Sharif Digital Repository

In this paper, a fully integrated 900-MHz CMOS differential power amplifier (PA) with new power combiner is designed and fabricated in a 0.18- um technology. For the high power CMOS PA design, new transformer network and the number of power stages is fully analyzed and optimized to find inductors dimensions. A parallel combination of the Class AB and the Class C amplifier or multiple gated common source transistors in power stages was used to improve both the linear operating range and the power efficiency simultaneously. The PA delivers an output power of 29 dBm and a power-added efficiency of 24% with a power gain of 20 dB, including the losses of the bond-wires. Copyright © 2009 Praise... 

Several methods have been proposed in data envelopment analysis (DEA) for measuring efficiency in problems with interval or ordinal data. In this study, we review the weaknesses and drawbacks of these methods and show how converting ordinal or interval data into precise data can lead to violations of established DEA axioms. One of the axioms violated by these conversion processes is the inclusion of observations axiom, which requires a consistent definition of the production possibility set. We describe the special properties of ordinal and interval data together with their effect on the DEA-based rankings using a theorem and an example. We also propose a new algorithm and apply random... 

Several methods have been proposed in data envelopment analysis (DEA) for measuring efficiency in problems with interval or ordinal data. In this study, we review the weaknesses and drawbacks of these methods and show how converting ordinal or interval data into precise data can lead to violations of established DEA axioms. One of the axioms violated by these conversion processes is the inclusion of observations axiom, which requires a consistent definition of the production possibility set. We describe the special properties of ordinal and interval data together with their effect on the DEA-based rankings using a theorem and an example. We also propose a new algorithm and apply random... 

One of the pillars of any machine learning model is its concepts. Using software engineering, we can engineer these concepts and then develop and expand them. In this article, we present a SELM framework for Software Engineering of machine Learning Models. We then evaluate this framework through a case study. Using the SELM framework, we can improve a machine learning process efficiency and provide more accuracy in learning with less processing hardware resources and a smaller training dataset. This issue highlights the importance of an interdisciplinary approach to machine learning. Therefore, in this article, we have provided interdisciplinary teams' proposals for machine learning. © 2021... 

In this work, an exergy analysis is performed for the waste heat recovery section (WHRS) of the steam-natural gas reforming (SNGR) process as a major energy intensive process. Two alternate conditions are investigated to evaluate the required thermodynamic parameters: normal operating condition and increase of C2+ components in the process feed stream. At normal operating condition, the exergy efficiency of WHRS amounts to 0.58 while some 17.2 kJ energy is destructed for each mole of H2 produced. If heavier than methane components are increased in the feed up to 8.5 mole %, despite the increase of H2 production, the exergy efficiency decreases down to 0.54... 

Green iron oxide pellets are indurated with thermal treatment in pelletizing plant to achieve sufficient mechanical properties and to be used in iron-steel industry. In the first stage, the pellets are dried with hot air coming from the firing unit. High heat transfer makes the evaporation rate exceeding the outgoing steam rate from the pellets and as a result, increasing the inner pressure of the pellets and fragment. On the other hand, low heat transfer causes low production rate. Using the related equations and considering the pellets' moisture and porosity and applying the pellets' condition on parameters such as specific heat capacity and heat conductivity, an acceptable standard is... 

Since the failure of resources fatally affects processor allocation, a fault tolerant service is essential in the interconnection networks. In this paper, a new fault tolerant method is proposed and evaluated in the hybrid processor allocation scheme, which we have introduced in our previous work. Our task consists of two independent phases. First, the allocation process executes to allocate an efficient set of processors to the requested submesh. The second phase comes to work when the faulty nodes are detected in the allocated spaces. The selected processor allocation scheme allows jobs to be executed without waiting, provided that the number of processors is sufficient in the system and... 

A pyrophosphate based solution, as an acidic electrolyte, was developed for bronze electroplating. By using a statistical experimental design, response surface method, the effects of five factors [copper concentration (Cu), tin concentration (Sn), pyrophosphate concentration (P), current density j and pH] on the composition of the electroplated alloy as well as the process efficiency were evaluated. Statistical analysis indicated that all the parameters were significant and a second order polynomial model was successfully fitted to the data for both the alloy composition and the process efficiency. Based on the results obtained, a solution of Cu(II)8.04 g L -1, Sn(II)=26.36 g L -1, P=113.22... 

The condensation process is of great importance in many heat transfer devices in which a large amount of energy must be transferred. Furthermore, condensation is a crucial part of energy conversion and affects the energy efficiency of thermal desalination plants and solar stills. During the condensation process in solar stills, an essential part of the energy is transferred through the condensation surface to produce fresh water. Therefore, the condensation surface plays a significant role in the working efficiency of solar stills. The wettability of the condensation surface influences the condensation mechanism, which, in turn, affects the efficiency of solar stills. This study aims to...