Search

In order to solve the problems of complex processes, long cycle, high cost and high risk in traditional installation methods of large floating crane jibs, a novel prevent failure method using a gantry crane to install the floating crane jib is proposed and key technologies, such as reasonable solution for distributing force on the lifting point in the jib lifting through adopting balanced suspensory rigging, efficient shaft threading technology with guide and traction device and newly developed compliant support structure against ship rolling. In this article, we present the application cases of systematic installation method of the large floating crane jib to real production process. The engineering practice proves that the novel installation method proposed is simple in operation and low in cost and provides a new and reliable choice for the installation and maintenance of large floating crane. [ABSTRACT FROM AUTHOR]

The gantry crane, positioned atop the bridge pier cap for the installation of Super-T girders, is a specialized construction unit within the bridge construction industry. The article presents a summary of research results investigating dynamic parameters and their influence on the operation of gantry cranes with assembled structures on the cap of bridge piers, serving the installation of Super-T beams in two scenarios: lifting with pre-stressed cable and moving with load (Super-T beam). To examine the dynamic parameters affecting the operation of the gantry crane, the authors first constructed a dynamic model. Subsequently, the influential parameters were determined, and the Matlab Simulink software was employed to develop a survey model corresponding to different values of each parameter and under various working conditions of the gantry crane. This process aimed to identify patterns and unfavorable values of these parameters affecting the operation of the gantry crane. The research results revealed that in both scenarios of lifting with pre-stressed cable and moving with a load (loading), factors such as lifting speed (Vn), stiffness of the main steel structure (S3), conversion stiffness of the lifting cable (S1), oscillation mass of the main structure (m3), wind load acting on the beam (Pg2), wind load acting on the main steel structure (Pg1), and stiffness of the hanging cable (S1) significantly influence the operation of the gantry crane. The survey results also indicated reasonable values for these influential factors during the operation of the gantry crane. The obtained research results can serve as a basis for computational design problems and effective utilization of gantry cranes with assembled structures on the cap of bridge piers for the installation of Super-T beams. Through analysis and simulation using Matlab-Simulink software, specific data on cable tension, main structure acceleration, and structural deformation were collected. The results emphasize the importance of limiting the lifting speed to 2 m/min to ensure stability during cable tensioned lifting and restricting the crane's moving speed to 7.85 m/min to maintain safety and performance when moving loads with tensioned cables. [ABSTRACT FROM AUTHOR]

Building in the river: major maintenance of the Kachlet weir system after 100 years of operation The Kachlet weir system is one of the largest weir systems on the German Rhine‐Main‐Danube waterway and is reaching a 100‐year service life. In order to ensure the continued navigability of the Danube, a major overhaul will be carried out in which the weir base will be preserved, the piers upgraded and the weir superstructure and hydraulic steelwork as well as the technical equipment completely renewed. New approaches are being considered for this particular challenge, especially in terms of construction logistics. As a construction aid for the planned construction project, a portal crane system will be erected above the weir system, which will enable the project to be carried out with a high degree of prefabrication and, as a result, a comparatively short construction period. However, the portal crane system also brings new challenges with it, that need to be taken into account during planning. [ABSTRACT FROM AUTHOR]

In order to address stringent standards, energy efficiency objectives or also cost reduction imperatives, the optimal design of complex industrial structures is an important concern. In this context, parametric optimization offers a powerful tool for engineers. Taking into account nonlinear behavior in the models allows performing high-fidelity numerical simulations and thus reducing safety margins. However, in vibration dynamics, the use of classical global optimization methods on industrial-scale structures with nonlinearities is not affordable due to too many required solver calls to localize the optimum. This work proposes an approach to achieve global constrained optimization of structures with local nonlinearities in vibration. The strategy is based on a Bayesian Optimization process relying on two tools: (i) a Gaussian Process as a surrogate model and (ii) a dedicated nonlinear mechanical solver based on the Harmonic Balance Method. These two tools are presented in detail. Their performance and characteristics are presented and analyzed on academic and industrial-scale examples. The whole strategy is finally applied on a Duffing oscillator without optimization's constraint and a gantry crane to illustrate the efficiency on constrained optimization. In addition, many discussions are made relative to the number of initial sample points. The results show that the proposed approach is able to find the global optimum with a limited number of solver calls, demonstrating its ability to be integrated into an actual industrial design process. [ABSTRACT FROM AUTHOR]

Purpose: In this article, the feedback control and stabilization problem of dual PMLSM-driven H-type gantry cranes is treated with the use of a flatness-based control method which is implemented in successive loops. Dual-drive gantry cranes can achieve high torque and high precision in the tasks' execution. Such a type of crane can be used in several industrial applications. The solution to the associated nonlinear control problem is a particularly challenging research objective. Methods: The integrated system that comprises the H-type gantry crane and two PMLSMs is shown to be differentially flat. The control problem for this robotic system is solved with the use of a flatness-based control approach which is implemented in successive loops. To apply the multi-loop flatness-based control scheme, the state-space model of the H-type gantry crane with dual PMLSM is separated into subsystems, which are connected in cascading loops. Results: For each subsystem, control can be performed with inversion of its dynamics as in the case of input–output linearized flat systems. The state variables of the preceding (ith) subsystem become virtual control inputs for the subsequent (i+1)th subsystem. In turn, exogenous control inputs are applied to the last subsystem. The whole control method is implemented in successive loops and its global stability properties are also proven through Lyapunov stability analysis. Conclusion: A novel nonlinear optimal control method has been developed for the dynamic model of a dual PMLSM-driven gantry crane. The proposed method achieves stabilization of the H-type gantry crane with dual PMLSM without the need for diffeomorphisms and complicated state-space model transformations. Using the local differential flatness properties of each one of the subsystems that constitute the gantry crane's model, the design of a stabilizing feedback controller is enabled. [ABSTRACT FROM AUTHOR]

Summary: In this paper, a robust adaptive vibration control method for gantry crane system is proposed considering unknown parameters brought by unknown payload, cable length and tension. The control objective is to transport the cargo to the desired position while suppressing the vibration of the cable in the presence of unknown parameters. For this purpose, a boundary controller is designed with an adaptive law to compensate the parameter uncertainty of the system. The well‐posedness of the closed‐loop system is proved by means of operator semigroup theory and the asymptotic stability of the closed‐loop system is analyzed. Finally, the effectiveness of the proposed control approach is demonstrated through both numerical simulation comparisons and physical experiments. [ABSTRACT FROM AUTHOR]

In view of bottlenecks encountered in the process of turnout laying and replacement on high-speed railways such as substantial construction difficulties, low efficiency, intensive labor workload, and high risk, this paper proposes a control method of intelligent turnout laying and replacement equipment with combined gantry cranes for high-speed railways. It is proposed to utilize a control strategy of asynchronous transverse movement and synchronous tilting of the combined gantry cranes to handle the rotation and longitudinal motion of large components respectively. A theoretical mathematical modeling analysis is performed for the turnout laying and replacement equipment with combined gantry cranes focusing on the rotation and longitudinal movement operations. Moreover, considering the flexible nature of chains in the real construction process of combined gantry cranes, a self-learning algorithm is incorporated to facilitate flexible and highly precise multi-crane cooperative micro-motion control. The experimental results from field operations showcases adopting the control method proposed in this article, stable and reliable rotation and longitudinal movement by the combined gantry cranes, with an operational error of less than 10 mm, achieving full compliance with the requirements of engineering applications demonstrates.

The present paper concerns the problem of estimating the loading induced by the wind on a gantry crane standing in the open air. Sufficiently strong wind may cause the device to move or even tip over. Two different structures were studied, namely the box girder and truss girder. At the very beginning, the two sectional scaled parts of the main horizontal beam (box and truss girder) of the gantry were prepared. Next, experimental analysis using these models was carried out in an aerodynamic tunnel to estimate the horizontal forces induced by the airflow acting on them. The experimental values of the aerodynamic forces were exploited to verify the 3D computational model of the studied structure. Numerical computations were carried out using the ANSYS Fluent 2022R2 system for both sectional models of the gantry crane mentioned above. The standard k-epsilon model of the turbulent flow of the air is employed. Satisfactory agreement of the values between the experimental and numerical results was achieved. As a result of the performed computations, the magnitude of the critical wind velocity that can be dangerous for the studied gantry cranes was estimated. Finally, a model of the gantry crane with box girder at full scale was analyzed using CFD simulations for different Davenport wind profiles. The results obtained from the experimental and numerical analysis of the sectional models were compared with the appropriate standards. In the current work, attention is drawn to the importance of changing wind direction in the vertical plane since, as shown in the results of this work, even a small change in vertical angle, up to 6°, causes significant changes in the value of the force required to overturn the gantry crane. [ABSTRACT FROM AUTHOR]

Gantry cranes play a pivotal role in various industrial applications, and their reliable operation is paramount. While routine inspections are standard practice, certain defects, particularly in less accessible components, remain challenging to detect early. In this study, first a finite element model is presented, and the damage is introduced using random changes in the stiffness of different parts of the structure. Contrary to the assumption of inherent reliability, undetected defects in crucial structural elements can lead to catastrophic failures. Then, the vibration equations of healthy and damaged models are analyzed to find the displacement, velocity, and acceleration of the different crane parts. The learning vector quantization neural network is used to train and detect the defects. The output is the location of the damage and the damage severity. Noisy data are then used to evaluate the network performance robustness. This research also addresses the limitations of traditional inspection methods, providing early detection and classification of defects in gantry cranes. The study's relevance lies in the need for a comprehensive and efficient damage detection method, especially for components not easily accessible during routine inspections. [ABSTRACT FROM AUTHOR]

Container terminal yards are automated terminal yards. The rail-mounted gantry crane (RMGC) and rail-mounted gantry crane tracks (RMGCTs) that frequently operate in terminal yards need to be inspected regularly to ensure the safe operation of container transportation in the yard. This paper proposes a framework for the path planning of RMGCT visual inspection using a UAV in container terminal yards in a port environment. The framework consisted of two main aspects. First, a global path to all inspection viewpoints was planned according to the inspection requirements using the A* algorithm and the improved minimum snap method. Second, the intelligent bidirectional rapidly exploring random trees star (IB-RRT*) algorithm was introduced to plan the local path during the flight of the UAV. Finally, the feasibility of the path-planning framework was demonstrated using simulation experiments. [ABSTRACT FROM AUTHOR]

Conventionally, researchers have favored the model-based control scheme for controlling gantry crane systems. However, this method necessitates a substantial investment of time and resources in order to develop an accurate mathematical model of the complex crane system. Recognizing this challenge, the current paper introduces a novel data-driven control scheme that relies exclusively on input and output data. Undertaking a couple of modifications to the conventional marine predators algorithm (MPA), random average marine predators algorithm (RAMPA) with tunable adaptive coefficient to control the step size (CF) has been proposed in this paper as an enhanced alternative towards fine-tuning data-driven multiple-node hormone regulation neuroendocrine-PID (MnHR-NEPID) controller parameters for the multi-input–multi-output (MIMO) gantry crane system. First modification involved a random average location calculation within the algorithm's updating mechanism to solve the local optima issue. The second modification then introduced tunable CF that enhanced search capacity by enabling users' resilience towards attaining an offsetting level of exploration and exploitation phases. Effectiveness of the proposed method is evaluated based on the convergence curve and statistical analysis of the fitness function, the total norms of error and input, Wilcoxon's rank test, time response analysis, and robustness analysis under the influence of external disturbance. Comparative findings alongside other existing metaheuristic-based algorithms confirmed excellence of the proposed method through its superior performance against the conventional MPA, particle swarm optimization (PSO), grey wolf optimizer (GWO), moth-flame optimization (MFO), multi-verse optimizer (MVO), sine-cosine algorithm (SCA), salp-swarm algorithm (SSA), slime mould algorithm (SMA), flow direction algorithm (FDA), and the formally published adaptive safe experimentation dynamics (ASED)-based methods. [ABSTRACT FROM AUTHOR]

The port container gantry crane studied in this paper is a four-degree-of-freedom spatial continuous system. In actual work, in order to make the container transfer smoothly, the response of the whole system needs to be accurately predicted and timely adjusted. The whole system is divided into rotary mechanism, lifting mechanism, lifting trolley mechanism, and big cart mechanism for detailed analysis. By constructing the field transfer matrix, a one-dimensional wave equation of continuous system and the Lagrange equation with redundant parameters, the response of each subsystem is solved precisely. The results of the study found that in some periods, the swing of the container was too large. In order to improve the safety and stability of transmission, an active control method of specific point in time excitation (SPE) is proposed for the first time. This method predicts the swing amplitude of the container in advance using the response results of the numerical model. When the set response interval is exceeded, the external excitation intervention can effectively inhibit the moving range of the container in the transit process. Finally, the results are compared with the simulation model to achieve the experimental purpose. It is in line with the expected experimental effect. [ABSTRACT FROM AUTHOR]

Due to their unique structural design, portal cranes have been extensively utilized in bulk cargo and container terminals. The bearing fault of their drive motors is a critical issue that significantly impacts their operational efficiency. Moreover, the problem of imbalanced fault samples has a more pronounced influence on the application of novel fault diagnosis methods. To address this, the paper presents a new method called bidirectional gated recurrent domain adversarial transfer learning (BRDATL), specifically designed for imbalanced samples from portal cranes' drive motor bearings. Initially, a bidirectional gated recurrent unit (Bi-GRU) is used as a feature extractor within the network to comprehensively extract features from both source and target domains. Building on this, a new Correlation Maximum Mean Discrepancy (CAMMD) method, integrating both Correlation Alignment (CORAL) and Maximum Mean Discrepancy (MMD), is proposed to guide the feature generator in providing domain-invariant features. Considering the real-time data characteristics of portal crane drive motor bearings, we adjusted the CWRU and XJTU-SY bearing datasets and conducted comparative experiments. The experimental results show that the accuracy of the proposed method is up to 99.5%, which is obviously higher than other methods. The presented fault diagnosis model provides a practical and theoretical framework for diagnosing faults in portal cranes' field operation environments. [ABSTRACT FROM AUTHOR]

The global supply chain depends on the efficient transfer of containers between cargo ships and ground transport. To ensure reliable operations, equipment at ports requires predictive maintenance, with minimal downtime, at scheduled times. One common piece of equipment, rail mounted automated gantry (RMG) automatic stacking cranes (ASC), can be outfitted with commodity acceleration sensors to better monitor the structural health of the crane and the rails on which the crane runs. The ratio of the rolling standard deviation of the crane vibration at speed versus at rest is a metric that can separate the cranes and rails into those that are in need of detailed inspection and repair, and those that are in good health. This method produced zero false negative, and an even split of true positives and false positives. The cost of a false positive is orders of magnitude less than the cost of a false negative, so this technique should help bend the cost curve down on RMG maintenance. Industrial RMG ASCs and the rails on which they run are difficult and expensive to survey, but abnormalities can cause damage to the cranes that will be much more expensive and difficult to fix. We are developing a method using low cost computing in the form of Raspberry Pis and commodity acceleration sensors to detect abnormalities without disturbing the use of the crane for a survey. One limitation of low cost sensors is that they produce a signal with a relatively high amount of noise. However, the signal is usable. We quantify the noise level as the rolling standard deviation (RSD) of the raw signal from the smoothed signal, which can be calculated for the crane at rest and at different speeds. The ratio of resting RSD to moving RSD is used to classify a rail as needing attention or as nominal. That ratio can be compared between two cranes that are operating on the same set of rails to determine whether the abnormalities are caused by the crane or by the rail. Utilizing this metric to prioritize track repairs such as tamping or grinding, or crane repairs such as wheel replacement or bogie alignments can significantly reduce the maintenance cost for the overall crane systems. [ABSTRACT FROM AUTHOR]

The heavy congestion at the global ports and the impact of the pandemic spread make the automated container terminal competitive. With the operations of more and more automated container terminals, the optimization of yard space allocation becomes one of the most urgent issues for improving the handling efficiency for the automated container terminal. To figure out the optimal clustering strategy to allocate the containers in the automated container terminal, this study investigates the stacks allocation with different scenarios. A novel stack-based allocation model is built to balance both the transportation distance and the allocation dispersion among blocks. Based on the model we built, we talked about the impact of efficiency of automated rail-mounted gantry crane and the berthing time for each vessel on the stacks allocation. The results show that the stack-based allocation with multi-batches in the same bay is suitable for the automated container terminal, while both the efficiency of the automated rail-mounted gantry crane and the berthing time will directly affect the total transportation distance for allocating the containers. The research is very inspiring for the terminal manager to choose the suitable clustering strategy and improve the yard space management for the automated container terminal. [ABSTRACT FROM AUTHOR]

In this paper, we consider the gantry crane scheduling problem at a single storage block where a total of m gantry cranes are mounted on double tracks so that cranes on different tracks can pass each other while those on the same track cannot. Containers at the storage block are divided into bays and each bay of containers has to be loaded/unloaded together due to the same shipping destination or the same customer. To minimize the overall loading/ unloading time of containers, we first formulate the problem to a mixed integer linear programming (MILP) model, and compute the optimal solutions of small instances by the Gurobi solver. Then we design several heuristic algorithms and test their efficiency and performance by a series of large instances. In particular, we present a polynomial time approximation algorithm for the case where all but one gantry crane is mounted on the same track. We show that the algorithm has a worst case ratio of 2 − 2 m , outperforming the partition-based algorithms in the single-track scenario. [ABSTRACT FROM AUTHOR]

A sea-rail automated container terminal (SRACT) plays a crucial role in the global logistics network, combining the benefits of sea and railway transportation. However, addressing the challenges of multi-equipment cooperative scheduling in terminal and railway operation areas is essential to ensure efficient container transportation. For the first time, this study addresses the cooperative scheduling challenges among railway gantry cranes, yard cranes, and automated guided vehicles (AGVs) under the loading and unloading mode in SRACTs, ensuring efficient container transportation. This requires the development of a practical scheduling model and algorithm. In this study, a mixed integer programming model was established for the first time to study the multi-equipment cooperative scheduling problem of a SRACT under the loading and unloading mode. A self-adaptive chaotic genetic algorithm was designed to solve the model, and the practicability and effectiveness of the model and algorithm were verified by simulation experiments. Furthermore, this study also proposes an AGV number adjustment strategy to accommodate changes in vessel arrival delays and train container types. Simulation experiments demonstrated that this strategy significantly reduces loading and unloading time, decreases equipment energy consumption, and improves the utilization rate of AGVs. This research provides valuable guidance for ongoing SRACT projects and advances and methodological approaches in multi-equipment co-operative scheduling for such terminals. [ABSTRACT FROM AUTHOR]

With the gradual improvement of market demand and the continuous improvement of equipment manufacturing, the demand for the use of large-section, large-scale, and large-scale structural wharf at home and abroad is increasing. Therefore, the difficulty of wharf construction has also increased accordingly, and the installation of prefabricated components requires construction equipment with more prominent lifting capacity and better construction techniques. This paper mainly introduces the key technologies for the installation and construction of prefabricated components for the ultra-wide wharf of the Wilmar Industrial Park Port Project in Banten Indonesia. The overall widest part of the hydraulic structure of this project reaches 70 m. This technology utilizes a 70 t special portal crane and a set of 250 t+5 000 t square barge crane unit for combined installation, and cooperates with the multi-functional hoisting frame to install the wharf beam and slab. The successful application of this technology in the water installation of prefabricated components similar to ultra -wide high -piled wharves has important reference significance for improving construction efficiency, ensuring structural safety, and reducing equipment costs. [ABSTRACT FROM AUTHOR]

We study the operational problem of loading and unloading trains at a container terminal. Trains are served by two gantry cranes which spread over multiple trains on parallel tracks at the terminal landside. Multiple straddle carriers are available to move containers between the stacking area and drop off locations perpendicular to the train tracks. The trains must be loaded and unloaded with given departure times. We develop a mixed-integer programming model to schedule the gantry cranes and straddle carriers to load and unload the trains. The objective is to minimize the total delay of trains. Due to the complexity involved, the problem is solved using a simulated annealing heuristic. We perform extensive numerical experiments to analyze the impact of different variables and parameters on minimizing the total delay. More specifically, the impact of three variables including the number of trains, containers on trains, and available straddle carriers are evaluated. [ABSTRACT FROM AUTHOR]

Assessment of dynamic behavior of the gantry cranes by using mathematical modeling and shaking table tests is the subject of this study. In this context, the study was carried out in two stages through theoretical and experimental studies. In the theoretical study, a four degrees-of-freedom nonlinear mathematical model which represents the seismic behavior of gantry cranes was developed. In the experimental study, a 1/50 scaled crane model of a prototype crane with respect to dynamic equivalence principle was designed and constructed. Within the scope of theoretical and experimental study, the real earthquake and sine sweep motions were used as input data. To verify the mathematical model, the results of the experimental study were used. Comparison of the mathematical model with the experimental study for the gantry crane structure showed reasonable results. This study shows that dynamic analysis can be done with mathematical modeling of this kind of cranes theoretically. In this way, the dynamic analysis required for a crane which is still in the design phase will be made in a short time and it will be possible to apply the necessary changes and see their effects. [ABSTRACT FROM AUTHOR]

It is an important engineering safety problem to control the swing of the suspended objects of container gantry crane. As an important construction machinery for logistics transportation and handling, it is widely used in port container yards. However, due to the flexible characteristics of the wire rope and the heavy working level of the crane container, there will be a large swing during the transportation process, resulting in cargo collision and uncertain load, resulting in cargo damage and casualties. In this paper, a dynamic model of container gantry crane is established according to Lagrange dynamics equation and the controllability of the system is verified. A hierarchical sliding mode controller (HSMC) is designed, and its stability is proved by using Lyapunov theory and Barbalat's lemma. The simulation results show that the controller has high displacement tracking accuracy, can suppress the container swing Angle and attitude pitch Angle in a short time and has strong robustness and stability for the variable system with different parameters. In addition, a platform is built to verify the reliability of the method. [ABSTRACT FROM AUTHOR]

A timely damage state assessment of gantry cranes has a significant impact on the post-earthquake reconstruction and economic recovery in earthquake-stricken areas. This study aims to propose a methodology to rapidly predict the seismic damage states in light of nine classification-based machine learning methods. The 48 earthquake parameters is presented and of which relative importance and influence on the structural responses of the employed simple gantry crane are examined based on the data set matrix of 2760 (ground motions) ×48 (earthquake parameters). Meanwhile the innovative method is proposed to mitigate the class imbalance problem in the training data. Finally, the proposed method is applied to predict the fragility of a gantry crane subjected to ground motions and the efficiency and accuracy of nine machine learning methods are compared herein. The results demonstrate that the parameter of spectral acceleration Sa at the first self-vibration period of the examined structure is of great significance to predict the accurate damage states. Random Forest, Neural Networks, Logistic Regression, and Support Vector Machine are preferable in all selected machine learning methods hereon. And the predictive fragility curves and the fragility curves computed in FE model are consistent approximately in spite of maximum error of 7.5%. [ABSTRACT FROM AUTHOR]

This paper is concerned with unloading of containers at ports, which are key to international trade. Work on the gantry cranes takes place 50 m above ground level in an operation room with a glass footwell, which causes to arise a psychological bias. We conducted a line-of-sight measurement of gantry crane operators working in such an environment. Based on this data, cognitive bias was defined by our own, and certain characteristics could be found by visualizing the relationship with years of experience. We discuss how this can be used for skill transfer [ABSTRACT FROM AUTHOR]

• A new mathematical model for rubber–tyred gantry cranes is developed considering the elastic structure. • Two advanced sliding mode controls are proposed to validate dynamic model. • Experiment shows the sufficient accuracy and effective application of modeling and control to cranes. A gantry crane holds strict underactuation and elastic multibody structure, and thus faces challenges in control system design. For model–based control, we develop a three–dimensional dynamic model of rubber–tyred gantry cranes considering the distributed mass and bending deformation of gantry. Such modelling hybridises the lumped model of trolley–bridge–payload motions and continuous model of gantry vibration. We consider a complex operation in which three motors composed of travelling trolley, pushing bridge and hoisting container run simultaneously. We propose two versions of the robust controller, namely, dynamic sliding mode and fast terminal sliding mode for tracking the three motions, eliminating swings of container, and reducing the bending vibration of elastic gantry. Simulation and experiment reveal precision and effective application of our crane modelling to control approaches. The control system effectively tracks and stabilises all outputs and achieves robustness when a crane suffers from the structural and parametric uncertainties. [ABSTRACT FROM AUTHOR]

This paper deals with Feedback/Feedforward (FB/FF) control of a gantry crane system intended for the transport of payloads that take values over a known interval. It is also assumed that the crane is affected by unmeasurable disturbances. A new 2DoF control architecture is proposed whose purpose is to speed up the horizontal payload transition while minimizing its oscillations. The main features of the control design procedure are as follows: (1) The output FB controller is designed to ensure robust closed loop stability and steady‐state exact payload positioning; (2) the disturbance is estimated by means of an observer, and its transient effect is compensated through the FF action; and (3) the robust FF control action is given by the optimally weighted sum of the two contributions due to FF Plant Inversion (FFPI) and FF Closed Loop Inversion (FFCLI) control schemes. [ABSTRACT FROM AUTHOR]

This paper presents the research results on the mechanical behavior of the low-carbon rolled steel of a sea portal crane after a 33-year operation depending on the operational stresses and rolling direction in order to assess its serviceability. The tensile properties of steels were investigated using rectangular cross-section specimens with different thicknesses and the same width. Strength indicators were slightly dependent on the considered factors (operational conditions, the cutting direction, and thickness of specimens). However, a clear trend of higher ultimate strength for thinner specimens was noticed, especially in the case of more brittle material due to its operational degradation. Plasticity of the tested steel specimens was more sensitive to the influence of the above-mentioned factors than strength but less sensitive than impact toughness. Uniform elongation was slightly less for thinner specimens regardless of the investigated steel state or the orientation of specimens relative to the rolling direction. The post-necking elongation was lower for transversal specimens compared with longitudinal ones, and the effect was more significant when testing steel with the lowest brittle fracture resistance. Among the tensile properties, non-uniform elongation was demonstrated to be the most effective for assessing the operational changes in the state of rolled steels. [ABSTRACT FROM AUTHOR]

The incidence of fishing boat accidents in Indonesia is very worrying, with 342 people dying during 2018-2020. Based on this, it is crucial to investigate the construction strength of fishing vessels against the possibility of a collision. In this study, the fishing boat due to the impact load was investigated in extreme weather conditions using Finite Element Method (FEM) analysis. Traditional fishing boat was constructed by measuring the thickness of the hull, deck, keel, frames, and longitudinal structure of the fishing boat. The collision model is carried out with an impactor in the form of a mooring pole during extreme weather with a wave height of 6 meters and wind speeds 30 knots. Variations in velocity and frame spacing as in actual conditions are modeled to obtain differences in deformation, absorption energy values, and plasticity of boat construction due to collisions. The collision speed of 30 and 20 knots are set on the extreme weather conditions, while the collision speed of 7 knots is set on operating speed. Frame spacing of 0.5 and 0.6 meters is built according to the boat's frame spacing in the field. Computer simulation is carried out using application software ANSYS Research License. The fishing boat material used is mahogany wood with tested by using impact test with a toughness value of 39.1 kJ/m². Based on the simulations results, the impact velocity has an effect deformation wider crash area and hull stress value. The speed of the ship collision was 7 knots, the collision did not damage the hull, but the construction failed at speeds of 20 and 30 knots. The closer of frame spacing, the higher collision performance of structure to withstand impact are indicated by the higher energy absorption. At a ship collision speed of 30 knots, the absorption energy of the construction at 0.5-meter frame spacing is 49.8 kJ, greater than 0.6-meter frame spacing with a value of 29.6 kJ. [ABSTRACT FROM AUTHOR]

The article deals with the issue concerning the working bodies of technological equipment designed for grinding pieces and particles of feed raw materials. The most profitable feed raw materials are by-products and waste materials of animal origin, which have a valuable high-protein content. An alternative way of mandatory waste disposal is their processing, including mechanical grinding to obtain feed products. In the process of grinding, particular importance is given to the working bodies, with the help of which the raw material is directly divided into parts. In this case, the destruction of the feed material often occurs by means of impact. Impact phenomena have proven to be highly effective in the process of intense cracking and chipping, which leads to the desired separation of the crushed particles into smaller ones. However, it is found that crushers have insufficient efficiency of impact elements. The work analyzes the processes of impact grinding from the standpoint of a number of scientific hypotheses, theories, modeling, simulation, experience and approbation, presented in various scientific publications. When studying and improving the theory of impact, attention is paid to nonlinear problems, cracking, modernization of the theory of brittle fracture, diagrams of force changes during impact force, impact equations, wave theory of impact, peridynamic theory. It should be noted that the main scientific results are directly reflected in the improvement of the design features of hammers. It has been revealed that the main improvement in the design of impact elements is in the direction of increasing the efficiency of working surfaces and developing the combination of impact with cutting, abrasion and crushing. [ABSTRACT FROM AUTHOR]

The article presents briefly findings in researching methods for determining dynamic stress of the bars in the main structure of gantry crane installed on the cap of bridge pier to install and launch SUPER-T girder. In order to study the dynamic stresses in the bars of the main truss structure of the gantry, the author first had to build a dynamic model, using Matlap software to solve the problem of dynamics with two cases cargo lowering combination combines braking and moving of gantry with cargo to find out the rules and values of dynamic cable tension, dynamic inertial force (time-varying force), then consider these forces is the external force acting on the main truss structure model of the gantry, from which the author calculates the value of internal force and stress of each bar corresponding to the value of dynamic cable tension and corresponding dynamic inertia force. with two adverse working cases of the gantry. Using Matlap software to calculate the author has obtained a graph of internal force, stress changes over time of each bar in the main truss steel structure of the gantry. The findings of the research provided methods for determining the dynamic stress of the bars in the main structure of gantry crane, pointed out values and rules of change of the dynamic stress of the bars in the main structure of gantry crane. The findings of the research may be used to calculate fatigue, life-span of the main steel structures as well as other parts of the gantry crane. [ABSTRACT FROM AUTHOR]

Study Design: Retrospective single-arm study. Objective: To propose a novel technique named the gantry crane technique for treating severe thoracic spinal stenosis and myelopathy caused by thoracic ossification of the ligamentum flavum (TOLF) and investigate its clinical results. Methods: From June 2017 to January 2019, 18 patients presenting with severe spinal stenosis and myelopathy caused by TOLF were included in our study. All patients were treated with gantry crane technique, pre-operative JOA score, as well as 3 days-, 3 months-, 6 months-, 12 months-, 24 months after operation, and Hirabayashi recovery rate were reported. Pre- and post-operative image were utilized for the assessment of post-operative effect. Peri-operative complications were recorded to assess the safety of the gantry crane technique. Results: The JOA score increased from 10.56 ± 3.76 preoperatively to 12.94 ± 3.33, 13.56 ± 3.48, 13.94 ± 3.32, 14.17 ± 3.70 and 14.06 ± 3.54 in 3 days, 3 months, 6 months, 12 months and 24 months after surgery, respectively. The post-operative JOA scores were improved with statistical significance at the level of P < 0.05. The recovery rate was (39.09 ± 33.85) %, (51.35 ± 42.60) %, (55.79 ± 36.10) %, (64.98 ± 29.24) % and (60.98 ± 35.96) % for 3 days, 3 months, 6 months, 12 months and 24 months after surgery, respectively. There were 2 cases of SSI (surgical site infection), 1 case of NI (neurovascular injury) and 1 case of cerebrospinal fluid (CSF) leakage. Conclusions: This study highlights a safe and effective technique, the gantry crane technique, for treating severe thoracic spinal stenosis and myelopathy caused by TOLF. [ABSTRACT FROM AUTHOR]

Gantry crane systems are often used in a variety of industrial applications to move and raise enormous weights. The process of transferring loads and weights in crane systems has always occupied the interest of researchers because of its importance in maintaining the safety of workers on the one hand and preserving the load itself from damage as a result of its swing and the possibility of it colliding with surrounding objects on the other hand. This paper's primary goal is to use a PID controller to regulate the position and swing of a GCS utilizing genetic algorithms (GA) and firefly algorithms (FA). Analytical techniques are used in the mathematical model, while Simulink in MATLAB is used in the PID model. This technique gave excellent results compared to either using the genetic algorithms (GA). [ABSTRACT FROM AUTHOR]