Variability-aware request replication for latency curtailment

Processing time variability is commonplace in distributed systems, where resources display disparate performance due to, e.g., different workload levels, background processes, and contention in virtualized environments. However, it is paramount for service providers to keep variability in response time under control in order to offer responsive services. We investigate how request replication can be used to exploit processing time variability to reduce response times, considering not only mean values but also the tail of the response time distribution. We focus on the distributed setup, where replication is achieved by running copies of requests on multiple servers that otherwise evolve independently, and waiting for the first replica to complete service. We construct models that capture the evolution of a system with replicated requests using approximate methods and observe that highly variable service times offer the best opportunities for replication ¿¿¿ reducing the response time tail in particular. Further, the effect of replication is non-uniform over the response time distribution: gains in one metric, e.g., the mean, can be at the cost of another, e.g., the tail percentiles. This is demonstrated in wide range of numerical virtual experiments. It can be seen that capturing service time variability is key to the evaluation of latency tolerance strategies and in their design

Experimental study on strain distribution in externally bonded FRP for shear strengthening of RC beams

2003-2004 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

A standing-wave thermoacoustic engine driven by liquid nitrogen

Thermoacoustic oscillation at cryogenic temperatures, such as Taconis oscillation, has been typically suppressed in the former studies, and few efforts have been made to enhance it. We proposed a standing-wave thermoacoustic engine (TE) driven by liquid cryogens instead of the conventional heat to enhance the thermoacoustic effects and utilize the cold energy. Experimental and theoretical work has been performed on a self-made standingwave TE to demonstrate the feasibility and the operating characteristics of the engine driven by the liquid nitrogen. Experiments show that with nitrogen at 0.5 MPa as a working gas, a pressure ratio of 1.21 is obtained on the TE driven by liquid nitrogen with a much lower temperature difference along the stack compared to that of the conventional TE. The onset temperature difference decreases by 28.9% with helium at 0.63 MPa as a working gas, compared to that of the conventional TE. This study verifies the feasibility of enhancing the thermoacoustic oscillation at cryogenic temperatures. The TEs driven by liquid cryogens such as liquid nitrogen and liquefied nature gas (LNG), may be an alternative for recovering the cold energy

Lithium-Metal Free Sulfur Battery Based on Waste Biomass Anode and Nano-Sized Li2S Cathode

The realization of a stable lithium-metal free (LiMF) sulfur battery based on amorphous carbon anode and lithium sulfide (Li2S) cathode is here reported. In particular, a biomass waste originating full-cell combining a carbonized brewer's spent grain (CBSG) biochar anode with a Li2S-graphene composite cathode (Li2S70Gr30) is proposed. This design is particularly attractive for applying a cost-effective, high performance, environment friendly, and safe anode material, as an alternative to standard graphite and metallic lithium in emerging battery technologies. The anodic and cathodic materials are characterized in terms of structure, morphology and composition through X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron and Raman spectroscopies. Furthermore, an electrochemical characterization comprising galvanostatic cycling, rate capability and cyclic voltammetry tests were carried out both in half-cell and full-cell configurations. The systematic investigation reveals that unlike graphite, the biochar electrode displays good compatibility with the electrolyte typically employed in sulfur batteries. The CBSG/Li2S70Gr30 full-cell demonstrates an initial charge and discharge capacities of 726 and 537 mAh g−1, respectively, at 0.05C with a coulombic efficiency of 74%. Moreover, it discloses a reversible capacity of 330 mAh g−1 (0.1C) after over 300 cycles. Based on these achievements, the CBSG/Li2S70Gr30 battery system can be considered as a promising energy storage solution for electric vehicles (EVs), especially when taking into account its easy scalability to an industrial level. © 2022 The Authors. Energy & Environmental Materials published by John Wiley & Sons Australia, Ltd on behalf of Zhengzhou University

An Adaptive Approach for Processing Evoked Potentials From Human Auditory Cortex

Presents an adaptive approach for the processing of evoked potentials from the an auditory association cortex in humans. The approach can be conceptualized as a bank of least mean square adaptive signal enhancers. The recording data of each trial is then divided into several segments and each segment of data is input to corresponding adaptive signal enhancers. This approach allows the temporal variations of the evoked potential signal to be estimated across individual trials. This is a powerful tool for both clinical and research neurosciences. Two illustrative cases are shown.published_or_final_versio

Field Evaluation of Traditionally Used Plant-Based Insect Repellents and Fumigants Against the Malaria Vector Anopheles darlingi in Riberalta, Bolivian Amazon

Inexpensive insect repellents may be needed to supplement the use of impregnated bed-nets in the Amazon region, where the primary malaria vector, Anopheles darlingi (Root), is exophilic and feeds in the early evening. Three plants that are traditionally used to repel mosquitoes in Riberalta, Bolivian Amazon, were identified by focus group, and then they were tested against An. darlingi as well as Mansonia indubitans (Dyar & Shannon)/Mansonia titillans (Walker). Cymbopogon citratus (Staph), Guatemalan lemongrass, essential oil at 25% was used as a skin repellent, and it provided 74% protection for 2.5 h against predominantly An. darlingi and 95% protection for 2.5 h against Mansonia spp. Attalea princeps (name not verified) husks, burned on charcoal in the traditional way provided 35 and 51% protection against An. darlingi and Mansonia spp., respectively. Kerosene lamps, often used to light rural homes, were used as a heat source to volatilize 100% Mentha arvensis (Malinv ex. Bailey) essential oil, and they reduced biting by 41% inside traditional homes against Mansonia spp., although they were ineffective outdoors against An. darlingi. All three plant-based repellents provided significant protection compared with controls. Plant-based repellents, although less effective than synthetic alternatives, were shown by focus groups to be more culturally acceptable in this setting, in particular para-menthane-3, 8, idol derived from lemon eucalyptus, Corymbia citriodora (Hook). Plant-based repellents have the potential to be produced locally and therefore sold more cheaply than synthetic commercial repellents. Importantly, their low cost may encourage user compliance among indigenous and marginalized populations

The role of diurnal cycle in subduction/obduction

Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Journal of Oceanography 67 (2011): 273-279, doi:10.1007/s10872-011-0025-4.The annual subduction/obduction rate can be calculated in Lagrangian and Eulerian coordinates. In previous studies such calculations were primarily focused on the case with the seasonal cycle only. By extending these calculations to the case including the diurnal cycle of mixed layer depth, the annual subduction/obduction rate can be greatly increased.LLL and FW were supported by National Natural Science Foundation of China under Grant 40906007 and 40890150

The genome and transcriptome of Trichormus sp NMC-1: insights into adaptation to extreme environments on the Qinghai-Tibet Plateau

The Qinghai-Tibet Plateau (QTP) has the highest biodiversity for an extreme environment worldwide, and provides an ideal natural laboratory to study adaptive evolution. In this study, we generated a draft genome sequence of cyanobacteria Trichormus sp. NMC-1 in the QTP and performed whole transcriptome sequencing under low temperature to investigate the genetic mechanism by which T. sp. NMC-1 adapted to the specific environment. Its genome sequence was 5.9 Mb with a G+C content of 39.2% and encompassed a total of 5362 CDS. A phylogenomic tree indicated that this strain belongs to the Trichormus and Anabaena cluster. Genome comparison between T. sp. NMC-1 and six relatives showed that functionally unknown genes occupied a much higher proportion (28.12%) of the T. sp. NMC-1 genome. In addition, functions of specific, significant positively selected, expanded orthogroups, and differentially expressed genes involved in signal transduction, cell wall/membrane biogenesis, secondary metabolite biosynthesis, and energy production and conversion were analyzed to elucidate specific adaptation traits. Further analyses showed that the CheY-like genes, extracellular polysaccharide and mycosporine-like amino acids might play major roles in adaptation to harsh environments. Our findings indicate that sophisticated genetic mechanisms are involved in cyanobacterial adaptation to the extreme environment of the QTP

Automatic Detection and Classification of Breast Tumors in Ultrasonic Images Using Texture and Morphological Features

Due to severe presence of speckle noise, poor image contrast and irregular lesion shape, it is challenging to build a fully automatic detection and classification system for breast ultrasonic images. In this paper, a novel and effective computer-aided method including generation of a region of interest (ROI), segmentation and classification of breast tumor is proposed without any manual intervention. By incorporating local features of texture and position, a ROI is firstly detected using a self-organizing map neural network. Then a modified Normalized Cut approach considering the weighted neighborhood gray values is proposed to partition the ROI into clusters and get the initial boundary. In addition, a regional-fitting active contour model is used to adjust the few inaccurate initial boundaries for the final segmentation. Finally, three textures and five morphologic features are extracted from each breast tumor; whereby a highly efficient Affinity Propagation clustering is used to fulfill the malignancy and benign classification for an existing database without any training process. The proposed system is validated by 132 cases (67 benignancies and 65 malignancies) with its performance compared to traditional methods such as level set segmentation, artificial neural network classifiers, and so forth. Experiment results show that the proposed system, which needs no training procedure or manual interference, performs best in detection and classification of ultrasonic breast tumors, while having the lowest computation complexity