Low Load Conditions Research Articles

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.

Optimizing combustion and emissions in natural gas/diesel dual-fuel engine with pilot injection strategy

For the clean and efficient operation of agricultural power, a non-road common-rail engine was modified to achieve natural gas/diesel dual-fuel (NDDF) combustion mode. Under low load conditions, NDDF combustion deteriorates and fuel economy decreases due to lower pressure and temperature inside the cylinder. Therefore, effects of injection pressure, pilot injection timing (SOIpilot) and pilot injection quantity (Qpilot) on in-cylinder combustion, emission characteristics and fuel economy of NDDF engine with pilot injection strategy were investigated at low load. Results show that with the increment of injection pressure, the diesel fuel beam penetration distance increased, prompting the diesel more quickly and fully mixed with fresh charge. The maximum in-cylinder pressure increased, the combustion center (CA50) moved forward, the ignition delay period was shortened, and soot, HC, C2H4 and C3H6 emissions were reduced, while BTE was improved. When SOIpilot moved forward, the pilot injected diesel and natural gas were more fully mixed, which promoted the generation of activation radicals and combustion intensity of main injected diesel. Pmax first increased and then decreased, the peak value of first heat release rate (HRRP1) gradually decreased, the peak value of second heat release rate (HRRP2) continuously increased, the combustion duration decreased, and the soot, CO and HC emissions decreased. At SOIpilot = −30 °CA ATDC, unregulated emissions reached the lowest level, while BTE was 35.55 %. With the increment of Qpilot, both Pmax and HRRP1 increased, CA05 and CA50 moved forward, combustion duration was extended, COV decreased significantly, and all emissions except NOx decreased, especially aldehyde emissions.

Intelligent energy management of Microgrids with flexible demand response

This paper deals with the application of a mixed integer distributed ant colony optimization (MIDACO) algorithm as an energy management system for a microgrid represented by real time values and characteristics. The microgrid consisting of numerous sources of renewable energy such as solar photovoltaics, small hydro power plant and battery storage is also able to manage demand response in an intelligent manner so as to reduce the dependency on the utility grid during high peak conditions and also export power to the grid during lower load conditions.

Storage interference in working memory cannot be removed by attention

In the present study, we examined the hypothesis that the storage interference in working memory can be removed by attention. A dual-task paradigm was employed in Experiment 1 and 2, in which participants performed a color memory task and an RSVP letter detection task concurrently. The cognitive load of the RSVP letter detection task and the storage interference caused by the RSVP letter detection task was manipulated independently. That is, the produced storage-interference difference between the low and high interference conditions was comparable between the low and high cognitive load conditions, whereas the available attentional resources were different under the two cognitive load conditions. Since there were more attentional resources in the low load condition, the removal hypothesis predicts that differences in recall performance between the low and high interference conditions should be larger in high load than in low load, i.e., there would be an interaction between load and interference. However, the results of the two experiments did not show such an interaction. In Experiment 3, we manipulated the time available for the removal mechanism to work while inducing both the storage interference and processing interference. The results showed no sign of interference removal. Thus, the present results provided solid evidence to challenge the removal hypothesis.

Experimental investigation of operating conditions on performance and emissions of spark ignition ammonia direct injection engine

Hydrogen, attracting attention as a future eco-friendly fuel, is difficult to handle and store because of its material characteristics; thus, ammonia has been proposed as an alternative. However, when only ammonia is utilized as the fuel, the operating range in which stable combustion is possible is limited because of the slow combustion speed and high minimum ignition energy. Here, to examine the applicability of ammonia as an engine fuel, an experiment was conducted based on changes in hydrogen energy ratios and operating conditions in a direct-injection ammonia combustion engine with hydrogen addition. The hydrogen energy ratio for stable operation is about 4.5 % at 1500 rpm under low-load operating conditions such as BMEP 0.2 MPa, and hydrogen must be supplied at a high energy ratio of 27.8 % in the case of a rated-power condition of 3800 rpm. The unburned NH3 and NOx emissions were high at 9285 ppm and 4870 ppm, respectively, under rated-power operating conditions.

Applying SMART-Based Power Gating Approach in NoC System

SMART is a low-latency solution that transmits nonconflicting flits to remote routers, enabling traversal of multi-hop paths within a single cycle. It reduces packet latency but ignores high power consumption in idle components. Additionally, SMART’s low latency is highly dependent on [Formula: see text], which represents the maximum number of hops traversed within a cycle. Therefore, this paper presents SMART-PG, a power gating method based on SMART that reduces network power consumption by shutting down idle components such as router buffers under low-load conditions. We also extend the router architecture to enable the continuous establishment of single-cycle multi-hop bypass paths. Compared to SMART routers, our method eliminates packet buffering even when a packet reaches the last router of a single-cycle multi-hop path, reducing packet latency and sensitivity to [Formula: see text]. Finally, we propose a routing algorithm that enables efficient packet transmission in one-dimensional and two-dimensional networks even when routers are powered off. Experimental results show that our method reduces packet latency and static power consumption by an average of 7.5% and 46.4%, respectively, compared to the baseline router. Compared to SMART routers, our method demonstrates significant superiority in terms of packet latency and the impact of multi-hop length on packet latency.

Application of EMI technique in crack propagation under the block loading conditions for AA6061 alloy

The behaviour of a component under real/random loading conditions can be studied by converting the random load into block load. Therefore, knowledge of the initiation and propagation of a crack under block loading conditions is very important for the safety and reliability of machine components / structures. Electromechanical impedance (EMI) is a real-time damage evaluation technique in which simultaneous use of the high-frequency mechanical excitations and responses of the structure are made by employing a piezoelectric transducer. In the present study, an experimental methodology to monitor fatigue crack initiation and propagation under block loading conditions for AA6061 aluminium alloy has been studied with the help of the EMI technique. The piezoelectric sensor bonded on the Compact Tension (CT) specimen acts as an actuator and sensor both. The conductance signature provided a sufficient information about the damage and crack growth under high low and low high block loading conditions. The conventional crack growth rate versus range of stress intensity factor plot matches well with the crack growth rate versus shift in resonant frequency.

Comparison of Computed Tomography and Clinical Features Between Patients Infected with the SARS-CoV-2 Omicron Variant and the Original Strain.

To investigate potential differences in clinical and computed tomography (CT) features between patients with the SARS-CoV-2 Omicron variant and the original strain. This retrospective study included 69 hospitalized patients infected with Omicron variant from November to December 2022, and 96 hospitalized patients infected with the original strain from February to March 2020 in Chongqing, China. The clinical features, CT manifestations, degrees of lung involvement in different stages on CT, and imaging changes after the reverse-transcription polymerase chain reaction (RT-PCR) results turned negative were compared between the two groups. For clinical features, patients with Omicron were predominantly old people and females, without manifestation of any clinical symptoms, who had low serum levels of C-reactive protein and procalcitonin. Shorter interval from symptoms onset to initial CT scan was observed in Omicron patients compared to patients with the original strain (all P < 0.05). For CT features, patients with Omicron were more likely to present with round-like opacities and tree-in-bud pattern (all P < 0.05), but less likely to exhibit a diffuse distribution, patchy and linear opacities, as well as vascular enlargement pattern (all P < 0.05). The Omicron group was more susceptible to exhibiting lower CT involvement scores in each stage (all P < 0.05) and imaging progression after the RT-PCR results turned negative (P < 0.001). Patients infected with the Omicron variant exhibited less severe changes on chest CT compared to those infected with the original strain. Furthermore, imaging progression under low viral load conditions was more common in patients with Omicron than in those with the original strain.

Transient Characteristics and Performance of a Dual Compensation Chamber Loop Heat Pipe under Various Heat Loads

The dual compensation chamber loop heat pipe (DCCLHP) technology shows great promise for efficient thermal management in a variety of applications. This study focuses on refining the startup performance of the DCCLHP, particularly for low heat load conditions in terrestrial settings, by utilizing dual bayonet tubes. Empirical investigations examined the DCCLHP’s operational characteristics and improved thermal transfer capabilities across different orientations of the evaporator and compensation chamber (CC), including vertical, 45‐degree tilt angle, and horizontal configurations. Key results demonstrate the DCCLHP’s ability to manage low heat loads across diverse orientations, achieving over 400 W of heat transfer across a distance of 2.0 m while maintaining stable operation. Notably, the DCCLHP operation did not exhibit any significant instability issues. This work enhances the startup performance of the DCCLHP in various orientations and provides valuable insights into the confined natural circulation phenomenon, crucial for improving the overall thermal management capabilities of the system. In summary, the study highlights advancements in DCCLHP design and its potential to address thermal management challenges in diverse applications, particularly in the aerospace industry, through improved startup performance and enhanced heat transfer capabilities.

Experimental investigations on emission characteristics of heavy-duty hybrid electric vehicles

The emission characteristics under different operating modes (engine mode and hybrid mode) and different test cycles (C-WTVC and CHTC) of a heavy-duty hybrid electric dump truck was investigated on the chassis dynamometer. The emission performance was recorded using Portable Emissions Measurement System (PEMS) and analyzed combined with the characteristic parameters of the test conditions. It is found that the NOx emission under hybrid mode is higher than that under engine mode, while the CO emission under hybrid mode is lower than engine mode. Under engine mode, the NOx emission of CHTC is higher than that of C-WTVC. However, under hybrid mode, the NOx emission of CHTC is lower than C-WTVC. Analysis of CO emission characteristics shows that under engine mode, CO emission is concentrated at low speed and small load condition, while under hybrid mode, CO emission is concentrated at high speed and large load condition.

Dry sand abrasion characteristics of WC-10Ni+NiCrBSi coatings

A WC-10Ni/NiCrBSi coating was prepared and applied to the surface of Q235 steel through vacuum brazing. Using a self-developed dry sand abrasion test machine, the effects of the abrasive sand’s type, load, and sliding speed on the dry sand abrasion property of the coating were analysed. The wear mechanism of dry sand abrasion was also investigated. The results indicated that the coating cross-section comprised three layers: the substrate, the interface layer, and the surface layer. The hard layer served as the main distribution area of WC hard particles, which directly determined the hardness and wear resistance of the coating. WC particles, fortified by a γ-Ni solid solution, enhanced the wear resistance and hardness of the coating. In the friction and wear test, when ceramic abrasives were employed, the coating sample exhibited a loss of only 23 mg, constituting only 7.9% of that observed with quartz sand abrasives. Under low loading conditions, the wear mass loss exhibited a linear relationship with the applied load. During these low-load scenarios, the abrasive particles operated through a rolling motion, thereby entailing an abrasive wear mechanism. Conversely, when the load exceeded 0.05 MPa, the primary mode of abrasive particle motion transitioned into sliding with burial, resulting in a combination of fatigue wear and abrasive wear mechanisms. Therefore, the dry sand abrasion mechanism inherent to composite coatings can be attributed to the protective shielding role played by WC particles on the substrate. This shielding function effectively mitigates and counteracts the abrasive cutting effects induced by abrasive particles.

Effects of Injection Parameters and EHN Mixing on the Combustion Characteristics of Fueling Pure Methanol in a Compression Ignition Engine

As one of the most ideal alternative fuels for internal combustion engines, methanol can achieve near-zero carbon emissions. The main problem of methanol application in compression combustion engines is the phase lag caused by its poor combustion characteristics, but under low load conditions, the fuel activity can be improved by adding the cetane number improver EHN (Isooctyl nitrate), and the dependence on intake heating can be reduced to a certain extent. Based on a three-dimensional CFD simulation, the effects of methanol injection parameters and the addition of EHN on the combustion characteristics of a four-stroke exhaust turbocharged diesel engine were studied in this paper. With or without EHN, the increase in injection pressure and the advance in injection timing lead to an increase in the peak temperature, pressure, and heat release rate, as well as a shortening of the combustion duration. Adding EHN witnesses reduced requirements for methanol ignition, including a decreased peak temperature, pressure, and heat release rate, a significantly shortened ignition delay period, and an extended combustion duration, which thus results in a reduced indicated thermal efficiency. This study innovatively develops a 3D model of a compression combustion engine applicable to in-cylinder direct injection pure methanol fuel and EHN under small load conditions, which provides a reference for future research and development of small-load pure methanol compression combustion engines and has certain guiding significance.

Designing a Twin Frequency Control DC-DC Buck Converter Using Accurate Load Current Sensing Technique

In this paper, a buck DC-DC converter with the proposed twin frequency control scheme (TFCS) and accurate load current sensing (ALCS) was designed and implemented with 0.18 µm CMOS technology for a supply voltage ranging from 2.0 to 3.0 V, which is compatible with state-of-the-art batteries (NiCd/NiMH: 1.1–2 V, Li-Ion: 2.5–4.2 V). The proposed converter yields a peak efficiency of about 92.7% with a load current of 30 mA. Furthermore, it only occupies a silicon area of 1.3 mm2. The proposed buck converter is dedicated for smartphone applications whereby it spends most of its time in idle, low load conditions.

Towards the superlubricity of polymer–steel interfaces with ionic liquids and carbon nanotubes

Frictional losses are responsible for significant energy waste in many practical applications, and superlubricity with a coefficient of friction lower than 0.01 is the goal of tribologists. In this paper, metal-on-polymer contact was analysed and close to superlubricity conditions for this material configuration were explored. A new lubricant has been proposed hinge on the phosphorus-based ionic liquid and carbon nanotubes as thickeners. Additionally, carbon nanotube mesh was doped with copper nanoparticles that allowed for the close to superlubricity state in a mild steel/polymer contact configuration under low normal load conditions. The adsorption of phosphorus onto metallic and polymer surfaces has been reported in EDS analysis. The formulation of the new lubricant allowed for stable dispersion with a carbon nanotube content as low as 0.1% wt. The carbon nanotubes and Cu nanoparticles have been analysed using TEM and SEM imaging. A tribological test in a block-on-ring system has been carried out. The wear of material, topography, and surface free energy have been analysed along with SEM/EDS images to explore the underlying mechanisms of friction and wear.

A simplified space vector modulation for the single-phase active power decoupling quasi-Z-source inverter

The double-line frequency ripple power of the single-phase quasi-Z source inverter (qZSI) will result in a large designed qZS impedance on the dc side, which can be greatly reduced by the coupled-type active power decoupling (APD) method. However, the traditional sinusoidal pulse width modulation (SPWM) for the APD-qZSI needs extravagant APD storage capacitance and may cause abnormal operation under low load conditions. Classical space vector modulation (SVM) has higher flexibility and dc-link voltage utilization, but it cannot be directly applied to the APD-qZSI. In this paper, a simplified SVM method for the coupled-type APD-qZSI is proposed, where the switching time sequence is transformed to carrier-based pulse width modulation, so the shoot-through control of the qZSI is easy to implement. Next, the passive component parameters and normal operation range of the traditional SPWM and the proposed SVM are analyzed and compared. The proposed SVM has a smaller APD storage capacitance but a slightly larger ac side filter inductance. In addition, the decreased current of the APD branch under SVM can help suppress the abnormal operation of the inverter, so the APD-qZSI can operate at a lower load condition. Finally, experimental results validate the effectiveness and superiority of the proposed SVM method.

A CFD ignition model to predict average-cycle combustion in SI engines with extreme EGR levels

Control of the combustion process in Spark-Ignition (SI) engines operated with extreme dilution from exhaust gas re-circulation (EGR) represents one of the major limitations in the industrial design of such technology. Numerical approaches able to describe in detail the formation of the early flame kernel become essential to face such an ambitious task. This work presents a RANS-based multi-dimensional model of the combustion process, including an advanced description of the ignition stage to consider its stochastic re-ignitions within the average cycle prediction. The spark-channel is described as a column of Lagrangian parcels that represent early flame kernels, whose growth is controlled by the laminar flame speed and energy input from the electrical circuit. The spatial evolution of each parcel is computed according to a scaled value of the average-flow speed, to mimic the smooth but short elongation of the mean-cycle channel produced by stochastic restrikes affecting the single-cycle arcs. To clarify this phenomenon and assess the proposed CFD method, a series of experiments are performed in a single cylinder SI engine with optical access, running at a low-load cruise-speed operating condition. Increasing EGR levels are tested up to the onset of misfire, with measurements of the secondary-circuit features and of the flame evolution through high-speed imaging. Satisfactory results are achieved in terms of numerical-experimental comparison of the cycle-averaged in-cylinder pressure, discharge parameters, and spatial flame distribution, demonstrating the reliability of the proposed numerical approach.

Distinct age-related brain activity patterns in the prefrontal cortex when increasing cognitive load: A functional near-infrared spectroscopy study

Researchers have long observed distinct brain activity patterns in older adults compared with younger adults that correlate with cognitive performance. Mainly, older adults tend to show over-recruitment of bilateral brain regions during lower task loads and improved performance interpreted as compensation, but not observed at higher loads. However, there are discrepancies about whether increases in activity are compensatory and whether older adults can show compensation at higher loads. Our aim was to examine age-related differences in prefrontal cortex (PFC) activity and cognitive performance using functional near-infrared spectroscopy (fNIRS) during single and dual N-back tasks. Twenty-seven young adults (18–27 years) and 31 older adults (64–84 yrs) took part in the study. We used a robust fNIRS data methodology consisting of channel and region of interest analyses. Results showed differences in performance between task load conditions and age-related differences in reaction times but no age-group effects for accuracy. Older adults exhibited more bilateral PFC activation compared with young adults across all tasks and showed increases in brain activity in high compared to low load conditions. Our findings further support previous reports showing that older adults use compensatory recruitment of additional brain regions in PFC to maintain cognitive performance but go against the notion that such compensation is not present at higher cognitive loads. Additionally, our results indicate that fNIRS is a sensitive tool that can characterize adaptive cortical changes in healthy aging.

Modeling for on-line monitoring of carbon burnout coefficient in boiler under partial load

Combustion stability of boiler deteriorates under low load, making carbon burnout coefficient decrease, further reducing boiler thermal efficiency. The online monitoring methods of carbon burnout coefficient and boiler thermal efficiency can track energy efficiency levels of boiler in real-time under low loads. It is of great practical significance to optimize and adjust combustion conditions of boilers and upgrade boiler real-time energy efficiency. Nevertheless, extremely difficult challenge for online monitoring technology of carbon burnout coefficient seriously restricts the online monitoring of boiler thermal efficiency.In this background, an innovative theoretical model between excess air coefficient and carbon burnout coefficient is derived according to incomplete combustion equation inside furnace. Calculation method of excess air coefficient is proposed with a brand new perspective on energy balance of economizer. Subsequently, on-line monitoring model of carbon burnout coefficient and boiler thermal efficiency is constructed and verified.The online monitoring results of a 600 MW unit indicate, lower carbon burnout coefficient magnifies the degree of virtual height of calculation results and calculation error from traditional methods of national standard for calculating excess air coefficient. This operating mode results in a significant shortage of actual air flow into boiler under partial load.Carbon burnout coefficient, showing an upward trend with unit load increasing, is as high as 0.99 with unit load of 489 MW. As unit load decreases to 161 MW, carbon burnout coefficient decreases to 0.80. Additionally, combustion conditions fluctuation is greatly influenced by changing in coal quality. Under partial load, volatility in carbon burnout coefficient increases with electrical load below 300 MW. Combustion stability and combustion efficiency of boiler under low load significantly decrease. The variation in exhaust flue gas heat loss of boiler with unit load changes is relatively small due to opposite effect by exhaust gas temperature and excess air coefficient. Actually, changing trends and fluctuation degree of boiler thermal efficiency are mainly influenced by carbon burnout coefficient with a variation in load. Overall, boiler thermal efficiency, affected by heat loss of incomplete solid on combustion, fluctuates greatly at low loads. The implementation of online monitoring for carbon burnout coefficient provides a quantitative basis for improving boiler energy efficiency under low load conditions.

Biodiesel from Waste Cooking Oil: Highly Efficient Homogeneous Iron(III) Molecular Catalysts

This article presents an efficient iron(III) molecular catalyst for the production of biodiesel from waste vegetable oils. The approach involved an initial screening of eight salophen complexes with various substituents on the arene rings, leading to the selection of the simplest unsubstituted species as the most active catalyst. Under optimized conditions, this catalyst demonstrated the capability to achieve complete conversion of the oil at a low catalyst loading (0.10% mol/mol) and convenient conditions (160 °C, 20/1 MeOH/oil ratio).