Transient analysis and synthesis of linear circuits using constraint logic programming

In this paper describes the design of a transient analysis program for linear circuits and its implementation in a Constraint Logic Programming language, CLP(R). The transient analysis program parses the input circuit description into a network graph, analyses its semantic correctness and then performs the transient analysis. The test results show that the program is at least 97% accurate when run at two decimal places. We have also compared the performance of our program with a commercial package implemented in an imperative language. The advantages of implementing the analysis program in a CLP language include: quick construction and ease of maintenance. We also report on the synthesis of generation of a circuit with given transient characteristics

Logic Programming approaches for routing fault-free and maximally-parallel Wavelength Routed Optical Networks on Chip (Application paper)

One promising trend in digital system integration consists of boosting on-chip communication performance by means of silicon photonics, thus materializing the so-called Optical Networks-on-Chip (ONoCs). Among them, wavelength routing can be used to route a signal to destination by univocally associating a routing path to the wavelength of the optical carrier. Such wavelengths should be chosen so to minimize interferences among optical channels and to avoid routing faults. As a result, physical parameter selection of such networks requires the solution of complex constrained optimization problems. In previous work, published in the proceedings of the International Conference on Computer-Aided Design, we proposed and solved the problem of computing the maximum parallelism obtainable in the communication between any two endpoints while avoiding misrouting of optical signals. The underlying technology, only quickly mentioned in that paper, is Answer Set Programming (ASP). In this work, we detail the ASP approach we used to solve such problem. Another important design issue is to select the wavelengths of optical carriers such that they are spread across the available spectrum, in order to reduce the likelihood that, due to imperfections in the manufacturing process, unintended routing faults arise. We show how to address such problem in Constraint Logic Programming on Finite Domains (CLP(FD)). This paper is under consideration for possible publication on Theory and Practice of Logic Programming.Comment: Paper presented at the 33nd International Conference on Logic Programming (ICLP 2017), Melbourne, Australia, August 28 to September 1, 2017. 16 pages, LaTeX, 5 figure

Chlorpyrifos Removal for Wastewater Reuse

Approximately 1.2 billion people around the world live in areas of physical water scarcity. This could increase to half of the world’s population by 2030 and could displace 24 to 700 million people unless steps are taken to ensure adequate water supply.1 Water scarcity is an escalating issue within the United States, specifically in Western inland states with arid climates. This scarcity is encouraging communities to investigate tertiary level municipal wastewater treatment, allowing for reuse of wastewater. Unfortunately, wastewater contains numerous contaminants that are not regulated by the Environmental Protection Agency (EPA) under the Safe Drinking Water Act (SDWA). Many of these contaminants are endocrine disrupting compounds (EDCs). According to the European Union Commission, an endocrine disruptor is “an exogenous substance that causes adverse health effects in an intact organism, or its progeny, in consequence to the induced changes in endocrine functions.”2 Many EDCs are not completely removed by standard secondary wastewater treatment methods. With the growing demand for potable water, as well as water for irrigation and agricultural purposes, communities are having to evaluate the potential health risks due to EDCs and other unregulated compounds. The Woo-Pig-Sewage team selected one unregulated contaminant, chlorpyrifos(CLP), to test. CLP is an organophosphate insecticide that is commonly used residentially and commercially. CLP has a long term impact asa cholinesterase inhibitor in humans.3 Using traditional biological methods, CLP, as well as other pesticides, are nearly impossible to remove.4 CLP is on the Fourth Unregulated Contaminant Monitoring Rule list produced by the EPA to provide a basis for future regulation.5 A bench scale unit utilizing ozone treatment (O3), ultraviolet radiation (UV), and granular activated carbon (GAC) was constructed to remove this contaminant from dopednanopure water. Ultimately, the selected technologies will be able to treat secondary wastewater effluent from the wastewater treatment plant (WWTP) in Tucumcari, New Mexico for direct or indirect aquifer reintroduction. Direct aquifer reintroduction would involveinjection of water to the existing aquifer, whileindirect aquifer introduction would consist of introducing treated effluent to an existing canal system. An oxidation process paired with UV and GAC filtration can be utilized to remove EDCs such as CLP and other unregulated contaminants from wastewater. O3is extremely effective at oxidizing bacteria as well as other organic molecules. UV is also a commonly used method to degrade organic compounds and is currently being used at the WWTP in Tucumcari, New Mexico and in Fayetteville, Arkansas. GAC is utilized to remove trace amounts of contaminants from wastewater streams, usually as a final treatment before the water is reintroduced to the environment. The WWTP in Rio Rancho, New Mexicocurrently plans to utilize GAC filtration in this manner. The Woo-Pig-Sewage team performed experiments to determine if the combination of O3, UV, and GAC could reduce CLP to a concentration below the minimum detection limit of 0.001ppm. To test the effectiveness of the bench scale, caffeine was used as an organic tracer. Bench scale results indicate that the proposed system is effective in the removal of caffeine and CLP from doped water samples. Caffeine concentrations were reduced to below the minimum detection limit of 0.05 ppm for samples with initial concentrations ranging from 0.1 ppm to 10 ppm. CLP was reduced to below the minimum detection limit of 0.001ppm from and initial concentration of 0.1 ppm. An industrial scale process was sized based on treating secondary effluent from the WWTP in Tucumcari, NM. The total cost was determined to be an additional $2.31 per 1000 gallons, assuming 0$4.95 per 1000 gallons for the existing treatment paired with the proposed system. While this adds a significant cost to the existing treatment at the WWTP in Tucumcari, plants with larger flow rates would see significantly less of an increase in the total cost per 1000 gallons. This can be seen from the comparison of the 144,000gallonper day (gpd) system with existing UV treatment and the 300,000gpdTucumcari system also utilizing UV treatment. The 144,000gpdsystem was estimated to cost about 60% more per 1000 gallons. However, if the Tucumcari WWTP is awarded a grant to cover 100% of the Fixed Capital Investment (FCI), the proposed system would only increase the cost per 1000 gallons by 38%. If the EPA determines that EDCs such as CLP must be removed from the effluent of WWTPs, a process such as the one proposed by the Woo-Pig-Sewage team will be necessary

Machine analysis of students' mathematical representations for multiplication and division problems

Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (page 35).This project extends Classroom Learning Partner classroom interaction software to include a semantic interpretation component. This semantic interpretation, combined with existing syntactic interpretation, enables the software to tag and group student work using knowledge of the math used in both creating and solving problems. The analysis is being prototyped using student work in grades 4 and 5, with focus on multiplication and division. First, during the authoring step, the notebook author gives each page a "page definition" that encapsulates the mathematical problem presented on that page. For a multiplication or division problem, this involves setting the three numbers connected by the product relation (e.g., 6 * 3 = 18), marking which of those numbers are given by the problem or otherwise unknown, and selecting an overall context for the problem, such as equal groups or area. Then, once students have submitted their work, the analysis component takes the raw output of the syntactic interpretation step and relates it back to the mathematical content of the page to assign each student's work a set of automatically generated tags. These tags address the correctness of a student's methods and results, as well as highlighting different problem-solving strategies that students might have used to arrive at the same answer. Finally, the teacher can sort student submissions by these various tags to quickly find noteworthy or contrasting examples to present to the class.by Matthew Peairs.M. Eng

Solving ptychography with a convex relaxation

Ptychography is a powerful computational imaging technique that transforms a collection of low-resolution images into a high-resolution sample reconstruction. Unfortunately, algorithms that are currently used to solve this reconstruction problem lack stability, robustness, and theoretical guarantees. Recently, convex optimization algorithms have improved the accuracy and reliability of several related reconstruction efforts. This paper proposes a convex formulation of the ptychography problem. This formulation has no local minima, it can be solved using a wide range of algorithms, it can incorporate appropriate noise models, and it can include multiple a priori constraints. The paper considers a specific algorithm, based on low-rank factorization, whose runtime and memory usage are near-linear in the size of the output image. Experiments demonstrate that this approach offers a 25% lower background variance on average than alternating projections, the current standard algorithm for ptychographic reconstruction.Comment: 8 pages, 8 figure