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1

Experimental and numerical investigation of scour downstream contracted spillways

Nasralla Tarek H.

Journal of Water and Land Development

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2022

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no. 52

53--59

EN

A study of scour downstream of free hydraulic jump in stilling basin of stepped spillways was carried out. This paper employed an experimental study to investigate the stepped spillway with the movable bed material of D50= 3.1 mm. The effect of the contraction ratio of the stepped spillway was highlighted. Different downstream divergent angle was studied to minimise the scour depth, the results showed that the relative scour depth was reduced by 23% for divergent angle is equal to 170°, different shapes of buffer in stilling basin were also studied to reduce the scour depth where the considered buffer decrease the relative scour depth up to 84%. This study was simulated by Flow 3D program to analyse the scour hole formed using velocity vectors at the bed. The simulated results well agreed with the measured data.

2

Wzmacniacz pomiarowy o podwyższonych parametrach metrologicznych do zastosowań w paśmie akustycznym

Furmankiewicz L.

Pomiary Automatyka Kontrola

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2014

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R. 60, nr 11

954--956

PL

W artykule przedstawiono strukturę rozbudowanego, dwukanałowego wzmacniacza pomiarowego (bufora) o podwyższonych parametrach metrologicznych w paśmie częstotliwości akustycznych. Wzmacniacz jest elementem systemu pomiarowego, w którym pełni rolę stopnia dopasowującego napięcia pływające do niesymetrycznego wejścia układu pomiarowego. Przedstawiono wyniki badań eksperymentalnych wybranych stopni wzmacniacza.

EN

The paper presents an extended structure of two-channel instrumentation amplifier (IA). The IA has higher metrological parameters relating to typical-setup of an instrumentation amplifier (Fig. 2) in the audio frequency range. The IA is intended for use in a measurement system to calibrate low-value alternating-current standard resistors at audio frequencies. In the developed system a resistor RX is directly compared with a standard resistor RN (Fig. 1). The impedance ratio ZX/ZN of the resistors is determined from the measurement of the voltage ratio UX/UN. The measurement of floating voltages by a digitizer with grounded inputs requires IA (buffers) (B1, B2). Due to the assumptions concerning the system being developed, buffers should be characterized by a relatively high input impedance and small errors of the transformer voltage ratio over a frequency bandwidth from 40 Hz to 10 kHz. Block diagram of the IA is shown in Fig 3. The IA consist: two input buffers (BW1, BW2), input stage (SW) with floating ground (PM), difference amplifier (SR) and circuit for common mode voltage adjustment (KWNW). Figs. 4, 5, 6, 7 show a simplified schematic diagrams of the individual IA stages. In Figs. 8 and 9 the frequency characteristics of the module and phase error of the input buffer (BW1) voltage ratio are shown. The frequency characteristics of the input buffer BW2 are almost the same. In Fig. 10 the frequency characteristics of CMRR prior to adjustment and following the adjustment the real part of the CMR are shown.

3

A comparison of buffer sizing techniques in the critical chain method. case study

Ślusarczyk A., Kuchta D., Verhulst P., Huyghe W., Lauryssen K., Debal T.

Journal of Automation Mobile Robotics and Intelligent Systems

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2013

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Vol. 7, No. 3

43--56

EN

The presented paper is an attempt to evaluate the application of different buffer sizing methods (within the critical chain approach) to a real-life project, in order to show that it is important to choose consciously one of the existing methods. The implementation of the different approaches to the buffer sizing procedure resulted in eight unique schedules. Once all the methods were implemented, the authors of this paper stumbled upon 2 inconveniences (slack vs. buffer, splitting up buffers). Funding solution for these handicaps caused obtaining eight more schedules. In order to evaluate all the determined solutions, the authors decided to establish a simulation study. A random dataset was generated of 2000 observations using the mean and variance calculated for the probability distribution determined by three possible durations (optimistic, expected and pessimistic) given by the project team members. To validate the performance of different methods, two penalty systems were designed. The test results indicate which specific buffer sizing technique performs best in the presented case, taking into account the attitude of the decision maker. The simulation study is the proposal of a method to be applied in each case of the critical chain method application, because it makes the use of the critical chain method more effective.

4

Subassembly flow control with the Kanban system as a component of Lean Manufacturing at a production enterprise

Michlowicz E.

Total Logistic Management

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2009

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no. 2

51-65

EN

The paper analyses the Kanban system introduced at a company manufacturing multiple types of rotors for electricity-powered engines. The system comprises two loops of Kanban cards: the production card loop and transport card loop. The main assumptions for the system is the capacity minimisation for buffers between operations and streamlining the information flow between individual production cells. The analyses use the 7M, 5S and SMED methods, as well as a combination of the ABC and XYZ classification methods for materials. The introduction of the Kanban system significantly reduced warehouse stocks and improved communication between individual production lines.

PL

W opracowaniu przedstawiono analizę systemu Kanban, który został wprowadzony w firmie produkującej wiele odmian wirników silników elektrycznych. System składa się z dwóch obiegów kart Kanban: pętli kart produkcyjnych oraz pętli kart transportowych. Głównym założeniem systemu było zminimalizowanie pojemności buforów międzyoperacyjnych oraz usprawnienie przepływu informacji między poszczególnymi komórkami produkcyjnymi. W analizach wykorzystano metody 7M, 5S, SMED oraz kombinację metod klasyfikacji materiałów ABC i XYZ. Dzięki wprowadzeniu systemu Kanban znacząco zredukowano zapasy magazynowe, a także usprawniono komunikację między poszczególnymi liniami produkcyjnymi.

5

On investigation of "KAMAXIL" silicon elastomer rheological properties

Kopecki H., Majcherczyk H.

Applied Mechanics and Engineering

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1999

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Vol. 4, no spec.

51-56

EN

The methods of determination of silicone elastomer KAMAXIL rheological properties and suggestions on it application in checking of quality is presented in the paper.