Synthesis of 2,3-Dioxo-5-(substituted)arylpyrroles and Their 2-Oxo-5-aryl-3-hydrazone Pyrrolidine Derivatives

Some novel2,3-dioxo-5-(substituted)arylpyrroles have been synthesized. Among these, pyrrolidine compound 1b was converted to 2,3-dioxo-5-aryl pyrrolidine 2b. Finally a set of hydrazone derivatives was obtained from the reaction of 2b with various hydrazine salts. The structures of all the new synthesized compounds were confirmed by elemental analyses, IR and 1H-NMR spectra

Statistical modelling for missing and spurious pulses in pulse repetition interval (PRI) analysis

Pulse repetition interval (PRI) analysis based on histogram method is widely used in electronic intelligence (ELINT) systems for emitter recognition. The identification of PRI modulation types using the statistical histogram method has faced inaccurate recognition due to error caused by missing and spurious pulses. In this study, the modelling for the statistical prediction of spurious and missing pulses is done to estimate their distributions density of occurrences that can be related to the robustness of the PRI analysis method. The statistical modelling is simulated using the histogram PRI analysis method and the proposed model is tested for its feasibility using Monte-Carlo simulation. The results obtained show that the proposed model can be used to estimate the presence of missing and spurious pulses, and can be used for testing of the robustness of PRI analysis methods

Comparison of methodologies for signal detection in underwater acoustic noise in shallow tropical waters

Signal detection is important in sonar and underwater digital communication. Optimum signal detection in underwater acoustic noise (UWAN) can be achieved with the knowledge of noise statistics. The assumption of Gaussian noise allows the use of linear correlation (LC) detectors. However, the non-Gaussian nature of UWAN results in the poor performance of such detectors. This study presents an empirical model of the characteristics of UWAN in the shallow waters of an acoustic underwater channel. Four detectors for the detection of known signals in UWAN are compared: locally optimal (LO) detector, sign correlation (SC) detector, LC detector, and the proposed Gaussian noise injection detector (GNID). The performance of the detectors is evaluated according to the detection probability (PD) and receiver operating characteristic curves. Given a probability of false alarm (PFA) rate of 0.01 and PD of 90 percent, the energy-to-noise ratios of the LO detector, SC detector, GIND, and LC detector are 8.854, 10.8, 10, and 12 dB, respectively. Among the four detectors, the LO detector achieves the best performance, whereas the LC detector shows the weakest performance in the presence of non-Gaussian noise

Examining the practice of scaffolding during problem/project based laboratory

Continuous debates on the lack of competency in solving complex engineering problems among engineering graduates in Malaysia have generated numerous researches on inquiry-based learning within the context of engineering education. However, less work had been done to investigate how the Malaysian electrical engineering undergraduates higher order cognitions were facilitated while undergoing project-based or problem-based learning environment. This paper presents a study that examined the practice of scaffolding during Problem/Project Based Laboratory (PBLab) at Digital Signal Processing Laboratory (DSP Lab), Faculty of Electrical Engineering, Universiti Teknologi Malaysia (UTM). A single case study design was employed in which a lecturer cum facilitator and a group of final year undergraduates served as the purposive sampling. In-lab observations that specifically focused on the interactions between the facilitator and the students, as well as a group interview were conducted to generate qualitative data. Drawing on Wood et al.s (1976) functions of scaffolding, as well as Holton and Clarkes (2006) agent of scaffolding, concept-driven thematic analysis was conducted on the two sets of data. The main and constituent themes were uncovered to describe the main function of the facilitators scaffolding and the role of the facilitator in supporting undergraduates cognition while attempting to solve an electronics engineering problem. The findings suggested that the main function of scaffolding during the inlab session was meant for marking critical features, during which the facilitator accentuated the main parts of learning activity that were relevant to the given tasks. In addition, it is also revealed that the facilitator acted as the agent of expert scaffolding while interacting with the students during in-lab sessions. This study provides the insights into the importance of scaffolding as a mechanism for a facilitator who is the expert problem solver to empower the "epistemic selves" (Holton and Clarke, 2006) among the undergraduates who are the novices of complex engineering problems

Effects of temporal frequency towards visual roughness perception by drifted grating stimulation

Previous studies proved that in addition to spatial characteristics function in extracting roughness information, there is potential roughness dependability across changes in the temporal mechanisms of textured surfaces. In the present study, we created temporal coding mechanism by converting fine spatial structure surface into a temporal drifting pattern. We proposed that regular spatial structure of gratings with variation of temporal mechanism have different influence toward roughness perception. Results showed massive individual differences of roughness perception between subjects, suggesting that a combination of spatial and temporal mechanisms accounts for perceptual judgments of roughness. We suggest that visual roughness judgment was determined by spatial in grating stimulation, and improvement is needed in spatial components before temporal coding of visual roughness can be declared