Surface stress evolution and cracks prevention of ingots during the upsetting process

In this research, surface axial stress and propagation of surface transverse cracks on large ingots during hot forging process was studied using finite element modeling. The simulation results show that surface axial stress changes from compressive to tensile during the upsetting process. Large ingots which need to be upset and stretched several times are easy to form cracks at anvil overlapping part during stretching process. These surface transverse cracks are crack source and may rapidly propagate under surface axial tensile stress during the upsetting process. The effect of material, temperature, height-diameter ratio of billet, deformation speed, and friction coefficient between anvil and billet on the changing of surface axial stress was investigated. The results show that critical transformation point of surface axial stress from compressive to tensile has an obvious relationship with drum shape of the billet. In order to eliminate the surface axial tensile stress and prevent propagation of surface transverse cracks, a slim waist forging process was proposed based on the surface stress analysis. A quantitative designing method of slim waist billet was established for guiding industrial production

Numerical simulation and optimization of the casting process of a cast-steel wheel

The mechanism of formation and the regularity of shrinkage distributionin a cast-steel wheel were simulated by computer methods. SolidWorks softwarepackage was used to produce a three-dimensional model of the cast parts, and Experto ViewCastsoftware package was employed to simulate the casting process. The simulatedresults show that the mold filling was smooth and thus no splashing occurred. However, shrinkage and porosityappeared at the transition phase between the wheel-rim and web during the process of solidification. The reason for that isthe imperfect solidification sequence. The fast cooling rate in the final thin web position led to the block of feeding channel at the transition area. The foundry technique was improved successfully by computer-aided methods.The volume of shrinkage was reduced by applying an insulating material, which made thecastings solidify progressively as designed. The performance of the wheel produced by the improved technology agreed very well with the technical requirements

Comparative evaluation of the efficiency of the BG-Sentinel trap, CDC light trap and Mosquito-oviposition trap for the surveillance of vector mosquitoes

Distribution of the traps in the third week of each month. A. Liangtian (suburban area), B. Tonghe (urban area). Twelve each of BGS Traps, CDC Light Traps and MOTs were used to survey the mosquito density in Tonghe and Liangtian. (PDF 639 kb

A multimodal psychological, physiological and behavioural dataset for human emotions in driving tasks

Human emotions are integral to daily tasks, and driving is now a typical daily task. Creating a multi-modal human emotion dataset in driving tasks is an essential step in human emotion studies. we conducted three experiments to collect multimodal psychological, physiological and behavioural dataset for human emotions (PPB-Emo). In Experiment I, 27 participants were recruited, the in-depth interview method was employed to explore the driver’s viewpoints on driving scenarios that induce different emotions. For Experiment II, 409 participants were recruited, a questionnaire survey was conducted to obtain driving scenarios information that induces human drivers to produce specific emotions, and the results were used as the basis for selecting video-audio stimulus materials. In Experiment III, 40 participants were recruited, and the psychological data and physiological data, as well as their behavioural data were collected of all participants in 280 times driving tasks. The PPB-Emo dataset will largely support the analysis of human emotion in driving tasks. Moreover, The PPB-Emo dataset will also benefit human emotion research in other daily tasks

Distance Difference Algorithm Based on RSSI for Highway Vehicle Localization

Localization based on RSSI technology has been widely used because of low peripherals requirements, less cost and easy-to-use. With the rapid development of intelligent transportation, how to provide more efficient and safer driving environment has become the most important issue. The highway localization system is an important part of the entire intelligent traffic system. According to the characteristics of the high way environment localization, RSSI algorithm suits the best. However, the RSSI algorithm has some shortcomings inherently; therefore, in order to improve localization accuracy, this paper introduced the real-time environment factor and the distance- difference weighted centroid localization algorithm into the traditional weighted centroid algorithm. The simulation has proven that localization accuracy is enhanced by the distance-difference weighted centroid localization algorithm

Microstructure and Properties of Cladding Layers Prepared by Argon-Shielded Arc Cladding of CuZn40-WC Powders on Pure Aluminum Substrate

Aluminum and aluminum alloys have the advantage of a high strength-to-weight ratio, but their low hardness and poor wear resistance often cause wear damage. In the present study, the cladding layer was prepared using argon-shielded arc cladding of CuZn40-WC powders which were pre-coated on a pure aluminum substrate. The effects of WC proportion on the morphology, microstructure, and properties of cladding layers were investigated in detail. The results indicated that the optimal WC proportion in CuZn40-WC powders was 60 wt.%. With the increase of WC proportion, although the morphology of the cladding layer became slightly worse, the surface quality of the cladding layer was acceptable for industrial application until the WC proportion was 80 wt.%. Meanwhile, the top width and maximum depth of the cladding layer decreased. The maximum microhardness and optimal wear resistance of the cladding layer were 4.5 and 2.5 times that of the aluminum substrate, respectively. The increased microhardness and wear resistance were mainly attributed to the formation of Al4W in the cladding layer. The wear scar of the high wear resistance specimen was smoother and some bulk Al4W compounds were clearly observed on the wear surface

The Efficacy of Landscape-Level Conservation in Changbai Mountain Biosphere Reserve, China

<div><p>Anthropogenic landscape alteration is rather common in many protected areas (PAs), jeopardizing the efficacy of PAs conservation. However, the general consensus is that PAs still remain effective in habitat conservation. To assess the efficacy of landscape-level conservation, we examined landscape alterations in the Changbai Mountain Biosphere Reserve (CMBR), which was established in 1960 as a “flagship” protected area in China. Based on analyses of high-resolution satellite images and data of forest inventory, field survey and interview, we developed two new indexes to assess the efficacy of landscape conservation, i.e. the quality index of protected landscape and the interference index of anthropogenic landscape. From 1993 to 2012, the quality index increased from 74.48 to 75.50, and the interference index decreased from 0.49 to 0.06, suggesting that the overall quality of protected landscape improved and the degree of anthropogenic interference decreased in CMBR. The increase in landscape quality was mainly due to the progressive vegetation recovery of previous cutover land in the windthrow area, the cease of the use of the cultivated land, and the amelioration of spatial pattern of protected landscape. We conclude that the current landscape conservation methods used in CMBR are effective, and the method we developed has the potential to be used to assess the efficacy of landscape-level conservation in nature reserves worldwide.</p></div

Dechlorane plus (DP) in indoor and outdoor air of an urban city in South China: Implications for sources and human inhalation exposure

Dechlorane Plus (DP) is a chemical of emerging concern due to the restrictions on brominated flame retardant formulations. However, very little information is known about the occurrence of DP in indoor and outdoor air and its associated health risk to the exposed human population. In this study, we examined the concentrations and isomer profiles of DP in archived air samples collected from 14 homes, 6 offices, and 10 public microenvironments in Guangzhou, China in 2004-2005. The average (median) value of atmospheric sigma DP (sum of anti-DP and syn-DP) concentration in the three indoor air was 5.73 +/- 5.33 (3.62) for offices, 8.08 +/- 5.17 (6.87) for homes, and 57.27 +/- 83.08 (32.58) pg/m(3) for public microenvironments, respectively. sigma DP concentration was significantly higher in the public microenvironments than those in homes and offices. The arithmetic mean and median concentrations of sigma DP in outdoor air were 36.00 and 28.76pg/m(3), respectively. Spatially and temporally consistent indoor and outdoor samples comparison suggested that outdoor air might be a relevant source of DP for indoor air. Average anti-DP fractional abundance (f(anti) = 0.65 +/- 0.04) in all outdoor samples was similar to those reported in other studies and indistinguishable from that of the commercial mixture (f(anti) = 0.65). In contrast, a relatively large variation of f(anti) values was found in the indoor samples, suggesting a complex degradation process of DP existing in these microenvironments. The calculated average daily doses of sigma DP were in the range of 0.38-2.21ng/day for people intake through air inhalation, which was in the same order of magnitude compared with other exposure pathways for the general publics