Sharif Digital Repository

The present study investigated the biological treatment of produced water in a microbial electrochemical cell (MXC). The main objectives were to develop a novel spiral microbial electrochemical cell (SMXC) and test its performance for produced water treatment under highly saline conditions (salinity > 200000 ppm). The bioelectrochemical performance of the system was also evaluated in terms of power and hydrogen production over time. The comparatively inexpensive material and ease of application increased the feasibility of the SMXC configuration for produced water treatment. Optimal SMXC performance as a microbial fuel cell was achieved at a maximum open circuit potential of 330 mV, maximum... 

A successful design, previously adapted for treatment of complex wastewaters in a microbial fuel cell (MFC), was used to fabricate two MFCs, with a few changes for cost reduction and ease of construction. Performance and electrochemical characteristics of MFCs were evaluated in different environmental conditions (in complete darkness and presence of light), and different flow patterns of batch and continuous in four hydraulic retention times from 8 to 30h. Changes in chemical oxygen demand, and nitrate and phosphate concentrations were evaluated. In contrast to the microbial fuel cell operated in darkness (D-MFC) with a stable open circuit voltage of 700mV, presence of light led to growth of... 

With increasing use of computers in everyday life, improved communication between machines and human is needed. To make a right communication and understand a humankind face which is made in a graphical environment, implementing the audio and visual projects like lip reading, audio and visual speech recognition and lip making are needed. Lack of a complete audio and visual database for this application in Farsi language made us provide a new complete Farsi database for this project that is called SFAVD. It is a unique audio and visual database which in addition to considering Farsi conceptual and speech structure, it considers influence of speech on lip changes. This database is created for... 

With the growing presence of computers in everyday life, communication improvement between human and machines is inevitable. Talking faces are the faces whose movements are synchronized to speech. They have an effective role in many applications. Lip is the most important part of a talking face. The main goal of this project is implementing a natural and human-like lip movement synthesis system for the Farsi language. For this purpose, a comprehensive audio visual database called SFAVD1 was designed and used. After extracting the sufficient features and designing a parallel Hidden Markov Model, the speech driven lip movement sequence generator system for Farsi input speech was implemented.... 

In this Paper a new approach is proposed for electrocardiogram (ECG) based human identification using wavelet distance measurement. The main advantage of this method is that it guarantees high accuracy even in abnormal cases. Furthermore, it possesses low sensitivity to noise. The algorithm was applied on 11 normal subjects and 10 abnormal subjects of MIT-BIH Database using single lead data, and a 100% human identification rate was on both normal and abnormal subjects. Adding artificial white noise to signals shows that the method is nearly accurate in SNR level above 5dB in normal subjects and 20dB in abnormal subjects  

Limit cycle walkers are known as a class of walking robots capable of presenting periodic repetitive gaits without having local controllability at all times during motion. A well-known subclass of these robots is McGeer’s passive dynamic walkers solely activated by the gravity field. The mathematics governing this style of walking is hybrid and described by a set of nonlinear differential equations along with impulses. In this paper, by applying perturbation method to a simple model of these machines, we analytically prove that for this type of nonlinear impulsive system, there exist different switching surfaces, leading to the same equilibrium points (periodic solutions) with different... 

Electrocardiogram is one of the most prominent cardiac signals being capable to be utilized for medical uses such as arrhythmia detection. Over the years, the feasibility of using this signal for human identification issue has been investigated, and some methods have been proposed. In this Paper a novel approach is proposed for electrocardiogram (ECG) based human identification using Extended Kalman Filter (EKF). The innovation signal of EKF has been considered as feature which is used to classify different subjects. In this paper a general issue, human identification, is summarized to a classification problem in which the proposed features of each subject is calculated, and the... 

Inspired by the effects of a switching surface on the stability of passive dynamic walking (Safa and Naraghi in Robotica 33(01):195–207, 2015; Safa et al. in Nonlinear Dyn. 81(4):2127–2140, 2015), this paper suggests a new control strategy for stabilization of dynamic bipedal locomotion. It verifies that the stability improvement of a dynamic walking system is feasible while preserving the speed, step-length, period, natural dynamics, and the energy effectiveness of the gait. The proposed control policy goes behind the three primary principles: (i) The system’s switching surface has to be replaced by a new one if an external disturbance is induced. (ii) The new switching surface has to be... 

Inspired by the effects of a switching surface on the stability of passive dynamic walking (Safa and Naraghi in Robotica 33(01):195–207, 2015; Safa et al. in Nonlinear Dyn. 81(4):2127–2140, 2015), this paper suggests a new control strategy for stabilization of dynamic bipedal locomotion. It verifies that the stability improvement of a dynamic walking system is feasible while preserving the speed, step-length, period, natural dynamics, and the energy effectiveness of the gait. The proposed control policy goes behind the three primary principles: (i) The system’s switching surface has to be replaced by a new one if an external disturbance is induced. (ii) The new switching surface has to be... 

The main focus of this paper is on how the biped robot has a stable passive gait cycle as well as going through a stable journey on a level ground merely with push-off actuation. During recent years humanoids have been in the center of attention due to several reasons some of which are: compactness of the structure, low energy consumption, humanoid behavior and last but not least being of great use in medical field. In this paper, equations of motion regarding the passive phase as well as push-off are simulated in MATLAB software. For the next step, a comparison between these two stable gait cycles is made so as to figure out the difference between energy injected to the system by push-off... 

Purpose - A numerical method is developed to capture the interaction of solid object with two-phase flow with high density ratios. The current computational tool would be the first step of accurate modeling of wave energy converters in which the immense energy of the ocean can be extracted at low cost. Design/methodology/approach - The full two-dimensional Navier-Stokes equations are discretized on a regular structured grid, and the two-step projection method along with multi-processing (OpenMP) is used to efficiently solve the flow equations. The level set and the immersed boundary methods are used to capture the free surface of a fluid and a solid object, respectively. The full...