2,354 research outputs found
Non-Abelian (Hyperscaling Violating) Lifshitz Black Holes in General Dimensions
We consider Einstein gravities coupled to a cosmological constant and
multiple Yang-Mills fields in general dimensions and find that the
theories admit colored Lifshitz solutions with dynamic exponents . We also
introduce a Maxwell field and construct exact electric charged black holes that
asymptote to the colored Lifshitz spacetimes and analyse their
thermodynamical first law. Furthermore, we introduce a dilaton to the system
and construct Lifshitz spacetimes with hyperscaling violations. After turning
on the Maxwell field, we obtain a class of hyperscaling violating Lifshitz
black holes when .Comment: Latex, 12 pages, a published version in PL
Reliability and security in low power circuits and systems
With the massive deployment of mobile devices in sensitive areas such as healthcare and defense, hardware reliability and security have become hot research topics in recent years. These topics, although different in definition, are usually correlated. This dissertation offers an in-depth treatment on enhancing the reliability and security of low power circuits and systems. The first part of the dissertation deals with the reliability of sub-threshold designs, which use supply voltage lower than the threshold voltage (Vth) of transistors to reduce power. The exponential relationship between delay and Vth significantly jeopardizes their reliability due to process variation induced timing violations. In order to address this problem, this dissertation proposes a novel selective body biasing scheme. In the first work, the selective body biasing problem is formulated as a linearly constrained statistical optimization model, and the adaptive filtering concept is borrowed from the signal processing community to develop an efficient solution. However, since the adaptive filtering algorithm lacks theoretical justification and guaranteed convergence rate, in the second work, a new approach based on semi-infinite programming with incremental hypercubic sampling is proposed, which demonstrates better solution quality with shorter runtime. The second work deals with the security of low power crypto-processors, equipped with Random Dynamic Voltage Scaling (RDVS), in the presence of Correlation Power Analysis (CPA) attacks. This dissertation firstly demonstrates that the resistance of RDVS to CPA can be undermined by lowering power supply voltage. Then, an alarm circuit is proposed to resist this attack. However, the alarm circuit will lead to potential denial-of-service due to noise-triggered false alarms. A non-zero sum game model is then formulated and the Nash Equilibria is analyzed --Abstract, page iii
Book Review: Dire Straits-Education Reforms: Ideology, Vested Interests and Evidence by Montserrat Gomendio and José Ignacio Wert
Education, as a practical activity to improve the comprehensive quality of human beings, not only plays a role in the transmission and inheritance of culture but also has intimate ties to the growth of life and development of economy and society. In this book, the authors Montserrat Gomendio and José Ignacio Wert discuss the reasons why education reforms are difficult to implement but easy to reverse, taking into account the valuable evidence they have obtained in designing and implementing education reforms in Spain and their subsequent experience at the OECD (Organization for Economic Cooperation and Development) advising governments worldwide. This dialogue on education is like a breath of fresh air for the reader. By comparing education policies from an international perspective and analyzing the interplay between education reforms, ideology and vested interests, the authors provide insights into the positive and negative factors that influence education reforms. The book consists of seven chapters
Qubit Reset with a Shortcut-to-Isothermal Scheme
Landauer's principle shows that the minimum energy cost to reset a classical
bit in a bath with temperature is in the infinite time.
However, the task to reset the bit in finite time has posted a new challenge,
especially for quantum bit (qubit) where both the operation time and
controllability are limited. We design a shortcut-to-isothermal scheme to reset
a qubit in finite time with limited controllability. The energy cost is
minimized with the optimal control scheme with and without nonholonomic
constraint. This optimal control scheme can provide a reference to realize
qubit reset with minimum energy cost for the limited time.Comment: 8 pages, 7 figure
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