Sharif Digital Repository

The g-C3N4/Fe2O3 nanocomposite was produced by the combustion synthesis. The product was characterized by x-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller study (BET), Ultraviolet-visible analysis (UV-vis) and photoluminescence measurement (PL). Effect of iron nitrate on stability and photocurrent density under simulated visible-light irradiation was determined. The highest photocurrent density obtained (4.25 μA/Cm2) was twelve times the pure g-C3N4. This improvement was due to a bandgap decrease, the specific surface area increase, reduction of the electron-hole recombination, and... 

Studying data flows in conventional applications of Multi-Processor System-on-Chips (MPSoCs) denotes that most of these flows are the ones that transfer huge volume of data in inter-core communications. Previous works try to present architecture for interconnection network which some paths with low power and latency are reserved (statically or dynamically). However all of the presented methods are based on subnetworks or mechanism of transferring control messages (to establish a path and tear it down after transmission of data). Optical connections with low cost, low power and high bandwidth are good candidates to reduce power consumption of Network-on-Chips (NoCs). Therefore, using optical... 

Increasing of human demanding for energy and limiting of fossil fuels and bio-logical problems, it seems necessary to access new and clean source of ener-gy. For instance, one of these sources of energy is sun. If we can impart from this infinite energy source so health and natural life can be pictured for human. Nanostructure dye sensitized solar cells in compare with other photovoltaic cells are more economical and practical as a result of lower material cost and simpler manufacturing process. In general, a typical dye sensitized solar cell is a sandwich structure based on two transparent conducting oxide (FTO) glasses. The FTO glass substrates are expensive and account for most of... 

Existing processes to improve the quality of heavy oil cuts catalytic converter hydroconversion can be mentioned in the slurry phase. This process is usually done in the temperature 440˚C to 470˚C be a heavy craking led to the production of light weight thermal feed can be more. With more products light, adverse reaction can also lead to the formation of coke be. Coke formation of secondary radical reactions can be feed from cracking of heavy compounds. Coke production is to eliminate or limit the ability of homogeneous catalysts (eg sulfide Molybdium) about 600-1000 ppm disposable food adds to be used. The main role of catalyst in the stable radicals fail thermal compound feed is heavy. The... 

Posterior lumbar surgery is often associated with extensive injuries to back muscles. In this thesis, the effect of such iatrogenic injuries in some patients was examined. For this purpose, the CSA of back muscles in 6 patients were measured using MR scan. To examine any natural change in CSAs of healthy people or instrument errors, same measurement were carried out on 10 healthy volunteers. In addition, a detailed anatomical model of an intact human spine was developed. With the aim of experimental studies and intact model, the post-operative model of patients was also developed. These two models were used to quantizing the change in activity of back muscles during some symmetric, normal... 

Low back pains (LBP) are prevalent and costly. One of the important factors causing LBP is excessive axial compression and shear forces that are applied on the intervertebral discs during different activities. Due to lack of direct in vivo measurement methods for estimating these loads, musculoskeletal biomechanical models have been emerged as indispensable tools under various activities. Different biomechanical models have been suggested to estimate muscle forces and spinal loads base on optimization, EMG and hybrid (EMG assisted optimization, EMGAO) methods. Although there have been a number of studies on the differences between various optimization and EMG-based methods, there has been no... 

The 1991 NIOSH Lifting Equation (NLE) is widely used to assess risk of injury to the spine by providing estimates of the recommended weight limit (RWL) in hands. The present study uses two biomechanical models of the spine to verify whether the RWL generates L5-S1 loads within the limits (e.g., 3400 N for compression recommended by NIOSH and 1000 N for shear recommended in some studies).Severallifting activities are simulated here to evaluate the RWL by the NLE and the L5-S1 loads by the models. In lifting activities involving moderate to large forward trunk flexion, the estimated RWL generates L5-S1 spine loads exceeding the recommended limits. The NIOSH vertical multiplier is the likely... 

Direct in vivo measurements of spinal loads and muscle forces are invasive. Investigators have thus used musculoskeletal biomechanical models that require kinematic data including trunk and pelvis angular movements as their inputs. . Novel devices measure anglular movements using both inertial sensors (such as gyroscopes and accelerometers) and miniature magnetometers. Relative low cost, portability, and accuracy are among specific characteristics of inertial tracking devices. The main objective of the present study was set to measure spinal kinematics including the lumbopelvic rhythm as the ratio of total lumbar rotation over pelvic rotation during trunk sagittal movement which is essential... 

Range of motion (ROM) of the thoracic spine has implications in patient discrimination for diagnostic purposes and in biomechanical models for predictions of spinal loads. Few previous studies have reported quite different thoracic ROMs. Total (T1-T12), lower (T5-T12) and upper (T1-T5) thoracic, lumbar (T12-S1), pelvis, and entire trunk (T1) ROMs were measured using an inertial tracking device as asymptomatic subjects flexed forward from their neutral upright position to full forward flexion. Correlations between body height and the ROMs were conducted. Effect of measurement errors of the trunk flexion (T1) on the model-predicted spinal loads was investigated. Mean of peak voluntary total... 

Etiological studies proves the fact that Low Back Pain (LBP) is one of the most expensive and prevalent desease all over the world. This fact illustrates the reqiurment of the special effort in ordet to reducing the pain due to this problem. Finite element modeling of human spine is one the suitable methods to simulate the behavior of human spine in different loading conditions. These conditions could be different daily occupational tasks. There is two general viewpoint toward finite element modeling of human spine. The fisrt method focuses on the detailed geometry and mechanical properties of spine, while the other complexities such as detailed muscle forces are overlooked. The latter... 

Musculoskeletal abnormalities affect joints and change their range of motion (RoM). Correcting these abnormalities thoroughly depends on the information related to the normal spine movement. Therefore, spine motion analysis can be used as an important tool to distinguish between healthy and patient individuals as well as to determine the intensity of such diseases. Additionally, existing biomechanical models need kinematics data in order to analyze spinal forces. The present study hence aims to measure 3D range of motion of thoracic and lumbar spine using inertial sensors. Their small size, portability, low weight, and relatively low cost make inertial sensors as indispensable tools in... 

The spine like every other mechanical pillar, is exposed to buckling and loss of stability. While existing biomechanical models emphasize the pressure force on the disk as the main cause of injury, there is also a possibility of local buckling phenomenon in vertebral discs. Because of the prevalence and high cost of lower back pain, it is essential to evaluate the forces carried by disks and lumbar muscles during occupational activities more accurately. In this regard, hybrid EMG-assisted optimization (EMGAO) approaches are most common methods for estimation of spinal loads. These models, not only use EMG data to be physiologically creditable, but also satisfy equilibrium requirements at all... 

There is a large, at times contradictory body of investigations relating low back pain and spinal curvature in sagittal plane. The previous studies have not been subject-specified, and they have not considered the active tissues in the models. The mechanical load has a significant impact on the prevalence of low back pain and the geometry of lumbar spine in the sagittal plane is one of the most important characteristics in determining the load sharing of the spine. Thus, it is essential to know how the geometry load affects the load sharing of the lumbar spine. As a matter of fact, the purpose of this project is to know how the geometry of the lumbar spine affects the load sharing. Thus,... 

Low back pain is one of the most prevalent musculoskeletal injuries in occupational activities. In order to reduce or prevent it, it is necessary to estimate the mechanical loads of body joints. Direct measurement of spinal loads is invasive and costly. Therefore, musculoskeletal modeling is a convenient tool in estimation of joints and muscles loads that often uses kinematics information as input.Marker-based motion capture systems are one of the most common ways for the estimation of body kinematics. Unfortunately, they are time consuming and expensive. Thus being marker-free and low-cost, Microsoft Kinect is a suitable alternative. Recent studies often have investigated accuracy of... 

According to epidemiological studies, low back pain is the most prevalent musculoskeletal disease thus indicating the important role of biomechanical engineers to manage risk of injury. Different quantitative (i.e., biomechanical models) and qualitative (empirical) assessment tools are used to evaluate risk of musculoskeletal injuries. The present study uses various quantitative and qualitative risk assessment tools to investigate the risk of injury among workers in Iran Khodro Automaker company (IKCO) assembly hall No. 3 (Pars Peugeot car assembly). Moreover, different engineering and administrative interventions are suggested to manage risk of musculoskeletal injuries when needed. The... 

Objective: To assess adequacy of the National Institute for Occupational Safety and Health (NIOSH) Lifting Equation (NLE) in controlling lumbar spine loads below their recommended action limits during load-handling activities in the stoop and squat using a detailed musculoskeletal model,that is, the AnyBody Modeling System.Background: The NIOSH committee employed simplistic biomechanical models for the calculation of the spine compressive loads with no estimates of the shear loads. In addition, NLE does not include the posture of the knee during manual material handling. It is therefore unknown whether the NLE would adequately control lumbar compression and shear loads below their...