Search results for: vertical kiln dryer

Authors: Chaitanya R. Mali, V. Vinod, Ashwin W. Patwardhan

Abstract:

Design of long vertical steam generator (SG) tubes in nuclear power plant involves an understanding of different aspects of flow boiling phenomenon such as flow instabilities, flow regimes, dry out, critical heat flux, pressure drop, etc. The knowledge of the prediction of local thermal hydraulic characteristics is necessary to understand these aspects. For this purpose, the methodology has been developed which covers all the flow boiling regimes to model full range flow boiling phenomenon. In this methodology, the vertical tube is divided into four sections based on vapor fraction value at the end of each section. Different modeling strategies have been applied to the different sections of the vertical tube. Computational fluid dynamics simulations have been performed on a vertical SG tube of 0.0126 m inner diameter and 23 m length. The thermal hydraulic parameters such as vapor fraction, liquid temperature, heat transfer coefficient, pressure drop, heat flux distribution have been analyzed for different designed heat duties (1.1 MW (20%) to 3.3 MW (60%)) and flow conditions (10 % to 80 %). The sensitivity of different boiling parameters such as bubble departure diameter, nucleation site density, bubble departure frequency on the thermal hydraulic parameters was also studied. Flow instability has been observed at 20 % designed heat duty and 20 % flow conditions.

Keywords: thermal hydraulics, boiling, vapor fraction, sensitivity

Procedia PDF Downloads 119

Authors: Iyiola Olusola Oluwaleye, Samson A. Adeleye, Omojola Awogbemi

Abstract:

This paper reports an investigation of the comparative effects of drying on the quality of some leafy vegetables at three different temperatures namely: 50ᵒC, 60ᵒC and 70ᵒC. The vegetables investigated are spinach (Amaranthus cruentus); water leaf (Talinum triangulare); lettuce (Lactuca satuva); and fluted pumpkin (Telfaria occidentalis). These vegetables are available in abundance during raining season and are commonly consumed by average Nigerians. A convective dryer was used for the drying process at the stipulated temperatures which were maintained with the aid of a thermostat. The vegetable samples after washing was cut into smaller sizes of 0.4 cm-0.5 cm and loaded into the drying cage of the convective dryer. The daily duration of the drying is six hours from 9:00 am to 3:00 pm. The dried samples were thereafter subjected to microbial and proximate analyses. The result of the tests shows that the microbial load decreases as the drying temperature increases. As temperature increases, the moisture content and carbohydrate of all the samples decreases while the crude fiber, ash and protein increases. Percentage fat content decreases as drying temperature increases with the exception of fluted pumpkin. The shelf life of the vegetable samples increase with drying temperature, Spinach has the lowest shelf life followed by Fluted Pumpkin, followed by lettuce while Water Leaf has the highest shelf life at the three drying temperatures of 50ᵒC, 60ᵒC and 70ᵒC respectively.

Keywords: convective drying, leafy vegetables, quality, shelf life

Procedia PDF Downloads 235

Authors: Abel L. Masotla, Phesheya E. Dlamini, Vusumuzi E. Mbanjwa

Abstract:

Accurate quantification of the vertical distribution of soil organic carbon (SOC) in relation to land cover transformations, associated with shrub encroachment is crucial because deeper lying horizons have been shown to have greater capacity to sequester SOC. Despite this, in-depth soil carbon dynamics remain poorly understood, especially in arid and semi-arid rangelands. The objective of this study was to quantify and compare the vertical distribution of soil organic carbon stocks (SOCs) in shrub-encroached and open grassland sites. To achieve this, soil samples were collected vertically at 10 cm depth intervals under both sites. The results showed that SOC was on average 19% and 13% greater in the topsoil and subsoil respectively, under shrub-encroached grassland compared to open grassland. In both topsoil and subsoil, lower SOCs were found under shrub-encroached (4.53 kg m⁻² and 3.90 kgm⁻²) relative to open grassland (4.39 kgm⁻² and 3.67 kgm⁻²). These results demonstrate that deeper soil horizon play a critical role in the storage of SOC in savanna grassland.

Keywords: savanna grasslands, shrub-encroachment, soil organic carbon, vertical distribution

Procedia PDF Downloads 111

Authors: Pablo Kubo, Cassio Paiva, Adelino Ferreira

Abstract:

The main objective of this research study is to present the results of the influence of shock absorber condition, from a truck front suspension, on the vertical dynamic load applied on the pavement. For the measurements, it has been used a durability test track located in Brazil. The shock absorber conditions were new, used and failed with a constant load of 6 tons on the front suspension, the maximum allowed load for front axle according to Brazilian legislation. By applying relative damage concept, it is possible to conclude that the variation on the shock absorber conditions will significantly affect the load applied on the pavement. Although, it is recommended to repeat the same methodology in order to analyze the influence on the variation of the quarter car model variants.

Keywords: damage, shock absorber, vertical dynamic load, absorber

Procedia PDF Downloads 459

Authors: Sharmeelee Subramaniam, Muhd Harris Ramli, Fauziah Ahmad

Abstract:

The application of vacuum pressure to accelerate ground consolidation has been growing significantly in recent years. This ground improvement technique has its advantages, especially in areas where suitable fill is scarce, as it minimizes the surcharge fill height required for the preloading. A study was carried out to examine the response of soft subsoil subjected to vacuum consolidation in combination with embankment loading, surcharge preloading and PVD with two-way drainage. This paper shall describe a procedure to determine the optimum surcharge height and penetration depth of prefabricated vertical drains (PVD) where vacuum consolidation is combined with the use of PVD in soft clay deposits with two-way drainage.

Keywords: prefabricated vertical drain, soft soil, surcharge preload, vacuum consolidation

Procedia PDF Downloads 57

Authors: Emmanuel Omokhuale

Abstract:

A mathematical model is presented to study free convective boundary layer flow in a semi-infinite vertical cylinder with heat sink effect in a porous medium. The governing dimensional governing partial differential equations (PDEs) with corresponding initial and boundary conditions are approximated and solved numerically employing finite difference method (FDM) the implicit type. Stability and convergence of the scheme are also established. Furthermore, the influence of significant physical parameters on the flow characteristics was analysed and shown graphically. The obtained results are benchmarked with previously published works in order to access the accuracy of the numerical method and found to be in good agreement.

Keywords: free convection flow, vertical cylinder, implicit finite difference method, heat sink and porous medium

Procedia PDF Downloads 102

Authors: Md. Asaduzzaman

Abstract:

A Silicon-on-insulator (SOI) perfectly vertical fibre-to-chip grating coupler is proposed and designed based on engineered subwavelength structures. The high directionality of the coupler is achieved by implementing step gratings to realize asymmetric diffraction and by applying effective index variation with auxiliary ultra-subwavelength gratings. The proposed structure is numerically analysed by using two-dimensional Finite Difference Time Domain (2D FDTD) method and achieves 96% (-0.2 dB) coupling efficiency and 39 nm 1-dB bandwidth. This highly efficient GC is necessary for applications where coupling efficiency between the optical fibre and nanophotonics waveguide is critically important, for instance, experiments of the quantum photonics integrated circuits. Such efficient and broadband perfectly vertical grating couplers are also significantly advantageous in highly dense photonic packaging.

Keywords: diffraction grating, FDTD, grating couplers, nanophotonic

Procedia PDF Downloads 43

Authors: Mohammed Bakhit Kashoob, Mohammed Salim Al-Maashani, Ahmed Abdullah Al-Marhoon

Abstract:

Traffic calming measures are different design features or strategies used to reduce the speed of a traveling vehicle on a particular road. These calming measures are common on rural roads of Oman. Some of these measures are road speed limits, vertical deflections, horizontal deflections, and road signs. In general, vertical deflections such as rumble strips, road studs (cat’s eye), speed tables, and speed humps are widely used. In this paper, as vehicle speeding is a major cause of road traffic crashes and high fatalities in Oman, the effectiveness of existing traffic calming measures at current locations on rural roads is assessed. The study was conducted on the rural roads of Dhofar Governorate, which is located in the south of Oman. A special focus is given to the calming measures implemented on the mountain roads of Dhofar. It is shown that vertical deflection calming measures are effective in reducing vehicle speed to 20 to 40 kph, depending on the vertical deflection type and spacing. Calming measures are also proposed at locations with a high probability of traffic crashes based on the number of traffic crashes at these locations, road type, and road geometry.

Keywords: road safety, rural roads, speed, traffic calming measures, traffic crash

Procedia PDF Downloads 87

Authors: Moses. O. Eyankware, Benard I. Odoh, Omoleomo O. Omo-Irabor, Alex O. I. Selemo

Abstract:

Knowledge of hydraulic conductivity and transmissivity is essential for the determination of natural water flow through an aquifer. These parameters are commonly estimated from the analysis of electrical conductivity, soil properties and fluid flow data. In order to achieve a faster and cost effective analysis of aquifer parameters in Ochudo City in Abakaliki, this study relied on non-invasive geophysical methods. As part of this approach, Vertical Electrical Sounding (VES) was conducted at 20 sites in the study area for the identification of the vertical variation in subsurface lithology and for the characterization of the groundwater system. The area variously consists of between five to seven geoelectric layers of different thicknesses. Depth to aquifer ranges from 9.94 m-134.0 m while the thickness of the identified aquifer varies between 8.43 m and 44.31 m. Based on the electrical conductivity values of water samples collected from two boreholes and two hand-dug wells within the study area, the hydraulic conductivity was determined to range from 0.10 to 0.433 m/day. The estimated thickness of the aquifer and calculated hydraulic conductivity were used to derive the aquifer transmissivity. The results indicate that this parameter ranges from 1.58-7.56 m²/day with a formation factor of between 0.31-3.6.

Keywords: Asu river group, transmissivity, hydraulic conductivity, abakaliki, vertical electrical sounding (VES)

Procedia PDF Downloads 370

Authors: M. O. Oke, T. S. Workneh

Abstract:

Drying behaviour of blanched sweet potato in a cabinet dryer using different five air temperatures (40-80oC) and ten sweet potato varieties sliced to 5 mm thickness were investigated. The drying data were fitted to eight models. The Modified Henderson and Pabis model gave the best fit to the experimental moisture ratio data obtained during the drying of all the varieties while Newton (Lewis) and Wang and Singh models gave the least fit. The values of Deff obtained for Bophelo variety (1.27 x 10-9 to 1.77 x 10-9 m2/s) was the least while that of S191 (1.93 x 10-9 to 2.47 x 10-9 m2/s) was the highest which indicates that moisture diffusivity in sweet potato is affected by the genetic factor. Activation energy values ranged from 0.27-6.54 kJ/mol. The lower activation energy indicates that drying of sweet potato slices requires less energy and is hence a cost and energy saving method. The drying behavior of blanched sweet potato was investigated in a cabinet dryer. Drying time decreased considerably with increase in hot air temperature. Out of the eight models fitted, the Modified Henderson and Pabis model gave the best fit to the experimental moisture ratio data on all the varieties while Newton, Wang and Singh models gave the least. The lower activation energy (0.27-6.54 kJ/mol) obtained indicates that drying of sweet potato slices requires less energy and is hence a cost and energy saving method.

Keywords: sweet potato slice, drying models, moisture ratio, moisture diffusivity, activation energy

Procedia PDF Downloads 485

Authors: Ying Chen

Abstract:

Conservation Agriculture in a sustainable way of farming, as it brings many benefits, such as preventing soil from erosion and degradation, improving soil health, conserving energy, and sequestrating carbon. However, adoption of conservation agriculture has been progressing slowly in some part of the world due to some challenges. Among them, seeding in heavy crop residue is challenging, especially in corn production systems. Weed control is also challenging in conservation agriculture. This research aimed to investigate some technologies that can address these challenges. For crop residue management, vertical tillage and vertical seeding have been studied in multiple research projects. Results showed that vertical tillage and seeding were able to deal with crop residue through cutting residue into small segments, which would not plug seeder in the sub-sequent seeding. Vertical tillage is a conservation tillage system, as it leaves more than 30% crop residue on soil surface while incorporating some residue into the shallow soil layer for fast residue decomposition. For weed control, mechanical weeding can reduce chemical inputs in crop production. A tine weeder was studied for weed control during the early growing season of several field crops (corn, soybean, flax, and pea). Detail results of these studies will be shared at the conference.

Keywords: tillage, seeding, mechanical weeding, crop residue

Procedia PDF Downloads 39

Authors: H. Shokouhmand, A. Ghanami

Abstract:

Heat pipe is simple heat transfer device which combines the conduction and phase change phenomena to control the heat transfer without any need for external power source. At hot surface of heat pipe, the liquid phase absorbs heat and changes to vapor phase. The vapor phase flows to condenser region and with the loss of heat changes to liquid phase. Due to gravitational force the liquid phase flows to evaporator section.In HVAC systems the working fluid is chosen based on the operating temperature. The heat pipe has significant capability to reduce the humidity in HVAC systems. Each HVAC system which uses heater, humidifier or dryer is a suitable nominate for the utilization of heat pipes. Generally heat pipes have three main sections: condenser, adiabatic region and evaporator.Performance investigation and optimization of heat pipes operation in order to increase their efficiency is crucial. In present article, a parametric study is performed to improve the heat pipe performance. Therefore, the heat capacity of heat pipe with respect to geometrical and confining parameters is investigated. For the better observation of heat pipe operation in HVAC systems, a CFD simulation in Eulerian- Eulerian multiphase approach is also performed. The results show that heat pipe heat transfer capacity is higher for water as working fluid with the operating temperature of 340 K. It is also observed that the vertical orientation of heat pipe enhances it’s heat transfer capacity.

Keywords: heat pipe, HVAC system, grooved heat pipe, heat pipe limits

Procedia PDF Downloads 342

Authors: H. Shokouhmand, A. Ghanami

Abstract:

Heat pipe is a simple heat transfer device which combines the conduction and phase change phenomena to control the heat transfer without any need for external power source. At hot surface of the heat pipe, the liquid phase absorbs heat and changes to vapor phase. The vapor phase flows to condenser region and with the loss of heat changes to liquid phase. Due to gravitational force, the liquid phase flows to evaporator section. In HVAC systems, the working fluid is chosen based on the operating temperature. The heat pipe has significant capability to reduce the humidity in HVAC systems. Each HVAC system which uses heater, humidifier or dryer is a suitable nominate for the utilization of heat pipes. Generally, heat pipes have three main sections: condenser, adiabatic region, and evaporator.Performance investigation and optimization of heat pipes operation in order to increase their efficiency is crucial. In the present article, a parametric study is performed to improve the heat pipe performance. Therefore, the heat capacity of the heat pipe with respect to geometrical and confining parameters is investigated. For the better observation of heat pipe operation in HVAC systems, a CFD simulation in Eulerian- Eulerian multiphase approach is also performed. The results show that heat pipe heat transfer capacity is higher for water as working fluid with the operating temperature of 340 K. It is also showed that the vertical orientation of heat pipe enhances its heat transfer capacity.

Keywords: heat pipe, HVAC system, grooved heat pipe, CFD simulation

Procedia PDF Downloads 466

Authors: M. Heydari, A. Ghanami

Abstract:

Heat pipe is simple heat transfer device which combines the conduction and phase change phenomena to control the heat transfer without any need for external power source. At hot surface of heat pipe, the liquid phase absorbs heat and changes to vapor phase. The vapor phase flows to condenser region and with the loss of heat changes to liquid phase. Due to gravitational force the liquid phase flows to evaporator section.In HVAC systems the working fluid is chosen based on the operating temperature. The heat pipe has significant capability to reduce the humidity in HVAC systems. Each HVAC system which uses heater, humidifier or dryer is a suitable nominate for the utilization of heat pipes. Generally heat pipes have three main sections: condenser, adiabatic region and evaporator.Performance investigation and optimization of heat pipes operation in order to increase their efficiency is crucial. In present article, a parametric study is performed to improve the heat pipe performance. Therefore, the heat capacity of heat pipe with respect to geometrical and confining parameters is investigated. For the better observation of heat pipe operation in HVAC systems, a CFD simulation in Eulerian- Eulerian multiphase approach is also performed. The results show that heat pipe heat transfer capacity is higher for water as working fluid with the operating temperature of 340 K. It is also showed that the vertical orientation of heat pipe enhances it’s heat transfer capacity.

Keywords: heat pipe, HVAC system, grooved heat pipe, heat pipe limits

Procedia PDF Downloads 417

Authors: H. Shokouhmand, A. Ghanami

Abstract:

A heat pipe is simple heat transfer device which combines the conduction and phase change phenomena to control the heat transfer without any need for external power source. At a hot surface of the heat pipe, the liquid phase absorbs heat and changes to the vapor phase. The vapor phase flows to condenser region and with the loss of heat changes to the liquid phase. Due to gravitational force the liquid phase flows to the evaporator section. In HVAC systems, the working fluid is chosen based on the operating temperature. The heat pipe has significant capability to reduce the humidity in HVAC systems. Each HVAC system which uses the heater, humidifier, or dryer is a suitable nominate for the utilization of heat pipes. Generally, heat pipes have three main sections: condenser, adiabatic region, and evaporator. Performance investigation and optimization of heat pipes operation in order to increase their efficiency is crucial. In the present article, a parametric study is performed to improve the heat pipe performance. Therefore, the heat capacity of the heat pipe with respect to geometrical and confining parameters is investigated. For the better observation of heat pipe operation in HVAC systems, a CFD simulation in Eulerian-Eulerian multiphase approach is also performed. The results show that heat pipe heat transfer capacity is higher for water as working fluid with the operating temperature of 340 K. It is also showed that the vertical orientation of heat pipe enhances its heat transfer capacity.

Keywords: heat pipe, HVAC system, grooved heat pipe, heat pipe limits

Procedia PDF Downloads 404

Authors: H. Shokouhmand, A. Ghanami

Abstract:

Heat pipe is simple heat transfer device which combines the conduction and phase change phenomena to control the heat transfer without any need for external power source. At hot surface of heat pipe, the liquid phase absorbs heat and changes to vapor phase. The vapor phase flows to condenser region and with the loss of heat changes to liquid phase. Due to gravitational force the liquid phase flows to evaporator section. In HVAC systems the working fluid is chosen based on the operating temperature. The heat pipe has significant capability to reduce the humidity in HVAC systems. Each HVAC system which uses heater, humidifier or dryer is a suitable nominate for the utilization of heat pipes. Generally heat pipes have three main sections: condenser, adiabatic region and evaporator.Performance investigation and optimization of heat pipes operation in order to increase their efficiency is crucial. In present article, a parametric study is performed to improve the heat pipe performance. Therefore, the heat capacity of heat pipe with respect to geometrical and confining parameters is investigated. For the better observation of heat pipe operation in HVAC systems, a CFD simulation in Eulerian- Eulerian multiphase approach is also performed. The results show that heat pipe heat transfer capacity is higher for water as working fluid with the operating temperature of 340 K. It is also showed that the vertical orientation of heat pipe enhances it’s heat transfer capacity used in the abstract.

Keywords: heat pipe, HVAC system, grooved heat pipe, CFD simulation

Procedia PDF Downloads 380

Authors: H. Shokouhmand, A. Ghanami

Abstract:

Heat pipe is simple heat transfer device which combines the conduction and phase change phenomena to control the heat transfer without any need for external power source. At hot surface of heat pipe, the liquid phase absorbs heat and changes to vapor phase. The vapor phase flows to condenser region and with the loss of heat changes to liquid phase. Due to gravitational force the liquid phase flows to evaporator section.In HVAC systems the working fluid is chosen based on the operating temperature. The heat pipe has significant capability to reduce the humidity in HVAC systems. Each HVAC system which uses heater, humidifier or dryer is a suitable nominate for the utilization of heat pipes. Generally heat pipes have three main sections: condenser, adiabatic region and evaporator.Performance investigation and optimization of heat pipes operation in order to increase their efficiency is crucial. In present article, a parametric study is performed to improve the heat pipe performance. Therefore, the heat capacity of heat pipe with respect to geometrical and confining parameters is investigated. For the better observation of heat pipe operation in HVAC systems, a CFD simulation in Eulerian- Eulerian multiphase approach is also performed. The results show that heat pipe heat transfer capacity is higher for water as working fluid with the operating temperature of 340 K. It is also showed that the vertical orientation of heat pipe enhances it’s heat transfer capacity used in the abstract.

Keywords: heat pipe, HVAC system, grooved heat pipe, heat pipe limits

Procedia PDF Downloads 337

Authors: H. Shokouhmand, A. Ghanami

Abstract:

Heat pipe is simple heat transfer device which combines the conduction and phase change phenomena to control the heat transfer without any need for external power source. At hot surface of heat pipe, the liquid phase absorbs heat and changes to vapor phase. The vapor phase flows to condenser region and with the loss of heat changes to liquid phase. Due to gravitational force the liquid phase flows to evaporator section.In HVAC systems the working fluid is chosen based on the operating temperature. The heat pipe has significant capability to reduce the humidity in HVAC systems. Each HVAC system which uses heater, humidifier or dryer is a suitable nominate for the utilization of heat pipes. Generally heat pipes have three main sections: condenser, adiabatic region and evaporator.Performance investigation and optimization of heat pipes operation in order to increase their efficiency is crucial. In present article, a parametric study is performed to improve the heat pipe performance. Therefore, the heat capacity of heat pipe with respect to geometrical and confining parameters is investigated. For the better observation of heat pipe operation in HVAC systems, a CFD simulation in Eulerian- Eulerian multiphase approach is also performed. The results show that heat pipe heat transfer capacity is higher for water as working fluid with the operating temperature of 340 K. It is also showed that the vertical orientation of heat pipe enhances it’s heat transfer capacity.

Keywords: heat pipe, HVAC system, grooved Heat pipe, heat pipe limits

Procedia PDF Downloads 387

Authors: A. Ghanami, M.Heydari

Abstract:

Heat pipe is simple heat transfer device which combines the conduction and phase change phenomena to control the heat transfer without any need for external power source. At hot surface of heat pipe, the liquid phase absorbs heat and changes to vapor phase. The vapor phase flows to condenser region and with the loss of heat changes to liquid phase. Due to gravitational force the liquid phase flows to evaporator section. In HVAC systems the working fluid is chosen based on the operating temperature. The heat pipe has significant capability to reduce the humidity in HVAC systems. Each HVAC system which uses heater, humidifier or dryer is a suitable nominate for the utilization of heat pipes. Generally heat pipes have three main sections: condenser, adiabatic region and evaporator. Performance investigation and optimization of heat pipes operation in order to increase their efficiency is crucial. In present article, a parametric study is performed to improve the heat pipe performance. Therefore, the heat capacity of heat pipe with respect to geometrical and confining parameters is investigated. For the better observation of heat pipe operation in HVAC systems, a CFD simulation in Eulerian- Eulerian multiphase approach is also performed. The results show that heat pipe heat transfer capacity is higher for water as working fluid with the operating temperature of 340 K. It is also showed that the vertical orientation of heat pipe enhances it’s heat transfer capacity.used in the abstract.

Keywords: Heat pipe, HVAC system, Grooved Heat pipe, Heat pipe limits.

Procedia PDF Downloads 449

Authors: Chirine Aouichaoui, Mohamed Tounsi, Ines Mrizak, Zouhair Tabka, Yassine Trabelsi

Abstract:

The aim of this study was to provide percentile values for vertical jumping performances and anthropometric characteristics for athletic Tunisian children. One thousand and fifty-five athletic Tunisian children and adolescents (643 boys and 412 girls) aged 7-18 years were randomly selected to participate in our study. They were asked to perform squat jumps and countermovement jumps. For each measurement, a least square regression model with high order polynomials was fitted to predict mean and standard deviation of vertical jumping parameters and anthropometric variables. Smoothed percentile curves and percentile values for the 5th, 10th, 25th, 50th, 75th, 90th, and 95th percentiles are presented for boys and girls. In conclusion, percentiles values of vertical jumping performances and anthropometric characteristics are provided. The new Tunisian reference charts obtained can be used as a screening tool to determine growth disorders and to estimate the proportion of adolescents with high or low muscular strength levels. This study may help in verifying the effectiveness of a specific training program and detecting highly talented athletes.

Keywords: percentile values, jump height, leg muscle power, athletes, anthropometry

Procedia PDF Downloads 395

Authors: Anthony Khawaja, Jacques Prioux, Ghassan Maalouf, Rawad El Hage

Abstract:

The regular practice of physical activities characterized by significant mechanical stresses stimulates bone formation and improves bone mineral density (BMD) in the most solicited sites. The purpose of this study was to explore the relationships between maximum power and bone variables in a group of young adult men. Identification of new determinants of BMD, bone mineral content (BMC) and hip geometric indices in young adult men, would allow screening and early management of future cases of osteopenia and osteoporosis. Fifty-three young adult men (18 – 35yr) voluntarily participated in this study. Weight and height were measured, and body mass index was calculated. Body composition, BMC and BMD were determined for each individual by Dual-energy X-ray absorptiometry (DXA; GE Healthcare, Madison, WI) at whole body (WB), lumbar spine (L1-L4), total hip (TH), and femoral neck (FN). FN cross-sectional area (CSA), strength index (SI), buckling ratio (BR), FN section modulus (Z), cross-sectional moment of inertia (CSMI) and L1-L4 TBS were also evaluated by DXA. The vertical jump was evaluated using a field test (sargent test). Two main parameters were retained: vertical jump performance (cm) and power (w). The subjects performed three jumps with 2 minutes of recovery between jumps. The highest vertical jump was selected. Maximum power (P max, in watts) was calculated. Maximum power was positively correlated to WB BMD (r = 0.41; p < 0.01), WB BMC (r = 0.65; p < 0.001), L1-L4 BMC (r = 0.54; p < 0.001), FN BMC (r = 0.35; p < 0.01), TH BMC (r = 0.50; p < 0.001), CSMI (r = 0.50; p < 0.001), CSA (r = 0.33; p < 0.05). Vertical jump was positively correlated to WB BMC (r = 0.31; p < 0.05), L1-L4 BMC (r = 0.40; p < 0.01), CSMI (r = 0.29; p < 0.05). The current study suggests that maximum power is a positive determinant of BMD, BMC and hip geometric indices in young adult men. In addition, it shows also that maximum power is a stronger positive determinant of bone variables than vertical jump in this population. Implementing strategies to increase maximum power in young adult men may be useful for preventing osteoporotic fractures later in life.

Keywords: bone variables, maximum power, osteopenia, osteoporosis, vertical jump, young adult men

Procedia PDF Downloads 158

Authors: M. Heydari, A. Ghanami

Abstract:

Heat pipe is simple heat transfer device which combines the conduction and phase change phenomena to control the heat transfer without any need for external power source. At hot surface of heat pipe, the liquid phase absorbs heat and changes to vapor phase. The vapor phase flows to condenser region and with the loss of heat changes to liquid phase. Due to gravitational force the liquid phase flows to evaporator section. In HVAC systems the working fluid is chosen based on the operating temperature. The heat pipe has significant capability to reduce the humidity in HVAC systems. Each HVAC system which uses heater, humidifier or dryer is a suitable nominate for the utilization of heat pipes. Generally heat pipes have three main sections: condenser, adiabatic region, and evaporator. Performance investigation and optimization of heat pipes operation in order to increase their efficiency is crucial. In the present article, a parametric study is performed to improve the heat pipe performance. Therefore, the heat capacity of heat pipe with respect to geometrical and confining parameters is investigated. For the better observation of heat pipe operation in HVAC systems, a CFD simulation in Eulerian- Eulerian multiphase approach is also performed. The results show that heat pipe heat transfer capacity is higher for water as working fluid with the operating temperature of 340 K. It is also showed that the vertical orientation of heat pipe enhances it’s heat transfer capacity.used in the abstract.

Keywords: heat pipe, HVAC system, grooved heat pipe, heat pipe limits

Procedia PDF Downloads 365

Authors: Maritz Lourens Van Rensburg, Chantel Niebuhr

Abstract:

Utilizing all available renewable energy sources is an ever-growing necessity, this includes a newfound interest into hydrokinetic energy systems, which open the door to installations where conventional hydropower shows no potential. Optimization and obtaining high efficiencies are key in these installations. In this study a vertical axis Darrieus hydrokinetic turbine is designed and constructed to address certain drawbacks experience by axial flow horizontal axis turbines in an irrigation channel. Many horizontal axis turbines have been well developed and optimized to have high efficiencies but depending on the conditions experienced in an open channel, the performance of these turbines may be adversely affected. The study analyses how the designed vertical axis turbine addresses the problems experienced by a horizontal axis turbine while still achieving a satisfactory efficiency. To be able to optimize the vertical axis turbine, a computational fluid dynamics model was validated to the experimental results obtained from the power generated from a test turbine installation operating at various rotational speeds. It was found that an accurate validated model can be obtained through validation of generated power output.

Keywords: hydrokinetic, Darrieus, computational fluid dynamics, vertical axis turbine

Procedia PDF Downloads 91

Authors: Silumpa Suboonsan, Suwat Pattaramalai

Abstract:

In this paper, the performance of internet usage by using Vertical Handover (VHO) between cellular network and wireless local area network (WLAN) on Silom line Bangkok Mass Transit System (BTS) is evaluated. In the evaluation model, there is the WLAN on every BTS station and there are cellular base stations along the BTS path. The maximum data rates for cellular network are 7.2, 14.4, 42, and 100Mbps and for WLAN are 54, 150, and 300Mbps. The simulation are based on users using internet, watching VDOs and browsing web pages, on the BTS train from first station to the last station (full time usage) and on the BTS train for traveling some number of stations (random time). The results shows that VHO system has throughput a lot more than using only cellular network when the data rate of WLAN is more than one of cellular network. Lastly, the number of watching HD VDO and Full HD VDO is higher on VHO system on both regular time and rush hour of BTS travelling.

Keywords: vertical handover, WLAN, cellular, silom line BTS

Procedia PDF Downloads 444

Authors: Mohamed I. Alzarah

Abstract:

Passive dew harvesting and rainwater collection requires a very small financial investment meanwhile they can exploit a free and clean source of water in rural or remote areas. Dew condensation on greenhouse dryer cladding and assorted other surfaces was frequently noticed. Accordingly, this study was performed in order to measure the quantity of condensation in the arid regions. Dew was measured by using three different kinds of collectors which were glass of flat plate solar collector, tempered glass of photovoltaic (PV) and double sloped (25°) acrylic plexiglas of greenhouse dryer. The total amount of dew collection for three different types of collectors was measured during December 2013 to March 2014 in Alahsa, Saudi Arabia. Meteorological data were collected for one year. The condensate dew drops were collected naturally (before scraping) and by scraping once and twice. Dew began to condense most likely between 12:00 am and 6:30 am and its intensity reached the peak at about 45 min before sunrise. The cumulative dew yield on double-sloped test roof was varying with wind speed and direction. Results indicated that, wiping twice gave more dew yield compared to wiping once or collection by gravity. Dew and rain pH were neutral (close to 7) and the total mineralization was considerable. The ions concentration agrees with the World Health Organization recommendations for potable water. Using existing drying system for dew and rain harvesting cold provide a potable water source for arid region.

Keywords: PV module, flat plate solar collector, greenhouse, drying system, dew collection, water vapor, rainwater harvesting

Procedia PDF Downloads 303

Authors: James Banda, Jupiter Simbeye, Essau Chisale, Geoffrey Kanyerere, Kings Kamtambe

Abstract:

Improved solar tent dryers for processing small fish species were designed to reduce post-harvest fish losses and improve supply of quality fish products in the southern part of Lake Malawi under CultiAF project. A comparative analysis of the quality of Diplotaxodon (Ndunduma) from Lake Malawi processed in solar tent dryer and open sun drying was conducted using proximate analysis, microbial analysis and sensory evaluation. Proximates for solar tent dried fish and open sun dried fish in terms of proteins, fats, moisture and ash were 63.3±0.15% and 63.3±0.34%, 19.6±0.09% and 19.9±0.25%, 8.3±0.12% and 17.0±0.01%, and 15.6±0.61% and 21.9±0.91% respectively. Crude protein and crude fat showed non-significant differences (p = 0.05), while moisture and ash content were significantly different (p = 001). Open sun dried fish had significantly higher numbers of viable bacteria counts (5.2×10⁶ CFU) than solar tent dried fish (3.9×10² CFU). Most isolated bacteria from solar tent dried and open sun dried fish were 1.0×10¹ and 7.2×10³ for Total coliform, 0 and 4.5 × 10³ for Escherishia coli, 0 and 7.5 × 10³ for Salmonella, 0 and 5.7×10² for shigella, 4.0×10¹ and 6.1×10³ for Staphylococcus, 1.0×10¹ and 7.0×10² for vibrio. Qualitative evaluation of sensory properties showed higher acceptability of 3.8 for solar tent dried fish than 1.7 for open sun dried fish. It is concluded that promotion of solar tent drying in processing small fish species in Malawi would support small-scale fish processors to produce quality fish in terms of nutritive value, reduced microbial contamination, sensory acceptability and reduced moisture content.

Keywords: diplotaxodon, Malawi, open sun drying, solar tent drying

Procedia PDF Downloads 303

Authors: Abraham Finkelman

Abstract:

Computerized Surgical Guides have been proven to be a predictable way to perform dental implants, with a relatively high accuracy in comparison to a treatment plan. When using the CSG Bone supported, it allows us to make the necessary changes of the hard tissue prior to the implant placement and after the implant placement. The CSG gives us an accurate position for the drilling, and during the implant placement it allows us to alter the vertical position of the implant altering the final position of the abutment and avoiding any risk of any damage to the adjacent anatomical structures. Any Changes required to the bone level can be done prior to the fixation of the CSG using a reduction guide, which incur extra surgical fees and the need of a second surgical guide. Any changes of the bone level after the implant placement are at the risk of damaging the implant neck surface. The technique consists of a universal system that allows us to remove the excess bone around the implant sockets prior to the implant placement which then enables us to place the implant in the vertical position with accuracy as planned with the CSG. The systems consist of a hollow pin of different sizes and diameters. Depending on the implant system that we are using. Length sizes are from 6mm-16mm and a diameter of 2.6mm-4.8mm. Upon the completion of the drilling, the pin is then inserted into the implant socket-using the insertion tool. Once the insertion tool has unscrewed the pin, we can continue with the bone reduction. The bone reduction can be done using conventional methods upon the removal of all the excess bone around the pin. The insertion tool is then screwed into the pin and the pin is then removed. We now, have the new bone level at the crest of the implant socket which is our mark for the vertical position of the implant. In some cases, when we are locating the implant very close to anatomical structures, any form of deviation to the vertical position of the implant during the surgery, can cause damage to such anatomical structures, creating irreversible damages such as paresthesia or dysesthesia of the mandibular nerve. If we are planning for immediate loading and we have done our temporary restauration in base of our computerized plan, deviation in the vertical position of the implant will affect the position of the abutment, affecting the accuracy of the temporary prosthesis, extending the working time till we adapt the prosthesis to the new position.

Keywords: bone reduction, computer aided navigation, dental implant placement, surgical guides

Procedia PDF Downloads 308

Authors: Bao Shu-Feng, Lou Yan, Dong Zhi-Liang, Mo Hai-Hong, Chen Ping-Shan

Abstract:

For soft foundation filled by newly dredged mud, after improved by Vacuum Preloading Technology (VPT), the soil strength was increased only a little, the effective improved depth was small, and the ground bearing capacity is still low. To analyze the causes in depth, it was conducted in laboratory of several comparative single well model experiments of VPT. It was concluded: (1) it mainly caused serious clogging problem and poor drainage performance in vertical drains of high content of fine soil particles and strong hydrophilic minerals in dredged mud, too fast loading rate at the early stage of vacuum preloading (namely rapidly reaching-80kPa) and too small characteristic opening size of the filter of the existed vertical drains; (2) it commonly reduced the drainage efficiency of drainage system, in turn weaken vacuum pressure in soils and soil improvement effect of the greater partial loss and friction loss of vacuum pressure caused by larger curvature of vertical drains and larger transfer resistance of vacuum pressure in horizontal drain.

Keywords: newly dredged mud, single well model experiments of vacuum preloading technology, poor drainage performance of vertical drains, poor soil improvement effect, causes analysis

Procedia PDF Downloads 254

Authors: Amare Worku, Harikrishnan Muralidharan

Abstract:

The research for more environmentally friendly sources of energy is a result of growing environmental awareness. In this aspect, wind energy is a very good option and there are two different wind turbines, horizontal axis wind turbine (HAWT) and vertical axis turbine (VAWT). For locations outside of integrated grid networks, vertical axis wind turbines (VAWT) present a feasible solution. However, those turbines have several drawbacks related to various setups, VAWT has a very low efficiency when compared with HAWT, but they work under different conditions and installation areas. This paper reviewed numerous measurements taken to improve the efficiency of VAWT configurations, either directly or indirectly related to the performance efficiency of the turbine. Additionally, the comparison and advantages of HAWT and VAWT turbines and also the findings of the design methodologies used for the VAWT design have been reviewed together with efficiency enhancement revision. Most of the newly modified designs are based on the turbine blade structure modification but need other studies on behalf other than electromechanical modification. Some of the techniques, like continuous variation of pitch angle control and swept area control, are not the most effective since VAWT is Omni-directional, and so wind direction is not a problem like HAWT. Hybrid system technology has become one of the most important and efficient methods to enhance the efficiency of VAWT. Besides hybridization, the contra-rotating method is also good if the installation area is big enough in an urban area.

Keywords: wind turbine, horizontal axis wind turbine, vertical axis wind turbine, hybridization

Procedia PDF Downloads 65

Authors: Lucas Aerre, Wallesson Faria, Roberto Pimentel, Juliana Santos

Abstract:

An extremely disturbing and irritating element in the lives of people and organizations is the noise, the consequences that can bring us has a lot of connection with human health as well as financial and economic aspects. In order to improve the efficiency of buildings in Brazil in general, a performance standard was created, NBR 15.575 in which all buildings are seen in a more systemic and peculiar way, while following the requirements of the standard. The acoustic performance present in these buildings is one such requirement. Based on this, the present work was elaborated with the objective of evaluating through acoustic measurements the acoustic performance of vertical internal fences that are under the incidence of aerial noise of a building in the city of Brasilia-DF. A short theoretical basis is made and soon after the procedures of measurement are described through the control method established by the standard, and its results are evaluated according to the parameters of the same. The measurement performed between rooms of the same unit, presented a standardized sound pressure level difference (D nT, w) equal to 40 dB, thus being classified within the minimum performance required by the standard in question.

Keywords: airborne noise, performance standard, soundproofing, vertical seal

Procedia PDF Downloads 269