In this paper, a new kind of gripper is designed which passively conforms to the shape of an object. This universal gripper is proposed when some of the adaptability of a human hand is needed or situations where very different objects need to be gripped easily, reliably within rapid succession without any feedback. By adding an annular balloon around the Granular bag, a lateral force pushes the main membrane and increases the friction force between the bag and the load. According to the acquired test results reported in this paper, the modification on this new robotic gripping mechanism is effective and the the successful gripping is formulated. This new complete formulation can provide a good estimation for a successful gripper design.

The Material point method (MPM) is a numerical technique to modeling the large deformation and interaction between different phases of Materials. MPM combines the best aspects of both Lagrangian and Eulerian formulations while avoiding some shortcomings of them. In MPM a body is modeled with the particles which carry all physical properties of the continuum such as mass, momentum, strains and stresses. The background mesh is used to solving the momentum equation. In the first phase, information is mapped from particles to nodes. In the second phase, momentum equations are solved for the nodes, and then the updated nodes are mapped to the particles to updating their positions and velocities. In the third phase the grid is reset. In numerical simulation of Granular flows, large deformations and interactions between grain boundaries and buildings lead to the complexity in the structural behavior of the Material and, as a result, the complexity of the simulations. From different numerical techniques, the Material point method is a suitable method for simulating such problems. In this study, the problem of the collapse of a column of Granular Material on a rigid wall was simulated in two dimensions through Material point method. The surface profile and displacement of the front were compared with the laboratory results which a good accordance is observed between them. The results show that the ratio of the initial column plays an important role in the development of Granular mass.

Although a significant portion of conditions encountered in geotechnical engineering, for investigating engineering behavior of soil, involves unsaturated soils; the traditional analysis and design approach has been to assume the limiting conditions of soils being either completely dry or completely saturated. In unsaturated soils the capillary force produce attractive forces between particles. Discrete Element Method (DEM) is an appropriate tool to consider the capillary effects. The calculations performed in DEM is based on iterative application of Newton’s second law to the particles and force-displacement law at the contacts. In the present study, the behavior of unsaturated soils in pendular regime is simulated utilizing DEM. Triaxialcompression tests were modeled as two-dimensional, considering capillary force effects. Finally, capillary effects on Macro parameters of a simulated Granular soil (stress, axial strain, volumetric strain and void ratio) and Mohr Coulomb failure criteria parameters were studied.

Non-coaxiality plays a key role in modelling of problems with significant stress rotation in soil mechanics. This will be more crucial in types of soils or Granular Materials with anisotropy. Many of the constituent rocks of oil and gas reservoirs are of the anisotropic type, so considering anisotropy in the study of oil reservoirs will have special significance. Neglecting to account for stress and strain non-coaxiality would result in errors and overestimating soil capacity. A mathematical solution is developed and applied within the framework of multi-laminate model, to deal with this issue. Selecting multi-laminate frame as the base of the model facilitates consideration of anisotropy with less mathematical effort. In addition, tracing fabric evolution may be much easier in this framework. Concept of stress and strain vector fields are introduced for shear components of planes, and in contrast to ancestor multi-laminate models, shear stress is calculated through this concept for each plane in the proposed model. Using this method, non-coaxiality may be considered on planes, and consequently the integrated result of plane stresses will be non-coaxial as well. Finally, to apply the model for greater problems, a code is developed to introduce the new model to FE program, Opensees. The program is implemented for analyzing an experimental plane-strain loading test of an anisotropic dense specimen of Toyoura sand. The results show a good agreement between theory and experiment.

Throughout the present study, making use of sound created by wheat grain passing through a pipe, wheat flow rate was measured. The developed device consists of a hopper, metering device, sound sensor, delivery tube, DC motor as well as power supply. Several wheat mass flow rates were tested and the sound signals created through the passage of the grain through the discharge tube was measured and transferred to a computer using Data Acquisition Card (DAC). Utilizing MATLAB signal processing toolbox and wavelet transfer functions, it was possible to extract frequency characteristics of the sound signals used as the distinguishing features of the different flow rates. Artificial Neural Networks-Multilayer Perceptron (ANNMLP) and Discriminate Analysis (DA) were applied to classify different wheat flow rates. Results indicated that through an application of DA vs ANN-MLP it was possible to determine different wheat flow rates with respective accuracies of 97% and 89%.

Silos are structures used for storing different types of Granular Materials. Seismic behavior of reinforced concrete silos is very complex due to nonlinearity of reinforced concrete wall of silo and nonlinear behavior of Granular Material. In this paper, the effect of Granular Material-structure interaction is investigated for a reinforced concrete silo by using ABAQUS finite element package. A hypoplastic constitutive model is used for modeling the Granular Material. After modeling the Granular Material-structure interaction under seismic excitation, the results obtained are compared with those of models without Granular Material-structure interaction.

Silos are structures that are used for storing different types of Granular Material. Dynamic behavior of silos under seismic loads is very complex. In this paper seismic behavior of steel silos with different height to diameter ratios is investigated by considering Granular Material-structure interaction using ABAQUS finite element package. Silo wall is modeled by shell elements and its behavior is considered elastic, seismic behavior of Granular Material inside silo is highly nonlinear and requires a complex nonlinear description of the Granular Material. The hypo plasticity theory describes the stress rate as a function of stress, strain rate and void ratio. The Granular Material is modeled by solid elements and its behavior is considered with a hypo plastic constitutive model, for modeling of interaction between silo wall and Granular Material, surface to surface contact with coulomb friction law is considered between silo wall and Granular Material. The results show that the seismic behavior of silos is dependent on the height to diameter ratio of the silo and while considering a constant value for the distribution of acceleration in the height of silo leads to conservative design pressures for a squat silo based on Euro code 8, this assumption is not conservative for a slender silo.

Here, Discrete Element Method (DEM) has been used to study effects of vibration, created by a vibrator, on the outflow of silos. To ensure the simulations accuracy, sensitivity analysis was performed on the numerical solution factors. For validation, comparisons with the results available in the open literature have been made. Realistic conditions show that when the opening of the silo is not large enough, the silo becomes blocked. Here, by performing a number of simulations, the opening size threshold at which the silo becomes blocked was determined and named as the critical size. Numerical studies have been done for different values of the outlet size, vibration frequency and amplitude. Moreover, to find out effects of the vibrator location, relevant stimulations were conducted, and based on the obtained results, when its location was within 20% of the bottom height of the discharge funnel, it had the greatest effect. Furthermore, it was found that by increasing the vibration frequency, the impact of the vibrator increases however, the difference in the effects of different frequencies decreases with the increase of the vibration amplitude. In addition to the theoretical explanation, physical interpretation and reasoning has also been discussed.

Objective: Toxoplasmosis, caused by an intracellular protozoan parasite, and the Toxoplasma gondii, is widespread throughout the world. In recent years, significant progress has been made in the identification of vaccine candidates which could induce a protective response. GRA7, an excretory 29 kDa Toxoplasma gondii a dense Granular antigen released by infected host cells. In tachyzoite-infected cells, p29 accumulates within the parasitophorous vacuole and co-localizes with its delimiting membrane. Materials and Methods: In the present work, first genomic DNA of Toxoplasma gondii was extracted and used for amplifying of GRA7 gene as a template. Then PCR product was extracted from agarose gel and cloned into TOPO vector. The plasmid containing GRA7 gene was extracted from the transformed bacteria (TOP10 strain) and sequenced. Results: Sequence analysis of GRA7 gene cloned into TOPO vector showed only one base difference when composed with the gene bank sequence for RH strain was only one base. Conclusion: The results indicated that this clone is suitable for subcloning in Prokaryotic and Eukaryotic plasmid.

In the present study, discrete element method is used to simulate undrained two-dimensional behavior of polygonal particles in which, the cylinder method is used. By this method, pore pressure of the voids in a sample can be studied independently. In the cylinder method, it is assumed that there are channels among adjacent pores and the possibility of water exchange among the centers of the pores is provided. The pipes connect the adjacent pores center. Therefore, the pipe length is equal to the center distance of two adjacent pores. The diameter of all pipes is identical which represents the permeability of the soil. First, by using this method, the variations of average pore pressure versus deviatoric strain and pore pressure distribution contour in a sample with polygonal particles were compared with another study with elliptical particles that showed good conformity. The constant volume method was also used to simulate the undrained behavior of the sample and the results of both methods were compared. In the constant volume method, it is assumed that the sample volume stays constant during loading. The simulation was done for samples by two methods. These samples were subjected to confining pressure of 200 kPa and after consolidation, were loaded under deviatoric stress. The results showed that the output obtained by the cylinder method are in good agreement with the constant volume method and by increasing the stiffness of the water, the results of both methods containing the variations of the deviatoric stress and the pore pressure are closer to each other. In following, the undrained behavior was investigated by using cylinder method in terms of shear strength and pore water pressure in a sandy sample at the confining pressures of 200, 400, 800 and 1600 kPa. The Simulation results are in good agreement with laboratory results in such a way that more confining pressure, the shear strength and pore pressure are more positive, but by increasing confining pressure, the amount of pore pressure decreases in the specimen. The pore pressure distribution contour at the strains of 10% and 30% was presented by means of cylinder method and the effect of cylinder diameter changes on the pore pressure distribution contour was investigated. Investigating the pore pressure distribution contour at the strains of 10% and 30% showed that pore pressure in the sample center has the lowest value. The pore pressure in the sample pores closes by increasing the cylinder diameter, while the smaller the diameter of the cylinder, the greater the water pressure difference among the pores. At last, the effect of pore position on the pore pressure was studied. For this purpose, four positions were considered through the sample and the variations of the average pore pressure versus axial strain at three pipe diameters of 40, 200 and 450 micrometers were investigated. The results showed that the pressure of the whole sample pores get closer by increasing the pipe diameter. As the pipe diameter decreased, the pressure difference between the sample pores gets higher and this difference will be greater in the larger strains.