Non-Uniform Compressive Strength of Debonded Sandwich Panels
DEFF Research Database (Denmark)
Nøkkentved, Alexandros; Lundsgaard-Larsen, Christian; Berggreen, Carl Christian
2005-01-01
debonds show a considerable strength reduction with increasing debond diameter, with failure mechanisms varying between fast debond propagation and wrinkling-introduced face compression failure for large and small debonds, respectively. Residual strength predictions are based on intact panel testing...
Non-Uniform Compressive Strength of Debonded Sandwich Panels
DEFF Research Database (Denmark)
Berggreen, Carl Christian; Simonsen, Bo Cerup
2005-01-01
.(2005)., shows that the model is indeed able to predict the failure modes and the residual strength of damaged panels with accuracy sufficient for practical applications. This opens up for a number of important engineering applications, for example risk-based inspection and repair schemes....
Guo, Anxin; Yuan, Wenting; Li, Haitao; Li, Hui
2018-04-01
In the aggressive marine environment over a long-term service period, coastal bridges inevitably sustain corrosion-induced damage due to high sea salt and humidity. This paper investigates the strength reduction of coastal bridges, especially focusing on the effects of non-uniform corrosion along the height of bridge piers. First, the corrosion initiation time and the degradation of reinforcement and concrete are analyzed for bridge piers in marine environments. To investigate the various damage modes of the concrete cover, a discretization method with fiber cells is used for calculating time-dependent interaction diagrams of cross-sections of the bridge piers at the atmospheric zone and the splash and tidal zone under a combination of axial force and bending moment. Second, the shear strength of these aging structures is analyzed. Numerical simulation indicates that the strength of a concrete pier experiences dramatic reduction from corrosion initiation to the spalling of the concrete cover. Strength loss in the splash and tidal zone is more significant than in the atmospheric zone when structures' service time is assumed to be the same.
Investigation of non-uniform airflow signal oscillation during high frequency chest compression
Directory of Open Access Journals (Sweden)
Lee Jongwon
2005-05-01
Full Text Available Abstract Background High frequency chest compression (HFCC is a useful and popular therapy for clearing bronchial airways of excessive or thicker mucus. Our observation of respiratory airflow of a subject during use of HFCC showed the airflow oscillation by HFCC was strongly influenced by the nonlinearity of the respiratory system. We used a computational model-based approach to analyse the respiratory airflow during use of HFCC. Methods The computational model, which is based on previous physiological studies and represented by an electrical circuit analogue, was used for simulation of in vivo protocol that shows the nonlinearity of the respiratory system. Besides, airflow was measured during use of HFCC. We compared the simulation results to either the measured data or the previous research, to understand and explain the observations. Results and discussion We could observe two important phenomena during respiration pertaining to the airflow signal oscillation generated by HFCC. The amplitudes of HFCC airflow signals varied depending on spontaneous airflow signals. We used the simulation results to investigate how the nonlinearity of airway resistance, lung capacitance, and inertance of air characterized the respiratory airflow. The simulation results indicated that lung capacitance or the inertance of air is also not a factor in the non-uniformity of HFCC airflow signals. Although not perfect, our circuit analogue model allows us to effectively simulate the nonlinear characteristics of the respiratory system. Conclusion We found that the amplitudes of HFCC airflow signals behave as a function of spontaneous airflow signals. This is due to the nonlinearity of the respiratory system, particularly variations in airway resistance.
Anisotropic Concrete Compressive Strength
DEFF Research Database (Denmark)
Gustenhoff Hansen, Søren; Jørgensen, Henrik Brøner; Hoang, Linh Cao
2017-01-01
When the load carrying capacity of existing concrete structures is (re-)assessed it is often based on compressive strength of cores drilled out from the structure. Existing studies show that the core compressive strength is anisotropic; i.e. it depends on whether the cores are drilled parallel...
Directory of Open Access Journals (Sweden)
Buscaglia Gustavo C.
2001-01-01
Full Text Available A new numerical approach is proposed to alleviate the computational cost of solving non-linear non-uniform homogenized problems. The article details the application of the proposed approach to lubrication problems with roughness effects. The method is based on a two-parameter Taylor expansion of the implicit dependence of the homogenized coefficients on the average pressure and on the local value of the air gap thickness. A fourth-order Taylor expansion provides an approximation that is accurate enough to be used in the global problem solution instead of the exact dependence, without introducing significant errors. In this way, when solving the global problem, the solution of local problems is simply replaced by the evaluation of a polynomial. Moreover, the method leads naturally to Newton-Raphson nonlinear iterations, that further reduce the cost. The overall efficiency of the numerical methodology makes it feasible to apply rigorous homogenization techniques in the analysis of compressible fluid contact considering roughness effects. Previous work makes use of an heuristic averaging technique. Numerical comparison proves that homogenization-based methods are superior when the roughness is strongly anisotropic and not aligned with the flow direction.
Directory of Open Access Journals (Sweden)
Kupavtsev Vladimir Vladimirovich
2014-02-01
Full Text Available The method of two-sided evaluations is extended to the problems of stability of an elastic non-uniformly compressed rod, the variation formulations of which may be presented in terms of internal bending moments with uniform integral conditions. The problems are considered, in which one rod end is fixed and the other rod end is either restraint or pivoted, or embedded into a support which may be shifted in a transversal direction.For the substantiation of the lower evaluations determination, a sequence of functionals is constructed, the minimum values of which are the lower evaluations for the minimum critical value of the loading parameter of the rod, and the calculation process is reduced to the determination of the maximum eigenvalues of modular matrices. The matrix elements are expressed in terms of integrals of basic functions depending on the type of fixation of the rod ends. The basic functions, with the accuracy up to a linear polynomial, are the same as the bending moments arising with the bifurcation of the equilibrium of a rod with a constant cross-section compressed by longitudinal forces at the rod ends. The calculation of the upper evaluation is reduced to the determination of the maximum eigenvalue of the matrix, which almost coincides with one of the elements of the modular matrices. It is noted that the obtained upper bound evaluation is not worse thanthe evaluation obtained by the Ritz method with the use of the same basic functions.
Relationship between the edgewise compression strength of ...
African Journals Online (AJOL)
The results of this study were used to determine the linear regression constants in the Maltenfort model by correlating the measured board edgewise compression strength (ECT) with the predicted strength, using the paper components' compression strengths, measured with the short-span compression test (SCT) and the ...
optimizing compressive strength characteristics of hollow building
African Journals Online (AJOL)
eobe
Keywords: hollow building Blocks, granite dust, sand, partial replacement, compressive strength. 1. INTRODUCTION ... exposed to extreme climate. The physical ... Sridharan et al [13] conducted shear strength studies on soil-quarry dust.
International Nuclear Information System (INIS)
Kulikov, I.S.; Tverkovkin, B.E.
1984-01-01
The technique and the PRORT mathematical program in FORTRAN language for determining mechanical properties of a fuel element with motionless fuel-cladding interaction taking into account circular temperature non-uniformity in gas-cooled fast reactor conditions are proposed. The calculation results of the fuel element of dissociating gas cooled fast reactor are presented for seven cross-sections over the height of the core. The obtained data testify to appreciable swelling of Cr16Ni15Mo3Nb steel fuel cladding in the conditions of dissociating gas cooled fast reactor through the allowance for the effect of stresses on this essential parameter shows, that its value is lower in comparison with swelling, wherein stresses are not taken into account
Compressive and flexural strength of high strength phase change mortar
Qiao, Qingyao; Fang, Changle
2018-04-01
High-strength cement produces a lot of hydration heat when hydrated, it will usually lead to thermal cracks. Phase change materials (PCM) are very potential thermal storage materials. Utilize PCM can help reduce the hydration heat. Research shows that apply suitable amount of PCM has a significant effect on improving the compressive strength of cement mortar, and can also improve the flexural strength to some extent.
Compressive strength of thick composite panels
DEFF Research Database (Denmark)
Branner, Kim; Berring, Peter
2011-01-01
The aim of this study is to investigate how much the compressive strength of thick composite panels is reduced due to delaminations and to investigate under which conditions a delamination will grow. Understanding of this is essential in order to move forward the design limits used in the structu......The aim of this study is to investigate how much the compressive strength of thick composite panels is reduced due to delaminations and to investigate under which conditions a delamination will grow. Understanding of this is essential in order to move forward the design limits used...
Compressive strength improvement for recycled concrete aggregate
Directory of Open Access Journals (Sweden)
Mohammed Dhiyaa
2018-01-01
Full Text Available Increasing amount of construction waste and, concrete remnants, in particular pose a serious problem. Concrete waste exist in large amounts, do not decay and need long time for disintegration. Therefore, in this work old demolished concrete is crashed and recycled to produce recycled concrete aggregate which can be reused in new concrete production. The effect of using recycled aggregate on concrete compressive strength has been experimentally investigated; silica fume admixture also is used to improve recycled concrete aggregate compressive strength. The main parameters in this study are recycled aggregate and silica fume admixture. The percent of recycled aggregate ranged from (0-100 %. While the silica fume ranged from (0-10 %. The experimental results show that the average concrete compressive strength decreases from 30.85 MPa to 17.58 MPa when the recycled aggregate percentage increased from 0% to 100%. While, when silica fume is used the concrete compressive strength increase again to 29.2 MPa for samples with 100% of recycled aggregate.
Relationship between pore structure and compressive strength
Indian Academy of Sciences (India)
Properties of concrete are strongly dependent on its pore structure features, porosity being an important one among them. This study deals with developing an understanding of the pore structure-compressive strength relationship in concrete. Several concrete mixtures with different pore structures are proportioned and ...
OPTIMISATION OF COMPRESSIVE STRENGTH OF PERIWINKLE ...
African Journals Online (AJOL)
In this paper, a regression model is developed to predict and optimise the compressive strength of periwinkle shell aggregate concrete using Scheffe's regression theory. The results obtained from the derived regression model agreed favourably with the experimental data. The model was tested for adequacy using a student ...
Neu, C P; Hull, M L
2003-04-01
Recent magnetic resonance imaging (MRI) techniques have shown potential for measuring non-uniform deformations throughout the volume (i.e. three-dimensional (3D) deformations) in small orthopedic tissues such as articular cartilage. However, to analyze cartilage deformation using MRI techniques, a system is required which can construct images from multiple acquisitions of MRI signals from the cartilage in both the underformed and deformed states. The objectives of the work reported in this article were to 1) design an apparatus that could apply highly repeatable cyclic compressive loads of 400 N and operate in the bore of an MRI scanner, 2) demonstrate that the apparatus and MRI scanner can be successfully integrated to observe 3D deformations in a phantom material, 3) use the apparatus to determine the load cycle necessary to achieve a steady-state deformation response in normal bovine articular cartilage samples using a flat-surfaced and nonporous indentor in unconfined compression. Composed of electronic and pneumatic components, the apparatus regulated pressure to a double-acting pneumatic cylinder so that (1) load-controlled compression cycles were applied to cartilage samples immersed in a saline bath, (2) loading and recovery periods within a cycle varied in time duration, and (3) load magnitude varied so that the stress applied to cartilage samples was within typical physiological ranges. In addition the apparatus allowed gating for MR image acquisition, and operation within the bore of an MRI scanner without creating image artifacts. The apparatus demonstrated high repeatability in load application with a standard deviation of 1.8% of the mean 400 N load applied. When the apparatus was integrated with an MRI scanner programmed with appropriate pulse sequences, images of a phantom material in both the underformed and deformed states were constructed by assembling data acquired through multiple signal acquisitions. Additionally, the number of cycles to reach
Zhang, L.; Han, X. X.; Ge, J.; Wang, C. H.
2018-01-01
To determine the relationship between compressive strength and flexural strength of pavement geopolymer grouting material, 20 groups of geopolymer grouting materials were prepared, the compressive strength and flexural strength were determined by mechanical properties test. On the basis of excluding the abnormal values through boxplot, the results show that, the compressive strength test results were normal, but there were two mild outliers in 7days flexural strength test. The compressive strength and flexural strength were linearly fitted by SPSS, six regression models were obtained by linear fitting of compressive strength and flexural strength. The linear relationship between compressive strength and flexural strength can be better expressed by the cubic curve model, and the correlation coefficient was 0.842.
Strength and compressibility of returned lunar soil.
Carrier, W. D., III; Bromwell, L. G.; Martin, R. T.
1972-01-01
Two oedometer and three direct shear tests have been performed in vacuum on a 200 g sample of lunar soil from Apollo 12 (12001, 119). The compressibility data have been used to calculate bulk density and shear wave velocity versus depth on the lunar surface. The shear wave velocity was found to increase approximately with the one-fourth power of the depth, and the results suggest that the Apollo 14 Active Seismic Experiment may not have detected the Fra Mauro formation at a depth of 8.5 m, but only naturally consolidated lunar soil. The shear data indicate that the strength of the lunar soil sample is about 65% that of a ground basalt simulant at the same void ratio.
mathematical model for the optimization of compressive strength
African Journals Online (AJOL)
ES Obe
cement and sand either wholly or partially without adverse effect on the strength properties of the ... sandcrete block, compressive strength, laterite, scheffe's theory. 1. Introduction ... that for the properties of a q-component mix- ture which ...
Axial Compressive Strength of Foamcrete with Different Profiles and Dimensions
Directory of Open Access Journals (Sweden)
Othuman Mydin M.A.
2014-01-01
Full Text Available Lightweight foamcrete is a versatile material; primarily consist of a cement based mortar mixed with at least 20% volume of air. High flow ability, lower self-weight, minimal requirement of aggregate, controlled low strength and good thermal insulation properties are a few characteristics of foamcrete. Its dry densities, typically, is below 1600kg/m3 with compressive strengths maximum of 15MPa. The ASTM standard provision specifies a correction factor for concrete strengths of between 14 and 42MPa to compensate for the reduced strength when the aspect height-to-diameter ratio of specimen is less than 2.0, while the CEB-FIP provision specifically mentions the ratio of 150 x 300mm cylinder strength to 150 mm cube strength. However, both provisions requirements do not specifically clarify the applicability and/or modification of the correction factors for the compressive strength of foamcrete. This proposed laboratory work is intended to study the effect of different dimensions and profiles on the axial compressive strength of concrete. Specimens of various dimensions and profiles are cast with square and circular cross-sections i.e., cubes, prisms and cylinders, and to investigate their behavior in compression strength at 7 and 28 days. Hypothetically, compressive strength will decrease with the increase of concrete specimen dimension and concrete specimen with cube profile would yield comparable compressive strength to cylinder (100 x 100 x 100mm cube to 100dia x 200mm cylinder.
Experimental study on compressive strength of sediment brick masonry
Woen, Ean Lee; Malek, Marlinda Abdul; Mohammed, Bashar S.; Chao-Wei, Tang; Tamunif, Muhammad Thaqif
2018-02-01
The effects of pre-wetted unit bricks, mortar type and slenderness ratio of prisms on the compressive strength and failure mode of newly developed sediment brick have been evaluated and compared to clay brick and cement-sand bricks. The results show that pre-wetted sediment brick masonry exhibits higher compressive strength of up to 20% compared to the dry sediment masonry. Using cement-lime mortar leads to lower compressive strength compared to cement mortar. However, the sediment brick masonry with the cement lime mortar exhibit higher compressive strength in comparison with cement mortar masonry. More of diagonal shear cracks have been observed in the failure mode of the sediment bricks masonry compared to clay and cement-sand bricks masonry that show mostly vertical cracks and crushing. The sediment unit bricks display compressive strength in between clay and cement-sand bricks.
Compressive Strength of Compacted Clay-Sand Mixes
Directory of Open Access Journals (Sweden)
Faseel Suleman Khan
2014-01-01
Full Text Available The use of sand to improve the strength of natural clays provides a viable alternative for civil infrastructure construction involving earthwork. The main objective of this note was to investigate the compressive strength of compacted clay-sand mixes. A natural clay of high plasticity was mixed with 20% and 40% sand (SP and their compaction and strength properties were determined. Results indicated that the investigated materials exhibited a brittle behaviour on the dry side of optimum and a ductile behaviour on the wet side of optimum. For each material, the compressive strength increased with an increase in density following a power law function. Conversely, the compressive strength increased with decreasing water content of the material following a similar function. Finally, the compressive strength decreased with an increase in sand content because of increased material heterogeneity and loss of sand grains from the sides during shearing.
Screening of Low Clinker Binders, Compressive Strength and Chloride Ingress
DEFF Research Database (Denmark)
Geiker, Mette Rica; De Weerdt, Klaartje; Garzón, Sergio Ferreiro
2017-01-01
This paper reports an initial screening of potential new binders for concrete with reduced CO2-emission. Mortars cured saturated for 90 days are compared with regard to a) compressive strength of mortars with similar water-to-binder ratio, and b) chloride ingress in similar design strength mortar...... compromising the 90 days compressive strength and resistance to chloride ingress in marine exposure by using selected alternative binders....
Strength properties of interlocking compressed earth brick units
Saari, S.; Bakar, B. H. Abu; Surip, N. A.
2017-10-01
This study presents a laboratory investigation on the properties of interlocking compressed earth brick (ICEB) units. Compressive strength, which is one of the most important properties in masonry structures, is used to determine masonry performance. The compressive strength of the ICEB units was determined by applying a compressive strength test for 340 units from four types of ICEB. To analyze the strength of the ICEB units, each unit was capped by a steel plate at the top and bottom to create a flat surface, and then ICEB was loaded until failure. The average compressive strength of the corresponding ICEB units are as follows: wall brick, 19.15 N/mm2; beam brick, 16.99 N/mm2; column brick, 13.18 N/mm2; and half brick, 11.79 N/mm2. All the ICEB units had compressive strength of over 5 N/mm2, which is the minimum strength for a load-bearing brick. This study proves that ICEB units may be used as load-bearing bricks. The strength of ICEBs is equal to that of other common bricks and blocks that are currently available in the market.
Quasiparticles in non-uniformly magnetized plasma
International Nuclear Information System (INIS)
Sosenko, P.P.
1994-01-01
A quasiparticle concept is generalized for the case of non-uniformly magnetized plasma. Exact and reduced continuity equations for the microscopic density in the quasiparticle phase space are derived, and the nature of quasiparticles is analyzed. The theory is developed for the general case of relativistic particles in electromagnetic fields, besides non-uniform but stationary magnetic fields. Effects of non-stationary magnetic fields are briefly investigated also. 26 refs
STOCHASTIC MODELING OF COMPRESSIVE STRENGTH OF PHOSPHORUS SLAG CONTENT CEMENT
Directory of Open Access Journals (Sweden)
Ali Allahverdi
2016-07-01
Full Text Available One of the common methods for quick determination of compressive strength as one of the most important properties for assessment of cement quality is to apply various modeling approaches. This study is aimed at finding a model for estimating the compressive strength of phosphorus slag content cements. For this purpose, the compressive strengths of chemically activated high phosphorus slag content cement prepared from phosphorus slag (80 wt.%, Portland cement (14 wt.% and a compound chemical activator containing sodium sulfate and anhydrite (6 wt.% were measured at various Blaine finenesses and curing times. Based on the obtained results, a primary stochastic model in terms of curing time and Blaine fineness has been developed. Then, another different dataset was used to incorporate composition variable including weight fractions of phosphorus slag, cement, and activator in the model. This model can be effectively used to predict the compressive strength of phosphorus slag content cements at various Blaine finenesses, curing times, and compositions.
Relationship between pore structure and compressive strength of ...
Indian Academy of Sciences (India)
J BU
compressive strength relationship in ... He applied this equation to experimental data on gypsum plasters and ... Popovics [15] observes that this is true even for different types of ... proportions and curing ages of concrete samples are listed in table 1.
models for predicting compressive strength and water absorption
African Journals Online (AJOL)
user
presents a mathematical model for predicting the compressive strength and water absorption of laterite-quarry dust cement block using ... building and construction of new infrastructure and .... In (6), R is a vector containing the real ratios of the.
Compressive Strength of Longitudinally Stiffened GRP Panels
DEFF Research Database (Denmark)
Böhme, J.; Noury, P.; Riber, Hans Jørgen
1996-01-01
A structural analysis of a cross stiffened orthotropic GRP panel subjected to uniaxial compressive loads is carried out. Analytical solutions to the buckling of such structures are proposed and validated by a finite element analysis. Both analytical and finite element approaches confirm an identi...
Predicting the Compressive Strength of Concretes Made with ...
African Journals Online (AJOL)
In most of these cases the cause of the collapse could be traced to the strength of the construction materials, mainly concrete. Secondly, experimental ... The compressive strength predictions were compared with predictions from an alternative model based on regression analysis. The results of the study show that for the ...
predicting the compressive strength of concretes made with granite
African Journals Online (AJOL)
2013-03-01
Mar 1, 2013 ... computational model based on artificial neural networks for the determination of the compressive strength of concrete ... Strength being the most important property of con- ... to cut corners use low quality concrete materials in .... manner of operation of natural neurons in the human body. ... the output ai.
Forecasting the compressive strength of soil-concretedepending on ...
African Journals Online (AJOL)
One of the most important physical and mechanical properties of soil-concrete is the compressive strength. To this end we carried out a study of soil-concrete strength depending on its curing conditions and percentage of cement. For our study we used loam soil with the plasticity index of Ip = 12.3, Portland cement of type I, ...
Characterization of the Compressive Strength of Sandcrete Blocks in ...
African Journals Online (AJOL)
On the basis of the noted poor quality control, recommendations appropriate for improving the strength and effectiveness of sandcrete blocks production in Nigeria are made. Keywords: Sandcrete Blocks, Compressive Strength, Mix Ratio Journal of Civil Engineering Research and Practice Vol. 5 (1) 2008: pp. 15-28 ...
Hodge, Andrew J.; Nettles, Alan T.; Jackson, Justin R.
2011-01-01
Notched (open hole) composite laminates were tested in compression. The effect on strength of various sizes of through holes was examined. Results were compared to the average stress criterion model. Additionally, laminated sandwich structures were damaged from low-velocity impact with various impact energy levels and different impactor geometries. The compression strength relative to damage size was compared to the notched compression result strength. Open-hole compression strength was found to provide a reasonable bound on compression after impact.
Compression strength perpendicular to grain of structural timber and glulam
DEFF Research Database (Denmark)
Damkilde, Lars; Hoffmeyer, Preben; Pedersen, Torben N.
1998-01-01
The characteristic strength values for compression perpendicular to grain as they appear in EN 338 (structural timber) and EN 1194 (glulam) are currently up for discussion. The present paper provides experimental results based on EN 1193 that may assist in the correct assignment of such strength...... values. The dominant failure mode of glulam specimens is shown to be fundamentally different from that of structural timber specimens. Glulam specimens often show tension perpendicular to grain failure before the compression strength value is reached. Such failure mode is not seen for structural timber....... Nonetheless test results show that the levels of characteristic compression strength perpendicular to grain are of the same order for structural timber and glulam. The values are slightly lower than those appearing in EN 1194 and less than half of those appearing in EN 338. The paper presents a numerical...
Effect of Hand Mixing on the Compressive Strength of Concrete
Directory of Open Access Journals (Sweden)
James Isiwu AGUWA
2010-12-01
Full Text Available This paper presents the effect of hand mixing on the compressive strength of concrete. Before designing the concrete mix, sieve analysis of sharp sand and chippings was carried out and their fineness moduli were determined. Also the dry weight of chippings and the specific gravities of both sand and chippings were determined. A designed concrete mix of 1:2:4 was used and the number of turnings of the mixture over from one end to another by hand mixing was varying from one time up to and including seven times. The strengths were measured at the curing ages of 7, 14, 21 and 28 days respectively using 150mm concrete cubes cast, cured and crushed. The results revealed that the compressive strengths of concrete cubes appreciably increased with increase in number of turnings from one to four times but remained almost constant beyond four times of turning for all the ages tested. For example, at 1, 2, and 3 times turning; the compressive strengths at 28 days were 4.67, 13.37 and 20.28N/mm2 respectively while at 4, 5 and 6 times turning; the compressive strengths at 28 days were 21.15, 21.34 and 21.69N/mm2. From the data, adequate strengths were not developed at turnings below three times of hand mixing, concluding that a minimum of three times turning is required to produce concrete with satisfactory strength.
Shafiq, Nasir; Fadhilnuruddin, Muhd; Elshekh, Ali Elheber Ahmed; Fathi, Ahmed
2015-07-01
Ultrasonic pulse velocity (UPV), is considered as the most important test for non-destructive techniques that are used to evaluate the mechanical characteristics of high strength concrete (HSC). The relationship between the compressive strength of HSC containing chopped basalt fibre stands (CBSF) and UPV was investigated. The concrete specimens were prepared using a different ratio of CBSF as internal strengthening materials. The compressive strength measurements were conducted at the sample ages of 3, 7, 28, 56 and 90 days; whilst, the ultrasonic pulse velocity was measured at 28 days. The result of HSC's compressive strength with the chopped basalt fibre did not show any improvement; instead, it was decreased. The UPV of the chopped basalt fibre reinforced concrete has been found to be less than that of the control mix for each addition ratio of the basalt fibre. A relationship plot is gained between the cube compressive strength for HSC and UPV with various amounts of chopped basalt fibres.
Compressive strength of brick masonry made with weak mortars
DEFF Research Database (Denmark)
Pedersen, Erik Steen; Hansen, Klavs Feilberg
2013-01-01
in the joint will ensure a certain level of load-carrying capacity. This is due to the interaction between compression in the weak mortar and tension in the adjacent bricks. This paper proposes an expression for the compressive strength of masonry made with weak lime mortars (fm... of masonry depends only on the strength of the bricks. A compression failure in masonry made with weak mortars occurs as a tension failure in the bricks, as they seek to prevent the mortar from being pressed out of the joints. The expression is derived by assuming hydrostatic pressure in the mortar joints......, which is the most unfavourable stress distribution with respect to tensile stresses in bricks. The expression is compared with the results of compression tests of masonry made with weak mortars. It can take into account bricks with arbitrary dimensions as well as perforated bricks. For a stronger mortar...
Compressive strength of concrete and mortar containing fly ash
Liskowitz, John W.; Wecharatana, Methi; Jaturapitakkul, Chai; Cerkanowicz, deceased, Anthony E.
1997-01-01
The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction. The invention includes a method for predicting the compressive strength of such a hardenable mixture, which is very important for planning a project. The invention also relates to hardenable mixtures comprising cement and fly ash which can achieve greater compressive strength than hardenable mixtures containing only concrete over the time period relevant for construction. In a specific embodiment, a formula is provided that accurately predicts compressive strength of concrete containing fly ash out to 180 days. In other specific examples, concrete and mortar containing about 15% to 25% fly ash as a replacement for cement, which are capable of meeting design specifications required for building and highway construction, are provided. Such materials can thus significantly reduce construction costs.
Workability and Compressive Strength for Concrete With Coconut Shell Aggregate
Directory of Open Access Journals (Sweden)
Leman Alif Syazani
2017-01-01
Full Text Available This study was conducted to investigate the compressive strength and workability of concrete added with coconut shells. Comparisons were made between conventional concrete with concrete mix coconut shell. In this study, the concretes were mixes with coconut shell by percentage of weight concrete which is 0%, 5%, and 10%. The coconut shell has been crushed first, then it was sieved, to get the optimum size which, that retained on the 5mm sieve and passing 10mm sieve. Experimental tests conducted in this study are slump test and compressive test. The results from this study are workability of concrete added with 0% and 5% of coconut shell has medium degree of workability compared to concrete added with 10% that has low workability. For the compressive strength, the concrete added with 5% and 10% of coconut shell has lower strength compared with normal concrete.
Research on the compressive strength of a passenger vehicle roof
Zhao, Guanglei; Cao, Jianxiao; Liu, Tao; Yang, Na; Zhao, Hongguang
2017-05-01
To study the compressive strength of a passenger vehicle roof, this paper makes the simulation test on the static collapse of the passenger vehicle roof and analyzes the stress and deformation of the vehicle roof under pressure in accordance with the Roof Crush Resistance of Passenger Cars (GB26134-2010). It studies the optimization on the major stressed parts, pillar A, pillar B and the rail of roof, during the static collapse process of passenger vehicle roof. The result shows that the thickness of pillar A and the roof rail has significant influence on the compressive strength of the roof while that of pillar B has minor influence on the compressive strength of the roof.
Effect of Compaction on Compressive Strength of Unfired Clay Blocks
International Nuclear Information System (INIS)
Lakho, N.A.; Zardari, M.A.; Pathan, A.A.
2016-01-01
This study investigates the possible use of unfired compacted clay blocks as a substitute of CSEB (Compressed Stabilized Earth Blocks) for the construction of economical houses. Cubes of 150 mm size were cut from the clay blocks which were compacted at various intensities of pressure during the casting. The results show that the compressive strength of the clay cubes increased with the compacting pressure to which the blocks were subjected during casting. The average crushing strength of the cubes, sawed from clay blocks that were subjected to compacting pressure of 7.2 MPa, was found to be 4.4 MPa. This value of compressive strength is about 50 percent more than that of normal CSEB. This study shows that the compacted clay blocks could be used as economical walling material as replacement of CSEB. (author)
Fracture Energy of High-Strength Concrete in Compression
DEFF Research Database (Denmark)
Dahl, Henrik; Brincker, Rune
is essential for understanding the fracture mechanism of concrete in compression. In this paper a series of tests is reported, carried out for the purpose of studying the fracture mechanical properties of concrete in compression. Including the measurement and study of the descending branch, a new experimental...... method has been used to investigate the influence of boundary conditions, loading rate, size effects and the influence of the strength on the fracture energy of high-strength concrete over the range 70 MPa to 150 MPa, expressed in nominal values....
Relationship between the Compressive and Tensile Strength of Recycled Concrete
International Nuclear Information System (INIS)
El Dalati, R.; Haddad, S.; Matar, P.; Chehade, F.H
2011-01-01
Concrete recycling consists of crushing the concrete provided by demolishing the old constructions, and of using the resulted small pieces as aggregates in the new concrete compositions. The resulted aggregates are called recycled aggregates and the new mix of concrete containing a percentage of recycled aggregates is called recycled concrete. Our previous researches have indicated the optimal percentages of recycled aggregates to be used for different cases of recycled concrete related to the original aggregates nature. All results have shown that the concrete compressive strength is significantly reduced when using recycled aggregates. In order to obtain realistic values of compressive strength, some tests have been carried out by adding water-reducer plasticizer and a specified additional quantity of cement. The results have shown that for a limited range of plasticizer percentage, and a fixed value of additional cement, the compressive strength has reached reasonable value. This paper treats of the effect of using recycled aggregates on the tensile strength of concrete, where concrete results from the special composition defined by our previous work. The aim is to determine the relationship between the compressive and tensile strength of recycled concrete. (author)
Optimum concrete compression strength using bio-enzyme
Bagio Tony Hartono; Basoeki Makno; Tistogondo Julistyana; Pradana Sofyan Ali
2017-01-01
To make concrete with high compressive strength and has a certain concrete specifications other than the main concrete materials are also needed concrete mix quality control and other added material is also in line with the current technology of concrete mix that produces concrete with specific characteristics. Addition of bio enzyme on five concrete mixture that will be compared with normal concrete in order to know the optimum level bio-enzyme in concrete to increase the strength of the con...
Testing compression strength of wood logs by drilling resistance
Kalny, Gerda; Rados, Kristijan; Rauch, Hans Peter
2017-04-01
Soil bioengineering is a construction technique using biological components for hydraulic and civil engineering solutions, based on the application of living plants and other auxiliary materials including among others log wood. Considering the reliability of the construction it is important to know about the durability and the degradation process of the wooden logs to estimate and retain the integral performance of a soil bioengineering system. An important performance indicator is the compression strength, but this parameter is not easy to examine by non-destructive methods. The Rinntech Resistograph is an instrument to measure the drilling resistance by a 3 mm wide needle in a wooden log. It is a quasi-non-destructive method as the remaining hole has no weakening effects to the wood. This is an easy procedure but result in values, hard to interpret. To assign drilling resistance values to specific compression strengths, wooden specimens were tested in an experiment and analysed with the Resistograph. Afterwards compression tests were done at the same specimens. This should allow an easier interpretation of drilling resistance curves in future. For detailed analyses specimens were investigated by means of branch inclusions, cracks and distances between annual rings. Wood specimens are tested perpendicular to the grain. First results show a correlation between drilling resistance and compression strength by using the mean drilling resistance, average width of the annual rings and the mean range of the minima and maxima values as factors for the drilling resistance. The extended limit of proportionality, the offset yield strength and the maximum strength were taken as parameters for compression strength. Further investigations at a second point in time strengthen these results.
Non-uniform tube representation of proteins
DEFF Research Database (Denmark)
Hansen, Mikael Sonne
Treating the full protein structure is often neither computationally nor physically possible. Instead one is forced to consider various reduced models capturing the properties of interest. Previous work have used tubular neighborhoods of the C-alpha backbone. However, assigning a unique radius...... might not correctly capture volume exclusion - of crucial importance when trying to understand a proteins $3$d-structure. We propose a new reduced model treating the protein as a non-uniform tube with a radius reflecting the positions of atoms. The tube representation is well suited considering X......-ray crystallographic resolution ~ 3Å while a varying radius accounts for the different sizes of side chains. Such a non-uniform tube better capture the protein geometry and has numerous applications in structural/computational biology from the classification of protein structures to sequence-structure prediction....
Unfired clay bricks – moisture properties and compressive strength
DEFF Research Database (Denmark)
Hansen, E.J. de Place; Hansen, Kurt Kielsgaard
2002-01-01
Apparatus, methods and test results from an experimental investigation of (1) the properties for moisture performance of the materials, including water vapour sorption and water vapour transmission, (2) humidity buffering of the indoor climate by an absorbent material, and (3) the compressive...... strength are presented....
Effect of elevated temperature on the compressive strength of ...
African Journals Online (AJOL)
Based on results of tests, partial replacement of cement with 10 % PSMS is recommended for use in concrete production and resistance to elevated temperature. The studies show that at this replacement, the concrete compressive strength is not adversely affected when the elevated temperature reaches 500°C. Keywords: ...
Compressive and flexural strength of cement mortar stabilized with ...
African Journals Online (AJOL)
Mortar is a material with wide range of applications in the construction industry. However, plain mortar matrices are usually brittle and often cracks and fails more suddenly than reinforced mortars. In this study, the compressive and flexural strengths of cement mortar stabilized with Raffia Palm Fruit Peel (RPFP) as fibre were ...
comparative analysis of the compressive strength of hollow
African Journals Online (AJOL)
user
2016-04-02
Apr 2, 2016 ... Previous analysis showed that cavity size and number on one hand and combinations thickness affect the compressive strength of hollow sandcrete blocks. Series arrangement of the cavities is common but parallel arrangement has been recommended. This research performed a comparative analysis of ...
optimisation of compressive strength of periwinkle shell aggregate
African Journals Online (AJOL)
user
2017-01-01
Jan 1, 2017 ... In this paper, a regression model is developed to predict and optimise the compressive strength of periwinkle shell aggregate concrete using Scheffe's regression theory. The results obtained from the derived regression model agreed favourably with the experimental data. The model was tested for ...
Effects of Elevated Temperature on Compressive Strength Of Concrete
African Journals Online (AJOL)
This study presents the results of investigation of the effects of elevated temperatures on the compressive strength of Grade 40 concrete. A total of thirty cube specimens were cast, cured in water at ambient temperature in the laboratory and subjected to various temperature regimes before testing. A concrete mix of 1:1:3 ...
Influence of curing regimes on compressive strength of ultra high
Indian Academy of Sciences (India)
The present paper is aimed to identify an efficient curing regime for ultra high performance concrete (UHPC), to achieve a target compressive strength more than 150 MPa, using indigenous materials. The thermal regime plays a vital role due to the limited fineness of ingredients and low water/binder ratio. By activation of the ...
Damaging Effects of Dieldrex-20 on the Compressive Strength of ...
African Journals Online (AJOL)
Analysis of the results showed that as the percentage of aqueous solution of dilclrex-20 increases, the compressive strength of concrete decreases. This decrease is independent of concrete grade and age. It also showed that the 5 per cent aqueous solution of dieldrex-20 recommended dosage should be strictly adhered to ...
Compressive Strength Of Rice Husk Ash-Cement Sandcrete Blocks ...
African Journals Online (AJOL)
There is growing demand for alternative, low-cost building material in developing countries. The effect of partial substitution of ordinary Portland cement with Rice Husk Ash (RHA) on the compressive strength of hollow sandcrete block was investigated through laboratory experimental procedures. The specific gravity, initial ...
Models for predicting compressive strength and water absorption of ...
African Journals Online (AJOL)
This work presents a mathematical model for predicting the compressive strength and water absorption of laterite-quarry dust cement block using augmented Scheffe's simplex lattice design. The statistical models developed can predict the mix proportion that will yield the desired property. The models were tested for lack of ...
[Compressive and bend strength of experimental admixed high copper alloys].
Sourai, P; Paximada, H; Lagouvardos, P; Douvitsas, G
1988-01-01
Mixed alloys for dental amalgams have been used mainly in the form of admixed alloys, where eutectic spheres are blend with conventional flakes. In the present study the compressive strength, bend strength and microstructure of two high-copper alloys (Tytin, Ana-2000) is compared with three experimental alloys prepared of the two high copper by mixing them in proportions of 3:1, 1:1 and 1:3 by weight. The results revealed that experimental alloys inherited high early and final strength values without any significant change in their microstructure.
International Nuclear Information System (INIS)
Sugita, Yutaka; Yui, Mikazu
2002-02-01
This report summary the dataset of the relationship between unconfined compressive strength and tensile strength of the rock mass described in supporting report 2; repository design and engineering technology of second progress report (H12 report) on research and development for the geological disposal of HLW in Japan. (author)
Insulation interlaminar shear strength testing with compression and irradiation
International Nuclear Information System (INIS)
McManamy, T.J.; Brasier, J.E.; Snook, P.
1989-01-01
The Compact Ignition Tokamak (CIT) project identified the need for research and development for the insulation to be used in the toroidal field coils. The requirements included tolerance to a combination of high compression and shear and a high radiation dose. Samples of laminate-type sheet material were obtained from commercial vendors. The materials included various combinations of epoxy, polyimide, E-glass, S-glass, and T-glass. The T-glass was in the form of a three-dimensional weave. The first tests were with 50 x 25 x 1 mm samples. These materials were loaded in compression and then to failure in shear. At 345-MPa compression, the interlaminar shear strength was generally in the range of 110 to 140 MPa for the different materials. A smaller sample configuration was developed for irradiation testing. The data before irradiation were similar to those for the larger samples but approximately 10% lower. Limited fatigue testing was also performed by cycling the shear load. No reduction in shear strength was found after 50,000 cycles at 90% of the failure stress. Because of space limitations, only three materials were chosen for irradiation: two polyimide systems and one epoxy system. All used boron-free glass. The small shear/compression samples and some flexure specimens were irradiated to 4 x 10 9 and 2 x 10 10 rad in the Advanced Technology Reactor at Idaho National Engineering Laboratory. A lead shield was used to ensure that the majority of the dose was from neutrons. The shear strength with compression before and after irradiation at the lower dose was determined. Flexure strength and the results from irradiation at the higher dose level will be available in the near future. 7 refs., 7 figs., 2 tabs
Effect Of RPC Compositions On: Compressive Strength and Absorption
Directory of Open Access Journals (Sweden)
Ahmed Sultan Ali
2016-03-01
Full Text Available Concrete is a critical material for the construction of infrastructure facilities throughout the world. A new material known as Reactive Powder Concrete (RPC, or sometimes called Ultra-High Performance Concrete (UHPC, is becoming available that differs significantly from traditional concretes. It is an ultra high strength and high ductility composite material with advanced mechanical properties. It consists of special concrete whose microstructure is optimized by precise gradation of all particles in the mix to yield maximum density. Different RPC mixes in the experimental investigation of the present study the mechanical properties of RPC including compressive strength, density and absorption. The main variables used in the production of the different RPC mixes of the present research are three, namely, type of pozzolanic admixture (metakaolin, micro silica, and silica fume, type of fibers (steel and polypropylene fibers and volume fraction of fibers (1.0,1.5, and 2.0%. The experimental results indicated that RPC mixes with silica fume gave the highest values of compressive strength and density and lowest value of absorption in comparison with RPC using micro silica or metakaolin where metakaolin was the third in such comparisons. However the RPC mixes used in the present investigation gave group compressive strength ranging between 164 -195 MPa. It was also found that the use of steel fibers with high volume fraction (2% in an RPC mix increases the compressive strength by 8% and density of the concrete by 2.5% and reduces its absorption by 13%, unlike an RPC mix using polypropylene fibers of lesser volume fraction.
Compressive Strength of Cometary Surfaces Derived from Radar Observations
ElShafie, A.; Heggy, E.
2014-12-01
Landing on a comet nucleus and probing it, mechanically using harpoons, penetrometers and drills, and electromagnetically using low frequency radar waves is a complex task that will be tackled by the Rosetta mission for Comet 67P/Churyumov-Gerasimenko. The mechanical properties (i.e. density, porosity and compressive strength) and the electrical properties (i.e. the real and imaginary parts of the dielectric constant) of the comet nucleus, constrain both the mechanical and electromagnetic probing capabilities of Rosetta, as well as the choice of landing site, the safety of the landing, and subsurface data interpretation. During landing, the sounding radar data that will be collected by Rosetta's CONSERT experiment can be used to probe the comet's upper regolith layer by assessing its dielectric properties, which are then inverted to retrieve the surface mechanical properties. These observations can help characterize the mechanical properties of the landing site, which will optimize the operation of the anchor system. In this effort, we correlate the mechanical and electrical properties of cometary analogs to each other, and derive an empirical model that can be used to retrieve density, porosity and compressive strength from the dielectric properties of the upper regolith inverted from CONSERT observations during the landing phase. In our approach we consider snow as a viable cometary material analog due to its low density and its porous nature. Therefore, we used the compressive strength and dielectric constant measurements conducted on snow at a temperature of 250 K and a density range of 0.4-0.9 g/cm3 in order to investigate the relation between compressive strength and dielectric constant under cometary-relevant density range. Our results suggest that compressive strength increases linearly as function of the dielectric constant over the observed density range mentioned above. The minimum and maximum compressive strength of 0.5 and 4.5 MPa corresponded to a
Effect of Soorh Metakaolin on Concrete Compressive Strength and Durability
Directory of Open Access Journals (Sweden)
A. Saand
2017-12-01
Full Text Available Concrete durability is a key aspect for forecasting the expected life time of concrete structures. In this paper, the effect of compressive strength and durability of concrete containing metakaolin developed from a local natural material (Soorh of Thatta Distict of Sindh, Pakistan is investigated. Soorh is calcined by an electric furnace at 8000C for 2 hours to produce metakaolin. One mix of ordinary concrete and five mixes of metakaolin concrete were prepared, where cement is replaced by developed metakaolin from 5% to 25% by weight, with 5% increment step. The concrete durability was tested for water penetration, carbonation depth and corrosion resistance. The obtained outcomes demonstrated that, 15% replacement level of local developed metakaolin presents considerable improvements in concrete properties. Moreover, a considerable linear relationship was established between compressive strength and concrete durability indicators like water penetration, carbonation depth and corrosion resistance.
Downsampling Non-Uniformly Sampled Data
Directory of Open Access Journals (Sweden)
Fredrik Gustafsson
2007-10-01
Full Text Available Decimating a uniformly sampled signal a factor D involves low-pass antialias filtering with normalized cutoff frequency 1/D followed by picking out every Dth sample. Alternatively, decimation can be done in the frequency domain using the fast Fourier transform (FFT algorithm, after zero-padding the signal and truncating the FFT. We outline three approaches to decimate non-uniformly sampled signals, which are all based on interpolation. The interpolation is done in different domains, and the inter-sample behavior does not need to be known. The first one interpolates the signal to a uniformly sampling, after which standard decimation can be applied. The second one interpolates a continuous-time convolution integral, that implements the antialias filter, after which every Dth sample can be picked out. The third frequency domain approach computes an approximate Fourier transform, after which truncation and IFFT give the desired result. Simulations indicate that the second approach is particularly useful. A thorough analysis is therefore performed for this case, using the assumption that the non-uniformly distributed sampling instants are generated by a stochastic process.
Noor, Nurazuwa Md; Xiang-ONG, Jun; Noh, Hamidun Mohd; Hamid, Noor Azlina Abdul; Kuzaiman, Salsabila; Ali, Adiwijaya
2017-11-01
Effect of inclusion of palm oil kernel shell (PKS) and palm oil fibre (POF) in concrete was investigated on the compressive strength and flexural strength. In addition, investigation of palm oil kernel shell on concrete water absorption was also conducted. Total of 48 concrete cubes and 24 concrete prisms with the size of 100mm × 100mm × 100mm and 100mm × 100mm × 500mm were prepared, respectively. Four (4) series of concrete mix consists of coarse aggregate was replaced by 0%, 25%, 50% and 75% palm kernel shell and each series were divided into two (2) main group. The first group is without POF, while the second group was mixed with the 5cm length of 0.25% of the POF volume fraction. All specimen were tested after 7 and 28 days of water curing for a compression test, and flexural test at 28 days of curing period. Water absorption test was conducted on concrete cube age 28 days. The results showed that the replacement of PKS achieves lower compressive and flexural strength in comparison with conventional concrete. However, the 25% replacement of PKS concrete showed acceptable compressive strength which within the range of requirement for structural concrete. Meanwhile, the POF which should act as matrix reinforcement showed no enhancement in flexural strength due to the balling effect in concrete. As expected, water absorption was increasing with the increasing of PKS in the concrete cause by the porous characteristics of PKS
Research of compression strength of fissured rock mass
Directory of Open Access Journals (Sweden)
А. Г. Протосеня
2017-03-01
Full Text Available The article examines a method of forecasting strength properties and their scale effect in fissured rock mass using computational modelling with final elements method in ABAQUS software. It shows advantages of this approach for solving tasks of determining mechanical properties of fissured rock mass, main stages of creating computational geomechanic model of rock mass and conducting a numerical experiment. The article presents connections between deformation during loading of numerical model, inclination angle of main fracture system from uniaxial and biaxial compression strength value, size of the sample of fissured rock mass and biaxial compression strength value under conditions of apatite-nepheline rock deposit at Plateau Rasvumchorr OAO «Apatit» in Kirovsky region of Murmanskaya oblast. We have conducted computational modelling of rock mass blocks testing in discontinuities based on real experiment using non-linear shear strength criterion of Barton – Bandis and compared results of computational experiments with data from field studies and laboratory tests. The calculation results have a high-quality match to laboratory results when testing fissured rock mass samples.
Non-uniform plastic deformation of micron scale objects
DEFF Research Database (Denmark)
Niordson, Christian Frithiof; Hutchinson, J. W.
2003-01-01
Significant increases in apparent flow strength are observed when non-uniform plastic deformation of metals occurs at the scale ranging from roughly one to ten microns. Several basic plane strain problems are analyzed numerically in this paper based on a new formulation of strain gradient...... plasticity. The problems are the tangential and normal loading of a finite rectangular block of material bonded to rigid platens and having traction-free ends, and the normal loading of a half-space by a flat, rigid punch. The solutions illustrate fundamental features of plasticity at the micron scale...... that are not captured by conventional plasticity theory. These include the role of material length parameters in establishing the size dependence of strength and the elevation of resistance to plastic flow resulting from constraint on plastic flow at boundaries. Details of the finite element method employed...
Zhang, Xiang-gang; Yang, Jian-hui; Kuang, Xiao-mei
2017-01-01
In order to study cube compressive strength and axial compressive strength of recycled lightweight aggregate concrete(RLAC), and conversion relationship between the two, with the replacement rate of recycled lightweight coarse aggregate as change parameters, 15 standard cube test specimens and 15 standard prism test specimens were produced to carry out the test. Then compressive strength of test specimens were measured, and the law of different replacement rate of recycled lightweight coarse aggregate influencing compressive strength of RLAC was analyzed, as the method of statistical regression adopted, the conversion relationships between of cube compressive strength and axial compressive strength of RLAC was obtained. It is shown that compressive strength of RLAC are lower than compressive strength of ordinary concrete; and that compressive strength of RLAC gradually decreases as replacement rate of recycled lightweight coarse aggregate increases; as well as, the conversion relationship between axial compressive strength and cube compressive strength of RLAC is different from ordinary concrete; based on the experimental data, conversion relationship formula between compressive strength indexes of RLAC was established. It is suggested that the replacement rate of recycled lightweight aggregate should be controlled within 25%.
The impact of water content and ionic diffusion on the uniaxial compressive strength of shale
Directory of Open Access Journals (Sweden)
Talal AL-Bazali
2013-12-01
Finally, the impact of ionic diffusion on the compressive strength of shale was carried out in the absence of both chemical osmosis and capillary forces. Results show that the invasion of sodium and calcium ions into shale reduced its compressive strength considerably while the invasion of potassium ions enhanced its compressive strength.
Instruction sequence based non-uniform complexity classes
Bergstra, J.A.; Middelburg, C.A.
2013-01-01
We present an approach to non-uniform complexity in which single-pass instruction sequences play a key part, and answer various questions that arise from this approach. We introduce several kinds of non-uniform complexity classes. One kind includes a counterpart of the well-known non-uniform
Scaling of compression strength in disordered solids: metallic foams
Directory of Open Access Journals (Sweden)
J. Kováčik
2016-03-01
Full Text Available The scaling of compression strength with porosity for aluminium foams was investigated. The Al 99.96, AlMg1Si0.6 and AlSi11Mg0.6 foams of various porosity, sample size with and without surface skin were tested in compression. It was observed that the compression strength of aluminium foams scales near the percolation threshold with Tf ≈ 1.9 - 2.0 almost independently on the matrix alloy, sample size and presence of surface skin. The difference of the obtained values of Tf to the theoretical estimate of Tf = 2.64 ± 0.3 by Arbabi and Sahimi and to Ashby estimate of 1.5 was explained using an analogy with the Daoud and Coniglio approach to the scaling of the free energy of sol-gel transition. It leads to the finding that, there are two different universality classes for the critical exponent Tf: when the stretching forces dominate Tf = f = 2.1, respectively when bending forces prevail Tf = .d = 2.64 seems to be valid. Another possibility is the validity of relation Tf ≤ f which varies only according to the universality class of modulus of elasticity in foam.
Compressive strength test for cemented waste forms: validation process
International Nuclear Information System (INIS)
Haucz, Maria Judite A.; Candido, Francisco Donizete; Seles, Sandro Rogerio
2007-01-01
In the Cementation Laboratory (LABCIM), of the Development Centre of the Nuclear Technology (CNEN/CDTN-MG), hazardous/radioactive wastes are incorporated in cement, to transform them into monolithic products, preventing or minimizing the contaminant release to the environment. The compressive strength test is important to evaluate the cemented product quality, in which it is determined the compression load necessary to rupture the cemented waste form. In LABCIM a specific procedure was developed to determine the compressive strength of cement waste forms based on the Brazilian Standard NBR 7215. The accreditation of this procedure is essential to assure reproductive and accurate results in the evaluation of these products. To achieve this goal the Laboratory personal implemented technical and administrative improvements in accordance with the NBR ISO/IEC 17025 standard 'General requirements for the competence of testing and calibration laboratories'. As the developed procedure was not a standard one the norm ISO/IEC 17025 requests its validation. There are some methodologies to do that. In this paper it is described the current status of the accreditation project, especially the validation process of the referred procedure and its results. (author)
Uniaxial Compressive Strengths of Rocks Drilled at Gale Crater, Mars
Peters, G. H.; Carey, E. M.; Anderson, R. C.; Abbey, W. J.; Kinnett, R.; Watkins, J. A.; Schemel, M.; Lashore, M. O.; Chasek, M. D.; Green, W.; Beegle, L. W.; Vasavada, A. R.
2018-01-01
Measuring the physical properties of geological materials is important for understanding geologic history. Yet there has never been an instrument with the purpose of measuring mechanical properties of rocks sent to another planet. The Mars Science Laboratory (MSL) rover employs the Powder Acquisition Drill System (PADS), which provides direct mechanical interaction with Martian outcrops. While the objective of the drill system is not to make scientific measurements, the drill's performance is directly influenced by the mechanical properties of the rocks it drills into. We have developed a methodology that uses the drill to indicate the uniaxial compressive strengths of rocks through comparison with performance of an identically assembled drill system in terrestrial samples of comparable sedimentary class. During this investigation, we utilize engineering data collected on Mars to calculate the percussive energy needed to maintain a prescribed rate of penetration and correlate that to rock strength.
Long GRBs sources population non-uniformity
Arkhangelskaja, Irene
Long GRBs observed in the very wide energy band. It is possible to separate two subsets of GRBs with high energy component (E > 500 MeV) presence. First type events energy spectra in low and high energy intervals are similar (as for GRB 021008) and described by Band, power law or broken power law models look like to usual bursts without emission in tens MeV region. For example, Band spectrum of GRB080916C covering 6 orders of magnitude. Second ones contain new additional high energy spectral component (for example, GRB 050525B and GRB 090902B). Both types of GRBs observed since CGRO mission beginning. The low energy precursors existence are typical for all types bursts. Both types of bursts temporal profiles can be similar in the various energy regions during some events or different in other cases. The absence of hard to soft evolution in low energy band and (or) presence of high energy precursors for some events are the special features of second class of GRBs by the results of preliminary data analysis and this facts gives opportunities to suppose differences between these two GRBs subsets sources. Also the results of long GRB redshifts distribution analysis have shown its shape contradiction to uniform population objects one for our Metagalaxy to both total and various redshifts definition methods GRBs sources samples. These evidences allow making preliminary conclusion about non-uniformity of long GRBs sources population.
Compressive and tensile strength for concrete containing coal bottom ash
Maliki, A. I. F. Ahmad; Shahidan, S.; Ali, N.; Ramzi Hannan, N. I. R.; Zuki, S. S. Mohd; Ibrahim, M. H. W.; Azmi, M. A. Mohammad; Rahim, M. Abdul
2017-11-01
The increasing demand in the construction industry will lead to the depletion of materials used in construction sites such as sand. Due to this situation, coal bottom ash (CBA) was selected as a replacement for sand. CBA is a by-product of coal combustion from power plants. CBA has particles which are angular, irregular and porous with a rough surface texture. CBA also has the appearance and particle size distribution similar to river sand. Therefore, these properties of CBA make it attractive to be used as fine aggregate replacement in concrete. The objectives of this study were to determine the properties of CBA concrete and to evaluate the optimum percentage of CBA to be used in concrete as fine aggregate replacement. The CBA was collected at Tanjung Bin power plant. The mechanical experiment (compressive and tensile strength test) was conducted on CBA concrete. Before starting the mechanical experiment, cubic and cylindrical specimens with dimensions measuring 100 × 100 × 100 mm and 150 × 300 mm were produced based on the percentage of coal bottom ash in this study which is 0% as the control specimen. Meanwhile 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100% of CBA were used to replace the fine aggregates. The CBA concrete samples were cured for 7 days and 28 days respectively to maintain the rate of hydration and moisture. After the experimental work was done, it can be concluded that the optimum percentage of CBA as fine aggregate is 60% for a curing period of both 7 days and 28 days with the total compressive strength of 36.4 Mpa and 46.2 Mpa respectively. However, the optimum percentage for tensile strength is at 70% CBA for a curing period of both 7 days and 28 days with a tensile strength of 3.03 MPa and 3.63 MPa respectively.
Compressive strength and hydrolytic stability of fly ash based geopolymers
Directory of Open Access Journals (Sweden)
Nikolić Irena
2013-01-01
Full Text Available The process of geopolymerization involves the reaction of solid aluminosilicate materials with highly alkaline silicate solution yielding an aluminosilicate inorganic polymer named geopolymer, which may be successfully applied in civil engineering as a replacement for cement. In this paper we have investigated the influence of synthesis parameters: solid to liquid ratio, NaOH concentration and the ratio of Na2SiO3/NaOH, on the mechanical properties and hydrolytic stability of fly ash based geopolymers in distilled water, sea water and simulated acid rain. The highest value of compressive strength was obtained using 10 mol dm-3 NaOH and at the Na2SiO3/NaOH ratio of 1.5. Moreover, the results have shown that mechanical properties of fly ash based geopolymers are in correlation with their hydrolytic stability. Factors that increase the compressive strength also increase the hydrolytic stability of fly ash based geopolymers. The best hydrolytic stability of fly ash based geopolymers was shown in sea water while the lowest stability was recorded in simulated acid rain. [Projekat Ministarstva nauke Republike Srbije, br. 172054 i Nanotechnology and Functional Materials Center, funded by the European FP7 project No. 245916
A dynamic model of gas flow in a non-uniform pipe
International Nuclear Information System (INIS)
Mensah, S.; Lepp, R.M.
1979-08-01
A gas-line model, based on the analysis of compressible flow with friction, has been developed to describe the dynamics of gas flow in a non-uniform line, i.e. one comprising segments of different lengths and diameters. Acoustic wave analysis was used in a novel way, by considering the line as a cascaded connection of uniform pipes separated by discontinuities. The transmission matrix representing this non-uniform line is the product of the matrices for each element in the system. To facilitate implementation of the theoretical model on a hybrid computer, modal approximatons to its transfer functions were derived. Both models were validated against experimental data. (author)
Pratama, M. Mirza Abdillah; Aylie, Han; Gan, Buntara Sthenly; Umniati, B. Sri; Risdanareni, Puput; Fauziyah, Shifa
2017-09-01
Concrete casting, compacting method, and characteristic of the concrete material determine the performance of concrete as building element due to the material uniformity issue. Previous studies show that gradation in strength exists on building member by nature and negatively influence the load carrying capacity of the member. A pilot research had modeled the concrete gradation in strength with controllable variable and observed that the weakest material determines the strength of graded concrete through uniaxial compressive loading test. This research intends to confirm the recent finding by a numerical approach with extensive variables of strength disparity. The finite element analysis was conducted using the Strand7 nonlinear program. The results displayed that the increase of strength disparity in graded concrete models leads to the slight reduction of models strength. A substantial difference in displacement response is encountered on the models for the small disparity of concrete strength. However, the higher strength of concrete mix in the graded concrete models contributes to the rise of material stiffness that provides a beneficial purpose for serviceability of building members.
Permeability, porosity and compressive strength of self-compacting concrete
Directory of Open Access Journals (Sweden)
Valcuende, M.O.
2005-12-01
Full Text Available Most deterioration affecting the durability of self-compacting concrete structures is mediated by water penetration in the concrete, a condition related to its porous structure. The present study analyzes these two factors. To this end, two types of concrete were prepared, a self-compacting and a traditional vibrated concrete, with different W/C ratios and different types of cement. The results of low-pressure water testing to evaluate permeability and analyses to determine compressive strength and pore size distribution showed that self-compacting concrete has lower capillary porosity than traditional concrete, which would explain its greater resistance to water penetration. Such concrete likewise reached higher strength values, except where large proportions of lime powder with low sand equivalents were used in its manufacture, when lower strength was recorded. Lastly, the depth of water penetration and compressive strength were found to be linearly correlated. That correlation was seen to depend, in turn, on the type of concrete, since for any given strength level, self-compacting concrete was less permeable than the traditional material.
En este trabajo experimental se estudia la penetración de agua en hormigones autocompactables, analizando al mismo tiempo su estructura porosa, pues gran parte de los procesos de deterioro que afectan a la durabilidad de las estructuras están condicionados por estos dos aspectos. Para ello se han fabricado dos tipos de hormigones, uno autocompactable y otro tradicional vibrado, con diferentes relaciones A/C y distintos tipos de cemento. Tras determinar la permeabilidad al agua bajo presión, la resistencia a compresión y las distribuciones de tamaño de poro, los resultados obtenidos ponen de manifiesto que los hormigones autocompactables presentan menor porosidad capilar que los tradicionales, lo que les confiere mejores prestaciones frente a la penetración de agua. Asimismo, dichos hormigones
A stability criterion for HNFDE with non-uniform delays
International Nuclear Information System (INIS)
Liu Xingwen; Zhong Shouming; Zhang Fengli
2005-01-01
Stability of functional differential equations (FDE) is an increasingly important problem in both science and engineering. Delays, whether uniform or non-uniform, play an important role in the dynamics of a system. Since non-uniform delay is more general and less focused than uniform delay, this paper concentrates on the stability of high-order neutral functional differential equations (HNFDE) with non-uniform delay, and proposes a sufficient condition for it. This result may be widely helpful, thanks to the frequent emergence of a HNFDE with non-uniform delay in various fields. Its effectiveness is illustrated by some examples
Confined compressive strength model of rock for drilling optimization
Directory of Open Access Journals (Sweden)
Xiangchao Shi
2015-03-01
Full Text Available The confined compressive strength (CCS plays a vital role in drilling optimization. On the basis of Jizba's experimental results, a new CCS model considering the effects of the porosity and nonlinear characteristics with increasing confining pressure has been developed. Because the confining pressure plays a fundamental role in determining the CCS of bottom-hole rock and because the theory of Terzaghi's effective stress principle is founded upon soil mechanics, which is not suitable for calculating the confining pressure in rock mechanics, the double effective stress theory, which treats the porosity as a weighting factor of the formation pore pressure, is adopted in this study. The new CCS model combined with the mechanical specific energy equation is employed to optimize the drilling parameters in two practical wells located in Sichuan basin, China, and the calculated results show that they can be used to identify the inefficient drilling situations of underbalanced drilling (UBD and overbalanced drilling (OBD.
Shear strength and compressibility behaviour of lime-treated organic clay
Yunus, NZM; Wanatowski, D; Hassan, NA; Marto, A
2016-01-01
Apart from strength characteristics, a review of studies on the compressibility of lime-treated soils is equally important that influenced the stability of soil structures. Due to the fact that no study has been carried out, an investigation on the effects of humic acid on strength and compressibility behaviour of lime-stabilised organic clay is presented in this paper. Unconfined Compressive Strength (UCS) and oedometer tests were carried out at different curing periods of 7, 28 and 90 days....
Numerical analysis of the spacer grids' compression strength
Energy Technology Data Exchange (ETDEWEB)
Schettino, C.F.M.; Gouvea, J.P.; Medeiros, N., E-mail: carlosschettino@inb.gov.br, E-mail: jpg@metal.eeimvr.uff.br [Universidade Federal Fluminense (UFF), Volta Redonda, RJ (Brazil). Programa de Engenharia Metalurgica
2013-07-01
Among the components of the fuel assembly, the spacer grids play an important structural role during the energy generation process, mainly for their requirement to have enough structural strength to withstand lateral impact loads, due to fuel assembly shipping/handling and due to forces outcome from postulated accidents (earthquake and LOCA). This requirement ensures a proper geometry for cooling and for guide thimble straightness in the fuel assembly. In this way, the understanding of the macroscopic mechanical behavior of this component becomes essential even to any subsequent geometrical modifications to optimize the flue assemblies' structural behavior. In the present work, three-dimensional finite element models destined to provide consistent predictions of 16X16-type spacer grids lateral strength were proposed. Firstly, buckling tests based on results available in the literature were performed to establish a methodology for spacer grid finite element-based modeling. The, by considering a spacer grid interesting geometry and some possible variations associated to its fabrication, tolerance, the proposed numerical models were submitted to compression conditions to calculate the buckling force. Also, these models were validated for comparison with experimental buckling load results. Comparison of buckling predictions combined to observations of actual and simulated deformed spacer grids geometries permitted to verify the consistency and applicability of the proposed models. Thus, these numerical results show a good agreement between the and the experimental results. (author)
Optimum concrete compression strength using bio-enzyme
Directory of Open Access Journals (Sweden)
Bagio Tony Hartono
2017-01-01
Full Text Available To make concrete with high compressive strength and has a certain concrete specifications other than the main concrete materials are also needed concrete mix quality control and other added material is also in line with the current technology of concrete mix that produces concrete with specific characteristics. Addition of bio enzyme on five concrete mixture that will be compared with normal concrete in order to know the optimum level bio-enzyme in concrete to increase the strength of the concrete. Concrete with bio-enzyme 200 ml/m3, 400 ml/m3, 600 ml/m3, 800 ml/m3, 1000 ml/m3 and normal concrete. Refer to the crushing test result, its tends to the mathematical model using 4th degree polynomial regression (least quartic, as represent on the attached data series, which is for the design mix fc′ = 25 MPa generate optimum value for 33,98 MPa, on the bio-additive dosage of 509 ml bio enzymes.
Numerical analysis of the spacer grids' compression strength
International Nuclear Information System (INIS)
Schettino, C.F.M.; Gouvea, J.P.; Medeiros, N.
2013-01-01
Among the components of the fuel assembly, the spacer grids play an important structural role during the energy generation process, mainly for their requirement to have enough structural strength to withstand lateral impact loads, due to fuel assembly shipping/handling and due to forces outcome from postulated accidents (earthquake and LOCA). This requirement ensures a proper geometry for cooling and for guide thimble straightness in the fuel assembly. In this way, the understanding of the macroscopic mechanical behavior of this component becomes essential even to any subsequent geometrical modifications to optimize the flue assemblies' structural behavior. In the present work, three-dimensional finite element models destined to provide consistent predictions of 16X16-type spacer grids lateral strength were proposed. Firstly, buckling tests based on results available in the literature were performed to establish a methodology for spacer grid finite element-based modeling. The, by considering a spacer grid interesting geometry and some possible variations associated to its fabrication, tolerance, the proposed numerical models were submitted to compression conditions to calculate the buckling force. Also, these models were validated for comparison with experimental buckling load results. Comparison of buckling predictions combined to observations of actual and simulated deformed spacer grids geometries permitted to verify the consistency and applicability of the proposed models. Thus, these numerical results show a good agreement between the and the experimental results. (author)
Compressive strength evolution of thermally-stressed Saint Maximin limestone.
Farquharson, J.; Griffiths, L.; Baud, P.; Wadsworth, F. B.; Heap, M. J.
2017-12-01
The Saint Maximin quarry (Oise, France) opened in the early 1600s, and its limestone has been used extensively as masonry stone, particularly during the classical era of Parisian architecture from the 17th century onwards. Its widespread use has been due to a combination of its regional availability, its high workability, and its aesthetic appeal. Notable buildings completed using this material include sections of the Place de la Concorde and the Louvre in Paris. More recently, however, it has seen increasing use in the construction of large private residences throughout the United States as well as extensions to private institutions such as Stanford University. For any large building, fire hazard can be a substantial concern, especially in tectonically active areas where catastrophic fires may arise following large-magnitude earthquakes. Typically, house fires burn at temperatures of around 600 °C ( 1000 F). Given the ubiquity of this geomaterial as a building stone, it is important to ascertain the influence of heating on the strength of Saint Maximin limestone (SML), and in turn the structural stability of the buildings it is used in. We performed a series of compressive tests and permeability measurements on samples of SML to determine its strength evolution in response to heating to incrementally higher temperatures. We observe that the uniaxial compressive strength of SML decreases from >12 MPa at room temperature to 400 °C). We anticipate that this substantial weakening is in part a result of thermal microcracking, whereby changes in temperature induce thermal stresses due to a mismatch in thermal expansion between the constituent grains. This mechanism is compounded by the volumetric increase of quartz through its alpha - beta transition at 573 °C, and by the thermal decomposition of calcite. To track the formation of thermal microcracks, we monitor acoustic emissions, a common proxy for microcracking, during the heating of an SML sample. The
Directory of Open Access Journals (Sweden)
Keun-Hyeok Yang
2015-01-01
Full Text Available This study examined the relative strength-maturity relationship of high-strength concrete (HSC specifically developed for nuclear facility structures while considering the economic efficiency and durability of the concrete. Two types of mixture proportions with water-to-binder ratios of 0.4 and 0.28 were tested under different temperature histories including (1 isothermal curing conditions of 5°C, 20°C, and 40°C and (2 terraced temperature histories of 20°C for an initial age of individual 1, 3, or 7 days and a constant temperature of 5°C for the subsequent ages. On the basis of the test results, the traditional maturity function of an equivalent age was modified to consider the offset maturity and the insignificance of subsequent curing temperature after an age of 3 days on later strength of concrete. To determine the key parameters in the maturity function, the setting behavior, apparent activation energy, and rate constant of the prepared mixtures were also measured. This study reveals that the compressive strength development of HSC cured at the reference temperature for an early age of 3 days is insignificantly affected by the subsequent curing temperature histories. The proposed maturity approach with the modified equivalent age accurately predicts the strength development of HSC.
Research on Creep Relaxation Non-uniformity and Effect on Performance of Combined Rotor
Liu, Qingya; He, Jingfei; Zhao, Lijia
2017-11-01
The combined rotor of gas turbine is connected by a certain number of rod bolts. It works in the high temperature environment for a long time, and the rod bolts will creep and relax. Under the influence of elastic interaction, the loss of pretightening force of rod bolts at different positions is non-uniform, which will cause the connection of the combined rotor to be out of tune. In this paper, the creep relaxation non-uniformity model for a class F heavy duty gas turbine is established. On the basis of this, the performance degradation and structural strength change of combined rotor resulting from creep relaxation non-uniformity of rod bolts are studied. The results show that the ratio of preload mistuning increases with time and then converges, and there is a threshold inflection point in about seven thousand hours.
Mechanical properties of Concrete with SAP. Part I: Development of compressive strength
DEFF Research Database (Denmark)
Hasholt, Marianne Tange; Jespersen, Morten H. Seneka; Jensen, Ole Mejlhede
2010-01-01
The development of mechanical properties has been studied in a test program comprising 15 different concrete mixes with 3 different w/c ratios and different additions of superabsorbent polymers (SAP). The degree of hydration is followed for 15 corresponding paste mixes. This paper concerns...... compressive strength. It shows that results agree well with a model based on the following: 1. Concrete compressive strength is proportional to compressive strength of the paste phase 2. Paste strength depends on gel space ratio, as suggested by Powers 3. The influence of air voids created by SAP...... on compressive strength can be accounted for in the same way as when taking the air content into account in Bolomeys formula. The implication of the model is that at low w/c ratios (w/c SAP additions, SAP increases the compressive strength at later ages (from 3 days after casting and onwards...
Loss of shear strength in polycrystalline tungsten under shock compression
International Nuclear Information System (INIS)
Dandekar, D.P.
1976-01-01
A reexamination of existing data on shock compression of polycrystalline tungsten at room temperature indicates that tungsten may be an exception to the common belief that metals do not behave like elastic-isotropic solids under shock compression
Colour, compressive strength and workability of mortars with an iron rich sewage sludge ash
DEFF Research Database (Denmark)
Kappel, Annemette; Ottosen, Lisbeth M.; Kirkelund, Gunvor Marie
2017-01-01
This paper reports a study of the colour, compressive strength and workability of mortar when cement is partly replaced by sewage sludge ash (SSA). In the study, an iron rich SSA was dry milled into six different fractions. The results showed that the colour, compressive strength and workability...
Prediction of potential compressive strength of Portland clinker from its mineralogy
DEFF Research Database (Denmark)
Svinning, K.; Høskuldsson, Agnar; Justnes, H.
2010-01-01
Based on a statistical model first applied for prediction of compressive strength up to 28 d from the microstructure of Portland cement, potential compressive strength of clinker has been predicted from its mineralogy. The prediction model was evaluated by partial least squares regression...
Non-uniformity Correction of Infrared Images by Midway Equalization
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Yohann Tendero
2012-07-01
Full Text Available The non-uniformity is a time-dependent noise caused by the lack of sensor equalization. We present here the detailed algorithm and on line demo of the non-uniformity correction method by midway infrared equalization. This method was designed to suit infrared images. Nevertheless, it can be applied to images produced for example by scanners, or by push-broom satellites. The obtained single image method works on static images, is fully automatic, having no user parameter, and requires no registration. It needs no camera motion compensation, no closed aperture sensor equalization and is able to correct for a fully non-linear non-uniformity.
Energy Technology Data Exchange (ETDEWEB)
Onishi, Yasuo; Baer, Ellen BK; Chun, Jaehun; Yokuda, Satoru T.; Schmidt, Andrew J.; Sande, Susan; Buchmiller, William C.
2011-02-20
K-Basin sludge will be stored in the Sludge Transport and Storage Containers (STSCs) at an interim storage location on Central Plateau before being treated and packaged for disposal. During the storage period, sludge in the STSCs may consolidate/agglomerate, potentially resulting in high-shear-strength material. The Sludge Treatment Project (STP) plans to use water jets to retrieve K-Basin sludge after the interim storage. STP has identified shear strength to be a key parameter that should be bounded to verify the operability and performance of sludge retrieval systems. Determining the range of sludge shear strength is important to gain high confidence that a water-jet retrieval system can mobilize stored K-Basin sludge from the STSCs. The shear strength measurements will provide a basis for bounding sludge properties for mobilization and erosion. Thus, it is also important to develop potential simulants to investigate these phenomena. Long-term sludge storage tests conducted by Pacific Northwest National Laboratory (PNNL) show that high-uranium-content K-Basin sludge can self-cement and form a strong sludge with a bulk shear strength of up to 65 kPa. Some of this sludge has 'paste' and 'chunks' with shear strengths of approximately 3-5 kPa and 380-770 kPa, respectively. High-uranium-content sludge samples subjected to hydrothermal testing (e.g., 185 C, 10 hours) have been observed to form agglomerates with a shear strength up to 170 kPa. These high values were estimated by measured unconfined compressive strength (UCS) obtained with a pocket penetrometer. Due to its ease of use, it is anticipated that a pocket penetrometer will be used to acquire additional shear strength data from archived K-Basin sludge samples stored at the PNNL Radiochemical Processing Laboratory (RPL) hot cells. It is uncertain whether the pocket penetrometer provides accurate shear strength measurements of the material. To assess the bounding material strength and
Effect of shelf life on compressive strength of zinc phosphate cement
Dwiputri, D. R.; Damiyanti, M.; Eriwati, Y. K.
2017-08-01
Usage of zinc phosphate cements with no account of the shelf life left before the expiry date can affect its compressive strength. The aim of this study is to determine the different compressive strength values of zinc phosphate cement with different shelf lives before expiry. Three groups of zinc phosphate cement (GC Elite cement 100) with different expiry dates were tested for compressive strength using a universal testing machine (crosshead speed 1 mm/min: load cell of 250 kgF). The results showed that there was a significant difference (p<0.05) between the compressive strengths of zinc phosphate cement in group III (2 months before expiry date), group I (2 years and 5 months before expiry date), and group II (11 months before expiry date). It can be concluded that there is a significant decrease in compressive strength of zinc phosphate cement near its expiry date.
International Nuclear Information System (INIS)
Salam, A.; Akram, M.; Shahid, K.A.; Javed, M.; Zaidi, S.M.
1994-08-01
The relationship between green compressive strength and compacting pressure as well as green density has been investigated for uniaxially pressed aluminium powder compacts in the range 0 - 520 MPa. Two linear relationships occurred between compacting pressure and green compressive strength which corresponded to powder compaction stages II and III respectively, increase in strength being large during stage II and quite small in stage III with increasing pressure. On the basis of both, the experimental results and a previous model on cold compaction of powder particles, relationships between green compressive strength and green density and interparticle contact area of the compacts has been established. (author) 9 figs
International Nuclear Information System (INIS)
Wang, Ai-juan; Yuan, Zhi-long; Zhang, Jiao; Liu, Lin-tao; Li, Jun-ming; Liu, Zheng
2013-01-01
The compressive strength of magnesium potassium phosphate chemically bonded ceramics is important in biomedical field. In this work, the compressive strength of magnesium potassium phosphate chemically bonded ceramics was investigated with different liquid-to-solid and MgO-to-KH 2 PO 4 ratios. X-ray diffractometer was applied to characterize its phase composition. The microstructure was imaged using a scanning electron microscope. The results showed that the compressive strength of the chemically bonded ceramics increased with the decrease of liquid-to-solid ratio due to the change of the packing density and the crystallinity of hydrated product. However, with the increase of MgO-to-KH 2 PO 4 weight ratio, its compressive strength increased firstly and then decreased. The low compressive strength in lower MgO-to-KH 2 PO 4 ratio might be explained by the existence of the weak phase KH 2 PO 4 . However, the low value of compressive strength with the higher MgO-to-KH 2 PO 4 ratio might be caused by lack of the joined phase in the hydrated product. Besides, it has been found that the microstructures were different in these two cases by the scanning electron microscope. Colloidal structure appeared for the samples with lower liquid-to-solid and higher MgO-to-KH 2 PO 4 ratios possibly because of the existence of amorphous hydrated products. The optimization of both liquid-to-solid and MgO-to-KH 2 PO 4 ratios was important to improve the compressive strength of magnesium potassium phosphate chemically bonded ceramics. - Highlights: • High packing density and amorphous hydrated phase improved the compressive strength. • Residual KH 2 PO 4 and poor bonding phase lower the compressive strength. • MPCBC fabricated with optimized parameters had the highest compressive strength
Non-uniform sampling of NMR relaxation data
DEFF Research Database (Denmark)
Schwarz-Linnet, Troels; Teilum, Kaare
2016-01-01
The use of non-uniform sampling of NMR spectra may give significant reductions in the data acquisition time. For quantitative experiments such as the measurement of spin relaxation rates, non-uniform sampling is however not widely used as inaccuracies in peak intensities may lead to errors...... in the extracted dynamic parameters. By systematic reducing the coverage of the Nyquist grid of (15)N Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion datasets for four different proteins and performing a full data analysis of the resulting non-uniform sampled datasets, we have compared the performance...... of the multi-dimensional decomposition and iterative re-weighted least-squares algorithms in reconstructing spectra with accurate peak intensities. As long as a single fully sampled spectrum is included in a series of otherwise non-uniform sampled two-dimensional spectra, multi-dimensional decomposition...
Fracture Energy of High-Strength Concrete in Compression
DEFF Research Database (Denmark)
Dahl, H.; Brincker, Rune
1989-01-01
is essential for understanding the fracture mechanism of concrete in compression. In this paper a series of tests is reported, carried out for the purpose of studying the fracture mechanical properties of concrete in compression. Including the measurement and study of the descending branch, a new experimental...
Su, Haijian; Jing, Hongwen; Yin, Qian; Yu, Liyuan; Wang, Yingchao; Wu, Xingjie
2017-10-01
The mechanical behaviors of rocks affected by high temperature and stress are generally believed to be significant for the stability of certain projects involving rocks, such as nuclear waste storage and geothermal resource exploitation. In this paper, veined marble specimens were treated to high temperature treatment and then used in conventional triaxial compression tests to investigate the effect of temperature, confining pressure, and vein angle on strength and deformation behaviors. The results show that the strength and deformation parameters of the veined marble specimens changed with the temperature, presenting a critical temperature of 600 °C. The triaxial compression strength of a horizontal vein (β = 90°) is obviously larger than that of a vertical vein (β = 0°). The triaxial compression strength, elasticity modulus, and secant modulus have an approximately linear relation to the confining pressure. Finally, Mohr-Coulomb and Hoek-Brown criteria were respectively used to analyze the effect of confining pressure on triaxial compression strength.
Directory of Open Access Journals (Sweden)
Kępniak M.
2016-12-01
Full Text Available This paper addresses the tensile and flexural strength of HPC (high performance concrete. The aim of the paper is to analyse the efficiency of models proposed in different codes. In particular, three design procedures from: the ACI 318 [1], Eurocode 2 [2] and the Model Code 2010 [3] are considered. The associations between design tensile strength of concrete obtained from these three codes and compressive strength are compared with experimental results of tensile strength and flexural strength by statistical tools. Experimental results of tensile strength were obtained in the splitting test. Based on this comparison, conclusions are drawn according to the fit between the design methods and the test data. The comparison shows that tensile strength and flexural strength of HPC depend on more influential factors and not only compressive strength.
Effect of Specimen Shape and Size on the Compressive Strength of Foamed Concrete
Directory of Open Access Journals (Sweden)
Sudin M.A.S.
2014-03-01
Full Text Available Lightweight concrete, in the form of foamed concrete, is a versatile material that primarily consists of a cement based mortar, mixed with at least 20% volume of air. Its dry density is typically below 1600 kg/m3 with a maximum compressive strength of 15MPa. The ASTM standard provision specifies a correction factor for concrete strength of between 14 and 42Mpa, in order to compensate for a reduced strength, when the aspect height-to-diameter ratio of a specimen is less than 2.0. However, the CEB-FIP provision specifically mentions a ratio of 150mm dia. × 300mm cylinder strength to 150 mm cube strength; though, both provision requirements do not specifically clarify the applicability and/or modification of the correction factors for the compressive strength to lightweight concrete (in this case, foamed concrete. The focus of this work is to study the effect of specimen size and shape on the axial compressive strength of concrete. Specimens of various sizes and shapes were cast with square and circular cross-sections i.e., cubes, prisms, and cylinders. Their compression strength behaviours at 7 and 28 days were investigated. The results indicate that, as the CEB-FIP provision specified, even for foamed concrete, 100mm cubes (l/d = 1.0 produce a comparable compressive strength with 100mm dia. × 200mm cylinders (l/d = 2.0.
International Nuclear Information System (INIS)
Onuma, Hiroshi; Aoyagi, Yukio
1976-01-01
The purpose of this investigation was to study the ultimate strength failure mode and deformation behavior of concrete under short-term biaxial compressive stresses, as an aid to design and analyze the concrete structures subjected to multiaxial compression such as prestressed or reinforced concrete vessel structures. The experimental work on biaxial compression was carried out on the specimens of three mix proportions and different ages with 10cm x 10cm x 10cm cubic shape in a room controlled at 20 0 C. The results are summarized as follows. (1) To minimize the surface friction between specimens and loading platens, the pads of teflon sheets coated with silicone grease were used. The coefficient of friction was measured and was 3 percent on the average. (2) The test data showed that the strength of the concrete subjected to biaxial compression increased as compared to uniaxial compressive strength, and that the biaxial strength increase was mainly dependent on the ratio of principal stresses, and it was hardly affected by mix proportions and ages. (3) The maximum increase of strength, which occurred at the stress ratio of approximately sigma 2 /sigma 1 = 0.6, was about 27 percent higher than the uniaxial strength of concrete. (4) The ultimate strength in case of biaxial compression could be approximated by the parabolic equation. (Kako, I.)
Directory of Open Access Journals (Sweden)
Xingang Wang
2014-01-01
Full Text Available This study investigated compressive strength, chloride penetration, and freeze-thaw resistance of multiwalled carbon nanotube (MWNT concrete. More than 100 cylindrical specimens were used to assess test variables during sensitivity observations, including water-cement ratios (0.75, 0.5, and 0.4 and exposure to chemical agents (including gum arabic, propanol, ethanol, sodium polyacrylate, methylcellulose, sodium dodecyl sulfate, and silane. To determine the adequate sonication time for MWNT dispersal in water, the compressive strengths of MWNT concrete cylinders were measured after sonication times ranging from 2 to 24 minutes. The results demonstrated that the addition of MWNT can increase the compressive strength of concrete by up to 108%. However, without chemical treatment, MWNT concretes tend to have poor freeze-thaw resistance. Among the different chemical treatments, MWNT concrete treated with sodium polyacrylate has the best compressive strength, chloride resistance, and freeze-thaw durability.
Wang, Xingang; Rhee, Inkyu; Wang, Yao; Xi, Yunping
2014-01-01
This study investigated compressive strength, chloride penetration, and freeze-thaw resistance of multiwalled carbon nanotube (MWNT) concrete. More than 100 cylindrical specimens were used to assess test variables during sensitivity observations, including water-cement ratios (0.75, 0.5, and 0.4) and exposure to chemical agents (including gum arabic, propanol, ethanol, sodium polyacrylate, methylcellulose, sodium dodecyl sulfate, and silane). To determine the adequate sonication time for MWNT dispersal in water, the compressive strengths of MWNT concrete cylinders were measured after sonication times ranging from 2 to 24 minutes. The results demonstrated that the addition of MWNT can increase the compressive strength of concrete by up to 108%. However, without chemical treatment, MWNT concretes tend to have poor freeze-thaw resistance. Among the different chemical treatments, MWNT concrete treated with sodium polyacrylate has the best compressive strength, chloride resistance, and freeze-thaw durability.
Directory of Open Access Journals (Sweden)
Ali Abd Elhakam Aliabdo
2012-09-01
Full Text Available This study aims to investigate the relationships between Schmidt hardness rebound number (RN and ultrasonic pulse velocity (UPV versus compressive strength (fc of stones and bricks. Four types of rocks (marble, pink lime stone, white lime stone and basalt and two types of burned bricks and lime-sand bricks were studied. Linear and non-linear models were proposed. High correlations were found between RN and UPV versus compressive strength. Validation of proposed models was assessed using other specimens for each material. Linear models for each material showed good correlations than non-linear models. General model between RN and compressive strength of tested stones and bricks showed a high correlation with regression coefficient R2 value of 0.94. Estimation of compressive strength for the studied stones and bricks using their rebound number and ultrasonic pulse velocity in a combined method was generally more reliable than using rebound number or ultrasonic pulse velocity only.
Skin carcinogenesis following uniform and non-uniform β irradiation
International Nuclear Information System (INIS)
Charles, M.W.; Williams, J.P.; Coggle, J.E.
1989-01-01
Where workers or the general public may be exposed to ionising radiation, the irradiation is rarely uniform. The risk figures and dose limits recommended by the International Commission on Radiological Protection (ICRP) are based largely on clinical and epidemiological studies of reasonably uniform irradiated organs. The paucity of clinical or experimental data for highly non-uniform exposures has prevented the ICRP from providing adequate recommendations. This weakness has led on a number of occasions to the postulate that highly non-uniform exposures of organs could be 100,000 times more carcinogenic than ICRP risk figures would predict. This so-called ''hot-particle hypothesis'' found little support among reputable radiobiologists, but could not be clearly and definitively refuted on the basis of experiment. An experiment, based on skin tumour induction in mouse skin, is described which was developed to test the hypothesis. The skin of 1200 SAS/4 male mice has been exposed to a range of uniform and non-uniform sources of the β emitter 170 Tm (E max ∼ 1 MeV). Non-uniform exposures were produced using arrays of 32 or 8 2-mm diameter sources distributed over the same 8-cm 2 area as a uniform control source. Average skin doses varied from 2-100 Gy. The results for the non-uniform sources show a 30% reduction in tumour incidence by the 32-point array at the lower mean doses compared with the response from uniform sources. The eight-point array showed an order-of-magnitude reduction in tumour incidence compared to uniform irradiation at low doses. These results, in direct contradiction to the ''hot particle hypothesis'', indicate that non-uniform exposures produce significantly fewer tumours than uniform exposures. (author)
International Nuclear Information System (INIS)
Voigt, Thomas; Malonn, Tim; Shah, Surendra P.
2006-01-01
Knowledge about the early age compressive strength development of cementitious materials is an important factor for the progress and safety of many construction projects. This paper uses cylindrical mortar specimens produced with a ram extruder to investigate the transition of the mortar from plastic and deformable to hardened state. In addition, wave transmission and reflection measurements with P- and S-waves were conducted to obtain further information about the microstructural changes during the setting and hardening process. The experiments have shown that uniaxial compression tests conducted on extruded mortar cylinders are a useful tool to evaluate the green strength as well as the initiation and further development of the compressive strength of the tested material. The propagation of P-waves was found to be indicative of the internal structure of the tested mortars as influenced, for example, by the addition of fine clay particles. S-waves used in transmission and reflection mode proved to be sensitive to the inter-particle bonding caused by the cement hydration and expressed by an increase in compressive strength
Dong, Hongying; Cao, Wanlin; Bian, Jianhui; Zhang, Jianwei
2014-01-01
In order to ascertain the fire resistance performance of recycled aggregate concrete (RAC) components with different concrete compressive strengths, four full-scaled concrete columns were designed and tested under high temperature. Two of the four specimens were constructed by normal concrete with compressive strength ratings of C20 and C30, respectively, while the others were made from recycled coarse aggregate (RCA) concrete of C30 and C40, respectively. Identical constant axial forces were...
Face compression yield strength of the copper-Inconel composite specimen
International Nuclear Information System (INIS)
Horie, T.
1987-05-01
A new equation for the face compression yield strength of copper-Inconel composite material has been derived. Elastic-plastic finite element analyses were also made for composite specimens with various aspect ratios to examine the edge effect of the specimen. According to the results of both the new equation and the analyses, the face compression yield strength of the composite should be decreased by about 25% from the value obtained with Becker's equation
Assessment indices for uniform and non-uniform thermal environments
Institute of Scientific and Technical Information of China (English)
2008-01-01
Different assessment indices for thermal environments were compared and selected for proper assessment of indoor thermal environments.30 subjects reported their overall thermal sensation,thermal comfort,and thermal acceptability in uniform and non-uniform conditions.The results show that these three assessment indices provide equivalent evaluations in uniform environments.However,overall thermal sensation differs from the other two indices and cannot be used as a proper index for the evaluation of non-uniform environments.The relationship between the percentage and the mean vote for each index is established.
Analysis of the Optimum Usage of Slag for the Compressive Strength of Concrete.
Lee, Han-Seung; Wang, Xiao-Yong; Zhang, Li-Na; Koh, Kyung-Taek
2015-03-18
Ground granulated blast furnace slag is widely used as a mineral admixture to replace partial Portland cement in the concrete industry. As the amount of slag increases, the late-age compressive strength of concrete mixtures increases. However, after an optimum point, any further increase in slag does not improve the late-age compressive strength. This optimum replacement ratio of slag is a crucial factor for its efficient use in the concrete industry. This paper proposes a numerical procedure to analyze the optimum usage of slag for the compressive strength of concrete. This numerical procedure starts with a blended hydration model that simulates cement hydration, slag reaction, and interactions between cement hydration and slag reaction. The amount of calcium silicate hydrate (CSH) is calculated considering the contributions from cement hydration and slag reaction. Then, by using the CSH contents, the compressive strength of the slag-blended concrete is evaluated. Finally, based on the parameter analysis of the compressive strength development of concrete with different slag inclusions, the optimum usage of slag in concrete mixtures is determined to be approximately 40% of the total binder content. The proposed model is verified through experimental results of the compressive strength of slag-blended concrete with different water-to-binder ratios and different slag inclusions.
Influence of bottom ash of palm oil on compressive strength of concrete
Saputra, Andika Ade Indra; Basyaruddin, Laksono, Muhamad Hasby; Muntaha, Mohamad
2017-11-01
The technological development of concrete demands innovation regarding the alternative material as a part of the effort in improving quality and minimizing reliance on currently used raw materials such as bottom ash of palm oil. Bottom ash known as domestic waste stemming from palm oil cultivation in East Kalimantan contains silica. Like cement in texture and size, bottom ash can be mixed with concrete in which the silica in concrete could help increase the compressive strength of concrete. This research was conducted by comparing between normal concrete and concrete containing bottom ash as which the materials were apart of cement replacement. The bottom ash used in this research had to pass sieve size (#200). The composition tested in this research involved ratio between cement and bottom ash with the following percentages: 100%: 0%, 90%: 10%, 85%: 15% and 80%: 20%. Planned to be within the same amount of compressive strength (fc 25 MPa), the compressive strength of concrete was tested at the age of 7, 14, and 28 days. Research result shows that the addition of bottom ash to concrete influenced workability in concrete, but it did not significantly influence the compressive strength of concrete. Based on the result of compressive strength test, the optimal compressive strength was obtained from the mixture of 100% cement and 0% bottom ash.
Effect of Pelletized Coconut Fibre on the Compressive Strength of Foamed Concrete
Directory of Open Access Journals (Sweden)
Mohd Jaini Zainorizuan
2016-01-01
Full Text Available Foamed concrete is a controlled low density ranging from 400kg/m3 to 1800kg/m3, and hence suitable for the construction of buildings and infrastructures. The uniqueness of foamed concrete is does not use aggregates in order to retain low density. Foamed concrete contains only cement, sand, water and foam agent. Therefore, the consumption of cement is higher in producing a good quality and strength of foamed concrete. Without the present of aggregates, the compressive strength of foamed concrete can only achieve as high as 15MPa. Therefore, this study aims to introduce the pelletized coconut fibre aggregate to reduce the consumption of cement but able to enhance the compressive strength. In the experimental study, forty-five (45 cube samples of foamed concrete with density 1600kg/m3 were prepared with different volume fractions of pelletized coconut fibre aggregate. All cube samples were tested using the compression test to obtain compressive strength. The results showed that the compressive strength of foamed concrete containing 5%, 10%, 15% and 20% of pelletized coconut fibre aggregate are 9.6MPa, 11.4MPa, 14.6MPa and 13.4MPa respectively. It is in fact higher than the controlled foamed concrete that only achieves 9MPa. It is found that the pelletized coconut fibre aggregate indicates a good potential to enhance the compressive strength of foamed concrete.
Measurement and Improvement the Quality of the Compressive Strength of Product Concrete
Directory of Open Access Journals (Sweden)
Zohair Hassan Abdullah
2018-01-01
Full Text Available The research dealt with studying path technology to manufacture of concrete cubes according to specification design of Iraq to the degree of concrete C20 No. 52 of 1984, and in which sample was cubic shape and the dimensions (150 × 150 × 150 mm for each dimensions and the proportion of mixing of the concrete is (1:2:4 using in the casting floor. For concrete resistance required that achieve the degree of confidence of 100%, were examined compressive strength 40 samples of concrete cubes of age 28 days in the Labs section of Civil Department – Technical Institute of Babylon, all made from the same mixing concrete. Where, these samples classified within the acceptable tests were adopted in the implementation of investment projects in the construction sector. The research aims first, to measure the compressive strength of concrete cubes because the decrease or increase the compressive strength from specification design contributes to the failure of investment projects in the construction sector therefore, test was classified units that produced within damaged units. Second, to study an improvement the quality of compressive strength of concrete cubes. Results show that the proportion of damaged cubes are 0.00685, compressive strength was achieve confidence level 99.5% and producing of concrete cubes within the acceptable level of quality (3 Sigma. The quality of compressive strength was improved to good level use advanced sigma levels. DOI: http://dx.doi.org/10.25130/tjes.24.2017.20
33 Effects of Sodium Chloride Solutions on Compressive Strength ...
African Journals Online (AJOL)
Arc. Usman A. Jalam
strength increase at 3 and 7 days over control cubes; at 28 days concrete cubes containing 5%. RHA cured in NaCl solutions recorded higher strength loss compared to control cubes. Keywords: ... chloride in mixing water reported it to cause.
Predicting the Compressive Strength of Concretes Made with ...
African Journals Online (AJOL)
Cases of collapsed buildings and structures are prevalent in Nigeria. In most of these cases the cause of the collapse could be traced to the strength of the construction materials, mainly concrete. Secondly, experimental determination of the strength of concrete materials used in buildings and structures is quite expensive ...
Post-Buckling Strength of Uniformly Compressed Plates
Bakker, M.C.M.; Rosmanit, M.; Hofmeyer, H.; Camotim, D; Silvestre, N; Dinis, P.B.
2006-01-01
In this paper it is discussed how existing analytical and semi-analytical formulas for describing the elastic-post-buckling behavior of uniformly compressed square plates with initial imperfections, for loads up to three times the buckling load can be simplified and improved. For loads larger than
Application of size effect to compressive strength of concrete members
Indian Academy of Sciences (India)
R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22
(LSM) to obtain parameters for the modified size effect law (MSEL) by Kim and co workers. The results of the ... in tensile failure, because the formation of microcracks in compressive failure is distributed in a wider region ...... Benjamin J R, Cornell C A 1970 Probability, statistics, and decision for civil engineers (New York:.
strength properties of shea-butter nuts under compressive loading
African Journals Online (AJOL)
NIJOTECH
Compression tests were performed on heat-treated Shea-butter nuts to study the effects of ... the only source of vegetable oil. It was also .... the longitudinal axis, while in the lateral loading position ... Multiple Range Test (DMRT) was used to.
Identification of Bacteria and the Effect on Compressive Strength of Concrete
Directory of Open Access Journals (Sweden)
Anneza L. H.
2016-01-01
Full Text Available This paper presents the species of bacteria used in this study as well as the effect of the bacteria on compressive strength of bioconcrete. Bioconcrete is not only more environmentally friendly but it is easy to procure. The objective of this research is to identify the ureolytic bacteria and sulphate reduction bacteria that have been isolated and further use the bacteria in concrete to determine the effect of bacteria on compressive strength. Identification of bacteria is conducted through Polymerase chain reaction (PCR method and DNA sequencing. The DNA of the bacteria was run through BLAST algorithm to determine the bacterial species.The bacteria were added into the concrete mix as a partial replacement of water. 3% of water is replaced by ureolytic bacteria and 5% of water is replaced by sulphate reduction bacteria. After running BLAST algorithm the bacteria were identified as Enterococcus faecalis (ureolytic bacteria and Bacillus sp (sulphate reduction bacteria. The result of the compressive strength for control is 36.0 Mpa. Partial replacement of 3% water by ureolytic bacteria has strength of 38.2Mpa while partial replacement of 5% of water by sulphate reduction bacteria has strength of 42.5Mpa. The significant increase of compressive strength with the addition of bacteria shows that bacteria play a significant role in the improvement of compressive strength.
Exact Finite Differences. The Derivative on Non Uniformly Spaced Partitions
Directory of Open Access Journals (Sweden)
Armando Martínez-Pérez
2017-10-01
Full Text Available We define a finite-differences derivative operation, on a non uniformly spaced partition, which has the exponential function as an exact eigenvector. We discuss some properties of this operator and we propose a definition for the components of a finite-differences momentum operator. This allows us to perform exact discrete calculations.
Instruction sequences and non-uniform complexity theory
Bergstra, J.A.; Middelburg, C.A.
2008-01-01
We develop theory concerning non-uniform complexity in a setting in which the notion of single-pass instruction sequence considered in program algebra is the central notion. We define counterparts of the complexity classes P/poly and NP/poly and formulate a counterpart of the complexity theoretic
Leveraging Non-Uniform Resources for Parallel Query Processing
DEFF Research Database (Denmark)
Mayr, Tobias; Bonnet, Philippe; Gehrke, Johannes
2003-01-01
Modular clusters are now composed of non- uniform nodes with different CPUs, disks or network cards so that customers can adapt the cluster configuration to the changing technologies and to their changing needs. This challenges dataflow parallelism as the primary load balancing technique of exist...
Compressive Strength Characteristics of Carbon, Palm Kernel and ...
African Journals Online (AJOL)
ADOWIE PERE
2018-03-15
Mar 15, 2018 ... reinforced concrete was one of the topics of interest. Once the health risks ... over the Portland cement concrete, some of which includes higher strength ... be used in the construction industry as a binder for aggregates.
compressive and flexural strength of cement mortar stabilized with ...
African Journals Online (AJOL)
PROF. BARTH EKWEME
concrete. However, plain mortar materials are usually brittle and often crack more easily and fail more suddenly than ... impact strength, higher elastic modulus, better sound proofness ..... in Concrete. Unpublished Ph.D. Thesis, Department.
Directory of Open Access Journals (Sweden)
Ramadhan W. Salim
2014-06-01
Full Text Available The need for affordable and sustainable alternative construction materials to cement in developing countries cannot be underemphasized. Compressed Earth Bricks have gained acceptability as an affordable and sustainable construction material. There is however a need to boost its bearing capacity. Previous research show that Sugarcane Bagasse Ash as a soil stabilizer has yielded positive results. However, there is limited research on its effect on the mechanical property of Compressed Earth Brick. This current research investigated the effect of adding 3%, 5%, 8% and 10% Sugarcane Bagasse Ash on the compressive strength of compressed earth brick. The result showed improvement in its compressive strength by 65% with the addition of 10% Sugarcane Bagasse Ash.
Estimation of hardness and compressive strength of SP 100 aluminum powder epoxy
Energy Technology Data Exchange (ETDEWEB)
Han, Jeong Young [Pusan National Univ., Busan (Korea, Republic of); Kim, Myung Hun [Korea Institute of Footwear and Leather Technology, Busan (Korea, Republic of); Kang, Sung Soo [Jeonju Univ., Jeonju (Korea, Republic of)
2012-09-15
In this study, we performed experimental tests on five SP 100 aluminum powder epoxy specimens with several after curing conditions in order to estimate their hardness with temperature and compressive strength. In the surface hardness test, it was found that the higher the after curing temperature, the higher was the hardness. In particular, it was found that the hardness of the specimens in cases 3 and 4 was much higher than in the other cases. In addition, in the compression tests carried out to evaluate the compressive strength, it was found that the specimens showed relatively similar stiffness and strength with after curing, and specimens with no after curing showed compression stress strain curves similar to those of thermoplastic resins.
Estimation of hardness and compressive strength of SP 100 aluminum powder epoxy
International Nuclear Information System (INIS)
Han, Jeong Young; Kim, Myung Hun; Kang, Sung Soo
2012-01-01
In this study, we performed experimental tests on five SP 100 aluminum powder epoxy specimens with several after curing conditions in order to estimate their hardness with temperature and compressive strength. In the surface hardness test, it was found that the higher the after curing temperature, the higher was the hardness. In particular, it was found that the hardness of the specimens in cases 3 and 4 was much higher than in the other cases. In addition, in the compression tests carried out to evaluate the compressive strength, it was found that the specimens showed relatively similar stiffness and strength with after curing, and specimens with no after curing showed compression stress strain curves similar to those of thermoplastic resins
Enhancing the compressive strength of landfill soil using cement and bagasse ash
Azim, M. A. M.; Azhar, A. T. S.; Tarmizi, A. K. A.; Shahidan, S.; Nabila, A. T. A.
2017-11-01
The stabilisation of contaminated soil with cement and agricultural waste is a widely applied method which contributes to the sustainability of the environment. Soil may be stabilised to increase strength and durability or to prevent erosion and other geotechnical failure. This study was carried out to evaluate the compressive strength of ex-landfill soil when cement and bagasse ash (BA) are added to it. Different proportions of cement (5%, 10%, 15% and 20%) was added to sample weights without BA. On the other hand, the cement in a different batch of sample weights was replaced by 2.5%, 5%, 7.5% and 10% of BA. All samples were allowed to harden and were cured at room temperature for 7, 14 and 28 days respectively. The strength of the contaminated soil was assessed using an unconfined compressive strength test (UCS). The laboratory tests also included the index properties of soil, cement and bagasse ash in raw form. The results indicated that the samples with cement achieved the highest compressive strength measuring 4.39 MPa. However, this study revealed that the use of bagasse ash produced low quality products with a reduction in strength. For example, when 5% of cement was replaced with 5% ash, the compressive strength decreased by about 54% from 0.72 MPa to 0.33 MPa. Similarly, the compressive strength of each sample after a curing period of 28 days was higher compared to samples cured for 7 and 14 days respectively. This is proved that a longer curing period is needed to increase the compressive strength of the samples.
Subaer, Ekaputri, Januari Jaya; Fansuri, Hamzah; Abdullah, Mustafa Al Bakri
2017-09-01
An experimental study to investigate the relationship between Vickers microhardness and compressive strength of geopolymers made from metakaolin has been conducted. Samples were prepared by using metakaolin activated with a sodium silicate solution at a different ratio of Si to Al and Na to Al and cured at 70oC for one hour. The resulting geopolymers were stored in an open air for 28 days before conducting any measurement. Bulk density and apparent porosity of the samples were measured by using Archimedes's method. Vickers microhardness measurements were performed on a polished surface of geopolymers with a load ranging from 0.3 - 1.0 kg. The topographic of indented samples were examined by using scanning electron microscopy (SEM). Compressive strength of the resulting geopolymers was measured on the cylindrical samples with a ratio of height to the diameter was 2:1. The results showed that the molar ratios of geopolymers compositions play important roles in the magnitude of bulk density, porosity, Vickers's microhardness as well as the compressive strength. The porosity reduced exponentially the magnitude of the strength of geopolymers. It was found that the relationship between Vickers microhardness and compressive strength was linear. At the request of all authors and with the approval of the proceedings editor, article 020188 titled, "The relationship between vickers microhardness and compressive strength of functional surface geopolymers," is being retracted from the public record due to the fact that it is a duplication of article 020170 published in the same volume.
Multiple Regression Analysis of Unconfined Compression Strength of Mine Tailings Matrices
Directory of Open Access Journals (Sweden)
Mahmood Ali A.
2017-01-01
Full Text Available As part of a novel approach of sustainable development of mine tailings, experimental and numerical analysis is carried out on newly formulated tailings matrices. Several physical characteristic tests are carried out including the unconfined compression strength test to ascertain the integrity of these matrices when subjected to loading. The current paper attempts a multiple regression analysis of the unconfined compressive strength test results of these matrices to investigate the most pertinent factors affecting their strength. Results of this analysis showed that the suggested equation is reasonably applicable to the range of binder combinations used.
Strength of tensed and compressed concrete segments in crack spacing under short-term dynamic load
Directory of Open Access Journals (Sweden)
Galyautdinov Zaur
2018-01-01
Full Text Available Formation of model describing dynamic straining of reinforced concrete requires taking into account the basic aspects influencing the stress-strain state of structures. Strength of concrete segments in crack spacing is one of the crucial aspects that affect general strain behavior of reinforced concrete. Experimental results demonstrate significant change in strength of tensed and compressed concrete segments in crack spacing both under static and under dynamic loading. In this case, strength depends on tensile strain level and the slope angle of rebars towards the cracks direction. Existing theoretical and experimental studies estimate strength of concrete segments in crack spacing under static loading. The present work presents results of experimental and theoretical studies of dynamic strength of plates between cracks subjected to compression-tension. Experimental data was analyzed statistically; the dependences were suggested to describe dynamic strength of concrete segments depending on tensile strain level and slope angle of rebars to cracks direction.
Effect of shelf life on compressive strength of type iv gypsum
Kusumastuti, K. S.; Irawan, B.; Damiyanti, M.
2017-08-01
Type IV gypsum, as a dental material for an indirect restoration’s working model, should have strength and abrasive-resistant properties. These properties depend on the product’s shelf life and its proper storage, which sometimes are easily missed by sellers. The aim of this research was to observe the effect of shelf life on the compressive strength of type IV gypsum with different production dates. Twenty cylindrical specimens were separated into two groups with different production dates and tested with a universal testing with the crosshead speed of 1 mm per minute and a load of 2,500 kgf. The data were analyzed with independent t-tests. There was a significant difference (p<0.05) in the compressive strength between the two groups with an increase in compressive strength seen in the gypsum that was stored longer.
International Nuclear Information System (INIS)
Khan, Z.M.
1997-01-01
As advanced composite materials having superior physical and mechanical properties are being developed, optimization of their production processes in eagerly being sought. One of the most common defect in production of structural composites is layer waviness. Layer waviness is more pronounced in thick section flat and cylindrical laminates that are extensively used in missile casings, submersibles and space platforms. Layer waviness undulates the entire layers of a multidirectional laminate in through-the-thickness direction leading to gross deterioration of its compression strength. This research investigates the influence of multiple layer waviness in a double nest formation on the compression strength of a composite laminate. Different wave fractions of wave 0 degree centigrade layer fabricated in IM/85510-7 carbon - epoxy composite laminate on a steel mold using single step fabrication procedure. The laminate was cured on a heated press according to specific curing cycle. Static compression testing was performed using NASA short block compression fixture on an MTS servo Hydraulic machine. The purpose of these tests was to determine the effects of multiple layer wave regions on the compression strength of composite laminate. The experimental and analytical results revealed that up to about 35% fraction of wave 0 degree layer exceeded 35%. This analysis indicated that the percentage of 0 degree wavy layer may be used to estimate the reduction in compression strength of a composite laminate under restricted conditions. (author)
The increase of compressive strength of natural polymer modified concrete with Moringa oleifera
Susilorini, Rr. M. I. Retno; Santosa, Budi; Rejeki, V. G. Sri; Riangsari, M. F. Devita; Hananta, Yan's. Dianaga
2017-03-01
Polymer modified concrete is one of some concrete technology innovations to meet the need of strong and durable concrete. Previous research found that Moringa oleifera can be applied as natural polymer modifiers into mortars. Natural polymer modified mortar using Moringa oleifera is proven to increase their compressive strength significantly. In this resesearch, Moringa oleifera seeds have been grinded and added into concrete mix for natural polymer modified concrete, based on the optimum composition of previous research. The research investigated the increase of compressive strength of polymer modified concrete with Moringa oleifera as natural polymer modifiers. There were 3 compositions of natural polymer modified concrete with Moringa oleifera referred to previous research optimum compositions. Several cylinder of 10 cm x 20 cm specimens were produced and tested for compressive strength at age 7, 14, and, 28 days. The research meets conclusions: (1) Natural polymer modified concrete with Moringa oleifera, with and without skin, has higher compressive strength compared to natural polymer modified mortar with Moringa oleifera and also control specimens; (2) Natural polymer modified concrete with Moringa oleifera without skin is achieved by specimens contains Moringa oleifera that is 0.2% of cement weight; and (3) The compressive strength increase of natural polymer modified concrete with Moringa oleifera without skin is about 168.11-221.29% compared to control specimens
Dong, Hongying; Cao, Wanlin; Bian, Jianhui; Zhang, Jianwei
2014-12-08
In order to ascertain the fire resistance performance of recycled aggregate concrete (RAC) components with different concrete compressive strengths, four full-scaled concrete columns were designed and tested under high temperature. Two of the four specimens were constructed by normal concrete with compressive strength ratings of C20 and C30, respectively, while the others were made from recycled coarse aggregate (RCA) concrete of C30 and C40, respectively. Identical constant axial forces were applied to specimens while being subjected to simulated building fire conditions in a laboratory furnace. Several parameters from the experimental results were comparatively analyzed, including the temperature change, vertical displacement, lateral deflection, fire endurance, and failure characteristics of specimens. The temperature field of specimens was simulated with ABAQUS Software (ABAQUS Inc., Provindence, RI, USA) and the results agreed quite well with those from the experiments. Results show that the rate of heat transfer from the surface to the interior of the column increases with the increase of the concrete's compressive strength for both RAC columns and normal concrete columns. Under the same initial axial force ratio, for columns with the same cross section, those with lower concrete compressive strengths demonstrate better fire resistance performance. The fire resistance performance of RAC columns is better than that of normal concrete columns, with the same concrete compressive strength.
Investigation on Compressive Strength of Special Concrete made with Crushed Waste Glass
Directory of Open Access Journals (Sweden)
Mohd Sani Mohd Syahrul Hisyam
2015-01-01
Full Text Available Special concrete is the type of concrete that produced by using waste material or using unusual techniques/method of preparation. Special concrete made with waste material is becoming popular in a construction site. This is because the special concrete is selected due to quality, integrity, economic factor and environmental factor. The waste glass is selected as an additional material to provide a good in compressive strength value. The compressive strength is the importance of mechanical properties of concrete and typically the concrete is sustained and stiffed in compression load. The significant issue to utilize the waste glass from the automotive windscreen is to improve the strength of concrete. The waste glass is crushed to become 5 mm size and recognised as crushed waste glass that be used in concrete as additional material. The main objective of the study is to determine the appropriate percentage of crushed waste glass in concrete grade, 30 in order to enhance the compressive strength. There are four mixes of concrete that contained of crushed waste glass with percentage of 2 %, 4 %, 6 % and 8 % and one control mix with 0 % of crushed waste glass. As the result, crushed waste glass with an additional 4 % in concrete is reported having a higher value of compressive strength in early and mature stage. In addition, if the percentage of crushed glass wastes in concrete increases and it leads to a reduction in the workability of concrete.
Pizoń, Jan; Łaźniewska-Piekarczyk, Beata
2017-10-01
One of disadvantages of accelerating admixtures usage is possibility of significant decline of long-term compressive strength of concrete in comparison to non-modified one. Described tests were intended to define scale of lowered long-term compressive strength of mortars caused by accelerating admixtures in different curing conditions. Portland cement and blended cement with ground granulated blast furnace slag (GGBFS) addition and four types of non-chloride accelerating agents were used. Compressive strength was tested after 7 up to 360 days. Curing conditions were designed to simulate probable conditions close to reality. Such conditions are simulation of internal concrete elements, external elements cast on start of summer and external elements cast on start of winter. Results had shown that it is invalid to state that every accelerating admixture will cause drop of long-term compressive strength in every conditions and for every cement type. Change of curing conditions even after a long time (in this case half of the year) leads to significant differences in compression strength.
Rum, R. H. M.; Jaini, Z. M.; Boon, K. H.; Khairaddin, S. A. A.; Rahman, N. A.
2017-11-01
This study presents the utilization of rice husk ash (RHA) as sand replacement in foamed concrete. The study focuses on the effect of RHA on the compressive strength of foamed concrete. RHA contains high pozzolanic material that reacts with cementitious to enhance the strength and durability of foamed concrete. RHA also acts as filler causing the foamed concrete to become denser while retaining its unique low density. A total 243 cube specimens was prepared for the compression test. Two sets of mix design were employed at water-cement (W/C) ratio of 0.55, 0.60 and cement-sand ratio of 0.50, 0.33. The results revealed that the presence of RHA as sand replacement resulted in an increase in the compressive strength of foamed concrete. Moreover, 30% to 40% RHA was the optimum content level, contributing to the compressive strength of 18.1 MPa to 22.4 MPa. The W/C ratio and superplasticiser dosage play small roles in improving workability. In contrast, density governs the compressive strength of foamed concrete.
Dong, Hongying; Cao, Wanlin; Bian, Jianhui; Zhang, Jianwei
2014-01-01
In order to ascertain the fire resistance performance of recycled aggregate concrete (RAC) components with different concrete compressive strengths, four full-scaled concrete columns were designed and tested under high temperature. Two of the four specimens were constructed by normal concrete with compressive strength ratings of C20 and C30, respectively, while the others were made from recycled coarse aggregate (RCA) concrete of C30 and C40, respectively. Identical constant axial forces were applied to specimens while being subjected to simulated building fire conditions in a laboratory furnace. Several parameters from the experimental results were comparatively analyzed, including the temperature change, vertical displacement, lateral deflection, fire endurance, and failure characteristics of specimens. The temperature field of specimens was simulated with ABAQUS Software (ABAQUS Inc., Provindence, RI, USA) and the results agreed quite well with those from the experiments. Results show that the rate of heat transfer from the surface to the interior of the column increases with the increase of the concrete’s compressive strength for both RAC columns and normal concrete columns. Under the same initial axial force ratio, for columns with the same cross section, those with lower concrete compressive strengths demonstrate better fire resistance performance. The fire resistance performance of RAC columns is better than that of normal concrete columns, with the same concrete compressive strength. PMID:28788279
Effect of Pressure and Heat Treatments on the Compressive Strength of Reactive Powder Concrete
Directory of Open Access Journals (Sweden)
Helmi Masdar
2018-01-01
Full Text Available This paper presents the corresponding compressive strength of RPC with variable pressure combined with heating rate, heating duration, and starting time of heating. The treatments applied were 8 MPa static pressure on fresh RPC prims and heat curing at 240 °C in an oven. The compressive strength test was conducted at 7-d and 28-d. The images of RPC morphology were captured on the surface of a fractured specimen using Scanning Electron Microscopy in Secondary Electron detector mode to describe pore filing mechanism after treatments. The results show that a heating rate at 50 °C/hr resulted in the highest compressive strength about 40 % more than those at 10 or 100 °C/hr. A heating duration of 48 hours led to the maximum compressive strength. Heat curing applied 2 days after casting resulted in the maximum compressive. Heat curing had a signicant effect on the compresssive strength due to the acceleration of both reactions (hydration and pozzolanic and the degree of transformation from tobermorite to xonotlite. It is concluded that the optimum condition of treatments is both pressure and heat curing at 2-day after casting with a rate of 50 °C/hr for 48 hours.
Predicting of the compressive strength of RCA concrete
Directory of Open Access Journals (Sweden)
Jaskulski Roman
2017-01-01
Full Text Available The paper presents the results of predicting the strength of 61 concretes made with the use of recycled concrete aggregate (RCA. Five models in the form of first-order polynomials containing two to six variables characterizing the composition of the mixture were formulated for this purpose. Factors for unknowns were selected using linear regression in two variants: with and without additional coefficient. For each model, the average absolute error of the concrete strength estimation was determined. Because of the various consequences of underestimation and overestimation of the results, the analysis of models quality was carried out with the distinction of the two cases. The results indicate that the key to improving the quality of models is to take into account the quality of the aggregate expressed by the ACV parameter. Better match results were also obtained for models with more variables and the additional coefficient.
Non-uniformity measurements of PbWO4 crystals
International Nuclear Information System (INIS)
Depasse, P.; Ernenwein, J.P.; Ille, B.; Martin, F.; Rosset, C.; Zach, F.
1998-11-01
Two independent methods have been used to measure the longitudinal non-uniformity scintillation response of 3 different (23-cm long) PbWO 4 crystals. The first one is the classical 60 Co source method. The source is collimated along the crystal, each 1,5-cm, and the scintillation signal is measured with a photomultiplier (a hybrid photomultiplier in our case). The second one is the use of cosmic particles (Minimum Ionizing Particles). A cosmic bench allows reconstructing the track of the MIP's and thus the energy deposit with the help of a full GEANT simulation of the setup. Variations of E along the crystal artificially cut in 1,5-cm divisions, leads to determine the non-uniformity. The conclusion is that both methods agree quite well. Furthermore, a good estimation of crystal light yield can be obtained. (author)
Non-uniformity of phase structure in immiscible polymer blends
Czech Academy of Sciences Publication Activity Database
Fortelný, Ivan; Lapčíková, Monika; Lednický, František; Starý, Zdeněk; Kruliš, Zdeněk
2008-01-01
Roč. 48, č. 3 (2008), s. 564-571 ISSN 0032-3888 R&D Projects: GA ČR GA106/06/0729; GA ČR GA106/06/0761 Institutional research plan: CEZ:AV0Z40500505 Keywords : polymer blends * melt mixing * non-uniform morphology Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.245, year: 2008
Dataset on predictive compressive strength model for self-compacting concrete.
Ofuyatan, O M; Edeki, S O
2018-04-01
The determination of compressive strength is affected by many variables such as the water cement (WC) ratio, the superplasticizer (SP), the aggregate combination, and the binder combination. In this dataset article, 7, 28, and 90-day compressive strength models are derived using statistical analysis. The response surface methodology is used toinvestigate the effect of the parameters: Varying percentages of ash, cement, WC, and SP on hardened properties-compressive strengthat 7,28 and 90 days. Thelevels of independent parameters are determinedbased on preliminary experiments. The experimental values for compressive strengthat 7, 28 and 90 days and modulus of elasticity underdifferent treatment conditions are also discussed and presented.These dataset can effectively be used for modelling and prediction in concrete production settings.
Compressive Strength of Volcanic Ash/Ordinary Portland Cement Laterized Concrete
Directory of Open Access Journals (Sweden)
Olusola K. O.
2010-01-01
Full Text Available This study investigates the effect of partial replacement of cement with volcanic ash (VA on the compressive strength of laterized concrete. A total of 192 cubes of 150mm dimensions were cast and cured in water for 7, 14, 21, and 28 days of hydration with cement replacement by VA and sand replacement by laterite both ranging from 0 to 30% respectively, while a control mix of 28-day target strength of 25 N/mm2 was adopted. The results show that the density and compressive strength of concrete decreased with increase in volcanic ash content. The 28-day, density dropped from 2390 kg/m3 to 2285 kg/m3 (i.e. 4.4% loss and the compressive strength from 25.08 N/mm2 to 17.98 N/mm2 (i.e. 28% loss for 0-30% variation of VA content with no laterite introduced. The compressive strength also decreased with increase in laterite content; the strength of the laterized concrete however increases as the curing age progresses.
Zulkifeli, Muhamad Faqrul Hisham bin Mohd; Saman@Hj Mohamed, Hamidah binti Mohd
2017-08-01
Work on thermal resistant of outer structures of buildings is one of the solution to reduce death, damages and properties loss in fire cases. Structures protected with thermal resistant materials can delay or avoid failure and collapse during fire. Hence, establishment of skin cladding with advance materials to protect the structure of buildings is a necessary action. Expanded perlite is a good insulation material which can be used as aggregate replacement in mortar. This study is to study on mortar mechanical properties of flexural and compressive strength subjected to elevated temperatures using expanded perlite aggregate (EPA). This study involved experimental work which was developing mortar with sand replacement by volume of 0%, 10%, 20%, 30% and 40% of EPA and cured for 56 days. The mortars then exposed to 200°C, 400 °C, 700 °C and 1000 °C. Flexural and compressive strength of the mortar were tested. The tests showed that there were increased of flexural and compressive strength at 200°C, and constantly decreased when subjected to 400°C, 700°C and 1000 °C. There were also variation of strengths at different percentages of EPA replacement. Highest compressive strength and flexural strength recorded were both at 200 °C with 65.52 MPa and 21.34 MPa respectively. The study conclude that by using EPA as aggregate replacement was ineffective below elevated temperatures but increased the performance of the mortar at elevated temperatures.
ELECTRONIC CIRCUIT BOARDS NON-UNIFORM COOLING SYSTEM MODEL
Directory of Open Access Journals (Sweden)
D. V. Yevdulov
2016-01-01
Full Text Available Abstract. The paper considers a mathematical model of non-uniform cooling of electronic circuit boards. The block diagram of the system implementing this approach, the method of calculation of the electronic board temperature field, as well as the principle of its thermal performance optimizing are presented. In the considered scheme the main heat elimination from electronic board is produced by the radiator system, and additional cooling of the most temperature-sensitive components is produced by thermoelectric batteries. Are given the two-dimensional temperature fields of the electronic board during its uniform and non-uniform cooling, is carried out their comparison. As follows from the calculations results, when using a uniform overall cooling of electronic unit there is a waste of energy for the cooling 0f electronic board parts which temperature is within acceptable temperature range without the cooling system. This approach leads to the increase in the cooling capacity of used thermoelectric batteries in comparison with the desired values. This largely reduces the efficiency of heat elimination system. The use for electronic boards cooling of non-uniform local heat elimination removes this disadvantage. The obtained dependences show that in this case, the energy required to create a given temperature is smaller than when using a common uniform cooling. In this approach the temperature field of the electronic board is more uniform and the cooling is more efficient.
A Study of Compressive Strength Characteristics of Laterite Sand Hollow Blocks
Directory of Open Access Journals (Sweden)
Abiodun Olanipekun
2007-01-01
Full Text Available This paper presents the results of experimental investigations carried out on partial replacement of sand with laterite as it affects the compressive strength of sandcrete hollow blocks. Two mix proportions (1:6 and 1:8 were used with laterite content varying between 0 and 50% at 10% intervals. Hand and machine compaction methods were used. Curing was done by sprinkling water on the specimens. The results showed that for each mix proportion and compaction method, the compressive strength decreases with increase in laterite content. Machine compacted hollow sandcrete blocks made from mix ratio 1:6 and with up to 10% laterite content is found suitable and hence recommended for building construction having attained a 28-day compressive strength of 2.07N/mm2 as required by the Nigerian Standards.
Energy Technology Data Exchange (ETDEWEB)
Setyawan, Paryanto Dwi, E-mail: paryanto-ds@yahoo.com; Sugiman,; Saputra, Yudhi [Department of Mechanical Engineering, Faculty of Engineering, University of Mataram, Mataram, West Nusa Tenggara (Indonesia)
2016-03-29
The paper presents the compressive and the short beam shear strength of a sandwich composite with opened cell foam made of bamboo fiber as the core and plywood as the skins. The core thickness was varied from 10 mm to 40 mm keeping the volume fraction of fiber constant. Several test s were carried out including the core density, flatwise compressive and the short beam shear testing in three point bending. The results show that the density of bamboo opened cell foam is comparable with commercial plastic foam, such as polyurethane foam. The compressive strength tends to increase linearly with increasing the core thickness. The short beam shear failure load of the sandwich composite increases with the increase of core thickness, however on the contrary, the short beam shear strength which tends to sharply decrease from the thickness of 10 mm to 30 mm and then becomes flat.
Effects of densified silica fume on microstructure and compressive strength of blended cement pastes
International Nuclear Information System (INIS)
Ji Yajun; Cahyadi, Jong Herman
2003-01-01
Some experimental investigations on the microstructure and compressive strength development of silica fume blended cement pastes are presented in this paper. The silica fume replacement varies from 0% to 20% by weight and the water/binder ratio (w/b) is 0.4. The pore structure by mercury intrusion porosimetry (MIP), the micromorphology by scanning electron microscopy (SEM) and the compressive strength at 3, 7, 14, 28, 56 and 90 days have been studied. The test results indicate that the improvements on both microstructure and mechanical properties of hardened cement pastes by silica fume replacement are not effective due to the agglomeration of silica fume particles. The unreacted silica fume remained in cement pastes, the threshold diameter was not reduced and the increase in compressive strength was insignificant up to 28 days. It is suggested that the proper measures should be taken to disperse silica fume agglomeration to make it more effective on improving the properties of materials
The effects of shelf life on the compressive strength of resin-modified glass ionomer cement
Wajong, K. H.; Damiyanti, M.; Irawan, B.
2017-08-01
Resin-modified glass ionomer cement (RMGIC) is a restoration material composed of powder and liquid whose stability is affected by its shelf life. This is an issue that has not been taken into consideration by customers or sellers. To observe the effects of shelf life on the compressive strength of RMGIC, 30 cylindrical (d = 4mm and t = 6mm) specimens of RMGIC (Fuji II LC, GC, Tokyo, Japan) were divided into three groups with different storage times and their compressive strength was tested with a universal testing machine. Results were statistically analyzed with the one-way ANOVA test. There were significant differences (p<0.05) between the three groups of RMGIC. There is a decrease in the compressive strength value along with the duration of storage time.
An investigation of the compressive strength of Kevlar 49/epoxy composites
Kulkarni, S. V.; Rosen, B. W.; Rice, J. S.
1975-01-01
Tests were performed to evaluate the effect of a wide range of variables including matrix properties, interface properties, fiber prestressing, secondary reinforcement, and others on the ultimate compressive strength of Kevlar 49/epoxy composites. Scanning electron microscopy is used to assess the resulting failure surfaces. In addition, a theoretical study is conducted to determine the influence of fiber anisotropy and lack of perfect bond between fiber and matrix on the shear mode microbuckling. The experimental evaluation of the effect of various constituent and process characteristics on the behavior of these unidirectional composites in compression did not reveal any substantial increase in strength. However, theoretical evaluations indicate that the high degree of fiber anisotropy results in a significant drop in the predicted stress level for internal instability. Scanning electron microscope data analysis suggests that internal fiber failure and smooth surface debonding could be responsible for the measured low compressive strengths.
Statistical approach to predict compressive strength of high workability slag-cement mortars
International Nuclear Information System (INIS)
Memon, N.A.; Memon, N.A.; Sumadi, S.R.
2009-01-01
This paper reports an attempt made to develop empirical expressions to estimate/ predict the compressive strength of high workability slag-cement mortars. Experimental data of 54 mix mortars were used. The mortars were prepared with slag as cement replacement of the order of 0, 50 and 60%. The flow (workability) was maintained at 136+-3%. The numerical and statistical analysis was performed by using database computer software Microsoft Office Excel 2003. Three empirical mathematical models were developed to estimate/predict 28 days compressive strength of high workability slag cement-mortars with 0, 50 and 60% slag which predict the values accurate between 97 and 98%. Finally a generalized empirical mathematical model was proposed which can predict 28 days compressive strength of high workability mortars up to degree of accuracy 95%. (author)
Effect of In-Situ Curing on Compressive Strength of Reactive Powder Concrete
Directory of Open Access Journals (Sweden)
Bali Ika
2016-01-01
Full Text Available A development of Reactive Powder Concrete (RPC currently is the use of quartz powder as a stabilizing agent with the content to cement ratio of 30% and steam curing method in an autoclave temperature of 250ºC which produced a high compressive strength of 180 MPa. That RPC can be generated due to one reason for using the technique of steam curing in an autoclave in the laboratory. This study proposes in-situ curing method in order the curing can be applied in the field and with a reasonable compressive strength results of RPC. As the benchmarks in this study are the curing methods in laboratory that are steam curing of 90°C for 8 hours (C1, and water curing for 28 days (C2. For the in-situ curing methods that are covering with tarpaulins and flowed steam of 3 hours per day for 7 days (C3, covering with wet sacks for 28 days (C4, and covering with wet sacks for 28 days for specimen with unwashed sand as fine aggregate (C5. The comparison of compressive strength of the specimens in this study showed compressive strength of RPC with in-situ steam curing (101.64 MPa close to the compressive strength of RPC with steam curing in the laboratory with 8.2% of different. While in-situ wet curing compared with the water curing in laboratory has the different of 3.4%. These results indicated that the proposed in-situ curing methods are reasonable good in term of the compressive strength that can be achieved.
Evaluation of the Compressive Strength of Cement-Spent Resins Matrix Mixed with Bio char
International Nuclear Information System (INIS)
Zalina Laili; Muhamad Samudi Yasir; Zalina Laili; Mohd Abdul Wahab; Nur Azna Mahmud; Nurfazlina Zainal Abidin
2015-01-01
The evaluation of compressive strength of cement-spent resins matrix mixed with bio char was investigated. In this study, bio char with different percentage (5 %, 8 %, 11 % 14 % and 18 %) was used as alternative admixture material for cement solidification of spent resins. Some properties of the physical and chemical of spent resins and bio char were also investigated. The performance of cemented spent resins with the addition of bio char was evaluated based on their compressive strength and the water resistance test. The compressive strength was evaluated at three different curing periods of 7, 14 and 28 days, while 4 weeks of immersion in distilled water was chosen for water resistance test. The result indicated that the compressive strength at 7, 14 and 28 days of curing periods were above the minimum criterion for example > 3.45 MPa of acceptable level for cemented waste form. Statistical analysis showed that there was no significant relationship between the compressive strength of the specimen and the percentage of bio char content. Result from the water resistance test showed that only one specimen that contained of 5 % of bio char failed the water resistance test due to the high of spent resins/ bio char ratio. The compressive strength of cement solidified spent resins was found increased after the water resistance test indicating further hydration occurred after immersed in water. The results of this study also suggest that the specimen with 8 %, 11 %, 14 % and 18 % of bio char content were resistance in water and suitable for the leaching study of radionuclides from cement-bio char-spent resins matrix. (author)
International Nuclear Information System (INIS)
Ranjbar, Navid; Mehrali, Mehdi; Behnia, Arash; Alengaram, U. Johnson; Jumaat, Mohd Zamin
2014-01-01
Highlights: • Results show POFA is adaptable as replacement in FA based geopolymer mortar. • The increase in POFA/FA ratio delay of the compressive development of geopolymer. • The density of POFA based geoploymer is lower than FA based geopolymer mortar. - Abstract: This paper presents the effects and adaptability of palm oil fuel ash (POFA) as a replacement material in fly ash (FA) based geopolymer mortar from the aspect of microstructural and compressive strength. The geopolymers developed were synthesized with a combination of sodium hydroxide and sodium silicate as activator and POFA and FA as high silica–alumina resources. The development of compressive strength of POFA/FA based geopolymers was investigated using X-ray florescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and field emission scanning electron microscopy (FESEM). It was observed that the particle shapes and surface area of POFA and FA as well as chemical composition affects the density and compressive strength of the mortars. The increment in the percentages of POFA increased the silica/alumina (SiO 2 /Al 2 O 3 ) ratio and that resulted in reduction of the early compressive strength of the geopolymer and delayed the geopolymerization process
International Nuclear Information System (INIS)
Wongkeo, Watcharapong; Thongsanitgarn, Pailyn; Pimraksa, Kedsarin; Chaipanich, Arnon
2012-01-01
Highlights: ► Autoclaved aerated concrete were produced using coal bottom ash as a cement replacement material. ► Coal bottom ash was found to enhance concrete strengths. ► Thermal conductivity of concrete was not significantly affected. ► X-ray diffraction and thermal analysis show tobermorite formation. -- Abstract: The bottom ash (BA) from Mae Moh power plant, Lampang, Thailand was used as Portland cement replacement to produce lightweight concrete (LWC) by autoclave aerated concrete method. Portland cement type 1, river sand, bottom ash, aluminium powder and calcium hydroxide (Ca(OH) 2 ) were used in this study. BA was used to replace Portland cement at 0%, 10%, 20% and 30% by weight and aluminium powder was added at 0.2% by weight in order to produce the aerated concrete. Compressive strength, flexural and thermal conductivity tests were then carried out after the concrete were autoclaved for 6 h and left in air for 7 days. The results show that the compressive strength, flexural strength and thermal conductivity increased with increased BA content due to tobermorite formation. However, approximately, 20% increase in both compressive (up to 11.61 MPa) and flexural strengths (up to 3.16 MPa) was found for mixes with 30% BA content in comparison to just around 6% increase in the thermal conductivity. Thermogravimetry analysis shows C–S–H formation and X-ray diffraction confirm tobermorite formation in bottom ash lightweight concrete. The use of BA as a cement replacement, therefore, can be seen to have the benefit in enhancing strength of the aerated concrete while achieving comparatively low thermal conductivity when compared to the results of the control Portland cement concrete.
The statitistical evaluation of the uniaxial compressive strength of the Ruskov andesite
Directory of Open Access Journals (Sweden)
Krepelka František
2002-03-01
Full Text Available The selection of a suitable model of the statistical distribution of the uniaxial compressive strength is discussed in the paper. The uniaxial compressive strength was studied on 180 specimens of the Ruskov andesite. The rate of loading was 1MPa.s-1. The experimental specimens had a prismatic form with a square base; the slightness ratio of specimens was 2:1. Three sets of specimens with a different length of the base edge were studied, namely 50, 30 and 10 mm. The result of the measurement were three sets with 60 values of the uniaxial compressive strength. The basic statistical parameters: the sample mean, the sample standard deviation, the variational interval, the minimum and maximum value, the sample obliqueness coefficient and the sharpness coefficient were evaluated for each collection. Two types of the distribution which can be joined with the real physical fundamentals of the desintegration of rocks ( the normal and the Weibull distribution were tested. The two-parametric Weibull distribution was tested. The basic characteristics of both distributions were evaluated for each set and the accordance of the model distribution with an experimental distribution was tested. The ÷2-test was used for testing. The two-parametric Weibull distribution was selected following the comparison of the test results of both model distributions as a suitable distribution model for the characterization of uniaxial compressive strength of the Ruskov andesite. The two-parametric Weibull distribution showed better results of the goodness-of-fit test. The normal distribution was suitable for two sets; one of the sets showed a negative result of the goodness-of-fit testing. At the uniaxial compressive strength of the Ruskov andesite, a scale effect was registered : the mean value of uniaxial compressive strength decreases with increasing the specimen base edge. This is another argument for using the Weibull distribution as a suitable statistical model of the
International Nuclear Information System (INIS)
Biggemann, M.; Hilweg, D.; Seidel, S.; Horst, M.; Brinckmann, P.
1991-01-01
Vertebral insufficiency fractures may result from excessive loading of normal and routine loading of osteoporotic spines. Fractures occur when the mechanical load exceeds the vertebral compressive strength, i.e., the maximum load a vertebra can tolerate. Vertebral compressive strength is determined by trabecular bone density and the size of end-plate area. Both parameters can be measured non-invasively by quanti-tative computed tomography (QCT). In 75 patients compressive strength (i.e., trabecular bone density and endplate area) of the vertebra L3 was determined using QCT. In addition, conventional radiographs of the spines were analysed for the prevalence of insufficiency fractures in each case. By relating fracture prevalence to strength, 3 fracture risk groups were found: a high-risk group with strength values of L3 5 kN and a fracture risk near 0 percent. Biomechanical measurements and model calculations indicate that spinal loads of 3 to 4 kN at L3/4 will be common in everyday activities. These data and the results described above suggest that spines with strength values of L3<3 kN are at an extremely high risk of insufficiency fractures in daily life. Advantages of fracture risk assessment by strength determination over risk estimation based on clinically used trabecular bone density measurements are discussed. (author). 18 refs.; 4 figs
Reynolds, Gavin K; Campbell, Jacqueline I; Roberts, Ron J
2017-10-05
A new model to predict the compressibility and compactability of mixtures of pharmaceutical powders has been developed. The key aspect of the model is consideration of the volumetric occupancy of each powder under an applied compaction pressure and the respective contribution it then makes to the mixture properties. The compressibility and compactability of three pharmaceutical powders: microcrystalline cellulose, mannitol and anhydrous dicalcium phosphate have been characterised. Binary and ternary mixtures of these excipients have been tested and used to demonstrate the predictive capability of the model. Furthermore, the model is shown to be uniquely able to capture a broad range of mixture behaviours, including neutral, negative and positive deviations, illustrating its utility for formulation design. Copyright © 2017 Elsevier B.V. All rights reserved.
Temperature and moisture content effects on compressive strength parallel to the grain of paricá
Directory of Open Access Journals (Sweden)
Manuel Jesús Manríquez Figueroa
Full Text Available The aim of this study is to evaluate the effect of the temperature and moisture content on the compressive strength parallel to the grain of paricá (Schizolobium amazonicum Huber ex. Ducke from cultivated forests. The experiments were carried out on 3 timber samples under different conditions: heated (HT, thermal treatment (TT and water saturated (WS. The HT sample consisted of 105 clear specimens assembled in 15 groups, the TT consisted of 90 clear specimens assembled in 15 groups and the WS consisted of 90 clear specimens assembled in 9 groups. The specimens from HT and WS samples were tested at a temperature range from 20 to 230 ºC and 20 to 100 ºC, respectively. The HT specimens were tested at ambient temperature, but after being submitted to thermal treatment. The HT, TT and WS samples present a decrease in the compressive strength, reaching 65%, 76% and 59% of the compressive strength at room temperature, respectively. The decrease in the compressive strength of the HT and WS samples can be associated to the thermal degradation of wood polymers and the moisture content. For the TT sample, the strength increased for a pre-heating temperature of up to 170 °C due to the reduction in the moisture content of the specimens.
International Nuclear Information System (INIS)
Wan Khairuddin bin Wan Ali
1994-01-01
An investigation was carried out to determine and compile the mechanical strength of a refractory ceramic made of ground fire bricks and refractory fire mortar. Three different compositions were studied for the compression strength and it was found that the composition with 50% fire bricks and 50% fire mortar gives the best mechanical strength. With this composition the maximum failure compression stress is 3.2 MPa. and the Young Modulus is 403.5 MPa. The investigation also shows that the curing temperatures and the composition percentages play an important role in determining the strength of the ceramic. The trend obtained from the investigation shows that there is the possibility that an optimum value of composition percentage exist
Mydin M.A.O.; Sani N. Md.; Mohd Yusoff M.A.; Ganesan S.
2014-01-01
This study investigated the performance of the properties of foamed concrete in replacing volumes of cement of 10%, 15% and 20% by weight. A control unit of foamed concrete mixture made with ordinary Portland cement (OPC) and 10%, 15% and 20% silica fume was prepared. Three mechanical property parameters were studied such as compressive strength, flexural strength and splitting tensile of foamed concrete with different percentages of silica fume. Silica fume is commonly used to increase the m...
Evaluation of Early-Age Concrete Compressive Strength with Ultrasonic Sensors.
Yoon, Hyejin; Kim, Young Jin; Kim, Hee Seok; Kang, Jun Won; Koh, Hyun-Moo
2017-08-07
Surface wave velocity measurement of concrete using ultrasonic sensors requires testing on only one side of a member. Thus, it is applicable to concrete cast inside a form and is often used to detect flaws and evaluate the compressive strength of hardened concrete. Predicting the in situ concrete strength at a very early stage inside the form helps with determining the appropriate form removal time and reducing construction time and costs. In this paper, the feasibility of using surface wave velocities to predict the strength of in situ concrete inside the form at a very early stage was evaluated. Ultrasonic sensors were used to measure a series of surface waves for concrete inside a form in the first 24 h after placement. A continuous wavelet transform was used to compute the travel time of the propagating surface waves. The cylindrical compressive strength and penetration resistance tests were also performed during the test period. Four mixtures and five curing temperatures were used for the specimens. The surface wave velocity was confirmed to be applicable to estimating the concrete strength at a very early age in wall-like elements. An empirical formula is proposed for evaluating the early-age compressive strength of concrete considering the 95% prediction intervals.
International Nuclear Information System (INIS)
Wang, H.M.; Jiang, J.S.; Huang, Z.Y.; Chen, Y.; Liu, K.; Lu, Z.W.; Qi, J.Q.; Li, F.; He, D.W.; Lu, T.C.; Wang, Q.Y.
2016-01-01
Nano-grained ceramics have their unique mechanical characteristics that are not commonly found in their coarse-grained counterparts. In this study, nano-grained YAG transparent ceramics (NG-YAG) were prepared by low-temperature high-pressure technique (LTHP). The peak profile analysis of the X-ray diffraction was employed to investigate the compressive yield strength of NG-YAG. During the temperature at 450 °C, the residual micro-strain (RMS) increased with increasing loading pressure. However when the loading pressure was exceeded to 4.0 GPa the RMS exhibited a severe negative slop. The temperature effects on the compressive yield strength were also studied. It shows that the compressive yield strength of NG-YAG is 4.0 GPa and 5.0 GPa respectively at 450 °C and 350 °C. More importantly according to this investigation, a feasible technique to study the nano-grained ceramics is provided. - Graphical abstract: Fig. 2 shows the significant slope changes of calculated residual micro-strain (RMS) associated with five selected pressure-temperature conditions. Another the grain size estimated from Scherrer's formula, especially when it changes with the pressure-temperature condition is also plotted in Fig. 2. - Highlights: • Prepared the nano-grained YAG transparent ceramic by high pressure technique. • Obtained the compressive yield with different temperature. • Obtained the compressive yield of nano-grained YAG transparent ceramic.
The demagnetizing field of a non-uniform rectangular prism
DEFF Research Database (Denmark)
Smith, Anders; Nielsen, Kaspar Kirstein; Christensen, Dennis
2010-01-01
The effect of demagnetization on the magnetic properties of a rectangular ferromagnetic prism under non-uniform conditions is investigated. A numerical model for solving the spatially varying internal magnetic field is developed, validated and applied to relevant cases. The demagnetizing field...... is solved by an analytical calculation and the coupling between applied field, the demagnetization tensor field and spatially varying temperature is solved through iteration. We show that the demagnetizing field is of great importance in many cases and that it is necessary to take into account the non...
Effect of rice husk ash and fly ash on the compressive strength of high performance concrete
Van Lam, Tang; Bulgakov, Boris; Aleksandrova, Olga; Larsen, Oksana; Anh, Pham Ngoc
2018-03-01
The usage of industrial and agricultural wastes for building materials production plays an important role to improve the environment and economy by preserving nature materials and land resources, reducing land, water and air pollution as well as organizing and storing waste costs. This study mainly focuses on mathematical modeling dependence of the compressive strength of high performance concrete (HPC) at the ages of 3, 7 and 28 days on the amount of rice husk ash (RHA) and fly ash (FA), which are added to the concrete mixtures by using the Central composite rotatable design. The result of this study provides the second-order regression equation of objective function, the images of the surface expression and the corresponding contours of the objective function of the regression equation, as the optimal points of HPC compressive strength. These objective functions, which are the compressive strength values of HPC at the ages of 3, 7 and 28 days, depend on two input variables as: x1 (amount of RHA) and x2 (amount of FA). The Maple 13 program, solving the second-order regression equation, determines the optimum composition of the concrete mixture for obtaining high performance concrete and calculates the maximum value of the HPC compressive strength at the ages of 28 days. The results containMaxR28HPC = 76.716 MPa when RHA = 0.1251 and FA = 0.3119 by mass of Portland cement.
Prediction of Corrosion Resistance of Concrete Containing Natural Pozzolan from Compressive Strength
al-Swaidani, A. M.; Ismat, R.; Diyab, M. E.; Aliyan, S. D.
2015-11-01
A lot of Reinforced Concrete (RC) structures in Syria have suffered from reinforcement corrosion which shortened significantly their service lives. Probably, one of the most effective approaches to make concrete structures more durable and concrete industry on the whole - more sustainable is to substitute pozzolan for a portion of Portland cement (PC). Syria is relatively rich in natural pozzolan. In the study, in order to predict the corrosion resistance from compressive strength, concrete specimens were produced with seven cement types: one plain Portland cement (control) and six natural pozzolan-based cements with replacement levels ranging from 10 to 35%. The development of the compressive strengths of concrete cube specimens with curing time has been investigated. Chloride penetrability has also been evaluated for all concrete mixes after three curing times of 7, 28 and 90 days. The effect on resistance of concrete against damage caused by corrosion of the embedded reinforcing steel has been investigated using an accelerated corrosion test by impressing a constant anodic potential for 7, 28 and 90 days curing. Test results have been statistically analysed and correlation equations relating compressive strength and corrosion performance have been developed. Significant correlations have been noted between the compressive strength and both rapid chloride penetrability and corrosion initiation times. So, this prediction could be reliable in concrete mix design when using natural pozzolan as cement replacement.
Compressive strength of different brands of cement (OPC) in province of Sindh
International Nuclear Information System (INIS)
Khaskheli, G.B.; Kumar, A.; Sheikh, A.
2009-01-01
OPC (Ordinary Portland Cement) is the most common type of cement used in construction industry. Three major brands of OPC are normal OPC, SRC (Sulphate Resisting Cement) and SC (Slag Cement). It is seen that the variation in constituents of cement may cause serious effects on the quality of cement. Thus the motivation of this research is to study the basic properties (consistency, setting time, and fineness), compressive strength (cement mortar and concrete cubes) and modulus of elasticity of all the OPC brands (OPC, SRC and SC) manufactured in Sindh. In total 10 cement factories, altogether 21 different brands of cement, were studied in the light of BS and ASTM Code specifications. In total 126 mortar cubes (1:3), 252 concrete cubes (126 for 3000 psi mix design and remaining for 5000 psi) and 126 concrete cylinders (6 for the each brand of cement pertaining to 3000 psi and 5000 psi mix design) were manufactured and tested. Experimental results demonstrated that all the cement brands fulfilled the BS and ASTM Code requirements for (i) basic properties (ii) compressive strength of mortar cubes at 3 and 28 days curing age (iii) compressive strength of concrete cubes at 28 days curing age, and (iv) modulus of elasticity. Some of the cements did not fulfill the BS and ASTM Code requirements for compressive strength of concrete cubes at 7 days curing age. (author)
The use of non-destructive tests to estimate Self-compacting concrete compressive strength
Directory of Open Access Journals (Sweden)
Djamila Boukhelkhal
2018-01-01
Full Text Available Until now, there are few studies on the effect of mineral admixtures on correlation between compressive strength and ultrasonic pulse velocity for concrete. The aim of this work is to study the effect of mineral admixture available in Algeria such as limestone powder, granulated slag and natural pozzolana on the correlation between compressive strength and corresponding ultrasonic pulse velocity for self-compacting concrete (SCC. Compressive strength and ultrasonic pulse velocity (UPV were determined for four different SCC (with and without mineral admixture at the 3, 7, 28 and 90 day curing period. The results of this study showed that it is possible to develop a good correlation relationship between the compressive strength and the corresponding ultrasonic pulse velocity for all SCC studied in this research and all the relationships had exponential form. However, constants were different for each mineral admixture type; where, the best correlation was found in the case of SCC with granulated slag (R2 = 0.85. Unlike the SCC with pozzolana, which have the lowest correlation coefficient (R2 = 0.69.
Effect of different dispersants in compressive strength of carbon fiber cementitious composites
Lestari, Yulinda; Bahri, Saiful; Sugiarti, Eni; Ramadhan, Gilang; Akbar, Ari Yustisia; Martides, Erie; Khaerudini, Deni S.
2013-09-01
Carbon Fiber Cementitious Composites (CFCC) is one of the most important materials in smart concrete applications. CFCC should be able to have the piezoresistivity properties where its resistivity changes when there is applied a stress/strain. It must also have the compressive strength qualification. One of the important additives in carbon fiber cementitious composites is dispersant. Dispersion of carbon fiber is one of the key problems in fabricating piezoresistive carbon fiber cementitious composites. In this research, the uses of dispersants are methylcellulose, mixture of defoamer and methylcellulose and superplasticizer based polycarboxylate. The preparation of composite samples is similar as in the mortar technique according to the ASTM C 109/109M standard. The additives material are PAN type carbon fibers, methylcellulose, defoamer and superplasticizer (as water reducer and dispersant). The experimental testing conducts the compressive strength and resistivity at various curing time, i.e. 3, 7 and 28 days. The results obtained that the highest compressive strength value in is for the mortar using superplasticizer based polycarboxylate dispersant. This also shown that the distribution of carbon fiber with superplasticizer is more effective, since not reacting with the cementitious material which was different from the methylcellulose that creates the cement hydration reaction. The research also found that the CFCC require the proper water cement ratio otherwise the compressive strength becomes lower.
Directory of Open Access Journals (Sweden)
Ali Ateş
2013-01-01
Full Text Available Soil stabilization has been widely used as an alternative to substitute the lack of suitable material on site. The use of nontraditional chemical stabilizers in soil improvement is growing daily. In this study a laboratory experiment was conducted to evaluate the effects of waterborne polymer on unconfined compression strength and to study the effect of cement grout on pre-venting of liquefiable sandy soils. The laboratory tests were performed including grain size of sandy soil, unit weight, ultrasonic pulse velocity, and unconfined compressive strength test. The sand and various amounts of polymer (1%, 2%, 3%, and 4% and cement (10%, 20%, 30%, and 40% were mixed with all of them into dough using mechanical kneader in laboratory conditions. Grouting experiment is performed with a cylindrical mould of mm. The samples were subjected to unconfined compression tests to determine their strength after 7 and 14 days of curing. The results of the tests indicated that the waterborne polymer significantly improved the unconfined compression strength of sandy soils which have susceptibility of liquefaction.
Effects of CuO nanoparticles on compressive strength of self ...
Indian Academy of Sciences (India)
In the present study, the compressive strength, thermal properties and microstructure of self-compacting concrete with different amounts of CuO nanoparticles have been investigated. CuO nanoparticles with an average particle size of 15 nm were added to self-compacting concrete and various properties of the specimens ...
The Effects of Different Curing Methods on the Compressive Strength of Terracrete
Directory of Open Access Journals (Sweden)
O. Alake
2009-01-01
Full Text Available This research evaluated the effects of different curing methods on the compressive strength of terracrete. Several tests that included sieve analysis were carried out on constituents of terracrete (granite and laterite to determine their particle size distribution and performance criteria tests to determine compressive strength of terracrete cubes for 7 to 35 days of curing. Sand, foam-soaked, tank and open methods of curing were used and the study was carried out under controlled temperature. Sixty cubes of 100 × 100 × 100mm sized cubes were cast using a mix ratio of 1 part of cement, 1½ part of latrite, and 3 part of coarse aggregate (granite proportioned by weight and water – cement ratio of 0.62. The result of the various compressive strengths of the cubes showed that out of the four curing methods, open method of curing was the best because the cubes gained the highest average compressive strength of 10.3N/mm2 by the 35th day.
The variability of wood density and compression strength of Norway spruce
Czech Academy of Sciences Publication Activity Database
Horáček, Petr; Fajstavr, Marek; Stojanović, Marko
2017-01-01
Roč. 10, 1-2 (2017), s. 17-26 ISSN 1803-2451 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:86652079 Keywords : Norway spruce * wood density * compression strength * variability Subject RIV: GK - Forestry OBOR OECD: Forestry
Prediction of compressive strength up to 28 days from microstructure of Portland cement
DEFF Research Database (Denmark)
Svinning, K.; Høskuldsson, Agnar; Justnes, H.
2008-01-01
represented by curves from X-ray diffraction analysis and differential thermogravimetric analysis, as well as particle size distributions. PLS gave maximum explained variance in compressive strength at 1, 2, 7 and 28 days of 93%, 90%, 79% and 67%, respectively. The high explained variance makes the prediction...
Yuan, B.; Yu, Q.L.; Brouwers, H.J.H.
2015-01-01
This study investigates the reaction kinetics, the reaction products and the compressive strength of slag activated by ternary activators, namely waterglass, sodium hydroxide and sodium carbonate. Nine mixtures are designed by the Taguchi method considering the factors of sodium carbonate content
Shahrabadi, Hamid; Sayareh, Sina; Sarkardeh, Hamed
2017-12-01
In the present research, effect of silica fume as an additive and oil polluted sands as aggregates on compressive strength of concrete were investigated experimentally. The amount of oil in the designed mixtures was assumed to be constant and equal to 2% of the sand weight. Silica fume accounting for 10%, 15% and 20% of the weight is added to the designed mixture. After preparation and curing, concrete specimens were placed into the three different conditions: fresh, brackish and saltwater environments (submerged in fresh water, alternation of exposed in air & submerged in sea water and submerged in sea water). The result of compressive strength tests shows that the compressive strength of the specimens consisting of silica fume increases significantly in comparison with the control specimens in all three environments. The compressive strength of the concrete with 15% silica fume content was about 30% to 50% higher than that of control specimens in all tested environments under the condition of using polluted aggregates in the designed mixture.
The influence of lay-up and thickness on composite impact damage and compression strength
Guynn, E. G.; Obrien, T. K.
1985-01-01
The effects of composite stacking sequence, thickness, and percentage of zero-degree plies on the size, shape, and distribution of delamination through the laminate thickness and on residual compression strength following impact were studied. Graphite/epoxy laminates were impacted with an 0.5 inch diameter aluminum sphere at a specific low or high velocity. Impact damage was measured nondestructively by ultrasonic C-scans and X-radiography and destructively by the deply technique, and compression strength tests were performed. It was found that differences in compression failure strain due to stacking sequence were small, while laminates with very low percentages of zero-degree plies had similar failure loads but higher failure strains than laminates with higher percentages of zero-degree plies. Failure strain did not correlate with planar impact damage area, and delaminations in impact regions were associated with matrix cracking.
Solikin Mochamad; Setiawan Budi
2017-01-01
High volume fly ash concrete becomes one of alternatives to produce green concrete as it uses waste material and significantly reduces the utilization of Portland cement in concrete production. Although using less cement, its compressive strength is comparable to ordinary Portland cement (hereafter OPC) and the its durability increases significantly. This paper reports investigation on the effect of design strength, fly ash content and curing method on compressive strength of High Volume Fly ...
Optimum Compressive Strength of Hardened Sandcrete Building Blocks with Steel Chips
Directory of Open Access Journals (Sweden)
Alohan Omoregie
2013-02-01
Full Text Available The recycling of steel chips into an environmentally friendly, responsive, and profitable commodity in the manufacturing and construction industries is a huge and difficult challenge. Several strategies designed for the management and processing of this waste in developed countries have been largely unsuccessful in developing countries mainly due to its capital-intensive nature. To this end, this investigation attempts to provide an alternative solution to the recycling of this material by maximizing its utility value in the building construction industry. This is to establish their influence on the compressive strength of sandcrete hollow blocks and solid cubes with the aim of specifying the range percent of steel chips for the sandcrete optimum compressive strength value. This is particularly important for developing countries in sub-Saharan Africa, and even Latin America where most sandcrete blocks exhibit compressive strengths far below standard requirements. Percentages of steel chips relative to the weight of cement were varied and blended with the sand in an attempt to improve the sand grading parameters. The steel chips variations were one, two, three, four, five, ten and fifteen percent respectively. It was confirmed that the grading parameters were improved and there were significant increases in the compressive strength of the blocks and cube samples. The greatest improvement was noticed at four percent steel chips and sand combination. Using the plotted profile, the margin of steel chips additions for the optimum compressive strength was also established. It is recommended that steel chip sandcrete blocks are suitable for both internal load bearing, and non-load bearing walls, in areas where they are not subjected to moisture ingress. However, for external walls, and in areas where they are liable to moisture attack after laying, the surfaces should be well rendered. Below ground level, the surfaces should be coated with a water
Compressive strength of dental composites photo-activated with different light tips
International Nuclear Information System (INIS)
Galvão, M R; Campos, E A; Rastelli, A N S; Andrade, M F; Caldas, S G F R; Calabrez-Filho, S; Bagnato, V S
2013-01-01
The aim of this study was to evaluate the compressive strength of microhybrid (Filtek™ Z250) and nanofilled (Filtek™ Supreme XT) composite resins photo-activated with two different light guide tips, fiber optic and polymer, coupled with one LED. The power density was 653 mW cm −2 when using the fiber optic light tip and 596 mW cm −2 with the polymer. After storage in distilled water at 37 ± 2 °C for seven days, the samples were subjected to mechanical testing of compressive strength in an EMIC universal mechanical testing machine with a load cell of 5 kN and speed of 0.5 mm min −1 . The statistical analysis was performed using ANOVA with a confidence interval of 95% and Tamhane’s test. The results showed that the mean values of compressive strength were not influenced by the different light tips (p > 0.05). However, a statistical difference was observed (p < 0.001) between the microhybrid composite resin photo-activated with the fiber optic light tip and the nanofilled composite resin. Based on these results, it can be concluded that microhybrid composite resin photo-activated with the fiber optic light tip showed better results than nanofilled, regardless of the tip used, and the type of the light tip did not influence the compressive strength of either composite. Thus, the presented results suggest that both the fiber optic and polymer light guide tips provide adequate compressive strength to be used to make restorations. However, the fiber optic light tip associated with microhybrid composite resin may be an interesting option for restorations mainly in posterior teeth. (paper)
Directory of Open Access Journals (Sweden)
Angel Alvarez-Arenal
2016-01-01
Full Text Available The purpose of this study was to evaluate and compare the retention strength of five cement types commonly used in implant-retained fixed partial dentures, before and after compressive cyclic loading. In five solid abutments screwed to 5 implant analogs, 50 metal Cr-Ni alloy copings were cemented with five luting agents: resin-modified glass ionomer (RmGI, resin composite (RC, glass ionomer (GI, resin urethane-based (RUB, and compomer cement (CC. Two tensile tests were conducted with a universal testing machine, one after the first luting of the copings and the other after 100,000 cycles of 100 N loading at 0.72 Hz. The one way ANOVA test was applied for the statistical analysis using the post hoc Tukey test when required. Before and after applying the compressive load, RmGI and RC cement types showed the greatest retention strength. After compressive loading, RUB cement showed the highest percentage loss of retention (64.45%. GI cement recorded the lowest retention strength (50.35 N and the resin composite cement recorded the highest (352.02 N. The type of cement influences the retention loss. The clinician should give preference to lower retention strength cement (RUB, CC, and GI if he envisages any complications and a high retention strength one (RmGI, RC for a specific clinical situation.
Directory of Open Access Journals (Sweden)
Solikin Mochamad
2017-01-01
Full Text Available High volume fly ash concrete becomes one of alternatives to produce green concrete as it uses waste material and significantly reduces the utilization of Portland cement in concrete production. Although using less cement, its compressive strength is comparable to ordinary Portland cement (hereafter OPC and the its durability increases significantly. This paper reports investigation on the effect of design strength, fly ash content and curing method on compressive strength of High Volume Fly Ash Concrete. The experiment and data analysis were prepared using minitab, a statistic software for design of experimental. The specimens were concrete cylinder with diameter of 15 cm and height of 30 cm, tested for its compressive strength at 56 days. The result of the research demonstrates that high volume fly ash concrete can produce comparable compressive strength which meets the strength of OPC design strength especially for high strength concrete. In addition, the best mix proportion to achieve the design strength is the combination of high strength concrete and 50% content of fly ash. Moreover, the use of spraying method for curing method of concrete on site is still recommended as it would not significantly reduce the compressive strength result.
Coefficient αcc in design value of concrete compressive strength
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Goleš Danica
2016-01-01
Full Text Available Coefficient αcc introduces the effects of rate and duration of loading on compressive strength of concrete. These effects may be partially or completely compensated by the increase in concrete strength over time. Selection of the value of this coefficient, in recommended range between 0.8 and 1.0, is carried out through the National Annexes to Eurocode 2. This paper presents some considerations related to the introduction of this coefficient and its value adopted in some European countries. The article considers the effect of the adoption of conservative value αcc=0.85 on design value of compressive and flexural resistance of rectangular cross-section made of normal and high strength concrete. It analyzes the influence of different values of coefficient αcc on the area of reinforcement required to achieve the desired resistance of cross-section.
THE COMPRESSIVE AND FLEXURAL STRENGTHS OF SELF-COMPACTING CONCRETE USING RAW RICE HUSK ASH
Directory of Open Access Journals (Sweden)
MD NOR ATAN
2011-12-01
Full Text Available This study investigates the compressive and flexural strengths of self-compacting concrete incorporating raw rice husk ash, individually and in combination with other types of mineral additives, as partial cement replacement. The additives paired with raw rice husk ash were fine limestone powder, pulverized fuel ash and silica fumes. The mix design was based on the rational method where solid constituents were fixed while water and superplasticizer contents were adjusted to produce optimum viscosity and flowability. All mixes were designed to achieve SF1 class slump-flow with conformity criteria ≥ 520 mm and ≤ 700 mm. Test results show that 15% replacement of cement using raw rice husk ash produced grade 40 concrete. It was also revealed that 30% and 45% cement replacements using raw rice husk ash combined with limestone powder and raw rice husk ash combined with limestone powder and silica fume respectively, produced comparable compressive strength to normal concrete and improved flexural strengths.
DEFF Research Database (Denmark)
Antonio Barbosa, Ricardo; Gustenhoff Hansen, Søren; Hansen, Kurt Kielsgaard
2018-01-01
ASR-damaged flat slab bridges in service. Furthermore, the influence of the ASR-induced crack orientation on the compressive strength and the Young’s modulus is investigated. Uniaxial compression tests, visual observations, and thin section examinations were performed on more than 100 cores drilled...... from the three severely ASR-damaged flat slab bridges. It was found that the orientation of ASR-induced cracks has a significant influence on the uniaxial compressive strength and the stress-strain relationship of the tested cores. The compressive strength in a direction parallel to ASR cracks can...
International Nuclear Information System (INIS)
Fassmann-Glaser, I.
1984-01-01
A study with 25 patients was performed in order to find out whether intermittent, sequential, pneumatic leg compression is of value in the preventive management of thrombosis due to its effect on the venous flow rates. For this purpose, xenon 133 was injected into one of the foot veins and the flow rate in each case determined for the distance between instep and inguen using different compression strengths, with pressure being exerted on the ankle, calf and thigh. Increased flow rates were already measured at an average pressure value of 34.5 mmHg, while the maximum effect was achieved by exerting a pressure of 92.5 mmHg, which increased the flow rate by 366% as compared to the baseline value. The results point to a significant improvement of the venous flow rates due to intermittent, sequential, pneumatic leg compression and thus provide evidence to prove the value of this method in the prevention of hemostasis and thrombosis. (TRV) [de
Influence of uncoated and coated plastic waste coarse aggregates to concrete compressive strength
Directory of Open Access Journals (Sweden)
Purnomo Heru
2017-01-01
Full Text Available The use of plastic waste as coarse aggregates in concrete is part of efforts to reduce environmental pollution. In one hand the use of plastic as aggregates can provide lighter weight of the concrete than concrete using natural aggregates, but on the other hand bond between plastic coarse aggregates and hard matrix give low concrete compressive strength. Improvement of the bond between plastic coarse aggregate and hard matrix through a sand coating to plastic coarse aggregate whole surface is studied. Sand used to coat the plastic aggregates are Merapi volcanic sand which are taken in Magelang. Three mixtures of polypropylene (PP coarse plastic aggregates, Cimangkok river sand as fine aggregates, water and Portland Cement Composite with a water-cement ratio of 0.28, 0.3 and 0.35 are conducted. Compression test are performed on concrete cylindrical specimens with a diameter of 10 cm and a height of 20 cm. The results in general show that concrete specimens using plastic aggregates coated with sand have higher compressive strength compared to those of concrete specimens using plastic aggregates without sand coating. The bond improvement is indirectly indicated by the betterment of concrete compressive strength.
Compressive strength of structural concrete made with locally available coarse aggregates
International Nuclear Information System (INIS)
Kumar, A.; Khaskheli, G.B.
2009-01-01
Quality of CA (Coarse Aggregate) is one of the prime factors to control the quality of concrete. But construction industry of Sindh is not very much bothered about the quality of CA in concrete manufacturing. In Sindh, Hyderabad vicinity is comparatively rich in production of CA. This research is to evaluate the compressive strength of structural concrete made with CA obtained from five different crush plants (Petaro, Parker, Palari, Ghulam Hyder Baloch and Ongar), available in the vicinity of Hyderabad. ln total 360 concrete cubes (150x150x150mm) were manufactured, 72 for each source of CA by keeping 1:2:4 and 1:1.5:3 material ratios. The cubes were manufactured with 0.45 w/c (water cement ratio), 0.5 and 0.55 w/c and tested for compressive strength after 3, 7, 14 and 28 days of curing. Results show that performance of CA obtained from all the five crush plants remained in agreement with BS and ACI Code recommendations. Concrete made with CA obtained from Petaro and Parker gave higher early strength than that of others while concrete made with CA obtained from Petaro, Parker together with Palari gave higher 28th day compressive strength. (author)
Optimum mix for fly ash geopolymer binder based on workability and compressive strength
Arafa, S. A.; Ali, A. Z. M.; Awal, A. S. M. A.; Loon, L. Y.
2018-04-01
The request of concrete is increasing every day for sustaining the necessity of development of structure. The production of OPC not only consumes big amount of natural resources and energy, but also emit significant quantity of CO2 to the atmosphere. Therefore, it is necessary to find alternatives like Geopolymer to make the concrete environment friendly. Geopolymer is an inorganic alumino-silicate compound, produced from fly ash. This paper describes the experimental work conducted by casting 40 geopolymer paste mixes, and was cured at 80°C for 24 h to evaluate the effect of various parameters affecting the workability and compressive strength. Alkaline solution to fly ash ratio and sodium hydroxide (NaOH) concentration were chosen as the key parameters of strength and workability. Laboratory investigation with different percentage of sodium hydroxide concentration and different alkaline liquid to fly ash ratio reveals that the optimum ratios are 10 M, AL/FA=0.5. It has generally been found that the workability decreased and the compressive strength increased with an increase in the concentration of sodium hydroxide solution. However, workability was increased and the compressive strength was decreased with the increase in the ratio of fly ash to alkaline solution.
Evaluation of Compressive Strength and Sorption/Solubility of Four Luting Cements
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Tavangar MS
2017-06-01
Full Text Available Abstract: Statement of Problem: Compressive strength (CS and sorption/solubility of the luting cements are two associated factors. Searching a correlation between sorption/solubility and compressive strength of various luting cements is required. Objectives: To measure the water sorption/solubility, and compressive strength of three resin-based and one conventional glass ionomer (CGI luting cement after 1 and 24 h of immersion in distilled water and to determine if there is any correlation between those properties found. Materials and Methods: Four luting cements were investigated. For each material, 10 disc shaped specimens were prepared for measuring the sorption/solubility. The specimens were cured according to the manufacturer’s instructions, and the sorption/solubility were measured in accordance with the ISO 4049’s. For testing the compression strength, for each material 16 cylindrical specimens were prepared by insertion of cements into a stainless steel split mould. The specimens were cured, divided into groups of 8, and then stored in distilled water at (37 ± 1°C for 1 and 24 h. The test was performed using the universal testing machine, the maximum load was recorded and CS was calculated. The data were analysed using SPSS software version 18. One-way ANOVA, post-hoc Tukey’s test and Pearson’s correlation coefficient were performed. Results: G-CEM had the highest mean CS (153.60± 25.15 and CGI luting had the lowest CS (21.36±5.37 (p 0.05. The lowest mean sorption/solubility value was for RelyXTM U200 and Panavia F, and the highest for CGI luting (all p < 0.001. Conclusions: The compressive strength of all cements did not necessarily increase after 24 h and varied depending on the materials. There was a strong reverse correlation between sorption and CS values after both 1 and 24 h immersion. It may be practical for clinician to use those cements with the less sorption / solubility and more stable compression strength over
Effective electrodiffusion equation for non-uniform nanochannels.
Marini Bettolo Marconi, Umberto; Melchionna, Simone; Pagonabarraga, Ignacio
2013-06-28
We derive a one-dimensional formulation of the Planck-Nernst-Poisson equation to describe the dynamics of a symmetric binary electrolyte in channels whose section is nanometric and varies along the axial direction. The approach is in the spirit of the Fick-Jacobs diffusion equation and leads to a system of coupled equations for the partial densities which depends on the charge sitting at the walls in a non-trivial fashion. We consider two kinds of non-uniformities, those due to the spatial variation of charge distribution and those due to the shape variation of the pore and report one- and three-dimensional solutions of the electrokinetic equations.
Decomposed Photo Response Non-Uniformity for Digital Forensic Analysis
Li, Yue; Li, Chang-Tsun
The last few years have seen the applications of Photo Response Non-Uniformity noise (PRNU) - a unique stochastic fingerprint of image sensors, to various types of digital forensic investigations such as source device identification and integrity verification. In this work we proposed a new way of extracting PRNU noise pattern, called Decomposed PRNU (DPRNU), by exploiting the difference between the physical andartificial color components of the photos taken by digital cameras that use a Color Filter Array for interpolating artificial components from physical ones. Experimental results presented in this work have shown the superiority of the proposed DPRNU to the commonly used version. We also proposed a new performance metrics, Corrected Positive Rate (CPR) to evaluate the performance of the common PRNU and the proposed DPRNU.
Non-Uniform Heat Transfer in Thermal Regenerators
DEFF Research Database (Denmark)
Jensen, Jesper Buch
, a numerical model, which simulates a single-blow operation in a parallel-plate regenerator, was developed and used to model the heat transfer under various conditions. In addition to the modeling of the heat transfer, a series of experiments on passive regenerators with non-uniform, but precisely controlled....... Additionally, the experiments gave real comparative results, whereas the model to a certain degree more served to provide insight to the heat transfer processes taking place inside the regenera- tors, something that would be - if not impossible - then highly impractical to do experimentally. It has been found......This thesis presents investigations on the heat transfer in complex heat ex- changers in general and in regenerative heat exchangers (regenerators) in par- ticular. The motivation for this work is a result of inconsistencies obeserved in the results from a series of experiments on active magnetic...
Restoration of non-uniform exposure motion blurred image
Luo, Yuanhong; Xu, Tingfa; Wang, Ningming; Liu, Feng
2014-11-01
Restoring motion-blurred image is the key technologies in the opto-electronic detection system. The imaging sensors such as CCD and infrared imaging sensor, which are mounted on the motion platforms, quickly move together with the platforms of high speed. As a result, the images become blur. The image degradation will cause great trouble for the succeeding jobs such as objects detection, target recognition and tracking. So the motion-blurred images must be restoration before detecting motion targets in the subsequent images. On the demand of the real weapon task, in order to deal with targets in the complex background, this dissertation uses the new theories in the field of image processing and computer vision to research the new technology of motion deblurring and motion detection. The principle content is as follows: 1) When the prior knowledge about degradation function is unknown, the uniform motion blurred images are restored. At first, the blur parameters, including the motion blur extent and direction of PSF(point spread function), are estimated individually in domain of logarithmic frequency. The direction of PSF is calculated by extracting the central light line of the spectrum, and the extent is computed by minimizing the correction between the fourier spectrum of the blurred image and a detecting function. Moreover, in order to remove the strip in the deblurred image, windows technique is employed in the algorithm, which makes the deblurred image clear. 2) According to the principle of infrared image non-uniform exposure, a new restoration model for infrared blurred images is developed. The fitting of infrared image non-uniform exposure curve is performed by experiment data. The blurred images are restored by the fitting curve.
Effect of Sporosarcina Pasteurii on the strength properties of compressed earth specimens
International Nuclear Information System (INIS)
Bernat-Maso, E.; Gil, L.; Escrig, C.; Barbé, J.; Cortés, P.
2018-01-01
Microbial biodeposition of calcite induction for improving the performance of rammed earth is a research area that must be analysed in a representative environment. This analysis must consider the compaction force, particle size distribution and curing process as production variables. This paper investigates the effects of adding specific bacteria, Sporosarcina Pasteurii, into compressed earth cubes and the effect of production variables. Uniaxial compressive tests and direct shear tests have been conducted for 80 specimens. The results indicate that calcite precipitation interacts with the drying process of clay/silt resulting in reducing the compressive strength, the apparent cohesion and the friction angle. Finally, bacterial activity, which is more likely in samples cured in a high humidity environment, tends to reduce the dilatancy effect. [es
Strength properties and structure of a submicrocrystalline Al-Mg-Mn alloy under shock compression
Petrova, A. N.; Brodova, I. G.; Razorenov, S. V.
2017-06-01
The results of studying the strength of a submicrocrystalline aluminum A5083 alloy (chemical composition was 4.4Mg-0.6Mn-0.11Si-0.23Fe-0.03Cr-0.02Cu-0.06Ti wt % and Al base) under shockwave compression are presented. The submicrocrystalline structure of the alloy was produced in the process of dynamic channel-angular pressing at a strain rate of 104 s-1. The average size of crystallites in the alloy was 180-460 nm. Hugoniot elastic limit σHEL, dynamic yield stress σy, and the spall strength σSP of the submicrocrystalline alloy were determined based on the free-surface velocity profiles of samples during shock compression. It has been established that upon shock compression, the σHEL and σy of the submicrocrystalline alloy are higher than those of the coarse-grained alloy and σsp does not depend on the grain size. The maximum value of σHEL reached for the submicrocrystalline alloy is 0.66 GPa, which is greater than that in the coarse-crystalline alloy by 78%. The dynamic yield stress is σy = 0.31 GPa, which is higher than that of the coarse-crystalline alloy by 63%. The spall strength is σsp = 1.49 GPa. The evolution of the submicrocrystalline structure of the alloy during shock compression was studied. It has been established that a mixed nonequilibrium grain-subgrain structure with a fragment size of about 400 nm is retained after shock compression, and the dislocation density and the hardness of the alloy are increased.
Jagalur Mahalingasharma, Srishaila; Prakash, Parasivamurthy; Vishwanath, K. N.; Jawali, Veena
2017-06-01
This paper presents experimental investigations made on the influence of chemical, physical, morphological and mineralogical properties of mineral admixtures such as fly ash, ground granulate blast furnace slag, metakaoline and micro silica used as a replacement of cement in self compacting concrete on workability and compressive strength. Nineteen concrete mixes were cast by replacing with cement by fly ash or ground granulated blast furnace slag as binary blend at 30%, 40%, 50% and with addition of micro silica and metakaoline at 10% as a ternary blend with fly ash, ground granulated blast furnace slag and obtained results were compare with control mix. Water powder ratio 0.3 and super plasticizer dosage 1% of cementitious material was kept constant for all the mixes. The self compacting concrete tested for slump flow, V-funnel, L-Box, J-Ring, T50, and compressive strength on concrete cube were determined at age of 3, 7, 28, 56, 90 days.
Increasing the compressive strength of portland cement concrete using flat glass powder
Energy Technology Data Exchange (ETDEWEB)
Miranda Junior, Edson Jansen Pedrosa de; Bezerra, Helton de Jesus Costa Leite; Politi, Flavio Salgado; Paiva, Antonio Ernandes Macedo, E-mail: edson.jansen@ifma.edu.br [Instituto Federal de Educacao, Ciencia e Tecnologia do Maranha (IFMA), Sao Luis, MA (Brazil). Dept. de Mecanica e Materiais
2014-08-15
This paper analyzes the compressive strength of Portland cement concrete in response to the incorporation of 5%, 10% and 20% of flat glass powder in place of sand, at w/c (water/cement) ratios of 0.50, 0.55 and 0.58. A statistical analysis of variance (ANOVA) was performed after 7, 14 and 28 days of curing. The compressive strength test results indicate that the concrete containing a w/c ratio of 0.50 can be used for structural applications, regardless of the waste glass content, as can that with a w/c ratio of 0.55 containing 20% of waste glass. We suggest that the use of flat glass powder in place of sand in the above mentioned percentages is feasible for the production of an environmentally appropriate and structurally applicable concrete. However, the concrete's fluidity and void content must be taken into account. (author)
Comparison of Machine Learning Techniques for the Prediction of Compressive Strength of Concrete
Directory of Open Access Journals (Sweden)
Palika Chopra
2018-01-01
Full Text Available A comparative analysis for the prediction of compressive strength of concrete at the ages of 28, 56, and 91 days has been carried out using machine learning techniques via “R” software environment. R is digging out a strong foothold in the statistical realm and is becoming an indispensable tool for researchers. The dataset has been generated under controlled laboratory conditions. Using R miner, the most widely used data mining techniques decision tree (DT model, random forest (RF model, and neural network (NN model have been used and compared with the help of coefficient of determination (R2 and root-mean-square error (RMSE, and it is inferred that the NN model predicts with high accuracy for compressive strength of concrete.
Development of Compressive Failure Strength for Composite Laminate Using Regression Analysis Method
Energy Technology Data Exchange (ETDEWEB)
Lee, Myoung Keon [Agency for Defense Development, Daejeon (Korea, Republic of); Lee, Jeong Won; Yoon, Dong Hyun; Kim, Jae Hoon [Chungnam Nat’l Univ., Daejeon (Korea, Republic of)
2016-10-15
This paper provides the compressive failure strength value of composite laminate developed by using regression analysis method. Composite material in this document is a Carbon/Epoxy unidirection(UD) tape prepreg(Cycom G40-800/5276-1) cured at 350°F(177°C). The operating temperature is –60°F~+200°F(-55°C - +95°C). A total of 56 compression tests were conducted on specimens from eight (8) distinct laminates that were laid up by standard angle layers (0°, +45°, –45° and 90°). The ASTM-D-6484 standard was used for test method. The regression analysis was performed with the response variable being the laminate ultimate fracture strength and the regressor variables being two ply orientations (0° and ±45°)
Research on the compressive strength of basic magnesium salts and cyanide slag solidified body
Tu, Yubo; Han, Peiwei; Ye, Shufeng; Wei, Lianqi; Zhang, Xiaomeng; Fu, Guoyan; Yu, Bo
2018-02-01
The solidification of cyanide slag by using basic magnesium salts could reduce pollution and protect the environment. Experiments were carried out to investigate the effects of age, mixing amount of cyanide slag, water cement ratio and molar ratio of MgO to MgSO4 on the compressive strength of basic magnesium salts and cyanide slag solidified body in the present paper. It was found that compressive strength of solidified body increased with the increase of age, and decreased with the increase of mixing amount of cyanide slag and water cement ratio. The molar ratio of MgO to MgSO4 should be controlled in the range from 9 to 11 when the mixing amount of cyanide slag was larger than 80 mass%.
Development of Compressive Failure Strength for Composite Laminate Using Regression Analysis Method
International Nuclear Information System (INIS)
Lee, Myoung Keon; Lee, Jeong Won; Yoon, Dong Hyun; Kim, Jae Hoon
2016-01-01
This paper provides the compressive failure strength value of composite laminate developed by using regression analysis method. Composite material in this document is a Carbon/Epoxy unidirection(UD) tape prepreg(Cycom G40-800/5276-1) cured at 350°F(177°C). The operating temperature is –60°F~+200°F(-55°C - +95°C). A total of 56 compression tests were conducted on specimens from eight (8) distinct laminates that were laid up by standard angle layers (0°, +45°, –45° and 90°). The ASTM-D-6484 standard was used for test method. The regression analysis was performed with the response variable being the laminate ultimate fracture strength and the regressor variables being two ply orientations (0° and ±45°)
Influence of Fly Ash on the Compressive Strength of Foamed Concrete at Elevated Temperature
Directory of Open Access Journals (Sweden)
Ahmad H.
2014-01-01
Full Text Available Foamed concrete is a lightweight concrete that is widely used in the construction industry recently. This study was carried out to investigate the influence of fly ash as a cement replacement material to the residual compressive strength of foamed concrete subjected to elevated temperature. For this study, the foamed concrete density was fixed at 1300 kg/m3 and the sand-cement ratio and water-cement was set at 1:2 and 0.45, respectively. The samples were prepared and tested at the age of 28 days. Based on the results, it has been found that with 25% inclusion of fly ash, the percentage of compressive strength loss was decreased by 3 – 50%.
Directory of Open Access Journals (Sweden)
Sakshi Gupta
2015-12-01
Full Text Available In this paper, application of fuzzy logic technique using triangular membership function for developing models for predicting compressive strength of concrete with partial replacement of cement with nanosilica has been carried out. For this, the data have been taken from various literatures and help in optimizing the constituents available and reducing cost and efforts in studying design to develop mixes by predefining suitable range for experimenting. The use of nanostructured materials in concrete can add many benefits that are directly related to the durability of various cementitious materials, besides the fact that it is possible to reduce the quantities of cement in the composite. Successful prediction by the model indicates that fuzzy logic could be a useful modelling tool for engineers and research scientists in the area of cement and concrete. Compressive strength values of concrete can be predicted in fuzzy logic models without attempting any experiments in a quite short period of time with tiny error rates.
Determination of composition of pozzolanic waste mixtures with optimized compressive strength
Directory of Open Access Journals (Sweden)
Nardi José Vidal
2004-01-01
Full Text Available The utilization of ceramic wastes with pozzolanic properties along with other compounds for obtaining new materials with cementating properties is an alternative for reducing the environmental pollution. The acceptance of these new products in the market demands minimal changes in mechanical properties according to its utilization. For a variable range of compositional intervals, attempts were made to establish limiting incorporation proportions that assure the achievement of minimum pre-established mechanical strength values in the final product. In this case minimum compressive strength value is 3,000 kPa. A simultaneous association of other properties is also possible.
Effect of Pelletized Coconut Fibre on the Compressive Strength of Foamed Concrete
Mohd Jaini Zainorizuan; Mokhatar Shahrul Niza; Mohd Yusof Ammar Saifuddin; Zulkiply Syurafarina; Abd Rahman Mohd Hadi
2016-01-01
Foamed concrete is a controlled low density ranging from 400kg/m3 to 1800kg/m3, and hence suitable for the construction of buildings and infrastructures. The uniqueness of foamed concrete is does not use aggregates in order to retain low density. Foamed concrete contains only cement, sand, water and foam agent. Therefore, the consumption of cement is higher in producing a good quality and strength of foamed concrete. Without the present of aggregates, the compressive strength of foamed concre...
Energy Technology Data Exchange (ETDEWEB)
Kwon, Seung Hee; Jang, Kyung Pil [Department of Civil and Environmental Engineering, Myongji University, Yongin (Korea, Republic of); Bang, Jin-Wook [Department of Civil Engineering, Chungnam National University, Daejeon (Korea, Republic of); Lee, Jang Hwa [Structural Engineering Research Division, Korea Institute of Construction Technology (Korea, Republic of); Kim, Yun Yong, E-mail: yunkim@cnu.ac.kr [Structural Engineering Research Division, Korea Institute of Construction Technology (Korea, Republic of)
2014-08-15
Highlights: • Compressive strength tests for three concrete mixes were performed. • The parameters of the humidity-adjusted maturity function were determined. • Strength can be predicted considering temperature and relative humidity. - Abstract: This study proposes a method for predicting compressive strength developments in the early ages of concretes used in the construction of nuclear power plants. Three representative mixes with strengths of 6000 psi (41.4 MPa), 4500 psi (31.0 MPa), and 4000 psi (27.6 MPa) were selected and tested under various curing conditions; the temperature ranged from 10 to 40 °C, and the relative humidity from 40 to 100%. In order to consider not only the effect of the temperature but also that of humidity, an existing model, i.e. the humidity-adjusted maturity function, was adopted and the parameters used in the function were determined from the test results. A series of tests were also performed in the curing condition of a variable temperature and constant humidity, and a comparison between the measured and predicted strengths were made for the verification.
Zhang, Zuhua; Wang, Hao
2016-08-01
The pore characteristics of GFCs manufactured in the laboratory with 0-16% foam additions were examined using image analysis (IA) and vacuum water saturation techniques. The pore size distribution, pore shape and porosity were obtained. The IA method provides a suitable approach to obtain the information of large pores, which are more important in affecting the compressive strength of GFC. By examining the applicability of the existing models of predicting compressive strength of foam concrete, a modified Ryshkevitch’s model is proposed for GFC, in which only the porosity that is contributed by the pores over a critical diameter (>100 μm) is considered. This “critical void model” is shown to have very satisfying prediction capability in the studied range of porosity. A compression-modulus model for Portland cement concrete is recommended for predicting the compression modulus elasticity of GFC. This study confirms that GFC have similar pore structures and mechanical behavior as those Portland cement foam concrete and can be used alternatively in the industry for the construction and insulation purposes.
Quantum ratchet effect in a time non-uniform double-kicked model
Chen, Lei; Wang, Zhen-Yu; Hui, Wu; Chu, Cheng-Yu; Chai, Ji-Min; Xiao, Jin; Zhao, Yu; Ma, Jin-Xiang
2017-07-01
The quantum ratchet effect means that the directed transport emerges in a quantum system without a net force. The delta-kicked model is a quantum Hamiltonian model for the quantum ratchet effect. This paper investigates the quantum ratchet effect based on a time non-uniform double-kicked model, in which two flashing potentials alternately act on a particle with a homogeneous initial state of zero momentum, while the intervals between adjacent actions are not equal. The evolution equation of the state of the particle is derived from its Schrödinger equation, and the numerical method to solve the evolution equation is pointed out. The results show that quantum resonances can induce the ratchet effect in this time non-uniform double-kicked model under certain conditions; some quantum resonances, which cannot induce the ratchet effect in previous models, can induce the ratchet effect in this model, and the strengths of the ratchet effect in this model are stronger than those in previous models under certain conditions. These results enrich people’s understanding of the delta-kicked model, and provides a new optional scheme to control the quantum transport of cold atoms in experiment.
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Gołaszewski Jacek
2017-06-01
Full Text Available The rheological properties of fresh ordinary concrete are closely affected by temperature and time. The paper presents the study of consistency of fresh concrete mixtures made with Portland cement and cement with calcareous fly ash. Two types of admixtures were used. It was proven that the temperature has a clear effect on workability and compressive strength concrete. Influence on workability can be reduced by selecting the appropriate superplasticizer and cement.
Calcium Lactate addition in Bioconcrete: Effect on Compressive strength and Water penetration
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Irwan J.M
2016-01-01
Full Text Available This paper presents compressive strength and water penetration of bioconcrete with addition of calcium lactate. Bioconcrete has higher engineering concrete properties and durability compared to normal concrete but the natural production of calcium carbonate is limited to the calcium content in cement. Therefore, additional calcium is added as an additional calcium source to study the influence towards compressive strength and water penetration. The bacteria used in this research are Enterococcus faecalis and Bacillus sp. Calcium lactate was added into concrete mix in concentrations of 0.001mol/l, 0.005mol/l and 0.01mol/l of liquid used. The concentration of bacteria added into the mix is by partial replacement of water used in casting, which are 3% for Enterococcus faecalis and 5% for Bacillus sp. Both compressive strength and water penetration test used cubes of 150mm × 150mm × 150mm. The cubes were tested after 28 days. The result of compressive strength for control is 36 MPa while partial replacement of bacteria yields 38.2 MPa for 3% Enterococcus faecalis and 37.0 MPa for 5% Bacillus sp. Calcium lactate with 0.005 mol/L has the best performance with 42.8 MPa for Enterococcus faecalis and 39.6 MPa for Bacillus sp. Whereas for water penetration, the best concentration of calcium lactate which yielded the lowest water penetration is 0.01 mol/l for both Enterococcus faecalis and Bacillus sp which are 8.7 cm and 8 cm respectively. The addition of calcium lactate into bioconcrete is quite promising for improvement of concrete properties and durability.
Tahia Rabbee; Islam M. Rafizul
2012-01-01
This study depicts the experimental investigations into the effect of organic content on the shear strength and compressibility parameters of reconstituted soil. To these attempts, disturbed soil samples were collected from two selected locations of Khulna region. The reconstituted soil having organic content of 5-35 % were prepared in the laboratory to mix at various proportions of inorganic and organic soil at the water content equal to 1.25 times of liquid limits of collected samples .The ...
Compressive Strength of Concrete made from Natural Fine Aggregate Sources in Minna, Nigeria
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M. Abdullahi
2017-12-01
Full Text Available This work presented an investigation of concrete developed from five fine aggregate sources in Minna, Niger state, Nigeria. Tests conducted on the fine aggregate samples included specific gravity, sieve analysis, bulk density and moisture content. The concrete mix design was done using absolute volume method at various mix proportion of 1:2:4, 1:2:3 and 1:1:2 and water-cement ratios of 0.4, 0.45, 0.5, 0.55 and 0.6. The compressive strengths of concrete were determined at 28-day curing age. Test results revealed that the specific gravities of the aggregate were between 2.60 to 2.70, compacted bulk densities also ranged from 1505.18 to 1701.15kg/m3, loose bulk densities ranged from 1379.32 to 1478.17kg/m3, and moisture content ranged from 0.93 to 2.47%. All the fine aggregate samples satisfied the overall and medium grading limits for natural fine aggregates. The coarse aggregate used fairly followed the grading limit for aggregate size of 20 to 5 mm. The compressive strength of the concrete obtained using the aggregate samples A, B, C, D, and Eall within the ranges of 18.97 to 34.98 N/mm2. Statistical models were developed for the compressive strength of concrete as a function of water-cement ratio for various fine aggregate sources and mix proportions. The models were found to have good predictive the capabilities of the compressive strength of concrete for given water-cement ratio. The properties of fine aggregates and the resulting concrete characteristics showed that all the fine aggregate samples are suitable to be used for concrete production.
Influence of uncoated and coated plastic waste coarse aggregates to concrete compressive strength
Purnomo Heru; Pamudji Gandjar; Satim Madsuri
2017-01-01
The use of plastic waste as coarse aggregates in concrete is part of efforts to reduce environmental pollution. In one hand the use of plastic as aggregates can provide lighter weight of the concrete than concrete using natural aggregates, but on the other hand bond between plastic coarse aggregates and hard matrix give low concrete compressive strength. Improvement of the bond between plastic coarse aggregate and hard matrix through a sand coating to plastic coarse aggregate whole surface is...
Ridzwan, Hendrie Johann Muhamad; Shamsudin, Roslinda; Ismail, Hamisah; Yusof, Mohd Reusmaazran; Hamid, Muhammad Azmi Abdul; Awang, Rozidawati Binti
2018-04-01
In this study, ZrO2 microparticles and γ-Fe2O3 nanoparticles have been added into calcium silicate based cements. The purpose of this experiment was to investigate the compressive strength and magnetic properties of the prepared composite cement. Calcium silicate (CAS) powder was prepared by hydrothermal method. SiO2 and CaO obtained from rice husk ash and limestone respectively were autoclaved at 135 °C for 8 h and sintered at 950°C to obtain CAS powder. SiO2:CaO ratio was set at 45:55. CAS/ZrO2 sample were prepared with varying ZrO2 microparticles concentrations by 0-40 wt. %. Compressive strength value of CAS/ZrO2 cements range from 1.44 to 2.44 MPa. CAS/ZrO2/γ-Fe2O3 sample with 40 wt. % ZrO2 were prepared with varying γ-Fe2O3 nanoparticles concentrations (1-5 wt. %). The additions of γ-Fe2O3 nanoparticles showed up to twofold increase in the compressive strength of the cement. X-Ray diffraction (XRD) results confirm the formation of mixed phases in the produced composite cements. Vibrating sample magnetometer (VSM) analysis revealed that the ferromagnetic behaviour has been observed in CAS/ZrO2/γ-Fe2O3 composite cements.
Dehestani, M; Teimortashlu, E; Molaei, M; Ghomian, M; Firoozi, S; Aghili, S
2017-08-01
In this data article experimental data on the compressive strength, and the durability of styrene and bitumen modified sulfur concrete against acidic water and ignition are presented. The percent of the sulfur cement and the gradation of the aggregates used are according to the ACI 548.2R-93 and ASTM 3515 respectively. For the styrene modified sulfur concrete different percentages of styrene are used. Also for the bitumen modified sulfur concrete, different percentages of bitumen and the emulsifying agent (triton X-100) are utilized. From each batch three 10×10×10 cm cubic samples were casted. One of the samples was used for the compressive strength on the second day of casting, and one on the twenty-eighth day. Then the two samples were put under the high pressure flame of the burning liquid gas for thirty seconds and their ignition resistances were observed. The third sample was put into the acidic water and after twenty eight days immersion in water was dried in the ambient temperature. After drying its compressive strength has been evaluated.
Mesoscopic Numerical Computation of Compressive Strength and Damage Mechanism of Rubber Concrete
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Z. H. Xie
2015-01-01
Full Text Available Evaluations of both macroscopic and mesoscopic strengths of materials have been the topic of a great deal of recent research. This paper presents the results of a study, based on the Walraven equation of the production of a mesoscopic random aggregate structure containing various rubber contents and aggregate sizes. On a mesoscopic scale, the damage mechanism in the rubber concrete and the effects of the rubber content and aggregate-mortar interface on the rubber concrete’s compressive resistance property were studied. The results indicate that the random aggregate structural model very closely approximates the experimental results in terms of the fracture distribution and damage characteristics under uniaxial compression. The aggregate-mortar interface mechanical properties have a substantial impact on the test sample’s strength and fracture distribution. As the rubber content increases, the compressive strength and elastic modulus of the test sample decrease proportionally. This paper presents graphics of the entire process from fracture propagation to structural failure of the test piece by means of the mesoscopic finite-element method, which provides a theoretical reference for studying the damage mechanism in rubber concrete and performing parametric calculations.
Ramani Sujatha, Evangelin; SaiSree, S.; Prabalini, C.; Aysha Farsana, Z.
2017-07-01
The choice of natural fibres for soil stabilization provides an economic, safe and eco-friendly alternative to improve the properties of soil. They are an important step forward toward sustainable development. An attempt was made to study the influence of the random addition of untreated coconut fibres on the short term strength of soil, its stress-strain behavior, compaction characteristics and index properties. The soil selected for the study is a highly compressible clay sample with a liquid limit of 52.5 % and plasticity index of 38 %. The soil has no organic content. The study reveals that the compaction curves tend to shift to the right side, indicating more plastic behavior with the addition of fibres. The addition of fibres also reorient the soil structure to a more dispersed fashion. A significant increase in the unconfined compressive strength is also observed. An increase of nearly 51 % in the unconfined compressive strength is observed at 0.75 % coir inclusion. The stress-strain behavior of the soil shows a shift toward more plastic behavior. The mode of failure of the soil specimen is by cracking and with fibre inclusion, length of the failure cracks is restrained as the fibre tends to hold the cracks together, resulting in shorter cracks, with significant bulging of the specimen at failure.
Influence of aggregate characteristics on the compressive strength of normal weight concrete
International Nuclear Information System (INIS)
Qureshi, M.A.; Aslam, M.
2015-01-01
Experimental investigations on the properties of concrete have been performed around the globe and their correlation is interpreted in relevant design codes. The structural behavior of cement concrete significantly relies on the material resources, properties of the aggregates constituting the concrete and the local construction practice. These factors vary from place to place. Therefore, the compressive strength of concrete prepared from the aggregates available in one locality may not be directly applicable to the other areas. The purpose of this study is to evaluate the Influence of locally available coarse aggregates on the compressive strength of normal weight concrete (NWC) prepared under local environmental conditions of district Khairpur Mir's, Sindh, Pakistan. The coarse aggregates were collected from five different quarries in the vicinity of Khairpur Mir's, Pakistan. In total; 180 cubes were tested. 10 different batches were formed in order to arrange individual characterization of concrete. Each batch was contained of 18 cubes and each quarry contains 2 batches making a total of 36 cube with four different ratios for each quarry. Dry density and compressive strength of concrete was calculated and a comparison is provided as a guideline for the future construction work in the local community. (author)
Haryanto, Y.; Hermanto, N. I. S.; Pamudji, G.; Wardana, K. P.
2017-11-01
One feasible solution to overcome the issue of tire disposal waste is the use of waste tire rubber to replace aggregate in concrete. We have conducted an experimental investigation on the effect of rubber tire waste aggregate in cuboid form on the compressive strength and modulus of elasticity of concrete. The test was performed on 72 cylindrical specimens with the height of 300 mm and diameter of 150 mm. We found that the workability of concrete with waste tire rubber aggregate has increased. The concrete density with waste tire rubber aggregate was decreased, and so was the compressive strength. The decrease of compressive strength is up to 64.34%. If the content of waste tire rubber aggregate is more than 40%, then the resulting concrete cannot be categorized as structural concrete. The modulus of elasticity decreased to 59.77%. The theoretical equation developed to determine the modulus of elasticity of concrete with rubber tire waste aggregate has an accuracy of 84.27%.
Alwahab, Zahraa
2012-07-01
This study investigated the effectiveness of disinfecting solution when incorporated into alginate powder instead of water against some microorganisms and on compressive strength of alginate. For measuring antimicrobial activity of alginate, 60 alginate specimens were prepared and divided into two groups: One with water incorporated in the mix (control) and the other with 0.2% chlorhexidine digluconate incorporated in the mix instead of water. The tested microorganisms were: gram +ve cocci, gram -ve bacilli and yeast (each group 10 samples). For measuring compressive strength, 20 specimens of alginate were divided into two groups: One with water incorporated in the mix (control) and the other with chlorhexidine incorporated in the mix. The statistical analysis of antimicrobial efficacy of alginate was performed with Mann-Whitney U-test, which revealed very high significant difference when comparing among groups (p 0.05). The incorporation of disinfecting agents into impression materials could serve an important role in dental laboratory infection control and it had no adverse effect on compressive strength of the hydrocolloid alginate. The risk of transmitting pathogenic microorganisms to dental laboratories via impression has been considered a topic of importance for a number of years.
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Juban Audrey
2017-01-01
Full Text Available In the pharmaceutical field, tablets are the most common dosage form for oral administration in the world. Among different manufacturing processes, direct compression is widely used because of its economics interest and it is a process which avoids the steps of wet granulation and drying processes. Tablets are composed of at least two ingredients: an active pharmaceutical ingredient (API which is mixed with a diluent. The nature of the powders and the processing conditions are crucial for the properties of the blend and, consequently, strongly influence the mechanical characteristics of tablets. Moreover, tablets have to present a suitable mechanical strength to avoid crumbling or breaking when handling, while ensuring an appropriate disintegration after administration. Accordingly, this mechanical property is an essential parameter to consider. Experimental results showed that proportion of the diluent, fragmentary (DCPA or plastic (MCC, had a large influence on the tensile strength evolution with API content as well as the compression load applied during tableting process. From these results a model was developed in order to predict the tensile strength of binary tablets by knowing the compression pressure. The validity of this model was demonstrated for the two studied systems and a comparison was made with two existing models.
Juban, Audrey; Briançon, Stéphanie; Puel, François; Hoc, Thierry; Nouguier-Lehon, Cécile
2017-06-01
In the pharmaceutical field, tablets are the most common dosage form for oral administration in the world. Among different manufacturing processes, direct compression is widely used because of its economics interest and it is a process which avoids the steps of wet granulation and drying processes. Tablets are composed of at least two ingredients: an active pharmaceutical ingredient (API) which is mixed with a diluent. The nature of the powders and the processing conditions are crucial for the properties of the blend and, consequently, strongly influence the mechanical characteristics of tablets. Moreover, tablets have to present a suitable mechanical strength to avoid crumbling or breaking when handling, while ensuring an appropriate disintegration after administration. Accordingly, this mechanical property is an essential parameter to consider. Experimental results showed that proportion of the diluent, fragmentary (DCPA) or plastic (MCC), had a large influence on the tensile strength evolution with API content as well as the compression load applied during tableting process. From these results a model was developed in order to predict the tensile strength of binary tablets by knowing the compression pressure. The validity of this model was demonstrated for the two studied systems and a comparison was made with two existing models.
Effects of Calcined clay minerals and Silica fume on the compressive strength of concrete
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Abolfazl Soltani
2017-05-01
Full Text Available Pozzolanic materials are well known as potential replacements for cement manufacturing in order to increase compressive strength and improve durability of concrete in different environments and leading to save energy particularly reducing global warming effect. The present study reveals the effect of calcined clay minerals as natural pozzolanic material, separately and in combination with and without silica fume. To achieve this aim, 15 mixed designs with a constant water to cementitious ratio of 0.38 is made. In six mixed designs only metakaolin, zeolite or silica fume and in eight other designs metakaolin and silica fume or zeolite and silica fume have been combined. Mixes containing metakaolin or zeolite with ratio of 10 or 20 percent and silica fume with 7 or 10 percent show significant increasing in compressive strength and improving durability, being valuable replacement for cement (in percentages. In particular, the best practice is attributed to the age of 28 days for compressive strength the replacement of the composition is 10% zeolite with 7% of silica fume and for electrical resistance the replacement of the composition is 10% zeolite with 7% of silica fume.
Investigation of compressive strength of concrete with slag and silica fu
International Nuclear Information System (INIS)
Mostofinejad, D.; Mirtalee, K.; Sadeghi, M.
2002-01-01
Without doubt, concrete has special place in construction of different types of structures, and used as one of the most important materials in construction industry. Today, with development and modernization of human knowledge in construction industry, it is possible to reach h igh performance concrete . Mechanical properties and durability of high performance concrete is quite better than that of conventional concrete. In present, the use of supplementary cementitious materials, mainly silica fume, fly ash and blast furnace slag has become increasingly common for reasons of economy and technical benefits imparted by these materials. The aim of present research is investigation and comparison compressive strength of concrete specimens due to variation of water to cementitious materials ratio (W/C M), silica fume and slag percent and their proportions as cement replacement. Furthermore, it is intended to determine best combination of these materials with cement in concrete (optimum percent) to reach to maximum compressive strength. In the current study, specimens were made in 0.5,0.4 and 0.3 W/C M ratio contained 0,20,35 and 50 percent of slag as cement replacement, where in each slag replacement percent, 0, 5, 10 and 15 percent of of silica fume were used as cement replacement. Results of the current study show that the combination effect of slag and silica fume replacement in concrete leads to the maximum compressive strength in concrete; also there are some optimum percents for replacement of slag and silica fume to cement to get the best results
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Dayo Oluwatoyin AKANBI
2017-06-01
Full Text Available Reliability estimates of unconfined compressive strength values from laboratory results for specimens compacted at British Standard Light (BSLfor compacted quarry dust treated black cotton soil using cement for road sub – base material was developed by incorporating data obtained from Unconfined compressive strength (UCS test gotten from the laboratory test to produce a predictive model. Data obtained were incorporated into a FORTRAN-based first-order reliability program to obtain reliability index values. Variable factors such as water content relative to optimum (WRO, hydraulic modulus (HM, quarry dust (QD, cement (C, Tri-Calcium silicate (C3S, Di-calcium silicate (C2S, Tri-Calcium Aluminate (C3A, and maximum dry density (MDD produced acceptable safety index value of1.0and they were achieved at coefficient of variation (COV ranges of 10-100%. Observed trends indicate that WRO, C3S, C2S and MDD are greatly influenced by the COV and therefore must be strictly controlled in QD/C treated black cotton soil for use as sub-base material in road pavements. Stochastically, British Standard light (BSL can be used to model the 7 days unconfined compressive strength of compacted quarry dust/cement treated black cotton soil as a sub-base material for road pavement at all coefficient of variation (COV range 10 – 100% because the safety index obtained are higher than the acceptable 1.0 value.
Effect of shallow angles on compressive strength of biaxial and triaxial laminates.
Jia, Hongli; Yang, Hyun-Ik
2016-01-01
Biaxial (BX) and triaxial (TX) composite laminates with ±45° angled plies have been widely used in wind turbine blades. As the scale of blades increases, BX and TX laminates with shallow-angled plies (i.e. off-axis ply angle shallow-angled BX and TX laminates are critical considering their locations in a wind turbine blade, and therefore in this study, the uniaxial static compression tests were conducted using BX and TX laminates with angled-plies of ±45°, ±35°, and ±25°, for the purpose of evaluation. On the other hand, Mori-Tanaka mean field homogenization method was employed to predict elastic constants of plies in BX and TX laminates involved in tests; linear regression analyses of experimentally measured ply strengths collected from various sources were then performed to estimate strengths of plies in BX and TX laminates; finally, Tsai-Wu, Hashin, and Puck failure criteria were chosen to predict compressive strengths of BX and TX laminates. Comparison between theoretical predictions and test results were carried out to illustrate the effectiveness of each criterion. The compressive strength of BX laminate decreases as ply angle increases, and the trend was successfully predicted by all three failure criteria. For TX laminates, ±35° angled plies rather than ±45° angled plies led to the lowest laminate compressive strength. Hashin and Puck criteria gave good predictions at certain ply angles for TX laminates, but Tsai-Wu criterion was able to capture the unexpected strength variation of TX laminates with ply angle. It was concluded that the transverse tensile stress in 0° plies of TX laminates, which attains its maximum when the off-axis ply angle is 35°, is the dominant factor in failure determination if using Tsai-Wu criterion. This explains the unexpected strength variation of TX laminates with ply angle, and also indicates that proper selection of ply angle is the key to fully utilizing the advantages of shallow-angled laminates.
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Xiao-Yong Wang
2017-01-01
Full Text Available Limestone is widely used in the construction industry to produce Portland limestone cement (PLC concrete. Systematic evaluations of hydration kinetics, compressive strength development, and carbonation resistance are crucial for the rational use of limestone. This study presents a hydration-based model for evaluating the influences of limestone on the strength and carbonation of concrete. First, the hydration model analyzes the dilution effect and the nucleation effect of limestone during the hydration of cement. The degree of cement hydration is calculated by considering concrete mixing proportions, binder properties, and curing conditions. Second, by using the gel–space ratio, the compressive strength of PLC concrete is evaluated. The interactions among water-to-binder ratio, limestone replacement ratio, and strength development are highlighted. Third, the carbonate material contents and porosity are calculated from the hydration model and are used as input parameters for the carbonation model. By considering concrete microstructures and environmental conditions, the carbon dioxide diffusivity and carbonation depth of PLC concrete are evaluated. The proposed model has been determined to be valid for concrete with various water-to-binder ratios, limestone contents, and curing periods.
Prediction of compression strength of high performance concrete using artificial neural networks
International Nuclear Information System (INIS)
Torre, A; Moromi, I; Garcia, F; Espinoza, P; Acuña, L
2015-01-01
High-strength concrete is undoubtedly one of the most innovative materials in construction. Its manufacture is simple and is carried out starting from essential components (water, cement, fine and aggregates) and a number of additives. Their proportions have a high influence on the final strength of the product. This relations do not seem to follow a mathematical formula and yet their knowledge is crucial to optimize the quantities of raw materials used in the manufacture of concrete. Of all mechanical properties, concrete compressive strength at 28 days is most often used for quality control. Therefore, it would be important to have a tool to numerically model such relationships, even before processing. In this aspect, artificial neural networks have proven to be a powerful modeling tool especially when obtaining a result with higher reliability than knowledge of the relationships between the variables involved in the process. This research has designed an artificial neural network to model the compressive strength of concrete based on their manufacturing parameters, obtaining correlations of the order of 0.94
Non-uniform sampling and wide range angular spectrum method
International Nuclear Information System (INIS)
Kim, Yong-Hae; Byun, Chun-Won; Oh, Himchan; Lee, JaeWon; Pi, Jae-Eun; Heon Kim, Gi; Lee, Myung-Lae; Ryu, Hojun; Chu, Hye-Yong; Hwang, Chi-Sun
2014-01-01
A novel method is proposed for simulating free space field propagation from a source plane to a destination plane that is applicable for both small and large propagation distances. The angular spectrum method (ASM) was widely used for simulating near field propagation, but it caused a numerical error when the propagation distance was large because of aliasing due to under sampling. Band limited ASM satisfied the Nyquist condition on sampling by limiting a bandwidth of a propagation field to avoid an aliasing error so that it could extend the applicable propagation distance of the ASM. However, the band limited ASM also made an error due to the decrease of an effective sampling number in a Fourier space when the propagation distance was large. In the proposed wide range ASM, we use a non-uniform sampling in a Fourier space to keep a constant effective sampling number even though the propagation distance is large. As a result, the wide range ASM can produce simulation results with high accuracy for both far and near field propagation. For non-paraxial wave propagation, we applied the wide range ASM to a shifted destination plane as well. (paper)
Terrestrial carbon cycle affected by non-uniform climate warming
International Nuclear Information System (INIS)
Jianyang Xia; Yiqi Luo; Jiquan Chen; Shilong Piao; Ciais, Philippe; Shiqiang Wan
2014-01-01
Feedbacks between the terrestrial carbon cycle and climate change could affect many ecosystem functions and services, such as food production, carbon sequestration and climate regulation. The rate of climate warming varies on diurnal and seasonal timescales. A synthesis of global air temperature data reveals a greater rate of warming in winter than in summer in northern mid and high latitudes, and the inverse pattern in some tropical regions. The data also reveal a decline in the diurnal temperature range over 51% of the global land area and an increase over only 13%, because night-time temperatures in most locations have risen faster than daytime temperatures. Analyses of satellite data, model simulations and in situ observations suggest that the impact of seasonal warming varies between regions. For example, spring warming has largely stimulated ecosystem productivity at latitudes between 30 degrees and 90 degrees N, but suppressed productivity in other regions. Contrasting impacts of day- and night-time warming on plant carbon gain and loss are apparent in many regions. We argue that ascertaining the effects of non-uniform climate warming on terrestrial ecosystems is a key challenge in carbon cycle research. (authors)
Resource reflecting functor and its application to non-uniformity
Srinivasan, Priyaa Varshinee; Sanders, Barry C.; Cockett, Robin
In this work, we formulate an abstract approach to translate one resource theory to another. We adopt the notion of resource theories as partitioned symmetric monoidal categories and extend this notion by considering resource-reflecting functors between resource theories. A functor F is a structure preserving map and F is said to be resource-reflecting if F (g) being a free transformation implies that the transformation g is also free. Thus, a resource-reflecting functor demonstrates that the existence of a free transformation between two resources in the domain resource theory can be inferred from the existence of a free transformation in the codomain theory. As an example, we construct one such functor from the resource theory of non-uniformity to a resource theory of majorization. Thus, our work lays a foundation for expressing similarities between resource theories and for applying results achieved in one resource theory to another. An abstract approach to the translation between theories enables common patterns to be identified between resource theories thereby reducing the effort of solving the same problem for different theories. BCS appreciates financial support from Alberta Innovates, NSERC, China's 1000 Talent Plan and the IQIM, which is an NSF Physics Frontiers Centre (NSF Grant PHY-1125565) with support of the Gordon and Betty Moore Foundation (GBMF-2644).
Non-Uniform Cathode Emission Studies of a MIG Gun
Marchewka, C. D.; Shapiro, M. A.; Sirigiri, J. R.; Temkin, R. J.
2004-11-01
We present the initial results of the modeling of the effect of emission non-uniformity in 96 kV, 40 A Magnetron Injection Gun (MIG) of a 1.5 MW 110 GHz gyrotron using a 3D gun simulation code. The azimuthal emission nonuniformity can lead to increased mode competition and an overall decreased efficiency of the device [1]. The electron beam is modeled from the cathode to a downstream position where the velocity spread saturates using the AMAZE 3D suite of codes. After bench marking the results of the 3D code with 2D codes such as TRAK2D and EGUN, the emitter was modified to simulate asymmetric emission from the cathode to gain an understanding into the effects of inhomogeneous beam current density on the velocity spread and pitch factor of the electron beam. [1] G. S. Nusinovich, A.N. Vlasov, M. Botton, T. M. Antonsen, Jr., S. Cauffman, K. Felch, ``Effect of the azimuthal inhomogeneity of electron emission on gyrotron operation,'' Phys. Plasmas, vol. 8, no. 7, pp. 3473-3479, 2001
Studying of Compressive, Tensile and Flexural Strength of Concrete by Using Steel Fibers
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Muslim Abdul-Ameer
2016-12-01
Full Text Available This research aims to study the effect of adding steel fibers on the mechanical properties of concrete. Steel fiber has a very significant effect on concrete because it delays the propagation of micro cracks that generate due to loading on concrete members such as beams and slabs, therefore ,it increases the strength of concrete. The steel fiber was used in this study as a percentage of the volume of concrete. Mix proportion was 1: 2:4 (cement: sand: gravel by volume for all mixes and using 0% as (control mix,0.1 %,0.2%,0.5 % and 1.0% of steel fibers, these ratios leads to increase the compressive, tensile ,and flexural strength of concrete, where the improvement in flexural strength was significant
Standard test method for compressive (crushing) strength of fired whiteware materials
American Society for Testing and Materials. Philadelphia
2006-01-01
1.1 This test method covers two test procedures (A and B) for the determination of the compressive strength of fired whiteware materials. 1.2 Procedure A is generally applicable to whiteware products of low- to moderately high-strength levels (up to 150 000 psi or 1030 MPa). 1.3 Procedure B is specifically devised for testing of high-strength ceramics (over 100 000 psi or 690 MPa). 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Huai-Shuai Shang
2012-01-01
Full Text Available An experimental study of C20, C25, C30, C40, and C50 big mobility concrete cubes that came from laboratory and construction site was completed. Nondestructive testing (NDT was carried out using impact rebound hammer (IRH techniques to establish a correlation between the compressive strengths and the rebound number. The local curve for measuring strength of the regression method is set up and its superiority is proved. The rebound method presented is simple, quick, and reliable and covers wide ranges of concrete strengths. The rebound method can be easily applied to concrete specimens as well as existing concrete structures. The final results were compared with previous ones from the literature and also with actual results obtained from samples extracted from existing structures.
Influence of Nanolime and Curing Period on Unconfined Compressive Strength of Soil
Directory of Open Access Journals (Sweden)
Panbarasi Govindasamy
2017-01-01
Full Text Available This paper presents the improvement of the unconfined compressive strength (UCS of soil by mixing different percentages of nanolime and 5% lime with soil. The UCS of treated soil increased significantly over curing time with increasing percentage of nanolime. The optimum results were reached at only 0.5% nanolime admixtures which were much higher than 5% lime admixture. This may be due to higher ability of nanolime to flocculate and agglomerate the soil particles compared with the lime. In addition, the lime could fill only the micropores while nanolime could fill the micro- and nanopores as well. The strength gain is inversely proportional to the remolded moisture content and curing period. However, when the content of nanolime used is larger than 0.5%, nanolime particles are not uniformly dispersed. Therefore, a weak area in the form of voids is created, consequently the homogeneous hydrated microstructure cannot be formed, and finally the strength will decrease.
Particle-in-cell simulations of collisionless magnetic reconnection with a non-uniform guide field
International Nuclear Information System (INIS)
Wilson, F.; Neukirch, T.; Harrison, M. G.; Hesse, M.; Stark, C. R.
2016-01-01
Results are presented of a first study of collisionless magnetic reconnection starting from a recently found exact nonlinear force-free Vlasov–Maxwell equilibrium. The initial state has a Harris sheet magnetic field profile in one direction and a non-uniform guide field in a second direction, resulting in a spatially constant magnetic field strength as well as a constant initial plasma density and plasma pressure. It is found that the reconnection process initially resembles guide field reconnection, but that a gradual transition to anti-parallel reconnection happens as the system evolves. The time evolution of a number of plasma parameters is investigated, and the results are compared with simulations starting from a Harris sheet equilibrium and a Harris sheet plus constant guide field equilibrium.
Influence of Curing Humidity on the Compressive Strength of Gypsum-Cemented Similar Materials
Directory of Open Access Journals (Sweden)
Weiming Guan
2016-01-01
Full Text Available The analogous simulation experiment is widely used in geotechnical and mining engineering. However, systematic errors derived from unified standard curing procedure have been underestimated to some extent. In this study, 140 gypsum-cemented similar material specimens were chosen to study their curing procedure with different relative humidity, which is 10%–15%, 40%, 60%, and 80%, respectively. SEM microstructures and XRD spectra were adopted to detect the correlation between microstructures and macroscopic mechanical strength during curing. Our results indicated that the needle-like phases of similar materials began to develop in the early stage of the hydration process through intersecting with each other and eventually transformed into mat-like phases. Increase of humidity may inhibit the development of needle-like phases; thus the compressive strength changes more smoothly, and the time required for the material strength to reach the peak value will be prolonged. The peak strength decreases along with the increase of humidity while the humidity is higher than 40%; however, the reverse tendency was observed if the humidity was lower than 40%. Finally, we noticed that the material strength usually reaches the peak value when the water content continuously reduces and tends towards stability. Based on the above observation, a curing method determination model and experimental strength predication method for gypsum-cemented similar materials were proposed.
Developing the elastic modulus measurement of asphalt concrete using the compressive strength test
Setiawan, Arief; Suparma, Latif Budi; Mulyono, Agus Taufik
2017-11-01
Elastic modulus is a fundamental property of an asphalt mixture. An analytical method of the elastic modulus is needed to determine the thickness of flexible pavement. It has a role as one of the input values on a stress-strain analysis in the finite element method. The aim of this study was to develop the measurement of the elastic modulus by using compressive strength testing. This research used a set of specimen mold tool and Delta Dimensi software to record strain changes occurring in the proving ring of compression machine and the specimens. The elastic modulus of the five types of aggregate gradation and 2 types of asphalt were measured at optimum asphalt content. Asphalt Cement 60/70 and Elastomer Modified Asphalt (EMA) were used as a binder. Manufacturing success indicators of the specimens used void-in-the-mix (VIM) 3-5 % criteria. The success rate of the specimen manufacturing was more than 76%. Thus, the procedure and the compressive strength test equipment could be used for the measurement of the elastic modulus. The aggregate gradation and asphalt types significantly affected the elastic modulus of the asphalt concrete.
International Nuclear Information System (INIS)
Pfeifle, T.W.; Senseny, P.E.; Mellegard, K.D.
1987-01-01
Eight hydrostatic compression creep tests were performed on crushed salt specimens fabricated from Avery Island dome salt. Following the creep test, each specimen was tested in unconfined compression. The experiments were performed to assess the influence of the following four variables on the consolidation and unconfined strength of crushed salt: grain size distribution, temperature, time, and moisture content. The experiment design comprised a half-fraction factorial matrix at two levels. The levels of each variable investigated were grain size distribution, uniform-graded and well-graded (coefficient of uniformity of 1 and 8); temperature 25 0 C and 100 0 C; time, 3.5 x 10 3 s and 950 x 10 3 s (approximately 60 minutes and 11 days, respectively); and moisture content, dry and wet (85% relative humidity for 24 hours). The hydrostatic creep stress was 10 MPa. The unconfined compression tests were performed at an axial strain rate of 1 x 10 -5 s -1 . Results show that the variables time and moisture content have the greatest influence on creep consolidation, while grain size distribution and, to a somewhat lesser degree, temperature have the greatest influence on total consolidation. Time and moisture content and the confounded two-factor interactions between either grain size distribution and time or temperature and moisture content have the greatest influence on unconfined strength. 7 refs., 7 figs., 11 tabs
Polskoy, Petr; Mailyan, Dmitry; Georgiev, Sergey; Muradyan, Viktor
2018-03-01
The increase of high-rise construction volume or «High-Rise Construction» requires the use of high-strength concrete and that leads to the reduction in section size of structures and to the decrease in material consumption. First of all, it refers to the compressed elements for which, when the transverse dimensions are reduced, their flexibility and deformation increase but the load bearing capacity decreases. Growth in construction also leads to the increase of repair and restoration works or to the strengthening of structures. The most effective method of their strengthening in buildings of «High-Rise Construction» is the use of composite materials which reduces the weight of reinforcement elements and labour costs on execution of works. In this article the results of experimental research on strength and deformation of short compressed reinforced concrete structures, reinforced with external carbon fiber reinforcement, are presented. Their flexibility is λh=10, and the cross-section dimensions ratio b/h is 2, that is 1,5 times more, than recommended by standards in Russia. The following research was being done for three kinds of strained and deformed conditions with different variants of composite reinforcement. The results of the experiment proved the real efficiency of composite reinforcement of the compressed elements with sides ratio equal to 2, increasing the bearing capacity of pillars till 1,5 times. These results can be used for designing the buildings of different number of storeys.
Patil, Suneel G; Sajjan, Mc Suresh; Patil, Rekha
2015-02-01
The luting cements must withstand masticatory and parafunctional stresses in the warm and wet oral environment. Mouth temperature and the temperature of the ingested foods may induce thermal variation and plastic deformation within the cements and might affect the strength properties. The objectives of this study were to evaluate the effect of temperature on the compressive and diametral tensile strengths of two polycarboxylate, a conventional glass ionomer and a resin modified glass ionomer luting cements and, to compare the compressive strength and the diametral tensile strength of the selected luting cements at varying temperatures. In this study, standardized specimens were prepared. The temperature of the specimens was regulated prior to testing them using a universal testing machine at a crosshead speed of 1 mm/min. Six specimens each were tested at 23°C, 37°C and 50°C for both the compressive and diametral tensile strengths, for all the luting cements. All the luting cements showed a marginal reduction in their compressive and diametral tensile strengths at raised temperatures. Fuji Plus was strongest in compression, followed by Fuji I > Poly F > Liv Carbo. Fuji Plus had the highest diametral tensile strength values, followed by Poly F = Fuji I = Liv Carbo, at all temperatures. An increase in the temperature caused no significant reduction in the compressive and diametral tensile strengths of the cements evaluated. The compressive strength of the luting cements differed significantly from one another at all temperatures. The diametral tensile strength of resin modified glass ionomers differed considerably from the other cements, whereas there was no significant difference between the other cements, at all the temperatures.
The Effect of Alkaline Activator Ratio on the Compressive Strength of Fly Ash-Based Geopolymer Paste
Lăzărescu, A. V.; Szilagyi, H.; Baeră, C.; Ioani, A.
2017-06-01
Alkaline activation of fly ash is a particular procedure in which ash resulting from a power plant combined with a specific alkaline activator creates a solid material when dried at a certain temperature. In order to obtain desirable compressive strengths, the mix design of fly ash based geopolymer pastes should be explored comprehensively. To determine the preliminary compressive strength for fly ash based geopolymer paste using Romanian material source, various ratios of Na2SiO3 solution/ NaOH solution were produced, keeping the fly ash/alkaline activator ratio constant. All the mixes were then cured at 70 °C for 24 hours and tested at 2 and 7 days, respectively. The aim of this paper is to present the preliminary compressive strength results for producing fly ash based geopolymer paste using Romanian material sources, the effect of alkaline activators ratio on the compressive strength and studying the directions for future research.
Song, Jun Hee; Kim, Hak Kun; Kim, Sam Yeon
2014-07-01
Laminated fiber-reinforced composites can be applied to an insulating structure of a nuclear fusion device. It is necessary to investigate the interlaminar fracture characteristics of the laminated composites for the assurance of design and structural integrity. The three methods used to prepare the glass fiber reinforced plastic composites tested in this study were vacuum pressure impregnation, high pressure laminate (HPL), and prepreg laminate. We discuss the design criteria for safe application of composites and the shear-compressive test methods for evaluating mechanical properties of the material. Shear-compressive tests could be performed successfully using series-type test jigs that were inclined 0°, 30°, 45°, 60°, and 75° to the normal axis. Shear strength depends strongly on the applied compressive stress. The design range of allowable shear stress was extended by use of the appropriate composite fabrication method. HPL had the largest design range, and the allowable interlaminar shear stress was 0.254 times the compressive stress.
Scafè, M.; Raiteri, G.; Brentari, A.; Dlacic, R.; Troiani, E.; Falaschetti, M. P.; Besseghini, E.
2014-01-01
In this work has been estimated the compressive strength of a unidirectional lamina of a carbon/epoxy composite material, using the cross-ply and angle-ply laminates. Over the years various methods have been developed to deduce compressive properties of composite materials reinforced with long fibres. Each of these methods is characterized by a specific way of applying load to the specimen. The method chosen to perform the compression tests is the Wyoming Combined Loading Compr...
Energy Technology Data Exchange (ETDEWEB)
Kannan, S., E-mail: kannan.dgl201127@gmail.com [Department of Mechanical Engineering and Mining Machinery Engineering, Indian Institute of Technology (ISM), Dhanbad, Jharkhand, India, 826004 (India); Senthil Kumaran, S., E-mail: sskumaran@ymail.com [Research and Development Center, Department of Mechanical Engineering, RVS Educational Trust' s Group of Institutions, RVS School of Engineering and Technology, Dindigul, Tamilnadu, India, 624005 (India); Kumaraswamidhas, L.A., E-mail: lakdhas1978@gmail.com [Department of Mechanical Engineering and Mining Machinery Engineering, Indian School of Mines University, Dhanbad, Jharkhand, India, 826004 (India)
2016-05-05
In this present study, Tungsten inert gas (TIG) welding was applied to weld the dissimilar materials and authenticate the mechanical and metallurgical properties of tube to tube plate made up of commercial aluminium and Al 2025 respectively using an Zirconiated tungsten electrode along with filler material aluminium ER 2219. In total, twenty five pieces has been subjected to compression strength and hardness value to evaluate the optimal joint strength. The three optimization technique has been used in this experiment. Taguchi L{sub 25} orthogonal array is used to identify the most influencing process parameter which affects the joint strength. ANOVA method is measured for both compression strength and hardness to calculate the percentage of contribution for each process parameter. Genetic algorithm is used to validate the results obtained from the both experimental value and optimization value. The micro structural study is depicted the welding joints characterization in between tube to tube plate joints. The radiograph test is conducted to prove the welds are non-defective and no flaws are found during the welding process. The mechanical property of compression strength and hardness has been measured to obtain the optimal joint strength of the welded sample was about 174.846 MPa and 131.364 Hv respectively. - Highlights: • Commercial Al tube and Al 2025 tube plate successfully welded by TIG welding. • Compression strength and hardness value proves to obtain optimal joint strength. • The maximum compression and hardness was achieved in various input parameters.
International Nuclear Information System (INIS)
Kannan, S.; Senthil Kumaran, S.; Kumaraswamidhas, L.A.
2016-01-01
In this present study, Tungsten inert gas (TIG) welding was applied to weld the dissimilar materials and authenticate the mechanical and metallurgical properties of tube to tube plate made up of commercial aluminium and Al 2025 respectively using an Zirconiated tungsten electrode along with filler material aluminium ER 2219. In total, twenty five pieces has been subjected to compression strength and hardness value to evaluate the optimal joint strength. The three optimization technique has been used in this experiment. Taguchi L_2_5 orthogonal array is used to identify the most influencing process parameter which affects the joint strength. ANOVA method is measured for both compression strength and hardness to calculate the percentage of contribution for each process parameter. Genetic algorithm is used to validate the results obtained from the both experimental value and optimization value. The micro structural study is depicted the welding joints characterization in between tube to tube plate joints. The radiograph test is conducted to prove the welds are non-defective and no flaws are found during the welding process. The mechanical property of compression strength and hardness has been measured to obtain the optimal joint strength of the welded sample was about 174.846 MPa and 131.364 Hv respectively. - Highlights: • Commercial Al tube and Al 2025 tube plate successfully welded by TIG welding. • Compression strength and hardness value proves to obtain optimal joint strength. • The maximum compression and hardness was achieved in various input parameters.
Liquid jets injected into non-uniform crossflow
Tambe, Samir
An experimental study has been conducted with liquid jets injected transversely into a crossflow to study the effect of non-uniformities in the crossflow velocity distribution to the jet behavior. Two different non-uniform crossflows were created during this work, a shear-laden crossflow and a swirling crossflow. The shear-laden crossflow was generated by merging two independent, co-directional, parallel airstreams creating a shear mixing layer at the interface between them. The crossflow exhibited a quasi-linear velocity gradient across the height of the test chamber. By varying the velocities of the two airstreams, the sense and the slope of the crossflow velocity gradient could be changed. Particle Image Velocimetry (PIV) studies were conducted to characterize the crossflow. The parameter, UR, is defined as the ratio of the velocities of the two streams and governs the velocity gradient. A positive velocity gradient was observed for UR > 1 and a negative velocity gradient for UR Phase Doppler Particle Anemometry (PDPA) studies were conducted to study the penetration and atomization of 0.5 mm diameter water jets injected into this crossflow. The crossflow velocity gradient was observed to have a significant effect on jet penetration as well as the post breakup spray. For high UR (> 1), jet penetration increased and the Sauter Mean Diameter (SMD) distribution became more uniform. For low UR (Doppler Velocimetry (LDV) was used to study the crossflow velocities. The axial (Ux) and the tangential (Utheta) components of the crossflow velocity were observed to decrease with increasing radial distance away from the centerbody. The flow angle of the crossflow was smaller than the vane exit angle, with the difference increasing with the vane exit angle. Water jets were injected from a 0.5 mm diameter orifice located on a cylindrical centerbody. Multi-plane PIV measurements were conducted to study the penetration and droplet velocity distribution of the jets. The jets were
Directory of Open Access Journals (Sweden)
Tilak B. Vidya
2015-06-01
Full Text Available This paper presents the effect of coir fibres on the compaction and unconfined compressive strength of a bentonite-lime-gypsum mixture. The coir fiber content varied from 0.5 to 2 %. The results indicated that the dry unit weight and the optimum moisture content of a bentonite – lime mix increased with the addition of gypsum. The unconfined compressive strength of the bentonite increased with the increase in the lime content up to 8 %. Beyond 8 %, the unconfined compressive strength decreased. The dry unit weight of the reference mix decreased, and the optimum moisture content increased with the addition of coir fibre. The unconfined compressive strength of the bentonite + 8 % lime mix increased up to 4 % with the gypsum. Beyond 4 %, the unconfined compressive strength decreased. The unconfined compressive strength of the reference mix increased with the addition of coir fibre up to a fibre content of 1.5 %. The unconfined compressive strength of the reference mix-coir fibre composite was less in comparison to the reference mix. The unconfined compressive strength of the bentonite increased with the addition of lime and gypsum and with the increase in the curing period. The improvement in the post-peak region was better for the reference mix with reinforced coir fibres as compared to the unreinforced reference mix. The improved post-peak behaviour of the bentonite-lime-gypsum-coir fibre mixture could boost the construction of temporary roads on such problematic soils. Further, its use will also provide an environmental motivation for providing a means of consuming large quantities of coir fibres.
Okasha , Nader M
2017-01-01
International audience; Concrete is recognized as the second most consumed product in our modern life after water. The variability in concrete properties is inevitable. The concrete mix is designed for a compressive strength that is different from, typically higher than, the value specified by the structural designer. Ways to calculate the compressive strength to be used in the mix design are provided in building and structural codes. These ways are all based on criteria related purely and on...
International Nuclear Information System (INIS)
Shaikh, F.U.A.; Supit, S.W.M.; Sarker, P.K.
2014-01-01
Highlights: • The addition of NS compensates low early age compressive strength of HVFA system. • NS also contributes to later age compressive strength gain of HVFA system. • The XRD results confirm the reduction of CH in HVFA paste due to addition of NS. - Abstract: This paper presents the effect of nano silica (NS) on the compressive strength of mortars and concretes containing different high volume fly ash (HVFA) contents ranging from 40% to 70% (by weight) as partial replacement of cement. The compressive strength of mortars is measured at 7 and 28 days and that for concretes is measured at 3, 7, 28, 56 and 90 days. The effects of NS in microstructure development and pozzolanic reaction of pastes containing above HVFA contents are also studied through backscattered electron (BSE) image and X-ray diffraction (XRD) analysis. Results show that among different NS contents ranging from 1% to 6%, cement mortar containing 2% NS exhibited highest 7 and 28 days compressive strength. This NS content (2%) is then added to the HVFA mortars and concretes and the results show that the addition of 2% NS improved the early age (7 days) compressive strength of mortars containing 40% and 50% fly ash by 5% and 7%, respectively. However, this improvement is not observed at high fly ash contents beyond 50%. On the other hand, all HVFA mortars exhibited improvement in 28 days compressive strength due to addition of 2% NS and the most significant improvement is noticed in mortars containing more than 50% fly ash. In HVFA concretes, the improvement of early age (3 days) compressive strength is also noticed due to addition of 2% NS. The BSE and XRD analysis results also support the above findings
Directory of Open Access Journals (Sweden)
Humaira Kanwal
2018-04-01
Full Text Available Effective utilization of the available resources is imperative approach to achieve the apex of productivity. The modern world is focusing on the conditioning, sustainability and recycling of the assets by imparting innovative techniques and methodologies. Keeping this in view, an experimental study was conducted to evaluate the strength of concrete made with treated waste water for structural use. In this study ninetysix cylinders of four mixes with coarse aggregates in combination with FW (Fresh Water, WW (Wastewater, TWW (Treated Wastewater and TS (Treated Sewagewere prepared. The workability of fresh concrete was checked before pouring of cylinders. The test cylinders were left for 7, 14, 21 and 28 days for curing. After curing, the compressive strength was measured on hardened concrete cylinders accordingly. Test results showed that workability of all the four mixes were between 25-50mm but ultimate compressive strength of concrete with WW was decreased and with TWW, TS at the age of 28 days do not change significantly. This research will open a new wicket in the horizon of recycling of construction materials. The conditioning and cyclic utilization will reduce the cost of the construction and building materials as well as minimize the use of natural resources. This novelty and calculating approach will save our natural assets and resources.
Directory of Open Access Journals (Sweden)
Guangsheng Liu
2017-01-01
Full Text Available Backfill is commonly used in underground mines. The quality control of the backfill is a key step to ensure it meets the designed strength requirement. This is done through sample collection from the underground environment, followed by uniaxial compression tests to obtain the Uniaxial Compressive Strength (UCS in the laboratory. When the cylindrical cemented backfill samples are axially loaded to failure, several failure modes can be observed and mainly classified into diagonal shear failure and axial split failure. To date, the UCS obtained by these two failure modes are considered to be the same with no distinction between them. In this paper, an analysis of the UCS results obtained on a cemented hydraulic backfill made of alluvial sand at a Canadian underground mine over the course of more than three years is presented. The results show that the UCS values obtained by diagonal shear failure are generally higher than those obtained by axial split failure for samples with the same recipe and curing time. This highlights the importance of making a distinction between the UCS values obtained by the two different modes of failure. Their difference in failure mechanism is explained. Further investigations on the sources of the data dispersion tend to indicate that the UCS obtained by laboratory tests following the current practice may not be representative of the in-situ strength distribution in the underground stopes due to segregation in cemented hydraulic backfill.
Compressive Strength of Steel Frames after Welding with Micro-Jet Cooling
Directory of Open Access Journals (Sweden)
Hadryś D.
2016-03-01
Full Text Available Low carbon steel weld structures generally exhibit a very linear stress-strain relationship. In the study of strength of materials, the compressive strength is the capacity of a material or structure to withstand loads tending to reduce size of structure. It is mainly measured by plotting applied force against deformation in a testing machine. Compressive strength is a main key value for design of welded structures.The main goal of that paper was analysing of plastic properties of frame welds which were made with various parameters of micro-jet cooling. New technology of micro-jet welding could be regarded as a new way to improve plastic properties of welds. It allows to obtain welds with better mechanical properties in comparison to ordinary welding method. Furthermore it is possible to steering of weld structure and properties of the weld. There were given main information about influence of various micro-jet gases on metallographic and properties of structure steel welds.
Ibrahim, M. H. Wan; Mangi, Sajjad Ali; Burhanudin, M. K.; Ridzuan, M. B.; Jamaluddin, N.; Shahidan, S.; Wong, YH; Faisal, SK; Fadzil, M. A.; Ramadhansyah, P. J.; Ayop, S. S.; Othman, N. H.
2017-11-01
This paper presents the effects of using palm oil biomass (POB) clinker with polypropylene (PP) fibres in concrete on its compressive and flexural strength performances. Due to infrastructural development works, the use of concrete in the construction industry has been increased. Simultaneously, it raises the demand natural sand, which causes depletion of natural resources. While considering the environmental and economic benefits, the utilization of industrial waste by-products in concrete will be the alternative solution of the problem. Among the waste products, one of such waste by-product is the palm oil biomass clinker, which is a waste product from burning processes of palm oil fibres. Therefore, it is important to utilize palm oil biomass clinker as partial replacement of fine aggregates in concrete. Considering the facts, an experimental study was conducted to find out the potential usage of palm oil fibres in concrete. In this study, total 48 number of specimens were cast to evaluate the compressive and flexural strength performances. Polypropylene fibre was added in concrete at the rate of 0.2%, 0.4% and 0.6%, and sand was replaced at a constant rate of 10% with palm oil biomass clinker. The flexural strength of concrete was noticed in the range of 2.25 MPa and 2.29 MPa, whereas, the higher value of flexural strength was recorded with 0.4% polypropylene fibre addition. Hence, these results show that the strength performances of concrete containing POB clinker could be improved with the addition of polypropylene fibre.
Perceka, Wisena; Liao, Wen-Cheng; Wang, Yo-de
2016-01-01
Addition of steel fibers to high strength concrete (HSC) improves its post-peak behavior and energy absorbing capability, which can be described well in term of toughness. This paper attempts to obtain both analytically and experimentally the efficiency of steel fibers in HSC columns with hybrid confinement of transverse reinforcement and steel fibers. Toughness ratio (TR) to quantify the confinement efficiency of HSC columns with hybrid confinement is proposed through a regression analysis by involving sixty-nine TRs of HSC without steel fibers and twenty-seven TRs of HSC with hybrid of transverse reinforcement and steel fibers. The proposed TR equation was further verified by compression tests of seventeen HSC columns conducted in this study, where twelve specimens were reinforced by high strength rebars in longitudinal and transverse directions. The results show that the efficiency of steel fibers in concrete depends on transverse reinforcement spacing, where the steel fibers are more effective if the spacing transverse reinforcement becomes larger in the range of 0.25–1 effective depth of the section column. Furthermore, the axial load–strain curves were developed by employing finite element software (OpenSees) for simulating the response of the structural system. Comparisons between numerical and experimental axial load–strain curves were carried out. PMID:28773391
Aggregate effects on γ-ray shielding characteristics and compressive strength on concrete
International Nuclear Information System (INIS)
Oh, Jeong Hwan; Choi, Soo Seok; Mun, Young Bun; Lee, Jae Hyung; Choi, Hyun Kook
2016-01-01
We observed the γ-ray shielding characteristics and compressive strength of five types of concrete using general aggregates and high-weight aggregates. The aggregates were classified into fine aggregate and coarse aggregate according to the average size. The experimental results obtained an attenuation coefficient of 0.371 cm-1 from a concrete with the oxidizing slag sand (OSS) and oxidizing slag gravel (OSG) for a γ-ray of "1"3"7Cs, which is improved by 2% compared with a concrete with typical aggregates of sand and gravel. In the unit weight measurement, a concrete prepared by iron ore sand (IOS) and OSG had the highest value of 3,175 kg·m"-"3. Although the unit weight of the concrete with OSS and OSG was 3,052 kg·m"-"3, which was lower than the maximum unit weight condition by 123 kg·m"-"3, its attenuation coefficient was improved by 0.012 cm-1. The results of chemical analysis of aggregates revealed that the magnesium content in oxidizing slag was lower than that in iron ore, while the calcium content was higher. The concrete with oxidizing slag aggregates demonstrated enhanced γ-ray shielding performance due to a relatively high calcium content compared with the concrete with OSS and OSG in spite of a low unit weight. All sample concretes mixed with high-weight aggregates had higher compressive strength than the concrete with typical sand and gravel. When OSS and IOS were used, the highest compressive strength was 50.2 MPa, which was an improvement by 45% over general concrete, which was achieved after four weeks of curing
Aggregate effects on γ-ray shielding characteristics and compressive strength on concrete
Energy Technology Data Exchange (ETDEWEB)
Oh, Jeong Hwan; Choi, Soo Seok [Jeju National University, Jeju (Korea, Republic of); Mun, Young Bun; Lee, Jae Hyung; Choi, Hyun Kook [Sungshin Cement Co., Ltd, Sejong (Korea, Republic of)
2016-12-15
We observed the γ-ray shielding characteristics and compressive strength of five types of concrete using general aggregates and high-weight aggregates. The aggregates were classified into fine aggregate and coarse aggregate according to the average size. The experimental results obtained an attenuation coefficient of 0.371 cm-1 from a concrete with the oxidizing slag sand (OSS) and oxidizing slag gravel (OSG) for a γ-ray of {sup 137}Cs, which is improved by 2% compared with a concrete with typical aggregates of sand and gravel. In the unit weight measurement, a concrete prepared by iron ore sand (IOS) and OSG had the highest value of 3,175 kg·m{sup -3}. Although the unit weight of the concrete with OSS and OSG was 3,052 kg·m{sup -3}, which was lower than the maximum unit weight condition by 123 kg·m{sup -3}, its attenuation coefficient was improved by 0.012 cm-1. The results of chemical analysis of aggregates revealed that the magnesium content in oxidizing slag was lower than that in iron ore, while the calcium content was higher. The concrete with oxidizing slag aggregates demonstrated enhanced γ-ray shielding performance due to a relatively high calcium content compared with the concrete with OSS and OSG in spite of a low unit weight. All sample concretes mixed with high-weight aggregates had higher compressive strength than the concrete with typical sand and gravel. When OSS and IOS were used, the highest compressive strength was 50.2 MPa, which was an improvement by 45% over general concrete, which was achieved after four weeks of curing.
A non-uniform expansion mechanical safety model of the stent.
Yang, J; Huang, N; Du, Q
2009-01-01
Stents have a serial unstable structure that readily leads to non-uniform expansion. Non-uniform expansion in turn creates a stent safety problem. We explain how a stent may be simplified to a serial unstable structure, and present a method to calculate the non-uniform expansion of the stent on the basis of the serial unstable structure. We propose a safety criterion based on the expansion displacement instead of the strain, and explain that the parameter Rd, the ratio of the maximum displacement of the elements to normal displacement, is meaningful to assess the safety level of the stent. We also examine how laser cutting influences non-uniform expansion. The examples illustrate how to calculate the parameter Rd to assess non-uniform expansion of the stent, and demonstrate how the laser cutting offset and strengthening coefficient of the material influence the stent expansion behaviour. The methods are valuable for assessing stent safety due to non-uniform expansion.
Effect of hydrated lime on compressive strength mortar of fly ash laterite soil geopolymer mortar
Wangsa, F. A.; Tjaronge, M. W.; Djamaluddin, A. R.; Muhiddin, A. B.
2017-11-01
This paper explored the suitability of fly ash, hydrated lime, and laterite soil with several activator (sodium hydroxide and sodium tiosulfate) to produce geopolymer mortar. Furthermore, the heat that released by hydrated lime was used instead of oven curing. In order to produce geopolymer mortar without oven curing, three variations of curing condition has been applied. Based on the result, all the curing condition showed that the hardener mortar can be produced and exhibited the increasing of compressive strength of geopolymer mortar from 3 days to 7 days without oven curing.
DEFF Research Database (Denmark)
Misirlis, K.; Downes, J.; Dow, R.S.
2009-01-01
with initial geometric imperfections. This paper presents the validation of finite element models against a series of plate tests that were performed within this framework and parametric studies that were carried out to identify the effects of geometric imperfections on the ultimate compressive strength......A series of studies has been performed within the MARSTRUCT Network of Excellence on Marine Structures in order to investigate the buckling response of glass fibre reinforced polymer plates. These studies include the fabrication, testing and finite element analysis of a large number of plates...
Czech Academy of Sciences Publication Activity Database
Mishra, A. Deepak; Srigyan, M.; Basu, A.; Rokade, P. J.
2015-01-01
Roč. 80, December 2015 (2015), s. 418-424 ISSN 1365-1609 Institutional support: RVO:68145535 Keywords : uniaxial compressive strength * rock indices * fuzzy inference system * artificial neural network * adaptive neuro-fuzzy inference system Subject RIV: DH - Mining, incl. Coal Mining Impact factor: 2.010, year: 2015 http://ac.els-cdn.com/S1365160915300708/1-s2.0-S1365160915300708-main.pdf?_tid=318a7cec-8929-11e5-a3b8-00000aacb35f&acdnat=1447324752_2a9d947b573773f88da353a16f850eac
Experimental Study on Unconfined Compressive Strength of Basalt Fiber Reinforced Clay Soil
Gao, Lei; Hu, Guohui; Xu, Nan; Fu, Junyi; Xiang, Chao; Yang, Chen
2015-01-01
In order to study the mechanism and effect of basalt fiber reinforced clay soil, a series of unconfined compressive strength tests conducted on clay soil reinforced with basalt fiber have been performed under the condition of optimum water content and maximum dry density. Both the content and length of basalt fiber are considered in this paper. When the effect of content is studied, the 12 mm long fibers are dispersed into clay soil at different contents of 0.05%, 0.1%, 0.15%, 0.20%, 0.25%, 0...
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Ahmadian Khoshemehr Leila
2009-09-01
Full Text Available Background: Luting agents are used to attach indirect restoration into or on the tooth. Poor mechanical properties of cement may be a cause of fracture of this layer and lead to caries and restoration removal. The purpose of this study was to compare the elastic modulus and compressive strength of Ariadent (A Poly and Harvard polycarboxylate (H Poly cements and Vitremer resin modified glass ionomer (RGl.Materials & Methods: In this experimental study 15 specimens were prepared form each experimental cement in Laboratory of Tehran Oil Refining Company. The cylindrical specimens were compressed in Instron machine after 24 hours. Elastic modulus and compressive strength were calculated from stress/strain curve of each specimen. One way ANOVA and Tukey tests were used for statistical analysis and P values<0.05 were considered to be statistically significant.Results: The mean elastic modulus and mean compressive strength were 2.2 GPa and 87.8MPa in H poly, 2.4 GPa and 56.5 MPa in A Poly, and 0.8GPa and 105.6 MPa in RGI, respectively. Statistical analysis showed that compressive strength and elastic modulus of both polycarboxylate cements were significantly different from hybrid ionomer (P<0.05, but the difference between elastic modulus of two types of polycarboxilate cements was not statistically significant. Compressive strength of two polycarboxilate cements were significantly different (P<0.05. Conclusion: An ideal lutting agent must have the best mechanical properties. Between the tested luttins RGl cement had the lowest elastic modulus and the highest compressive strength, but the A poly cement had the highest elastic modulus and the lowest compressive strength. Therefore none of them was the best.
International Nuclear Information System (INIS)
Bai, J.; Chaipanich, A.; Kinuthia, J.M.; O'Farrell, M.; Sabir, B.B.; Wild, S.; Lewis, M.H.
2003-01-01
Compressive strength and hydration characteristics of wastepaper sludge ash-ground granulated blastfurnace slag (WSA-GGBS) blended pastes were investigated at a water to binder (w/b) ratio of 0.5. The strength results are compared to those of normal Portland cement (PC) paste and relative strengths are reported. Early relative strengths (1 day) of WSA-GGBS pastes were very low but a marked gain in relative strength occurred between 1 and 7 days and this increased further after 28 and 90 days. For the 50% WSA-50% GGBS blended paste, the strength achieved at 90 days was nearly 50% of that of the PC control paste. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermogravimetric (TG) analysis were carried out to identify the mineral components in the WSA and the hydration products of WSA and WSA-GGBS pastes. The principal crystalline components in the WSA are gehlenite, calcium oxide, bredigite and α'-C 2 S (stabilised with Al and Mg) together with small amounts of anorthite and calcium carbonate and traces of calcium hydroxide and quartz. The α'-C 2 S and bredigite, which phase separate from liquid phase that forms a glass on cooling, are difficult to distinguish by XRD. The hydration products identified in WSA paste are CH, C 4 AH 13 , C 3 A.0.5CC-bar.0.5CH.H 11.5 and C-S-H gel plus possible evidence of small amounts of C 2 ASH 8 and C 3 A.3CS-bar.H 32 . Based upon the findings, a hydration mechanism is presented, and a model is proposed to explain the observed strength development
International Nuclear Information System (INIS)
Yu Geping; Chang Mingyu; Wang Yeajeng; Chu, David S.L.; Ju Yihzen
1992-01-01
This paper summarizes the nondestructive test to determine the uni-axial compressive strength and free water content of solidified low level radioactive waste. The uni-axial compressive strength is determined by ultrasonic wave propagation speed, and the results are compared with those of compressive tests. Three methods of detecting the surface free water by ultrasonic testing are established, the ultrasonic wave speed, wave form and pulse height are used to determine the existence and amount of the surface free liquid. Possible difficulties are discussed. (author)
Illumination non-uniformity of spirally wobbling beam in heavy ion fusion
International Nuclear Information System (INIS)
Suzuki, T.; Noguchi, K.; Kurosaki, T.; Barada, D.; Kawata, S.; Ma, Y. Y.; Ogoyski, A.I.
2016-01-01
In inertial confinement fusion, the driver beam illumination non-uniformity leads a degradation of fusion energy output. The illumination non-uniformity allowed is less than a few percent in inertial fusion target implosion. Heavy ion beam (HIB) accelerator provides a capability to oscillate a beam axis with a high frequency. The wobbling beams may provide a new method to reduce or smooth the beam illumination non-uniformity. In this paper the HIBs wobbling illumination scheme was optimized. (paper)
Ultimate uniaxial compressive strength of stiffened panel with opening under lateral pressure
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Chang-Li Yu
2015-03-01
Full Text Available This paper concentrated on the ultimate uniaxial compressive strength of stiffened panel with opening under lateral load and also studied the design-oriented formulae. For this purpose, three series of well executed experiments on longitudinal stiffened panel with rectangular opening subjected to the combined load have been selected as test models. The finite element analysis package, ABAQUS, is used for simulation with considering the large elasticplastic deflection behavior of stiffened panels. The feasibility of the numerical procedure is verified by a good agreement of experimental results and numerical results. More cases studies are executed employing nonlinear finite element method to analyze the influence of design variables on the ultimate strength of stiffened panel with opening under combined pressure. Based on data, two design formulae corresponding to different opening types are fitted, and accuracy of them is illustrated to demonstrate that they could be applied to basic design of practical engineering structure.
Energy Technology Data Exchange (ETDEWEB)
Yi, Wei [School of Mechanical and Chemical Engineering, The University of Western Australia, Perth, WA 6009 (Australia); School of Dentistry, The University of Western Australia, WA 6009 (Australia); Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110004 (China); Hu, Xiaozhi, E-mail: xiao.zhi.hu@uwa.edu.au [School of Mechanical and Chemical Engineering, The University of Western Australia, Perth, WA 6009 (Australia); Ichim, Paul [School of Dentistry, The University of Western Australia, WA 6009 (Australia); Sun, Xudong [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110004 (China)
2012-12-15
Brittle low-strength and low-toughness pressable dental ceramic can be reinforced by ductile elongated gold-particles (GP). A customized crown structure can be adequately strengthened by distributing GP only in critical sections of the crown, where high tensile stresses are experienced. In the present study, a non-uniformly structured ceramic-matrix composite with excellent interfacial bonding, twofold fracture toughness and strength at desired locations, is fabricated using pressable dental ceramic and GP. The layout pattern and sequence of different GP/ceramic powder mixtures, high-temperature flow properties of these mixtures during hot-pressing and the sample mold geometry are used to control the distribution and locations of GP for selective toughening and strengthening. Nano-crystalline structures of the pressable ceramic-matrix and the nano-scaled interfacial region around GP have been revealed by high-magnification field-emission scanning electron microscopy. Toughening and strengthening mechanisms of the elongated GP including residual stresses from composite processing and ductile fracture of GP are discussed together with SEM observations. Bulk flexural strength and local micro-indentation fracture and deformation characteristics of the selective-toughened ceramic/metal composite have been compared to those of the monolithic pressable ceramic to validate the toughening and strengthening mechanisms.
International Nuclear Information System (INIS)
Yi, Wei; Hu, Xiaozhi; Ichim, Paul; Sun, Xudong
2012-01-01
Brittle low-strength and low-toughness pressable dental ceramic can be reinforced by ductile elongated gold-particles (GP). A customized crown structure can be adequately strengthened by distributing GP only in critical sections of the crown, where high tensile stresses are experienced. In the present study, a non-uniformly structured ceramic–matrix composite with excellent interfacial bonding, twofold fracture toughness and strength at desired locations, is fabricated using pressable dental ceramic and GP. The layout pattern and sequence of different GP/ceramic powder mixtures, high-temperature flow properties of these mixtures during hot-pressing and the sample mold geometry are used to control the distribution and locations of GP for selective toughening and strengthening. Nano-crystalline structures of the pressable ceramic–matrix and the nano-scaled interfacial region around GP have been revealed by high-magnification field-emission scanning electron microscopy. Toughening and strengthening mechanisms of the elongated GP including residual stresses from composite processing and ductile fracture of GP are discussed together with SEM observations. Bulk flexural strength and local micro-indentation fracture and deformation characteristics of the selective-toughened ceramic/metal composite have been compared to those of the monolithic pressable ceramic to validate the toughening and strengthening mechanisms.
Compressive Strength of EN AC-44200 Based Composite Materials Strengthened with α-Al2O3 Particles
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Kurzawa A.
2017-06-01
Full Text Available The paper presents results of compressive strength investigations of EN AC-44200 based aluminum alloy composite materials reinforced with aluminum oxide particles at ambient and at temperatures of 100, 200 and 250°C. They were manufactured by squeeze casting of the porous preforms made of α-Al2O3 particles with liquid aluminum alloy EN AC-44200. The composite materials were reinforced with preforms characterized by the porosities of 90, 80, 70 and 60 vol. %, thus the alumina content in the composite materials was 10, 20, 30 and 40 vol.%. The results of the compressive strength of manufactured materials were presented and basing on the microscopic observations the effect of the volume content of strengthening alumina particles on the cracking mechanisms during compression at indicated temperatures were shown and discussed. The highest compressive strength of 470 MPa at ambient temperature showed composite materials strengthened with 40 vol.% of α-Al2O3 particles.
Yokozeki, Tomohiro; Aoki, Yuichiro; Ogasawara, Toshio
It has been recognized that damage resistance and strength properties of CFRP laminates can be improved by using thin-ply prepregs. This study investigates the damage behaviors and compressive strength of CFRP laminates using thin-ply and standard prepregs subjected to out-of-plane impact loadings. CFRP laminates used for the evaluation are prepared using the standard prepregs, thin-ply prepregs, and combinations of the both. Weight-drop impact test and post-impact compression test of quasi-isotropic laminates are performed. It is shown that the damage behaviors are different between the thin-ply and the standard laminates, and the compression-after-impact strength is improved by using thin-ply prepregs. Effects of the use of thin-ply prepregs and the layout of thin-ply layers on the damage behaviors and compression-after-impact properties are discussed based on the experimental results.
Tsoy, PA
2018-03-01
In order to determine the empirical relationship between the linear dimensions of step-shaped macrocracks in geomaterials as well as deformation and strength characteristics of geomaterials (ultimate strength, modulus of deformation) under uniaxial compression, the artificial flat alabaster specimens with the through discontinuities have been manufactured and subjected to a series of the related physical tests.
The effects of aging on compressive strength of low-level radioactive waste form samples
International Nuclear Information System (INIS)
McConnell, J.W. Jr.; Neilson, R.M. Jr.
1996-06-01
The Field Lysimeter Investigations: Low-Level Waste Data Base Development Program, funded by the US Nuclear Regulatory Commission (NRC), is (a) studying the degradation effects in organic ion-exchange resins caused by radiation, (b) examining the adequacy of test procedures recommended in the Branch Technical Position on Waste Form to meet the requirements of 10 CFR 61 using solidified ion-exchange resins, (c) obtaining performance information on solidified ion-exchange resins in a disposal environment, and (d) determining the condition of liners used to dispose ion-exchange resins. Compressive tests were performed periodically over a 12-year period as part of the Technical Position testing. Results of that compressive testing are presented and discussed. During the study, both portland type I-II cement and Dow vinyl ester-styrene waste form samples were tested. This testing was designed to examine the effects of aging caused by self-irradiation on the compressive strength of the waste forms. Also presented is a brief summary of the results of waste form characterization, which has been conducted in 1986, using tests recommended in the Technical Position on Waste Form. The aging test results are compared to the results of those earlier tests. 14 refs., 52 figs., 5 tabs
International Nuclear Information System (INIS)
Noor Azreen Masenwat; Mohamad Pauzi Ismail; Suhairy Sani; Ismail Mustapha; Nasharuddin Isa; Mohamad Haniza Mahmud; Mohammad Shahrizan Samsu
2014-01-01
To prevent radiation leaks at nuclear reactors, high-density concrete is used as an absorbent material for radiation from spreading into the environment. High-density concrete is a mixture of cement, sand, aggregate (usually high-density minerals) and water. In this research, hematite stone is used because of its mineral density higher than the granite used in conventional concrete mixing. Mix concrete in this study were divided into part 1 and part 2. In part 1, the concrete mixture is designed with the same ratio of 1: 2: 4 but differentiated in terms of water-cement ratio (0.60, 0.65, 0.70, 0.75, 0.80 ). Whereas, in part 2, the concrete mixture is designed to vary the ratio of 1: 1: 2, 1: 1.5: 3, 1: 2: 3, 1: 3: 6, 1: 2: 6 with water-cement ratio (0.7, 0.8, 0.85, 0.9). In each section, the division has also performed in a mixture of sand and fine sand hematite. Then, the physical characteristics of the density and the compressive strength of the mixture of part 1 and part 2 is measured. Comparisons were also made in terms of absorption of radiation by Cs-137 and Co-60 source for each mix. This paper describes and discusses the relationship between the concrete mixture ratio, the relationship with the water-cement ratio, compressive strength, density, different mixture of sand and fine sand hematite. (author)
In vitro comparison of DE-QCT parameters with the compressive strength of cancellous bone
International Nuclear Information System (INIS)
Oravez, W.T.; Robertson, D.D.
1986-01-01
Quantitative computed tomography (QCT) is used as a method for assessing bone mineral in patients with osteoporosis. The implication being that if the mass of bone mineral is low enough then the patient is at risk for developing symptoms, i.e., fracture. The authors performed an in vitro test which compared dual-energy-QCT (DE-QCT) parameters with compressive strength. The bone samples were placed in a water bath and CT scanned using a Siemens DR-3. Alternating x-ray pulses of 125 and 85 kVp were used to generate the dual energy images. Four images, high kVp, low kVp, monoenergenic, and calcium equivalent, were reconstructed from each scan. A specially constructed bone mineral calibration phantom, consisting of a polyethylene rod and varying tubes of K2HP04, was placed within the water bath along with the specimens. Comparisons will be made between the various DE parameters and their relationship to the compressive strength of cancellous bone. The critical effect of trabecular bone orientation will also be discussed
Development of ultra-lightweight slurries with high compressive strength for use in oil wells
Energy Technology Data Exchange (ETDEWEB)
Suzart, J. Walter P. [Halliburton Company, Houston, TX (United States); Farias, A.C. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil); Ribeiro, Danilo; Fernandes, Thiago; Santos, Reened [Halliburton Energy Services Aberdeen, Scotland (United Kingdom)
2008-07-01
Formations with low fracture gradients or depleted reservoirs often lead to difficult oil well cementing operations. Commonly employed cement slurries (14.0 to 15.8 lb/gal), generate an equivalent circulating density (ECD) higher than the fracture gradient and ultimately lead to formation damage, lost circulation and a decreased top of cement. Given the high price of oil, companies are investing in those and other wells that are difficult to explore. Naturally, lightweight cement slurries are used to reduce the ECD (10.0 to 14.0 lb/gal), using additives to trap water and stabilize the slurry. However, when the density reaches 11.0 lb/gal, the increase in water content may cause a change in characteristics. The focus of this study is extreme cases where it is necessary to employ ultra-lightweight cement slurries (5.5 to 10.0 lb/gal). Foamed slurries have been widely used, and the objective is to set an alternative by developing cement slurries containing uncompressible microspheres, aiming for a density of 7.5 lb/gal as well as high compressive strength. Another benefit in contrast to preparing foamed cement slurries is that there is no requirement for special equipment in the field. Routine laboratory tests such as fluid-loss control, sedimentation, thickening time, free water, compressive strength, and rheology (at room and high temperatures) were performed. Thus, it was concluded that the proposed cement slurries can be used in oil wells. (author)
Influence of the waste glass in the axial compressive strength of Portland cement concrete
International Nuclear Information System (INIS)
Miranda Junior, E.J.P.; Paiva, A.E.M.
2012-01-01
In this work, was studied the influence of the incorporation of waste glass, coming from the stage of thinning and polishing of a company of thermal glass treatments, in the axial compressive strength of Portland cement concrete. The coarse and ground aggregates used was crushed stone and sand, respectively. For production of the concrete, percentages of glass residues of 5%, 10% and 20% had been used in substitution to the sand, and relations water/cement (a/c) 0,50, 0,55 and 0,58. The cure of the test bodies was carried through in 7, 14 and 28 days. The statistics analysis of the results was carried out through of the analysis of variance for each one of the cure times. From the results of the compressive strength of the concrete, it could be observed that the concrete has structural application for the relation a/c 0,5, independently of waste glass percentage used, and for the relation a/c 0,55 with 20% of waste glass. (author)
Compressive strength and microstructural characteristics of class C fly ash geopolymer
Energy Technology Data Exchange (ETDEWEB)
Guo, Xiaolu; Shi, Huisheng; Dick, Warren A [Key Laboratory of Advanced Civil Engineering Materials (Tongji University), Shanghai (China)
2010-02-15
Geopolymers prepared from a class C fly ash (CFA) and a mixed alkali activator of sodium hydroxide and sodium silicate solution were investigated. A high compressive strength was obtained when the modulus of the activator viz., molar ratio of SiO{sub 2}/Na{sub 2}O was 1.5, and the proper content of this activator as evaluated by the mass proportion of Na{sub 2}O to CFA was 10%. The compressive strength of these samples was 63.4 MPa when they were cured at 75{sup o}C for 8 h followed by curing at 23{sup o}C for 28 d. In FTIR spectroscopy, the main peaks at 1036 and 1400 cm{sup -1} have been attributed to asymmetric stretching of Al-O/Si-O bonds, while those at 747 cm{sup -1} are due to the Si-O-Si/Si-O-Al bending band. The main geopolymeric gel and calcium silicate hydrate (C-S-H) gel co-exist and bond some remaining unreacted CFA spheres as observed in XRD and SEM-EXDA. The presence of gismondine (zeolite) was also observed in the XRD pattern.
Effect of isothermal annealing on the compressive strength of a ZrAlNiCuNb metallic glass
International Nuclear Information System (INIS)
Song Min; He Yuehui
2011-01-01
Research highlights: → Only structural relaxation happens during annealing at the temperature below T g . → Nanocrystallization happens during annealing at the temperature above T g . → The compressive strength increases with annealing time up to 20 min. → The compressive strength decreases with annealing time after 20 min. - Abstract: The effects of isothermal annealing on the microstructures and compressive strength of a Zr 56 Al 10.9 Ni 4.6 Cu 27.8 Nb 0.7 bulk metallic glass (BMG) have been studied using X-ray diffraction, scanning electron microscopy and compression tests. It has been shown that only structural relaxation happens during annealing at the temperature below T g (glass transition temperature), while both structural relaxation and nanocrystallization happen during annealing at the temperature above T g . Compression tests indicated that the strength of the BMG increases with annealing time at 437 deg. C up to 20 min, after which the strength starts to decrease. The strength evolution of the BMG with the annealing time is due to combined effects of the variations of the free volume and nanocrystals.
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Babafemi A.J.
2012-01-01
Full Text Available This study investigates the influence of curing age and mix proportions on the compressive strength of volcanic ash (VA blended cement laterized concrete. A total of 288 cubes of 100mm dimensions were cast and cured in water for 3, 7, 28, 56, 90 and 120 days of hydration with cement replacement by VA and sand replacement by laterite both ranging from 0 to 30% respectively while a control mix of 28-day target strength of 25N/mm2 (using British Method was adopted. The results show that the compressive strength of the VA-blended cement laterized concrete increased with the increase in curing age but decreased as the VA and laterite (LAT contents increased. The optimum replacement level was 20%LAT/20%VA. At this level the compressive strength increased with curing age at a decreasing rate beyond 28 days. The target compressive strength of 25N/mm2 was achieved for this mixture at 90 days of curing. VA content and curing age was noted to have significant effect (α ≤ 0.5 on the compressive strength of the VA-blended cement laterized concrete.
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Nan Ji Jin
2017-01-01
Full Text Available The compressive strength of vinyl ester polymer concrete is predicted using the maturity method. The compressive strength rapidly increased until the curing age of 24 hrs and thereafter slowly increased until the curing age of 72 hrs. As the MMA content increased, the compressive strength decreased. Furthermore, as the curing temperature decreased, compressive strength decreased. For vinyl ester polymer concrete, datum temperature, ranging from −22.5 to −24.6°C, decreased as the MMA content increased. The maturity index equation for cement concrete cannot be applied to polymer concrete and the maturity of vinyl ester polymer concrete can only be estimated through control of the time interval Δt. Thus, this study introduced a suitable scaled-down factor (n for the determination of polymer concrete’s maturity, and a factor of 0.3 was the most suitable. Also, the DR-HILL compressive strength prediction model was determined as applicable to vinyl ester polymer concrete among the dose-response models. For the parameters of the prediction model, applying the parameters by combining all data obtained from the three different amounts of MMA content was deemed acceptable. The study results could be useful for the quality control of vinyl ester polymer concrete and nondestructive prediction of early age strength.
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Sherif El-Gamal
2015-01-01
Full Text Available Due to their high strength, corrosion resistance, and durability, fiber reinforced polymers (FRP are very attractive for civil engineering applications. One of these applications is the strengthening of concrete columns with FRP sheets. The performance of this strengthening technique at elevated temperature is still questionable and needs more investigations. This research investigates the effects of exposure to high temperatures on the compressive strength of concrete cylinders wrapped with glass and carbon FRP sheets. Test specimens consisted of 30 unwrapped and 60 wrapped concrete cylinders. All specimens were exposed to temperatures of 100, 200, and 300°C for periods of 1, 2, and 3 hours. The compressive strengths of the unwrapped concrete cylinders were compared with their counterparts of the wrapped cylinders. For the unwrapped cylinders, test results showed that the elevated temperatures considered in this study had almost no effect on their compressive strength; however, the wrapped specimens were significantly affected, especially those wrapped with GFRP sheets. The compressive strength of the wrapped specimens decreased as the exposure period and the temperature level increased. After three hours of exposure to 300°C, a maximum compressive strength loss of about 25.3% and 37.9%, respectively, was recorded in the wrapped CFRP and GFRP specimens.
International Nuclear Information System (INIS)
Tallent, O.K.; McDaniel, E.W.; Godsey, T.T.
1986-04-01
Compressive strength data for grouts prepared from three different nuclear waste materials have been correlated. The wastes include ORNL low-level waste (LLW) solution, Hanford Facility Waste (HFW) solution, and Hanford cladding removal waste (CRW) slurry. Data for the three wastes can be represented with a 0.96 coefficient of correlation by the following equation: S = -9.56 + 9.27 D/I + 18.11/C + 0.010 R, where S denotess 28-d compressive strength, in mPa; D designates Waste concentration, fraction of the original; I is ionic strength; C denotes Attapulgite-150 clay content of dry blend, in wt %; and R is the mix ratio, kg/m 3 . The equation may be used to estimate 28-d compressive strengths of grouts prepared within the compositional range of this investigation
Jin, Minglei; Jin, Weiqi; Li, Yiyang; Li, Shuo
2015-08-01
In this paper, we propose a novel scene-based non-uniformity correction algorithm for infrared image processing-temporal high-pass non-uniformity correction algorithm based on grayscale mapping (THP and GM). The main sources of non-uniformity are: (1) detector fabrication inaccuracies; (2) non-linearity and variations in the read-out electronics and (3) optical path effects. The non-uniformity will be reduced by non-uniformity correction (NUC) algorithms. The NUC algorithms are often divided into calibration-based non-uniformity correction (CBNUC) algorithms and scene-based non-uniformity correction (SBNUC) algorithms. As non-uniformity drifts temporally, CBNUC algorithms must be repeated by inserting a uniform radiation source which SBNUC algorithms do not need into the view, so the SBNUC algorithm becomes an essential part of infrared imaging system. The SBNUC algorithms' poor robustness often leads two defects: artifacts and over-correction, meanwhile due to complicated calculation process and large storage consumption, hardware implementation of the SBNUC algorithms is difficult, especially in Field Programmable Gate Array (FPGA) platform. The THP and GM algorithm proposed in this paper can eliminate the non-uniformity without causing defects. The hardware implementation of the algorithm only based on FPGA has two advantages: (1) low resources consumption, and (2) small hardware delay: less than 20 lines, it can be transplanted to a variety of infrared detectors equipped with FPGA image processing module, it can reduce the stripe non-uniformity and the ripple non-uniformity.
Compressive Strength Evaluation in Brazed ZrO2/Ti6Al4V Joints Using Finite Element Analysis
Sharma, Ashutosh; Kee, Se Ho; Jung, Flora; Heo, Yongku; Jung, Jae Pil
2016-05-01
This study aims to synthesize and evaluate the compressive strength of the ZrO2/Ti-6Al-4V joint brazed using an active metal filler Ag-Cu-Sn-Ti, and its application to dental implants assuring its reliability to resist the compressive failure in the actual oral environment. The brazing was performed at a temperature of 750 °C for 30 min in a vacuum furnace under 5 × 10-6 Torr atmosphere. The microstructure of the brazed joint showed the presence of an Ag-rich matrix and a Cu-rich phase, and Cu-Ti intermetallic compounds were observed along the Ti-6Al-4V bonded interface. The compressive strength of the brazed ZrO2/Ti-6Al-4V joint was measured by EN ISO 14801 standard test method. The measured compressive strength of the joint was ~1477 MPa—a value almost five times that of existing dental cements. Finite element analysis also confirmed the high von Mises stress values. The compressive strains in the samples were found concentrated near the Ti-6Al-4V position, matching with the position of the real fractured sample. These results suggest extremely significant compressive strength in ZrO2/Ti-6Al-4V joints using the Ag-Cu-Sn-Ti filler. It is believed that a highly reliable dental implant can be processed and designed using the results of this study.
Parallel processing and non-uniform grids in global air quality modeling
Berkvens, P.J.F.; Bochev, Mikhail A.
2002-01-01
A large-scale global air quality model, running efficiently on a single vector processor, is enhanced to make more realistic and more long-term simulations feasible. Two strategies are combined: non-uniform grids and parallel processing. The communication through the hierarchy of non-uniform grids
Luecke, William E.; Ma, Li; Graham, Stephen M.; Adler, Matthew A.
2010-01-01
Ten commercial laboratories participated in an interlaboratory study to establish the repeatability and reproducibility of compression strength tests conducted according to ASTM International Standard Test Method E9. The test employed a cylindrical aluminum AA2024-T351 test specimen. Participants measured elastic modulus and 0.2 % offset yield strength, YS(0.2 % offset), using an extensometer attached to the specimen. The repeatability and reproducibility of the yield strength measurement, expressed as coefficient of variations were cv(sub r)= 0.011 and cv(sub R)= 0.020 The reproducibility of the test across the laboratories was among the best that has been reported for uniaxial tests. The reported data indicated that using diametrically opposed extensometers, instead of a single extensometer doubled the precision of the test method. Laboratories that did not lubricate the ends of the specimen measured yield stresses and elastic moduli that were smaller than those measured in laboratories that lubricated the specimen ends. A finite element analysis of the test specimen deformation for frictionless and perfect friction could not explain the discrepancy, however. The modulus measured from stress-strain data were reanalyzed using a technique that finds the optimal fit range, and applies several quality checks to the data. The error in modulus measurements from stress-strain curves generally increased as the fit range decreased to less than 40 % of the stress range.
Study on the compressive strength of fly ash based geo polymer concrete
Anand Khanna, Pawan; Kelkar, Durga; Papal, Mahesh; Sekar, S. K.
2017-11-01
Introduction of the alternative materials for complete replacement of cement in ordinary concrete will play an important role to control greenhouse gas and its effect. The 100% replacement of binder with fly ash (in integration with potassium hydroxide (koh) and potassium silicate (k2sio3) solutions) in concrete gives a significant alternative to conventional cement concrete. This paper focuses on the effect of alkaline solutions koh and k2sio3 on strength properties of fly ash based geo polymer concrete (fgpc); compared the strength at different molarities of alkaline activator koh at different curing temperature. Fly ash based geo polymer concrete was produced from low calcium fly ash, triggered by addition of koh and k2sio3 solution and by assimilation of superplasticizer for suitable workability. The molarities of potassium hydroxide as 8m, 10m and 12m molarities were used at various curing temperatures such as 60°c, 70 °c and 80°c. Results showed that for given proportion to get maximum compressive strength the optimum molarity of alkaline solution is 12m and optimum curing temperature is 70 °c.
Directory of Open Access Journals (Sweden)
2016-11-01
Full Text Available The paper presents the report of an investigation into the model development and optimization of the compressive strength of 55/45 to 70/30 cement/Rice Husk Ash (RHA in hollow sandcrete block. The low cost and local availability potential of RHA, a pozzolanic material gasps for exploitation. The study applies the Scheffe\\'s optimization approach to obtain a mathematical model of the form f(xi1 ,xi2 ,xi3 xi4 , where x are proportions of the concrete components, viz: cement, RHA, sand and water. Scheffe\\'s i experimental design techniques are followed to mould various hollow block samples measuring 450mm x 225mm x 150mm and tested for 28 days strength. The task involved experimentation and design, applying the second order polynomial characterization process of the simplex lattice method. The model adequacy is checked using the control factors. Finally, a software is prepared to handle the design computation process to take the desired property of the mix, and generate the optimal mix ratios. Reversibly, any mix ratios can be desired and the attainable strength obtained.
Liu, Hai-Zheng; Shi, Ze-Lin; Feng, Bin; Hui, Bin; Zhao, Yao-Hong
2016-03-01
Integrating microgrid polarimeters on focal plane array (FPA) of an infrared detector causes non-uniformity of polarization response. In order to reduce the effect of polarization non-uniformity, this paper constructs an experimental setup for capturing raw flat-field images and proposes a procedure for acquiring non-uniform calibration (NUC) matrix and calibrating raw polarization images. The proposed procedure takes the incident radiation as a polarization vector and offers a calibration matrix for each pixel. Both our matrix calibration and two-point calibration are applied to our mid-wavelength infrared (MWIR) polarization imaging system with integrated microgrid polarimeters. Compared with two point calibration, our matrix calibration reduces non-uniformity by 30 40% under condition of flat-field data test with polarization. The ourdoor scene observation experiment indicates that our calibration can effectively reduce polarization non-uniformity and improve the image quality of our MWIR polarization imaging system.
Optimization of compressive strength in admixture-reinforced cement-based grouts
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Sahin Zaimoglu, A.
2007-12-01
Full Text Available The Taguchi method was used in this study to optimize the unconfined (7-, 14- and 28-day compressive strength of cement-based grouts with bentonite, fly ash and silica fume admixtures. The experiments were designed using an L16 orthogonal array in which the three factors considered were bentonite (0%, 0.5%, 1.0% and 3%, fly ash (10%, 20%, 30% and 40% and silica fume (0%, 5%, 10% and 20% content. The experimental results, which were analyzed by ANOVA and the Taguchi method, showed that fly ash and silica fume content play a significant role in unconfined compressive strength. The optimum conditions were found to be: 0% bentonite, 10% fly ash, 20% silica fume and 28 days of curing time. The maximum unconfined compressive strength reached under the above optimum conditions was 17.1 MPa.En el presente trabajo se ha intentado optimizar, mediante el método de Taguchi, las resistencias a compresión (a las edades de 7, 14 y 28 días de lechadas de cemento reforzadas con bentonita, cenizas volantes y humo de sílice. Se diseñaron los experimentos de acuerdo con un arreglo ortogonal tipo L16 en el que se contemplaban tres factores: la bentonita (0, 0,5, 1 y 3%, las cenizas volantes (10, 20, 30 y 40% y el humo de sílice (0, 5, 10 y 20% (porcentajes en peso del sólido. Los datos obtenidos se analizaron con mediante ANOVA y el método de Taguchi. De acuerdo con los resultados experimentales, el contenido tanto de cenizas volantes como de humo de sílice desempeña un papel significativo en la resistencia a compresión. Por otra parte, las condiciones óptimas que se han identificado son: 0% bentonita, 10% cenizas volantes, 20% humo de sílice y 28 días de tiempo de curado. La resistencia a compresión máxima conseguida en las anteriores condiciones era de 17,1 MPa.
Energy Technology Data Exchange (ETDEWEB)
Uswatta, Suren P.; Okeke, Israel U. [Department of Bioengineering, The University of Toledo, Toledo, OH 43614 (United States); Jayasuriya, Ambalangodage C., E-mail: a.jayasuriya@utoledo.edu [Department of Bioengineering, The University of Toledo, Toledo, OH 43614 (United States); Department of Orthopaedic Surgery, The University of Toledo, Toledo, OH 43614 (United States)
2016-12-01
In this study we have fabricated porous injectable spherical scaffolds using chitosan biopolymer, sodium tripolyphosphate (TPP) and nano-hydroxyapatite (nHA). TPP was primarily used as an ionic crosslinker to crosslink nHA/chitosan droplets. We hypothesized that incorporating nHA into chitosan could support osteoconduction by emulating the mineralized cortical bone structure, and improve the Ultimate Compressive Strength (UCS) of the scaffolds. We prepared chitosan solutions with 0.5%, 1% and 2% (w/v) nHA concentration and used simple coacervation and lyophilization techniques to obtain spherical scaffolds. Lyophilized spherical scaffolds had a mean diameter of 1.33 mm (n = 25). Further, portion from each group lyophilized scaffolds were soaked and dried to obtain Lyophilized Soaked and Dried (LSD) scaffolds. LSD scaffolds had a mean diameter of 0.93 mm (n = 25) which is promising property for the injectability. Scanning Electron Microscopy images showed porous surface morphology and interconnected pore structures inside the scaffolds. Lyophilized and LSD scaffolds had surface pores < 10 and 2 μm, respectively. 2% nHA/chitosan LSD scaffolds exhibited UCS of 8.59 MPa compared to UCS of 2% nHA/chitosan lyophilized scaffolds at 3.93 MPa. Standardize UCS values were 79.98 MPa and 357 MPa for 2% nHA/chitosan lyophilized and LSD particles respectively. One-way ANOVA results showed a significant increase (p < 0.001) in UCS of 1% and 2% nHA/chitosan lyophilized scaffolds compared to 0% and 0.5% nHA/chitosan lyophilized scaffolds. Moreover, 2% nHA LSD scaffolds had significantly increased (p < 0.005) their mean UCS by 120% compared to 2% nHA lyophilized scaffolds. In a drawback, all scaffolds have lost their mechanical properties by 95% on the 2nd day when fully immersed in phosphate buffered saline. Additionally live and dead cell assay showed no cytotoxicity and excellent osteoblast attachment to both lyophilized and LSD scaffolds at the end of 14th day of in vitro
International Nuclear Information System (INIS)
Uswatta, Suren P.; Okeke, Israel U.; Jayasuriya, Ambalangodage C.
2016-01-01
In this study we have fabricated porous injectable spherical scaffolds using chitosan biopolymer, sodium tripolyphosphate (TPP) and nano-hydroxyapatite (nHA). TPP was primarily used as an ionic crosslinker to crosslink nHA/chitosan droplets. We hypothesized that incorporating nHA into chitosan could support osteoconduction by emulating the mineralized cortical bone structure, and improve the Ultimate Compressive Strength (UCS) of the scaffolds. We prepared chitosan solutions with 0.5%, 1% and 2% (w/v) nHA concentration and used simple coacervation and lyophilization techniques to obtain spherical scaffolds. Lyophilized spherical scaffolds had a mean diameter of 1.33 mm (n = 25). Further, portion from each group lyophilized scaffolds were soaked and dried to obtain Lyophilized Soaked and Dried (LSD) scaffolds. LSD scaffolds had a mean diameter of 0.93 mm (n = 25) which is promising property for the injectability. Scanning Electron Microscopy images showed porous surface morphology and interconnected pore structures inside the scaffolds. Lyophilized and LSD scaffolds had surface pores < 10 and 2 μm, respectively. 2% nHA/chitosan LSD scaffolds exhibited UCS of 8.59 MPa compared to UCS of 2% nHA/chitosan lyophilized scaffolds at 3.93 MPa. Standardize UCS values were 79.98 MPa and 357 MPa for 2% nHA/chitosan lyophilized and LSD particles respectively. One-way ANOVA results showed a significant increase (p < 0.001) in UCS of 1% and 2% nHA/chitosan lyophilized scaffolds compared to 0% and 0.5% nHA/chitosan lyophilized scaffolds. Moreover, 2% nHA LSD scaffolds had significantly increased (p < 0.005) their mean UCS by 120% compared to 2% nHA lyophilized scaffolds. In a drawback, all scaffolds have lost their mechanical properties by 95% on the 2nd day when fully immersed in phosphate buffered saline. Additionally live and dead cell assay showed no cytotoxicity and excellent osteoblast attachment to both lyophilized and LSD scaffolds at the end of 14th day of in vitro
Usman, Aliyu; Ibrahim, Muhammad B.; Bala, Nura
2018-04-01
This research is aimed at investigating the effect of using amorphous silica ash (ASA) obtained from rice husk as a partial replacement of ordinary Portland cement (OPC) on the compressive and flexural strength of mortar. ASA was used in partial replacement of ordinary Portland cement in the following percentages 2.5 percent, 5 percent, 7.5 percent and 10 percent. These partial replacements were used to produce Cement-ASA mortar. ASA was found to contain all major chemical compounds found in cement with the exception of alumina, which are SiO2 (91.5%), CaO (2.84%), Fe2O3 (1.96%), and loss on ignition (LOI) was found to be 9.18%. It also contains other minor oxides found in cement. The test on hardened mortar were destructive in nature which include flexural strength test on prismatic beam (40mm x 40mm x 160mm) and compressive strength test on the cube size (40mm x 40mm, by using the auxiliary steel plates) at 2,7,14 and 28 days curing. The Cement-ASA mortar flexural and compressive strengths were found to be increasing with curing time and decreases with cement replacement by ASA. It was observed that 5 percent replacement of cement with ASA attained the highest strength for all the curing ages and all the percentage replacements attained the targeted compressive strength of 6N/mm2 for 28 days for the cement mortar
Ayorinde, J O; Itiola, O A; Odeniyi, M A
2013-03-01
A work has been done to study the effects of material properties and compression speed on microbial survival and tensile strength in diclofenac tablet formulations. Tablets were produced from three formulations containing diclofenac and different excipients (DC, DL and DDCP). Two types of machines (Hydraulic hand press and single punch press), which compress the tablets at different speeds, were used. The compression properties of the tablets were analyzed using Heckel and Kawakita equations. A 3-dimensional plot was produced to determine the relationship between the tensile strength, compression speed and percentage survival of Bacillus subtilis in the diclofenac tablets. The mode of consolidation of diclofenac was found to depends on the excipient used in the formulation. DC deformed mainly by plastic flow with the lowest Py and Pk values. DL deformed plastically at the initial stage, followed by fragmentation at the later stage of compression, whereas DDCP deformed mainly by fragmentation with the highest Py and Pk values. The ranking of the percentage survival of B. subtilis in the formulations was DDCP > DL > DC, whereas the ranking of the tensile strength of the tablets was DDCP > DL > DC. Tablets produced on a hydraulic hand press with a lower compression speed had a lower percentage survival of microbial contaminants than those produced on a single punch press, which compressed the tablets at a much higher speed. The mode of consolidation of the materials and the speed at which tablet compression is carried out have effects on both the tensile strength of the tablets and the extent of destruction of microbial contaminants in diclofenac tablet formulations.
ALKALI-ACTIVATION KINETICS OF PHOSPHORUS SLAG CEMENT USING COMPRESSIVE STRENGTH DATA
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Hojjatollah Maghsoodloorad
2015-09-01
Full Text Available In this research, through compressive strength data, the order and kinetics of alkali-activation of phosphorus slag activated with two compound activators of NaOH + Na2CO3 and Na2CO3 + Ca(OH2, has been evaluated. The kinetics and order of alkali activation is a key factor to forecasting the mechanical behavior of alkali activated cement at different curing time and temperatures without carrying out experimental tests. The apparent activation energy was obtained as 35.6 kJ.mol-1 and 60.7 kJ.mol-1 for the two activators, respectively. Investigations proved that the alkali-activation kinetics of phosphorus slag resembles chemical reactions of second order. Moreover, the order of alkali-activation of phosphorus slag does not depend on the type of activator.
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Auday A Mehatlaf
2017-12-01
Full Text Available Cement Klin Dust (CKD was the waste of almost cement industry factories, so that in this paper utilization of CKD as filler in cement and/or concrete was the main objective. CKD from the Karbala cement factory had been used and analysis to know the chemical composition of the oxides was done. In this paper cement mortars with different weight percentages of CKD (0,5,10,20,30,40 had been prepared. Physical properties such as density and porosity were done in different age curing (3, 7, 28 day. In addition, mechanical properties included the coefficient of thermal conductivity and compressive strength had also observed with different age (3,7, and 28 for all prepared specimens. From the obtained the experimental results and their discussion, it was clear that the addition (20% of CKD had the good results in cement mortars.
International Nuclear Information System (INIS)
Walsh, D; Hall, S R; Wimbush, S C
2008-01-01
Templated control of crystallization by biopolymers is a new technique in the synthesis of high temperature superconducting phases. By controlling the way YBa 2 Cu 3 O 7-δ (Y123) materials crystallize and are organized in three dimensions, the critical current density can be improved. In this work, we present the results of doping superconducting sponges with calcium ions, which result in higher critical current densities (J c ) and improved compressive strength compared to that of commercially available Y123, in spite of minor reductions in T c . Y123 synthesis using the biopolymer dextran achieves not only an extremely effective oxygenation of the superconductor but also an in situ template-directing of the crystal morphology producing high J c , homogeneous superconducting structures with nano-scale crystallinity
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Waldemir Rodrigues
2004-06-01
Full Text Available The durability of wood is affected by several factors. For this reason, much research has been done on a variety of chemical compounds for impregnating wood, aimed at preserving it while simultaneously improving its properties. Recent studies of the properties of impregnated wood have demonstrated the possibility of substantially improving its mechanical characteristics. Thus, the purpose of this work was to compare the strength to parallel compression of wooden fibers (Eucalyptus grandis, both nonimpregnated and impregnated with a monocomponent resin, from the standpoint of pressure and impregnation time, aiming at its structural utilization. The results demonstrate that the compressive strength of impregnated test specimens is greater than that of nonimpregnated ones, indicating that monocomponent polyurethane resin can be considered suitable for impregnating wood, since it increases the compressive strength of eucalyptus.
Khed, Veerendrakumar C.; Mohammed, Bashar S.; Fadhil Nuruddin, Muhd
2018-04-01
The different sizes of crumb rubber have been used to investigate the effects on flowability and the compressive strength of the hybrid fibre reinforced engineered cementitious composite. Two sizes of crumb rubber 30 mesh and 1 to 3mm were used in partial replacement with the fine aggregate up to 60%. The experimental study was carried out through mathematical and statistical analysis by response surface methodology (RSM) using the Design Expert software. The response models have been developed and the results were validated by analysis of variance (ANOVA). It was found that finer sized crumb rubber inclusion had produced better workability and higher compressive strength when compared to the larger size and it was concluded that crumb rubber has negative effect on compressive strength and positive effect on workability. The optimization results are found to an approximately good agreement with the experimental results.
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Yun-Hoo Lee
2013-01-01
Full Text Available This study investigates the compressive strength of natural gas hydrate (NGH pellet strip extruded from die holes of a twin-roll press for continuous pelletizing (TPCP. The lab-scale TPCP was newly developed, where NGH powder was continuously fed and extruded into strip-type pellet between twin rolls. The system was specifically designed for future expansion towards mass production of solid form NGH. It is shown that the compressive strength of NGH pellet strip heavily depends on parameters in the extrusion process, such as feeding pressure, pressure ratio, and rotational speed. The mechanism of TPCP, along with the compressive strength and density of pellets, is discussed in terms of its feasibility for producing NGH pellets in the future.
Experimental Study on Unconfined Compressive Strength of Organic Polymer Reinforced Sand
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Jin Liu
2018-01-01
Full Text Available The natural sand is loose in structure with a small cohesive force. Organic polymer can be used to reinforce this sand. To assess the effectiveness of organic polymer as soil stabilizer (PSS, a series of unconfined compressive strength tests have been performed on reinforced sand. The focus of this study was to determine a curing method and a mix design to stabilize sand. The curing time, PSS concentration, and sand density were considered as variables in this study. The reinforcement mechanism was analyzed with images of scanning electron microscope (SEM. The results indicated that the strength of stabilized sand increased with the increase in the curing time, concentration, and sand density. The strength plateaus are at about curing time of 48 h. The UCS of samples with density of 1.4 g/cm3 at 10%, 20%, 30%, 40%, and 50% PSS concentration are 62.34 kPa, 120.83 kPa, 169.22 kPa, 201.94 kPa, and 245.28 kPa, respectively. The UCS of samples with PSS concentration of 30% at 1.4 g/cm3, 1.5 g/cm3, and 1.6 g/cm3 density are 169.22 kPa, 238.6 kPa 5, and 281.69 kPa, respectively. The chemical reaction between PSS and sand particle is at its microlevel, which improves the sand strength by bonding its particles together and filling the pore spaces. In comparison with the traditional reinforcement methods, PSS has the advantages of time saving, lower cost, and better environment protection. The research results can be useful for practical engineering applications, especially for reinforcement of foundation, embankment, and landfill.
SHEAR STRENGTH, COLLAPSIBILITY AND COMPRESSIBILITY CHARACTERISTICS OF COMPACTED BAIJI DUNE SOILS
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ABBAS JAWAD AL-TAIE
2017-03-01
Full Text Available Baiji city is a vital industrial centre in Iraq since it has the biggest oil refinery. Therefore, Baiji has become an attractive site for strategic construction projects. Dune sand covers about 220 km2 of the area of Baiji city. However, few researches had attempted to study its behaviour. In this study laboratory tests were conducted to determine the shear strength, collapsibility and compressibility of the dune sand at its natural and compacted status. The effect of dry unit weight, moisture content, relative density and soaking on mechanical properties of dune soil was investigated. The results demonstrated that dry and soaked dune specimens tested at their in-situ condition exhibited similar volume changes during shear and identical friction angles. The results of shear tests of both of compacted soaked and unsoaked samples were identical. The collapse potential of dune soil is inversely proportional with the relative density. The minimum axial strain is observed when the samples are compacted to modified effort. The compression index of the compacted specimens is affected by moulding water content, while the rebound index is less sensitive.
Choo, Hyunwook; Nam, Hongyeop; Lee, Woojin
2017-12-01
The composition of naturally cemented deposits is very complicated; thus, estimating the maximum shear modulus (Gmax, or shear modulus at very small strains) of cemented sands using the previous empirical formulas is very difficult. The purpose of this experimental investigation is to evaluate the effects of particle size and cement type on the Gmax and unconfined compressive strength (qucs) of cemented sands, with the ultimate goal of estimating Gmax of cemented sands using qucs. Two sands were artificially cemented using Portland cement or gypsum under varying cement contents (2%-9%) and relative densities (30%-80%). Unconfined compression tests and bender element tests were performed, and the results from previous studies of two cemented sands were incorporated in this study. The results of this study demonstrate that the effect of particle size on the qucs and Gmax of four cemented sands is insignificant, and the variation of qucs and Gmax can be captured by the ratio between volume of void and volume of cement. qucs and Gmax of sand cemented with Portland cement are greater than those of sand cemented with gypsum. However, the relationship between qucs and Gmax of the cemented sand is not affected by the void ratio, cement type and cement content, revealing that Gmax of the complex naturally cemented soils with unknown in-situ void ratio, cement type and cement content can be estimated using qucs.
Prediction of zeolite-cement-sand unconfined compressive strength using polynomial neural network
MolaAbasi, H.; Shooshpasha, I.
2016-04-01
The improvement of local soils with cement and zeolite can provide great benefits, including strengthening slopes in slope stability problems, stabilizing problematic soils and preventing soil liquefaction. Recently, dosage methodologies are being developed for improved soils based on a rational criterion as it exists in concrete technology. There are numerous earlier studies showing the possibility of relating Unconfined Compressive Strength (UCS) and Cemented sand (CS) parameters (voids/cement ratio) as a power function fits. Taking into account the fact that the existing equations are incapable of estimating UCS for zeolite cemented sand mixture (ZCS) well, artificial intelligence methods are used for forecasting them. Polynomial-type neural network is applied to estimate the UCS from more simply determined index properties such as zeolite and cement content, porosity as well as curing time. In order to assess the merits of the proposed approach, a total number of 216 unconfined compressive tests have been done. A comparison is carried out between the experimentally measured UCS with the predictions in order to evaluate the performance of the current method. The results demonstrate that generalized polynomial-type neural network has a great ability for prediction of the UCS. At the end sensitivity analysis of the polynomial model is applied to study the influence of input parameters on model output. The sensitivity analysis reveals that cement and zeolite content have significant influence on predicting UCS.
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Abdulsalam Arafa Salaheddin
2017-01-01
Full Text Available The production of ordinary Portland cement (OPC consumes considerable natural resources and energy, and it also affects the emission of a significant quantity of CO2 in the atmosphere. This pervious geopolymer concrete study aims to explore an alternative binder without OPC. Pervious geopolymer concretes were prepared from fly ash (FA, sodium silicate (NaSiO3, sodium hydroxide (NaOH solution, and coarse aggregate (CA. The effects of pervious geopolymer concrete parameters that affect water permeability and compressive strength are evaluated. The FA to CA ratios of 1:6, 1:7,1:8, and 1:9 by weight, CA sizes of 5–10, 10–14, and 14–20 mm, constant NaSiO3/NaOH ratio of 2.5, alkaline liquid to fly ash (AL/FA ratios of 0.4, 0.5, and 0.6, and NaOH concentrations of 8, 10, and 12 M were the pervious geopolymer concrete mix proportions. The curing temperature of 80 °C for 24 h was used. The results showed that a pervious geopolymer concrete with CA of 10 mm achieved water permeability of 2.3 cm/s and compressive strength of 20 MPa with AL/FA ratio of 0.5, NaOH concentration of 10 M, and FA:CA of 1:7. GEOCRETE is indicated to have better engineering properties than does pervious concrete that is made of ordinary Portland cement.
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M. Scafè
2014-07-01
Full Text Available In this work has been estimated the compressive strength of a unidirectional lamina of a carbon/epoxy composite material, using the cross-ply and angle-ply laminates. Over the years various methods have been developed to deduce compressive properties of composite materials reinforced with long fibres. Each of these methods is characterized by a specific way of applying load to the specimen. The method chosen to perform the compression tests is the Wyoming Combined Loading Compression (CLC Test Method, described in ASTM D 6641 / D 6641M-09. This method presents many advantages, especially: the load application on the specimen (end load combined with shear load, the reproducibility of measurements and the experimental equipment quite simplified. Six different laminates were tested in compressive tests. They were realized by the same unidirectional prepreg, but with different stacking sequences: two cross-ply [0/90]ns, two angle-ply [0/90/±45]ns and two unidirectional laminates [0]ns and [90]ns. The estimate of the compressive strength of the unidirectional laminates at 0°, was done by an indirect analytical method, developed from the classical lamination theory, and which uses a multiplicative parameter known as Back-out Factor (BF. The BF is determined by using the experimental values obtained from compression tests.
Jurowski, Krystian; Grzeszczyk, Stefania
2018-03-22
In this paper, the relationship between the static and dynamic elastic modulus of concrete and the relationship between the static elastic modulus and compressive strength of concrete have been formulated. These relationships are based on investigations of different types of concrete and take into account the type and amount of aggregate and binder used. The dynamic elastic modulus of concrete was tested using impulse excitation of vibration and the modal analysis method. This method could be used as a non-destructive way of estimating the compressive strength of concrete.
Jurowski, Krystian; Grzeszczyk, Stefania
2018-01-01
In this paper, the relationship between the static and dynamic elastic modulus of concrete and the relationship between the static elastic modulus and compressive strength of concrete have been formulated. These relationships are based on investigations of different types of concrete and take into account the type and amount of aggregate and binder used. The dynamic elastic modulus of concrete was tested using impulse excitation of vibration and the modal analysis method. This method could be used as a non-destructive way of estimating the compressive strength of concrete. PMID:29565830
Brizzio, Eugenio; Amsler, Felix; Lun, Bertrand; Blättler, Werner
2010-02-01
To compare the proportion and rate of healing, pain, and quality of life of low-strength medical compression stockings (MCS) with traditional bandages applied for the treatment of recalcitrant venous leg ulcers. A single-center, randomized, open-label study was performed with consecutive patients. Sigvaris prototype MCS providing 15 mm Hg-25 mm Hg at the ankle were compared with multi-layer short-stretch bandages. In both groups, pads were placed above incompetent perforating veins in the ulcer area. The initial static pressure between the dressing-covered ulcer and the pad was 29 mm Hg and 49 mm Hg with MCS and bandages, respectively. Dynamic pressure measurements showed no difference. Compression was maintained day and night and changed every week. The primary endpoint was healing within 90 days. Secondary endpoints were healing within 180 days, time to healing, pain (weekly Likert scales), and monthly quality of life (ChronIc Venous Insufficiency Quality of Life [CIVIQ] questionnaire). Of 74 patients screened, 60 fulfilled the selection criteria and 55 completed the study; 28 in the MCS and 27 in the bandage group. Ulcers were recurrent (48%), long lasting (mean, 27 months), and large (mean, 13 cm2). All but one patient had deep venous reflux and/or incompetent perforating veins in addition to trunk varices. Characteristics of patients and ulcers were evenly distributed (exception: more edema in the MCS group; P = .019). Healing within 90 days was observed in 36% with MCS and in 48% with bandages (P = .350). Healing within 180 days was documented in 50% with MCS and in 67% with bandages (P = .210). Time to healing was identical. Pain scored 44 and 46 initially (on a scale in which 100 referred to maximum and 0 to no pain) and decreased within the first week to 20 and 28 in the MCS and bandage groups, respectively (P ulcers only. Our study illustrates the difficulty of bringing large and long-standing venous ulcers to heal. The effect of compression with MCS was
Prasanna Venkatesh, G. J.; Vivek, S. S.; Dhinakaran, G.
2017-07-01
In the majority of civil engineering applications, the basic building blocks were the masonry units. Those masonry units were developed as a monolithic structure by plastering process with the help of binding agents namely mud, lime, cement and their combinations. In recent advancements, the mortar study plays an important role in crack repairs, structural rehabilitation, retrofitting, pointing and plastering operations. The rheology of mortar includes flowable, passing and filling properties which were analogous with the behaviour of self compacting concrete. In self compacting (SC) mortar cubes, the cement was replaced by mineral admixtures namely silica fume (SF) from 5% to 20% (with an increment of 5%), metakaolin (MK) from 10% to 30% (with an increment of 10%) and ground granulated blast furnace slag (GGBS) from 25% to 75% (with an increment of 25%). The ratio between cement and fine aggregate was kept constant as 1: 2 for all normal and self compacting mortar mixes. The accelerated curing namely electric oven curing with the differential temperature of 128°C for the period of 4 hours was adopted. It was found that the compressive strength obtained from the normal and electric oven method of curing was higher for self compacting mortar cubes than normal mortar cube. The cement replacement by 15% SF, 20% MK and 25%GGBS obtained higher strength under both curing conditions.
Vashisht, Rajneesh; Attri, Sampan; Sharma, Deepak; Shukla, Abhilash; Goel, Gunjan
2018-03-01
The present study reports the potential of newly isolated calcite precipitating bacteria isolated from alluvial soil to improve the strength and durability of concrete. A total of sixteen samples of alluvial soil and sewage were collected from the different locations of province Solan (India). For isolation, enrichment culture technique was used to enrich calcite precipitating strains in Urea broth. After enrichment, fourteen distinct bacterial strains were obtained on Urea agar. Based on qualitative and quantitative screening for urease activity, five isolates were obtained possessing higher calcite formation and urease activities (38-77 μmhos/cm) as compared with standard strain of Bacillus megaterium MTCC 1684 (77 μmhos/cm). An isolate I13 identified as Lysinibacillus sp. was selected for self healing property in the concrete mix of M20. An improved compressive strength of 1.5 fold was observed in concrete samples amended with Lysinibacillus sp. over the concrete amended with B. megaterium MTCC 1684 after 28 days of curing. The higher calcite precipitation activity was indicated in Lysinibacillus sp. by FE-SEM micrographs and EDX analysis. Copyright © 2017 Elsevier GmbH. All rights reserved.
Effect of Microwave Disinfection on Compressive and Tensile Strengths of Dental Stones
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Mahmood Robati Anaraki
2013-03-01
Full Text Available Background and aims. Although microwave irradiation has been used for disinfection of dental stone casts, there are concerns regarding mechanical damage to casts during the process. The aim of this study was to evaluate the effect of microwave irradiation on the compressive strength (CS and diametral tensile strength (DTS of stone casts. Materials and methods. In this in vitro study, 80 cylindrical type III and IV stone models (20 × 40 mm were prepared and divided into 8 groups of 10. The DTS and CS of the specimens were measured by a mechanical testing machine at a crosshead speed of 0.5 cm/min after 7 times of frequent wetting, irradiating at an energy level of 600 W for 3 minutes and cooling. Data were analyzed by Student’s t-test. Results. Microwave irradiation significantly increased DTS of type III and IV to 5.23 ± 0.64 and 8.17 ± 0.94, respectively (P < 0.01. Conclusion. According to the results, microwave disinfection increases DTS of type III and IV stone casts without any effects on their CS.
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Mydin M.A.O.
2014-01-01
Full Text Available This study investigated the performance of the properties of foamed concrete in replacing volumes of cement of 10%, 15% and 20% by weight. A control unit of foamed concrete mixture made with ordinary Portland cement (OPC and 10%, 15% and 20% silica fume was prepared. Three mechanical property parameters were studied such as compressive strength, flexural strength and splitting tensile of foamed concrete with different percentages of silica fume. Silica fume is commonly used to increase the mechanical properties of concrete materials and it is also chosen due to certain economic reasons. The foamed concrete used in this study was cured at a relative humidity of 70% and a temperature of ±28°C. The improvement of mechanical properties was due to a significant densification in the microstructure of the cement paste matrix in the presence of silica fume hybrid supplementary binder as observed from micrographs obtained in the study. The overall results showed that there is a potential to utilize silica fume in foamed concrete, as there was a noticeable enhancement of thermal and mechanical properties with the addition of silica fume.
Winnard, B. R.; Mitchell, T. M.; Browning, J.; Cuss, R. J.; Norris, S.; Meredith, P. G.
2017-12-01
Deep geological repositories are the preferred solution to dispose of radioactive waste; design concepts for these disposal facilities include compacted, saturated bentonite as a buffer between waste canister and host rock. Bentonite is favoured for its high swelling capacity, low permeability, and radionuclide retention properties. However, its thermo-hydro-mechanical tolerances must be thoroughly tested to ensure adequate long term performance. Climate variations are likely to induce periods of permafrost, and consequently, changes in groundwater salinity at depth. We performed laboratory experiments investigating effects of temperature and salinity change on uniaxial compressive strength (UCS), and permeability of compacted MX-80 bentonite cylinders. These specimens (moisture content = 22.9±0.1%, dry density = 1.66±0.02 g.cm-3) were compacted with deionised water, and a range of wt% NaCl, CaCl2, or KCl, to compare the effects of compaction fluid. Samples of compressed bentonite were cooled to -20 °C, and heated to 90 ºC, a possible temperature forecast for a repository dependent on factors such as geographical location, waste type, and facility design. Tests were all performed at room temperature, however in situ temperature tests are planned. The UCS of samples that experienced freeze thaw, and 40 ºC treatment failed at 6.5 MPa, with 4% strain, maintaining the same values as untreated bentonite compacted with deionised water. Samples compacted with saline solutions also yielded similar strengths, of 7 MPa, and failed at 4%. However, the 90 ºC, regardless of compaction fluid, failed at 15-18 MPa, at just 2% strain. In all experiments, the spread of strain accommodated varied inconsistently, however, peak stress was uniform. Further experiments into heterogeneity are needed to understand the responsible mechanisms. To obtain permeability, we utilised the pore pressure oscillation (PPO) technique with argon as the pore fluid. We also tested water as the pore
Photoionization microscopy of Rydberg hydrogen atom in a non-uniform electrical field
International Nuclear Information System (INIS)
Cheng Shao-Hao; Wang De-Hua; Chen Zhao-Hang; Chen Qiang
2016-01-01
In this paper, we investigate the photoionization microscopy of the Rydberg hydrogen atom in a gradient electric field for the first time. The observed oscillatory patterns in the photoionization microscopy are explained within the framework of the semiclassical theory, which can be considered as a manifestation of interference between various electron trajectories arriving at a given point on the detector plane. In contrast with the photoionization microscopy in the uniform electric field, the trajectories of the ionized electron in the gradient electric field will become chaotic. An infinite set of different electron trajectories can arrive at a given point on the detector plane, which makes the interference pattern of the electron probability density distribution extremely complicated. Our calculation results suggest that the oscillatory pattern in the electron probability density distribution depends sensitively on the electric field gradient, the scaled energy and the position of the detector plane. Through our research, we predict that the interference pattern in the electron probability density distribution can be observed in an actual photoionization microscopy experiment once the external electric field strength and the position of the electron detector plane are reasonable. This study provides some references for the future experimental research on the photoionization microscopy of the Rydberg atom in the non-uniform external fields. (paper)
Structural strength of cancellous specimens from bovine femur under cyclic compression
Directory of Open Access Journals (Sweden)
Kaori Endo
2016-01-01
Full Text Available The incidence of osteoporotic fractures was estimated as nine million worldwide in 2000, with particular occurrence at the proximity of joints rich in cancellous bone. Although most of these fractures spontaneously heal, some fractures progressively collapse during the early post-fracture period. Prediction of bone fragility during progressive collapse following initial fracture is clinically important. However, the mechanism of collapse, especially the gradual loss of the height in the cancellous bone region, is not clearly proved. The strength of cancellous bone after yield stress is difficult to predict since structural and mechanical strength cannot be determined a priori. The purpose of this study was to identify whether the baseline structure and volume of cancellous bone contributed to the change in cancellous bone strength under cyclic loading. A total of fifteen cubic cancellous bone specimens were obtained from two 2-year-old bovines and divided into three groups by collection regions: femoral head, neck, and proximal metaphysis. Structural indices of each 5-mm cubic specimen were determined using micro-computed tomography. Specimens were then subjected to five cycles of uniaxial compressive loading at 0.05 mm/min with initial 20 N loading, 0.3 mm displacement, and then unloading to 0.2 mm with 0.1 mm displacement for five successive cycles. Elastic modulus and yield stress of cancellous bone decreased exponentially during five loading cycles. The decrease ratio of yield stress from baseline to fifth cycle was strongly correlated with bone volume fraction (BV/TV, r = 0.96, p < 0.01 and structural model index (SMI, r = − 0.81, p < 0.01. The decrease ratio of elastic modulus from baseline to fifth cycle was also correlated with BV/TV (r = 0.80, p < 0.01 and SMI (r = − 0.78, p < 0.01. These data indicate that structural deterioration of cancellous bone is associated with bone strength after yield stress. This study suggests that
Analysis of Quantum Effects in Non-Uniformly Doped MOS Structures
National Research Council Canada - National Science Library
Fiegna, Claudio
1997-01-01
This paper presents results from the self-consistent solution of Schrodinger and Poisson equations obtained in one-dimensional non-uniformly doped MOS structures suitable for the fabrication of very short transistors...
The magnetostriction in a superconductor-magnet system under non-uniform magnetic field
Energy Technology Data Exchange (ETDEWEB)
Li, Xueyi; Jiang, Lang; Wu, Hao [Key Laboratory of Mechanics on Disaster and Environment in Western China attached to the Ministry of Education of China, Lanzhou University, Lanzhou, Gansu 730000 (China); Gao, Zhiwen, E-mail: gaozhw@lzu.edu.cn [Department of Mechanics and Engineering Science, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, Gansu 730000 (China)
2017-03-15
Highlights: • We studied firstly magnetostriction in HTS under non-uniform magnetic field. • The superconductors may be homogeneous and nonhomogeneous. • The magnetostrictions response of the HTS is sensitive to the critical current density and amplitude of the applied magnetic field. • The magnetostriction of nonhomogeneous HTS is larger than that of homogeneous HTS. - Abstract: This paper describes a numerical model to examine the magnetostriction of bulk high-temperature superconductor (HTS) under non-uniform magnetic field in conjunction with finite element analysis. Through this model, the magnetostriction of homogeneous and nonhomogeneous HTS can be implemented under non-uniform magnetic field. Further, the effects of critical current density, applied field frequency and amplitude are also considered. The computational study can provide a fundamental mechanistic understanding the effects of non-uniform magnetic field on magnetostriction of HTS.
International Nuclear Information System (INIS)
Manglos, S.H.; Jaszczak, R.J.; Floyd, C.E.
1988-01-01
A method is developed to improve quantitation in SPECT imaging by using an attenuation compensation method which includes the correct non-uniform attenuation spatial distribution (''map''). The method is based on the technique of weighted back projection, previously developed for uniform attenuation. The method is tested by imaging a non-uniform phantom, reconstructing with the known attenuation map, and quantitatively comparing the resultant image with the known activity distribution. Reconstructed image profiles are dramatically improved in comparison to reconstructions without compensation or with an assumed uniform attenuation map. Contrast measurements further quantify the improvement. Line spread function distortions seen previously in non-uniform geometries are essentially eliminated by the method. Therefore, the method appears to be appropriate for these geometries, if the non-uniform map can be determined. Some additional image distortions introduced by the compensation method are noted and will require further study
Directory of Open Access Journals (Sweden)
FAREED AHMED MEMON
2013-02-01
Full Text Available This paper reports the results of the laboratory tests conducted to investigate the effect of sodium hydroxide concentration on the fresh properties and compressive strength of self-compacting geopolymer concrete (SCGC. The experiments were conducted by varying the concentration of sodium hydroxide from 8 M to 14 M. Test methods such as Slump flow, V-Funnel, L-box and J-Ring were used to assess the workability characteristics of SCGC. The test specimens were cured at 70°C for a period of 48 hours and then kept in room temperature until the day of testing. Compressive strength test was carried out at the ages of 1, 3, 7 and 28 days. Test results indicate that concentration variation of sodium hydroxide had least effect on the fresh properties of SCGC. With the increase in sodium hydroxide concentration, the workability of fresh concrete was slightly reduced; however, the corresponding compressive strength was increased. Concrete samples with sodium hydroxide concentration of 12 M produced maximum compressive strength.
LENUS (Irish Health Repository)
Dowling, Adam H
2012-03-01
Three strength tests (compressive, three point flexure and biaxial) were performed on three glass ionomer (GI) restoratives to assess the most appropriate methodology in terms of validity and reliability. The influence of mixing induced variability on the data sets generated were eliminated by using encapsulated GIs.
International Nuclear Information System (INIS)
Kasmudin; Kusnanto
2002-01-01
The use of the coconut fibres to increase compressive strength of segmentation of zeolites as absorber of Sr-90 liquid waste was studied. The purpose of this research was to find the optimum content and length of fibres that give maximum compressive strength. This research was done with mortar-zeolites specimen of cylinder 2,2 cm diameter and 4,4 cm high, the content of zeolites was 13% volume of specimen, weight ratio of water and cement 0,3, length of fibres 1,5 cm, 2 cm, 2,5 cm, and 3 cm (aspect ratio ± 60, ± 80, ± 100 and ± 120) with the fibres content of each fibre 0%, 0,5%, 0,10%, 0,25%, 0,50%, 0,75%, and 1,00%. Addition of fibres was done with a direction of orientation longitudinal to the specimen. The specimens were tested on 28 days old test specimens. The result showed that addition of coconut fibres until certain content would increase compressive strength. The optimum size of fibres with 92,313 N/MM 2 of compressive strength or increased 119,21% of no fibres specimen were 0,50% of volume and 3 cm in length
Directory of Open Access Journals (Sweden)
W.S.B. Dwandaru
2016-10-01
Full Text Available As the world is growing rapidly, people need better building materials such as mortar. The aim of this research is to determine the effect of adding silver nanoparticle solution towards the porosity and compressive strength of mortar. This research was started by making silver nanoparticle solution from nitrate silver (AgNO3. The solution is then characterized using Uv-Vis spectrophotometer. 5 mM silver nanoparticle is added in the process of mortar production with volume variation of the silver nanoparticle solution. The porosity, compressive strength, and the content of mortar were determined by digital scale, universal testing machine, and X-ray diffraction, respectively. For silver nanoparticle solution volumes of (in mL 0, 5, 10, 15, 20, and 25 the porosity obtained are (in % 20.38, 19.48, 19.42, 18.9, 17.8, and 17.5, respectively. The best increase in compressive strength is obtained for (in MPa 29,068, 29,308, and 31,385, with nanoparticle solution volumes of (in mL 5, 10, and 15 Keywords: mortar, silver nanoparticle, compressive strength
Energy Technology Data Exchange (ETDEWEB)
Nochaiya, Thanongsak [Department of Physics, Faculty of Science, Naresuan University, Phitsanulok 65000 (Thailand); Sekine, Yoshika [Department of Chemistry, School of Science, Tokai University, 4-1-1 Kitakaname, Hiratsuka, Kanagawa 259-1292 (Japan); Choopun, Supab [Applied Physics Research Laboratory, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Chaipanich, Arnon, E-mail: arnon.chaipanich@cmu.ac.th [Advanced Cement-Based Materials Research Unit, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)
2015-05-05
Highlights: • Nano zinc oxide was used as an additive material. • Microstructure and phase characterization of pastes were characterized using SEM and XRD. • TGA and FTIR were also used to determine the hydration reaction. • Compressive strength of ZnO mixes was found to increase at 28 days. - Abstract: Zinc oxide nanoparticles as a nanophotocatalyst has great potential for self-cleaning applications in concrete structures, its effects on the cement hydration, setting time and compressive strength are also important when using it in practice. This paper reports the effects of zinc oxide nanoparticles, as an additive material, on properties of cement-based materials. Setting time, compressive strength and porosity of mortars were investigated. Microstructure and morphology of pastes were characterized using scanning electron microscope and X-ray diffraction (XRD), respectively. Moreover, thermal gravimetric analysis (TGA) and Fourier-transform infrared spectrometer (FTIR) were also used to determine the hydration reaction. The results show that Portland cement paste with additional ZnO was found to slightly increase the water requirement while the setting time presented prolongation period than the control mix. However, compressive strength of ZnO mixes was found to be higher than that of PC mix up to 15% (at 28 days) via filler effect. Microstructure, XRD and TGA results of ZnO pastes show less hydration products before 28 days but similar at 28 days. In addition, FTIR results confirmed the retardation when ZnO was partially added in Portland cement pastes.
Kim, Beom-Su; Kang, Hyo Jin; Lee, Jun
2013-10-01
Cuttlefish bones (CBs) have emerged as attractive biomaterials because of their porous structure and components that can be converted into hydroxyapatite (HAp) via a hydrothermal reaction. However, their brittleness and low strength restrict their application in bone tissue engineering. Therefore, to improve the compressive strength of the scaffold following hydrothermal conversion to a HAp form of CB (CB-HAp), the scaffold was coated using a polycaprolactone (PCL) polymer at various concentrations. In this study, raw CB was successfully converted into HAp via a hydrothermal reaction. We then evaluated their surface properties and composition by scanning electron microscopy and X-ray diffraction analysis. The CB-HAp coated with PCL showed improved compressive performance and retained a microporous structure. The compressive strength was significantly increased upon coating with 5 and 10% PCL, by 2.09- and 3.30-fold, respectively, as compared with uncoated CB-HAp. However, coating with 10% PCL resulted in a reduction in porosity. Furthermore, an in vitro biological evaluation demonstrated that MG-63 cells adhered well, proliferated and were able to be differentiated on the PCL-coated CB-HAp scaffold, which was noncytotoxic. These results suggest that a simple coating method is useful to improve the compressive strength of CB-HAp for bone tissue engineering applications. Copyright © 2013 Wiley Periodicals, Inc.
Directory of Open Access Journals (Sweden)
Jenny Krisnawaty
2014-11-01
Full Text Available Hybrid composites are mostly used on large cavities as restorative dental materials, whether it is used directly or indirectly. The mechanical properties of composite resin shall increase if it is treated with post cure treatment. The aim of this study is to evaluate compressive strength differences between dry heat and Light Emitting Diodes (LED treatment on the hybrid dental composite. A quasi-experimental was applied on this research with a total of 30 samples that were divided into two groups. Each sample was tested using LLOYD Universal Testing Machine with 1 mm/min speed to evaluate the compressive strength. The compressive strength results were marked when the sample was broken. The results of two groups were then analyzed using t-test statistical calculation. The results of this study show that post cure treatment on hybrid composite using LED light box (194.138 MPa was lower than dry heat treatment (227.339 MPa, which was also significantly different from statistical analysis. It can be concluded that compressive strength of LED light box was lower than dry heat post-cure treatment on the hybrid composite resin.
International Nuclear Information System (INIS)
Nochaiya, Thanongsak; Sekine, Yoshika; Choopun, Supab; Chaipanich, Arnon
2015-01-01
Highlights: • Nano zinc oxide was used as an additive material. • Microstructure and phase characterization of pastes were characterized using SEM and XRD. • TGA and FTIR were also used to determine the hydration reaction. • Compressive strength of ZnO mixes was found to increase at 28 days. - Abstract: Zinc oxide nanoparticles as a nanophotocatalyst has great potential for self-cleaning applications in concrete structures, its effects on the cement hydration, setting time and compressive strength are also important when using it in practice. This paper reports the effects of zinc oxide nanoparticles, as an additive material, on properties of cement-based materials. Setting time, compressive strength and porosity of mortars were investigated. Microstructure and morphology of pastes were characterized using scanning electron microscope and X-ray diffraction (XRD), respectively. Moreover, thermal gravimetric analysis (TGA) and Fourier-transform infrared spectrometer (FTIR) were also used to determine the hydration reaction. The results show that Portland cement paste with additional ZnO was found to slightly increase the water requirement while the setting time presented prolongation period than the control mix. However, compressive strength of ZnO mixes was found to be higher than that of PC mix up to 15% (at 28 days) via filler effect. Microstructure, XRD and TGA results of ZnO pastes show less hydration products before 28 days but similar at 28 days. In addition, FTIR results confirmed the retardation when ZnO was partially added in Portland cement pastes
Chigvintsev, A. Yu; Zorina, I. G.; Noginova, L. Yu; Iosilevskiy, I. L.
2018-01-01
Impressive appearance of discontinuities in equilibrium spatial charge profiles in non-uniform Coulomb systems is under discussions in wide number of thermoelectrostatics problems. Such discontinuities are considered as peculiar micro-level manifestation of phase transitions and intrinsic macro-level non-ideality effects in local equation of state (EOS), which should be used for description of non-ideal ionic subsystem in frames of local-density (or “pseudofluid”, or “jellium” etc) approximation. Such discontinuities were discussed already by the authors for electronic subsystems. Special emphasis is made in present paper on the mentioned above non-ideality effects in non-uniform ionic subsystems, such as micro-ions profile within screening “cloud” around macro-ion in complex (dusty, colloid etc) plasmas, equilibrium charge profile in ionic traps or (and) in the neighborhood vicinity of “charged wall” etc). Multiphase EOS for simplified ionic model of classical charged hard spheres on uniformly compressible electrostatic compensating background was constructed and several illustrative examples of discussed discontinuous ionic profiles were calculated.
Alternative methods for evaluation of non-uniformity in nuclear medicine images
International Nuclear Information System (INIS)
Rasaneh, S.; Rajabi, H.; Hajizadeh, E.
2005-01-01
Non-uniformity test is the most essential in daily quality control procedures of nuclear medicine equipment's. However, the calculation of non-uniformity is hindered due to high level of noise in nuclear medicine data. Non-uniformity may be considered as a type of systematic error while noise is certainly a random error. The present methods of uniformity evaluation are not able to distinguish between systematic and random error and therefore produce incorrect results when noise is significant. In the present study, two hypothetical methods have been tested for evaluation of non-uniformity in nuclear medicine images. Materials and Methods: Using the Monte Carlo method, uniform and non-uniform flood images of different matrix sizes and different counts were generated. The uniformity of the images was calculated using the conventional method and proposed methods. The results were compared with the known non-uniformity data of simulated images. Results: It was observed that the value of integral uniformity never went below the recommended values except in small matrix size of high counts (more than 80 millions counts). The differential uniformity was quite insensitive to the degree of non-uniformity in large matrix size. Matrix size of 64*64 was only found to be suitable for the calculation of differential uniformity. It was observed that in uniform images, a small amount of non-uniformity changes the p-value of Kolmogorov-Smirnov test and noise amplitude of fast fourier transformation test significantly while the conventional methods failed to detect the nonuniformity. Conclusion: The conventional methods do not distinguish noise, which is always present in the data and occasional non-uniformity at low count density. In a uniform intact flood image, the difference between maximum and minimum pixel count (the value of integral uniformity) is much more than the recommended values for non-uniformity. After filtration of image, this difference decreases, but remains high
Ohlhorst, Craig W.; Sawyer, James Wayne; Yamaki, Y. Robert
1989-01-01
An experimental evaluation has been conducted to ascertain the the usefulness of two techniques for measuring in-plane compressive failure strength and modulus in coated and uncoated carbon-carbon composites. The techniques involved testing specimens with potted ends as well as testing them in a novel clamping fixture; specimen shape, length, gage width, and thickness were the test parameters investigated for both coated and uncoated 0/90 deg and +/-45 deg laminates. It is found that specimen shape does not have a significant effect on the measured compressive properties. The potting of specimen ends results in slightly higher measured compressive strengths than those obtained with the new clamping fixture. Comparable modulus values are obtained by both techniques.
Influence of Non-Uniform Magnetic Field on Quantum Teleportation in Heisenberg XY Model
Institute of Scientific and Technical Information of China (English)
SHAO Bin; YANG Tie-jian; ZHAO Yue-hong; ZOU Jian
2007-01-01
By considering the intrinsic decoherence, the validity of quantum teleportation of a two-qubit 1D Heisenberg XY chain in a non-uniform external magnetic field is studied. The fidelity as the measurement of a possible quantum teleportation is calculated and the effects of the non-uniform magnetic field and the intrinsic decoherence are discussed. It is found that anti-parallel magnetic field is more favorable for teleportation and the fidelity is suppressed by the intrinsic decoherence.
Compressor Performance Scaling in the Presence of Non-Uniform Flow
Hill, David Jarrod
Fuselage-embedded engines in future aircraft will see increased flow distortions due to the ingestion of airframe boundary layers. This reduces the required propulsive power compared to podded engines. Inlet flow distortions mean that localized regions of flow within the fan and first stage compressor are operating at off-design conditions. It is important to weigh the benefit of increased vehicle propulsive efficiency against the resultant reduction in engine efficiency. High computational cost has limited most past research to single distortion studies. The objective of this thesis is to extract scaling laws for transonic compressor performance in the presence of various distortion patterns and intensities. The machine studied is the NASA R67 transonic compressor. Volumetric source terms are used to model rotor and stator blade rows. The modelling approach is an innovative combination of existing flow turning and loss models, combined with a compressible flow correction. This approach allows for a steady calculation to capture distortion transfer; as a result, the computational cost is reduced by two orders of magnitude. At peak efficiency, the rotor work coefficient and isentropic efficiency are matched within 1.4% of previously published experimental results. A key finding of this thesis is that, in non-uniform flow, the state-of-the-art loss model employed is unable to capture the impact of variations in local flow coefficient, limiting the analysis of local entropy generation. New insight explains the mechanism governing the interaction between a total temperature distortion and a compressor rotor. A parametric study comprising 16 inlet distortions reveals that for total temperature distortions, upstream flow redistribution and rotor diffusion factor changes are shown to scale linearly with distortion severity. Linear diffusion factor scaling does not hold true for total pressure distortions. For combined total temperature and total pressure distortions, the
A neural algorithm for the non-uniform and adaptive sampling of biomedical data.
Mesin, Luca
2016-04-01
Body sensors are finding increasing applications in the self-monitoring for health-care and in the remote surveillance of sensitive people. The physiological data to be sampled can be non-stationary, with bursts of high amplitude and frequency content providing most information. Such data could be sampled efficiently with a non-uniform schedule that increases the sampling rate only during activity bursts. A real time and adaptive algorithm is proposed to select the sampling rate, in order to reduce the number of measured samples, but still recording the main information. The algorithm is based on a neural network which predicts the subsequent samples and their uncertainties, requiring a measurement only when the risk of the prediction is larger than a selectable threshold. Four examples of application to biomedical data are discussed: electromyogram, electrocardiogram, electroencephalogram, and body acceleration. Sampling rates are reduced under the Nyquist limit, still preserving an accurate representation of the data and of their power spectral densities (PSD). For example, sampling at 60% of the Nyquist frequency, the percentage average rectified errors in estimating the signals are on the order of 10% and the PSD is fairly represented, until the highest frequencies. The method outperforms both uniform sampling and compressive sensing applied to the same data. The discussed method allows to go beyond Nyquist limit, still preserving the information content of non-stationary biomedical signals. It could find applications in body sensor networks to lower the number of wireless communications (saving sensor power) and to reduce the occupation of memory. Copyright © 2016 Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Zorareh Hadj Mohammad
Full Text Available The paper addresses the problem of the influence of randomly distributed corrosion wastage on the collapse strength and behaviour of unstiffened/stiffened steel plates in longitudinal compression. A series of elastic-plastic large deflection finite element analyses is performed on both-sides randomly corroded steel plates and stiffened plates. The effects of general corrosion are introduced into the finite element models using a novel random thickness surface model. Buckling strength, post-buckling behaviour, ultimate strength and post-ultimate behaviour of the models are investigated as results of both-sides random corrosion.
Directory of Open Access Journals (Sweden)
Abdullah Abd Halid
2017-01-01
Full Text Available Compressed Stabilized Earth Brick (CSEB is produced by compressing a mixture of water with three main materials such as Ordinary Portland Cement (OPC, soil, and sand. It becomes popularfor its good strength, better insulation properties, and a sustainable product due to its easy production with low carbon emission and less skilled labour required. Different types of local soils usedwill produce CSEB of different physical properties in terms of its strength, durability, and water absorption rate. This study focuses on laterite soil taken from the surrounding local area in Parit Raja, Johor, and CSEB samples are produced based on prototype brick size 100×50×30 mm. The investigations are based on four different degree of compactions (i.e. 1500, 2000, 2500, and 3000 Psi and three different mix proportion ratios of cement:sand:laterite soil (i.e. 1:1:9, 1:2:8, 1:3:7. A total of 144 CSEB samples have been tested at 7 and 28 days curing periods to determine the compressive strength (BS 3921:1985 and water absorption rate (MS 76:1972. It was found that maximum compressive strength of CSEB was 14.68 N/mm2 for mixture ratio of 1:3:7 at 2500 Psi compaction. Whereas, the minimum strengthis 6.87 N/mm2 for 1:1:9mixture ratio at 1500 Psi. Meanwhile, the lowest water absorption was 12.35% for mixture ratio of 1:2:8 at 3000 Psi; while the 1:1:9 mixture ratio at 1500 Psi gave the highest rate of 16.81%. This study affirms that the sand content in the mixture and the degree of compaction would affect the value of compressive strength and water absorption of CSEB.
The Influence Of Loam Type And Cement Content On The Compressive Strength Of Rammed Earth
Directory of Open Access Journals (Sweden)
Narloch P. L.
2015-03-01
Full Text Available Currently, a worldwide dynamic rise of interest in using soil as a construction material can be observed. This trend is evident in the rapid rise of the amount of standards that deal with soil techniques. In 2012 the number of standards was larger by one third than five years prior. To create a full standardization of the rammed earth technique it is necessary to take into account the diversity of used soil and stabilizing additives. The proportion of the components, the process of element production and the research methods must also be made uniform. The article describes the results of research on the compressive strength of rammed earth samples that differed from each other with regards to the type of loam used for the mixture and the amount of the stabilizer. The stabilizer used was Portland cement CEM I 42.5R. The research and the analysis of the results were based on foreign publications, the New Zealand standard NZS 4298:1998, the American Standard NMAC14.7.4 and archival Polish Standards from the 1960’s that dealt with earth material.
Compressive strength of concrete by partial replacement of cement with metakaolin
Ganesh, Y. S. V.; Durgaiyya, P.; Shivanarayana, Ch.; Prasad, D. S. V.
2017-07-01
Metakaolin or calcined kaolin, other type of pozzolan, produced by calcination has the capability to replace silica fume as an alternative material. Supplementary cementitious materials have been widely used all over the world in concrete due to their economic and environmental benefits; hence, they have drawn much attention in recent years. Mineral admixtures such as fly ash, rice husk ash, silica fume etc. are more commonly used SCMs. They help in obtaining both higher performance and economy. Metakaolin is also one of such non - conventional material, which can be utilized beneficially in the construction industry. This paper presents the results of an experimental investigations carried out to find the suitability of metakaolin in production of concrete. In the present work, the results of a study carried out to investigate the effects of Metakaolin on compressive strength of concrete are presented. The referral concrete M30 was made using 43 grade OPC and the other mixes were prepared by replacing part of OPC with Metakaolin. The replacement levels were 5%, 10%, 15% and 20%(by weight) for Metakaolin. The various results, which indicate the effect of replacement of cement by metakalion on concrete, are presented in this paper to draw useful conclusions.
International Nuclear Information System (INIS)
Mateus, Jefferson; Saavedra, Nestor Fernando; Calderon Carrillo, Zuly; Mateus, Darwin
2007-01-01
A new way to characterize the perforated formation strength has been implemented using the indentation test. This test can be performed on irregular cuttings mounted in acrylic resins forming a disc. The test consists of applying load on each sample by means of a flat and indenter. A graph of the load applied VS penetration of the indenter is developed, and the modules of the test, denominated indentation modulus (IM) and Critical Transition Force (CTF) are obtained (Ringstad et al., 1998). Based on the success of previous studies we developed correlations between indentation and mechanical properties for some Colombian sandstone. These correlations were obtained using o set of 248 indentation tests and separate compression fasts on parallel sandstone samples from the same depth. This analysis includes Barco Formation, Mirador Formation, and Tambor Formation. For the correlations, IM-UCS and CTF-UCS, the correlation coefficient is 0.81 and 0.70 respectively. The use of the correlations and the indentation test is helpful for in-situ calibration of the geomechanical models since the indentation test can be performed in real time thus reducing costs and time associated with delayed conventional characterization
Roughness and compressive strength of FDM 3D printed specimens affected by acetone vapour treatment
Beniak, Juraj; Križan, Peter; Šooš, Ľubomír; Matúš, Miloš
2018-01-01
Rapid Prototyping technologies are the fastest growing technologies in the manufacturing of components and parts. There are many techniques which can be used with different materials and different purposes of produced part. Gradually, Rapid Prototyping systems have grown into Additive Manufacturing, because technology expansion brings faster production, improved manufactured components, and expanded palette of used materials. So now this techniques are also used for regular production of special parts, where is usual change of part design, where is necessary to produce variety of different designs and shapes. The following article deals with Fused Deposition Modelling (FDM) technology, the core of which is the manufacture models and components from thermoplastic polymers by deposition single fibres of semi-molten plastic material layer by layer. The article focuses on the results of research for testing of manufactured specimens by FDM technology. Components are modified by acetone vapour for surface smoothing. The purpose is to point out how the additional specimen treatment influence the strength properties. Presented paper shows realized experiments and measurements of compressive force on specimens and surface roughness which are influenced by acetone vapour treatment.
Directory of Open Access Journals (Sweden)
Chih-Chung Su
2017-02-01
Full Text Available We fabricated a 3D sandwich hybrid material composed of graphene and vertically aligned carbon nanotube forests (VACNTs using chemical vapor deposition. The graphene was first synthesized on Cu foil. Then it was transferred to a substrate which had a pre-deposited catalyst Fe film and a buffer film of Al2O3 for the growth of VACNTs. The VACNTs were grown underneath the graphene and lifted up the graphene. The graphene, with its edges anchored on the Al2O3, provided a constrained boundary condition for the VACNTs and hence affected the growth height and mechanical strength of the VACNTs. We prepared three groups of samples: VACNTs without graphene, VACNTs with graphene transferred once (1-Gr/VACNTs, and VACNTs with graphene transferred twice (2-Gr/VACNTs. A nano-indentation system was used to measure the reduced compressive modulus (Er and hardness (H. The Er and H of Gr/VACNTs increased with the number of transfers of the anchored graphene. The 2-Gr/VACNTs had the largest Er and H, 23.8 MPa and 912 KPa, which are 6.6 times and 5.2 times those of VACNTs without the anchored graphene, respectively. In this work, we have demonstrated a simple method to increase the mechanical properties and suppress the height of VACNTs with the anchored graphene and number of transfers.
Directory of Open Access Journals (Sweden)
Kruszka Leopold
2015-01-01
Full Text Available Specimen reinforced with glass and basalt fibers were prepared using Standard Portland cement (CEM I, 52.5 R as prescribed by EN 197-1 and standard sand, in accordance with EN 196-1. From this cementitious mixture, a reference cement mortar without fibers was first prepared. Compressive strength, modulus of elasticity, and mod of fracture were determined for all specimens. Static and dynamic properties were investigated using Instron testing machine and split Hopkinson pressure bar, respectively. Content of the glass fibers in the mortar does not influence the fracture stress at static loading conditions in a clearly observed way. Moreover at dynamic range 5% content of the fiber results in a significant drop of fracture stress. Analysis of the basalt fibers influence on the fracture stress shows that optimal content of this reinforcement is equal to 3% for both static and dynamic loading conditions. Further increase of the fiber share gives the opposite effect, i.e. drop of the fracture stress.
Kruszka, Leopold; Moćko, Wojciech; Fenu, Luigi; Cadoni, Ezio
2015-09-01
Specimen reinforced with glass and basalt fibers were prepared using Standard Portland cement (CEM I, 52.5 R as prescribed by EN 197-1) and standard sand, in accordance with EN 196-1. From this cementitious mixture, a reference cement mortar without fibers was first prepared. Compressive strength, modulus of elasticity, and mod of fracture were determined for all specimens. Static and dynamic properties were investigated using Instron testing machine and split Hopkinson pressure bar, respectively. Content of the glass fibers in the mortar does not influence the fracture stress at static loading conditions in a clearly observed way. Moreover at dynamic range 5% content of the fiber results in a significant drop of fracture stress. Analysis of the basalt fibers influence on the fracture stress shows that optimal content of this reinforcement is equal to 3% for both static and dynamic loading conditions. Further increase of the fiber share gives the opposite effect, i.e. drop of the fracture stress.
Experimental Study on Unconfined Compressive Strength of Basalt Fiber Reinforced Clay Soil
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Lei Gao
2015-01-01
Full Text Available In order to study the mechanism and effect of basalt fiber reinforced clay soil, a series of unconfined compressive strength tests conducted on clay soil reinforced with basalt fiber have been performed under the condition of optimum water content and maximum dry density. Both the content and length of basalt fiber are considered in this paper. When the effect of content is studied, the 12 mm long fibers are dispersed into clay soil at different contents of 0.05%, 0.1%, 0.15%, 0.20%, 0.25%, 0.30%, and 0.35%. When the effect of length is researched, different lengths of basalt fibers with 4 mm, 8 mm, 12 mm, and 15 mm are put into soil at the same content of 0.05%. Experimental results show that basalt fiber can effectively improve the UCS of clay soil. And the best content and length are 0.25% and 12 mm, respectively. The results also show that the basalt fiber reinforced clay soil has the “poststrong” characteristic. About the reinforcement mechanism, the fiber and soil column-net model is proposed in this paper. Based on this model and SEM images, the effect of fiber content and length is related to the change of fiber-soil column and formation of effective fiber-soil net.
Kaszynska, Maria; Skibicki, Szymon
2017-12-01
High-performance concrete (HPC) which contains increased amount of both higher grade cement and pozzolanic additives generates more hydration heat than the ordinary concrete. Prolonged periods of elevated temperature influence the rate of hydration process in result affecting the development of early-age strength and subsequent mechanical properties. The purpose of the presented research is to determine the relationship between the kinetics of the heat generation process and the compressive strength of early-age high performance concrete. All mixes were based on the Portland Cement CEM I 52.5 with between 7.5% to 15% of the cement mass replaced by the silica fume or metakaolin. Two characteristic for HPC water/binder ratios of w/b = 0.2 and w/b = 0.3 were chosen. A superplasticizer was used to maintain a 20-50 mm slump. Compressive strength was determined at 8h, 24h, 3, 7 and 28 days on 10x10x10 cm specimens that were cured in a calorimeter in a constant temperature of T = 20°C. The temperature inside the concrete was monitored continuously for 7 days. The study determined that the early-age strength (t<24h) of concrete with reactive mineral additives is lower than concrete without them. This is clearly visible for concretes with metakaolin which had the lowest compressive strength in early stages of hardening. The amount of the superplasticizer significantly influenced the early-age compressive strength of concrete. Concretes with additives reached the maximum temperature later than the concretes without them.
Non-Uniformity Correction Using Nonlinear Characteristic Performance Curves for Calibration
Lovejoy, McKenna Roberts
Infrared imaging is an expansive field with many applications. Advances in infrared technology have lead to a greater demand from both commercial and military sectors. However, a known problem with infrared imaging is its non-uniformity. This non-uniformity stems from the fact that each pixel in an infrared focal plane array has its own photoresponse. Many factors such as exposure time, temperature, and amplifier choice affect how the pixels respond to incoming illumination and thus impact image uniformity. To improve performance non-uniformity correction (NUC) techniques are applied. Standard calibration based techniques commonly use a linear model to approximate the nonlinear response. This often leaves unacceptable levels of residual non-uniformity. Calibration techniques often have to be repeated during use to continually correct the image. In this dissertation alternates to linear NUC algorithms are investigated. The goal of this dissertation is to determine and compare nonlinear non-uniformity correction algorithms. Ideally the results will provide better NUC performance resulting in less residual non-uniformity as well as reduce the need for recalibration. This dissertation will consider new approaches to nonlinear NUC such as higher order polynomials and exponentials. More specifically, a new gain equalization algorithm has been developed. The various nonlinear non-uniformity correction algorithms will be compared with common linear non-uniformity correction algorithms. Performance will be compared based on RMS errors, residual non-uniformity, and the impact quantization has on correction. Performance will be improved by identifying and replacing bad pixels prior to correction. Two bad pixel identification and replacement techniques will be investigated and compared. Performance will be presented in the form of simulation results as well as before and after images taken with short wave infrared cameras. The initial results show, using a third order
Hossain, M S; Gabr, M A; Asce, F
2009-09-01
In many situations, MSW components are processed and shredded before use in laboratory experiments using conventional soil testing apparatus. However, shredding MSW material may affect the target property to be measured. The objective of this study is to contribute to the understanding of the effect of shredding of MSW on the measured compressibility and strength properties. It is hypothesized that measured properties can be correlated to an R-value, the ratio of waste particle size to apparatus size. Results from oedometer tests, conducted on 63.5 mm, 100 mm, 200 mm diameter apparatus, indicated the dependency of the compressibility parameters on R-value. The compressibility parameters are similar for the same R-value even though the apparatus size varies. The results using same apparatus size with variable R-values indicated that shredding of MSW mainly affects initial compression. Creep and biological strain rate of the tested MSW are not significantly affected by R-value. The shear strength is affected by shredding as the light-weight reinforcing materials are shredded into smaller pieces during specimen preparation. For example, the measured friction angles are 32 degrees and 27 degrees for maximum particle sizes of 50 mm and 25 mm, respectively. The larger MSW components in the specimen provide better reinforcing contribution. This conclusion is however dependent on comparing specimen at the same level of degradation since shear strength is also a function of extent of degradation.
International Nuclear Information System (INIS)
Miyahara, Hiroshi; Yoshida, Makoto; Watanabe, Tamaki
1977-01-01
The α-ray thickness gauge is used to measure non-destructively the thicknesses of thin films, and up to the present day, a thin film with uniform thickness is only taken up as the object of α-ray thickness gauge. When the thickness is determined from the displacement between the absorption curves in the presence and absence of thin film, the absorption curve must be displaced in parallel. When many uniform particles were dispersed as sample, the shape of the absorption curve was calculated as the sum of many absorption curves corresponding to the thin films with different thicknesses. By the comparison of the calculated and measured absorption curves, the number of particles, or the mean superficial density can be determined. This means the extension of thickness measurement from uniform to non-uniform films. Furthermore, these particle models being applied to non-uniform thin film, the possibility of measuring the mean thickness and non-uniformity was discussed. As the result, if the maximum difference of the thickness was more than 0.2 mg/cm 2 , the nonuniformity was considered to distinguish by the usual equipment. In this paper, an α-ray thickness gauge using the absorption curve method was treated, but one can apply this easily to an α-ray thickness gauge using α-ray energy spectra before and after the penetration of thin film. (auth.)
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S. M. Alamgir Kabir
2015-01-01
Full Text Available The investigation concerns the use of the optimum mix proportion of two locally available pozzolanic waste materials, namely, ground granulated blast furnace slag (GGBS and palm oil fuel ash (POFA, together with metakaolin (MK as binders. In addition, another local waste material, manufactured sand (M-sand, was used as a replacement for conventional sand in the development of green geopolymer mortar. Twenty-four mortar mixtures were designed with varying binder contents and alkaline activators. The oven dry curing was also kept consistent for all the mix proportions at a temperature of 65°C for 24 hours. The highest 28-day compressive strength of about 48 MPa was obtained for the mortar containing 20% of MK, 35% of GGBS, and 45% of POFA. The increment of MK beyond 20% leads to reduction of the compressive strength. The GGBS replacement beyond 35% also reduced the compressive strength. The entire specimen achieved average 80% of the 28-day strength at the age of 3 days. The density decreased with the increase of POFA percentage. The finding of this research by using the combination of MK, GGBS, and POFA as binders to wholly replace conventional ordinary Portland cement would lead to alternate eco-friendly geopolymer matrix.
Muthusamy, K.; Zamri, N. A.; Kusbiantoro, A.; Lim, N. H. A. S.; Ariffin, M. A. Mohd
2018-04-01
Both palm oil fuel ash (POFA) and palm oil boiler stone (POBS) are by-products which has been continuously generated by local palm oil mill in large amount. Both by products is usually disposed as profitless waste and considered as nuisance to environment. The present research investigates the workability and compressive strength performance of lightweight aggregate concrete (LWAC) made of palm oil boiler stone (POBS) known as palm oil boiler stone lightweight aggregate concrete (POBS LWAC) containing various content of palm oil fuel ash. The control specimen that is POBS LWAC of grade 60 were produced using 100% OPC. Then, another 4 mixes were prepared by varying the POFA percentage from 10%, 20%, 30% and 40% by weight of cement. Fresh mixes were subjected to slump test to determine its workability before casted in form of cubes. Then, all specimens were subjected to water curing up to 28 days and then tested for its compressive strength. It was found out that utilizing of optimum amount of POFA in POBS LWAC would improve the workability and compressive strength of the concrete. However, inclusion of POFA more than optimum amount is not recommended as it will increase the water demand leading to lower workability and strength reduction.
Nonlinear Dynamics of Non-uniform Current-Vortex Sheets in Magnetohydrodynamic Flows
Matsuoka, C.; Nishihara, K.; Sano, T.
2017-04-01
A theoretical model is proposed to describe fully nonlinear dynamics of interfaces in two-dimensional MHD flows based on an idea of non-uniform current-vortex sheet. Application of vortex sheet model to MHD flows has a crucial difficulty because of non-conservative nature of magnetic tension. However, it is shown that when a magnetic field is initially parallel to an interface, the concept of vortex sheet can be extended to MHD flows (current-vortex sheet). Two-dimensional MHD flows are then described only by a one-dimensional Lagrange parameter on the sheet. It is also shown that bulk magnetic field and velocity can be calculated from their values on the sheet. The model is tested by MHD Richtmyer-Meshkov instability with sinusoidal vortex sheet strength. Two-dimensional ideal MHD simulations show that the nonlinear dynamics of a shocked interface with density stratification agrees fairly well with that for its corresponding potential flow. Numerical solutions of the model reproduce properly the results of the ideal MHD simulations, such as the roll-up of spike, exponential growth of magnetic field, and its saturation and oscillation. Nonlinear evolution of the interface is found to be determined by the Alfvén and Atwood numbers. Some of their dependence on the sheet dynamics and magnetic field amplification are discussed. It is shown by the model that the magnetic field amplification occurs locally associated with the nonlinear dynamics of the current-vortex sheet. We expect that our model can be applicable to a wide variety of MHD shear flows.
International Nuclear Information System (INIS)
Sanjuán, M.A.; Argiz, C.; Gálvez, J.C.; Reyes, E.
2018-01-01
The compressive strength, flexural strength, porosity and electrical resistivity properties of cement mortars with nano-Fe2O3 and nano-SiO2 are studied. Amorphous silica is the main component of pozzolanic materials due to its reaction with calcium hydroxide formed from calcium silicate (C3S and C2S) hydration. The pozzolanic reaction rate is not only proportional to the amount of amorphous silica but also to the surface area available for reaction. Subsequently, fine nano-Fe2O3 and nano-SiO2 particles in mortars are expected to improve mortar performance. The experimental results showed that the compressive strength of mortars with nano-Fe2O3 and nano-SiO2 particles were lower than those obtained with the reference mortar at seven and 28 days. It was shown that the nano-particles were not able to enhance mechanical strength on every occasion. The continuous microstructural progress monitored by mercury intrusion porosimetry (MIP) measurements, pore-size distribution (PSD), total porosity and critical pore diameter also confirmed such results. [es
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M. A. Sanjuán
2018-03-01
Full Text Available The compressive strength, flexural strength, porosity and electrical resistivity properties of cement mortars with nano-Fe2O3 and nano-SiO2 are studied. Amorphous silica is the main component of pozzolanic materials due to its reaction with calcium hydroxide formed from calcium silicate (C3S and C2S hydration. The pozzolanic reaction rate is not only proportional to the amount of amorphous silica but also to the surface area available for reaction. Subsequently, fine nano-Fe2O3 and nano-SiO2 particles in mortars are expected to improve mortar performance. The experimental results showed that the compressive strength of mortars with nano-Fe2O3 and nano-SiO2 particles were lower than those obtained with the reference mortar at seven and 28 days. It was shown that the nano-particles were not able to enhance mechanical strength on every occasion. The continuous microstructural progress monitored by mercury intrusion porosimetry (MIP measurements, pore-size distribution (PSD, total porosity and critical pore diameter also confirmed such results.
Directory of Open Access Journals (Sweden)
Rolando, A.
2006-09-01
Full Text Available In this paper the compression strength of a clay brickwork masonry bound with cement mortar is analyzed. The target is to obtain the characteristic compression strength of unreinforced brickwork masonry. This research try to test the validity of the analytical equations in European codes, comparing the experimental strength with the analytically obtained from the strength of its components (clay brick and cement mortar.En este artículo se analiza la resistencia a compresión de una fábrica de ladrillo cerámico, asentado con mortero de cemento.El objetivo es obtener la resistencia característica a compresión de la fábrica sin armar.La investigación comprueba la fiabilidad de las expresiones analíticas existentes en la normativa europea, comparando la resistencia obtenida experimentalmente con la obtenida analíticamente, a partir de la resistencia de sus componentes (ladrillo cerámico y mortero de cemento.
On natural frequencies of non-uniform beams modulated by finite periodic cells
International Nuclear Information System (INIS)
Xu, Yanlong; Zhou, Xiaoling; Wang, Wei; Wang, Longqi; Peng, Fujun; Li, Bin
2016-01-01
It is well known that an infinite periodic beam can support flexural wave band gaps. However, in real applications, the number of the periodic cells is always limited. If a uniform beam is replaced by a non-uniform beam with finite periodicity, the vibration changes are vital by mysterious. This paper employs the transfer matrix method (TMM) to study the natural frequencies of the non-uniform beams with modulation by finite periodic cells. The effects of the amounts, cross section ratios, and arrangement forms of the periodic cells on the natural frequencies are explored. The relationship between the natural frequencies of the non-uniform beams with finite periodicity and the band gap boundaries of the corresponding infinite periodic beam is also investigated. Numerical results and conclusions obtained here are favorable for designing beams with good vibration control ability. - Highlights: • The transfer matrix method to study the natural frequencies of the finite periodic non-uniform beams is derived. • The transfer matrix method to study the band gaps of the infinite periodic non-uniform beams is derived. • The effects of the periodic cells on the natural frequencies are explored. • The relationships of the natural frequencies and band gap boundaries are investigated.
On natural frequencies of non-uniform beams modulated by finite periodic cells
Energy Technology Data Exchange (ETDEWEB)
Xu, Yanlong, E-mail: xuyanlong@nwpu.edu.cn [School of Aeronautics, Northwestern Polytechnical University, Xi' an 710072, Shaanxi (China); Zhou, Xiaoling [Shanghai Institute of Aerospace System Engineering, Shanghai 201109 (China); Wang, Wei [School of Aeronautics, Northwestern Polytechnical University, Xi' an 710072, Shaanxi (China); Wang, Longqi [School of Civil & Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Peng, Fujun [Shanghai Institute of Aerospace System Engineering, Shanghai 201109 (China); Li, Bin [School of Aeronautics, Northwestern Polytechnical University, Xi' an 710072, Shaanxi (China)
2016-09-23
It is well known that an infinite periodic beam can support flexural wave band gaps. However, in real applications, the number of the periodic cells is always limited. If a uniform beam is replaced by a non-uniform beam with finite periodicity, the vibration changes are vital by mysterious. This paper employs the transfer matrix method (TMM) to study the natural frequencies of the non-uniform beams with modulation by finite periodic cells. The effects of the amounts, cross section ratios, and arrangement forms of the periodic cells on the natural frequencies are explored. The relationship between the natural frequencies of the non-uniform beams with finite periodicity and the band gap boundaries of the corresponding infinite periodic beam is also investigated. Numerical results and conclusions obtained here are favorable for designing beams with good vibration control ability. - Highlights: • The transfer matrix method to study the natural frequencies of the finite periodic non-uniform beams is derived. • The transfer matrix method to study the band gaps of the infinite periodic non-uniform beams is derived. • The effects of the periodic cells on the natural frequencies are explored. • The relationships of the natural frequencies and band gap boundaries are investigated.
Wibowo; Fadillah, Y.
2018-03-01
Efficiency in a construction works is a very important thing. Concrete with ease of workmanship and rapid achievement of service strength will to determine the level of efficiency. In this research, we studied the optimization of accelerator usage in achieving performance on compressive strength of concrete in function of time. The addition of variation of 0.3% - 2.3% to the weight of cement gives a positive impact of the rapid achievement of hardened concrete, however the speed of increasing of concrete strength achievement in term of time influence present increasing value of filling ability parameter of self-compacting concrete. The right composition of accelerator aligned with range of the values standard of filling ability parameters of HSSCC will be an advantage guidance for producers in the ready-mix concrete industry.
Díaz-Díaz, Floriberto; de J. Cano-Barrita, Prisciliano F.; Balcom, Bruce J.; Solís-Nájera, Sergio E.; Rodríguez, Alfredo O.
2013-01-01
In cement-based materials porosity plays an important role in determining their mechanical and transport properties. This paper describes an improved low–cost embeddable miniature NMR sensor capable of non-destructively measuring evaporable water loss and porosity refinement in low and high water-to-cement ratio cement-based materials. The sensor consists of two NdFeB magnets having their North and South poles facing each other, separated by 7 mm to allow space for a Faraday cage containing a Teflon tube and an ellipsoidal RF coil. To account for magnetic field changes due to temperature variations, and/or the presence of steel rebars, or frequency variation due to sample impedance, an external tuning circuit was employed. The sensor performance was evaluated by analyzing the transverse magnetization decay obtained with a CPMG measurement from different materials, such as a polymer phantom, fresh white and grey cement pastes with different w/c ratios and concrete with low (0.30) and high (0.6) w/c ratios. The results indicated that the sensor is capable of detecting changes in water content in fresh cement pastes and porosity refinement caused by cement hydration in hardened materials, even if they are prepared with a low w/c ratio (w/c = 0.30). The short lifetime component of the transverse relaxation rate is directly proportional to the compressive strength of concrete determined by destructive testing. The r2 (0.97) from the linear relationship observed is similar to that obtained using T2 data from a commercial Oxford Instruments 12.9 MHz spectrometer.
Directory of Open Access Journals (Sweden)
Floriberto Díaz-Díaz
2013-11-01
Full Text Available In cement-based materials porosity plays an important role in determining their mechanical and transport properties. This paper describes an improved low–cost embeddable miniature NMR sensor capable of non-destructively measuring evaporable water loss and porosity refinement in low and high water-to-cement ratio cement-based materials. The sensor consists of two NdFeB magnets having their North and South poles facing each other, separated by 7 mm to allow space for a Faraday cage containing a Teflon tube and an ellipsoidal RF coil. To account for magnetic field changes due to temperature variations, and/or the presence of steel rebars, or frequency variation due to sample impedance, an external tuning circuit was employed. The sensor performance was evaluated by analyzing the transverse magnetization decay obtained with a CPMG measurement from different materials, such as a polymer phantom, fresh white and grey cement pastes with different w/c ratios and concrete with low (0.30 and high (0.6 w/c ratios. The results indicated that the sensor is capable of detecting changes in water content in fresh cement pastes and porosity refinement caused by cement hydration in hardened materials, even if they are prepared with a low w/c ratio (w/c = 0.30. The short lifetime component of the transverse relaxation rate is directly proportional to the compressive strength of concrete determined by destructive testing. The r2 (0.97 from the linear relationship observed is similar to that obtained using T2 data from a commercial Oxford Instruments 12.9 MHz spectrometer.
International Nuclear Information System (INIS)
Koh, Kyungtaek; Kim, Dogyeum; Park, Chunjin; Ryu, Gumsung; Park, Jungjun; Lee, Janghwa
2013-01-01
Concrete undergoing early frost damage in cold weather will experience significant loss of not only strength, but also of permeability and durability. Accordingly, concrete codes like ACI-306R prescribe a minimum compressive strength and duration of curing to prevent frost damage at an early age and secure the quality of concrete. Such minimum compressive strength and duration of curing are mostly defined based on the strength development of concrete. However, concrete subjected to frost damage at early age may not show a consistent relationship between its strength and durability. Especially, since durability of concrete is of utmost importance in nuclear power plant structures, this relationship should be imperatively clarified. Therefore, this study verifies the feasibility of the minimum compressive strength specified in the codes like ACI-306R by evaluating the strength development and the durability preventing the frost damage of early age concrete for nuclear power plant. The results indicate that the value of 5 MPa specified by the concrete standards like ACI-306R as the minimum compressive strength to prevent the early frost damage is reasonable in terms of the strength development, but seems to be inappropriate in the viewpoint of the resistance to chloride ion penetration and freeze-thaw. Consequently, it is recommended to propose a minimum compressive strength preventing early frost damage in terms of not only the strength development, but also in terms of the durability to secure the quality of concrete for nuclear power plants in cold climates
Energy Technology Data Exchange (ETDEWEB)
Koh, Kyungtaek; Kim, Dogyeum; Park, Chunjin; Ryu, Gumsung; Park, Jungjun; Lee, Janghwa [Korea Institute Construction Technology, Goyang (Korea, Republic of)
2013-06-15
Concrete undergoing early frost damage in cold weather will experience significant loss of not only strength, but also of permeability and durability. Accordingly, concrete codes like ACI-306R prescribe a minimum compressive strength and duration of curing to prevent frost damage at an early age and secure the quality of concrete. Such minimum compressive strength and duration of curing are mostly defined based on the strength development of concrete. However, concrete subjected to frost damage at early age may not show a consistent relationship between its strength and durability. Especially, since durability of concrete is of utmost importance in nuclear power plant structures, this relationship should be imperatively clarified. Therefore, this study verifies the feasibility of the minimum compressive strength specified in the codes like ACI-306R by evaluating the strength development and the durability preventing the frost damage of early age concrete for nuclear power plant. The results indicate that the value of 5 MPa specified by the concrete standards like ACI-306R as the minimum compressive strength to prevent the early frost damage is reasonable in terms of the strength development, but seems to be inappropriate in the viewpoint of the resistance to chloride ion penetration and freeze-thaw. Consequently, it is recommended to propose a minimum compressive strength preventing early frost damage in terms of not only the strength development, but also in terms of the durability to secure the quality of concrete for nuclear power plants in cold climates.
An efficient shutter-less non-uniformity correction method for infrared focal plane arrays
Huang, Xiyan; Sui, Xiubao; Zhao, Yao
2017-02-01
The non-uniformity response in infrared focal plane array (IRFPA) detectors has a bad effect on images with fixed pattern noise. At present, it is common to use shutter to prevent from radiation of target and to update the parameters of non-uniformity correction in the infrared imaging system. The use of shutter causes "freezing" image. And inevitably, there exists the problems of the instability and reliability of system, power consumption, and concealment of infrared detection. In this paper, we present an efficient shutter-less non-uniformity correction (NUC) method for infrared focal plane arrays. The infrared imaging system can use the data gaining in thermostat to calculate the incident infrared radiation by shell real-timely. And the primary output of detector except the shell radiation can be corrected by the gain coefficient. This method has been tested in real infrared imaging system, reaching high correction level, reducing fixed pattern noise, adapting wide temperature range.
A poloidal non-uniformity of the collisionless parallel current in a tokamak plasma
Energy Technology Data Exchange (ETDEWEB)
Romannikov, A.; Fenzi-Bonizec, C
2005-07-01
The collisionless distortion of the ion (electron) distribution function at certain points on a magnetic surface is studied in the framework of a simple model of a large aspect ratio tokamak plasma. The flow velocity driven by this distortion is calculated. The possibility of an additional non-uniform collisionless parallel current density on a magnetic surface, other than the known neo-classical non-uniformity is shown. The difference between the parallel current density on the low and high field side of a magnetic surface is close to the neoclassical bootstrap current density. The first Tore-Supra experimental test indicates the possibility of the poloidal non-uniformity of the parallel current density. (authors)
Directory of Open Access Journals (Sweden)
Jaber Ali
2018-01-01
Full Text Available This paper describes the relationship between splitting tensile strength and compressive strength of self-consolidating concrete using data collected from laboratory specimens tested at standard conditions. The results were then compared with some expressions published in international literature. The investigated variables included: type of cement, percentage of nanosilica and percentage of microsilica as a cement replacement by weight. In spite of concrete not being designed to resist direct tension the knowledge of tensile strength is needed to estimate the cracking load. In the absence of test results an estimate of the tensile strength may be obtained by using the relationship proposed. The verification of the proposed formula based on experimental data was estimated by means of the integral absolute error (IAE. The output of this study has provided a better understanding of the correlation between splitting and compressive strengths of SCCs and the effect of some related variables on the resultant behavior, which has therefore, helped to generate new expression with better accuracy.
Lattimer, C R; Kalodiki, E; Azzam, M; Geroulakos, G
2016-07-01
To test the in vivo haemodynamic performance of graduated elastic compression (GEC) stockings using air-plethysmography (APG) in healthy volunteers (controls) and patients with varicose veins (VVs), post-thrombotic syndrome (PTS), or lymphoedema. Responsiveness data were used to determine which group benefited the most from GEC. There were 12 patients per group compared using no compression, knee-length Class 1 (18-21 mmHg) compression, and Class 2 (23-32 mmHg) compression. Stocking/leg interface pressures (mmHg) were measured supine in two places using an air-sensor transducer. Stocking performance parameters, investigated before and after GEC, included the standard APG tests (working venous volume [wVV], venous filling index [VFI], venous drainage index [VDI], ejection fraction [EF]) and the occlusion plethysmography tests (incremental pressure causing the maximal increase in calf volume [IPMIV], outflow fraction [OF]). Results were expressed as median and interquartile range. Significant graduated compression was achieved in all four groups with higher interface pressures at the ankle. Only the VVs patients had a significant reduction in their wVV (without: 133 [109-146] vs. class1: 93 [74-113] mL) and the VFI (without: 4.6 [3-7.1] vs. class1: 3.1 [1.9-5] mL/s), both at p <.05. The IPMIV improved significantly in all groups except in the PTS group (p <.05). The OF improved only in the controls (without: 43 [38-51] vs. class1: 50 [48-53] %) and the VVs patients (without: 47 [39-58] vs. class1: 56 [50-64] %), both at p <.05. There were no significant differences in the VDI or the EF with GEC. Compression dose-response relationships were not observed. Patients with varicose veins improved the most, whereas those with PTS improved the least. Performance seemed to depend more on disease pathophysiology than compression strength. However, the lack of responsiveness to compression strength may be related to the low external pressures used. Stocking performance tests
Photocathode non-uniformity contribution to the energy resolution of scintillators
International Nuclear Information System (INIS)
Mottaghian, M.; Koohi-Fayegh, R.; Ghal-Eh, N.; Etaati, G. R.
2010-01-01
This paper introduces the basics of the light transport simulation in scintillators and the wavelength-dependencies in the process. The non-uniformity measurement of the photocathode surface is undertaken, showing that for the photocathode used in this study the quantum efficiency falls to about 4% of its maximum value, especially in areas far from the centre. The wavelength-and position-dependent quantum efficiency is implemented in the Monte Carlo light transport code, showing that, the contribution of the photocathode non-uniformity to the energy resolution is estimated to be around 18%, when all position-and wavelength-dependencies are included. (authors)
Effects of non-uniformities on electrical conduction in weakly ionized plasmas
International Nuclear Information System (INIS)
Numano, M.; Murakami, Y.; Nitta, T.
1989-01-01
The effect of non-uniformities on the flow of electric current in weakly ionized plasmas is investigated by taking into account the ion slip as well as the Hall current. An Ohm's law for a non-uniform plasma is derived, from which the formula previously obtained by Numano, i.e. an extension of Rosa's equation, is obtainable as a special case. Making use of this new Ohm's law, the effective electrical conductivity and the effective Hall parameter are determined for isotropically turbulent plasmas. It is found that when the ion-slip effect is absent they are in good agreement with the results obtained previously. (author)
The Pierce diode with an external circuit: II, Non-uniform equilibria
International Nuclear Information System (INIS)
Lawson, W.S.
1987-01-01
The non-uniform (non-linear) equilibria of the classical (short circuit) Pierce diode and the extended (series RLC external circuit) Pierce diode are described theoretically, and explored via computer simulation. It is found that most equilibria are correctly predicted by theory, but that the continuous set of equilibria of the classical Pierce diode at α = 2π are not observed. The stability characteristics of the non-uniform equilibria are also worked out, and are consistent with the simulations. 8 refs., 22 figs., 3 tabs
Additive non-uniform random sampling in superimposed fiber Bragg grating strain gauge
International Nuclear Information System (INIS)
Ma, Y C; Liu, H Y; Yan, S B; Li, J M; Tang, J; Yang, Y H; Yang, M W
2013-01-01
This paper demonstrates an additive non-uniform random sampling and interrogation method for dynamic and/or static strain gauge using a reflection spectrum from two superimposed fiber Bragg gratings (FBGs). The superimposed FBGs are designed to generate non-equidistant space of a sensing pulse train in the time domain during dynamic strain gauge. By combining centroid finding with smooth filtering methods, both the interrogation speed and accuracy are improved. A 1.9 kHz dynamic strain is measured by generating an additive non-uniform randomly distributed 2 kHz optical sensing pulse train from a mean 500 Hz triangular periodically changing scanning frequency. (paper)
Additive non-uniform random sampling in superimposed fiber Bragg grating strain gauge
Ma, Y. C.; Liu, H. Y.; Yan, S. B.; Yang, Y. H.; Yang, M. W.; Li, J. M.; Tang, J.
2013-05-01
This paper demonstrates an additive non-uniform random sampling and interrogation method for dynamic and/or static strain gauge using a reflection spectrum from two superimposed fiber Bragg gratings (FBGs). The superimposed FBGs are designed to generate non-equidistant space of a sensing pulse train in the time domain during dynamic strain gauge. By combining centroid finding with smooth filtering methods, both the interrogation speed and accuracy are improved. A 1.9 kHz dynamic strain is measured by generating an additive non-uniform randomly distributed 2 kHz optical sensing pulse train from a mean 500 Hz triangular periodically changing scanning frequency.
Directory of Open Access Journals (Sweden)
FAREED AHMED MEMON
2010-10-01
Full Text Available This research study comprises of concrete cubes made with Ordinary Portland Cement and with different configurations of fly ash by replacing cement and fine aggregate. To achieve the aim of this study, total 81 concrete cubes were cast. Among 81 cubes, 9 cubes were made with normal concrete, 36 cubes were made by replacing 25%, 50%, 75% and 100% of fine aggregate with fly ash and 36 cubes were made by replacing 10%, 25%, 50%, and 75% of cement with fly ash. The cubes were 6\\" x 6\\" in cross-section, and the mix design was aimed for 5000 psi. After proper curing of all 81 cubes, they were tested at 3, 7 and 28 days curing age. The cubes were tested in Forney Universal Testing Machine. By analyzing the test results of all the concrete cubes, the following main findings have been drawn. The compressive strength of concrete cubes made by replacing 100 % fine aggregate by fly ash was higher than the concrete cubes made with Ordinary Portland Cement at all 3, 7 and 28 days curing ages. On the other hand, the compressive strength of concrete cubes made by replacing 10 % and 25 % cement by fly ash was slightly lower than the concrete cubes made with Ordinary Portland Cement at all curing ages, whereas, the compressive strength of concrete cubes made by replacing 50 % and 75 % of cement by fly ash were quite lower than the concrete cubes made with Ordinary Portland Cement at all curing ages.
Raut, Anjana; Rao, Polsani Laxman; Vikas, B V J; Ravindranath, T; Paradkar, Archana; Malakondaiah, G
2013-01-01
Acrylic resins have been in the center stage of Prosthodontics for more than half a century. The flexural fatigue failure of denture base materials is the primary mode of clinical failure. Hence there is a need for superior physical and mechanical properties. This in vitro study compared the transverse strength of specimens of thermopressed injection-molded and conventional compression-molded polymethylmethacrylate polymers and examined the morphology and microstructure of fractured acrylic specimens. The following denture base resins were examined: Brecrystal (Thermopressed injection-molded, modified polymethylmethacrylate) and Pyrax (compression molded, control group). Specimens of each material were tested according to the American Society for Testing and Materials standard D790-03 for flexural strength testing of reinforced plastics and subsequently examined under SEM. The data was analyzed with Student unpaired t test. Flexural strength of Brecrystal (82.08 ± 1.27 MPa) was significantly higher than Pyrax (72.76 ± 0.97 MPa). The tested denture base materials fulfilled the requirements regarding flexural strength (>65 MPa). The scanning electron microscopy image of Brecrystal revealed a ductile fracture with crazing. The fracture pattern of control group specimens exhibited poorly defined crystallographic planes with a high degree of disorganization. Flexural strength of Brecrystal was significantly higher than the control group. Brecrystal showed a higher mean transverse strength value of 82.08 ± 1.27 MPa and a more homogenous pattern at microscopic level. Based on flexural strength properties and handling characteristics, Brecrystal may prove to be an useful alternative to conventional denture base resins.
Directory of Open Access Journals (Sweden)
Anjana Raut
2013-01-01
Full Text Available Statement of Problem: Acrylic resins have been in the center stage of Prosthodontics for more than half a century. The flexural fatigue failure of denture base materials is the primary mode of clinical failure. Hence there is a need for superior physical and mechanical properties. Purpose: This in vitro study compared the transverse strength of specimens of thermopressed injection-molded and conventional compression-molded polymethylmethacrylate polymers and examined the morphology and microstructure of fractured acrylic specimens. Materials and Methods: The following denture base resins were examined: Brecrystal (Thermopressed injection-molded, modified polymethylmethacrylate and Pyrax (compression molded, control group. Specimens of each material were tested according to the American Society for Testing and Materials standard D790-03 for flexural strength testing of reinforced plastics and subsequently examined under SEM. The data was analyzed with Student unpaired t test. Results: Flexural strength of Brecrystal (82.08 ± 1.27 MPa was significantly higher than Pyrax (72.76 ± 0.97 MPa. The tested denture base materials fulfilled the requirements regarding flexural strength (>65 MPa. The scanning electron microscopy image of Brecrystal revealed a ductile fracture with crazing. The fracture pattern of control group specimens exhibited poorly defined crystallographic planes with a high degree of disorganization. Conclusion: Flexural strength of Brecrystal was significantly higher than the control group. Brecrystal showed a higher mean transverse strength value of 82.08 ± 1.27 MPa and a more homogenous pattern at microscopic level. Based on flexural strength properties and handling characteristics, Brecrystal may prove to be an useful alternative to conventional denture base resins.
Zhang, Lixin; Zhang, Wencong; Cao, Biao; Chen, Wenzhen; Duan, Junpeng; Cui, Guorong
2017-10-26
The ZK61 alloy rods with different grain sizes and crystallographic texture were successfully fabricated by cyclic extrusion and compression (CEC). Their room-temperature tension & compression yield strength displayed a significant dependence on grain size and texture, essentially attributed to {10-12} twinning. The texture variations were characterized by the angle θ between the c-axis of the grain and the extrusion direction (ED) during the process. The contour map of room-temperature yield strength as a function of grain size and the angle θ was obtained. It showed that both the tension yield strength and the compression yield strength of ZK61 alloy were fully consistent with the Hall-Patch relationship at a certain texture, but the change trends of the tension yield strength and the compression yield strength were completely opposite at the same grain size while texture altered. The friction stresses of different deformation modes calculated based on the texture confirmed the tension yield strength of the CECed ZK61 alloy rods, which was determined by both the basal slip and the tension twinning slip during the tension deformation at room temperature, while the compression yield strength was mainly determined by the basal slip during the compression deformation.
Energy Technology Data Exchange (ETDEWEB)
Pinkerton, Gary Wayne [Univ. of Illinois, Urbana-Champaign, IL (United States)
1993-01-01
The purpose of this study is to find aluminum alloys that are effective for use as wire vacuum seals in the 800MeV particle accelerator located at the Louis Anderson Meson Physics Facility (LAMPF) in Los Alamos, NM. Three alloys, Al 1100, Al 3003, and Al 6061, are investigated under uniaxial compression to determine stresses for a given height reduction from 0 to 70 percent, and to find plastic flow and surface interaction effects. Right-circular cylindrical specimens are compressed on-end (cylindrically) and radially (for modeling as compressed wire). Aluminum 1100 and 3003 alloys are compared for length to diameter ratios of 1 and 2 for both compression types, and are then compared to results of radial compression of annealed small diameter Al 1100 wire currently used at LAMPE. The specimens are also compressed between three different platen surfaces, polished steel, etched steel, and aluminum 6061-T6, to determine effects of friction. The Al 3003 alloy exhibits 20 to 25% lower stresses at all height reductions than Al 1100 for both cylindrical and radial compression.
International Nuclear Information System (INIS)
Pinkerton, G.W.
1993-01-01
The purpose of this study is to find aluminum alloys that are effective for use as wire vacuum seals in the 800MeV particle accelerator located at the Louis Anderson Meson Physics Facility (LAMPF) in Los Alamos, NM. Three alloys, Al 1100, Al 3003, and Al 6061, are investigated under uniaxial compression to determine stresses for a given height reduction from 0 to 70 percent, and to find plastic flow and surface interaction effects. Right-circular cylindrical specimens are compressed on-end (cylindrically) and radially (for modeling as compressed wire). Aluminum 1100 and 3003 alloys are compared for length to diameter ratios of 1 and 2 for both compression types, and are then compared to results of radial compression of annealed small diameter Al 1100 wire currently used at LAMPE. The specimens are also compressed between three different platen surfaces, polished steel, etched steel, and aluminum 6061-T6, to determine effects of friction. The Al 3003 alloy exhibits 20 to 25% lower stresses at all height reductions than Al 1100 for both cylindrical and radial compression
Acoustic holography for piston sound radiation with non-uniform velocity profiles
Aarts, R.M.; Janssen, A.J.E.M.
2010-01-01
The theory of orthogonal (Zernike) expansions of functions on a disk, as used in the diffraction theory of optical aberrations, is applied to obtain (semi-) analytical results for the radiation of sound due to a non-uniformly moving, baffled, circular piston. For this particular case, a scheme for
Deep convolutional neural networks for dense non-uniform motion deblurring
CSIR Research Space (South Africa)
Cronje, J
2015-11-01
Full Text Available to form a dense non-uniform motion estimation map. Furthermore, a second CNN is trained to perform deblurring given a blurry image patch and the estimated motion vector. Combining the two trained networks result in a deep learning approach that can enhance...
Pondermotive absorption of a short intense laser pulse in a non-uniform plasma
Energy Technology Data Exchange (ETDEWEB)
Andreev, A A; Platonov, K Yu [Inst. for Laser Physics, SC ` Vavilov State Optical Inst.` 12, Birzhevaya line, St Petersburg (Russian Federation); Tanaka, K A
1998-03-01
An analytical description of the pondermotive absorption mechanism at a short high intense laser pulse interaction with a strong inhomogeneous plasma is presented. The optimal conditions for the maximum of resonance absorption of laser pulse interaction with non-uniform plasma at normal incidence are founded. (author)
Dynamic behaviour of non-uniform Bernoulli-Euler beams subjected ...
African Journals Online (AJOL)
This paper investigates the dynamics behaviour of non-uniform Bernoulli-Euler beams subjected to concentrated loads ravelling at variable velocities. The solution technique is based on the Generalized Galerkin Method and the use of the generating function of the Bessel function type. The results show that, for all the ...
On The Dynamic Analysis of Non-Uniform Beams Under Uniformly ...
African Journals Online (AJOL)
... the non-uniform continuous beam was replaced by a non-continuous (discrete) system made up of beam elements. The modified elemental and overall stiffness, and mass matrices, the elemental and overall centripetal acceleration matrices as well as the load vector were derived. Next, the Newmark's direct integration ...
Analysis of single blow effectiveness in non-uniform parallel plate regenerators
DEFF Research Database (Denmark)
Jensen, Jesper Buch; Bahl, Christian Robert Haffenden; Engelbrecht, Kurt
2011-01-01
Non-uniform distributions of plate spacings in parallel plate regenerators have been found to induce loss of performance. In this paper, it has been investigated how variations of three geometric parameters (the aspect ratio, the porosity, and the standard deviation of the plate spacing) affects...
A DSP-based neural network non-uniformity correction algorithm for IRFPA
Liu, Chong-liang; Jin, Wei-qi; Cao, Yang; Liu, Xiu
2009-07-01
An effective neural network non-uniformity correction (NUC) algorithm based on DSP is proposed in this paper. The non-uniform response in infrared focal plane array (IRFPA) detectors produces corrupted images with a fixed-pattern noise(FPN).We introduced and analyzed the artificial neural network scene-based non-uniformity correction (SBNUC) algorithm. A design of DSP-based NUC development platform for IRFPA is described. The DSP hardware platform designed is of low power consumption, with 32-bit fixed point DSP TMS320DM643 as the kernel processor. The dependability and expansibility of the software have been improved by DSP/BIOS real-time operating system and Reference Framework 5. In order to realize real-time performance, the calibration parameters update is set at a lower task priority then video input and output in DSP/BIOS. In this way, calibration parameters updating will not affect video streams. The work flow of the system and the strategy of real-time realization are introduced. Experiments on real infrared imaging sequences demonstrate that this algorithm requires only a few frames to obtain high quality corrections. It is computationally efficient and suitable for all kinds of non-uniformity.
Low-frequency electrostatic dust-modes in a non-uniform
Indian Academy of Sciences (India)
A self-consistent and general description of obliquely propagating low-frequency electrostatic dust-modes in a non-uniform magnetized dusty plasma system has been presented. A number of different situations, which correspond to different low-frequency electrostatic dust-modes, namely, dust-acoustic mode, dust-drift ...
Sharp lower bounds on the extractable randomness from non-uniform sources
Skoric, B.; Obi, C.; Verbitskiy, E.A.; Schoenmakers, B.
2011-01-01
Extraction of uniform randomness from (noisy) non-uniform sources is an important primitive in many security applications, e.g. (pseudo-)random number generators, privacy-preserving biometrics, and key storage based on Physical Unclonable Functions. Generic extraction methods exist, using universal
Directory of Open Access Journals (Sweden)
Stefan Leger
2017-10-01
Conclusion: The proposed PCM algorithm led to a significantly improved image quality compared to the originally acquired images, suggesting that it is applicable to the correction of MRI data. Thus it may help to reduce intensity non-uniformity which is an important step for advanced image analysis.
Planned studies of charge collection in non-uniformly irradiated Si and GaAs detectors
International Nuclear Information System (INIS)
Rosenfeld, A.; Reinhard, M.; Carolan, M.; Kaplan, G.; Lerch, M.; Alexiev, D.
1995-01-01
The aim of this project is to study the time and amplitude characteristics of silicon ion-implanted detectors non-uniformly irradiated with fast neutrons in order to predict their radiation behaviour in the LHC and space. It is expected in such detectors increases of the charge deficit due to trapping by large scale traps and transient time increases due to the reduction of the mobility. The theoretical model will be modified to describe the charge kinetics in the electrical field of the detector created by a non uniform space charge distribution. Experimental confirmation techniques are needed to develop non uniform predictable damage of silicon detectors using fast neutron sources (accelerators, reactors) and to study peculiarities of the charge transport in different parts of the detector. In parallel to experimental research will be started the theoretical development of the charge transport model for non-uniform distribution of space charge in the depletion layer (Neff). The model will include the linear distribution of Neff(y) along the detector as well as the change of sign of Neff (conversion from n to p type of silicon) inside the detector
An improved non-uniformity correction algorithm and its GPU parallel implementation
Cheng, Kuanhong; Zhou, Huixin; Qin, Hanlin; Zhao, Dong; Qian, Kun; Rong, Shenghui
2018-05-01
The performance of SLP-THP based non-uniformity correction algorithm is seriously affected by the result of SLP filter, which always leads to image blurring and ghosting artifacts. To address this problem, an improved SLP-THP based non-uniformity correction method with curvature constraint was proposed. Here we put forward a new way to estimate spatial low frequency component. First, the details and contours of input image were obtained respectively by minimizing local Gaussian curvature and mean curvature of image surface. Then, the guided filter was utilized to combine these two parts together to get the estimate of spatial low frequency component. Finally, we brought this SLP component into SLP-THP method to achieve non-uniformity correction. The performance of proposed algorithm was verified by several real and simulated infrared image sequences. The experimental results indicated that the proposed algorithm can reduce the non-uniformity without detail losing. After that, a GPU based parallel implementation that runs 150 times faster than CPU was presented, which showed the proposed algorithm has great potential for real time application.
Kenjeres, S.
2008-01-01
The paper reports on a comprehensive mathematical model for simulations of blood flow under the presence of strong non-uniform magnetic fields. The model consists of a set of Navier–Stokes equations accounting for the Lorentz and magnetisation forces, and a simplified set of Maxwell’s equations
Effect of disjoining pressure in a thin film equation with non-uniform forcing
MOULTON, D. E.; LEGA, J.
2013-01-01
We explore the effect of disjoining pressure on a thin film equation in the presence of a non-uniform body force, motivated by a model describing the reverse draining of a magnetic film. To this end, we use a combination of numerical investigations
Non-uniform approximations for sums of discrete m-dependent random variables
Vellaisamy, P.; Cekanavicius, V.
2013-01-01
Non-uniform estimates are obtained for Poisson, compound Poisson, translated Poisson, negative binomial and binomial approximations to sums of of m-dependent integer-valued random variables. Estimates for Wasserstein metric also follow easily from our results. The results are then exemplified by the approximation of Poisson binomial distribution, 2-runs and $m$-dependent $(k_1,k_2)$-events.
DEFF Research Database (Denmark)
Si, Haiqing; Shen, Wen Zhong; Zhu, Wei Jun
2013-01-01
Acoustic propagation in the presence of a non-uniform mean flow is studied numerically by using two different acoustic propagating models, which solve linearized Euler equations (LEE) and acoustic perturbation equations (APE). As noise induced by turbulent flows often propagates from near field t...
Modelling non-uniform strain distributions in aerospace composites using fibre Bragg gratings
Rajabzadehdizaji, Aydin; Groves, R.M.; Hendriks, R.C.; Heusdens, R.; Chung, Y.; Jin, W.; Lee, B.; Canning, J.; Nakamura, K.; Yuan, L.
2017-01-01
In this paper the behaviour of fibre Bragg grating (FBG) sensors under non-uniform strain distributions was analysed. Using the fundamental matrix approach, the length of the FBG sensor was discretised, with each segment undergoing different strain values. FBG sensors that are embedded inside
Modeling of parallel-plate regenerators with non-uniform plate distributions
DEFF Research Database (Denmark)
Jensen, Jesper Buch; Engelbrecht, Kurt; Bahl, Christian Robert Haffenden
2010-01-01
plate spacing distributions are presented in order to understand the impact of spacing non-uniformity. Simulations of more realistic distributions where the plate spacings follow normal distributions are then discussed in order to describe the deviation of the performance of a regenerator relative...
Below-threshold harmonic generation from strong non-uniform fields
Yavuz, I.
2017-10-01
Strong-field photoemission below the ionization threshold is a rich/complex region where atomic emission and harmonic generation may coexist. We studied the mechanism of below-threshold harmonics (BTH) from spatially non-uniform local fields near the metallic nanostructures. Discrete harmonics are generated due to the broken inversion symmetry, suggesting enriched coherent emission in the vuv frequency range. Through the numerical solution of the time-dependent Schrödinger equation, we investigate wavelength and intensity dependence of BTH. Wavelength dependence identifies counter-regular resonances; individual contributions from the multi-photon emission and channel-closing effects due to quantum path interferences. In order to understand the underlying mechanism of BTH, we devised a generalized semi-classical model, including the influence of Coulomb and non-uniform field interactions. As in uniform fields, Coulomb potential in non-uniform fields is the determinant of BTH; we observed that the generation of BTH are due to returning trajectories with negative energies. Due to large distance effectiveness of the non-uniformity, only long trajectories are noticeably affected.
Long-range weight functions in fundamental measure theory of the non-uniform hard-sphere fluid
International Nuclear Information System (INIS)
Hansen-Goos, Hendrik
2016-01-01
We introduce long-range weight functions to the framework of fundamental measure theory (FMT) of the non-uniform, single-component hard-sphere fluid. While the range of the usual weight functions is equal to the hard-sphere radius R , the modified weight functions have range 3 R . Based on the augmented FMT, we calculate the radial distribution function g (r) up to second order in the density within Percus’ test particle theory. Consistency of the compressibility and virial routes on this level allows us to determine the free parameter γ of the theory. As a side result, we obtain a value for the fourth virial coefficient B 4 which deviates by only 0.01% from the exact result. The augmented FMT is tested for the dense fluid by comparing results for g (r) calculated via the test particle route to existing results from molecular dynamics simulations. The agreement at large distances (r > 6 R) is significantly improved when the FMT with long-range weight functions is used. In order to improve agreement close to contact (r = 2 R) we construct a free energy which is based on the accurate Carnahan–Starling equation of state, rather than the Percus–Yevick compressibility equation underlying standard FMT. (paper)
International Nuclear Information System (INIS)
Shen Pei; Zhang Wanrong; Huang Lu; Jin Dongyue; Xie Hongyun
2011-01-01
An improved inductor layout with non-uniform metal width and non-uniform spacing is proposed to increase the quality factor (Q factor). For this inductor layout, from outer coil to inner coil, the metal width is reduced by an arithmetic-progression step, while the metal spacing is increased by a geometric-progression step. An improved layout with variable width and changed spacing is of benefit to the Q factor of RF spiral inductor improvement (approximately 42.86%), mainly due to the suppression of eddy-current loss by weakening the current crowding effect in the center of the spiral inductor. In order to increase the Q factor further, for the novel inductor, a patterned ground shield is used with optimized layout together. The results indicate that, in the range of 0.5 to 16 GHz, the Q factor of the novel inductor is at an optimum, which improves by 67% more than conventional inductors with uniform geometry dimensions (equal width and equal spacing), is enhanced by nearly 23% more than a PGS inductor with uniform geometry dimensions, and improves by almost 20% more than an inductor with an improved layout. (semiconductor devices)
Olivia, Monita; Ismeddiyanto, Wibisono, Gunawan; Sitompul, Iskandar R.
2017-09-01
Construction in peatland has faced scarce water sources for mixing and curing concrete. It is known that peat water has high organic content and low pH that can be harmful to concrete in the environment. In some remote areas in Riau Province, contractors used peat water directly without sufficient treatments to comply with SKSNI requirements of concrete mixing water. This paper presents a study of compressive strength, porosity and sorptivity of Ordinary Portland Cement (OPC) and blended OPC-Palm Oil Fuel Ash (OPC-POFA) concrete. The specimens were mixed using natural water and peat water, then some of them were cured in fresh water and peat water. Six mixtures were investigated using a variation of cement, mixing water and curing water. Tap water is used as control mixing and curing water for all specimens. The compressive strength, porosity and sorptivity were calculated at seven and 28 days. Results indicate that the use of peat water will cause low compressive strength, high porosity and sorptivity for both OPC and OPC-POFA concrete. Using peat water and curing the specimens in tap water could improve the early strength, porosity and sorptivity of OPC concrete; however, it has an adverse effect on OPC-POFA specimens. The properties of early age concrete of both types (OPC and OPC-POFA) using peat water were as good as those with tap water. Therefore, it is suggested that peat water should be considered as mixing and curing water for concrete where tap water resources are scarce. Investigation of its long-term properties, as well as extending the observed age of concrete is recommended before any use of peat water.
LENUS (Irish Health Repository)
Dowling, Adam H
2011-06-01
The aim was to investigate the influence of number average molecular weight and concentration of the poly(acrylic) acid (PAA) liquid constituent of a GI restorative on the compressive fracture strength (σ) and modulus (E).
2015-12-01
ARL-SR-0347 ● DEC 2015 US Army Research Laboratory An Investigation into Conversion from Non-Uniform Rational B-Spline Boundary...US Army Research Laboratory An Investigation into Conversion from Non-Uniform Rational B-Spline Boundary Representation Geometry to...from Non-Uniform Rational B-Spline Boundary Representation Geometry to Constructive Solid Geometry 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c
Directory of Open Access Journals (Sweden)
Jisong Zhang
2017-01-01
Full Text Available Ultra-high performance concrete (UHPC has superior mechanical properties and durability to normal strength concrete. However, the high amount of cement, high environmental impact, and initial cost are regarded as disadvantages, restricting its wider application. Incorporation of supplementary cementitious materials (SCMs in UHPC is an effective way to reduce the amount of cement needed while contributing to the sustainability and cost. This paper investigates the mechanical properties and microstructure of UHPC containing fly ash (FA and silica fume (SF with the aim of contributing to this issue. The results indicate that, on the basis of 30% FA replacement, the incorporation of 10% and 20% SF showed equivalent or higher mechanical properties compared to the reference samples. The microstructure and pore volume of the UHPCs were also examined. Furthermore, to minimise the experimental workload of future studies, a prediction model is developed to predict the compressive strength of the UHPC using artificial neural networks (ANNs. The results indicate that the developed ANN model has high accuracy and can be used for the prediction of the compressive strength of UHPC with these SCMs.
Muthusamy, K.; Mohamad Hafizuddin, R.; Mat Yahaya, F.; Sulaiman, M. A.; Syed Mohsin, S. M.; Tukimat, N. N.; Omar, R.; Chin, S. C.
2018-04-01
Concerns regarding the negative impact towards environment due to the increasing use of natural sand in construction industry and dumping of industrial solid wastes namely coal bottom ash (CBA) and oil palm shell (OPS) has resulted in the development of environmental friendly lightweight concrete. The present study investigates the effect of coal bottom ash as partial fine aggregate replacement towards workability and compressive strength of oil palm shell lightweight aggregate concrete (OPS LWAC). The fresh and mechanical properties of this concrete containing various percentage of coal bottom ash as partial fine aggregate replacement were investigated. The result was compared to OPS LWAC with 100 % sand as a control specimen. The concrete workability investigated by conducting slump test. All specimens were cast in form of cubes and water cured until the testing age. The compressive strength test was carried out at 7 and 28 days. The finding shows that integration of coal bottom ash at suitable proportion enhances the strength of oil palm shell lightweight aggregate concrete.
Directory of Open Access Journals (Sweden)
Saidan Motasem N.
2015-01-01
Full Text Available This paper evaluates the effect of addition of precipitated lignin, from spent pulping black liquor, to a wet single-ply linerboard handsheet followed by hot-pressing at different temperatures, on the improvement of its compressive strength. Linerboard handsheets for testing the effect of lignin addition were prepared so that the lignin-modified sheets would have the same basis weights as the control handsheets. Both the commercial and the black liquor lignin were added as a powder to wet handsheets after couching from the handsheet mold. The experiments and testing of the physical and strength properties of dried handsheets were conducted according to TAPPI test methods. The results revealed that the addition of the recovered lignin (at pH of 2 to the wet handsheet followed by hot-pressing at 150°C increased the compressive strength of linerboard handsheets by 10% to 20% above that for handsheets made without the addition of lignin. The same results were achieved using purchased lignin. However, with a 16% addition to linerboard, purchased lignin would be too expensive. These results indicate that inclusion of kraft lignin in linerboard sheets could be proved as an attractive option to reduce linerboard basis weight.
International Nuclear Information System (INIS)
Falade, F.
2013-01-01
In this study, structural properties of foamed aerated concrete with and without pulverized bone were investigated. These properties are workability, plastic and testing densities, compressive strength, and tensile strength at the design density of 1600kg/m/sub 3/. The tensile strength was evaluated by subjecting 150 x 150 x750mm unreinforced foamed concrete beams to flexural test and 150x300mm cylinder specimens were subjected to splitting test. 150mm cube specimens were used for the determination of both the compressive strength and the testing density of the foamed aerated concrete. The plastic density was investigated using a container of known volume, and its workability determined using the slump test. The pulverized bone content was varied from 0 to 20% at interval of 5%. The specimens without the pulverized bone served as the control. At the designed density of 1600 kg/m/sub 3/, the results for the control specimens at 28-day curing age are 15.43 and 13.89N/mm/sub 2/ for air-and water-cured specimens respectively. The modulus of rupture and splitting tensile strength are 2.53 and 1.63N/mm/sub 2/ respectively. The results for specimens with pulverized bone did not differ significantly from the specimens without pulverized bone. From the results of this investigation, it can be concluded that foamed aerated concrete used for this study has potential for structural applications. Also pulverized bone can be used to reduce (partially replace) the quantity of cement used in aerated concrete production; thus ridding our environment of potentially harmful wastes, as well as reduce the consumption of non-renewable resources. (author)
Directory of Open Access Journals (Sweden)
Wachilakorn Sanawung
2017-01-01
Full Text Available This research studies the effects of W/B ratios and palm oil fuel ash (POFA on compressive strength, water permeability, and chloride resistance of concrete. POFA was ground until the particles retained on sieve number 325 were less than 5% by weight. POFA was used to partially replace OPC at rates of 15, 25, and 35% by weight of binder. The water to binder (W/B ratios of concrete were 0.40 and 0.50. The compressive strength, water permeability, and chloride resistance of concrete were investigated up to 90 days. The results showed that POFA concrete with W/B ratio of 0.40 had the compressive strengths ranging from 45.8 to 55.9 MPa or 82–94% of OPC concrete at 90 days, while POFA concrete with W/B ratio of 0.50 had the compressive strengths of 33.9–41.9 MPa or 81–94% of OPC concrete. Furthermore, the compressive strength of concrete incorporation of ground POFA at 15% was the same as OPC concrete. The water permeability coefficient and the chloride ion penetration of POFA concrete were lower than OPC concrete when both types of concrete had the same compressive strengths. The findings also indicated that water permeability and chloride ion penetration of POFA concrete were significantly reduced compared to OPC concrete.
Persson, Ann-Sofie; Alderborn, Göran
2018-04-01
The objective was to present a hybrid approach to predict the strength-pressure relationship (SPR) of tablets using common compression parameters and a single measurement of tablet tensile strength. Experimental SPR were derived for six pharmaceutical powders with brittle and ductile properties and compared to predicted SPR based on a three-stage approach. The prediction was based on the Kawakita b -1 parameter and the in-die Heckel yield stress, an estimate of maximal tensile strength, and a parameter proportionality factor α. Three values of α were used to investigate the influence of the parameter on the SPR. The experimental SPR could satisfactorily be described by the three stage model, however for sodium bicarbonate the tensile strength plateau could not be observed experimentally. The shape of the predicted SPR was to a minor extent influenced by the Kawakita b -1 but the width of the linear region was highly influenced by α. An increased α increased the width of the linear region and thus also the maximal predicted tablet tensile strength. Furthermore, the correspondence between experimental and predicted SPR was influenced by the α value and satisfactory predictions were in general obtained for α = 4.1 indicating the predictive potential of the hybrid approach. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.
Directory of Open Access Journals (Sweden)
Muhammad Nasir Amin
2017-06-01
Full Text Available In this study, the researchers investigated the potential use of locally available waste materials from the lime stone quarry and the granite industry as a partial replacement of cement. Quarry sites and granite industry in the eastern province of Saudi Arabia produces tons of powder wastes in the form of quarry dust (QD and granite sludge (GS, respectively, causing serious environmental problems along with frequent dust storms in the area. According to ASTM C109, identical 50-mm3 specimens were cast throughout this study to evaluate the compressive strength development of mortars (7, 28 and 91 days containing these waste materials. Experimental variables included different percentage replacement of cement with waste materials (GS, QD, fineness of GS, various curing temperatures (20, 40 and 60 °C as local normal and hot environmental temperatures and curing moisture (continuously moist and partially moist followed by air curing. Finally, the results of mortar containing waste materials were compared to corresponding results of control mortar (CM and mortar containing fly ash (FA. The test results indicated that under normal curing (20 °C, moist cured, the compressive strength of mortar containing the different percentage of waste materials (QD, GS, FA and their combinations remained lower than that of CM at all ages. However, the compressive strength of mortar containing waste materials slightly increased with increased fineness of GS and significantly increased under high curing temperatures. It was recommended that more fineness of GS be achieved to use its high percentage replacement with cement (30% or more incorporating local environmental conditions.
Pujari-Palmer, Michael; Robo, Celine; Persson, Cecilia; Procter, Philip; Engqvist, Håkan
2018-01-01
Disease and injuries that affect the skeletal system may require surgical intervention and internal fixation, i.e. orthopedic plate and screw insertion, to stabilize the injury and facilitate tissue repair. If the surrounding bone quality is poor the screws may migrate, or the bone may fail, resulting in fixation failure. While numerous studies have shown that cement augmentation of the interface between bone and implant can increase screw pull-out force, the physical properties of cement that influence pull-out force have not been investigated. The present study sought to determine how the physical properties of high strength calcium phosphate cements (hsCPCs, specifically dicalcium phosphate) affected the corresponding orthopedic screw pull-out force in urethane foam models of "healthy" and "osteoporotic" synthetic bone (Sawbones). In the simplest model, where only the bond strength between screw thread and cement (without Sawbone) was tested, the correlation between pull-out force and cement compressive strength (R 2 = 0.79) was weaker than correlation with total cement porosity (R 2 = 0.89). In open pore Sawbone that mimics "healthy" cancellous bone density the stronger cements produced higher pull-out force (50-60% increase). High strength, low porosity cements also produced higher pull-out forces (50-190% increase) in "healthy" Sawbones with cortical fixation if the failure strength of the cortical material was similar to, or greater than (a metal shell), actual cortical bone. This result is of particular clinical relevance where fixation with a metal plate implant is indicated, as the nearby metal can simulate a thicker cortical shell, thereby increasing the pull-out force of screws augmented with stronger cements. The improvement in pull-out force was apparent even at low augmentation volumes of 0.5mL (50% increase), which suggest that in clinical situations where augmentation volume is limited the stronger, lower porosity calcium phosphate cement (CPC) may
Yin, Peng-Fei; Yang, Sheng-Qi
2018-05-01
As a typical inherently anisotropic rock, layered sandstones can differ from each other in several aspects, including grain size, type of material, type of cementation, and degree of compaction. An experimental study is essential to obtain and convictive evidence to characterize the mechanical behavior of such rock. In this paper, the mechanical behavior of a layered sandstone from Xuzhou, China, is investigated under uniaxial compression and Brazilian test conditions. The loading tests are conducted on 7 sets of bedding inclinations, which are defined as the angle between the bedding plane and horizontal direction. The uniaxial compression strength (UCS) and elastic modulus values show an undulatory variation when the bedding inclination increases. The overall trend of the UCS and elastic modulus values with bedding inclination is decreasing. The BTS value decreases with respect to the bedding inclination and the overall trend of it is approximating a linear variation. The 3D digital high-speed camera images reveal that the failure and fracture of a specimen are related to the surface deformation. Layered sandstone tested under uniaxial compression does not show a typical failure mode, although shear slip along the bedding plane occurs at high bedding inclinations. Strain gauge readings during the Brazilian tests indicate that the normal stress on the bedding plane transforms from compression to tension as the bedding inclination increases. The stress parallel to the bedding plane in a rock material transforms from tension to compression and agrees well with the fracture patterns; "central fractures" occur at bedding inclinations of 0°-75°, "layer activation" occurs at high bedding inclinations of 75°-90°, and a combination of the two occurs at 75°.
Compressive Strength of EN AC-44200 Based Composite Materials Strengthened with α-Al2O3 Particles
Kurzawa A.; Kaczmar J. W.
2017-01-01
The paper presents results of compressive strength investigations of EN AC-44200 based aluminum alloy composite materials reinforced with aluminum oxide particles at ambient and at temperatures of 100, 200 and 250°C. They were manufactured by squeeze casting of the porous preforms made of α-Al2O3 particles with liquid aluminum alloy EN AC-44200. The composite materials were reinforced with preforms characterized by the porosities of 90, 80, 70 and 60 vol. %, thus the alumina content in the co...
Directory of Open Access Journals (Sweden)
Anoop K. Sood
2012-01-01
Full Text Available Fused deposition modelling (FDM is gaining distinct advantage in manufacturing industries because of its ability to manufacture parts with complex shapes without any tooling requirement and human interface. The properties of FDM built parts exhibit high dependence on process parameters and can be improved by setting parameters at suitable levels. Anisotropic and brittle nature of build part makes it important to study the effect of process parameters to the resistance to compressive loading for enhancing service life of functional parts. Hence, the present work focuses on extensive study to understand the effect of five important parameters such as layer thickness, part build orientation, raster angle, raster width and air gap on the compressive stress of test specimen. The study not only provides insight into complex dependency of compressive stress on process parameters but also develops a statistically validated predictive equation. The equation is used to find optimal parameter setting through quantum-behaved particle swarm optimization (QPSO. As FDM process is a highly complex one and process parameters influence the responses in a non linear manner, compressive stress is predicted using artificial neural network (ANN and is compared with predictive equation.
DEFF Research Database (Denmark)
Hansen, Soren Gustenhoff; Lauridsen, Jorgen Trankjaer; Hoang, Linh Cao
2018-01-01
design parameters and conditions on the anisotropy. This includes the influence of reinforcement, w/c-ratio, curing time, load history and structural geometry. For this purpose, cores were drilled out at different angles from beam- and slab specimens for compressive testing. The main findings include: a...
International Nuclear Information System (INIS)
Wei, Q.; Jiao, T.; Ramesh, K.T.; Ma, E.; Kecskes, L.J.; Magness, L.; Dowding, R.; Kazykhanov, V.U.; Valiev, R.Z.
2006-01-01
We have systematically investigated the quasi-static and dynamic mechanical behavior (especially dynamic failure) of ultra-fine grained (UFG) tungsten (W) under uniaxial compression. The starting material is of commercial purity and large grain size. We utilized severe plastic deformation to achieve the ultrafine microstructure characterized by grains and subgrains with sizes of ∼500 nm, as identified by transmission electron microscopy. Results of quasi-static compression show that the UFG W behaves in an elastic-nearly perfect plastic manner (i.e., vanishing strain hardening), with its flow stress approaching 2 GPa, close to twice that of conventional coarse grain W. Post-mortem examinations of the quasi-statically loaded samples show no evidence of cracking, in sharp contrast to the behavior of conventional W (where axial cracking is usually observed). Under uniaxial dynamic compression (strain rate ∼10 3 s -1 ), the true stress-true strain curves of the UFG W exhibit significant flow softening, and the peak stress is ∼3 GPa. Furthermore, the strain rate sensitivity of the UFG W is reduced to half the value of the conventional W. Both in situ high-speed photography and post-mortem examinations reveal shear localization and as a consequence, cracking of the UFG W under dynamic uniaxial compression. These observations are consistent with recent observations on other body-centered cubic metals with nanocrystalline or ultrafine microstructures. The experimental results are discussed using existing models for adiabatic shear localization in metals
Smoothing and instability with magnetic field in a non-uniformly laser-irradiated planar target
International Nuclear Information System (INIS)
Bell, A.R.; Epperlein, E.M.
1986-01-01
Calculations are presented of the magneto-hydrodynamic response of a planar target to non-uniformities in energy deposition by a laser. The amplitude of the non-uniformities are assumed small and the equations are linearised in small perturbations about the solution for steady planar ablation driven by uniform laser energy deposition. The grad(n)xgrad(T) magnetic field source is included, along with Nernst convection and the Righi-Leduc heat flow. The magnetic field is shown to give a small increase in smoothing. A source term for magnetic field is included to simulate the effects of the Weibel instability. The instability is not strong enough to overcome the smoothing processes under the present assumptions. (author)
Non-Uniform Dose Mapping Controlled by Modulated Vertical and Horizontal Scans
International Nuclear Information System (INIS)
Ninomiya, S.; Kimura, Y.; Kudo, T.; Ochi, A.; Toda, R.; Tsukihara, M.; Sato, F.; Fuse, G.; Ueno, K.; Sugitani, M.
2008-01-01
Since geometries of semi-conductor devices continue to shrink, the requirement for each process becomes severer to keep uniformity of electrical parameters of the semi-conductor devices. A larger wafer also causes larger variations. Thus it has been strongly required for ion implantation process to compensate for the variations from other processes because of its good dose controllability. A newly developed mapping of intentional non-uniform dosage system, which is named 'MIND system', is implemented in SEN's single-wafer-type implanters. The MIND system controls both horizontal and vertical scan speed simultaneously. Intentional two-dimensional non-uniform profiles of sheet resistance, such as concentric and eccentric profiles, are obtained only by single-step ion implantation.
Energy-Efficient Algorithm for Sensor Networks with Non-Uniform Maximum Transmission Range
Directory of Open Access Journals (Sweden)
Yimin Yu
2011-06-01
Full Text Available In wireless sensor networks (WSNs, the energy hole problem is a key factor affecting the network lifetime. In a circular multi-hop sensor network (modeled as concentric coronas, the optimal transmission ranges of all coronas can effectively improve network lifetime. In this paper, we investigate WSNs with non-uniform maximum transmission ranges, where sensor nodes deployed in different regions may differ in their maximum transmission range. Then, we propose an Energy-efficient algorithm for Non-uniform Maximum Transmission range (ENMT, which can search approximate optimal transmission ranges of all coronas in order to prolong network lifetime. Furthermore, the simulation results indicate that ENMT performs better than other algorithms.
Effects of non-uniform embedments on earthquake responses of nuclear reactor building
International Nuclear Information System (INIS)
Koyanagi, Y.; Okamoto, S.; Yoshida, K.; Inove, H.
1989-01-01
The nuclear reactor buildings have the portion embedded in soil. In the seismic design of such structures, it is essential to consider the effects of the embedment on the earthquake response. Most studies on these effects, however, assume the uniform embedment, i.e. the depth of the embedment is constant, which is convenient for the design and analysis. The behavior of the earthquake response considering the three-dimensional aspects of non-uniform embedment has not been made clear yet. In this paper, the authors evaluate the effects of the non-uniform embedment in an inclined ground surface on the earthquake response of a nuclear reactor building as illustrated. A typical PWR type reactor building is chosen as an analysis structure model. Four different types of embedment are set up for the comparison study. The three-dimensional analysis is carried out considering the geometry of embedment
Tunable pinning effects produced by non-uniform antidot arrays in YBCO thin films
Energy Technology Data Exchange (ETDEWEB)
George, J.; Jones, A.; Al-Qurainy, M. [Institute for Superconducting and Electronic Materials, University of Wollongong, NSW (Australia); Fedoseev, S.A. [Institute for Superconducting and Electronic Materials, University of Wollongong, NSW (Australia); Centre for Medical Radiation Physics, University of Wollongong, NSW (Australia); Rosenfeld, A. [Centre for Medical Radiation Physics, University of Wollongong, NSW (Australia); Pan, A.V. [Institute for Superconducting and Electronic Materials, University of Wollongong, NSW (Australia); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation)
2017-04-15
Uniform, graded and spaced arrays of 3 μm triangular antidots in pulsed laser deposited YBa{sub 2}Cu{sub 3}O{sub 7} (YBCO) superconducting thin films are compared by examining the improvements in the critical current density J{sub c} they produced. The comparison is made to establish the role of their lithographically defined (non-)uniformity and the effectiveness to control and/or enhance the critical current density. It is found that almost all types of non-uniform arrays, including graded ones enhance J{sub c} over the broad applied magnetic field and temperature range due to the modified critical state. Whereas uniform arrays of antidots either reduce or produce no effect on J{sub c} compared to the original (as-deposited) thin films. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Selective exfoliation of single-layer graphene from non-uniform graphene grown on Cu
International Nuclear Information System (INIS)
Lim, Jae-Young; Lee, Jae-Hyun; Jang, Hyeon-Sik; Whang, Dongmok; Joo, Won-Jae; Hwang, SungWoo
2015-01-01
Graphene growth on a copper surface via metal-catalyzed chemical vapor deposition has several advantages in terms of providing high-quality graphene with the potential for scale-up, but the product is usually inhomogeneous due to the inability to control the graphene layer growth. The non-uniform regions strongly affect the reliability of the graphene in practical electronic applications. Herein, we report a novel graphene transfer method that allows for the selective exfoliation of single-layer graphene from non-uniform graphene grown on a Cu foil. Differences in the interlayer bonding energy are exploited to mechanically separate only the top single-layer graphene and transfer this to an arbitrary substrate. The dry-transferred single-layer graphene showed electrical characteristics that were more uniform than those of graphene transferred using conventional wet-etching transfer steps. (paper)
Many-junction photovoltaic device performance under non-uniform high-concentration illumination
Valdivia, Christopher E.; Wilkins, Matthew M.; Chahal, Sanmeet S.; Proulx, Francine; Provost, Philippe-Olivier; Masson, Denis P.; Fafard, Simon; Hinzer, Karin
2017-09-01
A parameterized 3D distributed circuit model was developed to calculate the performance of III-V solar cells and photonic power converters (PPC) with a variable number of epitaxial vertically-stacked pn junctions. PPC devices are designed with many pn junctions to realize higher voltages and to operate under non-uniform illumination profiles from a laser or LED. Performance impacts of non-uniform illumination were greatly reduced with increasing number of junctions, with simulations comparing PPC devices with 3 to 20 junctions. Experimental results using Azastra Opto's 12- and 20-junction PPC illuminated by an 845 nm diode laser show high performance even with a small gap between the PPC and optical fiber output, until the local tunnel junction limit is reached.
Lücken, Leonhard; Yanchuk, Serhiy; Popovych, Oleksandr V.; Tass, Peter A.
2013-01-01
Several brain diseases are characterized by abnormal neuronal synchronization. Desynchronization of abnormal neural synchrony is theoretically compelling because of the complex dynamical mechanisms involved. We here present a novel type of coordinated reset (CR) stimulation. CR means to deliver phase resetting stimuli at different neuronal sub-populations sequentially, i.e., at times equidistantly distributed in a stimulation cycle. This uniform timing pattern seems to be intuitive and actually applies to the neural network models used for the study of CR so far. CR resets the population to an unstable cluster state from where it passes through a desynchronized transient, eventually resynchronizing if left unperturbed. In contrast, we show that the optimal stimulation times are non-uniform. Using the model of weakly pulse-coupled neurons with phase response curves, we provide an approach that enables to determine optimal stimulation timing patterns that substantially maximize the desynchronized transient time following the application of CR stimulation. This approach includes an optimization search for clusters in a low-dimensional pulse coupled map. As a consequence, model-specific non-uniformly spaced cluster states cause considerably longer desynchronization transients. Intriguingly, such a desynchronization boost with non-uniform CR stimulation can already be achieved by only slight modifications of the uniform CR timing pattern. Our results suggest that the non-uniformness of the stimulation times can be a medically valuable parameter in the calibration procedure for CR stimulation, where the latter has successfully been used in clinical and pre-clinical studies for the treatment of Parkinson's disease and tinnitus. PMID:23750134
Research of non-uniform multiple hole straighteners for measuring flow rate
International Nuclear Information System (INIS)
Wen Duanzhong; Zhong Dezhen; Cai Zhuti
1989-01-01
Standard throttling flowmeters are widely used in process flow rate measurement. Enough upstream and downstream straight pipe are necessary for it. If not, the error will be increased. Mounting straightener is an effective way for solving this problem. Advantages of non-uniform multiple hole straighteners studied by authors are good results for straighting, simple in Structure, convenient for mounting and low cost. So it can be popularized in many applications
The use of non-uniform drowning terminology: a follow-up study.
Schmidt, Andrew C; Sempsrott, Justin R; Szpilman, David; Queiroga, Ana Catarina; Davison, Matt S; Zeigler, Ryan J; McAlister, Sean J
2017-07-17
In 2002, the World Congress on Drowning developed a uniform definition for drowning. The aim of this study is to determine the prevalence of "non-uniform drowning terminology" (NUDT) and "non-uniform drowning definitions" (NUDD) in peer-reviewed scientific literature from 2010 to 2016, and compare these findings with those from our unpublished study performing a similar analysis on literature from 2003 to 2010. A systematic review was performed using drowning-specific search terms in Pubmed and Web of Science. Titles and abstracts published between July 2010 and January 2016 were screened for relevance to the study focus. Articles meeting screening criteria were reviewed for exclusion criteria to produce the final group of studies. These articles were reviewed by four reviewers for NUDT and NUDD. The Fisher exact test was used to determine any statistically significant changes. The final group of studies included 167 articles. A total of 53 articles (32%) utilized NUDT, with 100% of these including the term "near drowning". The proportion of articles utilizing NUDT was significantly less than reported by our previous study (p drowning (uniform or non-uniform), with 15% of these utilizing NUDD. Our study reveals a statistically significant improvement over the past thirteen years in the use of uniform drowning terminology in peer-reviewed scientific literature, although year-to-year variability over the current study period does not yield an obvious trend. Of the articles reviewed during the 2010-2016 study period, 32% included outdated and non-uniform drowning terminology and definitions. While this reveals an absolute decrease of 11% as compared with the previous study period (2003-2010), there is still significant room for improvement.
Influence of Non-uniform Temperature Field on Spectra of Fibre Bragg Grating
International Nuclear Information System (INIS)
Yan, Zhou; Xing-Fang, He; Xiao-Yong, Fang; Jie, Yuan; Li-Qun, Yin; Mao-Sheng, Cao
2009-01-01
We simulate the spectrum characteristics of fibre Bragg grating (FBG) with non-uniform temperature using the transmission matrix method, and the results are analysed. It is found that firstly the modulated coefficient of average refractive index is a very important parameter that influences the spectrum characteristic of the fibre Bragg grating, and secondly the spectrum curves are different in different temperature fields at the same parameter. Hence, we can determine the metrical temperature by analysing the spectrum of fibre Bragg grating
Human thermal sensation and comfort in a non-uniform environment with personalized heating.
Deng, Qihong; Wang, Runhuai; Li, Yuguo; Miao, Yufeng; Zhao, Jinping
2017-02-01
Thermal comfort in traditionally uniform environment is apparent and can be improved by increasing energy expenses. To save energy, non-uniform environment implemented by personalized conditioning system attracts considerable attention, but human response in such environment is unclear. To investigate regional- and whole-body thermal sensation and comfort in a cool environment with personalized heating. In total 36 subjects (17 males and 19 females) including children, adults and the elderly, were involved in our experiment. Each subject was first asked to sit on a seat in an 18°C chamber (uniform environment) for 40min and then sit on a heating seat in a 16°C chamber (non-uniform environment) for another 40min after 10min break. Subjects' regional- and whole-body thermal sensation and comfort were surveyed by questionnaire and their skin temperatures were measured by wireless sensors. We statistically analyzed subjects' thermal sensation and comfort and their skin temperatures in different age and gender groups and compared them between the uniform and non-uniform environments. Overall thermal sensation and comfort votes were respectively neutral and just comfortable in 16°C chamber with personalized heating, which were significantly higher than those in 18°C chamber without heating (pthermal sensation and comfort was consistent in subjects of different age and gender. However, adults and the females were more sensitive to the effect of personalized heating and felt cooler and less comfort than children/elderly and the males respectively. Variations of the regional thermal sensation/comfort across human body were consistent with those of skin temperature. Personalized heating significantly improved human thermal sensation and comfort in non-uniform cooler environment, probably due to the fact that it increased skin temperature. However, the link between thermal sensation/comfort and variations of skin temperature is rather complex and warrant further
On the Super-Turing Computational Power of Non-Uniform Families of Neuromata
Czech Academy of Sciences Publication Activity Database
Wiedermann, Jiří
2002-01-01
Roč. 12, č. 5 (2002), s. 509-516 ISSN 1210-0552. [SOFSEM 2002 Workshop on Soft Computing. Milovy, 28.11.2002-29.11.2002] R&D Projects: GA ČR GA201/00/1489 Institutional research plan: AV0Z1030915 Keywords : neuromata * Turing machines with advice * non-uniform computational complexity * super-Turing computational power Subject RIV: BA - General Mathematics
Radiation flaw detector for testing non-uniform surface bodies of revolution
International Nuclear Information System (INIS)
Valevich, M.I.
1984-01-01
Radiation flaw detector for testing bodies of revolution with non-uniform surface, welded joints, etc., based on spatial filtration and differentiation of ionizing radiation flux has been described. The calculation of the most important unit of flaw detector - integrators - is made. Experimental studies of the sensitivity have shown, that the radiation flaw detector can be used for rapid testing of products with the sensitivity comparable with the sensitivity of radiographic testing of steel
Enceladus's crust as a non-uniform thin shell: I tidal deformations
Beuthe, Mikael
2018-03-01
The geologic activity at Enceladus's south pole remains unexplained, though tidal deformations are probably the ultimate cause. Recent gravity and libration data indicate that Enceladus's icy crust floats on a global ocean, is rather thin, and has a strongly non-uniform thickness. Tidal effects are enhanced by crustal thinning at the south pole, so that realistic models of tidal tectonics and dissipation should take into account the lateral variations of shell structure. I construct here the theory of non-uniform viscoelastic thin shells, allowing for depth-dependent rheology and large lateral variations of shell thickness and rheology. Coupling to tides yields two 2D linear partial differential equations of the fourth order on the sphere which take into account self-gravity, density stratification below the shell, and core viscoelasticity. If the shell is laterally uniform, the solution agrees with analytical formulas for tidal Love numbers; errors on displacements and stresses are less than 5% and 15%, respectively, if the thickness is less than 10% of the radius. If the shell is non-uniform, the tidal thin shell equations are solved as a system of coupled linear equations in a spherical harmonic basis. Compared to finite element models, thin shell predictions are similar for the deformations due to Enceladus's pressurized ocean, but differ for the tides of Ganymede. If Enceladus's shell is conductive with isostatic thickness variations, surface stresses are approximately inversely proportional to the local shell thickness. The radial tide is only moderately enhanced at the south pole. The combination of crustal thinning and convection below the poles can amplify south polar stresses by a factor of 10, but it cannot explain the apparent time lag between the maximum plume brightness and the opening of tiger stripes. In a second paper, I will study the impact of a non-uniform crust on tidal dissipation.
Image restoration from non-uniform magnetic field influence for direct Fourier NMR imaging
International Nuclear Information System (INIS)
Sekihara, K.; Kuroda, M.; Kohno, H.
1984-01-01
A new technique is proposed for NMR image restoration from the influence of main magnetic field non-uniformities. This technique is applicable to direct Fourier NMR imaging. The mathematical basis and details of this technique are fully described. Modification to include image restoration from non-linear field gradient influence is also presented. Computer simulation demonstrates the effectiveness of this technique for both Fourier zeugmatography and spin-warp imaging. (author)
Effect of shear strength on Hugoniot-compression curve and the equation of state of tungsten (W)
Energy Technology Data Exchange (ETDEWEB)
Mashimo, Tsutomu, E-mail: mashimo@gpo.kumamoto-u.ac.jp; Liu, Xun [Institute of Pulsed Power Science, Kumamoto University, Kumamoto 860-8555 (Japan); Kodama, Masao [Sojo University, Kumamoto 860-0082 (Japan); Zaretsky, Eugene [Ben-Gurion University of the Negev, P.O. Box 653, Beer Sheva 84105 (Israel); Katayama, Masahide [Itochu Techno-Solutions Corporation, Tokyo 100-6080 (Japan); Nagayama, Kunihiko [Kyushu University, Fukuoka 812-8581 (Japan)
2016-01-21
The Hugoniot data for highly dense polycrystalline tungsten were obtained for pressures above 200 GPa, and the equation of state (EOS) was determined taking into account shear strength effects. For this study, we have made some improvements in measurement system and analyses of the shock wave data. Symmetric-impact Hugoniot measurements were performed using the high-time resolution streak camera system equipped on a one-stage powder gun and two-stage light gas gun, where the effects of tilting and bowing of flyer plate on the Hugoniot data were carefully considered. The shock velocity–particle velocity (U{sub S}–U{sub P}) Hugoniot relation in the plastic regime was determined to be U{sub S} = 4.137 + 1.242U{sub P} km/s (U{sub P} < 2 km/s). Ultrasonic and Velocity Interferometer System for Any Reflector measurements were also performed in this study. The zero-intercept value of the U{sub S}–U{sub P} Hugoniot relation was found to be slightly larger than the ultrasonic bulk sound velocity (4.023 km/s). The hypothetical hydrostatic isothermal U{sub s}–U{sub p} Hugoniot curve, which corresponds to the hydrostatic isothermal compression curve derived from the Hugoniot data using the strength data, converged to the bulk sound velocity, clearly showing shear strength dependence in the Hugoniot data. The EOS for tungsten is derived from the hydrostatic isothermal compression curve using the strength data.
Effect of shear strength on Hugoniot-compression curve and the equation of state of tungsten (W)
International Nuclear Information System (INIS)
Mashimo, Tsutomu; Liu, Xun; Kodama, Masao; Zaretsky, Eugene; Katayama, Masahide; Nagayama, Kunihiko
2016-01-01
The Hugoniot data for highly dense polycrystalline tungsten were obtained for pressures above 200 GPa, and the equation of state (EOS) was determined taking into account shear strength effects. For this study, we have made some improvements in measurement system and analyses of the shock wave data. Symmetric-impact Hugoniot measurements were performed using the high-time resolution streak camera system equipped on a one-stage powder gun and two-stage light gas gun, where the effects of tilting and bowing of flyer plate on the Hugoniot data were carefully considered. The shock velocity–particle velocity (U S –U P ) Hugoniot relation in the plastic regime was determined to be U S = 4.137 + 1.242U P km/s (U P < 2 km/s). Ultrasonic and Velocity Interferometer System for Any Reflector measurements were also performed in this study. The zero-intercept value of the U S –U P Hugoniot relation was found to be slightly larger than the ultrasonic bulk sound velocity (4.023 km/s). The hypothetical hydrostatic isothermal U s –U p Hugoniot curve, which corresponds to the hydrostatic isothermal compression curve derived from the Hugoniot data using the strength data, converged to the bulk sound velocity, clearly showing shear strength dependence in the Hugoniot data. The EOS for tungsten is derived from the hydrostatic isothermal compression curve using the strength data
CHF multiplier of subcooled flow boiling for non-uniform heating conditions in swirl tube
International Nuclear Information System (INIS)
Inasaka, F.; Nariai, H.
1994-01-01
The high heat flux components of fusion reactors, such as divertor plates and beam dumps of neutral beam injectors, are estimated to be subjected to very high heat loads more than 10 MW/m 2 . Critical heat flux (CHF), which determines the upper limit of heat removal, is one of the most important problems in designing cooling systems. For practical applications in cooling systems, subcooled flow boiling in water combined with swirl-flow in tubes with internal twisted tape is thought to be the most superior for CHF characteristics in fusion reactor components, heat by irradiation comes in from one side of the wall, and cooling channel is then under circumferentially non-uniform heating condition. Authors have conducted the experiments on the CHF with internal twisted tapes under circumferentially non-uniform heating conditions and showed that when the intensity of non-uniformity increased, q cH (peak heat flux at burnout under nonuniform heating condition) in tube with internal twisted tape increased above the q c,unif (CHF under uniform heating condition), though the average qualities were the same for both cases. They also showed that this CHF enhancement was not seen in smooth tubes without tape under the same average qualities
Bridge density functional approximation for non-uniform hard core repulsive Yukawa fluid
International Nuclear Information System (INIS)
Zhou Shiqi
2008-01-01
In this work, a bridge density functional approximation (BDFA) (J. Chem. Phys. 112, 8079 (2000)) for a non-uniform hard-sphere fluid is extended to a non-uniform hard-core repulsive Yukawa (HCRY) fluid. It is found that the choice of a bulk bridge functional approximation is crucial for both a uniform HCRY fluid and a non-uniform HCRY fluid. A new bridge functional approximation is proposed, which can accurately predict the radial distribution function of the bulk HCRY fluid. With the new bridge functional approximation and its associated bulk second order direct correlation function as input, the BDFA can be used to well calculate the density profile of the HCRY fluid subjected to the influence of varying external fields, and the theoretical predictions are in good agreement with the corresponding simulation data. The calculated results indicate that the present BDFA captures quantitatively the phenomena such as the coexistence of solid-like high density phase and low density gas phase, and the adsorption properties of the HCRY fluid, which qualitatively differ from those of the fluids combining both hard-core repulsion and an attractive tail. (condensed matter: structure, thermal and mechanical properties)
Characterization and Processing of Non-Uniformities in Back-Illuminated CCDs
Lemm, Alia D.; Della-Rose, Devin J.; Maddocks, Sally
2018-01-01
In astronomical photometry, Charged Coupled Device (CCD) detectors are used to achieve high precision photometry and must be properly calibrated to correct for noise and pixel non-uniformities. Uncalibrated images may contain bias offset, dark current, bias structure and uneven illumination. In addition, standard data reduction is often not sufficient to “normalize” imagery to single-digit millimagnitude (mmag) precision. We are investigating an apparent non-uniformity, or interference pattern, in a back-illuminated sensor, the Alta U-47, attached to a DFM Engineering 41-cm Ritchey-Chrétien f/8 telescope. Based on the amplitude of this effect, we estimate that instrument magnitude peak-to-valley deviations of 50 mmag or more may result. Our initial testing strongly suggests that reflected skylight from high pressure sodium city lights may be the cause of this interference pattern. Our research goals are twofold: to fully characterize this non-uniformity and to determine the best method to remove this interference pattern from our reduced CCD images.
Krupiński, Michał; Bareła, Jaroslaw; Firmanty, Krzysztof; Kastek, Mariusz
2013-10-01
Uneven response of particular detectors (pixels) to the same incident power of infrared radiation is an inherent feature of microbolometer focal plane arrays. As a result an image degradation occurs, known as Fixed Pattern Noise (FPN), which distorts the thermal representation of an observed scene and impairs the parameters of a thermal camera. In order to compensate such non-uniformity, several NUC correction methods are applied in digital data processing modules implemented in thermal cameras. Coefficients required to perform the non-uniformity correction procedure (NUC coefficients) are determined by calibrating the camera against uniform radiation sources (blackbodies). Non-uniformity correction is performed in a digital processing unit in order to remove FPN pattern in the registered thermal images. Relevant correction coefficients are calculated on the basis of recorded detector responses to several values of radiant flux emitted from reference IR radiation sources (blackbodies). The measurement of correction coefficients requires specialized setup, in which uniform, extended radiation sources with high temperature stability are one of key elements. Measurement stand for NUC correction developed in Institute of Optoelectronics, MUT, comprises two integrated extended blackbodies with the following specifications: area 200×200 mm, stabilized absolute temperature range +15 °C÷100 °C, and uniformity of temperature distribution across entire surface +/-0.014 °C. Test stand, method used for the measurement of NUC coefficients and the results obtained during the measurements conducted on a prototype thermal camera will be presented in the paper.
Non-uniform cosine modulated filter banks using meta-heuristic algorithms in CSD space
Directory of Open Access Journals (Sweden)
Shaeen Kalathil
2015-11-01
Full Text Available This paper presents an efficient design of non-uniform cosine modulated filter banks (CMFB using canonic signed digit (CSD coefficients. CMFB has got an easy and efficient design approach. Non-uniform decomposition can be easily obtained by merging the appropriate filters of a uniform filter bank. Only the prototype filter needs to be designed and optimized. In this paper, the prototype filter is designed using window method, weighted Chebyshev approximation and weighted constrained least square approximation. The coefficients are quantized into CSD, using a look-up-table. The finite precision CSD rounding, deteriorates the filter bank performances. The performances of the filter bank are improved using suitably modified meta-heuristic algorithms. The different meta-heuristic algorithms which are modified and used in this paper are Artificial Bee Colony algorithm, Gravitational Search algorithm, Harmony Search algorithm and Genetic algorithm and they result in filter banks with less implementation complexity, power consumption and area requirements when compared with those of the conventional continuous coefficient non-uniform CMFB.
International Nuclear Information System (INIS)
Kenjeres, Sasa
2008-01-01
The paper reports on a comprehensive mathematical model for simulations of blood flow under the presence of strong non-uniform magnetic fields. The model consists of a set of Navier-Stokes equations accounting for the Lorentz and magnetisation forces, and a simplified set of Maxwell's equations (Biot-Savart/Ampere's law) for treating the imposed magnetic fields. The relevant hydrodynamic and electromagnetic properties of human blood were taken from the literature. The model is then validated for different test cases ranging from a simple cylindrical geometry to real-life right-coronary arteries in humans. The time-dependency of the wall-shear-stress for different stenosis growth rates and the effects of the imposed strong non-uniform magnetic fields on the blood flow pattern are presented and analysed. It is concluded that an imposed non-uniform magnetic field can create significant changes in the secondary flow patterns, thus making it possible to use this technique for optimisations of targeted drug delivery
Effect of non-uniform surface resistance on the quality factor of superconducting niobium cavity
Tan, Weiwei; Lu, Xiangyang; Yang, Ziqin; Zhao, Jifei; Yang, Deyu; Yang, Yujia
2016-08-01
The formula Rs = G /Q0 is commonly used in the calculation of the surface resistance of radio frequency niobium superconducting cavities. The applying of such equation is under the assumption that surface resistance is consistent over the cavity. However, the distribution of the magnetic field varies over the cavity. The magnetic field in the equator is much higher than that in the iris. According to Thermal Feedback Theory, it leads non-uniform distribution of the density of heat flux, which results in a different temperature distribution along the cavity inter surface. The BCS surface resistance, which depends largely on the temperature, is different in each local inner surface. In this paper, the effect of surface non-uniform resistance on the quality factor has been studied, through the calculation of Q0 in the original definition of it. The results show that it is necessary to consider the non-uniform distribution of magnetic field when the accelerating field is above 20 MV/m for TESLA cavities. Also, the effect of inhomogeneity of residual resistance on the quality factor is discussed. Its distribution barely affects the quality factor.
On the burnout in annular channels at non-uniform heat release distribution in length
International Nuclear Information System (INIS)
Ornatskij, A.P.; Chernobaj, V.A.; Vasil'ev, A.F.; Struts, G.V.
1982-01-01
The effect of axial heat release non-uniformity on the conditions of the burnout in annular channels is investigated. The investigation is carried out in annular channels with different laws of heat flux density distribution by channel length. The heat release non-uniformity coefficient was varied from 4.4 to 10, the pressure from 9.8 to 17.6 MPa, mass rate from 500 to 1700 kg (m 2 xS), liquid temperature (chemically desalted water) at the channel inlet constituted 30-300 deg C. The experiments have been performed at the test bench with a closed circulation circuit. The data obtained testify to the fact that under non-uniform heat release the influence of main operating parameters on the value of critical power is of the same character as under uniform heat release. The character of wall temperature variation by channel length before the burnout is determined by the form of heat supply temperature profile. The temperature maximum is observed in the region lying behind the cross section with maximum heat flux. The conclusion is drawn that the dominant influence on the position of the cross section in which the burnout arises is exerted by the form of heat flux density distribution by length. Independently of this distribution form the burnout developes when the vapour content near the wall reaches a limiting value
The magneto-optical properties of non-uniform graphene nanoribbons
Chung, Hsien-Ching; Lin, Ming-Fa
2015-03-01
When synthesizing few-layer graphene nanoribbons (GNRs), non-uniform GNRs would be made simultaneously. Recently, the non-uniform GNRs, which is a stack of two GNRs with unequal widths, have been fabricated by mechanically exfoliated from bulk graphite. Some theoretical predictions have been reported, such as gap opening and transport properties. Under the influence of magnetic fields, magnetic quantization takes place and drastically changes the electronic properties. By tuning the geometric configuration, four categories of magneto-electronic spectra are exhibited. (1) The spectrum is mostly contributed by quasi-Landau levels (QLLs) of monolayer GNRs. (2) The spectrum displays two groups of QLLs, and the non-uniform GNR behaves like a bilayer one. (3) An intermediate category, the spectrum is composite disordered. (4) The spectrum presents the coexistence of monolayer and bilayer spectra. In this work, the magneto-electronic and optical properties for different geometric configurations are given, such as energy dispersions, density of states, wave functions, and magneto-absorption spectra are presented. Furthermore, the transformation between monolayer and bilayer spectra as well as the coexistence of monolayer and bilayer spectra are discussed in detail. One of us (Hsien-Ching Chung) thanks Ming-Hui Chung and Su-Ming Chen for financial support. This work was supported in part by the National Science Council of Taiwan under Grant Number 98-2112-M-006-013-MY4.
Compressive Strength Prediction of Square Concrete Columns Retrofitted with External Steel Collars
Directory of Open Access Journals (Sweden)
Pudjisuryadi, P.
2013-01-01
Full Text Available Transverse confining stress in concrete members, commonly provided by transverse reinforcement, has been recognized to enhance strength and ductility. Nowadays, the confining method has been further developed to external confinement approach. This type of confinement can be used for retrofitting existing concrete columns. Many external confining techniques have been proven to be successful in retrofitting circular columns. However, for square or rectangular columns, providing effective confining stress by external retrofitting method is not a simple task due to high stress concentration at column’s corners. This paper proposes an analytical model to predict the peak strength of square concrete columns confined by external steel collars. Comparison with the experimental results showed that the model can predict the peak strength reasonably well. However, it should be noted that relatively larger amount of steel is needed to achieve comparable column strength enhancement when it is compared with those of conve tional internally-confined columns.
STUDY OF EXPERIMENTAL SAMPLES WITH DIFFERENT CONFIGURATIONS AT THE JOINTS COMPRESSIVE STRENGTH
Directory of Open Access Journals (Sweden)
E. N. Magomedova
2013-01-01
Full Text Available The article marked the behavior of concrete under the action of water, the effect of moisture and water saturation on the performance and durability of concrete waterproofing; offered special configuration interface, allowing to increase the strength characteristics of the concrete structure, the results of experimental studies; conclusions about the relationship configuration of joints and their strength.
The effects of friction on the compressive behaviour of high strength steels
International Nuclear Information System (INIS)
Ashton, M.; Parry, D.J.
1997-01-01
An investigation, covering a wide range of strain rate and temperature, has been performed into the effects of interfacial friction on the compressive properties of an armour plate steel. In order to calculate the coefficient of friction, ring tests were carried out and the Avitzur analysis applied. In general, coefficients of friction decreased with increasing temperature and strain rate. Other specimen observations indicated the same friction trends. It is essential that friction corrections be applied if meaningful results are to be obtained. (orig.)
Directory of Open Access Journals (Sweden)
Ersoy Hakan
2012-10-01
Full Text Available
ABSTRACT
Uniaxial compressive strength (UCS deals with materials' to ability to withstand axially-directed pushing forces and especially considered to be rock materials' most important mechanical properties. However, the UCS test is an expensive, very time-consuming test to perform in the laboratory and requires high-quality core samples having regular geometry. Empirical equations were thus proposed for predicting UCS as a function of rocks' index properties. Analytical hierarchy process and multiple regression analysis based methodology were used (as opposed to traditional linear regression methods on data-sets obtained from carbonate rocks in NE Turkey. Limestone samples ranging from Devonian to late Cretaceous ages were chosen; travertine-onyx samples were selected from morphological environments considering their surface environmental conditions Test results from experiments carried out on about 250 carbonate rock samples were used in deriving the model. While the hierarchy model focused on determining the most important index properties affecting on UCS, regression analysis established meaningful relationships between UCS and index properties; 0. 85 and 0. 83 positive coefficient correlations between the variables were determined by regression analysis. The methodology provided an appropriate alternative to quantitative estimation of UCS and avoided the need for tedious and time consuming laboratory testing
RESUMEN
La resistencia a la compresión uniaxial (RCU trata con la capacidad de los materiales para soportar fuerzas empujantes dirigidas axialmente y, especialmente, es considerada ser uno de las más importantes propiedades mecánicas de
International Nuclear Information System (INIS)
Huang, Lin; Jiang, Lin; Topping, Troy D.; Dai, Chen; Wang, Xin; Carpenter, Ryan; Haines, Christopher; Schoenung, Julie M.
2017-01-01
In this work a novel process methodology to concurrently improve the compressive strength (2078 MPa at a strain rate of 5 × 10"−"4 s"−"1) and strain-to-failure (over 40%) of bulk tungsten materials has been described. The process involves the in situ formation of intragranular tungsten oxide nanoparticles, facilitated by the application of a pressure of 1 GPa at a low sintering temperature of 1200 °C during spark plasma sintering (SPS). The results show that the application of a high pressure of 1 GPa during SPS significantly accelerates the densification process. Concurrently, the second phase oxide nanoparticles with an average grain size of 108 nm, which are distributed within the interiors of the W grains, simultaneously provide strengthening and plasticity by inhibiting grain growth, and generating, blocking, and storing dislocations. - Graphical abstract: In this work a novel process methodology to concurrently improve the compressive strength (2078 MPa at a strain rate of 5 × 10"−"4 s"−"1) and strain-to-failure (over 40%) of bulk W materials has been described. The process involves the in situ formation of intragranular tungsten oxide nanoparticles, facilitated by the application of a pressure of 1 GPa at a low sintering temperature of 1200 °C during spark plasma sintering (SPS).
Directory of Open Access Journals (Sweden)
João Alexandre Paschoalin Filho
2016-04-01
Full Text Available This paper presents the evaluation of compressive strength of soil-cement bricks obtained by the inclusion in their mixture of PET flakes through mineral water bottles grinding. The Polyethylene Terephthalate (PET has been characterized by its difficulty of disaggregation in nature, requiring a long period for this. On the other hand, with the increase in civil construction activities the demand for raw material also increases, causing considerable environmental impacts. In this context, the objective of this research is to propose a simple methodology, preventing its dumping and accumulation in irregular areas, and reducing the demand of raw materials by the civil construction industry. The results showed that compressive strengths obtained were lower than recommended by NBR 8491 (Associação Brasileira de Normas Técnicas [ABNT], 2012b at seven days of curing time. However, they may be used as an alternative solution in masonry works in order to not submit themselves to great loads or structural functions. The studied bricks also presented water absorption near to recommended values by NBR 8491 (ABNT, 2012b. Manufacturing costs were also determined for this brick, comparing it with the costs of other brick types. Each brick withdrew from circulation approximately 300 g of PET waste. Thus, for an area of 1 m2 the studied bricks can promote the withdrawal of approximately 180 beverage bottles of 2 L capacity.
Triyono, Joko; Pratama, Aditya; Sukanto, Heru; Nugroho, Yohanes; Wijayanta, Agung Tri
2018-02-01
This study aimed to investigate the effect of heat bed temperature of 3D bioprinter toward compressive strength and hardness bovine bone hydroxyapatite scaffold for bone filler applications. BHA-glycerin mixed with a ratio of 1:1, and keep it for 24 hours. After the homogenization process acquired, bio-Ink with shaped slurry will be used as a material for a 3D printer. The printing process with a temperature variation have performed by setting up heat bed temperature. After printing process was completed, the 3D scaffold was detained on the heat bed for 10 minutes before being picked up. The test results in this study had the lowest hardness value of 9.82±0.62 VHN and the highest number of 24.32±0.99 VHN. The compressive strength testing had the lowest value of 1.62±0.16 MPa with the highest number of 5.67±0.39 MPa. Pore observation using a scanning electron microscope. The result shows that the size of the pores were not much different, that was ±100-200 µm. This observation also indicated that the pore form was square pores.
Directory of Open Access Journals (Sweden)
Reinaldo Cesar
2017-06-01
Full Text Available Abstract Introduction Biomechanical assessment of trabecular bone microarchitecture contributes to the evaluation of fractures risk associated with osteoporosis and plays a crucial role in planning preventive strategies. One of the most widely clinical technics used for osteoporosis diagnosis by health professionals is bone dual-energy X-ray absorptiometry (DEXA. However, doubts about its accuracy motivate the introduction of congruent technical analysis such as calcaneal ultrasonometry (Quantitative Ultrasonometry - QUS. Methods Correlations between Bone Quality Index (BQI, determined by calcaneal ultrasonometry of thirty (30 individuals classified as normal, osteopenic and osteoporotic, and elastic modulus (E and ultimate compressive strength (UCS from axial compression tests of ninety (90 proof bodies from human vertebrae trabecular bone, which were extracted from cadavers in the twelfth thoracic region (T12, first and fourth lumbar (L1 and L4. Results Analysis of variance (ANOVA showed significant differences for E (p = 0.001, for UCS (p = 0.0001 and BQI. Spearman’s rank correlation coefficient (rho between BQI and E (r = 0.499 and BQI and UCS (r = 0.508 were moderate. Discussion Calcaneal ultrasonometry technique allowed a moderate estimate of bone mechanical strength and fracture risk associated with osteoporosis in human vertebrae.
Zingg, Sara; Anagnostou, Georg
2018-01-01
Non-uniform permeability may result in complex hydraulic head fields with potentially very high hydraulic gradients close to the tunnel face, which may be adverse for stability depending on the ground strength. Pore pressure relief by drainage measures in advance of the tunnel excavation improves stability, but the effectiveness of drainage boreholes may be low in the case of alternating aquifers and aquitards. This paper analyses the effects of hydraulic heterogeneity and advance drainage quantitatively by means of limit equilibrium computations that take account of the seepage forces acting upon the ground in the vicinity the tunnel face. The piezometric field is determined numerically by means of steady-state, three-dimensional seepage flow analyses considering the heterogeneous structure of the ground and a typical advance drainage scheme consisting of six axial boreholes drilled from the tunnel face. A suite of stability analyses was carried out covering a wide range of heterogeneity scales. The computational results show the effect of the orientation, thickness, location, number and permeability ratio of aquifers and aquitards and provide valuable indications about potentially critical situations, the effectiveness of advance drainage and the adequate arrangement of drainage boreholes. The paper shows that hydraulic heterogeneity results in highly variable face behaviour, even if the shear strength of the ground is constant along the alignment, but ground behaviour is considerably less variable in the presence of advance drainage measures.
Wang, Xiao; Wen, Zhijie; Jiang, Yujing; Huang, Hao
2018-03-01
The mechanical and acoustic emission characteristics of rock-like materials under non-uniform loads were investigated by means of a self-developed mining-induced stress testing system and acoustic emission monitoring system. In the experiments, the specimens were divided into three regions and different initial vertical stresses and stress loading rates were used to simulate different mining conditions. The mechanical and acoustic emission characteristics between regions were compared, and the effects of different initial vertical stresses and different stress loading rates were analysed. The results showed that the mechanical properties and acoustic emission characteristics of rock-like materials can be notably localized. When the initial vertical stress and stress loading rate are fixed, the peak strength of region B is approximately two times that of region A, and the maximum acoustic emission hit value of region A is approximately 1-2 times that of region B. The effects of the initial vertical stress and stress loading rate on the peck strain, maximum hit value, and occurrence time of the maximum hit are similar in that when either of the former increase, the latter all decrease. However, peck strength will increase with the increase in loading rate and decrease with the increase in initial vertical stress. The acoustic emission hits can be used to analyse the damage in rock material, but the number of acoustic emission hits cannot be used alone to determine the degree of rock damage directly.
Kim, Moon-Hwan; Oh, Jae-Seop
2015-01-01
[Purpose] The purpose of this study was to examine the effects of humeral head compression taping (HHCT) on the strength of the shoulder external rotator muscle in patients with rotator cuff tendinitis. [Subjects and Methods] Twenty patients with rotator cuff tendinitis were recruited. The shoulder external rotator strength was measured using a Biodex isokinetic dynamometer system. A paired t-test was performed to evaluate within-group differences in the strength of the shoulder external rota...
modified water-cement ratio law for compressive strength of rice
African Journals Online (AJOL)
user
various types of structures due to its structural stability and strength [1]. ... value of water-cement ratio results in greater pore spaces in .... as well as removing the excess water on the surface of the soil particles. ... and aggregate impact value.
Grimsley, Brian W.; Sutter, James K.; Burke, Eric R.; Dixon, Genevieve D.; Gyekenyesi, Thomas G.; Smeltzer, Stanley S.
2012-01-01
Several 1/16th-scale curved sandwich composite panel sections of a 10 m diameter barrel were fabricated to demonstrate the manufacturability of large-scale curved sections using minimum gauge, [+60/-60/0]s, toughened epoxy composite facesheets co-cured with low density (50 kilograms per cubic meters) aluminum honeycomb core. One of these panels was fabricated out of autoclave (OoA) by the vacuum bag oven (VBO) process using Cycom(Registered Trademark) T40-800b/5320-1 prepreg system while another panel with the same lay-up and dimensions was fabricated using the autoclave-cure, toughened epoxy prepreg system Cycom(Registered Trademark) IM7/977-3. The resulting 2.44 m x 2 m curved panels were investigated by non-destructive evaluation (NDE) at NASA Langley Research Center (NASA LaRC) to determine initial fabrication quality and then cut into smaller coupons for elevated temperature wet (ETW) mechanical property characterization. Mechanical property characterization of the sandwich coupons was conducted including edge-wise compression (EWC), and compression-after-impact (CAI) at conditions ranging from 25 C/dry to 150 C/wet. The details and results of this characterization effort are presented in this paper.
Nettles, A. T.; Scharber, L. L.
2017-01-01
This study measured the compression after impact strength of IM7 carbon fiber laminates made from epoxy resins with various mode I and mode II toughness values to observe the effects of these toughness values on the resistance to damage formation and subsequent residual compression strength-carrying capabilities. Both monolithic laminates and sandwich structure were evaluated. A total of seven different epoxy resin systems were used ranging in approximate GI values of 245-665 J/sq m and approximate GII values of 840-2275 J/sq m. The results for resistance to impact damage formation showed that there was a direct correlation between GII and the planar size of damage, as measured by thermography. Subsequent residual compression strength testing suggested that GI had no influence on the measured values and most of the difference in compression strength was directly related to the size of damage. Thus, delamination growth assumed as an opening type of failure mechanism does not appear to be responsible for loss of compression strength in the specimens examined in this study.
Prevention of Bridge Scour with Non-uniform Circular Piers Plane under Steady Flows
Chen, Hsing-Ting; Wang, Chuan-Yi
2017-04-01
River bed scour and deposit variation extremely severe because of most of rivers are steep and rapid flows, and river discharge extremely unstable and highly unsteady during different seasons in Taiwan. In addition to the obstruction of piers foundation, it causes local scour and threatens the safety of bridges. In the past, riprap, wire gabion or wrap pier works were adopted as the protections of piers foundation, but there were no effectual outcomes. The events of break off piers still happen sometimes. For example, typhoon Kalmaegi (2008) and Morakot (2009) caused heavy damages on Ho-Fon bridge in the Da-jia river and Shuang-Yuan bridge in the Kao-Ping river, respectively. Accordingly, to understand the piers scour system and propose an appropriate protection of piers foundation becomes an important topic for this study currently. This research improves the protection works of the existing uniform bridge pier (diameter D) to ensure the safety of the bridge. The non-uniform plane of circular piers (diameter D*) are placed on the top of a bridge pier foundation to reduce the down flow impacting energy and scour by its' surface roughness characteristics. This study utilize hydraulic models to simulate local scour depth and scour depth change with time for non-uniform pier diameter ratio D/D* of 0.3,0.4,0.5,0.6,0.7 and 0.8, and different type pier and initial bed level (Y) relative under the foundation top elevation under steady flows of V/Vc=0.95,0.80 and 0.65. The research results show that the scour depth increases with an increase of flow intensity (V/Vc) under different types of steady flow hydrographs. The scour depth decreases with increase of initial bed level (Y=+0.2D*,0D*and -0.2D*) relative under the foundation top elevation of the different type pier. The maximum scour depth occurred in the front of the pier for all conditions. Because of the scouring retardation by the non-uniform plane of foundation, the scour depth is reduced for the un-exposed bridge
Efficient SPECT scatter calculation in non-uniform media using correlated Monte Carlo simulation
International Nuclear Information System (INIS)
Beekman, F.J.
1999-01-01
Accurate simulation of scatter in projection data of single photon emission computed tomography (SPECT) is computationally extremely demanding for activity distribution in non-uniform dense media. This paper suggests how the computation time and memory requirements can be significantly reduced. First the scatter projection of a uniform dense object (P SDSE ) is calculated using a previously developed accurate and fast method which includes all orders of scatter (slab-derived scatter estimation), and then P SDSE is transformed towards the desired projection P which is based on the non-uniform object. The transform of P SDSE is based on two first-order Compton scatter Monte Carlo (MC) simulated projections. One is based on the uniform object (P u ) and the other on the object with non-uniformities (P ν ). P is estimated by P-tilde=P SDSE P ν /P u . A tremendous decrease in noise in P-tilde is achieved by tracking photon paths for P ν identical to those which were tracked for the calculation of P u and by using analytical rather than stochastic modelling of the collimator. The method was validated by comparing the results with standard MC-simulated scatter projections (P) of 99m Tc and 201 Tl point sources in a digital thorax phantom. After correction, excellent agreement was obtained between P-tilde and P. The total computation time required to calculate an accurate scatter projection of an extended distribution in a thorax phantom on a PC is a only few tens of seconds per projection, which makes the method attractive for application in accurate scatter correction in clinical SPECT. Furthermore, the method removes the need of excessive computer memory involved with previously proposed 3D model-based scatter correction methods. (author)
Experimental study on the CHF in uniformly and non-uniformly heated vertical annuli
Energy Technology Data Exchange (ETDEWEB)
Chun, Se Young; Moon, Sang Ki; Chung, Heung June; Park, Jong Kuk; Kim, Bok Deuk; Youn, Young Jung; Chung, Moon Ki
2001-09-01
Up to now, KAERI has performed critical heat flux experiments in water under zero-flow and low-flow conditions using a RCS CHF loop facility with uniformly and non-uniformly heated vertical annulus. Since the existing CHF experiments were mainly performed under low-pressure conditions, we performed the CHF experiment to investigate the pressure effect on the CHF under zero-flow and low-flow conditions for a wide range of system pressures. Also, two vertical annuli with the same geometry have been used to investigate the axial heat flux distributions on the CHF. This report summarizes the experimental results and provides the CHF data that can be used for the development for CHF correlation and a thermal hydraulic analysis code. The CHF data have been collected for system pressures ranging from 0.57 to 15.15 MPa, mass flux 0 and from 200 to 650 kg/m2s, inlet subcooling from 75 to 360 kJ/kg and exit quality from 0.07 to 0.57. At low-flow conditions, the total number of data are 242 and 290 with uniformly heated- and non-uniformly heated test sections, respectively. 41 and 94 CHF data are generated with uniformly heated- and non-uniformly heated test sections, respectively, in zero-flow CHF experiments that are performed by blocking test section bottoms. The CHF experiment result shows that the effects of system pressure, mass flux and inlet subcooling are consistent with conventional understandings and similar to those for round tubes. The behavior of the CHF is relatively complex at low pressures. Also, the effects of axial heat flux profile are large at low-pressure conditions.
Experimental study on the CHF in uniformly and non-uniformly heated vertical annuli
International Nuclear Information System (INIS)
Chun, Se Young; Moon, Sang Ki; Chung, Heung June; Park, Jong Kuk; Kim, Bok Deuk; Youn, Young Jung; Chung, Moon Ki
2001-09-01
Up to now, KAERI has performed critical heat flux experiments in water under zero-flow and low-flow conditions using a RCS CHF loop facility with uniformly and non-uniformly heated vertical annulus. Since the existing CHF experiments were mainly performed under low-pressure conditions, we performed the CHF experiment to investigate the pressure effect on the CHF under zero-flow and low-flow conditions for a wide range of system pressures. Also, two vertical annuli with the same geometry have been used to investigate the axial heat flux distributions on the CHF. This report summarizes the experimental results and provides the CHF data that can be used for the development for CHF correlation and a thermal hydraulic analysis code. The CHF data have been collected for system pressures ranging from 0.57 to 15.15 MPa, mass flux 0 and from 200 to 650 kg/m2s, inlet subcooling from 75 to 360 kJ/kg and exit quality from 0.07 to 0.57. At low-flow conditions, the total number of data are 242 and 290 with uniformly heated- and non-uniformly heated test sections, respectively. 41 and 94 CHF data are generated with uniformly heated- and non-uniformly heated test sections, respectively, in zero-flow CHF experiments that are performed by blocking test section bottoms. The CHF experiment result shows that the effects of system pressure, mass flux and inlet subcooling are consistent with conventional understandings and similar to those for round tubes. The behavior of the CHF is relatively complex at low pressures. Also, the effects of axial heat flux profile are large at low-pressure conditions
Directory of Open Access Journals (Sweden)
Sutrisno Wahyuniarsih
2017-01-01
Full Text Available Uniform corrosion still widely used by a lot of researchers and engineers to analyze the corrosion induced cracking. However, in practice, corrosion process occurred non-uniformly. The part nearest to the exposed surface is more likely to have faster corrosion initiation compared with other regions. This research is mainly focused on investigating the effect of non-uniform rust distribution to cover cracking in reinforced concrete. An experimental test performed using accelerated corrosion test by using 5% NaCl solution and applied a constant electric current to the concrete samples. The rust distribution and measurement were observed by using a digital microscope. Based on the experimental result, it was found that the rust was distributed in a non-uniform pattern. As a result, the cracks also formed non-uniformly along the perimeter of steel bar. At the last part of this paper, a simulation result of concrete cracking induced by non-uniform corrosion is presented. The result compared with a simulation using uniform corrosion assumption to investigate the damage pattern of each model. The simulation result reveals stress evolution due to rust expansion which leads to concrete cracking. Furthermore, a comparison of stresses induced by non-uniform corrosion and uniform corrosion indicates that non-uniform corrosion could lead to earlier damage to the structure which is specified by the formation and propagation of the crack.
Spall strength and ejecta production of gold under explosively driven shock wave compression
International Nuclear Information System (INIS)
La Lone, B. M.; Stevens, G. D.; Turley, W. D.; Veeser, L. R.; Holtkamp, D. B.
2013-01-01
Explosively driven shock wave experiments were conducted to characterize the spall strength and ejecta production of high-purity cast gold samples. The samples were from 0.75 to 1.84 mm thick and 30 mm in diameter. Peak stresses up to 44 GPa in gold were generated using PBX-9501 high explosive. Sample free surface and ejecta velocities were recorded using photonic Doppler velocimetry techniques. Lithium niobate pins were used to quantify the time dependence of the ejecta density and the total ejected mass. An optical framing camera for time-resolved imaging and a single-image x-ray radiograph were used for additional characterization. Free surface velocities exhibited a range of spall strengths from 1.7 to 2.4 GPa (mean: 2.0 ±0.3 GPa). The pullback signals were faint, minimal ringing was observed in the velocity records, and the spall layer continued to decelerate after first pull back. These results suggest finite tensile strength was present for some time after the initial void formation. Ejecta were observed for every sample with a roughened free surface, and the ejecta density increased with increased surface roughness, which was different in every experiment. The total ejected mass is consistent with the missing mass model.
The importance of non-uniform dose-distribution in an organ
International Nuclear Information System (INIS)
Richmond, C.R.
1975-01-01
The recent revival of interest in the 'hot particle' problem, especially as regards particulate plutonium and other actinide elements in the lung, stimulated the preparation of this paper. Non-uniformity of dose-distribution has been of concern to standards-setting bodies and other groups such as the National Academy of Sciences and to health protectionists for many years. This paper reviews data from animal experiments that are used by some to implicate particulate plutonium as being especially hazardous to man. Other relevant biological data are also discussed. (author)
Non-uniform absorption of terahertz radiation on superconducting hot electron bolometer microbridges
International Nuclear Information System (INIS)
Miao, W.; Zhang, W.; Zhong, J. Q.; Shi, S. C.; Delorme, Y.; Lefevre, R.; Feret, A.; Vacelet, T.
2014-01-01
We interpret the experimental observation of a frequency-dependence of superconducting hot electron bolometer (HEB) mixers by taking into account the non-uniform absorption of the terahertz radiation on the superconducting HEB microbridge. The radiation absorption is assumed to be proportional to the local surface resistance of the HEB microbridge, which is computed using the Mattis-Bardeen theory. With this assumption the dc and mixing characteristics of a superconducting niobium-nitride (NbN) HEB device have been modeled at frequencies below and above the equilibrium gap frequency of the NbN film
The effect of non-uniform fuel rod temperatures on effective resonance integrals
International Nuclear Information System (INIS)
Reichel, A.
1961-06-01
The effective resonance integral for heterogeneous lattices can be reduced to the effective resonance integral for an equivalent homogeneous system with a fairly well defined error depending on lump size and geometry. This report investigates the effect of a radial parabolic temperature variation in cylindrical lumps on the equivalent homogeneous effective resonance integral. Also determined is the equivalent uniform temperature to be taken in the usual formulae to allow for non-uniform fuel rod temperature. This effective temperature is found to be T eff. = T s + 4/9 (T c - T s ) where T s and T c are the surface and central temperatures of the lump. (author)
Non-Uniform Free-Free Absorption in the GPS Radio Galaxy 0108+388
Marr, J M; Crawford, F
2001-01-01
We have observed the canonical gigahertz-peaked spectrum source 0108+388 with the VLBA at a range of frequencies above and below the spectral peak. The activity that dominates the radio emission from 0108+388, which is also classified as a Compact Symmetric Object, is thought to be less than 1000 years old. We present strong evidence that the spectral turnover in 0108+388 results from free-free absorption by non-uniform gas, possibly in the form of a disk in the central tens of parsecs.
A mechanical model of a non-uniform ionomeric polymer metal composite actuator
International Nuclear Information System (INIS)
Anton, Mart; Aabloo, Alvo; Punning, Andres; Kruusmaa, Maarja
2008-01-01
This paper describes a mechanical model of an IPMC (ionomeric polymer metal composite) actuator in a cantilever beam configuration. The main contribution of our model is that it gives the most detailed description reported so far of the quasistatic mechanical behaviour of the actuator with non-uniform bending at large deflections. We also investigate a case where part of an IPMC actuator is replaced with a rigid elongation and demonstrate that this configuration would make the actuator behave more linearly. The model is experimentally validated with MuscleSheet(TM) IPMCs, purchased from BioMimetics Inc
Energy Technology Data Exchange (ETDEWEB)
Alvarez-Nodarse, R [Departamento de Analisis Matematico, Universidad de Sevilla, Apdo. 1160, E-41080 Sevilla (Spain); Atakishiyev, N M [Instituto de Matematicas, UNAM, Apartado Postal 273-3, CP 62210 Cuernavaca, Morelos, Mexico (Germany); Costas-Santos, R S [Departamento de Matematicas, EPS, Universidad Carlos III de Madrid, Ave. Universidad 30, E-28911, Leganes, Madrid (Spain)
2005-01-07
We argue that one can factorize the difference equation of hypergeometric type on non-uniform lattices in the general case. It is shown that in the most cases of q-linear spectrum of the eigenvalues, this directly leads to the dynamical symmetry algebra su{sub q}(1, 1), whose generators are explicitly constructed in terms of the difference operators, obtained in the process of factorization. Thus all models with the q-linear spectrum (some of them, but not all, previously considered in a number of publications) can be treated in a unified form.
International Nuclear Information System (INIS)
Piquero, Gemma; Vargas-Balbuena, Javier
2004-01-01
We provide a simple theoretical study of beams non-uniformly polarized across their transverse sections which can be introduced in undergraduate optics courses. In order to generate such beams we propose to use a slightly convergent (or divergent) linearly and uniformly polarized beam impinging on an anisotropic uniaxial material with the beam propagation direction along the optic axis. Analytical expressions for the Jones vector, Stokes parameters, ellipticity and azimuth at each point of the transverse section, perpendicular to the propagation direction, are obtained at the output of this system. By means of these parameters a detailed description of the state of polarization across the transverse profile is given
A new correlation of non-uniformly heated round tube burnout data
International Nuclear Information System (INIS)
Kirby, G.J.
1966-07-01
A new correlation of non-uniformly heated round tube burnout data is presented. This fits the available data better than any previously published correlation - the root-mean-square deviation being 5.7% for all data at 1000 p.s.i.a. and the worst fit being to data at 2000 p.s.i.a. where the r.m.s. error is 6.6%. The correlation is used to investigate the effect of flux profile changes and no significant increase in burnout power is obtained by modifying the present chopped cosine distribution. (author)
The reliability of multistory buildings with the effect of non-uniform settlements of foundation
Al'Malul, Rafik; Gadzhuntsev, Michail
2018-03-01
The issue is the evaluation of reliability of construction considering the influence of the variation of the support settlement, which is changing during the lifetime of constructions due to the consolidation process of the ground. Recently, the specialists give special emphasis to the necessity to develop the methods for the estimation of reliability and durability of structures. The problem, the article considers, is the determination of the reliability of multistory buildings with non-uniform changing-in-time sediments caused by the consolidation process in soils. Failure of structures may occur before the draft reaches it`s stabilizing value, because of the violations of the conditions of normal use.
International Nuclear Information System (INIS)
Nosek, Štěpán; Kukačka, Libor; Jurčáková, Klára; Kellnerová, Radka; Jaňour, Zbyněk
2017-01-01
This paper presents an extension of our previous wind-tunnel study (Nosek et al., 2016) in which we highlighted the need for investigation of the removal mechanisms of traffic pollution from all openings of a 3D street canyon. The extension represents the pollution flux (turbulent and advective) measurements at the lateral openings of three different 3D street canyons for the winds perpendicular and oblique to the along-canyon axis. The pollution was simulated by emitting a passive gas (ethane) from a homogeneous ground-level line source positioned along the centreline of the investigated street canyons. The street canyons were formed by courtyard-type buildings of two different regular urban-array models. The first model has a uniform building roof height, while the second model has a non-uniform roof height along each building's wall. The mean flow and concentration fields at the canyons' lateral openings confirm the findings of other studies that the buildings' roof-height variability at the intersections plays an important role in the dispersion of the traffic pollutants within the canyons. For the perpendicular wind, the non-uniform roof-height canyon appreciably removes or entrains the pollutant through its lateral openings, contrary to the uniform canyon, where the pollutant was removed primarily through the top. The analysis of the turbulent mass transport revealed that the coherent flow structures of the lateral momentum transport correlate with the ventilation processes at the lateral openings of all studied canyons. These flow structures coincide at the same areas and hence simultaneously transport the pollutant in opposite directions. - Highlights: • The pollutant transport strongly depends on the roof-height arrangement. • The non-uniform canyons also remove the pollutants through their lateral openings. • The higher the upstream wall, the more pollutant is removed through the top. • The lateral coherent structures correlate
Laser investigation of the non-uniformity of fluorescent species in dental enamel
Tran, Stephanie U.; Ridge, Jeremy S.; Nelson, Leonard Y.; Seibel, Eric J.
In the present study, artificial type I and type II erosions were created on dental specimen using acetic acid and EDTA respectively. Specimens were prepared by etching extracted teeth samples in acid to varying degrees, after which the absolute fluorescence intensity ratio of the etched enamel relative to sound enamel was recorded for each specimen using 405 and 532 nm laser excitation. Results showed differences in the fluorescence ratio of etched to sound enamel for type I and II erosions. These findings suggest a non-uniform distribution of fluorescent species in the interprismatic region as compared to the prismatic region.
Directory of Open Access Journals (Sweden)
Y. Luna-Galiano
2016-09-01
Full Text Available The main contribution of this paper relates to the development of a systematic study involving a set of parameters which could potentially have an impact on geopolymer properties: curing temperature, type of activating solution, alkali metal in solution, incorporation of slag (Ca source and type of slag used. The microstructures, degrees of reaction, porosities and compressive strengths of geopolymers have been evaluated. Geopolymers prepared with soluble silicate presented a more compacted and closed structure, a larger amount of gel, lower porosity and greater compressive strength than those prepared with hydroxides. On the other hand, Na-geopolymers were more porous but more resistant than K-geopolymers. Although there is an inverse relation between degree of reaction and porosity, between compressive strength and porosity it is not always inversely proportional and could, in some cases, be masked by changes produced in other influencing parameters.
Urban, K.; Sicakova, A.
2017-10-01
The paper deals with the use of alternative powder additives (fly ash and fine fraction of recycled concrete) to improve the recycled concrete aggregate and this occurs directly in the concrete mixing process. Specific mixing process (triple mixing method) is applied as it is favourable for this goal. Results of compressive strength after 2 and 28 days of hardening are given. Generally, using powder additives for coating the coarse recycled concrete aggregate in the first stage of triple mixing resulted in decrease of compressive strength, comparing the cement. There is no very important difference between samples based on recycled concrete aggregate and those based on natural aggregate as far as the cement is used for coating. When using both the fly ash and recycled concrete powder, the kind of aggregate causes more significant differences in compressive strength, with the values of those based on the recycled concrete aggregate being worse.
Karolina, Rahmi; Panatap Simanjuntak, Murydrischy
2018-03-01
Self Compacting Concrete (SCC) is a technology which is developing today in which concrete solidifies by itself without using vibrator. Casting conventional concrete which has a lot of reinforcement bars sometimes finds difficulty in achieving optimal solidity. The method used to solve this problem is by using SCC technology. SCC was made by using filler, volcanic ash, and lime ash as the filling materials so that the concrete became more solid and hollow space could be filled up. The variation of using these two materials was 10%, 15%, 20%, and 25% of the cementitious mass and using 1% of superplasticizer from cementitious material. The supporting testing was done by using the test when the concrete was still fluid and when it was solid. Malleable concrete was tested by using EFNARC 2002 standard in slump flow test, v-funnel test, l-shaped box test, and j-ring test to obtain filling ability and passing ability. In this malleable lime concrete test, there was the decrease, compared with normal SCC concrete without adding volcanic ash and lime ash. Testing was also done in solid concrete in compressive strength, tensile strength, and concrete absorption. The result of the testing showed that the optimum tensile strength in Variation 1, without volcanic ash and lime ash – with 1% of superplasticizer was 39.556 MPa, the optimum tensile strength in Variation 1, without volcanic ash and lime ash- with 1% of super-plasticizer was 3.563 MPa, while the value of optimum absorption which occurred in Variation 5 (25% of volcanic ash + 25% of lime ash + 50% of cement + 1% of superplasticizer) was 1.313%. This was caused by the addition of volcanic ash and lime ash which had high water absorption.
Baek, Jin Woong; Choi, Angelo Earvin Sy; Park, Hung Suck
2017-12-01
Optimization studies of a novel and eco-friendly construction material, Thiomer, was investigated in the solidification/stabilization of automobile shredded residue (ASR) fly ash. A D-optimal mixture design was used to evaluate and optimize maximum compressive strength and heavy metals leaching by varying Thiomer (20-40wt%), ASR fly ash (30-50wt%) and sand (20-40wt%). The analysis of variance was utilized to determine the level of significance of each process parameters and interactions. The microstructure of the solidified materials was taken from a field emission-scanning electron microscopy and energy dispersive X-ray spectroscopy that confirmed successful Thiomer solidified ASR fly ash due to reduced pores and gaps in comparison with an untreated ASR fly ash. The X-ray diffraction detected the enclosed materials on the ASR fly ash primarily contained sulfur associated crystalline complexes. Results indicated the optimal conditions of 30wt% Thiomer, 30wt% ASR fly ash and 40wt% sand reached a compressive strength of 54.9MPa. For the optimum results in heavy metals leaching, 0.0078mg/LPb, 0.0260mg/L Cr, 0.0007mg/LCd, 0.0020mg/L Cu, 0.1027mg/L Fe, 0.0046mg/L Ni and 0.0920mg/L Zn were leached out, being environmentally safe due to being substantially lower than the Korean standard leaching requirements. The results also showed that Thiomer has superiority over the commonly used Portland cement asa binding material which confirmed its potential usage as an innovative approach to simultaneously synthesize durable concrete and satisfactorily pass strict environmental regulations by heavy metals leaching. Copyright © 2017 Elsevier Ltd. All rights reserved.
Filippov, Alexander E; Gorb, Stanislav N
2015-02-06
One of the important problems appearing in experimental realizations of artificial adhesives inspired by gecko foot hair is so-called clusterization. If an artificially produced structure is flexible enough to allow efficient contact with natural rough surfaces, after a few attachment-detachment cycles, the fibres of the structure tend to adhere one to another and form clusters. Normally, such clusters are much larger than original fibres and, because they are less flexible, form much worse adhesive contacts especially with the rough surfaces. Main problem here is that the forces responsible for the clusterization are the same intermolecular forces which attract fibres to fractal surface of the substrate. However, arrays of real gecko setae are much less susceptible to this problem. One of the possible reasons for this is that ends of the seta have more sophisticated non-uniformly distributed three-dimensional structure than that of existing artificial systems. In this paper, we simulated three-dimensional spatial geometry of non-uniformly distributed branches of nanofibres of the setal tip numerically, studied its attachment-detachment dynamics and discussed its advantages versus uniformly distributed geometry.
Adding muscle where you need it: non-uniform hypertrophy patterns in elite sprinters.
Handsfield, G G; Knaus, K R; Fiorentino, N M; Meyer, C H; Hart, J M; Blemker, S S
2017-10-01
Sprint runners achieve much higher gait velocities and accelerations than average humans, due in part to large forces generated by their lower limb muscles. Various factors have been explored in the past to understand sprint biomechanics, but the distribution of muscle volumes in the lower limb has not been investigated in elite sprinters. In this study, we used non-Cartesian MRI to determine muscle sizes in vivo in a group of 15 NCAA Division I sprinters. Normalizing muscle sizes by body size, we compared sprinter muscles to non-sprinter muscles, calculated Z-scores to determine non-uniformly large muscles in sprinters, assessed bilateral symmetry, and assessed gender differences in sprinters' muscles. While limb musculature per height-mass was 22% greater in sprinters than in non-sprinters, individual muscles were not all uniformly larger. Hip- and knee-crossing muscles were significantly larger among sprinters (mean difference: 30%, range: 19-54%) but only one ankle-crossing muscle was significantly larger (tibialis posterior, 28%). Population-wide asymmetry was not significant in the sprint population but individual muscle asymmetries exceeded 15%. Gender differences in normalized muscle sizes were not significant. The results of this study suggest that non-uniform hypertrophy patterns, particularly large hip and knee flexors and extensors, are advantageous for fast sprinting. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Sutherland, B. R.
2016-02-01
It is well established that two-dimensional internal plane waves and modes in uniformly stratified fluid efficiently transfer energy to smaller scale waves and ultimately turbulent mixing through parametric subharmonic instability (PSI). The numerical simulations of MacKinnon & Winters (GRL 2005) predicted PSI should act efficiently to disrupt the internal tide. However, while in situ observations showed the presence of PSI, it was not found to be appreciable. One reason for the discrepancy between simulations and observations is that the former examined an internal mode in uniformly stratified fluid whereas, in reality, the internal tide exists in non-uniform stratification and is manifest as sinusoidal oscillations of the thermocline. Through theory supported by numerical simulations, it is shown that internal modes in non-uniform stratification immediately excite superharmonics, not subharmonic disturbances. These have double the horizontal wavenumber and double the frequency of the parent mode and hence move with the same horizontal phase speed of the parent mode. As the disturbances grow in amplitude, however, they interact with the parent mode generating small-scale vertically propagating internal waves within the strongly stratified layer. The occurrence of PSI over very long times can occur, as in the simulations of Hazewinkel and Winters (JPO 2011). However, a comprehensive understanding of the energy cascade from the internal tide to small scales must consider the evolution of excited superharmonic disturbances.
Non-Uniform Laser Surface Texturing of an Un-Tapered Square Pad for Tribological Applications
Directory of Open Access Journals (Sweden)
Antonio Ancona
2017-10-01
Full Text Available Femtosecond laser surface micro-texturing has emerged as a promising technology to enhance the tribological properties of different kinds of electromechanical devices. In this research paper, we have exploited the intrinsic flexibility and micrometric accuracy of femtosecond laser ablation to realize complex micro-structural modifications on the surface of a laboratory prototype of a steel thrust bearing (un-tapered pad. The Bruggeman Texture Hydrodynamics theory (BTH is employed for the design of the anisotropic and non-uniform texture maximizing the thrust load of the pad prototype. The preliminary experimental results, reported in this work, show that the non-uniform micro-texture largely affects the friction characteristics of the contact. In particular, in agreement with the BTH predictions, the tribo-system shows friction properties that are strongly sensitive to the direction of the sliding speed, as a consequence of the micro-fluid dynamics which are designed to occur only in a specific sliding direction. We suggest that the joint action of virtual prototyping (BTH lubrication theory and ultrafast laser micro-prototyping can lead to unconventional and impressive results in terms of enhanced or tailored contact mechanics properties of the generic lubricated tribopair.
Measurement of fuel importance distribution in non-uniformly distributed fuel systems
International Nuclear Information System (INIS)
Yamane, Yoshihiro; Hirano, Yasushi; Yasui, Hazime; Izima, Kazunori; Shiroya, Seiji; Kobayashi, Keiji.
1995-01-01
A reactivity effect due to a spatial variation of nuclear fuel concentration is an important problem for nuclear criticality safety in a reprocessing plant. As a theory estimating this reactivity effect, the Goertzel and fuel importance theories are well known. It has been shown that the Goertzel's theory is valid in the range of our experiments based on measurements of reactivity effect and thermal neutron flux in non-uniformly distributed fuel systems. On the other hand, there have been no reports concerning systematic experimental studies on the flatness of fuel importance which is a more general index than the Goertzel's theory. It is derived from the perturbation theory that the fuel importance is proportional to the reactivity change resulting from a change of small amount of fuel mass. Using a uniform and three kinds of nonuniform fuel systems consisting of 93.2% enriched uranium plates and polyethylene plates, the fuel importance distributions were measured. As a result, it was found experimentally that the fuel importance distribution became flat, as its reactivity effect became large. Therefore it was concluded that the flatness of fuel importance distribution is the useful index for estimating reactivity effect of non-uniformly distributed fuel system. (author)
Gravitational Influences on Flame Propagation through Non-Uniform, Premixed Gas Systems
Miller, Fletcher J.; Easton, John; Ross, Howard D.; Marchese, Anthony; Perry, David; Kulis, Michael
2001-01-01
Flame propagation through non-uniformly premixed (or layered) gases has importance both in useful combustion systems and in unintentional fires. As summarized previously, non-uniform premixed gas combustion receives scant attention compared to the more usual limiting cases of diffusion or uniformly premixed flames, especially regarding the role gravity plays. This paper summarizes our progress on furthering the knowledge of layered combustion, in which a fuel concentration gradient exists normal to the direction of flame spread. We present experimental and numerical results for flame spread through propanol-air layers formed near the flash point temperature (25 C) or near the stoichiometric temperature (33 C). Both the model and experimental results show that the removal of gravity results in a faster spreading flame, by as much as 80% depending on conditions. This is exactly the opposite effect as that predicted by an earlier model reported. We also found that having a gallery lid results in faster flame spread, an effect more pronounced at normal gravity, demonstrating the importance of enclosure geometry. Also reported here is the beginning of our spectroscopic measurements of fuel vapor.
Le Roux, J. A.; Arthur, A. D.
2017-09-01
Time-dependent solar energetic particle (SEP) acceleration is investigated at a fast, nearly parallel spherical traveling shock in the strongly non-uniform corona by solving the standard focused transport equation for SEPs and transport equations for parallel propagating Alfvén waves that form a set of coupled equations. This enables the modeling of self-excitation of Alfvén waves in the inertial range by SEPs ahead of the shock and its role in enhancing the efficiency of the diffusive shock acceleration (DSA) of SEPs in a self-regulatory fashion. Preliminary results suggest that, because of the highly non-uniform coronal conditions that the shock encounters, both DSA and wave excitation are highly time-dependent processes. Thus, DSA spectra of SEPs strongly deviate from the simple power-law prediction of standard steady-state DSA theory and initially strong wave excitation weakens rapidly. Consequently, the ability of DSA to produce high energy SEPs in the corona of ∼1 GeV, as observed in the strongest gradual SEP events, appears to be strongly curtailed at a fast nearly parallel shock, but further research is needed before final conclusions can be drawn.
International Nuclear Information System (INIS)
Soler, Rafael; Wheeler, Jeffrey M.; Chang, Hyung-Jun; Segurado, Javier; Michler, Johann; Llorca, Javier; Molina-Aldareguia, Jon M.
2014-01-01
Compression tests of 〈1 1 1〉-oriented LiF single-crystal micropillars 1–5 μm in diameter were carried out from 25 °C to 250 °C. While the flow stress at ambient temperature was independent of the micropillar diameter, a strong size effect developed with elevated temperature. This behavior was explained by rigorously accounting for the different contributions to the flow stress of the micropillars as a function of temperature and pillar diameter: the lattice resistance, the forest hardening; and the size-dependent contribution as a result of the operation of single-arm dislocation sources. This was possible because the micropillars were obtained by chemically etching away the surrounding matrix in directionally solidified LiF–NaCl and LiF–KCl eutectics, avoiding any use of focused ion beam methods, yielding micropillars with a controlled dislocation density, independent of the sample preparation technique. In particular, the role of the lattice resistance on the size effect of micrometer-size single crystals was demonstrated unambiguously for the first time. This result rationalizes the different values of power-law exponent for the size effect found in the literature for face-centered cubic and body-centered cubic metals as well as for covalent and ionic solids
Calibration of EBT2 film by the PDD method with scanner non-uniformity correction.
Chang, Liyun; Chui, Chen-Shou; Ding, Hueisch-Jy; Hwang, Ing-Ming; Ho, Sheng-Yow
2012-09-21
The EBT2 film together with a flatbed scanner is a convenient dosimetry QA tool for verification of clinical radiotherapy treatments. However, it suffers from a relatively high degree of uncertainty and a tedious film calibration process for every new lot of films, including cutting the films into several small pieces, exposing with different doses, restoring them back and selecting the proper region of interest (ROI) for each piece for curve fitting. In this work, we present a percentage depth dose (PDD) method that can accurately calibrate the EBT2 film together with the scanner non-uniformity correction and provide an easy way to perform film dosimetry. All films were scanned before and after the irradiation in one of the two homemade 2 mm thick acrylic frames (one portrait and the other landscape), which was located at a fixed position on the scan bed of an Epson 10 000XL scanner. After the pre-irradiated scan, the film was placed parallel to the beam central axis and sandwiched between six polystyrene plates (5 cm thick each), followed by irradiation of a 20 × 20 cm² 6 MV photon beam. Two different beams on times were used on two different films to deliver a dose to the film ranging from 32 to 320 cGy. After the post-irradiated scan, the net optical densities for a total of 235 points on the beam central axis on the films were auto-extracted and compared with the corresponding depth doses that were calculated through the measurement of a 0.6 cc farmer chamber and the related PDD table to perform the curve fitting. The portrait film location was selected for routine calibration, since the central beam axis on the film is parallel to the scanning direction, where non-uniformity correction is not needed (Ferreira et al 2009 Phys. Med. Biol. 54 1073-85). To perform the scanner non-uniformity calibration, the cross-beam profiles of the film were analysed by referencing the measured profiles from a Profiler™. Finally, to verify our method, the films were
Calibration of EBT2 film by the PDD method with scanner non-uniformity correction
International Nuclear Information System (INIS)
Chang Liyun; Ding, Hueisch-Jy; Chui, Chen-Shou; Hwang, Ing-Ming; Ho, Sheng-Yow
2012-01-01
The EBT2 film together with a flatbed scanner is a convenient dosimetry QA tool for verification of clinical radiotherapy treatments. However, it suffers from a relatively high degree of uncertainty and a tedious film calibration process for every new lot of films, including cutting the films into several small pieces, exposing with different doses, restoring them back and selecting the proper region of interest (ROI) for each piece for curve fitting. In this work, we present a percentage depth dose (PDD) method that can accurately calibrate the EBT2 film together with the scanner non-uniformity correction and provide an easy way to perform film dosimetry. All films were scanned before and after the irradiation in one of the two homemade 2 mm thick acrylic frames (one portrait and the other landscape), which was located at a fixed position on the scan bed of an Epson 10 000XL scanner. After the pre-irradiated scan, the film was placed parallel to the beam central axis and sandwiched between six polystyrene plates (5 cm thick each), followed by irradiation of a 20 × 20 cm 2 6 MV photon beam. Two different beams on times were used on two different films to deliver a dose to the film ranging from 32 to 320 cGy. After the post-irradiated scan, the net optical densities for a total of 235 points on the beam central axis on the films were auto-extracted and compared with the corresponding depth doses that were calculated through the measurement of a 0.6 cc farmer chamber and the related PDD table to perform the curve fitting. The portrait film location was selected for routine calibration, since the central beam axis on the film is parallel to the scanning direction, where non-uniformity correction is not needed (Ferreira et al 2009 Phys. Med. Biol. 54 1073–85). To perform the scanner non-uniformity calibration, the cross-beam profiles of the film were analysed by referencing the measured profiles from a Profiler™. Finally, to verify our method, the films were
National Research Council Canada - National Science Library
Elmstrom, Michael
2004-01-01
A computational fluid dynamic (CFD) investigation is presented that provides predictions of the aerodynamic impact of uniform and non-uniform coatings applied to the leading edge of a compressor airfoil in a cascade. Using a NACA 65(12...
International Nuclear Information System (INIS)
Majumdar, Bishnu; Patel, Narayan Prasad; Vijayan, V.
2006-01-01
The aim of this study is to derive the non-uniformity correction factor for the two therapy ionization chambers for the dose measurement near the brachytherapy source. The two ionization chambers of 0.6 cc and 0.1 cc volume were used. The measurement in air was performed for distances between 0.8 cm and 20 cm from the source in specially designed measurement jig. The non-uniformity correction factors were derived from the measured values. The experimentally derived factors were compared with the theoretically calculated non-uniformity correction factors and a close agreement was found between these two studies. The experimentally derived non-uniformity correction factor supports the anisotropic theory. (author)
Energy Technology Data Exchange (ETDEWEB)
Mellor, A.; Domenech-Garret, J.L.; Chemisana, D.; Rosell, J.I. [Departament de Medi Ambient i C.S., University of Lleida, Av. Alcalde Rovira Roure 191, E25198 (Spain)
2009-09-15
A two-dimensional finite element model of current flow in the front surface of a PV cell is presented. In order to validate this model we perform an experimental test. Later, particular attention is paid to the effects of non-uniform illumination in the finger direction which is typical in a linear concentrator system. Fill factor, open circuit voltage and efficiency are shown to decrease with increasing degree of non-uniform illumination. It is shown that these detrimental effects can be mitigated significantly by reoptimization of the number of front surface metallization fingers to suit the degree of non-uniformity. The behavior of current flow in the front surface of a cell operating at open circuit voltage under non-uniform illumination is discussed in detail. (author)
Directory of Open Access Journals (Sweden)
Aref Al-Swaidani
2017-01-01
Full Text Available Natural pozzolan is being widely used as cement replacement. Despite the economic, ecological, and technical benefits of its adding, it is often associated with shortcomings such as the need of moist-curing for longer time and a lower early strength. This study is an attempt to investigate the effect of adding limestone filler on the compressive strength and durability of mortars/concrete containing scoria. Sixteen types of binders with different replacement levels of scoria (0, 10, 20, and 30% and limestone (0, 5, 10, and 15% were prepared. The development of the compressive strength of mortar/concrete specimens was investigated after 2, 7, 28, and 90 days’ curing. In addition, the acid resistance of the 28 days’ cured mortars was evaluated after 90 days’ exposure to 5% H2SO4. Concrete permeability was also evaluated after 2, 7, 28, and 90 days’ curing. Test results revealed that there was an increase in the early-age compressive strength and a decrease in water penetration depths with adding limestone filler. Contrary to expectation, the best acid resistance to 5% H2SO4 solution was noted in the mortars containing 15% limestone. Based on the results obtained, an empirical equation was derived to predict the compressive strength of mortars.
Energy Technology Data Exchange (ETDEWEB)
Burak Felekoglu; Kamile Tosun; Bulent Baradan; Akin Altun; Bahadir Uyulgan [Dokuz Eylul University (Turkey). Faculty of Engineering
2006-09-15
Today, self-compacting mortars are preferred for repair purposes due to the application easiness and mechanical advantages. However, for self-compatibility, the paste phase must meet some certain criteria at fresh state. The cement as well as the ingredients of the paste, powders with cementitious, pozzolanic or inert nature and plasticizing chemical admixtures should be carefully chosen in order to obtain a suitable paste composition to enrich the granular skeleton of the mix. The physical properties of powders (shape, surface morphology, fineness, particle size distribution, particle packing) and physico-chemical (time-dependent hydration reactions, zeta potentials) interactions between cement powder and plasticizer should be taken into consideration. All these parameters affect the performance of fresh paste in different manners. There is no universally accepted agreement on the effect of these factors due to the complexity of combined action; thus, it is hard to make a generalization. This study deals with the selection of amount and type of powders from the viewpoint of fresh state rheology and mechanical performance. The influence of powder materials on self-compatibility, viscosity and strength were compared with a properly designed set of test methods (the mini-slump, V-funnel tests, viscosity measurements and compressive strength tests). It may be advised that, for each cement-powder-plasticizer mixture, a series of test methods can be used to determine the optimum content and type of materials for a specified workability.
Syazani Leman, Alif; Shahidan, Shahiron; Azmi, M. A. M.; Syamir Senin, Mohamad; Ali, N.; Abdullah, S. R.; Zuki, S. S. Mohd; Ibrahim, M. H. Wan; Nazri, Fadzli Mohamed
2017-11-01
Previous researches have shown that FRP are being introduce into wide variety of civil engineering applications. Fibre Reinforce Concrete (FRP) are also used as repairing method in concrete structures. FRP such as S-glass, AR-glass, E-glass, C-glass, and Aramid Fibre are the common material used in industry. The FRP strips provide the necessary longitudinal and hoop reinforcement. However, there are lots waste materials that can be form as fibre and used in repairing. Banner is a type of waste material fibre that can be used in repairing. In this study, banner will be used as the replacement of the common FRP. The confined concrete (cylinder) of 300mm height and 150mm diameter were cast with M35 grade concrete and tested until it is crack. Next banner are used as the wrapping along the cracking of the concrete with three different pattern that are full wrapping, two band wrapping and cross wrapping using epoxy. Epoxy is a common name for a type of strong adhesive used for sticking things together and covering surface. The objective of this study is to determine the maximum strength and the effect of different patterns wrapping of FRP (banner) on the compressive strength of confined concrete. The results are shows that banner are suitable as a replacement of material for FRP.
Directory of Open Access Journals (Sweden)
Hernández, E. F.
2016-03-01
Full Text Available This paper presents the mechanical performance and durability of concrete with water/cement (w/c ratios of 0.30 and 0.60 containing cactus mucilage and brown marine seaweed extract solutions (at 0.5° Brix concentrations. Cylindrical specimens (100 mm x 200 mm were cast and moist-cured for 0 and 28 days. Compressive strength, rapid chloride permeability, and chloride diffusion tests were conducted to evaluate all of the concrete mixes at the ages of 60 and 120 days. In addition, accelerated carbonation tests were carried out on specimens at the age of 180 days by exposure to 23 °C, 60% RH and at 4.4% CO2 for 120 days. The compressive strength results showed that only one concrete mix with admixtures increased in strength compared to the control. Regarding the rapid chloride permeability, chloride diffusion and carbonation, the results indicated that the durability of concretes containing organic additions was enhanced compared to the control.Este trabajo presenta el comportamiento mecánico y de durabilidad de concretos con relaciones agua/cemento de 0.30 y 0.60, conteniendo soluciones de mucílago de nopal y extracto de algas marinas cafés (0.5 °Brix de concentración. Especímenes cilíndricos (100 mm x 200 mm fueron elaborados y curados en húmedo por 0 y 28 días. Se evaluó la resistencia a la compresión, permeabilidad rápida y difusión de cloruros a los 60 y 120 días de edad. Adicionalmente, se realizaron pruebas de carbonatación acelerada en especímenes con 180 días de edad, expuestos a 23 °C, 60% HR y 4.4% de CO2 por 120 días. Los resultados de resistencia a la compresión muestran que únicamente una mezcla de concreto con adición orgánica incrementó su resistencia con respecto al control. Con respecto a la permeabilidad rápida a cloruros, difusión de cloruros y carbonatación, los resultados indican que la durabilidad de los concretos que contenían adiciones orgánicas fue mejorada con respecto al control.
Energy Technology Data Exchange (ETDEWEB)
Ohama, Y; Izumura, K [Nihon University, Tokyo (Japan). Collete of Engineering; Hayashi, S [Onoda Cement Co. Ltd., Yamaguchi (Japan)
1991-08-01
This paper discusses the preparation factors and curing conditions of superhigh-strength mortar, and explains a method of manufacturing superhigh-strength mortar having still higher strength and its superhigh strength generating mechanism. A recommended cement material for the superhigh-strength mortar is a Portland cement mixed with a high-purity silica at 20% and silica fume at 20%. This was made to a water-cement material ratio of 15% and fine aggregate cement material ratio of 1.06, cured in an autoclave, and further heat-cured at 200{degree}C for one day to obtain a superhigh-strength mortar. The compression and bending strengths reach 2,200 kgf/cm{sup 2} and 180 kgf/cm{sup 2} respectively when used with silica sand, and 3000 kgf/cm{sup 2} and 220 kgf/cm{sup 2} or more when used with stainless steel grits. The heat curing at 200{degree}C for a day increases remarkably the compression strength of the superhigh-strength mortar regardless of the curing conditions before the heat curing. 7 refs., 11 figs., 1 tab.
Bull, Daniel; Spearing, Simon; Sinclair, Ian
2015-01-01
This study applies mechanisms observed from previous work (the undamaged cone, toughness and extent of permanent out-of-plane deformation) to parametrically study their effects on residual compression after impact (CAI) strength using finite element models. Based on previous experimental work, tougher material systems exhibited up to 30% greater CAI strength for a given damage area. Based on this, it is necessary to understand what other parameters, beyond damage area, contribute to a loss in...