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Low speed autonomous shuttles emulating SAE Level L4 automated driving using human driver assisted autonomy have been operating in geo-fenced areas in several cities in the US and the rest of the world. These autonomous vehicles (AV) are operated by small to mid-sized technology companies that do not have the resources of automotive OEMs for carrying out exhaustive, comprehensive testing of their AV technology solutions before public road deployment. Due to the low speed of operation and hence not operating on roads containing highways, the base vehicles of these AV shuttles are not required to go through rigorous certification tests. The way the driver assisted AV technology is tested and allowed for public road deployment is continuously evolving but is not standardized and shows differences between the different states where these vehicles operate. Currently, AVs and AV shuttles deployed on public roads are using these deployments for testing and improving their technology. However, this is not the right approach. Safe and extensive testing in a lab and controlled test environment including Model-in-the-Loop (MiL), Hardware-in-the-Loop (HiL) and Autonomous-Vehicle-in-the-Loop (AViL) testing should be the prerequisite to such public road deployments. This paper presents three dimensional virtual modeling of an AV shuttle deployment site and simulation testing in this virtual environment. We have two deployment sites in Columbus of these AV shuttles through the Department of Transportation funded Smart City Challenge project named Smart Columbus. The Linden residential area AV shuttle deployment site of Smart Columbus is used as the specific example for illustrating the AV testing method proposed in this paper.

Crashes at highway rail grade crossings (HRGCs) are often involved with fatalities due to the momentum of a train. This study collected nine years (2010–2018) of fatal HRGC crashes from the Fatality Analysis Reporting System (FARS) to perform the analysis. The Taxicab Correspondence Analysis (TCA) was applied to this dataset. This method identified several patterns that trigger HRGC-related fatal crashes. The findings indicate that fatal crashes involving multiple fatalities are often highly associated with alcohol-influenced drivers, poor lighting conditions, and inclement weather. The fatal crash that occurs during the daylight with the uninfluenced driver is less likely to involve more than one fatality. The results also recognized the combinations of vehicle type and speed are associated with fatal crashes at rail grade crossings. The relatively low-speed limit crossings and larger utility vehicles are more likely to be associated with fatal crashes because large vehicles require a longer time to cross railroads at a low speed. The relatively high-speed limit crossing and smaller or lighter vehicles, especially the motorcycle, are highly associated with fatal crashes.

During braking with ABS (Anti-Lock Brake System), low braking initial speed causes to build-up and reduce brake pressure in longer time period due to extending application time of brake pressure and response time of solenoid valve. Also, the decision about speed and acceleration variations of wheel becomes very difficult due to weak speed signals arising from low speed. This results in lower braking torque than needed on the wheels. Therefore, effects of weak wheel speed signal become more pronounced in critical road conditions due to sudden changes in wheel speed. In this study, the effects of these problems occurring in low speed were investigated on both control and braking performance of ABS under critical road conditions. For this, ABS tests were carried out for low and high speeds on four different road types, which include slippery, wet and mu-jump tests (from wet to slippery and from slippery to wet). In this way, the results were compared to both vehicle speed and road type. The test results show that the low speed worsens braking stability, control and braking performance of ABS, regardless of road conditions. For this reason, it is proposed that ABS control algorithm must be divided in two parts as low and high speed control. (C) 2021 Karabuk University. Publishing services by Elsevier B.V.

The use of gas fuels for marine two-stroke low-speed internal combustion engines is considered by the International Maritime Organization as the main tool for implementing the program adopted in 2018 to reduce greenhouse gas emissions by half by 2050 compared to 2008. In this regard, the world's leading manufacturers of this type of engines are actively engaged in research and development work aimed at developing, designing, manufacturing and putting them into operation. In this class of engines, there are a number of limitations that do not allow the existing experience of converting four-stroke marine engines to gas fuel to be applied to them. In this regard, each manufacturer develops its own approaches to solving this problem. As a result, two fundamentally different approaches were outlined - this is the supply of gas fuel directly to the working cylinder at the beginning and at the end of the compression stroke. Each of these methods has its own advantages and disadvantages. Earlier, the authors showed that in addition to the already implemented technical solutions, other approaches can be used related to the supply of gas fuel into the working cylinder under a pressure of 4.0...6.0 MPa, which allow combining the advantages of both methods implemented in practice and significantly reduce their inherent disadvantages. In particular, reducing the residence time of the gas-air mixture in the working cylinder of the engine during the compression stroke is an effective method of combating knocking combustion that occurs in low-pressure engines. In turn, this time depends on the pressure under which the gas fuel is supplied to the gas supply module and on the characteristics of its outflow through the flow path of this device. This article is devoted to the study of the influence of the design features of the flow path on the formation of the trajectories of gas fuel movement and the parameters of its outflow from the gas module to the working cylinder under conditions of changing back pressure.

Low‐speed and high‐torque direct‐drive permanent‐magnet motors have found wide applications primarily due to their outstanding performance characteristics. The special applications of these motors demand high reliability against the motor drive system, that is, the power system should have a certain level of fault tolerance. Therefore, the fault‐tolerant motor drive system has been the focus of research all over the world. Many fault‐tolerant motors can only deal with the open‐circuit fault of the winding or drive, and their capability of fault tolerance is substantially limited. When in operation, the short‐circuit fault caused by the ageing of winding insulation may result in more serious hazards than the open circuit in the winding. Such serious faults should be tolerated by the fault‐tolerant system. Moreover, the simpler maintenance or shutdown repair upon completion of fault‐tolerant operation of large‐sized fault‐tolerant motors should also be considered. Therefore, a permanent‐magnet fault‐tolerant motor with module combination stator (MCS‐PMFTSM) and unequal span winding is proposed. By changing the winding structure of the conventional motor the modular operation of the whole motor is achieved, which not only provides the motor with a high fault tolerance capacity but also reduces the downtime during repair and maintenance. In this work, the structure and operating principles of the MCS‐PMFTSM are described followed by the evaluation of the operation performances of the MCS‐PMFTSM under different fault conditions and various control strategies. The fault‐tolerant capacity of this new machine is then analysed, and the prototype is tested with a power of 12 kW and a rated speed of 100 r/min. Both theoretical analysis and test results demonstrate the outstanding operation performance and high fault tolerance of the motor.

Low-speed pre-ignition (LSPI) remains one of the challenges of Direct Injection (DI) Spark Ignition (SI) engines due to its potential to induce a heavy knock. Several mechanisms have been identified in the literature as plausible causes for LSPI. The physical and chemical properties of lubricant oils play a role on some of these causes. The present work aims at getting an independent procedure to determine the proneness of lubricant oils to ignite. To this end, the ignition delay (ID) of different oil formulations is experimentally determined in a constant-pressure flow facility through two different optical techniques: Schlieren and OH* chemiluminescence imaging. The investigation explores the effect of base-stock formulation, oil specification quality level, different additive types content, aging, and oxidation on oil reactivity for several thermodynamic conditions. Differences in ignition delay were found among base stocks, correlating with the American Petroleum Institute (API) group classification. However, no significant differences were found among additive packages previously reported to yield different LSPI occurrences. Hence, differences in reactivity among lubricating oil formulations are not the determining factor explaining their different LSPI occurrences in an engine. Similarly, specific lubricant additive content, aging, and oxidation do not importantly modify the measured ignition delay.

In this paper, the scientific basis for designing wind power plants (WPP) with low-speed synchronous generators on permanent magnets (SGPM) is understood as a system of scientific knowledge that forms the theoretical basis for the practice of designing a complex object, such as WPP consisting of interconnected equipment and structures designed to convert wind energy into electrical energy. Currently, the development of advanced WPP designs is receiving increased attention around the world. For example, in the Russian Federation, a promising direction is the creation of Autonomous WPP with low-speed medium- and low- power SGPMs that have the maximum range of applications by type of activity and climate zones throughout the territory. However, engineering approaches to the design of individual components of the WPP indicate the difficulties of developing a scientifically based methodology for optimizing the parameters of the WPP as a whole taking into account the mutual influence of individual components on each other. At the same time, the methodology for optimizing the parameters of WPP is understood as a tool for the scientific basis of design, which takes into account quality indicators and optimality criteria, energy and technical characteristics, as well as design stages with the results of preliminary and verification calculations. For the stage of verification calculations of VEU parameters, the scientific basis of design is determined by the construction of mathematical models and their research using application software packages for PCs, while for the stage of preliminary calculations, the development of analytical methods of analysis is important. This article discusses the scientific basis for designing wind turbines at the stage of preliminary calculations, formulated the problem of optimizing the parameters of low-speed WPP, proposed equations for the relationship of design parameters with the energy performance of wind turbines, providing the maximum efficiency of synchronous generators, taking into account the specified technical conditions

The paper presents a methodology for finding the ratio of design and operating factors in relation to low-speed compressor stages. The technique is based on the simplex method, which allows you to choose from a database created on the basis of a well-known technique for calculating the working processes of low-speed compressor stages, the best solution for specific search criteria taking into account their importance. The technique is implemented in Microsoft Excel, an example of the implementation of the technique with five criteria is presented: temperature, flow rate, indicator efficiency, weight and overall dimensions.

With high number of vehicles on road and without any proper lane management and lack of concentration during parking the amount of collision has increased drastically. Generally, crashes are avoided but in some unfortunate case when the situation is unavoidable the crash is most likely to be taken by the bumpers of the vehicle. The bumpers of a vehicle are provided in front and back both sides of the vehicle. “The key role of the bumper is to provide the safety to the expensive parts like engine, radiator, cooling mechanism, headlights etc. The bumper also helps in the energy absorption during high and low speed impacts. Generally, the slow speed impact condition is not considered while designing of a bumper, and the amount of energy absorption is not considered for slow speed. “In this paper, low speed impact analysis of a car bumper is performed for the central impact and corner impact. Five different design variations are performed using finite element analysis. Parameters like the shape of the bumper and thickness are varied and impact condition is taken into consideration. The fifth design that is “Effect of increased thickness for modified profile” is found to be best in energy absorption during impact. From the analysis performed it is observed that the damage of the vehicle can be reduced by providing lining of suitable stiffness to the front metal bumper.

An optimized lubrication condition of the crosshead bearing in low-speed marine diesel engines is pivotal to its prolonged service life, because the bearing oscillates at a low speed and the direction of the high load is always downward. Theoretical studies on the tribology of the crosshead bearing are very limited, with existing studies ignoring the effects of connecting rod inertia. Herein, a new multi-body tribo-dynamic model for the engine is presented by coupling the dynamics models of the connecting rod, piston assembly, and crosshead assembly with the mixed lubrication models of the multiple lubricated joints including the crosshead bearing. Based on this new multi-body tribo-dynamic model, the bearing load, journal center trajectories, friction torque, and minimum oil film thickness were calculated and compared with those based on the simplified method used in the previous literatures. The results show that due to the connecting rod inertia, the bearing load in the transverse direction calculated by the simplified algorithm is different from that calculated by the tribo-dynamic model proposed in this study. Compared with the results based on the previous simplified method, the inertia of the connecting rod reduces the friction torque of the bearing, especially at the end of the upward stroke.

Train-track-bridge dynamic tests were conducted on the Shanghai Lingang Medium and Low Speed Maglev Test Line. A newly developed levitation bogie with mid-set air spring was used on the test train....

Motorcycles are a primary mode of daily transportation in many developing countries, especially in towns and cities. The increased traffic congestion constrains the average speed of the motorcycle, causing stability and safety concerns for the riders. A controller that assists the riders can improve this scenario. This paper presents a new controller developed using an experimental study that improves the low-speed stability of a motorcycle. The experiments were conducted on a motorcycle with the riders of three experience levels: beginner, intermediate and expert. The input parameters: steering angle and steering torque; the output parameters: roll angle, yaw angle, roll rate and yaw rate were measured. Critical input and output parameters were identified statistically from the experimental measurements and used for the controller modelled in Simulink. The controller model was co-simulated with a multi-body dynamics model of the motorcycle. The co-simulation results showed the controller developed herein stabilises the motorcycle model at low speeds.

Maritime transport has made great contributions to the prosperity and development of the world economy. And the low-speed marine diesel engine has played an important role. However, with the aggravation of energy shortage and marine pollution, the development of diesel engines is facing unprecedented pressure. It is therefore urgent to improve the performance of fuel system of diesel engine. In this study, a simulation model of fuel system for a low-speed diesel engine was established. And the accuracy of the model was validated because of the good agreement between the experimental data and simulation results of system pressure characteristics. Based on the verified model, the influence of key parameters on system pressure characteristics was examined. The results show that the mass of pressure amplification piston and flow capacity of pressure amplification control valve have slightly influence on the pressure characteristics of the system. And the impact of diameter of big and small end of pressure amplification piston is more obvious than the first two, for they change the pressure amplification ratio. The diameter of high-pressure fuel tube is the most influential factor to system pressure characteristics. The reason is that the pressure accumulative effect is strengthened as it increases, which leads to a dramatical change happened to the movement of pressure amplification piston and the propagation of pressure waves.

Based on the one-dimensional field theory for linear induction motor (LIM), the analytical model of two adjacent series motors was built, then the relationships between spacing and traction, curren...

The feasibility of the calculation model and calculation methods is verified by engine bench test and visual rapid compression machine (RCM) test as reported in this paper. Using AVL software FIRE, the processes of low speed preignition (LSPI) and super knock triggered by the oil particles have been studied by numerical analysis of downsized turbocharged direct injection (DI) engines with different proportions of ethanol-gasoline blended fuel and different operating conditions (1200 r·min−1, 1600 r·min−1). The results show that the E10 and E20 fuel engines produce super knock successively; with the increase of the ethanol proportion, even if the LSPI phenomenon (1200 r·min−1) still occurs and leads to the subsequent knock process, the pressure rise amplitude is obviously reduced, and no super knock phenomenon occurs at the time when the ethanol proportion reaches 30%; there is no LSPI phenomenon in the engine after the blending rate is above 50%. The overall conclusion is that there must be LSPI before the super knock in ethanol-gasoline blended fuel downsized turbocharged DI engines, but the LSPI not always lead to super knock. With the increase of ethanol proportion, even if the LSPI occurs in the engine cylinder, it only causes regular knock.

Vehicular Ad Hoc Networks (VANETs) is an important field of study nowadays. VANETs attracts attention of vehicles communication researcher due to its potential to improve vehicle road safety, enhance traffic and travel efficiency, and provide convenience and comfort for passengers and drivers. Due to the fact that modern life, especially when travelling in vehicles, is in need for high throughput, this paper investigates the Block Error Rate (BLER) and throughput performance of vehicle-to-Infrastructure (V2I) communication between LTE node and vehicles in urban-low environment using two different stochastic channel model used urban-low areas because urban-low speed areas is the common road situation for a large number of users require connection with LTE node. Vehicle-to-Infrastructure - Urban (V2I-U) is used in urban areas and Vehicle-to-Infrastructure – Urban Small intersection (V2I-US) channel model, used as a reference model, has the largest maximum excess delay near to the 3GPP Extended Vehicular A (EVA) channel model. The performed simulation is done at low speed, 40 km/h in 10 MHz bandwidth for the 2.6 GHz carrier frequency. Results show that V2I-U meets the highest value in the throughput that reaches 20 Mbps as those obtained from the EVA one without huge effect on the BLER. This result can be attributed to the fact of using Line-of-Sight (LoS) which leads to less dispersion of the frequency and less doppler frequency shift.

Pilot‐ignited high‐pressure direct‐injection (HPDI) natural gas engines have drawn much attention since being proposed, as these engines can maintain high performance and lead to clean combustion compared with conventional diesel engines. This prospective concept is not only used in vehicle engines but also used in large‐scale marine engines. In this study, the effects of injection strategies of dual fuels on combustion characteristics and emissions were investigated using the computational fluid dynamics (CFD) code CONVERGE coupled with a reduced n‐heptane/methane mechanism. The results showed that the effects of absolute injection timing (AIT) on the combustion characteristics and emissions are similar to those of traditional diesel engines. As the AIT varies from advanced by 4°CA to retarded by 4°CA, the peak values of the in‐cylinder pressure and temperature decrease gradually. However, a conventional trade‐off between NOx and soot/CO/HC/ISFC emissions can also be observed as the AIT is retarded. In contrast, relative injection timing (RIT) has more complicated impacts on the combustion and emissions characteristics. The in‐cylinder temperature distribution and concentration stratification change as the gas jet initially interacts with the pilot flame. The effects of the gas injection timing on the combustion characteristics and indicated specific fuel consumption are also similar to those of the AIT, but the emissions are quite different. The pilot injection timing shows minimal influence on the main combustion process. Better performance can be obtained with partially premixed combustion with a slightly late injection timing compared with that of the original (ORG) base case.

During the conceptual and preliminary design stage of a ship, designers need to ensure that the selected principal dimensions and parameters are good enough to deliver a stable ship (statically and dynamically) besides deadweight and speed. To support this, the initial intact stability of the proposed ship is required to be calculated, and in doing so, the lightship weight and its detailed breakdown are necessary to be known. After hull steel weight, machinery weight, mainly, marine propulsion and power generation machinery, play a vital role in the lightship weight estimate of a ship due to its robustness. The correct estimation of respective weights improves the accuracy of calculating a ship's initial stability typically to be designed and built. Hence, it would be advantageous for the designer to convince the ship owner. A total of 3006 marine propulsion (main marine diesel) engines and 348 power generation (auxiliary marine diesel) engines/generators of various power output (generators output for auxiliary engines), engine RPM and cylinder number of different engine makers are collected. These are analyzed and presented in both tabular and graphical forms to demonstrate the possible relationship between marine propulsion engine weight and power generation engine weight, and their respective power output, RPM, cylinder number, power-RPM ratio and power-RPM ratio per cylinder.In this article, the authors have attempted to investigate the behavior of marine propulsion engine weight and power generation engine/generator weight regarding engine power output, generator power output, engine RPM and cylinder number (independent variables). Further attempts have been made to identify those independent variables that influence the weight of the marine propulsion engine and power generation engine/generator (dependent variables), and their interrelationships. A mathematical model has thus been developed and proposed, as a guiding tool, for the designer to estimate the weight of main and auxiliary engines more accurately during the conceptual and preliminary design stage.

To prove the important role of battery electric buses (BEBs) in reducing carbon dioxide (CO2) emissions, we propose a framework to compare CO2 emissions between BEBs and conventional diesel buses (CDBs) based on low sampling frequency BEBs data at the city scale in Shenzhen. We applied the VT-Micro model to improve the estimation of CDBs’ CO2 emissions. A modal-activity-based method was implemented to reconstruct the second-by-second trajectories from the dataset as the input of the VT-Micro model. We updated the data of the Guangdong power generation mix to improve the estimation of BEBs’ CO2 emissions. The experiments showed that BEBs could reduce CO2 emissions by 18.0–23.9% in comparison with CDBs when the frequency of air-conditioning usage was low. In addition, BEBs tended to achieve more CO2 emission reduction benefits when the transit buses traveled at a low speed. Improving the traffic efficiency of road networks and promoting inter-provincial electricity trading are important to promote the adoption of BEBs.

This paper introduces the main composition, working principle and performance index of the suspension control system of medium-and low-speed maglev train. Relying on the suspension controller and suspension sensor of suspension control system of Beijing Metro S1, introduces the main technical requirements, design points and experimental acceptance requirements of suspension control system, and analyzes the difficulties and main problems during the use of Beijing Metro S1.

The paper presents purpose equations describing the uneven mixing depending on the number of the mixer blade impacts per unit of concrete weight as well as the weight of the mixture that have an impact on blades of the slow-speed mixer. Based on the literature review and analysis of the mixing process conducted in the Samara State Agricultural Academy, the design of the blade mixer was developed. The mixer consists of a body where there is a horizontal shaft with working bodies, made in the form of radial blades of helical shape. There are received equations that allow determining the concrete uniformity depending on a number of the impacts of the mixer blades per unit of the concrete weight as well as on the concrete weight that act on the blades of the slow-speed mixer. The power function is adequately described by the experimental results of 98 % confidence probability. In the studied areas of changes in independent factors rational values of the number of impacts per unit of the concrete weight is not less than 800 PCs/kg, as well as the concrete weight having impact on the blade of the slow-speed mixer is not more than 0,001 kg/PC.

According to the disadvantages of serious wear and heat fade of friction pad in frequent and high speed braking of friction brakes, and the insufficient power of electromagnetic brakes in low speed braking, a novel frictional-electromagnetic compound disk brake which combines both of these two brake principles is proposed for automotives in this paper. The excitation coils are designed based on the Zhang Yicheng theory model, and the compound brake prototype is manufactured based on the self-made magnetic brake pads and existing automotive brakes. The magnetic field and dynamic of the brake are simulated by using COMSOL Multiphysics software. The frictional–electromagnetic compound brake tests are implemented on the reconstructive disk brake simulation test bench. The experimental results show that the friction braking torque accounts for more than 90% of the compound braking torque in the process of compound braking, and the trend of the change is the same as that of the compound braking torque. When the initial braking speed exceeds 75 km/h, the electromagnetic braking torque does not increase with the increase in speed, instead, it decreases slightly because of demagnetization. The designed frictional–electromagnetic compound disk brake has good braking performance.

Too low an operating speed of trailer air braking systems may lead to an inhibition of the braking asynchrony of agricultural tractor trailer units. Improved braking dynamics advanced braking systems with an electronic control unit (e.g. Trailer EBS) provide a more rational solution for high speed agricultural vehicles. In this paper, an overview of other methods for developing the dynamic properties of air braking systems for agricultural trailers is described. This paper provides an examples of braking system design parameters optimization, using a variety of accelerating valves and dynamic properties correcting devises, also as well, by using simple systems with an electronic controllers. The described methods of dynamic properties improvements can be used to improve the speed and operation synchrony of the air braking systems of low-speed agricultural trailers. The paper presents the influence of some of the described methods, with different levels of complexity, on the properties of typical air braking systems.

Due to the low speed and heavy load conditions of slewing bearings, extracting of effective features for fault diagnosis and prediction is difficult but crucial. Moreover, challenges such as large data volumes, unlabeled and multi-source bring more difficulties for advanced prognosis and health management methods. To solve these problems, a novel method for performance degradation assessment of bearings based on raw signals is proposed. In this methodology, a combination of deep auto-encoder (DAE) algorithm and particle filter algorithm is utilized for feature extraction and remaining useful life (RUL) prediction. First, the raw vibration signal is employed to train parameters of a restricted Boltzmann machine to build the DAE model. Through encoding and decoding multi-source data, root mean square error of reconstruction error between the raw signal and reconstructed signal is employed to detect incipient faults of slewing bearings. Then, degradation trend model is established by particle filtering to predict RUL of bearings. The effectiveness of proposed method is validated using simulated and experimental vibration signals. Results illustrate that proposed method can evaluate the performance degradation process and RUL of slewing bearings.

The use of gas/LNG to supply marine engines in addition to tangible economic benefits is also a method of limiting emissions of harmful substances into the atmosphere and meeting strict environmental protection regulations, especially in special areas. The technology of supplying liquid and gas fuels (Dual Fuel) is most easily used in four-stroke engines but the highest thermal efficiency is ensured by combustion two-stroke piston engines. However, in the first two-stroke dual-fuel engines, the gas supply installation was more complicated than in the four-stroke engine. It resulted, among others from the necessity of compressing the gas to high pressures (15÷30 MPa), for which extremely energy-consuming multi-stage compression systems were needed. The complicated technical system is inherently prone to failures, which is why the dual-fuel low-speed two-stroke diesel engines remained for a long period in the design and experimental phase. In recent years, there has been a significant breakthrough thanks to the introduction of new solutions with the possibility of supplying two-stroke engines with low-pressure gas (less than 1.6 MPa). In recent years, many ships powered by two-stroke, dual-fuel internal combustion engines were commissioned. Some ship-owners owning a fleet of LNG carriers with two-stroke diesel engines that so far have been powered only by liquid fuels have decided to adapt them to gas combustion. This required the adaptation of the engine for gas combustion and the expansion of the supply gas fuel system. This paper is an attempt to analyse the legitimacy of introducing two-stroke, dual-fuel internal combustion engines into the propulsion system and adaptation of engines that are already used to burn gas in them. It presents the changes introduced on one of the LNG gas carriers consisting in adapting the engine to gas combustion through modification of the cylinder head and fuel supply installation. Parameter results of the modified engines obtained during sea trials have been presented. Both advantages and disadvantages resulting from gas combustion have been pointed out. Finally, the possibility of this solution application to other LNG carriers was assessed.

In low-speed two-stroke marine engines, the effect of connecting rod inertia is important for the tribo-dynamics of crosshead slipper-guide and piston skirt-liner. However, this has not been considered in previous research. Therefore, a new tribo-dynamic model that considers the connecting rod inertia is presented for the two lubricated translational joints, and the lubricant viscosity–temperature properties are accurately incorporated into the model. The modified extended backward differentiation formulate method is used to solve the nonlinear stiff differential equations effectively. The simulation results show that the effect of connecting rod inertia on the dynamic characteristics of two translational joints is mainly observed during the latter half of the upward stroke. For the crosshead slipper, the amplitude of the transverse velocity is increased by 30% at a crank angle of approximately 300° compared to the early model that ignored the connecting rod inertia. With the increase of the connecting rod mass, the secondary motions of both the crosshead slipper and the piston skirt are increased. Furthermore, a decrease of the connecting rod mass can reduce the friction losses of the engine.

The vast majority of unmanned aerial vehiches are propeller-driven with low speed. For higher speeds and longer ranges, new cost-effective microjets, which operate efficiently in both “fly-fast” and “loiter” modes are required. As a solution, a novel variable-cycle geared micro-turbofan architecture without the typical components of booster and low-pressure turbine is considered. This study discusses a key element, the low-pressure compression system. Instead of a separate and complicated booster to extract more power from the basic turbine, it is proposed to incorporate its positive functionality in the fan root. By preliminary and detailed fluid models, and structural concerns, systematic comparisons are made on demonstrative and representative cases to explore the feasibility of the proposal. Beyond the required very wide-chord design, the concept yields to a significantly increased pressurization and axial velocity at the fan root and exact opposite at the rest, causing extreme twist. The corresponding transonic stator root greatly increases downstream mixing losses. Moreover, a limitation is found to be the downstream compressor duct due to a notable increase in the diffusion requirements. Findings present that the concept is dramatically different from typical highly-loaded fans and this paper attempts to present new design guidelines.

Traffic simulation models often neglect the important role of motorcycles and assume a flow of various combinations of cars. This paper addresses how much different would be the behavior of a car driver while following a motorcyclist compared to cases in which a car follows another car, along with a segment of an urban highway in the non-congested flow. Recognition of such a difference might help to develop existing simulation models and to improve the behavior of car drivers in such a way to lead to lower accidents with motorcycles. To reach the goal, a GHR (Gazis-Herman-Rothery) model for car following is applied and data have been collected by video cameras during 15 min time intervals in three different days. Analysis of 198 car-motorcycle and 374 car-car following observations has indicated that when a car driver follows a motorcycle, keeps a higher headway (about 10 m in the low speed) with a lower acceleration/deceleration in comparison with the situation in which car driver follow another one. It means that the behavior of the follower car driver would be more cautious compared to situations in which a car driver follows another one, especially in space headways