Striking Accuracy Research Articles

Vulnerability analysis of power grid with the network science approach based on actual grid characteristics: A case study in Iran

The vulnerability analysis of power grids has long been of paramount interest to researchers and authorities. Network vulnerability analysis refers to beforehand evaluation of the impact of local failures on the network as a whole so that proper measures could be adopted before occurrence of any major crisis. Previous studies on power grid vulnerabilities that are based on network science concept have been mostly concentrated on topological measures and unweighted networks. In this paper, grid vulnerability identification is carried out by combined use of grid network topology and centrality measures along with real and physical characteristics of power grid. Namely line load and failure rate, with the help of Weighted PageRank algorithm. The main advantage of this approach is that it eliminates complex and time-consuming differential calculations, which results in reduced computation time, and allows real-time updating of the result based on changes in the actual grid characteristics. The proposed model was validated by implementation over a section of Iranian 400 kV and 230 kV power grids. The striking accuracy of the achieved result was confirmed by comparison against results that obtained through calculations by Iran’s national dispatching body.

Expedited Screening of Active and Regioselective Catalysts for the Hydroformylation Reaction

The discovery of new homogeneous catalysts that preferentially form one product over another in regio‐ or enantioselective chemical reactions has traditionally been the province of experimental chemists. Today, computational‐based approaches have carved an increasingly important role, which, for computational catalytic designs, often rely on highly inefficient combinatorial‐based screening methods. To increase the pace of discovery, tools capable of rapidly assessing large numbers of prospective species and identify those possessing desirable properties, such as activity and selectivity, are vital. Here, through the examination of the hydroformylation of 2‐methylpropene, we demonstrate how a new tool built upon molecular volcano plots can be used to quickly predict the activity of molecular catalysts as well as estimate the intrinsic ability of each species to form one regioisomer over the other with striking accuracy. Following training and validation, these regioselective molecular volcanoes are employed to predict catalysts that preferentially form the branched product (2,2‐dimethylpropanal) in violation of Keulemans’ 70‐year‐old law. Eighteen species (out of a total of 68 predicted) were computationally predicted to have regiomeric excess (r.e.) values > 90. Overall, these tools can be used to quickly screen the activity and selectivity of potential catalysis based on two easily computed descriptor variables.

Model characteristics of physical development, physical and technical preparedness of football players 15 years of different roles

The purpose of the work is to develop model characteristics of physical development, physical and technical preparedness of players of 15 years of different playing roles. Material and methods. Participants. In the study, 47 football players took part in 15 years of the Sports School "Areal" in Kharkov. Methods. Analysis of scientific and methodological literature, determination of physical development indicators testing of physical and technical preparedness, methods of mathematical statistics. The course of the study. The results of physical development, physical and technical preparedness of football players for 15 years are fixed. Model characteristics of physical and technical preparedness of young football players are developed. Analyzed comparative characteristics of the physical and technical preparedness of players 15 years of different playing roles. Results. It is established, according to the indicators of the physical development of players, players of different playing roles practically do not differ from each other. It is shown that the goalkeepers have practically the lowest technical and physical readiness indicators practically in all test results, in contrast to the attackers, defenders and midfielders. It is recommended that the development of a program for the development of physical qualities for goalkeepers, as well as the development of a separate program for improving the technical preparedness for players of each playing role. Conclusions. It is fixed, significant differences in the level of physical and technical preparedness between field players and goalkeepers. It is established that the greatest differences between representatives of different playing roles in terms of juggling, holding the ball on the foot, accuracy and range of strikes. It was revealed, not the reliability of the difference between the indicators of physical and technical preparedness of attackers, defenders and midfielders, which indicates their universality, and, therefore, possible replacement of each other.

Making Sense of the Initial Home visit: The Role of Intuition in Child and Family Social Workers’ Assessments of Risk

This article conceptualises the role of intuition in professional judgement. It draws on findings from an empirical study of home visiting in child and family social work. The study used a psychosocial analysis of narrative interviews (n = 18) to investigate how workers constructed a professional judgement in relation to an initial home visit. In contrast to deliberative or analytic reasoning, intuition is defined as a non-conscious mode of reasoning, allowing the individual to reach a rapid judgement about a situation or person, often with striking accuracy. In this study, CFSWs’ intuitions during their first encounter with the family were an important source of information for their assessment of risk – their emotional responses, ‘niggles’ and ‘gut feelings’ sensitised them to potentially salient information before it was rationally accessible. The study identifies five patterns used by Child and Family Social Workers (CFSWs) to assess risk during the initial encounter with parents: openness, coherence, emotional congruence, child focus and personal responsibility. It is argued that intuition is a product of experience, and is an important part of CFSWs’ decision-making toolkit. However, when accepted uncritically, intuitive reasoning can represent a risk for professional judgement through the creation of bias. The article identifies specific biases relevant to judgements made on the basis of an initial visit.

Effects of water velocity and substrate composition on foraging efficiency of an endangered benthic cyprinid, Nooksack dace (Rhinichthys cataractae subsp. cataractae)

To identify the mechanisms whereby substrate embeddedness and water velocity influence Nooksack dace (Rhinichthys cataractae subsp. cataractae) prey capture efficiency, we stocked dace in foraging arenas with varying substrate types over a range of velocities (0, 25, 35 cm s−1) and measured their efficiency of prey capture. We stocked a known number of mayfly (Ephemeroptera), black fly (Simuliidae), and chironomid (Chironomidae) larvae in each foraging arena and measured the number of invertebrates remaining after 12 h. Foraging efficiency for mayflies was significantly reduced over unembedded substrate, and capture efficiency for all taxa decreased at higher velocities in all substrate treatments. Decreased foraging efficiency indicates that higher velocities may degrade the accuracy of prey strikes, that dace may alter their foraging behavior to reduce energy expenditures at higher velocities, that there is less available foraging habitat within their velocity tolerances, or that invertebrates become more interstitial at higher velocities. Although it is difficult to unambiguously discriminate among these mechanisms with our experimental design, our results suggest that dace are adapted to foraging in low-velocity micro-habitats within the boundary layer, and that their foraging efficiency may be sensitive to both the refuging ability of their prey and velocity and turbulence at their focal point.

Direct evaluation of stress intensity factors for curved cracks using Irwin's integral and XFEM with high‐order enrichment functions

SummaryThis paper presents a comprehensive study on the use of Irwin's crack closure integral for direct evaluation of mixed‐mode stress intensity factors (SIFs) in curved crack problems, within the extended finite element method. The approach employs high‐order enrichment functions derived from the standard Williams asymptotic solution, and SIFs are computed in closed form without any special post‐processing requirements. Linear triangular elements are used to discretize the domain, and the crack curvature within an element is represented explicitly. An improved quadrature scheme using high‐order isoparametric mapping together with a generalized Duffy transformation is proposed to integrate singular fields in tip elements with curved cracks. Furthermore, because the Williams asymptotic solution is derived for straight cracks, an appropriate definition of the angle in the enrichment functions is presented and discussed. This contribution is an important extension of our previous work on straight cracks and illustrates the applicability of the SIF extraction method to curved cracks.The performance of the method is studied on several circular and parabolic arc crack benchmark examples. With two layers of elements enriched in the vicinity of the crack tip, striking accuracy, even on relatively coarse meshes, is obtained, and the method converges to the reference SIFs for the circular arc crack problem with mesh refinement. Furthermore, while the popular interaction integral (a variant of the J‐integral method) requires special auxiliary fields for curved cracks and also needs cracks to be sufficiently apart from each other in multicracks systems, the proposed approach shows none of those limitations. Copyright © 2017 John Wiley & Sons, Ltd.

Rattlesnakes are extremely fast and variable when striking at kangaroo rats in nature: Three-dimensional high-speed kinematics at night

Predation plays a central role in the lives of most organisms. Predators must find and subdue prey to survive and reproduce, whereas prey must avoid predators to do the same. The resultant antagonistic coevolution often leads to extreme adaptations in both parties. Few examples capture the imagination like a rapid strike from a venomous snake. However, almost nothing is known about strike performance of viperid snakes under natural conditions. We obtained high-speed (500 fps) three-dimensional video in the field (at night using infrared lights) of Mohave rattlesnakes (Crotalus scutulatus) attempting to capture Merriam’s kangaroo rats (Dipodomys merriami). Strikes occurred from a range of distances (4.6 to 20.6 cm), and rattlesnake performance was highly variable. Missed capture attempts resulted from both rapid escape maneuvers and poor strike accuracy. Maximum velocity and acceleration of some rattlesnake strikes fell within the range of reported laboratory values, but some far exceeded most observations. Thus, quantifying rapid predator-prey interactions in the wild will propel our understanding of animal performance.

Losing Ground?

This article offers a study of the Hackney Flashers' project Who's Holding the Baby? (1976–1978). The agitprop series documented the establishment of an independent nursery in North London, while providing analysis of the profoundly gendered and classed nature of such work. This historical example illustrates with striking accuracy transformations to the urban landscape of London over the past four decades, in particular pointing towards the critical entanglement between collective art practice, liberal voluntarism and processes of gentrification. The article therefore raises a set of problems: To what extent does feminised social reproduction labour and care voluntarism assuage or challenge the normative functioning of urban public space? What is the relationship of cultural to economic capital, and how is gender relevant to these forms of value? Has the potential of creative, urban protest tactics been exhausted? Drawing from writings across cultural geography and art history, the article proposes that a historical consideration of the Hackney Flashers opens up a pressing discussion around shifts in the organisation of social reproduction since the 1970s.

From play to proficiency: The ontogeny of stone-tool use in coastal-foraging long-tailed macaques (Macaca fascicularis) from a comparative perception-action perspective.

Macaques crack shellfish in coastal environments with specialized stone-hammering techniques. I provide the first examination of skill development from 866 object-manipulation and 7,400 tool-use bouts, collected over 15 months, using longitudinal analyses of infants' object manipulation (N = 7) and cross-sectional comparisons of manipulative and tool-use behavior (N = 69). I adopt a Perception-action approach, examining how the emergence of actions on objects relate to the spatial-relational and percussive challenges of tool use. Infants begin manipulating single items, particularly stones, at 1-2 months. Combining objects predominates (78%) by 1.5-2.5 years, and bouts involving food and tools but with incorrect spatial relations and action sequences prevail (73%) by 2.5-3.5 years. Placing, precedes rubbing objects on surfaces. Percussion emerges last, as disorganized striking before becoming consistent and targeted. Macaques manipulate combinations of stones and oysters, before stones, anvils, and motile shellfish, but success on either food type is only observed at 2.5-3.5 years. After competence, success rates and strike accuracy improve within 3 months on oysters and 5 months on motile shellfish. Older tool users (>4.5 years) had higher success rates, strike accuracy, strike efficiency, and tool fidelity. Macaque tool-use appears facilitated by a propensity for stone manipulation, but challenged by mastering spatial relations and percussion. I relate my findings to the development of stone-tool use in capuchins and chimpanzees, stone-handling in related macaque species, object play in Old World monkeys, and percussion in children, to further understand how biological propensities, environments, and social influences contribute to perception-action learning across species. (PsycINFO Database Record

Necessity of capillary modes in a minimal model of nanoscale hydrophobic solvation

Modern theories of the hydrophobic effect highlight its dependence on length scale, emphasizing the importance of interfaces in the vicinity of sizable hydrophobes. We recently showed that a faithful treatment of such nanoscale interfaces requires careful attention to the statistics of capillary waves, with significant quantitative implications for the calculation of solvation thermodynamics. Here, we show that a coarse-grained lattice model like that of Chandler [Chandler D (2005)Nature437(7059):640-647], when informed by this understanding, can capture a broad range of hydrophobic behaviors with striking accuracy. Specifically, we calculate probability distributions for microscopic density fluctuations that agree very well with results of atomistic simulations, even many SDs from the mean and even for probe volumes in highly heterogeneous environments. This accuracy is achieved without adjustment of free parameters, because the model is fully specified by well-known properties of liquid water. As examples of its utility, we compute the free-energy profile for a solute crossing the air-water interface, as well as the thermodynamic cost of evacuating the space between extended nanoscale surfaces. These calculations suggest that a highly reduced model for aqueous solvation can enable efficient multiscale modeling of spatial organization driven by hydrophobic and interfacial forces.

Adaptive delamination analysis

Summary A methodology aimed at addressing computational complexity of analyzing delamination in large structural components made of laminated composites is proposed. The classical ply-by-ply discretization of individual layers may increase the size of the problem by an order of magnitude in comparison with the laminated shell or plate element meshes. The paper features delamination indicators that pinpoint the onset and propagation of delamination fronts with striking accuracy. Once the location of delamination has been identified, the discrete solution space of the classical laminated plate/shell element is hierarchically enriched by a combination of weak and strong discontinuities to adaptively track the evolution of delamination fronts. The so-called adaptive s-method proposed herein is equivalent in terms of approximation space to the extended finite element method but offers sparser matrices and added flexibility in transitioning from weak to strong discontinuities. Numerical examples suggest that despite an overhead that comes with adaptivity, the adaptive s-method is computationally advantageous over the classical ply-by-ply discretization, especially as the problem size increases. Copyright © 2015 John Wiley & Sons, Ltd.

A Relativistic Newtonian Mechanics Predicts with Precision the Results of Recent Neutrino-Velocity Experiments

The research on quasi-luminal neutrinos has sparked several experimental studies for testing the "speed of light limit" hypothesis. Until today, the overall evidence favors the "null" hypothesis, stating that there is no significant difference between the observed velocities of light and neutrinos. Despite numerous theoretical models proposed to explain the neutrinos behavior, no attempt has been undertaken to predict the experimentally produced results. This paper presents a simple novel extension of Newton's mechanics to the domain of relativistic velocities. For a typical neutrino-velocity experiment, the proposed model is utilized to derive a general expression for . Comparison of the model's prediction with results of six neutrino-velocity experiments, conducted by five collaborations, reveals that the model predicts all the reported results with striking accuracy. Because in the proposed model, the direction of the neutrino flight matters, the model's impressive success in accounting for all the tested data, indicates a complete collapse of the Lorentz symmetry principle in situation involving quasi-luminal particles, moving in two opposite directions. This conclusion is support by previous findings, showing that an identical Sagnac effect to the one documented for radial motion, occurs also in linear motion.

Differentiation between Excellent and First-Grade Players According to a Number of Skilful Variables and Body Measurements in Volleyball

The research aims at : - Determining the most important skilful variables and body measurements for volleyball players ( 1st and excellent grades ) . - Obtaining separately both functions of skilful differentiation and body measurements for volleyball players ( 1st and excellent grades ) . The researchers have adopted the descriptive methodology with a survey style for its convenience to the nature of the research. The research community consists of the volleyball players . The sample has been selected randomly. It includes (29) volleyball players ( excellence Grade ) belonging to (Erbil sport club, Akad Einkawa club, and Shaklawah club ) and (48) 1st grade volleyball players belonging to ( Qaraqoush sport club, Ashourjah sport club , Suolav Al-Jadeed sport club, and Neshtiman sport club) . Thus, the total number becomes (77) players. A number of skilful tests have been applied ,like : the upper serve test , test of reception accuracy from serving , overhand passing test from rear area ,test of diametrical and linear smashing striking accuracy , screen test , and the test of defense skill accuracy from centre (6).On the other hand , the used body measurements are ( body weight , total body length , body length with hands up , arm length with the hand length , leg length , shoulders width , chest width, brachium circumference and thigh circumference ). The results have been processed by using SPSS. So, the researchers have concluded the following results: - Obtaining the equation of differentiation for the skilful variables and extracting three variables ( smashing striking , serve reception , and defending the field ) which have the ability to differentiate the volleyball players ( the excellent and the first grades ). - Obtaining the equation of differentiation for body measurements and extracting three measurements (shoulders width, total body length, and brachium circumference) which have the ability to differentiate the volleyball players ( the excellent and the first grades ). - Using the skilful variables and body measurements resulted from the research as an initial style in selecting the volleyball players ( 1st and excellent grades ) . - The need to pay attention to the skilful variables and body measurements, which have the ability to differentiate the volleyball players to be a base and support for the volleyball coaches. - Taking into account the following differentiating factors in volleyball when selecting and training players in addition to develop all the values as much as possible. The factors are : the skill accuracy of diametrical and linear smashing striketing , measuring reception accuracy from serving , defending the field , shoulders width , total body length and brachium circumference . - Making studies on other morphological and functional variables that effect on players level in volleyball.

Martial arts striking hand peak acceleration, accuracy and consistency

The goal of this paper was to investigate the possible trade-off between peak hand acceleration and accuracy and consistency of hand strikes performed by martial artists of different training experiences. Ten male martial artists with training experience ranging from one to nine years volunteered to participate in the experiment. Each participant performed 12 maximum effort goal-directed strikes. Hand acceleration during the strikes was obtained using a tri-axial accelerometer block. A pressure sensor matrix was used to determine the accuracy and consistency of the strikes. Accuracy was estimated by the radial distance between the centroid of each subject's 12 strikes and the target, whereas consistency was estimated by the square root of the 12 strikes mean squared distance from their centroid. We found that training experience was significantly correlated to hand peak acceleration prior to impact (r2=0.456, p =0.032) and accuracy (r2=0. 621, p=0.012). These correlations suggest that more experienced participants exhibited higher hand peak accelerations and at the same time were more accurate. Training experience, however, was not correlated to consistency (r2=0.085, p=0.413). Overall, our results suggest that martial arts training may lead practitioners to achieve higher striking hand accelerations with better accuracy and no change in striking consistency.

Fusion of locomotor maneuvers, and improving sensory capabilities, give rise to the flexible homing strikes of juvenile zebrafish

At 5 days post-fertilization and 4 mm in length, zebrafish larvae are successful predators of mobile prey items. The tracking and capture of 200 μm long Paramecia requires efficient sensorimotor transformations and precise neural controls that activate axial musculature for orientation and propulsion, while coordinating jaw muscle activity to engulf them. Using high-speed imaging, we report striking changes across ontogeny in the kinematics, structure and efficacy of zebrafish feeding episodes. Most notably, the discrete tracking maneuvers used by larval fish (turns, forward swims) become fused with prey capture swims to form the continuous, fluid homing strikes of juvenile and adult zebrafish. Across this same developmental time frame, the duration of feeding episodes become much shorter, with strikes occurring at broader angles and from much greater distances than seen with larval zebrafish. Moreover, juveniles use a surprisingly diverse array of motor patterns that constitute a flexible predatory strategy. This enhances the ability of zebrafish to capture more mobile prey items such as Artemia. Visually-guided tracking is complemented by the mechanosensory lateral line system. Neomycin ablation of lateral line hair cells reduced the accuracy of strikes and overall feeding rates, especially when neomycin-treated larvae and juveniles were placed in the dark. Darkness by itself reduced the distance from which strikes were launched, as visualized by infrared imaging. Rapid growth and changing morphology, including ossification of skeletal elements and differentiation of control musculature, present challenges for sustaining and enhancing predatory capabilities. The concurrent expansion of the cerebellum and subpallium (an ancestral basal ganglia) may contribute to the emergence of juvenile homing strikes, whose ontogeny possibly mirrors a phylogenetic expansion of motor capabilities.

Activity of shoulder muscles during shots of different difficulty level in more and less skilled novus players

The aim of the present study was to compare the activation of the shoulder muscles in more and less skilled novus players during shots of different difficulty level. Nineteen competitive novus players (9 more skilled and 10 less skilled) were recruited to examine bioelectrical activity of the shoulder muscles (trapezius, deltoid lateral and posterior muscles) during a striking accuracy task. Participants performed 3 series, each consisted of 10 novus shots – 10 penalties, 10 cut and 10 rebound shots. Surface EMG (sEMG) amplitude of posterior and lateral deltoid and trapezius muscle of the subjects' dominant side was measured during the shot and compared between successful versus unsuccessful shots in more skilled and less skilled players. Unsuccessful penalties and rebound strokes compared to successful ones in more and less skilled players, and unsuccessful cut shots compared to successful ones in more skilled players are characterized by higher activity in trapezius muscle. Higher activity of trapezius muscle is a characteristic feature of less skilled players' novus shots. During successful penalties, cut and rebound shots the sEMG amplitude of trapezius muscle in more skilled players was significantly lower (34%; p<0.05; 19%; p<0.001 and 60%; p<0.01, respectively) than in less skilled players.

Unraveling the Combined Effects of Dielectric and Viscosity Profiles on Surface Capacitance, Electro-Osmotic Mobility, and Electric Surface Conductivity

We calculate the electro-osmotic mobility and surface conductivity at a solid-liquid interface from a modified Poisson-Boltzmann equation, including spatial variations of the dielectric function and the viscosity that where extracted previously from molecular dynamics simulations of aqueous interfaces. The low-dielectric region directly at the interface leads to a substantially reduced surface capacitance. At the same time, ions accumulate into a highly condensed interfacial layer, leading to the well-known saturation of the electro-osmotic mobility at large surface charge density regardless of the hydrodynamic boundary conditions. The experimentally well-established apparent excess surface conductivity follows from our model for all hydrodynamic boundary conditions without additional assumptions. Our theory fits multiple published sets of experimental data on hydrophilic and hydrophobic surfaces with striking accuracy, using the nonelectrostatic ion-surface interaction as the only fitting parameter.

Equilibrium Strategy and Population-Size Effects in Lowest Unique Bid Auctions

In lowest unique bid auctions, N players bid for an item. The winner is whoever places the lowest bid, provided that it is also unique. We use a grand canonical approach to derive an analytical expression for the equilibrium distribution of strategies. We then study the properties of the solution as a function of the mean number of players, and compare them with a large data set of internet auctions. The theory agrees with the data with striking accuracy for small population-size N, while for larger N a qualitatively different distribution is observed. We interpret this result as the emergence of two different regimes, one in which adaptation is feasible and one in which it is not. Our results question the actual possibility of a large population to adapt and find the optimal strategy when participating in a collective game.

The design of optimal guidance law with multi-constraints using block pulse functions

When there are time-varying parameters in motion equations, the optimal guidance law with multi-constraints generally cannot be solved analytically. Based on block pulse functions, a design method of optimal guidance law is presented combining optimal control theory and numerical value computation for time-varying systems. The presented guidance law can optimize the combination of landing angle, miss distance, and control energy consumption. Using both the proposed guidance law and the proportional navigation law, ballistic simulations are made. Compared to the proportional navigation law, the optimal guidance law is able to more than double the landing angle. Because of the steep terminal trajectory, the strike accuracy and damage effects are increased. Averaging the time-varying coefficients of the optimal guidance law, a suboptimal guidance law is obtained. This guidance law is simpler and can make the terminal trajectory steep too. Therefore, it could be applied to projects more easily and requires less onboard computational resources. However, it consumes slightly more control energy than the optimal guidance law.

VALUATION FUNCTIONALS AND STATIC NO ARBITRAGE OPTION PRICING FORMULAS

Often in practice, the implied volatility of an option is calculated to find the option price tomorrow or the prices of ‘nearby’ options. To show that one does not need to adhere to the Black- Scholes formula in this scheme, Figlewski has provided a new pricing formula and has shown that his ‘alternating passive model’ performs as well as the Black-Scholes formula [8]. The Figlewski model was modified by Henderson et al. so that the formula would have no static arbitrage [10]. In this paper, we show how to construct a huge class of such static no arbitrage pricing functions, making use of distortions, coherent risk measures and the pricing theory in incomplete markets by Carr et al. [4]. Through this construction, we provide a more elaborate static no arbitrage pricing formula than Black-Sholes in the above scheme. Moreover, using our pricing formula, we find a volatility curve which fits with striking accuracy the synthetic data used by Henderson et al. [10].