Signal and power integrity co-simulation using the multi-layer finite difference method

Mixed signal system-on-package (SoP) technology is a key enabler for increasing functional integration, especially in mobile and wireless systems. Due to the presence of multiple dissimilar modules, each having unique power supply requirements, the design of the power distribution network (PDN) becomes critical. Typically, this PDN is designed as alternating layers of power and ground planes with signal interconnects routed in between or on top of the planes. The goal for the simulation of multi-layer power/ground planes, is the following: Given a stack-up and other geometrical information, it is required to find the network parameters (S/Y/Z) between port locations. Commercial packages have extremely complicated stack-ups, and the trend to increasing integration at the package level only points to increasing complexity. It is computationally intractable to solve these problems using these existing methods. The approach proposed in this thesis for obtaining the response of the PDN is the multi-layer finite difference method (M-FDM). A surface mesh / finite difference based approach is developed, which leads to a system matrix that is sparse and banded, and can be solved efficiently. The contributions of this research are the following: 1. The development of a PDN modeler for multi-layer packages and boards called the the multi-layer finite difference method. 2. The enhancement of M-FDM using multi-port connection networks to include the effect of fringe fields and gap coupling. 3. An adaptive triangular mesh based scheme called the multi-layer finite element method (MFEM) to address the limitations of M-FDM 4. The use of modal decomposition for the co-simulation of signal nets with the PDN. 5. The use of a robust GA-based optimizer for the selection and placement of decoupling capacitors in multi-layer geometries. 6. Implementation of these methods in a tool called MSDT 1.Ph.D.Committee Chair: Madhavan Swaminathan; Committee Member: Andrew F. Peterson; Committee Member: David C. Keezer; Committee Member: Saibal Mukhopadyay; Committee Member: Suresh Sitarama

Enhancing Yield Potential of Hard Red Winter Wheat (Triticum aestivum L.) via Use of Improved Synthetic Backcrosses

Wheat (Triticum aestivum L.) is the most-widely cultivated and third most-produced grain crop in the world. Wheat contributes 19% calories and 21% protein of the global population diet. With an astounding increase in this global population, that is projected to reach 9 billion by 2050, demand for wheat is expected to reach 900 million tons by 2050. However, narrow genetic base and continued pressure from abiotic and biotic stresses pose a tough challenge to achieve the expected increase in grain yield. Research leading to the evolution of synthetic hexaploid wheat (Triticum durum x Aegilops tauschii) and synthetic derived wheat (SDW) (elite bread wheat X synthetic hexaploid wheat) provided a tremendous opportunity to improve wheat production. Preliminary studies showed that SDW had the potential to increase grain yield due to larger seed size and weight. However, heads per square meter and seeds per head are also major determinants of grain yield. Single seed weight was found to be highly heritable in SDW populations in our previous studies. Therefore, we hypothesized that indirectly selecting for heads per square meter and seeds per head, while maintaining single seed weight, will boost yield further. Multi location yield trials were conducted in 2013 and 2014 to determine grain yield and it’s components, morphological traits, resistance to green bug (Schizaphis graminum, Rond), leaf rust (Puccinia triticina), stripe rust (Puccinia striiformis f.sp. Tritici), and powdery mildew (Erysiphe graminis f. sp. Tritici). We estimated quantitative genetic parameters including variance components, heritability, and genetic gain. In addition, we determined response to direct selection and correlated response to an indirect selection using heads per square meter and seeds per head as the indirect selection components. We further estimated the efficiency of indirect selection. Multi-location yield trials indicated certain SDW produced higher grain yield than their recurrent parents and common check varieties. Comparison of the top ten yielding SDW lines mean with the mean of recurrent parents showed SDW lines produced 11.7% higher grain yield than recurrent parents. The SDW lines maintained a similar number of seeds per head and heads per square meter as recurrent parents but had 10% higher single seed weight. Also, SDW showed higher levels of leaf and stripe rust, greenbug, and powdery mildew resistance compared to their recurrent parents. There were certain indications to show that some resistance was transmitted from primary synthetics. Genetic analyses, such as the genotypic coefficient of variation, heritability, and genetic gain showed that there is tremendous scope for grain yield improvement by utilizing SDW. Genetic gain results indicated that grain yield can be improved by 15.6% per cycle at 10% selection intensity (i = 1.76). The efficiency of indirect selection for yield, using heads per meter square, was only 0.41. Similarly, seeds per head and single seed weight had an efficiency of 0.46 and 0.21, respectively. These results indicate that SDW contributed some favorable alleles for yield, biotic stress resistance, and abiotic stress tolerance. These results also showed that SDW contributions were advantageous under both rainfed and irrigated conditions, which makes them an invaluable source for increasing genetic diversity and improving performance of Texas A&M AgriLife wheat germplasm

Implementation Of Transfer Matrix Analysis Of Multi-Section Rotors Using Ansys Parametric Design Language

Critical speed analysis of rotor systems is a difficult process due to the fact that there exists no direct formula to determine the natural frequency of a multi-section rotor. Finite Element packages provide a suitable platform for such an analysis but demand considerable experience on part of the user to perform modeling, meshing, solving and post-processing. The primary objective of this paper is to identify a suitable method for determining rigid bearing critical speeds of multi-section rotors in order to validate the results obtained through traditional FEA package and also to simplify the latter. The only drawback of transfer matrix analysis is the existence of mathematical equations and multiple roots which makes it a cumbersome process by solving manually. This problem has been tackled in this present work through the use of Ansys Parametric Design Language (APDL). The strength of APDL as a macro language have been taken advantage of in this present work to develop an interactive macro which mimics the Finite Element Method and thus relaxes the rigorous routine involved in a traditional tool-based finite element analysis. The results thus obtained through Transfer Matrix Analysis and FEM macro are compared with traditional ANSYS results

Incentive Stackelberg Mean-payoff Games

We introduce and study incentive equilibria for multi-player meanpayoff games. Incentive equilibria generalise well-studied solution concepts such as Nash equilibria and leader equilibria (also known as Stackelberg equilibria). Recall that a strategy profile is a Nash equilibrium if no player can improve his payoff by changing his strategy unilaterally. In the setting of incentive and leader equilibria, there is a distinguished player called the leader who can assign strategies to all other players, referred to as her followers. A strategy profile is a leader strategy profile if no player, except for the leader, can improve his payoff by changing his strategy unilaterally, and a leader equilibrium is a leader strategy profile with a maximal return for the leader. In the proposed case of incentive equilibria, the leader can additionally influence the behaviour of her followers by transferring parts of her payoff to her followers. The ability to incentivise her followers provides the leader with more freedom in selecting strategy profiles, and we show that this can indeed improve the payoff for the leader in such games. The key fundamental result of the paper is the existence of incentive equilibria in mean-payoff games. We further show that the decision problem related to constructing incentive equilibria is NP-complete. On a positive note, we show that, when the number of players is fixed, the complexity of the problem falls in the same class as two-player mean-payoff games. We also present an implementation of the proposed algorithms, and discuss experimental results that demonstrate the feasibility of the analysis of medium sized games.Comment: 15 pages, references, appendix, 5 figure

Sparseland model for speckle suppression of B-mode ultrasound images

Speckle is a multiplicative noise which is inherent in medical ultrasound images. Speckles contributes high variance between neighboring pixels reducing the visual quality of an image. Suppression of speckle noise significantly improves the diagnostic content present in the image. In this paper, we propose how sparseland model can be used for speckle suppression. The performance of the model is evaluated based on variance to mean ratio of a patch in the filtered image. The algorithm is tested on both software generated images and real time ultrasound images. The proposed algorithm has performed similar to past adaptive speckle suppression filters and seems promising in improving diagnostic content

Development of a Modular Unit of a Higher Level Framework or Tool for Basic Programming Course Teaching Through E-Learning Mode

This paper reports about the development of a modular unit of a higher level framework or tool whose intended objective is the creation of animated lessons for basic programming (CS1) course in computer science discipline with visual aids. The goal of such lessons is to address the difficulties faced by the novice programmers in CS1 course.This module here after referred to as ‘type writer’allows instructors to render programmes or code snippets in a live typing manner as opposed to their sudden or en-block placement on the presentation area like a Power Point Slide; a commonly used approach in the present day eLearning.This project is planned to be executed in two stages and ‘type writer’ is the outcome of the first stage. This would be combined with another two modules that are planned to be developed in the second stage, to make the complete tool. The entire tool would be developed in Action Script 3.0 language that works on Adobe Flash Platform