Power Levels In Order Research Articles

Design and implementation of energy reshaping based fuzzy logic control for optimal power extraction of PMSG wind energy converter

Given the greater penetration of wind power, the impact of wind generators on grid electricity reliability imposes additional requirements. One of the most common technologies in wind power generating schemes is the permanent magnet synchronous generator (PMSG) converter. However, the controller calculation is difficult due to the nonlinear dynamical and time-varying characteristics of this type of conversion system. This study develops a unique intelligent controller approach based on the passivity notion that tracks velocity and maintains it functioning at the optimum torque. To address the robustness issues encountered by traditional generator-side converter (MSC) strategies such as proportional-integral (PI), this suggested scheme integrates a passivity-based procedure with a fuzzy logic control (FLC) methodology for a PMSG-based wind power converter. The suggested controller is distinguished by the fact that the nonlinear features are compensated in a damped manner rather than canceled. To achieve the required dynamic, the fuzzy controller is used, which ensures quick convergence and global stability of the closed loop system. The development of the maximum power collected, the lowered fixed gains, and the real-time application of the control method are the primary contributions and novelties. The primary objectives of this project are to manage DC voltage and attain adequate reactive power levels in order to provide dependable and efficient electricity to the grid. The proposed scheme is being used to regulate the MSC, while the grid-side employs a traditional proportional-integral method. The efficiency of the suggested technique is investigated numerically using MATLAB/Simulink software. Furthermore, the processor-in-the-loop (PIL) tests are carried out to demonstrate that the suggested regulator is practically implementable.

Physics basis for the ICRF system of the SPARC tokamak

Ion cyclotron range of frequencies (ICRF) heating will be the sole auxiliary heating method on SPARC for both full-field (Bt0 ~ 12 T) D–T operation and reduced field (Bt0 ~ 8 T) D–D operation. Using the fast wave at ~120 MHz, good wave penetration and strong single-pass absorption is expected for D–T(3He), D(3He), D(H) and4He(H) heating scenarios. The dependences of wave absorption on${k_\parallel }$,3He concentration, resonance location, antenna poloidal location and losses on alpha particles and ash have been studied. The antenna loading has been assessed by comparison with the Alcator C-Mod antennae. An antenna spectrum of${k_\parallel }\sim 15\text{--}18\,{\textrm{m}^{ - 1}}$is shown to be good for both core absorption and edge coupling. For the control of impurity sources, the antenna straps are rotated ~10° to be perpendicular to the B field and the straps can run with different power levels in order to optimize the antenna spectrum and to minimize the image current on the antenna frame. Combining the physics constraints with the SPARC port design, maintenance requirement and contingency against antenna failure during D–T operation, we plan to mount on the inner wall of the vacuum vessel a total of 12 4-strap antennae in 6 ports while keeping 3-strap antennae that are insertable and removable on port plugs as the backup option.

Dynamic modulation scaling enabled multi-hop topology control for time critical wireless sensor networks

The previous work on connection driven topology control has shown that it has significant potential to reduce energy consumption of Wireless Sensor Networks (WSNs). Dynamic Modulation Scaling (DMS) which is a technique that manages transmission power levels in order to change the number of bits encoded per symbol has a direct impact on connection driven topology control. In this paper we investigate the transmission scheduling of multi-hop real-time WSNs equipped with DMS enabled radio chips while taking the effect of DMS on topology control into account. To our best knowledge, this is the first paper that addresses this issue. The current work on DMS enabled WSN tend to rely on theoretical DMS models to predict network performance metrics. However, there is little, if any, work that is based upon empirically verified network performance outcomes using DMS especially on its effect on connection driven topology control. This paper fills this gap by using GNU Radio and Software Defined Radio hardware to show how to emulate DMS in low power wireless systems and measure the impact of varying Signal-to-Noise levels, distance and elevation on throughput and delivery rates for different DMS control strategies. Next, we present the Mixed Integer Nonlinear Optimization Problem of minimizing energy consumption of DMS enabled connection driven topology control on real-time WSNs. Lastly, we present two polynomial time heuristics and compare their performance against the optimal solution.

Drying rate control in microwave assisted processing of sliced apples

The most enhanced microwave systems for the preparation of quality-dehydrated fruits continuously adjust the power level in order to maintain the product temperature above a target value. As a result, typical drying curves that exhibit high drying rates in the middle stage are obtained. This can often lead to quality damage or undesirable changes on food colour and texture. In response to these issues, a microwave system is proposed that can realise drying processes keeping drying rates constant. This approach required a continuous temperature adjustment of the apple slices under test, whose temperature was detected by a computer-aided infrared thermography system. Since temperature corrections were required only during the middle stage of the process, the overall drying time was only slightly affected by the proposed control strategy. Nevertheless, compared to microwave drying with different constant temperatures (60, 70 and 80 °C), the resultant benefits of operating at constant drying rates included an improvement of texture and rehydration properties. No differences in colour of sliced apples were observed.

A methodology for LED placement in luminaires without lenses for optimal illumination of complex target areas

Street lighting still faces some challenges, e.g., reducing power consumption, lowering light pollution, and making adaptive luminaires more effective among many other concerns. It is evident that the arrival of light-emitting diodes (LEDs) in lighting systems has altered the state-of-the-art and design strategies in lighting. In a traditional approach, a single lamp, i.e., a single light point, is used. Then, by means of lenses, the specification of the radiation pattern is met. However, LED lamps allow for higher flexibility. It is possible to configure many small light sources, positioned and oriented at will. In this paper, a novel software tool able to provide the most suitable solution starting from a certain target lighting specification is proposed. This tool specifies the smallest number of LED required, their geometric orientation, and power levels in order to comply with all the specifications. It is especially useful when trying to light up an irregular, twisted area, although this methodology can be adapted to any geometry. Furthermore, to validate the proposed methodology, two lamps were tested in the streets of Oviedo, Spain, using a staggered arrangement.

Optimization of a Power Splitting Protocol for Two-Way Multiple Energy Harvesting Relay System

Energy harvesting (EH) combined with cooperative communications constitutes a promising solution for future wireless technologies. It enables additional efficiency and increased lifetime to wireless networks. This paper investigates a multiple-relay selection scheme for an EH-based two-way relaying (TWR) system. All relays are considered EH nodes that harvest energy from renewable energy and radio frequency (RF) sources. Some of them are selected to forward data to the destinations. The power splitting (PS) protocol, by which the EH node splits the input RF signal into two components for EH and information transmission, is adopted at the relay nodes. The objective is to jointly optimize: 1) the set of selected relays; 2) their PS ratios; and 3) their transmit power levels in order to maximize data rate-based utilities over multiple coherent time slots. A joint-optimization solution based on geometric programming (GP) and binary particle swarm optimization is proposed to solve non-convex problems for two utility functions reflecting the level of fairness in the TWR transmission. Numerical results illustrate the system’s behavior versus various parameters and show that the performance of the proposed scheme is very close to that of the optimal branch-and-bound method and that GP outperforms the dual problem-based method.

Extending Wireless Rechargeable Sensor Network Life without Full Knowledge.

When extending the life of Wireless Rechargeable Sensor Networks (WRSN), one challenge is charging networks as they grow larger. Overcoming this limitation will render a WRSN more practical and highly adaptable to growth in the real world. Most charging algorithms require a priori full knowledge of sensor nodes’ power levels in order to determine the nodes that require charging. In this work, we present a probabilistic algorithm that extends the life of scalable WRSN without a priori power knowledge and without full network exploration. We develop a probability bound on the power level of the sensor nodes and utilize this bound to make decisions while exploring a WRSN. We verify the algorithm by simulating a wireless power transfer unmanned aerial vehicle, and charging a WRSN to extend its life. Our results show that, without knowledge, our proposed algorithm extends the life of a WRSN on average 90% of what an optimal full knowledge algorithm can achieve. This means that the charging robot does not need to explore the whole network, which enables the scaling of WRSN. We analyze the impact of network parameters on our algorithm and show that it is insensitive to a large range of parameter values.

Modular Photovoltaic Charging Station for UAE University Golf Carts

Abstract In this paper, a modular charging design that uses the sunlight as input power to charge the golf carts used in the United Arab Emirates University (UAEU) campus is presented. The design of the charging station involves several steps such determining the required power level in order to meet the load requirement, optimizing the charger design, and most importantly, evaluating the economic feasibility of the charging station. An overview of the project is presented followed by design considerations and evaluation of the system size and economic feasibility.

Infrared Sensor-Based Temperature Control for Domestic Induction Cooktops

In this paper, a precise real-time temperature control system based on infrared (IR) thermometry for domestic induction cooking is presented. The temperature in the vessel constitutes the control variable of the closed-loop power control system implemented in a commercial induction cooker. A proportional-integral controller is applied to establish the output power level in order to reach the target temperature. An optical system and a signal conditioning circuit have been implemented. For the signal processing a microprocessor with 12-bit ADC and a sampling rate of 1 Ksps has been used. The analysis of the contributions to the infrared radiation permits the definition of a procedure to estimate the temperature of the vessel with a maximum temperature error of 5 °C in the range between 60 and 250 °C for a known cookware emissivity. A simple and necessary calibration procedure with a black-body sample is presented.

Ray entity based postprocessing of ray‐tracing data for continuous modeling of radio channel

AbstractRay‐tracing data are usually given as angles of arrival and departure, transmitter and receiver coordinates, ray length and delay, received power level, and polarity. Usually, these values are given in raw data with some resolution that covers the area of interest where the simulation is performed. There are two main drawbacks of such approach: first, a huge amount of storage capacity is typically needed and second, although the area of interest is covered by a certain resolution, it is nearly impossible to interpolate between sample points and new time, and memory consuming simulations are necessary in order to increase the resolution of the simulations. This paper addresses the two mentioned drawbacks of ray tracing, suggesting a procedure based on the concept of ray entities both to enable continuous interpolation of ray‐tracing data and reduce the memory needed for storing data. Ray entity is a set of rays that all undergo the same series of propagation phenomena (direct ray, diffraction, reflection, or scattering) on the same objects (building walls or edges). The method is given and illustrated for reflection and diffraction phenomena, and diffuse scattering was not included, but discussion is easily extended to this propagation type as well. The paper gives detailed statistics of entities' length and rays' count per simulated receiver point in few illustrative examples and provides an insight on how to interpolate angles of arrival and departure, ray length, and received power level in order to provide a continuous description of the radio environment.

Lifetime reduction due to photodarkening phenomenon in ytterbium-doped fibers and rate equation term

In this Letter, the lifetime temporal reduction in ytterbium-doped aluminosilicate fibers due to pump-induced photodarkening (PD) has been reported. A linear correlation between lifetime reduction at equilibrium state and equilibrium losses due to the PD phenomenon was demonstrated. A squared-law dependence between lifetime reduction and dopant concentration (percent by weight) suggests a possible correction term for the rate equations system which allows improving its accuracy. Finally, a quenching effect was also observed for different pump power levels in order to find the corresponding lifetime value for different inversion levels. The quantitative analysis allows determination of the PD quenching term in the laser rate equations system to properly model a laser device that may be affected by this process.

Enriching self‐organizing networks use cases with opportunistic features: a coverage and capacity optimization paradigm

SUMMARYSelf‐organizing networks (SONs) have been introduced into long‐term evolution in order to configure and optimize the network in an autonomic manner. However, in some situations the reconfiguration of the entire network is not the most cost‐efficient solution. Consequently, opportunistic networks have been introduced as operator‐governed, coordinated extensions of the infrastructure that are created dynamically where and when they are needed, exploiting the radio environment. This work proposes an enhanced SON functional architecture (FA) with opportunistic features in order to handle such situations through the manipulation of ONs. In addition, the proposed FA is utilized in a coverage and capacity optimization use case, where small cells are deployed in order to extend the capacity of a macro base station (BS). Users opportunistically exploit the resources (i.e. resource blocks) of the small cells. In addition, the small cells are configured to the optimal power level in order to maximize the users’ throughput without causing interference to the other users. Two different approaches of controlling the interference among the macro BS and the small cells are presented, namely soft constraint and hard constraint cases. Furthermore, apart from maximizing the users’ throughput, emphasis is given to the fairness among the users and on the quality‐of‐service provision through a proper resource allocation. The evaluation proved that when small cells are introduced the system's throughput is increased by 12.76% when the macro BS and the small cells cannot use the same resource blocks simultaneously (hard constraint case) and by 8.25% when the reuse is possible. Copyright © 2013 John Wiley & Sons, Ltd.

Multiple narrowband interference suppression for UWB communication systems in Nakagami fading channels

This paper investigates the performance of ultra-wideband (UWB) communication systems in the presence of multiple in-band narrowband interference signals in a Nakagami-m frequency selective fading channel. The UWB systems have a restraint on their transmission power levels in order to control its interference to other in-band operating services; however UWB systems unavoidably suffer from the interference caused by the coexisting systems such as the IEEE802.11a signal, making it extremely difficult to maintain adequate signal-to-noise-and interference ratio (SNIR) levels. In order to mitigate the impact of such strong interference the paper proposes a suppression technique which introduces spectral nulls at the operating frequencies of the narrowband interference (NBI) signals. The bit error rate performance of the proposed scheme is derived in a Nakagami multi-path frequency selective fading channel and validated with simulation. The results show that with the use of such proposed technique the NBI impact can be effectively suppressed leading to an improvement to the bit error rate performance of the UWB communication systems. A comparison with a notch filter-based case is also presented where it will be shown that the proposed technique out performs a perfectly tuned notch filter.

DEVELOPMENT OF REACTOR POWER CONTROL LOGIC FOR THE POWER MANEUVERING OF KALIMER-600

We developed an achievable control logic for the reactor power level during a power maneuvering event and set up some constraints for the control of the reactor power in a conceptual sodium-cooled fast reactor (KALIMER-600) that was developed at KAERI. For simulating the dynamic behaviors of the plant, we developed a fast-running performance analysis code. Through various simulations of the power maneuvering event, we evaluated some suggested control logic for the reactor power and found an achievable control logic. The objective of the control logic is to search for the position of the control rods that would keep the average temperature of the primary pool constant and, concurrently, minimize the power deviation between the reactor and the BOP cycle during the power maneuvering. In addition, the flow rates of the primary pool and the intermediate loop should be changed according to the power level in order to not violate the constraints set up in this study. Also, we evaluated some movement speeds of the control rods and found that a fast movement of the control rods might cause the power to fluctuate during the power maneuvering event. We suggested a reasonable movement speed of the control rods for the developed control logic.

A Generalized Memory Polynomial Model for Digital Predistortion of RF Power Amplifiers

Conventional radio-frequency (RF) power amplifiers operating with wideband signals, such as wideband code-division multiple access (WCDMA) in the Universal Mobile Telecommunications System (UMTS) must be backed off considerably from their peak power level in order to control out-of-band spurious emissions, also known as “spectral regrowth.” Adapting these amplifiers to wideband operation therefore entails larger size and higher cost than would otherwise be required for the same power output. An alternative solution, which is gaining widespread popularity, is to employ digital baseband predistortion ahead of the amplifier to compensate for the nonlinearity effects, hence allowing it to run closer to its maximum output power while maintaining low spectral regrowth. Recent improvements to the technique have included memory effects in the predistortion model, which are essential as the bandwidth increases. In this paper, we relate the general Volterra representation to the classical Wiener, Hammerstein, Wiener–Hammerstein, and parallel Wiener structures, and go on to describe some state-of-the-art predistortion models based on memory polynomials. We then propose a new generalized memory polynomial that achieves the best performance to date, as demonstrated herein with experimental results obtained from a testbed using an actual 30-W, 2-GHz power amplifier.

Equilibria in Topology Control Games for Ad Hoc Networks

We study topology control problems in ad hoc networks where network nodes get to choose their power levels in order to ensure desired connectivity properties. Unlike most other work on this topic, we assume that the network nodes are owned by different entities, whose only goal is to maximize their own utility that they get out of the network without considering the overall performance of the network. Game theory is the appropriate tool to study such selfish nodes: we define several topology control games in which the nodes need to choose power levels in order to connect to other nodes in the network to reach their communication partners while at the same time minimizing their costs. We study Nash equilibria and show that-among the games we define-these can only be guaranteed to exist if each network node is required to be connected to all other nodes (we call this the STRONG CONNECTIVITY GAME). For a variation called CONNECTIVITY GAME, where each node is only required to be connected (possibly via intermediate nodes) to a given set of nodes, we show that Nash equilibria do not necessarily exist. We further study how to find Nash equilibria with incentive-compatible algorithms and compare the cost of Nash equilibria to the cost of a social optimum, which is a radius assignment that minimizes the total cost in a network where nodes cooperate. We also study variations of the games; one where nodes not only have to be connected, but k-connected, and one that we call the REACHABILITY GAME, where nodes have to reach as many other nodes as possible, while keeping costs low. We extend our study of the STRONG CONNECTIVITY GAME and the CONNECTIVITY GAME to wireless networks with directional antennas and wireline networks, where nodes need to choose neighbors to which they will pay a link. Our work is a first step towards game-theoretic analyses of topology control in wireless and wireline networks.

MATS: multichannel time-spread scheduling in mobile ad hoc networks

Wireless mobile ad hoc networks (MANETs) have received considerable attention in the last few years. Most research works focus on single-channel MANETs with a single power-level in order to simplify the network design and analysis. How to take advantage of multiple channels and multiple power levels in MANETs poses a serious challenging problem. Recently, a few multichannel transmission protocols such as collision-avoidance transmission scheduling (CATS) have been proposed to harvest the advantage of high transmission efficiency when multiple channels are deployed. Although such protocols do provide ways to coordinate the use of multiple channels, there exist some serious problems such as the throughput fast drop-off under heavy traffic loads. In this paper, we propose a new protocol, namely, multichannel time-spread scheduling (MATS), which attempts to tackle these problems. In MATS, nodes with transmission requests are divided into three groups, which carry out channel reservations in parallel and can simultaneously support unicasting, multicasting and broadcasting at the link level. MATS ensures successful and collision-free data transmissions using the reserved channels and allows multicasting and broadcasting high priorities over unicasting. Both theoretical analysis and extensive simulation studies are carried out which show that the performance of MATS under high traffic loads significantly outperforms the existing schemes.

Electron Linear Accelerator Based on the Crossed-Wave Electric and Static Magnetic Field

A new type of linear electron accelerator, based on the crossed-wave-electric field and static magnetic field system known as the vp×B acceleration mechanism observed originally in plasma, has been demonstrated in vacuum for the first time. In this scheme a static magnetic field is applied vertically to direction of the wave propagation and the particles are accelerated along the wavefront in a constant phase with respect to the wave. The present machine can be either a conventional linear accelerator or a new type of vp×B accelerator without any modification. An energy gain of 12.8 keV for electrons is observed from an incident energy of 66 keV in a 0.5 m accelerator, when an external magnetic field of 2.5 G is applied. The energy gain is 30% higher than that of conventional linacs. The energy gain is proportional to the square of the applied magnetic field strength B0$as long as the electrons are trapped within a wave trough. Experiments have been carried out with two different RF power levels in order to confirm the trapping condition for electrons, which depends on both the electric field and the applied magnetic field. The results of experiments and theories are in fairly good agreement.

Separated-local-field measurements using low-power multipulse decoupling

The separated-local-field experiment in the NMR of solids is used to measure the strength of the static dipolar interaction between isolated heteronuclear spin pairs (Z3). In the case of static solids, the strength of the dipolar interaction can be used to calculate the heteronuclear interatomic distance (4). Alternatively, in the presence of some molecular motion and a known interatomic distance, the reduction of the strength of the heteronuclear dipolar interaction due to that motion can be used to obtain information about the amplitudes of those molecular motions (3). Techniques to obtain this local-field information are two-dimensional experiments which contain the usual preparation, evolution, and detection periods. During the Preparation period, the spin system comes to equilibrium; then observe spin magnetization is generated (usually by means of Hartmann-Hahn cross polarization). In the second period, the magnetization is allowed to evolve for a time t, while the coupled heteronuclei are subjected to a homonuclear decoupling, allowing heteronuclear interactions to survive. In the final period, t2, the observe nuclei are detected under full heteronuclear decoupling. For this two-dimensional experiment, the t, increment is a cycle of some appropriate homonuclear decoupling scheme, usually WAHUHA (5) or MREV-8 (68). These “windowed” sequences, however, require very high power levels in order to obtain reasonable results. Typically, RF fields greater than 2 mT, cortespomimg to a 90” pulse length of less than three microseconds, are required to homodecouple protons. This demanding requirement is generally not available to the routine or casual solids NMR spectroscopist. This report describes a version of the separated-locall the usual WAHUHA homondear decoupling pulse train has been replaced by the more efficient windowless BLEW12 (9) sequence. Also, the time interval between cross polarization and the refocusing pulse was not constrained to be an integer number of multipulse cycles. For this work, a half-cycle of BLEW-12 is used as the tl increment time. The half-cycle represents the minimum pulse sequence necessary to cause zero-order dipolar interactions to vanish (9).

Signaling of Remotely Controlled Railway Trains

A train control system has been evaluated in which a remote digital computer is used as the feedback element of a servomechanism. Telemetry signals are required between the train and computer and in the reverse direction, and engineering constraints are placed on the implementation. Signaling requirements are described, and experimental measurements of the electrical noise and ensuing analyses are presented. Equipment using phase and frequency modulation was built and tested, and a serial coding system was tested at typical railway properties. Measurements were made at diminishing power levels in order to determine margins of communication security; error rates approaching 1 in 105are anticipated for an operating train control system.