Aggregation Parameters Research Articles

Parameters of wheeled tractors and arable aggregates taking into account zonal conditions

The article considers the justification of the parameters of wheeled tractors and arable aggregates taking into account zonal conditions. The system of forming a promising size range of wheeled tractors and agricultural units for separate enterprises, agricultural zones and the whole country was based on scientifical principles of operational technologies of mechanized work that establish the basic levels and tasks of adapting energy resources to natural-production conditions. In developing models and an algorithm for optimizing operational parameters, the most objective indicators were applied, including the optimal net productivity of the arable aggregate for different classes of rut length and the tractor’s density. We established the optimal and maximum permissible in operation () values of the density of wheeled tractors for the set of production conditions, regardless by rut length according to the results of modeling and field tests. The rational mass and energy parameters of the tractors for each rut length class were justified, included in the size range of the proposed two-parameter classification system and the corresponding values for the width of the arable unit.

Structural analysis of income and risk dynamics in models of economic growth

The purpose of the research is to carry out the structural analysis of income and risk dynamics when considering the problem of economic growth, to obtain and apply the structural formula to assess the contribution of GDP elements to growth rate. The methodological basis of the research consists of the theory of economic growth and structural analysis, optimization methods and computer simulation (algorithmization) models of maximizing income and minimizing the total risk of N objects of the economic system. The implementation of the two stages of the research allowed us to establish that for the Russian economy the main contribution to the growth rate in the period 2003–2018 was made by gross consumption, but not by investment spending. The result of computer simulation of optimization models—maximizing income and minimizing risk is that the solution to the problem of structural choice can be an assessment of the dynamics of income and risk at a characteristic point in which different resource allocation structures give the same combination of income and risk. However, the growth rate of income and risk in the characteristic point will certainly be different, and the most acceptable option is to choose the structure that gives a positive growth rate of income and a negative growth rate of risk. This circumstance makes a significant addition to the developed macroeconomic and structural policy measures, which should be oriented not only to some static targets, but also to the impact on the dynamics of the relevant aggregated parameters—income and risk.

Delay and backlog control of aggregation systems for wireless communications

The aggregation system implemented in wireless communication networks aims to optimize the network efficiency regarding the encapsulation information and the medium access mechanisms. This paper proposes to evaluate the performances of such (A-MSDU like) system from a dedicated frame point of view, which is important in order to predict the Quality of Service offered to a client or to an application. Regarding the incoming flows, enabling or disabling the aggregation system, and tuning in real time the aggregate size, makes possible to satisfy both the users’ requirement and the network provider efficiency. In the case of voice or video class wireless communication where some loss of data is acceptable, numerous simulations using Riverbed Modeler led to express several recommendations embedded in an algorithm which sets dynamically the aggregation parameters in order to adjust it to the incoming traffic.

ESTUDIO PRELIMINAR DE LOS EFECTOS DE LAS RADIACIONES GAMMA SOBRE LOS GLÓBULOS ROJOS HUMANOS

In this study, the alterations in viscoelastic and aggregation parameters of red blood cells were analyzed for usual gamma irradiation procedures for transfusion purposes. In order to determine possible hemorheological changes that may affect the health of patients and their relationship with the biochemical changes observed, the blood samples were irradiated at different doses. The results show alterations in the erythrocyte aggregation time, in the membrane surface viscosity and in the size of the aggregates in the irradiated samples, suggesting that the damage produced by the ionizing radiation affects the physical properties of red blood cell membrane at different levels.

P1442 Outcomes of patients with left ventricular noncompaction and preserved ejection fraction

Abstract BACKGROUND Left ventricular noncompaction (LVNC) has a wide phenotypic expression. Prognosis of patients with preserved ejection fraction (pEF) remains uncertain. PURPOSE To describe the characteristics and natural history of this subgroup of patients. METHODS LVNC patients were included in a multicentric registry. Those with pEF (LVEF > 50%) were considered for the analysis. RESULTS 491 LVNC pts from 10 Spanish centres were recruited from 2000 to 2018. 239 (49%) had baseline pEF. Compared to those with reduced EF (rEF), they were younger, with no differences in gender and had less comorbilities (Table 1). Mean LVEF was 62% (SD 8). 18 pts (9% of the available CMR) had fibrosis even though LV volumes and LVEF were normal. Family screening was completed in 199 pts, being positive in 113 (57%). Genetic testing was performed in 146 index cases, being positive in 80 (55%): ACTC1 (40), MYH7 (17), TTN (8), HCN4 (6) and other individual variants. During a median follow-up of 4.9 years (IQR 2.1-7.3), there was a significant decrease in LVEF: last LVEF was 30- 40% in 5 pts (2%) and 40-50% in 21 (9%) (p = 0.01 compared to baseline LVEF). 6 pts (2.5%) died during follow-up, only 1 of cardiovascular cause. 9 patients (4%) presented heart failure (HF) and 25 (10.5%) ventricular tachycardia or fibrillation (VT/VF). All cardiovascular outcomes were less frequent compared to rEF (Image 1, all p < 0.05). In multivariate analysis (including demographic, imaging, genetic and family aggregation parameters) the only predictor for HF was change in LVEF (OR 0.89, mean LVEF at the event 47%, p = 0.01 compared to no HF). Fibrosis was not associated with VT/VF. CONCLUSIONS Patients with LVNC and pEF have an overall excellent prognosis, which is markedly better than those with rEF. However, there is progressive decrease in LVEF, associated with heart failure, and moderate risk of life threatening arrhythmias. Therefore, periodic follow-up should be promoted. Table 1 LVNC pEF (n = 239) LVNC rEF (n = 252) p Men, n (%) 131 (55) 146 (58) 0.65 Median age at diagnosis (IQR) - yr 38 (23-54) 58 (42-72) 0.01 Median follow up (IQR) - yr 4.9 (2.1-7.3) 3.9 (1.4-7.9) 0.04 QRS (SD) - ms 93 (18) 117 (32) 0.01 LGE, n (%) 18 (9) 52 (30) 0.01 Abstract P1442 Figure. Image 1

Numerical simulation of the erythrocyte aggregation process in an experiment with micropipettes

The Finite Element Method is proposed as a method to model the erythrocyte aggregation process. This paper presents the results of the simulation of an experiment in which hydraulic micropipettes were used to form a pair of erythrocyte aggregates in a dextran 150 kDa medium. The parameters of erythrocyte aggregation (the value of the attracting pressure normal to the surface of erythrocytes, size of the contact zone, and erythrocyte membrane strain energy) were determined by comparing the results obtained experimentally and performing the numerical simulation. The mathematical modeling of the erythrocyte aggregation process was performed taking into account shear stresses. The shear stress values were obtained using the Couette model and compared with the results of experiments on the separation of paired aggregates of erythrocytes.

CТРУКТУРНЫЕ ПАРАМЕТРЫ ВОДНЫХ КОЛЛОИДНЫХ ДИСПЕРСИЙ ФУЛЛЕРЕНА C60

Two types of fullerene C60 water dispersions were investigated by a small-angle X-ray and neutron scattering. As a result, structural parameters of fullerene aggregates were obtained. The water dispersions were obtained by the solvent-exchange technique and by huge dilution of initial C60/Nmethylpyrrolidone solution. The structure organization of water dispersions is considered in respect to their technique preparation. It was shown that fullerene aggregates were characterized by highly polydispersity in size for all dispersions. In the case of son/nC60 dispersion it was found that fullerenes formed aggregates with a dense nucleus (namely a surface fractal) with a radius of 58 ± 1 nm and a fractal dimension of 2.3. In turn, the nmp/nC60 system was characterized by the branched aggregates with fractal dimension 1.5 and bimodal particle size distribution.

The Assessment of Effectiveness of R&D within the Framework of Federal Target Programs

The purpose of this study is to develop approaches to assessing the effectiveness of R&D of civilian use carried out within the framework of federal target programs based on integrated accounting of performance indicators and the cost of projects. Methods of comparative analysis as well as the methods of expert estimations were used. The developed methodology is tested on the example of the most knowledge-intensive program — the Federal Targeted Program “Research and development on priority directions of scientific and technological complex of Russia for 2014-2020” showing its practical applicability. It confirmed the hypothesis about the existence of significant differentiation of projects containing R&D according to the quantitative structure as well as scientific and technical potential of the established objects of intellectual property in comparison with the costs of R&D. The existing system for assessing the effectiveness of R&D conducted within the framework of targeted programs is carried out with aggregate output parameters and does not pay attention to the specific contribution of each project in improving the indicators of the entire program. The authors proposed to use the concepts of “weighted effectiveness” and “innovative efficiency” of projects. The quantitative evaluation of projects based on these parameters made it possible for us to perform the ranking of projects, to identify groups of projects with varying degrees of innovative efficiency, and to distribute the most effective, low efficiency and expensive projects according to thematic areas of research.

Optimization of the flocculation process of industrial waste water treatment

The influence of the concentration of the solid phase and the flow rate of the flocculant on the change in the sedimentation rate of the solid phase and the strength of the floccules is studied. A technique is proposed for optimizing the parameters of aggregation and increasing the strength of floccules after hydromechanical influences, taking into account the concentration of the solid phase and the flocculant flow. It is found that the optimal conditions for aggregation can be achieved by minimizing the hydromechanical effects on floccules, as well as creating the best conditions for flocculation. Among the ways to optimize the process, the ways of influencing these factors due to the technological features of the introduction of the process are analyzed, such as concentration adjustment, transport rate of flocculed sludge, mixing time

Experimental evaluation of the permanent strains of open-graded aggregate materials

In permeable pavement systems, open-graded aggregates are commonly used for base and subbase layers that allow water to store and drain. At each traffic load cycle, the permanent strain accumulates and is considered to be one of major distresses in permeable pavement systems. This study investigates the permanent strain of open-graded aggregate material using the multi-stage repeated-load triaxial test. For this purpose, the open-graded aggregate materials with three different gradations, from a single quarry, were used. Their nominal maximum aggregate sizes were 13, 25, and 40 mm. In the multi-stage repeated-load triaxial test, the specimen is subjected to five loading sequences and each sequence is comprised of six stress combinations. At each stress combination, the specimen is subjected to 10,000 load repetitions. Based on the test results, the material parameters of the predictive model were determined and then used to predict the permanent strains of three open-graded aggregates in other loading sequences. The test results and the predictions showed that specimen whose gradation bounded by two others happened to have the highest resistance to permanent strain. Regardless of the difference in aggregate sizes, the material parameters of the open-graded aggregates did not vary significantly. In addition, open-graded aggregate materials were more dependent on bulk stress than deviator stress.

Land subsidence risk assessment using GIS fuzzy logic spatial modeling in Varamin aquifer, Iran

The extent of the subsidence and the consequents damage to most of the residential and populated areas of Iran have made this phenomenon one of the most important natural hazards after the earthquake. Accordingly, in this research to assess the land subsidence risk, a GIS fuzzy logic spatial modeling was applied. In this regard, four stages were performed. In stage 1, 14 factors affecting subsidence including aquifer thickness, bedrock depth, Debi zonation of pumping wells, transmissivity, specific yield, Groundwater drawdown in 20 year, soil type, slope, altitude based on DEM, erosion, annual rainfall, distance of fault, lithological units, and land use, were prepared based on the literature review. In stage 2, the parameters were standardized with the fuzzy membership functions. Moreover, in stage 3, for aggregation parameters, several fuzzy overlay operation models were used. Finally, to verification of the models, the statistical benchmarks based on observed land subsidence were used. Accordingly, the “GAMMA 0.8” fuzzy overlay model with the most abundance of rank 1, and the “SUM” fuzzy overlay model with the most abundance of rank 16 among the other models are introduced as the most consistent and the worst consistent models with observed land subsidence data, respectively.

Removal of Azo dyes with Xanthan

The interaction among Xanthan (XANT) and three azo dyes: Direct blue 1 (DB1), Direct red 81 (DR81), and Direct black 22 (DB22) was studied. The Xanthan-dye-Al product was formed after the addition of AlCl3 to a Xanthan-Dye adduct containing solution. It was proposed that polyhydroxyoxoaluminum clusters named CAL-13 and CAL-30 react with this adduct producing a Xanthanate aluminum network, XANT-Al, and as a consequence a decrease in dye concentration in an aqueous medium was observed. The removal efficiencies obtained were the following: DB1 (99 %), DB22 (99 %) and DR81 (94 %), demonstrating that this dye removal method is very efficient. The Zimm-Bragg model adequately described the experimental data and the order observed in the Ku (nucleation) and U (aggregation) parameters from this model was the following: DB1>DB22> DR81. Evidence suggests that physicochemical properties of dyes such as charge, molecular weight, aggregation ability and the capacity of XANT-Al to trap dye molecules are involved in the high removal values. Moreover, the dye binding mechanisms include: electrostatic, hydrogen bonding and hydrophobic interactions that determine the magnitude of the parameters Ku and U. These findings suggest that the XANT polymer is a good option to remove azo dyes from an aqueous medium.

Influence of gradation on asphalt mix rutting resistance measured by Hamburg Wheel Tracking test

Aggregate gradation is a key characteristic affecting the asphalt mix rutting resistance. The relationship between mix gradation and rutting behavior has been comprehensively studied, but only a few studies have incorporated the testing results from the Hamburg Wheel Tracking (HWT) test. This study used HWT test results to discuss the influence of four mix design variables, namely asphalt binder content, 4.75 mm key sieve passing, coarse particle gradation variation (>4.75 mm) and fine particles gradation variation (<4.75 mm) on the mix rutting resistance. A total of 26 asphalt mixes were tested using HWT test at 50 °C. Fine Aggregate (FAc) parameter derived from Bailey method was applied to quantitatively describe the gradation characteristic and was correlated with the creep slope from HWT tests. The results showed that both excessive and inadequate asphalt binder contents will impair the rutting performance. Increasing the mix 4.75 mm passing ratio from 20% to 35% slowly increases the rutting depth, with the passing ratio exceeding 41%, the mix exhibits significantly reduced rutting resistance and stripping behavior is observed. Mix skeleton with a uniform gradation in each size shows the minimum rutting resistance because smaller particles could damage the integrity of the mix skeleton by pushing the coarse aggregate open. Skeleton composed by 13.2–9.5 mm aggregates outperforms the skeleton composed by 9.5–4.75 mm aggregates. A finer gradation in aggregate fine fraction (<4.75 mm) has a positive influence on the rutting resistance as the HWT creep slope negatively correlates with the mix FAC parameter (R2 = 0.73).

FEATURES OF USING STATISTICAL METHODS IN INVESTIGATIONS OF THE BLACK SEA SANDY COAST MACROINVERTEBRATES

Relevance. The feature of the sandy beaches as the marginal biotope complex is that most of the environmental gradients act across the coastline. The low amplitude of the tides and the non-periodic wind tides determine the dynamics and specificity of these zones in the north-western Black Sea (NWBS). Because of this, the macroinvertebrate sampling design in the NWBS and the statistical processing of the results need special attention.Aim. The purpose of this paper is to review the methods of statistical data processing that will allow us to clarify and extend our understanding of the structure of macro-invertebrate sand beach communities of NWBS and the features of their use.Main results. The shape of the sampling device slightly affects the catch of macrofauna. It is acceptable to use both transects and randomized stratified sampling.A reliable estimation of quantity is provided by kriging methods and recalculation of density per length of the coastline.The coefficient b of the Taylor equation and the regression of mean crowding characterize species-specific aggregation. For estimation of distribution it is recommended to use spatial autocorrelation coefficients (Moran's I, Geary’s C), Ripley’s K function, JCA (for binary data) and SADIE.The relationship between the spatial distributions of species from one sampling station can be detected by the Mantel test.The biological diversity of macroinvertebrates of NWBS sandy beaches is relatively low, so unspecific fauna can significantly affect the value of indices.Influence of environmental factors on macroinvertebrates, their groups and communities can be measured using regression analysis or more specific methods.Suggestions. It is recommended to use a randomized stratified sampling design. Species-specific aggregation parameters should be evaluated by density-independent indices. Geostatistical methods are recommended for estimating the spatial distribution. It is suggested to estimate the number by the results, interpolated by kriging methods. For calculation of biodiversity, it is recommended to exclude randomly introduced species from the sample. It is recommended to use logistic, multiple linear regression and Mantel test to evaluate the impact of environmental factors. The analysis should evaluate the effect of factors at different time scales and use beach indices to characterize beaches.

Physicochemical determinants in stabilizing soil aggregates along a hydrological stress gradient on reservoir riparian habitats: Implications to soil restoration

Stability of soil aggregates, playing a significant role in soil quality, has been greatly impacted by wetting-drying cycles. Yet, determinants in stabilizing soil aggregate structure have been rarely clarified under the hydrological stress. Therefore, under the hydrological stress, this study evaluated the relative importance of soil physicochemical properties in stabilizing soil aggregates on the water level fluctuating zones of the Three Gorges Reservoir riparian at China's Yangtze River. Water stable aggregates of soils (large macroaggregates: > 2 mm, small macroaggregates: 0.25–2 mm, microaggregates: 0.053–0.25 mm, silt- and clay-sized aggregates: 0–0.053 mm) were measured by wet sieving, and soil aggregate stability was evaluated as mean weight diameter (MWD), geometric mean diameter (GMD) and fractal dimension (D) of soil aggregate and soil erodibility parameter (K). Physicochemical properties of the riparian soils were analyzed as total carbon, nitrogen, organic matter, phosphorus and potassium content, C/N ratio, soil mechanical composition, pH, bulk density and moisture content. The results indicated that soil total carbon, nitrogen, organic matter, phosphorus and potassium were highly concentrated in the areas under strong hydrological stress; the pH was mainly alkalinity, pH value and bulk density both decreased along the incremental stress gradient. The findings revealed that the proportion and stability of water stable aggregates were affected by hydrological stress, and stability indices were interpreted by pH, C/N ratio, potassium and silt contents. Aggregates showed the highest and lowest stability under intermediate and strong stress, respectively, however, no significant difference was found between weak and none stress. Finally, our results suggested that the riparian ecosystem may have the ability of autogenic restoration for soil stability. Under intermediate hydrological stress level, autogenic restoration with less human intervention would be recommended for stabilizing the riparian soil. However, under strong hydrological stress, anthropogenic restoration is still needed to stabilize soil structure and reduce soil erosion in the reservoir riparian habitats.

Analysis of the flocculation process of fine tailings particles in saltwater through a population balance model

A population balance model is used to describe the flocculation of tailings particles in aqueous salt solutions. The synthetic tailings, composed of quartz and kaolin particles, are flocculated in a jar at a constant shear rate where in-situ FBRM determines the size of the aggregates. The model follows the dynamics of aggregation and breakage processes and provides a good approximation to the temporal evolution of aggregate size. The fractal and permeable nature of the aggregates are considered, while the depletion of the collision efficiency allows describing the initial growth of aggregates and subsequent size reduction. The numerical solution requires five parameters, which are obtained by minimizing the difference between experimental size data and model predictions. A specific aim is to study the effect of magnesium hydroxide that is formed at pH ca. 10, and its interaction with flocculant, on the flocculation kinetics parameters. At pH ≥ 10 the aggregates grow less due to the presence of the magnesium hydroxide gel that surrounds quartz, kaolin and flocculant. The fractal dimension is quite stable at pH < 10 with a representative value of 2.7, typical of a clustered network, although in the presence of magnesium at pH ≥ 10 the fractal dimension of the aggregates is only 2.2, typical of Gaussian chains. Tailings aggregates in the presence of hydroxide are smaller and weakly three-dimensional and therefore contribute little to the settling velocity. The aggregation and breakage parameters are largely constant for a particulate system which composition remains unchanged over a pH range, and if the composition changes, for example by precipitation of magnesium hydroxide, then the aggregation parameters are different but close to constant.

Application of the steady-state and unsteady-state lasers in reconstructing the geometrical characteristic parameters of soot fractal aggregates

The unsteady-state laser, i.e. time-domain (TD) and frequency-domain (FD) lasers, and the steady-state (SS) laser are employed as the measurement lasers to reconstruct the geometrical characteristic parameters of soot fractal aggregates, i.e. the root mean square radius Rg and fractal dimension Df. The direct problems are solved by the finite volume method and Rayleigh-Debye-Gans fractal aggregate method, while an improved artificial bee colony algorithm is used as the inverse problem algorithm. The sensitivity analysis is employed to study the effective sampling region of the TD and FD laser measurement signals, and the results show that the time-resolved signals selected within [L, 0.5L + ctp] for the TD laser and the dimensionless frequency selected within [0.5, 5] for the FD laser are conducive to improving the retrieval accuracy. Then, the geometrical characteristic parameters of soot fractal aggregates are retrieved by using different measurement lasers, and the results reveal that the retrieval accuracy can be ensured by using the TD laser measurement technique. Moreover, the retrieval accuracy and robustness of Rg are better than those of Df. All the studies in the present manuscript supply an application plat of the laser measurement techniques in reconstructing the geometrical characteristic parameters of soot fractal aggregates.

Formation of the properties of the structure of disperse-filled polymer composites

The influence of the structure on the properties of the metal-polymer composite consisting of a polymer matrix in the form of epoxy resin (ED-20) with butadiene-styrene rubber (BSK), dispersedly filled with copper nanoparticles, is investigated. In the framework of fractal analysis, the real diameter of the aggregates of the initial filler particles was calculated for various concentrations and size of the filling particles and for different compositions of the polymer matrix. The concept of the structure of a polymer composite as a combination of two fractals (multifractals) was substantially used, which allows to determine the principles of the polymer matrix plasticity changes and to reveal the main factors affecting the degree of perturbation of its structure. Using fractal analysis methods, the influence of factors on the fractal dimension of the surface of initial filler particles aggregates and on the pattern of its dependence both on the degree of aggregation and on the fractal dimension of the frame of the particle aggregate is investigated The proposed approach enables prediction the fi nal parameters of aggregates of nanoparticles as a function of the size of the initial particles, their concentration and chemical properties of the surface of the polymer matrix.

The independent characterization and experimental study of coarse aggregate angularity

The morphological parameters of coarse aggregates, including the angularity, flat and elongated (FE) and particle size, strongly influence the performance of asphalt concrete. At present, the measurement of the angularity of coarse aggregate is affected by the particle size and the FE. To achieve independent characterization of angularity, the compression method is used to eliminate the influence of FE on angularity. In this paper, the angularity index (AI) is calculated by fitting ellipse method, which can eliminate the influence of aggregate particle size on the angularity of coarse aggregate. The research results show that the independent characterization of the angularity of coarse aggregates can improve the measurement accuracy of the angularity of coarse aggregates.

An optimized evaluation strategy for a comprehensive morphological soot nanoparticle aggregate characterization by electron microscopy

For a comprehensive understanding of nanoparticle formation in gas phase processes, such as soot formation, morphological parameters of fractal-like particle aggregates, like the radius of gyration, the fractal dimension and the primary particle size, have to be determined. Often transmission electron microscopy (TEM) is employed for the investigation of particle characteristics as it not only allows to investigate ensemble averages but single particle aggregates and thus also to determine statistical properties, such as the size distribution within a sample. Many different evaluation methods can be found in the literature. We investigated different approaches for the determination of morphological parameters from TEM images of soot and compared the results to derive an optimized evaluation strategy for TEM nanoparticle characterization. We compared four methods for the determination of the radius of gyration – three length- and one pixel-based methods – showing good agreement within 9% deviation for the median of the recovered lognormal size distribution. Furthermore, the fractal dimension was determined via a sample-based and various box counting methods with different limiting box sizes. Here, we could show that the upper and lower bounds (aggregate size in terms of radius of gyration and primary particle size in terms of its radius, respectively) of self-similarity of fractal-like aggregates should be accounted for by choosing corresponding upper and lower box sizes. Using box counting, we could show that for small aggregates the fractal dimension as well as its span are increased, yet with increasing aggregate size the fractal dimension converges towards 1.6. Furthermore, we could show the potential of semi-automatic aggregate detection through Trainable Weka Segmentation. However, image noise resulting in erroneous aggregate splitting often leads to smaller aggregate sizes by automatic detection compared to manual segmentation. Generalized Hough Transformation for the semi-automatic determination of primary particle sizes performs well for large soot particle aggregates as those often show spherical primary particles. For leaner combustion conditions, the primary particles of the formed clumpy soot aggregates cannot be detected well via semi-automatic detection. TEM images were taken on soot samples from premixed laminar flat flames (burner type: McKenna) under various conditions to provide comprehensive reference data.