The mechanisms,evaluation and estimation of anti-skid performance of snowy and icy pavement:A review

The anti-skid performance of snowy and icy pavements is a popular research topic among road workers.Snow and ice are pollutants on a road surface.They significantly reduce the skid resistance of pavements,and thus,cause traffic accidents.Pertinent research progress on the skid resistance of snowy and icy pavements was reviewed and summarized in this work.The formation and classification of snowy and icy pavements were described on the basis of the state of snow and ice.The friction mechanisms between tires and snowy and icy pavements were revealed.Measurement methods and their applicability to the skid resistance of snowy and icy pavements were summarized.Factors that affect the skid resistance of pavements were discussed from the perspectives of pavement,environment,and vehicle.In addition,models of snowy and icy pavement resistance were classified into experience,mechanical,and numerical models.The advantages and disadvantages of these models were then compared and analyzed.Some suggestions regarding snowy and icy pavements were presented in accordance with the aforementioned information,including the development of efficient testing tools,the quantification of skid resistance under the coupling effects of multiple factors,the establishment of unified evaluation standards,and the development of more effective skid resistance models.

Time consumption,productivity,and cost analysis of skidding in the Hyrcanian forest in Iran

The performance of the skidder Timber jack 450 C was presented in timber skidding of non-coniferous trees in hilly and mountainous conditions. An empirical time study was conducted to evaluate the current skidding system in Hyrcanian forest in northern Irma for improving production rate of skidding and finding out the production cost for planning. Based on the identified elements of skidding work phase and 130 recorded cycles, we calculated the models for effective time consumption, total productivity, and unit cost. The validity of the model was tested at 95% confidence interval. The average load volume per cycle was 2.82 m3, average one way skidding distance was 450 m, and the average slope was 18%. The average travel speed of unloaded skidder was 5.8 km.h-1, and the average speed of loaded skidder was 0.1 km.h＂~ higher than the speed of the unloaded ones. The travel speed was pre- dominantly affected by longitudinal slopes and types of strip roads. The average speed of pulling the cable was 1.16 km.h-1, and that of load winching was 0.74 km.hl. The average outputs in skidding was 10.6 m^-3.h^-1 and the unit cost was 12.1 USS per hour. The time consumption and productivity of skidding depends on distances and slope, number of logs per cycle, volume, log length, etc. However, the influence of variables is not the same.

Design of Small Stone Asphalt Mixture based on Anti-skidding Performance

Small stone asphalt mixture（SSAM） was designed by Bailey method and coarse aggregate voids-filling method.The optimum asphalt content was determined by Marshal test.Surface texture depth for SSAM with different voidage,and the BPN of SSAM and SMA before after wet track abrasion were measured.The experimental results indicate that the surface texture depth increases with the decreasing of asphalt aggregate ratio.The SSAM with the optimal asphalt content has a good skid resistance.BPN of asphalt mixture decreases with the increasing of wearing time,but the extent of reduction is different.The reduction rate of BPN for SSAM is smaller than that of SMA,indicating that SSAM has a good skid resistance attenuation capacity.Finally,the other properties of SSAM are also evaluated,showing that the splitting strength and modulus and SSAM are higher than those of SMA,and the other properties of SSAM,such as high-temperature performance and water stability can also satisfy the technical requirements.

Investigation on Skidding of Rolling Element Bearing in Loaded Zone

Skidding which occurs when rolling element entering into the loaded zone is prone to cause wear and incipient failure to the raceways and rolling elements. This paper presents a dynamic model to investigate the skidding of a rolling element bearing under radial load when the rolling element is entering into the load zone. In this dynamic model, the effects of the contact forces, friction forces on the rolling element-race and rolling element-cage interfaces, gravity, and the centrifugal forces of rolling elements are taken into consideration. The Hertzian contact theory is applied to calculate the non-linear contact forces. The Coulomb friction law is used to calculate the friction forces. The differential equations of rotational motion of the rolling element with regard to its central axis and the central axis of the outer ring are established respectively. The dynamic equations are then solved by using a fourth-order Runge-Kutta algorithm. The skidding characteristics of rolling element at the entry into the loaded zone are exposed, and the effects of the operating parameters on skidding behavior are carefully investigated.

ASSESSMENT OF ANIMAL SKIDDING AND GROUND MACHINE SKIDDING UNDER MOUNTAIN CONDITIONS

The Proportion of animal skidding in forest operations in Heilongjiang forest region increased signiticantly in recent years. This paper at first demonstrated and analyzed the development of the animal skidding and machine skidding, then, evaluated these two means of ground.skidding currently runing in this region both individually and comprehensively under the following criteria: operation efficiency or operation cost, degree of damage to soil and residual stands, accident rate, and natural regeneration. Finally, according to the results of synthetic assessments, cIassitications of operation conditions suitable to each of skidding measures were recommended quqntitatively with considerations of multiple evaluation criteria.

Soil physical properties degrade further on skid trails in the year following operations

Short-term recovery of soil physical properties on skid trails was investigated upon cessation of skidding operations and 1 year later. Bulk density and porosity were assessed at three levels of traffic intensity and two slope gradients. Compared to undisturbed areas, bulk density increased, total porosity and macroporosity decreased, and microporosity increased in the compacted areas immediately after skidding. In all cases, changes were significantly greater when traffic intensity was higher and when slopes were steeper. Surface soil compaction did not show any recovery over the 1-year period, illustrating the persistent effects of compaction on soil structure. In fact, surficial compaction further increased and macroporosity further decreased after 1 year of recovery, compared to immediately after skidding. While these changes may reflect inherent small-scale site variability or differences in soil moisture content at times of sampling, direct negative physical impacts on newly exposed soil（such as by raindrops）, in addition to the loss of organic matter after canopy removal and skidding, likely delayed any physical recovery, particularly on heavily trafficked trails on steeper slopes. These results raise serious concerns about longterm resilience to traffic on forest soils and indicate the necessity to properly retire skid trails to avoid further soil degradation as trails age.

Aircraft Electric Anti-skid Braking System Based on Fuzzy-PID Controller with Parameter Self-adjustment Feature

The principle of electric braking system is analyzed and an anti-skid braking system based on the slip rate control is proposed.The fuzzy-PID controller with parameter self-adjustment feature is designed for the anti-skid braking system.The dynamic model of aircraft ground braking is established in the simulation environment of MATLAB/SIMULINK,and simulation results of dry runway and wet runway are presented.The results show that the fuzzy-PID controller with parameter self-adjustment feature for the electric anti-skid braking system keeps working in the state of stability and the brake efficiencies are increased to 93%on dry runway and 82%on wet runway respectively.

Pavement Friction and Skid Resistance Measurement Methods: A Literature Review

Driving safety is of significance in the automobile industry and transportation systems. Pavement skid resistance has long been recognized as the most important parameter in reducing traffic accidents especially in wet conditions. The knowledge of the friction coefficient and skid resistance is very valuable information for safety enhancement of roads. Thus, it is important to find proper methods for measuring skid resistance and frictional properties of the pavement surface. There is a wide range of measurement methods and devices for measuring skid resistance. This paper presents a review on the research studies that have been done on characterization of the frictional properties of the pavement surface and discussed methods used for measurement and evaluation of texture characteristics and the strengths and weaknesses of these methods. Finally, some ideas have been suggested to develop new methods for better and proper measurement of skid resistance.

Design and Dynamics Analysis of Anti-skid Braking System for Aircraft with Four-wheel Bogie Landing Gears

In asymmetric conditions,the movement and loads of left/right wheels or front/back wheels of the aircraft with multi-wheel or four-wheel bogie landing gears are inconsistent.There are few open literatures related to anti-skid braking system for multi-wheels due to technology blockade.In China,the research on multi-channel control and non-equilibrium regulation has just started,and the design of multi-channel control system for anti-skid braking,the simulation of asymmetry taxiing under braking are not studied.In this paper,a dynamics model of ground movement for aircraft with four-wheel bogie landing gears is established for braking simulation, considering the six-degree-of-freedom aircraft body and the movement of bogies and wheels.A multi-channel anti-skid braking system is designed for the wheels of the main landing gears with four-wheel bogies.The eight wheels on left and right landing gears are divided into four groups,and each group is controlled via one channel.The cross protection and self-locked protection modules are added between different channels.A multi-channel anti-skid braking system with slip-ratio control or with slip-velocity control is established separately.Based on the aircraft dynamics model,aircraft braking to stop with anti-skid control on dry runway and on wet runway are simulated.The simulation results demonstrate that in asymmetric conditions,added with cross protection and self-locked protection modules,the slip-ratio-controlled braking system can automatically regulate brake torque to avoid deep slipping and correct aircraft course.The proposed research has reference value for improving brake control effect on wet runway.

STUDY ON CONTACTING MELTING AND ANTI-SKID TECHNOLOGY FOR A TIRE TRACTION ON ICE

Theoretical analyses and experimental studies of the mechanisms of melting film formation are performed. The results show that frictional heating is the dominant mechanism because temperature behaves in the manner predicted by the theory of frictional heating. A study of the active technology for anti-skid is also made. Conclusions indicate that adjusting tire pneumatic pressure can improve the control stability and the travelling safety of an ice-automobile.

Influence of Thin Water Film on Skid Resistance

Most of past researches on the skid resistance/road wetness relationship deal with thick water depths （〉 1 mm）. Questions remain as to the variation of skid resistance with thin water films and the transition between the dry state and the so-called ＂damp＂ or ＂humid＂ state at which the skid resistance drop can be as high as 30%-40%. This paper deals with a theoretical and experimental assessment of the friction-water depth relationship. The main objective is to estimate local water depths trapped between the tire and the road asperities and to define a so-called ＂critical＂ water depth which can be used to detect risky situations for road users. Tests are performed in laboratory. It was found that the friction-water depth curves have an inverse-S shape and present an initial constant-friction part before decreasing to a minimum value. A ＂critical＂ water depth, defined as the water depth above which the friction coefficient collapses significantly, is determined from surface texture on critical water depth is discussed. observed friction-water depth curves. Influence of test speed and

Residual tree damage along skidding trails in beech stands in Greece

We studied the damage caused to unfelled trees during skidding operations in four beech stands of northern and central Greece that were managed under differing harvesting systems.After timber was harvested we recorded and analyzed all damage to a width of 2 m along both sides of the skid trails.The percentage of damaged residual trees was 17–28 %.Higher numbers of saplings were uprooted or destroyed in parts of the stands with high natural regeneration.Most damaged trees suffered 1.33–1.90 wounds that were inflicted up to a height of 1 m above ground level.At all sites mean wound sizes were large,89–1190 cm2,and caused elevated risk of future fungal infection.The damage caused by skidding during timber harvesting can be minimized by better planning the harvest operations,and training forest workers in reduced impact logging.

Determination and prediction of pavement skid resistance–connecting research and practice

Adequate pavement skid resistance is a key requirement for safe road operations.Unfortunately,the measurement and prediction of the skid resistance property of an in-service road pavement,or pavement mixture specimens in the laboratory,is a highly challenging process from both theoretical and practical points of view.For more than 60 years,owing to the lack of theoretical solutions to the complex tire-fluid-pavement interaction problem,the practice of pavement skid resistance determination and prediction has essentially been derived from experimental and field observed data.The rapid development of efficient numerical computational techniques and high-power computing facilities in the last two decades made it possible for researchers to numerically solve the tire-fluidpavement interaction problem.It enables the numerical evaluation and prediction of high-speed wet skid resistance,and the determination of the tire-pavement kinetic friction coefficient in the evaluation of low-speed skid resistance.This paper presents a state-of-the-art review of the research development of theoretical mechanistic approaches in the determination and prediction of pavement skid resistance.It covers the following main aspects of the subject matter:(i)mechanisms of skid resistance generation in dry,wetted(i.e.,damp),wet and flooded pavements;(ii)theoretical evaluation of pavement skid resistance in dry,wetted,wet and flooded states;(iii)theoretical approaches in pavement skid resistance prediction;and(iv)concepts of representing the skid resistance state of pavement.The capability of finite element simulation approach for wet skid resistance evaluation with good accuracy is explained.Also highlighted is the practical significance of the Concept of Skid Resistance State.Areas of practical applications of the concept,coupled with the simulation model,are introduced.They include applications in driving safety analysis,road safety design and control,design of paving mixtures,safety maintenance and management of pavements,and harmonization of skid resistance measurements and predictions.

Comparison of Skidding Performance of Small Track-type Experimental Prototype Skidder and J-50 Skidding Tractor

In this paper, field experimental comparison is made between a small track-type experimental prototype skidder and a J-50 skidding tractor. Experimental data, including skidding productivity, soil compaction on skidding trails, and damage rate of the residual trees, are analyzed. The results indicate that with the condition of scattered skidding area and low skidding volume per cycle, small track-type experimental prototype skidder has advantage on working and a higher skidding productivity. It makes lower soil compaction to the skidding trails in the depth of 0-5 cm, 5-10 cm, and 10-15 cm. Under the same work conditions, the damage rate of the residual trees made by small track-type experimental prototype skidder is only 1/5 of those made by J-50 type skidding tractor. The damage rate is reduced by 80%.

Influence of Skidding Operation on Forest Soil Respiration for Small Four-wheeled Tractors

The TJSD-750-Ⅱ type compactness measurement instrument and Li-8100 soil carbon flux automatic measurement system are used to measure soil compactness and soil respiration rate at different skidding roads. A regression model is established to analyze the correlation between soil respiration and its influencing factors. The results shows that the soil compaction on the main skidding road and sub skidding roads are larger than the control points, and the soil compaction on the main skidding road is larger than that on sub skidding roads. The higher the soil compactness is, the lower the rate of soil respiration is. This also leads to the lower sensitivity of soil respiration rate influenced by temperature and humidity.

ROV加装SKID后对其作业的影响评估

水下工具模块(SKID)通常使用与水下机器人(ROV)相匹配的连接机构安装于ROV框架底部,用于拓展ROV搭载能力、实现特定功能、存储较大容量的注入剂等,相对于普通ROV外接工具,SKID的整体设计是以ROV的主要参数为依据的,当其安装到ROV上时,能适应ROV收放载荷及水下作业载荷,因此不需要频繁拆卸和安装。因此在深水作业中,除实现自身功能外,SIKD还可以搭载多种ROV外接工具执行作业。然而在加装SIKD之后由于ROV的尺寸、重力、负载等参数发生变化,ROV在作业过程中也有一定的影响。

Engineering Application and Development of Anti-skid Sand

In view of the increasing cement concrete pavement in China,the proportion of road non-slip surface layer is large,the winter slippery performance is insufficient and the later non-slip treatment is difficult. Through the concrete construction and post-application and development of the anti-skid sand in the road and bridge,the feasible anti-skid optimization measures are put forward.

Evaluation of surface textures and skid resistance of pervious concrete pavement

Surface textures had long been recognized as primary factors to provide the skid resistance on pavements; however, no measurement of skid resistance on pervious concrete pavement with various surface texture parameters had been made. Fractal geometry was introduced in the present work to accurately simulate transect contour curves of pervious concrete specimens through fractal interpolation. It is proved that its fractal dimension (D) can be adopted to measure the skid resistance on pervious concrete pavement, overcoming the shortcomings of both macrotexture depth (DT ) and British portable pendulum number (NBP). Combined with Fujikawa-Koike tire/road contact model, the optimization method of all surface textures was recommended for designing and constructing excellently skid-resistant and noise-absorptive pervious concrete pavement. In addition, evaluating of the abrasion process and attenuation of the surface textures on concrete pavement slabs was also the focus of this work based on accelerated abrasion test. Results show that the surface textures on pervious concrete pavement slabs is extremely durable, compared to those on conventional grooved or exposed aggregate concrete pavement slabs.

An Adaptable Walking-skid for Seabed ROV under Strong Current Disturbance

这份报纸建议了一个新概念一能适应腿得多打滑为在高潮汐的电流期间翻新到遥远地操作的车辆(ROV ) 的设计在水下管道检查。为 ROV 的推进器驱动的推进上的唯一的信赖被在走的一只可连接的昆虫形式的一个建议低费用 biomimetic 答案代替打滑。这能适应的走的优点打滑是在在海床环境上放和耐力到强壮的电流的高稳定性。在不同赔偿姿势的skid 附件引起了至少四，这预定的用显示出的 Solidworks 流动模拟的计算机模拟流动研究增加在总的来说拖，并且否定电梯在海床 ROV 上强迫完成一更好在高当前的条件下面调遣并且车站保留(从 0.5 m/s 到 5.0 m/s )。一个图形的用户接口被设计在 robot-in-the-loop 在水池测试和 kinematics 模拟期间与用户一起交往。

Development and Application of the Amphibious Modulized Skid-mounted CTU

This paper mainly introduces the structural composition,operating principle,major technical parameters,design features and technical features of the amphibious modulized skid-mounted coiled tubing unit(CTU).It also describes the experimental condition of this unit and its application in Jidong Oilfield.The unit has been successfully operated in Jidong Oilfield 30 well-times.The maximum lifting or snubbing depth is 2,300 m;the velocity is 15 m/min;the manifold pressure is 20 MPa;the maximum deviation angle is 35.8°.It has successfully realized the modularization of the CTU.The whole system uses an explosion-proof design,which achieves the second class of explosion-proof grade in the oilfield operation area,and gets the explosion-proof certificate and certification of the China Classification Society.It also obtains the marine operation qualification.This paper has a certain referential significance for the CTU's design and research.