Simulation Performance Analysis Research Articles

Experimental measurement and molecular dynamics simulation analysis of thermal aging performance in composite solid propellants

As a complex mixed system, the aging mechanism of high-energy composite materials involves the aging of each component itself, interactions between components, and transformation of microstructural and thermodynamic properties. The study of a single component or performance parameter has great limitations for elaborating the cognitive complexity of aging processes, making it difficult to reveal the underlying principles of physicochemical property transformation. Thus, it can only be applied as an empirical summary. In view of this, this study comprehensively utilized numerical analysis and experimental detection to explore the evolution of micromolecular conformation and changes in macro aging performance from four aspects of composite systems, including binder aging, plasticizer migration, bond interface debonding, and mechanical property transformation. There was good consistency observed between molecular simulation and thermal aging experiments, indicating that there was basically no post curing process for HTPB propellants using TDI as the curing agent. In the early stage of aging, scission chain was the main process and, in the later stage of aging, oxidation crosslinking the main process. Oxidative crosslinking increased the mean square radius of gyration and glass transition temperature of the binder system, reduced the peak value of radial distribution function, and revealed the reason for the change of propellant hardness and CC and CO double bond content. However, chain degradation increased the number of polar groups, enhanced intermolecular polarity, reduced the solubility parameter, and increased the free volume fraction of the mixed system and the dioctyl sebacate diffusion coefficient. This resulted in an increase in the tangent value of the HTPB propellant loss angle from 0.43 to 0.44° and a decrease in the glass transition temperature from 203.3 to 202.0 K. The binding energy at the interfaces of AP/HTPB and Al/HTPB increased first and then decreased, which was consistent with SEM images of bonding interfaces. The joint effect of binding energy and mechanical properties of the binder system promoted the transformation of the stress-strain curve of aging propellant.

Numerical Simulation Analysis of the Bending Performance of T-Beams Strengthened with Ultra-High-Performance Concrete Based on the CDP Model

In bridge reinforcement projects, damaged T-beams are the most common objects for reinforcement, yet the interface bonding and bending performance of UHPC reinforcement on T-beams have hardly been studied. To ensure the reliability and stability of UHPC-strengthened T-beams in practical applications, this study introduced a post-installed rebar bonding technique to efficiently connect T-beams with UHPC layers. Initially, using ABAQUS software [2020 version] for finite element simulation, this study investigated the effects of various post-installed rebar parameters (horizontal spacing, yield strength, diameter, and matrix concrete strength) on the shear performance of the UHPC and RC interface, obtaining the optimal connection parameters. Subsequently, by comparing shear formulas in domestic and international standards, a new UHPC-RC steel bar interface shear strength theoretical formula with 93.6% accuracy was derived. Finally, finite element simulations analyzed the impact of different post-installed reinforcing bar layout forms and longitudinal spacing, as well as UHPC-strengthened location and layer thickness, on the bending performance of damaged T-beams. The results showed a good match between simulation outcomes and experimental results, applicable for further reinforcement analysis of T-beams. When the horizontal spacing of post-installed rebars is 12d, with diameters ranging from 10 mm to 14 mm, their anchoring capability is efficiently utilized. A square form of a post-installed rebar with a longitudinal spacing of 300 mm effectively improves the ultimate bending load capacity of the strengthened beam. The simulation analysis and theoretical results help in the design and application of post-installed steel connections and UHPC-strengthened structures in UHPC-strengthened reinforced concrete T-beam structures.

Potential Regenerative Impact of Implementation of Cultural Vernacular Elements (Rowshan) in Jeddah, Saudi Arabia

The present study aims to explore rowshans as essential vernacular architectural elements in designing houses in very hot-dry climates such as Jeddah, Saudi Arabia, to determine their most significant effects on air movement, ventilation, and mitigating cooling loads. A comprehensive combination of building performance simulation and computational fluid dynamics (CFD) analysis was used to model a room with six different sizes of rectangular openings and quantify rowshans’ potential as passive elements in providing occupants with comfort and reducing energy use. Analysis of the passive element revealed the thermal performance and natural ventilation in single-family homes for the Jeddah climate, created by outdoor and indoor temperature, airspeed, and pressure differences in the room model, were improved, lowering sensation temperature for inhabitants’ comfort. The results highlight the beneficial effects of rowshans in lowering a house’s temperature during the daytime: from November to April, at noon, indoor air temperature (IAT) could reach a 15% to 22% reduction in the north orientation. The findings also show that rowshans with 5 × 5 cm opening grids can keep the air volume flow rate within an acceptable range and keep the room in the comfort zone range for 42.3% of hours annually, equal to 3704 h. An implication of these results is the possibility of establishing housing design criteria that can enhance efficiency and thermal comfort conditions, lower the cost of operations, provide occupants with satisfaction, and reduce emissions to regenerate the environment, leading to affordability and sustainability in the Jeddah region.

Seeking a quantum advantage with trapped-ion quantum simulations of condensed-phase chemical dynamics.

Simulating the quantum dynamics of molecules in the condensed phase represents a longstanding challenge in chemistry. Trapped-ion quantum systems may serve as a platform for the analog-quantum simulation of chemical dynamics that is beyond the reach of current classical-digital simulation. To identify a 'quantum advantage' for these simulations, performance analysis of both analog-quantum simulation on noisy hardware and classical-digital algorithms is needed. In this Review, we make a comparison between a noisy analog trapped-ion simulator and a few choice classical-digital methods on simulating the dynamics of a model molecular Hamiltonian with linear vibronic coupling. We describe several simple Hamiltonians that are commonly used to model molecular systems, which can be simulated with existing or emerging trapped-ion hardware. These Hamiltonians may serve as stepping stones towards the use of trapped-ion simulators for systems beyond the reach of classical-digital methods. Finally, we identify dynamical regimes in which classical-digital simulations seem to have the weakest performance with respect to analog-quantum simulations. These regimes may provide the lowest hanging fruit to make the most of potential quantum advantages.

Research on Hybrid Relay Protocol Design and Cross-Layer Performance Based on NOMA

Wireless and power line communication hybrid relay technology can realize complementary advantages and comprehensively improve the communication coverage and performance of power Internet of Things. In order to study the mechanism of the physical layer and Media Access Control (MAC) layer algorithm that affects the performance of hybrid relay systems, the cross-layer performance modeling, optimization, and simulation analysis are carried out for the non-orthogonal multiple access (NOMA) technology. Firstly, a two-hop NOMA media access control protocol is designed based on the CSMA algorithm. Considering the effects of non-ideal channel transmission at the physical layer and competitive access at the MAC layer on the system performance, a cross-layer performance analysis model of hybrid wireless and power line communication relay system under NOMA is established. Finally, a cross-layer optimization model based on multi-objective programming is established for the hybrid relay system. By analyzing the relationship between transmitting power and performance index, the joint optimization of transmitting power and power distribution factor between users is realized. Simulation results verify the validity and reliability of the proposed cross-layer model. The results show that the hybrid relay algorithm combined with NOMA and CSMA can effectively improve the performance of the system throughput, packet loss probability, and delay.

Simulation Analysis of Frog-Inspired Take-Off Performance Based on Different Structural Models.

The frog-inspired jumping robot is an interesting topic in the field of biomechanics and bionics. However, due to the frog's explosive movement and large range of joint motion, it is very difficult to make their structure completely bionic. To obtain the optimal jumping motion model, the musculoskeletal structure, jumping movement mechanism, and characteristics of frogs are first systematically analyzed, and the corresponding structural and kinematic parameters are obtained. Based on biological characteristics, a model of the articular bone structure is created, which can fully describe the features of frog movement. According to the various factors affecting the frog's jumping movement, mass and constraints are added, and the complex biological joint structure is simplified into four different jumping structure models. The jumping ground reaction force, velocity, and displacement of the center of mass, joint torque, and other motion information of these four models are obtained through ADAMS simulation to reveal the jumping movement mechanism and the influencing factors of frogs. Finally, various motion features are analyzed and compared to determine the optimal structural model of the comprehensive index, which provides a theoretical basis for the design of the frog-inspired jumping robot.

Making Early and Accurate Deep Learning Predictions to Help Disadvantaged Individuals in Medical Crowdfunding

Medical crowdfunding is a popular channel for people seeking financial assistance to cover their medical expenses, allowing them to collect donations from a large number of donors. However, a mismatch between the supply and demand of donations creates large heterogeneity in the fundraising outcomes across medical crowdfunding campaigns, and such uncertainty can impede the timely planning of treatment for patients. Providing early and accurate forecasts for medical crowdfunding performance can better inform fundraisers and assist them in optimizing timely interventions to improve fundraising outcomes. In this study, we propose a new approach that effectively combines time-varying features and time-invariant features in a deep learning model, to provide dynamic predictions of fundraising outcomes. When compared with a comprehensive set of baseline models, our model consistently demonstrates higher predictive accuracy while requiring a shorter observation window of data, thus achieving both accurate and early prediction objectives. We further conduct a temporal clustering analysis to analyze the heterogeneous patterns in how the time-varying features relate to fundraising outcomes. In addition, we perform simulation analyses to demonstrate that interventions from fundraisers can significantly improve the fundraising performance of disadvantaged cases that are predicted to receive the lowest donation amounts, particularly when the interventions are implemented early. These findings show that our deep learning prediction model and the actionable insights can provide timely feedback to fundraisers and promote equal access to resources for all. Our proposed approach is applicable to various contexts, enabling effective processing of diverse sources of data and facilitating early interventions.

Performance analysis of vehicle magnetorheological semi-active air suspension based on S-QFSMC control

The performance of the suspension is a crucial criterion for evaluating both vehicle handling and passenger comfort. To enhance suspension performance, this study proposes the design of a Quantum Genetic Fuzzy Sliding Mode Controller (S-QFSMC) based on the Smith predictor estimator, building upon the foundation of the vehicle magneto-rheological semi-active air suspension. According to the physical model of the vehicle suspension, a mechanical model of a quarter-vehicle magneto-rheological semi-active air suspension with time delay is established. On this basis, a conventional sliding mode controller is designed, and quantum genetic algorithm and fuzzy control principles are employed to optimize the chattering issue associated with sliding mode control. The Smith predictor estimator is utilized to effectively compensate for the time delay in the suspension system. Subsequently, a simulation analysis of the vehicle suspension performance is conducted. The results indicate that, compared to passive suspension control, both the QFSMC controller and the S-QFSMC controller improve the suspension performance, with the S-QFSMC controller exhibiting superior comprehensive improvement. This validates the effectiveness of the designed controllers.

Analytical Solution for Electromagnetic Performance Analysis of Permanent Magnet Synchronous Motor with a Parallel Magnetized Cylindrical Permanent Magnet

High-speed direct-drive permanent magnet synchronous motors (PMSMs), supported by elastic foil gas bearings, have broad applications, such as in microcompressors. However, some problems remain to be solved for the electrical performance analysis of PMSMs. For example, there is presently no related analytical model that can be used in rotor dynamics expression for this type of PMSM. This study aimed to establish theoretical models for electromagnetic force density and torque. The process involved both theoretical and experimental research. The analytic models of air gap magnetic density, electromagnetic force density, and electromagnetic performance were established for a PMSM with a parallel magnetized cylindrical permanent magnet. The analytic calculation was conducted, and the results of the analytic model were obtained. The analytical model of the electromagnetic torque and force can be applied in theoretical research on rotor dynamics. The model provides a theoretical basis and method for studying the influence of the electromagnetic load on rotor dynamics. A finite element simulation analysis of the electrical performance of the PMSM was carried out. An electrical performance experiment was conducted. The deviation between the experimental result and the theoretical value was less than 4%. This result indicated that the analytic models could be used in a dynamics analysis of compressors that are directly driven by a PMSM for application in engineering and industrial contexts.

Optimized improvement of double-stage solar AES saline wastewater treatment system based on performance simulation and exergy analysis

Being an innovative, clean and high-efficiency double-stage solar air evaporating separation (AES) saline wastewater treatment system, it enables the full recovery of clean water and salt from saline wastewater. Nevertheless, there are still possibilities for optimized improvement in various aspects. Therefore, in this work, a well-established and accurately system simulation model is constructed, comprehensive performance is intensively analyzed, and different optimization and improvement methods are designed. Results demonstrate that among three potential improvements, “Improvement of three-stage switching operation” brings little effect, while “Improvement of distribution relationship” can effectively improve system adaptability to weather, particularly under overcast weather conditions. Moreover, “Improvement of regenerator” improves overall performance (gained output ratio (GOR), evaporation efficiency (EE) and overall system efficiency (ηsys), which are 20.11 %, 11.01 %, and 8.55 % higher than original system, respectively). Furthermore, the exergy analysis concludes that simultaneous implementation of “Improved distribution relations” and “Improved regenerators” is preferable. This improvement enhances system weather resilience and wastewater recycling capabilities in one fell swoop. This improved system can achieve an average GOR, ηsys and system exergy efficiency (ηex) of 2.588, 63.92 % and 2.849 %, respectively, throughout total summer months. Consequently, the best system improvement method is combining “Improvement of distribution relationship” with “Improvement of regenerator”.

Simulation analysis and experimental testing of the grading performance of small potato grading device

AbstractExisting potato grading device has a complex structure and a large volume, which is not suitable for small‐scale potato farmers. However, traditional manual grading methods not only have low efficiency but also high labor costs. This article developed a small movable rotating plate (MRP)‐type potato grading device, and the influences of three factors (the height of the horizontal slide, the tilt angle of the inclined slide, and the chain speed) on the grading efficiency and accuracy were investigated using the discrete element method and virtual orthogonal experiments. It was found that the horizontal slide height of 185 mm, the inclined slide tilt angle of 3.5°, and the chain speed of 0.9 m/s yielded the optimal grading efficiency (13.84 t/h) and grading accuracy (94.11%). Finally, the potato grading process was tested and validated through indoor tests, and the optimal grading accuracy was 91.04%. The grading accuracy deviation between the test and simulation results was less than 8%.Practical ApplicationCurrently, most commercial potato grading machines are designed for large‐scale farms, which are not suitable for developing countries. The potato grading device designed in this article can not only be used independently by small‐scale farms, but also be integrated with potato combine harvesters to achieve potato harvest and grading joint operations. This grading device has a simple structure, small footprint (1700 × 1200 × 840 mm3), and a very low cost ($600). With a high grading efficiency and accuracy, it can significantly improve the grading productivity of small and medium‐sized potato farmers in developing countries, reduce the production costs, and save labors.

Fatigue Performance Analysis of an Underwater Vehicle Rudder Mechanism Considering Arctic Low Temperatures

For underwater vehicles navigating in Arctic Sea ice-covered waters, fatigue damage is a crucial issue. Many scholars have conducted low-temperature fatigue analysis on low-temperature materials and substrate platforms for ships, and the results show that low temperature is beneficial for improving the mechanical properties of materials. However, they have mainly focused on low-temperature performance experiments and simulation analysis of standard components of materials, and there are very few fatigue life experimental studies on underwater vehicle mechanical structures. This paper conducts experimental investigations on a scaled model of an underwater vehicle rudder mechanism in a polar environment laboratory. Using a comparative analysis method involving simulations and experiments, the low-temperature fatigue test data of the scaled underwater vehicle rudder mechanism are analyzed, and the quantified analysis between fatigue and different low-temperature loading cycles, as well as the influence of icing on the fatigue life, is explored. It is indicated that the Arctic environment can decrease the fatigue life of the underwater vehicle rudder mechanism by deteriorating its material properties. The paper builds the foundation for the fatigue life of an underwater vehicle rudder mechanism in Arctic low-temperature environments.

Performance simulation analysis of a novel dual-piston two-stage carbon dioxide linear compressor

In this study, an innovative two-stage linear CO2 compressor with dual piston is proposed and its simulation model is developed. The dynamic characteristics of the two-stage dual-piston compressor are comprehensively analyzed. The simulation results indicate that the dual-piston configuration leads to gas forces oscillating around the zero axis, resulting in a reduction in the mean gas force, allowing for the replacement of the resonance spring with gas springs and magnetic springs. The dynamic performance of the two-stage linear compressor is compared with that of a single-stage linear compressor. The moving center offset of the dual-piston two-stage compressor is reduced by approximately 90 %. The gas equivalent stiffness and the equivalent damping at the TDC (Top Dead Center) get lower than the single-stage one by 25.7 % and 11.6 % as the pressure ratio is set at 2.5. The leakage during the compression process gets lower by more than 20%. The dual-piston compressor demonstrates excellent capacity and modulation capabilities, with a theoretical increase in cooling capacity of over 300 W when the stroke is increased from 6 mm to 8 mm.

Simulated Performance Analysis of a Hybrid Water-Cooled Photovoltaic/Parabolic Dish Concentrator Coupled with Conical Cavity Receiver

The present research discloses a novel hybrid water-cooled Photovoltaic/Parabolic Dish Concentrator coupled with conical cavity receiver and spectral beam splitter (PV/PDC-CCR-BSF). In effect, a compact co-generating solar-concentrating PV system involving a subsequent optical interface has been fully developed and numerically tested. The optical performance of the proposed hybrid solar-concentrating system was modeled and assessed using the RT 3D-4R method while the thermal yield of the system was examined using the Finite Element Method. In addition to that, different configurations of serpentine-shape embedded water-cooling pipes (rectangle, semicircle, semi-ellipse and triangle) have been tested and optimized for maximum heat collection and minimum operating cell temperature. The performance of all the tested serpentine-shape embedded water-cooling pipes was evaluated with respect to conventional serpentine-shape water-cooling pipes. The outcomes indicated that the triangular cross-section outperforms other shapes in terms of heat dissipation capabilities, with about −446 W and maximum useful thermal power in the medium of the heat transfer fluid of 11.834 kW.

A novel computational fractional modeling approach for the global dynamics and optimal control strategies in mitigating Marburg infection

<abstract><p>Marburg virus disease poses a significant risk to global health, impacting both humans and non-human primates. This study has yielded an optimal control model for potentially mitigating the transmission of the Marburg infection. The proposed mathematical model includes fractional-order derivatives in the Caputo sense. Initially, we analyzed the model without control measures, examining its key characteristics regarding local and global stabilities. Subsequently, we extended the model by incorporating suitable time-dependent optimal control variables. We have also introduced two time-dependent control measures: $ \Psi_1 $ for the prevention of human-to-human Marburg transmission, and $ \Psi_2 $ to enhance the rate of quarantine of exposed individuals. We performed simulation analysis for both cases i.e., with and without optimal controls using the two-step Newton polynomial approximation method, considering both fractional and classical orders. The numerical findings of the comparative study between classical and fractional cases validate the biological significance of the fractional operator and effectiveness of the proposed optimal control strategies.</p></abstract>

Design and verification of low-friction and high-performance monotube magnetorheological damper

The frictional force of the suspension damper is an essential factor affecting vehicle ride comfort. As an important basic component of intelligent suspension, magnetorheological (MR) damper has the advantages of simple structure and adjustable damping performance. However, the frictional force of the MR damper is excessively high, due to the high-pressure gas to avoid the cavitation effect. If the frictional force of MR damper can be reduced, the vibration isolation performance of the intelligent suspension based on the MR damper will be further improved. In this study, a monotube MR damper with low friction and high performance is proposed and investigated. Firstly, the structural design of the low-friction MR damper is carried out, and the mathematical model of its controllable damping force and uncontrollable damping force is established. Secondly, the key structural parameters of the MR piston are optimized, and the valve system is matched based on the optimized mechanical characteristics of the piston to avoid the cavitation effect. Thirdly, bench tests are carried out on the developed low-friction MR damper. The experimental results show that the frictional force of the MR damper is very low, and no cavitation effect occurs. Finally, the system performance simulation analysis is carried out on the 1/4 vehicle semi-active suspension using the MR damper, and the influence of frictional force on the performance evaluation indexes of passive and semi-active suspensions is investigated. The simulation results indicate that the influence of frictional force on semi-active suspension is higher than that of passive suspension, and reducing the frictional force of the MR damper is of great significance to improve the performance of the semi-active suspension.

BIM-Based Building Performance Simulation Analysis: A Multi-Parameter-Driven Approach to Building Energy Efficiency and Carbon Reduction

Global warming and other environmental problems are increasing the demand for high-performance buildings. The development of high-performance computers and building information models has a significant impact on buildings’ energy simulation. High-performance building design needs to comprehensively consider geography, climate, material, cost and other factors which is a highly complex multidisciplinary research problem. Therefore, it is urgent to use advanced modeling and simulation technology to realize it, involving Building Information Modelling (BIM), parametric design and cloud platform. Comprehensive simulation of building performance refers to a multidisciplinary collaborative design, and the correlation between research objects and parameters should be achieved by complex programming design. This study integrates BIM, computer, cloud computing and other technologies to simulate BIM-based building energy consumption performance. Based on project information, geometry information and physical properties exhibited by materials stored in BIM model, the energy analysis model is created. Revit–Dynamo API functions are employed to generate a novel BIM model in Revit after automatically changing and transferring user-defined parameters. BIM energy consumption model is converted into Green Building eXtended Markup Language (GBXML) file and uploaded to Green Building Studio (GBS) cloud server. The optimal project solution is yielded by retrieving the energy consumption simulation results of BIM models with a range of parameters. The case study shows that building volume, glass material, window-wall ratio and window height have significant influence on energy consumption targets of buildings. In hot-summer and cold-winter areas, the total energy consumption of glass materials with high insulation and reflection coefficient is small. The window size slightly impacts the annual lighting energy consumption, but it has significant influence on the annual air conditioning energy consumption, with a maximum increase of about 22%. Finally, the application advantages and limitations of the framework in high-performance building design and its application prospects in energy-saving building design are discussed.

Exploring tools and indicators to support collaborative planning, design, implementation, operation, and evaluation of Positive Energy Districts

The study defines an integrated parametric workflow to support PED collaborative design and implementation. Through a preliminary detailed analysis, existing tools for urban building performance simulation and microclimatic analysis were identified, tested, and selected, aiming at maximising their interoperability potential and overall support to collaborative PED planning practices. Subsequently, it is illustrated how to conduct an ex-post simulation analysis of medium and long-term interventions, with specific projections of different scenarios considering climate change impacts on energy demand. The evaluation of the proposed climate-adaptive interventions takes place using tools for the optimization of systems and technical solutions at the basis of the energy surplus and decarbonization of districts and neighbourhoods. The aim of this research is twofold: i) shading light on the absence of data management, especially at the initial stages of the PED project, resulting in uncertainty and slow-down of the whole implementation process, as well as associated difficulties to trigger virtuous replicability processes towards inclusive urban energy transitions; and ii) promoting the adoption of tools and integrated climate adaptation and mitigation frameworks to support collaborative planning and evaluation of Positive Energy Districts.

Simulation Analysis of Sealing Performance of Rubber Core of Rotary Blowout Preventer

The performance of rotary control head or rotary blowout preventer will directly affect the success or failure of the underbalanced construction of oil and gas well. Once the failure occurs in the construction process, there may be blowout and other big drilling accidents. Based on the Yeoh constitutive equation, the dynamic sealing model of rubber core is established in this paper, and the sealing process of rubber core during tripping and tripping is calculated and analyzed. Then, the effect of the bubble defect in the core on the sealing performance of the core under different drilling fluid pressure was analyzed. Finally, the effect of metal degumming on the sealing performance of the core was analyzed. The results showed that the larger the initial sealing pressure and contact stress value of the Mises core was, the better the sealing effect of the Mises core was, while the larger the Mises stress value was, the more likely the Mises core was to suffer fatigue failure. The drilling fluid pressure significantly affects the maximum equivalent stress of the core, and the maximum equivalent stress appears in the bubble position inside the core at different times and under different drilling fluid pressure. The degumming position is placed in the contact position between metal and rubber core. When the tensile stress exceeds the limit of rubber core material, radial and circumferential cracks will occur on the upper surface of rubber core. With the increase of drilling times, rubber is prone to fatigue cracks, which eventually lead to mutual tearing.

FPGA-Based Extremum Seeking Control to Maximize the Hydrogen Productivity Rate of a MEC

In this article it is presented an FPGA-based extremum seeking control that is used to maximize the hydrogen productivity rate in a microbial electrolysis cell (MEC) using the dilution rate as a control action. This extremum seeking control is based in the hydrogen productivity gradient and does not need a mathematical model. To achieve a positive energy balance, such optimization algorithm is implemented in an FPGA using a fixed point representation. By a closed loop simulation test and performance analysis of the FPGA-based extremum seeking control, it is demonstrated that FPGAs are the best implementation choice.