853 research outputs found

    Tools and Techniques for testing of Flight Critical Software

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    Flight control system software is a critical component of the digital flight control computer of light combat aircraft. The problems associated with the testing of flight critical software and the test tools, and techniques used to achieve maintainability, and structural and functional coverage of test cases are presented. Also, the experience gained throughout the cycle of testing-design and implementation, reviews and revisions, test execution and software error detection and modificaton of test cases based on requirements and design changes, and regression testing are enumerated. It presents an object-oriented approach towards testing to make it less tedious, more creative, reviewable and easily miantainable

    Performance Evaluation of Different DS-CDMA Receivers Using Chaotic Sequences

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    Direct sequence-code division multiple access (DS-CDMA) technique is used in cellular systems where users in the cell are separated from each other with their unique spreading codes. In recent times DS-CDMA has been used extensively. These systems suffers from multiple access interference (MAI) due to other users transmitting in the cell, channel inter symbol interference (ISI) due to multipath nature of channels in presence of additive white Gaussian noise(AWGN). Spreading codes play an important role in multiple access capacity of DS-CDMA system. M-sequences, gold sequences etc., has been traditionally used as spreading codes in DS-CDMA. These sequences are generated by shift registers and periodic in nature. So these sequences are less in number and also limits the security. This thesis presents an investigation on use of new type of sequences called chaotic sequences for DS-CDMA system. These sequences are generated by chaotic maps. First of all, chaotic sequences are easy to generate and store. Only a few parameters and functions are needed even for very long sequences. In addition, an enormous number of different sequences can be generated simply by changing its initial condition. . Chaotic sequences are deterministic, reproducible, uncorrelated and random-like, which can be very helpful in enhancing the security of transmission in communication. This Thesis investigates the performance of chaotic sequences in DS-CDMA communication systems using various receiver techniques. Extensive simulation studies demonstrate the performance of the different linear and nonlinear DS-CDMA receivers like RAKE receiver, matched filter (MF) receiver, minimum mean square error (MMSE) receiver and Volterra receiver using chaotic sequences and the performance have been compared with gold sequences

    ANN and RSM based Modeling of Moringa Stenopetala Seed Oil Extraction: Process Optimization and Oil Characterization

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    Moringa Stenopetala is a plant species that is endemic to the southern region of Ethiopia. It is primarily cultivated for its nutritional value and is considered an important food source. The present research aimed to analyse the physicochemical properties of Moringa Stenopetala seed oil (MSO) obtained through solvent extraction method utilising hexane as the solvent. The collection of seeds was conducted in Adama, which is situated in the East Shawa zone of Oromia, Ethiopia. Prior to the extraction procedure, the seeds' average moisture content, crude ash, fibre, protein, and oil content were analysed and found to be 6.27%, 7.8%, 2.7%, 26.5%, and 43.2%, respectively. Using the Response Surface Method (RSM) and Artificial Neural Network (ANN), the extraction process was modeled. The study utilised numerical solutions to determine the optimal process parameters for maximising oil yield during extraction. The results indicated that a particle size of 0.85mm, a temperature of 85°C, and an extraction time of 4.75 hours were the most effective parameters. Furthermore, an investigation was conducted on the physical and chemical properties of the oil obtained under optimised conditions

    Novel Characterization Method of Biodiesel Produced from Soybean Oil using Thermogravimetric Analysis

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    The aim of this study was to demonstrate thermogravimetric analysis (TGA) as a potential method for monitoring biodiesel production. Soybean oil and commercial biodiesel were mixed in different proportions by weight. Mixtures of different biodiesel/soybean oil ratios were also created by interrupting a base-catalyzed transesterification process for producing biodiesel at various times. The mixtures produced by both approaches were analyzed with TGA. The results were then compared with data obtained by proton nuclear magnetic resonance spectroscopy ( 1HNMR spectroscopy). The relative weight losses in both sets of mixtures we generated correlated well to the proportion of biodiesel present in the sample. The results from both analytical methods were in good agreement and within a deviation of 5%. Thus, TGA is a simple, convenient and economical method for monitoring biodiesel production

    東アジア共通農業政策の提案 : 自給率・関税率・財政負担・環境負荷

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    An efficient Pd-catalyzed domino reaction of α,α-dialkyl-(2- bromoaryl)methanols to 6,6-dialkyl-6H-benzo[c]chromenes is presented. Their formation can be explained via a five membered Pd(II)-cycle that efficiently involves a domino homocoupling with the second molecule, β-carbon cleavage, and finally intramolecular Buchwald-Hartwig cyclization. This domino process effectively involves breaking of five σ-bonds (2C-Br, 2O-H, and a C-C) and formation of two new σ-bonds (C-C and C-O). This mechanistic pathway is unprecedented and further illustrates the power of transition metal catalysi

    Palladium-mediated highly regio- and stereoselective intermolecular β-arylation on allylic alcohols: Synthesis of functionalized allylic alcohols

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    An efficient and highly regio- and stereoselctive Pd-catalyzed β-arylation method for the formation of β-aryl allylic alcohols, employing aryl iodides, 1-bromo-2-iodobenzenes, and 2-bromobezaldehydes as coupling partners, is presented. The β-aryl allylic alcohols formed in this Pd-catalyzed transformation is unexpected under conventional Jeffery conditions without the assistance of silver salt. It is proposed that the reaction is substrate controlled, and the selective formation of the product depends on the size or nature of the substituent at the ortho position on the aromatic ring of the allylic alcohol par

    Synthesis of substituted isoxazoles and 1,3,4-oxadiazoles

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    An efficient intermolecular [Pd]-catalyzed C–C and intramolecular [Cu]-catalyzed C–O bonds formation: synthesis of functionalized flavans and benzoxepine

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    An efficient three-step strategy for the synthesis of functionalized flavans, starting from readily available 2-bromoiodobenzenes and aryl vinyl alcohols, is presented and successfully extended to benzoxepine. An intermolecular [Pd]-catalyzed C–C and an intramolecular [Cu]-catalyzed C–O bond formations have been employed as key transformations of the strategy

    Cloud vertical structure over a tropical station obtained using long-term high-resolution radiosonde measurements

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    Cloud vertical structure, including top and base altitudes, thickness of cloud layers, and the vertical distribution of multilayer clouds, affects large-scale atmosphere circulation by altering gradients in the total diabatic heating and cooling and latent heat release. In this study, long-term (11 years) observations of high-vertical-resolution radiosondes are used to obtain the cloud vertical structure over a tropical station at Gadanki (13.5°&thinsp;N, 79.2°&thinsp;E), India. The detected cloud layers are verified with independent observations using cloud particle sensor (CPS) sonde launched from the same station. High-level clouds account for 69.05&thinsp;%, 58.49&thinsp;%, 55.5&thinsp;%, and 58.6&thinsp;% of all clouds during the pre-monsoon, monsoon, post-monsoon, and winter seasons, respectively. The average cloud base (cloud top) altitudes for low-level, middle-level, high-level, and deep convective clouds are 1.74&thinsp;km (3.16&thinsp;km), 3.59&thinsp;km (5.55&thinsp;km), 8.79&thinsp;km (10.49&thinsp;km), and 1.22&thinsp;km (11.45&thinsp;km), respectively. Single-layer, two-layer, and three-layer clouds account for 40.80&thinsp;%, 30.71&thinsp;%, and 19.68&thinsp;% of all cloud configurations, respectively. Multilayer clouds occurred more frequently during the monsoon with 34.58&thinsp;%. Maximum cloud top altitude and cloud thickness occurred during the monsoon season for single-layer clouds and the uppermost layer of multiple-layer cloud configurations. In multilayer cloud configurations, diurnal variations in the thickness of upper-layer clouds are larger than those of lower-layer clouds. Heating and cooling in the troposphere and lower stratosphere due to these cloud layers are also investigated and peak cooling (peak warming) is found below (above) the cold-point tropopause (CPT) altitude. The magnitude of cooling (warming) increases from single-layer to four- or more-layer cloud occurrence. Further, the vertical structure of clouds is also studied with respect to the arrival date of the Indian summer monsoon over Gadanki.</p
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