Comfort Index Research Articles

The influence of unconventional assembly techniques on the comfort indicators of waterproof materials

The present paper aims to highlight the correlations between the comfort indicators of waterproof cotton-based fabrics, and the specific parameters of unconventional assembly technology. The materials considered include layers of Gore-Tex film, serving as substitutes for waterproof materials, intended to manufacture outerwear products such as protective equipment (jackets and overalls), which are breathable waterproof membranes. The comfort indicator values were obtained through standardised methods, and data processing and representation in two-dimensional (2D) and three-dimensional (3D) systems using correlation/graphing methods were carried out in Excel software, and using Jandel Table Curve 3D v2. Although experimental research can be extended to include specific functions related to durability indicators, this study focused theoretically and experimentally on how the variation in temperature of the low-pressure hot air jet can lead to changes in the vaporization coefficient, air permeability index, and thermal conductivity coefficient. The relationship between the comfort indicator values (thermal conductivity coefficient, air permeability index, and vapour permeability coefficient) of the considered materials and the treatment parameters of the installation (pressure, temperature, velocity) is expressed through statistically adequate mathematical models, highlighted by a correlation coefficient R = 0.983, with significance certified by the Fischer test. The study of comfort indicators was conducted under optimized treatment parameters, ensuring durability and presentation value functions in the treatment zone remain unchanged compared to those of the base materials.

Study on the ride comfort of a high-speed sleeper train

The difference in vibration characteristics between passengers and sleepers on high-speed sleeper train ride comfort was rarely studied. This work proposed a 3D rigid-flexible passenger-sleeper-vehicle-track coupling model. The multi-rigid body dynamic method models the supine passengers and sleepers. The detailed car body FE (finite element) model, which contains the train's suspension equipment, is established. Based on the coupling model, the ride comfort index, calculated based on different standards, is analyzed. The difference in the ride comfort index, evaluated using the acceleration at the sleeper and passenger, is compared. Also, the impact of the car body flexibility and the passenger-sleeper model parameters on the ride comfort of a supine human is studied. Then, the ride comfort of the high-speed sleeper train is analyzed when the train is subject to track irregularities excitation, and aerodynamic force (meeting). The results show that using the acceleration of the sleeper can overestimate the ride comfort of the high-speed sleeper train. The head-, and pelvis-sleeper contact parameters are crucial for high-speed sleeper train ride comfort. The ride comfort of the high-speed sleeper trains decreases sharply when trains meeting and passing the special track section.

Architectural design strategies based on climatic zoning and thermal comfort indices (Case study: Qazvin)

Architectural design strategies based on climatic zoning and thermal comfort indices (Case study: Qazvin)

Changes in the Climate Comfort of the Coast of Spain (1940-2022)

The Spanish coastal regions register specific climatic conditions due to the combination of mild temperatures with little variation throughout the year, high relative humidity and the influence of maritime storms. In summer, the climatic comfort conditions are excessively hot, especially on the Mediterranean coast of Spain. Understanding these conditions and analysing the temporal evolution of recent decades, as well as regional differences, is fundamental for future summer tourism planning in the coming decades. This study analyses the principal 37 coastal tourist hubs of Spain grouped into 10 large regions (the Atlantic, Cantabrian, Mediterranean coasts, and the two archipelagos of the Balearic and Canary Islands). Daily data drawn from the ERA-5 (Copernicus) atmospheric reanalysis from 1940 to 2022 have been used (mean air temperature, mean relative humidity, and mean wind speed), with which the Climate Comfort Index has been calculated (CCI) by González (1998). The results show a significant reduction of the CCI in all the coastal areas analyzed, being more relevant in winter (-0.10 decade). The decrease in the index implies a decrease in cold thresholds and an expansion of comfort throughout the study area, especially in the central Mediterranean and Cantabrian Sea. For its part, in summer, the most important decreases (-0.07 and -0.08 / decade) show an increase in the most important climatic discomfort on the Cantabrian Coast – Euskal Kostaldea and on the Costa Brava-El Garraf, with a significant intensification and expansion temporary thermal sensation of heat. In other coastal sectors, in recent years, the climatic thresholds of heat and extreme heat have been reached for the first time.

Multi-objective optimization design of automobile seat backrest considering coupling effect

To investigate the impact of the coupling effects of carbon fiber reinforced polymer in the seat back layer on the performance of car seats, this paper presents a comprehensive optimization design method for composite materials. In detail, the finite element models firstly established and validated through five typical working conditions of automotive seats based on experimental data. Then, the optimized variables are divided and determined through backrest stress nephograms for each working conditions of the automotive seats, in which the various perspective are taken into account, such as the total mass of seat backrest, safety performance, and comfort index. Subsequently, an optimization strategy for unequal thickness layers lay-up design is constructed, which combines strength factors, optimal Latin hypercube sampling, best-worst method, gray relational analysis, and Visekriterijumsko KOmpromisno Rangiranje method for the optimal design of the automotive CFRP seat backrest. Additionally, the impact of layer coupling effects on different performance indices of the seat is examined through simulating and analyzing the seat backrest with various layer coupling types, while incorporating the classical laminate theory. The study reveals that by minimizing the laminate coupling effect, the comfort of the seat can be enhanced. Finally, a comprehensive comparative analysis of the optimal trade-off solution is carried out in terms of optimization strategies. The results show that ensuring the safety performance, the total mass of the seat backrest decreased by 21.3%, as a result of the optimization strategy proposed in this paper, and the comfort performance is also improved to some extent. Therefore, the multi-objective optimization strategy proposed in this paper performs well in terms of effectiveness and provides a reliable reference for related composite material multi-objective optimization.

The Impact of Urban Roughness on Outdoor Thermal Comfort in Hot Arid Climate

The proportion of the world's population living in cities is rapidly increasing, presenting new challenges to the urban environment and quality of life. Among these challenges is the urban environment's impact on residents' outdoor thermal comfort, which can affect their health and well-being. Urban roughness, which includes building and street heights, has a significant impact on the thermal environment of urban areas. Changes in these factors cause variations in temperature distribution, wind speed, and humidity, which affect how people perceive thermal conditions. The research problem is the effect of urban roughness on outdoor thermal comfort in hot arid climate, specifically the height of buildings and the density, for a case study in (Al-Bab Al-Sharqi) in Baghdad city. Measurement method that employed the computer programs (Rino8 and Grasshopper) to calculate the thermal comfort index (UTCI) and its impact on various climatic variables. The findings revealed that the thermal comfort index and the climatic factors associated with it vary depending on the configuration of buildings.

Research on the mechanism and measures of riding comfort deterioration in a low floor tram

With the global widespread preference for low-floor trams, the expectation for tram riding comfort has been increasingly heightened. This paper identifies an abnormal riding comfort problem (ARCP, characterized by an excessive and W-shaped distribution of riding comfort) during dynamic field tests on a low-floor tram. To address ARCP, a multi-body dynamics model of the tram was constructed and validated its accuracy through dynamic field tests. By integrating track irregularities and wheel-rail contact analysis, the riding comfort index was assessed and reproduced the ARCP phenomenon. Linearization and time-domain integration studies were conducted on the mechanisms and measures to resolve the ARCP. The research findings reveal that the primary cause of the deterioration in the mean comfort index is the large amplitude of the track irregularity and the low equivalent conicity of the wheel-rail contact relationship. The main reason for the W-shaped distribution of riding comfort is the weaker inter-vehicle constraints and the lack of lateral energy-absorbing devices. Finally, optimization measures were proposed, including reducing the lateral stiffness of the second suspension, altering the carbody structural parameters, and modifying the inter-vehicle connection devices. This research enriches the study of tram dynamic performance and offers insights that may contribute to the resolution of ARCP.

Effects of Climate Change on the Future Attractiveness of Tourist Destinations in Greece

Climate change is a major challenge for the global tourism sector, affecting destinations worldwide. Greece, known for its scenery and abundant cultural history, is particularly vulnerable to these impacts. Tourism is a key driver of Greece’s economy, yet climate change threatens both natural environments and cultural sites. To evaluate the impacts of climate change on different types of Greek tourism (beach, sightseeing, winter tourism in mountainous areas), the widely used Holiday Climate Index (beach and urban versions) alongside three additional climatic indices customized for Greek climatic conditions, namely the Urban Climate Comfort Index, the Beach Utility Index, and the Mountainous Winter Climate Index were utilized for top tourist destinations of Greece. The results indicate that urban tourism may face challenges during peak summer months due to rising temperatures, but the shoulder seasons (April–May and September–October) will offer improved conditions, potentially extending the tourist season. For beach tourism, favorable conditions are expected to increase from April to October, with significant gains in June and September. Winter tourism in mountainous areas, especially snow-dependent activities like skiing, is at risk due to the declining snow availability. Overall, the study highlights both the challenges and opportunities posed by climate change for Greece’s tourism sector. It emphasizes the importance of adaptation strategies, including infrastructural improvements and promoting alternative activities, to minimize negative impacts and enhance the future attractiveness of Greek tourism.

Evaluating and enhancing the applicability of thermal comfort indices in diverse outdoor environments using Bayesian and random forest regression

This research aims to evaluate and improve the applicability of three commonly utilized thermal comfort indices—standard effective temperature (SET), physiological equivalent temperature (PET), and universal thermal climate index (UTCI)—in outdoor environments. The study was conducted in four typical spaces of a university in Xi’an, China, covering different environmental settings: East Lake (Place 1), tree-lined path (Place 2), campus playground (Place 3), and campus square (Place 4). A total of 322 volunteers participated by completing a subjective sensory questionnaire in randomized environments, and on-place meteorological data were collected. The study yielded three primary findings. First, the tree-lined path (Place 2) was identified as the most comfortable outdoor space on the university campus during summer, whereas East Lake (Place 1) was the least comfortable. Second, substantial residuals were observed for SET, PET, and UTCI across different places when assessing the thermal comfort variations experienced by the subjects. Third, Bayesian regression and random forest regression were employed to analyze and adjust the thermal comfort indices. The comparative study found that after correction, the model explanatory power of PET increased by up to 20%, with the standard deviation of residuals decreasing by up to 0.314 and MSE decreasing by up to 0.1912. The model explanatory power of SET increased by up to 31.2%, with the standard deviation of residuals decreasing by up to 0.3867 and MSE decreasing by up to 0.3012. For UTCI, the model explanatory power increased by up to 10.5%, the standard deviation of residuals decreased by up to 0.2215, and the MSE decreased by up to 0.1002.

A cooperative lane change control strategy for cooperative adaptive cruise control platoons with insufficient headway gaps

Cooperative Adaptive Cruise Control (CACC) platoons contribute to enhancing road traffic safety and efficiency. However, creating suitable headway gaps for CACC platoons to change lanes is a challenge. This paper proposes a cooperative lane change control strategy for CACC platoons in mixed traffic environments where suitable headway gaps on the target lane are insufficient. Firstly, a cooperative longitudinal and lateral control strategy for CACC platoons is designed. Once longitudinal control ensures that the headway gap on the target lane meets the criteria, the vehicles are controlled to complete the lane change and resume cruising in their original formation. To achieve the longitudinal control objectives of gap generation by cooperative deceleration before lane change and cruising after lane change, a longitudinal cooperative control strategy that can independently create the lane change gap is proposed based on an adaptive weight model predictive control. Finally, the lane change headway gaps in the proposed strategy are generated sequentially for each vehicle, a contrast experiment is designed where the lane change headway gap is generated once and vehicles change lanes simultaneously. The effectiveness of the proposed strategy is validated through numerical simulation combining CarSim and Matlab/Simulink. The results show that the CACC platoon completed the lane change successfully under the control of the proposed strategy. Compared to the contrast simulation, in both low-speed and high-speed highway scenarios, the average speed standard deviation under the proposed strategy is reduced by 48.3 % and 39.9 % respectively, while the average comfort index decreases by 11.7 % and 5.9 %.

Park thermal comfort and cooling mechanisms in present and future climate scenarios

Extreme heat is Australia’s most perilous natural hazard, and increasing urban temperatures due to climate change are a growing concern. Consequently, there is growing interest in developing nature-based solutions (i.e., greenery and vegetated surfaces) to cool urban areas. Appropriately designed urban parks are anticipated to be crucial for maintaining thermal comfort as temperatures rise. The two main diurnal cooling mechanisms of urban parks are shade provision and vegetation transpiration. However, limited studies have examined the cooling performance of vegetation through transpiration, especially in the southern hemisphere. This study addresses this gap by examining the microclimatic conditions, cooling benefits, and thermal performance of a typical neighbourhood park in Perth, Western Australia, with a focus on the cooling performance of vegetation through shade and transpiration. Present and future microclimates were modelled and simulated for average and hottest summer days based on 25 years of local weather data and projections for 2090 under the Representative Concentration Pathway (RCP) 8.5 scenario. The findings reveal that trees provided diurnal cooling benefits for park users by lowering the Universal Thermal Comfort Index (UTCI) by up to 17°C, with this benefit persisting in projected 2090 conditions. This cooling benefit was predominantly achieved through shade provision, with marginal contributions from transpiration. Additionally, on hot days, as leaf temperature exceeded 30°C, increased stomatal resistance led to reduced transpiration. Therefore, more attention must be paid to transpiration cooling limits due to stomatal closure during hot hours to improve cooling performance in park design. Moreover, comparing different plant species’ behaviour and adaptability on hot days is crucial, especially in future climatic conditions.

Ocular neuropathic pain in a real-world patient cohort with dry eye disease: A save sight dry eye registry study

PurposeTo compare patient demographics, clinical signs, and questionnaire scores in dry eye disease (DED) patients with and without ocular neuropathic pain. MethodsA cross-sectional cohort study was performed using the Save Sight Dry Eye Registry (SSDER). Patients were divided into two groups based on a clinician diagnosis of ocular neuropathic pain and Tear Film and Ocular Surface Society Dry Eye Workshop II definitions. Patient demographics, Ocular Surface Disease Index (OSDI) and Ocular Comfort Index (OCI) scores, and DED signs were compared along with Patient Health Questionnaire-4 (PHQ-4) scores, average screen time and treatment compliance. Statistical analyses included descriptive statistics, Mann-Whitney U test, Chi-squared test of independence, and Fisher's exact test. P-values were Bonferroni corrected (p*). ResultsData from 298 patients with DED symptoms and signs (26 with ocular neuropathic pain) were analysed. There was no statistical difference in patient demographics (p*>0.0063). Patients with ocular neuropathic pain had worse final, domain, and pain-related question scores for the OSDI (p*<0.0031) and OCI (p*<0.0039) and had higher scores for anxiety and depression for the PHQ-4 (p*<0.0083). Patients with ocular neuropathic pain had a lower rate and severity of meibomian gland dysfunction (p*<0.0063). ConclusionReal-world data from the SSDER demonstrated patient demographics and clinical signs poorly differentiated patients with ocular neuropathic pain within a DED cohort. Patients with ocular neuropathic pain reported significantly worse OSDI and OCI scores, indicating greater symptom severity. While this highlighted symptom differences, further research is required to determine whether OSDI and OCI scores can assist in identifying ocular neuropathic pain in DED.

Significance analysis and evaluation of the impact of a new sustainable ecosystem on the microenvironment of multi-level thermal humidity

Active living walls represent sustainable green technology that improves indoor thermal environment. However, the improvement effect of active living walls in these environments still needs to be further explored, especially with regard to humidity. This study aims to effectively improve the indoor thermal humidity microenvironment of residential buildings, a new sustainable ecosystem (NSES) was developed. NSES integrates plants, spray cooling, and a fan, offering four operation modes, all controlled through intelligent monitoring based on the indoor conditions. Under the working scale of limited space in the microenvironment, evaluating system performance has solved the problem of thermal comfort. In addition, subjective questionnaires are used to evaluate human thermal comfort indicators. The results indicate that (1) Mode 1 exhibits the best performance on the microenvironment throughout the season at a distance of 0.5 m horizontally and 1.1 m vertically from NSES; as the vertical height and horizontal distance increase, performance gradually weakens. (2) Under the conditions of 0.5 m horizontal distance and 1.1 m vertical height, NSES has the best improvement effect on the microenvironment on sunny summer days; an average temperature decrease of 5.6 °C and an average humidity increase of 27.5 % were achieved. (3) NSES can improve human comfort, with thermal comfort zones ranging from 22.4 to 24.3 °C in autumn, and 22.4–23.8 °C in spring. These results highlight the potential value of NSES in improving the microenvironment and enhancing human thermal comfort. This study emphasizes the importance of NSES in appropriately selecting distance, height, season, and climate.

Detailed thermal environment classification of high geothermal tunnel based on thermal comfort indices

High temperature and high humidity in geothermal tunnels pose significant risks to the well-being of construction workers. This study aims to establish critical environmental thresholds to protect workers in these challenging conditions. Field tests were conducted in a high geothermal tunnel in southwest China, continuous measuring parameters such as dry bulb temperature, relative humidity, wet bulb globe temperature (WBGT), skin temperature, and heart rate. The collected data were analyzed, leading to the development of a nonlinear programming mathematical model. This model enabled a systematic classification of the tunnel's environmental conditions and the calculation of threshold values for various environmental parameters. Furthermore, critical thresholds for heat stress indicators such as the discomfort index (DI), heat index (HI), and relative strain index (RSI) were determined. The study categorized the tunnel's hot and humid environment into five distinct zones: comfortable zone, general comfortable zone, safety zone, heat tolerance zone, and danger zone. The findings indicate that in this geothermal tunnel, the comfort zone thresholds are 26 °C for dry bulb temperature, 30 % for relative humidity, and 20 °C for the WBGT index. The safety zone thresholds are 37 °C, 64 %, and 32 °C, while the danger zone thresholds are 43 °C, 81 %, and 40 °C, respectively. For heat stress indices, the safety thresholds for DI, HI, and RSI are 25.42 °C, 26.31 °C, and 0.28, while the danger thresholds are 28.59 °C, 35.30 °C, and 0.38, respectively. This research provides essential insights for safeguarding the health of construction workers operating in high geothermal tunnel environments.

ERGONOMIC AND LOGISTIC ENSURING THE REQUIREMENTS FOR THE COMFORT DURING THE ORGANIZATION OF PASSENGER TRANSPORTATION IN A SMALL-CAPACITY BUS

Purpose. The most important advantage of passenger transport by road is the high quality of transport service, which depends on the organization of the transport process, structural features and technical condition of the rolling stock used and the route, the development of the route network and other factors. Comfort reflects the properties of bus passenger transportation, which lead to the creation of the necessary service conditions and convenience for passengers in the bus, at the start-end and transit points on the basis of regulatory documents approved in the prescribed manner. Features of the design of small-capacity buses in terms of comfort and safety of passenger transportation and provision of proper travel conditions mostly determine the scope of use of buses of this class by types of connections and length of routes. The purpose of the paper is the development of a structural model, based on the analysis of the main factors affecting the determination of the comfort of a small-capacity bus for urban transportation during the transportation of passengers. Methods. The analysis of literary sources showed that indicators of comfort (as well as indicators of information service, speed, timeliness, safety of cargo, safety), which refer to indicators of the quality of passenger transportation, are decisive in this group of indicators. From the point of view of Ukrainian legislation and regulatory framework, the concepts of passenger bus capacity and comfort are analyzed. The main factors that determine the comfort of small-capacity buses for urban transportation during the transportation of passengers are determined. Ensuring the comfort of passenger transportation in a small-capacity city bus is determined by compliance with ergonomic requirements, which, in turn, depends on the design features of the arrangement of the area intended for passengers. Scientific novelty. It is proposed to evaluate the comfort category in the urban public road transport system using a structural model that combines two sets of factors – logistic and ergonomic. The logistic set of factors includes characteristics in time and space, that is, characteristics of comfort outside the means of urban public road transport. The ergonomic set of factors includes characteristics that describe comfort in vehicles. Practical significance. On the basis of this model, possible ways of ensuring ergonomic requirements for the layout of the interior and interior of small-capacity buses for urban passenger transportation are proposed. It was established that the main factors of the redistribution of transport mobility between urban passenger transport and transport for individual use are the insufficient comfort of passenger transport or the insufficient density of the route network.

Health risk assessment of residential overheating under the heat waves in Guangzhou

During extreme heatwave events, indoor overheating caused by power outages poses a significant threat to human health, especially for low-income groups exposed to hot and humid conditions for extended periods. However, currently, the definition and quantification standards for indoor overheating are not well-defined, and relying solely on thermal comfort indicators is insufficient to accurately assess the health risks associated with indoor overheating. This study proposes the use of maximum heat index (HImax) and heat index hazard hours when the heat index exceeds the caution level (HIHHCaution) to assess the health risk of indoor overheating. Taking various types of residential buildings in Guangzhou as examples, the study employs field surveys, simulation analysis, and statistical regression to analyze the impact of power outages during heatwaves on the indoor thermal environment and key human thermal physiological parameters, thereby establishing the basis for measuring indoor overheating and reference thresholds for assessing heat health risks. The results indicate that for young adults and the elderly, HIHHCaution exceeding 1174 °C·h and 850 °C·h respectively, or HImax nearing 55 °C, are likely to result in heat-related illnesses. In Guangzhou, most urban village housing with poor insulation cannot withstand the risk of power outages lasting more than a day during heatwaves, while old housing and commodity housing that meets the energy-efficiency standards of different periods still face varying degrees of indoor overheating risk. The findings enhance understanding of indoor overheating health risks and provide a scientific basis for strategies to improve living environments during heatwaves.

Microclimate analysis of Ganga riverfront in Patna: spatial form perspective

ABSTRACT The investigation in this research scrutinizes the influence of spatial form factors on thermal comfort along the Ganga riverfront trail during the spring season. Understanding how spatial form factors impact local climate parameters and PET values is crucial for optimizing thermal comfort in urban waterfronts. The research addresses the need to improve thermal comfort in rapidly urbanizing areas through strategic urban design. Data were collected from eight measurement points along the riverfront, analyzing Air Temperature (Ta), Relative Humidity (RH), Wind Velocity (v), Surface Temperature (Ts), Global Radiation (G) and Mean Radiant Temperature (Tmrt). The study employs a combination of field measurements and statistical analysis to assess the correlation between spatial form factors and thermal comfort indicators. Findings reveal that lower building height (Hb) values are associated with more favorable thermal comfort conditions, while higher Hb negatively impacts thermal comfort. The study also highlights that building spacing (ADb) influences thermal comfort, with findings contrasting those from composite climates, suggesting a need for context-specific design strategies. The research underscores the significant role of Ta and v in shaping Physiological Equivalent Temperature (PET), aligning with previous studies in diverse urban contexts. The results emphasize the critical impact of spatial form on microclimate and thermal comfort, informing urban design and planning to enhance livability along the Ganga riverfront. This study contributes to the field by providing empirical evidence and practical insights for developing thermally comfortable walking trails.

Evaluating thermal comfort indices for outdoor spaces on a university campus

This study evaluates the applicability of three thermal comfort indices—Physiologically Equivalent Temperature (PET), Standard Effective Temperature (SET), and Universal Thermal Climate Index (UTCI)—in various outdoor environments on the campus of Xi’an University, China. Meteorological data were collected on sunny days using a portable weather station at a height of 1.5 m, and subjective questionnaires were administered to 25 healthy university students over three months to gather Thermal Sensation Votes (TSV) and Thermal Comfort Votes (TCV). The study was conducted at four distinct outdoor locations: a lakeside area (Location 1), a shaded path (Location 2), a sports field (Location 3), and a plaza (Location 4). PET, SET, and UTCI values were calculated from the collected data using Rayman software. The analysis revealed significant differences in thermal comfort across the four locations, with the highest proportion of subjects feeling hot at the sports field (54.4%) and the highest proportion feeling cold at the lakeside (39%). The shaded path had the highest proportion of subjects feeling comfortable (79.4%), while the lakeside had the lowest (60.1%). The results indicated that SET underestimated thermal sensation at Locations 1, 3, and 4, necessitating calibration. PET was suitable for Locations 2, 3, and 4 but failed to reflect the thermal sensation at Location 1 due to prolonged sun exposure. In contrast, UTCI demonstrated applicability across all locations. To enhance accuracy, revised indices SET’ and PET’ were formulated using the mean-median method, providing more precise thermal comfort assessments. These findings underscore the limitations of SET and PET under specific conditions and highlight the robustness of UTCI, offering valuable insights for urban planning and design aimed at improving outdoor thermal comfort and well-being.

Effects of oral carbohydrate loading in patients scheduled for painless bidirectional endoscopy: a prospective randomized controlled trial

PurposeTraditional fasting causes considerable discomfort without added assurance of security, whereas oral carbohydrate beverage offers an alternative to improve medical experience. This study aims to explore the impact of different types and dosages of oral fluids loading before painless bidirectional endoscopy on the gastric emptying and wellbeing.Methods180 patients arranged for bidirectional endoscopy with intravenous anesthesia were randomized: patients in the control group (Group C) obeyed standard fasting; the 200 mL carbohydrate group (Group P1), 400 mL carbohydrate group (Group P2), 200 mL water group (Group W1) and 400 mL water group (Group W2) respectively consumed 200 mL or 400 mL corresponding clear liquids 2 h before the procedure. Gastric emptying metrics under ultrasound, subjective comfort indexes, periprocedural blood glucose and vital signs were contrasted among the groups.ResultsNo significant differences were detected in the gastric emptying including CSA (cross-sectional area), GV (gastric volume), cGV (corrected gastric volume) and the three-point grading system among groups, and none had a cGV > 1.5 mL/kg before anesthesia. Participants in Group P2 experienced less preprocedural thirst and mouth dryness, so as the postprocedural thirst, mouth dryness and hunger. Periprocedural blood glucose and MAP had the similar trend in all groups. The occurrence of hypotension, bradycardia, hypoxia, and the required norepinephrine was comparable among the groups.ConclusionsOral beverage loading with 200 mL or 400 mL can be safely applicated 2 h before painless bidirectional endoscopy without increasing the gastric volume. 400 mL carbohydrate solution effectively relieves the discomfort and could serve as a consideration.Trial registrationRegistered in the Chinese Clinical Trial Registry on December 5, 2023 (ChiCTR2300078319).

Performance evaluation of a novel semi-active absorption and isolation co-control strategy with magnetorheological seat suspension for commercial vehicle

Abstract Vibration isolation performance of seat suspension plays a critical role in protection of drive’s physical health as the last barrier. In this paper, the integrated magnetorheological (MR) dynamic tuned mass damper (TMD) is firstly designed and utilized into seat suspension. A semi-active co-control algorithm with MR damper and MR TMD is designed, analyzed and validated by comparative experiments. The dynamic models of two MR devices have been tested and fitted. Comparing with simulation and experimental results under various excitations and control conditions, this co-control algorithm with MR TMD is validated to be highly effective. The transmissibility at resonance frequency reaches to 0.81 which is less than 1. This phenomenon has hardly been investigated in seat suspension. It illustrates that resonance has been suppressed and improved significantly. The peak acceleration decreases to 1.19 m s−2 with a reduction of 57.2%, in contrast to passive condition with MR damper. The comfort index is increased by 45.6% under random excitation than passive condition. According to these comparisons, the vibration isolation property and comfort of seat suspension can be further improved by the proposed co-control algorithm with two MR devices.