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Reported are the results of wind-tunnel tests conducted to evaluate aerodynamics characteristics of aircraft in formation flight. A vortex-lattice numerical scheme was used to investigate the effect of spatial offset (horizontal and vertical) between the leading and trailing wings. The wind-tunnel test configurations consisted of echelon, chevron, and in-line formations. Analysis of the data revealed that the spatial offset and the angle of attack of the leading wing had significant impact on the trailing aircraft. For some test conditions an increase in lift-to-drag ratio of the trailing aircraft was measured. Variation in [C.sub.Lmax] and/or [alpha] stall was observed as well. At higher angles of attack of the leading wing, the [C.sub.L]-[alpha] curve of the trailing aircraft was significantly altered.

A novel f-f model is developed constructively which can express any n-dimensional piecewise linear (PWL) function by a superposition of basis functions if it is defined over an nth-order degenerate intersection formed by (n - 1) th-order minimal degenerate intersections. We also propose the concrete functional forms of nth-order basis functions. Being the simplest type of the minimal degenerate intersection, the basis function is the most elementary 'building block' of a PWL function defined in an arbitrary-dimensional space. In addition, the model constitutes a natural continuation to Julian's canonical formulation and can bridge the lattice PWL model and the well-established canonical representation. Index Terms--Basis function, cutting algorithm, lattice PWL model, piecewise-linear (PWL) representation.

An analysis of add/drop filters is presented, using a time-dependent mode-coupling theory. Topics include single-mode resonator, equivalent circuit, and a fourth-order filter.

The binding capacity of wheat bran, rice bran and oat fiber for Ca, Mg, Cu and Zn minerals is stronger in the acid-washing centrifugation (AWC) than in the cold-hot-water-enzyme incubation (WEI). Rice bran and oat fiber are the only fibers which bind more Ca in the WEI method as compared to the AWC method. The protein content and the phytic acid level is higher, and total dietary fiber is lower in the AWC fibers than in the WEI fibers. The WEI method is less effective in stripping minerals than the AWC method.

The three-dimensional bluff-body wake over two-dimensional circular cylinder geometries is investigated. Experiments are conducted wherein five wavy-cylinder models are subjected to wind-tunnel and water-tunnels tests. The laser-light-sheet techniquw is then employed to obtain two-dimensional slices of the wake generated behind the nodes and saddles of the cylinders. Results reveal that the formation of the trailing vortices is narrowest behind the geometric nodes and widest behind the geometric saddles.

A study has been conducted to show that an optical resonator with degenerate symmetric and antisymmetric modes side-coupled to wave-guides performs the same function as a ring resonator. It has been found that for a symmetric system composed of two identical coupled resonators between two waveguides, the expected splitting of the degeneracy can be counteracted with by proper coupling to the waveguides. Finite-difference time-domain simulations of wave propagation through such a filter demonstrates such a concept.

Abstract: In this article, detailed modeling, simulation, and analysis of an isolated wind-hydrogen hybrid energy system is presented. Dynamic nonlinear models of all the major subsystems are developed based on sets of empirical and physical relationships. The performance of the integrated hybrid energy system is then analyzed through digital simulation. Design of dynamic controllers and supervisory control schemes are also presented. Expected behaviors during sudden load variation, wind speed change and hydrogen pressure drop are observed under both stochastic and step-variation conditions. MATLAB-SimulinkTM is employed for dynamic system modeling. This exercise, in essence, outlines a process of wind-hydrogen off-grid system control synthesis and performance evaluation. Finally, results of the analysis are summarized, limitations of the simulation study are identified, and scope for future work is indicated. [Copyright &y& Elsevier]

Abstract: The energy in flowing river streams, tidal currents or other artificial water channels is being considered as viable source of renewable power. Hydrokinetic conversion systems, albeit mostly at its early stage of development, may appear suitable in harnessing energy from such renewable resources. A number of resource quantization and demonstrations have been conducted throughout the world and it is believed that both in-land water resources and offshore ocean energy sector will benefit from this technology. In this paper, starting with a set of basic definitions pertaining to this technology, a review of the existing and upcoming conversion schemes, and their fields of applications are outlined. Based on a comprehensive survey of various hydrokinetic systems reported to date, general trends in system design, duct augmentation, and placement methods are deduced. A detailed assessment of various turbine systems (horizontal and vertical axis), along with their classification and qualitative comparison, is presented. In addition, the progression of technological advancements tracing several decades of R&D efforts are highlighted. [Copyright &y& Elsevier]

Abstract: Spate irrigation is a method of flood water harvesting, practiced in Dera Ismael Khan (D.I. Khan), Pakistan for agricultural production for the last several hundred years in which during monsoon period flood water is used for irrigation before wheat sowing. A field study on the effect of different pre-sowing water application depths on the yield of wheat was conducted during 2006–2007. The spate irrigation command areas normally receive the flood water as a result of rainfall on the mountains during the months of July to September, which also carries a significant amount of sediment load. The flood water flows in different torrents and is diverted through earthen bunds to the fields for irrigation with depth of water application ranging from 21 to 73cm and resulted in sediment deposition of 1.8–3.6cm per irrigation. In this study, the effect on wheat yield of three different pre-sowing water application depths (D1<30cm, D2=30–45cm and D3>45cm) were studied under field conditions. Fifteen fields with field sizes of about 2–3ha were randomly selected, in each field five samples were collected for analysis of soil physical properties, yield and yield components. Five major soil texture classes (silty clay, clay loam, silty clay loam, silt loam and loam) were found in the area with water-holding capacity ranging from 23% to 36.3% (on a volume basis) and bulk density varied from 1.35 to 1.42gcm−3. About 36% more grain yield was obtained from loam soil fields, followed by silt loam (24%) as compared to wheat grown on silty clay soil condition. The maximum wheat grain yield of 3448kgha−1 was obtained from fields with water application depths of 30–45cm and the lowest wheat yield was recorded in fields with water application depths greater than 45cm. On-farm application efficiencies ranged from 22% to 93% with an overall average of about 49%. Due to large and uneven fields, a lot of water is lost. In general, the application efficiency decreased with increasing water application depth. Based on the results of this research, in arid to semi-arid environments, for optimum wheat yield under spate irrigation, the pre-sowing water application depth may be about 30–45cm (September to July) and under or over irrigation should be avoided. [Copyright &y& Elsevier]

In high index contrast integrated optic waveguides, it has been found that waveguide asymmetries can produce cross-polarization coupling. This effect has been well studied for polarization rotation. A similar effect, as produced by fabrication-induced asymmetry, can significantly limit the performance of directional couplers. In this paper, we analyze the effect, propose a method to circumvent these manufacturing-related limitations, and demonstrate an improvement of the extinction ratio from 25 to 40 dB level [ABSTRACT FROM PUBLISHER]

The work presented in this paper was conducted to validate the computer codes such as WIMS-D/4 and CITATION for the criticality analyses of natural uranium fueled, light water cooled, heavy water moderated and graphite reflected reactors such as National Experimental Reactor (NRX) and Canadian Indian Reactor (CIR). These codes are then used to search a proliferation resistant reactor core. It was found that the replacement of light water coolant with heavy water and with increased moderation, the core can be operated at a power level of less than half as compared to the power level of NRX/CIR but the neutron flux will remain unaffected. This core will be smaller in size and therefore there will be savings in required quantities of D2O, graphite and fuel. It will produce much less plutonium with higher concentration of 240Pu, if the burnup is more than 2800 MWD/T. Furthermore, it was found that the void coefficient of the coolant will be less positive and therefore the system will be more safe as compared to original NRX/CIR design. [Copyright &y& Elsevier]

Describes the operation principle of resonant channel add-drop filters based on degenerate symmetric and antisymmetric standing-wave modes. Coupled-mode analysis; Four-port system employing a pair of identical single-mode standing wave resonators; Wavelength division multiplexing; Nuclear simulation of a wave propagation through add-drop filters.

ABSTRACT: The fontal Karachi Coast is widely exposed to human activities which impose ecological and environmental degradation of coastal environment and wetland biodiversity. This study aimed to analyze the changes in coastal belt features including built up land cover, mangroves and vegetation cover, and interrelationship of coastline morphology at frontal Karachi coast. We have utilized the satellite images of Landsat-5 TM and Landsat-8 OLI/TIRS to detect the changes and map coastal features using likelihood supervised classification and unsupervised algorithms(NDBI, NDVI). The spectral data analysis of principal components helped us to discriminate various coastal features by analytical interpretation of images whereas, supervised classification and change detection matrices provided quantitative estimates of variability among the thematic features. We have addressed the spatial changes with explicit references of Karachi Shipyard, Karachi Port, PNS Himalaya, Sandspit, Bundal/Bhundar Island and Far Island Mangrove Forest for the year 2010-2018. It was reckoned that major reduction in "dense mangroves" at Karachi Shipyard from 119.7 to 96.3 hectares and about 100 hectares at Bundal Island(over 2010-18), probably under the influence of the well built-up areas and futile coastal management in current scenario of regional climate changes. [ABSTRACT FROM AUTHOR]