgery and MTF arthrodesis for correction of recurrent deformity and pain. We measured static and dynamic pressures (ground reaction forces - GRF) using pedobarographic and gait measurements over long term follow-up. We found good and functional gait patterns and GRF distributions which showed somewhat normal persistent plantar pressures at 2 years after first MTF arthrodesis. In cases of infection this procedure proved also to be a cure for the local sepsis. The procedure allows good kinematics and mobility even in young patients and compensatory increased mobility of the interphalangeal joint and proximal first ray were observed.