Kind Of Dispersion Research Articles

A Bivariate Extension to Exponentiated Inverse Flexible Weibull Distribution: Shock Model, Features, and Inference to Model Asymmetric Data

The primary objective of this article was to introduce a new probabilistic model for the discussion and analysis of random covariates. The introduced model was derived based on the Marshall–Olkin shock model. After proposing the mathematical form of the new bivariate model, some of its distributional properties, including joint probability distribution, joint reliability distribution, joint reversed (hazard) rate distribution, marginal probability density function, conditional probability density function, moments, and distributions for both Y=max{X1,X2} and W=min{X1,X2}, were investigated. This novel model can be applied to discuss and evaluate symmetric and asymmetric data under various kinds of dispersion. Moreover, it can be used as a probability approach to analyze different shapes of hazard rates. The maximum likelihood approach was utilized for estimating the parameters of the bivariate model. A simulation study was carried out to assess the performance of the parameters, and it was noted that the maximum likelihood technique can be used to generate consistent estimators. Finally, two real datasets were analyzed to illustrate the notability of the novel bivariate distribution, and it was found that the suggested distribution provided a better fit than the competitive bivariate models.

A novel dichotomy model based on the traditional CCA

The Cluster-Cluster Aggregation model (CCA) was often used to simulate the aggregation of colloids, in which the rapid and slow aggregation processes of colloids can be well characterized. In practical system, the movement of particles or clusters occurs in parallel. In the CCA model, in order to facilitate computer simulation, the movement of particles or clusters is processed serially by the method of Metropolis sampling. That is, randomly selecting one particle or cluster to move randomly, colliding with other cluster in the movement, and aggregating according to certain conditions, such aggregation would usually occur between a moving cluster and a static cluster, and this process is essentially a dimerization process. Based on this idea, this study proposes a cluster dichotomy model, in which the dispersion process can be regarded as the inverse process of cluster aggregation, that is, the randomly selected cluster always breaks up into two small clusters. This kind of dispersion is called dichotomy. Based on this model, the rapid and slow dispersion processes of colloidal clusters can be simulated by setting the relevant parameters. The dichotomy model proposed in this paper can be used to study colloidal stability by coupling with the traditional CCA model.

An extraction method of dispersion curve from vertical seismic profiling data

Abstract The dispersion curve describes the relationship between velocities and frequencies. The group velocity is a kind of dispersion, which presents the velocities of the energy with different frequencies. Although many studies have shown methods for estimating group velocity from a surface wave, the estimation of group velocity from body-wave data is still hard. In this paper, we propose a method to calculate the group velocity from vertical seismic profiling (VSP) data that is a kind of body-wave data. The generalised S-transform (GST) is used to map the seismic signal to the time-frequency (TF) domain and then the group delay (GD) can be extracted from the TF domain. The GD shows the travelling time of different frequency components. The group velocity can be calculated by the GD and the distance between receivers. Unfortunately, the GD is hard to measure accurately because of the noise. Inaccurate GD introduces errors in estimating the velocity. To reduce the errors, we make use of the multiple traces and the iterative least-squares fitting to extract the relationship line between GD and depths. The slope of the line is the reciprocal of the group velocity. Two numerical examples prove the effectiveness of the method. We also derive the formula of group velocity in diffusive-viscous media. In the field data example, the dispersion intensity at different depths and the geological layers can be well matched. These examples illustrate the proposed method is an alternative method for dispersion estimation from VSP.

Synthesis, analysis and application of naphthalene sulfonic acid formaldehyde condensate

β-naphthalene sulfonic acid formaldehyde condensate is a kind of dispersant with good properties, such as wetting, emulsifying, dispersing. It is widely used as coating dispersant, dye dispersant, cement water reducer and so on. Therefore, the synthesis of naphthalene sulfonic acid formaldehyde condensate and its application performance are of great practical significance. In this paper, naphthalene sulfonic acid formaldehyde condensate was synthesized from naphthalene, concentrated sulfuric acid and formaldehyde with the ratio of naphthalene to sulfuric acid approaching 1:2, the condensation temperature ranging from 110∼120°C and the condensation time of 5.5 hours. The characteristics of groups in products were determined by IR.

Influence of sample depletion on Z-scan measurements of hydroxyl groups modified multi-walled carbon nanotubes dispersions

Hydroxyl groups modified multi-walled carbon nanotubes (MWNTs-OH) were dispersed in N, N-dimethylformamide (DMF), water and chloroform, respectively. Each kind of dispersions were poured in 1-mm, 2-mm and 5-mm quartz cuvettes, respectively. The nonlinear optical (NLO) and optical limiting properties of the dispersions were studied using open-aperture Z-scan technique at 532 nm in nanosecond regime. Results show that thick cuvette or solvents with excellent thermodynamic parameters allows efficient replenishment of MWNTs-OH in the intensely irradiated volume, leading to excellent optical limiting properties arising from the well known nonlinear scattering, while thin cuvette or solvents with poor thermodynamic parameters allows inefficient replenishment of MWNTs-OH, which even leads to false appearance of ‘saturable absorption-like’ or ‘nonlinear refraction-like’ behavior due to the depletion of the sample. The different replenishment efficiency of the dispersions with the same solvent in cuvettes of different thickness can be attributed to the different influence of viscous force near the cuvette sidewalls. This influence should also be noted in other nanomaterials sharing similar NLO mechanism to carbon nanotubes dispersions during Z-scan experiments.

Preparation of Cobalt Blue Ceramic Glaze Ink Based on Sol- Gel Method

Cobalt blue pigment precursor xerogel was prepared by sol-gel method and then calcined to obtain cobalt blue pigment by self-propagating combustion. The effect of process parameters such as pH value, metal ion concentration, dispersant, sol reaction temperature, citric acid dosage and calcination temperature on the crystalline form of cobalt blue pigment was studied. The ultrafine cobalt blue pigment obtained by the above method is used as the inorganic pigment of the blue ink, and the blue ceramic ink is prepared by a dispersion method. The effects of the milling medium size, milling time, dispersion effect of different kinds of dispersants, and solvent addition was studied. Dry gel is processed by self-propagating combustion and then calcined athigh temperature. With the calcination temperature increasing, pigment color is more bright. At 1250 ?, thegrain size of the sample is approximately 200 to 500 nm. The sample is tested by a colorimeter, and its b*value is -43.09.

ATMOSPHERIC DYNAMICS OF AIR POLLUTION DISPERSION AND SUSTAINABLE ENVIRONMENT IN NIGERIA

The basic properties of chlorine was used to determine the dispersion patterns of the recent Jos explosion. The dynamic aerosols content model was used to affirm the eight kinds of dispersion patterns discussed in this text. The location of the victims showed that the dispersion at Jos was either linear or polynomial dispersion. The dispersions are influenced by atmospheric ventilation, stagnation and recirculation. The last chlorine gas explosion follows the linear or polynomial dispersion because of the current state of aerosol loadings in Jos. The aftermath effect of this kind of dispersion may be more threatening than the initial danger due to the chemical formation of more dangerous compounds. The atmospheric conditions for the formation of toxic compound were investigated using twelve years MERRA satellite observation. The degree of freedom of methane, carbon oxide and ozone was nearly uniform for the past five years. This means the next five years or more may be threatening for life forms within the region. The installation of gas tracers within major locations in Jos was suggested to monitor the formation of dioxins in the atmosphere.

ATMOSPHERIC DYNAMICS OF AIR POLLUTION DISPERSION AND SUSTAINABLE ENVIRONMENT IN NIGERIA

The basic properties of chlorine was used to determine the dispersion patterns of the recent Jos explosion. The dynamic aerosols content model was used to affirm the eight kinds of dispersion patterns discussed in this text. The location of the victims showed that the dispersion at Jos was either linear or polynomial dispersion. The dispersions are influenced by atmospheric ventilation, stagnation and recirculation. The last chlorine gas explosion follows the linear or polynomial dispersion because of the current state of aerosol loadings in Jos. The aftermath effect of this kind of dispersion may be more threatening than the initial danger due to the chemical formation of more dangerous compounds. The atmospheric conditions for the formation of toxic compound were investigated using twelve years MERRA satellite observation. The degree of freedom of methane, carbon oxide and ozone was nearly uniform for the past five years. This means the next five years or more may be threatening for life forms within the region. The installation of gas tracers within major locations in Jos was suggested to monitor the formation of dioxins in the atmosphere.

Gaussian-mixture-model-based cluster analysis finds five kinds of gamma-ray bursts in the BATSE catalogue

Clustering methods are an important tool to enumerate and describe the different coherent kinds of Gamma Ray Bursts (GRBs). But their performance can be affected by a number of factors such as the choice of clustering algorithm and inherent associated assumptions, the inclusion of variables in clustering, nature of initialization methods used or the iterative algorithm or the criterion used to judge the optimal number of groups supported by the data. We analyzed GRBs from the BATSE 4Br catalog using $k$-means and Gaussian Mixture Models-based clustering methods and found that after accounting for all the above factors, all six variables -- different subsets of which have been used in the literature -- and that are, namely, the flux duration variables ($T_{50}$, $T_{90}$), the peak flux ($P_{256}$) measured in 256-millisecond bins, the total fluence ($F_t$) and the spectral hardness ratios ($H_{32}$ and $H_{321}$) contain information on clustering. Further, our analysis found evidence of five different kinds of GRBs and that these groups have different kinds of dispersions in terms of shape, size and orientation. In terms of duration, fluence and spectrum, the five types of GRBs were characterized as intermediate/faint/intermediate, long/intermediate/soft, intermediate/intermediate/intermediate, short/faint/hard and long/bright/intermediate.

Wave Dispersion and Basic Concepts of Peridynamics Compared to Classical Nonlocal Damage Models

The spectral approach is used to examine the wave dispersion in linearized bond-based and state-based peridynamics in one and two dimensions, and comparisons with the classical nonlocal models for damage are made. Similar to the classical nonlocal models, the peridynamic dispersion of elastic waves occurs for high frequencies. It is shown to be stronger in the state-based than in the bond-based version, with multiple wavelengths giving a vanishing phase velocity, one of them longer than the horizon. In the bond-based and state-based, the nonlocality of elastic and inelastic behaviors is coupled, i.e., the dispersion of elastic and inelastic waves cannot be independently controlled. In consequence, the difference between: (1) the nonlocality due to material characteristic length for softening damage, which ensures stability of softening damage and serves as the localization limiter, and (2) the nonlocality due to material heterogeneity cannot be distinguished. This coupling of both kinds of dispersion is unrealistic and similar to the original 1984 nonlocal model for damage which was in 1987 abandoned and improved to be nondispersive or mildly dispersive for elasticity but strongly dispersive for damage. With the same regular grid of nodes, the convergence rates for both the bond-based and state-based versions are found to be slower than for the finite difference methods. It is shown that there exists a limit case of peridynamics, with a micromodulus in the form of a Delta function spiking at the horizon. This limit case is equivalent to the unstabilized imbricate continuum and exhibits zero-energy periodic modes of instability. Finally, it is emphasized that the node-skipping force interactions, a salient feature of peridynamics, are physically unjustified (except on the atomic scale) because in reality the forces get transmitted to the second and farther neighboring particles (or nodes) through the displacements and rotations of the intermediate particles, rather than by some potential permeating particles as on the atomic scale.

Effect of Dispersant on Preparation of Barium Strontium Titanate Nanopowders by Microwave Hydrothermal Processing

Through the microwave-hydrothermal processing at 70 °C in 10 min, barium strontium titanate (BST) nanopowders are prepared by using butyl-titanate, barium nitrate and strontium nitrate as raw materials. Two kinds of dispersants namely polyethylene glycol 6000 and OP-10 are added, respectively. The dispersant mechanism and dosage on the crystal phase and microstructure are studied by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM). The results show that the dispersive effect of OP-10 is better than the polyethylene glycol 6000. The long chain of OP-10 can be used to disperse nanopowders through a space steric hindrance mechanism, well-dispersed BST nanopowders are obtained when mass percent ratio of dispersant (OP-10) is 5%.

An improved electrophoretic deposition method for wafer level white pc-LED array packaging

Combining the blue light-emitting diodes (LEDs) with the yellow phosphors, as called phosphors-converted white light-emitting diodes (pc-WLEDs), is an approach widely used for white LEDs manufacturing. The investigation of an improved electrophoretic deposition (EPD) method of conformal phosphor coating for pc-WLEDs packaging is presented in this paper. The antimony tin oxide (ATO) nanoparticles were used to coat surface of LED chips array to achieve an evenly distributed transparent conductive layer as electrode (i.e., cathode for EPD process) by the spray technique. A kind of dispersant was added into the suspension of prepared phosphor particles to improve the stability. The experimental measurement reveals that a sort of compact uniform distribution of the phosphor layer surrounding the LED chips' surface was realized with this newly developed EPD method. And the standard deviation of correlated color temperature (CCT) and luminous efficiency are 256.03 K and 3.06 lm/W, respectively. The prototype of phosphor coating on a multchip array scale demonstrates that a Wafer Level Chip Scale Packaging (WLCSP) for white pc-LEDs can be achieved with the improved EPD method in this work.

Dispersion Characterization of Short Slag Fiber in Aqueous Solution

Slag fiber with desirable properties is a promising candidate for applications as fillers or reinforced materials. Its poor dispersion in bulk materials, however, becomes the major challenge. Some aspects of its physicochemical properties were focused upon in the present article. The effect of three kinds of dispersants, viz., sodium carboxymethyl cellulose (CMC), anionic polyacrylamide (APAM), and cationic polyacrylamide (CPAM), as well as their combinations on the dispersion of slag fiber in aqueous solution was investigated. The viscosities of fiber suspensions were measured and the results were correlated with the dispersion of suspensions. It was shown that the slag fiber appeared amorphous, smooth surface with high length/diameter (L/d) ratio and negatively charged in water. The dispersion of slag fiber in aqueous solution directly depended on the dispersants. The optimal uniform and stable fiber suspension could be achieved under the dispersant concentration of the combination of 2 wt% CMC and 0.25 wt% APAM. In this case, the fiber concentration was as large as 25 g/L. In addition, the plausible dispersion mechanism of slag fiber in aqueous solutions was elucidated based on the electrostatic steric stabilization.

Microstructure and properties of nanostructured YSZ coating prepared by suspension plasma spraying at low pressure

Suspension plasma spraying as a new processing method was employed to deposit nanostructured YSZ coating at a low pressure down to 100Pa. A nanostructured YSZ powder, a kind of dispersant and ethanol were mixed uniformly prior to conducting the experiment. The axial injection mode was adopted to improve the enthalpy exchange between the plasma jet and sprayed material. The relatively dense coatings were obtained due to the higher velocity of particles accelerated by the relatively higher velocity of the plasma jet at low pressure. The optical emission spectroscopy was used to characterize the nature of the plasma jet and the sprayed YSZ material. The existence of vapor phase of YSZ was demonstrated. The phase and microstructure of the coating were characterized by XRD and SEM, respectively. It is revealed that the crystallite size of as-sprayed coating is reduced from 30nm for the feedstock to about 20nm after the thermal spraying process at low pressure. It is also found that the mean value of elastic moduli shows a decreasing tendency from 114.5 to 87.5GPa with the increase of spraying distance from 150 to 250mm, whereas the hardness shows a mean value up to 5.77GPa at a stand-off distance of 200mm. The hardness and the elastic moduli increase by 61% and 31% in comparison with the obtained values by SPS at atmospheric ambient by previous authors, respectively.

Dispersant affects the cellular influences of single-wall carbon nanotube: the role of CNT as carrier of dispersants

The application of carbon nanotube (CNT) as a functional material to engineering and life sciences is advanced. In order to evaluate the cytotoxicity of CNT in vitro, some chemical and biological reagents are used for dispersants. In the present study, the cellular influences of six kinds of chemical or biological reagents used as dispersants were examined. Pluronic F-127, Pluronic F-68, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), pulmonary surfactant preparation Surfacten®, bovine serum albumin (BSA) and Tween 80 were used in the preparation of CNT-medium dispersants. The influences of each reagent on cell viability in human lung carcinoma A549 cells were small. However, Pluronic F-127, DPPC, Surfacten® and Tween 80 induced an increase of intracellular reactive oxygen species (ROS) level. Next, CNT-medium dispersions were prepared, using each reagent as a dispersant and applied to A549 cells. The cellular influences depended on the kind of dispersant. Cells exposed to CNT dispersion including Pluronic® F-127, Surfacten®, DPPC and Tween 80 showed LDH release to the culture supernatant. Induction of intracellular ROS level was observed in cells exposed to CNT dispersion including each reagent except BSA. These results suggest that the adsorbed dispersant reagents on the surface of the CNT affect its cellular influences, particularly the induction of oxidative stress.

Research on the Adherence of the Water-based Ink

In order to improve the adhesion of water-based ink on substrate with low surface tension. Prepare ink samples of different dispersions with different kinds of dispersants and pigment/resin ratios and test their dispersion. Then prepare different ink samples with all kinds of film-forming resins and additives, measure the surface tension of the ink samples on the plastic which is used to characterize their wettability. Meanwhile use the IGT F1 printing eligibility instrument to make proofs with ink samples above. Discuss main factors that influence adhesion of water-based ink by analyzing wettability of ink samples. Research results indicate that: dispersion of water-based ink and resin have great influences on the adhesion on substrates with low surface tension; Right amount of adhesion promoter can effectively enhance the adhesion; The well wettability of ink on the substrates is the precondition to ensure adherence of the water-based ink.

Preparation and Properties of PEDOT/PSS Conductive Polymer Blended with Graphene/PVDF

Graphene has unique structure and excellent performance , It has good optical, thermal, mechanical properties and electrical conductivity. In this article , based on elaborating the structure , characteristic and preparation methods of the graphene , the modification of graphene in polymer composite was discussed and the development and research direction of the graphene/polymer composite were proposed. The conductivity of poly (3,4-ethylenedioxythiophene) (PEDOT) doped with poly(4-styrenesulfonate) (PSS) blended with different ratios of graphene/PVDF (polyvinylidiene fluoride) solution was measured. After dryness, we found that an addition of graphene/PVDF solution lowered the resistance by three or four orders of magnitude when the concentration are 25wt% and 50wt% , among them the Gb50 has the best surface conductivity, the magnitude is about 1.43 S/cm, and then we found that the second onset degradation temperature of PEDOT/PSS membrane blended with graphene/PVDF was 75°C higher than that of without blended with graphene/PVDF. All kind of dispersion has been studied using a four-point probe conductive meter, X-ray diffractometry (XRD), fourier transform infrared (FTIR), thermogravimetric analysis(TGA) and scanning electrical microscopy (SEM) in order to discuss the surface resistance, the crystallinity, the chemical structure , the thermal properties and morphology of the PEDOT/PSS-graphene/PVDF film. Conductive PEDOT/PSS-graphene/PVDF membrane has good electrical properties and thermal stability , which can be used for the electrolyte of lithium battery.

Influence of pH Value and Dispersants on the Alumina Suspension Stability

Alumina microparticles were synthesized by sol-gel method with aluminum isopropoxide as raw material, octanol and acetonitrile as solvent. The influence of pH value and three kinds of dispersants on the alumina suspension stability were discussed in water system. We find that The optimal pH value range of application for alumina suspension is 4-5 or 10-11, which has the biggest absolute value of Zeta potential, and alumina suspension has a good dispersion when Span-20 used as dispersant.

The Influence of Dispersant on the Forming Process of Alumina Ceramic

The influence of two kinds of dispersants PMAA-NH4 and PMAA-Na on the stability, rheology, solid volume content, green body strength, green body microstructure and dielectric property of the alumina ceramic slurry was studied. It is shown that two kinds of dispersants can reduce the particle agglomeration of ceramic slurry, which makes particle dispersion more uniform to produce high-performance alumina ceramic.

Crystallisation of nanohybrids of poly(ϵ-caprolactone) and hydrotalcites containing antimicrobial species

New composites of poly(ϵ-caprolactone) containing Zn/Al hydrotalcites [layer double hydroxide (LDH)] and ‘active’ antimicrobial anions (benzoate, dichlorobenzoate, o-hydroxybenzoate and p-hydroxybenzoate) prepared with two different techniques have been characterised through differential scanning calorimetry and dynamic mechanical analysis. The method of preparation of the samples has a strong influence on the dispersion of the nanolayers within the polymeric matrix, and, in turn, on the crystallisation kinetics: in fact, the samples prepared by high energy ball milling crystallise much faster than those prepared by casting. The different ‘active’ anions strongly affect the value of the LDH interlamellar distance, which, in turn, affects their capacity of dispersion in the polymer. As a consequence of the different kinds of dispersion, the sample containing benzoate LDH or dichlorobenzoate LDH crystallises faster than that containing p-hydroxybenzoate LDH. Such results are of great importance in the definition of processing and use conditions of such materials of potential interest in food ‘active’ packaging.