Interactive effects of light, nitrogen source, and carbon dioxide on energy metabolism in the diatom Thalassiosira pseudonana

Due to the ongoing effects of climate change, phytoplankton are likely to experience enhanced irradiance, more reduced nitrogen, and increased water acidity in the future ocean. Here, we used Thalassiosira pseudonana as a model organism to examine how phytoplankton adjust energy production and expenditure to cope with these multiple, interrelated environmental factors. Following acclimation to a matrix of irradiance, nitrogen source, and CO2 levels, the diatom's energy production and expenditures were quantified and incorporated into an energetic budget to predict how photosynthesis was affected by growth conditions. Increased light intensity and a shift from inline image to inline image led to increased energy generation, through higher rates of light capture at high light and greater investment in photosynthetic proteins when grown on inline image. Secondary energetic expenditures were adjusted modestly at different culture conditions, except that inline image utilization was systematically reduced by increasing pCO2. The subsequent changes in element stoichiometry, biochemical composition, and release of dissolved organic compounds may have important implications for marine biogeochemical cycles. The predicted effects of changing environmental conditions on photosynthesis, made using an energetic budget, were in good agreement with observations at low light, when energy is clearly limiting, but the energetic budget over-predicts the response to inline image at high light, which might be due to relief of energetic limitations and/or increased percentage of inactive photosystem II at high light. Taken together, our study demonstrates that energetic budgets offered significant insight into the response of phytoplankton energy metabolism to the changing environment and did a reasonable job predicting them.

Multiphase transformer-coupled converter: two different strategies for energy conversion

The operation of a multiphase topology, ideally, without energy storage presents the advantage of achieving very high efficiency over a wide load range as well as a fast dynamic response. However, ideal no-energy storage operation also implies a limitation in the regulation capability of the topology, the output voltage can only take discrete values. These features (high efficiency and discrete regulation capability) of the proposed energy conversion strategy enable the topology as a candidate for `DC-DC transformer' applications. The advantages, drawbacks and the operating principle of this concept, implemented with a `closed chain' magnetic structure have been already presented. In this work, the minimum energy storage operation, is applied to two different magnetic structures. These magnetic structures are called `closed chain' and `pyramidal' the main advantage of the `pyramidal' coupling structure is to improve the size of the converter without increasing the operating frequency. Both magnetic structures are analyzed, compared and experimentally implemented.

Desarrollo de un sistema de optimización económica para instalaciones de régimen especial

. Este proyecto tiene por objeto el desarrollo y la implantación de un sistema de optimización económica de instalaciones de producción de Régimen Especial, en una compañía eléctrica que representa a este tipo de instalaciones para su participación en los distintos mercados de electricidad. Inicialmente, se analizarán las opciones de participación en los distintos mercados de cada tecnología, en función de la legislación a la que pudieran estar acogidas las instalaciones del Régimen Especial; según tamaño y tipología de instalaciones, características o combustibles utilizados. En segundo lugar, se estudiará la relación entre dichas instalaciones y los distintos organismos reguladores del mercado; la Comisión Nacional de la Energía, el Ministerio de Industria y Turismo, Red Eléctrica de España y el Operador del mercado eléctrico. Posteriormente, se realizará un modelo de análisis estático de la situación actual de los mercados eléctricos, su estructura y funcionamiento, obteniendo para cada tipo de instalación el escenario de optimización de base, a partir del cual se podrá desarrollar el modelo dinámico que permitirá conocer en cualquier momento cuál será la mejor opción técnico-económica para cada tipo de instalación, optimizando así el presupuesto de las instalaciones objeto del estudio. Finalmente, este modelo se implementará en los sistemas de la compañía eléctrica, como una herramienta que permitirá asegurar la optimización en tiempo real a las instalaciones a las que representa en el mercado, optimizando sus propios costes a través de la implementación de este sistema automático y logrando así maximizar los ingresos de la compañía eléctrica. ABSTRACT DEVELOPMENT OF A SYSTEM OF ECONOMIC OPTIMIZATION FOR PLANTS OF SPECIAL REGIME. This project takes as an object the development and the implantation of a system of economic optimization of facilities of production of Special Regime, in an electrical company that it represents to this type of facilities for his participation in the different markets of electricity. Initially, there will be analyzed the options of participation in the different markets of every technology, depending on the legislation to which there could be received the facilities of the Special Regime; according to size and typology of facilities, characteristics or used fuels. Secondly, the relation will be studied between the above mentioned facilities and the different regulatory organisms of the market; the National Commission of the Energy, the Department of Industry and Tourism, Electrical Network of Spain and the Operator of the electrical market. Later, there will carry out a model of static analysis of the current situation of the electrical markets, his structure and functioning, obtaining for every type of installation the scene of base optimization, from which there will be able to develop the dynamic model who will allow to know at any time which will be the best technical - economic option for every type of installation, optimizing this way the budget of the facilities I object of the study. Finally, this model will be implemented in the systems of the electrical company, as a tool that will allow to assure the real time optimization to the facilities to which it represents on the market, optimizing his own costs across the implementation of this automatic system and managing this way to maximize the income of the electrical company.

Energy Analysis of Bare Electrodynamic Tethers

The design of an electrodynamic tether is a complex task that involves the control of dynamic instabilities, optimization of the generated power (or the descent time in deorbiting missions), and minimization of the tether mass. The electrodynamic forces on an electrodynamic tether are responsible for variations in the mechanical energy of the tethered system and can also drive the system to dynamic instability. Energy sources and sinks in this system include the following: 1) ionospheric impedance, 2) the potential drop at the cathodic contactor, 3) ohmic losses in the tether, 4) the corotational plasma electric field, and 5) generated power and/or 6) input power. The analysis of each of these energy components, or bricks, establishes parameters that are useful tools for tether design. In this study, the nondimensional parameters that govern the orbital energy variation, dynamic instability, and power generation were characterized, and their mutual interdependence was established. A space-debris mitigation mission was taken as an example of this approach for the assessment of tether performance. Numerical simulations using a dumbbell model for tether dynamics, the International Geomagnetic Reference Field for the geomagnetic field, and the International Reference Ionosphere for the ionosphere were performed to test the analytical approach. The results obtained herein stress the close relationships that exist among the velocity of descent, dynamic stability, and generated power. An optimal tether design requires a detailed tradeoff among these performances in a real-world scenario.

Leveraging heterogeneity for energy minimization in data centers

Energy consumption in data centers is nowadays a critical objective because of its dramatic environmental and economic impact. Over the last years, several approaches have been proposed to tackle the energy/cost optimization problem, but most of them have failed on providing an analytical model to target both the static and dynamic optimization domains for complex heterogeneous data centers. This paper proposes and solves an optimization problem for the energy-driven configuration of a heterogeneous data center. It also advances in the proposition of a new mechanism for task allocation and distribution of workload. The combination of both approaches outperforms previous published results in the field of energy minimization in heterogeneous data centers and scopes a promising area of research.

Design energy spectra for Turkey

This work proposes design energy spectra in terms of velocity, derived through linear dynamic analyses on Turkish registers and intended for regions with design peak acceleration 0.3 g or higher. In the long and mid period ranges the analyses are linear, taking profit of the rather insensitivity of the spectra to the structural parameters other than the fundamental period; in the short period range, the spectra are more sensitive to the structural parameters and nonlinear analyses would be required. The selected records are classified in eight groups according to the design input acceleration, the soil type, the earthquake magnitude and the near-source effects. For each of these groups, median and characteristic spectra are proposed (50% and 95% percentiles). These spectra have an initial linear growing branch in the short period range, a horizontal branch in the mid period range and a descending branch in the long period range.

Analyzing energy-efficient configurations in hexapod robots for demining applications

Purpose – Reducing energy consumption in walking robots is an issue of great importance in field applications such as humanitarian demining so as to increase mission time for a given power supply. The purpose of this paper is to address the problem of improving energy efficiency in statically stable walking machines by comparing two leg, insect and mammal, configurations on the hexapod robotic platform SILO6. Design/methodology/approach – Dynamic simulation of this hexapod is used to develop a set of rules that optimize energy expenditure in both configurations. Later, through a theoretical analysis of energy consumption and experimental measurements in the real platform SILO6, a configuration is chosen. Findings – It is widely accepted that the mammal configuration in statically stable walking machines is better for supporting high loads, while the insect configuration is considered to be better for improving mobility. However, taking into account the leg dynamics and not only the body weight, different results are obtained. In a mammal configuration, supporting body weight accounts for 5 per cent of power consumption while leg dynamics accounts for 31 per cent. Originality/value – As this paper demonstrates, the energy expended when the robot walks along a straight and horizontal line is the same for both insect and mammal configurations, while power consumption during crab walking in an insect configuration exceeds power consumption in the mammal configuration.

Control motion approach of a lower limb orthosis to reduce energy consumption

By analysing the dynamic principles of the human gait, an economic gait‐control analysis is performed, and passive elements are included to increase the energy efficiency in the motion control of active orthoses. Traditional orthoses use position patterns from the clinical gait analyses (CGAs) of healthy people, which are then de‐normalized and adjusted to each user. These orthoses maintain a very rigid gait, and their energy cosT is very high, reducing the autonomy of the user. First, to take advantage of the inherent dynamics of the legs, a state machine pattern with different gains in eachstate is applied to reduce the actuator energy consumption. Next, different passive elements, such as springs and brakes in the joints, are analysed to further reduce energy consumption. After an off‐line parameter optimization and a heuristic improvement with genetic algorithms, a reduction in energy consumption of 16.8% is obtained by applying a state machine control pattern, and a reduction of 18.9% is obtained by using passive elements. Finally, by combining both strategies, a more natural gait is obtained, and energy consumption is reduced by 24.6%compared with a pure CGA pattern.

Design energy input spectra for high seismicity regions based on Turkish registers

This work proposes design energy spectra in terms of an equivalent velocity, intended for regions with design peak acceleration 0.3 g or higher. These spectra were derived through linear and nonlinear dynamic analyses on a number of selected Turkish strong ground motion records. In the long and mid period ranges the analyses are linear, given the relative insensitivity of the spectra to structural parameters other than the fundamental period; conversely, in the short period range, the spectra are more sensitive to the structural parameters and, hence, nonlinear analyses are required. The selected records are classified in eight groups with respect to soil type (stiff or soft soil), the severity of the earthquake in terms of surface magnitude Ms(Ms≤ 5.5 and Ms> 5.5) and the relevance of the near-source effects (impulsive or vibratory). For each of these groups, median and characteristic spectra are proposed; such levels would respectively correspond to 50 and 95 % percentiles. These spectra have an initial linear growing branch in the short period range, a horizontal branch in the mid period range and a descending branch in the long period range. Empirical criteria for estimating the hysteretic energy from the input energy are suggested. The proposed design spectra are compared with those obtained from other studies.

SMArc: a proposal for a smart, semantic middleware architecture focused on Smart City energy management

Among the main features that are intended to become part of what can be expected from the Smart City, one of them should be an improved energy management system, in order to benefit from a healthier relation with the environment, minimize energy expenses, and offer dynamic market opportunities. A Smart Grid seems like a very suitable infrastructure for this objective, as it guarantees a two-way information flow that will provide the means for energy management enhancement. However, to obtain all the required information, another entity must care about all the devices required to gather the data. What is more, this entity must consider the lifespan of the devices within the Smart Grid—when they are turned on and off or when new appliances are added—along with the services that devices are able to provide. This paper puts forward SMArc—an acronym for semantic middleware architecture—as a middleware proposal for the Smart Grid, so as to process the collected data and use it to insulate applications from the complexity of the metering facilities and guarantee that any change that may happen at these lower levels will be updated for future actions in the system.

3-Phase Rectifier System with very demanding dynamic load: Architecture analysis and control strategy

A distributed power architecture for aerospace application with very restrictive specifications is analyzed. Parameters as volume, weight and losses are analyzed for the considered power architectures. In order to protect the 3 phase generator against high load steps, an intermediate bus (based in a high capacitance) to provide energy to the loads during the high load steps is included. Prototypes of the selected architecture for the rectifier and EMI filter are built and the energy control is validated.

Leakage and temperature aware server control for improving energy efficiency in data centers

Reducing the energy consumption for computation and cooling in servers is a major challenge considering the data center energy costs today. To ensure energy-efficient operation of servers in data centers, the relationship among computa- tional power, temperature, leakage, and cooling power needs to be analyzed. By means of an innovative setup that enables monitoring and controlling the computing and cooling power consumption separately on a commercial enterprise server, this paper studies temperature-leakage-energy tradeoffs, obtaining an empirical model for the leakage component. Using this model, we design a controller that continuously seeks and settles at the optimal fan speed to minimize the energy consumption for a given workload. We run a customized dynamic load-synthesis tool to stress the system. Our proposed cooling controller achieves up to 9% energy savings and 30W reduction in peak power in comparison to the default cooling control scheme.

Multiphase Current Controlled Buck Converter with energy recycling Output Impedance Correction Circuit (OICC)

This work is related to the output impedance improvement of a Multiphase Buck converter with Peak Current Mode Control (PCMC) by means of introducing an additional power path that virtually increases the output capacitance during transients. Various solutions that can be employed to improve the dynamic behavior of the converter system exist, but nearly all solutions are developed for a Single Phase Buck converter with Voltage Mode Control (VMC), while in the VRM applications, due to the high currents, the system is usually implemented as a Multiphase Buck Converter with Current Mode Control. The Output Impedance Correction Circuit (OICC) is used to inject or extract a current n-1 times larger than the output capacitor current, thus virtually increasing n times the value of the output capacitance during the transients. Furthermore, this work extends the OICC concept to a Multiphase Buck Converter system while comparing proposed solution with the system that has n times bigger output capacitor. In addition, the OICC is implemented as a Synchronous Buck Converter with PCMC, thus reducing its influence on the system efficiency

A novel topology control approach to maintain the node degree in dynamic wireless sensor networks

Topology control is an important technique to improve the connectivity and the reliability of Wireless Sensor Networks (WSNs) by means of adjusting the communication range of wireless sensor nodes. In this paper, a novel Fuzzy-logic Topology Control (FTC) is proposed to achieve any desired average node degree by adaptively changing communication range, thus improving the network connectivity, which is the main target of FTC. FTC is a fully localized control algorithm, and does not rely on location information of neighbors. Instead of designing membership functions and if-then rules for fuzzy-logic controller, FTC is constructed from the training data set to facilitate the design process. FTC is proved to be accurate, stable and has short settling time. In order to compare it with other representative localized algorithms (NONE, FLSS, k-Neighbor and LTRT), FTC is evaluated through extensive simulations. The simulation results show that: firstly, similar to k-Neighbor algorithm, FTC is the best to achieve the desired average node degree as node density varies; secondly, FTC is comparable to FLSS and k-Neighbor in terms of energy-efficiency, but is better than LTRT and NONE; thirdly, FTC has the lowest average maximum communication range than other algorithms, which indicates that the most energy-consuming node in the network consumes the lowest power.

A dynamic factor model for mid-term forecasting of wind power generation

The main objective of this paper is the development and application of multivariate time series models for forecasting aggregated wind power production in a country or region. Nowadays, in Spain, Denmark or Germany there is an increasing penetration of this kind of renewable energy, somehow to reduce energy dependence on the exterior, but always linked with the increaseand uncertainty affecting the prices of fossil fuels. The disposal of accurate predictions of wind power generation is a crucial task both for the System Operator as well as for all the agents of the Market. However, the vast majority of works rarely onsider forecasting horizons longer than 48 hours, although they are of interest for the system planning and operation. In this paper we use Dynamic Factor Analysis, adapting and modifying it conveniently, to reach our aim: the computation of accurate forecasts for the aggregated wind power production in a country for a forecasting horizon as long as possible, particularly up to 60 days (2 months). We illustrate this methodology and the results obtained for real data in the leading country in wind power production: Denmark