Analysis of a landfill cover without geomembrane using varied particle sizes of recycled concrete

Previous studies have demonstrated the effectiveness of a novel three-layer landfill cover system constructed with recycled concrete aggregates(RCAs)without geomembrane in both laboratory and field.However,no systematic investigation has been carried out to optimize the combination of the particle sizes for fine-grained RCAs(FRC)and coarse-grained RCAs(CRC)that can be used for the three-layer landfill cover system.The aim of this paper is to assist engineers in designing the three-layer landfill cover system under a rainfall of 100-year return period in humid climate conditions using an easily controlled soil parameter D10 of RCAs.The numerical study reveals that when D10 of FRC increases from 0.05 mm to 0.16 mm,its saturated permeability increases by 10 times.As a result,a larger amount of rainwater infiltrates into the cover system,causing a higher lateral diversion in both the top FRC and middle CRC layers.No further changes in the lateral diversion are observed when the D10 value of FRC is larger than 0.16 mm.Both the particle sizes of FRC and CRC layers are shown to have a minor influence on the percolation under the extreme rainfall event.This implies that the selection of particle sizes for the FRC and CRC layers can be based on the availability of materials.Although it is well known that the bottom layer of the cover system should be constructed with very fine-grained soils if possible,this study provides an upper limit to the particle size that can be used in the bottom layer(D10 not larger than 0.02 mm).With this limit,the three-layer system can still minimize the water percolation to meet the design criterion(30 mm/yr)even under a 100-year return period of rainfall in humid climates.

An Organic Solvent-Assisted Intercalation and Collection (OAIC) for Ti_(3)C_(2)T_(x) MXene with Controllable Sizes and Improved Yield

A good method of synthesizing Ti_(3)C_(2)T_(x)(MXene)is critical for ensuring its success in practical applications,e.g.,electromagnetic interference shielding,electrochemical energy storage,catalysis,sensors,and biomedicine.The main concerns focus on the moderation of the approach,yield,and product quality.Herein,a modified approach,organic solvent-assisted intercalation and collection,was developed to prepare Ti_(3)C_(2)T_(x) flakes.The new approach simultaneously solves all the concerns,featuring a low requirement for facility(centrifugation speed<4000 rpm in whole process),gram-level preparation with remarkable yield(46.3%),a good electrical conductivity(8672 S cm^(−1)),an outstanding capacitive performance(352 F g^(−1)),and easy control over the dimension of Ti_(3)C_(2)T_(x) flakes(0.47–4.60μm^(2)).This approach not only gives a superb example for the synthesis of other MXene materials in laboratory,but sheds new light for the future mass production of Ti_(3)C_(2)T_(x) MXene.

Model of homogenisation for analysing the effect of micrometre pore sizes on the elastic moduli of porous materials

A homogenisation model for analysing the effect of micrometre pore sizes on the engineering moduli of elasticity of porous materials was proposed.In the proposed model,the engineering coefficients of localization of total strains(LTS coefficients)are considered instead of the classical strain localization tensors.For a pore,these coefficients represent the ratio of the sum of the strains in the volume of the pore to the sum of the strains in the volume of the porous body.To estimate the elastic moduli of a material with an arbitrary pore size,it is sufficient to have information about the elastic moduli and the LTS coefficient of a material with one basic pore size.Then,in Eshelby's model of equivalent inclusion,a transition to LTS coefficient for material with arbitrary pore size is achieved,and its elasticity moduli are determined.The results for Young's modulus of porous titanium,with different sizes of spherical pores,completely conform with the experimental data.We have obtained a model theoretic estimate of the upper bounds of Young's modulus of porous materials with infinitely small pore size.For the spherical pores,the proposed assessment coincides with the upper limits of the Hashin-Shtrikman bounds.

An Artificial Neural Network for Estimating Sizes of Spot Welding Nuggets

Sizes of nuggets are often used to evaluate spot weld quality in production. This paper presents a neural estimator used to carry out non-destructive on-line analysis of spot weld quality in which trained ANN functions to map dynamic resistance characteristics into sizes of spot weld nuggets and results confirm the validity of neural network for this type of application.

FLOWING FILM JIGGING FUNCTION IN THE NEW″IFFC″PROCESS FOR SEPARATING MINERALS OF ULTRAFINE SIZES

The concept of the flowing film jigging was first applied to the flowing film concentration area.The flowingfilm jigging function is an important element of the new process,in jection-flowing film centrifugation(IFFC),for separating and recovering minerals of ultrafine sizes.

X-RAY MEASUREMENT OF THE GRAIN SIZES OF WSi_(2) FORMED IN COSPUTTERED W-Si FILMS

The broadening of X-ray diffraction peaks has been used successfully to measure the grain sizes of WSi_(2) in cosputtered W-Si films after annealing.The grain size of WSi_(2) increases with annealing temperature and reaches 115nm after annealing at 1000°C.The grain sizes are quite similar to that obtained by transmission electron microscope in electron beam coevaporated film and low pressure chemical vapor deposited film.

The Sizes of Sitophilus zeamais in Different Life Stage

Knowing the developmental states of stored grain insects, especially for the immature stages hidden in cereal kernel, such as Sitophilus zeamais, could be in favor of monitoring early and controlling effectively. Atlas and scale parameters on different developmental stages of S. zeamais in wheat kernel were captured and described by three-dimensional microscope of super depth of field observation. The four instars of larva, pre-pupa, pupa, new adult, old adult in kernel could be seen by dissecting the infested kernels. The length, height, and width of larva body increased with insect development and centralized the sizes corresponding to the four instars of larva. The length of larva body centralized near 554, 746, 1 462, and 2 147 μm. The height of larva body centralized about 388, 575, 847, and 1 651 μm. The width of larva body centralized near 340, 598, 798, and 1 568 μm. Head capsule width was in same size for each exuviating period, centralized near 203, 317, 535, and 603 μm, and got big sharply with the instar changed. Developmental duration of four larva instars was about 21 days reared in wheat, less than 28 days reared in maize as published. The atlas and description should be helpful for monitoring the S. zeamais development hidden in cereal kernels and designing control strategy.

Determination of Particle Sizes and Crystalline Phases on Colloidal Silicon Nanoparticle Suspensions

Particle size and crystallinity of silicon nanoparticles were determined by analyzing the optical extinction spectra of colloidal suspensions. Experimental results from these colloids were anaiyzed using Mie theory in connection with effective medium theory, in order to determine particle sizes and their internal structure with the simple technique of optical transmission spectroscopy. By modeling an effective refractive index for the particles, the crystalline volume fraction can be extracted from extinction spectra in addition to information about the size. The crystalline volume fraction determined in this way were used to calibrate the ratio of the Raman cross sections for nanocrystalline and amorphous silicon, which was found to be σc./σa = 0.

Leaching behavior of V,Pb,Cd,Cr,and As from stone coal waste rock with different particle sizes

This paper investigates the leaching behavior of heavy metals(V,Pb,Cd,Cr,and As) from stone coal waste rocks with various particle sizes using dynamic leaching experiments.The results show that the dissolved concentrations of V and As initially increased and then slightly decreased as time progressed and that the dissolved concentrations of Pb,Cd,and Cr were high in the early stage before decreasing.The particle size of the stone coal waste rocks strongly influenced the heavy metal concentration in the leaching solutions.The effects of the particle size of the stone coal waste rocks on the dissolved concentrations of V,Pb,and As decreased in the order fine fraction > medium fraction > coarse fraction,and the effects of particle size on the dissolved concentrations of Cr and Cd decreased in the order medium fraction > coarse fraction > fine fraction and coarse fraction > medium fraction > fine fraction,respectively.The quantities of heavy metals dissolved from the stone coal waste rock with fine particle sizes were observed to decrease in the order V(17104.36 μg/kg) > As(609.41 μg/kg) > Pb(469.24 μg/kg) > Cr(56.35 μg/kg) > Cd(27.52 μg/kg),and the dissolution rates decreased in the order As(2.96%) > Pb(0.93%) > V(0.35%) > Cd(0.25%) > Cr(0.01%).The specific surface area,pore size of the stone coal waste rocks,and chemical forms of heavy metals also influenced the release of heavy metals from the stone coal waste rocks.Kinetic analysis showed that the dissolution of heavy metals fundamentally agreed with the rate equation controlled by the shrinking core model.The results of this study are expected to serve as a reference for the evaluation of heavy metals contamination from stone coal waste rocks.

Microstructure, Content and in vitro Release of Brucine and Strychnine in Strychnos Nux-Vomica Powder with Different Particle Sizes

To explore the effect of particle size on the quality uniformity and in vitro release performance of Strychnos nux-vomica powder, seven samples of Strychnos nux-vomica powder with different particle sizes were prepared.Microstructures and particle sizes were analyzed, and high performance liquid chromatography(HPLC) was used to test the contents and in vitro release performances of brucine and strychnine in the samples. Results showed that the contents and the in vitro release rates of brucine(or strychnine) in different samples were different since there are different proportions of endosperms to epidermal cells in Strychnos nux-vomica powder with different particle sizes. Brucine and strychnine in each sample were promptly released in the first ten minutes and their cumulative release rates were higher than 70% after ten minutes. Eighty minutes later, the cumulative release rate tended to be a constant. Considering the quality uniformity and safety of Strychnos nux-vomica powder used as traditional Chinese medicine, it would be better to control the particle size of Strychnos nux-vomica powder between 100 and 140 mesh in which the maximum cumulative release rate in vitro of brucine and strychnine can be relatively low within this range.

Study on Cutting Force,Cutting Temperature and Machining Residual Stress in Precision Turning of Pure Iron with Different Grain Sizes

Pure iron is one of the difficult-to-machine materials due to its large chip deformation,adhesion,work-hardening,and built-up edges formation during machining.This leads to a large workpiece deformation and challenge to meet the required technical indicators.Therefore,under varying the grain size of pure iron,the influence of cutting speed,feed,and depth of cut on the cutting force,heat generation,and machining residual stresses were explored in the turning process to improve the machinability without compromising the mechanical properties of the material.The experimental findings have depicted that the influence of grain size on cutting force in the precision turning process is not apparent.However,the cutting temperature and residual stress of machining fine-grain iron were much smaller than the coarse grain at all levels of cutting parameters.

Effect of Pelleted Total Mixed Ration of Different Particle Sizes on Production Performance and Serum Biochemical Index of Fattening Hainan Black Goats

[Objective] The paper to investigate the effects of pelleted total mixed ration of different particle size on production performance and serum biochemical index of fattening Hainan black goats.[Method] Thirty-six fattening Hainan black goats with the same genetic backgrounds and similar initial weight of(19.02±0.22) kg were randomly divided into three treatments. Goats were fed with Juncao+concentrate(control group), pel-leted total mixed ration I(particle size 6 mm, experimental group I) and II(particle size 5 mm, experimental group II), respectively. The trial lasted 45 d.[Result](1) The final weight and daily gain of experimental group II were significantly higher than those of control group( P<0.05), and the daily gain of experimental group II was also higher than that of experimental group I(P<0.05);the feed intake of experimental group II was markedly higher than that of control group(P<0.05), but was significantly lower than that of experimental group I(P<0.05). The feed/gain ratio of experimental group II was significantly lower than those of control group and experimental group I(P<0.05).(2) The feed gain cost of experimental group II was markedly lower than that of control group(P<0.05), but the gross profit was significantly higher than those of control group and experimental group I(P<0.05).(3) Compared with the control group, the serum total protein content of experimental group II increased markedly( P<0.05) while the urea nitrogen level decreased(P>0.05).[Conclusion] The pelleted total mixed ration with the particle size of 5 mm obtained better fattening ef-fect, and obviously improved the serum total protein level.

BUBBLE SIZES AND HOLDUP STRUCTURE IN BUBBLE COLUMNS DETERMINED BY DYNAMIC GAS DISENGAGEMENT

A new model for determining bubble size distributions in bubble columns by the dynamic gasdisengagement(DGD)technique is developed.It is based on an idea of non-uniform steady statedirstribution of bubble dispersion.Interpreting the axial non-uniformity,this model gives axial gasholdup distributions.If assuming an axially homogeneous dispersion,a radial gas holdup distributioncan be obtained.The Sauter mean diameters or specific interfacial areas for several systems areestimated by the technique.The results for an air-water system agree with those measured by afive-point conductivity probe technique.The obtained axial gas holdup distributions agree well withreported measurements and the radial gas holdup distributions are also reasonable.

Effects of piperacillin synthesis on the infterfacial tensions and droplet sizes

Piperacillin is a polar organic substance,and can reduce the interfacial tension of oil and water when dissolved in water.In this study,changes in dichloromethane–water interfacial tensions and microdroplet sizes during piperacillin synthesis from an aqueous solution of ampicillin and dichloromethane solution of 4-ethyl-2,3-dioxo-1-piperazine carbonyl chloride(EDPC)were observed using a pendent drop technique and a coaxial ring tube system with embedded high-speed camera,respectively.It was found that the rapid N-acylation reaction caused the piperacillin at the interface to synthesize rapidly and diffuse out slowly,resulting in the interfacial tension decreased from 19.5 m N·m-1 to 7.2 m N·m-1 rapidly and then increased slowly as the concentrations of ampicillin and EDPC were 0.05 mol·L-1 and 0.1 mol·L-1.Meanwhile,the increase in the concentration of EDPC increased the peak concentration of piperacillin at the interface,and the addition of ethyl acetate to the ampicillin solution promoted mass transfer and reduced the aggregation of piperacillin effectively.During synthesis,the interfacial tension decreased,leading to a change in droplet sizes in the micro-reaction system.The two-phase reaction was carried out in a coaxial ring tube,with ampicillin and EDPC solutions as continuous and dispersed phases,respectively.The reaction reduced the dripping flow area,and the addition of ethyl acetate to the ampicillin solution slightly affected the division of the flow pattern.Under the same flow conditions,the droplet sizes of the reaction group were smaller than those of the no reaction group.The experimental results demonstrated that the increase of the continuous phase,decrease in the dispersed phase flow rate,or increase in EDPC concentration making droplet sizes smaller,and the addition of ethyl acetate slightly affected droplet sizes.These findings are important for the design and optimization of piperacillin synthesis reactors.

The Interaction between Microcapsules with Different Sizes and Propagating Cracks

The microcapsule-contained self-healing materials are appealing since they can heal the cracks automatically and be effective for a long time.Although many experiments have been carried out,the influence of the size of microcapsules on the self-healing effect is still not well investigated.This study uses the two-dimensional discrete element method(DEM)to investigate the interaction between one microcapsule and one microcrack.The influence of the size of microcapsules is considered.The potential healing time and the influence of the initial damage are studied.The results indicate that the coalescence crack is affected by the size of holes.The elastic modulus,the compressive strength and the coalescence stress decrease with the rising radius of holes.The initial damage in experiments should be greater than 95%of the compressive strength to enhance the self-healing effect.The large microcapsules require slight initial damage.Both a new type of displacement field near the crack and a new category of coalescence crack are observed.The influence of sizes of holes on the cracking behavior of concrete with a circular hole and a pre-existing crack is clarified.

Enlarging grain sizes for efficient perovskite solar cells by methylamine chloride assisted recrystallization

The quality of MAPbI3 film prepared by solvent engineering process highly depends on environment and antisolvent control.Here,we provided a simple methylamine chloride(MACl)solution treatment using a two-step process to enlarge the perovskite crystal grain sizes to more than 1 lm.Other than treatment on the film surface,the MACl solution diffuses into the MAPbI_(3) films to assist the recrystallization of small crystal at the bottom of perovskite film.The imitative contact between perovskite and substrate is formed.Meanwhile,the enlargement of grain size and ten times enhancement of crystalline reduce trap-assisted recombination of perovskite films.Thus,the significant improvement of cell efficiency of 20.89%as well as device stability is obtained with the MACl treatment.

Natural regeneration in logging gaps of different sizes in Subri River Forest Reserve(Ghana)

Subri River Forest Reserve(SR)is the most extensive forest area in Ghana with an accompanying rich floral species.Over the years,logging from both legally prescribed and illegal operations remain the predominant forest disturbance in SR.Gap creation following logging is crucial in determining tree species composition and diversity.Hence,the study evaluated the composition and diversity of naturally regenerated tree species in logging gaps of different sizes and,again examined the roles of these tree species in fulfilling the economic and ecological agenda of sustainable forest management after logging in SR.Twelve gaps were randomly selected:4 each were grouped into small size(≤200 m^(2)),medium size(201–300 m^(2)),and large size(≥300 m^(2)).Data were gathered from 1 m^(2) circular area at gap centres and repeatedly inside 1 m width strip along 20 m individual N-S-E-W transects.Species diversity differed significantly between gap sizes.Higher diversity indices were measured in large size gaps.Gap sizes shared similar species.There were significant differences among various height groupings of tree species across all three gap sizes.Pioneers preferred medium to large size gaps,while shadetolerant tree species preferred small size gaps for their abundance.Vulnerable and Lower Risk Near Threatened tree species under Conservation Status and,Premium and Commercial tree species under Utilisation Status preferred small size gaps for their proliferation and conservation.Therefore,we recommend the single tree-based selective logging for ensuring creations of small to medium size(200–300 m^(2))gaps through adjustments to the logging permit process,revision of Allocation Quota Permit,strict adherence to the 40-year polycyclic selection system,along with more dedicated enforcement and monitoring.Changes along these protocols would tremendously facilitate natural regeneration of different suites of timber species resulting in the improvement of the overall biodiversity conservation associated with the forest,more sustainable forest harvests and more income to those who receive permits.

Improved Algebraic Model for Serial Production Lines with Limited Buffer Sizes

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Effect of Temperature on the Carbon, Nitrogen, and Phosphorus Nutrient Budgets of Steelhead Trout (Oncorhynchus mykiss) with Different Sizes

This study was performed to evaluate the effect of temperature on the carbon(C),nitrogen(N),and phosphorus(P)nu-trient budgets of adult steelhead trout(Oncorhynchus mykiss)with different body sizes.A complete two-factor experiment was con-ducted at four temperatures,i.e.,9(T9),13(T13),16(T1℃℃℃6),and 19(T19);and three body sizes,℃i.e.,0.65 kg±0.02 kg(S1),1.22 kg±0.06 kg(S2),and 2.05 kg±0.09 kg(S3).The following properties of steelhead trout were determined:C,N,and P nutrient budgets;feed intake rate;fecal production rate;oxygen consumption rate;ammonia excretion rate;phosphorus excretion rate;scope of the growth of C,N,and P;and absorption efficiency of C,N,and P.Results showed no significant interaction between temperature and body size in terms of the nutrient budgets of steelhead trout.However,temperature and body size played important separate roles in the nutrient budgets except for the absorption efficiency of nitrogen.The feed intake rate,fecal production rate,ammonia excretion rate,phosphorus excretion rate,and scope of the growth of C,N,and P were the highest in the T16 treatments.The absorption effi-ciency of C and P decreased as temperature increased.Nonlinear multiple regression results indicated that 15 was the approximate℃optimal temperature for the feeding and growth of steelhead trout.The feed intake rate,fecal production rate,oxygen consumption rate,ammonia excretion rate,phosphorus excretion rate,and scope of the growth of C,N,and P per unit of the body weight of fish decreased as body size increased.The absorption efficiency of C increased as body weight increased,and the absorption efficiencies of P in the S2 and S3 treatments were significantly higher than those in the S1 treatment.During the culture of steelhead trout,the daily ratio should be adjusted with changes in the temperature and body size of fish.Furthermore,managers should focus on the risk of hypoxia at high water temperatures.

Sample sizes based on three popular indices of risks

Sample size justification is a very crucial part in the design of clinical trials. In this paper, the authors derive a new formula to calculate the sample size for a binary outcome given one of the three popular indices of risk difference.The sample size based on the absolute difference is the fundamental one, which can be easily used to derive sample size given the risk ratio or OR.