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Diesel particulate filter (DPF) is considered as an effective method to control particulate matter (PM) emissions from diesel engines, which is included in the mandatory installation list by more and more national/regional laws and regulations, such as CHINA VI, Euro VI, and EPA Tier3. Due to the limited capacity of DPF to contain PM, the manufacturer introduced a method of treating deposited PM by oxidation, which is called regeneration. This paper comprehensively summarizes the most advanced regeneration technology, including filter structure, new catalyst formula, accurate soot prediction, safe and reliable regeneration strategy, uncontrolled regeneration and its control methods. In addition, due to the change of working conditions in the regeneration process, the additional emissions during regeneration are discussed in this paper. The DPF is not only the aftertreatment device but also can be combined with diesel oxidation catalyst (DOC), selective catalytic reduction (SCR) and exhaust recirculation (EGR). In addition, the impact of DPF modification on the original system of some old models has been reasonably discussed in order to achieve emission targets.

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Screw is an important part in the mechanical field, and plays a significant role in variety of applications. Because of its complex and changeable shape, the design and processing of the screw are difficult. In order to improve the design and production efficiency of the screw, the CADDCAM system of the screw is studied. Based on UGNX8.0 software, visualstudio2010 is used as a programming tool, and the secondary development tools of NX Open, Block UI Styler and Men-u Script are used to achieve the development of screw CADDCAM system. The objective of this article is to describe the research on integrated CAD system for designing trajectory of screw manufacturing. The main functions of the system include quickly creating a three-dimensional model of the screw, reading the parameters of the three-dimensional model of the screw, and solving the tool trajectory when the screw is processed by internal whirlwind milling. Finally, through relevant examples, the function of the developed screw CADDCAM system is verified.