Unloading Process Research Articles

Implementation of Tuna Traceability in Ocean Fishing Port of Nizam Zachman Jakarta

Nizam Zachman Fishing Port (PPS Nizam Zachman) is one of fishing ports in Indonesia that implemented traceability and has export-destination to the United States and the European Union. However, previous study showed that documents recording and fish handling activities in the fishing port were poorly managed. Objectives of this study were to identify structure of supply chain, formulate obstacle factors of traceability, and recommend implementation actions of traceability. Data were collected through observation and interviews with longline tuna fishermen and tuna processing entrepreneurs. Subsequently, data were analyzed by applying descriptive and GAP analysis. The results showed that supply chain of tuna fisheries at PPS Nizam Zachman was started from fishermen, fish landing center, and ended at tuna processing industries. Regarding traceability implementation, 83% of activities at the Nizam Zachman fishing port met the standard. However, improvement was still required for documentation process at fishermen and processing phase, in addition to tuna handling procedures. Factors that impede traceability include e-logbooks filling, tuna handling at unloading process; 1) No regular checking on temperature at every 2 hours; 2) slow loading and unloading speed; 3) Fish are exposed to the floor during transportation process, no refrigerated vehicles were used during transportation process, and no electronics documentation. Some actions to overcome traceability implementation problems are: 1) evaluating and monitoring the fishermen activities; 2) doing periodic quality control in the field; 3) managing collaborations between the government and NGOs and tuna fisheries industry associations.Keywords: GAP analysis, supply chain, traceability, tuna export, tuna handling

Prinsip Tanggung Jawab Pengangkut Pada Pengangkutan Laut Di Indonesia

The carrier as the operator of transportation plays an important role in smoothing the flow of goods and people from one place to another. The safety of goods must be accounted for both to the delivery of the goods and to the parties concerned / interested. In the operation of transporting goods by sea, there is a possibility that losses will beincurred or it can also be called the risk that will always arise. Risks that arise can occur during the process of shipping, loading or unloading or storage. This study uses a normative juridical approach, which analyzes existing legal materials such as laws and regulations, regulations related to the transportation of goods in the field and international agreements. This research examines how the process of carrying out the transportation of shipping goods by sea and how the principle of the responsibility of the carrier in sea transportation according to Law No. 17 of 2008 on shipping. The results of this study consisted of various stages, namely the stages of preparation, loading, transportation, unloading, and completion. Article 57 point 28 of the Job Creation Law requires every ship to have a ship safety certificate. The responsibility ofthe carrier is regulated in Articles 40 and 41 of the Shipping Law and in Article 477 of the Indonesian Commercial Code.

Optimalisasi Proses Bongkar Muat Minyak Produk di Dermaga Curah Cair PT. Pelindo III (Persero) Cabang Tanjung Emas Semarang

PT. Pelabuhan Indonesia III (Persero) branch of Tanjung Emas Semarang is a BUMN provider of port services. One of the services provided is the operation of ships at the port, such as loading and unloading activities. One of the loading and unloading activities is loading and unloading product oil at the liquid bulk dock. During the loading and unloading process of product oil, several obstacles or disruptions may occur which cause delays during the loading and unloading process, thus reducing the performance of the Port Business Entity. This study aims to determine the inhibiting factors originating from labor and other factors and to determine the efforts to overcome these obstacles. The method of data collection was carried out by observation or direct observation at the location for 3 months, interviews, and literature study. The results showed that the inhibiting factor of labor resulted in less optimal loading space and tank washing. In addition, the inhibiting factor also comes from damage to loading and unloading supporting equipment and bad weather conditions. This study provides recommendations for each inhibiting factor to be handled properly according to the procedure so that it is expected to provide positive results, namely the smooth loading of product oil at the liquid bulk dock of PT. Pelabuhan Indonesia III (Persero) Semarang branch of Tanjung Emas.

Laser-driven flyer plate impact: Computational studies guided by experiments

We present a computational approach using a multimaterial, arbitrary Lagrangian–Eulerian code termed ALE3D to model the nanosecond/micrometer dynamics of the launch of 0.5–4.5 km/s laser-driven metal flyer plates and the impact with stationary targets of Pyrex and fused silica glasses, and Lexan and Plexiglas polymers, producing pressures in the target in the range of 5–20 GPa. The simulations are compared to experimental results where the flyer velocity profile and the velocity profile imparted to the target material were measured with high-speed velocimetry. The experimental flyer launch by a high-intensity pulsed laser is modeled by depositing heat into a thin vaporizable layer under the flyer plate. This model produces a flyer plate that has not been exposed to the laser pulse, allowing us to compare the properties of the real flyer to a simulated ideal flyer. The simulations of target impact are generally in good agreement with the experiment except at the highest impact velocities where the shock release process in the experiment is slower than that in the simulation. The cause of this disagreement is attributed to an inadequate description of the shock viscosity during the nanosecond unloading process.

Modelling of Springback in Tube Bending: A Generalized Analytical Approach

Bending is widely used for manufacturing of lightweight tubular parts and structures in many industrial clusters. In tube bending, springback is an important deformation behavior since it causes crucial problems related to the accuracy, quality, and properties of the bent tubular parts. This research presents a generalized analytical solution for springback in tube bending, enabling accurate and efficient analysis of springback for bending of general tubular materials, in particular, for the tubes with tension-compression asymmetry. Via comprehensively considering the critical parameters related to material, geometry, and process, the neutral layer shifting was analytically modeled for an accurate solution of stress/strain distributions in bending deformation. In tandem with this, by introducing the deformation history affected nonlinear degradation of elastic modulus and the dimensional change of tube section into the analysis of unloading process, an analytical springback model was established. By taking the rotary draw bending of high-strength titanium tubes as a case study, the developed analytical modelwas carefully evaluated, showing its good efficiency for springback prediction—particularly for the large-angle (≥ 90 deg.) forming cases with an average relative error below 5.79%. Based on the model, the effects of the critical parameters related to material, geometry, and process on neutral layer shifting, moment, and springback were thoroughly studied for a better understanding of the sensitivity of springback to these influential factors.

Analysis of dust dispersion in the loading of a bulk carrier ship using CFD and DEM

Dust generation and dispersion continue to be a major concern for many in the industries that rely on bulk materials handling, and the ability to predict dust generation and dispersion remains challenging. This study looks at the use of computational fluid dynamics (CFD) and discrete element method (DEM) as a means of predicting dust generation and dispersion. The paper outlines work completed on predicting dust dispersion during the loading process of a bulk carrier using the Rotabox™ system for a stevedoring company at a port in Australia. CFD simulations are conducted to analyze the induced air flow generated inside the cargo hold of a bulk carrier including typical cross-wind conditions. Coupled CFD-DEM simulations are conducted to analysis the air flow inside the cargo hold driven by the unloading of the bulk material. Dust particle free-settling time is used to assess the dust cloud formation and dispersion based on the flow conditions predicted by CFD-DEM simulations. The study finds that the unloading process is likely to disperse dust into the cargo hold at a level that without dust suppression would result in dust being dispersed into the broader environment by the typical cross-wind conditions at the port.

Experimental Study on Triaxial Unloading Failure of Deep Composite Coal-Rock

With the deep mining of coal, the phenomenon of high ground stress is more likely to cause dynamic disaster. In view of the above problems, this paper takes the unloading process of coal mining as the background to study the effects of mining rates under different conditions on the mechanical properties and triaxial failure criterion of composite coal-rock, so as to provide a theoretical basis for the prevention and control of dynamic disasters in coal mines. The composite coal-rock models with a composite ratio of 1 : 1 : 1 were tested under different unloading rates or confining pressures. The results show that the triaxial unloading process of coal-rock can be divided into five stages: compaction, single elasticity, elastic-plastic unloading, partial fracture, and complete fracture. In this paper, the failure criterion of composite coal-rock triaxial unloading is derived. The unloading rate has an exponential relationship with the triaxial compressive strength, and the relationship between initial confining pressure and compressive strength is linear. The triaxial compressive strength is determined by both. The peak strains ε of all samples under different unloading conditions were around 0.01. And initial confining pressure had an influence on the strain variation trend during the unloading of composite coal-rock. The higher the initial confining pressure, the greater the elastic modulus. In addition, an increase of initial confining pressure led to the increase of the total energy converted into dissipated part in the process of fracture and caused the obvious increase of the rebound characteristics of the curve. However, the unloading rate had no influence on the strain trend.

Difference Analysis on Sandstone Permeability After Treatment at Different Temperatures During the Failure Process: A Case Study of Sandstone in Chongqing, China

The channels of underground coal gasification (UCG) can be divided into three regions according to different temperatures. In order to explore the permeability characteristics of rocks in different temperature regions, permeability experiments were carried out under cyclic loading of rocks after heating at different temperatures, and the permeability of rock during the cyclic loading and unloading process after high-temperature treatment was obtained. The evolution characteristics of rock permeability in each cyclic loading and unloading process were analysed, and the permeability of different samples were compared. The results show that the initial permeability of rock treated at different temperatures clearly varies. The critical temperature of sandstone is 400 °C. After exceeding this temperature, the permeability of the rock samples generally decreases with the increase in the number of cycles but increases rapidly in the failure stage. The characteristic permeability values ( $${K}_{0}$$ , $${K}_{\mathrm{m}}$$ and $${K}_{u}$$ ) and permeability index ( $$\eta $$ ) of rock treated at different temperatures are dependent on temperature. Compared with 200 °C, the characteristic permeability value of the rock treated at 800 °C tends to gradually stabilize during the whole process of cyclic loading and unloading, and the permeability recovery of the rock is low. By comparing the increment coefficient ( $$\xi $$ ) of the permeability index of each cyclic loading and unloading process, it can be seen that the permeability characteristics of rocks undergoing the same stress path show a completely different change trend under the influence of different temperatures. These results are helpful for understanding the mechanics and permeability of rock under the influence of different temperatures, and provide a reference for site selection of UCG.

MECHANICAL PERFORMANCE OF TWO-WAY SIMPLY SUPPORTED STEEL-PLATE COMPOSITE SLABS UNDER CONCENTRATED LOAD

According to the test results of 5 groups of 33 simply supported steel-plate composite (SC) slabs, the deformation modes of the SC slabs are categorized into a flexural deformation mode and a punching shear deformation mode. Theoretical calculation formulas for the resistance and the stiffness are derived. The resistance function model of the SC slabs is proposed, considering the whole loading and unloading process. The accuracy of the model is verified through the existing test and numerical simulation results. Based on this model, the influence of the steel ratio, of material strength, and of connector layout on the deformation mode and on the energy dissipation capacity of the SC slabs are studied. The results show that the steel ratio and steel plate strength have great influence on the bearing capacity and on the energy dissipation capacity of the SC slab, while the influence of the concrete strength is not obvious. In order to make full use of the mechanical properties of the steel plates, the steel ratio and steel plate strength should be reasonably limited, or the arrangement of connectors should be strengthened to ensure the composite action. Since different design parameters may lead to different deformation modes and failure sequences, the design parameters should be optimized based on specific demands.

Modelling of a production process of irreversible strains in a material of a thick-walled cylindrical tube under the influence of inner pressure

This article considers the processes of the accumulation of irreversible strains in an elastoviscoplastic material of a thick-walled cylindrical tube in the framework of small strains. The material is deformed under the action of uniform inner pressure changing with time. Irreversible strains accumulate in the material by means of two different mechanisms, namely creep and plastic flow. Initially, whereas stresses increase in the deformed body due to mechanical influence, irreversible strains are produced as creep strains because of the viscous material properties. When the stress state reaches a loading surface, the production mechanism of irreversible strains becomes plastic. When unloading, this sequence in the production mechanisms is opposite, i.e. the fast plastic mechanism is replaced by the slow viscous one. The continuity in the growth of irreversible strains is provided by the corresponding setting of creep and plastic potentials. The possibility of the use of these potentials in the form of piecewise linear functions is investigated. It makes possible to use the developed mathematical formalism of the ideal plasticity theory. The creep and plastic flow processes under increasing and constant inner pressures are considered. The unloading process and repeated plastic flow under decreasing inner pressure, the stress relaxation after the full removal of a loading force are investigated. The reversible and irreversible strains, stresses and displacements in the medium are calculated. The laws of the motion of elastoplastic boundaries in the cylindrical layer are determined.

Experimental and Numerical Investigation of PA66 Fabrics Coated/Uncoated PVC by Biaxial Tensile Tests

Automobile airbags have become mandatory safety components in many countries. In this study, the PA66 (polyamide 66) airbag fabric was tested with and without a surface coating of PVC (polyvinyl chloride). Cyclic loading and unloading experimental conditions were defined according to the loading characteristics of the airbag deployment process. To determine mechanical properties such as elastic modulus and stress-strain curves for the two materials, biaxial loading/unloading cyclic tensile tests were carried out using a DIC (Digital Inspection Camera) to monitor the field strain process. Quadratic polynomial regression was used to fit material constitutive models of each loading and unloading process to the test data. The material subroutine VUMAT was encoded and applied to the simulation of the biaxial tensile testing of the fabrics. There was good agreement between the experimental and simulation results, which verifies that the quadratic polynomial constitutive material model is suitable for the study of coated and uncoated PA66 automobile airbag fabric. Hence, the material behaviour of automobile airbag fabrics can be modelled accurately.

Deformation and failure characteristics of sandstone subjected to true‐triaxial unloading: An experimental and numerical study

AbstractIn this research, we conducted both laboratory experiments and discrete element simulations to investigate the influence of maximum principal stress level on true‐triaxial unloading behaviors of sandstone samples. The results show that as the level of σ1 at the unloading point increases, the ultimate bearing capacity of sandstone sample is increasingly strengthened, while the sample collapses more easily during the unloading process, and the failure mode of sample changes from mixed tensile‐shear failure to shear failure. With the increase in the level of σ1, the accumulative micro‐cracks at the unloading point and micro‐crack generation rate during the unloading phase exhibit increasing trends, while the ratio between the number of tensile micro‐cracks and shear micro‐cracks generally shows a downward trend. The formation of macro fracture in sandstone sample is closely related to the material inhomogeneity and true‐triaxial stress state.

Mechanical Characteristics of Frozen Sandstone under Lateral Unloading: An Experimental Study

The lateral unloading strength and deformation of surrounding frozen rock are the key parameters for safety evaluation of frozen shaft construction. A low-temperature and high-pressure rock triaxial test system was used to simulate freezing construction, and a constant axial pressure unloading confining pressure test was carried out on frozen sandstone. The effects of freezing temperature, initial confining pressure, and unloading rate on the strength, deformation, and failure modes of frozen sandstone are studied. The main results of the study are as follows: (1) under the initial confining pressure of 20 MPa, the temperature of the sandstone decreases from 20°C to –5°C, and the peak stress and elastic modulus of triaxial compression increase by approximately 3 times. Under lateral unloading conditions, the peak stress of frozen sandstone is about 2∼3 times that of 20°C sandstone, and the peak strain of 20°C sandstone is smaller than that of frozen sandstone. The temperature of frozen sandstone decreases and the rate of increase in the peak stress of triaxial compression is slightly less than the rate of increase in the peak stress of lateral unloading. (2) The initial confining pressure of frozen sandstone increases, the growth rate of axial and radial strain increases, the radial strain dominates the failure process, and the lateral unloading strength decreases significantly. (3) The lateral unloading rate of frozen sandstone increases, the peak strength increases, and the axial and radial strain decrease. At a low unloading rate, partial creep deformation occurs. (4) The frozen rock sample undergoes tensile splitting failure under lateral unloading. According to the stress-strain curve of the frozen rock sample, the relationship between changes in the deformation modulus and changes in the confining pressure unloading amount during the unloading process of the rock sample is obtained.

Study on the Permeability Change Characteristic of Gas-Bearing Coal under Cyclic Loading and Unloading Path

Using the self-developed three-axis servo fluid-solid coupling system with gas-solid coupling of gas-bearing coal, the variation law of the permeability of gas coal under the stress cycle loading and unloading path was studied. The qualitative and quantitative relationships between permeability, axial force, and radial stress of gas-bearing coals were established, and the variation law of permeability of gas-bearing coals was discussed. The results show that (1) different cyclic loading and unloading stress paths correspond to the permeability characteristics of different gas-bearing coals. (2) Permeability of gas-bearing coal decreases with the increase of axial stress and radial stress, and it has a logarithmic function with axial stress and radial stress. This shows that axial stress and radial stress are important factors affecting the permeability characteristics of gas-bearing coal. (3) Under the same stress loading and unloading conditions, the axial stress is less than radial stress on the permeability of gas-bearing coal. In the cyclic loading and unloading axial stress process, the permeability of the gas-bearing coal varies by a smaller extent than the cyclically unloaded confining force. (4) The cumulative damage rate of gas-bearing coal under axial stress gradually increases with the increase of the number of cycles of loading and unloading, and the rate of the cumulative damage rate of permeability is less than the corresponding rate of radial stress.

APPLICATION OF JOB SAFETY ANALYSIS (JSA) METHOD IN IDENTIFYING THE RISK OF WORK ACCIDENTS IN CHARGED MANPOWER IN BUNGKUTOKO PORT, KENDARI CITY

Background: Data from the Ministry of Manpower of the Republic of Indonesia that the number of work accidents in Indonesia in 2016 was 101,368, in 2017 there were 123,041 cases, in 2018 there were 173,415 cases. At the end of September 2019 there were 130,923 cases and there were 6 people who died every day. On September 2019, the sectors that contributed to the relatively large number of work accidents were the processing industry with 50,358 (38.46%) cases, trade of 9,559 (7.30%) cases, transportation and warehousing 2,694 (2.06%) cases, and the rest 68,312 (52.18%) cases from other sectors. The same thing was reported by the Social Security Administration for Employment that there was an increase in work accidents by 40%, from 157,313 in 2018 to 173,105 cases in 2019. Methods: This research is quantitative research with a descriptive analytic research design and applied observational analytic approach. The population of all loading and unloading workers was 150 people divi ded into 3 teams, where each team consisted of 50 TKBM members of Bungkutoko Port, Kendari City. Result: This study found 3 work stages with the highest RPN value, namely, wrong in the lifting position in the stevedore of work process at the time workers lift goods and put them into the net, as well as in the cargodore of work process when workers stack goods on the truck with a value of 288, stumbling (cargo) which occurs in the stevedoring work process where The worker on the truck directs the crane and the net into the truck body with an RPN value of 192, and pinched by a lifting tool in the cargodore of work process when workers remove goods from the sling on the truck / remove the sling, with a value of RPN 144. Conclusion: There were 3 loading and unloading work processes, namely, stevedoring, cargodoring, and delivery with each work stage having potential hazards, the impact of hazards, and control efforts, and the person in charge of control efforts.

P-Wave Velocity and Energy Evolution Process of Concrete in Uniaxial Loading–Unloading Tests

P-wave velocity (Vp) is a significant parameter in characterizing the physical and mechanical properties of rock. The Vp of rock under different stress conditions will vary greatly. This study investigated the transformation of Vp under a single load and unload condition. Six concrete specimens were used. The unload level was 0 (uniaxial compression test), 0.1, 0.3, 0.5, 0.7, and 0.9 times the uniaxial compressive strength. Ultrasonic tests were carried out on the test processing. The loading and unloading process was analyzed as an integral part, and the process of secondary loading to destruction was divided into three sections—the compaction section, the elastic section, and the crack extension section—and the test results were analyzed using the least-squares regression method. Quadratic, linear, and logarithmic function relationships were found between axial stress and Vp at different sections throughout the test, and different polynomial relationships were found between the energy and Vp before and after the peak of Vp. A polynomial relation was found between the energy and Vp. In addition, the total input energy, elastic energy, and dissipated energy had a linear/quadratic function relationship.

Research and Optimization of the Three-Dimensional Printing Unloading Process for the Flexible Support Platform.

At present, a three-dimensional (3D) printing model is unloaded from the working platform manually, which hinders the automation of 3D printing. In this article, a new type of 3D printing auxiliary equipment called flexible support platform is designed to achieve automatic unloading. Unloading problems, especially its principle and influencing factors, are investigated in detail. We also study the build orientation optimization to find the optimum solution for unloading. The improved particle swarm optimization algorithm is applied to avoid falling into local optimum. Furthermore, we combine optimization for unloading with our previous work, which is in terms of support structure reduction. The unloading condition has been transformed into the calculation of added support structure owning to the process improvement, so that the optimized model with minimum support structure can be unloaded successfully. In a word, this article fulfills the need of 3D printing unloading research and achieves efficient automatic unloading.

A Robotic grinding station based on an industrial manipulator and vision system.

Due to ever increasing precision and automation demands in robotic grinding, the automatic and robust robotic grinding workstation has become a research hot-spot. This work proposes a grinding workstation constituting of machine vision and an industrial manipulator to solve the difficulty of positioning rough metal cast objects and automatic grinding. Faced with the complex characteristics of industrial environment, such as weak contrast, light nonuniformity and scarcity, a coarse-to-fine two-step localization strategy was used for obtaining the object position. The deep neural network and template matching method were employed for determining the object position precisely in the presence of ambient light. Subsequently, edge extraction and contour fitting techniques were used to measure the position of the contour of the object and to locate the main burr on its surface after eliminating the influence of burr. The grid method was employed for detecting the main burrs, and the offline grinding trajectory of the industrial manipulator was planned with the guidance of the coordinate transformation method. The system greatly improves the automaticity through the entire process of loading, grinding and unloading. It can determine the object position and target the robotic grinding trajectory by the shape of the burr on the surface of an object. The measurements indicate that this system can work stably and efficiently, and the experimental results demonstrate the high accuracy and high efficiency of the proposed method. Meanwhile, it could well overcome the influence of the materials of grinding work pieces, scratch and rust.

Suppression of sugar accumulation in coleoptile and mesocotyl cells by light irradiation to etiolated maize seedlings

Sugar accumulation in maize (Zea mays) coleoptile and mesocotyl cells was suppressed when etiolated seedlings were subjected to white light irradiation. Regulation mechanisms of sugar accumulation by light in cells of both organs were studied. Sucrose exudation from the endosperm was suppressed in light-treated seedlings. In addition, the activities and transcript levels of sucrose-phosphate synthase (SPS) in scutella were decreased following light irradiation. These results suggest that sucrose exudation from the endosperm is decreased by the suppression of SPS activities via downregulation of its gene expression. In coleoptiles and mesocotyls, light irradiation also decreased the activities and transcript levels of cell wall-bound invertase, suggesting that phloem unloading processes were suppressed. Thus, inhibition of both sucrose loading from the endosperm and sucrose unloading in coleoptiles and mesocotyls may be involved in the suppression of sugar accumulation in coleoptiles and mesocotyls irradiated with white light.

Cooling System with PCM Storage for an Office Building: Experimental Investigation Aided by a Model of the Office Thermal Dynamics.

The application of energy storage filled with phase-change material (PCM) is recently increasingly considered in active cooling systems. Such a design offers a higher density of thermal energy accumulation when compared with water storage. However, the optimum use of PCM storage is possible when its dynamic characteristics during the loading and unloading process are well recognized. Due to the complexity of the interaction between all elements of the heating/cooling system, a theoretical estimation of the profits is hard to perform in a reliable way. This is a significant problem at the design stage of the installation. In order to solve this problem, a laboratory experiment supported by a simulation was performed. The main aim of the experiment was to understand how the storage filled with the PCM in real-like conditions works. A test stand was made to investigate the effect of this solution on a reduced scale of 1:10. The PCM tested was RT15, a commercially available material that melts in the temperature range of 10–17 °C. The main parts of the stand are a chiller, an electric heater and thermal energy storage. The first two elements allowed a simulation of the thermal properties of the heat receiver, and their operation depended on the results from the numerical calculations. A lumped parameter model was used in mathematical description of the office building and its cooling system. The heat capacity of the system components as well as heat losses to the ambient environment were taken into account. The obtained results allowed the optimization of the control procedure and proved the validity of the applied investigation methods. This study confirmed the possibility of testing thermal energy storage with phase change material in real-like conditions.