The effect of different playing surfaces on soccer skill performance

Football (soccer) is traditionally played on natural grass but artificial surfaces are becoming an increasing popular alternative. Understanding how different surfaces affect a player's skill performance has not been examined. This study sought to compare soccer skill performance, using a validated test, on natural grass, third generation (3G) artificial turf, and indoor sprung wooden floor. Following familiarisation, 14 male players (12.7 ± 0.5 years-old, with 6.21 years playing experience) performed the Loughborough Soccer Passing Test (LSPT) on three different surfaces in the following order: indoor, grass and artificial turf. Players were given two practise attempts before the best of two trials were recorded. Movement time was faster on artificial turf (45.1 ± 1.3 s) than natural grass (46.2 ± 1.8 s; p = 0.045), but there was no difference in overall LSPT performance between grass (54.1 ± 4.2 s) and artificial turf (54.0 ± 4.7 s; p = 0.92). Overall LSPT performance was better on indoor surface (50.9 ± 4.6 s) than grass (p = 0.02) and artificial turf (p = 0.02) due to reduced penalty time on the indoor surface (5.5 ± 3.3 s) than grass (7.9 ± 2.9 s; p = 0.001) and artificial turf (8.9 ± 3.9 s; p = 0.003). There is no difference in soccer skill performance between grass and 3G artificial turf. Skill performance on an indoor surface was ∼6% better than both grass and 3G artificial turf due to better ball control and/or accuracy of passing. Our findings will enable comparison of studies using the LSPT on indoor and outdoor (grass or artificial) surfaces.

The duration of export trade relations and its influential factors in China's wooden floor

PurposeThis article will select 25 years of subdivided data to perform Kaplan–Meier survival analysis on the export trade relations of Chinese wooden flooring, use discrete-time cloglog models to analyze influencing factors, use logit and probit models to test the robustness, and try to systematically reveal the duration of China's wood flooring export trade and its influencing factors.Design/methodology/approachThis study used Kaplan–Meier survival function estimation method. In the survival analysis, survival function and hazard rate function are often used to characterize the distribution of survival time.FindingsThe continuous average export time of China's wooden flooring is relatively long, about 14 years. China's wooden flooring has a negative time dependency. After the export trade exceeds the threshold value of 15 years, the failure rate of trade greatly decreases, which has a “threshold effect.” Gravity model variables have a significant impact on the duration of China's wooden floor export.Originality/valueStudying the duration of forest products trade is of great significance for clearing deep-level trade relations and promoting sustainable development of forest products trade.

Research on dynamic characteristics test of wooden floor structure for gymnasium

In order to better evaluate the structural performance of the wooden floor used in the gymnasium and realize the structural optimization design, this research considered two gymnasium’s floors in Nanjing as the research object and used the transient excitation method to test the natural frequency and damping ratio parameters of the three types of floor structures. The results showed that three kinds of floor structures all meet the requirements of building comfort; under the premise that the types and specifications of the constituent materials were the same, the order of the damping ratios of the three kinds of floor structures from large to small was: the fixed floor structure with double-layer load distribution strip, the suspended floor structure with single-layer load distribution strip, and the suspended floor structure with double-layer load distribution strip; compared with the fixed floor structure, the suspended floor structure had low damping ratio characteristics, the energy dissipation was slow during structural vibration, which means its impact absorption rate was small, and its impact buffering ability was good. The integral structure had good resilience performance; compared with the floor structure using single-layer load distribution strip. The floor structure using a double-layer load distribution strip had a low damping ratio characteristic. The absorption rate of the structure was small and the resilience performance was good. The research conclusion had certain engineering application value.

Defect Index of Timberwork in House, Korea

Wood is a material that is familiar to humans and environment-friendly, and it is used widely as a building material. However, as the dispute over housing defects have increased in Korea, various defects have occurred in timberwork and have become disputes. Notwithstanding, efforts to analyze defects in timberwork systematically to reasonably solve the problem are lacking. In this study, defects in timberwork from housing complexes in Korea were standardized, and critical defects were selected to suggest a method as a management standard. The standard for defects includes time, types of facility work, location and subject, and defect phenomenon. The defect time is categorized into before handover and after handover, whereas facility work is divided into woodwork, door and window work, finishing work, and miscellaneous work. Location and subject are categorized into 13 areas, such as ceiling, floor, and door, and phenomena concerned are of 14 types, including faults and no installation. Therefore, the standardized defect items according to such criteria are classified into a total of 63 types. Ten defect items, whose numbers of defect occurrences per defect and defect repair cost ratio above the average, were selected, including discoloration and breakage of the wooden floor. The repair cost ratio of these defect items accounted for 85.62% of the total repair costs. On the contrary, the repair cost for the defects from the timber work outlined in the Construction Appraisal Practice, a representative defect standard in Korea, was 54.54% of the total. Meanwhile, according to the Defect Judgment Standard, the defect repair cost attributed 45.54% of the total. Therefore, since the 10 defect items proposed in this study can explain the defects in the timberwork compared with other standards, it would be reasonable to designate these 10 defect items as essential defects.

Between Hemse and Mästermyr

The distance between Hemse church and the fields of Mästermyr on the Swedish Island of Gotland is about eight kilometers. The distance or rather the proximity between these two places is given importance in this filmed research article. In the 1930s, a farmer found a wooden chest in Mästermyr containing hundreds of forged tools and other artefacts. During a restoration of the Romanesque Hemse church in the 1890s, reused parts of a stave church were discovered in the wooden floor. The hypothetical question that is investigated in this study is whether the tools from Mästermyr were used in the construction of Hemse stave church in the early 1100’s? This filmed article analyzes and compares the traces of toolmarks in Hemse stave church and the woodworking tools from the Märstermyr finding. Through a forensic examination involving 3D scanning with structured light, 3D printing and reconstruction of tools and woodworking procedures, it is revealed that several toolmarks in the stave church correspond to the characteristics of woodworking tools in the Mästermyr find. The tool's shape, dimensions and mode of operation are traced in its negative imprint in the stave church’s oak wood.

Area of Irregular Shaped Roof

This project makes use of calculus, specifically integration, to find the exact area of a roof garden to minimize the cost of material used in flooring it. Since the roof is of irregular shape, it is divided into four sections, the integral of each section is taken, and a relationship between the integrals is generated. Positive results are found, and the data reveal that the area of the grass floor is 175.3 m2 while the area of the wooden floor is 23.4 m2 with the total price being 2472 US dollars.

Methods for determining mechanical properties of walls

Masonry buildings with wooden floor structures, not equipped with vertical and horizontal tie beams, suffered the greatest damage in the earthquake that hit Zagreb on 22 March 2020. It is very significant to know mechanical properties of walls during preparation of the masonry buildings renovation design and, consequently, methods for determining such properties are presented in detailed in this paper. In addition to description of these methods, results obtained by testing shear strength of walls of twenty masonry buildings in Zagreb (149 measuring points in total) are also presented, as well as the results obtained by testing compressive strength of bricks on 14 buildings, using a total of 62 samples.

From the herringbone dome by Sangallo to the Serlio floor of Emy (and beyond)

The research starts from an analogy found between two apparently very different structural solutions: the double spiral pattern of the herringbone brick courses in the domes built by Antonio da Sangallo the Younger (1484-1546) during the Renaissance, and the particular pattern of a wooden floor ‘à la Serlio’, described by Amand Rose Emy in his Treatise at the beginning of 19th century, made by diagonal beams reciprocally sustained. The diagonal pattern of the floor has a geometrical relationship with the cross-herringbone pattern, so that the latter can be obtained by some geometrical transformations of the former. This pattern was also used in thin shells built by Nervi, from the destroyed airplane hangars in Tuscany to the Palazzetto dello sport in Rome, and even by Piacentini in 1936 and earlier in some neoclassical domes. Thus the construction tool, useful for building domes without expensive scaffolding, could have a structural role at the completed construction stage. Within the research different structures were investigated, in order to observe the relevance of this peculiar structural scheme particularly in the construction of modern domes.