Matrix Factorizations, Minimal Models and Massey Products

We present a method to compute the full non-linear deformations of matrix factorizations for ADE minimal models. This method is based on the calculation of higher products in the cohomology, called Massey products. The algorithm yields a polynomial ring whose vanishing relations encode the obstructions of the deformations of the D-branes characterized by these matrix factorizations. This coincides with the critical locus of the effective superpotential which can be computed by integrating these relations. Our results for the effective superpotential are in agreement with those obtained from solving the A-infinity relations. We point out a relation to the superpotentials of Kazama-Suzuki models. We will illustrate our findings by various examples, putting emphasis on the E_6 minimal model.Comment: 32 pages, v2: typos corrected, v3: additional comments concerning the bulk-boundary crossing constraint, some small clarifications, typo

Bench- and pilot-scale evaluation of mercury speciation measurement methods

The 1990 Clean Air Act Amendments require the US Environmental Protection Agency (EPA) to assess the health risks associated with mercury. Since the rate of mercury deposition and the type of control strategies used may depend on the type of mercury species emitted, a proven sampling method that can reliably and accurately speciate mercury at the very low concentrations found in coal combustion flue gas is necessary. A number of mercury speciation methods have been proposed, including wet-chemistry methods, such as EPA Method 29, the Ontario Hydro method, and the tris-buffer method, as well as dry methods such as the Mercury Speciation Absorption method (MESA). In addition, a number of companies are developing continuous emissions monitors to speciate mercury by difference. Bench- and pilot-scale tests, sponsored by the Electric Power Research Institute (EPRI) and the US Department of Energy (DOE), are currently under way at the Energy and Environmental Research Center (EERC) to determine the most accurate and precise mercury speciation method available. The overall objective of the test program is to determine whether EPA Method 29 or other sampling methods can reliably quantify and speciate mercury in flue gas from coal-fired boilers at both the inlet and outlet of a particulate control device such as a pulse-jet baghouse. A specific goal of the project is to determine the precision and bias of the various mercury speciation methods as a function of process variables

Algorithmic deformation of matrix factorisations

Branes and defects in topological Landau-Ginzburg models are described by matrix factorisations. We revisit the problem of deforming them and discuss various deformation methods as well as their relations. We have implemented these algorithms and apply them to several examples. Apart from explicit results in concrete cases, this leads to a novel way to generate new matrix factorisations via nilpotent substitutions, and to criteria whether boundary obstructions can be lifted by bulk deformations.Comment: 30 page

Pulse-jet baghouse performance improvement with flue gas conditioning

A pilot study was conducted at the Energy and Environmental Research Center (EERC) at the University of North Dakota to evaluate the effectiveness of flue gas conditioning in reducing tube sheet pressure drop and fine particulate emissions from a pulse-jet fabric filter. The project was jointly funded by the US Department of Energy (DOE), the Electric Power Research Institute (EPRI), and the Canadian Electrical Association (CEA). The work was completed with EERC facilities consisting of a pulverized coal-fired combustor and pilot baghouse. Full-scale pulse-jet bags were employed under conditions similar to large-scale baghouses. The investigation included baseline tests and tests in which ammonia and SO[sub 3] were, injected upstream of the baghouse to determine the effect of conditioning on baghouse performance. The primary independent variables included coal type, conditioning agent concentrations, air-to-cloth (A/C) ratio, and fabric type. The main dependent variables were particulate emissions, bagbouse pressure drop, and cohesive properties of the fly ash. Results demonstrated significant benefits of using conditioning with a pulse-jet baghouse, including a substantial reduction in particulate emissions and a substantial reduction in pressure drop (or the ability to operate at a higher A/C ratio without increasing pressure drop or bag-cleaning frequency). The improvements in fabric filter performance correlate strongly with a shift in the tensile strength and with increases in the aerated and packed porosity of the fly ash. Conditioning appears to be applicable to a wide range of coals and fabrics. Applications for this technology are where there is a need to reduce pressure drop and/or particulate emissions in existing bagbouses, to reduce fine-particle air toxic emissions which may be required in the future, and for new bagbouse installations to allow operation at a higher A/C ratio while providing an ultrahigh fine-particle collection efficiency

Enhanced flue gas conditioning study

Many electrostatic precipitators (ESPS) do not achieve acceptable particulate removal efficiencies because of high-resistivity ash. One method to improve ESP performance is to employ chemical conditioning agents to reduce fly ash resistivity. Widely used agents include sulfur trioxide (SO[sub 3]) and ammonia, which are sometimes used simultaneously. For some fly ashes, that have a low affinity for SO[sub 3], conditioning with SO[sub 3] alone is not adequate to reduce resistivity without excessive amounts of SO[sub 3] exiting the stack. In such cases, the use of ammonia in addition to SO[sub 3] may reduce the amount of required SO[sub 3] and prevent the emission of excess SO[sub 3] out of the stack. The general objective of the work was to test enhanced flue gas conditioning methods to improve the performance of ESPS. Specific objectives were to (1) verify the relationship between the required SO[sub 3] injection rates to maintain the desired fly ash resistivity and temperature for four coals, (2) verify that dual conditioning with both ammonia and SO[sub 3] promotes SO[sub 3] utilization and allows for resistivity modification with moderate SO[sub 3] injection rates, and (3) verify the effectiveness and practicality of an enhanced flue gas conditioning (EFGC) method. The EFGC method is a proprietary development of Wahlco, Inc

Pulse-jet baghouse performance improvement with flue gas conditioning

A pilot study was conducted at the Energy and Environmental Research Center (EERC) at the University of North Dakota to evaluate the effectiveness of flue gas conditioning in reducing tube sheet pressure drop and fine particulate emissions from a pulse-jet fabric filter. The project was jointly funded by the US Department of Energy (DOE), the Electric Power Research Institute (EPRI), and the Canadian Electrical Association (CEA). The work was completed with EERC facilities consisting of a pulverized coal-fired combustor and pilot baghouse. Full-scale pulse-jet bags were employed under conditions similar to large-scale baghouses. The investigation included baseline tests and tests in which ammonia and SO{sub 3} were, injected upstream of the baghouse to determine the effect of conditioning on baghouse performance. The primary independent variables included coal type, conditioning agent concentrations, air-to-cloth (A/C) ratio, and fabric type. The main dependent variables were particulate emissions, bagbouse pressure drop, and cohesive properties of the fly ash. Results demonstrated significant benefits of using conditioning with a pulse-jet baghouse, including a substantial reduction in particulate emissions and a substantial reduction in pressure drop (or the ability to operate at a higher A/C ratio without increasing pressure drop or bag-cleaning frequency). The improvements in fabric filter performance correlate strongly with a shift in the tensile strength and with increases in the aerated and packed porosity of the fly ash. Conditioning appears to be applicable to a wide range of coals and fabrics. Applications for this technology are where there is a need to reduce pressure drop and/or particulate emissions in existing bagbouses, to reduce fine-particle air toxic emissions which may be required in the future, and for new bagbouse installations to allow operation at a higher A/C ratio while providing an ultrahigh fine-particle collection efficiency