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In the field of low-frequency noise control, the acoustic metamaterials have received extensive attention from researchers. However, the existing work mainly focuses on small structures with fixed boundaries, which is quite different from engineering applications. Based on the membrane-type acoustic metamaterials, this paper uses a rigid thin plate to replace the tensioned membrane, design and manufacture of two new types of local resonance structure and studies their sound insulation properties. First, the metamaterial samples with a small size of 100mm in diameter and a large-size square with a side length of 506mm were produced, and the sound TL of the two was tested through the impedance tube and the reverberation chamber-anechoic chamber, respectively. The results show that the new structure can form an obvious sound insulation frequency band at low frequencies. Based on the finite element method, a metamaterial acoustic transmission loss calculation model is established.

Knock in gasoline engines at higher loads is a significant constraint on torque and efficiency. The anti-knock property of a fuel is closely related to its research octane number (RON). Ethanol has superior RON compared to gasoline and thus has been commonly used to blend with gasoline in commercial gasolines. However, as the RON of a fuel is constant, it has not been used as needed in a vehicle. To wisely use the RON, an On-Board Separation (OBS) unit that separates commercial gasoline with ethanol content into high-octane fuel with high ethanol fraction and a lower octane remainder has been developed. Then an onboard Octane-on-demand (OOD) concept uses both fuels in varying proportion to provide to the engine a fuel blend with just enough RON to meet the ever changing octane requirement that depends on driving pattern.

With the improvement of vehicle comfort requirements of market users, NVH performance has been paid more and more attention. Especially the pure electric passenger vehicle is lack of combustion engine noise masking effect, it is more likely to cause the drivers attention for any abnormal noise. In the steering operation under the low speed acceleration of pure electric vehicles, the cabin interior noise derived from the road and the wind is relatively low, and there is not marketing effect of traditional internal combustion engine noise, any slight abnormal noise is more likely for the drivers and passengers feel unsafe and complain. However, there is lack of systematic analysis and research on the untypical NVH problem in the automotive industry. This paper systematically expounds the test and analysis process of abnormal noise.

With the continuous improvement of positioning technology and industry demand, the shortcomings of each sensor are constantly amplified. Only relying on a single sensor, the demand of high-precision positioning and mapping for intelligent vehicles is difficult to be satisfied. The accuracy of system positioning and mapping is reduced due to the loss of feature points in pure visual SLAM as the environmental characteristics are not obvious or the texture is not abundant. IMU is a sensor with low cost and high update frequency, which can correct the running trajectory in real time and reduce the error of environmental factors on visual sensor data. Therefore, a method based on ORB_SLAM2 algorithm and VINS-Fusion algorithm, the stereo camera information and inertial measurement unit information are extracted and fused in robot operating system is proposed.

The spark ignition engine particulate number (PN) emissions have been correlated to a particulate matter index (PMI) in the literature. The PMI value addresses the fuel effect on PN emission through the individual fuel species reactivity and vapor pressure. The latter quantity is used to account for the propensity of the non-volatile fuel components to survive to the later part of the combustion event as wall liquid films, which serve as sources for particulate emission. The PMI, however, does not encompass the suppression of vaporization by the evaporative cooling of fuel components, such as ethanol, that have high latent heat of vaporization. This paper assesses this evaporative cooling effect on PN emissions by measurements in a GDI engine operating with a base gasoline which does not contain oxygenate, with a blend of the gasoline and ethanol, and with a blend of the gasoline, ethanol, and a hydrocarbon additive so that the blend has the same PMI as the original gasoline.

In this work, the effects of engine operational parameters, λ, spark timing, and compression ratio, on knock tendency and intensity as well as H2 supplementation are studied. We postulated, verified and eventually used the duration from ignition to 70% mass fraction burnt (MFB0-70%) as an explanatory variable to describe the knock tendency and intensity. In this manner, the physical factors and fuel factors that are introduced by the differences in test conditions can be differentiated. Practically, in terms of percentage of knocking cycles or the spark timing at audible knock, knock tendency decreases as λ increases and increases with H2 supplementation. However, when MFB duration is taken into account, then for the same MFB duration, knock tendency increases as λ increases and decreases with H2 supplementation.

We studied the influence of extreme pressure (EP) antiwear additive on the emission and distribution of particulate matters (PMs), since EP antiwear additive is necessary to improve the property of lubricating oil with the downsizing development of engines. We used a four-cylinder, turbocharged, and inter-cooled system with SAE15W-40 lubricant diesel engine. Pure diesel and fuel blends with varying weight percentages (0.5%, 1.0%, and 1.5%) of EP antiwear additive were used. Engine speed increased by increments of 400 from 1,200 rpm to 2,800 rpm under medium load and full load. The DMS500 was used to acquire particle data, and the Wave Book was employed to record oil and cylinder pressure. Conclusions drawn from the experiments suggest that EP antiwear additive has significant effects on PM emissions and distributions. Increments and decrements were observed on the number of accumulation mode particles and nucleation mode particles with BDAW-0.5.

The Structure and principle of the hydraulic free piston engine (HFPE) is analyzed, and the mathematical model is established according to the feature of the working principle. The transient processes are analyzed through simulation. The result shows that: 1) the working cycle of the HFPE is unsymmetrical, the compression stroke time is 16ms and the expansion stroke time is 10ms. 2) The speed of the power piston is faster than the conventional diesel engine, the maximum speed in the compression stroke is 12m/s and the maximum speed in the expansion stroke is 17m/s. 3) The acceleration is bigger than the conventional engine, the maximum value is 16500m/s2, at the top dead centre and the smallest value is 3500m/s2 at the bottom dead centre.