Infrared Signature of Novel Super-Thermite (Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>/Mg) Fluorocarbon Nanocomposite for Effective Countermeasures of Infrared Seekers

Infrared (IR) guided missiles are real threat; they caused 90% of aircraft damage. Fluorocarbon polymer nanocomposite based on super-thermites can offer superior thermal signature to countermeasure IR guided missile seekers. This study reports on the sustainable fabrication of mono-dispersed colloidal Fe₂O₃ nanoparticles with 3 nm average particle size. Fe₂O₃ nanoparticles were dispersed in acetone for subsequent integration in fluorocarbon polymer. The impact of Fe₂O₃ content on thermal signature was evaluated using (FT-MIR 2–6 μm) spectrophotometer. Nanocomposite polymer with 8 wt% Fe₂O₃ offered an increase in the average intensity of α (2–3 μm) and β (4–5 μm) bands by 50 and 85% respectively to that of reference formulation. Quantification of stimulated emitting species in the combustion flame was conducted using ICT thermodynamic code. The developed nanothermite particles extended the primary reaction zone by 183%. Full discussions about combustion zones with associated exothermic chemical reactions have been represented.     

Efficiency Enhancement of Single‐Walled Carbon Nanotube‐Silicon Heterojunction Solar Cells Using Microwave‐Exfoliated Few‐Layer Black Phosphorus

Carbon nanotube‐silicon (CNT‐Si)‐based heterojunction solar cells (HJSCs) are a promising photovoltaic (PV) system. Herein, few‐layer black phosphorus (FL‐BP) sheets are produced in N‐methyl‐2‐pyrrolidone (NMP) using microwave‐assisted liquid‐phase exfoliation and introduced into the CNTs‐Si‐based HJSCs for the first time. The NMP‐based FL‐BP sheets remain stable after mixing with aqueous CNT dispersion for device fabrication. Due to their unique 2D structure and p‐type dominated conduction, the FL‐BP/NMP incorporated CNT‐Si devices show an impressive improvement in the power conversion efficiency from 7.52% (control CNT‐Si cell) to 9.37%. Our density‐functional theory calculation reveals that lowest unoccupied molecular orbital (LUMO) of FL‐BP is higher in energy than that of single‐walled CNT. Therefore, we observed a reduction in the orbitals localized on FL‐BP upon highest occupied molecular orbital to LUMO transition, which corresponds to an improved charge transport. This study opens a new avenue in utilizing 2D phosphorene nanosheets for next‐generation PVs.     

Synthesis,Characterization, and Evaluation of Ethoxylated Lauryl-Myrisityl Alcohol Nonionic Surfactants as Wetting Agents,Anti-Foamers,and Minimum Film Forming Temperature Reducers in Emulsion Polymer Lattices

Two nonionic FAEO (fatty alcohol ethoxylated) surfactants with varying solubility were obtained by the reaction of lauryl-myrisityl alcohol (LMA) with ethylene oxide to yield lauryl-myristyl/alcohol ethoxylated with 3 and 31 mol of ethylene oxide by changing the length of polyethylene glycol segment. The prepared surfactants, designated as LMAEO-3 and LMAEO-31, were characterized for their structures using spectroscopic measurements; in addition, their surface properties were investigated. The results indicated that LMAEO-31 exhibits excellent surface activity. Evaluation of the surfactants as wetting agents, anti-foamers, and minimum film forming temperature (MFFT) reducer in emulsion polymer lattices achieved promising results indicating high performance in the mentioned industrial applications.     

Online model-based diagnosis to support autonomous operation of an advanced life support system

This article describes methods for online model-based diagnosis of subsystems of the advanced life support system (ALS). The diagnosis methodology is tailored to detect, isolate, and identify faults in components of the system quickly so that fault-adaptive control techniques can be applied to maintain system operation without interruption. We describe the components of our hybrid modeling scheme and the diagnosis methodology, and then demonstrate the effectiveness of this methodology by building a detailed model of the reverse osmosis (RO) system of the water recovery system (WRS) of the ALS. This model is validated with real data collected from an experimental testbed at NASA JSC. A number of diagnosis experiments run on simulated faulty data are presented and the results are discussed.     

Feasibility study of a solar-assisted heating/cooling system for an aquatic centre in hot and humid climates

This paper reports on a feasibility study of a solar-powered heating/cooling system for a swimming pool/space combination in a tropical environment. The system utilizes an absorption chiller and a cooling tower to meet the facilities and locker room load. The heating is accomplished by employing hot water generated by heat exchange with the solar collector working fluid. Two thermal storage tanks were employed for the collector and domestic use. The absorption chiller utilizes hot water to regenerate the LiBr solution. The proposed system enables the swimming season to be extended from sixteen weeks to fifty-two weeks. Simulation results indicate that a combination of a double glazed collector area of 600–4800 m² and a storage tank volume of 11·36 m³ results in a 25–37% reduction in the consumption of natural gas. Economic analysis is performed based on the life-cycle-cost method and takes into account the effects of discount rate, fuel price and fuel inflation rate. Different scenarios for which the solar-assisted system is economical are presented and analysed. © 1997 John Wiley & Sons, Ltd.     

Empirical heat transfer and frost thickness correlations during frost deposition on a cylinder in cross-flow in the transient regime

This paper reports on results of an experimental investigation where the emphasis was placed on obtaining empirical correlations for the frost thickness–time history and the heat transfer coefficient–time history for a cylinder in humid air cross-flow. The facility employed for the investigation consisted of a low-velocity wind tunnel comprised of a rectangular test section, a transition section and a honeycomb placed at the tunnel entrance. An external refrigerator was used to cool an antifreeze solution having a mixture of 90% methanol and 10% ethylene glycol. Measured parameters included, among other things, the heat transfer coefficient as well as the frost thickness. © 1998 John Wiley & Sons, Ltd.     

Thermal analysis of roof-spray cooling

Roof-spray cooling systems have been developed and implemented to reduce the heat gain through roofs so that conventional cooling systems can be reduced in size or eliminated. Currently, roof-spray systems are achieving greater effectiveness due to the availability of direct digital controls (DDC). The objective of this paper is to develop a mathematical model for the heat transfer though a roof-spray cooled roof that predicts heat transfer based on existing weather data and roof heat transfer characteristics as described by the transfer function method (TFM). The predicted results of this model are compared to the results of existing experimental data from previously conducted roof-spray cooling experiments. The mathematical model is based on energy balances at the exterior and interior surfaces of the roof construction that include evaporative, convective, radiative, and conductive heat transfer mechanisms. The transfer function method is used to relate the energy balances at the two surfaces that differ in amplitude and phase due to the thermal resistance and thermal capacitance characteristics of the roof. The model is shown to yield relatively good predictions of heat transfer rates through the roof. The calculation method shows promise as a relatively simple means of predicting heat gains based on calculation procedures that are similar to those frequently used by practicing engineers. © 1998 John Wiley & Sons, Ltd.     

A feasibility study of steam-jet refrigeration

In this paper a feasibility study of steam-jet refrigeration is conducted. First and second law analyses as well as the economics of a steam-jet refrigeration system are presented. Thermodynamic parameters investigated include the coefficient of performance (COP), refrigerating effect, condenser heat rejection, motive steam requirements, second law efficiency, and system irreversibility. Economic parameters investigated include equipment costs, space needs, power requirements, and installed and operational costs. © 1998 John Wiley & Sons, Ltd.