Computer Simulation Tests Research Articles

Accurate Identification for CW Direct Signal in Underwater Acoustic Ranging

The underwater channel is bilateral, heterogeneous, uncertain, and exhibits multipath transmission, sound line curvature, etc. These properties complicate the structure of the received pulse, causing great challenges in direct signal identification for ranging purposes and impacts on back-end data processing, even accurate acoustic positioning. Machine learning (ML) combined with underwater acoustics has emerged as a prominent area of research in recent years. From a statistical perspective, ML can be viewed as an optimization strategy. Nevertheless, the existing ML-based direct-signal discrimination approaches rely on independent assessment, utilizing a single sensor (beacon or buoy), which is still insufficient for adapting to the complex underwater environment. Thus, discrimination accuracy decreases. To address the above issues, an accurate CW direct signal detection approach is performed using the decision tree algorithm, which belongs to ML. Initially, the pulse parameter characteristics in the underwater multipath channel are investigated and the parameter models are built. Then, based on multi-sensor localization performance feedback, fusion characteristics for diverse pulse are created. Next, the pulse parameter characteristics are preprocessed to mitigate the impact of varying magnitudes and units of magnitude on data processing. Then, the decision tree is built to obtain the desired output results and realize accurate recognition of the ranging direct signals. Finally, the feasibility and reliability of this paper’s method are verified by computer simulation and field testing.

Nongradient-Based Tracking of Environmental Field Isolines in a Changing Medium by Dubins-Vehicle Type Robots

A non-holonomic robot of a Dubins-vehicle type moves in a changing resistant medium, like water or air. The objective is to exhibit the extension of a spatial phenomenon (e.g., a critically contaminated area) related to a dynamic environmental field (e.g., a distribution of the contaminant concentration). Specifically, the robot should arrive at a certain level set of the field and repeatedly sweep it afterwards. The field data comes exclusively from online and point-wise measurements of the field value at the current location of the robot. An additional problem is related to the significant uncertainty on the field and the medium, including their variation with time and the effect of the medium on the robot's motion. The conditions for the accomplishability of the mission objective are found under these uncertainties and constraints on the kinematics of the robot. A navigation algorithm is presented that solves the mission with a slight enhancement of these necessary conditions. The performance of the algorithm is rigorously justified by the non-local convergence result and validated by computer simulation tests with a 6-DOF catamaran-like vessel and real-world environmental data.

Performance of Lower Ventilation Opening to Improve Air Change per Hour in Classroom at Tropical Humid Region (Case Study: Palembang City)

Fresh air circulation in a room had an impact on indoor air quality. In today’s pandemic, good fresh air circulation is one of the main strategies to prevent viruses from spreading through air molecules. A good ventilation opening design influences indoor air exchange. This research conducts a test on lower ventilation opening design that can maximize natural ventilation performance in a classroom. This test aimed at a recommendation for schools in the tropical humid region so they can hold offline learning with low virus spreads. Natural ventilation optimization should be a solution because not everyone can afford mechanical air filters or virus killers. This research used an experimental method. Computer simulation test variables were classroom openings consisting of existing openings, new outlets/openings, and lower ventilation opening. Parameters of observation are wind velocity, air circulation pattern, and air change per hour. This evaluation compares the experiment result to Air Change per Hour (ACH) threshold limit provision required in Indonesia. The result of the experiment shows outlet/opening addition provides a better impact on ACH escalation than with only existing classroom opening. And when the existing opening is closed, lower ventilation opening had good performance in achieving the ACH threshold limit provision requirements which were 9,8 ACH.

The simplified equipment selection method for the cove lighting

Cove lighting has become a widespread way of interior lighting due to the current popularization of linear LED strips. It is a type of indirect lighting usually used as interior decoration. However, it is possible to use this lighting type to meet general lighting requirements. The work presents the theoretical description of the cove lighting effects and the results of computer simulation and experimental tests on the mock-up model. The accuracy of computer simulation of cove lighting is sufficiently high. Because of that, it was possible to carry out further simulation tests. The results determined how the individual components of the geometry of the illuminated room (height, surface area, and the location of cove lighting equipment) affect the obtained level of average illuminance and its uniformity. The main result of the work is the determination of a simplified procedure for selecting cove lighting equipment. Thus, it is possible to quickly determine the value of the luminous flux of the LED strips so that a proper level of average illuminance (with relatively high uniformity) in the interior with a known height and surface area is achieved. The proposed procedure may significantly facilitate the design of cove lighting for architects and engineers.

New concept on 100.74 kWp floating solar photovoltaic plant and a real mechanical failures assessment: Case of study at Santa Clara hydroelectric power plant reservoir in southern Brazil

Structural failures and partial sinking were assessed in a 100.74 kWp floating solar photovoltaic power plant installed in southern Brazil, at the Santa Clara HPP reservoir. Their occurred during a torrential rain of 159.6 mm, accompanied by wind gusts of 72 km/h, resulting in the platform losing its linearity and causing permanent deformations in the metallic structures. Computer simulation tests calculated the instantaneous forces to be greater than 22 kN. Repairs were carried out replacing the mobile longitudinal fastening elements between modules with rigid and semi-rigid sets. To prevent direct contact between the mooring modules and the PV platform, transverse footbridge lines and a new concept of anchorage modules were introduced, incorporating semi-rigid elements to absorb energy from impacts. Since then, the anchoring systems have been functioning, even under adverse subtropical climate conditions, as occurred in July 2023, with an extratropical cyclone with wind gusts of around 150 km/h.

End-Cloud Collaboration Navigation Planning Method for Unmanned Aerial Vehicles Used in Small Areas.

Unmanned aerial vehicle (UAV) collaboration has become the main means of indoor and outdoor regional search, railway patrol, and other tasks, and navigation planning is one of the key, albeit difficult, technologies. The purpose of UAV navigation planning is to plan reasonable trajectories for UAVs to avoid obstacles and reach the task area. Essentially, it is a complex optimization problem that requires the use of navigation planning algorithms to search for path-point solutions that meet the requirements under the guide of objective functions and constraints. At present, there are autonomous navigation modes of UAVs relying on airborne sensors and navigation control modes of UAVs relying on ground control stations (GCSs). However, due to the limitation of airborne processor computing power, and background command and control communication delay, a navigation planning method that takes into account accuracy and timeliness is needed. First, the navigation planning architecture of UAVs of end-cloud collaboration was designed. Then, the background cloud navigation planning algorithm of UAVs was designed based on the improved particle swarm optimization (PSO). Next, the navigation control algorithm of the UAV terminals was designed based on the multi-objective hybrid swarm intelligent optimization algorithm. Finally, the computer simulation and actual indoor-environment flight test based on small rotor UAVs were designed and conducted. The results showed that the proposed method is correct and feasible, and can improve the effectiveness and efficiency of navigation planning of UAVs.

Locomotion characteristics of a wheeled vibration-driven robot with an enhanced pantograph-type suspension.

Introduction: The paper considers the improved design of the wheeled vibration-driven robot equipped with an inertial exciter (unbalanced rotor) and enhanced pantograph-type suspension. The primary purpose and objectives of the study are focused on mathematical modeling, computer simulation, and experimental testing of locomotion conditions of the novel robot prototype. The primary scientific novelty of the present research consists in substantiating the possibilities of implementing the enhanced pantograph-type suspension in order to improve the robot's kinematic characteristics, particularly the average translational speed. Methods: The simplified dynamic diagram of the robot's oscillatory system is developed, and the mathematical model describing its locomotion conditions is derived using the Euler-Lagrange differential equations. The numerical modeling is carried out in the Mathematica software with the help of the Runge-Kutta methods. Computer simulation of the robot motion is performed in the SolidWorks Motion software using the variable step integration method (Gear's method). The experimental investigations of the robot prototype operating conditions are conducted at the Vibroengineering Laboratory of Lviv Polytechnic National University using the WitMotion accelerometers and software. The experimental data is processed in the MathCad software. Results and discussion: The obtained results show the time dependencies of the robot body's basic kinematic parameters (accelerations, velocities, displacements) under different operating conditions, particularly the angular frequencies of the unbalanced rotor. The numerical modeling, computer simulation, and experimental investigations present almost similar results: the smallest horizontal speed of about 1mm/s is observed at the supplied voltage of 3.47V when the forced frequency is equal to 500rpm; the largest locomotion speed is approximately 40mm/s at the supplied voltage of 10V and forced frequency of 1,500rpm. The paper may be interesting for designers and researchers of similar vibration-driven robotic systems based on wheeled chassis, and the results may be used while implementing the experimental and industrial prototypes of vibration-driven robots for various purposes, particularly, for inspecting and cleaning the pipelines. Further investigation on the subject of the paper should be focused on analyzing the relations between the power consumption, average translational speed, and working efficiency of the considerer robot under various operating conditions.

Numerical and experimental analysis of the heat transfer process in a railway disc brake tested on a dynamometer stand

Abstract The effectiveness of railway brakes is highly dependent on the thermal condition of the brake disc and friction linings. An effective research method for the heat transfer process in brakes was computer simulation and experimental tests on a full-size dynamometric test bench. A two-dimensional, axially symmetric numerical model of transient thermal conductivity in a railway brake was presented. Appropriate boundary conditions of the problem were applied, describing the heat generated in the brake and discharged to the environment. The problem was solved using the finite-element method. This article presents exemplary results of the brake temperature calculations obtained using the numerical model and the results of experimental tests carried out on two types of brake discs.

Two-fidelity Data Fusion Modeling with Particle Swarm Sampling

Computer simulation and experimental testing are commonly used means of data acquisition in industrial design, so the combination of low-precision data represented by cheap calculation data and high-precision data represented by expensive test data for fusion modeling is a hot topic in practical applications question. In order to improve the quality of the model and control the usage of high-precision data, this paper proposes a double-precision fusion modeling method based on particle swarm sampling. The algorithm uses the Kriging model to model high- and low-precision data, and uses PSO (Particle swarm optimization) to obtain low-precision model information for high-precision modeling. Combined with the characteristics of sufficient amount of low-precision data, high-precision data is expensive and difficult to obtain, the low-precision model modeled after sufficient sampling is used to guide the initial sampling of the high-precision model, and the fusion model is obtained by training with two high-precision and low-precision models, and two The point-adding criterion is used for sequential modeling, and the fusion model is continuously optimized. The algorithm is tested on a standard function and an application problem. The experimental results show that the algorithm improves the quality of the modeling without increasing the amount of high-precision data, which verifies the effectiveness of the proposed algorithm.

Concept development, design and validation of a novel continuous casting equipment

PurposeThe purpose of this paper is to develop a concept and design to cast Al alloys/metal matrix composites (MMCs) by continuous casting process. The various steps involved in the evolution of the design have been reported and discussed in this study.Design/methodology/approachOn the basis of developed design concept, initial prototype design has been prepared in this study. The casting process's melt flow pattern was studied via computer simulation, and the resulting changes were implemented in the original design. The single-phase fluid flow pattern through bottom feeding technique is studied. The equipment was fabricated based on computer simulation and water modelling studies. Finally, validation was performed for the preparation of Al alloys/ MMCs after parameter optimisation. The results were observed in the optical metallography to confirm the alloying and Al MMC preparation.FindingsThe developed continuous casting process with bottom feeding technique for the addition of constituent particles shows more efficiency in comparison to the existing batch processes. The final manufactured setup demonstrates effective Al alloy/MMC production as the basis for final fabrication has been accomplished by both computer simulation and water model test. In addition, the microstructure exhibits homogeneous distribution, validating the reliability of the setup.Originality/valueIntegrating continuous casting with continuous reinforcement or master alloy addition is novel in this area. The constraints that batch production had that have been rectified will also lower the contemporary cost of production.

A High-Voltage Gain Non-Isolated DC–DC Converter Designed for Bipolar DC Microgrids

DC microgrids are now starting to attract huge attention from researches and engineers. Among the several DC microgrid architectures, bipolar DC microgrids are advantageous to accommodate a wider range of DC loads. However, due to mismatched loads connected to the two poles, bipolar DC microgrids may show voltage balancing issues. In this context, this article presents a new high input-to-output voltage gain, non-isolated DC–DC converter specifically designed for bipolar DC Microgrids. The proposed converter supports the balance of voltages at both bipolar DC microgrid poles, as the converter can transfer energy between the two poles in an unbalanced way. The description, theoretical support, and operation of the proposed converter will be presented. The theoretical assumptions will be complemented with several results obtained from computer simulation tests. The simulation tests will be compared to laboratory results from an experimental prototype. The obtained results confirm the theoretical properties of the proposed converter.

Bionic Design of Liquid Fertilizer Deep Application Spray Needle, Based on Badger Claw-Toe, for Improving the Operating Performance of Liquid Fertilizer Deep Application in Northeast China

Deep application of liquid fertilizer is a technique that applies liquid fertilizer deep near the root system of crops, which has many advantages such as high fertilizer utilization rate and low environmental pollution. However, high power and high specific energy consumption caused by soil-engaging components in liquid fertilizer deep application make it difficult to popularize in northeast China. The claw-toe structure of burrowing animals has the characteristics of low resistance and low friction, which has been the focus of many scholars’ research on soil-engaging components. The claw-toe structure of the badger, a widely distributed burrowing animal in northeast China, has good characteristics of low power and low specific energy consumption. Therefore, in this research, a bionic liquid fertilizer deep application spray needle was designed, based on the claw-toe structure of the badger, to improve the operating performance of liquid fertilizer deep application. In this research, the discrete element method (DEM) was used for a computer simulation test, and the indoor soil bin verification test was carried out. The results showed that the operating angle, operating speed and fertilization depth of bionic liquid fertilizer deep application spray needle had significant effects on the power and specific energy consumption, and the optimal operating performance combination of bionic liquid fertilizer deep application spray needle was obtained as follows: The fertilization depth is 60 mm; the operating speed is 6 km h−1; the operating angle is 24.8°; the power consumption is 0.066 kW; and the specific energy consumption is 4.257 kJ m−3 under this operating condition. Through the comparison of operating performance, the operating performance of the bionic liquid fertilizer deep application spray needle is significantly better than that of other types of liquid fertilizer deep application furrow opener, with the power reduced by 9.52~40.5% and the specific energy consumption reduced by 93.9~208.6%. This research clarified the internal mechanism affecting the operating performance. Finally, based on the above findings, this research suggests that more attention should be paid to finding suitable bionic prototype and design scheme in the future design and research of soil-engaging components of liquid fertilizer deep application.

A simulation test of the prediction that density-dependent dispersal promotes female-biased sex allocation in viscous populations.

A classic result of sex-allocation theory is that the sex ratio is predicted to be invariant with respect to the rate of dispersal. However, a recent mathematical analysis has suggested that if individuals are able to adjust their probability of dispersal according to the local density of their neighbourhood, then a lower rate of dispersal will be associated with greater female-bias. Here, we perform a computer simulation test of this prediction. Our simulation data provide strong qualitative support for the prediction, and a Monte Carlo randomization test of significance allows us to reject the null hypothesis of the invariance relationship.

A determination method for the shear strength of soil-rock mixture considering the size effect and its application

The shear strength of the soil-rock mixture (S-RM) is the primary mechanical factor influencing the stability of the deposit slope. The particle size range inside the test sample, however, is not the same as that of the S-RM in the deposit slope due to the limitations of the test device, which results in a variation in the mechanical properties. In this study, computer simulation tests were conducted to examine the impact of particle size on mechanical behaviors under the uniaxial compressive condition, and the size effect was analyzed from both macroscopic and mesoscopic perspectives. Results indicate that when the particle size increases, the anisotropy levels of the S-RM sample also rise, causing the particle displacement difference inside the sample to increase and the rounding rock effect to become more pronounced. The quantitative relationship between the uniaxial compressive strength (UCS) and the maximum particle size (dmax) was proposed, and the accuracy of the prediction formula for the UCS value of S-RM that takes the size effect into account has been confirmed. The improvement of the shear strength determination method was achieved by unifying the particle size range corresponding to the uniaxial compressive and shear test results used in the approach, and the determination method was used to evaluate the stability of a typical deposit slope. The study results can be used as a guide for estimating strength parameters of S-RM throughout the design and construction process of the deposit slope.

Information theoretic performance evaluation of 3D integral imaging.

Integral imaging (InIm) has proved useful for three-dimensional (3D) object sensing, visualization, and classification of partially occluded objects. This paper presents an information-theoretic approach for simulating and evaluating the integral imaging capture and reconstruction process. We utilize mutual information (MI) as a metric for evaluating the fidelity of the reconstructed 3D scene. Also we consider passive depth estimation using mutual information. We apply this formulation for optimal pitch estimation of integral-imaging capture and reconstruction to maximize the longitudinal resolution. The effect of partial occlusion in integral imaging 3D reconstruction using mutual information is evaluated. Computer simulation tests and experiments are presented.

Wireless Communication Signals: A Laboratory-Based Approach

The book provides a comprehensive set of tools for communication engineers and interested researchers for the analysis and design of wireless systems by discussing not only the basic theory, but also modeling, computer simulation, and hardware testing of the various building blocks of modern communication systems. The code snippets throughout the book enable readers to attain hands-on experience by implementing them on software and observing the effect of various parameters on the performance of the system. While the book is not explicitly divided into different parts, there is a general harmony and progression in the way the chapters are arranged. Considering the broad scope of this book and its in-depth coverage of many practical issues regarding modern wireless communication systems, we believe that it can be used as a textbook or a valuable reference for a senior undergraduate or graduate-level laboratory-orientied course focusing on wireless digital communications. The book is organized in such a way that it can be used to support various wireless and/or digital communication courses from beginner to advanced levels, and can serve as a reference for research projects of both undergraduate and graduate students. More importantly, the models and codes introduced in this book are universal and can be used in conjunction with any software-defined radio platform. Considering all these, this book is a valuable resource for our community.

Two Sound Field Control Methods Based on Particle Velocity

In recent years, a variety of sound field control methods have been proposed for the generation of separated sound regions. Different algorithms control the physical properties of the generated sound field to different degrees. The existing methods mainly focus on sound pressure restoration and its related improvement. When the loudspeaker array is non-uniformly placed, the reconstruction system is not stable enough. To solve this problem, this paper proposes two sound field control methods related to particle velocity. The first method regulates the reconstruction error of particle velocity in the bright zone and the square of particle velocity in the dark zone; the second method regulates the reconstruction error of sound pressure and particle velocity in the bright zone and the square of sound pressure and particle velocity in the dark zone. Five channel and twenty-two channel non-uniform loudspeaker systems were used for two-dimensional and three-dimensional computer simulation testing. Experimental results show that the two proposed methods have better tradeoffs in terms of acoustic contrast, reproduction error and array effort than traditional methods, especially the second proposed method. In the two-dimensional experiment, the maximum reductions of the average array efforts generated by the proposed methods were about 10 dB and 11 dB compared with the average array efforts generated by two traditional methods. In the three-dimensional experiment, the maximum reductions of the average array efforts generated by the proposed methods were about 8 dB and 2 dB compared with the average array efforts generated by two traditional methods. The smaller the array effort, the more stable the loudspeaker system. Therefore, the reconstruction systems produced by the proposed methods are more stable than those produced by the traditional methods.

The Importance of the Geometry of the Down Sprue in the Gravity Casting Process.

This article presents the results of experiments on the optimization of down sprue geometry in the process of pouring sand molds. Theoretical assumptions and computer simulation tests are presented. The starting point was the theory and experience of gas entrapment caused mainly by a poorly designed gating system and the down sprue. Simulations were performed using Magmasoft software. First, initial studies were carried out to determine how the geometry (mainly the channel cross-section) of the sprue affects the problem, and then a detailed experiment was carried out on the so-called ‘short sprue’ version. The air entrapment process was analyzed, as were the parameters of the liquid alloy flow that passes through the analyzed channels. Nine geometric versions of the sprue were proposed and analyzed, and the results allowed us to conclude which sprue geometry is the best from the point of view of minimization of the gas entrapment problem.

Reduction of the Electromagnetic Torque Oscillation during the Direct on Line (DOL) Starting of a 6 kV Motor by Means of a Controlled Vacuum Circuit-Breaker

This article deals with the issue of the reduction of the oscillation of electromagnetic torque in the case of a direct on line (DOL) starting of a 6 kV induction motor. Such engines are used in drive systems where frequent starting may be required. Direct starting in such systems may reduce the mechanical and thermal durability. Therefore, the article presents a method of DOL starting of a 6 kV induction motor with the use of vacuum circuit-breakers and appropriate switching of the voltages supplying the electric machine. To confirm the advantages of the proposed solution, computer simulation and experimental tests were carried out, which are presented and discussed in the article. The obtained results confirm the advantages of the proposed solution, compared to the classic starting known from the literature.

Numbers, Please: Power- and Voltage-Related Indices in Control of a Turbine-Generator Set

This paper discusses the proper selection and interpretation of aggregated control performance indices values mirroring the quality of electrical energy generation by a turbine-generator set cooperating with a power system. Typically, a set of basic/classical and individual indices is used in energy engineering to ensure the mirroring feature and is related to voltage, frequency and active or reactive power deviations from their nominal values desired in the power system. In this paper, aggregated indices based on the sum of weighted integral indices are proposed, verified and built based on the well-known indices originating from control theory. These include an integral of the squared error (ISE) and an integral of the squared error multiplied by time (ITSE), applicable whenever an in-depth analysis and evaluation of various control strategies of the generation system is to be performed. In the reported research, the computer simulation tests verified their effectiveness in assessing the generated electricity on the example of a turbine-generator set controlled using a predictive control technology as well as applicability, proven by numerous simulation results to take various and different in nature requirements into account efficiently, in the form of a single aggregated index.