Model Predictive Control of a Wave Energy Converter with Discrete Fluid Power Power Take-Off System

Wave power extraction algorithms for wave energy converters are normally designed without taking system losses into account leading to suboptimal power extraction. In the current work, a model predictive power extraction algorithm is designed for a discretized power take of system. It is shown how the quantized nature of a discrete fluid power system may be included in a new model predictive control algorithm leading to a significant increase in the harvested power. A detailed investigation of the influence of the prediction horizon and the time step is reported. Furthermore, it is shown how the inclusion of a loss model may increase the energy output. Based on the presented results it is concluded that power extraction algorithms based on model predictive control principles are both feasible and favorable for use in a discrete fluid power power take-off system for point absorber wave energy converters

Experimental Validation of Mathematical Framework for Fast Switching Valves used in Digital Hydraulic Machines

A prototype of a fast switching valve designed for a digital hydraulic transmission has been manufactured and experimentally tested. The valve is an annular seat valve composed of a plunger connected with a direct electromagnetic moving coil actuator as the force producing element. Based on an elaborate optimization method the valve is designed to maximize the efficiency of a digital hydraulic motor targeted to a wind turbine transmission system. The optimisation method comprises a mathematical framework which predicts a valve switching time of approximately 1 ms with a peak actuator input power of 10 kW during switching (mean of approximately 250 W) and a pressure loss below 0.5 bar at 600 l/min. The main goal of this article is validate parts of the mathematical framework based on a series of experiments. Furthermore, this article aims to document the experience gained from the experimental work and to study and assess a moving coil actuators suitability for the application.</jats:p

Dissection of the antimicrobial and hemolytic activity of Cap18: Generation of Cap18 derivatives with enhanced specificity

<div><p>Due to the rapid emergence of resistance to classical antibiotics, novel antimicrobial compounds are needed. It is desirable to selectively kill pathogenic bacteria without targeting other beneficial bacteria in order to prevent the negative clinical consequences caused by many broad-spectrum antibiotics as well as reducing the development of antibiotic resistance. Antimicrobial peptides (AMPs) represent an alternative to classical antibiotics and it has been previously demonstrated that Cap18 has high antimicrobial activity against a broad range of bacterial species. In this study we report the design of a positional scanning library consisting of 696 Cap18 derivatives and the subsequent screening for antimicrobial activity against <i>Y</i>. <i>ruckeri</i>, <i>A</i>. <i>salmonicida</i>, <i>S</i>. Typhimurium and <i>L</i>. <i>lactis</i> as well as for hemolytic activity measuring the hemoglobin release of horse erythrocytes. We show that the hydrophobic face of Cap18, in particular I13, L17 and I24, is essential for its antimicrobial activity against <i>S</i>. Typhimurium, <i>Y</i>. <i>ruckeri</i>, <i>A</i>. <i>salmonicida</i>, <i>E</i>. <i>coli</i>, <i>P</i>. <i>aeruginosa</i>, <i>L</i>. <i>lactis</i>, <i>L</i>. <i>monocytogenes</i> and <i>E</i>. <i>faecalis</i>. In particular, Cap18 derivatives harboring a I13D, L17D, L17P, I24D or I24N substitution lost their antimicrobial activity against any of the tested bacterial strains. In addition, we were able to generate species-specific Cap18 derivatives by particular amino acid substitutions either in the hydrophobic face at positions L6, L17, I20, and I27, or in the hydrophilic face at positions K16 and K18. Finally, our data showed the proline residue at position 29 to be essential for the inherent low hemolytic activity of Cap18 and that substitution of the residues K16, K23, or G21 by any hydrophobic residues enhances the hemolytic activity. This study demonstrates the potential of generating species-specific AMPs for the selective elimination of bacterial pathogens.</p></div

Multilingual signs for Latin American residents in a local town in Japan : Findings based on fieldwork in Minokamo city

Analysis of a Selected Set of Antimicrobial Peptides The rapid emergence of resistance to classical antibiotics has increased the interest in novel antimicrobial compounds. Antimicrobial peptides (AMPs) represent an attractive alter-native to classical antibiotics and a number of different studies have reported antimicrobial activity data of various AMPs, but there is only limited comparative data available. The mode of action for many AMPs is largely unknown even though several models have sug-gested that the lipopolysaccharides (LPS) play a crucial role in the attraction and attach-ment of the AMP to the bacterial membrane in Gram-negative bacteria. We compared th