Accurate forecasts of tourism demand are prerequisites in the decision making process in many organizations in the private and public sectors. Any information concerning the future evolution of tourism flows is of gre...
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Accurate forecasts of tourism demand are prerequisites in the decision making process in many organizations in the private and public sectors. Any information concerning the future evolution of tourism flows is of great importance to hoteliers, tour operators and other industries concerned with tourism, services or transportation. In the last few decades international tourism demand has attracted substantial academic interest, resulting in a wide range of successful forecasting approaches. Much attention has been paid to econometric models that use regression techniques to estimate the underlying relationship between tourism demand and its determinants;unfortunately, empirical studies suggest that these models usually fail to outperform simple time series models. The current study focuses on an alternative approach, the Tourism Technical Analysis System (TTAS), incorporating the use of technical analysis techniques and building on the similarities between stock and tourism markets. The absolute and directional accuracy of TTAS is evaluated in relation to a range of time series and econometric methods for forecasting international tourism demand, using as a benchmark well-known published research.
In determining the correct operation of relays of a protection scheme, proper representation of instrument transformers and their behavior in conditions where there can be transient is very critical. This paper presen...
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In determining the correct operation of relays of a protection scheme, proper representation of instrument transformers and their behavior in conditions where there can be transient is very critical. This paper presents a simulation model for assessing the transient performance of capacitive voltage transformers (CVTs). In order to test the validity of the developed model, four CVT operational conditions are considered using field data collected from one of the Nigerian electric utility 330/132/33 kV substations. The model simulation results revealed various configuration performance responses that could affect relay protection schemes to different degrees. As expected, the CVT responses showed that faults initiated at zero voltage crossing, which is the worst transient condition, produced transient voltage magnitude up to 40% of the nominal voltage while faults initiated at the crest produced minimum transient voltage magnitude. It is shown that the model developed for the selected instrument transformer yielded satisfactory results
We present a resonant cantilever sensor for use in chemical and biological sensing applications. Electrostatically actuated suspended indium phosphide (InP) waveguides are used as the sensing cantilevers. This sensor ...
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ISBN:
(纸本)1424402778
We present a resonant cantilever sensor for use in chemical and biological sensing applications. Electrostatically actuated suspended indium phosphide (InP) waveguides are used as the sensing cantilevers. This sensor uses an integrated optical detection scheme which eliminates the need for free space optical components seen in traditional systems. Discussions on device design as well as data collection methods are presented. Mass sensitivity in the range of Deltam = 6.6times10 -15 g is reported, comparable to similar cantilever sensor designs. Integration of waveguide cantilever sensors with on chip optical sources and detectors is also discussed
We report a new on-chip method for actuating an optical fiber in 2-axes. Opposing comb-drive actuators with integrated 3-D wedges (fabricated using gray-scale technology [ 1, 2]) create a translatable, variable height...
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We report a new on-chip method for actuating an optical fiber in 2-axes. Opposing comb-drive actuators with integrated 3-D wedges (fabricated using gray-scale technology [ 1, 2]) create a translatable, variable height v-groove to alter the horizontal and vertical alignment of an optical fiber cantilever. Such an actuator is attractive for on-chip active alignment of fiber optics to edge-coupled optoelectronic devices. The design and fabrication of this variable height actuator is conducive to batch fabrication since all structural components are fabricated in silicon using a single lithography and dry-etching step. Actuation of a cleaved fiber tip > 20 µ m in each direction is demonstrated.
Fuel cell stacks produce a DC output with a 2:1 variation in output voltage from no load to full load. A power conditioner consisting of DC-DC and DC-AC converters is required for utility interface. The DC-DC and DC-A...
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Fuel cell stacks produce a DC output with a 2:1 variation in output voltage from no load to full load. A power conditioner consisting of DC-DC and DC-AC converters is required for utility interface. The DC-DC and DC-AC stages are operated in high frequency employing PWM control for voltage and current regulation. The switch mode nature of the power converter generates common mode voltage with respect to ground. The presence of high frequency common mode voltage with respect to ground contributes to circulating ground current which can interfere with ground fault protection system and also contribute to neutral shift and electro magnetic interference (EMI). This paper presents an analysis of common mode voltage in fuel cell powered converters connected to electric utility and discusses several mitigation methods. Several possible fuel cell power converter topologies are considered for utility scale generation.
The problem of delayed reward in reinforcement learning is usually tackled by implementing the mechanism of eligibility traces. In this paper we introduce an extension of eligibility traces to solve one of the challen...
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The problem of delayed reward in reinforcement learning is usually tackled by implementing the mechanism of eligibility traces. In this paper we introduce an extension of eligibility traces to solve one of the challenging problems in reinforcement learning. The concept of opposition traces is proposed in this work to deal with large state space problems in reinforcement learning applications. We combine the idea of opposition and eligibility traces to construct the opposition-based Q(lambda). The results are compared with the conventional Watkins' Q(lambda) and reflect a remarkable performance increase.
Robust tuning of lead-lag type controller used for regulating FACTS control signal to improve dynamic stability has been an area of interest in research. This paper presents a new approach based on the foraging behavi...
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Robust tuning of lead-lag type controller used for regulating FACTS control signal to improve dynamic stability has been an area of interest in research. This paper presents a new approach based on the foraging behavior of *** Bacteria in the human intestine, to optimize simultaneously three constants each of four lead-lag type UPFC controller present in a single machine infinite bus (SMIB) power system. For the tuning purpose, a multi-objective cost function is formulated that accounts for damping factors and ratios of various system modes for a wide range of operating conditions. Robustness of the proposed tuning method is shown by transient stability analysis of the system time domain simulations when subjected to disturbances at different operating conditions.
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