Boundary value problems in stochastic optimal control of advertising

Temporal patterns for advertising include constant spending over time, decreasing spending over time and increasing spending over time. This research shows that all these spending patterns emerge at optimality for the same response function dynamics, due to differences in salvage value assumptions. I use these results to develop a methodology for determining the optimal planning horizon length for each pattern of spending.     

Effect of Si3N4 Addition on Compressive Creep Behavior of Hot‐Pressed ZrB2–SiC Composites

Compressive creep studies have been carried out on hot‐pressed ZrB₂–SiC (ZS) and ZrB₂–SiC–Si₃N₄ (ZSS) composites in air under stress and temperature ranges of 93–140 MPa and 1300°C–1425°C, respectively for time durations of ≈20–40 h. The results of these studies have shown the creep resistance of ZS composite to be greater than that of ZSS. As the temperature is increased from 1300°C to 1425°C, the stress exponent of ZS decreases from 1.7 to 1.1, whereas that of ZSS drops from 1.6 to 0.6. The activation energies for these composites have been found as ≈95 ± 32 kJ/mol at temperatures ≤1350°C, and as ≈470 ± 20 kJ/mol in the range of 1350°C–1425°C. Studies of the postcreep microstructures using scanning and transmission electron microscopy have shown the presence of glassy film with cracks at both ZrB₂ grain boundaries and ZrB₂–SiC interfaces. These results along with calculated values of activation volumes suggest grain‐boundary sliding as the major damage mechanism, which is controlled by O^2? diffusion through SiO₂ at ≤1350°C, and by viscoplastic flow of the glassy interfacial film at temperatures ≥1350°C. Studies by transmission electron microscopy have shown formation of crystalline precipitates of Si₂N₂O near ZrB₂–SiC interfaces in ZSS tested at ≥1400°C, which along with stress exponent values <1 suggests that grain‐boundary sliding involving solution‐precipitation‐type mechanism is operative at these temperatures.     

Toward high‐efficiency dye‐sensitized solar cells with a photoanode fabricated via a simple water‐based formulation

An aqueous formulation containing commercially available P25 nanoparticles and a water‐soluble precursor—titanium (IV) bis(ammonium lactato)dihydroxide (TALH) has been developed and optimized for fabricating photoanodes in dye‐sensitized solar cells. An optimal formulation achieved a power conversion efficiency of 9.2%. Solar cell performance is significantly influenced by precursor concentration impacting the porosity and electron transport of the thin film. The use of TALH during processing is shown to enhance the electron transport in the resulting titanium dioxide nanoparticle network using transient decay measurements. Bridging between neighboring nanoparticles is confirmed using transmission electron microscopy explaining the enhanced electron transport. The developed formulation has several advantages, as it is water‐based, composed of inexpensive, non‐hazardous components, is easy to make, and does not require special handling. The formulation has great potential for industrial applications, in particular for DSC manufacturing using roll‐to‐roll technology. Copyright © 2014 John Wiley & Sons, Ltd.     

Carbon nanotube-zirconium dioxide hybrid for defluoridation of water

This study presents the synthesis of zirconia/multi-walled carbon nanotube (ZrO2/MWCNTs) hybrid as a novel sorbent for water defluoridation. The synthesis was facilitated by the high degree of functionalization of MWCNTs using a microwave assisted process. In the final product, nearly 3% of the carbon atoms were attached to ZrO2. The ZrO2/MWCNTs were effective in fluoride removal and mechanistic aspects of the process are presented. The research findings highlight the potential application for the use of MWCNT hybrids in environmental remediation.     

Analysis of exhaust waste heat recovery from a dual fuel low temperature combustion engine using an Organic Rankine Cycle

This paper examines the exhaust waste heat recovery potential of a high-efficiency, low-emissions dual fuel low temperature combustion engine using an Organic Rankine Cycle (ORC). Potential improvements in fuel conversion efficiency (FCE) and specific emissions (NO_x and CO₂) with hot exhaust gas recirculation (EGR) and ORC turbocompounding were quantified over a range of injection timings and engine loads. With hot EGR and ORC turbocompounding, FCE improved by an average of 7 percentage points for all injection timings and loads while NO_x and CO₂ emissions recorded an 18 percent (average) decrease. From pinch-point analysis of the ORC evaporator, ORC heat exchanger effectiveness (?), percent EGR, and exhaust manifold pressure were identified as important design parameters. Higher pinch point temperature differences (PPTD) uniformly yielded greater exergy destruction in the ORC evaporator, irrespective of engine operating conditions. Increasing percent EGR yielded higher FCEs and stable engine operation but also increased exergy destruction in the ORC evaporator. It was observed that hot EGR can prevent water condensation in the ORC evaporator, thereby reducing corrosion potential in the exhaust piping. Higher ? values yielded lower PPTD and higher exergy efficiencies while lower ? values decreased post-evaporator exhaust temperatures below water condensation temperatures and reduced exergy efficiencies.     

Dynamic control of arabinose and xylose utilization in E. coli

The common bacterium Escherichia coli (E. coli) can utilize the pentose sugars arabinose and xylose for growth and energy. When fed both these sugars, the bacterium preferentially utilizes arabinose and only when all the arabinose is exhausted from the media does it start to use xylose. This hierarchical utilization of the two sugars is dictated by two proteins: AraC and XylR. These proteins act as controllers of sugar utilization and dictate the timing and rate of utilization of these sugars. While the biochemical interactions defining individual arabinose and xylose utilization systems are well understood, it is not completely understood how the hierarchical utilization is maintained by the bacterium, and how the regulatory crosstalk between the two systems facilitates this hierarchy. To help answer these questions, in this work, we systematically experimentally characterize the regulatory crosstalk between the two sugar utilization systems. Our work demonstrates extensive interaction between the two sugar systems. Specifically, data from our experiments suggest that the xylose system can regulate arabinose gene expression and consequently, cellular physiology dynamically via promiscuous transport and maybe through cross interactions between regulator and non‐cognate sugar. Put together, we demonstrate that arabinose and xylose utilization networks exhibit an example of distributed control in a biological system. This design likely ensures that the system does not fail under perturbations (mutations). Our results help understand multi‐process control in biological systems and bring to light design criteria for synthetic biology applications.

     

Design of a Right-Handed Circularly Polarized Printed Antenna for Vehicular Communication

Wireless Personal Communications - In this paper, the authors presented a new fractal microstrip patch antenna for Dedicated Short Range Communication (DSRC) (5.850–5.925 GHz) (IEEE 802.11p)...     

Effect of chemical composition and Co-core size on the magnetic and magneto-transport properties of CoyAg100−y core–shell nanocrystallites

This paper describes the applicability of a modified polyol process in conjunction with a transmetallation reaction in synthesis of Co_yAg_100?y nanocrystallites of a core–shell structure. The substitution Co → Ag is varied as 20 ≤ y ≤ 95 by tuning the microstructure with functional magnetic and giant magneto resistance properties. The existence of core–shell structures was confirmed through transmission electron microscope and the size of Co-core increased from 8 to 50 nm with decrease in Ag-content of the sample. The magnetic behaviour of the sample changed from a pseudo-superparamagnetic nature to ferromagnetic with increase in Co-core size. Normalised saturation magnetisation values increased from 89.5 to 128.6 emu/g with increase in size of Co-core; however, none of the ferromagnetic samples exhibited any magneto resistance (MR). A value of 2.0% MR was observed in case of Co_20.6Ag_79.4 which increased to a maximum of 3.6% MR for Co_36.6Ag_63.4 sample when measured at 5 K.     

Knowledge mining sensory evaluation data: genetic programming, statistical techniques, and swarm optimization

Knowledge mining sensory evaluation data is a challenging process due to extreme sparsity of the data, and a large variation in responses from different members (called assessors) of the panel. The main goals of knowledge mining in sensory sciences are understanding the dependency of the perceived liking score on the concentration levels of flavors’ ingredients, identifying ingredients that drive liking, segmenting the panel into groups with similar liking preferences and optimizing flavors to maximize liking per group. Our approach employs (1) Genetic programming (symbolic regression) and ensemble methods to generate multiple diverse explanations of assessor liking preferences with confidence information; (2) statistical techniques to extrapolate using the produced ensembles to unobserved regions of the flavor space, and segment the assessors into groups which either have the same propensity to like flavors, or are driven by the same ingredients; and (3) two-objective swarm optimization to identify flavors which are well and consistently liked by a selected segment of assessors.     

Biologically important thiols in aqueous extracts of spices and evaluation of their in vitro antioxidant properties

The levels of the biologically important thiols in aqueous extracts of different spices were determined using a sensitive high performance liquid chromatography (HPLC) technique. The spices analysed: turmeric, ginger, cardamom, mustard, fenugreek, and coriander showed different levels of thiols. Biologically important thiols or biothiols measured in these spices included glutathione (GSH), cysteine (CYS), N-acetylcysteine (NAC), homocysteine (HCYS), and γ-glutamyl cysteine (GGC). Our results showed that thiol levels varied from 4 to 1089 nM/g weight (dry or wet). Furthermore, none of the biothiols analysed were found in cumin, nutmeg, clove or star anise. We also studied the antioxidant abilities of these aqueous extracts using various in vitro antioxidant methods to correlate between the levels of these thiols and their antioxidant effects. Our results suggested that antioxidant activities may be independent of thiol content and may be, in part the combination of all the phytochemicals present. These results may be useful in explaining the effect of spices on thiol levels in in vitro and in vivo studies.