Technical University of Berlin

About: Technical University of Berlin is a education organization based out in Berlin, Germany. It is known for research contribution in the topics: Quantum dot & Laser. The organization has 27292 authors who have published 59342 publications receiving 1414623 citations. The organization is also known as: Technische Universität Berlin & TU Berlin.

Method and system for the transparent migration of virtual machines storage

Abstract: Method for transferring storage data of a virtual machine to be migrated from a first host device to a second host device via a communication network, including: running the virtual machine on the first host device; storing, on a local storage device of the first host device, a disk image used by the virtual machine; detecting, while the virtual machine is running on the first host device, any changes made to the disk image used by the virtual machine; establishing a connection over the communication network from the first host device to the second host device; transferring, to the second host device while the virtual machine is running on the first host device, the disk image used by the virtual machine and the detected any changes made; modifying the disk image transferred to the second host device in response to the detected any changes transferred to the second host device; and starting, using the modified disk image, a migrated virtual machine on the second host device at a current state of the virtual machine running on the first host device.

A comparative perspective of electrochemical and photochemical approaches for catalytic H2O2 production

Abstract: Hydrogen peroxide (H2O2) has a wide range of important applications in various fields including chemical industry, environmental remediation, and sustainable energy conversion/storage. Nevertheless, the stark disconnect between today's huge market demand and the historical unsustainability of the currently-used industrial anthraquinone-based production process is promoting extensive research on the development of efficient, energy-saving and sustainable methods for H2O2 production. Among several sustainable strategies, H2O2 production via electrochemical and photochemical routes has shown particular appeal, because only water, O2, and solar energy/electricity are involved during the whole process. In the past few years, considerable efforts have been devoted to the development of advanced electrocatalysts and photocatalysts for efficient and scalable H2O2 production with high efficiency and stability. In this review, we compare and contrast the two distinct yet inherently closely linked catalytic processes, before we detail recent advances in the design, preparation, and applications of different H2O2 catalyst systems from the viewpoint of electrochemical and photochemical approaches. We close with a balanced perspective on remaining future scientific and technical challenges and opportunities.

Cujo: efficient detection and prevention of drive-by-download attacks

Abstract: The JavaScript language is a core component of active and dynamic web content in the Internet today. Besides its great success in enhancing web applications, however, JavaScript provides the basis for so-called drive-by downloads---attacks exploiting vulnerabilities in web browsers and their extensions for unnoticeably downloading malicious software. Due to the diversity and frequent use of obfuscation in these attacks, static code analysis is largely ineffective in practice. While dynamic analysis and honeypots provide means to identify drive-by-download attacks, current approaches induce a significant overhead which renders immediate prevention of attacks intractable.In this paper, we present Cujo, a system for automatic detection and prevention of drive-by-download attacks. Embedded in a web proxy, Cujo transparently inspects web pages and blocks delivery of malicious JavaScript code. Static and dynamic code features are extracted on-the-fly and analysed for malicious patterns using efficient techniques of machine learning. We demonstrate the efficacy of Cujo in different experiments, where it detects 94% of the drive-by downloads with few false alarms and a median run-time of 500 ms per web page---a quality that, to the best of our knowledge, has not been attained in previous work on detection of drive-by-download attacks.

On the relation between the open‐circuit voltage and quasi‐Fermi level splitting in efficient perovskite solar cells

Abstract: Today's perovskite solar cells (PSCs) are limited mainly by their open‐circuit voltage (VOC) due to nonradiative recombination. Therefore, a comprehensive understanding of the relevant recombination pathways is needed. Here, intensity‐dependent measurements of the quasi‐Fermi level splitting (QFLS) and of the VOC on the very same devices, including pin‐type PSCs with efficiencies above 20%, are performed. It is found that the QFLS in the perovskite lies significantly below its radiative limit for all intensities but also that the VOC is generally lower than the QFLS, violating one main assumption of the Shockley‐Queisser theory. This has far‐reaching implications for the applicability of some well‐established techniques, which use the VOC as a measure of the carrier densities in the absorber. By performing drift‐diffusion simulations, the intensity dependence of the QFLS, the QFLS‐VOC offset and the ideality factor are consistently explained by trap‐assisted recombination and energetic misalignment at the interfaces. Additionally, it is found that the saturation of the VOC at high intensities is caused by insufficient contact selectivity while heating effects are of minor importance. It is concluded that the analysis of the VOC does not provide reliable conclusions of the recombination pathways and that the knowledge of the QFLS‐VOC relation is of great importance.