Remote Generation Research Articles

Turbulence-enhanced THz generation by multiple chaotically-distributed femtosecond filaments in air

Remote generation of electromagnetic waves in the terahertz (THz) by the volume of air medium gains increasing scientific interest due to the demand for this spectral range in solving various practical problems including those belonging to the nonlinear atmospheric optics. During self-focusing and filamentation of high-power femtosecond laser pulses in air, the source of THz radiation is the plasma of laser filaments. One of the main challenges of THz generation by a laser filament is increasing the value of optical energy conversion to the long-wavelength band. In this paper, we present the results of our studies on DC-biased THz generation during single-color filamentation in air of focused femtosecond Ti:Sapphire-laser pulses (800 nm, pulse energy up to 40 mJ). The distinctive feature of our study is that a femtosecond optical pulse propagates through a spatially-localized heated air layer containing randomly inhomogeneous refractive index perturbations, which mimics strong air turbulence. For the first time to our knowledge, we show, that the turbulent air layer formed at the beginning of the optical path allows increasing the yield of THz radiation up to 1.5 times due to the formation of multiple chaotically-arranged filaments resulting from random perturbations of the optical beam energy profile that reduces the subsequent THz (re)absorption in the filament plasma.

Computational modeling of a surfatron mode microwave plasma in NH3/N2 for remote radical generation in a silicon native oxide cleaning process

Plasma-produced NxHy radicals facilitate the removal of native oxide layers in a semiconductor wafer surface. A remote microwave excited plasma with a NH3–N2 feed gas is used commonly to produce the active radicals. We perform a three-dimensional modeling of a microwave excited plasma operating in a surfatron mode. The device consists of a rectangular waveguide intersecting a quartz tube through which the feed gas flows. We discuss the propagation of a polarized 2.45 GHz microwave from the waveguide into the quartz tube where power is deposited into the plasma. The plasma–wave interaction is found to be highly three dimensional, with a propagating surface mode of the wave established along the dielectric tube plasma interface. Significant heating occurs on the side of the tube that directly faces the incident wave. As the flow carries the plasma-produced species down the tube, species radial profiles become increasingly diffusion controlled and axisymmetric. The dominant radicals that exit the tube are H2 and NH2, with nearly complete conversion of the feed gases to product species. The gas temperature rises above this inlet feed gas temperature and increases with increasing wave power. However, the gas temperature increase is not consequential to the overall radical yield from the plasma. The parametric study with changing pressure and input power illustrates the role of specific chemical reactions in the overall remote plasma process.

Optically mediated remote entanglement generation in magnon-cavity systems

Optically mediated remote entanglement generation in magnon-cavity systems

Fuel ignition using remote generation of microwave plasma in air at atmospheric pressure

The high demand for a new ignition device for aeronautical engines has motivated the study on an innovative microwave approach, presented in this paper. A dedicated experimental set-up is presented in which we demonstrate the successful ignition of a kerosene spray by a remotely excited microwave plasma. This plasma is created in a Split Ring Resonator (SRR) gap, placed in a copper cavity, in air at atmospheric conditions at the frequency of f = 2.8467 GHz and a pulsed power injected into the cavity of Pcav ≈ 1500 W.

Characterizing water transfer in compacted soils in the context of energy storage, contribution of magnetic resonance imaging (MRI)

The concept of energy geostructures consists in enhancing existing civil engineering structures from an energy point of view thanks to the insertion of heat exchanger tubes. In order to consider the use of compacted soil embankments for heat storage [1], a good knowledge of water movement is required. Indeed, the increase in temperature of the exchangers leads to a migration of liquid/vapour water to the surface layers [2]. A loss of moisture may alter the thermal capacity of the soil [1] and therefore the system energy efficiency. To determine unsaturated hydraulic properties, the Instantaneous Profile Method (IPM) consists in inducing transient flow in a long cylindrical sample of soil and then measuring the resulting water content and/or pore water pressure profiles at various time intervals [3]. The unsaturated hydraulic conductivity (ku) is then computed using Darcy’s law.
 The direct evaporation technique allows the measurement of the suction profile in a soil column submitted to drying [4] using filter papers whose water retention curve is known. This method is quite reliable but requires long equilibrium time. Thus, the tests need several weeks and do not give accurate results at the early stages of drying, as the soil state is close to saturation. The analysis of the results when the soil retention capacity is low is therefore complicated, especially when the flow is coupled with temperature variations.
 In this study, this classical method was compared to a faster alternate method using nuclear magnetic resonance imaging (MRI) that allows for non-intrusive, continuous and small-scale monitoring of the effect of thermo-hydraulic solicitations on water transfer within the sample. The use of MRI for monitoring the drying/wetting front progression appeared in 1970 [5]. Simpson et al. [6] presented the successive studies that have made it possible to develop a method for monitoring the movement of water within a sample. These measurements can be 1D, 2D and 3D.
 The tests were performed on a sandy lean clay sampled in the Paris region in France. The soil was dried, pulverized, and sieved through a 2 mm sieve before experiments. The compaction state was selected to optimize the heat storage capacity [4] with a water content of 16.3% and a dry density of 1.79 Mg.m-3. Ten cylindrical samples of 70 mm in diameter and 20 mm in height were compacted and superimposed with introducing filter paper disks between them. The regular weighting of each sample and each filter paper during three months allowed the derivation of the ku curve by the IPM method.
 For the MRI method, 9 samples of 36 mm in diameter and 10 mm in height were compacted at the initial state then brought to different degrees of saturation. The measurement of the water proton relaxation time using a Bruker Biospec 24/40 superconducting magnet (100 MHz), allowed the definition of a calibration curve which connects MRI signal to the water content of the samples (Figure 1b). A Single Point Imaging pulse sequence [7] was used to obtain the signal intensity (encoding time 75 µs < t < 200 µs). In an image acquired with the SPI method, the intensity of each voxel (S) is :
 (1) Whereis the magnetization in a pixel and is the transverse relaxation time.
 The calibration curve is shown in Figure 1b. Then, a larger sample of 30mm in height was compacted and exposed to an air flow at 20°C and 30% relative humidity through using a remote humid air generation system. 27 measurements points were monitored with an interval of 1.1 mm along the sample. Four examples of the recorded profiles are shown in Figure 1c. The evolution of the water content inside the sample is then calculated using the calibration curve to interpret the water migration in the samples submitted to humidity- and temperature-controlled air (Figure 1a). The pre-established retention curve of the soil will be used to calculate its matric suction. At each depth, the flow velocity and the hydraulic gradient will be calculated from the water content profiles and suction profiles respectively in order to determine the unsaturated hydraulic conductivity. 
 These experimental developments allow the non-intrusive and continuous quantification of water movement in unsaturated soils during the application of coupled thermo-hydraulic solicitations. The understanding of these fundamental parameters is a key step for studying thermo-hydromechanical behavior of compacted soils considered for heat storage. The results provide insight into the feasibility of these structures in terms of their long-term energy efficiency and stability.

Coupled three-mode squeezed vacuum: Gaussian steering and remote generation of Wigner negativity

Coupled three-mode squeezed vacuum: Gaussian steering and remote generation of Wigner negativity

Zipper arguments and duties regarding future generations

Most of us believe that it would be unjust to act with indifference about the plight of future generations. Zipper arguments in intergenerational justice aim to show that we have duties of justice regarding future generations, regardless of whether we have duties of justice to future generations. By doing so, such arguments circumvent the foundational challenges that come with theorising duties to remote future generations, which result from the non-existence, non-identity and non-contemporaneity of future generations. I argue that zipper arguments face several significant challenges. The ought-implies-can challenge points out that because prior generations determine what later generations can transfer, they determine how much they ought to transfer. In addition, both intentional and non-intentional non-compliance can break the chain of duties towards future generations on which zipper arguments rely. Some versions are surprisingly resilient especially in real-world circumstances. This paper does not show that zipper arguments inevitably fail, but all ways forward come at significant theoretical costs. Unless the challenges posed here are met (or shown as irrelevant), theorists of justice cannot side-track the foundational challenges that come with doing intergenerational justice.

Synthesis of Substituted Indolines through Photocatalyzed Decarboxylative Radical Arylation.

We report a new photocatalyzed remote alkyl radical generation and cyclization to prepare substituted indolines in a green, metal-free procedure. This method complements the Fischer indolization, metal-catalyzed couplings, and photocatalyzed radical addition and cyclization. A wide range of functional groups is tolerated, including aryl halides, that would not be compatible with most existing methods. Electronic bias and substitution were studied to demonstrate complete regiocontrol and high chemocontrol in the indoline formation.

Protection scheme for multi-terminal HVDC system with superconducting cables based on artificial intelligence algorithms

This paper presents the development of a novel data-driven fault detection and classification scheme for DC faults in multi-terminal HVDC transmission system which incorporates superconducting cables and modular multi-level converters. As the deployment of superconducting cables for bulk power transmission from remote renewable generation is progressively increasing in the future energy grids, many fault-related challenges have been raised (i.e., fault detection, protection sensitivity/stability). In this context, the applications of Artificial Intelligence techniques have started to be considered as a powerful tool for the development of robust fault management solutions. The proposed artificial intelligence-based method utilizes local current and voltage measurements to detect and classify all types of faults on the DC cables and DC buses, without the requirement of measurements exchange among different DC substations. The performance of the proposed scheme has been assessed through detailed transient simulation analysis and the results confirmed its effectiveness against a wide range of fault conditions (i.e., various fault types, fault locations and fault resistances). Furthermore, the feasibility of the developed scheme for real-time implementation has been validated using real-time software in the loop testing. The results revealed that the proposed algorithm can correctly, and within a very short period of time (i.e. less than 2 ms) detect and classify the faults within the protected zone and concurrently remain stable during external faults. Additionally, the generalization capability of the algorithm has been verified against influencing factors such as the addition of noise, highlighting the robustness of the presented scheme.

Optimum combination of diesel and concentrating solar in remote area power generation using supercritical CO2 turbines

Electrification of remote communities is a great challenge worldwide. Their reliance on economically and environmentally unfavourable diesel generators makes these communities attractive target markets for renewables. Concentrating solar thermal (CST) plants operating on supercritical CO2 (s-CO2) Brayton power cycles have been proposed for their high efficiency, compactness, compatibility with natural air-cooling, and capability of being built at a small size without significant efficiency penalties. Thermal energy storage (TES) technology can mitigate intermittency problems. This study aims to identify the optimal configuration of hybrid CST and diesel generation (DG) for different types of remote locations based on annual simulations involving key system design features including solar multiple, TES size, and CST size. One novelty in this study is the inclusion of actual weather information and load demand profiles for selected potential locations. Another is that a realistic economic model for s-CO2 power blocks for small to medium sizes, based on accurate cost data, is presented. More importantly, a realistic representation of the s-CO2 turbine, which includes isentropic efficiencies varying at off-design conditions, is used. This facilitates a study into the effects that the inclusion of realistic off-design turbine information has on the thermodynamic and techno-economic performances of the system. This is done by comparing the simulation results with results obtained using a conventional method that uses a constant turbine efficiency. This paper presents the optimal system configurations offering the lowest levelised cost of energy (LCOE) obtained using three-variable exhaustive search optimisation. The results show that the system is an economically favourable option and provides substantial environmental benefits.

Polarization–orbital angular momentum duality assisted entanglement observation for indistinguishable photons

Duality in the entanglement of identical particles manifests that entanglement in only one variable can be revealed at a time. We demonstrate this using polarization and orbital angular momentum (OAM) variables of indistinguishable photons generated from parametric down-conversion. We show polarization entanglement by sorting photons in even and odd OAM basis, while sorting them in two orthogonal polarization modes reveals the OAM entanglement. Indistinguishable photons entangled in two variables could find applications in robust quantum communication, remote entanglement generation and distributed quantum sensing.

Fiber-based 3D nano-printed holography with individually phase-engineered remote points

The generation of tailored light fields with spatially controlled intensity and phase distribution is essential in many areas of science and application, while creating such patterns remotely has recently defined a key challenge. Here, we present a fiber-compatible concept for the remote generation of complex multi-foci three-dimensional intensity patterns with adjusted relative phases between individual foci. By extending the well-known Huygens principle, we demonstrate, in simulations and experiments, that our interference-based approach enables controlling of both intensity and phase of individual focal points in an array of spots distributed in all three spatial directions. Holograms were implemented using 3D nano-printing on planar substrates and optical fibers, showing excellent agreement between design and implemented structures. In addition to planar substrates, holograms were also generated on modified single-mode fibers, creating intensity distributions consisting of about 200 individual foci distributed over multiple image planes. The presented scheme yields an innovative pathway for phase-controlled 3D digital holography over remote distances, yielding an enormous potential application in fields such as quantum technology, life sciences, bioanalytics and telecommunications. Overall, all fields requiring precise excitation of higher-order optical resonances, including nanophotonics, fiber optics and waveguide technology, will benefit from the concept.

The Ideation Compass: supporting interdisciplinary creative dialogues with real time visualization

ABSTRACT This study presents the potential of live topic visualization in supporting creative dialogs during remote idea generation. We developed a novel Creativity Support Tool (CST) to explore the effects of the live topic visualization. The tool emphasizes the interdisciplinary knowledge background of participants. Using Natural Language Processing (NLP) and topic modeling, the tool provides users with a live visual mapping of the domains and topics being orally discussed. To understand the tool’s user perceived effects, we conducted evaluation sessions and interviews with participants (N = 10) from two different disciplinary backgrounds: design and bioscience. The findings show that live visualization of domains and topics supported self-reflection during individual and collaborative creativity and encouraged a balanced discussion, which can mitigate discipline-based fixation in ideation.

Characterization of nanosecond laser-induced underwater filamentation using acoustic measurements.

This investigation aims to understand the temporal and spectral characteristics of underwater acoustic impulses due to ∼10n s laser-induced filamentation at various incident laser energies. In addition to the experimental study, finite element analysis (FEA) has been used in conjunction with experimentally acquired data to simulate and visualize acoustic impulse propagation and interaction across the water-rigid boundary. In the time domain, the increase in the underwater filament length is measured by the peak-to-peak (P k-P k) overpressures as a function of input laser energies. The P k-P k overpressures are maximum around the focal plane and are symmetrical on either side. This variation in the P k-P k overpressure is traced to characterize the spatial extent of the underwater filament. The arrival time of underwater acoustic impulse varies within the 8-9µs for input laser energies. It was observed that with increasing laser beam power, the conversion efficiency of the acoustic impulse decreases, and the underwater filament length increases. In the frequency domain, with increasing input laser energy, the peak frequency of the underwater acoustic impulse shifts toward the lower frequencies. Using FEA, the short-time Fourier transform spectrogram simultaneously visualizes the arrival time and instantaneous frequency of the simulated acoustic impulse. The simulated acoustic impulse produced a single instantaneous peak frequency of around 76kHz. Upon reflection from the water-rigid boundary, we observed that the reflected signal also has a single instantaneous peak frequency of around 76kHz, while higher-frequency components are completely dissipated. Our results are promising for the development of remote laser-based acoustic generation and sensing applications.

Review of Various Transmission Loss Allocation Methods: A Case Study of Integrated Nepal Power System using Best Method

This paper presents a review of the most relevant and practical methods for allocating transmission loss in a deregulated market. They are the pro-rata (PR) method, the marginal allocation (ITL) method, the proportional sharing (PS) method, and the Z-Bus method. This study has also performed a qualitative comparison of four methods using the IEEE 14 bus system. Finally, the Z-Bus method is selected as the best option for implementation in the Integrated Nepalese Power System Network (INPS). As of 2022, the loss allocation is determined at all 132 and 220 kV substations of INPS. The study of transmission loss allocation for INPS is carried out for six different cases, considering the variation in patterns of energy generation and demand, i.e., system full generation, summer peak, winter peak, average peak, dry peak, and contingency condition. The result shows the load, like Kathmandu Valley, which is in the region of generation, and the generator, like in the eastern region, which is in the region of demand, are mostly compensated with negative losses. Loads in the western region and generators like the Upper Tamakhoshi, which are far from the generator or load, are assigned the highest positive loss. Loss allocation to load and generator can vary depending on the loading conditions that INPS is operating under. The generation is comparably distributed in the full generation, summer, and contingency instances; as a result, the loss allocation to both loads and generators is significant. However, the bulk of losses are only attributed to the generator side in the three other scenarios with less generation, when the majority of the generation is only aggregated in a specific location. This is a result of the remote generator's long-distance power flow, which raises system loss. As a result, the Z-Bus method assigned the generator side the majority of the losses. Additionally, the majority of INPS's generation is determined to be remotely located, which increases their risk of transmission loss. Because of this, INPS is best served by the Z-Bus approach, which takes into account the locations of buses within the network. In order to minimize system loss, this encourages big demand or generation to be positioned close to the center of generation or demand.

Reverse wavefront engineering for remote generation of a near-infrared femtosecond Bessel beam filament in air

Precise control of the filamentation of an ultrashort and intense near-infrared laser pulse in air is crucial for many applications but remains challenging. By combining inverse design for shaping of a pulse at the output of a laser with simulation of the nonlinear propagation of the pulse in air, we numerically investigate the way to simultaneously control the length and position of a plasma filament at an arbitrary remote distance for the first time. An intermediate state, with a Bessel-Gauss beam profile, is introduced between the laser output and the filament. Through forward and backward propagations of the intermediate state, an end-to-end design of the initial laser pulse is achieved to match the desired filament characteristics. Our calculations show that a properly engineered torus pulse can project such a Bessel-Gauss beam at remote distance and generate a long plasma filament without requiring any feedback loop. We also proposed an experimental arrangement to project such an intermediate state and generate the corresponding filament remotely. The method can be further extended to other types of filaments or targets that may be reached from different intermediate states.

Giant thermoelectric power in fluorine-doped single-walled carbon nanotubes

Herein, we report on a tunable axial thermoelectric power (TEP), in a non-degenerate fluorine-doped single-walled carbon nanotubes (FSWCNTs) as calculated for carriers in the lowest miniband using a tractable analytical approach. We deduced the axial thermoelectric power (αzz) as a function of temperature gradient (∇T). Additionally, we investigated the influence of doping concentration (no), constant electric field (Eo), and overlapping integral for jumps (Δs and Δz) on their behaviour. The intensity of the axial thermoelectric power (αzz) and the operational temperature range could be tuned using the constant electric field, doping and overlapping integrals, respectively. It is worth noting that the giant thermoelectric power (αzz) obtained and the ability to tune the FSWCNT to operate at high temperatures make FSWCNT a potential candidate for thermoelectric applications such as remote power generation.

An architecture for quantum networking of neutral atom processors

Development of a network for remote entanglement of quantum processors is an outstanding challenge in quantum information science. We propose and analyze a two-species architecture for remote entanglement of neutral atom quantum computers based on integration of optically trapped atomic qubit arrays with fast optics for photon collection. One of the atomic species is used for atom-photon entanglement, and the other species provides local processing. We compare the achievable rates of remote entanglement generation for two optical approaches: free space photon collection with a lens and a near-concentric, long working distance resonant cavity. Laser cooling and trapping within the cavity removes the need for mechanical transport of atoms from a source region, which allows for a fast repetition rate. Using optimized values of the cavity finesse, remote entanglement generation rates $> 10^3~\rm s^{-1}$ are predicted for experimentally feasible parameters.

Remote Power Generation for Applications to Natural Gas Grid: A Comprehensive Market Review of Techno-Energetic, Economic and Environmental Performance

The operation of natural gas grids requires electric-powered devices as data acquisition and control systems, surveillance and communication appliances, etc., often located in remote, unpopulated off-the-grid areas, where there is no personnel for surveillance, and maintenance costs are prohibitive. The literature on the power generating systems for these devices is limited to specific applications without a comparison between competing technologies, making their choice a difficult task for natural gas operators. This work presents a comprehensive up-to-date survey of market available technologies for remote power generation in the range of 20–1000 W for gas grid applications: thermoelectric generators, solid acid, direct methanol and solid oxide fuel cells, Stirling engines and microturbines. The work aims at sorting the technologies by techno-energetic, economic and environmental performance while providing specific technological characteristics and limitations. The results indicate well-defined ranges of power in which only some of the technologies are suitable and have very different efficiencies (3–30%). The capital cost of equal power technologies is similar (EUR 5000–30,000) and roughly linear with power (34.8Pel + EUR 6553), whereas operation costs (10–120 cEUR/kWh) and lifetime (0.5–20 yr) significantly depend on the technology. The indications of this review may constitute helpful guidelines to choose properly power generation systems for remote applications.

NetQASM—a low-level instruction set architecture for hybrid quantum–classical programs in a quantum internet

We introduce NetQASM, a low-level instruction set architecture for quantum internet applications. NetQASM is a universal, platform-independent and extendable instruction set with support for local quantum gates, powerful classical logic and quantum networking operations for remote entanglement generation. Furthermore, NetQASM allows for close integration of classical logic and communication at the application layer with quantum operations at the physical layer. This enables quantum network applications to be programmed in high-level platform-independent software, which is not possible using any other QASM variants. We implement NetQASM in a series of tools to write, parse, encode and run NetQASM code, which are available online. Our tools include a higher-level software development kit (SDK) in Python, which allows an easy way of programming applications for a quantum internet. Our SDK can be used at home by making use of our existing quantum simulators, NetSquid and SimulaQron, and will also provide a public interface to hardware released on a future iteration of Quantum Network Explorer.