There are mainly four kinds of models to record and deal with historical information. By taking them as reference, the spatio-temporal model based on event semantics is proposed. In this model, according to the way fo...There are mainly four kinds of models to record and deal with historical information. By taking them as reference, the spatio-temporal model based on event semantics is proposed. In this model, according to the way for describing an event, all the information are divided into five domains. This paper describes the model by using the land parcel change in the cadastral information system, and expounds the model by using five tables corresponding to the five domains. With the aid of this model, seven examples are given on historical query, trace back and recurrence. This model can be implemented either in the extended relational database or in the object-oriented database.展开更多
Sound pressure amplitude will be attenuated with propagation distance in a certain rule when sound wave is propagated in shallow sea.When processing the attenuated signal,time-variant gain circuit is usually used to c...Sound pressure amplitude will be attenuated with propagation distance in a certain rule when sound wave is propagated in shallow sea.When processing the attenuated signal,time-variant gain circuit is usually used to compensate its diffusion loss.In this paper,spherical diffusion loss is compensated by digital potentiometer and operational circuit and further investigation is also made on compensation of cylindrical diffusion loss and transition from spherical diffusion loss to cylindrical diffusion loss.Finally,a new compensation model is proposed for unknown propagation loss for the purpose of adjusting the dynamic range of signal to meet the requirement of A/D conversion.展开更多
Based on real-time digital simulations(RTDS),a laboratory environment similar to the real-time operation situation of the Three Gorges Hydropower Station is established.Then,the causes for the power fluctuation of the...Based on real-time digital simulations(RTDS),a laboratory environment similar to the real-time operation situation of the Three Gorges Hydropower Station is established.Then,the causes for the power fluctuation of the second generator by errors in the rotor rotating speed calculation are found,and the tuning method of the speed related parameters are given.The damping and reverse tuning characteristics of power system stabilizers(PSSs)in the digital automatic voltage regulator(AVR)are compared and investigated in the frequency range of 0.18-1.1 Hz.The efficiency of the proposed tuning method for ensuring power system stability is verified by RTDS.Finally,field tests show the validity of the laboratory test results.展开更多
During the operation of complex process, such as oil production or refming, abnormal situations may occur, leading to an alarm flooding. Alarm flooding is the signalling of a large number of alarms in a few minutes, i...During the operation of complex process, such as oil production or refming, abnormal situations may occur, leading to an alarm flooding. Alarm flooding is the signalling of a large number of alarms in a few minutes, in such a way that it is impossible for the operator to attend to all alarms. On these occasions, it is usual that the operator leaves the alarm summary list and gets an analysis of the plant through the screens of the DCS （digital control system）, seeking to understand the situation. The alarm summary list ceases to be a useful tool. In such cases, the operator might have the aid of a filter that would present the highest priority alarms and other information associated with them, enabling him to gain a better knowledge of the situation. This paper describes the interface of a system aimed to help the operator to have a more comprehensive knowledge of the process （a better situational awareness） during process upsets that cause alarm flooding, recovering the utility of the alarm layer to the safety of industrial processes.展开更多
In the digital age, when we witness the rapid proliferation of platforms and services, European societies continue debating the role and the future of public service media （PSM）. In the new digital environment, publ...In the digital age, when we witness the rapid proliferation of platforms and services, European societies continue debating the role and the future of public service media （PSM）. In the new digital environment, public service broadcasting/media, which for a number of social and cultural reasons have been at the core of the European media system, faces the capital question--What democracy do public operators strive for and how can they accomplish it？ PSM has to be at the vanguard of the complex process of media transformation in the information society and particularly of the formation of novel journalistic culture which besides the values of ethical and innovative content should also serve the principles of good and efficient governance.展开更多
Let {Tn } be a renewal process in R＋ representing the successive arrival times of some natural events. We studied this process by using a record process approach under the assumption that the interarrival times T,, =...Let {Tn } be a renewal process in R＋ representing the successive arrival times of some natural events. We studied this process by using a record process approach under the assumption that the interarrival times T,, = Tn, - Ta-1, n = 1, 2...are exponentially i.i.d （independent and identically distributed）. The goal is to test that the first observed events are sporadic events. For testing the hypothesis ＂sporadic＂ we used the non-parametric test based on the probability distribution of the statistic of the number of records N, among{Xx }k-1= where Xk = （ΔTk）-1. We showed that it is independent of the cumulative distribution of the observations and that it is exactly calculated for each n. We illustrated this statistic on a simulated trajectory and we compared it with descriptive smoothing methods. We studied an application to a data set as storms in France and US.展开更多
In Chinese traditional culture, ceramic culture is a very special cultural system, With the advent of the era of network and the particularity of ceramic culture, Make the network native digital resources development ...In Chinese traditional culture, ceramic culture is a very special cultural system, With the advent of the era of network and the particularity of ceramic culture, Make the network native digital resources development and utilization is especially important. The idea of Web3.0 make important ceramic culture network native digital resources ＂reasonable configuration＂, t o be more embody the value of academic research. In this paper, we＇ll discuss the conformity utilization of ceramic culture native digital resources based on the concept of WEB3.0.展开更多
One of the significant differences between the digital system and the analog system is software. The software takes charge of the functions and the management of the digital system. Nowadays railway equipment has begu...One of the significant differences between the digital system and the analog system is software. The software takes charge of the functions and the management of the digital system. Nowadays railway equipment has begun to be designed and implemented based on digital technology with online and real time performance to achieve high speed and high density operation. The software is designed, coded and implemented into the system, and controls hardware components in order to satisfy the functional requirements of the system. As the functions that are implemented by software are increased, it becomes very difficult to predict the soil-ware failures because of its complexity. Therefore, it has become one of the key issues how to assure that the sottware is reliable, safe and secure. In this paper, the safety criteria are suggested to secure the software safety for the field of railway system. Characteristic of railway software and review safety related standards are analyzed. The authors also suggest development methodology and certification procedure for the developer and assessor to easily make safety critical railway software with following the safety criteria.展开更多
Communication networks rely on time synchronization information generated by base station equipment(either the Global Navigation Satellite System receiver or rubidium atomic clock) to enable wireless networking and co...Communication networks rely on time synchronization information generated by base station equipment(either the Global Navigation Satellite System receiver or rubidium atomic clock) to enable wireless networking and communications. Meanwhile, the time synchronization among base stations depends on the Network Time Protocol. With the development of mobile communication systems, the corresponding time synchronization accuracy has increased as well. In this case, the use of sparsely distributed-high-precision synchronization points to synchronize time for an entire network with high precision is a key problem and is the foundation of the enhanced network communication. The current receiver equipment for China's digital synchronous network typically includes dedicated multi-channel GPS receivers for communication; however, with the development of GPS by the USA, network security has been destabilized and reliability is low. Nonetheless, network time synchronization based on Beidou satellite navigation system timing devices is an inevitable development trend for China's digital communications network with the establishment of the independently developed BDS, especially the implementation and improvement of the Beidou foundation enhancement system.展开更多
文摘There are mainly four kinds of models to record and deal with historical information. By taking them as reference, the spatio-temporal model based on event semantics is proposed. In this model, according to the way for describing an event, all the information are divided into five domains. This paper describes the model by using the land parcel change in the cadastral information system, and expounds the model by using five tables corresponding to the five domains. With the aid of this model, seven examples are given on historical query, trace back and recurrence. This model can be implemented either in the extended relational database or in the object-oriented database.
文摘Sound pressure amplitude will be attenuated with propagation distance in a certain rule when sound wave is propagated in shallow sea.When processing the attenuated signal,time-variant gain circuit is usually used to compensate its diffusion loss.In this paper,spherical diffusion loss is compensated by digital potentiometer and operational circuit and further investigation is also made on compensation of cylindrical diffusion loss and transition from spherical diffusion loss to cylindrical diffusion loss.Finally,a new compensation model is proposed for unknown propagation loss for the purpose of adjusting the dynamic range of signal to meet the requirement of A/D conversion.
文摘Based on real-time digital simulations(RTDS),a laboratory environment similar to the real-time operation situation of the Three Gorges Hydropower Station is established.Then,the causes for the power fluctuation of the second generator by errors in the rotor rotating speed calculation are found,and the tuning method of the speed related parameters are given.The damping and reverse tuning characteristics of power system stabilizers(PSSs)in the digital automatic voltage regulator(AVR)are compared and investigated in the frequency range of 0.18-1.1 Hz.The efficiency of the proposed tuning method for ensuring power system stability is verified by RTDS.Finally,field tests show the validity of the laboratory test results.
文摘During the operation of complex process, such as oil production or refming, abnormal situations may occur, leading to an alarm flooding. Alarm flooding is the signalling of a large number of alarms in a few minutes, in such a way that it is impossible for the operator to attend to all alarms. On these occasions, it is usual that the operator leaves the alarm summary list and gets an analysis of the plant through the screens of the DCS （digital control system）, seeking to understand the situation. The alarm summary list ceases to be a useful tool. In such cases, the operator might have the aid of a filter that would present the highest priority alarms and other information associated with them, enabling him to gain a better knowledge of the situation. This paper describes the interface of a system aimed to help the operator to have a more comprehensive knowledge of the process （a better situational awareness） during process upsets that cause alarm flooding, recovering the utility of the alarm layer to the safety of industrial processes.
文摘In the digital age, when we witness the rapid proliferation of platforms and services, European societies continue debating the role and the future of public service media （PSM）. In the new digital environment, public service broadcasting/media, which for a number of social and cultural reasons have been at the core of the European media system, faces the capital question--What democracy do public operators strive for and how can they accomplish it？ PSM has to be at the vanguard of the complex process of media transformation in the information society and particularly of the formation of novel journalistic culture which besides the values of ethical and innovative content should also serve the principles of good and efficient governance.
文摘Let {Tn } be a renewal process in R＋ representing the successive arrival times of some natural events. We studied this process by using a record process approach under the assumption that the interarrival times T,, = Tn, - Ta-1, n = 1, 2...are exponentially i.i.d （independent and identically distributed）. The goal is to test that the first observed events are sporadic events. For testing the hypothesis ＂sporadic＂ we used the non-parametric test based on the probability distribution of the statistic of the number of records N, among{Xx }k-1= where Xk = （ΔTk）-1. We showed that it is independent of the cumulative distribution of the observations and that it is exactly calculated for each n. We illustrated this statistic on a simulated trajectory and we compared it with descriptive smoothing methods. We studied an application to a data set as storms in France and US.
文摘In Chinese traditional culture, ceramic culture is a very special cultural system, With the advent of the era of network and the particularity of ceramic culture, Make the network native digital resources development and utilization is especially important. The idea of Web3.0 make important ceramic culture network native digital resources ＂reasonable configuration＂, t o be more embody the value of academic research. In this paper, we＇ll discuss the conformity utilization of ceramic culture native digital resources based on the concept of WEB3.0.
文摘One of the significant differences between the digital system and the analog system is software. The software takes charge of the functions and the management of the digital system. Nowadays railway equipment has begun to be designed and implemented based on digital technology with online and real time performance to achieve high speed and high density operation. The software is designed, coded and implemented into the system, and controls hardware components in order to satisfy the functional requirements of the system. As the functions that are implemented by software are increased, it becomes very difficult to predict the soil-ware failures because of its complexity. Therefore, it has become one of the key issues how to assure that the sottware is reliable, safe and secure. In this paper, the safety criteria are suggested to secure the software safety for the field of railway system. Characteristic of railway software and review safety related standards are analyzed. The authors also suggest development methodology and certification procedure for the developer and assessor to easily make safety critical railway software with following the safety criteria.
文摘Communication networks rely on time synchronization information generated by base station equipment(either the Global Navigation Satellite System receiver or rubidium atomic clock) to enable wireless networking and communications. Meanwhile, the time synchronization among base stations depends on the Network Time Protocol. With the development of mobile communication systems, the corresponding time synchronization accuracy has increased as well. In this case, the use of sparsely distributed-high-precision synchronization points to synchronize time for an entire network with high precision is a key problem and is the foundation of the enhanced network communication. The current receiver equipment for China's digital synchronous network typically includes dedicated multi-channel GPS receivers for communication; however, with the development of GPS by the USA, network security has been destabilized and reliability is low. Nonetheless, network time synchronization based on Beidou satellite navigation system timing devices is an inevitable development trend for China's digital communications network with the establishment of the independently developed BDS, especially the implementation and improvement of the Beidou foundation enhancement system.
