A Characterisation of Optimal Channel Assignments for Cellular and Square Grid Wireless Networks

In this paper we first present a uniformity property that characterises optimal channel assignments for networks arranged as cellular or square grids. Then, we present optimal channel assignments for cellular and square grids; these assignments exhibit a high value for δ₁ – the separation between channels assigned to adjacent stations. We prove an upper bound on δ₁ for such optimal channel assignments. This upper bound is greater than the value of δ₁ exhibited by our assignments. Based on empirical evidence, we conjecture that the value our assignments exhibit is a tight upper bound on δ₁.     

Effect of Sintering Temperature and Atmosphere on Nonlubricated Sliding Wear of Nano-Yttria-Dispersed and Yttria-Free Duplex and Ferritic Stainless Steel Fabricated by Powder Metallurgy

The nonlubricated sliding wear behavior of nano-yttria-dispersed and yttria-free duplex and ferritic stainless steel against a diamond tip was studied. The stainless steel samples were fabricated by a conventional powder metallurgy route in which nano-yttria-dispersed and yttria-free duplex and ferritic stainless steel powders were cold compacted and then conventionally sintered at either 1000, 1200, or 1400°C in an argon atmosphere. For comparison, another set of samples was sintered at 1000°C in a nitrogen atmosphere. The wear behavior of sintered stainless steel samples against a diamond indenter was investigated using a pin-on-disc apparatus at 10 and 20 N loads and at a constant speed of 0.0041 m/s. It is proposed that yttria-dispersed stainless steels showed higher wear resistance compared to yttria-free stainless steel due to their improved hardness and density. Stainless steel sintered in a nitrogen atmosphere exhibited better wear resistance than those sintered in an argon atmosphere due to the formation of hard and brittle Cr₂N. The wear mechanisms of stainless steels against diamond were found to be mainly abrasive and oxidative. Semiquantitative analysis of the worn surfaces and wear debris confirmed the occurrence of oxidation processes during wear.     

Role of flow cytometry for the improvement of bioprocessing of oleaginous microorganisms

Oleaginous microorganisms, such as yeast, fungi, microalgae and bacteria, represent a key segment of second generation feed-stock materials and are considered to synthesize a wide range of industrially important chemical compounds. Oleaginous microorganisms possess a broad varieties of chemical compounds such as carotenoids, pigments, carbohydrates, chlorophyll, and storage-material lipids. Oleaginous microorganisms have been recognized as promising sources for the synthesis of unsaturated, especially polyunsaturated fatty acids (PUFA). So far, a variety of high-throughput screening methodologies (HTMs) have been employed for the development of bioprocessing of oleaginous microorganisms for sustainable production of industrially valuable compounds. Of HTMs, flow cytometry (FC) and sorters (FACS) have received substantial interest as better HTMs because of their ability to screen large numbers of cells within seconds, and interrogate and isolate living cells at single-cell level. Forward and side scattering signals of FC are used to determine the physiological state of the cell while different channels available in the FC facilitate the detection of signals produced from fluorophores. Simultaneous measurement of physiological characteristics along with specific compound accumulation at single-cell level enables the possibility of separating a particular phenotype with specific properties from a population. Different microbial strain development strategies in combination with FACS produced improved phenotypes with desired properties. This review first summarizes the FACS methodologies suitable for oleaginous microorganisms and the significant progress that has been achieved in oleaginous microorganisms using FACS, and highlights the important, advanced and future prospects of FACS methodologies that are suitable for the development of bioprocessing in oleaginous microorganisms. © 2018 Society of Chemical Industry     

Effect of Aluminum Content on Infrared Characteristics of BaF2/ThQ-Containing Glasses

The incorporation of large amounts of aluminum substantially alters the ir characteristics of BaF₂/ThF₄-based glasses. In particular, a distinct peak associated with aluminum is observed in the fundamental reflectivity spectrum at ∼ 625 cm⁻¹, with a concomitant shift of the ir absorption edge to higher frequencies. Although beneficial for glass formation, the addition of aluminurn has a deleterious effect on the ir transparency range of heavy-metal, fluoride glasses.     

Missing Data Imputation for Time-Frequency Representations of Audio Signals

With the recent attention towards audio processing in the time-frequency domain we increasingly encounter the problem of missing data within that representation. In this paper we present an approach that allows us to recover missing values in the time-frequency domain of audio signals. The presented approach is able to deal with real-world polyphonic signals by operating seamlessly even in the presence of complex acoustic mixtures. We demonstrate that this approach outperforms generic missing data approaches, and we present a variety of situations that highlight its utility.     

Optical properties of density-disordered solids

A statistical theory of the optical response in solids with a small degree of microscopic density disorder is formulated, in which the properties of the disordered solid are related to those of its crystalline counterpart. Both the electronic and lattice response are treated, by determining the changes in band structure and phonon spectrum as functions of local density. As an application of the theory, we deduce the optical properties of amorphous semiconductors such as Si, Ge, GaAs and InAs and compare them to those of their crystalline counterparts. Good agreement with experiment is obtained for the predicted optical and infrared absorption spectra, and for the Raman scattering spectrum. The analysis provides a quantitative gauge of the departure from crystallinity in the optical spectrum, i.e., the relative contribution of processes which do not conserve crystal momentum. National Research Council Postdoctoral Resident Research Associate at AFCRL. Supported in part by Air Force Cambridge Research Labora-tories (AFSC), Contract No. F19628-72-C-0286     

Model-based real-time whole building energy performance monitoring and diagnostics

Building energy systems often consume approximately 16% more energy [Mills, E. 2011. “Building Commissioning: A Golden Opportunity for Reducing Energy Costs and Greenhouse Gas Emissions in the United States.” Energy Efficiency 4 (2): 145–173] than is necessary due to system deviation from the design intent. Identifying the root causes of energy waste in buildings can be challenging largely because energy flows are generally invisible. To help address this challenge, we present a model-based, real-time whole building energy diagnostics and performance monitoring system. The proposed system continuously acquires performance measurements of heating, ventilation and air-conditioning, lighting and plug equipment usage and compare these measurements in real-time to a reference EnergyPlus model that either represents the design intent for the building or has been calibrated to represent acceptable performance. A proof-of-concept demonstration in a real building is also presented.