Conventional Schemes Research Articles

Pattern effect suppression of pulse signals based on pre-signal control method

By using the pre-signal light as the control light, we propose a method to suppress the transient effect of erbium-doped fiber amplifiers for low-frequency pulse signals. The pattern effect of the pulse signals within the low frequency range (400–1000 Hz) and 1550 nm band is relieved, and the optical surge coefficient Cs decreases to about 0.54 dB. Experimental results show that the proposed method has better performances in suppressing pattern effect in comparison with the conventional continuous light control scheme and higher output gain compared to the compensation pulsed light method. Our proposed pattern effect suppression approach based on the pre-signal control method is anticipated to find promising applications in the field of optical communications.

Heat and Flow Characteristics of Aerofoil-Shaped Fins on a Curved Target Surface in a Confined Channel for an Impinging Jet Array

The main purpose of this investigation was to explore the heat transfer and flow characteristics of aero-foil-shaped fins combined with extended jet holes, specifically focusing on their feasibility in cooling turbine blades. In this study, a comprehensive investigation was carried out by applying impinging jet array cooling (IJAC) on a semi-circular curved surface, which was roughened using aerofoil-shaped fins. Numerical computations were conducted under three different Reynolds numbers (Re) ranging from 5000 to 25,000, while nozzle-to-target surface spacings (S/d) ranged from 0.5 to 8.0. Furthermore, an assessment was made of the impact of different fin arrangements, single-row (L1), double-row (L2), and triple-row (L3), on convective heat transfer. Detailed examinations were performed on area-averaged and local Nusselt (Nu) numbers, flow properties, and the thermal performance criterion (TPC) on finned and smooth target surfaces. The study’s results revealed that the use of aerofoil-shaped fins and the reduction in S/d, along with surface roughening, led to significant increases in the local and area-averaged Nu numbers compared to the conventional IJAC scheme. The most notable heat transfer enhancement was observed at S/d = 0.5 utilizing extended jets and the surface design incorporating aerofoil-shaped fins. Under these specific conditions, the maximum heat transfer enhancement reached 52.81%. Moreover, the investigation also demonstrated that the highest TPC on the finned surface was achieved when S/d = 2.0 for L2 at Re = 25,000, resulting in a TPC value of 1.12. Furthermore, reducing S/d and mounting aerofoil-shaped fins on the surface yielded a more uniform heat transfer distribution on the relevant surface than IJAC with a smooth surface, ensuring a relatively more uniform heat transfer distribution to minimize the risk of localized overheating.

Targeted optimization in small-scale atomic structure calculations: application to Au I

The lack of reliable atomic data can be a severe limitation in astrophysical modelling, in particular of events such as kilonovae that require information on all neutron-capture elements across a wide range of ionization stages. Notably, the presence of non-orthonormalities between electron orbitals representing configurations that are close in energy can introduce significant inaccuracies in computed energies and transition probabilities. Here, we propose an explicit targeted optimization (TO) method that can effectively circumvent this concern while retaining an orthonormal orbital basis set. We illustrate this method within the framework of small-scale atomic structure models of Au I, using the Grasp2018 multiconfigurational Dirac–Hartree–Fock atomic structure code. By comparing to conventional optimization schemes we show how a TO approach improves the energy level positioning and ordering. TO also leads to better agreement with experimental data for the strongest E1 transitions. This illustrates how small-scale models can be significantly improved with minor computational costs if orbital non-orthonormalities are considered carefully. These results should prove useful to multi-element atomic structure calculations in, for example, astrophysical opacity applications involving neutron-capture elements.

Robust parallel laser driving of quantum dots for multiplexing of quantum light sources

Deterministic sources of quantum light (i.e. single photons or pairs of entangled photons) are required for a whole host of applications in quantum technology, including quantum imaging, quantum cryptography and the long-distance transfer of quantum information in future quantum networks. Semiconductor quantum dots are ideal candidates for solid-state quantum emitters as these artificial atoms have large dipole moments and a quantum confined energy level structure, enabling the realization of single photon sources with high repetition rates and high single photon purity. Quantum dots may also be triggered using a laser pulse for on-demand operation. The naturally-occurring size variations in ensembles of quantum dots offers the potential to increase the bandwidth of quantum communication systems through wavelength-division multiplexing, but conventional laser triggering schemes based on Rabi rotations are ineffective when applied to inequivalent emitters. Here we report the demonstration of the simultaneous triggering of >10 quantum dots using adiabatic rapid passage. We show that high-fidelity quantum state inversion is possible in a system of quantum dots with a 15 meV range of optical transition energies using a single broadband, chirped laser pulse, laying the foundation for high-bandwidth, multiplexed quantum networks.

Dynamics of a strongly coupled quantum heat engine-Computing bath observables from the hierarchy of pure states.

We present a fully quantum dynamical treatment of a quantum heat engine and its baths based on the Hierarchy of Pure States (HOPS), an exact and general method for open quantum system dynamics. We show how the change of the bath energy and the interaction energy can be determined within HOPS for arbitrary coupling strength and smooth time dependence of the modulation protocol. The dynamics of all energetic contributions during the operation can be carefully examined both in its initial transient phase and, also later, in its periodic steady state. A quantum Otto engine with a qubit as an inherently nonlinear work medium is studied in a regime where the energy associated with the interaction Hamiltonian plays an important role for the global energy balance and, thus, must not be neglected when calculating its power and efficiency. We confirm that the work required to drive the coupling with the baths sensitively depends on the speed of the modulation protocol. Remarkably, departing from the conventional scheme of well-separated phases by allowing for temporal overlap, we discover that one can even gain energy from the modulation of bath interactions. We visualize these various work contributions using the analog of state change diagrams of thermodynamic cycles. We offer a concise, full presentation of HOPS with its extension to bath observables, as it serves as a universal tool for the numerically exact description of general quantum dynamical (thermodynamic) scenarios far from the weak-coupling limit.

Transformer faults identification via fuzzy logic approach

The need for a constant electricity supply is at an alarming rate especially in the 21st century due to the high rate of increase in industrialization across the globe. Conventional protection schemes such as differential relays, Buchholz relay, and other techniques such as genetic algorithms and artificial neural networks, do not match the precision and reliability needed for transformer fault indentification, due to their complexity in computation, tedious training system, time consumption, and need the of human experts. The method proposed in this research is the use of a fuzzy inference system in detecting potential faults in power system transformers. The faults in the transformer were observed and analyzed using a simulation system of MATLAB/Simulink software. The suggested approach ensures swift identification of faults as it relies on if-then rules and only uses current and voltage measurements with 100% independence toward the power flow direction, making it highly reliable and simple to implement compared to other techniques for transformer fault identification.

Univariate Flux Partition Functions for Planetary Boundary Layer Schemes at Gray Zone Resolutions

Abstract When the horizontal grid spacing of a numerical weather prediction model approaches kilometer scale, the so-called gray zone range, turbulent fluxes in the convective boundary layer (CBL) are partially resolved and partially subgrid scale (SGS). Knowledge of the partition between resolved and SGS turbulent fluxes is key to building scale-adaptive planetary boundary layer (PBL) schemes that are capable of regulating the SGS fluxes with varying grid spacing. However, flux partition depends not only on horizontal grid spacing, but also on local height, bulk stability of the boundary layer, and the particular turbulent flux. Such multivariate functions are difficult to construct analytically, so their implementations in scale-adaptive PBL schemes always involve certain levels of approximation that can lead to inaccuracies. This study introduces a physically based perspective for the flux partition functions that greatly simplifies their implementation with high accuracy. By introducing an appropriate scaling length λ that accounts for both height and bulk stability dependencies, the dimensionality of the partition functions is reduced to a single dimensionless group. Based on the analysis of a comprehensive large-eddy simulation dataset of the CBL, it is further shown that λ’s height and bulk stability dependencies can be separately represented by a similarity length scale and a stability coefficient. The resulting univariate partition functions are incorporated into a traditional first-order PBL scheme as a proof of concept. Our results show that the augmented scheme well-reproduces the SGS fluxes at gray zone resolutions. Significance Statement Flux partition functions are a key component in most scale-adaptive planetary boundary layer (PBL) schemes developed for kilometer- and subkilometer-resolution numerical weather prediction models. They regulate the parameterized turbulent fluxes as a function of horizontal grid spacing, while they also depend on height and atmospheric stability. Such multivariate dependencies forbid simple analytical expressions, and as a result, partition functions implemented in scale-adaptive PBL schemes are generally simplified at the cost of accuracy in previous works. This study investigates the possibility of constructing partition functions that are both accurate and easy to parameterize. Utilizing a physically based length scale, univariate partition functions are built, evaluated, and put into a conventional PBL scheme to improve the gray zone turbulence parameterization.

Pairwise Tomlinson-Harashima precoding for multiple-lane IM-DD transmissions.

As for the photonic interconnection based on the multiple-lane intensity modulation direct detection (IM-DD) transmission, both intra-channel inter-symbol-interference (ISI) originating from bandwidth constraint, and inter-channel performance discrepancy emerging from inter-channel component differences are the major bottleneck for the throughput enhancement. Here, we propose a pairwise Tomlinson-Harshima precoding (P-THP) scheme, in order to simultaneously deal with both intra-channel ISI and inter-channel performance discrepancy. The effective function of the proposed P-THP scheme is experimentally evaluated by transmitting 4-channel 81-GBaud PAM4 signals over 2 km standard single-mode fiber (SSMF). Compared with the conventional scheme with only applying THP on individual wavelength channel, the required optical received power (ROP) under the back-to-back (B2B) transmission can be reduced by 0.75∼1 dB with the help of proposed P-THP in different experimental component configurations, at the 7% hard decision forward error correction (HD-FEC) threshold of BER = 3.8 × 10-3. After the 2 km SSMF transmission, only the use of proposed P-THP can guarantee to reach the designated HD-FEC threshold, leading to a net rate of >600 Gbit/s.

A fast difference scheme for the multi-term time fractional advection–diffusion equation with a non-linear source term

In field experiments involving the movement of solutes through heterogeneous porous and fractured media, it has been observed that the contaminant plumes can transition between various diffusive states. This current research is dedicated to the development of a fast difference scheme designed for a multi-term time-fractional order advection–diffusion model that incorporates a nonlinear source term. This model is an instrumental tool in explaining the underlying dynamics of transport. To effectively address the substantial computational and storage challenges inherent in this problem, we present an efficient algorithm specifically designed for the fast computation of the Caputo derivative. This algorithm is based on the summation of exponentials technique. We thoroughly explore the theoretical aspects of our scheme including its unconditional stability and convergence with rigorous proofs. The proposed numerical scheme minimizes the CPU time and storage requirements when compared to the conventional direct difference scheme.

Precise determination of the top-quark on-shell mass via its scale- invariant perturbative relation to the top-quark mass * *Supported in part by the National Natural Science Foundation of China (12247129, 12175025, 12347101) and the Graduate Research and Innovation Foundation of Chongqing, China (ydstd1912)

The principle of maximum conformality (PMC) provides a systematic approach to solve the conventional renormalization scheme and scale ambiguities. Scale-fixed predictions of physical observables using the PMC are independent of the choice of renormalization scheme – a key requirement for renormalization group invariance. In this paper, we derive new degeneracy relations based on the renormalization group equations that involve both the usual β-function and the quark mass anomalous dimension -function. These new degeneracy relations enable improved PMC scale-setting procedures for correct magnitudes of the strong coupling constant and -running quark mass to be determined simultaneously. By using these improved PMC scale-setting procedures, the renormalization scale dependence of the -on-shell quark mass relation can be eliminated systematically. Consequently, the top-quark on-shell (or ) mass can be determined without conventional renormalization scale ambiguity. Taking the top-quark mass GeV as the input, we obtain GeV. Here, the uncertainties arise from errors combined with those from and the approximate uncertainty resulting from the uncalculated five-loop terms predicted through the Padé approximation approach.

An Adaptive Harmonic Separation Technique for Ultrasound Harmonic Imaging

ObjectiveAn adaptive harmonic separation (HS) technique is proposed to overcome the limitations in conventional filtering techniques for ultrasound (US) tissue harmonic imaging (THI). MethodsBased on expectation-maximization source separation, the proposed HS technique adaptively models the depth-varying fundamental and harmonic components in the frequency domain and separates the two by applying their calculated posterior probabilities. Phantom experiments with a Tx center frequency of 2 MHz are conducted to evaluate the proposed HS-based US THI schemes. ResultsThe phantom images show that the proposed single-pulse THI scheme utilizing the HS technique provides not only an average improvement of 19.2% in axial resolution compared to the conventional bandpass filtering scheme but also similar image quality to that of the conventional pulse-inversion (PI) scheme which requires two Tx/Rx sequences for each scan line. Furthermore, when combined with the PI technique, the HS technique provides a uniform axial resolution over the entire 170 mm imaging depth with an average improvement of 17.1% compared to the conventional PI scheme. ConclusionThese results show that the proposed adaptive HS technique is capable of improving both the frame rate and the image quality of US THI.

Reinforcement learning-based attitude control for a barbell electric sail

The electric solar wind sail (E-sail) is a new propellant-free propulsion concept. The under-actuated and highly nonlinear features of E-sail systems pose a great challenge to their attitude controller design. Conventional control schemes may not be capable of dealing with this tough problem. To this end, a reinforcement learning (RL)-based control scheme, which can explore and obtain optimal policies in the absence of training datasets, is proposed for the attitude control of a barbell E-sail system. The barbell E-sail comprises two end satellites linked to an insulated confluence point through long and conductive tethers. The voltages of the two tethers can be individually modulated for attitude control. The system attitude dynamics is described using a nonsingular formulation. The control scheme has a two-stage design. In the first stage, an RL controller based on the Proximal Policy Optimization (PPO) algorithm is used to obtain an RL control strategy, which is emulated and updated by neural networks. In the second stage, the attitude feedback control is accomplished with low computation and energy consumption and fast convergence speed by performing a real-time mapping from the system state to the control output using the updated control strategy. Finally, the simulation results demonstrate that the proposed RL-based control scheme can effectively adjust the E-sail to the design attitude by regulating the tether voltage difference. The comparisons with the NMPC scheme also indicate that the developed control scheme can significantly reduce the computation time with control accuracy maintained.

Parisi–Wu quantization, CP violation and beyond the standard model

The Parisi–Wu scheme of quantization opens up the possibility of using anomalous fermionic gauge theories. An analysis of ultra-violet divergences reveals that the structure of counter terms is different from what is expected in conventional quantization schemes. In this paper, it is argued that there exists a possible mechanism of CP violation that requires at least three generations of quarks, a result well known from a phenomenological analysis of mass mixing of quarks. A few observations on possible ways of going beyond the Standard Model are included.

Crystal-Structure Matches in Solid-Solid Phase Transitions.

The exploration of solid-solid phase transition suffers from the uncertainty of how atoms in two crystal structures match. We devised a theoretical framework to describe and classify crystal-structure matches (CSM). Such description fully exploits the translational and rotational symmetries and is independent of the choice of supercells. This is enabled by the use of the Hermite normal form, an analog of reduced echelon form for integer matrices. With its help, exhausting all CSMs is made possible, which goes beyond the conventional optimization schemes. In an example study of the martensitic transformation of steel, our enumeration algorithm finds many candidate CSMs with lower strains than known mechanisms. Two long-sought CSMs accounting for the most commonly observed Kurdjumov-Sachs orientation relationship and the Nishiyama-Wassermann orientation relationship are unveiled. Given the comprehensiveness and efficiency, our enumeration scheme provide a promising strategy for solid-solid phase transition mechanism research.

Multi-objective optimization for green logistics planning and operations management: From economic to environmental perspective

In the energy crisis and climate change context, the trade-off between economic and environmental objectives of green supply chain management and operations in industrial parks has become increasingly prominent. This paper couples the management of the energy generation, the refrigeratory inventory, and the cold-chain transportation systems of a green industrial park (GIP) for fresh goods that require low-temperature storage. We introduce the renewable energy microgrid (REM) to the energy chain and electric vehicles to the transportation system in the GIP to reduce carbon emissions. A two-phase multi-objective optimization model considering total expenditures and carbon emissions simultaneously is established to compare different renewable and conventional energy schemes. We exploit the real data to optimize scheduling strategies for energy, inventory, and fleet systems under a typical period based on different environmental conditions and time-sharing electricity prices. The empirical study shows that the adoption of REM and electrical vehicles can reduce carbon emissions in the supply chain by 13.6%, and GIP managers with different performance targets should choose different energy mixed schemes.

Fermented milk product “Narineh” with Lactobacillus acidophilus in sequential and classical therapy for Helicobacter pylori-associated peptic ulcers

Background: In recent years, there has been a growing dissatisfaction with the classical schemes of the eradication of Helicobacter pylori in ulcerative disease among physicians due to frequent failures in eradication therapy, mostly due to antibiotic resistance. It is a known fact that the Lactobacillus acidophilus inhibits the growth of Helicobacter pylori. Objective: Our main goal was to investigate the ability of the fermented milk product "Narineh,” as a functional food, containing Lactobacillus acidophilus to evaluate the efficiency and incidence of adverse effects in addition to the standard triple scheme of eradication therapy with colloidal bismuth substrate. Methods: The patients with peptic ulcer were divided into 2 groups: control (42 patients) received traditional treatment regimens, including 7 days proton pump inhibitor (PPI) + amoxicillin (A) and clarithromycin (C) in the standard doses and subsequent 14 day De-nol (colloidal bismuth subcitrate); experimental (44 patients) received in addition to this standard conventional scheme "Narineh" - 200g, containing 2x109 Lactobacillus acidophilus one time a day starting from the 8-th day for 4 weeks. The results of the eradication in patients were evaluated after 4 -5 weeks, 6 months, and 12 months after completion of treatment using the C13 respiratory urea test (RUT). Repeated endoscopy with histological biopsies was carried out together with RUT in 4-5 weeks after the completion of treatment, and later (6-12 months) for the identification of recurrent ulcer. Results: The treatment with “Narineh” added to the standard regimen significantly reduces the percentage of reinfection and relapse of the disease with a statistical difference (P<0,05). The combination of fermentation milk product “Narineh”, containing Lactobacillus acidophilus with bismuth subcitrate, doesn’t cause a violation of biocenosis of the large intestine, in contrast to the PPI and antibiotics with a statistical difference (P<0,05). In addition, it provides the normalization of gut biocenosis and reduces the frequency of antibiotic-associated diarrhea and other side effects. Conclusion: The treatment with “Narineh” added to the standard scheme is more effective for eradication of Helicobacter pylori infection and significantly reduces the percentage of reinfection and relapse of the disease and lessens the side effects of medications. Keywords: peptic ulcer, eradication Helicobacter pylori, side effects reinfection, fermented milk product “Narineh”, Lactobacillus acidophilus, functional foods

Parameter Identification for Maximum Torque per Ampere Control of Permanent Magnet Synchronous Machines under Magnetic Saturation

This paper applies the identified parameters of permanent magnet synchronous machines (PMSMs) for the maximum torque per ampere control (MTPA) under magnetic saturation. The variation in magnet flux with current is determined using a position offset approach while the variation in q-axis inductance with the current is estimated from the d-axis voltage equation afterward. In addition, the d-axis inductance is estimated at standstill by the injection of a small amplitude of high frequency d-axis current. The curve-fitted results of estimated parameters under different saturation conditions are then employed to aid the derivation of MTPA control law. The proposed method is experimentally verified on two prototype PMSMs. Experimental results show that compared with conventional MTPA schemes using fixed values of magnetic parameters, the proposed method can increase maximum output torque by 2.1% and 3.2% on two prototype PMSMs, respectively.

Dual-Phase-Shifted Pulsewidth Modulation of Three-Phase Modular Multilevel Converters

The modular multilevel converter (MMC) has been a crucial component for medium/high-power energy conversion systems due to its modular structure. In the literature, the harmonic analysis of MMC with different modulation methods, including the conventional carrier phase-shifted pulse width modulation (CPS-PWM) method, have been extensively investigated. However, the influence of the carrier displacement angles between three-phase legs on the output performance of an MMC is normally ignored. This paper proposes a dual-phase-shifted PWM (DPS-PWM) for a three-phase MMC which further enhances the performance of the conventional CPS-PWM scheme through proper selection of carrier displacement angles between three phases. First, the operation principle and implementation of the proposed DPS-PWM method is described. Then a two-dimensional (2D) Fourier model is derived to analyze how the carrier displacement angles between stacks and legs affect the harmonics of output voltage and circulating current. It is found that DPS-PWM can suppress specific harmonics in the line-to-line voltage by coordinating the carriers' phase shifting between the three-phase legs without affecting phase voltage and circulating current. Finally, the effectiveness of the DPS-PWM method is verified by simulation and experimental results.

Data-cell-variation-tolerant triple sampling non-destructive self-reference sensing scheme of STT-MRAM

Inevitable process variations (PVT) brought by both the magnetic tunneling junction (MTJ) and MOSFET based on the complementary metal-oxide semiconductor (CMOS) technology become a major obstacle for the mass production of spin transfer torque magnetic random access memory (STT-MRAM). The detriment of the process variations leads to a serious degradation in the fundamental yield with the shrinkage of the technology nodes. However, the conventional data-cell-variation-tolerant (DCVT) sense scheme cannot get the target read yield due to the limited sense margin (SM). To resolve this problem, a DCVT triple sampling non-destructive self-reference sensing scheme (TSNS) is proposed in the paper, which doubles the SM, with lower power consumption and better SM compared with the conventional DCVT sense scheme. Monte Carlo simulation with industry-compatible 65-nm model parameters results show that the proposed sensing scheme shows over 2.5 times higher SM and less power consumption compared to the previous self-reference circuit. The proposed sensing scheme can get the target read yield with lower power consumption.

Analyzing the relationship between the efficiency and safety of a turbo roundabout by the factor analysis method

The construction of cities and economic development lead to more and more serious environmental pollution, and the concept of green and low-carbon city has been proposed. Therefore, a series of requirements have been put forward for transportation. CO and other pollutants will be produced in the exhaust of conventional fuel vehicles, which will seriously affect the urban environment, especially at intersections with large passenger and vehicle flows. When multiple roads, especially more than 4 roads, intersect on urban roads, traffic organization can usually be achieved by using a roundabout. However, due to the limited capacity of the conventional roundabout, with the rapid increase of the traffic volume, and there are many vehicles in the circle lane change and interweaving behavior. This has caused serious congestion at the roundabout, the significantly increase in pollutants emissions and the decline in air quality. As an unconventional design, the turbo roundabouts use canalized traffic to allowed drivers to select the appropriate lanes in advance depending on their destinations so that different lanes within the circle do not interfere with one another, which improves the safety of the intersection while ensuring capacity. The main purpose of this paper is to analyze the traffic efficiency and safety of the conventional roundabout scheme and turbo roundabout scheme for five-way intersections. Using VISSIM to simulate different forms of roundabout and analyzing the six selected evaluation indicators. The number of vehicles in different entrance lanes and the diameter of the circle are selected as sensitivity factors for sensitivity analysis. Finally, the factor analysis method (FAM) is used to classify the six indicators into two categories: traffic efficiency and traffic safety, so as to comprehensively evaluate the different schemes. The results show that the difference in performance between the two schemes was not significant at low traffic volumes. At high traffic volumes, the turbo roundabout was better than the conventional roundabout in terms of emissions, safety and throughput efficiency. CO emissions from vehicles on conventional roundabout are generally higher than those on turbo roundabout, up to 53.62%. Therefore, the turbo roundabout is more appropriate for heavy traffic conditions.