Towards Secure Deep Neural Networks for Cyber-Physical Systems

In recent years, deep neural networks (DNNs) are increasingly investigated in the literature to be employed in cyber-physical systems (CPSs). DNNs own inherent advantages in complex pattern identifying and achieve state-of-the-art performances in many important CPS applications. However, DNN-based systems usually require large datasets for model training, which introduces new data management issues. Meanwhile, research in the computer vision domain demonstrated that the DNNs are highly vulnerable to adversarial examples. Therefore, the security risks of employing DNNs in CPSs applications are of concern. In this dissertation, we study the security of employing DNNs in CPSs from both the data domain and learning domain. For the data domain, we study the data privacy issues of outsourcing the CPS data to cloud service providers (CSP). We design a space-efficient searchable symmetric encryption scheme that allows the user to query keywords over the encrypted CPS data that is stored in the cloud. After that, we study the security risks that adversarial machine learning (AML) can bring to the CPSs. Based on the attacker properties, we further separate AML in CPS into the customer domain and control domain. We analyze the DNN-based energy theft detection in advanced meter infrastructure as an example for customer domain attacks. The adversarial attacks to control domain CPS applications are more challenging and stringent. We then propose ConAML, a general AML framework that enables the attacker to generate adversarial examples under practical constraints. We evaluate the framework with three CPS applications in transportation systems, power grids, and water systems. To mitigate the threat of adversarial attacks, more robust DNNs are required for critical CPSs. We summarize the defense requirements for CPS applications and evaluate several typical defense mechanisms. For control domain adversarial attacks, we demonstrate that defensive methods like adversarial detection are not capable due to the practical attack requirements. We propose a random padding framework that can significantly increase the DNN robustness under adversarial attacks. The evaluation results show that our padding framework can reduce the effectiveness of adversarial examples in both customer domain and control domain applications

Empires of Knowledge: Chinese Students’ higher education experience at X University, UK

I discuss the difficulties Chinese international students (CIS) met in their UK higher education and how far their understanding of knowledge has been transformed by such experience from field research conducted at X University, UK, from 2017 to 2020. First, I flesh out the theoretical framework for the thesis: a view of power and knowledge influenced by Foucault and the interpretation of Chinese and western cultures in Sino-Hellenic studies. Second, I review the anthropological work on education, knowledge, and CIS to situate the basis and goals of the thesis. Third, I explore how legacies of thought in ancient and modern China and the transformation of higher education in the UK have influenced CIS’ overseas study. Fourth, I explore CIS’ life and social networking at X University, UK. Fifth, I explore CIS’ classroom learning experiences. I argue that students’ different reactions and attitudes toward the perceived confusion in classroom learning represent a collision between two ways of knowing: the traditional Chinese “sage style” and the Western “post-modern critical style”. Sixth, I explore research CIS’ study experience and demonstrate that the British and Chinese ways of PhD training suit students based on the specific experience of individuals. CIS still favour the “master’s family” tradition in Chinese research degree training after they studied in the UK. Seventh, I explore CIS’ academic writing practice in the UK. I illustrate that the difficulties they experience in UK academic writing could be explained by the different patterns of thought and ways of communication or persuasion in the two cultures. I also present the third way of knowing which CIS are exposed: the “objectivistic” Western natural science style. I conclude that though modern Western natural science’s way of knowing is the dominant knowledge style today in China and the UK, it also has its limitations. A hegemonic “empire of knowledge” deserves to be reflected on, criticised, and replaced by “exchanges and mutual learning” to inject fresh impetus into the development of human knowledge

A Practical Searchable Symmetric Encryption Scheme for Smart Grid Data

Outsourcing data storage to the remote cloud can be an economical solution to enhance data management in the smart grid ecosystem. To protect the privacy of data, the utility company may choose to encrypt the data before uploading them to the cloud. However, while encryption provides confidentiality to data, it also sacrifices the data owners' ability to query a special segment in their data. Searchable symmetric encryption is a technology that enables users to store documents in ciphertext form while keeping the functionality to search keywords in the documents. However, most state-of-the-art SSE algorithms are only focusing on general document storage, which may become unsuitable for smart grid applications. In this paper, we propose a simple, practical SSE scheme that aims to protect the privacy of data generated in the smart grid. Our scheme achieves high space complexity with small information disclosure that was acceptable for practical smart grid application. We also implement a prototype over the statistical data of advanced meter infrastructure to show the effectiveness of our approach

Različiti utjecaji latentne topline u planetarnom graničnom sloju i mikrofizičkih procesa u oblacima na tajfun Sarika (2016)

Three simulation experiments were conducted on Typhoon (TC) “Sarika” (2016) using the WRF model, different effects of the latent heat in planetary boundary layer and cloud microphysical process on the TC were investigated. The control experiment well simulated the changes in TC track and intensity. The latent heat in planetary boundary layer or cloud microphysics process can affect the TC track and moving speed. Latent heat affects the TC strength by affecting the TC structure. Compared with the CTL experiment, both the NBL experiment and the NMP experiment show weakening in dynamics and thermodynamics characteristics of TC. Without the effect of latent heat, the TC cannot develop upwards and thus weakens in its intensity and reduces in precipitation; this weakening effect appears to be more obvious in the case of closing the latent heat in planetary boundary layer. The latent heat in planetary boundary layer mainly influences the generation and development of TC during the beginning stage, whereas the latent heat in cloud microphysical process is conducive to the strengthen and maintenance of TC in the mature stage. The latent heat energy of the cloud microphysical process in the TC core region is an order of magnitude larger than the surface enthalpy. But the latent heat release of cloud microphysical processes is not the most critical factor for TC enhancement, while the energy transfer of boundary layer processes is more important.Kako bi se ispitali različiti utjecaji latentne topline u planetarnom graničnom sloju i mikrofizičkih procesa u oblacima, WRF modelom su provedena tri eksperimenta za tajfun (TC) “Sarika” (2016). Kontrolnim eksperimentom dobro su simulirane promjene intenziteta i putanja TC-a. Latentna toplina u planetarnom graničnom sloju te mikrofizički procesi u oblacima mogu utjecati na putanju TC i na brzinu njegovog gibanja. Latentna toplina utječe na jačinu TC-a putem promjene strukture TC-a. U usporedbi s CTL eksperimentom i NBL i NMP eksperiment ukazuju na slabljenje dinamike i termodinamičkih svojstava TC-a. Bez utjecaja latentne topline TC se ne može vertikalno razvijati i stoga mu intenzitet slabi, a količina oborine se reducira; to slabljenje je očitije u slučaju kada je latentna toplina ograničena na planetarni granični sloj. Latentna toplina u planetarnom graničnom sloju uglavnom utječe na stvaranje i razvoj TC-a u početnoj fazi, dok latentna toplina vezana za mikrofizičke procese u oblaku pogoduje jačanju i održavanju njegove zrele faze. Latentna toplina mikrofizičkih procesa u oblakcima u jezgri TC-a je za red veličine veća od prizemne entalpije. Međutim, oslobađanje latentne topline pri mikrofizičkim procesima u oblacima nije najvažnije za jačanje TC-a, već je za njegovo jačanje važniji transfer energije u procesima planetarnog graničnog sloja.