Tuesday, October 18, 2011

Experiments in Robot Formation Control with an Emphasis on Decentralized Control Algorithms (Mechanical Project)


In this project, several algorithms and experiments involving the control of robot formations are presented. The algorithms used were focused on decentralized control. The experiments were implemented on two different experimental testbeds consisting of teams of wheeled mobile robots. The robots used are described along with their sensors and supporting hardware. Also, there is a discussion of the programming framework used to build the control software.
The first control algorithm and experiment uses a robust consensus tracking algorithm to control a formation of robots to track a desired trajectory. The robots must maintain the correct formation shape while the formation follows the trajectory. This task is complicated by limited communication between the robots, and disturbances applied to the information exchange. Additionally, only a subset of the robots have access to the reference trajectory.
In the second experiment, the same algorithm was re-implemented in a decentralized way, which more effectively demonstrated the goals of the algorithm. The second algorithm involves controlling a formation of robots without a global reference frame. In order to accomplish this, the formation description is reformulated into variables describing the relative positions of the robots, and vision-based measurements are used for control.
A homography-based technique is used to determine the relative positions of the robots using a single camera. Then a consensus tracking controller similar to the one used previously is used to distribute the measured information to all of the robots. This is done despite the fact that different parts of the information are measured by different agents.

Project Report on Corporate Finance (Management Project)


Over the past twenty years, write-offs have grown in popularity. With the increased usage of write-offs, it is becoming more important to understand the mechanisms behind why companies take write-offs and how write-offs affect company performance.
In this paper, I examine the cross-sectional determinants of the decision to take write-offs. I use a hand-collected dataset on write-offs that is much more comprehensive than existing write-off datasets. Contrary to much hype and scandals surrounding a few write-offs, I find that quality of governance is positively related to write-off decisions in the cross-section. My results also suggest that poor governance companies wait to take write-offs until it becomes inevitable, while well-monitored companies take write-offs sooner. As a result, the charge is substantially larger than the average write-off charge.
When these poor governance companies announce write-offs, the announcement generates negative abnormal returns. However, when good corporate governance companies announce write-offs, the charge is substantially smaller than the average charge. These well-monitored companies take write-offs immediately following a problem. Following the write-off announcements of these types of companies, average announcement day effects exceed a positive six percent. These results suggest that companies with quality monitoring mechanisms use write-offs in a manner that is consistent with enhancing shareholder value.
In my second essay I examine the effect of write-off announcements on the stock market liquidity of firms taking write-offs from 1980 to 2000. I find that there are substantial improvements in stock market liquidity following corporate write-offs. Spreads decrease and turnover volume increases after write-off announcements, which indicates an improvement in liquidity. The liquidity improvement is greater for better governed companies. I decompose bid-ask spreads and show that adverse selection costs decrease substantially as market participants respond to the write-off announcement. The evidence suggests a liquidity benefit of write-offs that must be weighed against any other perceived cost of write-offs. Such a liquidity benefit may validate that write-offs convey favorable information about the firm.
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Tuesday, October 11, 2011

The Role of DAP-Kinase in Modulating Vascular Endothelial Cell Function Under Fluid Shear Stress (Biomedical Project)


Atherosclerosis preferentially develops in vascular regions of low or disturbed flow and high spatial gradients. Endothelial cells that line the vessel walls actively participate in translating mechanical stimuli, shear stress due to fluid flow, into intracellular signals to regulate cellular activities. Atherosclerosis is a chronic disease. During its development, a cascade of inflammatory signals alters the arterial endothelial homeostatic functions.
Death-associated protein (DAP) kinase and its correlated pathway have been associated with cell apoptosis, turnover, and cytoskeleton remodeling in cellular networks, ultimately leading to changes in cell motility and vascular wall permeability. DAP-kinase is also highly regulated by inflammatory triggers such as TNF-α. This thesis investigates DAP-kinase modulation due to shear stress, and the role of DAP-kinase activity in endothelial responses toward applied shear stress. Using bovine aortic endothelial cells (BAEC), DAP-kinase expression is demonstrated in both sheared (10 dynes/cm2) and static conditions. Overall DAPK expression increased with extended shearing, while the presence of phosphorylated DAPK decreased with applied shear stress, as demonstrated in Western blot analysis.
In correlation, DAPK RNA expression profiles were explored to understand pre-translational behavior and to understand just how shear stress influences DAPK expression over time. There is a temporal increase in DAPK mRNA, occurring at earlier time points when compared to DAPK protein expression, displaying the precedence of mRNA expression leading to increased translation into protein.
From our apoptosis assay results, shear stress reduces apoptotic and late stage/necrotic cell fractions. The exposure of shear stress potentially plays a role in inhibiting apoptosis activation and TNF-α induced death cascade.
Overall, the apoptosis activity influenced by shear further exhibits a possible connection between shear stress and apoptosis inhibition. The shear stress ultimately decreases overall apoptosis, while DAPK expression is increased. Therefore, DAPK may have a function in other possible mechano-transduction cascades, when endothelial cells are exposed to constant shear. Our data suggests shear stress modulation of DAP-kinase expression and activity, and the potential crosstalk of mechano-transduction and DAPK/apoptosis pathway, may lead to further understanding the responsibility of DAPK in endothelial cell function.

Study of Emotions and Behavioral Intentions in Upscale Restaurants (Management Project)


The physical environment may be an important determinant of customer satisfaction and subsequent behavior when services are consumed primarily for hedonic purposes and customers spend moderate to long periods of time in the physical surroundings. An example of this phenomenon would bein an upscale restaurant setting.
This study explored the domain of the physical environment in an upscale restaurant context to develop a DINESCAPE scale. Relevant literature was reviewed on architecture, environmental psychology, psychology, operations management, and marketing, highlighting empirical and theoretical contributions. Conceptualization and operationalization of the DINESCAPE dimensions is presented, and the procedures used in constructing and refining a multiple-item scale to assess DINESCAPE in an upscale restaurant setting are described. DINESCAPE is a six-factor scale that was developed to measure facility aesthetics, ambience, lighting, service product, layout, and social factors. Evidence of the scale’s reliability, validity, and factor structure is presented, along with potential applications of the scale.
The second phase of the study attempted to build a conceptual model of how the DINESCAPE factors influenced customers’ behavioral intentions through their emotions. The Mehrabian-Russell environmental psychology model was adopted to explore the linkage of the six dimensions of DINESCAPE to customers’ emotional states (pleasure and arousal) and the linkage between pleasure and arousal with customers’ behavioral intentions. Structural equation modeling was used to test the causal relationships among the hypothesized relationships.
Results revealed that facility aesthetics, ambience, and social factors affected the level of customers’ pleasure and ambience and social factors influenced the amount of arousal. In addition, pleasure and arousal had significant effects on subsequent behavioral intentions in the context of upscale restaurant. Finally, implications for restaurateurs and researchers were discussed.

Sunday, October 9, 2011

Development of Model for Large-Bore Engine Cooling Systems (Mechanical Project)


The purpose of this project is to present on the development and results of the cooling system logic tree and model developed as part of the Pipeline Research Council International, Inc (PRCI) funded project at the Kansas State National Gas Machinery Laboratory. PRCI noticed that many of the legacy engines utilized in the natural gas transmission industry were plagued by cooling system problems.
As such, a need existed to better understand the heat transfer mechanisms from the combusting gases to the cooling water, and then from the cooling water to the environment. To meet this need, a logic tree was developed to provide guidance on how to balance and identify problems within the cooling system and schedule appropriate maintenance.
Utilizing information taken from OEM operating guides, a cooling system model was developed to supplement the logic tree in providing further guidance and understanding of cooling system operation. The cooling system model calculates the heat loads experienced within the engine cooling system, the pressures within the system, and the temperatures exiting the cooling equipment. The cooling system engineering model was developed based upon the fluid dynamics, thermodynamics, and heat transfer experienced by the coolant within the system. The inputs of the model are familiar to the operating companies and include the characteristics of the engine and coolant piping system, coolant chemistry, and engine oil system characteristics. Included in the model are the various components that collectively comprise the engine cooling system, including the water cooling pump, aftercooler, surge tank, fin-fan units, and oil cooler.
The results of the Excel-based model were then compared to available field data to determine the validity of the model. The cooling system model was then used to conduct a parametric investigation of various operating conditions including part vs. full load and engine speed, turbocharger performance, and changes in ambient conditions. The results of this parametric investigation are summarized as charts and tables that are presented as part of this thesis.
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Performance evaluation of J2EE & .NET Web Services interacting with a .NET Client (Computer Project)


The objective of this project is to build an e-commerce website using ASP.NET as well as J2EE technologies. Visual Studio 2005 provides a great IDE to build seamless front end layer for the websites with minimum effort. Hence, it is used to build the presentation layer. The business logic layer is developed in ASP.NET 2.0 and J2EE, exposing the functions as web services. Two similar clients have been developed in ASP.NET. These two clients invoke the .NET and J2EE web services.
The two similar websites are subjected to testing for correctness and performance. Stress and load testing is performed thoroughly on the website. A detailed analysis of the results is done using the response times and throughputs from various tests.
This report proves that we can build a website using a presentation tier developed in ASP.NET consuming any of the two technologies’ (ASP.NET & J2EE) web services. This proves to be very useful in scenarios where we need the best overall user experience regardless of the technology, to replace or extend an existing business tier by using a different technology.
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A Real-Time Control System for a Frequency Response-based Permitivity Sensor (Electronics Project)


Permittivity is an important property of dielectric materials. By measuring the permittivity of a material, it is possible to obtain information about the material’s physical and chemical properties, which are of great importance to many applications.
In this study, a realtime control system for a frequency-response (FR) permittivity sensor was developed. The core of the hardware was a kitCON167 microcontroller (PHYTEC America, LLC), which controlled and communicated with peripheral devices. The system consisted of circuits for waveform generation, signal conditioning, signal processing, data acquisition, data display, data storage, and temperature measurement. A C program was developed in the TASKING Embedded Development Environment (EDE) to control the system.
The control system designed in this study embodied improvements over a previously designed version in the following aspects: 1) it used a printed circuit board (PCB); 2) the measurement frequency range was extended from 120 MHz to 400 MHz; 3) the resolution of measured FR data was improved by using programmable gain amplifiers; 4) a data storage module and a real-time temperature measurement module were added to the system; 5) an LCD display and a keypad were added to the system to display the FR data with corresponding frequencies and to allow users to enter commands.
Impedance transformation models for the sensor probe, the coaxial cable that connects the control system with the sensor probe, and the signal processing circuit were studied in order to acquire information on the permittivity of measured materials from measured FR data. Coaxial cables of the same length terminated with different loads, including an open circuit, a short circuit, a 50 resistor, and a 50 resistor paralleled by a capacitor, were tested. The results indicated that the models were capable of predicting the impedances of these specific loads using the FR data. Sensor probes with different sizes and coaxial cables with two different lengths terminated with the same sensor probe were also tested. The results were discussed.
Additional tests for the gain and phase detector were conducted to compare FR data measured by the gain and phase detector with those observed on an oscilloscope. 
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