Pattern measurements of a low-sidelobe horn antenna

The power pattern of a corrugated horn antenna designed for low sidelobes was measured to levels 90 dB below the main beam maximum in both theE- andH-planes. The measured patterns were found to be in good agreement with theoretical predictions.     

Robust supply chain performance via Model Predictive Control

This paper presents a novel robust Model Predictive Control (MPC) method for real-time supply chain optimization under uncertainties. This method optimizes the closed-loop economic performance of supply chain systems and addresses different sources of uncertainties located external to and within the feedback loop. The future system behavior is predicted by a closed-loop model, which includes both the open-loop system model and a controller model described by an optimization problem. The robust MPC formulation involves the solution of a constrained, bi-level stochastic optimization problem, which is transformed into a tractable problem involving a limited number of deterministic conic optimization problems solved reliably using an interior point method. The robust controller is applied to a real industrial multi-echelon supply chain optimization problem, and its performance is shown to reduce stock-outs without excessive inventories.     

Operations optimization and control design for a petroleum distillation process

Process automation involves both steady-state optimization and feedback control. In this paper, the economic optimum steady-state operating conditions for a petroleum crude distillation process are determined using a tray-to-tray model. This model is used to evaluate the steady-state operation achieved with several multivariable process control designs. Only one controller design was found to result in essentially optimum steady-state operation; others deviated significantly. The method applied in this paper relies on a knowledge of the key disturbances occurring in the process; good economic performance may not be obtained should other disturbance types occur. The results demonstrate the importance of implementing the operations optimization through a control strategy which will respond properly to disturbances.     

Models for Managing Contingency Construction Operations

A contingency is a crisis situation such as a national disaster, civil disorder, or military invasion that creates a major threat to the safety and security of a population. Essentially all contingencies require construction support that is generally mission critical and inherently challenging due to the dynamics and uncertainty with the availability of resources and the demands for the projects. This paper considers a military contingency for which all construction projects must be completed within a fixed time to achieve mission success. The effectiveness in accomplishing the construction mission is based on mission time reliability assessed using the probability of interference between load measured in the number of days required for the project, and the capacity which is taken as the available allotted resources. Two models are developed to assist in managing the allocation of resources for the construction operations; one based on conditions of moderate risk with randomly occurring repetitive loads, and the other a Markov chain model for high risk conditions. Examples are provided.     

Engineering Saccharomyces cerevisiae for next generation ethanol production

Conversion of cellulose, hemicellulose or starch to ethanol via a biological route requires enzymatic conversion of these substrates to monosaccharides that can be assimilated by a fermenting organism. Consolidation of these events in a single processing step via a cellulolytic or amylolytic microorganism(s) is a promising approach to low‐cost production of fuels and chemicals. One strategy for developing a microorganism capable of such consolidated bioprocessing (CBP) involves engineering Saccharomyces cerevisiae to expresses a heterologous enzyme system enabling (hemi)cellulose or starch utilization. The fundamental principle behind consolidated bioprocessing as a microbial phenomenon has been established through the successful expression of the major (hemi)cellulolytic and amylolytic activities in S. cerevisiae. Various strains of S. cerevisiae were subsequently enabled to grow on cellobiose, amorphous and crystalline cellulose, xylan and various forms of starch through the combined expression of these activities. Furthermore, host cell engineering and adaptive evolution have yielded strains with higher levels of secreted enzymes and greater resistance to fermentation inhibitors. These breakthroughs bring the application of CBP at commercial scale ever closer. This mini‐review discusses the current status of different aspects related to the engineering of S. cerevisiae for next generation ethanol production. © 2013 Society of Chemical Industry     

Complex radio frequency (RF) communications with virtual pulses

A novel complex pulse forming technique has been developed using ultra wideband (UWB) frequency concepts where multiple carriers are modulated by the pulse width of the primary signal source. Specialized modulation of the pulse train provides an effective communication medium with inherent advantages of an UWB system. The multiple frequency nature of the non-traditional “pulse” formation provides a means of implementing UWB without the necessity of complex pulse formation of the classical UWB. The particular example of the research implemented in this paper allows explicit user choice of the specific UWB frequencies, e.g., ISM frequencies, to avoid current restrictions of the Federal Communications Commission (FCC). The reported method also contains an implicit property to support secure information transmission to receivers at known distances.The objective of this technique is an easy to form communication pulse having UWB low energy advantages along with the freedom of implementation without license requirements from regulating authorities, while adhering to the set limits of intentional radiators. The method chosen in this case was based on having the sum of energies from multiple frequencies remain within the restricted radiation limits at the correlated receiver. Included in the implementation technique is the inclusion of the signal fading effect as part of the modulation technique. The relevance of this pulse forming technique is in the simplicity of spreading the transmitted power among multiple frequencies without the issue of decay factor in the current methods. The result presented gives two sets of relative amplitudes of the transmitted frequencies identifying the transmitted character, e.g., 0 or 1. A form of amplitude encryption, due to the RF signal fading effect was also presented as advantage in the technique.     

Hydrodynamics and recovered papers deinking in an ozone flotation column

This work was aimed at investigating the potential use of ozone flotation for recovered papers deinking. The mixing characteristics and the bubble size of a Venturi aerated laboratory flotation column were studied in the presence of simplified model systems and of an industrial pulp slurry. Experimental results showed that surfactants dissolved in the pulp slurry stabilized air bubbles while cellulose fibers promoted coalescence. Moreover, bubble buoyancy was sufficient to fluidize the fiber suspension generating perfect mixing. The gas–liquid transfer coefficient of ozone (k_La) estimated from gas hold-up, air bubble size and k_La measured in water was high enough (0.84 1/s) for the complete transfer of ozone in the pulp slurry and the generation of ozone-free gas effluent. With O₃ dosage of 0.8 mg O₃/mg COD, ozone flotation allowed increasing chemical oxygen demand removal from 41 to 63% with no effect on the ink flotation efficiency, which remained close to that obtained with air flotation, i.e. ～92%.     

Alienation and exploratory behavior.

Tested the hypothesis that attitudes of alienation inhibit intrinsically motivated exploration of an unfamiliar but ordinary environment. 29 university students completed measures including the Alienation Test and the Maudsley Personality Inventory, and their exploratory behavior was observed during a mock waiting period. Stepwise multiple regression confirmed the hypothesis. Additional analyses indicate that nihilism and adventurousness were the most inhibitory types of alienation. The most inhibitory interpersonal contexts were alienation from social institutions, other persons, and the self. The adaptive disadvantage of alienation attitudes is noted. (42 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)