一种新型的交流稳压电源

提出一种新型的交流稳压电源,采用直接的“交流/交流”的变换电路和PWM控制。该稳压电源电路简单可靠、稳压性能好,对由高次谐波产生的纹波亦有很好的抑制作用。

Research on a non-linear chaotic prediction model for urban traffic flow

In order to solve serious urban transport problems, according to the proved chaotic characteristic of traffic flow, a non linear chaotic model to analyze the time series of traffic flow is proposed. This model reconstructs the time series of traffic flow in the phase space firstly, and the correlative information in the traffic flow is extracted richly, on the basis of it, a predicted equation for the reconstructed information is established by using chaotic theory, and for the purpose of obtaining the optimal predicted results, recognition and optimization to the model parameters are done by using genetic algorithm. Practical prediction research of urban traffic flow shows that this model has famous predicted precision, and it can provide exact reference for urban traffic programming and control.

Car-following models of vehicular traffic

The Car-following models is a kind of microscopic simulation model for vehicular traffic, which describe the one-by-one following behaviors of vehicles in the same traffic lane. As a common traffic phenomenon, following behavior is of great importance in the micro-study of intelligent traffic control. Compared with other traffic-flow models, car-following model embodies the human factors and reflects the real traffic situation in a better way. This paper gives a systematic review of the development and actuality of car-following models by introducing and analyzing in detail the advantages and disadvantages of GHR model, OV model, CA model and fuzzy-logic model. In addition, local stability and asymptotic stability of car-following models are discussed in this paper.

Terminal Traffic Flow Prediction Method Under Convective Weather Using Deep Learning Approaches

In order to improve the accuracy and stability of terminal traffic flow prediction in convective weather,a multi-input deep learning(MICL)model is proposed.On the basis of previous studies,this paper expands the set of weather characteristics affecting the traffic flow in the terminal area,including weather forecast data and Meteorological Report of Aerodrome Conditions(METAR)data.The terminal airspace is divided into smaller areas based on function and the weather severity index(WSI)characteristics extracted from weather forecast data are established to better quantify the impact of weather.MICL model preserves the advantages of the convolution neural network(CNN)and the long short-term memory(LSTM)model,and adopts two channels to input WSI and METAR information,respectively,which can fully reflect the temporal and spatial distribution characteristics of weather in the terminal area.Multi-scene experiments are designed based on the real historical data of Guangzhou Terminal Area operating in typical convective weather.The results show that the MICL model has excellent performance in mean squared error(MSE),root MSE(RMSE),mean absolute error(MAE)and other performance indicators compared with the existing machine learning models or deep learning models,such as Knearest neighbor(KNN),support vector regression(SVR),CNN and LSTM.In the forecast period ranging from 30 min to 6 h,the MICL model has the best prediction accuracy and stability.

On preferred and dispreferred second turns in interaction

Conversation analysis （CA） is an integral part of the study of language in communication, in which preference organization is an important topic for pragmatic research. This paper makes a study of preferred and dispreferred second turns in naturally occurring interactions to show structurally expected or unexpected responses from the second parts of the adjacent pairs. The study is based on the analysis of examples of people＇s actual conversations. It is concluded that in actual conversations, the speaker may make a preferred or dispreferred answer in either marked or unmarked form according to the speaker＇s intention and conversation circumstances.

Study of the Relationship Between the Organizational Climate and the Campus Ethical Issues of Universities across the Taiwan Strait

The study applied the approach of empirical studies to select 176 teachers in 9 universities in Taiwan and Inland in China to deliver questionnaires. The study intended to explore the influence of organizational climate on campus ethics and its diversity between the universities across the Taiwan strait. The study explored that the organizational climate in the universities across the Strait was not ethically high. Yet, the universities in Inland emphasized more on campus restraint in teachers behavior, job performance and their sense of belonging to the school.The study result demonstrated that improving leadership of the universities could enhance teachers identification with their schools and could promote the level of campus across the Strait.

Research on the variable speed system of large power alternating current motor

The development status of the variable speed system of large power AC(alternating current)motor drive in China is introduced.The large power AC drive fed by AC-AC converters(cycloconverters)has developed greatly,and some innovations on the theory and engineering technique have been realized.They have been applied to rolling mills,mine hoists,and so on,and remarkable economic and social benefit has been achieved.The development of AC drive fed by large power IGCT(integrated gate commutated thyristors)AC-DC-AC converter is also introduced.It has excellent performance and reliable operation,and has been used in traction.

Effect of Surface Charge on Flashover for Oil-Pressboard Insulation under AC-DC Combined Electric Field

For converter transformer, AC-DC combined electric field can trigger space charge accumulation on oil-impregnated pressboard interface. The accumulation of space charge on oil-pressboard interface can result in electric field distortion, trend to trigger surface discharge of barriers. This paper studied the influence of surface charge on flashover voltage of oil-impregnated pressboard under AC-DC combined electric field. The study finds that the flashover voltage of oil-pressboard interface under negative polarity DC superimposed AC electric field is higher than that.of positive DC superimposed AC voltage to form composite electric field. It was found that homopolar surface charge has been accumulated on the interface of oil-pressboard with positive or negative DC voltage through measuring surface potential by the electrostatic capacitive probe. The surface charge produced electric field in the opposite direction, which weakening the synthetic electric field strength. What＇s more, under the same conditions, the negative surface charge density oil-pressboard is much larger than the positive.

Research on General Financial Message Standards and Their Application

New challenges have been posed to the infornmtion exchange and interconn,u;fion in financial industry with the innovalion of financial business and the development of infarmation techtinlogy. From the perspective of financial message standardization. ISO 20022 puts forward a set of sohaions and ideas for information exchange, which have been recognized in financiat industry all around the world. Considering the variety of financial message standards and message exchange modes, it is essential to strengthen the development and application of general message standards for financial industry and build：up the general m^sage exchange platform, which wild play a significant role in guiding lhe slandardized developmenl of industry, implementing financial s/andardizalion slralegies, and enhancing the level of inlerconneclion.

High-Performance AC-DC Power Electronic Converter Generator for Hybrid-Solar Vehicles

This paper describes the principles of operation and the physical model of an advanced AC-DC converter generator （with the electronic converter acting as an AC-DC rectifier with reverse-conducting MOSFETs （metal-oxide semiconductor field-effect transistors） as fast-electronic switches with a relatively low ON-state voltage drop） for HSVs. An AC-DC converter, when seen as an AC-DC rectifier, can be used in many fields, e.g., for multi-functional AC-DC/DC-AC convener generator^starter and conventional DC-AC convener motors and AC-DC converter generators or generator sets, welding machines, etc. The paper also describes a novel AC-DC convener, with reverse-conducting transistors and without the use of optoelectronic separation （which does not require a separate power supply）, which may be easily realized in IC （integrated-circuit） technology. Computer simulation allows for waveform evaluation for timing analysis of all components of the AC-DC-converter＇s physical model, both during normal operation as well as in some states of emergency. The paper also presents the results of bench experimental studies where the MOSFETs were used as fast-electronic switches with a relatively low ON-state voltage drop. For experimental studies, a novel AC-DC converter has been put together on the Mitsubishi FM600TU-3A module. The AC-DC converter with reverse-conducting transistors in a double-way connection has a lot of advantages compared to the conventional AC-DC convener acting as a diode rectifier, such as higher energy efficiency and greater reliability resulting from the lower temperature of electronic switches.

FACE-TO-FACE AND SYNCHRONOUS ELECTRONIC DISCUSSION AS PREWRITING ACTIVITY IN THE FOREIGN LANGUAGE WRITING CLASS

One of the main findings of computer-mediated communication study in recent years is that it has anequalizing effect among student participation in class. Face-to-face discussions tend to be relatively unbalanced,with the teacher or a few participants dominating the floor; however, computer-mediated communicationfeatures more balanced participation, with participants sharing the floor more equally. According to somestudies, second and foreign language teachers have also claimed that electronic communication has been provedto be an equalizer in their classrooms. Besides, some researches find that the formality and complexity oflanguage in electronic discussion might be an excellent medium for prewriting work since it could serve as abridge from spoken interaction to written composition. This study aims to prove these claims throughcomparing the performances of student participation in the traditional face-to-face prewriting small groupdiscussions and those in the synchronous computer-mediated communication mode. The findings show out atendency toward more equal participation in computer-mediated communication mode. The study alsodiscovers that the language students used in the electronic prewriting discussion and in the first drafts composedafter the discussion is more formal and complex lexically and syntactically than the language they used in face-to-face mode. The comparison of the first drafts which were finished separately after the two modes ofdiscussion by individual student demonstrate, however, there is not obvious differences among the twocategories of first drafts concerning the content of writing.