Timing Device Research Articles

Automation of bio-digester stirring system using locally available materials

An anaerobic bio-digester with electronically controlled stirring system was fabricated and tested using locally available materials. The experiment was conducted on a laboratory scale in Federal University of Technology Owerri. Cow dung obtained from an abattoir in Owerri and household biodegradable waste randomly collected from residential homes and eateries were used as the feedstock for this work. The feedstock was pre-fermented for a period of 10 days in an airtight bag before it was mixed with water in the ratio of 1:2 to form slurry that was fed into the digester. An Arduino system controlled timer with LED display screen was designed to control the on/off signal of a 2Hp electric motor powering the stirring arms. The programmable stirring timer device was set to run the electric motor for 30minutes at an interval of four hours to allow for even distribution of nutrients and microbes in the bio-digester. A control experiment was also carried out with non-automated stirring system. . It was observed that gas production in the control experiment reached its peak in fourteen days and the period was mired by fluctuating and less volume of gas production when compared to the main experiment where the gas production increased appreciably and steadily with maximum volume recorded on the tenth and eleventh day as contained in the results obtained. Model equations were generated for the two experiments and the wide variation in values of determinant factors (R2) in the two experiments is an indication that the automated stirring system with R2 = 0.97 performed better than the manually timed stirred trials with R2=0.88.

Computer Aided Design of Classic External Geneva Mechanism

Geneva mechanism is used as a mechanism for transforming rotary motion into intermittent motion and is able to achieve a precise movement and its lock, which makes it usable in many areas, particularly in timer devices, measurement devices, feed mechanisms, positioning mechanisms, pick-up and transport machinery, textile machinery etc. The studied literature showed that, although it has long been known, this mechanism is still interesting for contemporary researchers. The present paper proposes a method of synthesis and a computer-aided kinematic and dynamic analysis for this mechanism. Based on input data, it was developed a computer program that computes the dimensions of components of Geneva mechanism and determines velocity acceleration and displacement of Geneva wheel. The dimensional calculated data were also used to obtain 3D model of the mechanism.

Analysis of rigidity loss and deterioration from exposure in a decay test field of thermorectificated Eucalyptus grandis wood

The objective was to evaluate the elasticity dynamic modulus reduction (MOEd) and deterioration of E. grandis thermorectificated wood by exposure to environmental weathering. Six trees were used to obtain 14 logs of 2,4m, with seven from external (sapwood) and the others from internal (heartwood) part of the trunk. A total of 84 wood samples of 2,5x 5x 50cm were made, with half from the inner and the other from the external trunk portion. 14 treatments were evaluated with six replicates composed of thermorectificated wood submitted two differents times (2 and 4 hours) and three temperatures (200, 215 and 230°C). An ultrasound Stress Wave Timer device was used to evaluate MOEd and the mass measured by weighing. Samples remained in the decay test field for ten months, and monthly inspected and recorded to xylophogous organism�s occurrence. At the end of this period MOEd and mass were revaluated. The central portion of wood samples were more deteriorated, with mass losses and stiffness losses ranging from (8-56%) and (18-91%), respectively. Lower values ??were observed in the wood coming from the external portion, with mass losses and stiffness ranging from (3-10%) and (8-20%), respectively. The thermorectificated wood samples were more damaged by action the termites and less by the action of fungi, compared to controls.

Effects of heat-flux features on the differential scanning calorimetry curve of a thermoelastic martensitic transformation

The characterization of the heat effect of thermoelastic martensitic transformation is usually carried out in a heat-flux differential scanning calorimetry (DSC) device. The temperature of the sample during a DSC cycle differs from the temperature of the reference. This means that the measured heat flow covers both the latent heat and the heat quantity needing to heat up (cool down) the sample. The later heat quantity is the temperature balancing between the sample and the reference. Furthermore, the temperature balancing is still measured when the transformation is finished. According to this, using the peak endpoint to determine the transformation (austenite or martensite) finish temperature gives an error, which depends on the device's time constant. The temperature balancing is sensitive on the rate of heating (and cooling) and the mass of the sample. When evaluating DSC curves of heat-flux DSC, one must take into account these facts not to get false results. Cu–Al–Ni single crystal was examined to show the above-mentioned phenomena, and an evaluation program was developed to improve the quantitative analyzing of DSC peaks.

Stopwatch Calibrations, Part III: The Time Base Method

The Time Base Method for calibrating stopwatches and/or timers involves determining the frequency of the device's time base using calibrated, traceable standards. Two non-contact methods for this m...