Middle Speed Research Articles

Analysis of the Flow Capacity of Variable Cycle Split Fans at the Middle Speed

The next-generation variable cycle engine imposes stricter requirements on a fan’s flow capacity at the middle speed. To tackle this challenge, the implementation of split fans presents as a potential solution. In the present study, we conducted numerical simulations using the commercial software NUMECA to investigate the aerodynamic performance variation with bypass ratios for variable cycle split fans in “1 + 2” and “2 + 1” configurations at 80% rpm. The results indicate that the flow capacity of the split fans exhibits an increasing trend with a rise in the bypass ratio at 80% rpm and subsequently stabilizes upon reaching a certain bypass ratio. Specifically, the flow capacity of the “2 + 1” split fans is particularly stronger at the small bypass ratios, whereas the “1 + 2” split fans exhibit superior maximum flow capacity at the high bypass ratios. Additionally, there is a significantly faster increase in the flow capacity of the “1 + 2” split fans compared to that of the “2 + 1” split fans. Furthermore, when the flow capacity of the split fans reaches its maximum, both the efficiency and stall margin achieve their optimal values, indicating that the corresponding bypass ratio is optimal.

Calculation and experimental determination of the speed of advancement of the plasma leader channel of a pulse spark discharge in atmospheric air

Goal. Calculation and experimental determination of middle speed vL of advancement of plasma leader channel of a pulse spark discharge in the long air interval of the double-electrode discharge system (DEDS) «tip-plane». Methodology. Bases of the theoretical electrical engineering and electrophysics, electrophysics bases of technique of ultra- and high-voltage and high pulse currents, bases of high-voltage pulse technique and measuring technique. Results. The close calculation and experimental method of determination of middle speed vL of advancement of plasma leader channel of an electric pulse spark discharge is offered in the long air interval of DEDS «tip-plane». This method is based on the offered calculation empiric formula for finding of the indicated speed vL and results of decoding of oscillograms of process of cut of in-use standard interconnect аperiodic pulse of over- and high-voltage of temporal shape of Tm/Тd≈200 μs/1990 μs of positive polarity at an electric hasp in indicated DEDS of long air intervals with their minimum length of lmin, numeral making 1,5 m (first case) and 3 m (second case). It is shown that middle speed vL of advancement in atmospheric air of front of plasma channel of positive leader of an electric pulse spark discharge in probed DEDS «tip-plane» for two considered applied cases at lmin=1,5 m of lmin=3 m numeral makes approximately vL≈(1±0,03)∙105 m/s. The found numeral value of this speed vL well coincides with the known experimental information for speed of advancement of vL≈105 m/s in atmospheric air of plasma channel of negative leader for a long storm spark discharge in DEDS «charged cloud-earth». It is set that for the standard interconnect аperiodic pulse of high- and ultra- voltage of temporal shape of Tm/Тd≈200 μs/1990 μs of positive polarity middle value of aggressive strength Ed of high pulse electric field in the air interval of probed DEDS «tip-plane» numeral makes minimum length of lmin=1,5 m near Ed1≈360,8 kV/m, and for his minimum length of lmin=3 m of − Ed2≈313,4 kV/m. Originality. The comfortable is developed in the use and reliable in practical realization technicians-and-engineers calculation and experimental method of research in the conditions of high-voltage electrophysics laboratory of difficult electro-discharge processes of development of leader hasp of long air intervals and determination of minimum electric durability of air insulation of electrical power engineering and electrophysics equipment on working voltage of classes of 330-1150 kV. Practical value. Application in area of industrial electrical power engineering and high-voltage pulse technique of the got numeral electrophysics results and offered calculation and experimental method of determination of middle speed vL of advancement in atmospheric air of plasma channel of leader of a long spark discharge will allow, from one side, to deepen our scientific knowledges about a long electric pulse spark discharge in an air dielectric, and, from other side, to develop high-voltage electrical power engineering and electrophysics devices with enhanceable reliability of their work both in normal operation and malfunctions.

Effects of Operating Conditions during Three-Layered Polymeric Balloon Catheter Extrusion

Multilayered balloon catheters are attracting more attention in recent years. Multilayered balloon catheters have some unique properties such as meso-/microscale dimensions, small wall thickness, and strict requirements of dimensional accuracy. In this study, three-layered polymeric balloon catheters composed of polyamide, ethylene vinyl acetate, and polypropylene (PA/EVA/PP) are successfully fabricated using a three-layered coextrusion die and the polymer melt flowing behavior through the extrusion die are analyzed. Both the diameter and wall thicknesses have been selected as the targeted structural parameters to investigate the effects of pulling speed, air injection volume rate, and screw speed on the quality of the extrudates. The optimal combination of these three operating conditions has been achieved. It is found that pulling speed can significantly affect the diameters of the extruded balloon catheters. The variation interval values of outer profile diameter and inner cavity diameter with the extrusion experiments are 20.95% and 13.04%, respectively. The screw speed of each layer has a great influence on the wall thickness of each layer. Through the influence of outer screw speed, middle screw speed and inner screw speed, the variation interval values for outer layer wall thickness, middle layer wall thickness, and inner layer wall thickness are 31.06%, 35.69%, and 31.35%, respectively. The air injection volume rate has negligible effect.

Yarn unevenness prediction using generalized regression neural network under various optimization algorithms

Unevenness is one of the important parameters for evaluating yarn quality, but the current prediction accuracy of yarn unevenness is low. One of the important reasons is that there are few sample dataset for yarn unevenness prediction. For this problem, this paper applies generalized regression neural network to predict the unevenness of the yarn. Then, the generalized regression neural network is optimized by using particle swarm optimization, fruit fly optimization algorithm, and gray wolf optimizer, respectively. Finally, the optimized models were experimentally validated for their effectiveness. The experimental results show that the generalized regression neural network optimized by gray wolf optimizer has the best effect and the fastest optimization speed; the generalized regression neural network optimized by particle swarm optimization algorithm has the middle optimization speed; the generalized regression neural network optimized by fruit fly optimization algorithm has the worst effect and the slowest optimization speed.

Suppression effects of excitatory and inhibitory self-feedbacks on neuronal spiking near Hopf bifurcation

Neural activities driven by synaptic inputs are important for neural coding. In general, excitatory synaptic inputs facilitate the firing activities of neurons, and inhibitory synaptic inputs suppress the firing activities. In the present work, the autapse model with adjustable current decay speed is considered, and the suppression effects of excitatory autapse on neuronal firing responses are simulated near subcritical Hopf bifurcation in the Morris-Lecar (ML) neuron model, which are compared with the suppression effects of the inhibitory autapse. Furthermore, the dynamical mechanisms of the suppression effects are acquired with the help of the phase response curve and phase trajectories perturbed by excitatory autaptic current. Near the subcritical Hopf bifurcation, the ML neuron exhibits monostable periodic spiking and coexistence of periodic spiking and resting state. For monostable periodic spiking, excitatory autaptic current with fast and middle decay speeds can induce the periodic spiking with reduced firing frequency and the mixed-mode oscillations (MMOs) that are alternations between subthreshold oscillations and a spike, respectively, and inhibitory autaptic current with middle and slow decay speeds can also induce these two behaviors, respectively. For the periodic spiking in the coexistence region, besides the above two behaviors, excitatory autaptic current with middle decay speed and inhibitory autaptic current with slow decay speed can induce the change from spiking to resting state. The results enrich the paradoxical cases that excitatory inputs suppress the neuronal firing responses, and present the different nonlinear mechanisms in the suppression effects of excitatory and inhibitory self-feedbacks on the neuronal spiking, which provide novel measures to modulate neuronal firing activity.

Influence of Controller’s Parameters on Static Bifurcation of Magnetic-Liquid Double Suspension Bearing

Magnetic-Liquid Double Suspension Bearing (MLDSB) is composed of an electromagnetic supporting and a hydrostatic supporting system. Due to greater supporting capacity and static stiffness, it is appropriate for occasions of middle speed, overloading, and frequent starting. Because of the complicated structure of the supporting system, the probability and degree of static bifurcation of MLDSB can be increased by the coupling of hydrostatic force and electromagnetism force, and then the supporting capacity and operation stability are reduced. As the key part of MLDSB, the controller makes an important impact on its supporting capacity, operation stability, and reliability. Firstly, the mathematical model of MLDSB is established in the paper. Secondly, the static bifurcation point of MLDSB is determined, and the influence of parameters of the controller on singular point characteristics is analyzed. Finally, the influence of parameters of the controller on phase trajectories and basin of attraction is analyzed. The result showed that the pitchfork bifurcation will occur as proportional feedback coefficient Kp increases, and the static bifurcation point is Kp = −60.55. When Kp < −60.55, the supporting system only has one stable node (0, 0). When Kp > −60.55, the supporting system has one unstable saddle (0, 0) and two stable non-null focuses or nodes. The shape of the basin of attraction changed greatly as Kp increases from −60.55 to 30, while the outline of the basin of attraction is basically fixed as Kp increases from 30 to 80. Differential feedback coefficient Kd has no effect on the static bifurcation of MLDSB. The rotor phase trajectory obtained from theoretical simulation and experimental tests are basically consistent, and the error is due to the leakage and damping effect of the hydrostatic system within the allowable range of the engineering. The research in the paper can provide theoretical reference for static bifurcation analysis of MLDSB.

Position sensorless starting method for IPMSMs by all‐pass filters

AbstractThis paper proposes the starting method for position sensorless controlled interior permanent magnet synchronous motors (IPMSMs) by using all‐pass filters. The starting of IPMSM position sensorless control is well known to be extremely difficult due to the lack of electromotive information. Therefore, IPMSM is often started and accelerated with the high‐frequency signal injection in general, and then, the control algorithm is switched to position sensorless control without high‐frequency injection in middle speed region. However, the acoustic noise due to high‐frequency signal injection would occur, and the switching of control methods would cause some bumps. For this reason, IPMSM is desirable to be driven from the start to the steady state without high‐frequency signal injection.This paper realizes to start the position sensorless controlled IPMSM without high‐frequency signal injection by allpass filter with the assistance of the appropriate initial vector setting of each controller, under the assumption that the high‐frequency signal injection is used only at standstill. Finally, this paper experimentally demonstrates the feasibility and the effectiveness of the proposed method.

Control of magnetically levitated rotors using stabilizing effects of gyroscopes

Stable control of magnetically levitated rotors with a high gyroscopic effect is an important subject in the field of rotating machinery. This paper describes a method to address this problem using a cross-coupled control approach. In the low and middle speed range a constant diagonal controller and a speed dependent cross-coupled controller is used. In the high speed range the controller takes advantage of the stabilizing effect of gyroscopes. Hence, no positive diagonal stiffness is required in the high speed range in the tilting control path. The damping of the nutation and precession mode is provided only by the cross-coupled control paths. Thus, no diagonal controller is required for the stabilization of the tilting modes. This circumstance reduces the gain and the bandwidth of the control structure, and therefore decreases the impact of sensor noise and the possibility of destabilizing high frequency flexible modes. In this study the stabilizing effect of magnetically stabilized gyroscopes is derived analytically. Furthermore, the damping effects of the cross-coupled controllers are explained, using the eigenvalues of a simplified system. Simulation results show the output sensitivity of the control structures. Based on this knowledge, the optimal switching point between the control structures can be derived. Finally, experimental results on a turbo-molecular pump validate the effectiveness of the proposed control method.

Improved Current Profile Selection for Noise Reduction of Switched Reluctance Motor at Middle Speed Considering Back EMF

An improved current profile selection for noise reduction of a switched reluctance motor (SRM) during middle-speed operation is presented with the principle of flattening the three-phase radial force sum. The improved current is selected from the proposed algorithm, which considers the limited input voltage and back electromotive force influence at middle-speed operation. The improved current profile is compared with the single pulse current, which is the typical current for SRMs at middle-speed operation. The analysis results show that the variation of the radial force sum by the improved current profile is less than that of the single pulse current, although the influence of the back electromotive force is high. The effectiveness of radial force sum flattening is verified by the experimental results. The experiments were carried out with the downscaled operating point of a SRM owing to the limited range of the operating speed. The experiment results show a significant reduction in the highest and second-highest peak noises at 5.4 and 1.8 kHz by 11.04 and 17.51 dB, respectively, with the improved current profile. The other noises were also reduced.

Features of Work of Electric Locomotive Transport in the Conditions of Iron-Ore Mines

In the article the results of research of work of mine electric locomotive transport are driven. It is marked that increase of power efficiency of electrical equipment of mine are a necessary condition for the increase of booty of iron-ore raw material. Decision of task of increase of booty of iron-ore raw material related to development and improvement of underground transport. Forming of structure of moving of iron-ore raw material takes place under influence of many mining-and-geological, technical, technological and organizational factors that influence on the size of stream of the moved loads casual character. This is determine casual character of stream of raw material that is transported. Mine electric locomotives are the basic type of transport that is used for moving of minerals within the limits of mountain drift. A model, that describes work of one electric locomotive enroute, that serves one point in that there is loading of minerals with one claotype ways, was considered. Realization of burst performance of mine electric locomotive is possible at reduction of time of his outages, that results in reduction of time of voyage and increase of middle rate of movement of rolling stock. Research of work of electric locomotive transport in the conditions of iron-ore mine was shown, that time of voyage was in limits from 440 to 530 seconds, middle speed here changes a from 1,2 to 1,78 m/s, and distance, that passes an electric locomotive in times of one voyage, makes from 596,7 to 796 meters. Importance of the modes of starting and braking was shown for realization of maximal properties on coupling of wheels of electric locomotive with rails and increase of the productivity of mine electric locomotives, and also factors that influence to work of mine electric locomotives in the mode of braking are considered. For the power supply of mine electric locomotives a device is used for connecting to parts being under electric tension. This device, pantograph, by means of the special wire, carries out a contact and connecting of electric parts of electric locomotive to the electric station. On the value of tension of the electric station influences circumstance that she is connected to the sections of tires that conduct an electric current, to that other, more power-hungry consumers are connected. So, for example, at starting of a main vent setting, by power 1600 kilowatts, there is a considerable decline of output tension value of that were fixed in limits from 195 to 276 Volt. It becomes possible because of influence of powerful electrical equipment on work of other electrical equipment in the group systems of power supply. Partly this question can be decided due to the use of the systems facilitating starting of electrical equipment. Basic factors, that influence to work of mine electric locomotives there are such that directly operate on the electromechanics system in the zone of contact of wheel with a rail (coefficient of rolling friction of wheels of electric locomotive with rails), and pantograph with a pin wire (level of tension of power supply of electromechanic). Therefore influence of these factors must be necessarily taken into account during work of mine electric locomotives. Other factors have casual character, and works of electric locomotives do not operate at all time, therefore, for reduction of their influence, a sufficient condition is implementation of preventive measures, such as introductions of the systems of the smooth starting, application of algorithms power effective management, systems of monitoring and diagnostics of work of equipment. The presence of wide range of initial conditions, such as variation of coefficient of rolling friction and rate of movement of electric locomotive, stipulates complication of calculations of descriptions of retrosystem.

An investigation on discharge servo parameters and machining servo mode optimization of MS-WEDM

Increasing the machining efficiency of middle speed wire electrical discharge machining (MS-WEDM) is usually through optimizing process parameters, but the discharge servo parameters of the servo controller can also be optimized to achieve the same purpose. This paper develops a multi-mode servo controller for MS-WEDM to investigate discharge servo parameters. Firstly, the structure and control principle of the servo controller are introduced, and the core functions are described in detail. Secondly, it introduces the discharge servo parameters that can be optimized: gap state threshold and feedback period. At the same time, the platform specifications and parameters for optimization experiments are introduced. Thirdly, the experimental scheme and result analysis of parameter optimization are described, and the optimized parameters are obtained. Finally, different machining experiments are carried out for the multi-mode of the servo controller to investigate the effectiveness and practicability of the different machining servo modes. In the parameter optimization and machining experiments, the recording function of the servo controller was used to draw the speed curve, and the servo response effects of different servo modes were obtained.

The Pressure-Speed Control of 555 Timer Circuit for Flow-Controlled Booster Motor by Solar Cell

This paper presents the application of 555 timer circuit. For general PWM control circuit components manner and cost reduction improvements, and apply this system of automatic flow-controlled motor. We use pressure switch to control the rpm of automatic flow-controlled motor. And then, it can enhance the water pressure due to a water tower lack. The system can reach the target of energy –saving and environment friendly by using solar energy. Finally, the consumer can adjust the water flow volume by choosing low speed, middle speed, and high speed of permanent magnet DC motor revolution due to pressure switch control. Keywords: Solar cell, 555 timer circuit, PWM control circuit, Flow-controlled booster motor, Pressure switch.

Nonlinear tribo-dynamic model and experimental verification of a spur gear drive under loss-of-lubrication condition

Gearbox is required to serve for ≥ 30 min in helicopter design to improve survivability, when the gear drive loses lubrication due to battle damage. Under such loss-of-lubrication condition, tooth friction, wear and temperature pose serious problems to dynamic performance of gears. Therefore, a nonlinear tribo-dynamic model of spur gear drives is established and experimentally validated in this work. The time-varying friction coefficient is predicted under loss-of-lubrication condition on the basis of computational inverse technique. The temperature rise and tooth wear caused by friction were included by using thermal network model and dynamic wear model. The flexibility of gear shafts and the gyroscopic effect of gear rotors are also considered. The results indicate the gyroscopic effect apparently affects the natural frequency of the gear drive, while friction has negligible effect on the natural frequency but has considerable effect on the nonlinear behavior. The influence of temperature and gyroscopic effect on nonlinear behavior are reflected in the region of middle and high speed, while tooth wear mainly affects the bifurcation at the middle speed. In addition, tooth wear not only aggravates gear vibration but also can change the phase of dynamic transmission error. The analysis and experiment results can be an important reference in reducing friction and wear, restraining nonlinear behavior, and reducing vibration and noise.

The effect of different loading patterns on the resistance to shear flow of hot mix asphalt

The aim of this study was to evaluate the performance of hot mix asphalt against shear deformations. Loading axles (single, tandem and tridem) as well as vehicle speed were considered as research variables. The combination of research variables creates different loading scenarios with different loading pulse times. Using theoretical principles, loading scenarios similar to the field mode were simulated. Then, using the repeated load uniaxial test (RLUT), a quantitative analysis was performed on the mentioned variables. Flow number (FN) and tertiary flow (TF) were used as quantitative output parameters to analyze the test results. In addition, the regression coefficients of the power-law model represent the effect of initial densification and shear flow. It was observed that at higher speeds and in the mode of multiple axles, the initial densification had more effect on the permanent strain compared to the effects of the shear flow. On the other hand, in the single axle, the shear flow was the dominant factor at all speeds. At the middle speed (60 km⁄h), the shear flow (the slope) was the dominant parameter for the tridem axle. Low pulse times, high speeds and proximity of the load impact peaks can cause higher initial densifications in multiple axles. It was also indicated that by increasing the number of axles, values of the FN and the TF, and the value of the interval between these two parameters reduced. This reduction became more tangible by increasing the number of axles from single to other axle modes. In all axle modes, by increasing the speed, the FN and the TF increased. The rate of these increases was higher when transitioning from low speed (20 km⁄h) to middle speed (60 km⁄h) was more intense. Therefore, low speeds had more destructive effects. Thus, higher speeds reduced the destruction effects of multiple axles loads and increased the service life of the mixtures, and improved their performance against shear deformations.

Modelling A Single-Rotor Wankel Engine Performance With Artificial Neural Network At Middle Speed Range

The researches on Wankel engines are very rare and considered new in modelling and prediction. Therefore this study deals with the artificial neural network (ANN) modelling of a Wankel engine to predict the power, volumetric efficiency and emissions, including nitrogen oxide, carbon dioxide, carbon monoxide and oxygen by using the change of mean effective pressure, intake manifold pressure, start of ignition angle and injection duration as inputs. The experiment results were taken from a research which is performed on a single-rotor, four stroke and port fuel injection 13B Wankel engine. The number of datas which are taken from experimental results were scarce and varied in six different data set (for example; mean effective pressure, from 1 to 6 bar) at 3000 rpm engine speed. The standard back-propagation (BPNN) Levenberg-Marquardt neural network algorithm is applied to evaluate the performance of middle speed range Wankel engine. The model performance was validated by comparing the prediction data sets with the measured experimental data. Results approved that the artificial neural network (ANN) model provided good agreement with the experimental data with good accuracy while the correlation coefficient R varies between 0.79 and 0.97.

Conceptual Approach on Feasible Hydrogen Contents for Retrofit of CNG to HCNG under Heavy-Duty Spark Ignition Engine at Low-to-Middle Speed Ranges

Hydrogen-based engines are progressively becoming more important with the increasing utilization of hydrogen and layouts (e.g., onboard reforming systems) in internal combustion engines. To investigate the possibility of HICE (hydrogen fueled internal combustion engine), such as an engine with an onboard reforming system, which is introduced as recent technologies, various operating areas and parameters should be considered to obtain feasible hydrogen contents itself. In this study, a virtual hydrogen-added compressed natural gas (HCNG) model is built from a modified 11-L CNG (Compressed Natural Gas) engine, and a response surface model is derived through a parametric study via the Latin hypercube sampling method. Based on the results, performance and emission trends relative to hydrogen in the HCNG engine system are suggested. The operating conditions are 1000, 1300, and 1500 rpm under full load. For the Latin hypercube sampling method, the dominant variables include spark timing, excess air ratio (i.e., λCH4+H2), and H2 addition. Under target operating conditions of 1000, 1300, and 1500 rpm, the addition of 6–10% hydrogen enables the virtual HCNG engine to reach similar levels of torque and BSFC (brake specific fuel consumption) compared to same lambda condition of λCH4. For the relatively low 1000 rpm speed under conditions similar to those of the base engine, NOx formation is greater than base engine condition, while a similar NOx level can be maintained under the middle speed range (1300 and 1500 rpm) despite hydrogen addition. Upon addition of 6–10% hydrogen under the middle speed operation range, the target engine achieves performance and emission similar to those of the base engine.

Acoustic performance enhancement in a railway passenger carriage using hybrid ray-tracing and image-source method

Geometry of cabins, corridors, and materials used in railway passenger carriages can play important roles in acoustic performance inside the rail cars. In order to evaluate the noise level inside a rail car, a hybrid method based on the ray-tracing and image-source techniques is employed. A parametric model is constructed based on the field experiment performed in a typical coach cabin namely Fadak train in Iranian Railway. An Omni-directional sound source inside the passenger carriage is employed inside the cabin once for an unequipped cabin and once for operational one. Acoustic parameters such as reverberation time (T30), Center time (Ts), and the sound pressure level have been calculated and results are validated with experimental acoustic measurements. The model is experimentally calibrated and then acoustics performance of the passenger coach is enhanced by modifying the materials and absorption coefficients against two dominant sound sources in low to middle speed ranges. It is found the simple recommendation can remarkably enhance the acoustic performance over a broad range of frequencies.

The effectiveness of the inclusion of spatially oriented motor therapy in comprehensive rehabilitation programs for patients with spastic hemiparesis after stroke

The aim of the study — the evaluation of the effectiveness for restoring the functional abilities with Neurac method in patients undergoing stroke. Materials and methods. The study included 20 participants, they were divided into 2 groups, the first group — the patients who undergoing the stroke (main group): the main group of patients received a base standard rehabilitation program (kinesiotherapy, mechanotherapy on cyclic apparatгs, massage) and additional trainings in Redcord in Redsord system. The control group — a base standard rehabilitation program. The duration of the rehabilitation course was 14 days. Results and consideration. As a result of the study in both groups (main and control) as compared with the initial findings were better results of Berg Balance Test: 44,4±0,5 in the first group and 43,6±0,8 in the second group vs. 48±0,3 and 45,3±0,5 (р≤0,05). Although in patients of the first group after restoring treatment course with using method of Neurac method it was authentic lesser disturbance of everyday life activity: in estimating Bartel Index 86,9±0,5 vs. 80,1±0,7 (initial) (р≤0,05), what was significantly higher be comparison with control group results. In estimating 10 minutes walking test: 16,82±5,4 in the main group 2020 2 vs. 22,6±3,33 (initial) (р≥0,05), what was although significantly higher in comparison with the second group. By estimating walking on C-mill treadmill the middle speed in first and it second groups was 0,90±0,1 vs. 0,84±0,3 with 0,80±0,2 vs. 0,84±0,3 (ibitial) (р≥0,05). Conclusion: the obtained results point at the effectiveness of using Neurac method in restoring treatment programs for patient undergoing stroke for elevation of the stabilization of trunk, improvement of balance (in static, in functional movements, in walking), independence level in real life terms. An additional point is that this kind training can promote significantly positive influence on the patient’s motivation for actualization of active movement to improvement of the social and domestic adaptation, increase of motor and functional abilities.

A new model for the calculation of the bunker fuel speed–consumption relation

This paper investigates the relationship between bunker fuel consumption and the speed of container ships. Although there are different models existing in the literature and in the industry, they do not always seem to match the actual maritime conditions. The existing models work well in middle speed levels, but they fail at the low- and high-speed ends unless the parameters in the exponent of the function are changed. Besides the problem of missing a general formulation, the parameters seem to change with speed. Therefore, in this paper a new approach is introduced to illustrate the dependance between bunker fuel consumption and speed, and it is tested by formulating the exponent of the function variable. Stochastic criteria are used to compare the new generalized model with common models using real operating data.

Robust controller design for trajectory tracking of autonomous vehicle

In order to improve the stability and fault tolerance of the control system of the autonomous vehicle in the middle and low speed lane changing, a dual loop weighted trajectory tracking robust control system is designed. Firstly, the lateral displacement transfer function and yaw angle transfer function are derived by combining the mathematical model of trajectory planning and vehicle motion, and the proportion integral differential (PID) control parameters are calculated by mathematical derivation and transfer function reduction. Then, the influence of weighting coefficient on system stability and its determination method are studied by simulation. The results show that the dual-loop weighted control is feasible and effective, and it could provide a good fault tolerance, good control ability, good tracking effect, and small lateral displacement error and yaw angular velocity error for lane changing conditions in the medium and low speed.