Variable Traction Research Articles

Tractor linkage loads with adjustable characteristics

Efficient use of agricultural tractors is largely determined by the operating modes of its power units. Taking into account the variable nature of external loads, it is necessary to provide structural devices in the tractor, which smooth out changes in hook load, thus reducing the negative impact of external conditions on the operation of its power plant. The present paper is devoted to the design of a tractor attachment with variable characteristics. The methods of studying the variable traction force are analyzed on the output parameters of the technological process, as well as on the power and economic indicators of the power unit. Force analysis of the proposed attachment device is carried out and formulas are obtained to determine the forces and moments at the characteristic points of the device. The paper is of interest to engineers and technicians involved in the creation of promising design schemes for tractor tractors of various operational purposes.

Evaluation of the coupling forces of the spindle roller with the drive belts to improve the cotton harvester

This article investigates the optimization of coupling forces between spindle rollers and drive belts in vertical spindle cotton harvesters, aiming to enhance harvesting efficiency and completeness. Traditional vertical spindle machines face limitations in collecting cotton from bushes, primarily due to inferior spindle-belt interactions compared to horizontal spindle counterparts. Challenges arise from variable traction capacity in friction drives, exacerbated by diminished contact angles between rollers and conventional V-belts. To address these issues, experiments were conducted comparing traditional V-belts with ribbed belts, demonstrating superior traction capabilities of ribbed belts. A novel roller design, coupled with ribbed belts, showcased significantly higher clamping forces, indicating enhanced performance potential. The experimental setup involved a custom-built bench for measuring adhesion forces, providing empirical data supporting the superiority of ribbed belts. The findings suggest that adopting ribbed belts with appropriate roller designs can significantly improve traction and operational stability in spindle drive systems. This research contributes to advancing mechanical engineering knowledge, offering insights into optimizing friction drive systems for enhanced performance and productivity in cotton harvesting machinery and other industrial applications.

Research of the plowing quality with a unit based on a modular traction-transportation vehicle

The implementation of modular traction-transportation vehicles (MTTV-80) will allow, to a large extent, to solve problems related to the range of tractors. MTTV-80 consists of an energy-rich tractor (energy module - EM) and a trolley with an active drive of its movers (technological module - TM). Such a vehicle has a variable nominal traction force, as it makes it possible to use it both as part of the EM + TM and as a separate energy module, and therefore has high production versatility and technological adaptability. The creation of MTTV-80 allows it to be used both as vehicles and as devices on the basis of which it is possible to create machine-tractor units (MTU) for agricultural enterprises. The variable traction force of these devices will allow to significantly increase the annual workload of tractors in farms. According to the results of the research, it was found that the longitudinal-vertical oscillations of the MTTV-80 energy module of the plowing MTU, created on the basis of the MTTV-80, have a much smaller effect on the longitudinal-vertical oscillations of the plow. As a result, this allows the unit based on a modular device to plow with less variation in its depth. The frequency of the plowing depth exceeding the accepted agrotechnical tolerance ∆ = ±2 cm for the MTTV-80-based MTU is 2.7 times lower than that of the tractor-based MTU.

T-piece Traction Removal for Buried Bumper Syndrome

Percutaneous endoscopic gastrostomy (PEG) has become the standard nutrition access with well-established procedural and long-term safety data. Yet, buried bumper syndrome (BBS) remains a major concern and complicates up to 5% of PEGs. Albeit poorly standardized, endoscopic management is possible in most internal disc migrations with variable traction- or dissection-based techniques available. Most advanced BBS stages > Cyrany stage 2 call for incision of hyperplastic tissue overgrowth due to insufficient traction forces for nondissection extraction.[1]

Research on Dynamic Modeling Measurement and Control of Cable Traction Devices for Electro-Optical Unmanned Systems

In order to realize the high-precision variable direction cable control of the electro-optical unmanned system in non-electromagnetic remote control, a cable traction device measurement and control with characteristics of variable direction traction, rapid installation, and lightweight portability were proposed. Fan-shaped connect rod mechanism and U-shaped groove fixed pulley group were added to it, which can realize multi-direction traction without derailment on the basis of the cable limit and alleviate the cable fracture caused by mechanical wear. Introducing Euler transformation and analyzing the dynamics of the cable, the whole operation process, and the tension detection model was established. A Kalman Filter traction planning method was proposed to solve the problems of inertia delay and emergency stop of the unmanned vehicles after a sudden direction change. In order to verify the effectiveness, an experimental platform for the cable traction system of a 50kg wheeled and 150kg tracked unmanned system was built for simulation and experimental testing. The results show that the cable system has good dynamic variable traction, which can meet the multi-terrain control ability of an electro-optical unmanned system in a complex field environment.

Chemo-Mechanical Factors That Limit Cellular Force Generation

Cellular traction forces that are dependent on actin-myosin activity are necessary for numerous developmental and physiological processes. As traction force emerges as a promising cancer biomarker there is a growing need to understand force generation in response to chemical and mechanical cues. Our goal is to present a unified modeling framework that integrates actin-myosin activity, substrate stiffness, integrin bond type, and adhesion complex dynamics to explain how force develops under specific conditions. Our simulation results show that substrate stiffness and number of myosin motors contribute to the maximum actin-myosin forces that can be generated but do not solely control the force transmitted by the cells to the surface, i.e., the traction force. The kinetics of the bonds between the cell and the substrate plays an equally important role. Overall, we find that while the cell can generate large actin-myosin forces in individual stress fibers (> 300 pN), the maximum force transmitted to the surface per cell-substrate attachment only reaches a fraction of these values (approx. 50 pN). Traction stress, the sum of forces transferred by all cell-substrate attachments in a unit area, is biphasic or sigmoidal with increasing substrate stiffness depending on the number of active myosin motors generating forces. Finally, we conclude that adhesions < 1 μm2 generate widely variable traction forces and that impulse, the magnitude and duration of a force generating event, is a key limiting factor in traction stress.

Effect of lumbar traction on discogenic low back pain using variable forces.

To determine the effect of variable traction forces on discogenic low back pain. The experimental study was conducted at the Department of Physical Medicine and Rehabilitation at the Combined Military Hospital, Okara, Pakistan, from July to December 2018, and comprised patients of low back pain who were randomised into group 1 treated with high-force lumbar traction, hot pack and lumbar stabilisation exercises, and group 2 treated with low-force lumbar traction, hot pack and lumbar stabilisation exercises. There were a 3 sessions per week for 3 weeks for a total of 9 sessions. Modified Oswestry disability index and visual analogue scale were used to measure outcomes. Data was analysed using SPSS 20. Of the 30 patients, there were 15(50%) in each of the two groups. There were 18(60%) females and 12(40%) males, with an overall mean age of 30±5.5 years. Also 18(60%) subjects were obese on the basis of body mass index.There was significant improvement in pain in both groups (p<0.05), while disability scores in group 1 showed more improvement compared to group 2 (p<0.05). Young age was significantly associated with better results (p<0.05). Use of variable force lumbar traction improved pain in discogenic low back pain, while high-force lumbar traction also reduced functional disability.

A METHODOLOGY TO SELECT ASYNCHRONOUS TRACTION ELECTRIC DRIVE FOR INNOVATIVE METRO ROLLING STOCK

The paper deals with the justification of the need to use an asynchronous traction electric drive on the metro rolling stock. The advantages of using an asynchronous traction electric drive in comparison with a DC commutator motor drive are formulated. The characteristics of modern innovative metro rolling stock with asynchronous traction electric drive of domestic and foreign production are analyzed. Aspects of the choice of a variable frequency asynchronous traction electric drive for innovative rolling stock are formulated and the existing typical algorithm of such choice is given. The main reasons for the irrational choice of traction asynchronous electric drive for the metro rolling stock are considered and the consequences of such a choice are analyzed. It is proposed to improve the methodology for selecting a variable frequency traction asynchronous electric drive for the metro rolling stock in terms of such an important operational factor as the specific cost of electrical energy for traction. The rational parameters of the variable frequency asynchronous traction electric drive according to the proposed procedure for the specified characteristics of the metro rolling stock are specified. The reserves of energy savings for the given conditions due to the introduction of an asynchronous traction electric drive with rational parameters on the innovative rolling stock are determined. It is established that the efficiency factor of the asynchronous traction motor significantly affects the specific electric energy consumption for the metro rolling stock traction and operating costs.

МОДЕЛИРОВАНИЕ ПРОЦЕССА ДЕФОРМИРОВАНИЯ И ДВИЖЕНИЯ ПОЧВЫ В ЗОНЕ ВОЗДЕЙСТВИЯ ГЛУБОКОРЫХЛИТЕЛЯ

Analysis of available literature shows that nowadays an advanced scheme of the technological process and new designs of operating elements of the subsoiler working in conditions of deblocked cutting has been developed. The aim is to improve the quality and to reduce the energy consumption by machines and equipment during deep tillage. However, at present, the theory of vibrations and strength loading of the units of subsoiler, when its operating elements interact with soil, is not sufficiently developed. This paper highlights the issues regarding the modeling of soil during interaction with operating elements of a subsoiler. Based on the use of the Rakhmatulin model of a compressible plastic medium and the Ilyushin «flat cross-section hypotheses», the equation of the soil motion is formulated, and the dynamic phenomena occurring in the soil and subsoiler elements under variable traction are described. The calculation results are obtained in the Maple-8 programming environment using the methods of solid mechanics and soil mechanics.

Optimal compensation control of railway co‐phase traction power supply integrated with renewable energy based on NSGA‐II

In railway traction power supply, co-phase system with hybrid power quality conditioner (HPQC) is capable of tackling the power quality issues caused by single-phase traction loads. To further reduce the overall carbon emissions in railway systems, this paper considers to integrate the renewable energy with railway power supply, which however leads to a more complicated system to model, design and control. This paper first investigates its modelling aspect. To reduce the operating capacity of HPQC while addressing the power unbalance, optimal design of the compensation scheme for co-phase system is formulated as a multi-objective optimization problem which is then solved by the nondominated sorting genetic algorithm-II (NSGA-II). To eliminate the impact of errors arising from imperfect predictions of the loads and renewable power, a hybrid optimal compensation control is proposed, yielding full and optimal compensations. Comprehensive simulation studies, considering three operation modes covering variable traction loads, renewable and regenerative braking power, are conducted. The simulation results confirm the validity of the proposed optimal compensation scheme, achieving an average of more than 20% reduction in HPQC capacity compared to the full compensation scheme. Meanwhile, the power quality requirement is satisfied, even in the presence of real-time prediction errors.

A partial compensation scheme for MMC-based railway cophase power supply

Abstract This paper presents a partial compensation scheme for V/v transformer cophase traction power supply in high-speed railway systems. The scheme compensates variable traction load current, and controls the current phase at the secondary side of the V/v transformer for power factor correction and negative sequence current reduction. To achieve this, the grid side current phase angles are optimized while satisfying the grid code on the power factor and voltage unbalance limits. The optimized phase angles are then used to design control references under varying load conditions. The compensation control action is updated regularly based on real-time measurements of the traction load, and the required currents are controlled by a 25-level single-phase back-to-back MMC power conditioner to achieve the compensation target. Static and dynamic load compensation performances are verified based on the simulation studies.

Modeling and Compensation for Dead-Time Effect in High Power IGBT/IGCT Converters with SHE-PWM Modulation

Research on applying selective harmonic elimination pulse width modulation (SHE-PWM) to high power converters has drawn tremendous interest, due to the advantages of low switching frequency and high output harmonic performance. In the fields of high power converters such as variable speed traction motor drives and static synchronous compensators (STATCOM), the adoption of high voltage but slow speed semiconductor devices, i.e., IGBT/IGCT, results in a longer dead time of several microseconds, which leads to a motor vibration in the former case or the distortion of grid current in the latter case. This paper analyzes in detail the mechanism of the dead-time effect on 3-level SHE-PWM with different operating conditions considered. For the first time, a general mathematical model describing the relationship between the dead time and harmonic distribution of SHE-PWM wave is established. Based on which an open-loop compensation method by inserting a margin time into the effective switching angles is proposed. Furthermore, a closed-loop controller that implements online adaptive adjustment of the margin time is designed in case of a variable frequency application. The effectiveness of the proposed method in different scenarios is verified through simulation results.

Design method of a power management strategy for variable battery capacities range-extended electric vehicles to improve energy efficiency and cost-effectiveness

Energy management strategy and battery capacity are the primary factors for the energy efficiency of range-extended electric buses (REEBs). To improve the energy efficiency of REEBs developed by Tsinghua University, an optimal design method of global optimization-based strategy is investigated. It is real-time and adaptive to variable traction battery capacities of series REEBs. For simulation, the physical model of REEB and key components are established. The optimal strategy is first extracted by the power split ratio (PSR) from REEB simulation result with dynamic program (DP) algorithm. The power distribution map is obtained by series simulations for variable battery capacity options. The control law for developing optimal strategy are achieved by cluster regression for power distribution data. To verify the effect of the proposed energy management strategy, characteristics of powertrain, energy efficiency, operating cost, and computing time are ultimately analyzed. Simulation results show that the energy efficiency of the global optimization-based strategy presented in this paper is similar to that of the DP strategy. Therefore, the overall energy efficiency can be significantly improved compared with that of the CDCS strategy, and operating costs can be substantially reduced. The feasibility of candidate control strategies is thereby assessed via the employment of variable parameters.

INCREASE IN EFFICIENCY OF THE CYCLIC DRIVING OF WELLS IN SOIL

Processing methods of a cyclic driving of wells with a diameter over 300 mm by methods of vibro-impact pushing and combined with partial consolidation and excavation of soil on the basis of use of pneumo-percussive mashines (pneumatic bore-hole driver) are given in work. The results of researches received with use of the ground intake devices physical models have allowed to establish characteristics of change of force of resistance to the return transportation of the equipment with the taken soil core in process of his removal from a face. Analytical expressions for engineering calculation of the winch tractive force are received. Technical characteristics of the created number of the winches of scraper type working at the uniform energy carrier with shock cars – compressed air are given.The schematic diagram winch with hybrid pneumatic drive, the having variable traction and high-speed characteristic is offered at a limited expense of the energy carrier which realization of a design at vibroshock breakdown and a combined method allows to reduce time of a production cycle of formation of wells and to increase productivity of driving works. A schematic diagram of a winch with a hybrid pneumatic drive is proposed, which has variable traction and speed characteristics with a limited energy carrier consumption, the implementation of the design which in vibro-impact pushing and combined method allows to reduce time of process of formation of wells and improve the performance of the tunneling works.

Dynamic external traction combined with internal fixation for treatment of comminuted intra-articular fractures of the base of the thumb proximal phalanx

Objective To document the efficacy of our modified dynamic external traction system that is applied concomitantly with internal fixation for comminuted fractures at the base of thumb proximal phalanx. Methods From March 2009 to July 2014, 7 cases of comminuted fractures at the base of thumb proximal phalanx with metacarpophalangeal(MP) joint involvement (AO type C fractures) were treated with open or close reduction and internal fixation. Meanwhile a dynamic external traction system was applied. Postoperative exercise started early.Range of motion of the MP joint, pinch strength and postoperative complications were evaluated. Results Postoperative follow-up period ranged from 13 to 32 months, with an average of 18 months. The mean plaster splint immobilization time was 7.7 days (range, 3 to 14 days). The external fixator was removed at 4.3 weeks on average (range, 4 to 6 weeks). The internal fixation hardware removal time was 7.2 weeks postoperatively on average (range, 6 to 9 weeks). All the patients were able to return to their original jobs. The average active range of motion for the MP joint of the thumb was 8.6° (range, 5° to 10°) extension and 42.4° (range, 35° to 50°) flexion. Mean pinch strength was 89% of that of the contralateral side. According to the upper extremity functional evaluation criteria issued by the Hand Surgery Society of the Chinese Medical Association, the results were rated as excellent in 5 cases and good in 2 cases. Conclusion Dynamic external traction system combined with internal fixation can provide reliable fracture fixation and allow early mobilization of the MP joint. The variable traction force can effectively maintain joint stability during movement and reduce adhesion and contracture of the joint. Key words: Thumb; Finger phalanges; Intra-articular fractures; Dynamic traction

Studying Characteristics of Traction Induction Motors for Variable-Speed Mine Electric Locomotive

The analysis of torque-speed characteristics of induction motors has been carried out in order to choose the base design for variable speed traction electric drives of underground mine electric locomotives. For constant dimensions of active part of series-produced electric motors the influence of the diverse conductivity’s materials for manufacturing the squirrel-cage rotor on speed-torque and speed-current characteristics. The designs are compared according to speed-up dynamics, power indexes and key design features of the studied electric motors.

A Cooperative Train Control Model for Energy Saving

Increasing attention is being paid to energy efficiency in subway systems to reduce operational cost and carbon emissions. Optimization of the driving strategy and efficient utilization of regenerative energy are two effective methods to reduce the energy consumption for electric subway systems. Based on a common scenario that an accelerating train can reuse the regenerative energy from a braking train on the opposite track, this paper proposes a cooperative train control model to minimize the practical energy consumption, i.e., the difference between traction energy and the reused regenerative energy. First, we design a numerical algorithm to calculate the optimal driving strategy with the given trip time, in which the variable traction force, braking force, speed limits, and gradients are considered. Then, a cooperative train control model is formulated to adjust the departure time of the accelerating train for reducing the practical energy consumption during the trip by efficiently using the regenerative energy of the braking train. Furthermore, a bisection method is presented to solve the optimal departure time for an accelerating train. Finally, the optimal driving strategy is obtained for the accelerating train with the optimal departure time. Case studies based on the Yizhuang Line, Beijing Subway, China, are presented to illustrate the effectiveness of the proposed approach on energy saving.

Sustainability Aspects of Energy Conversion in Modern High-Speed Trains with Traction Induction Motors

Some aspects are illustrated of energy conversion processes during the operation of electric railway vehicles with traction induction motors, in order to support transport systems’ sustainability. Increasing efforts are being expended to enhance the sustainability of transportation technologies and systems. Since electric drive systems are used with variable voltage variable frequency (VVVF) inverters and traction induction motors, these machines with appropriate controls can realize both traction and electric braking regimes for electric traction vehicles. In line with this idea, this paper addresses the operation sustainability of electric railway vehicles highlighting the chain of interactions among the main electric equipment on an electrically driven railway system supplied from an a.c. contact line: The contact line-side converter, the machine-side converter and the traction induction motor. The paper supports the findings that electric traction drive systems using induction motors fed by network-side converters and VVVF inverters enhance the sustainable operation of railway trains.

A New Design of Variable Traction Tracked System

This paper discussed the possibility of deploying the proposed Variable Geometry Tracked Vehicle (VGTV) in our first robotic based prototype called REC-01. REC-01 is being developed as a miniature scouting and search &amp; rescue all-terrain robotic vehicle. Its comparatively small size and mass limit its power capacity and navigational capabilities for larger obstacles. The VGTV is a unique concept used to overcome these shortcomings. The main part of this paper is to discuss the mechanical efficiency of the tracked systems in some specific field conditions and compare the results with the conventional tracked propulsion. The outcomes of the first prototype are also briefly discussed in this paper.

Results of modeling of process of acceleration of tractoranalogue «Belarus 3022 DV» with hydrovolumetricmechanical transmission

The improvement of performance of a wheeled tractor during technological operations by reducing energy losses when slipping, and the effect of the hydrovolumetric-mechanical transmission on slipping are urgent issues of great practical importance. That is why there is a need to study and analyze the process of acceleration of a wheeled tractor «Belarus 3022 DV» with hydrovolumetric-mechanical transmission. The article determined the impact of laws of variation of regulation characteristics of the hydrovolumetric transmission, and of hydraulic motors working volumes on key parameters of transmission and slipping of tractor’s wheels with variable traction force on a hook and acceleration on traction range. There is a comparative analysis of the slipping of wheels of the tractor «Belarus 3022 DV» with hydrovolumetric-mechanical transmission with a tractor that has equivalent parameters, and mechanical transmission. The article presents the changes in engine power, in the operating pressure drop in the hydrovolumetric transmission, in the slipping of front wheels, in the efficiency of transmission, in the traction power on the hook on the operating volume of hydraulic motors and speed of the tractor with various laws of variation of regulation characteristics of hydrovolumetric transmission. In addition, the article discusses and analyzes the acceleration of tractor during transport operations.