Study on the ignition process of a segmented plasma torch

Direct current plasma torches have been applied to generate unique sources of thermal energy in many industrial applications. Nevertheless, the successful ignition of a plasma torch is the key process to generate the unique source （plasma jet）. However, there has been tittle study on the underlying mechanism of this key process. A thorough understanding of the ignition process of a plasma torch will be helpful for optimizing the design of the plasma torch structure and selection of the ignition parameters to prolong the service life of the ignition module. Thus, in this paper, the ignition process of a segmented plasma torch （SPT） is theoretically and experimentally modeled and analyzed. Corresponding electrical models of different stages of the ignition process axe set up and used to derive the electrical parameters, e.g. the variations of the arc voltage and arc current between the cathode and anode. In addition, the experiments with different ignition parameters on a home-made SPT have been conducted. At the same time, the variations of the arc voltage and arc current have been measured, and used to verify the ones derived in theory and to determine the optimal ignition parameters for a particular SPT.

Study on flaw identification of ultrasonic signal for large shafts based on optimal support vector machine

Automatic identification of flaws is very important for ultrasonic nondestructive testing and evaluation of large shaft.A novel automatic defect identification system is presented.Wavelet packet analysis(WPA)was applied to feature extraction of ultrasonic signal,and optimal Support vector machine(SVM)was used to perform the identification task.Meanwhile,comparative study on convergent velocity and classified effect was done among SVM and several improved BP network models.To validate the method,some experiments were performed and the results show that the proposed system has very high identification performance for large shafts and the optimal SVM processes better classification performance and spreading potential than BP manual neural network under small study sample condition.

Influence of cutting off position of plasma filament formed by two-color femtosecond laser on terahertz generation

Femtosecond laser filamentation is a method of generating terahertz, which has wide application in terahertz subwavelength resolution imaging. In this paper, the plasma filament formed by femtosecond laser focusing was terminated with an alumina ceramics at different positions and the influence of the cutting off position of the plasma filament on the terahertz wave was studied. The results showed that the terahertz amplitude increases as the position approaches the end of the filament gradually. The stability of amplitude and peak frequency of the terahertz generated by the filament formed by two-color femtosecond laser via a lens with a longer focal length is lower than that through a lens with a shorter focal length, especially the terahertz amplitude at the end of the filament. The study will be helpful for future researchers in the field of THz sub-wavelength imaging utilizing femtosecond laser filament.

MODELING METHOD OF 4D INFORMATION MODEL FOR COOPERATIVE DESIGN OF MECHANICAL PRODUCTS

The continuous developing features in the design of mechanical product and based on 3D entity model is aimed at, and the extension of the 4-dimensional model with the process of designing, the knowledge described model on the level of semantic understanding and summarizing the designing process and the way of discovering knowledge from multi-information model are studied. On the basis of designing the broad sensed collaborative system, through discussion of the relationship between the implicit knowledge of the users and the designing knowledge as well as commanding all the designing links, taking advantage of the way of concluding and deducting in the concept of the designers, the synthetic knowledge unit formed in the dynamic process from the conception design t9 the last design is schemed out, and the knowledge discovered principle in the dynamic designing process of the mechanical products and the key technology in its implementation under the milieu of network is brought forward.

An Open IoT Framework Based on Microservices Architecture

With the continuous development and evolvement of Internet of Things(Io T), monolithic application becomes much larger in scale and even more complex in structure. This leads to poor scalability, extensibility and maintainability. In response to those challenges, microservice architecture has been introduced in the field of Io T application, due to its flexibility, lightweight and loose coupling. However, the existing Io T framework of microservice mainly focus on a specific domain, therefore, this greatly limits its application. In this paper, we propose a general microservice system framework for the Io T application, which is a better scalable, extendable and maintainable architecture. We introduce its system design and related microservices, and emphasize on core service and device communication from service layer to physical layer. It has better capacity to support interoperability and accommodate heterogeneous objects. In addition, this framework can easily achieve more application integration such as automation, intelligence, Geo service and Big Data.

Mining Compatibility Rules from Irregular Chinese Traditional Medicine Database by Apriori Agorithm

This paper aims to mine the knowledge and rules on compatibility of drugs from the prescriptions for curing arrhythmia in the Chinese traditional medicine database by Apriori algorithm. For data preparation, 1 113 prescriptions for arrhythmia, including 535 herbs （ totally 10884 counts of herbs） were collected into the database. The prescription data were preprocessed through redundancy reduction, normalized storage, and knowledge induction according to the pretreatment demands of data mining. Then the Apriori algorithm was used to analyze the data and form the related technical rules and treatment procedures. The experimental result of compatibility of drugs for curing arrhythmia from the Chinese traditional medicine database shows that the prescription compatibility obtained by Apriori algorithm generally accords with the basic law of traditional Chinese medicine for arrhythmia. Some special compatibilities unreported were also discovered in the experiment, which may be used as the basis for developing new prescriptions for arrhythmia.

Static Recrystallization Behavior of SA508-III Steel during Hot Deformation

The static recrystallization behavior of SA508-III steel was investigated by isothermal double-hit hot compression tests at the deformation temperature of 950-1 250 ℃,the strain rate of 0. 01-1 s^（-1）,and the inter-pass time of 1-300 s.The effects of deformation parameters,including forming temperature,strain rate,degree of deformation（ pre-strain） and initial austenite grain size,on the softening kinetics were analyzed. Experimental results show that static recrystallization kinetics is strongly dependent on deformation temperature and degree of deformation,while less affected by the strain rate and initial grain size. The kinetics and microstructural evolution equations of static recrystallization for SA508-III steel were developed to predict the softening behavior and the statically recrystallized grain size,respectively. Based on the comparison between the experimental and predicted results,it is found that the established equations can give a reasonable estimate of the static softening behavior for SA508-III steel.

Chitosan based antibacterial composite materials for leather industry: a review

Chitosan is an amorphous translucent substance with a structural unit similar to the polysaccharide structure of the extracellular matrix,It has good antibacterial,biocompatible,and degradable properties.It has important application value in leather,water treatment,medicine,food and other fields,so chitosan and its modified products have received widespread attention.This article reviewed the preparation methods of chitosan-based antibacterial composites in recent years,including chitosan/collagen,chitosan/graphene,chitosan/tannic acid,and chitosan/polyethylene glycol composite materials,elaborates their modification methods and antibacterial mechanism were reviewed in detail,and its applications in the leather industry as antibacterial auxiliaries and water treatment antibacterial adsorption materials were discussed.Finally,the future development and challenges of chitosan-based composite materials in the leather industry were forecasted.