High-performance and highly stable 0.3-nm-full-width-at-half-maximum interference optical filters

Fabrication of very-narrow-bandpass optical tunable filters [(0.3 nm full width at half-maximum) (FWHM)] is reported. To improve the film densities, the O(2) ion-assisted deposition-method is used in the fabrication. In the succession of high- and low-refractive-index layers, the commonly used TiO(2) material is replaced by Ta(2)O(5), which suits the ion-assisted fabrication technique. The relative thicknesses of the filter multilayer structure of 1/2/1 are modified to 0.998/2.007/0.998, which reduces the shift difference in the central wavelengths with regard to the p and s polarizations when the filter is tilted. These improvements enabled fabrication of 0.3-nm-FWHM optical tunable filters with improved stability characteristics.     

Dynamic characteristics of optical intersecting-waveguidemodulators/switches with curved electrodes

The dynamic behavior of optical modulators/switches in the form of intersecting waveguides with curved electrodes is formulated. It is shown that the electrode curvature is very effective in achieving reflected pulses in good resemblance to the incident ones. Further, the speed of operation is found to be high and is shown to depend upon the commonly known capacitance of the device and the time required for refractive index variations to settle down; and also upon the relative pulsewidths of the optical and modulating signals and the extent of their synchronization. The intersection angle is found to influence the propagation delays of the spatial components, which are equalized by properly chosen structural parameters, to achieve unbroadened and undistorted output pulses. The flexibility in the bandwidth of even a fabricated device, through adjustment of the driving conditions, is demonstrated and the capability of such devices to handle a very wide range of optical pulsewidths is clarified     

Chirp-improvement of optical intersecting-waveguideswitch/modulators by electrode curvature

Introduction of slight exponential curvature into the electrode shape of optical intersecting-waveguide switch/modulators is proposed as the means of improving their frequency-chirping behavior. The improvement is achieved by adjusting the electrode curvature to make it pose a constant angle of incidence to all plane-wave spatial components of the guided mode. This results in reduction of the phase disturbances associated with the total reflection process and the frequency-chirping is, consequently, lowered     

A-Eye: Automating the role of the third umpire in the game of cricket

Cricket is a sport that involves two teams, say Team A and Team B, and two field umpires. Initially, Team A bats to score some runs, while Team B balls. Then, Team A balls and Team B bats to overcome the score of Team A. If this happens, then Team B wins. Otherwise, Team A wins. The balling team can dismiss a batsman from scoring through a Run-Out, i.e., the batsman fails to enter an area before three stumps are dislodged in that area. In this case, a third umpire makes the ‘Run-Out/Not-Out’ decision through video technology. This process can consume around one minute which disrupts the pace of the game. In this paper, we propose and validate a novel technology called A-Eye, which automates the role of the third umpire. By applying A-Eye to a set of autonomously-filmed Run-Out videos, we show that it is efficient as compared to the third umpire, and almost as accurate. Also, it can be used to estimate a rating for the field umpires. These results have been recognized internationally, and have convinced our local cricket council to employ A-Eye within a professional cricket tournament.     

Predicting scientific impact based on <Emphasis Type="Italic">h</Emphasis>-index

Predicting the future impact of a scientist/researcher is a critical task. The objective of this work is to evaluate different h-index prediction models for the field of Computer Science. Different combinations of parameters have been identified to build the model and applied on a large data set taken from Arnetminer comprised of almost 1.8 million authors and 2.1 million publications’ record of Computer Science. Machine learning prediction technique, regression, is used to find the best set of parameters suitable for h-index prediction for the scientists from all career ages, without enforcing any constraint on their current h-index values with R ² as a metric to measure the accuracy. Further, these parameters are evaluated for different career ages and different thresholds for h-index values. Prediction results for 1 year are really good, having R ² 0.93 but for 5 years R ² declines to 0.82 on average. Hence inferred that prediction of h-index is difficult for longer periods. Predictions for the researchers having 1 year experience are not precise, having R ² 0.60 for 1 year and 0.33 for 5 years. Considering scientists of different career ages, average R ² values for researchers having 20–36 years of experience were 0.99. For the researches having different h-index values, researchers having low h-index were difficult to predict. Parameters set comprising of current h-index, average citations per paper, number of coauthors, years since publishing first article, number of publications, number of impact factor publications, and number of publications in distinct journals performed better than all other combinations.     

Extinction ratios and scattering losses of opticalintersecting-waveguide switches with curved electrodes

Optical intersecting-waveguide switches with curved electrodes are analyzed. It is shown that the electrode-curvature in the form of a logarithmic spiral results in reflected field distributions in good resemblance to the incident one with reduced transverse shifts. Large extinction ratios and low scattering losses with small voltage-length product are, therefore, achievable. It is concluded that electrode curvature in the form of a logarithmic spiral is effective in realization of low insertion loss, high extinction ratios and small size optical switches     

Renewable hot dry rock geothermal energy source and its potential in Pakistan

Geothermal energy source, one of the viable renewable energy sources, has encouraging potential to generate full base-load electricity, which has not been explored so far in Pakistan. Though the country can be benefited by harnessing the hydro-geothermal options of energy generation in areas where sources exist, but most of these sources lie in extreme remote and inaccessible rugged mountainous ranges away from the urban-industrial centers. On the other hand, the present study shows that the HDR geothermal option is one of the most viable renewable sources considering the tectonic setup of Pakistan. Results of the study highlight the HDR geothermal energy prospects at relatively deeper depths than hydro-geothermal resources in water-free condition. The basement tectonic analyses reveal that the HDR prospects could be found even just below the urban-industrial centers of Pakistan where there are no hot springs and/or geysers like southern Indus basin in Sindh province or the Kharan trough in the western Balochistan province. Presence of high earth-skin temperature gradient trends derived from satellite temperature data and the high geothermal gradient anomalous zone derived from scanty data of bottom-hole temperatures of some of the oil and gas exploratory wells, indicates encouraging prospects for HDR energy sources in southern Indus and Thar Desert regions inclusive of Karachi synclinorium area. These high geothermal gradients have been inferred to be the result of the deep-seated southern Indus and the Thar fossil-rift structures. Moreover, the prospects of the HDR geothermal energy sources have also been inferred in the Chagai Arc region and the Kharan–Panjgur tectonic depression in the western part of Pakistan based on the analysis of integrated geophysical data. If HDR prospects are developed, they can offer the sustainable, CO₂-free and independent of time, of day, of weather or season, and the base-load energy-generation resource.     

Review of geothermal energy resources in Pakistan

Pakistan, despite the enormous potential of its energy resources, remains energy deficient and has to rely heavily on imports of hydrocarbon products to satisfy hardly its needs. Moreover, a very large part of the rural areas does not have the electrification facilities because they are either too remote and/or too expensive to connect to the national grid. Pakistan has wide spectrum of high potential renewable energy sources, conventional and as well non-conventional. Many of them have not been adequately explored, exploited and developed. Geothermal energy is one of them. Pakistan can be benefited by harnessing the geothermal option of energy generation as substitute energy in areas where sources exist. Most of the high enthalpy geothermal resources of the world are within the seismic belts associated with zones of crustal weakness like the seismo-tectonic belt that passes through Pakistan having inherited a long geological history of geotectonic events. The present study of the geotectonic framework suggests that Pakistan should not be lacking in commercially exploitable sources of geothermal energy. This view is further strengthened by (a) the fairly extensive development of alteration zones and fumeroles in many regions of Pakistan, (b) the presence of a fairly large number of hot springs in different parts of the country, and (c) the indications of Quaternary volcanism associated with the Chagai arc extending into Iran and Afghanistan border areas. These manifestations of geothermal energy are found within three geotectonic or geothermal environments, i.e., (i) geo-pressurized systems related to basin subsidence, (ii) seismo-tectonic or suture-related systems, and (iii) systems related to Neogene–Quaternary volcanism. A few localities, scattered sporadically all over the country, have been studied to evaluate only some of the basic characteristic parameters of the geothermal prospects. The present review study the geothermal activities of varying intensity and nature, associated with different geotectonic domains, and reveals the viable potential of the geothermal environments, which could be exploited for the generation of sustainable indigenous energy in Pakistan.     

Optical intersecting-waveguide switches with widened angle ofdeflection

Reflection type optical switches with intersecting waveguides and bow-tie electrodes are proposed. The intersection angles of these switches are widened because of the implementation of the bow tie electrodes. The guided incident mode is expanded into an infinite spectrum of plane waves. Snell's law is applied to calculate the reflection and refraction coefficients. It is analytically shown that the intersection angle can be almost doubled without remarkable adverse effects upon the extinction ratios and scattering loss. It is, therefore, anticipated that optical switches with bow-tie electrodes exhibit superior characteristics over those with straight ones     

Low-loss optical waveguide-bend configuration with curved corner reflector

A new bend configuration with curved corner reflector in the form of a logarithmic spiral is proposed. It is shown that this structure has a small size and very low bend loss for a large bending angle and small refractive index difference at the reflector interface.<>