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- Genre: Masters Thesis
- Creators: Arizona State University
- Creators: Chakraborty, Bijeta
- Creators: Peterson, Cory
- Member of: ASU Electronic Theses and Dissertations
Description
The construction industry in India suffers from major time and cost overruns. Data from government and industry reports suggest that projects suffer from 20 to 25 percent time and cost overruns. Waste of resources has been identified as a major source of inefficiency. Despite a substantial increase in the past few years, demand for professionals and contractors still exceeds supply by a large margin. The traditional methods adopted in the Indian construction industry may not suffice the needs of this dynamic environment, as they have produced large inefficiencies. Innovative ways of procurement and project management can satisfy the needs aspired to as well as bring added value. The problems faced by the Indian construction industry are very similar to those faced by other developing countries. The objective of this paper is to discuss and analyze the economic concerns, inefficiencies and investigate a model that both explains the Indian construction industry structure and provides a framework to improve efficiencies. The Best Value (BV) model is examined as an approach to be adopted in lieu of the traditional approach. This could result in efficient construction projects by minimizing cost overruns and delays, which until now have been a rarity.
ContributorsNihas, Syed (Author) / Kashiwagi, Dean (Thesis advisor) / Sullivan, Kenneth (Committee member) / Kashiwagi, Jacob (Committee member) / Arizona State University (Publisher)
Created2013
Description
Efficiency of components is an ever increasing area of importance to portable applications, where a finite battery means finite operating time. Higher efficiency devices need to be designed that don't compromise on the performance that the consumer has come to expect. Class D amplifiers deliver on the goal of increased efficiency, but at the cost of distortion. Class AB amplifiers have low efficiency, but high linearity. By modulating the supply voltage of a Class AB amplifier to make a Class H amplifier, the efficiency can increase while still maintaining the Class AB level of linearity. A 92dB Power Supply Rejection Ratio (PSRR) Class AB amplifier and a Class H amplifier were designed in a 0.24um process for portable audio applications. Using a multiphase buck converter increased the efficiency of the Class H amplifier while still maintaining a fast response time to respond to audio frequencies. The Class H amplifier had an efficiency above the Class AB amplifier by 5-7% from 5-30mW of output power without affecting the total harmonic distortion (THD) at the design specifications. The Class H amplifier design met all design specifications and showed performance comparable to the designed Class AB amplifier across 1kHz-20kHz and 0.01mW-30mW. The Class H design was able to output 30mW into 16Ohms without any increase in THD. This design shows that Class H amplifiers merit more research into their potential for increasing efficiency of audio amplifiers and that even simple designs can give significant increases in efficiency without compromising linearity.
ContributorsPeterson, Cory (Author) / Bakkaloglu, Bertan (Thesis advisor) / Barnaby, Hugh (Committee member) / Kiaei, Sayfe (Committee member) / Arizona State University (Publisher)
Created2013
Description
Class D Amplifiers are widely used in portable systems such as mobile phones to achieve high efficiency. The demands of portable electronics for low power consumption to extend battery life and reduce heat dissipation mandate efficient, high-performance audio amplifiers. The high efficiency of Class D amplifiers (CDAs) makes them particularly attractive for portable applications. The Digital class D amplifier is an interesting solution to increase the efficiency of embedded systems. However, this solution is not good enough in terms of PWM stage linearity and power supply rejection. An efficient control is needed to correct the error sources in order to get a high fidelity sound quality in the whole audio range of frequencies. A fundamental analysis on various error sources due to non idealities in the power stage have been discussed here with key focus on Power supply perturbations driving the Power stage of a Class D Audio Amplifier. Two types of closed loop Digital Class D architecture for PSRR improvement have been proposed and modeled. Double sided uniform sampling modulation has been used. One of the architecture uses feedback around the power stage and the second architecture uses feedback into digital domain. Simulation & experimental results confirm that the closed loop PSRR & PS-IMD improve by around 30-40 dB and 25 dB respectively.
ContributorsChakraborty, Bijeta (Author) / Bakkaloglu, Bertan (Thesis advisor) / Garrity, Douglas (Committee member) / Ozev, Sule (Committee member) / Arizona State University (Publisher)
Created2012
Description
Saudi Arabia has been having many issues with large construction projects such as delays, low performance and high cost. Some studies show that around 70% of the public projects in Saudi Arabia are delayed. These issues have resulted from many factors. One of the factors believed to be delaying projects is the Saudi procurement system. The Saudi procurement system only selects contracts based on the lowest bid price offered. However, the Saudi procurement system has been found to not only produce delayed low quality projects, but also has resulted in higher costs.
This paper shows how to modify the Saudi procurement system by implementing a clarification phase, which is the most important phase in the Performance Information Procurement System (PIPS). The clarification phase requires the bid’s winning contractor to submit a project scope, a project schedule, to identify risks that not their responsibility, performance measurements and a milestone schedule. The PIPS system has been one of the most successful systems around the world and has shown a 98% success rate in six different countries with risks and cost reductions up to 30%.
This research conducted a survey of 157 engineers, 33 consultants, 9 owners, 5 vendors, 13 academics, and 28 architects to develop the public procurement system in Saudi Arabia. The participants work in government sectors with an interest in the Saudi Arabian procurement system. 80.61 % of participants believe that the traditional Saudi procurement system consistently selects poor performing contractors. Moreover, 95.97% of participants think that the selection of contractors based only on the lowest price criterion affects projects negatively. Also, 96.20% of participants in the survey feel that there needs to be a change in the traditional Saudi Arabian procurement system. 88.7% of participants agree to require the contractor to identify risks, and 96.03 % of participants agree that the contractors must have a plan. Moreover, 95.45% of participants agree to require a contractor review the scope of a project and verify that it is correct. Finally, 82.18% of participants agree to require a contractor to resolve all owner concerns before signing a contract to improve construction projects performance. The paper shows the need to change the Saudi procurement system and a solution to this growing problem.
This paper shows how to modify the Saudi procurement system by implementing a clarification phase, which is the most important phase in the Performance Information Procurement System (PIPS). The clarification phase requires the bid’s winning contractor to submit a project scope, a project schedule, to identify risks that not their responsibility, performance measurements and a milestone schedule. The PIPS system has been one of the most successful systems around the world and has shown a 98% success rate in six different countries with risks and cost reductions up to 30%.
This research conducted a survey of 157 engineers, 33 consultants, 9 owners, 5 vendors, 13 academics, and 28 architects to develop the public procurement system in Saudi Arabia. The participants work in government sectors with an interest in the Saudi Arabian procurement system. 80.61 % of participants believe that the traditional Saudi procurement system consistently selects poor performing contractors. Moreover, 95.97% of participants think that the selection of contractors based only on the lowest price criterion affects projects negatively. Also, 96.20% of participants in the survey feel that there needs to be a change in the traditional Saudi Arabian procurement system. 88.7% of participants agree to require the contractor to identify risks, and 96.03 % of participants agree that the contractors must have a plan. Moreover, 95.45% of participants agree to require a contractor review the scope of a project and verify that it is correct. Finally, 82.18% of participants agree to require a contractor to resolve all owner concerns before signing a contract to improve construction projects performance. The paper shows the need to change the Saudi procurement system and a solution to this growing problem.
ContributorsAlofi, Ahmed Abdulrahman (Author) / Kashiwagi, Dean (Thesis advisor) / Sullivan, Kenneth (Committee member) / Kashiwagi, Jacob (Committee member) / Arizona State University (Publisher)
Created2015
Description
In this thesis, a digital input class D audio amplifier system which has the ability
to reject the power supply noise and nonlinearly of the output stage is presented. The main digital class D feed-forward path is using the fully-digital sigma-delta PWM open loop topology. Feedback loop is used to suppress the power supply noise and harmonic distortions. The design is using global foundry 0.18um technology.
Based on simulation, the power supply rejection at 200Hz is about -49dB with
81dB dynamic range and -70dB THD+N. The full scale output power can reach as high as 27mW and still keep minimum -68dB THD+N. The system efficiency at full scale is about 82%.
to reject the power supply noise and nonlinearly of the output stage is presented. The main digital class D feed-forward path is using the fully-digital sigma-delta PWM open loop topology. Feedback loop is used to suppress the power supply noise and harmonic distortions. The design is using global foundry 0.18um technology.
Based on simulation, the power supply rejection at 200Hz is about -49dB with
81dB dynamic range and -70dB THD+N. The full scale output power can reach as high as 27mW and still keep minimum -68dB THD+N. The system efficiency at full scale is about 82%.
ContributorsBai, Jing (Author) / Bakkaloglu, Bertan (Thesis advisor) / Arizona State University (Publisher)
Created2015
Description
This thesis presents a literature research analyzing the cost overrun of the construction industry worldwide, exploring documented causes for cost overrun, and documented parties responsible for the inefficiency. The analysis looks at a comparison between the metrics of construction projects in different continents and regions. Multiple publication databases were used to look into over 300 papers. It is shown that although construction demands are increasing, cost overrun on these projects is not decreasing at the same rate around the world. This thesis also presents a possible solution to improve cost overrun in the construction industry, through the use of the Best Value Performance Information Procurement System (BV PIPS). This is a system that has been utilized in various countries around the world, and has documented evidence that it may be able to alleviate the overrun occurring in the construction industry.
ContributorsGoyal, Abhinav (Author) / Kashiwagi, Jacob (Thesis advisor) / Kashiwagi, Dean (Committee member) / Chong, Oswald (Committee member) / Arizona State University (Publisher)
Created2017