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Maximum Power Output (maximum + power_output)
Selected AbstractsUndulatory fish swimming: from muscles to flowFISH AND FISHERIES, Issue 2 2006Ulrike K. Müller Abstract Undulatory swimming is employed by many fish for routine swimming and extended sprints. In this biomechanical review, we address two questions: (i) how the fish's axial muscles power swimming; and (ii) how the fish's body and fins generate thrust. Fish have adapted the morphology of their axial musculature for high power output and efficiency. All but the superficial muscle fibres are arranged along curved trajectories, and the myomeres form nested cones. Two conflicting performance goals shape the fibre trajectories of the axial muscles. Maximum power output requires that all fibres contract uniformly. In a bending fish, uniform contraction in a single myomere can be ensured by curved fibre trajectories. However, uniform strain is only desirable if all muscle fibres have the same contractile properties. The fish needs several muscle-fibre types that generate maximum power at different contraction speeds to ensure effective muscle power generation across a range of swimming speeds. Consequently, these different muscle-fibre types are better served by non-uniform contractions. High power output at a range of swimming speeds requires that muscle fibres with the same contractile properties contract uniformly. The ensuing helical fibre trajectories require cone-shaped myomeres to reduce wasteful internal deformation of the entire muscle when it contracts. It can be shown that the cone-shaped myomeres of fish can be explained by two design criteria: uniform contraction (uniform strain hypothesis) and minimal internal deformation (mechanical stability hypothesis). So far, only the latter hypothesis has found strong support. The contracting muscle causes the fish body to undulate. These body undulations interact with the surrounding water to generate thrust. The resulting flow behind the swimming fish forms vortex rings, whose arrangement reflects the fish's swimming performance. Anguilliform swimmers shed individual vortex rings during steady swimming. Carangiform swimmers shed a connected chain of vortex rings. The currently available sections through the total flow fields are often not an honest representation of the total momentum in the water , the wake of carangiform swimmers shows a net backward momentum without the fish accelerating , suggesting that our current picture of the generated flow is incomplete. To accelerate, undulatory swimmers decrease the angle of the vortex rings with the mean path of motion, which is consistent with an increased rate of backward momentum transfer. Carangiform swimmers also enlarge their vortex rings to accelerate and to swim at a higher speed, while eel, which are anguilliform swimmers, shed stronger vortex rings. [source] New Stack Design of Micro-tubular SOFCs for Portable Power SourcesFUEL CELLS, Issue 6 2008T. Suzuki Abstract Micro-tubular solid oxide fuel cells (SOFCs) have high thermal stability and higher volumetric power density, which are considered to be ideal features for portable power sources and auxiliary power units for automobile. Here, we report a new stack design using anode supported micro-tubular SOFCs with 2,mm diameter using Gd doped CeO2 (GDC) electrolyte, NiO-GDC anode and (La, Sr)(Co, Fe)O3 (LSCF)-GDC cathode. The new stack consists of three bundles with five tubular cells, sealing layers and interconnects and fuel manifolds. The performance of the stack whose volume is 1,cm3 was shown to be 2.8,V OCV and maximum power output of 1.5,W at 500,°C, applying air only by natural convection. The results also showed strong dependence of the fuel flow rates on the stack performance, which was correlated to the gas diffusion limitation. [source] Investigation of the anti-fungal activity of coptisine on Candida albicans growth by microcalorimetry combined with principal component analysisJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2009W.-J. Kong Abstract Aims:, This study investigated the anti-fungal activity of coptisine on Candida albicans growth. Methods and Results:, The metabolic power-time curves of Candida albicans growth at 37°C affected by coptisine were measured by microcalorimetry using an LKB-2277 Bioactivity Monitor with stop-flow mode. Then, the diameter of inhibitory zones in the agar layer was observed using agar cup method, and the minimal inhibitory concentration (MIC) of coptisine on Candida albicans growth was determined by serial dilution method. From the principal component analysis on nine quantitative parameters obtained from the power-time curves, we could easily evaluate the anti-fungal activity of coptisine by analysing the change of values of the main two parameters, growth rate constant k and maximum power output in the log phase Pm, log. The results showed that coptisine had strong anti-fungal activity: at a low concentration (45 ,g ml,1) began to inhibit the growth of Candida albicans and at a high concentration (500 ,g ml,1) completely inhibited Candida albicans growth. Coptisine gave big inhibitory zones with diameters between 11 and 43 mm within test range, and the MIC of it was 1000 ,g ml,1. Conclusions:, Coptisine had strong anti-fungal activity on Candida albicans growth. The method of microcalorimetry applied for the assay of anti-fungal activity of coptisine was quantitative, sensitive and simple. Significance and Impact of the Study:, This work will provide useful information for the development of chemical biology policy in the use of anti-microbials in food and drug production. [source] Micro-fabrication and monitoring of three-dimensional microstructures based on laser-induced thermoplastic formationMICROSCOPY RESEARCH AND TECHNIQUE, Issue 10 2009Leyan Wang Abstract This article reports a novel laser-induced micro-fabrication method and its monitoring system for three-dimensional (3D) microstructures. The mechanism of the method is that a small zone of thermoplastic material melted by laser heating grows in liquid surrounding environment, solidifying into a convex microstructure, such as micro-dot or micro-pillar. A laser diode (808 nm) with maximum power output of 130 mW is used as power source, and a kind of paraffin mixed with stearic acid and paint serves as the thermoplastic material for 3D microstructure formation experiments. A light microscope system consisting of a charge-coupled device (CCD) and a computer is utilized to realize real-time observation of the micro-fabricating process. The distribution of local temperature rise on material surface created by laser irradiation is simulated. The effects of liquid environment on microstructure formation have been theoretically analyzed and experimentally studied. Experiments are further carried out to investigate the relationship between laser spot and fabricated microstructures. The results indicate that the widths of micro-dots or micro-pillars are mostly determined by the size of focal spot, and their heights increase with the enlargement of laser power density. With this method, a micro-dot array of Chinese characters meaning "China" has been successfully fabricated through computer programming. This method has the advantages of implementing direct, mask-less, real-time and inexpensive 3D microstructure fabrication. Therefore, it would be widely applied in the fields of micro/nano-technology for practical fabrication of different kinds of 3D microstructures. Microsc. Res. Tech., 2009. © 2009 Wiley-Liss, Inc. [source] Treatment of cow-waste slurry by a microbial fuel cell and the properties of the treated slurry as a liquid manureANIMAL SCIENCE JOURNAL, Issue 6 2006Hiroshi YOKOYAMA ABSTRACT Resource recycling and the proper treatment of animal waste to reduce its environmental impact are currently important issues for the livestock industry. A microbial fuel cell (MFC), a new type of bioreactor, is expected to play roles in both waste-water purification and energy recovery. However, the generation of electricity from cow waste has not yet been examined. In this study, using an MFC, we examined the possibility of generating electricity from dairy-cow waste slurry, and analyzed the properties of the treated slurry as liquid manure for resource recycling. The MFC treatment of the slurry generated electricity in a dose-dependent manner, and the maximum power output by the MFC from a 1 g of chemical oxygen demand/L slurry was 0.34 mW/m2. After the MFC treatment, 84% of the biological oxygen demand in the slurry was removed and three essential fertilizer elements (nitrogen, phosphorus, and potassium) were retained at 84, 70, and 91% levels, respectively. The amount of ammonia nitrogen in the slurry, as an element of fast-release fertilizer, was increased by 1.9-fold. Although the treated slurry displayed properties that made it preferable as liquid manure, further studies to improve the electrical power output by the MFC are required for practical use. [source] | ||||||||||