Modeling methods for high-fidelity rotorcraft flight mechanics simulation

The cooperative effort being carried out under the agreements of the United States-Israel Memorandum of Understanding is discussed. Two different models of the AH-64 Apache Helicopter, which may differ in their approach to modeling the main rotor, are presented. The first model, the Blade Element Model for the Apache (BEMAP), was developed at Ames Research Center, and is the only model of the Apache to employ a direct blade element approach to calculating the coupled flap-lag motion of the blades and the rotor force and moment. The second model was developed at the Technion-Israel Institute of Technology and uses an harmonic approach to analyze the rotor. The approach allows two different levels of approximation, ranging from the 'first harmonic' (similar to a tip-path-plane model) to 'complete high harmonics' (comparable to a blade element approach). The development of the two models is outlined and the two are compared using available flight test data

Potensi Serapan Gas Karbondioksida (CO2) Pada Jenis-Jenis Pohon Pelindung Jalan

A Study of Potential Absorption of Carbon Dioxide (CO2) in Wayside Trees in Bogor City around was conductedin April to May 2013 by using a portable LCi ADC Bioscientific Ltd. Photosynthesis System. Inventory of waysidetrees species in the site was done by surveys, and sixty-three samples from twenty-one species of wayside trees havebeen measured. This study for determined the ability of CO2 absorption in each species of wayside trees species.Twenty one species of wayside trees were recorded. Angsana (Pterocarpus indicus), Mahogany (Swieteniamacrophylla), Walnuts (Canarium indicum), and Tanjung (Mimusops elengii) were common wayside trees planted inBogor and surrounding areas. The highest rate of CO2 absorption was recorded for Kersen (Muntingia calabura) onaverage of 23.92 μmol/m2/s , followed by the Bintaro (Cerbera manghas) 16.42 μmol/m2/s, Dadap (Erythrina cristagalli)16.38 μmol/m2/s, and Trembesi (Albizia saman) 15.87 μmol/m2/s. A common planted species in the rangebetween 8 to 13 μmol/m2/s, such as; Angsana (Pterocarpus indicus) 12,79 μmol/m2/s, Walnuts (Canariumindicum) 9,39 μmol/m2/s, Tanjung (Mimusops elengi) 8,72 μmol/m2/s and Mahogany (Swietenia macrophylla) 8,30μmol/m2/s. While the lowest CO2 absorption is Burahol (Stelechocarpus burahol) 7.16 μmol/m2/s, BungaSaputangan (Maniltoa grandiflora) 7.89 μmol/m2/s and Damar (Agathis alba) 7.86 μmol/m2/s. There were positivecorrelation between transpiration rate with CO2 absorption rate and stomatal conductance on all the tree specieswere measured

An Empirical Correction Method for Improving off-Axes Response Prediction in Component Type Flight Mechanics Helicopter Models

Historically, component-type flight mechanics simulation models of helicopters have been unable to satisfactorily predict the roll response to pitch stick input and the pitch response to roll stick input off-axes responses. In the study presented here, simple first-order low-pass filtering of the elemental lift and drag forces was considered as a means of improving the correlation. The method was applied to a blade-element model of the AH-64 APache, and responses of the modified model were compared with flight data in hover and forward flight. Results indicate that significant improvement in the off-axes responses can be achieved in hover. In forward flight, however, the best correlation in the longitudinal and lateral off-axes responses required different values of the filter time constant for each axis. A compromise value was selected and was shown to result in good overall improvement in the off-axes responses. The paper describes both the method and the model used for its implementation, and presents results obtained at hover and in forward flight

Effect of Prewetted Pumice Aggregate Addition on Concrete Properties under Different Curing Conditions

This study researches the effects of different curing conditions on the properties of high strength concrete containing presoaked pumice aggregate (PA). Fine normal weight aggregate is substituted by an equal volume of 1h and 24h presoaked PA at 50% and 100% fractions and a total of five concrete mixtures were prepared. After kept in water, air and hot weather, the performance of concretes were evaluated by determining their physical and mechanical properties at 28 days. Hot weather was found to be the most detrimental condition where the highest strength drops were observed. Frost resistance of concretes was improved with the use of presoaked PA at 50% replacement ratio. The use of presoaked PA also decreased the shrinkage values of concrete specimens. The results showed that the use of presoaked PA in high strength concrete at 50% replacement ratio could contribute to concrete properties when exposed to inadequate curing conditions

Features of Islamic websites, perceptions of Muslim users and utilization behavior: a conceptual model

Islamic websites demand special attention due the nature of the content delivered to the users. To deliver satisfying online knowledge and practice for Muslim Ummah, it is important to identify and evaluate the overall features of Islamic website (Iweb). In this paper, we explore the literature on Islamic website and e-consumer and developed a conceptual model that identifies perceived Muslim user satisfaction. The paper examines three issues namely; features of Iweb user satisfaction, perceived dimensions of this satisfaction judgment, and consequence of Muslim user satisfaction with Iweb