Letter to William Younger regarding SEAALL letterhead, August 24, 1972

A letter from M. E. Hoover to William Younger regarding proposed changes to an order for SEAALL letterhead

Equivalence of live tree carbon stocks produced by three estimation approaches for forests of the western United States

The focus on forest carbon estimation accompanying the implementation of increased regulatory and reporting requirements is fostering the development of numerous tools and methods to facilitate carbon estimation. One such well-established mechanism is via the Forest Vegetation Simulator (FVS), a growth and yield modeling system used by public and private land managers and researchers, which provides two alternate approaches to quantifying carbon in live trees on forest land – these are known as the Jenkins and Fire and Fuels Extension (FFE) equations. A necessary consideration in developing forest carbon estimates is to address alternate, potentially different, estimates that are likely available from more than one source. A key to using such information is some understanding of where alternate estimates are expected to produce equivalent results. We address this here by focusing on potential equivalence among three commonly employed approaches to estimating individual-tree carbon, which are all applicable to inventory sampling or inventory simulation applications. Specifically, the two approaches available in FVS – Jenkins and FFE – and the third, the component ratio method (CRM) used in the U.S. Forest Service’s, Forest Inventory and Analysis national DataBase (FIADB). A key finding of this study is that the Jenkins, FFE, and CRM methods are not universally equivalent, and that equivalence varies across regions, forest types, and levels of data aggregation. No consistent alignment of approaches was identified. In general, equivalence was identified in a greater proportion of cases when forests were summarized at more aggregate levels such as all softwood type groups or entire variants. Most frequently, the FIA inventory-based CRM and FFE were determined to be equivalent

Parametric Relationships of Conventional Versus Repetitive Loading Triaxial Tests

This investigation was developed to examine response of a field-mixed asphalt-treated granular base material to 100,000 repetitions of a load whose magnitude was determined by a failure criterion proposed by Hoover (1970), and Fish and Hoover (1969). Axial strain and load at the point of maximum volume of a specimen during a conventional triaxial test appear to produce a proportional limit, indicating that failure may have started. Axial stress at this point was applied in the repetitive loading triaxial test at the same confining pressure, during which axial strain and pore pressure continuously increased and specimen volume decreased in each of three series of tests. Post repetitive specimen condition, determined by retesting in the conventional manner indicated that none of the specimens had failed during repetitive loading. Results of this series of tests indicate a further potential feasibility of the use of minimum volume failure criteria for thickness design of a granular base material

Equivalence of live tree carbon stocks produced by three estimation approaches for forests of the western United States

The focus on forest carbon estimation accompanying the implementation of increased regulatory and reporting requirements is fostering the development of numerous tools and methods to facilitate carbon estimation. One such well-established mechanism is via the Forest Vegetation Simulator (FVS), a growth and yield modeling system used by public and private land managers and researchers, which provides two alternate approaches to quantifying carbon in live trees on forest land – these are known as the Jenkins and Fire and Fuels Extension (FFE) equations. A necessary consideration in developing forest carbon estimates is to address alternate, potentially different, estimates that are likely available from more than one source. A key to using such information is some understanding of where alternate estimates are expected to produce equivalent results. We address this here by focusing on potential equivalence among three commonly employed approaches to estimating individual-tree carbon, which are all applicable to inventory sampling or inventory simulation applications. Specifically, the two approaches available in FVS – Jenkins and FFE – and the third, the component ratio method (CRM) used in the U.S. Forest Service’s, Forest Inventory and Analysis national DataBase (FIADB). A key finding of this study is that the Jenkins, FFE, and CRM methods are not universally equivalent, and that equivalence varies across regions, forest types, and levels of data aggregation. No consistent alignment of approaches was identified. In general, equivalence was identified in a greater proportion of cases when forests were summarized at more aggregate levels such as all softwood type groups or entire variants. Most frequently, the FIA inventory-based CRM and FFE were determined to be equivalent

Sustainability in Selleck Food Court at the University of Nebraska-Lincoln

Our project proposes practical solutions for reducing food waste and improving student perceptions of food sustainability at the University of Nebraska-Lincoln (UNL). Our solutions are derived from undergraduate student survey responses and inspired by conversations with UNL Dining and Sustainable campus groups. We collected data from two hundred and six students and focused on students with meal plans who ate at Selleck Food Court. Within the qualitative response field, students could write suggestions for improvements to Selleck Food Court. These responses revealed common themes repeatedly raised by students who are passionate about and interested in dining sustainability, whether that is in recycling options, food waste consciousness, or education. Long-term culture building is valuable in dining to promote students’ sustainable behaviors. As our first main solution, we found that signage can act as a reminder, and influence students to be more conscious. In order for us to gain measurable progress, it takes diligent and routine programming to observe long-term cultural changes in the student population. Our second main solution is for the University of Nebraska-Lincoln to implement composting, specifically at Selleck Food Court. We found that students are already knowledgeable and willing to participate in composting. We acknowledge a limitation of this study was the potential self-selecting bias among the respondents. Our undergraduate student survey was advertised on around 118 bulletin boards within residence halls, within Selleck Food Court, through faculty, some academic buildings from the College of Arts and Sciences and online departmental newsletters. Respondents who are more inclined to participate in sustainable behavior may be more willing to engage in the study than students who feel indifferent towards the topic. Nonetheless, our aim was to broadly collect data and formulate solutions to the food sustainability efforts at Selleck Food Court

Remarks on NonHamiltonian Statistical Mechanics: Lyapunov Exponents and Phase-Space Dimensionality Loss

The dissipation associated with nonequilibrium flow processes is reflected by the formation of strange attractor distributions in phase space. The information dimension of these attractors is less than that of the equilibrium phase space, corresponding to the extreme rarity of nonequilibrium states. Here we take advantage of a simple model for heat conduction to demonstrate that the nonequilibrium dimensionality loss can definitely exceed the number of phase-space dimensions required to thermostat an otherwise Hamiltonian system.Comment: 5 pages, 2 figures, minor typos correcte

Logarithmic oscillators: ideal Hamiltonian thermostats

A logarithmic oscillator (in short, log-oscillator) behaves like an ideal thermostat because of its infinite heat capacity: when it weakly couples to another system, time averages of the system observables agree with ensemble averages from a Gibbs distribution with a temperature T that is given by the strength of the logarithmic potential. The resulting equations of motion are Hamiltonian and may be implemented not only in a computer but also with real-world experiments, e.g., with cold atoms.Comment: 5 pages, 3 figures. v4: version accepted in Phys. Rev. Let

Comment on the calculation of forces for multibody interatomic potentials

The system of particles interacting via multibody interatomic potential of general form is considered. Possible variants of partition of the total force acting on a single particle into pair contributions are discussed. Two definitions for the force acting between a pair of particles are compared. The forces coincide only if the particles interact via pair or embedded-atom potentials. However in literature both definitions are used in order to determine Cauchy stress tensor. A simplest example of the linear pure shear of perfect square lattice is analyzed. It is shown that, Hardy's definition for the stress tensor gives different results depending on the radius of localization function. The differences strongly depend on the way of the force definition.Comment: 9 pages, 2 figure

Notes

Notes by Robert E. Sullivan, Frederick N. Hoover, Robert Lowell Miller, Robert M. Million, F. Gerard Feeney, and James D. Sullivan

On the Geometry and Entropy of Non-Hamiltonian Phase Space

We analyze the equilibrium statistical mechanics of canonical, non-canonical and non-Hamiltonian equations of motion by throwing light into the peculiar geometric structure of phase space. Some fundamental issues regarding time translation and phase space measure are clarified. In particular, we emphasize that a phase space measure should be defined by means of the Jacobian of the transformation between different types of coordinates since such a determinant is different from zero in the non-canonical case even if the phase space compressibility is null. Instead, the Jacobian determinant associated with phase space flows is unity whenever non-canonical coordinates lead to a vanishing compressibility, so that its use in order to define a measure may not be always correct. To better illustrate this point, we derive a mathematical condition for defining non-Hamiltonian phase space flows with zero compressibility. The Jacobian determinant associated with time evolution in phase space is altogether useful for analyzing time translation invariance. The proper definition of a phase space measure is particularly important when defining the entropy functional in the canonical, non-canonical, and non-Hamiltonian cases. We show how the use of relative entropies can circumvent some subtle problems that are encountered when dealing with continuous probability distributions and phase space measures. Finally, a maximum (relative) entropy principle is formulated for non-canonical and non-Hamiltonian phase space flows.Comment: revised introductio