Search results for: skidding

Authors: Mahdieh Zamzamzadeh, Ahmad Abdullah Saifizul, Rahizar Ramli

Abstract:

The road accidents involving heavy vehicles have been showing worrying trends and, year after year, have increased the concern and awareness levels on safety of roads and transportations especially in developing countries like Malaysia. Statistics of road crashes continue to show that there are many contributing factors on the capability of a heavy vehicle to stop on safe distance and ultimately prevent traffic crashes. However, changes in the road condition due to weather variations and the vehicle dynamic specifications such as loading conditions and speed are the main risk factors because they will affect a heavy vehicle’s braking performance due to losing control and not being able to stop the vehicle, and in many cases will cause wheel lock up and accordingly skidding. Predicting heavy vehicle skidding distance is crucial for accident reconstruction and roadside safety engineers. Despite this, formal tools to study heavy vehicle skidding distance before stopping completely are totally limited, and most researchers have only considered braking distance in their studies. As a possible new tool, this work presents the iterative use of vehicle dynamic simulations to study heavy vehicle-roadway interaction in order to predict wheel lock up effects on skidding distance and safety. This research addresses the influence of the vehicle and road conditions on skidding distance after wheel lock up and presents a precise analysis of skidding phenomenon. The vehicle speed, vehicle loading condition and road friction parameters were all varied in a simulation-based analysis. In order to simulate the wheel lock up situation, a heavy vehicle model was constructed and simulated using multibody vehicle dynamics simulation software, and careful analysis was made on the conditions which caused the skidding distance to increase or decrease through a method using to predict skidding distance as part of braking distance. By applying many simulations, the results were quite revealing relation between the heavy vehicles loading condition, various sets of speed and road coefficient of friction and their interaction effect on the skidding distance. A number of results are presented which illustrate how the heavy vehicle overloading can seriously affect the skidding distance. Moreover, the results of simulation give the skid mark length, which is a necessary input data during accident reconstruction involving emergency braking.

Keywords: accident reconstruction, Braking, heavy vehicle, skidding distance, skid mark, wheel lock up

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Authors: Meiyuan Zheng, Jingwu He, Yuexi Xiong

Abstract:

A universal multi-function leaf spring main landing gear was designed for light aircraft. The main landing gear combined with the leaf spring, skidding, and wheels enables it to have a good takeoff and landing performance on various grounds such as the hard, snow, grass and sand grounds. Firstly, the characteristics of different landing sites were studied in this paper in order to analyze the load of the main landing gear on different types of grounds. Based on this analysis, the structural design optimization along with the strength and stiffness characteristics of the main landing gear has been done, which enables it to have good takeoff and landing performance on different types of grounds given the relevant regulations and standards. Additionally, the impact of the skidding on the aircraft during the flight was also taken into consideration. Finally, a universal multi-function leaf spring type of the main landing gear suitable for light aircraft has been developed.

Keywords: landing gear, multi-function, leaf spring, skidding

Procedia PDF Downloads 268

Authors: A. Rahim Baharudin, Nor Arinee binti Mat Saaud, Muhammad Afiq Azman, Farah Adiba A. Sani

Abstract:

Objectives: This paper shares the case study on the engineering analysis, data analysis, and real-time data comparison for qualifying the stand wires' minimum breaking load and safe working load upon loadout operation for a new project and, at the same time, eliminate the risk due to discrepancies and unalignment of COMPANY Technical Standards to Industry Standards and Practices. This paper demonstrates “Lean Construction” for COMPANY’s Project by sustaining fit-for-purpose Technical Requirements of Loadout Strand Wire Factor of Safety (F.S). The case study utilizes historical engineering data from a few loadout operations by skidding methods from different projects. It is also demonstrating and qualifying the skidding wires' minimum breaking load and safe working load used for loadout operation for substructure and other facilities for the future. Methods: Engineering analysis and comparison of data were taken as referred to the international standard and internal COMPANY standard requirements. Data was taken from nine (9) previous projects for both topsides and jacket facilities executed at the several local fabrication yards where load out was conducted by three (3) different service providers with emphasis on four (4) basic elements: i) Industry Standards for Loadout Engineering and Operation Reference: COMPANY internal standard was referred to superseded documents of DNV-OS-H201 and DNV/GL 0013/ND. DNV/GL 0013/ND and DNVGL-ST-N001 do not mention any requirements of Strand Wire F.S of 4.0 for Skidding / Pulling Operations. ii) Reference to past Loadout Engineering and Execution Package: Reference was made to projects delivered by three (3) major offshore facilities operators. Strand Wire F.S observed ranges from 2.0 MBL (Min) to 2.5 MBL (Max). No Loadout Operation using the requirements of 4.0 MBL was sighted from the reference. iii) Strand Jack Equipment Manufacturer Datasheet Reference: Referring to Strand Jack Equipment Manufactured Datasheet by different loadout service providers, it is shown that the Designed F.S for the equipment is also ranging between 2.0 ~ 2.5. Eight (8) Strand Jack Datasheet Model was referred to, ranging from 15 Mt to 850 Mt Capacity; however, there are NO observations of designed F.S 4.0 sighted. iv) Site Monitoring on Actual Loadout Data and Parameter: Max Load on Strand Wire was captured during 2nd Breakout, which is during Static Condition of 12.9 MT / Strand Wire (67.9% Utilization). Max Load on Strand Wire for Dynamic Conditions during Step 8 and Step 12 is 9.4 Mt / Strand Wire (49.5% Utilization). Conclusion: This analysis and study demonstrated the adequacy of strand wires supplied by the service provider were technically sufficient in terms of strength, and via engineering analysis conducted, the minimum breaking load and safe working load utilized and calculated for the projects were satisfied and operated safely for the projects. It is recommended from this study that COMPANY’s technical requirements are to be revised for future projects’ utilization.

Keywords: construction, load out, minimum breaking load, safe working load, strand jacking, skidding

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Authors: Juang R. Matangaran, Qi Adlan

Abstract:

Industrial plantation forest in Indonesia was developed in 1983, and since then, several companies have been successfully planted a total area of concessionaire approximately 10 million hectares. Currently, these plantation forests have their annual harvesting period. In the timber harvesting process, amount part of the trees generally become logging residue. Tree parts such as branches, twigs, defected stem and leaves are unused section of tree on the ground after timber harvesting. The use of heavy machines in timber harvesting area has caused damage to the forest soil. The negative impact of such machines includes loss of topsoil, soil erosion, and soil compaction. Forest soil compaction caused reduction of forest water infiltration, increase runoff and causes difficulty for root penetration. In this study, we used logging residue as soil covers on the passages passed by skidding machines in order to observe the reduction soil compaction. Bulk density of soil was measured and analyzed after several times of skidding machines passage on skid trail. The objective of the research was to analyze the effect of logging residue on reducing soil compaction. The research was taken place at one of the industrial plantation forest area of South Sumatra Indonesia. The result of the study showed that percentage increase of soil compaction bare soil was larger than soil surface covered by logging residue. The maximum soil compaction occurred after 4 to 5 passes on soil without logging residue or bare soil and after 7 to 8 passes on soil cover by logging residue. The use of logging residue coverings could reduce soil compaction from 45% to 60%. The logging residue was effective in decreasing soil disturbance of timber harvesting at the plantation forest area.

Keywords: bulk density, logging residue, plantation forest, soil compaction, timber harvesting

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Authors: Di Han, Lingfeng Li

Abstract:

Selection of low-temperature separation dehydration and dehydrochlorination process applicable to skid design, using Hysys software to simulate the low-temperature separation dehydration and dehydrochlorination process under different refrigeration modes, focusing on comparing the refrigeration effect of different refrigeration modes, the condensation amount of hydrocarbon liquids and alcoholic wastewater, as well as the adaptability of the process, and determining the low-temperature separation process applicable to the natural gas dehydration and dehydrochlorination skid into the design of skid; and finally, to carry out the CNG recycling process calculations of the processed qualified natural gas and to determine the dehydration scheme and the key parameters of the compression process.

Keywords: skidding, dehydration and dehydrochlorination, cryogenic separation process, CNG recovery process calculations

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Authors: Saleh Kasiri Bidhendi, Shiva Tashakori

Abstract:

With the increasing application of six-wheel robots in various industries, including agriculture and environmental monitoring, there is a growing demand for efficient and reliable control systems that can improve manoeuvrability and at the same time reduce energy consumption. Moving on uneven terrains, various factors such as obstacles or soil heterogeneity can cause the robot to slip. There is limited research addressing this issue. Although the robot is supposed to track a predetermined path, sudden lateral deviation necessitates path planning. To further address this issue, explicit steering is added by activating actuators on steerable wheels, while the SMC controller still commands differential traction forces on all wheels. This integration improves energy efficiency and obstacle traversability while maintaining the merits of skid-steering, such as tight turning manoeuvrability. However, achieving the desired steer angles presents certain challenges. Inverse kinematics was initially employed to achieve the needed steering angles from the desired position, but this approach led to excessive steering without yawing the body. Switching to desired velocity values instead of position limited over-steering but caused zero lateral velocity on horizontal paths, which was problematic for unforeseen skidding. To overcome this, a proportional controller has been employed, using lateral error as its input and providing a proportional yaw angle as output, the P-controller contributes to modifying the steering angles. The controller's robustness has been verified through sensitivity analyses under critical speeds and turning radius conditions. Our findings offer valuable insights into designing more efficient steering controls for rocker-bogie mechanisms in challenging situations, emphasizing the importance of reducing energy¬ consumption.

Keywords: six-wheel robots, inverse kinematics, integrated steering, path following, manoeuvrability, energy efficiency, uneven terrains

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Authors: Kazushige Wada, Mayuko Ueda

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In the present study, we reanalyzed lapse errors in the last phase of a job, by re-counting near lapse errors and increasing the number of participants. We also examined the results of this study from the perspective of prospective memory (PM), which concerns future actions. This study was designed to investigate whether perceiving the importance of PM tasks caused lapse errors in the last phase of a job and to determine if such errors could be explained from the perspective of PM processing. Participants (N = 34) conducted a computerized clicking task, in which they clicked on 10 figures that they had learned in advance in 8 blocks of 10 trials. Participants were requested to click the check box in the start display of a block and to click the checking off box in the finishing display. This task was a PM task. As a measure of PM performance, we counted the number of omission errors caused by forgetting to check off in the finishing display, which was defined as a lapse error. The perceived importance was manipulated by different instructions. Half the participants in the highly important task condition were instructed that checking off was very important, because equipment would be overloaded if it were not done. The other half in the not important task condition was instructed only about the location and procedure for checking off. Furthermore, we controlled workload and the emotion of surprise to confirm the effect of demand capacity and attention. To manipulate emotions during the clicking task, we suddenly presented a photo of a traffic accident and the sound of a skidding car followed by an explosion. Workload was manipulated by requesting participants to press the 0 key in response to a beep. Results indicated too few forgetting induced lapse errors to be analyzed. However, there was a weak main effect of the perceived importance of the check task, in which the mouse moved to the “END” button before moving to the check box in the finishing display. Especially, the highly important task group showed more such near lapse errors, than the not important task group. Neither surprise, nor workload affected the occurrence of near lapse errors. These results imply that high perceived importance of PM tasks impair task performance. On the basis of the multiprocess framework of PM theory, we have suggested that PM task performance in this experiment relied not on monitoring PM tasks, but on spontaneous retrieving.

Keywords: prospective memory, perceived importance, lapse errors, multi process framework of prospective memory.

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Authors: Fentahun Ayu Muche, Yonas Mitiku Degu

Abstract:

Ethiopian farmers traditionally sow Teff seeds using the broadcasting method. However, row sowing offers higher grain yields compared to broadcasting. Despite being introduced to row sowing techniques, many farmers prefer broadcasting due to its simplicity; without proper technology, row sowing is time-consuming, labor-intensive, and physically demanding. The use of suitable row Teff seeder technologies can save time, reduce labor requirements, facilitate weed control, and increase productivity. Unfortunately, previously promoted technologies have not gained significant acceptance due to various limitations. The Agricultural Bureau of the Amhara Region, Ethiopia, has confirmed that row sowing technology significantly improves productivity, yielding results up to twice as high as traditional sowing methods. This innovative approach offers a feasible solution for enhancing Teff production in Ethiopia, contributing to greater precision and efficiency in farming practices. This research aims to design, fabricate, and test a Teff seed-cum-fertilizer drill while addressing the shortcomings of earlier technologies. During the conceptual design phase, eight alternatives were proposed, with the rail-type row Teff seed-cum-fertilizer drill selected for its technical and economic feasibility. The chosen design features five rows with adjustable spacing between 15 cm and 25 cm. It also includes an interchangeable metering mechanism for seeding rates of 5 kg/hectare and 10 kg/hectare. A key focus was placed on the metering mechanism to eliminate power transmission via ground traction, thereby mitigating performance issues caused by wheel skidding. The new design uses pinions that roll over two parallel racks suspended by four posts to transmit motion to the metering unit. Detailed analysis of the selected concept and working mechanism was conducted, and the prototype was manufactured according to specifications from the detailed design. Laboratory and field tests of the fabricated prototype demonstrated good metering mechanism efficiency, with no significant differences between rows. However, the performance of the Teff seed-cum-fertilizer drill is highly sensitive to the seed level in the hopper. Therefore, maintaining the recommended seed level is crucial for ensuring uniform seed distribution during farm operations.

Keywords: row teff planter, disc metering, scoop metering, rack and pinion, fertilizer applicator, seed drill

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Authors: Andrea Bertocchi, Alessio Barnaba Di Fonzo, Davide Talarico, Simone Rivaroli, Jeff Konin

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The patient is a 89 years old male (180cm/85kg) retired notary former golfer with no past medical history. He describes a progressive ideomotor slowdown for 14 months. The disorder is characterized by short-term memory deficits and, for some months, also by unstable walking with a broad base with skidding and risk of falling at directional changes and urinary urgency. There were also episodes of aggression towards his wife and staff. At the time, the patient takes no prescribed medications. He has difficulty eating, dressing, and some problems with personal hygiene. In the initial visit, the patient was alert, cooperating, and performed simple tasks; however, he has a hearing impairment, slowed spontaneous speech, and amnestic deficit to the short story. Ideomotor apraxia is not present. He scored 20 points in the MMSE. From a motor function, he has deficits using Medical Research Council (MRC) 3-/5 in bilateral lower limbs and requires maximum assistance from sit to stand with existing premature fatigue. He’s unable to walk for about 1 month. Tremors and hypertonia are absent. BERG was unable to be administered, and BARTHEL was obtained 45/100. An Amyloid Angiopathy is suspected and then confirmed at the neurological examination. Therehabilitation objectives were the recovery of mobility and reinforcement of the UE/LE, especially legs, for recovery of standing and walking. The cognitive aspect was also an essential factor for the patient's recovery. The literature doesn’t demonstrate any particular studies regarding motor and cognitive rehabilitation on this pathology. Failing to manage his attention on exercise and tending to be disinterested and falling asleep constantly, we used golf-specific gestures to stimulate his mind to work and get results because the patient has memory recall of golf related movement. We worked for 4 months with a frequency of 3 sessions per week. Every session lasted for 45 minutes. After 4 months of work, the patient walked independently with the use of a stick for about 120 meters without stopping. MRC 4/5 AI bilaterally andpostural steps performed independently with supervision. BERG 36/56. BARTHEL 65/100. 6 Minutes Walking Test (6MWT), at the beginning, it wasn’t measurable, now, he performs 151,5m with Numeric Rating Scale 4 at the beginning and 7 at the end. Cognitively, he no longer has episodes of aggression, although the short-term memory and concentration deficit remains. Amyloid Angiopathy is a mix of motor and cognitive disorder. It is worth the thought that cerebral amyloid angiopathy manifests with functional deficits due to strokes and bleedings and, as such, has an important rehabilitation indication, as classical stroke is not associated with amyloidosis. Exploring the motor patterns learned at a young age and remained in the implicit and explicit memory of the patient allowed us to set up effective work and to obtain significant results in the short-middle term. Surely many studies will still be done regarding this pathology and its rehabilitation, but the importance of the cognitive sphere applied to the motor sphere could represent an important starting point.

Keywords: amyloid angiopathy, cognitive rehabilitation, golf, motor disorder

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