Very Low Temperature Electronic Transport in Al-Pd-Re Quasicrystalline Alloys

Electrical resistivities of two icosahedral (I) Al-Pd-Re alloys have been measured between room temperature and mK temperatures. One quasicrystalline (QC) polygrain Al-Pd-Re sample exhibited insulating behavior in its resistivities, increasing by a factor of r=R(4 K)/R(300 K)=7.76; its room temperature resistivity was 9,890 μΩ cm. A “phenomenological” expression fitted the conductivity data well between 300 K to 0.5 K. Below 0.4 K a crossover to an activated variable-range hopping law was observed. Low temperature magnetoresistance ratio data and fits using the wave function shrinkage theory are presented. A second QC Al-Pd-Re sample had a small resistance temperature ratio r=2.12. The room temperature resistivity was extremely large, ρ(300 K)≈40,980 μΩ cm. Its conductivity could be described well using a simple temperature power law between 300 K to 20 K. Below 20 K there was a crossover to a new behavior. Below 1 K, the conductivity could be fitted using a very weakly insulating power law where σ(T)≈11.37T ^0.032 in (Ω cm)⁻¹, suggesting that this sample is located just below the metal-insulator transition. The magnetoconductivity data could not be fitted successfully using the 3D weak localization (WL) theory and inserting into it physical and realistic fitting magnitudes for the inelastic magnetic field B _in.      

Numerical Modeling of Biomass Pyrolysis—Heat and Mass Transport Models

We consider the pyrolysis of robinia pseudoacacia, which is a common material for biomass gasifiers. We formulate three models of the process, with increasingly detailed physics, best suited for different spatial scales from large to small. For each model, we perform numerical simulations of adaptable complexity and compare the results with the thermogravimetric analysis (TGA) experiments.     

Structure and cyclic oxidation resistance of Pt, Pt/Pd-modified and simple aluminide coatings on CMSX-4 superalloy

The coatings were prepared by the means of Pt and Pt/Pd galvanizing, followed by vapor phase aluminizing at 1050 °C. Microstructural and phase analysis revealed that all the investigated coatings consisted mainly of β-NiAl phase, however the Pt-modified aluminide coating also contained PtAl₂ phase and pure platinum precipitates. The cross-sectional microstructure of the coatings was zonal and composed of β-NiAl phase zone and the diffusion zone. The Pt modified aluminide coating's cross-section also incorporated an outermost zone consisting of β-NiAl and PtAl₂ phases. The concentration profiles proved that both Pt and Pd contents decrease gradually inwards the modified coatings. Cyclic oxidation tests at 1100 °C proved that Pt/Pd-modified aluminide coatings exhibit the best performance under cyclic conditions. The analysis of oxidation kinetics curves showed that the course of simple aluminide coating's oxidation is slightly different from that of Pt- and Pt/Pd-modified aluminide coatings.     

Energy Cost Burdens for Low-Income and Minority Households

Abstract

Problem, research strategy, and findings: Of the three primary components of housing affordability measures—rent, transportation, and utilities—utility costs are the least understood yet are the one area where the cost burden can be reduced without household relocation. Existing data sources to estimate energy costs are limited to surveys with small samples and low spatial and temporal resolution, such as the American Housing Survey and the Residential Energy Consumption Survey. In this study, we present a new method for small-area estimates of household energy cost burdens (ECBs) that leverages actual building energy use data for approximately 13,000 multifamily properties across five U.S. cities and links energy costs to savings opportunities by analyzing 3,000 energy audit reports. We examine differentials in cost burdens across household demographic and socioeconomic characteristics and analyze spatial, regional, and building-level variations in energy use and expenditures. Our results show the average low-income household has an ECB of 7%, whereas higher income households have an average burden of 2%. Notably, even within defined income bands, minority households experience higher ECBs than non-Hispanic White households. For lower income households, low-cost energy improvements could reduce energy costs by as much as $1,500 per year.

Takeaway for practice: In this study we attempt to shift the focus of energy efficiency investments to their impact on household cost burdens and overall housing affordability. Our analysis explores new and unique data generated from measurement-driven urban energy policies and shows low-income households disproportionately bear the burden of poor-quality and energy-inefficient housing. Cities can use these new data resources and methods to develop equity-based energy policies that treat energy efficiency and climate mitigation as issues of environmental justice and that apply data-driven, targeted policies to improve quality of life for the most vulnerable urban residents.     

Seasonal Changes Affect Root Prunasin Concentration in <Emphasis Type="Italic">Prunus serotina</Emphasis> and Override Species Interactions between <Emphasis Type="Italic">P. serotina</Emphasis> and <Emphasis Type="Italic">Quercus petraea</Emphasis>

The allocation of resources to chemical defense can decrease plant growth and photosynthesis. Prunasin is a cyanogenic glycoside known for its role in defense against herbivores and other plants. In the present study, fluctuations of prunasin concentrations in roots of Prunus serotina seedlings were hypothesized to be: (1) dependent on light, air temperature, and humidity; (2) affected by competition between Prunus serotina and Quercus petraea seedlings, with mulching with Prunus serotina leaves; (3) connected with optimal allocation of resources. For the first time, we determined prunasin concentration in roots on several occasions during the vegetative season. The results indicate that seasonal changes have more pronounced effects on prunasin concentration than light regime and interspecific competition. Prunus serotina invested more nitrogen in the synthesis of prunasin under highly restricted light conditions than in higher light environments. In full sun, prunasin in roots of Prunus serotina growing in a monoculture was correlated with growth and photosynthesis, whereas these relationships were not found when interspecific competition with mulching was a factor. The study demonstrates that prunasin concentration in Prunus serotina roots is the result of species-specific adaptation, light and temperature conditions, ontogenetic shift, and, to a lesser extent, interspecific plant-plant interactions.     

Dynamics of the guideway system founded on casting compound

The work presents a new technology for the assembly of ball guideway systems which involves the use of a thin layer of a casting compound. The experimentally verified simulation research presented in the work indicates that the use of the casting compound between the guide rail and the bed of the machine tool positively influences the dynamics of the system. The paper is concerned with the comparison between the new solution with the guide rail assembly technology presently in use on the basis of a guideway system consisting of a body and a milling table. The dynamics was compared with the use of a frequency response function which had been determined in an impulse test. The proposed solution is characterised by a higher dynamic stiffness, which may directly influence the precision of the machined surfaces.     

Estimating Water Retention in Post-mining Excavations Using LiDAR ALS Data for the Strzelin Quarry,in Lower Silesia

A digital terrain model of the Strzelin granite quarry was created from ISOK project data obtained from airborne laser scanning (ALS). Based on 2009, 2012, and 2014 data, the volume of water in the Strzelin quarry’s two excavations were determined. Additionally, the predicted volume of retained water after mining ceases was calculated, assuming a water level of 150.0 m a.s.l. In 2014, the two reservoirs retained, respectively, ≈?0.14 and 0.01 million m³ of water. If the two pits are eventually connected, ≈?6.6 million m³ of water could be retained. Including the 2014 water volume as a small-scale retention basin would increase the volume of retained water in the ?l?za catchment and Strzelin County by 19.0%, and 34.2%, respectively. The hypothetical reservoir created after mining ends would increase small-scale (reservoir and pond) retention?≈?8 times in the ?l?za catchment and ≈?15 times in the County, constituting a significant improvement.     

Ductility assessment of two-chord composite steel-concrete battened columns

The ductility of a column is one of the most important characteristics of a structure subjected to unexpected overloads, load reversals, blast loads or dynamic impacts. Structural ductile members are capable of dissipating large amounts of energy by undergoing large deformations before failure, hence providing early warning to the occupants of the building. Previous analyses conducted by the authors suggest that, in addition to the type of column (steel, reinforced concrete and composite steel–concrete), the applied measure of ductility as well as other factors (the materials used and the loading and boundary conditions) have a significant influence on a column’s ductility. This paper proposes a new approach to the analysis of the ductility of columns. This approach distinguishes between the column’s pre-peak, post-peak and total ductility, and develops ductility parameters based on the displacement and energy for each of these ductility types. Based on experimental and numerical research on two-chord composite steel–concrete columns subjected to vertical monotonic loads, the influence of concrete strength and batten plate spacing on the columns’ vertical ductility is evaluated. It is concluded that designing two-chord composite steel–concrete columns to have small batten plate spacing and a relatively low concrete strength class can maximise the vertical ductility.