Load Handling Research Articles

Failure analysis and repair of the telescopic beam belonging to the spreader of a reach stacker for port operations

Reach stackers land equipment operating in ports of the Colombian Caribbean, are subject to several critical working conditions such as; corrosive environment, excess working hours, overload and lack of predictive maintenance. This work focuses on the failure analysis and the elaboration of the welding repair procedure of the telescopic beam belonging to the spreader of a Reach stacker that operates in a Colombian Caribbean seaport. Initially the fault zone was characterized; by mean a metallographic analysis and a hardness profile to identify the type of structural steel of which the beam is composed, obtaining an A514 grade C of 110KSI of tensile strength and 34HRC of hardness. The equipment manufacturer was verified and the established by the laboratory tests was corroborated. After identifying the material, the fracture area was analyzed where patterns of beach markings were found, typical of a fatigue failure which extended from the circumference of separating pins to the surface of the beam. The inclusion of the separators in the initial design generates stress concentrators in the welding of the pins which increases the fatigue zone combined with the excess load with which the equipment works. This fact could be verified with a technical bulletin published by the manufacturer brand "Taylor" where it indicates this type of failure for the telescopic beam of the Reach stackers. Successively, an FCAW type welding repair procedure is developed in accordance with AWS code D1.1, where the electrode to be used, the cords to be applied, the preheating, and the speeds and conditions recommended for filling the materials are selected cracks. Finally it could be concluded that the fault was generated by fatigue and overload in the welding of the telescopic beam separator pins and its repair will be carried out according to a welding procedure of the AWS code D1.1. The analysis of these types of cases will allow the company to take actions to minimize the new occurrence of the failure such as periodic reviews in that area after the work hours recommended by the manufacturer and the awareness of the equipment operators with the handling of loads on the dock.

Prevalence of Musculoskeletal Disorders among Stone Polishing Workers u sing Stone Polishing Devices in Unorganized Sector of Guwahati India

Stone polishing is one of the prominent informal sector in India (and world as well), where a large number of stone polisher works for long duration. Stone polishing workers manually operate the polishing machine either in standing or sitting position to carry out polishing activities, and are quite prone to various MSDs (repetitive strain induced) and thereby injuries and accidents. The present research therefore intends to explore the occurrences of WMSDs among the stone-polishing workers, and with utmost attempt to put forward some recommendations regarding corrective measures. Thirty (30) male stone polishing workers were selected from the Guwahati city of Assam. A comprehensive study on discomfort feeling was carried out by the modified Nordic questionnaire which considered the information about work nature and job stress. Rapid Entire Body Assessment (REBA) method was followed to evaluate whole body postural load and risks associated with the job. The finding of the study contributes to the understanding of the working conditions of the stone polishing workers and their physical discomforts at various body parts (mainly the lower back, knees and shoulder) due to awkward posture, repetitive motion, force exertion and sustained load handling during polishing activities. To overcome the problem arisen from aforesaid ergonomic stressors associated with stone-polishing work, ergonomic design intervention pertaining to modification of the equipment / hand tool like handle design, easy manoeuvrability, avoiding hand-holding of weight etc. have been proposed

Modelling job rotation in manufacturing systems with aged workers

The increasing trend of retirement age in Europe represents a critical phenomenon for manufacturing and material handling activities, where repetitive activities, involving the handling of different loads at various frequencies, are usually required. These tasks can lead to occupational diseases and work-related musculoskeletal disorders, which can affect more heavily older workers, due to their decreased functional and physical capacities. On the other side, older workers positively contribute to the manufacturing processes through their expertise and their skills developed over time. This paper introduces a bi-objective mathematical model useful to assign different workers exposed to the risk of repetitive work to various workstations. A person-job fit approach is proposed, which analyses the workers’ physical capacities, competencies and mental and relational skills together with the requirements of each workstation in terms of capabilities and ergonomic load. The aim is to define the activities scheduling through two objectives: the first one considering the matches among workers abilities and workstations activities, the second one reducing the ergonomic risk of repetitive work by varying the assignments during the work shift. The method is also applied to an industrial case, whose results show its applicability and potential benefits, in terms of ergonomics and overall efficiency improvement.

Building thermal load management through integration of solar assisted absorption and desiccant air conditioning systems: A model-based simulation-optimization approach

Performance of standalone air-conditioning systems is affected while simultaneously handling both sensible and latent building loads. Model-based simulation and optimization is one of the best ways to analyze system's performance under load fluctuations at the initial design stages. Therefore, in the current study, seasonal transient simulations of an Integrated Absorption Desiccant System are carried out using TRNSYS to handle sensible (10.94 kW peak) and latent (4.44 kW peak) cooling load separately. Radiant cooling with chilled water from an absorption chiller mainly handles sensible cooling load, while the latent load is achieved by a solid desiccant dehumidification system. Initially, key components of the system are modeled in TRNSYS including a flat plate solar collector system, desiccant wheel, heat recovery wheel, and absorption chiller. Afterwards, the integrated model is coupled with GenOpt to optimize the solar fraction and thermal coefficient of performance by varying collector area, flow rate in the collector loop, flow rate in load side loop, and volume of storage tank. The resulted optimized value of solar fraction is 57.50%, and COPth is 0.55 for standalone absorption system, whereas the solar fraction of 56.20%, COPth of 1.52 are achieved for IADS. In addition, the effects of load variation in terms of sensible to latent load ratio on regeneration heat required for both IADS and conventional desiccant system are also analyzed. A critical value of load ratio of 0.75 is also observed in terms of heat regeneration requirements to compare the both systems. The proposed approach and analysis will be very helpful for HVAC designers for optimal system performance through separate load handling, especially at the initial design stage.

Three Gorges Project: benefits and challenges for shipping development in the upper Yangtze River

ABSTRACT The Three Gorges Project has benefited shipping development in the upper Yangtze River by improving the waterway channel and thus increasing ship load and port handling capacity. However, the Three Gorges lockage freight volume exceeded the designed capacity in 2011 (19 years sooner than expected), becoming a bottleneck for shipping development. For the predicted freight volume, building of a second ship lock with transit capacity of 150 million tons is suggested, and before it is built, ship organization should be optimized to increase transit capacity.

Ergonomic intervention to reduce musculoskeletal disorders among flour factory workers

Work-related musculoskeletal disorders are the most common occupational health hazards. In the flour production industry, the fast pace of work, high frequency of repetitive movements, manual handling of loads, and awkward postures put a lot of pressure on the worker's body. Given the high exposure of the workers of the flour production industry to ergonomic risk factors, this study aimed to reduce the rate of musculoskeletal disorders among a group of flour factory workers through ergonomic interventions. This interventional study was performed using the census method on the eligible workers of a flour factory. An ergonomic intervention program was planned and implemented with the goal of reducing musculoskeletal disorders. The effectiveness of the program was evaluated by measuring the prevalence of musculoskeletal disorders before and six months after the interventions. Before the intervention, musculoskeletal disorders were most prevalent in the lower back, arms, shoulders, legs, thighs, knees, neck and wrists, respectively. Evaluation of the prevalence of musculoskeletal disorders after the intervention showed the positive effect of the ergonomic intervention program on musculoskeletal disorders in the neck, shoulders, lower back, thighs, knees, and legs (P < 0.05). Engineering and management interventions implemented in this study led to a significant reduction in the level of ergonomic risk factors and a reduced rate of musculoskeletal disorders among workers of different units in the flour factory.

Ergolean: quando ergonomia e lean manufacturing integrano il management e la sicurezza aziendale

The prevention of musculoskeletal disorders (MSDs)is defined in accordance with specific European Union directives, enforced in Italy with Legislative Decree 81/2008.Ergonomic conditions of the workplace are considered, inorder to properly assess risks, from the planning of activities and work tasks related to human beings. To combatMSDs, companies should apply the principles of ergonomics, together with the satisfaction of customer needs, ina Total Quality Management logic (TQM).Lean Manufacturing aims to increase production but at the same time toreduce waste. The proposed case shows that Ergonomics and Lean Manufacturing, if well integrated, can representan opportunity for the entire organisation, putting the worker at the centre of improvement. The objective of the caseis the study of workstations in a Company in the wood sector located in the Marche Region. The aim is to reduce riskindices resulting from manual handling of loads and repetitive movements, with reference to mandatory and voluntarysafety regulations. Therefore, demonstrating that, by decreasing risk factors indices, production down-time can bereduced, and production levels increased. As a result of the analysis of the production line, ergonomically inadequateworkstations have been modified, but productivity requirements have not been neglected. For the prevention to beeffective on an ongoing basis, it requires the participation and the collaboration of various professionals with thecommon objective of leading companies to improved productive performances but, without neglecting the health andsafety of their workers.

Ergolean: quando ergonomia e lean manufacturing integrano il management e la sicurezza aziendale

The prevention of musculoskeletal disorders (MSDs)is defined in accordance with specific European Union directives, enforced in Italy with Legislative Decree 81/2008.Ergonomic conditions of the workplace are considered, in order to properly assess risks, from the planning of activities and work tasks related to human beings. To combat MSDs, companies should apply the principles of ergonomics, together with the satisfaction of customer needs, in a Total Quality Management logic (TQM).Lean Manufacturing aims to increase production but at the same time to reduce waste. The proposed case shows that Ergonomics and Lean Manufacturing, if well integrated, can represent an opportunity for the entire organisation, putting the worker at the centre of improvement. The objective of the case is the study of workstations in a Company in the wood sector located in the Marche Region. The aim is to reduce risk indices resulting from manual handling of loads and repetitive movements, with reference to mandatory and voluntary safety regulations. Therefore, demonstrating that, by decreasing risk factors indices, production down-time can be reduced, and production levels increased. As a result of the analysis of the production line, ergonomically inadequate workstations have been modified, but productivity requirements have not been neglected. For the prevention to be effective on an ongoing basis, it requires the participation and the collaboration of various professionals with the common objective of leading companies to improved productive performances but, without neglecting the health and safety of their workers.

Forklift truck performance simulation and fuel consumption estimation

PurposeForklift trucks are generally operated with frequent accelerations and stops, reverse and operations of load handling. This way of operation increases the energy losses and consequently the need for reduction of fuel consumption from forklift customers. This study aims to build a model to replicate the performance of forklifts during real operations and estimate fuel consumption without building a real prototype.Design/methodology/approachAVL Cruise has been used to simulate forklift powertrain and hydraulic circuit. The driving cycles used for this study were in accordance with the standard VDI 2198. Artificial neural networks (ANNs), trained by the results of AVL Cruise simulations, have been used to forecast the fuel consumption for a large set of possible driving cycles.FindingsThe comparison between simulated and experimental data verified that AVL Cruise model was able to simulate the performance of real forklifts, but the results were only valid for the specified driving cycle. The ANNs, trained by the results of AVL Cruise for a certain number of driving cycles, have been found effective to forecast the fuel consumption of a larger number of driving cycles following the prescriptions of the standard VDI 2198.Originality/valueA new method based on ANN, trained by AVL Cruise simulation results, has been introduced to forecast the forklift fuel consumption, reducing the computational time and the cost of experimental tests.

Heavy Object Lifting Platform to Correct Human Balance and Posture

This research document on technological development is aimed at workers in small companies, those that are developing well and soon to emerge as companies that will be positioned at the top of their labor sector. Starting from the problem at present with respect to the bad manipulation of loads it is arranged to solve the problem with established objectives to try to correct the corporal posture at the time of lifting an object with a machine that replaces the functions of the worker. The design and the solution was made based on the requirements of the worker, workers who have the need to load objects at a certain height, here the man-machine relationship, demands and desires that help to achieve the general objective are analyzed. In addition, it has the main function of this machine: to lift heavy objects of up to 150 kg of mass, this due to the implementation of a hydraulic piston in the lifting platform. The appropriate solution is an adaptation of a platform in the form of a truck forming an angle of 47.17 between the structure of the truck and the horizontal surface, this position is the most adequate so that the back does not suffer injuries during the handling of loads at work. The results give assurance that it is a machine of reliability and easy handling since it only requires an operator to control the objects and a flat position on the back without damaging the spine.

Risk Analysis in a Tropical Forest Wood Exploration and Processing System in Mato Grosso State, Brazil

Forestry and logging activities in tropical regions are commonly carried out in inappropriate thermal conditions, due to the hot and humid climate, demanding from the worker high energy expenditure and physical effort. They often operate and handle machines and equipment that produce high levels of noise and vibration, and adopt postures that can be harmful to the body, given the constant lifting, handling and transport of loads above tolerable limits. The objective of this study was to evaluate the exposure of workers to risks in a rainforest harvesting and processing system in northern Mato Grosso State, Brazil. The study was conducted in two forest management areas and four processing industries. Occupational heat exposure was assessed and a qualitative analysis of noise and vibration was performed in the two study areas. Occupational exposure to heat was performed by determining the Wet Bulb Index and Globe Thermometer (IBUTG), while the qualitative analysis of noise and vibration was performed with the application of a Risk Analysis methodology. The results indicate that the values of the wet bulb index and globe thermometer (IBUTG), obtained every hour of the working day in the activities of the timber industry and wood processing, correspond to values above the tolerance limit, as standardized. The condition most likely to be harmful to health was found in the exposure to noise by workers in the wood processing industry, especially in operations related to the logging stages, where the risk was categorized as intolerable. With respect to exposure to vibration, the risk was higher in chainsaw operations in logging. In this case, it was possible to qualitatively analyze which occupational exposure limit (OEL) would be exceeded when the machine was in operation, representing risks to workers’ health and safety. It is concluded that there is a need to adopt control measures, since the risk exposure levels were in a range that poses a risk to workers’ health.

The value of force and torque measurements in transanal total mesorectal excision (TaTME)

BackgroundTransanal total mesorectal excision (TaTME) is associated with a relatively long learning curve. Force, motion, and time parameters are increasingly used for objective assessment of skills to enhance laparoscopic training efficacy. The aim of this study was to identify relevant metrics for accurate skill assessment in more complex transanal purse-string suturing.MethodsA box trainer was designed for TaTME and equipped with two custom made multi-DOF force/torque sensors. These sensors measured the applied forces in the axial direction of the instruments (Fz), instrument load orientation expressed in torque (Mx and My) on the entrance port, and the full tissue interaction force (Fft) at the intestine fixation point. In a construct validity study, novices for TaTME performed a purse-string suture to investigate which parameters can be used best to identify meaningful events during tissue manipulation and instrument handling.ResultsSignificant differences exist between pre- and post-training assessment for the mean axial force at the entrance port Fz (p = 0.01), mean torque in the entrance port Mx (p = 0.03) and mean force on the intestine during suturing Fft (p = 0.05). Furthermore, force levels during suturing exceed safety threshold values, potentially leading to dangerous complications such as rupture of the rectum.ConclusionsForces and torque measured at the entrance port, and the tissue interaction force signatures provide detailed insight into instrument handling, instrument loading, and tissue handling during purse-string suturing in a TaTME training setup. This newly developed training setup for single-port laparoscopy that enables objective feedback has the potential to enhance surgical training in TaTME.

Multi-connection load compensation and load information calculation for an upper-limb exoskeleton based on a six-axis force/torque sensor

In this article, a method of multi-connection load compensation and load information calculation for an upper-limb exoskeleton is proposed based on a six-axis force/torque sensor installed between the exoskeleton and the end effector. The proposed load compensation method uses a mounted sensor to measure the force and torque between the exoskeleton and load of different connections and adds a compensator to the controller to compensate the component caused by the load in the human–robot interaction force, so that the human–robot interaction force is only used to operate the exoskeleton. Therefore, the operator can manipulate the exoskeleton with the same interaction force to lift loads of different weights with a passive or fixed connection, and the human–robot interaction force is minimized. Moreover, the proposed load information calculation method can calculate the weight of the load and the position of its center of gravity relative to the exoskeleton and end effector accurately, which is necessary for acquiring the upper-limb exoskeleton center of gravity and stability control of whole-body exoskeleton. In order to verify the effectiveness of the proposed method, we performed load handling and operational stability experiments. The experimental results showed that the proposed method realized the expected function.

Wavelength-agile and radio-agile FiWi access network using dynamic scheduling to improve upstream delay and resource utilization

Fiber wireless (FiWi) access network which is also referred as hybrid wireless optical broadband access network is one of the modern architecture to solve the problem of bandwidth availability and flexibility simultaneously. It integrates wireless frontend with optical backend. In FiWi network most of component remains idle for large duration, hence efficiency is very crucial. To improve energy efficiency in FiWi many multiple access (MA) techniques had been implemented at backend. However inclusion of multiple access techniques usually incur problem of delay, as data transfer in such network takes place only in the assigned slot of access technique. In this paper a novel architecture is proposed for FiWi which implements wavelength agile hybrid multiple access at backend and radio agile access technique at frontend. Further to improve delay performance, bandwidth availability and utilization of resources; a new scheduling approach is proposed for multiple access techniques implemented at frontend as well as backend. Delay performance, wavelength availability and load handling capacity of proposed approach is compared with different hybrid multiple access architecture. To best of our knowledge, wavelength agile and radio agile MA has been used for the first time in FiWi, moreover the proposed scheduling approach implemented on MA provide promising results in terms of delay and resource utilization. The performance of proposed work is also evaluated in terms of service and reservation delay component to indicate its utility in terms of actual information content per frame. The result shows effectiveness of proposed architecture over other existing architectures.

A MIN-MAX SCHEDULING LOAD BALANCED APPROACH TO ENHANCE ENERGY EFFICIENCY AND PERFORMANCE OF MOBILE ADHOC NETWORKS

Energy efficiency and traffic management in Mobile Ad hoc Networks (MANETs) is a complex process due to the self-organizing nature of the nodes. Quality of service (QoS) of the network is achieved by addressing the issues concerned with load handling and energy conservation. This manuscript proposes a min-max scheduling (M2S) algorithm for energy efficiency and load balancing (LB) in MANETs. The algorithm operates in two phases: neighbor selection and load balancing. In state selection, the transmission of the node is altered based on its energy and packet delivery factor. In the load balancing phase, the selected nodes are induced by queuing and scheduling the process to improve the rate of load dissemination. The different processes are intended to improve the packet delivery factor (PDF) by selecting appropriate node transmission states. The transmission states of the nodes are classified through periodic remaining energy update; the queuing and scheduling process is dynamically adjusted with energy consideration. A weight-based normalized function eases neighbor selection by determining the most precise neighbor that satisfies transmission and energy constraints. The results of the proposed M2SLB (Min-Max Scheduling Load Balancing) proves the consistency of the proposed algorithm by improving the network throughput, packet delivery ratio and minimizing delay and packet loss by retaining higher remaining energy.

Trastornos musculoesqueléticos en trabajadores de la manufactura de neumáticos, análisis del proceso de trabajo y riesgo de la actividad

La morbilidad osteoarticular es uno de los padecimientos más frecuentes a nivel mundial tanto en países industrializados como en vías de desarrollo. El objetivo de este estudio fue evaluar la asociación de las exigencias del proceso de trabajo de manufactura de neumáticos con la presencia de lumbalgia y trastornos musculoesqueléticos. También, se evaluó el riesgo de lesión dorsolumbar en un puesto de trabajo por manejo manual de cargas. Mediante un diseño transversal, se estudiaron a 185 operadores que realizan actividades operativas en una planta de producción y distribución de neumáticos. Se encontró una prevalencia de lumbalgia de 20% y de trastornos musculoesqueléticos en extremidades superiores e inferiores de 30%, que se asoció al manejo manual de cargas. Se encontró un riesgo elevado para el desarrollo de lesión dorsolumbar. Se propone reforzar las medidas que mitiguen o minimicen los daños músculo esqueléticos derivados del proceso técnico.

A Min-Max Scheduling Load Balanced Approach to Enhance Energy Efficiency and Performance of Mobile ADHOC Networks

Energy efficiency and traffic management in Mobile Ad hoc Networks (MANETs) is a complex process due to the self-organizing nature of the nodes. Quality of service (QoS) of the network is achieved by addressing the issues concerned with load handling and energy conservation. This manuscript proposes a min-max scheduling (M2S) algorithm for energy efficiency and load balancing (LB) in MANETs. The algorithm operates in two phases: neighbor selection and load balancing. In state selection, the transmission of the node is altered based on its energy and packet delivery factor. In the load balancing phase, the selected nodes are induced by queuing and scheduling the process to improve the rate of load dissemination. The different processes are intended to improve the packet delivery factor (PDF) by selecting appropriate node transmission states. The transmission states of the nodes are classified through periodic remaining energy update; the queuing and scheduling process is dynamically adjusted with energy consideration. A weight-based normalized function eases neighbor selection by determining the most precise neighbor that satisfies transmission and energy constraints. The results of the proposed M2SLB (Min-Max Scheduling Load Balancing) proves the consistency of the proposed algorithm by improving the network throughput, packet delivery ratio and minimizing delay and packet loss by retaining higher remaining energy.

Simulation and experimental verification of a drop test and compression test of a gable top package

A finite element framework has been proposed that can be used to simulate both empty paperboard packages and package filled with plastic granulates. A gable top package was made of a commercial paperboard, and material properties needed in the material model were determined. Two simulations were performed, a drop test and a compression test. By comparison between experimental and numerical results, the deformation mechanisms at impact could be identified and correlated to material properties. When the package was filled with granulates, different mechanisms was activated compared with an empty package. The granulates contribute to bulging of the panels, such that the edges became more load bearing compared with the panels. When the edges carried the loads, the importance of the out‐of‐plane properties also increased, and local failure initiation related to delamination was observed. Comparison between experimental and numerical impact forces shows that there are still important things to consider in the model generation, eg, variation of properties within the package, which originate both from material property variations, and the loading history, eg, during manufacturing and handling.

Reconfigurable magnetic microrobot swarm: Multimode transformation, locomotion, and manipulation.

Swimming microrobots that are energized by external magnetic fields exhibit a variety of intriguing collective behaviors, ranging from dynamic self-organization to coherent motion; however, achieving multiple, desired collective modes within one colloidal system to emulate high environmental adaptability and enhanced tasking capabilities of natural swarms is challenging. Here, we present a strategy that uses alternating magnetic fields to program hematite colloidal particles into liquid, chain, vortex, and ribbon-like microrobotic swarms and enables fast and reversible transformations between them. The chain is characterized by passing through confined narrow channels, and the herring school-like ribbon procession is capable of large-area synchronized manipulation, whereas the colony-like vortex can aggregate at a high density toward coordinated handling of heavy loads. Using the developed discrete particle simulation methods, we investigated generation mechanisms of these four swarms, as well as the "tank-treading" motion of the chain and vortex merging. In addition, the swarms can be programmed to steer in any direction with excellent maneuverability, and the vortex's chirality can be rapidly switched with high pattern stability. This reconfigurable microrobot swarm can provide versatile collective modes to address environmental variations or multitasking requirements; it has potential to investigate fundamentals in living systems and to serve as a functional bio-microrobot system for biomedicine.

Ship-to-Ship State Observer Using Sensor Fusion and the Extended Kalman Filter

In this paper, a solution for estimating the relative position and orientation between two ships in six degrees-of-freedom (6DOF) using sensor fusion and an extended Kalman filter (EKF) approach is presented. Two different sensor types, based on time-of-flight and inertial measurement principles, were combined to create a reliable and redundant estimate of the relative motion between the ships. An accurate and reliable relative motion estimate is expected to be a key enabler for future ship-to-ship operations, such as autonomous load transfer and handling. The proposed sensor fusion algorithm was tested with real sensors (two motion reference units (MRS) and a laser tracker) and an experimental setup consisting of two Stewart platforms in the Norwegian Motion Laboratory, which represents an approximate scale of 1:10 when compared to real-life ship-to-ship operations.