Lower Gear Research Articles

Оцінка економічної ефективності оптимізації трансмісії пасажирських автобусів типу Setra S 417

The creation and implementation of technologies aimed at increasing fuel efficiency is becoming the focus of attention of car manufacturers. This may involve improving engines, using less dense materials to build cars, developing efficient transmissions, and implementing alternative energy sources. Changing the gear ratio of the main gear affects the force and speed of rotation of the car's wheels. When reducing the gear ratio (using a higher gear), the torque increases, but the speed of rotation of the wheels, which is used to overcome large obstacles or climb, decreases. Conversely, increasing the gear ratio (using a lower gear) decreases torque but increases wheel speed, resulting in higher speeds on flat surfaces. The effect of changing the gear ratio on fuel performance can be a bit complex. Basically, using a lower gear ratio (higher gear) can help save fuel at high speeds or when driving on level roads, because the engine can run more efficiently at lower rpm. However, in mountain conditions or when driving at low speeds, when more torque is needed, using a higher gear can result in more fuel consumption. The article proposes the reconstruction of the transmission, by replacing the gears of the main transmission, in order to change the gear ratio of the transmission of the Setra S 417 type passenger bus. The vehicle under study is operated at the "TRAVELBUS TERNOPIL" transport enterprise The traction-speed calculation of a bus with a unified transmission was carried out, the fuel-economical characteristic was calculated, and a reduction in the average consumption of fuel and lubricants was established. The effectiveness of the conducted unification was tested in different directions, and it was established that the greatest efficiency was achieved on the expressway. Such unification is not advisable on routes with mountainous terrain.

Gear Shifting in Biological Energy Transduction.

Confronted with thermodynamically adverse output processes, free-energy transducers may shift to lower gears, thereby reducing output per unit input. This option is well known for inanimate machines such as automobiles, but unappreciated in biology. The present study extends existing non-equilibrium thermodynamic principles to underpin biological gear shifting and identify possible mechanisms. It shows that gear shifting differs from altering the degree of coupling and that living systems may use it to optimize their performance: microbial growth is ultimately powered by the Gibbs energy of catabolism, which is partially transformed into Gibbs energy ('output force') in the ATP that is produced. If this output force is high, the cell may turn to a catabolic pathway with a lower ATP stoichiometry. Notwithstanding the reduced stoichiometry, the ATP synthesis flux may then actually increase as compared to that in a system without gear shift, in which growth might come to a halt. A 'variomatic' gear switching strategy should be optimal, explaining why organisms avail themselves of multiple catabolic pathways, as these enable them to shift gears when the growing gets tough.

Do Skills Naturally Transfer Between Multiport and Single-Port Robotic Platforms? A Comparative Study in a Simulated Environment.

Introduction and Objective: With introduction of the da Vinci single-port (SP) system, we evaluated which multiport (MP) robotic skills are naturally transferable to the SP platform. Methods: Three groups of urologists: Group 1 (5 inexperienced in MP and SP), Group 2 (5 experienced in MP without SP experience), and Group 3 (2 experienced in both MP and SP) were recruited to complete a validated urethrovesical anastomosis simulation using MP followed by SP robots. Performance was graded using both GEARS and RACE scales. Subjective cognitive load measurements (Surg-TLX and difficulty ratings [/20] of instrument collisions camera and EndoWrist movement) were collected. Results: GEARS and RACE scores for Groups 1 and 3 were maintained on switching from MP to SP (Group 3 scored significantly higher on both systems). Surg-TLX and difficulty scores were also maintained for both groups on switching from MP and SP except for a significant increase in SP camera movement (+7.2, p = 0.03) in Group 1 compared to Group 3 that maintained low scores on both. Group 2 demonstrated significant lower GEARS (-2.9, p = 0.047) and RACE (-5.1, p = 0.011) scores on SP vs MP. On subanalysis, GEARS subscores for force sensitivity and robotic control (-0.7, p = 0.04; -0.9, p = 0.02) and RACE subscores for needle entry, needle driving, and tissue approximation (-0.9, p = 0.01; -1.0, p = 0.02; -1.0, p < 0.01) significantly decreased. GEARS (depth perception, bimanual dexterity, and efficiency) and RACE subscores (needle positioning and suture placement) were maintained. All participants scored significantly lower in knot tying on the SP robot (-1.0, p = 0.03; -1.2, p = 0.02, respectively). Group 2 reported higher Surg-TLX (+13 pts, p = 0.015) and difficulty ratings on SP vs MP (+11.8, p < 0.01; +13.6, p < 0.01; +14 pts, p < 0.01). Conclusions: The partial skill transference across robots raises the question regarding SP-specific training for urologists proficient in MP. Novices maintained difficulty scores and cognitive load across platforms, suggesting that concurrent SP and MP training may be preferred.

Reduction of vehicle exhaust gas toxicity due to brake energy recovery

BACKGROUND: In recent years, fleet of vehicles in the Russian Federation is on a significant increase, that leads to considerably amplified emissions of toxic gases into the atmosphere. The share of toxic gas emissions from motor vehicles ranges from 65 to 70%. In order to reduce the toxic gas emissions into the atmosphere, electric vehicles have been introduced, but they have a number of disadvantages. These are a limited mileage before recharging and expensive batteries. Also, works on the use of hydrogen as a fuel for cars are conducted at an accelerated pace. However, the issue of a hydrogen fuel storage has not yet been worked out. At the same time, the used fleet of vehicles continues to poison the atmosphere.&#x0D; AIMS: Studying the braking energy recuperator for decreasing carbonic oxide CO in exhaust gases of the UAZ car.&#x0D; METHODS: The construction of a combined unit with a gas-hydraulic braking recuperator was developed, which is installed on a UAZ vehicle (RF Pat. No. 2193977). Comparative studies were carried out in accordance with GOST 33670-2015 and GOST 52033-2003.&#x0D; RESULTS: Results of comparative studies of the car showed that a minimum of CO emissions is observed in high gear, at a speed of 1825 m/s, and CO emissions significantly increase in lower gears. The recuperator eliminates this drawback due to the additional power transmission to the driving wheels.&#x0D; CONCLUSION. When a car starts in the urban cycle, there is a minimum of CO emissions with a recuperator, at the same time the car acceleration increases, that reduces the acceleration time and the distance by 3035%. A car with a recuperator on average consumed gasoline up to 15 l per 100 km, and this parameter of the production car was up to 17,5 l per 100 km of track. Due to the recuperator, CO emissions are reduced by 16%.

ON THE QUESTION OF CREATING A TRAILER BUS TRAIN

Hinged buses and bus trains are usually operated in large cities with heavy traffic. Therefore, the traction and speed properties of bus trains should be at the level of single buses. Among the 13 indicators of traction and speed properties that assess the dynamics of the road train, the most important are maximum speed, acceleration during acceleration, time and path of acceleration to maximum speed, acceleration time on the path of 400 and 1000 m. road trains. The A70132 diesel bus and the A701 electric bus were selected as the object of the study when working with the trailer. A comparative assessment of these buses on the indicators of traction and speed properties. It was found that the use of electric buses to create a bus train is problematic in view of the lack of traction in the area of high loads due to the acceleration of the bus. However, for a bus with diesel there is a significant reserve of traction in lower gears, due to the operation of the torque converter. The efficiency of using such a bus train when working on urban routes, where there is a limit on the maximum speed at 50 km / h. If the speed increases to 70 km / h, the use of a bus train consisting of a bus A70132 and a trailer with a total weight of 16,000 kg becomes inefficient. To increase the speed, it is necessary to either increase the power of the bus engine or activate the trailer.

Development of prediction methodology for CO2 emissions and fuel economy of light duty vehicle

Fuel economy prediction models usually require vehicle specifications such as a fuel consumption map which are not publicly available. Therefore, the present study proposed a new data analyzing procedure to predict CO2 emissions and fuel economy using on-road driving data without confidential specifications. Vehicle specifications such as gear ratios and vehicle mass which are provided in a service manual and driving data such as vehicle speed and CO2 emission were used to develop the prediction model. Instead of the fuel consumption map, linear equations for each gear between wheel power and CO2 emissions were used to predict CO2 emissions for various driving modes. Since higher gears exhaust less CO2 than lower gears (the seventh gear exhausted 24.4% less CO2 than the first gear), the accuracy of fuel economy prediction was improved by applying the equations for each gear stage. The accuracy of the prediction was verified by comparing it with measurement data. The comparisons showed that the equations for each gear can predict the fuel economy more accurately than one equation representing the entire gear. In worldwide harmonized light vehicles test cycle (WLTC) mode, the former had a maximum error of 6.1%, but the latter showed an error of 17.9%.

Design and Development of an Efficient Tri-Cycle

This report targets some improvement over existing design of paddle operated rickshaw and methodology for a new chassis design and structural rigidity analysis using software simulation (fusion360). The vehicle we have designed in this project is an improved model of existing conventional one. Improving the traditional design in terms of torque requirement and safety cum connivance of passengers is our goal. To improve and fix some of the design, structural and ergonomically flaws of this paddle operated three-wheeler vehicle, we have designed a whole new tubular chassis with a low-profile design to reduce the overall CG of the vehicle and cross members to enhance the structural rigidity. Then we have introduced rear axle wire powered mono disk brake, to improve stopping power without increasing the cost too much. We also have designed a 3 axle 4 sprocket system to deliver power from paddler to rear driving axle. By doing so we are trying to achieve a lower gear (sprocket) ratio with almost no chain de-railing. We have also included an optional gear system. For that we are using an already existing mechanism, Dog engagement gear (sprocket) system instead of conventional mountain bicycle type gear system to reduce cost and maintenance. Mathematical modeling of parts, assembly of the whole vehicle body and the analysis has been done in Autodesk Fusion360 software with academic license. Analysis was done through Finite Element Method using Fusion360.

BIOGAS AS AN ALTERNATIVE FUEL FOR AUTOMOTIVE TRANSPORT IN MOUNTAIN AREAS

The potential of low-calorie gases, in particular, biogas, which Ukrainian agriculture and industry produce in significant quantities, is almost never used here. The number of available domestic facilities for recycling such gases is scanty, although, in most developed countries, the significant number of such factories is operating. Landfill biogas is one of the promising energy sources, still, today, it is either emitted into the atmosphere, polluting it, or burned in flares. The use of biogas as fuel in automotive internal combustion engines is not sufficiently studied. However, the substitution of gasoline for biogas reduces engine power and increases fuel consumption. Especially this should be taken into account when operating vehicles in mountainous terrain under the conditions of reduced atmospheric pressure and temperature. Nevertheless, researching how mountain conditions can influence the performance of biogas-powered automobile engines is not given enough attention yet in Ukraine and in the world. Operation of cars on the mountain roads of the Carpathian region at the altitudes of 1000 ÷ 2000 m above sea level with rises and descents up to 12% and the section length up to 10 ÷ 15 km is difficult. The higher is the level of the terrain above the sea, the lower become the atmospheric pressure, air density and temperature, which deteriorates the filling of the car engine cylinders. The engine cooling rate decreases because of the air dilution and small speeds on steep slopes. Simultaneously, running engines on an excessively enriched fuel-air mixture and moving mainly in lower gears lead to engine overheating. Under the mountainous terrain conditions, Air to Boil temperature decreases. As we know the blend composition of biogas, it is possible to calculate its combustion value as well as the combustion value of the gas-air mixtures. Based on analytical research, we have plotted some graphs that reflect the dependence of the changes in the effective power and effective specific biogas consumption on the changes in ambient temperature and atmospheric pressure.

Clutch mechanism providing an increase in torque

A modernized vehicle clutch mechanism is proposed, which allows increasing the torque on the driven shaft, simplifying the design of the gearbox, eliminating the lower gear, simplifying the start and acceleration of the vehicle, and reducing the load on the friction clutch by reducing the transmitted power. Keywords: planetary differential, torque, gear ratio. khadeev@mail.ru

Design and Research of a New Type of Semi-Automatic Winding Seedling Packaging Machine

The current seedling packaging industry has the problems of cumbersome packaging process and low packaging efficiency. This phenomenon does not correspond to the high throughput and efficient packaging efficiency of seedling network marketing under the background of the existing Internet big data era, and the slow efficiency is seriously hindered. The rapid development of the seedling industry. In response to this problem, this paper made in-depth research and found that the seedling packaging occasions are mostly outdoor, there are problems such as power supply inconvenience. This paper designed a semi-automatic seedling packaging machine driven by artificial power, which is powered by human footsteps. The four-bar mechanism transmits the foot power, the hand wheel on the machine rotates to realize the clamping and fixing of the seedlings, and finally the gear train of the machine cooperates with the timing belt to provide the bidirectional winding power, and the upper and lower gears in the device drive the incomplete gear mechanism. Provides non-equal speed movement to achieve the winding and cutting of seedling wrap film. The Samsung wheel reversing mechanism can convert the winding method to realize the fast and complete winding of some seedlings (10cm-30cm), effectively improve the packaging efficiency, and enable the seedling network dealers to better adapt to the contemporary network business model. And provide technical reference for the research and design of similar products.

TRACTOR GEARBOX: RESEARCH OF SHIFTING GEARS’ PROCESSES

Introduction. The process of shifting gears under load is one of the most complex types of dynamic process in the transmissions of transport, road and construction vehicles. Currently, the existing calculation methods do not fully reflect the features of the engine and automated gearbox interaction by switching stages under load using more than two friction clutches at the same time. The paper discusses the method of calculating the dynamic characteristics of the gearbox with the simultaneous use of both two and four friction clutches by shifting gears under load with forward and reverse switching. The authors present the results of the dynamic characteristics of the theoretical study of the automated gearbox with frictional stages’ switching under load and without breaking the power flow.Materials and methods. The main method was based on a system approach to the dynamic processes study and on the modeling of the gearbox operation together with the internal combustion engine. The authors took into account the regulatory, speed and load engine characteristics, resistive torque variation, rate of pressure rise in clutches by shifting to higher and lower gears. The paper performed theoretical modeling of processes using the MATLab package and the Simulink application. Using the main blocks of this application, the authors created models of physical components: an internal combustion engine, friction clutches, gear reducers, elastic shafts, damping devices and tractor power transmission control systems.Results. As a result, the authors obtained calculated data of the dynamic processes, variations in speed and rotational torque on the gearbox shafts; the load on the engine by shifting gears at different values of the start and finish time in switching on and off the gearbox friction controls. The paper presented the relevant graphs of the processes.Discussion and conclusions. The developed method of calculating the dynamic characteristics of the gearbox allows simulating workflows by shifting to higher and lower gears. This method takes into account both the parameters of the gearbox design and of the control actions: the rate of switching on the friction clutches; the time intervals of overlapping the “on and off” clutches. Therefore, in relation to the considered gearbox, the authors determine the values of the optimal time control commands of the friction by shifting.Financial transparency: the authors have no financial interest in the presented materials or methods. There is no conflict of interest.

Digital twin of wheel tractor with automatic gearbox

This article describes the digital twin of power drive unit (engine and transmission) of 8-ton class wheel tractor with automatic gearbox. Detailed mathematical model of considered tractor power drive unit - engine with 16-speed automatic gearbox and friction shift of stages under load without breaking the power flow is given. The theoretical methods of research are based on the use of the MATLab package. With the help of fundamental package units, models of gearbox physical components are created: friction clutches, gears, shafts with the required properties, engine mathematical model, as well as model of the transmission control system. The calculation methods of the gearbox dynamic processes going on in the gear shifts using friction clutches is proposed. A feature of the mathematical model is consideration of the resistive torque, the rate of rise of switched on clutches friction torque, both during switching to the higher and lower gears. Mathematic simulation of tractor power drive unit operation under load was performed. The results of the completed calculations are presented. The possibility of using this digital model to simulate tractor operation during its main work operations is shown.

Математична модель логіки поведінки водія зразка автобронетанкової техніки при виборі швидкості руху з урахуванням дорожнього спектра опорів

It is well known that the mobility of armored vehicles, (hereinafter AV) - one of the main basic values in determining the possibility of performing combat missions units, which today is determined by the average speed in operational and tactical calculations. In order to increase mobility, scientists mainly improve the engine's specific power, control and suspension systems. Accuracy and correctness of the prediction of mobility is very important while planning operational-combat activities, carrying out special measures, because the accuracy and correctness of the performed operational-tactical calculations ultimately determines the correctness of the decision, and it is usually made in a limited time. This will finaly depend on whether the orders of the senior commanders, will be fulfilled in time. Calculating mobility, comanders usually do not take into account the most important thing - the realisation of the specified technical characteristics of the machines when driving in real conditions. The modulation of AV driver's actions in current conditions of combat service would allow to perform more accurate and fast calculations.The purpose of the article is to analyze the logic of driver's behavior of the AV when choosing the speed of movement with regard to the road spectrum resistance for its mathematical modeling and to use this model in assessing the mobility of armored vehicles during march units in conditions of situation complication. In our reseaching we analyzed works of previous scientists in the field of the driver's behavior logic armored vehicles in the selection of speed with regard to the road spectrum resistance and applied mathematical forecasting methods to determine the basic laws of speed distribution at low, medium and high gears. Also taking into account speed and gear selection. The logic of the driver's behavior is determined as a random value of the speed distribution function along the route. The analysis makes assumptions about the logic of the driver's behavior and the basic laws of speed distribution in low, medium and high gears. Namely: it is established that the logic of the driver's actions will be as follows: when switching to the necessary gear, the driver tries to maintain the maximum possible speed on it, non-accidental factors cause the need to reduce it. After overcoming random obstacles the driver again tries to up higher gear and maintain the speed. This distribution is possible for both low and medium gears, in which the specific thrust (dynamic factor) is sufficient for rapid acceleration, and only random factors lead to a decrease in speed. The laws of distribution (normal and equable) should be understood as averaged. The following considerations support the above distributions. At lower gears, when there is a sufficient supply of thrust, the acceleration is faster than at higher gears. Therefore, in lower gears the driver has to slow down and after overcoming obstacles, the operator can again quickly increase it to previous values or close to them. At higher gears, the speed increases much more slower, that is, the "Specific gravity" of the speed increases. This is confirmed by the fact that the nature of the density of distribution in low and medium gears will be closer to increasing, and in higher gear, to the normal law of distribution. As a result of the reseaching, it is advisable to develop a mathematical model of the logic of the driver behavior of armored vehicles when choosing the speed of movement, taking into account the road spectrum of resistance of armored vehicles in the unit's march in conditions of complication.

World Economic Prospects Monthly

Overview: Global economy in a lower gear in 2019–20 ▀ We still expect the pace of global GDP growth this year to be a little weaker than in 2018 and then to hold steady in 2020. Underlying financial conditions and an upturn in the manufacturing sector will be moderately supportive for growth but, with fiscal support set to wane and US‐China trade relations again looking more fractious, a rebound is unlikely and risks are still tilted to the downside. ▀ In response to the strong but deceptive US expansion in Q1, we now think that global GDP growth in the early part of this year was a little stronger than previously anticipated. In response, our 2019 global GDP growth forecast has been nudged up from 2.7% to 2.8%. However, this tweak to the profile has mechanically lowered our forecast for world growth in 2020 slightly from 2.9% to 2.8%. ▀ We still think that the recent soft growth patch is unlikely to morph into a substantial slowdown. Key to this is the ongoing resilience of the service sector – the global services PMI has been broadly flat since the start of this year. Meanwhile, the manufacturing data also seem to suggest that the sector has stabilised. Despite raising our end‐year Brent oil price forecast from $65pb to $73pb, inflation is set to rise only moderately. This, plus rising employment, bodes well for consumer spending. ▀ But any significant re‐acceleration looks a tall order. Beyond the short term, tight labour markets and labour supply weakness will constrain employment growth. And ongoing accommodative monetary policy is unlikely to trigger further sustained rises in asset prices. Fiscal policy support at a global level is waning and we are sceptical that Chinese policymakers will provide the world economy with a major fillip. ▀ Another fly in the ointment for growth is a potential re‐intensification of US‐China trade tensions; even if new tariffs do not materialise, they may undermine sentiment and investment. If President Trump implements his threat, this would probably push global GDP growth below the post‐crisis low of 2.6% in 2016.

Sex Differences in Performance and Pacing Strategies During Sprint Skiing.

Purpose: This study aimed to compare performance and pacing strategies between elite male and female cross-country skiers during a sprint competition on snow using the skating technique.Methods: Twenty male and 14 female skiers completed an individual time-trial prolog (TT) and three head-to-head races (quarter, semi, and final) on the same 1,572-m course, which was divided into flat, uphill and downhill sections. Section-specific speeds, choice of sub-technique (i.e., gear), cycle characteristics, heart rate and post-race blood lactate concentration were monitored. Power output was estimated for the different sections during the TT, while metabolic demand was estimated for two uphill camera sections and the final 50-m flat camera section.Results: Average speed during the four races was ∼12.5% faster for males than females (P < 0.001), while speeds on the flat, uphill and downhill sections were ∼11, 18, and 9% faster for the males than females (all P < 0.001 for terrain, sex, and interaction). Differences in uphill TT speed between the sexes were associated with different sub-technique preferences, with males using a higher gear more frequently than females (P < 0.05). The estimated metabolic demand relative to maximal oxygen uptake (O2max) was similar for both sexes during the two uphill camera sections (∼129% of O2max) and for the final 50-m flat section (∼153% of O2max). Relative power output during the TT was 18% higher for males compared to females (P < 0.001) and was highly variable along the course for both sexes (coefficient of variation [CV] between sections 4–9 was 53%), while the same variation in heart rate was low (CV was ∼3%). The head-to-head races were ∼2.4% faster than the TT for both sexes and most race winners (61%) were positioned first already after 30 m of the race. No sex differences were observed during any of the races for heart rate or blood lactate concentration.Conclusion: The average sex difference in sprint skiing performance was ∼12.5%, with varying differences for terrain-specific speeds. Moreover, females skied relatively slower uphill (at a lower gear) and thereby elicited more variation in their speed profiles compared to the males.

������������� ����̲���� ������������ ���������������� �������

Dynamic properties are characterized by the ability of vehicle to move according to a given law under the action of applied forces. Assessment of vehicle dynamic properties comes down to solving the 2nd (direct) problem of mechanics. In the designing vehicles, on the contrary, according to a given law of vehicle motion, the acting forces are determined, that is solving the 1st (direct) problem of mechanics. The standards for assessing the dynamic properties of vehicles are an expression of the requirements of the company, at this time stage, fixed in the relevant document (standard, technical conditions or regulations). The correct choice of the efficiency standards values, their terms of action helps to increase the competitiveness of vehicle in the world market. In the work of Podrygalo M.A. (assessment of the technical level by indicators of the vehicle dynamic properties) to assess the technical level of cars by indicators of dynamic properties, a new indicator has been introduced – the dynamic index . The analysis showed that, despite the variety of known dynamic properties indicators, there are no criteria in the literature that allow, at the design and testing stages, setting and evaluating the compliance of vehicles with modern requirements for dynamism. The purpose of the study is to increase the accuracy of predicting dynamic property indicators by determining the relationship between power density and vehicle dynamic index. It should be noted that in the work of Podrygalo M.. (assessment of the technical level by indicators of the vehicle dynamic properties) the initial acceleration is determined through the traction force to the driving wheels of vehicle when starting. As we know, it is possible to increase the initial vehicles acceleration when starting by increasing the gear ratio of the transmission in lower gear. This indicator is not related to engine power density. Therefore, in order to predict the increasing of dynamic properties, it is necessary to determine the relationship between power density and vehicle dynamic index Analyzing the dependence of dynamic index shows that it depends on the time of increasing effective engine power from zero to according to the hyperbolic law. Obviously, the value should not exceed unity. Otherwise, drive wheels will drag and the stability of vehicle translational movement will be violated. Thus, the rise time of the effective engine power from zero to its maximum value is a parameter that also determines vehicle dynamic properties. Conclusions – the obtained analytical expressions allow us to predict at the stage of preliminary design indicators of vehicles dynamic properties. Namely: the dependence of the dynamic index on the time of the increase in power to wheels from zero to .

Gear selection between techniques in freestyle cross-country skiing in athletes with intellectual impairment: A pilot study

Cross-country skiing is a fast-paced, a cognitively demanding, and a popular sport within international organizations including athletes with intellectual impairment (II); however, research on how the level of II affects skiing performance is limited. The aim of this exploratory study was to compare differences in the overall performance (segment time and race time) and gear selection between a sample of cross-country skiers with II ( n = 22) and a control group of skiers without II ( n = 12), during a competitive 10 km freestyle race. The groups were matched on training background and skiing level based on interviews with coaches and trainers. The independent samples t-test revealed a higher velocity in the first segment for the control group (6.10 ± 0.62 m/s) compared to the skiers with II (5.50 ± 0.56 m/s; p &lt; 0.05), but no significant differences in total race time between the groups. With respect to their ability to effectively select gears during the races, there was a significant difference between the groups, where the pattern was that skiers with II used a lower gear compared to the skiers without II and that pattern became even more apparent towards the second half of the race. These findings support the assumption that impaired cognitive function may constrain the ability to optimally select the appropriate gear in function of the characteristics of the skiing track, which is a key determinant of skiing performance.

ESTIMATION OF INERTIA MOMENT OF CAR ENGINE MOVING PARTS

To calculate the car dynamics, especially in urban conditions with frequent transitions to lower gears, the values of the inertia moment (MI) or the equivalent mass (EM) of the engine moving parts, brought to the crankshaft, are required. However, they are not given in the specifications, and the known methods of measurement are both too complex and laborious, or not suitable for some vehicle types. Goal. To create a method for estimation the engine MI, suitable for all types of vehicles and not requiring special equipment or excessive time, labor or expenses. The method proposed: to measure MI of driving wheels and transmission with known methods. To lift the car with jacks aid until the driving wheels come off the floor. To speed-up them by the engine repeatedly, recording the acceleration parameters, for example, by video filming the speedometer and tachometer readings. To remove the driving wheels and repeat the speeding-up in the same gear and, if possible, with the same fuel supply rate. Using the videorecords, to calculate the average acceleration in these modes and MI of the engine using the formulas given. Methodology and results of the method verification. According to GPS signals the speedometer of the car Honda Civic 2006 was calibrated. EM of driving wheels (2 × 10.49 kg) and transmission (5.4 kg) was measured by the known methods. 24 accelerations with wheels, followed by 20 ones without wheels were carried out. The interval of more or less stable acceleration (86...97 km/h) was common for both modes, where the average acceleration with the wheels was 2.6469 m/s2, without wheels –3.8792 m/s2. Then EM=39.664 kg and MI=0.1782 kg·m2 were calculated, which is in the range of known values for engines of similar volume. However, result variation is too large. The ways of method improving: to reduce and stabilize the acceleration rates, for example, putting an abut under the gas pedal; increase the number of samples. Scientific novelty: the method of estimating the car engine moment of inertia has been proposed and tested. Practical value: the method is suitable for all types of cars, does not require the use of high-speed roller stands or special equipment other than a jack and a phone with a video camera

Synthesis of energy­efficient acceleration control law of automobile

We have established the laws of change in the vehicle acceleration time at the existing step transmission of ICE, when implementing the total traction force, boundary for the drive wheels adhesion to the road, and during implementation of the proposed rational law for acceleration control. To model ICE speed characteristics, we applied the empirical dependence by S.R. Leyderman. The analytical expressions obtained allow us to implement such a change in vehicle acceleration depending on its speed that makes it possible to ensure maximum dynamism at minimal engine power consumption, taking into consideration a nonlinear change in external resistance. The maximum acceleration, which is possible to implement using the rational dynamic characteristic, can reach 7 m/s 2 . Based on the dependences obtained, it is possible to determine effective work of ICE required to accelerate a vehicle at different gears. An analysis of calculation results revealed that the transition from lower to higher gears is accompanied by a sharp decrease in engine energy expenditure required to accelerate the vehicle. It was established that for the case of hybrid vehicles, acceleration using the electric drive, rather than accelerating at lower gears of the mechanical drive, makes it possible to reduce energy losses by 20 % (for a four-cylinder internal combustion engine). Energy preservation is accomplished by reducing the fluctuation of traction force, as well as the possibility of a step-free change in motion speed.

Truck safety evaluation on Wyoming mountain passes

The Manual on Uniform Traffic Control Devices (MUTCD) for Streets and Highways recommends hill signs be placed in advance of downgrade descent of mountain passes. Mountain passes increase the risk of a runaway, or out of control trucks and so the advance warning signs inform the driver to take special precautions such as reducing speed or using lower gears during the descent. The Wyoming Department of Transportation has installed steep grade advance warning systems on Wyoming mountain passes. However, concerns for out of control trucks on the mountain passes persist. The objective of this study is to evaluate the safety effectiveness of steep grade advance warning signs for trucks on Wyoming mountain passes. The safety evaluation was carried out by implementing a zero-inflated negative binomial modeling technique for predicting truck crashes on mountain passes. The outcome was two models that showed the risk of runaway truck accidents were high at locations where either the grades were steep and long or the grades were long with multiple vertical curves. The analysis showed the current advance warning systems were not significantly impacting truck crash risks at the high risk locations. The study, therefore, recommends some improvements to the current advanced warning signs or implementing an improved Federal Highway Administration Grade Severity Rating System based warning system that will significantly improve truck safety at the hazardous locations. The study informs policy makers on the safety issues on Wyoming Mountain passes with regards to runaway trucks and makes recommendations for reducing the risk of runaway truck crashes on mountain passes.