Flexible Output Research Articles

Efficient generation of self-avoiding, semiflexible rotational isomeric chain ensembles in bulk, in confined geometries, and on surfaces

We provide an efficient ready-to-run code gensaw that generates single or large ensembles of self-avoiding, flexible, semiflexible, rotationally isometric or helical chains in the bulk or subject to arbitrary confinement and tethering conditions, where we allow for arbitrary intramolecular bending and dihedral energy functions. The resulting configuration files are provided in various common formats and can be immediately used to do molecular simulations or statistical analysis. We work out analytic expressions for the mean squared end-to-end distance and gyration radius of the semiflexible, helical and rotational isomeric state models with a finite number of bonds and arbitrary interaction potentials for direct comparison and testing of the code in the limiting case of unconfined phantom chains. In addition to the graphics-free linux standalone batch version gensaw that creates configuration and other files for high throughput applications from the command line, we provide an interactive online version gensaw-visualization that serves as platform-independent graphical user interface, and animates the resulting conformations using a remote gensaw server. Program summaryProgram title:gensawCPC Library link to program files:https://doi.org/10.17632/8xfgf88f3w.1Licensing provisions: MITProgramming languages: fortran 90, perl (standalone batch version) or java (interactive online version)Required software:ifort 16+ or gfortran 4+, perl 5+ (standalone batch version), jre 1.8.0+ (interactive online version)Nature of problem: Efficient creation of self-avoiding, semiflexible multibead walks/chains of variable contour length, subject to arbitrary confinement and tethering conditions, characterized by a conformational energy that is composed of arbitrary bending and torsion contributions. The code must produce an ensemble of such chains, using a flexible output format. For the limiting case of chains with zero thickness, the code should reproduce analytic results for the ideal chains.Solution method: We use an adapted enrichment procedure that optimizes its parameters on the fly and derive all analytic results for semiflexible chains with arbitrary bending and torsion potentials for comparison with the created ensembles. While gensaw creates configuration and optionally other files from the command line, gensaw-visualization serves as a platform-independent graphical user interface and allows to visualize and animate the conformations.

Three-Stage Load Modulated Power Amplifier With Efficiency Enhancement at Power Back-Off

This article presents the analysis and design of a three-stage load modulated power amplifier (PA), in which three amplifiers, each with different biasing, are connected to a four-port coupler. It is illustrated that, by properly configuring current relationships between the three amplifiers, this new load modulated PA can provide flexible output power back-off (OBO) and achieve high efficiency within a large OBO range. A detailed theoretical analysis and design methodology are given. In this architecture, the OBO level can be adjusted by simply setting bias conditions of the relevant amplifiers that correspond to the current relationships. Therefore, after circuit fabrication, the OBO range can still be reconfigured without redesigning the circuit. To validate the proposed approach, a prototype operating at 3.45 GHz is demonstrated and implemented with gallium nitride (GaN) transistors. The measured saturated output power reaches 45 dBm with 70.1% drain efficiency. At 6-/8-/10-dB OBO, the fabricated PA can provide up to 62.1%/53.8%/47.3% drain efficiency, respectively. When driven by a 60-MHz 9-dB peak-to-average power ratio (PAPR) long-term evolution (LTE) signal, the PA provides 34-dBm average output power with 44.3% average efficiency. Moreover, measurement results prove that the PA can offer efficiency enhancement when the OBO is reconfigured to 8 or 12 dB after fabrication.

WITHDRAWN: Neural network based hybrid power scheme with constant output using three DC source

Abstract Nowrecent day’s Solar Power is essential for all domestic purposes due to the demand of power consumption. But the single Solar system doesn’t provide the constant output because of solar irradiation. To overcome this problem, by using proposed hybrid power scheme. The projected system has alone four power semiconductor control that are separately dominated by different duty cycle ratio values. Using the duty cycles ratio to attain the maximum power of voltage source, Fuel Cell power and storage power are deliver to flexible output voltage through the load. Using on the storage power, three various power operation modes and controlled outputs are obtained by using neural network controller simulation in MATLAB. This controller produces the constant output voltage for hybrid power system. To develop the Neural Network control for controlling the parameters of regulate the converter to increase boostedvalue voltage and fast output response. The parameters required for the development of neural network control is obtained from the boost converter under various operating conditions. To train the neural network using the samples collected from the boost converter and a portion of the samples are utilized to test the performance of proposed controller.

Output control of wireless power transmission system based on dynamic parameter tuning

Flexible output power control is very important for wireless power transmission system. In the wireless charging application of electric vehicles, the load is usually the battery. For the battery, both constant current charging and constant voltage charging are needed. In the constant voltage stage, the current should continue to decrease, so we need to adjust the output current of the system in the later stage of charging. Nowadays, the main methods used in WPT system are phase shift and pulse width modulation, adding a first stage DC-DC circuit before the inverter, and controlling the energy injection of the transmitting coil. In view of its shortcomings, this paper uses a method based on adjusting capacitor parameters to achieve output control. Firstly, the influence of capacitance parameters on output current is analyzed, and the relationship between capacitance parameters and output current is deduced; secondly, its advantages are analyzed, and the working principle is analyzed through simulation; finally, the feasibility and correctness of the control method are verified by experiment and simulation.

Multi-input, Multi-output Hybrid Energy Systems

Summary Jurisdictions and industries are setting ambitious goals to decarbonize energy systems. Low-cost wind, solar, and natural gas and the resultant dynamic electric grid require energy technologies to adapt in order to meet key attributes for modern energy systems: resilience, reliability, security, affordability, flexibility, and sustainability. When considering energy sources independently and competitively, value-added synergies among energy technologies may be overlooked for meeting demanding, multidimensional requirements. This paper presents novel concepts for tightly coupled hybrid energy systems that leverage capabilities of diverse energy generators, including renewable, nuclear, and fossil with carbon capture, to provide power, heat, mobility, and other energy services. The paper also presents a framework for engineering-based modeling and analysis for complex optimization of energy generation, transmission, services, processes and products, and market interactions. New modeling capabilities are needed to adequately represent multi-input, multi-output tightly coupled hybrid energy systems that utilize multiple feedstocks to create multiple products and services in novel and synergistic ways through increased coordination of energy systems and tightly coupled hybrid system configurations.

Presynchronous Grid-Connection Strategy of Virtual Synchronous Generator Based on Virtual Impedance

The virtual synchronous generator (VSG) technology of inverter is widely used to provide the inertia and damping support for power system. However, an additional measurement device PLL (phase-locked loop) is required in the virtual synchronous generator grid connection to track the voltage phase, amplitude, and frequency, which restricts the flexible output of the distributed power generation system. To tackle this challenge, a method for grid-connected control of virtual synchronous generator based on virtual impedance is proposed. It is assumed that there is a virtual power exchange between the synchronous machine and the power grid when the virtual synchronous generator is off-grid, the virtual impedance is developed to calculate the virtual current, and when the virtual current is zero, the output voltage of the VSG can be synchronized with the voltage of the power grid, thereby seamlessly switching between off-grid and grid-connected VSG. A semiphysical simulation platform is built based on RT-LAB; simulation and experimental results show that the proposed grid synchronization control strategy of the VSG can achieve seamless transform between different VSG modes, which is simpler than the conventional synchronization control, while having a good active and reactive power tracing performance.

A Repetitive High-Current Pulse Generator Circuit Based on Multistage Pulse Transformers

The application of inductive energy storage in the generation of high-current pulses has attracted considerable attention during recent years. In this article, a new inductive high-current pulse generator circuit is proposed based on XRAM (MARX spelled backword) current multiplier converter concept and multistage pulse transformers by using power electronic switches. This circuit is capable to recover the residual energy and generate repetitive high-current pulses with a flexible output pattern. To verify the circuit operation, simulation and experimental results of a two-stage laboratory prototype are presented. The results confirm the theoretical analysis and show the validity of the converter scheme.

Single DC Source Multilevel Inverter with Changeable Gains and Levels for Low-Power Loads

Different types of multilevel converters have been used to convert DC voltage to AC voltage for different applications. It is, however, desirable for flexible AC output voltage to be created from a single DC source at lower cost. This paper presents a new type of single DC source multilevel inverter which has the ability to create a different number of levels with low rate components. This device is also able boost the magnitude of the output voltage by means of a variable gain with one DC source. The advantages of the multilevel inverter are rapid stepping among levels, and its ability to produce different ranges of levels (seven, nine and eleven) and gains (two, four and eight). The proposed multilevel inverter includes six semiconductor switches, eight diodes, two capacitors and two inductors, making it suitable for low-power applications. A simulation in MATLAB and experimental tests on a prototype setup showed good performance for different modulations, with THD% down to 2.29%, which are meets the IEEE standard (IEEE 519).

Economic & environmental effects of priority dispatch of renewable energy considering fluctuating power output of coal-fired units

It is generally believed that priority dispatch of renewable energy results in decreases in the economic cost and emission reduction of a power system. However, when peak shaving cost of coal-fired units is considered, views are different. In this study, we focus on the additional cost resulting from fluctuating output of coal-fired units during the peak shaving process for renewable energy priority dispatch. Data from the Beijing-Tianjin-Tangshan Power Grid (BTT) in China were used. It was found that the priority dispatch of renewable energy resulted in an increase in environmental quality, which was primarily attributed to the reduction in CO2 emissions, and a decrease in the total economic cost, even when the negative impact of the fluctuating output of coal-fired units on energy efficiency was considered. An analysis of the impact of more flexible output of coal-fired units indicated that at the current technical level, greater peak shaving did not always have a positive impact on economic cost. Policy implications are provided in the end.

Sub-nanosecond-speed frequency-reconfigurable photonic radio frequency switch using a silicon modulator

Radio frequency (RF) switches are essential for implementing routing of RF signals. However, the increasing demand for RF signal frequency and bandwidth is posing a challenge of switching speed to the conventional solutions, i.e., the capability of operating at a sub-nanosecond speed or faster. In addition, signal frequency reconfigurability is also a desirable feature to facilitate new innovations of flexible system functions. Utilizing microwave photonics as an alternative path, we present here a photonic implementation of an RF switch providing not only the capability of switching at a sub-nanosecond speed but also options of frequency doubling of the input RF signals, allowing for flexible output waveforms. The core device is a traveling-wave silicon modulator with a device size of 0.2 mm × 1.8 mm and a modulation bandwidth of 10 GHz. Using microwave frequencies, i.e., 15 GHz and 20 GHz, as two simultaneous RF input signals, we experimentally demonstrated their amplitude and frequency switching as well as that of the doubled frequencies, i.e., 30 GHz and 40 GHz, at a switching frequency of 5 GHz. The results of this work point to a solution for creating high-speed RF switches with high compactness and flexibility.

Dual-wavelength random distributed feedback fiber laser with wavelength, linewidth, and power ratio tunability.

Owing to the special power distribution property, a random distributed feedback Raman fiber laser can achieve a high power spectrally flexible output with a low power spectrally tuning device. Here, an all-fiberized linearly polarized dual-wavelength random distributed feedback Raman laser with wavelength, linewidth, and power ratio tunability is demonstrated. By adopting two watt-level bandwidth adjustable optical filters, a spectrum-manipulable dual-wavelength output with nearly a 10 W output power is achieved. The wavelength separation can be tuned from 2.5 to 13 nm, and the 3 dB linewidth of the output can be doubled by increasing the bandwidth of the optical filter. The power ratio of each laser line can be tuned from 0 to nearly 100% with the help of two variable optical attenuators. A maximum output power of 9.46 W is realized, with a polarization extinction ratio up to 20.5 dB. The proposed dual-wavelength fiber laser can be employed as a pump source in frequency tunable, bandwidth adjustable terahertz microwave generation, and mid-infrared optical parametric oscillators.

A High-Performance LDO Regulator Enabling Low-Power SoC With Voltage Scaling Approaches

Low-power system-on-a-chip (SoC) with multiple voltage domains often adopts voltage scaling approaches to optimize power usage while maintaining enough performance. Voltage regulators having flexible output configurability, fast transient response, and high-power noise rejection ability are indispensable for this application scenario. A low-dropout (LDO) regulator was proposed in this article to convert an input of 1.9–1.1 V to an output of 1.1–0.2 V with a 10-mV tuning resolution by raising the concept of programmable recursively divide-by-two resistor array (PRDTRA). A high gain-bandwidth main regulation loop of the proposed LDO regulator was accompanied by a transient acceleration (TA) path and a unity power noise gain generator to achieve a 28-mV output variation during 0–100-mA load transient test while keeping a 60-dB power supply rejection ratio (PSRR) over a frequency band of 0–1 MHz. Performance evaluations show the performance superiority of the proposed LDO regulator.

A Novel Microstrip Line Balun With Transparent Port Impedance and Flexible Open Arm Structure

In this letter, a novel microstrip line balun with transparent port impedance and unconnected flexible output arms is presented. The proposed balun is designed from a symmetric four-port device with an open end at its isolation port. To achieve balun function, a shunt stub is attached between the unbalanced port and the virtual open-ended port to generate a transmission zero under the even-mode circuit. Its odd-mode circuit is treated as an impedance transformer, where the transformer is independent of the terminal impedance. In addition, the proposed balun has flexible open arm branches and does not require a closed loop structure, which provides design flexibility to integrate with other devices compared to conventional closed-loop branch line baluns. The theoretical design equations are derived first to prove the design concept. Then, two prototypes are designed with 35 $\Omega $ system impedance and loaded with 50 and 75 $\Omega $ port impedance, and the measured results match well with the simulation, which further validates the proposed design theory.

Design of Arbitrary-Phase-Difference Transdirectional Coupler and Its Application to a Flexible Butler Matrix

In this article, an arbitrary-phase-difference (A-PD) transdirectional (TRD) coupler is proposed and applied in the design of a flexible Butler matrix. The A-PD TRD coupler, which also features the characteristics of arbitrary power division and miniaturized size, is composed of four sections of coupled lines and four types of capacitors. Explicit equations for designing the A-PD TRD coupler were derived utilizing the even–odd mode decomposition analysis, and guidelines to obtain the circuit parameters were also given. To demonstrate the design procedure, examples of the proposed coupler are provided and the relevant studies on the coupler’s electrical parameters are conducted. By combining the proposed coupler with the TRD coupled-line-based crossovers and the −45° phase shifters, a miniaturized $4 \times 4$ Butler matrix with flexible output ports phase differences (−25°, 155°, −115°, and 65°) is implemented. It inherits the features of the TRD coupler including A-PD and compact size. At the center frequency, the measured amplitude and phase imbalances are less than 1.4 dB and 3.2°, respectively, between the output signals. Compared to state-of-the-art A-PD-coupler-based Butler matrix, the proposed structure shows a smaller size ( $1.35 \lambda _{g} \times 1.36 \lambda _{g}$ ) and a wider bandwidth (20%).

Mutplot: An easy-to-use online tool for plotting complex mutation data with flexibility.

With the development of technology, an enormous amount of sequencing data is being generated rapidly. However, transforming this data into patient care is a critical challenge. There are two difficulties: how to integrate functional information into mutation interpretation and how to make the integration easy to apply. One solution is to visualize amino acid changes with protein structure and function in web app platform. There are multiple existing tools for plotting mutations, but the majority of them requires programming skills that are not common background for clinicians or researchers. Furthermore, the recurrent mutations are the focus and the recurrence cutoff varies. Yet, none of the current software offers customer-defined cutoff. Thus, we developed this user-friendly web-based tool, Mutplot (https://bioinformaticstools.shinyapps.io/lollipop/). Mutplot retrieves up-to-date domain information from the protein resource UniProt (https://www.uniprot.org/), integrates the submitted mutation information and produces lollipop diagrams with annotations and highlighted candidates. It offers flexible output options. For data that follows security standards, the app can also be hosted in web servers inside a firewall or computers without internet with Uniprot database stored on them. Altogether, Mutplot is an excellent tool for visualizing protein mutations, especially for clinicians or researchers without any bioinformatics background.

High-Performance and Cost-Effective ZCS Matrix Resonant Inverter for Total Active Surface Induction Heating Appliances

Flexible cooking surfaces represent the most innovative and high-performance induction heating appliances nowadays. This paper presents a multiple-output resonant inverter for multicoil systems featuring high efficiency and flexible output power control for modern induction heating appliances. By adopting a matrix structure, the number of controlled devices can be significantly reduced while high control versatility is ensured. The proposed converter is first analyzed and, in order to prove the feasibility of the proposal, a multiple-output prototype is designed and implemented. The experimental results prove the correct converter operation and output power control with multiple induction heating loads, validating the proposed approach.

Towards improved port capacity investment decisions under uncertainty: a real options approach

ABSTRACTPort activity plays an important role in facilitating international trade. Sufficient capacity is indispensable for a port to attract flows to a region and retain them. The capacity decision is the result of a trade-off between investment and waiting costs. Traditional methods to value expansion projects do not deal adequately with managerial flexibility in the face of uncertainty from different sources in the complex port environment. In this paper, real options (RO) models are identified as an alternative method to making project valuations and investment decisions, as they attribute the correct value to managerial flexibility under uncertainty. In order to be able to build and use such RO models for port capacity investment decisions, the sources and implications of uncertainty in the port and the different RO model specifications need to be understood. To this end, both the literature about uncertainty in the port context and the literature about real options models are reviewed in order to provide researchers who want to build their own decision-making models, with the necessary knowledge of both fields. The review makes clear that the complex interactions in and competition between the logistics chains and their actors coming together in ports have significant impacts on port capacity. Uncertainty is also caused by uncertain international trade flows and changes in legislation following new technologies and environmental impacts. An analysis of the components of some general RO models shows how the options of flexible output, investment size and timing are valued by RO models in a setting with demand uncertainty. Moreover, the review presents researchers with insights in how to deal with cooperative and competitive interactions in the chain, time to build, cyclical markets and legislation changes. It also shows how to value the expansion and the phased investment options. The new insights resulting from this review are subsequently combined in a framework that serves as a guideline to build RO models for port capacity investments. Finally, an exemplifying application of the framework is used to build an actual port capacity investment decision model.

Kinematics Modeling and Simulation of GantryShip Welding Manipulator with Hybrid Structure

The existing gantry ship welding robot mechanism is mostly in series, which has the problems of large motion inertia at the end and joint error accumulation.A kind of ship welding robot with hybrid structure is designed. The platform control mechanism and rotary mechanism adopt the form of planar parallel mechanism, which can effectively increase the rigidity and error compensation ability of the actuator.And the adjusting mechanism of welding torch adopts series structure and keeps the flexible output ability.The kinematics model of the welding actuator is established by combining the closed-loop vector method, complex vector method and D-H four-parameter method.The positive solution of the mechanism is given, and the velocity and acceleration are analyzed based on it.Through simulation analysis, we get the workspace and kinematic characteristics curve of some components under given trajectories to verified the feasibility of the proposed mechanism.

Involuntary Unemployment in a Neoclassical Growth Model with Public Debt and Human Capital

Abstract Even more than eight decades since the publication of Keynes’ “General Theory of Employment, Interest, and Money” modern macroeconomists disagree on the notion of “underemployment equilibrium” with so-called “involuntary unemployment”. While the majority of macro theorists trace involuntary unemployment back to frictions and rigidities in the adaptation of wages and output prices to market imbalances, a minority position holds that even under perfectly flexible output prices and wage rates involuntary unemployment might occur. Morishima in “Walras’ Economics” and more recently Magnani presume that contrary to the majority view aggregate investment is not perfectly flexible but governed by “animal spirits” of investors. The aim of the present paper is to integrate the Morishima-Magnani approach into a Diamond-type overlapping generations’ (OLG) model with internal public debt subsequently extended by human capital accumulation. It turns out that in spite of perfectly flexible real wage and interest rate involuntary unemployment occurs in intertemporal general equilibrium when aggregate investor sentiments are too pessimistic regarding the rentability of investment in real capital. In the model extended by human capital a higher public debt to output ratio decreases unambiguously involuntary unemployment, if initially the endogenous output growth rate is higher than the real interest rate.

Dynamic performance analysis of a high-temperature steam electrolysis plant integrated within nuclear-renewable hybrid energy systems

A high-temperature steam electrolysis (HTSE) plant is proposed as a flexible load resource to be integrated with a light water reactor (LWR) in nuclear-renewable hybrid energy systems (N-R HESs). This integrated energy system is capable of dynamically apportioning electrical and thermal energy on an industrial scale to meet both grid demand and energy needs in the HTSE plant without generating greenhouse gases. A dynamic performance analysis of such a system is carried out to evaluate its technical feasibility and benefits, and safety operating under highly variable conditions requiring flexible output. To support the dynamic analysis, special emphasis is given here to the modeling and control design of the HTSE process, which employs planar solid oxide electrolysis cells, coupled to an LWR. The proposed model includes practical constraints, such as operating limits of equipment, and allows the simulation of transient response of the LWR/HTSE integration case with high penetration of renewable resources. Simulation results involving several case studies show that the HTSE integrated N-R HESs could lead to efficient utilization of clean energy generation sources at levels that maximize profits, i.e., steady-state operation of a nuclear reactor and high penetration of solar or wind energy without curtailment, by providing dispatchable electricity to the grid and producing alternative value-added products (hydrogen and oxygen). The results also indicate that the system can provide various types of ancillary services (i.e., regulation, operating reserves, and load following) to support grid stability while satisfying its operating constraints and control objectives; thus, it is capable of effectively and economically mitigating the increasing levels of dynamic variability and uncertainty introduced by renewables.