| 1. |
- Al-Ansari, Nadhir
(författare)
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Management of water resources in Iraq : perspectives and prognoses
- 2013
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Ingår i: Engineering. - : Scientific Research Publishing, Inc.. - 1947-3931 .- 1947-394X. ; 5:6, s. 667-684
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Tidskriftsartikel (refereegranskat)abstract
- Iraq is one of the Middle East and North African countries (MENA region). The country is currently facing a serious water shortage problem. This problem is expected to be more severe in the future where the supply is predicted to be 43 and 17.61 Billion Cubic Meters (BCM) in 2015 and 2025 respectively while current demand is estimated to be between 66.8 and 77 BCM. It has been estimated that the Tigris and Euphrates river discharges will continue to decrease with time, and they will be completely dry by 2040. Serious, prudent and quick measures need to be taken to overcome this problem. The government should take measures to have a strategic water management vision, including regional coop-eration and coordination, research and development, improving agriculture and sanitation sector as well as public awareness program. These measures are required in order to address the following topics: Strategic Water Management Vision, Regional cooperation and coordination, Irrigation and Agriculture, Water Supply and Sanitation, and Research and Development.
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| 2. |
- Al-Rawabdeh, Abdulla M., et al.
(författare)
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A GIS-based drastic model for assessing aquifer vulnerability in Amman-Zerqa groundwater basin, Jordan
- 2013
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Ingår i: Engineering. - : Scientific Research Publishing, Inc.. - 1947-3931 .- 1947-394X. ; :5, s. 490-504
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Tidskriftsartikel (refereegranskat)abstract
- Amman-Zerqa Basin (AZB) is a major basin in Jordan. The concentration of economic, agricultural and social activities within the basin makes it of prime importance to Jordan. Intensive agricultural practices are widespread and located close to groundwater wells, which pose imminent threats to these resources. Groundwater contamination is of particular concern as groundwater resources are the principal source of water for irrigation, drinking and industrial activities. A DRASTIC model integrated with, and GIS tool has been used to evaluate the groundwater vulnerability of AZB. The Drastic index map showed that only 1.2% of the basin’s total area of 3792 km2 lies in the no vulnerable zone and about 69% is classified as having low pollution potential. The results also revealed that about 30% of the catchment area is moderately susceptible to pollution potential and slightly 1% is potentially under high pollution risk. These results suggest that almost one third of the AZB is at moderate risk of pollution potential. These areas are mainly in the north-east and central parts of the basin where the physical factors like gentle slope and high water table well support the chances of getting shallow aquifer water polluted. Areas with high vulnerable pollution are mainly the central of Amman old city.
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| 3. |
- Bernardo, Ricardo, et al.
(författare)
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Measurements of the Electrical Incidence Angle Modifiers of an Asymmetrical Photovoltaic/Thermal Compound Parabolic Concentrating-Collector
- 2013
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Ingår i: Engineering. - : Scientific Research Publishing, Inc.. - 1947-3931 .- 1947-394X. ; 5, s. 37-43
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Tidskriftsartikel (refereegranskat)abstract
- Reflector edges, sharp acceptance angles and by-pass diodes introduce large variations in the electrical performance of asymmetrical concentrating photovoltaic/thermal modules over a short incidence angle interval. It is therefore important to quantify these impacts precisely. The impact on the electrical performance of the optical properties of an asymmet-rical photovoltaic/thermal CPC-collector was measured in Maputo, Mozambique. The measurements were carried out with the focus on attaining a high resolution incidence angle modifier in both the longitudinal and transversal directions, since large variations were expected over small angle intervals. A detailed analysis of the contribution of the diffuse radiation to the total output was also carried out. The solar cells have an electrical efficiency of 18% while the maxi-mum measured electrical efficiency of the collector was 13.9 % per active glazed area and 20.9 % per active cell area, at 25 °C. Such data make it possible to quantify not only the electrical performance for different climatic and operating conditions but also to determine potential improvements to the collector design. The electrical output can be increased by a number of different measures, e.g. removing the outermost cells, turning the edge cells 90°, dividing each receiver side into three or four parts and directing the tracking, when used, along a north-south axis.
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| 4. |
- Gomes, João, et al.
(författare)
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Testing bifacial PV cells in symmetric and asymmetric concentrating CPC collectors
- 2013
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Ingår i: Engineering. - : Scientific Research Publishing, Inc.. - 1947-3931 .- 1947-394X. ; 5, s. 185-190
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Tidskriftsartikel (refereegranskat)abstract
- Bifacial PV cells have the capacity to produce solar electricity from both sides and, thus, amongst other advantages, allow a significantly increase both in peak and annual power output while utilizing the same amount of silicone. Ac-cording to the manufacturer, the bifacial cells are around 1.3 times more expensive than the single-sided cells. This way, bifacial PV cells can effectively reduce the cost of solar power for certain applications.Today, the most common application for these cells is in stationary vertical collectors which are exposed to sunlight from both sides, as the relative position of the sun changes throughout the day. Another possible application is to utilize these cells in concentrating collectors. Three test prototypes utilizing bifacial PV cells were built. The initial two proto-types were built for indoor testing and differed only in geometry of the reflector, one being asymmetric and the other symmetric. Both prototypes were evaluated in an indoor solar simulator. Both reflector designs yielded positive electri-cal performance results and similar efficiencies from both sides of the cell were achieved. However, lower fill factor than expected was achieved for both designs when compared to the single cell tests. The results are discussed and sug-gestions for further testing are presented. A third prototype was built in order to perform outdoor evaluations. This pro-totype utilized a bifacial PV cells string laminated in silicone enclosed between 2 standard glass panes and a collector box with an asymmetric CPC concentrator. The prototype peak electrical efficiency and temperature dependence were evaluated. A comparison between the performance of the bottom and top sides of the asymmetric collector is also pre-sented. Additionally, the incidence modifier angle (IAM) is also briefly discussed.
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| 5. |
- Hamid Muhammed, Hamed, et al.
(författare)
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Using Ultrasonic Spectrometry to Estimate the Stability of a Dental Implant Phantom
- 2013
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Ingår i: Engineering. - 1947-3931 .- 1947-394X. ; 5, s. 570-574
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Tidskriftsartikel (refereegranskat)abstract
- A challenging problem in dental implant surgery is to evaluate the stability of the implant. In this simulation study, an experimental phantom is used to represent a jawbone with a dental implant. It is made of a little pool filled with soft-tissue equivalent material and a disc of fresh Oakwood with a metal screw. Varying levels of contact between screw and wood are simulated by screwing in or out the screw. Initially, the screw is screwed in and fixed firmly in wood. Thereafter, the screw is screwed out, a half turn each time, to increase the gap gradually between wood and screw. Pulse-echo ultrasound is used and the power spectra of the received echo-signals are computed. These spectra are normalized then analyzed by using the partial least squares method to estimate the corresponding implant stiffness grade in terms of number of turns when beginning from the initial tight-screw state then screwing out the screw. A coefficient of determination R2 of 96.4% and a mean absolute error of ±0.23 turns are achieved when comparing real and estimated values of stiffness grades, indicating the efficiency of this approach.
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| 6. |
- Hatem, Mohammed, et al.
(författare)
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Proportioning of cement-based grout for sealing fractured rock-use of packing models
- 2013
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Ingår i: Engineering. - : Scientific Research Publishing, Inc.. - 1947-3931 .- 1947-394X. ; 5:10, s. 765-774
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Tidskriftsartikel (refereegranskat)abstract
- Fractured, very permeable rock hosting repositories for radioactive waste will require grouting. New grout types of possible use where long-term performance is needed should have a small amount of cement for minimizing the increase in porosity that will follow from the ultimate dissolution and erosion of this component. They have to be low-viscous and gain strength early after injection and packing theory can assist designers in selecting suitable proportions of various grout components. Optimum particle packing means that the porosity is at minimum and that the amount of cement paste needed to fill the voids between aggregate particles is very small. Low porosity and microstructural stability must be guaranteed for long periods of time. Organic additives for reaching high fluidity cannot be used since they can give off colloids that carry released radionuclides and talc can be an alternative superplasticizer. Low-pH cement reacts with talc to give high strength with time while Portland cement gives early but limited strengthening. The clay mineral palygorskite can be used for early gelation because of its thixotropic properties. Once forced into the rock fractures or channels in soil it stiffens and serves as a filter that prevents fine particles to migrate through it be lost. However, its hydrophilic potential is too high to give the grout a high density and high strength. According to the experiments carried out most of the investigated grouts are injectable in fractures with apertures down to 100 μm.
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| 7. |
- Issa, Issa E., et al.
(författare)
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Sedimentation processes and useful life of Mosul dam Reservoir, Iraq
- 2013
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Ingår i: Engineering. - : Scientific Research Publishing, Inc.. - 1947-3931 .- 1947-394X. ; 5:10, s. 779-784
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Tidskriftsartikel (refereegranskat)abstract
- The sedimentation process is the most important problems that affect directly the performance of reservoirs due to the reduction of the storage capacity and possible problems effecting the operation. Thus periodic assessment of the storage capacity and determining sediment deposition patterns is an important issue for operation and management of the reservoirs. In this study, bathymetric survey results and an analytical approach had been used to assess the characteristics of sedimentation and estimate the useful life of Mosul Reservoir. It is located on the Tigris River in the north of Iraq. The water surface area of its reservoir is 380 km2 with a designed storage capacity of 11.11 km3 at a maximum operating level (330 m a.s.l). The dam started operating in 1986. No detailed study was yet carried out to assess its reservoir. The present study indicated that the annual reduction rate in the dead and live storage capacities of the reservoir is 0.786% and 0.276% respectively. The observed results (bathymetric survey) and algebraic formula show approximately that the useful life of Mosul dam reservoir is about 125 years. Furthermore, the stage-storage capacity curves for the future periods (prediction curves) were established using bathymetric survey data.
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| 8. |
- Koch, Christian, 1958, et al.
(författare)
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”Integrated Design Process” a concept for Green Energy Engineering
- 2013
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Ingår i: Engineering. - : Scientific Research Publishing, Inc.. - 1947-3931 .- 1947-394X. ; 5:3, s. 292-298
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Tidskriftsartikel (refereegranskat)abstract
- Consulting Engineers and Architects are currently experimenting with the concept of “Integrated Design Process” (IDP). This paper views Integrated Design Process as a process tool and a concept for management and organization of the green energy engineering process. Moreover such a concept is understood both as systematic knowledge and a symbolic device for enabling change. The paper briefly review international variants, and focus on two variants present in Den-mark: an architect and engineering variant of IDP. The differences between the concepts include different roles for main actors, the use of information technology, the relation to lean, and forms of collaboration. The paper discusses two building projects focusing on teams of engineers and architects in the early conceptual phase. One develops a solution focused on energy saving technologies, the other on energy producing. It is argued that in this practical context, IDP is viewed as ambiguous and not well defined, and the architects and engineer work hard understanding and using the con-cepts even when directly involved. It is difficult to reach consensus on how to do it. The various players agree that an increased interdisciplinary interaction in the design team is necessary in order to comply with the increased complexity of green energy building design. IDP shows potential as a driver for green energy engineering and technologies, as tra-ditional roles and responsibilities in the design process is changed, and sustainable solutions for green buildings can reach a higher standard and quality and are integrated earlier in the design process.
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| 9. |
- Oliva, Marc Vila, et al.
(författare)
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New Approach for Limited-Angle Problems in Electron Microscope Based on Compressed Sensing
- 2013
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Ingår i: Engineering. - 1947-3931 .- 1947-394X. ; 5:10B, s. 575-578
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Tidskriftsartikel (refereegranskat)abstract
- New advances within the recently rediscovered field of Compressed Sensing (CS) have opened for a great variety of new possibilities in the field of image reconstruction and more specifically in medical image reconstruction. In this work, a new approach using a CS-based algorithm is proposed and used in order to solve limited-angle problems (LAPs), like the ones that typically occur in computed tomography or electron microscope. This approach is based on a variant of the Robbins-Monro stochastic approximation procedure, developed by Egaziarian, using regularization by a spatially adaptive filter. This proposal consists on filling the gaps of missing or unobserved data with random noise and enabling a spatially adaptive denoising filter to regularize the data and reveal the underlying topology. This method was tested on different 3D transmission electron microscope datasets that presented different missing data artifacts (e.g, wedge or cone shape). The test results show a great potential for solving LAPs using the proposed technique.
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| 10. |
- Pusch, Roland, et al.
(författare)
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A talc-based cement-poor concrete for sealing boreholes in rock
- 2013
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Ingår i: Engineering. - : Scientific Research Publishing, Inc.. - 1947-3931 .- 1947-394X. ; 5:3, s. 251-267
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Tidskriftsartikel (refereegranskat)abstract
- Deep investigation boreholes in crystalline rock for site selection of repositories for high-level radioactive waste are proposed to be sealed by installing a series of dense concrete and clay plugs. These should prevent radionuclides from leaking canisters at depth to migrate to the biosphere through the holes. The concrete seals will be installed where the holes intersect water-bearing fracture zones to serve as stable and low-permeable supports for adjacent clay plugs. Low porosity and microstructural stability must be guaranteed for many thousands of years and ordinary Portland cement with organic superplastizer will not fulfil the requirements since the high pH will cause degradation of contacting clay and the organic additive can produce colloids with a capacity to carry radionuclides up to the biosphere. Very cement-poor concrete (<8 %) based on low-pH cement and with talc as plasticizer is an option but it matures more slowly, which requires that the construction of seals is made so that sufficient bearing capacity for carrying overlying clay seals is reached.
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