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The biotechnological exploitation of microorganisms enables the use of metabolism for the production of economically valuable substances, such as drugs or food. It is, thus, unsurprising that the investigation of microbial metabolism and its regulation has been an active research field for many decades. As a result, several theories and techniques were developed that allow for the prediction of metabolic fluxes and yields as biotechnologically relevant output parameters. One important approach is to derive macrochemical equations that describe the overall metabolic conversion of an organism and basically treat microbial metabolism as a black box. The opposite approach is to include all known metabolic reactions of an organism to assemble a genome-scale metabolic model. Interestingly, both approaches are rather successful at characterizing and predicting the expected product yield. Over the years, macrochemical equations especially have been extensively characterized in terms of their thermodynamic properties. However, a common challenge when characterizing microbial metabolism by a single equation is to split this equation into two, describing the two modes of metabolism, anabolism and catabolism. Here, we present strategies to systematically identify separate equations for anabolism and catabolism. Based on metabolic models, we systematically identify all theoretically possible catabolic routes and determine their thermodynamic efficiency. We then show how anabolic routes can be derived, and we use these to approximate biomass yield. Finally, we challenge the view of metabolism as a linear energy converter, in which the free energy gradient of catabolism drives the anabolic reactions. [ABSTRACT FROM AUTHOR]

This paper numerically simulates the vortex-induced vibrations of ocean current energy harvester with attached spinning cylinders by using the embedded iterative immersed boundary method.The variations of the hydrodynamic properties(the root-mean-square lift coefficient CL,rms,the mean and root-mean-square drag coefficient CD,mean and CD,rms,and the maximum non-dimensional vibration amplitude Ymax/D) with the energy harvest damping ratio ζharness,the non-dimensional spinning velocity α and azimuthal angle θ of the attached cylinders are investigated.Moreover,the variations of the maximum non-dimensional vibration amplitude Ymax/D with the combined parameter α/θ are further investigated.A set of formula is presented by using the curve fitting method.The variations of the coefficients in the formula with influencing parameters are discussed qualitatively. [ABSTRACT FROM AUTHOR]

Abstract Current narrative on biofuels is backed up by a large number of studies published in the scientific literature that address second-generation bioethanol only through a single topic approach, nonetheless in the vast majority of cases transition to this energy carrier is evaluated as a generally 'promising' technology. This paper presents a first attempt in proposing an integrated evaluation of the actual benefits expected from bioethanol in the transport sector, by applying the Multi-Scale Integrated Analysis of Societal and Ecosystem Metabolism (MuSIASEM) to the prospective realization of a local system of bio-refinery in Campania Region (Southern Italy). MuSIASEM is a multi-criteria analysis enabling to deal with the complexity of a territorial energy system. Since the unavoidable intrinsic uncertainty, the study does not focus on predictions, but adopts a strategy of Quantitative Story-Telling about some relevant results underlying the limits and critical issues about the energy converter fabric, the economic profitability, environmental constraints and the questionable concept of marginal land. The findings suggest concluding toward falsification of key points in the current narrative: (i) the system is not an efficient solar energy converter; (ii) it fails to realize many of the expectations for a renewable energy carrier producer; (iii) the contribution to decarbonization strategies is not as high as desired and other environmental impacts could not be neglected; (iv) the very large land requirement is hardly compatible with conversion of truly marginal land in Campania region; (v) compared to alternate land uses it does not seem an actually promising strategy to regain value from rural economy. Graphical abstract Image 1 Highlights • Single topic studies are not useful for comprehension of a territorial biorefinery. • Multi-scale and multi-dimensional approach to face the ambiguity of energy concept. • Performance's comparison of two distinct energy production systems is misleading. • Decarbonization and marginal lands concepts are a simplification of the problem. [ABSTRACT FROM AUTHOR]

The application of high-temperature superconducting (HTS) equipment faces challenges that thick current leads connecting superconducting devices with external power sources will generate huge thermal load loss and the difficulty in persistent current operation for a long period. In this work, we have proposed the mechanism of a novel mechanically operated HTS energy converter based on the electromagnetic coupling of the permanent magnet and the HTS coil. The proposed HTS energy converter can charge and discharge a closed superconducting coil without electrical contact, and convert mechanical energy to electromagnetic energy efficiently. However, its working mechanism is theoretically controversial, as it seems to violate Lenz's law. An analytical method based on the method of equivalent circuit is proposed to explain its working mechanism and replicate all experimental electrical behaviour of the HTS energy converter. Experimental results have verified the theoretical analysis. The proposed mechanically operated HTS energy converter is easily controllable, making it promising in various of applications, including superconducting magnetic energy storage (SMES), high field magnets, energy harvesting of urban rail transportation and electromagnetic propulsion. • An analytical model is proposed to explain the phenomenon seeming against Lenz's law. • A novel wireless HTS energy converter with promising applications is proposed. • Factors that could affect working performance of the proposed device are discussed. • Experiments were carried out to verify the proposed analytical model. [ABSTRACT FROM AUTHOR]

A gate driver with efficient energy recovery based on bidirectional buck/boost converter is proposed. The proposed gate‐drive circuit is constructed by power supply, energy storage module and energy converter. Instead of discharging directly in conventional gate drivers, gate charge Qg in the proposed gate driver is released to the storage capacitor during turning‐off transition of power MOSFET. Principle of the proposed gate driver is analysed, and design consideration of key parameters are also suggested. The gate‐drive losses of the proposed gate driver and resonant gate driver are, respectively, tested as 0.102 and 0.125 W at 100 kHz. The test result proves that power consumption of the proposed gate driver is significantly decreased. [ABSTRACT FROM AUTHOR]

• Dual-pump confluence achieves easily the power aggregation. • Dual-pump confluence reduces operating pressure while motor speed is kept constant. • The operating pressure depends not only on load but on the turbine shaft speed. • Distributed HST system can be applied to deep-sea by aggregating dispersed energy. It is well known that generating electricity in the deep-sea has always been a very challenging problem. Aiming at the power demand of the underwater observation system, this paper presents a novel distributed ocean current energy hydrostatic transmission (HST) power generation solution, which can generate electricity efficiently and continuously in large depth and low flow velocity environment. The proposed solution adopts a dual-pump confluence design. According to this, the working pressure of the HST is reduced to avoid overflow compared to the single pump design, and therefore the dispersed micro-energy in deep-sea can be aggregated together to convert continuously to active power rather than to the heat. Furthermore, the solution employs an energy-saving strategy involving constant pressure pump and seawater cooling and improves effectively the efficiency to some extent. Besides, it was found that the working pressure of the system depends not only on load torques but also on turbine speeds reversely, while the speed of hydraulic variable displacement motor maintains constant. Therefore, dual-pump confluence implies power aggregation and plays a key role in generating electricity in deep-sea. Simulation results and the tests based on the 5 kW prototype verifies the feasibility of the proposed distributed HST solution. Accordingly, at the current status, the distributed HST power generation is the most probable solution applied to the deep ocean. [ABSTRACT FROM AUTHOR]

Vortex-induced oscillations offer a potential means to harness hydrokinetic energy even at low current speeds. In this study, we consider a novel converter where a cylinder undergoes angular oscillations with respect to a pivot point, in contrast to most previous configurations, where the cylinder undergoes flow-induced oscillations transversely to the incident free stream. We formulate a theoretical model to deal with the coupling of the hydrodynamics and the structural dynamics, and we numerically solve the resulting nonlinear equation of cylinder motion in order to assess the performance of the energy converter. The hydrodynamical model utilizes a novel approach where the fluid forces acting on the oscillating cylinder are split into components acting along and normal to the instantaneous relative velocity between the moving cylinder and the free stream. Contour plots illustrate the effects of the main design parameters (in dimensionless form) on the angular response of the cylinder and the energy efficiency of the converter. Peak efficiencies of approximately 20% can be attained by optimal selection of the main design parameters. Guidelines on the sizing of actual converters are discussed. [ABSTRACT FROM AUTHOR]