Environmental Control System Research Articles

The characteristics of particulate matter in different subway station environmental control systems

Particulate matter (PM2.5, PM10) in urban subway stations can significantly impact passengers' health. The particle concentration in subway stations is influenced by many factors. However, few existing studies have explored the impact of environmental control systems in-depth, especially under different outdoor pollution conditions. To address this research gap, this study focused on measuring and comparing the characteristics of PM2.5 and PM10 at subway stations with three control systems (open, closed, and screen door) under varying pollution conditions in Beijing. Particle concentrations from platforms, carriages, and outdoors were monitored and analyzed using statistical methods. The results showed that the particle concentration in the closed system was generally 20–40 μg/m3 higher than that in the screen system at the platform, which might be attributed to the piston wind, as the air from the tunnel with a lot of dirt. The pollution in the carriage was more severe for the open system than that of the screen system. The PM2.5/PM10 ratio in the carriage was 91%, 90%, and 83.84% for the closed, open, and screen systems, respectively. This indicates that the screen door could reduce the particle concentration in the platform to 10%–50%. The particle concentration varied among subway stations with different environmental control systems, suggesting that the prevention and control strategies for particulate matter pollution should be different for stations with different systems.

Investigation of Droplet Dynamics Under Shear Flow

The dynamics of droplet under shear flow was investigated in normal gravity and microgravity. Drop under shear flow has many applications in aerospace such as aircraft de-icing and environmental control and life support system in space station. Shape analysis of the droplet showed that drop in microgravity have a greater contact angle and height, but a smaller contact radius, than that in normal gravity. The difference between advancing and receding contact angle θa-θr is greater in microgravity than that in normal gravity under the same wind speed. The effect of airflow on the droplet is mainly dependent on the We number and the dimensionless number k′, which characterizes the ratio of wind force and adhesion force. the k’ in microgravity is larger than that in normal gravity. The droplet exposed to airflow from static to motion state can be divided into three regimes.

Research progress in biological control of tomato bacterial wilt.

Bacterial wilt caused by the infection of Ralstonia solanacearum, is one of the most harmful diseases to tomatoes, one of the most important greenhouse vegetables in China. R. solanacearum can survive and remain active in the deep soil for a long time, and the chemical control of tomato bacterial wilt is consequently limited. In this study, we introduced the characteristics of tomato bacterial wilt disease and the types of R. solanacearum, and systematically reviewed the research progresses of biological control methods from the aspects of botanical insecticides, agricultural antibiotics, biocontrol bacteria. We emphatically introduced the principle and current status of these methods, discussed the limitations and the improvement strategies, and prospected a new environmental protection and efficient biological control system based on micro-ecological regulation would be the development direction of biological control of tomato bacterial wilt.

(Invited) Leveraging Magnetohydrodynamic Mechanisms for Stable and Efficient Microgravity Electrolysis

Water electrolysis is the fundamental chemical process for oxygen and hydrogen production in space. It is widely employed in modern environmental control and life support systems, propulsion technologies, and high-density energy storage devices. Furthermore, future interplanetary missions are likely to employ water as a commodity acquired and processed by In Situ Resource Utilization (ISRU) methodologies to produce propellants, thereby reducing vehicle launch mass.The absence of buoyancy results in major technical challenges for the operation of electrolytic cells in low gravity. The need to detach and collect oxygen and hydrogen bubbles has been traditionally addressed by means of forced water recirculation loops. However, this leads to complex, inefficient, and unreliable liquid management devices composed of multiple elements and moving parts. Two distinct magnetohydrodynamic (MHD) mechanisms may instead be employed to induce phase separation: diamagnetic, and Lorentz forces. The former arises in the presence of strong, inhomogeneous magnetic fields and results in a magnetic buoyancy effect. The latter is a consequence of the imposition of a magnetic field to the current generated between two electrodes. Both approaches can potentially lead to a new generation of electrolytic cells with minimum or no moving parts, hence enabling the human deep space operations with minimum mass and power penalties.Dedicated microgravity experiments are required to study these novel magnetically enhanced electrolysis concepts. This presentation introduces the fundamentals of both methods and discusses the experimental design and results from several experimental campaigns at ZARM’s drop tower and Blue Origin’s New Shepard. The performance of representative electrolytic cells subject to different MHD regimes is addressed from an electrochemical and fluid dynamic perspectives. It is demonstrated that the MHD force effectively detaches and collects gas bubbles in microgravity while increasing the current density and improving the stability of the electrolytic cell. Ultimately, this opens the door for the development of highly-efficient space electrolytic cells with applications to human and robotic space exploration.

Integrated design optimization method for novel vapour-compression-cycle-based environmental control systems

The aircraft Environmental Control System (ECS) is the primary consumer of non-propulsive power at cruise conditions, hence, its performance optimization is crucial for the reduction of specific fuel consumption. A novel integrated system design optimization method is presented: thermodynamic cycle, component sizing and working fluid are taken into account simultaneously. This method was applied to the ECS of large rotorcraft based on a Vapour Compression Cycle system electrically driven by a high-speed centrifugal compressor. Steady-state and lumped parameter system component models have been developed using the Modelica acausal modelling language. The optimization design framework consists of an in-house code, featuring a Python-Modelica interface. The study case refers to a critical operating condition: the helicopter is on the ground during a hot and humid day. The working fluid is R-134a. The multi-objective optimization targets the maximization of the system efficiency and the minimization of system weight. The results show that more efficient systems can be designed only with heavier components. The design feasibility of high-speed centrifugal compressors is demonstrated. The advantage of an integrated system design optimization framework for complex energy systems is proved, allowing for the analysis of the impact of both component design and working fluid on system performance.

Stable Fiber-illumination for Extremely Precise Radial Velocities with NEID

NEID is a high-resolution red–optical precision radial velocity (RV) spectrograph recently commissioned at the WIYN 3.5 m telescope at Kitt Peak National Observatory, Arizona, USA. NEID has an extremely stable environmental control system, and spans a wavelength range of 380–930 nm with two observing modes: a High Resolution mode at R ∼ 112,000 for maximum RV precision, and a High Efficiency mode at R ∼ 72,000 for faint targets. In this paper we present a detailed description of the components of NEID’s optical fiber feed, which include the instrument, exposure meter, calibration system, and telescope fibers. Many parts of the optical fiber feed can lead to uncalibratable RV errors, which cannot be corrected for using a stable wavelength reference source. We show how these errors directly cascade down to performance requirements on the fiber feed and the scrambling system. We detail the design, assembly, and testing of each component. Designed and built from the bottom-up with a single-visit instrument precision requirement of 27 cm s−1, close attention is paid to the error contribution from each NEID subsystem. Finally, we include the lab and on-sky tests performed during instrument commissioning to test the illumination stability, and discuss the path to achieving the instrumental stability required to search for a true Earth twin around a solar-type star.

Analytical Model for Sparing Policy Analysis and Optimization for Space Habitat Operations

The inclusion of operational sparing policies in early system definition can ensure that spares’ allocations can optimally meet desired system reliabilities consistent with the planned maintenance of a crewed vehicle. This approach is critical for long-duration crewed missions where mass allocations are constrained and lack of safe abort contingencies limit options in the event of significant system degradation, especially in the environmental control and life support systems. This paper presents an analytical model for analyzing and optimizing sparing policies as part of an overall evaluation of the probability of sufficiency for a system configuration. The repair transition parameters are varied to change the state visitation probabilities that drive a change in the probability of sufficiency observed for a given mass allocation. These parameters are optimized using a particle swarm optimizer to identify the preferred strategy for a desired allocation mass.

All Electric Cooling System for Unmanned Aircrafts

This study brings out two All Electric Environmental Control System (AE-ECS) configurations for Unmanned Aircraft air-conditioning and performance evaluation of these two configurations interms of power consumption and fuel mass penalty. In conventional (or traditional) Bleed Air System, hot air is extracted from the engine compressor whereas in Bleed less Air Cycle system/Bleed less Vapour Cycle Systems (also called AE-ECS) bleed air extraction from engine is eliminated. Eliminating the extraction of bleed air from the engine in both the systems of Bleed less Air Cycle and Vapour Cycle System, saves the engine energy and thus increases the engine efficiency/thrust. In the present study performance of the Bleed less Air Cycle and Vapour Cycle systems are studied for typical flight envelop and heat loads of 5 kW. Bleed less Vapour Cycle System consumed less electric power compared to Bleed less Air Cycle System when compared for 5 kW cooling system requirements for an Unmanned Aircraft system. Fuel mass penalties are also calculated and compared for these two system configurations.

Sweat Production During Continuous and Interval Aerobic Exercise

INTRODUCTION:Aerobic exercise within the habitable volume of small spacecraft needed for space exploration beyond low Earth orbit is expected to challenge the capacity of environmental control systems. Moisture control is a primary concern. Crewmembers will contribute moisture to the cabin environment in the form of sweat while exercising. The effects of continuous aerobic exercise for improving and maintaining aerobic capacity is well characterized. Likewise, evidence suggests that high intensity interval exercise for shorter durations is also effective in building and maintaining aerobic capacity. METHODS: On separate days, measures of sweat and respiratory responses were made for continuous (30 min of steady state exercise at ∼75% of aerobic capacity) and two interval (4 × 4 min, 8 × 30 s) exercise protocols. RESULTS: We observed that the 4-min and 30-s interval protocols produce 16% and 66% less metabolic water loss vs. the continuous exercise protocol, respectively. These responses were highly correlated with the amount of work performed (R2 = 0.81) and the amount of energy expenditure (R2 = 0.83) during exercise. DISCUSSION: These results suggest that interval exercise may be a useful alternative to continuous aerobic exercise when metabolic water production is an environmental concern. The results may inform the choices of aerobic exercise countermeasure protocols for use in deep space exploration. Ryder JW, Crowell JB, Song HJ, Ewert M. Sweat production during continuous and interval aerobic exercise. Aerosp Med Hum Perform. 2023; 94(8):623–628.

Thermodynamic Analysis of Vapor Compression Refrigeration System for Aircraft with Refrigerant R134a

The Environmental Control System (ECS) for a typical fighter aircraft is used for cabin cooling and pressurization, demisting operations, and for avionics cooling. Most of the passenger and fighter aircrafts use Bleed-Air Cycle for ECS. In this paper a new ECS called All Electric Environmental Control System (AEECS) is presented which works on Vapor Compression Refrigeration System using ram air as medium. It is called a power optimized system. The sizing of the system is based on the heat load calculations of the cabin and avionics for different flight conditions. A generalized software program is developed for evaluating system performance which includes key results regarding air compressor capacity, thermodynamic properties of refrigerants and Vapor Compression Refrigeration System. The AEECS is found to reduce the power requirement of the system to 80 kW compared to the Bleed Air Cycle ECS which requires a power of 0.8 MW to run the system. The results are presented in the form of graphs.

Design of a Closed Piggery Environmental Monitoring and Control System Based on a Track Inspection Robot

To improve environmental quality in enclosed piggeries, a monitoring and control system was designed based on a track inspection robot. The system includes a track mobile monitoring platform, an environmental control system, and a monitor terminal. The track mobile monitoring platform consists of three main components: a single-track motion device, a main box containing electronic components, and an environmental sampling device. It is capable of detecting various environmental parameters such as temperature, humidity, NH3 concentration, CO2 concentration, light intensity, H2S concentration, dust concentration, and wind speed at different heights below the track. Additionally, it can control on-site environmental control equipment such as lighting systems, ventilation systems, temperature control systems, and manure cleaning systems. The networked terminal devices enable real-time monitoring of field equipment operating status. An adaptive fuzzy PID control algorithm is embedded in the system to regulate the temperature of the piggery. Field tests conducted on a closed nursery piggery revealed that the system effectively controlled the maximum temperature range within 2 °C. The concentrations of CO2, NH3, and PM2.5 were maintained at a maximum of 1092 mg∙m−3, 16.8 mg∙m−3, and 35 μg∙m−3, respectively. The light intensity ranged from 51 to 57 Lux, while the wind speed remained stable at approximately 0.35 m∙s−1. The H2S concentration was significantly lower than the standard value, and the lowest relative humidity recorded was 18% RH at high temperatures. Regular humidification is required in closed piggeries and other breeding places when the system does not trigger the wet curtain humidification and cooling function, as the relative humidity is lower than the standard value. By controlling the temperature, the system combined with a humidification device can meet environmental requirements. The control method is simple and effective, with a wide range of applications, and holds great potential in the field of agricultural environmental control.

Effects of environmental control and LED supplemental lighting on strawberry growth and yield in a subtropical climate

We investigated the effects of environmental control and daytime LED supplemental lighting on the growth and yield of strawberries in a subtropical climate. Two strawberry cultivars, namely ‘Yotsuboshi’ and ‘Benihoppe’, were grown in three greenhouses from October to May as a forcing culture: (1) conventional greenhouse, with side vents open and no other environmental controls; (2) controlled environment (CE) greenhouse, equipped with an integrated environmental control system to cool air and growing medium using cooling devices controlled by sensor monitoring; and (3) LED greenhouse, equipped with an integrated environmental control system and LED supplemental lighting during the day. The conventional greenhouse had higher air and growing medium temperatures during the growing season than the CE or LED treatment greenhouse. Both cultivars had significantly lower aboveground dry-matter weight (TDM) and yield in the conventional treatment than in the CE or LED treatment. Yield in the CE treatment increased 2.4 and 2.0 times for ‘Yotsuboshi’ and ‘Benihoppe,’ respectively, relative to the conventional treatment. Additionally, yield in the LED treatment increased 3.1 and 2.5 times for ‘Yotsuboshi’ and ‘Benihoppe,’ respectively, relative to the conventional treatment. The marketable fruit ratio was higher in CE and LED treatments than in the conventional treatment for both cultivars. The number of fruits for both cultivars was significantly greater under the LED treatment than the conventional treatment. Clearly, daytime LED supplemental lighting further improved TDM and yield during the winter season, when cloudy weather and low solar radiation were persistent. However, during the spring season, when external solar radiation exceeded 20 MJ m−2 day−1, the enhancing effects of LED supplemental lighting on yield were limited. Supplemental lighting methods based on the amount of solar radiation available are necessary to allow maximum, high-quality strawberry fruit production in subtropical regions.

The Measuring of the Strategical Business Management in the Real Estate Agency Industry in Beijing, China

Background and Aim: China's economic reforms cause uncertainty, decelerating output, investment, and employment rates, with the real estate sector being the primary focus. This research aims to measure the opinion level of strategic business management in the Real Estate Agency Industry in Beijing, China, and to study the guideline for improving strategic business management in the Real Estate Agency Industry in Beijing, China. Materials and Methods: This research paper observes the quantitative research methodology. The study will encompass a total of 45 firms operating in the real estate agency industry in Beijing. The present study utilized a questionnaire as a data collection tool. The statistical parameters, including the mean and standard deviation, were employed for the purpose of data analysis and to ascertain the data presented. Results: The Beijing real estate agency industry has moderate opinions on strategic management, with moderate scores in evaluation and control, implementation, formulation, and environmental scanning. The study aims to improve strategic business management, focusing on environmental scanning, mission statement, objectives, processes, and control systems. Conclusion: Beijing real estate agency industry moderates strategic management, focusing on environmental scanning, mission statement, objectives, processes, and control systems. The business strategical management data promotes innovation and communication through compliments and awards. Internal procedures should focus on improving customer service and employee skills, even if data shows business performance is good.

A feedback control method for plant factory environment based on photosynthetic rate prediction model

In facility agriculture, environmental parameters are usually associated, uncertain and fluctuating. In the existing environmental control system, environmental parameters are regulated according to human experience, and the feedback control of environment and equipment energy consumption are not considered enough. It is of great significance to study an environmental optimization control system that can not only realize the feedback control of greenhouse climate but also reduce energy consumption, which can improve yield and reduce regulation cost. To this end, a feedback control system for plant factory environment based on photosynthetic rate prediction model is proposed in this paper. The system is composed of a master node and multiple sub-nodes. Firstly, low-power wide area network (LPWAN) technology is used to build a multi-network structure to achieve monitoring area network coverage. The master node is compatible with ZigBee, LoRa and Cat.1 communication technologies. Depending on the communication distance, ZigBee or LoRa communication technology is used for data transmission of the sub-nodes. Secondly, the photosynthetic rate prediction model was established by the least squares support vector machine (LSSVM) algorithm. Finally, the optimal control strategy for the plant factory environment was developed by integrating the multi-objective compatible control (MOCC) algorithm with a photosynthetic rate prediction model. The experimental results show that the coefficient of determination (R2) of the prediction model is 0.992. In the optimal control condition, the average leaf temperature was 27.55℃, the average CO2 concentration was 1214.20µmolmol−1, and the average PPFD was 1709.51µmolm−2s−1.

Development of a Novel Ground Test Facility for Aircraft Environmental Control System

Abstract In this article, the development and experimental investigation of a Boeing 737 aircraft environmental control system (ECS) passenger air conditioner (PACK) has been reported. The PACK is the heart of the ECS that conditions bleed air prior to supplying it to the cabin and avionics bay. Its capability to mask fault occurrences has resulted in increased unscheduled maintenance of the system. As such it has been a key research topic to understand PACK performance characteristics in order to support an accurate diagnostic solution. This article is a continuation of the authors’ work on the development of a systematically derived PACK simulation model and reports the overall development and qualification of a novel in situ ground test facility (GTF) for the experimental investigation of a B737-400 aircraft PACK under various operating modes, including the effect of trim air system. The developed GTF enables the acquisition of the temperature, pressure, and mass flow data throughout the PACK. The overall process of instrumentation selection, installation, sensor uncertainty, and testing in terms of data repeatability and consistency has been reported. The acquired data are then employed to conduct verification and validation of the SESAC (simscape ECS simulation under all conditions) simulation framework. The reported research work therefore enables the advancement in the level of scientific understanding corresponding to the ECS PACK operation under real operating conditions, and therefore supports the development of a robust simulation framework for ECS fault diagnostics at the system level.

Genome Sequences of Bacteria Isolated from the International Space Station Water Systems.

We report draft genomes of five bacteria recovered from the U.S. and Russian water systems onboard the International Space Station. The five genera include Ralstonia, Burkholderia, Cupriavidus, Methylobacterium, and Pseudomonas. These sequences will help further the understanding of water reclamation and environmental control and life support systems in space.

Environmental Management Control Systems and Environmental Performance: Direct and Indirect Effect

Purpose: This study aims to examine the effect of environmental management control systems on environmental performance. Testing is carried out directly or through the environmental strategy mediation role. Theoretical framework: In contrast to previous studies, this research focuses on managerial activity processes that enable, encourage, ensure how a company and facilitate practices that achieve environmental performance and strategies to achieve it. The research model is built on the basis of stakeholder theory and contingency theory. Design/methodology/approach: The research was conducted through an online survey of hotel managers in Makassar City, Indonesia. Data analysis was performed by regression, path analysis and Sobel test. Findings: The results of the study prove that the environmental management control system has a positive and significant effect on environmental strategy and environmental performance. The Sobel test also proves that environmental strategy mediates the influence of environmental management control systems on environmental performance. Research, Practical & Social implications: This research covers hotels in Makassar, not all of them in Indonesia; therefore, generalizing the findings of this study should be exercised with caution. Secondly, this study assumes hotel homogeneity and does not consider hotel type. The findings of this study also provide recommendations on public policy and business practices to integrate environmental issues into managerial processes and decision-making as well as corporate control. Further research can expand this research by considering contextual and other contingency aspects. In addition, future research may use a larger sample and longitudinal data which allows to investigate changes in strategic environmental management control system policies over time. Originality/value: Improvements in research on environmental management control systems have become a very important issue in supporting the themes of sustainability in business practices globally. The originality of this research focuses on managerial processes to support sustainability practices in business, especially business practices in hotels.

A multi-agent flocking collaborative control method for stochastic dynamic environment via graph attention autoencoder based reinforcement learning

The environmental adaptability of the multi-agent flocking collaborative control system is vital to practical applications. Focusing on the adaptive problem of multi-agent flocking collaborative control system in stochastic dynamic environment, this paper proposes a distributed multi-agent flocking collaborative control algorithm based on a graph attention autoencoder (GAE) based multi-agent reinforcement learning (MARL). In our algorithm, a distance-based graph attention (GAT) mechanism is introduced into the networks of MARL to improve the non-stationarity problem of state transition in MARL caused by stochastic dynamic environment and enhance agents’ comprehension to the observation state. Based on the distance-based GAT, a GAE is designed to adapt to dynamic scale scenes. In addition, a global reward based strategy evaluation method is used to minimize the system loss of the flocking collaborative control system. The experimental results demonstrate that the proposed flocking algorithm has better environmental adaptability and better global control strategy than other RL-based flocking algorithms. The conclusion that the control strategies learned by our algorithm can be well transferred to the scenes with different agents and obstacles is also verified. This paper provides a novel and effective solution scheme to the multi-agent flocking collaborative control problem in a stochastic dynamic environment, which is conducive to promoting the application of flocking algorithm.

Unveiling the Internet of Things (IoT) Applications in Aquaculture: A Survey and Prototype Design with ThingSpeak Analytics

The study examines the potential impact of IoT in aquaculture, and its role in enhancing water quality monitoring as well as the disease prevention. It highlights the transformative power of IoT technology in providing real-time data on water parameters and enabling proactive measures against diseases. The study emphasizes the significance of adopting IoT solutions to optimize water conditions, mitigate disease risks, and enhance fish health. It also explores recent advancements, key challenges, and future directions in IoT applications for aquaculture, including water quality monitoring, feed automation systems, environmental control systems, fish tracking and monitoring systems, remote monitoring and control systems, smart harvesting systems, and disease detection and prevention systems. Based on a comprehensive literature survey, this paper introduces a research proposal focusing on water quality monitoring and disease prevention in fish. The progress thus far encompasses the selection of hardware components, sensor testing, and ongoing activities in programming and debugging.

Coupling of a zonal air and temperature distribution model with an low pressure environmental control system ducting model

The Regional Cabin Demonstrator is developed within the Clean Sky 2 project and integrates the latest developments in sustainable and high-performance cabin interiors for enhanced passenger experience. Within this project, an innovative low pressure environmental control system (ECS) ducting is developed and integrated into the demonstrator. Together with these hardware demonstration efforts, the associated model based development capabilities are strengthened. The goal is to virtually design the aircraft prior to its actual hardware integration. Such integration requires heterogeneous submodels interaction in an overall aircraft model. The current work presents such a model coupling. On the one hand, a component database for 1D system simulation is developed. By connecting these parameterized component models, it is possible to build any desired low pressure ECS system for which the pressure drop and the air outlet flow distributions are calculated. This system model is interfaced with a zonally decomposed indoor environment Modelica-model of the Regional Cabin Demonstrator showing resulting cabin air temperature, stratification and airflow. Both models interact on the one hand because the air temperature and distribution in the air outlets generates a boundary condition for the zonal model. On the other hand, part of the cabin exhaust air is recirculated and thus generates a boundary condition for the low pressure ECS model. The coupling is performed by the functional mock-up (FMU) standard allowing to couple different models through standardized in- and outputs while maintaining protection of individual partners’ IP. The model application is demonstrated on the example of a cruise condition thermal boundary condition.