Magnitude Of Decrease Research Articles

Effects of Proteins and Mineral Ions on the Physicochemical Properties of 1,3-Dioleoyl-2-Palmitoylglycerol Emulsion to Mimic a Liquid Infant Formula.

Proteins and minerals in infant formula not only serve as nutrients, but also have important effects on the physical and chemical stability of emulsions. In this study, calcium carbonate (0 or 9.08 mM) and potassium chloride (0 or 15.96 mM), as representatives of divalent and monovalent minerals, were added to 1,3-dioleoyl-2-palmitoylglycerol (OPO) emulsions in different ratios (10:0, 9:1, 6:4, 5:5, and 0:10) of whey protein isolate (WPI) and sodium caseinate (CN). The influence of proteins and minerals on emulsion stability was investigated by analyzing particle size, zeta potential, creaming index, rheological properties, storage stability, and lipid oxidation. 1,3-dioleoyl-2-palmitoylglycerol (OPO) emulsions could be destabilized by adding Ca2+, as shown by the increase in particle size index, creaming index, and the decrease in zeta potential magnitude. Divalent ions could affect the electrostatic interactions between lipid droplets and the interactive effects of ion surface adsorption. In addition, the effect of different protein ratios on the physical stability of emulsions was not significant under the same ion-type conditions. In terms of chemical stability, higher oxidized values were found in emulsions stabilized with only CN than in those containing WPI. Our study showed that protein ratios and minerals played an important role in the stability of OPO emulsions, which might provide a reference for the development and utilization of liquid infant formula.

Nanosecond laser ablation threshold of liquid tin microdroplets

The laser ablation threshold is an important parameter that governs the response of materials to intense laser irradiation. Here we study the ablation threshold of liquid tin, by irradiating tin microdroplets with nanosecond laser pulses having finely controlled temporal shape and duration. We use the time-dependent reflection from the droplet as the main observable, which exhibits a sharp decrease in magnitude at a given time instance that depends on the laser intensity. This moment marks the generation of a plasma that strongly absorbs the following incident laser light, rapidly expands, and thereby sets in motion the remainder of the liquid droplet. We find an inverse-square dependence of this plasma-onset time on laser intensity and attribute this scaling to the presence of one-dimensional heat diffusion during irradiation. This scaling and its one-dimensional thermal origin is strongly established in literature and follows from a square-root scaling of the thermal diffusion depth with time. Our experiment unambiguously shows that this scaling law holds for our specific case of nanosecond laser impact on tin microdroplets. The results presented in this work are of particular interest to target preparation and metrology in extreme-ultraviolet sources utilizing tin microdroplet targets.

Ultrafast Anisotropic Evolution of Photoconductivity in Sb2Se3 Single Crystals.

The antimony chalcogenide crystals are composed of quasi-one-dimensional [Sb4X6]n ribbons, which lead to strong anisotropic optical and electronic properties. An attempt to exploit photoconductivity anisotropy in the device fabrication may introduce a rewarding strategy to propel the development of the antimony chalcogenide solar cells. To achieve this, understanding of the dynamic evolution of the photoconductivity anisotropy is required. Here, the photoconductivities along different lattice directions in an antimony selenide single crystal are investigated by time-resolved terahertz spectroscopy. We find that electron trapping results in a variation of the photoconductivity anisotropy accompanied by a decrease in the photoconductivity magnitude, while electron-hole recombination only reduces the magnitude but does not affect the anisotropy. Therefore, measuring the temporal evolution of photoconductivity anisotropy can provide a wealth of information regarding the nature of the photocarrier and also render a probe to selectively evaluate the photoconductivity decay mechanisms.

Vertical intertidal variation of organic matter stocks and patterns of sediment deposition in a mesotidal coastal wetland

Tidal coastal wetlands, common home to seagrass and salt marshes, are relevant carbon sinks due to their high capacity to accumulate and store organic carbon in their sediments. Recent studies demonstrated that the spatial variability of this organic carbon within the same wetland system can be significant. Some of the environmental drivers of this spatial variability remain understudied and the selection of the most relevant ones can be context dependent. Here we investigated the role of bed elevation, hydrodynamics, and habitat type (salt marsh and seagrass) on the organic matter (OM) net deposition-resuspension rate and superficial sedimentary stocks (top 5 cm) at the tidal wetlands of the Ria Formosa, a mesotidal coastal lagoon in South Portugal. Results showed that two vectors of spatial variation need to be considered to describe the intertidal sedimentary OM stocks: the bed elevation that imposes a decrease of the hydroperiod and thus the change of habitat from the lower seagrass Z. noltei to the upper saltmarsh S. maritimus, and the horizontal spatial variation along the secondary channels of the lagoon that imposes a decrease in the current flow velocity magnitude. The multiple linear regression analyses, using data from 40 sampling points, explained 59% of the variation of the superficial sedimentary stocks of OM in salt marshes and seagrasses of the Ria Formosa lagoon and revealed that stocks generally decrease with elevation, yet with variation among sites and habitats. It was also found that the decrease of the OM net deposition-resuspension rate with bed elevation was exponential. Our study emphasizes the importance of considering multiple environmental drivers and spatial variation for regional estimations of organic matter (and organic carbon) sedimentary stocks in coastal wetlands.

Locomotor Adaptation Deficits in Older Individuals With Cognitive Impairments: A Pilot Study.

Gait dysfunction and fall risk have been well documented in people with Alzheimer's Disease (AD) and individuals with mild cognitive impairment (MCI). Normal locomotor adaptation may be an important prerequisite for normal and safe community walking function, especially in older adults with age-related neural, musculoskeletal, or cardiovascular changes and cognitive impairments. The split-belt walking task is a well-studied and robust method to evaluate locomotor adaptation (e.g., the ability to adjust stepping movements to changing environmental demands). Here, we capitalized on the split-belt adaptation task to test our hypothesis that a decreased capacity for locomotor adaptation may be an important contributing factor and indicator of increased fall risk and cognitive decline in older individuals with MCI and AD. The objectives of this study were to (1) compare locomotor adaptation capacity in MCI and AD compared to healthy older adults (HOA) during split-belt treadmill walking, and (2) evaluate associations between locomotor adaptation and cognitive impairments. Our results demonstrated a significant decrease in split-belt locomotor adaptation magnitude in older individuals with MCI and AD compared to HOA. In addition, we found significant correlations between the magnitude of early adaptation and de-adaptation vs. cognitive test scores, demonstrating that individuals with greater cognitive impairment also display a reduced capacity to adapt their walking in response to the split-belt perturbation. Our study takes an important step toward understanding mechanisms underlying locomotor dysfunction in older individuals with cognitive impairment.

Plausible presynaptic effects of opioids on pontine inspiratory circuits: New insights from a joint neural biomechanical model

Administration of opioids significantly effects tidal volume, respiratory rate, and blunts CO2 responsiveness. The precise neural mechanisms that determine the respiratory depressant effects of opioids are controversial. One hypothesis is that mu‐opioid agonists hyperpolarize neurons located in the pons and this action prolongs inspiratory cycle duration. We tested the plausibility of this hypothesis by employing a neuromechanical model of the respiratory control system. We targeted medullary inspiratory neuron axon terminals that influence 4 neuronal populations within the pons that had an inspiratory component to their discharge (inspiratory (I), expiratory/inspiratory (EI), rostral inspiratory/expiratory (rIE), and caudal inspiratory/expiratory (cIE)) neurons). We systematically decreased the conductance of these synapses by 25, 50, 75 and 100 percent and monitored the effect on the respiratory motor pattern. Simulations revealed that decreasing the conductance of synapses from medullary inspiratory neurons to neuronal populations in the pons altered the breathing pattern. In general, a reduction in synaptic conductance from medullary inspiratory neurons to each of the 4 pontine neuron populations decreased their excitability. Decreasing the synaptic conductance from the medullary inspiratory decrementing (I‐Dec) population to the: 1) I pons population resulted in a decrease in phrenic burst frequency and a decrease in the Inspiratory‐Driver (I‐Driver) population excitability, 2) EI pons population resulted in a decrease in I pons excitability and phrenic neurogram magnitude, 3) rIE population did not reveal significant changes in the breathing pattern from control, and 4) cIE population resulted a decrease in I‐Driver population excitability, phrenic neurogram amplitude and phrenic burst frequency. Decreasing conductance of synapses from the inspiratory augmenting (I‐Aug) population to the I pons, cIE, or rIE populations resulted in decreases in phrenic neurogram magnitude. Our simulation data support the plausibility of presynaptic effects of opioids within the pontine respiratory group that induce respiratory depression. Further, these presynaptic effects can induce selective alterations in inspiratory drive and/or breathing cycle timing.

A Short Note on the Aftershock Duration of Strong to Major Himalayan Earthquakes

Abstract Earthquakes of M ≥ 5 tend to be locally damaging, specifically when these are the aftershocks of larger earthquakes, as the main shock would have weakened the structures. For the rescue operations and general well-being of the local residents, it is helpful if an estimate is available as to how long M ≥ 5 aftershocks would continue to occur. Earthquakes M ≥ 6.5 tend to be followed by aftershocks of M ≥ 5. In this study, aftershock sequences of seven earthquakes of magnitude M ≥ 6.5 were analyzed. Six among these are in the Himalayan region and the remaining one is in the near vicinity in China. The analysis suggests that the number of M ≥ 5 aftershocks and the duration of their occurrence decrease with the decrease of the mainshock magnitude. For the 2008 Sichuan earthquake of M 7.9 there were 136 M ≥ 5 aftershocks, while for 1975 Kinnaur earthquake of M 6.8 there were only 9. The aftershock duration of the Himalayan region earthquakes obeys the exponential law T = AecM, where the A and c are constants associated with regional fault settings. This relation is helpful in providing an estimate of the time for which M ≥ 5 aftershock activity would continue after the occurrence of a M ≥ 6.5 earthquakes.

On the action mechanism of lignosulfonate plasticizer in alkali-activated slag-based system

Workability improvement of alkali-activated materials by common plasticizers used for ordinary Portland cement is usually an issue, but certain effectiveness is often found for lignosulfonate-based plasticizers (LS), especially for activation with sodium hydroxide (its silicate modulus considered as zero). Therefore, the action of LS depending on the silicate modulus of the activator (0, 0.10, 0.25, 0.50) was studied in this paper, using non-traditional oscillation strain sweep tests. The results showed that LS works for silicate moduli of 0 and 0.10 especially in terms of great reduction in the viscoelastic moduli due to a significant decrease in zeta potential magnitude. However, LS had a marginal effect for the silicate moduli of 0.25 and 0.50, which was attributed to the competitive adsorption of LS and silicates from waterglass onto the slag grains. Although splitting of LS chains in NaOH was proven using X-ray photoelectron spectroscopy, electrostatic repulsion of smaller fragments is preserved.

Photothermal and energy performance of an innovative roof based on silica aerogel-PCM glazing systems

The glazing systems are considered as the critical components in terms of the building energy consumption owing to the undesired insulation performance and poor thermal inertial mass. To overcome those challenges, the glazing systems integrated with silica aerogel and PCM (SA-PCM) are confirmed as a promising technology to improve photothermal performance. However, the inevitable conflict remains between the energy saving and daylighting performance when the PCM and silica aerogel are filled into two different layers. Therefore, an innovative roof based on SA-PCM glazing systems is proposed, in which the original PCM layer is divided into five cavities for filling PCM and air. A numerical model to investigate the thermal performance and energy efficiency of the innovative roof is developed. The evaluation of the thermal performance of the innovative roof is conducted by the indicators of temperature decrement factor and temperature time lag, while the energy efficiency is evaluated by the total heat loss through the inner surface of the innovative roof. To evaluate the optical performance of the innovative roof, the dynamic optical properties (transmittance, absorptance, and reflectance) are obtained in conditions of different PCM fill ratios. The photothermal and energy performance of the innovative roof are investigated over a 24-hour period in the severe cold region of the city Daqing (China). The results show that the thermal performance of the innovative roof is improved with the addition of PCM amount embodied in the decrease in magnitude and the increase in phase shift of temperature waves on the inner surface. Besides, both the transmittance and absorptance of the innovative roof change significantly along with the PCM fill ratio over the course of the day, while the change in reflectance is slight. Additionally, the optimal energy performance of the innovative roof occurs at 80% fill ratio of PCM, in which the total heat loss and the energy saving rate account for 2595 kJ/m2·d-1 and 11.37%, respectively. Based on the principle of prioritizing the energy efficiency while considering the demand for light transmission properties of the innovative roof, the fill ratio of PCM is recommended as 60%.

Efficient modeling of particle transport through aerosols in GEANT4

A new method for efficiently simulating particle transport through explicit realizations of aerosols is presented. By voxelizing the aerosol and lazily generating ‘droplets’ voxel-by-voxel only when a voxel could have a relevant ‘droplet’ to the transport at hand, order of magnitude decreases in simulation time and memory can be achieved over other similarly explicit simulations while achieving statistically equivalent results. This is demonstrated in a range of simulations in which 50 MeV protons are shot through aerosols consisting of liquid water droplets with varying radius, number density, and shape. In these simulations, the presented model displays 1−2 order of magnitude decreases in simulation time and ∼1 order of magnitude decrease in simulation memory when compared to the benchmark method; proportionally larger decreases are expected for even larger droplet radii. This increased computational efficiency enables simulation of a range of aerosol-based experiments at levels of accuracy that would previously be prohibitive in time and/or memory. The described method has been included in the simulation software GEANT4, and we hope that it will be a valuable tool for quickly and accurately simulating aerosol-based experiments.

Changes in tidal asymmetry in the German Wadden Sea

The recent morphological development of the German Wadden Sea (North Sea, Europe) has been characterized by expanding intertidal flats and deepening, narrowing tidal channels at declining subtidal volume. This study analyzes the effect of these changes on tidal asymmetry, based on numerical modeling with high-resolution bathymetry data, and discusses possible adaptations of the import and export behavior in intertidal systems. As common descriptors of tidal asymmetry may show a high spatial variability in bathymetrically complex intertidal systems, we develop a novel subregion averaging approach for a more robust trend estimation. Our data reveal a statistically significant decrease in flood and flood current duration in the period from 1996 to 2016 resulting in declining flood dominance or enhanced ebb dominance in most tidal basins of the German Wadden Sea. Mean and peak current asymmetry also indicate significant decreases in mean flood current magnitude. We relate decreasing flood dominance mostly to local bathymetric volume changes rather than tidal amplitude. However, it appears likely that the sum of local effects facilitates the adaptation of regional tidal dynamics which affects especially the northern German Bight. This regional shift is explained by the deceleration of rising tides due to increased friction on laterally expanded intertidal flats and decreased subtidal channel volume. The decrease in flood or increase in ebb dominance, respectively, indicates that the recent trend of sediment accretion in Wadden Sea areas may cease soon.

Sevoflurane-Induced Apoptosis in the Mouse Cerebral Cortex Follows Similar Characteristics of Physiological Apoptosis.

General anesthetics are capable of inducing neuronal apoptosis during the rapid synaptogenesis of immature mammalian brains. In this vulnerable time window, physiological apoptosis also occurs to eliminate excess and inappropriately integrated neurons. We previously showed that physiological and ketamine-induced apoptosis in mouse primary somatosensory cortex (S1) followed similar developmental patterns. However, since sevoflurane is more widely used in pediatric anesthesia, and targets mainly on different receptors, as compared with ketamine, it is important to determine whether sevoflurane-induced apoptosis also follows similar developmental patterns as physiological apoptosis or not. Mice at postnatal days 5 (P5) and P9 were anesthetized with 1.5% sevoflurane for 4 h, and the apoptotic neurons in S1 were quantitated by immunohistochemistry. The results showed that sevoflurane raised the levels of apoptosis in S1 without interfering with the developmental patterns of physiological apoptosis. The cells more vulnerable to both physiological and sevoflurane-induced apoptosis shifted from layer V pyramidal neurons at P5 to layers II–IV GABAergic neurons by P9. The magnitude of both sevoflurane-induced and physiological apoptosis was more attenuated at P9 than P5. To determine whether the Akt-FoxO1-PUMA pathway contributes to the developmental decrease in magnitude of both physiological and sevoflurane-induced apoptosis, Western blot was used to measure the levels of related proteins in S1 of P5 and P9 mice. We observed higher levels of antiapoptotic phosphorylated Akt (p-Akt) and phosphorylated FoxO1 (p-FoxO1), and lower levels of the downstream proapoptotic factor PUMA in control and anesthetized mice at P9 than P5. In addition, the Akt-FoxO1-PUMA pathway may also be responsible for sevoflurane-induced apoptosis. Together, these results suggest that magnitude, lamination pattern and cell-type specificity to sevoflurane-induced apoptosis are age-dependent and follow physiological apoptosis pattern. Moreover, The Akt-FoxO1-PUMA pathway may mediate the developmental decreases in magnitude of both physiological and sevoflurane-induced apoptosis in neonatal mouse S1.

Degrees of circular polarization for the electromagnetic waves induced by electric point dipoles

An electric point dipole is the simplest model for emitters, antennas, and other nanostructures. For a dipole sufficiently small in comparison to the wavelength of the radiated electromagnetic wave, its electric-field intensity and Poynting vector are fully understood. Firstly, both decrease in magnitude with increasing radial distance from the dipole location. Secondly, the Poynting vector increases in magnitude with the sinusoid squared of the polar angle measured from the dipolar axis. We will consider here the degree of circular polarization (CP) of the electromagnetic wave induced by an electric point dipole. Resultantly, we learned that the near-perfect CP states form a pair of hollow-cylindrical surfaces. The radius of those surfaces designating near-perfect CP states is approximately one wavelength detached from the dipolar axis. However, these pictures are appreciably altered for the electromagnetic field induced by an array of electric point linear dipoles.

TAP: targeting and analysis pipeline for optimization and verification of coil placement in transcranial magnetic stimulation

Objective. Transcranial magnetic stimulation (TMS) can modulate brain function via an electric field (E-field) induced in a brain region of interest (ROI). The ROI E-field can be computationally maximized and set to match a specific reference using individualized head models to find the optimal coil placement and stimulus intensity. However, the available software lacks many practical features for prospective planning of TMS interventions and retrospective evaluation of the experimental targeting accuracy. Approach. The TMS targeting and analysis pipeline (TAP) software uses an MRI/fMRI-derived brain target to optimize coil placement considering experimental parameters such as the subject’s hair thickness and coil placement restrictions. The coil placement optimization is implemented in SimNIBS 3.2, for which an additional graphical user interface (TargetingNavigator) is provided to visualize/adjust procedural parameters. The coil optimization process also computes the E-field at the target, allowing the selection of the TMS device intensity setting to achieve specific E-field strengths. The optimized coil placement information is prepared for neuronavigation software, which supports targeting during the TMS procedure. The neuronavigation system can record the coil placement during the experiment, and these data can be processed in TAP to quantify the accuracy of the experimental TMS coil placement and induced E-field. Main results. TAP was demonstrated in a study consisting of three repetitive TMS sessions in five subjects. TMS was delivered by an experienced operator under neuronavigation with the computationally optimized coil placement. Analysis of the experimental accuracy from the recorded neuronavigation data indicated coil location and orientation deviations up to about 2 mm and 2°, respectively, resulting in an 8% median decrease in the target E-field magnitude compared to the optimal placement. Significance. TAP supports navigated TMS with a variety of features for rigorous and reproducible stimulation delivery, including planning and evaluation of coil placement and intensity selection for E-field-based dosing.

Use of Electromagnetic Radiation (EMR) in Preservation of Fruit Juices

This study shows the bactericidal effect of Electromagnetic Field on fruit juice microbes. Short shelf-life period of fruit juice caused by spoilage organisms has limiting factor for its economy value. The Eighteen microorganisms isolated from both fresh and spoilt fruit samples (Pineapple and Apple), and identified during the study include, twelve (12) bacteria and Six (6) fungi, out of which only the bacterial isolates were exposed to electromagnetic field of 0mG, 500mG, and 5000mG for thirty minutes. The bacteria species were Leuconostoc mesentroides, Bacillus species, Lactobacillus brevis, Microbacterium species, Clostridium species, Bacillus cereus, Acetobacter aceti, and Staphylococcus aureus. The Gram negative bacteria isolates were Erwinia carotovora, Erwinia ananas, and Proteus species. Exposure of the isolates to an electromagnetic field of 0mG, 500mG and 5000mG showed a decrease in some electromagnetic field magnitude. This study shows reduction in growth range among most bacterial species tested at 500mG electromagnetic radiation exposure, but the growth of many of these bacterial species were triggered at 5000mG electromagnetic radiation exposure. This may mean an initiation of: adaptation mechanism, growth mechanism in some microorganism, and sugar content of the fruit juice from which they are being isolated. The exposure of the bacteria to electromagnetic field elicited detectable responses therefore depends on the adaptation mechanism of each bacteria and sugar content of the fruit from which it is being isolated from. Thus, future research can be done to optimize the limits specified for target microbes that are strength and frequency of this EMF in diseases control.

Resurgence increases with repetition

Resurgence refers to a behavioral process in which a recent response is extinguished (or reinforcement conditions worsen) and a previously extinguished response recurs. In previous research, resurgence has been reliably produced when the resurgence procedure is repeated. Changes in the degree of increase of the resurging response across iterations of the procedure have been inconsistent, however, with some studies showing increases and some showing no changes or decreases in resurgence magnitude. The present study examined the nature of resurgence across repeated iterations of the conventional resurgence procedure by exposing four pigeons to the resurgence procedure six times in succession. In the first condition of the resurgence procedure, pecks on one key (e.g., the left) were reinforced under a variable-interval (VI) 30-s schedule. In the second condition pecks on that key were extinguished, and pecks on another key (e.g., the right) were reinforced under the same schedule. In the final condition there were no programmed consequences for either response. Resurgence was observed in 21 of 24 opportunities (87.5%). Iteration-over-iteration increases in resurgence were observed in 15 of 20 opportunities (75.0%), and this increase was found to be statistically significant. These findings demonstrate that, under certain conditions, resurgence generally increases in magnitude with repeated exposure to the procedures that generate it.

Across the adult lifespan the ipsilateral sensorimotor cortex negative BOLD response exhibits decreases in magnitude and spatial extent suggesting declining inhibitory control

Ipsilateral sensorimotor (iSM1) cortex negative BOLD responses (NBR) are observed to unilateral tasks and are thought to reflect a functionally relevant component of sensorimotor inhibition. Evidence suggests that sensorimotor inhibitory mechanisms degrade with age, along with aspects of motor ability and dexterity. However, understanding of age-related changes to NBR is restricted by limited comparisons between young vs old adults groups with relatively small samples sizes. Here we analysed a BOLD fMRI dataset (obtained from the CamCAN repository) of 581 healthy subjects, gender-balanced, sampled from the whole adult lifespan performing a motor response task to an audiovisual stimulus. We aimed to investigate how sensorimotor and default-mode NBR characteristics of magnitude, spatial extent and response shape alter at every decade of the aging process. We observed a linear decrease in iSM1 NBR magnitude across the whole lifespan, whereas the contralateral sensorimotor (cSM1) PBR magnitude was unchanged. An age-related decrease in the spatial extent of NBR and an increase in the ipsilateral positive BOLD response (PBR) was observed. This occurred alongside an increasing negative correlation between subject's iSM1 NBR and cSM1 PBR magnitude, reflecting a change in the balance between cortical excitation and inhibition. Conventional GLM analysis, using a canonical haemodynamic response (HR) function, showed disappearance of iSM1 NBR in subjects over 50 years of age. However, a deconvolution analysis showed that the shape of the iSM1 HR altered throughout the lifespan, with significantly delayed time-to-peak and decreased magnitude. The most significant decreases in iSM1 HR magnitude occurred in older age (>60 years) but the first changes in HR shape and timing occurred as early as 30 years, suggesting the possibility of separate mechanisms underlying these alterations. Reanalysis using data-driven HRs for each decade detected significant sensorimotor NBR into late older age, showing the importance of taking changes in HR morphology into account in fMRI aging studies. These results may reflect fMRI measures of the age-related decreases in transcollosal inhibition exerted upon ipsilateral sensorimotor cortex and alterations to the excitatory-inhibitory balance in the sensorimotor network.

Discrete element method analysis of non-linear stiffness for granular media

This contribution considers the nonlinearity of stiffness in granular materials using 3D DEM simulations, with a primary focus being placed on three issues. First, it assesses stress-dependent stiffness and density-dependent stiffness based on DEM simulations of monotonic triaxial tests. The modified formulation of hyperbolic relation based on the DEM data is generated to capture stiffness degradation, which can take the various types of an S-shaped curve due to the initial mean effective stress and the sample density. The use of various void ratio correction functions is made to remove the effect of density on the stiffness curve. DEM results reveal that inclusion of the coordination number in both forms of the void ratio function serve a better role in unifying the stiffness dataset from samples with different densities. Second, the framework of kinematic modified yielding points proposed by Jardine (1992) that identifies three main zones (i.e. linear elastic behaviour, non-linear elastic behaviour and elasto-plastic behaviour) provides a benchmark for the gap between the dynamic stiffness and the static stiffness to be studied in an effective manner. A key observation is that the dynamic shear stiffness tends to increase to a peak value before experiencing of a decrease in magnitude. Third, the investigation into the nature of energy dissipation during triaxial shearing tests is made. Several DEM simulations were performed to assess effects of the coefficient of uniformity (Cu) on the non-linear behaviour of granular materials, arriving at some key observations that: (i) a higher amount of work should be input for samples with coarse particles to attain a particular strain level; and (ii) more energy dissipation is observed for samples with a lower Cu value.

Wavelet Analysis of Dam Injection and Discharge in Three Gorges Dam and Reservoir with Precipitation and River Discharge

The Yangtze River has been the primary support of the resources and transportation of China. The Three Gorges Dam and Reservoir on the Yangtze River is one of the world’s largest dams. The influence caused by the dam and reservoir on the river system has been overwhelming and destructive. For better water resource use and flood-prevention planning, more understanding is needed regarding the dam’s impact on river discharge, regional precipitation, and frequency of extreme rainfall events. This study aims to analyze the changes in river discharge and regional precipitation records before and after the construction of the Three Gorges Dam. This research examines temporal correlations among these data by collecting daily dam injection and dam discharge records, the precipitation from ground stations, and river discharge. The time series are analyzed with the wavelet analysis. The precipitation datasets decrease in wavelet magnitude after 1998 when the dam was built in the wavelet analysis. The annual cycle, shown as a bright year line through the time range, still exists in the analysis result after 1998, but the magnitude of the annual cycle has reduced. The river discharge shows a decrease of wavelet magnitude at the three downstream locations. The possible explanation of this pattern could be the human-controlled dam discharge. The constant water level maintained in the reservoir by human control would slow down the flow speed and stabilize it.

Computational analysis of fuel saving by using porous-end configuration for a PEM fuel cell

In the present study, a novel porous-end PEMFC inspired by the characteristics of open-end and dead-end PEMFCs is proposed for fuel saving. For this purpose, a porous media region with a certain thickness is added to the outlet region of the anode channel of an open-end PEMFC. The effect of porous media thickness at the anode channel on the current density and hydrogen mass flow was numerically analyzed. Results indicate that in comparison to the base model PEMFC, the presence of porous media at the end of the anode channel of porous-end PEMFC leads to an increase in the pressure and a decrease in the velocity magnitude in the anode channel. Results illustrate that the porous-end PEMFC with t = 1 mm thickness can be an adequate choice to gain an optimum design for the porous-end configuration. This conclusion becomes more highlighted when the results give the 66.17% reduction in fuel consumption. • Porous-end PEMFC inspired by the open-end and dead-end PEMFCs is proposed. • Using porous-end PEMFC significantly increased hydrogen fuel utilization. • Using porous-end PEMFC leads to uniform pressure distribution in the anode channel. • The porous-end efficiency increases by raising the thickness of porous media.