Adaptive just-in-time code diversification

We present a method to regenerate diversified code dynamically in a Java bytecode JIT compiler, and to update the diversification frequently during the execution of the program. This way, we can significantly reduce the time frame in which attackers can let a program leak useful address space information and subsequently use the leaked information in memory exploits. A proof of concept implementation is evaluated, showing that even though code is recompiled frequently, we can achieved smaller overheads than the previous state of the art, which generated diversity only once during the whole execution of a program

The design and implementation of EPL: An event pattern language for active databases

The growing demand for intelligent information systems requires closer coupling of rule-based reasoning engines, such as CLIPS, with advanced data base management systems (DBMS). For instance, several commercial DBMS now support the notion of triggers that monitor events and transactions occurring in the database and fire induced actions, which perform a variety of critical functions, including safeguarding the integrity of data, monitoring access, and recording volatile information needed by administrators, analysts, and expert systems to perform assorted tasks; examples of these tasks include security enforcement, market studies, knowledge discovery, and link analysis. At UCLA, we designed and implemented the event pattern language (EPL) which is capable of detecting and acting upon complex patterns of events which are temporally related to each other. For instance, a plant manager should be notified when a certain pattern of overheating repeats itself over time in a chemical process; likewise, proper notification is required when a suspicious sequence of bank transactions is executed within a certain time limit. The EPL prototype is built in CLIPS to operate on top of Sybase, a commercial relational DBMS, where actions can be triggered by events such as simple database updates, insertions, and deletions. The rule-based syntax of EPL allows the sequences of goals in rules to be interpreted as sequences of temporal events; each goal can correspond to either (1) a simple event, or (2) a (possibly negated) event/condition predicate, or (3) a complex event defined as the disjunction and repetition of other events. Various extensions have been added to CLIPS in order to tailor the interface with Sybase and its open client/server architecture

Safe and automatic live update

Tanenbaum, A.S. [Promotor

COVID-19 and psoriasis: Is it time to limit treatment with immunosuppressants? A call for action

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The swing adsorption reactor cluster for post-combustion CO2 capture from cement plants

The swing adsorption reactor cluster is a promising new method for post-combustion CO2 capture using a synergistic combination of temperature and pressure swings. The pressure swing is carried out by a vacuum pump and allows for 90% CO2 capture using only a small temperature swing, which is carried out by a heat pump. The small temperature swing allows the heat pump to transfer heat from carbonation to regeneration at a very high efficiency, minimizing the energy penalty. When applied to a cement plant, the energy penalty reduces further relative to a coal power plant that has a lower CO2 content in the flue gas. Higher CO2 concentrations allow a given CO2 capture ratio to be achieved with a smaller temperature swing, thus further improving the heat pump efficiency. As a result of the high heat pump efficiency and of the limited amount of waste heat available, heat integration with the cement plant yielded negligible efficiency gains. A swing adsorption reactor cluster post-combustion CO2 capture facility can therefore be constructed independently from the cement plant, making it attractive for retrofits. The specific energy consumption for CO2 avoidance of the process was determined as 2.04 MJLHV/kgCO2 when using electricity from the average European power mix, which is lower than all competing technologies recently assessed in the literature aside from oxyfuel CO2 capture. Primary energy consumption will continue to decline as the electricity sector decarbonizes, increasing the attractiveness of the swing adsorption reactor cluster over coming decades.publishedVersio

Economic assessment of the swing adsorption reactor cluster for CO2 capture from cement production

Cement production is responsible for about 8% of global CO2 emissions. Most of these emissions originate from the process itself and thus cannot be avoided via clean energy, leaving CO2 capture as the only viable solution. This study investigates the prospects of decarbonizing the cement industry via the swing adsorption reactor cluster (SARC) – a new post-combustion CO2 capture technology that requires no integration with the host process, consumes only electrical energy and shows a competitive energy penalty. SARC operates by synergistically combining a temperature swing using a heat pump and a vacuum swing using a vacuum pump. In the present study, the SARC concept is evaluated economically and compared to several benchmarks. SARC achieves CO2 avoidance costs of €52/ton in the base case, which is higher than oxyfuel combustion, similar to calcium looping and lower than four other technology options. SARC can approach the cost of oxyfuel combustion with more optimistic assumptions regarding economies of scale, particularly for the vacuum pump. The local electricity mix is another important factor because SARC, as an electricity consumer, becomes more attractive when the price and CO2 intensity of electricity is low. Furthermore, the simplicity of retrofitting existing cement plants with the SARC process becomes increasingly valuable when rapid CO2 emissions reductions are targeted. SARC is therefore well positioned for a global decarbonization effort aiming to limit global warming well below 2 °C.publishedVersio