Comfort Performance Research Articles

Hydrophobic/oleophobic nanofibrous filter media with bead-on-string structure for efficient personal protection of dust in mines

Pneumoconiosis in mines occupied more than 90% of the total number of occupational diseases, poses tremendous pressure and challenges on the development of personal protection materials with high dust filtration efficiency and long-lasting comfortable wearing. In this study, a kind of polyethylene terephthalate (PET) based filter media with the bead-on-string structure and hydrophobic/oleophobic property was designed and fabricated by electrospinning technology. Nanoscale silicon dioxide (SiO2NPs) and fluorinated polyurethane (PU) used in this work were benefited for the microstructure, surface energy and hydrophobic/oleophobic property, respectively. The morphology and composition of the membranes were conducted by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and fourier transform infrared spectroscopy (FTIR). Furthermore, the filtration performance, pressure drop, moisture permeability and breathing comfortable performance were measured for the study of personal protection of dust. The results showed that at the air flow of 85 L min−1, PET/SiO2/FPU double-layer nanofibrous membrane showed high filtration efficiency and low pressure drop with the filtration efficiency of 99.96%, pressure drop of 142.5 Pa and quality factor of 0.055 Pa-1, respectively. A long term of 24 h water vapor test had proved that this membrane held an outstanding moisture permeability ability of 5296.325 g (m2 24 h)−1. Compared with the commercial 3701CN filter media, the advantages of the regular breathing frequency and strong heart rate control ability indicated that this PET/SiO2/FPU double-layer membrane had the better wearing comfortable performance with broad application prospects in the personal protection of dust in mines.

Economic model predictive control with terminal set dynamic programming for tracking control

AbstractThis paper focuses on vehicle tracking control issues with consideration of energy efficiency, ride comfort and tracking performance. To address this issue, an economic model predictive control (EMPC) framework is proposed by taking average performance into account and introducing a time‐varying terminal set. We integrate an economic model predictive controller and a terminal controller with a feedback gain related to the time‐varying terminal set into the proposed EMPC framework. An acceleration‐dependent average constraint is designed and incorporated into the MPC optimization problem to facilitate the convergence of the actual acceleration to the desired one, which enables the vehicle to implement a smooth driving style that boosts energy economy. A tuning factor in the average constraint has the capacity to balance energy consumption and control performance. Under the premise of invariance constraints, a dynamic terminal set is constructed by solving a dynamic programming problem online, which enables an arbitrary location and scale of the terminal set at each iteration by taking the current and predicted tracking errors into account. This allows a reduction in the conservativeness of an economic model predictive controller in the sense of both the region of attraction and the cost bound. Recursive feasibility of the MPC optimization problem and the terminal set dynamic programming is ensured, and average performance is not worse than the performance with an optimal steady‐state operation. Moreover, the convergence of the closed‐loop tracking error to the optimal steady‐state is guaranteed by using the dissipativity theory. The effectiveness of the proposed algorithm is verified by numerical comparisons with different controller parameters and standard EMPC.

Clinical and microbiological comparison of knotless/barbed and silk sutures for impacted third-molar surgery.

Several types of suture materials are available for oral surgery. However, the most used non-resorbable suture in oral surgery is 3/0 silk. The aim of the present study was to compare the effectiveness of knotless/barbed sutures with silk sutures during the postoperative period after the third molar surgery in terms of clinical and microbiological parameters. The study comprised 38 patients who underwent surgical extraction of a mandibular impacted third molar. The patients were divided into two groups. The mucoperiosteal flap was closed using 3/0 knotless/barbed sutures for the test group and 3/0 silk sutures for the control group. The duration of suturing was recorded during surgery. Pain level, postoperative edema, and trismus were measured at 3 and 7 days after surgery. The status of plaque formation on the sutures was scored using the Plaque Index at 3 and 7 days after the surgery. At 7 days, the suture materials were removed and submitted to the laboratory for microbiological analysis. The level of pain during suture removal was also recorded by a Visual Analog Scale. The duration of suturing in the barbed sutures group was found significantly lower than in silk sutures (P<0.05). There was no significant difference between the suture types in terms of trismus and edema at 3 and 7 days after surgery (P>0.05). On the third day after surgery and during suture, removal pain scores were statistically significantly lower in the barbed suture group than in the silk suture group (P<0.05). The Plaque Index values of the barbed sutures were statistically significantly lower than that of the silk sutures at 3 and 7 days after surgery (P<0.05). Aerobic, anaerobic, and aerobic/anaerobic mean colony forming units (CFUs) were statistically significantly lower in the barbed suture group than in the silk suture group (P<0.05). Barbed sutures increase the ease of operation and patient comfort with less postoperative pain than silk sutures. Additionally, less plaque accumulation and lower bacterial colonization were found on the barbed/knotless sutures than on the silk sutures.

Parameter Identification of Wheel Polygonization Based on Effective Signal Extraction and Inertial Principle

Violent interactions between wheel and rail caused by the polygonal wheels can strongly influence the operational comfort and safety of railway vehicles. It is an effective tool to dynamically detect wheel defects with the axle box acceleration signals. However, since the onboard vibration signals of the axle box are mixed with abundant noise from track irregularity and vehicle components, it is difficult to ensure the detection accuracy of the polygonal wheel. A novel strategy is proposed to extract the effective signal components and quantitatively identify the polygonal wheel parameters. First, the genetic mutation particle swarm optimization (GMPSO) algorithm is developed to search for optimization parameters of variational mode decomposition (VMD). Specifically, the minimum approximate entropy is adopted for the objective function, and the over-decomposition issue of VMD is addressed by the criterion of center frequencies ratio. Then, the independent components (ICs) are separated from VMD modes and the original signal by fast independent component analysis (FastICA). The dominated signal components related to the polygonal wheels can be decided by the proposed criterion. Finally, the order and amplitude of the wheel polygonal wear are obtained from the effective IC based on the inertial principle. The effectiveness of the proposed parameter identification algorithm is verified by the dynamics simulation and field test, and the estimation accuracy of wear amplitudes outperforms the comparison methods.

Experimental study on the supply air characteristics and thermal comfort of a novel personalized ventilation air terminal device

Personalized ventilation (PV) has a significant potential for improving thermal comfort, inhaled air quality and energy efficiency. A novel PV air terminal device (ATD) based on the function of bath showers was evaluated to determine discomfort related to thermal sensation, draughts, dry eyes and skin irritation. The supply air characteristics and thermal comfort were analyzed using objective and subjective experiments in an environmental chamber. Thirty college students participated in the subjective experiments. Results showed that the proposed PV ATD could provide uniform distributions of air velocity at the human head and chest. Compared with the conventional round-monitor panel ATD, the proposed PV ATD can provide an improved cooling effect, wherein overall thermal sensation was reduced by 0.56 scale, showing a potential for energy saving. Moreover, the proposed PV ATD could produce a highly uniform distribution of local thermal sensation (LTS). Compared with the conventional PV, the proposed PV ATD could reduce the standard deviation of distribution of LTS by 41.7% and reduce overall thermal discomfort by 45.5%. Fewer sick building syndrome symptoms at a lower supply airflow rate of 6.3 L/s was achieved. Consequently, the proposed PV ATD could improve the comfort performance with the usage of lower supply airflow rates.

Hydronic flow path analysis on the thermal comfort performance of radiant cooling system

Construction and operation in the building sector account for more than 1/5th of global energy consumption. Moving on to an energy-efficient cooling technology and eco-friendly building material can lead to energy savings and a reduction in associated CO2 emissions. In the present study, an energy-efficient thermally activated building system (TABS) is integrated with eco-friendly building material, namely, glass fibre reinforced gypsum (GFRG). The proposed hybrid system is termed as thermally activated glass fibre reinforced gypsum (TAGFRG) system. This system is not only energy-efficient and eco-friendly but also provides better thermal comfort. An experimental room is constructed with the TAGFRG roof within the Indian Institute of Technology Madras campus, Chennai, i.e., in a tropical warm and humid climate zone. The TAGFRG roof has reinforcement in every third cavity with cooling pipes, while in the other two cavities, cooling pipes are embedded with air gap and partial reinforcement. The TAGFRG roof has four parallel loops of cooling pipelines, and each loop consists of one reinforcement zone (RZ) and two air gap zones (AZ1 and AZ2) in series. According to the water flow path in a single loop, various combinations of the flow path, i.e., RZ → AZ1 → AZ2, AZ1 → RZ → AZ2 and AZ1 → AZ2 → RZ, have been analyzed. According to the adaptive thermal comfort model, the water flow path has a negligible effect on thermal comfort. The average operative temperature for all the cases investigated varies between 28.1 and 29.2 °C. The operative temperature is always within the 90% band of thermal comfort, as per the adaptive comfort model.

Examination of energy and visual comfort performance of thermo-chromic coatings for cellular offices

Examination of energy and visual comfort performance of thermo-chromic coatings for cellular offices

ENHANCING THE PROTECTION PROPERTY ON SILK FABRIC BY THE TREATMENT OF POLYACRYLIC ACID AND CHITOSAN

Silk is valued as one of the prominent protein textile fibers under the animal category famous for the distinct properties such as lustrous appearance, comfort performance, remarkable shiny sheen and also towards the bio-applications. In general, silk is highly sensitive and delicate; hence, there is a need for the protection in order to protect silk from the unwanted impacts of chemicals, light and insects. According to this consideration, in this work it is decided to give an application with polyacrylic acid (PA) and chitosan (CT) followed by adopting coloration process using selected natural dyes and a synthetic reactive dye. The silk fabric samples were undergone to specific tests like measuring the common physical properties, color values and the respective fastness aspects, hand values, antibacterial, uv protection performances and FTIR studies. The outcome of the results give very considerable improvement towards the protection aspects for the silk fabric specific for the textiles / garments and other utility products.

Research on a Comfort Evaluation Model for High-Speed Trains Based on Variable Weight Theory

As a result of the continuous improvement in passengers’ requirements for the quality of train operation, the comfort of high-speed train operation has been paid increasing attention. The evaluation of comfort has gradually changed from the narrow sense of a comfort evaluation model containing only vibration to the generalized evaluation of passengers’ overall satisfaction with the ride environment of specific lines. The factors affecting comfort evaluation include physical, physiological, and psychological aspects. To address the problems that the existing comfort evaluation model has a single index and that the weight determination of some indicators is greatly affected by subjectivity, we built a high-speed train comfort evaluation model based on variable weight theory. Combined with the actual working conditions of the Baolan passenger dedicated line, dynamic detection data and noise monitoring data captured by a track inspection car were combined with a passenger ride comfort questionnaire survey. In addition, the initial weight value of each factor was optimized by constructing an equilibrium function to realize the balance between the various factors, so as to realize the comprehensive fuzzy evaluation of high-speed train comfort. The results show that the comprehensive evaluation result of the comfort degree of the high-speed train on the Tongwei to Lanzhou section of the Baolan passenger dedicated line has a grade of II. The fuzzy scores of the evaluations using variable weights and constant weights were analyzed from the perspective of membership degree. The variable weight optimization avoids the one-sidedness and extremeness of the constant weight calculation. The comprehensive evaluation results are closer to the real situation. The research results can provide a reference for the comfort evaluation of high-speed trains with extreme differences in state values and constant weights and help in the acquisition of more realistic evaluation results.

The Comparison of P, PI and PID Strategy Performance as Temperature Controller in Active Iris Damper for Centralized Air Conditioning System

The topic of maintaining thermal comfort efficiency in the heating, ventilation and air conditioning (HVAC) sector has always been tricky due to numerous challenges. The study focused on the challenge of under-actuated zones in non – residential and commercial buildings. The active iris damper with the integration of thermal controller is proposed to control the indoor temperature. Besides, integration of PID control strategy will be a tempting control system in enhancing the thermal performance of the building. Again, the PID controller has proven good compatibility as a primary closed-loop mechanism to maintain a comfortable room temperature. The development of the control system is done through the Arduino platform with LabVIEW as the front panel and data logging platform. The Heuristic tuning method was employed to obtain optimal gains for P, PI and PID controllers. The performance of each controller was tested by observing their ability to maintain steadily at the desired temperature set point. These tests conveyed that the best controller for this application is the PID controller. It reached the desired temperature set point and maintained it even with a temperature disruption. This study indicates that an active iris damper can effectively maintain the thermal comfort performance of indoor environment with the implementation of PID strategy, thus remedying some of the problems faced by centralized air-conditioning systems.

Coupling analysis and vibration control of vehicle vertical vibration and pitching vibration

The decoupling analysis of vertical vibration and pitching vibration is the basis of improving vehicle comfort performance and realizing vehicle body vibration control. In order to study the coupling behavior of vehicle body vibration, the vibration characteristics of the suspension and the body are analyzed through mathematical modeling and vibration tests. The research shows that the vibration characteristics of the front and rear suspensions are the key factors affecting the coupling between the vertical vibration and the pitching vibration. By controlling the difference ξ between the square of the rotating radius of the body and the product of the distance from the center of mass to the front and rear axles, the correlation between front and rear suspension vibration and the coupling of the body vibration can be reduced effectively. Through the reasonable matching of front and rear suspension stiffness, the ξ value can be reduced effectively. The research results provide a theoretical basis and reference for mastering the coupling mechanism between vertical vibration and pitching vibration and for the body vibration control.

Thermal comfort and energy performance improvement by optimization of shading devices using improved Battle Royal algorithm

SummaryChina's building energy consumption accounts for 27.5% of China's total energy demand. This amount is increasing because of the considerable increase in the rate of household equipment mostly in air‐conditioning systems. In this study, the TRNSYS simulation tool and improved Battle Royal optimizer (IBRO) is coupled for energy optimization of the building based on the simulation to study the impact of the overhangs optimization. The thermal comfort enhancement is evaluated in three case studies of three different weather conditions in China. To validate the achieved results, a comparison of the optimum values with benchmark cases is performed with consideration of heating and cooling demands, and yearly discomfort percentage. According to the achievements, an improvement can be seen in the comfort level. Also, the cooling demand is decreased by 4.2% for Shanghai.

A Differential Flatness-Based Model Predictive Control Strategy for a Nonlinear Quarter-Car Active Suspension System

Controlling an automotive suspension system using an actuator is a complex nonlinear problem that requires both fast and precise solutions in order to achieve optimal performance. In this work, the nonlinear model of a quarter-car active suspension is expressed in terms of a flat output and its derivatives in order to embed the nonlinearities of the system in the flat output. Afterward, a Model Predictive Controller based on the differential flatness derivation (MPC-DF) of the quarter-car is proposed in order to achieve optimal control performance in both passenger comfort and road holding without diminishing the lifespan of the wheel. This formulation results in a linear optimization problem while maintaining the nonlinear behavior of the active suspension system. Afterward, the optimization problem is solved by means of Quadratic Programming (QP), enabling real-time implementation. Simulation results are presented using a realistic road disturbance to show the effectiveness of the proposed control strategy.

A machine-learning-based event-triggered model predictive control for building energy management

Model predictive control (MPC) for building energy management has exhibited a huge potential for largely cutting down energy use and improving human comfort. However, the high demand for computational power for solving the optimization is challenging the widespread deployment of MPC in real buildings. Typical MPC employs a time-triggered mechanism (TTM) that runs optimization recurrently at each time step without considering the necessity, which could cause excessive computation resource usage. This paper proposes an event-triggered mechanism (ETM) that only runs optimization when triggering events occur. Contrary to conventional ETMs that only considers the current information (e.g., room conditions), the ETM proposed is based on a cost function that covers the past, current, and future information. Based on the proposed ETM, a machine-learning-based event-triggered model predictive control (ETMPC) system that optimizes both building energy efficiency and thermal comfort is developed. The developed ETMPC system is then employed for air-conditioning control for performance evaluation through simulations. The control performance of the proposed ETMPC is compared to an MPC employing TTM and a common thermostat. Compared to the MPC employing TTM, the proposed ETMPC reduced the computational load in terms of the number of optimization runs by 77.6%–88.2%, meanwhile, achieving similar energy savings (more than 9.3% energy saving over the thermostat) as the MPC employing TTM does (9% energy saving over the thermostat). With the significant reduction of computational load, the ETMPC achieves similar thermal comfort performance as the MPC employing TTM does, and it is significantly better over the thermostat.

Aerodynamic Characteristics and Dynamic Performance of the Moving Train Under Crosswind

The aerodynamic characteristics (research on the aerodynamic coefficients and surface pressure coefficients of trains at different wind yaw angles) and dynamic performance (research on the safety and comfort of train operation at different wind speeds and train speeds) of moving trains need to be explored to accurately evaluate their safety in a more realistic scenario. However, tests for a moving train model are costly and difficult to implement. In this paper, numerical simulations are conducted to investigate the aerodynamic characteristics and dynamic performance of moving and stationary trains. The surface pressure distribution and aerodynamic coefficients of the train are analyzed in detail. The results show that the three-component force coefficients of the stationary train are larger than those of the moving train when the wind yaw angle is less than 30°. At different train speeds and wind speeds, the running safety index based on the aerodynamic characteristics of the stationary train is larger (safer) than that of the moving train. However, the result of the comfort evaluation based on the aerodynamic characteristics of the stationary train may be too conservative. Moreover, the traditional formula is improved to more precisely predict the aerodynamic coefficients of the train within a wide range of wind yaw angles. Compared with the traditional formula, the improved formula only requires the three-component force coefficient of the vehicle at a 45° wind yaw angle, and the wind load of the train is independent of its speed. Hence, it is simpler and more convenient to calculate the wind load of the train. This work proves that it is feasible to estimate the aerodynamic force coefficients of moving trains by static wind tunnel tests combined with the improved formula.

Experimental evaluation of ride comfort performance for suspension system using PID and fuzzy logic controllers by advanced firefly algorithm

Experimental evaluation of ride comfort performance for suspension system using PID and fuzzy logic controllers by advanced firefly algorithm

Vibration Assessment of a 12-kW Self-Propelled Riding-Type Automatic Onion Transplanter for Transplanting Performance and Operator Comfort

Vibration assessment of upland crop machinery under development is essential because high vibrational exposures affect machine efficiency, service life of components, degradation of the working environment, and cause health risks to the operator. It is intensively assessed for automobiles as well as large off-road agricultural vehicles (i.e., tractors). However, it is mostly overlooked in the case of the small or medium riding-type upland utility vehicles. Therefore, the vibration exposures of a 12-kilowatt self-propelled riding-type automatic onion transplanter were measured and evaluated to assess the performance of onion transplantation and the operator’s comfort in this study. Different types of driving surfaces, operating statuses (static and driving), and load conditions were considered to analyze the vibration exposure. The precision of transplantations was evaluated while operating the transplanter on the soil surface with different driving speeds and load conditions. Tri-axial accelerometers and a LabVIEW-coded program were used for data acquisition. The vibrational exposures were evaluated based on ISO standards, and power spectral density (PSD) was estimated to assess the major frequencies. According to the statistical analysis, the daily exposure value (A(8)) and the vibration dose value (VDV) varied from 10 to 15 ms−2 and 20 to 31 ms−1.75, respectively, which exceeded the ISO 2631-1 standards (i.e., A(8): 1.15 ms−2 and VDV: 21 ms−1.75). The calculated health risk factor (RA) was moderate. Moreover, a high weighted acceleration (around 8 ms−2) was observed on the seedling conveyor belt, which might result in missing seedlings during transplanting. The vibration exposures of the developed onion transplanter need to be minimized following the ISO standards, and vibration reduction would also improve the market competitiveness.

Evaluation of Heated Window System to Enhance Indoor Thermal Comfort and Reduce Heating Demands Based on Simulation Analysis in South Korea

Heated glass can be applied to improve windows’ condensation resistance and indoor thermal comfort in buildings. Although this applied technology has advantages, there are still some concerns in practical applications, such as additional energy consumption and control issues. This study evaluates the effectiveness of a heated window heating (HWH) system in terms of thermal comfort and heating energy performance (HEP). The simulation-based analysis is performed to evaluate the effectiveness of the HWH using a residential building model and to compare it with radiant floor heating (RFH) and hybrid heating (HH) systems (i.e., combined HWH and RFH). This study also investigates the peak and cumulative heating loads using HWH systems with various scenarios of control methods and setpoint temperature. The predicted mean vote (PMV) is used as an indoor thermal comfort index. The ratio of cumulative thermal comfort time to the entire heating period is calculated. The results show that HWH and HH can reduce the heating load by up to 65.60% and 50.95%, respectively, compared to RFH. In addition, the times of thermal comfort can be increased by 12.55% and 6.98% with HWH and HH, respectively. However, considering the social practices of South Korea, HH is more suitable than HWH. Further investigations for HH show that a surface setpoint of 26 °C is proper, considering both heating demands and thermal comfort. In addition, the setpoint temperature should be determined considering HEP and the thermal comfort for HWH, and the optimal setpoint temperature was suggested under specific conditions.

Intelligent Road-Adaptive Semi-Active Suspension and Integrated Cruise Control

The availability of road and vehicle data enables the control of road vehicles to adapt for different road irregularities. Vision-based or stored road data inform the vehicle regarding the road ahead and surface conditions. Due to these abilities, the vehicle can be controlled efficiently to deal with different road irregularities in order to improve driving comfort and stability performances. The present paper proposes an integration method for an intelligent, road-adaptive, semi-active suspension control and cruise control system. The road-adaptive, semi-active suspension controller is designed through the linear parameter-varying (LPV) method, and road adaptation is performed with a road adaptivity algorithm that considers road irregularities and vehicle velocity. The road adaptivity algorithm calculates a dedicated scheduling variable that modifies the operating mode of the LPV controller. This modification of operation mode provides a trade-off between driving comfort and vehicle stability performances. Regarding the cruise control, the velocity design of the vehicle is based on the ISO 2631-1 standard, the created database, and the look-ahead road information. For each road irregularity, the velocity of the vehicle is designed according to previous measurements and the table of ISO 2631-1 standard. The comfort level must be selected in order to calculate dedicated velocity for road irregularity. The designed velocity is tracked by the velocity-tracking controller evaluated with the LPV control framework. The designed controllers are integrated, and the operation of the integrated method is validated in a TruckSim simulation environment.

Research on indoor thermal comfort and energy consumption of zero energy wooden structure buildings in severe cold zone

Indoor thermal comfort level not only affects the indoor thermal environment but also affects building energy consumption. Generally speaking, the higher the thermal comfort of the building, the greater its energy consumption. Therefore, in severe cold zone with the most stringent thermal engineering standards in China, how to reduce building energy consumption while improving building thermal comfort is of great significant for the building in this region to achieve zero energy consumption. In order to achieve this research goal, this paper designs two kinds of wooden structure buildings with water-passing wall in severe cold zone. Through combination of simulation and scale model experiments, the performance of water-passing wall, thermal comfort performance of wooden structure building, and building energy consumption were studied. The research results indicate that the water-passing wall of the wooden structure building has good thermal stability and thermal insulation performance, which can isolate outdoor cold in winter. Moreover, due to the function of water-passing wall, the two kinds of wooden structure buildings have high thermal comfort levels throughout the year, with occupants feeling uncomfortable for no more than 6% of the year. It is compared with the energy consumption before the water supplying to the wall, the total energy consumption of the two kinds of wooden structure buildings were reduced by 44.3% and 46.2% respectively. Therefore, these two kinds of wooden structure building can pursue higher thermal comfort with lower energy consumption, it has high energy-saving benefits.