A pre-requisite to reducing the energy intensity of the building sector is to assess and understand current drivers of energy consumption. Drivers include building design characteristics, outdoor environmental conditions, as well as the operation patterns of building systems by occupants. In the United Arab Emirates (UAE), where buildings consume more than 70% of the total electricity demand, a comprehensive analysis of the drivers of building energy performance has not yet been conducted. This paper proposes an approach, which is unique in its ability to capture the combined effects of technical, as well as, operation-related building parameters. A regression models is proposed and applied to data gathered from 713 mixed-use buildings in downtown Abu Dhabi. Results indicate that in addition to physical building parameters such as window tinting, operational parameters, including AC cleanliness, chiller condition, and thermostat temperature setting have shown significant impacts on energy consumption levels.
Globally, biggest amount of water is consumed for agricultural purposes. Part of this consumption is due to the evaporation cooling technique that is typically used in cooling greenhouses. This technique vastly consumes water and energy. Ground Heat-Exchanger is an environmentallyfriendly solution used for heating/cooling and based on seasonal temperature difference between the ground and the ambient. A study was conducted on a ground-to-air heat exchanger used in thermally insulated greenhouse system equipped with actuated windows, LEDs fans, and sensors. A fuzzy controller was proposed to maintain the greenhouse environment by utilizing weather conditions through automated windows and ground heat through the ground heat exchanger. Results showed the heat exchanger can keep the greenhouse temperature at a constant level of about 26?C. It hence can be used for pre-cooling in summer and heating in winter. The proposed controller was able to maintain the greenhouse temperature within the acceptable range.
The connection between energy and water in the UAE is very high: the rely is on desalination to ensure the domestic water demand. Thermal desalination technologies are the major techniques used in the UAE, therefore, cogeneration-based power desalination plants dominate the energy sector in the UAE, which ties the power and the water production together. This bond results in significant impact on the environment and the climate change due to GHG emissions and other solid and liquid waste. The purpose of this paper is to first examine all the existing technologies related to energy generation and desalinated water production, second to investigate the social cost and specify the socio, environmental and economic characteristics of the different present technologies. Third to find out the optimal water and energy production development strategy based on different scenarios.
Existing RC building stock designed before the implementation of current design standards may require efficient seismic retrofit strategies to resist anticipated earthquakes. This study focuses on the effectiveness of RC jacketing, steel jacketing and FRP overlays on improving the seismic performance of low-to-midrise RC frame buildings. Two reference structures representing prestandard RC multi-story buildings are selected for this study based on the current design practices of the region. Detailed inelastic pushover and incremental dynamic analyses are performed using 3D fiber-based numerical models for the assessment of the seismic response of the reference structures before and after retrofit. A parametric study is undertaken to investigate the impact of the jacket thickness and number of FRP layers on improving the seismic performance. It is concluded that both RC and steel jacketing is effective in improving the lateral strengths to meet current design standards, while FRP overlays are efficient in improving ductility.
The Soil-Structure-Interaction (SSI) has a significant effect on the overall structural behavior of reinforced concrete buildings. This research work aims to study the SSI effect for the case of a 6- story building with a pile foundation. The numerical model foresees the study of the main shear wall of the structure with connected reinforced concrete slabs. The foundation system is a pilecap with three piles found within a soil class E, according to ASCE7-10. By using the hexahedral isoparametric finite element, the structure is discretized in 3D, where the adopted concrete material model is the smeared crack approach, and the steel bars are modelled by using embedded rebar elements. Both soil and concrete foundation are discretized with hexahedral elements. Monotonic and cyclic analyses are performed in order to evaluate the behavior of the fixed-base structure and the corresponding SSI model that is founded on the flexible soil.
This paper aims to present an experimental program to investigate the flexural behavior of Fiber- Reinforced concrete (FRC) beams reinforced longitudinally with Basalt Fiber-Reinforced Polymers (BFRP) bars. The experimental program consists of material evaluation and flexure test. Material evaluation was performed in order to obtain the compressive strength of the proposed concrete mix and tensile strength of the internal rebars. Flexure test was conducted on each of the BFRPFRC beams using four-point loading test setup to investigate any enhancements in the flexural behavior in terms of moment capacity, load versus mid-span deflection and crack behavior. The test matrix consists of 6 beams with different comparisons to mainly focus on studying the effect of BFRP reinforcement ratio and fibers type (Basalt and Synthetic).
Evaluating the dynamic characteristics is a fundamental step for the design of buildings when subjected to earthquake loads. One of the essential dynamic properties of structures is the fundamental period. Several expressions for the calculation of the fundamental period have been proposed by building codes and previous studies. However, further assessment studies for the fundamental periods are still needed to provide more reliable formulas for seismic design. In this study, period data for 147 instrumented buildings with various lateral force resisting systems (LFRSs) are compared with different formulas from building codes and previous studies. Another set of period data are considered from selected simulated structures. Different LFRSs are considered, including RC moment resisting frames (MRFs), steel MRFs, RC shear walls, braced systems and masonry structures. The comparisons between the derived period expressions with those of the design provisions confirm the conservative code design approach for the considered systems.
The main purpose of the current research is to implement different Geophysical Techniques (GT) in measuring wave velocity at different soil properties. For this purpose, twenty 6-in-diameter specimens have been prepared with different soil properties for index tests. In addition, two identical 1/3-scale strip footing model tests are constructed and instrumented with geophones, accelerometers, and load cells. The objectives of these large tests are to establish correlations between large and small strain wave velocity on granular materials. These relationships are necessary to predict, from in-situ velocity measurement, the velocity at large deformations required for numerical modeling of various soil materials. Index test results indicate that the Pwave velocity decreases as the soil water content and degree of saturation increases up to certain thresholds, which itself increases with the compaction effort. In addition, the wave velocity becomes larger as the soil includes more fine contents. The clay content affects the soil wave velocity; however, this affect varies with the specimen water content. Results also show that the effect of Portland cement on the soil wave velocity is significant, especially after 3-days curing time. Results of the scaled footing tests indicate that the P-wave velocity increases as the footing applied stress increases, and the largest value was measured directly at the bottom of footing. Finally, a relation that relates stress ratio with velocity ratio for strip footing is proposed for practical implementation.
In this paper, a study is conducted to investigate the use of microwave tomography in the imaging of human proximal legs. In microwave tomography, the human leg is radiated with non-ionizing low-power electromagnetic signals; variations in the dielectric properties of the leg results in changes to the signals measured at receivers in the imaging system. The dielectric properties constitute of the relative permittivity along with the conductivity of the leg tissues. The study herein is carried numerically using a two-dimensional electromagnetic solver implemented using the finite-element method. The human proximal leg geometry is created and meshed using MATLAB and GMSH. The generated mesh is imported to the finite-element solver along with the values of electric properties of various tissues. The simulations show that variations in bone dielectric properties is highly correlated to the variations of the electric fields within the microwave tomography system.
Implantable bioelectrodes have the potential to advance neuroprosthetic therapy tremendously; however, current bioelectrodes have limitations ranging from mechanical mismatch to immunological responses. This paper discusses the preparation of novel, low-cost, flexible bioelectrodes, consisting of silicone polymer and titanium (IV) dioxide, and presents a study of the prepared electrodes' electrochemical and mechanical characteristics. The tested material exhibited ductile properties with samples approaching an elongation of 266?fore rupture, and an elastic modulus of 6.6296 MPa, along with a satisfactory bulk impedance of 93 K?, thus supporting its' capability to be synthesized into implantable electrode.
