Development of a simulation dump truck dynamics model to estimate loads acting on its carrier and load platform when loading and dumping bulk loads

It is important for mining dump trucks to minimize the weight of the carrier and the load platform while maintaining a sufficient level of their rigidness and strength. This requirement significantly affects the weight of the transported material, the cost of transportation and, consequently, the economic efficiency of mining operations. Processes of loading and dumping of bulk loads, which is transported by dump trucks, make a significant contribution to reducing the service life of the carrier. Therefore, proper consideration of the bulk load dynamics is an important and relevant task. Contemporary systems for calculating the dynamics of solids allow for joint modeling with applications designed to calculate the dispersed body dynamics. This approach helps to obtain adequate loads in the pivots and force links of the model, to analyze the loading of the load platform, to asses the durability of the dump truck elements, to define the geometry of the load platform. In order to perform the simulation, it is required to develop a mathematical model of a dump truck, including all its key elements and subsystems, a model of the bulk load, and a model of the load platform. The purpose of the study is to develop a mathematical model of a mine dump truck to determine the loads in the pivots and force links connected to the carrier and the load platform for the strength calculations and durability analysis. The calculations are made with the combined use of the solids dynamics calculation system and the application to calculate the dynamics of dispersed bodies.

Nitrogen as an environmentally friendly suppression agent for aircraft cargo fire safety

Fire suppression systems in cargo compartments are a certification requirement for commercial aircraft safety. Halon production was banned and usage ends in 2040 according to Montreal Protocol for environmental reasons. This necessitates an alternative environmentally friendly agent. Quantitative analysis of nitrogen as agent established suitability of the suppression system. The Minimum Performance Standards specifies the qualification procedure of an agent through four scenarios – bulk load; containerised load; surface burning; and aerosol can explosion. Empirical sources from Airbus, independent computational fluid dynamics studies and small-scale cup-burner tests indicate suitability of nitrogen specific to aircraft cargo fire suppression. The nitrogen delivery system and the experimental apparatus are presented. Extensive commissioning tests verified instrumentation reliability. All the four scenarios were conducted at Cranfield University, in a replica of a wide-body aircraft cargo compartment. In a reduced oxygen environment (11%) obtained with nitrogen discharge, the aerosol can explosion tests were performed without any evidence of explosion or pressure increase beyond the expected baseline value. The surface burning scenario was completed successfully and passed the Minimum Performance Standard criteria. The maximum average temperature was found to be 220°C (limit – 293°C). All the scenarios passed the Minimum Performance Standard criteria for indicating successful prevention of Class B fire re-ignition. Similarly, the containerised and bulk-load scenarios obtained results that passed the Minimum Performance Standard criteria for successfully maintaining continued fire suppression for a specified period of time. The maximum average temperature in containerised-load fire scenario was found to be 210°C (limit – 343°C) and in bulk-load scenario was 255°C (limit – 377°C). Additional qualification criteria and system design are presented in this article according to the Minimum Performance Standard format. This work can be extended to introduce standard testing for safety critical systems, such as engine bay and lithium-ion fires.

Measurement and Analysis of the Dynamic Load Modeling for Smart Grid Environment

This paper mainly focuses the dynamic modeling to overcome the severe challenges of dynamic characteristics of loads of Smart Grid System in Kuching and Samalaju, where facility loads have significant consequences to the power system stability. Appearances of conventional types of loads, which are power-electronic, based or interfaced and it requires operating with increasing non-conventional and intermittent types of generation. These lead to an interest in dynamic modeling. In Sarawak Energy Berhad (SEB) power grid, the instability of the voltage, frequency deviations of the power system can damage the bulk load and important data as well. Dynamic modeling is a technique used to model the system to study the power system stability, including system voltage, frequency, and oscillation of the generation. This paper proposes dynamic modeling that will be done based on the data at the Kuching Bulk Load of SEB. Moreover, this study also assesses the time-domain dynamic simulation by comparing the recorded and simulated response as well as assess the parametric study using the parameter estimation method (Least Square Error). The selected model of the bulk load can be optimized by converging on the data of the Least Square Error Method in this study.

Determination of the limiting angle of inclination of tubular belt conveyor

Currently, the widespread use of tubular belt conveyors is constrained by insufficient justification of the conveyor parameters. In the work, on the basis of the theory of the limiting equilibrium state of bulk load, equations of equilibrium of load on the belt of an inclined tubular conveyor are obtained. It is assumed that the belt was a rigid cylinder filled with bulk material in extreme equilibrium. Based on the obtained equilibrium equation, the analytical dependences of the limiting angle of inclination of the belt conveyor with a tubular belt on the degree of unfilling with the bulk load of the belt and the properties of the bulk load are found. From the analysis of these dependencies it follows that the limiting angle of inclination of the tubular belt conveyor depends on the angle of internal friction of the transported load, the angle of friction of the load on the conveyor belt, the angle of unfilling of the belt with load and does not depend on the radius of the conveyor belt.

Performance analysis of write operations in identity and UUID ordered tables

Design of the database includes the decision about the physical storage. This is often overlooked as 1) this cannot be expressed in standard SQL and in result each Database Systems have their own way to specify the physical storage and 2) the decision is often made implicitly. This is dangerous situation as many of the databases use B+ trees as table implementation which stores the data physically sorted by some ordering attribute. The choice of the ordering attribute largely affects read and write operations. Commonly, IDENTITY/AUTO_INCREMENT constraint are being chosen as ordering attributes, due to their easy usage and monotonic nature. In some cases ordering tables by the attributes whose values are drawn from uniform distribution leads to better performance in terms of Transactions-Per-Second. Such cases includes situation when data does fit entirely in-memory or when we can limit the set of physical pages being accessed. In the end, however, We cannot entirely say that either monotonic or random attributes are superior. Both have their pros and cons. In this article We present (1) short description of the data structures in contemporary Database Systems, (2) the advantages and the disadvantages of the two common types which are used as the clustering attributes: GUID and IDENTITY, (3) performance analysis of write operation which compare both data types using B+ tree as primary storage and (4) evaluate the efficiency of these bulk load operation using heap files and B+ trees.

Limit angle of the belt conveyor inclination at transporting lumpy loads

One of the ways to reduce capital costs and shorten length of conveyor transport routes is to increase angle of the conveyor inclination. As practice shows, limit inclination angle of general-purpose belt conveyors transporting bulk loads is 18°- 22°, while angle of natural slope of ore and coal is 40° and 35°, respectively. Such a difference between the angles of bulk load slope and limit inclination angle of the belt conveyor transporting the bulk loads is explained by the belt vibration impacting on the state of the transported load during its moving along the belt conveyor idlers. When exposed to vibrations, the solid-yielding state of the granular medium passes into a free-dispersed state at which inertial forces of the particles exceed the forces of internal coulomb friction between the particles. Moreover, as experimental studies have shown, granular medium moves relative to the conveyor belt at anglesof conveyor inclination of 18°–22°, i.e. limit angle of inclination of the conveyor belt transporting bulk load does not exceed 18°–22°. Today, limit angle of inclination of the conveyor belt transporting bulk loads is not studied well. In this research, the authors tried to determine limit angle of inclination of the conveyor belt transporting bulk loads by considering different types of the idlers: with rigid line, damping idlers and suspension idler with rope line. Limit angle of the conveyor belt inclination was determined on the basis of the change in momentum theorem applied to the lump during its moving over the idler and with the assumption that a lump, while passing over the idler, began sliding along the conveyor belt. As a result, analytical dependences of limit angle of the conveyor belt inclination on the conveyor parameters (belt tension and speed), parameters of idlers (distance between them), length of the bulk load and coefficient of friction of the lump against the conveyor belt were obtained. The studies of the obtained dependences showed that belt conveyors with damping idlers featured the widest limit angle of inclination, and inclination angel of the belt conveyors with suspension idlers had the least value. In addition, it was found that with increase of the conveyor belt speed and weight of the transported lumps limit angle of the conveyor inclination decreased and increased with increase of the belt tension. Further, critical speed of the conveyor belt was determined at which piece of load began sliding along the conveyor belt at any angle of the conveyor inclination.

Mathematical model of the stress-strain state of belt with the load of tubular belt conveyer

The article developed a mathematical model of the stress-strain state of a tubular conveyor belt filled with bulk load. In this case, the belt is considered as a thin elastic inextensible cylindrical shell, and the bulk load in the belt is in the limit state. A system of differential equilibrium equations for a tubular belt with a bulk load with respect to forces and bending moments in a belt was obtained, which, when simplified, was reduced to a fourth-order differential equation for belt deflections. Based on this mathematical model, analytical dependencies of the deflections of the tubular conveyor belt on the parameters of the conveyor, the radius and properties of the belt, as well as the properties of the bulk load are obtained and analyzed. As a result, the maximum allowable distance between the roller supports of the tubular conveyor is determined. It was found that the allowable distance between the roller bearings is directly proportional to the tension of the belt and inversely proportional to the square of the radius of the belt and the bulk weight of the load. The research results can be used in the design of tubular belt conveyors transporting bulk load.

Design and fabrication of Windchill for low cost vegetable preservation

In Bangladesh, every year a huge amount of vegetables are being lost after harvesting from the field due to inadequate storage facilities at farmers’ level. Considering this a low cost storage chamber, windchill was designed and fabricated that consumes low power to operate by a 12V duct fan. The average temperature inside the chamber at no load condition was found 24.7◦C with a relative humidity of 77.2% while the outside temperature and relative humidity were 28.9◦C and 54%, respectively. Performance of the chamber was tested keeping vegetables inside the chamber for four and five days during pre-test and bulk load test, respectively. During bulk load test the temperature and relative humidity inside the chamber were 24.7◦C and 77.1%, respectively while outside the chamber, these were 28.8◦C and 52.8%, respectively. After four days weight loss percentage inside the chamber at pre-test condition were 1.76% (tomato), 3.53% (brinjal), 5.2% (greenchili) and 18.16% (red amaranth) while weight loss outside the chamber were 4.18% (tomato), 9.52% (brinjal), 14.44% (greenchili) and 49.44% (red amaranth). Weight loss percentage at bulk load condition inside the chamber was 1.46% while outside the chamber was 15.15% at 5th day. Physical appearance of vegetables kept inside the chamber was also much better than those kept outside the chamber. The panel test result for evaluating physical appearance was found satisfactory based on their acceptance level after preservation. The initial construction cost of the full unit was Tk. 6010 which was found cost effective for farmers to store their vegetables for several days after harvesting. Progressive Agriculture 30 (2): 209-218, 2019