Automatic water level control system using discretized components

This study is based on the design of a portable automatic water level control switch that is capable of switching on the pump when the water level in the overhead tank goes low and switches it off as soon as the water level reaches a pre-determined level to prevent dry-run of the pump in case the level in the underground tank goes below the suction level. The water in the tank is measured by the conductive probes and displaced via the LED indicators. At maximum-set capacity the pump is de-energized to automatically switch off, thereby stopping the inflow of water into the tank. The design approach involves three major stages which are: the power supply unit, the sensing unit, and the motoring and relay unit. The uniqueness of this work is the use of discrete components such as transistors to achieve water level control. This approach is more economical, simpler and easier to implement than the sophisticated programmable logic controllers and computerized microprocessors. Keywords: discrete components; conductive probes; sensors; relays; pum

Automatic Water Level Control System Using Discretized Components

This study is based on the design of a portable automatic water level control switch that is capable of switching on the pump when the water level in the overhead tank goes low and switches it off as soon as the water level reaches a pre-determined level to prevent dry-run of the pump in case the level in the underground tank goes below the suction level. The water in the tank is measured by the conductive probes and displaced via the LED indicators. At maximum-set capacity the pump is de-energized to automatically switch off, thereby stopping the inflow of water into the tank. The design approach involves three major stages which are: the power supply unit, the sensing unit, and the motoring and relay unit. The uniqueness of this work is the use of discrete components such as transistors to achieve water level control. This approach is more economical, simpler and easier to implement than the sophisticated programmable logic controllers and computerized microprocessors

Analiza drgań płyty trimorficznej pod kątem zoptymalizowanej ochrony przed uszkodzeniem

The dynamic response of a viscously damped rectangular trimorph plate subjected to a sinusoidally distributed load was investigated for simply- supported boundary conditions. The governing equation for the nonlinear deflection of the plate, which is first introduced in this paper, was derived based on the classical plate theory (CPT) and the classical laminate theory (CLT). The governing equation was solved using the Navier method and direct numerical integration. Optimised time-domain response plots for a trimorph plate made up of aluminium (Al), polyvinylidene fluoride (PVDF) and lead zirconate titanate (PZT) layers revealed that only three out of the six possible layer configurations are necessary for determining the best layer-stacking. In determining the best layer-stacking for the optimised dynamic response, three factors were considered namely: the stiffness, natural frequency and damping constant. Both of the Al/PVDF/PZT or Al/PZT/PVDF configurations were found to produce the best response qualities i.e. high elastic stiffness, high natural frequency and low viscous damping. Frequency-domain plots were generated to compare the nonlinear and linear responses and it was discovered that the effect of the nonlinearity predictably reduces the natural frequency of the trimorph plate. This study can be applied to the analysis of optimised damage mitigation of intelligent car bodies and safety critical structures which are subject to potentially destructive loading conditions.Przedstawiono badania dotyczące wiskotycznie tłumionej płyty trimorficznej poddanej sinusoidalnie rozłożonemu obciążeniu przy warunkach brzegowych typu swobodne podparcie. Wyprowadzono równanie ruchu płyty, pierwszy raz w tym artykule, opisujące nieliniowy efekt ugięcia na podstawie klasycznej teorii płyt (CPT) oraz klasycznej teorii laminatów (CLT). Równanie to rozwiązano metodą Naviera oraz bezpośrednim całkowaniem numerycznym. Zoptymalizowane wykresy odpowiedzi czasowych płyty wykonanej z aluminium (Al), polifluorku winylidenu (PVDF) oraz spieków cyrkonu i tytanu (PZT) wykazały, że tylko trzy z możliwych sześciu konfiguracji warstw trimorfu wystarczają do określenia najlepszego ułożenia warstw. Przy znajdowaniu najlepszej aranżacji warstw pod kątem zoptymalizowanej odpowiedzi dynamicznej płyty wzięto pod uwagę trzy czynniki: sztywność, częstość własną i stałą tłumienia.W tym kontekście najlepsze okazały się konfiguracje Al/PVDF/PZT oraz Al/PZT/PVDF – uzyskały najwyższą sztywność, największą częstość drgań własnych i najmniejszy współczynnik tłumienia. Wykresy otrzymane w dziedzinie częstości pozwoliły na porównanie odpowiedzi układu nieliniowego i zlinearyzowanego, ujawniając, zgodnie z przewidywaniami, że efekt nieliniowy zmniejsza częstość własną trimorfu. Wykazano także, że zaprezentowane badania mogą zostać zastosowane do analizy „inteligentnych” nadwozi samochodowych celującej w zoptymalizowane właściwości ze względu na ochronę przed uszkodzeniami oraz do krytycznych elementów bezpieczeństwa narażonych na potencjalne ryzyko zniszczenia

Effect of drill string rotation on the dynamic response of drilling risers

The effect of the rotation of a drill string on the response of a drilling riser has been studied. A governing equation for the flexural response that incorporates the effect of the drill string rotation is developed from first principles, and the resulting differential equation is found to have a variable coefficient, which is a function of the drill string rotational speed. Results simulated for the free vibration response show that the drill string rotation reduces the natural frequency and increases the amplitude of vibration of the drilling riser. The implication of these findings is that neglecting the effect of rotation of the drill string leads to under-estimation of the deflection and over-estimation of the natural frequency. Further analysis reveals that for a drilling riser of given dimensions, a drill string rotational speed exists at which the natural frequency of the drilling riser is theoretical equal to zero, and this rotational speed is the threshold rotational speed

Effect of grain size on the physicomechanical properties

In this study, locally available waste coconut (Cocos nucifera) shells (CSs) were investigated as possible replacement for asbestos-based brake pads. The CS-based brake pad was tested for its physicomechanical properties and compared with a commercial brake pad used as control sample. The results showed that (a) an improved interfacial bonding between the CS particles and the binder as the grain size decreases; (b) the 90 μm grain size sample had better physicomechanical properties than the control sample in all tests except the thermal conductivity and stability tests; and (c) the hardness, compressive strength, and density of the CS-based brake pad decreased with increasing grain size, whereas the absorption properties increased with increasing grain size. The study showed that further reduction of the grain size below 90 μm and matrix impregnation with metals of good thermal conductivity could provide significant improvements to properties of the CS-based brake pad