scholarly journals Fundamentals of beach volleyball blocking actions

2021 ◽  
Vol 15 (2) ◽  
pp. 90-100
Author(s):  
Gabriel Alexandru PETROVICI ◽  
◽  
Sorin ȘIMON ◽  

Beach volleyball is spectacular with many rapid actions, agility moves, and high jumping. One of the key elements present in high-performance beach volleyball, having a decisive role in the defensive apparatus, is the blocking movements. This action is done mainly by the tallest player or with the most considerable jumping ability. A high blocking ability can facilitate the defensive movement of the player that is positioned in the back of the court. Blocking ability is facilitated by anticipation capacity, good sight, agility movement, and high jumping ability generated by solid legs. This paper analyses the fundamentals of blocking actions in beach volleyball, giving critical elements in executing a good and efficient block.

2015 ◽  
Vol 73 (4) ◽  
Author(s):  
W. N. Aifa ◽  
M.R. Hainin ◽  
M.Z. Abd.Majid ◽  
R. MohamadZin ◽  
H. Yaacob ◽  
...  

A technology that has been experienced during the construction of a pavement has indicated the improvement in exploring the advanced technology pavement. Types of technologies of pavements applied are always related to the high performance of the pavements during the life span. Indeed, the application of technology in pavement has insisted to reduce the rate of environmental problems such as global warming, abundance of solid waste and so on. The development of technologies in pavement has been identified by the expert in highway engineering as one of the initiatives in response the sustainability requirement that later on will be applied to implement green highway concepts. Nowadays, the process of selecting a variety of green pavement technology element is becoming more challenging to be evaluated qualitatively. This paper aims to determine critical pavement technology element based on ranking of priority to achieve the objective of the green highway design. It is necessary to determine the critical elements in order to identify which elements will most contribute to the green practices based on the priority level of the weighted factor value. Therefore, a questionnaire survey was developed and distributed to the respondent in order to obtain the agreement level for the element. Based on the weighted analysis, it has been shown that the soil erosion control element has achieved first ranking in order to implement green highway and followed by permeable and cool pavement.In conclusion, the identification of critical elementsof green pavement technology is the main key towards sustainable development in the future.


2019 ◽  
Vol 14 (42) ◽  
pp. 289-295

The aim of the study was to show the differences in the game statistics related to the service in professional and junior category in three surfaces and to determine statistical differences during the game regarding both categories. A total of 269 individual Grand Slam tennis matches (Australian Open, Wimbledon and Roland Garros) were selected on three different surfaces (hard court, grass and clay). The data was collected from the official websites of the tournaments. A total of 10 variables were analyzed in professional category and 7 in junior. Absolute players obtained higher values (p <0.05) of aces, aces per set, percentage of 1st Services and points won with 1st and 2nd Service and committed fewer double faults per set than juniors in all surfaces. It is concluded that the increase in performance in the variables related to the service plays a decisive role in order to achieve a professional status.


Author(s):  
Khadidja Saidi ◽  
Mountassar Maamoun ◽  
M’hamed Bounekhla

The optimization of energy in a photovoltaic conversion chain remains a topic of study. The maximum power point tracking (MPPT) is considered the most appropriate solution to ensure the extraction of the maximum power which a photovoltaic generator can provide. Perturb and observe (P&amp;O) algorithm is the well-known MPPT tracker; it shows an important and decisive role in the development of photovoltaic (PV) systems. In This article we introduce a new improved adjustable step size P&amp;O (imVS_PO) MPPT method.The performances of the new algorithm are compared to the conventional P&amp;O MPPT techniques and to the existing adjustable step size P&amp;O (VS_PO) MPPT algorithm. The results clearly show the efficiency of the improved algorithm which contributed to the increase of the tracking speed with negligible fluctuations when the MPP is reached, and especially in rapid variation of insolation.


2005 ◽  
pp. 3-10
Author(s):  
Sándor Mihók

The utilisation of the horse has changed from time to time in response to human needs. For a few decades, it has been serving in several equestrian sports more intensively. It has also been proved that the standards for this kind of performance cannot be established in the way certain characteristics, such as the weight gain or milk production of other animal breeds can. Breeding horses for sporting comprises highly complex selection criteria.Some of these (e.g. external features, temperament, manageability and intelligence) do not put the breeder in a difficult position, but finding the traits that establishes the safety of sporting achievements poses a genetic problem.The performance of a horse for sports is a highly complex feature, which cannot easily be assessed or put down in figures. In addition, man plays a decisive role in shaping all kinds of performance of a horse at any given time by not only creating conditions for a better performance, but also by playing an active role in increasing it.The performance of the horse is mostly defined by its general aptitude to movement, ie., the regularity, clear rhythm and springiness of basic types of strides, as well as the ability to move in a naturally balanced way. Training and riding principles are based on these traits. These two together will determine about 70% of the value of the horse and its adequacy for high performance equestrian sports. In order to avoid subjectivity in determining the above variables and to increase the degree of objectivity, competent expert teams (trainers, judges, other riders) are employed to form an opinion on an individual animal.Assessing horse performance outside races does not seem to be efficient, as owing to the dominant effects of the environment, the indicator of inheritability is hardly above 0.1.Free jumping is an especially appropriate means for assessing a horse’s readiness and ability to move in an environment free of disturbing factors. In free jumping, it is especially important to judge the style of the jump. The first phase of jumping – as a sequence of movements – lasts from the moment the fore-feet touch the ground until the moment the hind-feet push off, while the second phase lasts from this moment until touching the ground. The most important task in the first phase is to make the angle of the dip of the body by the supporting fore-feet that is necessary for the jump. The quality of the jump is determined by the jumping and adequately expanded hind-legs. The intensity of pushing off and jumping done by the hind-legs can be inferred, and differences between individuals can be discerned from the shaping of the curve by the hocks and the paths of the pasterns in relation to the withers.


2020 ◽  
Vol 209 ◽  
pp. 06004
Author(s):  
Aleksey Edelev ◽  
Alexander Feoktistov ◽  
Igor Bychkov ◽  
Olga Basharina

This article presents a package for analyzing the energy system vulnerability developed with new technology for continuous integration, delivery, and deployment of applied software. It implements a framework that allows combining and optimally using various methods for modelling energy systems and provides the comprehensive assessment of their vulnerability with regard to various uncertainties. The essential principles to identify and rank critical elements of an energy system are considered in the article. The investigations made with the package shown that the principles seem to be logical for the subsequent construction of the invariant set of measures for improving the energy system resilience.


2016 ◽  
Vol 668 ◽  
pp. 80-86 ◽  
Author(s):  
Arjun K. Pathak ◽  
K.A. Gschneidner ◽  
M. Khan ◽  
R.W. McCallum ◽  
V.K. Pecharsky

1990 ◽  
Vol 200 ◽  
Author(s):  
M.H. Francombe ◽  
S.V. Krisknaswamy

ABSTRACTThin films of ferroelectric and piezoelectric materials are playing a growing role as critical elements in microwave acoustic devices, infrared imagers, integrated optic circuits, optical displays and high-performance semiconductor memories. In this review, we discuss recent progress in the control of growth, structure and properties of the main candidate materials, such as piezoelectric ZnO and AlN, and ferroelectric PZT-based solid solutions, KNbO3, bismuth titanate (Bi4Ti3O12), LiNbO3, LiTaO3 and KNO3. Brief mention is also made of the role and status ferroelectric polymers and of the BaMF4 class of fluorides. The emphasis of the review is primarily on vacuum-processed films, and optimization of characteristics required for integration into solid-state or semiconductor components.


2019 ◽  
Vol 12 (1) ◽  
pp. 451-473 ◽  
Author(s):  
Yu Liang ◽  
Lihua Zhang ◽  
Yukui Zhang

Chromatographic separation has been widely applied in various fields, such as chemical engineering, precision medicine, energy, and biology. Because chromatographic separation is based on differential partitioning between the mobile phase and stationary phase and affected by band dispersion and mass transfer resistance from these two phases, the materials used as the stationary phase play a decisive role in separation performance. In this review, we discuss the design of separation materials to achieve the separation with high efficiency and high resolution and highlight the well-defined materials with uniform pore structure and unique properties. The achievements, recent developments, challenges, and future trends of such materials are discussed. Furthermore, the surface functionalization of separation ma-terials for further improvement of separation performance is reviewed. Finally, future research directions and the challenges of chromatographic separation are presented.


2021 ◽  
Author(s):  
Urbi Pal ◽  
Dmitrii Rakov ◽  
Bingyu Lu ◽  
Baharak Sayahpour ◽  
Fangfang Chen ◽  
...  

<p>Future rechargeable Li metal batteries (LMBs) require a rational electrolyte design to stabilize</p><p>the interfaces between the electrolyte and both the lithium metal anode and the high voltage</p><p>cathode. This remains the greatest challenge in achieving high cycling performance in</p><p>LMBs. We report an ether-aided ionic liquid electrolyte which offers superior Li metal</p><p>deposition, high voltage (5 V) stability and non-flammability. High performance cycling of</p><p>LiNi0.8Mn0.1Co0.1O2 (4.4 V) and LiNi0.6Mn0.2Co0.2O2 (4.3 V) cells is demonstrated with high</p><p>coulombic efficiency (>99.5%) at room temperature and elevated temperatures, even at high</p><p>practical areal capacity for the latter of 3.8 mAh/cm2 and with a capacity retention of 91% after</p><p>100 cycles. The ether-ionic liquid chemistry enables desirable plated Li microstructures with</p><p>high packing density, minimal ‘dead’ or inactive lithium formation and dendrite-free long-term</p><p>cycling. Along with XPS studies of cycled electrode surfaces, we use molecular dynamics</p><p>simulations to demonstrate that changes to the electrolyte interfacial chemistry upon addition</p><p>of DME plays a decisive role in the formation of a compact stable SEI.</p>


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