Design of Integrated Chassis Control logics for AFS and ESP

The performance of most electronic chassis control systems in the past has been optimized individually. Recently, a great research effort has been dedicated to the integration of chassis control systems in an effort to improve the vehicle performance. This involves orchestration of individual control modules so that they can jointly contribute to the enhancement of their control effect. In this research, two integrated control logics for AFS (Active Front Steering) and ESP (Electronic Stability Program) have been developed. Of the two logics, one uses a supervisor that rules over the individual modules. The other logic uses a CL (Characteristic Locus) method, which is a frequency-domain multivariable control technique. The two logics have been tested under various driving conditions to investigate their control effects. The results indicate that the proposed integrated control logics can yield vehicle performance that is superior to that of the individual control modules without any integration scheme.     

Reaction characteristics of the diesel oxidation catalyst of particulate matters from the diffusion flame of a oiler burner

The objective of this experimental study is to investigate the characteristics of the size distribution and the number concentration of PM (particulate matters) emitted from the diffusion flame of a boiler burner, which has the same type of combustion as a diesel engine. This study is performed to investigate the emission characteristics of nanoparticles generated from diffusion combustion in diesel fuel, and it considered fuel factors and the reaction characteristics of the nanoparticles on the DOC (Diesel oxidation catalyst). The factors examined in this experiment included the sulfur content in the fuel, the blend of the diesel fuel containing biodiesel and bio-ethanol, and the concentration of engine oil (0.1% and 1.0%) blended with diesel fuel. The particle size distribution of the nanoparticles exhausted from the boiler burner was measured by an SMPS (scanning mobility particle sizer). The number concentration of PM that were smaller than 70 nm in diameter greatly increased in the rear of the DOC when fuel containing 250 ppm of sulfur was used. The experiment also suggested that the particle number concentration in both the front and rear of the DOC was lower when ULSD (ultra low sulfur diesel) fuel blended with biodiesel and bio-ethanol, which are oxygenated fuels, was used than when only ULSD fuel was used. The higher the content of engine oil in the fuel, the higher the particle number concentration was in the front and rear of the catalyst. When the first dilution air temperature is increased from 30°C to 180°C, the nanoparticle number concentration dramatically dropped in the rear of the catalyst when fuel containing 250 ppm of sulfur was used, while the particle size distribution remained almost the same when the fuel with engine oil was used.     

Theoretical studies of active power/angle sub-matrix in power flow Jacobian for power system analysis

Properties of the active power/angle sub-matrix in the power flow Jacobian for power system analysis are studied. The sub-matrix is a dominant and irreducible matrix under very general conditions of power systems, so that it is invertible. Also the necessary conditions for its singularity are given. These theoretical results can be used to clarify the ambiguous understanding of the sub-matrix in current literature, and also provide the theoretical foundations for the applications based on reduced power flow Jacobian. Numerical simulation on the IEEE 118-bus power system is used to illustrate our results.     

Isotopic composition of carbon and nitrogen of suprabenthic fauna in the NW Balearic Islands (western Mediterranean)

Stable isotope (δ¹³C and δ¹⁵N) analyses were performed on suprabenthic fauna collected in the western Mediterranean (NW Balearic Islands), at depths ranging between 350 and 780 m. Samples were collected seasonally at bi-monthly intervals during six cruises performed between August 2003 and June 2004, using a Macer-GIROQ suprabenthic sledge (0.5 mm mesh size). Twenty-four separate species (5 mysids, 12 amphipods, 2 cumaceans, 2 isopods, 1 euphausiid, 1 decapod and 1 fish) and bulk copepods were analyzed on a seasonal basis for stable carbon and nitrogen isotopes. Stable nitrogen isotope ratios (δ¹⁵N) ranged from 2.3‰ (the amphipod Lepechinella manco in September 2003) to 13.0‰ (the amphipod Rhachotropis caeca in August 2003). δ¹³C values ranged from − 24.2 (the cumacean Campylaspis sulcata in June 2004) to − 16.1 (the amphipod Bruzelia typica in November 2006). Both δ¹³C and δ¹⁵N values suggest that there are three trophic levels within the suprabenthic community. However, considering the bathymetric range of the species, the results suggest that the deepest assemblage supported only two trophic levels. The stable isotope ratios of suprabenthic fauna displayed a continuum of values and confirmed a wide spectrum of feeding types (from filter-feeders to predators). In general, and in spite of the poor knowledge about diets available for most suprabenthic species, higher δ¹⁵N were found for carnivorous amphipods (e.g. Rhachotropis spp., Nicippe tumida) consuming copepods. Low overlap for δ¹³C and δ¹⁵N values was observed, though δ¹⁵N values where less variable than δ¹³C, which suggests high resource partitioning in this assemblage. Seasonal variations in isotopic composition for both δ¹³C and δ¹⁵N were low (less than 1‰ and 3‰, respectively) and variable depending on species. Low correlations between δ¹³C and δ¹⁵N of suprabenthic fauna were found for all periods studied, though increasing from February 2004 to June 2004 (after the main peak of primary production in surface). C:N ratio (indicator of lipid content) showed higher values in summer than in winter. This suggests that lipid content may explain the seasonal patterns of δ¹³C variability and, due to the increase of storage products in phytoplankton and zooplankton, it possibly indicates the peak of primary production at the surface.     

预应力CFRP板加固钢板轴心受拉行为分析

首先分析比较预应力的施加方法和锚固方式,然后基于一维线弹性理论,对预应力碳纤维增强复合材料(CFRP)板加固钢板体系的受力过程进行分阶段分析,得到在张拉预应力和受载工况下CFRP板、钢板、胶层的应力分布解析式及CFRP有效粘结长度公式、弹性压缩带来的预应力损失值;最后利用ANSYS中Solid95三维单元进行有限元模拟对比分析。结果表明:直接张拉CFRP板能有效控制预应力及其加固效果,比间接法施加预应力有更多优势;采用高强螺栓连接的平板夹具锚传递大部分荷载,改善了非预应力粘贴加固界面的薄弱特点;该理论分析及有限元模型是可靠、有效的。     

Assessment of the pedestrian friendliness of a vechicle using subsystem impact tests

Annually, thousands of unprotected pedestrians are killed or suffer serious injuries in accidents with moving vehicles. Numerous automobile organizations have performed research on pedestrian safety. The European Enhanced Vehicle- Safety Committee (EEVC), Working Group 17 (WG17) proposed three component subsystem tests to evaluate the friendliness of a vehicle to pedestrians: the legform to hood test, the upper legform to bonnet leading edge test and the headform to bonnet top test. In assessing the pedestrian friendliness of a vehicle, the present study adopted the WG17 regulations of the three component subsystem tests. We herein describe in detail a finite element subsystem model built to analyze the pedestrian friendliness of a vehicle using LS-DYNA. The first objective of this study was to simulate these three component subsystem impact tests and evaluate car front aggressiveness. The second objective was to analyze the frontal structures of a vehicle and, based on the simulation results, identify dangerous areas and provide suggestions for vehicle front design that may decrease pedestrian injuries. The analysis of these models and the results obtained may be used to help evaluate the pedestrian friendliness of a vehicle and guide the future development of pedestrian-friendly vehicle technologies.     

Hydroplaning simulations for tires using FEM,FVM and an asymptotic method

Hydroplaning tires have been frequently simulated using commercial explicit FEM (Finite Element Method) codes. However, these simulations are slow, and the result of the lift force is so oscillatory that the hydroplaning speed cannot be accurately determined. Thus, in the author’s previous study, a new methodology using FDM (Finite Difference Method) code and an FE tire model iteratively was proposed. However, this full iteration method still required a long computation time, especially for patterned tires. Thus, in this study, the full iteration methodology was modified such that no iteration or only one additional iteration was needed at each speed. Then, by applying the full iteration method, no iteration method and one iteration method, the hydroplaning speeds of a straight-grooved tire were determined, and it was noted that the hydroplaning speed obtained from the one iteration method was almost the same as that obtained from the full iteration method. Moreover, the hydroplaning speeds of two patterned tires were determined using the one iteration method, and they were compared with the hydroplaning speeds obtained experimentally.     

Estimation of the adhesion force for a disc brake in a skid control condition

The performance of brakes has become important due to increased train speeds. The brake system of a train must possess a large brake force to stop the train safely within a limited stopping distance. However, an excessive brake force deteriorates the ride comfort and causes the train to skid. Therefore, it is necessary to control the brake force within the adhesion force limit. This paper presents an analytical method to estimate the relationship between the brake and adhesion forces of a disc brake system. This method has been applied to the actual disc braking control system of the Korea High-Speed Train (HSR350x), and the adhesion force is estimated in an actual skid condition.     

Comparison of Microbubble and Air Layer Injection with Porous Media for Drag Reduction on a Self-propelled Barge Ship Model

Ship resistance issues are related to fuel economy, speed, and cost efficiency. Air lubrication is a promising technique for lowering hull frictional resistance as it is supposed to modify the energy in the turbulent boundary layer and thereby reduce hull friction. In this paper, the objective is to identify the optimum type of air lubrication using microbubble drag reduction (MBDR) and air layer drag reduction (ALDR) techniques to reduce the resistance of a 56-m Indonesian self-propelled barge (SPB). A model with the following dimensions was constructed: length L?=?2000 mm, breadth B?=?521.60 mm, and draft T?=?52.50 mm. The ship model was towed using standard towing tank experimental parameters. The speed was varied over the Froude number range 0.11–0.31. The air layer flow rate was varied at 80, 85, and 90 standard liters per minute (SLPM) and the microbubble injection coefficient over the range 0.20–0.60. The results show that the ship model using the air layer had the highest drag reduction up to a maximum of 90%. Based on the characteristics of the SPB, which operates at low speed, the optimum air lubrication type to reduce resistance in this instance is ALDR.     

Law and Characteristics Analysis of Domestic Tunnel Construction Accidents from 2006 to 2016北大核心CSCD

With the rapid development of tunnel construction in China, strengthening statistical studies of domestic tunnel construction accidents is of great significance in order to understand the safety status of tunnel construction and the development trends of tunnel construction accidents and for exploring the direction of future scientific re-search. There were 89 tunnel construction accidents in China (not including subway tunnels or municipal tunnels)from 2006 to 2016. The characteristics of these accidents are analyzed in terms of time distribution, spatial distribu-tion, grade and type of accident according to the statistics by means of line charts, bar charts and pie charts. Corre-sponding prevention and control recommendations are put forward considering the factors such as year, month, work-ing day, time period, region, location, grade and type. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.