Unified Smith Predictor Based H_∞ Wide-Area Damping Controller to Improve the Control Resiliency to Communication Failure

Inter-area low frequency oscillation in power system is one of the major problems for bulk power transmission through weak tie lines.Use of wide-area signal is more effective than the local area signal in damping out the inter-area oscillations.Wide area measurement system(WAMS)is convenient to transmit the wide area signal through the communication channel to the remote location.Communication failure is one of the disastrous phenomena in a communication channel.In this paper,a dual input single output(DISO)Hm controller is designed to build the control resiliency by employing two highest observability ranking wide area signals with respect to the critical damping inter-area mode.The proposed controller can provide sufficient damping to the system and also the system remains stabilized if one of the wide-area signals is lost.The time delay is an unwanted phenomenon that degrades the performance of the controllers.The unified Smith predictor approach is used to design a Hm controller to handle the time delay.Kundur's two-area and IEEE-39 bus test systems are considered to verify the effectiveness of the proposed controller.From the simulation results,it is verified that,the proposed controller provides excellent damping performance at normal communication and improves the controller resiliency to counteract the communication failure.

Intercultural Communication Failure： A Case Study

The paper makes a case study of the intercultural communication failure, which is caused by the presence of stereotypes and preconceptions. It analyzes the communication problems with Hyme＇s SPEAKING framework. From the analysis, it is concluded, that individuals who hope to carry out effective intercultural interaction must learn to understand the expectations and preconceptions of those they want to talk with.

A Delay-dependent Dynamic Wide Area Damping Controller for Renewable Energy Integrated Power System Resilient to Communication Failure

Integration of renewable energy sources(RES)with a conventional power system has a detrimental effect on interarea oscillation.Most popular RESs are solar photovoltaic(PV)and wind energy conversion systems(WECS).Both solar PV power generation and WECS are integrated with power systems using a power electronic converter.Increasing the amount of RES generation lead towards reduction of system damping,which leads towards inter-area oscillation.Also,the intermittent behavior of a RES reduces the effectiveness of damping controllers.A dynamic controller based wide area damping controller(WADC)is proposed in this paper to increase small signal stability of a RES integrated power system.The WADC is designed for contemplating delay in a communication channel,communication failure and saturation.An anti-windup compensator is developed to overcome the effect of actuator saturation.However,the gain of the anti-windup compensator is calculated using LyapunovKrasovskii functional(LKF)in terms of linear matrix inequality(LMI).The actuator considered in this paper is a unified power flow controller(UPFC).Efficacy of PV and wind power integration on power system is also observed.The efficacy of the developed dynamic controller is verified using IEEE 39 bus and 68 bus power system.

Stability of connected and automated vehicles platoon considering communications failures

As a form of a future traffic system,a connected and automated vehicle(CAV)platoon is a typical nonlinear physical system.CAVs can communicate with each other and exchange information.However,communication failures can change the platoon system status.To characterize this change,a dynamic topology-based car-following model and its generalized form are proposed in this work.Then,a stability analysis method is explored.Finally,taking the dynamic cooperative intelligent driver model(DC-IDM)for example,a series of numerical simulations is conducted to analyze the platoon stability in different communication topology scenarios.The results show that the communication failures reduce the stability,but information from vehicles that are farther ahead and the use of a larger desired time headway can improve stability.Moreover,the critical ratio of communication failures required to ensure stability for different driving parameters is studied in this work.

The Necessity of Cultural Elements in ESL Teaching --Through the Analysis of the Pragmatic Failure in Cross-cultural Communication

It is undeniable that it is difficult for Chinese English learners to communicate competently in English with native English speakers. Compared with the grammar mistakes, the pragmalinguistic failures and sociopragmatic failures are subtle and have received less attention from Chinese English learners. Misunderstanding caused by cross-cultural pragmatic differences is the source of cross-cultural communication breakdown and therefore much more attention should be paid to our communication. The article concerns the failures occurred in cross-cultural communication to show the importance of cross-cultural awareness in the successful communication.

Analysis of Pragmatic Failure and College English Teaching

This article uses a lot of evidences to expose the pragmatic failures in people＇s inter-cultural communication, and analyses the types and causes of these pragmatic failures. Hence it puts forward several methods of college English teaching to help our students get rid of such pragmatic failures.

Pragmalinguistic Failure and English Language Teaching

This paper probes how to foster Chinese English learners＇ pragmalinguistic competence through classroom instruction, thus reducing the occurrence of pragmalinguistic failure and improving learners＇ communicative competence.

Survey of High School English Teachers＇ Pragmatic Failure

According to the principals of the Course Standard of English for Ordinary Senior Schools, published by China Education Ministry in 2001, the general goal of English curriculum on the basic education stage is to foster the students＇ cross-cultural awareness, which is to develop their cross-cultural communicative competence. To achieve this goal, most of all, teachers of English at high school must have a good command of cross-cultural pragmatic competence. By looking through papers in various periodicals and the Internet, the writer finds that most of the studies have coped with pragmatic failures of ESL students but few of ESL teachers＇. Therefore, this thesis studies the present situation --- how much do schoolteachers of English know about pragmatics？ What about their cross-cultural communicative competence？ Can they communicate with the native speakers fluently and appropriately？ What are the most serious problems among them in pragmatics？ What can be done to solve the problems？ With all the questions, this research has collected considerable firsthand data and information. Only after the basic situations are known overall, can actions be taken to solve the problems existing in everyday ESL teaching. So this research is necessary and urgent for the present basic English pedagogy. However, since the present writer＇s ability and research conditions are limited, it is not possible to make a wider investigation in many places. Therefore, the district --- Bameng League, Inner Mongolia, China, is selected as the basic range of the survey, the situation of which is believed to be able to represent the basic educational ones in the poor and remote districts in the north and the west of China where education is more backward. The questionnaire consists of two parts： a table of individual information and a test paper. The former investigates informants＇ basic information, including the items of name, age, sex, teaching age, title of the technical post, degree, academic career, college or university that they graduated from, working unit, grades for teaching and the others. The latter is the test paper cited from He Ziran and Yan Zhuang （1986）, that is, Chinese Students＇Pragmatic Failure in English Communication --- Survey of the Pragmatic Difference between Chinese and English. And it contains 48 items, with items of pragmalinguistic and socio-pragmatic competence mixedly arranged. 120 of the questionnaire copies were handed out and 86 are collected, but only 64 are collected. The survey covers over 10 high schools in all the 7 banners of Bameng League, including two autonomous region-class key schools and five other league-class key schools. After the investigation, the present writer carefully corrects, marks, arranges, summarizes and analyzes the questionnaire, and obtains plenty of firsthand data and information. Then some conclusions have been drawn based on the data analysis. The result of the survey shows that linguistic competence is not equal to pragmatic competence, that ESL high school English teachers may use English rather fluently, without many mistakes in vocabulary and grammar,but it does not necessarily mean that they can use the target language appropriately to communicate with native speakers without pragmatic failures, and that the informants＇ knowledge of pragmatics and their pragmatic competence are rather poor. As a result, improving their knowledge and competence in pragmatics becomes a very necessary and urgent task to develop the quality of ELT in basic educational stages. In order to solve the above problems, the writer makes some suggestions as follows： （1） Pragmatics should be required as an essential course for the English majors in colleges and universities, especially in normal colleges and universities; （2） In-service high school English teachers must study courses of pragmatics and cross-cultural communication; （3） In some poor and remote districts, if educational conditions don＇t permit, textbooks of pragmatics and cross-cultural communication must be handed out to the high school English teachers who can study by themselves, then tests are regularly held for them and certificates will be given to those who have passed the tests; （4） In some developed districts, if conditions permit, English teachers can be sent abroad to English-speaking countries for further education in order to have a good command of the English language in the authentic contexts; （5） Modern multiple medias, such as VCD or DVD videos, TV or radio programs, the Internet, should be widely and frequently applied to training teachers; （6） More native language teachers and experts from English-speaking countries must be invited to high schools to train teachers of English.

A fully distributed robust optimal control approach for air-conditioning systems considering uncertainties of communication link in IoT-enabled building automation systems

Internet of Things(IoT)technologies are increasingly implemented in buildings as the cost-effective smart sens-ing infrastructure of building automation systems(BASs).They are also dispersed computing resources for novel distributed optimal control approaches.However,wireless communication networks are critical to fulfill these tasks with the performance influenced by inherent uncertainties in networks,e.g.,unpredictable occurrence of link failures.Centralized and hierarchical distributed approaches are vulnerable against link failure,while the robustness of fully distributed approaches depends on the algorithms adopted.This study therefore proposes a fully distributed robust optimal control approach for air-conditioning systems considering uncertainties of com-munication link in IoT-enabled BASs.The distributed algorithm is adopted that agents know their out-neighbors only.Agents directly coordinate with the connected neighbors for global optimization.Tests are conducted to test and validate the proposed approach by comparing with existing approaches,i.e.,the centralized,the hierarchical distributed and the fully distributed approaches.Results show that different approaches are vulnerable against to uncertainties of communication link to different extents.The proposed approach always guarantees the optimal control performance under normal conditions and conditions with link failures,verifying its high robustness.It also has low computation complexity and high optimization efficiency,thus applicable on IoT-enabled BASs.

Detecting and Locating Failures in Communication Networks

The connectivity of a strongly connected network may be destroyed after link damage.Since many net- works are connected by directed links,the reachability may be restored by altering the direction of one or more of the links and thus reconfigoring the network.The location of the failed link must first be determined.In this paper,we examine new methods to determine the location of failed links and nodes in networks.A routing test approach is proposed and the conditions under which communication networks may be tested are discussed. Finally,an adaptive algorithm and a heuristic algorithm that can locate a single failed llnk or a single failed node are presented.

Relaxed Alternating Direction Method of Multipliers for Hedging Communication Packet Loss in Integrated Electrical and Heating System

Integrated electrical and heating systems(IEHSs)are promising for increasing the flexibility of power systems by exploiting the heat energy storage of pipelines.With the recent development of advanced communication technology,distributed optimization is employed in the coordination of IEHSs to meet the practical requirement of information privacy between different system operators.Existing studies on distributed optimization algorithms for IEHSs have seldom addressed packet loss during the process of information exchange.In this paper,a distributed paradigm is proposed for coordinating the operation of an IEHS considering communication packet loss.The relaxed alternating direction method of multipliers(R-ADMM)is derived by applying Peaceman-Rachford splitting to the Lagrangian dual of the primal problem.The proposed method is tested using several test systems in a lossy communication and transmission environment.Simulation results indicate the effectiveness and robustness of the proposed R-ADMM algorithm.

Safety benefit of cooperative control for heterogeneous traffic on-ramp merging

The safety of heterogeneous traffic is a vital topic in the oncoming era of autonomous vehicles(AVs).The cooperative vehicle infrastructure system(CVIS)is considered to improve heterogeneous traffic safety by connecting and controlling AVs cooperatively,and the connected AVs are so-called connected and automated vehicles(CAVs).However,the safety impact of cooperative control strategy on the heterogeneous traffic with CAVs and human-driving vehicles(HVs)has not been well investigated.In this paper,based on the traffic simulator SUMO,we designed a typical highway scenario of on-ramp merging and adopted a cooperative control method for CAVs.We then compared the safety performance for two different heterogeneous traffic systems,i.e.AV and HV,CAV and HV,respectively,to illustrate the safety benefits of the cooperative control strategy.We found that the safety performance of the CAV and HV traffic system does not always outperform that of AV and HV.With random departSpeed and higher arrival rate,the proposed cooperative control method would decrease the conflicts significantly whereas the penetration rate is over 80%.We further investigated the conflicts in terms of the leading and following vehicle types,and found that the risk of a AV/CAV followed by a HV is twice that of a HV followed by another HV.We also considered the safety effect of communication failure,and found that there is no significant impact until the packet loss probability is greater than 30%,while communication delay’s impact on safety can be ignored according to our experiments.