Door Motion Research Articles

Numerical study of airflow pattern and bioaerosol dispersion during door motion in a negative pressure isolation ward

Negative pressure isolation wards are typically equipped with buffer rooms to prevent the spread of infectious bioaerosols into clean areas and facilitate timely removal. The opening and closing process of sliding doors is very common in wards. Since the air exchange characteristics of the doorway affect the risk of infection and the efficiency of particle removal within the buffer room, the boundary transformation method and dynamic numerical simulations are used to study the airflow patterns and particle diffusion during door motion. The corresponding cases for different pressure differences, temperature differences, and door motion modes are compared. The results indicate that under different temperature differences, the particles can be dispersed uniformly in a short time (about 23s), and there is no phenomenon of particle aggregation. Compared to the initial pressure difference, adjusting the initial temperature difference has a more pronounced effect on air infiltration and particle concentration trends. The peak particle concentrations within the buffer zone under negative temperature differences are on average 19.9 % higher compared to the positive temperature differences. However, particle concentrations at negative initial temperature differences decay more rapidly. It is found that by reducing the duration of full door opening from 6s to 2s, the time for particles to be completely removed can be reduced by 30.6 %. This study provides useful information for evaluating the risk of infection and developing operational modes of the buffer room.

Aerosol exchange between pressure-equilibrium rooms induced by door motion and human movement

It is now widely recognised that aerosol transport is major vector for transmission of diseases such as COVID-19, and quantification of aerosol transport in the built environment is critical to risk analysis and management. Understanding the effects of door motion and human movement on the dispersion of virus-laden aerosols under pressure-equilibrium conditions is of great significance to the evaluation of infection risks and development of mitigation strategies. This study uses novel numerical simulation techniques to quantify the impact of these motions upon aerosol transport and provides valuable insights into the wake dynamics of swinging doors and human movement. The results show that the wake flow of an opening swinging door delays aerosol escape, while that of a person walking out entrains aerosol out of the room. Aerosol escape caused by door motion mainly happens during the closing sequence which pushes the aerosols out. Parametric studies show that while an increased door swinging speed or human movement speed can enhance air exchange across the doorway, the cumulative aerosol exchange across the doorway is not clearly affected by the speeds.

Numerical study on transient airflows and air exchange induced by door motion in thermally stratified environment

Door motion has been identified as a contribution factor for containment transport between indoor and outdoor, but the combined airflow characteristics due to door motion, ventilation airflow and thermal effects have not been clarified. This paper investigated transient airflow characteristics and amount of air exchange induced by hinged door motions in thermally stratified environment with displacement ventilation using dynamic CFD simulation. The results show that about 40% amount of air exchange occurs in the first phase when door angle β < 30° although the consumed time is only 15% of the whole door motion process. Indoor and outdoor air temperature difference and rotation speed of the hinged door are two important influencing factors. When the door motion is slow enough and temperature difference is above 3 °C, the thermal convective flow could significantly affect the airflow pattern through the doorway. When there is no indoor and outdoor temperature difference, the amount of air exchange increases linearly with door motion speed. Under combined effects of buoyancy force and door motion, a moderate door speed results in minimum air exchange. The door motion only affects the air temperatures near the door. The overall thermal stratification in the displacement ventilated room is not significantly destroyed by a single door open and close cycle. The findings could provide suggestions for reducing door motion induced contaminant transport, and enhance understanding of dynamic disturbance effects in thermally stratified environments.

Comparison of Embedded Sensor Data for Long-Term Care Residents Before and After Onset of the COVID-19 Pandemic

Older adults have experienced greater isolation and mental health concerns during the COVID-19 pandemic. In long-term care (LTC) settings, residents have been particularly impacted due to strict lockdown policies. Little is known about how these policies have impacted older adults. This study leveraged existing research with embedded sensors installed in LTC settings, and analyzed sensor data of residents (N=30) two months pre/post the onset of the U.S. COVID-19 pandemic (1/13/20 to 3/13/20, 03/14/20 to 5/13/20). Data from three sensors (bed sensors, depth sensors, and motion sensors) were analyzed for each resident using paired t-tests, which generated information on the resident’s pulse, respiration, sleep, gait, and motion in entering/exiting their front door, living rooms, bedrooms, and bathrooms. A 14.4% decrease was observed in front door motion in the two months post-onset of the pandemic, as well as a 2.4% increase in average nighttime respiration, and a 7.6% increase in nighttime bed restlessness. Over half of our sample (68%) had significant differences (p<0.05) in restlessness. These results highlight the potential impact of the COVID-19 pandemic and social distancing policies on older adults living in LTC. While it is not surprising that significant differences were found in the front door motion sensor, the bed sensor data can potentially shed light on how sleep was impacted during this time. As older adults experienced additional mental health concerns during this time, their normal sleep patterns could have been affected. Implications could help inform LTC staff, healthcare providers, and self-management of health approaches among older adults.

Smart security door system using SMS based energy harvest

Over the last decade, different studies have been conducted to increase security to identify sensor technology and provide alternative energy with other energy harvest techniques such as vibration energy harvester and sun energy harvester. There is no combinational approach to utilize the door to create energy and use it for security measures in the literature, making our system different and unique. This proposed system comprises the security and the energy harvest; the security section utilizes a motion detector sensor to detect intruders. For instance, the magnetic door lock type firmly locks the door, which can only open with a generated password. On the other side, the energy harvest section utilizes the door motion to generate electricity for the system, which solves power shortage and limited battery life issues. Moreover, this study includes a GSM module that allows authorized owners to receive a generated password as a security enhancement. This design mainly focuses on improving or optimizing the conventional security doors' overall performance as sliding door, panel door, or revolving door. The experimental results show the system efficiency in terms of power generation and the time needed to authenticate the property owner. Notably, the power generator can generate electricity more rapidly, while the needed time to receive the mobile device's security code is around 3.6 seconds.

The effect of door opening on air-mixing in a positively pressurized room: Implications for operating room air management during the COVID outbreak

The effect of the built environment on the predominant indoor airflow patterns is significant. To protect the healthcare workers at the front line from the outbreak of COVID − 19, it is necessary to understand the transmission dynamics of the virus, which has been shown to depend on indoor airflow patterns. In hospital operating rooms (ORs), design requirements pose a unique challenge as the positive pressure in the OR can facilitate virus spread into adjacent spaces, shall a COVID-positive patient require a surgical procedure. Moreover, the turbulent vortexes from door motions could independently increase the probability of virus escape from the OR to the adjacent corridors. Therefore, to obtain critical knowledge about the alteration of flow fields due to door movement in a positively pressurized room and quantify the air mixing across the door, a series of experiments were conducted in a controlled chamber. The results demonstrate significant impacts of the door opening on the airflow patterns. Increased alterations near the door and vortexes penetrating far into the chamber with multiple doors openings warrant further study of the indoor airflow dynamic under door motion. This experimental study proposes an algorithm to quantify the air exchange due to a standard door opening and quantifies this exfiltration of contaminated air up to 2 air changes per hour, that is 10% of the chamber supply airflow rate. The algorithm to quantify the dissipated air quantity and the analyses of interaction between initial conditions and door openings contribute to the originality of this paper.

Simulation of the effect of floodway on Batang Kandis River flood control

Floods often occur in Padang City, mainly in the areas of Pasia Nan Tigo Village and Lubuk Buaya Village, caused by the overflow of Batang Kandis when heavy rains occur (intensity of rainfall >15mm/hours). To decrease the river overflow an artificial canal with 300 m long and 50 m wide (floodway) was constructed to bypassing the river flow from the Batang Kandis River to the ocean. In order to find out the effects of the floodway, four scenarios are performed the scenario 1 and 2 were the simulation condition of Batang Kandis River before and after the construction of floodway. While to increase the effectiveness of floodway, simulations 3 and 4 were carried out. Scenario 3 was the combination of floodway with normalization and embankment. To prevent the entry of seawater into the Batang Kandis River, because the floodway is affected by the tide of the sea, then 3-door motion weir was simulated namely scenario 4. Scenario 4 was the combination of floodway normalization, embankment, and a 3 door motion weir. From the simulations, we found that the floodway was effective to decrease the water surface level up to 15 m and 20 m during 10 years and 25 year return period of discharge respectively. From the scenario 3, we found that the embankment with 1.5 m and 2 m was effective to prevent overflow by 10-year and 25-year return period of discharge respectively. While for scenario 4 the water level rises 0.5 m due to motion weir So, that it is needed to extend the embankment with 0,5m high.

Analysis of technical and operational characteristics of turning-and-shunting door opening mechanism of electric public transport

One of the most important problems occurring while designing public transport vehicles consists in providing an effective control of the door opening systems. The methods of carrying out the investigations presented in the paper include structural and kinematic analysis of the door opening mechanisms and simulation of their operation in applied software. The paper analyses the design and operational peculiarities of the turning-and-shunting mechanism of door opening of electric public transport. The corresponding design of the mechanism is proposed. It is suggested to be driven by pneumatic drive. The simplified diagram of the mechanism is constructed. Structural and kinematic analysis of the mechanism is performed, and the analytical dependencies for describing the motion of its links during the door opening/closing are derived. The main kinematic parameters of the studied mechanism are investigated on the basis of the derived analytical dependencies in MathCAD software, as well as by means of simulating the motion of the solid-state model of the mechanism designed in SolidWorks software. The conclusions about the agreement of the results of theoretical investigations performed on the basis of numerical solving the obtained motion equations and of the virtual experiment (motion simulation in SolidWorks software) are drawn. The analysis of energy efficiency of the investigated turning-and-shunting door opening mechanism of electric public transport is carried out. Prescribing the resistance force acting on the door leaf and calculating the corresponding door motion speed during its closing, the dependency of the nominal power supply of the mechanism drive as a function of corresponding generalized coordinates was deduced. Analyzing the obtained results, the authors have established that the necessary nominal power of the turning-and-shunting mechanism drive is almost twice larger than the necessary nominal power of the widely used leaning-and-shunting mechanism. Further investigations on the subject of the paper can be performed in the direction of developing different control systems providing safe and reliable operation of the considered door opening mechanism driven be electric and pneumatic actuators.

An observational study of door motion in operating rooms

Door openings have been shown to increase bacterial counts in the operating room (OR) as a result of air exchange between the OR and adjacent spaces, potentially increasing risks for Surgical Site Infections (SSIs). A deeper understanding of door opening behavior and patterns is necessary to develop interventions that will have sustained impacts. Twenty-eight surgical procedures were recorded and closely watched. Accordingly, duration, intent, and destination of people involved in all door openings were identified and analyzed with respect to operation phase (i.e., pre-incision, incision-to-closure, and post-closure phases). Results suggest that the distribution of door opening duration in the incision-to-closure phase is independent of surgery type and room layout. The door was opened by someone other than the core surgical staff around 23% of the time. There seems to be a need for improvement in communication and design efficiency to manage traffic through the OR door.

Renovation in hospitals: a case study of source control ventilation in work zones

ABSTRACTApproximately half of the nosocomial aspergillosis outbreaks in hospitals have been associated with renovation activities. When disturbed, spores encapsulated in building materials can be aerosolized and transported throughout the healthcare facility causing potentially fatal complications, particularly among elderly and immunocompromised patients. Thus, a series of experiments were conducted in an actual hospital to observe containment and removal of airborne particulates with respect to ventilation arrangement and directional airflow. Computational models were then developed to further study the spread of contamination during a hospital renovation project. Results of this study suggest that although directional airflow (negative pressure) was effective in containing particulates across an open doorway between patient and contaminated spaces, turbulence caused by door motion and the location of the exhaust grilles affected the transport of particulates in the work zone. A new source-control ventilation strategy is proposed where the arrangement of supply and exhaust air ventilation is optimized to more effectively contain and remove airborne particulates within hospital work zones. Results indicate that the location of supply and exhaust air relative to the contaminant source can increase particulate removal by an additional 26%, or roughly the effect of doubling work zone air changes – without added operations and maintenance (O&M) costs.

バイオクリーン施設への安全キャビネットの適用に関する研究 （その2）空調気流や扉開閉で生じる気流が安全キャビネット内部の清浄度に及ぼす影響

バイオクリーン施設への安全キャビネットの適用に関する研究 （その2）空調気流や扉開閉で生じる気流が安全キャビネット内部の清浄度に及ぼす影響

An experimental study of the flow induced by the motion of a hinged door separating two rooms

The indoor air flow and mass exchange induced by the rotating motion of a hinged door separating two rooms is investigated. Experiments were conducted in a scale model based on Reynolds number matching. Flow visualisations show the transport mechanism associated with the open and close phases of the door motion. In the room into which the door is opened a large-scale vortex is formed during opening, which is advected along the walls. In the adjacent room, a volume of fluid spreads both longitudinally and transversely. Concentration measurements were carried out to quantify the mass exchange generated by these flow patterns. Results are presented in dimensionless form for the volume of fluid exchanged and are compared to earlier data. The effects of hold open time and door speed on the exchanged fluid volume are investigated. The exchange volume increases with hold open time, but it does not vary considerably with door speed for a constant hold open time. Further, three-dimensional velocity measurements were carried out near the doorway and the characteristics of the velocity field developed are also presented.

Large-eddy simulation of the containment failure in isolation rooms with a sliding door-An experimental and modelling study.

In hospital isolation rooms, door operation can lead to containment failures and airborne pathogen dispersal into the surrounding spaces. Sliding doors can reduce the containment failure arising from the door motion induced airflows, as compared to the hinged doors that are typically used in healthcare facilities. Such airflow leakage can be measured quantitatively using tracer gas techniques, but detailed observation of the turbulent flow features is very difficult. However, a comprehensive understanding of these flows is important when designing doors to further reduce such containment failures. Experiments and Computational Fluid Dynamics (CFD) modelling, by using Large-Eddy Simulation (LES) flow solver, were used to study airflow patterns in a full-scale mock-up, consisting of a sliding door separating two identical rooms (i.e. one isolation room attached to an antechamber). A single sliding door open/ hold-open/ closing cycle was studied. Additional variables included human passage through the doorway and imposing a temperature difference between the two rooms. The general structures of computationally-simulated flow features were validated by comparing the results to smoke visualizations of identical full-scale experimental set-ups. It was found that without passage the air volume leakage across the doorway was first dominated by vortex shedding in the wake of the door, but during a prolonged hold-open period a possible temperature difference soon became the predominant driving force. Passage generates a short and powerful pulse of leakage flow rate even if the walker stops to wait for the door to open.Electronic Supplementary Material (ESM):supplementary material is available in the online version of this article at 10.1007/s12273-017-0422-8.

Development of Simulator and Robotic Door for Parametric Design Optimization of Washing Machine Door Motion

Development of Simulator and Robotic Door for Parametric Design Optimization of Washing Machine Door Motion

Airflow patterns due to door motion and pressurization in hospital isolation rooms

Certain pathogens are transmitted through air by respiratory droplets that desiccate shortly after emission and form droplet nuclei (Nicas et al. 2005). Droplet nuclei are sufficiently small (<5.0 μm) to remain suspended in air indefinitely and, thus, create a pathway between an infected and susceptible person (Sehulster et al. 2003). This process is called “airborne transmission.” Patients with an airborne infectious disease (e.g., measles, SARS, tuberculosis, varicella, etc.) are isolated from the healthcare environment in an airborne infection isolation room to protect other patients and healthcare workers. These rooms have special features to effectively contain and remove airborne pathogens. For example, a 2.5-Pa negative pressure relationship with adjoining spaces is required for an airborne infection isolation room to create directional airflow into the room and prevent the transmission of airborne pathogens from the airborne infection isolation room to adjacent healthcare spaces. Directional airflow, however, may be disrupted and even reversed by door-opening motion and the movement of people and equipment into and out of the airborne infection isolation room. This article highlights the results of both experimental and computation studies that explore air exchange and particle movement between an isolation room and anteroom relative to 3-, 5-, and 7-s door cycle speeds and between neutral and negative air pressure relationships.

Experimental and Modelling Investigations of Air Exchange and Infection Transfer due to Hinged-Door Motion in Office and Hospital Settings

Occupants spend a significant amount of time indoors where temperature and air quality has an important impact on their comfort, health and work performance. Understanding the role of airflow exchange between spaces is crucial to describe the processes of mixing and transport of substances driven by air motion and therefore essential for evaluating indoor air quality. This work presents the results of field measurements and laboratory experiments designed to characterise door operation and to quantify its influence on air volumes exchanged between rooms due to door motion. The field study was conducted to identify typical total door cycle times in single person offices. The laboratory experiments were conducted in a scale model to investigate the exchange flow between two generic rooms. The model consisted of a water filled tank divided into two equal rooms, which were connected by a computer-controlled hinged door. Flow visualisations were used to describe flow patterns and concentration measurements of Rhodamine WT were performed to quantify exchange volumes. With hold open times of between 0s and 26.67s the total fluid volume exchanged was found to be between 67% and 98% of the total volume swept. Based on the exchange volume found in these experiments combined with the Wells-Riley equation the effect of ventilation rate on the probability of occupants in an adjacent room becoming infected was investigated. With ventilation rates for a medium air quality the risk of infection is low (<0.05). However, the probability of infection quickly rises with lower ventilation rates.

A wrench in the works of human acetylcholinesterase: soman induced conformational changes revealed by molecular dynamics simulations.

Irreversible inactivation of human acetylcholinesterase (hAChE) by organophosphorous pesticides (OPs) and chemical weapon agents (CWA) has severe morbidity and mortality consequences. We present data from quantum mechanics/molecular mechanics (QM/MM) and 80 classical molecular dynamics (MD) simulations of the apo and soman-adducted forms of hAChE to investigate the effects on the dynamics and protein structure when the catalytic Serine 203 is phosphonylated. We find that the soman phosphonylation of the active site Ser203 follows a water assisted addition-elimination mechanism with the elimination of the fluoride ion being the highest energy barrier at 6.5 kcal/mole. We observe soman-dependent changes in backbone and sidechain motions compared to the apo form of the protein. These alterations restrict the soman-adducted hAChE to a structural state that is primed for the soman adduct to be cleaved and removed from the active site. The altered motions and resulting structures provide alternative pathways into and out of the hAChE active site. In the soman-adducted protein both side and back door pathways are viable for soman adduct access. Correlation analysis of the apo and soman adducted MD trajectories shows that the correlation of gorge entrance and back door motion is disrupted when hAChE is adducted. This supports the hypothesis that substrate and product can use two different pathways as entry and exit sites in the apo form of the protein. These alternative pathways have important implications for the rational design of medical countermeasures.

Potential airborne transmission between two isolation cubicles through a shared anteroom

Full-scale experiments and CFD simulations were performed to study potential inter-cubicle airborne transmissions through a shared anteroom due to the hinged door opening. When doors are closed, current negative pressure designs are effective for the containment of airborne pathogens in the 'dirty' cubicle with an index patient. When the 'dirty' cubicle door is open, airborne agents can move into the other 'clean' cubicle via the shared anteroom. As the door being opened or closed, the door sweeping effect is the main source of the two-way airflow and contaminant exchange through the doorway. When the dirty cubicle door remains fully open, temperature difference and concentration gradient across the doorway induce the two-way buoyancy-driven flow and transport of airborne agents across the doorway. The longer the dirty cubicle door remains fully open (10 s, 30 s or 60 s) or the smaller the air change rate (34–8.5 ACH for each cubicle), the more airborne pathogens are being transported into the 'clean' cubicle and the longer time it takes to remove them after the door is closed. Keeping the door completely open is potentially responsible for the majority of inter-cubicle transmissions if its duration is much longer than the duration of door motion (only 3 s). Our analyses suggest a potential inter-cubicle infection risk if the shared anteroom is used for multiple isolation cubicles. Decreasing the duration of door opening, raising air change rate or using a curtain at the doorway are recommended to reduce inter-cubicle exposure hazards.

Magnetorheological Actuators with Currentless Bias Torque for Automotive Applications

The control of door motion in automotive applications often requires a bias torque to retain an actuator mechanism in a certain position without supplying power. Therefore, two magnetorheological actuators based on magnetorheological fluids with different kinds of magnetic excitation are developed. For the currentless bias torque generation, the first approach uses permanent magnets and offers an almost linear torque characteristic, while the second actuator design utilizes hysteresis properties of magnetizable materials resulting in an ambiguous control characteristic. The main advantage of the hysteresis-based magnetorheological actuator is an optimized design with respect to space and weight. But the hysteresis phenomenon has to be compensated by appropriate control algorithms, in order to obtain a linearized torque characteristic as investigated for actuated car doors with haptic capabilities (door assistant), such as for assisted egress or obstacle avoidance.

104 エレベーターのかご扉引き込まれ検出装置の開発

About 50% of the accidents that involves passengers happen near the door. Each elevator company has taken measures to prevent children's hands from getting pinched in the door. Today, a popular method is to stop the door motion when it detects a signal. However, OTIS's method is to prevent the accidents. It is to stop the door motion when the hands are sucked. It detects the trouble when the accident is about to happen. We have established the product performance and evaluation method to prevent the accidents and to secure safety. We have developed two devices. One is a "Mechanical" device using a micro switch and the other is an "Optical" device that detects change of light beam. We have made test pieces based on physical characteristic data of human body, and evaluated the device.