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THE FIRST BULGARIAN INDUSTRIAL ROBOT “PROBO” 1987

Abstract

The paper presents the first Bulgarian industrial robot “PROBO” build up entirely on elements, tools and human efforts at the former “Precision mechanics” laboratory within the Bulgarian Academy of Sciences. The robot was publicly demonstrated at Plovdiv exposition in 1987. The place of the robot in the world timeline is shown. A definition of “robot” is proposed, as well.

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Online Forecasting of the Solar Energy Production

Abstract

Forecasting the solar energy production is a key issue in the large-scale integration of the photovoltaic plants into the existing electricity grid. This paper reports on the research progress in forecasting the solar energy production at the West University of Timisoara, Romania. Firstly, the experimental facilities commissioned on the Solar Platform for testing the forecasting models are briefly described. Secondly, a new tool for the online forecasting of the solar energy production is introduced. Preliminary tests show that the implemented procedure is a successful trade-off between simplicity and accuracy.

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LIDAR Measurements Comparison Of Two Volcanic Eruptions: Environmental Influences Upon The Romanian Territory

Abstract

The eruption of both the Eyjafjallajokull (April 2010) and Grimsvotn (May 2011) volcanoes cumulated with two moments that gave headaches to the authorities and air traffic, and their impact on the environment upon Iasi region have been studied by means of different tools evidencing the complexity of the phenomena. In order to evidence the intrusion of pollutants in the cloud systems and to obtain additional data on the intrusion when the ash cloud was over our country, LIDAR measurements, meteorological (NMA), Satellite data (EUMETSAT), and various forecasting models (ECMWF, VAAC-Met Office, HYSPLIT) have been used. The new 3D Atmospheric Observatory Site of the Alexandru Ioan Cuza University of Iasi, as part of RADO (Romanian Atmospheric 3D Observatory) is presented, too.

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A MEASURING SYSTEM WITH AN ADDITIONAL CHANNEL FOR ELIMINATING THE DYNAMIC ERROR

Abstract

The present article views a measuring system for determining the parameters of vessels. The system has high measurement accuracy when operating in both static and dynamic mode. It is designed on a gyro-free principle for plotting a vertical. High accuracy of measurement is achieved by using a simplified design of the mechanical module as well by minimizing the instrumental error. A new solution for improving the measurement accuracy in dynamic mode is offered. The approach presented is based on a method where the dynamic error is eliminated in real time, unlike the existing measurement methods and tools where stabilization of the vertical in the inertial space is used. The results obtained from the theoretical experiments, which have been performed on the basis of the developed mathematical model, demonstrate the effectiveness of the suggested measurement approach.

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Vibration Effects Examination of Cushions Used on Tractor Driving Seat

Abstract

Vibration effect of driver’s seat of agricultural tractor which works in land condition has been researched. In this research, three dif- ferent cushions on driver’s seat have been used. These are wool, sponge and cotton. Pad acceleration receiver is put on seat. Moreover, HVM100 tool has been used to record data. Data has been converted to graphs in BLAZE software. Statistical methods have been used in examining the graphs. In vibration isolation, ordering has been achieved as wool, cotton and sponge and without a cushion, respectively. Wool cushion has the best isolation. It is seen that data obtained from test results is appropri- ate according to ISO 2631 standards and scientific researches.

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The Aharonov-Bohm Effect and Transport Properties in Graphene Nanostructures

Abstract

This paper investigates the possibility to improve the filtering process of flue gas by separation of suspended nanoparticle using dielectrophoresis. The study focuses on the particles having an average radius of about 50-150 nm, that cannot be filtrated by classical techniques but have a harmful effect for environment and human health. The size distribution nanoparticles collected from the flue gas filters of a hazardous waste incinerator plant were evaluated. Based on obtained experimental data and a proposed mathematical model, the concentration distribution of nanoparticle suspended in flue gas inside a microfluidic separation device was analyzed by numerical simulations, using the finite element method. The performances of the device were described in terms of three new specific quantities related to the separation process, namely Recovery, Purity and Separation Efficiency. The simulations could provide the optimal values of control parameters for separation process, and aim to be a useful tool in designing microfluidic devices for separating nanoparticle from combustion gases.

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Wave Propagation Due to an Embedded Seismic Source in a Graded Half-Plane With Relief Peculiarities. Part II: Parametric Study

Abstract

The mechanical model and the accompanied computational technique, based on the boundary integral equation method (BIEM) and Green’s function for continuously inhomogeneous half-plane were described in the first part of this work. 2D elastodynamic problem for quadratically inhomogeneous and heterogeneous geological area was defined in the first part of our work. The aim of the current second part is to demon-trate the accuracy and the convergence of the proposed computational tool. Furthermore, subsequent extensive parametric study will illustrate, that the seismic wave field is a complex result of mutual play of different key factors as free-surface relief, wave characteristics, as frequency and wavelength, seismic source properties, type and characteristics of the material gradient, existence of different type of heterogeneities and their interactions.

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Experimental Research of Rotational-and-Frictional Boring of Big Holes in Large Parts

Abstract

When producing large-dimensional parts of heavy machines, the largest specific weight in the general labour input is made by the operations, connected with machining the main holes, i. e. holes of large diameter. To the holes of large diameter of large-dimensional parts, there are specified high requirements in the aspect of accuracy of the size, shape and arrangement. Machining of holes still remains one of the topical problems of present day mechanical engineering, in particular machine-building enterprises of the Republic of Kazakhstan.

Solving the problem of ensuring accuracy and quality of machining large holes of large-dimensional parts requires the development of new resource-saving technologies of machining. In this work there are presented the results of studying a resource-saving method of rotation-friction boring of large diameter holes. There has been achieved good results in providing the quality indicators, when machining by the proposed method of rotation-friction boring with the use of the tool (a disk cutter) made of steel 90CrSi5 in comparison with well-known boring of holes. The diagram of chip formation of cutting and the results of studying the zone of chip formation by the metallographic method is also presented.

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Wave Propagation Due to an Embedded Seismic Source in a Graded Half-Plane with Relief Peculiarities Part I: Mechanical Model and Computational Technique

Abstract

This work addresses the evaluation of the seismic wave field in a graded half-plane with free-surface and/or sub-surface relief subjected to shear horizontally (SH)-polarized wave, radiating from an embedded seismic source. The considered boundary value problem is transformed into a system of boundary integral equations (BIEs) along the boundaries of the free-surface and of any sub-surface relief, using an analytically derived frequency-dependent Green’s function for a quadratically inhomogeneous in depth half-plane. The numerical solution yields synthetic seismic signals at any point of the half-plane in both frequency and time domain following application of Fast Fourier Transform (FFT). Finally, in the companion paper, the verification and numerical simulation studies demonstrate the accuracy and efficiency of the present computational approach. The proposed BIE tool possesses the potential to reveal the sensitivity of the seismic signal to the type and properties of the seismic source, to the existence and type of the material gradient and to the lateral inhomogeneity, due to the free-surface and/or sub-surface relief peculiarities.

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Seismic Soil-Tunnels Interaction Via Bem Part I. Mechanical Model

Abstract

Two-dimensional elastodynamic problem for seismic response of unlined and lined tunnels located in a layered half-plane with free surface relief is solved. The computation tool uses the idea of the global matrix propagator method which allows derivation of a relation between the wave field quantities along different interfaces in the layered half- plane. The numerical realization of this idea is performed with the help of the sub-structured boundary element method (BEM) well suited when objects with arbitrary geometry are considered. A relation between dis- placements and tractions along the free surface and arbitrary interface of the soil stratum is derived. It works for arbitrary geometry of the interfaces between soil layers. Finally, in the companion paper, numerical results are presented which show both a validation study of the pro- posed computational methodology and extensive numerical simulations demonstrating the influence of some important factors as type and characteristics of the incident wave, dynamic tunnels interaction, soil-tunnel interaction, free surface relief, type of the tunnel construction and mechanical properties of the layered half-plane on the complex seismic field near and far-away from the underground structures.

Open access