Load Operation Research Articles

Human error identification and risk assessment in loading and unloading of petroleum products by road trucks using the SHERPA and fuzzy inference system method

Human error constitutes one of the primary causes of accidents, particularly in the context of loading and unloading operations involving road trucks, especially those carrying petroleum products. The process of identifying and evaluating human errors within these operations involves several key steps. Initially, all sub-tasks associated with loading and unloading are meticulously identified and analyzed utilizing Hierarchical Task Analysis (HTA), achieved through direct observation, document examination, and interviews. Subsequently, potential human error modes within each task are delineated using the Systematic Human Error Reduction and Prediction Approach (SHERPA). Finally, essential data for determining the criticality, probability, and severity of each error are gathered through expert elicitation and the application of Fuzzy Inference Systems (FIS).Through the analysis of SHERPA worksheets, a total of 37 errors during loading operations and 14 errors during unloading operations of petroleum products were identified. Among these errors, the predominant category during loading operations was action errors, comprising 31 instances, while communication errors were the least frequent, occurring only twice. Similarly, action errors were most prevalent during unloading operations, constituting 13 instances. These errors were further categorized and ranked based on their risk levels, resulting in 27 levels for loading operations and 12 levels for unloading operations.The consistent occurrence of action errors underscores the need for implementing control measures to mitigate their frequency and severity. Such strategies may include periodic training sessions to reinforce proper work procedures and the development of monitoring checklists, among other interventions.

Managing a Major Lube Oil Leak on a 150 MW Steam Turbine Power Plant

This paper focuses on the management of a major lube oil leak from bearing box No. 2 at the Sumsel-5 Power Plant. The steam turbine, a super high-pressure has been operational since April 2016. Overhauls in 2019 and 2023 addressed issues such as wear on oil deflectors, abnormal gland sealing clearances, and oil sealing wear. However, oil leakage persisted, necessitating further interventions. Rectification efforts included replacing oil deflectors, adjusting clearance, installing additional venting lines, the addition of a fiber gasket at bearing box No. 2 aimed to reduce and manage oil leakage. These measures resulted in a significant reduction in the oil leakage rate, from approximately 2826 ml/hr to 75 ml/hr during full load operation, representing a decrement of around 97.3%. Additionally, the frequency of lube oil top-ups decreased dramatically, leading to substantial cost savings for the plant. From a safety and environmental perspective, rectification measures mitigated fire hazards and reduced oil wastage, minimizing environmental impact. Regular monitoring of lubrication oil quality further ensures operational reliability. Although complete elimination of the oil leak was not achieved, the turbine continues to operate smoothly under manageable oil leakage conditions.

INVESTIGATION OF STRUCTURAL AND MECHANICAL PROPERTIES OF TUBING STEELS

The study of the structural and mechanical properties of tubing steels used in wells at oil and gas condensate fields is of particular interest due to the resource intensity of these systems and the high cost of their repair and restoration. Tubing is operated under conditions of increased loads under the influence of its own weight, internal pressure and constant contact with highly aggressive media. As a result of simultaneous exposure to corrosive media and operational loads, tubing is the most consumable downhole material. The destruction and, as a result, the breakage of the tubing suspension occurs as a result of mechanical abrasion and cracking of the pipe body, the development of fatigue cracks in the thread, etc. Contact with aggressive agents of the extracted fluid and reservoir waters leads to various types of corrosion damage: ulcerative, pitting, corrosion fatigue, corrosion cracking, meza corrosion, biocorrosion, etc. Corrosion foci are localized on the inner and outer surfaces of pipes. The problem is complicated by the increased content of carbon dioxide (CO2), hydrogen sulfide (H2S), as well as the presence of various bacteria in oil and gas fields.This article is devoted to the study of the mechanical characteristics and microstructure of tubing steels that were in operation under conditions of complicating factors and highly aggressive corrosive environment. Tubing pipes Ø73x5.5 of strength group E. were tested. The following research methods were carried out: visual inspection; determination of the chemical composition of steel; determination of hardness; uniaxial tensile test; optical microscopy.As a result of the tests, quantitative characteristics of the mechanical properties of the steels were obtained. A significant decrease in the hardness, tensile strength and yield strength of steel has been established under prolonged exposure to complicated operating conditions. Metallographic studies have established the contamination of steels with silicates of various shapes, amounting to 3 and 2 points according to GOST 1778. Microstructural studies have been carried out. The fine-grained ferrite-carbide structure of steels has been revealed. This structure corresponds to the heat treatment mode: quenching followed by tempering.

Inspection of wind turbine bolted connections using the ultrasonic phased array system

This study explores the inspection of bolted connections in wind turbines, specifically focusing on the application of Phased Array Ultrasonic Testing (PAUT). The research comprises four sections: Acoustoelastic Constant calibration, high tension investigation on bolts, blind tests on larger bolts, and Finite Element Analysis (FEA) verification. The methodology shows accurate results for stress while the bolt is under operative loads, and produces a clear indication of when it is above these loads and beginning to deform. PAUT emerges as a promising tool for bolt inspection, offering multiple imaging modes for simultaneous stress monitoring and defect detection. The study advocates for PAUT as a robust method to enhance wind turbine safety, longevity, and future in-situ testing.

Operational modal characterisation for long-term monitoring in offshore structures

In the effort to increase sustainability and help drive the energy sector to support oil and gas decarbonisation, the importance of identifying and characterising the current state of assets is becoming ever more crucial for operators, especially with regards to life extension and repurposing. Structural Health Monitoring (SHM) offers a promising and forward-thinking methodology for tracking asset integrity. In particular, Operational Modal Analysis (OMA) presents a proven, output only method for structure characterisation and modal tracking. However, Environmental and Operational Variations (EOV) can influence the modal properties of the structure making modal parameter estimation and tracking less reliable in the short- and long-term. This study employs an Automated Operational Modal Analysis (AOMA) methodology based on the combination of stochastic subspace identification and natural frequency histogram bin analysis for robust parameter extraction. The methodology is implemented in a complex of three bridge linked offshore platforms. Structural complexity, operational loading and significant modal couplings require sophisticated analysis. The preliminary results show discontinuity of the operational modes over a 6-month long monitoring period. The findings demonstrate the need of further analysis to understand the time-variant parameters which determine structural response across the asset lifetime.

A preliminary investigation of the inverse Finite Element Method applied to bridge structures

Deflection monitoring plays a key role in bridge Structural Health Monitoring, as deflection data may offer valuable insights into potential structural issues, such as cracks and corrosion. However, monitoring bridge deflections under operative loads presents challenges, particularly in scenarios where establishing a fixed reference point for displacement sensors is impractical, such as when a bridge spans a waterway or the sensors may be vulnerable to vandalism. In recent years, the inverse Finite Element Method (iFEM) has emerged as a possible solution. This method provides a load- and material-independent means of computing structural displacements from strain measurements, in real time at a minimal computational cost. Additionally, the iFEM can serve as a virtual sensing approach to monitor strains at locations lacking sensors, enabling the assessment of the fatigue life consumption at virtually any point in the structure. Despite its potential, applications of the iFEM in the civil engineering field are very limited, with no validation on full scale bridges has been performed to date. This study addresses this gap by investingating the application of the iFEM for bridge deflection monitoring through distributed strain measurements. The proposed approach is tested on experimental case studies, involving cross-validatiion of reference-free deflections inferred by the iFEM with those obtained from displacement sensors. This work contributes to the advancements of structural health monitoring methodologies in civil engineering, demonstrating the practicality and reliability of iFEM in bridge applications.

Performance of Smart Grid Based on Data Aggregation Using Wireless Communication Network Technology

With the advancements in technology, electrical energy has become a basic need to support every field of life including Electric Vehicles (EVs), Industry automation, security networks and communication systems. This, in turn, demands a high order of design, protection and measurement setup of power transmission from the energy source to the end users (load) with minimum loss of energy. All types of loads need a nominal supply voltage to operate, which necessary for its safe operation. Usually the nominal-rated voltage allows ±5% variation tolerance in the operation of loads, without affecting the equipment. The transmission lines that connect several smart grids are called as interconnection, by using it the stability and proficiency can be increased. It should provide reliable and secure communication, with a low-cost solution. Hence, in this research paper, an efficient communication system based on wireless sensor networks will be under consideration, to ensure good quality of service for smart grids. The initial two points that are required to be covered include 1) research on optimum network topology to connect several smart grids and 2) interference cancellation to avoid errors in transmission due to the induced field from the power lines. In addition, 3) the wireless sensor network will be used to support efficient data collection, self-organization of the network and data reduction by removing the redundancy. Finally, 4) development of data prediction algorithm to reduce the transmission rate and latency. Overall, these approaches will help in development of smart network to reduce the energy wastage, ensure nominal supply voltage, increased reliability and improved communication network as compared to existing solutions. The presented work includes the two sorts of wind and solar energy in ordinary working environments and illuminates the energy trade between buyers and power Production Company. The expense of power isn't thought about; however, the various buyers can pick the least expensive energy.

Identifying patterns in loading a gondola car body with reinforcing belts in the structure of side walls

The object of this study is the processes of occurrence, perception, and redistribution of loads in the body of a gondola car with reinforcing belts in the structure of side walls. In order to improve the strength of side walls of the gondola car body, it is proposed to strengthen them with additional belts. At the same time, it is reinforced with diagonal belts in three sections of the body on the side of the consoles, and in the middle section, 1/3 of the height from the lower strapping, with a horizontal belt. To determine the parameters for the execution of profiles in the reinforcing belts, the calculation of the gondola car body as a rod system was carried out. Based on the resulting values of bending moments, the moment of resistance of the cross-section of the profiles of the reinforcing belts was determined. The calculation of the strength of the body of the gondola car under the main modes of its loads in operation (I and III calculation modes) was carried out. It was found that the resulting stresses were 10.3 % lower than those occurring in a typical design of a gondola car body. The movement of the gondola car in the empty and loaded states was evaluated. A feature of the reported research results is that the improvement of the strength of the side walls of the gondola car body is achieved by increasing the rigidity of its frame. The field of practical use of the results is the engineering industry, in particular, railroad transport. The conditions for the practical application of results are the symmetrical distribution of reinforcing belts along the length of the gondola car body. This study results may contribute to improving the durability of gondola car bodies in operation, and accordingly to reducing costs for unscheduled repairs. Also, the findings could prove useful for designing modern structures of railroad cars

EXPERIMENTAL DETERMINATION OF FLOOR PANELS DEFORMABILITY OF A LARGE-PANEL SYSTEM BUILDING AFTER RENOVATION

This paper deals with a field tests of prefabricated reinforced concrete floor panels of a multistory building by the method of hydrostatic loading. Object of study is presented by 3 damaged floor slabs of a 9-storey residential building which was hit during the russian invasion. After renovation of panels using the constructive solution which consists of a reinforced build-up layer in the compressed zone (upper part) and additional external reinforcement in the stretched zone (lower part) connected to each other with the help of anchor connections, a series of tests with water loading were set. For creation of loading an inventory pool was used, which was gradually filled with water at a step of 1kN/m2. Maximum created loading level was 5kN/m2 which corresponds to the operational load. After reaching the maximum load, the panels were left under load for 15 hours and then fully unloaded in steps of 1kN/m2. For each panel two type of tests were established: first when panel had both upper and lower part of reinforcement, and second – when lower reinforcement within steel beams was removed. The idea of dismantling of steel beams connected with previously performed numerical analysis which gave to little difference in deflections of panels for these two cases. Deflection measurements at critical locations along with thorough visual inspection were conducted during the loading and unloading cycles. No damage was observed during the in-situ loading and unloading cycles. Maximum vertical deflection for panel before dismantling of beams lies in the diapason of 1.95-2.1mm and 2.31-2.4mm after they were removed. These results meet the requirements of regulatory restrictions on the maximum deflection equal to 20 mm for this structure. Difference in deflection for two cases doesn’t exceed 20% which allows to abandon the use of lower reinforcement in the form of steel beams in the future. As the size of the pool doesn’t cover the whole panel area, the equivalent uniformly distributed load was also calculated using Lira software. Keywords. Large panel system house, reinforcement, floor panel, method of hydrostatic loading, deflection.

Behavior of container berth structure under the influence of environmental and operational loads

Abstract Container docks, which are an essential component of the marine berth, are exposed to loads from various sources, such as self-weight, operation, and environment. In this study, four sets of combined loads to which the container berth is exposed were selected at the Um-Qaser Port in southern Iraq. The berth was constructed more than 40 years ago, which has to be verified according to latest specifications, and each set of combined loads was analyzed in three cases. In the first case, the piles were assumed to be fixed at the seabed, and in the second and third cases the piles were modeled as embedded in elastic and elasto-plastic sandy soil, respectively. The general-purpose finite-element software ABAQUS was used to model the various components to determine the maximum stresses, displacements, axial forces, shear forces, and bending moments due to dead, live, operate, berthing, mooring, waves, and seismic loads. It has been demonstrated that the impact loads of ships have a more significant impact on the structure compared to other loads. The calculated displacement when the piles are assumed to be fixed at the seabed level may be reduced by 50–94% of that calculated when the soil is modeled, meaning that assuming fixed piles yields inaccurate results, especially for deck displacements. However, this assumption was verified to yield reasonable results for shear forces at the pile head. It could also be noted that the elasto-plastic model of soil was more sensitive than the elastic model in displacement by 0.4–8% and bending moment by 0.3–34%, while it is less sensitive in axial force by 3–8%. The aim of this study is to obtain knowledge on the behavior and efficiency of container berth under the influence of different loads and the environmental conditions surrounding it.

Experimental study on peak shaving during preheating combustion for different coal ranks: Thermal modification and variable load operation

With the large-scale integration of renewable energy into the power grid, coal-fired power plants shoulder an enormous burden of peak shaving. In this study, the variable load characteristics of different coal ranks were extensively investigated on a 40 kWth down-fired test platform. Moreover, the preheating modification of fuel at ultra-low loads was investigated. A comprehensive evaluation coefficient (Eph) was established to characterize the reactivity of different coal ranks at wide loads. The determination criterion of combustion stability for variable load processes was modified. The results show that the preheating modification of different coal ranks was significant, especially for lower-activity coals such as anthracite and lean coals. The minimum loads after modification were 25 %, 25 %, 35 % and 40 % for ARG (lignite), SM (bituminous), RG (lean coal) and SH (anthracite), respectively. Furthermore, the preheating modification had a positive effect on increasing the variable load rate, which was positively correlated with Eph for different coal ranks. The maximum variable load rates after modification for ARG, SM, RG and SH were 2.78 %/min, 3.13 %/min, 1.79 %/min and 1.15 %/min, which corresponded to the optimum load steps of 25–30 %. The response rate of NO and N2O with time in the low-rank coal is faster than that in the high-rank coal during the variable load process, which is consistent with the trend of the variable load rate. In addition, the conversion of nitrogen oxides decreases and then increases with load, and the inflection points corresponding to AGB, SM, RG and SH are 40 %, 38 %, 70 % and 80 %, respectively. The NOx emissions were less than 335 mg/m3 (@6 % O2) for the different coal ranks during load changes.

Dual internal model control with improved load current feedback for enhanced dynamic performance in aircraft high‐voltage direct current brushless generator

AbstractIn order to enhance the dynamic performance of aircraft high‐voltage direct current wound rotor synchronous generator (WRSG) system under load variations, a dual internal model control (DIMC) method utilising improved load current feedback (ILCF) is proposed. It employs internal model controllers in both voltage and current loops, thereby significantly augmenting the system's disturbance rejection capabilities. Improved load current feedback is incorporated between the DC voltage loop and the field current loop. Additionally, a method for designing a feedback fitting function is established, enhancing the system's adaptability to changes in operational speed and load. The authors outline parameter design methods for voltage and current loops in DIMC, based on the internal model control principle. Adjustments to these parameters can further enhance the system's disturbance rejection capabilities. Finally, comparative experiments between the PI method with ILCF and the DIMC method with ILCF are conducted on a 15 kW WRSG experimental platform. These experiments demonstrate that the proposed DIMC method with ILCF optimises dynamic performance across the entire speed range, enhancing the competitiveness of WRSG systems in aircraft applications.

Experimental investigation for enhancing the performance of hydrogen direct injection compared to gasoline in spark ignition engine through valve timings and overlap optimization

Recent advances in hydrogen internal combustion technologies highlight its potential for high efficiency and zero carbon emissions, offering a promising alternative to fossil fuels. This paper investigates the effects of valve timings and overlaps on engine performance, combustion characteristics, and emissions in a boosted direct-injection single-cylinder spark ignition engine using both gasoline and hydrogen. Optimized direct hydrogen injection effectively eliminates backfires and hydrogen slip during positive cam overlaps, significantly reducing the pumping mean effective pressure. The study’s primary finding demonstrates the potential of hydrogen to operate as a direct substitute for a gasoline engine without necessitating changes to the cam profiles at the high load operation. Furthermore, the study demonstrates that hydrogen leads to much higher thermal efficiencies across a wider range of engine loads when operated at a lean, air-to-fuel ratio of 2.75. The engine operating with such a lean-burn hydrogen mixture keeps the engine-out NOx emission at ultra-low levels. Compared to gasoline, hydrogen exhibits greater stability and a reduced reliance on camshaft timing during engine operation.

Fatigue life prediction of metal materials under random loads based on load spectrum extrapolation

The impact of random loading on the fatigue life of mechanical components contains numerous uncertainties. This study aims to enhance the precision of life prediction by developing mean and amplitude distribution models based on the road load spectrum and extrapolating the operational load beyond the threshold value in the time domain. Additionally, it considers the influence of high cycle fatigue (HCF) and low cycle fatigue (LCF) loads on the initiation life of metal cracks. To address this, a load correction factor is introduced, and critical stresses for high and low cycle loads are proposed. Furthermore, a two-dimensional programmed load spectrum is prepared, taking into account the mean and amplitude. The accuracy and rationality of the fatigue life model are validated through examples using 45# steel and 316L, while experiments on engine support are conducted to confirm the effectiveness and accuracy of the over-threshold extrapolation life prediction method under random loading.

Optimizing Li Plating Behavior via Controlling Areal Capacity of a Cathode for Cycling Stability on 600 W h kg-1 Lithium-Metal Batteries.

To meet the requirements of long-range electric vehicles and aviation, the high-mass-loading electrode with high areal capacity is a promising solution to realize ultrahigh-energy lithium-metal batteries (LMBs). However, enabling the operation of high mass loading with a long cycling life is still a challenge without in-depth investigation. Herein, we figured out that the polarization appearing in the cycled lithium-metal anodes (LMAs) is responsible for the poor cycling of LMBs with high mass loading. Moreover, the origin of fast degradation of LMAs is affected by mass loading through the Li plating process, which is decided by the Li plating morphology. Hence, manipulating the mass loading can directly promote lithium reversibility and further mitigate cell polarization in LMBs, endowing high-mass-loading LMBs with excellent cycling stability. Consequently, we achieved an ultrahigh energy density (605 W h kg-1) of a 10.1 A h pouch cell with an excellent retention of 91.7% capacity and 86% energy after 50 cycles. The feasible strategy points out a promising approach for designing high-energy-density LMBs in the future.

Heat transport and load response characteristics of a molten salt solar tower power station engaged in peak regulation

Power system flexibility can be improved effectively, if the advantages of the peak shaving ability of molten salt solar tower power (STP) plant can be developed and utilized. In this paper, the heat transport and load response characteristics of the molten salt STP plant in the regulation process are studied, aiming at serving the development of the regulation method in the rapid peak regulation process. The steam generation system and turbine system models of a 50 MW STP station are established. Two load regulation methods and operation modes are used to investigate the inertia and delay effects of heat transfer and evaporation, as well as load response characteristics during the actual regulation operation, including steam generation system following (SF), turbine following (TF), constant pressure operation (CP), and sliding pressure operation (SP). The results show that when the plant load is reduced by 10% Pe at the rate of 3% Pe/min, the heat transfer of salt/water and the evaporation process of water in the whole regulation process have a 250 s delay compared with the load. The larger heat storage characteristics of the plant help to improve the load response speed. The load response speed of the plant is faster in SF mode. TF mode is beneficial to the safe operation of the plant. Considering the operational safety of thick-wall component, the recommended running mode is the collocation of SF and SP mode, TF and CP mode. The results show that the load change rate of 10% Pe/min is permittable under TF and CP modes. The conclusion of this paper lays a foundation for the formulation of a peak regulation strategy for molten salt STPs.

A novel strategy to enhance power management in AC/DC hybrid microgrid using virtual synchronous generator based interlinking converters integrated with energy storage system

Hybrid microgrids (HMGs) have a flexible structure, higher reliability, and both AC and DC MG merits. However, in this type of MGs, there are challenges such as accurate power sharing, the voltage control of the DC link, the AC side voltage and frequency stability, the negative impact of telecommunication delay, and so on. Therefore, a power management scheme is presented here that can perform proper and precise power sharing in a hybrid AC/DC MG. This HMG consists of one energy storage system (ESS) along with two interlinking converters (ILC) based on a virtual synchronous generator (VSG). Besides, the physical inertia of a MG is less than that of a power grid, hence, changing the output power of wind turbines and photovoltaic (PV) arrays might make system unstable. To overcome this challenge, virtual inertia is used. As the virtual inertia can be embedded with the VSG method, in this scheme, the VSG strategy is implemented to enhance the system dynamic behavior by imitating the synchronous generator kinetic inertia. The VSG-based ILC1 converter is used to establish interlinking and energy exchange between AC and DC sub-grids and share power. Also, other interlink devices including a bidirectional half-wave DC/DC converter integrated with the ILC2 are considered, which aim to control the voltage of the DC link and exchange part of the power between the AC and DC sub-grids. An ESS is placed between the bidirectional DC/DC converters and the DC link of the ILC2. Such a structure is referred to as a two stage interlinking converter with an ESS (TSILC-ESS). The power management system employed in AC/DC HMG according to the ILC controller is utilized to form the DCMG along with controlling the TSILC-ESS, providing additional and auxiliary services to the power grid. To assess the introduced scheme of both AC and DCMG to investigate VSG-based ILC1 and ILC2 in grid-connected and islanded operational mods, various resource and load profiles are assumed. The simulation study is performed in MATLAB/ Simulink environment to confirm the proposed method.

Data analysis and estimation of the conversion efficiency of bidirectional EV chargers using home energy management systems data

This study elucidates the authentic utilization of Vehicle-to-Home (V2H) system, a bi-directional DC charger for residential use and appraises power conversion losses incurred during V2H charging and discharging, utilizing data from commercial Home Energy Management Systems (HEMS). This approach offers the advantage of ascertaining operational efficiency within practical scenarios at a reduced cost relative to empirical data acquisition.The empirical examination of results revealed that V2H households exhibited more frequent connections to the charger and engaged in more substantial charging activities compared to Charging-only households.When estimating the power conversion efficiency in the context of V2H charging and discharging, a partial load efficiency curve was constructed for the input power of the V2H charger, thereby confirming that the peak efficiency closely approximated the nominal rated efficiency. These identified characteristics hold value for V2H system simulations. Furthermore, it was confirmed that a substantial standby power, ranging from 92 to 142 kWh per year, was generated when the V2H charger remained inactive in the sampled households. Additionally, the lack of reverse power flow to the external grid from the V2H system led to an observed increase in V2H partial load operation, resulting in a situation characterized by diminished conversion efficiency.

Interaction of ultrasonic guided waves with interfacial debonding in a stiffened composite plate under variable temperature and operational conditions

Stiffeners play a vital role in strengthening thin panels in a wide range of engineering constructions by reducing additional structural weight. However, these structures are vulnerable to issues such as interlayer delamination or skin-stiffener interfacial debonding due to high stress levels developed from external environmental conditions and operational loadings. In contrast, ultrasonic-guided wave (UGW) techniques exhibit an efficient and precise approach for monitoring discontinuities or damages in composite structures. There is a lack of research on understanding the characteristics of the interaction between UGW and interfacial debonding when in-plane edge loading and environmental factors are simultaneously taken into account. Therefore, this study is motivated by the need to develop a multiphysics numerical model which employs a commercially available finite element software, COMSOL Multiphysics®, to simulate UGW propagation in a stiffened composite plate with debonding at the plate-stiffener interface through a piezoelectric transducer under the combined influence of in-plane edge load and hygrothermal environment. The stiffened plate and piezoelectric patches are modelled with the tetrahedral element, and the bottom surface of the attached stiffener has a through-width 0.1 mm deep groove simulated for debonding. The developed FE model is validated against the results of the conducted experiments and those found in the available literature through the correlation coefficient. Further, the study conducts a comprehensive parametric investigation on stiffened cross-ply (0/90/0) laminated plates, considering variations in debonding size, in-plane load, and hygrothermal load intensity through the excitation of A0 mode. The acquired response is processed to compare the peak amplitude of various modes and energy of the waveform. Additionally, statistical indices such as normalised correlation moment (NCM) and variance of the continuous wavelet transform (CWT) peak are estimated to understand the impact of various parameters on waveform. The results show that the presence of a 90° lamina in the cross-ply laminate generates a low amplitude S0 mode in the scattered response. Moreover, a mode conversion from A0 to S0 mode is observed due to perfect bonding between the plate and the stiffener, providing insights into the bonding state in the panel. Furthermore, it is found that the magnitude of the in-plane loading marginally affects the peak amplitude of various modes in the scattered response. Additionally, when temperature intensity rises, the energy and amplitude of the UGW signals acquired through piezoelectric patches positioned in a direct line with the actuator gradually increase. The NCM value enhances with debonding regardless of exposed hygrothermal condition and reduces with increasing temperature intensity. In addition, the variance of the CWT peak reduces with debonding. The findings of this research are expected to be helpful for the development of efficient algorithms for detecting damages for structural health monitoring of stiffened composite panels.

THE INFLUENCE OF STACKING YARD UTILIZATION AND OPERATIONAL PERFORMANCE ON LOADING AND UNLOADING PRODUCTIVITY AT THE KOJA CONTAINER TERMINAL JOINT OPERATION

Indonesia is the largest archipelagic country in the world. Indonesia has extraordinary natural resources and human resources because of its strategic location between the continents of Asia and Australia and between the Indian and Pacific Oceans. Ports as trade gateways and providers of public services play a very important role in economic movements, and the economy plays an important role. very important in the economy. In the accumulation field utilization variable (X1) there are 13 indicators which are statements to be answered based on the suitability felt by the respondent. The questionnaire was created using a Likert scale which has answer options ranging from Strongly, no, disagree, disagree, not sure. , Agree and completely agree "Maximum loading and unloading productivity quality and in accordance with the set targets"; "The level of use of stacking yards for export activities is quite high" with an average of 4.5455, which means that respondents strongly agree. On the other hand, the lowest average is Information regarding the relationship between operational performance and loading and unloading productivity can be used to direct policy and strategic decisions.