Conventional Mode Research Articles

Distance Learning at the Conventional Campus-based College

Due to the Covid-19 pandemic, practically all colleges and universities in the United States shifted their conventional instructional mode of the in-person face-to-face classroom teaching to the virtual online instruction in the middle of the spring 2020 semester. While online-only institutions, majority of which are for-profit, eagerly promoted their online education, all of the conventional colleges and universities struggled to provide the necessary training for the instructional faculty and to assure students and their parents that the quality of their college education would not be compromised. In this research, we explored the impact of such quickly adopted online instruction as an inevitable alternative during the pandemic on the student learning as the pandemic placed them in a natural quasi field experimental condition. We found a significant difference in the student learning outcome recorded in the semester grade between the two periods: the difference is particularly prominent in non-participation or withdrawal from the learning process as reported in the grades of fails and withdrawals. Implications of the study for college and university enrollment and the compelling need for further study are discussed.

SPDTS: A Differential Privacy-Based Blockchain Scheme for Secure Power Data Trading

Currently, the conventional mode of power data transaction is mediated by Web pages. Nevertheless, there are challenging issues such as privacy protection, transaction security and data reliability in power data trading. In this paper, we present a novel secure power data trading scheme (SPDTS). Firstly, the zero-knowledge proof is employed to achieve data availability and consistency without revealing the data. Then, SPDTS takes full advantage of the dispersibility and immutability of blockchain to ensure the reliability of data transactions. To keep the transaction process efficient, the processing tasks for power data are performed under smart contract. Meanwhile, a trusted execution environment (TEE) is adopted to guarantee the security of power data. Finally, we present a differential privacy scheme to safeguard the privacy information in the power data. Our study indicates that the proposed scheme can achieve privacy protection, transaction security and data reliability. Also, we conduct security analysis and verify the privacy protection property of the scheme in real cases.

Ideal single mode laser operation with single drive conventional/phase shift Mach–Zehnder modulators measured in optical access networks

Abstract The work outlined ideal single mode laser operation with single measured drive phase shift/conventional Mach–Zehnder modulators (MZM) in optical access networks is simulated and analyzed. Maximum signal power level versus spectral wavelength and time domain spectrum after fiber channel based 1.5 splitting ratio conventional/phase shift MZM and Idea single mode laser is measured accurately. Maximum Q coefficient of 35.87 and mini bit error rates of 2.3279 × 10−282 in the case of conventional MZM and idea single mode laser. Maximum Q coefficient of 17.86 and mini error rate of 1.0376 × 10−71 in the case of phase shift MZM and Idea single mode laser.

Intelligent Blanking of Silicon Steel Coil in a Transformer Core Oriented to Green Manufacturing

For transformer enterprises, energy consumption and environmental pollution mainly occur in the manufacturing process. The conventional manufacturing mode does not conform to the current green manufacturing mode. The green manufacturing mode requires enterprises to improve the transformer production technology, the utilization rate of materials and equipment, and the production efficiency and to achieve clean production through energy conservation and consumption reduction. The main objective of this research is to schedule the blanking of multiple transformer cores together rather than the conventional calculation conducted one by one. An optimization model of the silicon steel coil blanking is established, an evaluation method for blanking schemes is proposed, algorithms to solve the optimization model are analyzed in detail, and the solving processes and results are compared through a case study. Compared with the current manual calculation, this paper is of practical significance for transformer manufacturers to improve the production efficiency, reduce material waste, meet the personalized market demand characterized by multiple varieties and small batches, and achieve the green manufacturing of transformers.

Left bundle branch area pacing: A promising modality for cardiac resynchronization therapy.

Cardiac resynchronization therapy (CRT) is recognized as the first-line management for patients with heart failure (HF) and conduction disorders. As a conventional mode for delivering CRT, biventricular pacing (BVP) improves cardiac function and reduces HF hospitalizations and mortality, but there are still limitations given the high incidence of a lack of response rates. Alternative pacing methods are needed either for primary or rescue therapy. In recent years, conduction system pacing (CSP) has emerged as a more physiological pacing modality for simultaneous stimulation of the ventricles, including His bundle pacing (HBP) and left bundle branch pacing (LBBP). CSP activates the His-Purkinje system, allowing normal ventricular stimulation. However, HBP is technically challenging with a relatively low success rate, high pacing threshold, and failure to correct distal conduction abnormalities. Therefore, LBBP stands out as a novel ideal physiological pacing modality for CRT. Several non-randomized studies compared the feasibility and safety of LBBP with BVP and concluded that LBBP is superior to BVP for delivering CRT with a narrower QRS and greater improvements in left ventricular ejection fraction (LVEF) and New York Heart Association (NYHA) functional class. Concurrently, some studies showed lower and stable pacing thresholds and greater improvement of B-type natriuretic peptide (BNP) levels, as well as better mechanical synchronization and efficiency. LBBP ensures better ventricular electromechanical resynchronization than BVP. In this review, we discuss current knowledge of LBBP, compare LBBP with BVP, and explore the potential of LBBP to serve as an alternative primary therapy to realize cardiac resynchronization.

An exploration of instructional behaviors of a teacher in a mobile learning context

Mobile learning has been frequently adopted, but it is necessary to explore how teachers face the challenges. In this study, an experienced teacher's teaching behaviors were collected and analyzed through sequential pattern analysis. Also, an interview with the teacher was conducted. The result showed that the teacher put a great deal of effort into creating a positive learning atmosphere. His teaching behavioral pattern in mobile learning was more scattered than that in conventional teaching mode. This might be the biggest challenge for novice teachers. Finally, this study found that the students' basic digital skills were also a vital element.

Piezoelectric hybrid actuation mode to improve speeds in cross-scale micromanipulations

Piezoelectric precision actuators are powerful tools used to explore and reform the microworld. A large number of achievements have emerged to promote their progress. However, most of them only focus on high accuracies and large workspaces, but ignore the roles of fast speeds for high working efficiencies and wide application fields. Inspired by the wobbling and jumping gaits of the cricket, a hybrid actuation mode for piezoelectric actuators is proposed to improve speeds in cross-scale micromanipulations. After solving three key problems of physical design, operation method and control strategy, this idea is verified with FEM simulations and theoretical models. The experiments indicate that the hybrid mode increases the speed by about 300% over the conventional walking mode, and the maximum speed reaches about 3.9 mm/s (0.16 rad/s). Furthermore, the resolution is as high as 3.8 nm (0.14 μrad), and the RMS positioning error is smaller than 34.2 nm in a stroke of 1 mm. With unlimited stroke, fast speed and high precision, the hybrid mode is very suitable for the accurate quick positioning in a large range. The experiment also demonstrates great potential applications in micro-nano assemblies. To sum up, the hybrid mode significantly improves the speeds of piezoelectric actuators under the premises of high accuracies and large workspaces. Besides, this mode is a universal approach, which can be easily applied on other actuators to improve speeds, so it is helpful to expand applications of piezoelectric precision actuators.

Efficiency of the autonomous modular system in the implementation of the spray application process in the vineyard

Autonomous modular system mounted on a conventional (CON) sprayer operating on the principle of pulse-width modulation (PWM) control of electromagnetic valves represents state-of-the-art technology for implementation controlled application of spray mixture without changing the operating parameters of the sprayer (e.g. spray pressure, nozzle size). In accordance with the principles of precision viticulture, the pulse width modulation control is the primary technology, which allows the application of the required amount of spray mixture exclusively to the target areas of the vine without changing the droplet size spectrum and allows for even deposit quality and reducing the drift outside the target areas. In the vineyard, we tested an autonomous axial sprayer prototype throughout the entire spraying season in 2021 on which we have installed an autonomous modular system with enabled pulse-width control. We tested two modes of operation of the sprayer prototype, namely autonomous (continuous duty cycle control (DC: 0 to 100%)) and conventional (nozzle fully open at all time), at a steady spray speed of 6 kmh-1. We compared the amount of PPP expressed as a percentage between autonomous and conventional mode of operation of the sprayer through individual nozzles on the sprayer. The maximum saving of the spray mixture of 69.8%, through an individual nozzle was measured at phenological stage of the vine BBCH 55. A comparative analysis between the CON and PWM mode of the spray mixture application showed that we saved 626.24 l per year in the automated mode of operation.

Material-Specific Roadmap Modes Can Improve the Visibility of Liquid Embolic Agents for Endovascular Embolization: A Systematic In Vitro Study.

Endovascular embolization using liquid embolic agents is a safe and effective treatment option for AVMs and fistulas. Because reliable visibility of these liquid embolic agents is essential for intraprocedural visual control to prevent complications, novel angiographic systems are equipped with material-specific roadmap modes. The aim of this study was the systematic in vitro comparison of conventional and material-specific roadmap modes regarding the visibility of the most used liquid embolic agents. A recently introduced in vitro model, resembling cerebral vessels, was embolized with Onyx 18, Squid 18, PHIL 25%, and n-BCA mixed with iodized oil (n = 4 for each liquid embolic agent), as well as with contrast medium and saline, both serving as a reference. Imaging was performed in conventional and material-specific roadmap modes. The visibility of the liquid embolic agents in both modes was compared quantitatively and qualitatively. Significant differences between conventional and material-specific roadmap modes regarding the visibility of the liquid embolic agents were observed for all study groups. All liquid embolic agents were better visible in the material-specific roadmap modes compared with the conventional mode in qualitative and quantitative analyses (eg, Onyx in conventional-versus-material-specific modes along the 1.0-mm sector: mean contrast-to-noise ratio, 5.69 [SD, 0.85] versus 47.18 [SD, 5.72]; P < .001, respectively). In this in vitro study, we demonstrated a better visibility of all investigated liquid embolic agents by using material-specific roadmap modes compared with the conventional roadmap technique. Especially in complex anatomic situations, these novel roadmap modes could improve the visual control and thus the safety and efficacy of embolization procedures in clinical practice.

The use of cardiac CT acquisition mode for dynamic musculoskeletal imaging

ObjectivesTo quantitatively evaluate the impact of a cardiac acquisition CT mode on motion artifacts in comparison to a conventional cine mode for dynamic musculoskeletal (MSK) imaging. MethodsA rotating PMMA phantom with air-filled holes drilled at varying distances from the disk center corresponding to linear hole speeds of 0.75 cm/s, 2.0 cm/s, and 3.6 cm/s was designed. Dynamic scans were obtained in cardiac and cine modes while the phantom was rotating at 48°/s in the CT scanner. An automated workflow to compute the Jaccard distance (JD) was established to quantify degree of motion artifacts in the reconstructed phantom images. JD values between the cardiac and cine scan modes were compared using a paired sample t-test. In addition, three healthy volunteers were scanned with both modes during a cyclic flexion–extension motion of the knee and analysed using the proposed metric. ResultsFor all hole sizes and speeds, the cardiac scan mode had significantly lower (p-value <0.001) JD values.(0.39 [0.32–0.46]) i.e less motion artifacts in comparison to the cine mode (0.72 [0.68–0.76]). For both modes, a progressive increase in JD was also observed as the linear speed of the holes increased from 0.75 cm/s to 3.6 cm/s. The dynamic images of the three healthy volunteers showed less artifacts when scanned in cardiac mode compared to cine mode, and this was quantitatively confirmed by the JD values. ConclusionsA cardiac scan mode could be used to study dynamic musculoskeletal phenomena especially of fast-moving joints since it significantly minimized motion artifacts.

Updating the FMEA Approach with Mitigation Assessment Capabilities—A Case Study of Aircraft Maintenance Repairs

This paper proposes a qualitative model to overcome the limitations of conventional failure mode and effects analysis (FMEA), which does not consider risk mitigation capabilities when prioritizing risks. Failure to consider these capabilities can lead to unrealistic risk estimates, especially when the level of uncertainty is high. In the proposed model, the original applicability of conventional FMEA was retained along with the three conventional risk variables, namely, severity, occurrence, and detectability. In addition, a fourth variable was added to account for risk mitigation capabilities. A case study in the project selection of aircraft repairs was used to demonstrate the implementation of the model and its applicability. The results show that the inclusion of mitigation options leads to more realistic risk scenarios, suggesting that the original FMEA approach may lead to non-conservative risk estimates.

Effect analysis of a virtual simulation experimental platform in teaching pulpotomy

BackgroundThe experimental teaching of pediatric dentistry is a bridge between theoretical study and clinical practice, and virtual simulation technology provides a new method of instruction.MethodsWe built an experimental teaching platform using virtual simulation technology for vital pulpotomy that includes learning and examination modes. A total of 199 students majoring in stomatology in the fourth year at Sun Yat-Sen University were randomly divided into a control group (conventional teaching mode) and an experimental group (virtual simulation experimental teaching model). The teaching effect was evaluated by theoretical and experimental examination.ResultsWe found that both the theoretical and experimental scores of the experimental group were higher than those of the control group, and the theoretical scores of the experimental group after exposure to the virtual simulation experimental teaching platform were also higher than those before the class, with significant differences (P < 0.05). Feedback from the experimental group after the class indicated that the platform reinforced their theoretical knowledge and greatly improved their mastery of operational skills.ConclusionsThe application of a virtual simulation experimental teaching platform can effectively improve the teaching of pulpotomy.

Performance analysis and operation strategy of a dual-evaporation temperature heat pump system for electric vehicles in winter

With increasingly serious environmental and energy issues, efficient and environmentally friendly electric vehicles have received more attention. However, the high heating and dehumidification energy consumption of their air conditioning system reduces their driving range in winter, giving passengers and drivers range anxiety. In this study, a dual-evaporation temperature heat pump system is proposed to reduce the energy consumption of electric vehicle air conditioning systems in winter, and a simulation model of the proposed system is developed. First, the volume ratio of the dual-cylinder compressor is optimized. Subsequently, the performance of the proposed system in various operation modes under different ambient conditions is compared. The results indicate an optimized volume ratio of 2.85, which is taken as the system’s design condition. The dual-evaporation temperature heating dehumidification mode shows superior performance compared with the conventional mode under typical winter conditions in three different climatic zones. Moreover, energy consumption can be reduced by reasonably controlling the operation mode based on ambient conditions. An operation strategy for the dual-evaporation temperature heat pump system in winter is proposed through the regional division of the psychrometric chart, and the energy-saving operation mode of the system is analyzed for different climate zones in China.

Perception of Selected Aspects of Online Learning by Czech Higher Education Students

The study is based on an analysis of real educational processes in the period 2020-2021, when the most significant pandemic waves of Covid-19 were recorded in the Czech Republic. In relation to this, the study aims to identify the views of 968 students on the changed conditions of education and the perception of selected aspects of the transition to online learning by respondents from two higher education institutions in the Czech Republic, the first of which is focused on humanities and the second specializes in economics studies. The research is aimed at discovering students’ attitudes towards the form of distance education forced on them by the relevant circumstances, the use of individual components of distance education to support teaching originally designed for the in-person form, the level and effectiveness of the use of information technologies in online learning and the potential of hybrid learning. For a greater degree of analyticity, a combined research model based on both quantitative and qualitative research has been chosen. Aspects of online learning that could be employed as complementary tools in the full-time conventional study mode have been identified. Students of economics can better visualize the inclusion of online learning in the full-time conventional study mode. Master level students are critical of online learning. The results have been used to design and empirically validate appropriate learning strategies with reflection on current student needs.

To tread or not to tread: comparison between water treading and conventional flapping wing kinematics

Hovering insects are limited by their physiology and need to rotate their wings at the end of each back-and-forth motion to keep the wing’s leading edge ahead of its trailing edge. The wing rotation at the end of each half-stroke pushes the leading edge vortex away from the wing which leads to a loss in the lift. Unlike biological fliers, human-engineered flapping wing micro air vehicles have different design limitations. They can be designed to avoid the end of stroke wing rotation and use so-called water-treading flapping kinematics. Flapping wings using conventional flapping kinematics have a designated leading and trailing edge. In the water-treading mode, the role of the leading and trailing edges are continuously alternated throughout the stroke. Here, we compare velocity field and force measurements for a rectangular flapping wing conducting normal hovering and water-treading kinematics to study the difference in fluid dynamic performance between the two types of flapping kinematics. We show that for similar power consumption, the water-treading mode produces more lift than the conventional hovering mode and is 50% more efficient for symmetric pitching kinematics. In the water-treading mode, the leading edge vortex from the previous stroke is not pushed away but is captured and keeps the newly formed leading edge vortex closer to the wing, leading to a more rapid increase of the lift coefficient which is sustained for longer. This makes the water-treading mode a promising alternative for human-engineered flapping wing vehicles.

Control of interaction force in constant-height contact mode atomic force microscopy

Contact mode is a versatile and widely used technique for imaging samples using the Atomic Force Microscope (AFM). When contact mode imaging is performed in constant-height mode, it enables linear and faster response but leads to uncontrolled tip-sample forces. Here, a control strategy based on magnetic actuation is proposed to achieve high-bandwidth control of the tip-sample forces in constant-height contact mode AFM. A magnetic particle attached to the AFM probe is actuated by an external solenoid and employed for force regulation. A quasi-static model has been proposed and employed to develop the control strategy. Likewise, the contact natural-frequency, which decides the limit of achievable speed, has been shown to be significantly higher relative to the free probe and to be relatively insensitive to the particle size. Subsequently, a setup is developed to validate the control strategy and demonstrate reduction of tip-sample force variation by over a factor of 12 compared to conventional constant-height mode operation. Likewise, in comparison with conventional contact mode AFM, an improvement of linearity by over a factor of 9 and improvement in response speed by a factor of 100 have been demonstrated while imaging hard samples. The system has been shown to image topography at speeds of 2.44 frames per second while regulating the interaction force. Finally, the stiffness of a sample has also been characterized using the developed system and simultaneous estimation of topography has also been demonstrated. They are shown to agree well with theoretical expectations.

High-Performance Solid Medium Thermal Energy Storage System for Heat Supply in Battery Electric Vehicles: Proof of Concept and Experimental Testing

The reduction of global CO2 emissions requires cross-sectoral measures to reduce fossil energy consumptions and to strengthen the expansion of renewable energy sources. One element for this purpose are thermal energy storage systems. They enable, due to their time-decoupled operation, increases in systemic efficiency and flexibility in various industrial and power plant processes. In the electricity and heat sector such solutions are already commercially available for large-scale applications or are focused in diverse R&amp;D projects, but are largely new in the transport sector. By transferring existing concepts specifically to the requirements for the heat supply of battery electric vehicles, efficiency improvements can also be achieved in the transport sector. The idea is to provide the required heat for the interior during cold seasons via a previously electrical heated thermal energy storage system. Thus, battery capacities can be saved, and the effective range of the vehicle can be increased. Basic prerequisites for this concept are high systemic storage densities and high performances, which must be justified to commercial battery powered PTC-elements. Compared to large-scale applications, this results in new challenges and design solutions needing finally a proof of concept and experimental tests under vehicle typical specifications. For the first time, a novel thermal energy storage system based on ceramic honeycombs with integrated heating wires and a double-walled, thermally insulated storage containment was developed and constructively realized. This storage system meets all the requirements for the heat supply, reaches high systemic storage and power densities and allows due to its high flexibility a bifunctional operation use: a cyclic storage and a conventional heating mode. In the focused storage operation, high-temperature heat is generated electrically through heating wires during the charging period and transferred efficiently via thermal radiation to the ceramic honeycombs. During the discharging period (driving) the stored thermal energy is used for heating the interior by a bypass control system at defined temperatures with high thermal output. The systematic measurement campaigns and successful model validations confirm high electrical heating powers of 6.8 kW during the charging period and a heat supply with a thermal output of 5 kW over more than 30 min during the discharging period. Despite current infrastructure and test rig restrictions, high systemic storage densities of 155 Wh/kg with constant discharging outlet temperatures are reached. Compared to battery powered heating systems, the experimental results for the developed thermal energy storage system confirm an excellent level of competitiveness due to its high performance, operational flexibility and low-cost materials.

Comparative assessment of di-ethyl ether/diesel blends on the performance, and emission characteristics in acetylene dual fuel engine

Many engine specialists have utilized various oxygenated blends such as methyl and ethyl esters, alcoholic fuels, and ether to boost the efficiency of dual fuel engine (DFE). However, there hasn’t been much study done to examine the effects of di-ethyl ether (DEE) in a gaseous fueled engine. Hence, in the present study, the author has examined the impact of the DEE/diesel mixture on the combustion, performance, and exhaust emissions in the acetylene-fueled customized engine. The acetylene is injected at 4 l/min (LPM) through the intake manifold while neat diesel, BD05, BD10, BD15, and BD20 blends are used as ignition sources at various engine loads. It is found that when the engine is operated with an ABD10 fuel combination the brake thermal efficiency (BTE) inclines by 1.7% as compared to standard diesel. The BTE is escalated due to an increased DEE proportion of up to 10% using BD10 pilot fuel at 80% load. However, further increasing the proportion of DEE results is a bit inferior in comparison to conventional diesel mode. Moreover, HC, CO, NOx, and smoke reduce considerably by 27%, 45%, 22%, and 43% respectively in comparison to neat diesel at 80% load while utilizing ABD10 fuel. This may be attributed to the superior physico-chemical properties of the pilot fuel blends permitting legitimate burning of the acetylene-air mixture. Additionally, it is also observed that consumption of neat diesel is decreased by 40% under high load using BD10 mixture as pilot fuel. Consequently, it is recommended to use DEE up to 10% with standard diesel in an acetylene-fueled engine for increasing BTE as well as to mitigate exhaust pollutants.

Effects of injection parameters on CRDI-equipped stationary diesel engine fuelled with neat biodiesel mix derived from waste feedstocks

This present work deals with the effects of injection parameters such as pilot-main injection mass ratio and dwell time on combustion, performance, and emission characteristics of a diesel engine. A single cylinder diesel engine is used in this research work with the flexibilities to modify different variables via open electronic control unit. Biodiesel mix (BDM) used in the present work is derived from waste feedstocks of used cooking oil and chicken fat. Throughout the experiment, engine load and speed were maintained constantly at 4.51 brake mean effective pressure and 1500 rpm, respectively. Different pilot mass ratios (10%, 20%, and 30%) and dwell times (20° crank angle (CA), 30° CA, and 40° CA) were tested and results were compared with conventional mode combustion. The results indicated that the pilot injections helped to reduce the ignition lag period and also shortened the combustion duration. The highest brake thermal efficiency of 34.78% was identified with the lowest pilot mass of 10%. According to the results, increased dwell time decreased the oxides of nitrogen emissions but increased the hydrocarbon emissions. The experiment revealed that BDM made of waste feedstocks could be an effective alternative for engine applications with optimized engine operating conditions.

Dynamic feature extraction and recognition of flow states in vaneless space of a prototype reversible pump turbine in generating mode based on variational mode decomposition and energy index

Dynamic feature extraction of pressure fluctuation signals and recognition of flow states in vaneless space have important engineering significances to guarantee the operational stability of the prototype reversible pump turbine (RPT) in the pumped hydro energy storage power station. In the present paper, in order to carry out accurate dynamic feature extraction of the flow states in the vaneless space, a method based on variational mode decomposition (VMD), energy index (EI) and support vector machine (SVM) is proposed. During the analysis procedure of pressure fluctuation signals, VMD can greatly avoid the mode mixing phenomenon, which often occurs in conventional empirical mode decomposition (EMD). After VMD analysis, several mode components with strong physical significances and separated central frequencies are obtained. Then, the EI of each mode component based on VMD is calculated and screened out. The EIs of the first three mode components are further constructed as the eigenvector that can accurately reflect different flow states in the vaneless space of the RPT. In addition, the intelligent classifier of SVM is employed to identify three types of flow states. The above eigenvectors can be employed as the input vectors of SVM. The average recognition results of 10 times show that the correct recognition rate of the proposed VMD-EI-SVM method (98.67 %) is higher than that of the EMD-EI-SVM method (88.00 %), which is more suitable for engineering applications.