Tyre modelling for an autonomous articulated wheel loader conducting a V-shape loading cycle simulation

The objective of this study was to evaluate the performance of 24 basic hydrodynamic mechanical power-split (HMPS) transmission designs effectively based on their torque multiplication capacities (TMCs) and efficiencies. Firstly, four schemes were preliminarily selected. Secondly, the matching between the four schemes and a reference wheel loader was considered, and an expression for the TMC was developed based on the traditional transmission and a second reference transmission. Thirdly, two performance metrics in terms of the TMC and efficiency – the average torque multiplication capacity (ATMC) and average efficiency – were defined to eliminate the couplings of four transmission parameters with the vehicle speed and speed ratio. Finally, the performances of the two best schemes and traditional hydrodynamic mechanical (HM) transmission were carefully compared. The results show that a transmission with power recirculation cannot present energy savings potential regardless of the ATMC, whereas a transmission with a power split can achieve an ATMC of 0.255, an average efficiency increment of 0.0143 in the short loading cycle, and a miniscule efficiency increment in the long loading cycle compared with the HM transmission.

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Wheel loader optimal transients in the short loading cycle

IFAC Proceedings Volumes ◽

10.3182/20140824-6-za-1003.02419 ◽

2014 ◽

Vol 47 (3) ◽

pp. 7917-7922 ◽

Cited By ~ 2

Author(s):

V. Nezhadali ◽

L. Eriksson

Keyword(s):

Wheel Loader ◽

Loading Cycle

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Features of the kinetics of cyclic elastoplastic deformation diagrams at dwells in cycles and superimposition of variable stresses on them

Industrial laboratory Diagnostics of materials ◽

10.26896/1028-6861-2020-86-12-46-53 ◽

2020 ◽

Vol 86 (12) ◽

pp. 46-53

Author(s):

M. M. Gadenin

Keyword(s):

Experimental Data ◽

Elastoplastic Deformation ◽

Low Cycle Fatigue ◽

Cycle Fatigue ◽

Loading Cycle ◽

Additional Variable ◽

Dynamic Creep ◽

Variable Stresses ◽

Kinetics Of ◽

Deformation Diagrams

The goal of the study is determination of the regularities of changes in cyclic strains and related deformation diagrams attributed to the existence of time dwells in the loading modes and imposition of additional variable stresses on them. Analysis of the obtained experimental data on the kinetics of cyclic elastoplastic deformation diagrams and their parameters revealed that in contrast to regular cyclic loading (equal in stresses), additional deformations of static and dynamic creep are developed. The results of the studys are especially relevant for assessing the cyclic strength of unique extremely loaded objects of technology, including nuclear power equipment, units of aviation and space systems, etc. The experiments were carried out on the samples of austenitic stainless steel under low-cycle loading and high temperatures of testing. Static and dynamic creep deformations arising under those loading conditions promote an increase in the range of cyclic plastic strain in each loading cycle and also stimulate an increase in the range of elastoplastic strain due to active cyclic deformation. At the same time the existence of dwells on extrema of stresses in cycles without imposition of additional variable stresses on them most strongly affects the growth of plastic strain ranges in cycles. Imposition of additional variable stresses on dwells also results in the development of creep strains, but their growth turns out to be somewhat less than in the presence of dwells without stresses imposed. The diagrams of cyclic deformation obtained in the experiments are approximated by power dependences, their kinetics being described in terms of the number of loading cycles using corresponding temperature-time functions. At the same time, it is shown that increase in the cyclic plastic deformation for cycles with dwells and imposition of additional variable stresses on them decreases low cycle fatigue life compared to regular loading without dwells at the same stress amplitudes, moreover, the higher the values of static and dynamic creep, the greater decrease in low-cycle fatigue life. This conclusion results from experimental data and analysis of conditions of damage accumulation for the considered forms of the loading cycle using the deformation criterion of reaching the limit state leading to fracture.

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Research on Protection Methods of Embedded Operating System Software Based on Hardware Compiler

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.443.556 ◽

2013 ◽

Vol 443 ◽

pp. 556-560

Author(s):

Gao Ming He

Keyword(s):

Operating System ◽

Practical Significance ◽

Embedded Operating System ◽

System Software ◽

Software Protection ◽

Performance Loss ◽

Cycle Simulation ◽

Protection Technology ◽

Program Flow ◽

High Level

This paper describes a system; CODESSEAL can provide protection and evaluation to system software. CODESSEAL was designed to protect embedded systems with sufficient expertise and resources to capture attack equipment and manipulator, not only to protect software but also to protect hardware. By using the reconfigurable hardware allows CODESSEAL to provide confidentiality, integrity of security services and a platform-independent program flow without having to redesign the processor. System uses software and data protection technology and designs cycle simulation methods for data analysis. Experimental results show that the protected instructions and data with a high level of safety can be realized a low, which in most cases the performance loss can be reduced to below 10%, so the research of software protection methods of the embedded operating system of hardware compiler has important practical significance.

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A New Method to Determine the Impact of Individual Field Quantities on Cycle-to-Cycle Variations in a Spark-Ignited Gas Engine

Energies ◽

10.3390/en14144136 ◽

2021 ◽

Vol 14 (14) ◽

pp. 4136

Author(s):

Clemens Gößnitzer ◽

Shawn Givler

Keyword(s):

Kinetic Energy ◽

Flow Field ◽

Turbulent Kinetic Energy ◽

Negative Impact ◽

Operating Conditions ◽

Engine Operation ◽

Gas Engine ◽

Cycle Simulation ◽

Simulation Results ◽

The Impact

Cycle-to-cycle variations (CCV) in spark-ignited (SI) engines impose performance limitations and in the extreme limit can lead to very strong, potentially damaging cycles. Thus, CCV force sub-optimal engine operating conditions. A deeper understanding of CCV is key to enabling control strategies, improving engine design and reducing the negative impact of CCV on engine operation. This paper presents a new simulation strategy which allows investigation of the impact of individual physical quantities (e.g., flow field or turbulence quantities) on CCV separately. As a first step, multi-cycle unsteady Reynolds-averaged Navier–Stokes (uRANS) computational fluid dynamics (CFD) simulations of a spark-ignited natural gas engine are performed. For each cycle, simulation results just prior to each spark timing are taken. Next, simulation results from different cycles are combined: one quantity, e.g., the flow field, is extracted from a snapshot of one given cycle, and all other quantities are taken from a snapshot from a different cycle. Such a combination yields a new snapshot. With the combined snapshot, the simulation is continued until the end of combustion. The results obtained with combined snapshots show that the velocity field seems to have the highest impact on CCV. Turbulence intensity, quantified by the turbulent kinetic energy and turbulent kinetic energy dissipation rate, has a similar value for all snapshots. Thus, their impact on CCV is small compared to the flow field. This novel methodology is very flexible and allows investigation of the sources of CCV which have been difficult to investigate in the past.

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Evaluation of the Performance of CMIP6 Models in Reproducing Rainfall Patterns over North Africa

Atmosphere ◽

10.3390/atmos12040475 ◽

2021 ◽

Vol 12 (4) ◽

pp. 475

Author(s):

Hassen Babaousmail ◽

Rongtao Hou ◽

Brian Ayugi ◽

Moses Ojara ◽

Hamida Ngoma ◽

...

Keyword(s):

North Africa ◽

Rainfall Variability ◽

Coupled Model ◽

Cumulative Distribution ◽

Climatic Research Unit ◽

Model Ensemble ◽

Empirical Cumulative Distribution Function ◽

Cycle Simulation ◽

Taylor Diagram ◽

Statistical Metrics

This study assesses the performance of historical rainfall data from the Coupled Model Intercomparison Project phase 6 (CMIP6) in reproducing the spatial and temporal rainfall variability over North Africa. Datasets from Climatic Research Unit (CRU) and Global Precipitation Climatology Centre (GPCC) are used as proxy to observational datasets to examine the capability of 15 CMIP6 models’ and their ensemble in simulating rainfall during 1951–2014. In addition, robust statistical metrics, empirical cumulative distribution function (ECDF), Taylor diagram (TD), and Taylor skill score (TSS) are utilized to assess models’ performance in reproducing annual and seasonal and monthly rainfall over the study domain. Results show that CMIP6 models satisfactorily reproduce mean annual climatology of dry/wet months. However, some models show a slight over/under estimation across dry/wet months. The models’ overall top ranking from all the performance analyses ranging from mean cycle simulation, trend analysis, inter-annual variability, ECDFs, and statistical metrics are as follows: EC-Earth3-Veg, UKESM1-0-LL, GFDL-CM4, NorESM2-LM, IPSL-CM6A-LR, and GFDL-ESM4. The mean model ensemble outperformed the individual CMIP6 models resulting in a TSS ratio (0.79). For future impact studies over the study domain, it is advisable to employ the multi-model ensemble of the best performing models.

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