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Nano-engineered natural sponge as a recyclable and deformable reactor for ultrafast conversion of pollutants from water
No full textAn alkaline-modified natural sponge was applied as support of gold and silver nanocatalysts and a deformable reactor to hold the reaction solution, quickly adsorb several kinds of environmental pollutants (4-nitrophenol, hexavalent chromium, and methyl orange) and efficiently catalyse their conversion. As the reaction solution is sustained in the connecting micro-pores constructed by the stretched and knotted sponge fibers, the catalytic reaction is free from external mass transfer and suffers slight internal mass transfer limitation. This batch-wise reaction system employing an operation procedure of injection extrusion achieved a nearly complete conversion of the reactants within 1 min or much less. This compressible support can also be packed in a continuous flow reaction system and can be repeated use for 37 times without any loss of catalytic activity. This study provides a generalizable and straightforward strategy for utilizing deformable soft supports that may inspire some unique industrial applications. (c) 2021 Elsevier Ltd. All rights reserved
Keeping our rivers clean: Information-theoretic online anomaly detection for streaming business process events
No full textY Event log anomaly detection aims at identifying anomalous information in the logs generated by the execution of business processes. While several techniques for detecting trace-level anomalies in event logs in offline settings, i.e., when event logs are processed as a batch, have appeared recently in the literature, such techniques are currently lacking for online settings, i.e., when events are processed as a stream. Event log anomaly detection in online settings can be crucial for discovering anomalies in process execution as soon as they occur and, consequently, allowing to take early corrective actions. Moreover, it is also crucial for creating models that can adapt to concept drift in the process generating the events. This paper describes a novel approach to event log anomaly detection in process event streams: we define a general framework in which different anomaly detection methods can be plugged in and we propose and evaluate our own method based on statistical leverage. The leverage is an information-theoretic measure that has been used extensively in statistics to identify outliers and it has been adapted in this paper to the specific scenario of event streams. The proposed approach has been evaluated on artificial and real event streams and also on artificial event streams characterised by concept drift. (C) 2021 Elsevier Ltd. All rights reserved
Jarvis: Large-scale Server Monitoring with Adaptive Near-data Processing
No full textRapid detection of performance and reliability problems is critical to satisfy availability requirements of a datacenter, which typically consists of a large numbers of servers. To address this, we propose Jarvis, a new stream monitoring system that adaptively partitions monitoring queries for execution across data source and stream processor. Jarvis employs two novel schemes to meet the requirements of large-scale server monitoring scenarios. First, Jarvis processes a subset of the input records on each operator through fine-grained data-level partitioning, allowing even resource-intensive operators to execute under resource constraints on each data source and contribute to reducing the amount of data to transmit over the network to the stream processor. Second, Jarvis makes fast and fully decentralized near-data query refinement decisions guided by an approach combining model-based and model-free heuristics, enabling quick adaptation to dynamic resource conditions on each data source. We evaluate the effectiveness of Jarvis on a diverse set of monitoring queries and scales. As compared to the existing schemes, Jarvis handles up to 75% more data source nodes while improving throughput in resource-constrained scenarios by 1.2???4.4??. Moreover, Jarvis achieves these improvements while being able to converge to a stable query partition within a few seconds of a resource change that occurs on data source
Flame edge dynamics in counterflow nonpremixed flames of CH4/He versus air at low strain rates: An experimental and numerical study
No full textThe characteristics of the flame structure, stabilization, and extinction of counterflow nonpremixed flames of CH4/He versus air at low strain rates are investigated by performing a series of experiments and two-dimensional (2-D) numerical simulations. By adopting an experimental methodology using He curtain flow, we can locate the flames near the center of the counterflow burner and measure the critical He mole fraction in the fuel stream, , for flame extinction at very-low strain rates. obtained from 2-D numerical simulations in normal and zero gravity show a good agreement with those from the experiments, which substantiates that the experimental methodology can effectively reduce the buoyancy effect at low strain rates. It is found from various steady and unsteady 2-D numerical simulations that the dynamics of flame edge plays a critical role in determining the flame stabilization and extinction, and the edge flame is stabilized at a location where negative edge flame propagation speed, , balances positive local flow velocity, . The transport budget analysis reveals that despite the negative by the diffusive loss of heat and radicals, the edge flame can survive by the help of the convective gain of heat and radicals from the trailing diffusion flame. It is also found that the counterflow flame can survive the increase of He mole fraction in the fuel stream, , by shrinking its flame length since the local chemical reaction at the flame edge is enhanced with decreasing the flame length. However, as exceeds , a slight inward movement of the edge flame induces a large magnitude of negative compared to positive such that the counterflow flame is totally extinguished by the shrinkage of the outer edge flame toward the flame center
Evolution and Elimination of Reactive Oxygen Species in Lithium-Oxygen Batteries : Singlet Oxygen and Superoxide
No full textDeep Learning Approach for Outage-Constrained Non-Orthogonal Random Access
No full textThis letter presents deep neural network (DNN) approaches for non-orthogonal random access (NORA) systems where several devices are allowed to occupy the identical preamble. We desire to improve the reliability of the packet transmission of NORA devices with a careful management of multi-user interference. A novel transmit power control (TPC) mechanism is proposed which minimizes the maximum transmit power under constraints on link outage probabilities. The nonconvexity and unavailable outage formulations are addressed through DNNs. It is trained to yield feasible TPC solutions for outage constraints based on timing advance values. The viability of the proposed DNN approach is demonstrated with system-level simulations
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Expanded Phase Model for Transformable Design in Defining Its Usage Scenarios for Merits and Demerits
No full textThe product's transformation is considered for its fascination but it is not studied for its usage scenario. This study proposes an expanded phase model that can evaluate the usefulness of transformable products from the perspective of form, function and user scenario of a transformable product. We analyzed purpose of transformation, and identified user benefits from existing transformable products. This model allows designers/team to evaluate usefulness of transformable products by comparing user benefits of the product with appropriateness of form and function in a given usage scenario. ?? The Author(s), 2022
SDRP: Safe, Efficient, and SLO-Aware Workload Consolidation through Secure and Dynamic Resource Partitioning
No full textWorkload consolidation is a widely-used technique to improve the resource utilization of services computing systems by consolidating latency-critical (LC) and batch workloads on the same physical server. The resource manager for workload consolidation dynamically allocates hardware resources (e.g., cores, caches) to the workloads to maximize the resource utilization while satisfying the service-level objective (SLO) of the LC workloads. Since security-critical hardware resources are dynamically allocated across consolidated workloads, information leakages can be created among workloads through microarchitectural side-channel (SC) attacks. Despite extensive prior works, it is yet to investigate efficient system software support for achieving high resource utilization without compromising the SLO and security of consolidated workloads. To bridge this gap, we propose SDRP, secure and dynamic resource partitioning for safe, efficient, and SLO-aware workload consolidation. As with the state-of-the-art techniques, SDRP dynamically allocates hardware resources to enhance the resource utilization and provide the SLO guarantees. In contrast to the state-of-the-art techniques, SDRP dynamically sanitizes security-critical hardware resources to robustly defeat microarchitectural SC attacks. Our quantitative evaluation demonstrates that SDRP achieves high resource sanitization quality, introduces low performance overheads, delivers high resource utilization with the SLO and security guarantees, and defeats the last-level cache (LLC)-based SC attack
Carbon-based catalyst for environmental bioremediation and sustainability: Updates and perspectives on techno-economics and life cycle assessment
No full textGlobal rise in the generation of waste has caused an enormous environmental concern and waste management problem. The untreated carbon rich waste serves as a breeding ground for pathogens and thus strategies for production of carbon rich biochar from waste by employing different thermochemical routes namely hydrothermal carbonization, hydrothermal liquefaction and pyrolysis has been of interest by researchers globally. Biochar has been globally produced due to its diverse applications from environmental bioremediation to energy storage. Also, several factors affect the production of biochar including feedstock/biomass type, moisture content, heating rate, and temperature. Recently the application of biochar has increased tremendously owing to the cost effectiveness and eco-friendly nature. Thus this communication summarized and highlights the preferred feedstock for optimized biochar yield along with the factor influencing the production. This review provides a close view on biochar activation approaches and synthesis techniques. The application of biochar in environmental remediation, composting, as a catalyst, and in energy storage has been reviewed. These informative findings were supported with an overview of lifecycle and techno-economical assessments in the production of these carbon based catalysts. Integrated closed loop approaches towards biochar generation with lesser/zero landfill waste for safeguarding the environment has also been discussed. Lastly the research gaps were identified and the future perspectives have been elucidated