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An important feature of the drums of mine shearers, is the material loading capacity onto the armored face conveyor. This characteristic is influenced by both the shape of the vane and the pitch of the helical vane. Thus, the pitch of the helical vane can be either constant or variable. This variable pitch can also have two variants. The first one is with an axial pitch when there is a progressive increase in the pitch of the helical vane towards the conveyor direction, thus resulting in a productivity increase of 15-20% compared to drums with a constant pitch. This constructive variant does not ensure the placement of the cutting picks to achieve a balanced working regime. The second constructive variant is with a radial pitch when the helical vane profile has a variable height along the generating curve. This constructive variant is considered more advantageous, ensuring a more rational placement of the cutting pitch by maintaining a constant axial pitch. In this paper a modeling is proposed for the drum of the CA-1 longwall shearer with variable axial-radial pitch. [ABSTRACT FROM AUTHOR]

The automation of the multi-rope hoisting devices requires, in a first stage, the working out of the automatic control system of the main work parameters, and then, on the basis of their interpretation, the working out of the reaction loop: computer - hoisting installation. The singular and the global interpreter of the dimensions corresponding to the main work parameters at the local of the computer through a suitable soft, the comparing of the admissible maximum or minimum values, allows the command of the hoisting installation through the computer. The paper contributes to the minimizing of the human factor intervention in the work of the hoisting installation leading to the increasing the safety in exploitation and the command through a numerical computer leads to the decreasing of the dynamic stresses at the mechanical parts are subjected during the exploitation, what means a growth of the transport capacity. [ABSTRACT FROM AUTHOR]

The processes and technologies for supporting the roof of underground mining works have advanced during the years, thus fundamental changes resulted in both the roof control and the exploitation from economic and technical points of view. The support of the underground excavation roof is carried out by two methods, namely using individual supports, usually metal beams and props, or hydraulic powered supports/shields, the latter representing the most up-to-date technology. The paper presents a virtual model of a powered roof support section made in SOLIDWORKS. For its components a mechanical analysis was performed through the static simulation of the pressure of the roof on the support beam. [ABSTRACT FROM AUTHOR]

The health crisis we have experienced has sharply raised the issue of monitoring indoor air pollution, especially in rooms where people are carrying respiratory viruses. Within this context, this paper aims to present a case study where air patterns are numerically simulated in a two-bed hospital reserve, by using or not a portable air conditioner, by developing a computational fluid dynamics model. The key purpose of the work is to identify the manner the air pattern found in absence of the portable air conditioner gets modified in its presence. Actually, the particular idea is to find the most appropriate bed to host a patient who fortuitously got a flu when staying in the hospital with minimal threat on the health state of the other patient - supposing that the reserve serves for other purposes than treating for transmissible breathing diseases. [ABSTRACT FROM AUTHOR]

In the automotive industry, acoustical materials play an essential role in the reduction of rolling noise levels. Such insulators are bonded to exposed cavities by means of adhesives. The gluing process benefits from the wide scale use of pneumatic actuators. One essential aspect of the underlying air drives is the dynamic control of the actuating force. The present paper proposes a new approach for deriving the transfer function of the plant by employing transient structural simulations. A numerical computing environment is further use to decide and tune a closed-loop controller. [ABSTRACT FROM AUTHOR]

The pedestrian throw distance in the event of a frontal collision with a motor vehicle is of utmost importance, as vehicle speed at the moment of impact can be determined. This is a kind of analysis that is many times required and performed within the technical, judicial or extra-judicial technical expertise, in the case of road accidents involving pedestrians. The result of these expertise is particularly important both from the point of view of the criminal investigation, thus being able to establish guilt from legal point of view, as well as from the point of view of civil legal claims, as victims may seek compensation if the driver of the vehicle has violated the speed restrictions set for the road sector in which the accident occurred. In the paper a comparison is made between the results obtained based on equations used in specific literature and the results of the simulations performed in the specialized software called Virtual Crash. [ABSTRACT FROM AUTHOR]

Plastics are one of the 21st Century materials with an innovative development to meet the society's targets: resource efficiency, zero-energy buildings, saving water, reducing the gas emissions, waste as a resource, recycling closing the loop of “Circular Economy", to name only few. Injection molding of polymeric composites products is one of the most used processes with low cost, good accuracy and high productivity. Mold surfaces are influencing the product quality, the ejection, the flow, and the aesthetic of the part. In this paper we analyze the micro profiling of the non-planar surfaces of an injection mold for a scaled model of a 15th Century stone church from Hațeg County, Romania. We present a study of milling the micro-profiles (details of bricks and stone in the range of 100 to 500 μm) directly into the mold cavities and milling the electrodes followed by electrical discharge machining. For the milling process two strategies were compared: milling the 3-dimension model and milling/engraving the vector pattern projected on the non-planar surfaces. The experiments consisted in building an aluminum mold and evidenced a good replication by injection molding the model parts in a composite of recycled polystyrene matrix, results being compared with the flow simulation. [ABSTRACT FROM AUTHOR]

Computer Aided Engineering tools are widespread in the aerospace industry, being used in all the life cycle stages of an aircraft in order to numerically capture the behavior of parts and sub-assemblies subject to ground and flight loads. In the case of turbofan engines, apart from the design stage, simulation tools are found in a close relationship with physical geometry measurement test procedures, being used to support manufacturing changes from the baseline virtual prototypes. While such approaches are found at the maturity stage, being used in various configurations by teams geographically delimited around the world, the high degree of manual work involved together with the high level of repetitive task required lead to high amounts of time being spent on such projects with a low degree of knowledge based engineering being captured and re-used. The present paper addresses such issues by extending conventional simulation approaches with surface morphing capabilities that are embedded within computer aided engineering pre-processing software, as tools that can fill the gap between physical geometry measurements data and numerical simulation models. The given concepts are proved by means of a conceptual case study regarding manufacturing nonconformities occurring for a variable stator vane turbofan engine component. [ABSTRACT FROM AUTHOR]

The paper deals with the effect of the critical flow, which is reached during pumping of the differential pumping chamber of the Environmental Scanning Electron Microscope (ESEM). The study compares the state of the flow in the area of pumped chamber at pressure ratio on the apertures when the critical flow occurs and its advantages in design of the chambers versus the flow without the clogging the nozzle. The problem was solved using the finite volume method by the Ansys Fluent system. [ABSTRACT FROM AUTHOR]

The paper presents virtual instruments we achieved in order to simulate the behavior of balanced and unbalanced why and delta connected loads supplied with a symmetrical three phase AC voltage system. The VI-s can be used during educational classes to turn things more clear and allowing the students to experiment themselves with virtual means instead of real devices. These virtual instruments continue our work in providing educational software to help students. [ABSTRACT FROM AUTHOR]

In this paper we propose the algorithms that can be used to determine the values for several parameters that characterize the dynamic regime of operation of a DC motor. These parameters values are determined by simulation based on a state-space model by means of a virtual instrument made in LabView. In this way is possible to observe the dynamic characteristics of the DC motor in different operating conditions. [ABSTRACT FROM AUTHOR]

In this paper is presented the procedure of using Matlab-Simulink's SFunction blocks for simulating the Luenberger observer, which has the role of estimating the rotor flux of an induction machine with squirrel-cage rotor. In order to analyze the dynamic performance of the Luenberger estimator, both the effects of electric parameters variations and the effects of noise measurements are highlighted. [ABSTRACT FROM AUTHOR]

The paper deals with a LabView simulation we made for studying the operation of a d.c. generator with separate excitation. This virtual instrument is meant to allow studying the behavior of such generators when the working conditions change. The virtual instrument we achieved shows the external characteristic for different values of resistances, excitation voltage and driving speed [ABSTRACT FROM AUTHOR]

In this paper is presented the procedure of using Matlab-Simulink's S-Function blocks for simulating the mathematical mode of the induction motors with the squirrel-cage rotor, in which the iron losses are not negligible. [ABSTRACT FROM AUTHOR]

The objective of this paper is to design a Pico-hydro power plant controller based on his mathematical model. First, the natural hydro process is considered consisting of water lake, supply pipe, hydro turbine, DC generator and controller. Second, for each part of the Pico-hydro is written the mathematical model and after that the entire system is simulated in open loop. Then the controller is designed and the system is simulated in closed loop. These two control modes are compared and presented the advantages of each of them. The simulation results are as expected and can be used to design and validate the controller. [ABSTRACT FROM AUTHOR]

The paper presents a study of electrodynamics forces using MATLAB-SIMULINK software. The single-phase short circuit, and the three-phase short circuit are presented and for these situation the graphical correlation between these forces and time are presented, using MATLAB-SIMULINK software for transitory phenomena. Simulation models and theoretical basement are presented also. [ABSTRACT FROM AUTHOR]

In this paper we present a new cinematic structure of an electric vehicle driven by three induction motors with short-circuited rotors. Motion control is done by the means of three DFOC type position vector regulating systems that contain Gopinath type rotor flux estimators in their loops. [ABSTRACT FROM AUTHOR]

This paper shows how simulation modeling and control of a support section with Petri Nets using Visual Object Net + +. During development of this software, special attention was given to use intuitive, thanks to ease of design, simulation fast and clear documentation of Petri networks. In the current version, events / terms of Petri networks planned with infinite capacity are allowed. [ABSTRACT FROM AUTHOR]

In this paper the main renewable energy resources in order to design of an integrated renewable energetic system are first presented. Second, is presented the integrated energetic system concept. The integrated system has following characteristics: microclimate; envinroment integrated; sustainable; renewable; clean energy; software oriented; systemic structure. This principle is used for designing a proposed energetic system to produce renewable energy based on sun, water, wind and biomass in an environmental local microclimate context. [ABSTRACT FROM AUTHOR]

The extraction and processing of minerals from surface mines and quarries can produce significant fugitive emissions as a result of site activities such as blasting, unpaved road haulage, loading, primary crushing and stockpiling. Uncontrolled fugitive dust emissions can present serious environmental, health, safety and operational issues impacting both site personnel and the wider community. This paper proposes that optimal modeling of open pit emissions may be more accurately achieved by the use of a multi-scale predictive modeling approach utilizing computational fluid dynamics methods for high resolution near source dispersion and conventional Gaussian based methods for far field dispersion modeling. Typical operating emissions and meteorological conditions are obtained from long term data records collected at a large operating quarry extraction operation. Emissions can be modeled using a specific framework within conventional atmospheric boundary layer profiles expressed as functions of turbulence and velocity parameters under assumed neutral conditions. [ABSTRACT FROM AUTHOR]