Gerontological Studies on the Micrometry of Liver of Bakerwali Goat

Background: Goat husbandry has been playing an important role in the economy of our country with special reference to milk, meat, manure and hide production. Bakerwali goat constitutes about 50% of the total goat population of J and K. The liver is an extremely important organ in the body of mammals performing numerous functions. The liver is much heavier in young animals than older animals as it atrophies with age. The present study has been planned to record the micrometrical data about the liver of Bakerwali goat during different age groups. Methods: Liver samples were collected from slaughter houses of Nagrota in and around Jammu city of UT of J and K during 2019-20. The samples were divided into young (below 1 year), adult (2-3 years) and senile (4 years and above) as per the dentition of the goats. Six samples from each age group were collected. The micrometrical observations were recorded on H and E stained sections with the help of an ocular micrometer duly calibrated with stage micrometer. Result: The capsule showed maximum thickness in adults followed by the young and senile age group. The maximum thickness of the capsule was seen at upper part of main lobe (UPOML) in the liver of young and adult whereas, in the senile group, the maximum thickness was seen at middle part of main lobe (MPOML). The diameter of the central vein showed the highest values in adults, followed by young and senile probably due to increased liver functions in adult. The mean values of length of hepatocytes ranged between 13.50 to 22.50 µm in all regions of the liver of irrespective of age groups. The mean values showed higher values in adult and senile age groups. The nuclear diameter of the hepatocytes ranged between 9.00 to 13.50 µm with mean values varying between 9.72±0.58 to 10.05±0.50 µm in all the three age groups. The maximum number of portal triads per field was seen at ventral part of main lobe (VPOML) in the senile group whereas the minimum number was observed at MPOML in the young group. In general, several portal triads per field were highest in the senile group followed by adult and young.

Synthesis of low sidelobe level antenna arrays through only main lobe assumption

An analytic method is proposed to design uniformly spaced arrays so that have as low as possible sidelobe level and having directivity as close as to that of uniformly excited arrays. The ideal array factor of arrays is assumed to have only one main lobe. The actual synthesized array would have sidelobe levels which can be controlled by a parameter. Some examples are given to verify the effectiveness of the presented method.

Air and Metal Vias Combined Metamaterial-Based Lens for Radiation Performance Enhancement of Short-Pulse Tapered Slot Antenna

A post-wall-structured tapered slot antenna (PWTSA) loaded with an embedded metamaterial-based lens (metalens) is proposed and investigated for short-pulse applications. The proposed embedded metalens consists of not only a metallic delay lens, but also an airy acceleration region surrounding the lens, which is different from the conventional metalenses used in various tapered slot antennas and can exhibit a small equivalent permittivity. Therefore, the embedded metalens has a large usable range of permittivity and does not increase the size of the original prototype PWTSA. The post-wall structure and metalens of the proposed antenna can help it achieve a comprehensive and balanced performance, including a high fidelity, low cross-polarization, stable main-lobe direction and gain enhancement. The simulated and measured results show that without any increase in antenna size, the proposed antenna enhances the realized gain by 6.4 dB over the frequency range from 9 to 26 GHz and achieves a stable radiation with the offset of the main-lobe direction being confined to 2° up to 24.9 GHz. Furthermore, the cross-polarization levels are less than −20 dB and the fidelity is kept high for the short-pulse radiation with the frequency spectrum up to 30 GHz.

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.

Robust Antijamming Strategy Design for Frequency-Agile Radar against Main Lobe Jamming

To combat main lobe jamming, preventive measures can be applied to radar in advance based on the concept of active antagonism, and efficient antijamming strategies can be designed through reinforcement learning. However, uncertainties in the radar and the jammer, which will result in a mismatch between the test and training environments, are not considered. Therefore, a robust antijamming strategy design method is proposed in this paper, in which frequency-agile radar and a main lobe jammer are considered. This problem is first formulated under the framework of Wasserstein robust reinforcement learning. Then, the method of imitation learning-based jamming strategy parameterization is presented to express the given jamming strategy mathematically. To reduce the number of parameters that require optimization, a perturbation method inspired by NoisyNet is also proposed. Finally, robust antijamming strategies are designed by incorporating jamming strategy parameterization and jamming strategy perturbation into Wasserstein robust reinforcement learning. The simulation results show that the robust antijamming strategy leads to improved radar performance compared with the nonrobust antijamming strategy when uncertainties exist in the radar and the jammer.

Non-linear beamformer with long short-term memory network

Acoustic beamforming with a microphone array enables spatial filtering in a wide frequency range. It is a challenging issue to sharpen the main-lobe in the lower frequency region with a small-scale microphone array, of which the number and spacing of microphones are small. A neural network-based non-linear beamformer achieves a breakthrough in sharpening the main-lobe. The non-linear beamforming works well for the narrowband signals but is weak in wideband beamforming. The non-linear beamforming with the long short-term memory is proposed to deal with wideband speech signals. The long short-term memory network is trained in the recurrent neural network architecture with the sequence of audio data such as speech signals. The performance of the proposed beamformer is confirmed using a small-scale 8-ch MEMS microphone array, where eight microphones are linearly arranged with the neighboring spacing of 10 mm, under a real environment. The beam-pattern of the proposed non-linear beamformer succeeds in sharpening the main-lobe although the linear delay-and-sum beamformer could not achieve frequency selectivity. The feasibility of the proposed beamformer is also confirmed in speech enhancement.