排序方式: 共有12条查询结果,搜索用时 782 毫秒
1.
2.
3.
M. F. A. Goosen S. S. Sablani C. Paton J. Perret A. Al-Nuaimi I. Haffar H. Al-Hinai W. H. Shayya 《Solar Energy》2003,75(5):413-419
The long-term aim of our research is to develop humidification–dehumidification desalination technology for farms in arid coastal regions that are suffering from salt-infected soils and shortages of potable groundwater. The specific aim of our current study was to determine the influence of greenhouse-related parameters on a process, called Seawater Greenhouse, which combines fresh water production with growth of crops in a greenhouse system. A thermodynamic model was used based on heat and mass balances. The dimension of the greenhouse had the greatest overall effect on the water production and energy consumption. A wide shallow greenhouse, 200 m wide by 50 m deep gave 125 m3 d−1 of fresh water. This was greater than a factor of two compared to the worst-case scenario with the same area (50 m wide by 200 m deep), which gave 58 m3 d−1. Low power consumption went hand-in-hand with high efficiency. The wide shallow greenhouse consumed 1.16 kW h m−3, while the narrow deep structure consumed 5.02 kW h m−3. Analysis of the local climate indicated that the structure should be built facing the NE direction. We are also in the process of building a commercial size Seawater Greenhouse at a site by the sea. The aim is to demonstrate the technology to local farmers and companies in the Arabian Gulf. The system will allow for the reclamation of salt-infected land by not relying, at all, on groundwater resources. 相似文献
4.
Mustafa K. Taher Al-Nuaimi Wei Hong Xiqi Gao 《Journal of Infrared, Millimeter and Terahertz Waves》2017,38(2):155-165
This article presents the design of non-subwavelength, non-resonant, and non-absorptive dielectric surface that creates a low-level backward diffuse reflections under illumination of a far-field plane wave at millimeter wave regime. Thus, radar cross section reduction of a solid metallic object can be achieved. The dielectric surface is consist of unit cells of only two different electric permittivity (ε r1?=?6.14 and ε r2?=?3.49) distributed across the surface aperture to achieve low-level backscattered diffuse reflections. The unit cells used are having non-subwavelength size (0.53λ80GHz) which ensures an easier fabrication of the presented surface using low cost simple PCB technology, in particular at high frequencies. RCS reduction of more than 10 dBsm is achieved from 70 to 87 GHz (BW?≈?21.65 %) using the presented dielectric surface of optimized permittivity distribution. The RCS reduction capabilities of the presented surface are studied theoretically under both normal and oblique incidences and then fabricated and verified experimentally by reflectivity measurements. 相似文献
5.
Harshal B. Oza Rakesh Pandey Daniel Roper Yusur Al-Nuaimi Marc Goodfellow 《International journal of control》2017,90(8):1664-1677
A new systems model of psoriasis is presented and analysed from the perspective of control theory. Cytokines are treated as actuators to the plant model that govern the cell population under the reasonable assumption that cytokine dynamics are faster than the cell population dynamics. The analysis of various equilibria is undertaken based on singular perturbation theory. Finite-time stability and stabilisation have been studied in various engineering applications where the principal paradigm uses non-Lipschitz functions of the states. A comprehensive study of the finite-time stability properties of the proposed psoriasis dynamics is carried out. It is demonstrated that the dynamics are finite-time convergent to certain equilibrium points rather than asymptotically or exponentially convergent. This feature of finite-time convergence motivates the development of a modified version of the Michaelis–Menten function, frequently used in biology. This framework is used to model cytokines as fast finite-time actuators. 相似文献
6.
Tuning techniques for planar inverted-F antenna 总被引:1,自引:0,他引:1
User terminals of modern mobile communication systems require efficient, low profile antennas, capable of broadband and multi-band operation. In that respect, planar inverted-F antenna (PIFA) designs have emerged that explore the trade-off between the height above the ground-plane and the achievable effective bandwidth. Further possible bandwidth enhancements are studied, as is multi-band operation by switching and tuning the resonant frequency of the PIFA, while maintaining a low height above the ground plane 相似文献
7.
Muhi-Eldeen Z. Ivrissimtzis L.P. Al-Nuaimi M.O. 《Microwaves, Antennas & Propagation, IET》2009,3(2):250-259
Frequency and polarisation reuse for optimum spectral efficiency in local multipoint distribution system (LMDS) networks generate co- and adjacent-channel inter- and intra-cell interference because of the line-of-sight constraints among transmitting and receiving antennas. Such operational constraints limit the system capacity and affect link performance. Measurements at 40 GHz from a number of possible interference scenarios for two different LMDS reuse cellular plans of dual-frequency and dual-polarisation discriminations are presented. An electromagnetic-stochastic propagation model is employed. The model successfully predicts the interference parameters and takes into account the effects of multiple paths and depolarisation caused by reflection and scatter from building surfaces at millimetre-wave frequencies. The probability density function of the signal-to-interference ratio and the statistical channel parameters, such as the average signal strength and the Rician K-factor, are extracted from the measured data and compared with model predictions. 相似文献
8.
Siamarou A. G. Al-Nuaimi M. 《IEEE transactions on instrumentation and measurement》2010,59(3):519-526
9.
The backscatter signal level emerging from vegetation media and its dependence on the azimuthal direction of the receiving antenna are investigated. Experimental results obtained at 11.2 GHz using two different test sites are presented and further characterised in terms of the scattering cross-section per unit area 相似文献
10.
The planning of urban microwave communication systems must consider the harmful interference these systems cause to existing links, and vice versa. Site shielding is an interference reduction technique wherein a building is used deliberately to shield a radio terminal from interfering signal. The site-shielding factor (SSF) is, however, influenced by the arrival of interference on paths caused by reflection and scatter from nearby buildings. Prediction models are needed to estimate the effects arising from the scatter. The paper develops prediction models based on a plane reflector and discusses experimental measurements aimed at the validation of these models. The paper describes the results of the initial stage of a continuing investigation into building scatter aimed at the formulation of a prediction procedure for site shielding suitable for radio system planning and coordination 相似文献