Abstract: In Swedish tunnel construction, a critical issue that has been repeatedly acknowledged is corrosion and, consequently, failure of the rock bolts in rock support systems. The defective installation of rock bolts results in the formation of cavities in the cement mortar that is regularly used to fill the area under the dome plates. These voids allow for water-ingress to the rock bolt assembly, which results in corrosion of rock bolt components and eventually failure. In addition, the current installation technique consists of several manual steps with intense labor works that are usually done in uncomfortable and exhausting conditions, e.g., under the roof of the tunnels. Such intense tasks also lead to a considerable waste of materials and execution errors. Moreover, adequate quality control of the execution is hardly possible with the current technique. To overcome these issues, a non-shrinking/expansive cement-based mortar filled in the paper packaging has been developed in this study which properly fills the area under the dome plates without or with the least remaining cavities, ultimately that diminishes the potential of corrosion. This article summarizes the development process and the experimental evaluation of this technique for the installation of rock bolts. In the development process, the cementitious mortar was first developed using specific cement and shrinkage reducing/expansive additives. The mechanical and flow properties of the mortar were then evaluated using compressive strength, density, and slump flow measurement methods. In addition, isothermal calorimetry and shrinkage/expansion measurements were used to elucidate the hydration and durability attributes of the mortar. After obtaining the desired properties in both fresh and hardened conditions, the developed dry mortar was filled in specific permeable paper packaging and then submerged in water bath for specific intervals before the installation. The tests were enhanced progressively by optimizing different parameters such as shape and size of the packaging, characteristics of the paper used, immersion time in water and even some minor characteristics of the mortar. Finally, the developed prototype was tested in a lab-scale rock bolt assembly with various angles to analyze the efficiency of the method in real life scenario. The results showed that the new technique improves the performance of the rock bolts by reducing the material wastage, improving environmental performance, facilitating and accelerating the labor works, and finally enhancing the durability of the whole system. Accordingly, this approach provides an efficient alternative for the traditional way of tunnel bolt installation with considerable advantages for the Swedish tunneling industry.
Abstract: In this study the water flow in an open channel over a sharp-crested weir is investigated experimentally. For this reason a series of laboratory experiments were performed in an open channel with a sharp-crested weir. The maximum head expected over the weir, the total upstream water height and the downstream water height of the impact in the constant bed of the open channel were measured. The discharge was measured using a tank put right after the open channel. In addition, the discharge and the upstream velocity were also calculated using already known equations. The main finding is that the relative error percentage for the majority of the experimental measurements is ± 4%, meaning that the calculation of the discharge with a sharp-crested weir gives very good results compared to the numerical results from known equations.
Abstract: Almost all of the domestic refrigerators operate on the principle of the vapor compression refrigeration cycle and removal of heat from the refrigerator cabinets is done via one of the two methods: natural convection or forced convection. In this study, airflow and temperature distributions inside a 375L no-frost type larder cabinet, in which cooling is provided by forced convection, are evaluated both experimentally and numerically. Airflow rate, compressor capacity and temperature distribution in the cooling chamber are known to be some of the most important factors that affect the cooling performance and energy consumption of a refrigerator. The objective of this study is to evaluate the original temperature distribution in the larder cabinet, and investigate for better temperature distribution solutions throughout the refrigerator domain via system optimizations that could provide uniform temperature distribution. The flow visualization and airflow velocity measurements inside the original refrigerator are performed via Stereoscopic Particle Image Velocimetry (SPIV). In addition, airflow and temperature distributions are investigated numerically with Ansys Fluent. In order to study the heat transfer inside the aforementioned refrigerator, forced convection theories covering the following cases are applied: closed rectangular cavity representing heat transfer inside the refrigerating compartment. The cavity volume has been represented with finite volume elements and is solved computationally with appropriate momentum and energy equations (Navier-Stokes equations). The 3D model is analyzed as transient, with k-ε turbulence model and SIMPLE pressure-velocity coupling for turbulent flow situation. The results obtained with the 3D numerical simulations are in quite good agreement with the experimental airflow measurements using the SPIV technique. After Computational Fluid Dynamics (CFD) analysis of the baseline case, the effects of three parameters: compressor capacity, fan rotational speed and type of shelf (glass or wire) are studied on the energy consumption; pull down time, temperature distributions in the cabinet. For each case, energy consumption based on experimental results is calculated. After the analysis, the main effective parameters for temperature distribution inside a cabin and energy consumption based on CFD simulation are determined and simulation results are supplied for Design of Experiments (DOE) as input data for optimization. The best configuration with minimum energy consumption that provides minimum temperature difference between the shelves inside the cabinet is determined.
Abstract: This work provides details on the wind speed behavior within cities of Arraial do Cabo and São Pedro da Aldeia located in the Lakes Region of the State of Rio de Janeiro, Brazil. This region has one of the best potentials for wind power generation. In interurban layer, wind conditions are very complex and depend on physical geography, size and orientation of buildings and constructions around, population density, and land use. In the same context, the fundamental surface parameter that governs the production of flow turbulence in urban canyons is the surface roughness. Such factors can influence the potential for power generation from the wind within the cities. Moreover, the use of wind on a small scale is not fully utilized due to complexity of wind flow measurement inside the cities. It is difficult to accurately predict this type of resource. This study demonstrates how fuzzy logic can facilitate the assessment of the complexity of the wind potential inside the cities. It presents a decision support tool and its ability to deal with inaccurate information using linguistic variables created by the heuristic method. It relies on the already published studies about the variables that influence the wind speed in the urban environment. These variables were turned into the verbal expressions that are used in computer system, which facilitated the establishment of rules for fuzzy inference and integration with an application for smartphones used in the research. In the first part of the study, challenges of the sustainable development which are described are followed by incentive policies to the use of renewable energy in Brazil. The next chapter follows the study area characteristics and the concepts of fuzzy logic. Data were collected in field experiment by using qualitative and quantitative methods for assessment. As a result, a map of the various points is presented within the cities studied with its wind viability evaluated by a system of decision support using the method multivariate classification based on fuzzy logic.
Abstract: Present study was aimed to develop a discharge
measuring device for irrigation and laboratory channels. Experiments
were conducted on sharp edged constricted flow meters having four
types of width constrictions namely 2:1, 1.5:1, 1:1 and 90o in the
direction of flow. These devices were made of MS sheets and
installed separately in a rectangular flume. All these four devices
were tested under free and submerged flow conditions. Eight
different discharges varying from 2 lit/sec to 30 lit/sec were passed
through each device. In total around 500 observations of upstream
and downstream depths were taken in the present work. For each
discharge, free submerged and critical submergence under different
flow conditions were noted and plotted. Once the upstream and
downstream depths of flow over any of the device are known, the
discharge can be easily calculated with the help of the curves
developed for free and submerged flow conditions. The device
having contraction 2:1 is the most efficient one as it allows maximum
critical submergence.
Abstract: This paper outlines the basic installation and operation of magnetic inductive flow velocity sensors on large underground cooling water pipelines. Research on the effects of cathodic protection as well as into other factors that might influence the overall performance of the meter is presented in this paper. The experiments were carried out on an immersion type magnetic meter specially used for flow measurement of cooling water pipeline. An attempt has been made in this paper to outline guidelines that can ensure accurate measurement related to immersion type magnetic meters on underground pipelines.
Abstract: Among modern airflow measurement methods,
Particle Image Velocimetry (PIV) and Particle Tracking Velocimetry
(PTV), as visualized and non-instructive measurement techniques, are
playing more important role. This paper conducts a comparative
experimental study for airflow measurement employing both
techniques with the same condition. Velocity vector fields, velocity
contour fields, voticity profiles and turbulence profiles are selected as
the comparison indexes. The results show that the performance of both
PIV and PTV techniques for airflow measurement is satisfied, but
some differences between the both techniques are existed, it suggests
that selecting the measurement technique should be based on a
comprehensive consideration.
Abstract: In oases, the surface water resources are becoming
increasingly scarce and groundwater resources, which generally have
a poor quality due to the high levels of salinity, are often
overexploited. Water saving have therefore become imperative for
better oases sustainability. If drip irrigation is currently recommended
in Morocco for saving water and valuing, its use in the sub-desert
areas does not keep water safe from high evaporation rates. An
alternative to this system would be the use of subsurface drip
irrigation. This technique is defined as an application of water under
the soil surface through drippers, which deliver water at rates
generally similar to surface drip irrigation. As subsurface drip
irrigation is a recently introduced in Morocco, a better understanding
of the infiltration process around a buried source, in local conditions,
and its impact on plant growth is necessarily required. This study
aims to contribute to improving the water use efficiency by testing
the performance of subsurface irrigation system, especially in areas
where water is a limited source. The objectives of this research are
performance evaluation in arid conditions of the subsurface drip
irrigation system for young date palms compared to the surface drip.
In this context, an experimental test is installed at a farmer’s field in
the area of Erfoud (Errachidia Province, southeastern Morocco),
using the subsurface drip irrigation system in comparison with the
classic drip system for young date palms. Flow measurement to
calculate the uniformity of the application of water was done through
two methods: a flow measurement of drippers above the surface and
another one underground. The latter method has also helped us to
estimate losses through evaporation for both irrigation techniques. In
order to compare the effect of two irrigation modes, plants were
identified for each type of irrigation to monitor certain agronomic
parameters (cumulative numbers of palms and roots development).
Experimentation referred to a distribution uniformity of about 88%;
considered acceptable for subsurface drip irrigation while it is around
80% for the surface drip irrigation. The results also show an increase
in root development and in the number of palm, as well as a
substantial water savings due to lower evaporation losses compared
to the classic drip irrigation.
The results of this study showed that subsurface drip irrigation is
an efficient technique, which allows sustainable irrigation in arid
areas.
Abstract: Mass flow measurement is the basis of most technoeconomic
formulations in the chemical industry. This calls for
reliable and accurate detection of mass flow. Flow measurement
laboratory experiments were conducted using various instruments.
These consisted of orifice plates, various sized rotameters, wet gas
meter and soap bubble meter. This work was aimed at evaluating
appropriate operating conditions and accuracy of the aforementioned
devices. The experimental data collected were compared to
theoretical predictions from Bernoulli’s equation and calibration
curves supplied by the instrument’s manufacturers. The results
obtained showed that rotameters were more reliable for measuring
high and low flow rates; while soap-bubble meters and wet-gas
meters were found to be suitable for measuring low flow rates. The
laboratory procedures and findings of the actual work can assist
engineering students and professionals in conducting their flow
measurement laboratory test work.
Abstract: Newton-Raphson State Estimation method using bus
admittance matrix remains as an efficient and most popular method to
estimate the state variables. Elements of Jacobian matrix are computed
from standard expressions which lack physical significance. In this
paper, elements of the state estimation Jacobian matrix are obtained
considering the power flow measurements in the network elements.
These elements are processed one-by-one and the Jacobian matrix H is
updated suitably in a simple manner. The constructed Jacobian matrix
H is integrated with Weight Least Square method to estimate the state
variables. The suggested procedure is successfully tested on IEEE
standard systems.
Abstract: This paper deals with the experimental investigations
of the in-cylinder tumble flows in an unfired internal combustion
engine with a flat piston at the engine speeds ranging from 400 to
1000 rev/min., and also with the dome and dome-cavity pistons at an
engine speed of 1000 rev/min., using particle image velocimetry.
From the two-dimensional in-cylinder flow measurements, tumble
flow analysis is carried out in the combustion space on a vertical
plane passing through cylinder axis. To analyze the tumble flows,
ensemble average velocity vectors are used and to characterize it,
tumble ratio is estimated. From the results, generally, we have found
that tumble ratio varies mainly with crank angle position. Also, at the
end of compression stroke, average turbulent kinetic energy is more
at higher engine speeds. We have also found that, at 330 crank angle
position, flat piston shows an improvement of about 85 and 23% in
tumble ratio, and about 24 and 2.5% in average turbulent kinetic
energy compared to dome and dome-cavity pistons respectively
Abstract: The sensitivity of orifice plate metering to disturbed
flow (either asymmetric or swirling) is a subject of great concern to
flow meter users and manufacturers. The distortions caused by pipe
fittings and pipe installations upstream of the orifice plate are major
sources of this type of non-standard flows. These distortions can alter
the accuracy of metering to an unacceptable degree. In this work, a
multi-scale object known as metal foam has been used to generate a
predetermined turbulent flow upstream of the orifice plate. The
experimental results showed that the combination of an orifice plate
and metal foam flow conditioner is broadly insensitive to upstream
disturbances. This metal foam demonstrated a good performance in
terms of removing swirl and producing a repeatable flow profile
within a short distance downstream of the device. The results of using
a combination of a metal foam flow conditioner and orifice plate for
non-standard flow conditions including swirling flow and asymmetric
flow show this package can preserve the accuracy of metering up to
the level required in the standards.
Abstract: The Beshar River is one aquatic ecosystem, which is
located next to the city of Yasuj in southern Iran. The Beshar river
has been contaminated by industrial factories such as effluent of
sugar factory, agricultural and other activities in this region such as,
Imam Sajjad hospital, drainage from agricultural farms, Yasuj urban
surface runoff and effluent of wastewater treatment plants ,specially
Yasuj waste water treatment plant. In order to evaluate the effects of
these pollutants on the quality of the Beshar river, five monitoring
stations were selected along its course. The first station is located
upstream of Yasuj near the Dehnow village; stations 2 to 4 are
located east, south and west of city; and the 5th station is located
downstream of Yasuj. Several water quality parameters were
sampled. These include pH, dissolved oxygen, biological oxygen
demand (BOD), temperature, conductivity, turbidity, total dissolved
solids and discharge or flow measurements. Water samples from the
five stations were collected and analyzed to determine the following
physicochemical parameters: EC, pH, T.D.S, T.H, No2, DO, BOD5,
COD during 2008 to 2010. The study shows that the BOD5 value of
station 1 is at a minimum (1.7 ppm) and increases downstream from
stations 2 to 4 to a maximum (11.6 ppm), and then decreases at
station 5. The DO values of station 1 is a maximum (8.45 ppm),
decreases downstream to stations 2 - 4 which are at a minimum (3.1
ppm), before increasing at station 5. The amount of BOD and TDS
are highest at the 4th station and the amount of DO is lowest at this
station, marking the 4th station as more highly polluted than the
other stations .This study shows average amount of the water quality
parameters in first year of sampling (2008) have had a better quality
relation to third year in 2010 because of recent drought in this region
and pollutant increasing .As the Beshar river path after 5th station
goes through the mountain area with more slope and flow velocity
,so the physicochemical parameters improve at the 5th station due to
pollutant degradation and dilution. Finally the point and nonpoint
pollutant sources of Beshar river were determined and compared to
the monitoring results.
Abstract: Microcirculation is essential for the proper supply of
oxygen and nutritive substances to the biological tissue and the
removal of waste products of metabolism. The determination of
blood flow in the capillaries is therefore of great interest to clinicians.
A comparison has been carried out using the developed non-invasive,
non-contact and whole field laser speckle contrast imaging (LSCI)
based technique and as well as a commercially available laser
Doppler blood flowmeter (LDF) to evaluate blood flow at the finger
tip and elbow and is presented here. The LSCI technique gives more
quantitative information on the velocity of blood when compared to
the perfusion values obtained using the LDF. Measurement of blood
flow in capillaries can be of great interest to clinicians in the
diagnosis of vascular diseases of the upper extremities.
Abstract: This analysis investigates the distortion of flow
measurement and the increase of cavitation along orifice
flowmeter. The analysis using the numerical method (CFD)
validated the distortion of flow measurement through the inlet
velocity profile considering the convergence and grid
dependency. Realizable k-e model was selected and y+ was
about 50 in this numerical analysis. This analysis also estimated
the vulnerability of cavitation effect due to inlet velocity profile.
The investigation concludes that inclined inlet velocity profile
could vary the pressure which was measured at pressure tab
near pipe wall and it led to distort the pressure values ranged
from -3.8% to 5.3% near the orifice plate and to make the
increase of cavitation. The investigation recommends that the
fully developed inlet velocity flow is beneficial to accurate flow
measurement in orifice flowmeter.