Low Load Conditions Research Articles

Investigation of the effect of injection rate shaping on combustion and emissions in heavy-duty diesel engine under steady and transient conditions

The fuel injection rate (ROI) is a crucial factor that affects the combustion and emissions of diesel engines. This study focuses on the injection pressure in a common rail system, which is divided into a high-pressure section and a low-pressure section. A control-oriented ROI shaping (ROIs) model is developed based on the switching strategy between high and low injection pressure. Three types of ROI were generated, namely ROIB (conventional ROI), boot-ROI (low followed by high injection pressure), and anti-boot-ROI (high followed by low injection pressure) respectively. The 1-D and 3-D numerical simulations are conducted to analyze the impact of the shaped ROI on combustion and emissions for steady condition and transient condition. In terms of overall results, boot-ROI shows significant advantage among the three types of ROI. For the steady condition, the boot-ROI was able to increase the IMEP (indicated mean effective pressure) (1.57 bar) at high load conditions with almost unchanged NOx emission. For low load conditions with delayed SOI (start of injection), the exhaust temperature is close to that of the ROIB with a reduction of 0.51 g/kW·h in NOx emissions. For transient condition, the boot-ROI also shows its advantage. It was found to improve the BSFC (brake specific fuel consumption) with almost unchanged NOx emission during load-down process. And in load-up process, the BSFC and soot emission also could be improved with slightly increase in NOx emission through advance of SOI when boot-ROI was adopted. The one-dimensional model using boot-ROI reduces fuel consumption by 2 g/kW·h in experiment with WHTC cycles, with slightly higher soot emission and similar NOx emission.

Aerosol influence on cloud macrophysical and microphysical properties over the Tibetan Plateau and its adjacent regions.

This study uses aerosol optical depth (AOD) and cloud properties data to investigate the influence of aerosol on the cloud properties over the Tibetan Plateau and its adjacent regions. The study regions are divided as the western part of the Tibetan Plateau (WTP), the Indo-Gangetic Plain (IGP), and the Sichuan Basin (SCB). All three regions show significant cloud effects under low aerosol loading conditions. In WTP, under low aerosol loading conditions, the effective radius of liquid cloud particles (LREF) decreases with the increase of aerosol loading, while the effective radius of ice cloud particles (IREF) and cloud top height (CTH) increase during the cold season. Increased aerosol loading might inhibit the development of warm rain processes, transporting more cloud droplets above the freezing level and promoting ice cloud development. During the warm season, under low aerosol loading conditions, both the cloud microphysical (LREF and IREF) and macrophysical (cloud top height and cloud fraction) properties increase with the increase of aerosol loading, likely due to higher dust aerosol concentration in this region. In IGP, both LREF and IREF increase with the increase in aerosol loading during the cold season. In SCB, LREF increases with the increase in aerosol loading, while IREF decreases, possibly due to the higher hygroscopic aerosol concentration in the SCB during the cold season. Meteorological conditions also modulate the aerosol-cloud interaction. Under different convective available potential energy (CAPE) and relative humidity (RH) conditions, the influence of aerosol on clouds varies in the three regions. Under low CAPE and RH conditions, the relationship between LREF and aerosol in both the cold and warm seasons is opposite in the WTP: LREF decreases with the increase of aerosol in the cold season, while it increases in the warm season. This discrepancy may be attributed to a difference in the moisture condition between the cold and warm seasons in this region. In general, the influence of aerosols on cloud properties in TP and its adjacent regions is characterized by significant nonlinearity and spatial variability, which is likely related to the differences in aerosol types and meteorological conditions between different regions.

Acute hypoalgesic, neurophysiological and perceptual responses to low-load blood flow restriction exercise and high-load resistance exercise.

This study compared the acute hypoalgesic and neurophysiological responses to low-load resistance exercise with and without blood flow restriction (BFR), and free-flow, high-load exercise. Participants performed four experimental conditions where they completed baseline measures of pain pressure threshold (PPT), maximum voluntary force (MVF) with peripheral nerve stimulation to determine central and peripheral fatigue. Corticospinal excitability (CSE), corticospinal inhibition and short interval intracortical inhibition (SICI) were estimated with transcranial magnetic stimulation. Participants then performed low-load leg press exercise at 30% of one-repetition maximum (LL); low-load leg press with BFR at 40% (BFR40) or 80% (BFR80) of limb occlusion pressure; or high-load leg press of four sets of 10 repetitions at 70% one-repetition maximum (HL). Measurements were repeated at 5, 45min and 24h post-exercise. There were no differences in CSE or SICI between conditions (all P>0.05); however, corticospinal inhibition was reduced to a greater extent (11%-14%) in all low-load conditions compared to HL (P<0.005). PPTs were 12%-16% greater at 5min post-exercise in BFR40, BFR80 and HL compared to LL (P≤0.016). Neuromuscular fatigue displayed no clear difference in the magnitude or time course between conditions (all P>0.05). In summary, low-load BFR resistance exercise does not induce different acute neurophysiological responses to low-load, free-flow exercise but it does promote a greater degree of hypoalgesia and reduces corticospinal inhibition more than high-load exercise, making it a useful rehabilitation tool. The changes in neurophysiology following exercise were not related to changes in PPT.

Satellite-Based Background Aerosol Optical Depth Determination via Global Statistical Analysis of Multiple Lognormal Distribution

Determining background aerosol optical depth threshold value (BAOD) is critical to aerosol type identification and air pollution control. This study presents a statistical method to select the best BAOD threshold value using the VIIRS DB AOD products at 1 × 1 degree resolution from 2012 to 2019 as a major testbed. A series of multiple lognormal distributions with 1 to 5 peaks are firstly applied to fit the AOD histogram at each grid point, and the distribution with the highest correlation coefficient (R) gives preliminary estimations of BAOD, which is defined as either the intersection point of the first two normal distribution curves when having multiple peaks, or the midpoint between the peak AOD and the first AOD with non-zero probability when the mono peak is the best fit. Then, the lowest 1st to 100th percentile AOD distributions are compared with the preliminary BAOD distribution on a global scale. The final BAOD is obtained from the best cutoff percentile AOD distributions with the lowest bias compared with preliminary BAOD. Results show that the lowest 30th percentile AOD is the best estimation of BAOD for different AOD datasets and different seasons. Analysis of aerosol chemical information from MERRA-2 further supports this selection. Based on the BAOD, we updated the VIIRS aerosol type classification scheme, and the results show that the updated scheme is able to achieve reliable detection of aerosol type change in low aerosol loading conditions.

Comparison of the transient response of a compression ignition engine running with gasoline, naphtha, and methanol as fuels

This study conducted a detailed investigation to evaluate the transient operation of a compression ignition engine using three low-reactivity fuels. The fuels tested were gasoline, methanol, and naphtha. This research gives valuable insight into how these alternative fuels behave under dynamic operating conditions compared to stationary conditions. Employing a comprehensive two-part methodology, the study firstly undertakes experimental procedures involving parametric sweeps to optimize the engine performance across three operating conditions, and a dedicated calibration was achieved for the engine operation for each of the three fuels. With this calibration, two transient cycles were proposed for evaluating the engine response regarding the injection system, air management system, and emissions. The transient response was assessed through load variations at fixed engine speeds and combined cycles of speed and load transitions. The second part of the work covered a numerical assessment using GT-Power to simulate global emissions in a Class 3 WLTC. The findings reveal that naphtha outperforms other LRFs like methanol and gasoline in torque response and stability in fixed-speed cycles. Methanol, while exhibiting almost negligible soot emissions, encountered significant combustion stability challenges under low-load conditions, rendering it less suitable for exclusive use in real vehicle scenarios. On the other hand, naphtha showed promising results as a diesel alternative in the WLTP cycle, achieving similar torque and speeds, with a substantial reduction of 40 % in NOx emissions, a slight increase of 9 % in soot emissions, and an important reduction of 10 g CO2/km in carbon impact. However, the rise in unburned hydrocarbon species poses a challenge for meeting tailpipe emissions regulations.

Modeling and analysis of 3D mixed lubrication in marine cam–tappet pair

During the operation of the marine cam–tappet pair, affected by periodic dynamic load, transient velocity, and micromorphology, it usually operates in a mixed lubrication state. Under extreme operational conditions, contact is likely to occur at the asperity of the interface, leading to problems such as stress concentration and dry contact. Considering the transient dynamics and three-dimensional roughness of cam–tappet pair, a mixed-elastohydrodynamic lubrication model is developed in this article, while the effects of surface waviness on the lubrication state are also investigated. The results show that the film thickness can be increased by 0.098 μm, and the coefficient of friction can be reduced by 10.6% when the wavelength ratio ranges from 1/6 to 6. However, when the amplitude exceeds 0.6 μm, the coefficient of friction may reach 0.10. Under conditions of low speed and high load, the film thickness decreases and contact load ratio increases. And about 30% reduction in film thickness is achieved on cam–tappet pair, potentially leading to increased wear or scuffing failure.

Effects of natural gas admission location and timing on performance and emissions characteristics of LPDF two-stroke engine at low load

Low-pressure gas-admission marine two-stroke engines have significant potential for reducing emissions in the shipping industry. However, they exhibit poor combustion quality under low-load conditions, leading to lower thermal efficiency and high levels of HC and CO emissions. This study numerically evaluated the impacts of the gas admission location and timing on engine performance and exhaust gas emissions under low load conditions. The study revealed that different gas admission locations form distinct NG-air stratifications. Lower gas admission locations resulted in longer ignition delays and shorter combustion durations. The unburned CH4 and CO emissions were significantly reduced by a maximum of 20.14% and 42.29%, respectively. A trade-off exists between NOx and N2O emissions owing to the different temperature conditions of their formation. The NOx emissions increased continuously as the gas admission location was lowered to a maximum of 3.4218 g/kWh; a value slightly above the Tier III emission standards. Advancing the timing of gas admission further decreased the ignition delay time, NOx, and unburned CH4 emissions. This study revealed that in-cylinder natural gas mixture stratification due to varying gas admission locations and timings can improve the combustion efficiency and exhaust gas emissions of a natural gas-diesel dual-fuel engine under low-load conditions.

Optimization of methanol/diesel dual-fuel engines at low load condition for heavy-duty vehicles to operated at high substitution ratio by using single-hole injector for direct injection of methanol

Methanol, as a low-carbon and easily synthesizable fuel, is one of the promising directions for future internal combustion engine (ICE) fuels. However, methanol/diesel engines with high energy substitution ratios exhibit a significant drawback at low loads, namely poor fuel economy, which seriously hinders the development of dual fuel engines. Therefore, this paper conducts an optimization study on the combustion strategy of methanol/diesel in heavy-duty vehicle engines under high energy substitution ratios (70 %) and low loads. Innovatively combines single-hole injection with the direct dual fuel stratification (DDFS) technology. By coupling the longer injection duration of a single hole with higher injection pressure, and tailored combustion strategy adjustments, successfully achieving the goal of optimizing low-load methanol dual fuel engines. The research results indicate that when employing a methanol single-stage injection strategy, setting the start of diesel injection (SODI) of −25°CA after top dead center (ATDC) effectively enhances the combustion efficiency of methanol/diesel, especially when combined with a strategy that the start methanol injection (SOMI) is of −23°CA ATDC. This combination can boost the gross indicated thermal efficiency (ITEg) to 51.95 %. The research on utilizing a methanol two-stage injection strategy found that increasing the methanol premixing appropriately, within the engine's safe range, can effectively enhance ITEg. Specifically, with the methanol pre-injection ratio (MPR) of 10 % and the methanol two-stage injection interval (MII) of 20°CA, ITEg can be improved to 52.07 %. However, excessively of premixing can lead to premature combustion, causing an increase in negative work during the compression stroke and consequently reducing ITEg. This study has unveiled effective solutions for the application of methanol/diesel DDFS technology in the automotive engine field. It offers insights into the selection and optimization of methanol injectors and provides theoretical support and practical references for achieving clean and efficient combustion in engines.

Performance and carbon emissions of a diesel/oxy-hydrogen dual-fuel engine with oxy-hydrogen injection variation under low and medium load conditions

Reducing carbon emissions such as carbon dioxide (CO2) and carbon monoxide (CO) from diesel engines struggled with engine performance challenges and fossil fuel limitations. Besides, huge transportation such as ships hardly replaced diesel engines due to the higher thermal efficiency and low operation cost. Oxy-hydrogen gas, as a carbon-free gas, could potentially improve diesel engine performance and carbon emissions. Most of the studies tried to identify the effect of oxy-hydrogen induction into diesel engine combustion on performance and emissions. However, this study evaluated oxy-hydrogen injector sizes to the diesel engine performance and carbon emissions at several loads and several engine speed conditions. Overall, the result showed that the oxy-hydrogen gas injection into the diesel engine’s intake port improved the performance and carbon emissions compared to the single diesel fuel as a baseline. High engine performance with low carbon emissions could be achieved at low and medium engine load conditions with high engine speeds. Moreover, smaller oxy-hydrogen injector sizes were suitable for the medium engine load and vice versa, to improve the performance and carbon emissions. At low load, the engine performance improvement of engine torque, specific fuel consumption, and thermal efficiency were 1800 to 2200 rpm. Moreover, the CO2 and CO emissions reductions were also suitable with 2200 rpm with a bigger oxy-hydrogen gas injector (6 mm). Furthermore, at medium load, the engine performance improved at 1400 rpm but the CO2 and CO emissions were lower at 2200 rpm with a small oxy-hydrogen gas injector (4 mm). The engine operation at 2200 rpm with a 4 mm injector also improved the engine performance regarding carbon emissions reduction. However, injecting oxy-hydrogen gas into diesel engines had the potential to enhance the engine performance and reduce carbon emissions, moving closer to achieving zero emissions

Working memory load impairs tacit coordination but not inter-brain EEG synchronization.

Coordinating actions with others is thought to require Theory of Mind (ToM): the ability to take perspective by attributing underlying intentions and beliefs to observed behavior. However, researchers have yet to establish a causal role for specific cognitive processes in coordinated action. Since working memory load impairs ToM in single-participant paradigms, we tested whether load manipulation affects two-person coordination. We used EEG to measure P3, an assessment of working memory encoding, as well as inter-brain synchronization (IBS), which is thought to capture mutual adjustment of behavior and mental states during coordinated action. In a computerized coordination task, dyads were presented with novel abstract images and tried selecting the same image, with selections shown at the end of each trial. High working memory load was implemented by a concurrent n-back task. Compared with a low-load control condition, high load significantly diminished coordination performance and P3 amplitude. A significant relationship between P3 and performance was found. Load did not affect IBS, nor did IBS affect performance. These findings suggest a causal role for working memory in two-person coordination, adding to a growing body of evidence challenging earlier claims that social alignment is domain-specific and does not require executive control in adults.

Revealing the reaction regularity of Mn-CeO2-x catalyst system in catalytic filter for low-temperature NH3-SCR

A series of manganese-cerium-based (MnO2-CeO2-x) polyphenylene sulfide (PPS) catalytic filters were prepared via a redox method to enhance catalytic activity and physico-chemical performances. The oxidation regularity of the cerous ion (Ce3+) was revealed through controlling KMnO4 content, based on which a Mn-Ce catalyst system and its corresponding redox equation were established. Furthermore, the preparation of the optimal catalytic filter achieved satisfactory catalytic performance compared with the previous catalytic filters (NO conversion of 93.5 % at 180 °C under low load conditions). This catalytic filter also exhibits excellent catalyst stability, gas permeability, bonding strength, and mechanical properties, making it suitable for complex operating conditions. Particularly, the coexistence of CeO2 and Ce2O3 in the catalyst system leads to an imbalance in surface charge, oxygen vacancies, and unsaturated chemical bonds on the surface of the catalyst, thereby increasing the amount of chemisorbed oxygen, promoting NO oxidation, and further improving selective catalytic reduction of NOx with NH3 (NH3-SCR).

Effects of Varying Equivalence Ratios on the Combustion Efficiency Characteristic of a Dual-Fuel Compression Ignition Engine by Changing Intake Pressures and Exhaust Gas Recirculation Rates

In general, a leaner mixture condition improves combustion efficiency in compression ignition (CI) combustion using diesel. However, in the case of leaner air–fuel mixture conditions, it disturbs flame propagation in spark ignition combustion using gasoline, i.e., low reactivity fuel, causing a decrease in combustion efficiency. Since dual-fuel combustion in a CI engine typically involves the use of high- and low-reactivity fuels together, the differing reactivity conditions in the cylinder become as important as the local equivalence ratio in the cylinder. Thus, there is a need to verify the effect of a leaner mixture condition on combustion efficiency in dual-fuel CI combustion. For this reason, this study experimentally evaluates the effects of varying equivalence ratios on the combustion efficiency of gasoline/diesel dual-fueled CI combustion in a 0.4-L single-cylinder engine under low-speed (1500 rpm) and low-load (total LHV 570 J/str) conditions. To vary the equivalence ratios, intake pressures and exhaust gas recirculation (EGR) rates were, respectively, changed under the part-load condition. The results emphasize that as the equivalence ratio becomes leaner by increasing the intake pressure, combustion efficiency worsens due to the low reactivity properties and certain flame propagation modes of gasoline combustion. On the contrary, increasing the EGR rate did not significantly influence combustion efficiency, but it effectively helped reduce nitrogen oxide (NOx) emissions. Based on these results, it is concluded that optimizing dual-fuel CI combustion to suppress NOx emissions is better achieved using EGR, rather than creating a leaner mixture condition.

Dynamic accelerated stress test and coupled on-line analysis program to elucidate aging processes in proton exchange membrane fuel cells

The application of hydrogen proton exchange membrane fuel cells (PEMFC) in greenhouse gas emission free heavy-duty vehicles requires extremely durable PEMFC components with service lives in the range of 30,000 h. Hence suitable test and analysis methods are required that reflect realistic operation scenarios, but significantly accelerate aging. For this purpose, a dynamic accelerated stress test was developed, which is coupled with a comprehensive in-depth in-situ and ex-situ analysis program to determine the aging processes of a PEMFC membrane electrode assembly (MEA). The test comprehends dynamic cycling between low, moderate and high load, different temperature and humidity conditions as well as recovery sequences to distinguish between reversible and irreversible failure modes. All phases of the PEMFC system (i.e. solid, liquid and gaseous) are monitored on-line during aging by sophisticated electrochemical, mass spectrometric and ion chromatographic analytical methods. The structural and elemental composition of the MEA before and after the aging program (post-mortem) are investigated by X-ray fluorescence, scanning and transmission electron microscopy. This program was able to age a commercial PEMFC to end-of-life in 1000 h, while providing an accurate picture of the aging processes involved.

Mental imagery scaffolding: The effects of detail richness and text load on geography learning

The growing importance of 3D animations in current teaching approaches becomes increasingly apparent, offering an effective way to visualize complex spatial concepts and processes in geography learning through outstanding visual representation and details. However, the effects of detail richness and text load of 3D animation on learning about processes remain unclear. Addressing this research gap, the present study adopts a quasi-experimental design involving four classes (n = 106) in the context of a geography lesson and evaluates four conditions in a 2 × 2 between-subjects design consisting of detail richness (high vs. low) and text load (high vs. low). The lessons on the rotation and revolution of the Earth were delivered by the same instructor across all conditions. Knowledge acquisition, cognitive load, learning experience, and emotions of students were measured. The results revealed that students were significantly better able to acquire knowledge immediately when exposed to the high detailed visuals but low text load condition. Low detail richness and high text load independently resulted in increased cognitive load. We also observed a significant effect of detail richness on the dimensions of pleasure and arousal, with higher levels of details associated with larger values in these dimensions. This research suggests that when the learning objective necessitates the engagement of mental imagery, incorporating detailed visuals can facilitate learning. The findings contribute to our understanding of how detailed imagery is linked to learning objectives about processes and expand our knowledge regarding the design of detail richness and text of 3D animation in the context of geography learning.

An Economic Analysis of Energy Saving and Carbon Mitigation by the Use of Phase Change Materials for Cool Energy Storage for an Air Conditioning System—A Case Study

Phase change materials are increasingly used because they can be used for cold energy storage in air conditioning systems to increase system efficiency and achieve energy savings. However, many potential adopters of phase change cold storage systems fail to consider environmental and economic factors, so feasibility assessments are difficult and significant gaps between expected benefits and actual outcomes become apparent. This study establishes an economic analysis model using a technology company in Taiwan as an example. The model determines the costs and energy-saving carbon reduction benefits of implementing phase change materials to allow businesses to achieve energy-saving, carbon reduction, and sustainable development objectives. The results of this study demonstrate that companies can achieve a 32% reduction in electricity costs, reduce energy consumption by 118,411 kWh per year, and reduce carbon emissions by 60,272 tons per year by adopting phase change materials. The dynamic payback period is as little as 2.9 years for low-load conditions. A cost–benefit analysis also shows that the use of phase change materials for energy storage, coupled with the prior construction of energy storage areas, provides the maximum economic benefits and is the optimal choice.

Mesh stiffness modeling and dynamic simulation of spur gears with body crack under speed fluctuation condition

The traditional method for calculating the time-varying mesh stiffness (TVMS) of cracked gears usually assumes that the root crack is solely located within the gear tooth. Accurate calculation becomes a challenge when the crack propagates into the gear body. In this paper, an improved model for calculating the TVMS of spur gears with crack propagation into the gear body is proposed based on a combined analytical finite element-potential energy method, and the accuracy of the proposed model is verified by the finite element method. A 5-degree-of-freedom (5-DOF) dynamic model with speed fluctuation is developed, taking into account the coupling shaft-bearing stiffness as the support stiffness. Subsequently, a dynamic simulation of a gear system with a gear body crack is conducted. The results indicate that the proposed analytical model can provide relatively accurate mesh stiffness for crack propagation into the gear body. The TVMS decreases as the crack length increases, the decrease in mesh stiffness becomes more significant when considering the influence of the crack on the gear body stiffness. The dynamic response obtained from the proposed dynamic model shows more pronounced pulse characteristics compared to the model that does not consider the influence of shaft stiffness. The low speed and heavy load conditions restrain the speed fluctuation of the gear system. The residual signal is more effective for identifying fault signals than the original signal. The proposed model can provide theoretical and methodological references for diagnosing faults in gear systems with crack propagation into the gear body.

Influence of Perceptual Load on Attentional Orienting in Post-Stroke Fatigue: A Study of Auditory Evoked Potentials

Objective Increasing perceptual load alters behavioral outcomes in post-stroke fatigue (PSF). While the effect of perceptual load on top-down attentional processing is known, here we investigate if increasing perceptual load modulates bottom-up attentional processing in a fatigue dependent manner. Methods In this cross-sectional observational study, in 29 first-time stroke survivors with no clinical depression, an auditory oddball task consisting of target, standard, and novel tones was performed in conditions of low and high perceptual load. Electroencephalography was used to measure auditory evoked potentials. Perceived effort was rated using the visual analog scale at regular intervals during the experiment. Fatigue was measured using the fatigue severity scale. The effect of fatigue and perceptual load on behavior (response time, accuracy, and effort rating) and auditory evoked potentials (amplitude and latency) was examined using mixed model ananlysis of variances (ANOVA). Results Response time was prolonged with greater perceptual load and fatigue. There was no effect of load or fatigue on accuracy. Greater effort was reported with higher perceptual load both in high and low fatigue. p300a amplitude of auditory evoked potentials (AEP) for novel stimuli was attenuated in high fatigue with increasing load when compared to low fatigue. Latency of p300a was longer in low fatigue with increasing load when compared to high fatigue. There were no effects on p300b components, with smaller N100 in high load conditions. Interpretation High fatigue specific modulation of p300a component of AEP with increasing load is indicative of distractor driven alteration in orienting response, suggestive of compromise in bottom-up selective attention in PSF.

The effect of verbal praise on prospective memory.

Verbal praise is often used to improve prospective memory performance in daily life. According to the motivation cognitive model, the promotional effect of verbal praise on prospective memory may depend largely on redeploying attentional resources, so its promotional effect is likely to be influenced by attention. Two groups of college students (n = 128, n = 117) participated in two experimental studies that examined this hypothesis. Experiment 1 manipulated attention load by changing the difficulty of the ongoing tasks to focus on the effect of verbal praise on prospective memory under different attention load conditions. The results showed that verbal praise promoted prospective memory performance under both attentional load conditions (low, high), but verbal praise mainly promoted the prospective component when the attentional load was low, meanwhile, verbal praise mainly promoted the retrospective component when the attention load was high. Experiment 2 altered the dependence of prospective memory tasks on attentional resources by manipulating the cue focality, further exploring the promotional effect of verbal praise on prospective memory with different types of cues under the low attention load condition. The results showed that verbal praise only promoted prospective memory when non-focal cues were used. The results of this study partially verified the motivation cognitive model.

Using narrative 360° video as a tool to promote breast self-examination

This experiment examined the feasibility of 360° video as a tool for public health messaging by investigating the effect that viewing the 360° documentary The Waiting Room VR had on female viewers’ sense of identification, attitudes to breast cancer screening and mortality salience. A key part of the documentary places participants in a viewpoint ambiguously aligned to that of the film’s director and subject, Victoria Mapplebeck (VM), in a scene that recreates her radiotherapy treatment for breast cancer. Eighty female participants watched the documentary either sitting upright with the chair back set at a 90° angle or reclining with the chair back set at a 140° angle (consistent with VMs posture) under conditions of either high or low cognitive load. The effect of posture type was measured explicitly using questionnaires on presence, identification and breast self-examination (BSE) intention as well as implicitly using a lexical decision task to measure death-thought awareness (DTA). Reclined posture led to a higher sense of spatial presence but no increase in identification with VM. Significantly increased identification with VM led to greater intention to conduct BSE. There were no effects of posture, cognitive load or identification on DTA. The implications of these results for using 360° video as a behaviour change tool, the effects of the COVID-19 pandemic on the terror management manipulation and the relevance of spatial viewpoint in 360° video are discussed.

Compensation of Discontinuous Conduction in Three Phase Voltage Source PWM Inverters

Nowadays the increasing utilization of alternative energy sources demand power converters capable of delivering high quality energy to the low voltage grid. Good dead time compensation and linear operation are essential to keep low order harmonics at acceptable levels. High-current operating conditions are well handled by traditional methods, but low current behaviour and waveforms with multiple zero crossings within a switching period are problematic, especially at low load conditions at or below 10% load. Such conditions often occur in the battery chargers of electric cars. Power quality is also essential for sensorless drives, as the accuracy of the output voltage is very important especially at low rotational speeds. This paper describes the identified cases of discontinuous conduction during dead time. Based on the voltage and current waveforms of the three phase inverter, an improved dead time compensation method is shown for symmetric PWM controlled inverters. The compensator uses already available measurement data, and compensates the resulting error voltage at duty cycle level. The described method can be used for any type of three phase modulation. A similar approach can also be used for two phase modulations.