Start Of Ramp Research Articles

Ramp Start and Speed Control of Self-Driving Commercial Vehicles under Ramp and Vehicle Load Uncertainty

In order to improve the performance of self-driving commercial vehicles for half-hill starting, a ramp control strategy based on the back-slip speed corresponding to the parking moment is proposed. Firstly, the longitudinal dynamics model of the vehicle is established, the force of the vehicle on the ramp is analyzed, and the rear slip speed of the vehicle is matched with the parking moment, and finally the target speed is tracked based on the sliding-mode controller, and in order to validate the validity of the method, two comparative algorithms of the pure PI controller and the proportional gain controller based on the back-sliding speed corresponding to the resting moment are designed for comparative experiments, and the data results show that the control strategy based on the resting moment corresponding to the backsliding speed of the sliding mode ramp start control strategy can stably complete the ramp start under different weights and different slopes, and greatly reduce the backsliding distance of the vehicle.

VIRTUAL MODEL OF THE SYSTEM "INDUCTION MOTOR - SOFTSTARTER WITH TWO CONTROLLED PHASES"

One of the most commonly used start methods of induction motors is starting by gradually increasing the supply voltage. At the same time, softstarters based on thyristors or triacs are used, which are cheaper in comparison with frequency inverters based on IGBT - transistors. In turn, the disadvantage of this method of starting with significant reduction of the starting torque, so the possibility of using such starters for various executive mechanisms requires careful research. In the presence of a limitation of power source power, especially in wartime conditions, the problem of limitation of starting currents, especially in the case of using starters with two adjustable phases, is actual. To take into account the multiplicity of starting currents for different types of mechanisms, a mathematical model of the system " induction motor - softstarter with two controlled phases" was created. The model differs from the known ones by the possibility of limiting the power of the power supply network, the appearance of the mechanical characteristics of the executive mechanism and the starting moment at voltage ramp start mode. Transient processes in relative units for the possibility of estimating the multiplicity of starting currents to determine the required power of the autonomous power source are presented. To assess the adequacy of the mathematical model, a research stand with measuring of motor winding currents using a current transformer and a microprocessor device with an oscillography function was created. In the work, a comparative analysis of the results of modeling and experimental studies on a physical model is carried out, herewith the discrepancy of the results did not exceed 10%. It was determined that when using a soft-start device with two adjustable phases, even with small voltages, the current multiplicity is quite high and requires the use of a power source of greater power, but less than in the case of direct start. Formulated conclusions based on research results and recommendations for further reduction of starting currents.

Characterization of ventilatory efficiency during cardiopulmonary exercise testing in healthy athletes.

Ventilatory efficiency (⁠V˙E/V˙CO2) during exercise is defined as the ratio of minute ventilation (⁠V˙E) and carbon dioxide output (⁠V˙CO2) and reflects matching of alveolar ventilation and pulmonary perfusion as well as ventilatory drive.1 Abnormally high V˙E/V˙CO2 is important diagnostically and prognostically in the setting of cardiopulmonary disease.1 Current clinical guidelines propose a total slope (⁠V˙E/V˙CO2-total) < 30 as normal,1 with higher cutoffs (⁠V˙E/V˙CO2-total < 34) providing prognostic value in specific diseases.2,3 While some recommend measurement of V˙E/V˙CO2-total slope over only the linear portion of the curve from the start of exercise to the second ventilatory threshold (VT2, also known as the respiratory compensation point),4,5V˙E/V˙CO2-total is often measured over the entirety of the exercise effort given robust prognostic data in heart failure using this technique.2,3,6 Normative values for V˙E/V˙CO2 have been derived from general population cohorts,4,6 but remain limited in athletes.7,8 By virtue of high motivation and cardiorespiratory fitness, athletes are capable of sustaining a graded exercise effort well beyond the VT2 after which V˙E increases relative to V˙CO2 in late exercise even in the absence of cardiopulmonary disease. Resultant elevation in V˙E/V˙CO2-total when measured through the end of exercise may confound assessment for pathology. The primary aims of this study were to define athlete-specific normative values for V˙E/V˙CO2 and to assess the performance of existing cutoffs and predictive equations for V˙E/V˙CO2 in athletes. This prospective cohort study included a select group of athletes who underwent effort-limited clinically indicated cardiopulmonary exercise testing (CPET) on either the treadmill or upright cycle ergometer from 2011 to 2021 in the Massachusetts General Hospital Cardiovascular Performance Program. As previously described, rigorous exclusion criteria were used to generate a cohort free from clinically evident cardiopulmonary disease.9 Endurance sports were defined as distance running, cycling, rowing, triathlon, and/or swimming. V˙E/V˙CO2-total was defined as the V˙E vs. V˙CO2 slope from the ramp start to peak exercise, V˙E/V˙CO2-start-VT1 as the slope from the ramp start to the first ventilatory threshold (VT1), and V˙E/V˙CO2-Nadir as the lowest continuous 30 s average V˙E/V˙CO2 ratio during exercise. Peak V˙O2 (pV˙O2) was defined as the highest oxygen uptake, averaged over 30 s, during the last minute of exercise. Gas exchange data were analysed using a mid-5-of-7 averaging algorithm (i.e. the moving average of five breaths excluding the lowest and highest). Categorical variables are presented as n (%) and continuous variables are presented as mean [standard deviation (SD)]. Linear regression was used to assess the relationship between V˙E/V˙CO2 and other variables. The performance of existing V˙E/V˙CO2 prediction equations was assessed by regressing measured on predicted V˙E/V˙CO2 and by Bland–Altman analysis. The upper limit of normal (ULN) was defined as >90th percentile for predicted V˙E/V˙CO2-total,6 and predicted V˙E/V˙CO2-Nadir +(1.66 × SD).4 Statistical analyses were performed using R (R Core Team, Vienna, Austria, 2022). This study was approved by the Massachusetts General Brigham Institutional Review Board. In 521 athletes (age = 38 ± 15 years, 33% female, 91% white), exercise was completed on the treadmill in 292 (56%) and cycle ergometer in 229 (44%). Most participants were endurance athletes (n = 330, 63%), with the remaining participating in mixed/other sports (n = 191, 37%). Table 1 presents V˙E/V˙CO2 and pV˙O2stratified by age and sex. V˙E/V˙CO2-total exceeded the guideline-recommended cutoff of 30 in 66/172 (38%) females and 106/349 (30%) males and exceeded the prognostic threshold of 34 in 30/172 (17%) females and 40/349 (11%) males. In the total population, V˙E/V˙CO2 exceeded the prognostic threshold of 34 in 70/521 (13%) athletes using V˙E/V˙CO2-total, 10/521 (1.9%) using V˙E/V˙CO2-start-VT1, and 2/521 (0.4%) using V˙E/V˙CO2-Nadir. Of the 70 athletes with V˙E/V˙CO2-total >34, only 8/70 (11.4%) had V˙E/V˙CO2-start-VT1 > 34 and 2/70 (2.9%) had V˙E/V˙CO2-Nadir >34 (Figure 1).

Wind power ramp event detection using a multi-parameter segmentation algorithm

The variable nature of wind power and the associated ramp events poses a number of operational challenges to grid operators, especially under high penetration of wind energy. These challenges typically relate to system stability, frequency control and dispatch. The adverse impacts of wind power ramps can be mitigated in practice through optimal scheduling and dispatch of flexible reserves and rapid response ancillary services. This, however, requires appropriate ramp detection algorithms, together with accurate ramp forecasting. This paper proposes a novel multi-parameter segmentation algorithm for the detection of wind power ramps. Ramp detection results are presented for a utility-scale wind farm, and the performance of the proposed algorithm is compared with existing algorithms, including the L1-ramp detect with sliding window and the optimized swinging door algorithm. The results show that the proposed algorithm is superior, particularly with reference to criteria such as ramp detection accuracy, computational expedience and ramp start- and end-point accuracy.

The Research and Development of Motor Cooling Control System Based on Electronic Parking Brake Test Bench

When Electronic Parking Brake test bench validates the function of ramp start, Electronic Parking Brake (Simplified as EPB) control motor has been blocked state, the motor heat is large. Followed putting forward the performance required by the motor cooling system, and the cooling control system scheme and the control strategy of intelligent electronic pump motor by building a mathematical module about cooling system of EPB motor, this paper designs and develops the electronic water pump motor controller, including the efficient control on the pump, and the communication with the main controller, which is based on CAN bus and SAE J1939 and optimizes the hardware and software of motor controller so that the pump efficiency may reach 32%. The product-level design, shown by a large number of performances testing, is achieved.

Smashed Death Case Related to Traffic Accident

Traffic on roads may consist of pedestrians, ridden or herded animals, vehicles, streetcars and other conveyances, either singly or together, while using the public way for purposes of travel. A car accident is a road traffic incident that usually involves one road vehicle colliding with another vehicle or other road user, animal, or a stationary roadside object, and may result in injury, property damage, and possibly death. Our case was 62 years old man. In witness statement, when they were walking on walkway a lorry swerved to the walkway. He saw smashed body of his friend between the lorry and wall. Driver says that because of break fade from the ramp start he hit from behind of a car and then bumped into the wall in his statement. In the report of expert witness break fade were used up. The body of this man lost its unity. Because of advanced degree of disruption, age, sex, weight, height and other identification parameters couldn’t be evaluated properly. The body was break into 5 main pieces. Other small pieces were determined weighting from the 10g to the 250g, totally 15kg.blood and urine couldn’t be found. The reason of death was reported as general body trauma. As a result, vehicle maintenance and checking vehicles carrying passenger or cargo are very important. We want to emphasize also importance of crime scene investigation with this case.

The influence of transition onset location on the performance of shock control bumps

AbstractIn order to investigate the robustness of three dimensional bumps on shock control for natural laminar-flow wings, the impact of transition onset location on the overall performance of the shock control device was studied. For a ramp bump, a moderate ramp start angle θr =4° was found to effectively fix the location of the leading leg of the shock lambda, decreasing chord-wise movement in the main shock position resulting from variations in transition onset location. With increasing transition onset length from xtrans =0% chord to 45% chord, little influence was found regarding the overall performance of the shock control device but a down-stream movement of the secondary leg of the shock lambda in a range about 3% chord was observed. Change in the boundary-layer displacement thickness due to varying transition onset locations was identified as the primary mechanism responsible for this secondary shock leg movement.

A 77-GHz Cooperative Radar System Based on Multi-Channel FMCW Stations for Local Positioning Applications

In this paper, a radar system for local positioning applications is presented. The system consists of frequency modulated continuous-wave (FMCW) stations operating in W-band that are loosely coupled using time-delayed ramp start signals. A centralized signal processing approach allows to relax the required synchronization accuracy between the stations and further leads to a cancellation of phase noise and phase distortions caused by imperfect FMCW ramps. All stations are equipped with an antenna array and multiple receivers. Thus, a signal processing approach is developed in this work that combines the positive effects from the centralized processing with the information from the antenna array in a digital-beamforming based approach to improve the multipath robustness of the overall system. The developed theory is confirmed in measurements carried out with a prototype system consisting of two stations. Various measurements in multipath environments confirm the improved robustness leading to a worst-case root-mean-square position error of 15 mm under strong multipath conditions which were simulated inside an anechoic chamber.

Analysis of a Cylindrical Specimen Heated by an Impinging Hot Hydrogen Jet

A computational conjugate heat transfer methodology was developed, as a first step towards an efficient and accurate multiphysics, thermo-fluid computational methodology to predict environments for hypothetical solid-core, nuclear thermal engine thrust chamber and components. A solid conduction heat transfer procedure was implemented onto a pressure-based, multidimensional, finite-volume, turbulent, chemically reacting, thermally radiating, and unstructured grid computational fluid dynamics formulation. The conjugate heat transfer of a cylindrical material specimen heated by an impinging hot hydrogen jet inside an enclosed test fixture was simulated and analyzed. The solid conduction heat transfer procedure was anchored with a standard solid heat transfer code. Transient analyses were then performed with ,variable thermal conductivities representing three composites of a material utilized as flow element in a legacy engine test. It was found that material thermal conductivity strongly influences the transient heat conduction characteristics. In addition, it was observed that high thermal gradient occur inside the cylindrical specimen during an impulsive or a 10 s ramp start sequence, but not during steady-state operations.

Simulation of dynamic fusimotor effects in the discharge frequency of Ia afferents by prestretching the muscle spindle.

The discharge patterns of primary muscle spindle afferents from the tibial anterior muscle of the cat were recorded under a ramp-and-hold stretch of constant amplitude (7 mm) and stretch rates varying between 1 and 50 mm/s. With seven Ia fibers, the discharge patterns were recorded under various dynamic gamma stimulation frequencies of between 10 and 120 stimuli per second. With 26 passive spindle fibers of the type known as bag1 Ia fibers, the discharge patterns were obtained under progressively increasing prestretch of the muscle. From each discharge pattern the following discharge frequencies were read: the initial activity (the discharge frequency before the start of ramp stretching), the peak dynamic discharge (the discharge frequency at the end of the dynamic phase of stretching), the maximum static value (MSt; the discharge frequency at the beginning of the static phase of stretching), and the final static value (the discharge frequency at the end of the 3rd s of the plateau phase). These four discharge frequency values were plotted against MSt, in separate diagrams for the Ia fibers under dynamic gamma stimulation and for the bag1 Ia fibers. The relationship between the four discharge frequency values and the MSt turned out to be the same-or much the same-for both groups of Ia fibers. This means that the two groups of Ia fibers produced (more or less) identical discharge patterns in response to the ramp-and-hold stretch. In addition, where Ia fibers of the two groups had the same MSt, their dynamic and static responses were determined. Under these circumstances no difference was found in respect to their stretch properties between Ia fibers of dynamically gamma-activated spindles and bag1 Ia fibers of passive spindles. In the Discussion, the high degree of similarity in the behavior of the two groups of Ia fibers is explained in terms of the mechanical properties of intrafusal bag1 fibers, which render it likely that in passive intrafusal bag1 fibers stretch activation will evoke the same mechanical behavior as dynamic gamma activation.