Load Position Research Articles

Study the muti-bolt fastening under different load positions in gear rack drilling rig.

During the operation of drilling rigs, bolts are subjected to significant loads, rendering bolt groups vulnerable to failure due to uneven load distribution. This study investigates the multi-bolt load distribution characteristics of eight-gear and four-gear symmetric transmission mechanisms in drilling rigs. The spring stiffness method is utilized to analyze multi-bolt load distribution. A finite element model of the bolted connection is developed by integrating the structural shape and transmission mechanism. The model's accuracy is validated through a rack strain test under various loads. Based on the finite element analysis results, this study proposes an evaluation method for bolted connections using relative deformation difference. The impacts of bolt pitch, end distance, preload, and thickness of the derrick connection plate under different load positions on the connection are examined. This paper presents a methodology and conclusions that can inform the design of bolted connections for heavy-duty drive systems.

Mechanical behavior of round bamboo under transverse local compression

Bamboo is a material with low transverse mechanical properties. To study the mechanical behavior of round bamboo under transverse local compression, 60 round bamboo culms were subjected to three-point bending tests. The effects of different parameters on the transverse local compressive behavior were investigated experimentally. Finally, the transverse local compressive ultimate bearing capacity of round bamboo was estimated using prediction equations. The results indicated that under three load boundary conditions, axial cracks appeared on both sides of the specimens in the midspan region, dents of different sizes appeared at the loading points, and additional fractures occurred in the inner diaphragms of the specimens with the loading point at the node. The specimens subjected to point and line loads underwent brittle failure. Under the space-curve load, the specimens with a loading point at the internode exhibited ductile failure, whereas the specimens with a loading point at the node exhibited brittle failure. To obtain a favorable transverse local compressive ultimate bearing capacity, it was optimal to consider the space-curve load as the load boundary condition and position the transverse local compression at the bamboo node. The results of the prediction equations agreed well with the test results.

Launch Dynamic Simulation of a Compressed-Air Launcher for Fire Suppression

This paper focuses on improving fire suppression performance through the use of compressed-air launching technology. A launch dynamics calculation model of a compressed-air launcher is presented, developed using VC++ programming, to simulate the acceleration process of a fire-extinguishing bomb in a barrel. By analyzing the influences of various structural and initial parameters on interior ballistics variations, the effectiveness of the calculation model and program in accurately simulating the launching process is demonstrated. The calculation results indicate that the bore pressure follows a similar trend to that of traditional gunpowder launching. Additionally, it is found that specific structural parameters, such as nozzle diameter and gas cylinder volume, have a direct impact on interior ballistics variations. Notably, the nozzle diameter positively affects the peak pressure, muzzle velocity, gas transfer efficiency, and launch efficiency. To ensure an optimal launch effect and efficiency, the nozzle diameter should be selected to be more than half of the launcher caliber. Similarly, the gas cylinder volume positively influences the peak pressure and muzzle velocity while negatively affecting the gas transfer efficiency and launch efficiency. Furthermore, the initial pressure in the gas cylinder exhibits a positive linear relationship with both the peak pressure and muzzle velocity but a negative linear relationship with the gas transfer efficiency and launch efficiency. The loading position minimally impacts the peak pressure and muzzle velocity but slightly enhances the gas transfer efficiency and launch efficiency. Finally, it is observed that launch angles do not affect the interior ballistic process. The research findings provide valuable theoretical guidance for determining the working parameters of compressed-air accelerated fire-extinguishing bombs.

Flexible wood-based pH-responsive hydrogel excipient for rapid recovery of infected wounds

Infected wounds heal slowly and may become pus-filled, bloated, and feverish if left untreated. Wood is an ideal substrate for improving the mechanical properties of composites and increasing the number of loading positions because of the unique structure and excellent properties. In this work, after chemically eliminating some of the lingin and hemicellulose from wood, a flexible wood was obtained. The freeze-thaw approach was used to create a pH-responsive flexible wood-based hydrogel (FTS-G@PC) comprising polyvinyl alcohol (PVA) and chitosan (CS) crosslinked wrapped gentamicin (GS). It is particularly biocompatible because to the natural wood employed and the physically cross-linked hydrogel generated by cyclic freezing, and the pH responsiveness is more relevant for septic wounds. Results demonstrated that the surface stiffness of the modified wood was significantly decreased closer to the skin and that the flexibility and increased adhesion permitted excellent skin adaptation. In vitro experiments had revealed that FTS-G@PC had high cytocompatibility, pH-responsiveness, and a strong antibacterial. The dressing promoted wound recovery faster in a mouse model of infected wounds. Therefore, FTS-G@PC is one of the promising and excellent renewable dressings.

On analytical study of Griffith crack propagation in a transversely isotropic dry sandy punch pressured strip

Abstract The present study focuses on the propagation of a Griffith crack in an infinitely extending finitely thick transversely isotropic dry sandy strip with moving parallel punch pressure acting at the bounding surface of the layer because of the propagation of plane waves under mechanical point loading. Furthermore, the present model is developed using coupled singular integral equations, Dirac delta function & Cauchy-type singularities; it is applied to investigate the point load at the moving crack edge, and Hilbert transformation properties are also used to derive the stress intensity factor (SIF) with constant point loading in closed form. Numerical computation & graphical demonstrations have been provided to examine the influence of the prevailing parameters, viz. length & speed of the crack, pressure of the punch, sandiness parameter and different positions of point load, on the SIF for transversely isotropic dry sandy and also for isotropic material strips. A comparative study of the SIF at the tip of moving crack has been carried out for the transversely isotropic dry sandy strip and isotropic materials strip with and without punch pressure and sandiness to highlight some of the important peculiarities of the problem.

Parametric Instability of Stiffened Plates with Cutouts

The dynamic instability behaviour of stffined plates with cutout is of great technical importance for understanding the behaviour of the system. In the present study, dynamic instability behaviour of stffined plates with cutouts are investigated by using theJinite element method. The method of Hill's infinite determinants is applied to analyze the dymmic instability regions. Rectangular stilfened plates with cutouts possessing diferent boundary conditions, aspect ralios, varying mass and stffiess properties and varying number of stiffeners have been analyzed for dynamic instability. The influence of various parameters like effects of size of cutout, load position, aspect ratios, and boundary condition, other paramelers of stffined plates have been studied. The method highlights interesting effects when stffined plate with cutout is subjected to uniftrm in-plane edge load. In the structural modelling, the plate and the stffiner are treated as separate elements where the compatibility between these two types of elements are maintained. The present approach is moreflexible than any otherJinite element modelling in that the mesh division is independent of the location of the stiffeners.

Multiple equilibrium states of a curved-sided hexagram: Part II—Transitions between states

Curved-sided hexagrams with multiple equilibrium states have great potential in engineering applications such as foldable architectures, deployable aerospace structures, and shape-morphing soft robots. In Part I, the classical stability criterion based on energy variation was used to study the elastic stability of the curved-sided hexagram and identify the natural curvature range for the stability of each state with circular and rectangular rod cross-sections. Here, we combine a multi-segment Kirchhoff rod model, finite element simulations, and experiments to investigate the transitions between four basic equilibrium states of the curved-sided hexagram. The four equilibrium states, namely the star hexagram, the daisy hexagram, the 3-loop line, and the 3-loop "8", carry uniform bending moments in their initial states, and the magnitudes of these moments depend on the natural curvatures and their initial curvatures. Transitions between these equilibrium states are triggered by applying bending loads at their corners or edges. It is found that transitions between the stable equilibrium states of the curved-sided hexagram are influenced by both the natural curvature and the loading position. Within a specific natural curvature range, the star hexagram, the daisy hexagram, and the 3-loop "8" can transform among one another by bending at different positions. Based on these findings, we identify the natural curvature range and loading conditions to achieve transition among these three equilibrium states plus a folded 3-loop line state for one specific ring having a rectangular cross-section with a height to thickness ratio of 4. The results obtained in this part also validate the elastic stability range of the four equilibrium states of the curved-sided hexagram in Part I. We envision that the present work could provide a new perspective for the design of multi-functional deployable and foldable structures.

INTERFERENCE AND KEEL DESIGN SIGNIFICANTLY INFLUENCE SAGITTAL MICROMOTION IN CEMENTLESS UNICOMPARTMENTAL KNEE ARTHROPLASTY

AbstractIntroductionIn cementless UKR, early post-operative tibial fractures are 7x more common in very small tibias. A smaller keel has been shown to reduce this fracture risk, but its effect on fixation is unassessed. This mechanical study assesses the effect of keel interference and size on sagittal micromotion of the tibial component in physiological loading positions.MethodA high-resolution Digital Image Correlation setup was developed and validated to an accuracy of 50 micrometres. Variants of tibial components were 3D-printed: standard, no-interference, no-keel, and a new small keel. Components were implanted into bone-analogue foam which was machined to a CT-reconstructed small tibia, using surgical technique. Tibias were loaded to 200N in physiological loading positions: 8mm (step-up) and 15mm (lunge) posterior to midpoint, and micromotion was assessed.ResultsIn all tests, anterior lift-off was the largest micromotion observed. In ‘step-up’, a standard keel moved more than the no-interference and no-keel variants (340μm-vs-63μm-vs-30μm, p=0.002). In ‘lunge’ loading, the no-interference and no-keel variants moved more than the standard (826μm-vs-1003μm-vs-521μm, p=0.039).The small keel experienced less micromotion in ‘step-up’ (245μm-vs-340μm p=0.233, overall p=0.009) and ‘lunge’ (378μm-vs-521μm p=0.265, overall p=0.006) than the standard keel.ConclusionThe keel protects against large tibial micromotion during lunge movement. Counterintuitively, interference increases micromotion during step-up movement, likely due to implant pivoting around the bone-keel interface. Results suggest patients should be advised against lunge movements early post-operatively. The new smaller keel fixes similarly or better than the standard keel, making it viable for replacing the standard keel to potentially reduce fracture risk.

Neuro-fuzzy-based anti-swing control of automatic tower crane

Controlling the position of the final load and the anti-swing control of the loads during the operation of the tower crane are challenging tasks. These are the most important control issues for safe operation, which are difficult to achieve easily with conventional control systems. Hence, the need to integrate the concepts of soft-computing into the tower crane control system. The aim of this research work is to design an adaptive-network-based fuzzy inference system (ANFIS) controller to move the payload to the final position with the lowest possible swing angle. To evaluate the ability of the proposed controller to meet the control requirements, its performance was compared to three other controllers: a conventional proportional derivative (PD) controller, a fuzzy-tuned PD controller and a fuzzy controller. MATLAB-based computer simulations of the crane and controllers were carried out to verify and compare the performance of the proposed controllers. The obtained results show the effectiveness of the ANFIS-based controller in adjusting the load position while keeping the load fluctuations small at the final position. The load oscillation angle is about ±2.28° with the ANFIS controller while it is about ±10° when using the PD controller. In addition, only one ANFIS controller is used for both load position and swing angle control.

Study on position tracking algorithm of large-inertia artillery with terminal sliding mode control

The large-inertia artillery has complex structure and high coupling between components. Due to the processing technology, the error between motor shaft position and the actual load position is inevitable and hardly to be compensated. The situation get worse when the system running in high speed, where the error changes more violently and so-called "vibration" phenomenon shows up. The study establishes a detailed mode of servo system including double-motor control, position-loop control, moment model of gears, and feedback of position sensors. Then a position tracking algorithm with terminal sliding mode control is proposed and verified in artillery system. The experiment shows that this algorithm effectively eliminates the "vibration" phenomenon, enables the servo computer to directly use the load position of the artillery as the control variable, and improves the position tracking accuracy and operational stability of artillery system.

Progressive Collapse Analysis of Intermediate Moment-Resisting Steel Frame under Fire-Induced Column Failure

This paper evaluated the progressive collapse robustness of steel intermediate moment-resisting frames (MRFs) under different fire-induced column failure scenarios. For this purpose, 3-, 7-, and 12-story intermediate MRFs were modeled numerically and analyzed under different gravity and fire loads. The effects of the seismic design requirements, number of stories, gravity load ratio (utilization ratio), and redundancy and position of the heated column were discussed. Because the investigations included models with different number of stories and different seismic to gravity load ratios, the results can be applied for a wide range of IMFs. The results show that none of the studied frames in the high seismic zone with a low gravity loads ratio experienced progressive collapse under any of the considered fire scenarios. However, by increasing the ratio of gravity loads in frames, the vulnerability to progressive collapse was increased. This suggests that in areas with a lower risk of environmental lateral loads, where MRFs generally are designed for gravity loads and smaller lateral forces, the progressive collapse robustness of MRFs under fire-induced column failure should be given serious consideration. In addition, the results show that the possibility of progressive collapse under the fire-induced column failure scenarios in the first story of low-rise frames is more than that in the first story of high-rise frames, and generally low-rise frames are more vulnerable to progressive collapse than high-rise frames. Furthermore, the possibility of progressive collapse under fire scenarios in the upper stories is more than that in the lower stories, especially for the top story. In this study, a new combined failure mechanism for global collapse of MRFs was identified.

Handling System Complexity in Zonal E/E Architectures

As conventional electric/electronic (E/E) architectures reach their limits, new architecture concepts are being researched to make the complexity of the vehicle and its components manageable. Zonal architectures are a promising option, but there is a lack of methodology for developing them. This paper shows a method to design zonal E/E architectures, in particular their power supply. At first, the zonal vehicle power supply system (PSS) of the UNICARagil vehicle platform is presented. The UNICARagil project is a collaboration of 15 German research institutes and companies with the goal to develop disruptive modular architectures for agile automated vehicle concepts. To design a zonal, in regards of the vehicle functional architecture optimized PSS, it is necessary to cover the crucial aspects of both, the vehicle and the PSS, as well as their interfaces. A method is presented that optimizes the design of the PSS in zonal E/E architectures. The optimization is achieved by clustering the electric load positions to identify suitable positions for the zone control units (ZCU), wire harness routing by Dijkstra algorithm and integration of the entire PSS in vehicle packaging concepts. The aim is to reduce component cost, packaging restrictions and system complexity, which will result in a cut of development effort and a gain in user experience. The system complexity is therefor evaluated by metrics as well as in combination with other criteria by a simulation study.

An analytical approximate solution for stress and displacement around a shallow circular tunnel excavated under concave slope topography

For shallow buried tunnels under slope, overloading on the ground surface and unloading of excavation both significantly influence the stability of the tunnel surrounding rock and slope. This study proposes an analytical approximate solution for the stress and displacement around shallow buried circular tunnel under slope boundary. In derivation process, the original problem is divided into two models: Model A is a slope plane without any holes subjected to gravity and surcharge load along the ground surface, and Model B is a tunnel contained in a slope plane loaded by released stresses along the tunnel boundary. Furthermore, Model B is decomposed into another two models: Model B1 represents a slope without holes subjected to virtual surface force along the ground surface, and Model B2 is an infinite domain containing a tunnel loaded by another virtual surface force along its boundary. Two sets of virtual surface forces are then achieved by an iterative calculation. The solution, which strictly meets all stress boundary and compatibility conditions of the original problem, are ultimately solved by superposing the solution of Models A, B1 and B2, respectively obtained by the method proposed by the authors (Models A, B1) and complex variable theory (Model B2). The convergence of iteration process and good agreement between the derived and numerical results under the same assumptions verify the correctness of the proposed solution. Furthermore, a parametric investigation is performed to investigate the influence of surcharge load position, slope topography and tunnel position on the stress and displacement around the tunnel and near the ground. The proposed solution is of great value for the conceptual understanding of mechanical behavior of shallow tunneling in slope terrain and for verifying the numerical models. Moreover, the solution is useful for the preliminary design of tunnels at shallow depth under slope topography.

Study on Fatigue Cracking of Diaphragm's Arc Opening of OSD in Steel Bridges by Using Biaxial Stress Method.

Changes in loading position have a significant impact on the stress field of each vulnerable area of an orthotropic steel deck (OSD). The arc opening area of the diaphragm and the connecting area between the U-rib and the diaphragm under the moving load are prone to fatigue cracking. By comparing the stress responses under different methods, the hot spot stress (HSS) method is used as the main stress extraction method in fatigue performance evaluation. The control stress of fatigue cracking was analyzed by comparing the direction of the principal stress field with the crack direction in this experiment. According to the stress amplitude deviation under the biaxial stress state, a set of methods for evaluating the effects of in-plane biaxial fatigue was developed. An improved luffing fatigue assessment S-N curve was applied to analyze the fatigue life of the diaphragm's arc opening area. The results show that when the moving load is exactly above the connection of the deck and the web of the U-rib on one side, it is in the most unfavorable position in the transverse direction, and the diaphragm is mainly under the in-plane stress state. The longitudinal range of the stress influence line of the arc opening is approximately twice the diaphragm spacing. Two to three stress cycles are caused by one fatigue load. Fatigue crack control stress is the principal stress tangential to the arc opening's edge in this area. The normal direction of the principal stress in the model test is roughly consistent with the crack initiation direction. The variation in the stress amplitude deviation in this area is caused by changes in the action position of the moving load. When the moving load is at a certain distance from the involved diaphragm, it is reduced to zero, implying that the in-plane fatigue effect is the greatest in this area.

Acoustic Emission Characterization and Cracking Characteristics of Reinforced Concrete Pipe

Acoustic emission (AE) and digital image correlation (DIC) technology were used in this study to monitor the behavior of reinforced concrete pipe (RCP) in the optimized three-edge bearing test (TEBT). At the same time, the AE source location of different pipe sections was simulated. The results show that the whole compressive loading process for RCP could be divided into 3 to 4 stages. Both the AE counts and AE energy could well characterize the cracking of concrete, and AE energy was more sensitive to the breaking of steel bar. The amplitude and duration of AE signal produced by the breaking of steel bar were larger than those produced by the cracking of concrete. The AE frequency for concrete cracking was relatively scattered. The AE frequency for steel bar breaking was small and concentrated, and this frequency distribution showed an exponential decreasing trend. The results of optimized AE source location showed that the generation and development of cracks occur in the initial loading stage. The results of multi-index analysis showed that the cracks in the top (loading position) and the bottom (bearing position) of the RCP show that the cracks extend from the inner wall to the outer wall, while the cracks on the left and right sides perpendicular to the loading direction show that the cracks extend from the outer wall to the inner wall.

A new experimental method to measure and calculate the tensile strength of concrete

Introduction: A new method is introduced to test the tensile strength of concrete: the cylinder transverse splitting test. Compared with the cylinder splitting (or Brazilian) test, the cylinder transverse splitting test involves different load positions and offers the advantages of doubling the data volume with the same number of specimens and improving the detection accuracy.Methods: Finite element analysis software was used to simulate the concrete cylinder transverse splitting test and the stress distribution on the failure surface was determined.Results and Discussion: The results show that the fracture of a cylinder is mainly determined by tensile stress. The splitting strength of normal concrete and crumb rubber concrete, a new environmentally friendly concrete material that has gathered considerable attention in recent years, was obtained by cylinder transverse and cube splitting tests. The cylinder transverse splitting test data show a stable correlation with the cube splitting test data and well characterize the concrete strength. The relationship between the cylinder nominal transverse splitting strength (f2) and cube splitting strength (f1) was established on the basis of linear analysis of the test data: f1 = 0.51f2. The calculated cube splitting strength is in good agreement with the test values.

Study on Mechanical Behavior of Hollow-Core Slab Bridge with Pinned Reinforcement.

Joints connect prefabricated hollow-core slabs, the key elements of force transmission of hollow-core slab bridges. The joints are easily damaged, which affects the integrity and safety of the hollow-core slab bridge. This paper uses MIDAS FEA NX finite element analysis software to simulate the deep hinge joint segment model, comparing and analyzing the finite element simulation analysis results with the test results, and proposes the critical parameters of the hinge joint interface and concrete damage plasticity. Further, an assembled hollow slab bridge model is established to compare and analyze the force transfer performance of conventional and pinned reinforcement bridges and reveal the deep joint damage evolution process. The results showed that the hollow slab bridge damage appeared first at the hinge joint interface at the load location. Cracks in the joints can develop along the longitudinal and height directions, with the longitudinal crack length reaching 40% of the span. The vertical crack height can get the lower edge of the paving layer, increasing the distance from the load position, and the cracking height decreases symmetrically. Under an ultimate load, the hinge concrete of conventional reinforcement and pinned reinforcement hollow-core slab bridges showed significant damage in 30-70% and 40-60% of the span, respectively. Compared with the conventional reinforcement bridges, the cracking load and ultimate load of the pinned reinforcement bridges increase by 28.57% and 58.14%, respectively, and the relative deflection under 420 kN load reduces by 97.95%. The hollow slab bridges have improved the force performance and thus enhanced the integrity of the hollow-core slab bridges.

Modeling and robust quantitative control for AUV-tow-load system

This paper models a point-mass load tethered to a single autonomous underwater vehicle (AUV) and proposes a quantitative control strategy, which is able to drive the load to track the desired trajectory closely. The AUV-tow-load system is modeled as three connected subsystems: load position subsystem, cable direction subsystem, and AUV attitude subsystem. Improving on the current prescribed performance control methods, where the transient-state and steady-state tracking behaviors cannot be preassigned accurately, a quantitative controller is designed for the point-mass load position, achieving predefined tracking performance without violating user-defined quantitative indices including overshoot, convergence time, and steady-state accuracy. An uncertainties and disturbances estimator (UDE) is designed and incorporated into the control inputs to compensate for the effects of uncertain dynamics and external disturbances. Rigorous theoretical proof is presented, showing that all tracking errors converge to the neighborhood of zero with quantitatively designed tracking behaviors, obtaining uniformly ultimately boundedness. Simulation results are provided to validate the efficiency of the proposed method.

Out-of-plane dynamic instability of functionally graded porous circular arches reinforced by graphene platelets in thermal environment

This paper investigates out-of-plane dynamic instability for functionally graded porous (FGP) graphene platelets reinforced composites (GPLRC) circular shallow arches subjected to a radial periodic concentrated load in a thermal environment for the first time. Hamilton principle is employed to derive the differential equations of motion of the arches associated with out-of-plane displacements. The dynamic instability regions (DIR) with period 2T are determined by using Bolotin’s method and verified by finite element software ANSYS. The effects of uniform temperature difference,out-of-plane boundary condition, pore distribution mode, the weight fraction of graphene platelets (GPLs), GPLs dimension coefficients, and the location of the concentrated periodic load on the DIRs are comprehensively analyzed. The results show that higher temperature difference can weaken the dynamic stability of the arch. The load position has no influence on the boundary excitation frequency at the lowest point of the DIR but plays a negative impact on the area of the DIRs and a positive influence on the lowest value of the load. The parametric resonance of the arch is more likely to occur if the concentrated periodic load is located near the arch crown.

Turpentine as an Additive for Diesel Engines: Experimental Study on Pollutant Emissions and Engine Performance

The need for reducing fossil fuel consumption and greenhouse gas (GHG) emissions in internal combustion engines has raised the opportunity for the use of renewable energy sources. For the progressive replacement of fossil fuels like diesel, those derived from the sustainable management of forest resources may be a good option. In Portugal, pine trees (pinus pinaster) are among the most widely cultivated tree species. Turpentine can be extracted from their sap without harming the tree. Turpentine is known to be a good fuel with a lower viscosity than regular diesel but with a comparable caloric value, boiling point and ignition characteristics, although it is not widely used as a compression ignition fuel. Moreover, recent research has highlighted the possibility of substantially increasing the turpentine yield through biotechnology, bringing it closer to economic viability. The present study investigates the performance, pollutant emissions and fuel consumption of a 1.6 L four-cylinder direct-injection diesel engine operating with several blends of commercial diesel fuel and turpentine obtained from pine trees. The aim of this study was to assess whether it would be possible to maintain or even improve the performance, fuel consumption and GHG and pollutant emissions (HC, NOx, CO and PM) of the engine with the partial incorporation of this biofuel. Turpentine blends of up to 30% in substitution of regular diesel fuel were tested. The main novelties of the present work are related to (i) the careful testing of a still-insufficiently studied fuel that could gain economical attractiveness with the recent developments in yield improvement through biotechnology and (ii) the tests conducted under fixed engine load positions typical of road and highway conditions. The addition of this biofuel only slightly impacted the engine performance parameters. However, a slightly positive effect was observed in terms of torque, with an increase of up to 7.9% at low load for the 15T85D mixture and 6.8% at high load being observed. Power registered an increase of 9% for the 15T85D mixture at low speed and an increase of 5% for the 30T70D mixture at high speed when compared to the reference fuel (commercial diesel fuel). While the efficiency and fossil GHG emissions were improved with the incorporation of turpentine, it had a mixed effect on polluting emissions such as unburned hydrocarbons (HC) and smoke (PM) and a negative effect on nitrogen oxides (NOx). NOx emissions increased by 30% for high loads and 20% for low loads, mainly as an indirect effect of the improvement in the engine performance and not so much as a consequence of the marginally higher oxygen content of turpentine relative to commercial diesel fuel.