Evaluation of Cylindrical Asymmetric Surface Dielectric Barrier Discharge Actuators for Surface Decontamination and Mixing

Surface dielectric barrier discharge (SDBD) was used to evaluate cylindrical plasma actuators for inactivation of Salmonella enterica. A cylindrical SDBD configuration was evaluated to determine if the inherent induced body force could be leveraged to impel plasma species, such as reactive oxygen and nitrogen species (RONS), as an apparatus to sterilize surfaces. The cylindrical structure is evaluated in this study to observe whether an increase in mixing is possible to efficiently distribute the plasma species, thereby improving bacterial inactivation efficiency. The increase in induced airflow of SDBD actuators with increased numbers of electrodes correlates with increased bacterial inactivation. These results suggest that improving the particle velocity, airflow mixing tendencies, and plasma volume for the same power inputs (same net power to the actuators) results in increased surface decontamination efficiency.

Design and analysis of smoke flow visualization apparatus for wind tunnel

In the present study, the design and analysis of smoke generator are done for the low-speed wind tunnel. The wind tunnel fan is fitted with the Variable Frequency Drive to produce the wind speed in the range of 3 to 32 m/s with fan speed of 150 to 1500 rpm. The design of smoke generator was done according to Preston Sweeting mist generator principle corresponding to the free stream velocity of 3 m/s. A controlled smoke generator consisting of kerosene reservoir, controlled heater, blower, liquid column height adjustment mechanism, valves etc. was designed and fabricated. The smoke generator produced the smoke at the rate of 154 cm3/s which was close to the design flow rate of 149 cm3/s. To supply the required quantity of smoke in the wind tunnel, the smoke rake of NACA 0010 profile was developed and installed in the rapid contraction section of the wind tunnel to achieve the streamlined flow. The parametric studies were done on the smoke generator at different power inputs and its effects were studied on smoke temperature, smoke discharge and boiling time of the kerosene. The flow visualization was carried out on NACA 0015 airfoil model and the images were captured to examine the flow physics around them under different operating conditions.

Characterization of a Closed Loop Pulsating Heat Pipe Using Ethanol with Different Angles

In low-temperature difference, a closed-loop pulsating heat pipe (CLPHP) can be used as a cooling device due to its capability to transfer heat. The thermal performance of the CLPHP is affected by the working fluids. In this work, the effects of some operating parameters such as using ethanol as working fluid with 0.5 filling ratio, orientation, and power inputs are offered based on experimental study. Where the CLPHP was constructed and tested to achieve a better vision into the effect of orientation of 0°, 15°, 30°, 45°, and 90°, and power input of 50 W, 115 W, 215 W, and 450 W on the heat transfer characteristics and the thermal performance. The results indicated that the minimum thermal resistance can be reached at 0.1585 (℃/W) with an orientation of 90° and a power input of 450 W. The results revealed that the inclination angles and power inputs had considerable influence on the enhancement of the thermal performance of the CLPHP. For the low boiling temperature of the working fluid, the power input is more favorable because of fast startup compared with a high power input that leads to some difficulties like the dry-out phenomenon.

Electromechanical Performance Analysis of the Hybrid Piezoelectric-Electromagnetic Energy Harvester under Rotary Magnetic Plucking Excitation

This paper presents an analysis of the hybrid piezoelectric-electromagnetic energy harvester (P-EMEH) driven by contactless rotary magnetic plucking. A lumped-parameter model of the hybrid P-EMEH is developed, and the model parameters are determined from the finite element analysis (FEA) method. A parametric study is conducted to investigate the effects of driving force parameters, load resistance, and electromechanical coupling strengths (EMCSs) on the maximal displacements and velocities, average power inputs and outputs, and energy efficiencies of the system for indicating the performance of the hybrid P-EMEH. The results show that the hybrid P-EMEH can obtain the improved power inputs by reducing the gyration radii of the rotary magnet and shortening the gaps between the two magnets. The structural vibrations can be strongly suppressed owing to the optimal piezoelectric power outputs, which can lead to the occurrence of valleys’ power of the electromagnetic element. At weak coupling, the hybrid P-EMEH can achieve higher power outputs than the single piezoelectric energy harvester (PEH) and the single electromagnetic energy harvester (EMEH). At strong coupling, the use of the PEH is more advantageous for energy harvesting due to wider power bandwidths at high dimensionless frequencies when compared with the hybrid P-EMEH. This work provides a fundamental understanding on the effect of load resistance and EMCSs on the dynamic and electrical characteristics of the magnetically plucked hybrid P-EMEH.

On the Design of Continuously Variable Transmissions with Bidirectional Bridge Structures for Hybrid Vehicles

To increase the energy efficiency of road vehicles, an ideal transmission system should have a wide ratio coverage, a high torque capacity, and a high mechanical efficiency. Continuously variable units (CVUs) have been successfully implemented due to the smooth ratio variation, sufficient torque capacity, and ratio coverage. Hence, it will be beneficial to develop a hybrid powertrain comprising a CVU. In this paper, a design method called the “basic path diagram” (BPD) is proposed. It provides a simplified schematic of the system and represents the generic connections among the mechanical components. The system configurations synthesized by the BPD can be sorted according to three characteristics: Direction of power flows through the CVU, coupling pattern of the power inputs, and number of transmission paths parallel to the CVU. The first characteristic determines the number of times the CVU ratio coverage can be exploited, the second characteristic determines whether the torque of the power inputs can be independently controlled, and the third characteristic can help reduce the torque loading of the CVU. With the aid of a BPD, one of the possible system configurations is provided as an example. The result shows that the system can exploit twice the ratio coverage of the CVU and reduce the torque and power transmitted by the CVU in combination with planetary gearsets.

Renewal of Middle Wave Transmitters in Slovak Republic

This paper deals with the replacement of middle wave transmitters in Slovak Republic. The original transmitters were based on class C vacuum tube fundamentals and were produced by the Czechoslovakian group company Tesla. Class C transmitters were transmitting reliably to this day, however, the lifespan of these transmitters was nearing its end, moreover the need for a better quality analog modulated signal has pushed for its replacement and therefore they were replaced by modern, highly efficient class D transmitters, while utilizing the original infrastructure consisting of antennas and power inputs. Due to differences in characteristic parameters, however minor, this caused some significant problems, with impedance matching. To resolve these problems, it was necessary to implement a newly designed IMU (Impedance Matching Unit), while also securing a lightning strike protection. This paper has proposed a possibility of lightning surge protection of middle wave transmitters. The original protection implemented with the installations of class C transmitters was consisted only of multiple spark gaps. This kind of protection may prove inefficient using new class D transmitters. The device described in this paper has been designed and successfully implemented on a middle wave transmitter in Čižatice. This transmitter is transmitting with 5 kW power on the antenna with the carrier frequency of 702 kHz. Since the implementation of our device, the transmitter reports no failures and continues to transmit safely.

Improvement of a treatment processes of high-clayey gold-bearing placers

Characteristics of the placers with increased clayiness of gold-bearing bed and high content of fine and thin gold of the Far Eastern region, as well as technological approaches to processing, including the main process – disintegration, are analyzed. It is established that a reagentless gravitational working up based on generation of acoustic vibrations in fluid media is promising and requires its development. Energy-dispersive microanalysis by means of a scanning electron microscope, phase analysis using a diffractometer, as well as granulometric, dispersed and acoustic analyses have been applied to clay conglomerates selected at a high-clayey section of the deposit under consideration on the Malaya Nesterovka River in Primorskyi Krai. The presence of a wide range of noble metals, including gold and silver, rare earth and other elements was revealed. The data obtained on the composition and properties of clay conglomerates made it possible to determine the need for a more intensive process of the sand micro-disintegration to extract fine and thin particles of valuable components based on expanding the use of gravity technologies. It is noted that the known technologies would not ensure effective extraction of valuable components. A gravitational technology with cavitation reactors, which provide a power inputs reduction by several times in comparison with known devices, is proposed and validated. The hydrodynamic generator design is developed based on the concept of the fluid flow kinetic energy converting into the energy of hydroacoustic vibrations and jet streams of mineral hydromixtures in constrained conditions taking into account the similarity theory in modeling the cavitation processes. The proposed technology will reduce in-process losses of precious and other valuable metals, increase profitability and environmental safety in comparison with known processes.

Is the Ocean Speeding Up? Ocean Surface Energy Trends

A recent paper by Hu et al. (https://doi.org/10.1126/sciadv.aax7727) has raised the interesting question of whether the ocean circulation has been “speeding up” in the last decades. Their result contrasts with some estimates of the lack of major trends in oceanic surface gravity waves and wind stress. In general, both the increased energy and implied power inputs of the calculated circulation correspond to a small fraction of the very noisy background values. An example is the implied power increase of about 3 × 108 W, as compared to wind energy inputs of order 1012 W. Here the problem is reexamined using a state estimate that has the virtue of being energy, mass, etc. conserving. Because it is an estimate over an entire recent 26-yr interval, it is less sensitive to the strong changes in observational data density and distribution, and it does not rely upon nonconservative “reanalyses.” The focus is on the energy lying in the surface layers of the ocean. A potential energy increase is found, but it is almost completely unavailable—arising from the increase in mean sea level. A weak increase in kinetic energy in the top layer (10 m) is confirmed, corresponding to an increase of order 1 cm s−1 yr−1 over 26 years. An estimate of kinetic energy in the full water column shows no monotonic trend, but the changes in the corresponding available potential energy are not calculated here.