Sharif Digital Repository

The continuous spread of distributed energy resources (DERs) such as combined heating and power (CHP), diesel generators, boilers and renewable energy sources provide an effective solution to energy related problems to serve the power and heat demands with minimum cost. Moreover, the DERs may play a significant role for supplying power and heat in rural areas, where grid electricity is not available. Also, some dry areas may face water scarcity and salinity problems. So, one important solution is the use of DERs to drive desalination units in order to solve water scarcity and salinity problems. In this study, the optimal scheduling of DERs and reverse osmosis (RO) desalination unit that feed... 

The activity and travel patterns of people with disabilities are generally distinct, as their activities are more dependent on others due to their special physical condition. This paper elaborates on the patterns of regular out-of-home activities (i.e. for different trip purposes) of disabled persons along with the way that they are accompanied to perform the activities. Household Travel Tracker Survey data collected by the Chicago Metropolitan Agency for Planning is used to develop new travel models. Two multinomial logit models are estimated to explore the influential variables and elaborate the consequences of ignoring their inter-dependency. From the influential parameters perspective,... 

Fracture experiments with ball grid array (BGA) specimens having different adherend rigidities were performed under bending loads at intermediate strain rates (0.2–1 s−1) and a high strain rate of 30 s−1. A cohesive zone model (CZM) was established and the predictive capability of the model was assessed for the specimens with different rigidities. The predicted fracture loads were within 12% of the measured forces when the CZM parameters were obtained using specimens with a similar degree of constraint. This suggests that in many practical cases, the effect of adherend stiffness can be neglected in predicting the strength of BGA solder joints. © 2017 Elsevier Ltd  

Musculoskeletal models represent spinal motion segments by spherical joints/beams with linear/nonlinear properties placed at various locations. We investigated the fidelity of these simplified models (i.e., spherical joints with/without rotational springs and beams considering nonlinear/linear properties) in predicting kinematics of the ligamentous spine in comparison with a detailed finite element (FE) model while considering various anterior-posterior joint placements. Using the simplified models with different joint offsets in a subject-specific musculoskeletal model, we computed local spinal forces during forward flexion and compared results with intradiscal pressure measurements. In... 

In this paper, several numerical simulations are performed to study the failure of epoxy adhesive joining composite plates. Different geometries for the joint and its edge are considered, and the effects of these geometries on the failure load are investigated. Moreover, the joints are subjected to different types of loading in order to determine the failure load. The failure theories of composite materials are implemented into the finite element software ABAQUS, and the failure propagation in the joint is studied. © 2020, Shiraz University  

We analyse optimal pricing for a retailer that sells two products using a mixed price bundling strategy. We consider substitutable products, where there is a disutility associated with jointly consuming both products. Mixed price bundling implies that customers can freely choose to buy one of the two products, both of them, or neither of them. The retailer determines the price of each product when it is sold separately, the bundle discount if these two products are sold in a bundle, and the inventory levels for each product. We first derive the optimal price and bundle discount when the store traffic is deterministic. Our results show that the mixed bundling strategy is the most beneficial... 

This paper focuses on the biomechanical aspects of human load carrying in order to provide a physiological framework for designing the more anthropometric assistive systems. An 8degrees-of-freedom musculoskeletal model with twenty functional muscle groups in the lower extremity was developed to simulate the movement in sagittal plane. Inverse dynamics based optimization approach was employed to estimate the excitation level of the muscles. Activation patterns of the muscles illustrate the importance role of the soleus in supporting of the body during load carrying. Also power distribution analysis of the muscles reveals that the plantar flexors of the ankle, extensors of the knee and hip... 

Background: Dynamic knee valgus (DKV) is a common lower extremity movement disorder among females. This study aimed to investigate kinematic couplings between lower extremity joints in female junior athletes with DKV during single and double-leg landing and gait. Methods: Twenty-six physically active female junior athletes (10–14 years old) with DKV were recruited. Kinematic couplings between rearfoot, tibia, knee, and hip were extracted using eight Vicon motion capture cameras and two force plates. Zero-lag cross-correlation coefficient and vector coding were used to calculate kinematic couplings between joints during physical tasks. Paired t-test and Wilcoxon tests were run to find... 

A new 'universal' structural joint with multiple applications was devised. Its application as a 'beam-to-column joint' was already investigated experimentally, and proven to be promising. The results were reported in previous OMAE conferences and elsewhere. Another fruitful application conceived for this joint is in the context of joining (diagonal) braces to the frame members of a structure. In particular, in chevron (inverted V) bracing systems, where the dominating exchanged forces between the combined diagonal braces and the horizontal brace (beam) are 'shear,' the use of the devised joint as a joining member can substantially improve the overall behaviour of the structure under dynamic... 

Patellofemoral joint stability is a result of the restraining effects of the quadriceps muscles, the retinacular structures, and engagement of the bones. The role and significance of these mechanisms in restraining patellar lateral displacement was investigated in this study by measuring the force needed to cause 5 mm lateral displacement (i.e. the mechanical stability, or 'stabilising force') of the patella. Six cadaver knees had 175 N quadriceps load distributed among three muscle groups. With a force ratio matching the muscles physiological cross sectional areas, no significant change occurred in the patellar stabilising force between 0 and 60°knee flexion, but a significant increase... 

Recently, there have been several schemes on concatenated space-time codes. Previous works that do not assume perfect CSI at the receiver suffer from exponential complexity of decoder in rate and 3 db performance loss of differential detection or the complexity of channel estimation [6], [7] due to using trellis structure for differential codes. In this paper, we propose an iterative joint channel estimation and data delection scheme for a concatenated orthogonal space-time block code, which is very simple and reaches coherent performance without assuming perfect CSI available at the receiver. © 2003 IEEE  

This paper designs a Scenario analysis approach to determine the joint production policy for two products under possible substitution. The Scenario analysis is designed to improve decision-making by considering possible outcomes and their implications. The traditional multi-product production models assume that there is no possible substitution between products. However, in real-world cases, there are many substitutable products where substitution may occur in the event of a product stock-out. The proposed model optimizes production quantities for two products under substitution with the aim of minimizing the total cost of the inventory system, including setup and holding costs, subject to a... 

In this paper, we revisit the structure of infeasibility results in network information theory, based on a notion of information state. We also discuss ideas for generalizing a known outer bound for lossless transmission of independent sources over a network to one of lossy transmission of dependent sources over the same network. To concretely demonstrate this, we apply our ideas and prove new results for lossy transmission of dependent sources by generalizing: 1) the cut-set bound; 2) the best known outer bound on the capacity region of a general broadcast channel; and 3) the outer bound part of the result of Maric, Yates, and Kramer on strong interference channels with a common message  

In this paper, we consider lossy source transmission over a Multiple Access WireTap Channel (MAC-WT). In this model, there are two correlated sources, each of them is available at the corresponding encoder. The receiver tries to reconstruct both sources with desired distortions. The sources should be kept secret from an eavesdropper. We propose a joint source-channel scheme for the MAC-WT. In this scheme, each source sequence is mapped to common and private codewords. The common codeword can be decoded by the eavesdropper. The private codeword needs to be kept secret from the eavesdropper by using Wyner's wiretap coding. We also discuss some special cases of the proposed scheme  

Infill materials in rock joints usually cause a reduction in the joint shear strength. The shear behavior of rock discontinuities depends upon whether they are clean and unfilled or filled, so this concern invites accurate understanding of the shear behavior and strength of infilled joints. A series of constant normal load direct shear tests was performed to investigate the shear strength of artificial samples with infilled rough joint surfaces having different asperity and infill characteristics. The current study focuses on the effects of factors that influence the shear strength of infilled rock joints samples, with emphasis on forward and reverse shearing. In the forward cycle, the front... 

In this research, Araldite 2011 has been reinforced using different weight fractions of Reduced Graphene Oxide (RGO). Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) analyses were conducted and it has been shown that introduction of the RGO greatly changes the film morphology of the neat adhesive. Uni-axial tests were carried out to obtain the mechanical characteristics of the adhesive-RGO composites. It has been observed that introducing 0.5 wt% RGO enhances the ultimate tensile strength of the composites by 30%. In addition, single lap joints using neat adhesive and adhesive-RGO composites were fabricated to... 

Games and their use in rehabilitation have formed a new and rapidly growing area of research. A critical hardware component of rehabilitation programs is the input device that measures the patients' movements. After Microsoft released Kinect, extensive research has been initiated on its applications as an input device for rehabilitation. However, since most of the works in this area rely on a qualitative determination of the joints' movements rather than an accurate quantitative one, detailed analysis of patients' movements is hindered. The aim of this article is to determine the accuracy of the Kinect's joint tracking. To fulfill this task, a model of upper body was fabricated. The... 

Connection of truss elements using socket joints is one of the more common practices in the construction of space structures. Although these hollow spherical joints may deform due to the applied loads, these deformations and the resulting effects on the member axial forces are usually ignored in the analysis and design. This work is an investigation of the effects of socket joint deformability on the behavior of space grid structures. Here, the load-deformation relationships obtained from a series of biaxial loading tests on actual socket joints have been used to represent their behavior in several finite-element analysis models. These models have been analyzed using a special-purpose... 

Featuring a nonlinear novel design, Gimbal transmission, is a replacement for traditional robotic joints like gearboxes and revolute joints. This mechanism is one of the most recent types of nonlinear direct transmission (DT) methods in robots. As an alternative for traditional drive methodologies - herein called direct drive transmission (DD) methods, DT provides dynamic coupling and joint interaction attenuation while its capability to be adjusted for a desired task space point, smooth input-output characteristic, and varying reduction ratio lead to a desired force and motion behavior for the whole manipulator. In this paper, design optimization of a gimbal mechanism used as a replacement...