This study seeks to establish a high-fidelity mesoscale simulation methodology that can predict the progressive damage and resultant failure of carbon fiber reinforced plastic laminates (CFRPs). In ...the proposed scheme, the plastic behavior (i.e., pre-peak nonlinear hardening in the local stress-strain response) is characterized through the pressure-dependent elasto-plastic constitutive law. The evolution of matrix cracking and delamination, which result in post-peak softening in the local stress-strain response, is modeled through cohesive zone models (CZM). The CZM for delamination is introduced through an interface element, but the CZM for matrix cracking is introduced through an extended finite element method (XFEM). Additionally, longitudinal failure, which is dominated by fiber breakage and typically depends on the specimen size, is modeled by the Weibull criterion. The validity of the proposed methodology was tested against an off-axis compression (OAC) test of unidirectional (UD) laminates and an open-hole tensile (OHT) test of quasi-isotropic (QI) laminates. Finally, sensitivity studies were performed to investigate the effect of plasticity and thermal residual stress against the prediction accuracy in the OHT simulation.
The aim of this study is to investigate the mechanical properties of noncircular carbon fiber reinforced plastics (CFRPs). For an efficient study of various CFRP microstructures, this study combines ...an extended finite element method (XFEM), a homogenization method, and a Monte Carlo method and establishes XFEM-based computational micromechanics. This scheme made it possible to simulate CFRPs having various microstructure without remeshing and resetting boundary conditions. In the verification against general circular CFRPs, it was revealed that the developed scheme has a sufficient accuracy for the prediction of the homogenized elastic constants including their stochastic nature. Finally, the effects of the cross-sectional fiber shape on the macroscopic CFRP properties were examined. Among the five fiber shapes (circular, elliptical, two-lobed, triangular, and square), the square CFRP exhibited the best transverse mechanical properties. Therefore, it was concluded that the noncircular carbon fibers have a potential to enhance the macroscopic mechanical performance of CFRPs.
Progressive damages in the open-hole compression (OHC) tests of composite laminates were experimentally and numerically studied. In the experiment, the failure mechanisms were investigated via in ...situ microscopy observation, digital image correlation, X-ray radiography, and X-ray computed tomography. Three layups were tested to examine the dependence of progressive damages on the layups. Additionally, numerical simulation was conducted to comprehensively examine the failure mechanisms. In the numerical studies, the simulation scheme, considering the plasticity, kink-band failure, multiple intra-laminar cracks, and delamination, was developed. From the experiment and simulation, it is clarified that the kink-band is initiated and propagated by the combined stress states consisting of longitudinal compression and in-plane shear around the intra-laminar cracks. Therefore, for the high-fidelity OHC simulation in various layups, it is necessary to capture the interaction between kink-band and intra-laminar cracks by considering the combined stress state in the kink-band failure criteria and modeling the multiple intra-laminar cracks.
The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) examined the short-lived drivers of climate change in current climate models. Here we evaluate the 10 ACCMIP models that ...included aerosols, 8 of which also participated in the Coupled Model Intercomparison Project phase 5 (CMIP5). The models reproduce present-day total aerosol optical depth (AOD) relatively well, though many are biased low. Contributions from individual aerosol components are quite different, however, and most models underestimate east Asian AOD. The models capture most 1980–2000 AOD trends well, but underpredict increases over the Yellow/Eastern Sea. They strongly underestimate absorbing AOD in many regions. We examine both the direct radiative forcing (RF) and the forcing including rapid adjustments (effective radiative forcing; ERF, including direct and indirect effects). The models' all-sky 1850 to 2000 global mean annual average total aerosol RF is (mean; range) −0.26 W m−2; −0.06 to −0.49 W m−2. Screening based on model skill in capturing observed AOD yields a best estimate of −0.42 W m−2; −0.33 to −0.50 W m−2, including adjustment for missing aerosol components in some models. Many ACCMIP and CMIP5 models appear to produce substantially smaller aerosol RF than this best estimate. Climate feedbacks contribute substantially (35 to −58%) to modeled historical aerosol RF. The 1850 to 2000 aerosol ERF is −1.17 W m−2; −0.71 to −1.44 W m−2. Thus adjustments, including clouds, typically cause greater forcing than direct RF. Despite this, the multi-model spread relative to the mean is typically the same for ERF as it is for RF, or even smaller, over areas with substantial forcing. The largest 1850 to 2000 negative aerosol RF and ERF values are over and near Europe, south and east Asia and North America. ERF, however, is positive over the Sahara, the Karakoram, high Southern latitudes and especially the Arctic. Global aerosol RF peaks in most models around 1980, declining thereafter with only weak sensitivity to the Representative Concentration Pathway (RCP). One model, however, projects approximately stable RF levels, while two show increasingly negative RF due to nitrate (not included in most models). Aerosol ERF, in contrast, becomes more negative during 1980 to 2000. During this period, increased Asian emissions appear to have a larger impact on aerosol ERF than European and North American decreases due to their being upwind of the large, relatively pristine Pacific Ocean. There is no clear relationship between historical aerosol ERF and climate sensitivity in the CMIP5 subset of ACCMIP models. In the ACCMIP/CMIP5 models, historical aerosol ERF of about −0.8 to −1.5 W m−2 is most consistent with observed historical warming. Aerosol ERF masks a large portion of greenhouse forcing during the late 20th and early 21st century at the global scale. Regionally, aerosol ERF is so large that net forcing is negative over most industrialized and biomass burning regions through 1980, but remains strongly negative only over east and southeast Asia by 2000. Net forcing is strongly positive by 1980 over most deserts, the Arctic, Australia, and most tropical oceans. Both the magnitude of and area covered by positive forcing expand steadily thereafter.
An earth system model (MIROC-ESM 2010) is fully described in terms of each model component and their interactions. Results for the CMIP5 (Coupled Model Inter-comparison Project phase 5) historical ...simulation are presented to demonstrate the model's performance from several perspectives: atmosphere, ocean, sea-ice, land-surface, ocean and terrestrial biogeochemistry, and atmospheric chemistry and aerosols. An atmospheric chemistry coupled version of MIROC-ESM (MIROC-ESM-CHEM 2010) reasonably reproduces transient variations in surface air temperatures for the period 1850-2005, as well as the present-day climatology for the zonal-mean zonal winds and temperatures from the surface to the mesosphere. The historical evolution and global distribution of column ozone and the amount of tropospheric aerosols are reasonably simulated in the model based on the Representative Concentration Pathways' (RCP) historical emissions of these precursors. The simulated distributions of the terrestrial and marine biogeochemistry parameters agree with recent observations, which is encouraging to use the model for future global change projections.
This study was performed to investigate the clinical characteristics of lupus enteritis in Japanese patients with systemic lupus erythematosus (SLE). A total of 481 patients with SLE admitted to our ...hospital between 2001 and 2015 were retrospectively reviewed. Diagnosis of lupus enteritis was based on the following three criteria: (1) abdominal symptoms, (2) diffuse long-segment bowel thickening and (3) a requirement for glucocorticoid therapy. Lupus enteritis was identified in 17 patients (3.5%) and there were two distinct types: small intestine-dominant and large intestine-dominant. Significant differences between the two types were noted with respect to the age, frequency of biopsy-proven lupus nephritis, frequency of rectal involvement, maximum bowel wall thickness, and requirement for steroid pulse therapy. Among patients with large intestine-dominant lupus enteritis, 60% had extra-intestinal symptoms (hydroureter, bladder wall thickening, and bile duct dilatation) that are known complications of intestinal pseudo-obstruction. Two patients with large intestine-dominant lupus enteritis developed intestinal pseudo-obstruction either before or after diagnosis of lupus enteritis. Five patients (29%) developed recurrence during a median observation period of 7.2 years (1.4–14.4 years). In conclusion, large intestine-dominant lupus enteritis resembles intestinal pseudo-obstruction and these two diseases may have a common pathogenesis.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, OILJ, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
We estimated the source-receptor relationship for surface O3 in East Asia during the early 2000s using a method that tags O3 tracers according to their region of chemical production (tagged tracer ...method) with a global chemical transport model. The estimation demonstrated the importance of intracontinental transport of O3 inside East Asia as well as of the transport of O3 from distant source regions. The model well simulated the absolute concentration and seasonal variation of surface O3 in East Asia and demonstrated significant seasonal differences in the origin of surface O3. In the cold season (October to March), more than half of surface O3 in East Asia is attributable to the O3 transported from distant sources outside of East Asia. In the warm season (April to September), most of the surface O3 is attributable to O3 created within East Asia in most areas of East Asia. In spring the contribution of domestically created O3 accounted for 20% of the surface O3 in Japan and the Korean Peninsula, 40% in the North China Plain, and around 50% in the southern part of China, and the domestic contribution increased greatly in summer. The contributions of O3 created in China and the Korean Peninsula to O3 in Japan were estimated at about 10% and 5%, respectively. We also demonstrated a large contribution (20%) from China to the Korean Peninsula. In the northern and southern parts of China, large contributions of over 10% from East Siberia and the Indochina Peninsula, respectively, were identified. The contribution from intercontinental transport increased with latitude; it was 21% in Northeast China and 13% in Japan and the Korean Peninsula in spring. As for the hourly mean of surface O3, domestically created O3 was the main contributor in most areas of East Asia, except for the low O3 class (<30 ppbv), and accounted for more than 50% in the very high O3 class (>90 ppbv). The mean relative contribution of O3 created in China to O3 in central Japan was about 10% in every class, but that created in the Korean Peninsula was significant in all except the low O3 class. We identified the substantial impact of foreign sources on Japan's ambient air quality standard in the high O3 class (60–90 ppbv) in spring.
Results of comprehensive long‐term simulations of surface all‐sky and clear‐sky ultraviolet (UV) radiation through 1960–2100 are presented. A new earth system model, MIROC‐ESM‐CHEM, is used for the ...simulation, which considers key processes that change the surface UV radiation: atmospheric dynamics and chemistry affecting ozone in the stratosphere and troposphere, aerosols and clouds in the troposphere, and changes in surface albedo with sea ice and snow cover. In contrast to previous assessments considering only the effect of long‐term change in stratospheric ozone, the simulated long‐term behavior of UV radiation in this study is strongly affected by other processes. In one of two simulations, all‐sky UV radiation in the northern midlatitudes is projected to increase in the 21st century despite the expected recovery of the stratospheric ozone layer. Reductions in aerosols and clouds are expected to overcompensate for the effect of ozone recovery. The results are sensitive to the future socioeconomic scenario, describing GHG concentrations and emissions of aerosol and ozone precursors in the troposphere. The interannual variability of UV radiation associated with the 11 year solar cycle and local processes is also discussed.
Key Points
Future all‐sky UV‐B radiation at the Earth's surface is projected by an ESM
The UV‐B is dramatically affected by the future socioeconomic scenarios
Tropospheric/stratospheric ozone, aerosols, clouds, and albedo affect the result
We present a power-efficient and reduced-complexity all-optical approach to generate high-bit rate superchannels, based on joint time-frequency multiplexing. Both optical orthogonal frequency ...division multiplexing (OFDM) and Nyquist-optical time division multiplexing (N-OTDM) signals are generated and processed using a wavelength-selective switch (WSS). We use the fractional Fourier transform (FrFT) to introduce the largest degree of flexibility in optical networking, and we experimentally demonstrate that the transmitted signal can be received either in parallel, as OFDM subcarriers, or in series, as an N-OTDM signal. Compared to conventional optical OFDM, we achieve peak to average power ratio (PAPR) reduction; compared to N-OTDM, we introduce flexible chromatic dispersion (CD) management. We successfully demonstrate a field trial experiment of 4-channel 40 Gb/s hybrid OFDM/N-OTDM transmission over the 89.2-km Japan gigabit network-extreme (JGN X) test bed, with 1 bit/s/Hz spectral efficiency.
Ozone (O3) from 17 atmospheric chemistry models taking part in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) has been used to calculate tropospheric ozone radiative ...forcings (RFs). All models applied a common set of anthropogenic emissions, which are better constrained for the present-day than the past. Future anthropogenic emissions follow the four Representative Concentration Pathway (RCP) scenarios, which define a relatively narrow range of possible air pollution emissions. We calculate a value for the pre-industrial (1750) to present-day (2010) tropospheric ozone RF of 410 mW m−2. The model range of pre-industrial to present-day changes in O3 produces a spread (±1 standard deviation) in RFs of ±17%. Three different radiation schemes were used – we find differences in RFs between schemes (for the same ozone fields) of ±10%. Applying two different tropopause definitions gives differences in RFs of ±3%. Given additional (unquantified) uncertainties associated with emissions, climate-chemistry interactions and land-use change, we estimate an overall uncertainty of ±30% for the tropospheric ozone RF. Experiments carried out by a subset of six models attribute tropospheric ozone RF to increased emissions of methane (44±12%), nitrogen oxides (31 ± 9%), carbon monoxide (15 ± 3%) and non-methane volatile organic compounds (9 ± 2%); earlier studies attributed more of the tropospheric ozone RF to methane and less to nitrogen oxides. Normalising RFs to changes in tropospheric column ozone, we find a global mean normalised RF of 42 mW m−2 DU−1, a value similar to previous work. Using normalised RFs and future tropospheric column ozone projections we calculate future tropospheric ozone RFs (mW m−2; relative to 1750) for the four future scenarios (RCP2.6, RCP4.5, RCP6.0 and RCP8.5) of 350, 420, 370 and 460 (in 2030), and 200, 300, 280 and 600 (in 2100). Models show some coherent responses of ozone to climate change: decreases in the tropical lower troposphere, associated with increases in water vapour; and increases in the sub-tropical to mid-latitude upper troposphere, associated with increases in lightning and stratosphere-to-troposphere transport. Climate change has relatively small impacts on global mean tropospheric ozone RF.
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