Operation of vibration source of an unbalance type with liquid-filled internal working chamber

Equipment for increasing water inflow to the well is proposed, which affects the aquifer by seismic vibrations. The method is based on accelerating the filtration process in soils, exposed to vibration. The equipment can work in conjunction with a submersible pump and has the ability to pump liquid through the working chamber of the generator. Generators can be combined into a group and driven by one electric motor to increase the efficiency of vibration treatment. This method is built into the existing technology of dewatering and pits drainage. The dynamics of the vibration source operation of an unbalance type with a liquid-filled inner chamber was studied in laboratory conditions, on a test. The vibration source was attached to the stand frame and was in a vertical position coaxially with the electric drive, thereby simulating its location in the well. The unbalance was unwound by an electric drive with a rotation frequency of 10 to 50 Hz in 5 Hz steps and seismic vibrations, generated by a vibration source, were recorded. Based on the experiments’ results, the amplitude-frequency characteristics of an unbalanced vibration source in the low-frequency range with a dry and liquid-filled inner chamber were obtained. In order to prevent the bearing assemblies from jamming, their heating was monitored with a thermal imager and temperature sensors.

Ion Source—Mathematical Simulation Results versus Experimental Data

To develop elements of a system for contact-free transportation of objects in space has now become an urgent task for the contemporary space-related activities. The purpose of work that is presented hereinafter was to conduct ground tests of the ion source, which is a key element of the above-mentioned system, and to compare the obtained experimental data with the mathematical simulation results in order to build a refined physical and mathematical model of the ion source. Such model was built on the basis of the classical problem regarding the motion of charged particles in an electrostatic field. Parameters of the ion source have been determined experimentally for several operating modes using various structural designs of the ion source electrodes. Two types of ion optics were tested—with slit and round apertures. Good correlation between simulation results and experimental data has been demonstrated. The optimum ion source operation modes have been identified to ensure minimum divergence angles for the plasma beam exiting from the ion source, which in its turn maximizes the pulse transmitted to the transported object.

Determination of an Effective Heating Radius in District Heating Systems in terms of Reliability

The paper presents a method developed to determine an effective heating radius (EHR) in district heating systems (DHSs) in terms of reliable heat supply to consumers. The search for EHR for various heating mains from the considered district heating source in DHS involves identifying heat source operation zones in various city areas. At the same time, apart from the search for EHR, the nodal reliability indices are estimated for each consumer and then used (if necessary) to adjust the obtained EHR. The paper briefly discusses some of the practical research results.

Reconfiguration Strategy for Fault Tolerance in a Cascaded Multilevel Inverter Using a Z-Source Converter

The cascade multilevel inverters are widely used in industrial manufacturing processes for DC-AC conversion. Therefore, the reliability and efficiency improvement, optimized control, and fault-tolerant strategies are areas of interest for researchers. The fault tolerance strategies applied to cascade multilevel inverters are classified as material redundancy and analytical redundancy. This paper presents the use of the Z-source converter as a fault reconfiguration method applied to a cascade multilevel inverter. On the one hand, the proposed approach has the characteristic of combining the use of material redundancy (modifying the output voltage by changing the Z-source operation), and on the other hand, it has the use of analytical redundancy (modifying the switching sequence of the multilevel inverter, changing from symmetrical to asymmetrical operation mode). This approach has been validated by experimental results of the system under fault-free conditions and employing the Z-source converter as the main fault reconfiguration element. The proposed fault reconfiguration strategy allows the cascaded multilevel inverter to continue to operate even in the presence of a fault by having continuous operation.

INFLUENCE OF METAL HYDRIDE HOLLOW CATHODE ON PENNING ION SOURCE OPERATION

The influence of metal hydride hollow cathode on a Penning ion source operation has been carried out. The feature of investigation is hydrogen injection only due to its desorption from metal hydride under ion-stimulated processes. The regimes of optimal discharge operation in the hollow cathode mode are determined. It has been revealed that the transition to the hollow cathode mode occurs at lower voltages, the discharge works without external gas supply, and the working pressure in the cell is set at the level determined by the discharge current. The supply of a negative bias to the metal hydride hollow cathode weakly affects the features of the emission of axial particles, although it allows the increase of plasma density near the metal hydride hollow cathode.

Process Drive Sizing Methodology and Multi-Level Modeling Linking MATLAB® and Aspen Plus® Environment

Optimal steam process drive sizing is crucial for efficient and sustainable operation of energy-intense industries. Recent years have brought several methods assessing this problem, which differ in complexity and user-friendliness. In this paper, a novel complex method was developed and presented and its superiority over other approaches was documented on an industrial case study. Both the process-side and steam-side characteristics were analyzed to obtain correct model input data: Driven equipment performance and efficiency maps were considered, off-design and seasonal operation was studied, and steam network topology was included. Operational data processing and sizing calculations were performed in a linked MATLAB®–Aspen Plus® environment, exploiting the strong sides of both software tools. The case study aimed to replace a condensing steam turbine by a backpressure one, revealing that: 1. Simpler methods neglecting frictional pressure losses and off-design turbine operation efficiency loss undersized the drive and led to unacceptable loss of deliverable power to the process; 2. the associated process production loss amounted up to 20%; 3. existing bottlenecks in refinery steam pipelines operation were removed; however, new ones were created; and 4. the effect on the marginal steam source operation may vary seasonally. These findings accentuate the value and viability of the presented method.