The focus of present research endeavor was to design a robust fractional-order proportional-integral-derivative (FOPID) controller with specified phase margin (PM) and gain cross over frequency (${\omega }_{gc}$) through the reduced-order model for continuous interval systems. Currently, this investigation is two-fold: In the first part, a modified Routh approximation technique along with the matching Markov parameters (MPs) and time moments (TMs) are utilized to derive a stable reduced-order continuous interval plant (ROCIP) for a stable high-order continuous interval plant (HOCIP). Whereas in the second part, the FOPID controller is designed for ROCIP by considering PM and ${\omega }_{gc}$ as the performance criteria. The FOPID controller parameters are tuned based on the frequency domain specifications using an advanced sine-cosine algorithm (SCA). SCA algorithm is used due to being simple in implementation and effective in performance. The proposed SCA-based FOPID controller is found to be robust and efficient. Thus, the designed FOPID controller is applied to HOCIP. The proposed controller design technique is elaborated by considering a single-input-single-output (SISO) test case. Validity and efficacy of the proposed technique is established based on the simulation results obtained. In addition, the designed FOPID controller retains the desired PM and ${\omega }_{gc}$ when implemented on HOCIP. Further, the results proved the eminence of the proposed technique by showing that the designed controller is working effectively for ROCIP and HOCIP.

Engineering systems are modeled as interval systems recently. In this paper, an improved technique for model reduction of high-order continuous interval systems is presented using Anderson corollary and Routh approximation. The distinguishing features of the proposed method are: (i) it ensures exact matching of responses of reduced-order interval model and high-order interval system at steady-state; (ii) it retains interval-value of steady-state of high-order interval system; and (iii) it produces interval model for interval system. Firstly, the denominator of the reduced-order model is obtained based on Routh table. Then, the numerator is obtained by matching the interval-values of steady-state of high-order interval system and reduced-order interval model. A single-input-single-output (SISO) test system is considered to explain the efficiency of the proposed method. The step responses of SISO test systems are obtained and presented for comparative study. From the results, it is observed that the proposed method provides better approximants.

This article develops an analytic hierarchy process (AHP)-assisted model-reduction approach for a higher-order airport-centric microgrid (ACM). The full-order ACM model is approximated by a computationally simpler lower-order transfer function while retaining its essential steady-state and transient characteristics. The model approximation helps in analysis and controller design. For the same, a multi-objective fitness function is formulated from selected time moments and Markov parameters of the original and reduced models. AHP is used to determine the relative importance of the individual matching objectives through pairwise comparisons and normalized priority weights. The resulting weighted optimization problem is solved using the brown-bear optimization algorithm (BBOA) to estimate coefficients of the reduced model. During optimization, exact matching of steady-state gain is imposed to eliminate steady-state mismatch, while Hurwitz stability conditions ensure that the reduced model remains stable. Effectiveness of the proposed approach is evaluated using step and impulse responses, frequency-domain characteristics, time-domain specifications, and integral error indices. The results show that the AHP–BBOA-based reduced model closely reproduces the dominant dynamics of the higher-order ACM while offering a compact representation suitable for controller design, simulation, and real-time frequency-response studies.

Objective: Nifurtimox is a type of nitrofuran derivative employed for treating sleeping sickness as well as Chagas disease. The aim is to develop and validate a precise and specific liquid chromatography mass spectrometric technique for the estimation of Nifurtimox in human plasma.Material and Method: Chromatographic separation had been accomplished on reverse-phase C18 (4.6 mm × 100 mm, 3.5 µm) column employing benznidazole as an internal standard along mobile phase made up of methanol and 5 mM aqueous ammonium acetate in a 75:25 (v/v) ratio at a flow rate of 0.8 ml/min in isocratic mode. A quadrupole mass spectrometer running in positive mode and with numerous reaction monitoring settings was employed to quantify the procedure.Result and Discussion: The developed analytical method exhibited good recovery and was validated over a calibration range of 0.5–400 ng/ml. In the ESI spectra, the major ion peaks for Nifurtimox and the internal standard, benznidazole, were observed at m/z 288 and m/z 261, respectively, corresponding to their [M+H]+ ions. The method exhibited LOD, LOQ, and LLOQ of 0.2 ng/ml, 1.0 ng/mL and 0.5 ng/ml respectively. Precision at intra and interday and accuracy were evaluated at low (1 ng/ml), medium (50 ng/ml), and high (400 ng/ml) quality control levels, showing a %RSD below 2. The percentage recoveries exceeded 95%, with %RSD values under 2. Overall, the validated method is suitable for routine quantification of Nifurtimox in biological samples.