Reactivation of Limestone-Derived Sorbents using Hydration: Preliminary Results From a Fluidised Bed

A simple method of CO~2~ capture is by using the calcium looping cycle. The calcium looping cycle uses CaCO~3~ as a CO~2~ carrier, via the reversible reaction CaO(s) + CO~2~(g) = CaCO~3~(s), to extract CO2 from the exhaust stream and provide a pure stream of CO~2~ suitable for sequestration. 
A problem associated with the technology is that the capacity of the sorbent to absorb CO~2~ reduces significantly with the number of cycles of carbonation and calcination. The energy penalty of the cycle is considerably increased by cycling unreacted sorbent: hydration of unreactive sorbent has emerged as a promising strategy of reducing this penalty by regenerating the reactivity of exhausted sorbent.
A small atmospheric pressure fluidised bed reactor has been built and tested, that allows repeated cycling between two temperatures up to 1000 °C. 
Work presented here focuses on the effects of variation of the calcination temperature before hydration. Hydration has been found to more than double the reactivity of a spent sorbent cycled under the mildest conditions studied (calcination temperature of 840 °C). However, as calcination temperature is increased the observed reactivation decreases until little reactivation is observed for the sorbent cycled at 950 °C. The primary reason for this appears to be a substantial increase in friability of particles, with reactivity normalised for mass losses appearing similar independent of cycling temperature

Integrated airframe propulsion control

Perturbation equations which describe flight dynamics and engine operation about a given operating point are combined to form an integrated aircraft/propulsion system model. Included in the model are the dependence of aerodynamic coefficients upon atmospheric variables along with the dependence of engine variables upon flight condition and inlet performance. An off-design engine performance model is used to identify interaction parameters in the model. Inclusion of subsystem interaction effects introduces coupling between flight and propulsion variables. To analyze interaction effects on control, consideration is first given to control requirements for separate flight and engine models. For the separate airframe model, feedback control provides substantial improvement in short period damping. For the integrated system, feedback control compensates for the coupling present in the model and provides good overall system stability. However, this feedback control law involves many non-zero gains. Analysis of suboptimal control strategies indicates that performance of the closed loop integrated system can be maintained with a feedback matrix in which the number of non-zero gains is small relative to the number of components in the feedback matrix

Investigating Lifecycle Costs of Optimized Battery-Photovoltaic Systems on a Forward Operating Base

The purpose of this research was to investigate the total life-cycle cost of using utility-scale battery systems to increase the energy efficiency of forward operating bases, thereby reducing the burden of diesel fuel logistics. Specifically, this thesis answered three research questions addressing optimal sizing for various battery types connected with photovoltaic grids, logistical parameters directly impacting total cost, and the cost of increasing the energy resilience of the network. The research questions were answered through a review of literature, modeling, and data analysis. The model determines an optimal size and area for a Vanadium redox flow, Lithium-ion, or Lead-acid battery system, combined with a photovoltaic array, over 5, 10, and 20 years. The optimal Lead-acid battery system was the least expensive, with a 20-year lifecycle system of 142.1 MWh battery and 30.9-acre photovoltaic array costing $13.1M per year. However, after including transportation costs, operations and maintenance, and salvage values, Lithium-ion and Vanadium flow appear to be more cost effective. With a 20-year life-cycle, Lithium-ion and Vanadium redox flow batteries were the most cost-effective option, for the theoretically modeled Alpha forward operating base, with an equivalent annual cost of$24.1M per year and $24.8M per year, respectively. When excluding salvage value from the total cost, both systems cost$25.2M per year and $25.7M per year, respectively. Lead-acid costs for 20 years were$28.4M per year. A breakdown of all costs associated with the final value of each battery system is included in the results. Recommendations on implementation of a battery-photovoltaic system on a forward operating base are discussed. Shortfalls of each technology are also discussed

Excisional treatment of cavernous hemangioma of the liver

Fifteen patients had hepatic hemangiomas removed with liver resections that ranged in extent from local excision to right trisegmentectomy. There was no mortality and little morbidity. The propriety and feasibility of extirpative treatment of such liver tumors has been emphasized by this experience

A shrinking core model for steam hydration of CaO-based sorbents cycled for CO2 capture

Calcium looping is a developing CO2 capture technology. It is based on the reversible carbonation of CaO sorbent, which becomes less reactive upon cycling. One method of increasing the reactivity of unreactive sorbent is by hydration in the calcined (CaO) form. Here, sorbent has been subjected to repeated cycles of carbonation and calcination within a small fluidised bed reactor. Cycle numbers of 0 (i.e., one calcination), 2, 6 and 13 have been studied to generate sorbents that have been deactivated to different extents. Subsequently, the sorbent generated was subjected to steam hydration tests within a thermogravimetric analyser, using hydration temperatures of 473, 573 and 673 K. Sorbents that had been cycled less prior to hydration hydrated rapidly. However, the more cycled sorbents exhibited behaviour where the hydration conversion tended towards an asymptotic value, which is likely to be associated with pore blockage. This asymptotic value tended to be lower at higher hydration temperatures; however, the maximum rate of hydration was found to increase with increasing hydration temperature. A shrinking core model has been developed and applied to the data. It fits data from experiments that did not exhibit extensive pore blockage well, but fits data from experiments that exhibited pore blockage less well

Developing a Template for Logistics Test and Evaluation

Logistics test and evaluation, performed during the developmental test and evaluation effort, is an integral part of the aircraft acquisition process. However, there has been no standard approach to conducting logistics test and evaluation. This study researched past and present approaches to aircraft logistics test and evaluation to determine the most effective method for future programs. We conducted this study using the Delphi method. We solicited the expert opinions of 32 individuals from the logistics test and evaluation field using two rounds of questions. We then statistically analyzed the data to ultimately develop a logistics test and evaluation template. We concluded that the ten ILS elements are indeed a valid baseline for a logistics test and evaluation template, that logistics test and evaluation is worth the resources allocated to it, and that the F-22 logistics test and evaluation approach is the most effective. Logistics test and evaluation, Integrated Logistics Support ILS elements, Developmental test and evaluation

Smart cities need smart villages

© 2018 Economic and Political Weekly. All rights reserved. The current Smart Cities Mission needs to be linked to India's villages. The lacuna in the current mission mandate can be filled by directly addressing the opportunities provided by renewable off-grid production to increase employment and diversification in the rural economy, with a particular focus on India's rural youth.Templeton Foundatio