Physics

Abstract Tracking objects in real-time has a variety of applications in many fields. Optical flow based tracking is one such tracking mechanism which can track moving objects even under complex backgrounds and different light conditions. The research presented in this paper discusses the feasibility of using optical flow to track moving objects captured in a camera view, to extract basic information related to the objects.

Thin-layer drying characteristics of paddy were examined within the relative humidity range from 30% to 60%. A test chamber has been constructed with Perspex and continuously flushed with low humid air to control the inside relative humidly at required levels and several homogeneous thin layer paddy samples were dried inside the chamber. BG 300, BG 352 and BG 357 paddy varieties developed by Rice Research and Development Institute, Bathalegoda, Sri Lanka have been used in this study. Normalized drying data was transformed into dimensionless parameter called Moisture Ratio, and fitted with four semi-theoretical models. Correlation coefficients, standard errors and residual plots were used as criteria for evaluating the goodness-of-fit. Of the models used the two-term exponential model was found to fit well with the experimental data and is recommended as the thin-layer drying model for paddy. Drying constant of the dominant drying process of BG 300 varies from 9.31x10 -5 s -1 to 8.41...

This work reports a design and construction of a drying chamber powered by parabolic trough solar concentrator. The constructed drying chamber is made of thin aluminum sheet material with two compartments; one is for installation of standby electrical heaters and the other is for material pallet. The chamber is powered by a parabolic trough solar concentrator with aperture area of 5 m 2. An electrical heater backup was employed to maintain the temperature inside the chamber at a given constant temperature when solar energy is not sufficient. The maximum variation of the temperature inside the chamber along the length of the material pallet was found to be 8 °C when the chamber is powered by solar concentrator. This variation was 16 °C when the chamber is powered by electric heaters. Temperature variation across the vertical direction is almost constant when the chamber is empty and a 10 % drop in temperature was observed over the material pallet relative to the other areas. The drying characteristics of samples of cabbage, boiled rice, scraped coconut, dry leaves and grass for different temperatures obtained using the drying chamber are found to be fitted well with the page model and the corresponding drying constants at 80 °C are found to be 0.0197, 0.0139, 0.0319, 0.0296, 0.0564 respectively.

Firmnesses of farm fresh samples of three tomato (Lycopersicon esculentum) varieties grown in Sri Lanka, named, Maheshi, HF-2 and T-146 were studied. The firmness of the tomatoes was measured using Effegi type Bishop FT 327 firmness tester. Measurements were carried out for three consecutive days after plucking them from plants. Ever since tomatoes were harvested, the firmness was found to decrease daily. Throughout the three-day period of shelf life, all three varieties registered a higher firmness value for sun-shaded side than the corresponding firmness value for the sun-exposed side. Among the three tomato varieties, Maheshi at all times registered the highest firmness value while T-146 variety registered the lowest. Also the Maheshi variety indicated the lowest rate of loss-of-firmness with time. As a result, the first officially released hybrid tomato variety Maheshi stands out with its superior and promising quality over the other two varieties, throughout the handling process, storage and shelf life in marketing chain. (The firmness measurements were made on peeled-off tomatoes, with a plunger of diameter 11.3 mm).

The mixed kitchen garbage which is disposed from houses, hotels etc. mainly cause to lot of environment and hygienic problems. Mixed kitchen garbage generally contains higher moisture content. By drying, it is possible to convert them to some useful products while avoiding some of the problems arisen. This research investigates the drying behaviours of mixed kitchen garbage and its' constituents under three different methods namely drying in a low humid and high temperature, in an electrical oven and under the sun. Two-term exponential single layer drying model was found to be the best model to explain the behaviour of drying in a low humid, high temperature the drying chamber. The diffusion constants for the samples of tomato, rice , papaw, scraped coconut, cabbage, dry leaves, grass, mixed kitchen garbage 1, mixed kitchen garbage 2 and mixed kitchen garbage 3 were ; (2.026, 2.702, 2.871, 3.715, 2.702, 11.652, 9.625, 2.026, 2.026 and 2.702) x 10-9 m 2 h-1 respectively. Newton single layer drying model was the best model to explain the behaviour where drying in an electrical oven. The respective diffusion constants for the samples of tomato, rice , papaw, scraped coconut, dry leaves, grass, mixed kitchen garbage 1and mixed kitchen garbage 2 were ;(3.040, 2.720, 5.066, 3.715, 2.533, 3.208, 3.715and 2.208) x10-9 m 2 h-1 respectively. Henderson-Pabis single layer drying model was the best model which explain the drying under the sun. The corresponding diffusion constants for the samples of tomato, rice , papaw, scraped coconut, dry leaves, grass, mixed kitchen garbage 1and mixed kitchen garbage 2 were ;(0.338, 0.675, 0.675, 1.857, 1.520, 1.351, 0.507 and 1.013) x10-9 m 2 h-1 respectively.

Measuring tilt and vibration are two of the major applications of accelerometers. An experimental method to calibrate a commercially available 2D accelerometer (ADXL202JQC) as a tilt and a vibration measuring device is discussed in this publication. Calibration of tilt measurements (measuring acceleration due to the gravity-the static case) was done by rotating the accelerometer in a vertical plane. Also the effect of minor inclinations of the plane rotation of this experiment was investigated and observed to be minute. Based on the calibration for the static case, the accelerometer was tested in a dynamic case. A known type of motion; the motion of a tip of a cantilever, was used to test the calibration of the accelerometer for the dynamic case. Motion of the tip of a cantilever was considered as a damping oscillation thus the variation of acceleration of the tip of the cantilever was considered a decaying sinusoidal. The measurements obtained through accelerometer agreed to this proposed model with R 2 values in the range of 0.93 to 0.98. The frequency of oscillation of the cantilever was varied by changing the length of the cantilever. The periods of oscillation obtained by the accelerometer agreed with the same values obtained from a stroboscope to maximum percentage deviation of approximately 3%.

The mixed kitchen garbage which is disposed from houses, hotels etc. mainly cause to lot of environment and hygienic problems. Mixed kitchen garbage generally contains higher moisture content. By drying, it is possible to convert them to some useful products while avoiding some of the problems arisen. This research investigates the drying behaviours of mixed kitchen garbage and its' constituents under three different methods namely drying in a low humid and high temperature, in an electrical oven and under the sun. Two-term exponential single layer drying model was found to be the best model to explain the behaviour of drying in a low humid, high temperature the drying chamber. The diffusion constants for the samples of tomato, rice , papaw, scraped coconut, cabbage, dry leaves, grass, mixed kitchen garbage 1, mixed kitchen garbage 2 and mixed kitchen garbage 3 were ; (2.026, 2.702, 2.871, 3.715, 2.702, 11.652, 9.625, 2.026, 2.026 and 2.702) x 10-9 m2h-1 respectively. Newton sin...

Firmnesses of farm fresh samples of three tomato (Lycopersicon esculentum) varieties grown in Sri Lanka, named, Maheshi, HF-2 and T-146 were studied. The firmness of the tomatoes was measured using Effegi type Bishop FT 327 firmness tester. Measurements were carried out for three consecutive days after plucking them from plants. Ever since tomatoes were harvested, the firmness was found to decrease daily. Throughout the three-day period of shelf life, all three varieties registered a higher firmness value for sun-shaded side than the corresponding firmness value for the sun-exposed side. Among the three tomato varieties, Maheshi at all times registered the highest firmness value while T-146 variety registered the lowest. Also the Maheshi variety indicated the lowest rate of loss-of-firmness with time. As a result, the first officially released hybrid tomato variety Maheshi stands out with its superior and promising quality over the other two varieties, throughout the handling proces...

Development and testing of an optical technique for evaluating the shape of reflective parabolic trough is reported. This method consists of a single axis rotatable He-Ne laser with a vernier scale and a target plane with a millimeter scale. The parabolic reflector is scanned by the laser beam vertically with known angles and the positions of the reflected beam hit on the target plane are recorded. The deformed angle of the reflective surface is then calculated using these data and the variation of the focal length is finally derived. The surface quality of a prototype Parabolic Tough Concentrator (PTC) was evaluated using this technique at three different positions along the reflector, the testing method developed found to be acceptable as it produced consistent data over different locations of surface. Deviations up to 90 mm in the focal length were detected using the method and the results revealed that the shape of the parabola of this PTC was significantly deformed in the first quarter of the vertical direction of the shape and the other part is of the acceptable level in view of the large acceptance angle of the Heat Collecting Element (HCE).

A theoretical investigation of the effect of wind on parabolic trough type solar energy concentrator (PTC) with reference to geographical and metrological parameters of Hambantota (semi-desert zone) and behavior of structure on that wind load are reported. It has been found that the maximum daytime wind speed reported (on non-disastrous situation) is around 8.3 m s-1 which is a Fresh breeze situation in Hambantota. Beaufort number 5 has been assumed for calculating the wind load and Terrain factor of 1/7 (open country) has been selected after considering nature of the terrain of semi-desert zones of Sri Lanka. Maximum drag coefficient for the shape of parabola used in the study was found from tables as 2.0. The mean wind load applied on the PTC of dimensions 4.5 m × 4.8 m and the aperture area of 22.3 m 2 has been calculated is by assuming quasi-steady conditions and the value was found to be 1.36 kN. Weather gust factor is also included in order to deal with more practical situations, and it is found that the maximum wind load and torque are 3.19 kN and 3.64 kNm respectively for a gust factor of 1.53. It has been found that the maximum load calculated with the gust factor is compatible with the values obtained by assuming light gale conditions (wind speed around 12.7 m s-1) with a laminar flow. The structure of the parabolic trough has five main trusses to withstand the aforesaid maximum wind load. 1/5 of that load is applied on one main truss to calculate the strain 6 × 10-5 , stress 11.9 MPa and total deformation 1.12.mm on the software simulation.

Measuring tilt and vibration are two of the major applications of accelerometers. An experimental method to calibrate a commercially available 2D accelerometer (ADXL202JQC) as a tilt and a vibration measuring device is discussed in this publication. Calibration of tilt measurements (measuring acceleration due to the gravity-the static case) was done by rotating the accelerometer in a vertical plane. Also the effect of minor inclinations of the plane rotation of this experiment was investigated and observed to be minute. Based on the calibration for the static case, the accelerometer was tested in a dynamic case. A known type of motion; the motion of a tip of a cantilever, was used to test the calibration of the accelerometer for the dynamic case. Motion of the tip of a cantilever was considered as a damping oscillation thus the variation of acceleration of the tip of the cantilever was considered a decaying sinusoidal. The measurements obtained through accelerometer agreed to this proposed model with R 2 values in the range of 0.93 to 0.98. The frequency of oscillation of the cantilever was varied by changing the length of the cantilever. The periods of oscillation obtained by the accelerometer agreed with the same values obtained from a stroboscope to maximum percentage deviation of approximately 3%.

Cellulose acetomyristates of varied composition were studied. The sample volume abnormally increases in high-temperature stretching and after swelling in benzene. Cellulose acetomyristates can be used as membranes for separating aromatic and aliphatic hydrocarbons.

The versatility of the Finger-Feel-Firmness (FFF) test method has been proved with a series of panel evaluations. Judgment of the panel on the pattern of the variation of FFF, agrees with that of the author. An individual can be trained to monitor the pattern of variation of FFF. Absolute values of FFF however, depend on the personal forcesensitivity of the individual. Degradation of the firmness due to squeezes made in FFF test itself has also been investigated. Retail market tomatoes registered a rate of loss of average FFF from 60 to 65 g/d and the level of ripeness of the sample had no significant effect on this rate. On repeated squeezing in the FFF test itself, the rate of loss of FFF was only about 4 g/squeeze. Development in red colour with shelf-life in less-ripe tomatoes was nearly 3 times faster compared to 0.5 rank/d in red-ripe tomatoes. However, the loss of FFF with the development in red colour in less-ripe tomatoes was 40 g/rank and it was more or less 3 times slower compared to 121 g/rank in red-ripe tomatoes. It was clear that the natural deterioration does about 15 times severe damage to the whole fruit, compared to the induced local damage by squeezing in the FFF test. With knowledge of colour and FFF value, it is possible to estimate the expected shelf life of tomatoes. Tomatoes ripened up to colour rank 10 would spend a shelf-life till they reach a range of FFF as low as 100 to 200 g (subject to personal force-sensitivity, tomato variety and post-harvest management methods.

Activity of cloud-to-ground lightning flashes observed during the monsoon thunderstorms over Sri Lanka with a lightning locating system consisting of two direction finders (DF) is presented. The Northeast monsoon produced over 884 cloud-to-ground flashes with a peak lightning rate of 96 flashes per hour whereas Southwest monsoon produced 3,294 flashes with a peak rate of 104 flashes per hour. A relative flash density maximum of 198 flashes per 28×28 km 2 was observed over Ratnapura area (6.68N, 80.40E). The percentage of positive flashes and average peak lightning current values for negative flashes are found to be 6.4% and 36 kA respectively for the Northeast monsoon period and 1.7% and 40 kA respectively for the Southwest monsoon period for the flashes that struck within 10-250 km range. No significant difference in average peak lightning current values were observed for the negative and positive flashes in both monsoons.

For studying and controlling the vibration effects present at vehicular road transportation, the quantitative estimation and laboratory simulation of the same becomes vital. Using an accelerometer, the vibration acceleration was measured in terms of power spectral density (PSD) in dB/Hz unit. Average of the maximum vertical vibration (PSDmax) levels produced by the truck over the time of experiment were 0.005 dB/Hz, 0.01 dB/Hz and 0.05 dB/Hz at the front, middle and rear of the truck-bed respectively. Vertical vibration acceleration levels present at actual vehicular road transportation were simulated at the laboratory using a fabricated electro-dynamic vibrator. PSDmax levels met at the actual road transportation by truck were simulated at the laboratory by varying the eccentric mass and the loaded-weight of the vibrator. Eccentric mass adjusted in between 200 g and 300 g permits generation of PSDmax levels of interest on the vibrator at no-load. Loading a weight in the range from ...

Chlorophyll content of a water sample is used as an indirect estimate for the nutrient level of the sample. Optical spectroscopic techniques are widely used to estimate chlorophyll contents of water samples. However, in a complex environment such an urban lake, there are many other pollutant constituent exists. Hence it is difficult to determine the pollutant level only by investigating the chlorophyll signatures. A study is carried out by collecting water samples from different spatial location of Beira Lake, Colombo (29o 52’ N, 77o 53’ E, 0.0001 m above mean sea level) and fluorescence spectrum excited at 405 nm and absorption spectrum were obtained for each samples. Despite spectral signatures of chlorophyll, spectral signatures of different polluted constituents were observed in both fluorescence and absorption spectra of the every sample. Obtained data set was compressed using singular value decomposition and used first two components which carry 62 % of information. It was fou...

Parameters of the Road-Vehicle-Load system influence the vibration effects generated at vehicular road transportation. Vertical vibration acceleration (PSDmax) experienced by the tomato boxes and tomatoes within the box was studied using the popular transport means in Illukkumbura area in Matale. The road quality was estimated using the International Road Roughness Index (IRI). Fully loaded Mitsubishi Canter truck at an average speed of 20 kmh-1 on a road rated at IRI between 2 to 3.5 mm/m registered increasing trend in the PSD of vibration from the front side towards the rear side of the truck in the horizontal direction. The observed average PSD values are in the approximate ratio, front : middle : rear ≈ 1 : 3: 6. Also the PSD of the vibration was found to be amplified from the bottom stack towards the topmost stack in the vertical direction. The observed average PSD values at 1st, 2nd, 3rd, and 4th stacks are in the approximate ratio, 1 : 1 : 1.5 : 2.5. PSD of vibration was stud...

This thesis describes the development of a gas scintillation drift counter as a high counting rate X-ray detector. The new device is a modified version of the gas scintillation counter which is capable of working in a digital mode at a quite high rate without producing space charge effects. A gas scintillation drift counter has been built to investigate its behaviour using a gas mixture of argon and nitrogen. Scintillation and transport properties of the gas mixture have been studied using an Am(^241) α-particle source and a (Fe(^55)) 5.9 keV radioactive X-ray source in order to obtain optimum relative compositions of argon and nitrogen. The effects of various operating parameters on the energy resolution of the counter and the characteristics of output pulses have been extensively studied. When deciding on the counter parameters and operating conditions, a special emphasis has been placed on conditions which produce a minimum of space charge around the anode, and small pulse-widths...