Repetitive Operation Research Articles

Research on 3-GW Repetitively Operating Relativistic Backward Wave Oscillator

Relativistic backward wave oscillator (RBWO) is a promising high-power microwave (HPM) generator. In past decades, many efforts have been devoted to improving its practicality, in which the repetitively operating RBWO has drawn much attention. However, two bottlenecks once limited its development. One is the generation of massive anode plasmas or even damage of the collector, and the other is the RF breakdown of electrodynamic structures. This article describes an RBWO which can operate repetitively with 3-GW microwave power by mitigating these two problems. First, a titanium collector, which shows better performance in resisting electron beam bombardment than the conventional stainless steel collector, is adopted. Meanwhile, water-cooling technology is applied to expedite heat dissipation of the collector. Second, since our investigations demonstrate that an anodic mechanism, not the conventional cathodic mechanism, is the main cause for RF breakdown of electrodynamic structures under strong guiding magnetic field, the titanium material is also used to manufacture the electrodynamic structures of the RBWO in order to increase its power capacity. The advantage of the titanium RBWO is verified in experiments. The application of these techniques, as well as some important surface treatment techniques such as polishing, ultrasonic washing, and vacuum baking, leads to the stable repetitive operation of the RBWO with 3-GW output power and 25-ns microwave duration under a repetition rate of 50 Hz. The successive operation time of the device is up to 20 s.

Resolving the Theoretically Irreconcilable: Aldo Rossi’s Giant Kitchenware Models as Generative Object--Subjects

This essay investigates Aldo Rossi’s coffee vessel models as exhibited in his “Domestic Theater” project as a mediator between conflicting ideas in his architectural and urban theory. Entangled with Rossi’s paintings, kitchenware designs, and architectural projects, the coffee vessel models derived from both imaginary fantasies and manufactured utensils, modeling various conceptual and practical prototypes that characterize his corpus at large. Negotiating between human beings and lifeless artifacts, domestic objects and theatrical settings, fictional scenes and real-world objects, the scale-less and displaced kitchenware models accommodate the contradictions of Rossi’s theory. By analyzing the analogical and repetitive operations in their development process, these models are posited as autonomous, generative and impenetrable object-subjects that engagingly advance architectural theory in a disciplinary sense. I argue that it is the physical existence of the kitchenware models—not the textual elaborations and logical deductions—that masters Rossi’s unresolved struggle between dissonant yet irreducible ideas, and completes “the difficult whole.”

Effect of gas type on insulation recovery performance and repetitive breakdown stability of a corona-stabilized plasma closing switch

The corona-stabilized plasma closing switch, which utilizes the stabilization effect resulted from the movement and accumulation of corona-generated space charge to improve the repetitive performance, has a great potential in repetitive pulsed power systems. In this paper, the influence of gas type on the recovery performance and repetitive breakdown stability of a corona-stabilized plasma closing switch is investigated. The results are analyzed from the memory effect of residual plasma, the development and propagation characteristics of streamer corona, and the thermo-hydrodynamic process of discharge channel. The enhancement effect of residual plasma on corona stabilization of the subsequent breakdown in the repetitive operation of the gas gap with highly inhomogeneous electric field and strong electronegative gas is proposed. The development and propagation characteristics of streamer corona in different gases that can lead to significant differences in the corona stabilization effect of breakdown are clarified. It is also found that the gas with small molecular mass and higher gas velocity exhibits excellent insulation recovery in the gas switch with uniform fields, but displays poor repetitive performance in the corona-stabilized switch with a rod-plate electrode.

Analysis of Solutions Dedicated to Non-Conformity Prevention

Purpose: The purpose of the work is to analyze the use of solutions aimed at preventing incompatibilities and assess the effectiveness of these solutions to minimize the risk associated with the quality of manufactured products. The analysis presented in the work is based on the Poka-Yoke error prevention concept used in the selected enterprise. The paper presents the state of the company before and after the introduction of Poka-Yoke method. Approach/Methodology/Design: The research methods used in the paper were the analysis of company data, analysis of literature states, as well as methods using the Poka-Yoke concept. The company was surveyed in 2017/2018 during the system implementation. Findings: The results on the control card for nonconforming units of type p were also presented, where the analysis showed that the introduction of the Poka-Yoke system to the company reduced the number of nonconformities by 6.69%. Practical Implications: Implementation of the Poka-Yoke system will allow enterprises to create conditions in which an error cannot happen, or will be immediately visible. The result of such an action may be distracting operators from repetitive operations, reducing the number of deficiencies and induce immediate action when a problem occurs. Originality/Value: Showing how the use of the Poka-Yoke system affects the prevention of inadvertent error in enterprises, by determining the differences between the state of the enterprise before and after the introduction of the Poka-Yoke system, there is an opportunity to improve the economy and contribute to the social and economic sphere.

Run-to-Run Control With Bayesian Optimization for Soft Landing of Short-Stroke Reluctance Actuators

There is great interest in minimizing the impact forces of reluctance actuators during commutations, in order to reduce contact bouncing, acoustic noise, and mechanical wear. In this regard, a run-to-run (R2R) control algorithm is proposed to decrease the contact velocity, by exploiting the repetitive operations of these devices. The complete control is presented, with special focus on the optimization method and the input definition. The search method is based on Bayesian optimization, and several additions are introduced for its application in R2R control, e.g., the removal of stored points and the definition of a new acquisition function. Additionally, methods for the input parameterization and dimension reduction are presented. For analysis, in this article, Monte Carlo simulations are performed using a dynamic model of a commercial solenoid valve, comparing the proposed search method with two alternatives. Furthermore, the control strategy is validated through experimental testing, using several devices from the same ensemble of solenoid valves.

Temporal contrast enhancement of ultrashort pulses using a spatiotemporal plasma-lens filter.

The spatiotemporal plasma-lens filter proposed here enhances the temporal contrast of the ultrashort pulse laser by combining plasma optics and spatial filtering. Experimentally, the spatiotemporal plasma-lens filter has improved the temporal contrast by 2 orders of magnitude with 80% laser transmission efficiency under a 1 Hz repetitive laser operation. Not only were the pre-pulse and the pedestal cleaned out, but also the rising edge of the main pulse was sharpened.

Compact Integration and RF Commissioning of the C-Band 9-MeV Electron Linear Accelerator at the Dongnam Institute of Radiological & Medical Sciences

The 6-MeV C-band standing-wave accelerator was constructed in 2015 and is providing for the beam service. The new 9-MeV accelerator was designed and constructed in 2018 at the Dongnam Institute of Radiological & Medical Sciences (DIRAMS), Busan, Korea. The 5712 MHz accelerating column was designed with an average accelerating gradient of 16.7 MV/m at a pulsed resonance frequency (RF) power of 2.5 MW. The C-band coaxial magnetron was chosen for its high RF power of 2.5 MW and RF frequency of 5712 ± 10 MHz. While the 6-MeV accelerator was operating using a magnetron manufactured by BVERI, China, the 9-MeV accelerator uses a magnetron manufactured by CPI, USA. Though the CPI magnetron requires more heating power and precise heating control for high repetition operation, the frequency spectrum and the RF power distribution are satisfactory for our accelerating columns. The magnetron installed on the 9-MeV accelerator was tested with the 6-MW pulse modulator based on the thyratron-switched pulse-forming network and is currently operating for accelerator RF conditioning. In this paper, we present a brief description of the 9-MeV accelerator, the integration of the RF transport systems and the commissioning status. We also discuss the results obtained during the early commissioning and future plan.

Potential use of plasma focus radiation sources in superficial cancer therapy

The new multidisciplinary field of plasma medicine combines plasma physics, electrical engineering, life sciences and clinical medicine. Bekeschus et al. [Plasma Processes Polym. 16, 1800033 (2019)]. Here we explore potential uses in medicine, most particularly cancer therapy, the plasma source being brought out of the field of industrial applications into the life sciences, the focus being on superficial cancer radiotherapy strategies. Existing radiotherapy practices for such cancers rely on the use of rather large facilities, most popularly the electron linear accelerator and X-ray tube-based devices. Conversely, a compact plasma radiation source can be housed in a relatively small space, there being considerable promise for such devices to produce the fluence requirements of radiotherapy for treatment of skin cancers. The present study of feasibility investigates the plasma focus device, with the emission produced by a single discharge shown to generate an X-ray dose of few tens of mGy. The X-ray dose is the integration of emission in the discharge durations of less than a μs, it is therefore possible using these devices to build up fractional irradiation dose through repetitive operation of the discharge system.

Data driven model free adaptive iterative learning perimeter control for large-scale urban road networks

Most perimeter control methods in literature are the model-based schemes designing the controller based on the available accurate macroscopic fundamental diagram (MFD) function with well known techniques of modern control methods. However, accurate modeling of the traffic flow system is hard and time-consuming. On the other hand, macroscopic traffic flow patterns show heavily similarity between days, and data from past days might enable improving the performance of the perimeter controller. Motivated by this observation, a model free adaptive iterative learning perimeter control (MFAILPC) scheme is proposed in this paper. The three features of this method are: (1) No dynamical model is required in the controller design by virtue of dynamic linearization data modeling technique, i.e., it is a data-driven method, (2) the perimeter controller performance will improve iteratively with the help of the repetitive operation pattern of the traffic system, (3) the learning gain is tuned adaptively along the iterative axis. The effectiveness of the proposed scheme is tested comparing with various control methods for a multi-region traffic network considering modeling errors, measurement noise, demand variations, and time-changing MFDs. Simulation results show that the proposed MFAILPC presents a great potential and is more resilient against errors than the standard perimeter control methods such as model predictive control, proportional-integral control, etc.

OPTIMIZATION OF PROFESSIONAL ACTIVITY IN OPERATORS OF MORNING CHRONOTYPE BASED ON BIOELECTRICAL FEATURES OF BRAIN

Biorhythmological features and electroencephalography parameters in operators of morning chronotype demonstrate a significant mutual influence. In particular, frequency of the low-frequency beta-rhythm in left central leads and the total result of Ostberg-Stepanova test have an inverse correlation of average strength (rs = -0,697), which reflects the expressed ability of these operators to perform stereotypical, routine mental operations. In addition, total result of Ostberg - Stepanova test has a strong inverse correlation with frequency of low-frequency beta-rhythm in right central (rs = -0,704) and right temporal leads (rs = -0,738). This indicates that «pronounced larks» have the ability to quickly and efficiently perform repetitive mental operations, especially those associated with the impact of non-verbal auditory stimuli.

Microstructure modification and corrosion improvement of [formula omitted] steel induced by pseudospark electron beam treatment

The pseudospark electron beam is a kind of pulsed electron beam characterized by fast and stable repetitive operations. It is able to achieve high rate of energy rise and plasma quenching. Thus, when used as an intense electron beam source for material processing, some unique properties are induced. The mechanism analysis of microstructure modification and corrosion improvement of AISI1045 steel treated by pseudospark electron beam are investigated. Results show that the amorphous phase is formed on the top surface of melted layer. The treated layer is several microns deep with nonuniform interface. Besides, material’s grain sizes are significantly reduced after pseudospark treatment. The average grain size in the heat affected zone is smaller than that in the melted zone, which is attribute to the combination effect of temperature-induced dynamic thermal stress fields and the highest temperature gradient. Furthermore, electrochemical impedance spectroscopy (EIS) and potential polarization analysis are used to study the corrosion behavior of samples pre and post pseudospark electron beam treatment. The improvement of corrosion resistance is due to the combination effects of the formation of austenite, the removement of impurities during the electron beam surface treatment process and the formation of the amorphous phase acted as a homogeneous passive film.

A mesoporous SiO2 thin films-based ionic decision-maker for solving multi-armed bandit problems

An ionic decision-maker (IDM), with the remarkable ability to solve multi-armed bandit problems (MBPs), has been developed as a new artificial intelligence technology, which have humanlike decision-making capabilities. Owing to their low durability, the Nafion polymer electrolytes and electrode materials normally found within IDMs do not meet the high-level integration and repetitive operation requirements of such devices. Therefore, in this study, mesoporous SiO2, which is a proton conducting inorganic oxide, has been utilized as the IDM electrolyte. The oxide-based IDMs developed showed good solvability for MBPs and excellent adaptability to dramatic environmental shifts, which were both at similar levels to those found in Nafion-based IDMs. While the adaptation exhibited by the oxide-based IDMs was slightly inferior to that found in Nafion-based IDMs, fluctuations in the correct selection rate (CSR) were significantly improved over those observed in Nafion-based IDMs. Further, the average of reached CSR was enhanced to 0.96 in comparison to 0.92 for Nafion-based IDMs.

Impact of Using a Filter in a Direct Gasoline Injection Engine Exhaust System on the Emitted Particle Mass and Number

Abstract The article presents emission test results comparison carried out on a dynamic engine dynamometer. Parameters were recorded during a drive made in accordance with the requirements of the RDE. Test bench allowed to determine the particle mass and number emission in the repetitive engine operation conditions. One of three used elements wan an OEM solution from one of particulate filters producers, the other was intended for use in original systems, the third was a custom product. The highest efficiency of particulate filtration was demonstrated by the last filter, which was adapted to the engine.

The Effect of Multiple Surgeries on Psychosocial Outcomes in Pediatric Patients: A Scoping Review.

Birth defects affect 3% of all babies born in the United States each year. Unlike reconstruction for many acquired deformities, one hallmark of reconstruction for complex congenital conditions is the requirement of multiple surgeries, procedures, and therapies from birth to maturity. These interventions often result in significant medical burden on children during development with potential long-term psychosocial consequences. The aim of this study was therefore to better define the psychosocial impact of repetitive operations on the pediatric patient. A scoping review was performed under the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Review guidelines. We searched the PubMed, Cochrane Library, Science Direct, and Web of Science databases using key words "number of surgeries," "psychosocial," "pediatric," and related terms. Primary articles published in English describing psychosocial outcomes in pediatric patients who underwent more than one procedure or surgery were included (n = 25). The Newcastle-Ottawa Scale was used to assess the quality of each study. We included 25 articles published between 1995 and 2019, which included 6520 patients. The most common diagnosis across all studies was congenital heart disease (CHD) (n = 4169, 63.9%), followed by cleft lip and palate (n = 1196, 18.3%). The average number of operations and procedures was 3.4 (range = 1-18) and 32.1 (range = 6-89), respectively. The association between repetitive surgeries and poorer psychosocial outcomes was demonstrated in children with early-onset scoliosis, CHD, hydrocephalus, bladder exstrophy, posterior urethral rupture, anorectal anomalies, and conditions requiring numerous nonsurgical procedures. There were also a few CHD, cleft lip and/or palate, and hydrocephalus studies that did not find a significant correlation. The studies here suggest that certain pediatric patient populations are at risk for impaired psychosocial functioning as a result of repetitive procedures. However, it is important to differentiate whether the association with poorer psychosocial outcomes is from the number of surgical procedures or whether the number if just a surrogate for increased disease complexity. Standardized psychosocial outcomes measures and future prospective, long-term, randomized clinical trials are also warranted.

A Colony Picking Control System Based on Machine Vision

With rapid growth of the number of genomic sequences, researchers are faced with the task of managing huge clone libraries. A single experiment may involve classifying tens of thousands of bacterial, yeast or phage colonies. While, repetitive manual operation is followed by a lower efficiency and accuracy of colony picking and inoculating, leading to the fail in high throughput. In order to improve the efficiency and accuracy of colony picking process, this paper introduces a prototype, which picks colonies automatically. After analysis of colony picking process, we develop a colony picking control system based on industrial computer and CCD camera. Beyond that, we put forward the design of hardware and software of system. Finally, picking and inoculating colonies, as well as cleaning and heating needles come true.

An Energy-Quality Scalable STDP Based Sparse Coding Processor With On-Chip Learning Capability.

Two main bottlenecks encountered when implementing energy-efficient spike-timing-dependent plasticity (STDP) based sparse coding, are the complex computation of winner-take-all (WTA) operation and repetitive neuronal operations in the time domain processing. In this article, we present an energy-efficient STDP based sparse coding processor. The low-cost hardware is based on the algorithmic reduction techniques as following: First, the complex WTA operation is simplified based on the prediction of spike emitting neurons. Sparsity based approximation in spatial and temporal domain are also efficiently exploited to remove the redundant neurons with negligible algorithmic accuracy loss. We designed and implemented the hardware of the STDP based sparse coding using 65nm CMOS process. By exploiting input sparsity, theproposed SNN architecture can dynamically trade off algorithmic quality for computation energy (up to 74%) for Natural image (maximum 0.01 RMSE increment) and MNIST (no accuracy loss) applications. In the inference mode of operations, the SNN hardware achieves the throughput of 374 Mpixels/s and 840.2 GSOP/s with the energy-efficiency of 781.52 pJ/pixel and 0.35pJ/SOP.

Calibration-based tool condition monitoring for repetitive machining operations

Reliable tool condition monitoring (TCM) system is essential for any machining process in mass production to control the part quality as well as reduce the machine tool downtime and maintenance costs. However, while various research studies have proposed their TCM systems, the complexity in setups with advanced decision-making algorithms and specificity in application to limited cutting conditions continue to complicate the implementation of these systems into practical scenarios. This study develops a very simple and flexible TCM system for repetitive machining operations. The proposed monitoring approach reduces the complexity of monitoring model by considering the important characteristic of repeatability in process which has been commonly found in the mass production scenario and implements the calibration procedure to improve the flexibility of the model application to actual machining processes with complex toolpath designs and variable cutting conditions. The selected cutting tools with specific tool conditions are used in the calibration phase to generate reference signals. In actual repetitive production, the collected signal generated by the cutting tool in each operation is compared with reference signals to identify the most similar condition of the reference tool through the proposed similarity analysis. To validate the performance, the current study demonstrates the application of proposed monitoring approach to monitor the tool wear in repetitive milling operations with complex toolpath, and the predicted tool wear progression is found to be in good agreement with experimental measurements during the machining of multiple parts over the entire tool life.

An Efficient Relational Database Keyword Search Scheme Based on Combined Candidate Network Evaluation

Relational keyword search (R-KWS) systems provide users with a convenient means in relational database queries. There exist two main types of R-KWS: those based on Data Graphs and those based on Schema Graphs. In this paper, we focus on the latter, R-KWS based on Schema Graphs. Most existing methods are typically inefficient due to the large number of repetitive operation caused by overlapping candidate networks and the execution of lots of complex queries. We present the R-KWS approach based on combined candidate network evaluation to improve the query efficiency. The proposed Combined Candidate Network (CCN) can efficiently share the overlapping part between candidate networks, and then avoid the repetitive operation during the evaluation of candidate networks. Meanwhile, CCN possesses another important characteristic that candidate networks within a CCN are still identifiable after candidate networks being compressed into a CCN. We design an algorithm based on this characteristic to evaluate CCN for the generation of final query results. This algorithm is able to eliminate the execution of a large number of complex queries required by most existing approaches, and thus significantly improve the efficiency of keyword search. Experiments on real datasets show that our approach can improve query efficiency without any loss of the quality of query results with respect to existing approaches.

Microstructure modification of AISI1045 steel induced by high-current pulsed pseudospark electron beam

Pseudospark electron beam is a kind of high-current pulsed electron beam. It is characterized by high current (hundreds of amperes to thousands amperes), short pulse duration (hundreds of nanoseconds to thousands nanoseconds), high frequency (hundreds Hz to thousands Hz) and self-focused beam diameter (typically 0.5-5 mm), which are more favorable for metal surface treatment compared with the conventional thermal-emission electron beam diode. The pseudospark electron beam is easy to achieve high rate of beam energy rise, plasma quenching and to obtain fast and stable repetitive operation. Some unique properties of material processing applications have been induced by the pseudospark electron beam treatment. In this paper, the mechanism and microstructure modification of AISI1045 steel by pseudospark electron beam surface treatment have been investigated. Surface microstructure and chemical composition of AISI 1045 steel pre and post pseudospark electron beam treatment are investigated by using scanning electron microscope (SEM), electron back-scattered diffraction (EBSD) and transmission electron microscope (TEM). Results show that the average depth of the treated layer is several microns. The melt interface is not straight, indicating a non-uniform melting process. Besides, material’s grain size is significantly reduced after pseudospark treatment, especially in sublayer. The average grain size in the sublayer is smaller than in the top-layer. The relatively finer grain size in the sublayer is attributed to the temperature-induced dynamic thermal stress fields and the highest temperature gradient in the subsurface layer instead of on the top layer. Furthermore, the amorphous phase is observed on the surface of melted layer.

Developments of Pulsed Electron Beam Sources for High-Power Microwave Applications

High-current pulsed electron beam sources are the core components of high-power microwave systems. In order to meet the requirements of future applications, one needs to improve the performance of electron beam sources in terms of vacuum insulation, beam transportation, and thermal management. In this paper, we report about our recent progress in the development of high-current vacuum electron beam sources. In order to meet the vacuum maintenance requirements of high-power microwave tubes, a high-electric field ceramic vacuum interface is designed and fabricated based on the ceramic metal brazing technique. In our experiments, a stable operation of the ceramic vacuum interface is demonstrated in the 10 Hz repetition mode with withstand voltage of larger than 600 kV and pulse width of about 100 ns. Besides, a cold cathode is developed using SiC nanowires, and an average beam current density of 1.2 kA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> is achieved under the electric field strength of 90 kV/cm. Compared with traditional velvet cathodes, the characteristics of the SiC nanowire cathode, such as macro-electrical stability, emission uniformity, and operating life have been significantly improved. Furthermore, a high-current electron beam collector has been developed for relativistic backward wave oscillator tubes. A spiral flume is designed in the collector to meet the requirement of both high specific energy and low flow rate. It shows that the withstand heat flow density is in the order of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup> W/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , which is suitable for the long pulse and repetitive operation of the system. These results represent a significant step towards the practical application of long-life high-power microwave systems.