Scientia Iranica
Volume:30 Issue: 4, Jul-Aug 2023

DNA computing is a new kind of computation for solving the complex problems with the huge degree of parallelism. Recently it is found that DNA-based logic systems can be useful in many of biomedical applications such as early cancer detection. As an example, DNA logic systems have been utilized successfully to detect the risky patterns of nucleotide-based cancer biomarkers (microRNAs). In this paper, an automatic design flow is proposed to facilitate the design, verification and physical implementation of multi-stage and large-scale DNA logic circuits. Digital Microfluidic Biochips (DMFB) have been used recently as a promising platform for efficient implementation of DNA-based computing systems and circuits. We used this technology as the physical platform for implementation of DNA-based circuits.Our experiments and implementations show the feasibility, accuracy, efficiency and simplicity of the proposed design flow. Final DNA reactions that are synthesized by the proposed design flow are verified and simulated with stochastic DNA-reaction simulators to prove the correctness of the proposed design flow. This design flow can open a new horizon for researchers and scientists to design, implement and evaluate the DNA-based logic systems.

This paper establishes a centralized model to activate residential demand response in order to improve distribution network reliability. The model aims at minimizing the damage cost imposed by load curtailments following occurrence of unexpected events. In this model, distribution system operator (DSO) and responsive customers have already signed a contract authorizing the DSO alters the operation of responsive appliances whenever system reliability is jeopardized. The model addresses consumers’ preferences and guarantees that the operation of appliances is displaced within the bounds defined by the owners. Once an unexpected event occurs, the DSO commits responsive appliances to avoid likely violations in the network operational limits and costly load curtailments. The proposed model is mathematically formulated in the form of mixed integer linear programming (MILP) and its capability is depicted via applying to a real-world distribution network with some residential consumers. The comparison of service reliability indices after and before utilizing demand response potentials illustrates the effectiveness of the model.

This article presents a design method of miniaturized, circularly polarized (CP), concentric ring-shaped monopole on-chip antenna for 24 GHz short-range application. The proposed antenna covers automotive radar spectrum 22-29 GHz with a resonance at 24 GHz. Taking a simple circular ring-shaped patch as reference antenna, a small gap is introduced in the closed-loop structure that helps to provide the required travelling wave current distribution for realizing the CP property. Then a smaller circular ring is incorporated inside the reference antenna to improve the antenna performance in terms of CP characteristics. Finally, the proposed antenna is tuned to obtain the CP characteristics in the desired band ranging from 23.2 GHz to 27 GHz with 3-dB axial ratio (AR) bandwidth of 3.8 GHz. It offers a maximum gain of -4.5 dBi and wide angular range coverage (HPBW>75° in both E and H-plane). The standard CMOS process with only one level of mask (metal patterning) is used to realize the designed antenna. Compact in size of 3.8 mm × 4 mm × 0.678 mm, simple design layout, and its performance make the antenna as a suitable candidate for system-on-chip (SoC) application.

Nowadays, with the increase of population, demand for efficient public transportation systems has increased. Magnetic levitation (maglev) trains are one of the best choices for the future. There are three separated systems in a classical magnetic train to achieve desirable performance. Hence, several control systems and sensors are essential for train operation. Accordingly, the classical maglev trains include complex structures, and they are so expensive. This paper presents the design, optimization, and control of a combined magnetic train structure with the integrated performance of suspension and guidance and a complementary propulsion system. These combined topologies provide a simple design, more convenient movement, and reduce construction and operation costs.

High gains with highly efficient circularly polarized (CP) microstrip planar and conformal cylindrical patch antenna are designed for ISM band. Dumbbell shaped slot is incorporated at the centre of an irregular hexagonal radiator for the production of circular polarisation with high gain. The simulated results indicate impedance mismatch loss (S11) bandwidth of 78.8 MHz and an axial ratio bandwidth (AR) of 10.3 MHz for planar patch. However the impedance mismatch loss bandwidth and AR bandwidth comes out to be 46.2 MHz and 10.6 MHz for conformal cylindrical patch antenna respectively which shows that return loss bandwidth is dropped down by almost 42% for the case of conformal cylindrical antenna and axial ratio bandwidth remains almost similar. Axial Ratio beam-width for Phi = 0 degree are 83 degree and 61 degree for planar patch and conformal patch respectively. Consequently, the gain obtained in planar patch is 8.79 dBic with the efficiency of 96.33% and in the case of conformal patch, the gain comes out to be 4.16 dBic with an efficiency of 95 %.

Reverse power (RP) phenomenon in synchronous generators may lead to severe damage to the generator prime mover due to motoring action of the generator. The operation of the usual technique, which detects RP on the basis of current direction, is too slow because of utilization of intentional time delay in the relay structure. The deliberate time delay helps the relay to avoid tripping during unwanted disturbances. This paper proposes a novel angular-based scheme to detect RP in synchronous generators. For this, the proposed technique uses the load angle (δ) and the phase difference between voltage and current (θ), as the angular quantities of the generator. Furthermore, other electrical parameters of the generator such as current and voltage are also utilized as the supplementary parameters for RP detection. Ultimately, this contribution uses the analysis of vertical component of E_A (E_A Sinδ) and also the tangential component of I_A on V (I_A Cosθ) in the generator phasor diagram for making the final decision. To verify the performance of the angular-based technique, extensive simulations are carried out on two sample systems (single machine and three machines infinite bus), under different conditions and the final results show the satisfactory performance of the proposed algorithm.

In this paper, an analytical model is proposed for evaluating electromagnetic performances of permanent magnet vernier machines (PMVMs) under healthy and faulty conditions. The proposed model employs flexible magnetic equivalent circuit (MEC) method, which its accuracy can be selected by tunable parameters. The model is capable of considering the influence of saturation effect, skewed slots, slot leakage fluxes, and various winding arrangements for the machines with desired properties. First, the proposed model is used to predict the no-load performance of machine at healthy condition. Then, the machine loading behaviors under healthy and demagnetization fault conditions are analyzed by the MEC model. Moreover, the results of the proposed model are compared and validated with those of 2-D finite element method (FEM) and 3-D FEM. Eventually, a specific pattern is extracted from the stator current spectrum to detect the demagnetization fault.

Among various storage technologies used for the energy storage systems, the supercapacitors, the Pb-acid-Batteries (PABs) and the lithium-Batteries (LBs) are widely used for microgrid applications. The supercapacitors with high-power density are suitable for fast power regulations; conversely, the PABs have high-energy density, which makes them suitable for long-term energy management. Since the PABs and the supercapacitor can complement each other deficiencies, their combination as a hybrid energy storage system is used. However, the LB has both high-energy and high-power densities. Therefore, an LB Energy Storage System (LBESS) can similarly function like a Pb-acid battery-supercapacitor-hybrid-ESS (PSHESS). This paper tends to determine which one is technically and economically more suitable for applications in islanded microgrids. For this purpose, a frequency control and energy management scheme is proposed. It maintains the balance between demand and supply, and also keeps the microgrid frequency within safe operational limits using the least needed sizes for the energy storage systems. Simulation results reveal the costs of LIBESS and PSHESS would be $140325.93 and $209408.37, respectively, which shows that the cost of the PSHESS is $69082.44 or almost 49.2 % more than the cost of the LIBESS. This indicates that the LBESS is more cost-effective than the PSHESS.