Odd Mathieu Functions Application to Synthesize a Multi-element Radiator Flat-topped Radiation Pattern

The paper studies synthesizing capabilities of a flat-topped radiation pattern when using the expansion of the target radiation pattern into a series in terms of odd Mathieu functions. As parameters for comparing the target and synthesized radiation patterns, we used a main-lobe width at a level of -1 dB and an irregularity of the top of the main-lobe of the radiation pattern. The sector-shaped radiation pattern has been synthesized for linear radiators of various lengths. The convergence of the coefficients of the Mathieu series in the synthesis of the sector-shaped radiation pattern has been estimated. It is shown that the use of piecewise-linear approximation of the target radiation pattern in the synthesis using a series expansion into odd Mathieu functions allows us to improve the quality of the radiation pattern formed.The task that involved finding the amplitude-phase distribution for a linear emitter with a length of 3λ, 4λ and 5λ (λ is operation wavelength) for a target radiation pattern was solved. The target amplitude distribution has the following electrical characteristics: the main-lobe width is 37.5° at a level of -1 dB and the side lobe level (SLL) is -20 dB. The synthesis procedure was performed for two cases. In the first case, the target radiation pattern is represented by a piecewise constant function with a given width. In the second case, the target pattern was specified using piecewise linear approximation of the top and slopes of the main lobe.Comparison of the radiation patterns obtained shows that in the first case, the main-lobe width of the radiation pattern at a level of -1 dB is 34°, the SLL varies from -15.6 to -17 dB, and the irregularity of the main-lobe top of the radiation pattern lies within 0.9 ... 1.2 dB. In the second case, the main-lobe width of the antenna radiation pattern at a level of -1 dB is 36.5°, the SLL is -17.5 dB, and the irregularity of the main-lobe top is 0.4 dB at most. When used, the considered under consideration enables us to obtain both the synthesized patterns for linear radiators of various lengths, and the corresponding amplitude-phase distributions and coefficients of the Mathieu series. An estimate of the convergence of the Mathieu series shows that the use of linear approximation of the target radiation pattern in some cases allows up to 2.7-fold increase in acceleration of the convergence of the Mathieu series. The accuracy of reproducing the sector-shaped pattern by the synthesis method using the expansion into odd Mathieu functions gives good results when synthesizing the amplitude-phase distribution for the linear radiators with an electric length of 5λ or more.

Feasibility of Quantitative Tissue Characterization Using Novel Parameters Extracted From Photoacoustic Power Spectrum Considering Multiple Absorbers

Frequency domain analysis of radio frequency signal is performed to differentiate between different tissue categories in terms of spectral parameters. However, due to complex relationship between the absorber size and spectral parameters, they cannot be used for quantitative tissue characterization. In an earlier study, we showed that using linear relationship between absorber size and two new spectral parameters namely number of lobes and average lobe width, absorber size can be successfully recovered from photoacoustic signal generated by single absorber. As actual biological tissue contains multiple absorbers, in this study we extended the application of these two new spectral parameters for computing absorber size from signals generated by multiple PA absorbers. We revisited our analytical model to establish two new linear relationships between the absorber radius and number of lobes as well as average lobe width considering multiple absorbers with bandlimited acquisition. A simulation study was performed to validate these linear relationships. A retrospective ex vivo study, in which the spectral parameters were computed using multiwavelength photoacoustic signals, was performed with freshly exercised thyroid specimens from 38 actual human patients undergoing thyroidectomy after having a diagnosis of suspected thyroid lesions. From statistical analysis it is shown that both the parameters were significantly different between malignant and non-malignant thyroid and malignant and normal thyroid tissue. Performance of the supervised classification with the computed spectral parameters showed that the extracted parameters could be successfully used to differentiate malignant thyroid tissue from normal thyroid tissue with reasonable degree of accuracy.

Development and Analysis of New NLFM Waveform for Achieving Sidelobe Reduction and Narrowing of Main lobe Width

Aimed at narrowing main lobe width and reduced sidelobe values, we developed three new NLFM chirp waveforms. The ambiguity function and the impact of sampling rate and compression ratios of these waveforms are analyzed. Their performance is examined against the doppler effect and background noise. One of the three designed NLFM chirp waveforms is useful in applications requiring side lobes of -50 dB and narrow main lobe width. The new waveform could achieve reduced sidelobes and narrow main lobe width compared to LFM and other NLFM waveforms

Influence of Cassava Morphological Traits and Environmental Conditions on Field Populations of Bemisia tabaci

High populations of species in the whitefly complex Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) were reported to cause severe damage to cassava in East and Central Africa. However, reasons for B. tabaci population increases are not well understood. We investigated the effect of cassava morphological traits, temperature, rainfall and relative humidity (RH) on the abundance of B. tabaci. Five cassava genotypes with varying levels of resistance to cassava mosaic disease, cassava brown streak disease, and B. tabaci infestation were planted in three Ugandan agro-ecological zones. The experiment was conducted in 2016 and 2017 in a randomized complete block design. Across all locations, the tallest genotype Alado alado supported the lowest number of B. tabaci adults. In areas with high B. tabaci prevalence, leaf area, leaf lobe width, and leaf lobe number exhibited significant positive effects (p < 0.001) on B. tabaci adult count. Positive effects of relative humidity and negative effects of temperature and rainfall on B. tabaci adult and nymph counts were observed in 2016 and 2017, resulting in low populations in Lira. Evidently, temperatures of 28–30 °C, rainfall of 30–150 mm and RH of 55–70%, and deployment of cassava genotypes of low plant height, large leaf area, and lobe width significantly enhanced B. tabaci population growth.

Excitation series design and pulse compression synthesis for high-resolution Lamb wave inspection

Lamb wave pulse compression is a promising technique for ultrasonic nondestructive evaluation and structural health monitoring, in which the excitation waveform is designed to exhibit attractive auto-correlation characteristics including short main-lobe width and small side-lobe amplitude. However, narrowing main-lobe will increase side-lobe amplitude, and vice versa. Conventional time windowing technique is a balance between main-lobe width and side-lobe amplitude. An improvement over time windowing is proposed using pulse compression synthesis method. In this method, a series of excitation waveforms are used to actuate Lamb waves, each response is processed by pulse compression, and all the compression signals are summed together. The excitation series are constructed as linear chirps weighted with different combinations of rectangular and Hanning window functions. The selection of the combination coefficients is optimized to ensure best signal summation. The effectiveness of the proposed method is demonstrated by an experiment, and the robustness to inaccuracy in dispersion compensation is also evaluated. Application of the proposed method for damage detection is demonstrated by a further experiment.

Leaf Area and Its Relationship with Leaf Descriptors Elements in Liquidambar styraciflua L.

This study aimed at determining the leaf area in Liquidambar styraciflua L. and at characterising the relationship between leaf area and leaf descriptors. The biological material was the species Liquidambar styraciflua L. We determined leaf area in 100 leaves (Figure 1) based on the size of median rib (L), leaf width at higher (W1) and lower (W2) lobe level, and on area constants (KA). The size of elements L, W1 and W2 were found by measuring with a precision of ±0.5 mm. Area constants in the species Liquidambar styraciflua L. were KA1 = 0.63, determined depending on leaf width at upper lobe width (W1), and KA2 = 0.81 in relation to the width W2 of the lower lobes. Between the scanned leaf area (SLA) and measured leaf area (MLA) and leaf descriptors (L, W1 and W2) we identified relations of interdependence statistically ensured: r = 0.960 to r = 0.971 for SLA; r = 0.951 to r = 0.981 for MLA W1, and r = 0.933 to r = 0.972 for MLA W2, respectively. Leaf descriptors L, W1 and W2 had a differentiated contribution in determining SLA and MLA. SLA was influenced by leaf length (L) with higher statistic safety (R2 = 0.963, p << 0.001, F = 1277.2) than leaf width at upper lobe width W1 (R2 = 0.943; p<<0.001; F = 797.7) and leaf width at the extremities of the lower lobes W2 (R2= 0.927, p << 0.001, F = 620.59).

Two new species of feather mites (Acarina: Psoroptidia) from the Oriental Magpie-Robin, Copsychus saularis (Passeriformes: Muscicapidae)

Two new feather mite species from the bird host Copsychus saularis (Linnaeus) collected in Indonesia (Kalimantan) are described: Dolichodectes latilobus n. sp. (Proctophyllodidae, Pterodectinae), and Trouessartia saularis n. sp. (Trouessartiidae). The new species, Dolichodectes latilobus, has the following distinctive characters: in males, the opisthosomal lobes are widened in the posterior half; the opisthoventral shields are fused, forming a single shield that covers ventrally the posterior quarter of the body; legs I have longitudinal crest-like processes ; and setae ra on these legs are spiculiform. In females of D. latilobus, the posterior margin of the hysteronotal shield has a deep median invagination, and epimerites II extend to the level of the anterior margin of epigynum. The males of T. saularis have the adanal apodemes with two narrow lateral membranes, and the females have the terminal cleft width smaller than the opisthosomal lobe width, and the collar of the spermatheca cover 1/2 from the length of secondary spermaduct.

Pinna of ear: a potential biometric identifier

Background: Individual differences in morphometric and somatoscopic observations of pinna of ear were studied to explore the potential of pinna of ear as a biometric tool.Methods: Morphometric and somatoscopic data of right ear of 350 Indian individuals (Age: 17-25 years) was collected. Measurements of pinna length, pinna width, pinna root, pinna projection, intertragic distance, ear lobe length, and ear lobe width were taken. Observations were done for presence or absence of Darwin tubercle, flat or rolled helix, and attached or free ear lobe. Probability statistics was extrapolated to assess the variations in ear pinna characters.Results: All measurements showed a wide range. There was statistically significant difference between male and female pinna measurements. The somatoscopic observations showed 82.9% individuals with presence of Darwin tubercle, 99.1% with rolled helix, and 65.4% with free ear lobes. On the basis of extrapolation of ten different morphometric and somatoscopic parameters, the statistics showed the probability of any two individuals having exactly same observations to be 0.0008%.Conclusions: The wide range of measurements in the present study suggested a high possibility of variations amongst the population. If all the parameters including both morphometric and somatoscopic, are taken into consideration, the pinna of ear of each individual is a very distinctive structure, which makes it a potential biometric identifier and with the use of proper technologies, it will be a widely used biometric tool in the future.

Improved Window Function in the Application of MFCC Feature Parameter Extraction

In view of spectrum leakage and the contradictory problem of spectrum accuracy of main lobe and reducing spectrum leakage, MFCC algorithm based on improved window function is proposed. Improved window function is based on the mathematical analysis of Kaiser window, and under the condition of finite sampling points minuses weighted impact function where is at the frequencies that side lobe peaks of correspond to. The amplitude of improved window compared with Kaiser window is smaller, and main lobe width is the same, solving the conflicting problem of main lobe width and side lobe amplitude and reducing spectrum leakage. The experimental results show that speech recognition rate of MFCC feature parameter extraction algorithm based on improved window function is better than Kaiser window and Hamming window.