175 research outputs found

    Economic valuation of irrigation water under a major irrigation scheme (Gal Oya) in eastern Sri Lanka

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    The objective of this study was to estimate the economic value of irrigation water used in a crop farm (paddy and chilies) using a Linear Programming approach in the Senanayake Samudra (Gal-Oya Irrigation Scheme) Right Bank System area in the Ampara District.Length: pp.89-94Irrigation schemesIrrigation waterPricingModels

    A User Satisfaction Study of the London Congestion Charging e-Service

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    This research seeks to measure citizen satisfaction with the electronic London Congestion Charging (LCC) payment system offered by Transport For London (TFL) in the United Kingdom (UK). The paper reports on the findings of a survey of 500 users of the TFL LCC online payment system. Satisfaction is measured using the four dimensions from the COBRA framework 0that comprise the cost, opportunity, benefits and risk assessment constructs. The results show that most citizens using the LCC electronic service are satisfied with the service and that the service meets their essential needs. The paper also presents the results of qualitative feedback obtained from the participants that can be used to determine the areas that need further improvement in the current electronic LCC electronic-service (e-service) system and potential influences on user satisfaction

    What is the Brillouin Zone of an Anisotropic Photonic Crystal?

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    The concept of the Brillouin zone (BZ) in relation to a photonic crystal fabricated in an optically anisotropic material is explored both experimentally and theoretically. In experiment, we used femtosecond laser pulses to excite THz polaritons and image their propagation in lithium niobate and lithium tantalate photonic crystal (PhC) slabs. We directly measured the dispersion relation inside PhCs and observed that the lowest bandgap expected to form at the BZ boundary forms inside the BZ in the anisotropic lithium niobate PhC. Our analysis shows that in an anisotropic material the BZ - defined as the Wigner-Seitz cell in the reciprocal lattice - is no longer bounded by Bragg planes and thus does not conform to the original definition of the BZ by Brillouin. We construct an alternative Brillouin zone defined by Bragg planes and show its utility in identifying features of the dispersion bands. We show that for an anisotropic 2D PhC without dispersion, the Bragg plane BZ can be constructed by applying the Wigner-Seitz method to a stretched or compressed reciprocal lattice. We also show that in the presence of the dispersion in the underlying material or in a slab waveguide, the Bragg planes are generally represented by curved surfaces rather than planes. The concept of constructing a BZ with Bragg planes should prove useful in understanding the formation of dispersion bands in anisotropic PhCs and in selectively tailoring their optical properties.Comment: 9 pages, 6 figure

    THz generation using a reflective stair-step echelon

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    We present a novel method for THz generation in lithium niobate using a reflective stair-step echelon structure. The echelon produces a discretely tilted pulse front with less angular dispersion compared to a high groove-density grating. The THz output was characterized using both a 1-lens and 3-lens imaging system to set the tilt angle at room and cryogenic temperatures. Using broadband 800 nm pulses with a pulse energy of 0.95 mJ and a pulse duration of 70 fs (24 nm FWHM bandwidth, 39 fs transform limited width), we produced THz pulses with field strengths as high as 500 kV/cm and pulse energies as high as 3.1 μ\muJ. The highest conversion efficiency we obtained was 0.33%. In addition, we find that the echelon is easily implemented into an experimental setup for quick alignment and optimization.Comment: 19 pages, 4 figure

    A User Satisfaction Study of London's Congestion Charge e-Service: A Citizen Perspective

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    YesThe importance of evaluation and optimization of electronic government (e-government) services is imperative if the government organisations are to have an effective impact on the success and take-up of the services offered. Transport For London's (TFL) London Congestion Charging (LCC) is one of the innovative electronic services (e-services) introduced by the United Kingdom (UK) government to the citizens. While some studies have addressed the impact of the introduction of the congestion charge there has been a dearth of research performed to address user (citizen) satisfaction of the online LCC system. Therefore, this research seeks to measure the citizen satisfaction of using the LCC online payment system offered by TFL. The citizen satisfaction in this context is measured using the four dimensions from the COBRA framework that comprise the cost, opportunity, benefits and risk assessment constructs. This paper presents the findings of a survey of 500 users of the TFL LCC online payment system. It also reports the qualitative feedback obtained from the participants that can be used to determine the areas that need further improvement in the current LCC e-service and potential influences on user satisfaction

    Evidence of sympathetic cooling of Na+ ions by a Na MOT in a hybrid trap

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    A hybrid ion-neutral trap provides an ideal system to study collisional dynamics between ions and neutrals. This system provides a general cooling method that can be applied to optically inaccessible species and can also potentially cool internal degrees of freedom. The long range polarization potentials (Vα/r4V\propto-\alpha/r^4) between ions and neutrals result in large scattering cross sections at cold temperatures, making the hybrid trap a favorable system for efficient sympathetic cooling of ions by collisions with neutral atoms. We present experimental evidence of sympathetic cooling in a hybrid trap of \ce{Na+} ions, which are closed shell and therefore do not have a laser induced atomic transition, by equal mass cold Na atoms in a magneto-optical trap (MOT).Comment: 7 figure

    A case analysis of E-government service delivery through a service chain dimension

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    YesUnlike e-business few studies have examined how information is generated and exchanged between stakeholders in an e-government service chain to generate value for citizens. This case study applies the concept of service chains to empirically explore: a) how internal and external business activities in local government authorities (LGAs) contribute to electronic service delivery, and b) the impact that internal and external stakeholders have on these activities. The case study found that the diversity of stakeholders involved and lack of appropriate mechanisms for information exchange and collaboration are posing the biggest challenges for efficient local egovernment service delivery
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