Effects of geogrid reinforcement in low volume flexible pavement

This paper presents findings of a study on geogrid reinforced flexible pavement in a low volume road through a three-dimensional finite element analysis. A mechanistic model was developed for geogrid reinforced flexible pavement. To analyze the behavior of pavement foundation, stress-dependent resilient modulus models were employed in both base and subgrade layers. The model also incorporated previous research findings to enhance the reliability of the analysis. During the analysis, comparisons were made to contrast the responses of low volume flexible pavement with and without geogrid. The results show geogrid reinforcement reduces critical pavement responses under traffic loading, such as vertical surface deflection, tensile strain in asphalt concrete, and compressive strain in subgrade. The study found up to 18% reduction of vertical strain at the top of subgrade and 68% reduction of tensile strain at the bottom of asphalt concrete. Also, geogrid provides confining stresses in the adjacent aggregate layer, which leads to surrounding layers becoming stiffer. Based on the results of this study, the placement of geogrid reinforcement on top of weak subgrade was found particularly effective compared to that on strong subgrade. First published online: 24 Oct 201

Permanent Pacemaker for Syncope after Heart Transplantation with Bicaval Technique

Sinus node dysfunction occurs occasionally after heart transplantation and may be caused by surgical trauma, ischemia to the sinus node, rejection, drug therapy, and increasing donor age. However, the timing and indication of permanent pacemaker insertion due to sinus node dysfunction following heart transplantation is contentious. Here, we report a case of a permanent pacemaker insertion for syncope due to sinus arrest after heart transplantation, even with a bicaval technique, which has been known to associate with few incidences of sinus node dysfunction

Application of Filters to Multiway Joins in MapReduce

Joining multiple datasets in MapReduce may amplify the disk and network overheads because intermediate join results have to be written to the underlying distributed file system, or map output records have to be replicated multiple times. This paper proposes a method for applying filters based on the processing order of input datasets, which is appropriate for the two types of multiway joins: common attribute joins and distinct attribute joins. The number of redundant records filtered depends on the processing order. In common attribute joins, the input records do not need to be replicated, so a set of filters is created, which are applied in turn. In distinct attribute joins, the input records have to be replicated, so multiple sets of filters need to be created, which depend on the number of join attributes. The experimental results showed that our approach outperformed a cascade of two-way joins and basic multiway joins in cases where small portions of input datasets were joined

Microstructure and Mechanical Properties of High-Entropy Alloy Co20Cr26Fe20Mn20Ni14 Processed by High-Pressure Torsion at 77 K and 300 K

In this work, the mechanical characteristics of high-entropy alloy Co20Cr26Fe20Mn20Ni14 with low-stacking fault energy processed by cryogenic and room temperature high-pressure torsion (HPT) were studied. X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses were performed to identify the phase and microstructure variation and the mechanical properties characterized by Vickers hardness measurements and tensile testing. Cryogenic HPT was found to result in a lower mechanical strength of alloy Co20Cr26Fe20Mn20Ni14 than room temperature HPT. Microstructure analysis by SEM and TEM was conducted to shed light on the microstructural changes in the alloy Co20Cr26Fe20Mn20Ni14 caused by HPT processing. Electron microscopy data provided evidence of a deformation-induced phase transformation in the alloy processed by cryogenic HPT. Unusual softening phenomena induced by cryogenic HPT were characterized by analyzing the dislocation density as determined from X-Ray diffraction peak broadening.11Ysciescopu

Deformation Characteristics of Ultrahigh-Strength Concrete under Unrestrained and Restrained States

As structures like skyscrapers and long-span bridges become larger, the demand for higher strength of concrete is increasing. However, research on ultrahigh-strength concrete (UHSC) is still in its infancy. In particular, UHSC is known to have a considerably higher level of autogenous shrinkage than normal strength concrete (NSC), and the possibility of cracking at an early age is very high. Therefore, in this study, shrinkage and cracking behavior of high-strength concrete (HSC), very-high-strength concrete (VHSC), and UHSC were evaluated through unrestrained shrinkage test and restrained shrinkage test (ring test). The primary experimental variables are the compressive strength level according to the water-to-binder ratio (W/B), fly ash content, and concrete specimen thickness. The experimental results demonstrated that the drying shrinkage decreased as the W/B ratio and the fly ash replacement ratio increased, and the restraint cracks appeared to be the earliest and most brittle in the UHSC with the smallest W/B. Increased concrete thickness and incorporation of fly ash were observed to inhibit crack initiation effectively

Estimating remineralized phosphate and its remineralization rate in the northern East China Sea during Summer 1997 : a snapshot study before Three-Gorges Dam construction

© The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Terrestrial, Atmospheric and Oceanic Sciences 27 (2016): 955-963, doi:10.3319/TAO.2016.01.24.01(Oc).The northern East China Sea (a.k.a., “The South Sea”) is a dynamic zone that exerts a variety of effects on the marine ecosystem due to Three-Gorges Dam construction. As the northern East China Sea region is vulnerable to climate forcing and anthropogenic impacts, it is important to investigate how the remineralization rate in the northern East China Sea has changed in response to such external forcing. We used an historical hydrographic dataset from August 1997 to obtain a baseline for future comparison. We estimate the amount of remineralized phosphate by decomposing the physical mixing and biogeochemical process effect using water column measurements (temperature, salinity, and phosphate). The estimated remineralized phosphate column inventory ranged from 0.8 to 42.4 mmol P m-2 (mean value of 15.2 ± 12.0 mmol P m-2). Our results suggest that the Tsushima Warm Current was a strong contributor to primary production during the summer of 1997 in the study area. The estimated summer (June - August) remineralization rate in the region before Three-Gorges Dam construction was 18 ± 14 mmol C m-2 d-1.T. Lee was supported by 2-Year Research Grant of Pusan National University. H.-C. Kim was partly supported by KOPRI project (PG15010). I.-N. Kim was partly supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. 2015R1C1A1A01052051). K.-T. Park was partly supported by KOPRI project (PE17010). J.-H. Kim was partly supported by the program of “Management of Marine Organisms Causing Ecological Disturbance and Harmful Effects” funded by KIMST/MOF. A.M. Macdonald’s contribution was supported by NOAA grant: #NA110AR4310063 and NSF grant: #OCE-1059881