Asymptotic enumeration of incidence matrices

We discuss the problem of counting {\em incidence matrices}, i.e. zero-one matrices with no zero rows or columns. Using different approaches we give three different proofs for the leading asymptotics for the number of matrices with $n$ ones as $n\to\infty$. We also give refined results for the asymptotic number of $i\times j$ incidence matrices with $n$ ones.Comment: jpconf style files. Presented at the conference "Counting Complexity: An international workshop on statistical mechanics and combinatorics." In celebration of Prof. Tony Guttmann's 60th birthda

Climate in the balance

This essay explores how our climate system works, how humans are changing the climate system, and how we might face the challenges of reducing our negative impact on the climate system in the future

Monochromatic knots and other unusual electromagnetic disturbances: light localised in 3D

We introduce and examine a collection of unusual electromagnetic disturbances. Each of these is an exact, monochromatic solution of Maxwell's equations in free space with looped electric and magnetic field lines of finite extent and a localised appearance in all three spatial dimensions. Included are the first explicit examples of monochromatic electromagnetic knots. We also consider the generation of our unusual electromagnetic disturbances in the laboratory, at both low and high frequencies, and highlight possible directions for future research, including the use of unusual electromagnetic disturbances as the basis of a new form of three-dimensional display

Operational Experience from Solar Thermal Energy Projects

Over the past few years, Sandia National Laboratories were involved in the design, construction, and operation of a number of DOE-sponsored solar thermal energy systems. Among the systems currently in operation are several industrial process heat projects and the Modular Industrial Solar Retrofit qualification test systems, all of which use parabolic troughs, and the Shenandoah Total Energy Project, which uses parabolic dishes. Operational experience has provided insight to both desirable and undesirable features of the designs of these systems. Features of these systems which are also relevant to the design of parabolic concentrator thermal electric systems are discussed. Other design features discussed are system control functions which were found to be especially convenient or effective, such as local concentrator controls, rainwash controls, and system response to changing isolation. Drive systems are also discussed with particular emphasis of the need for reliability and the usefulness of a manual drive capability

Relationship between Interplanetary Conditions and Changes in the Geomagnetic Field to Understand the Causes of Geomagnetically Induced Currents

Geomagnetically Induced Currents (GICs) are electrical currents induced in ground-level conductive networks, like power lines and pipelines, which can cause costly damage to infrastructure. GICs are induced in response to fast changes in the geomagnetic field (GMF) according to Faraday’s Law of Electromagnetic Induction. The purpose of this study was to identify the parameters of the solar wind and interplanetary shocks which are most strongly correlated with large, fast changes in the magnitude of the GMF. GMF data is 1-min averaged time series of mid- and high-latitude magnetometer measurements in the Sym/H and AL indices, respectively. For solar wind data, I used an existing database of fast-forward interplanetary shocks compiled from measurements made by the WIND spacecraft. I performed t-tests, and created linear fits to determine which parameter(s) are likely responsible for large 1-min changes in the Sym/H and AL indices. Large changes in Sym/H are most strongly correlated with speed jump at the shock and the change in the square root of dynamic pressure and large changes in AL with speed jump at the shock. To determine the causes of events with larger 1-min changes than the fit, I created a subset of shocks which follow the trend with the same distribution as the outliers to find causes for the outliers. This revealed that faster shock and stronger upstream magnetic field are associated with stronger GMF changes

The New Hampshire Greenhouse Gas Emissions Reduction Fund: Year 3 (July 2011-June 2012) Evaluation

The Greenhouse Gas Emissions Reduction Fund (GHGERF) was created by the New Hampshire legislature in 2008 and has been administered by the New Hampshire Public Utilities Commission (PUC). The purpose of the Fund was to support energy efficiency, energy conservation, and demand response programs to reduce New Hampshire’s greenhouse gas emissions. Funding was derived from the State’s participation in the Regional Greenhouse Gas Initiative (RGGI), a cooperative effort by nine northeastern states to reduce carbon dioxide emissions in the electric power sector via a cap and trade program. As of June 2012, RGGI auctions have resulted in revenues to New Hampshire of $38.7 million, of which$21.8 million had been paid out to grants through June 2012. These funds have been distributed primarily through a competitive grant process administered by the PUC. The total amount of GHGERF grant awards is equal to 0.5% of the $6 billion that New Hampshire spends annually on energy across all sectors. These grants funded a wide variety of projects and programs which directly benefitted New Hampshire homes, schools, businesses, towns, and non-profit organizations. Details for each grant award are available at the PUC’s website. Completed projects supported by GHGERF funds (as of June 2012) have resulted in annual reductions of fossil fuel energy use in NH by 227,400 million BTUs (MMBTUs). Additionally, the GHGERF creates annual energy savings for NH residents and businesses of over$6.7 million and reduces annual carbon dioxide emissions by 22,900 metric tons. Cumulative energy savings due to projects completed as of June 2012 are estimated to be 4.0 million MMBTUs through 2030. NH residents and businesses are expected to save $107.8 million through 2030 based on current energy prices. Carbon dioxide emissions reductions are estimated to be 366,500 metric tons through 2030. In addition to energy reductions, GHGERF has supported energy efficiency workforce development for 700 workers with over 11,300 training hours (as of June 2012). GHGERF has also financially supported almost 2,300 building benchmarking and energy audit evaluations. During the past three years, GHGERF has delivered significant energy savings and served a wide-base of residential, commercial, and industrial energy customers throughout New Hampshire. The experience and capacity built during the three year period allowed GHGERF to deliver the highest amount of energy saved per dollar spent during this past reporting period. The model of having a central specialized expert organization work with multiple energy customers, as seen in all of the grants awarded in 2010, has proven to be a successful one and should be considered as NH’s RGGI program shifts to the NH electric utility energy efficiency programs