Sharif Digital Repository

Background: Secure grasping and effective manipulation of delicate large organs during robotic surgery operations needs especially designed instruments that can enclose a large amount of tissue and feed back the pinch forces. Methods: A large organ triple-jaw grasper was instrumented using practical force sensory and actuating systems. A force tracking scheme was proposed to facilitate auto-grasping of large organs during robotic teleoperation surgery. An on-site force commanding/reflecting mechanism was also implemented to use the device as an independent hand-held robotic instrument. The efficacy of the robotic grasper was examined in phantom tests. Results: The instrument grasped large... 

The currently available laparoscopic instruments are unable to manipulate and grasp the large intra-abdominal organs, such as spleen and kidney, with sufficient stability and safety. This paper describes a novel three-fingered endoscopic instrument, based on parallelogram mechanism, which can fully constrain the large organs and provide an effective grasping function. We first evaluated the efficacy of the design using a 3D model and finite element analysis. Then, a fully functional prototype was fabricated for experimental evaluations, including force propagation and pull force limitation characteristics. Finally, the instrument's capability for effective grasping was investigated on animal... 

During laparoscopic surgery, grasping of large body organs such as spleen, kidney, and liver, is a difficult task using conventional instruments. This paper describes the design and analysis of a novel actuated endoscopic grasper for manipulation of large internal organs. The designed instrument resembles a miniaturized three fingered hand with each finger consisting of two links. It could pass through a 10 mm trocar and then be opened inside the abdomen to grasp body organs up to 80 mm diameter. A detailed force analysis of the mechanism revealed that high actuating forces are required to grasp large organs. In order to facilitate the actuation of the grasper, its dimensions were optimized... 

This study conceptualizes the consumers' engagement with social media activation campaigns, which are important tools in improving the interactions between brands and consumers. We offer a comprehensive definition of this construct and discuss the nature and dimensionality of it. Further, this paper reports the development and validation of a 12-item scale for measuring the aforementioned construct. This scale development process comprises four studies. Study 1 begins by generating a pool of items and then employs both a panel of experts and some Instagram users to examine the content validity of the items. To validate the scale, this paper carries out several online surveys in subsequent... 

In this investigation, the permeability of interdendritic liquid flow through the equiaxial mushy zone has been modelled for Pb-Sn alloys based on experimental measurements. In the present work by solving Navier-Stokes equation, the flow pattern around the equiaxed dendrite has been obtained and then permeability has been determined by applying Darcy's law. Numerical determined values of permeabilities have been analysed by the use of Statistical Package for the Social Sciences (SPSS) statistical software. Then an experimental method has been used to measure the permeability for flow through equiaxial mushy zone of Pb-Sn alloys. Results show that increasing the solid fraction and... 

Exploring the effects of advertisement on attitude toward a brand has been a major concern to marketing scholars for decades. However, the literature on brand attitudes is so broad and the areas of focus of researchers are so fragmented that cognitive and affective elements and processes involved are often studied in isolation, neglecting the joint effects of these variables and resulting in a disconnected literature. In this paper, an integrative model of determinants and moderators of attitude toward the brand is provided along with a brief literature review of its formation and change. Key features of the model are: 1) comprehensive discussions on antecedents and moderators of brand... 

A numerical model has been developed for the determination of liquid flow permeability through columnar dendrite during growth and segregation in Al-Si mushy alloys. The model is inclusive of two stages, first numerical evolution of the dendrite shape during growth, and second numerical determination of the permeability. Simulation results shown which Si concentration by transform of dendrite shape dendrite could reduce of the interdendritic liquid permeability. © 2005 Elsevier Ltd. All rights reserved  

Vibration measurement is an important tool in many research fields; there are several methods for measuring vibration of a system. In conventional methods accelerometers are fixed to the body, so there is a systemic error due to fixing an external object to the body surface that interferes with the true vibration of the body. We have proposed image processing as a new method to record and determine the frequency response of human body. This method provides vibration measuring without using contacting sensors. Moreover the main advantage is its lower noise sensitivity in comparison to accelerometers. Further more another important point is the fact that all devices used in our developed... 

A vast amount of death in the world has been attributed to atherosclerosis. This disease causes plaque formation and finally lack of blood supply to an organ. The prominent aim of this study is proposing an accurate and simple model to investigate the process of arterial wall thickening. In order to investigate LDL (low density lipoprotein) accumulation in arterial wall which is considered the first stage of atherosclerosis, a four layer model for arterial wall consisting of endothelium, intima, IEL and media is presented. All layers are treated as homogenous porous media. The four-layer arterial wall model is the most powerful and reliable tool for modeling LDL transport within arterial... 

A robotic system was designed and developed to perform the camera handling task during laparoscopic surgery. The system employs an effective low cost mechanism, with a minimum number of actuated DOFs, enabling spherical movement around a remote centre of motion positioned at the the insertion point of the laparoscopic stem. Kinematic analysis showed a high manipulability measure for the system, with the left/right movements directly governed by rotation of the first rotary actuator, and zoom and up/down movements by the simultaneous motions of the linear and second rotary actuators. A prototype of the robot was developed for practical use in an operating room environment. Hands-free operator... 

Various urban, industrial, and agricultural pollutions discharge more than river self-purification potential damages river ecosystem and increases water treatment costs. As different decision-makers and stakeholders are involved in the water quality management in river systems, a new bankruptcy form of the game theory is used to resolve the existing conflict of interests related to waste load allocation in downstream river. The river restoration potential can allocate to the conflicting parties with respect to their claims, by using bankruptcy solution methods. In this research, dischargeable pollution loads to Karun River are determined by pollution sources in various scenarios using... 

Dam construction in arid and semiarid regions is generally related to the risk of increased salinity, due to water passage in contact with salty formations. Hence, it is important to take reservoir thermal and salinity stratification into account in operational rules. In the present study, a simulation–optimization model was developed to determine the amount of water release from various outlets to discharge the brine from hypolimnion layer considering the downstream water quality limitations. The most appropriate time, rate, and concentration to release brine were determined based on water consumption conditions and downstream water demand and river ecology characteristics. The proposed... 

Data related to force-deformation behaviour of soft tissue plays an important role in medical/surgical applications such as realistically modelling mechanical behaviour of soft tissue as well as minimally invasive surgery (MIS) and medical diagnosis. While the mechanical behaviour of soft tissue is very complex due to its different constitutive components, some issues increase its complexity like behavioural changes between the live and dead tissues. Indeed, an adequate quantitative description of mechanical behaviour of soft tissues requires high quality in vivo experimental data to be obtained and analysed. This paper describes a novel laparoscopic grasper with two parallel jaws capable of... 

Various urban, industrial, and agricultural pollutions discharge more than river self-purification potential damages river ecosystem and increases water treatment costs. As different decision-makers and stakeholders are involved in the water quality management in river systems, a new bankruptcy form of the game theory is used to resolve the existing conflict of interests related to waste load allocation in downstream river. The river restoration potential can allocate to the conflicting parties with respect to their claims, by using bankruptcy solution methods. In this research, dischargeable pollution loads to Karun River are determined by pollution sources in various scenarios using... 

In this investigation, a computational-model has been developed, including heat transfer and the effects of the resistance of a metal-mold interface and pressure, for simulation of the solidification process. Simulation of the interface resistance is based on the Zero Thickness Element (ZTE), utilizing the Finite Element Method (FEM). Solid boundary conditions, including contact resistances, have been modified by a pressure gradient in each of the ZTE. The pressure gradient has been modeled, based on experimental data. In order to verify the computational results, an Al-11.5 wt% Si alloy was poured into a permanent mold and the temperature of the interface was measured by a data acquisition... 

A new mathematical model has been developed to simulate mould filling in the lost foam casting process, using the finite difference method. The simulation of molten flow and track of free surfaces is based on the SOLA-VOF numerical technique. An algorithm was developed to calculate the gas pressure of the evaporated foam during the mould filling. The effect of backpressure on the filling behaviour was modelled with an experimental function by adding three-dimensions 3DVOF functions. In order to verify the computational results, a thin grey iron plate was poured into a transparent mould. Cavity filling, foam depolymerization and gap formation were recorded with a 16mm high-speed camera. A...