Exploring the energy landscape of a SAM-I riboswitch

SAM-I riboswitches regulate gene expression through transcription termination upon binding a S-adenosyl-L-methionine (SAM) ligand. In previous work, we characterized the conformational energy landscape of the full-length Bacillus subtilis yitJ SAM-I riboswitch as a function of Mg2+ and SAM ligand concentrations. Here, we have extended this work with measurements on a structurally similar ligand, S-adenosyl-l-homocysteine (SAH), which has, however, a much lower binding affinity. Using single-molecule Förster resonance energy transfer (smFRET) microscopy and hidden Markov modeling (HMM) analysis, we identified major conformations and determined their fractional populations and dynamics. At high Mg2+ concentration, FRET analysis yielded four distinct conformations, which we assigned to two terminator and two antiterminator states. In the same solvent, but with SAM added at saturating concentrations, four states persisted, although their populations, lifetimes and interconversion dynamics changed. In the presence of SAH instead of SAM, HMM revealed again four well-populated states and, in addition, a weakly populated ‘hub’ state that appears to mediate conformational transitions between three of the other states. Our data show pronounced and specific effects of the SAM and SAH ligands on the RNA conformational energy landscape. Interestingly, both SAM and SAH shifted the fractional populations toward terminator folds, but only gradually, so the effect cannot explain the switching action. Instead, we propose that the noticeably accelerated dynamics of interconversion between terminator and antiterminator states upon SAM binding may be essential for control of transcription.

A Three-Phase Model Predictive Approach for Smooth Line-Switching in Islanded Microgrids

This paper deals with a new line-switching method that facilitates the network reconfiguration of islanded microgrids. Its distinct features include the ability to handle network asymmetries and the minimization of the line current during the switching action. This is attained by developing a sensitive-based three-phase model predictive method to determine the operating set-points of the distributed generators (DGs) that minimize the current of the candidate line participating in the switching action. These set-points correspond to the positive-sequence powers as well as the negative- and zero-sequence currents of all DGs. Furthermore, the network constraints such as voltage limits and power limits of DGs are always satisfied. Simulations are performed in a balanced 33-bus islanded network as well as in the unbalanced IEEE 8500-node network to evaluate the performance of the proposed method.

A Three-Phase Model Predictive Approach for Smooth Line-Switching in Islanded Microgrids

This paper deals with a new line-switching method that facilitates the network reconfiguration of islanded microgrids. Its distinct features include the ability to handle network asymmetries and the minimization of the line current during the switching action. This is attained by developing a sensitive-based three-phase model predictive method to determine the operating set-points of the distributed generators (DGs) that minimize the current of the candidate line participating in the switching action. These set-points correspond to the positive-sequence powers as well as the negative- and zero-sequence currents of all DGs. Furthermore, the network constraints such as voltage limits and power limits of DGs are always satisfied. Simulations are performed in a balanced 33-bus islanded network as well as in the unbalanced IEEE 8500-node network to evaluate the performance of the proposed method.

ELECTRONIC FUSE USING RESETTABLE POLY FUSE FOR OVER CURRENT PROTECTION

This paper presents a new technique to deal with the high load currents or fluctuating currents using poly fuse as its major component. Poly fuse is a resettable fuse which goes on increasing its resistance, blocking the excess current until the current is back to normal. Once the current is under normal conditions, the resistance stabilizes and the path between supply and load is reconnected. The proposed work also uses a reed relay which breaks the path exactly at the specified rating, allowing a fast switch. The combination of poly fuse and reed relay provides more efficient outputs as compared to traditional circuit breakers. The fast-switching action, accurate results and the smaller size makes poly fuse more suitable for most of the power devices.

Switching Action of a Bistable Fluidic Amplifier for Ultrasonic Testing

Air-coupled ultrasonic testing is widely used in the industry for the non-destructive testing of compound materials. It provides a fast and efficient way to inspect large concrete civil infrastructures for damage that might lead to catastrophic failure. Due to the large penetration depths required for concrete structures, the use of traditional piezoelectric transducer requires high power electric systems. In this study, a novel fluidic transducer based on a bistable fluidic amplifier is investigated. Previous experiments have shown that the switching action of the device produces a high-power broadband ultrasonic signal. This study will provide further insight into the switching behaviour of the fluidic switch. Therefore, parametric CFD simulations based on compressible supersonic RANS simulations were performed, varying the inlet pressure and velocity profiles for the control flow. Switching times are analyzed with different methods, and it was found that these are mostly independent of the slope of the velocity profile at the control port. Furthermore, it was found that an inversely proportional relationship exists between flow velocity in the throat and the switching time. The results agree with the theoretical background established by experimental studies that can be found in the literature.

Application of Perovskite Layer to Rotor for Enhanced Stator-Rotor Capacitance for PMSM Shaft Voltage Reduction

Adjustable speed drives use Pulse Width Modulation (PWM) to switch DC-bus voltage for the synthesis of three-phase voltages to provide power to the permanent magnet synchronous motor (PMSM). This switching action produces very short rise and fall times and Common Mode Voltage (CMV) in the motor winding, exciting the parasitic capacitances inherent to the motor geometry. These parasitic capacitances give rise to shaft voltage due to a voltage divider action. Therefore, in this paper, first, motor parasitic capacitances and voltage divider action is explained. Second, the Barium Titanate (BTO) layer is coated onto the rotor to enhance stator-to-rotor compound capacitance and a simulation is performed showing the dependence of the shaft voltage on the permittivity of the perovskite (BTO) layer. The rotor BTO layer reduces the bearing voltage ratio as well. Third, experimental results are presented showing effectiveness of the application of the BTO layer to rotor and reduction of shaft voltage of the motor in anticipation to mitigate the damaging electric discharge machining (EDM) bearing currents. Likewise, the experiment shows that the magnetic design of the motor is not affected by the BTO layer to rotor.

A dynamic cruise control system (DCCS) for effective navigation system

With the fast development of artificial intelligence, robotics, and embedded system along with sensor technologies, the speed control mechanism is required in various other applications such as automatic or self-piloting aircraft, auto-driven vehicles, auto driven lifts and much other robotics based automation plants, etc. For each unpredictable and progressed vehicular framework accompanies a better route that is fit for utilizing the two GPS and INS related sign. There have been a noteworthy number of research works being completed towards creating sliding mode control framework. In case of inaccurate navigational data or no availability of navigational service, the cruise control could also stop working. Hence, there is a need to evolve up with a novel system offering reliable and fault tolerant navigation system in order to minimize the dependencies on GPS-based information and maximize the utilization of INS based information. This manuscript presents a dynamic cruise control system to achieve better navigation under uncertainties. The performance of the system is analyzed by incorporating sliding mode and fuzzy logic and achieves better accuracy in tracking error, computational complexity (28 sec of simulation time) under chattering and switching action operation.

Single-Switching Reachable Operation Points in a DC-DC Buck Converter: An Approximation from Time Optimal Control

In this paper, we study the time optimal control problem in a DC-DC buck converter in the underdamped oscillatory regime. In particular, we derive analytic expressions for the admissible regions in the state space, satisfying the condition that every point within the region is reachable in optimal time with a single switching action. We then make use of the general result to establish the minimum and maximum variation allowed to the load in two predefined design set-ups that fulfills the time optimal single switching criteria. Finally, we make use of numerical simulations to show the performance of the proposed control under changes in the reference voltage and load resistance.