CO2 savings from Micro-CHP : influence of operating regimes, demand variations and energy storage

A high temporal precision model was developed to assess the performance of thermal load following micro-CHP system design variants in detail for a number of design days. Carbon savings (relative to a base-case energy system) and prime mover lifetime drivers (thermal cycling and operating duration) were quantified. Novel performance metrics were defined, including Potential Thermal Supply Demand Ratio, and Effective Carbon Intensity of μCHP-Generated Electricity. Significant relative carbon savings were found for design variants with a PTSDR between 0.1-1.5, suggesting that it is a design selection parameter for thermal supply/demand matching. Alternative μCHP operating regimes, restricted seasonal operation, changing thermal demand, fuel and electricity grid carbon intensities, and energy storage (using batteries and hydrogen) were studied. It was found that annual relative carbon savings in excess of 23% were achievable for appropriately-sized design variants, with relatively high electrical efficiency, once a complex control strategy is applied. The control strategy also reduces thermal cycling for the μCHP design variant (versus the Thermal Load Following operating regime), hence increasing prime mover lifetime.Engineering and Physical Sciences Research Council (EPSRC

Creating Community in a Data Science Classroom

A community is a collection of people who know and care about each other. The vast majority of college courses are not communities. This is especially true of statistics and data science courses, both because our classes are larger and because we are more likely to lecture. However, it is possible to create a community in your classroom. This article offers an idiosyncratic set of practices for creating community. I have used these techniques successfully in first and second semester statistics courses with enrollments ranging from 40 to 120. The key steps are knowing names, cold calling, classroom seating, a shallow learning curve, Study Halls, Recitations and rotating-one-on-one final project presentations

EFFECTS OF FIRM-SPECIFIC FACTORS ON R&D EXPENDITURES OF AGRIBUSINESS COMPANIES

The objective of this paper is to determine how the firm's infrastructure, the financial characteristics of a company (net income, sales), and the organizational structure (number of acquisitions, age of establishment of the firm) affect R&D investments in the agricultural sector. We use data for companies under the SIC codes for agricultural chemicals, and crop planning and protection. The results based on analysis of 69 observations of 12 firms revealed that firm's financial and organizational infrastructure does affect its R&D expenditures. Older and larger firms tend to spend more on R&D. During the last 17 years the R&D expenditures with respect to the sales of the company have been reduced. Finally, contrary to the expectations, previous year's profit margins are negatively correlated with the R&D over the sales ratio of the following year.Manufactured Housing; R&D, agriculture, chemicals, crop planning, crop protection, agribusiness, expenditures

Observational Window Functions in Planet Transit Surveys

The probability that an existing planetary transit is detectable in one's data is sensitively dependent upon the window function of the observations. We quantitatively characterize and provide visualizations of the dependence of this probability as a function of orbital period upon several observing strategy and astrophysical parameters, such as length of observing run, observing cadence, length of night, transit duration and depth, and the minimum number of sampled transits. The ability to detect a transit is directly related to the intrinsic noise of the observations. In our simulations of observational window functions, we explicitly address non-correlated (gaussian or white) noise and correlated (red) noise and discuss how these two noise components affect transit detectability in fundamentally different manners, especially for long periods and/or small transit depths. We furthermore discuss the consequence of competing effects on transit detectability, elaborate on measures of observing strategies, and examine the projected efficiency of different transit survey scenarios with respect to certain regions of parameter space.Comment: 16 pages, 11 figures, 8 tables; accepted for publication in Ap

Influence of crystal structure on charge carrier effective masses in BiFeO3_3

Ferroelectric-based photovoltaics have shown great promise as a source of renewable energy, thanks to their in-built charge separation capability, yet their efficiency is often limited by low charge carrier mobilities. In this work, we compare the photovoltaic prospects of various phases of the multiferroic material BiFeO$_3$ by evaluating their charge carrier effective masses using first-principles simulations. We identify a tetragonal phase with the promising combination of a large spontaneous polarisation and relatively light charge carriers. From a systematic study of the octahedral distortions present in BiFeO$_3$, we explain the relationship between structure and effective masses in terms of the changes to the orbital character and overlap at the band edges that result from changes in the geometry. The findings in this study provide some design principles to engineer desired effective masses in BiFeO$_3$ and similar materials through manipulation of their crystal structures in experimentally accessible ways.Comment: 12 pages, 10 figure