Performance Evaluation of a Small-Scale Mechanical Fish Feeder

The performance evaluation of an existing mechanical fish feeder was carried out. Floating feeds of sizes 2 mm, 4 mm, and 6 mm at constant moisture content of 13 % were fed into the feeder. The feeder was powered by a 3-phase, 1.5 kW reducing gear electric motor at speed 40 rpm, 50 rpm, 60 rpm, 70 rpm and 80 rpm machine. It was observed that the horizontal screw conveyor effectively transported the material from the hopper to the discharged point. The results obtained from the tests showed an optimal performance of the machine at speed 50 rpm with dispensing efficiency of 93.1 % for 2 mm feed size, while the throughput was 75.76 kg/h at motor speed of 80 rpm also for the 2 mm fish feed size. The ANOVA at p ≤ 0.05 showed that machine speed has significant effect on its dispensing efficiency and the throughput capacity. The cost of production of the mechanical fish feeder was ₦262,300 which made it affordable for young entrepreneurs.

Viscoelastic creep behavior of surface- and inner-layers of sugi boxed-heart timber under various temperatures

This study was conducted to investigate the rheological behavior of sugi boxed-heart timber under constant moisture content (MC) using a cantilever creep test. The focus of the study was the effect of temperature on viscoelastic creep behavior of surface- and inner-layer specimens of the timber. The specimens with dimensions of 75 mm in length, 25 mm wide, and 3 mm thick were prepared. A cantilever creep test with an effective span of 40 mm was conducted under a constant temperature of 20, 65, 80, and 95 °C. The equilibrium moisture content (EMC) of the specimens was set to around 12% at each temperature. A load representing 20% of rupture load of the specimens at each temperature was applied to their free-end and strain gauges were bonded at the fourth span (10 mm) on the upper and bottom surfaces of the specimens. Loading and unloading duration were set for 300 and 180 min, respectively, and a four-element Burgers model was used to model the creep behavior of the timber. It was found that temperature had significant effects on the creep properties of the timber. The surface strain and creep compliance of the surface- and inner-layer specimens tended to increase as the temperature increased. Creep compliance of the surface-layer specimen was higher than that of the inner-layer specimen at each temperature. Fitting the experimental data with the Burgers model used in this study shows good agreement and it was found that elastic (instantaneous) and viscoelastic (delayed) creep compliance of all the specimens tended to increase as the temperature increased. On the other hand, the viscosity of the dashpot element of both the Maxwell and the Kelvin unit tended to decrease as the temperature increased. Although different in magnitude, the creep-recovery compliance parameters had the same tendency as the creep compliance parameters.

Parameters affecting biomass drying during combustion in moving grate furnaces

The most efficient way so far to extract energy from renewable sources is combustion of solid fuel. Solid fuel furnaces of moderate capacity (5–10 MW) equipped with reciprocating grates are most popular. Grate combustion is a well-developed technology; however, to burn biofuel in this type of furnaces in the optimal and safe way, the fuel must be of high quality and have at least constant moisture content. However, increasing demand for biofuel results in increasing prices. To remain in the market and to stay competitive, heat producers choose to utilise moist biofuel of lower quality, whose moisture content can vary and reach up to 60% wt. The burning on the grate of such biofuel is complicated as the drying process occupies most of the space in the furnace. The purpose of this work was to analyse processes taking place in a furnace, such as: primary air supply, influence of flue gas recirculation and radiation from hot surfaces of the furnace to biofuel drying. Analysis of the data obtained would provide technical decisions facilitating optimal fuel combustion in a furnace without additional investments. Analysis of biofuel drying was performed in an experimental setup with a fixed fuel bed. The experiments were performed with wood chips and four different drying fluid temperatures. The results of experimental studies have shown that the drying rate of biofuels upper layers is strongly influenced by radiation from hot surfaces and the moisture content of the sample decreases by 18% wt.

Orthotropic mechano-sorptive creep behavior of Chinese fir during the moisture adsorption process determined in tensile mode via dynamic mechanical analysis (DMA)

The orthotropic viscoelastic creep (VEC) at a constant moisture content (MC) and mechano-sorptive creep (MSC) during the adsorption process were examined for Chinese fir (Cunninghamia lanceolata) under tension at 20, 40, 60 and 80% relative humidity (RH) (30°C). Free swelling was performed on matched specimens based on the strain partition assumption to better understand the characteristics of the mechano-sorptive (MS) phenomenon. Expansion, elastic and time-dependent creep behaviors of radial (R) and tangential (T) specimens were affected by the MC to a higher degree than those of the longitudinal (L) specimen. A higher proportion of elastic strain in total strain was found in the L specimen as compared with transverse specimens, regardless of VEC and MSC. The RH level had a greater effect on relaxation behavior in the L specimen for MSC. According to the three tests, expansion mainly dominated the creep strain during adsorption, especially for the L specimen. The MS strain exerted more influence on transverse specimens and had less contribution to the L specimen. Moreover, under all RH isohume (RHI) conditions, the unstable state contributed to MS strain diminishing as MC approached equilibrium moisture content (EMC). A shorter adsorption time to a new equilibrium state was achieved at the expense of intensifying the unstable state of the wood cell wall.

Utilization of a vinyl based copolymer for improvement of a kaolin type clay

Geopolymers are obtained by use of alteration of chemical composition and crystal structures of different minerals. Use of geopolymer is an effective and environmental friendly solution in stabilization of clayey soil. The vinyl based copolymer is used as an agent as dust controller, highway soil stabilizer, asphalt admixture, concrete production, etc. In this study, strength of a clay is improved by use of a commercial geopolymer. In this regard, soil was amended with polymer ranging among 0 % to 4 %, by volume of dry soil. Unconfined compression and oedometer tests were carried out to evaluate the effects of temperature, initial water content, compaction energy on strength and compression properties of a clay soil - within an experimental framework. The results revealed that, temperature has a considerable effect on geopolymerization. Besides, under constant moisture content during curing, increasing geopolymer content and curing period causes a slight increase in strength of specimens.

Moisture and temperature in a proppant-enveloped silt block of a recharge dam reservoir: Laboratory experiment and 1-D mathematical modelling

Mosaic 3-D cascade of parallelepiped-shaped silt blocks, which sandwich sand- lled cracks, has been discovered in the eld and tested in lab experiments. Controlled wetting-drying of these blocks, collected from a dam reservoir, mimics field ponding-desiccation conditions of the topsoil layer subject to caustic solar radiation, high temperature and wind, typical in the Batinah region of Oman. In 1-D analytical modelling of a transient Richards’ equation for vertical evaporation, the method of small perturbations is applied, assuming that the relative permeability is Avery-anov’s 3.5-power function of the moisture content and capillary pressure is a given (measured) function. A linearized advective dispersion equation is solved with respect to the second term in the series expansion of the moisture content as a function of spatial coordinates and time. For a single block of a nite thickness we solve a boundary value problem with a no- ow condition at the bottom and a constant moisture content at the surface. Preliminary comparisons with theta-, TDR- probes measuring the moisture content and temperature at several in-block points are made. Results corroborate that a 3-D heterogeneity of soil physical properties, in particular, horizontal and vertical capillary barriers emerging on the interfaces between silt and sand generate eco-niches with stored soil water compartments favourable for lush vegetation in desert conditions. Desiccation significantly increases the temperature in the blocks and re-wetting of the blocks reduces the daily average and peak temperatures, the latter by almost 15°C. This is important for planning irrigation in smartly designed soil substrates and sustainability of wild plants in the region where the top soil peak temperature in the study area exceeds 70°C in Summer but smartly structured soils maintain lash vegetation. Thee layer of dry top-blocks acts as a thermal insulator for the subjacent layers of wet blocks that may host the root zone of woody species.

Physical properties of cumin and caraway seeds

Physical properties of cumin and caraway seeds were measured and compared at constant moisture content of 7.5% w.b. The average thousand mass of grain, mean length, mean width, mean thickness, equivalent diameter, geometric mean diameter, surface area, volume, sphericity, aspect ratio, true density, bulk density and porosity were measured for cumin and caraway. There are significant differences (p<0.01) in most physical properties of cumin and caraway, except porosity and sphericity

Influence of Different Fertilization Level of Zinc Sulphate and Plant Density on the Breakage Susceptibility of Triticale Seeds

In order to determine the effects of different fertilization level of zinc sulphate and plant density on the breakage susceptibility of triticale seeds an experiment was conducted during 2011 growing season, at the experimental research station of Lorestan University, Iran. A factorial experiment was conducted with 3×3 treatments and three replications in a completely randomized block design (CRBD). Factors included three plant densities (200, 300 and 400 plants/m2) and three levels of zinc sulphate (0 - control, 40 and 60 kg/ha). The harvested seeds were then subjected to impact energies of 0.05 and 0.1 J at constant moisture content of 15% using an impact test apparatus. The analysis of variance showed that fertilization level of zinc sulphate (at the 1% probability level), plant density (at the 5% level) and interaction between two variables (at the 5% level) significantly influenced breakage susceptibility of triticale seeds. The average values of percentage breakage of seeds decreased from 32.592 to 16.9268% as the fertilization level of zinc sulphate increased from 0 to 60kg/ha. As the plant density increased from 200 to 400 plants/m2 the percentage breakage of seeds decreased from 27.942 to 21.350%. Increasing the impact energy from 0.05 to 0.1 J caused an increase in the percentage breakage of seeds from 14.07 to 36.9%.