Search

As train speeds increase, the aerodynamic effects generated during the passage of high-speed trains in tunnels become more pronounced. This article investigates the influence of line spacing on the aerodynamic forces during the passage of high-speed trains in tunnels at different speeds. The research methodology is based on the three-dimensional transient compressible Reynolds-averaged Navier-Stokes (RANS) equations and the k-ω Shear Stress Transport (SST) turbulence model, using overset grid technology to simulate the train passing process in the tunnel. The results show that the aerodynamic drag, lateral force, and lift experienced by the train increase as the line spacing decreases and as the speed increases. line spacing has the greatest impact on aerodynamic lift, followed by lateral force, with drag having the smallest impact. Compared to line spacing, speed has a much larger effect on aerodynamic forces. The aerodynamic forces experienced by the train during tunnel passage are proportional to the square of the train's speed and have an exponential relationship with the line spacing during train passage. [ABSTRACT FROM AUTHOR]

Recent interest in scaling commercial kelp industries in Western cultures is juxtaposed by the apparent challenges in achieving more consistent and predictable yields. As such, site-level factors are a dominant and recurring conversation amongst stakeholders. The availability of seawater nitrogen (nitrate, ammonium, total N) can be highly variable across space and time and is often one of the top concerns for site selection and permitting. This study questions the relative importance of nitrogen availability on the yield of Saccharina latissima (sugar kelp) across five commercial farms on the U.S. East and West Coasts over two seasons, highlighting the relative influence of other interacting factors (i.e., farm design). We hypothesized that nitrate would strongly correlate with the harvested yield. Our results show significant spatial and annual variability in the kelp yield and ambient nutrients across and within farms, but with weak covariance. Standard linear regression suggests that seawater nitrogen is a poor explanatory factor for kelp yield, explaining 11.0% of the variation around the mean compared to the line spacing (explaining 26.1%) and the interaction between the total N and the line spacing (explaining 50.0%). Quartile regression, however, suggests that total N alone, is the strongest predictor of a lower threshold in terms of the yield (0.10 quartile, r2 = 0.431) relative to the median (0.50 quartile, r2 0.081). As such, seawater nitrogen may be a more useful metric in predicting baseline kelp yields rather than realized yields, and production above that baseline is likely more dependent on other factors that may or may not interact with seawater nitrogen. [ABSTRACT FROM AUTHOR]

Copyright of Uranium Geology is the property of Uranium Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract As train speeds increase, the aerodynamic effects generated during the passage of high-speed trains in tunnels become more pronounced. This article investigates the influence of line spacing on the aerodynamic forces during the passage of high-speed trains in tunnels at different speeds. The research methodology is based on the three-dimensional transient compressible Reynolds-averaged Navier-Stokes (RANS) equations and the k-ω Shear Stress Transport (SST) turbulence model, using overset grid technology to simulate the train passing process in the tunnel. The results show that the aerodynamic drag, lateral force, and lift experienced by the train increase as the line spacing decreases and as the speed increases. line spacing has the greatest impact on aerodynamic lift, followed by lateral force, with drag having the smallest impact. Compared to line spacing, speed has a much larger effect on aerodynamic forces. The aerodynamic forces experienced by the train during tunnel passage are proportional to the square of the train’s speed and have an exponential relationship with the line spacing during train passage.

Recent interest in scaling commercial kelp industries in Western cultures is juxtaposed by the apparent challenges in achieving more consistent and predictable yields. As such, site-level factors are a dominant and recurring conversation amongst stakeholders. The availability of seawater nitrogen (nitrate, ammonium, total N) can be highly variable across space and time and is often one of the top concerns for site selection and permitting. This study questions the relative importance of nitrogen availability on the yield of Saccharina latissima (sugar kelp) across five commercial farms on the U.S. East and West Coasts over two seasons, highlighting the relative influence of other interacting factors (i.e., farm design). We hypothesized that nitrate would strongly correlate with the harvested yield. Our results show significant spatial and annual variability in the kelp yield and ambient nutrients across and within farms, but with weak covariance. Standard linear regression suggests that seawater nitrogen is a poor explanatory factor for kelp yield, explaining 11.0% of the variation around the mean compared to the line spacing (explaining 26.1%) and the interaction between the total N and the line spacing (explaining 50.0%). Quartile regression, however, suggests that total N alone, is the strongest predictor of a lower threshold in terms of the yield (0.10 quartile, r2 = 0.431) relative to the median (0.50 quartile, r2 0.081). As such, seawater nitrogen may be a more useful metric in predicting baseline kelp yields rather than realized yields, and production above that baseline is likely more dependent on other factors that may or may not interact with seawater nitrogen.

Copyright of Xinjiang Agricultural Sciences is the property of Xinjiang Agricultural Sciences Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Objective] The influences of barrier height (H), porosity (P), and row spacing (R) on the erosion protection of a vertical sunflower sand barrier were studied in order to provide a theoretical basis for optimizing the parameter configuration of a vertical sunflower stalk sand barrier and the development of a vertical sand barrier wind and sand control project. [Methods] Based on field observations of wind speed and sand transport, research on the variation characteristics of sand barrier roughness, windproof effect, and sand blocking effect under different parameter configurations was conducted. [Methods] ① The main windproof area of the sand barrier was 0—50 cm above the soil surface. Compared with the roughness of the bare dune sand barrier, the roughness was increased by 7.70—214.45 times, the windproof effect of each specification of sand barrier was in the range of 11.74%—59.45%, and the sand barrier effect was in the range of 33.06%—92.23%. ② The wind and sand barrier effect of the sand barrier increased with an increase in barrier height, and decreased with an increase in porosity and row spacing. The influence of barrier height on the wind protection effect was greater than the influence of porosity, and the influence of porosity on the sand barrier effect was greater than the influence of barrier height. ③ The windproof effect and sand barrier effect of H(30 cm)-P(40%)-R(2 m), H(30 cm)-P(50%)-R(1 m), H(40 cm)-P(40%)-R(2 m), H(40 cm)-P(50%)-R(2 m) reached 35% and 75%, respectively. [Conclusion] A vertical sunflower stalk sand barrier can effectively reduce wind speed and sand transport amount. Sand barrier parameters are the key to affecting the protective effect of a sand barrier. The most important parameters affecting the windproof effect and sand barrier effect of a sand barrier are barrier height and porosity.

Copyright of Bulletin of Soil & Water Conservation is the property of Bulletin of Soil & Water Conservation Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In regions where transmission corridors are badly needed, UHV lines will inevitably be constructed in parallel with other UHV or EHV lines. Hence, the electromagnetic environment characteristics near the corridors are complex and in-depth study should be carried out. In this paper, three models of parallel AC transmission lines are established, and the characteristics of the power frequency electromagnetic field, radio interference and audible noise near the parallel lines are studied. The results show that as the line spacing decreases, the area of strong electromagnetic environment reduces, but the amplitude will increase. The height of the parallel-erected line has more influence on the distribution of the power frequency electromagnetic field than the radio interference and audible noise. Generally, the electromagnetic environment generated by the parallel erection of UHV transmission lines is related to the conductor height and the spacing of parallel lines. When the radio interference and audible noise limits are up to standard, the spacing of parallel erection lines can be appropriately reduced. This study has a certain reference significance for the design and construction of UHV lines in areas being short of corridors.

The objective was to evaluate the agronomic characteristics and productivity of peanuts BRS 423 OL submitted to different spacing and populations in two consecutive harvests. The experiments were carried out in the agricultural years 2018/19 and 2019/20 in the experimental area of the Federal Institute of Education, Science and Technology of Mato Grosso -- Campus São Vicente, Campo Verde Reference Center, located in the municipality of Campo Verde -- MT. The experimental design used was in randomized blocks, with five replications, and the plots consisted of two lines three meters long, with an interval of two meters between plots. The cultivar used was BRS 423 OL, and the treatments were: 1 -- Population of 222,222 plants ha-1 in the spacing of 0.90 m between rows and 20 plants m-1, 2 -- Population of 222,222 plants ha-1 in the spacing 0.73 m x 0.17 m between double rows and 10 plants m-1, 3 -- Population of 285,714 plants ha-1 in the spacing of 0.70 m between rows and 20 plants m-1 and 4 -- Population of 214,285 plants ha-1 in the spacing of 0.70 m between rows and 15 plants m-1. In the field conditions in which this research was developed, it can be concluded that: Plant heights, dry weight per plant, number of branches per plant and number of grains per pod were not significantly influenced in the two agricultural years due to the different peanut spacing and population densities BRS 423 OL. In the 2019/20 agricultural year, pod yields differed statistically, with a population of 222,222 plants ha-1 under spacing of 0.73 m x 0.17 m and 10 plants m-1 and a plant population of 214,285 plants ha-1 under spacing. 0.70 m and 15 plants m-1 were the most productive. [ABSTRACT FROM AUTHOR]

[Introduction] Multi power transmission lines arranged in the same corridor could avoid the land division and reduce the adverse effect on the local planning and development, but the personal safety of operators in the process of towers and conductors erection of subsequent power lines should be seriously considered as a result of induced voltage of the previous energized transmission lines. [Method] One DC transmission line under construction was taken as an example, electrostatic induced voltage generated from multi UHVDC transmission lines nearby in the same corridor were studied and calculated. The influence factors including the operating mode of UHVDC lines, line spacing from the energized power lines and length of stringing conductors were analyzed at the same time. [Result] The results show that the induced voltage got significantly high from adjacent UHVDC lines, and operation mode of energized lines played an important part; the less line spacing reduce, the higher induced voltage reach; the steady-state current from ion current density generated by UHVDC lines flowing through construction equipments have nearly less impact to constructors. Induced voltage of the stringing conductors will be paid much attention to when stringing and conductors and equipments should be grounded effectively. [Conclusion] The research results also have guiding significance to power lines′ construction which be adjacent to live lines.

With declining vision ability, character spacing and size on smartphones designed for the general population are not accessible for older adults. This study aimed to explore how larger Chinese character spacing and size affect older adults' user experience (UX). An orthogonal experiment was conducted. The optimal range of font size (FS), word spacing (WS) and line spacing (LS) were proposed utilising subjective evaluations to investigate the correlation of eye movement data with participants perceived UX. The results showed that improvement in different aspects of UX varied when FS, WS and LS increased. Overall, participants preferred larger FS, WS and LS, however, the larger FS, WS and LS values are more likely to cause errors and slower reading speed. These results suggest that the distinct combination of size and spacing depends on the motivation, needs and situation of older people when reading on a smartphone. These findings will help designers to provide better design for the older people. [ABSTRACT FROM AUTHOR]

The transmission distance of DC project is always long, and along the transmission distance, the structure of lines and towers varies according to local environment. It is hard to build a precise harmonic model composed of different sections of line with exact line parameters, so it is important to research the influence of line structure on the harmonic distribution in system and find the key parameters, in order to simplify the model. By building models of different line parameters in harmonic analysis program and calculating, it is found that the line spacing has a strong influence, the influence of height weakens when higher, the earth resistivity, ground wires and conductor type affect little, but the bundle number and spacing affect a lot, especially at low frequency. The influence rules on filter equipment are the same. The EMTPC simulation verified these conclusions. Combined with the practical project design convention, the height is the most important subsection basis. It is verified that a simplified model of a few line sections of different parameters can simulate the harmonics in project exactly.

This paper presents a thermo-mechanical finite element analysis model for the stress and fatigue analyses of engine pistons. The model consists of the piston, piston pin, piston ring, bushing, cylinder liner and connecting rod. The oil film and contact pressure are considered in the contact surfaces between the piston and piston pin, the piston pin and bush, and the piston skirt and cylinder liner. A self-compiled code, which considers the factors of the piston skirt profile and ellipticity, is applied to calculate the initial clearance at the oil film surfaces between the piston and piston pin, the piston pin and bush, and the piston skirt and cylinder liner. The dynamic loads of the piston and connecting rod under the peak torque and peak power cases are calculated using powertrain commercial software, which are then used to carry out the stress and fatigue analyses. Compared with those published in literature, the present model is able to simulate the actual working conditions of the piston more accurately. The model can be used to evaluate and assess the piston skirt pressure, the stress and fatigue life of the concerned areas of the piston. [ABSTRACT FROM AUTHOR]

The transmission distance of DC project is always long, and along the transmission distance, the structure of lines and towers varies according to local environment. It is hard to build a precise harmonic model composed of different sections of line with exact line parameters, so it is important to research the influence of line structure on the harmonic distribution in system and find the key parameters, in order to simplify the model. By building models of different line parameters in harmonic analysis program and calculating, it is found that the line spacing has a strong influence, the influence of height weakens when higher, the earth resistivity, ground wires and conductor type affect little, but the bundle number and spacing affect a lot, especially at low frequency. The influence rules on filter equipment are the same. The EMTPC simulation verified these conclusions. Combined with the practical project design convention, the height is the most important subsection basis. It is verified that a simplified model of a few line sections of different parameters can simulate the harmonics in project exactly. [ABSTRACT FROM AUTHOR]

[ Objective] The aim was to optimize the configuration of seedling density and line spacing of forage sweet sorghum (Sorghum bicolor (L. ) Moench) and explore its high-yield cultivation techniques. [Methods] Effects of such two influencing factors as line spacing ad seedling density on the leaf-stem ratio, DW/FW ratio and grass yield of forage sweet sorghum were analyzed by using split-plot experiment design experiment method and LSD method of IBM. SPSS. Statistics. v22 statistics software. [ Results] Seedling density ad line spacing had no obvious effect on the lea-stem ratio and DW /FW ratio of forage sweet sorghum but had obvious influences on the grass yield. Moreover, the optimal combination of seedling density and line spacing for high yield of forage sweet sorghum was A2B4, that is, seedling density was 225 000 plants/hm², and line spacing was 40 cm. [ Conclusions] The results provided a theoretical basis and technical support for high-yield cullivation techniques of forage sweet sorghum. [ABSTRACT FROM AUTHOR]

Various types of conical picks in different shapes are produced and widely employed on mechanical excavators. Depending on the mechanical and abrasivity properties of rocks, appropriate shape of pick is selected. In order to obtain maximum efficiency from the pick during excavation, the interaction between the pick and rock and the cutting mechanism play very important role. In this context, linear cutting tests were conducted by using a conical pick at the cutting depths between 3 and 18 mm and also at the various line spacings on sandstones exhibiting different mechanical properties. The results indicated that cutting depth and line spacing have significant influences on the tool forces acting on the pick, the ratio of normal to cutting force, and the specific energy. Accordingly, strong correlations and empirical models were developed. In conclusion, the empirical models proposed for estimating the forces and specific energy would be used for producing the conical bits and also designing the cutter heads of mechanical excavators on soft and medium-hard strength sandstones. [ABSTRACT FROM AUTHOR]

An experiment was conducted according to randomized complete design to determine best plant spacing and agronomic traits at research farm PMAS Arid Agriculture University Research Farm Chakwal Road, Rawalpindi, during 2008-2009. Three plant spacing's (5, 10, 15 cm) and three row spacing's (10, 20, 30 cm) comprised of the following treatment combinations (T1= 5?10 cm, T2= 5?20 cm, T3= 5?30 cm, T4= 10?10 cm, T5= 10?20 cm, T6= 10?30 cm, T7= 15?10 cm, T8= 15?20 cm, T9=15?30 cm) under rain-fed conditions. The net plot size was 2?6 m with three replications. Days to emergence, plant height at maturity, number of branches per plant, number of capsules per plant, number of seed per capsule, 1000- seed weight, seed capsule ratio, seed yield per plot, biological yield, harvest index, oil concentration and fresh weight of weeds was observed. All agronomic attributes were significantly effected at 15?30 cm spacing, along with oil concentration and fresh weight of weeds, while 10?10 cm row to row and plant to plant spacing had no significant effect. Plant height (cm), number of capsules per plant was maximum for plant geometry of 15?30 cm and lesser amount of weeds. An increase in row and plant spacing led to significantly higher of branching. Higher plant and row spacing resulted in non- consistent increase in the number of seeds per capsule. Seed yield increased with higher row to row and plant to plant spacings. Yield were lower at the narrow (10?10 cm) row and plant spacing's, compared to higher of 15?30 cm spacing. Thus, it is concluded from this study that Linola should be grown at 300-450 cm grids for higher yield output. [ABSTRACT FROM AUTHOR]

A tunable gas sensor based on an asymmetric external cavity semiconductor lasers oscillating on two spectral lines is presented and investigated experimentally and theoretically. In order to minimize the cost and size of the gas sensor, relative intensity noise (RIN) as a detection methodology is used to measure the intensity levels and intensity differences of two lines. The influence of the spectral separation of the two lines on the RIN has been investigated and explained in the framework of the interplay of the linewidth enhancement factor and two different cavity lengths of the two lines. Each line is related to a different cavity length, which we denote as an asymmetric laser. It has been found that for larger line spacing, the sensor reveals a higher sensitivity to intensity variations of the lines than for smaller line spacing. The experiments show the largest change of RIN at an intensity difference between the two lines of −5 and +5 dB. Very interesting is the experimental result that each line can be tuned in a stable single line condition. For a line intensity ratio between −40 and −15 dB as well as around +20 dB, two ranges of constant RIN have been found, which are different in the averaged RIN by $\approx 6$ up to 10 dB depending on the line separation. The difference of $\approx 6$ up to 10 dB can be quantitatively explained by the asymmetric cavity design and linewidth enhancement factor. [ABSTRACT FROM PUBLISHER]

As a structured document, Braille is the most common means of reading and study for visually handicapped people. The need for converting Braille documents into a computer-readable format has motivated research into the implementation of Braille recognition systems. The main theme of this research is to propose robust probabilistic approaches to different steps of Braille Recognition. The method is meant to be very general in terms of being independent of those parameters of the Braille document such as skewness, scale, and spacing of the page, lines, and characters. For a given Braille document, a statistical method is proposed for estimating the scaling, spacing, and skewness parameters, whereby the detected dots of the Braille document are modeled using a parameterized probability density function. Skewness, scaling, and line spacing are estimated as a solution of a maximum-likelihood (ML) problem, which is solved using expectation maximization. Based on those parameters, each line of the Braille document is extracted, and each of three rows of individual lines is separated based on the vertical projection of the Braille dots. Finally, a scale-independent automatic document gridding procedure is proposed for dot localization and character detection based on a hidden Markov model. [ABSTRACT FROM AUTHOR]

Abstract: The validity of the assumption that an irrigation event from point sources can be approximated as an infinite line source is investigated in this article. This is accomplished by comparing soil water dynamics under line and point sources. Two existing mathematical models which simulate point and line drip irrigation were used. The models consider root water uptake, evaporation of soil water from the soil surface and incorporate hysteresis in the soil water characteristic curve. The comparison was made for two soil types (loamy sand and silt). The results showed that the treatment of a point source as a line source underestimates the water content values for both the soil types. This difference decreases when the depth of comparison increases. For soil depths greater than 30cm and for time greater than irrigation duration the two models gave very close results. For the same emitter spacing and for the horizontal direction perpendicular to the drip line on the emitter spot, when the distance from the point and the line sources increases the difference of water content values increases. On the contrary, in the direction parallel to the drip line when the distance from the emitter increases (the distance from the line source remains the same) the difference of water content decreases. Lastly, differences are greater in the case of coarse grained soil than in fine grained soil. [Copyright &y& Elsevier]

Abstract: This research investigated the effects of text presentation on online behaviour and preferences in order to generate design guidelines for the production of web pages. Previous research has indicated that method of text presentation has a significant impact on usability. The present research found that varying text presentation had a significant effect on task performance, with wider line spacing leading to better accuracy and to faster reaction times. Left-aligned text led to better performance, although participants preferred justified text. Implications of these results for the design of web pages are discussed and recommendations given. [Copyright &y& Elsevier]