Method For Improving Performance Research Articles

Analysis of performance improvement methods for offshore wind turbine blades affected by leading edge erosion

Leading edge erosion (LEE) poses greater challenges to the blade design of offshore wind turbines. This paper analyzes the influence of LEE on blade aerodynamic performance and wind turbine load based on high-power offshore wind turbines through the GH-Bladed computing platform. The study found that LEE severely weakens the blade aerodynamic performance, resulting in a lag in the wind turbine reaching its rated power. LEE expands the range of blade surface flow separation, leading to an increase in blade stall risk and a decrease in wind turbine load stability. The promotion of blade aerodynamic performance will cause an increase in blade force, which will strengthen the load level of both the blade and the wind turbine. The optimization of twist angle is an effective method to avoid the loss of power generation of wind turbines under LEE interference, but it is inevitable to cause a decrease in the load stability of wind turbines. Therefore, when the load safety margin of wind turbines is sufficient, adjusting the twist angle is an efficient technique to improve the blade aerodynamic performance and promote the stability of power output, which provides a novel solution for blade design of high-power offshore wind turbines.

Research on drilling performance and tool life improvement methods of titanium alloy ultra-high-speed drilling bits

Research on drilling performance and tool life improvement methods of titanium alloy ultra-high-speed drilling bits

Bionic-response surface combination optimization method for latent heat storage performance improvement

Improving the melting and solidification rate of phase change material is crucial for enhancing the charging or discharging power of a latent heat storage system. This research proposed a novel two-tube heat exchanger latent heat storage unit with longitudinal fins of horsetail stem based on the bionic structure of horsetail stem cross-section. Numerical modeling of transient melting of phase change material in horsetail stem fins by natural convection was established. The model’s accuracy was verified and compared with horsetail stem fins and conventional straight fins. Moreover, we optimized and designed the new fin structure based on the response surface method with minimum melting time as the objective function. The optimization results show that the optimized ponytail fins have a more uniform temperature distribution of the phase change material, significantly eliminating the influence of the heat transfer hysteresis zone, and reaching the steady state more quickly under the heat storage condition. Compared to straight fins, optimized horsetail stem fins reduced the heat storage area by only 3.80% and shortened the phase change material melting time by 44.30%. The solidification time was also reduced by 54.59%. This study provides a new idea for the structural design of phase change heat storage fins.

Investigation of membrane stress continuously adjustable fiber optic acoustic sensor based on inverse piezoelectric effect

In this paper, a fiber optic acoustic sensor with continuously adjustable membrane stress technology is proposed, in which the stress exerted on the membrane can be flexibly adjusted by employing the inverse piezoelectric effect of lead zirconate titanate (PZT) tubular pedestal. First, the response mechanism of stress on the membrane is investigated theoretically. Based on this principle, the effect of adjustable stress on the flat response region and sensitivity of a single mode-multimode-single mode (SMS) fiber optic acoustic sensor are studied experimentally. The experimental results reveal that the flat response region of the sensor extends from 250 Hz to 450 Hz following the continuous increase in the membrane stress by changing the positive direct current voltage applied on PZT from 0 V to 100 V; meanwhile, the sensitivity decreases gradually from 336.5 mV Pa−1 to 162.7 mV Pa−1. The results also verify that the average minimum detectable pressure of the sensor is maintained at 0.54 mPa Hz−1/2 with a fluctuation of 0.08 mPa Hz−1/2 during the tuning process of membrane stress, which provides a flexible method for performance and applicability improvement of membrane-based fiber optic acoustic sensors.

Examining Sustainable Construction Waste Management Methods for Potential Performance Improvement

Examining Sustainable Construction Waste Management Methods for Potential Performance Improvement

The Relationship between Leadership and Performance in Enhancing the Sustainability of Social Enterprises

As social enterprises are established for the purpose of solving local problems, the sustainability of social enterprises is also important for local development. In order to increase the sustainability of social enterprises, performance improvement is necessary, and research on finding leadership styles suitable for social enterprises continues to be an important method of performance improvement. However, despite considerable interest in social enterprises over the past few decades, no consistent conclusion has been reached about what leadership style is appropriate for social enterprises. The present study aimed to find a suitable leadership style for social enterprises within the major leadership styles recognized in commercial enterprises. This study investigated the impact of the three major leadership styles in commercial enterprises on satisfaction and performance in social enterprises. Based on prior research, transformational leadership, with its capacity to promote change and support the achievement of goals, was considered appropriate for social enterprises, and entrepreneurship was also considered as challenge is important for balancing economic and social purposes. Servant leadership also focused on the importance of providing support for employees on the basis that employees’ success is the success of social enterprises. In this study, in order to broadly understand the performance of different leadership styles, job satisfaction and leader satisfaction were considered at the individual level, and economic performance and social performance were considered at the firm level. To support the argument of this study, the researcher aimed to survey employees who perceive a leader as possessing leadership qualities in social enterprises. For this purpose, a survey on transaction leadership was conducted among employees who participated in a three-week training session related to social enterprises. And on the last day of training, three leadership and four outcome variables were surveyed. Analyzing data form 170 respondents in 52 social enterprises whose evaluation of their leader’s transactional leadership was higher than the average, the present study found that transformational leadership had a positive relationship with all four variables considered as leadership outcomes. And this study found evidence that entrepreneurship had a positive relationship with job and leader satisfactions, but the impact of entrepreneurship on economic and social performance was insignificant. However, servant leadership had a positive relationship with leader satisfaction and social performance, but the impact of servant leadership on job satisfaction and economic performance was insignificant. These results contribute to confirming that the emphasis on leadership styles in commercial enterprises can effectively operate in social enterprises as well, and that the effectiveness of leadership can vary depending on the desired outcomes.

Research on the Performance Improvement Method for Lithium-Ion Battery in High-Power Application Scenarios

With the development of technology, high-power lithium-ion batteries are increasingly moving towards high-speed discharge, long-term continuous output, instantaneous high-rate discharge, and miniaturization, and are being gradually developed towards the fields of electric tools, port machinery and robotics. Improving the power performance of batteries can be achieved from multiple dimensions, such as electrochemical systems and battery design. In order to improve the power performance of lithium-ion batteries, this paper proposes design methods from the perspective of electrochemical systems, which include increasing the high-rate discharge capacity and low impedance of the battery. This article also studies the preparation of high-power lithium-ion batteries. This article aims to improve the rate performance of batteries by studying high-performance cathode materials, excellent conductive networks, and high-performance electrolytes. This article successfully screened high-performance cathode materials by comparing the effects of different particle sizes of cathode materials on electrode conductivity and battery internal resistance. By comparing the effects of electrolyte additives under pulse cycling, high-quality electrolyte additive materials were selected. By comparing the effects of different types, contents, and ratios of conductive agents on electrode conductivity, battery internal resistance, high-quality conductive agents, and appropriate ratios were selected. Finally, a 10 Ah cylindrical high-power lithium-ion battery with a specific energy of 110 Wh/kg, pulse discharge specific power of 11.3 kW/kg, an AC internal resistance of ≤0.7 m Ω, a 10C full capacity discharge cycle of over 1700, a 30C full capacity discharge cycle of over 500, and a continuous discharge capacity of 10C–30C, and a pulse discharge capacity of over 100C was prepared.

Study of a vortex-induced vibration piezoelectric wind energy harvester based on the synergy of multi-degree-of-freedom technology and magnetic nonlinear technology

A novel multi-degree-of-freedom and magnetic piezoelectric wind energy harvester (MNPWEH) is proposed in this work to improve the working bandwidth and output power for the wind energy harvesting based on vortex-induced vibration. In the process of studying the presented collaborative strategy utilizing multi-degree-of-freedom and nonlinear force enhancement technologies, four response states of the harvester are observed and named as inter-well state, intra-well state, pulse state, and intermittent state. The key factors determining these four response states are firstly obtained through a series of numerical simulations and pre-experiments. Then, a thorough investigation into the influence of structural parameters on these four response states and the output performance of the system has been conducted. The findings from the experimental results indicate that greater tip mass of the outer beams results in higher output voltage generated by the same state, while the excitation magnet spacing can be adjusted for meeting different requirements in power and working bandwidth. In the optimal configurations, the fabricated prototype finally can obtain a maximum average power of 1.83 mW under the condition of v = 5 m/s and s1 = 15 mm, and maintain a wide working bandwidth of 2 m/s −6 m/s with an average output power above 0.66 mW when s1 = 25 mm, respectively. The main contribution of this study has been to confirm the effectiveness of the collaborative use of the multi-degree-of-freedom technology and magnetic nonlinear technology in piezoelectric wind energy collection based on vortex-induced vibration. It also provides a deeper new insight into the performance improvement method for vortex-induced vibration piezoelectric wind energy harvester.

Magnesium phosphate cement-based engineered cementitious composites with polyethylene fibers: Performance improvement and design method

This study aims to improve the performance of magnesium phosphate cement-based engineered cementitious composites (MPC-ECC) and establish a systematic design method. The MPC-ECC with ultra-high ductility was prepared with the polyethylene (PE) fibers. The effect of the magnesium oxide to potassium dihydrogen phosphate mass ratio (M/P), quartz sand particle size (Sd), water to solid mass ratio (W/S), sand to binder mass ratio (S/B), fly ash (FA) content and fiber volume fraction (Vf) on the micro-mechanical properties and macro-mechanical properties of MPC-ECC were explored. The macro-mechanical properties of MPC-ECC with different curing temperatures and curing ages were also tested. And the SEM test was carried out to analyze the morphology of the MPC-ECC. The results showed that the ultimate tensile strain of MPC-ECC with optimal proportion can reach 7.1%. Even curing at −10 °C for 7 days, the ultimate tensile strain can reach 5.6%, and the compressive strength can reach nearly 20 MPa. And the microstructure is characterized by a highly dense morphology. Additionally, with the increase of M/P, the compressive strength of MPC-ECC increases, but the ultimate tensile stress decreases. The MPC-ECC with the Sd of 150–180 mesh shows significant strain hardening performance, and its ultimate tensile strain can exceed 5%. The large W/S is helpful to improve strain hardening performance, especially when the S/B is 0.2. In addition, when the FA content is 30% or 40%, the strain hardening performance of MPC-ECC is significant. The quantitative association model between ultimate tensile strain and pseudo strain-hardening indices was established. According to the association model, the design method of MPC-ECC was established, based on which the MPC-ECC with desired ductility can be realized. Meanwhile, the PSHσ and PSHJ are recommended to reach 2.15 and 25.1, respectively, at the same time for the MPC-ECC with ultimate tensile strain of above 3%.

A sequential excitation and simplified ant colony optimization based global extreme seeking control method for performance improvement

To date, it is lacking of an effective global extreme seeking control (GESC) approach to improve transient responses. Motivated by this engineering problem, a novel and general method of global ESC is proposed theoretically and technically in three steps: the step of a simplified ant colony optimization (SACO) algorithm for the task of global extreme seeking, the step of a sequential excitation (SE) algorithm for the improvement of both transient and steady state responses, and the step of discrete to continuous control conversion to control the real world dynamical systems. Both numerical simulations and physical experiments have been conducted to verify the effectiveness of the proposed controller with SE-SACO on the overall performance improvement in terms of transient responses, steady state responses and global extreme seeking. In comparison with the cutting-edge methods such as IABC-SHTS, SSA, BA and GA-ACO, the settling time and oscillations due to the proposed method are reduced significantly when keeping the global extreme seeking ability. It alleviates the conflict of global extreme seeking and good transient responses of the dynamical systems, an unsolved issue in the literature.

Numerical study on smoke temperature and exhaust efficiency in electric cable tunnel

Cable tunnels are the lifeline of cities. Once a serious fire occurs on cables, the toxic smoke generated by cable combustion spreads and escapes, causing serious harm to the surrounding environment and personnel. The heat generated can also ignite nearby combustibles, causing casualties and property damage. Based on the above issues, using fluid dynamics methods, fire dynamic simulation was used to simulate cable tunnel fire scenarios under four variables: wind speed, fire source power, smoke outlet height, and smoke exhaust airflow. The temperature distribution law of the ceiling smoke layer inside the cable tunnel, smoke generation law, tunnel smoke exhaust efficiency, and other factors were clarified, revealing the impact mechanism of the above factors on tunnel fire smoke exhaust efficiency and smoke performance improvement methods. The research results indicate that the combination mode of exhaust air volume and ventilation air speed can effectively control tunnel fire smoke, providing a reference for the fire prevention design of cables in urban cable tunnels.

MSEConv: A Unified Warping Framework for Video Frame Interpolation

Within the context of video frame interpolation, complex motion modeling is the task of capturing, in a video sequence, where the moving objects are located in the interpolated frame, and how to maintain the temporal consistency of motion. Existing video frame interpolation methods typically assign either a fixed size of the motion kernel or a refined optical flow to model complex motions. However, they have the limitation of data redundancy and inaccuracy representation of motion. This paper introduces a unified warping framework, named multi-scale expandable deformable convolution (MSEConv), for simultaneously performing complex motion modeling and frame interpolation. In the proposed framework, a deep fully convolutional neural network with global attention is proposed to estimate multiple small-scale kernel weights with different expansion degrees and adaptive weight allocation for each pixel synthesis. Moreover, most of the kernel-based interpolation methods can be treated as the special case of the proposed MSEConv, thus, MSEConv can be easily transferred to other kernel-based frame interpolation methods for performance improvement. To further improve the robustness of motion occlusions, an operation of mask occlusion is introduced. As a consequence, our proposed MSEConv shows strong performance on par or even better than the state-of-the-art kernel-based frame interpolation works on public datasets. Our source code and visual comparable results are available at https://github.com/Pumpkin123709/MSEConv.

Study on cavitation performance improvement of high-power centrifugal pump impeller

High power centrifugal pump is frequently used in large project for water resources allocation. Cavitation phenomenon causes noise and vibration and affects the centrifugal pump unit stability. The impeller model was used an initial impeller to be developed, and the impeller geometry, the blade profile, blade inlet edge were optimized by design method based on numerical simulation technique to improve cavitation performances. The 3D model with the initial and optimized impeller were simulated to obtain cavitation characteristic. The results of optimization impeller are compared and verified by model test. The numerical simulation results show that the pressure distribution is distributed on the blade surface is uniform and the location of lowest pressure is reasonable. The test results show that the optimized design significantly increases the ratio of plant cavitation coefficient σp to incipient cavitation coefficient σi and critical cavitation coefficient σ1 of the impeller under normal operation conditions, the safety margin of cavitation is increased. It was confirmed from numerical simulation and model test results that the impeller blade optimization is a reasonable and effective method for cavitation performance improvement. The study results provides design reference for the cavitation performance improvement and safe operation of high power centrifugal pump.

Promising methods for improving the radio-frequency ion thruster performance

Improving the reliability and efficiency of available electric propulsion schemes is one of the priority areas of space technology development. In particular, this should be done for ensuring the guaranteed removal of spacecraft to a disposal orbit at the end of their active life, which, in turn, will slow down the growth in the number of space debris objects in the most exploited regions of near-Earth space. The paper considers ways to improve the power and mass efficiency of one of the modern electric propulsion types - a radio-frequency ion thruster with an inductive radio-frequency discharge. Using an engineering physico-mathematical model, computational studies were performed to optimize the shape of the radio-frequency ion thruster main components, namely the discharge chamber and the grids of ion-extraction system. The thrust of the thruster was used as the optimization criterion; it was determined from the calculated ion density distributions in the radio-frequency discharge plasma. Such an approach to refine the performance improvement methods has not previously been applied to radio-frequency ion thruster. The ion density distributions, as well as the thruster integral characteristics determined from them, such as the thrust, total ion current from the thruster, propellant utilization factor, ionization cost and a number of others, were calculated for two actual standard sizes of radio-frequency ion thruster with the beam diameters of 80 mm and 160 mm, which can be used to solve the problems listed above. Besides, for the defined optimal configurations of thruster with two standard sizes the calculations were made to assess the possibility for increasing the thruster integral characteristics by applying an additional magnetostatic field in the radio-frequency discharge region. The study revealed the possibility of noticeable performance improvement compared to the basic radio-frequency ion thruster design with hemispherical discharge chamber and flat grids of the ion-extraction system.

The performance improvement method of g-C3N4 based catalyst for hydrogen production from ammonia borane: A DFT investigation

In the study, based on the purpose of efficient catalytic AB for hydrogen production, the photochemical properties influence of metal(Ru, Ni) and nonmetal(B,P) elements doping on the g-C3N4 are studied systematacially. The design method of high performance bifunctional catalyst of photocatalysis and metal catalysis are provided. The results have proved that both non-metals B, P and metal Ru, Ni have an efficient regulatory effect on the band structure of g-C3N4, which make the band gap of the clean monolayer g-C3N4(001) decrease from 1.175 eV to 0.261eV(B-g-C3N4(001)) and 0.671eV(P-g-C3N4(001)), 0.164 eV(Ni-g-C3N4(001)) and 0.260 eV(Ru-g-C3N4(001)), respectively. B element have the better modification effect compared with the P element. The reduction of band gap is attributed to the electronic orbit modification effect of impurity element B, P, Ni, Ru in g-C3N4. Ru metal doped g-C3N4 is reduces the barrier of OH bond breakage of CH3OH(reduced from 4.551 eV to 1.530 eV), which is beneficial to the hydrogen-producing reaction of AB alcoholysis. The construction and design of a new bifunctional catalyst(photocatalysis and metal catalysis) RuNiB@g-C3N4 is an efficient route in catalyze AB for hydrogen production. The process of molecule NH3BH3, CH3OH and H2O adsorbed on the B-g-C3N4 are exothermic process, the adsorption energy are -1.562 eV, -1.392 eV and -1.443 eV, respectively. AB is preferentially adsorbed on the B-g-C3N4 catalyst, increasing the adsorption energy of CH3OH and H2O on B-g-C3N4-based catalysts is beneficial to the hydrogen production from AB. The study provides a theoretical method for the research on the technology of the coupling of metal catalysis/photocatalysis ammonia borane to produce hydrogen.

Structural gradient optimization of diffusion layer based on finite data mapping method for PEMFC performance improvement

Optimized design of the full structure is a key solution to improve the overall performance of proton exchange membrane fuel cells and advance their commercialization. This paper established a three-dimensional mathematical model of PEMFC, and obtained a series of simulation data collection under different structural parameters. On this basis, we derived the mapping relationship between the thickness of the diffusion layer and the output power using response surface analysis, and then obtained the optimal structural parameters by the BP neural network. The optimization provided a new type of gradient diffusion layer used in the PEMFC, i.e., a tapered diffusion layer. Compared with the fuel cell using a conventional diffusion layer under the same flow channel structure and operating conditions, the results show that the average power of the fuel cell using a gradient diffusion layer has been increased by 3.5 %. The overall heat transfer capacity increased by 10.3 %, and the oxygen utilization increased by 8.7 %. Finally, this paper analyzed the multi-physics field synergistic performance of PEMFCs with different diffusion layer structures, and found that the fuel cell with tapered diffusion layer has better synergistic performance in terms of temperature and concentration fields, and temperature and velocity fields.

Algorithm Optimization and Performance Improvement of Data Visualization Analysis Platform based on Artificial Intelligence

With the rapid development of artificial intelligence, data visualization analysis platforms have been widely applied in various fields. This study mainly explores the optimization and performance improvement of algorithms for data visualization analysis platforms based on artificial intelligence. Firstly, the definition of a data visualization analysis platform and the application of artificial intelligence in it were introduced, and the current problems and challenges were pointed out. Then, a discussion was conducted on algorithm optimization for various stages of research, including data preprocessing, data clustering, data classification, and optimization of data association analysis algorithms. Subsequently, the study proposed some performance improvement methods, including the application of parallel computing technology, distributed computing technology, data compression technology, and data indexing technology.

A novel morphological conversion strategy of carbon nitride by ammonia water to enhance the photocatalytic inactivation of Escherichia coli

Carbon nitride-based nanomaterials are widely used in photocatalytic degradation. However, the common type has limited performance, and the traditional functionalization procedure is fussy. Herein, a morphological conversion strategy based on ammonia water is proposed for the carbon nitride-based nanomaterials (C3N4) to improve the photocatalytic performance. Under the effect of ammonia water, C3N4 is capable of conversing into hollow tube (C3N4 HTs) and hollow cone (C3N4 HCs). Further assay results demonstrate that the transformed morphology can increase the specific surface area, particularly for C3N4 HCs, generating more exposed active sites. The conduction band (ECB) and valence band (EVB) of the C3N4 HCs are −1.05 (±0.005) V and 1.69 (±0.015) V, respectively, which are significantly higher than those of the common g-C3N4 and C3N4 HTs, suggesting stronger photocatalytic properties. Meanwhile, the produced reactive oxygen species (ROS) from the C3N4 HCs are polybasic, which the level order is •O2–＞•OH＞1O2. Subsequently, C3N4 HCs were employed to degrade Escherichia coli in the water. Exposing in xenon lamp, the generated free radicals and 1O2 from C3N4 HCs rapid oxidize and eliminate the Escherichia coli, and the purification rate reaches ∼ 100 % within 2 h. In contrast to other commonly used methods for photocatalytic degradation, this work focuses on material morphology conversion to propose a robust and highly efficient method for performance improvement. It has promising applications in water purification and ecological protection.

Extended State Observer-Based Predictive Current Control for Dual Three-Phase PMSM with High Dynamic Performance

Model predictive controllers are widely discussed in the field of dual three-phase permanent magnet synchronous motor control. However, conventional predictive current controllers usually suffer from parameter inaccuracies or model uncertainties, resulting in prediction errors and deterioration of control performance. Therefore, in this paper, an extended state observer-based (ESO) model predictive current controller is proposed to effectively improve the dynamic performance of the motor and its robustness to parameters or disturbances. Parameter inaccuracies or model uncertainties are considered to be lumped disturbances and expressed in the modified mathematical model of the motor. Then, with the designed observer estimating the external disturbances in real time, the prediction error is compensated and corrected periodically. Additionally, the parameter design method of the observer is presented to simplify the controller design. Finally, comparative experiments are implemented to sufficiently demonstrate the effectiveness of the proposed method for dynamic performance improvement as well as for parameter robustness. The results show that the proposed method takes only 17μs of computation time with a closed-loop bandwidth of 1839rad/s. In addition, the maximum d-axis following error of the proposed method is only 0.10A in the load dynamics experiments, which is a significant improvement compared to the 0.79A of the traditional proportional-integral controller.

On winding reconstruction method for six-phase motor with single-phase winding open-circuit faults

Single-phase winding fault in six-phase permanent magnet synchronous motor (PMSM) will cause problems with reduced torque performance. For this problem, this paper analyses the reasons for the increase of torque ripple under single-phase winding open-circuit fault condition taking an 18-slot/10-pole (18S10P) six-phase surface mounted permanent magnet synchronous motor (SPMSM) as an example. Then, a torque performance improvement method by redistributing healthy phase windings to reconstruct the stator magnetic field is proposed in this paper. The proposed method not only can significantly reduce torque ripple caused by winding open-circuit faults but also can maintain a high average torque value. Moreover, this method is suitable for lots of six-phase motors with different pole-slot combinations. At last, considering the significant impact of harmonic contents in stator magnetic field on torque performance, an optimization method for armature current is proposed, which can decrease the torque ripple further. The simulation results by finite element analysis (FEA) show that the proposed method has significant superiority in motor fault operation.