Speed Operation Research Articles

Numerical study of the self‐priming process of a prototype pump based on coupled calculations of circulatory system

AbstractTo understand the self‐priming characteristics of a self‐priming pump, a closed‐loop piping system that includes the self‐priming pump, valve, tank, and piping system is established. The acceleration–constant speed operation processes of the impeller are controlled through a user‐defined function that ensures that the computational model and startup conditions are consistent with the real situation. Based on numerical calculations of the self‐priming process with two different self‐priming heights, the gas–liquid distributions during the self‐priming startup process are obtained. The results show that the self‐priming startup process can be divided into three stages: rapid inhalation, oscillating exhaust, and accelerated exhaust. Under the two self‐priming heights, the time required for the rapid inhalation and accelerated exhaust stages is basically the same. Thus, the difference in self‐priming time is mainly concentrated in the oscillating exhaust stage. The rate at which the liquid level rises in the vertical pipe is not proportional to the self‐priming height, and the difference in the self‐priming time is not proportional to the change in the self‐priming height.

AI-Driven Global Sanctions Enhancement

This thesis examines the integration of Artificial Intelligence (AI) into global sanctions management, a field currently dominated by manual processes and semi-automated systems that are inefficient and error-prone. With the increasing complexity and volume of international financial transactions, traditional approaches to sanctions compliance are no longer adequate to meet the demands of dynamic global regulations and enforcement challenges. The primary aim of this research is to explore how AI can revolutionize sanctions management by enhancing accuracy, speed, and adaptability in compliance operations. Key findings reveal that AI can significantly reduce the reliance on human intervention, thereby decreasing operational costs and minimizing errors. AI-enhanced systems are shown to improve the consistency and reliability of compliance measures, effectively manage large volumes of data, and swiftly adapt to regulatory changes. The research highlights that integrating AI into sanctions management not only bolsters compliance efficiency but also strengthens the overall risk management framework of financial institutions. The significance of this research lies in its potential to guide financial institutions in implementing AI solutions that can transform their sanctions compliance frameworks. By providing a detailed roadmap for the adoption of AI, the study contributes to broader efforts to enhance global financial security and compliance, positioning AI as a pivotal technology in the evolution of global sanctions management.

Fast physical reservoir computing, achieved with nonlinear interfered spin waves

Reservoir computing is a promising approach to implementing high-performance artificial intelligence that can process input data at lower computational costs than conventional artificial neural networks. Although reservoir computing enables real-time processing of input time-series data on artificial intelligence mounted on terminal devices, few physical devices are capable of high-speed operation for real-time processing. In this study, we introduce spin wave interference with a stepped input method to reduce the operating time of the physical reservoir, and second-order nonlinear equation task and second-order nonlinear autoregressive mean averaging, which are well-known benchmark tasks, were carried out to evaluate the operating speed and prediction accuracy of said physical reservoir. The demonstrated reservoir device operates at the shortest operating time of 13 ms/5000-time steps, compared to other compact reservoir devices, even though its performance is higher than or comparable to such physical reservoirs. This study is a stepping stone toward realizing an artificial intelligence device capable of real-time processing on terminal devices.

Impact of initial conditions on the effectiveness of rolling dynamic compaction of granular soils

A finite element model (FEM) of rolling dynamic compaction (RDC) technology of a BH 1300 4 sided 8 tonne impact roller, developed previously by the authors, has shown to have reasonable agreement with that observed in the field. The use of this FEM is likely to provide high fidelity insights into the capability of the BH 1300 4 sided 8 tonne impact roller, namely in predicting the settlement and densification of an underlying granular material. A parametric study utilising this FEM with respect to initial density and shear strength parameters is undertaken to explore the relationship these properties have to the settlement and densification of a soil subject to RDC with a BH 1300 4 sided 8 tonne impact roller. The empirical relationships constructed within this study are validated against field trials from the literature of the roller improving sandy gravel fill at typical operating speeds of 10 km/h.

Highly efficient lead zirconate titanate ring modulator

Advanced photonic integrated circuits require large-scale integration of high-speed electro-optic (EO) functional components on a chip. Low power consumption and high operation speed are thus key metrics for almost all integrated EO devices. Here, we demonstrated a ring resonator modulator based on lead zirconate titanate (PZT) on a SiO2/Si substrate. The ridge waveguides were employed to keep a large spatial overlap between the optical field and the electric field within the PZT layer. The device exhibits a data rate of 56 Gbit/s and significant tuning efficiency, reaching up to 35.8 pm/V, corresponding to 1.17 V·cm. The demonstration of energy efficient and high-speed EO modulation paves the way for realizing dense PZT photonics integrated circuits.

P‐264: Fast‐Response FFS LC Device with Multi‐rubbing Angle for VR Applications

In this paper, we propose new fast response FFS LC devices with virtual walls by using alternating (or multi) rubbing directions, which can be generated by using photo‐alignment. These new devices can offer much‐enhanced response‐speed compared to the conventional FFS LC device. By choosing different types of “local” LC molecular arrangements or designs (easily achievable by using photo‐alignment), we may be able to alter the virtual wall pitch length, and hence also alter the response speed and transmission of these fast response LC devices. These new designs can provide a new and alternative approach to generating virtual walls by “locally” varying the rubbing angle using photo‐alignment. These devices are attractive for VR applications where high speed operation of liquid crystal devices is required.

Numerical study of rotor-stator interaction in variable speed reversible pump-turbine in turbine mode at low head

Abstract Pumped storage hydropower (PSH) offers the cost-effective storage of large quantities of energy with high efficiency. Reversible pump-turbines (RPT) are used in PSPs having large head variations and where variable speed operation can enhance its efficiency and grid stability. The RPT may experience higher fatigue and vibrations due to hydraulic instabilities caused by pressure fluctuations in the vaneless space between runner blades and guide vane interaction, known as rotor-stator interaction (RSI). Because of this instability, the local components of the powerhouse vibrate severely. Therefore, there is a need to study the pressure fluctuations caused by RSI in the variable speed RPTs. The present numerical study focuses on the pressure fluctuations due to RSI in turbine mode conditions having low available head. The present study used a reduced scale high-head variable speed RPT model, and the SST k-ω turbulence model was used to carry out numerical calculations. The analysis was performed at the best efficiency point and low head operating conditions having optimized rotational speed. The analysis showed that the main source of pressure fluctuations in the RPT at all operating conditions is the RSI, where the dominant frequency is BPF and its harmonics.

Study of axial hydraulic thrust and radial force characteristics of a variable speed pump-turbine unit

Abstract When the pump turbine does variable speed operation, it can improve the operation efficiency in the turbine mode, and it can improve the automatic frequency adjustment efficiency in the pump mode. However, the hydraulic thrust will also change when the speed changes, and the magnitude of the hydraulic thrust is crucial for the safe and stable operation of the unit. The work of this paper is to analyze the changes of the axial hydraulic force and radial force with the change of the speed by numerical simulation method. It is found that the fluctuation of axial hydraulic thrust can reach about 34 t at 398.57rpm speed, 37 t at 412.16rpm speed and 21 t at 428.6rpm speed. the fluctuation of radial force can reach about 13.78 t, 14.4 t and 12.4 t. The purpose of this paper is to use the simulation results to understand the hydraulic thrust characteristics and ensure the stability of the unit to select the appropriate speed range, provide the basis for stable operation of the unit under design conditions.

Vibration of Variable Speed Pump-Turbine in Turbine Operating Range: Simulation by CFD+FEM

Abstract Variable speed pumped-storage unit can operate efficiently and stably in wide range of power and head through the coordinated control of the rotational speed and guide vanes. The regulation in rotational speed brings about frequency and amplitude changes of pressure pulsations, which further influence the avoidance margin of vibration and the dynamic response of the runner. The vibration characteristics of the variable-speed pump-turbine need to be studied when it runs in the wider operating region. Selecting an actual pumped-storage unit as the subject and using the CFD+FEM coupled simulation method as a tool, we conducted three-dimensional pump-turbine vibration simulations and analyse the flow patterns, pressure pulsations, and runner vibration characteristics of several typical operating points in turbine mode. The study focused on the variation laws of pressure pulsations and dynamic stresses when rotational speed is regulated. Comparison with the results for the constant speed unit under the corresponding working conditions was conducted. It is shown that the variable speed operation can effectively avoid the severe vibration conditions that the constant speed unit encounters; the amplitudes of pressure pulsations and dynamic stresses of the runner are small at low rotational speed; in the condition of high speed, low head, and small load, the vibration is the most obvious. This study can provide a reference for the design and operation of variable speed pump-turbine.

Experimental study on draft tube of a model kaplan turbine

Abstract To obtain the flow characteristics inside the draft tube of the model Kaplan turbine, a model test method was developed and carried out in this paper. The method includes introducing the model test system, test method, and parameters of model Kaplan turbine. Subsequently, experiments are conducted under different operating conditions and the results are analyzed. The result shows that, for the same blade angle and unit speed, operating conditions with larger guide vane openings (GVO) generally have higher axial velocities and lower tangential velocities than those with smaller GVO. In addition, particularly at higher flow velocities, a low velocity or backflow zone can occur in the center of the draft tube. Vortex rope is found to have a significant impact on the turbulence intensity in the mid-section of the draft tube, resulting in an unstable flow state. Also, under higher unit speed operating conditions, the turbulence intensity in the middle of the measurement area is greater and has a larger sphere of influence. Finally, the tangential pulsation intensity at the same measuring point under the same operating conditions is larger than the axial pulsation intensity, showing that vortex ropes have a more significant influence in the tangential direction.

Транспортная энергоэффективность и экономические принципы организации морского судоходства

Modern problems of ensuring energy efficiency and carbon intensity of marine vessels are considered, taking into account the achievement of profitability of flights. Since January 2023, such issues have been particularly acute for all maritime convention vessels engaged in international transport, taking into account the introduction of amendments to annex VI of the International Convention for the Prevention of Pollution from Ships (MARPOL), developed within the framework of the IMO short-term strategy until 2030 to reduce emissions greenhouse gases from ships. The composition of the world merchant fleet by ship types and deadweight was analyzed, the work of the tram freight market and the features of achieving optimal economic operational speed of the vessel were evaluated, taking into account operational and technical conventional restrictions on carbon intensity. The transport work of the universal vessel Singularity over the past three years has been analyzed, taking into account changes in operational speed and the level of freight rates. An adequate mathematical model has been proposed for assigning an optimal average operating speed to a ship according to a carbon intensity rating. The proposed methodological materials can be used by shipping companies in the commercial and technical operation of the fleet by assigning an operational speed in preparation for the voyage and when carrying out corrective energy efficiency measures to achieve an acceptable level of carbon intensity ratings for marine vessels.

Implementation of AI-Based Robotic Self Navigation System

Abstract: Artificial intelligence (AI) has revolutionized modern weapon systems, offering increased speed, precision, and capability in military operations. However, the use of AI-based weapon systems increases significant moral legitimate, and operational challenges that need to be satisfied in the development of AI-based weapon systems. Autonomous operation is a key feature of A-I-based weapon systems, posing important questions regarding accountability and the risk of unpremeditated outcomes. This automatic weapon is a remote weapon that is automatically aimed and fired at targets that are detected by sensors. The first of its kind to have an integrated system that includes stewardship, pursuit, and firing. The function of automatically selecting, attacking targets could be available on many platforms such as battle tanks, fighter jets, or ships. human out-of-the-the-scheme system, once activated, can select automatically and engage targets without further interference by a human operator. For example “loitering” weapons that once launched, detect interference and attack their conscious targets over a specified area without any further human interference or weapon systems that autonomously use electronic “cramming ” to confuse communications.

Analysis and Modeling of the System Boundaries of a High-Speed Direct-Yarn-Placement System for In Situ Impregnation of Carbon Fibre Heavy Tows as Textile Reinforcements for Concrete Parts

This study investigates a novel approach in modeling the system limits of a braked, high-speed yarn-laying process with in situ impregnation. Special attention is paid to the investigation of the yarn spool overrun after the robot has come to a standstill. This phenomenon occurs at low yarn tensions in combination with high traversing speed and/or acceleration. The modeling of the yarn spool overrun is carried out using physical equations, taking into account the travel speed, acceleration of the robot, and braking force of the spool brake. Previous research has confirmed various operating points of the yarn-laying process, but a comprehensive and complete analysis of the system limits at different operating points and speeds up to 2 m/s is missing. The result of the study is a novel model that describes the system boundaries of the direct-yarn-placement. Furthermore, models for robot braking time, carbon spool diameter, and spool mass are developed. The proposed models have an R2 > 0.9674. Regarding the system stability boundaries, the calculations reveal that, as acceleration rises, the minimum tension requirement also increases. The same trend is found for system velocity. At a=12.5%, a minimum tension of 16 N suffices, compared to 23 N and 32 N at a=25% and 50%, respectively. The impact on tension of quadrupling the speed outweighs that of acceleration, with tension increasing by factors of up to 22.5 and 2, respectively.

Rapid ultrasensitive and specific BNP biosensor with LED readout.

Biosensing for diagnostics has risen rapidly in popularity over the past decades. With the discovery of new nanomaterials and morphologies, sensitivity is being constantly improved enough for reliable detection of trace biomarkers in human samples, like serum or sweat. This precision has enabled detailed research on the efficacy of biosensors. However, current biosensors suffer from reduced speed of operation. To make better use of this sensitivity, the development of a conductometric biosensor with in-situ use of an Laser Emitting Device (LED) display can provide rapid determination of sample results, steadily pushing biosensors toward more clinical, point-of-care (POC) applications. In this research, a simple LED was used for facile optical determination and visual output of an ultrasensitive bio-signal amplification circuit was made to interface with a B-type Natriuretic Peptide (BNP) biosensor. Tuning circuit gain enables an elegant method for adjustable separation of concentrations into 3 discrete categories: sub-threshold, analog, and saturation regions. These regions corresponded to 0 < [C] < 500pg/mL (25, 100, 250pg/mL, LED off), 500 < [C] < 1000pg/mL (LED varying intensity), and 1000pg/mL < [C] (LED full intensity). System efficacy was tested using human blood serum samples from University of Pittsburgh Medical Center patients, which were able to be accurately detected and sorted for rapid low cost and power. determination without need for complex digital elements. Additional specificity testing suggests insignificant impact of non-target biomarkers.

A Geth-based real-time detection system for sandwich attacks in Ethereum

With the rapid development of the Ethereum ecosystem and the increasing applications of decentralized finance (DeFi), the security research of smart contracts and blockchain transactions has attracted more and more attention. In particular, front-running attacks on the Ethereum platform have become a major security concern. These attack strategies exploit the transparency and certainty of the blockchain, enabling attackers to gain unfair economic benefits by manipulating the transaction order. This study proposes a sandwich attack detection system integrated into the go-Ethereum client (Geth). This system, by analyzing transaction data streams, effectively detects and defends against front-running and sandwich attacks. It achieves real-time analysis of transactions within blocks, quickly and effectively identifying abnormal patterns and potential attack behaviors. The system has been optimized for performance, with an average processing time of 0.442 s per block and an accuracy rate of 83%. Response time for real-time detection new blocks is within 5 s, with the majority occurring between 1 and 2 s, which is considered acceptable. Research findings indicate that as a part of the go-Ethereum client, this detection system helps enhance the security of the Ethereum blockchain, contributing to the protection of DeFi users’ private funds and the safety of smart contracts. The primary contribution of this study lies in offering an efficient blockchain transaction monitoring system, capable of accurately detecting sandwich attack transactions within blocks while maintaining normal operation speeds as a full node.

Nanoscale Investigation of the Effect of Annealing Temperature on the Polarization Switching Dynamics of Hf0.5Zr0.5O2 Thin Films

AbstractRecently, HfO2‐based ferroelectric thin films have attracted widespread interest in developing next‐generation nonvolatile memories. To form a metastable ferroelectric orthorhombic phase in HfO2, a post‐annealing process is typically necessary. However, the microscopic mechanism underlying the effect of annealing temperature on ferroelectric domain nucleation and growth is still obscure, despite its importance in optimizing the operation speed of HfO2‐based devices. In this study, the ferroelectric properties and polarization switching of Hf0.5Zr0.5O2 thin films annealed at different temperatures (550–700 °C) are systematically investigated. Evidently, the crystal structure, remnant polarization, and dielectric constant monotonically change with annealing temperature. However, microscopic piezoresponse force microscopy images as well as macroscopic switching current measurements reveal non‐monotonic changes in the polarization switching speed with annealing temperature. This intriguing behavior is ascribed to the difference in the ferroelectric‐domain nucleation process induced by the amount of oxygen vacancies in the Hf0.5Zr0.5O2 thin films annealed at different temperatures. This work demonstrates that controlling the defect concentration of ferroelectric HfO2 by tuning the post‐annealing process is critical for optimizing device performance, particularly polarization switching speed.

Изотермическое прессование в конической матрице релаксирующего материала

The relations for calculating the deformation mode and force conditions of isothermal extrusion of blanks made of high-strength metallic alloys are proposed. Under isothermal deformation, the material is hardened and softened, which is associated with the manifestation of the viscous properties of the material (creep). In this regard, the state of viscoplasticity is taken on. The deformation state is accompanied by stress relaxation, which is greater the lower the speed (longer duration) of the operation. Based on the mechanics of deformation, the dependence of moulding conditions (deformation, force, damage to the work material) is expressed by analytical relations. The power balance of activity of forces results in a pressure estimation for isothermal exposure. In this case, a discontinuous field of path velocities is used, which consists of a block of deformations and rigid blocks. The blocks are separated by slip surfaces. Deformations occur in the deformation block and on slip surfaces. Since pressing leads to the occurrence of micro-damages, the damage rate of the coating material was estimated. In this case, the criteria of fracture kinetics are used: energy and deformation equations. The damage rate of the material depends on the speed and degree of deformation, or solely on the degree of deformation. For a number of materials, reducing the speed helps to reduce damage and, consequently, the possibility of increasing the degree of shaping of the primary blank. The relations for stiffness analysis of the stress pattern are given, on which the damage also depends. Calculations of the pressure and damage of the material under compaction for blanks made of titanium and high-strength aluminum alloys have been performed. It is shown that at low operation speeds on the appropriate hydraulic forging equipment, the exposure pressure decreases significantly. The aluminum alloy damaging is also reduced, and for titanium it depends only on the degree of forming.

Analysis, Modeling, and Simulation Solution of Induced-Draft Fan Rotor with Excessive Vibration: A Case Study

In the modern industry, computer modeling and simulation tools have become fundamental to estimating the behavior of rotodynamic systems. These computational tools allow analyzing possible modifications as well as alternative solutions to changes in design, with the aim of improving performance. Nowadays, rotodynamic systems, present in various industrial applications, require greater efficiency and reliability. Although there are deep learning methodologies for monitoring and diagnosing failures which improve these standards, the main challenge is the lack of databases for learning, a problem that can be addressed through experimental monitoring and computer analysis. This work analyzes the vibrations of two induced-draft fans with excess vibration in a thermoelectric plant in Mexico. A vibration analysis was carried out through the instrumentation and monitoring of accelerometers located at crucial points in the fans. The results of this experimental analysis were validated by computer simulation based on FEM. The results show that the operating speed of the induced-draft fans is very close to their natural frequency, causing considerable stress and potential failures due to excessive vibration. Finally, this work presents a practical solution to modify the natural frequency of induced-draft fans, so that they can function correctly at the required operating speed, thus mitigating excessive vibration issues.

Design and Implementation of a Hybrid-Driven Soft Robot

Currently, soft robots alone cannot obtain the same operating speed as rigid robots, while rigid robots are not safe enough for human-robot interaction. To address this problem, this paper describes a hybrid robot system that combines both rigid and flexible systems for unknown domain exploration. The system consists of a four-wheeled robot chassis and a cylindrical pneumatic soft actuator, and finally, a computer is used to coordinate and control both. The hardware of the robot system is designed, a bending motion model is proposed, and SOFA framework is used to carry out finite element simulation (FEM) to verify the reasonableness of the design; linear motion speeds of up to 0.5 m/s, higher than the existing soft robots investigated, were verified experimentally separately after carrying the new module, and steering ability was retained; and the robot carrying the navigation module is verified to have a certain map building and localization function through the construction of the simultaneous localization and mapping (SLAM) experimental platform. The hybrid robot introduced in this paper can move quickly on flat terrain and can use its soft part to avoid wear and tear.

Sensorless fuzzy-sliding mode control of five phases permanent magnet synchronous motor using MRAS: in three different operating modes

This paper presents a comprehensive study on sensorless control techniques for five-phase permanent magnet synchronous motors (5P-PMSMs). To optimize the speed control performance of (5P-PMSM), which has more advantages than its counterpart three-phase PMSM system, we utilized a combination of fuzzy logic and sliding mode control techniques to optimize the proposed sliding mode control. Additionally, the Model Reference Adaptive System (MRAS) is employed to estimate the speed and rotor position of the 5P-PMSM to enhance the robustness and adaptability of the control system. The modelling of the machine, detailed with a robust nonlinear strategy based on the sliding control, is introduced to track the system until the desired sliding surface is achieved first. To guarantee that the tracking errors converge, the sliding mode control has a chatter due to the discontinuous term. To mitigate the drawback, the proposed control is designed by combining SMC with fuzzy logic, enhancing the performance in a steady state. Examining the control performance of the integrated control fuzzy-SMC with MRAS in different operating modes, including three tests in reversal speed operation, open phase fault mode, and the low-speed operating mode under load torque. The main aim is to assess and analyze the robustness and performance of the proposed control strategy. The stability of the overall control system is examined using the Lyapunov theorem and Popov’s theory analysis of MRAS observer stability. The simulation results of the suggested control displayed by MATLAB-Simulink illustrate the effectiveness and adaptability of the sensorless control scheme across different operating conditions, offering promising prospects for practical implementation in industrial applications.