Simulation analysis of the impact of container wagon pin configuration on the train loading time in the intermodal terminal

The article presents the issues of a container train loading at the land intermodal terminal. This issue was considered from the point of view of the distance covered by the loading devices and the duration of loading works, which was influenced by the arrangement of containers on the storage yard and the configuration of pins on the wagons. The conducted research was dictated by the small number of publications on loading an intermodal train, especially from the point of view of pin configuration on wagons. The vast majority of the literature is devoted in this field to marine intermodal terminals, which operating characteristics are different from inland terminals. The importance of this problem resulting from the growing turnover of containers transported by rail transport was also pointed out. The systematic increase of this type of transport and the depletion of the intermodal services' operating capability makes it necessary to improve the train loading process. For the purposes of the research, the issues of containers of various sizes loading onto wagons planning with various pin configurations were presented. A literature review was carried out in the field of train loading methods and strategies. A mathematical model was developed for the decision situation under consideration. The equations defining the most important elements of the considered problem were presented in the general form. This model was implemented in the FlexSim simulation environment. The constructed simulation model was used to develop 12 variants of the approach to an intermodal train loading. The train loading tests were performed both for the random arrangement of containers on the storage yard and for the random arrangement of pins on the wagons. The obtained results made it possible to determine how the knowledge of the arrangement of pins on the wagons influences the planning of train loading and increases the efficiency of loading devices.

Micro versus Macro Shear Bond Strength Testing of Dentin-Composite Interface Using Chisel and Wireloop Loading Techniques

Shear bond strength (SBS) testing is a commonly used method for evaluating different dental adhesive systems. Failure mode analysis provides valuable information for better interpretation of bond strength results. The aim of this study was to evaluate the influence of specimen dimension and loading technique on shear bond strength and failure mode results. Eighty macro and micro flowable composite cylindrical specimens of 1.8 and 0.8 mm diameter, respectively, and 1.5 mm length were bonded to dentinal substrate. Four study groups were created (n = 20): Macroshear wireloop, Gp1; Microshear wireloop, Gp2; Macroshear chisel, Gp3; and Microshear chisel, Gp4. They were tested for SBS using chisel and wireloop loading devices followed by failure mode analysis using digital microscopy and SEM. Two- and one-way ANOVA were used to compare stress at failure values of different groups while the Kruskal–Wallis test was used to compare between failure modes of the tested groups. Gp4 recorded the highest mean stress at failure 54.1 ± 14.1 MPa, and the highest percentage of adhesive failure in relation to the other groups. Specimen dimension and loading technique are important parameters influencing the results of shear bond strength. Micro-sized specimens and chisel loading are recommended for shear testing.

On the question of the appointment of separate parameters of the roadheaders gathering-stars loading organs

Most modern roadheaders of selective action are equipped with loading devices with gathering-stars, which have a simpler drive design and increased reliability. As a result of the experimental studies carried out at SRSPU (NPI), it was found that under certain conditions, it is possible to transfer large lump material of a pile into a fluidized state, which reduces the energy consumption of material loading. An increase in the number of beams of the gathering-stars reduces the influence of the other parameters of the loader. Analysis of the process of interaction of the gathering-star’s beam with the receiving conveyor’s side edge to avoid jamming of the picking gathering-star by a lump of material with the implementation of high dynamic loads, it is necessary to set the gathering-beams at an angle of at least 60 degrees against rotation.

Effect of the Mechanical Load on the Carbonation of Concrete: A Review of the Underlying Mechanisms, Test Methods, and Results

As one of the major causes of concrete deterioration, the carbonation of concrete has been widely investigated over recent decades. In recent years, the effect of mechanical load on carbonation has started to attract more attention. The load-induced variations in crack pattern and pore structure have a significant influence on CO2 transport which determines the carbonation rate. With different types of load, the number, orientation, and position of the induced cracks can be different, which will lead to different carbonation patterns. In this review paper, the carbonation in cracked and stress-damaged concrete is discussed first. Then, literature about the effect of sustained load during carbonation is compared in terms of load type and load level. Finally, the advantages and disadvantages of possible test methods for investigating the effect of sustained load on carbonation are discussed with respect to loading devices, load compensation, and specimen size.

Hydrostatic Pressure Modulates Intervertebral Disc Cell Survival and Extracellular Matrix Homeostasis via Regulating Hippo-YAP/TAZ Pathway

Established studies proved that hydrostatic pressure had multiple effects on the biological behavior of the intervertebral disc (IVD). However, the conclusions of the previous studies were inconsistent, due to the difference in hydrostatic loading devices and observing methods used in these studies. The current study is aimed at investigating the role of dynamic hydrostatic pressure in regulating biological behavior of the notochordal nucleus pulposus (NP) and fibrocartilaginous inner annulus fibrosus (AF) and its possible mechanism using our novel self-developed hydrostatic pressure bioreactor. The differences in the biological behavior of the rabbit IVD tissues under different degree of hydrostatic pressure were evaluated via histological analysis. Results revealed that low-loading dynamic hydrostatic pressure was beneficial for cell survival and extracellular matrix (ECM) homeostasis in notochordal NP and fibrocartilaginous inner AF via upregulating N-cadherin (N-CDH) and integrin β1. In comparison, high-magnitude dynamic hydrostatic pressure aggravated the breakdown of ECM homeostasis in NP and inner AF via enhancing the Hippo-YAP/TAZ pathway-mediated cell apoptosis. Moreover, inner AF exhibited greater tolerance to physiological medium-loading degree of hydrostatic pressure than notochordal NP. The potential mechanism was related to the differential expression of mechanosensing factors in notochordal NP and fibrocartilaginous inner AF, which affects the fate of the cells under hydrostatic pressure. Our findings may provide a better understanding of the regulatory role of hydrostatic pressure on the cellular fate commitment and matrix metabolism of the IVD and more substantial evidence for using hydrostatic pressure bioreactor in exploring the IVD degeneration mechanism as well as regeneration strategies.

Increase the functionality of vibration feeders with electromagnetic vibration

Under modern conditions vibrating hopper feeders with electromagnetic drive are irreplaceable when it comes to production processes in mechanical engineering and instrument making optimization processes. They are used to download small, medium or miniature details to automated technological equipment, such as automatic machines, automatic lines and automated complexes, or any other flexible automated production. The vibrating hopper loading devices are most commonly used in transportation and loading of details on working positions of assembly automatic machines and assembly automated complexes. In this case the details must be issued in a clearly oriented state. For this purpose, the stationary automated orienting devices, or the orienting devices located directly on the working vibrating feeders` bodies are used. Low compressed air pressure is often used in these devices. Apart from this, in some cases the low compressed air pressure is used in vibrating feeders to increase the maximum lifting angle when vibrating transportation of details on a transport tray of the feeder. We already know the designs of vibrating feeders, whose transport tray is equipped with channels and openings for the supply of compressed air, whose jets affect the parts that are transported in order to increase the maximum possible lifting angle or the speed of parts transportation, as well as to ensure the guaranteed gap between them at the download position. We also know the vibrating feeders` constructions equipped with jet pneumatic devices, which are set exactly on the vibrating feeder hopper and serve for non-contact orientation of details that are issued. All of these devices use the low compressed air supplied by means of the flexible pipeline from a workshop pneumatic network. But the fact that such network is simply absent in many enterprises` workshops makes it impossible to use the vibrating feeders like these, this way decreasing their use. For expanding their use it is necessary to have vibrating feeders with individual low pressure compressed air source. Modern production manufactures new models of machines with high technical economic indicators, so functionality increase of the existing one equipment and the development of new schemes of machines is an important task for designers and technological equipment manufacturers, because minimal improvement of its technological and performance can lead to a significant economic effect. The set of elements affecting the performance and efficiency of vibrating bunker feeders with electromagnetic drives that have a directional elastic system are presented in this paper. The additional structural elements increasing the functionality of such feeders are offered.

Modeling the Production Technology of Fully-Pressed Bi-Metal Powder Materials and Products

The features of calculating the thickness of the layers of bimetallic powder products without holes and the type of bushings are shown. The effect of the particle size distribution of the powders, the kinematic and geometric parameters of the loading devices and molds on the mechanism of the expiration of the powder mixture and on the thickness of the layers of the molded product is studied. A technique has been developed for determining the dimensions of the feeder cassette and tooling, depending on the overall dimensions and thicknesses of the working layers, in the production of whole-pressed bimetallic products on press machines with a vertical arrangement of layers. It was found that the thickness of each layer of bimetallic products depends on the geometric parameters of the feeder cassette and tooling, bulk density, particle size distribution and other characteristics of the powders, as well as on the speed of lowering the lower punch ν1 .

Reliability Test Rig of the Motorized Spindle and Improvements on Its Ability for High-Speed and Long-Term Tests

To realize the accurate performance test under high-speed operation and the long-term stable reliability test of the motorized spindle, a reliability test rig (RTR) which can simulate the cutting force in the actual machining process is presented. Firstly, a reasonable prototype integrating dynamic force loading devices and torque loading devices is designed and established based on the load analysis of the spindle, and a complete and explicit control strategy of the reliability loading test is designed. Secondly, the effects of misalignment of the diaphragm coupling caused by assembling are analyzed, and experiments are conducted to test the axis orbit of the motorized spindle. The experimental results illustrate that the axis orbit can identify the occurrence of misalignment, which ensures timely adjustment of misalignment and the accurate performance test under high-speed operation. Lastly, a damper is added in the mechanical structure of the electrohydraulic servo loading system (EHSLS), and the comparison of Bode maps before and after optimization is analyzed by the Nyquist criterion. After the optimization, the gain and phase margin of the Bode diagram are 12.9 dB and 57.2°, respectively, which are both within the stable range and validate the improvements on the ability of long-term reliability tests of the motorized spindle. The presented RTR is able to simulate the actual cutting force and provides an efficient loading approach to guarantee the accuracy and stability of motorized spindle tests.

Improving the performance of vibration feeders with an electromagnetic vibration drive and a combined vibration system

Vibration loading devices are widely used in various branches of mechanical engineering to load piece blanks of automatic machines and automatic lines as well as robotic systems, automated systems and flexible automated production. Vibration devices for transportation and loading of miniature, small and medium-sized products are the most widely used. Modern designs of vibratory feeders, made according to the classical dynamic scheme and having a two-mass oscillating system, do not fully use the energy of the vibratory exciter to perform useful work. In addition, due to the presence of a heavy reactive mass, they have a fairly large weight. When the vibrating feeder is operating, the energy of the vibration exciter is spent on pumping both the hopper, which performs useful work, and the reactive plate, which performs idle vibrations. Thus, part of the energy of the vibration exciter is not used for performing useful work, but is spent idly. To increase the efficiency of the device, increase its performance and reduce its weight and metal consumption, it is necessary to change the design of the vibratory feeder and some of its elements, which affect the redistribution of the oscillation amplitudes of the working (hopper) and reactive mass of the vibratory feeder. Modern production involves the creation of new models of machines with high technical and economic indicators, therefore, improving the efficiency of existing equipment and the development of new schemes of machines is an important task for designers and manufacturers of technological equipment, as the minimum improvement of its technological and operational performance can lead to a tangible economic effect. To solve this problem we developed a new design vibrating hopper feeder, in which the increase of the horizontal component of the oscillation amplitude of the working element (hopper) is not at the expense of increased power of the vibratory exciter, but due to internal redistribution of energy between the elements of the oscillating system that makes better use of the energy of the vibratory exciter to perform useful work, i.e. to increase the coefficient of useful action. In addition, the weight and metal content of the vibrating feeder structure are simultaneously reduced.