Strength measurement of rock requires testing that must be carried out on test specimens with particular sizes in order to fulfill testing standards or suggested methods. Often, the coring process breaks up the weaker core pieces, and they are too small to be used in either index tests or conventional strength tests such as point Load index (Is) and Brazilian tensile strength (BTS). One of the index tests to indirectly determine the rock strength is the block punch index (BPI) test, which requires flat disc specimens without special treatment. This study aimed to evaluate the applicability of the BPI test for predicting the uniaxial compressive strength (UCS), BTS and IS of the sandstones by empirical equations. Also, we have compared the performance of the BPI and IS for predicting the UCS and BTS. It was experimentally shown that BPI is a reliable method for predicting the UCS, BTS and Is of the sandstones under study. Moreover, the results indicate that BPI could be utilized with same importance as Is for predicting the UCS, while predicting the BTS by Is appears to be more reliable than BPI.

In this paper, a formulation is developed for obtaining the optimal trajectory of robot manipulators to maximize the Load carrying capacity for a given point-to-point task. The presented method is based on open loop optimal control. The indirect approach is employed to derive optimality conditions based on Pontryagin's Minimum Principle. The obtained necessary conditions for optimality lead to a two-point boundary-value problem solved via a multiple shooting method with the BVP4C command in MATLABâ Since the carrying payLoad is one of the system parameters, a computational algorithm is developed, which provides the capability of calculating the maximum payLoad for a point-to-point task. The main advantage of this method is obtaining various optimal trajectories with different maximum payLoads and path characteristics by changing the penalty matrices values. To demonstrate the efficiency of the proposed method and algorithm in obtaining the maximum payLoad trajectory, simulation is performed on a two-link manipulator.

This paper deals with the effect of lamination on the failure strength and fracture pattern of Upper Red Formation sandstones in southwest of Qom, Iran using Brazilian and point Load tests. For this purpose, six blocks were taken from a part of this formation and have been drilled at different directions of lamination planes such as 0°, 30°, 45°, 60° and 90°.Although, the selected sandstones are seems similar but, the carried out test results and their failure patternsare different. The tensile strength, point Load index and failure patterns in different inclination angles were determined for this group of sandstones. Also, the transitional angle of failurehas been determined for Brazilian and point Load tests. The test results clearly indicated that failure strength and fractures pattern of laminated sandstones is a function of lamination inclination angle. Also, the results show there is a good correlation between strength and failure pattern of this group of sandstones under Brazilian and point Load test conditions.

This paper presents the investigation of general formulation and numerical solution of the dynamic Load carrying capacity (DLCC) of flexible link manipulator. The proposed method is based on open loop optimal control problem. A two point boundary value problem (TPBVP) is taken from the Pontryagin's minimum principle. The indirect approach is employed to derive optimality conditions. The system’s dynamics equation of motion is obtained from Gibbs-Appell (G-A) formulation and assumed mode method (AMM). Elastic properties of the links are modeled according to the assumption of Timoshenko beam theory (TBT) and its associated mode shapes. As TBT is more accurate compared with the Euler-Bernoulli beam theory, it is utilized for mathematical modeling of flexible links. The main contribution of the paper is to calculate the maximum allowable Load of a flexible link robot while an optimal trajectory is provided. Finally, the result of the simulation and experimental platform are compared for a two-link flexible arm to verify the introduced technique. The efficiency of the proposed method is illustrated by performing some simulation studies on the IUST flexible link manipulator. Simulation and experimental results confirm the validity of the claimed capability for controlling point-to-point motion of the proposed method and its application toward DLCC calculation.

In this investigation, the impact of confining pressure on the tensile strength obtained by point Load test (PLT) is examined by particle flow code in two dimensions. In this regard, at first, a numerical model is calibrated using the Brazilian experimental test results. The tensile strength of the model material is equal to 2. 5 MPa. Secondly, PLT is performed on the numerical models with dimension of 15 cm × 50 cm. The rectangular models are tested by PLT under the presence of the confining pressure. The Loading rate is 0. 001 mm/min, confining that the pressure is changed with the 13 different values of 0 MPa, 0. 002 MPa, 1MPa, 1. 5 MPa, 2 MPa, 2. 5 MPa, 3MPa, 3. 5 MPa, 4 MPa, 5MPa, 6 MPa, 9 MPa, and 11 MPa. The results obtained show that the vertical tensile crack develops through the model under a low confining pressure, while several shear bands are developed in the models under a high confining pressure. The number of shear cracks is augmented by augmenting the confining pressure. Is(50) is the augment by augmenting the confining pressure. Also a new criterion is rendered in order to determine Is(50) based on the confining pressure.

Background and Aim: It is believed that a period of healing, approximately 3-4 months for mandible and 4-6 months for maxilla, are required to ensure osseointegration. Recently, a new method called Immediate Loading of implants have been proposed. This method provides improved stability of the implant by the immediate support of an iterim prosthesis. The aim of this study was to evaluate the success rate of the Immediate Loading single OPILS dental implants.Materials and Methods: Thirty-nine patients, including 26 females and 13 males, at the minimum age of 18 and maximum age of 54 years old, received 48 OPILS dental implants. In this prospective study, all samples were non-smoking, without any systemic disease or psychological problem. In all cases, and acrylic prefabricated crown was placed immediately after implant surgery. The definitive metal-ceramic crown was placed 2.5 months later in mandible and 5.5 months later in maxillae. Lack of pain, pus, implant immobility and less than 1mm bone loss were criteria of success.Results: The oral hygiene of females were better than males, 26 women had plaque index (0) and 11 of them had plaque index (1) where as out of 13 male subjects, 4 had plaque index (0), 6 had plaque index (2) and (3) had plaque index (3). The mean vertical bone loss, on mesial and distal parts, were less than 1mm, with the min. of 0 and max. of 0.4mm and the average of 0.2mm. All implants pass the defined criteria of success.Conclusion: On the basis of this short-term study, in single tooth cases, OPILS implants of Neo-Dent system can be Loaded immediately.