Increase Of Horizontal Distance Research Articles

Research On Soil Displacement Prediction Method Caused By High-pressure Jet Grouting Pile Group Construction Under Adjacent Pile Response

This paper analyzes the soil displacement effect during high-pressure jet grouting pile construction by simplifying the construction process as a series of pressure-controlled spherical cavity expansions in a semi-infinite soil medium. Based on the elastic-plastic solution of pressure-controlled spherical cavity expansion theory, a calculation method is proposed to estimate the soil displacement caused by high-pressure jet grouting pile construction. Non-linear contact theory between the pile and soil is introduced, and the finite difference method is employed to determine the internal forces and deformations of the pile. The proposed method is applied to field construction cases, and its validity is verified by comparing the results with on-site monitoring data. The research findings reveal that the soil displacement effect decreases with depth and primarily occurs in shallow soil layers during the construction of individual high-pressure jet grouting piles. The lateral displacement at the ground surface increases first and then decreases with the increase in horizontal distance, while the ground uplift exhibits an exponential decay trend.

Is Quadriceps-Strengthening Exercises (QSE) in Medial-Compartment Knee Osteoarthritis with Neutral and Varus Malalignment a Paradox? - A Risk-Appraisal of Strength-Training on Disease Progression.

The present inquiry seeks to investigate whether the current regimens of QSEs (Quadriceps-Strengthening Exercises) aggravate the disease while mitigating symptoms. A comparative study was conducted on 32 patients with medial compartment osteoarthritis of knees. While the neutral group of 16 patients was constituted of those with an anatomical-lateral-femoro-tibial-angle (aFTA) 176-180º, varus group comprised an equal number of patients with an aFTA >180º. A home-based 12-week strength-training program involving weekly visits to hospital for supervised sessions was administered. The outcome measures were visual-analog-scale (VAS), medial patello-femoral joint tenderness (MPFJT), time-up-and-go-test (TUGT), stair-climb test, step test, WOMAC, IKDC scores, aFTA, hip-knee-ankle (HKA) angle, lateral-tibio-femoral-joint-separation (LTFJS), and horizontal-distance-from-centre-of-knee-to-Mikulicz-line. There was a significant increase in quadriceps strength (p<0.01) in both groups. Values for neutral group with VAS score (p=0.01), MPFJT (p=0.01), TUGT (p=0.01), timing of the stair climb test (p=0.01), WOMAC (p<0.01), and IKDC (p=0.03) were better compared to varus group with VAS score (p=0.13), MPFJT (p=0.03), TUGT (p=0.90), timing of stair climb test (p=0.68), WOMAC (p<0.02), and IKDC (p=0.05). Varus group also showed an increase in aFTA and LTFJS in 12 patients, increase in HKA in 11, and increase in horizontal distance from the centre of knee to the Mikulicz line in 7 patients. The present study brings to the fore the paradoxical role played by QSEs in management of medial knee OA. While there is a radiological progression of the disease in both neutral and varus mal-aligned knees more so in the latter than the former.

Theoretical analysis on horizontal rectification of tunnel near deep foundation pit by grouting

In a city with crowded underground space, the excavation of deep foundation pit leads to excessive displacement of adjacent subways and tunnels, which poses serious threats to the safety of existing tunnel structures. At present, theoretical analysis of the horizontal displacement rectification of tunnel by compaction grouting near a deep foundation pit is rarely reported. In this study, the analytical solution is derived based on the source-source theory and cavity expansion theory for grouting in a quarter-infinite space with a vertical rigid boundary (i.e. a rigid retaining structure). The horizontal displacement of tunnel can be determined onthebasisof the Pasternak foundation beam theory. Then the calculated horizontal displacement of tunnel is validated against the measured results obtained from a tunnel rectification test based on grouting in Tianjin and a rectification engineering in Shenzhen. Based on the theoretical solution proposed in this study, the grouting parameters and modes are optimized to reach a high-efficient rectification. For the single-opening grouting, with the increase of horizontal distance from the grouting tube, the horizontal displacement of soil gets lower and becomes negligible (less than 0.5 mm) at 12 m away from the tube. For the multi-row grouting, the depth of the end of the grouting tube should be reduced for high-efficient rectification.

Simulated climate effect of the Three Gorges Reservoir after its completion:Within surface and local scope instead of regional

针对以往三峡水库气候效应数值模拟研究中,水库参数化方案简约及模拟时段未涉及成库以来高水位运行阶段等不足,在中尺度气象模式中,通过扩宽水体面积和抬升水位高度的方式对三峡水库引起的陆面参数变化进行描述,进而采用敏感性数值试验及统计分析等手段,评估了三峡水库成库以来高温干旱(2013年)和低温洪涝(2020年)年景下,关键气象要素对水库运行的响应特征。结果表明:两种典型年景下水库运行均会造成近地层气温降低(0.98~1.27℃)、相对湿度增加(3.9%~5.5%)和风速增大(0.43~0.68 m/s),同时响应强度的日变化导致近地层气温和相对湿度的日较差减小、平均风速的日较差增大;尽管上述变量的变化幅度与该地区气候的自然变率相当,但水库运行对气温和相对湿度的影响范围基本限制于水库周边约2 km,垂直方向则大多低于200 m,对风速的影响范围可扩展至水库周边约12 km,垂直方向延伸至200 m左右,且响应强度均随水平距离和垂直高度的增加而显著减小。尽管数值试验放大了三峡水库的气候效应,但作为典型的河道型水库,三峡水库成库以来的不同气候年景下,水库运行产生的气候效应基本限制在近地层、局地范围内,未对区域气候产生明显影响。;In view of the shortcomings of the previous numerical simulation research on the climate effect of the Three Gorges Reservoir (TGR), such as the simplicity of the reservoir parameterization and the fact that the simulation period did not involve the reservoir impoundment period, the changes of land surface parameters induced by the TGR were numerically described by increasing the river width and raising the water level in the mesoscale meteorological model. The variation characteristics of meteorological elements after completion of the TGR were analyzed based on two parallel numerical simulations, control run (no TGR) and sensitive run (TGR), during the drought year with high temperature (2013) and the flood year with low temperature (2020). The results show that the operation of TGR under these two typical years both reduce the surface temperature (0.98-1.27℃), increase the relative humidity (3.9%-5.5%) and the wind speed (0.43-0.68 m/s), the diurnal range of near-surface temperature/relative humidity decreases and the diurnal range of wind speed increases with the diurnal variation of the response; Although the aforementioned responses are equivalent to the natural climate variability, the variations of temperature and relative humidity are basically limited to about 2 km around the reservoir, most of which are lower than 200 m in the vertical direction, and the variation of wind speed change extend to about 12 km near the reservoir with up to 200 m in the vertical direction. All of these responses decrease significantly with the increase of horizontal distance and vertical height. Therefore, although the climate effect of the TGR is amplified in our simulation experiment, as a typical river-type reservoir, the climate effect induced by the operation of TGR is basically limited to the surface and local area, and has no obvious influence on the regional climate.

Lightning inductive coupling characteristics of parallel cables: Computation and measurement validation

AbstractA simulation model composed of an interfering cable and a disturbed cable is established for studying the lightning inductive characteristics between parallel cables. Effects of the horizontal distance between cables (5–40 cm), their height difference (−6–32 cm), as well as the length of disturbed cable (1–100 m) are investigated for the cable induced voltage, which is measured at the resistive load connected between one terminal of the disturbed cable and the ground, when various lightning surge currents (8/20 μs, 5/320 μs, and 0.5 μs/100 kHz) are delivered into the interfering cable. Our findings show that an increase of horizontal distance between cables can give rise to an exponential decrease of the cable induced voltage, and that there exist linear correlations between either the height difference of two cables or the length of disturbed cable and the cable induced voltage, which reaches maximum when the cables are located at the same height and of equal length. Verification experiments for the effect of horizontal distance have also been made, and, in general, they all show a reasonable agreement with the simulations. A detailed theoretical explanation of obtained findings is provided as well.

Research on protective mechanism of semicircular arc pre-crack under impact load

In this paper, a plexiglass (PMMA) specimen is designed for dynamic impact testing based on the digital laser dynamic caustics experimental system. The impact of offset distance on dynamic fracture behavior of PMMA specimens with semicircular arc pre-cracks in two different directions is investigated. Research shows that: the pre-crack initiates anew when the horizontal distance between the moving crack and the semicircular arc pre-crack is small. With the increase of horizontal distance, the pre-crack attracts the crack first and then repels it. When the distance reaches a critical threshold, the pre-crack has no considerable effect on the moving crack. The above conclusions are not affected by the direction of the semicircular arc pre-crack. Furthermore, the crack deflection angle and the horizontal offset distance of the two groups of experiments conform to a linear function. When the horizontal offset distance is small, the middle part of the pre-crack initiates again. When the moving crack is outside the arc pre-crack, the medium in the pre-crack is the stress relief zone, according to the numerical data. The ability of the medium to resist impact damage can be effectively boosted by placing acceptable pre-cracks on the medium's periphery.

Research on the horizontal reduction effect of urban roadside green belt on atmospheric particulate matter in a semi-arid area

In this study, the horizontal abatement effects of green belts on atmospheric particulate matter at different horizontal distances and plant community structures were investigated in urban roadside green belts in semi-arid areas.We collected mass concentrations of six types of atmospheric particulate matter (PM) per unit time of PM0.3, PM0.5, PM1.0, PM2.5, PM5.0, and PM10 and various meteorological indices, to compare the horizontal reduction efficiency of different distances and plant community structures on different particle sizes, and to establish a support vector machine model. The results showed that 1) the horizontal abatement efficiency of green belts was different for six particle sizes, while the horizontal abatement rate strengthened as the particle size increased. The abatement rate was significantly correlated with microclimatic factors such as temperature and humidity, but less correlated with wind speed. 2) The horizontal abatement rate of roadside green belts on atmospheric particulate matter varies with the increase of horizontal distance in a "single-peak" or "double-peak" pattern, with the best abatement effect of green belts on each particle size at a horizontal distance of 45m. Among the four types of plant community structures, the strongest abatement ability was in the arbor-shrub-herb structure. 3) The correctly tuned prediction model, based on Support Vector Machines, resulted in better horizontal abatement ability of green belts on atmospheric PM. The prediction results showed that the average horizontal abatement rate has the best abatement effect at 45–55 m, peaked at 50 m, and formed stagnant dust at 65 m. In the design of urban road green spaces in semi-arid areas, to achieve the best dust retention effect, the green belt width should be ≥40 m and it is desirable to choose arbor-shrub-herb structures. This study provides a design basis and theoretical support for urban road green space planning in semi-arid areas.

Research on the Influence of Atmospheric Vertical Refraction on Trigonometric Leveling Survey in Qinling Mountains

Atmospheric refraction error is one of the main factors affecting the accuracy of precision trigonometric levelling. The influence of it on height difference rises sharply with the increase of horizontal distance. In this paper, the elevation control survey data of Qinling mountains is used to calculate the atmospheric refraction coefficients among the areas in winter and summer, using the method of geometric levelling inverse calculation. Through the analysis of the change law of atmospheric refractive coefficient, the influence of atmospheric vertical refractive coefficient on trigonometric levelling in the Qinling Mountains is summarized, which provides a reference for trigonometric levelling in similar environments.

Experimental investigation on a loop thermosyphon with evaporative condenser for free cooling of data centers

Integrating evaporative cooling with loop thermosyphon can significantly improve the free cooling ability. In this paper, a loop thermosyphon with evaporative condenser is investigated experimentally. The mist water flow out of a single nozzle is observed and analyzed. The performance and annual free cooling potential of the system are investigated, compared with conventional loop thermosyphon. The results show that the evaporative cooling effect of the locations below the horizontal level of the nozzle is more significant due to gravity. With the increase of horizontal distance from the nozzle, the temperature decreases and then increases and the optimal distance is 200–400 mm. The heat capacity of LTEC increases with the increase of indoor and outdoor temperature difference while it decreases with the increase of humidity. Evaporative cooling can enhance the heat transfer of LTEC by 7%–33% compared with loop thermosyphon with conventional condenser, and this value is larger for smaller indoor and outdoor temperature difference and higher indoor temperature. LTEC can expand the annual free cooling time by 7%–14% compared with LTCC and the effect is more significant in regions with drier weather.

Structure Parameter Optimization of Welding Spot of Corrugated Plate Component

A simple model is used to determine the research route of corrugated plate component with good fatigue life based on equivalent stress, and the simulation results are proved to be reasonable by physical test. It is found that the equivalent stress of corrugated plate component increases with the increase of horizontal distance between welding points during single-row welding, after the analysis of the simulation results. In all the arrangement forms, the number of welding points arranged in triangle arrangement is large, which has good connection effect on corrugated plate component and good structural stability. Therefore, it is better to connect corrugated plate component in a way of welding in row 3, with a distance of 2 mm from top to bottom, a distance of 10 mm from left and right sides of row 1 and row 3, and a distance of 37.2 mm from left and right sides of row 2. The fatigue life simulation result of corrugated plate component under the structural parameters is 7.89e6 times, and the actual fatigue life of physical test exceeded 3.0e7 times, meeting the working condition requirements.

Study on the interference between parallel pipelines and optimized operation for the cathodic protection systems

Purpose In recent years, the demand for oil and gas pipelines has increased rapidly. Due to the restrictions of the pipeline routing, pipelines are generally laid in parallel or in the same trench, which results in stray-current interference between the independent cathodic protection (CP) systems. The purpose of this paper is to study the interference between the long-distance parallel pipelines and to obtain the optimized operation for the CP systems. Design/methodology/approach In this study, first, the numerical model of parallel pipelines was established using the boundary element analysis software (BEASY). Second, the effects of horizontal distance between parallel pipelines, coating damage rate, soil conductivity and anode output current on the interference of parallel pipelines were studied. Finally, by varying the layout or the output currents of CP stations, an optimized operation scheme osf long-distance parallel pipelines was put forward. Findings Simulation results showed that with a decrease in soil conductivity or coating damage rate, the interference increased. Moreover, the interference decreased with an increase in horizontal distance between two parallel pipelines or a decrease in anode output current. It was found that there are three methods to reduce the interference between long-distance parallel pipelines: to reduce the output currents of CP stations, combined protection and to close part of the CP stations. Among them, to close part of CP stations was the optimized scheme because of the lowest operating and maintenance cost. Originality/value The optimized operation scheme proposed in this study can not only solve the interference between parallel pipelines but also provide guidance for the parallel pipelines to be built in the future. Reasonably arranging the cathodic protection stations using numerical simulation can avoid the interference in the cathodic protection systems, and reduce the construction cost.

Numerical Simulation of the Vegetation Effect on Tailing Sand Atmospheric Transport in Uranium Tailing Impoundment

For two conditions of (non-) vegetation cover in uranium tailings beach face, the concentration distribution and settlement regularity of tailing sand with diameter of 10μm at speed of 0.5, 1, 2, and 4 m/s was studied by numerical simulation method. Results shows, with the increase of wind speed and migration distance, particle concentration decreases. Compared with the non-vegetation cover condition, particles concentration in the condition of with vegetation cover is significantly higher than the condition that without vegetation cover; but along with the increase of horizontal distance, the concentration lowers than the latter gradually.

Geochemical characteristics of heavy metals in riparian sediment pore water of Songhua River, Northeast China

This study reports the geochemical characteristics of zinc (Zn), copper (Cu), lead (Pb), nickel (Ni), mercury (Hg), iron (Fe), and manganese (Mn) in the riparian sediment pore water of the Songhua River, Northeast China. In total, 36 pore water samples and 18 surface water samples from three typical sections were collected and analyzed in June 2009. Cluster analysis of heavy metals was performed to analyze the pollution sources of the metals. Results showed that Hg concentrations in the pore water were greater than those in the surface water, indicating a potential ability of Hg release from riparian sediment system to river water. However, concentrations of Fe and Mn in the surface water were greater than those in the pore water, demonstrating that the microenvironments of riparian and riverbed sediment systems were quite different. Variations of Zn, Cu, Pb and Ni between the surface and the pore water were different in each section. Most metals had similar horizontal and profile distribution characteristics in the three sections except for Zn and Ni. Hg, Fe and Mn concentrations in the pore water increased gradually with the increase in horizontal distance from water body, in contrast to this, Cu decreased, and Pb presented a fluctuating trend. With the increase in depth, Pb and Fe, Cu and Mn showed the same trends, and Hg showed a variable trend. The above distribution characteristics could mainly be attributed to the properties and the interactions of metals, pH and oxidation-reduction conditions, and the complex pollution sources and hydrologic regime in history. The probable sources of metals include the historical and ongoing discharge of industrial wastewater, mining activities, sewage irrigation for agricultural production, and atmospheric deposition from coal-fired plants.

Numerical Study of Natural Convection from Two Parallel Horizontal Cylinders Enclosed by Circular Cylinder

In this paper, numerical solution is presented for the steady state, two dimensional natural convection heat transfer from two parallel horizontal cylinders enclosed by circular cylinder. The inner cylinders are heated and maintained at constant surface temperature, while the outer cylinder is cooled at constant surface temperature. Boundary fitted coordinate system is used to solve governing equations. The vorticity-stream function and energy equations is solved using explicit finite deference method and stream function equation solved by successive iteration method. (20)Deferent cases are studied cover rang of Rayleigh number from (1,000) to (25,000) based on the inner cylinder diameter. These cases study the effect of the varying inner cylinders position horizontally and vertically within outer cylinder on the heat transfer and buoyancy that causes the flow. Outputs are displayed in terms of streamline, isothermal contours and local and average Nusselt number. The results showed that the position of the inner cylinders highly affects the heat transfer and flow movements in the gap. At low Rayleigh numbers the average Nusselt number increases with increase of horizontal distance between inner cylinders but the state is reversed at high Rayleigh numbers, while the average Nusselt number is increases with inner cylinder moving down at all Rayleigh numbers. The optimal position of inner cylinders for maximum and minimum heat transfer is located at each Rayleigh number so can be employed in isolation process or cooling process.

NUMERICAL STUDY OF NATURAL CONVECTION FROM TWO PARALLEL HORIZONTAL CYLINDERS ENCLOSED BY CIRCULAR CYLINDER

In this paper, numerical solution is presented for the steady state, two dimensional natural convection heat transfer from two parallel horizontal cylinders enclosed by circular cylinder. The inner cylinders are heated and maintained at constant surface temperature, while the outer cylinder is cooled at constant surface temperature. Boundary fitted coordinate system is used to solve governing equations. The vorticity-stream function and energy equations is solved using explicit finite deference method and stream function equation solved by successive iteration method. (20)Deferent cases are studied cover rang of Rayleigh number from (1,000) to (25,000) based on the inner cylinder diameter. These cases study the effect of the varying inner cylinders position horizontally and vertically within outer cylinder on the heat transfer and buoyancy that causes the flow. Outputs are displayed in terms of streamline, isothermal contours and local and average Nusselt number. The results showed that the position of the inner cylinders highly affects the heat transfer and flow movements in the gap. At low Rayleigh numbers the average Nusselt number increases with increase of horizontal distance between inner cylinders but the state is reversed at high Rayleigh numbers, while the average Nusselt number is increases with inner cylinder moving down at all Rayleigh numbers. The optimal position of inner cylinders for maximum and minimum heat transfer is located at each Rayleigh number so can be employed in isolation process or cooling process.

The effects of ergonomic interventions on low back moments are attenuated by changes in lifting behaviour

This study investigated the effects of ergonomic interventions involving a reduction of the mass (from 16 to 11 and 6 kg) and an increase in the initial lifting height (from pallet height to 90 cm above the ground) of building blocks in a mock-up of an industrial depalletizing task, investigating lifting behaviour as well as low back moments (calculated using a 3-D linked segment model). Nine experienced construction workers participated in the experiment, in which they removed building blocks from a pallet in the way they normally did during their work. Most of the changes in lifting behaviour that were found would attenuate the effect of the investigated interventions on low back moments. When block mass was reduced from 16 to 6 kg, subjects chose to lift the building block from a 10 (SD 10) cm greater distance from the front edge of the pallet and with a 100 (SD 66) degrees/s2 higher trunk angular acceleration. When initial lifting height was increased, subjects chose to shift the building blocks less before actually lifting them, resulting in a 10.7 (SD 10) cm increase in horizontal distance of the building blocks relative to the body at the instant of peak net total moment. Despite these changes in lifting behaviour, the investigated ergonomic interventions still reduced the net total low back moment (by 4.9 (SD 2.0) Nm/kg when block mass was reduced and 53.6 (SD 41.0) Nm when initial lifting height was increased).

Artificially triggered lightning and its characteristic discharge parameters in two severe thunderstorms

The lightning-induced-damages in the mid-latitude regions are usually caused during severe thunderstorms. But the discharge parameters of natural lightning are difficult to be measured. Five lightning flashes have been artificially triggered with the rocket-wire technique during the passage of two severe thunderstorms. The discharge current and close electric field of return stroke in artificially triggered lightning have been obtained in microsecond time resolution by using current measuring systems and electric field change sensors. The results show that the five triggered lightning flashes include 1 to 10 return strokes, and the average return stroke current is 11.9 kA with a maximum of 21.0 kA and a minimum of 6.6 kA, similar to the subsequent return strokes in natural lightning. The half peak width of the current waveform is 39 μs, which is much larger than the usual result. The peak current of stroke Ip (kA) and the neutralized charge Q(C) has a relationship of Ip = 18.5Q0.65. The radiation field of return stroke is 5.9 kV·m−1 and 0.39 kV·m−1 at 60 m and 550 m, respectively. The radiation field decreases as r−1.119 with increase of horizontal distance r from the discharge channel. Based on the well-accepted transmission line model, the speed of return stroke is estimated to be about 1.4×108 m·s−1, with a variation range of (1.1–1.6)×108 m·s−1. Because of the similarities of the triggered lightning and natural lightning, the results in this article can be used in the protection design of natural lightning.

Distribution and Composition of Microbial Populations in a Landfill Leachate Contaminated Aquifer (Grindsted, Denmark).

> Abstract To investigate whether landfill leachates affected the microbial biomass and/or community composition of the extant microbiota, 37 samples were collected along a 305-m transect of a shallow landfill-leachate polluted aquifer. The samples were analyzed for total numbers of bacteria by use of the acridine orange direct count method (AODC). Numbers of dominant, specific groups of bacteria and total numbers of protozoa were measured by use of the most probable number method (MPN). Viable biomass estimates were obtained from measures of ATP and ester-linked phospholipid fatty acid (PLFA) concentrations. The estimated numbers of total bacteria by direct counts were relatively constant throughout the aquifer, ranging from a low of 4.8 x 10(6) cells/g dry weight (dw) to a high of 5.3 x 10(7) cells/g dw. Viable biomass estimates based on PLFA concentrations were one to three orders of magnitude lower with the greatest concentrations (up to 4 x 10(5) cells/g dw) occurring at the border of the landfill and in samples collected from thin lenses of clay and silt with sand streaks. Cell number estimates based on ATP concentrations were also found to be lower than the direct count measurements (<2.2 x 10(6) cells/g dw), and with the greatest concentrations close to the landfill. Methanogens (Archaea) and reducers of sulfate, iron, manganese, and nitrate were all observed in the aquifer. Methanogens were found to be restricted to the most polluted and reduced part of the aquifer at a maximum cell number of 5.4 x 10(4) cells/g dw. Populations of sulfate reducers decreased with an increase in horizontal distance from the landfill ranging from a high of 9.0 x 10(3) cells/g dw to a low of 6 cells/g dw. Iron, manganese, and nitrate reducers were detected throughout the leachate plume all at maximum cell numbers of 10(6) cells/g dw. Changes in PLFA profiles indicated that a shift in microbial community composition occurred with increasing horizontal distance from the landfill. The types and patterns of lipid biomarkers suggested that increased proportions of sulfate- and iron-reducing bacteria as well as certain microeukaryotes existed at the border of the landfill. The presence of these lipid biomarkers correlated with the MPN results. There was, however, no significant correlation between the abundances of the specific PLFA biomarkers and quantitative measurements of redox processes. The application of AODC, MPN, PLFA, and ATP analyses in the characterization of the extant microbiota within the Grindsted aquifer revealed that as distance increased from the leachate source, viable biomass decreased and community composition shifted. These results led to the conclusion that the landfill leachate induced an increase in microbial cell numbers by altering the subsurface aquifer so that it was conducive to the growth of methanogens and of iron-and sulfate-reducing bacteria and fungi.