Relative vibration identification of cutter and workpiece based on improved bidimensional empirical mode decomposition

Frontiers of Mechanical Engineering - In the process of cutting, the relative vibration between the cutter and the workpiece has an important effect on the surface topography. In this study, the...     

The biological mechanisms of butanol tolerance and the application of solvent-tolerant bacteria for environmental protection

Toxicity caused by the accumulation of butanol in fermentation media is an important factor limiting the concentration of butanol. There is currently no systematic research in place investigating the butanol tolerance mechanism of bacteria such as Clostridium acetobutylicum, which adapts to butanol stress and regulates its growth and metabolism. Here, research results related to the butanol tolerance of C. acetobutylicum are reviewed to understand the molecular basis of changes in butanol-tolerant strains. Organic solvent-tolerant bacteria play an important role in the fields of biofuel production, enzyme preparation and bioremediation. An analysis of limitations of the application of organic solvent-tolerant bacteria has revealed that future research should focus on combining the microbial tolerance phenotype with specific utilization to achieve an optimal balance between organic solvent tolerance and production. This review serves as a reference for the improvement and engineering of strains that tolerate organic solvents. © 2019 Society of Chemical Industry     

模块化汽车焊接夹具设计与开发

整车厂时常需要同时开发与制造多个车型的样车,因此汽车焊装夹具需要具有高通用性,以保障开发及制造周期满足项目要求,并且能够减少成本。因此,开发出高通用模块化焊接夹具,以实现快速设计、快速制造的目的。     

PVC⁃U排水管道中重金属铅的浸出研究

研究了3种添加铅稳定剂的铅总量和硬聚氯乙烯（PVC?U）管道产品在不同时间，温度及pH下的浸出规律，并讨论了浸出机理。结果表明，3种产品浸出规律一致：铅浸出量随时间增加先增加后减少，浸出4 h时浸出量最大；温度对铅浸出量影响显著，铅浸出量随温度的增加持续增加；铅在强酸性环境的浸出量大于在强碱性环境下的浸出量，在偏碱性环境下的浸出量最少。     

Nonlinear robust dual-loop control for electro-hydraulic load simulator

This paper investigates on the high performance torque control of electro-hydraulic load simulator (EHLS). In order to suppress actuator׳s motion disturbance, a nonlinear robust dual-loop control scheme is developed, which consists of a open-loop nonlinear velocity feed-forward compensator and a closed-loop nonlinear deterministic robust torque controller. The main function of the open-loop compensator is to decouple actuator׳s active motion disturbance, whereas the torque loop controller aims at guaranteeing the dynamics performance of tracking torque reference. Besides actuator׳s motion disturbance, both the nonlinearity characteristics and friction problem of the EHLS system are taken into consideration in this paper. The effectiveness of the developed method are verified through comparative co-simulations and experiments.     

高大模板支撑系统在施工中的应用

搭设高度8m及以上;搭设跨度18m及以上;施工总荷载15k N/m2及以上;集中线荷载20KN/m及以上等属于高大模板(规范术语),亦称为高支模(工地叫法)。结合湛江市鉴江供水闸坝工程,介绍高支模的设计要点、施工工法、质量控制措施,并对其使用效果进行整理和分析。     

Identification of AMR decompressed audio

More and more conversation recordings from phone calls are used as forensic evidence. To decide whether an unknown speech recording comes from mobile phone or not becomes an important issue in digital audio forensics. The communicating conversation recorded by mobile phones is encoded by Adaptive Multi-Rate (AMR) audio codec, which was adopted as the standard speech codec by 3GPP and widely used in GSM and UMTS. Therefore, AMR decompressed audio detection can be used to identify the source of the digital audio recording. Furthermore, it is helpful to locate the forgery position of the splicing AMR decompressed audio for forensic purposes. In this article, we focus on the identification of AMR decompressed audio, namely, given the waveform of an audio, we wish to identify whether it has been previously compressed by AMR codec or not. The artifacts introduced by the AMR codec will help to detect the source of the recordings. Based on our analysis, we find that the sample repetition rate of the AMR decompressed waveform is significantly greater than the regular waveform. Therefore, we employ the sample repetition rate as a feature to identify the AMR decompressed audio. The experimental results show that this feature is robust and effective.     

Sexual self-presentation on social network sites: Who does it and how is it perceived?

The aims of this study were to investigate (a) the role of peer factors in adolescents’ sexual self-presentation on social network sites, and (b) how adolescents who present themselves sexually online are evaluated by others. 238 high school students (aged 12–18) evaluated either a sexual or non-sexual online presentation of same-sex and opposite-sex peers. Moreover, they filled in a questionnaire about their own self-presentation behavior. Findings showed that peer norms played a crucial role in whether adolescents posted sexual pictures of themselves online. Moreover, need for popularity was a strong predictor for posting such pictures. Girls who presented themselves in sexual ways were evaluated more negatively by other girls but more positively by boys. Similarly, boys who presented themselves in sexual ways were evaluated more positively by girls but not by boys.