Force performance of trawl system – III: mathematical modeling (part I)

The force performance of trawl systems directly depends on the work performed by these forces.The mechanical work of a trawl system is a physical quantity that depends on the vectors of force (hydrodynamic, tension, compression, etc.) and displacement. Thermodynamic work is the amount of energy transmitted or received by the trawl system by changing its external parameters. There is also the work of the forces of the electrostatic field when the charge moves from one point of the field to another. Equations are obtained for ideal flexible steel ropes and rope-rope products, characterizing the direct proportionality of the ratio of the productivity of forces that are directed perpendicular to each other and depend on the Poisson's ratio and the constructive elongation of ideal flexible steel ropes and cordage products. The ratio of the capacities of the forces or the ratio of the moduli of elasticity in the transverse and longitudinal directions, which arise when steel ropes and rope-rope products are stretched, are inversely proportional to the square of the coefficient k connecting the elongation λ, Poisson's ratio μ and the relative elongation ε at a constant volume of the product and its mass. There has been described an example of stretching perfectly flexible steel ropes and cordage. Such constructive parameters as lay, the number of strands, wire and fiber thickness, type of weaving were not taken into account.

Insights into the reversal error from a study with South African and Spanish prospective primary teachers

This study, using a quantitative approach, examined Spanish and South African pre-service teachers’ responses to translating word problems based on direct proportionality into equations. The participants were 79 South African and 211 Spanish prospective primary school teachers who were in their second year of a Bachelor of Education degree. The study’s general objective was to compare the students’ proficiency in expressing direct proportionality word problems as equations, with a particular focus on the extent of the reversal error among the students’ responses. Furthermore, the study sought to test the explanatory power of word order matching and the static comparison as causes of the reversal error in the two contexts. The study found that South African students had a higher proportion of correct responses across all the items. While nearly all the errors made by Spanish students were reversals, the South African group barely committed reversal errors. However, a subgroup of the South African students made errors consisting of equations that do not make sense in the situation, suggesting that they had poor foundational knowledge of the multiplicative comparison relation and did not understand the functioning of the algebraic language. The study also found that the word order matching strategy has some explanatory power for the reversal error in both contexts. However, the static comparison strategy offers explanatory power only in the Spanish context, suggesting that there may be a difference in curriculum and instructional approaches in the middle and secondary years of schooling, which is when equations are taught.

Depths Inferred from Velocities Estimated by Remote Sensing: A Flow Resistance Equation-Based Approach to Mapping Multiple River Attributes at the Reach Scale

Remote sensing of flow conditions in stream channels could facilitate hydrologic data collection, particularly in large, inaccessible rivers. Previous research has demonstrated the potential to estimate flow velocities in sediment-laden rivers via particle image velocimetry (PIV). In this study, we introduce a new framework for also obtaining bathymetric information: Depths Inferred from Velocities Estimated by Remote Sensing (DIVERS). This approach is based on a flow resistance equation and involves several assumptions: steady, uniform, one-dimensional flow and a direct proportionality between the velocity estimated at a given location and the local water depth, with no lateral transfer of mass or momentum. As an initial case study, we performed PIV and inferred depths from videos acquired from a helicopter hovering at multiple waypoints along a large river in central Alaska. The accuracy of PIV-derived velocities was assessed via comparison to field measurements and the performance of an optimization-based approach to DIVERS specification of roughness

CALCULATION OF FUNDAMENTAL STRUCTURES BY THE METHOD OF DEFORMATIONS

The unceasing process of urbanization all over the world and the constantly growingcost of land plots allotted for development makes investors, scientists and engineers look for and findways to reduce the unit cost of construction of useful areas of buildings and structures for variouspurposes.The most effective way to reduce the unit cost of construction of useful areas of buildings andstructures is to increase their number of storeys and depths of underground parts. But with an increasein the height of buildings, the loads on their foundations also increase, stimulating scientists andengineers to search for more advanced methods and methods for solving problems related todetermining the rational parameters of the foundations of buildings and structures, improving thequality and reliability of the calculation methods used.The results obtained using modern methods of calculating foundations in some cases lead to anoverestimation of the costs of building materials, in some – to a decrease in comparison with the realstrength and deformation indicators of the foundations of construction objects.This book describes a deformation method that allows you to improve the calculations of thestress-strain state of pile and some other types of foundations by expressing the deformations offoundation structures by the dependence of the foundation settlement on the rigidity of the«foundation-foundation» system and the coefficient of foundation rigidity, which varies along thelength or depth of the foundations, which will significantly improve the performance of buildings andstructures.Based on the hypothesis of direct proportionality (Winkler), we use the ability of such a modelof the basis to take any variable stiffness along the length of the structure that transmits the load tothe ground. Representing a system of unconnected springs of different stiffness, such a base is able tomimic the resolution of the currently used different models within the base of the foundations. However, outside the sole, Winkler cannot consider the resolution of the real soil in terms ofinteraction with adjacent foundations. Thus, we are going to take into account only the «internal»resolution of different models of the basis. It is not difficult to obtain this information using analyticaland numerical methods for determining the stress-strain state of the soil base.

The boson peak and the first sharp diffraction peak in (As2S3)x(GeS2)1–x glasses

The parameters of the boson peak (BP) and the first sharp diffraction peak (FSDP) in (As2S3)x(GeS2)1x glasses measured using high-resolution Raman spectroscopy and high-energy synchrotron X-ray diffraction measurements are examined as a function of x. It has been found that there is no correlation between the positions of BP and FSDP. The BP position shows a nonlinear composition behavior with a maximum at about x = 0.4, whereas the FSDP position changes virtually linearly with x. The intensities of both BP and FSDP show nonlinear composition dependences with the slope changes at x = 0.4, although there is no direct proportionality. Analysis of the partial structure factors for the glasses with x = 0.2, 0.4 and 0.6 obtained in another study has shown that the cation-cation atomic pairs of Ge–Ge, Ge–As and As–As make the largest contribution to FSDP, where the Ge–Ge and Ge–As pairs are dominant.

Differentiating axonal loss and demyelination in chronic MS lesions: A novel approach using single streamline diffusivity analysis

We describe a new single-streamline based approach to analyse diffusivity within chronic MS lesions. We used the proposed method to examine diffusivity profiles in 30 patients with relapsing multiple sclerosis and observed a significant increase of both RD and AD within the lesion core (0.38+/-0.09 μm2/ms and 0.30+/-0.12 μm2/ms respectively, p<0.0001 for both) that gradually and symmetrically diminished away from the lesion. T1-hypointensity derived axonal loss correlated highly with ΔAD (r = 0.82, p<0.0001), but moderately with ΔRD (r = 0.60, p<0.0001). Furthermore, the trendline of the ΔAD vs axonal loss intersected both axes at zero indicating close agreement between two measures in assessing the degree of axonal loss. Conversely, the trendline of the ΔRD function demonstrated a high positive value at the zero level of axonal loss, suggesting that even lesions with preserved axonal content exhibit a significant increase of RD. There was also a significant negative correlation between the level of preferential RD increase (ΔRD-ΔAD) in the lesion core and the degree of axonal damage (r = -0.62, p<0.001), indicating that ΔRD dominates in cases with milder axonal loss. Modelling diffusivity changes in the core of chronic MS lesions based on the direct proportionality of ΔAD with axonal loss and the proposed dual nature of ΔRD yielded results that were strikingly similar to the experimental data. Evaluation of lesions in a sizable cohort of MS patients using the proposed method supports the use of ΔAD as a marker of axonal loss; and the notion that demyelination and axonal loss independently contribute to the increase of RD in chronic MS lesions. The work highlights the importance of selecting appropriate patient cohorts for clinical trials of pro-remyelinating and neuroprotective therapeutics.

Comprehensive quantification of fuel use by the failing and nonfailing human heart

The heart consumes circulating nutrients to fuel lifelong contraction, but a comprehensive mapping of human cardiac fuel use is lacking. We used metabolomics on blood from artery, coronary sinus, and femoral vein in 110 patients with or without heart failure to quantify the uptake and release of 277 metabolites, including all major nutrients, by the human heart and leg. The heart primarily consumed fatty acids and, unexpectedly, little glucose; secreted glutamine and other nitrogen-rich amino acids, indicating active protein breakdown, at a rate ~10 times that of the leg; and released intermediates of the tricarboxylic acid cycle, balancing anaplerosis from amino acid breakdown. Both heart and leg consumed ketones, glutamate, and acetate in direct proportionality to circulating levels, indicating that availability is a key driver for consumption of these substrates. The failing heart consumed more ketones and lactate and had higher rates of proteolysis. These data provide a comprehensive and quantitative picture of human cardiac fuel use.

Does the Darcy–Buckingham Law Apply to Flow through Unsaturated Porous Rock?

The Darcy–Buckingham (DB) law, critical to the prediction of unsaturated flow, is widely used but has rarely been experimentally tested, and therefore may not be adequate in certain conditions. Failure of this law would imply that the unsaturated hydraulic conductivity is not constant for a given water content, as assumed in nearly all subsurface flow models. This study aims to test the DB law on unsaturated porous rock, complementing the few previous tests, all done on soils. Two lithotypes of calcareous porous rocks were tested. The quasi-steady centrifuge method was used to measure the flux density for different centrifugal driving forces while maintaining essentially constant water content, as required. Any deviations from the direct proportionality of the measured flux and the applied force would indicate a violation of the DB law. Our results show that, for the tested rocks and conditions, no physical phenomena occurred to cause a failure of the DB law.

Effect of Life Expectancy on Technological Development

The manuscript looks into the improvement of Life Expectancy and the number of invention patents filed in USA over the last two centuries. The direct proportionality between Technological advancement and Life Expectancy proves that the two indices are co­related. However, the co­relation when viewed with the lag present between Life Expectancy and Technological advancement indicates that the Technological advancement depends on the Life Expectancy and not visa versa. This notionally proves increased Life expectancy as the cause to Technological developments being made in USA.

Examining Caregivers’ Independence in Early Intervention Home Visit Sessions

The purpose of this study was to examine how a delineated coaching process affected the ability of caregivers to take the lead in promoting their children’s learning in the context of daily activities. In addition, the correspondence between caregivers’ initiations during the intervention and their rate of improvement after the intervention was investigated. One provider coached three culturally diverse caregivers to use development-enhancing strategies with their children who evidenced moderate–severe disabilities. The coaching process designated by the acronym SOOPR, include targeted information sharing (S), observation and provision of opportunities for the caregiver to practice new skills with provider feedback (OO), problem solving and reflection (P), and review of the session (R). Results reveal that all three caregivers increased their initiations of three of four development-promoting behaviors: teaching, responsiveness, and encouragement. The descriptive data across sessions for each triad suggest that as the intervention progressed, the frequency of specific coaching strategies decreased which may have fostered the caregivers’ opportunities to take the lead in the sessions. In addition, a consistent pattern of direct proportionality between caregiver rate of improvement after the intervention and caregiver initiations during the intervention was identified. Study limitations and implications for research and practice are discussed.