A higher order control volume based finite element method to prodict the deformation of heterogeneous materials

Materials with obvious internal structure can exhibit behaviour, under loading, that cannot be described by classical elasticity. It is therefore important to develop computational tools incorporating appropriate constitutive theories that can capture their unconventional behaviour. One such theory is micropolar elasticity. This paper presents a linear strain control volume finite element formulation incorporating micropolar elasticity. Verification results from a micropolar element patch test as well as convergence results for a stress concentration problem are included. The element will be shown to pass the patch test and also exhibit accuracy that is at least equivalent to its finite element counterpart

The influence of void size on the micropolar constitutive properties of model heterogeneous materials

In this paper the mechanical behaviour of model heterogeneous materials consisting of regular periodic arrays of circular voids within a polymeric matrix is investigated. Circular ring samples of the materials were fabricated by machining the voids into commercially available polymer sheet. Ring samples of differing sizes but similar geometries were loaded using mechanical testing equipment. Sample stiffness was found to depend on sample size with stiffness increasing as size reduced. The periodic nature of the void arrays also facilitated detailed finite element analysis of each sample. The results obtained by analysis substantiate the observed dependence of stiffness on size. Classical elasticity theory does not acknowledge this size effect but more generalized elasticity theories do predict it. Micropolar elasticity theory has therefore been used to interpret the sample stiffness data and identify constitutive properties. Modulus values for the model materials have been quantified. Values of two additional constitutive properties, the characteristic length and the coupling number, which are present within micropolar elasticity but absent from its classic counterpart have also been determined. The dependence of these additional properties on void size has been investigated and characteristic length values compared to the length scales inherent within the structure of the model materials

Effect of Platen Restraint on Stress–Strain Behavior of Concrete under Uniaxial Compression: A Comparative Study

The stress-strain model of concrete depends on the degree of frictional resistance across the loading surfaces of a test specimen depending on the antifriction medium used during testing. This article presents a comparative study of platen restraint on the behavior of concrete under uniaxial compression based on an experimental investigation. The effect of four commercially available antifriction media (neoprene, polyvinyl chloride, teflon, and grease) with different layer thicknesses on platen restraint have been studied for a normal strength concrete and a relatively high-strength concrete. Subsequently, the effect of platen restraint has been quantified using the analogy of toughness. The experimental results indicate that post-ultimate response of concrete is significantly affected by platen restraint. It is shown that the stress–strain curve obtained from a conventional uniaxial compression test not only describes specimen/material behavior but also represents interaction between specimen and loading platen. Among the four antifriction media used in this investigation, grease is the most effective in reducing frictional resistance. Failure patterns of the concrete specimens for different antifriction media are also subsequently analyzed

Is there a Consensus in the Management of Distal Radial Fractures?

This unique postal survey was setup to assess the agreement on treatment options in displaced distal radius fractures and whether or not there existed a consensus amongst the surgeons contacted. With this in view we contacted 244 surgeons and 166 completed answers were received

Stochastic approximation with series of delayed observations

The stochastic approximation procedure with series of delayed observations is investigated. The procedure is formed by modifying the Robbins–Monro stochastic approximation procedure to be applicable in the presence of series of delayed observations. The modified procedure depends on a new base concerning the relation between service time of the series and service times of its components. Two loss systems are introduced for application to the proposed procedure. This new situation can be applied to increase the production of items in many fields such as biological, medical, life time experiments, and some industrial projects, where items are realized after random time delays. The efficiency of the procedure is computed. Our proposal is general and we expect that it can be applied to any other stochastic approximation procedure

Impact of sowing interval on the yield and yield contributing traits of sesame (Sesamum indicum L.) under the tropical circumstance

The experiment was conducted to study the impact of sowing interval on the yield and yield contributing traits of sesame (Sesamum indicum L.), under the tropical circumstance, during 2016, at the research area present near Faculty of Agriculture, Lasbela University of Agriculture, Water and Marine Science, Uthal, Balochistan. Experimental treatments were comprising three varieties of sesame, SV1 (TS-5), SV2 (TH-6) and SV3 (4002), and cultivated under different three sowing dates, at 15 days interval: S1 = 1st sowing (15 March 2016), S2 = 2nd sowing (1st April 2016) and S3 =3rd sowing (15 April 2016). The results of various observations, i.e. plant height at maturity (cm), 1000-seed weight (g), seed mass (t ha-1), yield index (%) rooting depth (cm) and root weight per plant was found to be significant both for the all the sowing dates and sesame genotypes. Non significant finding was observed in traits of biological yield per plant (g) and root-shoot ratio. Whereas interaction among all the treatment factors was non-significant. Maximum yield and yields contributing parameters was observed in S3 = 3rd sowing (15 April 2016) and sesame genotype SV1 (TS-5), followed by SV2 (TH-6), while minimum yield was noted in S3 = 3rd sowing (15 April 2016) and SV3 (4002) sesame genotypes. On the basis of the coastal agroclimatic condition of district Lasbela, it was concluded that maximum yield production was achieved from the sesame variety (TS-5), as compared to other two sesame (TH-6 and 4002) varieties. Sowing date of sesame at 15th April 2016 was more productive, as compared to the other sowing interval. Coastal climatic condition is feasible for sesame cultivation, especially for the sesame variety (TS-5)

Impact of Sowing Interval on the Yield and Yield Contributing Traits of Sesame (Sesamum indicum L.) under the Tropical Circumstance

The experiment was conducted to study the impact of sowing interval on the yield and yield contributing traits of sesame (Sesamum indicum L.), under the tropical circumstance, during 2016, at the research area present near Faculty of Agriculture, Lasbela University of Agriculture, Water and Marine Science, Uthal, Balochistan. Experimental treatments were comprising three varieties of sesame, SV1 (TS-5), SV2 (TH-6) and SV3 (4002), and cultivated under different three sowing dates, at 15 days interval: S1 = 1st sowing (15 March 2016), S2 = 2nd sowing (1st April 2016) and S3 =3rd sowing (15 April 2016). The results of various observations, i.e. plant height at maturity (cm), 1000-seed weight (g), seed mass (t ha-1), yield index (%) rooting depth (cm) and root weight per plant was found to be significant both for the all the sowing dates and sesame genotypes. Non significant finding was observed in traits of biological yield per plant (g) and root-shoot ratio. Whereas interaction among all the treatment factors was non-significant. Maximum yield and yields contributing parameters was observed in S3 = 3rd sowing (15 April 2016) and sesame genotype SV1 (TS-5), followed by SV2 (TH-6), while minimum yield was noted in S3 = 3rd sowing (15 April 2016) and SV3 (4002) sesame genotypes. On the basis of the coastal agroclimatic condition of district Lasbela, it was concluded that maximum yield production was achieved from the sesame variety (TS-5), as compared to other two sesame (TH-6 and 4002) varieties. Sowing date of sesame at 15th April 2016 was more productive, as compared to the other sowing interval. Coastal climatic condition is feasible for sesame cultivation, especially for the sesame variety (TS-5)

Modeling of an isothermal flow of a magnetohydrodynamic, viscoplastic fluid during forward roll coating process

An isothermal and incompressible flow of a magnetohydrodynamici (MHD) viscoplastic fluid has been examined while passing through the area among two co-rotating rolls. Applying lubrication approximation theory (LAT), the basic flow equations of mass and momentum are derived and subsequently non-dimensionalized. Exact solutions of velocity and pressure gradient distributions are evaluated. To evaluate the complex integrals, Trapezoidal rule for numerical integration is used. The significant engineering parameters like, the roll separation force, maximum pressure and the power transferred to the fluid by the rolls, are also numerically computed. The results demonstrate that the velocity field and pressure gradient are significantly affected due to the presence of the viscoplastic parameter. Magnetic field is found to be the controlling parameter for power input, separating force, and distance among attachment and detachment points, being extremely beneficial for the roll coating process. It has been learnt through this study that MHD can be an effective tool in the coating industry to regulate the engineering quantities in which coating thickness is the most important

Dechlorane Plus as an emerging environmental pollutant in Asia: A review

Dechlorane Plus (DP) is an unregulated, highly chlorinated flame retardant. It has been manufactured from past 40 years but its presence in the environment was initially reported in 2006. Later, it has been found in various biotic and abiotic environmental matrices. However, little attention has been paid to monitor its presence in Asia. Many studies have reported the occurrence of DP in the environment of Asia, yet the data are scarce, and studies are limited to few regions. The objective of present review is to summarize the occurrence, distribution, and toxicity of this ubiquitous pollutant in various environmental matrices (biotic and abiotic). DP has also been reported in the areas with no emission sources, which proves its long-range transport. Moreover, urbanization and industrialization also affect the distribution of DP, i.e., high levels of DP have been found in urban areas relative to the rural. Tidal movement also incorporates in transport of DP across the aquatic system. Further, bioaccumulation trend of DP in various tissues is kidney > liver > muscle tissues, whereas, blood brain barrier resists its accumulation in brain tissues. Additionally, gender-based accumulation trends revealed high DP levels in females in comparison to males due to strong metabolism of males. Furthermore, methodological aspects and instrumental analysis used in previous studies have also been summarized here. However, data on biomagnification in aquatic ecosystem and bioaccumulation of DP in terrestrial food web are still scarce. Toxicity behavior of syn-DP and anti-DP is still unknown which might gain the interest for future studies