Small Degradation Research Articles

Durability performance of self-compacting concrete produced using CO2 as an admixture

This research investigates the fresh characteristics and durability of self-compacting concrete (SCC) made using CO2 as an admixture. In the existing practice, CO2 is added to concrete mainly through accelerated carbonation curing. That has many limitations, such as low diffusion rate, requirements of the large airtight chamber, and use in precast concrete only. To overcome these limitations, the current study employed a CO2 mineralization approach. As cementitious materials hydrate during mixing, CO2 reacts with it and produces more hydration products. In addition, calcium carbonate particles are formed in situ, filling the minute pores and densifying the SCC matrix. The present research results reveal that a small quantity of CO2 mineralization improves the SCC compressive strength and durability; the best durability is achieved at 0.3% mineralization of CO2 by the weight of the cement used. Compare to normal SCC, a 4.3% higher compressive strength of CO2 mineralized SCC was noticed at 28 days of testing. 0.05 % lowers weight gain and 1.88 % higher compressive strength was noticed in CO2 mineralized SCC at 180 days of 5% sodium sulfate exposure condition. Similarly, the rapid chloride penetration test result shows that 11.35% lesser chloride ions pass from CO2 mineralized SCC compared to normal SCC. The fresh characteristics of the SCC as a result of CO2 mineralization behave similarly to reference SCC with small degradation that is considered acceptable. Hence, thepresent study demonstrates that CO2 can be used beneficially in concrete to enhance its properties and lower CO2 emissions into the atmosphere.

Microwave-Assisted Metal-Organic Frameworks Derived Synthesis of Zn2GeO4 Nanowire Bundles for Lithium-Ion Batteries.

Germanium-based multi-metallic-oxide materials have advantages of low activation energy, tunable output voltage, and high theoretical capacity. However, they also exhibit unsatisfactory electronic conductivity, sluggish cation kinetics, and severe volume change, resulting in inferior long-cycle stability and rate performance in lithium-ion batteries (LIBs). To solve these problems, we synthesize metal-organic frameworks derived from rice-like Zn2GeO4 nanowire bundles as the anode of LIBs via a microwave-assisted hydrothermal method, minimizing the particle size and enlarging the cation's transmission channels, as well as, enhancing the electronic conductivity of the materials. The obtained Zn2GeO4 anode exhibits superior electrochemical performance. A high initial charge capacity of 730 mAhg-1 is obtained and maintained at 661 mAhg-1 after 500 cycles at 100 mA g-1 with a small capacity degradation ratio of ~0.02% for each cycle. Moreover, Zn2GeO4 exhibits a good rate performance, delivering a high capacity of 503 mA h g-1 at 5000 mA g-1. The good electrochemical performance of the rice-like Zn2GeO4 electrode can be attributed to its unique wire-bundle structure, the buffering effect of the bimetallic reaction at different potentials, good electrical conductivity, and fast kinetic rate.

Evaluation of the interaction between SiC, pre-oxidized FeCrAlMo with aluminized and pre-oxidized Fe-8Cr-2W in flowing PbLi

Dissimilar materials interactions are a major concern when liquid metals are used as a working fluid. To simulate a dual-coolant PbLi blanket, chemical vapor deposited (CVD) SiC, pre-oxidized FeCrAlMo (APMT) and pre-oxidized aluminized coating on Fe-8Cr-2 W (F82H) specimens were exposed to flowing commercial Pb-17at.%Li with a peak temperature of 650 °C in a pre-oxidized APMT thermal convection loop (TCL) for 1000 h. Similar to prior results in static PbLi, the coated F82H showed small mass changes and limited degradation of room-temperature tensile properties. After exposure, the α-Al2O3 on the surface coated F82H reacted with the PbLi to form LiAlO2. However, no significant Al coating loss or interdiffusion was observed. Mass transfer was observed between the APMT, TCL and the SiC specimens. Fe, Cr and Ni were dissolved into the molten flowing PbLi and transported through the TCL to react with the SiC specimens. Compared to a prior experiment with a majority of bare FeCrAl specimens that were exposed in a TCL with a peak temperature of 700 °C for 1000 h, the SiC reaction was reduced to only a few microns of carbides and silicides. Oxygen dissolved in the molten PbLi sustained the formation of an Al2O3 scale on the surface of the coating and induced the formation of a thin surface SiO2 layer on the surface of the SiC.

Dual-band and dual-polarized reflective Fresnel zone plate design based on Fractal shape

In this study, a dual-polarized and dual band reflective Fresnel zone plate with reconfigurable beam is proposed on the basis of fractal frequency selective surface (FSS) unit with nearly 360° phase tunability. Firstly, a new phase distribution calculation strategy based on Fresnel diffraction theory is proposed to improve the performance under certain scenarios like sparse arrays. Then, a novel fractal shape is put forward and applied to the design of the Fresnel zone plate. The introduction of the fractal structure makes the unit cell perform dual band, dual polarization and 309° phase tunability characteristics. Due to the self-symmetry of the unit cell, the proposed fractal Fresnel zone plate (FFZP) is capable of beam steering in ± 45° in both TE and TM incident waves. Besides, the proposed structure shows small performance degradation when it comes to oblique incidence up to 45°, which decreases the focal diameter ratio and profile of the proposed FFZP. The operating bandwidth of the FFZP can reach up to 700 MHz at X and Ku bands. It is applicable in a wide range of RF and microwave settings such as satellite and base station.

Abstract 481: Investigating molecular glues as a new therapeutic approach to high-risk neuroblastoma

Abstract High-risk neuroblastoma (NB) is the most common extracranial solid tumor of childhood. Despite extensive study, treatments remain highly toxic and are often insufficient to cure. Thus, there is an urgent need to develop more effective and less toxic treatments for children with NB. NB commonly displays reliance on a relatively small cohort of transcription factors (TFs) and epigenetic proteins to drive cell growth, however, many of these targets are inaccessible with conventional small molecules. In recent years, new modalities such as targeted protein degradation (TPD) have emerged. TPD may permit small molecule degradation of traditionally “undruggable” targets, such as TFs. This makes TPD a particularly attractive modality for defining new therapeutic strategies for high-risk NB. One category of TPD agents are molecular glues (MGs). MGs are monovalent small molecules capable of simultaneously binding to an E3 ligase receptor such as CRBN (cereblon), and a target protein of interest. Importantly, in comparison to conventional protein inhibitors, MGs do not require a conventional binding pocket on the protein of interest to bind to it, and can be utilized in sub-stoichiometric concentrations. Thus, this may result in the recruitment, polyubiquitination, and subsequent proteasomal degradation of proteins previously thought to be “undruggable.” Here, we demonstrate that high-risk NB cells are critically sensitive to a cluster of previously unknown MGs. We performed high-throughput screening of a proprietary library (>4000 unique compounds) of MGs in two MYCN-amplified NB cell lines, Kelly and MHHNB11. These two cell lines demonstrate a strikingly close correlation in Cell-Titer Glo-based growth response to MGs, as compared with an outgroup of other MG-responsive cancer cell lines. We identified a unique subcluster of 112 common MGs that display >70% growth inhibition in both cell lines. To identify the mechanism of cell growth inhibition, we established Kelly cells with stable knockout of CRBN, and coupled these with screening to confirm that the majority of these MGs (84%; 94/112) require CRBN expression. To rule out common off-target effects of MGs, candidate compounds were then tested in cells transgenically expressing either wild-type or degradation-resistant GSPT1 (G575N) constructs, revealing a subset of MGs retaining cytotoxicity without effecting GSPT1 protein levels. Current studies are focused on determining the targets of these high confidence MGs, as a foundation for preclinical in vivo studies. These studies will identify new compounds with defined mechanisms of action, with an ultimate goal of developing new treatments that are more effective and less toxic for children with NB. Citation Format: Ian Delahunty, Gisele Nishiguchi, Yang Zhang, Abigail Fish, Anand Mayasundari, Jun Qi, Brian Abraham, Anang Shelat, Zoran Rankovic, Adam Durbin. Investigating molecular glues as a new therapeutic approach to high-risk neuroblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 481.

Proposed approximate hybrid memory architecture for handheld multimedia devices

Nowadays Handheld multimedia devices demand is growing rapidly, as the demand for mobility in work and lifestyle increases. Power consumption has become the paramount concern in the design of Handheld multimedia battery-operated devices. Approximate computing promises energy efficiency computing paradigms when small quality degradation is permissible. Most multimedia processing is image or video processing, where the end user is a human. The imperceptibility of the human visual system is to allow the output of this processing to be approximate rather than accurate. This research paper proposed an energy-efficient Moving Picture Experts Group 4 (MPEG-4) video decoder architecture with a circuit-level approximate method for Handhandle multimedia devices. Hence, in this research work instead of using conventional 6T memory cells during video decoding processing, an approximate Hybrid 6T/8T memory architecture is proposed, where the 8-bit Luminance pixels are stored favourably in consonance with their effect on the output quality. The higher order luminance bits (MSBs) require high stability and thus these bits are stored in the 8T bit cells and the remaining bits (LSBs) are stored in the conventional 6T bit cells for more optimal configurations compared with previous work. The failure probability of 6T cells is significantly large 0.0988 at 600 mV supply voltage (as compared to 0.28*10^-2 at 800 mV supply voltage), leading to a decrease in the output quality of the decoded video. The hybrid memory matrix formulation calculates that storing higher-order MSB bits in highly stable memory cells will provide high-quality video processing compared to the conventional technique because the human eye is more susceptible to higher-order luminance bits. The proposed approximate 6T/8T hybrid memory units, and evaluate them to demonstrate the efficacy of our approach. Simulations result indicate power savings of up to 50% with an insignificant loss in output quality (3.6 dB) when compared to the conventional memory unit. Compared to the hybrid and conventional 6T memory array at 600 mV supply voltage, the worst minimum PSNR is 15.04 dB improved.

MOVPE studies of zincblende GaN on 3C-SiC/Si(0 0 1)

Cubic zincblende GaN films were grown by metalorganic vapour-phase epitaxy on 3C-SiC/Si (001) templates and characterized using Nomarski optical microscopy, atomic force microscopy, X-ray diffraction, and transmission-electron microscopy. In particular, structural properties were investigated of films where the growth temperature of a GaN epilayer varied in the range of 830 °C to 910 °C and the gas-phase V/III-ratio varied from 15 to 1200 at a constant reactor pressure of 300 Torr. It was observed that with increasing epi temperature at a constant V/III-ratio of 76, the film surface consisted of micrometer-sized elongated features aligned along [1–10] up to a temperature of 880 °C. The zincblende phase purity of such samples was generally high with a wurtzite fraction of less than 1%. When grown above 880 °C the GaN surface morphology degraded and the zincblende phase purity reduced as a result of inclusions with the wurtzite phase. A progressive narrowing of the 002 reflection with increasing epi growth temperature suggested an improvement of the film mosaicity. With increasing V/III-ratio at a constant growth temperature of 880 °C, the film surface formed elongated features aligned along [1–10] at V/III values between 38 and 300 but the morphology became granular at both lower and higher V/III values. The zincblende phase purity is high at V/III values below 300. A slight broadening of the 002 X-ray diffraction reflection with increasing V/III-ratio indicated a small degradation of mosaicity. Scanning electron diffraction analyses of cross-sectional transmission-electron micrographs taken of a selection of samples illustrated the spatial distribution, quantity and structure of wurtzite inclusions within the zincblende GaN matrix. Within the limits of this study, the optimum epilayer growth conditions at a constant pressure of 300 Torr were identified to be at a temperature around 860 °C to 880 °C and a V/III-ratio in the range of 23 to 76, resulting in relatively smooth, zincblende GaN films without significant wurtzite contamination.

Tunable Heterogeneous FeCo Alloy-Mo0.82N Bifunctional Electrocatalysts for Temperature-Adapted Zn–Air Batteries

The practical applications of temperature-tolerant Zn-air batteries (ZABs) rely on highly active and stable bifunctional catalysts that accelerate cathodic oxygen reduction (ORR) and oxygen evolution (OER) reactions. Herein, we successfully integrated fascinating transition metal nitrides and FeCo alloys through a simple coordination assembly and pyrolysis process. Importantly, the alloy-to-nitride ratio in the heterogeneous catalyst can be carefully regulated through the subsequent etching process. Moreover, the composition-dependent ORR/OER performance of the FeCo-Mo0.82N catalysts was revealed. Aqueous ZABs using the optimized FeCo-Mo0.82N-60 as a cathode exhibit a high peak power density of 149.7 mW cm-2 and an impressive stability of 600 h with a low charge-discharge voltage gap decay rate of 0.025 mV h-1, which exceeds those of most of recent reports. Furthermore, the FeCo-Mo0.82N-60-based flexible ZABs display a small specific capacity degradation (3%) from 40 to -10 °C, demonstrating excellent temperature tolerance.

Identification of regulatory pathways of miRna and phasiRna related to flax lignan synthesis

ABSTRACT Lignan is an important functional health care substance. At present, research on the molecular mechanism of flax lignan biosynthesis is primarily focused at the transcriptional level, with no research on the regulatory mechanism of small RNAs, particularly phased small interfering RNAs (phasiRNAs) related to lignan content. In this study, we used flax seeds at different developmental stages as materials to construct small RNA libraries and degradation libraries. Eighteen known and 4 new miRNA families containing 40 and 4 miRNA members, respectively, were identified. A total of 104 target genes were identified. Using small RNA data for a genome-wide search, a total of twenty-two 21-nt PHAS loci and twenty-eight 24-nt PHAS loci were obtained. Five miRNAs capable of triggering target genes to produce phasiRNAs were identified. These 5 miRNAs triggered their target genes to produce 39 phasiRNAs. Three complete miRNA-PHAS loci-phasiRNA-target gene functional regulatory pathways were identified. Furthermore, qRT‒PCR confirmed an obvious regulatory relationship among the regulatory pathways. In this study, the molecular regulatory network among flax miRNAs, phasiRNAs and target genes was described from the perspective of lignan synthesis, providing an important scientific basis for the study of flax molecular breeding for high lignan content.

Kinetic Modeling of the Anodic Degradation of Ni-EDTA Complexes: Insights into the Reaction Mechanism and Products

In this study, an electrochemical advanced oxidation process (EAOP) was employed to effectively degrade complexes of nickel and ethylenediaminetetraacetic acid (EDTA) present in electroless nickel plating wastewaters. Our results show that Ni-EDTA complexes can be effectively degraded by an EAOP with degradation of the complexes occurring at/near the anode surface via interaction with hydroxyl radicals generated on water splitting. Our results further show that the rate of Ni-EDTA degradation is not a function of the rate of any particular chemical reaction but, rather, is controlled by the rate of transport of Ni-EDTA to the anode surface. The oxidation of EDTA to smaller noncomplexing entities releases Ni2+, which is subsequently deposited onto the cathode as Ni0. While complete Ni-EDTA removal and Ni recovery are achieved within 2 h, the overall TOC removal by EAOP is limited, with only 50% TOC removal achieved after 2 h of treatment. The low affinity of small molecular weight EDTA degradation products (such as formic acid, glycine, oxamic acid, and acetic acid) for the anode surface limits oxidation of these compounds and overall TOC removal by the anodic oxidation process. We have developed a mathematical kinetic model that satisfactorily describes Ni-EDTA removal, Ni recovery, and TOC removal over a range of Ni and EDTA concentrations and provides a good description of the oxidation of various EDTA degradation intermediates. The mathematical model developed here, when coupled with the hydrodynamics of the electrochemical cell using a computational fluid dynamics tool, can assist in both cell design and the selection of operating parameters such that the performance of the EAOP process for Ni-EDTA degradation and TOC removal is optimized.

Binarizing Split Learning for Data Privacy Enhancement and Computation Reduction

Split learning (SL) enables data privacy preservation by allowing clients to collaboratively train a deep learning model with the server without sharing raw data. However, SL still has limitations such as potential data privacy leakage and high computation for clients. In this paper, we propose to binarize the SL local layers for faster computation (up to 17.5 times less forward-propagation time in both training and inference phases on mobile devices) and reduced memory usage (up to 32 times less memory and bandwidth requirements). More importantly, the binarized SL (B-SL) model can reduce privacy leakage from SL smashed data with merely a small degradation in model accuracy. To further enhance privacy preservation, we also propose two novel approaches: 1) training with additional local leak loss and 2) applying differential privacy, which could be integrated separately or concurrently into the B-SL model. Experimental results with different datasets have affirmed the benefits of the B-SL models compared with several benchmark models. The effectiveness of B-SL models against feature-space hijacking attack (FSHA) is also illustrated. Our results have demonstrated B-SL models are promising for lightweight IoT/mobile applications with high privacy-preservation requirements such as mobile healthcare applications.

Preparation and characterization of nanostructured Fe-doped CoTe2 electrocatalysts for the oxygen evolution reaction.

The key step for hydrogen production through water electrolysis is the development of highly efficient and inexpensive oxygen evolution reaction (OER) catalysts. In this work, we report the successful synthesis of a nanostructured Fe-doped cobalt-based telluride (Fe-doped CoTe2) catalyst on Co foam by a simple one-step hydrothermal synthesis method, which shows excellent OER performance. The influences of Fe doping amounts and reaction temperatures on the morphology, structure, composition, and the OER performance of cobalt-based tellurides have been systematically studied. The optimal sample Co@0.3 g FeCoTe2-200 exhibits a low overpotential of 300 mV at a current density of 10 mA cm-2, and a small Tafel slope of 36.99 mV dec-1, outperforming the undoped cobalt telluride catalysts (Co@CoTe2-200). The Co@0.3 g FeCoTe2-200 electrode also reveals a small overpotential degradation of around 26 mV after an 18-hour continuous OER process. These results unambiguously confirm that Fe doping helps improve the OER activity and long-term catalytic stability. The superior performance of nanostructured Fe-doped CoTe2 can be attributed to the porous structure and the synergistic effect of Co and Fe elements. This study provides a new approach for the preparation of bimetallic telluride catalysts with enhanced OER performance, and Fe-doped CoTe2 holds substantial promise for use as a high-efficiency, cost-effective catalyst for alkaline water electrolysis.

Robust Long-Term Hand Grasp Recognition With Raw Electromyographic Signals Using Multidimensional Uncertainty-Aware Models.

Hand grasp recognition with surface electromyography (sEMG) has been used as a possible natural strategy to control hand prosthetics. However, effectively performing activities of daily living for users relies significantly on the long-term robustness of such recognition, which is still a challenging task due to confused classes and several other variabilities. We hypothesise that this challenge can be addressed by introducing uncertainty-aware models because the rejection of uncertain movements has previously been demonstrated to improve the reliability of sEMG-based hand gesture recognition. With a particular focus on a very challenging benchmark dataset (NinaPro Database 6), we propose a novel end-to-end uncertainty-aware model, an evidential convolutional neural network (ECNN), which can generate multidimensional uncertainties, including vacuity and dissonance, for robust long-term hand grasp recognition. To avoid heuristically determining the optimal rejection threshold, we examine the performance of misclassification detection in the validation set. Extensive comparisons of accuracy under the non-rejection and rejection scheme are conducted when classifying 8 hand grasps (including rest) over 8 subjects across proposed models. The proposed ECNN is shown to improve recognition performance, achieving an accuracy of 51.44% without the rejection option and 83.51% under the rejection scheme with multidimensional uncertainties, significantly improving the current state-of-the-art (SoA) by 3.71% and 13.88%, respectively. Furthermore, its overall rejection-capable recognition accuracy remains stable with only a small accuracy degradation after the last data acquisition over 3 days. These results show the potential design of a reliable classifier that yields accurate and robust recognition performance.

Degradation of bisphenol A in an oxidation system constructed from Mo2C MXene and peroxymonosulfate

The etched Mo2C MXene with a layered structure was characterized as an environmentally friendly catalyst in the bisphenol A (BPA) removal by advanced oxidation. 99.75% of BPA was degraded in the oxidation system constructed using Mo2C MXene and peroxymonosulfate (PMS). The Mo2C MXene was recyclable, with a high removal percentage (89.29%) of BPA after even four cycles. The catalysis of Mo2C MXene on PMS was due to the Mo-deficit vacancy defects. The electron paramagnetic resonance technique and density functional theory (DFT)-based density of states calculations verified defect signals. In addition, the defective Mo2C MXene and PMS have strong binding and electron transfer capabilities. The reactive oxygen species (ROS, including O2•−, 1O2, SO4•−, and •OH) produced by Mo2C MXene activates PMS, leading to BPA degradation. The condensed Fukui function predicted the active sites of the BPA molecule and found that the O1, O2, C3, C4, C6, C12, C15, and C16 sites have higher electrophilic reactivity. The C, C–C bonds, or C4/C16 sites in the isopropyl group connecting the two phenolic rings were attacked first, then further transformed BPA into non-toxic or low toxic small molecule degradation products through a series of reactions such as bond-breaking, addition, hydroxylation, and ring-opening. Moreover, the Mo2C MXene/PMS system has strong applicability in actual water bodies. The study provides valuable insights into PMS activation by two-dimensional MXenes to remove toxic organic pollutants in an aqueous matrix.

HunterPlus: AI based energy-efficient task scheduling for cloud–fog computing environments

Cloud computing is a mainstay of modern technology, offering cost-effective and scalable solutions to a variety of different problems. The massive shift of organization resource needs from local systems to cloud-based systems has greatly increased the costs incurred by cloud providers in expanding, maintaining, and supplying server, storage, network, and processing hardware. Due to the large scale at which cloud providers operate, even small performance degradation issues can cause energy or resource usage costs to rise dramatically. One way in which cloud providers may improve cost reduction is by reducing energy consumption. The use of intelligent task-scheduling algorithms to allocate user-deployed jobs to servers can reduce the amount of energy consumed. Conventional task scheduling algorithms involve both heuristic and metaheuristic methods. Recently, the application of Artificial Intelligence (AI) to optimize task scheduling has seen significant progress, including the Gated Graph Convolution Network (GGCN). This paper proposes a new approach called HunterPlus which examine the effect of extending the GGCN’s Gated Recurrent Unit to a Bidirectional Gated Recurrent Unit. The paper also studies the utilization of Convolutional Neural Networks (CNNs) in optimizing cloud–fog task scheduling. Experimental results show that the CNN scheduler outperforms the GGCN-based models in both energy consumption per task and job completion rate metrics by at least 17 and 10.4 percent, respectively.

Spin-Trapping Analysis of the Thermal Degradation Reaction of Polyamide 66.

The radical mechanisms of the thermal degradation of polyamide 66 (PA66) occurring under a vacuum at a temperature range between 80 °C and 240 °C (which includes the temperature of practical applications) were investigated using a spin-trapping electron spin resonance (ST-ESR) technique, as well as FTIR, TG-DTA, and GPC methods. No significant weight loss and no sign of thermal degradation are observed at this temperature range under oxygen-free conditions, but a slight production of secondary amine groups is confirmed by FTIR. GPC analysis shows a small degradation by the main chain scission. ST-ESR analysis reveals two intermediate radicals which are produced in the thermal degradation of PA66: (a) a ●CH2- radical generated by main chain scission and (b) a -●CH- radical generated by hydrogen abstraction from the methylene group of the main chain. The ST-ESR result does not directly confirm that a -NH-●CH- radical is produced, although this reaction has been previously inferred as the initiation reaction of the thermal degradation of PA; however, the presence of -●CH- radicals strongly suggests the occurrence of this initiation reaction, which takes place on the α-carbon next to the NH group. The ST-ESR analysis reveals very small levels of reaction, which cannot be observed by common analytical methods such as FTIR and NMR.

Analysis on the transverse compression performance of the CORC cable

The conductor on round core (CORC) cable is considered as one of the best candidate cables for next generation fusion project due to its advantages of high current density, small cabling degradation and excellent magnetic field performance. Nevertheless, the CORC cable will be affected by huge transverse compression force during production and transportation, especially during operation in fusion project, which is the main reason that the current-carrying capacity of CORC cable will be irreversible degradation. There is little research on the transverse compression performance of CORC cables at present, and the influence rules of some cable parameters on its transverse compression performance are not yet clear. Therefore, in this paper, transverse compression tests are carried out on CORC cables of different former sizes, materials, and structures. The experimental results show that the larger the cable former size, the better its transverse compression performance. The transverse compression load limit of hollow tube former cable is larger than that of solid bar former cable. The performance of stainless steel bar former cable is similar to that of copper bar former cable. The limit value of transverse compression load of copper hollow tube former cable is larger than that of stainless steel hollow tube former cable. A 3D finite element model is also established to explain the internal reasons for the differences of current-carrying capacity decrease tendency of different CORC cables. The research results can provide theoretical basis for the selection of former of CORC cable in the future. In addition, the influence of load block structure on the CORC cable’s transverse compression load limit is also studied in this paper. The results show that the arc block can significantly increase the transverse compression load limit of CORC cable. The research results can provide a basis for the selection of the structure of support former when making cable in conduit conductor and the structure of coil former when winding CORC coil magnet.

Implementation of real contact behaviour in the DEM modelling of triaxial tests on railway ballast

In the Discrete Element modelling of soils, the micromechanical behaviour at contacts has often been considered to have a minor influence on the macromechanical response, leaving basic theoretical models (e.g., Hertz) to describe the contact response in the normal direction. A realistic description of the contact response may be crucial especially when investigating small strain ranges. Recent experimental inter-particle loading tests on gravel suggest that the classic contact models fail to reproduce certain mechanical features, especially when roughness is significant. Here, some of these experimental observations, including a softer response than the Hertz model under loading in the normal direction, and plasticity on unloading, are implemented in a DEM model for the simulation of small strain tests on railway ballast. The influence of these features on small strain stiffness is highlighted. A micromechanical analysis is carried out to show how each of the contact-level features introduced affects the macroscopic response. • Classic contact models do not work well for rough surfaces. • Accounting for lower normal stiffness due to contact with asperities and plasticity. • True contact behaviour implemented in numerical DEM simulations of ballast. • Contact behaviour can explain small strain stiffness degradation.

PAPR Reduction Techniques and Their BIT Error Rate Measurement at OFDM in LTE System

Orthogonal frequency division multiplexing (OFDM) has become an indispensable part of waveform generation in wideband digital communication since its first appearance in digital audio broadcasting (DAB)and it is indeed in use. These descriptions are simplified version of the detailed descriptions provided by 3gpp. It is a superior technology for the high-speed data rate of wire-line and wireless communication systems. The OFDM has many advantages over other techniques such as its high capacity and immunity against multipath fading channels. However ,one of the main drawbacks of the OFDM system is the high-peak-to-average power ratio (PAPR) that leads the system to produce in-band distortion and out-of-band radiation because of the non-linearity and reduces its efficiency is the distortion of the signal caused at the High Power Amplifier (HPA) of a transmitter . Therefore, it is highly desirable to reduce the PAPR of an OFDM signal. For this, numerous techniques have been proposed to overcome the PAPR problem such as i) selective mapping(SLM) ii) partial transmit sequence (PTS), iii) clipping, iv) clipping and filtering. In this paper, the PTS technique was analytically reviewed as one of the important methods to reduce the high PAPR problem. Simulations are used to analyze the efficiency of the techniques used which signifies OFDM to be providing much better PAPR reduction and a better Bit Error Rate (BER) . From simulation results clipping method shows good PAPR reduction with significant amount of BER degradation. Clipping and filtering method shows slight increase in PAPR with small degradation in BER performance than Clipping method and both methods are computationally less complex. PTS provides good PAPR reduction with high computational complexity.

DrTM+B: Replication-Driven Live Reconfiguration for Fast and General Distributed Transaction Processing

Recent in-memory database systems leverage advanced hardware features like RDMA to provide transaction processing at millions of transactions per second. Distributed transaction processing systems can scale to even higher rates, especially for partitionable workloads. Unfortunately, it is challenging to sustain such high rates during live reconfiguration of partitions. In this article, we observe that state-of-the-art approaches would cause notable performance disruption under fast transaction processing. To this end, this article presents DrTM+B, a live reconfiguration approach that seamlessly repartitions data with little performance disruption to running transactions. DrTM+B uses a pre-copy-based mechanism to avoid excessive data transfer by leveraging common properties in recent transactional systems. DrTM+B's reconfiguration plans reduce data movement by preferring existing data replicas, while copying data from multiple replicas asynchronously and in parallel. It further reuses the log forwarding mechanism in primary-backup replication to seamlessly track and forward dirty database tuples and avoids iterative copying costs. To commit a reconfiguration plan in a transactional-safe way, DrTM+B designs a cooperative commit protocol for synchronization of data and state among replicas. To boost the performance during data migration, DrTM+B combines the pre-copy and post-copy schemes to propose a hybrid copy scheme. The live reconfiguration approach can also coexist with fault-tolerance mechanisms of primary-backup replication to provide high availability. Evaluation on a working system based on DrTM+R with 3-way replication using typical OLTP workloads like TPC-C and SmallBank shows that DrTM+B incurs only very small performance degradation during live reconfiguration and provides high availability. Both the reconfiguration time and the downtime are also minimal.