In civil and mining, the design of some structures, such as pillars in mines and bridges, requires the knowledge of the effect of the relative size of dimensions (shape effect) on the strength of the structure. Therefore, to assess the effect of shape on the uni-AXIAL strength of rocks, laboratory tests were conducted on samples of 3 different types of rocks (namely; Isfahan dolomite, Bookan limestone and Gadouk sandstone) with various sample relative dimensions. Analyzing the data of these tests resulted in an overall relationship as σc =k σc√ D/L where D, L and σC1  are the diameter, length and the uni-AXIAL compressive strength of a sample with D/L=1 and K was obtained to be 1.14, 1.21 and 0.96 for the 3 rock types relatively. Also, as D/L and confining pressure affect uni-AXIAL compressive strength and TRI-AXIAL compressive strength similarly, 3 AXIAL tests, in various confining pressures, were conducted on the samples of the same rocks with D/L=0.5. Graphs of  σ -3σc and  σC - D/L were compared.  After omitting the term  σC from these formulas the overall relationship of ) σ3=A(D/L)-B was obtained. Finally, for the 3 type of rocks, a single formula as…σ3= 8.7515 D/L-6.3789 with coefficient of determination of 0.9534 was introduced. By applying the simulation proposed in this study, within the limit of the results, the costly time consuming TRI-AXIAL tests can be replaced with uni-AXIAL ones.

This article describes the details of a TRI-AXIAL Spacecraft Simulator Testbed (TSST) that has been developed as part of a research program on spacecraft multi-body rotational dynamics and control in Space Research Laboratory (SRL) at K. N. Toosi University of Technology. This dumbbell style simulator includes a variety of components: spherical air-bearing, inertial measurement unit (IMU), rechargeable battery, reaction wheels (RW), on-board computer (OBC) and balancing masses. In this paper, an attitude control problem for the spacecraft simulator actuated by three reaction wheels is studied. Under the assumption of uniform gravity and frictionless air-bearing environment, reaction wheels generate control moments about the roll, pitch and yaw axes of the base body. The control objective is to perform attitude commands sent from users with the least power consumption and a high precision. To handle the non-linear model, a Linear Quadratic Ricatti (LQR) controller has been programmed and it efficaciously controlled the computer-modeled simulator for any given slewing maneuver.This control approach has been developed to facilitate the system to accomplish largeangle, three-axis slewing maneuvers using RWs as effective actuators.

One of the main goals in the field of lab-on-a-chip is the manipulation of microparticles and cells on microfluidic chips. Methods based on magnetic forces, with remote controllability over particle movement, are considered one of the most appealing techniques toward this goal. Recently, inspired by electronic circuits and to transport particles in a controlled fashion in a TRI-AXIAL magnetic field, magnetophoretic circuits based on TI-shaped magnetic thin films are introduced. However, to date, capacitors are not used in order to store transported particles in these circuits. Here, TI magnetophoretic capacitors are introduced and characterized. The capability of the capacitor for storing particles of different sizes at various rotating magnetic field frequencies is studied. Towards this goal, finite element methods are used to simulate the magnetic potential energy disTRIbution created by the magnetic thin films. Also, the trajectory of the magnetic particles, considering the drag forces, based on semi-analytical analysis and statistical methods, is investigated. The simulation results are validated experimentally. At the operating frequency of 0.1 Hz loading efficiency of 98% was achieved. Adding this circuit element to the magnetophoretic circuits results in a complete chip, with important applications in lab-on-a-chip systems, single-cell biology, and drug screening.

Understanding the role and significance of the different components of the trunk neuro-musculo-skeletal system is of great importance for development of proper preventive and curative measures for low back pain. The experimental investigations, using lumbar moment measurement devices, are considered the most useful sources of information for detail understanding of the biomechanics of trunk and its components. This paper describes the conceptual design of a new lumbar moment measurement system, based on minimum deflection, anthropomeTRIc characteristics, and measurement considerations. The system is capable to measure the 3-D trunk moments using uni-directional torque sensors within a proper configuration of links and joints. Some other features of the system include convergence of its joints, high stability, and ability to adapt to a wide range of anatomical postures is standing and sitting positions.

The purpose of the present study is to evaluate mechanical {stress-strain and volumeTRIc} behavior of granular materials considering their internal physical properties in particle scale. To this end, two-dimensional numerical modeling of drained compressive TRI-AXIAL test, using Discrete Element Method (DEM) was utilized. DEM-2D computer code was adopted for modeling these tests based on Discrete Element Method formulation. Drained biAXIAL numerical tests on specimens with different void ratios and confining pressures were carried out and the results are compared with the associated laboratory tests results reported in the literature.

The object of the present work was to design, construct and evaluate a cylindrical TRI-AXIAL charger for charging of submicron aerosol particles by unipolar ions. The corona discharge characteristics, the inTRInsic and exTRInsic particle charging efficiencies, and the losses of aerosol particles were experimentally evaluated for particle diameters in the range between 50 nm and 500 nm under different operating conditions. The conditions included the corona voltages of about 7. 0 to 8. 0 kV, the mesh screen voltages of about 100 to 300 V and the aerosol flow rate was set at 1. 5 L/min. It was found that the ion current increased from 2. 90 10-10 to 3. 66 10-8 A and 2. 40 10-10 to 1. 36 10-7 A and the number concentration of ions increased from 7. 50 109 to 5. 92 1011 ions/m3 and 6. 21 109 to 2. 19 1012 ions/m3 when the corona voltage increased from 5. 5 to 8. 0 kV at the mesh screen voltage between 100 and 300 V, respectively. The inTRInsic charging efficiency of particles introduced a constant value of about 99% for particle diameter in the range between 50 nm and 200 nm and decreased with particle diameter in the range between about 300 nm and 500 nm at a given corona voltage. The best exTRInsic charging efficiency of the studied charger occurred between 1. 32% and 38% for particle diameter in the range from 50 nm to 500 nm at corona and ion trap voltages of about 7. 0 kV and 300 V respectively. The highest electrostatic loss of particles was observed at 50 nm particles and it was about 89. 08, 90. 73 and 91. 91% at a mesh screen voltage of about 300 V for corona voltages of about 7. 0, 7. 5 and 8. 0 kV, respectively. Finally, the highest diffusion losses were at about 28. 88, 23. 03 and 11. 15% for singly charged, neutralized and non-charged particles of 500, 500 and 50 nm, respectively.

In this paper, the energy absorption features of TRI-layer explosive-welded deep-drawn cups subjected to quasi-static AXIAL compressive loading are investigated numerically and experimentally. To produce the cups, TRI-layer blanks composed of aluminum and stainless steel alloys were fabricated by an explosive-welding process and formed by a deep drawing setup. The quasi-static tests were carried out at a rate of 2 mm/min. Based on the structure of the TRI-layer cups and to calculate the energy absorption features of these structures, a numerical model was established and validated by experimental findings. Moreover, based on a surrogate model and using non-domain sorting genetic algorithm II, multi-objective optimizations were performed on specific energy absorption and initial peak load. The results indicated that the total absorbed energy and mean crush force of the pure stainless steel TRI-layer cup were about 5. 8 and 5. 7 times the values of those for the pure aluminum specimen, respectively.

In this study, a series of laboratory tests using a real TRI-AXIAL Hydraulic Fracture System were performed to investigate the mechanism of fracture initiation and propagation on the cement blocks in different reservoirs in normal and tectonic stress regimes. The influences of crustal stress field, confining pressure, and natural fractures on the fracture initiation and propagation were discussed. Experimental results demonstrate that stress concentration around the hole would significantly increase the fracture pressure of the rock. At the same time, natural fractures in the borehole wall would eliminate the stress concentration, which leads to a decrease about two thirds in the fracture initiation pressure. Two interaction types between induced fractures with pre-fracture were observed including crossing and opening the pre-existing fracture. In a normal stress regime, hydraulic fracture crossed the pre-fracture. But in tectonically stressed or shallow reservoirs, due to high interaction between hydraulic and natural fractures, hydraulic fracture was arrested by opening of the pre-fracture.

In this study, a series of laboratory tests were conducted using a hydraulic fracturing system on the cement block specimens to investigate the hydraulic fracturing propagation and interaction with pre-existing fracture under true TRI-AXIAL stresses regime. The pre-existing fracture was prepared with different dip and sTRIke angles in the test blocks. The Experimental results demonstrated two basic types of hydraulic fracture propagation in interaction point with pre-existing fracture, crossing and no crossing modes. They can be clearly identified from the relationships among sTRIke angle, dip angle and in situ stresses. Two empirical relationships were proposed to describe the interactions between the pre-existing and hydraulic fractures. These relationships can be useful to predict the hydraulic fracture propagation behavior in naturally fractured reservoirs, although its accurate determination requires the more experimental and theoretical studies.