КІНЕТОСТАТИЧНЕ ДОСЛІДЖЕННЯ ШАРНІРНИХ ПРОСТОРОВИХ МЕХАНІЗМІВ ГАЛТУВАЛЬНИХ МАШИН (ЧАСТИНА 2: ДОСЛІДЖЕННЯ МЕХАНІЗМУ МАШИНИ З ДВОМА РОБОЧИМИ ЄМКОСТЯМИ, ЩО З’ЄДНАНІ ПОСТУПАЛЬНОЮ КІНЕМАТИЧНОЮ ПАРОЮ)

Goal. Kinetostatic study of a statically defined hinged spatial mechanism without excessive (passive) connection of the shredding machine with two working tanks connected by a translational kinematic pair. Method. Radial and axial components of reactions in all rotating and translational kinematic pairs of the hinged statically defined spatial mechanism of the machine for processing of details with two working capacities connected among themselves by translational kinematic pair at its work at idling were determined on the basis of kinetostatic research. The study was performed using the computer-aided design system SolidWorks-2016 computer-aided design system, which performed a 3D model of a shredding machine with two working tanks connected by a translational kinematic pair. Results. 3D modeling of a shredding machine with two working tanks connected by translational kinematic pair in the computer-aided design system SolidWorks-2016 computer-aided design system is performed, maximum values of radial and axial components of reactions in all rotating and translational kinematic pairs of machine are determined, and the influence of total two working tanks for the increase of the maximum values of reactions in the kinematic pairs of the spatial mechanism of the machine. Scientific novelty. For the first time, the relationship between the total wheelbase of two working tanks and the change in the maximum values of reactions (axial and radial) in all rotating and translational kinematic pairs of the shredding machine was established. The allowable range of variation of the total wheelbase of two working tanks is determined, which creates conditions for long-term operation of the machine. Practical significance. It is established that the change of maximum values of radial and axial components of reactions in all rotating and translational kinematic pairs of the spatial mechanism of the galvanizing machine depends on the total axial distance of two working capacities of the machine. The obtained research results can be useful in the design of shredding equipment with complex spatial movement of working tanks.

Geomechanical Modeling Based on the First Success of Micro-Frac Tests in the Nahr Umr Formation in Offshore Abu Dhabi

In the studied oil field in Offshore Abu Dhabi, the intermediate hole section has suffered from borehole instability and lost circulation in the higher inclination holes. Borehole instability occurs in the Nahr Umr formation. Lost circulation occurs in the Salabikh formation. This study aims to develop geomechanical model and to analyze mud weight (MW) for successful drilling through the two problematic formations in the studied oil field. In the Salabikh formation, spatial distribution of lost circulation pressure in hundreds of wells in the whole field was analyzed. The fracture closure pressure was also evaluated based on the extended leak-off test and fracture interpretation by image logging. In the Nahr Umr formation, Micro-Frac tests in a 6" hole were implemented to evaluate the minimum in-situ stress. This was the first direct measurement of the in-situ stress in the shale. The magnitude of SHMAX was back-analyzed based on the hole geometry using interpretation of six-arm caliper and analytical solution in the two key locations. This study clarified that severe lost circulation in the crest area was likely to occur due to reactivation of the pre-existing fractures in the Salabikh formation. The lost circulation pressure was found to be approximately 1.4 SG. The study also revealed that the in-situ stress regime in the Nahr Umr formation varied from the crest to flank areas. The crest and flank areas are reverse and nearly normal faulting stress regimes, respectively. Its transition area is strike-slip faulting stress regime. The regional difference in in-situ stress regime depends on the extent of mechanical anisotropy of the shale and the magnitude of tectonic strains. By integrating the results, with respect to the borehole stability analysis in the Nahr Umr formation, instead of a conventional lower hemisphere representation of the required MW based on failure width at borehole wall, the study analyzed the geometry of the failure area around the borehole wall under the allowable range of MW constrained by the lost circulation pressure in the Salabikh formation. As a result, the borehole failure cannot be avoided in any hole inclination in the Nahr Umr formation under the allowable range of MW to prevent severe lost circulation in the Salabikh formation. Therefore, appropriate practice to transport cavings is one of the key elements for safe drilling in higher hole inclination across the intermediate hole section in the studied oil field.

Research on the mathematical modelling of the starting torque of self-lubricating spherical plain bearings

The starting torque of self-lubricating spherical plain bearings (SSPBs) is a key parameter for evaluating the performance of bearings. Therefore, the starting torque of SSPBs should be controlled to within an allowable range. In this paper, the starting torque generation mechanism is analyzed, and the critical load for the separation of the liner from the outer spherical surface of the inner ring is determined. A mathematical model of the starting torque is established; the experimental and theoretical results of the starting torque are compared and analyzed, and then the accuracy of the mathematical model is evaluated by the deterministic coefficient R2. The research reveals that a critical load exists for the starting torque. Below the critical load, the starting torque is dependent on the outer spherical radius of the inner ring, bearing wrap angle, and liner parameters such as the compressive elastic modulus, friction coefficient, and precompression of the liner; however, the starting torque is independent of the radial load. Above the critical load, the starting torque is also dependent on the radial load. The research results provide a theoretical basis for the design and application of bearings.

Analysis of Coaxiality-Transmission Efficiency Vector Model of RV Reducer Based on ADAMS

Aiming at the influence of the coaxiality error of the transmission system on the detection accuracy of the RV reducer performance test device, taking RV-20E reducer is used as the research object, combined with the ADAMS dynamic simulation software, the RV reducer dynamic transmission coaxiality and transmission efficiency vector model is established, and the coaxiality of the transmission system of this model is simulated under different error ranges and no load. The transmission efficiency is 32.94% when coaxiality is within the allowable error range. The results verify the accuracy of the model. At the same time, when the concentricity exceeds the allowable range of error, it will have a great impact on the transmission efficiency. The design of the coaxiality adjustment mechanism of the RV reducer performance detection device has certain theoretical significance and practical value.

Experimental Verification of Analysis Model of Seismic Isolation With High-Static-Low-Dynamic Stiffness

This paper verifies the model of high-static-low-dynamic stiffness (HSLDS) for seismic isolation based on an experiment. Seismic isolation is widely used in several countries. Moreover, the number of seismically isolated buildings has rapidly increased in these few decades. Seismic isolation extends a natural period of a building and decreases the absolute acceleration to re-duce a seismic force. However, as there is a trade-off between displacement and absolute acceleration, it might result in the maximum displacement be-yond an allowable range. HSLDS is nonlinear, and its restoring force can be approximated cube of a displacement. Thus, HSLDS applies a large restoring force for significant displacement, and the force is small for small perturbation around an equilibrium position. To improve the control performance of seismic isolation for displacement, we apply HSLDS for seismic isolation. This paper conducts an experiment and compares the results with a time-history analysis to verify a numerical model of HSLDS

Agglomerate Fog Early Warning Method based on GWR Model

In order to realize the early warning of Agglomerate fog-prone sections, reduce accidents and ensure the safety of personal and property. Taking Shandong Province as an example, according to the statistics of the time and location of the roads where the agglomerate fog occurs and the number of occurrences in 2018, the time and space analysis of the agglomerate fog occurrence is carried out, and combined with the analysis of the correlation between the frequent occurrence of agglomerate fog and the elevation of Shandong Province, river density, and Normalized Difference Vegetation Index (NDVI), construction of Geographically Weighted Regression (GWR) model to study the geographical environment conditions of highways prone to foggy weather, the influence of regional altitude, river density analysis and NDVI on the occurrence of agglomerated fog. The research results show that the number of agglomerate fog occurrences in different regions has a strong spatial correlation, that is, the environment of different regions has a greater impact on the number of agglomerate fog occurrences. The agglomerate fog early warning model built with regional river density, elevation difference and NDVI as independent variables can effectively predict agglomerate fog-prone areas. The prediction result shows that more than 98% of the area is within the allowable range of error.

Truck Impact on Buried Water Pipes in Interdependent Water and Road Infrastructures

In the development of sustainable and resilient infrastructures to adapt to the rapidly changing natural and social environment, the complexity of the dependencies and interdependencies within critical infrastructure systems need to be fully understood, as they affect various components of risk and lead to cascading failures. Water and road infrastructures are highly co-located but often managed and maintained separately. One important aspect of their interdependence is the impact of vehicle loading on a road on underlying water pipes. The existing studies lack a comprehensive evaluation of this subject and do not consider possible critical failure scenarios. This study constructed finite element models to analyze the responses of buried water pipes to vehicle loads under an array of scenarios, including various loads, pipe materials, pipe dimensions, and possible extreme conditions, such as corrosion in pipes and a sinkhole under the pipe. The results showed negligible impact of heavy trucks on buried water pipes. The pipe deflection under a maximum allowable truck load in the worst condition was still within the allowable range specified in standards such as those from the American Water Works Association. This implies that the impact of heavy vehicles on water pipes may not need to be considered in the context of the interdependency between water and road infrastructures, which leads to a more unidirectional dependency between these two infrastructures.

Design of Optimal Controllers for Unknown Dynamic Systems through the Nelder–Mead Simplex Method

This paper presents an efficient method for designing optimal controllers. First, we established a performance index according to the system characteristics. In order to ensure that this performance index is applicable even when the state/output of the system is not within the allowable range, we added a penalty function. When we use a certain controller, if the state/output of the system remains within the allowable range within the preset time interval, the penalty function value is zero. Conversely, if the system state/output is not within the allowable range before the preset termination time, the experiment/simulation is terminated immediately, and the penalty function value is proportional to the time difference between the preset termination time and the time at which the experiment was terminated. Then, we used the Nelder–Mead simplex method to search for the optimal controller parameters. The proposed method has the following advantages: (1) the dynamic equation of the system need not be known; (2) the method can be used regardless of the stability of the open-loop system; (3) this method can be used in nonlinear systems; (4) this method can be used in systems with measurement noise; and (5) the method can improve design efficiency.

Substantiation of technological parameters in the production of composite polyphenylene sulfide-based tape

The purpose of the study was to select technological parameters of the production line of unidirectional thermoplastic polyphenylene sulfide-based tapes. The selection was made relying on the variation of the tape speed, the temperature of the sub-melting furnace, and the calendering module in the simulation of heat transfer processes. Modeling of heat transfer was based on the results of tests to determine the temperatures of phase transitions of a thermoplastic polymer in the composition of composite material and the dependence of the heat capacity of the composite on temperature. The indicated properties of the material were determined by analyzing the dependences obtained during differential scanning calorimetry and thermogravimetric analysis. As a result, the allowable range of distances between the polymer binder melting furnace and the calendering module was determined, which provides the necessary tape temperatures at the stages under consideration and the manufacturability of production. The permissible range of distances between the calendering module and the coiling module was also determined.

Analyzing the Solution of Chemotaxis Equations with Logistic Source Term

When the parameters have the characteristics of sensitivity and specificity, while the traditional analysis method is the analysis of equations, under the influence of the characteristics of parameters, because the ability to consider the overall existence and limitations of the equation is weak, this leads to the deviation of the analysis results beyond the allowable range. With the chemotactic equations with logistic source terms, a new analysis method is proposed, on the basis of setting the optimal adjustment parameters of logistic source term, the method evaluates the well-posed behavior of the solution of the chemotactic equation system with logistic source term by quantitative analysis of the global existence and limitations of the solution. The experimental results show that the proposed analysis method, after the analysis of the overall existence and limitations of the equation, has smaller deviation in the results of the appropriate qualitative evaluation and meets the analysis requirements of the solution problem of the chemotaxis equations. It can be seen that the analysis method is more practical.