Sharif Digital Repository

Mass transfer and axial dispersion coefficients for continues phase were calculated by axial mixing model for continues phase and forward mixing model for dispersed phase simultaneously. Experimental data was achieved in pulsed sieve plate column with 22 cm diameter. Toluene –water-acetone and Butanol-Succinic acid- water were used in this experiment. In these systems continues phase is water and mass transfer takes place from continues phase to dispersed phase. Experimental data involves drop size distributions and operating conditions andconcentration in both phases.For calculating overall mass transfer coefficient for drops the handlos and Baron Model was used. The axial dispersion... 

By combustion, waste toxic, flammable and corrosive materials are changed to less inviromental problems by combustion. It also creats environmental problems (the most serios problem is caused by burning gases), as well as economic resources are wasted. So several ways was investigated to reduce combustion gases. Mini-methanol plant is one of varios possible ways that can convert these gases in to methanol. So methanol plant was simulated and then pinch analysis was performed on the simulated plant. Performing of pinch analysis caused 94.5 percent and 25 percent reduction in amaunt of hot and cold utility respectively. Before and after pinch analysis, the exergy analysis was performed on... 

In this thesis a novel T type scheme for direct ac/ac converters is proposed. In this topology, frequency changing takes place directly (without common DC voltage bus) through three converters that are connected in a T structure. H-bridge converters are implemented in each branches of T to make the proposed converter. Also, multilevel inverters, specially cascaded H-bridge ones can be used in branches of T. this will lead to a multilevel ac/ac converter that is suitable for high power applications such as intertie connections and high power motor drives. Using half-bridge converters as T branch converters, leads to an ac/ac converter with unity power factor by only six semiconductor... 

One of the main challenges in the design of wireless sensor networks (WSNs) is minimizing the energy consumption while simultaneously maximizing the performance of sensors. In this thesis, we have considered WSNs based on beacon enabled IEEE 802.15.4/Zigbee Standards with low rate applications like temperature, humidity and light sensing, which mainly have been used in a smart home environment, and proposed a cross-layer design to overcome this challenge. The design involves an optimizer module that captures the application layer and MAC sub layer behaviors. Based on these behaviors, the optimizer dynamically changes the rate of node’s traffic at the application layer and the priority of... 

We present a home energy management system that is able to manage home energy demand and resources to achieve minimum household payment in electricity dynamic pricing.Communication is used to collect needed data from the home energy system members and users in order toimprove demand and resources management. Some of the needed data comes from appliances and solar panels by wireless sensor network and some other is received from home users by a user interface.
Two algorithms are proposed that the first algorithm goal is to minimizing household payment and the second algorithm goals are flexible implementiation and decreasing household payment. To decrease household payment, these... 

Home health care is one of the newest methods of providing services to patients in developed societies that can respond to the individual lifestyle of the modern age and increase of life expectancy. In this study, a new mathematical model is developed taking into account the flexibility of starting and ending locations of each nurse, according to the specific requirements of each service. In this context, there are some special services that require the picking of materials and health equipment from laboratory or force the nurse to return to laboratory to deliver the specimens and equipment. In the next step, this model is expanded to downgrading aspects by adding the objective of minimizing... 

Today, smart devices have become an integral part of everyday life. The Android operating system is also the most popular operating system of these devices, and as a result, various malwares are produced and distributed for this operating system every day. This makes it especially important to investigate these malwares. This includes finding people involved in the development and distribution of malware, as well as discovering other malwares created by them. Discovering other involved entities, such as social media accounts, websites, Android store accounts, and taking steps to prevent malware from being distributed by them is another aspect of this story. In order to deal with organized... 

Automatic recognition of musical Maqams has been one of the challenging problems in Music Information Retrieval. Despite the increasing amount of related research in recent years, we are still far away from building related real-life applications. Nevertheless, a very small portion of these research is dedicated to automatic recognition of Maqams in recitation of the Holy Quran. In this thesis, as a first attempt, we have used machine learning methods to classify six Maqam families which are commonly used in Quran recitation. Also, due to the lack of pre-exisiting datasets, we have annotated approximately 1325 minutes of Tadwir recitation from two prominent Egyptian reciters, i.e., Muhammad... 

This thesis examines the modal characteristics of the payload after connecting to the carrier via the adapter. Basically, the modal characteristics of a payload change after connection to the carrier due to the different stiffness of the coupling mechanism. In this report, it is attempted to split and model the assembly structural system into two substructures interconnected by the V band clamp mechanism. Then, each of the substructures analyze individually and the modal characteristics of the integrated system are extracted using the infrastructure coupling methods. The coupling method is the "Component Mode synthesis" (CMS) method and input data, dynamic and modal characteristics required... 

The structure performances during past earthquakes indicate the importance of predicting behaviors of irregular structures under earthquakes. If the irregularity exceeds an expected limit, a seismic analysis should be carried out by a dynamic analysis method. The Endurance Time (ET) is a time-history method, base on dynamic analysis for seismic analyzing and designing the structures, in which structures are subjected to intensifying accelerogram functions and their Endurance Time is measured. One of the most applicable methods for RCF analysis is the Concentrated Hinge Model which is used in this research too. The needed parameters for modeling plasticity in concentrated hinge are achieved...