KINEMATICAL ANALYSIS OF DISMOUNT OF STRAIGHT BACK SOMERSAULT WITH A TURN OF 900° : A CASE STUDY

The techniques of dismount of straight back somersault with a turn of 900° performed by Tan Sixin (winner of all-round of China's gymnastics championships in 2011) and Jiang Yuyuan(winner of champion of the balance beam of World University Games in 2009) was filmed using 3-D camera method. The kinematics data were collected and analyzed by motion performance analysis system. The conclusions came out that overall execution of Tan Sixin was good, while the action of Jiang Yuyuan needed to be improved. The results of the analysis will provide a theoretical basis of balance beam training for athletics and trainer

Essays in Information Transmission and Institution Design

This thesis consists of three essays in information transmission and institution design. Chapter 1 constructs a model of information transmission. The model was set up with an informed sender and two uninformed receivers, where the sender wants to convince the receivers to take a certain action. We analyze strategic information transmission model with two parameters, one is different levels of persuasive function of the channels; another is different degrees of connection between the receivers. We show that if persuasive function is a linear or convex function, the sender should invests all expenditure to one channel with higher level of persuasive function and higher degree of information transmission of the receiver; while if persuasive function is a concave function, three possible optimal behaviours of the sender are investing to one channel, both channels equally, or both channels unequally. Given two concave function examples, we show some decision rules for the sender’s optimal expenditure allocation. Specifically, we show that it is not always to allocate expenditure in both channels equally in symmetric model; it is always to invest all expenditure to only one channel when another channel has very low level of persuasive function, or very low degree of connection between the receivers, and it is always to increase expenditure in one channel when the degree of information transmission of the corresponding receiver increases in asymmetric model. Chapter 2 studies two scenarios in a formal analysis of scientists’ effort provision in research and dissemination. One is a simultaneous problem that the sender offers effort to send signal to two types of audiences, such as experts and public; another is a sequential problem that the sender offers effort in academic research, and then sends signal to one type of audiences to representation with effort in science popularization. We investigate how the scientist should divide their time or energy between academic research and science popularization to obtain maximum utility. Consider the same probability and different probability functions at two dimensional for each scenario. We show the optimal allocation of effort depends on the weight of payoff from academic research and science popularization, and the difference in two probability functions between two signals, or between signal and representation. Specifically, in scenario one, if there exist polarization in academic research and science popularization, we could prevent polarization by increasing the ratio of the weights of payoff from dissemination and research using incentives to guarantee the scientist keep the allocation of effort as before. In scenario two, the result shows that we should put equal effort on research and dissemination for scientific achievements transformation no matter how difference in two probability functions between signal and representation. Chapter 3 constructs a simple model of direct democracy with supermajority rule and different preference intensities for two sides of a referendum: reform versus status quo. Two parties spend money and effort to mobilize their voters. We characterize the set of pure strategy Nash equilibria. We investigate the optimal majority rule that maximizes voters’ welfare. Using an example, we show that if the preference intensity of the status quo side is relatively high, the higher preference intensity of the status quo side, the higher the optimal majority rule. While, if the preference intensity of status quo side is relatively low, the optimal majority rule decreases if the preference intensity of the status quo side increases. We also show that when the preference intensity of the status quo side is higher, or the easiness to mobilize voters on the status quo side is lower, the optimal majority rule is more likely to be supermajority

Secure and Efficient Dynamic Spectrum Access Solutions for Future Wireless Networks

University of Technology Sydney. Faculty of Engineering and Information Technology.The future wireless communication network (5G and beyond) is expected to provide many advantages, such as an extremely high peak rate, ultralow latency and less energy consumption. However, since an extremely large number of connecting devices will be deployed, the demand for the spectrum will also be growing exponentially, causing a problem of spectrum shortage. To effectively address the spectrum crunch, dynamic spectrum access (DSA), including both sensing-based and database-driven DSA, has been proposed. In this thesis, we investigate critical challenges in DSA, including the efficiency in sensing-based techniques and privacy in database-driven techniques. First, to improve the sensing performance of the sensing-based DSA in half-duplex (HD) systems, we propose two sensing approaches leveraging the property of deep learning networks. Our solutions are significantly superior in terms of the robustness to noise uncertainty, timing delay, and carrier frequency offset (CFO), compared to conventional sensing methods. Moreover, our work does not require any prior information of signals, which however is essential for the traditional sensing methods. Second, to improve the sensing performance of sensing-based DSA in full-duplex (FD) systems, we develop two novel sensing methods using the features of orthogonal frequency division multiplexing (OFDM) signals. The developed sensing approaches are robust to not only residual SI but also timing delay or CFO. We also obtain the closed-form expressions of the probability of detection and false alarm for our approaches. Third, to protect the users' privacy in the database-driven DSA, we develop two schemes to protect the operational privacy of Incumbent Users (IUs) and honest/dishonest Secondary Users (SUs). To implement our proposed work, we introduce an interference calculation scheme that allows users to calculate an interference budget without revealing operational information. It also reduces the computing overhead of our developed approaches. Additionally, we propose a “punishment and forgiveness” mechanism to encourage dishonest SUs to provide truthful information. Theoretical analysis and extensive simulations show that our proposed schemes can better protect all users’ operational privacy under various privacy attacks, yielding higher spectrum utilization with less online overhead, compared with state of the art approaches

The Active and Reactive Power Dispatch for Charging Station Location Impact Factors Analysis

With the increasing number of Electric Vehicles (EVs) in modern society, a number of challenges and opportunities are presenting themselves. For example, how to choose charging station locations to minimize the Distribution Network's (DN) power loss when a large number of EVs are connected to the DN. How impact factors, such as different load patterns, EVs’ charging locations and network topology, affect charging station location is becoming vital. In this paper a new charging station location methodology informed by impact factor analysis is proposed by using the Active and Reactive Power Dispatch of charging stations in terms of power loss minimization. Results for the 36 DN with three different scenarios are presented. In addition, a more realistic model based on EV's daily travel patterns is built to illustrate how these impact factors affect charging station location. It is demonstrated that the optimal charging station location in terms of power loss minimization can be found by using the new methodology, and it is not affected by the EVs’ charging location and load patterns, it is affect by the network topology

Robust Weighted Sum-Rate Maximization for Transmissive RIS Transmitter Enabled RSMA Networks

Due to the low power consumption and low cost nature of transmissive reconfigurable intelligent surface (RIS),in this paper, we propose a downlink multi-user rate-splitting multiple access (RSMA) architecture based on the transmissive RIS transmitter, where the channel state information (CSI) is only accquired partially. We investigate the weighted sum-rate maximization problem by jointly optimizing the power, RIS transmissive coefficients and common rate allocated to each user. Due to the coupling of optimization variables, the problem is nonconvex, and it is difficult to directly obtain the optimal solution. Hence, a block coordinate descent (BCD) algorithm based on sample average approximation (SAA) and weighted minimum mean square error (WMMSE) is proposed to tackle it. Numerical results illustrate that the transmissive RIS transmitter with ratesplitting architecture has advantages over conventional space division multiple access (SDMA) and non-orthgonal multiple access (NOMA)