Transient Dynamic Characteristics of a Non-Pneumatic Mechanical Elastic Wheel Rolling Over a Ditch

The transient dynamic characteristic of a tire, which has a significant effect on vehicle handling stability and ride comfort, is difficult to study in detail because of its highly non-linear behavior. In this study, the transient dynamic characteristics of a non-pneumatic wheel, called the mechanical elastic wheel (MEW), which was rolling over a ditch were investigated by the explicit dynamic finite element (FE) method. A three-dimensional FE model of MEW considering geometric nonlinearity, material nonlinearity and large contact deformation between the wheel and the road, was established. For the validation of the accuracy and reliability of the FE model of MEW, the simulation and the experimental results of the radial stiffness and footprint of MEW were compared and analyzed. A dynamic simulation of the validated FE model of MEW rolling over a ditch was conducted using the ABAQUS/Explicit program. The equivalent stress and the contact stress generated during the process of the rolling MEW impacting the ditch were studied in detail. The effect of the rolling speed on the transient dynamic characteristics was also analyzed based on the simulation results. The simulation results could provide guidance for the optimization of the MEW structure and vehicle dynamics.     

Experimental Investigation of Impacts of Injection Timing and Pressure on Combustion and Particulate Matter Emission in a Spray-Guided GDI Engine

A detailed investigation of the impact of injection timing and injection pressure on combustion and particles of a spray-guided GDI engine was conducted, under different engine operating conditions. The results indicated that, more proportion of large particles were emitted when increasing engine load, and the peak of accumulation mode particles moved toward smaller size when rising engine speed. With retarding the injection timing, the in-cylinder pressure and heat release rate rose first and then dropped at 2000 rpm, but they continuously rose at lower or higher speed conditions. The total particles concentration curves at all cases showed a trend of U-shape, and the corresponding timing of the lowest particles concentration advanced as the engine speed or load increased. The minimum value of emitted particles first rose and then fell when increasing load at 2000 rpm conditions, and it continuously rose when increasing speed at 40 Nm conditions. Generally, injection pressure did no sensitively affect combustion process except that it showed a relatively strong impact at low load conditions. However, particulate matter could be effectively inhibited by elevating fuel pressure from 5.5 to 11.5 MPa at all cases. In detail, the total particles concentration continuously fell at low speed and mid speed-high load cases, but it showed a rose trend when further increase fuel injection pressure at mid speed-low load and high-speed conditions.     

Modeling of Double Lane Change Maneuver of Vehicles

Lane change maneuver is one of most riskiest driving tasks. In order to increase the safety level of the vehicles during this maneuver, design of lane change assist systems which are based on dynamics behavior of driver-vehicle unit is necessary. Therefore, modeling of the maneuver is the first step to design the driver assistance system. In this paper, a novel method for modeling of lateral motion of vehicles in the standard double-lane-change (DLC) maneuver is proposed. A neuro-fuzzy model is suggested consisting of both the vehicle orientation and its lateral position. The inputs of the model are the current orientation, lateral position and steering wheel angle, while the predicted lateral position and orientation of the vehicle are the outputs. The efficiency of the proposed method is verified using both simulation results and experimental tests. The simulation and experimental maneuvers are performed in different velocities. It is shown that the proposed method can effectively reduce the undesirable effects of environmental disturbances and is significantly more accurate in comparisons with the results in the recent available papers. This method can be used to personalize the advanced driver assistance systems.     

Evaluation and Measurement the Recovered Energy from Automobile Suspension in the Operation Conditions

The purpose of this paper is to verify if it is possible to recover the energy from automobile suspensions, using a system who replace the shock absorber. The system consists of an electric generator, a mechanical system for transforming the translation of body car in rotational movement and an electronic control system. The tests were made on three road types, according to ISO 8608/1995 with four different driving speeds. The results showed that a significant quantity of energy was recovered during the test on inferior type of road, even at reduced speed. For the superior type of the road, the energy can be recovered only at high speed. The parameters that influences the system capacity of recovering energy are gross weight of the vehicle, road type and the vehicle speed.     

Acoustical Characteristics of the Air Filter in the Engine Intake Air Cleaner

Linear acoustic theory is used for estimating the acoustical performance of the air cleaner box composed of the porous filter and encasing box in the engine intake system. The pleated filter structure is modeled as coupled multiple ducts having permeable micro-perforated walls and rectangular section, in which each duct area is assumed being homogeneous or inhomogeneous. Mathematical models describe the sound propagation within the narrow duct considering the visco-thermal effect at the filter pleats. For the validation, transmission loss (TL) is measured, and a change in TL spectrum is clearly observed by including the filter into the box. It is shown that the predicted TL counting the effect of visco-thermal loss agrees reasonably well with the experimental results. Noticeable effects of the filter on the TL are observed as highly smoothing effect at high frequencies and enhancing the TL magnitudes at troughs and lobes at low frequencies. Comparing homogeneous and inhomogeneous channel modelings, the latter is superior in precisely predicting the trough frequencies of TL curve, but the former is a bit better in predicting its magnitude. Parametric study on material and shape factors reveals that the number of pleats, length of the pleated filter, and distance between neighboring pleats are the key factors in determining the TL. It is concluded that an air filter element that has small number of long pleats with high flow resistance would bear the best acoustical performance among all designs.     

Allocation control algorithms design and comparison based on distributed drive electric vehicles

For a distributed drive electric vehicle (DDEV) which is equipped with redundant actuators, allocation control is a key technique. Three different allocation control algorithms are designated with fixed efficiency matrix, dynamic efficiency matrix, and direct yaw moment distribution, respectively. All these algorithms are applied in a vehicle stability control system with hierarchical control structure and evaluated from three aspects, namely, control precision, real-time characteristics, and control energy. Comparison results demonstrate that the algorithm with dynamic efficiency matrix has the best comprehensive performance, which is also validated in field tests based on a DDEV equipped with four motors.     

Deterring the dauntless—appraising the effects of naval deterrence against the Somali piracy

This article considers whether the Somali pirates were deterred by the naval task forces between the years 2009 and 2013. By disaggregating data and using previously unpublished records regarding the naval operations, two areas of operations are identified as potential periods of deterrence. The article uses a model of asymmetric deterrence to study the outcomes and equilibria of the navy-pirate interaction. It is found that the naval operations eventually did deter the Somali pirates in the Gulf of Aden, but that this objective was not met in the Somali Basin. It is concluded that the operational focus on the Gulf of Aden coupled with the fact that the area is relatively smaller than the Somali Basin enabled the naval credibility, thus effectively denying the pirates access to the sea. Conversely, limited attention by the naval units and the long Somali southern coast with its open waters impeded naval control in the Somali Basin. In connection to these findings some conclusions regarding naval deterrence are discussed.     

Enhancing the Efficiencies of Organic Photovoltaic and Organic Light-Emitting Diode Devices by Regular Nano-Wrinkle Patterns

Organic photovoltaic (OPV) cells and organic light-emitting diodes (OLEDs) are energy harvesting and generation devices that have attracted great attention these years because of their low costs, thin film structures, flexibility and environment-friendly manufacturing processes. For such thin film devices, photon management methods that increase the light absorption of OPV cells and the light extraction from OLEDs are highly desirable. Here, we report the experimental efforts to fabricate geometrically tunable and spontaneously formed nano-wrinkle structures with large areas, and the theoretical results on photon management with the nano-wrinkles.     

Detecting Premature Ventricular Contraction in Children with Deep Learning

Premature ventricular contractions (PVCs) are abnormal heart beats that indicate potential heart diseases. Diagnosis of PVCs is made by physicians examining long recordings of electrocardiogram (ECG), which is onerous and time-consuming. In this study, deep learning was applied to develop models that can detect PVCs in children automatically. This computer-aided diagnosis model achieved high accuracy while sustained stable performance. It could save time and repeated efforts for physicians, enabling them to focus on more complicated tasks.This study is a first step toward children’s PVC auto-detection in clinics. Further study will improve the model’s performance with optimized structure and more data in different sources, while facing the challenges of the variety and uncertainty of children’s ECG with heart diseases.     

Multi-Component Model of Diesel Sprays Under High Injection Pressure

The combustion efficiency of a diesel engine depends not only on spray characteristics but also on fuel-air mixing characteristics. Based on the original spray model, a new spray model is established in this paper to accurately predict the diesel spray, and then a multi-component evaporation model is added into it. The model takes the influence of component concentration gradient and species on its evaporation rate in the liquid phase into account. This paper studies the spray characteristics (spray penetration, spray angle and spray morphology) and fuel-air mixing characteristics (spray area, spray volume and air entrainment mass) using the spray model, and the results are compared with the experimental results. The comparison shows that the simulated spray penetration and spray angle are close to the experimental results with the average deviations less than 3%. Moreover, this paper studies the spray area, spray volume and air entrainment using empirical formula under different conditions. And the maximum deviations of the spray volume, spray area and air entrainment mass are less than 5% as compared with the test values. Overall, this spray model can predict the diesel spray characteristics and fuel-air mixing characteristics under high injection pressure accurately.