Performing transient vibroacoustic analysis on a continuously variable transmission using a Vold-Kalman filter

Abstract: A continuously variable transmission (CVT) is a type of automatic transmission system that uses belts and pulleys to provide an infinite number of gear ratios. The system consists of two pulleys: a primary drive pulley and a secondary drive pulley, each with a fixed and a moving sheave. In snowmobiles, he primary pulley is connected to the crankshaft of a two-stroke engine, while the secondary pulley is connected to the track element. The use of a two-stroke combustion engine can cause torque fluctuations to propagate through the crankshaft to the CVT, resulting in excessive vibration and noise levels. To evaluate the vibroacoustic emissions of CVTs, alternative methods have been developed due to the limitations of road noise testing. One such method is to use an adaptive controller on a dynamometer to perform a repeatable acceleration phase, allowing for efficient and sophisticated acoustic analysis. Vold-Kalman order tracking (VKF-OT) with a phase-locked loop (PLL) is used to analyze the non-stationary periodic components of the noise generated by the CVT. This study conducted dynamometer experiments to identify the noise generated by the CVT during the acceleration phase. However, the analysis of the acoustic data can be difficult due to the lack of repeatability of the speed ramps during dynamometer tests. To solve this problem, post-processing methods have been proposed to synchronize the acoustic measurements taken at different speed ramps. The objective is to develop an adaptive approach to identify the prominent noise order, allowing a comparison of vibroacoustic performance between different CVT designs. Experimental results demonstrated the effectiveness of this experimental tool to analyze the attenuation of certain low order intensities during the acceleration phase.Résumé de la communication présentée lors du congrès international tenu conjointement par Canadian Society for Mechanical Engineering (CSME) et Computational Fluid Dynamics Society of Canada (CFD Canada), à l’Université de Sherbrooke (Québec), du 28 au 31 mai 2023

Order analysis method of a snowmobile CVT on a dynamic test bench

Les motoneiges sont équipées de moteurs à deux temps et de transmissions à variation continue (CVT), qui assurent une transmission de puissance optimale à la chenille de la motoneige en adaptant la vitesse de rotation des engrenages aux conditions de conduite. Cependant, lors des phases d’accélération constante, la CVT peut générer du bruit qui peut affecter le confort de conduite et la perception sonore du conducteur. Pour mieux analyser l’influence de la CVT sur l’émission acoustique du véhicule, une analyse vibroacoustique transitoire de la CVT est nécessaire. Pour ce faire, une méthode d’analyse d’ordre a été mise en place pour générer des conditions d’accélération susceptibles d’exciter la CVT. Ces conditions sont par la suite reproduites sur un banc de test moteur dynamique en utilisant une commande adaptative. Le suivi d’ordre est effectué en utilisant la méthode Vold- Kalman (VKF-OT) avec une boucle à verrouillage de phase (PLL), qui permet d’analyser les composantes de bruit périodique non stationnaire générées par la CVT. Des résultats expérimentaux ont été obtenus en utilisant deux CVT, l’une avec un amortisseur et l’autre sans. Ces résultats ont démontré l’efficacité de cette méthode pour analyser l’atténuation de certaines intensités d’ordre pendant la phase d’accélération.Abstract : Snowmobiles are equipped with two-stroke engines and continuously variable transmissions (CVT) that provide optimal power transmission to the snowmobile’s tracks by adapting the gear rotation speed to the driving conditions. However, during constant acceleration phases, the CVT may generate noise that can affect the driving comfort and the driver’s sound perception. To better analyze the inŕuence of the CVT on the vehicle’s acoustic emission, a transient vibro-acoustic analysis of the CVT is required. To do so, an order analysis method has been developed to generate acceleration conditions capable of exciting the CVT. These conditions are then reproduced on a dynamic engine test bench using adaptive control. Order tracking is performed using the Vold-Kalman method (VKFOT) with a phase-locked loop (PLL), which allows analyzing the non-stationary periodic noise components generated by the CVT. Experimental results were obtained using two CVTs, one with a damper and one without. These results demonstrated the effectiveness of this method in analyzing the attenuation of certain lower-order intensity during the acceleration phase

Weed Population Dynamics, Water Productivity and Grain Yield of Durum Wheat (Triticum durum L.) in No-Tillage and Conventional Tillage Systems

Introduction: Elimination or reduction of tillage in conservation agricultural systems has led to wide variations in germination, emergence, and growth of weeds and has caused variations in the density and diversity of weeds under such systems. Maintaining crop residues on the soil surface has many potential benefits in agricultural production systems; such as reducing water and wind erosions, increasing the soil organic matter content, improving the soil structure and sowing conditions, as well as a better weed management through allelopathy or physical interference provided by the crop residues. Crop residue and tillage system cause potential changes in the soil temperature and water content, which influence soil density, structure, moisture, as well as soil temperature and nutrients. Crop residues act as mulches and can effect on weed seed germination and seedling emergence. Therefore, the objectives of current study were to evaluate the effects of no-tillage systems on: (i) narrow- and broadleaved weed densities, (ii) crop yield and (iii) water productivity (WP). Materials and Methods: A two-year field study based on a split plot experiment in a randomized complete block design with four replications was carried out in Zahedshahr, Fars province, Iran (latitude 28˚44΄N, longitude 53˚48΄E, 1180 m altitude) during 2009-10 and 2010-11 growing seasons. The planting practices including moldboard plow, disk and leveler were practiced in conventional tillage plots and crop planting was performed using a drill seeder (made by Kohorasan Co., Iran). The no-tillage plots were directly planted without any soil disturbance and removing wheat residues of the last year using a direct planter machine (model Berteni, Argentina). Furrow irrigation was used at both systems and a water counter (model WD, size DN100) was applied to measure the amount of used water based on m3 ha-1. 1 x 1 m quadrates that were installed at the center of each plot. Crop density, narrow and broadleaved weed densities were recorded at 30 days after the beginning of crop emergence. Wheat grain yield was calculated at harvest time. Comparison of the means was conducted based on protected LSD (PLSD) at 0.05 significant levels. Results and Discussion: Tillage systems indicated a significant effect on wheat density. The average number of crop seedlings in no-tillage plots was 27 % higher than in the conventional tillage plots. Maintaining crop residues on the soil surface provided a better site for crop germination and emergence. The response to tillage system and year effects varied depending on the weed species. Results showed that the effect of tillage systems, year and their interactions were significant on the density of Lolium temulentum and Sinapis arvensis, while in the case of Phalaris minor and Hordeum spontaneum just the tillage regimen significantly influenced the weed density. L. temulentum and S. arvensis plants showed an almost similar pattern in their response to tillage systems and year effects. The density of these two species significantly decreased under no-tillage system compared with conventional tillage operations. Moreover, their densities in conventional tillage plots were significantly greater in the second year of the experiment than the first year. The lower seedling emergence of P. minor and H. spontaneum under no-tillage circumstances is not surprising, as crop residues prevent from reaching the light on the soil surface and the light requirement for germination of these species has been reported in several studies. The water productivity of the no-tillage plots was greater than of the conventional ones at both two years of the experiment. Preservation of wheat residues on the soil surface decreases soil temperature via shading and causes reduces the evaporation rate from the soil surface. Although there was no significant difference between wheat yields in the two growing seasons under conventional tillage environment, wheat yield in no-tillage plots was significantly greater in the second year of the experiment than that of the first year. Low weed densities and high WP were observed under no-tillage conditions, although the crop yield was greater in conventional tillage plots. It seems that this yield reduction in no-tillage plots is mostly due to greater C/N ratio in no-tillage plots than conventional tillage ones. Conclusion: According to the results, although wheat yield decreased under no-till system, increased water productivity, weed control and reduced cultivation costs might justify the adoption of no-tillage cropping systems by local farmers. Other principles of conservation agriculture including suitable crop rotation systems and planting cover crops must be incorporated into the no-till cropping system. As the occurrence of autumn rainfall is usual in these dry regions, employment of the stale seedbed might be another promising technique which controls early season weed species in no-tillage systems

Germination Ecology of Johnsongrass Seeds (Sorghum halepense (L.) PERS.)

Introduction Johnsongrass (Sorghum halepense (L.) PERS) is one of the most controversial and problematic weed. It is damaging at more than 30 different crops in 53 different countries. S. halepense (L.) is a perennial weed reproducing by seed and rhizome. Since it produces many seeds and rhizomes, it is difficult to control it. A weed germination plays an important role in attaining a prosper establishment in a typical agri-ecosystem; and this trend is adjusted with some environmental factors such as light, temperature, salinity, pH and soil moisture. If you consider the pattern of germination and emergence of weed species, you will able to provide comprehensive information to develop weed management strategies in the future. Thus, the purpose of current research has been to evaluate the breaking methods of the seed dormancy, effect of constant and alternative temperature, light, salinity and drought stress and burial depth on germination and seedling emergence of Johnsongrass. Materials and Methods Seeds of Johnsongrass (S. halepense L.) were collected in June 2013 from plants located at the research farmlands of the Agriculture research centre of Fars province in Zarghan town, Iran. Experimental treatments of Breaking Dormancy consist of six level of scarification with 95-98% acid sulfuric (4, 8, 15, 30, 45 and 60 minutes), in the other one, there were the soaked seeds in the water for 24, 48, 72 and 96 hours, and in the next group the seeds were heated in a 95- 98 boiling water for two and five minutes, and again in the next group, for 15, 30, 45 and 60 days, the seeds were chilled in 3 C, and in the last group, the seeds stored in 3 and 12 months after harvest comparing to control treatment. A number of 25 seeds were transferred to incubators to identify a suitable temperature and light regime for subsequent experiments of germination and determine under alternative day/night temperatures (15/5, 20/10, 30/15 and 35/20 C) and constant temperature day/night (5, 10, 15, 20, 25, 30, 35, 40 and 45 C) in both light/dark and dark regimes. The salt and osmotic potentials were applied in -1, -3, -5, -7, -9, -11 levels and control treatment in order to survey the stress of salt, drought on seed germination and to compare both stress on it. NaCl was applied in the Vant Hoff method to influence salt stress and also PEG 6000 was applied in the Michel methods to affect osmotic potential. In the burial depth experiment, a number of 30 seeds, for 30 days, were laid in the depth of 0, 0.5, 1, 2, 3, 4, 6, 8 cm in plastic vases with 15 cm diameters. All experiments were conducted twice in the form of randomized complete-block design with four replications. Each replication was arranged on a different shelf of growth chamber and considered as a single block in the laboratory experiments. The data of the replicated experiments were pooled for analysis, as the time interaction and treatment was absolutely meaningless. A functional three-parameter logistic model Was fitted to the germination values (%) obtained at different concentrations of NaCl or osmotic potential. Also, a sigmoidal decay curve was fitted to show the seedling emergence (%) values at different burial depths. Results and Discussion Seed germination was influenced significantly on different treatments of breaking dormancy (Fig 1). Sulfuric acid treatments showed significant difference rather than control treatment. In 30 and 45 min sulfuric acid scarification, germination was recorded more than 95 %. Based on the achieved results it is very probable that the hard seed prevents germination and this issue causes the weed remains stable in seed bank. Germination percentage was not affected by light regime and temperature interaction (both in constant and alternative) (Fig 2a and 2b), the influence of different temperatures on the feature was significant (Fig 2a). The same germination has been seen in all temperatures (both light and light/ dark regime) in all temperature, The more temperature increased, the seed germination increased too. In both regime, at 25/15, 30/20 and 35/25 C (day/night), germination was recorded more than 95 % (Fig 2a). The maximum and the minimum germination percentage of Johnsongrass in light/ dark regime, were accorded in alternative temperature in 30/25 C (99.5%) and 15/5 C (35.5 %) respectively. In constant and alternative temperatures, the germination was similar. In the constant range of 25-45 C temperatures, the feature was occurred more than 90 % (Fig 3a). The maximum and the minimum germination percentage, in light/ dark regime, were recorded in 25 C (99%) and 5 C (0%) respectively (Fig 3a). The experiment on light revealed Johnsongrass seeds was not influential to light, therefore it wasn't photoblastic species and the germination percentage will not exceed through light. The germination percentage could not be decreased by light as a major factor. Accordingly it is reported that Johnsongrass seed was not photoblastic and the light regime had the slightest effect on the number of seed germination. As the matter of fact the temperature has greater importance comparing with light. The deeper the seedling planted, the fewer emergences were accorded. The emergence at the surface of the soil (zero depth) was 83.33% and in depth of 3 cm it was 100%. The minimum emergence for 18.35%, devoted to depth of 8 cm (Fig 5). With an increase in five cm burial-depth, the seedling emergence decreased for 81.65 %. According to the fitted sigmoid model, the depth which caused a decrease for the maximum 50% seedling emergence calculated 5.60 cm. The results showed that weed seedling emergence was limited in depth of 6 cm and over. The decrease in seedling emergence may be linked to seed energy with increasing buried depths. Agronomic practices causing a decrease in seed germination and an increase seed death is able to help the weed management. Our study model proved that 5.60 cm was the depth in which 50% the maximum emergence decreased (Fig 5) and therefore, tillage more than 6 cm could help reducing germination and emergence of this species. Conclusions Based on the above results, we come to conclusion that Johnsongrass seed is able to tolerate a variety of environmental circumstances and as soon as providing a suitable condition such as temperature, in particular, it is capable to improve beyond 90% of germination. Salinity and drought stress play no important role in germination. Although, the more increase in depth, the less seedling emergence happens. Consequently one of the best methods of managing this weed is to till the field over 6 cm