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This paper evaluates the effectiveness of similitude theory in predicting the draft of a rubber tire loader’s bucket during initial penetration. The work uses 1:16 and 1:8 scale models of an 18-t capacity load haul dump, scaled with the Buckingham Pi Theorem, to evaluate the prediction of draft and penetration under different operating and different dynamic conditions. The authors hypothesize that the observed relationships between draft and longitudinal penetration and the operating and dynamic conditions will hold true for an upscaled model. Similarly, the authors hypothesized that the results of experiments conducted with the smaller scaled model should predict the draft on an upscaled model. The results show that the relationships between draft and longitudinal penetration and operating and dynamic parameters are similar for both scaled models. Similarly, the draft on the upscaled model, predicted by using the experimental results of the small model, is similar to the measured draft on the upscaled model. The mean difference between the two is 1.71 N with 95% confidence interval of [-3.51, 6.93], which is very good given the average draft is approximately 330 N. Thus, the work indicates that both hypotheses are true for draft. However, the work shows that scaling muck pile particle sizes using the Buckingham Pi Theorem is not adequate to ensure good predictions of penetration. This work provides insights that will help design engineers to acquire useful data on scaled models and use it for various analyses on heavy machinery.

Coal is still a part of energy generation worldwide and has a significant role in the sustainable development of countries. The amount of shallow coal deposits is getting scarce, making efficient underground mining operations crucial for both local and global economies. In underground mining operations, longwall mining is a commonly utilized method to extract deep coal deposits. One of the leading engineering goals in longwall mining is increasing the efficiency of the system by investigating the effects of operational factors on equipment. This paper investigates the shearer performance for a longwall top coal caving operation by discrete event simulation that includes modeling the double-drum shearer, belt conveyors, stage loader, and armored face conveyors (AFC) to evaluate system performance by considering the amount of daily coal production of the shearer. As a result, the most influential factor on mine production is determined and a data-based framework is developed. This study suggests a framework for data collection, data analysis, and the interpretation of the operational data to evaluate the primary production unit’s performance. The models developed for the face coal extraction operations in a longwall top coal caving (LTCC) mine have a bi-directional cutting system and can be implemented in other operations readily.

The E. coli γ clamp loader is a pentameric complex of δ, δ′ and three γ subunits that opens and loads β-clamp proteins onto DNA in an ATP-dependent process essential for efficient DNA replication. ATP binding to the γ subunits promotes conformational changes that enable the clamp loader to bind and open the ring-shaped β-clamp homodimer. Here we report the nearly complete backbone and side-chain (1)H, (13)C and (15)N NMR resonance assignments of the 242-residue truncated γ subunit of the clamp loader complex, which includes the N-terminal mini (domain I) and lid (domain II) domains. This construct represents the nucleotide binding module in the clamp loader complex and provides a model system for studies of conformational rearrangements of the clamp loader induced by nucleotide binding.

This work evaluated the effect of bucket orientation and operating parameters on resistive forces and penetration for rubber tire loaders. The work used a 1:16 scale LHD model to test a rubber tire loader (RTL) bucket operating at different levels of tractive effort, speed, digging height, and rake angles in a full factorial design experiment. The work repeated the test on two different muck piles with different particle sizes and used generalized regression modeling to test the association of rake angle, tractive effort, speed, and digging height on penetration and resistive forces for RTL buckets. The results show that speed and tractive effort are more important in explaining RTL penetration and resistive forces than height above the floor and rake angle. Speed, tractive effort, and height above the floor are positively correlated to bucket penetration, whereas the rake angle is negatively correlated to penetration. Similarly, speed, tractive effort, rake angle, and height above the floor are all positively correlated to resistive forces incurred during initial penetration. The observation that the combined effect of speed and tractive effort is negatively correlated to penetration and resistive forces is a novel contribution that enhances our understanding of RTL loading. The results also show that the effect of speed, tractive effort, and height above the floor all change with changes in particle sizes. This work adds to the literature on the effect of rake angle, height above the floor, tractive effort, and speed on penetration and resistive forces for rubber tire loaders.

Recent studies have demonstrated that the power-cycling hydrodynamic mechanical (PCHM) transmission has excellent performance in improving power performance and fuel economy of a wheel loader. However, these results have been obtained by assuming that its speed ratio can always change continuously. Hence, this study first investigated the speed ratio of the transmission how to change when shifting from one gear to another. It was found that the concept of the PCHM transmission suggested in the literature is ineffective, even for a configuration with two gears in the gearbox. Then, the configuration of the PCHM transmission was developed as a different one to increase the torque multiplication capacity and efficiency of the transmission. A design method for this transmission is proposed to quantify its performances. The design method is based on a multi-objective optimization problem which is comprised of two objectives, seven design variables and eleven constraints. The relationships between average efficiency of the transmission and maximum tractive force of the vehicle and the seven transmission parameters are qualitatively examined. Results show that the performance of the transmission depends mainly on the number of transmission gears instead of on three parameters of the torque converter. The average efficiency is not sensitive to the maximum tractive force on a globally optimal Pareto front. The PCHM transmission with the new configuration can enable the average efficiency and the maximum tractive force to increase by 2.1 % and by 6.6 %, compared to that of the traditional hydrodynamic mechanical transmission, respectively.

This study applies image recognition technology to the shovel loading operation of a wheel loader for the first time. In the proposed method, the wheel loader can automatically select the corresponding engine power curve according to different identifiable materials, thus achieving intelligent energy saving. This study first analyzed the working resistance of the wheel loader, and the analysis results provided theoretical support to the energy-saving operation of the wheel loader. The shovel loading test was carried out for different materials. The test results validated the feasibility of intelligent energy-saving operation of the wheel loader based on identifiable materials. A neural network algorithm based on material identification model was then built and verified, whose material identification rate was 92 %. The model was used as the carrier, and the wheel loader-operating characteristics were considered in view of the existing engine energy-saving mode. Finally, the boom cylinder pressure and bucket angle were used as feedback to future discussion about the intelligent energy-saving operation of the wheel loader. The basic conditions for subsequent designs of wheel loaders are provided.

The automatic transmission of earthmoving machinery generally has problems of shifting shock and poor control robustness. Low-frequency high-energy random loads and large-space model uncertainties are the main causes of these problems. Therefore, we considered a type of wheel loader automatic transmission as the research object and propose a robust control method for the shifting inertia phase of the earthmoving machinery automatic transmission. The control method includes a robust controller Kb, a disturbance compensation controller Kd and a feedforward compensator Kf. The robust controller Kb is designed by μ synthesis method to resist the uncertainties of parameters and structure and guarantee the output speed to track the reference input. A load dynamic estimation method for random disturbance load of automatic transmission is proposed, which improves the compensation effect of disturbance compensation controller Kd. The feedforward compensator Kf is used to eliminate the influence of the reference input on the system. The above control methods were applied to the whole machine simulation platform of a certain type of wheel loader, and the random disturbance load of the measured under real working conditions was taken as input load. Under the conditions of no-load, half-load and full load, the control method has good smoothness and strong robustness. This paper has reference value for solving the inertial phase shift robust control of transmission under random disturbance load.

The lifecycle costs of systems are moving more and more into the focus of machine manufacturers to ensure competitive edges and strengthen customer relations. This results in development goals such as higher avail-ability, maintenance intervals according to requirements, and minimized outages and downtime costs. Mobile machines are subjected to loads which, occasionally, are characterized by the working task, the environmental boundary conditions and the operator. In practical use of mobile machines, some operators are not very experienced in handling a machine, for instance when using machines in the construction industry. In these cases, performing the job enjoys priority over the state of a machine and its service life. The situation is aggravated by the fact that entrepreneurs, especially in the fields of add-on and special machines, prefer to use leased vehicles, thus the operators are confronted with new machines all the time. Because of the individual control characteristics of operators, this results in permanently changing sequences of motions and load situations for the machine. The high loads occur frequently in operation and can lead to premature failure of a machine. As a result, it will be impossible to continue the activities needed to fulfil the working task and, on the other hand, it may be necessary to repair or even scrap a machine and buy a new one. Both consequences result in economic harm for the machine owner. In the many cases it is difficult to influence the working task and the environmental conditions established by the environment in the light of the objective, e.g. to achieve the required result while simultaneously minimizing component load. On the other hand, operation of a vehicle offers a more evident degree of freedom in minimizing damage. Vehicle control systems adapted to external conditions and the working task, which make operators and vehicles perform under operating conditions less prone to result in damage, thus can reduce loads and defects and, consequently, also reduce operating and maintenance costs. The final conse-quence is a higher availability of the machines. A control system of this kind requires knowledge of current loads and load-bearing capabilities of components of a mobile machine. Developing a method of real-time load determination as shown for the boom of a wheel loader therefore is the content of this article.

The shift scheduling system of the transmission has an important effect on the dynamic and economic performance of hybrid vehicles. In this work, shift scheduling strategies are developed for parallel hybrid construction vehicles. The effect of power distribution and direction on shift characteristics of the parallel hybrid vehicle with operating loads is evaluated, which must be considered for optimal shift control. A power distribution factor is defined to accurately describe the power distribution and direction in various parallel hybrid systems. This paper proposes a Levenberg-Marquardt algorithm optimized neural network shift scheduling strategy. The methodology contains two objective functions, it is a dynamic combination of a dynamic shift schedule for optimal vehicle acceleration, and an energy-efficient shift schedule for optimal powertrain efficiency. The study is performed on a test bench under typical operating conditions of a wheel loader. The experimental results show that the proposed strategies offer effective and competitive shift performance.

The capacity trend and characteristics of the torque converter (TC) are the basis for ensuring that a power reflux hydrodynamic transmission system (PRHTS) is well matched to the engine it is paired with. This paper proposes a design method for matching a PRHTS with a given engine. First, using the working principles of the PRHTS, the influence of a TC with different capacity trends on matching is analyzed, revealing that an impervious capacity-trend TC can ensure good matching performance. Then, by considering the working characteristics of a capacity adjustment device that can change the capacity coefficient of the PRHTS, a method for obtaining the range of TC capacity coefficient values is proposed. This method determines the range of TC capacity coefficients by finding the speed ratio and capacity coefficient that matches the maximum torque and optimal operating points of the engine. After adopting the matching design method proposed in this paper and upon comparison with the traditional hydrodynamic transmission system, the PRHTS is noted to improve the matching performance as well as the dynamic and economic performance of the wheel loader.

We conducted the preliminary time studies of clear-cutting operations using a small-scale cable logging system in 62- and 107-year-old, gently and moderately sloping Japanese cypress forests. The cycle times, productivities, and costs were compared to examine the effects of extending the cutting age. The operation system included the use of a chainsaw for felling, a tower yarder for yarding, a grapple loader for bunching and piling, and a processor. For some 107-year-old trees, a chainsaw was also used for delimbing operations because of the larger branches. The productivities of felling and processing operations did not decline beyond a certain stem volume even with chainsaw felling and the use of a small-sized processor (6.7 t). The average cycle time of yarding operations in the 107-year-old forest was longer, but the productivity was higher compared to the 62-year-old forest, owing to larger volumes. Although geography and stand conditions differed, productivity and costs of the operation systems were similar even with larger volumes and using small-sized machines. The costs of the operation systems were JPY 2088/m3 and JPY 2307/m3 in the 107- and 62-year-old forests, respectively. The costs were slightly higher than those with larger ground based machines. A small-scale cable logging system, on a relatively gentle slope with larger volumes is an option for low-cost, clear-cutting operations in small-scale forestry.

An important issue in developing a virtual simulation environment for a wheel loader is capturing the interaction force between the bucket and soil during excavation. In this work, we review several important studies on fundamental earthmoving equations (FEE) and confirm that discontinuity of soil force occurs when soil is loaded with a large terrain angle using a soil model based on traditional FEE for a wheel loader. This discontinuity is removed by recalculating the external friction angle to satisfy the force equilibrium condition under the assumption that the combined net normal and frictional force is zero in a certain condition. Comparison of an actual test with an inverse dynamic simulation using measured data confirms that the soil model proposed in this study is sufficient for estimating the external force transferred to the structure during actual operation. This soil force model can be used for durability and performance assessments in the initial design of wheel loaders.

The paper defines the directed digging force as a criterion for the optimal synthesis of loader mechanisms. The directed digging force is defined on the basis of the following: boundary digging forces permitted by the stability of a loader, boundary digging forces enabled by loader mechanisms, and factors related to the digging position in the working range of a loader and the directions and senses of activity of the possible digging resistance. A general mathematical model and applicative software are defined for the purpose of determining the directed digging force. The developed software is used to perform a comparative analysis of boundary digging forces and determine the defined directed digging force for two loader models with the same mass (around 15,000 kg with the bucket capacity of 2.7 m3) with the identical parameters of the kinematic chain but with different parameters of the loader mechanisms. The results of the analysis presented in the paper show that the defined directed digging force can be used to assess the digging efficiency of already created loader models, but also as an optimization criterion in the synthesis of loader mechanisms in new models of loaders and other mobile machines.

A loader is a construction machine to upload soil into trucks or to transport those materials. As a kind of loaders, a wheel-loader, which is driven by wheels, has been widely used. Since a wheel-loader with an automatic transmission operates in the adverse environments such as constructions sites, the shift quality has not been addressed as a main research topic. However, the necessary for researches to improve the shift quality of automatic transmission raised to develop control technology for operator’s convenience. In this study, a wheel-loader’s power train with an automatic transmission was analytically modeled and then the shift quality was analyzed based on power train modeling. An analytical model of wheel-loader’s power train is verified by comparing experimental and simulated results under the same operational conditions. Since the shift performance is affected by the pressure in clutch piston, current profile of a proportional pressure control valve to control the automatic transmission was varied for the simulation verification. In the simulations, it was analyzed in terms of shift performance in each stage of fast filling, take-over and clutch slippage, and clutch slippage time. Finally, relative amplitude of jerk is used in order to decide the regular shift performance.

Many applications are built upon private algorithms, and executing them in untrusted, remote environments poses confidentiality issues. To some extent, these problems can be addressed by ensuring the use of secure hardware in the execution environment; however, an insecure software-stack can only provide limited algorithm secrecy. This paper aims to address this problem, by exploring the components of the Trusted Computing Base (TCB) in hardware-supported enclaves. First, we provide a taxonomy and give an extensive understanding of trade-offs during secure enclave development. Next, we present a case study on existing secret-code execution frameworks; which have bad TCB design due to processing secrets with commodity software in enclaves. This increased attack surface introduces additional footprints on memory that breaks the confidentiality guarantees; as a result, the private algorithms are leaked. Finally, we propose an alternative approach for remote secret-code execution of private algorithms. Our solution removes the potentially untrusted commodity software from the TCB and provides a minimal loader for secret-code execution. Based on our new enclave development paradigm, we demonstrate three industrial templates for cloud applications: ① computational power as a service, ② algorithm querying as a service, and ③ data querying as a service.

When a system’s performance is inadequate, the concept of availability importance can be used to improve it. The availability of an item depends on the combined aspects of its reliability and maintainability. In a system consisting of many subsystems, the availability of some subsystems is more important to system performance than others. The availability measure determines the priority of availability across subsystems. Most researchers only consider operation time and ignore the influence of the operating environment; therefore, their estimations are not accurate enough. In contrast to previous research, we focus on the influence of the operating environment on the system/subsystem’s characteristics with a view to prioritizing them based on the importance of availability. The paper considers part of the mining fleet system of Sungun copper mine, including the wagon drill, loader, bulldozer, and dump truck subsystems. We identify an ordered list of possibilities for availability improvement and suggest changes or remedial actions for each item to either reduce its failure rate or reduce the time required to repair it.

The working mechanism is an important part of a wheel loader. It is used to accomplish the shoveling, loading, lifting, and dumping tasks. Usually, the working mechanism is a Z-bar linkage and the dimensional design of the linkage directly affects the loader’s service performance, such as dumping clearance and dumping height. As there are many other performance indexes and various field requirements for the loader, comprehensive optimum, and adaptable design methodology with full-parameterized kinematic model attracts engineers’ research interests. Focusing on the multi-objective and multi-variable problems, this paper firstly establishes an accurate and simplified kinematic model of the Z-bar linkage with deduced expression of the basic parameters, and then investigates the performance indexes including mechanism transmission ratio, lifting stationary, dumping angle in any position, bucket flat setting, and extreme transmission angle, etc. With the full-parameterized kinematic model and the optimum algorithm, modified complex method, a comprehensive and adaptable design platform is built to solve the multi-objective and multi-variable problems of the Z-bar linkage. A case study with two optimization schemes as “full variables design” and “partial variable design” is conducted. The simulation results show that both schemes are better than the original one. The methodology and platform in this paper are of importance in generating user requirement oriented linkage design schemes with enough consideration and optimization of multiple performance indexes.

This paper describes an investigation of energy efficiency by applying an advanced powertrain system in a conventional wheel loader. A conventional powertrain of a wheel loader consists of an engine, torque converter and transmission. A torque converter in a conventional system generally causes a significant amount of energy loss, as determined by analyzing energy flow based on V-pattern working. To prevent energy loss in a torque converter, Automated manual transmission (AMT) was proposed and modeled in this paper as an advanced powertrain. A wheel loader based on AMT does not need to use a torque converter since the single clutch system is used between the engine and transmission with subsystems of engine controller, clutch actuator and controller. A simplified single clutch system and controller were constructed for V-pattern working of a wheel loader. Additionally, a PI-controller was used as a control algorithm for engine speed control to prevent energy loss while the clutch is not engaged. All simulation models have been constructed in the Matlab/ Simulink environment, and simulation studies were conducted by using a simulation model of a wheel loader with a driver model based on V-pattern working. Simulation results of the AMT-based wheel loader were analyzed by comparison with the results of the torque converter-based wheel loader, and the results show that the AMT-based wheel loader is more energy efficient than the conventional wheel loader.

The pneumatic transfer system (PTS) of the Jožef Stefan Institute’s TRIGA Mark II research reactor was modernized. The main goals of the PTS’s renewal were to improve the overall quality of the irradiations, to increase the level of safety and to improve the timing precision. To lower the costs and to facilitate the licensing process, this upgrade was made with the minimum possible intervention with respect to the existing tubing connections. The upgrade involves only two new mechanical components: a terminal station and an automated capsule loader. A similar solution can be applied to any TRIGA-type PTS.

This paper presents a wheel loader simulation model, validation results and energy flow analysis. The developed simulation model will facilitate the performance evaluation and optimization process in the development stage of a prototype wheel loader. The wheel loader simulation model consists of mechanical and hydraulic powertrain model, multi-body dynamic model and working part dynamic model. The multi-body dynamic model is simplified since the effect of pitch and roll motion of the wheel loader on the energy flow of the powertrain and hydraulic actuator systems is insignificant, a simplified planar model for the dynamic vehicle is good enough for the objective of this study. Every component is modeled and integrated in a simulation package developed using Matlab/Simulink. The simulation model has been validated using experiment data and the validation results show that it effectively represents the actual dynamic characteristic of the target wheel loader. The verified simulation model will be used as a virtual platform to evaluate the performance of alternative powertrain models such as a dual-clutch transmission and hydrostatic transmission. An advanced control system can also be implemented and evaluated using the virtual platform.

The gear measuring test-rig with close power is widely used in gear transmission test. In the gear measuring test-rig with close power, the motor is used to compensate closed power loss and the loader provides the load torque for the whole closed loop. Usually, the installation position of motor and loader has not been paid enough attention; however, the improper installation position will cause extra energy loss. Therefore, the effect of installation position of motor and loader on energy loss of gear measuring test-rig with close power is studied in this paper. Firstly, the judgment rule of close power flow is introduced. Secondly, the possible installation position of the motor and the loader is analyzed, and the supplementary power and torque provided by motor are calculated, respectively. By comparison, when the installation position of motor and loader is on the same axis, the supplementary power and torque provided by motor are minimum and then the energy loss of test-rig is reduced. Finally, the corresponding simulation analysis, test verification and application are given.

Coal seams that dip more than 15° are classified as steeply inclined in Indian mining context. Mining of steeply inclined seams poses variety of problems starting from strata control to problems related to efficient mechanisation. Sawang-C seam of Govindpur Underground Project of Central Coalfields Limited is one such seam. Presently, the seam is being developed on bord and pillar method of mining, and the blasted coal is loaded manually into tubs using hand shovel and basket. In order to mechanise the loading operation, technical feasibility of formation of rhombus pillars and deployment of side discharge loader (SDL) are investigated along with design of supports from the point of view of roadway stability. This paper thus seeks to address the technical feasibility of deployment of Side Discharge Loader in a 1.7–2.2-m thin seam inclined at 16° if developed with rhombus pillars and to suggest suitable and adequate support system for such workings.

Loading and haulage costs make up the majority of the expenses—almost half of its total costs at many mines. At many mines, loading and haulage costs make up the majority of the expenses—almost half of its total costs, in fact. Many researchers believe that the properties of fragmented rock are one of the most important factors that affect the productivity of loading machines. The purpose of this paper is to study the effects of fragmented rock properties on the penetration rate of a loader’s bucket as one of the parameters of loading productivity. The study will be done using a simulated loader in the laboratory. For the study, 25 samples of fragmented rock with previously defined Rosin–Rammler’s size-distribution function, including the defined mean particle size (d50) and uniformity index (n), were built. Then, bulk-specific gravity and angle of repose of the samples were measured using standard laboratory tests. The relation of n and d50 and the measured properties of the samples with each other and with the penetration rate of the loader’s bucket were analysed. The results showed high correlation between pre-determined size distribution parameters and the measured properties of fragmented rock, including bulk-specific gravity and angle of repose. Also, the penetration rate is inversely correlated to the uniformity index, the angle of repose, and consequently, internal friction angle. And, it is in direct correlation with the mean particle size of the fragmented rocks and bulk specific gravity. It is obvious from the results that uniformity has more effect on the penetration rate than the mean particle size does.

Compound closed-loop mechanism methodology is proposed to model the wheel loader front-end kinematics for simulating the mechanism motion in a dynamic environment. For the numerical modeling purpose, the mechanism is considered as consisting of three vector loops connected by the joint angles or displacements. Each vector loop is formulated as time-dependent ordinary differential equations (ODEs). The simulations cover the numerical solutions of the forward and reverse kinematics differential equations. The consistency error check approach is employed to validate the simulation. A case study is presented to demonstrate the reverse kinematics simulation of the compound mechanism model in Simulink environment, which includes the user-defined program, numerical solution, and error analysis. The displacement-time variations of two driving cylinders are obtained with the inputs of the lift and rotation bucket accelerations. The simulation is validated with the numerical analysis of the error results. This research provides a significant method to simulate the wheel loader motion for wide-ranging engineering application.

The purpose of this study was to investigate the method of residual capacity estimation for lead–acid batteries used in automobiles. First, relation charts for the internal resistances of a battery at various load currents to residual capacity percentages were established, and the relation charts for all load currents were then combined to obtain the corresponding residual capacity by calculating medians. The experimental equipment included lead–acid batteries for automobiles, an electronic loader, an internal resistance tester, and test cables. The experimental procedures were discharging the battery with the electronic loader, using the internal resistance tester to record the internal resistance, voltage, and temperature of the battery, and then transmitting the data to a computer via the test cables for analysis. The experiment obtained nine sets of data, which were recorded in Excel and illustrated using charts. The medians obtained from combining the internal resistance with the residual capacity percentages were used to generate the relation charts for the internal resistances at various load currents to the residual capacity percentages. Finally, 60 Ah was used as the normal capacity to estimate the residual capacity discharging time. Furthermore, a curve-fitting approach for determining the relation equation between internal resistances and capacities was used to replace the table look-up method for residual capacity estimation. The results revealed that the estimation errors after correction were acceptable.

We investigated forest road networks and forestry operations before and after mechanization on aggregated forestry operation sites. We developed equations to estimate densities of road networks with average slope angles, operational efficiency of bunching operations with road network density, and average forwarding distances with operation site areas. Subsequently, we analyzed the effects of aggregating forests, establishing forest road networks, and mechanization on operational efficiency and costs. Six ha proved to be an appropriate operation site area with minimum operation expenses. The operation site areas of the forest owners’ cooperative in this region aggregated approximately 6 ha and the cooperative conducted forestry operations on aggregated sites. Therefore, 6 ha would be an appropriate operation site area in this region. Regarding road network density, higher-density road networks increased operational expenses due to the higher direct operational expenses of strip road establishment. Therefore, road network density should be reduced to approximately 200 m·ha−1 within average pre-yarding distances on which a grapple loader could conduct bunching without winching. With larger stem volumes a larger reduction in operational expenses occurred for the mechanized operation system compared to the conventional operation system. However, with smaller stem volumes, the operational expenses for the mechanized operation system were higher than for the conventional operation system. Therefore, the appropriate operation system and machine sizes should be determined based on stem volumes.

The operation mechanism is generally considered as a key component of a wheel loader. Its working performance has great influence on the service life, stability, efficiency and economy of the loader. This paper establishes a mathematical model of Z-bar loader mechanism in polar coordinate with four-bar linkage and six-bar Watt linkage synthesis, investigates the working performance, such as mechanism transmission ratio, carry stability, parallelism, dumping in any position, bucket flat setting, maximum dig depth, extreme transmission angle and so on. Then we explore new design methods of joint-position of Z-bar loader linkage between tilt cylinder and loader frame to perfect some of the performance. A new method, comprehensive genetic algorithm, is presented to optimize non-linear equation with multi-constraints, and the results improve the multidisciplinary performance. Furthermore, a virtual prototype of the working mechanism is modeled to simulate and verify the optimization results.

Modular products can present many effectiveness scenarios in its product life cycle. Ideally, these scenarios can be achieved simultaneously. However, due to the diverse objectives of different phases, different module forms are required, and accordingly, conflicts may occur. Traditional modular design techniques have been motivated towards delivering variety, but with little incentive for effectiveness of modules per se. To reduce the conflicts, and to maximize the effectiveness of modules throughout product life cycle as much as possible, this paper put forward an effectiveness-driven modular design method which takes all effectiveness scenarios into consideration and balances the granularity and composition of modules among all possible forms during the clustering process. As the basis of effectiveness-driven modular design, a product descriptive model composed of components, interaction attributes, and liaison structure is proposed. Then, to cluster components according to different effectiveness scenarios at different phases, a quantitative split method for liaison structure is proposed. Furthermore, to maximize the effectiveness of the modules, three aggregation rules are put forward. A case study of wheel loader modular design is reported. Results and analyses reveal that the effectiveness-driven modular design excels in supporting modular design for life cycle.

The paper proposes a standardized image-processing procedure with the use of sieve analysis results for calibration which is utilized to measure the size distribution of fragmentation at Sungun mine. Through this procedure, a number of 19 bench blasting in various levels have been initially selected as the target of the study for each, multiple photos were taken immediately after blast from suitable perspectives and locations of the muckpiles surfaces. The number of image sampling was chosen adequately high to achieve further reliability of the whole photography procedure. Then fragments of each muckpile were separately mixed by a loader, where another image sampling from these new muckpiles, bucket of loaders, and haulage trucks was performed. For the purpose of sieve analysis, seven sieves with the mesh sizes between 1.27 cm (0.5 in) and 25.4 cm (10 in) were designed, manufactured, and then installed at Sungun semi-industrial laboratory. Additionally, three mass samples of the mixed fragments were randomly chosen among the 19 muckpiles for sieving. During image analysis stage, “sieve shift” and “mass power” factors, required to obtain standardized size distribution, were precisely assigned when the results obtained by the image analysis software was in accordance with the sieving results. In order to validate the reliability of the image processing, a comparative analysis of the achieved results was made with the results of the original Kuz–Ram model [Cunningham (1983) The Kuz–Ram model for prediction of fragmentation from blasting. In: Proceedings of the first international symposium on rock fragmentation by blasting, Lulea, Sweden, pp 439–454]. Finally, the image-processing procedure was found to be more efficient, with results close-matched to the real results of the sieve analysis.

This paper presents the dynamic analysis and kinematic parameter optimization of a coupled linkage system for the purpose of employing the system in construction industry. So far, the kinematic optimization of wheel loaders was approached heuristically rather than utilizing elaborate theoretical examinations due to the complexity of coupled linkage structures. The results of the theoretical analysis and kinematic parameter optimization are presented in this paper. A wheel loader with Z-bar linkage was analyzed. For a given end-effector path, the linkage system was optimized to carry out effective motion while exhibiting minimum power consumption during operation. A modified principle of reduced system was applied in order to execute the dynamics analysis of the coupled linkage system. As a result, an optimal Z-bar linkage structure and a distribution of power consumption within the given conditions were obtained.

Time equations are derived for felling with chainsaw, skidding with cable wheeled skidder, loading with grapple hydraulic loader and trucking of logs within a cut-to-length harvesting method. The continuous time study method was applied to collect data for felling, skidding, loading and a transportation model. Multiple regression analysis via SPSS software was applied to develop the time models. Felling time was found to be highly dependent on diameter at breast height. Skidding distance, winching distance, slope of the trail and piece volume were significant variables for the skidding time prediction model. The loading time model was developed considering piece volume. Transportation distance and load volume were used as independent variables in modeling the transportation time. The net production of felling was estimated at 12 trees/h (56.65 m3/h). The net production rates for skidding, loading and traveling averaged 18.51, 41.90 and 3.32 m3/h respectively. The total cost of harvesting from stand to mill was estimated 19.70 €/m3. The skidding phase was the most expensive component of the cut-to-length method. The bucking and delimbing components were less costly than the other logging phases. The results of this study can be used for harvesting planning and productivity optimization.

The cane growing area along the Nile valley in Upper Egypt has expanded. Most of farmer holdings are small, typically ranging from 0.5 to 1 hectare. Cane delivery schedules and consequently harvesting dates mainly depend on the delivery allocation and the date of harvest last season. The mill administration assigns a transport vehicle (main vehicle) for each farmer according to the schedule. Farmer/s harvest and transport cane from inside field/s (using a tractor-pulled-trailers) to temporary storage sites at which the main vehicle/s are loaded. Loader efficiency can be low due to time losses associated with travel from one storage site to another. To achieve reasonable efficiency of the loader, storage sites may be amalgamated allowing greater utilisation of loaders. This procedure may increase the infield transport distance which may reduce the rate of cane supply from fields, thus contributing to increased cane delivery delay. Farmers may have to transport a part of the main vehicle load to the storage site the previous day to secure continuous operation of the loader. In this study, loader efficiency, loading rate, the percentage of main vehicle/s load/s delayed more than 24 h and cane collection efficiency were studied. In most cases, one main vehicle was assigned to each farmer, where a trailer pulled by tractor was used to transfer cane from inside the field to the storage area. Results showed that total efficiency of the loader was 75% in case of loading lorries in a large storage area and 81% in case of railway wagons loaded at a station. Average total efficiency of the loader was 61% when loading decauvelle wagons distributed in several storage areas within the same production region. Efficiency of loading tractor trailers in the field was 54%. Maximum efficiency was observed to be achieved if the loader works for the full operational day in one storage area. Cane collection efficiency was variable for the variable operating conditions. The percent of cane delayed more than 24 h was also estimated. Large temporary storage areas at which lorries are loaded with cane, and cane loading stations for railway wagons may represent more optimal conditions for loader operation. The paper discusses the efficiency of loader operation under a range of variable conditions, and related cane delivery delay. The results highlight the role of loader operation efficiency as a factor determining the adoption of mechanical loading of sugarcane. Recommendations for proper operation of cane loader are suggested.

The paper describes calculation of excavation and loading machinery service capacity, considering in more details the influence of mine technical factors.

The new-developed procedure to calculate engineering capacity of excavation-and-loading machines more tightly relates the machine performance and the rock properties and fullest includes the effect of mine technical factors.

Based on the analysis of the known calculation methods for the capacity of shovels and loaders at open cast mines, the authors have shown the expediency of the development and computer realization of a procedure for planning the shovel and loader capacity at open cast mines thus increasing the open cast mine planning efficiency due to a large number of optimization parameters, high operational efficiency and accuracy of the calculations.

3-dimensional (3D) modeling approach of the working linkage of load-haul-dump (LHD) loader has been presented to implement 3D computer aided design (CAD) and manufacture. The modeling approach is described in detail with application examples. The major issues in implementing modeling are discussed. Research work is focused on integration of basic modeling operations in the HELIX design system with modeling methods proposed in this work to achieve part modeling, assembly modeling, and assembly analysis of the working linkage. Part modeling operations in the HELIX design system and proposed compound modeling method are used together to design the parts in 3-dimensions. Assembly modeling operations in the HELIX design system and proposed feature-based modeling and assembly method from top to bottom have been integrated to assembly parts into an assembly tree structure in 3-dimensions. Assembly analysis operations in the HELIX design system have been proposed to find out the geometric connection, express the spatial dimension and make the interference check in the assembly model. This approach can be used for all kinds of 3D modeling of the working linkage of LHD loader.

Sliding clamps are loaded onto DNA by ATP-dependent clamp loader complexes. A recent crystal structure of a clamp loader-clamp complex suggested an unexpected mechanism for DNA recognition, in which the ATPase subunits of the loader spiral around primed DNA. We report the results of fluorescence-based assays that probe the mechanism of the Escherichia coli clamp loader and show that conserved residues clustered within the inner surface of the modeled clamp loader spiral are critical for DNA recognition, DNA-dependent ATPase activity and clamp release. Duplex DNA with a 5'-overhang single-stranded region (corresponding to correctly primed DNA) stimulates clamp release, as does blunt-ended duplex DNA, whereas duplex DNA with a 3' overhang and single-stranded DNA are ineffective. These results provide evidence for the recognition of DNA within an inner chamber formed by the spiral organization of the ATPase domains of the clamp loader.

The object under investigation is a system of loader-haul-dumper teleguidance performed by operators from the surface. The GPSS/H-language simulation model represents a multiple-service close machine system with three states: load control from the surface, automotion to place of dumping and backward, and wait state until operator is disengaged. The dependence of operator workload and machine downtime on the machine number and random time of technological operations are presented. The model may be used to choose load strategy, to estimate downtime at various haulage distances, and to investigate selective mineral mining.

The possibility is considered for using the multilayer perceptron and radial-function neural networks for predicting the load on excavating machines. The analysis of stochastic change in the cutting force is required to study the processes of mineral excavation by the combined cutter loader. The methods based on the fuzzy expert systems are proposed for controlling these processes in real time.

Recent papers of Copas (1995), Hjort and Jones (1996) and Loader (1996) have developed closely related methods for “local likelihood” density estimation. In various places, however, a more “simple-minded” and explicit analogue of local polynomial fitting in regression has been proposed for density estimation. By introducing the usual kind of binning procedure into Hjor and Jones' method, it is shown how the more and less sophisticated versions can be reconciled. Also, we attempt to understand better the role of the attractive subclass of local likelihood methodology proposed by Loader. Finally, we look at a further subset of methods and make some theoretical comparisons between members of this class.

It is frequently desirable to measure reaction time independently of movement time. The Hormann and Allen (1987) millisecond timer for the Commodore 64 or 128 can be modified to allow the measurement of reaction time with minimal movement time. A BASIC loader is provided for a keyboard version and an external switch version of the modified timer. Machine language code is provided for use with MONITOR, the machine language utility built into the Commodore 128.

Structures of the clamp loader–clamp complex reveal that nature uses machined parts in the form of a spiral scaffold (the clamp loader) to thread a circlet (the clamp) on a helix of DNA. The scaffold is then replaced by an interpretive copying machine, the polymerase, to eventually generate the replisome for DNA replication.

Among the numerous molecular machines involved in the process of DNA replication are the ring-shaped sliding clamp and the clamp loader. Intriguing structural details of their interaction are now revealed.

In process flows of concentration mills, various accumulating units, such as multisection storage units, are frequently used; these units are loaded with a mobile loader and unloaded through a system of dosage units at the base of the unit into the collection conveyor. The loading and unloading process can be controlled to have both a stabilizing effect on ore quality homogenization and the destabilizing effect of segregation on quality characteristics. This article examines a regime where a periodically changing ore reserve is created in each section of the container and control of the operation of a container loaded by a mobile loader is considered as a simultaneous problem of averaging the quality characteristics of ore in each of the sections of the container by pulsating the level in it and the averaging of the overall flow in the collection conveyor as a result of time shifts in the loading of each of the container sections. Ore flow quality variance was averaged over a period of time on a collection conveyor as a function of the loaded portion size. Results consider intersectional and intrasectional averaging and segregation.